Frailty is associated with prolonged hospitalization and inferior patient-reported outcomes after acute quadriceps tendon rupture: A multicenter cohort study.

Background

Quadriceps tendon rupture is a functionally devastating injury frequently affecting patients with high comorbidity burden and impaired physiological reserve. Frailty represents an age-independent construct of diminished physiological resilience; its impact on hospitalization and long-term functional outcomes after quadriceps tendon rupture remains poorly defined.

Methods

We retrospectively analyzed 67 adults who underwent surgical repair or reconstruction for acute quadriceps tendon rupture (≤4 weeks) at four tertiary centers between 2019 and 2023. Pre-operative frailty was quantified using the 5-item modified frailty index (mFI-5) and the 9-point clinical frailty scale (CFS). CFS was assigned retrospectively by two orthopedic surgeons using dual-reviewer consensus (κ=0.82). Primary outcomes were length of hospital stay (LOS) and functional recovery at ≥12 months (Lysholm Knee Scoring Scale); Knee Injury and Osteoarthritis Outcome Score and complications were secondary. Multivariable models were a priori restricted (six predictors for LOS, four for Lysholm; observations-per-predictor ≈11: 1 and ≈17: 1) and adjusted for age, sex, body mass index, comorbidity burden, surgical technique, and follow-up.

Results

Mean age was 57.5±12.1 years; 79.1% male. Higher mFI-5 scores were associated with prolonged LOS (r=0.404, p<0.001); in adjusted models, each 1-point increase in mFI-5 predicted a 1.26-day longer stay (95% confidence interval [CI] 0.61-1.90; adjusted R2=0.337). At a mean follow-up of 25.5 months, the mean Lysholm score was 52.2±17.5. CFS was independently associated with poorer recovery (r=-0.328, p=0.007); each 1-point CFS increase corresponded to a 4.32-point decrement in Lysholm (95% CI -6.98 to -1.67; adjusted R2=0.163). A sensitivity analysis excluding reconstruction cases (n=6) yielded essentially unchanged effect sizes (mFI-5 → LOS: β=1.22; CFS → Lysholm: β=-4.18). No significant association was detected between either frailty metric and complications (rate 10.4%, 7 events); however, this analysis was underpowered and should be interpreted with caution.

Conclusion

Frailty is associated with prolonged hospitalization and poorer patient-reported outcomes after surgical repair of quadriceps tendon rupture. Integration of mFI-5 and CFS into routine pre-operative evaluation may refine surgical planning, discharge coordination, and rehabilitation intensity.