Osteochondritis dissecans of the elbow

Alterations in stress distribution patterns through the forearm joint surface of the elbow in baseball players assessed using computed tomography osteoabsorptiometry

BACKGROUND

The distribution of subchondral bone density well reflects long-term resultant stress acting on an articular surface in living joints. Consequently, a measurement of the distribution pattern can determine the stress distribution across the elbow joint surface under long-term loading conditions of baseball pitching. Our purpose was to elucidate the characteristic alterations in the distribution pattern of subchondral bone density across the forearm bones of the elbow with pitching activities. The hypothesis is that pitching activities would change the stress distribution in living subjects.

METHODS

The analysis was performed using computed tomography (CT) images obtained from the dominant elbow of ten nonthrowing athletes (control group), ten college baseball fielders (fielder group), and ten college baseball pitchers (pitcher group). The distribution pattern of subchondral bone density through the articular surface of the proximal radius and ulna bones was assessed using CT osteoabsorptiometry.

RESULTS

The maximum density area was located in the posterior part of the trochlea notch in all study participants. This maximum density area was significantly increased in the baseball groups compared with that in the control group. The pitcher group also showed a significant distribution of the maximum density area in the anterior part of the radial head.

CONCLUSION

Our analysis indicates that pitching activities increase actual stress on the articular surface not only in the posterior part of the trochlea notch but also in the anterior part of the radial head. The stress across the elbow may be expanded from the ulnohumeral to the radiohumeral joint by repetitive pitching activities in living subjects.

A retrospective evaluation of magnetic resonance imaging effectiveness on capitellar osteochondritis dissecans among overhead athletes

BACKGROUND

Magnetic resonance imaging (MRI) has been widely used to characterize osteochondritis dissecans (OCD) lesions. However, the usefulness of MRI for predicting fragment stability in OCD of the humeral capitellum (capitellar OCD) remains unclear.

HYPOTHESIS

Preoperative MRI cannot accurately diagnose fragment instability of capitellar OCD in overhead athletes.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 1.

METHODS

Twenty-seven male overhead athletes who had undergone surgery for capitellar OCD were included in the study. A single senior musculoskeletal radiologist blindly reviewed preoperative MRI of these OCD lesions. The radiologist reported the presence or absence of each of the 4 MRI signs indicating fragment instability as described by De Smet et al. The lesions were also classified according to the MRI staging system of Dipaola et al for characterizing the lesions. Intraoperative assessment of fragment stability was used as the gold standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined for fragment instability as assessed by MRI.

RESULTS

According to the MRI criteria by De Smet et al and the Dipaola et al staging system, 21 (78%) and 20 (74%) lesions were defined as unstable, respectively. The obtained results yielded a sensitivity of 89% and a specificity of 44% for diagnosing fragment instability using the De Smet et al MRI criteria and a sensitivity of 83% and a specificity of 44% using the Dipaola et al MRI staging system. The PPV and NPV for fragment instability were 76% and 67% using the De Smet et al criteria and 75% and 57% according to the Dipaola et al staging system, respectively. The overall correlation rate of Dipaola et al MRI and intraoperative stages was 41%.

CONCLUSION

Preoperative MRI cannot precisely diagnose fragment instability of capitellar OCD that requires operative treatments in overhead athletes. Especially, MRI indicating stable lesions is considered not to be useful in predicting intraoperative instability of capitellar OCD in this study population.

Long-term stress distribution patterns across the elbow joint in baseball players assessed by computed tomography osteoabsorptiometry

BACKGROUND

The distribution pattern of subchondral bone density is considered to highly reflect the stress distribution across a joint under long-term physiologic loading conditions. Therefore, the biomechanical characteristics over the elbow joint surface under long-term loading conditions of baseball pitching can be determined by a measurement of the distribution pattern.

HYPOTHESIS

Stress distribution over the elbow joint surface alters with long-term pitching activities.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Computed tomography (CT) imaging data from the dominant elbow of 10 nonthrowing athletes, 10 college baseball fielders, and 10 college baseball pitchers were collected for the current analysis. The distribution of subchondral bone density through the distal articular surface of the humerus was measured using a CT osteoabsorptiometry method. The quantitative analysis of the obtained data focused on location and size of the maximum density area at the articular surface.

RESULTS

The maximum density area of subchondral bone across the articular surface of the distal humerus was located in the posterior part of the trochlea in all subjects. This maximum density area was significantly increased in the pitcher group, compared with that in other groups. Additionally, the pitcher group demonstrated a significant distribution of the maximum density area in the anterior part of the capitellum.

CONCLUSION

The results indicate that actual stress across the elbow is concentrated in the posterior part of the trochlea in humans. Baseball pitching may produce excessive or repetitive stress against not only this part, but also the anterior part of the capitellum. The majority of osteochondritis dissecans lesions affecting the elbow are found in the anterior part of the capitellum in throwing athletes. The results may support an important role of mechanical conditions in the cause of elbow osteochondritis dissecans.