Biomechanical comparison of open and arthroscopic Latarjet procedures

Arthroscopic Latarjet procedure: current concepts and surgical techniques

The Latarjet procedure is a surgical procedure that can effectively restore glenohumeral stability, especially in patients with anterior shoulder instability and glenoid bone loss. Many studies have shown comparable clinical outcomes between patients undergoing the arthroscopic Latarjet procedure and those undergoing traditional open methods or other glenohumeral joint stabilization procedures. However, the arthroscopic Latarjet procedure is a challenging technique due to the unfamiliar portal placements, proximity of neurovascular structures, and serious postoperative complications. The arthroscopic Latarjet procedure has not yet been widely applied, and a clear understanding of the anatomical structure and the precise methods is required prior to operation performance. Satisfactory clinical outcomes can be achieved by thorough preoperative planning and proper implant fixation methods.

Bone formation of the coracoid bone graft after the Bristow procedure assessed using three-dimensional computed tomography

BACKGROUND

The Bristow procedure has been shown to be a reliable method to prevent recurrent anterior shoulder instability by compensating for glenoid bone loss and producing the sling effect. The degree of postoperative morphological change in the coracoid bone graft is speculated to influence glenohumeral joint stability; however, the details of these changes after the Bristow procedure remain unknown. This study was performed to quantify the postoperative change in the coracoid bone graft volume as assessed by three-dimensional computed tomography (3D-CT).

METHODS

The Bristow procedure was performed on 17 shoulders in 17 patients from August 2018 to January 2020. All patients were men, and their mean age at surgery was 17.9 years. The mean follow-up duration was 21.4 months. Within the first week after the operation (Time 0) and at the final follow-up, 3D-CT was used to determine the total coracoid bone graft volume. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) shoulder score, the University of California Los Angeles (UCLA) shoulder score, and the Western Ontario Shoulder Instability Index (WOSI).

RESULTS

The mean volume of the total coracoid bone graft was 1.26 ± 0.29 cm3 at Time 0 and 1.90 ± 0.36 cm3 at the final follow-up (p < 0.0001). The mean JOA score, UCLA score, and WOSI were significantly better at the final follow-up than preoperatively (p < 0.001). No postoperative infection, neurovascular injury, or recurrent instability of the glenohumeral joint occurred.

CONCLUSIONS

In the Bristow procedure, the volume of the total coracoid bone graft as shown by 3D-CT was significantly greater at the final follow-up than at Time 0, and bone formation of the coracoid bone graft was found after the Bristow procedure.

Arthroscopic Anterior Shoulder Capsular Reconstruction Using Human Acellular Dermal Graft in Conjunction With Anatomic Glenoid Reconstruction

Capsular insufficiency of the shoulder associated with glenoid bone loss poses a major challenge to orthopaedic surgeons in the management of recurrent anterior instability. Multiple surgical techniques have been described in the literature with varying rates of success, and the majority of these are open techniques. We present a complete arthroscopic technique for anterior capsular reconstruction using acellular human dermal allograft patch in conjunction to an anatomic glenoid reconstruction using a distal tibial allograft in the lateral decubitus position. If the capsular insufficiency is determined irreparable after glenoid reconstruction, the acellular human dermal graft patch is prepared, inserted into the shoulder joint, and appropriately fixed using suture anchors on both glenoid and humerus, all through arthroscopic portals.

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.

Arthroscopic Latarjet Procedure: Indications, Techniques, and Outcomes

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The proposed advantages of the arthroscopic approach in the Latarjet procedure for shoulder dislocation include improved visualization for accurate positioning of the coracoid graft, the ability to address any associated intra-articular pathologies, and the diminished potential for the formation of postoperative scar tissue and stiffness associated with an open procedure.

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Young age, the presence of glenoid and/or humeral bone loss, a history of dislocation, a history of failed arthroscopic stabilization surgery, and an active lifestyle are all associated with recurrent dislocation and are relative indications for an osseous augmentation procedure.

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Both the open and arthroscopic Latarjet procedures result in substantial improvements in patient function, with comparable rates of recurrent instability and complication profiles.

Arthroscopic Latarjet: Technique Description and Preliminary Results. Study of the First 30 Cases

Objective  Arthroscopic Latarjet has been performed with the aim to be an accurate technique with a low incidence of complications. The aim of the present study was to briefly describe the technique and to evaluate the shot-term complications following arthroscopic Latarjet procedure to correct anterior shoulder dislocation with glenoid bone loss.

Methods  Retrospective study with 30 subjects with anterior shoulder instability, submitted to arthroscopic Latarjet. Intraoperative and short-term postoperative complications were recorded, as well as the rate of revision surgery.

Results  Five cases had complication (16.7%), and in the last 10 cases no complication occurred. In 1 case (3.3%), it was required to reverse for open surgery due to a fracture of the coracoid process during fixation in the glenoid. No other intraoperative complication occurred. No infection was observed. Two cases (6.7%) evolved with temporary neuropraxia of the musculocutaneous nerve, totally reversed with physiotherapy. With a follow-up from 6 to 26 months, 2 patients (6.7%) required a new intervention for graft/screws removal and release of the joint due to excessive limitation in external rotation. There was no case of recurrence.

Conclusion  Even in an initial learning curve, arthroscopic Latarjet demonstrated a low rate of short-tem complications and was a safe procedure for treating anterior dislocation of the shoulder with glenoid bone loss.

A pilot study of blood supply of the coracoid process and the coracoid bone graft after Latarjet osteotomy

Latarjet osteotomy is still one of the most reliable and commonly used surgeries in treating recurrent anterior shoulder dislocation. The coracoid process (CP) is the main structure of this surgery. However, the blood supply of CP is not fully understood, and the extent of destruction of blood supply of coracoid bone graft after Latarjet osteotomy procedure is still controversial. Five embalmed cadaveric upper limbs specimens were employed for macro observation of the blood supply of CP. The conjoint tendon (CT) and CP interface were dissected for histology. Sixteen fresh frozen shoulder specimens were used for perfusion and micro CT scanning. Eight specimens were used to present the whole vessel structure of CP. The other eight underwent Latarjet osteotomy procedure. The coracoid bone grafts in both groups were scanned to clarify the remnant blood supply. It was found that the CP was nourished by supra-scapular artery (SSA), thoracic-acromial artery and branch from second portion of the axillary artery (AA). After Latarjet osteotomy procedure, no artery from CT was detected to penetrate the CP at its attachment. Only in one specimen the blood vessel that originated from the CT penetrated the bone graft at the inferior side. Therefore, most of the blood supply was destroyed although there is a subtle possibility that the vessels derived from the CT nourished the inferior side of the CP. In a nutshell, CP is a structure with rich blood supply. The traditional Latarjet osteotomy procedure would inevitably cut off the blood supply of the coracoid bone graft.

Learning Curves in the Arthroscopic Latarjet Procedure: A Multicenter Analysis of the First 25 Cases of 5 International Surgeons

PURPOSE

To analyze the learning curves of 5 experienced, fellowship-trained shoulder surgeons and their respective 25 first arthroscopic Latarjet cases in regard to surgical time, graft placement, complication rates, and recurrent instability.

METHODS

The first 25 arthroscopic Latarjet procedures of 5 surgeons were retrospectively analyzed in an international multicenter setting, and thus 125 patients were included in this study. The surgical time, intraoperative and postoperative events out of the ordinary, and graft positioning were examined.

RESULTS

The 125 patients consisted of 16 women (12.8%) and 109 men (87.2%). In 81.6% (n = 102), surgery was undertaken as a first-line procedure, whereas 18.4% (n = 23) were revisions. Surgical time decreased significantly from an average of 123.8 minutes (range 70 to 210) to 92.6 minutes (range 50 to 160) from the first 5 cases to the last 5 cases of each surgeon within a period of <2 years. Overall, 22 events in 21 patients requiring additional treatment were reported (17.6%). Five (4%) were unlikely to affect final outcome and did not require revision surgery. Twelve (9.6%) required revision surgery that was not trauma related yet was prone to affect outcomes. Five events were trauma-related (4%), 4 requiring revision surgery and 1 treated conservatively. Overall, 6 patients (4.8%) had recurrent shoulder instability, 3 as a result of a traumatic event. Conventional radiology showed the bone-block in ideal positioning in 93 cases (74.4%), flush with the glenoid in a true anteroposterior view. In 3 cases (2.4%), it was considered too high, 15 too low (12%), 5 too lateral (4%), and 15 too medial (12%). Some patients had combinations of the above.

CONCLUSION

This analysis shows that surgical time in arthroscopic Latarjet can be significantly reduced after only 20 cases. However, complication rates did not decrease over this time. The authors believe that the arthroscopic Latarjet is a challenging yet viable technique to treat anterior shoulder instability, achieving results equal to the open technique with advantages of the arthroscopic setting.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

[Recurrent instability and instability arthropathy]

Capsulolabral reconstruction (Bankart repair) is recommended as the first line treatment in young and functionally demanding active patients with anteroinferior shoulder instability, due to the high tendency to recurrent dislocation. This has become established both for arthroscopic and open primary shoulder stabilization with good clinical outcome; nevertheless, recurrence of dislocation is reported in up to 25% of patients. Risk factors for failed surgery are patient (e.g. young age, male gender and contact sports) and surgery (e.g. primarily underestimated glenoid bone loss, Hill-Sachs lesion, non-treatment of bipolar defects or malpositioned anchors) related. In the management of recurrent instability, it is necessary to carry out a thorough clinical investigation in addition to extended diagnostics with X‑ray and computed tomography. A second Bankart repair is only indicated in patients with low demands and without any glenoid bone loss. In the majority of patients, bony augmentation of the glenoid is necessary and realized by coracoid or iliac crest bone block transfer. The Latarjet procedure is biomechanically advantageous due to the additional sling effect of the conjoined tendons and both techniques show good clinical outcomes and a low recurrence rate. Furthermore, engaging Hill-Sachs lesions also require additional treatment. Remplissage of the infraspinatus muscle, iliac crest bone block transfer and partial joint replacement are viable options. A final consensus for treatment of Hill-Sachs lesions has yet to be defined. Dislocation arthropathy is an underestimated complication as a result of frequent recurrent dislocations. After development of dislocation arthropathy, patients reported a painful restriction of range of motion rather than instability. Arthroscopic arthrolysis and comprehensive arthroscopic management (CAM procedure) are possible joint-preserving treatment options.

Clinical outcomes and radiologic assessment of a modified suture button arthroscopic Latarjet procedure

Background

As several neurologic and hardware complications have been reported with screw fixation. Suture buttons are used to serve as an alternative to screw fixation to obtain better outcome and to reduce the complication. The purpose of this study was to observe the clinical outcomes and make the radiologic assessment of a modified suture button (MSB) arthroscopic Latarjet procedure.

Methods

A total of ninty-one patients with recurrent shoulder joint dislocation who underwent MSB arthroscopic Latarjet procedure was retrospectively reviewed. Fifty cases identified from the chart review met the inclusion criteria. The clinical outcomes and position of the grafts, glenohumeral degeneration, and graft healing condition were assessed postoperatively in a follow-up with at least one and half of a year.

Results

All the fifty patients were satisfied with their clinical outcome. The overall complication rate was 4% in this study. The mean visual analog scale score, the affected shoulder active mobility in Ers(external rotation at the side), Era(external rotation in abduction) decreased significantly; the ASES score, Rowe score, Walch-Duplay score improved significantly. CT scans in the sagittal view showed that grafts in 88% of cases were in good position, grafts in 12% of cases were fixed too superiorly and inferiorly. In the axial view grafts in forty cases were flush with the glenoid rim, ten were considered as too lateral. The ten grafts became remodeled and were more flush with the glenoid rim in the follow-up.

Conclusions

The MSB arthroscopic Latarjet procedure provides excellent outcome with few complications, and no degenerative changes were observed in the follow-up. Moreover, the graft fixed too laterally presented a phenomenon of remodeling and became flush with the glenoid rim over time.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2544-x) contains supplementary material, which is available to authorized users.

Arthroscopy-assisted Trillat procedure for anterior shoulder instability: Surgical technique and preliminary clinical results

The Trillat procedure performed as open surgery to treat anterior shoulder instability has been proven effective in preventing recurrences and restoring range of motion. An arthroscopically assisted variant of the Trillat procedure is described here, together with the preliminary clinical results in 18 patients treated between 2011 and 2014. After a mean follow-up of 24.7±9.8 months, the clinical outcomes were very satisfactory, with a Walch-Duplay score of 81.5±18.0, a Rowe score of 83.6±16.0, and 94% of satisfied or very satisfied patients. Mean operative time was 55±13min. No recurrences were recorded. As an easily performed procedure that provides good clinical outcomes, the arthroscopically assisted Trillat procedure is a simple and reproducible alternative to arthroscopic Latarjet procedure, which is still reserved for highly experienced surgical teams.

Arthroscopic Latarjet Procedure With Anterior Capsular Reconstruction: Clinical Outcome and Radiologic Evaluation With a Minimum 2-Year Follow-Up

PURPOSE

To investigate the clinical and radiographic outcomes of the modified arthroscopic Latarjet procedure at a minimum of 2 years after surgery.

METHODS

Patients who had traumatic unidirectional anterior shoulder instability and treated with a modified arthroscopic Latarjet procedure were included. During surgery, the anterior capsule was preserved and repaired back to the glenoid after the coracoid transfer. The clinical results (range of motion, American Shoulder and Elbow Surgeons [ASES] score, Constant-Murley score, and Rowe score) and computed tomographic results were followed.

RESULTS

From February 2013 to September 2014, 52 consecutive patients were included. The average duration of follow-up was 28.4 months (range, 24.0-41.7 months). At final follow-up, no recurrent dislocation had occurred. The ASES score and Rowe score improved significantly (ASES score from 85.6 ± 12.7 before surgery to 93.6 ± 5.4 after surgery, P < .0001; Rowe score from 41.5 ± 7.2 before surgery to 92.2 ± 8.7 after surgery, P < .0001). No significant change was found regarding range of motion and the Constant-Murley score. Bone union was achieved in all cases. The transferred coracoid was at the level of the glenoid in all cases. The transferred coracoid was placed below the equator in 48 of 52 cases (92.3%). The orientation of the screw was 22.6° ± 10.8°. Bone resorption around the proximal screw was significantly more prominent than that around the distal screw (P < .0001).

CONCLUSIONS

The arthroscopic Latarjet procedure with concomitant anterior capsular reconstruction can achieve satisfactory clinical outcomes for the treatment of anterior shoulder instability with marked glenoid bone loss at a minimum of 2 years' follow-up. A satisfactory coracoid graft position, proper screw orientation, and high healing rate of the transferred coracoid can be expected. Bone resorption around the proximal screw is more severe than that around the distal screw.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Three-dimensional volume measurement of coracoid graft osteolysis after arthroscopic Latarjet procedure

BACKGROUND AND HYPOTHESIS

The Latarjet procedure has been shown to be a reliable method to prevent recurrent anterior shoulder instability. Coracoid bone graft osteolysis is a potential catastrophic complication and can lead to recurrent instability. The purpose of our study is to present a novel quantitative method to measure the amount of coracoid bone osteolysis using 3-dimensional (3D) computed tomography (CT) scan imaging.

MATERIALS AND METHODS

This is a prospective study with 15 patients (16 shoulders) who underwent an arthroscopic Latarjet procedure. Three-dimensional CT scans were obtained at 6 weeks and 6 months. Using volumetric analysis, we quantified the amount of bone loss using our described method. Interobserver reliability and intraobserver reliability were calculated.

RESULTS

On the basis of our new volumetric analysis of the arthroscopic Latarjet procedure using 3D CT scans, we found that the superior half of the coracoid bone graft undergoes a significant amount of osteolysis at 6 months postoperatively. The interobserver reliability and intraobserver reliability were excellent.

DISCUSSION

This study presents a reproducible method to quantify and compare coracoid bone graft osteolysis after an arthroscopic Latarjet procedure. We also developed a description system that may be used for comparison studies. To our knowledge, this is the first method that quantifies the amount of coracoid bone graft osteolysis using more accurate 3D CT scanning.

CONCLUSION

The 3D analysis we propose is a valid method to measure the amount of coracoid bone graft osteolysis after an arthroscopic Latarjet procedure. Our description system may guide the surgeon regarding possible revision surgery when faced with significant osteolysis of the coracoid bone graft.

Biomechanical analysis of the effect of congruence, depth and radius on the stability ratio of a simplistic 'ball-and-socket' joint model

Objectives

The bony shoulder stability ratio (BSSR) allows for quantification of the bony stabilisers in vivo. We aimed to biomechanically validate the BSSR, determine whether joint incongruence affects the stability ratio (SR) of a shoulder model, and determine the correct parameters (glenoid concavity versus humeral head radius) for calculation of the BSSR in vivo.

Methods

Four polyethylene balls (radii: 19.1 mm to 38.1 mm) were used to mould four fitting sockets in four different depths (3.2 mm to 19.1mm). The SR was measured in biomechanical congruent and incongruent experimental series. The experimental SR of a congruent system was compared with the calculated SR based on the BSSR approach. Differences in SR between congruent and incongruent experimental conditions were quantified. Finally, the experimental SR was compared with either calculated SR based on the socket concavity or plastic ball radius.

Results

The experimental SR is comparable with the calculated SR (mean difference 10%, sd 8%; relative values). The experimental incongruence study observed almost no differences (2%, sd 2%). The calculated SR on the basis of the socket concavity radius is superior in predicting the experimental SR (mean difference 10%, sd 9%) compared with the calculated SR based on the plastic ball radius (mean difference 42%, sd 55%).

Conclusion

The present biomechanical investigation confirmed the validity of the BSSR. Incongruence has no significant effect on the SR of a shoulder model. In the event of an incongruent system, the calculation of the BSSR on the basis of the glenoid concavity radius is recommended.

Cite this article: L. Ernstbrunner, J-D. Werthel, T. Hatta, A. R. Thoreson, H. Resch, K-N. An, P. Moroder. Biomechanical analysis of the effect of congruence, depth and radius on the stability ratio of a simplistic ‘ball-and-socket’ joint model. Bone Joint Res 2016;5:453–460. DOI: 10.1302/2046-3758.510.BJR-2016-0078.R1.

Repairing the Capsule to the Transferred Coracoid Preserves External Rotation in the Modified Latarjet Procedure

BACKGROUND

It is not clear whether the anterior capsule should be repaired to the coracoid process or to the native glenoid during the modified Latarjet procedure. We investigated joint stability and range of motion of the shoulder after the modified Latarjet procedure with both of these methods of capsular repair.

METHODS

Eighteen fresh-frozen cadaveric shoulders were used. After a Bankart lesion and 6-mm glenoid defect were created, the coracoid process was transferred to the glenoid and fixed with screws. The anterior capsule was repaired either to the coracoid process (coracoid group) or to the native glenoid (glenoid group). The ranges of internal and external axial rotation were measured with the arm at 0° and 60° of glenohumeral abduction. The range of motion was measured with a constant torque of 200 N-mm. Joint stability was measured using a custom stability testing device. The stability ratio in the anterior-posterior direction was measured with the arm at maximal external rotation and neutral rotation.

RESULTS

The range of external rotation was greater at both 0° and 60° of abduction in the coracoid group compared with the glenoid group (p < 0.05). The range of internal rotation was not significantly different between groups. The end-range stability ratio was not significantly different between groups, but the mid-range stability ratio was significantly greater in the glenoid group.

CONCLUSIONS

Because the difference in the mid-range stability may not be clinically relevant, we recommend repairing the capsule to the coracoid, as that preserves the range of motion in external rotation.

CLINICAL RELEVANCE

Repairing the capsule to the transferred coracoid during the modified Latarjet procedure appears to be beneficial to avoid the limited range of motion in external rotation, but the direct contact of the humeral head and the transferred coracoid might confer a risk of osteoarthritis. Long-term consequences in the clinical setting need to be clarified.

Arthroscopic Implant-Free Bone Grafting for Shoulder Instability With Glenoid Bone Loss: Clinical and Radiological Outcome at a Minimum 2-Year Follow-up

BACKGROUND

Posttraumatic anteroinferior shoulder dislocations with concomitant glenoid bone loss show high recurrence rates. The open J-bone graft technique for implant-less anatomic restoration of bony glenoid structure has previously been described, whereas results of arthroscopic techniques are currently not available.

PURPOSE

To evaluate clinical and radiological outcome after arthroscopic anatomic reconstruction of the glenoid for recurrent anteroinferior glenohumeral instability.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifteen shoulders of 14 patients with recurrent anteroinferior shoulder instability were prospectively followed after glenoid reconstruction with a modified arthroscopic, implant-free J-bone graft. Preoperatively, the instability severity index score was documented. Patients were followed for a minimum of 2 years using the Rowe score and the Constant score. Subjective outcome was assessed using a visual analog scale (VAS) for pain and the subjective shoulder value for sports (SSVS); satisfaction with procedure outcome was also rated. Range of motion was recorded. Incidence of recurrent instability, defined as dislocation, subluxation, or persistent apprehensiveness, was documented. Pre- and postoperative (1 day and 3, 12, and 24 months) computed tomographic images were used to evaluate glenoid bone loss, reconstruction of the glenoid, and graft remodeling.

RESULTS

All preoperative scores (Rowe score: 57.6 ± 14.4; Constant score: 70.9 ± 8.9; VAS: 4.4 ± 2.6; SSVS: 31.4% ± 19.5%) were significantly (P ≤ .02) improved at final follow-up (Rowe score: 98.6 ± 1.5; Constant score: 96.3 ± 3.9; VAS: 0.2 ± 0.6; SSVS: 95.6% ± 3.8%). The preoperative glenoid area (82.1% ± 4.5%) was significantly increased immediately after surgery to 99.2% ± 6.6% (P < .001). After a physiological remodeling process, the glenoid area remained significantly increased at the latest follow-up (89.5 ± 3.2%, P < .001). J-bone grafting successfully restored glenoid concavity by significantly increasing concavity extent and depth from preoperative (19.8 ± 2.1 and 0.9 ± 0.6 mm, respectively) to postoperative (24.0 ± 2.1 and 2.1 ± 0.8 mm, respectively) (P < .001). There were no recurrent instabilities. One traumatic graft fracture occurred during the follow-up period.

CONCLUSION

The arthroscopic J-bone graft technique permits minimally invasive reconstruction of anteroinferior glenoid defects and provided excellent early clinical outcome without recurrent instability in posttraumatic shoulder dislocations. A physiological remodeling process leads to restoration of a more natural glenoid anatomy.

Glenohumeral translation in ABER position during muscle activity in patients treated with Latarjet procedure: an in vivo MRI study

PURPOSE

The Latarjet procedure is frequently performed when treating traumatic anteroinferior shoulder instability. This procedure is supposed to have a triple effect: osseous, muscular and ligamentous. The main stabilizing mechanism in cadaver studies on fresh-frozen shoulders seems to be the sling effect produced by the subscapularis and the conjoint tendon. It has been hypothesized that muscle contraction in ABER position (abduction-external rotation) is able to translate the humeral head posteriorly and superiorly due to the sling effect. The aim of this study was to analyse the humeral head translation relative to the glenoid with the arm in ABER position with and without muscle contraction.

METHODS

Twenty-one subjects divided into two groups (Group A: after Latarjet; Group B: healthy subjects) were examined with an open MRI system with the shoulder in abduction-external rotation (ABER) position to analyse humeral head translation during muscle activity.

RESULTS

In normal shoulders, there was no significant difference in anteroposterior or superoinferior translation between the rest position and the muscle-activated state. In subjects after the Latarjet procedure, the difference was significant and was also significant between both groups of subjects for posterior translation, but not for superior translation.

CONCLUSION

In patients treated with Latarjet procedure, there are significant changes in glenohumeral translation during muscular activity when in ABER position, with the humeral head going more posteriorly, in comparison with normal shoulders. This study confirms the stabilizing sling effect of the transposed conjoint tendon in the ABER position.

LEVEL OF EVIDENCE

Retrospective case-control study, Level III.

Technical guide and tips on the all-arthroscopic Latarjet procedure

Shoulder dislocation and subsequent anterior instability is a common problem in young athletes. The arthroscopic Bankart repair was originally described by Morgan et al. in 1987. The procedure has benefited from many technical advancements over the past 25 years and currently remains the most commonly utilized procedure in the treatment of anterior glenohumeral instability without glenoid bone loss. Capsulolabral repair alone may not be sufficient for treatment of patients with poor capsular tissue quality and significant bony defects. In the presence of chronic anterior glenoid bony defects, a bony reconstruction should be considered. The treatment of anterior shoulder instability with transfer of the coracoid and attached conjoint tendon such as the Latarjet procedure has provided reliable results. The arthroscopic Latarjet procedure was described in 2007 by the senior author, who has now performed the procedure over 450 times. The initial surgical technique has evolved considerably since its introduction, and this article presents a comprehensive update on this demanding but well-defined procedure. This article reviews technical tips to help the surgeon perform the surgery more smoothly, navigate through challenging situations, and avoid potential complications. Level of evidence V.

Comparison of arthroscopic and open Latarjet with a learning curve analysis

PURPOSE

To compare arthroscopic and open Latarjet performed by a single shoulder surgeon with learning curve analysis

METHODS

A comparative and learning curve analysis was carried out on a prospectively gathered database of 2 consecutive series of patients treated with arthroscopic and open Latarjet procedures performed by a single shoulder surgeon between 2008 and 2014. The database included patient characteristics, ISIS scores, operative time, intra- and postoperative complications, graft and screws positioning, as well as pre- and postoperative Walch-Duplay scores.

RESULTS

Sixty-four patients were included in the study, 28 in the arthroscopic group and 36 in the open group with similar age, sex ratio and preoperative ISIS score. Operative time was significantly higher in the arthroscopic group (146 versus 81 min, p = 0.001), and although no intra-operative complications were recorded in either group, there were significantly more postoperative complications in the arthroscopic group (29 vs. 11 %, p = 0.03). Screw placement was more accurate in the open group, and postoperative Walch-Duplay score did not show any significant difference between the groups (88 points in the arthroscopic group and 91 points in the open group). The arthroscopic Latarjet learning curve analysis showed that the need for conversion ceased after the first 10 patients and that surgical time came close to that of open procedure after 20 procedures.

CONCLUSIONS

In this study, 10 arthroscopic Latarjet procedures were needed to overcome the need for conversion, and 20 procedures to achieve equal operating time to the open technique. Even though functional outcome and patient satisfaction were similar in both techniques, complications, screw placement inaccuracy, persistent apprehension and recurrences still remain higher with the arthroscopic technique.

LEVEL OF EVIDENCE

Retrospective comparative analysis, Level III.

Mid-range shoulder instability modeled as a cam-follower mechanism

In this paper, we model a simplified glenohumeral joint as a cam-follower mechanism during experimental simulated dislocation. Thus, humeral head trajectory and translational forces are predicted using only contact surface geometry and compressive forces as function inputs. We demonstrate this new interpretation of glenohumeral stability and verify the accuracy of the method by physically testing a custom-molded, idealized shoulder model and comparing data to the output of the 2D mathematical model. Comparison of translational forces between experimental and mathematical approaches resulted in r(2) of 0.88 and 0.90 for the small and large humeral head sizes, respectively. Comparison of the lateral displacement resulted in r(2) of 0.99 and 0.98 for the small and larger humeral head sizes, respectively. Comparing translational forces between experiments and the mathematical model when varying the compressive force to 30 N, 60 N, and 90 N resulted in r(2) of 0.90, 0.82, and 0.89, respectively. The preliminary success of this study is motivation to introduce the effects of soft tissue such as cartilage and validation with a cadaver model. The use of simple mathematical models such as this aid in the set-up and understanding of experiments in stability research and avoid unnecessary depletion of cadaveric resources.

Lateral Decubitus All-Arthroscopic Latarjet Procedure for Treatment of Shoulder Instability

Shoulder instability can be a challenging condition to treat when it becomes refractory to soft-tissue procedures or when bone loss exceeds 25% to 27% of the glenoid. The Bristow-Latarjet procedure has been developed and popularized to deal with these concerns. Traditionally, the procedure has been performed as an open approach; however, this has been recently supplanted by novel arthroscopic techniques. We present a technique for the procedure performed with the patient in a semi-lateral decubitus position that assists with optimal graft placement on the native glenoid. We use the cannulated Bristow-Latarjet Instability Shoulder System (DePuy Mitek, Raynham, MA). After a diagnostic arthroscopic evaluation, we use multiple arthroscopic anterior portals to debride the rim of the glenoid. The coracoid is prepared and taken down arthroscopically, and the cannulated guide is attached and advanced through an arthroscopically created subscapularis split. With the shoulder held in a reduced position, we are then able to drill and anchor the graft to the native glenoid. The patient is able to begin gentle range-of-motion exercises immediately postoperatively.

Arthroscopic Latarjet and Capsular Shift (ALCS) procedure: a new "freehand" technique for anterior shoulder instability associated with significant bone defects

Anterior shoulder instability associated with significant bone loss has been described as "bony-instability," and this condition is usually treated with an anterior glenoid bone grafting procedure (Latarjet procedure). The Latarjet procedure involves transfer of the horizontal limb of the coracoid process along with the conjoint tendon to the anterior glenoid rim, and is traditionally performed as an open surgical procedure. Recently, an arthroscopic technique for the Latarjet procedure has been described; the technique necessitates the use of specialized instrumentation and involves excision of the entire anterior capsule to facilitate coracoid fixation. We describe a new "freehand" arthroscopic technique for the Latarjet procedure, and, in addition, a simultaneous capsular shift to further optimize mid and end range stability. This technique eliminates the use of additional instrumentation and can be done using routine arthroscopic instruments. Preliminary experience with this technique suggests that the arthroscopic Latarjet and capsular shift is a technically demanding procedure. Glenohumeral capsule can be preserved, and this should be attempted wherever possible to optimize stability. Additional specialized instrumentation would probably reduce surgical time; however, the procedure can be performed with routine instruments.

Biomechanics of complex shoulder instability

Identification and treatment of the osseous lesions associated with complex shoulder instability remains challenging. Further biomechanical testing is required to delineate critical defect values and determine which treatments provide improved glenohumeral joint stability for the various defect sizes, while minimizing the associated complications.