Influence of kinematic analysis methods on detecting ankle and subtalar joint instability

Static posture weightbearing joint angle differences in patients with varus ankle osteoarthritis

BACKGROUND

Advanced varus ankle osteoarthritis is a debilitating disease that can present with limited physical function, severe pain, and diminished quality of life. Weightbearing computed tomography enables submillimeter 3-dimensional visualization, computational analyses, and enhanced diagnoses in reporting complex degenerative changes more accurately.

RESEARCH QUESTION

This study set to compare static posture weightbearing joint angle differences in healthy and varus ankle osteoarthritis patients (compensated and non-compensated).

METHODS

Our retrospective assessment included 70 individuals, 44 of whom were diagnosed with advanced varus ankle osteoarthritis, and the remaining 26 were healthy participants to serve as controls. An automatic anatomic coordinate system was applied to each patient's 3-dimensional talus and calcaneus bone reconstructions from weightbearing computed tomography scans. Subtalar and midtarsal joint angles were calculated using Euler angles.

RESULTS

We report statistical differences between the healthy group and both advanced varus osteoarthritis groups for midtarsal inversion/eversion. Specifically, both osteoarthritis groups' midtarsal joints were more inverted and plantarflexed as compared to healthy participants. Compensated and non-compensated subtalar joints were statistically different with respect to inversion/eversion. Non-compensated ankles exhibited a similar mean to healthy ankles who were both less inverted than compensated ankles.

SIGNIFICANCE

Our study helps physicians to better understand underlying mechanisms of peritalar compensation in varus ankle osteoarthritis. Patients featuring hindfoot compensation on average had a greater subtalar joint angle indicating greater inversion than healthy and non-compensated patients.

Enhancing Post-Surgical Rehabilitation Outcomes in Patients with Chronic Ankle Instability: Impact of Subtalar Joint Axis Balance Exercises Following Arthroscopic Modified Broström Operation

Background and Objectives: This study aimed to evaluate the effects of subtalar joint axis-based balance exercises on the anterior talofibular ligament (ATFL) thickness, ankle strength, and ankle stability after an arthroscopic modified Broström operation (AMBO) for chronic ankle instability (CAI). Materials and Methods: The study included 47 patients diagnosed with CAI who underwent AMBO and were randomly divided into three groups: control (n = 11), general balance exercise (n = 17), and subtalar joint axis balance exercise (n = 19), regardless of the affected area. Participants in the exercise rehabilitation group performed exercises for 60 min twice a week for six weeks, starting six weeks after AMBO. ATFL thickness, ankle strength, and ankle dynamic stability were measured using musculoskeletal ultrasonography, Biodex, and Y-balance test, respectively, before and after treatment. Results: Compared with the remaining groups, the subtalar joint axis balance exercise group had reduced ATFL thickness (p = 0.000), improved ankle strength for eversion (p = 0.000) and inversion (p = 0.000), and enhanced ankle stability (p = 0.000). Conclusions: The study results suggest that subtalar joint axis-based balance exercises may contribute to the early recovery of the ankle joint after AMBO.

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.

Increased subtalar rotational motion in patients with symptomatic ankle instability under load and stress conditions

PURPOSE

Differentiating subtalar and ankle instability in the clinical setting is challenging. This study aims to analyze the rotational laxity of the subtalar joint bilaterally in patients with asymptomatic and symptomatic ankle instability under simulated load and stress-induced position of the subtalar joint.

METHODS

A case-control study was conducted using an adjustable load device (ALD). Patients with chronic ankle instability and healthy volunteers were included. Each subject underwent a CT scan under mechanical stress and simulated weight-bearing conditions, maintaining maximum eversion and inversion hindfoot positions. The images were obtained in a single model, allowing calculations of the motion vector as well as the helical axis. The helical axis was defined by a rotation angle and a translation distance.

RESULTS

A total of 72 feet were included in the study. Thirty-one patients with unilateral symptoms and five healthy controls were selected, defining two groups: symptomatic (n = 31) and asymptomatic (n = 41). An absolute difference of 4.6º (95%CI 2-11.1) rotation angle was found on the helical axis of the symptomatic vs. asymptomatic group (p = 0.001). No significant differences were detected in the translation distance (n.s.) between the groups. Additionally, a significant positive correlation was found between the rotation angle and translation distance through the helical axis in the asymptomatic group (r = 0.397, p = 0.027).

CONCLUSION

Patients with chronic ankle instability suspected of having subtalar joint instability showed a wider subtalar range of laxity in terms of rotation about the helical axis. Furthermore, differences in kinematics between symptomatic and asymptomatic hindfeet was demonstrated when both feet were compared.

LEVEL OF EVIDENCE

III.

Evaluation of chronic ankle instability and subtalar instability using the angle between the anterior talofibular ligament and calcaneofibular ligament

PURPOSE

A series of studies have reported a change in the length or thickness of the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments in patients with chronic ankle instability. However, no study has examined the changes in the angle between the ATFL and CFL in patients diagnosed with chronic ankle instability. Therefore, this study analyzed the change in the angle between the ATFL and CFL in patients diagnosed with chronic ankle instability to confirm its relevance.

METHODS

This retrospective study included 60 patients who had undergone surgery for chronic ankle instability. Stress radiographs comprising the anterior drawer test, varus stress test, Broden's view stress test, and magnetic resonance imaging (MRI) were performed in all patients. The angle between the ATFL and CFL was measured by indicating the vector at the attachment site, as seen on the sagittal plane. Three groups were classified according to the angle between the two ligaments measured by MRI: group I when the angle was > 90°, Group II when the angle was 71-90°, and Group III when the angle was ≤ 70°. The accompanying injuries to the subtalar joint ligament were analyzed via MRI.

RESULTS

A comparison of the angles between the ATFL and CFL measured on MRI in Group I, Group II, and Group III with the angles measured in the operating room revealed a significant correlation. Broden's view stress test revealed a statistically significant difference among the three groups (p < 0.05). The accompanying subtalar joint ligament injuries differed significantly among the three groups (p < 0.05).

CONCLUSION

The ATFL-CFL angle in patients with ankle instability is smaller than the average angle in ordinary people. Therefore, the ATFL-CFL angle might be a reliable and representative measurement tool to assess chronic ankle instability, and subtalar joint instability should be considered if the ATFL-CFL angle is 70° or less.

LEVEL OF EVIDENCE

Level III.

Hindfoot motion through helical axis image-based on dynamic CT scan using an original simulated weightbearing device

BACKGROUND

Determining the treatment of subtalar joint (STJ) instability requires a better understanding of the biomechanical principles underlying the condition and, a proper diagnosis. This study aimed to analyze "in vivo" the range of motion of the subtalar joint (STJ) measured on two (2D) and three dimensions (3D) image-based on CT Scan using an original device that maintains a simulated weightbearing. The secondary goal was to correlate the 2D and 3D measurement.

METHODS

An observational study was conducted, using an original Dynamic Simulated Weightbearing Device. Asymptomatic ankles were included. Each subject underwent a CT scan under mechanical stress and simulated weightbearing conditions, maintaining maximum eversion and inversion hindfoot positions. The images were obtained, combining both inversion and eversion positions in a single model, which allows for to calculation of the motion vector as well as the helical axis. The helical axis (rotation angle and translation distance), subtalar tilt, anterior drawer, and, subtalar and calcaneocuboid uncoverage were the determinations.

RESULTS

Forty asymptomatic ankles were included. The average range of motion of the STJ amounts to 31.5° ± 9.1° of rotation and 1.56 ± 0.8 mm of translation distance. The anterior drawer and subtalar uncoverage variables were statistically significantly related to each other (r = 0.57; P = 0.00001). However, these 2-D measured variables were not related to kinematic measures of rotation through the helical axis (3D) (p = 0.14; p = 0.19) CONCLUSIONS: The average range of motion of the STJ amounts to 31.5° ± 9.1° of rotation and 1.56 ± 0.8 mm of translation distance. We found no significant correlation between 2D and 3D measurements. In our opinion, the rotation angle and translation distance should be considered the most accurate measurements and should be calculated on every STJ instability for comparison with the asymptomatic population LEVEL OF EVIDENCE: Observational study.

LEVEL OF EVIDENCE III

Examination of the Impact of Strength and Velocity of the Knee and Ankle on Gait Speed in Community-Dwelling Older Adults

The muscle strength of the knee extension and plantarflexion plays a crucial role in determining gait speed. Recent studies have shown that no-load angular velocity of the lower limb joints is essential for determining gait speed. However, no reports have compared the extent to which lower limb functions, such as knee extension strength, knee extension velocity, plantarflexion strength, and plantarflexion velocity, impact gait speed in a single study. Therefore, this study aimed to examine the relative importance of maximum strength and no-load angular velocity on gait speed. Overall, 164 community-dwelling older adults (72.9 ± 5.0 years) participated in this study. We measured the gait speed and lower limb function (the strength and velocity of knee extension and plantarflexion). Strength was measured with a hand-held dynamometer, and velocity with a gyroscope. A multiple regression analysis was performed with gait speed as the dependent variable and age, sex, and lower-limb function as independent variables. Plantarflexion velocity (β = 0.25) and plantarflexion strength (β = 0.21) were noted to be significant predictors of gait speed. These findings indicate that no-load plantarflexion velocity is more important than the strength of plantarflexion and knee extensions as a determinant of gait speed, suggesting that improvement in plantarflexion velocity may increase gait speed.

Anatomical parameters of sustentaculum Tali screw placement in the Asian population: A retrospective radio-anatomical study

Purpose: This study aimed to determine the anatomical parameters of successful Sustentaculum Tali (ST) screw placement in the Asian population. Method: CT scans of unilateral feet of 110 participants were reviewed, retrospectively. The 3 D reconstruction of the calcaneus and morphometric measurements were performed by Mimics Research 19.0 and 3-Matic Research 11.0. Finally, six cadaveric feet were used for verification of the accuracy of the measurements. Results: We discovered a method to help place ST screw successfully: (1) The entry point located at the middle section of the lateral wall of posterior talar articular surface (PTAS), and the perpendicular distance from the entry point to the lateral edge of PTAS (PDEL) was 10.78 mm, (2) Screw was perpendicular to the z-axis, 66.98° to the y-axis (the longitudinal axis of the foot), (3) The length of the ST screw should be approximately 44.74 mm in male and 41.14 mm in female, and (4) The diameter of the ST screw should be approximately 4.0 mm in male and 3.5 mm in female. With this new method, all screws in six cadaveric feet were placed successfully into the middle of ST. Conclusions: In this study, we discovered a general approach to safely place ST screws in the Asian population, which may potentially help surgeons improve their success rate in surgical practice.

Current Concepts on Subtalar Instability

Subtalar instability remains a topic of debate, and its precise cause is still unknown. The mechanism of injury and clinical symptoms of ankle and subtalar instabilities largely overlap, resulting in many cases of isolated or combined subtalar instability that are often misdiagnosed. Neglecting the subtalar instability may lead to failure of conservative or surgical treatment and result in chronic ankle instability. Understanding the accurate anatomy and biomechanics of the subtalar joint, their interplay, and the contributions of the different subtalar soft tissue structures is fundamental to correctly diagnose and manage subtalar instability. An accurate diagnosis is crucial to correctly identify those patients with instability who may require conservative or surgical treatment. Many different nonsurgical and surgical approaches have been proposed to manage combined or isolated subtalar instability, and the clinician should be aware of available treatment options to make an informed decision. In this current concepts narrative review, we provide a comprehensive overview of the current knowledge on the anatomy, biomechanics, clinical and imaging diagnosis, nonsurgical and surgical treatment options, and outcomes after subtalar instability treatment.

Secondary Effects of the Rupture and Reconstruction of the Interosseous Talocalcaneal Ligament on the Peritalar Joints

Background

The interosseous talocalcaneal ligament (ITCL) is the main soft-tissue contributor to subtalar joint stability. The role of ITCL reconstruction in retaining this stability is minimally reported. Therefore, we conducted this study to investigate the effects of rupture and reconstruction of the ITCL on the subtalar and peritalar joints.

Material/Methods

This experimental study randomly divided 72 rabbits into 3 equal groups of 24 rabbits each. Group I underwent reconstruction surgery, group II underwent resection, and group III was the control group. The cartilages between the talocrural and calcaneocrural joints, and between the subtalar and talonavicular joints on both sides were assessed by gross observation, ink staining, histology, and immunohistochemistry at weeks 4, 8, 16, and 32, postoperatively.

Results

In group II, the quantitative ink staining analysis revealed degeneration of the articular cartilages on the talonavicular joint (T=2.070, P=0.038) and the posterior subtalar joint (T=2.121, P=0.034) compared with the 2 sides of the same rabbit at 4 and 8 postoperative weeks. Comparing the operated sides of all the groups showed the posterior subtalar joints (Hc=9.563, P=0.008) and talonavicular joints (Hc=9.714, P=0.008) had an obvious difference at postoperative week 4; and in the calcaneocrural joints (Hc=6.750, P=0.034), it was noticed at postoperative week 8. Histology and immunohistochemistry findings confirm these observations.

Conclusions

An ITCL resection can lead to the progressive degeneration of the talonavicular and posterior subtalar joints, while an ITCL reconstruction can be beneficial in restoring the stability of these joints, preventing or postponing their degeneration, and protecting the articular cartilages.

Detecting Ankle Instability With an Instrumented Ankle Arthrometer: An Experimental Study

A new instrumented device was developed to quantify ankle joint stability during an anterior talar drawer test. The aim of the present study was to validate this device comparing bone kinematics with arthrometer measurement outcomes. An anterior talar drawer test was performed with 14 cadaver legs using a custom instrumented ankle arthrometer. Using clusters of bone-pin markers, the relative three-dimensional movement of calcaneus, talus, and fibula was simultaneously measured. Anterior drawer test was applied on the intact foot and after sequentially sectioning the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament. Cutting the anterior talofibular ligament caused a significant increase in bone-pin measured anterior translations of calcaneus and talus as well as in the anterior translation of the arthrometer. Analysis of receiver operating characteristic curves indicates a fair to good ability to discriminate between the intact and the sectioned conditions with the arthrometer. Distal distraction, inversion, and internal rotation movements were observed when two and three ligaments were cut. Results revealed that the ankle arthrometer was sensitive to detect changes in bone-to-bone movements during an anterior talar drawer test, when the anterior talofibular ligament was sectioned. Presumably due to movements in additional planes of motion, the arthrometer was not able to differentiate between situations with one or more ligaments cut. In conclusion, the instrumented anterior talar drawer tester may augment current procedures in assessing ankle instability primarily caused by ruptures of the anterior talofibular ligament. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2019-2026, 2019.

Stabilizing lateral ankle instability by suture tape - a cadaver study

BACKGROUND

Suture tape is a recent development to augment a Brostrom repair at least during the healing phase of the native tissues used for stabilization of the lateral ankle ligaments. The purpose of this study was to evaluate whether suture tape is an effective mechanical stabilizer against anterior talar drawer in a cadaver experiment when tested with a validated arthrometer.

METHODS

Different stability conditions were created in 14 cadaveric foot and leg specimens. Following anterior talofibular ligament (ATFL) dissection, isolated suture tape ATFL reconstruction was compared to the unaltered specimens, to the condition with ATFL cut, to the ATFL plus calcaneofibular ligament (CFL) cut conditions, and to the ATFL, CFL, and posterior talofibular ligament transected specimens. Three-dimensional bone-to-bone movement between fibula and calcaneus were simultaneously recorded using bone pin markers. Anterior translation was analysed between 20 and 40 N anterior talar drawer load, applied by an ankle arthrometer. Test conditions were compared using non-parametric statistics.

RESULTS

Dissection of ATFL increased anterior talar drawer in arthrometer and bone pin marker analyses (p = 0.003 and 0.004, respectively). When the CFL was additionally cut, no further increase of the anterior instability could statistically be documented (p = 0.810 and 0.626, respectively). Following suture tape reconstruction of the ATFL, stability was not different from the unaltered ankle (p = 0.173).

CONCLUSIONS

Suture tape augmentation of the ATFL effectively protects the unstable anterolateral ankle in the sagittal plane. The CFL does not seem to stabilize against the anterior talar drawer load.

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.

Function of ankle ligaments for subtalar and talocrural joint stability during an inversion movement - an in vitro study

Background

The lateral ankle ligament complex consisting of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the posterior talofibular ligament (PTFL) is known to provide stability against ankle joint inversion. As injuries of the ankle joint have been reported at a wide range of plantarflexion/dorsiflexion angles, the aim of the present study was to evaluate the stabilizing function of these ligaments depending on the sagittal plane positioning of the ankle joint.

Methods

Eight fresh-frozen specimens were tested on a custom-built ankle deflection tester allowing the application of inversion torques in various plantarflexion/dorsiflexion positions. A motion capture system recorded kinematic data from the talus, calcaneus and fibula with bone-pin markers during inversion movements at 10° of dorsiflexion, at neutral position and at plantarflexion 10°. ATFL, CFL and PTFL were separately but sequentially sectioned in order to assess the contribution of the individual ligament with regard to ankle joint stability.

Results

Joint- and position-specific modulations could be observed when the ligaments were cut. Cutting the ATFL did not lead to any observable alterations in ankle inversion angle at a given torque. But subsequently cutting the CFL increased the inversion angle of the talocrural joint in the 10° plantarflexed position, and significantly increased the inversion angle of the subtalar joint in the 10° dorsiflexed position. Sectioning of the PTFL led to minor increases of inversion angles in both joints.

Conclusions

The CFL is the primary ligamentous stabilizer of the ankle joint against a forced inversion. Its functioning depends greatly on the plantar−/dorsiflexion position of the ankle joint complex, as it provides the stability of the talocrural joint primarily during plantarflexion and the stability of the subtalar joint primarily during dorsiflexion.

Electronic supplementary material

The online version of this article (10.1186/s13047-019-0330-5) contains supplementary material, which is available to authorized users.

Effect of simulated joint instability and bracing on ankle and subtalar joint flexibility

It is clinically challenging to distinguish between ankle and subtalar joints instability in vivo. Understanding the changes in load-displacement at the ankle and subtalar joints after ligament injuries may detect specific changes in joint characteristics that cannot be detected by investigating changes in range of motion alone. The effect of restricting joints end range of motion with ankle braces was already established, but little is known about the effect of an ankle brace on the flexibility of the injured ankle and subtalar joints. Therefore, the purposes of this study were to (1) understand how flexibility is affected at the ankle and subtalar joints after sectioning lateral and intrinsic ligaments during combined sagittal foot position and inversion and during internal rotation and (2) investigate the effect of a semi-rigid ankle brace on the ankle and subtalar joint flexibility. Kinematics and kinetics were collected from nine cadaver feet during inversion through the range of ankle flexion and during internal rotation. Motion was applied with and without a brace on an intact foot and after sequentially sectioning the calcaneofibular ligament (CFL) and the intrinsic ligaments. Segmental flexibility was defined as the slope of the angle-moment curve for each 1 Nm interval. Early flexibility significantly increased at the ankle and subtalar joint after CFL sectioning during inversion. The semi-rigid ankle brace significantly decreased early flexibility at the subtalar joint during inversion and internal rotation for all ligament conditions and at the ankle joint after all ligaments were cut.

Anterolateral talar palpation: A complementary test for ankle instability

BACKGROUND

The anterior drawer test is traditionally used to assess ankle instability, but we believe that there is room for a small but effective improvement by adding digital palpation of the talus. We aimed to determine the accuracy of anterolateral talar palpation (ATP) in the diagnosis of ankle instability by comparing it with the traditional anterior drawer test.

METHODS

Fourteen symptomatic and 10 asymptomatic patients were examined for excessive mobility through comparison of both ankles by two blinded orthopedic surgeons, each one using one of the above-mentioned tests. Symptomatic patients were also referred for stress radiography and magnetic resonance imaging (MRI).

RESULTS

ATP was the most sensitive test, but also the least specific, yielding more positive results than the other tests, including tests with negative MRI. ATP and radiography had the highest accuracy and highest level of agreement with MRI.

CONCLUSIONS

ATP significantly improved diagnostic accuracy in detecting ankle instability.

LEVEL OF EVIDENCE

IV: cross-sectional study.

Update on Subtalar Joint Instability

Subtalar joint stability is ensured by the osseous geometry of the talocalcaneal joint and the complex array of the ligaments at the medial and lateral aspect of the ankle joint, the sinus and canalis tarsi, and the talocalcaneonavicular joint, respectively. There is still a substantial lack of knowledge about the interaction of the ankle and subtalar joint complex. Subtalar joint instability appears to be more frequent than is generally assumed. The diagnosis of chronic subtalar joint instability makes the application of a comprehensive algorithm necessary. There is ongoing debate about the preferable techniques for restoration of subtalar joint stability.

Effect of Direct Ligament Repair and Tenodesis Reconstruction on Simulated Subtalar Joint Instability

BACKGROUND

Subtalar instability is associated with up to 80% of patients presenting with chronic ankle instability but is often not considered in the diagnosis or treatment. Operative procedures to repair ankle instability have shown good clinical results, but the effects of these reconstruction procedures on isolated subtalar instability are not well understood. The goal of this study was to investigate the effect of the Gould modification of the Broström procedure and a new tenodesis reconstruction procedure on ankle and subtalar joint kinematics after simulating a subtalar injury.

METHODS

Kinematic data were collected on 7 cadaveric ankles during inversion through the range of ankle flexion and during internal rotation. Testing was performed on the intact foot; after sectioning the calcaneofibular ligament, cervical ligament, and interosseous talocalcaneal ligament; after the Gould modification of the Broström procedure was performed; and after tenodesis was performed and sutures from the Gould modification removed.

RESULTS

The Gould modification of the Broström procedure significantly decreased subtalar and ankle inversion motion and subtalar internal rotation compared to the unstable condition. The tenodesis method restricted internal rotation at the subtalar joint and ankle inversion compared to the intact state.

CONCLUSION

Both operative procedures improved stability of the ankle complex, but tenodesis was unable to restore subtalar inversion and restricted ankle inversion in maximum plantarflexion.

CLINICAL RELEVANCE

The Gould modification of Broström ligament repair may be a favorable operative procedure for the restoration of subtalar and ankle joint kinematics.

Orientation of the Subtalar Joint: Measurement and Reliability Using Weightbearing CT Scans

BACKGROUND

Up to 60% of patients with an osteoarthritic ankle joint develop talar tilt with progression of the osteoarthritic process. The configuration of the subtalar joint, in particular the posterior facet, may contribute to the development of this wear pattern. Recently, the subtalar vertical angle (SVA) was used to describe the posterior facet of the subtalar joint in the frontal plane. The aim of this work was to analyze if the orientation of the subtalar joint may influence the type of asymmetric ankle osteoarthritis.

METHODS

In total, 60 ankles were retrospectively analyzed including 40 osteoarthritic patients and 20 healthy controls. The osteoarthritic ankles were divided into 4 groups: varus ankle joints with (incongruent) or without (congruent) a tilted talus and valgus ankle joints with (incongruent) or without (congruent) a tilted talus. The orientation of the subtalar joint was described using the SVA. The SVA was determined for every patient using weightbearing CT scans. Additionally, the inter- and intraobserver reliability was assessed using intraclass correlation coefficients (ICCs).

RESULTS

The inter- and intraobserver reliability was excellent (ICC > 0.989 and >0.975, respectively). The varus groups (incongruent and congruent) had significantly lower SVA values, that is, more varus orientation of the subtalar joint than the valgus groups (P < .05). The SVA of the control group was between the values of the varus and valgus ankles.

CONCLUSION

The SVA provided a reliable and consistent method to assess the varus/valgus configuration of the posterior facet of the subtalar joint. In our cohort, varus osteoarthritis of the ankle joint occurred with varus orientation of the subtalar joint whereas in patients with valgus osteoarthritis, valgus orientation of the subtalar joint was found. Our data suggest that the subtalar joint orientation may be a risk factor for the development of ankle joint osteoarthritis.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

Subtalar joint instability

PURPOSE

Subtalar joint instability may frequently be overlooked and erroneously be integrated under the diagnosis of ankle joint instability. It was the scope of this review to characterize the present state-of-art with regard to the adequate diagnosis and treatment.

METHODS

While the clinical picture is mostly inconclusive for subtalar joint instability, a high degree of suspicion for this diagnosis is needed to employ weight-bearing x-rays, standardized stress radiography, CT scanning and MRI to further elucidate the etiopathology

RESULTS

Geometrical reasons as hindfoot deformities, isolated or combined injuries or instabilities in conjunction with the ankle ligament complex do exist which should be differentiated in detail and classified to indicate the adequate treatment. Treatment of acute lesions is simple and effective. A certain percentage of the patients with chronic subtalar instability is incorrectly labeled with the diagnosis of a sinus tarsi syndrome.

CONCLUSION

Subtalar joint arthroscopy for reconfirmation of the correct diagnosis conjoined with restoration of physiological hindfoot alignment and a preferably anatomical ligamentous reconstruction provide the basis for a good functional recovery.

Outcome of subtalar instability reconstruction using the semitendinosus allograft tendon and biotenodesis screws

PURPOSE

Subtalar instability (STI) has often been obscured by lateral ankle instability. Moreover, although there have been several reports of techniques for reconstructing STI, no clinical outcome results are known to have been published. The authors report the clinical and radiographic outcomes of the ligament reconstruction of STI with a recently reported novel technique utilising a semitendinosus tendon allograft and interference screws.

METHODS

This study is based on 20 ankles that underwent ligament reconstruction for STI between 2009 and 2013. The average follow-up period was 15.0 ± 5 months, and the average age at surgery was 28.1 ± 10.8 years old. Visual analogue (VAS) pain scores, American Orthopedic Foot and Ankle Society (AOFAS) and Karlsson-Peterson ankle scores as well as patient satisfaction were evaluated. Radiographic evaluation of medial translations of calcaneus and subtalar tilt angles was preformed with ankle and Broden's stress radiographs.

RESULTS

The VAS pain score decreased from 6.1 ± 1.1 preoperatively to 1.8 ± 1.2 post-operatively (p < 0.05). The AOFAS score improved from 66.0 ± 12.2 preoperatively to 89.6 ± 6.7 post-operatively, and the Karlsson-Peterson score improved from 57.0 ± 13.5 to 91.1 ± 6.8 (p < 0.05). There were no complications such as recurred STI or subtalar joint stiffness. All of the patients were satisfied with the surgery. Subtalar tilt angle decreased from 11.5° preoperatively to 3.0° post-operatively, and the calcaneal medial translations decreased from 7.4 to 3.9 mm.

CONCLUSION

This is the first report on the comprehensive clinical and radiographic outcomes of STI reconstruction using a semitendinosus tendon allograft and interference screws. The novel technique of STI reconstruction was found to show encouraging clinical outcomes with high patient satisfaction.

LEVELS OF EVIDENCE

IV.

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.

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.