Basic Science Evidence Research Articles

Biomechanical comparison of stemless humeral components in total shoulder arthroplasty

BackgroundThe purpose of this study was to compare initial fixation strength between various stemless and stemmed humeral components and to correlate implant fixation strength with bone mineral density (BMD). MethodsFive humeral stem designs were investigated: Stemless-A (four hollow fins), Stemless-B (central body, three solid fins), Stemless-C (central screw, peripheral rim-fit), Short stem (50 mm), and Standard stem (130 mm). Fifty cadaveric human humerii were obtained and divided into five groups. BMD within the humeral head was determined for all samples. The mean BMD was similar between groups. The 25 samples with the lowest and highest BMDs were categorized as “Low” and “High,” respectively, with a BMD threshold of 0.35 g/cm2, creating BMD subgroups. After implantation, each sample underwent a standardized biomechanical testing protocol, with axial loading followed by torsional loading. Sensors attached to the specimen recorded micromotion throughout testing. Axial loading consisted of cyclic loading for 100 cycles at 3 peak forces (220, 520, and 820 N). Torsional loading consisted of 100 cycles of internal/external rotation at 0.1 Hz at 6 peak torques, or until failure (±2.5, 5, 7.5, 10, 12.5, and 15 Nm). Failure was defined as the torque at which any bone fracture, implant detachment from anchor/stem, or an excess of 50° internal/external rotation occurred. Groups and BMD subgroups were compared. ResultsAt maximal axial loading, Stemless-B demonstrated greater micromotion (540 μm) than Stemless-C (192 μm) (P = .003). Stemless-B and Stemless-A (387 μm) also had greater micromotion than Short stem (118 μm, P < .001, P = .03) and Standard stem (85 μm, P < .001, P = .01). When comparing low-BMD samples at maximal axial loading, these differences were accentuated, but comparison of high-BMD samples showed no significant differences between groups. Torsional testing demonstrated that Standard stem failed at greater torque (7.2 Nm) than Stemless-B (2.3 Nm, P < .001), Stemless-A (1.9 Nm, P < .001), and Stemless-C (3.9 Nm, P = .01). When comparing torsional testing results of low-BMD samples, both Standard stem and Short stem failed at greater torque than Stemless-B (P = .02, P = .003) and Stemless-A (P = .03, P = .004) but failed at a similar torque to Stemless-C. Torsional testing of high-BMD samples showed that Standard stem failed at a greater torque than all stemless designs. ConclusionStemless humeral implants should be used with caution in low-BMD settings (<0.35 g/cm2). A central screw and peripheral rim-fit stemless anchor design demonstrated greater fixation strength at low BMD when compared with other designs, while all stemless designs performed similarly at high BMD. Level of evidenceBasic Science Study; Cadaveric Study

Abstracts from Society for Acupuncture ResearchPandemics, Pain, &amp; Public Health:Roles and Relevance of Traditional East Asian MedicineJune 14–17, 2021

Abstracts from Society for Acupuncture ResearchPandemics, Pain, &amp; Public Health:Roles and Relevance of Traditional East Asian Medicine<i>June 14–17, 2021</i>

The role of the brachialis muscle in elbow stability with collateral ligament injury: A biomechanical investigation

BackgroundThe brachialis muscle lies in close anatomic relation to the anterior capsule of the elbow joint. The contribution of the brachialis muscle to elbow stability has not yet been fully investigated. Therefore, the aim of this biomechanical in-vitro study was to analyze its influence on joint stability. MethodsNine fresh frozen cadaveric elbows were evaluated for stability against valgus and varus/posterolateral rotatory forces. Brachialis loading was measured indirectly using strain gauges. Three distinct scenarios were analyzed: A) with intact lateral ulnar and ulnar collateral ligaments B) with a ruptured lateral ulnar collateral ligament C) with ruptured lateral ulnar and ulnar collateral ligaments. FindingsIn all scenarios, an increased strain was observed under posterolateral rotatory/varus forces. The maximum measured strain occurred with elbow flexion of 30° and pronation of the forearm. The strain was significantly higher with dual-ligament rupture (mean - 210.5 μm/m; min. 97.8 μm/m; max. -310 μm/m; SD 107.8 μm/m; p = .034) compared to intact ligaments (mean − 106.9 μm/m; min. -32.51 μm/m, max. -287 μm/m; SD 100.2 μm/m) and single-ligament rupture (mean – 109.5 μm/m; min. - 96.7 μm/m; max - 130.4 μm/m; SD 18.2). InterpretationA strain of the brachialis muscle was observed under varus/posterolateral rotatory forces with a pronated forearm and the strain increased significantly in the event of a dual-ligament rupture. This suggests that the brachialis muscle may influence varus/posterolateral rotatory stability of the elbow. Hence, a concomitant tear of the brachialis muscle might result in pronounced instability following simple elbow dislocation. Level of evidenceBasic Science Study, Biomechanics.

Effect of reverse total shoulder arthroplasty humeral inclination on glenohumeral range of motion, deltoid force, and glenoid strain: a biomechanical study

BackgroundReverse total shoulder arthroplasty (RSA) primarily varies between 2 implant design options: a 135 humeral stem inclination that closely resembles anatomic orientation, versus the Grammont-style 155 humeral stem inclination that further medializes and distalizes the center of rotation (COR). The purpose of this study was to compare deltoid force, glenoid strain, and simulated glenohumeral range of motion (ROM) between RSA 135 and RSA 155 designs, with a series of standardized permutations of glenosphere offset and rotator cuff pathology. MethodsTwelve fresh-frozen cadaveric shoulder specimens were studied using a shoulder simulator. Native shoulder motion profiles for reproducible abduction range of motion were established using a customized testing device. Optical 3-dimensional tracking and pressure sensors were used to accurately record glenohumeral range of motion (ROM), deltoid force, and glenoid strain for RSA 135 and RSA 155 designs. For each cohort, all combinations of glenosphere offsets and rotator cuff tendon involvement were evaluated. ResultsThere was no significant difference in the overall abduction ROM between the 155 and the 135 humeral stem implants (P = .75). Resting abduction angle and maximum abduction angle were significantly greater with a 155 + STD (standard offset) construct than with a 135 + STD construct (P < .001 and P = .01, respectively). Both stem inclinations decreased combined deltoid force requirements as compared the native shoulder with a massive cuff tear. Effective glenoid strain did not vary significantly between 135 + STD and 155 + STD constructs (P = .66). ConclusionOverall, range of motion between the 135 and the 155 humeral stem inclinations was not significantly different. The cumulative deltoid force was lower in RSA shoulders when compared to native shoulders with massive rotator cuff tears, highlighting the utility of both implant designs. The Grammont-style 155 stem coupled with a 2.5 mm inferior offset glenosphere required less deltoid force to reach maximum abduction than did the more anatomic, lateralized 135 stem coupled with a 4 mm lateral offset glenosphere. Level of EvidenceBasic Science, Biomechanics Controlled Laboratory Study

Common animal models lack a distinct glenoid labrum: a comparative anatomy study

PurposeDevelopment and validation of an animal model of labral healing would facilitate translation of novel surgical and biological strategies to improve glenolabral healing. The purpose of this study was to characterize the anatomic and histological properties of the shoulder labrum in rat, rabbit, dog, pig, goat, and humans. Given the demonstrated similarities in size and structural morphology in other joints, it was hypothesized that the goat glenoid with surrounding capsulolabral complex would most closely resemble that of humans in terms of dimensions and structure, as observed grossly and histologically.MethodsCadaveric glenohumeral joints from rats (n = 8), New Zealand white rabbits (n = 13), Mongrel dogs (n = 9), Spanish goats (n = 10), Yorkshire pigs (n = 10), and humans (n = 9) were freshly harvested. Photographs were taken of the glenoid with its surrounding capsulolabral complex. Linear dimensions of the glenoid articular surface were measured. It was determined where the capsulolabral complex was continuous with, or recessed from, the articular glenoid surface. The glenoid was divided into 6 equal segments radiating out toward 12, 2, 4, 6, 8, and 10 o’clock positions. Samples were sectioned and stained with Safranin O/Fast green and Mallory Trichrome. Insertion of the capsulolabral tissue onto the glenoid was qualitatively assessed and compared with gross morphology.ResultsDimensions of the goat glenoid most closely paralleled dimensions of the human glenoid. A capsulolabral complex was continuous with the glenoid surface from ~ 9 to 12 o’clock in the rats, 7 to 12 o’clock in rabbits, 5 to 12 o’clock in the dogs, and 9 to 12 o’clock in goats, 6 to 12 o’clock in pigs, and 2 to 8 o’clock in humans. In contrast to humans, no other species demonstrated an organized fibrocartilaginous labrum either macroscopically or histologically.ConclusionThe animals in the present study did not possess a discrete fibrocartilaginous labrum by gross or histological evaluation, as directly compared to humans. While models using these animals may be acceptable for examining other shoulder pathologies, they are not adequate to evaluate labral pathology.Level of evidenceBasic Science Study; Anatomy and Histology; Cadaveric Animal Model.

Intraoperative joint load evaluation of shoulder postures after reverse total shoulder arthroplasty: a cadaveric study using a humeral trial sensor

BackgroundThe effect of improper tension in reverse total shoulder arthroplasty (RTSA) can cause both joint looseness potentially leading to instability and dislocation and joint tightness potentially leading to limited joint motion and acromial or scapular spine stress fractures. Intra-articular load sensors offer an innovative technology providing information on real-time joint load parameters. The objective of this study is to evaluate a novel load sensor in a cadaveric RTSA model, to measure joint loads in shoulder positions required for activities of daily living (ADLs), with and without subscapularis repair. Our hypothesis is that an in situ joint load sensor can reliably measure the magnitude of joint load, and that subscapularis repair both increases joint load magnitude and improves the concentricity of the articulation at end range motion. MethodsNine freshly frozen full body cadaver shoulders were selected for this study. All shoulders were implanted with RTSA implants with the humeral insert incorporating a wireless load measuring sensor. Three ADL postures (“across chest”, “behind back”, and “overhead reach”) were each evaluated 5 times by a single observer that was blinded to the real time loads displayed by the sensor software interface. Joint load magnitude and resultant location of the load (centroid) were recorded for each ADL posture. The subscapularis was then repaired in the native location, and the ADL posture and load measurement protocol were repeated. ResultsAll 3 postures demonstrated an intra-class correlation coefficient of over 0.9, indicating high repeatability of the load magnitude measured on the same specimen. Load magnitudes ranged from 5 lbf to 70 lbf “where 1lbf = .454kgf” depending on the posture and position. Subscapularis repair statistically significantly increased mean joint loads in the behind back position (P = .046) and the “overhead reach” posture (P < .001). The centroid location differed between the “behind back” and “overhead reach” postures for both radial distance (R) and angular position (θ) (P < .05). Subscapularis repair did not change R or theta for any of the three ADL postures compared to testing with subscapularis unrepaired. DiscussionSensors placed within the trial insert can reliably measure joint loads in selected ADL postures. Subscapularis tendon repair increases the magnitude of joint load but does not appear to improve concentricity of resultant load when the shoulder is placed in ADL postures. Future work will involve sensor usage in a clinical setting to evaluate if measured joint load parameters correlate with improved clinical outcomes. Level of EvidenceBasic Science Study; Biomechanics

Abstract 846: Associations of dietary and lifestyle oxidative balance scores with all-cancer, all-CVD, and all-cause mortality risk among older women: The Iowa Women's Health Study

Abstract Background: Substantial basic science evidence suggests that oxidative stress may play a role in aging-related health outcomes, including cancer and cardiovascular diseases (CVD), and oxidative stress markers were linked with all-cancer, all-CVD, and all-cause mortality in epidemiologic studies. However, the associations of many individual dietary and lifestyle anti-/pro-oxidant exposures with mortality are inconsistent. Oxidative balance scores (OBS) that incorporated multiple dietary and lifestyle factors were previously developed and reported to reflect the collective oxidative effects of multiple exposures. Methods: We investigated associations of 11-component dietary and 4-component (physical activity, adiposity, alcohol, and smoking) lifestyle OBS (higher scores were considered more anti-oxidative) with all-cancer, all-CVD, and all-cause mortality among women 55 - 69 years of age at baseline in the prospective Iowa Women's Health Study (1986 - 2012). We assessed OBS-mortality associations using multivariable Cox proportional hazards regression. Results: Of the 34,137 cancer-free women included in the analytic cohort, 18,058 died (4,521 from cancer, and 6,825 from CVD) during a mean/median 22.0/26.1 person-years of follow up. Among participants in the highest relative to the lowest lifestyle OBS quintiles, the adjusted hazards ratios and their 95% confidence intervals for all-cancer, all-CVD, and all-cause mortality were 0.47 (0.43, 0.52), 0.54 (0.54, 0.58), and 0.50 (0.48, 0.53) (all Ptrend &amp;lt; 0.001), respectively. The associations of the dietary OBS with mortality were close to null. Conclusion: Our findings, combined with results from previous studies, suggest that a predominance of antioxidant over pro-oxidant lifestyle exposures may be associated with lower all-cancer, all-CVD, and all-cause mortality risk. Citation Format: Ziling Mao, Anna E. Prizment, DeAnn Lazovich, Boberd M. Bostick. Associations of dietary and lifestyle oxidative balance scores with all-cancer, all-CVD, and all-cause mortality risk among older women: The Iowa Women's Health Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 846.

Définition d’une différence minimale cliniquement significative pour les scores UCLA et ASES après réparation de la coiffe des rotateurs

Background/HypothesisMinimal clinically important difference (MCID) is a vital tool in the analysis of clinical results. It allows the determination of clinical relevance of statistical data. Our hypothesis was that specific differences between preoperative and postoperative scores would be able to accurately predict patient perception of improvement and satisfaction as reflected by anchor and distribution-based questions. MethodsRetrospective cohort with patients that underwent rotator cuff repair. We evaluated the University of California at Los Angeles Shoulder Rating Scale (UCLA) and the American Shoulder and Elbow Surgeons Assessment Form (ASES) before and 12-months after surgery. Anchor-based, distribution-based and minimum detectable change (MDC) approaches were utilized. ResultsWe evaluated 289 shoulders. The MCID for the UCLA scale was 4.5 points using the anchor method, 2.5 by the distribution method and 3.6 by MDC. Patients with a baseline score>20 presented a lower MCID (1.5, 1.1 and 1.7, respectively). For the ASES score, the MCID was 6.1 by the anchor method, 10.5 based on the distribution method and 26.3 by MDC. In the group of patients above the 60 point cutoff, the obtained values were 2.4, 4.9 and 13.6, respectively. ConclusionThe mean MCID value for the UCLA shoulder score is 3.5 points, ranging from 2.5 points (distribution method) to 4.5 points (anchor method). The mean MCID value for the ASES score was 15.2 points, ranging from 6.1 (anchor method) to 26.3 (MDC). Patients groups presenting with higher preoperative scores showed lower MCID values. This fact needs to be considered in postoperative comparisons between treatment groups. Level of evidenceBasic Science Study, Validation of Outcomes Instruments/Classification Systems.

The effect of proximal tibiofibular joint dislocation on knee mechanics: reduction and fixation matters.

Proximal tibiofibular joint (PTFJ) dislocations are under-investigated injuries. There is scant basic science or clinical evidence to direct management. The purpose of this study was twofold; first to investigate the pathomechanics of PTFJ dislocation on knee mechanics. The second purpose was to evaluate knee mechanics following reduction and fixation. Six cadaveric legs were tested on a mechanical platform. A 5Nm external rotation force was applied to each knee and the external rotation and fibular translation was measured for several study conditions at 0°, 30°, and 90° of flexion. Conditions included: the native state, transection of the posterior PTFJ ligament, transection of the anterior and posterior ligaments, screw fixation, and suspensory fixation. Screw fixation was performed using a single quadricortical 3.5mm screw. Suspensory fixation was performed using an Arthrex TightRope device RESULTS: Transection of the anterior and posterior ligaments increased external rotation by 4.3°, 5.9°, and 5.6°, at 0°, 30°, and 90° (p ≤ 0.001), respectively. Screw and suspensory fixation returned external rotation to a near native state with mild overconstraint. Complete transection of anterior and posterior ligaments resulted in pathologic anterior fibular translation of 1.51mm (p = 0.001), 1mm, (p = 0.02) and 0.44mm (p = 0.69) for 0°, 30°, 90° of knee flexion. Screw and suspensory fixation restored native translation at all points with a small degree of overconstraint. Disruption of the PTFJ causes pathologic external rotation and anterior fibular translation. Fixation restores near native motion with minor overconstraint. Surgeons should consider reduction and fixation of PTFJ injuries to restore native knee mechanics.

Infection prevention measures in acute care settings based on severe acute respiratory syndrome coronavirus 2 transmission patterns and risk: a review.

During the coronavirus disease 2019 pandemic, when facing extraordinary infection prevention challenges, acute care settings have balanced routine patient safety needs while minimizing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission risk to patients and healthcare personnel (HCP). Mitigation strategies in acute care settings are based on a combination of basic science, environmental, and epidemiologic evidence. Here, we review the literature on SARS-CoV-2 transmission, how it has shaped infection prevention interventions in acute care settings, and the results of such measures to reduce transmission. HCP adherence to transmission-based precautions in acute care settings, such as the use of personal protective equipment (PPE), is essential to mitigating SARS-CoV-2 spread. Although the SARS-CoV-2 virus has been isolated in nonrespiratory body sites, such exposure has not been shown to definitively cause transmission in humans. Epidemiologic evidence has demonstrated that implementation and adherence to infection prevention strategies reduces acute setting transmission. Given SARS-CoV-2 infection occurs primarily through respiratory transmission, preventing HCP acquisition requires fidelity to consistent PPE usage. Infection prevention strategies and implementation of transmission-based precautions have reduced spread and outbreaks. Epidemiologic studies of acute care outbreaks often include reports of PPE nonadherence and community exposure contributing to SARS-CoV-2 transmission within this setting.

Google Trends Analysis Shows Increasing Public Interest in Platelet-Rich Plasma Injections for Hip and Knee Osteoarthritis

BackgroundOsteoarthritis is a chronic musculoskeletal condition that frequently affects the hip and knee joints. Given the burden associated with surgical intervention for hip and knee osteoarthritis, patients continue to search for potential nonoperative treatments. One biologic therapy with mixed clinical and basic science evidence for treating osteoarthritis is platelet-rich plasma injections into the affected joint. We used the Google Trends tool to provide a quantitative analysis of national interest in platelet-rich plasma injections for hip and knee osteoarthritis. MethodsGoogle Trends parameters were selected to obtain search data from January 2009 to December 2019. Various combinations of “arthritis,” “osteoarthritis,” “PRP,” “platelet-rich plasma,” “knee,” and “hip” were entered into the Google Trends tool and trend analyses were performed. ResultsThree linear models were generated to display search volume trends in the United States for platelet-rich plasma and osteoarthritis, hip osteoarthritis, and knee osteoarthritis, respectively. All models showed increased Google queries as time progressed (P < .001), with R2 ranging from 0.837 to 0.940. Seasonal, income-related, and geographic variations in public interest in platelet-rich plasma for osteoarthritis were noted. ConclusionOur results demonstrate a significant rise in Google queries related to platelet-rich plasma injections for osteoarthritis of the hip and knee since 2009. Surgeons treating hip and knee osteoarthritis patients can expect continued interest in platelet-rich plasma, despite inconclusive clinical and basic science data. Trends in public interest may inform patient counseling, shared decision-making, and directions for future clinical research.

Analysis of the subcapital two-part humerus fracture by fluoroscopy: objective criteria for classification and decision making

BackgroundSurgical decision making in the treatment of proximal humerus fractures (PHFx) is primarily based on fracture classification using standard radiographs. Due to the lack of objective criteria, this classification process is associated with high interobserver variation. In this study, we investigate the fluoroscopic analysis of humerus fractures through the surgical neck using a semi-quantitative determination of distinct angulation patterns of the proximal humerus as they appear in the image intensifier.MethodsUsing a saw bone model, defined subcapital 2-part fracture configurations were generated and assessed radiographically. Anatomical landmarks—including the greater and lesser tuberosity as well as anatomical neck—were identified using an image converter, and the exact degree of fracture displacement with 10° up to 70° (in 10° increments) of posterior, varus or combined posterior-varus angulation was compared to nondisplaced controls. From the resultant series of radiographs, the appearance of these angulations in anteroposterior (AP) and scapular Y-views were also visualized and defined.ResultsAn angulation of 50° or more of any given 2-part fracture through the surgical neck is present when the greater tuberosity becomes the most proximal point in AP view (varus and combined posterior-varus angulation) or a bimodal form is found for the superior contour of the head with the lesser tuberosity being the most proximal point in the Y-view (posterior angulation).ConclusionThe radiological appearance of various PHFx constellations can be well visualized using the saw bone shoulder model. The presence of angulation in accordance with the Neer classification for group III fractures can be adequately determined by analyzing the relative position of the greater or lesser tuberosity to the humeral head calotte. This can assist the surgeon’s decision on whether to operate or opt for a conservative approach.Level of evidenceBasic Science, Anatomy Study, Imaging.

Progress for Immunotherapy in Inflammatory Breast Cancer and Emerging Barriers to Therapeutic Efficacy

Simple SummaryDespite recent advances in the treatment of other breast cancer subtypes, inflammatory breast cancer (IBC) remains a significant clinical challenge, with an overall 5-year survival rate of 39%. Though immunotherapy has shown remarkable efficacy in other difficult-to-treat cancers, such approaches have yet to show substantial therapeutic efficacy in IBC. Here, we summarize the known immune composition of IBC tumors, as well as past and present efforts to advance immunotherapy in the treatment of IBC.Inflammatory breast cancer (IBC) is a rare and aggressive subtype of breast cancer that carries a particularly poor prognosis. Despite the efficacy of immunotherapy in other difficult to treat forms of breast cancer, progress for immunotherapy in IBC has been difficult. Though immunotherapy has been under clinical investigation in IBC since the 1970s, few approaches have shown significant therapeutic efficacy, and no immunotherapy regimens are currently used in the treatment of IBC. Here, we provide a comprehensive summary of what is known about the immune composition of IBC tumors, clinical and basic science evidence describing the role for immune checkpoints such as PD-L1 in IBC pathobiology, as well as past and present attempts to advance ICIs in the treatment of IBC.

Bony Stress and Its Association With Intervertebral Disc Degeneration in the Lumbar Spine: A Systematic Review of Clinical and Basic Science Studies.

Study Design:Translational review encompassing basic science and clinical evidence.Objectives:Multiple components of the lumbar spine interact during its normal and pathological function. Bony stress in the lumbar spine is recognized as a factor in the development of pars interarticularis defect and stress fractures, but its relationship with intervertebral disc (IVD) degeneration is not well understood. Therefore, we conducted a systematic review to examine the relationship between bony stress and IVD degeneration.Methods:Online databases Scopus, PubMed and MEDLINE via OVID were searched for relevant studies published between January 1980-February 2020, using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Two authors independently analyzed the data, noting characteristics and biases in various studies.Results:Thirty-two articles were included in the review: 8 clinical studies, 9 finite element modeling studies, 3 in-vivo biomechanical testing studies, and 12 in-vitro biomechanical testing studies. Of the 32 articles, 19 supported, 4 rejected and 9 made no conclusion on the hypothesis that there is a positive associative relationship between IVD degeneration and bony stress. However, sufficient evidence was not available to confirm or reject a causal relationship.Conclusions:Most studies suggest that the prevalence of IVD degeneration increases in the presence of bony stress; whether a causal relationship exists is unclear. The literature recommends early diagnosis and clinical suspicion of IVD degeneration and bony stress. Longitudinal studies are required to explore causal relationships between IVD degeneration and bony stress.

Marked differences in local bone remodelling in response to different marrow stimulation techniques in a large animal.

Marrow stimulation, including subchondral drilling and microfracture, is the most commonly performed cartilage repair strategy, whereby the subchondral bone plate is perforated to release marrow-derived cells into a cartilage defect to initiate repair. Novel scaffolds and therapeutics are being designed to enhance and extend the positive short-term outcomes of this marrow stimulation. However, the translation of these newer treatments is hindered by bony abnormalities, including bone resorption, intralesional osteophytes, and bone cysts, that can arise after marrow stimulation. In this study, three different marrow stimulation approaches – microfracture, subchondral drilling and needle-puncture – were evaluated in a translationally relevant large-animal model, the Yucatan minipig. The objective of the study was to determine which method of marrow access (malleted awl, drilled Kirschner wire or spring-loaded needle) best preserved the underlying subchondral bone. Fluorochrome labels were injected at the time of surgery and 2 weeks post-surgery to capture bone remodelling over the first 4 weeks. Comprehensive outcome measures included cartilage indentation testing, histological grading, microcomputed tomography and fluorochrome imaging. Findings indicated that needle-puncture devices best preserved the underlying subchondral bone relative to other marrow access approaches. This may relate to the degree of bony compaction occurring with marrow access, as the Kirschner wire approach, which consolidated bone the most, induced the most significant bone damage with marrow stimulation. This study provided basic scientific evidence in support of updated marrow stimulation techniques for preclinical and clinical practice.

Novel Radiographic Indexes for Elbow Stability Assessment: Part A\u2014Cadaveric Validation

IntroductionElbow bony stability relies primarily on the high anatomic congruency between the humeral trochlea and the ulnar greater sigmoid notch. No practical tools are available to distinguish different morphotypes of the proximal ulna and herewith predict elbow stability. The aim of this study was to assess inter-observer reproducibility, evaluate diagnostic performance and determine responsiveness to change after simulated coronoid process fracture for three novel elbow radiographic indexes.MethodsTen fresh-frozen cadaver specimens of upper limbs from human donors were available for this study. Three primary indexes were defined, as well as two derived angles: Trochlear Depth Index (TDI); Posterior Coverage Index (PCI); Anterior Coverage Index (ACI); radiographic coverage angle (RCA); olecranon–diaphisary angle (ODA). Each index was first measured on standardized lateral radiographs and subsequently by direct measurement after open dissection. Finally, a type II coronoid fracture (Regan and Morrey classification) was created on each specimen and both radiographic and open measurements were repeated. All measurements were conducted by two orthopaedic surgeons and two dedicated musculoskeletal radiologists.ResultsAll three indexes showed good or moderate inter-observer reliability and moderate accuracy and precision when compared to the gold standard (open measurement). A significant change between the radiographic TDI and ACI before and after simulated coronoid fracture was observed [TDI: decrease from 0.45 ± 0.03 to 0.39 ± 0.08 (p = 0.035); ACI: decrease from 1.90 ± 0.17 to 1.58 ± 0.21 (p = 0.001)]. As expected, no significant changes were documented for the PCI. Based on these data, a predictive model was generated, able to identify coronoid fractures with a sensitivity of 80% and a specificity of 100%.ConclusionNew, simple and easily reproducible radiological indexes to describe the congruency of the greater sigmoid notch have been proposed. TDI and ACI change significantly after a simulated coronoid fracture, indicating a good responsiveness of these parameters to a pathological condition. Furthermore, combining TDI and ACI in a regression model equation allowed to identify simulated fractures with high sensitivity and specificity. The newly proposed indexes are, therefore, promising tools to improve diagnostic accuracy of coronoid fractures and show potential to enhance perioperative diagnostic also in cases of elbow instability and stiffness.Level of evidenceBasic science study.Clinical relevanceThe newly proposed indexes are promising tools to improve diagnostic accuracy of coronoid fractures as well as to enhance perioperative diagnostic for elbow instability and stiffness.

Postpreparation peri-implant humeral bone density and fixation strength vary based on design in stemless reverse shoulder arthroplasty

Background and HypothesisMorphologic analysis of the proximal humerus has been performed to provide information about regions of best bone quality for stemless implant fixation. However, implant design-related bone analysis regarding primary fixation strength has not been reported. The purpose of this study was to investigate bone volume fraction (BV/TV) and bone mineral density (BMD) in the spatial vicinity of humeral implant fixation and biomechanical performance following placement of two different stemless RSA designs. It was hypothesized that peripheral expandable implant fixation (PEF) would result in residual peri-implant bone with higher BMD and BV/TV and higher fixation strength compared to a central-hexagonal impaction fixation (CHIF) design. MethodsOverall 25 human cadavers were prepped for stemless RSA using either a CHIF (n = 5) or PEF design (n = 20). Micro computed tomography scans were obtained post-preparation to analyze overall BV/TV and BMD in the anchoring region of 2 stemless implant designs. Bone volumes of paired specimens (each group n = 5) were further segmented and divided into three even planar subsections along the implantation direction with four additional radial sectors, each according to their anterior-posterior and medial-lateral direction. Following implantation, biomechanical testing was performed to evaluate ultimate failure load and stiffness of the 2 implants. ResultsPostpreparation paired humeral bone analysis revealed significantly greater residual peri-implant BMD (P< .026) and higher BV/TV for PEF. Overall linear correlation between residual BMD and BV/TV showed good coefficients of determination (R2 > 0.69) with significantly higher bone density for PEF (P= .003). Further division in proximal to distal planar subsections of paired specimens showed overall statistically higher BMD and BV/ TV for PEF (at least P< .002). Except from the posterior sector, BMD and BV/TV of overall and specific radial sectors within planar subvolumes were significantly higher for PEF. Biomechanical testing revealed increased ultimate loads (−818 ± 282 N vs. −535 ± 144 N; P= .081) and stiffness (898 ± 106 N/mm vs. 431 ± 121 N/mm; P< .001) with smaller tilting angles at failure for PEF compared to CHIF. A linear relationship between normalized failure load by the implant size and combined bone parameter (BV/TV*BMD) provided an accuracy in the order of R2 > 0.89 with significantly higher primary stability for PEF (P = .046). ConclusionImplant design in stemless RSA affects residual bone quality in the anchoring region and primary fixation strength. Peripheral implant anchoring along the insertion direction provides significantly higher residual peri-implant BMD and BV/TV to achieve improved primary fixation with a radial expandable anchoring implant compared to a central-hexagonal impacted design. Level of EvidenceBasic Science Study; Anatomy Study; Imaging; Biomechanics

Novel Radiographic Indexes for Elbow Stability Assessment: Part B\u2014Preliminary Clinical Study

IntroductionThe coronoid process plays a key-role in preserving elbow stability. Currently, there are no radiographic indexes conceived to assess the intrinsic elbow stability and the joint congruency. The aim of this study is to present new radiological parameters, which will help assess the intrinsic stability of the ulnohumeral joint and to define normal values of these indexes in a normal, healthy population.MethodsFour independent observers (two orthopaedic surgeons and two radiologists) selected lateral view X-rays of subjects with no history of upper limb disease or surgery. The following radiographic indexes were defined: trochlear depth index (TDI); anterior coverage index (ACI); posterior coverage index (PCI); olecranon–coronoid angle (OCA); radiographic coverage angle (RCA). Inter-observer and intra-observer reproducibility were assessed for each index.Results126 subjects were included. Standardized lateral elbow radiographs (62 left and 64 right elbows) were obtained and analysed. The mean TDI was 0.46 ± 0.06 (0.3–1.6), the mean ACI was 2.0 ± 0.2 (1.6–3.1) and the mean PCI was 1.3 ± 0.1 (1.0–1.9). The mean RCA was 179.6 ± 8.3° (normalized RCA: 49.9 ± 2.3%) and the mean OCA was 24.6 ± 3.7°. The indexes had a high-grade of inter-observer and intra-observer reliability for each of the four observers. Significantly higher values were found for males for TDI, ACI, PCI and RCA.ConclusionThe novel radiological parameters described are simple, reliable and easily reproducible. These features make them a promising tool for radiographic evaluation both for orthopaedic surgeons and for radiologists in the emergency department setting or during outpatient services.Level of evidenceBasic Science Study (Case Series).Clinical relevanceThe novel radiological parameters described are reliable, easily reproducible and become handy for orthopaedic surgeons as well as radiologists in daily clinical practice.

The effect of glenoid lateralization and glenosphere size in reverse shoulder arthroplasty on deltoid load: A biomechanical cadaveric study

PurposeUse of a relatively larger glenosphere with some larger overhang helps to minimize posterior impingement and some degree of glenoid lateralization is also beneficial in reverse shoulder arthroplasty (RSA). The optimal amounts of inferior overhang and lateralization are not agreed upon. The purpose of this in-vitro biomechanical study is to analyze the effect of glenosphere size and glenoid lateralization on deltoid load, focusing on differences in its three distinct heads. MethodsReverse shoulder arthroplasty (DeltaXtend, Fa. Depuy/Synthes) was performed on six cadaveric specimens. The load on each head of the deltoid muscle (spinalis, acromialis, and clavicularis) was measured indirectly by transferring deformation (μm/m) via strain gauges (Fa. Vishay) with stepwise lateralization: +0 mm (subgroup I), +5 mm (subgroup II), +10 mm (subgroup III). Each scenario was done with a 38 mm (group A) and a 42 mm (group B) glenosphere. ResultsIn group A as well in group B, the mean measured deformation in the respective titanium omega increased with lateralization in the clavicular (AI: 119.6 μm/m, AIII: 307.3 μm/m; BI: 173.3 μm/m, BIII: 358.5 μm/m), in the spinal (AI: 85.3 μm/m, AIII: 188.5 μm/m; BI: 138.8 μm/m, BIII 261.2 μm/m) and in the acromial head (AI: 340.5 μm/μ; AIII: 454.2 μm/m; BI: 388.5 μm/m, BIII: 538.8 μm/m). A significant difference between the subgroups in the spinal (p = .048) and clavicular heads (p = .028) was found. The use of a 42 mm glenosphere increased significantly the load in each segment. ConclusionLateralization and glenosphere size increased significantly deltoid muscle loading, especially in the clavicular head. According to these in-vitro data, the high variability in the amount of lateralization influences the soft-tissue balance in reverse shoulder arthroplasty. Level of evidenceBasic science study.

Associations of dietary and lifestyle oxidative balance scores with mortality risk among older women: the Iowa Women's Health Study.

Substantial basic science evidence suggests that oxidative stress may play a role in aging-related health outcomes, including cardiovascular diseases (CVD) and cancer, and oxidative stress markers were linked with all-cause and cause-specific mortality in epidemiologic studies. However, the associations of many individual dietary and lifestyle anti-/pro-oxidant exposures with mortality are inconsistent. Oxidative balance scores (OBS) that incorporated multiple dietary and lifestyle factors were previously developed and reported to reflect the collective oxidative effects of multiple exposures. We investigated associations of 11-component dietary and 4-component (physical activity, adiposity, alcohol, and smoking) lifestyle OBS (higher scores were considered more anti-oxidative) with all-cause and cause-specific mortality among women 55-69years of age at baseline in the prospective Iowa Women's Health Study (1986-2012). We assessed OBS-mortality associations using multivariable Cox proportional hazards regression. Of the 34,137 cancer-free women included in the analytic cohort, 18,058 died (4521 from cancer, and 6825 from CVD) during a mean/median 22.0/26.1 person-years of follow-up. Among participants in the highest relative to the lowest lifestyle OBS quintiles, the adjusted hazards ratios and their 95% confidence intervals for all-cause, all-cancer, and all-CVD mortality were 0.50 (0.48, 0.53), 0.47 (0.43, 0.52), and 0.54 (0.50, 0.58) (all Ptrend < 0.001), respectively. The associations of the dietary OBS with mortality were close to null. Our findings, combined with results from previous studies, suggest that a predominance of antioxidant over pro-oxidant lifestyle exposures may be associated with lower all-cause, all-CVD, and all-cancer mortality risk.