Joint Reaction Forces Decrease Following Total Knee Arthroplasty up to 12-Months Post-Surgery

Area of Science:

• Orthopedics
• Biomechanics
• Biomedical Engineering

Background:

• Mechanical loading is crucial for total knee arthroplasty (TKA) component fixation.
• Understanding joint reaction forces (JRFs) pre- and post-TKA is vital for assessing outcomes.

Purpose of the Study:

• To estimate medial, lateral, and total knee JRFs before and at 3, 6, and 12 months after TKA.
• To analyze changes in JRFs during level gait and sit-to-stand activities.

Main Methods:

• EMG-informed musculoskeletal modeling was used to estimate JRFs.
• Models were scaled using CT scans and weight-bearing X-rays for lower limb alignment.
• 22 participants undergoing primary TKA for osteoarthritis were studied.

Main Results:

• JRF peak values and impulses significantly decreased at 3 months post-TKA for both activities.
• These forces did not return to preoperative levels by 12 months.
• Level gait showed a mean total JRF peak reduction of 0.72 BW at 3 months.

Conclusions:

• Post-TKA patients do not regain preoperative JRFs, even at 12 months.
• Altered loading patterns may contribute to decreased bone mineral density around TKA components.
• These findings have clinical relevance for long-term TKA component stability.