Sagittal alignment following ankle and tibiotalocalcaneal arthrodesis: A retrospective review of radiological and patient reported outcomes

P Singh, A Still, K Malhotra, S Patel, N Cullen, M Welck

Aims: This study aimed to examine the relationship between sagittal plane alignment and patient-reported outcomes measures (PROMs) in patients undergoing ankle / tibiotalocalcaneal (TTC) arthrodesis.

Methods: Single-centre, retrospective review of patients undergoing ankle or TTC arthrodesis over an 8-year period. Measurements were performed on WBCT images: anterior/medial distal tibial angles (aDTA / mDTA), coronal talar tilt, and sagittal tibial-sole angle (TSA), tibio-talar angle (TTA), and tibio-calcaneal inclination angles (TCA). These were obtained from 50 normal patients and 42 patients undergoing fusions pre-operatively and at 3 and 12 months postoperatively. MOxFQ scores were collected pre- and post-operatively and post-operative subjective alignment was recorded.

Results: Mean age was 56±12.9 years and BMI was 30.5±5.1 kg/m2. Ankle arthrodesis was performed in 35/42 (83.3%) patients. Pre-operative deformity was >10 degrees from normal in sagittal/coronal plane in 8 patients (19%) and moderate (±5 degrees) in 8 patients (19%). There was no difference between normal group and post-operative group TSA (p=0.058), although there was a lower (more dorsiflexed) TTA (5.0 degrees, p<0.001) and TCA (2.9 degrees, p=0.037) in post-operative scans. There was no difference in sagittal post-operative position by type of fixation, ankle/ TTC, arthroscopic/open or degree of pre-operative deformity. Significant improvements were observed in all MOxFQ domains (p<0.01). Age / BMI / final position did not influence PROMs. On regression analysis, a lower TSA was the only factor predictive for a subjective feeling of a dorsiflexed foot (p=0.021, Exp(B)=0.472).

Conclusions: Regardless of pre-operative deformity, Ankle/TTC arthrodesis is effective at restoring sagittal alignment and improves PROMs. Although there is some variation in TTA, TCA may compensate partially for this resulting in a balanced foot (TSA). TSA influenced perceptions of sagittal balance, particularly when dorsiflexed. It is important to strive for optimal sagittal alignment in ankle and TTC arthrodesis, which may be judged intra-operatively by the TSA.