Quadriceps/hamstrings co-activation increases early after total knee arthroplasty.

Area of Science:

• Orthopedics
• Biomechanics
• Rehabilitation Science

Background:

• Quadriceps and hamstrings weakness and co-activation are common after total knee arthroplasty (TKA), potentially impacting functional performance.
• The influence of surgery and rehabilitation on muscle activation during walking early after TKA remains unclear.

Purpose of the Study:

• To examine muscle strength and activation during walking in patients before and at one and six months after TKA.

Main Methods:

• Ten TKA patients and ten healthy controls underwent strength testing and surface electromyography during a six-minute walk test (6MW).
• Assessments included quadriceps and hamstrings strength, co-activation, and muscle on/off timing.
• Comparisons were made between groups, limbs, and changes following TKA surgery.

Main Results:

• TKA patients reported greater knee pain and exhibited weaker quadriceps and hamstrings strength compared to controls, both pre- and post-surgery.
• Patients showed significant side-to-side strength differences and greater quadriceps/hamstrings co-activation pre-operatively and one month post-TKA.
• Quadriceps deactivation was delayed in patients compared to controls before and one month after TKA, with controls walking farther.

Conclusions:

• Significant differences in muscle strength, co-activation, and timing exist between TKA patients and controls before and early after surgery.
• Rehabilitation interventions aimed at enhancing muscle strength and optimizing activation patterns are essential for restoring proper muscle firing post-TKA.