Functional Outcome Based on Mechanical Axis Alignment Following Total Knee Arthroplasty.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Total knee arthroplasty (TKA) is a successful treatment for end-stage knee osteoarthritis, improving pain relief and quality of life.
• Key factors for TKA success include surgical precision, limb alignment, patient selection, and rehabilitation.
• Mechanical alignment of the lower limb is crucial in TKA planning, though optimal alignment remains debated.

Purpose of the Study:

• To assess the reliability of conventional instrumentation in achieving femoral and tibial coronal alignment during TKA.
• To evaluate the functional outcomes of patients with mild deviations (outliers) from neutral mechanical axis alignment post-TKA.

Main Methods:

• Prospective, hospital-based observational study on 60 knees in 42 patients with primary knee osteoarthritis undergoing TKA.
• Patients were evaluated using Knee Society Score and knee flexion range up to six months post-surgery.
• Preoperative and postoperative standing long-leg radiographs were used to compare functional outcomes between inliers and outliers of mechanical axis alignment.

Main Results:

• The mean preoperative mechanical axis alignment angle was 11.88°, changing to 2.90° postoperatively.
• 42 knees were classified as inliers and 18 as outliers.
• No statistically significant differences were observed in mean range of motion (p=0.091) or Knee Society Scores (p=0.740) between inliers and outliers at six months.

Conclusions:

• Mild mechanical axis malalignment does not significantly affect short-term functional outcomes (range of motion, Knee Society Score) following total knee arthroplasty.
• While neutral alignment is the goal, slight deviations do not appear to compromise functional results in the initial postoperative period.