Because of dissatisfaction with the ability of the medial displacement calcaneal osteotomy to restore arch anatomy, a number of authors have studied the effects of lengthening the relatively short lateral column of a planovalgus foot with forefoot abduction. This concept was originally popularised by Evans for treating over-corrected clubfeet and most of the older papers describe the treatment of paediatric flatfoot deformities.
Two techniques have been described:
- A transverse osteotomy of the calcaneum 10mm proximal to the calcaneocuboid joint is distracted to correct forefoot abduction and a tricortical iliac crest bone graft inserted.
- Distraction fusion of the calcaneocuboid joint also lengthens the lateral column and avoids a second procedure for OA. However, the non-union rate is about 15%.
A transverse osteotomy of the calcaneum 10mm proximal to the calcaneocuboid joint is distracted to correct forefoot abduction and a tricortical iliac crest bone graft inserted. Raines (1998) examined the structures at risk from osteotomies 5, 10 and 15 mm from the calcaneocuboid joint. The peroneal tendons were more at risk with the more distal osteotomies and risk to other soft tissue structures was similar with each osteotomy position. The 10mm osteotomy, however, was the only one that avoided damage to the anterior and middle facets of the subtalar joint in cadavers which had separate facets. Therefore, the osteotomy should be made 10mm from the calcaneocuboid joint.
Osteotomy preserves calcaneocuboid movement but Cooper (1997) found a marked increase in the pressures in the calcaneocuboid joint, raising concern that patients might eventually need calcaneocuboid fusion for OA. Momberger (2000) using a better flatfoot model, suggested that calcaneocuboid pressure is increased in the flatfoot anyway and that calcaneal osteotomy does not chage this. The reported rate of calcaneocuboid fusion for OA after osteotomy is probably about 5%, although not all papers report this clearly. Pressures in the subtalar joint may also be increased.
Reported series have described the use of cortico-cancellous graft to keep the osteotomy open. With the advent of wedged plates it is not clear whether bone graft is actually necessary to obtain healing. The amount of correction is usually judged by the hidfoot-midfoot alignment. Sangeorzan (1993) found that the most important effect of lateral column lengthening was an improvement in the talonavicular coverage angle. It is interesting that while most surgeons lengthen by about 1cm or more, Sangeorzan found that none of his 7 patients had more than 4mm of lengthening at union.
There is a tendency for the forefoot to supinate as the osteotomy is opened (van der Krans 2006). Some patients have degree of fixed forefoot supination anyway (Truro stage 2C). Supination during osteotomy opening should be resisted, but lateral column lengthening will not itself correct supination and a medial column procedure may need to be added (Chi 1999, van der Krans 2006, Bolt 2008)
Various fixation techniques have been used. Many foot plating systems have an H-plate designed for fixing these osteotomies but plate prominence can be a problem not only in shoes but interfering with wound healing.
There has been only one (retrospective) comparative series between osteotomy and fusion (Thomas 2002). All patients also had FDL transfer to the navicular. Mean AOFAS scores were 81 for fusion and 88 for osteotomy. Overall the results of the fusions were no better than the osteotomies, they took longer to recover and had more complications. However, the numbers were small and more osteotomies than fusions were lost to follow-up. The authors appear to adopted the fusion procedure later than the osteotomy, though without abandoning the osteotomy. Frustratingly, they do not comment on this change in practice, whether the treatment groups were comparable or whether there were particular indications for the fusions in later patients, or implications for the results.
Similar results have been reported from single-procedure studies (Hintermann 1999, Moisier-LaClair 2001, van der Krans 2006). Moisier-LaClair’s series had anterior and posterior (as described in the previous section) osteotomies, intending to share the displacements between the two osteotomies and reduce skin tension; wound problems may have been less frequent but 14% failed because of persistent pain. DiDomenico (2011) also described 34 combined anterior and (percutaneous) posterior calcaneal osteotomies, 23 of whom also had medial column procedures. Improvements were noted in standard radiological indices, but clinical results were not reported. There were one wound healing problem and two delayed unions
Deland (2010) reported that patients who had lateral column pain after lengthening osteotomy had increased pressures under the lateral column compared to those without pain, although the mechanism was unclear.
Myerson (2004) found that patients with severe deformities did less well with transfer plus posterior osteotomy, and this is the group who are thought to benefit from lateral column lengthening. Series of lateral column lengthening report improvement in the arch more consistently, but the clinical scores appear similar and all studies report a lot of wound problems and lateral column pain, which may offset the possibility of improved correction. There have been no published series comparing the calcaneal osteotomy plus tendon transfer to lateral column lengthening. It may be that the lateral procedure is more effective in patients with more severe deformities (Truro stage 2b), but so far there is no evidence on which to judge this hypothesis.