Neuromuscular electrical stimulation of humeral adductors in subjects with rotator cuff tear.

INTRODUCTION: In symptomatic patients with rotator cuff tear, MRI and radiographic studies have ascribed the pain symptom to insufficient humeral head depression during arm elevations. The arm adductors such as the teres major and pectoralis major may contribute to depression of the humerus head during arm elevations. Researchers have demonstrated that neuromuscular electrical stimulation (NMES) of the serratus anterior and lower trapezius can control scapular motions and improve acromiohumeral distance. It is unknown, however, if adductor neuromuscular training could help patients with rotator cuff tear. MATERIALS AND METHODS: A cross-sectional study of NMES of the teres major and pectoralis major was conducted on 30 symptomatic subjects with rotator cuff tear. We measured the acromiohumeral distance by ultrasonography and scapular kinematics during arm elevation with a three-dimensional motion tracking system. RESULTS: The acromiohumeral distance significantly increased during NMES of the teres major (0.73 mm, p < 0.001). However, the distance significantly decreased with NMES of the pectoralis major (0.78 mm, p < 0.001). Additionally, scapular upward rotation was greater during NMES of the teres major than during NMES of the pectoralis major (3.4°, p < 0.001). Scapular external rotation decreased significantly more during NMES of the pectoralis major than during NMES of the teres major (1.6°, p = 0.003). CONCLUSIONS: NMES of the teres major can increase acromiohumeral distance and scapular upward rotation during arm elevation. However, the decreased upward and external rotation of the scapula during arm elevation with NMES of the pectoralis major may be associated with subacromial impingement.

Personalized endoprostheses for the proximal humerus and scapulohumeral joint in dogs: Biomechanical study of the muscles' contributions during locomotion.

Osteosarcoma represents one of the most common bone tumours in dogs. It commonly occurs in the proximal humerus, the most affected anatomic site. Until recently, amputation or limb-sparing surgery leading to an arthrodesis coupled with chemotherapy were the only available treatments, but they often lead to complications, reduced mobility and highly impact dog's quality of life. Prototypes of both articulated and monobloc (no mobility) patient-specific endoprostheses have been designed to spare the limb afflicted with osteosarcoma of the proximal humerus. This study focuses on the biomechanical effects of endoprostheses and shoulder muscle kinematics. For each of the endoprosthesis designs, a minimal number of muscles needed to ensure stability and a certain degree of joint movement during walking is sought. A quasi-static study based on an optimization method, the minimization of the sum of maximal muscle stresses, was carried out to assess the contribution of each muscle to the shoulder function. The identification of the most important muscles and their impact on the kinematics of the prosthetic joint lead to an improvement of the endoprosthesis design relevance and implantation feasibility.

Modified Closed Reduction and Percutaneous Kirschner Wires Internal Fixation for Treatment of Supracondylar Humerus Fractures in Children.

OBJECTIVE: Supracondylar humerus fractures are the most frequent fractures of the paediatric elbow. The present study introduced a modified surgical procedure for treatment of supracondylar humerus fractures in children. METHODS: From February 2015 to August 2019, 73 patients with Gartland's type II and III supracondylar fractures were treated with this modified method. Totally, 68 of all patients were followed up for 3-12 months (mean 8.25 months). The evaluation results included fracture nonunion, ulnar nerve injury, pin track infection, carrying angle and elbow joint Flynn score. RESULTS: The results showed that bone union was observed in all children, one case had an iatrogenic ulnar nerve injury, and the symptoms were completely relieved in 4 months after removing of the medial-side pin. All children had no cubitus varus deformity and no pin track infection, and the rate of satisfactory results according to Flynn's criteria score was 100%. CONCLUSION: The modified closed reduction and Kirschner wires internal fixation could effectively reduce the rate of open reduction, the risk of iatrogenic ulnar nerve injury, and the incidence of cubitus varus deformity in treatment of supracondylar humerus fractures in children.

Location of the radial nerve along the humeral shaft between the prone and lateral decubitus positions at different elbow positions.

Identification of the radial nerve is important during the posterior approach to a humerus fracture. During this procedure, the patient can be placed in the prone or lateral decubitus position depending on the surgeon's preference. The distance from the radial nerve to the osseous structures will be different in each position. The purpose of this study was to identify the safety zones in various patient and elbow flexion positions. The distances from the olecranon to the center of the radial groove and intermuscular septum and lateral epicondyle to the lateral intermuscular septum were measured using a digital Vernier caliper. The measurements were performed with cadavers in the lateral decubitus and prone positions at different elbow flexion angles. The distance from where the radial nerve crossed the posterior aspect of the humerus measured from the upper part of the olecranon to the center of the radial nerve in both positions at different elbow flexion angles varied from a mean maximum distance of 130.00 mm with the elbow in full extension in the prone position to a minimum distance of 121.01 mm with the elbow in flexion at 120° in the lateral decubitus position. The mean distance of the radial nerve from the upper olecranon to the lateral intermuscular septum varied from 107.13 to 102.22 mm. The distance from the lateral epicondyle to the lateral edge of the radial nerve varied from 119.92 to 125.38 mm. There was not significant contrast in the position of the radial nerve with osseous landmarks concerning different degrees of flexion, except for 120°, which is not significant, as this flexion angle is rarely used.

Rhizomelia and Impaired Linear Growth in a Girl with Juvenile Paget Disease: The Natural History of the Condition.

In ultra-rare bone diseases, information on growth during childhood is sparse. Juvenile Paget disease (JPD) is an ultra-rare disease, characterized by loss of function of osteoprotegerin (OPG). OPG inhibits osteoclast activation via the receptor activator of nuclear factor-κB (RANK) pathway. In JPD, overactive osteoclasts result in inflammatory-like bone disease due to grossly elevated bone resorption. Knowledge on the natural history of JPD, including final height and growth, is limited. Most affected children receive long-term antiresorptive treatment, mostly with bisphosphonates, to contain bone resorption, which may affect growth. In this study, we report the follow-up of height, growth velocity, and skeletal maturation in a 16-year-old female patient with JPD. The patient was treated with cyclic doses of pamidronate starting at 2.5 years of age and with 2 doses of denosumab at the age of 8 years, when pamidronate was paused. In the following years, a sustainable decline in a height z-score and a stunted pubertal growth spurt; despite appropriate maturation of the epiphyseal plates of the left hand, the proximal right humerus and both femora were observed. Whether this reflects the growth pattern in JPD or might be associated to the antiresorptive treatments is unclear, since there is very limited information available on the effect of bisphosphonates and denosumab on growth and the growth plate in pediatric patients. Studies are needed to understand the natural history of an ultra-rare bone disease and to assess the effects of antiresorptive treatment on the growing skeleton.

Humeral elevation workspace during daily life of adults with spinal cord injury who use a manual wheelchair compared to age and sex matched able-bodied controls.

Shoulder pain and pathology are extremely common for individuals with spinal cord injuries (SCI) who use manual wheelchairs (MWC). Although risky humeral kinematics have been measured during wheelchair-based activities performed in the lab, little is known about arm kinematics in the free-living environment. The purpose of this study was to measure the humeral elevation workspace throughout a typical day for individuals with SCI who use a MWC and matched able-bodied controls. Thirty-four individuals with SCI who use a MWC (42.7±12.7 years of age, 28 males/6 females, C6-L1) and 34 age-and sex-matched controls were enrolled. Participants wore three inertial measurement units (IMU) on their upper arms and torso for one to two days. Humeral elevation angles were estimated and the percentage of time individuals spent in five elevation bins (0-30°, 30-60°, 60-90°, 90-120°, and 120-180°) were calculated. For both arms, the SCI cohort spent a significantly lower percentage of the day in 0-30° of humeral elevation (Dominant: SCI = 15.7±12.6%, Control = 32.1±15.6%, p<0.0001; Non-Dominant: SCI = 21.9±17.8%, Control = 34.3±15.5%, p = 0.001) and a significantly higher percentage of time in elevations associated with tendon compression (30-60° of humeral elevation, Dominant: SCI = 62.8±14.4%, Control = 49.9.1±13.0%, p<0.0001; Non-Dominant: SCI = 58.8±14.9%, Control = 48.3±13.6%, p = 0.003) than controls. The increased percentage of time individuals with SCI spent in elevations associated with tendon compression may contribute to increased shoulder pathology. Characterizing the humeral elevation workspace utilized throughout a typical day may help in understanding the increased prevalence of shoulder pain and pathology in individuals with SCI who use MWCs.

All-suture anchor pullout results in decreased bone damage and depends on cortical thickness.

PURPOSE: To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness. METHODS: Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified. RESULTS: The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm3 vs. 212 mm3; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle. CONCLUSION: In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.

Humeral shaft fracture and radial nerve palsy in Korean soldiers: focus on arm wrestling related injury.

INTRODUCTION: Humeral shaft fractures can lead to radial nerve injury and may require surgery and rehabilitation. We determined the causative events of humeral fracture, including arm wrestling, in young Korean soldiers and examined whether humeral fracture is related to demographic characteristics and the presence of radial nerve palsy. METHODS: We reviewed 7.5 years (July 2012 to June 2019) of medical records covering patients who had experienced a humeral shaft fracture after entering military service and had received surgery for open reduction and internal fixation. Data were obtained on basic demographics, initial event provoking the fracture, presence of radial nerve palsy, initial and follow-up severity of the weakness, and any discharge from military service because of prolonged radial nerve palsy. RESULTS: Of 123 cases, arm wrestling was the leading cause (52.8%). A high energy injury, such as falling from a height (11.4%), and sports related slips (10.6%) were other causes. All humeral shaft fractures caused by forceful contraction were spiral, while 40% of the fractures caused by external force related events were of a transverse type. The percentage of left-sided fractures was significantly higher for fractures arising from an external force than in those caused by forceful contraction related events. Radial nerve palsy was found in 34 patients (27.6%), and 16 were discharged from the military because of prolonged radial nerve palsy 6 months after the fracture. The causative events and other factors did not affect the presence of radial nerve palsy. CONCLUSION: Arm wrestling was the leading cause of humeral fracture in young Korean soldiers but the chance of developing comorbid radial nerve palsy did not differ from that of other causes. These epidemiologic findings in this young active group may help in understanding the causes of humeral shaft fracture in soldiers and in the wider young population.

Humeral stress shielding following cemented endoprosthetic reconstruction: An under-reported complication?

INTRODUCTION: The proximal humerus is a common location for primary and non-primary tumors. Reconstruction of the proximal humerus is commonly performed with an endoprosthesis with low rates of structural failure. The incidence and risk factors for stress shielding are under reported. METHODS: Thirty-nine (19 male, 20 female) patients underwent resection of the proximal humerus and reconstruction with a cemented modular endoprosthesis between 2000 and 2018. The mean resection length was 12 ± 4 cm and was most commonly performed for metastatic disease (n = 26, 67%). RESULTS: Stress shielding was observed in 9 (23%) patients at a mean of 29 (6-132) months postoperatively. Patients with stress shielding were noted to have shorter intramedullary stem length (87 vs. 107 mm, p < .001), longer extramedullary implant length (16 vs. 14 cm, p = .01) and a higher extramedullary implant to stem length ratio (2.1 vs. 1.1, p < .001). The incidence of stress shielding was higher (p = .003) in patients reconstructed with 75 mm stem (n = 6, 67%) lengths. CONCLUSION: Stress shielding of the humerus was associated with the use of shorter stems and long extramedullary implants. The long-term ramifications of stress shielding on implant stability, complications at the time of revision surgery, and overall patient outcomes remain unknown.

An Individualized Intra-Articular Stabilization Device Designed Based on 3D Printing Technology for Traumatic Instability of the Ulnohumeral Joint.

We aimed to design an individualized intra-articular stabilization device based on 3D printing technology and investigate the clinical effects of this device for treating traumatic instability of the ulnohumeral joint. This study enrolled nine patients with traumatic instability of the ulnohumeral joint (age: 47.2 ± 1.80 years) who received treatment between March 2018 and March 2019 in our hospital. All patients underwent a thin-layer computed tomography (CT) scan of the elbow before surgery. The original injury and repair models of the elbow were printed using 3D printing technology based on CT data. An individualized intra-articular stabilization device was designed with a 2.0 mm Kirschner wire based on the repair model. Nine patients agreed to receive surgical treatment for elbow disease and placement of the intra-articular stabilization device. The nine patients underwent open reduction through a posterior median approach, and the intra-articular stabilization device was placed in the elbow. Operation time, intraoperative blood loss, and postoperative complications were recorded and followed up. The device was removed at two postoperative months, and the Mayo score was used to evaluate elbow function. Four months after removing the intra-articular stabilization device, elbow joint function was evaluated again using the Mayo score. The mean operation time was 100.1 ± 8.2 min, and the mean intraoperative blood loss was 35.5 ± 7.1 ml. No complications occurred after operation. Two months after surgery, eight patients received an excellent Mayo score, and one patient received a good Mayo score. Four months after removal of the intra-articular stabilization device, eight patients received an excellent Mayo score, and one patient received a good Mayo score. The individualized intra-articular stabilization device can increase ulnohumeral stability and achieve rapid functional recovery of the elbow.

Ultrasonography-guided closed reduction in the treatment of displaced transphyseal fracture of the distal humerus.

BACKGROUND: To evaluate the clinical and radiographic outcomes of ultrasonography-guided closed reduction in the treatment of displaced transphyseal fracture of the distal humerus (TFDH). METHODS: Twenty-seven patients with displaced TFDH were successfully treated by the ultrasonography-guided closed reduction during January 2012 to December 2016 and were retrospectively reviewed. After the mean follow-up of 34.88 months, the clinical and radiographic outcomes of patients were evaluated. The cubitus varus of the affected elbows was also assessed at the latest follow-up. RESULTS: The successful rate of ultrasonography-guided closed reduction in the treatment of displaced TFDH was 84% (27/32). The twenty-seven patients with successful reduction were included for the following analysis. There were 20 males and 7 females included in the study, and the mean age at treatment was 15.39 ± 3.10 months; seventeen fractures occurred in the right side elbow and ten in the left side. At the last follow-up, there were significant decreases in the elbow flexion (3°, P = 0.027) and range of motion (5°, P = 0.003) between the injured and uninjured elbow, respectively, whereas no difference in elbow extension was detected (P = 0.110). Flynn's criteria assessment showed that all the patients achieved excellent or good outcomes both in the functional and cosmetic categories. The clinical and radiographic carrying angles at the last follow-up were 11.67 ± 3.11° and 10.46 ± 3.88°, respectively. And the incidence of cubitus varus after treatment was 7.4% at the last follow-up. CONCLUSION: The ultrasonography-guided closed reduction in the treatment of displaced TFDH is an effective procedure; the adequate fracture reduction can be acquired with the advantages of real-time, non-radioactive, and simple utilization. With the percutaneous pining fixation, satisfactory clinical and radiographic outcomes can be achieved with a low incidence of postoperative cubitus varus.

Arthroscopic fixation of humeral greater tuberosity fracture using a W-shaped suture.

BACKGROUND: Patients with greater tuberosity fractures of the humerus often require surgery. Therefore, there is a need to find a minimally invasive and effective surgical procedure with great patient outcomes. AIM: To evaluate the clinical outcomes of the W-shaped suture technique under shoulder arthroscopy in the treatment of greater tuberosity fractures of the humerus. METHODS: In this retrospective study, a total of 17 patients were included. The fractures were closed, and there was no neurovascular injury. These patients underwent arthroscopically assisted reduction and internal fixation of the greater tuberosity fractures. Fixation was performed using sighting nails combined with a W-shaped suture. The imaging data of the patients were collected, and the ASES score, Constant-Murley score, and VAS score were used to evaluate the patient's outcome. At the last follow-up (at least 1 year), the range of motion in the affected shoulder was compared with that of the contralateral side. RESULTS: The operation was successful in all the patients. The average follow-up time was 13 months. There were no reported complications such as fracture displacement, nonunion, and internal fixation failure during the follow-up period. Post-operative X-ray examinations revealed good function recovery, with a healing time of between 10 and 12 weeks, and an average healing time of 11.5 weeks. Following the operation, patients reported reduced shoulder joint pain that no longer influenced their activity or caused discomfort in their daily life. The patient's VAS score ranged from 0 to 3, with an average of 0.52 ± 0.73, while at the last follow-up, the Constant-Murley score ranged from 83 to 97, with an average of 92.33 ± 7.55. The ASES score ranged from 81 to 98, with an average of 93.15 ± 6.93. At the last follow-up, there was no significant difference in the overall range of motion with the unaffected limb. CONCLUSION: This study demonstrates that the W-shaped suture can be used to effectively fix the fractures of the greater tuberosity of the humerus, by increasing the fixed area to promote healing.

Upper extremity prosthetic selection influences loading of transhumeral osseointegrated systems.

Percutaneous osseointegrated (OI) implants are increasingly viable as an alternative to socket suspension of prosthetic limbs. Upper extremity prostheses have also become more complex to better replicate hand and arm function and attempt to recreate pre-amputation functional levels. With more functionality comes heavier devices that put more stress on the bone-implant interface, which could be an issue for implant stability. This study quantified transhumeral loading at defined amputation levels using four simulated prosthetic limb-types: (1) body powered hook, (2) myoelectric hook, (3) myoelectric hand, and (4) advanced prosthetic limb. Computational models were constructed to replicate the weight distribution of each prosthesis type, then applied to motion capture data collected during Advanced Activities of Daily Living (AADLs). For activities that did not include a handheld weight, the body powered prosthesis bending moments were 13-33% (range of means for each activity across amputation levels) of the intact arm moments (reference 100%), torsional moments were 12-15%, and axial pullout forces were 30-40% of the intact case (p≤0.001). The myoelectric hook and hand bending moments were 60-99%, torsional moments were 44-97%, and axial pullout forces were 62-101% of the intact case. The advanced prosthesis bending moments were 177-201%, torsional moments were 164-326%, and axial pullout forces were 133-185% of the intact case (p≤0.001). The addition of a handheld weight for briefcase carry and jug lift activities reduced the overall impact of the prosthetic model itself, where the body powered forces and moments were much closer to those of the intact model, and more complex prostheses further increased forces and moments beyond the intact arm levels. These results reveal a ranked order in loading magnitude according to complexity of the prosthetic device, and highlight the importance of considering the patient's desired terminal device when planning post-operative percutaneous OI rehabilitation and training.

A systematic review of tuberosity healing and outcomes following reverse shoulder arthroplasty for fracture according to humeral inclination of the prosthesis.

BACKGROUND: Proximal humerus fractures are common in the elderly population and are often treated with reverse shoulder arthroplasty (RSA). The purpose of this systematic review was to compare tuberosity healing and functional outcomes in patients undergoing RSA with humeral inclinations of 135°, 145°, and 155°. METHODS: A systematic review was performed of RSA for proximal humerus fracture using Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) guidelines. Radiographic and functional outcome data were extracted to evaluate tuberosity healing according to humeral inclination. Analysis was also performed of healed vs. nonhealed tuberosities. RESULTS: A total of 873 patients in 21 studies were included in the analysis. The mean age was 77.5 years (range of 58-97) and the mean follow-up was 26.2 months. Tuberosity healing was 83% in the 135° group compared with 69% in the 145° group and 66% in the 155° group (P = .030). Postoperative abduction was highest in the 155° group (P < .001). No significant difference was found in forward flexion, external rotation, or postoperative Constant score between groups. Patients with tuberosity healing demonstrated 18° higher forward flexion (P = .008) and 16° greater external rotation (P < .001) than those with unhealed tuberosities. CONCLUSION: RSA for fracture with 135° humeral inclination is associated with higher tuberosity healing rates compared with 145° or 155°. Postoperative abduction is highest with a 155° implant, but there is no difference in in postoperative forward flexion, external rotation, or Constant score according to humeral inclination. Patients with healed tuberosities have superior postoperative forward flexion and external rotation than those with unhealed tuberosities.

Cartilage Homeostasis Affects Femoral Head Necrosis Induced by Methylprednisolone in Broilers.

(1) Background: Since the large-scale poultry industry has been established, femoral head necrosis (FHN) has always been a major leg disease in fast-growing broilers worldwide. Previous research suggested that cartilage homeostasis could be taken into consideration in the cause of FHN, but the evidence is insufficient. (2) Methods: One-day-old broiler chickens were randomly divided into three groups, 16 broilers per group. The birds in group L were injected intramuscularly with methylprednisolone (MP) twice a week for four weeks (12.5 mg·kg-1). The birds in group H were injected intramuscularly with MP (20 mg·kg-1·d-1) for 7 d (impulse treatment). The birds in group C were treated with sterile saline as a control group. Broilers were sacrificed at 42 and 56 d. Blood samples were collected from the jugular vein for ELISA and biochemical analysis. Bone samples, including femur, tibia, and humerus, were collected for histopathological analysis, bone parameters detection, and real-time quantitative PCR detection. (3) Results: The FHN broilers in group L and H both showed lower body weight (BW) and reduced bone parameters. In addition, the MP treatment resulted in reduced extracellular matrix (ECM) anabolism and enhanced ECM catabolism. Meanwhile, the autophagy and apoptosis of chondrocytes were enhanced, which led to the destruction of cartilage homeostasis. Moreover, the impulse MP injection increased the portion of birds with severer FHN, whereas the MP injection over a long period caused a more evident change in serum cytokine concentrations and bone metabolism indicators. (4) Conclusions: The imbalance of cartilage homeostasis may play a critical role in the development of FHN in broilers. FHN broilers induced by MP showed a more pronounced production of catabolic factors and suppressed the anabolic factors, which might activate the genes of the WNT signal pathway and hypoxia-inducible factors (HIFs), and then upregulate the transcription expression of ECM to restore homeostasis.

Evaluation of stabilization of intra-articular fracture of distal humerus - finite element study.

PURPOSE: The treatment of comminuted fractures of distal humerus poses a challenge for orthopaedics. Previous studies assessing the global stiffness of the bone - stabilizer system - made it impossible to explicitly indicate an optimal configuration of the locking plates in the treatment of this kind of fractures. The aim of the present research was to comparatively analyze the stabilization conditions of intraarticular fractures of distal humerus with the use of various configurations of the stabilizer. METHODS: The research was based on the analysis of mutual displacements of bone fragments. Such evaluation was performed with the use of numerical simulation conducted with the use of the finite element method. A realistic model of humerus was based on the CT data. Three spatial configurations of the stabilizer (parallel, posteromedial and posterolateral) were considered. The mutual displacements of bone fragments as well as the deformity of the stabilizer under various loading conditions were analyzed. RESULTS: In most cases, the parallel setting of the plates ensures a better stabilization of the bone fragments than the perpendicular configuration. The most difficult conditions of stabilization were obtained for the lateral bone fragment. The value of the fragments' displacements significantly increases for loading directions occurring with ascending flexion angle of the joint. CONCLUSIONS: In most cases, the parallel setting of the plates ensures a better stabilization of the bone fragments than the perpendicular configuration.

Three-dimensional Volumetric Filling Ratio Predicts Stress Shielding in Short-stem Anatomic Total Shoulder Arthroplasty.

INTRODUCTION: Three-dimensional (3-D) CT volumetric filling ratio (VFR) is a better predictor of proximal humerus stress shielding after short-stem anatomic total shoulder arthroplasty (aTSA) than using plain radiographs. METHODS: Forty-four patients with short-stem aTSAs, preoperative CT scans, and a minimum 3-year radiographic follow-up were included. Patients were divided into group A (stress shielding) and group B (no stress shielding) based on the radiographic analysis. Standard implant filling ratios were measured on plain radiographs. The 3-D VFR of the metaphyseal and diaphyseal segments of the aTSA stem was measured using MIMICS (Materialise). The area under a receiver operator characteristic curve was used to determine the predictive strength of the 3-D VFR method. RESULTS: The average age and radiographic follow-up was 69 years and 44 months. Group A had 19 patients and statistically higher filling ratios using 3-D VFR method than group B, whereas no notable differences were found between the groups using standard techniques. The 3-D VFR had an area under a receiver operator characteristic curve of 92%, which supports it as a good predictor of stress shielding. CONCLUSIONS: These methods enable early identification of patients at risk for stress shielding and can also be valuable in improving humeral stem designs. LEVEL OF EVIDENCE: Level III. Case-control study.

Does humeral torsion play a role in shoulder and elbow injury profiles of overhead athletes: a systematic review.

BACKGROUND: Humeral retrotorsion (HRT) is one bony adaptation that occurs in overhead athletes. This bony adaptation often leads to bilateral changes in range of motion at the glenohumeral joint. Because HRT can create different stress environments on the surrounding tissue, it may play a role in upper-limb injury and pain profiles. Therefore, the aim of this review was to examine whether HRT plays a role in shoulder and elbow injury profiles. METHODS: Two separate critical appraisal tools were administered: the Newcastle-Ottawa Scale (case control) and the Appraisal Tool for Cross-sectional Studies. The primary author extracted all data and obtained means and standard deviations for each outcome. Cohen d effect sizes (ESs) were calculated (ES [95% confidence interval]) for all HRT measurements including nondominant, dominant, and side-to-side differences. Finally, the Strength of Recommendation Taxonomy was used to evaluate the overall strength of the recommendation. RESULTS: Nine articles were included in this review. Large ESs were present in 2 studies on examination of symptomatic and asymptomatic dominant HRT and ranged between 0.83 (0.08-1.55) and -2.57 (-3.66 to 1.99). The majority of all ESs for all HRT measurements were moderate or low, rendering comparisons between asymptomatic and symptomatic cohorts that were not clinically meaningful. CONCLUSION: The Strength of Recommendation Taxonomy rating was C based on inconsistent findings. Differences in sports populations and definitions of injuries across studies may be one reason for the varying ESs. HRT does occur in the overhead population, but the degree to which this HRT starts to affect upper-limb injury is unknown and is more than likely player specific and multifactorial.

Tuberosity healing improves functional outcome following primary reverse shoulder arthroplasty for proximal humeral fractures with a 135° prosthesis.

INTRODUCTION: Reverse shoulder arthroplasty (RSA) is a common treatment for proximal humeral fractures (PHFs) in the elderly. This study evaluates the influence of tuberosity healing (TH) on functional outcome following a 135° humeral inclination RSA for PHFs. METHODS: Retrospectively, all patients with an acute PHF treated with a 135° humeral inclination RSA at four centers during a three-year period were followed up. Constant score (CS), TH and glenoid notching were analyzed. RESULTS: Sixty-four of 100 patients (64%) with a mean age of 76 ± 7 years were available for follow-up at 22 ± 8 months. The mean-adjusted CS was 72%. TH of the greater tuberosity (GT) was 77% and resulted in significantly improved forward flexion (128° vs. 92°; p = 0.003), external rotation (33° vs. 17°; p = 0.03) and adjusted CS (78% vs. 54%, p < 0.005). GT healing rate was 86% with neutral, 70% with lateralized and 33% with an inferior eccentric glenosphere. TH of the lesser tuberosity was 79%. There was 8% complication and 3% revision rate; implant survival was 100%. CONCLUSION: RSA with 135° humeral inclination for PHFs leads to good functional outcome, reproducible results and a high rate of TH. The short-term revision rate is low. TH is associated with improved ROM and functional outcome. LEVEL OF EVIDENCE: III.