A biomechanical comparison study of a modern fibular nail and distal fibular locking plate in AO/OTA 44C2 ankle fractures

Abstract

BackgroundA lateral approach with open reduction and internal fixation with a plate is a very effective technique for the majority of distal fibular fractures. However, this open approach for ankle fixation may be complicated by wound dehiscence and infection, especially in high-risk patients. An alternative to plating is an intramedullary implant, which allows maintenance of length, alignment, and rotation and which allows for decreased soft tissue dissection. While there has been clinical data suggesting favorable short-term outcomes with these implants, there is no current biomechanical literature investigating this technology in this particular fracture pattern. This study sought to biomechanically compare an emerging technology with an established method of fixation for distal fibular fractures that traditionally require an extensive exposure.MethodsTen matched cadaveric pairs from the proximal tibia to the foot were prepared to simulate an Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) 44C2 ankle fracture and randomized to fixation with a distal fibular locking plate or intramedullary fibular rod. A constant 700-N axial load was applied, and all specimens underwent testing for external rotation stiffness, external rotation cyclic loading, and torque to failure. The syndesmotic diastasis, stiffness, torque to failure, angle at failure, and mode of failure were obtained from each specimen.ResultsThere was no significant difference in syndesmotic diastasis during cyclic loading or at maximal external rotation between the rod and plate groups. Post-cycle external rotation stiffness across the syndesmosis was significantly higher for the locking plate than the fibular rod. There was no significant difference between the rod and plate in torque at failure or external rotation angle. The majority of specimens had failure at the syndesmotic screw.ConclusionsIn the present cadaveric study of an AO/OTA 44C2 ankle fracture, a modern fibular rod demonstrated less external rotation stiffness while maintaining the syndesmotic diastasis to within acceptable tolerances and having similar failure characteristics.

Novel Elastic Syndesmosis Hook Plate Fixation Versus Routine Screw Fixation for Syndesmosis Injury

“…Many methods of internal fixation are available, including cortical bone screw, absorbable screw, traditional lower tibia and fibula hook, button plate, steel wire binding, and so forth (3,6,12). The widely used screw fixation method has been reported to have several drawbacks, including static fixation, screw breakage, screw loosening, prolonged immobilization and the associated complications, and the requirement for a second operation to remove the screw (6,9). Absorbable screws are synthesized by polylactic acid, which degrades in vivo, resulting in no need for a second operation for screw removal.…”

“…Medial, lateral, and posterior fractures were reduced and fixed with screws and plates. Syndesmotic instability was assessed using the lateral stress test and external rotation stress test under direct visualization in accordance with previous studies (9,17). Finally, 11 patients with a stable syndesmosis were excluded, and 32 patients with an unstable syndesmosis were enrolled in the present study.…”

“…In most external-rotation type ankle fractures, the syndesmosis becomes unstable owing to rupture or dysfunction of the anteroinferior tibiofibular ligament and posteroinferior tibiofibular ligament (7,8). The stability of an injured syndesmosis can be decreased even when the fractures have been well reduced and fixed (9,10). The use of internal fixation for ankle fractures with syndesmosis injury has been widely recommended to avoid early ankle arthrosis and poor functional outcomes (11,12).…”

“…The use of internal fixation for ankle fractures with syndesmosis injury has been widely recommended to avoid early ankle arthrosis and poor functional outcomes (11,12). Transsyndesmosis screw fixation has long been regarded as the reference standard treatment for syndesmotic instability (9,13). However, this method has become controversial, because it provides static fixation and could lead to biomechanical alteration and a series of complications.…”

Posterior malleolus fractures

“…The role of intramedullary fixation for these injuries is an area of evolving interest. [48][49][50] PER injuries are associated with a poor outcome, especially if there is an associated dislocation. 51 Even anatomical reduction does not prevent arthritic change at mediumterm follow-up.…”