Anatomy of the proximal tibiofibular joint and interosseous membrane, and their contributions to joint kinematics in below‐knee amputations

Abstract

A result of below-knee amputations (BKAs) is abnormal motion that occurs about the proximal tibiofibular joint (PTFJ). While it is known that joint morphology may play a role in joint kinematics, this is not well understood with respect to the PTFJ. Therefore, the purposes of this study were: (i) to characterize the anatomy of the PTFJ and statistically analyze the relationships within the joint; and (ii) to determine the relationships between the PTFJ characteristics and the degree of movement of the fibula in BKAs. The PTFJ was characterized in 40 embalmed specimens disarticulated at the knee, and amputated through the mid-tibia and fibula. Four metrics were measured: inclination angle (angle at which the fibula articulates with the tibia); tibial and fibular articular surface areas; articular surface concavity and shape. The specimens were mechanically tested by applying a load through the biceps femoris tendon, and the degree of motion about the tibiofibular joint was measured. Regression analyses were performed to determine the relationships between the different PTFJ characteristics and the magnitude of fibular abduction. Finally, Pearson correlation analyses were performed on inclination angle and surface area vs. fibular kinematics. The inclination angle measured on the fibula was significantly greater than that measured on the tibia. This difference may be attributed to differences in concavity of the tibial and fibular surfaces. Surface area measured on the tibia and fibula was not statistically different. The inclination angle was not statistically correlated to surface area. However, when correlating fibular kinematics in BKAs, inclination angle was positively correlated to the degree of fibular abduction, whereas surface area was negatively correlated. The characteristics of the PTFJ dictate the amount of fibular movement, specifically, fibular abduction in BKAs. Predicting BKA complications based on PTFJ characteristics can lead to recommendations in treatment.

The morphology of proximal tibiofibular joint (PTFJ) predicts incident radiographic osteoarthritis: data from Osteoarthritis Initiative

“…This force is mainly transmitted through the PTFJ 25 that is located in the posterolateral corner of the tibia, and characterized by its great morphological variability. The morphological parameters of PTFJ includes: inclination angle, tibial and fibular articular surface areas, articular surface concavity and shape 26 . Scott et al 27 investigated the relationship between tibiofemoral varus loading and PTFJ motion on four human cadaveric knee specimens, and found that knee varus-valgus loading and the motion of PTFJ were affected by PTFJ geometry, suggesting that quantification of articular surface orientation should be considered in knee alignment.…”

Concurrent Surgical Management of Advanced Osteoarthritis of the Knee and Proximal Tibiofibular Joint With Compressive Peroneal Neuropathy: 3-Year Follow-Up On a Complex Case

“…Furthermore, alignment of the PTFJ has been classified into two anatomic variants, which can be distinguished by the obliquity of the joint surface relative to the horizontal plane [ 7 ]: “horizontal” if less than or equal to 20° joint inclination and “oblique” if greater than 20° of joint inclination, although intermediate varieties have been described as well [ 8 , 9 ]. This joint inclination influences the fibular rotation, which facilitates dorsiflexion and plantarflexion of the ankle [ 10 ]. The oblique joint inclination results in a smaller articular surface than the horizontal inclination, and Ogden reported a higher incidence of pathology such as subluxation and OA with the oblique inclination [ 7 ].…”

A novel method for assessing proximal tibiofibular joint on MR images in patients with knee osteoarthritis

“…PTFJ morphology was measured previously but inconsistent findings were reported. Several studies reported that the PTFJ surface area measured on the tibia and fibula was not statistically different 5,18 ; in contrast, Eichenblat and Nathan 4 reported that fibular articular surface areas were greater than tibial surface areas. The PTFJ inclination angle measured on the fibula was significantly greater than that measured on the tibia 18 .…”

“…Several studies reported that the PTFJ surface area measured on the tibia and fibula was not statistically different 5,18 ; in contrast, Eichenblat and Nathan 4 reported that fibular articular surface areas were greater than tibial surface areas. The PTFJ inclination angle measured on the fibula was significantly greater than that measured on the tibia 18 . In our current study, we measured the inclination angles between fibula surface and horizontal plane from both coronal and sagittal MR images to calculate mean PTFJ fibular surface area which was 2.4 cm 2 (SD: ±0.7 cm 2 ).…”