Session VIII - Pediatrics/Spine

Posterolateral Rotatory Instability of the Elbow following Varus Malunion of Pediatric Supracondylar Humeral Fracture

Michael D. McKee, MD, FRCS(C), St. Michael's Hospital and the University of Toronto, Toronto, Canada; Shawn W. O'Driscoll, MD, PhD; Bernard F. Morrey, MD; Robert J. Spinner MD, Mayo Clinic, Rochester, MN; W. Ben Kibler, MD, Lexington, KY

Purpose: The purpose of this multi-center study was to document a series of 21 cases of delayed-onset recurrent posterolateral rotatory instability (PLRI) of the elbow secondary to varus malunion of a pediatric supracondylar humeral fracture.

Introduction: Traditional teaching suggests that the varus/extension deformity that can result from the malunion of a pediatric supracondylar humeral fracture is essentially a cosmetic deformity with little functional significance. As such, operative intervention is discouraged.

Methods: After recognizing PLRI in a patient with elbow pain and instability following a longstanding distal humeral varus malunion, the authors have identified this condition in 21 patients. All patients presented with lateral elbow pain and tenderness, cubitus varus, a sense of instability, and a positive posterolateral elbow apprehension test. Stress radiographs and/or examination under anesthesia confirmed the diagnosis in all patients. All of the patients, whose mean age was 33 years, had suffered a supracondylar humeral fracture as a child. Most had what would be considered by modern standards to be inadequate initial treatment of their fracture. The mean degree of cubitus varus was 15°.

Results: Operative treatment consisted of corrective osteotomy in 3 patients, reconstruction of the lateral ligamentous complex in 10 and both procedures in 8. At a minimum of one-year follow-up, only 2 patients had recurrence of their symptomatology: the remainder had excellent relief of pain and restoration of elbow stability.

Discussion: We postulate that the varus distal humeral malunion displaces the mechanical axis of the triceps medially, resulting in eccentric loading of the elbow and excessive torque laterally with movement or stress. This results in chronic stretching of the lateral ligamentous structures and in time produces overt clinical symptomatology. Longstanding varus malunion of the distal humerus is a previously unrecognized cause of PLRI. Recognition of this condition as a cause of chronic elbow pain in the predisposed individual is key.

Conclusion: PLRI is a late complication of varus malunion of pediatric supracondylar fractures. Surgical treatment is effective in restoring stability to the elbow, decreasing pain and improving function.

Significance: PLRI has not been previously reported following varus malunion of pediatric supracondylar fractures. Cubitus varus malunion is not an isolated cosmetic deformity and can lead to elbow instability and pain in adults. If recognized, this complication is amenable to surgical correction through supracondylar osteotomy and/or ligament reconstruction. We postulate that abnormal elbow mechanics play a significant role in the development of this condition.