Osseous anatomy of the scapula

MR imaging of the rotator cuff

MR imaging is the optimal method for evaluating suspected rotator cuff pathology. Current techniques of fast spin-echo imaging without and with fat suppression allow accurate identification and characterization of tendinous and myotendinous abnormalities of the rotator cuff. Impingement disorders, tendon degeneration, instability,and trauma comprise the multifactorial nature of rotator cuff disease. This article addresses the role of MR imaging in evaluating the rotator cuff and the importance of MR imaging in identifying other lesions that may mimic rotator cuff pathology. A rationale for protocol design, including MR arthrography and the use of specialized positioning, such as abduction and external rotation (ABER), are discussed.

Scapular thickness--implications for fracture fixation

The purpose of this study was to measure and map scapula osseous thickness to identify the optimal areas for internal fixation. Eighteen (9 pairs) scapulae from 2 female and 7 male cadavers were used. After harvest and removal of all soft tissues, standardized measurement lines were made based on anatomic landmarks. For consistency among scapulae, measurements were taken at standard percentage intervals along each line approximating the distance between two consecutive reconstruction plate screw holes. Two-mm-diameter drill holes were made at each point, and a standard depth gauge was used to measure thickness. The glenoid fossa (25 mm) displayed the greatest mean osseous thickness, followed by the lateral scapular border (9.7 mm), the scapula spine (8.3 mm), and the central portion of the body of the scapula (3.0 mm). To optimize screw purchase and internal fixation strength, the lateral border, the lateral aspect of the base of the scapula spine, and the scapula spine itself should be used for anatomic sites of internal fixation of scapula fractures.

Suprascapular Nerve Reconstruction in 118 Cases of Adult Posttraumatic Brachial Plexus

BACKGROUND

Shoulder stabilization is of utmost importance in upper extremity reanimation following paralysis from devastating brachial plexus injuries. The purpose of this report is to present the authors' experience with suprascapular nerve reconstruction in 118 cases of adult brachial plexus lesions. Outcomes were analyzed in relation to various factors, including patient age, denervation time, donor nerve used, and functional restoration achieved in the supraspinatus versus the infraspinatus muscles.

METHODS

The medical records of 118 adult patients operated on by a single surgeon between 1978 and 2002 who had suprascapular nerve reconstruction were reviewed; 102 patients had adequate follow-up. Direct neurotization of the suprascapular nerve was carried out in 78 patients, while in 40 patients, interposition nerve grafts were used. In 80 patients, the distal spinal accessory was used as the motor donor nerve for suprascapular nerve neurotization, while in 10 patients, other extraplexus motor donors were used. In 28 patients, intraplexus motor donors were used to reinnervate the suprascapular nerve.

RESULTS

Results were good or excellent in 79 percent of the patients for the supraspinatus muscle and in 55 percent for the infraspinatus. There was a statistically significant difference between direct spinal accessory to suprascapular nerve neurotization and accessory to suprascapular via a nerve graft. Early surgery and less than 6 months of denervation time yielded significantly better results than late surgery and more than 6 months of delay in the treatment.

CONCLUSIONS

Suprascapular nerve neurotization is a high priority in upper limb reanimation for restoration of glenohumeral joint stability, shoulder abduction, and external rotation. Concomitant neurotization of the axillary nerve yields improved outcomes in shoulder abduction function. The best results are seen when direct neurotization of the suprascapular nerve is performed within 6 months from the injury.

Reliability of palpation of humeral head position in asymptomatic shoulders

The purpose of this study was to determine if, within a normal population: (1) palpation of the humeral head, relative to the acromion, in three static positions, was a reliable technique (2) there was a difference in humeral head position between the dominant and non-dominant shoulders in the three positions (3) there was a difference in humeral head position relative to the acromion between the arm at side (AS), the 90 degrees abduction/external rotation (AER) and 90 degrees abduction/internal rotation (AIR) positions. This test-retest study recorded palpation landmarks using a standardized protocol. Intra-tester reliability was above 0.8 for both AS and AER and all other ICCs were below 0.6. There was no systematic difference between dominant and non-dominant sides in any of the three positions (AS P=0.408, AER P=0.448, AIR P=0.233). There was a significant difference in measurements between each position (P<0.001). It can be concluded that, palpation of humeral head position in relation to the acromion is a reliable technique in the AS position. These normative data provide a baseline that can be used for future comparison if differences are found to exist in subgroups with pathological shoulder conditions where larger glenohumeral translations are thought to exist.

The glenoid center line

This study sought to define a point on the anterior glenoid surface to serve as a marker for glenoid orientation and to present the concept of a glenoacromial version angle. Twenty fresh-frozen cadaver scapulas were examined. A line perpendicular to the glenoid surface exited the anterior scapular cortex in all specimens at an average distance of 29.3 +/- 3.9 mm. The average glenoacromial version angle was 60 degrees +/- 110 degrees. These numbers may allow better intraoperative assessment of glenoid version.

Quantitative morphology of the scapula: normal variation of the superomedial scapular angle, and superior and inferior pole thickness

This study examined the normal variation of the superomedial scapular angle and the thickness of the superior and inferior scapular borders. Scapulae of 53 cadaver shoulders were dissected free from all soft tissue. A line was drawn from the most superior to the most inferior point on each scapula, and the scapulae were cut along this line to obtain cross sections. The supero-medial scapular angle (alpha) was measured with a goniometer from the cross section as a ABC: through the inferior tip (A), base of the spine (B), and superior tip (C). Superior and inferior pole thickness was measured with a digital caliper from the thickest portions on the cross section of the poles. Average superomedial angle was 139 degrees +/- 6 degrees (range: 125 degrees - 156 degrees). Average thickness for the superior and inferior poles was 3.9 +/- 0.9 mm (range: 2.1 - 8.3 mm) and 7.5 +/- 1.5 mm (range: 4 - 11 mm), respectively. The thickness of both superior and inferior poles was significantly different between male and female specimens (P < .05), with male scapulae having the higher values.

The painful scapulothoracic articulation: surgical management

To clarify the indications and effectiveness of surgical decompression for scapulothoracic bursitis, 16 patients were evaluated, who during a 5-year period, had surgical treatment of refractory pain and snapping in the scapulothoracic region. Twelve women and four men with a mean age of 41 years had one of five methods of surgical decompression of the scapulothoracic articulation. Six patients had an open resection of the scapulothoracic bursa with excision of the superomedial portion of the scapula, two had this procedure using an arthroscopic method, and six had a combined approach with arthroscopic scapulothoracic bursectomy and open resection of the superomedial scapula through a small incision. One patient had an arthroscopic and one an open scapulothoracic bursectomy only. At final followup of an average of 36 months (range, 24-69 months), 81% of patients reported satisfaction with the procedure and indicated they would have it again based on the relief they obtained from pain. The Simple Shoulder Test was 9.8 (range, 2-12). Although there was no statistical difference in the success using any given technique, we thought that the combined open and arthroscopic approach was the most effective, and surgical treatment is an acceptable method for treatment of refractory painful scapulothoracic bursitis.

Variations in glenoid rim anatomy: implications regarding anchor insertion

PURPOSE

The purpose of this study was to investigate normal bony anatomy of the glenoid rim and to define the angles for successful anchor placement for anterior and posterior labral repairs.

TYPE OF STUDY

An anatomic study using cadaveric shoulder specimens.

METHODS

Soft tissue was dissected from 20 cadaveric shoulders, and the glenoids were isolated. The glenoid specimens were scanned to obtain cross-sectional images using peripheral quantitative computed tomography (pQCT) in 4 different planes. Glenoid rim angles were measured from the cross-sectional pQCT images of the glenoids at 5 positions: the 3-o'clock, 4:30-, 6-, 7:30-, and 9-o'clock positions. Glenoid morphology was noted for each position.

RESULTS

The glenoid rim angles from the 3-o'clock to the 9-o'clock positions were 53 degrees +/- 5 degrees, 45 degrees +/- 7 degrees, 80 degrees +/- 10 degrees, 61 degrees +/- 10 degrees, 49 degrees +/- 4 degrees, respectively. Asymmetric morphology of the glenoid was noted with an almost straight line extending medially from the rim at the 3-o'clock position, whereas a concave morphology was noted at the 9-o'clock position. Similarly at the 4:30-o'clock position, the scapular bony surface did not curve toward the base as markedly as it did at the corresponding posterior 7:30-o'clock position.

CONCLUSIONS

The available bone mass for the anchor insertion was found to vary depending on the position of the glenoid rim. Both rim angle and glenoid morphology for each position must be considered when selecting the ideal anchor insertion angle for labral repair.

Anatomy of the superior glenoid rim. Repair of superior labral anterior to posterior tears

BACKGROUND

Successful placement of a fixation device on the superior glenoid rim during superior labrum repairs requires accurate knowledge of the glenoid rim anatomy.

PURPOSE

To investigate the normal bony anatomy of the superior glenoid rim.

STUDY DESIGN

Descriptive anatomic study.

METHODS

Twenty cadaveric glenoid specimens were scanned to obtain cross-sectional images with peripheral quantitative computed tomography in three different positions, each perpendicular to the articular surface. Two straight lines were drawn along the interior bony margins of the articular surface and cortex, and image analysis software was used to calculate the angle between these lines. Three bony angles were measured.

RESULTS

The bony angles from the 10:30-, 12-, and 1:30-o'clock cross-sections were 55 degrees +/- 5 degrees, 64 degrees +/- 5 degrees, and 62 degrees +/- 8 degrees, respectively. The posterosuperior angle (at the 10:30-o'clock position) was statistically significantly lower than the superior and anterosuperior angles. Intraobserver variation was less than 3%.

CONCLUSIONS

The most superior point of the glenoid rim (12-o'clock position) seems to provide the most bone stock for anchor insertion. The available bone support was found to decrease posteriorly on the glenoid rim.

CLINICAL RELEVANCE

During superior labral repairs, the anchor or fixation device should be inserted at approximately a 30 degrees angle in relation to the articular surface for maximal bone support.

Magnetic resonance imaging of the shoulder: rotator cuff

Magnetic resonance imaging has proven to be useful in the assessment of rotator cuff injuries. Improvements in magnetic resonance techniques, including fast spin-echo imaging and fat saturation, have facilitated demonstration of tendinous abnormalities of the rotator cuff. Rotator cuff disease is multifactorial. Primary impingement within the coracoacromial arch, degeneration of the rotator cuff tendons, trauma, and glenohumeral instability may be contributing factors. Shoulder pain in athletes can be related to acute myotendinous and muscle injuries, which can be easily detected using magnetic resonance imaging.