Absence of ATFL remnant does not affect the clinical outcomes of the modified broström operation for chronic ankle instability

Predictive Modeling for Functional Outcomes After All-Inside Arthroscopic Anterior Talofibular Ligament Repair of Chronic Ankle Instability

BACKGROUND

Arthroscopic anterior talofibular ligament repair (AATFLR) is a surgical strategy to treat chronic ankle instability (CAI) patients. This study identified risk factors that influenced the functional outcomes of AATFLR for CAI and developed prognostic nomogram for predicting functional outcomes in future AATFLR cases.

METHODS

Patients undergoing AATFLR from January 2016 to June 2022 with at least 10 months of follow-up were included in the study. The Karlsson Ankle Functional Score (KAFS) was evaluated preoperatively and at last follow-up visit. A total of 15 potential predictors including age, sex, body mass index, side affected, time from injury to surgery, sports-related injury, osteophyte, loose bodies, distal tibiofibular syndesmosis, ATFL avulsion fracture, Outerbridge classification of osteochondral lesions, postoperative immobilization method, ambulation time, walking time, and follow-up time, were recorded. We first used univariate binary logistic regression analysis to select the potential significant prognostic features, which were then subjected to the least absolute shrinkage and selection operator (LASSO) regression algorithm for final feature selection. A nomogram based on the regression model was developed to estimate the functional outcomes of patients. Models were validated internally using bootstrapping and externally by calculating their performance on a validation cohort.

RESULTS

Overall, 200 ankles fit inclusion criteria. Of these 200, a total of 185 (92.5%) ankles were eligible and divided into development (n = 121) and validation (n = 64) cohorts. Four predictors were ultimately included in the prognostic nomogram model: age, sex, sports-related injury, and postoperative immobilization method.

CONCLUSION

We found in our cohort that the significant predictors of poorer functional outcomes of AATFLR were postoperative immobilization with lower-leg cast, female sex, non-sports-related ankle sprain, and increasing age. Prognostic nomograms were created.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Enhancing Post-Surgical Rehabilitation Outcomes in Patients with Chronic Ankle Instability: Impact of Subtalar Joint Axis Balance Exercises Following Arthroscopic Modified Broström Operation

Background and Objectives: This study aimed to evaluate the effects of subtalar joint axis-based balance exercises on the anterior talofibular ligament (ATFL) thickness, ankle strength, and ankle stability after an arthroscopic modified Broström operation (AMBO) for chronic ankle instability (CAI). Materials and Methods: The study included 47 patients diagnosed with CAI who underwent AMBO and were randomly divided into three groups: control (n = 11), general balance exercise (n = 17), and subtalar joint axis balance exercise (n = 19), regardless of the affected area. Participants in the exercise rehabilitation group performed exercises for 60 min twice a week for six weeks, starting six weeks after AMBO. ATFL thickness, ankle strength, and ankle dynamic stability were measured using musculoskeletal ultrasonography, Biodex, and Y-balance test, respectively, before and after treatment. Results: Compared with the remaining groups, the subtalar joint axis balance exercise group had reduced ATFL thickness (p = 0.000), improved ankle strength for eversion (p = 0.000) and inversion (p = 0.000), and enhanced ankle stability (p = 0.000). Conclusions: The study results suggest that subtalar joint axis-based balance exercises may contribute to the early recovery of the ankle joint after AMBO.

Anatomical study of the bone morphology of the anterior talofibular ligament attachment

Anterior talofibular ligament (ATFL) injuries are the most common cause of ankle sprains. To ensure anatomically accurate surgery and ultrasound imaging of the ATFL, anatomical knowledge of the bony landmarks around the ATFL attachment to the distal fibula is required. The purpose of the present study was to anatomically investigate the ATFL attachment to the fibula with respect to bone morphology and attachment structures. First, we analyzed 36 feet using microcomputed tomography. After excluding 9 feet for deformities, the remaining 27 feet were used for chemically debrided bone analysis and macroscopic and histological observations. Ten feet of living specimens were observed using ultrasonography. We found that a bony ridge was present at the boundary between the attachments of the ATFL and calcaneofibular ligament (CFL) to the fibula. These two attachments could be distinguished based on a difference in fiber orientation. Histologically, the ATFL was attached to the anterodistal part of the fibula via fibrocartilage anterior to the bony ridge indicating the border with the CFL attachment. Using ultrasonography in living specimens, the bony ridge and hyperechoic fibrillar pattern of the ATFL could be visualized. We established that the bony ridge corresponded to the posterior margin of the ATFL attachment itself. The ridge was obvious, and the superior fibers of the ATFL have directly attached anteriorly to it. This bony ridge could become a valuable and easy-to-use landmark for ultrasound imaging of the ATFL attachment if combined with the identification of the fibrillar pattern of the ATFL.

Ankle Sprains in Athletes: Current Epidemiological, Clinical and Imaging Trends

Purpose

Ankle injuries are frequent sports injuries. Despite optimizing treatment strategies during recent years, the percentage of chronification following an ankle sprain remains high. The purpose of this review article is, to highlight current epidemiological, clinical and novel advanced cross-sectional imaging trends that may help to evaluate ankle sprain injuries.

Methods

Systematic PubMed literature research. Identification and review of studies (i) analyzing and describing ankle sprain and (ii) focusing on advanced cross-sectional imaging techniques at the ankle.

Results

The ankle is one of the most frequently injured body parts in sports. During the COVID-19 pandemic, there was a change in sporting behavior and sports injuries. Ankle sprains account for about 16-40% of the sports-related injuries. Novel cross-sectional imaging techniques, including Compressed Sensing MRI, 3D MRI, ankle MRI with traction or plantarflexion-supination, quantitative MRI, CT-like MRI, CT arthrography, weight-bearing cone beam CT, dual-energy CT, photon-counting CT, and projection-based metal artifact reduction CT may be introduced for detection and evaluation of specific pathologies after ankle injury. While simple ankle sprains are generally treated conservatively, unstable syndesmotic injuries may undergo stabilization using suture-button-fixation. Minced cartilage implantation is a novel cartilage repair technique for osteochondral defects at the ankle.

Conclusion

Applications and advantages of different cross-sectional imaging techniques at the ankle are highlighted. In a personalized approach, optimal imaging techniques may be chosen that best detect and delineate structural ankle injuries in athletes.

Outcomes of a novel all-inside arthroscopic anterior talofibular ligament repair for chronic ankle instability

PURPOSE

This study aimed to introduce a novel all-inside arthroscopic anterior talofibular ligament (ATFL) repair for chronic ankle instability (CAI) with a knotless suture anchor technique-Hugging Repair, evaluate clinical outcomes, and analyze the associated risk factors.

METHODS

A total of 84 patients (42 males and 42 females, mean age: 36.1 ± 11.2 years, range: 19-68 years) who underwent Hugging Repair from January 1, 2016 to December 31, 2018, were enrolled in this retrospective study. The American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson Ankle Functional Score (KAFS), Foot and Ankle Outcome Score (FAOS), Tegner score, and Numerical Rating Scale (NRS) were evaluated pre-operatively and at final follow-up. The potential risk factors such as age, body mass index (BMI), sex, post-injury duration (time from injury to surgery), follow-up time, number of anchors, concomitant injuries [e.g., osteochondral defects (OCD), sinus tarsi syndrome (STS), anterior ankle impingement (AAI)], first-time treatment, and number of ankle sprains were also analyzed through multiple regression analysis.

RESULTS

There were 68 (81%) patients followed up for a mean time of 42 (range: 35-50) months. The median AOFAS score increased from 65 (35-72) to 90 (77-100), KAFS increased from 64 (38-71) to 90 (62-100), FAOS increased from 68 (50-70) to 97 (68-100), Tegner score increased from 1 (1-3) to 4 (2-7), and NRS increased from 3.5 (2-5) to 1 (0-3). No correlation was found between the functional scores and risk factors mentioned above. In the multivariate model, age was significantly negatively associated with KAFS, FAOS, and Tegner activity scale (P = 0.013; P = 0.002; P = 0.000); female was significantly associated with poorer Tegner activity scale (P = 0.004); and the presence of concomitant injuries was significantly negatively associated with AOFAS score (P = 0.033).

CONCLUSION

The novel all-inside arthroscopic ATFL repair for CAI with a knotless suture anchor technique-Hugging Repair is a safe and suitable technique that achieves satisfactory clinical outcomes and provides an effective option for the treatment of CAI. Risk factors for patients who underwent all-inside ATFL repair were older age, female sex, and concomitant injuries.

Anterior talofibular ligament remnant quality is important for achieving a stable ankle after arthroscopic lateral ankle ligament repair

PURPOSE

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

IV.

Characteristics of Chronic Ankle Instability Requiring Both Anterior Talofibular and Calcaneofibular Ligament Repair

Chronic ankle instability (CAI) leads to the ankle osteoarthritis (OA), and ligament repair is performed to restore ankle stability. However, anterior talofibular ligament (ATFL) repair alone is not sufficient to stabilize the ankle in some cases, which additionally require calcaneofibular ligament (CFL) repair. This study aimed to explore characteristics of CAI that necessitated the repair of both ATFL and CFL. Forty-three patients (44 ankles) with CAI treated operatively were retrospectively reviewed. After ATFL repair, patients with residual ankle instability revealed by the varus stress under fluoroscopy additionally underwent CFL repair. Preoperative condition and intraoperative findings of the combined ATFL and CFL repair (AC) (n = 24) and only ATFL repair (A) (n = 20) groups were compared. The ankle activity score of group AC was significantly higher (p < .05) than that of group A. OA changes at the medial gutter were observed in 62.5% (15/24) in the group AC and 20% (4/20) in group A. Chondral/osteochondral lesions were seen in 66.7% (16/24) in the group AC and 20% (4/20) in group A. The remnant quality in group AC was inferior to that of group A. CAI that necessitated both ATFL and CFL repair exhibited characteristic findings such as high ankle activity score, high rate of chondral/osteochondral lesions and/or OA changes, and poor quality of ATFL remnants compared to those in CAI that required only ATFL repair. The repair of both ATFL and CFL should be considered in CAI which exhibit these characteristics to ensure complete correction of the instability.

The ALR-RSI score is a valid and reproducible scale to assess psychological readiness before returning to sport after modified Broström-Gould procedure

PURPOSE

Psychological readiness scores have been developed to optimize the return to play in many sports-related injuries. The purpose of this study was to statistically validate the ankle ligament reconstruction-return to sport injury (ALR-RSI) scale after modified Broström-Gould (MBG) procedure.

METHODS

A similar version of the ACL-RSI scale with 12 items was adapted to quantify the psychological readiness to RTS after MBG and to describe construct validity, discriminant validity, feasibility, reliability and internal consistency of the scale, according to the COSMIN methodology. The term "knee" was replaced by "ankle". The AOFAS and Karlsson scores were used as references patient-related outcome measurements (PROMs).

RESULTS

A total of 71 patients were included. The ALR-RSI score after MBG procedure was highly (r > 0.5) correlated to the AOFAS and Karlsson scores, with a Pearson coefficient r = 0.69 [0.54-0.80] and 0.72 [0.53-0.82], respectively. The mean ALR-RSI score was significantly greater in the subgroup of 55 patients who resumed sports activity compared to those that no longer practiced sport: 61.9 (43.8-79.6) vs 43.4 (25.0-55.6), (p = 0.01). The test-retest showed an "excellent" reproducibility with a ρ intraclass correlation coefficient of 0.93 [0.86-0.96]. The Cronbach's alpha statistic was 0.95, attesting an "excellent" internal consistency between the 12 ALR-RSI items.

CONCLUSION

The ALR-RSI score is a valid and reproducible tool for the assessment of psychological readiness to RTS after an MBG procedure for the management of CLAI, in a young and active population. The ALR-RSI score may help to identify and counsel athletes on their ability to return to sport.

LEVEL OF EVIDENCE

III.

Percutaneous Inferior Extensor Retinaculum Augmentation Technique for Chronic Ankle Instability

OBJECTIVE

To specify indications and contraindications of the modified percutaneous inferior extensor retinaculum augmentation (PIERA) technique for chronic ankle instability cases, and to introduce technique details and report surgical outcomes and complications.

METHODS

The PIERA technique was performed on seven patients with chronic ankle instability (four females and three males, 36.4 ± 15.1 years of age, and course of symptoms of 33.7 ± 8.8 months) from June to October 2018 in this retrospective study of case series. All patients demonstrated attenuated ligamentous tissue quality, which was confirmed using preoperative ankle MRI. IER were drew up to the distal fibula using suture anchors with the ankle in neutral position for all cases, to engage the entire IER in reconstructing the stability of the ankle. Patients were assessed using American Orthopaedic Foot and Ankle Society Ankle-Hindfoot (AOFAS) score and Cumberland Ankle Instability Tool (CAIT) scores pre- and postoperatively at the last follow-up examination. Preoperative and postoperative outcome scores of patients were compared using paired t-test. A p value of less than 0.05 was regarded statistically significant.

RESULTS

Mean follow-up duration was 16.7 ± 1.6 months. The mean AOFAS score significantly improved from 66.9 ± 11.2 preoperatively to 93.7 ± 8.5 postoperatively (P = 0.001). Mean CAIT score significantly improved from 13.1 ± 4.7 preoperatively to 26.3 ± 1.8 postoperatively (P = 0.001). Patients did not report any wound healing problem, numbness, swelling, or instability at the last follow-up examination, except for one patient who reported pain and minimal stiffness, and presented an AOFAS score of less than 80 and a CAIT score below 24. All patients returned to at least recreational sport activity level.

CONCLUSION

The PIERA technique can improve the functional outcomes of patients with chronic ankle instability with few complications.

Additional Inferior Extensor Retinaculum Augmentation After All-Inside Arthroscopic Anterior Talofibular Ligament Repair for Chronic Ankle Instability Is Not Necessary

BACKGROUND

Although several arthroscopic surgical techniques for the treatment of chronic ankle instability (CAI) have been introduced recently, the effect of inferior extensor retinaculum (IER) augmentation remains unclear.

PURPOSE

To compare the clinical outcomes after arthroscopic anterior talofibular ligament (ATFL) repair according to whether additional IER augmentation was performed or not.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We performed a retrospective review of consecutive patients who underwent arthroscopic ATFL repair surgery for CAI between 2016 and 2018. The mean age of the patients was 35.2 years (range, 19-51 years), and the mean follow-up period was 32.6 months (range, 24-48 months). Patients were divided into 2 groups according to the surgical technique used for CAI: arthroscopic ATFL repair (group A; n = 37) and arthroscopic ATFL repair with additional IER augmentation (group R; n = 45). The pain visual analog scale, American Orthopaedic Foot & Ankle Society score, Foot and Ankle Outcome Score, and the Karlsson Ankle Function Score were measured as subjective outcomes, and posturographic analysis was performed using a Tetrax device as an objective outcome. Radiologic outcome evaluations were performed preoperatively and at 2 years postoperatively using stress radiographs and axial view magnetic resonance imaging (MRI).

RESULTS

Out of 101 patients, 19 (18.5%) were excluded per the exclusion criteria, and 82 were evaluated. We identified 6 retears (7.3%) based on postoperative MRI evaluation. All patients who had ATFL retear on MRI (8.1% [3/37] in group A and 6.7% [3/45] in group R) demonstrated recurrent CAI with functional discomfort and anterior displacement >3 mm as compared with the intact contralateral ankle. All clinical scores and posturography results were improved after surgery in both groups (P < .001). However, there were no significant differences in the clinical results and radiologic findings between the groups.

CONCLUSION

The clinical and radiologic outcomes of patients with CAI improved after all-inside arthroscopic ATFL repair. However, additional IER augmentation after arthroscopic ATFL repair did not guarantee better clinical outcomes.

The signal intensity of preoperative magnetic resonance imaging has predictive value for determining the arthroscopic reparability of the anterior talofibular ligament

PURPOSE

Arthroscopic all-inside anterior talofibular ligament (ATFL) repair is a common surgical technique for chronic ankle instability (CAI), and the condition of the ATFL remnants is associated with its reparability. ATFL reparability can affect the clinical course, but the relationship between magnetic resonance imaging (MRI) findings and the intraoperative ATFL reparability is still unclear. The purpose of this study was to investigate the relationship between ATFL signal intensities according to MRI and intraoperative ATFL reparability.

METHODS

This study included 55 cases of CAI (n = 37) and osteochondral lesion of the talus (n = 18) that underwent MRI followed by subsequent arthroscopy. MRI signal intensity was measured preoperatively to calculate the signal to noise ratio (SNR). During arthroscopy, the presence of an ATFL tear was checked and the ATFL tension was classified as taut, mild laxity, or laxity; ATFL quality was classified as excellent (normal), moderate (abnormal but reparable), or poor (irreparable). It was then analyzed whether there was a relationship between the intraoperative findings and the SNR.

RESULTS

The mean SNR was 23.4 ± 21.6. The SNR was significantly different according to the presence of an ATFL tear and ATFL tension and quality (all P = 0.001). The SNR was better correlated with ATFL quality (r = 0.708) than the presence of a tear (r = 0.545) or degree of tension (r = 0.653). The diagnostic SNR cutoff point to distinguish a normal ATFL from an abnormal but reparable ATFL was 11.2, and that to distinguish between an irreparable and reparable ATFL, was 32.3.

CONCLUSION

The SNR, representing MRI signal intensities, is highly correlated with the intraoperative measures of the ATFL. Therefore, the SNR had predictive value for determining the arthroscopic reparability of the ATFL.

LEVEL OF EVIDENCE

Level III.

All-Inside Arthroscopic Modified Broström Technique to Repair Anterior Talofibular Ligament Provides a Similar Outcome Compared With Open Broström-Gould Procedure

PURPOSE

To introduce an all-inside modified Broström technique to suture the anterior talofibular ligament (ATFL) and inferior extensor retinaculum (IER) under arthroscopy and to compare its outcomes with those of the conventional open procedure.

METHODS

All patients who underwent arthroscopic or open repair of the ATFL between June 2014 and December 2017 were included in this study. Visual analog scale (VAS), Karlsson and Peterson (K-P), American Orthopedic Foot and Ankle Society (AOFAS) ankle/hindfoot, and Tegner activity scores, as well as manual anterior drawer test (ADT), were used to evaluate the patients preoperatively and ≥2 years after surgery. The Sefton grading system was used to assess the level of satisfaction after surgery. Detailed surgical data and intraoperative findings were documented at the time of surgery.

RESULTS

A total of 67 patients, 31 in the arthroscopic group and 36 in the open group, were included in this study (43 men and 24 women, mean body mass index 24.00, range 19.53 to 30.03). The surgical duration in the arthroscopic group (median, 34 minutes; range, 25 to 74) was significantly shorter than that in the open group (mean, 43.08 ± 8.11 minutes; 95% confidence interval [CI] 40.34 to 45.83) (P = .007). At the last follow-up, the subjective functional scores and ADT results improved significantly in both cohorts (P < .001). However, no significant difference was found in the VAS score (1.74 ± 1.24, 95% CI 1.29 to 2.2, in the open group versus 1.58 ± 1.2, 95% CI 1.18 to 1.99, in the arthroscopic group; P = .581), AOFAS score (91.71 ± 5.46, 95% CI 89.71 to 93.71, versus 90.67 ± 5.59, 95% CI 88.78 to 92.56; P = .444), K-P score (87.52 ± 7.59, 95% CI 84.73 to 90.3, versus 88.75 ± 5.56, 95% CI 86.87 to 90.63; P = .446), and ADT evaluation (normal: 96.77% versus 94.44%, P = .557) between the arthroscopic and open groups, respectively. In addition, 28 cases (90.32%) in the arthroscopic group and 32 (88.89%) in the open group achieved satisfactory results based on the Sefton grading system (P = .736). Seventeen patients (47.2%) in the open group and 18 patients (58.1%) in the arthroscopic group underwent Tegner evaluation after surgery, which showed no significant difference (5, interquartile range [IQR] 1 in the open group versus 5, IQR 3 in the arthroscopic group; P = .883). Complications were reported in 4 (11.1%) and 2 (6.5%) patients who underwent open and arthroscopic surgeries, respectively (P = .813).

CONCLUSIONS

Both open and arthroscopic modified Broström surgeries generated favorable outcomes, with a significant improvement compared with the preoperative condition. Compared with the open Broström-Gould procedure, the all-inside arthroscopic modified Broström technique produced equivalent functional and clinical results at a minimum of 2 years after the operation, with a shorter surgical duration. Arthroscopic repair might be a safe and viable alternative to open surgery for lateral ankle stabilization.

LEVEL OF EVIDENCE

III.

Open Brostrom for Lateral Ligament Stabilization

PURPOSE OF REVIEW

Lateral ankle ligament sprains are one of the most commonly reported injuries in high-level athletes and the general population. Unfortunately, up to 40% of these can go on to develop chronic lateral ankle instability which in the right circumstances requires surgical intervention. The purpose of this review is to present the gold standard surgical treatment for chronic lateral instability with anatomic ligament repair and to highlight the techniques, outcomes, and importance of anatomy when considering surgical treatment.

RECENT FINDINGS

Recent and remote literature agrees that the initial treatment for chronic ankle instability is non-operative rehabilitation. In the cases where this fails, the gold standard of surgical treatment is open anatomic repair using the Brostrom-Gould technique which stands out as having very good results over the course of time. Recent studies have shown equally good outcomes with arthroscopy as well as with internal brace devices, and both techniques show potential for earlier rehabilitation. In those with contraindications for anatomic repair including innate soft tissue laxity, high BMI, and in the revision setting, anatomic ligament reconstruction is an appropriate surgical option. Open modified Brostrom lateral ligament repair continues to be the preferred method of surgical treatment for chronic lateral ligament instability. In the setting of new modifications and techniques, long-term outcome studies are necessary to identify both their usefulness in long term and to compare them to the open surgery outcomes. It would be useful to standardize rehabilitation protocols as well as return to sport metrics in order to better evaluate outcomes moving forward.

Bone Mineralization Changes in the Subchondral Bone of the Medial Gutter in Chronic Lateral Ankle Instability

BACKGROUND

Chronic ankle instability (CAI) induces osteoarthritis (OA) by inflicting abnormal stresses on the medial gutter. It is important to detect early OA change and to explore factors likely to induce the OA. The purpose of this study was to evaluate subchondral bone change in the medial gutter of CAI using computed tomography (CT) scans.

METHODS

Thirty-five ankles with CAI (CAI group) and 35 ankles without CAI (control group) were included. The region of interest (ROI) in the subchondral bone of the medial gutter on CT axial images was set on the tibia and talus. The Hounsfield unit (HU) in ROIs was measured and corrected by the HU of the fibula in the same slice. HU ratios were compared between the CAI and control groups. In the CAI group, the relationship between the HU ratio and the talar tilt angle (TTA), OA change, and the anterior talofibular ligament (ATFL) remnant quality were analyzed.

RESULTS

The mean HU ratio in the CAI group was significantly higher than that in the control. In the CAI group, HU ratios in ≥10 degrees of TTA were significantly higher than those in <10 degrees. But there was no significant difference in the HU ratios with or without OA change in the medial gutter. A good-quality ATFL remnant showed a low HU ratio compared with that with poor quality.

CONCLUSION

CAI patients exhibited subchondral bone change in the medial gutter, which suggests that the elimination of instability may help to prevent or decrease the development and/or progression of osteoarthritis.

LEVEL OF EVIDENCE

Level III, comparative series.