Six patients who had undergone radial head excision for radial head fractures were enrolled after retrospective identification. We created 3-dimensional bone models using computed tomography data obtained from the injured and uninjured elbows. Humerus and ulna models were divided into the anatomical regions and the bone density of each region was assessed and described by their percentage of high-density volume (%HDV). We also constructed finite element models and measured the stress values at each region. Furthermore, we compared the bone morphology by superimposing the operative elbows onto mirror-image of the non-operative elbows.
The mean interval from radial head excision to examination was 8.4 ± 3.3 years. The %HDV of the operative side were higher than those of non-operative side at the anterolateral trochlea (77.5 ± 6.5% vs. 64.6 ± 4.0%; p = 0.028) and posterolateral trochlea (70.7 ± 7.8% vs. 63.1 ± 3.8%; p = 0.034) regions of the distal humerus. Reciprocal changes were observed in the proximal ulna, as %HDV was also higher in the lateral coronoid (52.6 ± 9.6% vs. 34.2 ± 6.6%; p = 0.007). The stress distributions paralleled bone density measurements. The operative elbows demonstrated an enlarged capitellum and a widened and deepened trochlea with osteophyte formation, compared with non-operative side.
In elbows treated with radial head excision, we identified asymmetric bone density and stress alterations at the lateral side of the ulnohumeral joint and bone morphologic changes across the joint. These data support the theory that radial head excision contributes to ulnohumeral arthritis over the long-term.
Level III; Case-Control Design; Prognosis Study.
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