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Updated: Jan 28, 2026
In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty
Published on: May 5, 2023
Design-dependent associations between quadriceps strength and sagittal knee biomechanics after posterior-stabilized
Ryota Fujii1,2, Hyunho Lee2, Christopher Stickley3
1Department of Orthopaedic Surgery, Kobari General Hospital, Noda, Japan.
Purpose:
Single-radius (SR) and multi-radius (MR) femoral components are widely used in posterior-stabilized total knee arthroplasty (TKA). While previous studies have compared these designs primarily using clinical outcomes or basic kinematics, the relationship between quadriceps strength and dynamic sagittal-plane knee biomechanics remains insufficiently understood.
Methods:
This prospective exploratory cohort study included 31 posterior-stabilized TKAs (SR: 16 knees; MR: 15 knees). Patients were evaluated at 6 months and 1 year postoperatively. Knee extension strength was measured using a handheld dynamometer. Sagittal-plane biomechanics during level walking, stair ascent, and stair descent were assessed using three-dimensional motion capture. External knee flexion moment (KFM) and KFM impulse were calculated. Associations between quadriceps strength and sagittal-plane biomechanical variables were analyzed using Spearman correlation coefficients.
Results:
No significant between-group differences were observed in demographics or clinical activity levels. In the SR group, no significant associations were identified between quadriceps strength and sagittal-plane biomechanical variables at any postoperative time point. In contrast, the MR group demonstrated a moderate positive correlation between knee extensor strength and stair-descent knee flexion moment (KFM) impulse at 6 months postoperatively (r = 0.498, p < 0.05), which was not observed at 1 year postoperatively. During stair ascent, a significant positive correlation between knee extensor strength and the first peak KFM was observed in the MR group at 1 year (r = 0.606, p < 0.05).
Conclusions:
This exploratory study demonstrated design-dependent associations between quadriceps strength and sagittal-plane knee biomechanics after posterior-stabilized TKA. While no significant between-group differences were observed in clinical or absolute biomechanical outcomes, task- and time-dependent strength-biomechanics associations were identified in the MR group, whereas no such associations were observed in the SR group, suggesting potential clinical relevance in patients with delayed quadriceps recovery.
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