An interventional study of Arthroscopic Anterior Talofibular Ligament Repair and Internal Brace Augmentation in Chronic Ankle Instability, Ankle Sprain and Joint Instability, sponsored by Second Affiliated Hospital, Zhejiang University, School of Medicine. Not yet recruiting at 1 site in China. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-10-16.
Sponsored by Second Affiliated Hospital, Zhejiang University, School of Medicine · Not applicable, Interventional, and Treatment
This is a multicenter, randomized, controlled clinical trial comparing two surgical techniques for the treatment of chronic ankle instability (CAI). CAI is a condition in which the outer ligaments of the ankle remain loose and the ankle continues to give way after repeated sprains, causing pain, swelling, and difficulty with sports and daily activities. About 30-40% of patients who sprain an ankle go on to develop CAI.
All patients in this study receive arthroscopic repair of the anterior talofibular ligament (ATFL) - the main ligament on the outside of the ankle - together with an Internal Brace, a high-strength suture tape that provides immediate mechanical reinforcement. In the experimental group, an absorbable type I collagen scaffold (REGENETEN) is additionally wrapped onto the repair to promote the regrowth of ligament-like tissue. Patients in the control group receive the Internal Brace repair alone.
Eligible patients are aged 18 to 65 with chronic lateral ankle instability that has not improved with standard non-surgical treatment and in whom the ATFL tissue is of poor quality or a previous repair has failed. Participants are randomly assigned 1:1 to one of the two groups, and treatment is assigned by a central computer-generated schedule stratified by study site. Both groups follow the same standardized surgical steps and the same post-operative rehabilitation program.
The main question is whether adding the collagen scaffold leads to better ankle function and stability 12 months after surgery. Patient-reported function, pain, return to sport, MRI evidence of ligament healing, and any complications will be followed for up to 24 months.
Background. Ankle sprain is one of the most common musculoskeletal injuries, accounting for approximately 12% of emergency department visits and 30% of all sports-related injuries. Because the recurrence rate is high, about 30-40% of patients progress to chronic ankle instability (CAI), characterized by recurrent sprains, a subjective feeling of giving way, pain, reduced sports performance, functional limitations, and an increased risk of post-traumatic ankle osteoarthritis.
Arthroscopic ligament repair has become an important surgical option for chronic lateral ankle instability because it can simultaneously address intra-articular pathology such as synovitis, impingement, loose bodies, and osteochondral lesions. However, the strength of a conventional repair may reach only about 50% of the native ATFL, which is often insufficient in patients with scarred, thinned, or partially resorbed ligament remnants, in high-demand patients, or in revision cases.
The Internal Brace technique augments ATFL repair with a high-strength suture tape (FiberTape) anchored to the fibula and talus, providing immediate mechanical stability and protecting the repair during early healing. Its reinforcement is, however, mechanical rather than biological and does not by itself promote the regeneration of ligament-like tissue.
REGENETEN (Smith \& Nephew) is a highly purified, bioinductive, absorbable type I collagen scaffold with a porous microstructure and aligned fiber orientation. It supports host cell migration and tissue ingrowth, gradually degrades over approximately six months, and is gradually replaced by tendon-/ligament-like tissue. A randomized study of 124 patients with non-acute full-thickness rotator cuff tears reported a one-year re-tear rate of 8.3% with REGENETEN augmentation versus 25.8% in controls, and additional studies have shown improvements in pain and function scores.
Objective. To compare the clinical efficacy and safety of arthroscopic ATFL repair with Internal Brace augmentation alone versus Internal Brace augmentation combined with REGENETEN bioaugmentation in patients with chronic lateral ankle instability.
Study design. A prospective, multicenter, randomized, parallel-group, controlled, superiority trial. After written informed consent, eligible patients are randomized 1:1 to one of two groups, with stratification by study site and allocation concealed using a central computer-generated schedule. The study is investigator-initiated. The total study duration is 24 months from the date of ethics approval.
Population. Adults aged 18-65 with clinically and radiologically confirmed chronic lateral ankle instability refractory to standardized non-operative treatment, and with poor ATFL tissue quality (scarring, thinning, partial resorption, intra-operative assessment of insufficient repair tension, high BMI, or high sport demand), or with prior failed lateral ligament repair requiring revision.
Interventions. Both groups undergo standardized arthroscopic ATFL repair with Internal Brace augmentation, using the LassoLoop self-locking suture technique for the residual ligament and bioabsorbable suture anchors plus a 4.75 mm SwiveLock anchor with FiberTape to construct the Internal Brace. In the experimental group, a REGENETEN collagen scaffold braided onto a TigerTape suture is passed through fibular and talar bone tunnels and fixed with 4.75 mm SwiveLock anchors, completing the bioaugmented repair. Post-operative anterior drawer testing is performed under arthroscopy to confirm stability.
Primary endpoint. Change from baseline in the Karlsson-Peterson ankle function score at 12 months post-operatively.
Secondary endpoints (assessed at 3, 6, 12, and 24 months). FAOS subscales (Pain, Symptoms, ADL, Sport/Rec, QoL); FAAM-ADL and FAAM-Sports; Tegner activity score; NRS pain at rest and after activity; anterior drawer and talar tilt tests; MRI evaluation of ATFL continuity, thickness, signal intensity, and (in the experimental group) scaffold integration, absorption, and remodeling; subjective giving-way and fear of re-sprain; recurrent sprain rate; treatment failure and revision surgery rate; and safety (infection, wound healing problems, nerve injury, thromboembolism, joint stiffness, persistent pain, implant-related irritation or foreign-body reaction, and collagen-scaffold-related adverse events).
362 studies on the registry are indexed under Ankle Injuries; 72 are open to participants now.
This study's planned enrollment of 84 is above the median of 60 across 281 interventional studies indexed under Ankle Injuries.
Browse Ankle Injuries studies →Second Affiliated Hospital, Zhejiang University, School of Medicine is the lead sponsor of 90 studies on the registry; 60 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Arthroscopic ATFL repair combined with Internal Brace mechanical augmentation and REGENETEN collagen scaffold bioaugmentation. The REGENETEN scaffold is braided onto a TigerTape suture and fixed through fibular and talar bone tunnels with 4.75 mm SwiveLock anchors.
Procedure: Arthroscopic Anterior Talofibular Ligament Repair · Device: Internal Brace Augmentation · Device: REGENETEN Bioinductive Collagen Scaffold
Arthroscopic ATFL repair combined with Internal Brace mechanical augmentation (FiberTape fixed with bioabsorbable anchors and 4.75 mm SwiveLock anchors) but without REGENETEN bioaugmentation.
Procedure: Arthroscopic Anterior Talofibular Ligament Repair · Device: Internal Brace Augmentation
Arthroscopic examination and repair of the anterior talofibular ligament (ATFL) using the LassoLoop self-locking suture technique via standard anteromedial and anterolateral portals. The residual ligament is debrided and reattached to its anatomic footprint on the fibula.
Mechanical augmentation of the ATFL repair using a FiberTape high-strength suture tape anchored to the fibula with a bioabsorbable suture anchor and to the talus with a 4.75 mm SwiveLock anchor, providing immediate post-operative stability and protecting the repair during early healing. The Internal Brace system is manufactured by Arthrex.
Intervention Description (\*) Biological augmentation using a REGENETEN bioinductive, absorbable type I collagen scaffold (Smith \& Nephew) braided onto a TigerTape suture, passed through fibular and talar bone tunnels, and fixed with 4.75 mm SwiveLock anchors. The scaffold has a porous microstructure and aligned fiber orientation that supports host cell migration and tissue ingrowth, gradually degrades over approximately six months, and is replaced by host tendon-/ligament-like tissue.
Change from Baseline in Karlsson-Peterson Ankle Function Score at 12 Months
The Karlsson-Peterson ankle function score (range 0-100, higher = better) assesses subjective symptoms (30 points), objective clinical findings (30 points), and activity level (40 points). The change from baseline is calculated as the 12-month score minus the pre-operative score. The between-group difference (bioaugmentation vs. mechanical augmentation only) is compared using a superiority framework.
Time frame: 12 months post-operatively
FAOS Subscale Scores
The Foot and Ankle Outcome Score (FAOS) is a 42-item patient-reported questionnaire with five subscales: Pain, Symptoms, Activities of Daily Living, Sport/Recreation, and Quality of Life. Each subscale is scored 0-100 (higher = better). Mean values and changes from baseline are compared between groups.
Time frame: 3, 6, 12, and 24 months post-operatively
FAAM-ADL Score
The Foot and Ankle Ability Measure - Activities of Daily Living (FAAM-ADL) is a 21-item patient-reported outcome measure scored 0-100 (higher = better). The change from baseline is compared between groups.
Time frame: 3, 6, 12, and 24 months post-operatively
FAAM-Sports Score
The Foot and Ankle Ability Measure - Sports (FAAM-Sports) is an 8-item patient-reported outcome measure scored 0-100 (higher = better) that assesses more demanding activities. The change from baseline is compared between groups.
Time frame: 3, 6, 12, and 24 months post-operatively
Tegner Activity Scale Score
The Tegner activity scale is a graduated 0-10 numeric scale (higher = greater activity level). The current activity level and the time to return to pre-injury activity level are recorded.
Time frame: 3, 6, 12, and 24 months post-operatively
NRS Pain Score at Rest and After Activity
The Numeric Rating Scale (NRS) for pain is an 11-point scale ranging from 0 (no pain) to 10 (worst imaginable pain), assessed both at rest and after standardized activity. Mean scores are compared between groups.
Time frame: Each follow-up visit (3, 6, 12, and 24 months post-operatively)
MRI Assessment of ATFL Continuity, Thickness, and Signal Intensity
Magnetic resonance imaging of the operated ankle is performed to evaluate ATFL continuity (continuous, partially disrupted, completely torn), thickness (normal, mildly thickened, markedly thickened, thinned/atrophic), and signal intensity (low, intermediate, high, mixed). In the bioaugmentation group, REGENETEN scaffold integration, absorption, and tissue remodeling are also evaluated.
Time frame: 6, 12, and 24 months post-operatively
Anterior Drawer Test Result
The anterior drawer test is a manual clinical test of ATFL competence. The result is graded as negative, weakly positive, positive, or strongly positive. Distribution of grades is compared between groups.
Time frame: 3, 6, 12, and 24 months post-operatively
Talar Tilt Test Result
The talar tilt test is a manual clinical test of combined ATFL and calcaneofibular ligament competence. The result is graded as negative, weakly positive, positive, or strongly positive, and the talar tilt angle is measured on varus stress radiographs. Distribution of grades and the mean angle are compared between groups.
Time frame: 3, 6, 12, and 24 months post-operatively
Subjective Instability and Recurrent Sprain Rate
Patient-reported subjective giving way, fear of re-sprain, and the incidence of recurrent ankle sprain during follow-up are recorded at each visit. The proportion of patients with each outcome and the recurrent sprain rate are compared between groups.
Time frame: Each follow-up visit through 24 months
Treatment Failure and Revision Surgery Rate
Treatment failure is defined as persistent marked instability, recurrent sprain, imaging evidence of repair failure, or the need for further surgical intervention. The rate of treatment failure and the rate of revision surgery are recorded through 24 months of follow-up.
Time frame: Through 24 months post-operatively
Incidence of Adverse Events and Device-Related Complications
Adverse events (infection, wound healing problems, nerve injury, thromboembolism, joint stiffness, persistent pain, implant-related irritation, foreign-body reaction) and REGENETEN-related adverse events (local inflammation, foreign-body reaction, suboptimal healing) are recorded at each visit. The incidence rate, severity, and device-relationship are documented.
Time frame: Through 24 months post-operatively
Plan to share: No — De-identified individual participant data will not be publicly shared. Access to the de-identified dataset may be considered upon reasonable request to the principal investigator and subject to approval by the local institutional review board.
Start is estimated for Sep 2026; primary completion for Sep 2029, 36 months later.
Of 133 non-industry interventional studies with no phase under Ankle Injuries, half reached primary completion within 9 months of starting (the median), counting those still running; a quarter within 4 and three quarters within 31. This study's planned 36 months is above that.
Counting every sponsor, half of 137 studies reached it within 9 months; a quarter within 4 and three quarters within 31.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Second Affiliated Hospital, Zhejiang University, School of Medicine