Feline orthopedics

Feline orthopedics

Feline Orthopedics John C. C h a n d l e r , BS, D V M , a n d B r i a n S. B e a l e , BS, D V M , D A C V S Although many aspects of canine care ...

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Feline Orthopedics John

C. C h a n d l e r ,

BS, D V M , a n d B r i a n S. B e a l e , BS, D V M , D A C V S

Although many aspects of canine care do cross over to the feline patient, the adage "cats are not small dogs" holds more true today than ever. The area of feline orthopedics is no different. The purpose of this article is to familiarize the reader with the more common feline orthopedic problems. Although many nonsurgical aspects are covered, the majority of text discusses surgical orthopedic problems. In addition, situations considered unique to the feline patient are addressed, including preoperative, perioperative, and postoperative concerns. Diagnostics and implant systems are also covered. Copyright 2002, Elsevier Science (USA). All rights reserved.

ver the last 10 to 15 years, attitudes toward pet care have progressed dramatically. Nowhere has this been as evident as in peoples' attitudes toward cats. Today, for various reasons, cats are living longer, healthier lives. With this, owners are beginning to demand more advanced care for their feline pet. Although many aspects of canine care do cross over to the feline patient, the adage "cats are not small dogs" holds more true today than ever. The area of feline orthopedics is no different. The purpose of this article is to familiarize the reader with the more common feline orthopedic problems. Although many nonsurgical aspects will be covered, the majority of text will discuss surgical orthopedic problems. In addition, situations considered unique to the feline patient will be addressed, including preoperative, perioperative, and postoperative concerns. Diagnostics and implant systems will also be covered.

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Preoperative Considerations Diagnostics As with canine orthopedics, a good history and orthopedic examination are the cornerstones to making the correct diagnosis. Major differences include the cat's willingness to cooperate and basic feline anatomy. Oftentimes it is very difficult to get a gait analysis in the examination room. Most cats will either not move at all or they will slink around the room, making assessment of gait very challenging. It may be necessary to observe the cat through a window or from behind a door, or by having the owners bring a videocassette from home. 1 For these reasons historical information may provide valuable details about the affected limb. Additional dilemmas arise when trying to examine a cat who is in pain or fractious. Sedation may be

From the Colorado State University Department of Clinical Sciences, Fort Collins, Colorado, and Gulf Coast Veterinary Specialists, Small Animal Surgery, Houston, Texas. Address reprint requests to John C. Chandler, DVM, CSU-VTH, 300 W. Drake, Fort Collins, CO 80524. Copyright 2002, Elsevier Science (USA). All rights reserved. 1096-2867/02/1704-0006535.00/0 doi:l 0.1053/svms.2002.36607 190

required after a complete physical examination and a brief orthopedic examination are performed. If possible, always attempt to localize which region of a particular limb is affected and assess neurologic status before sedation. A complete orthopedic examination consists of careful, systemic palpation of all four limbs, generally examining the affected limb last. Palpation while standing, if possible, should be done first to assess any asymmetry that may be present. Always begin palpation of each individual limb at the toenails and work proximal to either the scapula or pelvis. Move each joint through a full range of motion (ROM), paying attention for limited movement, effusion, pain, or crepitus. Palpation of all muscle groups and each long bone should also be performed. Repeat any palpation that elicits an abnormal reaction, as it can be difficult to differentiate uncooperativeness with true discomfort. Remember to assess the neurologic status of the patient as well. When performing an orthopedic examination on the teline patient, it is important to be aware of aspects that are unique to the cat. The most significant difference between the canine and the feline patient is the difference in range of joint motion. These differences have been well-documented, 2 and are most dramatic in the shoulder and hip. In dogs, normal degrees of ROM in the shoulder are 65- to 75-degrees extension, 0 degrees hyperextension, and 40- to 50-degrees adduction and abduction. Comparatively, ' cats normally allow up to 90-degree extension, 20- to 30-degree hyperextension, 80- to 90-degree abduction, and only 20- to 30-degree adduction in the shoulder joint. ROM in the hip of the normal dog is 70 to 80 degrees of flexion and 80 to 90 degrees of extension. In contrast, the cat will allow only 50 to 60 degrees of flexion, but 100 to 110 degrees of extension. Other notable differences include 90 degrees of extension and 10 to 20 degrees of hyperextension of the cat stifle, compared to 65 to 75 degrees of extension and no hyperextension in the dog stifle. Cats also allow much less flexion of the carpus, 130 to 140 degrees compared to 155 to 160 degrees in dogs. Last, cats normally allow twice as much radial deviation (pronation/supination). Cats can have 35 to 40 degrees of radial deviation, but dogs will only allow about 15 to 20 degrees. As with dogs, many diagnostic tools are available after completing a physical and orthopedic examination. Radiography is by far the most used tool in feline orthopedics. In most cases it is essential to have two orthogonal views of the area in question. Occasionally special views will also be needed (e.g., oblique, skyline). Fluoroscopy is also a helpful modality when available. Some applications of fluoroscopy include locating metal objects for removal, contrast studies (arthrogram, myelogram), and intraoperative placement of pins or assessment of fracture alignment. Computer tomography and magnetic resonance imaging can also be valuable modalities in certain situations; however, they are relatively expensive and generally limited to large referral practices or veterinary teaching hospitals at this time.

Clinical Techniques in Small Animal Practice, Vol 17, No 4 (November), 2002: pp 190-203

Nuclear imaging to detect inflammation or neoplasia can be very helpful in localizing lesions before additional studies. U1trasonography has been used in cats on occasion to image tendons and soft-tissue masses. Arthroscopy of the feline joint is becoming a more popular modality for both diagnosis and treatment of intraarticular lesions. However, to date only anecdotal evidence of success with this modality is available. Many different opinions on preoperative laboratory analysis can be found in the literature. 3,* Age guidelines and assigning a physical status number are two ways to determine which laboratory analysis needs to be performed. In general, younger, healthier cats that have presented for elective orthopedic procedures need only a packed cell volume, total protein, and urine-specific gravity performed. Older patients (>5 yr) or patients with preexisting medical conditions require a complete blood count, full biochemical panel, and urinalysis. Some laboratories offer a %urgical panel" that consists of urea, creatinine, serum alkaline phosphatase, and serum alanine aminotransferase. This may be a good option in healthy cats that are younger than 5 years old, but are undergoing a lengthy procedure (>60-90 min). Other laboratory data, such as coagulation profile, electrolytes, and blood gas analysis, may be required to assess differential diagnoses developed on physical examination.* Thoracic radiographs and electrocardiography should be performed on all trauma patients. It has been estimated that 33% to 42% of fracture patients have some degree of pulmonary injury.* Oftentimes these pulmonary injuries (pneumothorax, lung contusion) require delaying repair of orthopedic injuries. The most common posttraumatic arrhythmia is ventricular ectopy, generally in the form of premature ventricular contractions. One study in dogs showed that these arrhythmias may be present for as long as 4 days, and many require preoperative treatment. 5 It is also extremely important to assess and address all other emergency conditions (i.e., shock, bleeding, head trauma) before anesthetizing a patient to repair an orthopedic injury.

Preoperative Medications Pain control and antimicrobials should be considered before surgery. Pain management in cats is addressed by Wright (page 151) in this issue. Preoperative antimicrobials are rarely needed, unless the cat has suffered trauma, and the surgical procedure must be delayed. If indicated, samples for aerobic and anaerobic cultures should be collected before the administration of antibiotics. The most commonly used perioperative antibiotic in orthopedics is cefazolin (Ancef; SmithKlineBeecham, Philadelphia, PA). Cefazolin is generally administered at a dose of 22 mg/kg intravenously (IV) at the beginning of surgery, and repeated every 90 to 120 minutes until the procedure is completed. Other common perioperative antibiotics include ampicillin (ampicillin for injection, USP; BristolMeyers Squibb Co., Princeton, NJ) (22 mg/kg IV), amikacin (Amiglyde-V; Fort Dodge Animal Health, Fort Dodge, IA) (5-10 mg/kg IV), gentamicin (GentaVed Injection; Vedco Inc., St.Joseph, MO) (2-4 mg/kg IV), and cefoxitin (Mefoxin; Merck & Co. Inc., West Point, PA) (22 mg/kg IV). Aminoglycosides should be used with caution because they are potentially nephrotoxic. It may be necessary to continue fluid therapy for 24 hours postoperatively when using these drugs. FELINE ORTHOPEDICS

Implant Systems The successful management of a fracture depends on proper diagnosis and planning. Several variables must be considered before selecting a method of repair. Size and age of the cat, as well as fracture type and concomitant soft-tissue damage, play a large role in selection of the type of repair. Other factors that should be weighed are disease status of the cat, owner's willingness to comply with postoperative management, and the cat's temperament and environment. Cats that are allowed to return outside shortly after fracture repair will require different fixation than strictly indoor cats. The surgeon must also consider equipment availability, cost, and surgeon skill level. Successful fracture repair is a race between healing and implant failure. Contrary to the common belief that fractures in cats will heal if "the bones are placed in the same room"; implant failure, nonunion and other complications occur at a similar rate in cats as in other species. Therefore, the selection of an appropriately placed implant can be the single most important factor in outcome. Several implant systems have been used successfully in feline orthopedics. Intramedullary (IM) pinning has been used for years to effectively reduce fractures in cats. Pin types include Steinmann pins, Kirschner wires (K-wires), and Rush pins. Steinmann pins are available in diameters from 1/16 to 1/4 inch, and may be threaded or smooth. Even large cats will rarely require a pin larger than 1/8 inch. K-wires are similar to Steinmann pins, with diameters of 0.035, 0.045, and 0.062 inch. Rush pins are introduced at an angle such that they flex, and are seated with two to three points of contact within the medullary canal. Because cats have straight bones, relative to dogs, it is possible to fill the entire medullary canal and still maintain anatomic reduction. However, this may lead to disruption of medullary blood supply, and increase risk of delayed union. 6 It is generally best to use a pin that is 60% to 75% of the medullary canal.
Fig 1. Preoperative (A) and postoperative (B) lateral radiographs of a feline mid-diaphyseal spiral humeral fracture repaired using an intramedullary pin and multiple cerclage wire,

fashioned as connecting bars. Selection ot pin size is important because pins too large can weaken the cortex. A good rule of thumb is to select a pin 20% to 30% the bone diameter, which in cats is usually between 0.035 and 3/32 of an inch. The most common type of fixator pin used in cats is a positive profile threaded pin, usually end-threaded. These are readily available as Miniature Fixation Pins (Miniature circular external skeletal fixator, IMEX Veterinary Inc., Longview, TX) or as part of the Small ESF System (Securos Veterinary Orthopedics, Charlton, MA). A recent advance in circular ring fixators may make possible the placement of Ilizarov-type ring fixators in cats with congenital abnormalities and fractures. The Miniature Circular External Skeletal Fixator (IMEX Veterinary Inc., Longview, TX) provides 35-mm rings with 0.035- or 0.045-inch K-wires. Bone plates are commonly used to repair fractures in humans, cats, dogs, and almost any other species (Fig 3). Size becomes the main difference when repairing a fracture in a cat or small kitten. Short bones with a narrow diameter prove to be a challenge when selecting the appropriate size bone plate. Fortunately several different sets of plating equipment are available commercially. The Mini Fragment Instrument and Titanium Implant Set (Synthes, Monument, CO) are equipped with 1.5-, 2.0-, and 2.7-mm bone plates. These plates come as both straight and T-plates. Screws (1.5, 2.0, and 2.7mm) and accessories are also available. The Mini Bone Plating Set and Small Bone Plating Set (Veterinary Orthopedic Implants Inc., Buffalo Grove, IL) provide bone plates that take screws ranging

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from 1.5 to 3.5 mm. The smallest plates are 3.8 and 5.0 m m wide and come as cuttable and dynamic compression plates. Dynamic compression plates (DCP) are available with a variety of hole positions relative to the shank to allow easier application on proximal or distal fractures. Cuttable plates are weaker, but can be stacked to provide greater stability. Another application for cuttable plates in the cat is the plate-rod technique. This technique combines a bone plate and an IM pin to provide stability. In cases of extremely small bones the author (BB) has used the Modular Hand System (Synthes) to apply bone plates. These plates come in 1.0, 1.3, 1.5, 2.0, and 2.4 m m sizes, as DCP, straight, and T-plates. However, this system may be too expensive to purchase for occasional use, and may need to be reserved or borrowed from a local hand and finger surgery specialist.

Nonsurgical Orthopedic Conditions Because many musculoskeletal conditions can be treated without surgery, this section will cover nonsurgical causes of lameness in cats. This section is included as a reminder that systemic diseases can also cause lameness, and should be on your list of differentials when appropriate; such lameness may manifest in the forelimb, hind limb, or both. Abscesses and cellulitis are a common cause of lameness in cats. The sources of most abscesses are puncture wounds associated with a traumatic event, such as cat bites. Physical examCHANDLER AND BEALE

Fig 2. Preoperative (A) and postoperative (B) craniocaudal radiographs of a feline mid-diaphyseal tibial fracture repaired using an interlocking nail. ination will reveal soft-tissue swelling, heat, and usually pain on manipulation of the area. Oftentimes the cat will have a fever or have a recent history of letharg 7} or depression. All areas should be thoroughly examined for trauma. The abscess should be opened and lavaged well. Occasionally, drainage may be necessary. Antimicrobial therapy should be instituted. Abscesses that are unresponsive to therapy or slow to heal may require deep bacterial culture to determine appropriate antibiotic therapy. Feline progressive polyarthritis is a common differential in cats with shifting leg lameness and pain of the distal joints, most frequently in the paws, carpi, and tarsi. Two types of feline progressive polyarthritis exist. 13,14 Proliferative polyarthritis has an acute presentation of fever, stiffness, and painful effused joints. This form occurs in cats from 1 to 5 years of age, and leads to new periosteal bone formation and exostoses. 13,> The less common type of feline polyarthritis resembles rheumatoid arthritis in humans. It has a more chronic, insidious onset that leads to severe crepitus and joint instability. This form occurs in older cats, and can result in crippling joint deformities. > Although no known agent has been identified, it has been reported that all cats with feline progressive polyarthritis are affected with feline syncytium-forming virus, and up to 66% may be positive for feline leukemia virus. 13,14 Diagnosis can be based on radiographs and synovial fluid analysis and culture. Synovial fluid analysis generally indicates nonseptic purulent inflammation, with nucleated cell counts ranging from 4,000 to 70,000 cells/mm 3.~4 Culture of the synovial fluid is negative. Treatment is generally aimed toward immunosuppression, usuFELINE ORTHOPEDICS

ally consisting of a glucocorticoid, either alone or combined with cytotoxic drugs.14 Infectious arthritis affects cats similarly to that seen in dogs. Common types of viral-associated arthritis are feline syncytium-forming virus, feline leukemia virus, and feline calicivirus. Many of the bacterial agents in cats are the same as in dogs (i.e., Escherichia coli, Staphylococcus spp., Pasteurella spp.), and can be obtained via wounds, hematogenous spread, or osteomyelitis. Brucella spp. and Borrelia burgdorferi (Lyme disease) have not been associated with clinical disease in cats, but have been shown to experimentally infect cats. 14 Several case reports of mycoplasmal arthritis in cats exist.14 Mycoplasma gateae and M. fells are the most common forms of feline mycoplasma. Treatment of bacterial arthritis should be based on culture and sensitivity of synovial fluid. Mycoplasma spp. requires special transport media if samples are not cultured relatively quickly, and is not generally included on routine fluid cultures. If empiric treatment is started, a broad-spectrum antibiotic that includes Mycoplasma spp. is recommended. Mucopolysaccharidosis is a disease, seen mainly in the Siamese cat, which is due to a defect in the metabolism of mucopolysaccharides or glycosaminoglycans. 15 These cats generally present with difficulty walking or jumping. Clinical findings include small ears and a broad face, widening of intervertebral spaces, vertebral osteoporosis, corneal opacification, epiphyseal dysplasia of long bones, and pectus excavatum. 15 Osteochondrodysplasia is a form of dwarfism which is seen in several breeds of dogs (basset hound, beagle, dachshund). Recently, the Munchkin cat breed has been created by selecting 193

Fig 3. Preoperative (A) and postoperative (B) ventrodorsal radiographs of a cat with a comminuted femoral fracture and bilateral sacroiliac (SI) luxations. The SI luxations were managed conservatively, whereas the femur injury was addressed with a femoral head and neck ostectomy and fracture repair with a bone plate, screws, and multiple cerclage wire.

for this disorder. 1 To date, no problems with this breed have been described. Another breed in which osteochondrodysplasia has been recognized is the Scottish Fold catl i6 In this breed the disorder leads to exostoses around the tarsal and metatarsal bones, ultimately resulting in ankylosis of the joints.16 Degenerative joint disease (DJD) has been reported to effect as many as 90% of cats older than age 12 years, lr However, most cats with DJD seem to be subclinical because of their ability to compensate for severe orthopedic disease. Clinical signs that have been reported in cats are those of chronic pain, such as a change in attitude or an inability to jump or groom, sr The elbow, shoulder, and hip are affected most commonly, lr,18 Radiographic signs are similar to those in dogs, with osteophytes, joint capsule thickening, and subchondral bone sclerosis all occurring. 19 Treating the clinical feline patient can be difficult because of the lack of safe analgesics in cats. Nonsteroidal anti-inflammatory drugs (NSAIDs) have often been avoided in cats. However, recently many veterinarians are beginning to use select NSAIDs to treat DJD in cats. Carprofen (Rimadyl; Pfizer Animal Health, Exton, PA) has been used without complication by the author at a dose of 4 mg/kg orally every 5 days. Another method of dosing in cats is 2.2 mg/kg orally twice daily. 2~It is important to note that the use of carprofen in cats is extra-label. Ketoprofen is also a commonly used NSAID in cats at a dose of 2 mg/kg orally initially, then subsequent daily doses of 1 mg/kg for 7 to 14 days. Ketoprofen should be used with extreme caution or avoided in geriatric cats or cats with renal insufficiency. Low doses of aspirin can also be used cautiously in cats at a dose of

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81 mg (1 "baby" aspirin) every other day. Many clinicians choose to begin gastrointestinal protective drugs (i.e., sucralfate, famotidine, ranitidine) while having patients on continuous NSAID therapy. Polysulfated glycosaminoglycan (PSGAG) (Adequan; Luitpold Pharmaceuticals Inc, Shirley, NY) has been shown to be an effective chondroprotective agent in dogs, and has been proven safe in cats. 21 PSGAG can be dosed at 5 mg/kg intramuscularly every 4 to 5 days. Caution should be used if a cat has a suspected bleeding disorder because PSGAG is a semisynthetic heparin analogue. = Another popular chondroprotective agent is glucosamine/chondroitin sulfate (Cosequin regular strength; Nutra-max Laboratories Inc, Edgewood, MD). A combination of 250 mg glucosamine with 200 mg sodium chondroitin sulfate can be dosed at 1/2 to 1 capsule daily in cats weighing less than 10 lb, or 1 capsule twice daily in cats more than 10 lb for a minimum of 6 weeks. Then the dose can be decreased to the lowest effective dose, usually 1/2 capsule daily to i capsule every other day in cats less than l0 lb, or 1 capsule daily in cats more than 10 lb.

Surgical Conditions of the Forelimb Orthopedic conditions of the forelimbs in cats are most commonly attributed to trauma. Most of the common conditions of the forelimb seen in dogs (osteochondrosis dissecans, ununited anconeal process, fragmented coronoid process, and angular limb deformities) are rarely, if ever, recognized in cats. Fractures and joint luxations make up the majority of traumatic injuries to the forelimb of the cat. CHANDLER AND BEALE

Scapular fractures can be easily missed on routine physical examination because most are stable and the associated softtissue swelling may be difficult to appreciate. Oftentimes these fractures are found on thoracic radiographs taken subsequent to blunt trauma. There are two important anatomic differences in cats worth noting. Cats have an ossified clavicle that can easily be misdiagnosed as a fracture of the scapula on radiographs. A caudal projection of the acromion, the suprahumate process, is also present. Fractures involving the body or spine of the scapula can usually be treated closed with 2 to 4 weeks of cage rest. If the fracture is unstable it may be treated with a Velpeau sling, a bone plate (2.0 or 2.7 mm), or wire. The wire can be placed in as a figure-of-eight tension band through predrilled holes in the scapular spine, 22 Care should be taken when repairing a scapular body or spine fracture in the cat because the bone is very thin and prone to further splintering or fractures. Fractures of the scapular neck or glenoid are usually Severely displaced and require internal fixation and stabilization. Primary fixation with K-wires, small screws, or a bone plate (DCP or T-plate) is recommended. Reduction should be as anatomic as possible because the joint surface is involved. If the fragments are too small to reduce, an excision arthroplasty or arthrodesis may be necessary. Scapular dislocation is rare, and occurs with rupture of the serratus muscle secondary to trauma. The result is a marked upward displacement o f the Scapula, and a laterally displaced proximal scapula when the distal limb is adducted. 22 Closed reduction and a Velpeau sling have been reported as a successful means of treatment in cats. = Shoulder instability or luxation in cats is most commonly secondary to trauma, and can be treated similarly to those in dogs. Low-grade injuries, which result only in instability, may be diagnosed and treated arthroscopically. 23 If primary repair fails or is not an option, arthrodesis of the shoulder joint has proven successful. Humeral fractures make up approximately 5% of fractures in cats. 24 The majority of these fractures-involve the distal onehalf of the diaphysis (see Fig 1).25 Because of this, many of these fractures involve the condyle and are poorly responsive to external coaptation. Lateral condylar fractures occur less frequently than in dogs. An important anatomical difference in cats is the supracondylar foramen on the medial epicondyle. The median nerve and brachial vessels pass through this foramen. If entrapment of the median nerve is likely, the medial wall of the foramen can be removed. 25 As in dogs, the radial nerve is also prone to injury with humeral fractures, Therefore, thorough neurologic assessment is necessary. Internal fixation can be accomplished using plates, screws, IN, or IM pinning. Fracture reduction and application of these implants is similar in cats and dogs. Orthopedic diseases of the elbow are very rare in cats. However, traumatic luxations of the elbow are a common injury, whereas congenital luxation is unreported in cats. 26 The vast majority of traumatic elbow luxations are lateral. Caudal displacement also occurs more frequently in cats than dogs. 25 Closed reduction under general anesthesia is usually difficult to accomplish, but can be successful in acute cases with minimal collateral ligament damage. To perform closed reduction, the elbow is flexed to move the anconeal process into the olecranon fossa. Then the antebrachium is internally rotated and abducted. If closed reduction is unsuccessful or there is extensive soft-tissue damage, surgical reduction and stabilization is required. Temporary transfixation with the joint at a standing FELINE ORTHOPEDICS

angle is an acceptable method of maintaining reduction? 5 A small (0.062 inch) K-wire can be driven from the humerus into the radial head or from the olecranon into the humerus. 25 Aftercare generally requires immobilization of the elbow joint with an over-the-shoulder spica splint for 14 to 21 days. An additional 4 to 6 weeks of restricted activity should be ordered after removal of the splint and implant. Although the author (BB) has one unpublished case of feline fragmented medial coronoid process, this disease, as well as osteochondrosis dissecans, ununited anconeal process, and elbow incongruity, are rarely recognized in cats. In a recent study 17, the elbow was found to have radiographic evidence of DJD in i7% of geriatric feline patients that had presented for unrelated problems. This study also reported that the elbow was the most likely appendicular joint to have severe lesions, comprising 80% of the severe lesions identified. No underlying cause could be established in these cases; however, arthroscopic examination was not performed. In cats with severe disorders of the elbow, arthrodesis is a practical alternative to amputation, which will allow the cat to remain pain free. 27 However, limb function may be severely compromised. Situations like this may arise with a Monteggia fracture, which is a dislocation of the radial head in conjunction with an ulnar fracture. Fractures of the radius and ulnaare also relatively infrequent in cats, composing only about 3% of all bone fractures. 24 Radius and ulna fractures have been reported as second only to hard palate fractures in cases of feline high-rise syndrome. 28 Although the same principles of treatment of radius/ulna fractures apply for cats and dogs, it is important to remember that cats have a greater ability to pronate and supinate the antebrachium and forepaw. Therefore fixation of the radius or ulna alone is less likely to result in stable fixation of the adjacent bone. 25 With this in mind, it may be necessary to repair both fractures, especially if one or both are comminuted. Most radius/ulna fractures can be repaired with a bone plate or by applying an external fixator. A single IM pin inserted into the fractured ulna will usually provide sufficient ancillary stability if needed. Fractures of the olecranon are most frequently repaired using the pin and tension band technique. Carpal fractures in cats are uncommon. 25 However, theses fractures are commonly seen with high-rise syndrome, a8 When the fragments are relatively large, it is possible to use small screws or K wires to repair the fracture. External fixation is also a reasonable method of fixation. A transarticular external fixator is placed for approximately 4 to 6 weeks, or until radiographic healing is present. The result is typically a functional ankylosis, with loss of ROM. 25 In some cases arthrodesis of the joint may be necessary. Luxation of the radlocarpal joint is often a concurrent injury. Reduction can be maintained with external fixation or a K-wire. Open reduction may be necessary to obtain proper alignment and placement of fixation. Shearing. injuries, usually resulting from motor vehicle trauma, require a higher degree of management because of the severe soft-tissue damage. The wound should be treated with daily lavage, debridement, and wet-to-dry bandages. Bacterial culture and sensitivity and appropriate antibiotic therapy should be instituted immediately. After a healthy bed of granulation tissue is formed, stabilization of the joint may be performed. Fractures of the metacarpals typically are the result of being stepped on, trapped under a rigid object, or a fall (high-rise syndrome). The weight-bearing metacarpals are metacarpal III 195

and metacarpal IV. A cast or splint may be used to treat fractures involving one or two metacarpals, if one of the weight bearing metacarpals are intact. 25,29 Internal fixation is required if three or four metacarpals are fractured, metacarpals III and IV are fractured, severe displacement or comminution exists, articular fractures are involved, or basilar fractures of metacarpal II or V are present. 29 The most practical type of internal fixation is IM pinning; however, plating is possible. Miniplates (Modular Hand System, Synthes) of sizes 1.0 mm to 2.4 mm can be useful for this technique. At least two of the fractured metacarpals, preferably metacarpals III and IV, should be repaired. 25,29 Alternatively, K-wires can be placed in retrograde fashion, cut and countersunk. Digital fractures are discussed in the hind limb section.

Surgical Conditions of the Hind Limb Orthopedic conditions of the hind limbs in cats are much more prevalent than the fore limbs. Many of the developmental diseases of the pelvic limbs that are seen in dogs also occur in cats. Conditions such as patellar luxation and hip dysplasia frequently occur in cats. Almost 75% of all fractures in cats involve the pelvis or hind limb. 24 Pelvic fractures generally are the result of trauma. Vehicular trauma, dog bites, blunt trauma, falling, and gunshot wounds are common causes. 24 Pelvic/sacral fractures make up about 22% to 25% of all fractures. 24,3~ These fractures tend to be multiple, and have related, severe soft-tissue injury. Five categories of pelvic fractures exist, and each should be evaluated. Although no studies have been done in cats, iliac fractures are the most common type of pelvic fracture seen in dogs. Followed by (in order) pubic fractures, acetabular fractures, ischial fractures, and sacroiliac fracture/luxation. 3~ Triage is especially important with pelvic fractures because of the relatively high likelihood of concurrent abdominal, neurologic, and genitourinary injuries. A rectal examination should always be performed to determine the extent of injury to the pelvic canal. Neurologic examination of the perineum/anus should be performed, in addition to the hind limbs. Cats with sacral fractures or sacroiliac luxations may lack good anal tone and perineal sensation. Most cats with perineal sensation at presentation will fully recover over time. In general, ischial and pubic fractures rarely require fixation. Most cats with these fractures do very well with crate confinement for 4 to 6 weeks. The most important factors in conservative management of pelvic fractures are case selection and owner compliance. Occasionally these fractures do require fixation. Indications for pelvic fracture reduction and stabilization include markedly displaced fractures, narrowing of the pelvic canal, and intractable pain. Because the ilium is a weight-bearing surface, iliac fractures almost always require surgical intervention. Most of these fractures are oblique and can be easily reduced and stabilized with a bone plate. Unlike the laterally bowed ilium of the dog, cats have a relatively fiat or parallel ilium. This increases the acceptance of a bone plate. The techniques for repair of iliac fractures in dogs also apply in cats. Because weight is supported through the cranial two-thirds of the acetabulum, fractures of the cranial and middle third of the articular surface require surgical attention. These types of fractures can be reduced and stabilized, or a femoral head and neck ostectomy (FHO) can be performed (Fig 4). Unlike larger dogs, cats tend to have a good prognosis after having a FHO. Acetab-

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Fig 4. Postoperative ventrodorsal radiograph of a mid-acetabular fracture, addressed with a femoral head and neck ostectomy.

ular fractures that are treated conservatively or that are poorly managed surgically often lead to severe degenerative changes of the coxofemoral joint. Surgical indications in the case of sacroiliac fracture/luxation include severe pain, distinct instability, or bilateral instability. Fortunately unilateral separation occurs much more frequently than bilateral luxation. 3~ Peripheral nerve injury is common with these types of pelvic fractures; however, most will regain good or excellent function over time. Reduction and stabilization of these injuries are similar to those described in dogs. Conditions that require surgical intervention of the feline hip joint are divided into traumatic and nontraumatic categories. 3~ Aseptic necrosis (Legg-Calve-Perthes disease) has not been reported in cats. Feline hip dysplasia (FHD) (Fig 5) has been reported in cats as far back as 1964. 32 However, until recently very little attention has been given to the clinical features of FHD. Although work is being performed, data are still lacking regarding the genetic components, prevalence, and prognostic measurements of FHD. Maine Coon cats appear to be predisposed to FHD, and are listed with the Orthopedic Foundation of America (OFA). The prevalence of FHD in this breed has been reported as high as 50% using OFA-like scoring. 33 This study also reported a significant difference in distraction index (DI) between cats subjectively scored disease-free and those subjectively scored dysplastic. The DI of this group of cats was similar to that of dogs with high frequency of hip dysplasia, such as the Neapolitan Mastiff, Newfoundland, and Saint Bernard. A relationship between DJD and hip laxity has also been made using the Norberg angle in cats. 18 Results of this study CHANDLER AND BEALE

Fig 5. Ventrodorsal radiograph of the pelvis of a cat with severe hip dysplasia.

indicated that cats (of several breeds) with DJD had a lower Norberg angle and a higher DI than cats without DJD. The DI of this group of cats was similar to that of the Labrador retriever, golden retriever, and Gordon Setter. Cats with FHD rarely present with hind limb lameness or pain, but rather stiffness or reluctance to jump or run. Many times FHD is diagnosed as an incidental finding during radiograph of the abdomen. Because of the lack of clinical relevance in many cases, treatment with weight loss and NSAIDs (as previously discussed) is recommended. In cases with clinical lameness, femoral head and neck excision arthroplasty is recommended. Coxofemoral luxation is a common injury in cats suffering trauma. Craniodorsal luxation is most common. Diagnosis can be made by palpation of the greater trochanter and tuber ischium. The thumb test has been described as displacement of a thumb or finger placed in the indention between these two landmarks. If this displacement does not occur, a craniodorsal coxofemoral luxation should be suspected. Lateral radiographs also aid in diagnosis. Closed reduction of the luxation is possible in most cases, but the rate of reluxation is high. If the reduction is stable, no preexisting hip abnormalities are present (i.e., shallow acetabulum, DJD), and no fractures/fragments of the acetabulum are present, an Ehmer sling should be placed. This type of sling provides internal rotation and abduction, allowing the hip joint time to heal. This sling should stay in place for 14 to 21 days. If concurrent limb injuries are present, open reduction and primary repair are indicated. A craniolateral approach to the hip is most commonly used. This approach differs from that in dogs in that the tensor fascia lata is broader in cats and may require a longer incision through the insertion, and the vastus lateralis is also broader and will require more subperiosteal elevation to gain adequate exposure to the femoral neck. 3~ Open reduction and stabilization can be performed by similar means as those in dogs. Capsulorraphy along with an Ehmer sling, transarticular pin, or toggle rod can be successful. The use of the DeVita pin technique is contraindicated in cats because the fiat conformation of the ilium leads to difficulty placing the pin. 25,31 As a result, sciatic nerve damage has been reported. Femoral head and neck arthroplasty is also a reasonable treatment, given the excellent results obtained. Most cats will have complete recovery within 5 weeks. Recurrence of coxofemoral luxation has been reported with both open and FELINE ORTHOPEDICS

closed reduction. 3x Rates of recurrence with open reduction are much lower than those of closed reduction. 34 Therefore, cases which have reluxation after closed reduction should undergo open reduction and stabilization or FHO. Femoral fractures are the most common long bone fracture in dogs and cats (see Fig 3). 24,z5 The most common site of fracture is the femoral shaft (56%).35 Physeal fractures are the second most common type of femoral fracture (20%). Distal physeal fractures occur slightly more often than proximal physeal fractures. The majority of these fractures are Salter-Harris type I or II. Proximal femoral physeal fractures or slipped capital femoral epiphysis should undergo primary stabilization by using two or more parallel 0.035- or 0.045-inch K-wires. 36 The K-wires are inserted into the femoral neck from the lateral side of the femoral shaft, at the level of the third trochanter. The pin is advanced until just visible, then withdrawn slightly below the level of the articular cartilage. An alternative to primary repair is FHO. Although the majority of slipped capital femoral epiphysis (SCFE) occur secondary to trauma, a genetic predisposition to physeal dysplasia may lead to atraumatic injuries. Abnormal physeal development has been documented in 13 cats. Five of these cats suffered bilateral SCFE. 37 Histopathology suggests that these lesions where similar to those seen in humans, pigs, and Shetland sheepdogs. This physeal dysplasia results in persistence of an open, disorganized growth plate that cannot resist the shear forces associated with normal activity. An over-representation of Siamese cats, male cats, and the occurrence in siblings are supportive of a genetic etiology. Avulsion of the greater trochanter is seen in young kittens with open physes. This physis is generally open until 7 to 8 months of age. Internal stabilization is indicated if the greater trochanter is displaced. Small K-wires and a figure-eight tension band are sufficient to overcome the avulsive forces. Fractures of the femoral neck usually occur in adult cats and mainly involve the base of the femoral neck. Multiple K-wires or a lag screw can be used to repair these fractures. Results of internal stabilization are usually good. A femoral head and neck ostectomy is also a reasonable procedure, especially when reduction and internal stabilization are not an option. A new disease, that most closely resembles Legg-Calve-Perthes disease has recently been described and can lead to femoral neck fractures. 38 Femoral neck metaphyseal osteopathy has been described in 17 male cats, 4 of which were affected bilaterally. Radiographic findings showed primary loss of bone in the proximal metaphysis of the femur and the femoral neck. These lesions subsequently lead to pathologic fracture of the femoral neck. Excision arthroplasty and submittal for histopathology is the recommended treatment for these cases. As previously mentioned, diaphyseal femoral fractures are very common. External coaptation of the femur is usually discouraged because of difficulty immobilizing the hip joint. Therefore, open reduction and stabilization is almost always the recommended course. One anatomic difference that may be important in the surgical approach to the femoral diaphysis is that cats have an undivided sartorius muscle, whereas dogs have cranial and caudal bellies. Also, the femur of the cat is much straighter than that of the dog and the diameter of the medullary canal is much more uniform throughout the length of the bone. This makes IM pinning easier in the cat because the implant is less difficult to place and fills the medullary canal better, leading to greater stability. Other techniques that have been proven successful include stack IM pinning, interlocking 197

nails, bone plates, and external fixators, and combinations such as plate/rod, external fixator/IM pin tie-in, and bone plate/IN. Additional, secondary fixation can also be used. Implants such as cerclage wire, K-wires, and screws can be helpful. As with dogs, cancellous bone grafts harvested from the ilial crest, humeral head, or tibial crest can be helpful to span deficits in comminuted fractures. Damage to the sciatic nerve occurs in similar fashion as in canine patients. Contrary to popular belief, cats can and do suffer from quadriceps contracture secondary to fracture disease. 39,4~As with dogs, the limb is contracted in rigid extension. The ROM of the stifle and hock are severely compromised. In one study, 4~quadriceps contracture was the most common complication observed in cats with femoral fractures, and surgeon experience did not make a difference in outcome. Management of animals with quadriceps contracture can prove difficult. Recently, the management of this complication has been reported successful with the use of a dynamic flexion apparatus. 41 In this report, the ROM in the stifle was improved from 35 degrees to 130 degrees. As with the humerus, fractures of the distal femur can difficult to repair. Open reduction and internal fixation is usually indicated. 25 Supracondylar fractures can be held stable with cross-pin fixation. If a T or Y fracture of the condyle is present, the use of small K-wires or a screw is indicated. Fractures of the distal femoral physis can be repaired similar to supracondylar fractures. Trochlear femoral fractures are slightly different from other condylar fractures, in that they may have several lines of fracture crossing the femoral trochlea in oblique or horizontal patterns. Bone plates, including DCP and L-plates, have been reported as successful means of stablization. 4z Fractures of the distal femur must be repaired with precise alignment and apposition. Because articular surfaces are affected, sub-optimal repair can lead to DJD and decreased use of the limb. Fractures of the patella are rare in cats. Surgical fixation is indicated if the fragments are displaced. Small pins (0.062 inch) or interfragmentary wire is generally enough-to provide stability. Conservatively managed patellar fractures can lead to persistent lameness and DJD. 43 Disorders affecting the feline stifle are common. Anatomically the feline stifle is very similar to the canine stifle. One difference of note is that the cranial cruciate ligament is larger than the caudal cruciate ligament in the cat, while in dogs the cranial cruciate ligament is smallerr 4 This may account for the differences in incidence of cranial cruciate ligament ruptures (CCLR) in cats. Also, in contrast to dogs, the majority of CCLR are due to trauma. Diagnosis of CCLR in cats is identical to that of dogs. cranial drawer is usually present in cases with complete~rupCure. Radiographic evidence of CCLR consists of joint effusion and periarticular osteophytes. Treatment of CCLR in cats is controversial. Lack of good data concerning the outcome of surgically and nonsurgically treated CCLR in cats has left much of today's management to opinion. Many surgeons believe conservation management with cage confinement for 30 days provides adequate outcome. However, one report confirmed cranial drawer, periarticular thickening, and radiographic evidence DJD on long-term follow up of cats treated conservativelyr In this report none of the cats examined were clinically lame on follow-up. Despite this, the authors' recommendation is to stabilize the stifle using an extracapsular technique. It is our opinion that these cats have less stifle DJD/OA, periarticular fibrosis, and pain after stabilization is complete. One of the authors (BB) has 1~8

been successful at using arthroscopy to examine and treat intraarticular injuries related to CCLR in cats. As with dogs, cats are prone to medial meniscal tears secondary to CCLR. These lesions should be treated with partial or complete meniscectomy. Meniscal calcification and ossification has also been reported in the medial and lateral meniscus of both stable and unstable feline stifles. 45,46Although the relationship is unclear, the majority of these cats had lesions of the medial meniscus and CCLR. The recommended treatment for meniscal calcification and ossification is meniscectomy and stabilization of the stifle. Injuries to the caudal cruciate ligament alone are extremely rare. Rupture of the caudal cruciate usually accompanies CCLR and collateral ligament tears. When isolated, caudal cruciate ruptures can be treated conservatively with several weeks of rest. 43 Collateral ligament injury occurs most frequently with vehicular trauma and falls. As with caudal cruciate ligament tears, these injuries usually occur together. Medial collateral injuries occur more frequently than lateral collateral injuries. 43 Palpation of the stifle should be performed under heavy sedation or general anesthesia. Conservative management of these injuries usually results in long-term lameness, joint instability, and DJD. 43 Therefore surgical repair should usually be performed. The use of a locking-loop suture pattern is effective in reapposing the torn ligament ends. An alternative, stronger, fixation uses screws and Teflon-spiked washers a t the origins of the ligament. 43,47 Suture material is then passed around each screw head to allow stabilization of the ligament. Derangement of the stifle (disruption of the cruciate ligaments, collateral ligaments, joint capsule and menisci) is relatively uncommon. Luxation of the stifle can occur and is typically secondary to trauma. Diagnosis is be made by palpation; craniocaudal and mediolateral instability is usually present in the absence of fractures. 48 Swelling of the stifle is usually extensive. Therefore, it is not uncommon to allow healing of the soft tissue for several days before stabilization. Treatment of these injuries remains somewhat controversial. Acceptable techniques include arthrodesis, ligament reconstruction, transarticular pinning, and ligament construction with transarticular e x t e r n a l fixaion. 43,49,5~Ligament reconstruction consists of stabilizing each torn component as previously mentioned. A modified Robert Jones bandage should be placed for 10 to 14 days, followed by restricted activity for 2 to 3 months. Transarticular pinning and external coaptation has proven to be an excellent means 0f fixation. 4s,49 The use of a sufficient size d IM pin (--> 1/8 inch) is necessary, as small diameter pins have the tendency to bend prior to stabilization of the joint. The pin should be left in place 3 to 4 weeks, followed by restricted activity for approximately 2 months. Combination of ligament reconstruction with transarticular external fixation also yielded excellent long-term results, s~ However, three of the four cats in this report escaped before external fixator removal and subsequently suffered a fracture on the ipsilateral limb at the level of one of the transcortical pins. Patellar luxation is less frequent in cats than dogs. Most commonly the patella luxates medially. The luxation in cats is generally intermittent and associated with a mechanical, nonpainful lameness. 47 Predisposed breeds include the Devon Rex and the Abyssinian. 51,52Although patellar luxation in dogs has numerous etiologies, medial patellar luxation in the cat is usually the result of a shallow trochlear groove or medial deviation of the tibial crest. 53 A weak association between medial patellar CHANDI FR AND RFAI F

luxation and hip dysplasia has been made in cats. 54 Diagnosis and grading is similar to that in dogs. Treatment is directed at the underlying etiology. A trochleoplasty is usually necessary tO deepen the trochlear groove. Several techniques exist and are selected by surgeon preference. Transposition of the tibial tuberosity is also required in most cases. This is accomplished by elevating the tibial tuberosity via osteotomes or saw, and transposing it laterally. The tuberosity is held in its new position using small K-wires. Outcome depends on the degree of preexisting osteoarthritis at the time of surgery. Tibial fractures comprise approximately 10% of all fractures in cats (see Fig 2). 24 Diaphyseal fractures are most common. Techniques and principles in repairing tibial fractures in cats are similar to those in dogs. Several different methods of repair are acceptable. Use of IM pinning, external fixation, bone plating, IN, and external coaptation have all produced good results when placed appropriately. Delayed union or nonunion can occur from the lack of soft-tissue attachments in this region. 25 For the same reason, open fractures of the tibia are common: Infection can be a major complication in these cases. Care should be taken to perform deep cultures and provide appropriate antibiotic coverage. Injury of the tarsus and metatarsus are relatively common. These fractures are a result of vehicular accidents, dog bites, falling, and being stepped on or crushed. These injuries can be fractures, luxations, or ruptures of ligaments. Conservative treatment or primary repair of tarsal injuries can be successful with proper case selection. Cases with minimal instability will usually respond well to a lateral splint and soft-padded bandage. Cats that have greater instability should undergo surgical intervention. This can be accomplished in similar fashion as carpal injuries. The use of K-wires and screws has proven successful. 25,55 External skeletal fixation was shown to be a successful treatment in five cases of talar neck fractures. 56 Arthrodesis is also a reasonable method of repair in cases with severe tarsal derangement. Metatarsal fractures can be managed the same as metacarpal fractures, which has been previously discussed. Digital fractures, fore or hind, rarely result in long-term lameness. Conservative management with activity restriction will generally result in a good outcome. A palmar/plantar splint may be placed for 5 to 7 days if the cat is in extreme pain. In cases of open fractures, removal of the exposed bone and treatment of soft-tissue injury may be all that is necessary.

Surgical Conditions of the Axial Skeleton 9Skull and mandibular fractures are usually the result of significant trauma. As with all fractures, triage of other injuries is very important. Brain injuries can be associated with the trauma, as can ocular and airway damage. The majority of these fractures are open; therefore, wound management and antibiotic therapy are important. 57 Pharyngeal intubation can be helpful during repair of these injuries. This technique allows for a secure airway while freeing space in the oral cavity for fracture reduction and manipulation instruments. The technique has previously been described in the l i t e r a t u r e s Fractures of the skull are usually accompanied by neurologic dysfunction. Treatment of neurologic deficits should always precede treatment of orthopedic injuries. Most Cats with mild to moderate neurologic dysfunction will respond to medical management. 25 Surgical treatment is rarely necessary in these cases. FELINE ORTHOPEDICS

Occasionally the eye will be at risk of damage from the fragments. If this is the case, the fragments can be reduced and stabilized using interfragmentary wire. Many skull fractures will pierce the frontal sinus. A compressive bandage can be placed to decrease subcutaneous emphysema until adjacent soft tissues seal the puncture. Fractures entering the cranium should be elevated to relieve compression on the brain. This can be accomplished by lifting the fragments from inside the cranium by passing a curved, blunt probe through adjacent bur holes. 5r Direct elevation by levering the fragments usually results in further fragmenting of the edges of the original hole. Fractures of the face and palate are often accompanied by epistaxis, severe facial swelling, and subcutaneous emphysema. Depressions in the face may also be noted. Hard palate fractures most commonly present as a longitudinal cleft on the dorsal midline of the oral cavity. 25 Nondisplaced fractures require no treatment or only suturing of the mucosal t e a r y Displaced fractures can be stabilized with interdental wiring between the corresponding left and right molars, or sutured closed using heavy absorbable material. Maxillary fractures can be treated with small bone plates, interfragmentary wires, or interarcade wire when surgical stabilization is necessary. The techniques are very similar to those of mandibular fracture repair. Mandibular fractures are a common injury secondary to falling or blunt trauma. Untreated-these fractures can result in malocclusion, leading to difficulty eating, abnormal dental wear, and pain. Other complications are delayed or nonunion and infection. Mandibular symphyseal fractures usually carry a good prognosis and are relatively simple to repair. The most common repair technique involves passing a single stainless steel wire under the gingiva and behind the canine teeth in an encircling fashion. The wire is then twisted to bring the symphysi s into apposition. Removal of the wire can be performed after 3 to 4 weeks. Fractures of the mandibular body can be more difficult to repair. Treatment techniques in cats include interarcade wiring, interdental wiring, interfragmentary wiring, acrylic splinting, placement of bone plates, and external fixators. Interarcade wiring involves passing loops of wire transversely from the maxilla to the mandible. This should be done on both sides of the oral cavity. Care should be taken to avoid tooth roots. Enough room should be left between the upper and lower incisions to allow the cats to lap water and liquid gruel. Interdental wiring is useful in transverse fractures of the mandibular body. This can be accomplished by passing a single stainless steel wire (20-24 gauge) through preplaced holes in the gingiva at the neck of the tooth. The wire should be positioned around the teeth that are separated by the fracture. The temptation to overtighten the wire must be avoided as this causes opening of the ventral mandibular border. 5r Interfragmentary wire is useful in stabilizing transverse or short oblique fractures. Loops of stainless steel wire are placed across the fracture line and twisted until the fracture is reduced. At least two wires should be placed across the fracture to assure adequate stability. 5r Acrylic splinting involves molding a dental acrylic material to lye across the teeth. A routine dental should be performed before placement of the acrylic to ensure bonding of the material to the enamel. Assure proper apposition of the fracture and occlusion of the teeth before hardening of the acrylic. After 3 to 4 weeks the acrylic can be chipped off of the teeth. Bone plates have been proven very successful in the repair of several types of mandibular body fractures. 5s,59 Small plates can 199

be easily contoured to the surface of the mandible, which can aid repair of complicated or comminuted fractures. Although the tension side of the mandible is along the alveolar border, plates are often applied through lateral or ventral approaches to avoid tooth roots and the mandibular nerve. 57 External fixation is also a good technique for the treatment of complicated or highly comminuted fractures. A large advantage is that the fixation pins can be placed in any direction to avoid tooth roots. The connecting bar can be fashioned out of acrylic, which allows for easy shaping and molding. Partial mandibulectomy can also be performed for unrepairable fractures or as a salvage procedure for nonunions. Enough bone is resected to remove all abnormal tissue but still allow tension-free closure of the soft t i s s u e s Luxation of the temporomandibular joint (TMJ) occurs when the mandibular condyle is displaced either caudally or rostrally relative to the mandibular fossa. TMJ luxations can occur unilaterally or bilaterally. Physical examination generally reveals malocclusion of the teeth and difficulty opening and closing the oral cavity, The majority of TMJ luxations can be treated by closed reduction using the standard wooden dowel technique. In cats, a pencil is usually sufficient. The pencil is placed between the last molars to act as a lever. Force is then applied to push the mandible and maxilla together. After the caudal portion of the mandible is levered open, the mandible can be pulled rostrally to allow the condyle to fall back into the fossa. Some luxations may not reduce initially. Because tape muzzles are difficult in cats, interarcade wiring is usually necessary to hold the TMJ in reduction. The wiring can usually be removed in 10 to 14 days. Temporomandibular ankylosis is a condition associated with TMJ luxation and other facial fractures. Arthroplastic excision of the TMJ and stretching of the jaws under anesthesia have been successful in treatment of this complication. 6o Aftercare of facial or mandibular fractures should be geared toward good pain management, nutrition, arid hydration. Many cats will refuse to eat or drink after these types of injuries, especially if their jaws are wired closed. Placement of a feeding tube may be necessary. Esophageal and stomach feeding tubes work well in these situations because the cat can be sent home with them in place. Be certain to provide proper instruction to the owner on feeding schedules, tube maintenance (cleaning), nutrition and water requirements, and potential complications. Spinal fractures occur most frequently as a result of vehicular trauma. 61 Most spinal fractures or luxations (50% to 60%) occur betvgeen T l l and L6. 6~ Many of these patients also present with concurrent injuries, such as pneumothorax, lung contusion, diaphragmatic hernia, abdominal injury, and concurrent fractures. Cau{ion should be taken during physical examination. Exacerbation of spinal injury by excessive movement can occur. Patients should be secured to a rigid board to prevent them from moving. A thorough neurologic examination can aid in neuroanatomic localization of the lesion. It is important to remember that approximately 20% of patients with one spinal fracture will have a second. 6~ Radiographs are of limited use for evaluating thoracic and lumbar spinal trauma. 6~ Radiographs that show minimal displacement may not tell the whole story. Oftentimes fractures or luxations will undergo spontaneous reduction before radiography. Therefore, lesions with minimal displacement on radiographs can still result in severe spinal trauma. Generally prognosis can be based on neurologic examination. Myelography, comlSuted t0mography and magnetic 20{}

resonance imaging are the definitive diagnostic procedures to determine extent of spinal cord injury. The success of nonsurgical management of spinal fractures depends on case selection, appropriate therapy, nursing care, and owner/animal compliance. Medical management should not be recommended for cats that have radiologic evidence of vertebral instability or significant vertebral canal compression. 62 Therapy consists of strict cage rest for 4 to 8 weeks, external stability (back brace or body splint), anti-inflammatory medication, pain management, serial neurologic examination, and nursing care. Nonambulatory patients should have easy access to food and water in a well-padded, dry cage. Bladder and bowel management should be performed 3 to 4 times daily. If the cat will tolerate physical therapy (passive range of motion exercises), it can be started when the patient is comfortable. Many techniques of surgical stabilization exist. Because of the difficulty in both the surgical procedure and aftercare, most cats .with spinal fractures that require surgical intervention should be referred.

Postoperative Considerations Postoperative care and monitoring after orthopedic procedures are critical for success of surgical treatment. 63 Smooth anesthetic recovery and good pain management can reduce stress, which can lead to faster recovery times. Propef monitoring must be continued until the cat is able to resume normal function. Cardiac and respiratory functions are most critical. Monitoring of patients does not prevent complications from arising, but allows the clinician the foresight to act prior to problems. Body temperature should be watched closely during the postoperative period. Warm, dry bedding should be provided. Cats with body temperatures lower than 99 ~ to 100~ (37.5~ should not be left alone. Decreased temperature leads to slow metabolism and prolonged anesthetic recovery. Occasionally patients will require additional fluid therapy after surgery. Fluids aid in cardiovascular function and help replace losses incurred during surgery. Geriatric cats or cats with renal disease should be maintained on intravenous fluids to assure adequate cardiac output and renal perfusion. Postoperative Medication Postoperative pain management is essential to the well being and recovery of the feline patient. Unfortunately this aspect of patient management is often overlooked. As discussed previously with regard to preoperative pain management and management of nonsurgical orthopedic conditions, many options for pain relief do exist for the feline patient. Inappropriate antibiotic administration can lead to resistant strains of bacteria or induce a superinfection that may be difficult to control and may be disastrous to the surgical repair. 63 Indications for continued antibiotic use include open contaminated fractures, procedures that last longer than 2 hours, or cases in which sterile technique was breached. Surgical procedures involving implants generally do not need to be continued on antibiotic therapy. Antibiotics administered because of the presence of open wounds should be based on results of bacterial culture and antimicrobial sensitivity. The most common organisms found in osteomyelitis are Staphylococcus spp., Streptococcus spp., Proteus spp., E. coli, Pasteurella multocida, Pseudomonas spp., and Klebsiella Spp. 63 Common postoperative CHANDLER AND BEALE

antibiotics include cephalosporins, acid, and clindamycin.

amoxicillin-clavulanic

Bandaging The proper placement of external coaptation can often be as important to long-term outcome as the surgical procedure. The most common types of bandages used in feline orthopedics are the Robert-Jones bandage, the modified Robert-Jones bandage (soft-padded bandage), rigid casts, and splints. Indications for a Robert-Jones bandage include wounds, fractures, and luxations distal to the elbow or stifle. 64 This bandage is not meant to provide support for fracture healing. It is intended to aid in managing severe swelling, preoperative or postoperative, or for temporary support when surgery must be delayed. A modified Robert-Jones bandage is different from a RobertJones in that cast padding is used instead of roll cotton. The indications and goals of the bandage are the same, without the bulkiness. A modified Robert-Jones bandage does not provide quite as much compression as a Robert-Jones. Rigid casts may provide acceptable fracture management in certain cases. Casts should only be used for fractures that are closed and distal to the elbow or stifle. 64 In addition, the fracture must be able to be reduced closed and remain stable in the cast. The cast must incorporate the joints above and below the fracture. Complications from casts include cast sores and fracture disease. Cast sores arise from inappropriately placed casts that slip or are too tight, and when the cast is allowed to get wet. be chewed on. or collect debris and dirt inside. Fracture disease is characterized by chronic edema, muscle atrophy, joint stiffness, and disuse osteoporosis, which can lead to permanent j oint dysfunction.64 Two types of splints are commonly used m cats. Mason metasplints are designed to immobilize the metacarpus and carpus, including the distal radius and ulna. carpus or tarsus. and metacarpal or metatarsal or phalanges. 64 This splint is not intended to immobilize the proximal radius and ulna or the elbow. Fiberglass splints allow more options for application because they are molded. These splints can be placed on the lateral aspect of the fore or hind limb. as well as the plantar aspect of the hind limb. It can be used to immobilize the elbow or stifle and can stabilize minor fractures of the radius, ulna. tibia, and fibula 64 Activity a n d Physical T h e r a p y Knowledge of appropriate activity level postoperatively can aid healing immensely. Patients that have undergone an orthopedic procedure should be confined for 4 to 8 weeks, depending on their health status and procedure. One exception to this rule of thumb is after an FHO. These animals should be encouraged to use the limb immediately to promote healing of the pseudoarthrosis, It is not appropriate to allow a cat to be in pain under the premise that this will discourage activity. Physical therapy can increase rate of recovery and prevent associated soft-tissue complications (contracture). Occasionally physical therapy can be difficult in feline patients because of opposition to physical restraint in some cats. Nonetheless, physical therapy techniques should be attempted in most patients. Types of exercises that w o r k well in cats include passive ROM and muscle massage. Passive ROM prevents inappropriate fibrous tissue formation that could lead to restricted joint motion, as well as preventing muscle contracture. 63 Muscle massage has multiple benefits, which include decrease of muscle adhesions, reducFELINE ORTHOPEDICS

tion of edema, increased blood flow, deactivation of triggerpoints, reduction of muscle spasms, and pain control through activation of alpha nerves in the spinal cord. 63 After a period of inactivity, a 2- to 4-week period of gradual return to normal activity should be implemented. This period allows bones and muscles to gain strength, and joints to regain flexilility. 63 Nutrition Surgical procedures and trauma lead to increased levels of stress. Cats are often affected much more than dogs by this stress. Many cats will refuse to eat or drink during a stay in the hospital or at home after dismissal. High levels of stress and malnutrition can lead to decreased ability to heal. In addition, anorexia in cats can lead to even more severe disease such as hepatic lipidosis. Cats have a much higher requirement for protein than dogs. Dogs have hepatic transaminases that adapt to the amount of protein consumed. Cats have a fixed high rate of activity in transaminase and urea cycle. 63 Therefore, anorexia or low protein diets during stressful periods may lead to complications. Many cats need to be encouraged to eat. Hand feeding and offering several types of food can be helpful. Appetite stimulants can also be helpful, but often do not work in severely anorexic cats. The most common appetite stimulants are cyproheptadine (Periactin; Merck Co, West Point, PA) (2 mg/cat by mouth [PO] twice a day [BID]) and diazepam (Valium: Roche Animal Health and Nutrition, Nutley, NJ) (0.5 mg/cat IV). Other methods of providing nutrition include total parenteral nutrition and enteral feeding. Total parenteral nutrition is rarely necessary in feline orthopedic patients, unless significant concurrent injuries exist. Common routes for enteral feeding in the feline orthopedic patient include oral, nasoesophageal, pharyngostomy, esophagostomy, and gastrostomy. Nasoesophageal tubes are easy, effective and efficient, and work well in cats. 65 These tubes can be left in place for several weeks if needed. Esophagostomy and pharyngostomy tubes can be used in cats with fractures of the oral cavity. These tubes are simple to place, tolerated well by cats, and allow feeding of blenderized diets. It is also possible for the cat to eat and drink around the tube. Several types of gastrostomy tubes exist, and several methods of placement are possible. These are usually based on clinician preference. Advantages of gastrostomy tubes include ease of placement, patient tolerance, ease of feeding and tube care, and oral feeding is still possible with the tube in place. 65 Because of the importance of nutrition in the postoperative patient, veterinarians should not be hesitant to place feeding tubes.

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