Biomechanical evaluation of a simulated Bankart lesion

Single- and Double-Loaded All-Suture Anchor Repairs of Anteroinferior Labral Tears Are Biomechanically Similar in a Cadaveric Shoulder Model

Purpose

To compare the biomechanical strength of single- versus double-loaded all-suture constructs in an anteroinferior glenoid labral repair.

Methods

Anteroinferior labral lesions were created on 6 matched pairs of cadaveric shoulder specimens. Each shoulder in a matched pair was randomized to either receive capsulolabral repair with 3 single-loaded all-suture anchors or 3 double-loaded all-suture anchors. Immediately following capsulolabral repair, the specimens underwent mechanical testing, which included cyclic testing (5 N to 50 N for 500 cycles) and load-to-failure testing (rate of 15 mm/min). The gap formation between the repaired labrum and glenoid (measured at 1, 25, 100, and 500 cycles), the load at 2-mm gap formation, the maximum load at failure and the method of failure were recorded. Data were analyzed with paired Student t tests and Bonferroni correction factor.

Results

The single and double all-suture constructs did not differ significantly in gap formation at any number of cycles, load to 2-mm gap formation (P = .75), or maximum load to failure (P = .46) between the 2 groups.

Conclusions

In this study, single-loaded and double-loaded all-suture anchor constructs demonstrated comparable biomechanical performance and did not significantly differ in gap formation, load to 2-mm gap formation, or maximum load to failure when used in the capsulolabral repair of anteroinferior glenoid labral tears in human cadaveric specimens.

Clinical Relevance

Although studies have evaluated the biomechanical properties of various arthroscopic labral stabilization techniques, the biomechanical properties of all-suture anchors with regard to labral stabilization are not well understood.

Anatomical, functional and biomechanical review of the glenoid labrum

The glenohumeral joint is the most mobile joint in the human skeleton, supported by both active and passive stabilisers. As one of the passive stabilisers, the glenoid labrum has increasingly been recognised to play an important role in stability of the glenohumeral joint, acting to maintain intraarticular pressure, centralise the humeral head and contribute to concavity-compression stability. Several studies have investigated the macro- and micro-anatomical features of the labrum as well as its biomechanical function. However, in order to better understand the role of the labrum and its mechanics, a comprehensive anatomical, functional and biomechanical review of these studies is needed. Therefore, this article reviews the current literature detailing anatomical descriptions of the glenoid labrum, with an emphasis on its function(s) and biomechanics, as well as its interaction with neighbouring structures. The intimate relationship between the labrum and the surrounding structures was found to be important in glenohumeral stability, which owes further investigation into the microanatomy of labrum to better understand this relationship.

Glenoid Labral Injuries Are More Common Posteriorly Than Superiorly and Are Combined Across Multiple Areas of the Glenoid

Purpose

To categorize arthroscopically observed labral injuries to include location on the glenoid and frequency of the injuries in each location.

Methods

Patients undergoing arthroscopic labral surgery between January 2018 and June 2020 were reviewed. Inclusion criteria for labral injury were consistently applied and included history, clinical examination and imaging findings, and failure of rehabilitation. Exclusion criteria included arthritis, adhesive capsulitis, and previous surgery. Injury locations were categorized into superior, anterior, and/or posterior areas on the glenoid and as isolated in one area or combined in more than one area. Injury patterns also were evaluated. Interrater and intrarater agreement was assessed between 2 raters for injury location and tear pattern for 22 randomly assigned cases.

Results

In total, 167 cases met the inclusion criteria. Injuries were found in all areas. Combined injuries were found almost twice as often as isolated injuries (63.5% vs 37.5%). Isolated posterior injuries had the greatest frequency of all specific injury types (26.3%). Isolated superior injuries (SLAP 2-4) had a frequency of 7.2%. Tear patterns included peel back, separation/split, insubstance injury, peripheral rim flattening, and extension into the posterior inferior glenohumeral ligament. Interrater was excellent for all tear locations (intraclass correlation coefficient ≥0.85) whereas intrarater agreement was good to excellent (intraclass correlation coefficient ≥0.63).

Conclusions

Labral injuries that are associated with clinical symptoms can occur as isolated or combined types in the superior, anterior, and posterior glenoid areas and can display multiple injury patterns. Combined types of injuries are almost twice as common as those that are isolated in one area. Posterior injuries, isolated or combined, are frequent but superior injuries are less common

Level of Evidence

Level IV, therapeutic case series.

Posterior Labral Tear Extension Concomitant With Shoulder Bankart Injuries Is not Uncommon

Purpose

To identify the rate and risk factors of posterior labral involvement in operatively managed Bankart lesions and assess the effectiveness of MRI arthrogram for preoperative identification of such injury patterns.

Methods

A consecutive cohort of patients undergoing arthroscopic Bankart repair were retrospectively reviewed. All subjects underwent a prearthroscopy MRI arthrogram. Operative findings were used as the gold standard for posterior labral tear extension. Patient demographic and surgical data were then analyzed to identify independent factors associated with the presence of concomitant posterior labral injury.

Results

Of 124 patients undergoing arthroscopic Bankart stabilization, 23 (19%) were noted to demonstrate posterior labral injury on arthroscopic evaluation. Factors associated with injury to the posterior labrum included those sustaining two or fewer dislocations events (P =.001), an earlier average presentation (P = .001), and a reported “contact” mechanism of dislocation (P = .02). Posterior labral involvement did not correlate with surgical positioning (beach-chair versus lateral) or the need for revision surgery. On the basis of review of preoperative imaging, MRI arthrogram demonstrated a sensitivity of 83% and a specificity of 95% for detection of posterior labral injury.

Conclusions

Posterior propagation of Bankart lesions is relatively common following shoulder dislocations, with a rate of 18.5%. Risk factors for posterior labral extension include two or fewer dislocations, early presentation from the time of injury, and contact sports. On the basis of these findings, careful assessment of the posterior labrum on MRI arthrogram may reveal the majority, but not all, of these lesions.

Level of Evidence

Level III, retrospective case-controlled study.

Influential and Highest Cited Shoulder Instability Articles: A Bibliometric Analysis

Background

In orthopaedic surgery and other fields, the effect of influential journal articles has been evaluated by their citation counts and their correlation with methodological quality.

Purpose

To identify and characterize the 50 most cited articles on shoulder instability, examine trends in publication characteristics, and evaluate the correlation of citations with quality of evidence.

Study Design

Cross-sectional study.

Methods

The Web of Science and Scopus online databases were searched to identify the top 50 most cited articles on shoulder instability, based on the average number of citations from each database. Article characteristics were recorded, and level of evidence and methodological quality were assessed using the modified Coleman Methodology Score (mCMS), Jadad scale, and Methodological Index for Non-Randomized Studies (MINORS). Spearman correlation was used to evaluate relationships between citations or citation density (citations/y) and level of evidence or methodological scoring. Top cited articles from recent years were also aggregated.

Results

The top 50 most cited papers had a mean ± SD number of citations of 381.5 ± 166.7, with a mean of 15.0 ± 8.8 citations/y. Overall, 15 articles (30%) were biomechanical/cadaveric studies, and 15 (30%) were case series. Only 3 (6%) were considered to have level 1 evidence. The mean ± SD mCMS was 54.4 ± 12.7, mean ± SD Jadad score was 3.1 ± 1.4, and mean ± SD MINORS score was 10.5 ± 3.3. There were no significant correlations between citation rank or density and methodological assessments. There were weak correlations between citation rank and publication year (r _s = 0.32; P = .022) and between rank and level of evidence (r _s = -0.38; P = .047). The correlation between citation density and publication year was moderate (r _s = 0.70; P < .0001). There was no difference in citation density of the top 10 articles from 2010 to 2020 compared with the top 10 from the overall list (23.8 ± 5.3 vs 28.8 ± 9.5; P = .16).

Conclusion

Influential articles in shoulder instability included a high proportion of biomechanical/cadaveric studies. The majority of top cited articles had lower evidence levels and poorer methodological quality without strong correlation with citations or citation density. There was a moderate correlation between citation density and year of publication.

Location and magnitude of capsular injuries varies following multiple anterior dislocations of the shoulder: Implications for surgical repair

Capsular injuries can occur during multiple shoulder dislocations. The purpose of this study is to evaluate the location and magnitude of glenohumeral capsular injury following multiple dislocations. We hypothesized that the magnitude of capsular injury would increase and the location of peak injury would vary depending on the number of dislocations. Seven fresh-frozen cadaveric shoulders were used. A 7 × 11 grid of strain markers was affixed to the anteroinferior capsule. Each joint was then mounted to a six degree-freedom robotic testing system. Marker tracking was performed following 1, 2, 3, 4, 5, and 10 dislocations to determine the nonrecoverable strain as capsular injury. Following each dislocation, the magnitude of the maximum principal strain representing the nonrecoverable strain in the inferior glenohumeral capsule was quantified by comparing the strain marker positions following each dislocation. The peak value of nonrecoverable strain statistically increased with the number of dislocations in five of seven specimens (p = .0007). The capsular location that had the peak value of nonrecoverable strain varied according to the number of dislocations, and from specimen to specimen. The nonrecoverable strain was identified in the posterior capsule and anterior axillary pouch, which increased with the number of dislocations compared to the other regions of the capsule (p = .001-.012) by up to 16%. Clinical significance: While plication of the anterior axillary pouch is important following multiple dislocations, a more extensive anterior capsular shift may be necessary with an increased number of dislocations in addition to a posterior capsular shift when appropriate.

Arthroscopic Bankart repair with an individualized capsular shift restores physiological capsular volume in patients with anterior shoulder instability

PURPOSE

Capsular volume reduction in the context of anterior arthroscopic shoulder stabilization represents an important but uncontrolled parameter. The aim of this study was to analyse capsular volume reduction by arthroscopic Bankart repair with an individualized capsular shift in patients with and without ligamentous hyperlaxity compared to a control group.

METHODS

In the context of a prospective controlled study, intraoperative capsular volume measurements were performed in 32 patients with anterior shoulder instability before and after arthroscopic Bankart repair with an individualized capsular shift. The results were compared to those of a control group of 50 patients without instability. Physiological shoulder joint volumes were calculated and correlated with biometric parameters (sex, age, height, weight and BMI).

RESULTS

Patients with anterior shoulder instability showed a mean preinterventional capsular volume of 35.6 ± 10.6 mL, which was found to be significantly reduced to 19.3 ± 5.4 mL following arthroscopic Bankart repair with an individualized capsular shift (relative capsular volume reduction: 45.9 ± 21.9%; P < 0.01). Pre-interventional volumes were significantly greater in hyperlax than in non-hyperlax patients, while post-interventional volumes did not differ significantly. The average shoulder joint volume of the control group was 21.1 ± 7.0 mL, which was significantly correlated with sex, height and weight (P < 0.01). Postinterventional capsular volumes did not significantly differ from those of the controls (n.s.).

CONCLUSION

Arthroscopic Bankart repair with an individualized capsular shift enabled the restoration of physiological capsular volume conditions in hyperlax and non-hyperlax patients with anterior shoulder instability. Current findings allow for individual adjustment and intraoperative control of capsular volume reduction to avoid over- or under correction of the shoulder joint volume. Future clinical studies should evaluate, whether individualized approaches to arthroscopic shoulder stabilization are associated with superior clinical outcome.

Arthroscopic Bankart repair: A matched cohort comparison of the modified Mason Allen method and the simple stitch method

INTRODUCTION

Arthroscopic Bankart repair (ABR) has become a standard treatment for recurrent anterior shoulder dislocation in cases with minimal bone loss. Using the standard Bankart repair technique, the failure rate has been reported to be approximately between 4 and 35%. In addition to the original injury, multiple pathologies can occur after a dislocation including a Bankart lesion, capsular redundancy and bone defects. In cases with no significant bone loss, soft tissue plays a major role in stabilizing the shoulder joint. We hypothesized that effective repair of soft tissue with good inferior capsular shifting and proper capsulolabral restoration can create a proper level of soft tissue tension so the horizontal mattress suture method should improve outcomes.

MATERIALS AND METHODS

A retrospective cohort study was conducted by reviewing the records of patients with recurrent anterior instability who underwent ABR at a single institution between January 2009 and December 2017. Demographic information, preoperative radiographic data including glenoid bone loss, Hill-Sachs width, glenoid track and other surgical details were retrieved from the medical records. The patients identified were divided into 2 groups. Group 1 had one modified Mason Allen stitch plus simple stitches, while Group 2 had only simple stitches. Data obtained from the patient included failure rate, patient satisfaction, the ROWE score and Walch-Duplay score at a minimum of 2 years after surgery. Risk factors for failure were also identified.

RESULTS

Group 1 included 50 patients (mean age 27.2 ± 9.4 years) who underwent modified Mason Allen stitch ABR (median follow-up, 59.2 months; range, 26.2-128.6 months). Group 2 included 30 patients (mean age 26.9 ± 8.5 years) who underwent simple stitch repair ABR (median follow-up, 68.0 months; range, 24.0-127.9 months). All patients met the inclusion criteria. Evaluation at the final follow-up compared Group 1 and Group 2: ROWE score (86.8 vs 76.3, P = 0.001), Walch-Duplay score (87.2 vs 82.0, P = 0.035), respectively. Failure rates were 6% in group 1 compared to 10% in group 2 (P = 0.511).

CONCLUSIONS

The modified Mason Allen stitch technique and the simple stitches technique ABR both result in excellent patient satisfaction at a minimum 2-year follow-up. Both techniques successfully restore shoulder stability, but the modified Mason Allen stitch technique results in better functional outcomes.

STUDY DESIGN

Cohort study; level of evidence, 3.

Influence of Glenoid Labral Bumper Height and Capsular Volume on Clinical Outcomes After Arthroscopic Bankart Repair as Assessed With Serial CT Arthrogram: Can Anterior-Inferior Volume Fraction Be a Prognostic Factor?

BACKGROUND

Arthroscopic labral repair combined with capsular plication decreases joint volume and restores glenoid labral bumper height; thus, the procedure helps decrease capsular redundancy. However, the decreased volume and restored glenoid labral bumper height could change over time, which could influence the outcome of the operation.

PURPOSE

To (1) measure glenoid labral bumper height and capsular volume quantitatively in serial computed tomography arthrography (CTA) and evaluate the relationship between bumper height and joint volume and (2) compare the difference in bumper height and joint volume between groups with and without apprehension after arthroscopic Bankart repair.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Patients who had undergone arthroscopic Bankart repair between January 2012 and June 2016, and were assessed by CTA 3 to 6 months and 12 to 18 months after the operation were included. An image reconstruction program (3-dimensional slicer) was used to calculate inferior, anterior-inferior, and posterior-inferior joint volumes; the ratio of the anterior-inferior volume to the inferior volume was defined as the anterior-inferior volume fraction (VF_AI). We also measured glenoid labral bumper height at the 5-, 4-, and 3-o'clock positions.

RESULTS

A total of 50 patients were enrolled as study participants (mean age, 25.2 ± 9.29 years). Of these, 10 patients had either redislocation or apprehension, and 40 patients had neither. A significant correlation was observed between 5-o'clock glenoid labral bumper height and VF_AI on early CTA (3-6 months) and late CTA (12-18 months) (early CTA: Pearson coefficient, -0.335, P = .040; late CTA: Pearson coefficient, -0.468, P = .003). VF_AI at the early CTA was 42.20 ± 10.15 in the group with apprehension and 33.49 ± 9.66 in the group without apprehension; a significant difference was observed. VF_AI at the late CTA was 45.84 ± 11.97 in the group with apprehension and 37.65 ± 9.70 in the group without apprehension and thus showed a significant difference between the 2 groups. However, the 3-, 4-, and 5-o'clock glenoid labral bumper heights on early and late CTAs did not show a statistically significant difference between the 2 groups.

CONCLUSION

Early postoperative VF_AI is related to postoperative apprehension and redislocation and might be reduced by increasing the 5-o'clock glenoid labral bumper height.

Arthroscopic Bankart repair following traumatic recurrent shoulder dislocation: A prospective review of 30 cases

BACKGROUND

Literature on outcomes of arthroscopic Bankart repair at the intervening time intervals in traumatic recurrent dislocation of shoulder joint is limited.

STUDY DESIGN

Case series.

SUBJECTS AND METHODS

A prospective review of 30 shoulders, aged 20-40 years with clinically and magnetic resonance imaging established findings that were treated with primary arthroscopic Bankart repair and followed up for a minimum of 2 years. Outcomes were evaluated using Rowe score and University of California at Los Angeles (UCLA) scoring system.

RESULTS

The mean age was 26.40 years. All patients had definite trauma history. Average number of dislocation was 13.77 + 18.435 (range: 3-100). Time duration from first dislocation to surgery was an average of 4.80 + 3.576 years. The average size of the lesion was approximately 31% of the glenoid circumference. The number of suture anchors used for fixation did not correlate significantly with any of the scores. The mean Rowe and UCLA scores were 94.16 ± 9.7 and 33.83 ± 3.32, respectively, at final follow-up. The average duration of hospital stay was 7 days. Of the 30 patients, 2 (6.66%) had dislocation events post-operatively. Returns to pre-injury level were available for 27 (90%) of 30 patients. Multivariate analysis of independent Variables: age; side and number of dislocations, time to surgery, duration of surgery, size of lesion, number of anchors, and concurrent Hill-Sachs lesion, shown to have no significant relationship to outcomes.

CONCLUSION

Arthroscopic Bankart repair is an effective and safe technique for treating anterior glenohumeral instability in patients with recurrent traumatic shoulder dislocation.

Modified Putti-Platt procedure for recurrent anterior shoulder instability

PURPOSE

The classic Putti-Platt technique was modified by suturing the lateral subscapularis tendon to the capsule instead of the anterior glenoid edge. We report the clinical results of a modified Putti-Platt procedure in patients with traumatic anterior shoulder instability.

METHODS

The study reports results in 434 patients (450 shoulders) with traumatic anterior shoulder instability. The patients comprised 322 men and 122 women with a mean age of 22 years. Clinical results were evaluated by the Rowe score, Japan Shoulder Society Shoulder Instability Score (JSS-SIS); recurrence of instability, instability severity index score (ISIS), restriction of external rotation, return to sports activities, and osteoarthritis on plain radiographs and MRI were examined.

RESULTS

The mean Rowe score improved from 26 to 90 points, and the mean JSS-SIS improved from 51 to 88 points. Altogether, 419 patients (97%) had no recurrence at a minimum of two years of follow-up, even though the study included 87 patients with an ISIS of ≥ 7 points. External rotation was limited at 6 months, and 33 of 228 patients (14%) could not return to the same level of sports activities. Among 44 patients at the follow-up extending to ten to 27 years, external rotation was still limited but no plain radiography showed osteoarthritis more than stage 2.

CONCLUSION

This modified Putti-Platt procedure was not appropriate for throwing athletes but could be a surgical option for patients with high risk of recurrence.

Altered shoulder kinematics using a new model for multiple dislocations-induced Bankart lesions

BACKGROUND

Many active individuals undergo multiple dislocations during the course of a season before surgical treatment without considering the implications of each successive injury. Therefore, the purpose of this study was to develop a multiple dislocation model for the glenohumeral joint and evaluate the resulting changes in joint function.

METHODS

Eight cadaveric shoulders were evaluated using a robotic testing system. A simulated clinical exam was performed by applying a 50 N anterior load to the humerus at 60° of glenohumeral abduction and external rotation. Each joint was then dislocated. The same loads were applied again and the resulting kinematics were recorded following each of 10 dislocations. The force required to achieve dislocation was recorded and capsulolabral status was assessed.

FINDINGS

A reproducible Bankart lesion was repeatedly created following the dislocation protocol. The force required for all dislocations significantly decreased following the 1st dislocation. In addition, even lower forces were required to achieve the 5th and subsequent dislocations (p < 0.05). Anterior translation in response to an anterior load during the simulated clinical exam increased between the intact and injured joints (p < 0.05). However, anterior translation reached a plateau following the 3rd to 10th dislocations and was increased compared with the 1st dislocation (p < 0.05).

INTERPRETATION

A repeatable Bankart lesion was not surgically made, but created by our new dislocation model. Joint function appeared to reach a constant level after the 3rd to 5th dislocations. Thus, multiple dislocations result in a deleterious dose dependent effect suggesting additional damage is not sustained after the fifth dislocation.

LEVEL OF EVIDENCE

Controlled laboratory study.

The effect of shoulder position on inferior glenohumeral mobilization

STUDY DESIGN

Cross-sectional clinical measurement study.

INTRODUCTION

Inferior mobilizations are used to treat patients with shoulder dysfunctions. Common positions recommended for promoting an inferior glide include: (1) an open-packed position (OPP) in which the shoulder is in 55° of abduction, 30° of horizontal adduction, and no rotation; (2) neutral position (NP) of the shoulder; and (3) position of 90° of shoulder abduction (ABDP). Studies comparing the impact of position on inferior mobilization are lacking.

PURPOSE OF THE STUDY

To determine the effect of shoulder position on humeral movement and mobilization force during inferior mobilizations.

METHODS

Twenty-three subjects were tested bilaterally. Subjects were placed in the OPP, and an ultrasound transducer placed over the superior glenohumeral joint. As inferior mobilization forces were applied through a dynamometer, ultrasound images were taken at rest and during 3 grades of inferior mobilization. This process was repeated in the NP and the ABDP.

RESULTS

In the NP, movements during grade 1, 2, and 3 mobilizations were 1.8, 3.8, and 4.5 mm, respectively. Movements measured in the OPP (1.0, 2.4, and 3.6 mm, respectively) and in the ABDP (1.0, 2.2, and 2.3 mm, respectively) were less. Forces were higher in the NP during grade 1, 2, and 3 mobilizations (51.8, 138.7, and 202.1 N, respectively) than in the OPP (37.2, 91.2, and 139.9 N, respectively) and the ABPD (42.5, 115.3, and 165.5 N, respectively).

DISCUSSION

Mobilization position altered the movement and force during inferior mobilizations.

CONCLUSIONS

Shoulder position should be considered when utilizing inferior mobilizations.

LEVEL OF EVIDENCE

NA.

Comparison of Curved and Straight Anchor Insertion for Bankart Repair

The quality of Bankart repair may be compromised by the presence of glenoid perforation during suture anchor placement. The purpose of this study was to compare the rate of glenoid perforation and biomechanical strength of antero-inferior suture anchors placed with a curved vs a traditional straight technique through an anteroinferior portal. Ten bilateral pairs of fresh human cadaveric shoulders were randomized to either a curved or a straight suture anchor insertion technique. An anteroinferior portal was used to place a 1.5-mm soft anchor in the anteroinferior glenoid (5:30 position for right shoulders). Anatomic dissection was performed, and the maximum load of each anchor was measured using a materials testing system. The overall rate of glenoid perforation by the anteroinferior anchor was 50%. The rate of glenoid perforation was 40% in the straight group and 60% in the curved group (P=.41). The median maximum load was 86 N in the straight group and 137 N in the curved group (P=.23). The median maximum load of the anchors that did perforate the glenoid was 102 N and of those that did not was 118 N (P=.72). The mode of failure was suture anchor pullout in all except one specimen. The curved guide was not superior to the traditional straight guide in terms of the rate of glenoid perforation or the maximum load of the suture anchors. Anterior cortical perforation of the glenoid during anteroinferior suture anchor placement is common with both techniques. [Orthopedics. 2019; 42(2):e242-e246.].

Meta-Analysis of Randomized Controlled Trials Involving Anterior Shoulder Instability

Background:

Arthroscopic repair is gaining popularity over open repair for the treatment of bankart lesions. The study aims to evaluate the outcome of arthroscopic repair with open repair in randomised controlled trials conducted comparing the two techniques.

Methods:

We searched the Cochrane library, PubMed and EMBASE up to December 2017 for clinical trials comparing the outcomes of arthroscopic bankart repair with open bankart repair. We used fixed or random effects model depending upon heterogenicity. Dichotomous variables were presented as Risk Ratios (RRs) with 95% Confidence Intervals (CIs), and continuous data were measured as measured differences with 95% CIs.

Result:

Five studies were included, with sample size ranging from 42 to 196. Fixed effect analysis showed that the shoulder was more stable in open repair (RR=0.897, 95% CI: 0.821 to 0.980, P= 0.94) but the loss of external rotation at shoulder joint was also higher in those had open repair (RR=0.325, SMD=-0.411, 95% CI: -1.229 to 0.407). The functional outcome assessed by Rowe score was better in open repair (P=0.325). The operative time was lesser in arthroscopic repair but was not statistically significant (P=0.085).

Conclusion:

Our meta-analysis showed that the use of arthroscopic repair though offers better shoulder movement but the open repair is superior in terms of shoulder stability.

Normal Range of Humeral Head Positioning on the Glenoid on Magnetic Resonance Imaging: Validation through Comparison of Computed Tomography and Magnetic Resonance Imaging

Background

To determine the normal range of humeral head positioning on magnetic resonance imaging (MRI).

Methods

We selected normal subjects (64 patients; group A) to study the normal range of humeral head positioning on the glenoid by MRI measurements. To compare the MRI measurement method with the computed tomography (CT), we selected group B (70 patients) who underwent both MRI and CT. We measured the humeral-scapular alignment (HSA) and the humeral-glenoid alignment (HGA).

Results

The HSA in the control group was 1.47 ± 1.05 mm, and the HGA with and without reconstruction were 1.15 ± 0.65 mm and 1.03 ± 0.59 mm, respectively, on MRI. In the test group, HSA was 2.67 ± 1.47 mm and HGA with and without reconstruction was 1.58 ± 1.16 mm and 1.49 ± 1.08 mm, on MRI. On CT, the HSA was 1.72 ± 1.01 mm, and HGA with and without reconstruction were 1.54 ± 0.96 mm and 1.59 ± 0.93 mm, respectively. HSA was significantly different according to image modality (p=0.0006), but HGA was not significantly different regardless of reconstruction (p=0.8836 and 0.9234).

Conclusions

Although additional CT scans can be taken to measure decentering in patients with rotator cuff tears, reliable measurements can be obtained with MRI alone. When using MRI, it is better to use HGA, which is a more reliable measurement value based on the comparison with CT measurement (study design: Study of Diagnostic Test; Level of evidence II).

Traumatic Anterior Instability: Treatment Options for Initial Instability

Because of the lack of bony restraints and minimal articular contact, the glenohumeral joint can attain significant range of motion; however, this results in the propensity for instability. The most generic form of instability, traumatic anterior instability, reliably produces a series of pathoanatomic findings. While reliable, these findings contribute to the complexities of caring for patients after an initial instability event. Numerous studies have examined this issue and determined that careful consideration of patient factors can guide successful treatment, whether it be surgical or nonsurgical, after initial instability. Such forms of treatment have shown to provide a good functional outcome and decreases morbidity. To be able to provide successful treatment requires a thorough understanding of the pathoanatomic of an instability event and the intricacies of the evaluation of a patient after an initial instability event.

Multidirectional Instability of the Shoulder: Treatment Options and Considerations

Multidirectional instability (MDI) is a debilitating condition that involves chronic subluxation or dislocation of the shoulder in >1 direction. Numerous proposed mechanisms of MDI exist, which occurs in the setting of redundant capsular tissue. Symptoms can range from recurrent dislocations or subluxations to vague aching pain that disrupts activities of daily living. Magnetic resonance imaging is often performed during evaluation of this condition, although magnetic resonance arthrography may provide more detailed images of the patulous capsule. In the absence of a well-defined traumatic cause, such as a labral tear, initial treatment for MDI is a structured rehabilitation program with exercises aimed at strengthening the rotator cuff and periscapular muscles to improve scapular kinematics. Patients with recalcitrant symptoms may benefit from surgical stabilization, including open capsular shift or arthroscopic capsular plication, aimed at decreasing capsular volume and improving stability.

Anatomic analysis of the whole articular capsule of the shoulder joint, with reference to the capsular attachment and thickness

Background

Although conventional Bankart repair has been the accepted procedure for traumatic anterior glenohumeral instability, the humeral avulsion of the glenohumeral ligament or an elongation of the capsule remains challenging to decide the appropriate treatment. The anatomical knowledge regarding the whole capsule of glenohumeral joint is necessary to accurately treat for the capsular disorders. The aims of the current study were to investigate the anatomical features of capsular attachment and thickness in a whole capsule of glenohumeral joint.

Methods

We used 13 shoulders in the current study. In 9 shoulders, we macroscopically measured the attachment widths of the capsulolabrum complex on the scapular glenoid, and the attachment widths of the capsule on the humerus in reference to the scapular origin of the long head of triceps brachii, and the humeral insertion of the rotator cuff tendons. We additionally used 4 cadaveric shoulders, which were embalmed using Thiel’s method, for the analysis of the thickness in a whole capsule by using micro-CT.

Results

The glenoidal attachment of the articular capsule appeared to have a consistent width except for the superior part of the origin of the long head of triceps brachii. On the humerus, the articular capsule was widely attached to areas without overlying rotator cuffs, with the widest width (17.3 ± 0.9 mm) attached to the axillary pouch. The inferior part of the capsule, which was consistently thicker than the superior part, continued to the superior part along the glenoid and humeral side edge.

Conclusions

The current study showed that the inferior part of the glenohumeral capsule had a wide humeral attachment from the inferior edge of the subscapularis insertion to the inferior edge of the teres minor insertion via the anatomical neck of the humerus, and the thickness of it was thicker than the superior part of the capsule.

Mid-term to long-term outcome of the open Bankart repair for recurrent traumatic anterior dislocation of the shoulder

BACKGROUND

The purpose of this study was to assess the long-term outcome of the open Bankart repair for traumatic, recurrent anterior dislocation of the shoulder by evaluation of recurrence, range of motion, return to sports, arthritis, patient satisfaction, and outcome measures.

METHODS

Of 162 patients, 127 patients (mean age, 31 years) were evaluated at a mean follow-up of 17.1 years (5-24) after undergoing an open Bankart repair using suture anchors. An independent orthopedic surgeon obtained a history and examined each for range of motion. Radiographs for arthritis and osteolysis were obtained unless the patient refused. Questionnaires including return to sports and function as well as satisfaction and outcome measures were completed by all patients.

RESULTS

There was 1 recurrent dislocation (0.8%) and 1 recurrent subluxation (0.8%) but no pain or apprehension. All remaining shoulders were stable. Compared with the normal shoulder, there was statistical difference in external rotation in abduction and at the side as well as in internal rotation but not in forward elevation or abduction. However, no patient considered any measurable loss functionally significant. Of 107 patients who participated in sports, 98 returned to the sport; 7 of the remaining 9 discontinued for reasons other than the shoulder. There were 91 patients who agreed to radiography; 48 had normal findings, 34 had mild arthrosis, 9 had moderate arthrosis, and none had severe arthrosis. Mean postoperative outcome scores were as follows: American Shoulder and Elbow Surgeons, 93.53; Rowe, 91.41; and Western Ontario Shoulder Instability Index, 327.7. There were 125 patients who were satisfied and would undergo the procedure again.

CONCLUSION

The open Bankart procedure remains the standard by which other techniques can be measured for treatment of recurrent, traumatic anterior dislocation of the shoulder.

Natural History of Anterior Shoulder Instability

BACKGROUND

The shoulder is the most complex joint in the body. The large freedom of motion in this joint is the main cause of instability. Instability varies in its degree, direction, etiology and volition and there is a large spectrum of conditions.

METHODS

Based on literature research and also in our own experience, we propose to elucidate the reader about the natural history of instability and its importance for the appropriate management of this pathology, by answering the following questions: What happens in the shoulder after the first dislocation? Which structures suffer damage? Who are the patients at higher risk of recurrence? How does the disease evolve without treatment? Will surgical treatment avoid future negative outcomes and prevent degenerative joint disease? Who should we treat and when?

RESULTS

80% of anterior-inferior dislocations occur in young patients. Recurrent instability is common and multiple dislocations are the rule. Instability is influenced by a large number of variables, including age of onset, activity profile, number of episodes,delay between first episode and surgical treatment.

CONCLUSION

Understanding the disease and its natural evolution is determinant to decide the treatment in order to obtain the best outcome. It is crucial to identify the risk factors for recurrence. Delay in surgical treatment, when indicated, leads to worse results. Surgical technique should address the type and severity of both soft tissue and bone lesions, when present.

Anatomy and Biomechanics of the Unstable Shoulder

PURPOSE

To review the anatomy of the shoulder joint and of the physiology of glenohumeral stability is essential to manage correctly shoulder instability.

METHODS

It was reviewed a large number of recently published research studies related to the shoulder instability that received a higher Level of Evidence grade.

RESULTS

It is reviewed the bony anatomy, the anatomy and function of the ligaments that act on this joint, the physiology and physiopathology of glenohumeral instability and the therapeutic implications of the injured structures.

CONCLUSION

This knowledge allows the surgeon to evaluate the possible causes of instability, to assess which are the structures that must be reconstructed and to decide which surgical technique must be performed.

Bankart Repair Using Modern Arthroscopic Technique

As technology continues to improve, surgeons must regularly re-evaluate techniques to improve efficacy and outcomes. The Bankart repair for shoulder instability has evolved from open reconstruction to minimally invasive arthroscopic techniques, which have the benefit of less pain and morbidity. This technical description and video present a modern arthroscopic technique for Bankart repair used at our institution with high success in an athletic population.

The results of Bankart repair without capsular plication in patients with recurrent traumatic anterior shoulder dislocation

PURPOSE

The aim of this study was to evaluate the results of patients with recurrent anterior shoulder dislocation, who had been treated with repair of the Bankart lesion without capsuler plication.

MATERIAL AND METHOD

The study included 22 shoulders of 22 patients (16 males and 6 females) with a mean age of 28 years, who underwent Bankart repair between 2011 and 2014. Patients with bilateral shoulder instability, multiple instability, >25% glenoid bone loss, and those with a history of shoulder surgery were not included in the study. The average follow-up time was 21.2 months. Evaluation was made of the preoperative number of dislocations, postoperative recurrence, functional status, and daily activity performance of the patients. Shoulder range of motion was measured. The results were evaluated using the Rowe shoulder score and the Oxford shoulder instability score.

RESULTS

Recurrence was observed in only one patient who had a shoulder dislocation after trauma, thus giving a recurrence rate of 4.5%. Shoulder range of motion was full in all except that one patient. The mean Rowe shoulder score was 95.5 (excellent) and Oxford shoulder stability score was 44.6 (excellent).

CONCLUSION

No recurrent shoulder dislocation was observed in patients who underwent Bankart repair surgery. Plication was not performed with the Bankart repair. Close to full range of motion was obtained in all patients. In conclusion, Bankart repair alone can be considered to be sufficient for the treatment of traumatic recurrent anterior shoulder instability.

[Anterior shoulder instabilities: about 73 cases]

Entre 2005 et 2014, 73patients (77 épaules) ont bénéficié d’une intervention de Latarjet pour instabilité antérieure de l’épaule. Nous avons, rétrospectivement, évalué les résultats cliniques et radiologiques de cette technique opératoire. L’intervention a été réalisée pour le traitement d’une luxation récidivante dans 69 cas, subluxation récidivante douloureuse dans 5 cas et 3 épaules douloureuses Tous les patients ont eu une évaluation radiographique avant l’intervention et lors du contrôle le plus récent. Selon le score de Rowe, 73 (94.8 %) des 77 épaules ont obtenu un résultat bon ou excellent. Au plus grand recul, 74 épaules étaient indemnes d’arthrose glénohumérale.

Differential expression of extracellular matrix genes in glenohumeral capsule of shoulder instability patients

Anterior shoulder instability is a common orthopedic problem. After a traumatic shoulder dislocation, patients present a plastic deformation of the capsule. The shoulder instability biology remains poorly understood. We evaluated the expression of genes that encode the cartilage oligomeric matrix protein (COMP), fibronectin 1 (FN1), tenascin C (TNC) and tenascin XB (TNXB) in the glenohumeral capsule of anterior shoulder instability patients and controls. Moreover, we investigated the associations between gene expression and clinical parameters. The gene expression was evaluated by quantitative reverse transcription-polymerase chain reaction in the antero-inferior (macroscopically injured region), antero-superior and posterior regions of the capsule of 29 patients with shoulder instability and 8 controls. COMP expression was reduced and FN1 and TNC expression was increased in the antero-inferior capsule region of cases compared to controls (p < 0.05). TNC expression was increased in the posterior capsule portion of shoulder instability patients (p = 0.022). COMP expression was reduced in the antero-inferior region compared to the posterior region of shoulder instability patients (p = 0.007). In the antero-inferior region, FN1 expression was increased in the capsule of patients with more than one year of symptoms (p = 0.003) and with recurrent dislocations (p = 0.004) compared with controls. FN1 and TNXB expression was correlated with the duration of symptoms in the posterior region (p < 0.05). Thus, COMP, FN1, TNC and TNXB expression was altered across the capsule of shoulder instability patients. Dislocation episodes modify FN1, TNC and TNXB expression in the injured tissue. COMP altered expression may be associated with capsule integrity after shoulder dislocation, particularly in the macroscopically injured portion.

History of surgical intervention of anterior shoulder instability

BACKGROUND

Anterior glenohumeral instability most commonly affects younger patients and has shown high recurrence rates with nonoperative management. The treatment of anterior glenohumeral instability has undergone significant evolution over the 20th and 21 centuries.

METHODS

This article presents a retrospective comprehensive review of the history of different operative techniques for shoulder stabilization.

RESULTS

Bankart first described an anatomic suture repair of the inferior glenohumeral ligament and anteroinferior labrum in 1923. Multiple surgeons have since described anatomic and nonanatomic repairs, and many of the early principles of shoulder stabilization have remained even as the techniques have changed. Some methods, such as the Magnusson-Stack procedure, Putti-Platt procedure, arthroscopic stapling, and transosseous suture fixation, have been almost completely abandoned. Other strategies, such as the Bankart repair, capsular shift, and remplissage, have persisted for decades and have been adapted for arthroscopic use.

DISCUSSION

The future of anterior shoulder stabilization will continue to evolve with even newer practices, such as the arthroscopic Latarjet transfer. Further research and clinical experience will dictate which future innovations are ultimately embraced.

A systematic review and meta-analysis of clinical and patient-reported outcomes following two procedures for recurrent traumatic anterior instability of the shoulder: Latarjet procedure vs. Bankart repair

BACKGROUND

The Bankart repair and Latarjet procedure are both viable surgical options for recurrent traumatic anterior instability of the shoulder joint. The anatomic repair is the more popular option, with 90% of surgeons internationally choosing the Bankart repair as the initial treatment. There has been no previous review directly comparing the 2 techniques. Hence, we aimed to systematically review studies to compare the outcomes of Bankart repairs vs. the Latarjet procedure for recurrent instability of the shoulder.

METHODS

Six electronic databases were searched for original, English-language studies comparing the Bankart and Latarjet procedures. Studies were critically appraised using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Data were extracted from the text, tables, and figures of the selected studies.

RESULTS

Eight comparative studies were identified with 795 shoulders; 416 of them underwent open or arthroscopic Bankart repairs, and 379 were repaired by the open Latarjet procedure. Primary and revision procedures were studied. The Latarjet procedure conferred significantly lower risk of recurrence and redislocation. There was no significant difference in the rates of complication requiring reoperation between the two procedures. Rowe scores were higher and loss of external rotation lower in the Latarjet group compared with the Bankart repair group.

CONCLUSIONS

Our studies demonstrate that the Latarjet procedure is a viable and possibly superior alternative to the Bankart repair, offering greater stability with no significant increase in complication rate. However, the studies identified were retrospective and of limited quality, and therefore randomized controlled trials with large populations of patients or prospective assessment of national orthopedic registries should be employed to confirm our findings.

Biomechanical Comparison of the Latarjet Procedure with and without Capsular Repair

Background

The purpose of this study was to determine if capsular repair used in conjunction with the Latarjet procedure results in significant alterations in glenohumeral rotational range of motion and translation.

Methods

Glenohumeral rotational range of motion and translation were measured in eight cadaveric shoulders in 90° of abduction in both the scapular and coronal planes under the following four conditions: intact glenoid, 20% bony Bankart lesion, modified Latarjet without capsular repair, and modified Latarjet with capsular repair.

Results

Creation of a 20% bony Bankart lesion led to significant increases in anterior and inferior glenohumeral translation and rotational range of motion (p < 0.005). The Latarjet procedure restored anterior and inferior stability compared to the bony Bankart condition. It also led to significant increases in glenohumeral internal and external rotational range of motion relative to both the intact and bony Bankart conditions (p < 0.05). The capsular repair from the coracoacromial ligament stump to the native capsule did not significantly affect translations relative to the Latarjet condition; however it did cause a significant decrease in external rotation in both the scapular and coronal planes (p < 0.005).

Conclusions

The Latarjet procedure is effective in restoring anteroinferior glenohumeral stability. The addition of a capsular repair does not result in significant added stability; however, it does appear to have the effect of restricting glenohumeral external rotational range of motion relative to the Latarjet procedure performed without capsular repair.

The biomechanical effect of shoulder remplissage combined with Bankart repair for the treatment of engaging Hill-Sachs lesions

PURPOSE

The purpose of this study was to determine the biomechanical effects of the remplissage repair combined with Bankart repair for engaging Hill-Sachs lesions on range of motion (ROM), translation, and glenohumeral kinematics.

METHODS

Six cadaveric shoulders were tested using a custom shoulder testing system. ROM, kinematics, and anterior-posterior (AP) and superior-inferior glenohumeral translations were quantified at 0° and 60° glenohumeral abduction. Six conditions were tested: intact, Bankart lesion, Bankart with 40 % Hill-Sachs lesion, Bankart repair, Bankart repair with remplissage, and remplissage repair alone.

RESULTS

Humeral external rotation (ER) and total range of motion increased significantly after the creation of the Bankart lesion at both 0° and 60° abduction. The Bankart repair restored ER to intact values at 0° and 60° abduction, and the addition of the remplissage repair did not significantly alter range of motion from the Bankart repair alone. AP translation increased following the creation of the Bankart and Hill-Sachs lesions and was restored with the Bankart repair; the remplissage did not alter translation from the Bankart repair alone. At maximum ER at 60° abduction, the apex of the humeral head shifted posteriorly and inferiorly with remplissage repair.

CONCLUSIONS

The addition of the remplissage procedure combined with Bankart repair for treatment of large Hill-Sachs lesions had no statistically significant effect on ROM or translation, but altered the kinematics of the glenohumeral joint. Thus, by addressing the humeral bone defect following an anterior shoulder dislocation, the remplissage technique with concurrent Bankart repair may be a relatively minimally invasive option for converting engaging Hill-Sachs lesions to non-engaging and promoting shoulder stability, though further biomechanical and clinical studies are warranted.

ANTERIOR GLENOID RIM EROSION MEASURED BY X-RAY EXAM: A SIMPLE WAY TO PERFORM THE BERNAGEAU PROFILE VIEW

Objective: To analyze whether the Bernageau radiographic view is adequate for studying the anterior glenoid rim and to determine the distance between the posterior and anterior glenoid rims. Methods: Fifty patients (31 males) with a mean age of 34 years were evaluated by positioning their arm at 160° forward flexion and body at 70° to the x-ray chassis, while positioning the x-ray tube at 30° craniocaudally, centered on the scapula spine. Three of the authors measured the distance between the posterior and anterior glenoid rim three times. The variability and reproducibility of this distance were studied. Three shoulder surgeons performed a subjective evaluation by answering whether it was possible to evaluate the anterior glenoid rim in the view studied. Results: The mean distance was 24.48 mm ± 0.332 mm (left) and 24.82 mm ± 0.316 mm (right). The Anderson-Darling test showed that the measurements had normal distribution, and Pearson's correlation showed significant reproducibility (P < 0.01). The first observer found that 67% of the x-ray images were suitable for evaluating the anterior glenoid rim. The second found that 81% were suitable and the third, 78%. The kappa coefficient showed that the second and third observers had substantial agreement of opinion. Conclusion: The Bernageau view provided a suitable x-ray image for studying the anterior glenoid rim and for assessing erosion after comparison with the unaffected side.

A Meta-Analysis of Arthroscopic versus Open Repair for Treatment of Bankart Lesions in the Shoulder

Background

The optimal treatment for Bankart lesion remains controversial. Therefore, we performed this meta-analysis to compare the clinical outcomes of patients managed with open Bankart repair versus arthroscopic Bankart repair.

Material/Methods

After systematic review of online databases, a total of 11 trials with 1022 subjects were included. The methodological quality of randomized controlled trials (RCTs) was assessed using the PEDro critical appraisal tool, and non-RCTs were evaluated by Newcastle-Ottawa (NO) quality assessment tool. Outcomes of shoulder stability, range of motion (ROM), functional scales, and surgical times were analyzed.

Results

Data synthesis showed significant differences between the two strategies, with regards to stability of the shoulder (P=0.008, RR=0.94, 95% CI: 0.89 to 0.98), and ROM (P<0.001, SMD=−0.47, 95% CI: −0.72 to −0.22).

Conclusions

Open Bankart repair produced a more stable shoulder but had a relatively poor shoulder motion, compared with arthroscopic Bankart repair, for the treatment of Bankart lesion.

Profile of collagen gene expression in the glenohumeral capsule of patients with traumatic anterior instability of the shoulder

Objective

To evaluate the expression of the genes COL1A1, COL1A2, COL3A1 and COL5A1 in the glenohumeral capsule of patients with traumatic anterior instability of the shoulder.

Methods

Samples from the glenohumeral capsule of 18 patients with traumatic anterior instability of the shoulder were evaluated. Male patients with a positive grip test and a Bankart lesion seen on magnetic resonance imaging were included. All the patients had suffered more than one episode of shoulder dislocation. Samples were collected from the injured glenohumeral capsule (anteroinferior region) and from the macroscopically unaffected region (anterosuperior region) of each patient. The expression of collagen genes was evaluated using the polymerase chain reaction after reverse transcription with quantitative analysis (qRT-PCR).

Results

The expression of COL1A1, COL1A2 and COL3A1 did not differ between the two regions of the shoulder capsule. However, it was observed that the expression of COL5A1 was significantly lower in the anteroinferior region than in the anterosuperior region (median ± interquartile range: 0.057 ± 0.052 vs. 0.155 ± 0.398; p = 0.028) of the glenohumeral capsule.

Conclusion

The affected region of the glenohumeral capsule in patients with shoulder instability presented reduced expression of COL5A1.

Factors affecting capsular volume changes and association with outcomes after Bankart repair and capsular shift

BACKGROUND

Capsular laxity is a main contributing factor in recurrent shoulder instability and is suggested to be correlated with increased capsular volume. Arthroscopic capsular shift combined with Bankart repair can reduce the capsular volume and reinforce the redundant capsule; however, as the capsuloligamentous structure has viscoelastic properties, it is possible for the shifted and tensioned capsule of the glenohumeral joint to slowly stretch out again over time, resulting in an increase in capsular volume.

PURPOSE

To analyze changes in capsular volume of the glenohumeral joint over time after arthroscopic Bankart repair and capsular shift, the factors associated with these changes, and their relevance to outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Included in this study were 105 patients (mean age, 25.8 ± 8.2 years) who underwent arthroscopic Bankart repair and capsular shift for anterior shoulder instability and computed tomography arthrography (CTA) at 3 months and 1 year postoperatively and whose various functional outcomes were evaluated preoperatively and at the last follow-up (>12 months). Among these patients, 27 also had preoperative CTA. These 27 patients were used to make comparisons between preoperative and 3-month postoperative CTA measurements, and all 105 patients were used for all other comparisons. Two raters measured the separate anterior and posterior capsular volume and cross-sectional area at the 5-o'clock position using 3-dimensional (3D) Slicer software. These measurements were subsequently adjusted for each glenoid size. The changes in capsular volume and cross-sectional area at the 5-o'clock position over time, the factors related to higher change in anterior capsular volume, and their correlation with outcomes were evaluated.

RESULTS

Three months postoperatively, the total and anterior capsular volume and anterior cross-sectional area significantly decreased; however, these values increased again at 1 year postoperatively (all P < .01). The inter- and intraobserver reliabilities of the measurements were excellent (interclass correlation coefficient = 0.717-0.945). Female sex, being an elite athlete, and more dislocations before surgery were related to a higher increase in anterior capsular volume at 1 year (all P < .05). Eight patients had redislocation, and 18 exhibited positive apprehension test postoperatively, and these patients showed significantly higher increases in anterior and total capsular volume at 1 year than did those without redislocation or positive apprehension sign (all P < .01). However, with the exception of Rowe score, a higher increase in anterior capsular volume was not related to functional outcome measures.

CONCLUSION

Surgeons should be aware of the re-increase in anterior capsular volume or restretching trait of the anterior capsule over time, even after successful arthroscopic Bankart repair and capsular shift. In this study, women, elite athletes, and those with frequent dislocations were at high risk of capsular restretching. An increase in capsular volume was related to redislocation and positive apprehension sign as well as with Rowe score.

Approach to the treatment of primary anterior shoulder dislocation: A review

Glenohumeral joint dislocation is common among younger, active patients. Anterior dislocation is the most common direction of instability following a traumatic event. Due to a high rate of recurrence following primary traumatic anterior shoulder dislocation, an evidence-based approach is necessary to determine the best treatment regime for a patient presenting with this problem. A history, physical examination, and radiographic imaging can help guide treatment recommendations by determining the extent of soft tissue damage following dislocation. Controversies in the treatment of the first-time dislocator include the length and position of immobilization following dislocation, and the role of initial surgical stabilization. This article outlines the treatment options for the first-time glenohumeral dislocator, with an emphasis on the available evidence in the literature. Where applicable, the criteria known as the Strength of Recommendation Taxonomy were used to summarize the strength of evidence available for recommendations.

Biomechanical analysis of the modified Bristow procedure for anterior shoulder instability: is the bone block necessary?

BACKGROUND

Anterior shoulder instability with bone loss can be treated successfully with the modified Bristow procedure. Opinions vary regarding the role of the soft-tissue sling created by the conjoined tendon after transfer. Therefore, the aim of this study was to determine the effect of the modified Bristow procedure and conjoined tendon transfer on glenohumeral translation and kinematics after creating anterior instability.

METHODS

Eight cadaveric shoulders were tested with a custom shoulder testing system. Range-of-motion, translation, and kinematic testing was performed in 60° of glenohumeral abduction in the scapular and coronal planes under the following conditions: intact joint, Bankart lesion with 20% glenoid bone loss, modified Bristow procedure, and soft tissue-only conjoined tendon transfer.

RESULTS

A Bankart lesion with 20% bone loss resulted in significantly increased external rotation and translation compared with the intact condition (P < .05), as well as an anterior shift of the humeral head apex at all points of external rotation. Both the modified Bristow procedure and soft-tissue Bristow procedure maintained the increase in external rotation but resulted in significantly decreased translation (P < .05). There was no difference in translation between the 2 reconstructions.

CONCLUSIONS

The increase in external rotation suggests that the modified Bristow procedure does not initially restrict joint motion. Translational stability can be restored in a 20% bone loss model without a bone block, suggesting the importance of the soft-tissue sling.

Shoulder instability in the military

Shoulder instability is common in military populations, and this demographic represents individuals at high risk for recurrence. Surgical management is often indicated, especially in high-demand young individuals, and provides a predictable return to military duties. Accurate recognition of glenoid bone loss and other associated anatomic lesions is of importance for appropriate selection between arthroscopic capsulolabral repair and bony reconstruction procedures. A thorough understanding of underlying pathology, diagnostic testing, and available treatment options provides for optimal care of the unstable shoulder.

Gene expression analysis in patients with traumatic anterior shoulder instability suggests deregulation of collagen genes

Shoulder dislocation occurs in 1-2% of the population. Capsular deformation is a key factor in shoulder dislocation; however, little is known about capsule biology. We evaluated, for the first time in literature, the expression of COL1A1, COL1A2, COL3A1 and COL5A1 in the antero-inferior, antero-superior and posterior regions of the glenohumeral capsule of 31 patients with anterior shoulder instability and eight controls. The expression of collagen genes was evaluated by quantitative reverse transcription-PCR. The expression of COL1A1, COL3A1 and the ratio of COL1A1/COL1A2 were increased in all three portions of the capsule in patients compared to controls (p < 0.05). COL1A2 expression was upregulated in the antero-superior and posterior sites of the capsule of patients (p < 0.05). The ratio of COL1A2/COL3A1 expression was reduced in capsule antero-inferior and posterior sites of patients compared to controls (p < 0.05). In the capsule antero-inferior site of patients, the ratios of COL1A1/COL5A1, CO1A2/COL5A1 and COL3A1/COL5A1 expression were increased (p < 0.05). In patients, COL1A1/COL5A1 was also increased in the posterior site (p < 0.05). We found deregulated expression of collagen genes across the capsule of shoulder instability patients. These molecular alterations may lead to modifications of collagen fibril structure and impairment of the healing process, possibly with a role in capsular deformation.

A large humeral avulsion of the glenohumeral ligaments decreases stability that can be restored with repair

BACKGROUND

Humeral avulsion of the glenohumeral ligaments (HAGL) has become a recognized cause of recurrent shoulder instability; however, it is unknown whether small and large HAGL lesions have similarly destabilizing effects and if large lesion repair results in restoration of stability.

QUESTIONS/PURPOSES

In a cadaver model, we evaluated the effect of small and large HAGL lesions and large HAGL lesion repair on glenohumeral ROM, translation, and kinematics.

METHODS

We measured rotational ROM, humeral head translation under load, and humeral head apex position in eight cadaveric shoulders. Each specimen was tested in 60° glenohumeral abduction in the scapular and coronal planes under four conditions: intact, small HAGL lesion (mean ± SD length, 18 ± 1.8 mm), large HAGL lesion (36.8 ± 3.6 mm), and after large HAGL lesion repair. For each condition, we measured maximum internal and external rotation with 1.5 Nm of torque; glenohumeral translation in 90° external rotation with 15- and 20-N force applied in the anterior, posterior, superior, and inferior directions; and humeral head apex position throughout ROM. Repeated-measures ANOVA was used for statistical analysis.

RESULTS

Small HAGL lesions did not change ROM, translation, or kinematics from the normal shoulder; however, these parameters changed with large HAGL lesions. Maximum external rotation and total ROM increased in the scapular (13.8° ± 9.4°, p < 0.001; 19.0° ± 16.5°, p < 0.001) and coronal (21.4° ± 10.6°, p < 0.001; 29.1° ± 22.1°, p < 0.001) planes. With anterior force, anterior-inferior translation increased in both planes (mean increase for both loads and planes: anterior: 9.1 ± 9.5 mm, p < 0.01; inferior, 5.7 ± 6.6 mm, p < 0.03). In the coronal plane, posterior and inferior translation also increased (4.9 ± 5.4 mm, p < 0.01; 7.1 ± 9.9 mm, p < 0.03; averaged for both loads). The humeral head apex shifted 3.7 ± 4.9 mm anterior (p = 0.04) and 2.8 ± 2.6 mm lateral (p = 0.004) in the scapular plane and 3.7 ± 3.4 mm superior (p = 0.006) and 4.1 ± 2.6 mm lateral (p < 0.001) in the coronal plane. HAGL lesion repair decreased ROM and translation in both planes and restored humeral head position in maximum external rotation.

CONCLUSIONS

Anterior large HAGL lesions increase ROM and glenohumeral translation. After large HAGL lesion repair, stability of the shoulder can be restored.

CLINICAL RELEVANCE

Surgeons should be aware of the possibility of HAGL lesions in patients with shoulder instability, and if large HAGL lesions are diagnosed, surgeons should consider repairing the lesions.

Effect of Bankart repair on the loss of range of motion and the instability of the shoulder joint for recurrent anterior shoulder dislocation

BACKGROUND

Bankart repair postoperative complications include loss of shoulder motion and shoulder instability. The primary reason that postoperative complications develop may be excessive imbrication of the anterior band of the inferior glenohumeral ligament (AIGHL) or inadequate repair position. The purpose of this study was to quantitatively evaluate the influence of inadequate repair by computer simulation for a normal shoulder joint.

METHODS

Magnetic resonance images of 10 normal shoulder joints were acquired for 7 positions every 30° from the maximum internal rotation to the maximum external rotation with the arm abducted at 90°. The shortest 3-dimensional path of the AIGHL in each rotational orientation was calculated. We used computer simulations to anticipate the loss of motion and instability by changing the AIGHL length and insertion sites on the glenoid.

RESULTS

The AIGHL length measured 50 ± 5 mm at the maximum external shoulder rotation. AIGHL shortening by 3, 6, and 9 mm made the angle of maximum external rotation 80°, 68°, and 54°, respectively. A superior deviation of 3, 6, and 9 mm on the glenoid insertion resulted in a maximum external rotation angle of 85°, 79°, and 77°. An inferior deviation of 3, 6, and 9 mm produced humeral head translation of 1.7, 2.9, and 3.6 mm.

CONCLUSION

Simulation of both excessive imbrication and deviation of the insertion position led to quantitative prediction of the resulting loss of motion and instability. These findings will be useful for anticipating complications after Bankart repair.

LEVEL OF EVIDENCE

Basic science study, computer modeling, imaging.

Epidemiology of primary anterior shoulder dislocation requiring closed reduction in Ontario, Canada

BACKGROUND

There is a lack of high-quality population-based literature describing the epidemiology of primary anterior shoulder dislocation.

PURPOSE

To (1) calculate the incidence density rate (IDR) of primary anterior shoulder dislocation requiring closed reduction (CR; "index event") in the general population and demographic subgroups, and (2) determine the rate of and risk factors for repeat shoulder CR.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

All patients who underwent shoulder CR by a physician in Ontario between April 2002 and September 2010 were identified with administrative databases. Exclusion criteria included age <16 and >70 years, posterior dislocation, and prior shoulder dislocation or surgery. Index event IDR was calculated for all populations/subgroups, and IDR comparisons were made. Repeat shoulder CR was sought until September 2012. Risk factors for repeat shoulder CR were identified with a Prentice, Williams, and Peterson proportional hazards model.

RESULTS

There were 20,719 persons (median age, 35 years; 74.3% male) who underwent a shoulder CR after a primary anterior shoulder dislocation (23.1/100,000 person-years). The IDR was highest among young males (98.3/100,000 person-years). A total of 3940 (19%) patients underwent repeat shoulder CR after a median of 0.9 years, of which 41.7% were ≤20 years of age. Less than two-thirds of all first repeat shoulder CR events occurred within 2 years; in fact, 95% occurred within 5 years. The risk of repeat shoulder CR was lowest if the primary reduction had been performed by an orthopaedic surgeon (hazard ratio [HR], 0.76; 95% CI: 0.64, 0.90; P = .002) or was associated with a humeral tuberosity fracture (HR, 0.71; CI, 0.53, 0.95; P = .02). Older age (HR, 0.97; CI, 0.97, 0.98; P < .0001) and higher medical comorbidity score (HR, 0.92; CI, 0.87, 0.98; P = .009) were also protective. Risk was highest among males (HR, 1.26; CI, 1.16, 1.36; P < .0001) and patients from low-income neighborhoods (HR, 1.23; CI, 1.13, 1.34; P < .0001).

CONCLUSION

Young male patients have the highest incidence of primary anterior shoulder dislocation requiring CR and the greatest risk of repeat shoulder CR. Patient, provider, and injury factors all influence repeat shoulder CR risk. A comprehensive understanding of the epidemiology of primary anterior shoulder dislocation will aid management decisions and injury prevention initiatives.

Changes to the mechanical properties of the glenohumeral capsule during anterior dislocation

The glenohumeral joint is the most frequently dislocated major joint in the body, and instability due to permanent deformation of the glenohumeral capsule is a common pathology. The corresponding change in mechanical properties may have implications for the ideal location and extent of plication, which is a common clinical procedure used to repair the capsule. Therefore, the objective of this study was to quantify the mechanical properties of four regions of the glenohumeral capsule after anterior dislocation and compare the properties to the normal glenohumeral capsule. Six fresh-frozen cadaveric shoulders were dislocated in the anterior direction with the joint in the apprehension position using a robotic testing system. After dislocation, mechanical testing was performed on the injured glenohumeral capsule by loading the tissue samples in tension and shear. An inverse finite element optimization routine was used to simulate the experiments and obtain material coefficients for each tissue sample. Cauchy stress-stretch curves were then generated to represent the mechanical response of each tissue sample to theoretical loading conditions. Based on several comparisons (average of the material coefficients, average stress-stretch curve for each region, and coefficients representing the average curves) between the normal and injured tissue samples, the mechanical properties of the injured tissue samples from multiple regions were found to be lower than those of the normal tissue in tension but not in shear. This finding indicates that anterior dislocation primarily affects the tensile behavior of the glenohumeral capsule rather than the shear behavior, and this phenomenon could be caused by plastic deformation of the matrix, permanent collagen fiber rotation, and/or collagen fiber failure. These results suggest that plication and suturing may not be sufficient to return stability to the shoulder after dislocation in all individuals. Thus, surgeons may need to perform a procedure that reinforces or stiffens the tissue itself, such as reconstruction or augmentation, to improve repair procedures.