The shape of the glenoid can vary between pear and oval, depending on the presence of a glenoid notch. We measured the glenoid notch angle (the angle between the superior and inferior part of the anterior glenoid rim) in 53 embalmed cadavers and investigated its relationship with the labral attachment to the glenoid at that point. The attachment of the anterosuperior labrum at the site of the glenoid notch was classified as tight or loose or, in some cases, there was a sublabral foramen. The anterior labrum was then removed and digital images perpendicular to the glenoid notch were taken. Using a digital image analysis program, the angle of the glenoid notch was measured. In 37 shoulders (70%) the attachment of the labrum at the site of the glenoid notch was assessed as tight and in eight (15%) as loose. In eight shoulders (15%) a sublabral foramen was found. The mean glenoid notch angle was 153° in the loosely attached group, 159° in the sublabral foramen group and 168° in the group with a tight attachment. The presence of a glenoid notch was noted only when the glenoid notch angle was less than 170°. The glenoid notch angle is related to the attachment of the labrum. In the presence of a glenoid notch, there is more likely to be a loosely attached labrum or sublabral foramen. The loose attachment of the anterosuperior labrum may be a predisposing factor in traumatic anterior instability

Aims. Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. Methods. 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane. Results. Edge-wear was found predominantly along the superior acetabular edge in all cases, while its median location was 8° (interquartile range (IQR) -59° to 25°) within the anterosuperior quadrant. The deepest point of these scars had a median location of 16° (IQR -58° to 26°), which was statistically comparable to their centres (p = 0.496). Edge-wear was in closer proximity to the superior apex of the cups with greater angles of acetabular inclination, while a greater degree of anteversion influenced a more anteriorly centred scar. Conclusion. The anterosuperior location of edge-wear was comparable to the degradation patterns observed in acetabular cartilage, supporting previous findings that hip joint forces are directed anteriorly during a greater portion of walking gait. The further application of this novel method could improve the current definition of optimal and safe acetabular component positioning. Cite this article: Bone Joint Res 2021;10(10):639–649

Abstract. OBJECTIVES. Although surgical periacetabular osteotomy (PAO) for hip dysplasia aims to optimise acetabular coverage and restore hip function, it is unclear how surgery affects capsular mechanics and joint stability. The purpose was to examine how the reoriented acetabular coverage affects capsular mechanics and joint stability in dysplastic hips. METHODS. Twelve cadaveric dysplastic hips (n = 12) were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°) and performed internal-external rotations and abduction-adduction to 5 Nm in each rotational or planar direction. Each hip underwent a PAO, preserving the capsule, and was retested postoperatively in the robot. Paired sample t-tests compared the range of motion before and after PAO surgery (CI = 95%). RESULTS. Pre-operatively, the dysplastic hips demonstrated large ranges of internal-external rotations and abduction-adduction motions throughout all flexion positions. Post-operatively, the PAO slackenend the anterosuperior capsule and tightened the inferior capsule. This increased external rotation in Flexion 60° and Flexion 90° (∆. ER. = +16 and +23%) but provided lateral coverage to decrease internal rotation at Flexion 90° (∆. IR. = –15%). The PAO also reduced abduction throughout, but increased adduction in Neutral 0°, Flexion 30°, and Flexion 60° (∆. ADD. = +34, +30%, +29% respectively). CONCLUSIONS. The PAO provided crucial osseous structural coverage to the femoral head, decreasing hypermobility and adverse loading at extreme hip flexion-extension. However, it also slackened the anterosuperior capsule and increased adduction and external rotation, which may lead to ischiofemoral impingement and adductor irritations. Capsular instability may be secondary to acetabular undercoverage, thus capsular alteration may be warranted for larger corrections or rotational osteotomies. To preserve native hip and delay joint degeneration, it is crucial to preserve capsule and elucidate amount of reorientation needed without causing iatrogenic instability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

While reverse shoulder arthroplasty (RSA) is a reliable treatment option for patients with rotator cuff deficiency, loss of glenoid baseplate fixation often occurs due to screw loosening. We questioned whether an analysis of the trabecular bone density distribution in the scapula would indicate more optimal sites for screw placement. As such, the purpose of this study was to determine the anatomic distribution of trabecular bone density in regions of the scapula available for screw placement in RSA. Seven cadaveric shoulders were computed tomography (CT) scanned, and then voxels of the scapulae were isolated from the CT volume (Mimics 15.0 Materialise, Leuven, Belgium). Analyses were conducted in a common, 3D coordinate system. Volumetric regions of interest (ROI) within the scapula were identified based on potential baseplate screw sites. ROIs included areas at the base of the coracoid process lateral and inferior to the suprascapular notch, in the posterior and anterior lateral spine and in the anterosuperior and posteroinferior lateral border. Hounsfield Units (HU) were extracted from voxels corresponding to trabecular bone within each ROI. Overall bone density was summarised as the frequency of HU values above 80% of the ROI's maximum density value. Paired, two-tailed t-tests assuming unequal variance were used for pairwise comparisons (P≤0.05). Intra-region analyses compared two ROIs within the same broad anatomical structure; inter-region analyses compared ROIs between anatomical structures. Areas of the spine and lateral border of the scapula appeared to be denser than the coracoid process. Intra-region comparisons indicated no significant differences within ROI: coracoid P=0.43, spine P=0.95, lateral border P=0.41. ROI inferior to the suprascapular notch were on average 3.78% (P=0.08) and 6% (P=0.04) less dense than the anterosuperior and posteroinferior lateral border and 7.59% (P=0.006) and 7.72% (P=0.01) less dense than the anterior and posterior lateral spine. ROI lateral to the suprascapular notch were 6% (P=0.05) and 8.21% (P=0.02) less dense than the anterosuperior and posteroinferior lateral border and 9.8% (P=0.006) and 9.94% (P=0.008) less dense than the anterior and posterior lateral spine. There was no significant difference between the anterior spine and anterosuperior and posteroinferior lateral border (P=0.12, P=0.58), nor between the posterior spine and anterosuperior and posteroinferior lateral border (P=0.14, P=0.57). Results from this study indicate that the spine and lateral border of the scapula contain denser trabecular bone relative to regions in the coracoid. The higher quality bone of the spine and lateral border should be favoured over the coracoid process when fixing the glenoid baseplate in RSA. Further research may support the redesign of the glenoid baseplate geometry to better integrate the anatomy of the scapula and improve implant survival

The purpose of this study is to quantify the distribution of bone density in the scapulae of patients undergoing reverse shoulder arthroplasty (RSA) to guide optimal screw placement. To achieve this aim, we compared bone density in regions around the glenoid that are targeted for screw placement, as well as bone density variations medial to lateral within the glenoid. Specimen included twelve scapula in 12 patients with a mean age of 74 years (standard deviation = 9.2 years). Each scapula underwent a computed tomography (CT) scan with a Lightspeed+ XCR 16-Slice CT scanner (General Electric, Milwaukee, USA). Three-dimensional (three-D) surface mesh models and masks of the scapulae containing three-D voxel locations along with the relative Hounsfield Units (HU) were created. Regions of interest (ROI) were selected based on their potential glenoid baseplate screw positioning in RSA surgery. These included the base of coracoid inferior and lateral to the suprascapular notch, an anterior and posterior portion of the scapular spine, and an anterosuperior and inferior portion of the lateral border. Five additional regions resembling a clock face, on the glenoid articular surface were then selected to analyze medial to lateral variations in bone density including twelve, three, six, and nine-o'clock positions as well as a central region. Analysis of Variance (ANOVA) tests were used to examine statistical differences in bone density between each region of interest (p < 0 .05). For the regional evaluation, the coracoid lateral to the suprascapular notch was significantly less dense than the inferior portion of the lateral border (mean difference = 85.6 HU, p=0.03), anterosuperior portion of the lateral border (mean difference = 82.7 HU, p=0.04), posterior spine (mean difference = 97.6 HU, p=0.007), and anterior spine (mean difference = 99.3 HU, p=0.006). For the medial to lateral evaluation, preliminary findings indicate a “U” pattern with the densest regions of bone in the glenoid most medially and most laterally with a region of less dense bone in-between. The results from this study utilizing clinical patient CT scans, showed similar results to those found in our previous cadaveric study where the coracoid region was significantly less dense than regions around the lateral scapular border and scapular spine. We also have found for medial to lateral bone density, a “U” distribution with the densest regions of bone most medially and most laterally in the glenoid, with a region of less dense bone between most medial and most lateral. Clinical applications for our results include a carefully planned trajectory when placing screws in the scapula, potentially avoiding the base of coracoid. Additionally, surgeons may choose variable screw lengths depending on the region of bone and its variation of density medial to lateral, and that screws that pass beyond the most lateral (subchondral) bone, will only achieve further purchase if they enter the denser bone more medially. We suspect that if surgeons strategically aim screw placement for the regions of higher bone density, they may be able to decrease micromotion in baseplate fixation and increase the longevity of RSA

Femoroacetabular impingement (FAI) – enlarged, aspherical femoral head deformity (cam-type) or retroversion/overcoverage of the acetabulum (pincer-type) – is a leading cause for early hip osteoarthritis. Although anteverting/reverse periacetabular osteotomy (PAO) to address FAI aims to preserve the native hip and restore joint function, it is still unclear how it affects joint mobility and stability. This in vitro cadaveric study examined the effects of surgical anteverting PAO on range of motion and capsular mechanics in hips with acetabular retroversion. Twelve cadaveric hips (n = 12, m:f = 9:3; age = 41 ± 9 years; BMI = 23 ± 4 kg/m2) were included in this study. Each hip was CT imaged and indicated acetabular retroversion (i.e., crossover sign, posterior wall sign, ischial wall sign, retroversion index > 20%, axial plane acetabular version < 15°); and showed no other abnormalities on CT data. Each hip was denuded to the bone-and-capsule and mounted onto a 6-DOF robot tester (TX90, Stäubli), equipped with a universal force-torque sensor (Omega85, ATI). The robot positioned each hip in five sagittal angles: Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°; and performed hip internal-external rotations and abduction-adduction motions to 5 Nm in each position. After the intact stage was tested, each hip underwent an anteverting PAO, anteverting the acetabulum and securing the fragment with long bone screws. The capsular ligaments were preserved during the surgery and each hip was retested postoperatively in the robot. Postoperative CT imaging confirmed that the acetabular fragment was properly positioned with adequate version and head coverage. Paired sample t-tests compared the differences in range of motion before and after PAO (CI = 95%; SPSS v.24, IBM). Preoperatively, the intact hips with acetabular retroversion demonstrated constrained internal-external rotations and abduction-adduction motions. The PAO reoriented the acetabular fragment and medialized the hip joint centre, which tightened the iliofemoral ligament and slackenend the pubofemoral ligament. Postoperatively, internal rotation increased in the deep hip flexion positions of Flexion 60° (∆IR = +7°, p = 0.001) and Flexion 90° (∆IR = +8°, p = 0.001); while also demonstrating marginal decreases in external rotation in all positions. In addition, adduction increased in the deep flexion positions of Flexion 60° (∆ADD = +11°, p = 0.002) and Flexion 90° (∆ADD = +12°, p = 0.001); but also showed marginal increases in abduction in all positions. The anteverting PAO restored anterosuperior acetabular clearance and increased internal rotation (28–33%) and adduction motions (29–31%) in deep hip flexion. Restricted movements and positive impingement tests typically experienced in these positions with acetabular retroversion are associated with clinical symptoms of FAI (i.e., FADIR). However, PAO altered capsular tensions by further tightening the anterolateral hip capsule which resulted in a limited external rotation and a stiffer and tighter hip. Capsular tightness may still be secondary to acetabular retroversion, thus capsular management may be warranted for larger corrections or rotational osteotomies. In efforts to optimize surgical management and clinical outcomes, anteverting PAO is a viable option to address FAI due to acetabular retroversion or overcoverage

Object. CT-based navigation system in total hip arthroplasty(THA) is widely used to achieve accurate implant placement. However, its internal structure was a trade secret. Therefore, it was hard to analyze optimal reference points. Now, we developed our own CT-based navigation system originally, and since then we have been conducting various analyses in order to use the system more effectively. The purpose of this study was to analyze the optimal area and the number of registration points, which enables to move initial errors into the acceptable range. Methods. We set the anterior pelvic plane(APP) as the reference plane, and defined the coordinates as follows: X-axis for external direction, Y-axis for anterior direction, and Z-axis for proximal direction. We made pelvic bone models after THA, a normal shape and acetabular dysplasia model, and performed registration using an originally developed CT based navigation system. At first, we registered point paired matching at 4 points, and surface matching was performed at 53 points, which were placed around the acetabulum. 20 points were on anterosuperior, 10 points were on posterosuperior, 20 points were on posterior around the acetabulum, and 3 points were on the pubis. We selected surface matching points based on the actual operation approach, calculated the accuracy of the error correction, and searched the optimal area and the number of surface matching points. Results. Initial error could correct under 2mm gradually more than 20 surface matching points on anterosuperior area of the acetabular, assumed anterolateral approach. Initial error correction was improved by adding the reference points on the pubis. In comparison with the initial error on the X-axis, corrections of the Y-axis and Z-axis were more difficult. Initial error could correct under 2mm with around 20 surface matching points on posterior area of the acetabulum, assumed posterior approach, initial error on the Y-axis direction had difficulty in correction similarly. The difference of the shape of the pelvic effected initial error correction, it was more difficult to correct initial error on Y, Z-axis on dysplasia hip. Discussion. To correct initial error needs more than 20 surface matching points at least on the both anterolateral and posterior approaches. However, it is hard to correct initial error depending on surface matching points on the Y-axis, so it is desirable to return to point paired matching. On the registration of anterosuperior area of the acetabulum, correction of the initial error improved effectively by adding reference points on the pubis in this study, so to get reference points on the pubis is recommended if possible. Moreover, it was hard to correct initial error on the Z-axis because reference points on the anterosuperior of the acetabulum were flat, therefore it is necessary to reduce the initial error on Z-axis, we should consider choosing other reference points such as on the iliac crests which can define Z-axis direction. When using the navigation system on pelvic, some tendencies and characteristics exist, and understanding them can make the operation smooth and precisely

Introduction. Definition-in this presentation, the discussion will not include reparable cuff deficiency, as this is handled with standard arthroplasty techniques combined with cuff repair. Factors that affect decision-making. Kinematics-fixed fulcrum or not. Bone loss. Deltoid integrity. Coracoacromial arch integrity. Age. Activity level. Options. Hemiarthroplasty. “ Extended head” hemiarthroplasty. Arthroplasty + tendon transfer. Constrained arthroplasty – currently not FDA approved in USA. Arthrodesis. Evaluation. History and physical examination. ? Prior surgery. ? Overhead function – does fixed-fulcrum kinematics exist even if the head is not centred. ? Anterosuperior instability – lack of fixedfulcrum kinematics. Cuff strength. Deltoid integrity. Radiographs – bone loss, especially glenoid. Other imaging studies not necessary. Arthroplasty. Hemiarthroplasty. Best if fixed fulcrum kinematics exists – intact CA arch, intact deltoid, at or above shoulder elevation. Technical considerations. Preserve deltoid. Preserve coracoacromial ligament, acromion. ? Preserve remaining subscapularis – make humeral cut superiorly, through the rotator cuff defect. Alternatively, take down subscapularis and capsule in one layer, mobilise and repair or transpose superiorly. Increase retroversion of humeral cut- be careful of posterior cuff (teres minor) attachment. Glenoid deficiency – especially if anterior or anterosuperior instability is present. May need to graft glenoid with head. Humeral head size-the same size or slightly larger than the one removed; avoid overstuffing. “Extended head” hemiarthroplasty (CTA head). Indications same as hemiarthroplasty. Advantages. Provides resurfacing of greater tuberosity, which is articulating with the acromion and often irregular. Potentially improves kinematics by providing a “pain free” fulcrum. Technical considerations. Difficult but not impossible to do through a superior, subscapularis sparing approach. Special jig required for cutting tuberosity. Preserve CA arch. Preserve deltoid. Increase retroversion (be careful of remaining posterior cuff attachment). Glenoid deficiency – especially if anterior or anterosuperior instability is present. May need to graft glenoid with head. Humeral head size-the same size or slightly larger than the one removed; avoid overstuffing. Hemiarthroplasty + tendon transfer. Indications. Complete subscapularis deficiency. Posterior cuff insufficiency with anterosuperior subluxation or dislocation. Techniques. Latissimus transfer – posterior cuff insufficiency. Pectoralis major transfer – subscapularis insufficiency. Deep to conjoined tendon (Resch). Superficial to conjoined tendon (Rockwood and Wirth). Combined. Constrained arthroplasty. Not FDA approved in US. Delta III – reverse prosthesis. Reasonable results with medium-term follow-up in Europe (5–10 years). Rehabilitation. Limited goals. Primary goals are pain relief and stability. Passive flexion to 90°, passive ER to 30° for 4 weeks. Advance stretches and add active range of motion and active assisted range of motion (overhead pulley) at 4 weeks. Strengthening – 6 weeks. Results. Less predictable and less functional overall than most other disease categories (e.g., OA). Average elevation in most series is 120°. Usually good pain relief except in patients with anterosuperior subluxation

The treatment of severe acetabular bone loss is challenging, especially in the setting of an associated chronic pelvic discontinuity. There are several available treatment options for chronic pelvic discontinuity, each of which has its own disadvantages. One of the major difficulties with this entity, regardless of the reconstructive technique chosen, is the inability to obtain reproducible healing of the discontinuity. We evaluated the use of acetabular distraction, a technique which achieves peripheral or lateral distraction and central or medial compression across the discontinuity. We recommend acetabular distraction to allow for implantation of a stable construct, achieve biologic fixation and increase the likelihood of discontinuity healing. In this multi-center trial, 32 patients that underwent acetabular revision for a chronic pelvic discontinuity using acetabular distraction were radiographically evaluated at a minimum of 25 months (range, 25 to 160 months). The study cohort was categorized according to the Paprosky acetabular bone loss classification: seven (22%) type IIC, five (16%) type IIIA, and 20 (62%) type IIIB defects. Fourteen (70%) of the 20 patients with a type IIIB acetabular bone loss pattern required use of augments for acetabular reconstruction. Of the 32 patients, 1 (3%) patient required a revision for aseptic loosening, 2 (6%) patients had evidence of radiographic loosening but were not revised, and 3 (9%) patients had migration of the acetabular component into a more stable position. Radiographically, 22 (69%) of the cohort demonstrated healing of the discontinuity. The Kaplan-Meier construct survivorship was 83.3% when using aseptic acetabular loosening as an end-point. During this study, the authors created a new pelvic discontinuity classification based on the type of reconstruction required. The classification mirrors the Paprosky acetabular bone loss classification. A Type I chronic pelvic discontinuity required jumbo cup reconstruction without augments. A type II discontinuity required the use of an augment for an extracavitary defect. A type III discontinuity required an augment for an intracavitary defect. Type III defects were further subdivided into type IIIA and IIIB discontinuity. Type IIIA discontinuities utilized an augment to reconstruct the anterosuperior and/or posteroinferior column defect for primary stability of the overall construct. Type IIIB discontinuities utilized augments to reconstruct the anterosuperior and/or posteroinferior column defect for primary stability as well as a posterosuperior augment for supplemental fixation. All augments were unitized to the cup with cement. Type IV defects were massive defects that required the use of two orange-slice augments, secured together with screws and placed centrally to restore the defect, and a cup implanted and unitized to the augments with cement. According to this new classification, the discontinuity reconstructions in our study were classified as follows: 12 (38%) type I, 8 (25%) type II, 6 (19%) type IIIA, 6 (19%) type IIIB, and 0 as type IV. Acetabular distraction technique demonstrates favorable radiographic outcomes with reproducible discontinuity healing in a majority of cases. This alternative technique allows for biologic fixation and intra-operative customization of the construct to be implanted based on the bone loss pattern present following component removal

In diagnosis and repair of partial subscapularis tendon tears, we used a simplified arthroscopic direct technique. We used the anterosuperior arthroscopic portal to visualise the subscapularis tendon insertion, while probing and repairing from the adjacent anterior portal. Three anatomical dissections were done to define the insertion of the subscapularis tendon at the lesser tuberosity. While viewing from the anterosuperior portal, we repaired the subscapularis tendon with one or two suture anchors, inserted into the lesser tuberosity from the anterior portal. Suture management was via the standard posterior portal. From the anterior portal, a tendon-penetrating grasping device passed the sutures through the displaced subscapularis tendon. The arthroscopic knots were tied from the anterior portal. Associated with the first 10 subscapularis repairs were six complete and four partial thickness supraspinatus/infraspinatus tears. There were no isolated subscapularis tears. Three patients had associated biceps lesions. Subscapularis tears are often associated with supraspinatus and infraspinatus tendon tears. Direct anterosuperior viewing and anterior probing enables the surgeon to see and repair ‘hidden’ tears

Objectives. Our principle is to bring the socket back to the true acetabulum position. A large structural bone graft is required for severe subluxation. We obtained good long-term results with structural bone grafts. It is necessary to evaluate the bone graft 3 dimensionally, not 2 dimensionally. M and M. We evaluated our 305 primary THAs operated from April 2010 to Mar 2014. Structural bone grafts were utilized on the acetabulum in 39 cases (12.8%). We measured the CE angle on post-operative plain coronal x-rays. 3D-CT evaluation was carried out on the cases with CE angles of 0 degrees or less. We checked the position of the graft and see how much surface area the graft occupies of the total area that receives the load. Result. Mean CE angle on the post-op plain coronal x-rays was −1.5°. 15 cases (38.5%) had 0 degree or less CE angles on the post-op plain coronal x-rays. 11 cases (−15°≤CE<0°), and 4 cases (−30°≤CE<−15°). Mean CE angle was +3.7° on coronal CT of the apex of the socket. Graft position on the acetabulum on 3D-CT was anterosuperior in 13 cases and posterosuperior in 2 cases, wile none showed wide positioning from anterosuperior to posterior. Conclusion. The contact surface area between the graft and the socket is not necessarily large 3 dimensionally, even if the CE angle is 0 degrees in the plain coronal X-rays. Depending on the graft position, sufficient support is considered to be obtained, even though a large size graft is used

Glenoid failure remains the most common mode of total shoulder arthroplasty failures. Porous tantalum metal (Trabecular Metal™, Zimmer) have grown in popularity in hip and knee arthroplasty. First-generation porous tantalum metal-backed glenoid components demonstrated metal debris, resulted in failure, and were revised to second-generation glenoid implants. Evidence for second-generation porous tantalum metal implants in shoulder arthroplasty is sparse.1–4 The purpose of this study was to assess clinical and radiographic outcomes in a series of patients with second-generation porous tantalum glenoid components at a minimum two-years postoperative. We retrospectively reviewed the clinical and radiographic outcomes of patients who received a second-generation porous tantalum glenoid component anatomic shoulder arthroplasty between May 2009 and December 2017 with minimum 24 months follow-up. The shoulder arthroplasties were performed by one of two senior fellowship-trained surgeons. We collected postoperative clinical outcome indicators: EQ5D visual analog scale (VAS), Western Ontario Osteoarthritis of the Shoulder (WOOS) Index, American Shoulder and Elbow Surgeons (ASES) Score, and Constant Score (CS). Radiographic review was performed by an independent fellowship-trained surgeon. The Endrizzi metal debris grading system1 was utilized to grade metal debris. We computed descriptive statistics and compared outcome scores between groups via the non-parametric Wilcoxon rank-sum test, with group-wise comparisons defined by: metal debris and humeral head migration (secondary analyses). Thirty-five patients [23 male (65.7%) and 12 female (34.3%)] with 40 shoulder replacements participated in the study. Forty of 61 shoulders (65.6%) had an average of 64 ± 20.3 months follow-up (range 31 to 95). Average BMI was 27.5 ± 4.4 kg/m2 (range 19.5 to 39.1). The average postoperative EQ5D VAS at final follow-up was 74.6 ± 22.5, WOOS Index 87.9 ± 16.6, ASES Score 88.3 ± 10.9, and CS 80.4 ± 13. At final follow-up, 18 of 40 shoulders (45%) had metal debris [15 of 40 (37.5%) Endrizzi grade 1 and three of 40 (7.5%) Endrizzi grade 2], and 22 of 40 shoulders (55%) did not show evidence of metal debris. There was one non-revision reoperation (open subscapularis exploration), one shoulder with anterosuperior escape, three shoulders with glenoid radiolucencies indicative of possible glenoid loosening, and nine shoulders with superior migration of the humeral head (>2mm migration at final follow-up compared to immediate postoperative). When comparing postoperative scores between patients with vs without metal debris, we found no statistically significant difference in the EQ5D VAS, WOOS Index, ASES Score and CS. On further analyses, when comparing superior migration of the humeral head and postoperative outcomes scores, we found no statistically significant difference. We report the longest published follow-up with clinical and radiographic outcomes of second-generation porous tantalum glenoid anatomic shoulder arthroplasties. In this series of patients, 45% of total shoulder arthroplasties with a second-generation porous tantalum glenoid implant had radiographic evidence of metal debris. This metal debris was not statistically associated with poorer postoperative outcomes. Further investigation and ongoing follow-up are warranted

Introduction. Subchondral insufficiency fracture of the femoral head (SIF) is a recently proposed concept. It is generally seen in elderly people, however, some young adults have also been reported to suffer from this fracture. The purpose of this study was to investigate the clinical results of a transtrochanteric anterior rotational osteotomy (ARO) performed in young adults with SIF. Methods. This study focused on young SIF cases (age range from 10 to 29 years). Five patients were diagnosed to have SIF at our institution and conservative treatment was initially performed. The symptoms resolved in 1 case while the other 4 cases showed progression of a collapse. In these 4 cases, ARO was performed, since the fractured area was located in the anterosuperior portion of the femoral head. The average age of the patients was 22 years (range, 16 to 29 years) at the time of surgery, consisting of 2 men and 2 women. Results. All cases were followed-up and the average follow-up period was 3.4 years (range, 1.8 to 6.8 years). The average preoperative Harris hip score was 67 points, which improved to an average of 93 points at the latest follow-up. Radiographically, the fractured lesion healed and no progression of a collapse was observed in any of the 4 cases. Conclusion. In the majority of SIF cases, only the anterosuperior portion of the femoral head is involved by the fracture. When considering the optimal surgical treatments for SIF, ARO may be one of the useful options, especially for the treatment of young patients

Introduction. Different classification systems for acetabular deficiencies, including AAOS and Paprosky, are commonly used. Classification of these bone defects is often performed based on Xrays or CT images. Although the amount of bone loss is rarely measured quantitatively in these images, objective and quantitative data on the degree of bone loss could facilitate correct and consistent classification. Recently, a computerized CT-based tool was presented to quantitatively asses bone loss: TrABL (Total radial Acetabular Bone Loss). This study demonstrates on an extended patient population that TrABL combined with standard classification systems provides more detailed, quantitative information on bone defects. Methods. CT scans of 30 severe acetabular defects, classified Paprosky IIIA and IIIB, were collected and analysed with TrABL. The tool automatically calculated the total amount of bone that was missing around the acetabulum, seen from the hip's original rotation centre. Six anatomical regions were defined for which the degree of bone loss was expressed: anterosuperior, anteroinferior, inferior, posteroinferior, posterosuperior and medial. Results. Statistical analysis highlighted that total bone loss was highest in the posterosuperior region (63%±27%). Bone loss was lowest inferiorly. No statistical differences were found between the anterosuperior, anteroinferior, posteroinferior, and medial regions. The majority of the defects suffered at least 25% bone loss in more than half of the regions. All defects had at least one region with the same degree of bone loss. The quantitative 3D data of TrABL provided more information compared to general classification schemes. This information has shown to be crucial during implant selection and preoperative planning for multiple clinical cases. Conclusion. Classification of acetabular bone deficiencies into existing systems can be refined by the quantitative data provided by TrABL. As a result, the ease and consistency regarding the treatment selection for particular categories of challenging defects will increase

Introduction. Bracing, a strategy employed by humans and robotic devices, can be generally described as a parallel mechanical link between the actor, the environment, and/or the workpiece that alters the mechanical impedance between the tool and workpiece in order to improve task performance. In this study we investigated the potential value of bracing in the context of bone milling to treat cam-type femoroacetabular impingement (FAI) lesions. The goal of this study was to evaluate whether a proposed bracing technique could enable a user to perform a cam resection more accurately and quickly than a currently employed arthroscopic technique. Materials/Methods. Test samples consisted of white urethane plastic reproductions of a commercially available adult proximal femur, which were laser scanned to obtain ground-truth surface information. A black cam lesion was then cast onto the surface of the femur in the anterosuperior region of the femoral neck, creating a clear visual resection boundary for the simulated osteochondroplasty. Test subjects were 4 adult males (25 +/− 3 years) with no surgical experience. Test conditions included two binary factors: (1) Braced vs. Unbraced – The braced case introduced a spherical bearing tool support mounted in the approximate anterolateral arthroscopic portal position. (2) Speed vs. Accuracy – The subject was instructed to perform the resection as quickly as possible or as accurately as possible with a moderate regard for time. Following the removal of the lesion, femurs were laser scanned to acquire the post-resection surface geometry, with accuracy being reported as RMS deviation between the pre- and post-resection scans over the anterosuperior neck region. Results. In both accuracy and speed cases, bracing tended to reduce errors (on the order of 7–14%) and task duration (on the order of 32–52%), although given the small number of subjects in this pilot study, these differences were not statistically significant. Conclusion. These results provide some encouragement that our hypothesis that bracing can improve both speed and accuracy of cam lesion resection by untrained subjects may be true. The standard deviations between subjects are high and are likely due to both the difficulty of the task and differences in experience using handheld power tools, so additional subjects would be needed to verify the trends identified here

Summary. The dGEMRIC index correlates more strongly with the pattern of radiographic joint space narrowing in hip osteoarthritis at five year follow-up than morphological measurements of the proximal femur. It therefore offers potential to refine predictive models of hip osteoarthritis progression. Introduction. Longitudinal general population studies have shown that femoroacetabular impingement increases the risk of developing hip osteoarthritis, however, morphological parameters have a low positive predictive value. Arthroscopic debridement of impingement lesions has been proposed as a potential strategy for the prevention of osteoarthritis, however, the development of such strategies requires the identification of individuals at high risk of disease progression. We investigated whether delayed Gadolinium-Enhanced MRI of Cartilage (dGEMRIC) predicts disease progression. This imaging modality is an indirect measure of cartilage glycosaminoglycan content. Patients and Methods. 34 asymptomatic individuals from a longitudinal cohort study (sibkids) were assessed at baseline with the collection of Patient Reported Outcome Measures (PROMs), anteroposterior and cross-table lateral radiographs, 3D morphological MRI, and dGEMRIC at 3T of their index hip. A dGEMRIC index was calculated as a ratio of the anterosuperior acetabular cartilage T1 relaxation time and the total femoral and acetabular cartilage T1 relaxation time. 29 individuals were followed up at 5 years for repeat assessment (average age 51 years and range 36 to 67). Radiological measurements were made by a single observer using in house Hipmorf software. Radiographic disease progression was assessed using minimum joint space width (JSW), lateral sourcil JSW, and medial sourcil JSW. These were measured on baseline and five year follow-up anteroposterior radiographs with an intra-observer ICC of 0.916. Alpha angle measurements were made by the same observer on radiographs and MRI radial slices with an intra-observer ICC of 0.926. Results. Mean minimum JSW for the cohort fell by 0.16mm over five years (p=0.024). Baseline dGEMRIC index did not correlate with change in minimum JSW (r=0.031 p=0.873). There was a moderate correlation between baseline dGEMRIC and the direction of JSW loss (change in JSW at the lateral sourcil minus change in JSW at the medial sourcil) (r=0.561 p=0.002). There was a weak correlation between the change in Non-Arthritic Hip Score and baseline dGEMRIC (r=0.256 P=0.180). Maximum alpha angle measured on baseline MRI radial slices did not correlate with change in minimum JSW and weakly correlated with the direction of JSW narrowing (r=0.273 p=0.160). Conclusion. A low dGEMRIC index indicates reduced glycosaminoglycan concentration in the anterosuperior acetabular cartilage compared with the total femoral and acetabular cartilage. This correlates with lateral JSW narrowing relative to medial JSW narrowing as osteoarthritis progresses. The dGEMRIC index correlates better with osteoarthritis progression than alpha angle measurements and offers the potential to refine a predictive model for osteoarthritis progression to aid patient selection for clinical trials

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

Purpose of the study: Although the association between femoroacetabular impingement and degenerative hip disease has been well established, there is no way to detect a subgroup of hips with radiographic signs of impingement which will progress to degeneration. In addition, the majority of publications on the topic have been conducted in populations of patients with an overtly degenerative hip, where the incidence of signs of impingement is higher. There has not been any study searching for the presence of signs of impingement in a symptom free population. For this reason, we searched for signs of femoroacetabular impingement in a general population and attempted to find correlations with degenerative hip disease. Material and method: We examined 200 computed tomography (CT) series of the pelvis performed for reason other than an orthopaedic indication. Four hundred hips were thus analysed with the Amira 4.1 3D software. We measured the classical coxometric parameters, orientation of the acetabulum, alpha angle, and presence or not of a bulge at the head-neck junction. Cartilage thickness was also mapped using a precise protocol. Cartilage thickness less than 0.25mm was considered for the purpose of this study to indicate degenerative disease. All data were processed with SPPS 17.0. Results: There were 103 men and 97 women, mean age 58 years and 59 years respectively. The mean alpha angle was 55.7. Retroversion was noted in 20% of hips and 28% exhibited an anterior bulge at the head-neck junction. The mean cartilage thickness at the anterosuperior part of the hip was 37mm. Degenerative disease was present in 28 patients (14%) whose mean cartilage thickness at the anterosuperior portion of the joint was 21 mm. There was no significant correlation between cartilage thickness and acetabular orientation, alpha angle, presence of a bulge at the head-neck junction. Only age was significantly correlated with degenerative disease r=−0.158 [p< 0.0]. Discussion: Among the parameters currently considered to be risk factors for degenerative disease of the hip joint, age alone was statistically linked with reduced cartilage thickness in our symptom-free population. This would suggest that the essential mechanism underlying degenerative disease remains to be discovered. Conclusion: Our findings suggest we should be prudent when proposing corrective surgery for femoroacetabular impingement. Such surgery should be reserved for symptomatic patients

Introduction. Conventional pre-operative planning for total hip arthroplasty mostly relies on the patient radiologic anatomy for the positioning and choice of implants. This kind of planning essentially remains a static approach since dynamic aspects such as the joint kinematics are not taken into account. Hence, clinicians are not able to fully consider the evolving behavior of the prosthetic joint that may lead to implant failures. In fact, kinematics plays an important role since some movement may create conflicts within the prosthetic joint and even provoke dislocations. The goal of our study was to assess the relationship between acetabular implant positioning variations and resultant impingements and loss of joint congruence during daily activities. In order to obtain accurate hip joint kinematics for simulation, we performed an in-vivo study using optical motion capture and magnetic resonance imaging (MRI). Methods. Motion capture and MRI was carried out on 4 healthy volunteers (mean age, 28 years). Motion from the subjects was acquired during routine (stand-to-sit, lie down) and specific activities (lace the shoes while seated, pick an object on the floor while seated or standing) known to be prone to implant dislocation and impingement. The hip joint kinematics was computed from the recorded markers trajectories using a validated optimized fitting algorithm (accuracy: translational error ≍ 0.5 mm, rotational error < 3°) which accounted for skin motion artifactsand patient-specific anatomical constraints (e.g. bone geometry reconstructed from MRI, hip joint center) (Fig. 1). 3D models of prosthetic hip joints (pelvis, proximal femur, cup, stem, head) were developed based on variations of acetabular cup's inclination (40°, 45°, 60°) and anteversion (0°, 15°, 30°) parameters, resulting in a total of 9 different implant configurations. Femoral anteversion remained fixed and determined as “neutral” with the stem being parallel to the posterior cortex of the femoral neck. Motion capture data of daily tasks were applied to all implant configurations. While visualizing the prosthetic models in motion, a collision detection algorithm was used to locate abnormal contacts between both bony and prosthetic components (Fig. 2). Moreover, femoral head translations (subluxation) were computed to evaluate the joint congruence. Results. Simulations showed collisions occurring at maximal ranges of motion in the anterosuperior part of the acetabulum. Both prosthetic and bony impingements were observed, especially while lacing shoes and lying down. The more the inclination and anteversion were important, the lower the frequency of impingements was noted (e.g. 23% at 40°/0°, 13% at 45°/15°, 5% at 60°/30°). Subluxations followed the same trend (e.g. 4.0 mm at 40°/0°, 1.5 mm at 45°/15°, 0.2 mm at 60°/30°). They occurred in a posterior direction as a consequence of impingements. Conclusion. Daily tasks could expose the prosthetic hip to subluxation and impingement located in anterosuperior position. This location could be explained by the high hip flexion required to execute the motions (≥ 95°). Considering the kinematics solely, increasing inclination and anteversion seems to decrease possible conflicts, but mechanical aspects (stress, wear) should also be considered in the definition of ideal cup positioning

Purpose: Determine the ideal form of subacromial decompression. Method: Six cadaveric shoulders with intact rotator cuffs (RTC) underwent “smooth & move (SM),” limited acromioplasty with coracoacromial ligament (CAL) preservation, and CAL resection. Glenohumeral translation was measured in four directions utilizing electromagnetic spatial sensors. Peak RTC pressure was measured during arm abduction utilizing pressure film sensors. Results: Anterosuperior translation was unchanged after SM or acromioplasty, but increased from 2mm at baseline to 4mm following CAL resection with the arm at 300 abduction (p=0.03). There were no significant changes in other directions of translation following any procedure. In neutral humeral rotation RTC pressure was unchanged after SM (p=1.00). Pressure decreased 64% after a limited acromioplasty (p=0.04), and 72% after CAL resection (p=0.03). There was a trend towards increased abduction at which peak pressure occurred following CAL resection (760 compared to 620;p=0.11) In external rotation, RTC pressure decreased 26% following SM, 52% after limited acromioplasty, and 64% after CAL resection, but values were not statistically changed (p=0.52, p=0.08, and p=0.06). Similarly, abduction angle at which peak pressure was reached increased but was statistically insignificant after SM (720; p=0.75), limited acromioplasty (750; p=0.11), and CAL resection (790; p=0.08). In internal rotation, RTC pressure decreased 32% following the SM, 59% following the limited acromioplasty, and 58% following CAL resection, but none reached statistical significance (p=0.52, p=0.26, p=0.17). Abduction angle of peak pressure was unchanged after SM (670; p=0.63) and limited acromioplasty (670; p=0.63), but increased following CAL resection (620 vs. 790; p=0.04). Conclusion: A CAL resection leads to increased anterosuperior instability. “Smooth and move” or acromioplasty can safely be performed without increasing translation. Rotator cuff pressure did not significantly decrease after SM. Rotator cuff pressure was significantly decreased to a similar degree following a limited acromioplasty or a CAL resection. A limited acromioplasty with preservation of the CAL may offer the greatest decrease in cuff pressures without the undesirable effect of increased translation. However, statistical significance was affected by high anatomic variability. Therefore, the choice between “smooth & move” and acromioplasty to decrease contact pressure is likely best to be individualized based on acromial morphology