Do the traditional and modified latarjet techniques produce equivalent reconstruction stability and strength?

Congruent Concavity Restoration of the Reconstructed Glenoid After the Latarjet Procedure: Compensation for the Position of the Graft

BACKGROUND

Few clinical studies have addressed concavity restoration by natural remodeling after a Latarjet procedure. This study investigated the fibrous tissue and osseous remodeling of the reconstructed glenoid and concavity restoration after a Latarjet procedure using postoperative computed tomographic arthrography (CTA).

METHODS

This retrospective study included 31 patients who underwent immediate postoperative computed tomographic (CT) scanning followed by CTA at 6 months postoperatively. We investigated whether fibrous tissue was newly created over the graft, whether the created fibrous tissue restored the congruity of the articular surface and the osseous remodeling of the graft to the glenoid level (whether the osseous portion of the graft was remodeled flush to the glenoid level) and the concavity of the glenoid using the radius of a best-fit circle on the articular surface, and the relationship between the amount of created fibrous tissue and the position of the graft.

RESULTS

In all patients, the fibrous tissue on the graft yielded a smooth articular surface, as revealed by the CTA. The mean radius of the entire glenoid, including the transferred graft, was significantly smaller (p = 0.010) at 33.2 ± 8.5 mm than that of the glenoid posterior to the osseous step-off at 37.6 ± 9.4 mm, which is presumed to be the glenoid before the surgical procedure. Despite the congruity of the articular surfaces due to fibrous tissue seen in the CTA, 14 (45%) of 31 patients showed a subchondral osseous step-off on either the medial side or the lateral side in the immediate postoperative CT scans. However, through osseous remodeling, 8 of the 10 grafts with a lateral step-off and 2 of the 4 grafts with a medial step-off converted to a flush position. The position of the step-off was correlated with the thickness of the fibrous tissue, with a tendency for thicker tissue in cases of a step-off on the medial side (p = 0.014).

CONCLUSIONS

Fibrous tissue formation plus remodeling of the transferred graft resulted in the restoration of a congruent concavity after a Latarjet procedure by compensating for initially non-flush positioning of the graft. However, due to the small sample size in our study, clinical outcomes could not be correlated with radiographic findings, and our recommendation is to continue placing the graft as anatomically as possible.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Simulated Weightbearing and Articular Injury From Transarticular Screws in a Ligamentous Lisfranc Injury Model

BACKGROUND

Transarticular screw fixation is a common surgical treatment for tarsometatarsal ligamentous (Lisfranc) injuries. Iatrogenic damage to articular cartilage from screw placement, however, has been thought to potentially lead to increased risk of tarsometatarsal (TMT) joint arthritis after initial injury. To date, no study has evaluated the effect of weightbearing on articular cartilage after screw fixation. The aim of this study was to create a Lisfranc injury and quantify and compare articular damage due to screw fixation before and after simulated weightbearing.

METHODS

A ligamentous Lisfranc injury was created in 10 cadaveric specimens and treated with transarticular screws. Specimens were cycled for 1000 cycles at 250 N to simulate 2 weeks of physiologic weightbearing. Rotation and diastasis across the Lisfranc complex were measured. Articular injury as a percentage of total articular surface was measured using digital imaging of the first and second TMT joint before and after simulated weightbearing. Comparisons between articular damage were made and statistical analysis was performed.

RESULTS

Simulated partial weightbearing increased articular injury 1.44-fold (P < .001). The second metatarsal (M2) showed the greatest increase (1.54-fold, P = .0047), whereas the first (M1) showed the least (1.35-fold, P = .0083). Increases seen at the medial (1.43-fold, P = .0387) and middle cuneiform (1.44-fold, P = .0292) were intermediate between the values seen at M2 and M1.

CONCLUSION

Articular damage from transarticular screw fixation significantly increased after simulated partial weightbearing. This may increase the risk of arthritis and future morbidity when using transarticular screws for the treatment of ligamentous Lisfranc injuries.

CLINICAL RELEVANCE

Iatrogenic damage to articular cartilage due to screw fixation of ligamentous Lisfranc injuries may be increased with weightbearing.

Primary Stability and Bone Contact Loading Evaluation of Suture and Screw based Coracoid Graft Fixation for Anterior Glenoid Bone Loss

BACKGROUND

Reconstruction techniques for anterior glenoid bone loss have seen a trend from screws to suture-based fixations. However, comparative biomechanical data, including primary fixation and glenoid-graft contact pressure mapping, are limited.

HYPOTHESIS

Suture-based bone block cerclage (BBC) and suspensory suture button (SB) techniques provide similar primary fixation and cyclic stability to double-screw fixation but with higher contact loading at the bony interface.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 60 cadaveric scapulae were prepared to simulate anterior glenoid bone loss with coracoid autograft reconstruction. Graft fixation was performed with 3 different techniques: (1) an interconnected all-suture BBC, (2) 2 SB suspensions, and (3) 2 screws. Initial compression was analyzed during primary fixation. Cyclic peak loading with 50 N and 100 N over 250 cycles at 1 Hz was performed with a constant valley load of 25 N. Optical recording and pressure foils allowed for spatial bone block tracking and contact pressure mapping at the glenoid-graft interface. Load-to-failure testing was performed at a rate of 1.5 mm/s with ultimate load and stiffness measured.

RESULTS

Initial graft compression was higher with screw fixation (141 ± 5 N) compared with suture-based fixations (P < .001), with BBC fixation providing significantly higher compression than SB fixation (116 ± 7 N vs. 91 ± 5 N; P < .001). Spatial bone block migration and ultimate failure load were similar between the BBC and screw groups. The SB group showed significantly increased bone block translation (3.1 ± 1.0 mm; P≤ .014) and rotation (2.5°± 1.4°; P≤ .025) and significantly lower ultimate failure load (180 ± 53 N) compared with the BBC (P = .046) and screw (P = .002) groups. Both suture-based fixations provided significantly increased graft-glenoid contact loading with higher pressure amplitudes (P≤ .032) and contact pressure after cyclic loading (+13%; SB: P = .007; BBC: P = .004) compared with screw fixation.

CONCLUSION

Both SB and interconnected cerclage fixation improved dynamic contact loading compared with screw fixation in a biomechanical glenoid bone loss model. Cerclage fixation was biomechanically comparable with screw fixation but with a greater variability. SB fixation showed significantly lower primary fixation strength and greater bone block rotation and migration.

CLINICAL RELEVANCE

Suture-based bone block fixations improved graft-glenoid contact loading, but the overall clinical consequence on healing remains unclear.

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.

Functional biomechanical comparison of Latarjet vs. distal tibial osteochondral allograft for anterior glenoid defect reconstruction

INTRODUCTION

Glenoid reconstruction is indicated for recurrent glenohumeral instability with significant glenoid bone deficiency. Coracoid autograft (Latarjet) and distal tibial osteochondral allograft (DTA) reconstructions have been used to successfully restore glenohumeral stability. Relative advantages and disadvantages associated with each reconstruction technique have been described. However, direct comparisons of functional glenohumeral biomechanics associated with Latarjet vs. DTA reconstruction are lacking. This study was designed to compare these 2 glenoid reconstruction techniques with respect to joint kinematics and cartilage pressure mapping using a robotic testing system.

METHODS

In accordance with institutional review board policies, human cadaveric shoulders (n = 8) were cyclically tested in the neutral position and 90° of external rotation with 60° and 90° of abduction under a 45-N joint-compression load to measure clinically relevant translations, loads, and torques. Joint contact pressure maps were obtained under a 120-N joint-compression load using pressure mapping sensors. After confirming that a 25% anterior glenoid defect resulted in glenohumeral dislocation, testing was performed to compare 3 conditions: native intact glenoid, 25% anterior glenoid defect with Latarjet reconstruction, and 25% anterior glenoid defect with DTA reconstruction. Analyses of variance and t tests were used to analyze data with statistical significance set at P < .05.

RESULTS

Significant differences in anterior translation, inferior drawer, anterior drawer, compression loads, horizontal abduction, negative elevation (adduction), and external rotation torques during cyclical testing in 90° of external rotation with 60° and/or 90° of abduction were noted when comparing the 2 different glenoid bone reconstruction techniques to native, intact shoulders. The only significant difference between Latarjet and DTA reconstructions for measured translations, loads, and torques was a significantly higher absolute maximum compressive load for Latarjet compared to DTA at 60° of abduction.

CONCLUSION

Latarjet coracoid osseous autograft and distal tibial osteochondral allograft reconstructions of large (25%) glenoid bone defects prevent failure (dislocation) and are associated with significant glenohumeral kinematic differences that largely confer less translation, load, and torque on the joint in abduction when compared to the native state. These findings suggest that these 2 surgical techniques exhibit similar glenohumeral kinematics such that each provides adequate functional stability following anterior glenoid bone reconstruction. Joint compression load and articular contact pressure distribution may favor distal tibial osteochondral allograft reconstruction for treatment of large (25%) anterior glenoid bone defects associated with shoulder instability.

Comparison of the biomechanical stability of transverse and oblique screw trajectories in retrograde intramedullary nailing of supracondylar femur fractures

BACKGROUND

The goal was to determine the effect of addition of oblique trajectory distal interlock screws to a retrograde intramedullary femoral nail on implant stability (stiffness), cycles to failure and mode of failure. The hypothesis was that addition of oblique screws would increase implant stability and number of loading cycles to failure.

METHODS

Eight matched pairs were tested; one femur implanted with a femoral nail with only transverse distal interlock screws and the other with transverse and oblique interlock screws. Axial compressive load was applied to the femoral head and the gluteal tendon was tensioned vertically to simulate standing or at 45° to the sagittal plane to simulate stair climbing. Loads were cycled to increasing amplitude until failure of fixation (10 mm displacement or 10° rotation).

FINDINGS

In simulated standing, oblique screw specimen had greater sagittal bending (bowing) than transverse only specimen. Transverse (axial) plane motion was higher in simulated stair climbing in oblique screw specimen. Oblique screw specimen had higher sagittal plane translation at 600 N of load. At 300 N, oblique screw specimen had lower internal-external rotation than transverse only specimen. A larger number of cycles to failure were observed in four oblique screw of seven paired specimen. Failure (10 mm or 10 degrees of motion) was only achieved during simulated stair climbing.

INTERPRETATION

Our hypothesis that adding oblique screws improves fixation was rejected. Activities of daily living other than standing may constitute a challenge to fracture fixation; fixation failure occurred at lower loads in simulated stair climbing than standing.

Morphometric and Biomechanical Comparison of the Scapular Spine and Coracoid Graft in Anterior Shoulder Instability

BACKGROUND

The scapular spine has been described as a relatively new bone graft alternative used in glenoid augmentation. The classic Latarjet procedure, which transfers the coracoid as a graft, is regarded as the gold standard. The comparison of these 2 techniques has not been fully reported.

PURPOSE

To compare the anatomic and biomechanical properties of glenoid augmentation using scapular spine graft or coracoid graft.

STUDY DESIGN

Controlled laboratory study.

METHODS

The study used 20 fresh-frozen human cadaveric shoulders. A 25% anterior glenoid defect was created, and the specimens were divided randomly to receive glenoid augmentation by scapular spine or coracoid grafts. For both procedures, the grafts were secured to the glenoid defect with 2 screws. Morphometric data, including the glenoid articular area, amount of restoration, and graft dimensions, were obtained. A biomechanical test was conducted in a direct-loading scenario. The construct stiffness, cyclic displacement, and ultimate failure of each specimen were collected.

RESULTS

No significant difference was found in glenoid articular restoration between the scapular spine group and the coracoid group (31% vs 33%, respectively; P = .311). Morphometric analysis indicated that coracoid grafts exhibited significantly greater thickness and height than scapular spine grafts. In biomechanical results, the scapular spine group exhibited significantly greater construct stiffness than the coracoid group (206.3 ± 58.8 vs 148.3 ± 76.0 N/mm, respectively; P = .023). The average failure load in the scapular spine group was not significantly higher than that in the coracoid group. No significant differences in cyclic displacement were found between the 2 techniques.

CONCLUSION

In a simulated 25% anterior glenoid bony defect, a scapular spine graft was comparable with the classic Latarjet procedure in restoring the glenoid articular dimension and exhibited superior construct stiffness in a cadaveric model.

CLINICAL RELEVANCE

The scapular spine may serve as an alternative graft choice in glenoid augmentation surgery considering the amount of articular restoration and initial fixation stability.

Navigation-Guided Trans-glenoid Flexible Fixation Technique for Arthroscopic Autologous Iliac Crest Grafting Treatment of Recurrent Shoulder Dislocation

Recurrent anterior shoulder dislocations accompanied by severe glenoid bone defects are typically treated with arthroscopy. Until now, autologous iliac grafting has been reported with excellent results, and different techniques of bone fixation have been introduced by numerous scholars. In this article, we introduce a specially designed guide that can achieve accurate positioning of the bone graft and a nonrigid graft fixation technique with a single EndoButton (Smith & Nephew). Using this technique, we greatly simplify the arthroscopic procedure and avoid the use of screws.

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.

Biomechanical comparison between various screw fixation angles for Latarjet procedure: a cadaveric biomechanical study

BACKGROUND

The Latarjet procedure is a reliable treatment for the management of anterior glenohumeral instability with glenoid bone loss. However, the biomechanical properties of different fixation angles between screw and glenoid surface (α angle) have rarely been studied. The aim of the study was to investigate and compare the fixation stability, failure load, and failure mechanism between different α angles for Latarjet procedures, which were performed on cadaver specimens.

METHODS

Twenty-four shoulder specimens (8 in each of 3 groups) were dissected free of all soft tissue, and a 25% glenoid defect was created. The coracoid process was osteomized and fixed with 2 screws at 3 different α angles: 0° (group A), 15° (group B), and 30° (group C). Specimens were mounted to a testing apparatus, and cyclic loading (100 cycles at 1 Hz) was applied with a staircase protocol (50, 100, 150, and 200 N). Gross graft displacement and interface displacement were measured. The ultimate failure loads and failure mechanisms were recorded.

RESULTS

There was no significant difference in gross displacement under any cyclic load between 3 groups. However, a significant larger interface displacement was noted in group C than in group A in 150-N cyclic loading (P = .017). Under failure strength testing, all 24 specimens failed because of screw cutout from the glenoid, and the ultimate failure load was similar among the three groups.

CONCLUSION

Compared with the 0° α angle, the displacement after cyclic loading did not significantly increase when the α angle was increased to 15° but significantly increased at 30° for Latarjet procedures, which were performed on cadaver specimens. The results suggest that surgeons should apply the screws as parallel as possible to the glenoid surface when performing the Latarjet procedure. Although mild deviation may not reduce fixation stability, α angles greater than 30° should be avoided.

Comparison of two coracoid process transfer techniques on stress shielding using three-dimensional finite-element model

Background

We created patient-based 3D finite-element (FE) models that simulate the congruent-arc Latarjet (CAL) and traditional Latarjet (TL) procedures and then compared their stress distribution patterns with different arm positions and glenoid defects.

Methods

The computed tomography data of 10 adult patients (9 men and 1 woman, ages: 18–50 years) were used to develop the 3D FE glenohumeral joint models. Twenty-five and 35% bony defects were created on the anterior glenoid rim, and the coracoid process was transferred flush with the glenoid by the traditional and congruent-arc techniques using two half-threaded screws. A load was applied to the greater tuberosity toward the center of the glenoid, and a tensile force (20 N) was applied to the coracoid tip along the direction of the conjoint tendon. The distribution patterns of the von Mises stress in the traditional and congruent-arc Latarjet techniques were compared.

Results

The mean von Mises on the graft was significantly greater for the TL technique than for the CAL. While the von Mises stress was greater in the distal medial part of the graft in the TL models, a higher stress concentration was observed in the distal lateral edge of the coracoid graft in the CAL models. The proximal medial part of the graft exhibited significantly lower von Mises stress than the distal medial part when compared according to technique, defect size, and arm position. Increasing the glenoid defect from 25 to 35% resulted in a significant increase in stress on the lateral side of the graft in both models.

Conclusion

The stress distribution patterns and stress magnitude of the coracoid grafts differed according to the procedure. Due to placing less stress on the proximal–medial part of the graft, the CAL technique may lead to insufficient stimulation for bone formation at the graft–glenoid interface, resulting in a higher incidence of graft osteolysis.

Clinical relevance The CAL technique may lead to a higher incidence of graft osteolysis.

Level of evidence

Basic Science Study; Computer Modeling.

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.

Biceps Brachii Alterations Following the Latarjet Procedure: A Prospective Multicenter Study

Purpose: To prospectively investigate the postoperative forearm supination and elbow flexion strength of both upper extremities and popeye deformity in patients who underwent a mini-open Latarjet procedure for anterior shoulder instability. Methods: Patients who underwent a mini-open Latarjet procedure at two specialized shoulder centers were prospectively evaluated preoperatively (T0) and at least 6 months (T1) after surgery. Subjects were tested for elbow flexion and forearm supination strength of both upper extremities using an isometric dynamometer and customized torque dynamometer. Clinical outcome was assessed by the Constant Score (CS), American Shoulder and Elbow Score (ASES) and Simple Shoulder test (SST). Popeye deformity was defined as a distalization of the greatest circumference of the biceps muscle belly towards the lateral epicondyle of the elbow. Results: A total of 20 patients with a mean age of 27 ± 6 years were included in the study. At a mean follow-up of 10 ± 3 months, the elbow flexion strength was restored to the preoperative state (p = 0.240). Forearm supination strength significantly decreased at final follow-up, to 88 % in the surgical arm (p = 0.015) vs. 90 % in the non-surgical arm (p = 0.023). There was no statistical difference when comparing both arms concerning elbow flexion strength (p = 0.510) and forearm supination strength (p = 0.495). No significant popeye deformity was observed in both arms (p = 0.111 vs. p = 0.508). Clinical outcome scores improved significantly from 73 ± 18 to 82 ± 13 (p = 0.014) for CS and 76 ± 22 to 89 ± 12 (p = 0.008) for ASES score preoperatively to final follow-up. No difference in the SST was documented (p = 0.10). Conclusion: The Latarjet procedure showed to preserve elbow flexion strength and provided comparable forearm supination strength compared to the uninjured arm with reliable clinical outcome in this study population. However, a decrease of forearm supination strength in both arms was persistent at a mean of 10 months postoperatively. No popeye deformity was noted in the postoperative examinations. Level of evidence: Case series, Level III.

Clinical Outcomes of the Traditional Latarjet Versus the Congruent Arc Modification for the Treatment of Recurrent Anterior Shoulder Instability: A Meta-analysis

Background:

Few studies have compared clinical outcomes between the traditional Latarjet procedure for anterior shoulder instability and the congruent arc modification to the Latarjet procedure.

Purpose:

To systematically evaluate the literature for the incidence of recurrent instability, clinical outcomes, radiographic findings, and complications for the traditional Latarjet procedure and the congruent arc modification and to compare results of each search.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review and meta-analysis was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We included studies published between January 1990 and October 2020 that described clinical outcomes of the traditional Latarjet and the congruent arc modification with a follow-up range of 2 to 10 years. The difference in surgical technique was analyzed using a chi-square test for categorical variables, while continuous variables were evaluated using a Student t test.

Results:

In total, 26 studies met the inclusion criteria: 20 studies describing the traditional Latarjet procedure in 1412 shoulders, and 6 studies describing the congruent arc modification in 289 shoulders. No difference between procedures was found regarding patient age at surgery, follow-up time, Rowe or postoperative visual analog scores, early or late complications, return-to-sport timing, or incidence of improper graft placement or graft fracture. A significantly greater proportion of male patients underwent glenoid augmentation using the congruent arc modification versus traditional Latarjet (P < .001). When comparing outcomes, the traditional Latarjet procedure demonstrated a lower incidence of fibrous union or nonunion (P = .047) and broken, loose, or improperly placed screws (P < .001), and the congruent arc modification demonstrated improved outcomes with regard to overall return to sport (P < .001), return to sport at the same level (P < .001), incidence of subluxation (P = .003) or positive apprehension (P = .002), and revision surgery for recurrent instability (P = .027).

Conclusion:

Outcomes after the congruent arc modification proved at least equivalent to the traditional Latarjet procedure in terms of recurrent instability and return to sport, although early and late complications were equivalent. The congruent arc procedure may be an acceptable alternative to traditional Latarjet for the treatment of anterior shoulder instability with glenoid bone loss; however, long-term outcomes of this procedure are needed.

Intra-articular biomechanical environment following modified Bristow and Latarjet procedures in shoulders with large glenoid defects: relationship with postoperative complications

BACKGROUND

Although coracoid transfers including the modified Bristow and Latarjet procedures are widely used to treat anterior shoulder instability, the influence of the choice of procedure on the biomechanical outcomes is not well characterized. We aimed to clarify the intra-articular stress distribution following these 2 procedures using 3-dimensional finite-element analysis and to investigate the role of stress distribution in the pathophysiology of postoperative complications.

METHODS

Overall, 6 male patients aged 17-47 years with unilateral anterior shoulder instability were recruited. Computed tomographic digital imaging and communications in medicine (CT-DICOM) data of the contralateral (healthy) shoulder of each patient was obtained and used for developing the 3-dimensional normal glenohumeral joint model. A 25% bony defect was created in the anterior glenoid rim where the coracoid process was transferred in the standing and lying-down positions to create the Bristow and Latarjet models, respectively. The arm position was set as 0° or 90° abduction. The Young moduli of the humerus and scapula were calculated using CT data, and set as 35.0 MPa and 113.8 GPa for the articular cartilage and inserted screw, respectively. A compressive load (50 N) was applied to the greater tuberosity toward the center of the glenoid, and a tensile load (20 N) was applied to the tip of the coracoid in the direction of conjoint tendon. Elastic analysis was used to determine the equivalent stress distribution.

RESULTS

A significant reduction in mean equivalent stress was observed within the glenoid cartilage for both models (P = .031); however, a new stress concentration appeared within the grafted coracoid-facing region of the humeral-head cartilage in both models. The proximal half of the coracoid graft exhibited lower equivalent stress than the distal half in 5 of the 6 Latarjet models, whereas the proximal half showed higher equivalent stress than the distal half in all 6 Bristow models. High stress concentration was identified at the midpoint of the inserted screw in Bristow models.

DISCUSSION AND CONCLUSIONS

Intra-articular stress distribution may explain the different rates of postoperative complications associated with the modified Bristow and Latarjet procedures. New stress concentration within the humeral-head cartilage might contribute to the development of glenohumeral osteoarthritis following both procedures. Stress shielding in the proximal part of the coracoid graft might contribute to osteolysis following the Latarjet procedure. Surgeons should be aware of the risk of breakage of the inserted screw following the modified Bristow procedure.

Computed Tomography-Based Preoperative Planning Provides a Pathology and Morphology-Specific Approach to Glenohumeral Instability With Bone Loss

PURPOSE

To use computed tomography (CT) to determine a reproducible method of coracoid measurement to compare the ability of the classic Latarjet technique and the congruent arc modification (CAM) to restore native glenoid diameter and to develop a preoperative planning algorithm for glenoid restoration with a goal of achieving an on-track shoulder.

METHODS

Coracoid dimensions were measured on multiplanar reconstructed shoulder CT scans of patients aged 18 to 45 years obtained between December 1, 2019, and March 13, 2020. Patients were excluded if CT demonstrated osteophyte formation, glenoid dysplasia, coracoid fracture, or tumor. The proportion of glenoid diameter able to be restored using classic Latarjet technique and CAM were calculated. A treatment algorithm was proposed considering the amount of bone loss present and coracoid dimensions.

RESULTS

Coracoid dimensions of 117 consecutive patients were measured and varied considerably (length: 17.5-31.8 mm, width: 9.1-20.5 mm, thickness: 6.1-15.7 mm). While most patients had harvestable coracoid length ≥20 mm (male: 96.3% vs female: 94.4%, P = .65), only 27.8% of female patients had coracoid thickness ≥10 mm. When comparing Latarjet techniques, there was no difference in the proportion of patients in whom 30% glenoid diameter could be fully restored, but CAM was able to restore at least 35% in more male and female patients (98.8% vs 79.0% and 100% vs 61.1%, respectively, P = .00001). Intra- and inter-rater reliability was excellent ( intraclass correlation coefficient ≥0.950 for all dimensions).

CONCLUSIONS

We describe a reliable method of measuring coracoid dimensions for preoperative planning of glenoid restoration. The classic Latarjet technique reliably restores the glenoid anteroposterior diameter with bone loss of up to 30%. The majority of female patients have coracoid thickness <10 mm, which may increase the risk of graft fracture when using CAM. The decision to use the classic Latarjet technique or CAM considers each individual's glenoid and coracoid dimensions with a goal of achieving an on-track shoulder.

CLINICAL RELEVANCE

Our reliable method of coracoid measurement demonstrated the differing abilities of the classic Latarjet and CAM to restore the native glenoid diameter. An evidence-based algorithm using these measurements was developed to assist in preoperative planning for glenohumeral instability in the setting of bone loss, with a goal of achieving an on-track shoulder. Alternative techniques may be considered if an on-track shoulder cannot be achieved with Latarjet.

Traditional versus congruent-arc Latarjet anatomic and biomechanical perspective

The congruent-arc Latarjet (CAL) allows reconstruction of a greater percentage of glenoid bone deficit because the inferior surface of the coracoid is wider than the lateral edge of the coracoid used with the traditional Latarjet (TL).

Biomechanical studies have shown higher initial fixation strength between the graft and the glenoid with the TL.

In the TL, the undersurface of the coracoid, which is wider than the medial edge used with the CAL, remains in contact with the anterior edge of the glenoid, increasing the contact surface between both bones and thus facilitating bone consolidation.

The shorter bone distance around the screw with the CAL is potentially less tolerant of screw-positioning error compared to the TL. Moreover, the wall of the screw tunnel is potentially more likely to fracture with the CAL due to the minimal space between the screw and the graft wall.

CAL may be very difficult to perform in patients with very small coracoids such as small women or skeletally immature patients.

Radius of curvature of the inferior face of the coracoid graft (used with the CAL) is similar to that of the native glenoid. This may potentially decrease contact pressure across the glenohumeral joint, avoiding degenerative changes in the long term.

Cite this article: EFORT Open Rev 2021;6:280-287. DOI: 10.1302/2058-5241.6.200074

Distal clavicle autograft for anterior-inferior glenoid augmentation: A comparative cadaveric anatomic study

INTRODUCTION

The aim of this study was to anatomically compare distal clavicle and coracoid autografts and their potential to augment anterior-inferior glenoid bone loss.

METHODS

Ten millimeters of distal clavicle and 20 mm of coracoid were harvested bilaterally from 32 cadavers. Length, weight, and height were measured and surface area and density were calculated. For each graft, ipsilateral measurements were compared and the ability to restore corresponding glenoid bone loss was calculated.

RESULTS

Distal clavicle grafts were larger than coracoid grafts with respect to length (22.3 mm versus 17.7 mm; p < 0.001), height (12.49 mm versus 9.65 mm; p < 0.001), mass (2.72 g versus 2.45 g; p = 0.0437), and volume (2.36 cm³ versus 1.96 cm³; p = 0.002). Coracoid grafts had larger widths (14.56 mm versus 10.52 mm; p < 0.001) and greater density (1.24 g/cm³ versus 1.18 g/cm³; p < 0.001). Distal clavicle surface area was greater on both the articular (2.93 cm² versus 1.5 cm²; p < 0.001) and superior surfaces (2.76 cm² versus 1.5 cm²; p < 0.001) when compared to lateral coracoid surface area.

DISCUSSION

Distal clavicle grafts were larger and restored larger bony defects but had greater variability and lower density than coracoid grafts. Clinical studies are needed to compare these graft options.

Proximal-medial part in the coracoid graft demonstrates the most evident stress shielding following the Latarjet procedure: a simulation study using the 3-dimensional finite element method

BACKGROUND

Although the osteolysis of the coracoid graft is frequently observed after the Latarjet procedure particularly in its proximal part, its pathomechanism is not well understood.

METHODS

Three-dimensional finite element glenohumeral joint models were developed using CT-DICOM data of 10 normal shoulders. A 25% bony defect was created on the anterior glenoid rim, and the coracoid process was transferred flush with the glenoid cartilage using 2 half-threaded screws. In the hanging arm as well as in the 90° abducted positions, a compressive load (50 N) was applied to the greater tuberosity toward the center of the glenoid and a tensile force (20 N) was applied to the coracoid tip along the direction of the conjoint tendon. Next, elastic analysis was performed, and the distribution patterns of the equivalent stress as well as the maximum principal stress were compared among 4 parts (proximal/distal and medial/lateral) of the coracoid graft.

RESULTS

Both the equivalent stress and the maximum principal stress were reduced in the proximal half of the coracoid graft. A high stress concentration was observed in the lateral aspect of the coracoid graft particularly in the 90° abducted position. The proximal-medial part demonstrated the lowest equivalent stress as well as the maximum principal stress for both arm positions, which were significantly lower than those in the distal 2 parts.

CONCLUSION

In the Latarjet procedure, the proximal-medial part of the coracoid graft demonstrated the most evident stress shielding, which may play an important role in postoperative osteolysis.

A cadaveric morphometric analysis of coracoid process with reference to the Latarjet procedure using the "congruent arc technique"

INTRODUCTION

Congruent arc Latarjet procedure involves rotating the coracoid process so that its inferior surface is flush with the glenoid face, owing to their matching radius of curvature (ROC). However, there has been no cadaveric study to actually measure and compare the ROC of coracoid with glenoid, especially in Indian population.

MATERIALS AND METHODS

44 shoulders were dissected in 24 cadavers to measure usable length of coracoid process, width, height, ROC of coracoid and glenoid as well as ulnar length (as proxy of cadaver height). Critical coracoid height and length were estimated based on screw sizes of 2.7 mm, 3.5 mm, 4 mm and 4.5 mm, and pair concordance between height and length calculated. ROC of coracoid and glenoid were compared to measure extent of congruency.

RESULTS

The mean usable length of coracoid process, width and height at mid-point were 21.8 mm, 13.7 mm and 8.6 mm, respectively. Out of the different screw sizes, 2.7 mm screws were found safe in 82% shoulders. 24 coracoid-glenoid pairs fulfilled the operational definition (≤ 5 mm) of congruency while rest 20 were seemingly incongruent chiefly due to coracoid variations, with mean ROC difference 4.13 mm (95% CI 1.51-6.74 mm). The ulnar length was significantly smaller in the incongruent ROC group (p = 0.0002).

CONCLUSIONS

The available length as well as height of the transferred coracoid must be considered when deciding optimum diameter fixation screws in Latarjet procedure. Owing to smaller anatomic dimensions of coracoid in Indian population, 2.7-mm screws provide the safest fixation option. Also, the ROC of coracoid and glenoid does not match in substantial proportion of the cadavers. Pre-operative planning should include a CT-based assessment of glenoid and coracoid dimensions to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.

Similar Results in Return to Sports, Recurrences, and Healing Rates Between the Classic and Congruent-Arc Latarjet for Athletes With Recurrent Glenohumeral Instability and a Failed Stabilization

PURPOSE

To compare the return-to-sport rate, functional outcomes, and complications of the "classic Latarjet" surgery with those of the "congruent arc Latarjet" surgery in athletes with recurrent glenohumeral instability and failed previous stabilization procedures.

METHODS

All the included patients were operated between May 2009 and April 2017. The inclusion criteria were athletes with recurrent anterior glenohumeral instability, a glenoid bone defect greater than 20%, at least 1 previous failed stabilization surgery operated with the classic or the congruent-arc Latarjet procedures, and a minimum 2 years of follow-up. Return to sports, range of motion (ROM), the Rowe score, a visual analog scale for pain, and the Athletic Shoulder Outcome Scoring System score were used to assess functional outcomes. Complications were also evaluated.

RESULTS

A total of 135 athletes were included in the study (55 patients were operated with the classic technique and 80 with the congruent arc technique). The mean follow-up was 40.3 months (range, 24-88 months) and the mean age was 26.5 years (range, 18-45 years). Overall, 87% were able to return to sports and 92% returned at the same level. No significant difference regarding return to sports was found between the groups. No significant difference in shoulder ROM was found between preoperative and postoperative results. The Rowe, visual analog scale, and Athletic Shoulder Outcome Scoring System scores showed statistical improvement after operation (P < .001). No significant difference in shoulder ROM and functional scores was found between patients operated with the classic and congruent arc procedures. There were 6 recurrences (4%). There was no significant difference in the recurrence rate between groups. The bone block healed in 92% of the cases.

CONCLUSIONS

In athletes with recurrent anterior glenohumeral instability and a failed previous operative repair, the Latarjet procedure produced excellent functional outcomes and most athletes returned to sport at their preinjury level with a very low rate of recurrences, regardless of whether the Latarjet was performed with the classic or with the congruent arc technique.

LEVEL OF EVIDENCE

Retrospective comparative study; Level of evidence, 3.

Editorial Commentary: Classic and Congruent-Arc Latarjet Techniques Are Equally Safe and Effective Procedures, so Choose Whichever Technique Works Best in Your Hands for Your Patients

The classic and congruent-arc Latarjet techniques are equally safe and effective in restoring glenohumeral stability, even when performed as a revision of a failed stabilization. The classic technique provides a broader contact area for healing and facilitates and improves screw fixation. The congruent-arc technique theoretically optimizes glenohumeral contact forces because of the matched radius of curvature, provides better restoration of glenoid depth, and restores larger glenoid defects. However, rotating the coracoid graft for the congruent-arc technique eliminates the possibility of imbricating the coracoacromial ligament stump to the capsule. Surgeons have little reason to change from one technique to the other; both techniques result in successful outcomes.

Are the Classic and the Congruent Arc Latarjet Procedures Equally Effective for the Treatment of Recurrent Shoulder Instability in Athletes?

BACKGROUND

There is a lack of evidence in the literature comparing outcomes between the classic and the congruent arc Latarjet procedures in athletes.

PURPOSE

To compare return to sports, functional outcomes, and complications between the classic and the congruent arc Latarjet procedures in athletes with recurrent glenohumeral instability.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between June 2009 and June 2017, 145 athletes with recurrent anterior glenohumeral instability underwent surgery with the Latarjet as a primary procedure in our institution. The classic procedure was used in 66 patients, and the congruent arc method was used in 79 patients. Return to sports, range of motion (ROM), the Rowe score, a visual analog scale (VAS) for pain in sports activity, and the Athletic Shoulder Outcome Scoring System (ASOSS) were used to assess functional outcomes. Recurrences were also evaluated. The postoperative bone block position and consolidation were assessed with computed tomography.

RESULTS

In the total population, the mean follow-up was 41.3 months (range, 24-90 months) and the mean age was 25.3 years (range, 18-45 years). In total, 90% of patients were able to return to sports; of these, 91% returned at their preinjury level of play. No significant difference in shoulder ROM was found between preoperative and postoperative results. The Rowe, VAS, and ASOSS scores showed statistical improvement after operation (P < .001). The Rowe score increased from a preoperative mean of 42.8 points to a postoperative mean of 95.2 points (P < .01). Subjective pain during sports improved from 3.2 points preoperatively to 0.7 points at last follow-up (P < .01). The ASOSS score improved significantly from a preoperative mean of 46.4 points to a postoperative mean of 88.4 points (P < .01). No significant differences in shoulder ROM and functional scores were found between patients who received the classic vs congruent arc procedures. There were 5 recurrences (3.5%): 3 dislocations (2%) and 2 subluxations (1%). No significant difference in the recurrence rate was noted between groups. The bone block healed in 134 cases (92%).

CONCLUSION

In athletes with recurrent anterior glenohumeral instability, the Latarjet procedure produced excellent functional outcomes. Most athletes returned to sports at their preinjury level, and the rate of recurrence was very low, regardless of whether the patients received surgery with the classic or congruent arc technique.

Cortical suture button fixation vs. bicortical screw fixation in the Latarjet procedure: a biomechanical comparison

BACKGROUND

The Latarjet procedure traditionally has been performed with 2 screws in an open manner. Recently, cortical suture button fixation for coracoid transfer has been used in hopes of mitigating complications seen with screw placement. The aim of this study was to evaluate a cortical suture button and technique currently available in the United States compared with screw fixation in the Latarjet procedure in a cadaveric model.

METHODS

We randomly assigned 9 matched pairs of fresh-frozen cadaveric shoulders (N = 18) to undergo the Latarjet procedure with either screw fixation or cortical suture button fixation. After fixation, all shoulders underwent biomechanical testing with direct loading on the graft vas a material testing system. Cyclic testing was performed for 100 cycles to determine axial displacement with time; each graft was then monotonically loaded to failure.

RESULTS

The maximum cycle displacement was significantly less for screw fixation vs. cortical suture button fixation (3.1 ± 1.3 mm vs. 8.9 ± 2.1 mm, P < .0001). The total load at failure was 481.1 ± 88.8 N for screws and 175.5 ± 95.8 N for cortical suture buttons (P < .0001). Bony damage to the surrounding anatomy was more extensive at failure in the screw-fixation group.

CONCLUSION

At time zero, the cortical button fixation and technique did not resist direct loads to the graft as much as traditional screw fixation, although bony damage to the surrounding anatomy was more extensive in screw fixation than button fixation. In the event of unanticipated loading, this could place a patient at higher risk of graft migration, which could lead to unintended early outcomes. These results support the need for implants and techniques specifically tailored to the Latarjet procedure and should bring into question the adoption of a cortical button and technique not specific to the procedure.

The Biomechanical Effect of Bone Grafting and Bone Graft Remodeling in Patients With Anterior Shoulder Instability

BACKGROUND

Individual constitutional differences in glenoid shape and bone remodeling require a patient-specific and longitudinal approach to evaluate the biomechanical effects of glenoid bone grafting in patients with anterior shoulder instability.

PURPOSE

To quantify the longitudinal, in vivo, biomechanical effects of bone grafting, bone graft remodeling, and glenoid shape in patients with anterior shoulder instability by means of patient-specific finite element models.

STUDY DESIGN

Descriptive laboratory study.

METHODS

In total, 25 shoulders of 24 patients with anterior shoulder instability and anterior glenoid bone loss underwent an arthroscopic iliac crest bone graft transfer (ICBGT) procedure with either autologous or allogenic bone. Patient-specific finite element simulations based on preoperative, postoperative, and follow-up computed tomography scans were used to quantify the bone-mediated stability ratio (SR) and the distance to dislocation. Additionally, the relationship between glenoid morphological parameters and the SR was assessed.

RESULTS

The ICBGT procedure significantly increased the SR and distance to dislocation in the 2-, 3-, and 4-o'clock directions immediately after the surgical intervention (P < .01) in both the autograft and the allograft groups. Although the SR and distance to dislocation decreased subsequently, autografts showed long-term effects on SR and dislocation distance in the 3-o'clock direction (P < .01) and on SR in the 4-o'clock direction (P < .01). Allografts showed no significant effect on SR and dislocation distance in long-term follow-up (P > .05). Overall, glenoid retroversion as well as cavity depth predicted stability in all 4 dislocation directions, with glenoid cavity depth showing the highest correlation coefficients (R = 0.71, 0.8, 0.73, and 0.7 for 2-, 3-, 4-, and 5-o'clock, respectively).

CONCLUSION

The autologous ICBGT procedure biomechanically improved anterior shoulder stability in long-term follow-up, whereas the use of allografts did not show any bone-mediated biomechanical effect at follow-up due to resorption. Furthermore, in addition to measurements of defect extent, the glenoid depth and version seem to be useful parameters to determine the biomechanical effect and need for glenoid bone grafting in patients with shoulder instability.

CLINICAL RELEVANCE

This study proposes the use of autologous bone grafts for a successful long-term stabilization effect. Additionally, this study proposes additional glenoid morphological measures to predict shoulder stability.

A Biomechanical Comparison of Two Techniques of Latarjet Procedure in Cadaveric Shoulders

Traumatic anterior instability of the shoulder is commonly treated with the Latarjet procedure, which involves transfer of the coracoid process with a conjoint tendon to the anterior aspect of the glenoid. The two most common techniques of the Latarjet are the classical and congruent arc techniques. The aim of this study was to evaluate the difference in force required to dislocate the shoulder after classical and congruent arc Latarjet procedures were performed. Fourteen cadaveric shoulders were dissected and osteotomised to produce a bony Bankart lesion of 25% of the articular surface leading to an “inverted pear-shaped” glenoid. An anteroinferior force was applied whilst the arm was in abduction and external rotation using a pulley system. The force needed to dislocate was noted, and then the shoulders underwent coracoid transfer with the classical and congruent arc techniques. The average force required to dislocate the shoulder after osteotomy was 123.57 N. After classical Latarjet, the average force required was 325.71 N, compared with 327.14 N after the congruent arc technique. This was not statistically significant. In this biomechanical cadaveric study, there is no difference in the force required to dislocate a shoulder after classical and congruent arc techniques of Latarjet, suggesting that both methods are equally effective at preventing anterior dislocation in the position of abduction and external rotation.

Scapular Spine Dimensions and Suitability as a Glenoid Bone Graft Donor Site

BACKGROUND

Current structural bone graft options used for glenoid augmentation in glenohumeral instability have known drawbacks. The scapular spine may be a possible alternative graft choice, but its dimensions and anatomy are not fully reported.

HYPOTHESIS

The scapular spine's harvestable graft dimensions will be similar to harvestable dimensions of the coracoid and iliac crest.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The scapular spine, coracoid, and iliac crest dimensions were recorded and compared bilaterally in 50 patients with 3-dimensional computed tomography imaging. The portion of the scapular spine with the largest harvestable dimensions was quantified and its location defined. Measurements were independently taken by 2 investigators and averaged for the final result.

RESULTS

The scapular spine has 81.5 mm of harvestable length and a "flare" located approximately 49.6 mm lateral to the medial scapular border, where the widest harvestable cross section is located (mean harvestable dimensions: 10.9-mm height, 11.5-mm width). Mean coracoid dimensions were 24-mm length, 14.2-mm height, and 10.6-mm width. Mean iliac crest width was 14.7 mm. In sum, 96% of scapular spines, 85% of coracoids, and 100% of iliac crests exceeded minimum dimensions of 8 mm × 8 mm × 20 mm. The coronal radius of curvature of the glenoid was significantly different from the corresponding plane of all measured structures.

CONCLUSION/CLINICAL RELEVANCE

The scapular spine has dimensions similar to the coracoid and iliac crest in the majority of patients and is therefore appropriate for further investigation as a potential graft choice in glenohumeral instability. A harvest location 49.6 mm lateral to the medial scapular border will provide the largest cross-sectional graft while avoiding the acromial base.

Suture anchor fixation strength in the Latarjet procedure: a biomechanical study in cadavers

BACKGROUND

The use of metallic screws for graft fixation during the Latarjet procedure is not devoid of complications. The purpose of the present cadaver study was to determine the initial strength of coracoid graft fixation using suture anchors and compare it to that of the traditional screw fixation of the graft using a fresh frozen human shoulder cadaver model.

MATERIALS AND METHODS

Twelve unpaired fresh frozen cadaver shoulders were utilized. In the first group, suture anchor fixation of the graft was used, while 3.75-mm cannulated screws were used in the second group. The specimens were then cyclically loaded from 5 to 150 N at a speed of 0.05 mm/s for 100 cycles. After cyclic loading, each specimen was then loaded at a constant rate of 0.5 mm/s until 7 mm of displacement. Cyclic elongation, peak-to-peak displacement, stiffness and maximum load were measured.

RESULTS

There were no significant differences between the traditional screw fixation and fixation using suture anchors in elongation, peak-to-peak displacement, stiffness and maximum load.

CONCLUSIONS

In this study, traditional screw fixation and fixation using suture anchors did not significantly affect biomechanical performance in a classic Latarjet procedure.

Bony Reconstruction of the Anterior Glenoid Rim

Recurrent anterior shoulder instability is associated with glenohumeral bone loss. Glenoid deficiency compromises the concavity-compression mechanism. Medial Hill-Sachs lesions can result in an off-track humeral position. Anterior glenoid reconstruction or augmentation prevents recurrence by addressing the pathomechanics. In Bristow and Latarjet procedures, the coracoid process is harvested for conjoint tendon transfer, capsular reinforcement, and glenoid rim restoration. Complications and the nonanatomic nature of the procedure have spurred research on graft sources. The iliac crest is preferred for autogenous structural grafts. Tricortical, bicortical, and J-bone grafts have shown promising results despite the historical association of Eden-Hybinette procedures with early degenerative joint disease. Allogeneic osteochondral grafts may minimize the risk of arthropathy and donor site morbidity. Tibial plafond and glenoid allografts more closely match the native glenoid geometry and restore the articular chondral environment, compared with conventional grafts. Graft availability, cost, risk of disease transmission, and low chondrocyte viability have slowed the acceptance of osteochondral allografts.

Distal Clavicular Osteochondral Autograft Augmentation for Glenoid Bone Loss: A Comparison of Radius of Restoration Versus Latarjet Graft

BACKGROUND

Bone loss in shoulder instability is a well-recognized cause of failure after stabilization surgery. Many approaches have been described to address glenoid bone loss, including coracoid transfer. This transfer can be technically difficult and has been associated with high complication rates. An ideal alternative to coracoid transfer would be an autologous source of fresh osteochondral graft with enough surface area to replace significant glenoid bone loss. The distal clavicle potentially provides such a graft source that is readily available and low-cost.

PURPOSE

To evaluate distal clavicular autograft reconstruction for instability-related glenoid bone loss, specifically comparing the width of the clavicular autograft with the width of an ipsilateral coracoid graft as prepared for a Latarjet procedure. Further, we sought to compare the articular cartilage thickness of the distal clavicle graft with that of the native glenoid.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-seven fresh-frozen cadaver specimens were dissected, and an open distal clavicle excision was performed. The coracoid process in each specimen was prepared as has been described for a classic Latarjet coracoid transfer. In each specimen, the distal clavicle graft was compared with the coracoid graft for size and potential of glenoid articular radius of restoration. The distal clavicle graft was also compared with the native glenoid for cartilage thickness.

RESULTS

In all specimens, the distal clavicle grafts provided a greater radius of glenoid restoration than the coracoid grafts ( P < .0001). On average, the clavicular graft was able to reconstruct 44% of the glenoid diameter, compared with 33% for the coracoid graft ( P < .0001). The articular cartilage of the glenoid was significantly thicker (1.4 mm thicker, P < .0001) than that of the distal clavicular autograft (average ± SD, 3.5 ± 0.6 mm vs 2.1 ± 0.8 mm, respectively). When specimens with osteoarthritis were excluded, this difference decreased to 0.97 mm when compared with the clavicular cartilage ( P = .0026).

CONCLUSION

The distal clavicle autograft can restore a significantly greater glenoid bone deficit than the Latarjet procedure and has the additional benefit of restoring articular cartilage to the glenoid. The articular cartilage thickness of the distal clavicle is within 1.4 mm of that of the native glenoid.

CLINICAL RELEVANCE

The distal clavicular autograft may be a suitable option for reconstruction of instability-related glenoid bone loss. This graft provides a structural osteochondral autograft with a broader radius of reconstruction than that of a coracoid graft, is locally available, has minimal donor site morbidity, is anatomic, and provides articular cartilage.

Influence of screw type and length on fixation of anterior glenoid bone grafts

BACKGROUND

Bone-grafting procedures for recurrent shoulder instability produce low recurrence rates, although they are associated with complications such as graft non-union. Inadequate screw purchase is considered to play a causative role. However, excessive screw length can endanger neurovascular structures. The present study aimed to investigate how type and length of screws influences construct rigidity in a simplified glenoid model.

METHODS

Testing was performed on composite polyurethane foam models with material properties and abstract dimensions of a deficient glenoid and an bone graft. Three screw types (cannulated 3.75 mm and 3.5 mm and solid 4.5 mm) secured the graft in a bicortical-bicortical, bicortical-unicortical and unicortical-unicortical configuration. Biomechanical testing consisted of applying axial loads when measuring graft displacement.

RESULTS

At 200 N, graft displacement reached 0.74 mm, 0.27 mm and 0.24 mm for the unicortical-unicortical and 0.40 mm, 0.25 mm and 0.24 mm for the unicortical-bicortical configuration of the 3.75 mm, 3.5 mm and 4.5 mm screw types. The 3.75 mm screw incurred significant displacements in the unicortical configurations compared to the bicortical-bicortical method (p < 0.001).

CONCLUSIONS

The present study demonstrates that common screw types resist physiological shear loads in a bicortical configuration. However, the 3.75 mm screws incurred significant displacements at 200 N in the unicortical configurations. These findings have implications regarding hardware selection for bone-grafting procedures.

Individualized coracoid osteotomy and 3D congruent arc reconstruction of glenoid for the treatment of recurrent anterior shoulder dislocation

Background

The present study investigated individualized coracoid osteotomy for 3D congruent arc glenoid reconstruction and evaluated the clinical outcomes in recurrent anterior shoulder dislocation.

Methods

From January 2005 to July 2015, 78 patients with glenoid defect underwent coracoid and conjoint tendon transposition. The patients were divided into the individualized group (n = 34) and the non-individualized group (n = 44). All patients had CT data to reconstruct the shoulder model using Mimics software. In the individualized group, the individual coracoid osteotomy and bone fixation position parameters were measured from preoperative planification through simulating a 3D congruent arc glenoid reconstruction model. The non-individualized group underwent classic Bristow-Latarjet (B-L) procedure. The postoperative evaluation parameters included 3D congruent arc index, coracoid bone position, shoulder osteoarthritis index (Samilson-Prieto) and shoulder function score (Rowe, Constant-Murley score).

Results

The mean follow-up time was 51.0 months (ranging from 24 to 146). The individualized group got 3D congruent arc reconstruction of the glenoid by postoperative CT scanning. Bone position was more precise in the individual group than that in the B-L group. There was a lower incidence of shoulder osteoarthritis (Samilson-Prieto) in the individual group compared with that in the B-L group: 0 vs 13.6% (mild 6/44, P = 0.027), respectively. No significant difference was observed between the individual and B-L groups in rate of re-dislocation: 0 vs 4.5% (2/44, P = 0.315), respectively. The postoperative Rowe and Constant score was significantly improved but was not significantly different between the two groups.

Conclusion

The individual procedure achieved 3D congruent arc glenoid reconstruction. The clinical effects in patients with medium glenoid defect were good, especially the low incidence of shoulder osteoarthritis in middle-term follow-up.

Electronic supplementary material

The online version of this article (10.1186/s13018-017-0687-8) contains supplementary material, which is available to authorized users.

Management of Glenoid Bone Loss with Anterior Shoulder Instability: Indications and Outcomes

PURPOSE OF REVIEW

Glenoid Bone Loss is a commonly encountered problem in anterior shoulder instability. In this article, we review current techniques for diagnosis, indications and management of glenoid bone loss.

RECENT FINDINGS

Multiple bone grafting techniques are available depending on the glenoid defect size including the coracoid, distal clavicle, iliac crest, and allograft distal tibia. Advancement in imaging methods allows for more accurate quantification of bone loss. Indications and techniques are continuing to evolve, and emerging evidence suggests that smaller degrees of bone loss "subcritical" may be best treated with bone grafting. Future directions for innovation and investigation include improved arthroscopic techniques and a refinement of indications for the type of bone grafts and when to indicate a patient of arthroscopic repair versus glenoid bone grafting for smaller degrees of bone loss to ensure successful outcome.

Biomechanical Analysis of Latarjet Screw Fixation: Comparison of Screw Types and Fixation Methods

PURPOSE

To compare the initial fixation stability, failure strength, and mode of failure of 5 different screw types and fixation methods commonly used for the classic Latarjet procedure.

METHODS

Thirty-five fresh-frozen cadaveric shoulder specimens were allocated into 5 groups. A 25% anteroinferior glenoid defect was created, and a classic Latarjet coracoid transfer procedure was performed. All grafts were fixed with 2 screws, differing by screw type and/or fixation method. The groups included partially threaded solid 4.0-mm cancellous screws with bicortical fixation, partially threaded solid 4.0-mm cancellous screws with unicortical fixation, fully threaded solid 3.5-mm cortical screws with bicortical fixation, partially threaded cannulated 4.0-mm cancellous screws with bicortical fixation, and partially threaded cannulated 4.0-mm captured screws with bicortical fixation. All screws were stainless steel. Outcomes included cyclic creep and secant stiffness during cyclic loading, as well as load and work to failure during the failure test. Intergroup comparisons were made by a 1-way analysis of variance.

RESULTS

There were no significant differences among different screw types or fixation methods in cyclic creep or secant stiffness after cyclic loading or in load to failure or work to failure during the failure test. Post-failure radiographs showed evidence of screw bending in only 1 specimen that underwent the Latarjet procedure with partially threaded solid cancellous screws with bicortical fixation. The mode of failure for all specimens analyzed was screw cutout.

CONCLUSIONS

In this biomechanical study, screw type and fixation method did not significantly influence biomechanical performance in a classic Latarjet procedure. When performing this procedure, surgeons may continue to select the screw type and method of fixation (unicortical or bicortical) based on preference; however, further studies are required to determine the optimal method of treatment.

CLINICAL RELEVANCE

Surgeons may choose the screw type and fixation method based on preference when performing the Latarjet procedure.

Anatomic and Biomechanical Comparison of the Classic and Congruent-Arc Techniques of the Latarjet Procedure

BACKGROUND

The Latarjet procedure is commonly performed using either the classic or the congruent-arc technique. Each technique has potential clinical advantages and disadvantages. However, data on the anatomic and biomechanical effects, benefits, and limitations of each technique are limited. Hypothesis/Purpose: To compare the anatomy and biomechanical fixation strength (failure load) between the 2 techniques. It was hypothesized that the classic technique would have superior initial fixation when compared with the congruent-arc technique and that this would be affected by sex and coracoid size.

STUDY DESIGN

Controlled laboratory study.

METHODS

A biomechanical cadaver study was performed with 20 pairs of male and female shoulders. One of each pair of shoulders was randomly assigned to receive the classic or congruent-arc technique. Coracoid and glenoid anatomic measurements were collected before biomechanical testing. A tensile force was applied through the conjoined tendon to replicate forces experienced by the coracoid graft in the early postoperative period, and the failure load was determined for each specimen.

RESULTS

The mean ± SD surface area available for fixation was 263 ± 63 mm² in the classic technique compared with 177 ± 63 mm² in the congruent-arc group ( P < .001). 36% of the glenoid width was recreated in the classic group and 50% in the congruent-arc group ( P < .001). The congruent-arc technique resulted in a significantly lower ( P = .005) mean failure load (239 ± 91 N) compared with the classic technique (303 ± 114 N). Failure load was significantly higher in males ( P = .037); male specimens had a mean failure load of 344 ± 122 N for the classic technique and 289 ± 73 N for the congruent-arc technique, and females had a mean failure load of 266 ± 98 N and 194 ± 84 N, respectively.

CONCLUSION

In this biomechanical model, the classic technique of the Latarjet procedure provided a greater surface area for healing to the glenoid and superior initial fixation when compared with the congruent-arc technique. The congruent-arc technique allowed restoration of a larger glenoid defect.

CLINICAL RELEVANCE

The classic and congruent-arc techniques of coracoid transfer have anatomic and biomechanical advantages and disadvantages that should be considered when choosing between the 2 techniques.

Distal Tibia Allograft Glenoid Reconstruction in Recurrent Anterior Shoulder Instability: Clinical and Radiographic Outcomes

PURPOSE

To assess the clinical and radiographic outcomes of patients with recurrent anterior shoulder instability treated with fresh distal tibia allograft (DTA) glenoid reconstruction.

METHODS

Consecutive patients with a minimum 15% anterior glenoid bone loss associated with recurrent anterior instability who underwent stabilization with DTA glenoid reconstruction were retrospectively reviewed. Patients were evaluated with the American Shoulder and Elbow Society score, Western Ontario shoulder instability index, and single numerical assessment evaluation score at a minimum 2 years after surgery. All patients also underwent postoperative imaging evaluation with computed tomography where graft incorporation and allograft angle were measured. Statistical analysis was performed with paired t-tests, with P < .05 considered significant.

RESULTS

A total of 27 patients (100% male) with an average age of 31 ± 5 years and an average follow-up of 45 months (range, 30-66) were included. There were significant improvements in preoperative to postoperative American Shoulder and Elbow Society score (63-91, P < .01), Western Ontario shoulder instability index (46% to 11% of normal, P < .01), and single numerical assessment evaluation score (50-90.5, P < .01) outcomes. Analysis of computed tomography data at an average 1.4 years postoperatively (available for 25 patients) showed an allograft healing rate of 89% (range, 80% to 100%), average allograft angle of 14.9° (range, 6.6° to 29.3°), and average allograft lysis of 3% (range, 0% to 25%). Grafts with lesser allograft angles (<15°) were better opposed to the anterior glenoid, showing superior healing and graft incorporation. There were no cases of recurrent instability.

CONCLUSIONS

At an average follow-up of 45 months, fresh DTA reconstruction for recurrent anterior shoulder instability results in a clinically stable joint with excellent clinical outcomes and minimal graft resorption. Optimal allograft placement resulted in superior bony incorporation with the native glenoid.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Remplissage of an Off-track Hill-Sachs Lesion Is Necessary to Restore Biomechanical Glenohumeral Joint Stability in a Bipolar Bone Loss Model

PURPOSE

To validate the glenoid track concept in a cadaveric bipolar bone loss model and to test whether "on-track" and "off-track" lesions can be stabilized with Bankart repair (BR) with or without Hill-Sachs remplissage (HSR).

METHODS

Eight fresh-frozen cadaveric shoulders were tested in a custom apparatus with passive axial rotation and then progressive translational loading (10 to 40 N) at mid-range (60°) and end-range external rotation (90°). Injury conditions included glenoid bone loss of 15% with on-track (15%) and off-track (30%) Hill-Sachs lesions. Repair conditions included BR with HSR and BR without HSR.

RESULTS

For on-track lesions, engagement occurred with translation testing in one shoulder (12.5%) at end-range rotation. After BR, engagement was prevented for this shoulder. For off-track lesions, engagement with translation testing occurred in 8 shoulders (100%) at end-range rotation and in 6 (75%) at mid-range rotation. After BR, engagement was prevented in 4 of 6 engaging shoulders (67%) at mid-range rotation but was prevented in zero of 8 (0%) at end-range rotation. Adding HSR prevented engagement in all 14 engaging shoulders with off-track lesions (100%). BR with HSR resulted in supraphysiological stiffness for off-track lesions at mid- and end-range rotation (13.3 N/m vs 7.0 N/m and 10.0 N/m vs 5.0 N/m, P = .0002) and for on-track lesions at end-range rotation (10.1 N/m vs 5.0 N/m, P = .0002). Stiffness of BR with HSR was not different from the intact shoulder for on-track lesions at mid-range rotation (7.2 N/m vs 7.0 N/m, P > .99).

CONCLUSIONS

The patterns of engagement of Hill-Sachs lesions with a 15% glenoid defect in this model give support to the glenoid track concept. BR plus remplissage resulted in supraphysiological shoulder stiffness but was necessary to prevent engagement of off-track bipolar bone lesions.

CLINICAL RELEVANCE

This biomechanical study provides evidence to aid in surgical decision making by examining the effects of bipolar bone loss and soft-tissue reconstruction on shoulder stability.

Latarjet Fixation: A Cadaveric Biomechanical Study Evaluating Cortical and Cannulated Screw Fixation

BACKGROUND

Attritional bone loss in patients with recurrent anterior instability has successfully been treated with a bone block procedure such as the Latarjet. It has not been previously demonstrated whether cortical or cancellous screws are superior when used for this procedure.

PURPOSE

To assess the strength of stainless steel cortical screws versus stainless steel cannulated cancellous screws in the Latarjet procedure.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten fresh-frozen matched-pair shoulder specimens were randomized into 2 separate fixation groups: (1) 3.5-mm stainless steel cortical screws and (2) 4.0-mm stainless steel partially threaded cannulated cancellous screws. Shoulder specimens were dissected free of all soft tissue and a 25% glenoid defect was created. The coracoid process was osteomized, placed at the site of the glenoid defect, and fixed in place with 2 parallel screws.

RESULTS

All 10 specimens failed by screw cutout. Nine of 10 specimens failed by progressive displacement with an increased number of cycles. One specimen in the 4.0-mm screw group failed by catastrophic failure on initiation of the testing protocol. The 3.5-mm screws had a mean of 274 cycles (SD, ±171 cycles; range, 10-443 cycles) to failure. The 4.0-mm screws had a mean of 135 cycles (SD, ±141 cycles; range, 0-284 cycles) to failure. There was no statistically significant difference between the 2 types of screws for cycles required to cause failure (P = .144).

CONCLUSION

There was no statistically significant difference in energy or cycles to failure when comparing the stainless steel cortical screws versus partially threaded cannulated cancellous screws.

CLINICAL RELEVANCE

Latarjet may be performed using cortical or cancellous screws without a clear advantage of either option.

Arthroscopic versus open shoulder stabilization: current practice patterns in the United States

PURPOSE

The purpose of this study was to investigate current trends in arthroscopic and open shoulder stabilization in the United States.

METHODS

Patients who underwent arthroscopic shoulder stabilization (Current Procedural Terminology code 29806) or open stabilization (Current Procedural Terminology codes 23455 [open Bankart repair], 23460 [anterior bone block], and 23462 [coracoid transfer]) were identified using a national database of insurance billing records during the years 2004 through 2009. Demographic data were recorded for each patient.

RESULTS

From 2004 through 2009, there were 23,096 cases of shoulder stabilization, of which 84% (19,337) were arthroscopic and 16% (3,759) were open procedures. There were 17,241 male patients (75%) and 5,855 female patients (25%). The incidence of arthroscopic shoulder stabilization nearly doubled during the period studied, increasing from 11.8 cases for every 10,000 patients in 2004 to 22.9 cases for every 10,000 patients in 2009. The percentage of arthroscopic stabilizations increased from 71% of stabilization procedures in 2004 to 89% in 2009, whereas the percentage of open stabilizations decreased from 29% in 2004 to 11% in 2009 (P < .0001). Among open procedures, a significant decline in the incidence of open Bankart repair was observed, from 4.5 cases for every 10,000 patients in 2004 to 2.2 cases for every 10,000 patients in 2009 (P < .0001), whereas the performance of open coracoid transfer increased from 0.17 cases per 10,000 patients in 2004 to 0.40 cases per 10,000 patients in 2009 (P < .0001). For both arthroscopic and open stabilization, the group aged 10 to 19 years had the highest rate of surgery (29%), followed by the group aged 20 to 29 years (25%).

CONCLUSIONS

The current data indicate that arthroscopic stabilization is performed in nearly 90% of shoulder stabilization surgeries and nearly doubled in incidence from 2004 to 2009 in the United States. Additional research is needed to further investigate the long-term clinical outcomes of this practice pattern.

LEVEL OF EVIDENCE

Level IV, retrospective database review.

Humeral head reconstruction for Hill-Sachs defects: a biomechanical comparison of 2 fixation techniques for bone grafting

PURPOSE

The purpose of this biomechanical study was to compare anterograde with retrograde screw fixation for allograft reconstruction of Hill-Sachs defects.

METHODS

In 8 pairs of fresh-frozen humeral heads, a 40% Hill-Sachs defect was created. The resultant wedge-shaped osteochondral fragment was used as allograft. For each technique, two 3.75-mm screws were used for fixation. To test the strength of fixation, a custom tool was used that would apply load to the graft. By use of a materials testing machine, a staircase cyclic loading protocol was performed (500 cycles at 10, 20, 30, and 40 N) and then load to failure. Graft displacement was measured by an optical tracking system.

RESULTS

For the 2 techniques, graft displacement increased with increasing load and increasing number of cycles up to a mean of 0.9 ± 0.42 mm for anterograde fixation and 1.1 ± 0.79 mm for retrograde fixation. This increase was significant within each technique across all 4 loading levels (P < .05). However, there were no significant differences in graft displacement between the 2 techniques at any loading level or number of cycles (P = .16 to P = .96). In addition, the load to failure between the anterograde and retrograde techniques (98.5 N and 95.6 N, respectively) was not significantly different (P = .706).

CONCLUSIONS

The initial fixation and failure strength of anterograde and retrograde graft fixation techniques for substantial Hill-Sachs defects do not significantly differ in a biomechanical cadaveric model.

CLINICAL RELEVANCE

This biomechanical study supports that in an engaging Hill-Sachs defect, both anterograde and retrograde screw fixation techniques can be used for fixation of humeral head allografts.

Suture anchor fixation of bony Bankart fractures: comparison of single-point with double-point "suture bridge" technique

BACKGROUND

As an alternative to the standard single-point suture-anchor technique, a suture-bridge technique has been described for the treatment of bony Bankart fractures. There is, however, little evidence supporting one technique over the other. Purpose/

HYPOTHESIS

To compare the failure strength, fixation stability, and loading mechanics of the 2 techniques for the fixation of bony Bankart fractures. We hypothesized that use of the double-point suture-bridge technique would result in superior strength and fixation stability because of the increased compression and contact area between the bony fragment and glenoid fracture site.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 16 shoulders (8 pairs) were tested with an intact glenoid, after creation of a 15% bony Bankart fracture, and after fragment fixation using a single-point or suture-bridge technique. Paired specimens were randomly assigned to each technique. Cyclic progressive loading was applied via a materials testing machine to the glenoid concentrically and eccentrically according to a staircase protocol. Failure strength, fragment displacement, glenoid strain load transfer, and contact area were quantified.

RESULTS

No significant differences in failure strength were found between the single-point and suture-bridge techniques (mean strength, 74 ± 28 N vs 77 ± 56 N, respectively; P = .91). Additionally, no significant differences were found for glenoid load transfer (P ≥ .318) and glenohumeral joint contact (P = .357) between the 2 techniques. Centralized loading, however, produced significant differences in fragment displacement at 5, 150, and 200 N (P ≤ .045), with the single-point technique permitting greater fragment displacement in all cases (0.06-0.28 mm). Similarly, eccentric loading caused significantly greater fragment displacement with the single-point technique at ≥25 N compared with the suture-bridge technique (mean range, 0.38-0.63 mm vs 0.14-0.19 mm, respectively; .009 ≤ P ≤ .048).

CONCLUSION

Single-point and suture-bridge techniques for the fixation of bony Bankart fragments have equivalent failure strengths and load transfers. The suture-bridge technique does provide statistically greater initial fracture fragment stability; however, the clinical implications of this are presently unknown.

CLINICAL RELEVANCE

This study will aid in the selection of the optimal repair technique for bony Bankart fractures by providing important insights into the quality of initial fixation and ultimate strength.