Subtalar Joint Research Articles

Finite element stress analysis of the hindfoot after medial displacement calcaneal osteotomy with different translation distances.

The medial displacement calcaneal osteotomy (MDCO) is one of commonly used procedures to restore the hindfoot alignment of the flatfoot deformity. However, the selection of the amount of translation for MDCO and its biomechanical effect on the hindfoot was rarely reported. This study employs finite element analysis to investigate stress distribution in the hindfoot following MDCO across varying translation distances. An adult-acquired flatfoot deformity (AAFD) finite element (FE) model consisting of 16 bones, 56 ligaments, and soft tissues was used. MDCO procedure was simulated with the translation distance of 0mm, 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, and 14mm. Contact pressure on the plantar surface, the articular surface of the tibiotalar joint and the subtalar joint, and von Mises stress on the resection surface of the calcaneus under different translation distances were analyzed and compared. Results showed the MDCO reduces 12.46 to 33.32% peak contact pressure on the plantar surface, the tibiotalar joint, and the posterior facet of the subtalar joint, and shifts pressure from lateral to medial. But the difference in peak pressure for different translation distances larger than 4mm was small. The MDCO also reduces the stress on the distal calcaneal resected surface. The study highlights the use of patient-specific computational modeling for preoperative plans.

Dysfunction of the Windlass Mechanism Is Associated with Hallux Rigidus: A Case-Control Study.

The cause of hallux rigidus remains controversial. However, it is assumed that dysfunction of the windlass mechanism and metatarsus primus elevatus play a role in the pathology. Three-dimensional (3D) computed tomography (CT) imaging is ideal for analysis of movements of the foot, which involve 3D and rotational motion. The purpose of the present study was to compare the windlass mechanism in healthy normal feet with that in feet with hallux rigidus by 3D CT imaging. A total of 17 feet with hallux rigidus and 21 normal feet were selected. Hallux rigidus was classified as grade 1 or 2 with use of the Coughlin and Shurnas system. CT imaging was performed during weight-bearing and non-weight-bearing with the first metatarsophalangeal joint in a neutral position or in 30° of dorsiflexion. We measured the rotation of each joint and the height of the navicular during dorsiflexion and weight-bearing. We also compared changes in the tarsometatarsal joint and metatarsus primus elevatus in the neutral position between the non-weight-bearing and weight-bearing conditions. During dorsiflexion, there were significant differences between the 2 groups in eversion and adduction at the talonavicular and talocalcaneal joints (p < 0.05), with less movement of bones in the hallux rigidus group. There was a significantly greater increase in height of the navicular in the control group than in the hallux rigidus group (1.2 ± 0.6 mm versus 0.7 ± 0.6 mm; p = 0.02). There was also a significant difference in metatarsus primus elevatus during the non-weight-bearing and weight-bearing conditions (p < 0.01). Hallux rigidus restricts the movement of the Chopart joint and hindfoot associated with dorsiflexion of the first metatarsophalangeal joint, suggesting an association between hallux rigidus and windlass mechanism dysfunction. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Sanders IV Calcaneus Fracture Treated with Open Reduction and Internal Fixation with a Moldable Plate: A Case Report

Introduction: Calcaneus fractures are the most common tarsal bone fractures, affecting patients quality of life due to osteoarthrosis and a rigid gait. Management must be individualized based on fracture line characteristics, physical activity, and patient life expectancy. Clinical case: A 70-year-old Mexican woman with a history of osteopenia fell, imaging showed traces of a multi-fragmentary fracture, including involvement of the subtalar joint and widening and displacement of the posterior tuberosity of the calcaneus. Open surgery was scheduled 72 hours later, and the patient underwent early mobilization of the ankle, knee, and hip without support. Discussion: The calcaneus is an irregular bone that supports 50% of the forces in the foot during ambulation and standing, resulting in significant deficits after an injury. The surgical management of calcaneal fractures has been criticized for its sequelae, poor functional results, and associated risks. The best management for complex calcaneal fractures is open reduction with primary arthrodesis of the subtalar joint, resulting in a rigid, non-painful foot with adequate mobility. Conclusion: Calcaneal fractures are challenging to manage due to their high complexity and frequency. With advances in preoperative, transoperative, and post-surgical care, traditional methods can be satisfactory. However, infrequency and complexity make it difficult to define specific management definitively.

Morselized Femoral Head Impaction Bone Grafting of Large Defects in Ankle and Hindfoot Fusions.

Ankle and hindfoot fusion in the presence of large bony defects represents a challenging problem. The purpose of this study was to evaluate outcomes of patients who underwent ankle-hindfoot fusions with impaction bone grafting (IBG) with morselized femoral head allograft to fill large bony void defects. This was a 3-center, retrospective review of a consecutive series of 49 patients undergoing ankle or hindfoot fusions with femoral head IBG for filling large bony defects. Union was assessed clinically and radiologically with radiography or computed tomography. Graft stability/collapse was identified on radiographs as loss of graft height across the fusion interface. Indications included 35 failed total ankle arthroplasty, talar osteonecrosis and collapse (7 patients), failed ankle fusion (4 patients), trauma with bone loss or fracture nonunion (1 patients), and other (2 patients). Tibiotalocalcaneal (TTC) fusion was performed in 36 (73%) patients and ankle (TT) fusion in 13 (27%). Mean age was 59.3 (19-78) years. Mean follow-up was 22.9 ± 8.3 months. Eighteen percent were smokers. Mean depth of the bone defect was 35.2 ±8.7 mm, and mean volume of the defect was 62.2 ±5.8 cm3. Symptomatic nonunion rate was 14% (7/49). The mean time to radiologic union was 7.6 ±3.2 months. Complete radiologic union rate occurred in 73% (36/49). Eight TTC fusion patients (22.2%) united at the tibiotalar joint but not at the subtalar joint, of which 6 were asymptomatic. There was no graft collapse, even in patients developing nonunion, with all patients maintaining bone incorporation and leg length. Impaction of morselized femoral head allograft can fill large bony voids around the ankle or hindfoot during fusion, with rapid graft incorporation and no graft collapse despite early loading. This technique offers satisfactory and comparable union outcomes without limb shortening or expensive custom 3D-printed metal cages.

Three-Plane Calcaneal Osteotomy With Joint Preservation vs Subtalar Arthrodesis to Treat Painful Calcaneal Fracture Malunions.

Calcaneal fracture malunion (CFM) commonly occurs with multiple pathologic changes and progressive pain and difficulty walking. The purpose of this study was to propose a modified 3-plane joint-preserving osteotomy for the treatment of CFM with subtalar joint incongruence, and to compare its efficacy to subtalar arthrodesis. A retrospective comparative analysis of the data of 56 patients with CFM admitted from January 2017 to December 2022 was performed. Twenty-six patients were in the osteotomy group and 30 in the arthrodesis group. Computed tomographic (CT) scans were used for measurement of the intraarticular steps. Radiologic parameters, visual analog scale (VAS) score for pain, 12-Item Short Form Health Survey (SF-12) mental component summary (MCS) and physical component summary (PCS) scores were compared between the 2 groups of patients to assess the outcome preoperatively and at last follow-up, which averaged 22.6 ± 3.6 months and 27.6 ± 3.6 months for the osteotomy and arthrodesis groups, respectively. Improvements in pain, function, and overall quality of life were obtained in both groups compared with the preoperative values at last follow-up. The VAS and SF-12 scores were similar between the groups at the last follow-up. In the osteotomy group, the average CT scan-measured intraarticular step-offs were significantly reduced from 3.7 ± 1.2 mm to 0.9 ± 0.3 mm. The osteotomy group showed improvement in pronation and supination range of motion (ROM) of the feet (P < .01). The correction of the ankle height and Meary angle were slightly better in the osteotomy group. In this short-term follow-up study, good results were achieved in both joint-preserving osteotomy and subtalar arthrodesis groups for the treatment of CFM with subtalar joint incongruence. The osteotomy group preserved the subtalar joint and achieved improvements in pronation and supination ROM.

Cadaveric Study Evaluating the Potential for Hindfoot Endoscopy and Flexor Hallucis Longus Tendoscopy Using a 1.9-mm Diameter Needle Arthroscope.

Hindfoot endoscopy is an effective treatment for posterior ankle impingement syndrome (PAIS) and flexor hallucis longus (FHL) tendon disorders. However, FHL tendoscopy, especially from the posteromedial portal, carries a risk of tibial nerve damage. A needle-arthroscopic system with a 1.9-mm-diameter arthroscope, a semirigid frame, and a 0-degree direction of view has been introduced. This study aimed to evaluate the efficacy and safety of this system in visualizing and reaching significant structures in hindfoot endoscopy and FHL tendoscopy through the posteromedial and posterolateral portals using a cadaveric model. The 1.9-mm-diameter arthroscopic system (NanoScope, Arthrex) was used to perform hindfoot endoscopy in 6 human donor ankles (3 pairs). The arthroscope tube is 9.5 cm long, semirigid, and has an outer diameter of 1.9 mm, a 0-degree direction of view, and a 120-degree field of view. Posteromedial and posterolateral portals were established. Visualization and operative reach were recorded, including the posterolateral talar process, posterior talofibular ligament, intermalleolar ligament, subtalar joint, and FHL tendon. The neurovascular bundle and FHL tendon were examined for kinks or damage. All significant structures were successfully visualized in all specimens. The wide 120-degree field of view facilitated adequate visualization of all structures. In all specimens, the FHL tendon was visualized from the ankle joint to the knot of Henry (zones 1 and 2), and the flexor digitorum longus tendon was observed via both portals. There were no signs of neurovascular damage from either the posterolateral or posteromedial portals. In this cadaver experiment without known pathology, use of a 1.9-mm-diameter needle-arthroscopy with a 0-degree direction of view provided effective visualization of all significant structures in treating PAIS and FHL tendon disorders. It appears that FHL tendoscopy can be performed from the level of the ankle joint to the knot of Henry via both the posterolateral and posteromedial portals.

Human in vivo talocrural contributions to ankle joint complex kinematics during walking, running, and hopping.

The human ankle joint complex, consisting of calcaneus, talus, and tibia, is often simplified as a single functional ankle joint, neglecting the motion of the talus. Understanding the individual contributions of the talus and calcaneus is crucial for comprehending ankle joint complex function in healthy populations, and alterations in function that may exist in clinical conditions. To achieve accurate bone kinematics, high-resolution biplanar videoradiography was used with participants engaged in walking and running (n=9) and hopping (n=9) with no overlap in participants. The rotation axes for the calcaneus and talus were analysed relative to the tibia over the ankle joint dorsi-/plantar flexion phases. Contributions of the talocrural joint to overall ankle joint complex function were measured by comparing the range of motion (talus relative to calcaneus). Most of the sagittal plane motion in the ankle joint complex (80%) occurred in the talocrural joint, with the subtalar joint contributing 20%. Rotation of the calcaneus about the tibia dominated frontal and transverse plane motion during hopping. Although surprisingly large ranges of talus motion were also observed in these planes (>5deg), indicating notable inter-subject variability and that the talocrural joint is not a simple hinge joint. The study highlights the importance of directly quantifying talus motion to understand ankle joint complex function. The results showed opposing talus and calcaneus movements for many participants during different locomotor tasks, which may influence the magnitude and distribution of subtalar joint loading. In addition, the large out-of-sagittal plane movements and inter-subject variability in talus and calcaneus motion may further emphasize the need for personalised models to investigate treatments for ankle pathologies.

High-heeled Shoes Increase Motion of the Talocrural Joint While Limiting the Subtalar Joint

High-heeled Shoes Increase Motion of the Talocrural Joint While Limiting the Subtalar Joint

Union rates following power rasp joint preparation for foot and ankle arthrodesis: A retrospective study of 418 fusions.

Joint arthrodesis is a very common surgical approach in foot and ankle surgery at various anatomic levels. Several techniques have demonstrated the ability to provide successful fusion with appropriate preparation of the joint in question. With that in mind, the joint preparation, regardless of approach or instrumentation, is consistently the most time-consuming. Additionally, this step is prone to eventual complications like shortening with saw cuts or inadequate preparation with curettes and osteotomes alone, not to mention the persistent threat of non-union as is the case with any osteotomy or arthrodesis. Power rasp instrumentation presents a potential alternative for the surgeon to not only improve operating room efficiency, but also provide fast, reproducible, and adequate joint preparation thereby yielding excellent union rates. This study retrospectively analyzed 418 total arthrodesis attempts performed on 198 patients. Procedures included Lapidus bunionectomy/1st tarsometatarsal joint (TMTJ) fusion, midfoot fusions involving more than one TMTJ, isolated subtalar joint fusions (STJ), isolated talonavicular fusions (TNJ), and triple arthrodesis (STJ, TNJ, CCJ). The procedures were performed at a single institution with power rasp joint preparation (PJRP) as the primary tool for debridement of all cartilage from the articular surfaces of the joint in question. Minimum follow-up was 12 months. Radiographic union was defined on X-rays with osseous bridging and trabeculation across the fusion site using standard weightbearing foot radiographs taken at 3-, 6-, and 12-month intervals postoperatively. Four- and one-half percent of all arthrodesis attempts went on to develop a radiographic non-union after 12 months (19/418). This study demonstrates excellent overall union rates using a simple device that provides ease of surgeon use, minimal risk of non-union, and time-cost efficiency for providers, patients, and facilities alike.

Painful Flexible Flatfoot Deformity: A Description of Posterolateral Ankle Trigger Point for Pain.

Background Flexible flatfoot deformity may be painful, and it is often difficult to pinpoint one painful area. Considerable variability of symptoms and areas of pain are noted in this condition. This study aimed to identify a reproducible area of pain and tenderness in these types of feet, implying a painful flatfoot. Methodology This study included 35 patients, comprising 23 males and 12 females, with 66 painful flexible flatfoot deformities representing the study group. The average age was 7.8 years (range = 2-15). In total, 31 patients had bilateral pain, and four patients had unilateral pain. The control group included 20 age-matched patients with normal painless feet. Results In 28 patients, pain was non-localized in the lower extremity. Overall, seven patients had non-localized pain in the foot and could not identify a point of maximal tenderness. A new trigger point for pain was identified in all patients, 1.5-2 cm below and 1.5-2 cm posterior to the tip of the lateral malleolus, well behind the peroneal tendons. No pain was reported by the control group. Conclusions A new constant trigger point for pain was identified in all patients with painful flatfoot deformity. It is hypothesized to be due to the overloading of the posterolateral corner of the talocalcaneal joint or impingement on the calcaneofibular ligament secondary to the heel valgus. We believe that the presence of this trigger point will help clinicians confirm flatfoot deformity as the source of pain, adding another tool in the evaluation and diagnosis of this condition.

The Effect of Clinical Exercise Training on Plantar Pressure, the Subtalar Joint, and the Gait Cycle in Pregnant Women: Randomized Clinical Trial.

Background/Objectives: This study aims to examine the effects of clinical exercise training on foot plantar pressure, the subtalar joint, and the gait cycle during pregnancy. Methods: The study was planned as a randomized, controlled, and single-blind study. Participants' demographic information, obstetric evaluation, physical activity level, fall history, and pain evaluation were recorded. Foot plantar pressure, the subtalar joint, and the gait cycle were measured through pedobarography at Gait Laboratory. The control group was recommended walking. Clinical exercise training was given to the study group 2 days a week for eight weeks. Evaluations were made on day 0 and the day corresponding to the end of week 8. Results: The study was completed with 50 people in the study group (age: 29.7 ± 3.8 years) and 51 in the control group (age: 29.1 ± 6.1 years). As a result of the parametric and non-parametric tests performed before and after the exercise, it was observed that there was a statistically significant difference between the two groups in weight, BMI, pain score, static plantar pressure, dynamic plantar pressure, subtalar joint flexibility, duration of the walking period, and multistep walking speed (p < 0.01). The two groups had a significant difference only in the dominant midfoot plantar pressure (p > 0.05). Conclusions: According to our research, weight control and pain relief are observed in women who engage in clinical exercise in the second trimester of pregnancy; plantar pressure and subtalar joint flexibility are preserved, the walking period does not increase, and the multistep walking speed can be maintained after eight weeks.

Impact of Contralateral Hemiplegia on Lower Limb Joint Kinematics and Dynamics: A Musculoskeletal Modeling Approach

This study investigates the biomechanical differences between typically developed (TD) individuals and those with contralateral hemiplegia (CH) using musculoskeletal modeling in OpenSim. Ten TD participants and ten CH patients were analyzed for joint angles and external joint moments around the three anatomical axes: frontal, sagittal, and transverse. The analysis focused on hip, pelvis, lumbar, knee, ankle, and subtalar joint movements, leveraging MRI-derived bone length data and gait analysis. Significant differences (p &lt; 0.05) were observed in hip flexion, pelvis tilt, lumbar extension, and ankle joint angles, highlighting the impact of hemiplegia on these specific joints. However, parameters like hip adduction and rotation, knee moment, and subtalar joint dynamics did not show significant differences, with p &gt; 0.05. The comparison of joint angle and joint moment correlations between TD and CH participants highlights diverse coordination patterns in CH. Joint angles show significant shifts, such as HF and LR (−0.35 to −0.97) and PR and LR (0.22 to −0.78), reflecting disrupted interactions, while others like HR and LR (0.42 to 0.75) exhibit stronger coupling in CH individuals. Joint moments remain mostly stable, with HF and HA (0.54 to 0.53) and PR and LR (−0.51 to −0.50) showing negligible changes. However, some moments, like KA and HF (0.11 to −0.13) and PT and KA (0.75 to 0.67), reveal weakened or altered relationships. These findings underscore biomechanical adaptations and compensatory strategies in CH patients, affecting joint coordination. Overall, CH individuals exhibit stronger negative correlations, reflecting impaired coordination. These findings provide insight into the musculoskeletal alterations in hemiplegic patients, potentially guiding the development of targeted rehabilitation strategies.

Effect of three-week exercise program on muscle strength and joint mobility in patients with diabetic polyneuropathy: Randomized controlled trial.

Limited joint mobility is the proven risk factor for diabetic foot ulceration when present in the subtalar and first metatarsophalangeal joints. Evidence shows that a foot-related exercise program, combined with a health-promoting program, can improve the signs and symptoms of diabetic polyneuropathy, enhance gait, restore mobility in the foot and ankle joints, redistribute pressure while walking, and increase foot strength and function. As a result, these exercise programs can help mitigate the risk factors for diabetic foot ulceration. To determine the effect of supervised stretching, strengthening, functional and walking exercises on joint mobility and muscle strength in patients with diabetic polyneuropathy. This was a randomized controlled trial conducted in a tertiary hospital. The study included 82 participants allocated into the intervention group (alpha-lipoic acid and exercise on 15 consecutive therapeutic days, n = 42) and control group (alpha lipoic acid only, n = 40). Muscle strength included dorsal and plantar flexors dynamometry and strength score, while range of motion included ankle, subtalar and first metatarsophalangeal joint goniometry. Change of motion range was significantly higher in the intervention group compared to the control group regarding ankle joint on day 15 (9.9 ± 7.2 vs 0.1 ± 3.3; P = 0.006) and month 6 (2.8 ± 7.3 vs -0.9 ± 4.1; P < 0.001), subtalar joint on day 15 (7.5 ± 5.1 vs -0.25 ± 2.25; P < 0.001) and month 6 (3.9 ± 6.4 vs -0.13 ± 3.49; P < 0.001). Change in dorsal flexors was significantly higher in the intervention group compared to the control group on day 15 (2.62 ± 1.69 vs 0.10 ± 1.35; P < 0.001) and month 6 (0.66 ± 2.38 vs -0.75 ± 1.94; P = 0.004) as well as plantar flexors on day 15 (3.3 ± 1.6 vs 0.3 ± 1.5; P < 0.001) and month 6 (1.8 ± 2.2 vs -0.9 ± 2.1; P < 0.001). Muscle strength score change was significantly lower in the intervention group compared to the control group on day 15 (-1.45 ± 1.42 vs -0.03 ± 0.16; P < 0.001) and month 6 (-1.17 ± 1.53 vs 0.20 ± 0.56; P < 0.001). Exercise in combination with alpha-lipoic acid can improve joint mobility, as well as strength of the foot and lower leg muscles in patients with diabetic polyneuropathy.

Open versus arthroscopic fusion of the subtalar joint: a randomized controlled trial.

Our primary aim was to compare the early complication rate (< 6 weeks postoperatively) after open or arthroscopic fusion of the subtalar joint. Secondary outcomes included late complications (> 6 weeks postoperatively), function, pain, and patient satisfaction. In this prospective randomized controlled trial, patients listed for subtalar joint fusion were included and randomized for open or arthroscopic fusion. Complications were assessed at scheduled visits at 2 and 6 weeks, 3, 6, and 12 months postoperatively. Functional scores, pain scores, and patient satisfaction were assessed at 3, 6, and 12 months postoperatively, and PROMS at baseline (preoperatively), 3, 6, and 12 months postoperatively. The scores were compared over time between the groups using Fisher's exact test and linear mixed models. 51 patients were included between 2013 and 2020, of whom 25 were allocated to open and 26 to arthroscopic fusion. 3 early complications (2 sural nerve lesions, 1 infection) occurred in the open fusion group (12%; 95% confidence interval [CI] 3-32) and 3 (2 wound healing problems, 1 screw exchange) in the arthroscopic group (12%; CI 3-31). Late complications included screw removal (n = 5) in the open fusion group versus screw removal (n = 5), non-union (n = 2), bony prominence/calcification removal (n = 1), sural nerve lesion (n = 1), lesion of the calcaneal branch of the tibial nerve (n = 1), complex regional pain syndrome type II (n = 1), and secondary plantar fasciitis (n = 1) in the arthroscopic fusion group. No superiority of arthroscopic over open fusion was found regarding early (P = 1.0) and late complications (P = 0.2), function and pain scores, and patient satisfaction over 12 months Conclusion:Arthroscopic fusion did not result in fewer early complications compared with open fusion. Secondary outcomes did not differ significantly between the approaches.

Characteristics That Predict Psoriatic Arthritis by the Classification Criteria for Psoriatic Arthritis in Patients With Juvenile Idiopathic Arthritis 18 Years After Disease Onset.

The purposes of this study were to assess the clinical characteristics of patients with juvenile idiopathic arthritis (JIA) who fulfill the ClASsification criteria for Psoriatic ARthritis (CASPAR) 18 years after disease onset in a population-based setting and to identify features likely to predict psoriatic arthritis (PsA). Patients with JIA from defined geographic regions of Denmark, Finland, Norway, and Sweden with disease onset from 1997 to 2000 were enrolled prospectively and followed up for 18 years. Clinical, laboratory, and heredity data for psoriasis were collected. Patients were classified according to the International League of Associations for Rheumatology (ILAR) criteria at baseline, and we applied ILAR and CASPAR criteria at 18 years. Logistic regression was performed to study the effects of JIA-related characteristics and heredity for psoriasis on being classified for PsA. Among the 510 patients enrolled, 434 participated in the 18-year follow-up, 28 (6.5%) met the ILAR criteria, and 41 (9.4%) fulfilled the CASPAR criteria. Patients with wrist or subtalar joint involvement at onset had higher odds of being classified with PsA at 18 years (odds ratio [OR] 3.3, P = 0.02 and OR 12.9, P = 0.01, respectively). Presence of psoriasis, nail abnormalities, or dactylitis showed significant association with development of PsA (OR 20.2, P < 0.001; OR 11.6, P = 0.002; and OR 43.4, P < 0.001, respectively). CASPAR criteria identify more patients with PsA compared with ILAR criteria and may better capture the heterogeneous nature of the disease. Presence of psoriasis and dactylitis at disease onset were the strongest predictors for the development of PsA. Further studies on the utility of CASPAR criteria in patients with JIA are needed.

Mid-term results of intra-articular calcaneal fractures treated with minimally invasive two-point distractor

Summary Background Displaced intra-articular calcaneal fractures are a complication-ridden injury to treat and there are various treatment techniques to address this injury. The aim of this study was to evaluate the mid-term outcome of a percutaneous two-point distractor technique in patients with displaced intra-articular calcaneal fractures. Methods A retrospective data analysis of patients with intra-articular calcaneal fractures treated in a level 1 trauma center was conducted. The patients were subsequently invited for a follow-up visit to assess the mid-term outcome. The Böhler’s and Gissane’s angles, the American Orthopaedic Foot &amp; Ankle Society hindfoot score, the Maryland foot score and a visual analog scale for pain were measured preoperatively and postoperatively and after at least 6 years to assess the radiological and functional outcome. Results Of the patients 59 completed the study with a mean follow-up of 76 months after surgery. The mean American Orthopedic Foot and Ankle Society hindfoot score at the last follow-up visit was 81, the mean Maryland foot score was 78. There were three cases (5%) of superficial wound complications and secondary arthrodesis of the subtalar joint was performed in five patients (8%). Conclusion The low rates of postoperative infections and secondary arthrodesis in this study underline the good to excellent mid-term functional results for a minimally invasive technique.

Effects of additional weight-bearing on the in vivo kinematics of the human ankle joint complex during walking

Studies focusing on the kinematics of the ankle joint complex (AJC) have long been a key area of interest for biomechanists and orthopedic surgeons. However, it is not clear how additional weight-bearing walking affects the motion of the AJC compared to walking with a normal body weight (BW) or what adjustments the AJC would instinctively make to accommodate the additional load. To address this gap in knowledge, advanced dynamic biplane radiography combined with a model-based 2D-3D tracking technique was employed to elucidate the inherent kinematics of the AJC during the stance phase while walking with and without additional weight-bearing. It was found that walking with additional 50% body weight (BW + 50%) resulted in a greater dispersion of instantaneous axes of rotation in the talocrural and subtalar joints during the stance phase of gait. The talocrural joint is more plantarflexed and anteriorly translated during the early and late stance phases than during the midstance phases, which suggests that additional weight-bearing affects the stability of the AJC. Moreover, walking with BW + 50% showed that the center of rotation of the talocrural joint was positioned more superiorly and posteriorly during the foot flat to heel-off phase. This, accordingly, increases the ankle-foot gear ratio and the force of the dorsiflexors.

Direct Anatomical Reconstruction of the Achilles Tendon and Its Application for Surgical Treatment of Acute Achilles Tendon Ruptures

Background/Objectives: Acute ruptures of the Achilles Tendon (AT) are common injuries in the active population, in particular among men aged 30 to 50. Full functional recovery after this kind of injury is long and challenging and nowadays there is no universal “gold standard” strategy when dealing with them. Methods: When it comes to surgical treatment, various techniques have been described: in case of a typical lesion at the midportion of the tendon (which is the most common type), the basic principle of surgical repair is the end-to-end suture of the tendon stumps. The AT (“calcaneal tendon” according to the International Anatomical Terminology) is the strongest tendon of the human body, it is the conjunct tendon of the two Gastrocnemii Muscles and the Soleus Muscle and has a well-recognizable twisted structure: the subtendon from the Medial Head of the Gastrocnemius attaches postero-laterally on the calcaneal tendon footprint, the subtendon from the Lateral Head of the Gastrocnemius attaches antero-laterally and the subtendon from the Soleus attaches medially, therefore creating a 90° twist of the tendon structure. Results: the twisted structure of the human AT is of central importance to its biomechanics, since it gives the tendon a higher resistance to deformation and concurs in supination of the subtalar joint during gait. Conclusions: given the abovementioned anatomical and biomechanical premises, we believe that the restoration of the subtendons anatomy can lead to a better functional recovery of the Triceps Surae—Achilles Tendon complex, therefore we recently decided to adopt for open surgical repair the Direct Anatomical Reconstruction of the Achilles Tendon, which we describe in the present article.

Biomechanical conditions of subtalar joint arthrodesis with calcaneal locking nail: A probabilistic numerical study.

Subtalar joint arthrodesis is primarily indicated for advanced osteoarthritis, hindfoot deformity, and/or instability. During the first 6-10 weeks after surgery, there is an intermediary structurally weaker state before complete bony fusion of the calcaneus and talus occurs. Loading of the foot can lead to mechanical stresses and relative movements in the former joint gap, which can impede the fusion process. The objective of this study was to examine the mechanical healing conditions for a subtalar arthrodesis with a calcaneal locking nail. A probabilistic finite element model of the subtalar joint with a calcaneal locking nail was created to represent the foot post-surgery that accounts for the uncertainty of the material properties. The model differentiates between cortical and cancellous bone and includes non-linear contact definitions in the subtalar joint. Multiple loading scenarios, including hindfoot inversion/eversion, were simulated to determine bone and implant stresses. Utilizing local articular coordinate systems, a displacement analysis was established to separate normal and tangential components and account for their separate effects. The loading of the locking nail was assessed through section moments. Under inversion/eversion loading, the area near the locking screws and upper end of the nail experienced the highest stresses. The maximum stresses in cortical and cancellous bone were 112±8.3 MPa and 2.1±0.2 MPa, respectively. The comparison of the von Mises and maximum principal stresses for the bones showed a load case dependency with strong effect on tensile loading states. The proposed method for the analysis of relative displacement in the local articular coordinate systems showed joint regions exhibiting normal and tangential movements that changed with the considered loading states. It was found that tangential displacements of up to 0.19 mm are related to the torsional loading of the calcaneal locking nail, which is connected to the corresponding torsional stiffness of the implant and its fixation in the calcaneus and talus. Normal displacements in the joint gap of up to -0.18 mm can be shown to be governed by the bending moments acting on the calcaneal locking nail, which are linked to the nail's bending stiffness. The ratio of tangential and normal displacement in the critical inversion configuration was determined to be -1.1. Inversion and eversion loads can lead to significant mechanical loading of the bones and to bending and torsional loading of the locking nail. The bending leads to normal displacements in the articular gap. Torsions can lead to significant tangential displacements that have been shown to promote non-union instead of bony fusion.

Risk Factors for Chronic Syndesmotic Instability After the First Episode of Acute Ankle Sprain: A Cross-Sectional Study of 356 Cases.

Chronic syndesmotic instability (CSI) can be associated with severe long-term pain and disability. This study aimed to investigate the risk factors associated with the development of CSI in patients who underwent conservative treatment after the first episode of acute ankle sprain (AAS) that did not result in a satisfactory outcome. We retrospectively analyzed the clinical data of patients who underwent ankle arthroscopy for suspected CSI between January 2020 and September 2023. The patients were divided into the instability and stability groups based on the syndesmotic space width measured under arthroscopy, with 3 mm as the critical value. Demographic, arthroscopic, and imaging information such as the anterior talofibular ligament (ATFL), calcaneofibular ligament, posterior talofibular ligament (PTFL), anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), deltoid ligament (DL), interosseous membrane, height of the syndesmotic fluid, injuries of the talus, calcaneus, tibia, and fibula, effusion of the tibiotalar and talocalcaneal joints, fibular morphology, and fibular incisura features, were recorded. Univariate and multivariate analyses were performed successively to identify the risk factors. Of the 356 patients, 102 developed CSI after the first episode of AAS. In the multivariate analysis, development of CSI was associated with 5 clinical factors: DL injury (odds ratio [OR] 7.453, 95% CI 3.007-18.471; P < .001), positive bandage-binding test (OR 7.196, 95% CI 2.942-17.599; P < .001), grade 2 to 3 injury of the PITFL (OR 2.727, 95% CI 1.044-7.124; P = .041), positive squeeze test (OR 2.455, 95% CI 1.045-5.770; P = .039), and body mass index (BMI) (OR 1.306, 95% CI 1.121-1.522; P < .001). Five key factors were associated with CSI development in patients who underwent conservative treatment after the first episode of AAS that did not result in a satisfactory outcome: DL injury, positive bandage-binding test, grade 2 to 3 injury of the PITFL, positive squeeze test, and BMI.