Early arthrogenic muscle inhibition is the dominant predictor of persistent quadriceps inhibition after total knee arthroplasty.

PURPOSE: The purpose of this study is to determine the prevalence of arthrogenic muscle inhibition (AMI) after total knee arthroplasty (TKA) and to identify independent risk factors associated with its persistence during the early post-operative period.

METHODS

This retrospective monocentric study included 229 consecutive patients undergoing primary TKA between January 2024 and May 2025. AMI was assessed pre-operatively and post-operatively at 30 and 60 days using the Sonnery-Cottet (SANTI) clinical classification by trained rehabilitation physicians. Although not specifically validated in TKA patients, this classification was used due to the absence of a validated alternative. Multivariate logistic regression analyses were performed to identify factors associated with AMI.

RESULTS

51.1% were male with a mean age at surgery of 70.7 ± 9.6. Pre-operatively, 9.2% of patients showed signs of AMI. The post-operative prevalence was 44.5% at 30 days and decreased to 19.2% at 60 days. Independent risk factors for AMI at 30 days were body mass index ≥ 30 kg/m2 (odds ratio [OR] 1.97; p = 0.04), symptom duration ≥ 4 years (OR 2.60; p = 0.003), pre-operative AMI (OR 6.08; p = 0.003), post-operative morphine use (OR 2.15; p = 0.01) and pre-operative neutral limb alignment (hip-knee-ankle 175°-185°) (OR 0.38; p = 0.006). At 60 days, AMI persistence was associated with age ≥ 70 years (OR 3.67; p = 0.004), pre-operative AMI (OR 4.41; p = 0.022), Visual Analogue Scale ≥ 7 at Day 7 (OR 3.37; p = 0.044) and AMI at 30 days (OR 15.6; p < 0.001).

CONCLUSION

AMI is a frequent issue after TKA, affecting 45% of patients at 1 month and 20% at 2 months. Its occurrence is associated with pre-operative inhibition, obesity, chronic symptoms, post-operative pain and age.

LEVEL OF EVIDENCE: Level III, retrospective cohort study.