A mouse model of ankle-subtalar joint complex instability induced post-traumatic osteoarthritis

Corticospinal tract alterations after ankle sprain in adolescence: Insights from the mouse model

Purpose

Lateral ankle sprains (LAS) are associated with corticospinal pathway deficits. Existing evidence is primarily based on cross-sectional investigations and noncausal speculations. This study aims to determine whether maladaptive corticospinal pathway alterations occur pre- and postligament transection in LAS mouse models. Additionally, this study explores whether the alterations are more pronounced in adolescent mice than adults.

Methods

Twenty-four 8-week-old adolescent and twenty-four 24-week-old adult mice were randomly assigned to lateral ankle ligament transection or sham surgery. Diffusion-weighted imaging of the corticospinal pathway was performed presurgery and 8 weeks postsurgery. Fractional anisotropy (FA) values, reflecting fiber integrity within the corticospinal subregions of the medulla, pons, midbrain, and cerebrum, were extracted.

Results

Overall, 41 mice completed repeated image acquisition. Before surgery, no significant group effects on FA within the four corticospinal subregions were detected in either adolescent or adult mice. Two months after surgery, the adolescent cohort displayed a significant reduction in FA in the medulla subregion following ankle ligament transection (β-baseline-adjusted ​= ​-0.083, 95% CI , -0.145 to -0.021, p-corrected ​= ​0.048). Conversely, no significant effects of ankle ligament transection on corticospinal FA were observed in the adult cohort.

Conclusion

The maladaptive alterations in the corticospinal tract could be observed in the adolescent LAS mouse model, characterized by reduced fiber integrity in the medulla subregion. While these results are derived from an animal model, they provide a foundation for future investigations into the mechanisms underlying neurological deficits following musculoskeletal injuries.

Risk factors associated with subtalar fusion within 5 years following calcaneal ORIF

BACKGROUND

Although most calcaneal fractures are managed with open reduction internal fixation (ORIF), they can ultimately lead to subtalar arthritis and pain requiring subtalar fusion when conservative treatments prove ineffective. Understanding the risk factors associated with subtalar fusion (STF) after calcaneal ORIF is crucial for optimizing patient outcomes and treatment strategies. This study aimed to comprehensively evaluate these risk factors and their association with the incidence of STF, including patient demographics, medical comorbidities, same day and 90-day reimbursement data.

METHODS

A retrospective analysis was performed using the PearlDiver Mariner 157 national claims database from January 1st, 2010 to October 31st, 2021. Patients who underwent calcaneal ORIF, identified using Current Procedural Terminology (CPT) and ICD Procedure Codes were queried for 5-year rates of STF and reimbursement data. Patient demographics and comorbidities were recorded, and multivariate logistic regression was employed to determine the association of risk factors with STF.

RESULTS

Patients with STF had a higher proportion of alcohol abuse (21.3 % vs. 16.2 %), depression (58.1 % vs. 43.1 %), drug abuse (29.1 % vs. 19.7 %), obesity (40.3 % vs. 28 %) and tobacco use (62.2 % vs. 50.3 %), all exhibiting a p-value of less than 0.001. Those with depression (OR: 1.54; 99 % CI:1.29-1.84; P < 0.001) and obesity (OR:1.58; 99 % CI: 1.32-1.88; P < 0.001) as comorbidities had a higher odds ratio of association with STF following calcaneal ORIF.

CONCLUSION

Patients who ultimately require STF within 5 years of calcaneal ORIF had higher rates of alcohol abuse, tobacco use, drug use, obesity, and depression. There was no significant difference observed between those with and without STF in average same-day and 90-day reimbursements and demographics.

Effects of chronic ankle instability after grade I ankle sprain on the post-traumatic osteoarthritis

BACKGROUND

Untreated acute ankle sprains often result in chronic ankle instability (CAI) and can ultimately lead to the development of post-traumatic osteoarthritis (PTOA). At present, a typical animal model of ankle instability in mice is established by transecting the ligaments around the ankle joint. This study aimed to establish a grade I acute ankle sprain animal model by rapid stretching of peri-ankle joint ligaments. Furthermore, we tried to explore the pathophysiological mechanism of ankle osteoarthritis.

METHODS

In all, 18 male C57BL/6 J mice (7 weeks) were randomly divided into three groups: calcaneofibular ligament (CFL) laxity group, deltoid ligament (DL) laxity group, and SHAM group. One week after the surgical procedure, all mice were trained to run in the mouse rotation fatigue machine daily. The mice were tested on the balance beam before surgery and three days, 4 weeks, 8 weeks, and 12 weeks after surgery. Footprint analyses were performed on each mouse before surgery and 12 weeks after surgery. Micro-CT scanning was then performed to evaluate the degeneration of ankle joints and histological staining was performed to analyze and evaluate PTOA caused by ankle joint instability.

RESULTS

After surgery, the mice in the CFL and DL laxity groups took longer to cross the balance beam and slipped more often than those in the SHAM group (p < 0.05). The step length and width in the CFL and DL laxity groups were significantly shorter and smaller than those in the SHAM group 12 weeks after surgery (p < 0.05). There was a significant increase in the bone volume fraction (BV/TV) in the CFL and DL laxity groups compared with the SHAM group (p < 0.05). Histological staining results suggested obvious signs of PTOA in the CFL and DL laxity groups.

CONCLUSIONS

Based on CFL and DL laxity in a mouse ankle instability model, this study suggests that grade I ankle sprain can contribute to chronic ankle instability, impair motor coordination and balance, and eventually lead to PTOA of ankle with significant degeneration of its adjacent joints.

Randomized controlled trial on ankle biomechanics in the treatment of functional ankle instability with joint mobilization

Functional ankle instability (FAI) patients often experience restricted ankle dorsiflexion, increased inversion angle, and elevated ground reaction forces during walking, all related to altered kinematics of the talocrural and subtalar joints. This study aimed to investigate the potential positive impact of joint mobilization on FAI patients from a biomechanical perspective. The experimental group (EG, n = 17; Age: 20.06 ± 1.34 years; Height: 1.74 ± 0.07 m; Weight: 69.79 ± 11.20 kg; BMI:22.88 ± 2.63 kg/m2; CAIT:15.59 ± 2.58; M/F: 15/2) received joint mobilization + routine rehabilitation training, while the control group (CG, n = 16; Age: 20.50 ± 0.73 years; Height: 1.73 ± 0.09 m; Weight: 64.59 ± 7.21 kg; BMI: 21.65 ± 2.47 kg/m2; CAIT: 16.75 ± 2.21; M/F: 14/2) only received regular rehabilitation training. Biomechanical tests were performed in both groups after the 4-week intervention. The spatial parameters during walking (including step length, stride length, step width, step time, cadence, step speed, support time, and swing time), ankle flexion and dorsiflexion angle, inversion, and eversion angles, internal and external rotation angles, ankle torque, as well as the vertical ground reaction force were measured before and after the intervention. The results of the two-way ANOVA showed that the main effect of time was significant for step length (P < 0.001), stride length (P = 0.008), step speed (P < 0.001), the sagittal plane angle at touchdown (P < 0.001), maximum dorsiflexion angle (P = 0.005), sagittal plane toe off-ground angle (P < 0.001), peak flexion-dorsiflexion torque (P = 0.033), the first peak vGRF (P = 0.013), and second peak vGRF (P = 0.011). The main effect of Time * Group was significant for step speed (P = 0.044). The EG demonstrated significant improvements in step speed (P = 0.047), maximum dorsiflexion angle (P = 0.047), and the first peak vGRF (P = 0.028) compared to the CG. This study reveals that joint mobilization intervention enhances gait spatiotemporal parameters, kinematics, and kinetics, particularly in step speed, maximum dorsiflexion angle, and the first vGRF peak for the EG compared to the CG. Therefore, the rehabilitation strategy for patients with functional ankle instability should appropriately increase the use of joint movement to promote the functional recovery of FAI patients.

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.

Relationship between Joint and Ligament Structures of the Subtalar Joint and Degeneration of the Subtalar Articular Facet

This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angles were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Additionally, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.

A new mouse model of ankle instability induced by multiple mechanical sprains with controlled inversion angle and speed

Ankle sprain occurs by a sudden and extreme inversion and plantarflexion at the ankle joint to cause ligamentous injuries. A portion of ankle sprain patients experience recurrent ankle sprains and develop chronic ankle instability (CAI). The present CAI animal models are single events with severe ligamentous injury using surgical transection of ligaments or manually overextending the ankle.

Purpose: To simulate the mechanical and recurrent sprain injuries in CAI patients, we established a new ankle instability model with multiple ankle injuries using a self-designed machine to sprain the ankle with a controlled inversion angle and speed.

Methods: Male C57BL/6J mice were used and respectively subjected to a sham operation, calcaneofibular ligament (CFL) transection, and mechanical ankle sprains. Three mechanical sprains were performed on the 13th and 185th day after the initial mechanical ankle sprain.

Results: The first mechanical sprain and CFL transection induced ankle injury as indicated by an average of a 62% decrease in ankle pressure pain threshold and a 114% increase in the ankle thickness compared with the contralateral untreated ankle. The second and third mechanical sprains induced recurrent ankle injuries. The foot slips during beam tests were increased after mechanical ankle sprains but not after CFL transection, indicating the induction of motor balance deficits. Multiple mechanical ankle sprains induced significant gait changes in longer duration of stance (an average of 194% increase), swing (134%), and step cycle (147%) compared with CFL transection or sham operation, and slower walking speed (78% reduction) and shorter step distance (91%) after the third sprain.

Conclusion: These results elucidate that multiple mechanical sprains, which induce recurrent ankle injuries, balance deficits, and gait changes, are a good model for investigating the mechanisms of CAI induced by recurrent sprain injuries.

Exosomes derived from platelet-rich plasma administration in site mediate cartilage protection in subtalar osteoarthritis

Subtalar osteoarthritis (STOA) is often secondary to chronic ankle sprains, which seriously affects the quality of life of patients. Due to its etiology and pathogenesis was not studied equivocally yet, there is currently a lack of effective conservative treatments. Although they have been used for tissue repair, platelet-rich plasma-derived exosomes (PRP-Exo) have the disadvantage of low retention and short-lived therapeutic effects. This study aimed to determine whether incorporation of PRP-Exo in thermosensitive hydrogel (Gel) increased their retention in the joint and thereby playing a therapeutic role on STOA due to chronic mechanical instability established by transecting lateral ligaments (anterior talofibular ligament (ATFL)/calcaneal fibular ligament (CFL)). PRP-Exo incorporated Gel (Exo-Gel) system, composed of Poloxamer-407 and 188 mixture-based thermoresponsive hydrogel matrix in an optimal ratio, was determined by its release ability of Exo and rheology of Gel response to different temperature. The biological activity of Exo-Gel was evaluated in vitro, and the therapeutic effect of Exo-Gel on STOA was evaluated in vivo. Exo released from Exo-Gel continuously for 28 days could promote the proliferation and migration of mouse bone mesenchymal stem cells (mBMSCs) and chondrocytes, at the same time enhance the chondrogenic differentiation of mBMSCs, and inhibit inflammation-induced chondrocyte degeneration. In vivo experiments confirmed that Exo-Gel increased the local retention of Exo, inhibited the apoptosis and hypertrophy of chondrocytes, enhanced their proliferation, and potentially played the role in stem cell recruitment to delay the development of STOA. Thus, Delivery of PRP-Exo incorporated in thermosensitive Gel provides a novel approach of cell-free therapy and has therapeutic effect on STOA.

Graphical Abstract