Abstract
Arthrodesis of both the ankle and the hindfoot has been discussed in the literature since the early part of the last century. Techniques have been modified substantially since these early discussions, though complications remain a frustrating element in patient management. Early procedures relied on molded plaster casts to hold fixation in corrected positions. Successful outcomes were hampered by loss of reduction in these casts and subsequent malunions. In addition, motion within these casts lead to a high rate of nonunion between the opposed bony surfaces. The era of internal fixation allowed compression across arthrodesis sites, enhancing union but creating a host of technical errors leading to unsatisfying results.
Malunion is also seen in post-traumatic situations. In particular, non-operative management of calcaneus fracture (or other hindfoot fractures) leads to not only arthritis of the involved joint surfaces, but malunion complicating successful fusion. Fusion in-situ leads to a high level of patient dissatisfaction, leading surgeons to challenging deformity correction while trying to achieve successful arthrodesis in compromised joints.
This lecture will focus on two types of malunion, one iatrogenic, one acquired. Revision triple arthrodesis (iatrogenic) can range from simple to challenging. A variety of studies document patient dissatisfaction following correction via this technique, ranging from Graves and Mann (1993) where the highest dissatisfaction rate was in highest in valgus malunion, to Sangeorzan and Hansen (1993), who found a 9% failure rate, most with varus malunion. The precarious balance required to create a plantigrade foot via triple arthrodesis with pre-existing deformity leaves even the most skilled surgeon challenged. As such, this component of the lecture will focus on recognition and correction of malunion based on a structured algorithmic approach we first presented in 1997. This algorithm is based on recognition of the apex of the deformity, and creating osteotomies to achieve balance.
We reviewed 28 patients who returned for follow-up examination who received treatment through this algorithm and found a statistically significant improvement in pre- and postoperative AOFAS ankle/hindfoot score, from an average of 31 points preoperatively to 59 postoperatively (p<0.01). All patients united, and all stated they would undergo the revision procedure again. Comparisons of pre- and postoperative shoe wear modification demonstrated a statistically significant improvement (p=0.01). Preoperatively, 20 patients required restrictive devices such as ankle foot orthoses and orthopaedic shoes. Postoperatively, only 1 patient required such a restrictive device. In fact, 17 patients required no modifications to their shoe wear at all.
The second component to this lecture will assess acquired hindfoot deformity, from malunion created by calcaneus fractures. A 2005 JBJS study by Brauer, et.al. found operative management resulted in a lower rate of subtalar arthrodesis with a shorter time off work compared to non-operative management. Removing the expense of time off work still netted a $2800 savings for operative management over non-operative management. Sanders echoed these thoughts in a JBJS 2006 paper, suggesting patients with displaced intra-articular calcaneal fractures may benefit from acute operative treatment given the difficulty encountered in restoring the calcaneal height and the talo-calcaneal relationship in symptomatic calcaneal fracture malunion. Thus, with these challenges in mind, the goal of this component of the lecture is to introduce methods to achieve balance and union with calcaneus fracture malunion. Vertically oriented multiplanar calcaneal osteotomy may assist the surgeon in avoiding the higher non-union rate associated with bone-block arthrodesis procedures. In this vein, the challenges associated with bone block subtalar arthrodesis will be explored.
