Predictors for outlier results after radial head replacement for acute complex elbow instability.

Abstract

Radial head replacement (RHR) is a well-stablished treatment for comminuted fractures (RHF). In most cases it provides satisfactory long-term functional results. However, some patients have pain and significant functional limitations. Our aim was to identify patients who underwent a RHR for acute trauma and had a clinical outcome that was considered an outlier. We assessed specific factors that contributed to an unfavorable result. From a cohort of 134 patients undergoing RHR for acute complex elbow instability, the Oxford Elbow Score (OES) was used to identify patients whose score was below the p25 (<35 points). Thirty-five patients (23 women and 12 men) with a mean age of 48 years (18-78) and a mean follow-up of 77 months (24-192) were below the p25. The univariate analysis included preoperative demographic characteristics, implant design, diagnosis and postoperative clinical and radiographic outcomes. Results were compared to patients above the p75. An additional multivariate analysis was performed to identify predictive variables of a p25 OES. Patients belonging to p25 OES were significantly younger (48 vs 58 years, p=.02), had a higher energy trauma (p=.01) and their diagnosis was more commonly a terrible triad (18 vs 11, p=.004) or an Essex-Lopresti (5 vs 0) injury. Twenty-two patients received a smooth-stem RHR and 13 an anatomic design, with no correlation between implant design and p25 OES (p=.83). The p25 OES showed significantly lower flexion-extension (p=.01), pronation (p=.01), VAS satisfaction (p<.001), MEPS and DASH scores (p<.001), with more pain (p<.001). All patients who required implant removal belonged to the p25 OES (10 vs 0). On multivariate analysis, odds of belonging to p25 OES were greater only for younger (odds ratio [OR] = 0.94, 95% confidence interval [CI]: 0.88-0.99, p=.04), and female patients (OR = 20.29, 95% CI: 2.27-181.8, p=.007). A very strong correlation was observed for postoperative VAS for pain above 3 points, worse DASH and MEPS scores with a p25 OES. Lower flexion-extension arc of motion, lower levels of satisfaction, lateral ligament insufficency, the overall presence of complications and implant removal showed moderate correlation with p25 OES. RHR for traumatic complex elbow instability generally provides good long-term outcomes with few complications. Some preoperative characteristics such as younger age, high-injury trauma, terrible triad and longitudinal instability are related to a lower OES with worse overall clinical outcomes. Female sex and younger age may be predictors of an unsatisfactory outcome after a RHR.