Stiffness After Total Knee Arthroplasty

Transcription

1 Stiffness After Total Knee Arthroplasty Matthew R. Bong, MD, and Paul E. Di Cesare, MD Abstract Postoperative stiffness is a debilitating complication of total knee arthroplasty. Preoperative risk factors include limited range of motion, underlying diagnosis, and history of prior surgery. Intraoperative factors include improper flexion-extension gap balancing, oversizing or malpositioning of components, inadequate femoral or tibial resection, excessive joint line elevation, creation of an anterior tibial slope, and inadequate resection of posterior osteophytes. Postoperative factors include poor patient motivation, arthrofibrosis, infection, complex regional pain syndrome, and heterotopic ossification. The first steps in treating stiffness are mobilizing the patient and instituting physical therapy. If these interventions fail, options include manipulation, lysis of adhesions, and revision arthroplasty. Closed manipulation is most successful within the first 3 months after total knee arthroplasty. Arthroscopic or modified open lysis of adhesions can be considered after 3 months. Revision arthroplasty is preferred for stiffness from malpositioned or oversized components. Patients who initially achieve adequate range of motion (>90 of flexion) but subsequently develop stiffness more than 3 months after surgery should be assessed for intrinsic as well as extrinsic causes. J Am Acad Orthop Surg 2004;12: Total knee arthroplasty (TKA) has proved to be a highly successful procedure for the relief of debilitating pain associated with degenerative joint disease. The 10- to 15-year survivorship of primary TKAnow routinely exceeds 90%. 1,2 However, despite advancements in surgical technique, implant design, and postoperative management, postoperative stiffness continues to be a relatively common complication. 3-5 Stiffness is defined as an inadequate range of motion (ROM) that results in functional limitations in activities of daily living. Although early studies reported stiffness in >50% of patients with TKA, 6 the true incidence appears to be 8% to 12%. 3,7,8 The incidence of complete fibrous ankylosis after TKA is about 0.1%. Biomechanical studies and gait analysis have shown that patients require 67 of knee flexion during the swing phase of gait, 83 to ascend stairs, 90 to 100 to descend stairs, 93 to rise from a standard chair, and up to 105 to rise from a low chair. 9,10 There are no universally accepted criteria for diagnosis of stiffness, nor does consensus exist on appropriate timing of intervention. Thorough understanding of the multiple etiologies and available management options can help prevent stiffness in most patients and improve outcomes. Etiology The etiology of stiffness after TKA is most commonly multifactorial. Predisposing factors can be classified as preoperative, intraoperative, and postoperative. Preoperative Risk Factors Factors that may affect ROM after TKA include limited preoperative ROM, indication for surgery, or history of prior surgery. 5,11-15 Preoperative ROM is an important predictor of ultimate ROM after TKA Ritter and Stringer 11 found that the amount of achieved postoperative flexion correlated with the amount of preoperative flexion. In their study, 8 patients with mean preoperative flexion 75 achieved mean flexion of 85.6 at 1 year after surgery, whereas 43 patients with mean preoperative flexion of 76 to 95 had mean postoperative flexion of An interesting trend observed in studies of patients with poor preoperative flexion (<90 ) is that they tend to gain flexion postoperatively; patients with a mean preoperative flexion >105 tend to experience a net loss in flexion, despite retaining greater mean ROM overall Dr. Bong is Orthopaedic Resident, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY. Dr. Di Cesare is Director, Musculoskeletal Research Center, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, and Associate Professor, Department of Orthopaedic Surgery and Cell Biology, New York University School of Medicine, New York. None of the following authors or the departments with which they are affiliated has received anything of value from or owns stock in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Bong and Dr. Di Cesare. Reprint requests: Dr. Di Cesare, NYU Hospital for Joint Diseases, Room 1500, 301 East 17th Street, New York, NY Copyright 2004 by the American Academy of Orthopaedic Surgeons. 164 Journal of the American Academy of Orthopaedic Surgeons

2 Matthew R. Bong, MD, and Paul E. Di Cesare, MD The association of postoperative ROM with indications for TKA, obesity, and previous knee surgery is less direct. Patients with inflammatory arthritis seem to have a greater gain in postoperative ROM than do those with osteoarthritis ,16 Obesity has been observed to negatively influence postoperative ROM, 14 possibly because of impingement of excessive posterior soft tissues. However, Daluga et al 7 found that obesity was not predictive of the development of stiffness. Although a history of previous surgical procedures has been shown to affect outcomes after TKA, such a history has not been universally accepted as a predictor of postoperative ROM and stiffness. Katz et al 15 found that the average arc of motion in 21 patients who underwent TKA for failed proximal tibial osteotomy was 8 less than that of 21 matched control patients who underwent primary TKA for osteoarthritis. However, the final mean arc of motion was 95 in the failed-osteotomy group, and no statistically significant difference existed between the two groups in the manipulation rate for management of postoperative stiffness. Harvey et al 12 showed that previous proximal tibial osteotomy had no effect on ultimate ROM. Follow-up studies of patients who underwent TKA after failed unicompartmental knee arthroplasty have demonstrated average postoperative ROM arcs of from 104 to Saleh et al 20 recently reported a series of 15 patients who underwent TKA after open reduction and internal fixation of tibial plateau fractures. The average active postoperative arc of motion was 105 ; however, the complication rate was high. Three patients underwent manipulation for stiffness, three developed deep infection, and two had patellar tendon rupture. Keloid or hypertrophic scar formation, which can lead to a noticeable cosmetic deformity, also has been implicated in the development of anatomic dysfunction. However, keloid or scar formation does not seem to affect ROM after TKA. Similarly, age, sex, multiple joint involvement, and bilateral TKA do not affect postoperative ROM. 7,16,21 Intraoperative Risk Factors Intraoperative technical factors may lead to postoperative limitations in flexion, extension, or both. Limitations in flexion or flexion contractures can result from improper flexion-extension gap balancing, malpositioning or oversizing of components, inadequate femoral or tibial resection, excessive joint line elevation, creation of an anterior tibial slope, or incompletely resected posterior osteophytes. A tight or overstuffed flexion gap can be created in several ways. In a revision setting, the femur can be excessively shortened; the extension gap looseness is then treated by inserting a thicker tibial component (Fig. 1). Alternatively, an oversized or correctly sized femoral implant can be shifted posteriorly. This also can occur during a primary TKA when anterior referencing instruments are used and a larger femoral component is chosen when the sizing gauge measurement is in between sizes. When posterior cruciate ligament (PCL)- retaining components are implanted, excessive tightening of the PCL also can cause limited motion. Finally, malrotation of the femoral component can create an asymmetric flexion gap, thereby limiting motion. Inadequate distal femoral resection with a taut posterior capsule can lead to a tight extension gap and create a flexion contracture. Tightness in both flexion and extension usually occurs because of technical errors on the tibial side. Resection of an inadequate amount of tibial bone or insertion of a polyethylene insert that is too thick can lead to flexion and extension gap tightness. Overstuffing of the patellofemoral joint also has been implicated in the development of excessive tightness of the extensor mechanism and stiffness after TKA. This occurs with inadequate resection of the patella or anterior placement of the femoral component. The amount of patella resected should be equal to the thickness of the patellar insert, with a 2- to 3-mm adjustment for cartilage loss. 22 Shoji et al 14 found that an increase of 20% in patellar thickness led to a significant decline in postoperative flexion. Daluga et al 7 observed that an increase of 12% in anteriorposterior knee diameter after surgery led to a marked increase in postoperative stiffness. Joint line elevation after TKA is another cause for development of postoperative stiffness, especially in PCLretaining designs. Elevation of the joint line creates a relative patella baja and abnormal patellofemoral joint forces. Figgie et al 23 observed notably less flexion in patients with at least 10 mm of joint elevation; Shoji et al 14 reported similar results when the joint line was elevated 16 mm. Posterior impingement can be observed in knees with an anterior tibial slope. Flexion becomes limited as the femur impinges on the posterior lip of the tibial component. Incompletely resected posterior osteophytes can impinge on the tibial component and limit flexion while tenting the posterior capsule during extension, leading to flexion contractures. Although not universally accepted as a means to improve postoperative flexion, closing the capsule and fascia while the knee is flexed may provide increased flexion by avoiding excessive tightening of the extensor mechanism. One prospective study of knee closure at 60 of flexion found no benefit over knees that were closed in extension. 24 However, in another series, closing the capsule and fascia with the knee flexed 90 to 110 provided 5 more flexion at 1 year than in knees that were closed in extension. 25 Use of a tourniquet intraoperatively has been shown to inhibit knee flexion in the first week, but no difference was observed at 6 weeks. 26 Although preoperative flexion has been Vol 12, No 3, May/June

3 Stiffness After Total Knee Arthroplasty Figure 1 Anteroposterior (A) and lateral (B) radiographs of a 60-year-old woman 1 year after revision TKA. A thick tibial polyethylene insert was used to accommodate a loose extension gap, leading to a tight flexion gap and stiffness. Anteroposterior (C) and lateral (D) radiographs after second revision arthroplasty with distal femoral augmentation, which led to balanced flexion and extension gaps with an improved ROM. strongly correlated with postoperative ROM, intraoperative flexion against gravity also may be a predictor of knee flexion after TKA. 27 Intraoperative flexion is tested after capsular closure by passively flexing the hip to 90 and allowing the weight of the leg to flex the knee. Postoperative Risk Factors Postoperative factors that can lead to inadequate knee ROM include poor patient motivation and compliance, deep infection, arthrofibrosis, patellar complications, complex regional pain syndrome (CRPS), and heterotopic ossification (HO). The importance of patient compliance and expectations in obtaining a satisfactory result cannot be overemphasized. Poorly motivated patients are less likely to mobilize and ambulate after surgery or comply with the postoperative ROM program. They may be helped by a support network developed through family education and physical therapy. Deep infection, which occurs postoperatively in 1% to 2% 28,29 of patients who have undergone TKA, can cause dramatic stiffness. Infection should be considered in any patient who develops stiffness after having achieved adequate ROM. Complications affecting the patella often cause pain, which may lead to stiffness as the patient volitionally limits ROM. Such complications include pain in the unresurfaced patella, fracture, maltracking, and loosening. Pathologic scar formation includes peripatellar fibrous bands, fibrosis of the PCL, and severe arthrofibrosis involving the entire joint. CRPS is an uncommon complication, with a 1% incidence after TKA. It occurs as a result of an exaggerated sympathetic response to surgical trauma, leading to prolonged pain, limited motion, vasomotor disturbances, and poor functional recovery. 30 The incidence of radiographically apparent HO after TKA may be as high as 10% to 26%; however, HO significant enough to inhibit knee ROM is far less common. 31,32 Management Patients with persistent stiffness in the first 3 months after TKA who do not have an infection and are well aligned with securely fixed components may benefit from aggressive physical therapy or a structured home therapy program. Shoji et al 14 observed that patients who underwent organized daily physical therapy for 1 month after TKA had better knee flexion at 2- to 9-year follow-up than did patients with only 10 to 14 days of organized physical therapy. Mauerhan et al 8 discovered an inverse relationship between length of stay after TKA and manipulation rate for inadequate 166 Journal of the American Academy of Orthopaedic Surgeons

4 Matthew R. Bong, MD, and Paul E. Di Cesare, MD ROM. This relationship may reflect the loss of additional days of aggressive inpatient physical therapy. A structured ROM program, either on an individual basis or with physical therapy, should be continued for as long as ROM continues to improve. Once a plateau is reached, further aggressive therapy may contribute only to patient discomfort. Patients with late-onset knee stiffness (ie, >3 months after TKA and after adequate ROM had been achieved initially) also are less likely to benefit from physical therapy. Every effort must be taken to determine the cause of the stiffness. Patients with HO after TKA may benefit from physical therapy and manipulation. 7 Although heterotopic bone has been associated with knee stiffness in some patients, the role and efficacy of excision of HO about the knee (unlike the hip) are unknown. Patients with limited knee motion secondary to CRPS may benefit from sympathetic blockade and physical therapy. Table 1 Results of Manipulation After TKA Study No. of Patients (Knees) Mean Immediate Gain in Range of Motion Manipulation Manipulation can be considered when knee ROM is inadequate despite an aggressive program to gain motion. Controversy continues regarding both the usefulness and timing of manipulation. Brassard and Scuderi 33 recommend manipulation if ROM is <75 by 6 to 12 weeks. Scranton 3 recommends manipulation if ROM is <90 by 6 weeks. Fox and Poss 5 and Shoji et al 14 recommend manipulation much earlier by 2 weeks and 10 days, respectively if flexion by then is <90. Manipulation appears to have notably better results when undertaken within the first 3 months after TKA. Several studies have evaluated the results of manipulation in patients with limited flexion after TKA (Table 1). However, these studies provide little insight into the use of manipulation for postoperative flexion contractures. Fox and Poss 5 achieved an immediate 37 gain in flexion after manipulation; however, 1 week after manipulation, the average retained flexion gain was only 17. After 1 year, the manipulated knees had ROM comparable to the nonmanipulated knees. Daluga et al 7 achieved a 35 increase in mean flexion with manipulation; however, the final mean flexion achieved (103 ) was less in the manipulated group than in the control group (109 ). In this same study, patients who underwent manipulation more than 3 months after TKA achieved a final mean flexion of 97, compared with 104 in patients with early manipulation. Esler et al 4 saw similar gains in flexion after manipulation. Their patients achieved a mean increase of 34 flexion at manipulation that held up at 33 after 1 year. If patients fail to progress to 90 of flexion in the first 6 weeks despite aggressive physical therapy, manipulation under regional anesthesia followed by a structured pain management program should be considered. Knee aspiration for bacterial culture can be conducted at the same time to rule out an infectious etiology for the stiffness. During manipulation, the knee is firmly and progressively flexed until the tearing of adhesions is no longer audible or palpable or until a firm is reached. Overly aggressive manipulation of the knee can result in complications such as supracondylar femur fracture (Fig. 2), patellar tendon avulsion, quadriceps tendon tears, hematoma formation, and wound dehiscence. 5,34 Mean Total Final Gain in Range of Motion (Mean Time to Follow-up) Mean Timing of Manipulation Daluga et al 7 60 (94) (24 mo) N/A Fox and Poss 5 76 (76) (1 wk) 2 wk Esler et al 4 42 (47) (12 mo) 11.3 wk Surgical Débridement Arthroscopic débridement of adhesions in combination with manipulation has been shown to substantially improve knee ROM in patients with postoperative arthrofibrosis resulting from surgical procedures other than TKA However, arthroscopic lysis of adhesions after TKA has not been as successful as lysis after procedures other than TKA (Table 2). Bocell et al 38 observed that only two of seven patients maintained pain-free improvements in ROM after arthroscopic débridement of arthrofibrosis and manipulation after TKA. Campbell 39 observed an increase in flexion of only 11 and an increase in extension of only 5.5 in eight patients 1 year after arthroscopy. Others have reported more marked improvements in ROM. After arthroscopic débridement and manipulation, Diduch et al 40 reported a 26 improvement in mean flexion in eight patients, and Scranton 3 observed a 31 gain in mean ROM; however, neither study examined the effect of arthroscopy on flexion contractures. Bae et al 41 reported a mean improvement of 42 in the total arc of motion at 1-year followup in 13 knees; the improvement in flexion contractures was less clear. Patients with flexion limitations who receive a PCL-retaining total knee component may benefit from arthroscopic release of the PCL. Williams et al 42 observed an increase in mean flexion of 30 and an improvement in mean knee Vol 12, No 3, May/June

5 Stiffness After Total Knee Arthroplasty Figure 2 Premanipulation (A) and postmanipulation (B) lateral radiographs of a 48-yearold man with a supracondylar distal femur fracture that occurred during manipulation and required surgical fixation. extension from 4 to 1.5 at 20-month follow-up in 10 knees after arthroscopic PCL release. When adhesions are more extensive, electrocautery, arthroscopic scissors, and large-radius shavers can be used to débride the suprapatellar pouch and the medial and lateral gutters. An alternative to arthroscopic lysis of adhesions is a modified open lysis of adhesions, which in one series of four knees resulted in a mean increase in ROM of In this technique, 1-cm lateral, medial, and superolateral portals are created. Scissors are passed through the lateral and superolateral portals with the blades open, to release the adhesions in the lateral gutter and the suprapatellar pouch. The scissors are then passed through the medial portal with the blades closed, to release the adhesions in the medial gutter. The PCL then can be released from its medial femoral condyle insertion through a 2- to 3-cm miniarthrotomy at the previous lateral portal. No standard management protocol is followed for treatment of patients after arthroscopic lysis of adhesions. Combination of an aggressive physical therapy with adequate analgesia through an epidural catheter may be helpful to maintain ROM in the immediate postoperative period. Evidence supporting the use of formal open arthrolysis after TKA is sparse; Table 2 Results of Surgical Management of Stiffness Study No. of Patients (Knees) Technique Time From Total Knee Arthroplasty to Secondary Surgery (mean in months) Total Gain in Range of Motion (mean in degrees) Time to Follow-up (mean in months) Williams et al 42 9 (10) Posterior cruciate ligament release Campbell 39 8 (8) Lysis Diduch et al 40 8 (8) Lysis Bae et al (13) Lysis Sprague et al 35 1 (1) Lysis Scranton 3 7 (7) Lysis N/A Scranton 3 4 (4) Modified open N/A Nicholls and Dorr (13) Revision N/A 33 N/A (range, 24-84) Ries and Badalamente 45 5 (6) Revision Babis et al 44 7 (7) Open lysis and tibial insert exchange * 50 *Does not include data from two patients who required rerevision 168 Journal of the American Academy of Orthopaedic Surgeons

6 Matthew R. Bong, MD, and Paul E. Di Cesare, MD this should be used only as a salvage procedure. Quadricepsplasty can accompany open lysis of adhesions to increase postoperative flexion. Revision Arthroplasty In patients with stiffness after TKA secondary to oversized, malpositioned, or loose components, revision arthroplasty is the preferred treatment. However, revision arthroplasty done to treat stiffness secondary to arthrofibrosis has generated mixed results (Table 2). Nicholls and Dorr 43 reported a mean increase in arc of motion of 42 in nine knees with malpositioned or loose components. Four patients with a mean preoperative flexion contracture of 33 were corrected to a mean of 8 after revision arthroplasty. But in three knees with arthrofibrosis that limited knee ROM, revision surgery provided no improvement in ROM or standard knee rating scores. Although Babis et al 44 reported poor results with open arthrolysis and a thinner tibial polyethylene insert, Ries and Badalamente 45 reported better results with revision arthroplasty for patients with ROM limited solely by arthrofibrosis after TKA. They observed a mean increase in arc of motion of 50 in six knees at a minimum 2-year follow-up. In general, the results of revision surgery for the specific indication of knee stiffness have been unpredictable and may be influenced by an individual patient s soft-tissue response to surgical trauma. Radiographic evidence of loose, oversized, or malpositioned components, with negative work-up for infection or complex regional sympathetic dystrophy Revision arthroplasty Acceptable Figure 3 Physical therapy Stiffness after TKA Physical examination, radiographs, and laboratory studies 3 months postoperative Unacceptable Physical examination, radiographs, and laboratory studies normal Acceptable Manipulation followed by physical therapy Unacceptable Treatment Algorithm The most difficult aspect of treating stiffness after TKA is determining when to intervene (Fig. 3). Patients with early-onset stiffness (eg, <90 of flexion or a significant flexion contracture 3 months after surgery) who had adequate preoperative and intraoperative ROM but are not progressing with physical therapy should be considered for manipulation. A patient who achieved an acceptable ROM but then deteriorated >3 months after surgery must be carefully reevaluated for the specific etiology (eg, infection, component breakage or loosening, patellar complications, CRPS, or HO) and treated accordingly. The work-up for patients with stiffness after TKA includes the physical examination, anteroposterior and lateral radiographs, and, in some cases, laboratory studies such as a complete blood count, erythrocyte sedimentation rate, and C-reactive protein level. Knee aspiration for cell count and bacterial culture should be obtained in any patient with suspected infection after physical examination or laboratory studies. Although the most rapid progression in postoperative ROM occurs during the first 3 months, ROM can continue to increase for up to 2 years. 16 Patients with an anticipated final flexion of >90 usually attain 90 of flexion within the first 2 to 6 weeks. Prevention Radiographic, physical examination, or laboratory evidence of infection or complex regional sympathetic dystrophy Treat underlying etiology >3 months postoperative Arthroscopic lysis of adhesions with manipulation, followed by physical therapy (Use modified open lysis if technically unable to do arthroscopy.) Acceptable Treatment algorithm for stiffness after total knee arthroplasty. Unacceptable Consider revision arthroplasty Proper patient and implant selection is critical to minimize chances of a poor outcome after TKA. Patients must clearly define their expectations yet also understand their own role in Vol 12, No 3, May/June

7 Stiffness After Total Knee Arthroplasty producing a successful result. Also, patients need a support network during follow-up and must contact the surgeon if problems arise. Careful preoperative planning can help ensure availability of appropriately sized components. Intraoperatively, proper flexion-extension balancing must be achieved. Closure of the capsule with the knee in flexion, rather than closure in extension, may provide additional ROM. After capsular closure, knee flexion against gravity is perhaps the best predictor of final ROM after TKA. Physical therapy or some other structured program consisting of 4 to 6 weeks of knee ROM and strengthening exercises after TKAmay be beneficial in preventing adhesions and contractures. Patients are more willing participants in their rehabilitation when adequate postoperative analgesia accompanies such an aggressive regimen. The utility of continuous passive motion (CPM) is a subject of debate. Although CPM has not demonstrated any long-term benefit in ROM after TKA, there is some evidence that immediate application of CPM may improve ROM during the first month Summary Postoperative stiffness after TKA can occur even when the surgeon adheres to meticulous surgical technique and properly sizes, aligns, and fixes the components. Unfortunately, no prospective randomized studies compare the various treatments or time to intervention for stiffness. Even a definition of stiffness eludes universal acceptance. Guidelines for the treatment of the patient with stiffness after TKA include proper pain management and close monitoring for proper motivation to participate in physical therapy. Guidelines for intervention apply to patients who once attained an acceptable intraoperative ROM. If patients fail to achieve 90 of flexion by 4 to 6 weeks, aggressive physical therapy should be initiated. If physical therapy fails within 3 months after surgery, closed manipulation should be considered. Arthroscopic or limited open lysis of adhesions can be conducted if the knee is stiff and more than 3 months has lapsed since surgery. There is little evidence to support the use of formal open lysis of adhesions. For patients with malpositioned or oversized components, revision arthroplasty is the preferred treatment. Patients who develop lateonset stiffness warrant a more intensive work-up to rule out other etiologies. References 1. Stern SH, Insall JN: Posterior stabilized prosthesis: Results after follow-up of nine to twelve years. J Bone Joint Surg Am 1992;74: Ritter MA, Herbst SA, Keating EM, Faris PM, Meding JB: Long-term survival analysis of a posterior cruciate-retaining total condylar total knee arthroplasty. Clin Orthop 1994;309: Scranton PE Jr: Management of knee pain and stiffness after total knee arthroplasty. 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8 Matthew R. Bong, MD, and Paul E. Di Cesare, MD 21. Tanzer M, Miller J: The natural history of flexion contracture in total knee arthroplasty: A prospective study. Clin Orthop 1989;248: Adam C, Eckstein F, Milz S, Schulte E, Becker C, Putz R: The distribution of cartilage thickness in the knee-joints of old-aged individuals measurement by A-mode ultrasound. Clin Biomech (Bristol, Avon) 1998;13: Figgie HE III, Goldberg VM, Heiple KG, Moller HS III, Gordon NH: The influence of tibial-patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg Am 1986;68: Masri BA, Laskin RS, Windsor RE, Haas SB: Knee closure in total knee replacement: A randomized prospective trial. Clin Orthop 1996;331: Emerson RH Jr, Ayers C, Higgins LL: Surgical closing in total knee arthroplasty: A series followup. Clin Orthop 1999;368: Wakankar HM, Nicholl JE, Koka R, D Arcy JC: The tourniquet in total knee arthroplasty: A prospective, randomised study. J Bone Joint Surg Br 1999;81: Lee DC, Kim DH, Scott RD, Suthers K: Intraoperative flexion against gravity as an indication of ultimate range of motion in individual cases after total knee arthroplasty. J Arthroplasty 1998; 13: Wilson MG, Kelley K, Thornhill TS: Infection as a complication of total kneereplacement arthroplasty: Risk factors and treatment in sixty-seven cases. J Bone Joint Surg Am 1990;72: Gaine WJ, Ramamohan NA, Hussein NA, Hullin MG, McCreath SW: Wound infection in hip and knee arthroplasty. J Bone Joint Surg Br 2000;82: Katz MM, Hungerford DS, Krackow KA, Lennox DW: Reflex sympathetic dystrophy as a cause of poor results after total knee arthroplasty. J Arthroplasty 1986;1: Furia JP, Pellegrini VD Jr: Heterotopic ossification following primary total knee arthroplasty. J Arthroplasty 1995; 10: Harwin SF, SteinAJ, Stern RE, Kulick RG: Heterotopic ossification following primary total knee arthroplasty. J Arthroplasty 1993;8: Brassard MF, Scuderi GR: Complications of total knee arthroplasty, in Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. New York, NY: Churchill Livingstone, 2001, pp Insall JN, Scott WN, Ranawat CS: The total condylar knee prosthesis: A report of two hundred and twenty cases. J Bone Joint Surg Am 1979;61: Sprague NF III, O Connor RL, Fox JM: Arthroscopic treatment of postoperative knee fibroarthrosis. Clin Orthop 1982;166: Del Pizzo W, Fox JM, Friedman MJ, Snyder SJ, Ferkel RD: Operative arthroscopy for the treatment of arthrofibrosis of the knee. Contemporary Orthopaedics 1985;10: Sprague NF III: Motion-limiting arthrofibrosis of the knee: The role of arthroscopic management. Clin Sports Med 1987;6: Bocell JR, Thorpe CD, Tullos HS: Arthroscopic treatment of symptomatic total knee arthroplasty. Clin Orthop 1991;271: Campbell ED Jr: Arthroscopy in total knee replacements. Arthroscopy 1987;3: Diduch DR, Scuderi GR, Scott WN, Insall JN, Kelly MA: The efficacy of arthroscopy following total knee replacement. Arthroscopy 1997;13: Bae DK, Lee HK, Cho JH: Arthroscopy of symptomatic total knee replacements. Arthroscopy 1995;11: Williams RJ III, Westrich GH, Siegel J, Windsor RE: Arthroscopic release of the posterior cruciate ligament for stiff total knee arthroplasty. Clin Orthop 1996; 331: Nicholls DW, Dorr LD: Revision surgery for stiff total knee arthroplasty. J Arthroplasty 1990;(5 suppl):s73-s Babis GC, Trousdale RT, Pagnano MW, Morrey BF: Poor outcomes of isolated tibial insert exchange and arthrolysis for the management of stiffness following total knee arthroplasty. J Bone Joint Surg Am 2001;83: Ries MD, Badalamente M: Arthrofibrosis after total knee arthroplasty. Clin Orthop 2000;380: Lachiewicz PF: The role of continuous passive motion after total knee arthroplasty. Clin Orthop 2000;380: Lau SK, Chiu KY: Use of continuous passive motion after total knee arthroplasty. J Arthroplasty 2001;16: Pope RO, Corcoran S, McCaul K, Howie DW: Continuous passive motion after primary total knee arthroplasty: Does it offer any benefits? J Bone Joint Surg Br 1997;79: Vol 12, No 3, May/June