Subacromial Contact Pressure Research Articles

Surgical Management of Massive Irreparable Cuff Tears: Superior Capsular Reconstruction.

Superior capsular reconstruction (SCR) is a surgical procedure that has been developed to provide an alternative for joint preservation in patients with massive irreparable rotator cuff tears. The purpose of this review is to assess the improvements in biomechanical properties and functional outcomes of this novel procedure. Biomechanically, SCR decreases superior translation and subacromial contact pressure. Glenoid fixation is maximized with three anchors, while margin convergence to any remaining rotator cuff improves stability, and findings vary based on graft type. Clinically, SCR has been associated with improvement in functional outcome in the setting of an isolated procedure, or in conjunction with rotator cuff repair. Outcomes appear to be dependent upon indications. However, in select cases, SCR may even be successful in reversing pseudoparalysis. SCR seems to lead to improved biomechanics for the cuff-deficient shoulder resulting in satisfactory functional outcomes. While surgical techniques have evolved, further research is needed to optimize graft healing and longer follow-up studies are needed to continue to refine indications for SCR as a joint preservation effort in the setting of irreparable massive rotator cuff tears without arthritis.

Biomechanics of tensor fascia lata allograft for superior capsular reconstruction

We hypothesized that in a cadaveric massive rotator cuff tear (MCT) model, a fascia lata (FL) allograft superior capsular reconstruction (SCR) would restore subacromial contact pressure and humeral head superior translation without limiting range of motion (ROM). Therefore, the objective of this study was to compare these parameters between an intact rotator cuff, MCT, and allograft FL SCR. Eight fresh cadavers were studied using a custom shoulder testing system. ROM, superior translation, and subacromial contact pressure were measured in each of 3 states: (1) intact rotator cuff, (2) MCT, and (3) MCT with SCR. Total ROM was increased in the MCT state at 60° of abduction (P = .037). FL SCR did not restrict internal or external rotational ROM. Increased superior translation was observed in the MCT state at 0° and 30° of humeral abduction, with no significant difference between the intact cuff and FL SCR states. The MCT state significantly increased mean subacromial contact pressure at 0° of abduction with 30° and 60° of external rotation, and FL SCR restored this to intact levels. Peak subacromial contact pressure was increased for the MCT state at 0° of abduction with 30° and 60° of external rotation, as well as 30° of abduction with 30° of external rotation. This study demonstrates a tensor FL allograft preparation technique for use in SCR. After MCT, FL SCR restores ROM, superior translation, and subacromial contact pressure to the intact state.

Effect of human dermal allograft thickness on glenohumeral stability for superior capsular reconstruction in irreparable supraspinatus tears: A biomechanical analysis of the superior capsular reconstruction - A cadaveric study.

The objective of this study was to compare the biomechanics of using a double layered human dermal allograft to a single layered human dermal allograft in superior capsular reconstruction. Five cadaveric shoulders were tested. The superior translation of the humerus and the subacromial contact pressure were measured at 0°, 30° and 60° of glenohumeral abduction in the following six conditions: (1) intact rotator cuff, (2) irreparable supraspinatus tear, (3) superior capsular reconstruction using a double layered human dermal allograft with and (4) without posterior suturing, (5) superior capsular reconstruction using a single human dermal allograft with and (6) without posterior suturing. There was a significant increase in superior translation of the humerus and subacromial contact pressure when comparing torn supraspinatus to intact shoulder. All superior capsular reconstruction repairs lead to a reduction in superior translation and subacromial contact pressures compared to after the supraspinatus tear except for single layered superior capsular reconstruction repair without posterior suturing. There was no difference in superior translation and subacromial contact pressures comparing the intact shoulder to any of the superior capsular reconstruction constructs. Superior capsular reconstruction using a single or double layered human dermal allograft improves superior translation after supraspinatus repair. There is some biomechanical benefit of a double layered human dermal allograft technique over a single layered graft technique in superior capsular reconstruction. IV.

Effect of biceps rerouting technique to restore glenohumeral joint stability for large irreparable rotator cuff tears: a cadaveric biomechanical study

The concept of stabilizing the humerus has taken on an important role in the treatment of irreparable cuff tears, and the biceps rerouting (BR) method is considered one of the most effective treatments in this field. The study aimed to evaluate the biomechanical effects of BR for large irreparable rotator cuff tears (LICTs). A total of 8 cadaveric shoulders were used for testing under 5 conditions: intact shoulder, LICT, partial repair (PR), BR, and biceps rerouting with side-to-side repair (BRSS). Total rotational range of motion was measured at 40°, then 20°, and finally 0° of glenohumeral (GH) abduction. Superior humeral translation and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation at each abduction angle. Repeated-measures analyses of variance with Tukey post hoc tests were used for statistical comparisons. Superior humeral translation was significantly decreased in the BR and BRSS conditions compared with the LICT and PR conditions at 0° and 20° of GH abduction (P < .001). BR and BRSS significantly reduced subacromial contact pressure compared with LICT and PR at 0° of GH abduction (P < .001). There was no significant decrease in total rotational range of motion after BR at any abduction angle. BR biomechanically restored shoulder stability without overconstraining range of motion in an LICT model.

Arthroscopic Superior Capsular Reconstruction with Dermal Allograft for the Treatment of a Massive Irreparable Rotator Cuff Tear.

A massive, irreparable rotator cuff tear represents a challenging treatment scenario with respect to surgical intervention. Traditionally, surgical options have included reverse total shoulder arthroplasty, hemiarthroplasty, or rotator cuff repair; however, these techniques may not necessarily restore proper anatomy to the superior capsule, a structure implicated in the maintenance of subacromial contact pressures and the prevention of superior glenohumeral translation. Indications for arthroscopic superior capsular reconstruction include massive, irreparable supraspinatus and/or infraspinatus tears and failure of conservative treatment beyond subjective pain thresholds and dysfunction tolerability. Adequate latissimus dorsi, pectoralis major, and deltoid function helps to ensure the appropriate level of shoulder stability and the ability to complete the necessary rehabilitation protocol. The current surgical guide details the clinical evaluation, surgical technique, and rehabilitation protocol for patients undergoing arthroscopic superior capsular reconstruction for a massive, irreparable rotator cuff tear involving the subscapularis, supraspinatus, and infraspinatus. The procedure is performed arthroscopically with the patient in a beach-chair position, starting first with anterior and lateral portal placement for comprehensive diagnostic shoulder arthroscopy assessing rotator cuff damage. Single-row suture repair of the subscapularis and infraspinatus is performed, followed by concomitant subacromial bursectomy, decompression, and coracoplasty to aid in visualization, avoid graft abrasion, and provide access to marrow elements. Suture anchor placement, allograft fixation, and appropriate suture management are highlighted, as well as rehabilitation timelines, complications, and clinical pearls.

Superior Capsule Reconstruction With Subacromial Allograft Spacer: Biomechanical Cadaveric Study of Subacromial Contact Pressure and Superior Humeral Head Translation

To investigate the biomechanical effects of superior capsule reconstruction with subacromial allograft spacer on superior humeral head translation and subacromial contact pressure. Eight cadaveric shoulder specimens were tested in 4 conditions: (1) intact rotator cuff, (2) supraspinatus tear and superior capsule excision, (3) superior capsule reconstruction with human dermal allograft, and (4) superior capsule reconstruction with subacromial resurfacing using human dermal allograft. In each condition, specimens were tested at 0, 30, 60, and 90° of shoulder abduction in balanced and unbalanced loaded states for subacromial contact pressure and superior humeral head translation. Statistical comparisons were made using a repeated-measures analysis of variance test, followed by a Tukey post hoc test for pairwise comparisons. A P value <.05 was set as statistically significant. Superior humeral head translation and subacromial contact pressure were increased after irreparable rotator cuff tear (P= .001). There was no significant difference between superior capsule reconstruction and intact cuff in regard to superior humeral head translation and subacromial contact pressure at all abduction angles. Superior capsule reconstruction with subacromial resurfacing decreased superior humeral head translation relative to intact (0°, P= .004; 30°, P= .02; 60°, P= .08; 90°, P= .01), superior capsule reconstruction (0°, P= .001; 30°, P= .003; 60°, P= .019; 90°, P= .001), and cuff-deficient states (P= .001). Superior capsule reconstruction with subacromial resurfacing resulted in nonsignificant increases in subacromial contact pressure relative to intact cuff at 0 to 90° abduction angles. Superior capsule reconstruction with subacromial resurfacing using human dermal allograft results in decreased superior humeral head translation relative to superior capsule reconstruction with human dermal allograft only, while increasing subacromial contact pressure. Superior capsule reconstruction with subacromial resurfacing using human dermal allograft reduces superior humeral head translation while increasing subacromial contact pressure in a cadaveric model.

Irreparable Rotator Cuff Tears: A Biomechanical Comparison of Superior Capsuloligamentous Complex Reconstruction Techniques and an Interpositional Graft Technique.

Background:Irreparable rotator cuff tears lead to superior translation of the humeral head. Numerous surgical management options are available to treat the condition.Purpose:To compare superior capsule stability among different types of patch grafting in irreparable rotator cuff tears.Methods:Six cadaveric shoulders were tested in a custom-designed shoulder testing system. Superior translation of the humerus and subacromial contact pressure were quantified in an intact condition (condition 1), after cutting the supraspinatus tendon (condition 2), and after additionally cutting the superior capsuloligamentous complex (condition 3). The results were compared among 3 types of patch grafting, in which capsule reconstruction was achieved by glenoidal 3-point (condition 4) or 2-point (condition 5) fixation or by affixing a graft below the acromion (condition 6).Results:No significant difference in subacromial pressure was measured by reconstruction with 2 or 3 anchors compared with conditions 1 and 2 (P > .05). However, with 3-point fixation, lower levels of pressure were measured than with 2-point fixation. Moreover, superior translation values were lower with 3-point fixation; the same applied for values of the preserved capsule as compared with the torn capsule. In condition 6, a significant increase in pressure in the neutral position was documented (P < .05).Conclusion:The superior capsuloligamentous complex plays an important role in stabilizing the glenohumeral joint. The results suggest that with additional medial anchoring at the coracoid base, the depressing and centering effect of the superior complex can probably be regained in a more physiological way compared with a reconstructed capsule with 2 glenoid attachments or with an interpositional graft below the acromion.

Superior Capsular Reconstruction for Massive Rotator Cuff Tears

» A massive rotator cuff tear is defined as a tear involving &gt;2 tendons or &gt;5 cm of retraction.» Superior capsular reconstruction is done with either a folded fascia lata autograft (6 to 8 mm in thickness) or acellular dermal allograft (3 to 4 mm in thickness). The graft is secured arthroscopically with anchors on the superior glenoid rim and multiple anchors on the humeral head with use of a transosseous-equivalent repair technique.» Superior capsular reconstruction is indicated for younger patients with massive and irreparable rotator cuff tears involving the supraspinatus and infraspinatus with minimal arthritis, intact subscapularis, and a functional deltoid. Contraindications include bone defects, stiffness, and moderate to severe arthropathy.» Arthroscopic superior capsular reconstruction with fascia lata autograft or humeral dermal allograft is a surgical option, with multiple studies showing statistically significant improvement in short-term outcomes for both pain and function among younger patients with massive irreparable rotator cuff tears. The long-term clinical effectiveness and value have yet to be determined.» Biomechanical data suggest improved restoration of superior glenohumeral stability with decreased subacromial contact pressures in association with the use of the 8-mm fascia lata graft as compared with the 4-mm acellular humeral dermal allograft. In addition, fascia lata graft has shown less elongation and thinning than humeral dermal graft.» Either fascia lata autograft or humeral dermal allograft may be used clinically for arthroscopic superior capsular reconstruction; however, a graft thickness of at least 3 mm is recommended to decrease the risk of radiographic and clinical failure.» No comprehensive quality-of-life or cost-comparison analyses are available to compare superior capsular reconstruction, reverse total shoulder arthroplasty (rTSA), tendon transfer, and partial rotator cuff repair for the treatment of massive irreparable rotator cuff tears. However, the potential higher cost of superior capsular reconstruction and the lack of long-term clinical outcomes or revision data suggest that either an attempt at repair or primary arthroplasty may be more cost-effective than superior capsular reconstruction.» Long-term outcome data are essential to determine the role of superior capsular reconstruction for young patients with massive irreparable rotator cuff tears.» Superior capsular reconstruction using fascia lata autograft may provide a different biomechanical and biological healing environment compared to acellular dermal allograft. Thus, the clinical outcome data between the 2 graft methods should not be generalized.

Biomechanical analysis of latissimus dorsi tendon transfer with and without superior capsule reconstruction using dermal allograft

Irreparable rotator cuff tears (ICTs) remain a challenging treatment dilemma. Superior capsule reconstruction (SCR) acts as a static stabilizer to decrease superior humeral head migration. Latissimus dorsi tendon transfers (LDTs) dynamically decrease superior humeral head migration and improve external rotation. We hypothesized that the dynamic stabilizing effect of the latissimus transfer plus the static stabilizing effect of SCR would improve shoulder kinematics in shoulders with ICTs. Eight fresh-frozen cadaveric shoulders were tested in 5 conditions: (1) intact, (2) ICT (supraspinatus plus anterior half of infraspinatus), (3) SCR with dermal allograft, (4) SCR plus LDT, and (5) LDT alone. Rotational range of motion, superior translation, anteroposterior translation, and peak subacromial contact pressure were measured at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane. Statistical analysis was performed using a repeated-measures analysis of variance test, followed by a Tukey post hoc test for pair-wise comparisons. ICTs increased total shoulder rotation, superior translation, posterior translation, and peak subacromial contact pressure. SCR plus LDT significantly decreased internal rotation only at 60° of abduction. The effect of SCR plus LDT was most evident at lower levels of abduction. At the mid range of abduction (30°), the static stabilizing effect diminishedbut the dynamic stabilizing effect remained, allowing SCR plus LDT to reduce superior translation more effectively than SCR with dermal allograft alone. Adding SCR to LDT adds static stabilization to a dynamic stabilizer. Therefore, SCR plus LDT may provide additional stability at the low to mid ranges of abduction.

Reconstruction capsulaire supérieure par la longue portion du biceps dans les ruptures irréparables du supraspinatus : une étude biomécanique cadavérique

IntroductionThe superior articular capsule complements the rotator cuff's function in shoulder stability. With irreparable rotator cuff tears, superior capsular reconstruction (SCR) improves dynamic glenohumeral (GH) joint kinematics. We present a novel method of SCR in cadaveric shoulders using the long head of bicep (LHB) tendon instead of previously explored fascia lata autograft, thereby reducing harvest site and suture anchor associated complications. HypothesisThis novel method of SCR using the LHB is feasible biomechanically in restoring shoulder stability in irreparable supraspinatus tendon tear. Materials and MethodsSeven cadaveric shoulders were tested in a custom shoulder testing system. Superior translation of the humerus, subacromial contact pressure and area, and glenohumeral range of motion were tested at 0°, 30°, and 60° of glenohumeral abduction in the following conditions: (1) Intact shoulder, (2) simulated complete supraspinatus tendon tear, (3) modified SCR using LHB, (4) and Modified SCR using LHB and side to side repair augmentation. ResultsThe complete cuff tear shifted the humeral head superiorly as compared to the intact shoulder. Subacromial peak contact pressure was also increased at 30° and 60̊ while contact area was increased at 0̊ and 30̊. The modified SCR both with and without side-to-side repair shifted the humeral head inferiorly at 30̊ and 60̊, with contact area further reduced at 60̊. Both techniques had comparable results for contact pressure and total rotational range of motion. ConclusionThe LHB with appropriate distal insertion on the greater tuberosity restores shoulder stability in irreparable rotator cuff tears by re-centering the humeral head on the glenoid. Level of evidenceBasic Science Study, Biomechanical Testing.

A biomechanical cadaveric study of patellar tendon allograft as an alternative graft material for superior capsule reconstruction

In a cadaveric irreparable rotator cuff tear model, patellar tendon allograft-superior capsule reconstruction (PT-SCR) will restore glenohumeral stability and reduce subacromial contact pressures without significant graft deformation during testing. Eight cadaveric shoulders were tested in a custom shoulder testing system. Rotational range of motion (ROM), superior translation, and subacromial contact pressure were measured in the following experimental conditions: intact rotator cuff, irreparable supraspinatus tear (massive cuff tear [MCT]), and PT-SCR. MCT and PT-SCR resulted in significantly increased total ROM at all degrees of abduction compared with the intact state (P < .001). In both 0° and 30° of glenohumeral abduction, MCT showed a significant increase in superior translation compared with the intact state (P < .001). Application of the PT-SCR resulted in a decrease of superior translation compared with MCT (P < .001). At 0° abduction/60° external rotation and 0° abduction/90° external rotation, MCT showed significantly greater peak subacromial contact pressure compared with the intact state (P < .006). At both of these positions, PT-SCR was able to reduce peak pressure to lower than or no significant difference from the intact state. There was no statistically significant change in graft thickness, length, or width after testing. PT-SCR was able to reduce superior translation of the humeral head and peak subacromial contact pressure without restricting ROM. Furthermore, there was no significant graft deformation during testing. PT-SCR in this validated cadaveric model demonstrates favorable biomechanical properties and is a viable source of graft material for SCR.

Superior capsular reconstruction for irreparable supraspinatus tendon tears using the long head of biceps: A biomechanical study on cadavers

IntroductionThe superior articular capsule complements the rotator cuff's function in shoulder stability. With irreparable rotator cuff tears, superior capsular reconstruction (SCR) improves dynamic glenohumeral (GH) joint kinematics. We present a novel method of SCR in cadaveric shoulders using the long head of bicep (LHB) tendon instead of previously explored fascia lata autograft, thereby reducing harvest site and suture anchor associated complications. HypothesisThis novel method of SCR using the LHB is feasible biomechanically in restoring shoulder stability in irreparable supraspinatus tendon tear. Materials and methodsSeven cadaveric shoulders were tested in a custom shoulder testing system. Superior translation of the humerus, subacromial contact pressure and area, and glenohumeral range of motion were tested at 0°, 30°, and 60° of glenohumeral abduction in the following conditions: (1) intact shoulder, (2) simulated complete supraspinatus tendon tear, (3) modified SCR using LHB, (4) and modified SCR using LHB and side-to-side repair augmentation. ResultsThe complete cuff tear shifted the humeral head superiorly as compared to the intact shoulder. Subacromial peak contact pressure was also increased at 30° and 60° while contact area was increased at 0° and 30°. The modified SCR both with and without side-to-side repair shifted the humeral head inferiorly at 30° and 60°, with contact area further reduced at 60°. Both techniques had comparable results for contact pressure and total rotational range of motion. ConclusionThe LHB with appropriate distal insertion on the greater tuberosity restores shoulder stability in irreparable rotator cuff tears by re-centering the humeral head on the glenoid. Level of evidenceBasic science study, biomechanical testing.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis

To assess an anterior cable reconstruction (ACR) using autologous proximal biceps tendon for large to massive rotator cuff tears. Nine cadaveric shoulders (mean age, 58years) were tested with a custom testing system. Range of motion, superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction. Five conditions were tested: intact, stage II tear (supraspinatus), stage II tear+ ACR, stage III tear (supraspinatus+ anterior half of infraspinatus), and stage III tear+ ACR. ACR involved a biceps tendon tenotomy at the transverse humeral ligament, preserving its labral attachment. ACR included nonpenetrating suture-loop fixation using 2 side-to-side sutures and an anchor at the articular margin to restore anatomy and secure the tendon along the anterior edge of the cuff defect. ACR was performed in 20° glenohumeral abduction and 60° ER. ACR for both stage II and stage III showed significantly higher total range of motion compared with intact at all angles (P ≤ .001). ACR significantly decreased superior translation for stage II tears at 0°, 30°, and 60° ER for both 0° and 20° abduction (P ≤ .01) and for stage III tears at 0° and 30° ER for both 0° and 20° abduction (P ≤ .004). ACR for stage III tear significantly reduced peak subacromial contact pressure at 30° and 60° ER with 0° and 40° abduction and at 30° ER with 20° abduction (P ≤ .041). ACR using autologous biceps tendon biomechanically normalized superior migration and subacromial contact pressure, without limiting range of motion. ACR may improve rotator cuff tendon repair longevity by providing basic static ligamentous support to the dynamic tendon while helping to limit superior migration without restricting glenohumeral kinematics.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Restricting Range of Motion

Objectives:Large rotator cuff defects involving the supraspinatus and infraspinatus tendons, either due to irreparability or after partial repair lack superior capsule support. Any remaining tendon is at risk for tear progression as the tendon must function as both a dynamic tendon and static ligamentous structure. Our purpose was to biomechanically assess an anterior cable reconstruction (ACR) using autologous biceps tendon. We hypothesized that ACR will normalize superior migration and subacromial contact, without limiting range of motion.Methods:Nine cadaveric shoulders were tested using a custom testing system. Glenohumeral kinematics and subacromial contact pressure were measured using a MicroScribe 3DLX and a Tekscan pressure sensor. Each specimen was tested in five conditions: Intact, Stage 2 tear (supraspinatus), Stage 2 tear + ACR, Stage 3 tear (supraspinatus + anterior half of infraspinatus), Stage 3 tear + ACR. ACR involved a biceps tendon tenotomy at the transverse humeral ligament preserving its labral attachment. ACR included “loop-around” suture fixation using two side-to-side sutures and an anchor at the articular margin in order to restore anatomy and secure the tendon along the anterior edge of the cuff defect. ACR was performed in glenohumeral 20° abduction and 60° external rotation. Specimens were tested at 0°, 20°, and 40° of glenohumeral abduction. Total rotational range of motion was measured with 2.2 Nm of torque under a physiologic muscle load. A superiorly unbalanced load was applied to measure superior translation and contact pressure. Repeated measures analysis of variance was used for statistical significance (P < 0.05).Results:The average specimen age was 58 years (range 33-77). Stage 2 and 3 tears showed increased total range of motion at all abduction angles (P < 0.007). ACR after both Stage 2 and 3 tears showed greater total range of motion at 20° abduction (P = 0.035 and P = 0.040) and 40° abduction (P = 0.003 and P < 0.001). The ACR conditions showed significantly higher total ranges of motion compared to Intact (P ≤ 0.007). Superior translation increased significantly from Intact for Stage 2 tears at 7/12 positions (P ≤ 0.014) and Stage 3 tears at all positions except 40° abduction, 90° external rotation (ER) (P < 0.001). At 0° abduction, ACR significantly decreased superior translation for Stage 2 tears at 0°, 30°, and 60° ER (P < 0.01) and Stage 3 tears at 0° and 30° ER (P < 0.001). At 20° abduction, ACR significantly reduced superior translation for Stage 2 tears at 0°, 30°, and 60° ER (P < 0.013) and Stage 3 tears at 0° and 30° ER (P < 0.004). At 40° abduction, ACR significantly decreased superior translation only for Stage 3 tears at 0° ER (P = 0.006). Peak contact pressure significantly increased with Stage 3 tears at 7/12 positions (P ≤ 0.023). ACR significantly reduced peak subacromial contact pressure for Stage 3 tears at: 0° abduction, 30° and 60° ER (P < 0.007); 20° abduction, 30° ER (P < 0.041); 40° abduction, 30° and 60° (peak only) ER (P < 0.024).Conclusion:ACR using autologous biceps tendon can biomechanically normalize superior migration and subacromial contact pressure, without limiting range of motion, similar to superior capsule reconstruction. ACR may improve rotator cuff tendon longevity by providing basic static ligamentous support while helping to maintain normal glenohumeral kinematics.

Cross Body Stretching for Internal Rotation Deficit.

Posterior shoulder tightness and internal rotation deficit at the glenohumeral joint occur often in athletes who participate in throwing sports, racquet and crosse sports, or swimming (1–3). This tightness and decreased internal rotation motion may contribute to shoulder impingement pain through elevation of subacromial contact pressure at the greatest external rotation (4).This deficit can be corrected through passive and active stretching methods performed by a therapist or self-administered by the patient. Among the stretching techniques is the easy-to-perform cross body stretch (CBS). The newest systematically reviewed evidence indicates that the CBS immediately, and over the short-term, effectively reduces the rotation deficit and shoulder tightness compared to other common methods (2,5,6). The Figure demonstrates this stretching technique. The CBS is a fast-acting, low, or no-cost effective option to help treat glenohumeral internal rotation deficit.Figure: CBS: pull arm across the chest while creating tension in the muscles of the shoulder. Hold stretch for 10 to 15 s and repeat three times. Switch arms and repeat.

A biomechanical cadaveric study comparing superior capsule reconstruction using fascia lata allograft with human dermal allograft for irreparable rotator cuff tear

Biomechanical and clinical success of the superior capsule reconstruction (SCR) using fascia lata (FL) grafts has been reported. In the United States, human dermal (HD) allograft has been used successfully for SCRs; however, the biomechanical characteristics have not been reported. Eight cadaveric shoulders were tested in 5 conditions: (1) intact; (2) irreparable supraspinatus tear; (3) SCR using FL allograft with anterior and posterior suturing; (4) SCR using HD allograft with anterior and posterior suturing; and (5) SCR using HD allograft with posterior suturing. Rotational range of motion, superior translation, glenohumeral joint force, and subacromial contact were measured at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane. Graft dimensions before and after testing were also recorded. Biomechanical parameters were compared using a repeated-measures analysis of variance with Tukey post hoc test, and graft dimensions were compared using a Student t-test (P < .05). Irreparable supraspinatus tear significantly increased superior translation, superior glenohumeral joint force, and subacromial contact pressure, which were completely restored with the SCR FL allografts. Both SCR HD allograft repairs partially restored superior translation and completely restored subacromial contact and superior glenohumeral joint force. The HD allografts significantly elongated by 15% during testing, whereas the FL allograft lengths were unchanged. Single-layered HD SCR allografts partially restored superior glenohumeral stability, whereas FL allograft SCR completely restored the superior glenohumeral stability. This may be due to the greater flexibility of the HD allograft, and the SCR procedure used was developed on the basis of FL grafts.

Biomechanical Effects of Acromioplasty on Superior Capsule Reconstruction for Irreparable Supraspinatus Tendon Tears

Background: Acromioplasty is increasingly being performed for both reparable and irreparable rotator cuff tears. However, acromioplasty may destroy the coracoacromial arch, including the coracoacromial ligament, consequently causing a deterioration in superior stability even after superior capsule reconstruction. Purpose/Hypothesis: The purpose of this study was to investigate the effects of acromioplasty on shoulder biomechanics after superior capsule reconstruction for irreparable supraspinatus tendon tears. The hypothesis was that acromioplasty with superior capsule reconstruction would decrease the area of subacromial impingement without increasing superior translation and subacromial contact pressure. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen cadaveric shoulders were evaluated using a custom shoulder testing system. Glenohumeral superior translation, the location of the humeral head relative to the glenoid, and subacromial contact pressure and area were compared among 4 conditions: (1) intact shoulder, (2) irreparable supraspinatus tendon tear, (3) superior capsule reconstruction without acromioplasty, and (4) superior capsule reconstruction with acromioplasty. Superior capsule reconstruction was performed using the fascia lata. Results: Compared with the intact shoulder, the creation of an irreparable supraspinatus tear significantly shifted the humeral head superiorly in the balanced muscle loading condition (without superior force applied) (0° of abduction: 2.8-mm superior shift [P = .0005]; 30° of abduction: 1.9-mm superior shift [P = .003]) and increased both superior translation (0° of abduction: 239% of intact [P = .04]; 30° of abduction: 199% of intact [P = .02]) and subacromial peak contact pressure (0° of abduction: 308% of intact [P = .0002]; 30° of abduction: 252% of intact [P = .001]) by applying superior force. Superior capsule reconstruction without acromioplasty significantly decreased superior translation (0° of abduction: 86% of intact [P = .02]; 30° of abduction: 75% of intact [P = .002]) and subacromial peak contact pressure (0° of abduction: 47% of intact [P = .0002]; 30° of abduction: 83% of intact [P = .0005]; 60° of abduction: 38% of intact [P = .04]) compared with after the creation of a supraspinatus tear. Adding acromioplasty significantly decreased the subacromial contact area compared with superior capsule reconstruction without acromioplasty (0° of abduction: 26% decrease [P = .01]; 30° of abduction: 21% decrease [P = .009]; 60° of abduction: 61% decrease [P = .003]) and did not alter humeral head position, superior translation, or subacromial peak contact pressure. Conclusion: Superior capsule reconstruction repositioned the superiorly migrated humeral head and restored superior stability in the shoulder joint. Adding acromioplasty decreased the subacromial contact area without increasing the subacromial contact pressure. Clinical Relevance: When superior capsule reconstruction is performed for irreparable rotator cuff tears, acromioplasty may help to decrease the postoperative risk of abrasion and tearing of the graft beneath the acromion.

Posterior Capsular Plication Constrains the Glenohumeral Joint by Drawing the Humeral Head Closer to the Glenoid and Resisting Abduction

Background:Shoulder pain is a common problem, with 30% to 50% of the American population affected annually. While the majority of these shoulder problems improve, there is a high rate of recurrence, as 54% of patients experience persistent symptoms 3 years after onset.Purpose:Posterior shoulder tightness has been shown to alter glenohumeral (GH) kinematics. Clinically, posterior shoulder contractures result in a significant loss of internal rotation and abduction (ABD). In this study, the effect of a posterior capsular contracture on GH kinematics was investigated using an intact cadaveric shoulder without violating the joint capsule or the rotator cuff.Study Design:Controlled laboratory study.Methods:Glenohumeral motion, humeral load, and subacromial contact pressure were measured in 6 fresh-frozen left shoulders during passive ABD from 60° to 100° using an automated robotic upper extremity testing system. Baseline values were compared with the experimental condition in which the full thickness of posterior tissues was plicated without decompressing the joint capsule.Results:Posterior soft tissue plication resulted in increased compression between the humeral head and the glenoid (axial load) at 90° of ABD. Throughout ABD, the posterior contracture increased the anterior and superior moment on the humeral head, but it did not change the GH kinematics in this intact model. As a result, there was no increase in the subacromial contact pressure during ABD with posterior plication.Conclusion:In an intact cadaveric shoulder, posterior contracture does not alter GH motion or subacromial contact pressure during passive ABD. By tightening the soft tissue envelope posteriorly, there is an increase in compressive load on the articular cartilage and anterior/superior force on the humeral head. These findings suggest that subacromial impingement in the setting of a posterior soft tissue contracture may result from alterations in scapulothoracic motion, not changes in GH kinematics.Clinical Relevance:This investigation demonstrates that posterior capsular plication increases the axial load on the shoulder joint during ABD. While a significant difference from baseline was observed in the plicated condition, posterior capsular plication did not change GH motion or subacromial contact pressure significantly.

Biomechanical Analysis of Articular-Sided Partial-Thickness Rotator Cuff Tear and Repair

Background: Articular-sided partial-thickness rotator cuff tears are common injuries in throwing athletes. The superior shoulder capsule beneath the supraspinatus and infraspinatus tendons works as a stabilizer of the glenohumeral joint. Purpose: To assess the effect of articular-sided partial-thickness rotator cuff tear and repair on shoulder biomechanics. The hypothesis was that shoulder laxity might be changed because of superior capsular plication in transtendon repair of articular-sided partial-thickness rotator cuff tears. Study Design: Controlled laboratory study. Methods: Nine fresh-frozen cadaveric shoulders were tested by using a custom shoulder-testing system at the simulated late-cocking phase and acceleration phase of throwing motion. Maximum glenohumeral external rotation angle, anterior translation, position of the humeral head apex with respect to the glenoid, internal impingement area, and glenohumeral and subacromial contact pressures were measured. Each specimen underwent 3 stages of testing: stage 1, with the intact shoulder; stage 2, after creation of articular-sided partial-thickness tears of the supraspinatus and infraspinatus tendons; and stage 3, after transtendon repair of the torn tendons by using 2 suture anchors. Results: Articular-sided partial-thickness tears did not significantly change any of the shoulder biomechanical measurements. In the simulated late-cocking phase, transtendon rotator cuff repair resulted in decreased maximum external rotation angle by 4.2° (P = .03), posterior shift of the humeral head (1.1-mm shift; P = .02), decreased glenohumeral contact pressure by 1.7 MPa (56%; P = .004), and decreased internal impingement area by 26.4 mm2 (65%; P < .001) compared with values in the torn shoulder. In the acceleration phase, the humeral head shifted inferiorly (1.2-mm shift; P = .03 vs torn shoulder), and glenohumeral anterior translation (1.5-mm decrease; P = .03 vs torn shoulder) and subacromial contact pressure (32% decrease; P = .004 vs intact shoulder) decreased significantly after transtendon repair. Conclusion: Transtendon repair of articular-sided partial-thickness supraspinatus and infraspinatus tears decreased glenohumeral and subacromial contact pressures at time zero; these changes might lead to reduced secondary subacromial and internal impingements and consequently progression to full-thickness rotator cuff tear. However, repair of the tendons decreased anterior translation and external rotation and changed the positional relationship between the humeral head and the glenoid. Clinical Relevance: Careful attention should be paid to shoulder laxity and range of motion when transtendon repair is chosen to treat articular-sided partial-thickness rotator cuff tears, specifically in throwing athletes.

Role of the superior shoulder capsule in passive stability of the glenohumeral joint

The shoulder capsule is the main static stabilizer of the glenohumeral joint. However, few studies specifically address the function of the superior shoulder capsule, which is usually damaged in patients with complete rotator cuff tears. Therefore, the purpose of this study was to determine the biomechanical contribution of the superior shoulder capsule to passive stability of the glenohumeral joint. Seven cadaveric shoulders were tested with a custom testing system. Glenohumeral translations, subacromial contact pressure, and glenohumeral external and internal rotations were quantified at 5°, 30°, and 60° of glenohumeral abduction. Data were compared among 3 conditions: (1) intact superior capsule, (2) after detaching the superior capsule from the greater tuberosity (tear model), and (3) after complete removal of the superior capsule from the greater tuberosity to the superior glenoid (defect model). A tear of the superior capsule significantly (P < .05) increased anterior and inferior translations compared with those in the intact capsule. Creation of a superior capsular defect significantly (P < .05) increased glenohumeral translation in all directions, subacromial contact pressure at 30° of glenohumeral abduction, and external and internal rotations compared with those of the intact capsule. The superior shoulder capsule plays an important role in passive stability of the glenohumeral joint. A tear in the superior capsule at the greater tuberosity, which may be seen with partial rotator cuff tears, increased anterior and inferior translations. A defect in the superior capsule, seen in massive cuff tears, increased glenohumeral translations in all directions.