A new self-designed locking plate assembly for treatment of Sander II & III calcaneal fractures

Abstract

Objective To report a new self-designed locking plate assembly suitable for treatment of displaced calcaneal fractures of Sanders types Ⅱ &Ⅲ via sinus tarsi approach. Methods We designed a new locking plate assembly suitable for treatment of displaced calcaneal fractures of Sanders types Ⅱ & Ⅲ via sinus tarsi approach. Its biomechanical performance was tested by standard electronic and mechanical devices. From March 2014 to October 2015, 18 patients with displaced calcaneal fracture were treated with our self-designed new locking plate assembly. They were 14 men and 4 women, aged from 32 to 66 years (average, 50.4 years). All the fractures were unilateral closed ones, with 7 cases of the left side and 11 ones of the right side. By the Sanders classification, 14 cases belonged to type Ⅱ (8 to type Ⅱa, 4 to type Ⅱb and 2 to type Ⅱc) and 4 to type Ⅲ (2 to type Ⅲab, one to type Ⅲac and one to type Ⅲbc). The Bohler angle, Gissane angle, and height, width and length of the calcaneus were measured and compared at preoperation, postoperative 3 months and final follow-ups. The clinical outcomes were evaluated using Maryland foot score system atfinal follow-ups. Results This new locking plate assembly could tolerate a maximum vertical load of 1,396.03 N and a maximum horizontal anti-bending load of 427.15 N. It broke after it had been subjected to 93,003 loadings in a repeated 500 N stress test. All the 18 patients were followed-up for an average of 9.3 months (from 6.0 to 13.5 months). Follow-ups at 3 months postoperation showed significant improvements in Bohler and Gissane angles and calcaneal height, width and length compared with pre-operative parameters (P 0.05). Maryland foot scores demonstrated 12 excellent cases, 3 good ones and 3 fair ones. No incision infection, implant failure, nonunion or malunion happened in this series. Conclusions This new locking plate assembly suitable for sinus tarsi approach can be used in clinic because it has advantages of easy placement, rigid fixation, satisfactory functional recovery of the foot and limited complications. Key words: Calcaneus; Surgical procedures, minimally invasive; Fracture fixation, internal; Bone plate assembly