Electromyography in voluntary posterior instability of the shoulder

Electromyographic (EMG) activity of selected shoulder girdle muscles was analyzed during voluntary posterior subluxation of the glenohumeral joint in four subjects. Although there was a great deal of variation in the muscle activation patterns during subluxation, subjects either pushed the humeral head backwards with the anterior muscles (deltoid, biceps) or pulled the humeral head backwards with the infraspinatus and/or posterior deltoid. In all cases, inhibition of the scapular rotators and winging of the scapula accompanied this maneuver. The method used in this study is presented as an objective technique for quantifying EMG activity during subluxation and relocation phases of shoulder instability.     

Arthroscopic treatment of posterior shoulder instability: results in 33 patients

BACKGROUND: Posterior shoulder instability is a relatively rare condition and a surgical challenge. Arthroscopic techniques have allowed for a potential improvement as well as diagnosis and management of this condition. PURPOSE: To evaluate the outcomes of arthroscopic posterior shoulder stabilization and to evaluate preoperative and intraoperative variables as predictors of success. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Thirty-three consecutive patients with a mean age of 25 years (range, 19-34 years) who underwent posterior arthroscopic shoulder stabilization with suture anchors (mean, 3 anchors) or suture capsulolabral plication (mean, 5.3 stitches) or both were reviewed at a mean follow-up of 39.1 months (range, 22-60 months). Shoulder outcomes rating scores were determined using the American Shoulder and Elbow Surgeons Rating Scale, the Western Ontario Shoulder Instability Index, the Subjective Patient Shoulder Evaluation, and the Single Assessment Numeric Evaluation. RESULTS: There were 7 failures: 4 for recurrent instability and 3 for symptoms of pain. Overall, outcomes scores demonstrated mean values of the American Shoulder and Elbow Surgeons Rating Scale of 94.6, Subjective Patient Shoulder Evaluation of 20.0, Western Ontario Shoulder Instability Index of 389.4 (81.5% of normal), and Single Assessment Numeric Evaluation of 87.5. Patients with voluntary instability demonstrated worse outcomes (P = .025), and those with prior surgery of the shoulder also did worse (P = .02). CONCLUSION: Arthroscopic treatment of posterior shoulder instability is an effective means to improve symptoms associated with recurrent posterior subluxation of the shoulder. It can provide predictable success in the setting of unidirectional, nonvoluntary posterior instability without prior surgery.     

Arthroscopic management of posterior shoulder instability

The etiology of posterior shoulder instability is multifactorial. Similarly, the surgical treatment of posterior shoulder instability requires more than one management technique. During the past 7 years we have used an anatomic specific approach to posterior shoulder instability, relying on physical examination and diagnostic arthroscopy to determine the correct repair technique. This study reports our results with 61 consecutive patients with refractory posterior shoulder instability requiring surgical correction. In each instance, the specific pathologic entity causing instability was corrected in an anatomic specific approach to the disorder. All patients were re-evaluated 1 to 6 years postoperatively (mean, 34 months). Fifty-five of 61 patients maintained stable shoulders, indicating a 90% success rate with this approach to posterior instability. We would recommend this approach in the management of posterior shoulder instability refractory to rehabilitative treatment.     

Arthroscopic stabilization of posterior shoulder instability

Posterior shoulder instability is a rare and challenging condition with a complex patho-anatomy. The role of arthroscopic repair in the treatment remains poorly defined. The purpose of this study is to evaluate the result of arthroscopic stabilization procedures in patients with posterior shoulder instability. In this case series, we treated eighteen patients (19 shoulders) with posterior shoulder instability with either arthroscopic thermal capsular shrinkage (9 patients), capsulorrhaphy (3) or labral refixation (7). There were eight male and ten female patients with a mean age of 26 years. The study group included unidirectional (6 patients; PI), bi-directional (8; PII) and multidirectional posterior instability (5; MDI). The Rowe-score and DASH-score as well as subjective and objective evaluations of the patients function, range of motion, pain and instability were used as clinical outcome measurements. At a mean follow-up of 50 months, the Rowe-score improved significantly from 46 to 74 (P = 0.005). Four patients (21%) had recurrent instability after arthroscopic treatment (2 with generalized ligamentous laxity; 3 after thermal shrinkage). Analysis of postoperative DASH-scores showed a tendency toward inferior outcomes after thermal shrinkage and in patients with an a-traumatic origin of shoulder instability. We conclude that arthroscopic shoulder stabilization by either labral refixation or capsulorrhaphy is a safe and effective treatment for posterior shoulder instability. Thermal capsular shrinkage however showed poor results and should be abandoned for this indication.     

Operative stabilization of posterior shoulder instability

BACKGROUND: Symptomatic, traumatic posterior shoulder instability is often the result of a posteriorly directed blow to an adducted, internally rotated, and forward-flexed upper extremity. Operative repair has been shown to provide favorable results. Current arthroscopic techniques with suture anchors and the ability to plicate the capsule using a nonabsorbable suture may provide favorable outcomes with reduced morbidity. PURPOSE: To evaluate the results of operative shoulder stabilization in patients with traumatic posterior shoulder instability. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A consecutive series of patients who underwent arthroscopic or open posterior stabilization for traumatic posterior shoulder instability were evaluated using subjective assessments, physical examinations, the Single Assessment Numeric Evaluation, Rowe score, Simple Shoulder Test, and the Western Ontario Shoulder Instability Index.Results: Between May 1996 and February 2002, 31 shoulders (30 patients) underwent posterior stabilization (19 arthroscopically, 12 open). There were 29 men and 1 woman (mean age, 23 years). Preoperatively, all patients had a distinct traumatic cause for the instability. On physical examination, all patients had posterior apprehension and increased (2+, 3+) posterior load-shift testing. Preoperative radiographs and/or magnetic resonance imaging revealed posterior rim calcification or reverse Bankart lesions in 29 cases (94%). At arthroscopy, posterior labral injuries, reverse Bankart lesions, or humeral head defects were identified. Follow-up averaged 40 months, and the mean duration between injury and surgery was 21 months. The mean Single Assessment Numeric Evaluation, Rowe score, Simple Shoulder Test, and Western Ontario Shoulder Instability Index scores, respectively, for the entire group were 89, 87, 11, and 346; for the open group, they were 81, 80, 10.5, and 594; for the arthroscopic group, they were 92, 92, 11.4, and 190. The Western Ontario Shoulder Instability Index (P < .03) and Rowe score (P < .04) outcomes scores for the arthroscopic group were statistically better than those of the open group. Twenty-nine of 31 shoulders were rated as excellent or good. CONCLUSION: In the case of traumatic posterior shoulder subluxation, posterior lesions of the labrum ("reverse Bankart"), articular edge, and capsule are observed. Surgical treatment addressing these lesions led to satisfactory results for both the open and arthroscopic treated groups. In this study, an arthroscopic technique utilizing suture anchor repair with capsular placation provided the most favorable outcomes.     

Arthroscopic repair for traumatic posterior shoulder instability

BACKGROUND: The role of arthroscopic repair in the treatment of posterior shoulder instability remains poorly defined. PURPOSE: To evaluate the results of arthroscopic repair of posterior Bankart lesions. STUDY DESIGN: Retrospective review. METHODS: Records were reviewed of 27 shoulders (26 patients). All of the patients were male with a mean age of 28.7 years; in all cases symptoms were preceded by a traumatic event. Fourteen of the patients had 2+ to 3+ posterior translation noted under preoperative anesthesia. The posterior capsulolabral complex was found to be detached from the glenoid rim in all cases; bioabsorbable tack fixation was used for repair. RESULTS: At a mean follow-up of 5.1 years, no patients demonstrated a range of motion deficit. Muscle weakness (grade 4/5) in external rotation was noted in two patients (8%). There was no instability greater than 1+ in the anterior, posterior, or inferior directions. The mean L'Insalata shoulder score was 90.0 +/- 13.9. The mean SF-36 physical and mental component scores were 50.4 +/- 7 and 53.9 +/- 9, respectively. Symptoms of pain and instability were eliminated in 24 patients (92%). Two patients (8%) required additional surgery after arthroscopic repair of the posterior Bankart lesion. Radiographs demonstrated that there had been no progressive glenohumeral joint degeneration. CONCLUSIONS: Arthroscopic repair of the posterior capsulolabral complex is an effective means of eliminating symptoms of pain and instability associated with posterior Bankart lesions of traumatic origin.     

Posterior bone block procedure for posterior shoulder instability

The posterior bone block procedure is an uncommon surgical procedure used in the treatment of posterior shoulder instability. The purpose of this study is to report the results of the posterior bone block procedure in the treatment of posterior shoulder instability. We retrospectively reviewed 21 shoulders that had undergone a posterior bone block procedure in the treatment of recurrent posterior shoulder instability between 1984 and 2001. Fifteen patients (16 shoulders) had a prior traumatic posterior glenohumeral dislocation and 5 patients (5 shoulders) had a prior traumatic posterior glenohumeral subluxation. The mean age at surgery was 24.8 years (range 17–40 years). Patients were evaluated with the Constant score, the Duplay score, a subjective result, and radiography. Preoperatively, ten shoulders had glenoid fractures, two shoulders had loss of the normal contour of the posterior osseous glenoid, and ten shoulders had humeral head impaction fractures (reverse Hill-Sachs lesion). Seventeen shoulders underwent preoperative computed tomography and had average glenoid retroversion of 9.6° (range 0–21°). At an average follow-up of 6 years, all patients reported their subjective results as good or excellent. At follow-up the mean Constant score was 93.3 points (range 80–103 points), and the mean Duplay score was 85.6 points (range 40–100 points). Fifteen patients returned to sports at their pre-injury level. Three patients were considered clinical failures; one with a recurrent posterior dislocation and two with substantial posterior apprehension on follow-up examination. Two shoulders had glenohumeral arthritis on radiographs at the latest follow-up. The posterior bone block is a good treatment option for posterior dislocation. The risk of recurrent dislocation is low following this procedure.     

Evaluation and treatment of shoulder instability

The shoulder joint has a wide range of motion as a result of a complex interplay of soft tissue and bone structures. It is also the most frequently dislocated joint in the body. Shoulder dislocations are generally classified as traumatic and nontraumatic. There are many specific causes, each of which necessitate individualized treatment modalities. Accurate diagnosis requires a careful history and physical examination. Arthroscopic surgery and advances in imaging have expanded our understanding of anatomy and pathology relevant to shoulder instability and its treatment. Surgery is the treatment of choice for recurrent traumatic instability. Surgery may also be indicated in some first-time traumatic dislocations in young contact athletes, whereas rehabilitation is the initial treatment of choice in older patients with initial instability and in those with nontraumatic dislocations. Results of arthroscopic capsulolabral repair now equal those of open capsulolabral repair and have become the surgical treatment of choice for most patients. However, in cases of recurrent instability and significant bone deficiency of either the glenoid or humeral head, open bone reconstructive procedures are often necessary to ensure successful outcomes.     

Thermal capsulorrhaphy for the treatment of shoulder instability

Thermal capsulorrhaphy has been used to treat many different types of shoulder instability, including multidirectional instability, unidirectional instability, and microinstability in overhead-throwing athletes. A device that delivers laser energy or radiofrequency energy to the capsule tissue causes the collagen to denature and the capsule to shrink. The optimal temperature to achieve the most shrinkage without causing necrosis of the tissue is between 65 degrees and 75 degrees centigrade. This treatment causes a significant decrease in mechanical stiffness for the first 2 weeks, and then, after the tissue undergoes active cellular repair from the surrounding uninjured tissue, the mechanical properties return to near normal by 12 weeks. If the thermal energy is applied in a grid pattern, then the tissue heals with more stiffness by 6 weeks. Clinical studies on thermal capsulorrhaphy for the treatment of multidirectional instability have shown a high rate of recurrent instability (12%-64%). The clinical studies on unidirectional instability showed much better recurrence rates (4%-25%), but because most of the patients also underwent concomitant Bankart repairs and superior labral anterior posterior lesion repairs, the efficacy of the thermal treatment cannot be ascertained. A randomized controlled trial would be needed to assess whether instability with Bankart lesions requires augmentation with thermal capsulorrhaphy. For the patients with microinstability who are overhead-throwing athletes, thermal capsulorrhaphy has shown varying results from a 97% rate of return to sports to a 62% rate of return to sports. Complications of this technique include temporary nerve injuries that usually involve the sensory branch of the axillary nerve and thermal necrosis of the capsule, which is rare.     

Modified arthroscopic McLaughlin procedure for treatment of posterior instability of the shoulder with an associated reverse Hill-Sachs lesion

Traumatic posterior shoulder dislocations are often accompanied by an impression fracture on the anterior surface of the humeral head known as a “reverse Hill-Sachs lesion”. This bony defect can engage on the posterior glenoid rim and subsequently lead to recurrent instability and progressive joint destruction. We describe a new modified arthroscopic McLaughlin procedure, which allows for filling of the bony defect with the subscapularis tendon and subsequently prevents recurrence of posterior instability. This technique creates a double-mattress suture providing a large footprint for the subscapularis and a broader surface area to allow for effective tendon to bone healing. Furthermore, it obviates the need for detaching the subscapularis tendon and avoids the morbidity potentially associated with open procedures. Level of evidence V.     

Open repairs for the treatment of anterior shoulder instability

Successful treatment of anterior instability of the shoulder requires a balance between restoring joint stability and minimizing loss of glenohumeral motion. The choice of treatment should be individualized on the basis of the patient's occupation and level of participation in sports, as well as on the degree of instability of the shoulder. Despite discussions to the contrary, there is no single "essential lesion," as proposed by Bankart, that is responsible for recurrent anterior shoulder instability, although the Bankart lesion is by far the most important. The choice of operative treatment must be tailored to correct the abnormality that is identified at the time of surgery. A variety of promising arthroscopic techniques have been developed for the treatment of anterior shoulder instability; however, open stabilization remains the standard, especially for severe instabilities, revision procedures, and for athletes who participate in contact sports. This article will review the open surgical techniques used for treatment of anterior instability of the shoulder. Both current and historical operations will be discussed. Regardless of which procedure is chosen by a surgeon, the treatment should follow the guidelines taught by Rowe: anatomic dissection at the time of surgery, identification and repair of the lesions responsible for the instability, returning tissues to their anatomic locations, and early postoperative range of motion. By following these guidelines, the results of treatment of anterior instability of the shoulder can be optimized.     

Posterior glenoid rim deficiency in recurrent (atraumatic) posterior shoulder instability

Objective. To assess the shape of the posterior glenoid rim in patients with recurrent (atraumatic) posterior instability. Design and patients.CT examinations of 15 shoulders with recurrent (atraumatic) posterior instability were reviewed in masked fashion with regard to abnormalities of the glenoid shape, specifically of its posterior rim. The glenoid version was also assessed. The findings were compared with the findings in 15 shoulders with recurrent anterior shoulder instability and 15 shoulders without instability. For all patients, surgical correlation was available. Results.Fourteen of the 15 (93%) shoulders with recurrent (atraumatic) posterior shoulder instability had a deficiency of the posteroinferior glenoid rim. In patients with recurrent anterior instability or stable shoulders such deficiencies were less common (60% and 73%, respectively). The craniocaudal length of the deficiencies was largest in patients with posterior instability. When a posteroinferior deficiency with a craniocaudal length of 12 mm or more was defined as abnormal, sensitivity and specificity for diagnosing recurrent (atraumatic) posterior instability were 86.7% and 83.3%, respectively. There was a statistically significant difference in glenoid version between shoulders with posterior instability and stable shoulders (P=0.01). Conclusion.Recurrent (atraumatic) posterior shoulder instability should be considered in patients with a bony deficiency of the posteroinferior glenoid rim with a craniocaudal length of more than 12 mm. Received: 13 September 1999 Revision requested: 9 November 1999 Revision received: 13 December 1999 Accepted: 4 January 2000     

Monopolar electrothermal arthroscopy for treatment of shoulder instability in the athlete

Arthroscopic stabilization of the shoulder has gained considerable interest as a treatment alternative for shoulder instability in athletes. Basic science and clinical studies are helping to define the ideal patient population, surgical techniques, and rehabilitation protocols that will enhance our surgical results and maximize patient satisfaction. We describe here our surgical program, basic science foundation, and early clinical results.[/]ab     

Electromyographic analysis of muscle action about the shoulder

The application of dynamic integrated EMG and motion analysis to the shoulder has improved the understanding of dynamic shoulder biomechanics during athletic activities and rehabilitation protocols. These studies exemplify a symbiotic merger of basic science research and clinical application. EMG and motion analysis has produced specific objective quantifiable data concerning the muscles in and about the shoulder during normal planar motion, athletic motions, and rehabilitation exercises. This expanded understanding of intricate muscular interrelationships during athletic activities and rehabilitative exercises has not only complemented clinical awareness of subtle shoulder anomalies but helped to develop logical preventative exercises, surgical procedures, and rehabilitation protocols, all of which are based on sound scientific principles. Comprehension of the normal intermuscular interdependence during the previously mentioned activities has led us to investigate common athletic shoulder disorders. It is hoped that application of the normal EMG and motion analysis to the pathologic state will enable us to suggest new ideas concerning the pathomechanics of these disorders, as well as propose future treatment and rehabilitation of these maladies. The specific emphasis in this article has been the role of integrated EMG and motion analysis in the evaluation of athletic activities and rehabilitation exercises. It is hoped that knowledge of these investigations will increase the clinician's basic understanding of the biomechanics of the shoulder and aid in his or her clinical evaluation, treatment, and subsequent rehabilitation of the shoulder.     

Arthroscopic treatment of posterior and multidirectional instability

The author can answer the three fundamental questions which were posed in the beginning of this chapter as follows: Atraumatic posterior and multidirectional laxity is attributable to capsular ligamentous laxity and can be asymptomatic initially. Over the time, repetitive subluxation of the humeral head exerts excessive rim-loading on the posteroinferior glenoid labrum which can develop into retroversion of the glenoid labrum and eventually leading to labral tears. In this stage, a patient develops shoulder pain during daily and sports activities. Besides increased translation, the diagnosis should be based on the symptoms reproduced by the jerk and Kim tests. The jerk test is a hallmark for predicting the prognosis of nonoperative treatment in posteroinferior instability. Shoulders with a painful jerk test have posteroinferior labral lesion and are unresponsive to nonoperative treatment. In these patients, early surgery may be indicated. Any successful surgical procedure should correct both the capsular laxity and the retroversion of the posteroinferior glenoid labrum. Simple capsular plication or an inferior capsular shift is insufficient for correcting the two major pathologies. Arthroscopic capsulolabroplasty restores capsular tension as well as labral height.     

Current concepts in the diagnosis and treatment of shoulder instability in athletes

Glenohumeral joint instability is a fairly common clinical disorder in athletes, especially in sports that involve the throwing motion. The direction of shoulder instability can be anterior, inferior, posterior, or multidirectional. The cause can be trauma, congenital laxity, or voluntary muscle action. Normal shoulders that have been disrupted by injury respond well to surgical correction. Shoulders that have inherently lax supporting structures, as found in patients with atraumatic and voluntary dislocation, have less consistent success with surgical repair. A common condition encountered in the shoulder of a throwing arm is anterior subluxation, which can be diagnosed by the positive apprehension sign and confirmed by arthroscopy. A torn glenoid labrum is a common injury also. Improvement in the diagnosis and treatment of shoulder disorders has been made recently by arthroscopy which allows direct visualization of the joint; many conditions can now be corrected by means of arthroscopic surgery. Radiographic techniques have also been improved.     

Electromyographic analysis of the shoulder during the golf swing

Golf is a popular sport throughout the world, yet there is little in the literature that discusses the mechanics of the swing. The purpose of this study is to analyze the EMG activity in eight shoulder muscles of both the right and left arms during the golf swing. The results reveal that the infraspinatus and supraspinatus act predominantly at the extremes of shoulder range of motion, the subscapularis and pectoralis major during acceleration, the latissimus dorsi during forward swing, and the anterior deltoid during forward swing and follow-through. The middle and posterior deltoids appear to be relatively noncontributory, without any specific timing patterns. This data is an expansion of an earlier pilot study and allows us to more accurately develop an exercise program for optimal performance as well as for prevention and rehabilitation.     

Developments in Bankart repair for treatment of anterior instability of the shoulder

In the past 10 years, Bankart repair for operative treatment of recurrent luxation of the shoulder has become well established. Recently, the arthroscopic Bankart procedure has been developed. Since 1991, cannulated, bioabsorbable plugs are being used (Suretac; Acufex Microsurgical, Mansfield, Ma., USA). This investigation examines what the advantages of this micro-invasive technique are compared with the open Bankart procedure. From 1986 to 1995, 120 patients underwent Bankart repair of the shoulder in our hospital. Since 1993 we have preferred using arthroscopy, and since 1994 with Suretac. We were able to follow-up 93 patients. The results were assessed using the criteria of stability, range of motion, pain and functional results. The patients were evaluated using the Rowe score. The mean follow-up time was much shorter in the arthroscopic group. Nevertheless, we registered a higher reluxation rate (2 patients, 8%) in comparison with the group that underwent open surgery (3 patients, 4%). As postoperative pain and deterioration of range of motion are less, however, the mean Rowe score shows no significant difference. In conclusion, proper selection of patients has to be performed: arthroscopic Bankart repair is recommended for refixation of a detached anterior labrum. It is disadvantageous when the labrum is degenerated or the capsular tissue is attenuated. That is why, in our opinion, the open Bankart procedure with its capsulorrhaphy cannot be renounced completely.