Arthroscopic Management of Osteochondritis Dissecans of the Capitellum

Introduction

Franz Konig first described osteochondritis dissecans (OCD) lesions in 1887 as an inflammatory response that resulted in the formation of intraarticular loose bodies. We have since learned that OCD lesions do not contain inflammatory cells, but they are responsible for loose body formation. The current characterization of OCD lesions encompasses the noninflammatory, progressive separation of a discrete area of articular cartilage from underlying subchondral bone.

OCD lesions most commonly occur in the knee, ankle, and elbow. Although authors have reported lesions occurring at the radial head, olecranon, olecranon fossa, and trochlea, the capitellum is the most common site of OCD lesions in the elbow. OCD lesions in the elbow typically occur on the central or anterior lateral portion of the capitellum. These lesions afflict athletes between the ages of 11 and 21 years old who are involved in sports that can result in overuse of the elbow, such as baseball, gymnastics, weightlifting, racquet sports, and cheerleading. OCD lesions are more prevalent in males than females. The dominant arm is almost always affected, but OCD lesions occur bilaterally in 5% to 20% of patients.

Natural History

Even though our understanding of the details of the natural history of elbow OCD lesions is limited, we do know that early intervention is instrumental in preventing long-term disability. Early diagnosis and proper treatment allow the lesion to heal without long-term consequences. Mihara et al. observed that 88% of elbows with early signs of an OCD lesion went on to heal without complications when they had patients cease the offending activity completely at the time of diagnosis. Early signs on radiograph include radiolucency and capitellar flattening. Rest simply eliminates the offending agent—repetitive compressive forces at the radiocapitellar joint.

Patients, however, often initially present with advanced OCD lesions. Advanced lesions can potentially end a playing career and result in long-term arthritis. At a 23-year follow up, Bauer et al. reported that 50% of their patients had impaired motion and pain with activity. Takahara et al. also demonstrated that at an average follow-up of 12.6 years, 50% of patients with advanced capitellar OCD lesions at the time of diagnosis progressed to residual symptoms that interfered with their activities of daily living. OCD lesions of the capitellum are not a self-limiting condition and, if not treated properly, result in long-term elbow pain and disability.

Pathophysiology

Histopathology

Early lesions initially exhibit hyperemia and edema in the subchondral bone. The overlying articular cartilage is damaged, and the deep articular cartilage layer separates from the subchondral bone. Vascular granulation tissue grows into the space of the necrotic subchondral bone. The overlying articular segment undergoes one of two fates. If the articular segment remains attached to the subchondral bone, then new bone will replace the absorbed, necrotic bone and the lesion will heal. If, however, the articular segment is violated during this process (e.g., continued repetitive trauma) or lacks sufficient support, then the articular segment, along with necrotic subchondral bone, will detach and form a loose body. Thus, early diagnosis and rest are critical so that the cartilage cap is not violated and can heal. Lesions that do not heal undergo significant degeneration of the articular cartilage that resembles osteoarthritis.

Presentation

Patients most commonly complain of pain and decreased range of motion in the elbow. The pain is insidious in onset, progressive, and relieved by rest. The pain may be localized over the lateral elbow, but patients often present with generalized elbow pain. Patients report elbow stiffness that manifests as a loss of terminal extension, instead of flexion. Patients may describe mechanical symptoms, such as popping, clicking, or catching. Loose bodies or an inflamed posterior lateral plica commonly causes these mechanical symptoms.

Physical Exam

Patients with capitellar OCD lesions will occasionally have an effusion. Patients can demonstrate a flexion contracture where both active and passive ranges of motion are decreased with a 5- to 20-degree loss of terminal extension. Crepitus may also be present during range of motion testing. The most reliable provocative maneuver is the radiocapitellar compression test, first described by Baumgarten et al. The examiner pronates and supinates the forearm with the elbow extended, which generates pain in the lateral compartment of the elbow by compressing the radiocapitellar joint. If patients have a painful posterior lateral plica, then pronating the forearm with the elbow at more than 90 degrees of flexion will produce a snapping.