Anomalies of the scapula

Nonunion of the so-called acromion: a systematic review with consideration of the terminology

INTRODUCTION

There is no widely accepted standard for the classification and treatment of traumatic acromion/scapular spine fracture nonunion due to the scarcity of this condition and the confusion of terminology.

MATERIALS AND METHODS

PubMed and Scopus were searched using "scapular fracture" and "acromion fracture" or "scapular spine fracture" as search terms. The inclusion criteria were English full-text articles concerning acromion/scapular spine fracture nonunion that described patient characteristics and presented appropriate images. The exclusion criteria were cases without appropriate images. Citation tracking was conducted to find additional articles and notable full-text articles written in other languages. Fractures were classified using our newly proposed classification system.

RESULTS

Twenty-nine patients (19 men, 10 women) with 29 nonunions were identified. There were four type I, 15 type II, and 10 type III fracture nonunions. Only 11 fractures were isolated. The mean period from initial injury to final diagnosis was 35.2 ± 73.2 months (range 3-360 months) (n = 25). The most frequent cause of delayed diagnosis was conservative treatment for fracture in 11 patients, followed by oversight by the physician in 8. The most common reason for seeking medical advice was shoulder pain. Six patients received conservative therapy, and 23 received operative treatment. Fixation materials included various plates in 15 patients, and tension band wiring in 5. Bone grafting was performed in 16 patients (73%, 16/22). Of the 19 surgically treated patients with adequate follow-up, the outcome was rated excellent in 79%.

CONCLUSIONS

Isolated acromion/scapular spine fracture nonunion is rare. Fracture type II and III, arising in the anatomical scapular spine, accounted for 86% of the fractures. Computed tomography is required to prevent fracture oversight. Surgical therapy produces good stable results. However, it is important to select the appropriate surgical fixation method and material after considering the anatomical characteristics of the fracture and stress on the fractured portion.

LEVEL OF EVIDENCE

V.

A review of the coracoclavicular joint: Description, etiology, and clinical significance

The coracoclavicular joint (CCJ) is a synovial joint that forms between the conoid tubercle of the clavicle and the coracoid process of the scapula in approximately 2.5% of the population. The number of bilateral to unilateral cases is almost equal. The number of right-sided and left-sided cases is also almost equal. It is found in both males and females but most often in male adults. Very few cases have been identified in juveniles. Found in populations all over the world, the highest frequencies of CCJ are in Asia. The etiology is unknown but it is most likely caused by metaplastic change of the trapezoid and surrounding tissue due to compression and friction of the coracoacromial ligament between the clavicle and coracoid process. Typically asymptomatic, but if so, the most common complaint is anterior should pain exacerbated by extreme abduction. Successful treatment includes steroid injection and surgical excision.

Surgical treatment of a symptomatic os acromiale by arthroscopy-assisted double-button fixation: a case report

CASE

We present the case of a symptomatic os acromiale in a 51-year-old female patient. Arthroscopy-assisted treatment was performed using a double-button fixation system and additional suture cerclage. The patient presented with complete radiographic bone union, pain relief, improved range of motion and did not require hardware removal at the 12-month follow-up.

CONCLUSION

The achievement of persistent consolidation between the two fragmented bone surfaces, without further need for hardware removal and improved clinical outcome, suggests that our minimally invasive technique is appropriate for this specific indication. To our knowledge, this technique has not been described in the literature yet.

Coracoclavicular bursal changes on MRI: a diagnostic consideration in patients with shoulder pain and reduced coracoclavicular distance

OBJECTIVE

To describe MRI changes of the coracoclavicular bursa in patients presenting with shoulder pain and examine whether there is an association with coracoclavicular distance measurements.

METHODS

Retrospective analysis of 198 shoulder 3T MRI scans for patients with shoulder pain was performed. Two musculoskeletal trained radiologists read all MRI scans. Inter-reader and intra-reader agreements for the bursal changes were assessed using the Kappa coefficient. The coracoclavicular distance was stratified into three intervals: < 5 mm, 5-10 mm, and > 10 mm. Statistical analysis for the coracoclavicular bursal changes and coracoclavicular distance was conducted using Fisher's exact test.

RESULTS

Coracoclavicular bursal changes were detected in 9% (n = 18/198) of patients. There was a statistically significant association between coracoclavicular distance (< 5 mm) and the presence of coracoclavicular bursal changes (p-value = 0.011). All patients (100%, n = 18/18) with coracoclavicular bursal fluid presented with shoulder pain with 44.5% of the patients (n = 8/18) describing anterior shoulder pain. A statistically significant association was detected between coracoclavicular bursal changes and anterior shoulder pain (p-value = 0.0011). Kappa coefficient for the bursal changes inter-reader agreement was moderate (0.67) and the intra-reader agreement was almost perfect (0.91).

CONCLUSION

Coracoclavicular bursal changes were detected in 9% of shoulder MRI scans and were associated with reduced coracoclavicular distance (< 5 mm) suggesting an underlying mechanical disorder such as a friction or an impingement process. Documenting coracoclavicular bursal changes in the MRI report could help address patients' concerns and guide further management particularly in the context of shoulder pain and coracoclavicular distance of less than 5 mm.

Acromial fractures following reverse shoulder arthroplasty: the role of the acromial morphology and a comparison of clinical outcomes

BACKGROUND

The purpose was to evaluate the relationship between acromial morphology and the location of acromial fractures following reverse shoulder arthroplasty and determine whether fracture location and displacement impact clinical outcomes.

METHODS

We performed a multicenter retrospective review of reverse shoulder arthroplasties complicated by acromial fractures. Radiographs were compared to determine the differences in acromial morphology, as well as fracture orientation and pattern, between patients with Levy type I (n = 17) and Levy type II (n = 25) fractures. Patients with a minimum of 2 years' follow-up were selected to examine the association between clinical outcomes and fracture location and displacement. Twenty-two patients were stratified based on whether they achieved the minimal clinically important difference (MCID) in the American Shoulder and Elbow Surgeons score (20 points). The groups were then compared regarding fracture location and displacement using measurements such as the acromiohumeral distance.

RESULTS

The Levy type I group had a higher acromial slope than the Levy type II group (127° vs. 117°, P < .001). Levy type I fractures had a transverse pattern occurring in the coronal plane, whereas Levy type II fractures had an oblique pattern occurring in the sagittal plane (P < .001). At final follow-up, 12 of 22 patients (55%) achieved the MCID. Those who did not achieve the MCID had more displaced fractures including a lower acromiohumeral distance (8 mm vs. 20 mm, P = .007). There was no difference in the distribution of Levy type I and type II fractures based on the MCID cutoff (P = .093).

CONCLUSION

An increased acromial slope is associated with transverse fractures in the Levy I region, whereas a lower acromial slope is associated with oblique fractures in the Levy II region. Overall, 55% of patients achieved the MCID at mid-term follow-up. The outcomes of those who did not achieve the MCID became worse postoperatively, and this was associated with increased fracture displacement.

Os acromiale: prevalence and associated patient-related factors-a population-based study of three thousand and fifty participants

Purpose

The presence of os acromiale is of clinical relevance before performing shoulder surgery but ethnic differences and little information regarding associated factors seem to be present. Population-based studies to clarify these topics are essential so the purpose of this study was to assess the prevalence, anatomy, and associations of os acromiale in a general adult population.

Methods

Both shoulders of 3050 participants from the population-based Study of Health in Pomerania (SHIP) were assessed on magnetic resonance imaging (MRI). Associations with the os acromiale were calculated for sex, age, body height, body weight, and heavy mechanical oscillations on the upper extremity.

Results

In total, 1.9% (58/3050) had an os acromiale, while 21 were unilateral left, 23 were unilateral right, and 14 were bilateral. Sixty-eight meso-acromions, three pre-acromions, and one meta-acromion were detected. Os acromiale were more frequent in men (right side: p = 0.037, left side: p = 0.005). Overall, no differences in sides (p = 0.808), to participants’ age (right: p = 0.993, left: p = 0.499), body height (right side: p = 0.241, left side: p = 0.154), and the exposure to heavy mechanical oscillations on the upper extremity (right: p = 0.054, left: p = 0.117) were detected.

Conclusion

Our results support the genetic theory for the aetiology of the os acromiale due to the lower prevalence of the os acromiale in north-eastern Germany compared to the worldwide prevalence (1.9 to 7%) and the lacking association to lifestyle, age, gender, or sides. Additionally, it is important to be aware of possible os acromiale before surgery.

Early to midterm outcomes of anatomic shoulder arthroplasty performed on dysplastic glenoids

BACKGROUND

Treatment of primary osteoarthritis with glenoid dysplasia or Walch type C glenoids remains controversial. There is scant literature available on patient outcomes after anatomic shoulder arthroplasty in patients with Walch type C glenoids. The purpose of this study was to evaluate the outcomes of total shoulder arthroplasty (TSA) for Walch type C dysplastic glenoids with standard (nonaugmented) glenoid components compared with TSA for glenoids with concentric wear and minimal erosion (Walch type A1). We hypothesized that TSA performed for Walch type C dysplastic glenoids with standard glenoid components can reliably produce successful results at short- to midterm follow-up.

METHODS

We identified all patients who had primary anatomic TSA performed for osteoarthritis in a prospective shoulder arthroplasty registry collected from 2004 to the present time. Twenty-nine patients met inclusion criteria of a preoperative Walch type C dysplastic glenoid, treatment with TSA using standard (nonaugmented) glenoid components, and a minimum of 2-year clinical follow-up. A matched cohort of 58 patients with a type A1 glenoid and minimum of 2-year clinical follow-up for anatomic shoulder arthroplasty served as the control group. The American Shoulder and Elbow Surgeons (ASES) score, the Single Assessment Numeric Evaluation (SANE), patient satisfaction, complications, and revisions were evaluated in both cohorts.

RESULTS

The mean follow-up for this study was 4.5 years (standard deviation, 2.6 years; range, 2-10 years). Baseline measures were not significantly different between the Walch type C dysplastic group and the matched type A1 cohort (all P > .05). Both groups showed significant improvements in ASES, ASES pain, and SANE scores from baseline to the final follow-up (all P < .001). The Walch type C group had no significant differences in ASES score (P = .118), ASES pain (P = .730), or SANE score (P = .168) compared with the matched type A1 cohort. The complication rate of patients with a type C glenoid was 14% (4 of 29) with a 7% (2 of 29) revision rate. Similarly, the complication rate for the A1 matched cohort was 17% (10 of 58) with a 12% (7 of 58) revision rate. Both groups had high patient satisfaction without statistical differences (P = .549). In addition, there were no differences in the rate of radiographic lucencies or Lazarus scores (P = .222).

CONCLUSIONS

Anatomic TSA reliably produced clinically significant improvements in pain and function and similar short- to midterm outcomes in patients with Walch type C dysplastic glenoids compared with patients with type A1 glenoids. Anatomic TSA with standard (nonaugmented) glenoid components should remain an option in patients with Walch type C dysplastic glenoids despite emerging treatment options including augmented glenoid components and reverse TSA.

Sprengel Deformity: Comprehensive Evaluation of Concomitant Spinal and Extraspinal Anomalies in 90 Patients

STUDY DESIGN

A retrospective, case series.

OBJECTIVE

The aim of this study is to evaluate the concomitant anomalies in patients with Sprengel deformity (SD).

SUMMARY OF BACKGROUND DATA

SD is the most common congenital anomaly of the shoulder. One or more associated anomalies may coexist in SD patients, similar to congenital scoliosis (CS); however, these anomalies and their relationship have not been studied in detail previously.

METHODS

SD patients who have applied to our institution between 2005 and 2019 were retrospectively reviewed. The patients were evaluated clinically and radiologically. The patients were divided in two groups as SD patients with CS and without CS, to analyze if these anomalies are present due to CS or SD. Physical examination findings, MRI, CT, and USG reports were analysed for accompanying pathologies. Patients with missing data were excluded. Student-t and Fisher's exact tests were used to compare the groups. Significance value was set as p = 0.05.

RESULTS

Ninety patients met inclusion criteria. The most common spinal anomaly was omovertebra, followed by spina bifida and Klippel-Feil. Tethered cord and diastematomiyelia were associated with CS (P = 0.0026 and P = 0.0057, respectively). The most common extra-skeletal anomaly was rib anomalies, followed by urinary and cardiac system anomalies. Rib anomalies were associated with CS (P = 0.00001).

CONCLUSION

Concomitant anomalies may accompany SD. The prognosis of SD may be affected by these anomalies. Therefore, patients should be evaluated for possible coexistent congenital anomalies.

LEVEL OF EVIDENCE

4.

Fractures of the Coracoid Process: Evaluation, Management, and Outcomes

Fractures of the coracoid process are relatively rare, and current management guidelines remain unclear. Most coracoid fractures occur in conjunction with other shoulder injuries, including dislocations and fractures. Identifying coracoid fractures can be difficult because most fractures are nondisplaced and can be missed on radiographs or may be masked by other injuries. Management is largely guided by fracture location and displacement. Conservative treatment is preferred for fractures that are minimally displaced, whereas indications for surgical fixation include fractures that are displaced (>1 cm), have progressed to a painful nonunion, or are associated with the disruption of the superior shoulder suspensory complex. Although conservative treatment has been historically favored, satisfactory outcomes have been reported for both surgical and nonsurgical treatment. We provide a comprehensive review of diagnosis and management strategies for coracoid fractures.

Os Acromiale: Reviews and Current Perspectives

Os acromiale is a developmental defect which results from the lack of an osseous union between the ossification centers of the acromion, leading to the fibrocartilaginous tissue connection. The prevalence of os acromiale is 1% to 15%, and is quite common in the African American population. Os acromiale in adults is easily diagnosed by symptoms and X-ray, particularly on the axillary view; however, the differential diagnosis of adolescents may require MRI or SPECT-CT. Generally, nonoperative therapy for symptomatic os acromiale should be started, including physiotherapy, nonsteroidal anti-inflammatory drugs, and injections. Surgical treatment is indicated after failed conservative treatment. In symptomatic patients with fixable acromiale, the tension band technique should be used to make the anterior aspect of the acromion elevated from the humerus head. In patients with small fragments which are unsuitable for reattachment, excision might be the best therapeutic option and lead to good outcomes. Whether using internal fixation or resection, the arthroscopic technique results in a better outcome and fewer complications, especially in older patients or athletes with overhead movement, because of the high incidence of shoulder impingement or rotator cuff tears which can be treated concurrently.

Management of symptomatic os acromiale: a survey of the American shoulder and elbow surgeons

BACKGROUND

The purpose of this paper was to survey members of the American Shoulder and Elbow Surgeons (ASES) to assess their opinion on management options, help highlight important clinical factors, and elucidate surgical preferences for the treatment of a symptomatic meso-os.

METHODS

An online questionnaire was distributed to the active members of the ASES. The survey queried surgeon demographics and perioperative management preferences, and presented multiple clinical case scenarios of patients with a presumed symptomatic, unstable os acromiale.

RESULTS

There were 116 ASES members who responded to the survey, and 26% (n = 30) who stated they do not operatively manage a symptomatic os. We identified two main clusters of respondents. Cluster 1 (n = 67) (as compared to cluster 2, n = 19) was comprised of surgeons with significantly more experience treating a symptomatic os acromiale (p < 0.05). These surgeons regarded gender, age, BMI, and hand dominance as important clinical factors when deciding when to proceed to surgery. Overall, arthroscopic management of the os was preferred, but those surgeons more experienced in treating os acromiale preferred open reduction and internal fixation (ORIF) in specific clinical cases.

CONCLUSION

The survey findings reflect the current lack of consensus in the treatment of a unstable, symptomatic os acromiale. Overall, arthroscopic management was preferred by most surgeons, though ORIF was preferred in certain clinical scenarios by those more experienced with os acromiale. The overall preference for arthroscopy suggests a possible shift in the treatment paradigm for patients with symptomatic meso-acromions, but higher level studies are needed to substantiate these findings.

Sprengel's deformity as congenital scapular asymmetry on bone scintigraphy

Bone scintigraphy is a valuable imaging modality for a diverse range of skeletal abnormalities. Incidental findings and congenital skeletal anomalies are not uncommonly encountered. Therefore, having a substantial knowledge of these findings, even rare ones, is essential for interpreting physicians. Here, we present a case of previously diagnosed malignancy referred for a bone scintigraphy for skeletal metastatic survey, in which Sprengel's deformity as congenital scapular asymmetry and cervicothoracic scoliosis was noted.

Symptomatic, Unstable Os Acromiale

Management of a persistently symptomatic, unstable os acromiale remains controversial. An unstable os acromiale is an easy diagnosis to miss and should be specifically evaluated for in patients with shoulder pain and a high degree of clinical suspicion. Surgical options include open or arthroscopic excision and open reduction and internal fixation. Open excision of large fragments has had poor results. Arthroscopic treatment is commonly used for small fragments (preacromion), and the technique has also been used in larger fragments (meso-os), but concerns persist over postoperative weakness secondary to shortening of the deltoid lever arm. Open reduction and internal fixation through a transacromial approach has been shown to have predictable union rates but can be complicated by symptomatic implant. Recent biomechanical studies have expanded our understanding of optimal fixation constructs, which may also decrease implant-related issues. Ultimately, the choice of which procedure to use will be dictated by patient factors such as age, activity level, and the nature of rotator cuff pathology. LEVEL OF EVIDENCE:: Level V.

Small but troublesome: accessory ossicles with clinical significance

Accessory ossicles are supernumerary and inconstant structures that are not caused by fractures. Derived from unfused ossification centers, accessory ossicles were first described by Vesalius in 1543. For centuries, they were believed to be asymptomatic. However, with advances in radiology techniques, many have been associated with painful syndromes. Although the original descriptions date from the sixteenth century, the subject is little discussed and, in some cases, controversial. The objective of this study was to describe the radiological aspects of a series of accessory ossicles and to review the evolution of their various descriptions, in order to revive discussion of the subject.

Bilateral Inferior Angle Ossicles of the Scapula: Pain Generators in a Young Woman: A Case Report

CASE

We present the case of a 16-year-old woman with refractory shoulder pain despite nonoperative treatment. The only shoulder pathology that was noted on advanced imaging was an unfused ossicle on the inferior angle of each scapula. She was successfully treated with simple excision bilaterally; as demonstrated by the shoulder scores, there was substantial improvement.

CONCLUSION

In young patients with vague and refractory shoulder pain with essentially normal radiographic findings, an ossicle on the inferior angle of the scapula may be considered a pain generator. Excision of the ossicle may provide excellent definitive treatment after more common shoulder pathology has been ruled out.

Arthroscopic excision of unstable os acromiale associated with impingement syndrome: a case report

Os acromiale is a rare anatomical variant that is caused by failure of fusion of the acromial apophysis and is usually asymptomatic. We report a case of impingement syndrome of the left shoulder secondary to unstable os acromiale, which was initially overlooked and confirmed only during arthroscopic examination. Arthroscopic excision of the unstable fragment was successful without residual dysfunction of the deltoid muscle.

Os acromiale fixation: a biomechanical comparison of polyethylene suture versus stainless steel wire tension band

BACKGROUND

Symptomatic hardware is a commonly reported complication after surgical fixation of an unstable meso-type os acromiale. This study compared the biomechanical properties of a cannulated screw tension band construct using a metal wire tension band vs. a suture tension band, considering that the suture construct could allow for decreased hardware burden in the clinical setting.

METHODS

A meso-type os acromiale was created in 16 cadaveric shoulders. Two cannulated 4-mm screws were placed in each specimen. Tension band augmentation was accomplished with a 1-mm stainless steel wire (wire group) or a #5 braided polyethylene suture (suture group), with 8 specimens in each group. An inferiorly directed force was applied to the anterior acromion at 1 mm/s on a materials testing machine. Stiffness and ultimate failure load were recorded and analyzed.

RESULTS

No significant difference (P = .22) was observed in the ultimate failure load between the wire (228  ± 85 N; range, 114-397 N) and the suture (275 ± 139 N; range, 112-530 N). No significant difference (P = .17) was observed in the stiffness between the wire (28  ± 12 N/mm; range, 18-53 N/mm) and the suture (38  ± 25 N/mm; range, 10-83 N/mm).

CONCLUSIONS

Stainless steel wire and polyethylene suture have similar biomechanical strength in the cannulated screw tension band fixation of meso-type os acromiale at time zero.

Glenoid Dysplasia

Glenoid dysplasia is a developmental anomaly of the scapula that is characterized by a bony deficiency of the posteroinferior glenoid and the adjacent scapular neck. Glenoid dysplasia may occur as a primary isolated condition or in association with various syndromes. It is thought to be related to defective ossification of the inferior glenoid precartilage. Radiographs typically demonstrate bilateral, symmetric dysplasia of the scapular neck with a range of associated bony changes. Glenoid dysplasia has been associated with instability and premature glenohumeral arthritis, although the clinical presentation is highly variable. Symptoms are delayed or mitigated as a result of compensatory glenoid labral hyperplasia. The treatment of glenoid dysplasia remains challenging. Nonsurgical treatment is reasonably successful in younger patients, but premature degenerative changes frequently occur. Although favorable results can be obtained with the use of anatomic arthroplasty, continued subluxation and glenoid component failure can lead to unacceptable outcomes.

Differentiating os acromiale from normally developing acromial ossification centers using magnetic resonance imaging

OBJECTIVE

Acromial fusion may not be complete until age 18-25, making it questionable to diagnose os acromiale in adolescents. Os acromiale may exist in adolescents and can be differentiated from a developing acromial ossification center based on MRI findings.

MATERIALS AND METHODS

A total of 128 MRIs of the shoulder were randomly and blindly reviewed retrospectively by two musculoskeletal radiologists. The MRIs consisted of two groups: (1) 56 of os acromiale in adults (25-74 years old, mean, 50) and (2) 72 consecutive of adolescents (12-17 years old, mean, 14.5). The following were assessed at the interface between the distal acromion and os acromiale/developing ossification center(s): presence of os acromiale vs. developing acromion, orientation, margins, and edema within and adjacent to it.

RESULTS

Fifty-one adults and 49 adolescents were included. Exclusions were due to poor image quality or confounding findings (n = 7) or complete acromial fusion (n = 21 adolescents). Utilizing accepted definitions of os acromiale, all adult cases (100 %) were accurately diagnosed as os acromiale, with transverse interface orientation and irregular margins (94 %, R = 0.86, p < 0.00001). Forty-five (92 %) adolescent cases were accurately diagnosed as normally developing acromion with arched interface and lobulated margins (92 %, R = 0.92, p < 0.000001). Four (8 %) adolescent cases were diagnosed as having os acromiale, with transverse orientation and irregular margins. Thirty-five (69 %) and 46 (90 %) adults had marrow and interface edema, respectively. Six (12 %) and eight (16 %) adolescents had marrow and interface edema, respectively, including the four concluded to be os acromiale.

CONCLUSIONS

Adolescents may have imaging findings consistent with os acromiale. The diagnosis of os acromiale should be based on imaging features and not limited by age.

Skeletal developmental patterns in the acromial process and distal clavicle as observed by MRI

OBJECTIVE

To provide an MRI timeline of normal skeletal developmental patterns in the acromial process and distal clavicle in children up to 18 years of age.

MATERIALS AND METHODS

Retrospective review of all shoulder MRIs obtained at our institution between January 2003 and March 2012, in children up to age 18, was performed. When available, radiographs and CT scans for these children were also reviewed. The following variables of the distal acromion and clavicle, with attention to morphology and MRI signal, were assessed: (1) Chondro-osseous junction and (2) Development and fusion of the secondary ossification centers.

RESULTS

Ninety-eight children with 116 MR studies were identified from the data search. Of these, 13 patients were excluded and the final cohort included 85 children with 102 MRI studies. Forty-one of these patients also had shoulder radiographs. The cartilaginous precursors of the distal clavicle and acromion conformed to the final shape of these structures. The chondro-osseous interphases became progressively more lobulated and notched in the distal acromion and clavicle respectively. Appearance and fusion of the secondary ossification centers was significantly earlier in our study than previously reported. Acromial secondary ossification centers began forming at age 10 and clavicular ones, while uncommon, began forming at age 11. Fusion of acromial primary and secondary ossification centers began at age 14 and was generally complete after age 16.

CONCLUSIONS

Based on MR imaging the development and fusion of the acromion and distal clavicle in children occur earlier than previously reported. They follow a sequential pattern and can serve as a blueprint for evaluating imaging studies of pediatric shoulders.

Scapula fracture and os acromiale after reverse total shoulder arthroplasty

An 80-year-old woman underwent a right reverse total shoulder arthroplasty for cuff tear arthropathy with no complications. She was discharged 3 days after surgery with well-controlled pain. However, 6 days postoperatively, she reported the onset of excruciating pain in her right shoulder, and conventional radiographs, including an axillary radiograph, were obtained.

Shoulder arthroplasty for osteoarthritis secondary to glenoid dysplasia: an update

BACKGROUND

Glenoid component fixation is an issue in shoulder arthroplasty for glenoid dysplasia with osteoarthritis because of the small amount of bone available. In 2002, we described 6 patients (7 shoulders) undergoing shoulder arthroplasty for this condition. This report expands that experience to further understand the role of anatomic shoulder arthroplasty (both hemiarthroplasty and total shoulder arthroplasty), to outline results, and to identify complications and reoperations-all to better understand whether other treatment options need to be developed and explored. Our hypothesis is that treatment of this problem with anatomic arthroplasty is not ideal.

METHODS

Between 1980 and 2008, 20 patients (22 shoulders) underwent anatomic shoulder arthroplasty for treatment of osteoarthritis secondary to glenoid dysplasia. There were 8 hemiarthroplasties and 14 total shoulder arthroplasties. Average follow-up was 6 years (range, 0.4 to 23.1 years).

RESULTS

Pain was relieved in 4 of 8 shoulders undergoing hemiarthroplasty and in 10 of 14 shoulders undergoing total arthroplasty. Mean active elevation improved from 96° to 125°, and external rotation improved from 19° to 42°. Motion improvements were similar for hemiarthroplasty and total shoulder arthroplasty. Four shoulders having hemiarthroplasty underwent revision surgery because of painful glenoid arthrosis. Two shoulders with total arthroplasty underwent revision for infection, and 3 underwent revision for glenoid component issues.

CONCLUSION

Favorable results can be obtained with the use of anatomic implants in the treatment of glenoid dysplasia. However, continuing subluxation, glenoid arthrosis, and glenoid component problems necessitating revision surgery are frequent. Alternative treatment methods should be considered.

The prevalence of Os acromiale: a systematic review and meta-analysis

Os acromiale (OA) results from a failure of consolidation between the ossification centers of the acromial epiphysis. Its prevalence and its interactions with ancestry, gender, laterality, and side have been variously reported in the literature. The aims of this review are to provide an accurate estimate of OA prevalence and to investigate its association with other variables in an attempt to comprehend its etiology. Twenty-three studies met the inclusion criteria. The results of meta-analyses of large-sample studies revealed: (a) a crude overall prevalence of 7.0%, (b) a crude cadaveric prevalence of 7.6%, (c) a crude archeological (skeletal) prevalence of 5.6%, (d) a crude radiological prevalence of 4.2%, (e) a true anatomical prevalence of 9.6%, (f) a significantly higher frequency in persons of black ancestry than in persons of white, Native American and Middle Eastern ancestries (OR ≈ 3), (g) significantly higher unilateral and bilateral frequencies in black ancestry (OR of 2 and 4, respectively), (h) nonsignificant interactions of OA frequency with gender and side. The commonest type of OA was the meso-acromion type (76.6%). Degenerative changes were present in 66.6% of OAs. The results of this evidence-based anatomical review support a genetic basis for OA rather than the mechanical trauma-induction hypothesis.

Os acromiale: a review and an introduction of a new surgical technique for management

Os acromiale is a common finding in shoulder surgery. We review the anatomy, prevalence, pathophysiology, and treatment options for this diagnosis. In addition, we report on a case series of 6 patients with a symptomatic meso os acromiale who were treated with a new technique involving arthroscopic acromioplasty in conjunction with the excision of the acromial nonunion site. We have demonstrated this novel treatment method to be a safe and effective technique in this case series. This arthroscopic partial resection of an os acromiale is considered to be an alternative option for treating a symptomatic meso os acromiale.

Unilateral duplication of the acromioclavicular joint: case report and literature review

Clavicle duplication is a rare anatomical variation of the scapular belt: only seven cases have been reported in the literature to date, and only one took note of the existence of a duplication of the acromioclavicular joint. Two hypotheses have been proposed to interpret this variation: genetic factors, or trauma occurred in the growth period. Clavicle duplication should not be mistaken for a quite frequent coracoclavicular joint widely described. The authors report the case of a left acromioclavicular joint duplication in a 51-year-old male patient presenting with left shoulder pain. This case was the first of literature providing 3D CT-scan images.

Systematic review of the surgical treatment for symptomatic os acromiale

The optimal surgical treatment for symptomatic os acromiale that has failed nonoperative management is unclear in the literature. We conducted a systematic review of multiple medical databases for level I–IV evidence. Both radiographic and clinical outcomes were analyzed. Nine studies met the inclusion criteria (118 subjects, 125 shoulders). One hundred and fifteen subjects were treated surgically (122 shoulders). The mean age of the subjects was 49±11 years. The mean preoperative duration of symptoms was 12±8.6 months. Mesoacromiale was the most common type treated (94%). Internal fixation was the most common surgical technique used (60%), followed by excision (27%) and acromioplasty (13%). Rotator cuff repair was the most common concurrent surgical technique (performed in 59% of the surgically treated shoulders), followed by distal clavicle excision (25%). All surgical techniques resulted in improvement in clinical outcomes. Surgical management of symptomatic os acromiale that has failed nonoperative measures may predictably lead to improved outcomes.

Previously unreported structure associated with Sprengel deformity

Congenital elevation of the scapula (Sprengel deformity) is the most common congenital abnormality involving the scapula. In up to 50% of cases, there is an associated connection, which may be osseous, cartilaginous, or fibrous, between the scapula and the lower cervical spine. To date, there have been no reports of an osseous structure extending from the medial scapula to the clavicle and occipital region of the skull associated with Sprengel deformity.

Symptomatic os acromiale

Os acromiale, the joining of the acromion to the scapular spine by fibrocartilaginous tissue rather than bone, is an anatomic variant that has been reported in approximately 8% of the population worldwide. It is more common in blacks and males than in whites and females. Although it is often an incidental finding, os acromiale has been identified as a contributor to shoulder impingement symptoms and rotator cuff tears. When nonsurgical management of a symptomatic os acromiale fails to relieve symptoms, surgical intervention is considered. Options include os acromiale excision, open reduction and internal fixation, and arthroscopic decompression. Excision usually is reserved for small to midsized fragments (preacromion) or after failed open reduction and internal fixation. Persistent deltoid dysfunction may result from excision of a large os acromiale. Open reduction and internal fixation preserves large fragments while maintaining deltoid function. Cannulated screw fixation has been shown to result in good union rates. Arthroscopic techniques have shown mixed results when used for treating impingement secondary to an unstable os acromiale. Associated rotator cuff tears may be addressed arthroscopically or through an open transacromial approach, followed by open reduction and internal fixation of the os acromiale.

Rotator cuff tears associated with os acromiale

INTRODUCTION

Os acromiale is a rare anatomical condition; its incidence in cadaver studies has been found to be approximately 8%. In this retrospective study we investigated the incidence and types of os acromiale in patients with rotator cuff tears.

METHODS

We assessed operation notes and axillary radiographs for the presence and the type of os acromiale in 1000 consecutive patients with open rotator cuff repairs.

RESULTS

62 patients (6.2%) showed an os acromiale in the axillary radiographs. In 6 of these the os acromiale was not described in the operation notes. 57 os meso-acromiale and 5 os pre-acromiale were found. The average number of tendons involved in the cuff tear was the same (1.4) in patients with and without os acromiale. The average age of patients with os acromiale was 55 years, and 56 years in patients without os acromiale.

INTERPRETATION

Os acromiale is a co-condition in patients with rotator cuff tear. The prevalence of os acromiale in patients with rotator cuff tear is similar to that in a standard population with unknown integrity status of the rotator cuff. Thus, it seems debatable whether an os acromiale is a pathological condition leading to rotator cuff tears.

Radiographic analysis of the acromion in the loose shoulder

To investigate the contribution of bony stability to the pathogenesis of the loose shoulder, geometric parameters of the acromion by use of cineradiography were evaluated in patients with a loose shoulder and compared with those in the normal shoulder. One hundred twenty healthy individuals and eighty-two patients were enrolled. To evaluate the size of the acromion and the coverage of the humeral head by the acromion, the anterior width of the acromion and three angle parameters were measured. The findings demonstrated that the loose shoulder had a relatively smaller and more upwardly inclined acromion that was against the glenoid and provided less coverage of the humeral head. These characteristics of the acromion may contribute to the hypermobility and functional instability of the shoulder joint observed in patients with a loose shoulder. Therefore, a radiographic evaluation of the geometry of the acromion is important to determine the pathogenesis of the loose shoulder.

Developmental anomalies of the scapula-the "omo"st forgotten bone

Congenital malformations of the scapula, ranging from complete absence, to abnormal shape and position (Sprengel anomaly) are encountered, not infrequently, in genetic practice. Despite this, little is known of the embryologic origin of the scapula and the relationship of the embryology to the observed birth defects. Standard embryology texts, when discussing the subject at all, generally consider the scapula as part of the upper limb. The pattern of associated birth defects suggests that this is at least an oversimplification and may be inaccurate. Sprengel anomaly is the most frequently encountered malformation of the scapula. It can be seen in isolation, but is often seen in association with other defects that include; scoliosis, hemivertebrae, segmentation abnormalities of vertebrae and ribs (including Klippel-Feil sequence), spina bifida, clavicular abnormalities, renal abnormalities and hypoplasia of the muscles of the neck and shoulder. The ipsilateral limb is usually normal. An unappreciated association between Sprengel anomaly and diastematomyelia of the lumbar spine also raises questions about the embryologic origin of the scapula. 25-50% of Sprengel anomaly patients have an associated omovertebral band or bone that arises from the posterior process of a vertebral body and attaches to the superior angle/medial portion of the scapula. This is felt to be of scapular origin, but the report of at least one patient with an omovertebral bone, not associated with a Sprengel anomaly questions this assumption. Scapuloiliac dysostosis (Kosenow syndrome), a rare skeletal dysplasia, is associated with marked hypoplasia of the scapulae, clavicles and pelvis. Associated anomalies include eye anomalies, rib anomalies and spina bifida. The limbs are normal. Knockout of the Emx2 gene in mice yields a similar skeletal phenotype. Mutations in EMX2 in humans are associated with schizencephaly, not skeletal anomalies. Data on gene expression in the scapula will be reviewed. Based on this information, the author proposes that the scapula arises from 2 or more distinct embryologic anlage under different genetic control than the upper limb.

Complications of treatment of acromioclavicular and sternoclavicular joint injuries

Although common, AC joint injuries and their treatments are not benign. The injury itself and both nonsurgical and surgical treatments may result in complications yielding persistent pain, deformity, or dysfunction. Sternoclavicular joint injuries are far less common and are typically the result of higher energy trauma. As such, the associated complications may be more serious. Familiarity with the potential complications of these injuries can help the treating physician to develop strategies to minimize their incidence and sequelae.

Arthroscopic decompression for impingement syndrome secondary to an unstable os acromiale

PURPOSE

The purpose of this study was to examine cases of patients with impingement syndrome secondary to an unfused, unstable, os acromiale.

TYPE OF STUDY

Retrospective case series.

MATERIALS AND METHODS

Twelve consecutive patients (13 shoulders) presented with impingement symptoms in the presence of an os acromiale. The os acromiale, at the meso-acromion level, was seen on standard radiographs. The patients were all treated conservatively with rotator cuff strengthening, stretching, anti-inflammatory medications, and steroid injections. All patients underwent an impingement test with lidocaine, resulting in complete relief of their pain. After failure of the conservative management, the 12 patients (13 shoulders) underwent an extended arthroscopic subacromial decompression. The goal of the modified arthroscopic acromioplasty was resection of adequate bone to remove the mobile anterior acromial tip. In general, this consisted of more bony resection than the typical arthroscopic acromioplasty. Postoperatively, the patients began a rehabilitation program emphasizing early range of motion followed by isolated free-weight rotator cuff strengthening exercises. Five shoulders had a partial-thickness tear of the rotator cuff. Four involved less than 50% of the thickness of the rotator cuff. These 4 partial-thickness tears underwent arthroscopic rotator cuff debridement. One partial-thickness tear was greater than 50% and repair was performed with a mini-open deltoid-splitting technique.

RESULTS

Results were evaluated using UCLA shoulder scoring. Preoperatively, the score averaged 17. The 3-month postoperative score was 27, and at 6 and 12 months, averaged 28. The final follow-up score averaged 31. There were 11 satisfactory results with UCLA scores >/=28. Two unsatisfactory results showed UCLA scores in the fair category. Full strength of the anterior deltoid and rotator cuff muscles was achieved in all patients by 6 months postoperatively as evaluated by manual muscle testing. Twelve of the 13 shoulders were rated by the patients as having a satisfactory result. All of the patients rated their cosmetic results as acceptable. There was no evidence of postoperative deltoid detachment. No patient developed pain at the pseudarthrosis point.

CONCLUSIONS

Given the previously reported poor results with attempts at fusion of an unstable os acromiale and open complete excision of meso-acromial fragments, the authors conclude that an extended arthroscopic subacromial decompression results in a reasonable outcome for patients with impingement syndromes secondary to an unstable os acromiale.

Os acromiale: frequency, anatomy, and clinical implications

BACKGROUND

Os acromiale is present when the anterior portion of the acromion has one or more separate ossicles. Its frequency has been documented, in radiographic and anatomical studies, to be between 1 and 15 percent. Reports of os acromiale associated with subacromial pathology have been cited to imply that this entity is a cause of subacromial impingement; however, no study has demonstrated an increased frequency of os acromiale in patients with shoulder pain compared with the frequency in the general population. Inconsistencies in the literature concerning anatomy, development, and frequency prompted the current anatomical study. The purpose of this study was to better define the frequency and anatomy of os acromiale in the general population.

METHODS

Two thousand three hundred and sixty-seven scapular bones from 1198 human skeletons from the Hamann-Todd Osteological Collection were studied for evidence of os acromiale. The sample consisted of specimens from 1033 men and 165 women, 843 of whom had been white and 355, black. The mean age of the individuals at the time of death was 44.7 years (range, eighteen to eighty-nine years). The frequency of os acromiale was noted, and the specimens were measured.

RESULTS

There were 128 cases of os acromiale in ninety-six (8.0 percent) of the 1198 skeletons, and the condition was bilateral in thirty-two (33.3 percent) of the ninety-six skeletons. In twenty cases, the free fragment had been lost but it was assumed that a fragment had been present because the acromion was truncated. Os acromiale was more frequent in blacks than in whites (13.2 compared with 5.8 percent; p < 0.001) and in men than in women (8.5 compared with 4.9 percent; p = 0.09). The mean proportional length of the free fragment was 0.42 compared with the overall length of the acromion. Care was taken to differentiate os acromiale from a normal immature acromion. Six skeletons demonstrated persistent acromial apophyses. All six cases were bilateral; seven fragments were fusing, and five were free. The oldest age at which a persistent normal apophysis was found was twenty-one years. The frequency of os acromiale in specimens from individuals who had been less than twenty-two years old was not significantly different from that in the remainder of the collection (p = 0.74). Twenty-one scapulae had a distinct circumferential line that was suggestive of an acromial joint, but the distal and proximal portions were solidly fused. However, the findings on plain axillary radiographs of sixteen of these specimens were indistinguishable from those of specimens with os acromiale.

CONCLUSIONS

An anatomical study, performed to better define the frequency and anatomy of os acromiale in the general population, showed that fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting.

Familial congenital bilateral agenesis of the acromion: a radiologically illustrated case report

Familial congenital bilateral acromion absence was found in four members of one family. Only one of them presented with gradually increasing pain in his left shoulder, resembling a shoulder impingement syndrome. The other members did not have any symptoms. This is the first report of familial occurrence of this extremely rare congenital anomaly.

A practical approach to imaging of the shoulder with emphasis on MR imaging

Our understanding of shoulder disorders has changed considerably as a result of improved diagnostic tools, such as arthroscopy and multiplanar imaging modalities. The diagnosis of the cause of shoulder pain can be difficult because a spectrum of disorders, including cervical spine disease, acromioclavicular arthritis, and shoulder instability. Impingement and denervation syndromes can present with similar clinical findings. Accurate depiction of anatomic abnormalities is important for treatment planning. The purpose of this article is to report on the application of available imaging modalities, with emphasis on MR imaging. A strategy for the appropriate use of these studies and their variations of technique is also provided.

Fractures of the acromion in young children and a description of a variant in acromial ossification which may mimic a fracture

We report on six children, from 2 to 19 months old, with a defect across the root of the acromion (basiacromion) diagnosed as a fracture in four and as an anatomical variant (separate ossification center for the lateral half of the basiacromion) in the other two.

Hypoplasia of the glenoid. A review of sixteen patients

We reviewed the records of sixteen patients, fifteen to sixty-two years old, who had glenoid hypoplasia with or without an associated deformity of the humeral head. The patients were divided into three groups: those who had bilateral glenoid hypoplasia without instability of the shoulder (Group I), those who had bilateral glenoid hypoplasia with instability of the shoulder (Group II), and those who had unilateral glenoid hypoplasia with deformity of the humeral head (Group III). When first seen by us, thirteen of the sixteen patients had pain in the shoulder, which they had noted after an increase in their previous level of activity. All were managed with a specific rehabilitation program for the shoulder. The patients were followed for an average of five years, and most were able to return to their previous level of activity with the resolution of the symptoms.

Arthroscopic decompression of shoulder impingement secondary to Os acromiale

Os acromiale is the result of failure of one of the outer ossification centers of the acromion to unite with the more medial portion. This creates an additional motion segment which may itself contribute to impingement syndrome of the shoulder or which may create hypertrophy or spurs which directly impinge on the cuff. Three cases of impingement syndrome of the shoulder with associated os acromiale are presented. All three were initially relieved with arthroscopic subacromial decompression of either the entire os acromiale or simply of the impinging spur. After 1 year, however, all three had recurrent or continued complaints of pain and/or impingement. Therefore, it would appear that arthroscopic subacromial decompression is not a solution to impingement syndrome secondary to os acromiale. Careful preoperative radiographic evaluation to rule out all causes of impingement syndrome including os acromiale is essential so that the surgeon may better choose an approach to decompression.

Glenoid hypoplasia: assessment by computed tomographic arthrography

Four cases of an uncommon congenital skeletal anomaly, isolated bilateral glenoid hypoplasia, are presented with discussion of the possible pathogenesis and clinical significance. Bilateral computed tomographic arthrography of the shoulder demonstrated thickening of the inferior glenoid cartilage in two cases. The technique was of value in the symptomatic shoulder revealing the location of a contrast medium filled cleft within the posterior cartilage in one case and the true configuration of the glenohumeral joint in the second case, when the degree of deformity had rendered plain radiographs and conventional arthrography uninterpretable.

Scapular foramina

Although foramina in the scapula are a rare occurrence, they produce radiolucent defects that simulate those related to skeletal metastasis or multiple myeloma. In order to define the typical location and appearance of these foramina, we initiated a radiographic and pathologic examination of macerated modern and ancient scapulae. Of 93 macerated scapulae that were examined, foramina were observed in 27 specimens (29%). These occurred at four sites: at the superior border of the bone at its junction with the coracoid process, caused by ossification of the superior transverse ligament (21 specimens); in the body of the bone inferior to the scapular spine, resulting from a disturbance in ossification during fetal development (five specimens); in the superior fossa, as a clasp-like defect (one specimen); and, at the superomedial border above the scapular spine (one specimen). The radiographic features of these foramina were compared to those produced by normal vascular channels, anatomic thinning of the bone, and skeletal metastasis or multiple myeloma. Knowledge of the typical appearance and site of scapular foramina assures accurate diagnosis.

Bilateral dysplasia of the neck of scapula and associated anomalies

Nine cases of bilateral dysplasia of the neck of scapula, combined with a varying degree of hypoplasia and varus position of the humeral head as well as enlargement of the acromion are described. The relation between the clinical and radiologic findings is analysed. Bilateral dysplasia of the neck of scapula with its associated anomalies seems to be a hereditary entity, producing only slight discomfort to the patient. It might be more common than previously assumed.