The Effect of Lateral Cortex Disruption and Repair on the Stability of the Medial Opening Wedge High Tibial Osteotomy

Abstract

Background Medial opening wedge high tibial osteotomy is gaining popularity as a treatment option for medial compartment degenerative disease in the young, active patient. One of the potential technical pitfalls of this procedure is inadvertent disruption of the lateral tibial cortex during distraction at the osteotomy site. Purpose (1) To investigate the effect of lateral cortex disruption on stability during medial opening wedge high tibial osteotomy and (2) to evaluate 3 different methods of repair of the disrupted lateral cortex. Study Design Controlled laboratory study. Methods A total of 50 validated replicate tibias were evaluated in a medial opening wedge high tibial osteotomy model. Specimens were divided into 5 groups: (1) control, or intact lateral cortex (n = 10); (2) disrupted lateral cortex (n = 10); (3) lateral cortex repaired with 1 staple (n = 10); (4) lateral cortex repaired with 2 staples (n = 10); and (5) lateral cortex repaired with a periarticular plate and screws (n = 10). Specimens were placed in compression and torsion under physiologic loads, and stiffness and micromotion were calculated. Results Disruption of the lateral cortex resulted in a 58% reduction in axial stiffness and a 68% reduction in torsional stiffness compared to control specimens (P<. 05). Disruption of the lateral cortex also resulted in increased micromotion at the osteotomy site. All 3 methods of repair of the lateral cortex restored stiffness and micromotion values to those of the control group (P<. 05). Conclusions Instability at the osteotomy site may contribute to the high rate of delayed union or nonunion associated with medial opening wedge high tibial osteotomy. Repair of the lateral tibial cortex by each of these techniques restored stability to the osteotomy site in this replicate tibia model and might be effective in clinical use. However, more studies are needed to further explore the relationship between lateral cortex disruption and patient outcomes in the clinical setting before definitive conclusions can be drawn.