Temporal changes in quadriceps and hamstring strength and flexibility following total knee arthroplasty

Area of Science:

• Orthopedics and Rehabilitation Science
• Biomedical Engineering
• Kinesiology

Background:

• Quadriceps and hamstring dysfunction are common in knee osteoarthritis (OA) and after total knee arthroplasty (TKA).
• Muscle flexibility changes and their impact on postoperative recovery after TKA are not well understood.
• Strength deficits are frequently studied, but flexibility requires further investigation.

Purpose of the Study:

• To evaluate temporal changes in quadriceps and hamstring strength and flexibility.
• To compare these changes from preoperatively to one year after TKA.
• To compare outcomes with healthy controls.

Main Methods:

• Assessed quadriceps and hamstring strength using a handheld dynamometer.
• Measured flexibility using standardized muscle length tests.
• Collected data preoperatively and at 6 weeks, 3, 6, and 12 months post-TKA, comparing with healthy controls.

Main Results:

• Preoperatively, both strength measures were significantly lower than controls.
• Strength declined further at 6 weeks post-TKA, especially quadriceps.
• While strength and flexibility improved significantly from 3 to 12 months, they remained lower than controls at 12 months.

Conclusions:

• Quadriceps and hamstring strength and flexibility improve significantly in the first year after TKA.
• Residual quadriceps deficits persist compared to healthy individuals.
• Early, progressive rehabilitation emphasizing long-term quadriceps strengthening and flexibility is recommended for optimal TKA outcomes.