Coronal limb alignment and indications for high tibial osteotomy in patients undergoing revision ACL reconstruction.

BACKGROUND: Failed ACL reconstruction frequently is accompanied by irreparable medial meniscal tear and/or visible osteoarthritis (OA) in the medial tibiofemoral joint. Thus, assessment for the presence of varus malalignment is important in caring for patients in whom revision ACL reconstruction is considered.

QUESTIONS/PURPOSES: We determined whether patients undergoing revision ACL reconstruction (1) have more frequent varus malalignment coupled with more severe degrees of medial meniscal injury and/or medial tibiofemoral OA, and (2) would meet potential indications for high tibial osteotomy more frequently than patients undergoing primary ACL reconstruction.

METHODS: We compared 58 patients undergoing revision ACL reconstruction and 116 patients undergoing primary ACL reconstruction. The mechanical tibiofemoral angle and the weight loading line (%) of the knee were measured. Additionally, radiographic degrees of OA in the tibiofemoral joints, and meniscal conditions were assessed. Then, proportions of potential candidates for high tibial osteotomy between the two groups were compared based on the following indications: (1) weight loading line less than 5%, (2) weight loading line less than 25% and medial tibiofemoral OA Kellgren-Lawrence Grade 3 or greater, or (3) weight loading line less than 25% and Kellgren-Lawrence Grade 2 medial tibiofemoral OA plus subtotal or total medial meniscectomy status.

RESULTS: The revision ACL reconstruction group had more frequent varus malalignment in terms of proportion of knees with more varus mechanical tibiofemoral angle than varus 5° (19% versus 8%, p = 0.029) and knees with weight loading line less than 25% (22% versus 9%, p = 0.011). This group also had more frequent high-grade injury of the medial meniscus (34% versus 16%, p = 0.007) and tended to have more frequent higher-grade radiographic OA at the medial tibiofemoral joint (19% versus 9%, p = 0.076). The percentage of patients meeting potential indications for high tibial osteotomy was greater in this group (14% versus 2%, p = 0.003).

CONCLUSIONS: We found that many patients undergoing revision ACL surgery may be reasonable candidates for concurrent high tibial osteotomy to address concomitant alignment and OA issues in the medial compartment. However, whether that additional intervention is offset by added risk and morbidity should be the focus of a future study, as it cannot be answered by a study of this design.