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A 23-year-old woman who had an episode of elbow injury which was treated cast immobilisation in childhood with residual cubitus varus sustained a posterior fracture dislocation of the same elbow. She was treated with closed reduction. Six months later, however, her elbow became stiff, and a persistent posterolateral rotatory subluxation was noted. Operations were performed in two steps; first, the radial head, which was subluxed posteriorly, was reduced and the lateral collateral ligament complex was reconstructed, and second, the stiff elbow was mobilised. Two years after the first surgery, the function of the elbow was satisfactorily recovered.

We have retrospectively reviewed the clinical, preoperative ultrasonographic, and operative findings of eight patients who had tardy ulnar nerve palsy caused by a cubitus varus deformity. The mean varus angle on the affected side was 23°. With preoperative ultrasonography, the anterior dislocation of the ulnar nerve from the medial epicondyle was detected in dynamic scanning of short-axis images, and long-axis images revealed nerve compression and kinking in the proximal border of the flexor carpi ulnaris. Operative findings revealed compression of the ulnar nerve by a fibrous band, which was released in all cases. The cause of the tardy ulnar nerve palsy in this series of patients was constriction by a fibrous band and kinking in the proximal border of the flexor carpi ulnaris due to ulnar nerve dislocation from compression resulting from the forward movement of the medial head of the triceps brachii muscle.

Background: We identified a subset of patients who had posterolateral rotatory instability (PLRI) following corrective osteotomy for asymptomatic cubitus varus deformity. We aimed to identify risk factors for PLRI in such patients by comparing this subgroup to patients who did not demonstrate PLRI following osteotomy.

Methods: We retrospectively reviewed the medical records and radiographs of 22 patients with cubitus varus that underwent corrective osteotomy at our institution between 2003 and 2010. All patients underwent surgery for cosmetic reasons, and no patient reported functional problems such as PLRI or ulnar nerve symptoms pre-operatively. We sought to identify differences between those that experienced an increase in PLRI after osteotomy (PLRI group) and those that did not (non-PLRI group) with regard to demographics, degree of deformity, amount of surgical correction, and final outcomes.

Results: Five patients had PLRI after osteotomy, and all five subsequently underwent lateral ulnar collateral ligament reconstruction using a triceps tendon graft. No statistically significant difference was observed between the PLRI and non-PLRI groups in terms of demographics, degree of deformity, amount of surgical correction, range of motion, and final Mayo Elbow Performance Index (MEPI) and the Disabilities of Arm, Shoulder, and Hand (DASH) scores. However, the PLRI group had marginally greater medial displacement of the distal fragment.

Conclusions: This study demonstrates that PLRI can become apparent after corrective osteotomy for cubitus varus in the absence of clinical symptoms of instability preoperatively. We suggest that careful examination for PLRI should be performed after surgical correction for cubitus varus deformity, and surgeons should be prepared to proceed with simultaneous reconstruction of the lateral ligaments of the elbow.