Proximal tibial opening wedge osteotomy as the initial treatment for chronic posterolateral corner deficiency in the varus knee: a prospective clinical study.

BACKGROUND Nonoperative treatment of posterolateral knee injuries tends to yield poor results. In patients with chronic posterolateral knee injuries, failure to correct genu varus alignment will often result in failure of the posterolateral knee repair or reconstruction. PURPOSE To prospectively assess the functional outcomes of patients with combined grade 3 posterolateral instability and genu varus alignment initially treated with a proximal tibial opening wedge osteotomy. STUDY DESIGN Cohort study (prognosis); Level of evidence, 2. METHODS Twenty-one patients with combined chronic posterolateral corner deficiency and genu varus alignment were initially treated with a proximal tibial opening wedge osteotomy and observed prospectively. Second-stage ligamentous reconstruction was performed in patients with continued clinical and functional instability after the osteotomies had healed and they had undergone at least 3 months of rehabilitation. RESULTS At a mean follow-up of 37 months, 8 of 21 patients (38%) had sufficient improvement in knee function that a subsequent posterolateral corner reconstruction was not necessary. There was a significant difference in coronal alignment between the preoperative and postoperative mechanical axis action point. There were no significant differences in the preoperative and postoperative posterior tibial slope. Thirteen patients underwent a second-stage ligament reconstruction at an average of 13.8 months after the initial osteotomy procedure. Final postoperative Cincinnati Knee Rating System scores were significantly lower for those patients who required a subsequent posterolateral corner reconstruction than for those patients who did not have a reconstruction. The P value for the preoperative differences between groups was not significant (P = .11). Seven of 9 patients with high-velocity knee injuries required a second-stage reconstruction. Ten of 14 patients (71%) with multiligament knee injuries required a posterolateral corner reconstruction. In contrast, 4 of 6 patients (67%) with an isolated posterolateral corner injury did not require a second-stage ligament reconstruction. CONCLUSION Proximal tibial opening wedge osteotomy can be an effective first method of treatment for patients with chronic combined posterolateral knee injuries and genu varus alignment. Patients with low-velocity knee injuries and isolated chronic posterolateral knee injuries may not require a second-stage soft tissue ligament reconstruction after healing the osteotomy and undergoing a program of rehabilitation.