Osteolysis and outcome after total elbow arthroplasty: impact of proximal ulna dorsal angulation and radiocapitellar ratio.

BACKGROUND

Osteolysis after total elbow arthroplasty (TEA) remains a major concern, with an average 13%-15% loosening rate at 7 years. Two new radiological parameters of elbow anatomy could play a role in this complication: the posterior ulnar dorsal angulation (PUDA) and the radiocapitellar ratio (RCR). The primary objective of this study was to evaluate the association between PUDA and RCR on loosening after TEA.

METHODS

This retrospective single-center study included all patients who underwent TEA from 1996 to 2021 with a minimum follow-up of 2 years. Patient evaluation included range of motion and function (Quick-Disabilities of the Arm, Shoulder and Hand, patient-rated elbow evaluation, and Mayo Elbow Performance Score [MEPS]). To assess implant position and limb length discrepancy, new bilateral upper limb radiographs were taken. Lateral elbow radiographs were taken to measure PUDA and RCR on the TEA side and native side. PUDA was considered high when >7°, and RCR was abnormal when <-5% or >13%. Radiographs were analyzed by an independent evaluator to assess loosening.

RESULTS

Thirty-four TEAs from 30 patients available for assessment were included. The mean age was 64 years (range 42-86), and 90% (n = 27) were females. TEA was performed following trauma in 13 patients and secondary to degenerative conditions in 17 patients. The mean follow-up was 7.4 years. The mean PUDA and RCR were 6.7 and -1.2%, respectively. PUDA was high in 33% of patients, and RCR was abnormal in 53%. The MEPS score was significantly better in patients with a lower PUDA compared to those with a higher PUDA, 87 (±13) and 73 (±17), P = .038, respectively. A higher PUDA was not associated with humeral or ulnar component loosening (Humeral component: 40% vs. 9% loosening, P = .053; Ulnar component: 20% vs. 5% loosening, P = .251). Functional scores and loosening rates were not impacted by differences in RCR.

CONCLUSIONS

PUDA had an impact on functional scores, with significantly better MEPS in patients with lower PUDA. PUDA was not statistically related to loosening of the humeral or ulnar components. RCR had no impact on loosening and outcomes after TEA in our study.