SLR - November 2015 - Timothy P. McConn
Reference: Kodama N, Takemura Y, Ueba H, Imai S, Matsusue Y. A New Form of Surgical Treatment for Patients with Avascular Necrosis of the Talus and Secondary Osteoarthritis of the Ankle. Bone Joint J. 2015 Jun; 97-B(6): 802-8.Scientific Literature Review
Reviewed By: Timothy P. McConn, DPM
Residency Program: West Penn
Podiatric Relevance: Avascular necrosis (AVN) of the talus has historically been a rather tough clinical condition to treat both conservatively as well as surgically. For the early stages, core decompression has shown to be an effective procedure. However, upon collapse of the talus, few treatment options exist. Tibiotalar arthrodesis is a current option to address the latter, but there is a risk of a pseuodarthrosis, which can pose challenges when performing an arthrodesis. Kodoma et al describes a technique using a vascularized bone flap of the distal tibia as a viable option for treatment of AVN of the talus with or without underlying OA.
Methods: A cadaveric and clinical/radiologic study was carried out in two steps to assess preservation of the talus using a vascularized tibial flap in the treatment of AVN, as well as the results of tibiotalar arthrodesis for treatment of AVN with secondary OA. The first portion consisted of a cadaveric study of the distal tibia vascular network for identification and planning of vascularized bone flap. The second portion of the study assessed eight patients with isolated AVN of the talus and 12 patients with AVN of the talus with secondary OA who all underwent a vascularized bone flap for treatment. Patients were assessed clinically both pre-operatively and at final review using the Mazur ankle grading system and the AOFAS ankle/hindfoot scale. Post-operative union of the graft and collapse of the talus were assessed radiographically. For the eight patients with preservation of the talus, MRI was performed at six to sixty months post-operatively in order to evaluate talar revascularization.
Results: Cadaveric study: The anterior tibial artery was found to be directly above the tibia at a mean of 4.9 cm proximal from the level of the ankle joint. Lateral malleolar artery was confirmed in all cadavers at the level of the ankle joint. It was determined that maximum vascularized bone graft that could there be elevated was 2 cm wide, 1.5 cm deep, and 5 cm long. Clinical/Radiographic results: For outcomes regarding preservation of the talus at 26 months mean follow-up, the mean pre-operative score was 39 points (Mazur grading system), which significantly improved to 81 post-operatively. In all eight, Hawkins sign was confirmed at least 2.5 months post-op as well as revascularization confirmed by MRI at a mean of 24 months. For the arthrodesis cohort with a mean follow-up of 34 months, the Mazur score significantly improved from 32 pre-op to 72 post-op.
Conclusions: Vascularized bone grafting should be considered when conventional bone grafting fails in the management of AVN of the talus. The cadaveric portion of this study confirmed that a vascularized tibial flap can be safely elevated. Radiographic and MRI findings support biological heeling within the talus 12 to 15 months post-op. With significant positive outcome scores in both cohorts, the authors showed that a tibial vascularized bone flap can be used for both preservation of the talus and arthrodesis in patients with OA secondary to AVN of the talus.