Total knee arthroplasty in patients with substantial deformities using primary knee components

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Constrained implants in total knee arthroplasty (TKA) for severe deformities have drawbacks.
• Minimally invasive surgery (MIS) offers potential advantages.

Purpose of the Study:

• To evaluate the efficacy of a minimally invasive far medial subvastus approach with interchangeable posterior stabilized (PS) implants for TKA in severe varus/valgus deformities.
• To assess if this combination allows for adequate soft tissue balancing with minimal constraint and no residual instability.

Main Methods:

• Retrospective review of 51 patients undergoing primary TKA for severe varus/valgus deformities between 2009-2013.
• Utilized a minimally invasive far medial subvastus approach with interchangeable PS implants (Vanguard).
• Soft tissue releases performed using piecrust needling technique; assessed preoperative and postoperative alignment and clinical outcomes.

Main Results:

• Successful correction of deformities, improving mean mechanical alignment to 179.5° (3.0°).
• Postoperative deviations from neutral alignment were minimal (9 varus, 3 valgus >3°).
• Excellent clinical scores reported at final follow-up.

Conclusions:

• A minimally invasive far medial subvastus approach combined with interchangeable PS implants and piecrust needling is effective for TKA in severe varus/valgus deformities.
• This technique achieves good outcomes, improved alignment, and stability without excessive constraint.