Treatment Algorithm for Osteochondritis Dissecans of the Knee

The authors’ preferred treatment algorithm for osteochondritis dissecans (OCD) of the knee is based on skeletal maturity, OCD lesion stability, and OCD lesion salvageability. For unstable yet salvageable OCD lesions, the senior author’s preferred treatment is fixation with bone grafting. For unstable and unsalvageable OCD lesions, the senior author’s preferred treatment is autologous chondrocyte implantation with bone grafting.

Key points

•

Determining skeletal maturity as well as osteochondritis dissecans (OCD) lesion stability and salvageability are important to any OCD treatment algorithm.
•

Given the paucity of high-quality studies of OCD treatment, algorithmic protocols are based on expert opinion, primarily.
•

Future research in the management of OCD through high-quality studies will help elucidate the most effective and appropriate treatment management strategies for OCD.

Background

The cause of osteochondritis dissecans (OCD) has been perplexing for more than 130 years. Since Konig’s early description of OCD, numerous hypotheses have abounded. These hypotheses include trauma, genetics, inflammatory causes, and vascular abnormalities. However, no single hypothesis has gained consensus agreement in the orthopedic community. Nonetheless, given the increased incidence of OCD in the athletic population, most in the sports medicine community agree that repetitive microtrauma plays at least some role in the cause of the development of an OCD lesion.

This popular theory of microtrauma gained support because the classic location of OCD of the knee is on the lateral aspect of the medial femoral condyle. As described by Fairbanks, OCD lesions in this classic location are possibly caused by repetitive impingement against the prominent tibial spine. This theory had gained support by Nambu and colleagues’ biomechanical study showing that vigorous exercise may produce trauma resulting in bone collapse of the medial femoral condyle. This theory does not account for OCD lesions developing outside this classic location of the knee in athletes.

Given the relatively low incidence of OCD of the knee, historically, it has been difficult to perform high-quality, prospective, comparative studies to ascertain the best available treatment options for those suffering from OCD. Most of the available literature on treatment has been retrospective in nature or small case series. However, many techniques for managing OCD lesions have been described, and options for management differ depending on several variables, including status of the physis, location of the lesion, stability of the lesion, and salvageability of the lesion.

This article provides a detailed discussion of the treatment options available for OCD in the athlete and includes a proposed treatment algorithm based on the senior author’s experience.

Clinical presentation and physical examination

The presentation of OCD of the knee is variable. The variability of the signs and symptoms is caused by the stage of the lesion when they present. A stable lesion that remains in situ likely presents as nonspecific knee pain that is poorly localized by the patient, externally rotated gait pattern, and a possible effusion. Comparatively, a lesion that has progressed to instability may become a loose body and present with mechanical symptoms, including a catching or locking sensation. Anecdotally, we believe these symptoms are exacerbated by increased physical activity.

The athlete may be observed to ambulate with minimal antalgia. The knee may have an effusion. There may be some point tenderness. For the classic lesion, point tenderness localizes to the distal aspect of the medial femoral condyle with the knee flexed to 90°.

Imaging

The importance of imaging in diagnosing and characterizing OCD lesions is well established and the goals of such imaging should be to identify, characterize, and stage the lesion as well as to follow healing. Initial imaging of the knee should begin with plain radiographs : weight-bearing anteroposterior, lateral, sunrise (merchant), and weight-bearing tunnel views. From the radiographic series, the lesion can be localized and measured, morphology described, and patency of the physes recorded.

Magnetic resonance imaging (MRI) has become the preferred imaging modality for further assessing and characterizing OCD lesions of the knee. There are a few classification systems to stage OCD lesions based on particular MRI findings. These MRI findings include a distinct OCD fragment, high T2 signal intensity observed between the parent and progeny bone, disruption in the cartilage interface between the parent and progeny bone, and loose bodies. The authors recommend MRI for characterization of all OCD lesions in the athletic population.

Treatment options for OCD in the athlete

Conservative Management

In 1985, Bernard Cahill makes a clear distinction between the successful outcomes of juvenile OCD (JOCD) and the adult form (AOCD) stating, “JOCD and [AOCD] are distinct conditions. The former has a much more favorable prognosis than the latter.” The current terminology favors the use of skeletally immature and skeletally mature over the terms JOCD and AOCD, respectively. In 1989, Cahill and colleagues reported that approximately half of patients with skeletally immature OCD of the knee in the athletic population go on to heal using conservative management. Others have reported greater rates of healing (81%) in similar athletic populations treated conservatively.

In skeletally immature athletes with symptomatic yet stable OCD lesions, the senior author’s preferred treatment is nonoperative. Specifically, the in-season athlete may wear an unloader brace to minimize weight bearing through the involved compartment of the knee. Otherwise, a cylinder cast can be applied for 6 weeks to minimize loading and shearing of the OCD lesion. Either way, it is important to communicate to the athlete and family that the key for these treatments is to eliminate pain. If pain is not eliminated, then the OCD lesion does not heal. Healing can subsequently be assessed on radiographs and MRI.

Despite the success of nonoperative management seen in the juvenile population, similar results are not echoed in the adult population. Skeletally mature OCD is believed to be simply a persistent skeletally immature lesion that has remained into adulthood. Several studies have shown poor results of treating AOCD without surgical intervention. In skeletally mature athletes with symptomatic yet stable OCD lesions, the senior author’s preferred treatment is operative, because these lesions have little capacity for healing with nonoperative treatment. However, using an unloader brace to minimize weight bearing through the involved compartment of the knee is an option that may allow the athlete to compete for the remainder of the season. Of course, the following return-to-play criteria must be met:

1.

Ability to meaningfully contribute to the team
2.

No catching (motion of knee is temporarily inhibited) or locking (motion of the knee is halted) sensations
3.

Full range of motion
4.

Normal strength
5.

No effusion or trace effusion

Surgical Management of OCD in the Athlete

Many options are available for the surgical treatment of OCD lesions. For unstable yet salvageable OCD lesions, the senior author’s preferred treatment is fixation with bone grafting ( Fig. 1 ). Through an arthrotomy, the OCD lesion is carefully prepared by removing sclerotic and necrotic bone as well as fibrous tissue interposed between the parent bone and progeny fragment. Autogenous cancellous bone is harvested from the ipsilateral proximal tibia from a region about 25 mm distal to the anteromedial joint line. The periphery of the parent bone is drilled with a 1.8-mm drill to facilitate the efflux of marrow elements to augment healing. In the setting of adequate bone on the progeny fragment, fixation is achieved with a variable-pitch metallic screw, which does not require subsequent removal. In the setting of inadequate bone on the progeny fragment (ie, fragmented bone or bone <3 mm thick), fixation is achieved with 1.5-mm solid screws, which do require removal about 8 weeks postoperatively.