Aims. Metal and ceramic humeral head bearing surfaces are available choices in anatomical shoulder arthroplasties. Wear studies have shown superior performance of ceramic heads, however comparison of clinical outcomes according to bearing surface in total shoulder arthroplasty (TSA) and hemiarthroplasty (HA) is limited. This study aimed to compare the rates of revision and reoperation following metal and ceramic humeral head TSA and HA using data from the National Joint Registry (NJR), which collects data from England, Wales, Northern Ireland, Isle of Man and the States of Guernsey. Methods. NJR shoulder arthroplasty records were linked to Hospital Episode Statistics and the National Mortality Register. TSA and HA performed for osteoarthritis (OA) in patients with an intact rotator cuff were included. Metal and ceramic humeral head prostheses were matched within separate TSA and HA groups using propensity scores based on 12 and 11 characteristics, respectively. The primary outcome was time to first revision and the secondary outcome was non-revision reoperation. Results. A total of 4,799 TSAs (3,578 metal, 1,221 ceramic) and 1,363 HAs (1,020 metal, 343 ceramic) were included. The rate of revision was higher for metal compared with ceramic TSA, hazard ratio (HR) 3.31 (95% confidence interval (CI) 1.67 to 6.58). At eight years, prosthesis survival for ceramic TSA was 98.7% (95% CI 97.3 to 99.4) compared with 96.4% (95% CI 95.2 to 97.3) for metal TSA. The majority of revision TSAs were for cuff insufficiency or instability/dislocation. There was no significant difference in the revision rate for ceramic compared with metal head HA (HR 1.33 (95% CI 0.76 to 2.34)). For ceramic HA, eight-year prosthetic survival was 92.8% (95% CI 86.9 to 96.1), compared with 91.6% (95% CI 89.3 to 93.5) for metal HA. The majority of revision HAs were for cuff failure. Conclusion. The rate of all-cause revision was higher following metal compared with ceramic humeral head TSA in patients with OA and an intact rotator cuff. There was no difference in the revision rate for HA according to bearing surface. Cite this article: Bone Joint J 2024;106-B(5):482–491

In a prospective study between 2000 and 2005, 22 patients with primary osteoarthritis of the shoulder had a total shoulder arthroplasty with a standard five-pegged glenoid component, 12 with non-offset humeral head and ten with offset humeral head components. Over a period of 24 months the relative movement of the glenoid component with respect to the scapula was measured using radiostereometric analysis. Nine glenoids needed reaming for erosion. There was a significant increase in rotation about all three axes with time (p < 0.001), the largest occurring about the longitudinal axis (anteversion-retroversion), with mean values of 3.8° and 1.9° for the non-offset and offset humeral head eroded subgroups, respectively. There was also a significant difference in rotation about the anteversion-retroversion axis (p = 0.01) and the varus-valgus (p < 0.001) z-axis between the two groups. The offset humeral head group reached a plateau at early follow-up with rotation about the z-axis, whereas the mean of the non-offset humeral head group at 24 months was three times greater than that of the offset group accounting for the highly significant difference between them

Hemi shoulder arthroplasty is a rather successful procedure although revision surgery due to secondary glenoid erosion is reported in more than 25%. The downside of common shoulder arthroplasty is that in a deltopectoral approach the subscapularis tendon needs to be detached for exposure of the humeral head. Refixation of subscapularis tendon is associated with a retear rate of 4%, furthermore with progressing fatty muscle infiltration and loss of function. In case of revision surgery a second subscapularis tendon detachment is even more associated with worse function. Thus, arthroscopic humeral head resurfacing is an expedient alternative for minimal invasive humeral head arthroplasty without compromising subscapularis function. The purpose of this study was to report first clinical and subjective results after arthroscopic-assisted resurfacing of the humeral head. For this prospective case series, 24 patients (7 females, 17 males; mean age 59 years, range 42–73 years) undergoing arthroscopic-assisted partial shoulder resurfacing with the partial eclipse prosthesis were included in the study. Clinical conditions and subjective assessments were evaluated before surgery and annually thereafter using the Constant score (CS), active range of motion (ROM), visual analog scale (VAS) for pain, and the American Shoulder and Elbow Surgeons scale (ASES). Radiological outcomes and major complications were monitored. The mean CS for all patients improved significantly from 51 points preoperatively to 83 points 12 months after surgery (p=0.005). Trends towards increasing ROMs were detected. Subjective scores significantly improved from baseline to the 1-year follow-up (VAS: from 6.4 to 2.5, p=0.010; ASES: from 47 to 76, p=0.026). The majority of patients (88%) stated that they would undergo the procedure again. Revisions were indicated in 17% due to progression of osteoarthritis. Arthroscopic-assisted partial humeral head resurfacing as a minimal invasive procedure with the advantages of bone stock preservation and intact subscapularis tendon allowed immediate postoperative active mobilization and provided significant improvements in subjective outcome. In case of revision surgery a primary situation was encountered with postoperative results comparable to primary arthroplasty

Introduction. Shoulder arthroplasty is used to treat several common pathologies of the shoulder, including osteoarthritis, post-traumatic arthritis, and avascular necrosis. In replacement of the humeral head, modular components allow for anatomical variations, including retroversion angle and head-neck angle. Surgical options include an anatomic cut or a guide-assisted cut at a fixed retroversion and head-neck angle, which can vary the dimensions of the cut humeral head (height, anteroposterior (AP), and superoinferior (SI) diameters) and lead to negative long term clinical results. This study measures the effect of guide-assisted osteotomies on humeral head dimensions compared to anatomic dimensions. Methods. Computed tomography (CT) scans from 20 cadaveric shoulder specimens (10 male, 10 female; 10 left) were converted to three-dimensional models using medical imaging software. An anatomic humeral head cut plane was placed at the anatomic head – neck junction of all shoulders by a fellowship trained shoulder surgeon. Cut planes were generated for each of the standard implant head-neck angles (125°, 130°, 135°, and 140°) and retroversion angles (20°, 30°, and 40°) in commercial cutting guides. Each cut plane was positioned to favour the anterior humeral head-neck junction while preserving the posterior cuff insertion. The humeral head height and diameter were measured in both the AP plane and the SI plane for the anatomic and guide-assisted osteotomy planes. Differences were compared using separate two-way repeated measures ANOVA for each dependent variable and deviations were shown using box plot and whisker diagrams. Results. Guide-assisted cuts tend to be smaller than the anatomic humeral head dimensions. Retroversion angle showed a significant effect on head height, AP, and SI diameters (p=0.002). The effect of head-neck angle was only significant for SI diameter (p<0.001). The largest dimensional deviation was observed at 20 degrees of retroversion and resulted in a 2.5mm decrease in humeral head height, averaged over the range of head-neck values. Conclusion. Where patient's natural anatomy falls outside the range of commercial cutting guides, resection according to the template may result in a deviation from the natural dimensions of the humeral head, which impacts the sizing of the implant head component. This has implications for both manufacturers to create a template that has a larger range of retroversion angles, as well as surgeons' choices in intra-operative planning

Reverse shoulder arthroplasty (RSA) has an increasing effective use in the treatment of patients with a variety of diagnoses, including rotator cuff deficiency, inflammatory arthritis, or failed shoulder prostheses. Glenoid bone loss is not uncommonly encountered in these cases due to the significant wear. Severe bone loss can compromise glenoid baseplate positioning and fixation, consequently increasing the risk for early component loosening, instability, and scapular notching. To manage severe glenoid bone deficiencies, bone grafts are commonly used. Although, many studies report outcome of bone grafting in revision RSA, the literature on humeral head autograft for glenoid bone loss in primary RSA is less robust. The purpose of this study is to evaluate the clinical and radiographic outcomes of primary RSA with humeral head autograft for glenoid bone loss at our institution. Institutional review board approval was obtained to retrospectively review the records of 22 consecutive primary RTSA surgeries in 21 patients with humeral head autograft for glenoid bone loss between January 2008 and December 2016. Five patients died during follow-up, three were unable to be contacted and one refused to participate, leaving a final study cohort of 12 patients with 13 shoulders that underwent RSA. All patients had a clinical evaluation including detailed ROM and clinical evaluation using the American Shoulder and Elbow Surgeons (ASES) Score, Constant Score, Western Ontario Osteoarthritis of the Shoulder Index (WOOS), and Short Form-12 (SF-12) questionnaires. Preoperative and postoperative plain radiographs and CT scans were assessed for component position, loosening, scapular notching, as well as graft incorporation, resorption, or collapse. There were 6 males and 6 females, with an average age of 74 ± 6.8 years. The average BMI was 31.7 ± 5.3, and the median ASA score was 3. Average follow-up was 3.4 ± 1.1 years. The average postoperative range of motion measurements for the operative arm are: flexion = 120 ± 37, abduction = 106 ± 23, external rotation = 14 ± 12, internal rotation at 90 degrees of abduction = 49 ± 7, external rotation at 90 degrees of abduction = 50 ± 28. Average functional scores are: ASES: 76.9 ± 19.2, WOOS: 456 ± 347, SF12 physical: 34.2 ± 8.2, SF12 mental: 54.1 ± 10.2, Constant Score: 64.6 ± 14. No evidence of hardware loosening or evidence of bone graft resorption were encountered. On CT, the average of pre operative B-angle was 79.3 ± 9.3 while the pre operative reverse shoulder angle was 101.4 ± 28. Glenoid retroversion average on CT was 13.3 ± 16.6. Post operative baseplate inclination average was 82 ± 7.4 while the baseplate version 7.8 ±10. The operative technique was able to achieve up to 30 degrees of inclination correction and up to 50 degrees of version correction. In conclusion, primary reverse shoulder arthroplasty with humeral head autograft for glenoid bone loss provides excellent ROM and functional outcomes at mid-term follow-up. This technique has a high rate of bone incorporation and small risk of bone resorption at mid term follow up

Introduction. Arthritis of the glenohumeral joint is usually associated with erosion and flattening of the articular surfaces. The aim of this study was to evaluate the influence of the articular flattening on the joint reaction forces and the humeral head translations during abduction and rotation. Method. Analysis was conducted with a 3D finite element model of the shoulder, including the scapula, the humerus and 6 muscles: middle, anterior and posterior deltoid, supraspinatus, subscapularis, and infraspinatus. Both the glenoid and humeral head were eroded to artificially reproduce the flattening of an arthritic joint. Two situations were studied:. 1) an intact joint with a radius of curvature of 24mm for the humeral head and 26mm for the glenoid;. 2) an eroded joint with a radius of curvature of 40mm for the humeral head and 42mm for the glenoid. Movements of external rotation (0–45°) and abduction (0–150°) were performed by muscles’ activation. Contact forces caused by muscles wrapping on bony surfaces were accounted for. Joints forces, glenohumeral contact point locations and humeral head translations were calculated for the intact and eroded joint. Results: For the eroded joint, articular forces were up to seven times higher during rotation and five times higher during abduction. For the intact joint, the glenohumeral contact point and humeral head remained centred. On the other hand, for the eroded joint, eccentric contact points with large antero-posterior and supero-inferior humeral head translations were observed. Animated views showed that this fact was clearly related to the rocking-horse effect. Conclusions: This study showed that flattening of the glenohumeral joint due to osteoarthritis increases dramatically the articular forces and humeral head translations. This phenomenon is by itself responsible for progression of the joint’s erosion and flattening and acts as a vicious cycle. It also partly explains the reduced range of motion observed clinically. Accordingly, to limit the risks of rocking-horse effect after shoulder arthroplasty, the joint’s reconstruction should restore a natural articular radius of curvature, with a centre of rotation in the middle of the humeral head

A secure taper connection in shoulder arthroplasty is mandatory to avoid loosening and fretting. This study's objective was to determine the amount of in situ force used by surgeons to seat a humeral head and to determine the disengagement force of the taper connection. The influence of 1) material type, 2) head size, and 3) surgeon on the impaction force and the fixation (pulloff force) of the sample was examined. Methods. Impaction data was collected from experienced shoulder surgeons (n=5) during a cadaver lab. Testing groups (n=5 each) were: 1) small ceramic, 2) big ceramic, 3)small metal and 4) large metal. Twenty centric, anatomic humeral heads (DJO surgical, Vista, CA, TURONTM, material: CoCrMo or BIOLOX®delta, size: 38×14mm or 54×22mm) were paired with a corresponding humeral neck (TURON™, DJO surgical, type: neutral modular, material: CoCrMo). Each taper was always used with the same humeral head throughout testing. The impaction force sequence was recorded using an instrumented impactor (Piezo sensor, model 208 C05, PCB PIEZOTRONICSINC, Depew, NY, ±1%). The surgeons impacted all samples into the cadaver using their typical pattern of hammer strikes (Figure 1). The engaged humeral head and taper were removed by hand and then disengaged using an instrumented (U93, HBM, Darmstadt, Germany, load limit: 5kN) hand-held pulloff-device. Statistics and data analysis were performed in MATLAB (2014b, Mathworks, Natick, MA, α=0.05). Two-tailed, pearson's linear correlation coefficients are reported. Group differences were determined using Kruskal Wallis test. Pair-wise comparisons were performed using a Tukey correction. Results. Extremely high and variable impaction forces were measured (Table 1, Figure 2). The maximum force was nearly 27 kN; however, that value reduced to ∼18kN when the data from an outlier surgeon was removed. Maximum impaction forces were 12.45±4.36 kN, and the average was 10.47±3.63 kN. The pulloff force ranged from 0.94 kN to 5.54 kN with an average of 2.76±1.19 kN. Higher impaction forces required higher pulloff forces to disengage the taper connection (p<0.001, R>−0.608). Ceramic humeral heads showed a 24% higher fixation strength (p=0.004) under similar engagement conditions (p=0.18) in comparison to metal components. Head size does not appear to influence either the magnitude of the impaction force surgeons use (p>0.20) nor the force needed to disengage the taper (p=0.25). The surgeon performing the insertion had a significant influence on the impaction strike timing (p<0.001), number of strikes (p<0.001), and the impaction forces (p<0.03) and the pulloff force (p<0.001). Conclusions. Impaction forces were markedly larger than those recorded for taper engagement in hip arthroplasty. The ceramic humeral component showed greater fixation strength in comparison to the metal for similar impaction forces. Pulloff forces were approximately 25% of the impaction force. Potentially, this low taper efficiency resulted from the cadaver absorbing much of the energy rather than the taper connection. The influence of the patient and the clinical situation on the taper efficiency is unknown. Variations between surgeons greatly influenced the impaction and the fixation force. Therefore, individual surgeon practices may substantially influence clinical fixation strength of tapered shoulder implants

Background. Humeral version is the twist angle of the humeral head relative to the distal humerus. Pre-operatively, it is most commonly measured referencing the transepicondylar axis, although various techniques are described in literature (Matsumura et al. 2014, Edelson 1999, Boileau et al., 2008). Accurate estimation of the version angle is important for humeral head osteotomy in preparation for shoulder arthroplasty, as deviations from native version can result in prosthesis malalignment. Most humeral head osteotomy guides instruct the surgeon to reference the ulnar axis with the elbow flexed at 90°. Average version values have been reported at 17.6° relative to the transepicondylar axis and 28.8° relative to the ulnar axis (Hernigou, Duparc, and Hernigou 2014), although it is highly variable and has been reported to range from 10° to 55° (Pearl and Volk 1999). These studies used 2D CT images; however, 2D has been shown to be unreliable for many glenohumeral measurements (Terrier 2015, Jacxsens 2015, Budge 2011). Three-dimensional (3D) modeling is now widely available and may improve the accuracy of version measurements. This study evaluated the effects of sex and measurement system on 3D version measurements made using the transepicondylar and ulnar axis methods, and additionally a flexion-extension axis commonly used in biomechanics. Methods. Computed tomography (CT) scans of 51 cadaveric shoulders (26 male, 25 female; 32 left) were converted to 3D models using medical imaging software. The ulna was reduced to 90° flexion to replicate the arm position during intra-operative version measurement. Geometry was extracted to determine landmarks and co-ordinate systems for the humeral long axis, epicondylar axis, flexion-extension axis (centered through the capitellum and trochlear groove), and ulnar long axis. An anatomic humeral head cut plane was placed at the head-neck junction of all shoulders by a fellowship trained shoulder surgeon. Retroversion was measured with custom Matlab code that analysed the humeral head cut plane relative to a reference system based on the long axis of the humerus and each elbow axis. Effects of measurement systems were analyzed using separate 1-way RM ANOVAs for males and females. Sex differences were analyzed using unpaired t-tests for each measurement system. Results. Changing the measurement reference significantly affected version (p<0.001). The ulnar axis method consistently resulted in higher measured version than either flexion-extension axis (males 9±1°, females 14±1°, p<0.001) or epicondylar axis (males 8±1°, females 12±1°, p<0.001). See Figure 1. Version in males (38±11°) was 7° greater than females (31±12°) when referencing the flexion-extension axis (p=0.048). Conclusion. Different measurement systems produce different values of version. This is important for humeral osteotomies; if version is assessed using the epicondyles pre-operatively and subsequently by the ulna intra-operatively, then the osteotomy will be approximately 10° over-retroverted. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Introduction: Restoration of original humeral head geometry in shoulder arthroplasty is a necessary requirement and may have a bearing on the longevity of the implant. Modern, adaptable, prosthetic components are believed to allow restoration of the individual’s proximal humeral anatomy, provided a precise osteotomy of the humeral head at the level of the anatomical neck is performed. The osteotomy and reconstruction of the humeral head is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head. Resection, along the mid-anterior portion of the cartilage/calcar border, is understood to create a surface that enables a prosthetic component to be mounted, retroverted and inclinated to the same degree as the original head geometry. The objective of this study was to determine the degree of variation in humeral head retroversion relative to the superior and inferior borders of the proximal humeral articular surface. Methods: Twenty-eight fresh frozen human cadaveric full arms were dissected free of soft tissue to expose the proximal humerus. The distal end of the humeral shaft was potted in PMMA and fixed rigidly in a custom–built jig. The following points and lines were identified and marked on each specimen:. the circumference of the anatomical neck;. (H) as the most superior point of the articular surface at the insertion of the supraspinatus tendon, (L) as the corresponding lowest point of the articular surface at the cartilage/calcar interface;. The medial (MC) and lateral (LC) humeral condyles were exposed and delineated with k-wires. A Microscribe 3D-X digitizer was used to digitize the points and lines. The data for each humerus were imported into Rhinoceros NURBS modelling software and graphically represented. The constructed graphical model was used to divide the articular portion of the humeral head into six equal sections in the axial plane. The retroversion angle, relative to the epicondyles, was calculated for each section. Results: A linear decrease in retroversion angle was noted from the most superior to most inferior point on the proximal humeral articular surface. The retroversion angle was greatest at the level of the insertion of the supraspinatus tendon (34.2deg +/−13.7deg) and least at the inferior cartilage/calcar interface (24.3deg +/−10.2deg). Discussion: Accurate recovery of humeral head geometry is a requirement in order to achieve good function. The variability in retroversion, as it relates to its point of measurement, may effect the accuracy of pre-operative assessment of a patient’s humeral head geometry as well as the osteotomy during shoulder arthroplasty, and, thus, may impact on joint range of motion and stability post-operatively. Further investigation is warranted

The humeral offset has a medial-lateral and anteriorposterior dimension and can be defined as the distance of the central axis of the humeral shaft and the center of rotation of the humeral head. When using a canal filling prosthetic stem, inserted in a collinear alignment with the long axis of the humeral shaft, the placement of the humeral head within the anatomic boundaries of the humeral osteotomy surface will be dictated by how closely the prosthetic stem-humeral head offsets match that of the patient’s natural anatomic offsets. Given the fact that there are several millimetres of variation in the medial-lateral and anterior-posterior humeral offsets among the normal patient population, it follows that in many cases the prosthetic offset will not precisely match that of each patient when a canal filling medullary component is properly inserted. This mismatch in the humeral offsets can result in malposition of the humeral head within the confines of the humeral osteotomy surface when using a centred Morse taper humeral head. Iannotti and Williams have studied, using the Polhemus tracking system, the biomechanical consequences and tolerances for a malpositioned humeral head using a prosthetic reconstructed human cadaver model (JOR in press). A 4 mm or greater malposition of the humeral head, particularly in an inferior or anterior direction (most common malposition) will result in a measurable decrease in range of motion, abnormal humeral kinematics and subacromial impingement. In addition, humeral head malposition (anterior and inferior) can result in impingement of the non-articular portion of the humeral component, rotator cuff or proximal humeral metaphysis on the glenoid component. This impingement can result in abnormal glenoid component wear (type 2 wear) or premature glenoid loosening. Solutions for management of humeral head malposition include: 1.) variable stem offsets (not currently available), 2.) humeral component with an eccentric Morse taper (DePuy – Global Advantage, Tomier – Aequalis, Zimmer – Bigliani/Flatow) or an equivalent design (Stryker – Anatomica), and 3.) under-sizing and shifting the humeral stem to a centred position. The last option, best for monoblock humeral components (original Neer design), requires impaction grafting or PMMA cement to stabilise the under-sized stem in the centred position. Whatever solution is used it is important, in most cases, to select a head size which matches the normal anatomy and center it within the confines of the normal humeral osteotomy surface area

Introduction. Total shoulder arthroplasty (TSA) is an effective treatment to restore shoulder function and alleviate pain in the case of glenohumeral arthritis [1]. Stress shielding, which occurs when bone stress is reduced due to the replacement of bone with a stiffer metallic implant, causes bone resorption of up to 9% of the humeral cortical thickness following TSA [2]. Shorter length stems and smaller overall geometries may reduce stress shielding [3], however the effect of humeral head backside contact with the resection plane has not yet been fully investigated on bone stress. Therefore, the purpose of this study was to quantify the effect of humeral head contact conditions on bone stresses following TSA. Methods. 3D models of eight male left cadaveric humeri (68±6 years) were generated from CT data using MIMICS. These were then virtually prepared for reconstruction by an orthopaedic surgeon to accept a short-stem humeral implant (Exactech Equinoxe® Preserve) that was optimally sized and placed centrally in the humeral canal. The humeral head was positioned in the inferior-medial position such that contact was achieved on the medial cortex, and no contact existed on the lateral cortex. Three different humeral head backside contact conditions were investigated (Figure 1); full backside contact (FULL), contact with only the inferior-medial half of the resection (INF), and contact with only the superior-lateral half of the resection (SUP). Cortical bone was assigned an elastic modulus of 20 GPa and a Poisson's ratio of 0.3. Trabecular bone was assigned varying stiffness based on CT attenuation [4]. A joint reaction force was then applied representing 45˚ and 75˚ of abduction [5]. Changes in bone stress, as well as the expected bone response based on change in strain energy density [6] was then compared between the intact and reconstructed states. Results. For cortical bone, the full backside contact altered bone stress by 28.9±5.5% compared to intact, which was significantly less than the superior (37.0±3.9%, P=0.022) and inferior (53.4±3.9%, P<0.001) backside contact conditions. Similar trends were observed for changes in trabecular bone stress relative to the intact state, where the full backside contact altered bone stress by 86.3±27.9% compared to intact, compared to the superior and inferior contact conditions, which altered bone stress by 115.2±45.0% (P=0.309) and 197.4±80.2% (P=0.024), respectively. In terms of expected bone response, both the superior and inferior contact resulted in an increase in bone volume with resorbing potential compared to the full contact (Figure 2). Discussion and Conclusions. The results of this study show that full humeral head backside contact with the humeral resection plane is preferable for short stem humeral TSA implants with the head in the inferior-medial position. As expected, the superior contact typically increased resorption potential in the medial quadrant due to the lack of load transfer, however interestingly the inferior contact increased resorption potential in both the lateral and medial quadrants. Analysis of implant micromotion showed that medial liftoff of the implant occurred, which resulted in a lack of load transfer in the most medial aspect of the resection plane. For any figures or tables, please contact the authors directly

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

Background. Partial humeral head resurfacing using a stemless implant is a bone-conserving option in treatment of focal chondral defects. We report our experience using the Arthrosurface HemiCAP® device. Methods. This is a retrospective study of patients with focal chondral defects of the humeral head, treated with partial resurfacing arthroplasty, with a minimum follow-up of 2 years. Mean patient age was 45.4 years (range 27–76). Patients were analyzed in 2 groups: those who underwent HemiCAP for an isolated humeral head defect, and those who had HemiCAP combined with biologic resurfacing of concomitant glenoid disease. Results. 39 patients met inclusion criteria, 5 of whom had concomitant biologic glenoid resurfacing. 24 of 34 shoulders (70.6%) with HemiCAP alone demonstrated functional improvement and decreased pain. Mean forward flexion showed some improvement from 131 degrees pre-operatively to 158 degrees post-operatively (p=0.004). Mean Subjective Shoulder Value improved from 35.0% to 83.6% (p< 0.001). ASES score improved from 29.8 to 77.7(p< 0.001). However, follow-up radiographs showed progression of glenoid disease in 20.6%(7 shoulders). 5 shoulders(14.7%) failed and were revised: 3 to total shoulder arthroplasty, 1 to hemiarthroplasty, and 1 patient underwent glenohumeral fusion. 5 (14.7%) had some pain at latest follow-up but were pursuing a course of conservative management. In the group with associated biologic glenoid resurfacing, all 5 patients had ongoing pain and progression of glenohumeral arthritis requiring revision or glenohumeral fusion. Conclusion. While 70% of patients with an isolated humeral head chondral defect had significant improvement in pain and function after HemiCAP, the outcomes were not superior to those published for complete humeral head resurfacing, or for stemmed prostheses. HemiCAP was not successful for patients with concomitant glenoid disease. Results for these patients were inferior to those published for total shoulder arthroplasty, and ultimately all were revised to a stemmed prosthesis or fused

Purpose: Osteochondral allograft transplantation for the treatment of osseous defects to the humeral head has recently grown in popularity. Because only a portion of the articulating surface of the humeral head is replaced, conformity of the allograft to the native surface is imperative to restore the natural geometry of the joint. To achieve proper conformity, it is essential that the curvature of the humeral head of the allograft tissue match that of the native tissue. Curvature determination is also important for shoulder replacement procedures. Curvature of the humeral head is difficult to directly measure in allograft specimens. As a result, predictive measurements, such as the maximum length of the humerus are used to predict this curvature. The purpose of this study was to investigate the value of various anthropometric measurements for predicting humeral head curvature. We hypothesized that the maximum length of the humerus would be the most predictive of humeral curvature. Method: 60 (28 female, 32 male) cadaveric humeri were obtained from the Hamann-Todd Human Osteological Collection. Specimens ranged from 20 to 35 years of age at the time of death (27.9 ± 4.5, mean ± SD). Specimens from this collection include height and weight as collected at the time of death. All specimens were scanned with a 3-dimensional laser scanner (NextEngine, Santa Monica, California, USA). This scanner has been shown to be accurate to within 0.005 inches. Linear measurements (maximum humeral length, epicondylar breadth) were made according to the recording standards for skeletal remains. Both measurements were made by choosing points on the 3-dimensional scan, rather than the traditional osteometric board. Humeral head curvature was determined by a custom computational code to fit a sphere to the articulating surface of the humerus. Data analysis was performed in Minitab (version 13, State College, PA, USA). A linear regression was performed for each predictive measurement. A stepwise linear regression with forward and backward substitution was performed for the most predictive variables from the initial linear regression. Results: The most predictive factors (R^2 > 0.5) were epicondylar breadth, height, maximum humeral length, and gender. Based on the linear regression coefficients, these four factors (all normalized) were included in a forward and backward stepwise regression (alpha to enter and remove = 0.15). The resulting equation (shown below) had an R^2 values of 0.807. Humeral Diameter = 0.894 + 0.048*(epicondylar breadth) + 0.043*height – 0.020*gender. Conclusion: Of the predicted measurements evaluated, patient height, epicondylar breadth, and gender were most correlated with humeral head curvature. Including these three factors in a linear regression model increased the R2 value to 0.807. If only a single measurement can be used to size the humeral curvature, patient height will give approximately the same accuracy as epicondylar breadth, and can more easily be obtained

The treatment of a chronic posterior dislocation of the shoulder is often determined by the size of the associated impression fracture of the humeral head. Our hypothesis was that patients with a chronic unreduced posterior dislocation of the shoulder and a defect in the humeral head involving between 25% to 50% of the articular surface, would do better if reconstructed with an allograft from the femoral head rather than treated by a non-anatomical reconstruction. We reviewed ten men and three women with a mean age of 42 years (36 to 51) at a mean follow-up of 54 months (41 to 64) who had this procedure. At follow-up, nine had no pain or restriction of activities of daily living. Their mean Constant-Murley shoulder score was 86.8 (43 to 98). No patient had symptoms of instability of the shoulder. Reconstruction of the defect in the humeral head with an allograft provides good pain relief, stability and function for patients with a locked, chronic posterior dislocation where the defect involves between 25% and 50% of the circumference of the articular surface

In shoulder arthroplasty, humeral resurfacing or short stem devices rely on the proximal humeral bone for fixation and load transfer. For resurfacing designs, the fixation takes place above the anatomical neck, whilst for short stem designs the resection is made at the anatomical neck and fixation is achieved in the bone distal to that resection. The aim of the study is to investigate the bone density in these proximal areas to provide information for implant design and guidance on appropriate positions to place implant fixation entities. CT scans of healthy humeri were used to map bone density distribution in the humeral head. CT scans were manually segmented and a solid model of the proximal humerus was discretised into 1mm tetrahedral elements. Each element centroid was then assigned an apparent bone density based on CT scan Grey values. Matlab was used to sort data in spatial groups according to element centroid position to map bone density distribution. The humeral head was divided into twenty 2mm thick slices parallel to the humeral neck starting from the most proximal region of the humeral head to distal regions beneath epiphyseal plate (Fig 1a). Each slice was then radially divided into 30 concentric circles and each circle was angularly divided into 12 regions (Fig 1b). The bone density for each of these regions was calculated by averaging density values of element centroid residing in each region. Average bone density in each slice indicates that bone density decreases from proximal region to distal regions below the epiphyseal plate and higher bone density was measured proximal to the anatomical neck of the humerus (Fig2). Figure 3 shows that, both above and below the anatomical neck, bone density increases from central to peripheral regions where eventually cortical bone occupies the space. This trend is more pronounced in regions below the anatomical neck and above the epiphyseal plate. In distal slices below the anatomical neck, a higher bone density distribution in inferior (calcar) regions was also observed. Current generation short stem designs require a resection at the anatomical neck of the humerus and a cruciform keel to fix the implant in the distal bone. In the example in Figure 3, the anatomical neck resection corresponds to the 18 mm slice, with the central cruciform keel engaging between slices 18 mm and 27 mm. The data indicates that this keel should make use of the denser bone by the calcar for fixation, suggesting a crucifix orientation as highlighted in Figure 3. The current generation of proximally fixed humeral components are less invasive than conventional long-stemmed designs, but the disadvantage is that they must achieve fixation over a smaller surface area and with a less advantageous lever arm down the shaft of the humerus. By presenting a spatial density map of the proximal humerus, the current study may help improve fixation of proximally fixed designs, with a simple modification of implant rotational orientation to make use of the denser bone in the calcar region for fixation and load transfer

Splitting fractures of the humeral head are rare; part of the humeral head dislocates and the unfractured part remains attached to the shaft. We report eight cases in young patients. In five the diagnosis was made at presentation: three had minimal internal fixation using a superior subacromial approach, one had a closed reduction and one a primary prosthetic replacement. All five patients regained excellent function with no avascular necrosis at two years. In three the injury was initially unrecognised; two developed a painless bony ankylosis and one is awaiting hemiarthroplasty. It is important to obtain the three trauma radiographic views to diagnose these unusual fractures reliably. CT delineates the configuration of the fracture. In young patients open reduction and internal fixation seems preferable to replacement of the humeral head, since we have shown that the head is potentially viable

Purpose: We aimed to provide an anatomical basis for surgical techniques in rotator cuff reinsertion. The purpose of this study was to investigate the 3-dimensional trabecular bone mineral density (BMD) in the humeral head bone and determine areas of low density. Limited information exists for humeral head to understand its mechanical behaviour. Materials and Methods: 15 unpaired fresh humeral heads were harvested and frozen. The mean age was 75 years old. All abnormal bones underlying fractures, major arthrosis or surgical interventions were excluded from the study All the heads were scanned using a three-dimensional HR-pQCT system providing 80 microns slices nominal resolution. Manually outlining of the contours of cancellous bone was done in different areas: lesser tuberosity, greater tuberosity, articular part and centre. The parameters included in the analysis were: bone volume density (BV/TV, Trabecular thickness (tb.Th)(mm), Trabecularseparation(TB.Sp)(mm), Trabecular number(TB.N. (1/mm). Results: The average density of the lesser tuberosity is the highest of the whole head (BV/TV= 0,228). The centre of the head is devoided of large trabeculae with a very low density (BV/TV =0,1). The greater tuberosity is rich in thin trabeculae (Tb Th = 0,265) separated by large spaces (1,5). The articular part presents the higher density (BV/TV =0,3). Conclusions: Emphasis has traditionally been placed on cortical bone as quality predictor due to its stiffness for achieving primary stabilisation. However screws and anchors are mainly in contact with cancellous part of bone, and mechanical characteristics of cancellous bone also influence the load-bearing capacity of implant –bone union This studies is interesting in showing areas of poor cancellous bone quality and may help to improve surgical techniques

Background: Fractures of the humeral head are a relevant problem in orthopedic surgery and the optimal therapeutic strategy of displaced fractures remains debated controversially in literature. In this respect, a special locking-plate was designed recently for the humerus to improve fixation of open reduction. However, analysis of larger series are still missing. Hence, the aim of this study was to analyze prospectively all patients suffering from humeral head fractures which were stabilized by the internal fixation system PHILOS (Synthes). Patients and Methods: From 01/2002 until 08/2005 225 displaced humeral head fractures were treated by PHILOS plates. The fractures were classified according to the classification of Neer. Mean observation period was 9 months postoperative. For clinical evaluation the constant score was calculated after a mean observation period of 9 months. Moreover, an X-ray was performed in two plains to judge the implant position. From the total collective of 225 patients, an amount of 176 patients were enclosed into the clinical evaluation. The others were either deceased, or could not be contacted for other reasons. Results: Out of the enrolled 176 patients into the follow-up study, 35% were Neer III, 43% were Neer type IV/V-3, and Neer type IV/V-4 were found in 12% beside 10% others. After 9 months, the mean constant score was absolute 75 ± 17 points. In direct postoperative X-ray of the 225 patients, a correct reduction and adequate axis between head and shaft was found in 92% of the patients. However, in 14% incorrect implant position was present in terms of intraarticular screws (11%) and elevated plate position in 6 cases. Moreover, after 9 months 8 patients demonstrated secondary implant dislocation, 3 of the head and 5 of the shaft and 14% suffered from secondary screw perforation into the joint due to humeral head sintering. Complete necrosis of the humeral head was present in 5 cases whereas partial necrosis was proven in 9 patients. Since sometimes, several complications were present in a single patient, the total amount of complication cases was 29 and these patients required secondary surgery. Conclusion: The PHILOS locking plate system allows for an reliable internal fixation of humeral head fractures presenting a reasonable low complication rate. However, surgical pearls comprise mandatory cerclages of both tubercula framed onto the plate and correct axis of humeral head reposition. Typical pitfalls are intraarticular screws, secondary sintering and mislead anticipation of the stronghold of screw fixation in the bone by the locking mechanism. An randomized prospective study is currently on the way to further illuminate the quality of locking plate systems in the humeral head

Shoulder arthroplasty is used to treat osteoarthritis, post-traumatic arthritis, and avascular necrosis. Modular components allow for natural variability in shoulder anatomy, including retroversion and head-neck angles. Surgical options include anatomic or guide-assisted cut at a fixed retroversion and head-neck angle. The purpose of this study was to determine the variability between head height (HH) and anteroposterior (AP) and superoinferior (SI) diameters using anatomic and guide-assisted humeral head cuts. Computed tomography scans of 10 cadaveric shoulder specimens (5 male, 5 female) were converted to 3D models. An anatomic humeral head cut plane was placed at the anatomic head–neck junction maintaining the posterior cuff insertion for all shoulders by a fellowship trained shoulder surgeon. Cut planes were generated for standard implant head neck angles (125°,130°,135°, and 140°) and retroversion angles (20°,30°, and 40°) in commercial cutting guides, for a combination of 12 repeated cut conditions per specimen. The humeral HH and the head diameter were measured in the AP and the SI planes for anatomic and guide-assisted osteotomy planes. Differences were compared using a separate two-way repeated measures ANOVA for each dependent variable. Guide-assisted cuts showed no significant effect on HH due to head-neck (p=0.205) or retroversion angles (p=0.190). These results persisted by gender (male: head-neck p=0.659 and retroversion p=0.386; female: head-neck p=0.204 and retroversion p=0.190). SI diameter increased by 1.3 mm with increasing head-neck angle (p<0.001), but there was no effect due to retroversion (p=0.148). A head-neck angle of 125° caused the greatest decrease in SI diameter of −2.8 mm compared to the anatomic cut, averaged over the retroversion range. The greatest reduction of SI diameter, −3.4 mm compared to anatomic, occurred with 125° head-neck angle and 20° retroversion. By gender, males showed a significant effect from head-neck angle (p=0.008), but females did not (p=0.077). There was no significant difference from retroversion in either gender group (male p=0.792; female p=0.057). There was no significant difference in AP diameter by head-neck (p=0.192) or retroversion angles (p=0.168). These results persisted in the males (head-neck p=0.420 and retroversion p=0.780). In females, there was no effect from head-neck angle (p=0.232); however, retroversion angle trended toward significance (p=0.050). For patients whose natural anatomy falls outside the range of the commercial cut guides, templated resection may result in deviation from natural humeral head dimensions. Due to the large variability in anatomic retroversion and head-neck angles in the subjects of this study, further study with a larger sample size is needed to investigate observed trends. These preliminary results have implications for manufacturers to create guides to represent a larger segment of the population, and surgeons' intra-operative choice