Infraspinatus muscle-splitting incision in posterior shoulder surgery. An anatomic and electromyographic study

Suprascapular Neuropathy around the Shoulder: A Current Concept Review

Suprascapular neuropathy is an uncommon but increasingly recognized cause of shoulder pain and dysfunction due to nerve entrapment. The aim of this review is to summarize some important aspects of this shoulder pathology. An extensive research was performed on PubMed and Clinical Key. The goal was to collect all the anatomical, biomechanical and clinical studies to conduct an extensive overview of the issue. Attention was focused on researching the state of art of the diagnosis and treatment. A total of 59 studies were found suitable and included. This condition is more frequently diagnosed in over-head athletes or patients with massive rotator cuff tears. Diagnosis may be complex, whereas its treatment is safe, and it has a great success rate. Prompt diagnosis is crucial as chronic conditions have worse outcomes compared to acute lesions. Proper instrumental evaluation and imaging are essential. Dynamic compression must initially be treated non-operatively. If there is no improvement, surgical release should be considered. On the other hand, soft tissue lesions may first be treated non-operatively. However, surgical treatment by arthroscopic means is advisable when possible as it represents the gold standard therapy. Other concomitant shoulder lesions must be recognized and treated accordingly.

Anatomy of the Scapula Applied to the Posterior Surgical Approach: Safety Parameters during Access to the Lateral Angle

Objective  The objective of this paper was to identify safety parameters in the posterior surgical approach of the scapula through a cross-sectional cadaver study.

Methods  Thirteen cadaver shoulders with no history of surgery or prior musculoskeletal dysfunction, with mean age, weight, and height of 70.1 years, 61.5 kg, and 1.64 m, respectively, were dissected. The anatomic landmark of the studied pathway (infraglenoid tubercle) and its distance to the axillary and suprascapular nerves were measured.

Results  The mean distance between the infraglenoid tubercle (IT) and the axillary nerve (AN) was 23.8 mm, and the mean distance from the IT to the suprascapular nerve (SN) was 33.2 mm.

Conclusion  The posterior approach may be considered safe through the interval between the infraspinatus and teres minor. However, caution should be taken during muscle spacing because of the short distance between the fracture site and the location of the SN and AN. These precautions help to avoid major postoperative complications.

Functional outcomes and clinical strength assessment after infraspinatus-sparing surgical approach to scapular fracture: Does it really make a difference?

Background

Surgical treatment of scapular fractures with posterior approach is frequently associated with postoperative infraspinatus hypotrophy and weakness. The aim of this retrospective study is to compare infraspinatus strength and functional outcomes in patients treated with the classic Judet versus modified Judet approach for scapular fracture.

Patients and methods

20 cases with scapular neck and body fracture treated with posterior approach for lateral border plate fixation were reviewed. In 11 of 20 cases, we used the modified Judet approach (MJ group), and in 9 cases we used the classic Judet approach (CJ group). All fractures were classified according to the AO classification system. At follow-up examinations, patients had X-ray assessment with acromiohumeral distance (AHD) measurement, clinical evaluation, active range of motion (ROM) examination, Constant Shoulder Score, and Disability of the Arm, Shoulder and Hand (DASH) Score. Infraspinatus strength assessment was measured using a dynamometer during infraspinatus strength test (IST) and infraspinatus scapular retraction test (ISRT).

Results

Demographic data did not significantly differ between the CJ group and MJ group, except for mean follow-up, which was 4.15 years in the CJ group and 2.33 in the MJ group (p < 0.001). All X-ray examinations showed fracture healing. AHD was significantly decreased in the CJ group (p = 0.006). We did not find significant differences in active ROM between the MJ and CJ groups in the injured arm (p < 0.05). The Constant Score was 75.83 (±14.03) in the CJ group and 82.75 (±10.72) in the MJ group (p = 0.31); DASH Score was 10.16 in the CJ group and 6.25 in the MJ group (p = 0.49). IST showed mean strength of 8.38 kg (±1.75) in the MJ group and 4.61 kg (±1.98) in the CJ group (p = 0.002), ISRT test was 8.7 (±1.64) in the MJ group and 4.95 (±2.1) in the CJ group (p = 0.002). Infraspinatus hypotrophy was detected during inspection in six patients (five in the CJ group and one in the MJ group); it was related to infraspinatus strength weakness in IST and ISRT (p < 0.001).

Conclusions

Infraspinatus-sparing surgical approach for scapular fracture avoids infraspinatus hypotrophy and external-rotation strength weakness. We suggest use of the modified Judet approach for scapular fracture and to restrict the classic Judet approach to only when the surgeon believes that the fracture is not easily reducible with a narrower exposure.

Level of evidence

Level IV.

A Reverse Judet approach to the scapula

Fractures of the scapular body that extend to involve the neck and glenoid articular surface with a large gap pose a significant problem for surgical exposure. Several surgical approaches for scapula fixation have been described, but all give limited exposure to the entire scapular body, neck and articular surface. Here, we describe our 'Reverse Judet' technique, with cadaveric dissections and discuss a clinical case. We believe this approach gives a wide exposure of the infraspinous scapular body, neck and glenoid articular surface while keeping away from vital neural structures.

The posterior ridge of the greater tuberosity of the humerus: a suitable landmark for the posterior approach to the shoulder joint?

BACKGROUND

The purpose of this study was to evaluate the posterior ridge of the greater tuberosity, a palpable prominence during surgery, as a landmark for the posterior approach to the glenohumeral joint.

METHODS

Twenty-five human cadaveric shoulders were dissected. In 5 cases, a full-thickness rotator cuff tear was present. The posterior surgical anatomy was defined, and the distance from the ridge to the interval between the infraspinatus (IS) and teres minor (TM) muscle, the distance from the ridge to the inferior border of the glenoid (IBG), and the distance between the IS-TM interval and the IBG were determined.

RESULTS

In all specimens, a prominent ridge on the posterior greater tuberosity lateral to the articular margin could be identified. The IS-TM interval was located, on average, 3 mm proximal to this ridge. The IS-TM interval corresponded to a point 5 mm proximal to the IBG. In all shoulders, the ridge was located, on average, 8 mm proximal to the IBG. The plane of the IS-TM interval showed a vertically oblique direction.

CONCLUSION

The posterior ridge of the greater tuberosity is a suitable landmark to locate the internervous plane between the IS and TM and should not be crossed distally. Unlike other landmarks, the ridge moves with the humeral head, making it is less dependent on the patient's size, sex, and arm position and the quality of the rotator cuff. The ridge is always located proximal to the insertion of the TM and IBG.

Suprascapular Nerve Pathology: A Review of the Literature

Background:

Suprascapular nerve pathology is a rare diagnosis that is increasingly gaining popularity among the conditions that cause shoulder pain and dysfunction. The suprascapular nerve passes through several osseoligamentous structures and can be compressed in several locations.

Methods:

A thorough literature search was performed using online available databases in order to carefully define the pathophysiology and to guide diagnosis and treatment.

Results:

Suprascapular neuropathy diagnosis is based on a careful history and a thorough clinical and radiological examination. Although the incidence and prevalence of the condition remain unknown, it is highly diagnosed in specific groups (overhead athletes, patients with a massive rotator cuff tear) probably due to higher interest. The location and the etiology of the compression are those that define the treatment modality.

Conclusion:

Suprascapular neuropathy diagnosis is based on a careful history and a thorough clinical and radiological examination. The purpose of this article is to describe the anatomy of the suprascapular nerve, to define the pathophysiology of suprascapular neuropathy and to present methodically the current diagnostic and treatment strategies.

An anatomical investigation of clock face landmarks around the glenoid for shoulder arthroscopy orientation

BACKGROUND

For shoulder arthroscopy, few anatomical landmarks are available and inexperienced surgeons tend to be adrift due to the limited visual field of the scope. The purpose of this study was to demonstrate the useful landmarks around the glenoid for accurate orientation, and also the safe distance to avoid suprascapular nerve injury during surgical procedures around the glenoid.

METHODS

In 15 human solution-fixed cadavers, a cross-section of the shoulder joint on the labrum surface was created. The positions of the principal anatomical structures surrounding the glenoid were marked on the labrum and measured using our clock face indication system. In 9 shoulders the distances from the labral surface to the spinoglenoid notch were recorded. As an indicator of the scapula size, the distances between the superior and inferior angles of the scapula were also measured.

RESULTS

The average landmark positions in the right shoulder were as follows: center of the attachment of the long tendon 11:59, anterior edge of the supraspinatus 11:59, posterior edge of the base of the coracoid process 12:13, superior edge of the subscapularis 1:03, anterior edge of the base of the coracoid process 1:25, inferior edge of the subscapularis 5:27, inferior edge of the teres minor 6:21, border of the infraspinatus and teres minor 7:43, center of the scapula spine 10:06, border of the supra and infraspinatus 10:27. The average distance from the labral surface to the spinoglenoid notch was 23.17 mm, and that from the superior to inferior angle was 144.93 mm. The Pearson correlation coefficient for these distances was 0.007.

CONCLUSIONS

The locations of anatomical landmarks surrounding the glenoid were reliably demonstrated using our clock face indication system. The expected distance from the labral surface to the suprascapular nerve was approximately 23 mm, irrespective of the size of the scapula.

Morphometry of the suprascapular notch: correlation with scapular dimensions and clinical relevance

Background

Better knowledge of the suprascapular notch anatomy may help to prevent and to assess more accurately suprascapular nerve entrapment syndrome. Our purposes were to verify the reliability of the existing data, to assess the differences between the two genders, to verify the correlation between the dimensions of the scapula and the suprascapular notch, and to investigate the relationship between the suprascapular notch and the postero-superior limit of the safe zone for the suprascapular nerve.

Methods

We examined 500 dried scapulae, measuring seven distances related to the scapular body and suprascapular notch; they were also catalogued according to gender, age and side. Suprascapular notch was classified in accordance with Rengachary’s method. For each class, we also took into consideration the width/depth ratio. Furthermore, Pearson's correlation was calculated.

Results

The frequencies were: Type I 12.4%, Type II 19.8%, Type III 22.8%, Type IV 31.1%, Type V 10.2%, Type VI 3.6%. Width and depth did not demonstrate a statistical significant difference when analyzed according to gender and side; however, a significant difference was found between the depth means elaborated according to median age (73 y.o.). Correlation indexes were weak or not statistically significant. The differences among the postero-superior limits of the safe zone in the six types of notches was not statistically significant.

Conclusions

Patient’s characteristics (gender, age and scapular dimensions) are not related to the characteristics of the suprascapular notch (dimensions and Type); our data suggest that the entrapment syndrome is more likely to be associated with a Type III notch because of its specific features.

Arthroscopic "cuff-sparing" percutaneous (CUSP) technique for posterior instability repair in the beach-chair position

Arthroscopic posterior labral repair and capsular shift procedures are technically difficult in the beach-chair position as compared with the lateral decubitus position. Optimal visualization in the beach-chair position, and anchor placement in the posterior glenoid rim, necessitate various lateral trans-cuff portals, and these may result in damage to the rotator cuff tendons. The author has devised a new technique for posterior labral repair in the beach-chair position; the technique involves visualization of the posterior capsulolabral complex through a 70-degree arthroscope placed in the posterior axillary pouch portal, and labral repair is performed through percutaneous medial portals. The cuff-sparing and percutaneous (CUSP) nature of the technique utilizes safe anatomic zones for visualization and percutaneous repair of the entire posterior labrum, and lateral portals that may potentially damage the rotator cuff tendons are avoided. Technical variants of the procedure include: (1) a "CUSP shift" technique (combined labral repair and capsular shift); (2) a "CUSP-stitch" technique (isolated labral repair without a capsular shift); and (3) a "posterior labroplasty" technique for reconstruction of deficient posterior labral tissue. Technical tips to avoid neurological injury, and a detailed rehabilitation protocol are presented.

The safe zone for avoiding suprascapular nerve injury during shoulder arthroscopy: an anatomical study on 500 dry scapulae

HYPOTHESIS/BACKGROUND

Suprascapular nerve injury may be a complication during shoulder arthroscopy. Our aim was to verify the reliability of the existing data, assess the differences between scapulae in the 2 genders and in the same subject, obtain a safe zone useful to avoid iatrogenic nerve lesions, and analyze the existing correlations between the scapular dimensions and the safe zone.

METHODS

We examined 500 dried scapulae, measuring 6 distances for each one, referring to the scapular body, glenoid, and the course of the suprascapular nerve, also catalogued according to gender and side. Differences due to gender were assessed comparing mean ± sd of each distance in males and females; paired t test was used to compare distances deriving from each couple. Successively, we calculated our safe zone and Pearson's correlation.

RESULTS

We found nonsignificant differences between the right and left distances deriving from each couple; differences due to gender were stated. We defined 3 kinds of safe zones referring to: 500 scapulae; males (139 scapulae) and females (147 scapulae). The correlation indexes calculated between the axis of the scapular body and glenoid, and the posterosuperior distance (referring to the suprascapular nerve) were 0.624, 0.694, 0.675, 0.638; while those with the posterior distance were 0.230, 0.294, 0.232, 0.284.

DISCUSSION/CONCLUSIONS

Knowledge of the safe zone, for avoiding suprascapular nerve injury, is important; gender and specific scapular dimensions should be evaluated, as they influence the dimensions of the safe zone. The linear predictors should be used to obtain specific values of the posterosuperior limit in each patient.

Medial perforation of the glenoid neck following SLAP repair places the suprascapular nerve at risk: a cadaveric study

BACKGROUND

Although suprascapular nerve injury after SLAP (superior labrum anterior to posterior) repair has rarely been reported, the direction of anchor insertion is toward the suprascapular nerve. The purpose of this study was to evaluate the risk of suprascapular nerve injury during the drilling and anchor insertion for anterior SLAP repair.

MATERIALS AND METHODS

Twelve cadaveric shoulders were mounted in a lateral decubitus position (to mimic actual surgery) and 1 suture anchor for anterior SLAP repair was inserted arthroscopically from the anterior portal at 00:30-1:00 o'clock in right shoulders (11-11:30 in left). Then, cadaveric shoulders were dissected to determine the pathway of suprascapular nerve, the location of suture anchor, and anchor perforation of the glenoid wall. Distances from suprascapular nerve to suture anchor tips (which perforated medial cortex of glenoid)-that is, nerve-anchor interval (NAI)--were measured. Glenoid widths and heights were also measured to evaluate the correlation between glenoid areas and NAI. Depth of drilling was also determined.

RESULTS

All suture anchors perforated the glenoid wall. Mean drill depth was 14.2 (±2.8) mm and mean NAI was 3.1 (±2.7) mm. In 4 shoulders, suture anchor tips contacted the suprascapular nerve. The mean height of the glenoid surface was 30.0 mm (±2.5), its mean width was 22.9 mm (±1.9), and its mean area was 2164.3 mm(2) (±334.1). No correlation was found between glenoid areas and NAI (P = .277).

CONCLUSION

Suprascapular nerve lies very close to drilling sites and suture anchors during arthroscopic anterior SLAP repair. The present study cautions that care should be taken when anterior anchors are being inserted.

Suprascapular neuropathy

Suprascapular neuropathy is a relatively uncommon but significant cause of shoulder pain and dysfunction. The suprascapular nerve follows a tortuous course from the neck to the posterior shoulder. There are several potential causes of nerve entrapment along this path, particularly at the vulnerable suprascapular and spinoglenoid notches, where nerve excursion is limited by bony and ligamentous constraints. Additional extrinsic compression may be caused by glenohumeral joint-related ganglion cysts or soft-tissue masses. Traction neuropathy may occur following excessive nerve excursion during overhead sports or as a result of massive, retracted rotator cuff tears in older patients. Diagnosis is based on a careful history, physical examination, focused imaging, and electrodiagnostic studies. In the absence of a clear structural compression or overtensioning of the nerve, treatment initially should be nonsurgical, with activity modification and physical therapy. Discrete nerve compression or failure of nonsurgical measures warrants early surgical intervention. Arthroscopic alternatives to the traditional open suprascapular and/or spinoglenoid notch decompressions have the benefit of simultaneously diagnosing and addressing intra-articular and/or subacromial pathology while minimizing morbidity. In most patients, both open and arthroscopic approaches provide reliable pain relief and improvements in function; return of strength and muscle bulk is less predictable.

Rehabilitation and functional outcomes in collegiate wrestlers following a posterior shoulder stabilization procedure

STUDY DESIGN

Case series.

CASE DESCRIPTION

Five consecutive collegiate Division I wrestlers, with a mean age of 20.2 years (range, 18-22 years), were treated postsurgical stabilization to address posterior glenohumeral joint instability. All received physical therapy postoperatively, consisting of range-ofmotion, strengthening, and plyometrics exercises, neuromuscular re-education, and sport-specific training. Functional outcome scores using the Penn Shoulder Score questionnaire were recorded at postsurgical initial evaluation and discharge. Isometric shoulder strength, measured with a handheld dynamometer at discharge, was compared with measurements made during preseason screening.

OUTCOMES

Postsurgery, upon initial physical therapy evaluation, scores on the Penn Shoulder Score questionnaire ranged from 37 to 74 out of 100. All 5 wrestlers improved with rehabilitation such that their scores at discharge ranged from 81 to 91 out of 100. Mean external rotation-internal rotation strength ratio for the involved shoulder was 73.5% (range, 55.9%-88.7%) preseason and 80.9% (range, 70.2%-104.1%) postrehabilitation. Four patients were able to return to wrestling over a period of 1 season, with no episodes of reinjury to their surgically repaired shoulder.

DISCUSSION

Current research on posterior glenohumeral instability is limited, due to the relatively rare diagnosis and infrequent need for surgical intervention. Providing a structured physical therapy program following this surgical procedure appeared to have assisted in a return to full functional activities and sports.

LEVEL OF EVIDENCE

Therapy, level 4. J Orthop Sports Phys Ther 2009;39(7):550-559, Epub 24 February 2009. doi:10.2519/jospt.2009.2952.

Surgical exposure and fixation of displaced type IV, V, and VI glenoid fractures

Displaced intra-articular fractures of the glenoid are rare and frequently result from high-energy injuries. Types IV, V, and VI fractures have in common a fracture line which extends medially into the scapular body. These fracture patterns present unique challenges for surgical approaches and reduction and fixation strategies. A modified posterior approach allows for the simultaneous exposure of the medial scapular border and the glenoid articular surface. An initial reduction of the medial fracture indirectly restores the scapular relationship, allowing for subsequent completion of the articular reduction via a limited approach to the posterior shoulder using the same incision.

A posterosuperior approach to the shoulder

An approach for a better surgical exposure of the posterior part the glenoid and the rotator cuff is presented as an alternative for the long deltopectoral incision that might be considered in specially selected cases. In shoulder arthroplasty, it can be used for bone grafting to reorient the glenoid, revision of a glenoid component, or repair of a large rotator cuff tear. This posterosuperior approach consists of an osteotomy of the lateral rim and posterior corner of the acromion, with reflection of part of the medial and posterior insertion of the deltoid muscle. A special plate is used for stable fixation of the osteotomy. The method has been used since 1994 for shoulder prosthesis insertion in 79 patients. In 72 patients with a total shoulder or hemiarthroplasty, the cuff was attenuated or ruptured in 24 and could be repaired in 22. Twenty-two patients underwent a bony procedure to reorient the glenoid surface. The average correction of the superior tilt was 7 degrees . The external rotators are released from the bone and reattached, which might result in weakening of external rotation. This possible complication could not be confirmed at follow-up. The osteotomy healed in all but 1 patient. The fixation material had to be removed in 13.

Arthroscopic fixation of the subscapularis tendon in the reverse Hill-Sachs lesion for traumatic unidirectional posterior dislocation of the shoulder

Posterior unidirectional instability of the shoulder following trauma is frequently associated with a cartilage-bone defect on the anterior joint surface of the humeral head. This defect can catch on the posterior joint surface during internal rotation of the arm, which causes redislocation of the humeral head in a posterior direction, thus increasing joint destruction. We describe a new arthroscopic surgical technique in which the subscapularis tendon is mobilized and attached to the defect using nonabsorbable or bioabsorbable suture anchors. In an manner analogous to open surgery with arthrotomy and transposition of the subscapularis tendon insertion into the defect, this arthroscopic technique fills up the defect, blocks extension during internal rotation of the arm, and safely avoids redislocation of the humeral head in a dorsal direction. The arthroscopic technique we describe is easy and safe to perform. Complicated tightening of the posterior joint capsule is no longer necessary following acute injury.

Recurrent posterior shoulder instability

Recurrent posterior shoulder instability is an uncommon, debilitating condition in young adults that is being diagnosed with increasing frequency. Although a number of predisposing factors have been identified, their relative importance remains poorly understood. Poor results have been reported following operative intervention to treat recurrent posterior instability with nonanatomic techniques. The more recent development of lesion-specific surgery has improved clinical results, particularly when that surgery has been performed arthroscopically. Operative treatment is therefore being increasingly recommended at an earlier stage to patients who do not respond to supervised rehabilitation programs.

Open posterior stabilization for recurrent posterior glenohumeral instability

Open posterior capsular shift is used for posterior glenohumeral instability that has failed nonoperative treatment. Few series have fully evaluated the outcome after open posterior stabilization. The purpose of this series was to evaluate the clinical and radiographic outcome after open posterior stabilization of the shoulder. Preoperative and intraoperative factors were analyzed with regard to their impact on results. Forty-eight consecutive shoulders were identified that had undergone primary open shoulder stabilization by use of open posterior capsular shift. Of the shoulders, 4 were lost to follow-up, resulting in a study group of 44 shoulders in 41 patients. Shoulders were evaluated at a range of 1.8 to 22.5 years after surgery by use of the L'Insalata shoulder form, Short Form-36 (SF-36), and a subjective shoulder rating in 44 shoulders. Thirty-nine shoulders were evaluated by physical examination, and thirty-seven underwent radiographic examination. A recurrence of posterior instability occurred in 8 shoulders (19%). Of the patients, 84% were satisfied with the current status of their shoulder. The mean L'Insalata score was 81.25+/-17.8 points, the mean SF-36 physical component score was 50.81+/-7.87, and the mean mental component score was 53.82+/-7.55. Significantly poorer satisfaction and outcome scores were seen in shoulders found to have a chondral defect at the time of stabilization and in patients aged greater than 37 years at the time of surgery. No progressive radiographic signs of glenohumeral arthritis were seen up to 22 years after surgery. Open posterior shoulder stabilization is a reliable procedure for treating significant posterior instability without causing arthritic changes. Patients found to have chondral damage within the shoulder and older patients were found to have less success after stabilization.

A modified judet approach to the scapula

Operative treatment of scapula fractures is uncommon, but is indicated for significantly displaced fractures or intra-articular fractures. This modified Judet approach for exposure of scapula fractures combines several important goals: 1) exposure of all bony elements of the scapula which have adequate bone stock for internal fixation; 2) minimal trauma to the rotator cuff musculature; and 3) protection of the major neurologic structures (suprascapular nerve superiorly and axillary nerve laterally). The main advantage of the exposure is limiting muscular dissection, which can potentially improve rehabilitation and limit morbidity of the operation.

Traitement de l’instabilité postérieure de l’épaule par butée iliaque ou acromiale

PURPOSE OF THE STUDY

The posterior bone block procedure is a popular option for the treatment of involuntary posterior instability of the shoulder. The purpose of this study was to analyze the long-term results of this procedure using an iliac bone graft and to point out the advantages of Kouvalchouk technique using an acromial pediculated block.

MATERIAL AND METHODS

Eighteen patients, ten men and eight women, mean age 27 years, were reviewed: thirteen were active in sports activities including four at the competition level. The duration of symptoms before surgery was four years on the average. One patient experienced recurrent dislocation, twelve suffered regular involuntary subluxation, and five had painful shoulders possibly related to posterior instability considering the arthroscopic findings. For nine patients (group 1), an iliac block was combined with the soft-tissue procedure. In nine others (group 2), the procedure described by Kouvalchouk was used to create a posterolateral acromial bone block with pediculated deltoid fibers. Functional outcome was assessed with the 100-point Duplay score. The position of the bone block and osteoarthritis were assessed on plain x-rays.

RESULTS

Mean follow-up was 13.5 years in group 1 and 3.5 years in group 2. Four patients needed a revision procedure to remove a screw. At last follow-up, the average Duplay score was 78 points. Nine patients returned to their former sports activities. Seven patients were pain free and ten had moderate discomfort at effort. We did not observe any recurrent dislocation no subluxation but did have six patients who described apprehension. The mean Duplay score was 70 points in group 1 and 86 points in group 2. In two patients in group 1, the x-rays showed signs of grade 3 or 4 osteoarthritis, which was related to an intra-articular screw in one; the other patient had had the same degenerative signs before surgery. Two patients developed grade 1 osteoarthritis.

DISCUSSION AND CONCLUSION

The bone block procedure is effective for posterior instability of the shoulder. Occurrence of osteoarthritis, compared with the anterior bone block, is lower after long-term follow-up. The results of the Kouvalchouk procedure with an acromial pediculated bone block look promising. We recommend an additional capsuloplasty when inferior hyperlaxity is associated with posterior instability.

Nerve injury about the shoulder in athletes, part 1: suprascapular nerve and axillary nerve

Nerve injuries about the shoulder in athletes are being recognized with increasing frequency. Prompt and correct diagnosis of these injuries is important to treat the patient and to understand the potential complications and natural history so as to appropriately counsel athletes. This 2-part article is a review and an overview of the current state of knowledge regarding some of the more common nerve injuries seen about the shoulder in athletes.

The posterior branch of the axillary nerve: an anatomic study

BACKGROUND

Surgery on the posterior aspect of the shoulder has become accepted practice for a number of pathological conditions affecting the scapula and the glenohumeral joint. Despite this trend, the anatomy of the posterior branch of the axillary nerve has not been well characterized. The purpose of the present study was to determine the innervation pattern and surgical relationships of the posterior branch of the axillary nerve.

METHODS

Nineteen fresh-frozen human cadaveric forequarter amputation specimens were dissected through a posterior approach. The location of the posterior branch of the axillary nerve and its anatomical relationships with surrounding structures were documented and measured with use of digital calipers.

RESULTS

The posterior branch separated from the main anterior circumflex branch of the axillary nerve immediately anterior to the origin of the long head of the triceps muscle at the six o'clock position on the glenoid. It coursed posteriorly, adjacent to the inferior aspect of the glenoid rim for an average distance of 10 mm (range, 2 to 17 mm) before dividing into the superior-lateral brachial cutaneous nerve and the nerve to the teres minor. The nerve to the teres minor coursed medially along the posterior aspect of the inferior part of the glenoid rim for an average distance of 18 mm (range, 11 to 25 mm) before entering the muscle at its inferior border. The superior-lateral brachial cutaneous nerve coursed inferiorly, deep to the posterior aspect of the deltoid. It became superficial by passing around the medial border of the muscle at an average of 8.7 cm (range, 6.3 to 10.9 cm) inferior to the posterolateral corner of the acromion.

CONCLUSIONS

The posterior branch of the axillary nerve has an intimate association with the inferior aspects of the glenoid and shoulder joint capsule, which may place it at particular risk during capsular plication or thermal shrinkage procedures. The superior-lateral brachial cutaneous nerve and the nerve to the teres minor always arise from the posterior branch. Thus, loss of sensation over the deltoid may indicate loss of teres minor function. The posterior aspect of the deltoid has a more consistent supply from the anterior branch of the axillary nerve, necessitating caution when performing a posterior deltoid-splitting approach to the shoulder.

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.

Injury of the suprascapular nerve in shoulder surgery: an anatomic study

Fifty-two shoulders in 26 cadavers were dissected to evaluate the safe zone for avoiding injury of the suprascapular nerve during open surgical procedures and arthroscopic Bankart repairs requiring blind drilling. The course of the suprascapular nerve was given as the shortest distance between the suprascapular nerve and the glenoid rim. A Kirschner wire was inserted from the anterior glenoid rim toward the suprascapular nerve. The insertion angle toward the suprascapular nerve at the base of the scapular spine in the transverse plane averaged 37.0 degrees and in the sagittal plane averaged 17.5 degrees. The insertion angle toward the bifurcation of the infraspinatus motor branch in the transverse plane averaged 44.3 degrees and in the sagittal plane averaged 27.7 degrees. On the basis of the results of the anatomic evaluation, the safe zone was described. An appreciation of this safe zone may help shoulder surgeons avoid iatrogenic injury to the suprascapular nerve.

Mechanical properties of the posterior rotator cuff

BACKGROUND

The infraspinatus is an important active and passive stabilizer of the glenohumeral joint. It functions as external rotator and participates in elevation of the arm. As its main posterior component, it is frequently involved in rotator cuff tears.

OBJECTIVE

The purpose of this study was to determine the structural and mechanical properties of the infraspinatus tendon structure, including the midsubstance and insertion regions, in the superior, mid-superior, mid-inferior, and inferior portions, in two joint positions.

METHODS

The infraspinatus tendons from 22 fresh frozen cadaver shoulders were divided into four strips. The tendons were held in a cryo-jaw and tested with a material-testing machine in 0 degrees or 60 degrees of glenohumeral abduction corresponding to 90 degrees arm abduction. Ultimate load, displacement and failure mode were recorded. Stiffness, ultimate stress and elastic modulus were calculated.

RESULTS

Significant differences between glenohumeral abduction positions were detected only for the elastic modulus. The mid-superior (676.5 N, S.D. 231.0 N) and the inferior portion (549.9 N, S.D. 284.6 N) had the highest failure loads while the superior (462.8 N, S.D. 237.2 N) and the mid-inferior portions (315.3 N, S.D. 181.5 N) were weaker. Similar trends across the tendon strips were shown for stiffness, ultimate stress and elastic modulus.

RELEVANCE

Position dependent changes in mechanical properties of the infraspinatus tendon probably do not play a role in the pathomechanism of posterior shoulder dislocation. Peaks in stiffness in mid-superior and inferior tendon sections explain the low incidence of posterior dislocations. The low ultimate failure loads in the superior portions might explain the frequent extension of rotator cuff ruptures into the infraspinatus tendon.

Suprascapular neuropathy

Suprascapular neuropathy is an uncommon cause of shoulder pain and weakness and therefore may be overlooked as an etiologic factor. The suprascapular nerve is vulnerable to compression at the suprascapular notch as well as at the spinoglenoid notch. Other causes of suprascapular neuropathy include traction injury at the level of the transverse scapular ligament or the spinoglenoid ligament and direct trauma to the nerve. Sports involving overhead motion, such as tennis, swimming, and weight lifting, may result in traction injury to the suprascapular nerve, leading to dysfunction. The diagnosis of suprascapular neuropathy is based on clinical findings and abnormal electrodiagnostic test results, after the exclusion of other causes of shoulder pain and weakness. Magnetic resonance imaging may provide an anatomic demonstration of nerve entrapment and muscle atrophy. With this modality, ganglion cysts are recognized with increasing frequency as a source of external compression of the suprascapular nerve. Without evidence of a discrete lesion compressing the nerve, nonoperative treatment should include physical therapy and avoidance of precipitating activities. When nonoperative treatment fails to alleviate symptoms or when a discrete lesion such as a ganglion cyst is present, surgical decompression is warranted. Decompression gives reliable pain relief, but recovery of shoulder function and restoration of atrophied muscle tissue may be incomplete.

Open shoulder instability surgery. Complications

Surgical stabilization of the shoulder can be a challenging procedure. Complications can and do occur, even in the hands of the most experienced surgeons. Emphasis must be placed on proper diagnosis, appropriate technique, and an understanding of potential complications to maximize the likelihood of a successful surgical outcome. The authors hope that this review helps to outline the complications that can occur with open instability surgery. Only by understanding the complications associated with the procedures performed can surgeons hope to decrease the frequency of their occurrence.

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.

The spinoglenoid ligament and its relationship to the suprascapular nerve

Entrapment of the suprascapular nerve by the inferior transverse scapular ligament or spinoglenoid ligament (SGL) has been discussed frequently in the literature, but it has not been well documented anatomically. Therefore the mechanism of entrapment is not well understood. When isolated atrophy and denervation of the infraspinatus muscle have been noted, compression of the muscle's motor branch at the spinoglenoid notch has been implicated. This anatomic and morphologic study investigates the role of the SGL in entrapment neuropathy of the infraspinatus. We used 23 shoulders from 19 cadavers, 5 women (8 shoulders) and 14 men (15 shoulders), with a mean age of 67.9 (54 to 78) years. The presence or absence of the SGL was noted. The length, width, and orientation of the SGL; size and shape of the tunnel to the infraspinatus fossa; and distance of the notch to the posterior glenoid rim were determined. The SGL was present in 14 (60.8%) shoulders, 5 (36%) women and 9 (64%) men. The SGL was wider at the superior entrance of the tunnel and fanned and twisted toward the inferior aspect. In all specimens the SGL fibers inserted into the posterior shoulder capsule. The mean length for the upper part of the SGL was 17.5 +/- 2.6 mm in men and 15.8 +/- 1.8 mm in women, and the lower part was 14.1 +/- 2.4 mm and 12.9 +/- 1.8 mm, respectively. The widths of the SGL at the origin of the scapular spine were 12.2 +/- 3.9 mm for men and 10.4 +/- 2.7 mm for women, whereas the insertion site widths were 15.8 +/- 2.2 mm for men, and 16.1 +/- 3.8 mm for women. The midportion width of the SGL was 6.8 +/- 1.9 mm in men and 5.8 +/- 2.1 mm in women. During cross-body adduction and internal rotation of the glenohumeral joint, the interaction of the SGL and the posterior capsule resulted in a tightening of the SGL. The suprascapular nerve moved laterally and stretched underneath the SGL in this position.