Correlation between frontal knee alignment and bone resection thicknesses during total knee arthroplasty without precision-enabling device: a retrospective study.

INTRODUCTION

Proper knee alignment is critical for optimizing postoperative function and implant longevity in total knee arthroplasty (TKA). While robotic-assisted surgery offers precision in bone resections, most surgeons still rely on conventional instrumentation. This study evaluates the relationship between pre- and postoperative frontal knee alignment and bone resections in TKA performed without precision-enabling devices to establish a correlation between thickness of resection and frontal angular correction.

MATERIALS AND METHODS

This retrospective, single-center study analyzed data from patients undergoing TKA for end-stage osteoarthritis between June 2021 and April 2024. Intraoperative cuts were measured in a standard way. All procedures were performed by a single experienced surgeon without precision-enabling devices. Preoperative and six-week postoperative weight-bearing goniometry and anteroposterior (AP) radiographs were collected. The cohort consisted of 130 patients: 69 varus (= 177° HKA), 30 neutral (177°-183° HKA) and 31 valgus (= 183° HKA) knees. Patients were 36.9% male, with a mean age of 70.1 years (SD 8.2) and a BMI of 30.8 kg/m (SD 5.6). Hip-knee-ankle (HKA) angle, anatomical and mechanical tibiofemoral angles and joint line convergence angles (JLCA) were measured. Statistical analysis was conducted to determine correlations between resection measurements and angular parameters.

RESULTS

The correlation between tibial resection (ΔT) and medial proximal tibial angle modification measured on goniometry (ΔMPTA(g)) followed a linear regression with a Spearman's correlation coefficient (r = 0.553). A weak positive correlation was observed between ΔT and ΔMPTA on AP radiographs (r = 0.505), as well as between distal femoral resection (ΔDF) and lateral distal femoral angle modification (ΔLDFA(g)) on goniometry (r = 0.350) and on AP radiographs ΔLDFA(s) (r = 0.187).

CONCLUSION

This study suggests a moderate correlation between tibial resection thickness and angular correction in the coronal plane. However, the high variability observed indicates that surgical planning should not rely solely on this correlation.