INTRODUCTION: Full thickness rotator cuff tears have been associated with changes of the anterior acromion. In a previous study we also documented differences in lateral extension of the acromion in rotator cuff tears compared with shoulders with intact cuffs. It was the purpose of this study to verify in a prospective examination, whether presence or absence of rotator cuff tearing in a precisely defined population is quantitatively related to the degree of lateral extension of the acromion. MATERIAL AND METHODS: 59 consecutive patients between 60 and 70 years and hospitalized for reasons other than shoulder pathologies were entered into a prospective study. All 110 shoulders without previous operations, major trauma or rheumatoid arthritis were examined radiographically and with ultrasonography by two independent examiners. RESULTS: 67 cuffs were intact, 28 showed a cuff tendinopathy, 17 a full thickness tearing. The acromion index for shoulder with rotator cuff tear was 0.75, for tendinopathy 0.68 and for normal cuffs 0.65. The differences between rotator cuff tears and the other two groups was significant (p< 0.05). The acromion index was not related to gender or osteoarthritis. An acromion index of < 0.77 had a positive predictive value of > 70%. An acromion index of < 0.7 predicted an absence of rotator cuff tearing with an accuracy of 97%. Interobserver agreement of the assessment was excellent with 88%. CONCLUSION: The relationship between rotator cuff tears and a large extension of the acromion can be used to predict the presence of rotator cuff tears in shoulders between ages 60 and 70. A cause-effect relation is probable and will be studied further

Rotator cuff pathologies are related with higher incidence of morbidity in the modern society in young patients. Although it is well known that rotator cuff is sandwiched between the acromion and humeral head during various movements of the shoulder joint, only few studies have investigated this looking at the humeral head as a culprit for the rotator cuff pathology. We carried out the cadaveric study of 15 shoulder joints to find out the influence of the humeral head anatomy on the rotator cuff pathology. We dissected 15 shoulder joints and looked at the rotator cuff tears. All the specimens were examined and photographed digitally from the superior aspect of shoulder joint. All these images were entered into a computer and using special software, we carried out 3D reconstruction of these images. With this software, the outermost point of intersection of humerus head with acromion decided. We calculated the area of the humeral head in an outside the acromion and correlated with the rotator cuff tear. We found that the area of the humeral head outside the acromion is variable, ranging from 18% to 50% of diameter of humeral head (mean 34%, median 33%, mode 20%, 33%, 45%). When the area of humerus head outside the acromion is less than 32% of the diameter of head (i.e. humerus head was more under the acromion and less outside the outer most point of acromion), those specimens had either incomplete or complete rotator cuff tear. We conclude that when the area of humeral head, covered under the acromion is more than 68% of the diameter of the head, they have more chances of developing rotator cuff pathology as compare to other individual

1. The supraspinatus group of lesions constitutes one of the two common causes of the painful shoulder. 2. Most, but not all, of these lesions resolve either spontaneously or after conservative treatment. 3. When conservative treatment fails symptoms can be relieved by excision of the acromion process, provided that sufficient bone is removed to relieve all pressure on the tendon throughout a full range of shoulder movement. 4. Excision of the acromion is contra-indicated if there is doubt as to the diagnosis or if there is true limitation of shoulder movement

Examination was made of 750 scapular dry bone specimens from museum collections and 80 cadaver shoulders. Hooking of the acromion was not found in subjects under the age of 30 years. The hooked configuration developed at later ages in an increasing proportion of subjects as a result of calcification of the acromial attachment of the coracoacromial ligament

We examined 200 scapular bones for signs of degenerative changes in the coraco-acromial arch. The slope and length of the acromion and the height of the arch were found to be most closely associated with degenerative change. These anatomical features are not significantly altered by current techniques of subacromial decompression

Lateral clavicular physeal injuries in adolescents are frequently misinterpreted as acromioclavicular dislocations. There are currently no clear guidelines for the management of these relatively rare injuries. Non-operative treatment can result in a cosmetic deformity, warranting resection of the non-remodelled original lateral clavicle. However, fixation with Kirschner (K)-wires may be associated with infection and/or prominent metalwork. We report our experience with a small series of such cases.

Between October 2008 and October 2011 five patients with lateral clavicular physeal fractures (types III, IV and V) presented to our unit. There were four boys and one girl with a mean age of 12.8 years (9 to 14). Four fractures were significantly displaced and treated operatively using a tension band suture technique. One grade III fracture was treated conservatively. The mean follow-up was 26 months (6 to 42).

All patients made an uncomplicated recovery. The mean time to discharge was three months. The QuickDASH score at follow-up was 0 for each patient. No patient developed subsequent growth disturbances.

We advocate the surgical treatment of significantly displaced Grade IV and V fractures to avoid cosmetic deformity. A tension band suture technique avoids the problems of retained metalwork and the need for a secondary procedure. Excellent clinical and radiological results were seen in all our patients.

Cite this article: Bone Joint J 2013;95-B:664–7.

In patients with shoulder arthritis, the ability to accurately determine glenoid morphological alterations affects the outcomes of shoulder arthroplasty surgery significantly. This study was conducted to determine whether there is a correlation between scapular and glenoid morphometric components. Existence of such a correlation may help surgeons accurately estimate glenoid bone loss during pre-operative planning. The dimensions and geometric relationships of the scapula, scapula apophysis and glenoid were assessed using CT scan images of 37 South African and 40 Chinese cadavers. Various anatomical landmarks were marked on the 77 scapulae and a custom script was developed to perform the measurements. Intra-cohort correlation and inter-cohort differences were statistically analysed using IBM SPSS v28. The condition for statistical significance was p<0.05. The glenoid width and height were found to be significantly (p<0.05) correlated with superior glenoid to acromion tip distance, scapula height, acromion tip to acromion angle distance, acromion width, scapula width, and coracoid width, in both the cohorts. While anterior glenoid to coracoid tip distance was found to be significantly correlated to glenoid height and width in the South African cohort, it was only significantly correlated to glenoid height in the Chinese cohort. Significant (p<0.05) inter-cohort differences were observed for coracoid height, coracoid width, glenoid width, scapula width, superior glenoid to acromion tip distance, and anterior glenoid to coracoid tip distance. This study found correlations between the scapula apophyseal and glenoid measurements in the population groups studied. These morphometric correlations can be used to estimate the quantity of bone loss in shoulder arthroplasty patients

Os acromiale is a developmental defect caused by failure of fusion of the anterior epiphysis of the acromion between the ages of 22 and 25. The prevalence of os acromiale in the general population ranges from 1.4% to 15%. Os acromiale has been reported as a contributory factor to shoulder impingement symptoms and rotator cuff injuries, despite being a common incidental observation. In this retrospective study, we examined the prevalence of os acromiale in black African patients with shoulder pain. We retrospectively reviewed the clinical records, radiographs, and magnetic resonance imaging (MRI) scans of 119 patients who presented with atraumatic and minor traumatic shoulder pain at a single institution over a one-year period. Anteroposterior, scapula Y-view, and axillary view plain images were initially evaluated for the presence of os acromiale, and this was corroborated with axial MRI image findings. Patients with verified os acromiale had their medical records reviewed to determine their first complaint and the results of their clinical examination and imaging examination. Radiographs and MRI on 24 patients (20%) revealed an osacromiale. This cohort had a mean age of 59.2 years, and there were significantly more females (65%) than males. Meso-acromion was identified as the most prevalent type (n=11), followed by pre-os acromion (n=7). All patients underwent bilateral shoulder x-rays, and 45 percent of patients were found to have bilateral meso- acromion. Most patients (70%) were reported to have unstable os acromiale with subacromial impingement symptoms, and nine patients (36%) had confirmed rotator cuff tears based on clinical and Mri findings. Surgery was necessary for 47% of the 24 patients with confirmed Os acromiale (arthroscopic surgery, n=7; open surgery, n=1) in order to treat their symptoms. The prevalence of os acromiale in our African patients with atraumatic shoulder symptoms is greater than that reported in the general population. Os acromiale is a rare condition that should always be considered when evaluating shoulder pain patients

Acromial morphology has been implicated as a risk factor for unidirectional posterior shoulder instability. Studies utilising plain film radiographic landmarks have identified an increased risk of posterior shoulder dislocation in patients with higher acromion positioning. The aims of this study were to develop a reproducible method of measuring this relationship on cross sectional imaging and to evaluate acromial morphology in patients with and without unidirectional posterior shoulder instability. We analysed 24 patients with unidirectional posterior instability. These were sex and age matched with 61 patients with unidirectional anterior instability, as well as a control group of 76 patients with no instability. Sagittal T1 weighted MRI sequences were used to measure posterior acromial height relative to the scapular body axis (SBA) and long head of triceps insertion axis (LTI). Two observers measured each method for inter-observer reliability, and the intraclass correlation coefficient (ICC) calculated. LTI method showed good inter-observer reliability with an ICC of 0.79. The SBA method was not reproducible due suboptimal MRI sequences. Mean posterior acromial height was significantly greater in the posterior instability group (14.2mm) compared to the anterior instability group (7.7mm, p=0.0002) as well when compared with the control group (7.0mm, p<0.0001). A threshold of 7.5mm demonstrated a significant increase in the incidence of posterior shoulder instability (RR = 9.4). We conclude that increased posterior acromial height is significantly associated with posterior shoulder instability. This suggests that the acromion has a role as an osseous restraint to posterior shoulder instability

Knowledge of the premorbid glenoid shape and the morphological changes the bone undergoes in patients with glenohumeral arthritis can improve surgical outcomes in total and reverse shoulder arthroplasty. Several studies have previously used scapular statistical shape models (SSMs) to predict premorbid glenoid shape and evaluate glenoid erosion properties. However, current literature suggests no studies have used scapular SSMs to examine the changes in glenoid surface area in patients with glenohumeral arthritis. Therefore, the purpose of this study was to compare the glenoid articular surface area between pathologic glenoid cavities from patients with glenohumeral arthritis and their predicted premorbid shape using a scapular SSM. Furthermore, this study compared pathologic glenoid surface area with that from virtually eroded glenoid models created without influence from internal bone remodelling activity and osteophyte formation. It was hypothesized that the pathologic glenoid cavities would exhibit the greatest glenoid surface area despite the eroded nature of the glenoid and the medialization, which in a vault shape, should logically result in less surface area. Computer tomography (CT) scans from 20 patients exhibiting type A2 glenoid erosion according to the Walch classification [Walch et al., 1999] were obtained. A scapular SSM was used to predict the premorbid glenoid shape for each scapula. The scapula and humerus from each patient were automatically segmented and exported as 3D object files along with the scapular SSM from a pre-operative planning software. Each scapula and a copy of its corresponding SSM were aligned using the coracoid, lateral edge of the acromion, inferior glenoid tubercule, scapular notch, and the trigonum spinae. Points were then digitized on both the pathologic humeral and glenoid surfaces and were used in an iterative closest point (ICP) algorithm in MATLAB (MathWorks, Natick, MA, USA) to align the humerus with the glenoid surface. A Boolean subtraction was then performed between the scapular SSM and the humerus to create a virtual erosion in the scapular SSM that matched the erosion orientation of the pathologic glenoid. This led to the development of three distinct glenoid models for each patient: premorbid, pathologic, and virtually eroded (Fig. 1). The glenoid surface area from each model was then determined using 3-Matic (Materialise, Leuven, Belgium). Figure 1. (A) Premorbid glenoid model, (B) pathologic glenoid model, and (C) virtually eroded glenoid model. The average glenoid surface area for the pathologic scapular models was 70% greater compared to the premorbid glenoid models (P < 0 .001). Furthermore, the surface area of the virtual glenoid erosions was 6.4% lower on average compared to the premorbid glenoid surface area (P=0.361). The larger surface area values observed in the pathologic glenoid cavities suggests that sufficient bone remodelling exists at the periphery of the glenoid bone in patients exhibiting A2 type glenohumeral arthritis. This is further supported by the large difference in glenoid surface area between the pathologic and virtually eroded glenoid cavities as the virtually eroded models only considered humeral anatomy when creating the erosion. For any figures or tables, please contact the authors directly

In a prospective randomised study we compared the results of arthroscopic subacromial bursectomy alone with debridement of the subacromial bursa followed by acromioplasty. A total of 57 patients with a mean age of 47 years (31 to 60) suffering from primary subacromial impingement without a rupture of the rotator cuff who had failed previous conservative treatment were entered into the trial. The type of acromion was classified according to Bigliani. Patients were assessed at follow-up using the Constant score, the simple shoulder test and visual analogue scores for pain and functional impairment. One patient was lost to follow-up. At a mean follow-up of 2.5 years (1 to 5) both bursectomy and acromioplasty gave good clinical results. No statistically significant differences were found between the two treatments. The type of acromion and severity of symptoms had a greater influence on the clinical outcome than the type of treatment. As a result, we believe that primary subacromial impingement syndrome is largely an intrinsic degenerative condition rather than an extrinsic mechanical disorder

Aims: Most of the orthopaedic literature on os acromiale (OA) is focused on corresponding clinical implication, such as impingement syndrome and rotator cuff tear; whilst, although it is present in 8% of subjects, scarce information is reported on the causes that may predispose to it. Our aim is to investigate whether the origin of OA is related to position of AC joint. Methods: The acromions of 211 volunteers (control group) and 33 subjects, respectively, without or with OA have been radiographically (axillary view) classiþed in accordance to the Edelson and Taitzñ method. The latter distinguishes the acromion in three types on the basis of the distance between the anterior aspect of the acromion and AC joint. Out of 33 subjects with os acromiale, 11 were shoulder painless. We have compared among them the frequencies of the types of acromion observed in the two investigated cohorts. Results: Half (52.1%) of the acromions of the control group had the articular facet for the AC joint on the acromion tip whilst in 45.4% facet was tip distally located. On the other hand, out of 33 subjects with OA, 18.1% and 81.1% had, respectively, AC joint lying on or distally to the acromion tip. Conclusions: Our data suggest that the longer is the distance of AC joint from the anterior edge of the acromion, the higher is the possibility that an OA origin

We examined cultured osteoblasts derived from paired samples from the greater tuberosity and acromion from eight patients with large chronic tears of the rotator cuff. We found that osteoblasts from the tuberosity had no apparent response to mechanical stimulation, whereas those derived from the acromion showed an increase in alkaline phosphatase activity and nitric oxide release which is normally a response of bone cells to mechanical strain. By contrast, we found that cells from both regions were able to respond to dexamethasone, a well-established promoter of osteoblastic differentiation, with the expected increase in alkaline phosphatase activity. Our findings indicate that the failure of repair of the rotator cuff may be due, at least in part, to a compromised capacity for mechanoadaptation within the greater tuberosity. It remains to be seen whether this apparent decrease in the sensitivity of bone cells to mechanical stimulation is the specific consequence of the reduced load-bearing history of the greater tuberosity in these patients

We assessed the predictive value of the macroscopic and detailed microscopic appearance of the coracoacromial ligament, subacromial bursa and rotator-cuff tendon in 20 patients undergoing subacromial decompression for impingement in the absence of full-thickness tears of the rotator cuff. Histologically, all specimens had features of degenerative change and oedema in the extracellular matrix. Inflammatory cells were seen, but there was no evidence of chronic inflammation. However, the outcome was not related to cell counts. At three months the mean Oxford shoulder score had improved from 29.2 (20 to 40) to 39.4 (28 to 48) (p < 0.0001) and at six months to 45.5 (36 to 48) (p < 0.0001). At six months, although all patients had improved, the seven patients with a hooked acromion had done so to a less extent than those with a flat or curved acromion judged by their mean Oxford shoulder scores of 43.5 and 46.5 respectively (p = 0.046). All five patients with partial-thickness tears were within this group and demonstrated less improvement than the patients with no tear (mean Oxford shoulder scores 43.2 and 46.4, respectively, p = 0.04). These findings imply that in the presence of a partial-thickness tear subacromial decompression may require additional specific treatment to the rotator cuff if the outcome is to be improved further

Aims. In patients with a rotator cuff tear, tear pattern and tendon involvement are known risk factors for the development of pseudoparalysis of the shoulder. It remains unclear, however, why similar tears often have very different functional consequences. The present study hypothesizes that individual shoulder anatomy, specifically the moment arms (MAs) of the rotator cuff (RC) and the deltoid muscle, as well as their relative recruitment during shoulder abduction, plays a central role in pseudoparalysis. Materials and Methods. Biomechanical and clinical analyses of the pseudoparalytic shoulder were conducted based on the ratio of the RC/deltoid MAs, which were used to define a novel anatomical descriptor called the Shoulder Abduction Moment (SAM) index. The SAM index is the ratio of the radii of two concentric spheres based on the centre of rotation of the joint. One sphere captures the humeral head (numerator) and the other the deltoid origin of the acromion (denominator). A computational rigid body simulation was used to establish the functional link between the SAM index and a potential predisposition for pseudoparalysis. A retrospective radiological validation study based on these measures was also undertaken using two cohorts with and without pseudoparalysis and massive RC tears. Results. Decreased RC activity and improved glenohumeral stability was predicted by simulations of SAM indices with larger diameters of the humeral head, being consequently beneficial for joint stability. Clinical investigation of the SAM index showed significant risk of pseudoparalysis in patients with massive tears and a SAM < 0.77 (odds ratio (OR) 11). Conclusion. The SAM index, which represents individual biomechanical characteristics of shoulder morphology, plays a determinant role in the presence or absence of pseudoparalysis in shoulders with massive RC tears

Crosby and Colleagues described 24 scapula fractures in 400 reverse shoulder arthroplasties and classified scapula fractures after reverse shoulder arthroplasty into 3 types. Type 1 – true avulsion fracture of acromion related to a thinned out acromion (post-acromioplaty or cuff arthropathy). A small bone fragment dislodges during reduction of RSA. Type 2 – Acromial fracture due to Acromio-clavicular (AC) joint arthrosis. They feel the lack of movement at the AC joint leads to stresses across the acromion and cause it to fracture. They recommend AC joint resection and ORIF of acromion, if the acromion is unstable. Type 3 – true scapula spine fracture caused by the superior screw acting as a stress riser. This fracture occurs about 8 months after the arthroplasty and is a true stress fracture requiring open reduction and internal fixation. Of 123 reverse shoulder arthroplasties performed from Jan 2003 to Feb 2011, a total of 6 scapula fractures were encountered post-surgery. Three were acromial fractures and three were scapula spine fractures all related to trauma. The fractures of the spine occurred between 6 months and 4 years post arthroplasty. We feel the fractures were traumatic but did occur through the posterior or superior screws from the metaglen. where stress risers developed for a fracture to occur. We found that using a sliding osteotomy of the spine of the scapula to bridge the defect of the scapula and a double-plating technique using two plates at 90 degrees to each other provides a satisfactory outcome after 3–6 months where patients can start actively elevating again. This method of treatment will be presented

Neonatal and adult cadaveric studies, as well as radiological, MRI and other studies, have been undertaken to try to establish whether different acromial shapes are acquired with age or congenital. The diverse results have led to continued debate about age-related changes in acromial morphology. In this study to test the hypothesis that the acromial arch changes with age, 571 dry bone scapulae were examined. The specimens were divided into 10 groups according to age and gender. At least 50 specimens of each group were examined and classified according to the acromial types described by Bigliani. Height (h), length (l), thickness, acromial arch distance and coracoid height were measured. Because of interobserver differences in the interpretation of different acromial types, a statistical tool was devised to classify the types according to fixed parameters. This was done by calculating the acromial index (AI) with the formula AI =h/l. Type-I and type-II acromions were found in all age groups. Type-III acromions were found only in age groups above 41 years, with the incidence peaking in the over 51-year group. Type-III acromions were more common in men than woman by 8:1. Type-II acromions were the most common in both genders and all age groups, followed by type-I and then by type-III. An os acromiale was found in 12.26% of specimens. Looking at the results of this study, one has to agree with Edelson (JBJS (Br) 1995; 77-B) that type-I and type-II acromions seem to be inherited, while type-III hooked acromions are acquired

Reverse shoulder arthroplasty is becoming a frequent treatment of choice for patients with shoulder disorders. Complication rates after reverse shoulder arthroplasty may be three-fold that of conventional total shoulder arthroplasty especially in high risk patient populations and diagnoses like revision arthroplasty, fracture sequelae, and severe glenoid bone loss. Complications include component malposition, stiffness, neurological injury, infection, dislocation or instability, acromial or scapular spine fractures, scapular notching, and loosening of implants. Recognition of preoperative risk factors and appropriate 3D planning are essential in optimizing patient outcome and intraoperative success. Failure of reverse shoulder arthroplasty is a significant challenge requiring appropriate diagnosis of the failure mode. The most common neurological injuries involve the brachial plexus and the axillary nerve due to traction, manipulation of the arm, aberrant retractor placement, or relative lengthening of the arm. Intraoperative fractures are relatively uncommon but include the greater tuberosity, acromion, and glenoid. Tuberosity fracture can be repaired intraoperatively with suture techniques, glenoid fractures may be insignificant rim fractures or jeopardise baseplate fixation and require abandoning RSA until glenoid fracture ORIF heals and then a second stage RSA. Periprosthetic infection after RSA ranges from 1 to 10% and may be higher in revision cases and frequently is Propionibacterium acnes and Staphylococcus epidermidis. Dislocation was one of the most common complications after RSA approximately 5% but with increased surgeon experience and prosthetic design, dislocation rates are approaching 1–2%. An anterosuperior deltoid splitting approach has been associated with increased stability as well as subscapularis repair after RSA. Scapular notching is the most common complication after RSA. Notching may be caused by direct mechanical impingement of the humerosocket polyethylene on the scapular neck and from osteolysis from polyethylene wear. Sirveaux classified scapular notching based on the defect size as it erodes behind the baseplate towards the central post. Acromial fractures are infrequent but more common is severely eroded acromions from CTA, with osteoporosis, with excessive lengthening, and with superior baseplate screws that penetrate the scapular spine and create a stress riser. Nonoperative care is the mainstay of acromial and scapular spine fractures. Recognizing preoperative risk factors and understanding component positioning and design is essential to maximizing successful outcomes

The acromion is a bony process that juts out from the lateral end of the scapular spine. It is continuous with the blade and the spinous process. The process is rectangular, and carries a facet for the clavicle. Inferiorly is sited the subacromial bursa. Inferior encroachment or displacement of the acromion can result in impingement. The aim of this osteological study was to assess the presence of acromial displacement and variations predisposing to compaction of the subacromial space. Using the method described by Morrison and Bigliana, we assessed the scapulae of 128 men and women ranging from 35 to 92 years of age. We found a flat acromion in 30%, no hook in 48%, a small hook in 18% and a large hook in 4%. The presence of a hook was associated with a subacromial facet and a large hook with glenoid erosion. This study confirms the presence of four types of acromion