Application of a Ni-Ti arched shape-memory connector in unstable lateral malleolus fractures: A retrospective study

Purpose

To compare the outcomes of the arched shape-memory connector (ASC) only fixation and the lateral one-third tubular plate fixation in managing unstable Type A or B lateral malleolus fractures according to the Weber (AO) classification, and to evaluate the feasibility and reliability of ASC only fixation in treating these fractures.

Methods

From January 2010 to January 2015, 148 patients with Type A or B (Weber (AO) classification) lateral malleolus fractures treated with the arched shape-memory connector (ASC) only fixation or lateral plate fixation were included. There were 66 patients in the ASC only fixation group and 82 patients in the lateral plate group. Intergroup differences were absent regarding patient and fracture characteristics. The incision length, complete-union time, major complications and complaints, incidence of hardware removal, and final radiographic and functional evaluations were compared.

Results

The follow-up time averaged 18.2 months in the ASC fixation group and 17.2 months in the lateral plate group. The ASC only fixation group had significantly decreased wound infection (4.55% versus 14.63%) and skin necrosis (none versus 7.32%). Of patients who underwent ASC only fixation 3.03% reported lateral ankle pain, 7.58% received palpable hardware, and 3.03% reported hardware irritation, while the corresponding observations in the lateral plate group were 19.51%, 54.88%, and 14.63%, respectively, representing a statistical difference. Furthermore, compared with the lateral plate group, the incidence of hardware removal was markedly lower in the ASC fixation group (12.12% versus 30.49%). In terms of reduction accuracy, complete-union time, and AOFAS scores, no appreciable differences were observed.

Conclusions

ASC only fixation is a reliable alternative for managing Type A or B lateral malleolus fractures, leading to fewer soft tissue complications, fewer hardware complaints, and a reduced need for hardware removal, and a reduced need for hardware removal. In addition, ASC can be used for augmented plate fixation in certain comminuted fracture patterns.