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As of 2018, upwards of 42% of the United States adult population was considered obese based on Body Mass Index (BMI) scales. With the annual number of total joint replacements increasing, this study aimed to evaluate the impact BMI has on anatomic total shoulder arthroplasty (aTSA) outcomes.This was a retrospective analysis of 128 shoulders requiring primary aTSA. Patients were stratified into three cohorts based on their BMI at surgery: under/normal weight (BMI ≤25.0), overweight (BMI25,0 ≤30.0), and obese (BMI30.0). BMI was separately analyzed as a continuous variable. Clinical endpoints were range of motion scores, including forward elevation, external rotation, and internal rotation and patient reported outcomes, including Visual Analog Scale scores, American Shoulder and Elbow Surgeons scores, and the Simple Shoulder Test. Survivorship curves were calculated using Kaplan-Meier analysis.44, 50, and 34 patient shoulders were in the under/normal weight (U/NW), overweight, and obese cohorts respectively. The mean follow-up time was 11.4 years. The U/NW cohort had more females (73%) compared to the overweight (34%; p=0.0030) and obese (35%; p=0.0015) groups; no differences were seen in revision rates. BMI was negatively correlated with age at surgery (r = -0.19, p=0.014); it was not correlated with any of the six postoperative clinical endpoints. All three cohorts saw significant improvements in forward elevation, external rotation, internal rotation, VAS, ASES, and SST when compared preoperatively to postoperatively (p0.001). There were no significant differences between the three cohorts with respect to postoperative range of motion. Postoperative ASES scores were higher for the overweight cohort (82.6 ± 18.6) compared to both the U/NW (63.0 ± 25.1) and obese cohorts (70.5 ± 26.8) (p0.001). The overweight cohort also had higher SST (p=0.0012) postoperative scores compared to the U/NW and obese cohorts; VAS scores were comparable between groups (p=0.12). The non-obese (BMI30) group (n=94) showed 5-year, 10-year, and 15-year implant survival of 98.9%, 94.9%, and 83.9%, respectively compared to 97.1%, 93.7%, and 87.0% in the obese (BMI≥30) group (n=34). The log rank test revealed no significant difference in survival curves (p=0.82).To our knowledge, this is the longest follow-up study analyzing clinical endpoints stratified by BMI for aTSA. We saw that patients with a higher BMI required shoulder replacement at a significantly younger age. However, we also report that regardless of BMI all patients saw significant improvements in patient reported outcomes and range of motion scores postoperatively.

Background Glenoid loosening is the most common long-term complication of total shoulder arthroplasty (TSA) and frequently necessitates revision. Though arthroscopic glenoid removal is an accepted treatment option for glenoid loosening, there is a paucity of outcomes literature available. The purpose of this study was to report the long-term clinical and radiographic outcomes of arthroscopic glenoid removal for failed or loosened glenoid component in TSA. We hypothesized that arthroscopic glenoid removal would produce acceptable clinical and patient-reported outcomes while limiting the need for further revisions. Methods This was a retrospective analysis of 11 consecutive patients undergoing 12 arthroscopic glenoid removals for symptomatic glenoid loosening by a single orthopedic surgeon between March 2005 and March 2018. Indication for arthroscopic glenoid removal included symptomatic glenoid loosening with radiographic evidence of a 1-2 mm radiolucent line around the glenoid. Shoulder range of motion, functionality (American Shoulder and Elbow Surgeons, Simple Shoulder Test), and pain (visual analog scale [VAS]) were evaluated. Radiographs were assessed for glenohumeral subluxation, humeral superior migration, and glenohumeral offset following glenoid removal. Results The mean follow-up period since arthroscopic glenoid removal was 55 months (range, 20-172 months). Glenoid component removal significantly reduced forward elevation, with a mean decrease from 147 ± 13° preoperatively to 127 ± 29° postoperatively (P= .031). However, there was no significant change in external rotation (44 ± 9° vs. 43 ± 19°; P= .941) or internal rotation (L4 vs. L4; P= .768). Importantly, glenoid removal significantly decreased VAS pain scores from 7 ± 3 preoperatively to 5 ± 3 postoperatively (P= .037). Additionally, improvement in ASES approached statistical significance, increasing from 33 ± 25 preoperatively to 53 ± 28 postoperatively (P= .055). With regard to radiographic outcomes, there was no evidence of glenohumeral subluxation and humeral superior migration developed in 1 patient. However, there was significant medialization of the greater tuberosity relative to the acromion, with a mean lateral offset of 6 ± 7 mm preoperatively and −2 ± 4 mm postoperatively (P= .002). Two patients required conversion to reverse TSA for persistent pain. There were no complications. Discussion These findings suggest that arthroscopic glenoid removal for symptomatic glenoid loosening is a viable option to improve pain while limiting the need for additional reoperations and decreasing the risks associated with revision arthroplasty. However, continual follow-up to monitor medialization is recommended. Level of Evidence Level IV; Case Series; Treatment Study

Background Reverse total shoulder arthroplasty is a common treatment for patients with rotator cuff arthropathy who have failed a prior rotator cuff repair. Latissimus dorsi transfer can be performed simultaneously to reverse total shoulder arthroplasty for patients with preoperative external rotation deficiency. Current literature is limited with several studies providing functional and pain improvements at short-term follow-up; however, there is a deficit in data regarding mid-term outcomes. The purpose of this study was to evaluate the clinical and radiographic outcomes following reverse total shoulder arthroplasty with latissimus dorsi transfer with mid-term follow-up. We hypothesized significant improvement in external rotation and shoulder functionality for patients with preoperative external rotation lag. Methods We retrospectively reviewed patients who underwent reverse total shoulder arthroplasty with latissimus dorsi transfer. Preoperative and postoperative changes in range of motion were assessed. American Shoulder and Elbow Surgeon Score and the Simple Shoulder Test were used to evaluate changes in shoulder function while pain scores were assessed using the Visual Analog Scale (VAS). Radiographs were reviewed for rotator cuff arthropathy, fatty infiltration, scapular notching, baseplate loosening, and osteolysis. We reported frequency and mean ± standard deviation for categorical and continuous variables, respectively. Means were compared using the paired Student's t-test and proportions using the Chi-square test. Results Fifteen patients met the inclusion criteria. The mean age of the cohort was 71.7 ± 8.4 years (range 51.2–87.8 years) with a mean follow-up of 6.3 ± 4.1 years (range 1.0–14.5 years). Reverse total shoulder arthroplasty with latissimus dorsi transfer improved external rotation (−7 ± 21.3° to 38 ± 15.8°; p value = 0.001). There was no statistically significant difference regarding forward flexion (116.3 ± 45.4° to 133.7 ± 14.7°; p value = 0.17) and internal rotation (T12 to L2; p value = 0.57). The procedure led to an increase in American Shoulder and Elbow Surgeon Score scores (37 ± 19 to 62 ± 22; p = 0.005) and Simple Shoulder Test scores (2 ± 2 to 6 ± 3; p value = 0.001) with a significant reduction in Visual Analog Scale scores (5 ± 3 to 2 ± 3; p value = 0.022). The procedure corrected external rotation lag in 10 patients. Radiographically, rotator cuff arthropathy was found to be grade 3 in two patients, grade 4 A in four patients, grade 4B in eight patients, and grade 5 in one patient. On postoperative imaging, scapular notching was found in six patients (40%). Twelve patients had cortical humeral erosion at the site of the latissimus dorsi transfer. Only one patient experienced a shoulder-related complication which was aseptic baseplate loosening and required a revision reverse total shoulder arthroplasty with allograft. Conclusions In this study, patients undergoing reverse total shoulder arthroplasty with latissimus dorsi transfer experienced improvements in range of motion, functional scores, and pain at mid-term follow-up. The shoulder-related complication rate was low. Level of evidence: IV; Case series.

Avascular necrosis (AVN) of the humeral head is a debilitating pathology that can be managed with an array of treatments depending on disease staging. Humeral head arthroplasty for AVN has demonstrated good short-term improvements in pain and range of motion, but the published long-term outcomes data are limited. The objective of this study was to report long-term survivorship and outcomes for patients undergoing hemiarthroplasty (HA) or total shoulder arthroplasty (TSA) for the treatment of AVN of the humeral head.The practice of one fellowship-trained shoulder surgeon was queried for the surgical treatment of AVN of the humeral head via appropriate International Classification of Diseases, Ninth and Tenth Revision, codes. Sixteen shoulders that met inclusion criteria were identified. Demographics included the radiographic stage, age, sex, American Society of Anesthesiologists (ASA) score, and body mass index. The primary endpoint was survivorship of the implant. Secondary endpoints were range of motion in forward elevation, internal and external rotation, visual analog scale for pain, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score, and the Simple Shoulder Test score.Of the 16 shoulders included in the study, 10 underwent HA and 6 underwent TSA. The TSA cohort was significantly older (mean 60.5 vs. 44.2, P = .005), with a higher mean ASA score (mean 3.0 vs. 2.13, P = .02) than the HA group. The 10-year survivorship rates were 88.9% for HA and 80% for TSA with no significant difference between groups. Survivorship data were available for a mean 13.0 ± 5.6 years' follow-up in the HA group and 13.8 ± 4.8 years in the TSA group. When compared to one another, the results between HA and TSA only differed in internal rotation, which was statistically significantly improved in the TSA group compared with HA (2.3 ± 2.6 compared with -3.0 ± 5.0, P = .03).The survivorship of both TSA and HA for the treatment of AVN was at least 80% at 10 years. Secondary endpoints, such as range of motion, pain, and shoulder function, improved significantly postoperatively in each cohort and were similar between the 2 groups, except for internal rotation, which had improved significantly more in the TSA group than in HA. Both TSA and HA are viable options for the treatment of AVN, each with durable long-term survival.

Daily activities subject our tendons to accumulation of sub-rupture fatigue injury which can lead to tendon rupture. Consequently, tendinopathies account for over 30% of musculoskeletal consultations. We adopted a multidisciplinary approach to determine the role of the extracellular matrix (ECM) in the pathogenesis of tendinopathy and impaired healing of ruptured tendons. We have been investigating three main areas: (i) the pathogenesis of tendon degeneration; (ii) approaches to promoting remodeling of sub-rupture fatigue injuries; and the (iii) role of the ECM in promoting scarless tendon healing. In this Kappa Delta Young Investigator award paper, we describe the key discoveries made in each of our three research areas of focus. Briefly, we discovered that sub-rupture fatigue damage can accumulate from just one bout of fatigue loading. Furthermore, any attempt to repair the fatigue damage diminishes as the severity of induced damage increases. We have utilized exercise to develop animal models of exercise-led degeneration and exercise-led repair of sub-rupture fatigue damage injuries, wherein underlying mechanisms can be uncovered, thereby overcoming a major hurdle to development of therapeutics. Since damage accumulation ultimately leads to rupture that is characterized by formation of a mechanically inferior scar, we have used the MRL/MpJ mouse to evaluate the role of the systemic environment and the local tendon environment in driving regeneration to identify new therapeutic pathways to promote scarless healing. Our data suggests that the therapeutic potential of the MRL/MpJ provisional ECM should be further explored as it may harness biological and structural mechanisms to promote scarless healing. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3115-3124, 2018.

The choice of cemented versus uncemented glenoid component fixation has generated controversy, but the evidence favors cement. Studies have shown survivorship of cemented all-polyethylene glenoid components of 95% at 10 years and still over 90% at 15 years. Virtually all glenoid with stiff metal backing, especially those that snap-fit to assemble, have had poor results even at early follow-up. Recent designs with either all-polyethylene cementless fixation or using a less-stiff, integrated tantalum backing have promising early results.

After total shoulder replacement, there is a risk of poor function of the subscapularis, which may subsequently affect clinical outcomes. A number of direct repair techniques have been described in order to restore good subscapularis function after surgery. Repair using a lesser tuberosity osteotomy instead of a tenotomy has been shown to be effective.

Background: Pectoralis major ruptures are increasing in incidence primarily due to an increase in awareness, activity level among young males between 20 and 40 years of age, and use of anabolic steroids. Although the majority of pectoralis major ruptures are acute injuries, many chronic ruptures are unrecognized and it is imperative to understand the proper evaluation of these injuries, as well as the appropriate treatment for acute and chronic ruptures.Purpose: Pectoralis major ruptures can lead to deformity and physical disability if left untreated. This review paper discusses both acute and chronic ruptures as well as indications for nonoperative treatment and operative treatment to give the reader the best understanding of this diagnosis and proper management.Methods: A systematic review of the literature was performed using a search of electronic databases. Search terms such as pectoralis major rupture, pectoralis major repair, pectoralis major tendon transfer, and pectoralis major nonoperative treatment were used. Case reports, systematic reviews, prospective and retrospective studies were included to provide a comprehensive review. The only exclusion criteria consisted of studies not published in English. This review article includes the anatomy and biomechanics of the pectoralis major muscle, proper evaluation of the patient, operative and nonoperative treatment of acute and chronic pectoralis major ruptures, and outcomes of the recommended treatment.Conclusion: Nonoperative treatment is indicated for patients with medical comorbidities, older age, incomplete tears, or irreparable damage. Patients treated non-operatively have been shown to lose strength, but regain full range of motion. Patients with surgery before 6 weeks reported better outcomes than patients with surgery between 6 and 8 weeks. The chronicity of the rupture (>8 weeks) increases the likelihood of reconstruction, involving the use of autografts or allografts. Patients treated with delayed repair had significantly better strength, satisfaction, and outcomes than patients with nonoperative treatment. The pectoralis tendon can also be transferred in patients with rotators cuff tears, atrophy, or significant functional limitation. Tendon transfers have been shown to have unpredictable outcomes, but overall satisfactory results.

Tendinopathies are common chronic injuries that occur when damage accumulation caused by sub-rupture fatigue loading outpaces repair. Studies have linked fatigue loading with various mechanical, structural, and biological changes associated with pathology. However, the multiscale progression of damage accumulation with respect to area, severity and the distinct contributions of strain level and number of cycles has not been fully elucidated. The objective of this study was to investigate multiscale mechanisms underlying fatigue damage accumulation and their effect on the cellular environment. Using an in situ model in rat tail tendon (RTT), fatigue loading was applied at various strains and cycle numbers to induce fatigue damage. Pre- and post- fatigue diagnostic mechanical testing, second harmonic generation (SHG) imaging, and transmission electron microscope (TEM) imaging were used to investigate extracellular and cellular damage modes at multiple scales. Fatigue loading at strains at or below 1.0% resulted in no significant changes in SHG damage area or severity and no changes in collagen fibril or cell morphology compared with controls. Fatigue loading at strains above 1.5% resulted in greater mechanical changes correlated with increased damage area measured by SHG and collagenous damage observed by TEM. Increased cycles at high strain further altered mechanical properties, increased structural damage severity (but not area), and altered TEM collagen rupture patterns. Cell morphology was similarly progressively affected with increased strain and cycle number. These damage mechanisms that may trigger degenerative changes characteristic of tendinopathy could be targeted as a part of prevention or therapy.

Revision shoulder arthroplasty using an unconstrained prosthesis can be a difficult procedure without the appropriate preoperative evaluation and planning. A thorough history including investigation into prior surgeries and, if obtainable, radiographic imaging can help elucidate the possible reasons for prosthetic failure. This information can help guide the choice of revision implant and, if needed, obtain the appropriate extraction devices and tools. In this chapter, the authors outline their current algorithm for approaching these often complex cases.

Many factors play a role in getting a successful outcome after shoulder arthroplasty such as soft-tissue tensioning, component version, and subscapularis healing. This article focuses primarily on component version in both anatomic and reverse shoulder replacement and how it relates to stability, function, and outcome.

Prevention of neurovascular injuries during approaches for shoulder arthroplasty involves general knowledge of the anatomical course of adjacent neurovascular structures and their proximity to various landmarks. This allows the surgeon to navigate about the shoulder while protecting or circumventing structures known to be at risk during a particular surgical approach. Adjunctive devices and monitoring methods can be helpful in difficult and even routine cases to minimize the incidence of nerve injuries. Most important is a thorough initial physical examination with documentation of neurovascular status, review of prior operative notes, and pursuing additional studies as deemed necessary.

Tendons are ineffective at repairing sub-rupture fatigue injuries. Accordingly, we evaluated whether an exercise protocol that we have previously found to decrease structural damage kinks in fatigue damaged tendons, leads to improvement in mechanical properties. We hypothesized that exercise that promotes repair of fatigue damage will decrease apoptosis and increase the population of myofibroblasts. Rat patellar tendons underwent in vivo fatigue loading for 500 or 7200 cycles. Animals resumed cage activity for 2-weeks, then either remained cage active or began treadmill running until sacrifice at 4- or 10-weeks post-fatigue loading. Exercise following fatigue damage increased the stiffness back towards naïve levels, decreased apoptosis and increased the population of myofibroblasts. Next, proteins associated with inhibition of apoptosis (Collagen VI) or activation of myofibroblast (pSmad 2/3, fibrillin, integrin subunits αV and α5) were evaluated. Data suggests that collagen VI may not be integral to inhibition of apoptosis in this context. Exercise increased pSmad 2/3 and fibrillin in the insertion region for the 7200-cycles group. In addition, exercise decreased integrin αV and increased integrin α5 in fatigue damaged tendons. Data suggests that a decrease in apoptosis and an increase in population of myofibroblasts may be integral to remodeling of fatigue damaged tendons.

Tendinopathy and tendon rupture are common and disabling musculoskeletal conditions. Despite the prevalence of these injuries, a limited number of investigators are conducting fundamental, basic science studies focused on understanding processes governing tendinopathies and tendon healing. Development of effective therapeutics is hindered by the lack of fundamental guiding data on the biology of tendon development, signal transduction, mechanotransduction, and basic mechanisms underlying tendon pathogenesis and healing. To propel much needed progress, the New Frontiers in Tendon Research Conference, co-sponsored by NIAMS/NIH, the Orthopaedic Research Society, and the Icahn School of Medicine at Mount Sinai, was held to promote exchange of ideas between tendon researchers and basic science experts from outside the tendon field. Discussed research areas that are underdeveloped and represent major hurdles to the progress of the field will be presented in this review. To address some of these outstanding questions, conference discussions and breakout sessions focused on six topic areas (Cell Biology and Mechanics, Functional Extracellular Matrix, Development, Mechano-biology, Scarless Healing, and Mechanisms of Injury and Repair), which are reviewed in this special issue and briefly presented in this review. Review articles in this special issue summarize the progress in the field and identify essential new research directions.

Tendinopathy is a common musculoskeletal injury whose treatment is limited by ineffective therapeutic interventions. Previously we have shown that tendons ineffectively repair early sub-rupture fatigue damage. In contrast, physiological exercise has been shown to promote remodeling of healthy tendons but its utility as a therapeutic to promote repair of fatigue damaged tendons remains unknown. Therefore, the objective of this study was to assess the utility of exercise initiated 1 and 14 days after onset of fatigue damage to promote structural repair in fatigue damaged tendons. We hypothesized that exercise initiated 14 days after fatigue loading would promote remodeling as indicated by a decrease in area of collagen matrix damage, increased procollagen I and decorin, while decreasing proteins indicative of tendinopathy. Rats engaged in 6-week exercise for 30 min/day or 60 min/day starting 1 or 14 days after fatigue loading. Initiating exercise 1-day after onset of fatigue injury led to exacerbation of matrix damage, particularly at the tendon insertion. Initiating exercise 14 days after onset of fatigue injury led to remodeling of damaged regions in the midsubstance and collagen synthesis at the insertion. Physiological exercise applied after the initial biological response to injury has dampened can potentially promote remodeling of damaged tendons.

Enhanced tendon and ligament repair would have a major impact on orthopaedic surgery outcomes, resulting in reduced repair failures and repeat surgeries, more rapid return to function, and reduced health care costs. Scaffolds have been used for mechanical and biologic reinforcement of repair and regeneration with mixed results. This review summarizes efforts made using biologic and synthetic scaffolds using rotator cuff and ACL as examples of clinical applications, discusses recent advances that have shown promising clinical outcomes, and provides insight into future therapy.

With variation in glenoid design focused mainly on the backside interface of the component with the glenoid bone, keeled and pegged glenoid components have become the basis for most implants. Keeled implants offer a single, deep anchor for the component, while pegged implants offer stability with less bone removal. There is a trend in multiple studies for decreased radiolucent lines, decreased loosening, and decreased revision rates with pegged components. In-line pegs confer several advantages over out-of-line pegs. Advancements in cementing techniques and glenoid preparation have improved longevity for all types of glenoid implants.

Thorough physical examination is especially important in the diagnosis of subscapularis tears; given that many tears are missed on MRI evaluation. The belly-press test may be the best test in cases where internal rotation is limited, while the belly-off sign is very sensitive for partial subscapularis tears as long as the external rotators are intact. The internal rotation lag sign, followed by the lift-off test, is the most sensitive test for predicting complete deficiency of the subscapularis when range of motion is not limited.

Studies have shown in many disciplines that longer operative times are correlated with increased complications. Recent research has shown that increased shoulder arthroscopy procedure time is associated with adverse short-term outcomes, especially infections and overnight hospital stay. This may be because longer operating time is a proxy for surgical difficulty or complexity, but it may be that operative time is itself a causative factor. Further study is warranted to see if reducing operative times may not only reduce costs but also improve quality, improving value in both the numerator and denominator.

Background Biceps tenodesis reduces the incidence of Popeye deformity occurring with tenotomy, but pain may occur with tenodesis superior to or within the bicipital groove. Arthroscopic suprapectoral tenodesis is an attractive alternative. The purpose of this study was to establish landmarks for arthroscopic suprapectoral tenodesis and determine the appropriate fixation point to optimize muscle tension. Methods Twelve fresh cadaveric shoulders were dissected. Urethane polymer was injected into the axillary artery. The position of the anterior branch of the axillary nerve was marked. The transverse humeral ligament was split, exposing the biceps (long head of the biceps [LHB]) from its origin to the pectoralis major tendon (PMT). The intra-articular portion was released. Measurements were taken from the proximal tendon to described landmarks. Results The mean length of the intra-articular LHB was 2.53 cm (range, 1.72-3.55 cm). The mean distance from the LHB origin to the inferior lesser tuberosity (LT) was 5.58 cm (range, 4.02-6.87 cm), and that to the superior border of the PMT was 8.46 cm (range, 6.46-10.78 cm). The suprapectoral tenodesis zone (inferior LT to superior PMT) was 2.96 cm (range, 1.54-4.40 cm). In all specimens, a branch of the anterior humeral circumflex arose medial to the LHB and distal to the LT and crossed the suprapectoral zone from medial to lateral at 1.49 ± 0.42 cm proximal to the PMT, approximately at the level of the axillary nerve. The musculocutaneous nerve was on average 3.06 cm (range, 1.86-3.76 cm) from the tenodesis zone. Conclusion A branch of the anterior humeral circumflex is a reliable landmark for identifying the mid-suprapectoral zone. The distance from the proximal LHB tendon to this crossing vessel averaged 6.32 cm in female specimens and 8.28 cm in male specimens. These findings allow appropriate tensioning of the LHB during arthroscopic suprapectoral tenodesis.

Supraspinatus (SS) tendon tears are common musculoskeletal injuries whose surgical repair exhibits the highest incidence of re-tear of any tendon. Development of therapeutics for improving SS tendon healing is impaired by the lack of a model that allows biological perturbations to identify mechanisms that underlie ineffective healing. The objective of this study was to develop a mouse model of supraspinatus insertion site healing by creating a reproducible SS tendon detachment and surgical repair which can be applied to a wide array of inbred mouse strains and genetic mutants. Anatomical and structural analyses confirmed that the rotator cuff of the mouse is similar to that of human, including the presence of a coracoacromial (CA) arch and an insertion site that exhibits a fibrocartilagenous transition zone. The surgical repair was successfully conducted on seven strains of mice that are commonly used in Orthopaedic Research suggesting that the procedure can be applied to most inbred strains and genetic mutants. The quality of the repair was confirmed with histology through 14 days after surgery in two mouse strains that represent the variation in mouse strains evaluated. The developed mouse model will allow us to investigate mechanisms involved in insertion site healing.

Accumulation of damage is a leading factor in the development of tendinopathy. Apoptosis has been implicated in tendinopathy, but the biological mechanisms responsible for initiation and progression of these injuries are poorly understood. We assessed the relationship between initial induced damage and apoptotic activity 3 and 7 days after fatigue loading. We hypothesized that greater apoptotic activity (i) will be associated with greater induced damage and higher number of fatigue loading cycles, and (ii) will be higher at 7 than at 3 days after loading. Left patellar tendons were fatigue loaded for either 100 or 7,200 cycles. Diagnostic tests were applied before and after fatigue loading to determine the effect of fatigue loading on hysteresis, elongation, and loading and unloading stiffness (damage parameters). Cleaved Caspase-3 staining was used to identify and calculate the percent apoptosis in the patellar tendon. While no difference in apoptotic activity occurred between the 100 and 7,200 cycle groups, greater apoptotic activity was associated with greater induced damage. Apoptotic activity was higher at 7 than 3 days after loading. We expect that the decreasing number of healthy cells that can repair the induced damage in the tendon predispose it to further injury.

Inaccurate placement of glenoid prosthesis in shoulder arthroplasty can lead to early loosening, instability, and failure. To address difficult glenoid morphology, patient-specific instrumentation and navigation techniques have been developed. Advanced imaging data has demonstrated utility in preoperative decision making. Cadaveric studies have subsequently shown that the application of advancing imaging and navigation can lead towards increased accuracy with prosthesis placement. Clinical trials have also shown increased accuracy with navigation and advanced imaging, but data demonstrating improved long-term outcomes and decreased complication rates is not yet available. This technology continues to evolve as a method to address glenoid bone loss and abnormal morphology.

Historically, fractures of the proximal humerus not amendable to closed treatment or internal fixation have been treated with hemiarthroplasty. Clinical outcomes following hemiarthroplasty have been variable and difficult to predict. Results are often correlated with increasing age, tuberosity healing, and tuberosity position. Reverse shoulder arthroplasty has demonstrated effectiveness in elderly patients with rotator cuff arthropathy and has been increasingly employed for complex fractures in older patients. Several small trials have compared the reverse arthroplasty and hemiarthroplasty for acute fractures, and reverse shoulder arthroplasty has demonstrated more reproducible results in elderly patients.

Proximal humerus fracture treatment has evolved considerably in the recent years. Fewer hemiarthroplasties are being done than in the past. The goal of this chapter is to look for alternatives to reverse total shoulder replacement and to consider what is the best treatment for four-part proximal humerus fractures in active and healthy 65 year-old patients.

We have published that shoulder rotator cuff tear is a highly cost-effective procedure, and to continue to improve value, a goal is to contain cost while maintaining or improving outcome. To bend the cost curve, reduction in direct costs (number of suture anchors used) could be a goal, and because rotator cuff repair failures are as much biologic as they are mechanical, the effect of adding anchors to improve outcomes has an obvious limit.

The accumulation of sub-rupture tendon fatigue damage in the extracellular matrix, particularly of type I collagen fibrils, is thought to contribute to the development of tendinopathy, a chronic and degenerative pathology of tendons. Quantitative assessment of collagen fibril alignment is paramount to understanding the importance of matrix injury to cellular function and remodeling capabilities. This study presents a novel application of edge detection analysis to calculate local collagen fibril orientation in tendon. This technique incorporates damage segmentation and stratification by severity which will allow future analysis of the direct effect of matrix damage severity on the cellular and molecular response.

Background The annual number of shoulder arthroplasty procedures is continuing to increase. Specimens from shoulder arthroplasty cases are routinely sent for pathologic examination. This study sought to evaluate the clinical utility and associated costs of routine pathologic examination of tissue removed during primary shoulder arthroplasty cases and to determine cost-effectiveness of this practice. Methods This is a retrospective review of primary shoulder arthroplasty cases. Patients whose humeral head was sent for routine pathologic examination were included. Cases were determined to have concordant, discrepant, or discordant diagnoses based on preoperative/postoperative diagnosis and pathology diagnosis. Costs were estimated in 2015 U.S. dollars, and cost-effectiveness was determined by the cost per discrepant diagnosis and cost per discordant diagnosis. Results We identified 714 cases of primary shoulder arthroplasty in 646 patients who met inclusion criteria. The prevalence of concordant diagnoses was 94.1%, the prevalence of discrepant diagnoses was 5.9%, and no cases had discordant diagnoses. There were 172 cases that had biceps tendon specimens sent for pathology examination, and none led to a change in patient care. Total estimated costs were $77,309.34 in 2015 U.S. dollars. Cost per discrepant diagnosis for humeral head specimens was $1424.09, and cost per discordant diagnosis is at least $59,811.78. Discussion/Conclusion Primary shoulder arthroplasty has a high rate of concordant diagnosis. Discrepant diagnoses were 5.9% in our study, and there were no discordant diagnoses. This study showed limited clinical utility in routinely sending specimens from primary shoulder arthroplasty cases for pathology examination, and calculation using a traditional life-year value of $50,000 showed that the standard for cost-effectiveness is not met.

Isolated injuries to the teres major muscle occur in competitive sporting activities such as baseball pitching, hockey and tennis. We report a similar event of a physically fit man sustaining an isolated teres major rupture while waterskiing. Non-operative management was chosen, with pain resolution and no appreciable functional limitations at follow up. Because teres major muscle injury was suspected at the time of imaging, we present a dedicated imaging protocol to optimize assessment for teres major injury.

Glenoid component loosening is one of the most common complications of total shoulder arthroplasty. It accounts for poor functional outcome, persistent pain, and increased chance of reoperation. Many factors contribute to this phenomenon, including limited glenoid bone, especially in the setting of erosion characteristic of osteoarthritis and inflammatory arthropathies, and joint-reactive forces inherent to the shoulder joint. A great deal of research has been done in the areas of component design and implantation technique. We advocate careful glenoid preparation and pressurized cementing technique of all-polyethylene pegged or keeled glenoid components with specialized instrumentation in the majority of cases. We have narrower indications for newer, ingrowth tantalum components.

We report the use of a 15° face-changing cementless acetabular component in patients undergoing total hip replacement for osteoarthritis secondary to developmental dysplasia of the hip. The rationale behind its design and the surgical technique used for its implantation are described. It is distinctly different from a standard cementless hemispherical component as it is designed to position the bearing surface at the optimal angle of inclination, that is, < 45°, while maximising the cover of the component by host bone.

Accumulation of sub-rupture fatigue damage has been implicated in the development of tendinopathy. We previously developed an in vivo model of damage accumulation using the rat patellar tendon. Our model allows us to control the input loading parameters to induce fatigue damage in the tendon. Despite this precise control, the resulting induced damage could vary among animals because of differences in size or strength among their patellar tendons. In this study, we used number of applied cycles and initial (day-0) parameters that are indicative of induced damage to assess the molecular response 7 days after fatigue loading. We hypothesized that day-0 hysteresis, elongation, and stiffness of the loading and unloading load-displacement curves would be predictive of the 7-day molecular response. Results showed correlations between the 7-day molecular response and both day-0 elongation and unloading stiffness. Additionally, loading resulted in upregulation of several extracellular matrix genes that suggest adaptation; however, several of these genes (Col-I, -XII, MMP 2, and TIMP 3) shut down after a high level of damage was induced. We showed that evaluating the 7-day molecular profile in light of day-0 elongation provides important insight that is lost from comparing number of fatigue loading cycles only. Our data showed that loading generally results in an adaptive response. However, the tendon's ability to effectively respond deteriorates as greater damage is induced.

The purpose of this study was to develop and validate an in vivo mouse model of tendon fatigue and use this model to investigate and quantify the physical manifestations of fatigue damage in mouse tendon. Patellar tendons of C57BL/6J mice were fatigue loaded at 2 Hz to three endpoints (4 N peak force per cycle for 1 h, 6 N for 1 h, and 4 N for 2 h), during which hysteresis, tangent stiffness, and peak strain of each cycle were measured. Damage accumulation was then quantified using in situ histology, and each tendon was loaded monotonically to failure. Histological damage increased significantly in all three groups (≥2-fold), and monotonic stiffness decreased significantly in the 6 N, 1 h and 4 N, 2-h groups (~25%), suggesting that damage initially manifests as changes to the collagen structure of the tendon and subsequently as changes to the function. For the fatigue loading protocols used in this study, none of the evaluated real-time parameters from fatigue loading correlated with damage area fraction measured structural damage or monotonic stiffness, suggesting that they are not suited to serve as proxies for damage accumulation. In future studies, this model will be used to compare the biological response of mouse tendon to fatigue damage across genetic strains.

Subacromial impingement syndrome (SIS) represents a spectrum of pathology ranging from subacromial bursitis to rotator cuff tendinopathy and full-thickness rotator cuff tears. The relationship between subacromial impingement and rotator cuff disease in the etiology of rotator cuff injury is a matter of debate. Both extrinsic compression and intrinsic degeneration may play a role. Management includes physical therapy, injections, and, for some patients, surgery. There remains a need for high-quality studies of the pathology, etiology, and management of SIS.