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

Comparison between Suture-Button Technique with Syndesmotic Repair and Screw Fixation Technique for Complete Ankle Syndesmotic Injury: Biomechanical Cadaveric Study

Background

The tibiofibular syndesmosis is essential for preserving the stability of the ankle. Acute syndesmotic injuries with evident or latent instability usually warrant surgical interventions. This cadaveric study examines and compares biomechanical characteristics between the following treatments for syndesmosis injuries: suture-button fixation plus syndesmotic repair and screw fixation.

Methods

The lower extremities of 10 cadavers disarticulated at the knee joints were used, yielding 20 feet. Ten feet underwent surgery using the suture-button fixation with syndesmotic repair, while the remaining 10 feet underwent surgery using screw fixation. Before surgical treatment of syndesmosis injuries, each cadaveric lower limb underwent preliminary physiological cyclic loading, which was followed by a series of postfixation cyclic loading tests after the surgical procedure.

Results

Our principal finding is that suture-button fixation with syndesmotic repair provided torsional strength comparable to that of screw fixation. The mean failure torque did not differ between the 2 groups, but the rotational stiffness was significantly lower in the suture-button fixation/augmentation group.

Conclusions

Suture-button fixation/augmentation facilitates flexible (physiological) syndesmosis movement and may be a useful alternative treatment for ankle syndesmosis injury.

Isolated syndesmotic injury: treatment with suture button system-retrospective cohort study

Background

Ankle injuries, often involving the syndesmotic complex, are common and may lead to acute instability. The syndesmosis, comprising several key ligaments, provides critical support for ankle function. This study assesses the efficacy and safety of the suture button system for isolated syndesmotic injuries, a treatment method that is gaining popularity over traditional transsyndesmotic screws.

Methods

A retrospective review was conducted on patients treated surgically with the suture button system for isolated syndesmotic injuries from January 2018 to December 2023. Key outcomes measured included time to full weight-bearing, returning of daily activities, and complications. The study also compared these outcomes with historical data from screw fixation methods.

Results

Thirty-two patients (20 men, 12 women; mean age 41.66 ± 16.57 years [range 16-72 years]) were analyzed over an average follow-up of 9.94 ± 5.49 months (range 3-28 months). Patients achieved full weight-bearing at 1.23 ± 0.31 months postoperatively, resumed daily activities with restrictions at 3 ± 1.09 months, and without restrictions at 6.67 ± 2.55 months. No major complications were reported; minor complications included implant removal due to irritation in two patients (6.25%) and minor wound issues in one patient (3.13%).

Conclusion

The suture button system demonstrated good outcomes in allowing physiological motion, low malreduction rates, and minimizing reoperation needs. The present results indicate a promising safety profile and functional recovery, despite limitations such as small sample size and lack of patient-reported outcome measures.

The tibiofibular mortise - anatomical controversies and their clinical importance: a historical and pictorial essay

INTRODUCTION

During 280 years of studies of the anatomy of the distal tibiofibular articulation, there have arisen many unclear issues regarding the description of individual structures and their terminology. These historical inaccuracies were subsequently reflected in the clinical practice.

MATERIALS AND METHODS

A literature search of original publications and historical sources was performed.

RESULTS

The distal tibiofibular articulation is a synovial joint, rather than a syndesmosis, as it is an integral part of the ankle joint. The interosseous tibiofibular ligament (ITFL), described for the first time by a French anatomist Bichat in 1801, is the strongest ligament of the tibiofibular mortise. Unfortunately, this clinically important ligament is not recognized by the current international anatomical nomenclature. The terms anterior inferior (AITFL) and posterior inferior tibiofibular ligaments (PITFL) are historical remnants "reimported" from the American/British literature and should not be used, because the analogous superior ligaments do not exist. The intermalleolar ligament, first described by Weitbrecht in 1742, is a variable, but constant, structure reinforcing the posterior capsule of the ankle joint. The term inferior transverse ligament (IFT) denoting in the English literature the inferior part of the posterior tibiofibular ligament was originally used for the intermalleolar ligament. The IFT ligament is a part of the posterior tibiofibular ligament and there is no reason to stress its importance.

CONCLUSION

The chaos in the anatomy, terminology and depiction of the articulation of the distal tibia and fibula, unparalleled in any other joint of the human body, is the result of historical development. A certain negative role was, in this respect, played also by Basiliensia Nomina Anatomica (1895), that eradicated ITFL and called the distal tibiofibular joint a syndesmosis.

Ligamentous Injuries in Stable Ankle Fractures: An MRI-Based Study

Background

Ankle fractures are common orthopaedic injuries, and their management is primarily determined by fracture stability. The Lauge-Hansen classification system categorizes fractures according to mechanism of injury and ligaments involved. Supination external rotation (SER) type 2 fractures correspond to stable weber B fractures and are traditionally treated nonoperatively, whereas SER 3 and SER 4 fractures, characterized by syndesmosis disruption, typically require surgical intervention. We hypothesize that some apparently stable injuries may involve additional structures, challenging the conventional treatment approach. This study aims to determine the prevalence of SER 3 and SER 4 ankle injuries among radiographically stable SER 2 fractures.

Method

The study used baseline data from a longitudinal cohort conducted at Gold Coast Hospital and Health Service (GCHHS). Patients attending the GCHHS fracture clinic with radiographically stable SER 2 fractures were invited to participate. Those meeting the eligibility criteria underwent ankle magnetic resonance imaging (MRI) to evaluate the integrity of syndesmotic and ankle ligaments.

Results

Fifty-six participants were recruited, 38 (68%) female and 18 (32%) male, with a mean age of 47.2 years. All had stable syndesmoses on radiographic assessment and diagnosed with stable SER 2 ankle fractures. MRI scans revealed that 71% (n = 40) met the criteria for SER 2 injuries, 25% (n = 14) for SER 3 injuries with complete ruptures of posterior inferior tibiofibular ligament (PITFL), and 4% (n = 2) for SER 4 injuries with PITFL and deltoid ligament (DL) ruptures. These results challenge the assumption that radiographically stable SER 2 fractures are consistently stable in terms of additional structures involved.

Conclusion

The study highlights that a considerable proportion of seemingly stable ankle fractures involve more structures than previously thought. This suggests the management of SER 3 and SER 4 injuries could include nonoperative treatment.

Level of Evidence

Level III, cohort study.

Kinematic effects of unilateral TKA on the contralateral knee in Chinese patients with advanced osteoarthritis: a prospective gait analysis study

Background

Patients with knee osteoarthritis (OA) who receive unilateral total knee arthroplasty (TKA) often report reduced pain and enhanced function in the untreated knee, yet the kinematic mechanisms are not fully understood. Our study aimed to clarify these effects through a gait analysis of the untreated knee following unilateral TKA.

Methods

This study enrolled 118 end-stage OA patients with varus deformity scheduled for TKA, categorized into the contralateral osteoarthritis group (Contra-OA), consisting of patients with end-stage OA in both knees requiring surgical treatment, and the contralateral TKA group (Contra-TKA), which included patients who had undergone TKA on one knee and had end-stage OA in the untreated knee awaiting surgery. Kinematic data of the knee joint during treadmill walking were collected using the Opti_Knee gait analysis system, and a comparative analysis was conducted.

Results

The Contra-TKA group exhibited improvements in step length, anterior-posterior translation, range of motion, vertical translation, and internal-external rotation compared to the Contra-OA group (p-values ranging from 0.0013 to 0.0463). Notable differences in flexion-extension angles and abduction/adduction rotation were also observed (p = 0.0013 and 0.0166, respectively). At the initial contact (IC), obvious differences in internal-external rotation, anterior/posterior translation, and vertical translation were noted. At the opposite toe-off (OT), significant differences in internal-external rotation. At the tibia vertical (TV) moment, significant differences were observed in all three translation indicators of joint translation. At other pivotal gait cycle points, vertical and anterior/posterior translations in Contra-TKA group continued to exhibit more meaningful decrease. Collectively, these findings underscore the protective kinematic effects of TKA on the untreated contralateral knee, indicating an improved biomechanical adaptation following TKA surgery.

Conclusion

In summary, the study's findings indicate that unilateral TKA imparts kinetic effects on the untreated contralateral knee, as evidenced by significant improvements in key gait parameters. These enhancements, observed at both initial contacts and throughout the gait cycle, suggest a positive biomechanical support post-TKA, might contribute to better gait efficiency and reduced load on the contralateral untreated knee.

Standardized analysis of syndesmosis stability in ankle trauma with an innovative syndesmosis-test-tool: a biomechanical study

When treating ankle fractures, the question of syndesmosis complex involvement often arises. So far, there is no standardized method to reliably detect syndesmosis injuries in the surgical treatment of ankle fractures. For this reason, an intraoperative syndesmosis-test-tool (STT) was developed and compared to the recommended and established hook-test (HT). Tests were performed on cadaveric lower legs (n = 20) and the diastasis was visualized by 3D camera. Tests were performed at 50, 80, and 100 N in native conditions and four instability levels. Instability was induced from anterior to posterior and the reverse on the opposite side. The impact on diastasis regarding the direction, the force level, the instability level, and the device used was checked using a general linear model for repeated measurement. The direction of the induced instability showed no influence on the diastasis during the stability tests. The diastasis measured with the STT increased from 0.5 to 3.0 mm depending on the instability, while the range was lower with the HT (1.1 to 2.3 mm). The results showed that the differentiation between the instability levels was statistically significantly better for the developed STT. The last level of maximum instability was significantly better differentiable with the STT compared to the HT. An average visualizable diastasis of more than 2 mm could only be achieved at maximum instability. In conclusion, the newly developed STT was superior to the commonly used HT to detect instability.

Pediatric Maisonneuve and Tillaux Fractures with Lateral Ankle Dislocation: A Pediatric "Logsplitter" Injury: A Case Report

CASE

A 12-year-old adolescent boy presented with a proximal fibula fracture and lateral ankle dislocation consistent with a Maisonneuve fracture (MF) associated with a transsyndesmotic ankle dislocation. The dislocation was reduced under conscious sedation in the emergency department. Postreduction imaging studies demonstrated a Tillaux fracture. The patient underwent surgical stabilization of the Tillaux fragment and of the distal tibiofibular syndesmosis. At the 26-month follow-up, the patient remained active without restrictions.

CONCLUSION

Operative treatment of a concurrent MF, Tillaux fracture with lateral ankle dislocation, or a pediatric "logsplitter" injury resulted in satisfactory alignment and function of the ankle joint.

Current concepts in ankle fractures

Ankle fractures are among the most common orthopaedic injuries. Operative management is performed in unstable ankle fracture patterns to restore the stability and native kinematics of the ankle mortise and minimize the risk of post-traumatic degenerative changes. In this study, we review current concepts in ankle fracture management, including posterior malleolus fixation, syndesmosis fixation, deltoid ligament repair, fibular nailing, and early weightbearing, from both a biomechanical and clinical perspective.

Objective Assessment of Syndesmosis Stability Using the Hook Test

The hook test is a widely used intraoperative method for assessing syndesmosis stability. However, there are no recommendations regarding the force required to perform this test. Furthermore, the reliability of the test is unclear. Ten experienced surgeons performed hook tests on a cadaver bone model. The applied forces were recorded in a blinded manner. In addition, standardized hook tests with defined forces (50, 80, and 100 N) were performed on 10 pairs of cadaver lower legs and the syndesmosis was sequentially destabilized. Diastasis of the syndesmosis was recorded using an optical 3D camera system. A median force of 81 N (Range: 50 N-145 N) was applied. A proportion of 82% of the tests showed a force < 100 N. The data showed good intraraterreliability and poor interraterreliability. In the standardized investigation of the hook test on the cadaver bone model, both the force and the instability of the syndesmosis had a significant influence on the syndesmosis diastasis. Nevertheless, even with maximum instability of the syndesmosis, diastasis > 2 mm could only be measured in 12 of the 19 evaluable specimens. The widely used hook test shows a high variability when performed in practice. Even in a standardized manner, the hook test cannot detect a relevant syndesmosis injury.

Anatomy of the Ankle and Subtalar Joint Ligaments: What We Do Not Know About It?

Understanding of the ankle and subtalar joint ligaments is essential to recognize and manage foot and ankle disorders. The stability of both joints relies on the integrity of its ligaments. The ankle joint is stabilized by the lateral and medial ligamentous complexes while the subtalar joint is stabilized by its extrinsic and intrinsic ligaments. Most injuries to these ligaments are linked with ankle sprains. Inversion or eversion mechanics affect the ligamentous complexes. A profound knowledge of the ligament's anatomy allows orthopedic surgeons to further understand anatomic or nonanatomic reconstructions.

Instability of the distal tibiofibular syndesmosis

The distal tibiofibular syndesmosis (DTFS) is more frequently injured than previously thought. Early diagnosis and appropriate treatment is essential to avoid long term complications like chronic instability, early osteoarthritis and residual pain. Management of these injuries require a complete understanding of the anatomy of DTFS, and the role played by the ligaments stabilizing the DTFS and ankle. High index of suspicion, appreciating the areas of focal tenderness and utilizing the provocative maneuvers help in early diagnosis. In pure ligamentous injuries radiographs with stress of weight bearing help to detect subtle instability. If these images are inconclusive, then further imaging with MRI, CT scan, stress examination under anesthesia, and arthroscopic examination facilitate diagnosis. An injury to syndesmosis frequently accompanies rotational fractures and all ankle fractures need to be stressed intra-operatively under fluoroscopy after fixation of the osseous components to detect syndesmotic instability. Non-operative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. Anatomic reduction of the syndesmosis is critical, and currently both trans-syndesmotic screws and suture button fixation are commonly used for syndesmotic stabilization. Chronic syndesmotic instability (CSI) requires debridement of syndesmosis, restoration of ankle mortise with or without syndesmotic stabilization. Arthrodesis of ankle is used a last resort in the presence of significant ankle arthritis. This article reviews anatomy and biomechanics of the syndesmosis, the mechanism of pure ligamentous injury and injury associated with ankle fractures, clinical, radiological and arthroscopic diagnosis and surgical treatment.

Biomechanical Sequelae of Syndesmosis Injury and Repair

This review characterizes fibula mechanics in the context of syndesmosis injury and repair. Through detailed understanding of fibula kinematics (the study of motion) and kinetics (the study of forces that cause motion), the full complexity of fibula motion can be appreciated. Although the magnitudes of fibula rotation and translation are inherently small, even slight alterations of fibula position or movement can substantially impact force propagation through the ankle and hindfoot joints. Accordingly, implications for clinical care are discussed.