The proximal extent of the ankle capsule and safety for the insertion of percutaneous fine wires

Establishing a low-risk zone for a temporary extra-articular calcaneo-tibial pin fixation in an unstable ankle or subtalar joint

This study aimed to establish a low-risk zone to avoid neurovascular injury during a temporary extra-articular calcaneo-tibial pin fixation in an unstable ankle or subtalar joint. A line from the calcaneal tuberosity center to the lateral end of the posterior malleolus at the ankle joint level defines the lateral border of this zone. Another line from the calcaneal tuberosity center to the midpoint of the anterior distal tibial articular surface at the joint level defines its medial border. This region was assumed to have a low neurovascular injury risk upon pin insertion. Fifty ankles from 50 patients who had undergone magnetic resonance imaging (MRI) for ankle disorders were assessed. T1-weighted oblique axial MRI slices were oriented to the pin trajectory. The mean distances between the sural nerve and the lateral border of the low-risk zone and between the posterior tibial neurovascular structures and the medial border of the low-risk zone were 15.0 ± 2.5 (range 9.1 to 21.1) and 12.8 ± 2.6 (6.3 to 20.8) mm, respectively. No neurovascular structures were identified within the low-risk zone. These findings demonstrated that an unstable ankle or subtalar joint can be temporarily fixated with an extra-articular calcaneo-tibial pin at a defined zone with a low neurovascular injury risk.

Development of a Synovial Fistula Through a Screw Hole Following Supramalleolar Osteotomy Hardware Removal: A Case Report

A synovial fistula is the communication between the synovial space and the skin. In most cases, the fistula tract is located within the soft tissue; therefore, excision and closure of the fistula have been described as surgical treatment. Rarely, fistulas may form within the bone following procedures around the joint, such as core biopsy and bone tunneling for ligament reconstruction. In such cases, the insertion of materials filling the bone tunnel with cement or bone graft was introduced. This report describes a case of synovial fistula in the distal tibiofibular joint through a screw hole following the removal of supramalleolar osteotomy hardware. We present a novel technique to close the communication by inserting a larger sized screw as a plug.

Articular Cartilage of the Syndesmosis: Avoiding Iatrogenic Cartilage Injury During Syndesmotic Fixation

BACKGROUND

The optimal surgical management of syndesmosis injuries consists of internal fixation between the distal fibula and tibia. Much of the available data on this joint details the anatomy of the syndesmotic ligaments. Little is published evaluating the distribution of articular cartilage of the syndesmosis, which is of importance to minimize the risk of iatrogenic damage during surgical treatment. The purpose of this study is to describe the articular cartilage of the syndesmosis.

METHODS

Twenty cadaveric ankles were dissected to identify the cartilage of the syndesmosis. Digital images of the articular cartilage were taken and measured using calibrated digital imaging software.

RESULTS

On the tibial side, distinct articular cartilage extending above the plafond was identified in 19/20 (95%) specimens. The tibial cartilage extended a mean of 6 ± 3 (range, 2-13) mm above the plafond. On the fibular side, 6/20 (30%) specimens demonstrated cartilage proximal to the talar facet, which extended a mean of 24 ± 4 (range, 20-31) mm above the tip of the fibula. The superior extent of the syndesmotic recess was a mean of 10 ± 3 (range, 5-17) mm in height. In all specimens, the syndesmosis cartilage did not extend more than 13 mm proximal to the tibial plafond and the syndesmotic recess did not extend more than 17 mm proximal to the tibial plafond.

CONCLUSION

Syndesmosis fixation placed more than 13 mm proximal to the tibial plafond would have safely avoided the articular cartilage in all specimens and the synovial-lined syndesmotic recess in most.

CLINICAL RELEVANCE

This study details the articular anatomy of the distal tibiofibular joint and provides measurements that can guide implant placement during syndesmotic fixation to minimize the risk of iatrogenic cartilage damage.

Avoiding iatrogenic vascular injury in tibial external fixation with half pins. An in-vivo study based on CT angiography

BACKGROUND

External fixation is an important tool in the management of variety of tibial fractures. Appropriate half pin insertion is important, to provide stable fixation without compromising the surgical field for definitive surgical procedures, and avoiding further damage to the important structures of the traumatized limb. There is paucity of literature about the optimal trajectories and safe corridors for half pins insertion based on in vivo studies. The available studies are based on anatomic atlases, cadaveric studies or half pin related complications.The aim of the current study is to present the findings of CT angiograms, in patients with external fixation of tibia, to enhance our understanding of optimal trajectories in safe corridors for half pins insertion.

MATERIAL AND METHODS

We performed a retrospective study of patients with external fixators on the tibia, who had undergone CT angiogram as part of pre-operative planning for orthoplastic reconstructive procedures. The relationship between the tips of the fixator half pins and named vessels of the leg were analyzed, pins within 5 mm of a named vessel were considered to be a risk of causing iatrogenic injury.

RESULTS

A total 51 patients, with in situ temporizing external fixators, with 134 half pins in different segments of the tibia were analyzed. More than 5 mm of penetration beyond the far cortex was noted in 47%, while in another 16% of pins penetration was more than 10 mm beyond the cortex. A tip to vessel distance (TVD) of 5 mm or less was noted in 28/134 (21%) of the pins, which highlights potential risk to the neurovascular bundles of the leg.

CONCLUSION

Risk of iatrogenic injury to neurovascular structures from half pin insertion can be reduced by meticulous use of fluoroscopy, by avoiding penetration beyond the far cortex, and avoiding exiting with half pins on the lateral surface in the distal 1/3rd of segment II of tibia. Moreover observing optimal trajectories and safe corridors for pin insertion, and selection of appropriate type of half pin can mitigate the risk to these structures.

High-Energy Pilon Fractures: Role of External Fixation in Acute and Definitive Treatment. What are the Indications and Technique for Primary Ankle Arthrodesis?

External fixation is an essential tool in the management of high-energy pilon fractures. Reduction techniques using the external fixator and fixation constructs for use with external fixation as a part of stage management are reviewed. The concepts of external fixation with limited articular fixation is discussed. The use of circular external fixation in both acute management of high-energy pilon fractures, as well as the indications and technique for acute ankle arthrodesis as part of primary treatment of pilon fractures are outlined.

Anatomy of the ankle capsule: A cadaveric study

Although bony and ligamentous injuries of the ankle are well understood, little is known about the degree to which injury of the ankle capsule can be a component of such injuries. The purpose of this study was to determine the dimensions of the ankle capsule and its relationship to adjacent structures. Thirteen fresh-frozen ankle specimens were systematically dissected. Methylene blue solution was injected to identify the dimensions of the ankle capsule. External dimensions were measured as the distance from the capsular reflection to the bony margin of the ankle. Internal dimensions were measured as the distance from the capsular attachment of the distal tibia, fibula, and talus to the cartilage margin. The anterior aspect of the capsule demonstrated the most proximal capsular reflection in all specimens. The most proximal reflections of the anteromedial, anterior middle and anterolateral capsule were 10.3, 13.5, and 9.8 mm, respectively. The most proximal reflections of the posteromedial, posterior middle and posterolateral region were 8.7, 6.2, and 3.5 mm, respectively. There was no capsular reflection over the medial malleolus and less than 1 mm over the posterior lateral malleolus. There was a confluence of the capsule and ligamentous complex on the medial side, and also with the transverse tibiofibular ligament about the posterolateral ankle. The most proximal attachment of the ankle capsule was located at the anterior aspect of the distal tibia. The medial and posterolateral capsules were confluent with the ligamentous complexes of the ankle in those regions. Clin. Anat. 31:1018-1023, 2018. © 2018 Wiley Periodicals, Inc.

An Anatomical Study on the Safe Placement of Orthopedic Hardware for Syndesmosis Fixation

Articular cartilage and bony contact at the distal tibiofibular cartilage contact zone (TFCCZ) is variable. The appropriate placement of syndesmotic hardware would benefit from a more accurate characterization of the proximal extent of the TFCCZ allowing surgeons to place hardware that simultaneously improves biomechanical stability and decreases the risk of iatrogenic cartilage damage. In addition, Ilizarov wire fixation through the distal fibula and tibia can pass through the syndesmosis recess. Anatomically defining the proximal extent of this recess can help decrease the risk of inadvertent capsular penetration. This study anatomically defines the TFCCZ and syndesmosis recess establishing a safe and biomechanically advantageous distance from the plafond for orthopedic fixation. This study measured the height of the TFCCZ and the syndesmotic recess in 3158 anatomical and cadaveric specimens. A TFCCZ was present in 59% of the Robert J. Terry Anatomical Collection specimens. Maximal height of the TFCCZ averaged 5.7±1.7 mm (99% confidence interval [CI], 5.6-5.8 mm) for anatomical specimens and 5.6±1.6 mm (99% CI, 4.6-6.5 mm) for cadaveric dissections. The maximum TFCCZ height was 11.71 mm. Maximal height of the syndesmotic recess averaged 12.8±2.1 mm for anatomical specimens and 13.7±2.7 mm for cadaveric specimens. The "3 cm rule" appears to be appropriate for fine wire fixation accounting for capsular distension that can be associated with injuries but not applicable for syndesmotic fixation. There is a less than 0.1% chance of encountering the TFCCZ cartilage at 10.9 mm above the plafond and a less than 0.01% chance at 12 mm above the plafond. [Orthopedics. 2017; 40(2):e329-e333.].

Arthroscopic Anatomy of the Ankle Joint

There are a number of variations in the intra-articular anatomy of the ankle which should not be considered pathological under all circumstances. The anteromedial corner of the tibial plafond (between the anterior edge of the tibial plafond and the medial malleolus) can have a notch, void of cartilage and bone. This area can appear degenerative arthroscopically; it is actually a normal variant of the articular surface. The anterior inferior tibiofibular ligament (AITF) can possess a lower, accessory band which can impinge on the anterolateral edge of the talar dome. In some cases it can cause irritation along this area of the talus laterally. If it is creating local irritation it can be removed since it does not provide any additional stabilization to the syndesmosis. There is a beveled region at the anterior leading edge of the lateral and dorsal surfaces of the talus laterally. This triangular region is void of cartilage and subchondral bone. The lack of talar structure in this region allows the lower portion of the AITF ligament to move over the talus during end range dorsiflexion of the ankle, preventing impingement. The variation in talar anatomy for this area should not be considered pathological.

Incidence of Intracapsular Placement When Inserting Medial Talar Body Schanz Pins: An Anatomic Study

OBJECTIVES

Medial talar body pins may be inserted to provide points of fixation in the hindfoot when applying external fixators. Because of the proximity to the ankle joint, there is a risk of intracapsular pin placement. We hypothesized that intracapsular placement is common when inserting medial talar body pins.

METHODS

Medial talar body pins were inserted in 12 fresh frozen cadaver ankles. Arthrography of each ankle was then performed to determine whether the pin was intracapsular. Each pin was then removed, and fluoroscopy was repeated to evaluate for contrast extravasation from the pin insertion site. The distance from the apex of the talar head to the anterior extent of the ankle capsule was measured to determine a safe area for extracapsular pin placement.

RESULTS

Arthrograms of all 12 ankles demonstrated that the pins were intracapsular. After pin removal, there was contrast extravasation from the pin insertion site in all specimens. Contrast was present in the pin tract in all specimens. Mean distance from the talar head to the anterior ankle capsule was 20.95 ± 4.8 mm (range, 12.2-27.3 mm) on the lateral view and 15.5 ± 1.8 mm (range, 12.4-20.0 mm) on the anteroposterior view of the foot.

CONCLUSIONS

There is a high rate of intracapsular pin placement when inserting medial talar body pins. Pin placement within the joint capsule risks seeding a sterile joint with bacteria and fistula formation when the pin remains in place for prolonged periods. For this reason, talar body pins should be avoided in temporizing external fixation frames.

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

A syndesmosis is defined as a fibrous joint in which two adjacent bones are linked by a strong membrane or ligaments.This definition also applies for the distal tibiofibular syndesmosis, which is a syndesmotic joint formed by two bones and four ligaments. The distal tibia and fibula form the osseous part of the syndesmosis and are linked by the distal anterior tibiofibular ligament, the distal posterior tibiofibular ligament, the transverse ligament and the interosseous ligament. Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. In an estimated 1–11% of all ankle sprains, injury of the distal tibiofibular syndesmosis occurs. Forty percent of patients still have complaints of ankle instability 6 months after an ankle sprain. This could be due to widening of the ankle mortise as a result of increased length of the syndesmotic ligaments after acute ankle sprain. As widening of the ankle mortise by 1 mm decreases the contact area of the tibiotalar joint by 42%, this could lead to instability and hence early osteoarthritis of the tibiotalar joint. In fractures of the ankle, syndesmotic injury occurs in about 50% of type Weber B and in all of type Weber C fractures. However,in discussing syndesmotic injury, it seems the exact proximal and distal boundaries of the distal tibiofibular syndesmosis are not well defined. There is no clear statement in the Ashhurst and Bromer etiological, the Lauge-Hansen genetic or the Danis-Weber topographical fracture classification about the exact extent of the syndesmosis. This joint is also not clearly defined in anatomical textbooks, such as Lanz and Wachsmuth. Kelikian and Kelikian postulate that the distal tibiofibular joint begins at the level of origin of the tibiofibular ligaments from the tibia and ends where these ligaments insert into the fibular malleolus. As the syndesmosis of the ankle plays an important role in the stability of the talocrural joint, understanding of the exact anatomy of both the osseous and ligamentous structures is essential in interpreting plain radiographs, CT and MR images, in ankle arthroscopy and in therapeutic management. With this pictorial essay we try to fill the hiatus in anatomic knowledge and provide a detailed anatomic description of the syndesmotic bones with the incisura fibularis, the syndesmotic recess, synovial fold and tibiofibular contact zone and the four syndesmotic ligaments. Each section describes a separate syndesmotic structure, followed by its clinical relevance and discussion of remaining questions.

The ‘Retro-Fibular Wire’

Anatomical atlases document safe corridors for placement of wires when using fine-wire circular external fixation. The furthest posterolateral corridor described in the distal tibia is through the fibula. This limits the crossing angle and stability of the frame. In this paper we describe a new, safe Retro-Fibular Wire corridor, which provides greater crossing angles and increased stability. In a cadaver study, 20 formalin-treated legs were divided into two groups. Wires were inserted into the distal quarter of the tibia using two possible corridors and standard techniques of dissection identified the distance of the wires from neurovascular structures.

In both groups the posterior tibial neurovascular bundle was avoided. In group A the peroneal artery was at risk. In group B this injury was avoided. Comparison of the groups showed a significant difference (p < 0.001).

We recommend the Retro-Fibular wire technique whereby wires are inserted into the tibia mid-way between the posteromedial border of the fibula and the tendo Achillis, at 30° to 45° to the sagittal plane, and introduced from a posterolateral to an anteromedial position. Subsequently, when using this technique in 30 patients, we have had no neurovascular complications or problems relating to tethering of the peroneal tendons.