Background

Traditional measurements of hindfoot alignment are based on the tibio-calcaneal angle and do not take the forefoot into account. We have developed an algorithm based on standard radiographs to calculate calcaneal offset using Ground Reaction Force (GRF).

Simultaneous arthrodesis of the ankle and subtalar joints is an established treatment option for combined ankle and subtalar arthritis or complex hindfoot deformities. The use of a curved intra medullary nail has potential advantages in terms of stability, hindfoot alignment and avoidance of the lateral neurovascular bundle.

We devised a comparative description of the results of hindfoot fusion using a curved locking nail before and after the introduction of anatomically specific modifications to the device through a retrospective review of notes and radiographs of patients undergoing simultaneous ankle and subtalar fusion by retrograde intramedullary nailing using an ACE¯ (Humeral Nail. Patients undergoing the same procedure using the Tibiotalocalcaneal [TTC] Nail System [DePuy] were recruited and studied prospectively. The outcome was assessed by a combination of notes review, clinical examination and telephone questionnaire.

Between 1996 and 2004, 71 arthrodeses in 67 patients have been performed. The average follow up is 27 months [3-73] and mean age 58 years. Fifty-two arthrodeses utilised the ACE humeral nail and nineteen used the newer TTC nail. Both nailing systems are locked proximally and distally and provide a short radius laterally directed distal curve. Mean time to union is 4.3 months [3-10]. Average AOFAS hindfoot score post-operatively is 65, with a mean improvement of 40 points from the pre-operative score in the TTC nail group. Post-operative complications included deep infection, amputation and a non-union rate of 10% overall. In the humeral nail group, four symptomatic stress reactions [8%] and three fractures of the tibia [6%] occurred at the tip of the nail. No stress-riser effect has to date been seen in the TTC nail group. Prominent metalwork removal has also been significantly reduced in the TTC nail group.

Our results show hindfoot fusion using a curved intramedullary nail to be an effective technique in complex cases of hindfoot arthritis and deformity. Anatomically specific alterations to the nail have resulted in a significant reduction in certain complications. Alternate proximal locking options in the TTC nail have reduced prominent metalwork and, more significantly, the incidence of stress reactions and fractures appears to have been eliminated.