Neurostructural correlates of strength decrease following total knee arthroplasty: A systematic review of the...

Area of Science:

• Orthopedics and Rehabilitation
• Neuromuscular Physiology
• Biomedical Engineering

Background:

• Knee extensor muscle weakness is a common complication following total knee arthroplasty (TKA).
• Alterations in neural and structural neuromuscular components are implicated in post-TKA muscle weakness.

Purpose of the Study:

• To investigate maximal voluntary strength (MVS), voluntary muscle activation (VMA), and muscle cross-sectional area (CSA) after TKA.
• To determine the relationship between neural factors (VMA) and structural factors (CSA) with quadriceps strength recovery post-TKA.

Main Methods:

• Systematic literature search and meta-regression analysis of 10 studies involving 289 patients.
• Evaluation of study quality using the Methodological Index for Non-Randomized Studies (MINORS).
• Analysis of quadriceps MVS, VMA, and CSA up to 33 months post-TKA.

Main Results:

• Quadriceps MVS significantly declined early post-TKA, with slow linear recovery.
• VMA and CSA did not show significant alterations post-TKA.
• Meta-regression indicated VMA changes accounted for 39% of quadriceps strength change in the early period (p=0.015).

Conclusions:

• Quadriceps weakness post-TKA is primarily linked to impaired VMA, not reduced muscle size.
• Other neural factors, like hamstring coactivation, may contribute to persistent weakness.
• Rehabilitation strategies should focus on improving VMA and addressing antagonist coactivation for enhanced motor control.