Simulated capsulolabral lesion in cadavers: dislocation does not result from a bankart lesion only

A cadaveric study of the posterior band of the inferior glenohumeral ligament of the shoulder and its dynamic behaviour in different arm positions

Purpose

The inferior glenohumeral ligament (IGHL) is composed of three parts: the anterior branch or band (AB), the axillary pouch and the posterior band (PB). The latter has rarely been studied. We aim to describe the PB of the IGHL and its dynamic behaviour in different arm positions.

Methods

Twelve fresh cadaveric shoulders were used and the two bands (AB and PB) of the IGHL were dissected and isolated, taking away all muscle, ligaments and capsule. Characteristics of the bands were studied in five positions: maximum external rotation (ER1), abduction (ABD), internal rotation (IR), ABD external rotation (ER2) and anterior elevation-adduction-IR (Hawkins-Kennedy test position). Progressive and randomized sectioning of the bands and capsule with a scalpel was performed to study its impact on mobility and translation of the glenohumeral joint.

Results

The bands that tensioned first were in ER1, the AB at 97 ± 9° (80-110); in ER2, the AB at 81 ± 19° (30-100); in IR, the PB at 64 ± 9° (50-80); and in ABD, the PB at 87 ± 10° (70-105). Isolated sectioning of the AB had no effect on ABD, whilst isolated sectioning of the PB allowed greater ABD. In ER2, the AB limited anterior translation. After sectioning the AB, anterior translation remained limited by the PB, which wrapped around the humeral head and locked the joint by pressing the two joint surfaces tightly together. In Hawkins-Kennedy position anterior elevation-adduction-IR, the AB is the first constraint and the posterior translation was limited by the PB alone only in four cases.

Conclusions

When the IGHL is isolated, ligament limitation of glenohumeral ABD seems to be uniquely dependent on the PB. In the Hawkins and Kennedy position, the AB is the first constraint. In the case of an isolated lesion to the AB, the PB participates in anterior stabilization of the shoulder by wrapping around the humeral head that cannot dislocate. These findings confirm the role of the PB in glenohumeral joint stability.

Level of Evidence

Level IV.

The biomechanical effect of injury and repair of the inferior glenohumeral ligament on glenohumeral stability: Contribution of the posterior band

BACKGROUND

Many surgical procedures are proposed to manage shoulder instability with recurrent dislocation but there is still a high rate of failure or complications. Repairs are often limited to anterior part of inferior glenohumeral ligament but some authors are reporting better clinical results if its posterior band is also repaired. This biomechanical study aimed to investigate the impact of a supplementary posterior injury compared with an isolated anterior injury and to analyze the contribution of a posterior repair of the inferior glenohumeral ligament compared with an isolated anterior repair.

METHODS

Six fresh-frozen cadaveric shoulders were tested intact and after both anterior and posterior injuries and repairs of the inferior glenohumeral ligament. Shoulders were placed at 90° of humerothoracic elevation in scapular plane and 60° of external rotation. Joint stability was analyzed by successively applying anterior, posterior, inferior and superior glenohumeral displacements and measuring the resulting forces or by applying an anteroinferior loading and measuring three-dimensional head displacements. Maximal range of external rotation was also measured.

FINDINGS

Combined anterior and posterior injuries of the inferior glenohumeral ligament were necessary to obtain significant instabilities in anterior and inferior directions. A complementary repair of the posterior band improved the biomechanical stability of the glenohumeral joint compared to an isolated anterior repair when anterior and posterior bands are injured. No reduction of external rotation was observed after repairs compared to intact condition.

INTERPRETATION

These results show the biomechanical interest of this surgical procedure and contribute to document its relevance in clinical practice.

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.

Hybrid suture technique vs simple suture technique for antero-inferior labral tears: Two years' clinical outcomes

Background

We previously reported a hybrid suture technique, wherein mattress and simple suturing are used to create Mason-Allen configuration, with low recurrence rates. This comparative study looking at the two years’ clinical outcomes of arthroscopic anterior labral repair using the hybrid suture technique versus simple suture technique.

Methods

We identified 103 patients who underwent arthroscopic anterior labral repair from 2010 to 2015 with 2-year follow-up. The patients were categorized into two groups: hybrid suture technique (65 patients) and simple suture technique (38 patients). Clinical outcomes measures included UCLA shoulder score, Constant Shoulder Score, Numerical Pain Rating Scale, and Oxford Instability score.

Results

Mean age of the patients was 27.02 ± 9.76 years (17–63), with 91 males and 12 females. At 24 months, both groups showed significant improvement in post-operative clinical scores compared to pre-operation. The patients in hybrid sutures technique demonstrated significant improvement in Constant Shoulder Score, UCLA shoulder score and Oxford Instability score compared to simple suture group at 3 months follow up. (121.98 ± 21.05 vs 109.32 ± 21.15, p < 0.05; 65.5 ± 19 vs 57.4 ± 17.6, p < 0.05; 27.3 ± 5.7 vs 23.7 ± 5.0, p < 0.05; 29.3 ± 8.9 vs 33.4 ± 8.2, p < 0.05). The postoperative recurrence rate was comparable between both groups (hybrid suture group 7.81% vs simple suture group 7.84%).

Conclusions

Arthroscopic anterior labral repair with hybrid suture technique offers significant early improvements in clinical scores and low recurrence rate compared to simple suture technique at 2-year follow-up.

Level of evidence

Level III; Retrospective Cohort Design; Treatment study.

Controversies In The Surgical Management Of Shoulder Instability: Associated Soft Tissue Procedures

Background:

The glenohumeral joint is a ball-and-socket joint that is inherently unstable and thus, susceptible to dislocation. The traditional and most common anatomic finding is the Bankart lesion (anterior-inferior capsule labral complex avulsion), but there is a wide variety of anatomic alterations that can cause shoulder instability or may be present as a concomitant injury or in combination, including bone loss (glenoid or humeral head), complex capsule-labral tears, rotator cuff tears, Kim´s lesions (injuries to the posterior-inferior labrum) and rotator interval pathology.

Methods:

A review of articles related to shoulder anatomy and soft tissue procedures that are performed during shoulder instability arthroscopic management was conducted by querying the Pubmed database and conclusions and controversies regarding this injury were exposed.

Results:

Due to the complex anatomy of the shoulder and the large range of movement of this joint, a wide variety of anatomic injuries and conditions can lead to shoulder instability, specially present in young population. Recognizing and treating all of them including Bankart repair, capsule-labral plicatures, SLAP repair, circumferential approach to pan-labral lesions, rotator interval closure, rotator cuff injuries and HAGL lesion repair is crucial to achieve the goal of a stable, full range of movement and not painful joint.

Conclusion:

Physicians must be familiarized with all the lesions involved in shoulder instability, and should be able to recognize and subsequently treat them to achieve the goal of a stable non-painful shoulder. Unrecognized or not treated lesions may result in recurrence of instability episodes and pain while overuse of some of the techniques previously described can lead to stiffness, thus the importance of an accurate diagnosis and treatment when facing a shoulder instability.

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.

Hyper extension-internal rotation (HERI): A new test for anterior gleno-humeral instability

BACKGROUND

Anterior shoulder dislocation causes injury to the inferior gleno-humeral ligament (IGHL) and capsule. Clinical manoeuvres currently used to evaluate the IGHL test for, and may induce, apprehension. We developed the hyper extension-internal rotation (HERI) test to assess the IGHL and inferior capsule without causing apprehension or inducing a risk of gleno-humeral dislocation.

HYPOTHESIS

The HERI test is easy to perform and reproducible, induces no risk of gleno-humeral dislocation during the manoeuvre, and causes no apprehension in the patients.

MATERIAL AND METHODS

We studied 14 fresh cadaver shoulders. Each specimen was positioned supine with the lateral edge of the scapula on the table and the upper limb hanging down beside the table under the effect of gravity. This position produced hyperextension and internal rotation of the gleno-humeral joint. For each shoulder, the range of extension (°) was measured before and after isolated IGHL section. Then, we performed the HEIR test in 50 patients with chronic unilateral anterior gleno-humeral instability and we compared the range of extension between the normal and abnormal sides.

RESULTS

In the cadaver study, isolated IGHL section increased the angle of extension by a mean of 14.5° (11°-18°) compared to the pre-injury values. In the clinical study, the mean difference in extension angles between the normal and abnormal sides was 14.5°. The patients reported no apprehension during the HERI test.

CONCLUSION

The angle of extension increases after section or injury of the IGHL in cadaver specimens and patients, respectively. When the inferior capsule and IGHL are damaged, the angle of extension increases compared to the normal side. Lesions to these structures can be evaluated clinically by performing the HERI test.

LEVEL OF EVIDENCE

III.

Anterior shoulder dislocation increases the propensity for recurrence: a cadaveric study of the number of dislocations and type of capsulolabral lesion

BACKGROUND

The number of anterior shoulder dislocations that predispose to recurrence is unknown; some clinicians recommend surgical repair after the initial episode and others after multiple recurrences. The purpose of this study was to quantify the forces during successive anterior dislocations of cadaveric shoulders and to inspect the capsule and labrum afterwards, in order to assess the propensity for recurrence.

MATERIALS AND METHODS

Twenty-two human cadaveric shoulders were tested using a custom cadaveric shoulder dislocation device with simulated muscle loading. Each was positioned in the apprehension position and the humerus was moved in horizontal abduction until the shoulder dislocated. The joint reaction force was measured, as was the force that developed passively in the pectoralis major muscle. Following 3 successive dislocations, each was inspected for anterior capsulolabral lesions.

RESULTS

There was a significant decrease in force after the second dislocation. In 11, there was no labral avulsion and a significant decrease in force after the first dislocation. In the other 11, there was a labral avulsion and a significant decrease in force after the second dislocation.

CONCLUSION

Two successive anterior shoulder dislocations may increase propensity for recurrence; but this is influenced by the type of capsulolabral lesion that occurs. No labral avulsion, likely a result of capsular stretching, may be a worse prognostic finding than labral avulsion after the initial episode.

Capsule function following anterior dislocation: implications for diagnosis of shoulder instability

During shoulder dislocation, the glenohumeral capsule undergoes non-recoverable strain, leading to joint instability. Clinicians use physical exams to diagnose injury and direct repair procedures; however, they are subjective and do not provide quantitative information. Our objectives were to: (1) determine the relationship between capsule function following anterior dislocation and non-recoverable strain; and (2) identify joint positions at which physical exams can be used to detect non-recoverable strain in specific capsule regions. Physical exams were simulated at three joint positions including external rotation (ER) using robotic technology before and after anterior dislocation. The resulting joint kinematics, strain distribution in the capsule, and non-recoverable strain were determined. Following dislocation, anterior translation increased by as much as 48% (0° ER: p = 0.03; 30° ER: p = 0.03; 60° ER: p < 0.01). Capsule sub-regions with less non-recoverable strain required more ER to detect differences in the strain ratios between the intact and injured joint. Strain ratio changes on the humeral side of the posterior axillary pouch (0.31 ± 0.32) were significant at all joint positions (0° ER: p = 0.03; 30° ER: p = 0.048; 60° ER: p = 0.04), whereas strain ratio differences on the humeral side of the anterior axillary pouch (0.18 ± 0.21) were significant only at 60° of ER (p = 0.03). Therefore, standardizing physical exams for joint position could help surgeons identify specific locations of non-recoverable strain that may have been ignored.

Effects of combined anterior and posterior plication of the glenohumeral ligament complex for the repair of anterior glenohumeral instability: a biomechanical study

BACKGROUND

Arthroscopic repair techniques for anterior instability most commonly address only the anterior band of the inferior glenohumeral ligament. This study quantitatively evaluated and compared the combined anterior and posterior arthroscopic plication by repairing both the anterior and posterior bands of the inferior glenohumeral ligament with the anterior arthroscopic plication alone.

MATERIALS AND METHODS

Six cadaveric shoulders were tested in 60° of glenohumeral abduction with 22 N of compressive force in the coronal plane for intact, after anterior capsular stretching, after anterior repair, and after posterior arthroscopic repair. Range of motion, glenohumeral translation, and glenohumeral kinematics throughout the rotational range of motion were measured with a MicroScribe 3DLX (Immersion, San Jose, CA, USA). Glenohumeral contact pressure and area were measured with a pressure measurement system (Tekscan Inc, South Boston, MA, USA).

RESULTS

Stretching the anterior capsule significantly increased external rotation and anterior translation (P < .05). After anterior plication, external rotation was restored to the intact condition, and anterior translation was significantly decreased compared with stretched condition (P < .05). The combined anterior and posterior plication significantly decreased internal rotation compared with the intact condition. The anterior plication shifted the humeral head posterior in external rotation, whereas the combined anterior and posterior plication shifted the humeral head anterior in internal rotation (P < .05). Both repairs led to a decrease in glenohumeral contact area at 45° external rotation (P < .07).

CONCLUSIONS

The addition of a posterior plication to anterior plication for anterior instability has no biomechanical advantage over a typical arthroscopic anterior repair for anterior glenohumeral instability.

Biomechanical effects of arthroscopic capsulorrhaphy in line with the fibers of the anterior band of the inferior glenohumeral ligament

BACKGROUND

There is no consensus as to the amount and direction of capsular plication necessary to correct anterior shoulder instability without overconstraining the joint.

HYPOTHESIS

An arthroscopic capsulorrhaphy in line with the fibers of the inferior glenohumeral ligament (IGHL) in an anterior laxity model will restore glenohumeral kinematics to normal.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six cadaveric specimens were tested in both the scapular and coronal plane in 3 conditions: intact, anterior instability, and plicated. The anterior instability model was created by stretching the shoulder 20% beyond the physiological external rotational range of motion, and plication was achieved by performing a 10-mm arthroscopic plication in line with the fibers of the anterior band of the IGHL.

RESULTS

Stretching significantly increased the rotational range of motion, while plication restored it back to that of the intact condition (P < .05). There were few significant changes in humeral head apex position across all 3 testing conditions. Plication significantly reduced anterior translation compared with the stretched condition (P < .05). Stretching and plication both significantly reduced contact area relative to the intact condition (P < .05). There were no significant differences between any of the 3 conditions for contact pressure and only few significant differences between the conditions for contact peak pressure.

CONCLUSION

A 10-mm capsular plication in line with the fibers of the anterior band of the IGHL effectively reduces capsular laxity without overconstraining the joint.

CLINICAL RELEVANCE

The fibers of the anterior band of the IGHL provide a useful arthroscopic anatomic landmark for the direction of anterior capsulorrhaphy.

Shoulder injuries in the throwing athlete

Shoulder injuries in the throwing athlete are becoming more frequent. Sports specialization at a younger age, playing multiple seasons, increased awareness of injury and injury prevention, advances in diagnosis, and surgical treatment all play a part in the increase in diagnosis of these injuries. Understanding the biomechanics of throwing and pathologies that are encountered in the throwing athlete can aid the clinician in successful diagnosis and nonoperative/operative treatment of the throwing athlete. This article discusses the relevant anatomy, biomechanics, and pathoanatomy of the throwing shoulder. Additionally, understanding the kinetic chain can assist in the nonoperative rehabilitation of the injured shoulder. Surgical reconstruction is indicated when nonoperative efforts have been exhausted and is directed based on the extent of the pathology to the capsuloligamentous structures, labrum, and rotator cuff.

The biomechanical effect of specific labral and capsular lesions on posterior shoulder instability

PURPOSE

In contrast to anterior shoulder instability there seems to be no single key lesion in posterior shoulder instability. Therefore, the purpose of this study was to determine the biomechanical effect of specific posterior capsulolabral lesions. Our hypothesis was that a posterior capsule lesion will have a predominant effect compared to a labrum detachment (Bankart lesion).

METHODS

Stability testing of 16 cadaveric human shoulders was performed. The specimens were distributed to two groups: the labrum lesion group and the capsular lesion group. In the labrum lesion group three different conditions were tested consecutively: posteroinferior Bankart lesion, additive pHAGL lesion, additive posterosuperior Bankart lesion. In the capsular lesion group two conditions were tested: posteroinferior capsule cut including a glenoidal transection of the pIGHL, additive rotator interval and superior capsule lesion (SGHL and CHL cut). All lesions were set arthroscopically. Biomechanical testing was performed in two positions: the sulcus-test position and the jerk-test position each with a passive humerus load of 50 N in the posterior, posteroinferior and inferior direction.

RESULTS

A posteroinferior Bankart lesion resulted in a percentage increase of 86% posterior translation in the jerk position and an increase of 31% inferior translation in the sulcus position. An additional pHAGL lesion resulted in a significant increase of posterior and inferior translation given by 31 and 41% in the jerk position. Regarding the capsular lesions, a cut of the posteroinferior capsule and the pIGHL resulted in a significant increased inferior translation of 53% in the sulcus position but did not cause a significant increase of posterior translation in the jerk position. If an additional rotator interval lesion is set the inferior translation is again significantly increased.

CONCLUSIONS

On the basis of our results traumatic posterior shoulder instability must be suspected to be bidirectional posteroinferior independently if a posterior capsule lesion or a posterior Bankart lesion is evident.

CLINICAL RELEVANCE

Capsular and labral lesions both have a significant biomechanical effect but differ in the predominant direction of instability, which is posterior for the Bankart lesion and inferior for the capsular lesion. An additional pHAGL or rotator interval lesion aggravates the posteroinferior instability and must be respected in the surgical treatment strategy.

Anterosuperior labral tear without biceps anchor involvement: a subtle isolated cause of a painful shoulder

PURPOSE

The purposes of this study were to determine common clinical symptoms related to an anterosuperior labral tear without biceps anchor involvement and to establish the outcome of arthroscopic management of this injury.

METHODS

In our database of arthroscopic procedures we identified 23 patients with an isolated anterosuperior labral tear. The mean age at the time of surgery was 38.3 ± 6.8 years (range, 18 to 59 years). The preoperative clinical diagnosis varied, but an anterosuperior labral isolated lesion was not detected before surgery. The diagnosis of anterosuperior labral tear was made arthroscopically, and the lesion was fixed with a suture anchor technique, by use of 1 single bioabsorbable anchor. Patients were reviewed after a minimum of 2.5 years of follow-up. Clinical outcome was evaluated with the Rowe score, American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, and visual analog scale score.

RESULTS

History, clinical examination, and preoperative imaging usually failed to indicate the presence of an isolated anterosuperior labral tear as the cause of shoulder pain in our patients. Repair of the labral lesions yielded good to excellent results with normalization of the range of motion and a significant improvement in shoulder scores (Rowe, American Shoulder and Elbow Surgeons, Simple Shoulder Test, and visual analog scale).

CONCLUSIONS

Isolated tears of the anterosuperior labrum represent a subtle cause of shoulder pain and dysfunction. The lesion is very difficult to diagnose clinically. Arthroscopic repair is a reliable procedure providing a good outcome in terms of pain relief, patient satisfaction, and shoulder scores.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Loss of external rotation after open Bankart repair: an important prognostic factor for patient satisfaction

The repair of the capsuloligamentous complex during shoulder stabilisation procedures can be followed by a persistent restricted capacity of external rotation. The prognostic importance of this loss in external rotation for patient satisfaction has not previously been evaluated. We therefore followed 68 consecutive patients operated for recurrent traumatic unidirectional anterior instability of the glenohumeral joint to assess the association between loss of external rotation and patient satisfaction. All patients underwent open Bankart repair. Two independent observers carried out a follow-up (5 years on average) after surgery. At follow-up, recurrent dislocation had developed in four of the 68 patients (6%). The median pre-operative Rowe score was 65 (range 42-87), which can be compared with 92 (range 46-100) at the follow-up. Three patients rated their outcome as poor, 13 as fair, 23 as good and 29 as excellent. There was a five-fold increased risk for a poor or fair outcome among patients with loss of external rotation in 0 degrees of abduction (age- and gender-adjusted odds ratio [OR] 5.3; 95% confidence interval [CI] 1.3-22.0, P = 0.0007). A linear association between the degree of loss in external rotation and patient dissatisfaction was found. The risk of being dissatisfied, independent of recurrent dislocation, occasional pain, positive apprehension test, age and gender, more than doubled (OR 2.6; 95% CI 1.4-4.8, P = 0.002) for every 10 degrees of post-operative loss of external rotation. Loss of external rotation almost explained all of the variation in patient satisfaction with a population attributable risk of 0.85 (95% CI 0.20-0.94). We conclude that open Bankart repair with a modified Rowe procedure is an excellent surgical option regarding stability, but restriction in external rotation reduces the likelihood of a satisfied patient.

Biomechanical stability of an arthroscopic anterior capsular shift and suture anchor repair in anterior shoulder instability: a human cadaveric shoulder model

It was hypothesized that an arthroscopic Bankart repair with suture anchors supplies sufficient anterior shoulder stability, which cannot be improved by an additional capsular shift. In an experimental biomechanical human cadaver study, we tested ten fresh human cadaver shoulders in a robot-assisted shoulder simulator. External rotation and glenohumeral translation were measured at 0 degrees and 80 degrees of glenohumeral abduction. All measurements were performed under the following conditions: on the non-operated shoulder; following the setting of three arthroscopic portals; following an arthroscopic anterior capsular shift; following a simulated Bankart lesion; and following an arthroscopic Bankart repair. The application of three arthroscopic portals resulted in a significant increase of the anterior (P = 0.01) and antero-inferior translation (P = 0.03) at 0 degrees and 80 degrees abduction, as well as an increase in external rotation at 80 degrees abduction (P = 0.03). Capsular shift reduced external rotation (P = 0.03), but did not significantly decrease translation. Simulating anterior shoulder instability, glenohumeral translation significantly increased, ranging from 50 to 279% of physiological translation. Arthroscopic shoulder stabilization resulted in a decrease of translation in all tested directions to approximately physiologic levels. External rotation in 0 degrees abduction was thus decreased significantly (P = 0.003) to an average of 19 degrees . The study proved that an arthroscopic anterior capsular shift in a cadaveric model decreases external rotation without a significant influence on glenohumeral translation. Arthroscopic shoulder stabilization with suture anchors thus sufficiently restores increased glenohumeral translation, but also decreases external rotation in neutral abduction. An anatomic reconstruction of the Bankart lesion without overconstraining of the antero-inferior capsule should therefore be the aim in arthroscopic anterior shoulder stabilization.

Effects of posterior-inferior capsular plications in range of motion in arthroscopic anterior Bankart repair: a prospective randomized clinical study

The effects of posterior plications associated with anterior shoulder instability surgery are still unclear both on shoulder range of motion (ROM) and on recurrence rate. The objective of this randomized study is to evaluate the influence of posterior-inferior plications, performed in association with repair of anterior Bankart lesion, on gleno-humeral (GH) range of motion. In a 24-month period, 40 patients were prospectively enrolled in this study. The criteria for inclusion were age between 17 and 40 years, traumatic unidirectional instability, no previous shoulder surgery, no more than three episodes of dislocation, no relevant glenoid bone deficiency, no clinical evidence of pathological anterior inferior laxity (measured with external rotation with the arm at the side inferior to 90 degrees and Gagey sign negative) and arthroscopic finding of isolated anterior Bankart lesion. A total of 20 patients (group A) were randomized to treat Bankart lesion using three bioadsorbable anchors loaded with a #2 braided polyester suture. In 20 randomized patients (group B) two posterior-inferior capsular plications performed with a #1 polidioxanone suture without any capsular shift were added to the same anterior capsulorraphy performed in group A. Postoperative rehabilitation protocol was the same for all 40 patients. Patients were examined preoperatively and at a 2-year follow-up by a single independent expert physician unaware of the surgical procedure. GH ROM, Constant, UCLA and ASES rating scores as well as recurrence of instability were recorded. At follow-up, forward flexion (FF) decreased by a mean value of 14.5 degrees (median -10 degrees ; range -5 degrees to -35 degrees ; P < 0.001) in group B and increased by a mean value of 3.5 degrees (median 0 degrees ; range -25 degrees to 40 degrees ; P < 0.312) in group A; external rotation with arm adducted (ER1) increased by a mean value of 1.8 degrees (median 0 degrees ; range -15 degrees to 30 degrees ; P < 0.924) in group B, and increased by a mean value of 2.6 degrees (median 2.5 degrees ; range -38 degrees to 40 degrees ; P < 0.610) in group A; external rotation with arm abducted at 90 degrees (ER2) decreased by a mean value of 2.9 degrees (median 0 degrees ; range: -20 degrees to 10 degrees ; P < 0.161) in group B and increased by a mean value of 0.7 degrees (median 0 degrees ; range -30 degrees to 25 degrees ; P < 0.837) in group A; the IR2 decreased by a mean value of 2.4 degrees (median -3.5 degrees ; range -15 degrees to 10 degrees ; P < 0.167) in group B and increased by a mean value of 2.2 degrees (median 0 degrees ; range -20 degrees to 30 degrees ; P < 0.456) in group A. The UCLA mean score gains by 43.1% (median 40; P < 0.001) relatively, and of 45.2% relatively (median 40; P < 0.001), respectively, in group B and A, ASES mean score relatively gains by 21.7% (median 21.2%; P < 0.001) in group B, and of 19.2% (median 18.9%; P < 0.001) in group A, and Constant mean score improves by 20.2% (median 16.5; P < 0.001) in group B, and 10.2% (median 8.4%; P < 0.001) in group A. Thus, the only statistical significant differences were the reduction of forward flexion in group B and the improvements of the scores in both groups. No recurrence of instability was found in the plicated group, while in the non-plicated group we had one traumatic recurrence. In conclusion, arthroscopic posterior-inferior plications associated with a Bankart lesion repair in a selected group of patients seem to reduce only FF, without any effect on rotation. A longer follow-up and a larger number of patients are needed to give definitive conclusions on the benefit to the recurrence rate.

Consequences of a Perthes-Bankart lesion in twenty cadaver shoulders

This study investigated whether an anteroinferior capsulolabral lesion is sufficient to allow the humeral head to dislocate and whether a limited inferior approach for creating the lesions influenced the results compared with an all-arthroscopic approach. Four ligamentous zones of the glenohumeral capsule were sequentially detached from the glenoid neck and labrum in 20 cadaver shoulders through an inferior approach. Before and after each resection step, inferior stability was tested using a sulcus test and anterior stability using a drawer test and an apprehension maneuver. Dislocation was only possible when at least 3 zones were cut. This study confirmed that superior and posterior extension of the classic anteroinferior Perthes-Bankart lesion is necessary before the capsular restraint in external rotation and abduction is overcome and dislocation occurs. Lesions other than the Perthes-Bankart need to be investigated when recurrent dislocation is treated, because this anteroinferior injury is most probably not the sole factor responsible for the instability.

A comparison of the spectrum of intra-articular lesions in acute and chronic anterior shoulder instability

PURPOSE

The purpose of the study was to compare the incidence of secondary intra-articular shoulder lesions in patients with acute and chronic anterior shoulder instability. The occurrence of glenoid shape alterations (inverted pear glenoid) in recurrent instability was especially examined.

METHODS

Data for all arthroscopically ascertained intra-articular shoulder lesions in a series of 127 patients with acute and chronic traumatic anterior instability were recorded.

RESULTS

Hemarthrosis was evident in all patients with acute dislocation and in 7 patients with chronic laxity who underwent surgery shortly after a dislocation episode. In both groups the presence of a chondral or osteochondral Hill-Sachs lesion was noted in 112 patients (88.1%), a Bankart lesion was noted in 106 patients (83.46%), an anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion was noted in 13 patients (10.23%), a SLAP lesion was noted in 26 patients (20.47%), a humeral avulsion of the glenohumeral ligament (HAGL) lesion was noted in 2 acutely dislocated shoulders (1.57%), and capsular laxity was noted in 33 patients (25.98%). All ALPSA lesions were noted in patients with chronic instability (P = .044), and both HAGL lesions were found in patients with acute dislocations (P = .002). In patients with acute dislocations the incidence of Bankart lesions was 78.2% (18/23), whereas in chronic cases the incidence of Bankart or ALPSA lesions was 97.11% (101/104) (P = .002). In the group with acute dislocations there was a Hill-Sachs lesion in 15 cases (65.21%) and chronic recurrent instability accounted for 97 cases (93.26%) (P = .001). The capsule was considered lax in 2 patients with acute instability and 31 patients with chronic instability (8.69% v 29.8%, P = .037). The overall frequency of SLAP lesions was not statistically significant between acute and chronic cases (P = .868), unlike their distribution. In acute cases there were 3 type I and 2 type II SLAP lesions, whereas in chronic cases there were 4 type I, 13 type II, 3 type III, and 1 type IV SLAP lesions. Loose bodies were found and removed in 17 chronic and 4 acute cases (16.34% v 13.04%, P = .903). A partial-thickness articular rotator cuff tear was found in 14 patients: 12 with chronic dislocations and 2 with acute dislocations (11.53% v 8.69%, P = .694). The cuff tears were partial articular surface tears, involving less than 25% of the cuff thickness, and were treated with debridement, and cuff repair was not necessary in any case. The inverted pear configuration of the glenoid was found in 16 cases with chronic instability (15.38%), whereas no patient with an acutely dislocated shoulder had an inverted pear-shaped glenoid (P = .044).

CONCLUSIONS

Associated, secondary intra-articular lesions are more frequent in patients with chronic compared with acute shoulder instability, probably as a result of the repeated dislocation or subluxation episodes.

LEVEL OF EVIDENCE

Level IV, prognostic case series.

The role of the subscapularis in preventing anterior glenohumeral subluxation in the abducted, externally rotated position of the arm

BACKGROUND

Current literature suggests that the subscapularis muscle is the main active stabilizer when the humerus is abducted and externally rotated. Conservative treatment of anterior shoulder instability therefore aims at strengthening this muscle. Empirical models, however, have questioned the role of the subscapularis muscle as it has been observed to potentially support dislocation of the subluxated humeral head.

METHODS

Ten human shoulders were loaded with an anterior dislocating force and the effect of different subscapularis tensions on humeral translation was measured with the Motion Analysis system, for the abducted and externally rotated arm and neutral positions. Also, lines of action of the subscapularis segments were measured on a 3D epoxy model.

FINDINGS

Shoulders in which the humeral head migrated antero-superiorly under an external antero-inferior load were observed to dislocate under simulated active subscapularis tension in both positions. In contrast, shoulders in which the head migrated antero-inferiorly remained stable. Twice as many specimens dislocated in the abducted - externally rotated position than in the neutral position. The change in line of action of the subscapularis may account for this change.

INTERPRETATION

Exercises alone are unlikely to be adequate for all patients with anterior instability symptoms. Passive motion pattern of the humeral head might serve as an indicator as to whether the effect of strengthening the subscapularis might stabilize a shoulder without further operation. Development of a clinical test based on these findings might differentiate the non-operative from operative candidates among patients presenting with anterior instability of the shoulder.

Concomitant rotator cuff and capsuloligamentous lesions of the shoulder: a cadaver study

PURPOSE

Rotator cuff lesions have not yet been evaluated in association with capsuloligamentous lesions in an otherwise intact shoulder model. Our hypothesis was that less extensive capsuloligamentous lesions are necessary to allow dislocation in the presence of rotator cuff lesions.

METHODS

The supraspinatus and infraspinatus, or the subscapularis, or all 3 tendons were carefully detached from their insertion without damage to the underlying capsule. Adjacent combinations of 4 zones of the capsuloligamentous complex were then sequentially detached from the glenoid or from the humerus in 80 cadaver shoulders. Stability was tested before and after each resection step; this included testing of inferior stability with a sulcus test, and of anterior stability with a drawer test and with an apprehension maneuver. Findings from these specimens were statistically compared with those from the same types of tests in specimens with intact rotator cuffs.

RESULTS

Subluxation during the drawer and sulcus tests is already reached after the tendon lesion has been created, or after only 1 ligamentous zone has been cut. In the presence of a tendon lesion, at least 1 less cutting step is necessary for dislocation to occur in the apprehension position. There is a difference, however, between glenoid- and humerus-based lesions.

CONCLUSIONS

The humeral head dislocates easily with less extensive capsuloligamentous lesions when rotator cuff lesions are present. In the present experimental model, passive stabilization provided by the rotator cuff appears more easily disrupted when associated with ligamentous lesions on the humeral side than with lesions on the glenoid side. This may be so because interdigitation of the cuff tendons with each other and with the capsule through the rotator cable is maintained with glenoid-sided lesions.

CLINICAL RELEVANCE

Rotator cuff lesions destabilize the glenohumeral joint. This effect is less pronounced when cuff tendons continue to interact with underlying capsuloligamentous structures. This finding may be relevant for small cuff tears and for partial cuff tears, especially those seen after dislocation.