Evaluation of total knee arthroplasty using isokinetic testing.

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Rehabilitation Medicine

Background:

• Total knee arthroplasty (TKA) is a common procedure for degenerative joint disease.
• Objective muscle function assessment following TKA remains under-reported.
• Preoperative muscle deficits in the involved knee are common in TKA candidates.

Purpose of the Study:

• To objectively evaluate muscle strength deficits before and after TKA using isokinetic testing.
• To assess the correlation between isokinetic muscle testing, gait analysis, and functional knee outcome scales.
• To inform TKA rehabilitation program planning and patient outcome evaluation.

Main Methods:

• Isokinetic testing (Cybex II) was performed on 68 patients undergoing unilateral TKA.
• Gait mat analysis and the Hospital for Special Surgery knee rating scale were used for functional assessment.
• Muscle strength (flexion/extension peak torque) and limb symmetry were analyzed preoperatively and postoperatively.

Main Results:

• Significant preoperative deficits in knee flexion and extension strength were observed.
• Hamstring strength recovery to contralateral levels occurred within 7-12 months post-TKA.
• Quadriceps deficits persisted up to two years post-TKA, affecting gait symmetry.
• Isokinetic testing correlated well with gait analysis; a balanced hamstring-to-quadriceps ratio improved gait symmetry.
• The Hospital for Special Surgery knee rating scale showed lower reliability in functional outcome assessment.

Conclusions:

• Objective isokinetic muscle testing provides valuable data for TKA planning and rehabilitation.
• Restoration of balanced hamstring and quadriceps strength is crucial for normal gait resumption after TKA.
• Targeted strengthening of quadriceps may be necessary for optimal functional recovery post-TKA.