Single anchor versus double anchor for arthroscopic anterior talofibular ligament repair: A systematic review and mate-analysis of cohort studies

Abstract

Purpose

To determine whether a double anchor is more effective than a single anchor in the surgical repair of the anterior talofibular ligament (ATFL) in patients with ankle instability.

Methods

This study searched PubMed, Embase and the Cochrane Library to identify potential studies that compared the clinical outcomes of double anchors and single anchors for ATFL repair from inception to July 31st, 2023. The study aligned with the 2020 Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines and checklist. The Risk of Bias in Nonrandomized Studies-of Interventions (ROBINS-I) tool was used to evaluate methodologic quality and risk of bias. The meta-analysis was performed with random effects. Outcomes, including American Orthopaedic Foot & Ankle Society Score (AOFAS), Karlsson Ankle Functional Score (KAFS), Tegner activity score, return to sport rate, complications and revision surgery events, were recorded.

Results

A total of 845 articles were identified after an initial search of the three databases. Four retrospective studies involving 231 individuals were included for further analysis. There was no significant difference between the single-anchor group and the two-anchor group in terms of the AOFAS (risk ratio, −0.44, [−2.22; 1.34]) or KAFS (mean difference, −2.81, [−6.87; 1.25]). However, in terms of the Tegner activity score and the return to sport rate, the single-anchor group had significantly lower scores and longer times than the double-anchor group. No complications or revision surgery events were reported.

Conclusions

In patients with chronic ankle instability, both single anchors and double anchors can provide good functional outcomes. For patients who participate in physically demanding sports, double anchors may be a superior option.

Level of Evidence

Level Ⅲ, meta-analysis of Level Ⅲ

Keywords

ankle chronic lateral ankle instability one anchor suture anchor surgery sport two anchors

Introduction

Chronic ankle instability (CAI), which is often caused by ankle sprain, is one of the most common sports injuries encountered by foot and ankle surgeons.^1,2 CAI is characterized by repeated sprains, prolonged and persistent pain and ankle subluxation.³ Common risk factors include high BMI, midfoot cavus, hindfoot varus, and generalized laxity neuromuscular stability deficits.^4,5 Although there is a paucity of literature analysing the cost of treating patients with CAI, it is financially burdensome as a common sequela of ankle sprains.^6–8 Methods to treat CAI has become an important topic of discussion.

Effectively treatment for CAI relies on addressing both mechanical and functional instability.⁹ Surgical treatments are often performed when nonoperative treatments are ineffective.^10,11 One of the current surgical procedures is to repair the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL). However, there is no consensus on whether to use a single anchor or double anchor for the ATFL.

A single anchor is a cheaper option, but double anchors theoretically provide more contact area. The clinical efficacy of the two different options deserves further exploration.

The aim of this study was to explore whether double anchors are more effective than single anchors in the surgical repair of the ATFL via a meta-analysis of cohort studies. The hypothesis was that double anchors are not superior to single anchors in ATFL repair in terms of AOFAS, KAFS, Tegner activity score, return to sport rate and complication rate.

Method and materials

Study protocol

The study was registered on PROSPERO (CRD42022328173) and aligned with the 2020 Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines.¹²

Search strategy

Two independent researchers explored three databases, PubMed, Embase and the Cochrane Library, from inception to July 31, 2023. The authors searched the databases with the following terms: ((talofibular ligament) OR (ankle)) AND ((anchor) OR (suture anchor)). Only English studies were included during this process.

Inclusion criteria

Studies were included when they met the following criteria:

• Participants: Patient with CAI and undergoing anterior talofibular ligament repair

• Intervention: Double anchors were used to repair the anterior talofibular ligament during the operation.

• Comparator: A single anchor was used to repair the anterior talofibular ligament during the operation.

• Outcome: American Orthopaedic Foot & Ankle Society Score (AOFAS),¹³ Karlsson Ankle Functional Score (KAFS),¹⁴ Tegner activity score, return to sport rate,¹⁵ complications and revision surgery event.

• Study: Cohort study

Exclusion criteria

The exclusion criteria were as follows:

• Traditional review, systematic review or meta-analysis article

• Cadaver experiment study or cell experiment

• Technical note

• Cross-sectional or case‒control study

Data extraction process

Two independent researchers gathered data from eligible studies. Basic characteristics were collected as follows: author, year, age, country, sex, body mass index (BMI), concomitant injuries, operation method, fixation technique, postoperative management, outcome, and level of evidence (LOE). Additionally, AOFAS, KAFS, Tegner activity score, return to sport rate (a level equal to or higher than preinjury activity), complications (including wound infection, numbness, nerve injury, and vascular injury) and revision surgery events were extracted for further analysis. When there was a disagreement between the two researchers, a third researcher made the final decision.

Data synthesis and statistical analysis

This study focuses on the meta-analysis conducted through R software (version 4.3.1) with a meta package. Heterogeneity of the meta-analysis results was assessed with I² and tau,² and a random-effects model was performed for all analyses. Continuous outcomes were evaluated by mean differences (MDs) with 95% confidence intervals (95% CIs), and dichotomous outcomes were calculated via risk ratios (RRs) with 95% CIs. The diamond represents the final synthetic effect of data from included studies being presented in a forest plot. All outcome comparison analyses were two-tailed, with a significance of 0.05.

Risk of bias evaluation and quality assessment

For cohort studies, the ROBINS-I tool, which included 7 evaluation domains (bias due to confounding, bias in the selection of participants chosen for the study, bias in the classification of interventions, bias due to deviations from the intended interventions, bias due to missing data, bias in the measurement of outcomes and bias in the selection of the result reported), was used to assess the risk of bias.¹⁶

Results

Literature search and selection process

A total of 845 studies (PubMed = 523, Embase = 265, Cochrane = 57) were included after an extensive search of the three databases. A further search identified 215 duplicates, and the remaining 630 studies were screened. After excluding studies on unrelated topics, a total of five studies remained to be searched further. Eventually, 4 studies^17–20 met the inclusion criteria (Figure 1).

Figure 1.

2020 Preferred Reporting Items for Systematic Reviews (PRISMA) flow chart.

Study characteristics

The four studies included were all from China and published from 2019 to 2023, and the inclusion criteria for one of the studies excluded patients with osteochondral injuries of the talus (Table 1). Moreover, the diameter of the anchors in the four retrospective studies ranged from 2.9 to 3.5 mm. In addition, in one study, different methods were used for measuring the duration of fixation in postoperative rehabilitation management for patients with or without talus cartilage injuries (Table 2).

Table 1.

Characteristics and details of the included studies.

Author	Year	Country	Age (years)	Sex	BMI (kg/m²)	Concomitant injuries	Follow-up time (months)
Li, H. et al¹⁷	2019	China	SA: 34 ± 10	SA: 11 M 9F	SA: 24 ± 3	SA:7 OCD 5 STS	SA: 37 ± 10
Li, H. et al¹⁷	2019	China	DA: 31 ± 6	DA: 23 M 8F	DA: 24 ± 2	DA: 10 OCD 9 STS	DA: 40 ± 5
Feng, S. M. et al¹⁸	2020	China	SA: 32.3 ± 8.4	SA: 22 M 14F	SA: 25.1 ± 2.7	SA:11 OCD 7 STS	SA: 44.0 ± 9.2
Feng, S. M. et al¹⁸	2020	China	DA: 30.9 ± 10.0	DA: 27 M 12F	DA:24.8 ± 2.2	DA: 14 OCD 11 STS	DA: 43.7 ± 8.7
Zhou, Y. F. et al¹⁹	2021	China	SA:29.13 ± 5.65	SA: 12 M 10F	SA:22.49 ± 3.35	SA:11 OCD 7 STS	SA:30.27 ± 4.09
Zhou, Y. F. et al¹⁹	2021	China	DA:28.67 ± 7.88	DA: 15 M 9F	DA:23.44 ± 3.55	DA: 14 OCD 11 STS	DA:33.08 ± 5.57
Feng, S. M. et al²⁰	2023	China	SA:34.2 ± 8.8	SA: 20 M 12F	SA:24.8 ± 2.4	NA*	SA:30.27 ± 4.09
Feng, S. M. et al²⁰	2023	China	DA:35.4 ± 7.9	DA: 19 M 8F	DA:24.4 ± 3.2	NA*	DA:33.08 ± 5.57

Abbreviations: BMI: body mass index; F: female; DA: double anchor; M: male; NA: not available; OCD: osteochondral defect; SA: single anchor; STS: sinus tarsi syndrome.

*This study excluded patients with osteochondral lesions of the talus.

Table 2.

Operation details.

Author	Operation method	Fixation technique	Postoperative management	Outcome	LOE
Li, H. et al¹⁷	Arthroscopy	SA: The suture anchor (2.9-mm Loopine [DePuy Mitek, Raynham, MA]) was placed in the middle point of the fibular ATFL footprint with two sutures. DA: The first suture anchor (2.9-mm Loopine [DePuy Mitek, Raynham, MA]) was placed approximately 1 cm superior to the distal tip of the fibula with one suture, and the second anchor (2.9-mm Loopine [DePuy Mitek, Raynham, MA]) was placed into the fibula superiorly and level with the lateral shoulder of the talus with one suture	Isometric contraction started from the second day. Immobilization was achieved with a short leg cast, which was then changed to an ankle brace after 2 weeks of passive range of motion. Weight bearing was encouraged after 2 weeks	AOFAS, KAFS, return to sport rate, Tegner activity score, complication, revision surgery event	3
Feng, S. M. et al¹⁸	Arthroscopy	SA: The site of anchor (Fastin RC 3.5 mm, Smith & Nephew, Andover, MA) insertion was the midpoint of the footprint area. DA: The first anchor (Fastin RC 3.5 mm, Smith & Nephew, Andover, MA) was fixed at 1.0 cm from the proximal end of the fibula tip, and the second anchor was fixed at the proximal end of the fibula in the footprint area	Fixed with a short leg brace and weightless floor and isometric exercises were started on the second day. Two weeks after the procedure, patients with a talar cartilage lesion and microfracture maintained brace fixation for 6 weeks. Other patients were allowed to remove the brace after 4 weeks. Then, they were fitted with boots and started strength exercise. After 8 weeks, they were instructed to progressively perform exercise involving ankle varus and plantarflexion. At 12 weeks after the operation, patients were allowed to gradually resume normal physical activity	AOFAS, KAFS, return to sport rate,complication, revision surgery event	3
Zhou, Y. F. et al¹⁹	Arthroscopy	SA: One suture anchor was placed at the midpoint of the ATFL footprint. DA: The first anchor was loaded with 1 suture (3.0 mm, SutureTak; Arthrex) and placed at the distal insertion of the ATFL on the fibula. The second anchor was then placed superiorly at the proximal insertion on the fibula	Isometric contraction started from the second day. Fixed with a short cast for 2 weeks and then replaced by a short leg brace. Patients were allowed partial weight-bearing with a brace for 4 weeks. At 6 weeks postoperatively, patients started progressive weight bearing, and full weightbearing gait was permitted without a brace	AOFAS, KAFS, return to sport rate, Tegner activity score,complication, revision surgery event	3
Feng, S. M. et al²⁰	Arthroscopy	SA: At the midportion of the anterior talofibular ligament footprint region, a double-load suture anchor (Fastin RC 3.5 mm, Smith & Nephew, Andover, MA) was inserted. DA: After the anterior talofibular ligament footprint region on the fibula had been freshened, the first double-loaded suture anchor (Fastin RC 3.5 mm, Smith & Nephew, Andover, MA) was inserted into the proximal portion of the footprint region and the second double loaded suture anchor (Fastin RC 3.5 mm, Smith & Nephew, Andover, MA) was inserted into the distal portion of the footprint region	Two weeks of immobilization in a short leg brace with non-weight-bearing functional exercises and isometric exercise. A boot was used for the next 4 weeks, with progressive weightbearing for the first 2 weeks and fully weight-bearing functional exercises started thereafter. At 6 postoperatively, patients were allowed to gradually resume normal physical activity	AOFAS, KAFS, return to sport rate,revision surgery event	3

Abbreviations: ADT: Anterior drawer test; AOFAS: American Orthopaedic Foot & Ankle Society Score; FAOS: Foot and Ankle Outcome Score; KAFS: Karlsson Ankle Functional Score.

Risk of bias evaluation and quality assessment

Three studies^17–19 were considered to have a moderate risk of bias in terms of the selection of participants for the study due to the inclusion of patients with concomitant injuries. One study¹⁸ was considered to have a high-risk of bias in terms of the measurement of outcomes due to differences in patient immobilization time during rehabilitation, which may have an effect on postoperative outcome assessment. (Table 3).

Meta-analysis

AOFAS

Four studies^17–20 involving 231 individuals reported AOFASs, and the results were not significantly different between the single-anchor group and the double-anchor group (RR, −0.44, [-2.22; 1.34]). The heterogeneity was high (I² = 7%; τ² = 0.988, p = .36). (Figure 2)

Figure 2.

Forest plot showing the difference in the American Orthopaedic Foot & Ankle Society Scores between the single-anchor and double-anchor groups. CI, confidence intervals; MD, mean difference; SD, standard deviation.

KAFS

Four studies^17–20 involving 231 individuals reported KAFSs, and the results were not significantly different between the single-anchor group and the double-anchor group (MD, −2.81, [-6.87; 1.25]). The heterogeneity was high (I² = 76%; τ² = 11.878, p < .01). (Figure 3).

Figure 3.

Forest plot showing the difference in Karlsson Ankle Functional Score between the single-anchor and double-anchor groups. CI, confidence intervals; MD, mean difference; SD, standard deviation.

Tegner activity score

Two studies^17,19 involving 97 individuals reported Tegner activity scores, and the results showed that the single-anchor group had a lower Tegner activity score than the double-anchor group (MD, −0.87, [-1.30; −0.45]). There was no heterogeneity (I² = 0%; τ² = 0, p = .49). (Figure 4).

Figure 4.

Forest plot showing the difference in the Tegner activity scores between the single-anchor and double-anchor groups. CI, confidence intervals; RR, risk ratio.

Return to sport rate

Four studies^17–20 involving 231 individuals reported the return to sport rate, and the results showed that the single-anchor group had a lower proportion of patients who were able to return to sports than the double-anchor group (RR, 0.60, [0.40; 0.92]). Heterogeneity was not high (I² = 66%; τ² = 0.107, p = .03). (Figure 5)

Figure 5.

Forest plot showing the difference in the return to sport rate between the single-anchor and double-anchor groups. CI, confidence intervals; RR, risk ratio.

Complication

A total of 3 studies^17–19 involving 172 individuals reported complications, and none of the patients experienced postoperative complications.

Revision surgery event

A total of 4 studies^17–20 involving 231 individuals reported revision surgery data, and no patient requested a second surgery.

Table 3.

Quality assessment of bias using the risk of bias in nonrandomized studies (ROBINS-I) tool.

Author	Bias due to confounding	Bias in selection of participants into the study	Bias in classification of interventions	Bias due to deviations from intended interventions	Bias due to missing data	Bias in measurement of outcomes	Bias in selection of the reported result	Overall bias
Li, H. et al¹⁷	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Feng, S. M. et al¹⁸	Low	Moderate	Low	Low	Low	High	Low	High
Zhou, Y. F. et al¹⁹	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Feng, S. M. et al²⁰	Low	Low	Low	Low	Low	Low	Low	Low

Discussion

The main findings of this study are that the efficacy of the single-anchor is not inferior to that of the double-anchor.

The AOFAS for pain, function and voluntary movement, stability, and foot force lines provide a more comprehensive assessment of daily function in patients after ATFL repair. At the same time, the KAFS is an assessment of pain, swelling, stiffness, and other aspects of daily activities. There was no significant difference between the single-anchor group and the double-anchor group in terms of these two outcome measures, which indicates that both surgical methods are suitable for meeting the daily life needs of the patient. There were no reported complications or secondary surgical events, demonstrating the safety of both procedures. In an insertional Achilles tendon surgery study, DeVries, J. G et al.²¹ reported a noticeable difference in cost between single anchor repair (US$391.18 ± US$272.10) and double row repair (US$1811.2 9 ± US$169.47). Therefore, for most patients, satisfactory results can be achieved regardless of the type of surgery performed.

The Tegner activity score is more reflective of work and physical activity. In this study, the return to sport rate represents the number of people who return to preinjury or higher levels of sport. The results show that 2 anchors perform better in meeting the demands of higher intensity sports. Cottom JM et al.²² also showed that when the number of proximal suture anchors was increased, there was a statistically significant increase in strength with respect to maximum failure loads. In addition, theoretically, 2 anchors can provide a larger contact area in the footprint area, which facilitates the patient's postoperative recovery. Therefore, 2 anchors are a more appropriate choice for patients who participate in high-intensity exercise.

Implications for practice

For patients

For patients who participate in low-intensity exercise, a single anchor can be sufficient for daily life and is cost-effective.

For clinicians

A single anchor improves the clinical prognosis of patients who participate in low-intensity exercise and is cost-effective.

For patients who exercise intensely, especially athletes, double anchors facilitate the return to their respective sport.

Limitations

There are three major shortcomings of this study. First, the small number of eligible studies and smaller sample sizes undoubtedly affect the reliability of the outcome effects. The second point is that the type of fixator used during surgery varied among operators and there were inconsistencies in the postoperative rehabilitation programs, all of which may have had some impact on the final results. In addition, all the included studies were retrospective, which contributes to the low level of evidence.

Conclusions

Footnotes

Author contributions

DYF conceived the design of the study. DYF and LXH collected the data, performed the data analysis and contributed to the design of the study. DYF analysed the data. DYF and LZ prepared and revised the manuscript. The authors read and approved the final content of the manuscript.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Ding Yuan Fan

Data Availability Statement

The present study was a review of the previously published literature.

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