Biomechanical effects of anterior capsular plication and rotator interval closure in simulated anterior shoulder instability

Quantification of the passive behavior of the glenohumeral joint: A biomechanical study

Shoulder stabilization and arthroplasty procedures aim to restore the complex motion innate to the glenohumeral joint relying on proper tensioning of the surrounding soft-tissues at the time of surgery. Joint instability remains a leading cause for revisions of these procedures necessitating a deeper understanding of the passive constraint of the intact glenohumeral joint. The current literature lacks comprehensive analysis of the passive glenohumeral joint in all degrees-of-freedom (DOF). The objective of the present study is to better understand this complex joint by quantifying the passive laxity of the glenohumeral joint in multiple DOFs over a range of motion. Sixteen fresh-frozen cadaveric shoulders were tested in the intact state using a robotic simulator capable of six-DOF motion. The limits of range of motion was quantified in separate laxity tests applying a ± 2 Nm internal-external (IE) torque, ±20 N anterior-posterior (AP) force, ±20 N superior-inferior (SI) force and a 44 N distraction force at six levels of glenohumeral abduction. Overall, glenohumeral joint laxity was greatest between 15° and 45° of abduction except for SI translation which increased with abduction. IE rotation and AP translation were dominated by external rotation and anterior translation, respectively. Although early abduction and late abduction produced similar laxities, the increase in laxity in the mid abduction range indicates it is important to assess the shoulder joint throughout the range of motion and not just at these two end points. The presented laxity data establishes a baseline for intact shoulder laxity over a range of motion in multiple DOFs under known loading conditions.

Anterior Bankart Repair With Superior Capsular Plication Causes Increased Mean Tension in Posterior Glenohumeral Capsule

Purpose

The purpose of this study is to investigate if a biomechanical difference exists in the prerepair and postrepair states of the posterior inferior glenohumeral ligament (PIGHL) following anterior Bankart repair with respect to capsular tension, labral height, and capsular shift.

Methods

In this study, 12 cadaveric shoulders were dissected to the glenohumeral capsule and disarticulated. The specimens were loaded to 5-mm displacement using a custom shoulder simulator, and measurements were taken for posterior capsular tension, labral height, and capsular shift. We measured the capsular tension, labral height, and capsular shift of the PIGHL in its native state and following repair of a simulated anterior Bankart lesion.

Results

We found that there was a significant increase in the mean capsular tension of the posterior inferior glenohumeral ligament (Δ = 2.12 ± 2.10 N; P = .005), as well as posterior capsular shift (Δ = .362 ± 0.365 mm; P = .018). There was no significant change in posterior labral height (Δ = 0.297 ± 0.667 mm; P = .193). These results demonstrate the sling effect of the inferior glenohumeral ligament.

Conclusion

Although the posterior inferior glenohumeral ligament is not directly manipulated during an anterior Bankart repair, when the anterior inferior glenohumeral ligament is plicated superiorly, some of the tension is transmitted to the posterior glenohumeral ligament as a result of the sling effect.

Clinical Relevance

Anterior Bankart repair with superior capsular plication results in an increased mean tension of the PIGHL. Clinically, this may contribute to shoulder stability.

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 Anatomic Glenoid Repair Using Distal Tibial Allograft and an Inferior-to-Superior Capsular Shift

Traumatic anterior dislocation of the shoulder accounts for the vast majority of shoulder dislocations. Recurrence following initial traumatic dislocation is common, and the risk is increased by the presence of both bony and soft-tissue damage. Arthroscopic procedures have been described to address each of these etiologies individually but have not provided a technique to address bony and soft tissue pathology concurrently. This paper describes an all-arthroscopic, anatomic glenoid repair using distal tibial allograft with an inferior-to-superior capsular shift, addressing significant glenoid bone loss and capsular laxity with a single operation.

A comparative study on use of two versus three double-loaded suture anchors in arthroscopic Bankart repair

Objectives

This study aims to compare clinical results of repair using two versus three double-loaded suture anchors in arthroscopic Bankart repair.

Patients and methods

Between July 2012 and December 2017, a total of 40 patients (38 males, 2 females; mean age: 31.6±8.1; range: 17 to 47 years) who underwent Bankart arthroscopic surgery and were followed for minimum two years were retrospectively analyzed. Group 1 (n=17) underwent arthroscopic Bankart repair with two double-loaded suture anchors, while Group 2 (n=23) underwent repair with three double-loaded suture anchors. Clinical outcomes of the patients and recurrences were compared.

Results

At the final postoperative follow-up, a significant improvement was observed in the functional outcomes in all patients. No statistically significant difference was found (p>0.05) in the mean clinical scores of the Constant Shoulder Score between Group 1 (94.2±7.8) and Group 2 (95.4±4.1). There was no significant difference in the mean Rowe scores (Group 1: 95.6±4.6 vs. Group 2: 96.3±3.8, respectively) and external rotation loss (at neutral Group 1: 1.9o vs. Group 2: 2.2o, respectively). Three of our patients had recurrent dislocation during a major traumatic event (n=2 in Group 1 and n=1 in Group 2).

Conclusion

Our study results suggest that stability is not correlated with the use of either two versus three double-loaded suture anchors in arthroscopic Bankart repairs.

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.

Rotator Interval Plication: The "Seamster" Technique

The indications and best technique for plication of the rotator interval capsule, performed as a supplemental procedure at the time of arthroscopic shoulder stabilization, remain a controversial topic. There are currently no well-accepted surgical indication guidelines that have been established. Several biomechanical studies, however, have demonstrated the important contribution of the rotator interval capsule to stability of the glenohumeral joint, and the utilization of rotator interval plication in patients with glenohumeral instability has been supported in several publications. The indications for and surgical steps to accomplish the arthroscopic "seamster" technique for rotator interval plication, used by the authors for >20 years, is described.

Can capsular plication compensate the lack of one suture anchor in an arthroscopic three suture anchor Bankart repair? A comparative study

Objective

The aim of this study was to compare the complication rates and clinical results of labral repair with two suture anchors and capsular plication, and labral repair with three suture anchor fixation in artroscopic Bankart surgery.

Methods

Sixty-nine patients (60 males, 9 females; mean age: 28.2 ± 7.8 years (range: 16–50)) who had undergone arthroscopic repair of a labral Bankart lesion were evaluated. Group A underwent an arthroscopic Bankart repair with three knotless suture anchors, while group B underwent a modified arthroscopic Bankart repair with two knotless suture anchors and an additional capsular plication procedure. The mean follow-up was 52.5 months. Constant Shoulder Score (CSS), Rowe Score (RS), modified UCLA Shoulder Score (mUSS) and range of motion (ROM) were used as outcome measures.

Results

In both groups, a significant improvement was detected in functional outcomes at postoperative last follow-up compared to the preoperative period. No statistically significant difference was found (p > 0.05) in clinical scores (CSS; Group A: 89.7, Group B: 80.2) (RS; Group A: 88.2, Group B: 80.2) (mUSS; Group A: 26.3, Group B: 25.7) external rotation loss (At neutral; Group A: 4.5°, Group B: 5.2°. At abduction; Group A: 4.3°, Group B: 5.7°) and recurrence rates (Group A: 13.3%, Group B: 20.8%). Although the difference was not statistically significant, the recurrence rate was higher in group B (20.8%), compared to group A (13.3%), despite the shorter average follow-up time of group B (p = 0.417).

Conclusions

Arthroscopic repair of labral Bankart lesions with both techniques showed good functional outcomes and stability at the latest follow-up. Higher recurrence rate despite the shorter average follow-up of group B suggests that two anchor usage might not be sufficient for Bankart repair in terms of better stability and less recurrence risk.

Level of evidence

Level III, Therapeutic Study.

Rotator interval closure: inconsistent techniques and its association with anterior instability. A literature review

The Rotator interval (RI) is an anatomic space in the anterosuperior part of the glenohumeral joint. An incompetent or lax RI has been implicated in various conditions of shoulder instability and therefore RI has been frequently touted as an area that is important in preserving stability of the shoulder. Biomechanical studies have shown that repair of RI ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Although varieties of methods have been described for its closure, the optimal surgical technique is unclear with various inconsistencies in incorporation of the closure tissue. This in particular makes the analysis of the RI closure very difficult. The purposes of this study are to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of plication of RI structures in particular to anterior glenohumeral instability, to delineate the differences between an arthroscopic and open RI closure. Additionally, we have proposed a new classification system describing various techniques used during RI closure.

What Are the Effects of Capsular Plication on Translational Laxity of the Glenohumeral Joint: A Study in Cadaveric Shoulders

BACKGROUND

Surgical treatment for shoulder instability generally involves labral repair with a capsular plication or imbrication. Good results are reported in both open and arthroscopic procedures, but there is no consensus on the amount or location of capsular plication that is needed to achieve stability and anatomic anterior, posterior, and inferior translation of the joint.

QUESTIONS/PURPOSES

(1) What are the separate and combined effects of increasing plication magnitude and sequential additive plications in the anterior, posterior, and inferior locations of the joint capsule on glenohumeral joint translation in the anterior, posterior, and inferior directions? (2) What plication location and magnitude restores anterior, posterior, and inferior translation to a baseline level?

METHODS

Fourteen cadaveric shoulders were dissected down to the glenohumeral capsule and underwent instrumented biomechanical testing. Each shoulder was loaded with 22 N in anterior, posterior, and inferior directions at 60° abduction and neutral rotation and flexion and the resulting translation were recorded. Testing was done over baseline (native), stretched (mechanically stretched capsule to imitate a lax capsule), and 5-mm, 10-mm, and 15-mm plication conditions. Individually, for each of the 5-, 10-, and 15-mm increments, plications were done in a fixed sequential order starting with anterior plication at the 3 o'clock position (Sequence I), then adding posterior plication at the 9 o'clock position (Sequence II), and then adding inferior plication at the 6 o'clock position (Sequence III). Each individual sequence was tested by placing 44 N (10 pounds) of manual force on the humerus directed in an anterior, posterior, and inferior direction to simulate clinical load and shift testing. The effect of plication magnitude and sequence on translation was tested with generalized estimating equation models. Translational differences between conditions were tested with paired t-tests.

RESULTS

Translational laxity was highest with creation of the lax condition, as expected. Increasing plication magnitude had a significant effect on all three directions of translation. Plication location sequence had a significant effect on anterior and posterior translation. An interaction effect between plication magnitude and sequence was significant in anterior and posterior translation. Laxity in all directions was most restricted with 15-mm plication in anterior, posterior, and inferior locations. For anterior translational laxity, at 10-mm and 15-mm plication, there was a progressive decrease in translation magnitude (10-mm plication anterior only: 0.46 mm, plus posterior: 0.29 mm, plus inferior, -0.12 mm; and for 15-mm anterior only: -0.53 mm, plus posterior: -1.00 mm, plus inferior: -1.66 mm). For posterior translational laxity, 10-mm and 15-mm plication also showed progressive decrease in magnitude (10-mm plication anterior only: 0.46 mm, plus posterior: -0.25 mm, plus inferior: -1.94; and for 15-mm anterior only: 0.14 mm, plus posterior: -1.54 mm, plus inferior: -3.66). For inferior translational laxity, tightening was observed only with magnitude of plication (anterior only at 5 mm: 0.31 mm, at 10 mm: -1.39, at 15 mm: -3.61) but not with additional plication points (adding posterior and inferior sequences). To restore laxity closest to baseline, 10-mm AP/inferior plication best restored anterior translation, 15-mm anterior plication best restored posterior translation, and 5 mm posterior with or without inferior plication best restored inferior translation.

CONCLUSIONS

Our results suggest that (1) a 10-mm plication in the anterior and posterior or anterior, posterior, and inferior positions may restore anterior translation closest to baseline; (2) 10-mm anterior and posterior or 15-mm anterior plications may restore posterior translation closest to baseline; and (3) 5-mm anterior and posterior or anterior, posterior, and inferior plications may restore inferior translation closest to baseline. Future studies using arthroscopic techniques for plication or open techniques via a true surgical approach might further characterize the effect of plication on glenohumeral translation.

CLINICAL RELEVANCE

This study found that specific combinations of plication magnitude and location can be used to restore glenohumeral translation from a lax capsular state to a native state. This information can be used to guide surgical technique based on an individual patient's degree and direction of capsular laxity. In vivo testing of glenohumeral translation before and after capsular plication will be needed to validate these cadaveric results.

Mapping glenohumeral laxity: effect of capsule tension and abduction in cadaveric shoulders

BACKGROUND

Shoulder capsular plication aims to restore the passive stabilization of the glenohumeral capsule; however, high reported recurrence rates warrant concern. Improving our understanding of the clinical laxity assessment across 2 dimensions, capsular integrity and shoulder position, can help toward the standardization of clinical tools. Our objectives were to test and describe glenohumeral laxity across 5 capsular tension levels and 4 humeral position levels and describe tension-position interplay.

METHODS

We tested 14 dissected cadavers for glenohumeral laxity in 5 directions: anterior, posterior, and inferior translation, and internal and external axial rotation. Laxity was recorded across capsule tension (baseline, stretched, 5 mm, 10 mm, and 15 mm of plication) and position (0°, 20°, 40°, 60° of scapular abduction). Repeated-measures analysis of variance with post hoc contrasts tested the effect of tension, position, and composite tension × position on laxity.

RESULTS

Capsule tension, position, and composite interplay had a statistically significant, although unequal, effect on laxity in each direction. Laxity was consistently overconstrained in 15-mm plication and was overall greatest in 20° and lowest in 60°. Restoration occurred most in 10 mm, but this depended on the position. The composite effect was significant for external and internal rotation and inferior laxity, but laxity at the middle range (20° or 40°) was different than at the end range (0° or 60°) for all directions.

CONCLUSIONS

On average, laxity was restored to baseline tension after 10-mm plication, but this determination varied depending on shoulder position. Middle-range laxity behaved differently than end-range laxity across plication tensions. This information is useful in understanding the unstable shoulder as well as for standardizing clinical laxity assessment.

Recurrent Instability After Arthroscopic Bankart Reconstruction: A Systematic Review of Surgical Technical Factors

PURPOSE

Recurrent instability remains of concern after arthroscopic Bankart reconstruction. We evaluated various technical factors including anchor design, anchor material, number of anchors used, and interval closure on risk of recurrent instability after arthroscopic Bankart reconstruction.

METHODS

A systematic review of MEDLINE and Cochrane databases was conducted, following PRISMA guidelines. Extracted data were recorded on a standardized form. Methodological index for non-randomized studies (MINORS) and Newcastle-Ottawa Scale (NOS) were used to assess study quality and risk bias. Because of study heterogeneity and low levels of evidence, meta-analysis was not possible. Pooled weighted means were calculated and individual study evaluation and comparisons (qualitative analysis) were performed for systematic review.

RESULTS

Of 2097 studies identified, 26 met criteria for systematic review. Pooled weighted means revealed 11.4% versus 15% recurrent instability with 3 or more suture anchors versus fewer than 3 anchors, 10.1% versus 7.8% with absorbable versus nonabsorbable suture anchors, respectively, and 8.0% versus 9.4% with knotless versus standard anchors, respectively. Interval closure did not qualitatively decrease recurrent instability or decrease range of motion.

CONCLUSIONS

Our systematic review reveals that despite individual study, and previous systematic reviews pointing to the contrary, the composite contemporary published literature would support no difference in the risk of recurrent instability after arthroscopic Bankart reconstruction with rotator interval closure, differing numbers of anchors used for the repair, use of knotless versus standard anchors, or use of bioabsorbable versus nonabsorbable anchors. We recommend surgeons focus on factors that have been shown to modify the risk factors after arthroscopic Bankart reconstruction, such as patient selection.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Arthroscopic R-LCL plication for symptomatic minor instability of the lateral elbow (SMILE)

PURPOSE

Minor instability has been proposed as a possible aetiology of lateral elbow pain. This study presents the results of the arthroscopic plication of the radial component of the lateral collateral ligament (R-LCL) to reduce minor instability of the lateral elbow.

METHODS

Twenty-seven patients with recalcitrant lateral epicondylitis who had failed conservative therapy and who had no previous trauma or overt instability, were included. R-LCL plication was performed in the presence of at least one sign of lateral ligamentous patholaxity and one intra-articular abnormal finding. Single-assessment numeric evaluation (SANE), Oxford Elbow Score (OES), quickDASH (Disabilities of the Arm, Shoulder, Hand), patient satisfaction and post-operative range of motion were evaluated.

RESULTS

SANE improved from a median of 30 [2-40] points pre-operatively to 90 [80-100] at final follow-up (p < 0.0001), and 96.3% patients obtained good or excellent subjective results. Post-operative median quickDASH was 9.1 [0-25] points and OES 42 [34-48]. Median post-operative flexion was 145°, and extension was 0°. Post-operative flexion was restrained in seven patients and extension in eight patients; 59% of patients reached full ROM at final follow-up.

CONCLUSIONS

R-LCL plication produces subjective satisfaction and positive clinical results in patients presenting with a symptomatic minor instability of the lateral elbow (SMILE) at 2-year median follow-up. A slight limitation in range of motion is a possible undesired consequence of this intervention.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

The Influence of Surgical Stabilization on Glenohumeral Abduction Using 3-Dimensional Computed Tomography in Patients With Shoulder Instability

PURPOSE

This study compared the amount of glenohumeral abduction during arm abduction in the affected and unaffected shoulders of 3 groups of patients with shoulder instability: failed surgical stabilization, successful surgical stabilization, and unstable shoulder with no prior surgical intervention.

METHODS

All patients underwent bilateral shoulder computed tomography scans in 3 positions: 0° of abduction and 0° of external rotation (0-0 position), 30° of abduction and 30° of external rotation (30-30 position), and arms maximally abducted (overhead position). Three-dimensional computed tomography reconstruction was performed for both shoulders in all 3 positions. A specialized coordinate system marked specific points and directions on the humerus and glenoid of each model. These coordinates were used to calculate the glenohumeral abduction for the normal and affected sides in the 0-0, 30-30, and overhead positions.

RESULTS

Thirty-nine patients with shoulder instability were included, of whom 14 had failed surgical repairs, 10 had successful surgical repairs, and 15 had unstable shoulders with no prior surgical intervention. In the overhead position, patients with failed surgical intervention had significantly less glenohumeral abduction in the failed shoulder (95.6° ± 12.7°) compared with the normal shoulder (101.5° ± 12.4°, P = .02). Patients with successfully stabilized shoulders had significantly less glenohumeral abduction in the successfully stabilized shoulder (93.6° ± 10.8°) compared with the normal shoulder (102.1° ± 12.5°, P = .03). Unstable shoulders with no prior surgical intervention (102.1° ± 10.3°) did not differ when compared with the normal shoulders (101.9° ± 10.9°, P = .95).

CONCLUSIONS

Surgical intervention, regardless of its success, limits the amount of abduction at the glenohumeral joint.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The Rotator Interval of the Shoulder: Implications in the Treatment of Shoulder Instability

Biomechanical studies have shown that repair or plication of rotator interval (RI) ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical outcomes studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Recent studies describing arthroscopic techniques to address these structures have intensified the debate over the potential benefit of these procedures as well as highlighted the differences between open and arthroscopic RI procedures. The purposes of this study were to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of repair or plication of rotator interval structures, and to describe the various surgical techniques used for these procedures and outcomes.