Does Malrotation of the Tibial and Femoral Components Compromise Function in Kinematically Aligned Total Knee Arthroplasty?

Implant malalignment may be a risk factor for poor patient-reported outcomes measures (PROMs) following total knee arthroplasty (TKA).

Postoperative surveys were administered to assess PROMs regarding satisfaction, pain, and function in 262 patients who underwent surgery at 4 centers in the U.S. and U.K (average age, 67.2) at a mean 5.5 years after primary TKA. Postoperative distal femoral angle (DFA), proximal tibial angle (PTA), and posterior tibial slope angle (PSA) were radiographically measured, and outliers were recorded. PROMs were compared between patients with aligned versus malaligned knees using univariate analysis.

Patients with DFA, PTA, and PSA outliers were more likely to experience similar or decreased activity levels postoperatively than patients with no alignment outliers, as were patients with 1 or 2 outliers of any kind (P < .05). Patients with DFA, PTA, and PSA outliers were significantly more likely to be dissatisfied with their ability to perform activities of daily living (ADLs), as were patients with 1 or 2 outliers of any kind (P < .05). Patients with DFA and PSA outliers were more likely to be dissatisfied with their degree of pain relief, as were patients with 2 outliers of any kind (P < .05). Finally, patients with DFA and PSA outliers, as well as those with 1 outlier of any kind, were more likely to be dissatisfied with their overall knee function (P < .05).

DFA, PTA, and PSA outliers represent a significant risk factor for decreased satisfaction with activities of daily living(ADLs), pain relief, and knee function, as well as decreased activity levels.

Level III.

This chapter contains discussion and video links that assist the surgeon in performing calipered kinematically aligned (KA) total knee arthroplasty (TKA) with specific manual instruments, a verification worksheet, and a decision tree. The treatment of 4726 primary TKAs performed from 2009 through 2019 with KA to restore the patient’s prearthritic joint lines regardless of knee deformity and without ligament release by the senior author provides the background. During this time, 4316 had retention, and 410 had an excision or an unintended transection or tibial detachment of the posterior cruciate ligament (PCL). This experience evolved into a highly reproducible surgical technique that works best with the retention of the PCL. The first section discusses tips for exposing the knee. The second section describes the use of caliper measurements and verification checks that set the femoral component coincident to the patient’s prearthritic or native distal and posterior femoral joint lines with minimal flexion. The third section describes the use of caliper measurements and verification checks that set the tibial component coincident to the prearthritic tibial joint line. The fourth introduces a decision tree that, when followed, restores the native tibial compartment forces, laxities (except anterior laxity), and tibiofemoral and patellofemoral kinematics, thereby balancing the calipered KA TKA. The fifth section discusses the management of the severe fixed valgus deformity and the knee with flexion laxity from injury to the PCL. The educational objective is to encourage those surgeons that use manual, patient-specific, navigation, and robotic instrumentation to retain the PCL, not release the collateral ligaments, measure bone resections with a caliper, perform verification checks, and follow a decision tree to align and balance the calipered KA TKA reproducibly.