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Symptomatic osteochondritis dissecans lesions of the knee frequently occur in skeletally immature patients. When conservative treatment fails, retro-articular drilling, also known as intraepiphyseal extra-articular drilling, becomes a viable treatment option. The purpose of this article is to describe our surgical technique and postoperative management of patients with stable osteochondritis dissecans lesions involving the femoral condyles. This technique is reproducible, uses readily available equipment, and has yielded good clinical outcomes with high healing rates and relatively early return to sports.
See video under supplementary data.
Osteochondritis dissecans (OCD) lesions of the knee can be either silent or symptomatic and are believed to occur with an incidence of 15 to 30 persons per 100,000.
Treatment of OCD lesions is controversial and varies based on patient age, skeletal maturity, and lesion location, size, and stability. Historically, stable lesions have been treated nonoperatively with activity modification and occasional bracing or immobilization. When conservative treatment fails or when there is evidence of lesion instability, surgery may become indicated. The American Academy of Orthopaedic Surgeons Task Force on Osteochondritis Dissecans has recently critically reviewed the existing literature and developed guidelines to assist practitioners in the management of OCD lesions.
Their results were largely inconclusive, showing the significant weaknesses in the literature on this topic. To date, no optimal surgical treatment has been identified or agreed upon. At our institution, we prefer to use a retro-articular drilling technique, also known as intraepiphyseal extra-articular drilling, for stable OCD lesions. The rationale for this approach is that this technique avoids damage to the articular cartilage and physis. In addition, it requires minimal equipment that is readily available in the operating room (Fig 1), and it has documented good clinical outcomes.
The purpose of this article is to present our technique of retro-articular drilling for stable OCD lesions of the femoral condyle in skeletally immature patients.
An example of the surgical technique can be seen in Video 1. Initial radiographs including anteroposterior, lateral, merchant, and Rosenberg (tunnel) views are obtained in all patients to assess the lesion size and location (Fig 2). Because of the high incidence of contralateral disease, we routinely obtain images of the opposite knee. A magnetic resonance imaging study is then obtained to help assess the stability of the lesion (Fig 3). In skeletally immature patients with no obvious radiographic instability of the lesion, a 3- to 6-month period of nonoperative care is instituted. During this time, all sporting activities are ceased, but the patients do not routinely use casts, crutches, or unloader braces. Patients with continuation of symptoms or those with no radiographic evidence of healing are then offered retro-articular drilling. Patients with more advanced disease including evidence of lesion instability or those who are skeletally mature are treated more aggressively with surgery in lieu of a trial of nonoperative care. In these patients, if the cartilage is intact at the time of the diagnostic arthroscopy, the lesion is drilled by the same technique.
With the patient supine on a radiolucent table, a diagnostic arthroscopy is performed. The articular cartilage is carefully visualized and probed to ensure no cartilage lesions or flaps are present. The OCD lesion is then graded according to the classification of Guhl
: grade 1, intact lesions; grade 2, lesions with early separations; grade 3, partially detached lesions; or grade 4, craters with loose bodies. All grade 1 and 2 lesions are treated with retro-articular drilling.
The arthroscopy equipment is then removed from the joint, and the knee is flexed 30° to 60° and is maintained in this position with a sandbag and thigh post (Fig 4). The degree of knee flexion is adjusted based on how posterior the lesion is on the femoral condyle and to optimize the appearance of the sclerotic rim of the lesion. The key is to be able to efficiently move between the modified Rosenberg and lateral radiographic projections without having to move the knee joint. The relevant bony anatomy is marked, and fluoroscopy is used to identify the location of the OCD lesion as well as the growth plate if it is still open. A 0.062-inch Kirschner wire is then advanced percutaneously to the center of the OCD lesion, starting in the epiphysis distal to the growth plate (Fig 5). As the Kirschner wire is advanced, resistance will be appreciated when the wire contacts the sclerotic rim of the lesion. A second region of resistance will then be appreciated, which represents the subchondral bone. When the first Kirschner wire has been advanced to the center-center position of the OCD lesion just through the subchondral bone, but not through the articular cartilage, the Kirschner wire is cut 5 cm from the skin. It is imperative to confirm the location of the Kirschner wire on both radiographic projections to confirm that it does not penetrate the articular cartilage. This wire then serves as a guide for all subsequent drillings. Ten to twenty additional drillings are performed circumferentially around the first guidewire in 3- to 5-mm increments depending on the lesion size. These additional drillings can be performed with a parallel wire guide (Synthes, Paoli, PA) or with a freehand technique (Fig 6). The arthroscope is then placed back in the knee to confirm that the articular surface has not been breached and that there are no unstable cartilage flaps.
Postoperatively, the patient is kept touch-down weight bearing or non–weight bearing for 6 weeks, but immediate range of motion is allowed. Weight bearing is then advanced, but activities are still limited until 3 months postoperatively. Radiographs and symptoms are assessed at 6-week intervals. Patients are allowed to advance their activities when they are pain free with any radiographic evidence of healing (Fig 7). If no evidence of healing is observed by 6 months, a repeat magnetic resonance imaging study is obtained. In these recalcitrant cases, a repeat drilling is considered if no evidence of healing is seen on the magnetic resonance images.
Our understanding and treatment approach for osteochondritis of the knee have evolved since König
first coined the term in 1887. Although nonoperative management remains the initial treatment of choice for stable lesions, operative procedures may be necessary when lesions fail to heal. A multitude of surgical approaches have been proposed for these lesions, including drilling (both retro-articular and transarticular), bone grafting, internal fixation, alignment procedures, and debridement. Because no randomized studies have been performed comparing these different approaches, there is no consensus as to optimal treatment. In our practice we prefer to use a retro-articular drilling technique. The primary advantages of this procedure are its technical ease, its cost-effectiveness, and its minimal equipment needs. Compared with transarticular drilling, the articular cartilage is not violated with a retro-articular drilling technique. In addition, posterior condylar lesions are more accessible with a retro-articular technique. The primary limitation of this technique is the requirement for fluoroscopy and its associated radiation. In general, however, we have found that minimal fluoroscopy shots are required once the surgeon becomes comfortable with this technique.
Results in the literature using this retro-articular technique have been promising. Edmonds et al.
reported on 59 children treated over an 8-year period in whom 75% of lesions were completely healed radiographically at 12 months and 98% were healed at 36 months. The average time to return to sports was 3 months. In their cohort 7 patients required additional procedures, which primarily consisted of repeat retro-articular drillings. Boughanem et al.
have reported similar findings with good clinical outcomes and lesion healing with a mean follow-up of 4 years and 2.5 years, respectively.
Retro-articular drilling is a safe, technically easy, and efficacious treatment for stable OCD lesions of the knee. Given its proven clinical outcomes, it is our preferred first-line treatment for stable lesions that have failed a course of nonoperative care.
This 4-minute, 20-second video walks you through the steps to complete retro-articular drilling for OCD of the right knee including patient positioning, necessary intraoperative tools, and surgical technique.
Osteochondritis dissecans of the distal femur and patella.