Abstract
Background
Arthroscopic Bankart repair is a widely accepted treatment for anterior shoulder instability. The choice between knotted and knotless suture anchors has biomechanical implications, though clinical outcomes remain unclear.
Purpose
This study compares clinical outcomes of knotted versus knotless suture anchors in arthroscopic Bankart repair.
Methods
A retrospective single-centered review of 22 patients undergoing arthroscopic Bankart repair (July 2022 to December 2024) was conducted. Patients were categorized into two equal groups based on knotted or knotless anchor types. The Constant-Murley Shoulder (CMS) score was used as the primary outcome. Secondary outcomes included recurrence and surgical complications.
Results
There was no significant difference in postoperative CMS between knotted and knotless groups (p = 0.058). Both groups showed significant improvements from baseline; no recurrences occurred. One case of wound infection was observed in the knotted group.
Conclusion
Knotted and knotless suture anchors showed comparable clinical outcomes in arthroscopic Bankart repair. Biomechanical advantages of knotless anchors may not necessarily translate into better clinical outcomes. Surgeons may choose anchor type based on preference and case-specific considerations.
Introduction
Bankart lesion, defined as avulsion of the anteroinferior capsulolabral complex from the glenoid rim, was described by Dr Arthur Brudell Sydney Bankart to be present in approximately 90% of recurrent anterior dislocations. 1 With popularization of arthroscopic technology and surgical techniques, the treatment for Bankart lesion has emerged from open to arthroscopic Bankart repair, showing excellent safety profiles and results. One meta-analysis concluded that arthroscopic Bankart repair resulted in 7-fold decrease in recurrence rate compared to conservative management. 2 Arthroscopic Bankart repair was also known to show better improvement in shoulder range of motion, while producing similar complication rates and safety in comparison to open repair. 3
Suture anchors are critical components in an arthroscopic repair and available in knotted and knotless designs. In knotless sutures anchors, a bone hole was predrilled for employment of suture anchor. Using a suture passer, a wire loop was passed through the torn labral tissue, then shuttled back into the inbuilt splice locking mechanism for tightening and tensioning under direct visualization. This omits the need to hand-tie knots outside the portal, before pushing them back into the working field for tightening. With such method, knotless suture anchors allow surgeons to minimize the risk of knot loosening, knot irritation and potentially save operating time in comparison to knotted sutures.
Though knotless anchors may offer theoretically superior biomechanical properties with lower stiffness, less suture slippage, and less soft tissue failure, 4 evidence for better clinical outcomes was limited. The purpose of this study was to investigate whether biomechanical advantage of knotless sutures translates into better patient outcomes, and to evaluate and compare the functional outcomes of both types of suture anchors in an arthroscopic Bankart repair.
Materials and methods
The study was a single-centered retrospective study conducted at the orthopedic unit of a district general hospital between July 2022 and December 2024. Patients with history of anterior shoulder dislocation of traumatic etiology, Bankart lesion visualized on magnetic imaging, and an arthroscopic Bankart repair performed, were included. Patients with additional arthroscopic procedures (such as capsular plication, interval closure) during arthroscopic Bankart repair, coexisting significant shoulder pathologies, revision surgeries, and age below 18 years were excluded. As it is department's usual practice to routinely perform arthroscopic Bankart repair with <10% bone loss based on MRI measurements, patients with >10% glenoid bone loss were excluded in accordance with departmental protocol.
Image workup included standard shoulder radiograph (anteroposterior view and axillary view) and MRI of the shoulder. The Constant-Murley Shoulder (CMS) score were recorded the day before surgery.
All operations were performed by a single team of specialist shoulder surgeons using a standardized shoulder arthroscopy technique with the patient under general anesthesia. Patients were positioned in lateral positions under arm traction. A standard posterior portal was established as viewing portal with two anterior portals established under direct arthroscopic visualization using outside-in technique with the help of a spinal needle to ensure optimal placement of the cannulas. Diagnostic shoulder arthroscopy of the glenohumeral arthroscopy was performed. After identifying and confirming the Bankart lesion, the capsulolabral tissues were released and mobilized from the glenoid rim using periosteal elevator and radiofrequency ablator. The capsuloabral tissues were subsequently brought up to the glenoid neck by Kingfisher Grasper to ensure adequate tension of the subsequent repair. Suture anchors were placed at the glenoid edge with either knotted anchor (Iconix, Stryker) or knotless anchor (FiberTak, Arthrex) with subsequent passage of the sutures through the capsulolabral tissues for Bankart repair. The patients were placed in arm slings with passive pendulum exercises at 2 weeks postoperatively, and active range of exercises at postoperative 6 weeks.
The primary clinical outcome of this study was the CMS score, which was assessed by a questionnaire covering components regarding patient's pain severity, effect on activities of daily living, shoulder range of movement and shoulder strength. Secondary outcomes of this study included surgical complications and morbidities like postoperative infection and recurrent instability.
The patients were followed up at the outpatient clinic at 2 weeks, 8 weeks and 6 months postoperatively. The outcome assessors were blinded from the grouping allocation of the patients. Statistical analysis was performed using SPSS statistical software version 22 (IBM Corp., Armonk, NY, USA). Continuous variables were presented as means with standard deviations if they are normally distributed. Student’s t-test was employed to compare continuous variables that have normal distribution. The preoperative and postoperative CMS scores between and within the two groups were compared using t-test, with p-value of <0.05 considered significant.
Results
A total number of 22 patients were recruited and divided into two groups: group I with arthroscopic Bankart repair performed using knotted anchors and group II using knotless suture anchors. Each group contained 11 patients. As shown in Table 1, patient's demographics with regards to age, number of dislocations, time to surgery, premorbid activity level, operative time, etiology of shoulder dislocation, and size of Bankart lesion reflected as number of suture anchors used, were roughly similar with no significant difference. No patients were lost to follow up within the 6-month postoperative timeframe.
Patient demographics in knotted and knotless groups.
The preoperative and postoperative CMS mean scores in group I (knotted anchors) were 68.1 ± 19.9 and 82.0 ± 10.1, respectively. The preoperative and postoperative CMS mean scores in group II (knotless anchors) were 70.0 ± 17.3 and 74.7 ± 16.9, respectively. Their performance in each component of the CMS score were summarized in Table 2. The results of our study indicated that there was no significant difference in postoperative CMS score between knotted and knotless suture anchors (p = 0.058). Though statistically insignificant in the knotless group, patients in both knotted and knotless suture anchor groups showed improvement in their CMS scores after arthroscopic Bankart repair was performed (see Table 3). Patients performed significantly better in daily function after surgery in group I, and in power after surgery in group II. No recurrences were detected between both groups.
Mean scores of components included in CMS score in groups I and II.
p-Values (t-test) of preoperative and postoperative CMS scores in groups I and II.
In a post hoc comparison of postoperative CMS scores, the knotted group had a higher mean CMS than the knotless group (83.4 vs 76.0; mean difference 7.4 points; 95% CI −6.1 to 20.8; p = 0.26), indicating no statistically significant difference between techniques and considerable imprecision due to the small sample size. A post hoc power calculation (by independent t-test and Cohen's d) indicates 19.6% power to detect the observed difference (α = 0.05, two-tailed), confirming the study is underpowered and emphasizing clinical judgment over statistical significance. Similar findings were observed for improvement in CMS in both groups (mean ΔCMS 9.7 vs 5.9; p = 0.54), again without evidence of a clear advantage for either method.
One patient in the knotted group was found to be complicated with wound infection by coagulase-negative Staphylococcus. Contrast computed tomography postop showed a sinus tract extending from humeral defect draining to skin with suspected osteomyelitic changes at humeral head and anteroinferior glenoid. The patient underwent arthroscopic debridement and was treated with a prolonged 4-week course of intravenous vancomycin. Upon latest follow up, the patient was cured of infection and had no recurrence in shoulder dislocation.
Discussion
The study demonstrated that there was no significant difference in the overall CMS score between knotted and knotless anchor sutures in arthroscopic Bankart repair. This suggested that the short-term functional outcomes between knotted and knotless suture anchors were comparable. Both groups showed better CMS scores after surgery, indicating that arthroscopic Bankart repair was an effective and evidence-based procedure to improve patient's daily function and prevent recurrences in shoulder dislocation.
In the biomechanical study done by Lacheta et al. on cadaveric shoulders, knotless all-suture anchor configuration showed significantly lower strain and fewer instances of suture slippage than the knotted anchor configuration. 4 However, such biomechanical properties were not consistently demonstrated in other types of soft tissue repairs. In another study done by Benca et al. on biomechanical comparison of knotted and knotless suture anchors in acetabular rim, both groups displayed no significant difference in stiffness and ultimate load. 5 Nolte's cadaveric biomechanical study on knotted versus knotless anchors also showed no significant difference in mean load to failure and stiffness. 6 Nonetheless, knotless anchors were thought to provide advantage of avoiding soft tissue and cartilage abrasive knots, possible adhesions, and knot failures due to technical difficulty and knot inconsistency. 7
However, limited evidence demonstrated significance of such biomechanical advantage on clinical outcomes. A retrospective comparative study done by Jae et al. at minimal 2-year follow-up showed that re-dislocation rates and clinical scores were similar in both the knotted and knotless group in an arthroscopic Bankart repair. 8 Another study done by Ng et al. comparing 87 patients with arthroscopic Bankart repair using either knot-tying or knotless sutures showed that although both groups showed statistically significant and similar improvement in VAS and Constant scores, there was no difference in recurrence and re-dislocation rates. 9 Jain's systematic review of 9 studies involving 720 patients comparing knotted and knotless arthroscopic Bankart repair also concluded there was no clear difference in functional outcomes, residual pain, and rate of complications as re-dislocation, subluxation and revision surgery. 10
Hence, the results from our retrospective study aligned with current literature opinion on functional outcomes of knotted and knotless anchors that biomechanical advantage of knotless suture anchors may not necessarily translate into better clinical outcomes. Nonetheless, given its versatility and theoretical advantage, surgeons may opt for knotless sutures based on their own technical experience and tailored to patient's specific requirements. Interestingly, contrary to the common notion that knotless suture anchors may shorten operative time, there was no significant difference in operative time observed between the knotted and knotless anchor groups from this study (p = 0.292). The reason for this could possibly be explained by the steep learning curve required for surgeons to using knotless anchors. It may take time and experience to familiarize with its use before using it as a tool to shorten operative time.
Results from the study were limited by its small sample size being a single-center retrospective study design. A limitation is the lack of standardized glenoid bone loss measurement, which influences recurrence risk in Bankart repair. Future prospective studies should incorporate 3D CT quantification on the percentage of glenoid bone loss in all recruited patients. Patients were followed up only within a short-term period ranging from 3 to 15 months. The wide confidence interval (−6.1 to +20.8) and low post hoc power (19.6%) reflect imprecision due to small sample size, consistent with the study's exploratory nature. The power of study could be improved by increasing number of recruited patients from different centers, and by improving the method design into a prospective cohort study. Further research on the topic may focus on long-term complications, cost-effective analysis, and patient specific factors that might influence choice of anchor type.
It was also interesting to note that there was one case complicated with wound infection in the knotted suture group in contrast to none in the knotless suture group. This suggested it might be beneficial to investigate on whether knotless sutures could lower infection rates perhaps by shortening operation time, or by simplifying surgical technique in an arthroscopic Bankart repair.
Conclusion
Our clinical study suggested that both knotted and knotless anchors deliver comparable short-term functional outcomes in arthroscopic Bankart repair. The type of suture anchors used in arthroscopic Bankart repair should be tailored to surgeon's preference, experience, and patient's specific requirements. Further research on this topic by increasing power and validity of our study, or on other related areas of interest with knotless suture Bankart repairs, would be of great benefit to patients with recurrent shoulder dislocations in the future.
Footnotes
ORCID iDs
Ethical approval and informed consent statements
The retrospective study has been submitted to the Hospital Authority Central Institutional Review Board (Central IRB). All participants included in this retrospective study provided verbal consent for the use of their clinical data for research purposes.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data availability
The data of this article is available and shared.