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Knee stiffness and arthrofibrosis

69 citationsUpdated Sep 2026

Overview

Acquired idiopathic stiffness following primary total knee arthroplasty is defined as a range of motion of <90 degrees persisting for >12 weeks in the absence of complicating factors [1]. This relatively common complication arises from multifactorial etiologies involving preoperative, intraoperative, and postoperative factors [3]. Patients experiencing stiffness face significantly higher treatment costs for both operative and nonoperative interventions compared to those without stiffness [41]. While concern for stiffness alone should not serve as a categorical barrier to total knee arthroplasty or manipulation under anesthesia when clinically indicated, increasing obesity severity is not associated with higher rates of postoperative stiffness or inferior outcomes following manipulation under anesthesia [106].

Arthrofibrosis is a rare but potentially devastating complication after ACL reconstruction, with roughly 2% of patients requiring intervention [10]. Risk factors in multiligament knee injury patients include younger age, worse preoperative flexion, and delayed return to weightbearing as tolerated [15]. An immediate motion and early intervention program demonstrated a 0% incidence rate of permanent arthrofibrosis and a 0.7% reoperation rate for knee motion limitations after ACL reconstruction [9]. Predictors of poor outcome for surgical treatment include global arthrofibrosis and a greater than 6-month time interval from primary reconstruction and surgical release [6], whereas early surgical intervention within 1 year improves the outcome if arthrofibrosis is evident [11].

Management requires a staged assessment and treatment approach beginning with nonsurgical management and manipulation under anesthesia, followed by surgical intervention such as lysis of adhesions or revision arthroplasty if surgical error is identified [4]. Gravity-assisted manipulation is a useful and effective treatment method for stiffness after knee surgery [8]. For patients with tibial eminence fractures, manipulation of the knee should be performed only in conjunction with lysis of adhesions if stiffness occurs after surgical fixation [14]. Specific classification systems and detailed revision techniques are addressed in subsequent sections.

Anatomy & Pathophysiology

Definition and Etiology

Arthrofibrosis is defined as painful stiffness accompanied by scarring and soft tissue proliferation [23]. Characteristic sonographic findings include synovial membrane thickening and neovascularity [23]. The reported incidence of arthrofibrosis following total knee arthroplasty ranges between 1 and 15%, depending on diagnostic criteria [23]. In one report, 1.3% of posterior stabilized implants developed postoperative stiffness, with almost one half of these cases considered idiopathic [27]. A distinct acute postoperative cytokine response profile, characterized by significant differences in levels of 9 cytokines over the first 2 postoperative days, is associated with patients who develop stiffness 6 weeks after total knee arthroplasty [56]. Furthermore, a predominance of synovial sensory nerve fibers is observed in arthrofibrosis following total knee arthroplasty compared to osteoarthritis of the knee [92].

Pathophysiology and Mechanisms

Loss of knee motion following distal femur fractures results from damage to the quadriceps mechanism and joint surface as a consequence of initial trauma or surgical exposure [35]. Quadriceps scarring, with or without arthrofibrosis of the knee or patella–femoral joint, restricts knee movement [35]. Immobilization of the knee for periods of more than 3 weeks usually results in some degree of permanent stiffness [35]. In patients with severe arthrofibrosis, the patellar tendon continues to shorten over time, with mean length decreasing from 45 mm before surgery to 39 mm at most recent follow-up [25]. Concurrently, the Insall-Salvati index decreases from a mean of 0.98 preoperatively to 0.84 at most recent follow-up in these patients [25]. Manipulation under anesthesia could not restore normal patellar tilt of the arthrofibrotic knee [95]. Additionally, gender has a significant effect on knee kinematics in patients with arthrofibrosis after anterior cruciate ligament reconstruction during weight-bearing knee flexion [86].

Bony Anatomy

The bones of the knee are the distal femur, the proximal tibia, and the patella [44]. The medial femoral condyle is larger and projects farther posteriorly and distally than the lateral condyle [58]. Conversely, the lateral femoral condyle projects farther anteriorly and is wider in the medial-lateral direction than the medial femoral condyle [58]. The tibial articular surface slopes 7° to 10° in the sagittal plane [58]. The posterior slope of the tibia is a mean of 10.7° in the medial plateau and 7.2° in the lateral plateau [63]. The patella is the largest sesamoid bone in the body and averages 2.5 cm in thickness [58]. The patellar articular surface contains a vertical, central ridge that separates the broader lateral facet from the medial facet, and a smaller, more medial facet called the odd facet [58]. The intercondylar notch is of variable width and is the site of attachment of the cruciate ligaments [58].

Ligament Anatomy

The anterior cruciate ligament (ACL) travels from the medial border of the lateral femoral condyle to its insertion site anterolateral to the medial tibial spine [44]. The ACL prevents anterior translation and rotation of the tibia on the femur [44]. The posterior cruciate ligament (PCL) prevents posterior subluxation of the tibia on the femur [44]. The medial collateral ligament has superficial and deep portions which stabilize the knee to valgus stresses [44]. The lateral collateral ligament runs from the lateral femoral condyle to the head of the fibula and is the main stabilizer against varus stress [44]. The ACL is composed of 90% type I collagen and 10% type III collagen [58]. The mean length of the ACL is 33 mm and the mean midsubstance width is 11 mm [58]. The femoral attachment of the ACL is a semicircular area on the posteromedial aspect of the lateral femoral condyle [58]. The tibial attachment of the ACL is a broad, irregular, oval-shaped area slightly medial and anterior to the midline and between the medial and lateral tibial spinous processes [58]. The PCL is the largest of the intra-articular ligaments, with an average length of 38 mm and a mean diameter at the midpoint of 13 mm [71]. The PCL has two distinct bundles defined by their insertion on the femur: an anterolateral (AL) bundle and a posteromedial (PM) bundle [71]. The AL bundle of the PCL is larger and comprises 85% of the PCL's cross-sectional area [71]. The PCL inserts onto a midline depression on the tibia, 10 to 15 mm below the level of the medial and lateral tibial plateaus [71].

Menisci and Joint Capsule

The menisci are C-shaped fibrocartilaginous disks in the knee that provide shock absorption, allow for increased congruency between joint surfaces, enhance joint stability, and aid in distribution of synovial fluid [44]. The medial meniscus is firmly attached to the joint capsule along its entire peripheral edge [44]. The lateral meniscus is attached to the anterior and posterior capsule, but there is a region posterolaterally where it is not firmly attached [44]. The medial meniscus has less mobility than the lateral meniscus and is more susceptible to tearing when trapped between the femoral condyle and tibial plateau [44]. The lateral meniscus is larger than the medial meniscus and carries a greater share of the lateral compartment pressure [44]. The menisci consist of type I collagen fibers arranged obliquely, radially, and vertically [63]. Vascular supply to the menisci is derived from the geniculate arteries, which penetrate into 20% to 30% of the peripheral medial meniscus and 10% to 25% of the peripheral lateral meniscus [63]. The medial meniscus is crescent-shaped and attaches more anterior and posterior [63]. The lateral meniscus is circular in shape and covers a larger proportion of the tibial plateau [63].

Synovial Plicae

The knee joint forms from three synovial compartments that normally fuse into a single synovial cavity [70]. Important synovial plicae of the knee represent unresolved remnants of these partitions and are classified as suprapatellar, infrapatellar, medial patellar, and lateral patellar plicae [70]. The infrapatellar plica, or ligamentum mucosum, can make it difficult to pass the arthroscope from one compartment to the other [70]. The medial patellar plica is the most common of these plicae to be of clinical significance, with an incidence reported to range from 10% to more than 50% in normal knees [70]. A pathologic medial patellar plica has a thickened, rounded, fibrotic, and white inner border [70]. As the knee moves from extension to 90 degrees of flexion, a pathologic medial patellar plica makes firm contact with the underlying femoral condyle at 30 to 40 degrees of flexion [70].

Kinematics

The greatest range of motion in the knee occurs in the sagittal plane, approximately 160° [75]. Knee rotation ranges from 45° in external rotation to 30° in internal rotation [75]. The "screw-home" mechanism involves the tibia externally rotating 5 degrees in the final 15 degrees of extension [59]. In full extension, the knee slightly hyperextends with slight tibial external rotation while collateral and cruciate ligaments are tightened to lock the knee in extension [76]. The popliteus muscle initiates flexion by pulling the lateral femoral condyle backward while the medial femoral condyle slides forward, resulting in tibial internal rotation [76]. The normal instant center of the knee joint follows a semicircular path related to the tibiofemoral surface and ligaments crossing the joint [75]. Rupture of the cruciate ligaments or disruption of the tibiofemoral surface causes a major change in the path of the instant center, leading to articular dysfunction [75].

Classification

MRI Synovial Classification: The extent of joint flexion and extension differs by MRI synovial classifications and the severity of compartment arthrofibrosis in knees with failed total knee arthroplasties [36].

ACL Reconstruction Classification: A practical classification system provides guidelines for the successful treatment of most cases of arthrofibrosis of the knee after anterior cruciate ligament reconstruction [16].

Other Considerations: Standardised, accepted criteria for the diagnosis, classification, and grading of the severity of post-operative fibrosis of the knee are needed to facilitate patient identification for clinical trials and the development of clinical guidelines [26].

Clinical Presentation

The overall incidence of arthrofibrosis is difficult to determine owing to controversy regarding the range of motion at which the knee is considered stiff and whether flexion contracture represents a significant limitation independent of the arc of motion [27]. In pediatric and adolescent populations, the pooled prevalence of arthrofibrosis following ACL reconstruction is approximately 3.7% [48]. Among patients undergoing isolated arthroscopic ACL reconstruction who initiate supervised rehabilitation within 30 days after surgery, approximately 1 in 10 receive a diagnosis of arthrofibrosis within 12 months [52].

A detailed history for knee pain diagnosis includes onset, quality, duration, tempo, and location of symptoms, modifying factors, ability to bear weight, and history of trauma [91]. History of symptoms occurring in knee flexion and careful physical examination of patella mobility are key diagnostic factors for distinguishing a displacing lateral meniscus from patella dislocation [28].

Inspection of the knee can reveal skin abnormalities, evidence of trauma, malalignment, and swelling [91]. Palpation of the peripatellar tissue can reveal the presence of effusion and/or synovitis [91]. Determination of overall knee alignment (varus, valgus, or neutral) is important as an adjunct to the diagnostic process, as malalignment can be associated with and may point to the diagnosis of specific conditions [91]. Knee alignment should be assessed in both supine and standing positions, as bearing weight may change the knee’s alignment dynamically [91].

Range of motion testing is divided into active and passive components [91]. Flexion contractures and hyperextension should be noted during range of motion testing [91]. Blocks to motion can be pain-related or mechanical [91]. When active and passive ranges of motion differ, the diagnostician must differentiate between pain-related, mechanical, or neuromuscular causes [91]. Hip range of motion should be examined and may reveal resultant knee pain, indicating the possibility of referred pain from intra-articular hip pathology [91].

A detailed physical examination of the knee includes inspection, palpation, gait assessment, range of motion testing, stability testing, neurovascular assessment, a hip examination, and special tests aimed at the diagnosis of particular pathologies [91]. The extent of joint flexion and extension differ by MRI synovial classifications and severity of compartment arthrofibrosis [36].

Investigations

Clinical Assessment

History of symptoms occurring in knee flexion and careful physical examination of patella mobility are key diagnostic factors for distinguishing arthrofibrosis from other pathologies such as patellar dislocation [28]. The physical examination for knee injury includes observation of gait, comparison with the uninjured knee, assessment of swelling or effusion, and careful testing of active and passive range of motion [44]. A practical classification system provides guidelines for the successful treatment of most cases of arthrofibrosis of the knee [16]. The development of standardised, accepted criteria for the diagnosis, classification and grading of the severity of post-operative fibrosis of the knee will facilitate the identification of patients for inclusion in clinical trials and the development of clinical guidelines [26].

Imaging

Plain radiography: Plain radiographs are appropriate initial imaging studies for most knee conditions because they allow the assessment of traumatic injury, arthritis, patellofemoral alignment, osteochondral injury, bone neoplasm, and surgical implants [46]. Radiographic studies help confirm the clinical diagnosis of a joint disorder determined using the patient’s history and physical examination [46].

MRI: Advanced radiographic imaging studies may help assess overall limb alignment and further delineate intra-articular and extra-articular soft tissues, including cartilage, menisci, ligaments, tendons, muscles, and nerve and vascular structures [46]. MRI may be used to assess the continuity of the quadriceps or patellar tendon [46]. MRI may be used to assess the margin of resection for a neoplasm, identify vascular malformation, or define the location of nerves or vessels relative to popliteal cysts [46]. MRI synovial classifications correlate with the severity of compartment arthrofibrosis in knees with failed total knee arthroplasties [36]. Imaging of the knee is important for evaluating patients with knee pain, as the patellofemoral joint is a complex articulation dependent on both dynamic and static restraints for its function and stability [47].

Bone scan: Nuclear medicine studies provide a nonspecific study that does not define the etiology of an abnormality but rather the presence of an abnormality that may correlate with a clinical concern [46]. Technetium-99 (Tc-99) is a radionuclide that may help identify infection, neoplasia, occult fracture, bone healing, active phases of heterotopic ossification, implant loosening, or failure of osseointegration [46]. Gallium-67 (Ga-67) is a radionuclide that may help differentiate between aseptic and septic prosthetic loosening [46].

Treatment

Non-Operative

Stiffness following total knee arthroplasty (TKA) mandates a staged assessment and treatment approach that begins with nonsurgical management [4]. Early rehabilitation incorporating passive-assisted and active-assisted range of motion is critical to prevent limited motion after TKA [50]. Static progressive stretch improves range of motion in arthrofibrosis following TKA [23], while the gravity-assisted manipulation technique serves as a useful and effective treatment method for stiffness after knee surgery [8]. In the context of anterior cruciate ligament (ACL) reconstruction, an immediate motion and early intervention program demonstrated a 0% incidence rate of permanent arthrofibrosis and a 0.7% reoperation rate for knee motion limitations [9]. For distal femur fractures, early stable internal fixation with meticulous soft tissue handling and immediate immobilization maximizes the chance for an optimal outcome [35]. Most patients with distal femur fractures should achieve 90 degrees of knee flexion 4 weeks postoperatively [35]. Patients who fail to regain knee motion during the first month are best treated with aggressive range-of-motion exercises under the direction of a physician and physical therapist [35]. Immobilization of the knee for periods exceeding 3 weeks after a distal femur fracture usually results in some degree of permanent stiffness [35]. Infection must be ruled out first for all patients presenting with a stiff, painful TKA [50]. Sulfasalazine resolves joint stiffness in a rabbit model of arthrofibrosis, providing proof-of-concept that established joint stiffness can be resolved non-surgically [22].

Operative

Indications: Arthrofibrosis remains a rare but potentially devastating complication after ACL reconstruction, with roughly 2% of patients requiring intervention [10]. If arthrofibrosis is evident after ACL reconstruction, early surgical intervention (<1 year) improves the outcome [11]. Predictors of poor outcome after surgical treatment of arthrofibrosis following ligament reconstruction include global arthrofibrosis and a time interval greater than 6 months from primary reconstruction and surgical release [6]. In Schenck KD 3 and 4 multiligament knee injury patients, younger age, worse preoperative flexion, and longer time to return to weightbearing as tolerated are risk factors for arthrofibrosis [15]. Failure to regain at least 90 degrees of knee flexion between 8 and 10 weeks postoperatively after a distal femur fracture is worrisome and usually warrants additional treatment in physiologically young patients [35]. In a study of 205 pediatric patients treated surgically for a displaced tibial spine fracture, arthrofibrosis developed in 20 patients (10%) [49]. In a separate study of 40 patients treated surgically for a displaced tibial spine fracture, arthrofibrosis developed in 7 of the 40 patients (17.5%), necessitating a second surgery [49]. Patients who began range of motion therapy within 4 weeks of surgery for tibial spine fracture had substantially faster return to full activity and were less likely to experience the development of arthrofibrosis than those for whom rehabilitation was initiated after 4 weeks [49].

Surgical Approach / Technique: Manipulation under anesthesia (MUA) is a component of the staged treatment approach for stiffness after TKA, following nonsurgical management [4]. MUA is more reliable for loss of flexion than for loss of extension after TKA [50]. Early (≤3 months) MUA is safe and effective in treating knee arthrofibrosis in adolescent patients [29]. Equivalent range-of-motion outcomes were observed between arthroscopic lysis of adhesions, early MUA, and delayed MUA for the treatment of arthrofibrosis after TKA [96]. In patients with distal femur fractures, forceful manipulation should be avoided, and immediate mobilization of the knee is essential to maintain knee motion [35]. In the skeletally immature knee, isolated MUA for postoperative arthrofibrosis should be undertaken with extreme caution because of the documented risk of physeal injury [49]. Of eight patients treated with MUA alone for arthrofibrosis after tibial spine fracture, three sustained an intraoperative distal femoral physeal fracture [49]. Arthroscopic lysis of adhesions is a surgical intervention option for stiffness after TKA if nonsurgical management and MUA fail [4]. Arthroscopic arthrolysis compares well with other methods of treatment for stiffness with regard to improvements in range of motion and functional knee scores [12]. Arthrofibrosis of the knee can be successfully treated with arthroscopic arthrolysis [31]. Recent advances in arthroscopic technique have led to improved outcomes in patients with intra-articular fibrosis of the knee [43]. Arthroscopic scar resection for arthrofibrosis post-ACL reconstruction resulted in most patients improving their category and IKDC scores, with those having more severe arthrofibrosis preoperatively resulting in better gains [19]. The arthroscopic procedure successfully restores knee extension, flexion, and patellar mobility while minimizing additional trauma and preventing damage to peripheral structures without causing instability to the knee joint [37]. Surgical management of recalcitrant arthrofibrosis in the knee can restore full range of motion if a thorough lysis of adhesions is performed [30]. Arthroscopic lysis of adhesions combined with gentle manipulation of the knee is an approach to regain functional knee motion in patients with distal femur fractures who fail to regain at least 90 degrees of flexion between 8 and 10 weeks postoperatively [35]. MUA with lysis of adhesions is an effective procedure likely to result in range of motion and patient outcome scores similar to those of a nonarthrofibrotic knee after sulcus-deepening trochleoplasty [102]. Within orthopaedic sports medicine literature, there is variability in the reported treatment options for arthrofibrosis of the knee [34].

Implant Selection: Patients with severe arthrofibrosis can expect greater absolute range of motion gains and similar functional outcomes compared to nonsevere patients when treated with rotating hinge revision total knee arthroplasty [20]. In a series of 34 patients revised with a rotating-hinge prosthesis for arthrofibrosis, the mean arc of motion increased 20 degrees (from 74 to 94 degrees) compared to a 12-degree increase (from 87 to 99 degrees) in the non-rotating-hinge group [51]. Survivorship free of any revision at 10 years was 54% in the rotating-hinge group and 90% in the non-rotating-hinge group for arthrofibrosis revision total knee arthroplasty [51]. Forty percent of the revisions in the rotating-hinge group for arthrofibrosis were related to insert and bushing exchanges [51].

Revision: While revision for arthrofibrosis after TKA can be associated with significant improvements in range of motion and Knee Society scores, caution is advised given high rates of revisions, reoperations, and complications [18]. Modest gains in range of motion can be obtained with revision total knee arthroplasty along with wide resection of periarticular arthrofibrotic scarring and downsizing of the femoral implant, although pain may still persist [50]. Arthroscopic resection of arthrofibrotic scarring and open débridement with tibial insert exchange has been associated with variable results for stiffness after total knee arthroplasty [50].

Other Considerations: A new technique addressing major intra-articular and extra-articular elements limiting knee flexion offers low morbidity and ease of application as an alternative mini-invasive approach for severe arthrofibrosis [21]. Open debridement and soft tissue release is a salvage procedure for the severely arthrofibrotic knee that is refractory to arthroscopic treatment [25]. In a study of eight patients treated with open debridement and soft tissue release for severely arthrofibrotic knees, the mean patellar tendon length decreased from 45 mm before surgery to 39 mm at the most recent follow-up [25]. The calculated Insall-Salvati index decreased from a mean of 0.98 preoperatively to 0.84 at most recent follow-up in patients treated with open debridement and soft tissue release for severely arthrofibrotic knees [25]. Knee joint arthrosis was common on follow-up radiographs in five of the eight patients treated with open debridement and soft tissue release for severely arthrofibrotic knees [25]. Patients with significant loss of motion after a distal femur fracture may be candidates for quadricepsplasty as a late reconstructive procedure [35]. A more well-defined concept of arthrofibrosis and large prospective studies are needed to clarify management [24].

Complications

Stiffness / Arthrofibrosis: Arthrofibrosis is a common complication after total knee arthroplasty, with reported incidence ranging between 1 and 15% depending on diagnostic criteria [23]. It is an uncommon yet significant complication following ACL reconstruction in children and adolescents, with a pooled prevalence of approximately 3.7% [48]. In a retrospective chart review of 40 patients treated surgically for a displaced tibial spine fracture, arthrofibrosis developed in 7 of the 40 patients (17.5%) [49]. A common complication following distal femur fractures is loss of knee motion resulting from damage to the quadriceps mechanism and joint surface [35].

Risk Factors and Predictors: Global arthrofibrosis and a greater than 6-month time interval from primary reconstruction and surgical release are predictors of poor outcome in arthrofibrosis following ligament reconstruction [6]. Undergoing early ACL reconstruction within 6 weeks of ACL rupture does not increase the risk of arthrofibrosis [55]. There were no significant differences in postoperative stiffness, Tegner scores, or reoperation for stiffness between ACLR performed 10 days and ACLR performed at the 3-week point or after [42]. Arthrofibrosis developed markedly later in patients who were aspirated preoperatively for ACL reconstruction, possibly as a result of decreased intra-articular inflammation [32]. Patients who had begun ROM therapy within 4 weeks of surgery for tibial spine fractures had substantially faster return to full activity and were less likely to experience the development of arthrofibrosis than patients for whom ROM rehabilitation was initiated after 4 weeks [49].

Clinical Presentation and Pathology: Quadriceps scarring with or without arthrofibrosis of the knee or patella–femoral joint is thought to restrict knee movement following distal femur fractures [35]. Immobilization of the knee for periods of more than 3 weeks usually results in some degree of permanent stiffness following distal femur fractures [35]. In patients with severely arthrofibrotic knees treated with open debridement, the patellar tendon continued to shorten with time, decreasing from a mean length of 45 mm before surgery to 39 mm at the most recent follow-up [25]. The calculated Insall-Salvati index decreased from a mean of 0.98 preoperatively to 0.84 at most recent follow-up in patients with severely arthrofibrotic knees [25]. Knee joint arthrosis was common on follow-up radiographs in five of the eight patients with severely arthrofibrotic knees treated with open debridement [25]. The patellofemoral joint was the most commonly involved compartment in patients with severely arthrofibrotic knees [25].

Treatment Outcomes and Complications: Revision surgery for stiffness after total knee arthroplasty resulted in improved Knee Society scores and an increased arc of motion in 93% of knees, though the benefits are modest [5]. Revision TKA using rotating-hinge implants for arthrofibrosis provides substantial and clinically meaningful improvements in knee ROM [7]. Patients with severe arthrofibrosis can expect greater absolute ROM gains and similar functional outcomes compared to nonsevere patients when treated with rotating hinge revision total knee arthroplasty [20]. In a series of 34 patients revised with a rotating-hinge prosthesis for arthrofibrosis, the mean arc of motion increased 20 degrees (74°–94°) compared to a 12-degree increase (87°–99°) in the non-rotating-hinge group [51]. Survivorship free of any revision at 10 years was 54% in the rotating-hinge group and 90% in the non-rotating-hinge group for arthrofibrosis revision [51]. While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications [18]. The present literature is inadequate to predict which patients will achieve adequate outcomes from revision TKA based on the specific etiology of their stiffness [17]. Lysis of adhesion for arthrofibrosis after total knee arthroplasty is associated with increased risk of subsequent revision total knee arthroplasty [93]. In a study of 14 patients undergoing low-dose irradiation and constrained revision for severe, idiopathic arthrofibrosis following TKA, there were no significant complications at a mean follow-up of 34 months [27]. Thirteen of fourteen patients undergoing low-dose irradiation and constrained revision for severe, idiopathic arthrofibrosis following TKA had a 57° mean gain in range of motion [27]. Flexion contractures decreased by a mean of 28° in patients undergoing low-dose irradiation and constrained revision for severe, idiopathic arthrofibrosis following TKA [27]. Long-term motion improvement can be achieved by arthroscopic arthrolysis for arthrofibrosis after anterior cruciate ligament reconstruction [33]. Early surgical intervention (<1 year) improves the outcome if arthrofibrosis is evident [11]. The 0% incidence rate of permanent arthrofibrosis and 0.7% reoperation rate for knee motion limitations demonstrated the effectiveness of the immediate motion and early intervention program after ACL reconstruction [9]. In a study of pediatric tibial spine fractures, three of eight patients treated with manipulation under anesthesia alone sustained an intraoperative distal femoral physeal fracture [49]. Isolated manipulation under anesthesia for postoperative arthrofibrosis in the skeletally immature knee should be undertaken with extreme caution because of the documented risk of physeal injury [49]. Patients who have stiffness after primary TKA face significantly higher treatment costs for both operative and nonoperative treatments than patients who do not have stiffness [41]. The authors demonstrate gravity-assisted manipulation to be a useful and effective treatment method for stiffness after knee surgery [8].

Recovery

Definition and Etiology: Joint stiffness remains the single most common complication following surgical intervention for ACL reconstruction [53]. Approximately 1 in 10 patients undergoing isolated arthroscopic ACLR and initiating supervised rehabilitation within 30 days after surgery received a diagnosis of arthrofibrosis within 12 months [52]. In the context of total knee arthroplasty, a distinct acute postoperative cytokine response profile, characterized by significant differences in levels of 9 cytokines over the first 2 postoperative days, is present in patients who develop stiffness 6 weeks after TKA [56].

Risk Factors and Prevention: Global arthrofibrosis and a time interval of greater than 6 months from primary reconstruction to surgical release are predictors of poor outcome [6]. Preoperative aspiration of the knee is associated with a markedly later onset of arthrofibrosis, possibly due to decreased intra-articular inflammation [32]. Delaying the timing of ACL reconstruction is associated with a lower risk of arthrofibrosis requiring intervention, particularly in patients aged 30 years or younger [39]. However, acute ACLR within 8 days of injury does not appear to adversely affect ROM or result in increased stiffness in the knee joint when compared to delayed surgery [40, 54]. There were no significant differences between ACLR performed 10 days and ACLR performed at the 3-week point or after in terms of postoperative stiffness, Tegner scores, or reoperation for stiffness [42]. Earlier initiation of supervised physical rehabilitation is not associated with decreased arthrofibrosis after isolated arthroscopic anterior cruciate ligament reconstruction [52]. An immediate motion and early intervention program demonstrated a 0% incidence rate of permanent arthrofibrosis and a 0.7% reoperation rate for knee motion limitations [9].

Non-Operative Management: Stiffness after total knee arthroplasty requires a staged assessment and treatment approach beginning with nonsurgical management and manipulation under anesthesia [4].

Operative Management: Stiffness after total knee arthroplasty is treated with surgical intervention such as lysis of adhesions or revision arthroplasty if surgical error is identified [4]. Revision surgery for stiffness resulted in improved Knee Society scores and an increased arc of motion in 93% of knees, though the benefits are modest [5]. Arthroscopic arthrolysis provides moderate improvements in range of motion and functional knee scores, comparing well with other methods of treatment for stiffness [12]. Long-term motion improvement can be achieved by arthrolysis for arthrofibrosis after ACL reconstruction [33]. If arthrofibrosis is evident, early surgical intervention (<1 year) improves the outcome [11]. Patients with severe arthrofibrosis can expect greater absolute ROM gains and similar functional outcomes compared to nonsevere patients when undergoing rotating hinge revision total knee arthroplasty [20]. Revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, but caution is advised given high rates of revisions, reoperations, and complications [18]. Preoperative low-dose irradiation and Constrained Condylar or Rotating-hinge revision for severe, idiopathic arthrofibrosis following TKA resulted in a mean gain in range of motion of 57° and a decrease in flexion contractures by a mean of 28° with no significant complications at a mean follow-up of 34 months [27].

Key Evidence

  • [L1] Contemporary literature supports the definition of acquired idiopathic stiffness as a range of motion of <90 degrees persisting for >12 weeks after primary total knee arthroplasty in the absence of complicating factors. [1] (10.2106/jbjs.18.01217)
  • [L3] Incremental increases in patellar thickness led to incremental decreases in passive intraoperative knee flexion in patients with preexisting arthrofibrosis, with effects similar to knees without preoperative stiffness. [2] (10.1016/j.arth.2015.11.032)
  • [L5] Postoperative stiffness after total knee arthroplasty is a relatively common complication with multifactorial etiologies including preoperative, intraoperative, and postoperative factors. [3] (10.5435/00124635-200405000-00004)
  • [Paper] Stiffness after total knee arthroplasty is a challenging condition requiring a staged assessment and treatment approach, beginning with nonsurgical management and manipulation under anesthesia, followed by surgical intervention such as lysis of adhesions or revision arthroplasty if surgical error is identified. [4] (10.1055/s-0034-1396079)
  • [L3] Revision surgery was a satisfactory treatment option for stiffness, as Knee Society scores improved and 93% of knees had an increased arc of motion, though the results suggest the benefits are modest. [5] (10.2106/jbjs.e-00345)
  • [L4] Predictors of poor outcome were global arthrofibrosis and greater than 6-month time interval from primary reconstruction and surgical release. [6] (10.1007/s00167-011-1472-6)
  • [L1] Revision TKA using rotating-hinge implants for arthrofibrosis provides substantial and clinically meaningful improvements in knee ROM. [7] (10.1016/j.arth.2026.06.041)
  • [L5] The authors demonstrate GAM to be a useful and effective treatment method for stiffness after knee surgery. [8] (10.1016/j.eats.2023.07.046)
  • [L3] The 0% incidence rate of permanent arthrofibrosis and 0.7% reoperation rate for knee motion limitations demonstrated the effectiveness of the immediate motion and early intervention program. [9] (10.1007/s001670000126)
  • [L3] Arthrofibrosis remains a rare but potentially devastating complication after ACL reconstruction, with roughly 2% of patients requiring intervention. [10] (10.1007/s00167-015-3799-x)
  • [L3] If arthrofibrosis is evident, early surgical intervention (<1 year) improves the outcome. [11] (10.1007/s00402-004-0718-x)
  • [L4] Arthroscopic arthrolysis compares well with other methods of treatment for stiffness with regard to improvements in range of motion and functional knee scores. [12] (10.1007/s00167-009-0878-x)
  • [Paper] Arthroscopic lysis of adhesions with manipulation under anesthesia is a reliable surgical technique that can improve range of motion in patients with knee stiffness due to post-traumatic arthrofibrosis. [13] (10.1016/j.eats.2017.03.001)
  • [L4] Should stiffness occur, manipulation of the knee should be performed only in conjunction with lysis of adhesions. [14] (10.1177/0363546509348001)
  • [L3] Younger patients, those with worse preoperative flexion, and those who take longer to return to weightbearing as tolerated are at risk of arthrofibrosis. [15] (10.1177/23259671251383147)
  • [L4] The practical classification system provides guidelines for the successful treatment of most cases of arthrofibrosis of the knee. [16] (10.1177/036354659602400625)
  • [L4] The present literature is inadequate to predict which patients will achieve adequate outcomes from revision TKA based on the specific etiology of their stiffness. [17] (10.1016/j.arth.2018.04.036)
  • [L4] While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications. [18] (10.1016/j.arth.2018.03.037)
  • [L4] Most patients were able to improve their category and IKDC scores after surgery, with those having more severe arthrofibrosis preoperatively resulting in better gains. [19] (10.1177/2325967124s00301)
  • [L3] Patients with severe arthrofibrosis can expect greater absolute ROM gains and similar functional outcomes compared to nonsevere patients. [20] (10.1016/j.arth.2024.06.056)
  • [L4] The new technique addresses major intra-articular and extra-articular elements limiting knee flexion, offering low morbidity and ease of application as an alternative mini-invasive approach for severe arthrofibrosis. [21] (10.2106/jbjs.f.00963)
  • [L5] The results provide proof-of-concept that established joint stiffness can be resolved non-surgically. [22] (10.1002/jor.24499)
  • [L4] [23] (10.1007/s00167-009-0947-1)
  • [L4] A more well-defined concept of arthrofibrosis and large prospective studies are needed to clarify management. [24] (10.1007/s00167-017-4482-1)
  • [L4] [25] (10.1177/03635465990270050201)
  • [L4] [27] (10.1016/j.arth.2012.11.009)
  • [L4] History of symptoms occurring in knee flexion and careful physical examination of patella mobility are key diagnostic factors. [28] (10.1007/s00167-013-2729-z)
  • [L3] The findings of this study suggest that early (≤3 months) MUA is safe and effective in treating knee arthrofibrosis in adolescent patients. [29] (10.1177/23259671241299838)
  • [L5] Surgical management of recalcitrant arthrofibrosis in the knee has proven to be challenging but can restore full ROM if a thorough LOA is performed. [30] (10.1016/j.eats.2025.103646)
  • [L3] Arthrofibrosis of the knee can be successfully treated with arthroscopic arthrolysis. [31] (10.1177/2325967120s00307)
  • [L3] Arthrofibrosis developed markedly later in patients who were aspirated preoperatively, possibly as a result of decreased intra-articular inflammation. [32] (10.5435/jaaos-d-24-00468)
  • [L4] Long-term motion improvement can be achieved by arthrolysis. [33] (10.1016/j.arthro.2016.07.029)
  • [L4] Within orthopaedic sports medicine literature, there is variability in the reported treatment options for arthrofibrosis of the knee. [34] (10.1016/j.asmr.2024.100896)
  • [L3] Furthermore, the extent of joint flexion and extension differ by MRI synovial classifications and severity of compartment arthrofibrosis. [36] (10.1016/j.arth.2025.04.013)
  • [L5] The procedure successfully restores knee extension, flexion, and patellar mobility while minimizing additional trauma and preventing damage to peripheral structures without causing instability to the knee joint. [37] (10.1016/j.eats.2025.103446)
  • [L3] Delaying the timing of ACL reconstruction is associated with a lower risk of arthrofibrosis requiring intervention, particularly in patients aged 30 years or younger. [39] (10.1016/j.arthro.2023.01.102)
  • [L2] Acute ACLR within 8 days of injury does not appear to adversely affect ROM or result in increased stiffness in the knee joint when compared to delayed surgery. [40] (10.1007/s00167-017-4814-1)
  • [L3] Patients who have stiffness after primary TKA face significantly higher treatment costs for both operative and nonoperative treatments than patients who do not have stiffness. [41] (10.1016/j.arth.2022.10.040)
  • [L4] There were no significant differences between ACLR performed 10 days and ACLR performed at the 3-week point or after in terms of postoperative stiffness, Tegner scores, or reoperation for stiffness. [42] (10.1177/03635465231192987)
  • [Paper] Imaging of the knee is important for evaluating patients with knee pain, as the patellofemoral joint is a complex articulation dependent on both dynamic and static restraints for its function and stability. [47] (10.1016/j.csm.2014.03.007)
  • [L1] Arthrofibrosis, an uncommon yet significant complication following ACL reconstruction in children and adolescents, has a pooled prevalence of approximately 3.7%. [48] (10.1177/2325967126s00143)
  • [L3] [51] (10.1016/j.arth.2019.01.072)
  • [L3] Approximately 1 in 10 patients undergoing isolated arthroscopic ACLR and initiating supervised rehabilitation within 30 days after surgery received a diagnosis of arthrofibrosis within 12 months. [52] (10.1016/j.arthro.2024.12.004)
  • [L3] [53] (10.1177/036354659101900402)
  • [L1] Acute ACLR within 8 days of injury does not appear to adversely affect ROM or result in increased stiffness in the knee joint and was not inferior to the delayed group in any assessment when compared to delayed surgery. [54] (10.1007/s00167-019-05722-w)
  • [L3] Undergoing early ACL reconstruction within 6 weeks of ACL rupture does not increase the risk of arthrofibrosis. [55] (10.1016/j.jisako.2023.03.083)
  • [L2] The results of this study suggest that there is a distinct acute postoperative cytokine response profile in patients who develop stiffness 6 weeks after TKA, characterized by significant differences in levels of 9 cytokines over the first 2 postoperative days. [56] (10.1016/j.arth.2020.02.046)
  • [L4] The results indicated a significant effect of gender on knee kinematics in patients with arthrofibrosis after ACL reconstruction during weight-bearing knee flexion. [86] (10.1186/s13018-021-02729-3)
  • [L4] [92] (10.1186/s13018-016-0359-0)
  • [L3] [93] (10.1016/j.arth.2020.07.018)
  • [L4] However, the MUA could not restore normal patellar tilt of the arthrofibrotic knee. [95] (10.1186/s13018-024-05159-z)
  • [L3] Equivalent range-of-motion outcomes were seen between ALA, early MUA, and delayed MUA for the treatment of arthrofibrosis after TKA. [96] (10.5435/jaaos-d-22-00430)
  • [L4] MUA with LOA is an effective procedure likely to result in ROM and patient outcome scores similar to those of a nonarthrofibrotic knee after the same procedure. [102] (10.1177/2325967119864868)
  • [L3] These findings suggest that increasing obesity severity is not associated with higher rates of postoperative stiffness or inferior outcomes following MUA and that concern for stiffness alone should not serve as a categorical barrier to TKA or MUA when clinically indicated. [106] (10.1016/j.arth.2026.03.080)

See Also

References

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[3] Stiffness After Total Knee Arthroplasty. Journal of the American Academy of Orthopaedic Surgeons. 2004. DOI: 10.5435/00124635-200405000-00004

[4] Stiffness after Total Knee Arthroplasty. Journal of Knee Surgery. 2014. DOI: 10.1055/s-0034-1396079

[5] Stiffness After Total Knee Arthroplasty. Journal of Bone and Joint Surgery. 2005. DOI: 10.2106/jbjs.e-00345

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[7] Rotating-Hinge Revision Total Knee Arthroplasty for Arthrofibrosis Improves Motion Without Increasing Complications: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty. 2026. DOI: 10.1016/j.arth.2026.06.041

[8] Gravity‐Assisted Manipulation (GAM) Technique for the Treatment of Knee Arthrofibrosis. Arthroscopy Techniques. 2023. DOI: 10.1016/j.eats.2023.07.046

[9] Prevention of permanent arthrofibrosis after anterior cruciate ligament reconstruction alone or combined with associated procedures: a prospective study in 443 knees. Knee Surgery, Sports Traumatology, Arthroscopy. 2000. DOI: 10.1007/s001670000126

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[12] Arthroscopic arthrolysis for the treatment of stiffness after total knee replacement gives moderate improvements in range of motion and functional knee scores. Knee Surgery, Sports Traumatology, Arthroscopy. 2009. DOI: 10.1007/s00167-009-0878-x

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[22] Sulfasalazine Resolves Joint Stiffness in a Rabbit Model of Arthrofibrosis. Journal of Orthopaedic Research. 2019. DOI: 10.1002/jor.24499

[23] Static progressive stretch improves range of motion in arthrofibrosis following total knee arthroplasty. Knee Surgery, Sports Traumatology, Arthroscopy. 2009. DOI: 10.1007/s00167-009-0947-1

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[30] A Stepwise Approach to Arthroscopic Management of Recalcitrant Knee Arthrofibrosis Including Arthroscopic Posterior Capsular Release. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103646

[31] Arthrofibrosis of the knee: clinical result after early vs. late arthroscopic arthrolysis of 100 patients. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120s00307

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[34] Manipulation Under Anesthesia and Lysis of Adhesions Are the Most Commonly Reported Treatments for Arthrofibrosis of the Knee After Arthroscopy or Anterior Cruciate Ligament Reconstruction in Both Pediatric and Adult Patients. Arthroscopy, Sports Medicine, and Rehabilitation. 2024. DOI: 10.1016/j.asmr.2024.100896

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d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

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