The platelet-rich plasma (PRP) approach may be an effective treatment for joint and cartilage pathologies. However, the rationale for its effectiveness on joint instability is limited. This study aimed to assess the safety and effectiveness of PRP injections in patients with chronic lateral ankle instability (CLAI). This retrospective study was performed at a single-center outpatient clinic between January 2015 and February 2023 and included pre-intervention assessment and short-term follow-up. Patients were excluded if they had received previous surgical treatment or had constitutional hyperlaxity, systemic diseases, or grade II or III osteoarthritis. The clinical and functional evaluation consisted of the Karlsson score, the Cumberland Ankle Instability Tool (CAIT), Good\'s grading system, the patient\'s subjective satisfaction level, and the time required to return to exercise. The entire PRP therapy regime consisted of three PRP administrations at 7-day intervals and follow-up appointments. PRP was administered both intraarticularly and into talofibular ligaments. A total of 47 consecutive patients with CLAI were included, 11 were female (23.4%), with a mean age at intervention of 31.19 ± 9.74 years. A statistically significant improvement was found in the CAIT and Karlsson scores at 3 months (27.74 ± 1.68 and 96.45 ± 4.28, respectively) relative to the pre-intervention status (10.26 ± 4.33 and 42.26 ± 14.9, respectively, p < 0.000). The mean follow-up of patients with CLAI was 17.94 ± 3.25 weeks. This study represents successful short-term functional and clinical outcomes in patients with CLAI after PRP treatment, with no adverse effects. It demonstrates the feasibility of a randomized controlled trial to further assess this therapy.

Introduction This paper aims to report the incidence of ligamentous, tendon, and other structural injuries associated with an anterior talofibular ligament (ATFL) injury based on magnetic resonance imaging (MRI) findings. Methods The reports of all patients who underwent surgical treatment for ATFL injury between 2021 and 2022 at Changi General Hospital and had preoperative MRI ankle scans performed were analyzed in this retrospective study. Patients who had a preoperative MRI ankle scan performed with specific reporting of the ATFL, calcaneofibular ligament (CFL), deltoid ligaments, peroneal tendons, and the presence of an osteochondral defect (OCD) were included in this study. Patients who underwent surgery but did not have a preoperative MRI ankle scan done or had ankle fractures or systemic conditions affecting the same ankle were excluded. Results Eighty-six patients were included in this study, of which 59 were males and 27 were females. About 73.3% (63 of 86) of patients had sustained injuries in association with ATFL injury, and 58.1% (50 of 86) of patients suffered an associated injury to the calcaneofibular ligament (CFL). There were injuries to the superficial and deep deltoid ligaments in 29.1% (25 of 86) and 44.2% (38 of 86) of patients, respectively. The peroneal tendons were also injured in 17.4% (15 of 86) of patients. Lastly, there were also associated OCDs found in 19.8% (17 of 86) of patients. Conclusion There is a high incidence of injuries associated with an ATFL injury. The CFL and deltoid ligament complex are the most commonly injured structures in association with the ATFL. One in five patients will also have an associated OCD. The ATFL tends to be the only structure that is commonly addressed during surgery. Repair of the ATFL only may thus lead to poorer outcomes and persistent pain, if the underlying cause is due to the other concurrent injuries. Clinical evaluation of the other structures should thus be thoroughly performed to allow the addressing of any concurrent injuries in the same surgical setting to achieve better outcomes.

Hindfoot varus deformity is a known risk factor for chronic lateral ankle instability (CLAI). The impact of this deformity on clinical results following arthroscopic lateral ankle ligament repair (ALLR) for CLAI has not been studied.
Sixty-three ankles from 62 patients who received ALLR for CLAI were retrospectively examined. Preoperative plain radiographs were used to measure tibial articular surface (TAS) angles, and long axial hindfoot alignment radiographs were used to measure tibiocalcaneal angles (TCAs) pre- and postoperatively. Results included ratings on the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) and recurrent ankle instability (respraining of the operated ankle following surgery).
Recurrent ankle instability, defined as incidence of any new ankle sprain after surgery reported in the follow-up period, occurred in 13 ankles. The TAS angles of these patients were significantly low, and their preoperative TCA was significantly high. Multivariate analysis showed that preoperative TCA was an independent risk factor for recurrent ankle instability. The threshold values for preoperative TCA for recurrent instability were determined via the receiver operating characteristic curve analysis to be 3.4 degrees. Patients were assigned to a low- or high-TCA group based on the reported average TCA (2.7 degrees) of healthy patients. In the high-TCA group, recurrent instability was significantly more frequent, and the scores on the pain subscale of the postoperative SAFE-Q were significantly lower.
Hindfoot varus alignment was associated with pooreroutcomes after ALLR.
Level III, retrospective comparative study.

OBJECTIVE: The relationship between ligament remnant quality and postoperative outcomes after arthroscopic lateral ankle ligament repair for chronic lateral ankle instability is controversial. This study aimed to determine whether the signal intensity of the anterior talofibular ligament on preoperative magnetic resonance imaging and ligament remnant quality identified on arthroscopy are associated with recurrent ankle instability after arthroscopic lateral ankle ligament repair.
METHODS: A total of 68 ankles from 67 patients with chronic lateral ankle instability who underwent arthroscopic lateral ankle ligament repair were retrospectively studied. The signal intensity of the anterior talofibular ligament was evaluated using T2-weighted magnetic resonance imaging. Arthroscopy was used to evaluate the thickness and mechanical resistance of the anterior talofibular ligament by hook palpation and to classify ankles into two groups: the present anterior talofibular ligament group with adequate mechanical resistance and the absent anterior talofibular ligament group with no mechanical resistance. The outcomes included recurrent ankle instability (respraining of the operated ankle after surgery) and Self-Administered Foot Evaluation Questionnaire scores.
RESULTS: Thirteen ankles were diagnosed with recurrent ankle instability. Patients with a high anterior talofibular ligament T2 signal intensity experienced more recurrent ankle instability than those with a low intensity. As determined via arthroscopy, the absent anterior talofibular ligament group had a higher rate of recurrent ankle instability than the present anterior talofibular ligament group. There were no significant differences in Self-Administered Foot Evaluation Questionnaire scores between patients with high and low anterior talofibular ligament T2 signal intensity, as well as between absent and present anterior talofibular ligament groups based on arthroscopy.
CONCLUSIONS: Poor quality of the anterior talofibular ligament remnant could result in recurrent ankle instability after arthroscopic lateral ankle ligament repair. Therefore, when treating chronic lateral ankle instability, surgeons should consider ligament quality.
METHODS: IV.

Although varus-tilted distal tibial deformity is an established risk factor for chronic lateral ankle instability (CLAI), no studies have reported whether this deformity influences ankle instability after arthroscopic lateral ankle ligament repair (ALLR) for CLAI.
A total of 57 ankles from 57 patients who underwent ALLR for CLAI were retrospectively analyzed. Tibial articular surface (TAS) angles were measured on preoperative plain radiograph. After 12 months of follow-up, recurrent ankle instability and talar tilt angles on stress radiograph were evaluated as outcomes. Relationships between the TAS angle and these outcomes were assessed.
Recurrent ankle instability was observed in 10 ankles. The TAS angles of patients with recurrent instability were significantly lower (85.2 degrees vs 87.9 degrees). The receiver operating characteristic curve analysis revealed that the cutoff value of TAS angle for recurrent instability was 86.2 degrees. Based on this cutoff value, our patients were divided into 2 groups: low-TAS and high-TAS group. Univariate and multivariate analysis revealed that low TAS was an independent risk factor for recurrent ankle instability and greater postoperative talar tilt angles.
Varus-tilted distal tibial plafond appears to be a risk factor for recurrent ankle instability after ALLR.

OBJECTIVE: This study evaluated the angular kinematic and moment of the ankle and foot during shod walking and barefoot walking in individuals with unilateral chronic ankle instability (CAI).
METHODS: Recreational soccer players with unilateral CAI were recruited for this cross sectional study conducted between January and August 2019. A total of 40 participants were screened for eligibility but only 31 met the inclusion criteria based on the methods of Delahunt et al and Gribble et al. Except for 3 participants not attending the evaluation session, 28 participants were finally included. A three dimensional motion analysis system made up of ProReflex motion capture unit and an AMTIb Kistler force plate, embedded in the middle of nine meter walkway, were used to assess the ankle and foot angles and moment during shod walking and barefoot walking conditions. A Statistical Package for Social Sciences (version 20.0) was used to analyze data.
RESULTS: During shod walking, the ankle joint plantar-flexion range of motion (ROM) at 10% of the gait cycle (GC) and dorsiflexion ROM at 30% of the GC were significantly higher than those during barefoot walking for both feet (p = 0.001, 0.001, 0.027, and 0.036 respectively). The inversion ROM during shod walking was significantly higher than that during barefoot walking for both feet at 10% and 30% of the GC (p = 0.001. 0.001, 0.001, and 0.042 respectively). At 10% of the GC, the eversion moment was significantly higher between barefoot and shod walking for both feet (both p = 0.001). At 30% of the GC, there was no significant difference between shod and barefoot walking plantar-flexion moment of both feet (p = 0.975 and 0.763 respectively), and the eversion moment of both feet (p = 0.116 and 0.101 respectively).
CONCLUSIONS: At the early stance, shod walking increases the ankle plantar-flexion and foot inversion ROM, and decreases the eversion moment for both feet in subjects with unilateral CAI. Therefore, the foot wearing condition should be considered during evaluation of ankle and foot kinematics and kinetics.

OBJECTIVE: To compare proprioception, postural stability, and neuromuscular control between patients with mechanical laxity and recurrent ankle sprain.
METHODS: Among 86 patients with ankle instability, 45 patients had mechanical laxity (mean age 27.2 ± 7.0 years) and 41 had recurrent ankle sprain (mean age 25.1 ± 9.2 years). Both the affected and unaffected ankles of each patient were evaluated. Proprioception and neuromuscular control tests were conducted using an isokinetic machine, and postural stability was tested using a postural stabilometry system.
RESULTS: Proprioception was not significantly different between the unaffected or affected ankles of the mechanical laxity group compared with those of the recurrent ankle sprain group (n.s). Static and dynamic postural stability and neuromuscular control were similar in the affected ankles between the two groups (n.s). However, postural stability (static, overall: p = 0.009, anterior-posterior: p = 0.028, medial-lateral: p = 0.022; dynamic, overall: p = 0.012, anterior-posterior: p = 0.004, medial-lateral: p = 0.001) and neuromuscular control (inversion: p = 0.031, eversion: p = 0.039, dorsiflexion: p = 0.029, plantarflexion: p = 0.035) were significantly decreased in the unaffected ankles of the recurrent ankle sprain group compared with those of the mechanical laxity group.
CONCLUSIONS: The unaffected ankles of the recurrent ankle sprain group showed significant decreases in both postural stability and neuromuscular control compared with the mechanical laxity group. Clinicians and therapists should consider unaffected ankle rehabilitation in patients with recurrent ankle sprain to prevent future sprain events.
METHODS: Case-control study, III.

OBJECTIVE: We previously reported that suppressive middle latency cutaneous reflexes (MLRs) in the peroneus longus (PL) are exaggerated in subjects with chronic ankle instability, and the changes are related to functional instability. However, the time-varying history of these neurophysiological changes after an ankle sprain is yet to be elucidated. Therefore, in the present study, we investigated the time course of the changes in the PL MLR after an ankle sprain in relation to the number of sprain recurrences.
METHODS: Twenty-three subjects with ankle sprain were classified into 3 groups according to their history of ankle sprain: first ankle sprain, 2-3 ankle sprains, and ≥4 ankle sprains. Twenty-three age-matched control subjects also participated. The PL MLRs were elicited by stimulating the sural nerve while the subjects performed different levels of isometric ankle eversion. Gain of MLR was estimated using linear regression analysis (slope value) of the amplitude modulation of MLRs obtained from graded isometric contractions.
RESULTS: The gain of MLRs first increased 4 weeks after the injury. In subjects with their first ankle sprain, the MLRs returned to almost baseline levels after 3 months. In contrast, the increase in MLR gain persisted even after 3 months in subjects with recurrent ankle sprains. In addition, the MLR gains were closely related to functional recovery of the ankle joint.
CONCLUSIONS: Our findings suggest that the recovery process of MLR gains were strongly affected by the history of ankle sprains as well as the functional recovery of the ankle joint.

[Purpose] This study aimed to investigate the postural control characteristics of individuals with and without a history of ankle sprain during single-leg standing by examining the relationship between various parameters of center of pressure (COP) and head and foot acceleration. [Subjects] Twenty subjects with and 23 subjects without a history of ankle sprain (sprain and control groups, respectively) participated. [Methods] Mean and maximum COP velocity and maximum COP range in the anteroposterior and mediolateral components of movement were calculated using a gravicorder. The anteroposterior and mediolateral maximum accelerations of the head and foot, as well as the root mean square (RMS) of each acceleration parameter, were measured using accelerometers. [Results] In the mediolateral component, a significant positive correlation was found between maximum acceleration of the foot and all COP parameters in the sprain group. [Conclusion] Our findings suggest that mediolateral momentary motion of the foot in individuals with a history of ankle sprain has relevance to various parameters of COP.

Individuals with chronic ankle instability (CAI) usually experience deficits in balance control, which increase displacement in the body\'s center of pressure (COP) when they balance on a single leg. Little is known, however, about whether or not these individuals use the strategies of postural adjustment properly, especially during functional tasks that may predispose them to ankle sprain. The aim of this study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with and without CAI as they kick a ball while standing in a single-leg stance with their ankle in neutral and supinated positions. COP displacements were calculated and their magnitudes (range) analyzed during APA and CPA intervals and over the duration of the whole task, represented by the COP area of sway and mean velocity. The CAI group exhibited a significant decrease in CPA and area of sway over the whole task, relative to controls. These results suggest that the decreased balance sway could be caused by the need for further stabilization of the ankle in more unstable postures to prevent recurrent sprain. Our findings could help clinicians to better understand the strategies of postural adjustments in individuals with CAI, and may assist and motivate new investigations into balance control interventions in such individuals, as well as proactively address recurrent ankle sprain conditions.