How to avoid baseplate failure: the effect of compression and reverse shoulder arthroplasty baseplate design on implant stability.

BACKGROUND: Failure to achieve fixation of the glenoid baseplate will lead to clinical failure. The fixation of the baseplate to the scapula must be able to withstand sufficient shear forces to allow bony ingrowth. The importance of compression to neutralize the forces at the baseplate-bone interface has been assumed to be critical in limiting excessive micromotion. The purpose of this study is to determine the effect of compression on implant stability with different baseplate designs. METHODS: Various baseplate designs (1-piece monolithic central screw [1P], 2-piece locking central screw [2PL], and 2-piece nonlocking center screw [2PNL]) were investigated at 3 different compressive forces (high [810 N], medium [640 N], and low [530 N]). Synthetic bone cylinders were instrumented, and peripheral screws were used in all models. The combination of 1 locking and 3 nonlocking peripheral screw fixation was selected as worst-case scenario. Dynamic testing protocol followed the ASTM F2028-17 standard. The baseplate micromotion at high compression was compared to low compression. Additionally, the baseplate micromotion for each design was compared at baseline (first 50 cycles) and at 10,000 cycles for the 3 different compressive forces where motion above 150 µm was defined as failure. RESULTS: Baseplate micromotion was found to negatively correlate with compression (rpb = -0.83, P < .0001). At baseline, all baseplate designs were considered stable, regardless of compression. With high compression, average micromotion at the glenoid baseplate-bone interface remained below the 150-µm threshold for all baseplate designs at 10,000 cycles (1P: 50 ± 10 µm; 2PL: 78 ± 32 µm; 2PNL: 79 ± 8 µm; P = .060). With medium compression, average micromotion at 10,000 cycles for all 3 designs remained below the 150-µm threshold (1P: 88 ± 22 µm; 2PL: 132 ± 26 µm; 2PNL: 107 ± 39 µm). The 2PL design had the highest amount of micromotion (P = .013). With low compression, both 2-piece designs had an average micromotion above the 150-µm threshold whereas the 1-piece design did not (1P: 133 ± 35 µm; 2PL: 183 ± 21 µm; 2PNL: 166 ± 39 µm). The 2PL design had significantly higher micromotion when compared to 1P design (P = .041). DISCUSSION: The stability of a central screw baseplate correlates with the amount of compression obtained and is affected by implant design. For the same amount of compression, more micromotion is observed in a 2-piece design than a 1-piece design.

Effectiveness and safety of caplacizumab in acquired thrombotic thrombocytopenic purpura: health technology assessment and classification according to the methodology established in Colombia.

OBJECTIVES: Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare hematological disease whose clinical management includes caplacizumab along with plasma exchange and immunosuppression, according to international guidelines. Caplacizumab has been available in Colombia since 2022. This study seeks to determine the therapeutic classification of caplacizumab according to the methodology of the Instituto de Evaluación Tecnológica en Salud. METHODS: The classification was carried out through a deliberative process following the modified Delphi technique, with a panel of experts, made up of four hemato-oncologists, a pharmaceutical chemist, and a patient. The results of effectiveness and safety obtained through a systematic review, therapeutic thresholds (clinical significance), and degree of acceptability (willingness to use the technology) were used for the classification. RESULTS: Fourteen effectiveness and safety outcomes were submitted for the classification process. Caplacizumab showed clinical significance for some effectiveness outcomes, was not considered inferior in terms of safety, and displayed acceptability of use. Through consensus, the panel determined that caplacizumab plus the standard regimen is superior to the standard regimen in terms of treatment response and composite outcome, and no different for the other effectiveness and safety outcomes. Likewise, in overall terms, the panel determined that caplacizumab together with the standard regimen is superior to the standard regimen. CONCLUSION: Treatment with caplacizumab together with the standard regimen was considered superior to the standard regimen for the treatment of patients with aTTP, as it showed clinically significant benefits in critical outcomes for decision making, and a safety profile no different to its comparator.

Glenoid-based reference system to differentiate shoulder pathologies on plain radiographs.

BACKGROUND: Shoulder radiographs are used for evaluation and the planning of treatment of various pathologies. Making a diagnosis of these pathologies on plain radiographs occurs by recognizing the relationship of the humeral head on the registry of the glenoid. Quantification of these changes in registry does not currently exist. We hypothesize that a geometric relationship of the humeral head and the glenoid exists that is defined on an anteroposterior Grashey view radiograph by the relationship of the best-fit circle of the humeral head relative to the best-fit circle of the glenoid such that relative measurements will define the normal shoulder and the pathologic shoulder. METHODS: One hundred fifty-six shoulders were included: 53 normal shoulders, 51 with primary glenohumeral osteoarthritis (GHOA), and 52 with cuff tear arthropathy (CTA). Humeral head best-fit circle was used to define the circle of the humeral head (cHH). A glenoid best-fit circle (cG) was defined by the following rules: (1) best fit of the glenoid articular surface and (2) was limited by the acromion such that either (a) it reaches maximal interaction with the inferior surface of the acromion or (b) the perimeter of the circle is at the lateralmost point of the acromion. The relationship between cHH and cG is defined by measurement of cHH in horizontal and vertical planes relative to the glenoid circle reference. The horizontal displacement angle (HDA) measures the horizontal position of cHH relative to cG, representing the degree of medialization toward the glenoid. The vertical displacement angle (VDA) measures the vertical position of cHH relative to cG, representing the degree of superiorization toward the acromion. Angles were compared by diagnosis and sex. RESULTS: The mean HDA was 61.0° (95% confidence interval [CI] 60.3°-61.7°) in normal shoulders, 79.9° (95% CI 76.9°-82.9°) in GHOA, and 63.4° (95% CI 61.7°-65.1°) in CTA (P < .001). The mean VDA was 43.1° (95% CI 42.2°-44.0°) in normal shoulders, 40.9° (95% CI 39.9°-42.0°) in GHOA, and 59.7° (95% CI 57.6°-61.7°) in CTA (P < .001). Interobserver reliability was 0.991 (95% CI 0.94-1.0) and intraobserver reliability was 0.998 (95% CI 0.99-1.0). The geometric relationship of cHH to the glenoid circle reference was plotted for each group. CONCLUSION: A geometric relationship exists of the humeral head in reference to the glenoid circle. Together, the HDA and the VDA distinguish between a normal shoulder and those with GHOA or CTA. This suggests that this novel methodology may provide a preoperative planning tool that is easily accessible.

Peptides DLL37-1 and LL37-1, an alternative to inhibit biofilm formation in clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis.

Staphylococcus aureus and Staphylococcus epidermidis have microbial surface components recognizing adhesive matrix molecules (MSCRAMM) adhesion proteins that enhance their biofilm formation ability, as well as virulence factors that influence morbidity and mortality in hospital settings. In this work, four peptides analogous of the peptide LL-37 that were evaluated to inhibit biofilm formation and its action potential on the expression of MSCRAMM proteins in clinical isolates through different tests, such as crystal violet, PCR and qPCR. In total, 96.8% of S. aureus were strong in biofilm formation in contrast to 48.4% of S. epidermidis. sdrG and sdrF genes were present in 100% of S. epidermidis strains and in all isolates. In S. aureus, specific genes that code for MSCRAMM proteins were detected: clfA (89%), clFB, sdrC and fnBA (94%). The peptides did not show hemolytic or cytotoxic activity. In this study, it was evidenced that of the peptides DLL37-1 at a 5 µM concentration was an efficacious antimicrobial agent and depicted greater biofilm inhibition in both bacterial species. Exhibiting a significant inhibition rate in S. aureus, this peptide caused a negative regulation in the expression of the genes clfA and sdrC, showed greater biological activity.

Identifying areas of screw fixation in glenoids with severe bone loss in shoulder arthroplasty.

BACKGROUND: Severe glenoid bone loss (SGBL) poses significant technical challenges. Adequate fixation of glenoid implants may require the use of alternative screw placement. Although bone volumes for the spine and lateral pillars have previously been defined, insufficient evidence exists regarding the distribution of screw placement for fixation in such regions for cases with SGBL. The purpose of this study is to evaluate the variability of screw placement. We hypothesize that determining this variability and establishing common patterns of glenoid bone loss will allow for recommendations for preoperative planning, and implant design and selection. METHODS: An internal registry of 2 high-volume shoulder and elbow surgeons was queried, and 65 three-dimensional scapulae models exhibiting SGBL were identified. A fellowship-trained shoulder and elbow surgeon simulated the placement of two 3.5 mm × 30 mm screws, one in the scapular spine (CS) bone volume and one in the inferior column (IS) bone volume. Three orthogonal reference planes were created using anatomic reference points: the scapula trigonum, estimated glenoid center, and inferior pole. Screw positions were mapped, and deviations from the reference planes were calculated. Mutual positions of the IS to CS were also computed. Intraobserver reliability was assessed using 10 randomly selected samples. Median and 25th and 75th percentiles were reported for screw orientation distributions. Means and standard deviations were reported for screw head positions. RESULTS: We demonstrated excellent intraobserver reliability (intraclass correlation coefficients, 0.90-0.98). Fifty percent of CS were oriented 10° ± 5° of retroversion from the scapula plane, with 5° ± 5° of inclination. For IS, 50% were positioned 0° ± 4° from the scapula plane, with -33° ± 7° of inclination. The relationship of the IS with the CS was medial and posterior in 49% of cases, lateral and posterior in 45%, and lateral and anterior in 6% of cases. On average, the distance between the CS and IS heads was 25 mm ± 4 mm. DISCUSSION: For SGBL, adequate fixation of glenoid implants can be achieved by placing screws in the spine and lateral columns, with excellent reproducibility. Future implant designs should accommodate CS positioned -16° to -5° from the scapula plane, with 0° to 12° of inclination, and IS positioned -6° to 4° from the scapula plane, with -40° to -25° of inclination. Moreover, mutual screw positions suggested bone loss distributions anteriorly and inferiorly. Future implant designs should consider the potential benefits of augmentation to accommodate interscrew distances of 21-29 mm and anatomic locations of the IS relative to the CS.

Locating Ships Using Time Reversal and Matrix Pencil Method by Their Underwater Acoustic Signals.

This paper presents a technique, based on the matrix pencil method (MPM), for the compression of underwater acoustic signals produced by boat engines. The compressed signal, represented by its complex resonance expansion, is intended to be sent over a low-bit-rate wireless communication channel. We demonstrate that the method can provide data compression greater than 60%, ensuring a correlation greater than 93% between the reconstructed and the original signal, at a sampling frequency of 2.2 kHz. Once the signal was reconstituted, a localization process was carried out with the time reversal method (TR) using information from four different sensors in a simulation environment. This process sought to achieve the identification of the position of the ship using only passive sensors, considering two different sensor arrangements.

The Human Digestive Tract Is Capable of Degrading Gluten from Birth.

The human gastrointestinal system has the capacity to metabolize dietary gluten. The capacity to degrade gliadin-derived peptide is present in humans from birth and increases during the first stages of life (up to 6-12 months of age). Fecal samples from 151 new-born and adult non-celiac disease (NCD) volunteers were collected, and glutenase and glianidase activities were evaluated. The capacity of total fecal proteins to metabolize 33-mer, 19-mer, and 13-mer gliadin peptides was also evaluated by high-performance liquid chromatography (HPLC). Feces from new-borns (meconium) showed glutenase and gliadinase activities, and peptidase activity against all three gliadin peptides. Maximal gluten degradative activity was observed in fecal samples from the youngest volunteers (0-12 months old). After the age of nine months, the gluten digestive capacity of gastrointestinal tract decreases and, from ±8 years old, individuals lose the ability to completely degrade toxic peptides. The gastrointestinal proteases involved in gluten digestion: elastase 2A, elastase 3B, and carboxipeptidase A1 are present from earlier stages of life. The human digestive tract contains the proteins capable of metabolizing gluten from birth, even before starting gluten intake. Humans are born with the ability to digest gluten and to completely degrade the potentially toxic gliadin-derived peptides (33-, 19-, and 13-mer).

Rupture or traumatic dislocation of cranial suture on infants, involvement of the lambdoidal accessory bones (Wormian bones): case presentation and analysis.

BACKGROUND: Sutural or Wormian bones are accessory bones of genetic and hereditary relevance, considered as ethnic and anatomical variables. Recently, they have been related to a certain type of congenital alterations such as osteogenesis imperfecta; however, there is no description in the literature of their involvement in skull fractures in infants. CASE PRESENTATION: We present a case of a male patient aged 15 months who suffered a fall from the stairs of his home approximately 6 h before arrival in the emergency room. This fall of approximately 1 m in height and with an area of direct impact on the right occipito-parietal region with no apparent loss of consciousness. At admission, with a Glasgow of 14 for irritability with subgaleal hematoma and cranial endostosis on occipitoparietal region, no more neurological signs were present. A CT scan of the skull was performed showing an occipital-parietal discontinuity at the lambdoid suture, and the scan also showed that a displacement occurred below the thickness of the adjacent bone. In addition, radiographic evidence showed a high possibility of dural penetration and an area of adjacent hemorrhagic contusion. Due to these findings, a surgical approach was decided upon. The findings in the surgical procedure were a complete dislocation (rupture) of lambdoidal cranial suture on the occipital border of the accessory bone (Wormian bone) with dura mater tear on the rupture tracing. A craniotomy was performed with dural plasty without eventualities. Forty-eight hours after surgery, he was discharged home in a stable neurologic condition. CONCLUSIONS: The present report shows the implications of approaching this type of injury, which can be confused as a depressed skull fracture. There is no description in the literature of a sutural rupture associated with Wormian bones.

Effect of the pesticide lindane on the biomass of the microalgae Nannochloris oculata.

This study assesses the growth of the microalgae Nannochloris oculata in the presence of lindane and the ability of N. oculata to remove lindane from media. Algal biomass increased with 0.1 and 0.5 mg L-1 of lindane, and lindane concentrations in the media decreased. N. oculata removed 73% and 68.2% of lindane in the 0.1 and 0.5 mg L-1 media concentrations, respectively. Algal biomass decreased to the level of the control at lindane concentrations greater than 2.5 mg L-1, probably due to toxicity. N. oculata removed lindane from the media at concentrations lower than 1.0 mg L-1. Thus, N. oculata may be useful for lindane bioremediation in contaminated aquatic systems.

Reactive oxygen species production induced by ethanol in Saccharomyces cerevisiae increases because of a dysfunctional mitochondrial iron-sulfur cluster assembly system.

Ethanol accumulation during fermentation contributes to the toxic effects in Saccharomyces cerevisiae, impairing its viability and fermentative capabilities. The iron-sulfur (Fe-S) cluster biogenesis is encoded by the ISC genes. Reactive oxygen species (ROS) generation is associated with iron release from Fe-S-containing enzymes. We evaluated ethanol toxicity, ROS generation, antioxidant response and mitochondrial integrity in S. cerevisiae ISC mutants. These mutants showed an impaired tolerance to ethanol. ROS generation increased substantially when ethanol accumulated at toxic concentrations under the fermentation process. At the cellular and mitochondrial levels, ROS were increased in yeast treated with ethanol and increased to a higher level in the ssq1∆, isa1∆, iba57∆ and grx5∆ mutants - hydrogen peroxide and superoxide were the main molecules detected. Additionally, ethanol treatment decreased GSH/GSSG ratio and increased catalase activity in the ISC mutants. Examination of cytochrome c integrity indicated that mitochondrial apoptosis was triggered following ethanol treatment. The findings indicate that the mechanism of ethanol toxicity occurs via ROS generation dependent on ISC assembly system functionality. In addition, mutations in the ISC genes in S. cerevisiae contribute to the increase in ROS concentration at the mitochondrial and cellular level, leading to depletion of the antioxidant responses and finally to mitochondrial apoptosis.

Improving glenoid-side load sharing in a virtual reverse shoulder arthroplasty model.

BACKGROUND: The goal of glenoid fixation in reverse shoulder arthroplasty (RSA) is to provide a stable environment to allow bony ingrowth into the baseplate. When this does not occur, eventual baseplate failure is likely. This study aims to determine the additional implant-bone contact achieved when the glenosphere undersurface is in contact with the glenoid and if this increase in implant-bone contact improves stability through load sharing with respect to baseplate fixation. We hypothesize that substantial increases in contact area are possible and that this increased contact area will improve baseplate stability through load sharing. METHODS: A computer-assisted design program was used to create 3-dimensional models of 7 currently available RSA devices. Total implant-bone contact area was compared in 2 conditions: (1) baseplate flush with bone and no additional glenosphere contact, or (2) baseplate and glenosphere undersurface in contact with bone. Next, finite element models were created from a commercially available system. Micromotion and stress were computed for each size of implant in the 2 conditions. RESULTS: All devices tested can achieve increased total contact area when the glenosphere is in contact with bone. Stress and micromotion were reduced when comparing condition 2 with condition 1 in all sizes of one commercially available system. The average micromotion decreased 37%, from 98.04 to 61.97 µm. Larger glenospheres experienced a greater reduction in micromotion. Likewise, average von Mises stress decreased 26%, from 3.29 to 2.42 MPa. CONCLUSION: Increasing glenosphere size and allowing glenosphere undersurface contact increased overall implant-bone contact area and baseplate stability.

Reverse shoulder arthroplasty components and surgical techniques that restore glenohumeral motion.

BACKGROUND: Modifications in reverse shoulder arthroplasty (RSA) have been made with the intent of maximizing motion, although there is little objective evidence outlining their benefit. This study investigated the RSA component combinations that impart the greatest effect on impingement-free glenohumeral motion. METHODS: A previously validated virtual shoulder model was implanted with RSA components that varied by humeral implant type (inset/onset), glenosphere diameter (30, 36, and 42 mm), glenosphere placement (inferior/neutral), glenosphere center-of-rotation offset (0, 5, and 10 mm), humeral neck-shaft angle (130° and 150°), and humeral offset (zero, five, and ten mm). Motion was simulated in all technique combinations until the point of impingement in abduction, flexion/extension (F/E), and internal/external rotation (IR/ER). Regression analysis was used to rank combinations based on motion. RESULTS: Of 216 possible study combinations, 126 constructs (58%) demonstrated no arm-at-side impingement and were included for analysis. Models with the largest motion in abduction, F/E, and IR/ER, respectively, were inset-42-inferior-10-150-zero (107°), inset-36-inferior-10-130-five (146°), and inset-42-inferior-10-130-ten (121°). Humeral neck-shaft angle, glenosphere center-of-rotation offset, glenosphere placement, and glenosphere diameter had a significant effect on motion in all planes tested. Of these variables, humeral neck-shaft angle was most predictive of a change in abduction and F/E motion, whereas glenosphere placement was most predictive of a change in IR/ER motion. CONCLUSION: Higher glenosphere center-of-rotation offsets led to an increase in motion in all planes. To maximize motion in abduction, a valgus humeral component should be selected; to maximize F/E, a varus humeral component should be selected; and, to maximize IR/ER, the glenosphere should be placed inferiorly.

[Temporomandibular manifestation in patients with Ehlers-Danlos syndrome: a systematic review]. / Manifestaciones temporomandibulares en pacientes con síndrome de Ehlers-Danlos: una revisión sistemática.

Introduction: Ehlers-Danlos Syndrome (EDS) consists of a group of diseases that imply a disorder among individuals connective tissue due to an altered collagen production. Fibrocartilaginous structures, support ligaments, disc and retrodiscal from the temporomandibular joint are composed primarily of collagen. Objective: Identify TMJ manifestations in patients with different types of EDS. Materials and Methods: a systematic review of the literature was performed on PubMed, Scopus and Web of Science databases. Observational studies and case series reports published either in spanish or panish were included up until January 2023. Results: 12 articles met the inclusion criterial. The prevalence of temporomandibular disorders varies from 26.6% to 100%, being EDSh the most reported subtype, whereas disc displacement with or without reduction and joint hypermobility were the most reported joint disorders. Conclusion: Temporomandibular pathologies are common in patients with EDS, especially in those with the EDSh subtype.

Solitary plasmacytoma of the sacrum treated with microwave ablation in conjunction with high dose of dexamethasone: A case report and review of the literature.

Background: Plasma cell neoplasms are characterized by the neoplastic proliferation of a single clone of plasma cells. Solitary plasmacytomas most often occur in bone, but they can also be found in soft tissues. Case Description: A 53-year-old male presented with localized sacral pain and urinary incontinence. His radiographic studies showed a solitary sacral plasmacytoma (i.e., involving the bone). He was successfully managed with high-dose dexamethasone and microwave ablation (MWA). Conclusion: Plasmacytomas of bone can be occasionally successfully managed with MWA, adjuvant cytoreduction therapy, and high doses of dexamethasone.

Hepatitis C virus infection and type 2 diabetes mellitus in Mexican patients.

OBJECTIVE: to measure the frequency of type 2 diabetes mellitus (T2DM) in patients with confirmed HCV infection. METHODS: we studied 125 adults reactive to anti-HCV antibodies (62.4 % women, mean age 46.8 years) who received confirmatory RT-PCR testing for viremia (63.2 % HCV-RNA-positive). RESULTS: twenty-two patients had T2DM (17.6 %, 95 % confidence interval: 11.8-25.3 %; mean National prevalence: 14.4 %), more frequent among patients with detectable viremia than in negative cases (23.3 % vs. 9.6 %, respectively; p = 0.04), and among those with advanced liver disease, than in compensated patients (28.9 % vs. 11.3 %, respectively; p = 0.01). Fourteen (17.7 %) patients received interferon-based treatment and 6 (42.8 %) had sustained virology response. None of the 6 responders had T2DM, but 2 of the 8 (25 %) non-responders had diabetes. T2DM patients were older than those without diabetes (57.7 vs. 44.5 years, p < 0.001), and after multivariate analysis, only age was significantly associated with diagnosis of T2DM. CONCLUSIONS: T2DM was highly prevalent among patients with chronic HCV infection. Age was the most important determining factor.

Teaching an old 'doc' new tricks for algal biotechnology: Strategic filter use enables multi-scale fluorescent protein signal detection.

Fluorescent proteins (FPs) are powerful reporters with a broad range of applications in gene expression and subcellular localization. High-throughput screening is often required to identify individual transformed cell lines in organisms that favor non-homologous-end-joining integration of transgenes into genomes, like in the model green microalga Chlamydomonas reinhardtii. Strategic transgene design, including genetic fusion of transgenes to FPs, and strain domestication have aided engineering efforts in this host but have not removed the need for screening large numbers of transformants to identify those with robust transgene expression levels. FPs facilitate transformant screening by providing a visual signal indicating transgene expression. However, limited combinations of FPs have been described in alga and inherent background fluorescence from cell pigments can hinder FP detection efforts depending on available infrastructure. Here, an updated set of algal nuclear genome-domesticated plasmid parts for seven FPs and six epitope tags were generated and tested in C. reinhardtii. Strategic filter selection was found to enable detection of up to five independent FPs signals from cyan to far-red separately from inherent chlorophyll fluorescence in live algae at the agar plate-level and also in protein electrophoresis gels. This work presents technical advances for algal engineering that can assist reporter detection efforts in other photosynthetic host cells or organisms with inherent background fluorescence.

Juvenile angiolipoma in the subtemporal region, zygomatic, and pterygomaxillary fossa treated by microwave ablation - A case study and literature review.

Background: Angiolipomas are benign mesenchymal tumors that infrequently affect the head-and-neck region and can appear with infiltrating and non-infiltrating forms. Surgical excision is the treatment of choice; however, there are other alternatives to manage this condition whose consideration is quite useful to evaluate per each particular case. Case Description: An 11-year-old girl was diagnosed with non-infiltrating angiolipoma in the subtemporal region, the zygomatic, and pterygomaxillary fossa; she had a history of having undergone surgery on two previous occasions with a failed resection attempt due to the high vascularization of the injury and significant transoperative bleeding. The condition was managed with minimally invasive techniques through microwave ablation, requiring two sessions, achieving very satisfactory results both esthetically and in the final size of the lesion. Conclusion: The microwave ablation technique may turn out to be a very useful tool for the management of lesions with high vascularization such as angiolipoma. This technique offers a new possibility for initial management, both independent of and complementary to other management techniques for other lesions at the base of the skull and/or facial massif regions.

Torsional stability of modular and non-modular reverse shoulder humeral components in a proximal humeral bone loss model.

HYPOTHESIS/BACKGROUND: Patients who are treated with reverse shoulder arthroplasty in the setting of proximal humeral bone loss present a technical challenge for humeral component fixation. The purpose of this study was to determine the effect of proximal humeral bone loss on fixation of reverse shoulder humeral implants. MATERIALS AND METHODS: Three reverse humeral designs (two modular and one monobloc) were cemented into twenty-four Sawbones humeri prepared to simulate intact and proximal humeral bone loss. Torque was applied to the humerus for 1,000 cycles in increments of 2.5 N-m to 25 N-m. Rotational micromotion of the implant was measured. RESULTS: There was a significant decrease in rotational micromotion in the intact constructs when compared with the bone loss constructs (we found P < .01 when looking at torsion levels of 5 to 17.5 N-m). In the intact humerus, 10 of 12 implant constructs survived testing. The 2 that failed were modular implants. In the bone loss setting, 7 of 12 implant constructs survived testing. The 5 that failed were also modular implants. CONCLUSIONS: This is the first investigation on humeral component fixation in reverse shoulder arthroplasty. The proximal humerus adds stability to the fixation of a cemented humeral implant. Modular components in the presence of proximal humeral bone loss may be at increased risk of mechanical failure. Conversely, non-modular cemented humeral components can withstand greater loads before failure.