Title : Value of pre-operative imaging of the flexor hallucis longus for achilles tendon transfer surgery
Abstract:
Introduction: Flexor hallucis longus (FHL) tendon transfer is the method of choice in reconstructing chronic neglected Achilles tendon rupture (ATR). In routine FHL tendon transfer surgery, the FHL is excised at the level of the Master knot of Henry and transferred into a bone tunnel in the calcaneus bone. Using this technique, only the distal FHL tendon is visualised and abnormalities of the FHL muscle belly and proximal tendon may be missed.
Method: In our institution, a tertiary orthopaedic referral centre, we have encountered a varied spectrum of abnormalities involving the FHL on MRI and therefore, the FHL is an important review area for the musculoskeletal radiologist. We decided to specifically analyse fatty infiltration of the FHL and performed a retrospective review of 225 consecutive MR images of ankle performed at our institution during 2017 for ankle pain and analysed the extent of fatty infiltration of the FHL muscle using a modified Goutallier classification.
Results: We performed a retrospective review of 225 consecutive MR images of ankle performed at our institution during 2017 for ankle pain and analysed the extent of fatty infiltration of the FHL muscle using a modified Goutallier classification. The average age of the cohort was of the cohort was 44 years (10-82 years) with a female predominance (130 female and 95 males). 44% of the cohort had normal FHL, 42.7% demonstrated grade 1 fatty atrophy and further small proportion of patients with grade 2 (8.4%), grade 3 (3.1%) and grade 4 (1.8%) fatty atrophy.
Conclusion: Preoperative radiological assessment of the FHL tendon is important to establish that the FHL muscle and tendon are normal and intact and hence suitable for transfer surgery. The FHL is an important review area for the musculoskeletal radiologist and operating surgeon. With our findings, we can also hypothesise that fatty infiltration is a common finding in the FHL muscle. We suggest cross sectional imaging to assess the muscle belly prior to tendon transfer surgery for chronic ATR.
