What question did this study set out to answer?

The study aims to evaluate the accuracy of stylus-derived tibial measurements during total knee arthroplasty.

May 22, 2026Open Access

Limited Accuracy of Tibial Stylus Measurements in Conventional Total Knee Arthroplasty

Key Points

The study aims to evaluate the accuracy of stylus-derived tibial measurements during total knee arthroplasty.
Included 109 patients undergoing primary total knee arthroplasty with the Legion system.
Measured intraoperative resection depth using stylus and compared it with caliper-measured osteochondral thickness.
Correlations and agreements were analyzed using Spearman’s rank correlation and Bland–Altman analysis.
Mean stylus-indicated resection depth was 4.24 ± 2.15 mm; mean caliper-measured thickness was 5.75 ± 2.30 mm.
After adjusting for saw blade kerf, mean resection thickness increased to 7.12 ± 2.30 mm.
Moderate correlation observed (ρ = 0.540, p < 0.001) with wide limits of agreement in Bland–Altman analysis.

Abstract

Background: Accurate tibial resection is important for component alignment and implant longevity in total knee arthroplasty (TKA). Despite the utilization of standardized instrumentation, discrepancies between predicted and actual resection depth persist. In the current study, the correlation between stylus-derived measurements and actual tibial resection thickness is analyzed. Methods: A total of 109 patients undergoing primary TKA using the Legion system (Smith 95% CI: −3.22 to −2.47 mm) indicating a tendency toward over-resection. The correlation between stylus-indicated depth and actual osteochondral resection thickness was moderate (ρ = 0.540, p < 0.001). Bland–Altman analysis showed wide 95% limits of agreement from −6.75 to 1.05 mm. Conclusions: Stylus-based predictions of tibial resection depth show limited accuracy. Stylus-based measurements should be interpreted with caution and complemented by intraoperative verification.

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