Pertinent Insights On Treating Lapidus Nonunions

Author(s): 
By Graham A. Hamilton, DPM

     In cases in which surgeons noted intraoperative transverse or sagittal plane hypermobility after the standard crossed two-screw fixation, they stabilized the intercuneiform joint by inserting a third screw from the medial base of the first metatarsal to the second cuneiform. For primary Lapidus arthrodesis, Sangeorzan and Hansen used two 3.5 mm cortical screws for fixation.3 A 3.5 mm cortical screw crossed the first metatarsocuneiform joint to provide compression whereas the second screw served as a derotational screw, crossing from the first metatarsal base to the second cuneiform.

     In a biomechanical study, Cohen, et al., compared load to failure with a dorsal locking plate design versus standard crossed screw fixation. Screw fixation for first tarsometatarsal arthrodesis created a stronger and stiffer construct than did the dorsal H-locking plate.8 For four patients, surgeons used a single 3.5 mm or 4.0 mm positional screw along with a dorsal or dorsomedial four- or five-hole neutralization plate. Plate designs consisted of a standard 1/3 tubular compression plate or a reconstruction plate.

A Guide To Post-Op Care And Contraindications

     In our study, 13 patients (76 percent) undergoing revision received immediate post-op bone stimulation. Twelve patients received external bone stimulation while one received internal bone stiumulation. Four patients received no bone stimulation and all of these went on to solid union. While there are various arguments on bone stimulation technology, a subject for another discussion, this modality is a useful adjunct for revision cases. However, one cannot use this as an alternative to meticulous surgical technique.

     In regard to postoperative care, all patients wore a short-leg, non-weightbearing cast for six weeks. If early radiographic consolidation occurred at this time, we had the patients progress to a removable walking boot for four more weeks.
     Patients demonstrating incomplete radiographic consolidation at six weeks remained non-weightbearing in a short-leg cast for at least four more weeks. At an average of 10 weeks postoperatively, patients advanced to regular supportive shoes with a gradual return to regular activities as tolerated.

Understanding Key Factors That Affect Bone Healing

     We utilized statistical analysis to determine whether gender, fixation, bone stimulation and smoking were predictive of or associated with bone healing. Active smoking in the perioperative period was a predictor of nonunion. None of the other variables demonstrated any statistical association.

     The adverse effects of cigarette smoking on bone healing are well documented.2,7,9 Almost 40 percent of patients who had failed primary Lapidus procedures, requiring revision for a symptomatic nonunion, were smokers. All three failed revision procedures occurred in patients who were smokers as well. McInnis and Bouche noted a 12 percent symptomatic nonunion rate in 32 feet. Two of the three cases were cigarette smokers.4 Similarly, Coetzee, et al., noted three cases of nonunion (11.5 percent), all of which occurred in smokers.7 They concluded that smoking should be a relative contraindication to the modified Lapidus procedure.

     For this reason, we selectively avoid performing primary Lapidus arthrodesis and revision arthrodesis in active smokers at our institution. Patients who do smoke and require a Lapidus arthrodesis should undergo aggressive preoperative counseling and cessation support. The patient needs to be smoke-free for approximately three months before undergoing surgery. From the data in this report, there is further evidence to view active smoking by a patient as a relative contraindication to performing revision surgery.

     Compliance with strict, early non-weightbearing postoperatively is essential in achieving successful union. All three cases, which resulted in nonunion, had repeated documentation in chart review of premature weightbearing in the immediate postoperative period despite disciplined counseling. Other authors have also reported higher rates of nonunion due to earlier weightbearing in the postoperative course.3,5,10

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