Mechanical contribution of the fibula to torsion stiffness in the lower extremity

Abstract

The role of the fibula in rotational stability of the lower extremity, taking into account the intact knee joint and tibia, to the best of our knowledge, has not been investigated. A cadaver study was designed to determine the torque transfer down the lower extremity, with and without the fibula. Six fresh, frozen human cadaver legs were used. The knee joint was left intact and the foot disarticulated. An external rotation up to 5 degrees , coupled with axial compression, was applied to the femur passing through the knee joint in extension and down the lower extremity to the fixed distal end, where torque (N m) was measured via a load cell. Each specimen was further tested with the fibula, cut 4 cm from the distal end, and finally with the entire fibula disarticulated at the proximal end and removed. To achieve 5 degrees rotation, torques reached 1.82 N m (SD, 0.66 N m). When the fibula was cut, the torque reduced a small yet significant amount of 5%. With the entire fibula removed, the torque reduction was significant and more pronounced at 11%. The fibula provided a small yet significant role in torsion stability. From this study, where the biomechanical characteristics of the fibula is explicated, it is hoped that this information will have use in further understanding the biomechanical role of the fibula, especially, in relation to the altered mechanics associated with lower limb pathology involving a deficient fibula.

Anterolateral and Medial Locking Plate Stiffness in Distal Tibial Fracture Model

“…7,13,14 Although their material properties are not completely representative of cadaveric tibia, they similarly offer much less inter-specimen variability. 2,7,10,13,18,25,28 The combined attributes of uniform geometry, accurate biomechanical properties, and reduced inter-specimen variability limits the number of factors that could contribute to inconsistencies in the experimental study including different anatomic geometries and bone quality found in cadaveric human tibiae. Because of the uniformity in specimens, we were able to use plates and screws of the same size for each tibia, insuring bicortical purchase with each installation, similar levels of fracture reduction, and similar positioning of the plates, while following standard operative technique.…”

“…Although the tibia is primarily responsible for resisting compressive loads, some uncertainty exists as to the fibula's contribution to resisting torsional loads. 18,25 Finally, our loading design does not account for all of the complexities seen in a tibia loaded by the femoral condyles and talus, nor by complex muscular interactions.…”

The relative position of the human fibula to the tibia influences cross‐sectional properties of the tibia

“…While both bones share loading, and thus work together to resist the loads encountered in habitual activity, our results support this argument, further suggesting that the tibia and fibula also compensate for one another. As reviewed in the Introduction, researchers (e.g., Thambyah and Pereira, ; Cristofolini et al, ) have argued that the fibula mitigates some of the loads that the tibia would otherwise have experienced. Our results indicate that this is the case only for the anatomical position of the fibula in cross‐section; tibial minimum bending rigidity increases as the fibula is located more posteriorly.…”

“…Additionally, the fibula may provide substantial load reduction for the tibia. In particular, torsional forces from the femur on the tibia may be mitigated by the fibula (Thambyah and Pereira, ), partly as a result of anteroposterior movement of the fibular head during internal and external rotation of the lower limb (Scott et al, ). Although the femur and tibia have one to two magnitudes greater stiffness than the fibula, stiffness and strain distribution on the same plane among all three bones are similar when subjected to bending and torsion (Cristofolini, Schileo, Juszczyk, Taddei, Martelli, & Viceconti, ).…”

Role of the fibula in the stability of diaphyseal tibial fractures fixed by intramedullary nailing

“…In vitro studies have also demonstrated load transfer through the interosseous membrane, which connects the tibia and fibula (Skraba and Greenwald, 1984, Thomas et al, 1995, Vukicevic et al, 1980, Wang et al, 1996. In addition to its axial load-sharing role, the fibula has also been shown to contribute to the rotational stiffness of the lower leg (Thambyah and Pereira, 2006).…”