Evaluation and Management of the Stiff TKA @ International Congress for Joint Reconstruction Authors: Adeel Husain, MD; Roman Stedman, BS; and Charles Nelson, MD, are from the Department of Orthopaedic Surgery, Adult Reconstruction Section, at the University of Pennsylvania, Philadelphia, Pennsylvania. Stiffness following total knee arthroplasty causes pain and diminished function. In this article, the authors review key principles in the work-up and treatment of stiffness after TKA, as well as provide tips and guidelines for dealing with this complication of knee replacement. Introduction Stiffness is an infrequent yet disabling complication following total knee arthroplasty (TKA). Patients who experience stiffness after TKA complain of pain and diminished function. In two large studies, the prevalence of stiffness after TKA ranged from 1%  to 5%  at approximately 2.5 years postoperatively. It is important to note that both studies used similar definitions for the term “stiffness.” Arthrofibrosis has been ranked as the fifth leading cause of TKA failure (7%) for several time-points over 15 years of follow-up.  Recently, systematic reviews of the literature have highlighted treatment options and hinted at treatment algorithms for stiffness after TKA. [4,5] However such algorithms have varied due to differing outcome measures, differing definitions of stiffness used as inclusion criteria, and scarcity of Level I and Level II evidence in the literature. This article reviews key principles in the workup and treatment of stiffness after TKA. It also provides common tips and guidelines for dealing with this complication of knee replacement. Definition A proposed definition of stiffness is a flexion contracture of ≥15° and/or <75° of flexion. A 15° knee flexion contracture requires 22% more extensor demand to stand on a flexed knee.  This increased demand makes it more difficult for patients to perform activities of daily living, such as walking, standing, and ascending stairs.  Approximately 70° of flexion is required for normal gait  and 80° to climb stairs foot over foot.  These studies, along with others, have set guidelines for the definition of stiffness used by many today. Table 1. Factors Associated with Stiffness Following TKA Preoperative Considerations Preoperative or patient-identified risk factors for postoperative stiffness include: [1,2,5,10-12] Preoperative stiffness Younger age Posttraumatic arthritis Multiple prior surgeries When preoperative range of motion (ROM) is decreased, the surgeon must pay special attention to managing patient expectations before surgery. Extrinsic conditions such as obesity with excessive soft tissue across the joint or ipsilateral hip osteoarthritis can lead to decreased ROM following a successful TKA. Shortened quadriceps or hamstrings may lead to extrinsic limitations to flexion and extension respectively that cannot be addressed by component revision, and only by muscle release or lengthening if appropriate. In cases of childhood inflammatory arthritis conditions, stiffness may be secondary to muscles that never grew long enough to allow full knee ROM. At least in the setting of hemophiliac arthropathy, there is evidence that knee ROM can increase late, beyond 18 months, with continued physical therapy and stretching of extrinsic muscles.  Patients with these risk factors must be made aware before surgery that they have an increased chance of limited motion postoperatively. Intraoperative Considerations Optimal stability and ROM is attained from proper bone removal, component position, and soft tissue balance during the TKA procedure. Proper bone removal from the distal femur, posterior femur, and proximal tibia ensures that the collateral ligaments are tensioned appropriately. If not enough bone is removed during surgery, overstuffing of the joint can lead to stiffness. In extreme cases, over-tensioning can limit the ability of the soft tissues to accommodate a prosthetic device. On the other hand, over-resection of bone loosens the collateral ligaments and can cause instability. Suboptimal component positioning (internal rotation of the tibial or femoral components) or sizing can cause ligament imbalance and postoperative stiffness or instability. [14,15] Improper rotation can cause asymmetric flexion: tightness in the direction of rotation and laxity in the opposite direction (Figure 1). These cases of stiffness can be improved after revision surgery. Figure 1. Differing femoral component positions can lead to stiffness and instability. A properly positioned femoral component (a, left) will have ligaments appropriately tense both medially and laterally. Suboptimal femoral component position in internal rotation (b, right) causes ligament imbalance. This presents as excess tightness medially and excess laxity laterally which can lead to both stiffness as well as instability. Whether ROM is affected by the choice of a cruciate-retaining versus a cruciate-sacrificing implant is subject to much debate. However, this choice has not been shown to be related to stiffness following TKA.  Meticulous surgical technique and attention to soft tissue is important in minimizing surgical factors that can cause a stiff TKA, as technical errors can limit flexion or extension (flexion contracture): Improper soft tissue balancing during the initial procedure can limit postoperative ROM. Failure to restore posterior femoral condylar offset and substantial elevation of the joint line can lead to limitations in flexion. Failure to remove posterior osteophytes or to release a tight posterior capsule can lead to limitations in both flexion and extension. Improper balancing of the flexion and extension gaps can limit both flexion and extension. Closing the arthrotomy in flexion may allow patients to regain motion faster and with less effort than those closed in extension.  Pathologically tight soft tissue or skin contractures from prior scars can be excised, and contracted quadriceps muscle should be released to allow improved motion.  Postoperative Considerations Postoperative factors that lead to stiffness include: Infection Improper pain management Development of pathological states that limit knee motion Patients who present with early postoperative stiffness should be evaluated for infection with appropriate laboratory tests and imaging, with further workup if necessary. Once infection is ruled out, poor pain management should be high on the differential diagnosis. Inadequate pain management after TKA ranks as a major source of stiffness. Pain prevents ROM, which leads to ineffective physical therapy (PT). Optimized pain management will allow patients to maximize their efforts during postoperative rehabilitation. Pathological states can limit knee motion. Complex regional pain syndrome (CRPS) may be suspected in patients who present with skin changes (color, hair pattern, temperature), decreased patellar mobility, hyperalgesia, and a lack of other objective findings explaining their limited ROM. In these cases, a diagnostic/therapeutic sympathetic block may aid in pain control. If stiffness continues with increased follow-up, idiopathic arthrofibrosis may be suspected. In this scenario, excessive scar formation during the healing process can be managed by manipulation under anesthesia (MUA). If, attempts at MUA are unsuccessful shortly after surgery, technical factors, such as suboptimal component sizing or placement, should be considered. Management Conservative Modalities Conservative modalities for stiffness in the early postoperative period include: PT Optimized multimodal pain control Dynamic or static progressive splinting, particularly for extension Continuous passive motion (CPM) machines have not been shown to improve long-term ROM or clinical outcomes.  However CPM plus PT may increase knee flexion more than PT alone 2 weeks after surgery.  Manipulation Under Anesthesia (MUA) If stiffness persists in the early postoperative period without infection or technical problems, MUA has been shown to reliably improve ROM, especially in flexion. MUA is most appropriate within 2 to 3 months of the index TKA.  Beyond 3 months, the risk of iatrogenic fracture increases. Ranawat et al demonstrated improved results with MUA combined with intraarticular injection of an anesthetic/analgesic cocktail for postsurgical pain control.  Pariente and Lombardi showed that use of a continuous epidural infusion after MUA resulted in improved ROM for persistently stiff patients, especially in those with a suspicion of CRPS.  Lysis of Adhesions and Posterior Cruciate Ligament Release If MUA has not been performed in the 3-month window after TKA, lysis of adhesions (LOA) may be appropriate, as long as infection and technical problems have been ruled out. This can be done either arthroscopically or open, and sometimes in combination with manipulation.  Arthroscopic LOA shows substantial improvements in ROM even when performed 1 year after the index procedure. When comparing MUA and arthroscopic LOA (with or without concurrent MUA), the final ROM is similar. Outcomes are not as successful when performing an open LOA, however.  LOA can be performed in cases of arthrofibrosis and limited ROM after the index TKA and in patients with CRPS unresponsive to conservative measures. LOA is most appropriate in patients who likely would have had good outcomes following MUA but are outside the safe window for MUA. This may be seen in patients with medical complications in an ICU setting where ROM and pain control were not prioritized early. In properly selected patients with properly positioned components, there may be a role for arthroscopic posterior cruciate ligament (PCL) release. Patients should have a PCL-retaining knee with a tight PCL and increased posterior rollback. Generally, this procedure should be performed within 15 to 18 months of the index TKA.  Revision TKA Revision TKA is the workhorse for a stiff TKA. Outcomes with complete revision are generally much better than with limited approaches. Although improvements in ROM are modest, appropriately selected patient tend to be more satisfied after revision TKA.  If the source of stiffness is identified, the most reliable treatment in late presentations is revision TKA. Indications include: Inadequate bone resection Malpositioned or oversized components Other technical factors that lead to overstuffing or tightened soft tissues During a revision procedure, it is important to optimize component size, position, alignment, and rotation. In addition, patella component revision may be indicated if patellar resurfacing has led to increased composite thickness of the patellar component and residual bone. As with primary TKA, pain control following a revision procedure is essential to allow optimal ROM and function. Technical Pearls during Surgery  Address extrinsic factors (such as tight quads or hamstrings) that can preclude optimal ROM Free and decompress the gutters More difficult exposures risk avulsion of the patellar tendon Have a low threshold for lateral retinacular release or quadriceps snip Restore the joint line to optimize rotation, position, alignment, and flexion/extension balance Release contracted quadriceps off the femur and reestablish tissue planes Avoid an overstuffed patellofemoral joint Assess ROM with the extensor mechanism/patella subluxed and then reduced Reminder: Postoperative ROM will not be greater than intraoperative gravity ROM with a reduced patella after closure of the retinaculum  Summary By 6 weeks postoperatively, aggressive PT should be started if the patient cannot flex to 90°. Within the first 3 months, optimization of pain control, appropriate PT, and MUA should be considered for ROM limitations. 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