Research Toward Understanding the Benefits and Limitations of Orthotic Use To Improve Mobility and Balance for Individuals With Neuropathic Conditions.

Background: Walking is a vital activity often compromised in individuals with neuropathic conditions. Charcot-Marie-Tooth (CMT) disease and Cerebral Palsy (CP) are two common neurodevelopmental disabilities affecting gait, predisposing to the risk of falls. With guiding scientific evidence limited, there is a critical need to better understand how surgical correction affects mobility, balance confidence, and gait compared to ankle foot orthosis (AFO) bracing. A systematic approach will enable rigorous collaborative research to advance clinical care. Methods: Key elements of this vision include 1) prospective studies in select patient cohorts to systematically compare conservative vs. surgical management, 2) objective laboratory-based evaluation of patient mobility, balance, and gait using reliable methods, and 3) use of patient-centric outcome measures related to health and mobility. Results: Valid and reliable standardized tests of physical mobility and balance confidence have been described in the literature. They include 1) the four-square step test, a widely used test of balance and agility that predicts fall risk, 2) the self-selected walking velocity, a measure of general mobility able to detect function change with orthosis use, and 3) the activity specific balance confidence scale, a survey instrument that assesses an individual's level of balance confidence during activity. Additionally, motion capture and ground reaction force data can be used to evaluate whole-body motion and loading, with discriminative biomechanical measures including toe clearance during the swing phase of gait, plantarflexion at 50% of swing, peak ankle plantarflexor moment, and peak ankle push-off power. Conclusion: The tools needed to support evidence-based practice and inform clinical decision making in these challenging patient populations are all available. Research must now be conducted to better understand the potential benefits and limitations of AFO use in the context of mobility and balance during gait for individuals with neuropathic conditions, particularly relative to those offered by surgical correction. Clinical Relevance: Following this path of research will provide comparative baseline data on mobility, balance confidence, and gait that can be used to inform an objective criterion-based approach to AFO prescription and the impact of surgical intervention.

Accuracy of volumetric bone mineral density measurement in weight bearing, cone beam computed tomography.

BACKGROUND: Weight bearing computed tomography (WBCT) utilizes cone beam CT technology to provide assessments of lower limb joint structures while they are functionally loaded. Grey-scale values indicative of X-ray attenuation that are output from cone beam CT are challenging to calibrate, and their use for bone mineral density (BMD) measurement remains debatable. To determine whether WBCT can be reliably used for cortical and trabecular BMD assessment, we sought to establish the accuracy of BMD measurements at the knee using modern WBCT by comparing them to measurements from conventional CT. METHODS: A hydroxyapatite phantom with three inserts of varying densities was used to systematically quantify signal uniformity and BMD accuracy across the acquisition volume. We evaluated BMD in vivo (n = 5, female) using synchronous and asynchronous calibration techniques in WBCT and CT. To account for variation in attenuation along the height (z-axis) of acquisition volumes, we tested a height-dependent calibration approach for both WBCT and CT images. RESULTS: Phantom BMD measurement error in WBCT was as high as 15.3% and consistently larger than CT (up to 5.6%). Phantom BMD measures made under synchronous conditions in WBCT improved measurement accuracy by up to 3% but introduced more variability in measured BMD. We found strong correlations (R = 0.96) as well as wide limits of agreement (-324 mgHA/cm3 to 183 mgHA/cm3) from Bland-Altman analysis between WBCT and CT measures in vivo that were not improved by height-dependent calibration. CONCLUSION: Whilst BMD accuracy from WBCT was found to be dependent on apparent density, accuracy was independent of the calibration technique (synchronous or asynchronous) and the location of the measurement site within the field of view. Overall, we found strong correlations between BMD measures from WBCT and CT and in vivo measures to be more accurate in trabecular bone regions. Importantly, WBCT can be used to distinguish between anatomically relevant differences in BMD, however future work is necessary to determine the repeatability and sensitivity of BMD measures in WBCT.

Foot offloading associated with carbon fiber orthosis use: A pilot study.

BACKGROUND: Traumatic lower limb injuries can result in chronic pain. Orthotic interventions are a leading conservative approach to reduce pain, manage loading, and protect the foot. Robust carbon fiber custom dynamic orthoses (CDOs) designed for military service members have been shown to reduce foot loading. However, the effect of carbon fiber orthosis design, including designs widely used in the civilian sector, on foot loading is unknown. RESEARCH QUESTION: Determine if carbon fiber orthoses alter foot loading during gait. METHODS: Loadsol insoles were used to measure peak forces and force impulse acting on the forefoot, midfoot, hindfoot, and total foot. Nine healthy, able-bodied individuals participated. Force impulse was quantified as cumulative loading throughout stance phase. Participants walked without an orthosis and with three carbon fiber orthoses of differing designs: a Firm stiffness CDO, a Moderate stiffness CDO, and a medial and lateral strut orthosis (MLSO). RESULTS: There were significant main effects of orthosis condition on peak forefoot forces as well as forefoot and hindfoot force impulse. Peak forefoot forces were significantly lower in the Moderate and Firm CDOs compared to no orthosis and MLSO. Compared to walking without an orthosis, forefoot force impulse was significantly lower and hindfoot force impulse was significantly greater in all carbon fiber orthoses. Additionally, hindfoot force impulse in the Firm CDO was significantly higher than in the MLSO and Moderate CDO. SIGNIFICANCE: The three carbon fiber orthosis designs differed regarding foot loading, with more robust orthoses providing greater forefoot offloading. Orthosis-related changes in forefoot loading suggest that carbon fiber orthoses could reduce loading-associated pain during gait. However, increased hindfoot force impulse suggests caution should be used when considering carbon fiber orthoses for individuals at risk of skin breakdown with repetitive loading.

Distal femur fractures: basic science and international perspectives.

Distal femur fractures are challenging injuries to manage, and complication rates remain high. This article summarizes the international and basic science perspectives regarding distal femoral fractures that were presented at the 2022 Orthopaedic Trauma Association Annual Meeting. We review a number of critical concepts that can be considered to optimize the treatment of these difficult fractures. These include biomechanical considerations for distal femur fixation constructs, emerging treatments to prevent post-traumatic arthritis, both systemic and local biologic treatments to optimize nonunion management, the relative advantages and disadvantages of plate versus nail versus dual-implant constructs, and finally important factors which determine outcomes. A robust understanding of these principles can significantly improve success rates and minimize complications in the treatment of these challenging injuries.

Influence of sidewall retention and interference fit in total ankle replacement on implant-bone micromotion: A finite element study.

The success of uncemented total ankle replacement (TAR) is linked to initial stability because bony ingrowth depends upon limited early micromotion. Tibial implant design fixation features resist micromotion aided by bony sidewall retention and interference fit. Our goal was to investigate factors influencing implant-bone micromotion in TAR. Two TAR tibial components were virtually inserted into CT-derived computer models of two distal tibias from patients with end-stage ankle arthritis. Density-based inhomogeneous material assignment was used to model bone compaction during press-fit. Finite element analysis (FEA) was used to simulate three fixation cases: (1) no sidewalls + line-to-line fit, (2) sidewalls + line-to-line fit, and (3) sidewalls + 50, 100, or 200 µm interference fit. Kinetic profiles from the stance phase of gait were simulated and micromotions computed from FEA output. Without sidewalls or interference fit, micromotions were largest in early and late stance, with largest micromotions (averaging ~150-250 µm) observed near heel strike. Micromotions decreased 39%-62% when sidewalls were retained. When interference fit was also modeled, micromotions decreased another 37%-61% to ~10 µm. Micromotion differences between patients persisted with sidewall retention but largely disappeared with interference fit. This study presents new insights into the effects of TAR fixation features on implant-bone micromotion. Stability appeared to be influenced by surrounding bone quality, but this influence was greatly diminished when interference fit was introduced. More complete understanding of TAR implant features and performance is needed, but our results show the importance of bone quality and interference fit in the stability of uncemented TAR.

Fluoroscopic image-based behavior analysis can objectively explain subjective expert assessment of wire navigation skill.

Psychomotor skill and decision-making efficiency in surgical wire navigation can be objectively evaluated by analysis of intraoperative fluoroscopic image sequences. Prior work suggests that such image-based behavior analysis of operating room (OR) performance can predict performer experience level (R2 = 0.62) and agree with expert opinion (the current standard) on the quality of a final implant construct (R2 = 0.59). However, it is unclear how objective image-based evaluation compares with expert assessments for entire technical OR performances. This study examines the relationships between three key variables: (1) objective image-based criteria, (2) expert opinions, and (3) performing surgeon experience level. A paired-comparison survey of seven experts, based upon eight OR fluoroscopic wire navigation image sequences, shows that the experts' preferences are best explained by objective metrics that reflect psychomotor and decision-making behaviors which are counter-productive to successful implant placement, like image count (R2 = 0.83) and behavior tally (R2 = 0.74). One such behavior, adjustments away from goal, uniquely correlated well with all three key variables: a fluoroscopic image-based analysis composite score (R2 = 0.40), expert consensus (R2 = 0.76), and performer experience (R2 = 0.41). These results confirm that experts view less efficient technical behavior as indicative of lesser technical proficiency. While expert assessments of technical skill were reliable and consistent, neither individual nor consensus expert opinion appears to correlate with performer experience (R2 = 0.11).

A Dedicated Simulator Training Curriculum Improves Resident Performance in Surgical Management of Pediatric Supracondylar Humerus Fractures.

Background: The primary goal of including simulation in residency training is to improve technical skills while working outside of the operating room. Such simulation-related skill improvements have seldom been measured in the operating room. This is largely because uncontrolled variables, such as injury severity, patient comorbidity, and anatomical variation, can bias evaluation of an operating surgeon's skill. In this study, performance during the wire navigation phase of pediatric supracondylar humerus fracture fixation was quantitatively compared between 2 groups of orthopaedic residents: a standard training group consisting of residents who participated in a single simulator session of wire navigation training and an expanded training group consisting of residents who participated in a dedicated multifaceted wire navigation simulation training curriculum. Methods: To evaluate performance in the operating room, the full sequence of fluoroscopic images collected during wire navigation was quantitatively analyzed. Objective performance metrics included number of fluoroscopic images acquired, duration from placement of the first wire to that of the final wire, and wire spread at the level of the fracture. These metrics were measured from 97 pediatric supracondylar humerus fracture pinning surgeries performed by 28 different orthopaedic residents. Results: No differences were observed between the groups for wire spread in the final fluoroscopic images (t(94) = 0.75, p = 0.45), an important clinical objective of the surgery. Residents who received the expanded simulator training used significantly fewer fluoroscopic images (mean of 46 vs. 61 images, t(85) = 2.25, p < 0.03) and required less time from first to final wire placement (mean of 11.2 vs. 14.9 minutes, t(83) = 2.53, p = 0.013) than the standard training group. A post hoc review of Accreditation Council for Graduate Medical Education case logs for 24 cases from the standard training group and for 21 cases from the expanded training group indicated that, at the time of surgeries, residents who received expanded training had completed fewer comparable cases than residents in the standard training group (mean of 13 vs. 21, t(42) = 2.40 p = 0.02). Further regression analysis indicated that the expanded simulator training produced an effect comparable with that associated with completing 10.5 similar surgical case experiences. Conclusions: This study demonstrates that training on a wire navigation simulator can lead to improved performance in the operating room on a critical skill for all orthopaedic residents. By taking fewer images and less time while maintaining sufficient pin spread, simulator-trained residents were objectively measured to have improved performance in comparison with residents who had not participated in the pediatric elbow simulator curriculum. Clinical Relevance: As programs aim to provide safe and effective training for critical orthopaedic skills such as pinning a pediatric elbow, this study demonstrates a simulator curriculum that has demonstrated the transfer of skill from a learning environment to the operating room.

Establishing Construct Validity of a Novel Simulator for Guide Wire Navigation in Antegrade Femoral Intramedullary Nailing.

Background: Antegrade femoral intramedullary nailing (IMN) is a common orthopedic procedure that residents are exposed to early in their training. A key component to this procedure is placing the initial guide wire with fluoroscopic guidance. A simulator was developed to train residents on this key skill, building off an existing simulation platform originally developed for wire navigation during a compression hip screw placement. The objective of this study was to assess the construct validity of the IMN simulator. Methods: Thirty orthopedic surgeons participated in the study: 12 had participated in fewer than 10 hip fracture or IMN related procedures and were categorized as novices; 18 were faculty, categorized as experts. Both cohorts were instructed on the goal of the task, placing a guide wire for an IM nail, and the ideal wire position reference that their wire placement would be graded against. Participants completed 2 assessments with the simulator. Performance was graded on the distance from the ideal starting point, distance from the ideal end point, wire trajectory, duration, fluoroscopy image count, and other elements of surgical decision making. A two-way ANOVA analysis was used to analyze the data looking at experience level and trial number. Results: The expert cohort performed significantly better than the novice cohort on all metrics but one (overuse of fluoroscopy). The expert cohort had a more accurate starting point and completed the task while using fewer images and less overall time. Conclusion: This initial study shows that the IMN application of a wire navigation simulator demonstrates good construct validity. With such a large cohort of expert participants, we can be confident that this study captures the performance of active surgeons today. Implementing a training curriculum on this simulator has the potential to increase the performance of the novice level residents prior to their operating on a vulnerable patient. Level of Evidence: III.

Current Challenges in Chronic Ankle Instability: Review and Perspective.

Chronic ankle instability (CAI) is common, disabling, and represents a significant socioeconomic burden. Current treatment options are not adequately efficacious. CAI is multifaceted, yet it is commonly addressed in terms of either mechanical instability or functional impairment. Both are inherently linked. Basic research must be conducted to foster reliable translational research encompassing both mechanical and functional aspects. A review was conducted to identify CAI risk factors for inclusion in future studies, and we offer here opinions and perspectives for future research.

Injury-related cell death and proteoglycan loss in articular cartilage: Numerical model combining necrosis, reactive oxygen species, and inflammatory cytokines.

Osteoarthritis (OA) is a common musculoskeletal disease that leads to deterioration of articular cartilage, joint pain, and decreased quality of life. When OA develops after a joint injury, it is designated as post-traumatic OA (PTOA). The etiology of PTOA remains poorly understood, but it is known that proteoglycan (PG) loss, cell dysfunction, and cell death in cartilage are among the first signs of the disease. These processes, influenced by biomechanical and inflammatory stimuli, disturb the normal cell-regulated balance between tissue synthesis and degeneration. Previous computational mechanobiological models have not explicitly incorporated the cell-mediated degradation mechanisms triggered by an injury that eventually can lead to tissue-level compositional changes. Here, we developed a 2-D mechanobiological finite element model to predict necrosis, apoptosis following excessive production of reactive oxygen species (ROS), and inflammatory cytokine (interleukin-1)-driven apoptosis in cartilage explant. The resulting PG loss over 30 days was simulated. Biomechanically triggered PG degeneration, associated with cell necrosis, excessive ROS production, and cell apoptosis, was predicted to be localized near a lesion, while interleukin-1 diffusion-driven PG degeneration was manifested more globally. Interestingly, the model also showed proteolytic activity and PG biosynthesis closer to the levels of healthy tissue when pro-inflammatory cytokines were rapidly inhibited or cleared from the culture medium, leading to partial recovery of PG content. The numerical predictions of cell death and PG loss were supported by previous experimental findings. Furthermore, the simulated ROS and inflammation mechanisms had longer-lasting effects (over 3 days) on the PG content than localized necrosis. The mechanobiological model presented here may serve as a numerical tool for assessing early cartilage degeneration mechanisms and the efficacy of interventions to mitigate PTOA progression.

Biomechanical guidance can improve accuracy of reduction for intra-articular tibia plafond fractures and reduce joint contact stress.

Articular fracture malreduction increases posttraumatic osteoarthritis (PTOA) risk by elevating joint contact stress. A new biomechanical guidance system (BGS) that provides intraoperative assessment of articular fracture reduction and joint contact stress based solely on a preoperative computed tomography (CT) and intraoperative fluoroscopy may facilitate better fracture reduction. The objective of this proof-of-concept cadaveric study was to test this premise while characterizing BGS performance. Articular tibia plafond fractures were created in five cadaveric ankles. CT scans were obtained to provide digital models. Indirect reduction was performed in a simulated operating room once with and once without BGS guidance. CT scans after fixation provided models of the reduced ankles for assessing reduction accuracy, joint contact stresses, and BGS accuracy. BGS was utilized 4.8 ± 1.3 (mean ± SD) times per procedure, increasing operative time by 10 min (39%), and the number of fluoroscopy images by 31 (17%). Errors in BGS reduction assessment compared to CT-derived models were 0.45 ± 0.57 mm in translation and 2.0 ± 2.5° in rotation. For the four ankles that were successfully reduced and fixed, associated absolute errors in computed mean and maximum contact stress were 0.40 ± 0.40 and 0.96 ± 1.12 MPa, respectively. BGS reduced mean and maximum contact stress by 1.1 and 2.6 MPa, respectively. BGS thus improved the accuracy of articular fracture reduction and significantly reduced contact stress. Statement of Clinical Significance: Malreduction of articular fractures is known to lead to PTOA. The BGS described in this work has potential to improve quality of articular fracture reduction and clinical outcomes for patients with a tibia plafond fracture.

The Inflamma-type: a patient phenotype characterized by a dysregulated inflammatory response after lower extremity articular fracture.

Synovial fluid was collected from 113 patients who had suffered tibial plateau (n = 48), tibial plafond (n = 29), or rotational ankle fractures (n = 36). Concentrations of IL-1ß, IL-1RA, IL-6, IL-8, IL-10, and MMP-1, -3, and -13 were quantified using multiplex assays. A cluster analysis of synovial fluid biomarker concentrations was performed. Patient demographics, fracture type, Injury Severity Score (ISS), Charlson Comorbidity Index (CCI), and biomarker concentrations were compared between clusters. A subset of patients demonstrated a dysregulated inflammatory response after articular fracture including elevated pro-inflammatory cytokines and degradative enzymes previously linked to the development of post-traumatic osteoarthritis.

An Objective Computational Method to Quantify Ankle Osteoarthritis From Low-Dose Weightbearing Computed Tomography.

Background: The treatment of ankle osteoarthritis (OA) varies depending on the severity and distribution of the associated joint degeneration. Disease staging is typically based on subjective grading of appearance on conventional plain radiographs, with reported subpar reproducibility and reliability. The purpose of this study was to develop and describe computational methods to objectively quantify radiographic changes associated with ankle OA apparent on low-dose weightbearing CT (WBCT). Methods: Two patients with ankle OA and 1 healthy control who had all undergone WBCT of the foot and ankle were analyzed. The severity of OA in the ankle of each patient was scored using the Kellgren-Lawrence (KL) classification using plain radiographs. For each ankle, a volume of interest (VOI) was centered on the tibiotalar joint. Initial computation analysis used WBCT image intensity (Hounsfield units [HU]) profiles along lines perpendicular to the subchondral bone/cartilage interface of the distal tibia extending across the entire VOI. Graphical plots of the HU distributions were generated and recorded for each line. These plots were then used to calculate the joint space width (JSW) and HU contrast. Results: The average JSW was 3.89 mm for the control ankle, 3.06 mm for mild arthritis (KL 2), and 1.57 mm for severe arthritis (KL 4). The average HU contrast was 72.31 for control, 62.69 for mild arthritis, and 33.98 for severe arthritis. The use of 4 projections at different locations throughout the joint allowed us to visualize specifically which quadrants have reduced joint space width and contrast. Conclusion: In this technique report, we describe a novel methodology for objective quantitative assessment of OA using JSW and HU contrast. Clinical Relevance: Objective, software-based measurements are generally more reliable than subjective qualitative evaluations. This method may offer a starting point for the development of a more robust OA classification system or deeper understanding of the pathogenesis and response to ankle OA treatment.

Syndesmosis Malposition Assessed on Weight-Bearing CT Is Common After Operative Fixation of Intra-articular Distal Tibia Plafond Fracture.

OBJECTIVES: To evaluate reliability of measurement techniques for syndesmosis position after operative fixation of distal tibia plafond fracture on weight-bearing computed tomography (WBCT), identify risk factors for syndesmosis malposition, and determine if syndesmosis malposition is associated with higher pain and lower physical function. DESIGN: Prospective cohort study. SETTING: Three Level 1 trauma centers. PARTICIPANTS: Twenty-six subjects who underwent open reduction and internal fixation of distal tibia plafond fractures with bilateral ankle WBCT 1 year or greater after injury were included in the study. INTERVENTION: Operative fixation of distal tibia plafond fracture. MAIN OUTCOME MEASUREMENT: Fibula position in the tibia incisura, injury characteristics, and patient-reported outcomes were the main outcome measurements. RESULTS: Interrater reliability for syndesmosis position measurements were excellent for the Phisitkul technique on both injured and healthy ankles (intraclass correlation coefficients [ICCs]: 0.93-0.98). The Nault technique demonstrated moderate-to-excellent interrater reliability (ICCs: 0.67-0.98), apart from the angle of rotation measurement (ICCs: 0.18-0.67). Sixteen of 26 subjects (62%) had syndesmosis malposition defined as >2 mm difference comparing the tibial-fibular relationship in injured and uninjured ankles using these 2 methods. Patients with syndesmosis malposition reported lower Foot and Ankle Ability Measure: Activities of Daily Living scores; other recorded patient-reported outcomes were not significantly different. CONCLUSIONS: Measurement techniques for syndesmosis position on WBCT were reliable after operative fixation of distal tibia plafond fracture. Syndesmosis malposition is common after these injuries and predicted impaired physical function. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Summary Report of the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society's Symposium on Targets for Osteoarthritis Research: Part 1: Epidemiology, Pathophysiology, and Current Imaging Approaches.

This first of a 2-part series of articles recounts the key points presented in a collaborative symposium sponsored jointly by the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society with the intent to survey the state of scientific knowledge related to incidence, diagnosis, pathologic mechanisms, and injection treatment options for osteoarthritis (OA) of the foot and ankle. A meeting was held virtually on December 3, 2021. A group of experts were invited to present brief synopses of the current state of knowledge and research in this area. Part 1 overviews areas of epidemiology and pathophysiology, current approaches in imaging, diagnostic and therapeutic injections, and genetics. Opportunities for future research are discussed. The OA scientific community, including funding agencies, academia, industry, and regulatory agencies, must recognize the needs of patients that suffer from arthritis of foot and ankle. The foot and ankle contain a myriad of interrelated joints and tissues that together provide a critical functionality. When this functionality is compromised by OA, significant disability results, yet the foot and ankle are generally understudied by the research community. Level of Evidence: Level V - Review Article/Expert Opinion.

Summary Report of the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society's Symposium on Targets for Osteoarthritis Research: Part 2: Treatment Options.

This second of a 2-part series of articles recounts the key points presented in a collaborative symposium sponsored jointly by the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society with the intent to survey current treatment options for osteoarthritis (OA) of the foot and ankle. A meeting was held virtually on December 10, 2021. A group of experts were invited to present brief synopses of the current state of knowledge and research in this area. Topics were chosen by meeting organizers, who then identified and invited the expert speakers. Part 2 overviews the current treatment options, including orthotics, non-joint destructive procedures, as well as arthroscopies and arthroplasties in ankles and feet. Opportunities for future research are also discussed, such as developments in surgical options for ankle and the first metatarsophalangeal joint. The OA scientific community, including funding agencies, academia, industry, and regulatory agencies, must recognize the importance to patients of addressing the foot and ankle with improved basic, translational, and clinical research. Level of Evidence: Level V, review article/expert opinion.

Minimally Trained Analysts Can Perform Fast, Objective Assessment of Orthopedic Technical Skill from Fluoroscopic Images.

Skill assessment in orthopedics has traditionally relied on subjective impressions from a supervising surgeon. The feedback derived from these tools may be limited by bias and other practical issues. Objective analysis of intraoperative fluoroscopic images offers an inexpensive, repeatable, and precise assessment strategy without bias. Assessors generally refrain from using the scores of images obtained throughout the operation to evaluate skill for practical reasons. A new system was designed to facilitate rapid analysis of this fluoroscopy via minimally trained analysts. Four expert and four novice analysts independently measured one objective metric for skill using both a custom analysis software and a commercial alternative. Analysts were able to measure the objective metric three times faster when using the custom software, and without a practical difference in accuracy in comparison to the expert analysts using the commercial software. These results suggest that a well-designed fluoroscopy analysis system can facilitate inexpensive, reliable, and objective assessment of surgical skills.

Return of Scapulohumeral Rhythm in Patients After Reverse Shoulder Arthroplasty: A Midterm Stereoradiographic Imaging Analysis.

Background: Reverse shoulder arthroplasty (RSA) is associated with high rates of midterm complications including scapular notching, implant wear, and mechanical impingement. Scapulo-humeral rhythm (SHR), described by Codman in the 1920's, is defined as the ratio of glenohumeral motion to scapulothoracic motion. SHR is used as an indicator of shoulder dysfunction, as alterations in SHR can have profound implications on shoulder biomechanics. The determination of SHR can be hindered by soft-tissue motion artifacts and high radiation burdens associated with traditional surface marker or fluoroscopic analysis. EOS low dose stereoradiographic imaging analysis utilizing 3D model construction from a 2D X-ray series may offer an alternative modality for characterizing SHR following RSA. Methods: Patients (n=10) underwent an EOS imaging analysis to determine SHR at six and twelve months post-RSA. Leveraging 3D models of the implants, 2D/3D image registration methods were used to calculate relative glenohumeral and scapulothoracic positioning at 60, 90 and 120° of shoulder elevation. Subject-specific SHR curves were assessed and midterm changes in post-RSA SHR associated with follow-up time and motion phase were evaluated. Pearson correlations assessed associations between patient-specific factors and post-RSA SHR. Results: Mean post-RSA SHR was 0.81:1 across subjects during the entire midterm postoperative period. As a cohort, post-RSA SHR was more variable for 60-90° of shoulder motion. SHR for 90-120° of motion decreased (0.43:1) at twelve months post-RSA. Post-RSA SHR could be categorized using three relative motion curve patterns, and was not strongly associated with demographic factors such as BMI. 50% of subjects demonstrated a different SHR relative motion curve shape at twelve months post-RSA, and SHR during the 90120° of motion was found to generally decrease at twelve months. Conclusion: Midterm post-RSA SHR was successfully evaluated using EOS technology, revealing lower SHR values (i.e., greater scapulothoracic motion) compared to normal values reported in the literature. SHR continued to change for some subjects during the midterm post-RSA period, with the greatest change during 90-120° of shoulder motion. Study findings suggest that future post RSA rehabilitation efforts to address elevated scapulothoracic motion may benefit from being patient-specific in nature and targeting scapular stabilization during 90-120° of shoulder motion. Level of Evidence: IV.

Longitudinal Relationship Between Tibiofemoral Contact Stress at Baseline and Worsening of Knee Pain Over 84 Months in the Multicenter Osteoarthritis Study.

OBJECTIVE: The aim of the study was to determine whether tibiofemoral contact stress predicts risk for worsening knee pain over 84 ms in adults aged 50-79 yrs with or at elevated risk for knee osteoarthritis. DESIGN: Baseline tibiofemoral contact stress was estimated using discrete element analysis. Other baseline measures included weight, height, hip-knee-ankle alignment, Kellgren-Lawrence grade, and Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. Logistic regression models assessed the association between baseline contact stress and 84-mo worsening of Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. RESULTS: Data from the dominant knee (72.6% Kellgren-Lawrence grade 0/1 and 27.4% Kellgren-Lawrence grade ≥ 2) of 208 participants (64.4% female, mean ± SD body mass index = 29.6 ± 5.1 kg/m 2 ) were analyzed. Baseline mean and peak contact stress were 3.3 ± 0.9 and 9.4 ± 4.3 MPa, respectively. Forty-seven knees met the criterion for worsening pain. The highest tertiles in comparison with the lowest tertiles of mean (odds ratio [95% confidence interval] = 2.47 [1.03-5.95], P = 0.04) and peak (2.49 [1.03-5.98], P = 0.04) contact stress were associated with worsening pain at 84 mos, after adjustment for age, sex, race, clinic site, and baseline pain. Post hoc sensitivity analyses including adjustment for body mass index and hip-knee-ankle alignment attenuated the effect. CONCLUSIONS: These findings suggest that elevated tibiofemoral contact stress can predict the development of worsening of knee pain.

Failure of Orthopaedic Residents to Voluntarily Participate in a Laboratory Skills Training.

INTRODUCTION: Arthroscopy simulation is increasingly used in orthopaedic residency training. The implementation of a curriculum to accommodate these new training tools is a point of interest. We assessed the use of a high-fidelity arthroscopy simulator in a strictly voluntary curriculum to gauge resident interest and educational return. METHODS: Fifty-eight months of simulator use data were collected from a single institution to analyze trends in resident use. Comparable data from two additional residency programs were analyzed as well, for comparison. Orthopaedic residents were surveyed to gauge interest in continued simulation training. RESULTS: Average annual simulator use at the study institution was 27.7 hours (standard deviation = 26.8 hours). Orthopaedic residents spent an average of 1.7 hours practicing on the simulation trainer during the observation period. A total of 21% of residents met or exceeded a minimum of 3 hours of simulation time required for skill improvement defined by literature. Most (86%) of the residents agreed that the simulator in use should become a mandated component of a junior resident training. CONCLUSION: Although surgical simulation has a role in orthopaedic training, voluntary simulator use is sporadic, resulting in many residents not receiving the full educational benefits of such training. Implementation of a mandated simulation training curriculum is desired by residents and could improve the educational return of surgical simulators in residency training.