Clinical outcomes of anterior tibiofibular ligament’s distal fascicle transfer versus ligament reconstruction with InternalBrace™ for chronic ankle instability patients

Chronic ankle instability (CAI) is a common pathological condition secondary to ankle sprains in professional athletes and the general population (1‐5). Between 20 and 40% patients experience CAI ensuing from repeated sprains or inappropriate initial management of acute sprains (6). CAI is caused by functional or mechanical instability of lateral ankle ligaments, and people present with recurrent ankle instability events. The ligaments involved in CAI include the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the posterior talofibular ligament (PTFL) (7, 8). Moreover, intra-articulation lesions are found in 93% of patients who suffer from ankle instability (9). It is recognized that untreated CAI will lead to severe consequences including osteoarthritis, sybaritic and post-traumatic arthritis (10‐14). In the clinic, conservative treatments include pain control, ankle activity restriction and physiotherapy (15). If initial treatments fail, surgical options such as anatomic repair, ligament reconstruction and augmented repair should be considered using either arthroscopy or open surgery (3, 16).

At present, a new method for CAI patients who cannot undergo a direct repair operation is ligament reconstruction. The graft types, fixation materials and methods vary widely in different ligament reconstruction procedures and have been described in previous studies (17‐23). In many operations, InternalBrace™ (Fa. Arthrex, Naples) is used to strengthen the CAI-related ligaments (10). InternalBrace™ reconstruction allows residual ligament tissue to acquire additional strength. Excellent long-outcomes for reconstruction had been proved especially for patients with poor tissue quality or failure of the previous repair operation, and young patients with sports needs (24, 25). Unfortunately, the relative difficulty of the techniques, the significantly high cost of procedures and other complications were noticed by many surgeons. Currently, some researchers propose that the anterior tibiofibular ligament’s (ATiFL) distal fascicle, which also known as Bassett’s ligament (18) can be transferred as a reconstruction technique to treat CAI (22, 26). Some studies (27‐29) have declared that ATiFL’s distal fascicle played an important role in ankle function and could be used as a safer and reliable biological reinforcement for the ATFL repair (26).

There is controversy surrounding which method should be chosen during chronic ankle instability operation. Studies on ATiFL’s distal fascicle transfer are limited. Current studies only focus on the outcomes of anatomic study (26), while clinical outcomes are seldom mentioned. The purpose of this study is to compare the clinical outcomes of ATiFL’s distal fascicle transfer technique and ligament reconstruction with the InternalBrace™ technique in treating CAI patients using the AOFAS score, the VAS score, the anterior drawer test and a patient satisfaction score.

The trial was a single center, retrospective trial with the primary objective to evaluate the hypothesis that ATiFL’s distal fascicle transfer operation (minimally invasive surgery) was not inferior to ligament reconstruction with InternalBrace™. Information was collected from all participants after preoperatively obtaining written informed consent in accordance with the Declaration of Helsinki. At the beginning, 29 traceable patients from all ages in the general population treated in our hospital were enrolled (13 underwent ATiFL’s distal fascicle transfer operation and 16 underwent ligament reconstruction with InternalBraceTM) from October 2019–February 2021. There was no randomization between ATiFL’s distal fascicle transfer and ligament reconstruction surgery groups, and which technique to use was determined by one orthopedic senior surgeon who specializes in treating athletic injuries of ankle with arthroscopic (minimally invasive) procedures. Then, propensity score matching (PSM) was applied to achieve balanced groups at baseline using a logistic regression model. Final covariates were age, sex, preoperative AOFAS scores, preoperative VAS scores and preoperative anterior drawer test scores. The matching ratio is 1:1 with standard caliper width of 0.05. It is was approved by the ethics committee of the First Affiliated Hospital of Jinan University.

From October 2019 through February 2020, a total of 25 patients (14 males and 11 females) were enrolled after PSM (Fig. 4). Among them, 12 patients including 6 women and 6 men underwent ligament reconstruction with InternalBrace™. The remaining 13 patients, including 5 women and 8 men, underwent ATiFL’s distal fascicle transfer reconstruction. After propensity score matching, the two groups were comparable. Patients’ median age at surgery was 33.2 years (range 22–40). The two groups had no significant difference with respect to gender, follow-up duration, preoperative AOFAS score, preoperative VAS score and preoperative anterior drawer test grade. A comparison of baseline characteristics in both groups is displayed in Table 2.

The mean postoperative VAS score on a 0–10 scale was 4.01 ± 1.37 in InternalBrace™ group and 3.31 ± 1.32 in the ATiFL’s distal fascicle transfer group. No substantial differences were seen in the VAS score (P = 0.178, independent-samples t test) (Table 2). The mean patient satisfaction score was 7.27 ± 1.29 and 7.92 ± 1.32 in the InternalBrace™ group and the ATiFL’s distal fascicle transfer group, respectively. No significant differences were found in patient satisfaction score (p = 0.180, independent-samples t test) (Table 3). There was also no significant variation between the two groups considering the anterior drawer test (p = 0.960, independent-samples t test). Overall, there were 8 (66.7%) patients with grade 0 (normal) laxity and 4 (33.34%) patients with grade 1 laxity in the internal brace group. There were 9 (69.23%) patients with grade 0 (normal) laxity, 3 (23.08%) patients with grade 1 laxity and 1 (7.69%) patient with grade 2 laxity in the ATiFL’s distal fascicle transfer group (Table 3).

However, the between-group difference in AOFAS score was significant (p = 0.025, independent-sample t test). The AOFAS score was considered “good” (86.45 ± 4.08) in the InternalBrace™ group and “excellent” (89.85 ± 3.65) in the ATiFL’s distal fascicle group (Table 3).

Two patients engaged in our research suffered from complications. One in the InternalBrace™ group developed superficial infections around the operative region, which were controlled successfully with oral antibiotics. One in the ATiFL’s distal fascicle transfer group was found having sural nerve injury.

The most important contribution of this study is that for the first time, the clinical improvement and functional outcome of ATiFL’s distal fascicle transfer operation was assessed compared with ligament reconstruction surgery with InternalBrace™ in CAI patients in a controlled trial.

Many iterations of repair and reconstruction surgeries were described and evaluated, including the modified Brostrom operation (MBO)(4), arthroscopic modified Brostrom operation with a nonabsorbable InternalBrace™ (27), reconstruction with semitendinosus autografts (35), and anatomical reconstruction of ligament with a gracilis ligament graft (36), Chrisman–Snook operation for reconstruction of lateral ligament (37). Although these previous surgical procedures have demonstrated excellent results, some disadvantages, including donor site morbidity associating with autograft harvesting, significant high cost of procedures and immunogenic response associating with allografts, were reported. Because the relationship between ATiFL’s distal fascicle and ankle anterolateral soft-tissue impingement was proposed by some researchers, the possibility of utilizing this ligament as a biological reinforcement to treat CAI have been put forward in some studies. An anatomical study (26) was previously performed and showed excellent outcomes for anatomical reconstruction. These favorable outcomes were proved by our repeat anatomic study (Fig. 5). It is also noteworthy that the ligament was sutured in the previous anatomical study, which may have caused ligament damage during a real operation. To avoid this limitation, we designed a loop ligature to prevent ligament damage. In our study, clinical outcomes were evaluated and good-to-excellent functional outcomes, pain control and complication control in ATiFL’s distal fascicle transfer group were observed.

In our study, symptomatic patients who used ATiFL’s distal fascicle as a biological reinforcement for an ATFL reconstruction presented statistically significant improvement of AOFAS score from before surgery to final follow-up (ƿ < 0.05). These findings may be supported by the hypothesis that ATiFL’s distal fascicle can retain the ankle’s normal receptor population (26). Some neuroanatomical studies on the ATiFL’s distal fascicle have shown that using this ligament as biological reinforcement has predominance of type IV mechanoreceptors (37, 38), which relate to pain sensation, and type II mechanoreceptors (39), which relate to acceleration or deceleration of the joint.

Paresthesia and neurological complication evaluations were also performed in this study. Overall, both methods showed excellent outcomes in complication rates. Our results also showed no substantial difference in anterior drawer tests after recovery from the operation. Despite the favorable outcomes, we acknowledge that one individual who underwent ATiFL’s distal fascicle transfer operation suffered from grade 2 laxity. As this patient went back to work immediately after the operation, inappropriate postoperative rehabilitation may be closely related to this condition. There was no statistical variation in VAS score between two groups. Overall, the functional and clinical results indicated that using ATiFL’s distal fascicle as reinforcement for the ATFL reconstruction was objectively successful.

In addition, after comparing the satisfaction of patients who underwent ATiFL’s distal fascicle transfer operation with those underwent ligament reconstruction with InternalBrace™ operation, similarly high-degree satisfaction rates were recorded at the final follow-up. Despite these high-degree satisfaction rates from patients, the long operation time was mentioned by some surgeons who performed new technique. During the operation, surgeons spent much time stripping the ligament, which is a new technique that was suggested in 2018, and therefore, surgeons would have a learning curve to master the technique. Overall, considering that occasional pathological change in this ligament was found in the prior study, which may contribute to tibiotalar impingement syndrome, resection of this ligament for lateral ligament reconstruction was considered a valid and reliable method for treating CAI.

The use of ATiFL’s distal fascicle as a biological reinforcement also economical and practical. During ATiFL’s distal fascicle transfer, only one anchor was inserted in the distal part, and no anchor was needed in proximal part. Therefore, the fees of the operation were decreased significantly. Because different patients have different widths and lengths of ATiFL’s distal fascicle, therapeutic methods should be chosen according to individual patients.

It is important to recognize the limitations of this study. First, because it uses a new technique, the minimum follow-up of 12 months and mean follow-up of 14 months are too short to investigate the long-term functional outcome. Good-to-excellent patient-oriented outcome and clinician-oriented outcome with 1-year follow-up were recorded in our study, while longer term cohort studies are needed after patients return to sports. A second limitation of the study that warrants discussion is that a relatively small number of patients were assigned to ATiFL’s distal fascicle transfer operation, and thus, additional multi-center controlled trials are required to corroborate these findings. However, we would such as to report these promising results of our new technique for treating CAI. Based on these results, we firmly believe that chronic ankle instability can be successfully treated when primary repairment is not available. Time should be given for learning and evaluating this technique in further studies.

In conclusion, ATiFL’s distal fascicle transfer operation seems to provide similar complication rates and patient satisfaction rates as ligament reconstruction with the InternalBrace™ operation. Our initial data indicate that the new method has potential to attain good-to-excellent clinical outcomes. At the same time, this new method has been confirmed to be both economical and practical. We believe that this technique may be considered a viable treatment option for chronic lateral ankle instability for both patients and surgeons.