Effect of joint compression on inferior stability of the glenohumeral joint

To determine the relative importance of negative intraarticular pressure, capsular tension, and joint compression on inferior stability of the glenohumeral joint we studied 17 fresh, normal adult cadaver shoulders using a "3 degrees of freedom" shoulder test apparatus. Translations were measured in intact and vented shoulders while a 50-N superior and inferior directed force was applied to the shoulder. Three different joint compressive loads (22 N, 111 N, 222 N) were applied externally. Tests were performed in 3 positions of humeral abduction in the scapular plane (0 degree, 45 degrees, 90 degrees) and in 3 positions of rotation (neutral, maximal internal, and maximal external). After tests of the intact and vented shoulder, the glenohumeral ligaments were sectioned and tests were repeated. With minimal joint compression of 22 N, negative intraarticular pressure and capsular tension limited translation of the humeral head on the glenoid. Increasing the joint compressive load to 111 N resulted in a reduction of mean inferior translation from 11.0 mm to 2.0 mm at 0 degree abduction, from 21.5 mm to 1.4 mm at 45 degrees abduction, and from 4.5 mm to 1.2 mm at 90 degrees abduction. With a compressive load of 111 N, venting the capsule or sectioning of glenohumeral ligaments had no effect on inferior stability. Clinical relevance: Glenohumeral joint compression through muscle contraction provides stability against inferior translation of the humeral head, and this effect is more important than negative intraarticular pressure or ligament tension.     

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.     

Determination of in vivo glenohumeral translation using fluoroscopy and shape-matching techniques

The purpose of this study was to investigate glenohumeral translation in-vivo during active shoulder abduction in the scapular plane. Three-dimensional (3D) models of 9 shoulders were created from CT scans. Fluoroscopic views aligned to the plane of the scapula were recorded during active arm abduction with neutral rotation. 3D motions were determined using model-based 3D-to-two-dimensional (2D) registration. Humeral translation was referenced to the glenoid center in the superior/inferior direction. The humerus moved an average of 1.7 mm superior with arm abduction, from an inferior location to the glenoid center. The humeral head was centered within 1 mm from the glenoid center above 80 degrees abduction. Variability in glenohumeral translation between shoulders decreased significantly from initial to final arm abduction. Our findings agree with some authors' observations of inferior-to-central translation of the humerus and behavior as a congruent ball and socket. We believe this information will help improve the understanding of shoulder function.     

Anterior-inferior capsular shift of the shoulder: a biomechanical comparison of glenoid-based versus humeral-based shift strategies

This study compared the biomechanical effects of an anterior-inferior capsular shift based at the humeral side with one on the glenoid side of the joint on resultant multidirectional glenohumeral translation and rotation. Nine matched pairs of fresh cadaveric shoulders were placed in a testing apparatus that constrained 3 rotations but allowed simultaneous free translation of the humeral head with respect to the glenoid. The right and left shoulders of each of the matched pairs were randomized to undergo either a glenoid-based or humeral-based anterior capsular shift. The shoulders were tested vented and following the capsular shift procedure. Translational testing was performed at 0 degrees, 45 degrees, and 90 degrees of glenohumeral elevation with the humerus in neutral rotation, 30 degrees internal rotation, and 30 degrees external rotation. Sequential loads of 30 N in anterior, posterior, and inferior directions were applied while maintaining a 22-N joint compressive load. The maximum arc of internal and external rotation after application of a 1-newton-meter moment was determined for the vented specimens and then after the capsular shift procedure. Both shift strategies resulted in significant limitation of anterior, posterior, and inferior translation in all of the tested positions. No significant differences were noted between the 2 shift strategies with respect to restriction of translation in the anterior or inferior directions. The glenoid-based shift caused a significantly greater decrease in posterior translation at 45 degrees and 90 degrees of abduction. With respect to rotation, the glenoid-based shift exerted significantly greater restriction on external rotation than the humeral-based shift. This study supports the use of either a humeral-based or glenoid-based shift to control multidirectional glenohumeral instability. Greater reduction in external rotation was demonstrated after the glenoid-based shift. Specific differences demonstrated in translation control for humeral-based versus glenoid-based capsular shift procedures may be useful in tailoring a procedure for specific instability patterns.     

Effect of selective capsulorrhaphy on the passive range of motion of the glenohumeral joint

BACKGROUND: Capsulorrhaphy of the glenohumeral joint is a common surgical procedure for the treatment of instability caused by increased capsular laxity. The effect of capsulorrhaphy on the range of motion of the shoulder is poorly understood. METHODS: We simulated localized capsular contractures by selective capsular plications in eight human cadaveric shoulders and studied the effect of such plications on the passive range of glenohumeral abduction, flexion, and external and internal rotation in different degrees of abduction. A 0.5 or 1-N-m torque was applied to the humerus, and the range of glenohumeral motion was measured with electronic goniometers in three planes and compared with those of the intact shoulder. RESULTS: Anterosuperior capsular plication most markedly affected external rotation of the adducted arm, decreasing it by a mean of 30.1 degrees (p < 0.0001). Anteroinferior plication significantly reduced abduction by a mean of 19.4 degrees (p < 0.0001) and external rotation by a mean of 20.6 degrees (p = 0.0046). Posterosuperior plication mostly limited internal rotation of the adducted arm (mean decrease, 16.1 degrees, p = 0.0045). On the average, total anterior and total posterior plication each limited flexion by approximately 20 degrees (p = 0.005) and abduction by >or=15 degrees (p < 0.005), whereas total anterior plication limited external rotation by >30 degrees (p 20 degrees (p < 0.0001). Total inferior capsular plication restricted abduction (by a mean of 27.7 degrees, p = 0.0001), flexion, and rotation. Total superior plication restricted external rotation and flexion. CONCLUSIONS AND CLINICAL RELEVANCE: Localized plications of the glenohumeral joint capsule lead to predictable patterns of loss of glenohumeral mobility. If plication is planned, losses of movement can be anticipated. The findings of this study may assist surgeons in identifying the parts of the capsule that are contracted and that may need lengthening.     

Internal impingement of the shoulder: a clinical and arthroscopic analysis.

Internal impingement was first described by Walch in 1992 and defined as contact between the supraspinatus tendon and posterior-superior glenoid rim with the shoulder in the cocked, throwing position of 90 degrees of abduction and maximum external rotation. The hypothesis of the study was that this contact may be seen in patients who are not throwing athletes nor in those who have instability. One hundred five consecutive patients who underwent shoulder arthroscopy were prospectively studied with preoperative history and physical examination. All patients underwent general anesthesia and arthroscopy with a standard posterior portal. With the patient under arthroscopy the arm was placed in abduction and external rotation until contact was made or until full elevation was reached. Eighty-five percent (N = 90) of the patients made contact between the rotator cuff and glenoid rim at an average of 95 degrees of abduction and 74 degrees of external rotation. No statistically significant relationship was seen (P > .05) between the position of contact at internal impingement and mechanism of injury, throwing versus nonthrowing, instability, rotator cuff tear, preoperative external rotation, or preoperative impingement signs. The intraoperative finding of contact of the rotator cuff to the posterosuperior glenoid with the arm in abduction and external rotation can occur in a wide spectrum of shoulder disease and is not limited to the throwing athlete. Not all patients with increased laxity and instability demonstrate this contact, suggesting that these factors may not be essential for internal impingement.     

MRI-based 3-D analysis of the glenohumeral translation in patients with shoulder instability

AIM: Until now, pathological translation of the glenohumeral joint could not be assessed three-dimensionally and in functionally important arm positions in the living. The objektive of this study was therefore to develop an MR-based technique for determining the three-dimensional glenohumeral translation in functionally relevant positions in vivo. METHOD: In an open MR scanner both shoulder joints of 5 volunteers with an unilateral traumatic instability were examined in different positions of abduction and rotation. After semiautomatic segmentation, 3D reconstruction of the bony structures of the shoulder girdle was performed and the center of mass of the glenoid cavity was determined and used as reference point. In a virtual reality, the midpoint of the humeral head was assessed and its position relative to the center of mass of the glenoid cavity was calculated. RESULTS: At 30 degrees of abduction, in both shoulders, the humeral head was positioned inferior and posterior relative to the glenoid cavity (healthy: 0.42 +/- 1.1 inf., 0.75 +/- 1.0 mm post.; unstable: 1.31 +/- 0.87 mm inf., 0.51 +/- 1.28 mm post.) The maximal translation (to anterior and inferior) was observed both on the healthy side (mean 1.0 mm, max. 1.8 mm) and in the unstable shoulders (mean 2.5 mm, max. 4.6 mm) with the arm in 90 degrees of abduction and external rotation, thus being 1.7 to 2.5 times higher in the pathological shoulders. CONCLUSIONS: With this technique the glenohumeral translation can be quantified three-dimensionally in functionally important positions and without projectional artefacts. In the future, this method can be applied to patients with different entities of shoulder instability.     

Surgical anatomy of the posterior shoulder: effects of arm position and anterior-inferior capsular shift.

The purposes of this study were to evaluate anatomically various surgical intervals to the posterior shoulder and to determine the effects of varying arm positions and anterior-inferior capsular shift (AICS) on the relation of the posterior neurovascular structures to fixed bony landmarks. Fourteen cadaveric shoulders were dissected. The posterior surgical anatomy was defined, and the distances from fixed bony landmarks to neurovascular and musculotendinous structures were determined with digital calipers. Measurements were made with the arm in various positions and repeated after AICS. The most direct anatomic approach to the posterior shoulder was through a deltoid split in the raphe from the posterolateral corner of the acromion (PLCA), followed by an infraspinatus (IS) splitting incision. The IS/teres minor interval was at the inferior aspect of the glenoid rim and was difficult to locate in all specimens. The distance to the axillary nerve from the PLCA averaged 65 mm and decreased by an average of 14 mm (22%) with abduction and by 19 mm (29%) with extension. The posterior humeral circumflex artery was located along the humeral neck and was vulnerable to injury during lateral capsular dissection. The suprascapular nerve had multiple branches to the IS with most penetrating the muscle at its inferior portion. The closest branch to the glenoid rim was an average of 20 mm medial from it. No branch entered at the level of the IS raphe. The anatomic relations of the suprascapular nerve were unchanged after AICS. On the basis of this study, surgical exposure of the posterior shoulder with a deltoid split from the PLCA, followed by an IS split, appears to be anatomically safe. The arm position should be in neutral rotation, especially if previous anterior capsular procedures have been performed, which can alter the posterior neurovascular anatomic relations.     

In vivo articular cartilage contact at the glenohumeral joint: preliminary report

BACKGROUND: Little is known about normal in vivo mechanics of the glenohumeral joint. Such an understanding would have significant implications for treating disease conditions that disrupt shoulder function. The objective of this study was to determine articular contact locations between the glenoid and humeral articular surfaces in normal subjects during shoulder abduction with neutral, internal, and external rotations. We hypothesized that glenohumeral articular contact is not perfectly centered and is variable in normal subjects tested under physiological loading conditions. METHODS: Orthogonal fluoroscopic images and magnetic resonance image-based computer models were used to characterize the centroids of articular cartilage contact of the glenohumeral joint at various static, actively stabilized abduction and rotation positions in five healthy shoulders. The shoulder was investigated at 0 degrees , 45 degrees , and 90 degrees abduction with neutral rotation and then at 90 degrees abduction combined with active maximal external rotation and active maximal internal rotation. RESULTS: For all the investigated positions, the centroid of contact on the glenoid surface for each individual, on average, was more than 5 mm away from the geometric center of the glenoid articular surface. Intersubject variation of the centroid of articular contact on the glenoid surface was observed with each investigated position, and 90 degrees abduction with maximal internal rotation showed the least variability. On the humeral head surface, the centroids of contact were located at the superomedial quarter for all investigated positions, except in two subjects' positions at 0 degrees abduction, neutral rotation. CONCLUSIONS: The data showed that the in vivo glenohumeral contact locations were variable among subjects, but in all individuals they were not at the center of the glenoid and humeral head surfaces. This confirms that "ball-in-socket" kinematics do not govern normal shoulder function. These insights into glenohumeral articular contact may be relevant to an appreciation of the consequences of pathology such as rotator cuff disease and instability.     

Die arthroskopische Bankart-Operation mit Hilfe von resorbierbaren Nahtankern

OBJECTIVE: Arthroscopic refixation of the labrum-ligament complex at the glenoid. INDICATIONS: Posttraumatic anterior or anterior-inferior shoulder instability with Bankart or ALPSA lesion (anterior labral periosteal sleeve avulsion). CONTRAINDICATIONS: Atraumatic shoulder instability. Instabilities due to blunted or frayed degeneration of the labrum-ligament complex. HAGL lesion (humeral avulsion of the glenohumeral ligaments) with humeral detachment of the glenohumeral ligaments. Larger bony glenoid defects. SURGICAL TECHNIQUE: Mobilization of the labrum-ligament complex from the neck of the glenoid, superior tightening and refixation at the glenoid rim with the aid of absorbable suture anchors. POSTOPERATIVE MANAGEMENT: Immobilization of the affected arm for 4 weeks in an immobilization bandage with abduction pillows. Daily pendulum exercises. Active flexion up to 70 degrees and abduction up to 40 degrees, all in neutral or internal rotation. Avoidance of external rotation for a total of 6 weeks. RESULTS: From January 1999 to December 2001, 58 patients with a Bankart or ALPSA lesion were treated with arthroscopic shoulder stabilization using absorbable suture anchors and slowly absorbable braided sutures. 56 patients underwent a follow-up clinical examination after, on average, 31 months (24-48 months). None of these patients had suffered more than five shoulder dislocations before the operation (average 2.8). Of the intraoperative lesions, a plain Bankart lesion was present in twelve patients (21.4%), 44 patients had an ALPSA lesion (78.6%), of which one in two were combined with an SLAP 2 or SLAP 3 lesion (superior labrum from anterior to posterior). In the evaluation using the Rowe Score, there was an excellent result for 40 patients (71.4%), and a good result for twelve (21.4%). Four patients suffered a repeat dislocation and were therefore classified as poor results (7.2%).     

Should acute anterior dislocations of the shoulder be immobilized in external rotation? A cadaveric study

The high recurrence rate associated with anterior shoulder dislocations may reflect inadequate healing of a Bankart lesion when the arm is immobilized in internal rotation. The effect of external rotation (ER) of the humerus on the glenoid-labrum contact of Bankart lesions was examined in 10 human cadaveric shoulders. The contact force between the glenoid labrum and the glenoid was measured in 60 degrees of internal rotation, neutral rotation, and 45 degrees of ER in 10 human cadaveric shoulders. No detectable contact force was found with the arm in internal rotation. The contact force increased as the arm passed through neutral rotation and reached a maximum at 45 degrees of ER. The contact force returned to 0 g when the arm was returned to neutral rotation. The mean contact force at 45 degrees of ER was 83.5 g. External rotation significantly increases the labrum-glenoid contact force and may influence the healing of a Bankart lesion.     

Arthroscopic release of the glenohumeral joint in shoulder stiffness: a review of 26 cases. French Society for Arthroscopy.

The purpose of this multicenter retrospective study of arthroscopic release of the glenohumeral joint was to evaluate the technical feasibility, the results, and the potential correlations between results and cause of the stiffness. Twenty-six shoulders in 25 patients (19 women and six men) were re-evaluated 3 to 72 months (mean, 21 months) after arthroscopic release of the glenohumeral joint. Diagnoses were primary frozen shoulder in 13 cases, bipolar stiffness (rotator cuff tear plus capsular contraction) in 3 cases, and postinjury or postsurgery stiffness in 10 cases. Results were evaluated on passive range of motion, Constant's score, and subjective assessment. Anterior or anterior inferior capsular release was done at the anterior rim of the glenoid fossa. Posterior capsule release was not performed in this series. There were no intraoperative complications. Mean range of motion gains were 86 degrees for forward elevation, 72 degrees for abduction, 34 degrees for external rotation, and 6 spinal processes for internal rotation. Constant's range of motion score increased from 12.9 out of 40 to 32 out of 40 points. Thirteen patients were very satisfied, 5 satisfied, 5 improved, and 3 unchanged. Range of motion gains were independent from the cause of shoulder stiffness, but global results were better in the primary frozen shoulder group in terms of pain and strength. Arthroscopic release of the glenohumeral joint is feasible and safe. For primary frozen shoulders, in case of failure of the functional treatment, arthroscopic release is a less traumatic alternative to manipulation under general anesthesia. For bipolar stiffness, arthroscopy provides the opportunity for treating concomitant lesions. For postsurgical stiffness, arthroscopic release improves range of motion, but the shoulder often remains painful.     

Biomechanical relevance of glenoid component positioning in the reverse Delta III total shoulder prosthesis

The presence of a notch at the inferior part of the scapular neck is a common radiographic finding in patients treated with a reverse Delta III shoulder prosthesis. It is thought that this notch is a result of mechanical contact between the polyethylene cup of the humeral implant and the inferior glenoid pole during adduction of the arm. This in vitro study assessed the effect of glenoid component positioning on glenohumeral range of motion in 8 shoulder specimens. Four different positions of the glenosphere were tested: glenosphere centered on the glenoid, leaving the inferior glenoid rim uncovered (configuration A); glenosphere flush with the inferior glenoid rim (configuration B); glenosphere extending beyond the inferior glenoid rim (configuration C); and glenosphere tilted downward 15 degrees (configuration D). The respective mean adduction and abduction angles in the scapular plane were -25 degrees and 67 degrees for configuration A, -14 degrees and 68 degrees for configuration B, -1 degrees and 81 degrees for configuration C, and -9 degrees and 75 degrees for configuration D. Placing the glenosphere distally (test configuration C) significantly improved adduction and abduction angles compared with all other test configurations (P < .001).     

Revision anterior capsular shoulder stabilization using hamstring tendon autograft and tibialis tendon allograft reinforcement: minimum two-year follow-up

Surgical treatment of anterior shoulder capsular deficiency has been a challenge for orthopaedic surgeons dealing with failed anterior shoulder stabilization procedures. We have used hamstring tendon autograft or tibialis tendon allograft to reinforce deficient anterior capsular tissue in patients with failed anterior shoulder stabilization. We performed a clinical follow-up of 15 patients at a minimum of 2 years after surgery, using the American Shoulder and Elbow Surgeons questionnaire, a physical examination, and radiographs. Thirteen patients were satisfied with their surgery. The mean American Shoulder and Elbow Surgeons score was 73, (range, 7-100). There were no postoperative dislocations. The operative shoulder had decreased range of motion compared with the contralateral shoulder. The operative arm lacked 10 degrees of forward flexion, 21 degrees of external rotation at the side, 24 degrees of external rotation with the arm in abduction, and 4 spinal levels of internal rotation. Two patients required total shoulder arthroplasty for painful glenohumeral arthritis. Clinical failure was related to glenohumeral arthritis or residual anterior shoulder apprehension. Our results support the use of hamstring autograft or tibialis anterior allograft for the reconstruction of the anterior capsule during revision shoulder stabilization surgery.     

Archer's shoulder. Recurrent posterior subluxation and dislocation of the shoulder in two archers

Two right-handed archers presented with posterior instability of the shoulder. A 19-year-old Japanese and a 26-year-old white male archer developed pain and instability of the shoulder of 6 months' duration. Both had engaged in archery for several years. Both exhibited a positive apprehension test and recurrent posterior subluxation and dislocation by flexing the arm to 80 degrees with internal rotation. Both could reduce the instability with a snap by extending the arm. For the subluxation, Neer's inferior capsular shift procedure via a posterior approach was performed. For the dislocation, a posterior bone block was added to the inferior capsular shift. The posterior capsular redundancy was marked in both cases. At 5 and 9-years follow up respectively, both were doing archery and full activities without pain. These cases are thought to be examples of how a repetitive force can cause shoulder instability.     

Deficits following nonoperative treatment of displaced midshaft clavicular fractures

BACKGROUND: Displaced fractures of the midpart of the clavicular shaft are generally treated nonoperatively, and few functional deficits have been reported. Whereas prior investigators have presented radiographic and surgeon-based outcomes, we used a patient-based outcome questionnaire and objective muscle-strength testing to evaluate a series of patients who had received nonoperative care for a displaced midshaft fracture of the clavicle. METHODS: We identified thirty patients (twenty-two men and eight women with a mean age of thirty-seven years) who had sustained a displaced midshaft fracture of the clavicle. All patients were treated nonoperatively. At a mean of fifty-five months, and a minimum of twelve months, outcomes were measured with the Constant shoulder score and the DASH (Disabilities of the Arm, Shoulder and Hand) patient questionnaire. In addition, objective shoulder muscle-strength testing was performed with the Baltimore Therapeutic Equipment Work Simulator, with the uninjured arm serving as a control. RESULTS: The range of motion was well maintained, with flexion averaging 170 degrees +/- 20 degrees and abduction averaging 165 degrees +/- 25 degrees . Compared with the strength of the uninjured shoulder, the strength of the injured shoulder was reduced to 81% for maximum flexion, 75% for endurance of flexion, 82% for maximum abduction, 67% for endurance of abduction, 81% for maximum external rotation, 82% for endurance of external rotation, 85% for maximum internal rotation, and 78% for endurance of internal rotation (p < 0.05 for all values). The mean Constant score was 71 points, and the mean DASH score was 24.6 points, indicating substantial residual disability. CONCLUSIONS: Traditionally, good results with minimal functional deficits have been reported following nonoperative treatment of clavicular fractures. However, surgeon-based methods of evaluation may be insensitive to loss of muscle strength. We detected residual deficits in shoulder strength and endurance in this patient population, which may be related to the significant level of dysfunction detected by the patient-based outcome measures.     

Position of immobilization after dislocation of the shoulder. A cadaveric study

BACKGROUND: After reduction of a shoulder dislocation, the torn edges of a Bankart lesion need to be approximated for healing during immobilization. The position of immobilization has traditionally been adduction and internal rotation, but there is little direct evidence to support or discredit the use of this position. The purpose of the present study was to determine the relationship between the position of the arm and the coaptation of the edges of a simulated Bankart lesion created in cadaveric shoulders. METHODS: Ten thawed fresh-frozen cadaveric shoulders were used for experimentation. All of the muscles were removed to expose the joint capsule. A simulated Bankart lesion was created by sectioning the anteroinferior aspect of the capsule from the labrum. With linear transducers attached to the anteroinferior and inferior portions of the Bankart lesion, the opening and closing of the lesion were recorded with the arm in 0, 30, 45, and 60 degrees of elevation in the coronal and sagittal planes as well as with the arm in rotation from full internal to full external rotation in 10-degree increments. RESULTS: With the arm in adduction, the edges of the simulated Bankart lesion were coapted in the range from full internal rotation to 30 degrees of external rotation. With the arm in 30 degrees of flexion or abduction, the edges of the lesion were coapted in neutral and internal rotation but were separated in external rotation. At 45 and 60 degrees of flexion or abduction, the edges were separated regardless of rotation. CONCLUSIONS: The present study demonstrated that, in the cadaveric shoulder, there was a so-called coaptation zone in which the edges of a simulated Bankart lesion were kept approximated without the surrounding muscles.     

The effect of open Bristow-Latarjet procedure for anterior shoulder instability: a 10-year study

Operative procedures are the usual treatment for patients with anterior traumatic shoulder instabilities. Soft tissue procedures, Bankart repair, cannot be performed in some patients. They need Bristow-Latarjet one. We decided to determine midterm results of this procedure in almost all types of anterior shoulder instability, even shoulders with Bankart lesion in non-athletic cases. Thirty patients after Bristow-Latarjet procedure from 1997 to 2007 were followed 2–8 years. Clinical outcomes, consisted of muscle strength, range of motion (mean 8.66 degrees decreased in external rotation with arm in neutral position and 18.33 with arm in 90 degrees of abduction), recurrent instability (no relapse), and Rowe score (mean 77.66) showed good to excellent results. We had no screw-related or neurovascular complications. Thirty percent of cases had signs of mild arthropathy. Although Bankart procedure is the preferred method in patients with isolated Bankart lesion, but we can perform Bristow-Latarjet for all types of anterior traumatic shoulder instability in non-athletics cases with acceptable results.     

Quantitation of in situ contact areas at the glenohumeral joint: a biomechanical study.

Glenohumeral arthritis may result from abnormal articular mechanics, and shoulder reconstructive procedures often rely implicitly on the belief that the restoration of normal articular mechanics is required to obtain satisfactory clinical results. Despite this, limited knowledge of normal or pathologic glenohumeral joint articular mechanics and contact is available. This study uses a stereophotogrammetry technique to determine contact areas in normal cadaver glenohumeral joints with intact ligaments and capsule through a large range of motion using simulated forces of the four rotator cuff muscles and three deltoid heads. All shoulders were first elevated to their maximum elevation in the scapular plane at an external rotation (starting rotation = 40 +/- 8 degrees), which allowed each shoulder to attain its maximal elevation in the scapular plane, and then repeated at 20 degrees internal to this rotation. Contact areas consistently increased with increasing elevation until 120 degrees to an average of 5.07 cm2 before decreasing with further increased elevation to an average of 2.59 cm2 at 180 degrees of total arm elevation. At 20 degrees internal to the starting rotation, contact areas reached high values 60 degrees earlier (averaged 4.56 cm2 at 60 degrees of total arm elevation) and then remained fairly constant through 120 degrees before decreasing with further increased elevation to 2.51 cm2 at 180 degrees total arm elevation. With increasing elevation in the external starting rotation, humeral head contact dramatically migrates from an inferior region to a superocentral-posterior region while glenoid contact shifts posteriorly. When the humeral shaft is positioned 20 degrees internal to the starting rotation, humeral head contact shifts from inferocentral-anterior to superocentral-posterior regions. Simultaneously, a similar posterior shift in glenoid contact is observed. Furthermore, whereas only a small portion of the humeral head surface area is in contact in any given position, contact on the glenoid surface is much more uniformly distributed over its entire articulating surface.     

Anterior and anterior-inferior shoulder instability: Treatment by glenoid labrum reconstruction and a modified capsular shift procedure

An anterior glenoid labrum reconstruction in conjunction with a modified anterior-inferior capsular shift is described and was performed in 64 patients (69 shoulders) with traumatic anterior or anterior-inferior glenohumeral instability. Sixty-three operations were performed for recurrent dislocation and six for recurrent subluxation. The patients in this study were extremely active in sports, with the majority of Tegner ratings exceeding 7.0. Fifty-six patients with 61 operated shoulders were available for clinical follow-up at an average of 36 months (range 28 to 78 months). With rating scales from the American Shoulder and Elbow Surgeons, pain improved from an average of 3.1 to an average of 4.4, stability improved from 1.1 to 4.5, and function improved from 2.5 to 3.8. Postoperative average ranges of motion were 180° of forward elevation, 72° of external rotation with the arm at the side, 92° of external rotation with the arm at 90° of abduction, and 90° of internal rotation with the arm at 90° of abduction. Ninety-five percent of the patients were satisfied with the procedure. Five patients suffered a recurrent dislocation, four from significant trauma. One additional patient experienced an episode of subluxation early in the recovery period. According to the criteria of Rowe, 90% had excellent or good results.