The Journal of Emergency Medicine, Vol. 8, pp. 539-543, 1990
Printed in the USA . Copyright 0 1990 Pergamon Press plc
EASE OF CONTINUOUS DERMAL SUTURE REMOVAL Son Pham,
George T. Rodeheaver, Ptq Minh-Chau Dang, BA, Pamela A. Foresman, Jim C. Hwang, BA, Richard F. Edlich, MD, PhD
Department of Plastic Surgery University of Virginia School of Medicine, Charlottesville, Virginia Reprint address: Richard F. Edlich, MD, no, Department of Plastic Surgery, University of Virginia School of Medicine, Charlottesville, VA 22908
0 Abstract - The purpose of this investigation is to identify the synthetic nonabsorbable monofilament suture that requires the lowest forces for removal of continuous dermal sutures. Immediately after wound closure, continuous derma1 polypropylene sutures require the lowest suture removal forces. The ease of polypropylene suture removal from continuous dermal skin closure is related to the suture’s low surface coefficient of friction. 0 Keywords removal
dermal suture; polypropylene;
divided end of the suture protruding from the wound. This unsuccessful suture removal is usually accompanied by discomfort or pain, and becomes a frustrating experience for both the patient and the physician. This study was undertaken to identify the synthetic nonabsorbable monofilament suture that requires the lowest forces for removal when placed as a continuous dermal suture. These suture removal forces were correlated with the suture’s diameter and load elongation properties.
The removable dermal (subcuticular) continuous suture, devised first by Halsted, has been used extensively for skin closure (1). When nonabsorbable sutures are employed for wound closure, it is desirable to use monofilament suture whose configuration facilitates removal (2). When removing this suture from the wound, every physician has had the misfortune of finding it difficult to remove the suture from the wound (3). The suture may be the one that the physician himself placed or it may be in a patient who has appeared for suture removal. When continuous force is applied to the suture, the suture may occasionally remain in the wound or break leaving the
The four synthetic nonabsorbable sutures that are evaluated in this study are nylon, polypropylene, polybutylene terephthalate, and polybutester. The polybutester suture contains a block copolymer composed poly (glycol) terephthalate and polybutylene terephthalate (4). They are supplied in two sizes (3-O and 5-O) swaged to PFUZ4needles (Davis & Geck Co., Danbury, CT). This needle is a hand-honed reverse cutting edge needle with a 19-mm needle length and 0.58-mm needle diameter.
Suture Removal Forces
This research was supported by a generous gift from the Texaco Philanthropic Foundation, White Plains, New York.
Adult New Zealand white rabbits (3-4 kg) were used in this study. Each animal was anesthetized with 1 mg/kg
Original Contributions presents articles of interest to both academic and practicing physicians. This section of JEM is coordinated bv. John A. Marx. MD. of Denver General Hosnital. I
RECEIVED: 8 May 1989; FINALSUBMISSION RECEIVED: 14 August 1989; ACCEPTED: 20 September, 1989 539
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S. Pham, G. T. Rodeheaver, M-C Dang, P. A. Foresman, J. C. Hwang, R. F. Edlich
acepromazine IM and 20 mg/kg ketamine hydrochloride IM. The dorsal skin was clipped with shears and then depilated. Using a template, 8 incision sites were marked on the paravertebral regions perpendicular to the spine; four incisions, measuring 4 cm long, were made on each side spaced 5 cm apart. The operative sites were first washed with an iodophor solution followed by 70% alcohol. Using aseptic technique, the incision was made with a No. 15 blade, extending down through the panniculus carnosus. Hemostasis was accomplished by applying gentle pressure with a gauze sponge. The incisions on one side were approximated by the 3-O continuous dermal nonabsorbable sutures; 5-O continuous dermal nonabsorbable sutures were used to close the incisions on the contralateral side. The type of suture employed in wound closure was randomly assigned. The needle entered the intact skin 1 cm proximal to the wound and exited through the apex of the incision. ‘Ihe continuous dermal suture closure was begun at the apex of the incision and passed through the cephalad dermal side of the wound; the exit point from the cephalad side of the wound was opposite the entrance on the dermal side, with no “backing tracking” of each bite (5). This continuous dermal suture closure was accomplished so that there were four bites on the cephalad side and four bites on the caudad side; each dermal bite was parallel to the skin edge. When the last dermal bite exited at the anterior end of the incision, it was passed beneath the intact skin to exit through the skin at a point 1 cm from the incision. The suture was pulled 2 cm in a posterior direction and then 4 cm in an anterior direction to ensure that the suture was not fixed in the tissue due to technical error. Sufficient tension was applied to suture ends to permit approximation of the wound edges, after which the suture was secured to the skin by microporous tapes. After wound closure, the wounds were covered by a sterile circumferential bandage. Each suture was employed to approximate 24 wounds. At designated time intervals (T,, immediately after closure, three days after closure, seven days after closure), the forces required to remove the continuous dermal sutures were recorded. The sutures were removed at a 0” angle from the suture exit point by first attaching the suture to a linearly driven load cell. This system recorded the force required to pull the suture through the tissue at a rate of 8.8 mL/min. The average force required to remove the suture was determined by dividing the area under the force distance curve by the distance. Suture Load Elongation Properties
Elongation of the sutures was measured on an Instron Universal Testing Instrument (Model No. 1122, Instron
Corp., Canton, MA). Suture samples were mounted in pneumatic clamps at a pressure of 60 pounds per square inch. The clamps were positioned to produce a gauge length of 50 mm and were extended during testing at a constant rate of 20 mm min. The load experienced by the suture was plotted continuously by a calibrated recorder, and the length of elongation was noted at 50-g increments up to 200 g. Eight new samples of each nonabsorbable suture were subjected to each load (50, 100, 150, 200 g). Percentage elongation was determined by dividing the length of the elongated suture by the original gauge length of 50 mm. The statistical significance of the data in the experimental studies was determined by Student’s t test.
RESULTS The most important determinants of the magnitude of the dermal suture removal forces are the suture material and the time of removal (Figures 1 and 2). Immediately after wound closure (T,), the mean suture removal forces for the 3-O and 5-O polypropylene sutures are significantly less than those for the other sutures (P < 0.05). Three days after wound closure, the suture removal forces for the 3-O polypropylene sutures are significantly less than those for the nylon sutures (P < 0.05) (Figure 1). At 3 and 7 days after wound closure, the removal forces for the 3-O polypropylene sutures are less than those for either the 3-O polybutester or 3-O polybutylene terephthalate, but these differences are not statistically different. For the 5-Omonofilament sutures, the suture removal forces for the nylon sutures are the greatest of the study. The suture removal forces for the 5-O nylon suture differs significantly from those of the polybutester and polybutylene terephthalate sutures three days after closure. As the time interval after wound closure increases, the magnitude of the suture removal forces decreases. Immediately after wound closure, the suture removal forces for the 3-O monofilament nonabsorbable sutures are significantly greater than those suture removal forces encountered with comparable size sutures 7 days after wound closure (P < 0.05). For the 5-O monofilament nylon, polybutester, and polybutylene terephthalate, the suture removal forces immediately after closure are significantly greater than those recorded 7 days later (P < 0.05). The suture removal forces for the 5-O polypropylene sutures immediately after closure are greater than those noted 7 days later, but these differences are not statistically significant. The size of suture material (3-O versus 5-O) does not significantly influence the magnitude of the suture removal forces at the different time intervals after wound closure.
OPOLYBUTYLENE TEREPHTHALATE I
Fiaure 1. The suture removal forces for continuous dermal3-0 nonabsorbable monofilament synthetic sutures at different time intervals after closure.
The load elongation properties of the sutures are influenced by the suture diameter and material (Figures 3 and 4). As expected, the larger diameter (3-O) sutures are more resistant to elongation than the small diameter sutures. The polybutester suture elongate under the lowest forces, followed by the polybutylene terephthalate sutures, and then the nylon sutures. The polypropylene sutures display the greatest resistance to elongation.
=NYLON lPOLYPROPYLENE UPOLYBUTESTER OPOLYI~UTYLENE TEREPHTHALATE
Flgure 2. The suture removal forces for continuous dermal CO nonabsorbable monofilament synthetic sutures at different time Intervals after closure.
In our studies, the forces required to remove polypropylene sutures from a continuous dermal closure are significantly less than those for nylon sutures, polybutester, and polybutylene terephthalate. These observations are consistent with those of other experimental as well as clinical studies. Mangus (6) observed that the forces needed to pull polypropylene sutures through a pig’s foot were significantly less than those encountered during passage of either silk or stainless steel sutures. Hopkinson and Bullen (7) had the subjective clinical impression that removal of dermal continuous polypropylene dermal sutures requires considerably less force than monofilament nylon sutures. This ease of removal of the polypropylene sutures is related to low coefficient of friction of its surface rather than to its load extension properties. We had hypothesized that suture elongation
S. Pham, G. T. Rodeheaver, M-C Dang, P. A. Foresman, J. C. Hwang, R. F. E&h
3 - 0 MONOFILAMENT 9
E 6?i 5g
Flgure 3. The load elongatlon properties of 3-g monofilament nonabsorbable sutures.
under low loads would reduce the diameter of the most extensible suture (polybutester) and thereby facilitate its removal. This hypothesis was not supported by our data, demonstrating that the suture with the greatest resistance to elongation (polypropylene) required the lowest forces
for suture removal. The extraction of monofilament nonabsorbable continuous dermal sutures can be facilitated by technical considerations. The continuous dermal suture should be surfaced as a percutaneous suture every 5 to 6 cm to
5 - 0 MONOFILAMENT 9
LNI LA TE
LOAD (g) Flgurs 4. The load elongatlon properties of 5-g monofllament nonabsorbable sutures.
Dermal Suture Removal
provide relatively short lengths of suture for easy extraction. A steady elastic pull over minutes to hours of the continuous dermal suture facilitates its removal and is accompanied by less discomfort than manual traction on the suture (3,6). In the emergency department, the continuous dermal (subcuticular) nonabsorbable suture can be used to approximate linear lacerations subjected to low static skin tensions. This method of closure is especially applicable to lacerations of the thin skin of the face and neck. If used on lacerations that are relatively short in length (< 5 cm), the continuous dermal suture does not have to surface through the epidermis to facilitate suture pull out. After dermal closure, tapes are applied to the wound to permit meticulous approximation of the epidermis. Moreover, these tapes provide additional wound closure support that allows early removal of the dermal suture before the 8th day after closure without disruption of the wound. Subsequently, the wound heals with an aesthetically pleasing scar without residual foreign body. When interrupted or continuous synthetic absorbable sutures are used for dermal closure, these buried sutures may
occasionally extrude through a skin sinus tract causing the patient to return to the emergency department for suture removal.
CONCLUSION The purpose of this study was to identify the synthetic nonabsorbable monofilament suture that required the lowest forces for removal of continuous dermal (subcutitular) sutures. Immediately after wound closure, polypropylene sutures required significantly lower suture removal forces than nylon, polybutester, and polybutylene terephthalate sutures. Within 7 days after wound closure, the suture removal forces markedly reduced for the continuous dermal nylon, polybutester, and polybutylene terephthalate to a level that was comparable to those encountered by the polypropylene suture. The ease of suture removal of polypropylene sutures from continuous dermal skin closure is related to its low surface coefficient of friction, rather than to its load elongation properties.
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19&7;164:230-6. 5. Straith RE, Lawson JM, Hipps CJ. The subcuticular suture. Postgrad Med. 1961;29:164-73. 6. Mangus DJ. Reversing the antilock braking system theory for suture removal. Plast Reconstr Surg. 1987;79:987-9. 7. Hopkinson GB, Bullen BR. Removable subcuticular skin suture in acute appendicitis: a prospective comparative clinical trial. Br Med J. 1982;284:869.