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

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

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

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

The purpose of this prospective randomised clinical trial is to examine the effect of acromioplasty on the outcome of arthroscopic rotator cuff repair. Patients included individuals that were referred for assessment after six months of failed conservative management. Following informed consent patients were randomly assigned to receive arthroscopic rotator cuff repair with or without acromioplasty. The surgeon was not blinded to the type of procedure; however, the researcher who performed the follow-up evaluations and the patient was blinded to the surgical protocol. Subacromial decompression (acromioplasty) was performed with release of the coracoacromial ligament off the anterior undersurface of the acromion. The procedure for arthroscopic cuff repair without acromioplasty followed the protocol of arthroscopic cuff repair with acromioplasty, without division of the coracoacromial ligament or resection of the acromion. Both groups experienced the same post-operative rehabilitation protocol. Wound healing and active and passive range of motion were assessed and recorded at six to eight weeks post-operatively. Subsequent post-operative visits occurred at three, six, twelve, eighteen and twenty-four months and included documentation of patient range of motion, patient derived WORC scores (1) and complete ASES scores. Preliminary results suggest, based on a one-tailed t-test, patients that receive a rotator cuff repair with acromioplasty demonstrate a statistically significant improvement (< 0.05) in Quality of Life, based on WORC and ASES scores, compared to the non-acromioplasty group. To date, three patients in the non-acromioplasty group required a revision surgery; two of these patients had a Type III acromion. Arthroscopic rotator cuff repair with arthroscopic acromioplasty in the treatment of full thickness rotator cuff tears is recommended for patients with a Type III acromion

Scapular spine fracture is a serious complication of reverse total shoulder arthroplasty (RTSA) often caused by a fall on an outstretched arm or a forced movement to the shoulder. The incidence of scapular fractures occurring after RTSA is reported between 5.8% and 10.2%. These fractures have been classified into 3 discrete fracture patterns. Avulsion of the anterior acromion (Type I), Acromion fractures (Type II) and Scapular spine fractures (Type III). This discussion will review the incidence of these post-operative peri-prosthetic fractures of the scapula after reverse TSA and describe potential treatment options and prevention methods to avoid this complication

Purpose: Preoperative morphology must be carefully assessed for proper surgical planning for patients with arthroplasty with massive rotator cuff tears, but many morphological aspects are poorly understood. The purpose of this study was to assess the technical implications of this situation. Material and methods: We included patients with arthropathy with massive rotator cuff tears who had a complete clinical and radiographic preoperative work-up. We analysed the morphological aspects of the acromion, the humerus and the glenoid cavity. Results: One hundred forty-two patients (148 shoulders) were included. The acromion presented a fracture or lysis in 13 shoulders and was thinned or had an imprint in 37. It was normal in 70 and hypertrophic in 16. The humerus showed signs of necrosis in 31 shoulders, with a washed out trochiter in 7. Glenoid wear was classed in four stages: E0 or normal glenoid (n=51), E1 or centred wear (n=32), E2 or biconcave aspect (n=46), and E3 or major wear with superior concavity (n=13). Inverted prostheses were implanted in 80 shoulders and non-constrained prostheses in 68. The non-constrained prostheses exhibited progressive ascension of the humeral head in 63% with wear of the glenoid vault. Clinical deterioration led to revision in two patients. The non-constrained prostheses inserted in patients with an E2 glenoid had a significantly lower Constant score (p< 0.05) than the others. A notch appeared in the scapular column in 65%; of the constrained prostheses. This notch was favoured significantly in glenoids classed E2 or E3 preoperatively. The preoperative aspect of the humerus did not appear to affect clinical and radiographic outcome. Discussion: A thin or lysed acromion associated with an E2 glenoid constitutes a poor indication for non-constrained prosthesis. In this situation, an inverted prosthesis should be used taking care to avoid orienting the glenosphere upwardly, a technically difficult task. Good indications for non-contrained prostheses should probably be limited to shoulders with a normal or thickened acromion and and E1 glenoid

Background. Locked anterior shoulders (LAS) with static instability and anterior glenoid bone loss are challenging in the elderly population. Reverse shoulder arthroplasty (RSA) has been employed in treating these patients. No study has compared RSA for LAS to classically indicated RSA. Methods. A case-control study of patients treated with RSA for LAS with glenoid bone loss and static instability was performed using matched controls treated with primary RSA for classic indications. Twenty-four cases and 48 controls were evaluated. Average follow-up was 25.5 months and median age was 76. Motion, outcome assessments, and postoperative radiographs were compared. Results. Preoperatively, LAS had significantly less rotation and lower baseline outcome scores. Glenoid bone grafting was more common (p=0.05) in control group (26%) than LAS group (6.3%). Larger glenospheres were utilized more often (p=0.001) in LAS group (75%) than control group (29%). Both groups demonstrated significant improvements in pain, function, and outcome scores. Postoperatively, control group had significantly better elevation and functional outcome scores. With the exception of flexion and SST, effectiveness of treatment was similar between groups. Postoperative acromion stress fractures were seen in 21% of LAS and 9% of control (p=0.023) with a predominance of type 3 fractures in LAS. Two LAS patients remained dislocated. Conclusion. Treatment with RSA for LAS may anticipate improvements in pain and function using larger glenospheres often without the need for glenoid bone grafting. Worse postoperative motion, function, and a higher incidence of acromion stress fracture may be expected

Critical shoulder angle (CSA), lateral acromial angle (LAA), and acromion index (AI) are common radiologic parameters used to distinguish between patients with rotator cuff tears (RCT) and those with an intact rotator cuff. This study aims to assess the predictive power of these parameters in degenerative RCT. This retrospective study included data from 92 patients who were divided into two groups: the RCT group, which included 47 patients with degenerative full-thickness supraspinatus tendon tears, and a control group of 45 subjects without tears. CSA, AI, and LAA measurements from standardized true anteroposterior radiographs were independently derived and analyzed by two orthopedic surgeons. Receiver operating characteristic (ROC) analyses were performed to determine the cutoff values. No significant differences were found between patients in the RCT and control groups in age (p = 0.079), gender (p = 0.804), or injury side (p = 0.552). Excellent inter-observer reliability was seen for CSA, LAA, and AI values. Mean CSA (38.1°) and AI (0.72) values were significantly larger in the RCT group than in the control group (34.56° and 0.67°, respectively, p < 0.001) with no significant difference between groups for LAA (RCT, 77.99° vs. control, 79.82°; p = 0.056). ROC analysis yielded an area under the curve (AUC) of 0.815 for CSA with a cutoff value of 37.95°, and CSA was found to be the strongest predictor of the presence of a RCT, followed by AI with an AUC of 0.783 and a cutoff value of 0.705. We conclude that CSA and AI may be useful predictive factors for degenerative RCT in the Turkish population

The April 2012 Shoulder & Elbow Roundup. 360 . looks at katakori in Japan, frozen shoulder, if shoulder impingement actually exists, shoulder arthroscopy and suprascapular nerve blocks, why shoulder replacements fail, the infected elbow replacement, the four-part fracture, the acromion index, and arm transplantation

The treatment of patients with arthritis of the glenohumeral joint with an associated massive irreparable cuff tear is challenging. Since these patients usually have proximal migration of the humerus, the CTA extended head allows a surface with a low coefficient of friction to articulate with the acromion. Between 2001 and 2006 a total of 48 patients with arthritis of the shoulder joint associated with a massive cuff tear, were treated with a CTA head. The indications for use being Seebauer Type 1a and 1b appearances on x-ray and active abduction of the arm to more than 60° with appropriate analgesia. Preoperatively, a Constant score and an ASES pain and function score were completed as well as standard radiological assessment. These were repeated at follow up. Paired t tests were carried out for all the variables. A Kaplan-Meier survival analysis was performed. Follow up varied between 2 and 8 years. Improvements in pain, function and all movement parameters were significant at p< 0.001. There was no change in the strength component. Survival analysis showed 94% survival at 8 years (95% CL 8%) there were 2 revisions and 5 deaths. Radiological assessment at follow up revealed no evidence of humeral stem loosening. In 5 (17%) cases however there was evidence of erosion in the surface of the acromion and in 13 (45%) erosion of the glenoid. Finally one component was also seen to have subluxed anteriorly. This head design has been in use for a number of years. To date there appears to be no reported outcome of their use. This series shows that in an appropriately selected patient a satisfactory clinical outcome can be maintained in the short to medium term. The presence of erosion of the glenoid but also the under surface of the acromion does require continuing monitoring

Treatment of massive rotator cuff tears can be challenging. Previous studies with irreparable rotator cuff tears showed good clinical results of tendon healing with the arthroscopic insertion of a protective biodegradable spacer balloon filled with saline solution between the repaired tendon and the acromion [1,2], but so far no scientific evidence has showed how the device alters pressures over the repaired tendon. This biomechanical study investigated the effects of a spacer inserted in the subacromial space on pressures over the repaired rotator cuff tendon in passive motion cycles typical for post-operative rehabilitation routines. Six human cadaveric shoulders were prepared with the humerus cut 15cm below the joint and embedded in a pot, while the scapula fixed at three points on a plate. A rotator cuff tear was simulated and repaired using a suture anchor and a Mason-Allen suture. The specimens were then mounted on a custom-made pneumatic testing rig to induce passive motion cycles of adduction-abduction (90–0°) and flexion-extension (0–40°) with constant glenohumeral and superior loads and tension is exerted on the supraspinatus tendon with weights. A pressure sensor was placed between the supraspinatus tendon and the acromion. After pressure measurements for 15 cycles of each motion type, the InSpace balloon (OrthoSpace, Inc, Israel) was inserted and the specimens tested and pressure measured again for 15 cycles. Statistically significant changes in peak pressures were then measured before and after balloon. Peak pressures were measured near 90 degrees abduction. No statistical differences were observed for internal-external rotation before and after balloon-shaped subacromial spacer was inserted. Mean pressures in abduction-adduction were significantly reduced from 121.7 ± 9.5 MPa to 51.5 ± 1.2 MPa. Peak pressures after repair were 1171.3 ± 99.5 MPa and 1749.6 ± 80.7 MPa in flexion-extension and abduction-adduction motion, respectively, and significantly decreased to 468.7 ± 16.0 MPa and 535.1 ± 27.6 MPa after spacer insertion (p<0.0001). The use of the spacer above the repaired tendon reduced peak pressures and distributed them more widely over the sensor during both abduction-adduction and flexion-extension motions and therefore can reduce the stress on the rotator cuff repair. The InSpace system may reduce the pressure on the repaired tendon, thus potentially protecting the repair. Further studies to investigate this phenomenon are warranted, in particular relating these changes to shoulder kinematics following tear repair and spacer insertion

Purpose: The purpose of this study was to investigate the relationship between knee flexion contracture and spinal alignment. Methods: Ten healthy women (mean age 62) participated in this study. Subjects were examined with posture analysis system, using twelve retro-reflective markers (placed at bilateral acromion, bilateral anterior and posterior superior iliac spine, iliaccrest, greater trochanter, lateral knee joint, lateral malleolus, lateral calcaneus, and fifth metatarsal head), five cameras and a force plate. Unilateral (only right side) knee flexion contractures were simulated by using a hard brace at 0, 15 and 30 degrees. First, relaxed standing was measured without simulation, and then the same measurement was performed with each simulation. The posture without brace was used as control. The shoulder tilting angle was defined by the height difference in right and left acromions. The pelvic tilting angle was defined by the height difference in right and left superior posterior iliac spines. The anterior-bent of the trunk was defined by the slope linked right acromion and right iliac crest. The posterior-bent of the pelvis was defined by the slope linked right superior anterior iliac spine and right superior posterior iliac spine. Knee resultant force (% body weight) was calculated by using inverse dynamics technique. Results: When contracture angle increased, the trunk was significantly tilted leftward (1.4 degrees at 30 degrees contracture), and the pelvis was significantly tilted rightward (1.8 degrees at 30 degrees contracture). In anterior-bent of the trunk, no significant difference was detected. The posterior-bent of the pelvis was significantly increased (1.5 degrees at 30 degrees contracture). The severer the right knee contracture, the smaller the right knee resultant force (41.5 at controls, 28.7 at 30 degrees contracture) and the larger the left knee resultant force (40.2 at controls, 59.9 at 30 degrees contracture). Conclusions: This study showed the influence of knee flexion contracture not only in the sagittal plane, as the previous study reported, but also in the coronal plane. Severe unilateral knee flexion contracture can cause the lumbar spine bent convexly to the contracture side. This may result in Knee-Spine Syndrome