Pectoralis-major-Transfer bei chronischer Subskapularisinsuffizienz

OBJECTIVE: Pain-free movement and stability of the shoulder joint after restoration of muscular balance between the internal and external rotators. Eradication of anterior impingement. INDICATIONS: Irreparable rupture of the subscapularis tendon in active patients. CONTRAINDICATIONS: Less active patients who are older than about 60 years. Concomitant infraspinatus tendon rupture. Frozen shoulder. Rotator cuff arthropathy. SURGICAL TECHNIQUE: General anesthetic and beach-chair position with the arm freely mobile. Deltopectoral approach. Exposure of the lesser tubercle and the conjoined tendon of coracobrachialis and the short head of the biceps. Half to two thirds of the insertion of pectoralis major at the humeral shaft are detached proximally, held in a suture loop, and passed under the conjoined tendon. The tendon is then fixed transosseously to the lesser tubercle, and range of motion is evaluated. External rotation of up to 30 degrees without tension must be confirmed. POSTOPERATIVE MANAGEMENT: A shoulder strap is worn for 6 weeks and passive physiotherapy is commenced on day 2 postoperatively. External rotation can only be practiced after week 7. RESULTS: 23 patients were available to follow-up. There were 13 cases of anterosuperior defect with irreparable supraspinatus tendon. The preoperative Constant Score of 35 points improved to a postoperative score of 68 points. It was not possible to restore powerful internal rotation. Preoperative impingement syndrome was eradicated.     

Boytchev procedure for the treatment of anterior shoulder instability

Most of the operative techniques described for the treatment of recurrent anterior dislocations or subluxations of the shoulder have two distinct disadvantages: the need to immobilize the arm for several weeks and loss of external rotation. These disadvantages provided an incentive for conducting a clinical evaluation of an operation originally described by Boytchev and modified by the author. In this procedure, the conjoined tendons of the coracobrachialis and the short head of the biceps with the detached tip of the coracoid process are rerouted posterior to the subscapularis muscle and reattached to the coracoid process, providing a dynamic muscular sling immediately anteroinferior to the glenohumeral joint, especially when the arm is in a vulnerable position of abduction and external rotation. A total of 26 repairs with a minimal follow-up period of two years were reviewed. There were 22 men and four women with an average age of 22 years. The results were satisfactory in all patients. Loss of external rotation of less than 15 degrees was noted in eight patients. There were no redislocations. This procedure provides immediate stability to the shoulder allowing range of motion exercises to begin from the first postoperative day.     

The Boytchev procedure for recurrent anterior dislocation of the shoulder. A controversial technique

In the Boytchev technique the conjoined tendons of the coracobrachialis and short head of the biceps, together with the tendon of the pectoralis minor and the detached tip of the coracoid process are rerouted behind the subscapularis muscle, and reattached to the coracoid process with a screw. During a 10-year period 37 patients with recurrent anterior dislocation underwent a Boytchev procedure. Twenty-six patients (with 27 shoulders) were available to follow-up. The results of this retrospective study were disappointing, as the overall redislocation rate was 44%. The opinions of other authors were found to be extremely divergent.     

Quantitative determination of articular pressure in the human shoulder joint

The objective of this study was to determine experimentally the effect of individual variations in articular surface geometry on the shoulder joint pressure distribution in functionally important arm positions. The location and size of the load-bearing areas and maximal pressures of 10 cadaver shoulder joints were examined at 30 degrees, 90 degrees, and 150 degrees of abduction (+/-90 degrees external rotation) and 120 degrees flexion with pressure-sensitive film. Only parts of the glenoid cavity were involved in the load transfer, some specimens showing central and other bicentric (superior-inferior) pressure maxima during abduction and flexion. The load-bearing areas were more central at external rotation, suggesting that the humeral head is not a perfect sphere. The maximal pressure was recorded at 90 degrees of abduction with 90 degrees external rotation, with 5.1 MPa for the elevation for single- and >10 MPa for double-arm weight. The study demonstrates that shoulder joint pressure cannot be calculated analytically but depends on subtle variations of joint incongruity.     

如何使用术中超声探测肱骨近端板钉固定后的螺钉穿透:一项初步尸体研究

目的 探讨肱骨近端骨折板钉固定术中使用超声判断螺钉是否穿透肱骨头关节面.方法 采用尸体肩关节作为研究对象,将肱骨近端解剖锁定板固定于肱骨近端后,制作肱骨头9枚钉孔穿透模型,并用超声探查肱骨头关节面穿透情况,记录观察中的肩关节活动范围及超声探头在肩关节表面的位置.结果 右侧肩关节1～9号钉孔探及穿透时的肩关节活动度分别为...     

The effect of the long head of the biceps on glenohumeral kinematics

The long head of the biceps has been described as a stabilizing force in the setting of glenohumeral instability. However, data are lacking on the effect of loading the long head of the biceps on glenohumeral kinematics. Six cadaveric shoulders were tested for glenohumeral rotational range of motion and translation using a custom shoulder testing system and the Microscribe 3DLX (Immersion, San Jose, CA). The path of glenohumeral articulation (PGA) was measured by calculating the humeral head center with respect to the glenoid articular surface at maximal internal rotation, 30 degrees, 60 degrees, 90 degrees, and maximal external rotation. Significant decreases in glenohumeral rotational range of motion and translation were found with 22-N biceps loading vs the unloaded group. With respect to the PGA, the humeral rotation center was shifted posterior with biceps loading at maximal internal rotation, 30 degrees, and 60 degrees of external rotation. Loading the long head of the biceps significantly affects glenohumeral rotational range of motion, translations, and kinematics.     

Retroversion of the humeral head in the normal shoulder and its relationship to the normal range of motion

Retroversion of the humeral head and the range of motion of the shoulder joint in both the frontal and the scapular plane have been studied in 100 shoulder joints in 50 healthy subjects, 25 men and 25 women. The average angle for humeral head retroversion was 33 degrees on the dominant side and 29 degrees for the nondominant side. There was no difference between genders. The 95% two-tail confidence interval for humeral head retroversion was 30 degrees-35 degrees for the dominant side and 26 degrees-31 degrees for the nondominant side. A larger retroversion angle was consistent with an increased range of external rotation. Mean external rotation in 90 degrees abduction was 105 degrees in the frontal plane and 120 degrees in the scapular plane. External rotation in 90 degrees abduction was greater in women than in men, but there was no difference between dominant and nondominant shoulder joints. The range of motion of rotation was found to be greater than the accepted normal values.     

Influence of humeral prosthesis height on biomechanics of glenohumeral abduction. An in vitro study

BACKGROUND: During shoulder replacement surgery, the normal height of the proximal part of the humerus relative to the tuberosities frequently is not restored because of differences in prosthetic geometry or problems with surgical technique. The purpose of the present study was to determine the effect of humeral prosthesis height on range of motion and on the moment arms of the rotator cuff muscles during glenohumeral abduction. METHODS: Tendon excursions and abduction angles were recorded simultaneously in six cadaveric specimens during passive glenohumeral abduction in the scapular plane. Moment arms were calculated for each muscle by computing the slope of the tendon excursion-versus-glenohumeral abduction angle relationship. The experiments were carried out with the intact joint and after replacement of the humeral head with a prosthesis that was inserted in an anatomically correct position as well as 5 and 10 mm too high. RESULTS: Insertion of the prosthesis in positions that were 5 and 10 mm too high resulted in significant and marked reductions of the maximum abduction angle of 10 degrees (range, 5 degrees to 18 degrees ) and 16 degrees (range, 12 degrees to 20 degrees ), respectively. In addition, the moment arms of the infraspinatus and subscapularis decreased by 4 to 10 mm. This corresponded to a 20% to 50% decrease of the abduction moment arms of the infraspinatus and an approximately 50% to 100% decrease of the abduction moment arms of the subscapularis, depending on the abduction angle and the part of the muscle being considered. CONCLUSIONS: If a humeral head prosthesis is placed too high relative to the tuberosities, shoulder function is impaired by two potential mechanisms: (1) the inferior capsule becomes tight at lower abduction angles and limits abduction, and (2) the center of rotation is displaced upward in relation to the line of action of the rotator cuff muscles, resulting in smaller moment arms and decreased abduction moments of the respective muscles. Clinical Relevance: In patients managed with shoulder replacement surgery, limitation of range of motion, loss of abduction strength, and overload with long-term failure of the supraspinatus tendon are potential consequences of positioning the humeral head of the prosthesis proximal to the anatomic position.     

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.

     

The effect of articular malposition after total shoulder arthroplasty on glenohumeral translations, range of motion, and subacromial impingement

The articular surface of the normal humeral head has a variable posterior and medial offset with respect to the central axis of the humeral shaft. Recreation of the normal humeral head shaft offset is postulated to be an important consideration during shoulder arthroplasty. However, the effect of humeral head malposition is unknown. The purpose of this study was to determine the effect of articular malposition after total shoulder arthroplasty on glenohumeral translation, range of motion, and subacromial impingement. Twenty-one human cadavers were dissected and tested with the use of an active or passive shoulder model. Range of motion and translation were recorded by means of an electromagnetic tracking device. The experiment was performed in 2 phases. For kinematics study, 11 cadaver shoulders were positioned both passively and actively from maximum internal rotation to maximum external rotation at 90 degrees of total elevation in the scapular plane. Three rotator cuff and 3 deltoid muscle lines of action were simulated for active joint positioning. Passive joint positioning was accomplished with the use of a torque wrench and a nominal centering force. The testing protocol was used for the natural joint as well as for 9 prosthetic head locations: centered and 2- and 4-mm offsets in the anterior, posterior, inferior, and superior directions. Repeated-measures analysis of variance was used to test for significant differences in the range of motion and translation between active and passive positioning of the natural joint as well as all prosthetic head positions. (2) For impingement study, 10 cadaver shoulders were used in a passive model, loading the tendons of the rotator cuff with a 30-N centering force. The humerus was passively rotated from maximum internal rotation (1500 Nmm) to maximum external rotation (1500 Nmm) by means of a continuous-recording digital torque wrench. Trials were performed with the use of centered, 4-, 6-, and 8-mm offset heads in the anterior, posterior, superior, and inferior positions before and after removal of the acromion and coracoacromial ligament. The relation between change in mean peak torque (with and without acromion), passive range of motion, and humeral head offset was analyzed by means of repeated-measures analysis of variance. In the kinematics study, total range of motion and all humeral translations were greater with passive joint positioning than with active positioning (P =.01) except for total superior-inferior translation and superior-inferior translation in external rotation. Anterior to posterior humeral head offset was associated with statistically significant changes in total range of motion (P =.02), range of internal rotation (P =.02), range of external rotation (P =.0001), and total anterior-posterior translation (P =.01). Superior to inferior humeral head offset resulted in statistically significant changes in total range of motion (P =.02), range of internal rotation (P =.0001), anterior-posterior translation during external rotation (P =.01), and total superior-inferior translation (P =.03). In the impingement study, there was a significant increase in torque from centered to 4-mm inferior offset (P =.006), 6-mm inferior offset (P <.001), and 8-mm inferior offset (P <.001). There was no significant increase in torque with superior, anterior, and posterior offsets. Glenohumeral motion significantly decreased from 129 degrees for centered head to 119 degrees for 8-mm superior (P =.002), 119 degrees for 8-mm anterior (P =.014), 118 degrees for 8-mm inferior (P <.001), and 114 degrees for 8-mm posterior (P =.001). Humeral articular malposition of 4 mm or less during prosthetic arthroplasty of the glenohumeral joint may lead to small alterations in humeral translations and range of motion. Inferior malposition of greater than 4 mm can lead to increased subacromial contact; offset of 8 mm in any direction results in significant decreases in passive range of motion. Therefore if subacromial contact is to be minimized and glenohumeral motion maximized after shoulder replacement, anatomic reconstruction of the humeral head-humeral shaft offset to within 4 mm is desirable.     

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%.     

A cadaveric model of the throwing shoulder: a possible etiology of superior labrum anterior-to-posterior lesions

BACKGROUND: It has been speculated that a shift of the throwing arc commonly develops in athletes who perform overhead activities, resulting in greater external rotation and decreased internal rotation caused by anterior capsular laxity and posterior capsular contracture, respectively. Osseous adaptation in the form of increased humeral and glenoid retroversion may provide a protective function in the asymptomatic athlete but cannot explain the pathological changes seen in the shoulder of the throwing athlete. Therefore, the objective of the present study was to examine the biomechanical effects of capsular changes in a cadaveric model. METHODS: Ten cadaveric shoulders were tested with a custom shoulder-testing device. Humeral rotational range of motion, the position of the humerus in maximum external rotation, and glenohumeral translations in the anterior, posterior, superior, and inferior directions were measured with the shoulder in 90 degrees of abduction. Translations were measured with the humerus secured in 90 degrees of external rotation. To simulate anterior laxity due to posterior capsular contracture, the capsule was nondestructively stretched 30% beyond maximum external rotation with the shoulder in 90 degrees of abduction. This was followed by the creation of a 10-mm posterior capsular contracture. Rotational, humeral shift, and translational tests were performed for the intact normal shoulder, after anterior capsular stretching, and after simulated posterior capsular contracture. RESULTS: Nondestructive capsular stretching resulted in a significant increase in external rotation (average increase, 18.2 degrees 2.1 degrees ; p < 0.001), and subsequent simulated posterior capsular contracture resulted in a significant decrease in internal rotation (average decrease, 8.8 degrees +/- 2.3 degrees ; p = 0.02). There also was a significant increase in anterior translation with the application of a 20-N anterior translational force after nondestructive capsular stretching (average increase, 1.7 +/- 0.3 mm, p = 0.0006). The humeral head translated posteroinferiorly when the humerus was rotated from neutral to maximum external rotation. This did not change significantly in association with anterior capsular stretching. Following simulated posterior capsular contracture, there was a trend toward a more posterosuperior position of the humeral head with the humerus in maximum external rotation in comparison with the position in the stretched conditions, although these differences were not significant. CONCLUSIONS: A posterior capsular contracture with decreased internal rotation does not allow the humerus to externally rotate into its normal posteroinferior position in the cocking phase of throwing. Instead, the humeral head is forced posterosuperiorly, which may explain the etiology of Type-II superior labrum anterior-to-posterior lesions in overhead athletes.     

Magnetic resonance imaging and clinical findings before and after tendon transfers about the shoulder in children with residual brachial plexus birth palsy

The purpose of this study was to assess the magnetic resonance imaging (MRI) and clinical outcome after tendon transfers about the shoulder in children with residual brachial plexus birth palsy. Twenty-three children with an average age at surgery of 5.3 +/- 1.7 years underwent transfer of the latissimus dorsi and teres major to the posterior rotator cuff with or without concomitant musculotendinous lengthenings. Preoperative MRI revealed glenoid retroversion measuring -25.3 +/- 14.3 degrees and only 29.5 +/- 15.5% percent of humeral head anterior to the middle of the glenoid. Clinical evaluation showed significant improvements in external rotation and abduction. Postoperative MRI 1 year after surgery revealed no change in glenoid retroversion (-24.5 +/- 14.2) or percent of humeral head anterior to the middle of the glenoid (28.4 +/- 14.9%). These results demonstrate that tendon transfers improve overall shoulder motion but do not reduce humeral head subluxation or enhance glenohumeral joint realignment.     

The coracoid impingement of the subscapularis tendon: a cadaver study

To study the anatomic relationships and varieties of anterior impingement of the rotator cuff, an examination of 124 shoulder joints from 62 embalmed cadavers was performed. The distance between the lesser tuberosity and the coracoid was measured at different degrees of humeral rotation in the shoulder joint. Neither lateral differences nor differences with respect to donor gender were found in the distance measurements between the coracoid process and the lesser tuberosity for any rotational angle. In addition, no significant differences were found between shoulders with and without rupture of the subscapularis tendon. No lateral dominance was found for the subscapularis tunnel area.     

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 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.     

Humeral head retroversion in competitive baseball players and its relationship to glenohumeral rotation range of motion

DESIGN: Prospective case series. OBJECTIVE: To determine if an osseous component in the form of increased humeral head retroversion may contribute to observed differences in the amount of rotation between the throwing and nonthrowing shoulders of competitive baseball players. BACKGROUND: Differences in side-to-side shoulder rotation range of motion (ROM) are seen in throwing athletes. In the past, these differences have been attributed to adaptive changes to the surrounding soft tissue structures, including attenuation of the anteroinferior capsule and ligaments, and tightening of the posterior capsule. Recent studies, however, suggest that a possible osseous adaptation in the form of increased humeral head retroversion may be the cause of this side-to-side ROM difference. bilateral computed tomography (CT) scans to determine the angle of humeral head version. Maximal shoulder internal and external rotation ROM at 90 degrees abduction were measured both passively and actively for both shoulders. RESULTS: Players had statistically significant (P<.001) side-to-side difference in humeral head version, with an average of 10.60 greater retroversion in their throwing arm compared to their nonthrowing arm. A significant side-to-side difference was not observed in the control group (average difference, 2.30; P = .197). Greater humeral head retroversion was associated with greater external rotation ROM and lesser internal rotation ROM in the throwing arm of the throwers. CONCLUSIONS: Our results indicated that highly competitive baseball players do have greater humeral head retroversion in their dominant arm, which can partially explain the observed differences in side-to-side shoulder rotation ROM.     

Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis

BACKGROUND: The results of shoulder arthroplasty for osteoarthritis have been reported to be excellent or good for the majority of patients, but the value of using a glenoid component and the anatomic factors that affect outcome are still debated. The purpose of this study was to evaluate the influence of an operatively confirmed full-thickness tear of the rotator cuff, the severity of preoperative erosion of glenoid bone, preoperative radiographic evidence of subluxation of the humeral head, and the severity of preoperative loss of the passive range of motion on the outcome of total shoulder arthroplasty and hemiarthroplasty. METHODS: In a multicenter clinical outcome study, we evaluated 128 shoulders in 118 patients with primary osteoarthritis who had been followed for a mean of forty-six months (range, twenty-four to eighty-seven months). RESULTS: Patients with <10 degrees of passive external rotation preoperatively had significantly less improvement in external rotation after hemiarthroplasty (p = 0.006). Thirteen (10%) of the 128 shoulders had a repairable full-thickness tear of the supraspinatus tendon, but these tears did not affect the overall American Shoulder and Elbow Surgeons score, the decrease in pain, or patient satisfaction. Severe or moderate eccentric glenoid erosion was seen in twenty-nine (23%) of the 128 shoulders, and total shoulder arthroplasty resulted in significantly better passive total elevation and active external rotation as well as a trend toward significantly better active forward flexion than did hemiarthroplasty in these shoulders. The humeral head was subluxated posteriorly in twenty-three shoulders (18%), and when they were compared with the other shoulders in the study, these shoulders were found to have lower final American Shoulder and Elbow Surgeons scores, more pain, and decreased active external rotation following either total shoulder arthroplasty or hemiarthroplasty. CONCLUSIONS: On the basis of our data, we recommend the use of a glenoid component in shoulders with glenoid erosion. Humeral head subluxation was associated with a less favorable result regardless of the type of shoulder arthroplasty and must be considered in preoperative planning and counseling. Severe loss of the passive range of motion preoperatively was associated with a decreased passive range of motion postoperatively. A repairable tear of the supraspinatus tendon is not a contraindication to the use of a glenoid component. .     

Modified Boytchev procedure for treatment of recurrent anterior dislocation of shoulder

Background:

More than 200 different operations have been described for the treatment of recurrent anterior dislocation of shoulder. The Modified Boytchev procedure employs rerouting of the detached tip of coracoid process with its attached conjoined tendon (short head of biceps and coracobrachialis) deep to subscapularis and reattaches to its anatomical location. We conducted a study on evaluation of long-term effect of modified Boytchev procedure and to compare our results with other studies published in literature.

Materials and Methods:

Since June 2002, modified Boytchev procedure was performed on 48 patients, who presented with recurrent anterior dislocation. 45 were men and 3 were women and were in the age group of 18-40 years (mean 27.83±4.95 years). Forty patients were affected on the dominant side and rest on the non-dominant side. The mean number of dislocations in these patients was 18.22±12.08. The mean followup period was 58.13±19.06 months (range 18-96 months). The patients were evaluated by visual analogue score, modified American Shoulder and Elbow Surgeon''s Score (ASES), and Single Assessment Numeric Evaluation (SANE) score at the last followup.

Results:

All the patients regained almost preoperative range of forward flexion at the last followup. In the preoperative period the mean external rotation deficit at 0° and at 90° of abduction was 13.22°±5.16° and 18.06°±6.50°, respectively. At the last followup, the mean external rotation deficit at 0° and at 90° of abduction was 8.06°±2.47° and 8.95°±2.07°, respectively. This improvement in external rotation deficit was statistically significant (P<.05). Preoperative scores were compared with the most recent followup scores for all variables with use of a paired t test. All patients had significant improvement in visual analogue score, modified American Shoulder and Elbow Surgeon''s Score (ASES), and Single Assessment Numeric Evaluation (SANE) score at the last followup. Four of the patients developed superficial infection which got resolved after treating with antibiotics, and two of the patients developed transient musculocutaneous nerve paresis. There was no radiological evidence of loosening and migration of coracoid screw or any glenohumeral arthritis on subsequent followup of skiagrams in any of our patients.

Conclusion:

Modified Boytchev procedure is an efficacious and technically simple procedure to treat recurrent anterior dislocation of shoulder.     

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