Review Question - QID 217679

In the setting of ACL rupture, significant varus malalignment should be recognized and corrected with proximal tibial osteotomy before or at the time of ACL reconstruction in order to improve success rates.

Varus malalignment is defined as an angle of >3º between the mechanical axes of the femur and tibia or when the weight-bearing axis of the lower limb passes medial to the tip of the medial tibial spine. Varus malalignment is known to cause progression of medial compartment arthritis, but also increases the risk of failure after ACL reconstruction. Therefore, it should either be addressed prior to, or at the time of ACL reconstruction. The preferred procedure is a high tibial osteotomy, however, multiple techniques exist to achieve correction. Both medial opening and lateral closing wedge osteotomies can be used to correct coronal plane deformities. Lateral wedge osteotomies have the benefit of providing immediate cortical contact for early weight bearing but are often more complicated in that they must be performed in close proximity to the peroneal nerve and proximal tibiofibular joint. It also requires two separate cuts, so is more likely to alter the tibial slope and can make subsequent total knee arthroplasty more technically demanding. Medial opening wedge osteotomy requires one cut and is less likely to affect tibial slope, but does rely on bone graft healing afterwards. In cases where tibial slope is abnormally high (>10-12º), a biplanar osteotomy may be desired to decrease the slope, but this is technically demanding.

Rossi et al. reviewed the role of high tibial osteotomies (HTO) in the varus knee, noting the indications and technique. They emphasize that coronal and sagittal plane alignment must be heavily considered before any kind of correction and that an HTO can be performed concomitantly with ACL reconstruction, meniscal transplant or cartilage resurfacing. They finish by reiterating the importance of mechanical alignment restoration in these types of procedures.

Herman et al. evaluated the HTO in the ACL deficient knee with medial compartment arthritis. They discuss the premise for both coronal and sagittal plane correction in these cases and discuss the advantages/disadvantages to both the medial opening and lateral closing wedge osteotomies. They note that with appropriate patient selection and good technique, most patients have a good outcome after HTO +/- ACL reconstruction.

Savarese et al. reviewed the role of HTO in chronic PCL and posterolateral corner injuries. They note that the sagittal plane correction is equally as important to the coronal plane correction in some cases as this has the ability to significantly alter the biomechanics and stability of the knee joint. Ideally, tibial slope would be decreased with an HTO in an ACL deficient knee and increased with an HTO in a PCL deficient knee.

Incorrect Answers:
Answer 1: ACL reconstruction alone in this patient would have a high rate of failure, given the significant varus malalignment.
Answer 2: Lateral distal femoral opening osteotomy would be better indicated in a patient with valgus, rather than varus deformity.
Answer 4: Biplanar osteotomy is not necessary in this case given the normal tibial slope. While there may be a slight degree of sagittal plane change in any osteotomy, this is not the desired correction.
Answer 5: Unicompartmental knee arthroplasty would not be indicated in a patient who desires to continue playing soccer, has only mild arthritis and a deficient ACL.