Kinematic alignment in total knee arthroplasty restores the native anatomy, with a joint line parallel to the ground on a standing view.

BACKGROUND

Kinematic alignment (KA) total knee arthroplasty (TKA) restores the native alignment of the knee joint. The present study compared the pre-and post-operative limb alignment of patients undergoing KA-TKA. It evaluated joint line orientation and obliquity on weight-bearing radiographs with the ground as reference.

METHODS

56 patients treated with KA-TKA from January to December 2022 were prospectively included. The coronal orientation of the TKA was evaluated on pre- and postoperative anteroposterior long-leg weight-bearing radiographs. For each patient, measurements were made of the hip-knee-ankle (HKA) angle, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), arithmetic HKA (aHKA), and joint line obliquity (JLO).

RESULTS

The mean LDFA of all patients was 84.6° ± 1.7° pre-operatively and 84.5° ± 1.5° post-operatively (P = 0.06). The mean MPTA of all patients was 83.5° ± 1.6° pre-operatively and 85.1° ± 2.1° post-operatively (P = 0.07). The mean HKA of all patients was 172° ± 2° pre-operatively and 175° ± 2° post-operatively (P = 0.47). The difference in LDFA, MPTA, HKA, JLO and aHKA pre-operatively and post-operatively was not statistically significant.

CONCLUSION

There were no differences in pre- and postoperative radiographic measurements and alignment of the lower limb in patients undergoing KA-TKA, with the joint line orientation parallel to the ground on weight-bearing radiographs in all patients. Longer-term follow-up is necessary to assess the functional outcome and study implant survival of KA-TKA.