Distal Fibula Reconstruction in Primary Malignant Tumours

(1) Background: Restoration of ankle biomechanics after distal fibula (DF) resection in bone sarcomas can be performed with different techniques. We report the functional and oncological outcomes of a case series; (2) Methods: Ten patients (5 females and 5 males) with a mean age of 27 years (range 10–71) were retrospectively evaluated. Following the resection, different techniques were used to reconstruct the ankle: tibiotalar arthrodesis, residual lateral malleolus fixed to the tibia, non-vascularized or rotational vascularized fibula transposition and intercalary allograft. All complications were recorded, and the functional outcomes were evaluated; (3) Results: The mean follow-up time was 54 months (range, 13–116). Six patients were free of disease while four patients died of disease. All patients had a stable ankle and bone union, which was achieved after a mean of 9.4 months (range 3–20). The mean MSTS Score was 26.7 (range 21–30). Chronic ankle pain and peroneal external nerve palsy were observed. Patients underwent additional surgeries for deep infection and for equinus ankle deformity. No local recurrence was observed. Metastasis occurred in four patients after a mean of 14.7 months (range 2–34); (4) Conclusions: After DF resection, the restoration of ankle biomechanics gives acceptable functional results, but a larger series of patients with long-time follow-up are required to confirm the durability of the reconstruction.

Biomechanics of the Distal Tibiofibular Syndesmosis: A Systematic Review of Cadaveric Studies

Background: This investigation’s purpose was to perform a systematic review of the literature examining the biomechanics of the ligaments comprising the distal tibiofibular syndesmosis with specific attention to their resistance to translational and rotational forces. Although current syndesmosis repair techniques can achieve an anatomic reduction, they may not reapproximate native ankle biomechanics, resulting in loss of reduction, joint overconstraint, or lack of external rotation resistance. Armed with a contemporary understanding of individual ligament biomechanics, future operative strategies can target key stabilizing structure(s), translating to a repair better equipped to resist anatomic displacing forces. Study design: Systematic review. Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Biomechanical studies testing cadaveric lower limb specimens in the intact and injured state measuring the distal tibiofibular syndesmosis resistance to translational and rotational forces were included in this review. Only studies that included numerical data were included in this review; studies that only reported figures and graphs were excluded. Results: Twelve studies met the inclusion and exclusion criteria. Two studies determined the mechanical properties of syndesmotic ligaments, finding superior strength and stiffness of the interosseous ligament (IOL), as compared to the anterior (AITFL) or posteroinferior tibiofibular ligament (PITFL). Four studies examined native ankle biomechanics establishing physiologic range of motion of the fibula relative to the tibia. Fibular range of motion was found to be up to 2.53 mm of posterior translation (Markolf et al), 1.00 mm lateral translation (Xenos et al), 3.6 degrees of external rotation (Burssens et al), and 1.4 degrees of internal rotation (Clanton et al). Four studies evaluated syndesmotic biomechanics under physiological loading and found that the AITFL, IOL, and PITFL provide the majority of resistance to external rotation, diastasis, and internal rotation, respectively. Two studies investigated the biomechanics of clinically and intraoperatively used tests for syndesmotic injuries and found increased sensitivity of sagittal plane posterior fibular translation, as opposed to coronal plane lateral fibular translation for unstable injuries. Conclusions: Study findings suggest that although the IOL is the strongest syndesmotic ligament, the AITFL has a dominant role stabilizing the distal tibiofibular syndesmosis to external rotation force. Because of these characteristics, operative repair of the AITFL along its native vector may provide a more biomechanically advantageous construct and should be investigated clinically. Additionally, evaluation of clinical stress tests revealed that the external rotation stress test is the most sensitive test to recognize an AITFL tear, and that a 3-ligament disruption is needed to cause diastasis greater than 2 mm.

Effect of Football Shoe Collar Type on Ankle Biomechanics and Dynamic Stability during Anterior and Lateral Single-Leg Jump Landings

In this study, we investigated the effects of football shoes with different collar heights on ankle biomechanics and dynamic postural stability. Fifteen healthy college football players performed anterior and lateral single-leg jump landings when wearing high collar, elastic collar, or low collar football shoes. The kinematics of lower limbs and ground reaction forces were collected by simultaneously using a stereo-photogrammetric system with markers (Vicon) and a force plate (Kistler). During the anterior single-leg jump landing, a high collar shoe resulted in a significantly smaller ankle dorsiflexion range of motion (ROM), compared to both elastic (p = 0.031, dz = 0.511) and low collar (p = 0.043, dz = 0.446) types, while also presenting lower total ankle sagittal ROM, compared to the low collar type (p = 0.023, dz = 0.756). Ankle joint stiffness was significantly greater for the high collar, compared to the elastic collar (p = 0.003, dz = 0.629) and low collar (p = 0.030, dz = 1.040). Medial-lateral stability was significantly improved with the high collar, compared to the low collar (p = 0.001, dz = 1.232). During the lateral single-leg jump landing, ankle inversion ROM (p = 0.028, dz = 0.615) and total ankle frontal ROM (p = 0.019, dz = 0.873) were significantly smaller for the high collar, compared to the elastic collar. The high collar also resulted in a significantly smaller total ankle sagittal ROM, compared to the low collar (p = 0.001, dz = 0.634). Therefore, the high collar shoe should be effective in decreasing the amount of ROM and increasing the dynamic stability, leading to high ankle joint stiffness due to differences in design and material characteristics of the collar types.

Ankle Joint Pressure Change in Varus Malalignment of the Tibia

Background : Varus malalignment of the tibia could alter ankle biomechanics, and might lead to degenerative changes of the ankle joint. However, previous studies failed to report the detailed changes of ankle biomechanics in varus malalignment of the tibia. The aim of this biomechanical study was to evaluate how the ankle joint pressure would change in response to the incremental increases in varus malalignment of the tibia. Methods 8 fresh-frozen human cadaver legs were tested in this study. Varus malalignment of the tibia and a total of 600N compressive force was simulated using a custom made fixture. Intra-articular sensors (TeckScan) were inserted in the ankle joint to collect the ankle joint pressure data. The testing sequence was 0°, 2°,4°,6°,8°,10°,12°,14°,16°,18°,20° of tibial varus. Results As the tibial varus progressed, the center of force (COF) shifted laterally both for the medial and lateral aspect of the ankle joint. For the medial aspect of the ankle joint, the lateral shift reached its maximum at 8º [2.76 (1.62) mm, p=0.002] of tibial varus, while for the lateral aspect of the ankle joint, the lateral shift reached its maximum at 12º [2.11 (1.19) mm, p=0.002] of tibial varus. Thereafter, the COF shifted medially as the tibial varus progressed. For the lateral aspect of the ankle joint, The P mean increased from 2103.8 (625.1) kPa at 0º to 2295.3 (589.7) kPa at 8º of tibial varus (p=0.047) , significant difference was found between the P mean at 0º and 8º (p=0.047) of tibial varus. Then as the tibial varus progressed, the P mean decreased to 1748.9 (467.2) kPa at 20º of tibial varus (p=0.002) . The lateral joint pressure ratio also increased from 0.481 (0.125) at 0º to 0.548 (0.108) at 10º of tibial varus (p=0.002) , then decreased to 0.517 (0.101) at 20º of tibial varus (p=0.002) . Conclusions For mild tibial varus deformities, there was a lateral shift of COF and lateral stress concentration within the ankle joint. However, as the tibial varus progressed, the COF shifted medially and the lateral stress concentration decreased.

Ankle Joint Pressure Change in Varus Malalignment of the Tibia

Background: Varus malalignment of the tibia could alter ankle biomechanics, and might lead to degenerative changes of the ankle joint. However, previous studies failed to report the detailed changes of ankle biomechanics in varus malalignment of the tibia. The aim of this biomechanical study was to evaluate how the ankle joint pressure would change in response to the incremental increases in varus malalignment of the tibia. Methods 8 fresh-frozen human cadaver legs were tested in this study. Varus malalignment of the tibia and a total of 600N compressive force was simulated using a custom made fixture. Intra-articular sensors (TeckScan) were inserted in the ankle joint to collect the ankle joint pressure data. The testing sequence was 0°, 2°,4°,6°,8°,10°,12°,14°,16°,18°,20° of tibial varus. Results As the tibial varus progressed, the center of force (COF) shifted laterally both for the medial and lateral aspect of the ankle joint. For the medial aspect of the ankle joint, the lateral shift reached its maximum at 8º [2.76 (1.62) mm, p=0.002] of tibial varus, while for the lateral aspect of the ankle joint, the lateral shift reached its maximum at 12º [2.11 (1.19) mm, p=0.002] of tibial varus. Thereafter, the COF shifted medially as the tibial varus progressed. For the lateral aspect of the ankle joint, The Pmean increased from 2103.8 (625.1) kPa at 0º to 2295.3 (589.7) kPa at 8º of tibial varus (p=0.047) , significant difference was found between the Pmean at 0º and 8º (p=0.047) of tibial varus. Then as the tibial varus progressed, the Pmean decreased to 1748.9 (467.2) kPa at 20º of tibial varus (p=0.002) . The lateral joint pressure ratio also increased from 0.481 (0.125) at 0º to 0.548 (0.108) at 10º of tibial varus (p=0.002) , then decreased to 0.517 (0.101) at 20º of tibial varus (p=0.002) . Conclusions For mild tibial varus deformities, there was a lateral shift of COF and lateral stress concentration within the ankle joint. However, as the tibial varus progressed, the COF shifted medially and the lateral stress concentration decreased.

Ankle Joint Pressure Change in Varus Malalignment of Tibia

Background: Varus malalignment of tibia could alter ankle biomechanics, might lead to degenerative changes of the ankle joint. However, previous studies failed to report the detailed changes of ankle biomechanics in varus malalignment of tibia. The aim of this biomechanical study was to evaluate ankle joint pressure change in response to the gradual progression of varus malalignment of tibia. Methods 8 fresh-frozen human cadaver legs were tested in this study. Varus malalignment of tibia and a total of 600N compressive force was simulated using a custom made fixture. Intra-articular sensors(TeckScan)were inserted in the ankle joint to collected ankle joint pressure data. The testing sequence was 0°, 2°,4°,6°,8°,10°,12°,14°,16°,18°,20° of tibial varus. Results As the tibial varus progressed, the center of force(COF) shifted laterally both for medial and lateral aspect of the ankle joint. For medial aspect of ankle joint, the lateral shift reached its maximum at 6º[2.76(1.46)mm, p=0.001] and 8º[2.76(1.62)mm, p=0.002], while for lateral aspect of ankle joint, the lateral shift reached its maximum at 12º[2.11(1.19)mm, p=0.002], thereafter, the COF shifted medially as the tibial varus progressed. The lateral joint pressure ratio was 0.481(0.125) at 0º and 0.548(0.108) at 10º and 0.517(0.101) at 20º. Significant differences were found between 0º and 10º(p=0.002), 10º and 20º (p=0.002)of tibial varus. Conclusions For mild tibial varus deformities, there was a lateral shift of COF and lateral stress concentration within the ankle joint, while as the deformity progressed, COF shifted medially and lateral stress concentration decreased. Keywords: ankle biomechanics, tibial varus, joint pressure measurement