Minimal Detectable Change for Motor Function Tests in Patients with Knee Osteoarthritis

Area of Science:

• Orthopedics
• Rehabilitation Medicine
• Biostatistics

Background:

• Accurate measurement of motor function is crucial for evaluating interventions in knee osteoarthritis (OA).
• The minimal detectable change (MDC) quantifies measurement error, essential for detecting true functional improvements.
• The five-time sit-to-stand test (FTSST) and 5-m walk test (5mWT) are common motor function assessments.

Purpose of the Study:

• To determine the minimal detectable change (MDC) for the FTSST and 5mWT in patients with knee OA.
• To establish reliable thresholds for detecting meaningful changes in motor function post-intervention.

Main Methods:

• A cross-sectional study involving 83 knee OA patients (mean age 73.7 years).
• Two trials of the FTSST and 5mWT were administered.
• Intraclass correlation coefficients (ICCs) and MDC95 were calculated for test reliability and error margins.

Main Results:

• High reliability was found: ICCs were 0.90 (FTSST), 0.83 (5mWT time), and 0.81 (5mWT speed).
• MDC95 values were 1.71s for FTSST, 0.99s for 5mWT time, and 0.36 m/s for 5mWT speed.

Conclusions:

• Observed changes exceeding 1.71s (FTSST) or 0.99s/0.36m/s (5mWT) indicate genuine functional improvement in knee OA.
• These MDC values aid clinicians in interpreting motor function test results and assessing intervention effectiveness.
• The findings support evidence-based clinical decision-making for knee OA management.