# Changes in Physical Function and Locomotive Syndrome Status in the Postoperative Period Following Total Hip and Knee Arthroplasty

## TL;DR

This study shows that while basic mobility remains stable after hip or knee replacement surgery, muscle strength and locomotive syndrome worsen over time, especially after 10 years.

## Contribution

The study reveals time-dependent deterioration in muscle power and locomotive syndrome beyond 10 years post-surgery, even after adjusting for confounding factors.

## Key findings

- Very long-term postoperative patients showed significantly worse 5-CS times and higher GLFS-25 scores compared to short-term patients.
- Severe locomotive syndrome increased from 4.8% in short-term to 30.6% in very long-term patients.
- Bilateral surgery cases increased to 61.1% in the very long-term group, likely reflecting the progression of hip dysplasia.

## Abstract

Objective: This study aims to examine changes in physical function and locomotive syndrome (LS) status at different postoperative stages after total hip arthroplasty (THA) and total knee arthroplasty (TKA), emphasizing long-term functional maintenance and prevention of mobility decline.

Methods: This cross-sectional study included 118 THA or TKA patients categorized into four postoperative duration groups: short-term (<24 months, n=21), mid-term (24 to 59 months, n=29), long-term (60 to 119 months, n=32), and very long-term (≥120 months, n=36). Physical function was measured using handgrip strength, the five-chair stand (5-CS) test, one-leg standing time, usual walking speed, and a short physical performance battery. The LS status was assessed using the stand-up test, two-step test, and 25-question Geriatric Locomotive Function Scale (GLFS-25).

Results: Despite similar evaluation ages (73 to 74 years), the very long-term group had significantly longer 5-CS times (10.8±3.5 vs 8.5±2.4 seconds in short-term, p=0.04) and higher GLFS-25 scores (15.0±9.0 vs 8.5±5.7, p=0.005). Severe LS (stage 3) increased from 4.8% in the short-term to 30.6% in the very long-term group (p=0.04). In the THA subgroup analysis (n=94), these differences remained significant after adjusting for age at surgery, BMI, and bilateral surgery status (adjusted p=0.028 for 5-CS, p<0.001 for GLFS-25). Basic mobility functions such as walking speed and balance remained stable across periods. Bilateral surgery cases increased with longer postoperative duration, reaching 61.1% in the very long-term group (p=0.02).

Conclusions: Joint arthroplasty provides sustained benefits in basic mobility functions over extended periods. However, muscle power-dependent functions and LS severity show time-dependent deterioration, particularly beyond 10 years post-surgery. This decline persists after adjustment for confounders and occurs even in unilateral cases, indicating a true time-related phenomenon. The high prevalence of bilateral surgery in long-term follow-up likely reflects the natural history of hip dysplasia but does not fully explain functional decline. These findings underscore the importance of long-term monitoring and targeted interventions to maintain muscle strength, especially beyond 10 years post-surgery.