Safe zone for arthroscopic resection of the superomedial scapular border in the treatment of snapping scapula syndrome

Arthroscopic resection of the superomedial corner of the scapula was performed in 20 fresh frozen cadaveric specimens to define clinically safe and useful margins for arthroscopic bony resection. The lateral border of resection was delineated by directing the burr either toward a specifically chosen arthroscopic resection target (ART) situated equidistant between the inferior scapular angle and scapular spine or more lateral to the inferior angle of the scapula. The minimum distances between the suprascapular notch and the lateral edge of the resection were 25 mm (average, 31 mm) in the ART group and 10 mm (average, 21 mm) in the inferior angle group (P < .01). From the results of our study, we recommend a safe zone for arthroscopic removal of bone and soft tissue from the superomedial corner of the scapula. The medial border is defined by the medial scapula and scapular spine; the lateral border is drawn between Bell's portal and the ART.     

Congruency of scapula locking plates: implications for implant design

We conducted a study to evaluate the congruency of fit of current scapular plate designs. Three-dimensional image-processing and -analysis software, and computed tomography scans of 12 cadaveric scapulae were used to generate 3 measurements: mean distance from plate to bone, maximum distance, and percentage of plate surface within 2 mm of bone. These measurements were used to quantify congruency. The scapular spine plate had the most congruent fit in all 3 measured variables. The lateral border and glenoid plates performed statistically as well as the scapular spine plate in at least 1 of the measured variables. The medial border plate had the least optimal measurements in all 3 variables. With locking-plate technology used in a wide variety of anatomical locations, the locking scapula plate system can allow for a fixed-angle construct in this region. Our study results showed that the scapular spine, glenoid, and lateral border plates are adequate in terms of congruency. However, design improvements may be necessary for the medial border plate. In addition, we describe a novel method for quantifying hardware congruency, a method that can be applied to any anatomical location.     

Osseous anatomy of the scapula

Detailed anatomy and morphometry of the scapula were obtained to provide information for surgical procedures such as hardware fixation, drill hole placement, arthroscopic portal placement, and prosthetic positioning. Twenty-six measurements were made in 15 pairs of scapulas from cadavers. The average length of the scapulas from the superior to the inferior angle was 155 +/- 16 mm (mean +/- standard deviation). The thickness of the medial border 1 cm from the edge was 4 +/- 1 mm. The superior border was sharp and thin, and the suprascapular notch was present as a foramen in two scapulas. The distance from the base of the suprascapular notch to the superior rim of the glenoid was 32 +/- 3 mm. The length of the spine from the medial edge of the scapula to the lateral edge of the acromion was 134 +/- 12 mm. The anteroposterior width of the spine at 1 and 4 cm from the medial edge was 7 +/- 1 and 18 +/- 3 mm, respectively; the width at the lateral edge (spinoglenoid notch) was 46 +/- 6 mm. The acromion measured 48 +/- 5 mm x 22 +/- 4 mm and was 9 +/- 1 mm thick. The acromial shape was flat in 23%, curved in 63%, and hooked in 14% of scapulas. The distance from the glenoid to the acromion was 16 +/- 2 mm. The glenoid dimensions were 29 +/- 3 mm (anteroposterior) x 36 +/- 4 mm (superoinferior) and faced posterior by 8 +/- 4 degrees. Anteroposterior thickness of the head of the scapula 1 cm from the surface was 22 +/- 4 mm. The thickness of the coracoid was 11 +/- 1 mm. The average length of the coracoacromial ligament was 27 +/- 5 mm. Scapulas from male cadavers were significantly larger than scapulas from female cadavers in 19 measurements.     

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.     

Successful treatment of fractures of the base of the acromion after reverse shoulder arthroplasty: Case report and review of the literature

Fractures of the acromion and scapula are known to occur after reverse shoulder arthroplasty. We present a case of a fracture at the base of the acromion 5 months after arthroplasty treated successfully with dual plating of the acromion. Eighteen months after fracture fixation, the patient had 160 degrees of active forward flexion, a QuickDASH of 29.5, a Constant score of 69 and she was satisfied with the result. A concomitant review of the literature produced, in addition to our patient, 56 cases. These were used to produce a classification system, based on bony and functional anatomy as follows. Tip fractures are of the most lateral or anterior portion of the acromion, those of the body of the acromion are medial to the tip but lateral to the beginning of the scapular base. Fractures at the scapular base are termed fractures of the base of the acromion and those more medial to that, fractures of the scapular spine. The functional results of these case series demonstrated poorer functional outcomes for more medial fractures. As future research in this domain increases, clarity on the nomenclature of these fractures will allow for prognostication and treatment based on fracture location as well as comparison between studies.     

The Sprengel deformity. Morphometric analysis using 3D-CT and its clinical relevance

We evaluated scapular dysplasia and malposition in 15 patients with the Sprengel deformity using three-dimensional CT (3D-CT). The shape, height-to-width ratio, the areas of both scapulae, the anterior curvature of the supraspinous portion and glenoid version were assessed on scapular posterior, medial and inferior views. The degree of rotation and superior displacement were measured on the trunk posterior view. The omovertebral connection was also assessed and correlated with the operative findings. Most of the affected scapulae had a characteristic shape with a decrease in the height-to-width ratio and were larger than the contralateral scapulae. There was an inverse relationship between scapular rotation and superior displacement. The typical curve of the supraspinous portion of the scapula was seen in only three cases. There was no significant difference in glenoid version. The point of tethering of the omovertebral connection may determine the shape, rotation and superior displacement of the scapula. 3D-CT was helpful in delineating the deformity in detail, and in planning scapuloplasty.     

The subscapular and subcoracoid bursae: descriptive and functional anatomy

The subscapularis and subcoracoid bursae, as well as the subscapularis muscle, were studied in 42 fresh cadaveric shoulders. Fibrous bands were found in the medial part of the muscle; they were intercalated with the distal tendon-like bands. The superior distal fibrous band was always found to be thicker than the others. Strong fibrous attachments of the subscapularis muscle were found along the lateral border of the scapula as well as along the medial third of the bony crests in the subscapular fossa. Between the crests, the muscle bundles were directly attached to the bone. In the lateral part of the scapula, the subscapularis muscle had only weak connective links with the bone. The subscapularis bursa was found in all cases as a pouch strongly attached to the scapular neck and the adjacent part of the joint capsule. The top of the bursa was linked to the coracoid process by a fibrous attachment called the suspensory ligament. The subcoracoid bursa had only weak connective links with the coracoid process. In 28% of cases, the subscapularis and subcoracoid bursae merged into a unique wide bursa. The subscapular bursa had two types of links with the muscle: (1). weak connective links with the superficial muscle bundles and (2). at least 2 fibrous arcs joining the lateral tendon-like bands, the bursa, and bony crests of the subscapularis fossa. These arcs allow the bursa to follow the course of the muscle exactly. During movements of the glenohumeral joint, the subscapularis muscle sustains huge changes of orientation, particularly the upper part of the muscle that coils around the coracoid process. The strong superior fibrous band enables the muscle to maintain contact with the coracoid process. It is the function of the subscapularis and subcoracoid bursae to manage the friction of the superficial fibers against the scapular neck, the humeral head, and the coracoid process.     

Use of the scapular spine in lumbar fusion procedures: cadaveric feasibility study. Laboratory investigation

OBJECT: Graft sources for lumbar fusion include synthetic materials, donor grafts, and autologous bone such as the iliac crest. Considering the data indicating that autologous bone grafts generate the best results for fusion, the next logical step is to seek alternative donor sites in an attempt to reduce the complications associated with these procedures. To the authors' knowledge, autologous scapula has not been explored as a potential source for posterior lumbar fusion graft material. Therefore, the following study was performed to verify the utility of this bone in these procedures. METHODS: Six adult cadavers (mean age 71 years), four formalin-fixed and two fresh specimens, were used in this study. With the cadaver in the prone position, an incision was made over the spine of the scapula. Soft tissues were stripped from the middle of this region of the scapula, and bone segments were removed with a bone saw and used for a posterior lumbar fusion procedure. RESULTS: A mean length of 11.5 cm was measured for the spine of the scapula and the mean thicknesses of this bone at its medial part, segment just medial to the spinoglenoid notch, and acromion were 1 cm, 2.2 cm, and 2.5 cm, respectively. No obvious injury to surrounding vessels or nerves was found using this procedure, and adequate fusion was achieved with it. CONCLUSIONS: Following clinical testing, such a bone substitute as autologous scapular spine might be a reasonable alternative to iliac crest grafts for use in posterior lumbar fusion procedures.     

Study on the movement of the scapula during elevation of the arm

To clarify the shoulder movement, changes of the tilting angle of the scapula were elevated radiographically in three dimensions during arm elevation. Utilizing data of the tilt of the glenoid fossa against the plane of scapula measured in dry bones, the direction of the glenoid fossa during arm elevation in living subjects was evaluated. The medial tilting angle was nearly constant at about 40 degrees from the resting position to an elevation of the arm to 150 degrees position. The average downward tilt was 12.46 degrees in the resting position; thereafter it gradually tilted backward. Horizontal tilt of the glenoid fossa following arm elevation was 46.15 degrees in the resting position, 46.15 degrees at 90 degrees of elevation, 38.79 degrees at 150 degrees of elevation, and 33.0 degrees at maximum elevation. These findings suggest that the "scapular plane" is the plane 40 degrees against the frontal plane in the range from 0 degrees to 150 degrees elevation of the arm, and that "zero position" is at 150 degrees elevation position in the scapular plane.     

Thinking outside the glenohumeral box: Hierarchical shape variation of the periarticular anatomy of the scapula using statistical shape modeling

Variation in the shape of the glenoid and periarticular anatomy of the scapula has been associated with shoulder pathology. The goal of this study was to identify the modes of shape variation of periarticular scapular anatomy in relation to the glenoid in nonpathologic shoulders. Computed tomography scans of 31 cadaveric scapulae, verified to be free of pathology, were three-dimensionally reconstructed. Statistical shape modeling and principal component analysis identified the modes of shape variation across the population. Corresponding linear and angular measurements quantified the morphometric variance identified by the modes. Linear measures were normalized to the radius of the inferior glenoid to account for differences in the scaling of the bones. Five modes captured 89.7% of total shape variation of the glenoid and periarticular anatomy. Apart from size differences (mode 1: 33.0%), acromial anatomy accounted for the largest variation (mode 2: 32.0%). Further modes described variation in glenoid inclination (mode 3: 11.8%), coracoid orientation and size (mode 4: 9.0%), and variation in coracoacromial (CA) morphology (mode 5: 3.1%). The average scapula had a mean acromial tilt of 49 ± 7°, scapular spine angle of 61 ± 6°, the glenoid inclination of 84 ± 4°, coracoid deviation angle of 26 ± 4°, coracoid length of 3.7 ± 0.3 glenoid radii, and a CA base length of 5.6 ± 0.5 radii. In this study, the identified shape modes explain almost all of the variance in scapular anatomy. The acromion exhibited the highest variance of all periarticular anatomic structures of the scapula in relation to the glenoid, which may play a role in many shoulder pathologies.     

The spinoglenoid ligament. Anatomy, morphology, and histological findings

BACKGROUND: Dysfunction of the distal branch of the suprascapular nerve has been reported in athletes involved in throwing or overhead sports. The consistent presence of a dynamic anatomic structure, the spinoglenoid ligament, overlying the nerve in the spinoglenoid notch may be a contributing factor to the dysfunction of this nerve. The purpose of this study was to report the anatomy, morphology, and histological characteristics of the spinoglenoid ligament. METHODS: The spinoglenoid ligaments of fifty-eight fresh-frozen cadaver shoulders were dissected to evaluate their anatomic dimensions, histological characteristics, and relationship to the suprascapular nerve, the posterior part of the capsule, and the glenoid rim. The spinoglenoid ligament was harvested, with its insertions on the scapular spine and on the capsule and glenoid left intact, for the histological analysis. RESULTS: Dissection revealed that a spinoglenoid ligament was present in all specimens. The ligament was found to form an irregular quadrangular shape. On gross examination, the deep fibers of the ligament extended from the lateral aspect of the scapular spine to the posterior part of the glenoid and the superficial fibers blended with the posterior aspect of the shoulder capsule. Histological sections demonstrated Sharpey fibers inserting into bone at the scapular spine and blending with the posterior aspect of the shoulder capsule to insert into the posterior surface of the glenoid, findings that confirmed the ligamentous nature of this structure. CONCLUSIONS: This study revealed the presence of the spinoglenoid ligament in all of the shoulders that were examined, with some variation in the size of the ligament.     

Scapular allografts. A report of two cases.

Some malignant tumors of the scapula can be adequately treated by limb-sparing, partial, or total scapulectomy. However, resection of the glenoid portion of the scapula and total scapulectomy result in an unsightly shoulder. In an attempt to minimize the functional impairment and restore stability and cosmesis, scapular glenoid allografts offer a reasonably good biologic replacement. This report describes the cases of a 45-year-old woman and a 32-year-old man in whom massive osteoarticular allografts were used. In one patient, good stability, cosmesis, and function were restored after resection of the glenoid portion. In the other patient, shoulder stability, cosmesis, and limited function were restored after total scapulectomy. No reports of scapular allografts seem to have been previously published in the literature.     

Fractures of the anatomical neck of the scapula: two cases and review of the literature

Anatomical neck fractures of the scapula are rare. The authors have found in the literature only four radiologically documented fractures of the anatomical neck of the scapula. Two of them were published by Hardegger et al., the third case was published by Arts and Louette. The last case, in fact only a radiograph and a rather poor 3D CT reconstruction of a fracture of the anatomical neck of scapula, was published by Jeong and Zuckerman. Together with author’s two patients, the group of radiologically verified anatomical neck fractures of the scapula comprises six cases in total (four men, one woman, one gender unspecified). Analysis of the radiographs showed that in all these cases, the fracture line separated only the glenoid fossa from the scapular body, with a short spike of the lateral border of the scapula. The proximal part of the vertical fracture line ran into the coracoglenoid notch, between the upper border of the glenoid and the base of the coracoid process. The distal part of the fracture line crossed the lateral border of the scapular body 2–4 cm distal to the inferior pole of the glenoid fossa. The gleniod fragment was always formed by the glenoid fossa and a short spike of the lateral border of the scapular body. In five cases, the glenoid fragment, together with the humeral head, was displaced distally and the humeral head came to lie below the level of the coracoid process. At the same time, the glenoid fragment rotated into a valgus position. Only in one case, did the radiographs fail to show valgus displacement and the fracture was angulated in the transverse plane. In all six cases, the subacromial space between the acromion and the humeral head was widened. All fractures were operated on via a Judet posterior approach. In five cases, the outcome of the operation was assessed at 3, 5, 12, 21 and 120 months after surgery, three-being rated as excellent or very good, one as good and one as poor.     

Is radiograph glenopolar angle accurate for extraarticular scapular neck fractures?

BackgroundPlain radiographs still play a role in management of extraarticular scapular neck fractures. Glenopolar angle (GPA) is one of the radiograph measurements that is used to determine the necessity for surgery. Our aim was to establish reliability of GPA on plain radiograph in patients with extraarticular scapular neck fractures.MethodsWe performed a multicentre retrospective study including all patients with extraarticular scapular neck fractures with available imaging between 2006 and 2012. We excluded intra-articular glenoid fractures, scapular blade fractures, acromion fractures, and scapular spine fractures. We compared GPA on plain radiograph with three dimensional computed tomography (3D CT) measurement, as well as contribution of radiograph rotational error, glenoid inclination, and medial shortening of glenoid fragment towards GPA measurement.ResultsOne hundred patients met the inclusion criteria. The mean difference between the GPA measurements on radiographs and 3D CT was 6.1 ± 0.85° (95% confidence interval) as an absolute value. In terms of contribution to GPA values, GPA changed by one degree with ten degrees of radiograph rotational error, three degrees of glenoid inclination, and three millimetres of glenoid fragment medial shortening.ConclusionPlain radiograph can provide a clinician with a reasonable estimation of the GPA. Glenoid inclination has a greater influence on GPA compared to medial shortening.     

An anatomical study of the suprascapular nerve

The course of the suprascapular nerve and its distance from fixed scapular landmarks were measured in 90 cadaveric shoulders. In an additional 15 cadavers, three pins were passed at various angles in a general anterior-posterior direction through the middle of the glenoid neck just inferior and lateral to the base of the coracoid process. The distance between the exit site on the posterior glenoid neck and the suprascapular nerve at the base of the scapular spine was recorded for each pin. Inferiorly directed pins were the furthest from the suprascapular nerve and averaged 16 mm. On the basis of these data, a relative safe zone is described in the posterior glenoid neck. Knowledge of the anatomic course of the suprascapular nerve may aid the physician in the diagnosis and treatment of suprascapular neuropathies. Appreciation of the safe zone may help the shoulder surgeon avoid iatrogenic injury to the suprascapular nerve during arthroscopic Bankart procedures and other open surgical procedures requiring dissection of the posterior glenoid neck.     

Facial reconstruction using a combined flap of the subscapular axis simultaneously including separate medial and lateral scapular vascularized bone grafts

With the better understanding of the blood supply to the scapula, combined flaps of the lateral scapula along with the latissimus dorsi and/or serratus anterior are well known. The medial border of the scapula, in this respect, has been underused. The authors present a case report in which a conjoined combined free flap consisting of four free tissue transfers based on the subscapular axis was used in simultaneous reconstruction of a gunshot wound to the face. This included a medial scapular osteofasciocutaneous flap for the mandible, a lateral scapular osseous flap for the anterior maxilla, a serratus anterior muscle flap for the cheek, and a separate latissimus dorsi musculocutaneous flap for the forehead. This flap was successful and provides another alternative to the resolution of complex problems needing multiple areas of both soft-tissue coverage and vascularized bone graft.     

Statistical shape modeling-based reconstruction eliminates the need for full scapular computed tomography scan data in preoperative total shoulder arthroplasty planning

BackgroundPreoperative total shoulder arthroplasty (TSA) planning tools use a three-dimensional (3D) model of the full scapula based on computed tomography (CT) images with a scan length covering the complete scapula with a given radiation exposure for patients. The aim of this study is to investigate whether full scapular models can be reconstructed from partial CT data.MethodsIn this retrospective cohort study, bone models representing 5 scan lengths with decreasing levels of scapular coverage (level 1-5) were created. All the models were reconstructed with a validated statistical shape model (SSM) allowing automatic 3D measurements of glenoid version, inclination, scapular offset, and center point position. Radiation exposure between 2 patient groups (group 1 = corresponding to L1, group 2 = complete scapula) was compared.ResultsIn terms of inclination and version, we found a mean absolute difference between the complete model and the different partial scan models of 0.5° (SD 0.4°). The maximum difference was 3° for inclination and 2° for version. For scapular offset and center point position, the mean difference was 0 mm (max 1 mm). The mean radiation exposure was 4 mSv (SD 2 mSv) for group 1 and 13 mSv (SD 6 mSv) for group 2 (P = .009).ConclusionAn SSM-based reconstruction technique can accurately reconstruct complete scapular bone models based on partial CT scan data. Incorporation of an SSM-based reconstruction technique in software tools for preoperative TSA planning would lead to decreased radiation exposure (9 mSv) for patients without influencing its accuracy.     

CT-based preoperative analysis of scapula morphology and glenohumeral joint geometry.

OBJECTIVE: To investigate the geometry of the glenohumeral joint using three-dimensional (3D) models; define landmarks, planes, angles and regions of interest; and analyze the exact morphology of the scapula. MATERIALS AND METHODS: We reconstructed 3D scapula models based on computed tomography (CT) data sets of 12 healthy controls. Three-dimensional models were reconstructed using the 3D Slicer2 (Surgical Planning Lab, Boston, MA), which provides interactive measurement. The 3D model and measuring tools can be freely shifted and rotated in all planes. RESULTS: The average length of the scapulas was 209.58 +/- 26.72 mm (left) and 223.68 +/- 47.74 mm (right); width was 124.03 +/- 13.28 mm (left) and 141.44 +/- 27.78 mm (right); and volume was 121.38 +/- 12.02 ml (left) and 130.24 +/- 20.86 ml (right). The glenoid dimensions were 34.34 +/- 5.62 mm (left) and 36.44 +/- 7.36 mm (right) (anteroposterior); and 49.16 +/- 7.68 mm (left), 51.46 +/- 10.07 mm (right) (superoinferior). For all average values, scapulas from male controls were significantly larger than those from females, and right sides were larger than left sides (p < 0.05). The glenoid version was nearly the same for male/female and left/right (left = 9.02 +/- 3.89 degrees retroversion; right = 8.26 +/- 3.72 degrees retroversion) (p > or = 0.05). CONCLUSION: The 3D measurement of scapula morphology compared with geometry of the glenohumeral joint leads to a more precise planning of shoulder surgery. As new shoulder prostheses are intended to reconstruct the normal anatomy as closely as possible, such exact 3D measurements may be used for optimization.     

Three-dimensional rotation of the scapula during functional movements: an in vivo study in healthy volunteers

The goal of this study was to measure 3-dimensional shoulder motion by use of a direct invasive technique during 4 different arm movements in healthy volunteers. Eight subjects with healthy shoulders were recruited. Optoelectronic marker carriers (ie, infrared light-emitting diodes) were mounted on bone pins, which were inserted into the lateral scapular spine. Subjects performed 4 different arm movements while the motion was being recorded by a precision optoelectronic camera. Joint angles were calculated in 3 dimensions. Intraclass correlation coefficients and root-mean-square differences were calculated as measures of reliability. During abduction, the scapula tipped posteriorly (44 degrees +/- 11 degrees), rotated upward (49 degrees +/- 7 degrees), and rotated externally (27 degrees +/- 11 degrees). For reaching, the scapula consistently rotated upward (17 degrees +/- 3 degrees) and rotated internally (18 degrees +/- 6 degrees) whereas tipping was generally less than 10 degrees (5 degrees +/- 2 degrees). Overall, the range of scapular movement for the hand behind the back was small and variable, with most rotations not exceeding 15 degrees. For horizontal adduction, the scapula tipped anteriorly (8 degrees +/- 3 degrees), rotated upward (5 degrees +/- 2 degrees), and rotated internally (27 degrees +/- 6 degrees). These scapular rotations provide normative data that will be useful for diagnosing scapular dysfunction.     

Reverse total shoulder arthroplasty: radiological and clinical result using an eccentric glenosphere

In reverse shoulder arthroplasty, an eccentric glenosphere has been developed with the aim of lowering the centre of rotation, in order to prevent inferior scapular notching as occurs with concentric designs. The objective of this retrospective study was to evaluate clinical and radiographic outcomes using the eccentric glenosphere and to determine whether this design might prevent inferior scapular notching. Between 2006 and 2010, 40 patients affected by cuff tear arthropathy underwent reverse shoulder arthroplasty with an eccentric 36-mm glenoid component. Patients with less than 2 years' follow-up were excluded. The results for 25 patients with a minimum of 24 months' follow-up are reported. Clinical and radiographic evaluation was performed preoperatively and at 1, 3, 6 months, 1 year and annually thereafter. All patients were evaluated with MRI or CT scan preoperatively and with X-ray examinations postoperatively to evaluate the presence of inferior scapular notching and to measure the prosthesis-scapular neck angle (PSNA), the peg-glenoid rim distance (PGRD) and the distance between the scapula neck and the glenosphere. At last follow-up (average 27.5 months, range 24-46), the Constant Score, the VAS score and range of motion had improved significantly. The average PSNA was 92° + 29°, the average PGRD was 21.2 mm + 9 mm and the average distance between the inferior bony glenoid rim and the inferior edge of the glenosphere was 4.3 mm + 0.8 mm. No inferior scapular notching and no implant-related complications were seen. The data suggest that use of an eccentric glenosphere lowers the centre of rotation, reducing the risk of inferior scapular notching. Level of evidence IV.