Determining the changes in morphology and loading status following medial displacement calcaneal osteotomy for flatfoot using patient-specific finite element models.

Medial displacement calcaneal osteotomy (MDCO) is the standard procedure for flatfoot. We investigated the effect of MDCO on the foot using a finite element analysis. Foot models were created from computed tomography data of 8 patients with flat feet. MDCO was performed on each model with bone translation distance of 4, 8, and 12 mm. The morphological changes, plantar pressures, and stress percentage on the talocrural and subtalar joints were evaluated before and after surgery. Morphological evaluation showed improvement in the medial longitudinal arch. The stress percentage of plantar pressure in the medial area decreased, and the stress percentage of plantar pressure in the mid- and lateral forefoot area increased. At the talocrural joint, the medial and middle stress percentage increased, while the lateral and posterior stress percentage decreased. In the subtalar joint, the stress percentage in the middle subtalar joint increased and that in the posterior subtalar joint decreased. Within the posterior subtalar joint, the anterior and medial stress percentage increased, while the posterior and lateral stress percentage decreased. Preoperative simulation using the finite element analysis may be useful in understanding postoperative morphological changes and loading conditions to perform patient-specific surgery.

The Relationship Between Calcaneofibular Ligament Injury and Ankle Osteoarthritis Progression: A Comprehensive Analysis of Stress Distribution and Osteophyte Formation in the Subtalar Joint.

BACKGROUND: Ankle osteoarthritis (OA) mainly arises from trauma, particularly lateral ligament injuries. Among lateral ligament injuries, ankles with calcaneofibular ligament (CFL) injuries exhibit increased instability and can be a risk factor ankle OA progression. However, the relationship between CFL injury and OA progression remains unclear. Therefore, this study aims to assess the relationship between CFL injuries and ankle OA by investigating stress changes and osteophyte formation in subtalar joint. METHODS: We retrospectively reviewed the magnetic resonance imaging (MRI) and plain radiographic evaluations of 100 ankles of 91 patients presenting with chronic ankle instability (CAI), ankle OA, or other ankle conditions. The association between CFL injuries on the oblique view of MRI and the severity of ankle OA (based on Takakura-Tanaka classification) was statistically evaluated. Additionally, 71 ankles were further subjected to CT evaluation to determine the association between the CFL injuries and the Hounsfield unit (HU) ratios of the subtalar joint and medial gutter, and the correlation between the subtalar HU ratios and osteophyte severity were statistically evaluated. RESULTS: CFL injury was observed in 35.9% (14/39) of patients with stage 0, 42.9% (9/21) with stage 1, 50.0% (10/20) with stage 2, 100% (9/9) with stage 3a, and 90.9% (10/11) with stage 3b. CFL-injured ankles exhibited higher HU ratios in the medial gutter and lower ratios in the medial posterior subtalar joint compared to uninjured ankles. A negative correlation was observed between medial osteophyte severity and the medial subtalar joint HU ratio. CONCLUSION: Our findings suggest that CFL injuries are common in severe ankle OA impairing the compensatory function of the subtalar joint through abnormal stress distribution and osteophyte formation.

Sustentaculum fracture fixation with lateral plate or medial screw fixation are equivalent.

BACKGROUND: Fixation of sustentaculum tali fractures is important to maintain the biomechanical function of the subtalar joint. A common method of fixation is securing the sustentacular fragment by way of a laterally based locking plate (LP). A medial approach with a single screw (MS) has been proposed as an alternative method of fixation. METHODS: Five pairs of formalin-preserved cadaveric ankles with the subtalar joint and interosseous ligaments intact ("osseous cadavers") and four pairs of fresh-frozen cadaveric ankles with soft-tissue preserved dissected from mid-tibia down ("soft tissue cadavers") were used in the study. The left ankle was randomly assigned to one of the two fixation methods (LP or MS), while the right ankle was the opposite. These same steps for fixation were repeated for six synthetic ankle models. All models were loaded with a body mass of 80 kg. Statistical differences between LP and MS stiffness were determined using a paired t-test in cadavers and un-paired t-tests in synthetic ankles. RESULTS: For osseous cadaveric ankles, LP demonstrated a mean stiffness of 232.95(SD: 59.96) N/mm, while MS was 239.72(SD:131.09) N/mm (p = 0.9293). For soft tissue cadaveric ankles, LP mean stiffness was 133.58(SD:37.84) N/mm, while MS was 134.88(SD:20.75) N/mm (p = 0.9578). For synthetic ankles, LP mean stiffness was 220.40(SD:81.93) N/mm, while MS was 261.50(SD:100.21) N/mm (p = 0.6116). CONCLUSIONS: Across all three models, there was no significant difference between LP and MS methods. Retrospective observational studies are recommended to assess patient outcomes from each of the methods.

Hindfoot joint kinematics analysis after the resection of talocalcaneal coalition.

BACKGROUND: The subtalar joint movement between the talus and calcaneus is restricted in patients with talocalcaneal coalition (TCC). When the motion of the subtalar joint is restricted, shock absorption in the foot decreases, leading to pain during walking. Resection methods to maintain subtalar motion by removing abnormal unions have been proposed. The purpose of this study was to analyze the joint kinematics of patients who underwent TCC resection and to quantitatively evaluate the results of the surgery based on the measured kinematics. METHODS: Joint kinematics of five patients with TCC were obtained using a biplane fluoroscopic imaging system and an intensity-based two-/three-dimensional registration method. The joint kinematics of the tibiotalar and subtalar joints and the tibiocalcaneal motion during the stance phase of walking were obtained. From the kinematics of the hindfoot joints, the inversion/eversion range of motion (ROM) of the patients before and after resection was statistically analyzed using the Wilcoxon signed-rank test to test whether TCC resection improved the ROM. RESULTS: During the loading response period, the eversion ROM of the subtalar joint and tibiocalcaneal motion significantly increased postoperatively. In addition, a significant postoperative increase was observed in the subtalar and tibiocalcaneal inversion ROM during the pre-swing period. SIGNIFICANCE: TCC resection surgery increased the ROM of the subtalar joint, which in turn contributed to the increase in tibiocalcaneal ROM. Increased subtalar and tibiocalcaneal ROM could result in increased shock attenuation and may be a contributing factor to pain relief during walking.

The importance of Böhler's angle in calcaneus geometry: A finite element model study.

OBJECTIVES: Calcaneal fractures are the most common tarsal fractures following a foot-ankle trauma. The Böhler's angle is an important measurable angle before, during, and after surgery. In this study, we aimed to investigate correlation between Böhler's angle, calcaneal strength, and subtalar joint stress using a finite element analysis (FEA). PATIENTS AND METHODS: Between January 2016 and December 2016, computed tomography (CT) scans were used with MIMICS® software for FEA. The ankle and foot of a 23-year-old male person with a height of 180 cm and weighing 80 kg was modeled as reference. Raw coronal CT images were obtained in Digital Imaging and Communications in Medicine format with the resolution of 512X512 pixels and 0.3-mm slice intervals in 135 kV. The structures including tibia, fibula and 26 other bones (talus, calcaneus, cuboid, navicular, three cuneiforms, five metatarsals, and 14 components of phalanges), cartilage and ligamentous tissues were modeled to form ankle joint. After determining Böhler's angle as 35 degrees for the reference model, a fracture line was created on calcaneus. Calcaneus was remodeled with the Böhler's angle of 45, 40, 30, 25, 20, 10, and 0 degrees respectively. All models were transferred to ANSYS software for FEA and the loads on the lower extremities with normal posture were applied on models. RESULTS: Analysis of all models based in the reference model revealed that maximum tension values on calcaneus increased, while the Böhler's angle decreased, indicating a statistically significant difference. The decreased Böhler's angle indicated statistically significantly higher maximum tension values (p=0.04). Action force in subtalar joint was evaluated by comparing with the forces in reference model. The increased Böhler's angle was found to be associated with statistically significantly decreased amount of load on subtalar joint. The decreased Böhler's angle was related to the statistically significantly increased amount of load on subtalar joint. CONCLUSION: Our study results suggest that decreased Böhler's angle increases the possibility of subtalar arthrosis, although overcorrection of the Böhler's angle seems not to increase the risk of subtalar arthrosis.

Clinical and Radiological Outcomes of Subtalar Kalix II Arthroereisis for a Symptomatic Pediatric Flexible Flatfoot.

Background. The purpose of this study is to evaluate functional and radiological outcomes of subtalar arthroereisis in the treatment of symptomatic pediatric flexible flatfeet. Methods. A total of 16 patients (26 feet) were treated with a Kalix II as subtalar motion blocker between 2009 and 2014. Calcaneal pitch (CP) and Meary's angle (MA) were measured on radiographs preoperatively, directly postoperatively, and at follow-up 47 ± 17 (range 19-79) months. Patient satisfaction surveys were used to assess functional outcome and patient satisfaction. Results. Surgery was performed mostly for pain, walking problems, or a combination of both at a mean age of 12.5 ± 1.5 (range 10-15) years. Symptoms were relieved in 62.5% of patients in the postoperative phase and increased to 68.75% at follow-up. A statistically significant increase in CP of 2.8° and decrease in MA of 14.0° was observed directly postoperatively, which persisted during the follow-up period irrespective of Kalix removal. Revision surgery was necessary in 6 cases (23%) because of arthroereisis migration. Conclusion. Subtalar Kalix II arthroereisis significantly reduced clinical symptoms and improved the CP and MA directly postoperatively, which persisted during follow-up, irrespective of Kalix removal. Therefore, subtalar arthroereisis is a considerable intervention to reduce symptoms in children with symptomatic flexible flatfeet.Levels of Evidence: Level IV: Case series.

Consensus for the Indication of Lateral Column Lengthening in the Treatment of Progressive Collapsing Foot Deformity.

RECOMMENDATION: Progressive collapsing foot deformity (PCFD) is a complex 3D deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot supination. Although a medial displacement calcaneal osteotomy can correct heel valgus, it has far less ability to correct forefoot abduction. More severe forefoot abduction, most frequently measured preoperatively by assessing talonavicular coverage on an anteroposterior (AP) weightbearing conventional radiographic view of the foot, can be more effectively corrected with a lateral column lengthening procedure than by other osteotomies in the foot. Care must be taken intraoperatively to not overcorrect the deformity by restricting passive eversion of the subtalar joint or causing adduction at the talonavicular joint on simulated AP weightbearing fluoroscopic imaging. Overcorrection can lead to lateral column overload with persistent lateral midfoot pain. The typical amount of lengthening of the lateral column is between 5 and 10 mm. LEVEL OF EVIDENCE: Level V, consensus, expert opinion. CONSENSUS STATEMENT ONE: Lateral column lengthening (LCL) procedure is recommended when the amount of talonavicular joint uncoverage is above 40%. The amount of lengthening needed in the lateral column should be judged intraoperatively by the amount of correction of the uncoverage and by adequate residual passive eversion range of motion of the subtalar joint.Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9).(Strong consensus). CONSENSUS STATEMENT TWO: When titrating the amount of correction of abduction deformity intraoperatively, the presence of adduction at the talonavicular joint on simulated weightbearing fluoroscopic imaging is an important sign of hypercorrection and higher risk for lateral column overload.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus). CONSENSUS STATEMENT THREE: The typical range for performing a lateral column lengthening is between 5 and 10 mm to achieve an adequate amount of talonavicular coverage.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus).

The relationship between measures of foot mobility and subtalar joint stiffness using vibration energy with color Doppler imaging-A clinical proof-of-concept validation study.

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, ΔTU), 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 ΔTU (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 ΔTU 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 ΔTUs, 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 ΔTU (p< .001), dorsum PROM (p = .017), and posterior PROM (p = .036). Post-hoc tests revealed significant: (1) ΔTU 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.

Acquired multi-segment foot kinematics in haemophilic children, adolescents and young adults with or without haemophilic ankle arthropathy.

INTRODUCTION AND AIM: The ankle joint remains vulnerable in children with haemophilia and is the primary joint affected. The purpose of this study was to dynamically characterize the segmental foot and ankle kinematics of male children, adolescents and young adults with or without ankle arthropathy. METHODS: The barefoot multi-segment foot kinematics of 70 ankles from 35 haemophilia subjects between 6 and 20 years old were captured with the Rizzoli Multi-Segment Foot Model. Joint damage of the tibiotalar and subtalar joints was scored using the IPSG-MRI score. The feet of patients with or without evidence of ankle arthropathy were compared with those of matched typically developing boys via a nonpaired comparison. The differences between the affected and nonaffected sides of patients with unilateral ankle arthropathy were assessed using a paired comparison. RESULTS: Subjects without arthropathy demonstrated a nonsignificant trend towards a higher frontal plane range of motion (RoM) at the midfoot upon loading response and a lower sagittal plane RoM at the midfoot during midstance. No differences were observed between the affected side group and their matched control group. The affected side of unilaterally affected subjects exhibited a nonsignificant tendency towards a higher frontal plane RoM at the ankle joint upon loading response and terminal stance compared to the healthy side. CONCLUSION: Most patients maintained physiological rocker function of the ankle and had no (mal)adaptive motion patterns in the more distal joints of the foot. Therefore, established structural lesions may remain subclinical with respect to moderate functional activities like walking.

Correction of excessive intraarticular varus deformities in total knee arthroplasty is associated with deteriorated postoperative ankle function.

PURPOSE: The aim of this study was to demonstrate, whether the degree of limb alignment correction in varus knee osteoarthritis correlated with an increase in ankle symptoms and to define a cut-off value concerning the degree of correction above which to expect ankle problems. METHODS: Ninety-nine consecutive patients with preoperative intraarticular varus knee deformities who underwent total knee arthroplasty were retrospectively analyzed. Patients were examined clinically (Knee Society Score, Forgotten Joint Score, Foot Function Index, Range of Motion of the knee and ankle joint, pain scales) as well as radiologically. The mean follow-up time was 57 months. RESULTS: The degree of operative limb alignment correction strongly correlated with the Foot Function Index (R = 0.91, p < 0.05). Given this, higher degrees of knee malalignment corrections were associated with worse postoperative outcomes in the knee and ankle joint-despite postoperative improved joint line orientations. Subsequently, a cut-off value for arthritic varus deformities (14.5°) could be calculated, above which the prevalence of ankle symptoms increased manifold [OR = 15.6 (3.2-77.2 95% CI p < 0.05)]. Furthermore, ROM restrictions in the subtalar joint were associated with a worse outcome in the ankle joint. CONCLUSIONS: When correcting excessive intraarticular varus knee osteoarthritis, surgeons have to be aware of possible postoperative ankle symptoms and should consider ankle deformities or decreased subtalar ROM before operative procedures. LEVEL OF EVIDENCE: III.

Functional and Radiological Outcomes After Tarsal Coalition Resections: A Minimum 5-Year Follow-Up.

Few studies have evaluated the long-term functional and radiological outcomes of tarsal coalition resections. This study aimed to report and compare the functional and radiological outcomes after talocalcaneal (TC) and calcaneonavicular (CN) coalition resections. Thirty-three patients between 12 and 35 years old with symptomatic tarsal coalitions participated, each undergoing tarsal coalition resections (24 TC and 9 CN). The range of motion, visual analog scale score, American Orthopedic Foot and Ankle Society hindfoot scale, Maryland foot score, tripod index, and modified Kellgren-Lawrence scale for subtalar osteoarthritis were used to evaluate the functional and radiological outcomes. The mean age at the time of surgery and mean follow-up in the TC group were 17.8 ± 5.6 years (range 13 to 35) and 6.2 ± 1.7 years (range 5 to 12), respectively, and 16.0 ± 4.4 years (range 12 to 23) and 7.7 ± 3.0 years (range, 5 to 12) in the CN group. There was no difference in the range of motion, outcome scores, tripod index score, and modified Kellgren-Lawrence scale score between patients in the 2 groups. A positive correlation was noted between the size of the TC coalition, coalition/joint surface ratio, and hindfoot valgus angle regarding outcome scores. However, there was no association between the modified Kellgren-Lawrence scale score and outcome scores. At the minimum 5-year follow-up, the functional and radiological outcomes were similar between TC and CN resections. Subtalar joint osteoarthritis developed in all patients with TC resections and most patients with CN resections, but patients did not have functional impairment.

Arthroereisis for Symptomatic Flexible Flatfoot Deformity in Young Children: Radiological Assessment and Short-Term Follow-Up.

The purpose of this study is to recognize those young patients with symptomatic flexible flatfoot deformity who need treatment and to provide radiological evidence that arthroereisis is capable of relocating the talus properly over the calcaneus. We included 28 feet in 14 children who underwent subtalar arthroereisis in association with percutaneous triple-hemisection Achilles tendon lengthening. Selected for arthroereisis were children with symptomatic flexible flatfoot deformity who complained of foot and leg pain, had decreased endurance in sports activities and long walks, who did not respond to conservative treatment modalities for at least 6 months, and in whom at radiological assessment on stance position with the medial arch support orthosis the talonavicular joint lateral subluxation still remained, with Meary's angle in anteroposterior (A/P) and lateral view remaining increased. The mean age at surgery was 10.71 ± 1.58 (range 8 to 14) years. The minimum follow-up duration was 19 months, with mean follow-up duration of 35.14 ± 9.82 (range 19 to 60) months. For estimation of the efficacy of the surgical procedure, the American Orthopaedic Foot and Ankle Society (AFOAS) rating scale was used preoperatively and postoperatively in all patients. The mean preoperative AFOAS ankle-hind foot rating score was 65.14 ± 7.16 (range 58 to 75) points. The mean postoperative AFOAS score was 88.851 ± 5.61 (range 83 to 97) points and the 2-tailed p value <.0001. After arthroereisis surgical treatment, all AOFAS scores and all foot angles improved significantly, except the calcaneal inclination angle which improved slightly.

In vivo kinematics of functional ankle instability patients during the stance phase of walking.

BACKGROUND: Previous studies showed functional ankle instability (FAI) patients have morphological ligamentous abnormality, despite having no apparent joint laxity. RESEARCH QUESTION: Whether tibiotalar and subtalar joints hypermobility exists in FAI patients during stance phase of walking, remains controversial. METHODS: Ten unilateral FAI patients, ten unilateral lateral ankle sprain (LAS) copers and ten healthy controls were included. A dual fluoroscopy imaging system was utilized to capture the fluoroscopic images of tibiotalar and subtalar joint during the stance phase of walking. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint excursions about six degrees of freedom were compared among the three groups. The correlations between range of motion and Cumberland Ankle Instability Tool (CAIT) scores were assessed utilizing the Spearman's correlation coefficient (r). RESULTS: During the stance phase, the FAI patients and LAS copers showed larger tibiotalar anterior/posterior translation than the healthy controls (FAI patients, p = .013; LAS copers, p = .002). The FAI patients also showed significantly larger lateral/medial translation (p = .035) and inversion/eversion rotation (p = .003) of subtalar joints than healthy controls. By contrast, the subtalar joints of the LAS copers were not different from those of the healthy controls in the lateral/medial translation (p = .459) and inversion/eversion rotation (p = .091). CAIT scores were negatively correlated with range of motion. SIGNIFICANCE: During the stance phase of walking, FAI patients showed significantly larger hypermobility of subtalar joints than healthy controls, contrary to the LAS copers. These findings justify the utilization of dual fluoroscopy imaging system to detect joint hypermobility in FAI patients. Treatment for FAI patients may require stabilization of the subtalar joint.

The increase of joint contact forces in foot joints with simulated subtalar fusion in healthy subjects.

BACKGROUND: Subtalar fusion usually leads to a satisfactory clinical outcome by eliminating the motion of the subtalar joint but can cause an aggravation of osteoarthritis after the subtalar fusion. Previous studies have investigated the effect of subtalar fusion in static testing using cadaver limbs, but there was no evidence of an aggravation of osteoarthritis. RESEARCH QUESTION: The objective was to investigate the differences in foot joint kinematics and kinetics during a standing pose and walking with and without subtalar fusion, using a musculoskeletal simulation. METHODS: Full-body joint kinematics, ground reaction force, and foot pressure of the healthy subjects were recorded during walking using an optical motion capture system. The models with and without subtalar fusion were constructed using the AnyBody Modeling System (AnyBody Technology, Aalborg, Denmark). The range of motion and contact forces in the individual foot joints with and without simulated subtalar fusion in healthy subjects were estimated using computational simulation and compared using the Wilcoxon signed-rank test. The change of motion in the Chopart's joint was observed. RESULTS: Normalized to the subject's body weight (BW), the average maximum contact forces in the tibiotalar and Lisfranc joints during walking were significantly increased by 2.6 and 0.9 BW with the simulated subtalar joint fusion, respectively. The simulated subtalar joint fusion increased joint contact forces significantly during walking, which can increase the risks of secondary arthritis in the adjacent joints. SIGNIFICANCE: The subtalar joint fusion increased the joint contact forces in adjacent joints during walking implying that the fusion can increase the risk of secondary injuries in adjacent joints in the foot.

Secondary Subtalar Joint Osteoarthritis Following Total Ankle Replacement.

BACKGROUND: An advantage of total ankle replacement (TAR) compared to ankle fusion is that by maintaining motion, the occurrence of hypermobility of adjacent joints may be prevented. This could affect the development of symptomatic subtalar joint osteoarthritis (OA). The aim of the study was to determine the incidence of subtalar joint fusion and the progression of subtalar joint OA following TAR. METHODS: Secondary subtalar joint fusion rate was determined from a cohort of 941 patients receiving primary TAR between 2000 and 2016. The indication for fusion, the time interval from primary TAR to fusion, and the union rate were evaluated. To assess the progression of subtalar joint OA, degenerative changes of the subtalar joint were classified in 671 patients using the Kellgren-Lawrence score (KLS) prior to TAR and at latest follow-up. RESULTS: In 4% (37) of the patients, a secondary subtalar joint fusion was necessary. The indication for fusion was symptomatic OA in 51% (19), hindfoot instability in 27% (10), osteonecrosis of the talus in 19% (7), and cystic changes of the talus in 3% (1) of the patients. Time from primary TAR to subtalar joint fusion due to progressive OA was 5.0 (range, 0.3-10) years and for other reasons 1.6 (range, 0.2-11.6) years (P = .3). In 68% (456) of the patients, no progression of subtalar joint OA was observed. CONCLUSION: The incidence of secondary subtalar joint fusion was low. The most common reason for subtalar joint fusion following TAR was symptomatic OA. LEVEL OF EVIDENCE: Level IV, case series.

Effect of a Semirigid Ankle Brace on the In Vivo Kinematics of Patients with Functional Ankle Instability during the Stance Phase of Walking.

An ankle brace is commonly used by patients after they suffer from initial ankle sprains, reducing the incidents of recurrent sprain or limiting laxity in joints with functional ankle instability (FAI). However, whether the application of a semirigid ankle brace can improve the abnormal ankle gait kinematics of patients with FAI remains unknown. This study aimed to determine the effect of a semirigid ankle brace on the gait kinematics of ankle joints through 3D-2D fluoroscopy image registration. A total of 8 subjects with FAI (3 males and 5 females, 10 feet) as FAI group and 10 subjects without FAI (6 males and 4 females, 10 feet) as control group were enrolled in this study. Three-dimensional bone models created from computed tomography images were matched to fluoroscopic images to compute the 6 degrees of freedom (DOF) talocrural, subtalar, and ankle joints complex kinematics for control and FAI group with or without brace during the stance phase of walking. FAI patients had significantly less ROMs in inversion/eversion rotation of the talocrural and subtalar joint after wearing semirigid ankle brace. Laxity was observed in most of the displacements of the talocrural and subtalar joints in FAI group. The brace partly altered the ankle joints movement in opposite directions, especially joint rotation, and restricted the talocrural and subtalar joints in the dorsiflexion position during the touch down phase of walking.

Technique Article: Tarsal Coalition Resection Using Kirschner Wires Across the Subtalar Joint in a Two-Incision Approach.

Subtalar coalitions are a significant cause of morbidity, especially in the pediatric population. Arthrodesis was considered the standard of care, with coalitions involving >50% of the joint until the mid-1990s. Today, some are recommending resection of the coalition first and to save hindfoot arthrodesis as a salvage procedure. As a result, resection of talocalcaneal coalitions is becoming more common, and optimizing the surgical technique is a necessity in the field of orthopedics. We present a technique to optimize surgical resection of talocalcaneal coalitions by using Kirschner wires inserted from the lateral side, which allows us to demarcate the coalition. This gives us a greater ability to perform a more complete resection and also helps prevent iatrogenic trauma to the articulating surface.

Bilateral Triple Talocalcaneal, Calcaneonavicular, and Talonavicular Tarsal Coalition: A Case Report.

We report a rare case of a female, aged 42 years, with symptomatic bilateral triple tarsal coalition, that is, talocalcaneal, calcaneonavicular, and talonavicular tarsal coalition. The patient was treated conservatively by adjusting her activities. At the 12-month follow-up, the patient was asymptomatic. Bilateral triple tarsal coalition is a rare disorder, especially in nonsyndromic patients. The purpose of this case report was to highlight this rare type of multiple bilateral tarsal coalitions and to discuss the relevant existing literature.

Adverse Events and Their Risk Factors Following Intra-articular Corticosteroid Injections of the Ankle or Subtalar Joint.

BACKGROUND: Little data exists regarding the incidence of adverse events and their associated risk factors following intra-articular corticosteroid injection of the ankle and subtalar joint. The aim of this study was to determine the complication rate associated with such injections and to identify any predictive risk factors. METHODS: Adult patients who had received an intra-articular ankle or subtalar joint injection between January 2000 and April 2016 at one of 3 regional hospitals (2 level 1 trauma centers and 1 community hospital) were included. Patients with prior intra-articular injection of corticosteroid into the ankle or subtalar joint were excluded. Explanatory variables were sex, age, race, body mass index, diabetes status, tobacco use, presence of fluoroscopic guidance, location of intra-articular injection, and administering physician's years of experience. RESULTS: Of the 1708 patients included in the final cohort, 99 patients (5.8%) had a total of 104 adverse events within 90 days postinjection. The most prevalent types of adverse events were postinjection flare in 78 patients (4.6% of total cohort, 75% of adverse events) followed by skin reaction in 10 patients (0.6% of total cohort, 9% of adverse events). No infections were noted. Multivariable logistic regression analysis found that intra-articular injection in the subtalar ( P = .004) was independently associated with development of an adverse event. Fluoroscopic guidance was not found to be protective of an adverse event compared to nonguided injections ( P = .476). CONCLUSION: The adverse event rate following intra-articular ankle or subtalar joint corticosteroid injection was 5.8%, with postinjection flare being the most common complication. Infections following injection were not reported. Injection into the subtalar joint was independently associated with the development of an adverse event after intra-articular corticosteroid injection, and this was not mitigated by the use of fluoroscopic guidance. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Analysis of the stress distribution of the subtalar joint and fusion efficacy after double-screw insertion.

BACKGROUND: Screw fixation is a typical technique for the isolated subtalar joint. However, no consensus has been reached on how to select the most suitable insertion position and direction. This study aims to find the ideal screw insertion and then explore its influence on the clinical efficacy of subtalar fusion by analyzing the effects of different cannulated screw insertions on the stress distribution, anti-rotary strength, and anti-inversion/eversion strength of the subtalar joint. METHODS: In this study, we investigated three cannulated screw insertions for subtalar fusion: screw insertion with the most uniform stress distribution (group A), lateral-medial parallel screw insertion (group B), and traditional longitudinally parallel screw insertion (group C). The effects of these three insertions on the loading stress of the subtalar joint (including stress distribution, anti-inversion/eversion strength, and anti-rotary strength) were comparatively analyzed with the three-dimensional finite element method to screen the ideal screw insertion. Moreover, a prospective study was conducted to analyze the influence of the ideal screw insertion on subtalar fusion, including the fusion rate, fusion time, and clinical efficacy (VAS score, AOFAS score, and complications). RESULTS: Group B was worse than group A with respect to the stress distribution uniformity, but slightly better than group C, and better than both groups A and C in terms of the anti-rotary strength and anti-inversion/eversion strength. The screw insertion based on the most uniform stress distribution is not feasible in surgery. Therefore, the lateral-medial antiparallel screw insertion is the ideal insertion. From January 2012 to June 2016, 48 cases were treated by subtalar fusion with the ideal screw insertion, and then followed up for 30.6 months (12-48 months). The fusion was proved in all 48 cases with a fusion rate of 100% by X-ray or CT scan. The mean time of fusion was 12.8 weeks (12-16 weeks). The VAS score decreased from 6.00 before operation to 1.03 on the last visit (P < 0.05), and the AOFAS score increased from 57.0 to 85.6 (P < 0.05), with a good and excellent rate of 95.8%. CONCLUSIONS: The lateral-medial parallel screw insertion not only demonstrates a good stress distribution profile of the subtalar joint but also has advantages such as easy localization and operation during surgery, as well as a high fusion rate and few complications after surgery. Therefore, it is a safe, accurate, and effective fixation mode that is worthy of being popularized clinically.