gms | German Medical Science

Objectives/Interrogation: Overlengthening of a radial head implant has been associated with less than optimal clinical outcomes and capitellar erosions. The purpose of this study was to identify which factors, both clinical and radiological, have influenced the clinical results in our series.

Methods: We analysed the relation of the initial injury, the repairs associated to implant insertion and the implant length with clinical outcomes. Two postop radiological measurements were made by two independent investigators: the distance between the proximal edge of the lesser sigmoid notch and the proximal implant edge, and the lateral ulnohumeral joint opening angle. Mean values of both measurements were taken as reference. Clinical outcomes were assessed with range of movement measurements, the Mayo Elbow Performance Score (MEPS) and the DASH. In addition to univariable descriptive analysis, comparisons of means and correlations were made using nonparametric tests.

Results and Conclusions: During the 2005-2017 period, we performed 49 radio head arthroplasties (MoPyC, Bioprofile, Tornier). 31 patients (21 women and 10 men, average 53 years) agreed to be evaluated. Mean follow-up was 5 years. The initial lesion was a Masson type III fracture in 5 cases, type IV in 6, a triad in 12, and an association with other proximal ulnar fractures in the remaining 8. The treatment in 9 cases was just radial head arthroplasty, while in 10 it was associated with coronoid fixation and ligamentous repair. The rest of the cases received different combinations of treatment. Implant length was aligned with the proximal margin of the lesser sigmoid notch in 16 cases, was higher in 12 (mean 3 mm, SD 1.5) and inferior in 3 (mean 3.4 mm, SD 1.7). The lateral ulnohumeral joint opening angle was 10.7º (SD 2.6º). Although the best clinical results in mobility, MEPS and DASH have been obtained in Masson fractures type III and IV, the differences have not been significant, nor have there been differences according to the treatment used. Significant correlations (p <0.05) were observed between the increase in the ulnohumeral angle and the decrease in flexion and supination mobility. Variations in implant lenght in our series have shown no relation to the clinical outcome.

An overlengthening or shortening up to 3 mm has not shown to alter the clinical results in our series, while an excessive lateral ulnohumeral joint opening has a negative effect on mobility.