Hindfoot alignment at one year after total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Analysis
• Radiographic Evaluation

Background:

• Valgus hindfoot alignment (HFA) has been observed to improve post-total knee arthroplasty (TKA) in patients with varus knee osteoarthritis (OA).
• Understanding the chronological changes in HFA after TKA is crucial for predicting patient outcomes and managing potential complications.

Purpose of the Study:

• To investigate the chronological effects of TKA on hindfoot alignment (HFA).
• To evaluate HFA at multiple time points: preoperatively, 3 weeks post-TKA, and 1 year post-TKA.

Main Methods:

• Radiographic assessment of limb and hindfoot alignment in 71 patients (73 legs) undergoing TKA for varus knee OA.
• Classification of patients into hindfoot varus (<76°) and hindfoot valgus (≥76°) groups based on preoperative varus-valgus angle.
• Comparison of varus-valgus angle changes over time within and between groups.

Main Results:

• In the hindfoot valgus group, the varus-valgus angle significantly decreased from pre-TKA to 1 year post-TKA.
• In the hindfoot varus group, no significant changes in the varus-valgus angle were observed at 3 weeks or 1 year post-TKA compared to pre-TKA.
• These findings suggest differential responses of HFA to TKA based on preoperative alignment.

Conclusions:

• TKA can lead to chronological improvement in HFA for patients with pre-existing hindfoot valgus, indicating compensatory mechanisms.
• Patients with hindfoot varus pre-TKA may not experience HFA improvement, suggesting a loss of compensatory ability.
• Post-TKA ankle pain in patients with hindfoot varus warrants clinical attention and management.