The influence of tibial slope on the graft in combined high tibial osteotomy and anterior cruciate ligament reconstruction

Abstract Background Young patients with severe medial osteoarthritis, varus malalignment and insufficiency of the anterior cruciate ligament (ACL) are difficult to treat. The tibial slope has gained attention with regard to osteotomies and ligamentous instability. The purpose was to evaluate the outcome of combined high tibial osteotomy (HTO), ACL reconstruction and chondral resurfacing (CR, abrasion plus microfracture), and to analyse graft failure rates with regard to the tibial slope. Methods Fifty cases (48.9 ± 5.4 years) of combined HTO, ACLR and CR were retrospectively analysed with regard to survival, functional outcome (subjective International Knee Documentation Committee (IKDC) examination form) and subjective satisfaction. The tibial slope was determined on lateral radiographs and analysed with regard to its influence on graft functionality at the time of hardware removal. Results Follow-up rate was 100% after 5.6 ± 1.6 years. No arthroplasties were performed. Subjective IKDC score was 70 ± 18, and 94% were satisfied with the result. The graft was intact in 39 cases (78%), and non-functional in 11 cases (22%). No significant changes were present in pre- and postoperative tibial slope ( P  = 0.811). Graft insufficiency was strongly dependent on tibial slope, with a failure rate of seven percent in cases of postoperative tibial slope  12.5°. Conclusion Combined HTO, ACLR and CR is an effective treatment in these cases. The graft failure rate increases with an increase in tibial slope, in particular when exceeding 12.5°. Level of evidence Case series, Level 4.