There is a paucity of information on the arterial supply of the navicular, despite its anatomic neighbours, particularly the talus, being investigated extensively. The navicular is essential in maintaining the structural integrity of the medial and intermediate columns of the foot, and is known to be at risk of avascular necrosis. Despite this, there is poor understanding of the vascular supply available to the navicular, and of how this supply is distributed to the various surfaces of the bone. This study aims to identify the key vessels that supply the navicular, and to map the arterial supply to each surface of the bone. Cadaveric limbs (n=10) were dissected to identify source vessels for each navicular. The talus and navicular were removed, together with the source vessels, en bloc. The source vessels were injected with latex and processed using a new, accelerated diaphanisation technique. This quickly rendered tissue transparent, allowing the injected vessels to be visualised. Each navicular was then reconstructed using a digital microscribe, allowing a three dimensional virtual model of the bone to be assessed. The terminal points of each vessel were then mapped onto this model, allowing the distribution of each source vessel to be determined. This study will provide the as yet unpublished information on the arterial supply of the human navicular bone. The data will also give quantifiable evidence of any areas consistently restricted to single-vessel supply, and those consistently supplied by multiple vessels. This may help to explain the propensity of this bone to develop disorders such as osteochondritis, avascular necrosis and stress fractures which often have a vascular aetiology

The arterial supply of the talus has been studied extensively in the past. These have been used to improve the understanding of the risk of avascular necrosis in traumatic injuries of the talus. There is, however, poor understanding of the intra-osseous arterial supply of the talus, important in scenarios such as osteochondral lesions of the dome. Previous studies have identified primary sources of arterial supply into the bone, but have not defined distribution of these sources to the subchondral regions. This study aims to map the arterial supply to the surface of the talus. Cadaveric limbs (n=10) were dissected to identify source vessels for each talus. The talus and navicular were removed, together with the source vessels, en bloc. The source vessels were injected with latex and processed using a new, accelerated diaphanisation technique. This quickly rendered tissue transparent, allowing the injected vessels to be visualised. Each talus was then reconstructed using a digital microscribe, allowing a three dimensional virtual model of the bone to be assessed. The terminal points of each vessel were then mapped onto this model, allowing the distribution of each source vessel to be determined. This study will provide quantifiable evidence of areas consistently restricted to single-vessel supply, and those consistently supplied by multiple vessels. These data may help to explain the distribution and mechanisms behind the development of the subchondral cysts of the talus

MIS (minimally invasive surgery) aims to improve cosmesis and facilitate early recovery by using a small skin incision with minimal soft tissue disruption. When using MIS in the forefoot, there is concern about neurovascular and tendon damage and cutaneous burns. The aim of this anatomical study was to identify the structures at risk with the proposed MIS techniques and to determine the frequency of iatrogenic injury. Materials and Methods. 10 paired normal cadaver feet were used. All procedures were performed using a mini C-arm in a cadaveric lab by 2 surgeons: 1 consultant who has attended a cadaveric MIS course but does not perform MIS in his regular practice (8 feet), and 1 registrar who was supervised by the same consultant (2 feet). In each foot, the surgeon performed a lateral release, a MICA (minimally invasive chevron and Akin) procedure for the correction of hallux valgus, and a minimally invasive DMO (distal metatarsal extra-articular osteotomy) procedure. Each foot was then dissected and photographed to identify any neurovascular or tendon injury. Results. The dorsal medial cutaneous and the plantar interdigital nerves were intact in all specimens. There was no obvious damage to the arterial plexus supplying the first metatarsal head. No flexor or extensor tendon injuries were identified. There is a significant learning curve to performing the osteotomy cuts in the desired plane. In the DMO, the dissection also revealed some intact soft tissue at the osteotomy site indicating that the metatarsal heads were not truly floating. Discussion. Although there has been concern regarding neurovascular and tendon injury, our findings indicate minimal risk, which is consistent with reports in the literature. This study also reflects the learning curve. Conclusion. We suggest that training on cadaveric specimens may be advantageous, particularly, with regard to the plane of the osteotomy

A new method of vascularised tibial grafting has been developed for the treatment of avascular necrosis (AVN) of the talus and secondary osteoarthritis (OA) of the ankle. We used 40 cadavers to identify the vascular anatomy of the distal tibia in order to establish how to elevate a vascularised tibial graft safely. Between 2008 and 2012, eight patients (three male, five female, mean age 50 years; 26 to 68) with isolated AVN of the talus and 12 patients (four male, eight female, mean age 58 years; 23 to 76) with secondary OA underwent vascularised bone grafting from the distal tibia either to revascularise the talus or for arthrodesis. The radiological and clinical outcomes were evaluated at a mean follow-up of 31 months (24 to 62). The peri-malleolar arterial arch was confirmed in the cadaveric study. A vascularised bone graft could be elevated safely using the peri-malleolar pedicle. The clinical outcomes for the group with AVN of the talus assessed with the mean Mazur ankle grading scores, improved significantly from 39 points (21 to 48) pre-operatively to 81 points (73 to 90) at the final follow-up (p = 0.01). In all eight revascularisations, bone healing was obtained without progression to talar collapse, and union was established in 11 of 12 vascularised arthrodeses at a mean follow-up of 34 months (24 to 58). MRI showed revascularisation of the talus in all patients.

We conclude that a vascularised tibial graft can be used both for revascularisation of the talus and for the arthrodesis of the ankle in patients with OA secondary to AVN of the talus.

Cite this article: Bone Joint J 2015; 97-B:802–8.