Morphometric variations of the lateral surface of calcaneus: Can standard plate sizes fit all?

Displaced intraarticular fractures of the calcaneum often require plate fixation. The complex fractures are usually fixed with standard lateral plates and are approached via the extensile lateral approach which is fraught with the risk of wound complications. Oversized calcaneal plates produce tension on the wound closure site and can, thus result in wound healing problems. The current study analyses the morphometry of the lateral surface of the calcaneus for the ideal configuration of the calcaneal plates for Indian patients using a CT based analysis of intact calcanei.

Fifty CT based studies of normal calcanei were retrospectively analyzed using Horos® software version 3.3.5. The cross-section of the lateral third of calcaneum was assessed for the morphometric measurements relevant to the dimensions of the standard plating devices for calcaneum. We measured the overall plating length of calcaneum, the vertical heights at the anterior process and calcaneal tuberosity, the height of the posterior facet, the lengths of the anterior process, and the posterior facet. The inclination angles of the posterior facet, cuboid facet were also measured. The findings were compared between male and female cases.

The mean plating length of the calcaneus was 60.06 ± 4.05 mm. The mean vertical height of the anterior process and the calcaneal tuberosity were 24.3 ± 2.71 mm and 39.48 ± 4.73, respectively. The length of the anterior process and the posterior facet were 21.36 ± 1.72 and 25.02 ± 4.17, respectively. The mean Gissane angle and the angle of inclination of posterior facet in relation to the plating length were 118.04 ± 5.99° and 47.3 ± 5.20°. The mean anterior slant angle of the cuboid facet was 96.64 ± 4.39°. Significant differences were observed in the measurements among male and female groups except for the angular parameters.

The current analysis suggests the individual morphometric variations of the lateral plating surface of the calcaneus. Although female calcanei have smaller dimensions compared to male calcanei, the angular parameters are comparable among the two groups. Considering the wide variations in the majority of the morphometric parameters, it is difficult to standardize the plate dimensions. However, a few serial increments in the plate dimensions can help in providing the best fit rather than an ideal fit. Also, the plates should be available with multiple inclination angles of the facet limbs according to the local population variations.