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.     

Latissimus-dorsi-Transfer bei nichtrekonstruierbarem Rotatorenmanschettendefekt

Objective

Improvement of glenohumeral dynamic centering and active external rotation by a transfer of the latissimus dorsi tendon to the greater tuberosity or the lateral proximal humerus.

Indications

Irreparable posterosuperior rotator cuff tears.

Contraindications

Cuff tear arthropathy, subscapularis tendon tear, deltoid insufficiency, palsy of the axillary nerve.

Surgical technique

Diagnostic arthroscopy in lateral decubitus position. Placement of suture through the biceps tendon and supragleonidal tenotomy. Posterior approach. Preparation and mobilization of a pedicled latissimus dorsi flap. Second anterior incision with delta split. Debridement of the torn rotator cuff. Insertion of suture anchors in the greater tuberosity. Passing of the muscle flap inferior to the posterior deltoid and fixation with suture anchors to the greater tuberosity (where applicable suturing with remaining rotator cuff tissue).

Postoperative management

Immobilization in a thorax abduction cast for 6?weeks. Passive exercises out of the cast (IR/ER 0-0-free and ABD/ADD free-45-0°). Active assistive exercises from week?4 postoperatively. Stepwise increase of passive range of motion from week?7. Unlimited active range of motion from week?10.

Results

After an average follow-up of 57.6 (SD?27.5) months 17?patients were examined clinically. The average age at time of surgery was 55.6 (SD?7.7) years. At follow-up the patients showed an average Constant score of 64.4?points (SD?17.4). The active external rotation in 0° abduction was 16° (SD?17). The 4?patients (23%) with a sonographically-detected retear of the latissimus flap presented worse clinical results.     

Management of the subscapularis contracture during shoulder arthroplasty for primary glenohumeral arthritis

Aim To evaluate the safety and effectiveness of a particular subscapularis release in shoulder arthroplasty for primary glenohumeral arthritis. Materials and methods Twenty-eight patients (19F, 9M) underwent shoulder arthroplasty for primary glenohumeral arthritis. Preoperative average Constant Score (CS) was 31.2 points (range 14–52), active anterior elevation (AAE) 92° (30–100°) and active external rotation (AER) 11° (−40 to 20°). During arthroplasty for subscapularis contracture, patients underwent subscapularis release freeing the superior tubular tendon (STT) with a section of the coracohumeral ligament (CHL) and the superior glenohumeral ligament (SGHL) and a deep release consisting of a section of the middle glenohumeral ligament (MGHL), very close to the glenoid labrum, and the inferior glenohumeral ligament (IGHL). An anatomic study was performed on 13 cadavers, verifying the structure of subscapularis tendon and its relationship with the capsule, the surrounding ligaments and the axillary nerve. Moreover, after having placed traction sutures on the subscapularis tendon, its lengthening was measured after STT release alone and after STT and deep release. The complete absence of neurological and vascular lesions was also verified. Results Average follow-up: 2.9 years. Postoperative mean CS was 70.5 (p〈0.005), with an absolute gain of 39.1. AAE increased from 92° to 142° (p=0.001) while AER increased from 8° to 48° (p=0.002). At the last follow-up, 19 patients (67.8%) were very satisfied, 5 patients (17.8%) were satisfied, 3 patients (10.7%) partially satisfied and 1 patient (3.5%) unsatisfied. In the anatomic control, the average lengthening of subscapularis tendon was 0.9 cm after STT release alone and 2.5 cm after STT and deep release. No vascular and neurological lesions were observed. Conclusions The subscapularis release during shoulder arthroplasty is extremely important to obtain the proper balance between anterior and posterior soft tissues and to achieve an optimal range of motion and joint stability. An adequate anatomical dissection could give good tendon mobilisation and lengthening, necessary for a good repair, and lead to a recovery of the range of motion, particularly for external rotation.     

Structural properties of the subscapularis tendon.

The subscapularis muscle is an important mover and stabilizer of the glenohumeral joint. The purpose of this study was to measure regional variations in the structural properties of the subscapularis tendon in two joint positions. Subscapularis tendons from cadaveric shoulders were divided into four sections superiorly to inferiorly and tested to failure at 0 or 60 degrees of glenohumeral abduction. Arm position had a significant influence on stiffness in the inferior and superior portions (p < 0.05). The inferior region showed a higher stiffness in the hanging-arm position (0 degrees) than at 60 degrees of abduction (27.4+/-17.7 compared with 9.5+/-5.9 N/mm). Meanwhile, stiffness of the superior portion was higher at 60 degrees of abduction than in the hanging-arm position (208.7+/-60.9 compared with 147.2+/-32.3 N/mm). In the hanging-arm position (0 degrees) and at 60 degrees of abduction, the superior and midsuperior portions failed at significantly higher loads (superior: 623.2+/-198.6 and 478.2+/-206.6 N at 0 and 60 degrees of abduction, respectively; midsuperior: 706.2+/-164.6 and 598.4+/-268.4 N, respectively) than did the inferior portion (75.1+/-54.2 and 30.3+/-13.0 N, respectively). Likewise, stiffness of the superior and midsuperior portions was significantly higher than that of the inferior region in both positions. Higher stiffness and ultimate load in the superior tendon region may explain the infrequent extension of rotator cuff tears into the subscapularis tendon. Conversely, the significantly lower ultimate load and stiffness in the inferior tendon region could facilitate anterior dislocation of the humeral head when this portion stabilizes the joint in a dislocated position. Therefore, repair of torn inferior portions of the subscapularis tendon should be considered in surgery for glenohumeral instability.     

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     

Pressure between the humeral head and the subscapularis tendon after the modified Boytchev procedure

The pressure between the humeral head and the subscapularis tendon was determined in 32 patients who had recurrent anterior shoulder dislocations. These patients' pressures were measured during a modified Boytchev procedure both before and after transposition of the conjoined tendon, and they were remeasured at the time of screw removal, performed at a mean of 13 months after the initial surgery. The mean clinical follow-up period was 31 months. A micro-tip catheter transducer was inserted into the glenohumeral joint between the humeral head and the subscapularis tendon. Pressures were measured at particular degrees of motion for two positions: passive external rotation of the arm at the side at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 60 degrees and passive external rotation at the 90 degrees abducted position at 0 degrees, 30 degrees, 60 degrees, and 90 degrees. The pressures were statistically significantly higher after the conjoined tendon transfer at all measured degrees of motion in the two positions. The pressures at the time of screw removal were not statistically significantly different from those seen after the tendon transfer during external rotation at 90 degrees of abduction. The modified Boytchev procedure increases the pressure between the humeral head and the subscapularis tendon. We suspect that this increased pressure increases proprioceptive stimuli in the subscapularis tendon and thus accelerates the protective reflex needed to prevent shoulder dislocation.     

The effect of subscapularis tenotomy in athletes operated on for recurrent anterior shoulder dislocation

Purpose

Some authors consider preservation of the subscapularis tendon as one of the most important elements for a successful long-term outcome in patients operated on with open capsulorrhaphy for recurrent anterior shoulder dislocation. The purpose of this study was to evaluate whether vertical tenotomy of the subscapularis tendon might affect internal rotation strength recovery in patients operated on with open capsulorrhaphy for recurrent anterior shoulder dislocation.

Methods

Ninety-six patients were retrospectively followed up at a mean of 72.5 months. They underwent clinical evaluation, Rowe and Walch–Duplay scoring scales, the Visual Analog Scale (VAS), and dynamometric measurements (side-to-side) of internal and external rotation, forward elevation, and abduction. All patients were athletes: 25% were practising risk-free sports, 44% contact sports, 14.5% sports with cocking of the arm, and 14.5% high-risk sports activities.

Results

Five (5.2%) recurrences were registered, and all patients returned to pre-operative sports activity. The Rowe score was 98.12, the Walch–Duplay score 92.25, and the VAS score 0.1. Dynamometric assessment showed no significant differences (side-to-side) in internal rotation (p = 0.34), external rotation (p = 0.9), flexion (p = 0.7), and abduction (p = 0.7). Dominant arms showed better results than non-dominant arms (p < 0.01).

Conclusion

Complete tenotomy of the subscapularis tendon does not seem to negatively affect internal rotation strength recovery or external rotation movement in athletes.

     

The biomechanical role of the subscapularis in latissimus dorsi transfer for the treatment of irreparable rotator cuff tears

Inferior functional results of latissimus tendon transfer for the treatment of irreparable rotator cuff tears have been reported in the presence of a subscapularis tendon tear. A biomechanical or experimental explanation for the necessity of an intact subscapularis is unavailable. It was, therefore, the purpose of this investigation to study the biomechanical role of the subscapularis in the treatment of a posterosuperior rotator cuff tear with latissimus dorsi transfer. A biomechanical cadaveric model was developed to reproduce glenohumeral motion patterns created by loading of the transferred latissimus dorsi tendon with and without simultaneous action of the subscapularis muscle. Significant differences could be demonstrated not only for translation but also for rotation of the humeral head depending on subscapularis action. In the neutral and in the abducted/externally rotated position of the arm, anterior translation and dislocation of the joint were encountered without subscapularis action. Our results provide evidence that motion patterns of the humeral head are significantly altered in the absence of the stabilizing effect of the subscapularis muscle. The inferior functional results of latissimus dorsi transfer in the presence of subscapularis dysfunction are explained by the loss of centering of the humeral head upon abduction and elevation if subscapularis function is deficient.     

The glenohumeral micromotion and influence of the glenohumeral ligaments during axial rotation in varying abduction angle

BackgroundThe patients with shoulder instability or disorders in overhead athletes have been considered to have an abnormal micromotion at the glenohumeral joint. However, the normal range of the micromotion has not been available during axial rotation with various abduction angles, especially above 90° abduction. This study aimed to investigate the glenohumeral translation and influence of the glenohumeral ligaments during axial rotation with up to maximum abduction.MethodsFourteen healthy volunteers performed active axial rotations at 0°, 90°, 135°, and maximal abduction angles. The positions of the humeral head center relative to the glenoid at maximally external, neutral, and maximally internal rotations (ER, NR, IR, respectively) for each abduction angle were evaluated using two- (2D) and three-dimensional (3D) shape matching registration techniques. The shortest pathway and its length between the origin and insertion of the superior, middle, and inferior glenohumeral ligaments (SGHL, MGHL, and IGHL, respectively) were calculated for each position.ResultsThe glenohumeral joint showed 3.1 mm of superoinferior translation during axial rotation at 0° abduction (P < 0.0001), and 2.6 mm and 4.5 mm anteroposterior translation at 135° and maximal abduction (P < 0.0001), respectively. The SGHL and MGHL reached a maximum length at ER with 0° abduction, and the anterior and posterior bands of the IGHL reached a maximum at ER with 90° abduction and IR with 0° abduction.ConclusionsThese findings indicated that the SGHL played a role as an inferior suppressor at 0° abduction, while the anterior band of IGHL played a role as an anterior stabilizer at 90° abduction. Every glenohumeral ligament did not get taut and the anteroposterior translation became greater with increasing abduction angle, above 90°. These results could be used as a reference when comparing with the pathological shoulders in the future study.     

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     

Subscapularis motor point block for spastic shoulders in patients with cervical cord injury

Study design: Case series.Objectve: The objective was to study the effect of phenol blocks to the motor points of the subscapularis muscle in patients with cervical cord injury (CCI).Setting: Spinal cord injury units of a national hospital in Tokyo.Methods: The participants were seven patients with traumatic CCI, mean age 55.8 years (SD4.0), whose injury level were at the fifth cervical level and the American Spinal Injury Association (ASIA) impairment scale was A in 2, C in 1 and D in 4. They were at least 5 months post-acute injury, and complained of pain and limited range of motion (ROM) of their shoulder joint that were unresponsive to usual rehabilitative interventions and medications. Before and after the phenol block to the motor points of the subscapularis muscle, we compared passive and active ROM of the shoulder (flexion, abduction and external rotation), spasticity of the subscapularis as assessed with the modified Ashworth scale, pain as evaluated with a visual analog scale, and eating item of the Functional Independence Measure.Results: There were significant improvements in passive ROM in flexion (23.7 degrees ), abduction (19.4 degrees ) and external rotation (16.8 degrees ; P<0.05). Visual analog scale for shoulder pain was reduced from 6.0 to 3.4 (P<0.05). The modified Ashworth scale for shoulder spasticity, however, did not significantly change. The eating Functional Independence Measure item score improved significantly (P<0.05).Conclusions: This study suggests that subscapularis motor point block for pain and limited ROM with spastic shoulder is a useful technique in patients with CCI.Spinal Cord (2009) 47, 249-251; doi:10.1038/sc.2008.122; published online 30 September 2008.     

Bridging suture makes consistent and secure fixation in double-row rotator cuff repair

Background

Inconsistent tension distribution may decrease the biomechanical properties of the rotator cuff tendon after double-row repair, resulting in repair failure. The purpose of this study was to compare the tension distribution along the repaired rotator cuff tendon among three double-row repair techniques.

Latissimus dorsi transfer for primary treatment of irreparable rotator cuff tears

Transfer of the musculotendinous unit of the latissimus dorsi was performed in seven patients (5 men and 2 women, with a mean age of 57 years) with irreparable rotator cuff tear who had had no previous surgery for cuff repair. Preoperatively, the mean active shoulder motion was 86° in flexion, 74° in abduction and 22° in external rotation. One patient had a positive lift-off test. The average preoperative Constant and Murley score was 44%. Diagnosis of irreparability of the cuff leasion was made preoperatively only in one case. In the remaining patients, the preoperative data only led to suspect that the tear was irreparable. At surgery, all patients had an irreparable tear of the superoinferior portion of the cuff and one patient also had a tear of the subscapularis tendon. In all cases the latissimus dorsi tendon was inserted to the greater tuberosity and, in four cases, to the subscapularis tendon; in three patients it was sutured to the bicipital tendon. Postoperatively all patients had relief of shoulder pain. The mean improvement in active flexion, abduction and external rotation was, respectively, 39°, 29° and 10°: At the latest follow-up, the average Constant and Murley score was 64%. The results of surgery were rated as excellent in three cases, good in two, fair in one and poor in one. All patients but one returned to preoperative work. Transfer of the latissimus dorsi muscle is an effective procedure for patients in middle or early elderly age who have an irreparable tear of the supraspinatus and infraspinatus tendons. Received: 18 December 2001/Accepted: 4 January 2002     

Effect of rotator interval closure on glenohumeral stability and motion: a cadaveric study

The effect of rotator interval closure, which is performed as an adjunct to arthroscopic stabilization of the shoulder, has not been clarified. Fourteen fresh-frozen cadaveric shoulders were used. The position of the humeral head was measured using an electromagnetic tracking device with the capsule intact, sectioned, and imbricated between the superior glenohumeral ligament and the subscapularis tendon (SGHL/SSC closure) or between the superior and middle glenohumeral ligaments (SGHL/MGHL closure). The direction of translational loads (10, 20, and 30 N) and arm positions were (1) anterior, posterior, and inferior loads in adduction; (2) anterior load in abduction/external rotation in the scapular plane; and (3) anterior load in abduction/external rotation in the coronal plane. The range of motion was measured using a goniometer under a constant force. Both methods reduced anterior translation in adduction. Only SGHL/MGHL closure reduced anterior translation in abduction/external rotation in the scapular plane and posterior translation in adduction. Both methods reduced the range of external rotation and horizontal abduction. Rotator interval closure is expected to reduce remnant anterior/posterior instability and thereby improve the clinical outcomes of arthroscopic stabilization procedures.     

Moment arms of the shoulder muscles during axial rotation

The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub‐regions crossing the glenohumeral joint in axial rotation of the humerus during coronal‐plane abduction and sagittal‐plane flexion. The tendon‐excursion method was used to measure instantaneous muscle moment arms in eight entire upper‐extremity cadaver specimens. The results showed that the inferior subscapularis was the largest internal rotator; its rotation moment arm peaks were 24.4 and 27.0 mm during abduction and flexion, respectively. The inferior infraspinatus and teres minor were the greatest external rotators; their respective rotation moment arms peaked at 28.3 and 26.5 mm during abduction, and 23.3 and 22.1 mm during flexion. The two supraspinatus sub‐regions were external rotators during abduction and internal rotators during flexion. The latissimus dorsi and pectoralis major behaved as internal rotators throughout both abduction and flexion, with the three pectoralis major sub‐regions and middle and inferior latissimus dorsi displaying significantly larger internal rotation moment arms with the humerus adducted or flexed than when abducted or extended (p < 0.001). The deltoid behaved either as an internal rotator or an external rotator, depending on the degree of humeral abduction and axial rotation. Knowledge of moment arm differences between muscle sub‐regions may assist in identifying the functional effects of muscle sub‐region tears, assist surgeons in planning tendon transfer surgery, and aid in the development and validation of biomechanical computer models. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:658–667, 2011     

Effect of glenohumeral abduction angle on the mechanical interaction between the supraspinatus and infraspinatus tendons for the intact,partial‐thickness torn,and repaired supraspinatus tendon conditions

Rotator cuff tears are difficult to manage because of the structural and mechanical inhomogeneity of the supraspinatus tendon. Previously, we showed that with the arm at the side, the supraspinatus and infraspinatus tendons mechanically interact such that conditions that increase supraspinatus tendon strain, such as load or full‐thickness tears, also increase infraspinatus tendon strain. This suggests that the infraspinatus tendon may shield the supraspinatus tendon from further injury while becoming at increased risk of injury itself. In this study, the effect of glenohumeral abduction angle on the interaction between the two tendons was evaluated for supraspinatus tendon partial‐thickness tears and two repair techniques. Principal strains were quantified in both tendons for 0°, 30°, and 60° of glenohumeral abduction. Results showed that interaction between the two tendons is interrupted by an increase in abduction angle for all supraspinatus tendon conditions evaluated. Infraspinatus tendon strain was lower at 30° and 60° than at 0° abduction angle. In conclusion, interaction between the supraspinatus and infraspinatus tendons is interrupted with increase in abduction angle. Additionally, 30° abduction should be further evaluated for management of rotator cuff tears and repairs as it is the angle at which both supraspinatus and infraspinatus tendon strain is decreased. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:846–851, 2010     

Does preoperative abduction value affect functional outcome of combined muscle transfer and release procedures in obstetrical palsy patients with shoulder involvement?

Background

Obstetric palsy is the injury of the brachial plexus during delivery. Although many infants with plexopathy recover with minor or no residual functional deficits, some children don't regain sufficient limb function because of functional limitations, bony deformities and joint contractures. Shoulder is the most frequently affected joint with internal rotation contracture causing limitation of abduction, external rotation. The treatment comprises muscle release procedures such as posterior subscapularis sliding or anterior subscapularis tendon lengtening and muscle transfers to restore the missing external rotation and abduction function.

Methods

We evaluated whether the preoperative abduction degree affects functional outcome. Between 1998 and 2002, 46 children were operated on to restore shoulder abduction and external rotation. The average age at surgery was 7.6 years and average follow up was 40.8 months. We compared the postoperative results of the patients who had preoperative abduction less than 90° (Group I: n = 37) with the patients who had preoperative abduction greater than 90° (Group II: n = 9), in terms of abduction and external rotation function with angle measurements and Mallet classification. We inquired whether patients in Group I needed another muscle transfer along with latissimus dorsi and teres major transfers.

Results

In Group I the average abduction improved from 62.5° to 131.4° (a 68.9° ± 22.9°gain) and the average external rotation improved from 21.4° to 82.6° (a 61.1° ± 23°gain). In Group II the average abduction improved from 99.4°to 140°(a40.5° ± 16°gain) and the average external rotation improved from 33.2°to 82.7° (a 49.5° ± 23.9° gain). Although there was a significant difference between Group I and II for preoperative abduction (p = 0.000) and abduction gain in degrees (p = 0.001), the difference between postoperative values of both groups was not significant (p = 0.268). There was also no significant difference between the two groups in the preoperative external rotation, the external rotation gain and the postoperative external rotation (p = 0.163, p = 0.181 and p = 0.803, respectively).

Conclusions

Obstetric palsy patients with shoulder sequela who had a preoperative abduction less than 90°hadas good functional results using latissimus dorsi, teres major muscle transfer and subscapularis muscle release as the patients who hada preoperative abduction greater than 90°.

     

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.     

Analysis of impingement-free range of motion of the glenohumeral joint after reverse total shoulder arthroplasty using three different implant models

Background

This study aimed to investigate impingement-free range of motion (ROM) of the glenohumeral joint following reverse total shoulder arthroplasty (RTSA) with three types of implant models using computational motion analysis.

Rotator interval dimensions in different shoulder arthroscopy positions: a cadaveric study

The rotator interval was defined as a triangular structure, where the base of the triangle was the coracoid base, the upper border was the anterior margin of the supraspinatus, and the lower border was the superior margin of the subscapularis muscle-tendon unit. We evaluated the rotator interval dimensions in 15 shoulders from 10 lightly embalmed adult cadavers in 3 shoulder arthroscopy positions: 0 degrees of abduction and 30 degrees of flexion (beach chair [BC]), 45 degrees of abduction and 30 degrees of flexion (lateral decubitus 1), and 70 degrees of abduction and 30 degrees of flexion (lateral decubitus 2). In each shoulder position, measurements were made in neutral rotation (NR), 45 degrees of external rotation (ER), and 45 degrees of internal rotation (IR). The coracoid base lengthened with IR in all positions and shortened in ER in the lateral decubitus position but not in the BC position. Abduction significantly lengthened the coracoid base, which was shortest in the BC position with ER (24 +/- 4 mm) and longest in the lateral decubitus 2 position with IR (33 +/- 5 mm). The coracoid base, where sutures are placed during plication of the interval, was observed to lengthen and, therefore, loosen with IR and abduction. To prevent postoperative ER restriction, plication should be made in ER or neutral rotation when operating in the BC position and the degree of abduction should be decreased and the shoulder held in ER when operating in the lateral decubitus position.