A windows technique for sustentaculum tali screw fixation using the sinus tarsi approach for calcaneal fractures: a cadaveric study

INTRODUCTION

The minimally invasive approach for displaced intra-articular calcaneal fractures is significantly reducing postoperative wound complications. One minimally invasive method, the sinus tarsi approach (STA) has been increasingly widely used. STA is, however, challenging due to its technical demands and the risk of injury to the sural nerve (SN). The purpose of this study was to identify the SN and its branches including their anatomical relationship to the STA as well as to describe an anatomical windows technique for STA including determination of the safe angle for screw insertion into the sustentaculum tali fragment.

METHODS

Thirty-two adult cadaveric legs were disarticulated at the knee and unpaired. STA was performed on each specimen. The anatomy and distribution of the sural nerve and its branches were identified in relation to the incision. Three surgical windows were identified and selected. Kirshner wires were inserted in pairs via each of the windows towards the center of the sustentaculum tali. The safe angle for wire insertion in relation to the SN or its branches was then measured as well as the appropriate intraoperative drilling angle.

RESULTS

The plantar branch presented in the distal window in none of the samples, while the dorsal branches presented in 37.5% and the main SN presented in only 6.25%. In the middle window, the dorsal branch presented most often (43.75%) followed by the plantar branch (25.00%) and the SN (21.88%). In the proximal window, the SN presented in 100% of the samples, while the dorsal branch presented in none and the plantar branch presented in about 15.63% of the specimens. All three windows had their own acceptable average angle for screw insertion towards the sustentaculum tali.

CONCLUSIONS

The distal window is the safest for surgical approach and for calcaneal surgery screw fixation in terms of avoiding sural nerve injury. In addition, that window provides a wide working angle for screw fixation.

The distribution pattern of the dorsal cutaneous nerves of the foot and its clinical implications

Iatrogenic injury to subcutaneous nerves on the dorsum of the foot is an established risk factor during the surgical procedures resulting in postoperative pain, sensation loss and painful neuroma. Previous studies have reported on the distribution pattern of the superficial peroneal, deep peroneal and sural nerves (SNs) and their branches with various classifications about specific populations. The purpose of the present study was to evaluate the distribution pattern and classification of the nerves on the dorsum of the foot and analyze the location of these nerves into five zones with clinical implications. Fifty-four lower limbs of fresh frozen cadavers were used in the present study. The anatomical patterns of the superficial peroneal, deep peroneal, SN and their branches were classified into eight, two and five patterns respectively. Type VI pattern, a classic distribution pattern of the superficial peroneal nerve was the most frequent type with a prevalence of 13 limbs (25.00%). In Zone 5, where the arthroscopic portal placements for the first metatarsophalangeal joint arthrodesis, 29 limbs (55.77%) showed three nerve branches located in this zone. The results of the present study provide anatomical knowledge that may help the surgeon to choose the appropriate treatment for their patients and reducing the rate of complications in surgery.