Anatomy of the distal tibiofibular syndesmosis in adults: a pictorial essay with a multimodality approach

Biomechanical comparison of bionic, screw and Endobutton fixation in the treatment of tibiofibular syndesmosis injuries

BACKGROUND

The two prevalent fixation methods in the treatment of syndesmosis injuries, the rigid screw fixation and flexible Endobutton fixation, are not without issues; thus, we have designed a novel bionic fixation method which combines the features of both rigid and flexible fixations. The aim of this study was to compare the biomechanical properties of the bionic fixation to the screw and Endobutton fixations.

METHODS

Six normal fresh-frozen legs from amputation surgery were used. After initial tests of intact syndesmosis, screw, bionic and Endobutton fixations were performed sequentially for each specimen. Axial loading as well as rotation torque were applied, in five different ankle positions: neutral position, dorsiflexion, plantar flexion, varus, and valgus. The displacement of the syndesmosis and the tibial strain were analysed using a biomechanical testing system.

RESULTS

Whether receiving axial loading or rotation torque, in most situations (neutral position, dorsiflexion, varus, plantar flexion with low loading, valgus with high loading, internal and external rotation), the bionic group and Endobutton group had comparable displacements, and there was no significant difference among the intact, bionic, and Endobutton groups; whereas the displacements of the screw group were smaller than any of the other three groups. Results of the tibial strain were similar with that of the displacement.

CONCLUSIONS

The bionic fixation at least equals the performance of Endobutton fixation; it also allows more physiologic movement of the syndesmosis when compared to the screw fixation and may serve as a viable option for the fixation of the tibiofibular syndesmosis.

Arthroscopic Arthrodesis of the Distal Tibiofibular Syndesmosis

Chronic syndesmosis disruption can occur if an acute lesion is missed or inadequately managed. This can result in significant functional deficit and development of post-traumatic ankle arthritis. Anatomic reduction of the syndesmosis and maintenance of the reduction by syndesmotic screw fixation alone, ligamentous reconstruction, or fusion of the syndesmosis are recommended. A technique of arthroscopic distal tibiofibular syndesmosis arthrodesis is described.

Fractures of the ankle joint: investigation and treatment options

BACKGROUND

Ankle fractures are common, with an incidence of up to 174 cases per 100 000 adults per year. Their correct classification and treatment are of decisive importance for clinical outcome.

METHOD

Selective review of the literature.

RESULTS

Ankle fractures are initially evaluated by physical examination and then by x-ray. They can be classified according to either the AO Foundation (Association for the Study of Internal Fixation) or the Weber classification. Dislocated fractures need emergency treatment with immediate reduction; this is crucial for the prevention of hypoperfusion and nerve damage. Weber A fractures can usually be treated conservatively, while Weber B and C fractures are usually treated with surgery. An evaluation of the stability of the syndesmosis is important for anatomical reconstruction of the joint. Wound hematoma and wound-edge necrosis are the most common complications, and the postoperative infection rate is 2%. Up to 10% of patients develop ankle arthrosis over the intermediate or long term.

CONCLUSION

With properly chosen treatment, a good clinical outcome can be achieved. The long-term objective is to prevent post-traumatic ankle arthrosis. The evidence level for optimal treatment strategies is low.

Histological analysis of the structural composition of ankle ligaments

BACKGROUND

Various ankle ligaments have different structural composition. The aim of this study was to analyze the morphological structure of ankle ligaments to further understand their function in ankle stability.

METHODS

One hundred forty ligaments from 10 fresh-frozen cadaver ankle joints were dissected: the calcaneofibular, anterior, and posterior talofibular ligaments; the inferior extensor retinaculum, the talocalcaneal oblique ligament, the canalis tarsi ligament; the deltoid ligament; and the anterior tibiofibular ligament. Hematoxylin-eosin and Elastica van Gieson stains were used for determination of tissue morphology.

RESULTS

Three different morphological compositions were identified: dense, mixed, and interlaced compositions. Densely packed ligaments, characterized by parallel bundles of collagen, were primarily seen in the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments. Ligaments with mixed tight and loose parallel bundles of collagenous connective tissue were mainly found in the inferior extensor retinaculum and talocalcaneal oblique ligament. Densely packed and fiber-rich interlacing collagen was primarily seen in the areas of ligament insertion into bone of the deltoid ligament.

CONCLUSIONS

Ligaments of the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments have tightly packed, parallel collagen bundles and thus can resist high tensile forces. The mixed tight and loose, parallel oriented collagenous connective tissue of the inferior extensor retinaculum and the talocalcaneal oblique ligament support the dynamic positioning of the foot on the ground. The interlacing collagen bundles seen at the insertion of the deltoid ligament suggest that these insertion areas are susceptible to tension in a multitude of directions.

CLINICAL RELEVANCE

The morphology and mechanical properties of ankle ligaments may provide an understanding of their response to the loads to which they are subjected.

Ankle syndesmosis: a qualitative and quantitative anatomic analysis

BACKGROUND

Syndesmosis sprains can contribute to chronic pain and instability, which are often indications for surgical intervention. The literature lacks sufficient objective data detailing the complex anatomy and localized osseous landmarks essential for current surgical techniques.

PURPOSE

To qualitatively and quantitatively analyze the anatomy of the 3 syndesmotic ligaments with respect to surgically identifiable bony landmarks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Sixteen ankle specimens were dissected to identify the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), interosseous tibiofibular ligament (ITFL), and bony anatomy. Ligament lengths, footprints, and orientations were measured in reference to bony landmarks by use of an anatomically based coordinate system and a 3-dimensional coordinate measuring device.

RESULTS

The syndesmotic ligaments were identified in all specimens. The pyramidal-shaped ITFL was the broadest, originating from the distal interosseous membrane expansion, extending distally, and terminating 9.3 mm (95% CI, 8.3-10.2 mm) proximal to the central plafond. The tibial cartilage extended 3.6 mm (95% CI, 2.8-4.4 mm) above the plafond, a subset of which articulated directly with the fibular cartilage located 5.2 mm (95% CI, 4.6-5.8 mm) posterior to the anterolateral corner of the tibial plafond. The primary AITFL band(s) originated from the tibia 9.3 mm (95% CI, 8.6-10.0 mm) superior and medial to the anterolateral corner of the tibial plafond and inserted on the fibula 30.5 mm (95% CI, 28.5-32.4 mm) proximal and anterior to the inferior tip of the lateral malleolus. Superficial fibers of the PITFL originated along the distolateral border of the posterolateral tubercle of the tibia 8.0 mm (95% CI, 7.5-8.4 mm) proximal and medial to the posterolateral corner of the plafond and inserted along the medial border of the peroneal groove 26.3 mm (95% CI, 24.5-28.1 mm) superior and posterior to the inferior tip of the lateral malleolus.

CONCLUSION

The qualitative and quantitative anatomy of the syndesmotic ligaments was reproducibly described and defined with respect to surgically identifiable bony prominences.

CLINICAL RELEVANCE

Data regarding anatomic attachment sites and distances to bony prominences can optimize current surgical fixation techniques, improve anatomic restoration, and reduce the risk of iatrogenic injury from malreduction or misplaced implants. Quantitative data also provide the consistency required for the development of anatomic reconstructions.

Radiographic assessment of posterior malleolar ankle fractures

The anatomy of the posterior tibial malleolus plays an important role in the structure and function of the ankle mortise. With specific respect to ankle fractures, the presence, size, and displacement of posterior malleolar fractures (Volkmann's fracture) helps determine which will be amendable to operative fixation. The objective of the present study was to increase the body of knowledge with respect to the ability of foot and ankle reconstructive surgeons to assess posterior malleolar ankle fractures using plain film radiography. Three different variables were investigated on Sawbones(®) models: (1) differing size of posterior malleolar fractures (10%, 25%, and 50% of the tibial plafond), (2) differing displacement of posterior malleolar fractures (0 and 5 mm of proximal displacement), and (3) 2 different radiographic projections (standard lateral and externally rotated lateral projections). Accurate identification of the posterior malleolar fracture occurred on 86.67% (26 of 30) of standard lateral radiographs and 100% (30 of 30) of externally rotated lateral radiographs. Furthermore, the surgeons described the fracture with greater precision and had greater interclass correlation coefficient values with respect to measurement of sagittal plane displacement (0.977 versus 0.939) and percentage of involvement of the tibial plafond (0.972 versus 0.775) with an externally rotated lateral projection compared with a standard lateral projection. Our results provide evidence that an externally rotated lateral radiographic projection can provide surgeons with some additional information with respect to the presence, size, and displacement of posterior malleolar ankle fractures.

CT characterizing the anatomy of uninjured ankle syndesmosis

Although it is expert opinion that transsyndesmotic screws are placed obliquely 30° from posterolateral to anteromedial in the transverse plane, this has not been formally studied, and there is inconsistency regarding the congruency of the distal tibiofibular joint. Thirty-eight computed tomography (CT) scans of the lower extremity were used to examine the rotational profile of the axis of the syndesmotic joint in relation to the femoral transepicondylar axis and to describe the congruency of this joint. The axis of the distal tibiofibular joint was 32°±6° externally rotated in relation to the transepicondylar axis. The average anterior, central, and posterior widths of the syndesmotic joint space 10 mm superior to the joint line were statistically significantly different: 1.7±0.9 mm, 1.7±0.6 mm, and 2.3±1.1 mm, respectively (P=.004). This study demonstrates that the axis of the uninjured distal tibiofibular joint is approximately 30° externally rotated in relation to the transepicondylar axis. Therefore, reduction clamps and screws should be placed at this angle to avoid malreduction of the syndesmosis. The posterior joint space width is significantly wider than the anterior and central joint spaces. This study's results provide a description of the anatomy of the uninjured distal tibiofibular joint to guide reduction maneuvers and establish a baseline for evaluation of postreduction CT scans.

Isolated posterior high ankle sprain: a report of three cases

High ankle sprains are difficult to diagnose and account for 10% of all ankle sprains. A high index of suspicion is essential for diagnosis. High ankle sprains are managed symptomatically, with prolonged rehabilitation. The posterior inferior tibiofibular ligament is the strongest syndesmotic ligament; isolated injury of it is rare. We present 3 cases of isolated posterior high ankle sprain and discuss the relevant anatomy, mechanism of injury, and management.

Syndesmosis injuries

Traumatic injuries to the distal tibiofibular syndesmosis commonly result from high-energy ankle injuries. They can occur as isolated ligamentous injuries and can be associated with ankle fractures. Syndesmotic injuries can create a diagnostic and therapeutic challenge for musculoskeletal physicians. Recent literature has added considerably to the body of knowledge pertaining to injury mechanics and treatment outcomes, but there remain a number of controversies regarding diagnostic tests, implants, techniques, and postoperative protocols. Use of the novel suture button device has increased in recent years and shows some promise in clinical and cadaveric studies. This article contains a review of syndesmosis injuries, including anatomy and biomechanics, diagnosis, classification, and treatment options.

Post-traumatic heterotopic ossification of distal tibiofibular syndesmosis mimicking a surface osteosarcoma

AIM

To present the imaging features of post-traumatic heterotopic ossification (HO) of the distal tibiofibular syndesmosis initially suspected to be a surface osteosarcoma.

MATERIALS AND METHODS

A retrospective review was conducted of the presenting complaint and imaging features of patients with a final diagnosis of HO referred over an 8 year period to a specialist orthopaedic oncology centre.

RESULTS

Five patients with HO were identified. All were adult males with an age range of 19-41 years. There was a history of prior ankle trauma in all cases but the significance was not recognized at the time of referral to the specialist centre. There was radiographic evidence of HO arising from the inner aspects of the distal tibia and fibula approximately 3 cm proximal to the ankle joint. The HO was "kissing" in two cases and partially fused (synostosis) in two. The HO in the fifth case was arising on the inner fibular cortex alone. Magnetic resonance imaging (MRI), available in four cases, showed predominantly low signal intensity due to the dense bone formation.

CONCLUSION

The history of prior ankle trauma with ossification arising from the inner aspects of both the distal tibia and fibula is typical of post-traumatic HO and distinguish this benign condition from the rare surface osteosarcoma at this site.

Pure closed posteromedial dislocation of the tibiotalar joint without fracture

Pure tibiotalar dislocation without an associated fracture is an extremely rare injury. We present three cases of closed posteromedial tibiotalar dislocation without any associated fractures to the foot, ankle, or leg. All patients were treated conservatively with immediate closed reduction under general or local anaesthesia and immobilised in a short leg cast for six weeks without weight-bearing resulting in a satisfactory outcome at the final follow-up. A review of the literature is also presented in this paper.

[Evidence for treatment of acute syndesmosis injuries in sports]

Injuries of the distal syndesmosis often accompany acute ankle sprains especially in professional team sports. While small partial syndesmosis lesions can often be missed as a consequence of impressive symptoms due to ventrolateral capsuloligamentous injuries, higher grade injuries of the syndesmosis can mostly be diagnosed without any problem. Furthermore, there is a consensus concerning the necessity of operative treatment in significantly unstable situations as well concerning conservative treatment of incomplete partial lesions. Consequently, the greatest challenge regarding diagnostic tools, quantification and optimal therapy arises in the most common form of sport-associated, complete or partial lesions of the distal syndesmosis. This review article summarizes sports-associated injuries of the distal tibiofibular syndesmosis considering the current literature and placing the emphasis on the anatomy, pathobiomechanics, diagnostics and therapy of syndesmosis lesions from an evidence-based viewpoint.

A technical complication of radiosynovectomy in the ankle: leakage to distal tibiofibular syndesmosis

Chronic hemophilic synovitis due to intra-articular bleeding in hemophilia A (a congenital coagulation defect) is a common manifestation. Radiosynovectomy is used for the ablation of chronic hemophilic synovitis. Complications due to radiosynovectomy may be seen, such as leakage of radioactivity to the lymph nodes, liver, and spleen via the lymphatic system. We report herein 2 cases that developed leakage to the distal tibiofibular syndesmosis, lymph nodes, liver, and spleen after radiosynovectomy to the ankles. In order to prevent leakage, low-volume injection is recommended.

Distal tibiofibular radiological overlap: Does it always exist?

OBJECTIVES

Overlap between the distal tibia and fibula has always been quoted to be positive. If the value is not positive then an injury to the syndesmosis is thought to exist. Our null hypothesis is that it is a normal variant in the adult population.

METHODS

We looked at axial CT scans of the ankle in 325 patients for the presence of overlap between the distal tibia and fibula. Where we thought this was possible we reconstructed the images to represent a plain film radiograph which we were able to rotate and view in multiple planes to confirm the assessment.

RESULTS

The scans were taken for reasons other than pathology of the ankle. We found there was no overlap in four patients. These patients were then questioned about previous injury, trauma, surgery or pain, in order to exclude underlying pathology.

CONCLUSION

We concluded that no overlap between the tibia and fibula may exist in the population, albeit in a very small proportion.

Tibiofibular syndesmosis in acute ankle fractures: additional value of an oblique MR image plane

OBJECTIVE

To evaluate the additional value of a 45° oblique MRI scan plane for assessing the anterior and posterior distal tibiofibular syndesmotic ligaments in patients with an acute ankle fracture.

MATERIALS AND METHODS

Prospectively, data were collected for 44 consecutive patients with an acute ankle fracture who underwent a radiograph (AP, lateral, and mortise view) as well as an MRI in both the standard three orthogonal planes and in an additional 45° oblique plane. The fractures on the radiographs were classified according to Lauge-Hansen (LH). The anterior (ATIFL) and posterior (PTIFL) distal tibiofibular ligaments, as well as the presence of a bony avulsion in both the axial and oblique planes was evaluated on MRI. MRI findings regarding syndesmotic injury in the axial and oblique planes were compared to syndesmotic injury predicted by LH. Kappa and the agreement score were calculated to determine the interobserver agreement. The Wilcoxon signed rank test and McNemar's test were used to compare the two scan planes.

RESULTS

The interobserver agreement (κ) and agreement score [AS (%)] regarding injury of the ATIFL and PTIFL and the presence of a fibular or tibial avulsion fracture were good to excellent in both the axial and oblique image planes (κ 0.61-0.92, AS 84-95%). For both ligaments the oblique image plane indicated significantly less injury than the axial plane (p < 0.001). There was no significant difference in detection of an avulsion fracture in the axial or oblique plane, neither anteriorly (p = 0.50) nor posteriorly (p = 1.00). With syndesmotic injury as predicted by LH as comparison, the specificity in the oblique MR plane increased for both anterior (to 86% from 7%) and posterior (to 86% from 48%) syndesmotic injury when compared to the axial plane.

CONCLUSION

Our results show the additional value of an 45° oblique MR image plane for detection of injury of the anterior and posterior distal tibiofibular syndesmoses in acute ankle fractures. Findings of syndesmotic injury in the oblique MRI plane were closer to the diagnosis as assumed by the Lauge-Hansen classification than in the axial plane. With more accurate information, the surgeon can better decide when to stabilize syndesmotic injury in acute ankle fractures.

Correlation between radiological assessment of acute ankle fractures and syndesmotic injury on MRI

OBJECTIVE

Owing to the shortcomings of clinical examination and radiographs, injury to the syndesmotic ligaments is often misdiagnosed. When there is no indication requiring that the fractured ankle be operated on, the syndesmosis is not tested intra-operatively, and rupture of this ligamentous complex may be missed. Subsequently the patient is not treated properly leading to chronic complaints such as instability, pain, and swelling. We evaluated three fracture classification methods and radiographic measurements with respect to syndesmotic injury.

MATERIALS AND METHODS

Prospectively the radiographs of 51 consecutive ankle fractures were classified according to Weber, AO-Müller, and Lauge-Hansen. Both the fracture type and additional measurements of the tibiofibular clear space (TFCS), tibiofibular overlap (TFO), medial clear space (MCS), and superior clear space (SCS) were used to assess syndesmotic injury. MRI, as standard of reference, was performed to evaluate the integrity of the distal tibiofibular syndesmosis. The sensitivity and specificity for detection of syndesmotic injury with radiography were compared to MRI.

RESULTS

The Weber and AO-Müller fracture classification system, in combination with additional measurements, detected syndesmotic injury with a sensitivity of 47% and a specificity of 100%, and Lauge-Hansen with both a sensitivity and a specificity of 92%. TFCS and TFO did not correlate with syndesmotic injury, and a widened MCS did not correlate with deltoid ligament injury.

CONCLUSION

Syndesmotic injury as predicted by the Lauge-Hansen fracture classification correlated well with MRI findings. With MRI the extent of syndesmotic injury and therefore fracture stage can be assessed more accurately compared to radiographs.