Minimal Clinically Important Differences for Patient-Reported Outcomes After TKA Depend on Central Sensitization

Area of Science:

• Orthopedics
• Pain Management
• Rehabilitation

Background:

• Central sensitization (CS) is a poorly understood phenomenon in patients undergoing total knee arthroplasty (TKA).
• Its influence on patient-reported outcome measures (PROMs), specifically the minimal clinically important difference (MCID) after TKA, remains unknown.
• Understanding CS's role is crucial for interpreting TKA outcomes.

Purpose of the Study:

• To investigate the impact of central sensitization (CS) on the minimal clinically important difference (MCID) for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score.
• To compare MCID achievement rates between patients with and without CS following TKA.

Main Methods:

• A cohort of 422 patients undergoing unilateral TKA with 2-year follow-up was analyzed.
• Central sensitization was assessed using the Central Sensitization Inventory (CSI).
• MCID for the WOMAC score was calculated using anchor-based, distribution, and change difference methods, including ROC analysis, for patients with and without CS.

Main Results:

• The MCID for the WOMAC total score was higher in patients with CS (23.4 points via change difference; 29.5 points via ROC) compared to those without CS (14.7 points via change difference; 26.5 points via ROC).
• MCID achievement rates for WOMAC pain, function, and total scores were significantly lower in patients with CS across both calculation methods (p < 0.05).

Conclusions:

• Central sensitization (CS) increases the minimal clinically important difference (MCID) required for meaningful improvement in WOMAC scores after TKA.
• Patients with CS demonstrate a reduced rate of achieving the MCID following total knee arthroplasty.
• These findings highlight the importance of considering CS when evaluating TKA outcomes and setting patient expectations.