Surgical outcomes of insertional Achilles tendinopathy: A comparison of techniques with and without FHL transfer

Insertional Achilles tendinopathy may require surgery when nonoperative treatment fails. Flexor hallucis longus (FHL) tendon transfer is used as an adjunct in advanced insertional degeneration.

To compare 1-year outcomes, minimal clinically important difference (MCID) achievement, and complications between FHL transfer with debridement/retrocalcaneal ostectomy and debridement/ostectomy alone.

Retrospective comparative cohort study (indication-based group allocation).

Thirty consecutive patients treated surgically between 2017 and 2023 were reviewed retrospectively. Preoperative magnetic resonance imaging (MRI) planimetry guided selection: patients with >50% degeneration underwent FHL transfer plus debridement and retrocalcaneal ostectomy (n = 15), whereas patients with ≤50% degeneration underwent debridement and ostectomy alone (n = 15). Outcomes were assessed preoperatively and at 1 year using the Victorian Institute of Sport Assessment-Achilles (VISA-A), American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS-AH), Foot and Ankle Ability Measure (FAAM), Foot and Ankle Disability Index (FADI), and visual analog scale (VAS) pain. MCID was calculated using a distribution-based method.

Both groups improved significantly at 1 year (all p < 0.05). No between-group differences were observed for VAS, AOFAS-AH, FAAM, or FADI (all p > 0.05). The FHL group had higher postoperative VISA-A scores (65.9 ± 15.3 vs 49.9 ± 19.7; p = 0.031) and higher VISA-A MCID achievement (93.3% vs 66.6%; p = 0.046). Minor wound complications occurred in 4 patients (2/15 in each group).

Both surgical approaches improved pain and function at 1 year. In this indication-based cohort, adding FHL transfer for >50% MRI-defined degeneration was associated with higher Achilles-specific function (VISA-A) without increased wound complications.