Visualization of the anatomy of the rotator interval and bicipital sheath

A systematic evaluation of the glenohumeral joint should be routinely performed with all shoulder arthroscopy and include all anatomic areas. However, to date, less attention has been given to the insertion of the subscapularis tendon, superior glenohumeral ligament (SGHL), and medial head of the coracohumeral ligament (MCHL). This article outlines arthroscopic techniques that may aid in the evaluation of the anatomy of the rotator interval and bicipital sheath. In this apical region, the CHL contributes fibers to the SGHL (forming the internal reflection of the bicipital groove–SGHL/CHL complex), the subscapularis tendon, and the joint capsule. The CHL is more anterior to the SGHL. There is a distinct anatomic difference between the SGHL/CHL insertion complex and the subscapularis insertion. The normal insertion of the subscapularis tendon is into a small trough on the lesser tuberosity. Together, these structures make up the medial wall of the superior biceps pulley. With the arthroscope advanced to the anterior portion of the joint, the shoulder is elevated from 60° to 90° and a neuroprobe is advanced through the anterior cannula. By internally rotating the arm, the subscapularis tendon insertion and SGHL/CHL complex slacken. A neuroprobe can be placed under the insertion of the subscapularis tendon and SGHL/CHL complex. A 70° arthroscope can aid in visualization with less shoulder elevation. These techniques allow for a thorough visualization of the structures of the rotator interval and medial bicipital sheath.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 1 (January), 2001: pp 107–111     

Postimpingement instability following reverse shoulder arthroplasty: a parametric finite element analysis

BackgroundInstability following reverse shoulder arthroplasty is influenced by various factors such as component design, component positioning, and soft tissue tensioning. Patients may achieve glenohumeral motion beyond initial scapular impingement during activities of daily living which could further compound instability. However, instability/subluxation risk postscapular impingement is not well documented. Conventional range of motion analysis tools cannot account for the restraining effect of soft tissues or subluxation risk after impingement. Using a previously validated finite element analysis approach, the purpose of this study was to investigate the effects of glenoid component lateralization and humeral component angle of inclination (AOI), with or without simulated subscapularis repair, on postimpingement subluxation. We hypothesized that lack of subscapularis repair, a valgus humeral component AOI, and glenoid medialization would all result in greater postimpingement instability.MethodsA FE model of the shoulder including the subscapularis tendon and middle deltoid was created, incorporating a general representation of a commercial reverse shoulder arthroplasty implant placed under the direction of a fellowship-trained shoulder surgeon. The deltoid and subscapularis were tensioned and wrapped around the reconstructed glenohumeral joint prior to simulating motion. Humeral rotations were then prescribed to simulate external rotation (neutral to 50°), extension (neutral to 50°), adduction (neutral to 30°), and abduction (neutral to 90°). The effects of three glenosphere lateralization offsets (2, 4, and 10 mm) and 2 humeral liner angles of inclination (varus-150° and valgus-155°) on subluxation propensities were investigated with and without the subscapularis tendon present.ResultsSimulated subscapularis repair resulted in 21%-34% less postimpingement subluxation. Presence of the subscapularis provided stability over a greater range of abduction. Impingement-free range of motion was similar regardless of the presence or absence of the subscapularis. The valgus AOI resulted in 23% less subluxation during abduction. During other motions however, the valgus AOI resulted in 67%-110% greater postimpingement subluxation (subscapularis present), which further worsened without the subscapularis.ConclusionImplant design modifications to improve stability may not be beneficial for all motions, highlighting the importance of directionality when investigating instability. Liner-bone impingement appears to compound instability/subluxation and the subscapularis appears to restrain postimpingement instability.Level of evidenceBasic Science Study; Computer Modeling     

Releases of subscapularis contracture: an anatomic and clinical study

Correction of anterior subscapularis contracture is an important step in soft-tissue balancing at the time of total shoulder replacement (TSR). An anatomic and clinical investigation was undertaken to investigate the effect of steps involved in subscapularis release. In 14 cadaveric shoulders studied, the subscapularis insertion consisted of three regions: a thick superior tubular tendon (STT), a flat middle tendon, and an inferior portion where the muscle fibers insert directly into the humerus. In 16 consecutive patients undergoing primary TSR for osteoarthritis, measurements of subscapularis length were taken after different releases. An average of 0.9 cm (confidence interval, 0.7-1.1 cm) of excursion was added after anterior capsular release, and an additional 0.7 cm (confidence interval, 0.5-0.9 cm) of excursion was obtained after STT release. Incision of the STT is an alternative means of gaining subscapularis length when balancing the soft tissues in patients with osteoarthritis undergoing TSR.     

Rupture of the subscapularis tendon after shoulder arthroplasty: diagnosis, treatment, and outcome

The purpose of this study was to document the diagnosis, surgical treatment, and functional outcome in patients with subscapularis ruptures after shoulder arthroplasty. Prospective objective and subjective data were collected on 7 patients with symptomatic rupture of the subscapularis tendon after shoulder arthroplasty. Presenting signs and symptoms included pain, weakness in internal rotation, increased external rotation, and anterior instability. All patients were treated with surgical repair of the ruptured tendon. Four required repair augmentation with a transfer of the pectoralis major tendon. After subscapularis repair and pectoralis transfer, 2 patients continued to have anterior instability and required an additional operation to address the instability. At a mean follow-up of 2.3 years (range, 18-55 months), the mean American Shoulder and Elbow Surgeons shoulder score in this study group was 63.2. The mean patient satisfaction rating, on a 10-point scale, was 6.2. Factors associated with post-arthroplasty subscapularis ruptures included subscapularis lengthening techniques used to address internal rotation contracture and previous surgery that violated the subscapularis tendon. Symptomatic subscapularis rupture after shoulder arthroplasty introduces the need for additional surgery and a period of protected or delayed rehabilitation after arthroplasty. Although symptoms were adequately addressed with appropriate surgical treatment, decreased functional outcomes were observed.     

The influence of arthroscopic subscapularis tendon and anterior capsular release on glenohumeral translation: a biomechanical model

The effect of an arthroscopic release of the intraarticular portion of the subscapularis tendon and the anterior capsule on glenohumeral translation was investigated in a cadaveric model. Ten human cadaveric shoulders with a mean age of 63.5 years (range, 52-79 years) were tested in a robot-assisted shoulder simulator. Joint translation was measured before and after an arthroscopic release of the intraarticular portion of the subscapularis tendon and a subsequent release of the anterior capsule at 0 degrees , 30 degrees , 60 degrees , and 90 degrees of glenohumeral elevation. Translation was measured in the anterior, anterior-inferior, and inferior directions under 20 N of applied load. Testing of the specimen revealed that the release of the intraarticular portion of the subscapularis tendon and the anterior capsule increased translation in all directions. Significant increases in translation were observed after release of the intraarticular portion of the subscapularis tendon in the midrange of motion. The influence of the arthroscopic capsular release, in conjunction with the release of the subscapularis tendon, was very high above 60 degrees of elevation. The study indicates that the intraarticular component of the subscapularis tendon functions as a restraint to anterior-inferior translation primarily in the midrange of glenohumeral motion, whereas the anterior capsule adds anterior-inferior stability to the glenohumeral joint mainly above 60 degrees of elevation.     

The comma sign: An arthroscopic guide to the torn subscapularis tendon

Subscapularis tears are becoming increasingly recognized as a cause of shoulder pain and disability. However, identifying the subscapularis tendon stump is often difficult during repair of chronic, retracted subscapularis tears that are scarred to the deltoid fascia. The authors have found the “comma sign,” an arc formed by a portion of the superior glenohumeral ligament/coracohumeral ligament complex, to be a useful marker of the superolateral corner of the torn subscapularis tendon.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 334–337     

Patterns of strain and the determination of the safe arc of motion after subscapularis repair—A biomechanical study

This study characterizes the strain patterns and safe arcs for passive range of motion (ROM) in the superior and inferior subscapularis tendon in seven cadaveric shoulders, mounted for controlled ROM, after deltopectoral approach to the glenohumeral joint, including tenotomy of the subscapularis tendon 1 cm medial to its insertion on the lesser tuberosity. The tenotomy was repaired with end‐to‐end suture in neutral rotation. Strain patterns were measured during passive ROM in external rotation (ER), ER with 30° abduction (ER+30), abduction, and forward flexion in the scapular plane (SP) before and after surgery. Percentages were calculated from 35 trials corresponding to five trials of each motion across seven specimens. With ER of 0?30°, 89% of trials of superior subscapularis tendon and 100% of trials of inferior subscapularis tendon achieved strains >3%, with very similar patterns noted in ER+30. In abduction of 0?90°, 5.8% of trials of superior and 85.3% of trials of inferior tendon achieved >3% strain. With passive ROM in SP, 26.5% of trials reached 3% strain in superior tendon compared to 100% in inferior tendon. Strain patterns in abduction and SP differed significantly (p < 0.001). Selective tenotomy and repair of the superior subscapularis tendon with open reparative or reconstructive shoulder procedures, when feasible, may be favorable for protected early passive ROM and rehabilitation postoperatively. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:518–524, 2016.

     

Glenohumerale Arthrolyse der Omarthroseschulter bei anatomischer Schulterprothesenimplantation

Aim of the operation

Pain reduction and improvement of range of motion.

Indications

Primary and secondary osteoarthritis, unsuccessful conservative treatment, limited range of motion with capsular contraction.

Contraindications

General contraindications for anatomical total shoulder arthroplasty. Instability arthritis without capsular contraction.

Operative technique

Deltopectoral approach. Detachment and release of the subscapularis tendon at the lesser tuberosity, incision of the anterior and inferior humeral sided capsule and osteophyte removal, humeral head resection and stem preparation. Glenoid exposure, capsular an labral resection. Glenoid surface preparation and prosthetic component implantation. Anatomical placement of the the humeral head without overstuffing. Implantation of the final humeral stem. Transosseous refixation of the subscapularis tendon. Wound closure.

Follow-up treatment

Abduction brace for 4 weeks. Assisted motion starting the first postoperative day during the first 6 weeks: anteversion/ retroversion 90-0-0°, abduction/ adduction 90-0-20°, internal/external rotation 90-0-individual limitation. Subsequent development of full range of motion.

Results

In 2009 and 2010 anatomical total shoulder arthroplasty with glenohumeral arthrolysis was performed in 53 cases. At an average follow up of 32 months the Constant score and range of motion improved significantly. The complication rate was 9%.     

Tears of the supraspinatus tendon associated with "hidden" lesions of the rotator interval

Exploration of the rotator interval during repair of 116 apparently "isolated" supraspinatus tendon lesions have revealed "hidden lesions" of the coracohumeral ligament, the superior glenohumeral ligament, and the superior portion of the subscapularis tendon in 19 cases. Epidemiologic characteristics were comparable with other series with the exception of involvement of the dominant shoulder in 95%. Arthroscopic computed tomography documented the lesion in 85% of the cases. At surgery the superficial layer of the coracohumeral ligament was always intact. After splitting of the rotator interval the lesion was visible and consisted of a local disinsertion of the common insertion of the superior glenohumeral ligament and the coracohumeral ligament and the deep superior fibers of the subscapularis tendon. It measured 1 to 2 cm in the superior-inferior direction. The biceps tendon was ruptured in 2 cases, subluxated in 14, and in its normal position in 5. The treatment consisted of intraosseous reinsertion of the supraspinatus tendon, recentering of the biceps, and reinsertion of the torn structures to reconstruct a functional pulley system. The patients have been reviewed with a mean follow-up of 20 months (range 12 to 36 months). A secondary rupture of the long head of the biceps has been observed in 25% of the cases after recentering of the tendon.     

Repair of tears of the subscapularis

BACKGROUND: Rotator cuff tears involving the subscapularis are less common than those involving the superior aspect of the rotator cuff. The purpose of the present study was to report the results of repair of isolated tears of the subscapularis. METHODS: The records on eighty-four shoulders that had undergone open repair of the subscapularis tendon were reviewed. The mean age of the patients at the time of surgery was 53.2 years. The mean interval from the onset of symptoms to the time of surgery was 12.5 months. Fifty-seven tears were traumatic, and twenty-seven were degenerative. Twenty-three tears involved the superior one-third of the subscapularis tendon, forty-one tears involved the superior two-thirds, and twenty tears were complete. Fifty-four shoulders had a dislocation or subluxation of the long head of the biceps tendon, and ten shoulders had a rupture of the long head of the biceps tendon. Forty-eight shoulders underwent concomitant biceps tenodesis, thirteen shoulders underwent concomitant biceps tenotomy, and four shoulders underwent concomitant recentering of the biceps. Patients were evaluated clinically and radiographically at a mean of forty-five months (range, twenty-four to 132 months) postoperatively. RESULTS: The mean Constant score increased from 55.0 points preoperatively to 79.5 points postoperatively. Seventy-five patients were satisfied or very satisfied with the result. Preoperatively, four shoulders had mild glenohumeral arthritis. Postoperatively, twenty-five shoulders had mild glenohumeral arthritis and two shoulders had moderate glenohumeral arthritis. Tenodesis or tenotomy of the biceps tendon at the time of subscapularis repair was associated with improved subjective and objective results, independent of the preoperative condition of the biceps tendon. CONCLUSIONS: Repair of isolated subscapularis tears yields acceptable improvement in shoulder function in selected patients. Additionally, the results of the present study support routine tenodesis or tenotomy of the long head of the biceps tendon at the time of subscapularis repair.     

The “Subscapularis-Sparing” Approach: A New Mini-Open Technique to Repair a Humeral Avulsion of the Glenohumeral Ligament Lesion

Anterior approaches to the shoulder involve partial or complete detachment of the subscapularis muscle. We have developed a new technique that permits adequate access to the humeral attachment of the inferior glenohumeral ligament (IGHL) without any detachment of the subscapularis, and have used this to successfully repair humeral avulsions of glenohumeral ligament lesions. Preliminary diagnostic arthroscopy using air insufflation of the glenohumeral joint is used to identify and grade the lesion. A 1-inch axillary incision is used to access the subscapularis tendon through the deltopectoral approach. Thereafter, anatomic landmarks are identified to expose the lateral aspect of the inferior border of the subscapularis muscle. Blunt dissection is used to separate the musculocapsular plane, and the subscapularis is retracted in an anterosuperior direction. Adequate exposure for visualization and repair of the avulsed IGHL is possible in a majority of cases where this approach is attempted. The use of arthroscopic instruments and suture anchors facilitates suture passage through the mid and posterior regions of the IGHL. If exposure is inadequate, the approach can be easily converted to a conventional L-shaped tenotomy approach through the lower or upper region of the subscapularis.     

The impact of subscapularis integrity on functional outcome in reverse total shoulder arthroplasty utilizing a 135˚ stem

BackgroundReverse shoulder arthroplasty (RSA) predictably restores overhead function and provides pain relief in patients with glenohumeral arthritis and rotator cuff deficiency. Implant design with an anatomic inclination angle of 135˚ may provide an advantage in the healing rates of subscapularis tendon (SST) repairs. The purpose of this study was to use ultrasound to evaluate the subscapularis repair healing rate, and secondarily, to compare outcomes between healed and non-healed SSTs, in patients undergoing RSA with a 135˚ inclination angle.MethodsA prospectively collected, multicenter shoulder arthroplasty registry was queried to identify patients undergoing RSA with a 135˚ inclination stem with a minimum of 1 year follow-up. Ultrasound analysis was performed at final follow-up to assess subscapularis integrity. Exclusion criteria included RSA for fracture, fracture sequelae or failed prior arthroplasty. Outcome measures included American Shoulder and Elbow Surgeons score (ASES), Western Ontario Osteoarthritis of the Shoulder (WOOS), Single Anatomic Numeric Evaluation (SANE), and Constant scores. Additionally, subscapularis functional assessments included range of motion, belly-press and shirt-tuck tests. Statistical analysis was performed using ANOVA, Chi-square, and student t-tests with SPSS. Results were considered significant at P < .05.ResultsSeventy-eight patients meeting the inclusion criteria were identified from the registry, however, only seventy-five patients had ultrasound and healing data. The subscapularis was repaired in 60 patients and healing via ultrasound was noted in 56.7% (34/60). In most cases, a subscapularis peel was performed, with lesser tuberosity osteotomy performed in 9.38% of cases. Patients whose subscapularis was repaired were found to be older (72.2 vs. 64.9, P < .001) and the majority of patients with an unrepaired subscapularis were male (13/15, 86.7% unrepaired vs. 27/60, 45.0% repaired). Both healed and non-healed patient cohorts showed statistical improvement in all pain and functional outcome scores from their baselines. However, there were no significant differences in outcome scores between healed and non-healed SST. With regards to SST repair, only overall WOOS (Δ+15.62, P = .049) and physical component of the WOOS score (Δ+15.97, P = .040) were higher in patients with nonrepaired SST. There was no correlation between the ability to perform a belly-press or shirt-tuck test and subscapularis repair or evidence of radiographic healing. Patients who did not have their subscapularis repaired demonstrated greater passive external rotation at the side from 31° to 51° (P = .044). A significant increase in passive forward flexion was noted in patients with healed subscapularis from 117° to 135° (P = .042). There was no statistical difference in active range of motion between either the repaired/nonrepaired or healed/non-healed cohorts.ConclusionOur study demonstrates a healing rate of 57% following repair in patients undergoing RSA with a 135˚ angle. Standardized outcome measures overall demonstrated no difference between patients with a healed subscapularis compared to those with a non-healed or unrepaired subscapularis.Level of EvidenceIV, case series, treatment study.     

Effect of the neck-shaft angle on stability in the onlay type of reverse shoulder arthroplasty: a cadaveric study

BackgroundAlthough reverse shoulder arthroplasty (RSA) has been indicated for treating patients suffering from cuff tear arthropathy, instability is a severe complication. The relationship between the humeral neck-shaft angle and joint stability in RSA as well as the clinical effect of subscapularis tendon repair on postoperative stability after RSA remain controversial. This study is primarily aimed to investigate the relationship between humeral neck-shaft angle and stability using the onlay type of RSA with preserved shoulder girdle muscles using fresh frozen cadavers. Moreover, we aimed to investigate the effect of subscapularis tendon repair after RSA placement.MethodsAn onlay type RSA of not-lateralized glenosphere in a massive rotator cuff tear model with preserved shoulder component muscles was placed on 7 fresh frozen cadavers, and traction tests were performed to dislocate by changing the neck-shaft angle of the stem to 135°, 145°, and 155°. The anterior dislocation force (DF) was evaluated in 6 patterns as follows: 2 patterns at 30° and 60° of abduction and 3 patterns at 30° of internal rotation, in neutral rotation, and 30° of external rotation. DF was recorded at neck-shaft angles of 135°, 145°, and 155° and with and without subscapularis tendon repair.ResultsAt 30° abduction, DF was significantly higher at a neck-shaft angle of 155° regardless of the rotational position (P < .05), and at abduction 60°, there was no difference in DF according to any rotational position and any neck-shaft angle. Regardless of the neck-shaft angle, the DF was significantly higher at 60° abduction than at 30° abduction (P < .05). Furthermore, the DF was significantly higher with subscapularis tendon repair (P < .01).ConclusionOur results showed some relationship between humeral neck-shaft angle and stability in the onlay type of RSA with preserved shoulder component muscles using fresh frozen cadavers. Moreover, a neck-shaft angle of 155° showed the highest anterior DF among neck-shaft angles of 135° and 145° at 30° abduction, and there was no difference at abduction 60° among any neck-shaft angle. Furthermore, subscapularis tendon repair also contributed to anterior stability.     

Subscapularis,medial, and lateral head coracohumeral ligament insertion anatomy: Arthroscopic appearance and incidence of “hidden” rotator interval lesions

Purpose: The purpose of this study was to document the incidence of lesions of the rotator interval, illustrate the arthroscopic appearance of subtle differences in these lesions, and discuss how various lesions may affect biceps tendon stability in the bicipital groove. Type of Study: A Data Registry has been used in my office since 1995 (Microsoft Office Access). This study reports on the results of a retrospective database “query” of the prospectively entered data from 1995 to 1998. Thus, by default, the format of this study is a consecutive sample. Only patients with a disruption of rotator cuff tendons, labrum and/or gleno-coracohumeral ligaments are included by study design. Methods: This study has identified and reports on 46 arthroscopically identified subscapularis tears, 25 “hidden” rotator interval lesions (SGHL/MCHL complex) and 6 SGHL/CHL complex plastic deformation lesions in 165 patients undergoing shoulder arthroscopy for conditions ranging from anterior instability to rotator cuff tears. Arthroscopically identified lesions include partial or complete disruptions of the subscapularis tendon, disruptions of the superior glenohumeral/medial head coracohumeral ligament complex (SGHL/MCHL), disruptions of the lateral head coracohumeral ligament (LCHL), and various combinations of the above. Results: The incidence rate of subscapularis tendon involvement in 165 arthroscopically treated shoulder patients was 27%. The incidence rate of subscapularis tendon disruptions with rotator cuff pathology was 35%. The incidence rate of SGHL/MCHL lesions (tear or stretch) in 165 arthroscopically treated shoulder patients was 18%. The incidence rate of SGHL/MCHL tears in 165 arthroscopically treated shoulder patients was 15%. Forty-seven percent of all subscapularis tears involved the SGHL/CHL complex. Ten percent of all rotator cuff tears involving the supraspinatus tendon involved the LCHL. Conclusions: This study has recorded the incidence of lesions of the subscapularis, SGHL/MCHL complex and/or the LCHL, and combinations thereof in degenerative cuff and instability patients. Primary lesions of the rotator interval can occur and regardless of the associated pathology, and if these lesions are not repaired, biceps tendon subluxation may exist.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 2 (February), 2001: pp 173–180     

The influence of rotator cuff disease on the results of shoulder arthroplasty for primary osteoarthritis: results of a multicenter study

BACKGROUND: Rotator cuff disease is uncommon in primary glenohumeral osteoarthritis. Consequently, the prognostic implications of rotator cuff disease in patients undergoing prosthetic replacement for the treatment of primary glenohumeral osteoarthritis are uncertain. The purpose of this study was to report the effects of the condition of the supraspinatus tendon and the rotator cuff musculature on the results of shoulder arthroplasty in the treatment of primary osteoarthritis. METHODS: Five hundred and fifty-five shoulders in 514 patients who had an arthroplasty for the treatment of primary glenohumeral osteoarthritis as part of a multicenter study were evaluated. Forty-one shoulders had a partial-thickness tear of the supraspinatus, and forty-two had a full-thickness tear. Ninety shoulders had moderate (stage-2) fatty degeneration of the infraspinatus, and nineteen had severe (stage-3 or 4) degeneration. Eighty-four shoulders had moderate fatty degeneration of the subscapularis, and fifteen had severe degeneration. The influence of the condition of the supraspinatus tendon and the infraspinatus and subscapularis musculature on the postoperative outcome was evaluated with respect to the scores according to the system of Constant and Murley, active mobility, subjective satisfaction, radiographic result, and rate of complications. RESULTS: The shoulders were evaluated at a mean of 43.1 months postoperatively. With the numbers available, supraspinatus tears were not found to influence the postoperative outcome with respect to the total Constant score, active mobility, subjective satisfaction, radiographic result, or rate of complications. Additionally, the treatment of these tears did not markedly influence the outcome parameters. Conversely, both shoulders with moderate fatty degeneration and those with severe degeneration of the infraspinatus were associated with poorer results than those with no degeneration with respect to the total Constant score (p < 0.0005), active external rotation (p < 0.0005), active forward flexion (p = 0.001), and subjective satisfaction (p = 0.031). Similar although less dramatic results were seen with fatty degeneration of the subscapularis. CONCLUSIONS: This study demonstrates that minimally retracted or nonretracted rotator cuff tears that are limited to the supraspinatus tendon do not appreciably affect most shoulder-specific outcome parameters in shoulder arthroplasty performed for the treatment of primary osteoarthritis. Conversely, fatty degeneration of the infraspinatus and, less importantly, subscapularis musculature adversely affects many of these parameters.     

The influence of deltoid tensioning on functional outcomes following reverse shoulder arthroplasty

BackgroundWe aimed to investigate the relationship between functional outcomes and radiological and clinical measurements (based on deltoid moment arm length measurements) of reverse total shoulder arthroplasty (RTSA) performed in patients for irreparable rotator cuff tears.MethodsThirty-eight patients who underwent RTSA after irreparable rotator cuff tears between 2016 and 2019 were included in the study. Patients with primary osteoarthritis, rheumatoid arthritis, or post-traumatic RTSA were excluded from the study. The patients were evaluated functionally using the range of motion, Quick DASH, and Constant Scores (CS). Deltoid lengthening was measured both clinically by the difference in upper extremity length (dUEL) and radiologically by the acromiohumeral distance (AHD) and deltoid lever length (DLL). AHD was measured with true anteroposterior radiographs and ultrasound guidance.ResultsThe mean age of the patients was 66.39 ± 7.92 (range, 49–83) years. Of 38 patients, 31 (81.57%) were female and 7 (18.43%) were male. The mean follow-up durations were 26.43 ± 17.05 (range, 12–58) months. The mean active anterior elevation (AAE), abduction (AAB), and external rotation (AER) increased from 57.32°, 41.25°, and 22.32° preoperatively to 149°, 110°, and 34° at the last follow-up, respectively. Preoperatively, the mean QuickDASH score was 58.04, and at the last follow-up, it was 38.19. The mean Constant Score rose from 24.75 preoperatively to 60.64 at the last follow-up. The AHD, DLL, and dUEL mean values were 2.346, 1.89, and 1.746 cm, respectively. There was a significant relation between the DLL and the AAE (P < .01).ConclusionOptimizing deltoid tension plays an essential role in regaining function, and this study demonstrates that lengthening the deltoid increases the patient’s ability to elevate anteriorly, likely by recreating the force-length relationship of the deltoid muscle.     

Reconstruction of the antero-superior shoulder capsule with the subscapularis tendon: A case report

A 14-year-old boy presented with recurrent, anteroinferior, and multidirectional instability of his dominant shoulder. Examination with the patient under anesthesia demonstrated marked anterior and inferior translation when drawer testing was performed in adduction; however, abduction of the shoulder reduced the magnitude of humeral head translation in both these directions. Arthroscopy and open surgical dissection revealed the absence of any capsuloligamentous structures above the anterior band of the inferior glenohumeral ligament complex. This superior capsular defect could not be closed by a capsular shift procedure; therefore it was reconstructed with a portion of the subscapularis tendon. This case provides a clinical correlation of capsular anatomy with laxity on drawer testing. The glenohumeral laxity documented on examination with the patient under anesthesia supports experimental ligament-cutting studies that suggest the inferior glenohumeral ligament complex is the important stabilizer in abduction, whereas the superior and middle glenohumeral ligaments are more important in adduction.     

Biomechanical analysis of the subscapularis,infraspinatus and teres minor length and moment arm after reverse shoulder arthroplasty: a cadaveric study

BackgroundReverse shoulder arthroplasty (RSA) affects the length and moment arm of the deltoid and rotator cuff. Currently, RSA is commonly considered for cuff-intact conditions, such as primary glenohumeral osteoarthritis. As such, understanding the effect of contemporary lateralized designs on the rotator cuff is paramount. The purpose of this study was to determine changes in length and moment arm of the subscapularis, infraspinatus and teres minor with implantation of one of 3 RSA designs.MethodsA previously validated model was used in 6 hemi-toraces with the shoulder attached. Suture lines were run through pneumatic cylinders from the insertion to the origin of 10 muscles to apply a constant, stabilizing load. Electromagnetic tracking sensors were fixed to the thorax, scapula, and humerus to record 3-dimensional kinematics. Coordinate systems were established according to ISB recommendations. The origin and insertion of the subscapularis, infraspinatus and teres minor were digitized and tracked. Testing consisted of manually rotating the humerus through 5 cycles of its internal-external rotation arc. Kinematic data was collected at 120 Hz. Testing was performed in 3 positions of abduction: 0°, 30°, and 60°. After testing the intact shoulder, RSA was performed using 3 different configurations: an onlay 135-degree humeral component matched with a 2-mm lateralized glenosphere, the same humeral component with a 6-mm lateralized glenosphere, and an inlay 135-degree humeral component matched with a 10 mm lateralized glenosphere. Minimal muscle operative lengths, maximal muscle operative lengths, and muscle moment arms were computed.ResultsWhen compared with the native shoulder, all 3 configurations of RSA resulted in statistically significant increases in both the minimal and maximal operative lengths of the subscapularis in all abduction positions. The teres minor only showed a statistically significant increase in minimal and maximal length at 60° of abduction. The infraspinatus showed a statistically significant increase in tendon excursion at 0° and 30° of abduction. In 40° of abduction and 40° of internal rotation, all RSA configurations translated in a decreased subscapularis internal rotation moment arm. On the contrary, RSA increased the external rotation moment arm of the infraspinatus in neutral rotation and 0° of abduction.ConclusionImplantation of contemporary lateralized RSA implants led to increased length of the subscapularis to a greater extent than the increased length experienced by the infraspinatus and teres minor. The moment arm of the subscapularis decreased, whereas the moment arm of the teres minor in neutral rotation with the arm in abduction increased.Level of EvidenceLevel III; Basic Science, Biomechanics Study     

The rotator interval: anatomy, pathology, and strategies for treatment

Over the past two decades, it has become accepted that the rotator interval is a distinct anatomic entity that plays an important role in affecting the proper function of the glenohumeral joint. The rotator interval is an anatomic region in the anterosuperior aspect of the glenohumeral joint that represents a complex interaction of the fibers of the coracohumeral ligament, the superior glenohumeral ligament, the glenohumeral joint capsule, and the supraspinatus and subscapularis tendons. As basic science and clinical studies continue to elucidate the precise role of the rotator interval, understanding of and therapeutic interventions for rotator interval pathology also continue to evolve. Lesions of the rotator interval may result in glenohumeral joint contractures, shoulder instability, or in lesions to the long head of the biceps tendon. Long-term clinical trials may clarify the results of current surgical interventions and further enhance understanding of the rotator interval.