Surgeon Upper Extremity Kinematics During Error and Error-Free Retropubic Trocar Passage.

Introduction And Hypothesis: Surgeon kinematics play a significant role in the prevention of patient injury. We hypothesized that elbow extension and ulnar wrist deviation are associated with bladder injury during simulated midurethral sling (MUS) procedures.

Methods: We used motion capture technology to measure surgeons' flexion/extension, abduction/adduction, and internal/external rotation angular time series for shoulder, elbow, and wrist joints.

Cognitive models for mentally visualizing a sharp instrument in a blind procedure.

Purpose: Our objective was to understand the cognitive strategies used by surgeons to mentally visualize navigation of a surgical instrument through blind space.

Methods: We conducted semi-structured interviews with 15 expert and novice surgeons following simulated retropubic trocar passage on 3D-printed models of pelvises segmented from preop MRIs. Midurethral sling surgery involves blind passage of a trocar among the urethra, bladder, iliac vessels, and bowel while relying primarily on haptic feedback from the suprapubic bone (SPB) for guidance.

Surgeon estimation of retropubic trocar position in blind 3D space.

Introduction And Hypothesis: Retropubic midurethral sling surgery involves the blind passage of trocars near vital organs. We quantified the proximity of surgeons' mental representation of trocar position relative to actual position using a pelvis simulation platform. We hypothesized that novice surgeons, compared with experts, would estimate the trocar's location to be further from the actual location.

Retropubic trocar modified with a load cell to verify contact with pubic bone.

Background: Vital injuries during midurethral sling surgery are avoided by maintaining constant trocar contact with bone, and yet this is challenging for a teaching surgeon to monitor during this blind procedure. We modified a retropubic trocar with a load cell to distinguish on-bone and off-bone movement and tested it on a midurethral sling surgery 3-dimensional surgery simulator.

Methods: Two experts and 3 novice surgeons performed retropubic trocar passage on the physical pelvic floor model using the modified trocar.

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.

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.

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.

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.

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.

Lateral collateral ligament deficiency of the elbow joint: A modeling approach.

A computational model capable of predicting the effects of lateral collateral ligament deficiency of the elbow joint would be a valuable tool for surgical planning and prediction of the long-term consequences of ligament deficiency. The purpose of this study was to simulate lateral collateral ligament deficiency during passive flexion using a computational multibody elbow joint model and investigate the effects of ligament insufficiency on the kinematics, ligament loads, and articular contact characteristics (area, pressure). The elbow was placed initially at approximately 20° of flexion and a 345 mm vertical downward motion profile was applied over 40 s to the humerus head.

Evaluation of a musculoskeletal model with prosthetic knee through six experimental gait trials.

Knowledge of the forces acting on musculoskeletal joint tissues during movement benefits tissue engineering, artificial joint replacement, and our understanding of ligament and cartilage injury. Computational models can be used to predict these internal forces, but musculoskeletal models that simultaneously calculate muscle force and the resulting loading on joint structures are rare. This study used publicly available gait, skeletal geometry, and instrumented prosthetic knee loading data [1] to evaluate muscle driven forward dynamics simulations of walking.

Concurrent prediction of muscle and tibiofemoral contact forces during treadmill gait.

Detailed knowledge of knee kinematics and dynamic loading is essential for improving the design and outcomes of surgical procedures, tissue engineering applications, prosthetics design, and rehabilitation. This study used publicly available data provided by the "Grand Challenge Competition to Predict in-vivo Knee Loads" for the 2013 American Society of Mechanical Engineers Summer Bioengineering Conference (Fregly et al., 2012, "Grand Challenge Competition to Predict in vivo Knee Loads," J.

Multibody muscle driven model of an instrumented prosthetic knee during squat and toe rise motions.

Detailed knowledge of knee joint kinematics and dynamic loading is essential for improving the design and outcomes of surgical procedures, tissue engineering applications, prosthetics design, and rehabilitation. The need for dynamic computational models that link kinematics, muscle and ligament forces, and joint contacts has long been recognized but such body-level forward dynamic models do not exist in recent literature. A main barrier in using computational models in the clinic is the validation of the in vivo contact, muscle, and ligament loads.

Development and validation of a multi-body model of the canine stifle joint.

Multi-body musculoskeletal models that can be used concurrently to predict joint contact pressures and muscle forces would be extremely valuable in studying the mechanics of joint injury. The purpose of this study was to develop an anatomically correct canine stifle joint model and validate it against experimental data. A cadaver pelvic limb from one adult dog was used in this study.

Effects of age and localized muscle fatigue on ankle plantar flexor torque development.

Background And Purpose: Older adults often experience age-related declines in strength, which contribute to fall risk. Such age-related levels of fall risk may be compounded by further declines in strength caused by acute muscle fatigue. Both age- and fatigue-related strength reductions likely impact the ability to quickly develop joint torques needed to arrest falls.

Postural sway in patients with mild to moderate Parkinson's disease.

Clinical assessment of postural instability in persons with Parkinson's disease (PD) is done with the retropulsive pull test, but since this test does not assess the underlying causes of postural instability, there is a need for additional assessment tools. The aim of this study was to identify postural sway parameters for use in a multifactorial approach to quantify postural instability. Nineteen adults diagnosed with idiopathic PD, 14 healthy age-matched controls (EH), and 10 healthy young adults (YH) completed the study.

Early biomechanical markers of postural instability in Parkinson's disease.

Current clinical assessments do not adequately detect the onset of postural instability in the early stages of Parkinson's disease (PD). The aim of this study was to identify biomechanical variables that are sensitive to the effects of early Parkinson's disease on the ability to recovery from a balance disturbance. Ten adults diagnosed with idiopathic PD and no clinically detectable postural instability, and ten healthy age-range matched controls (HC) completed the study.

Between-day reliability of upper extremity H-reflexes.

H-reflexes are useful for evaluating the group Ia monosynaptic reflex excitability in the lower and upper extremities (UEs). However, there is no established between-day protocol for measuring H-reflex excitability in the UE extensor carpi radialis longus (ECRL). The purpose of this study was to develop a reliable protocol to measure the H-reflex excitability between-days for the ECRL, and the antagonist muscle, the flexor carpi radialis (FCR).

Effects of step length on stepping responses used to arrest a forward fall.

This study investigated effects of step length on the stepping response used to arrest an impending forward fall. Twelve healthy young (mean age 22, S.D.

The use of correlation integrals in the study of localized muscle fatigue of elbow flexors during maximal efforts.

Innovative applications of non-linear time series analysis have recently been used to investigate physiological phenomena. In this study, we investigated the feasibility of using the correlation integral to monitor the localized muscle fatigue process in the biceps brachii during sustained maximal efforts. The subjects performed isometric maximum contractions until failure in elbow flexion (90 degrees from neutral).

Ipsilateral deficits of targeted movements after stroke.

Objective: To test the hypotheses that targeted movements of both the ipsilateral and the contralateral extremities of stroke survivors would be prolonged compared with those from a control group without stroke, and that the ipsilateral deficit would occur in movements toward small, but not large, targets.

Design: Descriptive study.

Setting: Motor performance laboratory.