Prosthetic Resurfacing of Engaging Posterior Capitellar Defects in Recurrent Posterolateral Rotatory Instability of the Elbow

Objective:
Posterolateral rotatory instability (PLRI) is a common mechanism of recurrent elbow instability. While the essential lesion is in the lateral ulnar collateral ligament (LUCL), it may be associated with concomitant bony lesions in the coronoid process, the posterior capitellum and the radial head, reducing the articular surface restraint against joint dislocation. Currently, there is no proven treatment option for recurrent PLRI associated with posterior capitellar deficiency.

Methods:
A case series of 5 patients with recurrent PLRI of the elbow, associated with a posterior capitellar impaction fracture engaging with the radial head during normal range of motion. The patients were treated surgically by LCL reconstruction or repair and off-label reconstruction of the capitellar joint surface using a small metal prosthesis designed for metatarsal head resurfacing (Arthrosurface HemiCAP toe classic).

Results:
5 patients (3 adolescent males, 2 adult females) were treated between 2007 – 2018. At a mean follow up of 4.5 years, all patients had complete relief of their symptomatic instability. The posterolateral rotatory drawer test was negative in four patients and equivocal in one. None had pain at rest, and 2 patients had mild pain (VAS 1-3) during physical activity. According to the SOD score, 3 rated their elbow as normal, 1 as almost normal, 1 as greatly improved, and the average score was 9.4. On radiographic follow up there were no signs of implant loosening. None of the patients required re-intervention.

Conclusion:
Recurrent PLRI of the elbow associated with an engaging posterior capitellar lesion can be treated successfully by LCL reconstruction/repair and filling the capitellar defect with a metal prosthesis, with excellent clinical results in the short-medium term.