Subject-specific models of the hindfoot reveal a relationship between morphology and passive mechanical properties.
ABSTRACT: The morphology of the bones, articular surfaces and ligaments and the passive mechanical characteristics of the ankle complex were reported to vary greatly among individuals. The goal of this study was to test the hypothesis that the variations observed in the passive mechanical properties of the healthy ankle complex are strongly influenced by morphological variations. To evaluate this hypothesis six numerical models of the ankle joint complex were developed from morphological data obtained from MRI of six cadaveric lower limbs, and from average reported data on the mechanical properties of ligaments and articular cartilage. The passive mechanical behavior of each model, under a variety of loading conditions, was found to closely match the experimental data obtained from each corresponding specimen. Since all models used identical material properties and were subjected to identical loads and boundary conditions, it was concluded that the observed variations in passive mechanical characteristics were due to variations in morphology, thus confirming the hypothesis. In addition, the average and large variations in passive mechanical behavior observed between the models were similar to those observed experimentally between cadaveric specimens. The results suggest that individualized subject-specific treatment procedures for ankle complex disorders are potentially superior to a one-size-fits-all approach.
Project description:Background:Anatomic lateral ankle ligament reconstruction has been proposed for patients with chronic ankle instability. A reliable approach is a reconstruction technique using an allograft and 2 fibular tunnels. A recently introduced approach that entails 1-fibular tunnel reconstruction might reduce the risk of intraoperative complications and ultimately improve patient outcome. Hypothesis:We hypothesized that both reconstruction techniques show similar ankle stability (joint laxity and stiffness) and are similar to the intact joint condition. Study Design:Controlled laboratory study. Methods:A total of 10 Thiel-conserved cadaveric ankles were divided into 2 groups and tested in 3 stages-intact, transected, and reconstructed lateral ankle ligaments-using either the 1- or the 2-fibular tunnel technique. To quantify stability in each stage, anterior drawer and talar tilt tests were performed in 0°, 10°, and 20° of plantarflexion (anterior drawer test) or dorsiflexion (talar tilt test). Bone displacements were measured using motion capture, from which laxity and stiffness were calculated together with applied forces. Finally, reconstructed ligaments were tested to failure in neutral position with a maximal applicable torque in inversion. A mixed linear model was used to describe and compare the outcomes. Results:When ankle stability of intact and reconstructed ligaments was compared, no significant difference was found between reconstruction techniques for any flexion angle. Also, no significant difference was found when the maximal applicable torque of the 1-tunnel technique (9.1 ± 4.4 N·m) was compared with the 2-tunnel technique (8.9 ± 4.8 N·m). Conclusion:Lateral ankle ligament reconstruction with an allograft using 1 fibular tunnel demonstrated similar biomechanical stability to the 2-tunnel approach. Clinical Relevance:Demonstrating similar stability in a cadaveric study and given the potential to reduce intraoperative complications, the 1-fibular tunnel approach should be considered a viable option for the surgical therapy of chronic ankle instability. Clinical randomized prospective trials are needed to determine the clinical outcome of the 1-tunnel approach.
Project description:Arthroscopic lateral ankle ligament reconstruction has been recently advocated. But this technique has not been popularized because of the technical complexity and potential iatrogenic injury. Because the talocalcaneal and calcaneofibular ligaments are extra-articular structures, how to efficiently view and address them is a difficult task. Limited dissection outside the capsule to form a working space is required, but aggressive dissection is harmful for tissue healing although it is helpful for visualization and instrumentation. Because almost the entire talar body is covered by articular cartilage, it is very difficult to safely make a bone tunnel without damaging the cartilage. The remnants of the lateral ankle ligament have proprioceptive sensors that are important for functional stability, but it is difficult to perform anatomical reconstruction arthroscopically while preserving them because of the narrow working space. Furthermore, how to properly tension the reconstructed ligaments in such a narrow working space is also a very difficult task. We have designed a technique that preserves the remnants of lateral ankle ligaments, and all of the above-mentioned problems have been successfully addressed. We have used this technique clinically, and only minor complications occurred.
Project description:The open anatomic repair of the anterior talofibular and calcaneofibular ligaments (modified Brostrom procedure) is widely accepted as the standard surgical stabilization procedure for lateral ankle instability that does not respond to conservative measures. Arthroscopic Brostrom procedures with a suture anchor have been reported to achieve both anatomic repair of the lateral ankle ligaments and management of the associated intra-articular lesions. However, the complication rates are higher than open Brostom procedures. Many of these complications are associated with the use of a suture anchor. We report a modified arthroscopic Brostrom procedure in which the anterolateral ankle capsule is anchored to the lateral malleolus through small bone tunnels instead of suture anchors.
Project description:INTRODUCTION:Subtalar joint (STJ) dysfunction can contribute to movement disturbances. Vibration energy with color Doppler imaging (VECDI) may be useful for detecting STJ stiffness changes. OBJECTIVES:(1) Support proof-of-concept that VECDI could detect STJ stiffness differences; (2) Establish STJ stiffness range in asymptomatic volunteers; (3) Examine relationships between STJ stiffness and foot mobility; and (4) Assess VECDI precision and reliability for examining STJ stiffness. METHODS:After establishing cadaveric testing model proof-of-concept, STJ stiffness (threshold units, ?TU), ankle complex passive range-of-motion (PROM) and midfoot-width-difference (MFWDiff) data were collected in 28 asymptomatic subjects in vivo. Three reliability measurements were collected per variable; Rater-1 collected on all subjects and rater-2 on the first ten subjects. Subjects were classified into three STJ stiffness groups. RESULTS:Cadaveric VECDI measurement intra-rater reliability was 0.80. A significantly lower STJ ?TU (p = .002) and ankle complex PROM (p < .001) was observed during the screw fixation versus normal condition. A fair correlation (r = 0.660) was observed between cadaveric ?TU and ankle complex PROM. In vivo VECDI measurements demonstrated good intra-rater (0.76-0.84) versus poor inter-rater (-3.11) reliability. Significant positive correlations were found between STJ stiffness and both dorsum (r = .440) and posterior (r = .390) PROM. MFWDiff exhibited poor relationships with stiffness (r = .103) and either dorsum (r = .256) or posterior (r = .301) PROM. STJ stiffness ranged from 2.33 to 7.50 ?TUs, categorizing subjects' STJ stiffness as increased (n = 6), normal (n = 15), or decreased (n = 7). Significant ANOVA main effects for classification were found based on ?TU (p< .001), dorsum PROM (p = .017), and posterior PROM (p = .036). Post-hoc tests revealed significant: (1) ?TU differences between all stiffness groups (p < .001); (2) dorsum PROM differences between the increased versus normal (p = .044) and decreased (p = .017) stiffness groups; and (3) posterior PROM differences between the increased versus decreased stiffness groups (p = .044). A good relationship was found between STJ stiffness and dorsum PROM in the increased stiffness group (r = .853) versus poor, nonsignificant relationships in the normal (r = -.042) or decreased stiffness (r = -.014) groups. CONCLUSION:PROM may not clinically explain all aspects of joint mobility. Joint VECDI stiffness assessment should be considered as a complimentary measurement technique.
Project description:Lateral ankle sprains are common; if conservative treatment fails and chronic instability develops, stabilization surgery is indicated. Numerous surgical procedures have been described, but those that most closely reproduce normal ankle lateral ligament anatomy and kinematics have been shown to have the best outcomes. Arthroscopy is a common adjunct to open ligament surgery, but it is traditionally only used to improve the diagnosis and the management of any associated intra-articular lesions. The stabilization itself is performed open because standard anterior ankle arthroscopy provides only partial visualization of the anterior talofibular ligament from above and the calcaneofibular ligament attachments cannot be seen at all. However, lateral ankle endoscopy can provide a view of this area that is superior to open surgery. We have developed a technique of ankle endoscopy that enables anatomic positioning of the repair or fixation of the graft. In this article we describe a safe and reproducible arthroscopic anatomic reconstruction of the lateral ligaments of the ankle using a gracilis autograft. The aim of this procedure is to obtain a more physiological reconstruction while maintaining all the advantages of an arthroscopic approach.
Project description:Analysis of gene expression in E16 mouse meniscus, articular cartilage, and cruciate ligaments Limbs were dissected from E16 CD-1 mice. Samples were frozen in OCT and cryosectioned. Meniscus, articular carilage, and cruciate ligament were isolated using laser capture microdissection. Total RNA was isolated from these tissues, amplified, and gene expression was analyzed using microarrays. Three biological replicates were analyzed for each tissue type. Total RNA extracted from E16 mouse meniscus, articular cartilage, and cruciate ligaments
Project description:Ankle instability is a condition that often requires surgery to stabilize the ankle joint that will improve pain and function if nonoperative treatments fail. Ankle stabilization surgery may be performed as a repair in which the native existing anterior talofibular ligament or calcaneofibular ligament (or both) is imbricated or reattached. Alternatively, when native ankle ligaments are insufficient for repair, a reconstruction of the ligaments may be performed in which an autologous or allograft tendon is used to reconstruct the anterior talofibular ligament or calcaneofibular ligament (or both). Currently, ankle stabilization surgery is most commonly performed through an open incision, but arthroscopic ankle stabilization using repair techniques has been described and is being used more often. We present our technique for anatomic ankle arthroscopic reconstruction of the lateral ligaments (anti-ROLL) performed in an all-inside-out manner that is likely safe for patients and minimally invasive.
Project description:Deltoid ligament injuries account for 5.1% to 15.8% of ankle sprains and occur with concomitant lateral ankle sprains. The anterior tibiotalar ligament (ATTL), located within the deep layer of the deltoid ligament complex, connects the talus and the tibia on the medial side of the ankle and controls ankle eversion and rotation. If conservative treatment for chronic medial ankle instability after an ankle sprain fails, ATTL repair or reconstruction might be necessary. Arthroscopic reconstruction techniques of the lateral ankle ligaments recently have been reported. Here, we describe arthroscopic reconstruction of the ATTL using a free tendon graft (ARATTL). This technique is less invasive than other treatments and results in a more stable medial ankle joint.
Project description:Injuries to the acromioclavicular (AC) joint are becoming common with contact sports and bike accidents. It is well known that in AC dislocations, the first structure to fail is the AC capsule followed by the trapezoid and conoid ligaments. The function of these ligaments must be restored to restore the anatomy and physiology of the AC joint to get the best results. Until now, no technique has emerged as the gold standard for restoration of the AC joint anatomy and function. In our technique, the stress is on recreating the anatomy to make it more individualized based on individual variations. This Technical Note describes a procedure to reconstruct the coracoclavicular ligaments and AC joint by an arthroscopy-assisted technique. Arthroscopy helps to diagnose additional intra-articular pathologies that can be treated simultaneously, and better preparation of the undersurface of the coracoid helps in bone-to-graft healing. Our approach is more individualized as clavicle tunneling is done according to the size of the coracoid base instead of a fixed distance. Vertical stability is provided by coracoclavicular ligament reconstruction, horizontal stability is provided by AC ligament reconstruction, and the articular disc is recreated by soft-tissue graft interposition, thus restoring the complete anatomy.
Project description: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.