Intraoperative evaluation of medial intercuneiform instability after Lapidus arthrodesis: intercuneiform hook test.

The presence of intercuneiform instability is not routinely inspected within the overall surgical management of hallux valgus and has therefore been underreported as a potential cause of recurrence. We sought to demonstrate the incidence of this unique type of proximal instability to state its potential importance in the correction and definitive management of hallux valgus in patients with moderate to severe intermetatarsal angles with superimposed hypermobility. A total of 34 patients underwent 38 tarsometatarsal arthrodeses for hallux valgus correction and were retrospectively reviewed for 36 months from May 2007 to May 2010. The incidence of intercuneiform instability was 73.68% and was determined by the findings of the intraoperative "hook" test. The high rate of proximal instability could warrant consideration for routine intermetatarsal arthrodesis as a component of this procedure. A technique for evaluating the presence of intercuneiform instability after Lapidus arthrodesis is also presented.