The impact of prior authorization review on orthopaedic subspecialty care: a prospective multicenter analysis.

BACKGROUND: Prior authorization review (PAR), in the United States, is a process that was initially intended to focus on hospital admissions and costly high-acuity care. Over time, payors have broadened the scope of PAR to include imaging studies, prescriptions, and routine treatment. The potential detrimental effect of PAR on health care has recently been brought into the limelight, but its impact on orthopedic subspecialty care remains unclear. This study investigated the denial rate, the duration of care delay, and the administrative burden of PAR on orthopedic subspecialty care. METHODS: A prospective, multicenter study was performed analyzing the PAR process. Orthopedic shoulder and/or sports subspecialty practices from 6 states monitored payor-mandated PAR during the course of providing routine patient care. The insurance carrier (traditional Medicare, managed Medicare, Medicaid, commercial, worker's compensation, or government payor [ie, Tricare, Veterans Affairs]), location of service, rate of approval or denial, time to approval or denial, and administrative time required to complete process were all recorded and evaluated. RESULTS: Of 1065 total PAR requests, we found a 1.5% (16/1065) overall denial rate for advanced imaging or surgery when recommended by an orthopedic subspecialist. Commercial and Medicaid insurance resulted in a small but statistically significantly higher rate of denial compared to traditional Medicare, managed Medicare, worker's compensation, or governmental insurance (P < .001). The average administrative time spent on a single PAR was 19.5 minutes, and patients waited an average of 2.2 days to receive initial approval. Managed Medicare, commercial insurance, worker's compensation, and Medicaid required approximately 3-4 times more administrative time to process a PAR than to traditional Medicare or other governmental insurance (P < .001). After controlling for the payor, we identified a significant difference in approval or denial based on geographic location (P < .001). An appeal resulted in a relatively low rate of subsequent denial (20%). However, approximately a third of all appeals remained in limbo for 30 days or more after the initial request. CONCLUSIONS: This is the largest prospective analysis to date of the impact of PAR on orthopedic subspecialty care in the United States. Nearly all PAR requests are eventually approved when recommended by orthopedic subspecialists, despite requiring significant resource use and delaying care. Current PAR practices constitute an unnecessary process that increases administrative burden and negatively impacts access to orthopedic subspecialty care. As health care shifts to value-based care, PAR should be called into question, as it does not seem to add value but potentially negatively impacts cost and timeliness of care.

Risk of Recall Associated With Modifications to High-risk Medical Devices Approved Through US Food and Drug Administration Supplements.

Importance: High-risk medical devices approved by the US Food and Drug Administration (FDA) can undergo modifications to their original premarket approval (PMA) via 1 of 5 types of supplements. Only panel track supplements (approximately 1%) require clinical data for approval. The association between device modifications and risk to patient safety has not previously been analyzed. Objective: To determine the association between PMA supplements and the risk of any device recall and high-risk (class 1) recall. Design, Setting, and Participants: In this cohort study, the FDA database was queried for original devices approved via PMA from January 1, 2008, through December 31, 2019. Supplement and recall data were obtained for these devices from January 1, 2008, through December 31, 2021, giving a minimum 2-year follow-up after initial approval. Data were analyzed from July 6 to August 6, 2022. Retrospective, time-to-event analysis investigated the association between the number and type of supplements and risk of recall. Exposures: Supplements submitted by manufacturers for FDA approval to modify devices. Main Outcomes and Measures: A mixed-effects Cox proportional hazards regression model with frailty terms was used, modeling device recall as an outcome variable during the observation period. A second model was performed for class 1 (high-risk) recall. Explanatory variables are the number of supplements, number of panel track supplements, and cardiovascular devices. Multivariable analysis was performed to identify independent risk factors for recall with hazard ratios (HRs) as the main end point. Results: A total of 373 original PMA devices with 10 776 associated supplements were included in the analysis. A median 2.5 (IQR, 1.2-5.0) supplements per device were approved annually. Cardiovascular devices contributed 138 supplements (37.0%), followed by microbiology with 45 (12.1%). No other specialty contributed more than 10%. Multivariable analysis demonstrated that each increase of 1 supplement per year was associated with increased risk of recall (HR, 1.28 [95% CI, 1.15-1.44]; P < .001). For class 1 recall, increased number of supplements (HR, 1.32 [95% CI, 1.06-1.64]; P = .01) and cardiovascular vsnoncardiovascular classification of devices (HR, 3.51 [95% CI, 1.15-10.72]; P = .03) were significantly associated with an increased risk of recall. Conclusions and Relevance: The findings of this cohort study suggest that PMA supplements are associated with an approximately 30% increased risk of any recall and class 1 recall. The FDA processes for approving modifications to high-risk medical devices should be reevaluated to optimize patient safety and public health.

Risk of Recall for Total Joint Arthroplasty Devices Over 10 Years.

BACKGROUND: Orthopaedic devices comprise nearly 20% of devices on the market and 12% to 20% of these devices undergo a recall within 10 years. More than 95% of these devices are approved without supporting clinical data through the Food and Drug Administration's 510(k) pathway. The risk of recall of orthopaedic arthroplasty devices approved through the 510(k) pathway has not been previously studied. METHODS: The FDA 510(k) database was queried for orthopaedic devices approved between January 01, 2008 and December 31, 2018 and subsequently codified to hip and knee arthroplasty devices using product codes. The database included 904 arthroplasty devices during the study period, with hip and knee making up 53.7% (485) and 46.3% (419) of devices, respectively. Information regarding numbers, dates, and reasons for recall were recorded. Cumulative incidence function was conducted to compare the risk of recall between hip and knee arthroplasty. RESULTS: In total, 94 (19.4%) hip and 85 (20.3%) knee devices were recalled. The hazard of recall by 10 years for hip and knee arthroplasty devices was approximately 24%, with no statistical differences between each region. The most common causes of recall were process control and device design, accounting for 29.6% and 26.3% of recalls, respectively, with no significant difference between study groups. CONCLUSION: The risk of recall for arthroplasty devices is more than that previously understood. Improved postmarket surveillance strategies along with increased physician participation in detecting and reporting device safety issues are necessary to strengthen patient safety.

Decision-making in the treatment of radial head fractures: Delphi methodology.

BACKGROUND: The treatment of partially displaced radial head fractures is determined not only by the type of fracture but also by patient characteristics such as age, occupation, hand dominance, mechanism of injury, and concomitant injuries and comorbidities. The goal of this study was to employ the Delphi method to achieve consensus on the management of patients with radial head fractures, utilizing the experience of the ASES Elbow Fracture-Dislocation Multicenter Study Group and Mayo Elbow Club surgeons. METHODS: The initial survey was sent to participants, which included consent to participate in the study and questions about their experience, knowledge, and interest in participating in the Delphi method. We used both open-ended and category-based questions. The second questionnaire generated 76 variables, and individual questions with mean Likert ratings of <2.0 or >4.0 were deemed significant and merged to form multifactorial clinical scenarios relating to both nonoperative and operative management, respectively. RESULTS: Of the surgeons who responded to the questionnaire, 64% were from the United States, while the remainder were from overseas practices. Years in practice on average were 12.4 years (range, 1-40). Seven of the 76 factors met the criteria of a mean Likert score of <2.0 or >4.0. These factors were as follows: age, block to the range of motion (ROM) after aspiration/injection, crepitation with ROM, tenderness over the distal radioulnar joint and/or interosseous membrane (dorsal forearm), gap and/or displacement >2 mm on imaging, complete loss of contact of the head with the rest of the radius on imaging, and fracture head involvement 30% on imaging. Twenty-two (46%) of the 96 clinical scenarios gained >90% consensus in favor of surgical treatment, whereas 8 (17%) reached >90% consensus in favor of nonoperative treatment. CONCLUSION: Obtaining expert consensus on the treatment of radial head fractures remains challenging. Certain factors such as gap/displacement ≥2 mm without complete loss of contact, ≥30% head involvement with a block to an ROM regardless of tenderness over distal radioulnar joint or interosseous membrane (dorsal forearm), or crepitation when the patient was <80 years of age led to a recommendation of operative treatment in 100% of the surveyed surgeons. Patients older than 80 years with no block to ROM after aspiration/injection, no crepitation with ROM, and no tenderness on distal radioulnar joint/interosseous membrane (dorsal forearm) were recommended for nonoperative treatment regardless of the size of the radial head involvement on imaging.

The FDA and Ensuring Safety and Effectiveness of Devices, Biologics, and Technology.

Orthopaedic devices account for nearly 20% of all devices on the market, with more than 600 novel orthopaedic devices cleared or approved by the FDA for marketing in the United States annually. Advances in technology and biologic therapies offer tremendous potential for patients with musculoskeletal ailments; however, it is important that the safety and effectiveness of these products be assessed to safeguard the public health. The FDA uses multiple different premarket pathways for devices, biologics, and combination products based on perceived risk of the novel product. More than 97% of orthopaedic devices go through the FDA's 510(k) pathway, which does not require clinical trials. The remaining high-risk devices must receive premarket approval and submit clinical trial data demonstrating safety and effectiveness. Similarly, high-risk biologics must obtain a biologics license application by submitting clinical trial data. Postmarketing surveillance strategies, including extended clinical trials or real-world evidence from registries, are increasingly being relied on by the FDA to expedite approval while also improving its capacity to identify problematic products.

Risk of Recall Among Medical Devices Undergoing US Food and Drug Administration 510(k) Clearance and Premarket Approval, 2008-2017.

Importance: The US Food and Drug Administration (FDA) uses 510(k) clearance and premarket approval (PMA) pathways to ensure device safety before marketing. Premarket approval evaluates high-risk medical devices and requires clinical trials, whereas 510(k) clearance evaluates moderate-risk devices and relies on benchtop (nonclinical and biomechanical) and descriptive data. Existing literature suggests that the clinical trials required by PMA are associated with reduced risk of recall compared with devices granted 510(k) clearance. Several investigators have found weaknesses in pivotal PMA trials, raising safety concerns. Furthermore, methodological factors may have led to a previous underestimation of recall risk for devices with PMA. Objectives: To compare risk of recall and high-risk recall between devices that received 510(k) clearance and those that received PMA and to compare the risk of recall between devices for medical specialties. Design, Setting, and Participants: This cohort study compared devices with 510(k) clearance vs those with PMA that reached the market between January 1, 2008, and December 31, 2017. Two- to 12-year follow-up was obtained from the FDA's 510(k) and PMA medical device database. Orthopedic surgery was chosen arbitrarily as the reference category for analysis between specialties because no baseline exists. Statistical analysis was performed from February 1 to November 1, 2020. Main Outcomes and Measures: The FDA issues recalls for safety concerns. These recalls are stratified into class I, II, and III, with class I representing high-risk issues for serious harm or death. The main outcome was the hazard ratio of any recall and class I recall between devices with PMA and those with 510(k) clearance. The secondary outcome was the recall hazard ratio between specialties with respect to the reference category. A single Cox proportional hazards regression model evaluating the association of medical specialty and FDA approval pathway with the risk of recall was performed. Results: During the study period, 28 246 devices received 510(k) clearance and 310 devices (10.7%) received PMA; 3012 devices (10.7%) with 510(k) clearance and 84 devices (27.1%) with PMA were recalled. A total of 216 devices (0.8%) with 510(k) clearance and 16 devices (5.2%) with PMA had class I recalls. Devices with PMA compared with those with 510(k) clearance had a hazard ratio for recall of 2.74 (95% CI, 2.19-3.44; P < .001) and a hazard ratio for high-risk recall of 7.30 (95% CI, 4.39-12.13; P < .001). Only radiologic devices were associated with an increased risk of recall (hazard ratio, 1.57; 95% CI, 1.32-1.87; P < .001), whereas 6 specialties were assocated with a decreased risk compared with the orthopedic reference category: general and plastic surgery, otolaryngology, obstetrics and gynecology, physical medicine, hematology, and general hospital. Conclusions and Relevance: This study suggests that high-risk medical devices approved via PMA are associated with a greater risk of recall than previously reported. Most recalls are for devices with 510(k) clearance, also raising safety concerns. Strengthening postmarketing surveillance strategies and pivotal trials may improve device safety.

Vancomycin prophylaxis for revision hip arthroplasty in penicillin and cephalosporin sensitive patients: Is dose adjustment necessary in accordance with blood loss and fluid replacement?

OBJECTIVE: The aims of this study were (1) to investigate the changes in the serum concentration of prophylactically administrated vancomycin in the perioperative period of revision hip arthroplasty in penicillin/cephalosporin-allergic patients, (2) to assess whether the postoperative re-administration of vancomycin is needed, and (3) to determine the relationships of vancomycin serum concentration with blood loss, body weight, and fluid replacement in such patients. METHODS: This study consisted of 29 patients (20 females, 9 males; mean age=63.3 years; age range=45-79 years) with a history of penicillin/cephalosporin allergy undergoing revision hip arthroplasty secondary to aseptic loosening or periprosthetic fractures. Serum vancomycin levels were measured (1) before administration of vancomycin, (2) at the time of skin incision, (3) every 1,5 hours thereafter until the end of the operation, (4) during the skin closure, and (5) after three and 12 hours from the initial dosage. Data regarding body weight, amounts of intraoperative blood loss, fluid and blood replacements and postoperative wound drainage were recorded. RESULTS: The average blood loss, fluid replacement, and drain volume were 1280.3±575.8 (500-2700) mL, 2922.6±768.8 (1700-4600) mL, and 480.2±163.7 (200-850) mL, respectively. The mean levels of serum vancomycin were 46.3±21.8 (14.1-80.7) mg/L at the time of skin incision, 17.9±4.7 (9.4-30.9) and 9.8±2.2 (4.3-13.8) mg/L after 1.5 and 3 hours from the beginning of the surgery and 5.1±1.1 (2.9-6.8)mg/L after 12th hour postoperatively. The measured vancomycin levels were below the effective serum concentrations (< 5 mg/L) for 18 patients at 12 hours the administration of the first dose. A moderate level negative correlation between the blood loss/body weight ratio and vancomycin levels was found (p=0.004, r=-0.493). Predictive ROC curve analysis resulted in determining a blood loss volume higher than 1150 ml and a blood loss/body weight ratio higher than 18,5 is significant to estimate the vancomycin level below the minimum effective serum level at 12th hour postoperatively (AUC=0.793±0.16, p=0.009, AUC=0.753) 26±0.12, p=0.025, respectively). CONCLUSION: Evidence from this study has indicated vancomycin concentration at 12th hour is below the effective level in most patients. Thus, earlier repetitive infusion of vancomycin seems to be necessary in penicillin/cephalosporin-allergic patients undergoing revision hip arthroplasty, especially in those with high blood loss. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Posteromedial rotatory incongruity of the elbow: a computational kinematics study.

BACKGROUND: Our objective was to analyze the effect of different anteromedial coronoid fracture patterns with different combinations of ligamentous repairs. We hypothesized that smaller fractures would be sufficiently treated with ligamentous repair alone but that larger fragments would require a combination of ligament and bony repair versus reconstruction. METHODS: Two multibody models were created from cadaveric specimens in the ADAMS program. Four different conditions were simulated: (1) no fracture, (2) O'Driscoll anteromedial subtype I (2.5-mm) fracture, (3) subtype II 2.5-mm fracture, and (4) subtype II 5-mm fracture. In each of these conditions, 3 ligament repairs were studied: lateral ulnar collateral ligament (LUCL), posterior bundle of the medial collateral ligament (pMCL), and both LUCL and pMCL. For each condition, kinematics and articular contact areas were calculated. RESULTS: LUCL repair alone increases whereas pMCL repair decreases internal rotation of the ulna relative to all tested posteromedial rotatory instability conditions; their rotational effects are summative when both ligaments are repaired. With a subtype I fracture and both pMCL and LUCL injuries, repairing the LUCL alone corrects angulation whereas rotational stability is satisfactory through the arc from 0° to 90°. In a subtype II 2.5-mm fracture, isolated repair of the LUCL or pMCL is not capable of restoring rotation or angulation. For a subtype II 5-mm fracture, no combination of ligamentous repairs could restore rotation or angulation. CONCLUSIONS: This study suggests that LUCL repair alone is sufficient to restore kinematics for small subtype I fractures for an arc avoiding deep flexion; whereas nearly normal kinematics throughout the arc of motion can be achieved if the pMCL is also repaired. Larger anteromedial coronoid fractures should ideally have fragments fixed in addition to ligament repairs.

Medial Collateral Ligament Deficiency of the Elbow Joint: A Computational Approach.

Computational elbow joint models, capable of simulating medial collateral ligament deficiency, can be extremely valuable tools for surgical planning and refinement of therapeutic strategies. The objective of this study was to investigate the effects of varying levels of medial collateral ligament deficiency on elbow joint stability using subject-specific computational models. Two elbow joint models were placed at the pronated forearm position and passively flexed by applying a vertical downward motion on humeral head. The models included three-dimensional bone geometries, multiple ligament bundles wrapped around the joint, and the discretized cartilage representation. Four different ligament conditions were simulated: All intact ligaments, isolated medial collateral ligament (MCL) anterior bundle deficiency, isolated MCL posterior bundle deficiency, and complete MCL deficiency. Minimal kinematic differences were observed for isolated anterior and posterior bundle deficient elbows. However, sectioning the entire MCL resulted in significant kinematic differences and induced substantial elbow instability. Joint contact areas were nearly similar for the intact and isolated posterior bundle deficiency. Minor differences were observed for the isolated anterior bundle deficiency, and major differences were observed for the entire MCL deficiency. Complete elbow dislocations were not observed for any ligament deficiency level. As expected, during isolated anterior bundle deficiency, the remaining posterior bundle experiences higher load and vice versa. Overall, the results indicate that either MCL anterior or posterior bundle can provide anterior elbow stability, but the anterior bundle has a somewhat bigger influence on joint kinematics and contact characteristics than posterior one. A study with a larger sample size could help to strengthen the conclusion and statistical significant.

Long-term outcome of custom triflange outrigger ulnar component in revision total elbow arthroplasty.

BACKGROUND: Patients missing the distal humeral condyles are prone to premature bushing wear after total elbow arthroplasty. A midterm study has demonstrated that a custom triflange outrigger ulnar component was successful in preventing this. The aim of this study was to determine whether these results remained stable over time. MATERIALS AND METHODS: The outcomes of 6 patients who underwent revision of a loose ulnar component using a custom triflange outrigger component were reviewed in this retrospective case study. The average patient age at the time of revision was 51. The average number of prior operations was 2 (range, 1-3). The mean follow-up was 15 years (range, 10-18 years). RESULTS: At final follow-up, the mean range of extension-flexion was 35° to 135°, and pronation-supination was 65° to 63°. The average Mayo Elbow Performance Score improved to 75 of 100. Four implants were still in place with no radiolucencies or osteolysis. Three patients required revision surgery for broken humeral stems. Two required conversion to another total elbow arthroplasty system after 18 and 14 years for humeral component loosening. CONCLUSIONS: These components lasted an average of 4 times longer than the original ulnar components. In our experience, periarticular osteolysis caused by polyethylene wear creates a region of unsupported stem and a stress riser at the junction with the remaining well-supported stem and causes component stem fractures. The concept of an outrigger type of hinge might be useful for active patients requiring an elbow prosthesis in the setting of deficient condyles.

Musculoskeletal Model Development of the Elbow Joint with an Experimental Evaluation.

A dynamic musculoskeletal model of the elbow joint in which muscle, ligament, and articular surface contact forces are predicted concurrently would be an ideal tool for patient-specific preoperative planning, computer-aided surgery, and rehabilitation. Existing musculoskeletal elbow joint models have limited clinical applicability because of idealizing the elbow as a mechanical hinge joint or ignoring important soft tissue (e.g., cartilage) contributions. The purpose of this study was to develop a subject-specific anatomically correct musculoskeletal elbow joint model and evaluate it based on experimental kinematics and muscle electromyography measurements. The model included three-dimensional bone geometries, a joint constrained by multiple ligament bundles, deformable contacts, and the natural oblique wrapping of ligaments. The musculoskeletal model predicted the bone kinematics reasonably accurately in three different velocity conditions. The model predicted timing and number of muscle excitations, and the normalized muscle forces were also in agreement with the experiment. The model was able to predict important in vivo parameters that are not possible to measure experimentally, such as muscle and ligament forces, and cartilage contact pressure. In addition, the developed musculoskeletal model was computationally efficient for body-level dynamic simulation. The maximum computation time was less than 30 min for our 35 s simulation. As a predictive clinical tool, the potential medical applications for this model and modeling approach are significant.

The annular ligament-revisited.

BACKGROUND: Studies investigating the annular ligament have presented confusing information about its anatomy and nomenclature. Cadaver elbow dissections were used to clarify the anatomy and terminology of the annular ligament. METHODS: Nineteen elbows were dissected (7 fresh frozen and 12 embalmed). Target structures were identified, photographed, and measured by independent observers. RESULTS: There are 3 layers to the lateral elbow ligaments: the superficial lateral ulnar collateral and radial collateral ligament; a deeper layer of the superior oblique band (SOB) and inferior oblique band (IOB) of the annular ligament; and the deepest capsular layer. The annular ligament measured 9.5 ± 1.4 mm anteriorly. The SOB (15/19) was 3.9 ± 1.0 mm wide by 10.5 ± 3.8 mm long. The IOB (13/19) was 3.6 ± 1.1 mm wide by 11.4 ± 4.2 mm long. The IOB inserts onto the anterior proximal ulna rather than the supinator crest. The anterior oblique band (8/19) was 3.8 ± 1.7 mm wide. CONCLUSION: The SOB and IOB were present in the majority of specimens. The previously described accessory lateral collateral ligament is a localized thickening on the lateral ligament complex arising from the supinator insertion independent of the IOB that attaches to the annular ligament inferiorly and distally and attaches onto the proximal anterior ulna at the bicipital fossa floor, medial to the supinator crest.

Ulna-humerus contact mechanics: Finite element analysis and experimental measurements using a tactile pressure sensor.

Elbow articular cartilage withstands high compressive and shear forces while protecting the bone from excessive loading. Better understanding of elbow cartilage contact mechanics can provide insight into cartilage degeneration. In this study a tactile pressure sensor was used to measure the contact pressure distribution within the ulno-humeral joint of two cadaver specimens at 20° flexion angle across three different axial loads of 80 N, 110 N, and 140 N. Corresponding 3D finite element (FE) models were constructed from magnetic resonance imaging (MRI) and contact analysis was performed for each specimen with boundary and loading conditions identical to the experiment. Direct comparison between FE results and experimental measurements was conducted for the validation of the FE models and a sensitivity analysis was employed for assessing the effect of cartilage parameters on the model's outputs. The results showed a good agreement between the FE models and the experiments in terms of contact characteristics. The sensitivity analysis demonstrated that outcomes of the model, particularly peak contact pressure is more sensitive to the Poisson's ratio rather than to Young's modulus under static conditions. This result suggests that selection of Poisson's ratio is very critical for accurate prediction of contact mechanics within the ulno-humeral joint.

Current concepts in elbow arthroplasty.

Distal humeral replacement and the total elbow are two commonly-used arthroplastiesEach prosthesis has evolving indications and surgical techniquesRecent changes in device design and implantation methods are due to biomechanical and clinical outcome-based researchNew prostheses and methods provide: better elbow kinematics, more durable bearings and longer-lasting joint replacement potential Cite this article: EFORT Open Rev 2017;2:83-88. DOI: 10.1302/2058-5241.2.160064.

Distal Humeral Hemiarthroplasty Versus Total Elbow Arthroplasty for Acute Distal Humeral Fractures.

For acute distal humeral fractures not amenable to open reduction and internal fixation, total elbow arthroplasty has become an established alternative. However, lifelong activity restrictions designed to prevent early mechanical failure make this a poor option for some patients. This has led to a renewed interest in distal humeral hemiarthroplasty. Using modern implants and techniques, distal humeral hemiarthroplasty has shown outcomes comparable to those of total elbow arthroplasty at short- to mid-term follow-up, with an overall higher but different complication rate. Long-term data are needed, but the available literature suggests that distal humeral hemiarthroplasty be considered as another option on the treatment spectrum in select patient populations. [Orthopedics. 2017; 40(1):13-23.].

Adverse Effects of Smoking on Musculoskeletal Health.

Smoking remains a prevalent part of present day society, with over 42 million Americans who continue to use cigarettes. Smoking is strongly associated with a variety of conditions that result in increased morbidity and mortality. Research also indicates that smoking has an adverse effect on surgical outcomes. Its effect on the musculoskeletal system is evident and results in postoperative complications such as infection, nonunion, and malunion. These complications also come with a price, as there are severe economic implications of smoking. Patients who smoke may benefit from a period of perioperative cessation to help diminish some of these negative outcomes. It is the physician's duty to educate patients preoperatively about these outcomes and the potential benefit of smoking cessation.

The Economic Impact of Orthopaedics in Missouri.

Orthopaedics contributes a significant benefit to the Missouri economy. Economic modeling and data quantified the direct and indirect impact within Missouri. Multipliers were applied to direct expenditures to calculate the indirect impact attributable to initial spending. Nearly $1.8 billion can be attributed to the output of orthopaedic related services. The related physical therapy industry increases this figure to nearly $2.3 billion. It is clear that orthopaedics benefits Missouri with both medical services and economic growth.

Prediction of elbow joint contact mechanics in the multibody framework.

Computational multibody musculoskeletal models of the elbow joint that are capable of simultaneous and accurate predictions of muscle and ligament forces, along with cartilage contact mechanics can be immensely useful in clinical practice. As a step towards producing a musculoskeletal model that includes the interaction between cartilage and muscle loading, the goal of this study was to develop subject-specific multibody models of the elbow joint with discretized humerus cartilage representation interacting with the radius and ulna cartilages through deformable contacts. The contact parameters for the compliant contact law were derived using simplified elastic foundation contact theory. The models were then validated by placing the model in a virtual mechanical tester for flexion-extension motion similar to a cadaver experiment, and the resulting kinematics were compared. Two cadaveric upper limbs were used in this study. The humeral heads were subjected to axial motion in a mechanical tester and the resulting kinematics from three bones were recorded for model validation. The maximum RMS error between the predicted and measured kinematics during the complete testing cycle was 2.7 mm medial-lateral translation and 9.7° varus-valgus rotation of radius relative to humerus (for elbow 2). After model validation, a lateral ulnar collateral ligament (LUCL) deficient condition was simulated and, contact pressures and kinematics were compared to the intact elbow model. A noticeable difference in kinematics, contact area, and contact pressure were observed for LUCL deficient condition. LUCL deficiency induced higher internal rotations for both the radius and ulna during flexion and an associated medial shift of the articular contact area.