Total elbow arthroplasty: Influence of implant positioning on functional outcomes.

BACKGROUND

Restoring the axis of rotation is often considered crucial to achieving good functional outcomes of total elbow arthroplasty. The objective of this work was to evaluate whether variations in implant positioning correlated with clinical outcomes.

HYPOTHESIS

Clinical outcomes are dictated by the quality of implant positioning.

MATERIAL AND METHODS

A retrospective review was conducted of data from 25 patients (26 elbows). Function was assessed using a pain score, the Disabilities of the Arm, Shoulder, and Hand (DASH) Score, and the Mayo Elbow Performance Score (MEPS). The patients also underwent a clinical evaluation for measurements of motion range and flexion/extension strength. Position of the humeral and ulnar implants was assessed by computed tomography with reconstruction using OsiriX software. Indices reflecting anterior offset, lateral offset, valgus, height, and rotation were computed by subtracting the ulnar value of each of these variables from the corresponding humeral value. These indices provided a quantitative assessment of whether position errors for the two components had additive effects or, on the contrary, counterbalanced each other. Elbows with prosthetic loosening or extensive epiphyseal destruction were excluded.

RESULTS

Of the 26 elbows, 5 were excluded. In the remaining 21 elbows, the discrepancy between the humeral and ulnar lateral offsets was significantly associated with pain intensity (P ≤ 0.05) and the MEPS (P ≤ 0.05). Anterior position of the ulna relative to the humerus was associated with decreased extension strength (P ≤ 0.05) and worse results for all functional parameters (P ≤ 0.05).

DISCUSSION

In the absence of loosening, positioning errors seem to adversely affect functional outcomes, probably by placing inappropriate stress on the soft tissues.

LEVEL OF EVIDENCE

III.