Monocortical fixation of the coracoid in the Latarjet procedure is significantly weaker than bicortical fixation

Sutures, Screws, Buttons, and Anchors: A Review of Current Bone Graft Fixation Devices for Glenoid Bone Loss in the Unstable Shoulder

PURPOSE OF REVIEW

Anterior shoulder instability is associated with concomitant injury to several stabilizing structures of the shoulder, including glenoid bone loss. While instability is most common in young athletes and patients with predisposing conditions of hyperlaxity, recurrent shoulder instability can occur throughout various age ranges and may lead to longer term effects including pain and shoulder arthritis. Glenoid bone loss exceeding certain thresholds is generally treated by glenoid reconstruction via bone block augmentation to adequately stabilize the glenohumeral joint. These procedures increase the width of the articular surface on which the humeral head can translate before dislocation and, based on the procedure performed, provide a sling effect via the conjoined tendon, and increase tension to support the anterior capsule. The purpose of this review is to summarize the available literature regarding bone block fixation techniques.

RECENT DEVELOPMENTS

Various fixation techniques have been utilized to secure bone block transfers. Though screw fixation has traditionally been used for bone block fixation, suture buttons, suture anchors, and all-suture techniques have been utilized in attempts to avoid complications associated with the use of screws. Biomechanical studies report variable force-resistance, displacement, and mode of failure when comparing screw to suture button-based fixation of glenoid bone blocks. Clinical and radiographic studies have shown these novel suture-based techniques to be comparable, and in some cases advantageous, to traditional screw fixation techniques. While screw fixation has long been the standard of care in glenoid bone block procedures, it is associated with high complication rates, leading surgeons to endeavor toward new fixation techniques. In available biomechanical studies, screw fixation has consistently demonstrated high maximal load-to-failure and displacement with cyclic loading. Studies have reported similar clinical and radiographic outcomes in both screw and suture-based fixation methods, with evidence of reduced bone resorption with suture fixation. While suture button fixation is associated with a higher rate of recurrent instability, overall complication rates are low. Future research should address biomechanical shortcomings of suture-based fixation techniques and continue to assess long-term follow-up of patients treated with each fixation method.

Inlay structure can improve bone graft stability in the Bristow procedure

BACKGROUND

Compared with the Latarjet procedure, the Bristow procedure has a lower screw-related complication rate but poor bone healing. A modified Inlay Bristow procedure has been reported to significantly improve the bone healing rate, but the biomechanical mechanism is unclear. The aim of this study was to evaluate the biomechanical stability of the bone graft between a modified Inlay Bristow procedure and the classic Bristow procedure.

METHODS

Sixteen left scapula models (Sawbones, Composite Scapula, and fourth generation) were randomly divided into 2 groups (8:8). The bone graft in the first group was fixed with a 3.5 mm screw using the Inlay structure. The bone graft in the second group was fixed with a 3.5 mm screw via the traditional method. The maximum cyclic displacement, ultimate failure load and stiffness were evaluated biomechanically. The failure type was recorded for each model.

RESULTS

Cyclic loading tests demonstrated that the maximum cyclic displacement of the Inlay procedure was significantly smaller (P = .001) than that of the classic procedure. The Inlay Bristow technique resulted in a significantly higher (P = .024) ultimate failure load than the classic Bristow technique. The stiffness of the classic group was 19.17 ± 4.01 N/mm and that of the inlay group was 22.34 ± 5.35 N/mm (P = .232). Failure was mainly due to bone graft fractures through the drill hole or glenoid bone fractures.

CONCLUSION

Inlay Bristow fixation of the bone graft in a Sawbones model provides significantly stronger fixation and better time point zero stability than classic Bristow fixation, suggesting a higher likelihood of graft union.

Recurrent Instability after the Latarjet Procedure

The Latarjet procedure is a favored approach for managing chronic and recurrent dislocation, especially in the presence of bone loss. Although generally yielding excellent results, the procedure carries a 15 to 30% complication rate. Although recurrent instability is a major concern, various complications such as infection, nerve injuries, and hardware impingement can also necessitate revision after a Latarjet procedure. Strategies for addressing this issue include glenoid bone grafting, using autogenous bone grafts from the iliac crest or distal clavicle, and allografts, with fresh lateral distal tibial allografts offering advantages because of their osteochondral nature. In addition, soft-tissue procedures offer another solution for recurrent instability, suitable for patients lacking substantial bone loss or those experiencing multidirectional instability. This review aims to provide a comprehensive overview of the causes and management strategies for recurrent instability following a failed Latarjet procedure.

A Systematic Review of Screw and Suture Button Glenoid Augmentation Constructs

Background

Glenohumeral dislocations often lead to glenoid bone loss and recurrent instability, warranting bony augmentation. While numerous biomechanical studies have investigated fixation methods to secure a graft to the glenoid, a review of available constructs has yet to be performed.

Purpose

To synthesize the literature and compare the biomechanics of screw and suture button constructs for anterior glenoid bony augmentation.

Study Design

Systematic review.

Methods

A systematic review was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. There were 2 independent reviewers who performed a literature search using the PubMed, Embase, and Google Scholar databases of studies published between 1950 and 2020. Studies were included that compared the biomechanical outcomes of fixation for the treatment of anterior shoulder instability with glenoid bone loss.

Results

Overall, 13 of the 363 studies screened met the inclusion criteria. The included studies measured the biomechanical strength of screws or suture buttons on a cadaveric or synthetic Latarjet construct. Screws and suture buttons were biomechanically similar, as both constructs exhibited comparable loads at failure and final displacement. Screw type (diameter, threading, or composition) did not significantly affect construct strength, and double-screw fixation was superior to single-screw fixation. Additionally, 2 screws augmented with a small plate had a higher load at failure than screws that were not augmented. Unicortical double-screw fixation was inferior to bicortical double-screw fixation, although construct strength did not significantly decrease if 1 of these screws was unicortical. Further, 2 screws inserted at 15° off axis experienced significantly higher graft displacement and lower ultimate failure loads than those inserted at 0° parallel to the glenoid.

Conclusion

Suture buttons provided comparable strength to screws and offer an effective alternative to reduce screw-related complications. Augmentation with a small plate may clinically enhance construct strength and decrease complications through the dispersion of force loads over a greater surface area. Differences in screw type did not appear to alter construct strength, provided that screws were placed parallel to the articular surface and were bicortical.

FIXATION METHODS IN LATARJET: BIOMECHANICAL COMPARISON OF SCREW TYPES AND PLATE FIXATION

Objective

Latarjet procedure is often preferred in recurrent shoulder dislocations accompanied by glenoid bone loss. It is observed that the superiority of bone graft fixation methods is still controversial. The aim of this study is to biomechanically compare the bone graft fixation methods in the Latarjet procedure.

Methods

15 third-generation scapula bone models were divided into 3 groups. Graft was fixated in the first group with fully-threaded cortical screws of 3.5mm diameter, in the second group two 16 mm partially-threaded cannulated screws of 4.5mm diameter, and in the third group via a mini plate and screw. The hemispherical humeral head was placed on the tip of the cyclic charge device, and thus, the charge applied to the coracoid graft was homogeneous.

Results

No statistically significant difference was found between paired comparisons (p>0.05). The forces in 5 mm displacement in total vary between 502-857N. Total stiffness measurements ranged between 105 and 625; the mean value was 258.13±53.54 with no statistically significant difference by groups (p = 0.958).

Conclusion

This biomechanical study showed that there is no difference between three coracoid fixation options in terms of fixation strength. Unlike previous assumptions, plate fixation is not biomechanically superior to screw fixation. Surgeons should consider their personal preferences and experience in choosing fixation methods.

What is the best position for coracoid fixation in the Latarjet procedure?

Hypothesis

Multiple problems and complications associated with Latarjet fixation have been described; thus, this is the first study in the literature to identify the maximum allowed screw clamping force and best fixation screw position for Latarjet surgery.

Methods

A variation of distal and proximal coracoid screw positions with and without a flat washer was evaluated through finite element analysis, at a minimum distance of 3 mm from the edge. A loading progression test was performed until the maximum stress reached a limit imposed by the bone yield. We identified the maximum allowed screw clamping force based on a von Mises and maximum principal stresses failure theory.

Results

When using the flat washer, the cortical bone generally has only space for 1 piece. For this reason, as a primary study, it was observed that when the distal screw was more than 7 mm from the edge, the clamping force supported will be higher than that during the proximal fixation regardless of the proximal location screw. We have found that the best position is 7 mm from the distal edge, with the highest compression of 445 N (7 mm proximal distance, 5 mm distal distance) in due respect to the von Mises failure theory. To get around this lack of space situation, in this study, we have proposed a fixation plate to replace the flat washer. This plate has shown very interesting values when compared to the previously flat washer study, but now, for both screw holes. With those results, we can assure that using a fixation plate like this will ensure surgery safety and higher allowed compression force when clamping the bolts.

Conclusion

The distal screw provided higher tensile strength values when located more than 7 mm from the coracoid edge. The geometry of the coracoid in its distal position supports higher stress loads than in the proximal position. When the flat washer was in the proximal position, the coracoid was submitted with a more distributed and uniform load, preventing localized bone damage as a crush.

Factors affecting biomechanical strength of Latarjet constructs: A systematic review and meta-regression

BACKGROUND

The Latarjet procedure reduces recurrent glenohumeral instability but has potential hardware and graft complications. The procedure has been modified to use various screw types as well as suture buttons. Biomechanical studies have evaluated the effect of these implants on construct strength. With varying results it is unclear whether there is an optimal implant to use.

METHODS

We conducted a systematic review of human cadaveric biomechanical studies evaluating Latarjet ultimate failure load. Two independent reviewers screened articles and included them after full text review. Additional factors including implants used, graft orientation, cortices engaged, drill diameter, and screw characteristics were recorded. Meta-regression was performed on the 145 specimens from eight studies that met inclusion criteria.

RESULTS

Screw fixation resulted in a 396.8 N (95% CI, 149.8-643.7) N higher ultimate failure load against shear stresses than suture buttons (p = 0.002). There were no differences between implants for ultimate failure load against tensile forces. Tensile strength was significantly affected by drill diameter with each millimeter of increase reducing the mean ultimate failure load by 127.4 N (95% CI, 41.2-213.6) N (p = 0.004).

CONCLUSIONS

These results suggest that using screw fixation and minimizing drill diameter can obtain the maximum ultimate failure load against both shear and tensile forces in a Latarjet construct.

A biomechanical comparison of steel screws versus PLLA and magnesium screws for the Latarjet procedure

INTRODUCTION

The fixation of the coracoid process onto the glenoid is an important step of the Latarjet procedure, and implant-associated complications are a relevant and severe problem. This study compares the fixation strength and failure mode of two biodegradable materials with stainless-steel screws.

METHODS

24 Fresh-frozen cadaveric scapulae were divided into three groups of equal size and received a coracoid transfer. Cadavers were matched according to their bone mineral density (BMD). In group 1, small-fragment screws made of stainless steel were used. In the second group, magnesium screws were used, and in the third group, screws consisted of polylactic acid (PLLA). A continuously increasing sinusoidal cyclic compression force was applied until failure occurred, which was defined as graft displacement relative to its initial position of more than 5 mm.

RESULTS

At 5-mm displacement, the axial force values showed a mean of 374 ± 92 N (range 219-479 N) in group 1 (steel). The force values in group 2 (magnesium) had a mean of 299 ± 57 N (range 190-357 N). In group 3 (PLLA), failure occurred at 231 ± 83 N (range 109-355 N). The difference between group 1 (steel) and group 2 (magnesium) was not statistically significant (P = 0.212), while the difference between group 1 (steel) and group 3 (PLLA) was significant (P = 0.005).

CONCLUSION

Stainless-Steel screws showed the highest stability. However, all three screw types showed axial force values of more than 200 N. Stainless steel screws and PLLA screws showed screw cut-out as the most common failure mode, while magnesium screws showed screw breakage in the majority of cases.

EVIDENCE

Controlled laboratory study.

No difference in 90-day complication rate following open versus arthroscopic Latarjet procedure

The purpose of this study was to compare the 90-day complication rate between the open and arthroscopic Latarjet procedure. A retrospective review of patients who underwent an open or arthroscopic Latarjet procedure at NYU Langone Health between 2012 and 2019 was performed. The complications, readmissions, and reoperations within 90 days were assessed. Outcomes were compared between the two approaches, and a p value of < 0.05 was considered to be statistically significant. The study included 150 patients (open: 110; arthroscopic: 40), with no patients lost to follow-up within the first 90 days. Both cohorts were similar in terms of patient demographics. No intra-operative complications were observed in either group. Overall, there were 4 post-operative complications with the open approach and 2 with the arthroscopic approach (3.6% and 5.0%, respectively; n.s.) during the study period. Three patients required a readmission within the 90-day period; one patient in both groups required a revision Latarjet for graft fracture, and one patient in the open Latarjet required irrigation and debridement for deep infection (n.s.). With the open approach, there were 2 (2.3%) wound complications, 1 graft complication, and 1 (1.1%) nerve injury. With the arthroscopic approach, there was 1 (2.8%) wound complication and 1 (2.8%) hardware complication. The safety, and 90-day complication and readmission profile of arthroscopic Latarjet is similar to open Latarjet procedure. LEVEL OF EVIDENCE: Level III.

Evaluating the effects of arthroscopic Bankart repair and open Latarjet shoulder stabilisation procedures on shoulder joint neuromechanics and function: a single-centre, parallel-arm trial protocol

Introduction

Shoulder instability injuries are common in sports involving collisions and overhead movements. Arthroscopic Bankart repair and the open Latarjet are two commonly used surgical stabilisation procedures. There is a lack of knowledge surrounding movement strategies, joint loading and muscle strength after each of these procedures. This study will compare: (1) shoulder joint neuromechanics during activities of daily living and an overhead sporting task; (2) shoulder range of motion; (3) shoulder strength; and (4) self-reported shoulder function and health status, between individuals who have undergone an arthroscopic Bankart repair versus open Latarjet.

Methods and analysis

This is a prospective cohort, single-centre, non-randomised parallel arm study of surgical interventions for athletic shoulder instability injuries. Thirty participants will be recruited. Of these, 20 will have experienced one or more traumatic shoulder instability injuries requiring surgical stabilisation—and will undergo an arthroscopic Bankart repair or open Latarjet procedure. The remaining 10 participants will have no history of shoulder instability injury and act as controls. Participants will undergo baseline testing and be followed up at 3, 6 and 12 months. A two-way (group×time) analysis of variance with repeated measures on one factor (ie, time) will compare each outcome measure between groups across time points.

Ethics and dissemination

This study was approved by the Barwon Health and Deakin University Human Research Ethics Committees. Outcomes will be disseminated through publications in peer-reviewed journals and presentations at relevant scientific conferences.

Trial registration number

Australian and New Zealand Clinical Trials Registry (ACTRN12620000016932).

Arthroscopic Latarjet Stabilization: Analysis of the Learning Curve in the First 90 Primary Cases: Early Clinical Results and Computed Tomography Evaluation

PURPOSE

To assess the learning curve of arthroscopic Latarjet, evaluating time of surgery, clinical outcomes, complications, revisions, and recurrence.

METHODS

Arthroscopic Latarjet procedures performed from 2011 to 2016 were reviewed. Satisfaction rate, subjective shoulder value, Walch-Duplay, Rowe scores, range of motion, and stability were evaluated on clinical examination. Graft position and fusion were analyzed using computed tomography. All patients were divided into 3 chronological groups.

RESULTS

Ninety patients (3 groups of 30) were available for clinical evaluation (96,8%). The mean follow-up was 23.7 months. Surgical time was significantly (P = .0028) longer in group I (mean 128 minutes, standard deviation [SD] 33.6) when compared with groups II (mean 102 minutes, SD 16.2) and III (mean 108 minutes, SD 21.8). A regression analysis and cumulative sum learning curve analysis showed the surgeon oscillated around mean operative time (112.7 minutes; SD 27.2) after 30 procedures. The number of intraoperative complications was significantly greater (P = .024) in Group I (5 cases; 17%) compared with zero in group II, and 3 (10%) in group III. All 3 cases (3.3%) of recurrence were reported in group I (P = .033). Significantly, 2 of 3 patients with recurrence had intraoperative graft complications (P = .0107). Overall patient satisfaction was evaluated as 92%, SSV 90%, Walch-Duplay and Rowe scores, respectively, 79 and 81 points. Nine revisions (10%) were reported. No significant differences were found between the results and revisions of the 3 chronological groups.

CONCLUSIONS

This study confirms that the arthroscopic Latarjet procedure provides good clinical and radiologic results at short-term follow-up. The surgical time, frequency of complications, and number of hardware problems significantly decreased after the first 30 cases. As such, surgeons should be aware of the elevated potential for complications and recurrence early in the learning curve-serious intraoperative complications are important risk factors for recurrence.

LEVEL OF EVIDENCE

III. Therapeutic study: case-control study.

Biomechanical evaluation of suture buttons versus cortical screws in the Latarjet-Bristow procedure: a fresh-frozen cadavers study

INTRODUCTION

A commonly used method of fixation of the transferred coracoid in the traditional Latarjet-Bristow procedure (open or arthroscopic) is by two bicortical screws. Although mechanically effective, screw fixation is also a major source of hardware and neurologic complications. This study aimed to compare the biomechanical performances of traditional metal screws and endobuttons as fixators of the Latarjet-Bristow procedure.

MATERIALS AND METHODS

Nine fresh-frozen cadaveric human scapulae with the conjoined tendon attached to the coracoid process were used for the Latarjet-Bristow procedure. The specimens were randomly assigned one of two groups: fixation using two 4.5-mm cannulated partially threaded Latarjet-Bristow experience screws or fixation using a suture-button construct. Specimens were secured in a material testing machine and cyclically preconditioned from 2 to 10 N at 0.1 Hz for ten cycles. They were then pulled to failure at a normalized displacement rate of 400% of the measured gauge length per minute. The maximal load-to-failure, stiffness and stress were calculated using a custom script. The failure mechanism and site were recorded for each specimen.

RESULTS

There were no significant differences in the maximal load-to-failure or other biomechanical properties of the two fixation techniques, but the failure mechanisms were unique to each one. Four specimens fixated with screws underwent graft failures (fracture) through the proximal or distal drill hole. Five specimens fixated with endobuttons underwent failure due to glenoid bone fractures.

CONCLUSIONS

A single endobutton fixation appears to be biomechanically comparable to screw fixation in the Latarjet-Bristow procedure and provides a lower risk for graft fracture. Further studies with more numerous specimens are warranted to conclusively validate these findings.

Intraoperative graft-related complications are a risk factor for recurrence in arthroscopic Latarjet stabilisation

PURPOSE

The goal of this study was to evaluate clinical and radiological outcomes after arthroscopic Latarjet stabilisation in anterior shoulder instability.

METHODS

Ninety-three patients after primary arthroscopic Latarjet stabilisation were reviewed. Satisfaction, subjective shoulder value (SSV), Walch-Duplay and Rowe scores, and range of motion and stability were evaluated on clinical examination. Computed tomography (CT) was used to analyse graft position and fusion.

RESULTS

Ninety patients (96.8%) were available for clinical and 85 for CT evaluation. The mean follow-up was 23.7 months (13-50, SD 7.1) and age at surgery was 26.2 years (16-44, SD 5.6). Intraoperative complications were reported in eight patients (8.9%) and recurrence in three (3.3%). Significantly, two out of three patients with recurrence had intraoperative graft complications (p = 0.0107). Forty-one patients (45.6%) reported the feeling of "subjective return to sport anxiety". External rotation with arm at the side was 59° (10-90°, SD 20) with 15° (0-70°, SD 17) of loss of rotation. These two factors correlated with results the most. Patient satisfaction was evaluated as 92% (40-100, SD 14) and SSV 90% (30-100, SD12). Revision rate after primary surgery was 10%. CT showed graft healing in 81 (95.3%) patients. A graft position between 2 and 5 o'clock was found in 70 (83.4%) patients and flush to the anterior glenoid rim in 34 (40.5%). Osteolysis of the superior part of the graft was found in 55 (64.7%) patients. CT evaluation showed no correlation with clinical results.

CONCLUSION

Arthroscopic Latarjet stabilisation demonstrates satisfactory results in short-term follow-up; however, intraoperative graft-related complications are a risk factor for recurrence. "Subjective return to sport anxiety" and loss of external rotation with the arm at the side are factors worsening the results. Graft position imperfections and osteolysis of the superior part of the graft reported in CT evaluation do not influence the clinical results.