Introduction

Beyond common fractures and their attendant complications, elbow problems are relatively uncommon in the young. Nevertheless, there are a number of conditions that can result in elbow symptoms, especially in young athletes. Osteochondritis dissecans (OCD) is but one of these conditions. It is important to identify OCD promptly because the prognosis is often poor and appropriate management can prevent deterioration and improve the outcome.

Background/aetiology

Sporting activities that require the upper limb to repeatedly bear abnormal loads are most commonly responsible for elbow pain in the skeletally immature. Activities include gymnastics, weightlifting and, most frequently, baseball. Baseball pitching imparts repeated valgus stress to the elbow joint. This tensions the medial structures and compresses the lateral structures, leading to a variety of elbow symptoms which have been termed ‘little leaguer’s elbow’. Experience is greatest in the USA and Japan, where baseball is a popular youth sport, but relatively limited in the UK.

The most common ‘little leaguer elbow’ symptoms are on the medial side of the joint and are related to traction injury and inflammation of the medial collateral structures, especially the vulnerable medial epicondyle. Less frequently, symptoms are lateral and related to compressive overloading of the lateral bony structures, including the radial head and especially the capitellum. OCD and Panner’s disease are both seen in the capitellum and it is therefore important to define and distinguish these conditions (Table 14.1).

Table 14.1 Panner’s disease and osteochondritis dissecans

Panner’s disease is considered to be an avascular necrosis of the developing capitellar ossification centre. It is characterized initially by radiological sclerosis and then fragmentation of the capitellum (Fig. 14.1), followed by gradual restoration. It is not necessarily associated with trauma.^1,2 The process is very similar to the series of changes seen in the femoral epiphysis in Perthes’ disease. Panner’s disease occurs in the relatively young (under 10 years). Management is usually non-operative and primarily involves avoidance of the causative stress together with range-of-movement therapy to maintain extension. Although it may take some time for the radiological lesion to resolve, the prognosis is relatively good. As in Perthes’ disease, the capitellar cartilaginous anlagen, devoid of its supporting bony nucleus, can deform and sometimes reossifies into a flattened oval in the sagittal plane, ultimately limiting full extension.

Figure 14.1 Panner’s disease. Sclerosis and fragmentation of the entire ossific nucleus of the capitellum.

From J Bone Joint Surg Am, April 1960; 42:513–516. Avascular necrosis of the capitellum humeri (Panner’s disease): a report of a case. Charles J. Heller and Leon L. Wiltse.

By contrast, OCD occurs most commonly in the adolescent age range. It is usually a more discreet condition, affecting a section of the subchondral bone and the overlying articular cartilage (Fig. 14.2). The pathology and radiology are similar to OCD seen in other joints such as the knee and ankle and there is potential for loose body formation. Management is sometimes operative and depends on the stability of the OCD lesion. Prognosis is accordingly variable and generally worse than Panner’s disease. Early recognition is important because appropriate early management can influence the prognosis.

Figure 14.2 Radiographic classification of OCD. Grade I (A) is localized flattening or radiolucency. Grade II (B) is a non-displaced fragment. Grade III (C) is a displaced or detached fragment with an empty defect.

From J Bone Joint Surg Am, June 2007; 89:1205–1214. Classification, treatment, and outcome of osteochondritis dissecans of the humeral capitellum. Masatoshi Takahara, Nariyuki Mura, Junya Sasaki, Mikio Harada, and Toshihiko Ogino.

The capitellum of the immature elbow has a tenuous vascular supply consisting of one or two posterior vessels that traverse the capitellar cartilage before entering the epiphysis. There is no metaphyseal blood supply until the physis closes at maturity.³ This tenuous circulation makes the capitellum vulnerable to avascular necrosis following lateral condyle fractures and it is postulated that it may also play a role in the genesis of Panner’s disease and OCD. Some reports suggest a genetic predisposition in some families but most evidence supports the hypothesis of repeated shear and compressive trauma, particularly in relation to OCD.

Presentation

Although the articular surface of any joint can be affected by OCD, there is a predilection for the convex surfaces of load-bearing joints, especially the knee and ankle. At the elbow any surface can be affected but the anterolateral convex surface of the capitellum is most frequently involved when the upper limb is subjected to supra-physiological load-bearing activities.

The patient usually presents with focal pain on the lateral side of the elbow. There is often a history of athletic activity. The condition most frequently affects male throwing athletes and female gymnasts. The dominant (throwing) elbow is predominantly affected. Symptoms are usually worse with activity and improve with rest, although there can be a prolonged ache following activity. There may be mechanical symptoms such as clicking or locking, especially if the lesion is unstable or if loose bodies are present. Clinical examination identifies tenderness over the capitellum. Full extension is often limited. Pain can be provoked by valgus stress of the elbow or by active pronation and supination of the extended elbow, which generates dynamic compression of the lateral structures.

Investigation and classification

Evaluation should not overlook other potential explanations for pain. Investigation usually commences with standard anteroposterior and lateral plain radiography. The typical early appearance of OCD is anterolateral radiolucency within the capitellum, with flattening progressing to irregularity of the central or anterolateral articular surface. A separated fragment can subsequently form and either remain in its bed or become detached, forming a loose body. Radiographic findings can be classified into three grades (Fig. 14.2).⁴ Grade I is localized flattening or radiolucency. Grade II is an undisplaced fragment and grade III a displaced or detached fragment. Reliable grading is, however, difficult and subject to inter-observer variation.

Furthermore, plain radiography lacks sensitivity. Early grade I changes are difficult to visualize and early lesions can be easily overlooked. One study has shown that only 7 of 15 known cases of early OCD were identified with plain radiographs.⁵ As a result, some authors recommend supplementing the standard films with an anteroposterior view of the elbow when it is flexed to 45° to give a tangential view of the anterolateral capitellum, where the lesion is most typically located.⁶ Magnetic resonance imaging (MRI) is more sensitive than plain radiography and should therefore be utilized if the history and examination suggest OCD as a possible differential diagnosis.

The primary purpose of investigation is to both identify and classify the extent of the lesion. However, before discussing the relative merits of MRI it is worthwhile reviewing the current arthroscopic classification of OCD.

Classification of the lesion is critical because current management guidelines are dependent on the type of lesion present and particularly on its stability. In an effort to standardize the classification of OCD lesions, the International Cartilage Repair Society (ICRS) has published a system for clinical cartilage evaluation and imaging assessment (Table 14.2).⁷ Prognosis deteriorates from OCD I to OCD IV. Determining the stability of the lesion is the critical issue. More stable lesions have a better prognosis and can sometimes heal completely with non-operative treatment. Unstable lesions have little or no chance of healing with non-operative management and require surgical treatment.

Table 14.2 ICRS classification of OCD

From Brittberg M, Winalski CS. Evaluation of cartilage injuries and repair. J Bone Joint Surg Am April 2003; 85:58–69.

By comparison with plain radiography MRI is sensitive and can accurately define the site and extent of OCD lesions. MRI assessment of stability is, however, more difficult and controversial. Some authors have suggested that unstable lesions are surrounded by a rim of high signal intensity or a fluid-filled cyst on T2-weighted images.⁵ Other studies have demonstrated that such high signal deep to the OCD fragment merely represents granulation tissue and the determination of instability can only be certain if a break in the articular surface is also demonstrated.⁸ MR arthrography, which can identify an articular surface breach more precisely, is therefore sometimes used to improve the accuracy of MR assessment.⁹ There is also emerging evidence that ultrasonography is a potentially useful imaging modality to evaluate OCD lesions and their stability, but interpretation requires considerable operator experience.¹⁰ Currently therefore surgical visualization and probing of the lesion, either by arthroscopy or arthrotomy, remains the gold standard for the assessment of OCD lesions.

Outcome and literature review

The long-term prognosis of advanced OCD of the capitellum is poor. Follow-up studies suggest that approximately half of all patients have long-term symptoms of pain during activities of daily living, restricted range of motion and radiological signs of degenerative change.^11–13 On the other hand, there is evidence that appropriate management of early disease can prevent deterioration and result in an improved outcome.⁶

Stability and viability of the OCD lesion as well as the presence or absence of an open capitellar physis are key factors in predicting prognosis. In the most comprehensive review of the condition to date Takahara et al⁴ defined a stable lesion as one that could heal completely with non-operative elbow rest, and an unstable lesion as one that would have significantly better results if managed surgically. Observations were made regarding the determination of whether a lesion was likely to be stable or unstable (Table 14.3). Based on this study, at the time of initial presentation patients likely to have stable lesions have an open physis as well as an almost normal range of elbow motion and only early radiological flattening or radiolucency (radiological grade I). Conversely, patients likely to have an unstable lesion have a closed growth plate or a restriction of elbow motion ≥20° or radiological fragmentation (radiological grade II or III).

Table 14.3 Radiographic and clinical characteristics of stable and unstable OCD lesions

Lesions that are likely to be stable have all of the characteristics in the left-hand column at the time of initial presentation. Just one of the characteristics in the right-hand column at the time of initial presentation suggests that the lesion is likely to be unstable.

From Takahara, Nariyuki Mura, Junya Sasaki, Mikio Harada, and Toshihiko Ogino. Classification, treatment, and outcome of osteochondritis dissecans of the humeral capitellum. Masatoshi J. Bone Joint Surg Am June 2007; 89:1205–1214.

By this classification more than 90% of patients in Takahara et al’s study⁴ had unstable lesions. Stable lesions were relatively rare, representing less than10% of patients. Although relatively uncommon, patients with stable lesions have a good prognosis provided they follow medical advice to rest and avoid repetitive injury. Evidence suggests that failure to adhere to such recommendations leads to progression and deterioration.^4,6

An open physis is an indicator of a good prognosis but does not guarantee a good outcome. Even when the physis was open, Takahara et al⁴ showed that two out of three radiological grade II lesions failed to heal completely. Radiological grade II lesions were therefore considered to represent partially unstable lesions, and surgical treatment, irrespective of an open physis, was recommended. Similarly, loss of range of motion equal to or greater than 20°, in spite of an open physis, was also considered to represent instability because three out of four such patients failed to respond to non-operative management and were eventually found to have unstable lesions at operation. Conversely, a closed physis is an indicator of poor prognosis. Takahara et al⁴ showed that in the presence of a closed physis all OCD lesions failed to heal following non-operative treatment. All lesions that were treated operatively when the physis was closed were found to be unstable at surgery and the results of surgery were significantly better than after non-operative treatment.

A practical management approach

Persistent symptoms suggestive of OCD require investigation. If plain radiographs do not demonstrate a diagnosis, MRI should be used to determine whether OCD is present.

Once a lesion is identified management is directed by the determination of stability. Takahara et al’s criteria (Table 14.3)⁴ can be used in combination with MRI. The determination of stability using MRI is controversial but can be enhanced with MRI arthrography. Contrast tracking into the interface between the fragment and the proximal bone suggests a break in the articular cartilage and instability.

Conclusions

Given the potential morbidity of OCD of the capitellum, awareness of the condition among medical practitioners, parents and the coaches of children and adolescents participating in provocative sporting disciplines is critical for appropriate management and prevention. In the interests of prevention of this condition, the American Academy of Orthopaedic Surgeons (AAOS)²⁵ has offered guidance to little league baseball coaches and players. The AAOS recommends that pitchers should play no more than three to four innings each game and limit pitches to no more than 200 in each week. This includes both practice and competitive play.

If, in spite of preventative measures, elbow symptoms commence in a young athlete, then the offending activity should be discontinued until symptoms have stopped. If symptoms persist in spite of rest or if they return when activity recommences, there should be a low threshold for medical referral. There is now good evidence that identification and appropriate management of early disease can prevent deterioration and will result in a better, sometimes normal, outcome. Persistent disregard of symptoms can lead to advanced disease where the long-term prognosis must remain guarded.