Influence of the interosseous talocalcaneal ligament injury on stability of the ankle-subtalar joint complex--a cadaveric experimental study

An ex vivo sequential ligament transection model of flatfoot

BACKGROUND

The ligaments implicated in the earliest stages of developing a progressive collapsing foot deformity are poorly understood. Commonly employed cadaveric flatfoot models are created from simultaneous transection of multiple ligaments, making it difficult to assess early changes in pressure distribution from ligaments critical for maintaining load distribution. A serial transection of ligaments may provide insight into changes in pressure distribution under the foot to identify a potential combination of ligaments that may be involved in early deformities.

METHODS

Specimens were loaded using a custom designed axial and tendon loading system. Plantar pressure data for the forefoot and hindfoot were recorded before and after six sequential ligament complex transections.

FINDINGS

Sectioning the plantar fascia (first) and short/long plantar ligaments (second) failed to generate appreciable differences in load distribution. Dividing the spring ligament (third) led to changes in hindfoot load distribution with a shift towards the lateral column indicative of hindfoot valgus angulation. All subsequent conditions resulted in similar patterns in hindfoot plantar load distribution. An anterior shift in the center of pressure only occurred after transection of all six ligament complexes.

INTERPRETATION

Loss of the plantar fascia and short/long plantar ligaments are not critical in maintaining plantar load distribution or contact area. However, the additional loss of the spring ligament caused notable changes in hindfoot load distribution, indicating the combination of these three ligament complexes is particularly critical for preventing peritalar subluxation. Minimal changes in load distribution occurred when performing additional transections to reach a complete flatfoot deformity.

Reconstruction of the interosseous talocalcaneal ligament using allograft for subtalar joint stabilization is effective

PURPOSE

The aim of this study was to assess the biomechanical effects of subtalar ligament injury and reconstruction on stability of the subtalar joint in all three spatial planes.

METHODS

Fifteen fresh frozen cadaveric legs were used, with transfixed tibiotalar joints to isolate motion to the subtalar joint. An arthrometer fixed to the lateral aspect of the calcaneus measured angular displacement in all three spatial planes on the inversion and eversion stress tests. Stress manoeuvres were tested with the intact joint, and then repeated after sequentially sectioning the inferior extensor retinaculum (IER), cervical ligament (CL), interosseous talocalcaneal ligament (ITCL), arthroscopic graft reconstruction of the ITCL, and sectioning of the calcaneo-fibular ligament (CFL).

RESULTS

Sectioning the ITCL significantly increased angular displacement upon inversion and eversion in the coronal and sagittal planes. Reconstruction of the ITCL significantly improved angular stability against eversion in the axial and sagittal planes, and against inversion in the axial and coronal planes, at the zero time point after reconstruction. After sectioning the CFL, resistance to eversion decreased significantly in all three planes.

CONCLUSION

Progressive injury of ligamentous stabilisers, particularly the ITCL, led to increasing angular displacement of the subtalar joint measured with the inversion and eversion stress tests, used in clinical practice. Reconstruction of the ITCL using tendon graft significantly stabilised the subtalar joint in the axial and sagittal planes against eversion and in the axial and coronal planes against inversion, immediately after surgery.

Evaluation of the heel external rotation test in soft tissue deficiencies associated with adult acquired flatfoot deformity (AAFD). A cadaver sectioning analysis

BACKGROUND

To date, evaluation of the heel external rotation test has not been taken with respect to AAFD. Traditional 'gold standard' tests do not account for the contribution of the midfoot ligaments towards instability. These tests would be flawed as any midfoot instability may produce a false positive result.

AIMS

To evaluate the differential contribution of the spring, deltoid and other local ligaments in external rotation generated at the heel.

METHODS

Serial ligament sectioning was performed on 16 cadaveric specimens, with a 40 N-external rotation force applied to the heel. These were divided into four groups with different sequences of ligament sectioning. Measurements of the total amount/range of external, tibiotalar and subtalar rotation were made.

RESULTS

The deep component of the deltoid ligament (DD) was the main ligament influencing heel external rotation (P < 0.05, in all cases), and acted primarily at the tibiotalar joint (87.9 %). The spring ligament (SL) influenced heel external rotation predominantly (91.2 %) at the subtalar joint (STJ). Greater than 20 degrees external rotation could only be achieved with DD sectioning. The interosseous (IO) and cervical (CL) ligaments did not significantly contribute to external rotation at either joint (P > 0.05).

CONCLUSION

Clinically relevant external rotation (>20 degrees) is solely attributable to DD failure in the presence of intact lateral ligaments (LL). This test may improve detection of DD instability and allow clinicians to subclassify patients with Stage 2 AAFD into those where DD may or may not be compromised.

Relationship between Joint and Ligament Structures of the Subtalar Joint and Degeneration of the Subtalar Articular Facet

This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angles were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Additionally, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.

Combined weightbearing CT and MRI assessment of flexible progressive collapsing foot deformity

BACKGROUND

The objective of this study was to evaluate the correlation between Weightbearing CT (WBCT) markers of pronounced peritalar subluxation (PTS) and MRI findings of soft tissue insufficiency in patients with flexible Progressive Collapsing Foot Deformity (PCFD). We hypothesized that significant correlation would be found.

METHODS

Retrospective comparative study with 54 flexible PCFD patients. WBCT and MRI variables deformity severity were evaluated, including markers of pronounced PTS, as well as soft tissue degeneration. A multiple regression analysis and partition prediction models were used to evaluate the relationship between bone alignment and soft tissue injury. P-values of less than .05 were considered significant.

RESULTS

Degeneration of the posterior tibial tendon was significantly associated with sinus tarsi impingement (p = .04). Spring ligament degeneration correlated to subtalar joint subluxation (p = .04). Talocalcaneal interosseous ligament involvement was the only one to significantly correlate to the presence of subfibular impingement (p = .02).

CONCLUSION

Our results demonstrated that WBCT markers of pronounced deformity and PTS were significantly correlated to MRI involvement of the PTT and other important restraints such as the spring and talocalcaneal interosseus ligaments.

LEVEL OF EVIDENCE

Level III, Retrospective comparative study.

A mouse model of ankle-subtalar joint complex instability induced post-traumatic osteoarthritis

BACKGROUND

Ankle-subtalar joint complex instability is not uncommonly presented in the clinic, but symptoms and signs similar to other conditions can easily lead to its misdiagnosis. Due to the lack of appropriate animal models, research on ankle-subtalar joint complex instability is limited. The aims of the present study were to establish an animal model of ankle-subtalar joint complex instability in mice and to explore its relationship with post-traumatic osteoarthritis (PTOA).

METHODS

Twenty-one male C57BL/6J mice were randomly divided into three groups: SHAM group (sham surgery group), transected cervical ligament + anterior talofibular ligament (CL+ATFL) group, and transected cervical ligament + deltoid ligament (CL+DL) group. Two weeks after surgery, all mice underwent cage running training. Balance beam and gait tests were used to evaluate the changes in self-movement in the mice after ankle-subtalar ligament injury. Micro-CT and histological staining were used to evaluate the progress of PTOA.

RESULTS

Compared with the SHAM group, balance and gait were affected in the ligament transection group. Twelve weeks after surgery, the time required to cross the balance beam in the CL+ATFL group was 35.1% longer and the mice slipped 3.6-fold more often than before surgery, and the mean step length on the right side was 7.2% smaller than that in the SHAM group. The time required to cross the balance beam in the CL+DL group was 32.1% longer and the mice slipped 3-fold more often than prior to surgery, and the average step length on the right side was 5.6% smaller than that in the SHAM group. CT images indicated that 28.6% of the mice in the CL+DL group displayed dislocation of the talus. Tissue staining suggested that articular cartilage degeneration occurred in mice with ligament transection 12 weeks after surgery.

CONCLUSIONS

Transected mice in the CL+ATFL and CL+DL groups displayed mechanical instability of the ankle-subtalar joint complex, and some mice in the CL+DL group also suffered from talus dislocation due to ligament injury leading to loss of stability of the bone structure. In addition, as time progressed, the articular cartilage displayed degenerative changes, which affected the ability of animals to move normally.

Imaging of Peritalar Instability

Undiagnosed medial ankle instability can be a prerequisite for pathogenic progression in the foot, particularly for adult acquired flatfoot deformity. With the complex anatomy in this region, and the limitations of each individual investigational method, accurately identifying peritalar instability remains a serious challenge to clinicians. Performing a thorough clinical examination aided by evaluation with advanced imaging can improve the threshold of detection for this condition and allow early proper treatment to prevent further manifestations of the instability.

Treatment of closed subtalar joint dislocation: A case report and literature review

Subtalar dislocation is defined as a separation of the talocalcaneal and talonavicular articulations, commonly caused by high-energy mechanisms, which include falls from height, motor vehicle crashes, and twisting leg injuries. The dislocations are divided into medial, lateral, anterior, and posterior types on the basis of the direction in which the distal part of the foot has shifted in relation to the talus. The most common type is medial dislocation resulted from inversion injury. Subtalar dislocation may accompany with other fractures. Physical examination must be performed carefully to assess for neurovascular compromise. Most of the subtalar dislocations can be treated with closed reduction under sedation. If this is not possible, open reduction without further delay should be conducted. After primary treatment, X-ray and computed tomography scan should be performed to evaluate the alignment and the fractures. We report a 37-year-old male patient sustained a subtalar dislocation without any bony injury when he was playing football. The patient was successfully treated by closed reduction, and a good alignment was observed at the last follow-up. The pathogenesis and treatment method of this case were analyzed, and the related literature were reviewed, which provided a reference for future clinical treatment.

Anatomic Arthroscopic Graft Reconstruction of the Interosseous Talocalcaneal Ligament for Subtalar Instability

Instabilities of the subtalar joint are commonly overlooked or mismanaged, and chronic instability is a debilitating condition leading to premature joint degeneration. Several methods of treatment have been described, mainly screw fixation, arthrodesis, or ligament reconstruction. Most studies describe open methods for ligament reconstruction. We describe an original technique for "all-inside" arthroscopic graft reconstruction of the interosseous talocalcaneal ligament for subtalar instability.

Biomechanical comparison of tenodesis reconstruction for subtalar instability: a finite element analysis

Background

There are several types of tenodesis reconstruction designed for subtalar instability. However, no comprehensive comparison has been conducted among these procedures in terms of their correcting power so far. The objective of this study is to evaluate the biomechanical behaviors of 5 representative procedures through finite element analysis.

Methods

Finite element models were established and validated based on one of our previous studies. The Pisani interosseous talocalcaneal ligament (ITCL) reconstruction, Schon cervical ligament (CL) reconstruction and Choisne calcaneofibular ligament (CFL) reconstruction were compared on the model with the CFL, ITCL and CL sectioned. The Schon triligamentous reconstruction and Mann triligamentous reconstruction were compared on the model with the CFL, ITCL and CL, as well as the ATFL sectioned. The inversion and external/internal rotation were quantified at different ankle positions based on the rotational moment. Then, the stress in ligaments and reconstructed grafts and the contact characteristics of the subtalar joint under inversional stress test were calculated and compared accordingly.

Results

For single ligament reconstruction, the Choisne CFL reconstruction provided the greatest degree of correction for subtalar instability, followed by the Schon CL reconstruction and then the Pisani ITCL reconstruction. For triligamentous reconstruction, the Mann procedure outperformed the Schon procedure in alleviating the subtalar instability.

Conclusion

The finite element analysis showed that the Choisne CFL reconstruction and Mann triligamentous reconstruction provided the greatest degree of immediate postoperative subtalar stability. However, both procedures could not restore the biomechanical behaviors of the subtalar joint to normal. The long-term efficacy of these procedures warrants further investigation using a substantially larger sample of clinical cases.

Surgical Treatment of Subtalar Joint Instability: Safety and Accuracy of a New Technique in a Cadaver Model

New surgical strategies to treat symptomatic subtalar joint (STJ) instability are evolving. We modified a previously described reconstruction strategy and then refined our new surgical technique through simulated surgery and subsequent cadaver dissections. Our purpose was to show that a tunnel intended to facilitate STJ stabilization surgery could safely be drilled across the footprints of the interosseous talocalcaneal ligament (ITCL). A percutaneous fluoroscopically guided tunnel for the purpose of ITCL reconstruction was created in 10 cadaveric below-knee specimens. Accuracy of the tunnel with relation to the anatomic boundaries of the ITCL attachment sites as well as damage to relevant structures at risk were recorded. Two sets of 5 surgeries were performed to assess for improvement in technique. Mean distances from the tunnel to the ITCL on the calcaneus improved between groups 1 and 2: 4.04 and 1.80 mm, respectively (p = .04). Mean distances from the tunnel to the ITCL on the talus improved between groups 1 and 2: 6.2 and 1.8 mm, respectively (p = .08). With information obtained from this study, an osseous tunnel can be safely placed within 2 mm of the ITCL footprints.

The Ankle-Joint Complex: A Kinesiologic Approach to Lateral Ankle Sprains

Copious research exists regarding ankle instability, yet lateral ankle sprains (LASs) persist in being among the most common recurrent musculoskeletal injuries. Key anatomical structures of the ankle include a triform articulating structure that includes the inferior tibiofibular, talocrural, and subtalar joints. Functionally, force absorption and propulsion through the ankle complex are necessary for any task that occurs in weight bearing. For optimal ankle performance and avoidance of injury, an intricate balance between stability and mobility is necessary to ensure that appropriate force transfer occurs during sports and activities of daily living. Consideration for the many structures that may be directly or indirectly involved in LASs will likely translate into advancements in clinical care. In this clinical review, we present the structure, function, and relevant pathologic states of the ankle complex to stimulate a better understanding of the prevention, evaluation, and treatment of LASs.

The dimensions of the tarsal sinus and canal in different foot positions and its clinical implications

This study presents a reference for the dimensions of the tarsal sinus and canal in healthy adults in different foot positions to facilitate understanding of the kinematics of the subtalar joint, the effect of an implant, and other clinical issues. In a 3D CT stress test on 20 subjects, the right foot was forced into a neutral and eight different extreme foot positions while CT scans were obtained. The bones were segmented in the neutral foot position. The kinematics of the bones in the extreme positions were determined relative to the neutral position. The dimensions of the tarsal sinus and canal were calculated by determining the radii of the maximal inscribed spheres at 20 equidistant locations along an axis in 3D surface models of the tali and calcanei in each foot position. The radii were small on the medial side and increased laterally. Medial from the middle, the radii were small and not significantly different among the various foot positions. At the lateral side, the dimensions were affected mainly by eversion or inversion and less by dorsiflexion or plantarflexion. The pattern was reproducible among subjects, but there were between-subject differences. The dimensions are mostly determined by rotation in the frontal plane. A pivot point was found medial from the middle. These data serve as a reference and model for predicting the effect of sinus implants and understanding such clinical problems as sinus tarsi syndrome. Between-subjects differences have to be taken into account. Clin. Anat. 30:1049-1057, 2017. © 2017 Wiley Periodicals, Inc.

Systematic Quantification of Stabilizing Effects of Subtalar Joint Soft-Tissue Constraints in a Novel Cadaveric Model

BACKGROUND

Distinguishing between ankle instability and subtalar joint instability is challenging because the contributions of the subtalar joint's soft-tissue constraints are poorly understood. This study quantified the effects on joint stability of systematic sectioning of these constraints followed by application of torsional and drawer loads simulating a manual clinical examination.

METHODS

Subtalar joint motion in response to carefully controlled inversion, eversion, internal rotation, and external rotation moments and multidirectional drawer forces was quantified in fresh-frozen cadaver limbs. Sequential measurements were obtained under axial load approximating a non-weight-bearing clinical setting with the foot in neutral, 10° of dorsiflexion, and 10° and 20° of plantar flexion. The contributions of the components of the inferior extensor retinaculum were documented after incremental sectioning. The calcaneofibular, cervical, and interosseous talocalcaneal ligaments were then sectioned sequentially, in two different orders, to produce five different ligament-insufficiency scenarios.

RESULTS

Incremental detachment of the components of the inferior extensor retinaculum had no effect on subtalar motion independent of foot position. Regardless of the subsequent ligament-sectioning order, significant motion increases relative to the intact condition occurred only after transection of the calcaneofibular ligament. Sectioning of this ligament produced increased inversion and external rotation, which was most evident with the foot dorsiflexed.

CONCLUSIONS

Calcaneofibular ligament disruption results in increases in subtalar inversion and external rotation that might be detectable during a manual examination. Insufficiency of other subtalar joint constraints may result in motion increases that are too subtle to be perceptible.

CLINICAL RELEVANCE

If calcaneofibular ligament insufficiency is established, its reconstruction or repair should receive priority over that of other ankle or subtalar periarticular soft-tissue structures.

Effects of insoles contact on static balance

[Purpose] This study examined the effect of the degree of the contact area between the insoles and soles on static balance. [Subjects and Methods] Thirteen healthy male and female adults voluntarily participated. All of the subjects wore three different types of insoles (no orthotic insole, partial contact, full contact) in the present experiment. The subjects were instructed to place both feet parallel to each other and maintain static balance for 30 seconds. Center of pressure parameters (range, total distance, and mean velocity) were analyzed. [Results] The results show that the anteroposterior range and mediolateral (ML) total distance and velocity decreased when orthotic insoles with partial contact or full contact were used in comparison to when a flat insole (no orthotic insole) was used. Also, the ML range and total distance were lower with full contact than in the other two conditions. These results indicate that static balance improves as the degree of contact between the soles and insoles increases. [Conclusion] The results of this study suggests that using insoles with increased sole contact area would improve static balance ability.

Biomechanical Comparison of External Fixation and Compression Screws for Transverse Tarsal Joint Arthrodesis

BACKGROUND

Transverse tarsal joint arthrodesis is commonly performed in the operative treatment of hindfoot arthritis and acquired flatfoot deformity. While fixation is typically achieved using screws, failure to obtain and maintain joint compression sometimes occurs, potentially leading to nonunion. External fixation is an alternate method of achieving arthrodesis site compression and has the advantage of allowing postoperative compression adjustment when necessary. However, its performance relative to standard screw fixation has not been quantified in this application. We hypothesized that external fixation could provide transverse tarsal joint compression exceeding that possible with screw fixation.

METHODS

Transverse tarsal joint fixation was performed sequentially, first with a circular external fixator and then with compression screws, on 9 fresh-frozen cadaveric legs. The external fixator was attached in abutting rings fixed to the tibia and the hindfoot and a third anterior ring parallel to the hindfoot ring using transverse wires and half-pins in the tibial diaphysis, calcaneus, and metatarsals. Screw fixation comprised two 4.3 mm headless compression screws traversing the talonavicular joint and 1 across the calcaneocuboid joint. Compressive forces generated during incremental fixator foot ring displacement to 20 mm and incremental screw tightening were measured using a custom-fabricated instrumented miniature external fixator spanning the transverse tarsal joint.

RESULTS

The maximum compressive force generated by the external fixator averaged 186% of that produced by the screws (range, 104%-391%). Fixator compression surpassed that obtainable with screws at 12 mm of ring displacement and decreased when the tibial ring was detached. No correlation was found between bone density and the compressive force achievable by either fusion method.

CONCLUSION

The compression across the transverse tarsal joint that can be obtained with a circular external fixator including a tibial ring exceeds that which can be obtained with 3 headless compression screws. Screw and external fixator performance did not correlate with bone mineral density. This study supports the use of external fixation as an alternative method of generating compression to help stimulate fusion across the transverse tarsal joints.

CLINICAL RELEVANCE

The findings provide biomechanical evidence to support the use of external fixation as a viable option in transverse tarsal joint fusion cases in which screw fixation has failed or is anticipated to be inadequate due to suboptimal bone quality.

Subtalar instability

Subtalar instability is a common clinical entity. Clinicians should have a high index of suspicion of this diagnosis in patients who have been diagnosed with chronic lateral ankle instability but have failed standard management and have continued pain in the sinus tarsi. As with ankle instability, nonoperative management is the initial mainstay of treatment. Operative management includes ligamentous reconstruction of key lateral stabilizers of the subtalar joint. Future research on this subject should be focused at improving diagnosis and recognition of this entity.

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.

The effects of a semi-rigid ankle brace on a simulated isolated subtalar joint instability

Subtalar joint instability is hypothesized to occur after injuries to the calcaneofibular ligament (CFL) in isolation or in combination with the cervical and the talocalcaneal interosseous ligaments. A common treatment for hindfoot instability is the application of an ankle brace. However, the ability of an ankle brace to promote subtalar joint stability is not well established. We assessed the kinematics of the subtalar joint, ankle, and hindfoot in the presence of isolated subtalar instability, investigated the effect of bracing in a CFL deficient foot and with a total rupture of the intrinsic ligaments, and evaluated how maximum inversion range of motion is affected by the position of the ankle in the sagittal plane. Kinematics from nine cadaveric feet were collected with the foot placed in neutral, dorsiflexion, and plantar flexion. Motion was applied with and without a brace on an intact foot and after sequentially sectioning the CFL and the intrinsic ligaments. Isolated CFL sectioning increased ankle joint inversion, while sectioning the CFL and intrinsic ligaments affected subtalar joint stability. The brace limited inversion at the subtalar and ankle joints. Additionally, examining the foot in dorsiflexion reduced ankle and subtalar joint motion.

A mechanical jig for measuring ankle supination and pronation torque in vitro and in vivo

This study presents the design of a mechanical jig for evaluating the ankle joint torque on both cadaver and human ankles. Previous study showed that ankle sprain motion was a combination of plantarflexion and inversion. The device allows measurement of ankle supination and pronation torque with one simple axis in a single step motion. More importantly, the ankle orientation allows rotation starting from an anatomical position. Six cadaveric specimens and six human subjects were tested with simulated and voluntary rotation respectively. The presented mechanical jig makes possible the determination of supination torque for studying ankle sprain injury and the estimation of pronation torque for examining peroneal muscle response.

Total ankle replacement in ankle arthritis with varus talar deformity: pathophysiology, evaluation, and management principles

Varus malalignment of the ankle may be a misleading term. The isolated frontal plane deformity has been shown to be multiplanar in nature. Identifying this dominant feature of the condition and applying appropriate surgical principles to allow for complete correction of the deformity are critical to a successful outcome. The following 3 factors are key to an optimal surgical outcome from TAR with VMAA: (1) Obtaining a congruent ankle with sufficient ROM is a important before implantation of the arthroplasty prosthesis; (2) not all ankles are correctable; and (3) recognition both preoperatively and intraoperatively that a conversion of TAR to a fusion is sometimes the best course of action to achieve best results or patient satisfaction.

Subtalar instability: diagnosis and treatment

Subtalar instability is challenging to diagnose. It rarely follows a complete subtalar dislocation, an event more likely to result in subtalar pain, stiffness, and arthritis. By history, subtalar instability can be suggested by the patient’s feeling of ankle instability, easy “rolling over,” and a need to look at the ground constantly when walking. Clinical measures for inversion and eversion do not accurately reflect isolated subtalar motion, as soft tissue and other joint motion confound the examination. Stress radiographs have high false positive rates. Magnetic resonance imaging can show injured or disorganized ligaments suggestive of recurrent subtalar strain, but are not dynamic studies and cannot alone diagnose instability. Operative treatment, when elected, should focus on determining the source of the problem. Generally direct repair of the lateral ligaments is sufficient. Bony malalignment should always be considered especially in the setting when previous ligament reconstruction has failed.

The relation between geometry and function of the ankle joint complex: a biomechanical review

This review deals with the relation between the anatomy and function of the ankle joint complex. The questions addressed are how high do the forces in the ankle joint get, where can the joints go (range of motion) and where do they go during walking and running. Finally the role of the ligaments and the articular surfaces is discussed, i.e. how does it happen. The magnitude of the loads on the ankle joint complex are primarily determined by muscle activity and can be as high as four times the body weight during walking. For the maximal range of motion, plantar and dorsiflexion occurs in the talocrural joint and marginally at the subtalar joint. In-eversion takes place at both levels. The functional range of motion is well within the limits of the maximal range of motion. The ligaments do not contribute to the forces for the functional range of motion but determine the maximal range of motion together with the articular surfaces. The geometry of the articular surfaces primarily determines the kinematics. Clinical studies must include these anatomical aspects to better understand the mechanism of injury, recovery, and interventions. Models can elucidate the mechanism by which the anatomy relates to the function. The relation between the anatomy and mechanical properties of the joint structures and joint function should be considered for diagnosis and treatment of ankle joint pathology.

Subtalar instability: a biomechanical cadaver study

HYPOTHESIS

Subtalar instability is thought to be one of the possible causes for chronic functional instability of the foot and ankle. The purpose of this study was to determine the extent of ligament injury that is followed by subtalar instability and to depict consecutive pathologic joint motion.

METHODS

Twelve fresh human cadaver lower legs were investigated with respect to pathologic motion and mobility of the subtalar joint in a modified spinal column simulator after arthrodesis of the talocrural articulation and selective sectioning of the lateral ligaments of the subtalar joint. In order to simulate several injury mechanisms, ligaments were dissected starting anteriorly in group one (n = 6) and posteriorly in group two (n = 6).

RESULTS

Dissection of the bifurcate ligament in group one resulted in a significant increase in plantar- and dorsiflexion, dissection of the inferior extensor retinaculum resulted in a significant increase in eversion and inversion. Additional dissection of the lateral talocalcaneal ligament resulted in a significant increase in internal and external rotation. Dissection of the calcaneofibular ligament in group two was followed by significant kinematic changes regarding all degrees of motion in the subtalar joint.

CONCLUSIONS

The calcaneofibular ligament plays a key role in lateral stabilisation of the subtalar joint. Therefore, ligaments of the subtalar joint should be included in surgical repair.

Ankle and subtalar kinematics during dorsiflexion-plantarflexion activities

BACKGROUND

Understanding the effect of weightbearing on subtalar and ankle joint kinematics is critical for the diagnosis and treatment of foot disorders. However, dynamic in vivo kinematics of these joints are not well studied. The purpose of this study was to compare in vivo kinematics during nonweightbearing and weightbearing activities in healthy subjects.

METHODS

Seven healthy subjects with a mean age of 32 (range, 23 to 42) years were enrolled. Oblique lateral fluoroscopic images of nonweightbearing and weightbearing dorsiflexion-plantarflexion activities were recorded. Three dimensional subtalar, ankle, and ankle-subtalar joint complex kinematics were determined using 3D-2D model registration techniques with 3D bone models and single-plane fluoroscopy.

RESULTS

During the weightbearing activity from 20 degrees dorsiflexion to 15 degrees plantarflexion, the subtalar joint was significantly more everted, dorsiflexed, and abducted, and the calcaneus showed a significantly more posterior position, than during the nonweightbearing activity. The ankle joint was significantly more plantarflexed and adducted during the weightbearing activity than the nonweightbearing activity. The ankle-subtalar joint complex was significantly more everted, and the calcaneus showed significantly greater posterior position than the nonweightbearing activity.

CONCLUSION

These observations provide basic quantitative descriptions of weightbearing and nonweightbearing kinematics for healthy joints.

CLINICAL RELEVANCE

These data can serve as the basis for comparison with pathologic feet for both diagnostic and therapeutic purposes.

Diagnosis and management of the painful ankle/foot part 1: clinical anatomy and pathomechanics

Distinctive anatomical features can be witnessed in the ankle/foot complex, affording specific pathological conditions. Disorders of the ankle/foot complex are multifactoral and features in both the clinical anatomy and biomechanics contribute to the development of ankle/foot pain. The superior tibiofibular, distal tibiofibular, talocrural, subtalar, and midtarsal joint systems must all participate in function of the ankle/foot complex, as each biomechanically contributes to functional movements and clinical disorders witnessed in the lower extremity. A clinician's ability to effectively evaluate, diagnose, and treat the distal lower extremity is largely reliant upon a foundational understanding of the clinical anatomy and biomechanics of this complex complex. Thus, clinicians are encouraged to consider these distinctions when examining and diagnosing disorders of the ankle/foot.

Comparative results of conservative treatments for isolated anterior talofibular ligament (ATFL) injury and injury to both the ATFL and calcaneofibular ligament of the ankle as assessed by subtalar arthrography

BACKGROUND

There have been no reports describing the results of conservative treatment of acute lateral ligament injury of the ankle in detail in terms of the severity of the injury, and the results of conservative treatment for injury with severe instability are still controversial. The purpose of this study was to assess the results of nonoperative treatment of acute lateral ligament injury according to its severity.

METHODS

Fifty-five consecutive acute lateral ankle ligament injuries in 54 patients who were treated nonoperatively were followed up as a prospective study. Twenty-seven were male patients and 27 were female patients; the average age was 23.9 years (12-55 years). The patients were divided into two groups according to the extent of the ligament injury: patients with an isolated injury of the anterior talofibular ligament and those with combined injuries of the anterior talofibular ligament and the calcaneofibular ligament. In addition to the routine examinations for inversion ankle sprain, subtalar arthrography was mainly used to assess the condition of the calcaneofibular ligament. The arthrography was performed an average of 3.5 days after the injury (0-5 days).

RESULTS

Fifty-five ankles of patients who were treated nonoperatively according to the same protocol were included in this study, and were followed up for an average of 5.0 years (37-86 months). At the time of the final follow-up, 22 of 25 (88%) ankles with an isolated injury to the anterior talofibular ligament were asymptomatic; in contrast, only 9 of 30 (30%) ankles with combined injuries of the anterior talofibular and calcaneofibular ligament were asymptomatic. The average American Orthopaedic Foot and Ankle Society score of the isolated injuries was 97.8 points, in contrast to 92.4 points for the combined injuries.

CONCLUSIONS

The results of nonoperative treatment with 1 week immobilization followed by a functional brace were excellent in patients with an isolated injury of the anterior talofibular ligament, but were unsatisfactory in those with combined injuries of the anterior talofibular and calcaneofibular ligaments.

Anatomy of ligamentous structures in the tarsal sinus and canal

BACKGROUND

The descriptive morphology of the interosseous talocalcaneal ligament and other structures in the tarsal sinus and canal vary. An anatomical investigation of the ligamentous structures in the tarsal sinus and canal identified two distinct ligaments, the interosseous talocalcaneal ligament and the anterior capsular ligament, and three components of the medial root of the inferior extensor retinaculum.

METHODS

Forty embalmed cadaver feet were examined. After disarticulation of the ankle joint, the posterior half of the talus was removed. The length, width, and thickness of the two ligaments and the three components of the extensor retinaculum in the tarsal canal and sinus were measured with calipers. Anatomical variations were recorded.

RESULTS

The interosseous talocalcaneal ligament was band-like in 92.5% (38 of 40) of examined specimens, and the anterior capsular ligament was present in 95% (39 of 40) of specimens. The interosseous talocalcaneal ligament, the medial component of the inferior extensor retinaculum, and the talar component of the inferior extensor retinaculum had one or two distinct anatomical variations of morphology and attachments. The interosseous talocalcaneal ligament and the medial component of the extensor retinaculum formed a V shape in the tarsal sinus and canal.

CONCLUSION AND CLINICAL RELEVANCE

We demonstrated the morphology and dimensions of the ligaments and components of the extensor retinaculum in the tarsal sinus and canal. Precise anatomy of the structures in the tarsal sinus and canal will strengthen our understanding of their function in the motion or stabilization of the subtalar joint. There may be a functional link between the medial component of the inferior extensor retinaculum and the interosseous talocalcaneal ligament.

Sinus tarsi syndrome and subtalar joint instability

Sinus tarsi syndrome is a poorly understood term in the orthopedic world. It is thought of as a painful condition of the sinus tarsi that often responds to corticosteroid injection and is associated with a feeling of instability in the hindfoot. Despite references in the literature, there is no agreement on pathognomonic history, clinical tests, or imaging studies that could help in confirming the diagnosis or establishing the etiology. Some authors relate the clinical condition of sinus tarsi syndrome with instability of the subtalar joint.

The effect of ankle injury on subtalar motion

BACKGROUND

Injuries to the medial and lateral ankle ligaments have been implicated in subtalar joint instability. Lateral injury increased subtalar joint varus and anterior translation, while deltoid injury increased external rotation and valgus in studies using static, non-physiologic testing.

METHODS

The current study employed a physiologically accurate ankle model using phasic force-couples attached to the muscle-tendon units to reproduce ankle motion. Six-degree-of-freedom kinematics of the tibia, talus, and calcaneus were measured using a VICON motion analysis system under the following experimental conditions: 1) intact ligaments 2) complete lateral ligament injury with subsequent repair, 3) superficial deltoid injury with subsequent repair, and 4) deep deltoid injury without repair in eight harvested lower extremities. Statistical analysis was by repeated measures analyses of variance.

RESULTS

At heel-strike, the subtalar joint is in internal rotation, dorsiflexion, and varus. As the leg progresses to foot-flat, there is external rotation, plantarflexion, and valgus rotation. From foot-flat to heel-rise, there is little subtalar joint motion, while at toe-off, there is slight internal rotation, dorsiflexion, and varus rotation. The total rotations amounted to 9.0 degrees (SD 5.0 degrees) external rotation, 6.1 degrees (SD 2.5 degrees) plantarflexion, and 7.8 degrees (SD 5.5 degrees) valgus. Disruption of the superficial deltoid increased plantarflexion (p < .001) and valgus (p < .05). The additional lateral injury increased both external rotation (p < .001) and valgus (p < .02). Lateral injury alone had no significant effect on subtalar joint motion.

CONCLUSION

Unlike most previous reports, this study showed no significant influence of isolated lateral ankle injury on subtalar joint motion, probably because the current study examined subtalar joint motion under physiologic loading and motion rather than by static stress testing. This calls into question the relevance of static stress testing to the in situ function of the subtalar joint. The increased external rotation and valgus seen with deltoid injury in the current study is consistent with previous reports.

The role of the interosseous talocalcaneal ligament in subtalar joint stability

BACKGROUND

Injury of the interosseous talocalcaneal ligament (ITCL) has been recognized as a cause of subtalar instability, though lack of an accepted clinical test has limited the ability of clinicians to reliably make the diagnosis. Clinical effects of ITCL failure remain unclear because of insufficient understanding of the role of the ligament.

METHODS

Load-displacement characteristics of the subtalar joint were studied in six cadaver specimens using an axial distraction test and a transverse multi-direction drawer test. In all tests, cyclic loading (+/-60 N) was applied, and load-displacement responses were collected before and after sectioning of the ITCL. Two parameters were used to analyze the data: neutral-zone laxity as a measure of joint play, and flexibility as a measure of resistance to applied force.

RESULTS

In the axial distraction test, sectioning increased both neutral-zone laxity and flexibility (p =.01 and.02, respectively). In the transverse test, sectioning caused increase of both neutral-zone laxity and flexibility (p <.001, for each). Neutral-zone laxity increased most greatly along an axis defined roughly by the posterior aspect of the fibula and the central region of the medial malleolus. Flexibility increased most in the medial direction (p <.05, for each).

CONCLUSIONS

Results confirmed the role of the ITCL in maintaining apposition of the subtalar joint, as well as suggested its role in stabilizing the subtalar joint against drawer forces applied to the calcaneus from lateral to medial. The dominant direction of increased neutral-zone laxity described above suggests the optimal direction for detecting subtalar instability involved with ITCL injury.

CLINICAL RELEVANCE

ITCL failure may result in subtalar instability and should be examined with a drawer force along the preferential axis roughly from the posterior aspect of the fibula to the central region of the medial malleolus. Further clinical evaluation is required to determine whether ITCL failure is reliably detectable.

Subtalar joint instability: current clinical concepts

There has been extensive research and investigation into the subtalar joint (STJ), yet the biomechanics that relate to its anatomic function, especially instability after injury, are surrounded by controversy. With a mechanism of injury closely related to the classic inversion ankle sprain, chronic instability can result following trauma to the lateral ligamentous support network of either joint. Over the past decades there have been countless examples in the literature challenging the current standard of evaluation and treatment of the "subtalar sprain." New technologies have offered varied approaches to diagnostic capability, each with its own strengths and weaknesses, ranging from standard radiographs to CT and MRI. A review of the literature should aid in deciphering the controversy surrounding this aspect of podiatric medicine.

Diagnosis and Management of the Painful Ankle/Foot. Part 2: Examination, Interpretation, and Management

Diagnosis, interpretation, and subsequent management of ankle/foot pathology can be challenging to clinicians. A sensitive and specific physical examination is the strategy of choice for diagnosing selected ankle/foot injuries and additional diagnostic procedures, at considerable cost, may not provide additional information for clinical diagnosis and management. Because of a distal location in the sclerotome and the reduced convergence of afferent signals from this region to the dorsal horn of the spinal cord, pain reference patterns are low and the localization of symptoms is trustworthy. Effective management of the painful ankle/foot is closely linked to a tissue-specific clinical examination. The examination of the ankle/foot should include passive and resistive tests that provide information regarding movement limitations and pain provocation. Special tests can augment the findings from the examination, suggesting compromises in the structural and functional integrity of the ankle/foot complex. The weight bearing function of the ankle/foot compounds the clinician's diagnostic picture, as limits and pain provocation are frequently produced only when the patient attempts to function in weight bearing. As a consequence, clinicians should consider this feature by implementing numerous weightbearing components in the diagnosis and management of ankle/foot afflictions. Limits in passive motion can be classified as either capsular or non-capsular patterns. Conversely, patients can present with ankle/foot pain that demonstrates no limitation of motion. Bursitis, tendopathy, compression neuropathy, and instability can produce ankle/foot pain that is challenging to diagnose, especially when they are the consequence of functional weight bearing. Numerous non-surgical measures can be implemented in treating the painful ankle/foot, reserving surgical interventions for those patients who are resistant to conservative care.

Effect of arch supports on ankle-subtalar complex instability: a biomechanical experimental study

BACKGROUND

Subtalar instability, which may cause persistent symptoms after severe inversion ankle sprains, often involves failure of the interosseous talocalcaneal ligament (ITCL). While several clinicians have reported surgical treatment for this pathology, nonsurgical management policy has not been well considered. Previously, it was proposed that ITCL failure possibly causes looseness of the tarsal arch construction resulting in abnormal ankle-subtalar kinematics occurring with axial forces. In the current study the author hypothesized that arch-support insole functions to improve abnormal joint kinematics in ankle-subtalar complex instability.

METHODS

Five fresh-frozen cadaver lower extremities with simulated ankle-subtalar complex instability, which was created by combined sectioning of the anterior talofibular ligament (ATFL) and the ITCL, were subjected to a biomechanical experiment. Cyclic axial loading from 9.8 to 668 N was applied with a material testing machine, while three-dimensional angular displacements in both the ankle and subtalar joints were determined with electric goniometers. The specimens were tested before and after inserting an arch-support insole that supports the medial-longitudinal and transverse arches of the foot.

RESULTS

Inserting the insole decreased the maximum ankle internal rotation, from 3.3 degrees +/- 0.9 degrees to 2.3 degrees +/- 0.4 degrees (p = .028), while subtalar rotation was not significantly changed.

CONCLUSIONS

The medial longitudinal arch-support insole reduced abnormal ankle internal rotation created by combined sectioning of the ATFL and ITCL, likely due to improved arch configuration stability.