Abstract
Introduction
Medial calcaneal displacement osteotomy with an FDL tendon transfer is a common method of correcting pes planus deformity secondary to grade II tibialis posterior dysfunction. There is currently no evidence that calcaneal displacement alters the centre of pressure in the foot from a medial to a more central position as the normal shape is reconstituted.
Materials and Methods
We prospectively evaluated 12 patients undergoing flatfoot reconstruction. Each patient had a preoperative AOFAS hindfoot score, pedobariographs and antero-posterior and lateral radiographs. This was repeated 6 months following surgery.
Results
An angle (α) between the central axis of the foot (calcaneum to 2nd metatarsal head) and the centre of pressure (COP) was calculated for each patient both pre and post operatively and analysed using the Shapiro Wilk and the Students t test. Pressures directly under the 1st and 5th metatarsal heads and the calcaneum were also recorded and the pre and post operative differences analysed. The mean change in α angle is 6.1° (p < 0.01). The mean increase in pressure on the 1st metatarsal head is 460kPa (p = 0.08). The pressure changes on the 5th metatarsal head and the calcaneum are not statistically significant. The mean AOFAS score increases from 39.2 preoperatively to 82.8 postoperatively (p = 0.0019). The Meary angle improves from a mean of 12.7° to 5.7° (p = 0.027) and the calcaneal pitch improves from15.1° to 18.2° (p = 0.12)
Conclusion
The medial displacement calcaneal osteotomy is able to significantly lateralise the centre of pressure in the foot and also increases the pressure under the 1st metatarsal head to more closely represent the parameters of the normal foot. The shape of the foot as judged radiographically and the clinical outcomes (AOFAS) are also improved.
