A Unique Approach to Irreparable Radial Head Fracture Using an Osteochondral Plug: A Case Report.

CASE: An 18-year-old male patient sustained a traumatic injury that resulted in the loss of approximately 50% of the radial head. Subsequently, reconstruction was performed by transplanting an osteochondral plug harvested from the lateral femoral condyle. At the 1-year postoperative follow-up, the patient was pain-free and had a good range of motion. CONCLUSION: Using a novel technique, an irreparable radial head fracture was reconstructed using an osteochondral plug from the lateral femoral condyle. Reconstruction with osteochondral plugs may be a treatment option for partial loss of the radial head.

Skeletal muscle injury treatment using the Silk Elastin® injection in a rat model.

Background: Skeletal muscle injury (SMI) is often treated conservatively, although it can lead to scar tissue formation, which impedes muscle function and increases muscle re-injury risk. However, effective interventions for SMIs are yet to be established. Hypothesis: The administration of Silk Elastin® (SE), a novel artificial protein, to the SMI site can suppress scar formation and promote tissue repair. Study design: A controlled laboratory study. Methods: In vitro: Fibroblast migration ability was assessed using a scratch assay. SE solution was added to the culture medium, and the fibroblast migration ability was compared across different concentrations. In vivo: An SMI model was established with Sprague-Dawley rats, which were assigned to three groups based on the material injected to the SMI site: SE gel (SE group; n = 8), atelocollagen gel (Atelo group; n = 8), and phosphate buffer saline (PBS group; n = 8). Histological evaluations were performed at weeks 1 and 4 following the SMI induction. In the 1-week model, we detected the expression of transforming growth factor (TGF)-ß1 in the stroma using immunohistological evaluation and real-time polymerase chain reaction analysis. In the 4-week model, we measured tibialis anterior muscle strength upon peroneal nerve stimulation as a functional assessment. Results: In vitro: The fibroblast migration ability was suppressed by SE added at a concentration of 104 µg/mL in the culture medium. In vivo: In the 1-week model, the SE group exhibited significantly lower TGFß -1 expression than the PBS group. In the 4-week model, the SE group had a significantly larger regenerated muscle fiber diameter and smaller scar formation area ratio than the other two groups. Moreover, the SE group was superior to the other two groups in terms of regenerative muscle strength. Conclusion: Injection of SE gel to the SMI site may inhibit tissue scarring by reducing excessive fibroblast migration, thereby enhancing tissue repair. Clinical relevance: The findings of this study may contribute to the development of an early intervention method for SMIs.

Development of a novel approach for restoration of the meniscus using silk-elastin in a rabbit meniscus injury model.

BACKGROUND: Limited healing potential of the meniscus remains a burden for the successful repair of meniscus injuries in the orthopaedic fields. Silk-elastin (SE) is a novel recombinant protein with favorable properties for wound healing. This proof-of-concept study aimed to investigate the therapeutic effect of silk-elastin in a rabbit meniscal defect model. METHODS: A migration assay using rabbit meniscus and synovial cells with various concentrations of SE in a culture medium was conducted to investigate the mechanism of meniscal healing by SE. Additionally, cylindrical defects with a 1.5 mm diameter were created at the anterior horn of the medial meniscus of rabbits. The animals were divided into three groups: 1) the Blank group; defect only, 2) the Col I group; implantation of type I atelocollagen sponge, and 3) the SE group; implantation of SE (150 mg/ml) sponge. Whole medial menisci were harvested at 4, 8, 12, and 24 weeks after surgery. Histological analyses including immunohistochemical staining were performed to assess meniscal healing. RESULTS: In vitro study, Migration assay demonstrated a significantly higher number of migrated cells only in synovial cells. Especially, the SE concentration of 10 µg/mL demonstrated the highest number of migrated cells compared with other concentrations. In vivo study, the SE group exhibited significantly higher Ishida scores than other groups at all time points. Furthermore, the SE group showed higher synovial coverage scores than the Col I group at 4 and 8 weeks. Immunohistochemical staining demonstrated higher type II collagen staining in the SE group compared to other groups at 12 weeks. Implanted SE was efficiently replaced by safranin-O staining positive tissue within 8 weeks. CONCLUSIONS: SE could effectively repair a meniscal defect by inducing coverage of synovial cells. SE has the potential to be a useful material for meniscal repair.

Articular cartilage damage in the patellofemoral compartment at ACL reconstruction predicts poor postoperative subjective outcomes in patients age 40 and older.

The purpose of this study was to investigate factors that influence clinical outcomes after ACL reconstruction in patients age 40 and older. We studied 264 patients aged 40 or older and 154 patients aged 20 or younger who underwent ACL reconstruction at several surgical centers. Logistic regression analysis was conducted to identify factors that influenced the KOOS scores at 1 year post ACL reconstruction. In the older patient group, cartilage damage in the patellofemoral compartment at surgery was a significant risk factor for poor postoperative KOOS subscores (pain, ADL, sports, and QOL). Articular cartilage damage in the lateral compartment also significantly influenced one of the postoperative KOOS subscores (symptoms). In the younger patient group, articular cartilage damage in any compartments did not influenced the postoperative KOOS subscores; only two preoperative KOOS subscores (symptoms and QOL) significantly influenced their postoperative KOOS subscores. We concluded that the articular cartilage damage in the patellofemoral compartment at ACL reconstruction predicts poor KOOS subscores at one year follow-up in patients age 40 or older.

Effects of Preoperative Abnormality of Posterior Tibial Tendon on the Surgical Outcomes of Medial Osteochondral Lesion of the Talus.

BACKGROUND: Although surgical treatment for osteochondral lesion of the talus (OLT) can obtain good clinical outcomes, the rate of return to sports is variable. It is reported that medial OLT unrelated to trauma has abnormal structures in the medial aspect, which may induce the medial OLT due to the medial instability. The posterior tibial tendon (PTT) plays an important role in the stabilization of the foot, and high mechanical stress may be added to the PTT to compensate for medial instability in medial OLT. We investigated whether abnormal PTT findings on preoperative magnetic resonance imaging (MRI) in patients with OLT affect clinical outcomes after surgery.  Methods: Eighty-one ankles in 74 patients who were treated surgically for OLT were included in this study (41 men and 33 women; mean age, 26.0 years). Abnormalities of the PTT were evaluated using preoperative MRI. The Japanese Society for Surgery of the Foot (JSSF) scale, arch height, and ankle activity score (AAS) on standing plain radiogram were compared between patients with and those without preoperative PTT abnormalities. RESULTS: Twenty-five ankles (30.9%) had PTT abnormalities on preoperative MRI. All patients with preoperative PTT abnormalities were medial OLT. There were no significant differences in the preoperative JSSF scale in the procedures for OLT. The postoperative JSSF scale and arch height were significantly lower in patients with preoperative PTT abnormalities than those without them. AAS in patients with preoperative abnormalities significantly decreased at the final follow-up.  Conclusion: PTT abnormalities on preoperative MRI may affect clinical outcomes even in preoperative asymptomatic patients in the medial OLT unrelated to trauma.

Temporal validation of a clinical prediction rule for distinguishing locomotive syndromes in community-dwelling older adults: A cross-sectional study from the DETECt-L study.

Objectives: Clinical prediction rules are used to discriminate patients with locomotive syndrome and may enable early detection. This study aimed to validate the clinical predictive rules for locomotive syndrome in community-dwelling older adults. Methods: We assessed the clinical prediction rules for locomotive syndrome in a cross-sectional setting. The age, sex, and body mass index of participants were recorded. Five physical function tests-grip strength, single-leg standing time, timed up-and-go test, and preferred and maximum walking speeds-were measured as predictive factors. Three previously developed clinical prediction models for determining the severity of locomotive syndrome were assessed using a decision tree analysis. To assess validity, the sensitivity, specificity, likelihood ratio, and post-test probability of the clinical prediction rules were calculated using receiver operating characteristic curve analysis for each model. Results: Overall, 280 older adults were included (240 women; mean age, 74.8 ± 5.2 years), and 232 (82.9%), 68 (24.3%), and 28 (10.0%) participants had locomotive syndrome stages ≥ 1, ≥ 2, and = 3, respectively. The areas under the receiver operating characteristics curves were 0.701, 0.709, and 0.603, in models 1, 2, and 3, respectively. The accuracies of models 1 and 2 were moderate. Conclusions: These findings indicate that the models are reliable for community-dwelling older adults.

Development of an Original Three-Dimensional Computed Tomography Scan Method and Imaging Process for Surgical Support of the Anterior Cruciate Ligament.

Three-dimensional computed tomography (3D CT) scan images are useful as they can provide information essential for surgical support, particularly in orthopedic surgery. In the case of anterior cruciate ligament (ACL) reconstruction, a 3D CT scan is important in preoperative simulation. Furthermore, it is associated with a reduced risk of revision surgery because the angle of the foramen magnum changes with the femoral muscle mass. However, the CT scan system geometry has several limitations. For example, the patient's posture is limited during the procedure. Herein, we report an original CT scan method and 3D imaging process for surgical support of the ACL.

Variations in knee cartilage thickness: Fully automatic three-dimensional analysis of MRIs from five manufacturers.

BACKGROUND: Measurements of knee cartilage thickness derived from MR images are attractive biomarkers for osteoarthritis research. Although some cross-sectional multivendor studies exist, none have employed fully automatic three-dimensional MRI analysis. Our objective was to evaluate the variations in knee cartilage thickness measurements obtained using automated methods and MRI instruments from five different vendors. METHODS: The subjects were 10 healthy volunteers aged 22-60 years. MRI models with 3 Tesla strength from five different companies were used. Cartilage thickness was quantified fully automatically for seven regions. We hypothesized that "the MRI model influences cartilage thickness measurements." Inter-measurement error, defined as the absolute difference between the targeted and median thicknesses determined by the five MRI models, was analyzed using histograms. The factors generating the largest inter-measurement error were also examined. RESULTS: No exceptional trends attributable to a specific instrument model were observed, and the p-value from the Kruskal-Wallis test exceeded 0.05 in all seven regions. Therefore, the study hypothesis was rejected. Of the 350 measurements, the inter-measurement error was ≤0.05 mm in 53 %, ≤0.10 mm in 75 %, and ≤0.20 mm in 95 %. Analysis of the medial tibial cartilage, which had the largest inter-measurement error, revealed mis-extraction of synovial fluid as cartilage. CONCLUSIONS: The choice of MRI model did not influence cartilage thickness measurements. Overall, 95 % of the inter-measurement errors were within 0.20 mm. The greatest error resulted from mis-extracting synovial fluid as cartilage.

Differentiation of the Intradural Extramedullary Spinal Tumors, Schwannomas, and Meningiomas Utilizing the Contrast Ratio as a Quantitative Magnetic Resonance Imaging Method.

BACKGROUND: Schwannomas and meningiomas are the most common intradural extramedullary spinal tumors; however, differentiating between them using magnetic resonance imaging (MRI) is a frequent challenge. In this study, we aimed to investigate the use of the contrast ratio (CR) as a quantitative MRI method in the differentiation of schwannomas and meningiomas. METHODS: We analyzed the data of patients with intradural extramedullary spinal tumors who underwent surgery and were diagnosed with either schwannomas or meningiomas by histopathological analysis. Regions of interest were set for the entire spinal tumor on T2-weighted sagittal MRI. To obtain the CR values of spinal tumors (CRtumor), we used the signal intensity (SI) values of the tumor (SItumor) and spinal cord (SIcord) according to the following formula: [CRtumor = (SItumor-SIcord)/(SItumor+SIcord)]. RESULTS: The study included 50 patients (23 males and 27 females) with a mean age of 61.5 years old (11-85 years old). Histopathological analysis revealed that 33 and 17 patients were diagnosed with schwannomas and meningiomas, respectively. The mean CR values of the schwannomas and meningiomas were 0.3040 ± 0.1386 and 0.0173 ± 0.1929, respectively. The CR value of the schwannomas was statistically significantly higher than that of meningiomas (P < 0.01). The cutoff CR value obtained from the receiver operating characteristic curve was 0.143, with a specificity and sensitivity of 90.9% and 88.2%, respectively. Furthermore, the value for the area under the receiver operating characteristic curve was 0.925 (95% confidence interval: 0.852-0.998). CONCLUSIONS: The evaluation of CRs by using MRI to distinguish between schwannomas and meningiomas is a beneficial quantitative tool.

Increased Posterior Condylar Offset Decreases the Extension Gap in Cases With Flexion Contracture in Modified Gap Technique Total Knee Arthroplasty.

Purpose There have been no reports comparing the change in medial and lateral posterior condylar offset (PCO) and the extension gaps. The purpose of this study was to elucidate the relationship between the change in medial and lateral PCO and the extension gap in total knee arthroplasty (TKA). The hypothesis is that an increase in both medial and lateral PCO can be a factor for a decrease in the extension gap, especially in cases of flexion contracture. Methods This retrospective study included 63 patients with medial osteoarthritis who underwent mobile-bearing PS-TKA using the modified gap techniques. Patients consisted of seven men (seven knees) and 53 women (56 knees), with the mean age of 76 (range, 58-88) years. The patients with valgus knee and cruciate retaining TKA were excluded. The medial ΔPCO (ΔPCO defined as the amount of change of the PCO before the resection of the posterior condyle and after the implant setting), lateral ΔPCO, the rotation angle of the posterior condyle osteotomy, and the gap differences were evaluated. The data were compared among three groups（Group A: ΔPCO increase on both sides, Group B: ΔPCO increase on only one side, Group C: ΔPCO decrease on both sides. The gap differences were compared between the cases with flexion contracture of ≥ 15° and the cases with flexion contracture of < 15°. The correlations between the gap differences and flexion contracture were evaluated in each group. Results There was no gap difference evident in any group (P≥0.05). The gap difference in Groups A (P=0.0067) and group C (P=0.0484) was significantly larger in cases with flexion contracture of ≥ 15° compared to those with flexion contracture of < 15°. Conclusions There was no correlation between the change in PCO and the extension gap. However, there was an inverse correlation between the flexion contracture and extension gap in cases with increased medial and lateral PCO.

Osteophyte Cartilage as a Potential Source for Minced Cartilage Implantation: A Novel Approach for Articular Cartilage Repair in Osteoarthritis.

Osteoarthritis (OA) is a common joint disorder characterized by cartilage degeneration, often leading to pain and functional impairment. Minced cartilage implantation (MCI) has emerged as a promising one-step alternative for large cartilage defects. However, the source of chondrocytes for MCI remains a challenge, particularly in advanced OA, as normal cartilage is scarce. We performed in vitro studies to evaluate the feasibility of MCI using osteophyte cartilage, which is present in patients with advanced OA. Osteophyte and articular cartilage samples were obtained from 22 patients who underwent total knee arthroplasty. Chondrocyte migration and proliferation were assessed using cartilage fragment/atelocollagen composites to compare the characteristics and regenerative potential of osteophytes and articular cartilage. Histological analysis revealed differences in cartilage composition between osteophytes and articular cartilage, with higher expression of type X collagen and increased chondrocyte proliferation in the osteophyte cartilage. Gene expression analysis identified distinct gene expression profiles between osteophytes and articular cartilage; the expression levels of COL2A1, ACAN, and SOX9 were not significantly different. Chondrocytes derived from osteophyte cartilage exhibit enhanced proliferation, and glycosaminoglycan production is increased in both osteophytes and articular cartilage. Osteophyte cartilage may serve as a viable alternative source of MCI for treating large cartilage defects in OA.

Nonunion of Isolated Medial Cuneiform Fracture Fixed With a Compression Screw and Compression Staple: A Case Report.

Isolated cuneiform fractures are rare and account for only 1.7% of all midfoot fractures. Medial cuneiform fractures can be treated conservatively or surgically, with good clinical outcomes. However, nonunion is a rare complication of medial cuneiform fractures, and only a few cases have been reported in the literature. We report a case of a medial cuneiform fracture requiring surgical treatment that had a good clinical outcome. A 15-year-old boy presented to an orthopedic clinic with a complaint of pain in his right foot. The patient had landed on the foot during a handball game and was treated conservatively for several months. However, his symptoms persisted, and he was referred to our clinic for further evaluation, where he was diagnosed with medial cuneiform nonunion of the right foot. Open reduction and internal fixation surgery using a compression screw and staple and autologous bone grafting were performed. Postoperatively, bone union was observed, and the patient returned to full competition with no complaints of pain during exercise. The Self-Administered Foot Evaluation Questionnaire (SAFE-Q) score at 21 months after surgery was 100.0 for the following subscales: Pain & Pain-Related; Physical Functioning & Daily Living; Social Functioning; Shoe-Related; General Health & Well-Being; and Sport (handball). We encountered a case of an isolated medial cuneiform fracture that required surgical treatment. During the surgical treatment, fixation with a combination of compression staples and screws may be considered simple and useful for achieving strong fixation because the medial cuneiform fracture has a small bone fragment.

Evaluation of articular cartilage degeneration in patients with osteonecrosis of the femoral head using T2 mapping magnetic resonance imaging.

OBJECTIVES: To evaluate and characterise articular cartilage degeneration in patients with osteonecrosis of the femoral head (ONFH) using T2 mapping magnetic resonance imaging (MRI). METHODS: We reviewed 35 patients with ONFH (20 males and 15 females, mean age 45.7±12.9 years) without obvious cartilage abnormalities on plain MRI (ONFH group) and 25 healthy volunteers (9 males and 16 females, mean age 42.9±5.8 years) (control group). All patients underwent T2 mapping MRI after ONFH onset. The region of interest was defined as the weight-bearing portion of the articular cartilage in the femoral head and acetabulum in the coronal view. RESULTS: The T2 values of the articular cartilage of the acetabulum and femoral head, including necrotic and normal regions, were significantly higher in the ONFH group than those in the control group. These T2 values of the acetabulum and femoral head in stages 3A and 2 were significantly higher in the ONFH group than those in the control group. CONCLUSIONS: The articular cartilage of the acetabulum and femoral head can deteriorate after the onset of ONFH, which may affect the natural history of ONFH and ONFH treatment. Our findings suggest the need for early intervention in joint preservation surgery.

Three-dimensional motion analysis of pre- and postoperative thumb movement in trapeziometacarpal joint osteoarthritis-Comparison of arthrodesis and trapeziectomy with suspensionplasty.

Trapeziometacarpal osteoarthritis (TMC-OA) reduces the range of motion (ROM) of the thumb. However, the kinematic change achieved through surgical treatment remains unclear. Therefore, to quantify the kinematic change following TMC-OA surgery, we performed a three-dimensional motion analysis of the thumb using an optical motion capture system preoperatively and 1 year postoperatively in 23 patients with TMC-OA scheduled for arthrodesis (AD) or trapeziectomy with suspensionplasty (TS). Eighteen hands of nine healthy volunteers were also included as controls. Both procedures improved postoperative pain and Disability of the Arm, Shoulder and Hand scores, and AD increased pinch strength. The ROM of the base of the thumb was preserved in AD, which was thought to be due to the appearance of compensatory movements of adjacent joints even if the ROM of the TMC joint was lost. TS did not improve ROM. Quantifying thumb kinematic changes following TMC-OA surgery can improve our understanding of TMC-OA treatment and help select surgical procedures and postoperative assessment.

Temporary meniscus extrusion is caused by cumulative stress from uphill and downhill tasks in healthy volunteers.

Purpose: Excessive mechanical stress accumulates and causes knee injury. Meniscal extrusion is a key factor in detecting the reaction to cumulative mechanical stress. The accumulation of stress strongly depends on environmental conditions such as flat ground or uphill/downhill, and accumulates in knee compartments; only a few studies have reported the effects of different environments on lateral and medial meniscus extrusion. This study aimed to investigate the effects of cumulative uphill/downhill stress on the meniscal extrusion in each compartment. Methods: A total of 30 healthy volunteers with 30 affected knees were involved in this cohort study (mean age, 22.0 ± 1.1 years; men, n = 14). The participants were divided into flat-walking, uphill/downhill-walking, and uphill/downhill-jogging groups and their numbers of steps taken were recorded during the effort. Moreover, medial and lateral meniscal extrusions during walking were evaluated using ultrasound three times, before and after efforts (T1) and (T2), and one day after efforts (T3), respectively. Results: In the flat-walking group, no significant differences were observed between the follow-up periods. Conversely, in the uphill/downhill-walking and jogging groups, the medial meniscus extrusion at T2 was significantly higher than that at T1. Conversely, the medial meniscus extrusion at T3 was significantly lower than that at T2. By contrast, the lateral meniscus did not show any difference between the follow-up periods in any group. Conclusion: Temporary extrusion of the meniscus occurred after uphill/downhill tasks in healthy volunteers, and its reaction was observed only in the medial meniscus.

Effect of lateral wedge length on knee adduction moment reduction mechanics during gait.

Lateral wedge insole (LWI) wear is a well-known conservative treatment for patients with knee osteoarthritis and is expected to decrease knee joint loading. Although the effect of LWI length on knee adduction moment (KAM) has been investigated, the biomechanical mechanism has not been fully investigated. Twelve healthy young subjects walked in the laboratory with and without 2 different lengths of LWIs. Three-dimensional motion analysis was performed to calculate the first and second peaks and impulses of the KAM during the stance phase. In addition, the knee-ground reaction force lever arm (KLA) and center of pressure (COP), ankle eversion moment, and ankle eversion angle were calculated. The first peak of KAM was lower, COP was displaced outward, and KLA was shorter with both LWIs attached. On the other hand, the second peak of KAM was lower with longer LWIs, COP was displaced outward, and KLA was shorter. The KAM impulse was significantly smaller in the condition with longer LWI than in the other conditions with smaller ankle eversion motion; longer LWI induced COP to the lateral side through the stance phase and kept KLA short, thus reducing the KAM impulse.

Dependence on visual information in patients with ACL injury for multi-joint coordination during single-leg squats: a case control study.

BACKGROUND: The influence of vision on multi-joint control during dynamic tasks in anterior cruciate ligament (ACL) deficient patients is unknown. Thus, the purpose of this study was to establish a new method for quantifying neuromuscular control by focusing on the variability of multi-joint movement under conditions with different visual information and to determine the cutoff for potential biomarkers of injury risk in ACL deficient individuals. METHODS: Twenty-three ACL deficient patients and 23 healthy subjects participated in this study. They performed single-leg squats under two different conditions: open eyes (OE) and closed eyes (CE). Multi-joint coordination was calculated with the coupling angle of hip flexion, hip abduction and knee flexion. Non-linear analyses were performed on the coupling angle. Dependence on vision was compared between groups by calculating the CE/OE index for each variable. Cutoff values were calculated using ROC curves with ACL injury as the dependent variable and significant variables as independent variables. RESULTS: The sample entropy of the coupling angle was increased in all groups under the CE condition (P < 0.001). The CE/OE index of coupling angle variability during the descending phase was higher in ACL deficient limbs than in the limbs of healthy participants (P = 0.036). The CE/OE index of sample entropy was higher in the uninjured limbs of ACL deficient patients than in the limbs of healthy participants (P = 0.027). The cutoff value of the CE/OE index of sample entropy was calculated to be 1.477 (Sensitivity 0.957, specificity 0.478). CONCLUSION: ACL deficient patients depended on vision to control multiple joint movements not only on the ACL deficient side but also on the uninjured side during single leg squat task. These findings underscore the importance of considering visual dependence in the assessment and rehabilitation of neuromuscular control in ACL deficient individuals.

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. LEVEL OF EVIDENCE: Level III, retrospective cohort study.