Juvenile osteochondritis dissecans (JOCD) is a disorder

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1 EMILY A. EISMANN, MS 1 ROBERT J. PETTIT, BS 2 ERIC J. WALL, MD 1 GREGORY D. MYER, PhD 1,3-6 Management Strategies for Osteochondritis Dissecans of the Knee in the Skeletally Immature Athlete Juvenile osteochondritis dissecans (JOCD) is a disorder of the subchondral bone and overlying articular cartilage that most commonly affects the knee of active adolescents. Juvenile osteochondritis dissecans lesions are a unique articular joint pathology, initially involving the subchondral bone below the articular cartilage rather than the joint surface. 14 Specifically, the portion of the bone supporting the surface cartilage of the knee transforms into fibrous tissue, leaving the overlying joint articular cartilage susceptible to injury due to compromised bony support. 127 The presence of open growth plates distinguishes JOCD from the adult form of osteochondritis TTSYNOPSIS: Osteochondritis dissecans (OCD) is a disorder resulting in focal breakdown of the subchondral bone, with potential disruption of the overlying articular cartilage. The femoral condyles of the knee are the most common locations for OCD, and the incidence of OCD appears to be increasing among active children. Juvenile OCD (JOCD) can be distinguished from adult OCD by the presence of open growth plates. Due to a lack of evidence on its early diagnosis, optimal treatment, and long-term course of healing, JOCD presents a unique challenge for the health care team. Approximately 50% to 67% of stable JOCD lesions heal successfully with nonoperative treatment. For unstable lesions and stable lesions that fail nonoperative treatment, a variety of surgical interventions can be utilized to stimulate bony dissecans (OCD). 2,14,71 Though JOCD occurs most often in the knee joint, primarily in the medial and lateral femoral condyles, a few cases have been reported in the trochlear groove, patella, and tibial plateau. 57 The most common location healing and address articular cartilage lesions. It is recommended that rehabilitation of JOCD be tailored to the individual patient, based on the stage and radiographic status of the lesion and the mode of surgery employed when surgically addressed. Although there is a growing body of literature on this condition, the etiology and optimal methods for treatment, rehabilitation, and evaluating outcomes remain inconclusive due to a lack of quality evidence. TTLEVEL OF EVIDENCE: Therapy, level 5. J Orthop Sports Phys Ther 2014;44(9): Epub 6 August doi: /jospt TTKEY WORDS: children, femoral condyle, JOCD, juvenile, OCD, tibiofemoral joint of JOCD is on the lateral border of the medial femoral condyle, adjacent to the intercondylar notch (FIGURE 1). 47 The incidence of JOCD of the knee has been reported to be 8.7 per in children (6-11 years of age) and 21.8 per in adolescents (12-19 years of age), with higher incidence for boys than for girls. 57 The incidence in children under age 10 has been reported to have increased over the last 40 years from 2 per Described as early as 1870, 3,36,93 the underlying mechanism and prognosis for JOCD remain unclear. The comparative effectiveness of treatments for JOCD also remains unknown due to a lack of wellcontrolled studies. 1 Furthermore, clinical practice guidelines still need to be established regarding proper treatment of JOCD lesions based on relative size, location, stability of the lesion on magnetic resonance imaging (MRI), patient age, and status of growth plates. 19,20 Due to slow healing and extended period of sports participation restriction, JOCD can be a frustrating condition for the young athlete. 2 In cases with stable lesions, JOCD has been reported to heal most readily. 17,36,51 However, it is difficult to accurately predict who will heal from 1 Division of Orthopaedic Surgery, Cincinnati Children s Hospital Medical Center, Cincinnati, OH. 2 College of Medicine, University of Cincinnati, Cincinnati, OH. 3 Division of Sports Medicine, Cincinnati Children s Hospital Medical Center, Cincinnati, OH. 4 Department of Pediatrics and Orthopaedic Surgery, University of Cincinnati, Cincinnati, OH. 5 Sports Health & Performance Institute, The Ohio State University, Columbus, OH. 6 The Micheli Center for Sports Injury Prevention, Waltham, MA. No funding was obtained for this commentary. The authors certify that they have no affiliations with or financial involvement in any organization or entity with a direct financial interest in the subject matter or materials discussed in the article. Address correspondence to Dr Eric J. Wall, Division of Orthopaedic Surgery, Cincinnati Children s Hospital Medical Center, 3333 Burnet Avenue, MLC 2017, Cincinnati, OH eric.wall@cchmc.org t Copyright 2014 Journal of Orthopaedic & Sports Physical Therapy journal of orthopaedic & sports physical therapy volume 44 number 9 september

2 FIGURE 1. Radiograph of an osteochondritis dissecans lesion present in the medial femoral condyle of the knee. Note the appearance of lucency in the subchondral bone (arrow). nonoperative or operative treatment. Approximately 50% to 67% of JOCD lesions found during childhood will heal with 6 to 18 months of nonoperative treatments, which may include complete sports restriction, casting, bracing, and crutch walking. 17,18,100,124 Most authors agree that early diagnosis and treatment, before the child reaches skeletal maturity, produce the best long-term outcomes. 15,18,24,64 If left untreated, juvenile lesions can progress to adult forms of OCD, resulting in detachment or destruction of a portion of the joint surface and potentially leading to early osteoarthritis. 29 Thus, parents, coaches, athletic trainers, physical therapists, and physicians must be vigilant to identify JOCD and to initiate early treatment that will shorten recovery and improve outcomes in young athletes. ETIOLOGY The exact etiology of JOCD remains unknown. 111 Various authors suggest repetitive trauma, 14,47,51,64,123 ischemia, 36,51,93 and genetics 5,65,86,98,99,115,117 as the 3 most likely causes. Other factors may include leg malalignment 13,54 and the presence of a lateral discoid meniscus. 45,84,114 It is important to keep in mind that multiple factors may be working together to contribute to this condition. FIGURE 2. (A) The epiphysis has its own growth plate, which enlarges the secondary ossification center from birth to maturity and is seen on a high-resolution magnetic resonance image in this normal knee (arrows). (B) This secondary growth plate (arrows) usually disappears in the OCD lesion and may be responsible for the loss of bone formation in OCD. Failure to produce new epiphyseal bone may give rise to an OCD lesion. Abbreviation: OCD, osteochondritis dissecans. Repetitive Trauma Repetitive stress, especially in young athletes, is one of the most accepted causes of JOCD. 14,47,51,64,123 A majority of patients with OCD (55%-60%) are regularly involved in sports, 3,47 and repetitive cyclical stress through an athlete s joint may lead to chondral injury and possible vascular damage, leading to ischemia. 14 Laor et al 68,69 hypothesized that JOCD lesions could result from repetitive stress to the growth plate of the secondary ossification center that resides just between the surface cartilage and its supporting bone in the epiphysis of a growing athlete (FIGURE 2). Damage to the secondary growth plate could then disrupt new bone production. Although widely accepted, there is minimal research evidence to support repetitive trauma as the cause. Ischemia Ischemia, the loss of blood flow, was proposed as an etiological factor by Paget 93 in 1870, who described JOCD as a quiet necrosis. It was speculated that a loss of blood supply to the affected area may inhibit the tissue s ability to effectively re-form bone, resulting in cell death and separation of the bone from the cartilage. 36,51 It has also been proposed that OCD lesions may be filled with fibrocartilage resulting from deficient vascularization. 72 The many authors who have investigated the possibility of lesion development due to ischemia have found little supporting evidence. 3,4,23,107 However, some supporting evidence exists, including the ability to revascularize a partially attached lesion 81 and the presence of osteonecrosis in most histology studies (7/10). 111 Conversely, other studies have found a rich blood supply and no cell death in lesions of the medial femoral condyle. 3,4,23,107 Authors of a recent study on the viability of detached osteochondral fragments from 5 patients reported that 88% of chondrocytes (the cells found in cartilage) were viable, compared to 92% of chondrocytes in the healthy native cartilage. 96 This perhaps suggests that either OCD lesions are not a product of ischemia or the synovial fluid provides enough nutrition for the cells to remain viable. 96 Despite this controversy, the ischemia hypothesis has generated many current treatments for OCD, including drilling to produce revascularization for improved blood flow into the lesion. 9,95 Genetics Some authors theorize that genetics plays a role in the etiology of JOCD 666 september 2014 volume 44 number 9 journal of orthopaedic & sports physical therapy

3 FIGURE 3. AP and notch views of the same patient taken on the same day. (A) The OCD lesion (white circle) cannot be seen on the AP radiograph taken with the knee in full extension. (B) The OCD lesions are well visualized on the notch radiograph taken with the knee flexed. The black arrow is pointing toward the notch, which is lined in black. Abbreviations: AP, anteroposterior; OCD, osteochondritis dissecans. lesions; however, the exact molecular mechanisms and hereditary patterns are yet to be deter mined. 5,55,65,86,91,98,99,106,115,117 A study by Petrie 98 indicated a lack of familial inheritance of OCD, whereas Mubarak and Carroll 86 found an autosomal-dominant pattern. The literature does not yield conclusive evidence regarding the contribution of specific gene products to the development of a lesion. Limb Malalignment Malalignment of the lower limb intuitively makes sense in the context of mechanical-axis deviation, as a change in the forces through the joint would increase strain on specific aspects of the joint. A study by Jacobi et al 54 identified the presence of mechanical-axis deviation in both adolescents and adults with knee OCD. Valgus alignment was associated with lateral condyle lesions, whereas varus alignment was associated with medial condyle lesions, although the amount of valgus/ varus remained within normal physiological ranges. 54 This increased loading on the affected knee compartment may have implications for the use of an unloader brace. A smaller medial tibial slope has also been identified in adult OCD lesions. 112 The impact of mechanical loading from the hip and foot on knee JOCD has not been evaluated. DIAGNOSIS Most experts agree that diagnosis and treatment of JOCD at an early stage are optimal for healing. 15,18,24,64 Unfortunately, most patients are diagnosed with JOCD a year or more after the onset of symptoms. 15,123,124 This delay in diagnosis is largely due to the nonspecific nature of the early symptoms and the nonspecific findings on physical exam. Nonspecific knee pain is the most common early symptom, reported by 80% of individuals with JOCD. 15 Although not as common, other possible symptoms include effusion (fluid in the joint), catching, locking, giving way, muscle atrophy, increased sensitivity, and specific tenderness. 15,64,123 The potential presence of JOCD is camouflaged among the many benign juvenile knee-pain conditions, such as jumper s knee, the Osgood- Schlatter condition, and patellofemoral pain syndrome. Wilson s sign, which measures the pain produced from extending the knee while internally rotating the tibia, is no longer considered a reliable or specific test for JOCD. 24,25 Unfortunately, an effective clinical exam for JOCD has yet to be identified and validated. Therefore, clinical diagnosis currently relies on plain radiographs and MRI. 123 FIGURE 4. A T2 MRI showing an osteochondritis lesion affecting the posterior portion of the femur with a significant articular cartilage fissure (arrow). An important distinction between radiograph and MRI is the MRI s ability to assess cartilage damage. Abbreviation: MRI, magnetic resonance image. Radiographs Radiographs are useful to visualize subchondral involvement of a JOCD lesion in the femoral condyle; however, the sensitivity and specificity of radiographs for diagnosis have never been evaluated. On radiographs, most JOCD lesions appear as a dark, bone-deficient area just beneath the cartilage surface. 16,44 Due to their frequent posterior location, many JOCD lesions can only be visualized on a tunnel or notch-view radiograph. Standard anteroposterior and lateral radiographs are often insufficient to diagnose JOCD lesions and often do not illustrate articular cartilage injuries, small lesions, or lesions of the patellofemoral joint (FIG- URE 3). 17,31,47,123 Unless a loose body is seen, radiographs do not show whether the surface cartilage of the JOCD lesion is stable or unstable, which is critical in treatment decision making. The diagnostic accuracy of the combination of radiographs with medical history and physical examination has been found to have a sensitivity of 77% and specificity of 98%. 61 Magnetic Resonance Imaging Magnetic resonance imaging (FIGURE 4) is the diagnostic method of choice for assessing the supporting bone and cartilage quality of a JOCD lesion, which journal of orthopaedic & sports physical therapy volume 44 number 9 september

4 TABLE Common Osteochondritis Dissecans Lesion Classification Systems FIGURE 5. Arthroscopy view of the knee s femur cartilage surface showing a detached osteochondritis dissecans lesion that has separated from its crater. may appear normal on plain radiographs and arthroscopy. The articular cartilage that covers the joint surface of the femur and tibia in the knee can be visualized on MRI as a smooth, gliding surface. Magnetic resonance imaging also enhances the visibility of bone cysts, subarticular high-signal lines, and articular cartilage fissures that may affect prognosis and treatment. 30 For identifying JOCD knee lesions, MRI has been found to have a sensitivity ranging from 78% to 100%, a specificity ranging from 95% to 100%, and an accuracy of 100%. 61,73 These findings for MRI are similar to those for radiographs and physical examination combined. 61 Typically, all 3 methods are used for diagnosis and to make treatment decisions. Arthroscopy Arthroscopy is the gold standard for assessing the status of the joint s surface cartilage, including the shape, strength, continuity, fissuring, softening, and detachment of the JOCD lesion (FIGURE 5). Unfortunately, the joint surface may show no abnormality in many JOCD cases, making MRI more sensitive for earlystage lesions. Limited quality evidence is available on the level of agreement between MRI and arthroscopy for the diagnosis of knee JOCD, 101 with 1 study indicating a moderate level of agreement (κ = 0.70) 73 that improved with the addition of information on the medical history, clinical exam, and plain radiographs (κ = 0.90). 73 System Berndt and Harty 7 Stage I Stage II Stage III Stage IV Hefti et al 47 Stage I Stage II Stage III Stage IV Stage V Dipaola et al 30 Stage I Stage II Stage III Stage IV Chen et al 21 Stage I Stage II Stage III Stage IV Stage V Guhl 39 Stage I Stage II Stage III Stage IV Ewing and Voto 35 Grade I Grade II Grade III Grade IV Classification CLASSIFICATION Classification using radiographs Compression of subchondral bone Partially detached fragment Nondisplaced fragment that is completely detached Completely detached and displaced fragment Classification using magnetic resonance imaging Small signal change; fragment not clearly outlined Clearly outlined fragment; no fluid Partially visible fluid between fragment and bone Fluid surrounding fragment Detached and displaced fragment Classification using magnetic resonance imaging Articular cartilage thickening; low signal changes Articular cartilage breached; low signal rim behind fragment Articular cartilage breached; high signal rim behind fragment Loose body Classification using gradient-echo magnetic resonance imaging Intact overlying cartilage; no demarcated interface Low-signal fragment-donor interface; partial cartilage tear High-signal fragment-donor interface; partial or complete cartilage tear Low- or intermediate-signal fragment-donor interface; decreased signal line through overlying articular cartilage Focal fluid-filled osteochondral crater Classification using arthroscopy Irregularity and softening of articular cartilage; no fragment Articular cartilage breached; not displaceable, definable fragment Articular cartilage breached; attached but displaceable fragment Loose body Classification using arthroscopy Intact lesion Lesion demonstrating early separation Lesion partially attached Loose fragment in joint A comprehensive classification system for JOCD that incorporates information from radiographs, MRI, arthroscopy, and clinical evaluation has yet to be validated, but various methods have been employed to characterize the size, severity, and stability of JOCD lesions. Radiographs Although commonly used for diagnosis, plain radiographs are not recommended for classification of JOCD lesions. A staging system has been developed by Berndt and Harty 7 (TABLE), but, when evaluated, plain radiographs were incorrectly staged for all but 1 medial femoral condyle lesion when compared to arthroscopy. 30 Furthermore, plain radiographs do not adequately show disruptions in the articular cartilage or whether the lesion is attached to the underlying bone for accurate staging. 90 While not optimal for staging, radiographs are used extensively to assess healing progression. 668 september 2014 volume 44 number 9 journal of orthopaedic & sports physical therapy

5 FIGURE 6. Magnetic resonance image showing a high-signal line (arrow) at the interface between the osteochondritis dissecans lesion and its bed. This likely indicates an early deep separation at the bone-cartilage junction, which would not be seen on arthroscopy. Magnetic Resonance Imaging Magnetic resonance imaging is much more accurate and useful than radiographs for classifying the stability of JOCD knee lesions. De Smet et al 26 provided the first system for assessing stability of a JOCD lesion using T2- weighted MRI. The 4 signs of instability include (1) a focal osteochondral defect filled with joint fluid, (2) an articular fracture, (3) an adjacent fluid-filled subchondral cyst of 5 mm or greater in diameter, and (4) a line of high signal intensity between the lesion and underlying bone. 26 Some authors suggest that the high-signal line may indicate that synovial fluid has seeped under the lesion through a break in the surface cartilage, 30,79,88,90 whereas others suggest that the line may represent vascular granulation and healing of the fibrovascular tissue. 8,129 This line of high signal intensity may not always correlate with instability on arthroscopy, perhaps because arthroscopy cannot visualize a nonarticular deep separation between the lesion and the underlying bone (FIGURE 6). 90 Using the De Smet et al 26 classification system, MRI has been found to have a sensitivity of 100%, but a specificity ranging from only 11% to 15%. 48,58 Hefti et al 47 and Dipaola et al 30 have also developed MRI staging systems (TABLE). The accuracy of the FIGURE 7. The authors interpretation of lesion classification based on the same criteria as Ewing and Voto. 35 (A) A grade I OCD lesion. The top picture represents the femur surface with articular cartilage that would be seen during arthroscopy. The bottom picture illustrates the appearance on a magnetic resonance image scan that depicts both the supporting bone and the articular cartilage. The lesion represented by a black arc is contained only within the subchondral bone. (B) A grade II OCD lesion with a partial fissure of the surface cartilage. (C) A grade III OCD lesion that has complete fissure in the surface cartilage but remains in its bed. (D) An OCD fragment that has broken loose, leaving behind a crater, is categorized as grade IV. Abbreviation: OCD, osteochondritis dissecans. Dipaola et al 30 staging system ranges from 30% to 83% for knee OCD when compared to arthroscopy, with lower accuracy for younger patients. 30,48 Chen et al 21 proposed another staging system using 3-D, T1-weighted, gradient-echo MRI in combination with routine MRI (TABLE) and found 83% to 90% agreement between MRI and arthroscopy. They also reported 100% sensitivity, 100% specificity, and 100% accuracy for detection of OCD instability. 21 The accuracy of MRI can depend on the strength of the magnet, the imaging sequence, the use of a dedicated knee coil, and the expertise of the radiologist. 8,10 Based on a recent systematic review, there is not enough quality evidence to offer conclusive guidelines on the clinical utility of MRI for diagnosis and staging of JOCD. 101 Arthroscopy The most widely used arthroscopy grading systems were proposed by Guhl 39 and Ewing and Voto 35 (TABLE, FIGURE 7). While many systems exist for lesion classification, determining the stability of the articular cartilage and the attachment/detachment of the fragment to the subchondral bone is thought to be the most important factor for guiding treatment. 64,96 PROGNOSTIC FACTORS The most useful criteria in determining the prognosis of a lesion may be its size, location, sclerosis, and the patient s age or skeletal maturity. 17,47,66,100,102,124 Authors agree that younger patients and those exhibiting open growth plates show the greatest potential for healing by nonoperative methods. 27,47,51,66,121,124 Lateral femoral condyle lesions in the non weight-bearing region have 15.7 times greater odds of being unstable 109 and are less likely to heal 47 than medial femoral condyle lesions. FIGURE 8 presents a nomogram developed from the regression analysis with a case-control series that can be used to predict a patient s outcome based on normalized width, normalized length, and symptoms. 124 FIGURES 9 and 10 provide examples of how lesion size is measured and how it corresponds with the probability of a healing or failing outcome. This nomogram was found to be 80% sensitive and 57% specific. 66 Another nomogram has been developed that identified younger age, narrower normalized lesion width, and smaller cyst-like lesion size as predictors of healing after 6 months of nonoperative treatment. 66 This nomogram was 60% sensitive and journal of orthopaedic & sports physical therapy volume 44 number 9 september

6 Points Normalized length, % Normalized width, % Symptom category Total points Probability of healed Mechanical (II) % specific. 66 Although lesion stability typically dictates whether a patient will be treated operatively versus nonoperatively, little evidence is available to support this convention. 19,20 NONOPERATIVE TREATMENT Activity Restriction Juvenile osteochondritis dissecans lesions are typically managed with an initial trial of nonoperative treatment involving restriction of physical activity and/or weight bearing. 15,25,28,46,124 Patients are instructed to stop activities that cause repetitive stress to the affected joint, including all contact sports, running, jumping, excessive squatting, long periods of standing, and compressive stress to the joint (eg, skiing, skateboarding). It is often difficult for patients to comply with these recommendations. 15 For this reason, it is beneficial for the physician and therapist to offer alternative forms of exercise. For some athletes, this may be an opportunity to supplement their lifestyle with nonimpact activities or to work on Isolated Pain (I) FIGURE 8. This nomogram can be used to predict a patient s outcome based on the normalized width and length of his or her osteochondritis dissecans lesion and its associated symptoms. To use the nomogram, place a straight edge vertically so that it touches the designated variable on the axis for each predictor. Record the value that each of the 3 predictors provides on the points axis at the top of the diagram. Sum all of the recorded points and locate this value on the total points line with a straight edge. Follow a vertical ruler line down from the total points line to the probability line, which is the probability that the patient will heal after 6 months of conservative treatment based on the utilized predictive variables. Figure reproduced with permission from Wall EJ et al 124 ( fundamentals of their sport that do not require impact (eg, free-throw shooting in basketball). If the physician/therapist is allowing weight bearing, athletes may be able to stay in shape by seeking other forms of exercise, including swimming, deep-water running, stationary bike, or elliptical machine. 34,53,66,104 A basic science study suggests that shearing forces, such as those produced by the stationary bike and elliptical, may facilitate articular cartilage healing better than compressive forces. 122 However, there is no available evidence on the effectiveness of these forms of exercise for JOCD. Pain and effusion can be managed with cryotherapy 105 and electrical stimulation. 113 Immobilization Patients may also be immobilized for 4 to 16 weeks to alleviate pain and mechanical symptoms and to allow the knee to rest from repetitive stress to the joint surface. 4,36,66,124 Immobilization may include partial weight bearing in a cylinder or long-leg cast, 124 a hinged brace, 92,124 and/ or the use of crutches or other ambulatory aids. 15,66 Some studies suggest serial casting every 4 to 6 weeks until healing is evident on radiographs. 124 Evidence is currently unavailable as to which approach is best. A hinged brace that stabilizes and aligns the knee in valgus can shift the stress off the medial compartment, whereas a hinged brace that aligns the knee in varus can shift the stress off the lateral compartment (FIGURE 11). 92,124 Preliminary evidence in healthy adults suggests that valgus unloader braces may be effective at realigning the knee and decreasing adduction while walking in patients with medial compartment pathology. 92 Allowing for some weight bearing and passive motion has been shown to improve articular cartilage repair in animal studies, 12,43 as cartilage may become more vulnerable after complete immobilization. 49,89 Specific guidelines for the duration of immobilization and the extent of allowed range of motion and weight bearing have not been established. 19,20 Rehabilitation No widely accepted or validated rehabilitation protocol exists for patients with JOCD. Our institutional guidelines, 110 which were formulated based on experience, consensus, and the literature for related knee conditions, have established baseline criteria for pain and effusion, weight bearing, range of motion, muscle performance, and neuromuscular control to determine when to advance a patient to greater weight bearing. Mechanical symptoms 66 and radiographic healing 124 have also been used. During the initial phase, striving for a normal range of motion, equal to the contralateral side, is beneficial for healing and is accomplished through passive range-of-motion exercises and stretching. 104 Although controversial, basic science studies suggest that the use of controlled range-of-motion exercises, either through a continuous passive motion device or repetitive active assisted range of motion, may help to nourish the articular cartilage surface and promote a healthy knee joint. 11,56,59,104 Once full passive range of motion and 670 september 2014 volume 44 number 9 journal of orthopaedic & sports physical therapy

7 partial weight bearing are achieved, the patient can be progressed to the intermediate phase, with active range-ofmotion exercises, muscle strengthening, and balance training. 126 Neuromuscular electrical stimulation of the quadriceps muscles 113 and weight-bearing and non weight-bearing activities or progressive resistive exercises 126 can facilitate muscle strengthening. Increasing strength with a focus on the lower extremity and core musculature serves as a stabilizing force to protect the joint and dampen forces around the joint. 104 Balance activities are critical to restore normal proprioceptive feedback from the knee joint. 126 Once full active range of motion and weight bearing are achieved, the patient is progressed to the advanced phase and should begin running and gradually proceed to impact and sport-specific activities, as tolerated. 110 OPERATIVE TREATMENTS A recent systematic review identified a lack of consistency on the indications for operative treatment of JOCD lesions, with 40% of studies not providing clear indications and 60% recommending surgery after failure of nonoperative treatment. 108 Proposed treatment algorithms, however, offer many recommendations. 33,95 For stable JOCD lesions without loose bodies, 3 to 12 months of nonoperative treatment is recommended, followed by drilling if the lesion remains unhealed. 33,124 Approximately 50% to 67% of JOCD lesions heal in 6 to 18 months with nonoperative treatment, and thus do not require surgery. 17,18,100,124 For unstable or displaced lesions with salvageable fragments, fixation with or without drilling or microfracture is recommended. For unsalvageable fragments, immediate operative treatment is recommended, but the technique varies based on lesion size and demand. 33 Although these recommendations have been made, the literature is currently inconclusive on the comparative effectiveness of treatment for JOCD. 1,19,20,119 FIGURE 9. Example of a representative patient s calculated probability to achieve healed status using the nomogram based on normalized length of the lesion (0.52), normalized width of the lesion (0.19), and reported symptoms (mechanical). The patient was predicted to have a 21% chance of healing under nonoperative treatment. The presented patient did not achieve healed status after 6 months of nonoperative treatment. Figure reproduced with permission from Wall EJ et al 124 ( Drilling The goal of arthroscopic drilling is to increase revascularization and reossification of the JOCD lesion to facilitate bone healing. 4,10,13,46 The surgeon can drill the JOCD lesion directly through the surface cartilage (transarticular technique) or indirectly from behind the joint surface (retroarticular technique). 40 Both drilling techniques are minimally invasive and create bone tunnels into the lesion using a Kirschner wire or a drill bit. The transarticular technique penetrates the articular cartilage through small drill holes. However, these small drill holes in the articular cartilage may not heal even a year later. 40 By drilling from behind the cartilage, the retroarticular technique (FIGURE 12A) avoids making small holes through the articular cartilage surface. The retroarticular technique, however, is more technically difficult than the transarticular technique and may raise the risk of incomplete JOCD drilling, overpenetration into the joint, or injury to soft tissue or saphenous nerve. 40 The number of holes drilled is dependent on the size of the lesion. 62 The most widely used operative treatments for stable JOCD lesions are retroarticular and transarticular drilling, 1 which have a success rate of 75% journal of orthopaedic & sports physical therapy volume 44 number 9 september

8 FIGURE 10. Example of a representative patient s calculated 93% probability to achieve healed status using the nomogram based on normalized length of the lesion (0.17), normalized width of the lesion (0.14), and reported symptoms (isolated pain). The presented patient achieved healed status after 6 months of nonoperative treatment. Figure reproduced with permission from Wall et al 124 ( to 100%. 32,62 To improve healing, it has been proposed that the retroarticular drilling tunnels be filled with bone cells and bone-forming stem cells from iliac crest bone marrow that are percutaneously harvested from the patient s hip with a bone biopsy needle (FIGURES 13A and 13B). 75 This procedure is indicated for lesions that are not mobile, incongruent, or displaceable and may help to stimulate healing of the JOCD lesion versus drilling alone and to avoid damage to the stable articular cartilage. 75 The effectiveness of this technique has not been evaluated. Drilling is typically followed by a period of non weight bearing, rehabilitation, and return to sports after 3 to 4 months if healing is evident on radiographs. 18 Microfracture Microfracture, which uses an awl to create tiny fractures in the subchondral bone, has also been suggested to facilitate the influx of stem cells and growth factors for cartilage resurfacing. 37,38,53 Microfracture is typically performed on lesions with complete discontinuity down to the subchondral bone, a loose fragment, or a displaced fragment. 38 The remaining unstable or necrotic bone in the lesion is removed prior to microfracture. 38 One study identified good to excellent results in 86% of JOCD lesions FIGURE 11. An offloading brace used to protect a lateral femoral condyle OCD lesion. The bulky pad on the medial side of the brace (arrow) applies pressure (a varus stress), partially relieving the affected lateralside OCD lesion. Abbreviation: OCD, osteochondritis dissecans. treated with microfracture at 1 year that reduced to 63% by 4 years 38 and 62% by 10 years. 37 This finding highlights the importance of long-term follow-up, as short-term outcomes may regress over time. An animal study, however, found that microfracture created dense bone compaction around the fractured holes and osteocyte necrosis that might have impeded repair, whereas drilling cleanly removed the bone and created channels for bone marrow influx without signs of necrosis. 22 Fixation Bioabsorbable or metal pins and screws can also be used to reattach a partially or completely detached JOCD lesion (FIG- URE 12B). 65 Fragment fixation has been reported to have a similar success rate to drilling (75%-100%) based on radiographs, 60 MRI, 29,78 or both. 118,125 Studies have also shown significant improvement in functional outcomes 60,77,78 and patient satisfaction. 29 Fragment fixation can also include bone grafting between the OCD lesion and its bed, along with curettage 672 september 2014 volume 44 number 9 journal of orthopaedic & sports physical therapy

9 FIGURE 12. (A) Illustration of retroarticular drilling of the subchondral bone. This technique drills from behind the lesion, thereby avoiding harm to the articular cartilage. (B) Illustration of fixation of the loose body with metal pins to the bone. FIGURE 13. (A) Harvesting of bone from the hip and (B) insertion of bone graft percutaneously into the osteochondritis dissecans lesion to promote healing. and drilling of the recipient bed. 75 The effectiveness of these techniques has not been established. Excision and Implantation If the OCD lesion is smaller than 1 cm in diameter, it may be removed and the bed perforated with a drill or a pick to stimulate repair cartilage in-growth. 4,35 Fragment excision, however, has been reported to have a relatively low success rate (25%-53%), along with an increased risk of osteoarthritis. 4,47 Larger lesions that are irreparable can also be reconstructed with osteochondral autograft/allograft plugs (83%-100% success rate) 37,38,76,83,85,87 or autologous chondrocyte implantation (82% success rate) 67,80 (FIGURES 13A and 13B). Realignment Surgery Varus and valgus malalignment of the knee has been reported in patients with medial and lateral condyle JOCD lesions, respectively. 54 If the patient is skeletally immature, guided growth is a minimally invasive, minimally painful procedure to realign the knee. 116 Guided growth can harness the power of the growth plate to correct the knee deformity. Screws, staples, or a screw-plate device are inserted across one side of a growth plate, which slows the growth under the device and allows full growth on the side of the knee that is opposite the device (FIGURE 14). 74 This can gradually correct a varus or valgus knee deformity after only a few months if the patient is still growing. If the patient has completed growth, then the bone can be cut and realigned with a metal plate or an external fixator, which is a much more invasive procedure than guided growth in the growing patient. 82 Rehabilitation There are few evidence-based recommendations in the literature for postoperative rehabilitation following surgical interventions for JOCD lesions of the knee. Studies have reported prescribing 4 to 12 weeks of non weight bearing following osteochondral autologous transplants, 37 microfracture, 37 fixation, 60,77,78 and transarticular drilling, 128 and 6 to 12 weeks of partial or touch-down weight bearing for fixation 118 and osteochondral allografts. 76 Full range of motion has been allowed immediately following fixation and drilling procedures. 77,78,128 Unloader braces have been recommended to help resume weight bearing and mobility, while protecting the knee from overload. 92 Preliminary evidence in healthy adults suggests that valgus unloader braces may be effective at realigning the knee and decreasing adduction while walking in patients with medial compartment pathology. 92 Studies of adults with osteoarthritis suggest that a brace may decrease pain and improve strength and activity, but might not impact joint space or knee kinematics. 42,52 The effectiveness of bracing and activity modification for knee JOCD has yet to be established. 19,20 Furthermore, when considering forms of immobilization, health care providers should be cognizant of the findings from animal studies suggesting that long-term immobilization may have a negative impact on articular cartilage that may not be reversible. 6,41 The goal of the initial phase of postoperative rehabilitation is to restore full range of motion, maintain quadriceps function, and reduce joint swelling, which can be achieved through passive rangeof-motion exercises, straight leg raises, cryotherapy, and gradually advancing to the stationary bike and deep-water running. 53 Continuous passive motion has also been recommended 53 but is not often used following surgery. 37,76,77 The decision to advance toward weight bearing should be made by the therapist and physician together and be based on reductions in pain, swelling, and stiffness as well as signs of radiographic healing. Once the patient achieves full range of motion and weight bearing after about 2 months, the journal of orthopaedic & sports physical therapy volume 44 number 9 september

10 FIGURE 14. (A) Preoperative and (B) postoperative radiograph showing guided growth screws placed after fixation of a medial compartment OCD lesion. The guided growth screws correct knee alignment as growth continues by offloading pressure on the healing OCD lesion. Abbreviation: OCD, osteochondritis dissecans. goal is to restore muscle function through weight bearing; double-leg exercises with flexion up to 30 ; and progressive stationary biking, deep-water running, and elliptical and treadmill walking. 53 After 4 to 6 months, the patient may transition to a staged running program and, after 6 months, to sport-specific activities such as pivoting, cutting, and jumping. 53 Impact should be reduced if the patient exhibits signs of persistent effusion, localized pain, and loss of motion. 53 Older patients and patients with greater damage to their articular cartilage may require more time to rehabilitate. 104 The treatments described above may allow for additional protection to the healing lesion; however, it is critical to avoid applying high compressive loads to the healing tissue until radiographic evidence of healing and sufficient neuromuscular control suggest that the patient is prepared to handle more rigorous activity and strain. The authors of this article recommend that a safe zone, defined as the arc of motion in which the tibia does not contact the femur JOCD lesion, be determined from the preoperative MRI scan. Basic science studies suggest that reducing contact stress during joint motion may help to stimulate restoration of the articular surface. 11 If the patient s MRI evidence shows that a certain range of motion will not apply stress to a healing lesion, the rehabilitation specialist may tailor full weight-bearing and progressiveresistance exercises within this safe range of motion (FIGURE 15). This may allow safe, progressive exercises for the quadriceps, hamstrings, and gastrocnemius with increasingly stronger resistance. RETURN TO SPORT The healing process for JOCD can be frustratingly slow for all parties involved; however, premature return to activity can be devastating. The decision to return to sports is a collective one, involving the patient, health care team, and patient s family. Return to sports typically occurs about 6 months after surgery, 37,128 but premature return to sport with residual pain, strength impairments, or altered movement patterns following nonoperative or operative treatment can result in damage to healing tissues or nonhealing of the JOCD lesion. Rauh et al 103 reported that prior injury was a primary risk factor for future injury in young athletes. In addition, Paterno et al 97 reported a high incidence of second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and identified altered movement patterns as predictive factors for second injury. In addition to complete healing on radiographs or MRI, 66,124 a criteria-based progression for return to sport following nonoperative or operative treatment should include full range of motion, no pain, 90% strength, normal agility, and no limp. 110 The physician and the rehabilitation team must work together closely to provide a consensus opinion of the optimal, evidence-based time frame for returning to sports. RADIOLOGIC OUTCOMES Radiographs are most often used to evaluate JOCD lesion healing. 4,17,18,32,47,60,62,76,87,100,124 However, a few studies have used MRI. 29,66,78,83,85,118,125 Success rates have ranged from 50% to 67% for nonoperative treatment, 17,18,100,124 75% to 100% for retroarticular and transarticular drilling, 32,62 75% to 100% for fixation, 29,60,78,118,125 62% to 86% for microfracture, 37,38 83% to 100% for osteochondral autograft/allograft plugs, 37,38,76,83,85,87 82% for autologous chondrocyte implantation, 67 and 25% to 53% for fragment excision. 4,47 Although these studies used radiographs and MRI, the accuracy and reliability of these modalities have not been compared, and a valid and standardized measure for determining JOCD healing has not been established. Some studies define healing as radiographic union of the JOCD lesion with the underlying bone and/or clinical resolution of 674 september 2014 volume 44 number 9 journal of orthopaedic & sports physical therapy

11 symptoms. 60,118 Classifying JOCD healing based on a single follow-up radiograph has been found to have fair reliability (interrater kappa of 0.44, intrarater kappa of 0.68). 94 To improve reliability, it has been suggested that the percentage of healing be evaluated across a series of radiographs. 32 Unfortunately, slight differences in the radiographic technique used at each visit can lead to a false positive impression of healing. Serial radiographs can also increase radiation exposure; however, the effective dose of radiation for a knee radiograph in children ranges from to 0.19 mrem, 50 which is minimal considering that the average exposure from natural sources (eg, radon) per year in the United States is 300 mrem. 120 An MRI scan or needle biopsy may give the most definitive evidence of healing. On MRI, healing has been defined by an absence of a sclerotic rim at the interface between the osteochondral fragment and subchondral bone. 29,78,102 Magnetic resonance imaging, however, is more expensive than radiographs, and a biopsy requires a second surgery. FUNCTIONAL OUTCOMES Many validated measures have been used in recent years to assess the functional outcomes of patients with knee JOCD and the effectiveness of treatment. 119 The most common questionnaires are the International Knee Documentation Committee Subjective Knee Evaluation Form, 4,51,60,78,125 the International Cartilage Repair Society scale, 37,38,67,78,125 the Hughston Clinic Knee Questionnaire, 4 the Lysholm knee score, 9,60,78,128 the Knee injury and Osteoarthritis Outcome Score, 77,95 the Tegner activity scale, 9,37,60,125 and the Marx activity scale. 77 There is now a validated pediatric version of the International Knee Documentation Committee Subjective Knee Evaluation Form available for clinicians and researchers as well. 63 In addition to evaluating surgical treatments, these questionnaires may be helpful tools for physical therapists to evaluate patients as they progress through FIGURE 15. Safe zones of knee motion can be prescribed by looking at the location of the OCD lesion on the lateral radiograph and sagittal magnetic resonance image. In this example, full knee extension has full OCD contact with the tibia, whereas knee flexion beyond 90 gives minimal contact between the OCD lesion and the tibia, making full weight-bearing and strengthening exercises safe within the arc of motion between 90 and 135. Abbreviation: OCD, osteochondritis dissecans. rehabilitation and to compare the effectiveness of different approaches. CONCLUSION The incidence of JOCD has increased in children under age 10 in recent years, with a large percentage involved in sports. 3,47,57,70 The development of a universal classification system that aids in prognosis and treatment decision making is paramount to the proper treatment of this condition. Nonoperative treatment of JOCD is successful in approximately 50% to 67% of stable lesions. For unstable lesions, and those stable lesions that fail to heal with nonoperative treatment, a variety of surgical interventions are utilized, with healing success rates of 62% or greater for all treatments except fragment excision. 4,29,32,37,38,47,60,62,67,76,78,83,85,87,118,125 Research on nonoperative and postoperative rehabilitation is currently limited and insufficient for evidence-based recommendations. We suggest the use of safe zones as a means of protection for the healing tissue. It is also recommended that return to sports activity be based on whether the patient demonstrates healing on radiographs or MRI and has full range of motion and agility, near full strength, and no pain or limp. Several validated outcome questionnaires exist for children with knee conditions and may be useful tools for health care professionals to evaluate, compare, and advance the different treatment and rehabilitation approaches to JOCD. t REFERENCES 1. Abouassaly M, Peterson D, Salci L, et al. Surgical management of osteochondritis dissecans of the knee in the paediatric population: a systematic review addressing surgical techniques. Knee Surg Sports Traumatol Arthrosc. journal of orthopaedic & sports physical therapy volume 44 number 9 september

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