Posterior Talocalcaneal Joint Research Articles

Quantitative MRI Analysis of the Talocrural and Talonavicular Joints in Ballet Dancers.

The ankles of ballet dancers are routinely under heavy loading that may lead to osteoarthritic changes. It would be clinically useful to identify such pathology as early as possible in a dancer's career. Therefore, the purpose of this study was to compare quantitative measurements in magnetic resonance (MR) images of the talocrural and talonavicular joints in ballet dancers and healthy non-dancers for use in formulating prediction of chronic injury and degenerative joint disease in these locations. Quantitative measurements in MR images of the talocrural and talonavicular joints were compared in 10 female ballet dancers, 10 healthy female non-dancers, and nine male ballet dancers. Fat-suppressed density-weighted proton, T1rho, and T2 mapping images were acquired with a 3.0 T MR scanner. Medial and lateral subchondral bone distance between the tibia and talus (MSBD and LSBD), axial navicular-talus axis angle (ANT angle), sagittal talar neck angle against the posterior talocalcaneal joint (TN angle), and curvature of navicular surface at the talonavicular joint were measured on sagittal images. The medial subchondral bone distance was found to be significantly larger in female dancers than female non-dancers (4.05 mm vs. 2.75 mm, p < 0.05), whereas there were no significant differences in LSBD (2.63 mm vs. 2.63 mm, p = 0.87). Axial navicular talus angles in female dancers were significantly larger than those in female non-dancers (38.9° vs. 24.3°, p < 0.05). There was a tendency for the TN angle to be smaller and navicular curvature (NC) to be larger in female dancers compared to female non-dancers, though the differences were not significant (TN angle: 16.6° vs. 22.3°, p = 0.09, and NC: 0.186 vs. 0.165, p = 0.28). There were no significant differences in T1rho or T2 values of talonavicular joint cartilage. These results show that the bony anatomy of dancers' ankles may adapt to the stresses placed on them by ballet.

Arthroscopic Mobilization of the Ankle-subtalar Joint Complex Using a Novel “Infra-fibula-tip” Portal

Category:Arthroscopy; HindfootIntroduction/Purpose:As a minimally invasive surgical option for posterior ankle/subtalar pathologies, the prone hindfoot endoscopy (a.k.a. Van-Dijk’s method) has been becoming the ‘gold standard’ technique. While this technique holds advantage regarding good orientation and safety handling of posteromedial pathologies, it limits access to the anterolateral part, therefore inconvenient when simultaneously dealing with anterior and posterior pathologies. Recently, we have introduced a novel ‘infra- fibula-tip (IFT)’ portal, which permits wide access to the posterior talocalcaneal joint (PTCJ), from anterolateral to posteromedial, with a patient positioned in supine or semi-lateral. The present study reviewed clinical outcomes of a case series of arthroscopic hindfoot mobilization using this new surgical technique, so as to document its clinical utility.Methods:The sequence of surgical procedures is as follows; - Create an IFT portal, from a small incision immediately distal to the fibular tip, through the peroneal tendon sheath (anterior to the tendons, but posterior to the calcanofibular ligament), toward the posterior porch of PTCJ.- Inserting a 30-deg 2.7mm scope to the posterior porch, and broadly observing posterior intraarticular findings.- Gently moving the scope to the anterolateral porch, and broadly observing anterolateral intraarticular findings.- Creating an anterolateral (AL) portal under arthroscopic guidance.- Creating a PL portal at immediately lateral to the Achilles tendon, with guidance of a blunt rod inserted from the AL portal (gently advanced posteriorly through the lateral recess and penetrated the rod toward subcutis).- Executing posterior procedures from the PL portal, while observing from the IFT portal. Executing anterolateral procedures working from the AL portal, while observing from the IFT portal.Results:A total of 7 cases underwent the procedure of interest to date. Subtalar osteoarthritis (OA) occurred in all, with accessory anterolateral talar facet (AALTF) impingement in 3. Ankle OA occurred in 3, with anterior bony impingement in 2. Preceding pathologies included peri-ankle intraarticular fractures (4), talocalcaneal coalition (2), and neurogenic varus foot (1). Mobilization procedures included lateral-to-posterior PTCJ debridement (7), coalition release (2), AALTF removal (3), sinus debridement (2), posterior ankle capsule release (2), anterior ankle debridement (2), talonavicular debridement (1), and Achilles tendon lengthening (1). The surgery duration ranged from 65 to 245 minutes. Postoperatively, of 4 cases followed more than 6 months, remarkable motion improvement (10 degrees or more) occurred in 3, and every case reported symptom relief.Conclusion:The IFT portal accesses the middle of the PTCJ, with a short skin-to-joint distance, allowing flexible exploration of both the posterior and anterior porches. Posteriorly, ability of direct intraarticular access (without extraarticular shaving) reduces surgical invasion, as well as the risk of potential neurovasucular injury. Anteriorly, it helps secure good triangulation for handling sinus pathologies. Since subtalar arthroscopy using the IFT portal is doable in a supine or semi-lateral position, anterior ankle arthroscopy could be simultaneously executed. Arthroscopic hindfoot mobilization using this technique appears to be efficient for dealing with ankle/subtalar contracture due to combined anterior and posterior pathologies.

Anatomy of the Tarsal Canal and Sinus in Relation to the Subtalar Joint Capsule.

Anatomical knowledge of the tarsal canal and sinus is still unclear owing to the complexity of the ligamentous structures within them, particularly the relationship with the capsules of the subtalar joints. The aim of this study was to examine the anatomical relationship between the fibrous tissues of the tarsal canal and sinus and the articular capsules of the subtalar joint. We conducted a descriptive anatomical study of 21 embalmed cadaveric ankles. For a macroscopic overview of the subtalar joint, we removed the talus in 18 ankles and separated the fibrous tissues from the surrounding connective tissues to analyze the layered relationship between the inferior extensor retinaculum (IER) and the subtalar joint capsule. Additionally, we histologically analyzed the tarsal canal and the medial and lateral sides of the tarsal sinus using Masson's trichrome staining in 3 ankles. The medial and intermediate roots of the IER and interosseous talocalcaneal ligament (ITCL) were located in the same layer and were connected to each other, between the capsules of the posterior talocalcaneal and talocalcaneonavicular joints. The intermediate root of the IER and the cervical ligament (CL) had adjacent attachments on the tarsal sinus, and synovial tissues originating from the joint capsules filled the remaining area in the tarsal canal and sinus. We determined that the tarsal canal and sinus tarsi contained 3 layered structures: the anterior capsule of the posterior talocalcaneal joint, including the anterior capsule ligament; the layer of ITCL and IER; and the posterior capsule of the talocalcaneonavicular joint, including the CL. The results of this study may help with the understanding of the pathomechanism of subtalar instability and sinus tarsi syndrome, resulting in better treatment.

Systematic CT evaluation of reduction and hardware positioning of surgically treated calcaneal fractures: a reliability analysis

IntroductionUp to date, there is a lack of reliable protocols that systematically evaluate the quality of reduction and hardware positioning of surgically treated calcaneal fractures. Based on international consensus, we previously introduced a 23-item scoring protocol evaluating the reduction and hardware positioning in these fractures based on postoperative computed tomography. The current study is a reliability analysis of the described scoring protocol.MethodsThree raters independently and systematically evaluated anonymized postoperative CT scans of 102 surgically treated calcaneal fractures. A selection of 25 patients was scored twice by all individual raters to calculate intra-rater reliability. The scoring protocol consisted of 23 items addressing quality of reduction and hardware positioning. Each of these four-option questions was answered as: ‘optimal’, ‘suboptimal (but not needing revision)’, ‘not acceptable (needing revision)’ or ‘not judgeable’. We used intraclass correlation coefficients (ICC’s) to calculate inter- and intra-rater reliability.ResultsInter-rater reliability of the overall 23-item protocol was good (ICC 0.66, 95% CI 0.64–0.69). Individual items that scored an inter-rater ICC ≥0.60 included evaluation of the calcaneocuboid joint, the posterior talocalcaneal joint, the anterior talocalcaneal joint, the position of the plate and sustentaculum screws and screws protruding the tuber and medial wall. The intra-rater reliability for the overall protocol was good for all three individual raters with ICC’s between 0.60 and 0.70.ConclusionOur scoring protocol for the radiological evaluation of operatively treated calcaneal fractures is reliable in terms of inter- and intra-rater reliability.

Percutaneous Reduction and Screw Fixation of Displaced Intra-articular Fractures of the Calcaneus.

Extensile open approaches to reduce and fix intra-articular calcaneal fractures are associated with high levels of wound complications. To avoid these complications, a technique of percutaneous reduction and fixation with screws alone was developed. This study assessed the clinical outcomes, radiographs, and postoperative CT scans after operative treatment with this technique. 153 consecutive patients with 182 intra-articular calcaneal fractures were reviewed. All patients were assessed for early postoperative complications at 3 months from the injury. The clinical results were assessed for patients seen at a minimum of 1 year after surgery (mean follow-up of 2.6 years; 90 patients, 106 feet). In patients who had both preoperative and postoperative CT scans (50 patients, 60 feet), the articular reduction was quantitatively analyzed. At the 3-month follow-up, there were 1% superficial infections and 1% rate of screw irritation. The complications at a minimum of 1 year after injury included screw irritation 9.3%, subtalar osteoarthritis requiring subtalar fusion 5.5%, malunion 1.8%, and deep infection 0.9%. Bohler angle, calcaneal facet height, and width were significantly improved postoperatively ( P < .01). Bohler angle increased on average +24.1 degrees postoperatively with a loss of angle of 4.9 degrees at the 3-month follow-up. There was significant improvement ( P < .01) in posterior talocalcaneal joint reduction on postoperative CT scan but residual displacement remained. At the final follow-up, 54.5% of the patients reported a residual pain level of 3 or lower. This study suggests that reasonable early results could be achieved from the percutaneous treatment of intra-articular calcaneal fractures using screws alone based on articular reduction and level of residual pain. Level IV, retrospective case series.

Conarticular congruence of the hominoid subtalar joint complex with implications for joint function in Plio-Pleistocene hominins.

The purpose of this study is to test the hypothesis that conarticular surfaces areas and curvatures are correlates of mobility at the hominoid talocalcaneal and talonavicular joints. Articular surface areas and curvatures of the talonavicular, anterior talocalcaneal, and posterior talocalcaneal joints were quantified using a total of 425 three-dimensional surface models of extant hominoid and fossil hominin tali, calcanei, and naviculars. Quadric surface fitting was used to calculate curvatures, pairwise comparisons were used to evaluate statistical differences between taxa, and regression was used to test for the effects of allometry. Pairwise comparisons show that the distributions of values for joint curvature indices follow the predicted arboreal-terrestrial morphocline in hominoid primates with no effect of body mass (PGLS p > 0.05). OH 8 (Homo habilis) and LB 1 (Homo floresiensis) can be accommodated within the range of human variation for the talonavicular joint, whereas MH2 (Australopithecus sediba) falls within the ranges of variation for Pan troglodytes and Gorilla gorilla in measures of posterior talocalcaneal joint congruity. Joint curvature indices are better discriminators than joint surface area indices, which may reflect a greater contribution of rotation, rather than translation, to joint movement in plantigrade taxa due to discrepancies in conarticular congruence and the "convex-concave" rule. The pattern of joint congruence in Au. sediba contributes to other data on the foot and ankle suggesting that the lateral side of the foot was more mobile than the medial side, which is consistent with suggestions of increased medial weight transfer associated with hyperpronation. Am J Phys Anthropol 160:446-457, 2016. © 2016 Wiley Periodicals, Inc.

Subtalar Joint Stress Imaging With Tomosynthesis

The purpose of this study was to perform stress imaging of hindfoot inversion and eversion using tomosynthesis and to assess the subtalar joint range of motion (ROM) of healthy subjects. The subjects were 15 healthy volunteers with a mean age of 29.1 years. Coronal tomosynthesis stress imaging of the subtalar joint was performed in a total of 30 left and right ankles. A Telos stress device was used for the stress load, and the load was 150 N for both inversion and eversion. Tomographic images in which the posterior talocalcaneal joint could be confirmed on the neutral position images were used in measurements. The angle of the intersection formed by a line through the lateral articular facet of the posterior talocalcaneal joint and a line through the surface of the trochlea of the talus was measured. The mean change in the angle of the calcaneus with respect to the talus was 10.3 ± 4.8° with inversion stress and 5.0 ± 3.8° with eversion stress from the neutral position. The result was a clearer depiction of the subtalar joint, and inversion and eversion ROM of the subtalar joint was shown to be about 15° in healthy subjects. Diagnostic, Level IV.

Stabilization of Joint Forces of the Subtalar Complex via HyProCure Sinus Tarsi Stent

The foot is the foundation of the body. The stability of the osseous hindfoot structure is crucial in bipedal locomotion. The subtalar joint is responsible for conversion of the rotatory forces of the lower extremities and dictates the movements of the midtarsal joints and the forefoot. In a hyperpronated foot, excessive abnormal pronation results in partial to full obliteration of the sinus tarsi. The hypothesis is that the HyProCure device will prevent obliteration of the sinus tarsi, thereby stabilizing the subtalar joint complex and eliminating the excessive forces to the proximal and distal musculoskeletal system that occur with every step. Five fresh-frozen human foot cadaver specimens that represented pathologic hindfoot and midfoot instability and partial to full obliteration of the sinus tarsi were axially compressed to 2,000 N and internally rotated by 15° to produce maximum pronation of the subtalar joint using a biaxial materials testing machine. The forces were measured across the posterior and anterior talocalcaneal joint facets before and after placement of the HyProCure stent. The subtalar joint stabilized after placement of the HyProCure sinus tarsi stent. The mean ± 1 SD forces in the posterior talocalcaneal joint increased from 795.88 ± 106 N to 1,004.86 ± 72.41 N (P < 0.05, two-tailed paired t test). The mean ± SD forces at the anterior talocalcaneal joint decreased from 520.15 ± 127.18 N to 394.56 ± 73.83 N (P < 0.05), shifting the contact area posteriorly. Placement of the HyProCure subtalar stabilization stent in a hyperpronated foot prevents excessive talar subluxation and assists in proper distribution of the axial loads on the subtalar facet joints.

Magnetic Resonance Imaging of anatomical variants of the subtalar joint

To evaluate MRI with thin slices to depict anatomical variations of the subtalar and talocalcaneonavicular joints. Ankle MRI was performed in 51 patients. The articular configurations were differentiated on sagittal T1-weighted and three-dimensional (3D) DESS images. Multiplanar reconstructions were performed. The variation in curvature of the posterior facet of the calcaneus and talus was analysed. 3D surface-rendered images of the calcaneus were obtained. All images were studied by an experienced physical therapist. Analysis revealed that 18 (36.7%) of the subjects had 3 distinct facets on the calcaneus. A missing anterior facet was revealed in five (10.2%) of subjects. Twenty-six (53.1%) subjects showed a fusion of the anterior and middle facets. In four cases, an articulation was found between the talus and the cuboid bone. At the posterior talocalcaneal articulation, variations were observed of the curvature of the medial side of the joint. The configuration of the facets of the talocalcaneal joints can be analysed on MR images. On 3D images, an articular connection was seen between the talus and the cuboid bone, as well as variations in the curvature of the posterior talocalcaneal joint. These anatomical variations may have implications for mobility and stability of the ankle.

Technique et expérience initiale de l’arthrodèse tibio-talocalcanéenne postérieure par arthroscopie

Tibiotalocalcaneal arthrodesis is indicated for pain relief in patients with combined arthritis of the ankle and subtalar joint. An arthroscopic posterior approach was designed to improve upon traditional methods by using a minimally invasive technique. The technique involves prone positioning of the patient, one anterolateral and two posterolateral portals, and arthroscopic debridement of both the tibiotalar and posterior talocalcaneal joint. Stabilisation is obtained with a retrograde intramedullary nail, with static interlocking. This article presents illustrative cases and discusses some of the technical advantages and disadvantages over conventional open surgery. For surgeons familiar with posterior ankle or subtalar arthroscopy, this minimally invasive debridement and nailing appears to offer superior exposure, high patient satisfaction and lower postoperative morbidity than traditional methods; fusion is encouraged by preserving the medullary reaming material at the site of the fusion.

Technique and early experience with posterior arthroscopic tibiotalocalcaneal arthrodesis

Tibiotalocalcaneal arthrodesis is indicated for pain relief in patients with combined arthritis of the ankle and subtalar joint. An arthroscopic posterior approach was designed to improve upon traditional methods by using a minimally invasive technique. The technique involves prone positioning of the patient, one anterolateral and two posterolateral portals, and arthroscopic debridement of both the tibiotalar and posterior talocalcaneal joint. Stabilisation is obtained with a retrograde intramedullary nail, with static interlocking. This article presents illustrative cases and discusses some of the technical advantages and disadvantages over conventional open surgery. For surgeons familiar with posterior ankle or subtalar arthroscopy, this minimally invasive debridement and nailing appears to offer superior exposure, high patient satisfaction and lower postoperative morbidity than traditional methods; fusion is encouraged by preserving the medullary reaming material at the site of the fusion.

Large bone distractor for open reconstruction of articular fractures of the calcaneus

The results of operative treatment of two groups of patients with articular fractures of the calcaneus were evaluated. Twenty-three cases were treated surgically using a standard reconstruction procedure. In the second group of 19 patients a large bone distractor was used; it held the soft tissue flap retracted, while aiding in articular and tuberosity fragment reduction and increasing visualisation by distraction of the posterior talocalcaneal joint. After a year, the anatomical and functional results, together with the operative time, were evaluated. All fractures healed with good or very good anatomical results. All cases, except those with complications (n = 3), achieved good (n = 28) or very good (n = 11) functional scoring. The distractor group had significantly shorter operative times, and less manpower was needed during surgery. We conclude that the large bone distractor is a useful tool in open reconstruction of articular calcaneal fractures.

A 3-portal approach for arthroscopic subtalar arthrodesis

We present a 3-portal approach for arthroscopic subtalar arthrodesis with the patient in the prone position. The prone position allows the use of the two standard posterior portals and it allows for accurate control of hindfoot alignment during surgery. Furthermore, the introduction of talocalcaneal lag screws is easy with the patient in this position. In addition to the standard posterior portals, an accessory third portal is created at the level of the sinus tarsi for introduction of a large diameter blunt trocar to open up the subtalar joint. Due to the curved geometry of the posterior subtalar joint, removal of the anterior articular cartilage is impossible by means of the posterior portals only. An advantage of the 3-portal approach is that ring curettes can be introduced through the accessory sinus tarsi portal to remove the articular cartilage of the anterior part of the posterior talocalcaneal joint. Arthroscopic subtalar arthrodesis in patients with a talocalcaneal coalition presents a technical challenge as the subtalar joint space is limited. The 3-portal technique was successfully used in three subsequent patients with a talocalcaneal coalition; bony union of the subtalar arthrodesis occurred at 6 weeks following surgery. With the 3-portal technique, a safe and time-efficient arthroscopic subtalar arthrodesis can be performed even in cases with limited subtalar joint space such as in symptomatic talocalcaneal coalition.

C sign for diagnosis of talocalcaneal coalition.

To reevaluate the relevance of the C sign for diagnosis of talocalcaneal coalition. Weight-bearing lateral radiographs of 55 feet with talocalcaneal coalition (patient group) and 55 feet without coalition (control group) were reviewed retrospectively. In the patient group, 36 cases of talocalcaneal coalition were confirmed histologically, and 19 cases that did not require surgery were diagnosed at computed tomography (CT). At CT, absence of talocalcaneal coalition in control subjects was confirmed, and control subjects were individually matched with patients according to sex, age, and the calendar year of the clinic visit. Two observers who were blinded to personal information regarding the subjects assessed the presence of the C sign on randomly presented radiographs. When judgments differed, a third observer made the final judgment. Affected feet were classified according to location (ie, medial, posterior, or diffuse) of the coalition and age (ie, <12, 13-20, >21 years). Sensitivity, specificity, and likelihood ratios of the C sign were calculated, and a second radiologic sign, posterior joint surface irregularity, was also evaluated. Differences in occurrence of the C sign among groups according to age and type of coalition were evaluated with the Fisher exact probability test. Sensitivity and specificity of the C sign for diagnosis of talocalcaneal coalition were 49% and 91%. The positive and negative likelihood ratios were 5.44 and 0.56, respectively. Corresponding sensitivity, specificity, and positive and negative likelihood ratios for the irregularity of the posterior talocalcaneal joint were 71%, 93%, 10.14, and 0.31, respectively. C-sign false-negative findings were more frequent in patients younger than 12 years and in those with posterior coalition. C sign sensitivity obtained in our study was low, which indicated that an absence of the C sign does not negate a diagnosis of coalition.

Rapid prototyping (stereolithography) in the management of intra-articular calcaneal fractures.

The purpose of this study was to evaluate and compare the diagnostic performance of stereolithography vs workstation-based three-dimensional (3D) reformations in intra-articular calcaneal fractures. A total of 30 intra-articular calcaneal fractures were examined using standard radiographs, coronal CT scans, and 2D and 3D reformations. The CT data were transferred to an outside institution, and stereolithograms were produced from photopolymer resin employing a laser beam system. 3D reformations and stereolithograms were analyzed in a blinded fashion by two staff radiologists. Receiver-operating-characteristic (ROC) curves were obtained for six clinically significant fracture components. Standard radiographs, coronal CT scans, and 2D reformations served as the standard of reference. The area under the ROC curves for 3D reformations and stereolithograms were 1.0 and 0.98 for abnormal tuber angles, 0.91 and 0.91 for anterior and middle talo-calcaneal joint involvement, 0. 90 and 0.95 for involvement of the posterior talo-calcaneal joint, 0. 65 and 0.78 for the presence of a lateral bulge, 0.80 and 0.81 for the involvement of the calcaneocuboidal joint, and 0.62 and 0.67 for the presence of a "tongue-type" fracture. No statistically significant difference was demonstrated for the two methods (Wilcoxon signed-rank test, p = 0.138). Based on our results stereolithograms did not prove to be statistically superior to workstation-based 3D reformations. Stereolithograms may still be useful for teaching purposes and for surgical planning at a thinking-efficacy level.

Blood vessels of the sinus tarsi and the sinus tarsi syndrome.

This study describes the arterial and venous blood vessels in the sinus tarsi of a series of nine anatomical specimens and in a traumatically amputated leg, studied by arteriography. The sinus tarsi artery was formed in all cases from anastomoses between various arteries of the lateral region of the foot. These usually included the anterior lateral malleolar, and proximal lateral tarsal arteries; in 70% there was a branch from the distal lateral tarsal artery, and in 30% a branch from the peroneal artery. In all cases, there were anastomoses within the sinus tarsi between the sinus tarsi artery and the canalis tarsi artery, derived from the posterior tibial artery. Whatever its origins, the sinus tarsi artery was the principal supplier of intrasinusal structures and of the talus. There was a large venous plexus in the sinus tarsi, which drained particularly the venous outflow from the talus and the anterior part of the capsule of the posterior talocalcaneal joint to the lateral and medial venous systems of the foot. Posttraumatic fibrotic changes in the wall and surrounding tissue of the veins, causing disturbance of venous outflow and increased intrasinusal pressure, are proposed by the authors as one possible factor in the pathogenesis of the sinus tarsi syndrome.

Resection for symptomatic talocalcaneal coalition

Over a nine-year period, 20 feet with persistently symptomatic talocalcaneal coalition were treated by resection of the bar. The 17 patients were all under 16 years of age. Excellent or good long-term results were achieved in the ten feet in which preoperative coronal CT had shown that the area of coalition measured 50% or less of the area of the posterior facet of the calcaneum. In these feet heel valgus was less than 16 degrees and there were no radiographic signs of arthritis of the posterior talocalcaneal joint. Talar beaking was present in 70% of these feet but it did not impair the clinical result. Fair or poor results were observed in the ten feet in which preoperative CT had shown the area of relative coalition to be greater than 50%. In these feet, heel valgus was greater than 16 degrees and most had narrowing of the posterior talocalcaneal joint and impingement of the lateral process of the talus on the calcaneum.

Biomechanics of the Subtalar Joint Complex

The subtalar joint complex is formed by the posterior talocalcaneal joint and the acetabulum pedis lodging the talar head. The basic motion at the joint is that of male ovoid surfaces moving over female ovoid surfaces and vice versa. The motion generated at the joint is that of flexion-supination-adduction or extension-pronation-abduction. The subtalar motion is generated by the contour and orientation of the articular surfaces and is guided by the intrinsic ligaments: the interosseous talocalcaneal ligament of the canalis tarsi and the cervical ligament. Further support is provided by the extrinsic ligaments: the calcaneofibular ligament and the tibiocalcaneal fascicle of the deltoid ligament. Under tibiotalar vertical loading with internal rotation, the subtalar joint complex is in a close-pack position with maximum talar head surface contact in the acetabulum pedis. The component ligaments of the latter are under maximum tension. The posterior talocalcaneal surfaces are interlocked laterally.

The stabilizing role of the lateral ligament complex around the ankle and subtalar joints.

The stabilizing role of various ligaments in the lateral side of the ankle and hindfoot was examined experimentally and sequentially using 10 fresh amputated lower limbs. The anterior talofibular ligament contributed to ankle stability in plantarflexion and the calcaneofibular, the fibulotalocalcaneal, and posterior talofibular ligament in all positions. The lateral root of the inferior extensor retinaculum contributed to subtalar stability in neutral and dorsiflexion. The calcaneofibular, fibulotalocalcaneal, and cervical ligaments and the ligament of the anterior capsule of the posterior talocalcaneal joint and the interosseous ligaments contributed to subtalar stability in all positions. The subtalar joint accounted for upward of 50% of ankle/hindfoot inversion after ligament division in the intermalleolar plane.

Computed tomography of intra-articular calcaneal fractures

The increasing number of operations on intraarticular calcaneal fractures created the need for a fast, reproducible method to examine the weight-bearing posterior talo-calcaneal joint. High resolution CT scanning in an almost coronal plane without reformating was done in 25 calcaneal fractures. Joint alignment and fragment dislocation were demonstrated more precisely than would have been possible with conventional studies. Three typical fractures were found: The lambda type, the y type and the comminution type. Follow-up studies showed osteo-arthritis, intraarticular degenerative changes of the articular surface and impingement of personeal tendons as possible causes of pain.