Posterior arthroscopic subtalar arthrodesis without bone graft preserves hindfoot height and function

Purpose: This study aimed to assess hindfoot height (HFH) changes 12 months after posterior arthroscopic subtalar arthrodesis without bone grafting. We hypothesized that HFH reduction would be minimal and would not impact fusion or functional results. Methods: A retrospective study was conducted on 39 patients who underwent posterior arthroscopic subtalar arthrodesis. HFH was measured on CT scans preoperatively and at 12 months postoperatively. Inter- and intra-observer reliability of the measurement was also assessed as a secondary outcome. Clinical outcomes included pain (numeric analog scale, NAS) and AOFAS Ankle-Hindfoot scores. Subtalar fusion ratios were evaluated via CT. Results: Mean HFH loss was 0.85 ± 1.1 mm (range, 0–5 mm). The average fusion ratio was 72 ± 30%. Pain and AOFAS scores significantly improved (NAS: −4 ± 2, p < 0.0001; AOFAS: +31 ± 13, p < 0.0001). No correlation was found between HFH loss and fusion ratio or clinical outcomes. HFH loss > 1 mm was more frequent in women and smokers. HFH measurement on CT showed excellent inter- and intra-observer reliability (ICC intra: 0.989; inter: 0.976). Conclusions: Posterior arthroscopic subtalar arthrodesis without bone graft results in minimal hindfoot height loss, with no negative impact on subtalar fusion or functional outcomes. This technique reliably preserves hindfoot alignment and provides excellent clinical results. While the assessment of hindfoot height on CT demonstrated excellent inter- and intra-observer reliability, this was a secondary finding and supports the utility of CT-based measurements in the postoperative evaluation of subtalar arthrodesis.