Precontoured, low-profile plates with fixed dorsiflexion angles are becoming increasingly popular for first metatarsophalangeal joint fusion. We have concerns that the routine use of a precontoured plate can lead to excessive clinical dorsiflexion. The aim of our study was to investigate the relationship between the first metatarsophalangeal joint dorsiflexion intramedullary angle and the angle formed at the dorsal cortices where the plate is applied. We hypothesized that the dorsal cortical angle was significantly less dorsiflexed than the intramedullary angle. We measured both angles on lateral weightbearing radiographs of 40 consecutive individuals presenting with forefoot symptoms. The results demonstrated that the mean dorsal cortical angle was significantly smaller (mean 0.2° plantarflexion) compared with the intramedullary angle (mean 10.6° dorsiflexion; p < .001). The interobserver and intraobserver reliability of both the intramedullary and the dorsal cortical measurements was very good. In conclusion, the dorsal cortical angle is, on average, 10.8° smaller than the intramedullary angle, with a mean angle of almost 0°. This finding should be considered when selecting plates for first metatarsophalangeal joint fusion.
Keywords: arthrodesis; dorsal cortical angle; first metatarsal; great toe; hallux; internal fixation.
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