Multicenter Randomized Controlled Trial Comparing Early Versus Late Aquatic Therapy After Total Hip or Knee Arthroplasty

Multicenter Randomized Controlled Trial Comparing Early Versus Late Aquatic Therapy After Total Hip or Knee Arthroplasty

192 ORIGINAL ARTICLE Multicenter Randomized Controlled Trial Comparing Early Versus Late Aquatic Therapy After Total Hip or Knee Arthroplasty Thoral...

1MB Sizes 0 Downloads 30 Views

192

ORIGINAL ARTICLE

Multicenter Randomized Controlled Trial Comparing Early Versus Late Aquatic Therapy After Total Hip or Knee Arthroplasty Thoralf R. Liebs, MD, Wolfgang Herzberg, MD, Wolfgang Rüther, MD, PhD, Jörg Haasters, MD, PhD, Martin Russlies, MD, PhD, Joachim Hassenpflug, MD, PhD, on behalf of the Multicenter Arthroplasty Aftercare Project ABSTRACT. Liebs TR, Herzberg W, Rüther W, Haasters J, Russlies M, Hassenpflug J, on behalf of the Multicenter Arthroplasty Aftercare Project. Multicenter randomized controlled trial comparing early versus late aquatic therapy after total hip or knee arthroplasty. Arch Phys Med Rehabil 2012;93: 192-9. Objective: To evaluate if the timing of aquatic therapy influences clinical outcomes after total knee arthroplasty (TKA) or total hip arthroplasty (THA). Design: Multicenter randomized controlled trial with 3-, 6-, 12-, and 24-month follow-up. Setting: Two university hospitals, 1 municipal hospital, and 1 rural hospital. Participants: Patients (N⫽465) undergoing primary THA (n⫽280) or TKA (n⫽185): 156 men, 309 women. Intervention: Patients were randomly assigned to receive aquatic therapy (pool exercises aimed at training of proprioception, coordination, and strengthening) after 6 versus 14 days after THA or TKA. Main Outcome Measures: Primary outcome was self-reported physical function as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 3-, 6-, 12-, and 24-months postoperatively. Results were compared with published thresholds for minimal clinically important improvements. Secondary outcomes included the Medical Outcomes Study 36-Item Short-Form Health Survey, LequesneHip/Knee-Score, WOMAC-pain and stiffness scores, and patient satisfaction. Results: Baseline characteristics of the 2 groups were similar. Analyzing the total study population did not result in statistically significant differences at all follow-ups. However, when

From the Department of Orthopaedic Surgery, University of Schleswig-Holstein Medical Center, Kiel Campus, Kiel (Liebs, Hassenpflug); Department of Orthopaedic Surgery, Asklepios Westklinikum Hamburg, Hamburg (Herzberg); Department I of Orthopaedic Surgery, Ostseeklinik Damp, Damp (Haasters); Department of Orthopaedic Surgery, University of Schleswig-Holstein Medical Center, Lübeck Campus, Lübeck (Russlies); Department of Orthopaedic Surgery, Klinikum Bad Bramstedt, Bad Bramstedt (Rüther); and Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg (Rüther), Germany. Supported by the Society for Support of Research in and Fighting of Rheumatic Diseases Bad Bramstedt, registered society (Verein zur Förderung der Erforschung und Bekämpfung rheumatischer Erkrankungen, Bad Bramstedt e. V.) (grant no. vffr-35); the Society for Support of Rehabilitation Research in Schleswig-Holstein, registered society (vffr, Verein zur Förderung der Rehabilitationsforschung in Schleswig Holstein, e. V.) (grant no. 35); the State Insurance Agency of the Free and Hanseatic City of Hamburg (LVA Freie und Hansestadt Hamburg) (grant no. vffr-35); and the German Arthrosis Society, registered society (Deutsche Arthrose-Hilfe e.V.) (grant no. P37-A162). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. Reprint requests to Thoralf R. Liebs, MD, University of Schleswig-Holstein Medical Center, Campus Kiel, Department of Orthopaedic Surgery, Michaelisstr. 1, 24105 Kiel, Germany, e-mail: [email protected] 0003-9993/12/9302-00622$36.00/0 doi:10.1016/j.apmr.2011.09.011

Arch Phys Med Rehabil Vol 93, February 2012

performing subanalysis for THA and TKA, opposite effects of early aquatic therapy were seen between TKA and THA. After TKA all WOMAC subscales were superior in the early aquatic therapy group, with effect sizes of WOMAC physical function ranging from .22 to .39. After THA, however, all outcomes were superior in the late aquatic therapy group, with WOMAC effect sizes ranging from .01 to .19. However, the differences between treatment groups of these subanalyses were not statistically significant. Conclusions: Early start of aquatic therapy had contrary effects after TKA when compared with THA and it influenced clinical outcomes after TKA. Although the treatment differences did not achieve statistically significance, the effect size for early aquatic therapy after TKA had the same magnitude as the effect size of nonsteroidal anti-inflammatory drugs in the treatment of osteoarthritis of the knee. However, the results of this study do not support the use of early aquatic therapy after THA. The timing of physiotherapeutic interventions has to be clearly defined when conducting studies to evaluate the effect of physiotherapeutic interventions after TKA and THA. Key Words: Arthroplasty, replacement, hip; Arthroplasty, replacement, knee; Hydrotherapy; Randomized controlled trial [publication type]; Rehabilitation. © 2012 by the American Congress of Rehabilitation Medicine ESPITE THE WIDESPREAD use of total hip arthroplasty D (THA) and total knee arthroplasty (TKA), there is a notable lack of consensus regarding postoperative treatment. 1-4

Given the 2-to-10-fold global increase in the incidence of arthroplasty in the last 10 to 20 years, it has been emphasized that the evaluation of rehabilitation of this patient group should be a priority.5 In Europe, aquatic therapy, such as pool exercise, is commonly used in the aftercare of this patient group. Aquatic therapy, in general, has been reported to have a number of advantages6: the immersion in water relieves body-weight and allows patients to move their operated leg more easily, resulting in patients reporting a sense of pleasure while exercising in water.7 The viscous resistance of water protects the joint and

List of Abbreviations NSAID RCT SF-36 THA TJA TKA WOMAC

nonsteroidal anti-inflammatory drug randomized controlled trial Medical Outcomes Study 36-Item Short-Form Health Survey total hip arthroplasty total joint arthroplasty total knee arthroplasty Western Ontario and McMaster Universities Osteoarthritis Index

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs

leads to the development of increased muscular strength. By altering the movement velocity in water, different resistances can be achieved. The hydrostatic pressure supports reabsorption and gives the patient a sense of security while standing. Because pool exercises require continuous balance response, muscular coordination is improved.8 It has been argued that it may be “the combination of reduced gravity, hydrostatic force and warm water temperature”9(p4) that contributes to pain relief in the joints. In a Cochrane review of aquatic therapy for osteoarthritis and rheumatoid arthritis, it was concluded that the scientific evidence for aquatic therapy was weak due to methodologic quality of the studies identified, but that most of the studies demonstrated positive findings.10 To our knowledge, 4 studies have evaluated the effect of aquatic therapy after arthroplasty. One study demonstrated that aquatic therapy improved muscular coordination and strength after TKA, as measured by electromyographic mapping, isokinetics, and ultrasound.8 Another study found comparable outcomes, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), up to 6 months after TKA between a land-based versus a water-based rehabilitation protocol.5 Two other studies demonstrated improved patient reported outcomes, including the WOMAC, in patients who received aquatic therapy when compared with patients who received standard conventional gym treatment, after both THA11 and TKA.12 These authors wrote that “the hydrotherapy benefits after THA appear so evident that it is hard to conceive a lack of their early implementation in a rehabilitation protocol. . .”11(p94) However, in these studies it remained unclear as to how early aquatic therapy should be initiated. We are aware of no studies that have evaluated the effect of the timing of an aquatic therapy rehabilitation intervention after TKA or THA. Usually aquatic therapy is started after wound healing, that is, not before the 14th postoperative day. We hypothesized that by starting the aquatic therapy earlier, the reported beneficial effects of aquatic therapy would improve the clinical outcome, as measured by the WOMAC physical function scale. For this reason we randomized patients into early versus late aquatic therapy, to evaluate if the timing of aquatic therapy influences patients’ health-related quality of life and patient satisfaction after hip and knee arthroplasty. Early aquatic therapy in this context was defined as starting on postoperative day 6, while late aquatic therapy was defined as starting as before, that is, on postoperative day 14. METHODS We conducted a multicenter randomized controlled trial (RCT) comparing the clinical outcomes of patients who had been randomly assigned to receive aquatic therapy after 6 versus 14 days after THA or TKA. The study protocol was approved by the local ethics committee, and all participants provided written informed consent prior to participation in this study. A data and safety monitoring board monitored the study. Participants All patients who were scheduled to receive unilateral hip or knee replacement surgery at participating centers on an elective basis after diagnosis of osteoarthritis were candidates for inclusion in the study between August 16, 2003 and December 31, 2004. Exclusion criteria were: (1) a history of septic arthritis, (2) hip or knee fracture, (3) intraoperative complications, (4) revision arthroplasty, (5) rheumatoid arthritis, (6) amputations, (7) malignancy, and (8) inability to complete the questionnaires because of cognitive or language difficulties.

193

Information about the study was handed out to participants on the day of admission to the hospital. Eligible patients were identified by the admitting physicians and were approached to participate in the trial by either the admitting physician or a study coordinator. Patients providing written informed consent were then enrolled in the trial. Participating centers are all located in the northernmost state of Germany. These are 2 orthopedic departments of university hospitals, 1 department of surgery at a municipal hospital, and 1 department of orthopedics at a rural hospital. Randomization Scheme All patients had an equal probability of assignment to the groups. External randomization was achieved by means of computer-generated lists (Microsoft Excela) in blocks of 20, stratified by participating hospital. At the time of enrollment of each participant, the coordinating center was notified via telefax, where the study nurse added them to the list in sequential order. After surgery, the result of the randomization was faxed back to the participating hospital, thereby avoiding that the study participants or surgeon knew of the randomization results beforehand (allocation concealment).13 The method of generation of the randomization lists was unknown to the participating hospitals. Due to the nature of the intervention, blinding of the study participants and physiotherapists was not possible. Intervention Participants were randomized into 2 groups: 1 group received aquatic therapy as pool exercise after the completion of wound healing on the 14th postoperative day, while the other group received this aquatic therapy beginning on the 6th postoperative day with the wound covered with a waterproof adhesive dressing (Op-Siteb). In both groups the aquatic therapy was performed for 30 minutes for 3 times a week up to the 5th postoperative week. In both groups the pool exercises aimed at training of proprioception, coordination, and strengthening, with the aid of float cuffs, training kickboards, and bar floats.8 Apart from the interventions, both groups participated in a standard postsurgery program of daily physiotherapy, consisting of range of motion activities, exercises for improvement of muscle tension, venous return, balance, coordination and gait, and instruction in activities of daily living, including transfers, walking, and negotiation of stairs and uneven surfaces. In patients with knee replacement surgery, continuous passive motion machines were used on a daily basis after removal of suction drains. All patients were given analgesics according to a standard scheme. Special attention was given so that all therapies, with the exception of the timing of aquatic therapy, were not affected by the study. At the beginning of the study, all hospital physiotherapists were informed in detail about the study. Outcomes The primary outcome was self-reported physical function 3-, 6-, 12-, and 24-months postoperatively. This was measured by means of the WOMAC,14 using a validated translated version.15 Secondary outcomes consisted of leg specific stiffness and pain, both measured by the WOMAC; the physical component summary of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36),16,17 the Lequesne-Hip/Knee-Score,18 and a question on patient satisfaction.19 For the WOMAC, responses were recorded on a visual analog scale with terminal descriptors. Scores were added for each category and standardized to a score of 0 to 100, with Arch Phys Med Rehabil Vol 93, February 2012

194

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs

Fig 1. Consolidated Standards of Reporting Trials participant flow chart. Abbreviations: BKA, below knee amputation; CVA, cerebrovascular accident; F-U, follow-up; POD, postoperative day.

higher scores indicating more pain, more stiffness, or more dysfunction. All patients were asked to answer the questionnaire at the time of hospital admission. During hospital stay, the study nurse visited the patient to ensure that the questionnaire was filled in completely. After 3, 6, 12, and 24 months, participants were mailed a questionnaire with a prepaid return envelope. Nonresponding participants were reminded by mail up to 3 times at intervals of 2 weeks. Participants still not responding were contacted by telephone to determine the reason for not responding. Data were entered into a database (Microsoft Accessa) at the coordinating center. There were no changes to trial outcomes after the trial commenced. Minimal Clinically Important Improvements The interpretation of the results of RCTs has emphasized statistical significance rather than clinical importance.20 The lack of emphasis on clinical importance has been reported to lead to frequent misconceptions and disagreement regarding the interpretation of the results of clinical trials and a tendency Arch Phys Med Rehabil Vol 93, February 2012

to equate statistical significance with clinical importance.20 In some instances, statistically significant results may not be clinically important and, conversely, statistically insignificant results do not rule out completely the possibility of clinically important effects.20 To allow readers to interpret the clinical importance of trial results from their own perspective, the concept of the minimal clinically important difference has been introduced.20 The minimal clinically important difference is defined as the “smallest treatment effect that would result in a change in patient management, given its side effects, costs and inconveniences.”20(p1197) To assess whether the statistical significant differences observed in the present study represent clinically meaningful change, we compared the observed differences of the primary outcome to previously published thresholds for the minimal clinically important improvements that were stratified to the severity of the disease.21 These thresholds are 5.3 WOMAC function units for knee osteoarthritis, stratified for a WOMAC function score of 35.3

195

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs Table 1: Baseline Characteristics Hip Arthroplasty

Characteristic

Age (y) Body mass index* Sex ratio (men:women) WOMAC physical function score† WOMAC pain score† WOMAC stiffness score† SF-36, physical component summary‡ SF-36, mental component summary‡ Lequesne-Hip/Knee-Score§ Number of comorbidities None One Two or more Additional limitation due to Contralateral same great joint Ipsilateral adjacent great joint Contralateral adjacent great joint Low back pain Upper extremities Feet Diagnosis Osteoarthritis Femoral head necrosis/Ahlbäck’s disease

Knee Arthroplasty

Early Aquatic Therapy (n⫽138)

Late Aquatic Therapy (n⫽142)

Early Aquatic Therapy (n⫽87)

Late Aquatic Therapy (n⫽98)

66.7⫾10.3 27.6⫾4.4 50:88 57.3⫾21.4 54.8⫾23.2 57.7⫾25.6 28.1⫾6.7 47.7⫾12.5 11.9⫾3.2

69.1⫾9.8 26.8⫾4.6 54:88 54.8⫾22.7 52.4⫾25.1 52.0⫾27.6 26.8⫾8.2 50.4⫾11.4 11.6⫾3.1

68.5⫾8.6 29.3⫾5.0 26:61 53.1⫾24.8 53.1⫾24.8 51.4⫾31.7 29.0⫾7.9 49.4⫾12.0 11.0⫾3.1

70.9⫾7.5 29.3⫾4.6 26:72 50.2⫾24.4 50.2⫾24.6 48.6⫾31.5 28.5⫾6.5 46.9⫾12.6 11.4⫾3.0

15 (51.7%) 45 (48.9%) 78 (49.1%)

14 (48.3%) 47 (51.1%) 81 (50.9%)

10 (38.5%) 18 (43.9%) 59 (50.0%)

16 (61.5%) 23 (56.1%) 59 (50.0%)

33 (55.9%) 22 (40.7%) 17 (45.9%) 53 (49.5%) 6 (30.0%) 10 (47.6%)

26 (44.1%) 32 (59.3%) 20 (54.1%) 54 (50.5%) 14 (70.0%) 11 (52.4%)

32 (42.1%) 7 (53.8%) 3 (60.0%) 35 (53.0%) 9 (40.9%) 11 (64.7%)

44 (57.9%) 6 (46.2%) 2 (40.0%) 31 (47.0%) 13 (59.1%) 6 (35.3%)

131 (49.1%) 7 (53.8%)

136 (50.9%) 6 (46.2%)

86 (47.3%) 1 (NA)

96 (52.7%) 2 (NA)

NOTE. Values are mean ⫾ SD or as otherwise indicated. Abbreviation: NA, not applicable. *Body mass index is the weight in kilograms divided by the square of the height in meters. † Range from 0 to 100 with lower scores representing better quality of life. ‡ Higher scores representing better quality of life. § Lower scores representing better quality of life.

or less; and 2.6 WOMAC function units for hip osteoarthritis, stratified for a WOMAC function score of 38.2 or less.21 Power Analysis For the power analysis we chose an effect size d of .30, and a significance level of .05. Based on the .80 power to detect a significant difference (P⫽.05, 2-sided), 176 patients were required for each study group. Because we expected a loss to follow-up of about 25% to 30%, we increased the number of recruited patients accordingly. Because it was unknown whether the effect of the timing of aquatic therapy would differ between patients with knee and hip arthroplasty, we prespecified separate analyses for these groups. Statistical Analysis All analyses were conducted according to the intention-to-treat principle. Baseline data were examined for differences. Continuous follow-up data were initially tested for normative distribution with the Kolmogorov-Smirnov test. Because many of them deviated from such a pattern, the nonparametric Mann-Whitney U test was used to determine differences between groups. Categorical data (patient satisfaction) were compared using chi-square tests. All P values are 2-tailed; no corrections were made for multiple comparisons. Effect sizes d,22 as the standardized differences between 2 groups, were calculated as described by Cohen.23 Statistical analysis was performed using SPSS.c

RESULTS Participants In total, 502 patients were candidates for participation in the study. Of these, a total of 465 underwent randomization. The recruitment process and participant flow, including losses and exclusions after randomization, are outlined in figure 1. No statistically significant pretreatment differences existed among the study groups (table 1), suggesting that the randomization procedures produced well balanced and comparable groups at baseline. Overall, 417 patients completed the postal questionnaire at 3 months, resulting in a follow-up rate of 90%. The follow-up rate dropped to 85% at 6-month, 79% at 12-month, and to 74% at 24-month follow-up. There was no significant association between patients who did not respond to the follow-up questionnaire and patient baseline characteristics. Follow-Up (Hip Arthroplasty) After hip arthroplasty, all mean WOMAC subscales at all follow-up intervals were better in the group starting aquatic therapy after wound-healing. This effect was not statistically significant for any of the outcomes at any time, however (table 2). The effect sizes for the primary outcome ranged from .01 (3-mo follow-up, absolute difference⫽.30; P⫽.80) to .19 (6-mo follow-up, absolute difference⫽3.1; P⫽.52). Using the SF-36, the Lequesne-Hip/Knee-Score, and patient satisfaction, Arch Phys Med Rehabil Vol 93, February 2012

196

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs Table 2: Outcomes 3, 6, 12, and 24 Months After Total Joint Arthroplasty Hip Arthroplasty

Characteristic

WOMAC function score* 3-mo F/U 6-mo F/U 12-mo F/U 24-mo F/U WOMAC pain score* 3-mo F/U 6-mo F/U 12-mo F/U 24-mo F/U WOMAC stiffness score* 3-mo F/U 6-mo F/U 12-mo F/U 24-mo F/U SF-36, PCS† 3-mo F/U 6-mo F/U 12-mo F/U 24-mo F/U Lequesne-Hip/Knee-Score‡ 3-mo F/U 6-mo F/U 12-mo F/U 24-mo F/U

Early Aquatic Therapy

SE

Late Aquatic Therapy

SE

21.2⫾18.9 19.0⫾19.1 17.1⫾19.5 15.6⫾18.1

1.8 1.9 1.9 1.8

20.9⫾17.9 15.9⫾14.4 15.5⫾16.0 14.1⫾14.5

13.7⫾15.3 14.0⫾18.2 13.1⫾19.2 12.2⫾17.2

1.4 1.8 1.9 1.7

27.1⫾22.3 24.0⫾23.4 23.1⫾25.0 20.8⫾23.4

Knee Arthroplasty

P

Effect Size (d)

Early Aquatic Therapy

SE

Late Aquatic Therapy

SE

P

Effect Size (d)

1.6 1.3 1.5 1.4

.798 .520 .923 .825

0.01 0.19 0.09 0.09

21.9⫾19.4 18.2⫾15.1 17.1⫾16.7 13.8⫾13.6

2.2 1.8 2.1 1.7

26.8⫾20.7 22.1⫾21.1 21.4⫾21.3 20.7⫾21.3

2.3 2.4 2.5 2.6

.098 .453 .291 .117

0.24 0.22 0.22 0.39

13.1⫾14.6 10.1⫾12.3 10.4⫾15.1 9.9⫾14.4

1.3 1.1 1.4 1.4

.926 .498 .582 .839

0.04 0.25 0.16 0.15

20.1⫾20.0 14.7⫾14.9 13.2⫾15.0 9.6⫾11.9

2.3 1.7 1.8 1.5

22.5⫾21.7 18.0⫾20.1 17.4⫾22.4 15.2⫾19.2

2.3 2.2 2.6 2.3

.390 .423 .334 .097

0.12 0.19 0.22 0.35

2.1 2.3 2.6 2.3

25.2⫾22.8 22.4⫾19.9 19.4⫾20.1 16.9⫾18.2

2.2 1.8 1.9 1.7

.450 .964 .589 .552

0.08 0.08 0.16 0.19

29.6⫾25.0 23.6⫾21.4 25.4⫾24.1 15.2⫾14.1

2.9 2.5 2.9 1.7

31.4⫾25.1 25.9⫾26.5 24.6⫾24.2 20.4⫾21.7

2.7 2.9 2.8 2.6

.522 .854 .871 .347

0.07 0.09 0.03 0.28

38.6⫾10.4 43.4⫾10.1 43.9⫾10.7 45.1⫾11.1

1.0 1.0 1.1 1.1

39.3⫾9.7 43.0⫾9.9 44.9⫾9.4 45.2⫾9.7

0.9 0.9 0.9 0.9

.447 .791 .697 .808

0.07 0.05 0.10 0.01

37.8⫾8.0 40.1⫾8.6 42.0⫾8.9 43.9⫾9.4

0.9 1.0 1.1 1.2

36.0⫾8.2 39.9⫾9.1 40.9⫾9.9 41.0⫾9.7

0.9 1.0 1.2 1.2

.108 .954 .495 .131

0.21 0.02 0.12 0.31

7.9⫾4.3 6.7⫾4.0 6.6⫾4.4 5.6⫾3.8

0.4 0.4 0.4 0.4

7.9⫾4.1 6.8⫾3.9 6.0⫾3.9 5.8⫾4.2

0.4 0.4 0.4 0.4

.979 .911 .357 .909

0.00 0.02 0.16 0.04

9.1⫾3.3 8.1⫾3.8 7.3⫾3.5 6.8⫾3.8

0.4 0.4 0.4 0.5

9.8⫾3.6 8.4⫾4.0 8.2⫾4.2 7.4⫾3.8

0.4 0.4 0.5 0.5

.315 .618 .243 .361

0.20 0.08 0.24 0.15

NOTE. Data are mean ⫾ SD unless otherwise indicated. All P values are based on the Mann-Whitney U test. Abbreviations: PCS, Physical Component Summary; F/U, follow-up. *Range from 0 to 100 with lower scores representing better quality of life. † Higher scores representing better quality of life. ‡ Lower scores representing better quality of life.

no differences could be detected between study groups at all follow-up intervals (see tables 2 and 3, figs 2 and 3). Follow-Up (Knee Arthroplasty) After knee arthroplasty, however, all mean outcomes were better in the early aquatic therapy group at 3-, 6-, 12-, and 24-month follow-up. The only exception to this finding was a slightly better WOMAC stiffness score for the late aquatic therapy group at 12-month follow-up (effect size⫽.03). All these effects were not statistically significant, however (see tables 2 and 3, figs 2 and 3). The effect sizes for the primary outcome WOMAC physical function ranged from .22 at 6-month follow-up (absolute difference⫽3.9; P⫽.45) to .39 at 24-month follow-up (absolute difference⫽6.9; P⫽.12). Adverse Effects After knee arthroplasty, 5 patients of the early aquatic therapy group (because of limited range of motion of knee [n⫽2], intraarticular effusion of knee, diabetes, cerebrovascular accident) and 1 of the late aquatic therapy group (because of limited range of motion of knee) were readmitted to the hospital within 3 months. Of these, the first 3 of the early aquatic therapy group and 1 of the late aquatic therapy group could be directly or indirectly related to the intervention. After hip arthroplasty, 10 patients of the early aquatic therapy group (because of dislocation of hip, wound dehiscence, thrombosis [n⫽2], intestinal perforation, shunt revision, superArch Phys Med Rehabil Vol 93, February 2012

vision after fall, abscess, appendicitis, pneumonia) and 4 of the late aquatic therapy group (because of dislocation of hip, wound dehiscence, pulmonary embolism, pulmonary edema) were readmitted to the hospital within 3 months. Of these, the first 2 adverse effects of the early aquatic therapy group and the first 2 of the late aquatic therapy group could be directly or indirectly related to the intervention. DISCUSSION This is the first study, to our knowledge, to examine the influence of the timing of a single rehabilitation intervention, here the timing of aquatic therapy after hip and knee joint replacement surgery, on physical function, pain, joint stiffness, and quality of life. These dimensions of health-related quality of life are recommended as a rationale for the implementation of the most adequate standard of care.24 This randomized study showed that the use of early aquatic therapy has opposite effects in terms of health-related quality of life after THA when compared with TKA. After TKA, early aquatic therapy led to clinically important improved patient outcomes when compared with late aquatic therapy. After hip arthroplasty, on the other hand, the results of this study indicate that early aquatic therapy should be avoided. In addressing the clinical importance, commonly comparing effect sizes25 is recommended, especially in systematic reviews and meta-analyses.26,27 The effect sizes of the primary outcome for our intervention ranged from .01 to .19 after hip arthroplasty and ranged from .22 to .39 for knee arthroplasty. There-

197

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs Table 3: Patient Satisfaction by Timing of Aquatic Therapy Hip Arthroplasty

Characteristic

Early Aquatic Therapy n (%)

Late Aquatic Therapy n (%)

Patient satisfaction* 3-Month F/U 6-Month F/U 12-Month F/U 24-Month F/U

95 (85%) 92 (84%) 88 (88%) 88 (88%)

107 (82%) 112 (90%) 105 (88%) 97 (88%)

Knee Arthroplasty

Relative Risk†

95% Confidence Interval

0.798 1.686 1.023 1.017

0.40–1.57 0.78–3.62 0.79–2.35 0.44–2.35

P

Early Aquatic Therapy n (%)

Late Aquatic Therapy n (%)

Relative Risk

95% Confidence Interval

P

.514 .178 .957 .968

55 (71%) 58 (77%) 52 (75%) 51 (77%)

61 (70%) 61 (73%) 54 (72%) 51 (74%)

0.938 0.813 0.841 0.833

0.48–1.84 0.39–1.68 0.40–1.77 0.38–1.83

.854 .576 .613 .840

Abbreviation: F/U, follow-up. *Percentage of patients that answered very satisfied to the question “How satisfied are you with the results of your joint replacement surgery?” Other possible answers were: somewhat satisfied, somewhat dissatisfied, very dissatisfied. † The relative risk of answering “very satisfied” when late aquatic therapy had been performed.

fore, these effect sizes for the intervention are rather consistent after knee arthroplasty, but inconsistent after hip arthroplasty. The effect sizes after knee arthroplasty exceeded the pooled effect size of .20 that was obtained from a meta-analysis of randomized placebo controlled trials for reduction in functional disability by nonsteroidal anti-inflammatory drugs (NSAIDs) in osteoarthritis of the knee.28 Therefore, the effect size of early aquatic therapy after knee arthroplasty is in the same range as the effect size of NSAIDs in osteoarthritis of the knee. The clinical importance of our findings is supported by the concept of the minimal clinically important improvements,21 because the published specific threshold of 5.3 WOMAC function units for the primary outcome is exceeded in our study (6.9 WOMAC function units at 24-mo follow-up). As baseline data showed that patients were homogeneous between the groups, there is no evidence that factors other than the timing of aquatic therapy could have influenced the outcomes. However, several patients after THA were randomized to early aquatic therapy, but did not receive early aquatic therapy for various patient specific reasons. This noncompliance with assigned therapy may mean that the conducted intention-to-treat analysis underestimates the real treatment effect.22 According to a recent review,24 age, sex, operated joint, primary or revision surgery, comorbidities, and baseline characteristics are known to influence the health-related quality of life after total joint arthroplasty (TJA). All these factors cannot be influenced by the physician. On the other hand, studies in which patients were randomized to different prosthetic types have failed to demonstrate a significant effect of different surgical procedures on health-related quality of life.24 Also, there appears to be no effect of inpatient compared with homebased rehabilitation.29 Recently, an association of hospital and surgeon procedure volume with patient centered outcomes has been described.30 Therefore, this is one of the few studies demonstrating a clinically important effect on the health-related quality of life after TKA by a factor that can be influenced by health care professionals, apart from procedure volume. Looking at these findings, it should be noted that the intervention was simple to administer, requiring only limited extra input from health care professionals. We chose 3 and 6 months as the appropriate study interval because the most improvement in postoperative physical health takes place during this time.24 We added a 12- and 24-month study interval to standardize our research with that of other authors who have analyzed health-related quality of life after TJA.24 Similarly to other studies concerned with health-related

quality of life,24 the current study was not designed to analyze long-term implant failure. This issue has been extensively addressed previously.31 We hypothesize that the weak effect of the timing of aquatic therapy after THA is due to the ceiling effect of that procedure, with a high rate of patient satisfaction and improvement of health-related quality of life due to THA alone, thereby leaving only a limited space for improvement by additional interventions. After TKA, on the other hand, a significantly higher number of patients is not satisfied,32 leaving room for the effect of additional interventions. We assume that, apart from the known advantages of aquatic therapy, the hydrostatic force of water immersion reduces effusion of the operated knee joint. Because the joint capsule is closed after TKA, the reduction of effusion leads to less pain inhibition, and leading to an advantage in functional recovery. As the joint capsule is not closed during THA, this mechanism does not apply to THA. The present study has several strengths. It is an RCT in a multicenter setting, performed at university, rural, and municipal hospitals, ensuring a high external validity. Furthermore, this setting provided a broader coverage of surgical experience levels when compared with a mono-center study. We also used the WOMAC as the primary outcome score, which is recommended in this setting.1 Study Limitations Although the study has several strengths, there are limitations. First, we conducted separate analysis of knee and hip arthroplasty, because it was unknown beforehand if the effect of the intervention would differ between these patient groups. These separate analyses, however, resulted in a smaller number of patients for the subanalyses with the subanalyses being underpowered. These underpowered subanalyses have increased probability of failing to demonstrate statistically significant differences, as in our study. Second, while this study has a 90% follow-up rate at 3 months and 85% at 6 months, the follow-up rate dropped to 79% at 12 months and to 74% at 24 months. Because the results of the 24-month follow-up are quite similar to the results of the 3 earlier follow-ups, it appears unlikely that a more complete 24-month follow-up would have altered the study result. Third, although the eligibility criteria were fairly broad, the trial was restricted to patients undergoing unilateral primary total joint replacement. Therefore, our results cannot be transferred to patients undergoing revision or bilateral total joint replacement. Arch Phys Med Rehabil Vol 93, February 2012

198

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs

WOMAC Physical Function by Timing of Aquatic Therapy 0

10 WOMAC Physical function

p =0·798 ES=0·01

p =0·520 ES=0·19

p =0·825 ES=0·09

p =0·923 ES=0·09

20 p =0·453 ES=0·22

30

p =0·117 ES=0·39

p =0·291 ES=0·22

p =0·098 ES=0·24

40

THA: early hydrotherapy 50

THA: late hydrotherapy TKA: early hydrotherapy

60 TKA: late hydrotherapy 70 baseline

3 month F/U

6 month F/U

12 month F/U

24 month F/U

Fourth, in our study the study nurse visited the patient after randomization to ensure that the questionnaire was filled in completely. Because this study nurse also handled the randomization lists, it could be argued that the nurse as an outcome assessor was not blinded to the randomization result. However, given the large number of patients involved in the study it is unlikely that the nurse remembered the randomization status when checking the preoperative questionnaire for completeness. In addition, in most cases the number of questions not already filled in by the participant was very small, leaving only limited room for the study nurse to possibly influence the questionnaire result. Besides, by this mechanism the nurse could have only affected the baseline measure. The study nurse could not have influenced the postoperative outcome, because a mail-in questionnaire was used for that purpose. Moreover, the nurse was not aware of which questions were to be used as an outcome

Fig 2. Physical function as measured with the WOMAC 3, 6, 12, and 24 months after early versus late aquatic therapy. Vertical bars represent SE. Abbreviations: ES, effect size; F/U, follow-up.

measure. The calculation of outcomes measures was performed by the authors. Therefore, it appears unlikely that the nurse as an outcome assessor could have influenced the study results. Fifth, we have compared early versus late beginning of aquatic therapy after TKA and THA. We did not compare aquatic therapy with no aquatic therapy or other types of physical therapy for a number of reasons: beneficial effects of aquatic therapy have been reported in three8,11,12 of the four reports5,8,11,12 dealing with aquatic therapy after TKA or THA. Withholding a group from aquatic therapy could lead to an unacceptable reduction of compliance, because patients in our country expect aquatic therapy after total joint arthroplasty. For this reason we randomized patients to early versus late aquatic therapy, assuming that the beneficial effects of aquatic therapy would improve the clinical outcome if started sooner after surgery.

Patient Satisfaction by Timing of Aquatic Therapy

Fig 3. Patient satisfaction 3, 6, 12, and 24 months after early versus late aquatic therapy. Abbreviation: F/U, follow-up. *RR: relative risk (95% confidence interval). † Percentage of participants who answered “very satisfied” to the question: “How satisfied are you with the results of your joint replacement surgery?” (very satisfied, somewhat satisfied, somewhat dissatisfied, very dissatisfied).

Percentage of "very satisfied" patients†

1

0,9

p =0·178 RR=1·686 (0·78-3·62)* p =0·514 RR=0·798 (0·40-1·57)*

p =0·957 RR=1·023 (0·79-2·35)*

p =0·968 RR=1·017 (0·44-2·35)*

0,8

0,7

p =0·576 p =0·854 RR=0·813 (0·39-1·68)* RR=0·938 (0·48-1·84)*

p =0·613 RR=0·841 (0·40-1·77)*

p =0·840 RR=0·833 (0·38-1·83)*

0,6 Total Hip Arthroplasty: Early hydrotherapy 0,5 Total Hip Arthroplasty: Late hydrotherapy Total Knee Arthroplasty: Early hydrotherapy

0,4

Total Knee Arthroplasty: Late hydrotherapy 0,3 3-Month F/U

Arch Phys Med Rehabil Vol 93, February 2012

6-Month F/U

12-Month F/U

24-Month F/U

AQUATIC THERAPY AFTER TOTAL HIP OR KNEE ARTHROPLASTY, Liebs

CONCLUSIONS The present study demonstrates that the timing of physiotherapy measures, such as aquatic therapy, has clinically relevant effects after knee arthroplasty. Although not statistically significant, the effect size of the timing of the intervention is clinically relevant after knee arthroplasty because it is in the same range as NSAIDs in the treatment of osteoarthritis of the knee. However, the results of this study do not support the use of early administration of aquatic therapy after hip arthroplasty. Therefore, further research is warranted to identify the optimal time frame for the start of aquatic therapy after TKA in order to exploit the potential of aquatic therapy for improving clinical outcome after TKA. Most importantly, however, this study demonstrates that the timing of physiotherapeutic interventions has opposite effects after TKA when compared with THA and therefore the timing of physiotherapeutic interventions has to be carefully planned if studies are performed to evaluate the effect of physiotherapeutic rehabilitation after TKA and THA. References 1. NIH Consensus Statement on Total Knee Replacement. NIH Consens State Sci Statements 2003;20:1-32. 2. Enloe LJ, Shields RK, Smith K, Leo K, Miller B. Total hip and knee replacement treatment programs: a report using consensus. J Orthop Sports Phys Ther 1996;23:3-11. 3. Duggal N. Improving orthopedic outcomes: focus on rehabilitation. Orthopedics 2007;30:339, 341. 4. Youm T, Maurer SG, Stuchin SA. Postoperative management after total hip and knee arthroplasty. J Arthroplasty 2005;20: 322-4. 5. Harmer AR, Naylor JM, Crosbie J, Russell T. Land-based versus water-based rehabilitation following total knee replacement: a randomized, single-blind trial. Arthritis Rheum 2009;61:184-91. 6. Ahlqvist J. Hydrotherapy has had and has a rationale. Rheumatology (Oxford) 2002;41:1070-1. 7. Mannerkorpi K, Nyberg B, Ahlmen M, Ekdahl C. Pool exercise combined with an education program for patients with fibromyalgia syndrome. A prospective, randomized study. J Rheumatol 2000;27:2473-81. 8. Erler K, Anders C, Fehlberg G, Neumann U, Brucker L, Scholle HC. [Objective assessment of results of special hydrotherapy in inpatient rehabilitation following knee prosthesis implantation] [German]. Z Orthop Ihre Grenzgeb 2001;139:352-8. 9. Cochrane T, Davey RC, Matthes Edwards SM. Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis. Health Technol Assess 2005;9:iii-xi, 1-114. 10. Verhagen AP, de Vet HC, de Bie RA, Kessels AG, Boers M, Knipschild PG. Balneotherapy for rheumatoid arthritis and osteoarthritis. Cochrane Database Syst Rev 2000;(2):CD000518. 11. Giaquinto S, Ciotola E, Dall’armi V, Margutti F. Hydrotherapy after total hip arthroplasty: a follow-up study. Arch Gerontol Geriatr 2010;50:92-5. 12. Giaquinto S, Ciotola E, Dall’armi V, Margutti F. Hydrotherapy after total knee arthroplasty. A follow-up study. Arch Gerontol Geriatr 2010;51:59-63. 13. Moher D, Schulz KF, Altman DG. The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomised trials. Lancet 2001;357:1191-4. 14. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol 1988;15:1833-40. 15. Stucki G, Meier D, Stucki S, et al. [Evaluation of a German version of WOMAC (Western Ontario and McMaster Universities) Arthrosis Index] [German]. Z Rheumatol 1996;55:40-9.

199

16. Bullinger M. German translation and psychometric testing of the SF-36 Health Survey: preliminary results from the IQOLA Project. International Quality of Life Assessment. Soc Sci Med 1995; 41:1359-66. 17. Ware JE Jr, Kosinski M, Bayliss MS, McHorney CA, Rogers WH, Raczek A. Comparison of methods for the scoring and statistical analysis of SF-36 health profile and summary measures: summary of results from the Medical Outcomes Study. Med Care 1995;33(4 Suppl):AS264-79. 18. Lequesne MG, Mery C, Samson M, Gerard P. Indexes of severity for osteoarthritis of the hip and knee. Validation⫺value in comparison with other assessment tests. Scand J Rheumatol Suppl 1987;65:85-9. 19. Katz JN, Phillips CB, Poss R, et al. The validity and reliability of a Total Hip Arthroplasty Outcome Evaluation Questionnaire. J Bone Joint Surg Am 1995;77:1528-34. 20. Chan KB, Man-Son-Hing M, Molnar FJ, Laupacis A. How well is the clinical importance of study results reported? An assessment of randomized controlled trials. CMAJ 2001;165:1197-202. 21. Tubach F, Ravaud P, Baron G, et al. Evaluation of clinically relevant changes in patient reported outcomes in knee and hip osteoarthritis: the minimal clinically important improvement. Ann Rheum Dis 2005;64:29-33. 22. Altman DG, Schulz KF, Moher D, et al. The revised CONSORT statement for reporting randomized trials: explanation and elaboration. Ann Intern Med 2001;134:663-94. 23. Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. Hillsdale: Lawrence Erlbaum Associates; 1988. 24. Ethgen O, Bruyère O, Richy F, Dardennes C, Reginster JY. Health-related quality of life in total hip and total knee arthroplasty. A qualitative and systematic review of the literature. J Bone Joint Surg Am 2004;86-A:963-74. 25. Matthews JN, Altman DG. Statistics notes. Interaction 2: compare effect sizes not P values. BMJ 1996;313:808. 26. Liberati A, Altman DG, Tetzlaff J, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration. BMJ 2009;339:b2700. 27. Moher D, Cook DJ, Eastwood S, Olkin I, Rennie D, Stroup DF. Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement. Quality of Reporting of Meta-analyses. Lancet 1999;354:1896-900. 28. Bjordal JM, Ljunggren AE, Klovning A, Slordal L. Non-steroidal anti-inflammatory drugs, including cyclo-oxygenase-2 inhibitors, in osteoarthritic knee pain: meta-analysis of randomised placebo controlled trials. BMJ 2004;329:1317. 29. Mahomed NN, Davis AM, Hawker G, et al. Inpatient compared with home-based rehabilitation following primary unilateral total hip or knee replacement: a randomized controlled trial. J Bone Joint Surg Am 2008;90:1673-80. 30. Katz JN, Mahomed NN, Baron JA, et al. Association of hospital and surgeon procedure volume with patient-centered outcomes of total knee replacement in a population-based cohort of patients age 65 years and older. Arthritis Rheum 2007;56:568-74. 31. Finerman GA, Dorey FJ, Grigoris P, McKellop HA. Total hip arthroplasty outcomes. Secaucus: Churchill Livingstone; 1998. 32. Ranawat CS, Ranawat AS, Mehta A. Total knee arthroplasty rehabilitation protocol: what makes the difference? J Arthroplasty 2003;18(3 Suppl 1):27-30. Suppliers a. Microsoft Inc, One Microsoft Way, Redmond, WA 98052. b. Smith & Nephew, 15 Adam St, London WC2N 6LA, UK. c. SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.

Arch Phys Med Rehabil Vol 93, February 2012