Open-wedge high tibial osteotomy is considered to be an effective treatment for medial compartmental osteoarthritis. It is generally admitted that tibial slope increases after open-wedge high tibial osteotomy and decreases after closing-wedge high tibial osteotomy. Young patients with anterior cruciate ligament (ACL) deficiency along with medial compartment osteoarthritis need a combined procedure of ACL reconstruction along with high tibial osteotomy to regain physiological knee kinematics and to avoid chondral damage.
We retrospectively analysed data from 30 patients who underwent arthroscopic ACL reconstruction along with medial opening-wedge osteotomy from Jan 2004 to June 2012 with a minimum follow up of 2 years. The pre-operative and post-operative posterior tibial slopes were measured. Functional outcome was analysed using clinico-radiological criteria, IKDC scoring and Lysholm score.
Post-operative patients improved both clinically and functionally. The patients who had posterior tibial slope >5° decrease, compared to patients who had less <5° decrease, had better functional scores (IKDC and Lysholm score), which was statistically significant (p < 0.05).
Our study has shown that decreasing the tibial slope >5° compared to pre-operative value has functionally favourable effect on the reconstructed ACL graft and outcome. It is known that increasing slope causes an anterior shift in tibial resting position that is accentuated under axial loads. This suggests that decreasing tibial slope may be protective in an ACL deficient knee. Hence by placing the tricortical graft posterior to midline in the opening wedge reduces the posterior tibial slope and thereby reduces the stress on the graft leading to better functional outcome.