https://doi.org/10.1177/1071100718793172 Foot & Ankle International® 1–9 © The Author(s) 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1071100718793172 journals.sagepub.com/home/fai Article Chronic Achilles tendon ruptures usually present as a result of a misdiagnosed, neglected, or unrecognized acute rup- ture. The acute Achilles tendon rupture is a commonly missed diagnosis, and the patient may present with a chronic rupture after 4 to 6 weeks from the injury. 8,9,15,16,38 The ten- don ends are frequently retracted, and considerable func- tional morbidity is usually associated. Although conservative management is possible, surgeons agree that chronic Achilles tendon ruptures should be surgically treated when possible. 12,23,25 Operative management of chronic Achilles tendon ruptures is challenging, and numerous techniques have been described. The goal of surgery is to restore Achilles tendon function, and on the grounds of the tendon gap size, several open techniques have been reported: V-Y and turn- down flaps, 1,6 tendon transfers (peroneus brevis, 32 flexor digitorum longus, 26 flexor hallucis longus 37 ), autografts 793172FAI XX X 10.1177/1071100718793172Foot & Ankle InternationalVega et al research-article 2018 1 Human Anatomy and Embriology Unit, University of Barcelona, Barcelona, Spain 2 Foot and Ankle Unit, Hospital Quirón Barcelona and, iMove Traumatology Tres Torres, Barcelona, Spain 3 Groupe de Recherche et d‘Etude en Chirurgie Mini-Invasive du Pied et de la Cheville (GRECMIP), Merignac, France 4 Orthopaedic and Trauma Surgery, Hospital Universitario 12 de Octubre, and Hospital Quirón Ruber, Madrid, Spain 5 Surgical Department, University Complutense of Madrid, Madrid, Spain 6 Club Atletico Boca Juniors, Buenos Aires, Argentina 7 Foot and Ankle Unit, Department of Trauma and Orthopaedic Surgery, Royal London Hospital, Barts Health NHS Trust, London, United Kingdom 8 Faculty of Health Sciences at Manresa, University of Vic—Central University of Catalonia, Manresa, Barcelona, Spain Corresponding Author: Jordi Vega, MD, Orthopaedic and Trauma Surgery, Hospital Universitario 12 de Octubre, and Hospital Quirón Ruber, Plaza Alfonso Comín 5, 08023 Barcelona, Spain. Email: jordivega@hotmail.com Endoscopic Flexor Hallucis Longus Transfer for Chronic Noninsertional Achilles Tendon Rupture Jordi Vega, MD 1,2,3 , Jesus Vilá, MD, PhD 4,5 , Jorge Batista, MD 6 , Francesc Malagelada, MD 7 , and Miki Dalmau-Pastor, PodD, PT, PhD 1,3,8 Abstract Background: Operative management of chronic Achilles tendon ruptures is challenging, and numerous techniques have been described. Risk of infection and wound breakdown have been described after open techniques, and minimally invasive methods have been proposed to avoid them. The aim of this study was to describe the clinical and radiological results obtained after endoscopic flexor hallucis longus (FHL) tendon transfer in patients with chronic Achilles tendon rupture. Methods: Between 2012 and 2015, a total of 22 patients were endoscopically treated for chronic Achilles tendon rupture. Mean age was 69 years (range, 59-84 years). Mean follow-up was 30.5 months (range, 18-46 months). Preoperative magnetic resonance imaging (MRI) was obtained and tendon gap measured. An MRI was obtained at 9 to 12 months following surgery to evaluate Achilles tendon changes. Results: Preoperative MRI examination showed a mean tendon gap of 6.3 cm (range, 3-10.7 cm). The MRI control was obtained only in 12 patients, and a normal or close to normal Achilles tendon was observed in all but 1 patient. The mean American Orthopaedic Foot & Ankle Society score increased from 55 preoperatively (range, 26-75) to 91 (range, 74-100) at final follow-up. All patients returned to their daily activities without difficulties. No patients reported complaints or symptomatic deficits of great toe flexion strength. No major complications were encountered. Conclusion: Chronic Achilles tendon ruptures were successfully treated by an all-endoscopic procedure. The endoscopically assisted FHL transfer provided excellent results while benefiting from the minimally invasive procedure advantages. However, it entailed some technical challenges and may not be suitable for less experienced surgeons. Level of Evidence: Level IV, retrospective case series. Keywords: Achilles tendon, chronic tendon rupture, flexor hallucis longus tendon, tendon transfer, hindfoot endoscopy