Contralateral knee effect on self-reported knee-specific function and global functional assessment: data from the...

Area of Science:

• Orthopedics
• Rheumatology
• Biomedical Engineering

Background:

• Knee osteoarthritis (OA) significantly impacts physical function and quality of life.
• Assessing functional limitations in knee OA is crucial for effective management.
• The influence of contralateral knee pain on outcome measures is not well understood.

Purpose of the Study:

• To investigate how pain in one knee affects assessments of the other knee in individuals with knee OA.
• To compare patient-reported outcomes and objective functional tests in different knee pain scenarios.

Main Methods:

• A matched case-control study design was employed using data from the Osteoarthritis Initiative.
• Subjects with one painful and one pain-free knee (discordant) were compared to those with bilaterally pain-free or bilaterally painful knees.
• The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function score, Physical Activity Scale for the Elderly (PASE), and functional performance tests were analyzed.

Main Results:

• WOMAC physical function scores differed significantly in the pain-free knees of discordant cases compared to bilaterally pain-free knees (P=0.003).
• WOMAC scores also differed significantly in the painful knees of discordant cases compared to bilaterally painful knees (P<0.001).
• Functional performance tests, particularly the chair stand test, showed significant differences between discordant cases and both control groups, indicating higher sensitivity.

Conclusions:

• Contralateral knee pain status influences the WOMAC physical function score, even for the knee without pain.
• The repeated chair stand test is a sensitive objective measure for distinguishing between different knee pain statuses in knee OA.
• These findings highlight the importance of considering contralateral knee pain when interpreting functional outcomes in knee OA.