Optimizing Web-Based Viewer of 4D CT Scans for Clinical Assessment of Injured Wrists.

Wrist injuries pose a unique challenge for patients and providers. Due to the complexity of the wrist, it is difficult to determine if a wrist injury is primarily a bone fracture or soft tissue damage. The scapholunate interosseous ligament (SLIL) is an important ligament in the function of the wrist, and it is also one of the most common soft tissue injuries in the wrist. Wrist arthroscopy is the gold standard for assessing injuries of the scapholunate joint; however, it is an invasive procedure. Recent advances in dynamic imaging with 4D Computed Tomography scans allow for the assessment of SLIL injuries non-invasively. Unfortunately, 4DCT scan data can be difficult to disseminate to clinical practitioners due to the large amount of data generated and the complexity in visualizing the data. A web-based application has been developed to interactively assess 4DCT scans of patients with suspected SLIL injury. Due to the magnitude of data and the diversity of hardware platforms used to visualize the data, the images are preprocessed with a rendering engine and presented in a pseudo-3D visualization paradigm where the user can interactively explore the 3D data without transmitting the entire dataset to the local computer. The technology has been used to assess 27 patients.

Quantitative Assessment of Clinician Assistance During Dynamic Rehabilitation Using Force Sensitive Resistors.

Background: Neuromodulation using epidural electrical stimulation (EES) has shown functional restoration in humans with chronic spinal cord injury (SCI). EES during body weight supported treadmill training (BWSTT) enhanced stepping performance in clinical trial participants with paraplegia. Unfortunately, tools are lacking in availability to quantify clinician assistance during BWSTT with and without EES. Force sensitive resistors (FSRs) have previously quantified clinician assistance during static standing; however, dynamic tasks have not been addressed. Objective: To determine the validity of FSRs in measurements of force and duration to quantify clinician assistance and participant progression during BWSTT with EES in participants with SCI. Design: A feasibility study to determine the effectiveness of EES to restore function in individuals with SCI. Methods: Two male participants with chronic SCI were enrolled in a pilot phase clinical trial. Following implantation of an EES system in the lumbosacral spinal cord, both participants underwent 12 months of BWSTT with EES. At monthly intervals, FSRs were positioned on participants' knees to quantity forces applied by clinicians to achieve appropriate mechanics of stepping during BWSTT. The FSRs were validated on the benchtop using a leg model instrumented with a multiaxial load cell as the gold standard. The outcomes included clinician-applied force duration measured by FSR sensors and changes in applied forces indicating progression over the course of rehabilitation. Results: The force sensitive resistors validation revealed a proportional bias in their output. Loading required for maximal assist training exceeded the active range of the FSRs but were capable of capturing changes in clinician assist levels. The FSRs were also temporally responsive which increased utility for accurately assessing training contact time. The FSRs readings were able to capture independent stance for both participants by study end. There was minimal to no applied force bilaterally for participant 1 and unilaterally for participant 2. Conclusions: Clinician assistance applied at the knees as measured through FSRs during dynamic rehabilitation and EES (both on and off) effectively detected point of contact and duration of forces; however, it lacks accuracy of magnitude assessment. The reduced contact time measured through FSRs related to increased stance duration, which objectively identified independence in stepping during EES-enabled BWSTT following SCI.

A Simulation Suture Compared With a Clinical Suture for Training on Laparoscopic Simulators: Objective Measurements Indicate Acceptable Physical Characteristics.

OBJECTIVE: Simulation sutures are a low-cost option for training purposes, but they may not perform as well as the more expensive clinical suture. Trainees at our institution have raised concerns about their quality and integrity compared with clinical suture. The objective was to determine whether significant differences in strength of the sutures and knot holding capabilities between low and high-cost sutures existed. METHODS: Two sutures were compared: 3-0 braided silk simulation suture (Sim*Vivo LLC, Willsboro, NY) and 3-0 Perma-Hand silk braided clinical suture (Ethicon, Somerville, NJ). The diameter of the suture was assessed with light microscopy. Tensile strength of the suture and knotted suture were assessed. Both sutures were tested dry and wet. RESULTS: Tensile strength of the sutures, knotted or unknotted, were not significantly different. Knot type did not change this comparison. Soaking in saline did not change the tensile strength but did introduce a substantial difference in knot failure mode between sutures. The mean diameter of the Ethicon suture was larger than that of the Sim*Vivo suture, which could influence suture behavior. CONCLUSIONS: The applied mechanical tests identified that clinical and simulation sutures differ some in their inherent mechanical characteristics related to suture handling. However, these differences did not translate to a key measure of performance of a sutured junction, namely, the strength of the knotted suture. Based on the results of the study, any subjective impressions of simulation suture strength and knot holding should not negatively impact its use for medical education.

Rotator cuff repair with a novel mesh suture: An ex vivo assessment of mechanical properties.

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy-two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques-simple interrupted sutures and two-row suture bridge-were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull-out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re-tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987-992, 2018.

Transverse ultrasound assessment of median nerve deformation and displacement in the human carpal tunnel during wrist movements.

The symptoms of carpal tunnel syndrome, a compression neuropathy of the median nerve at the wrist, are aggravated by wrist motion, but the effect of these motions on median nerve motion are unknown. To better understand the biomechanics of the abnormal nerve, it is first necessary to understand normal nerve movement. The purpose of this study was to evaluate the deformation and displacement of the normal median nerve at the proximal carpal tunnel level on transverse ultrasound images during different wrist movements, to have a baseline for comparison with abnormal movements. Dynamic ultrasound images of both wrists of 10 asymptomatic volunteers were obtained during wrist maximal flexion, extension and ulnar deviation. To simplify the analysis, the initial and final shape and position of the median nerve were measured and analyzed. The circularity of the median nerve was significantly increased and the aspect ratio and perimeter were significantly decreased in the final image compared with the first image during wrist flexion with finger extension, wrist flexion with finger flexion and wrist ulnar deviation with finger extension (p < 0.01). There were significant differences in median nerve displacement vector between finger flexion, wrist flexion with finger extension and wrist ulnar deviation with finger extension (all p's < 0.001). The mean amplitudes of median nerve motion in wrist flexion with finger extension (2.36 ± 0.79 normalized units [NU]), wrist flexion with finger flexion (2.46 ± 0.84 NU) and wrist ulnar deviation with finger extension (2.86 ± 0.51 NU) were higher than those in finger flexion (0.82 ± 0.33 NU), wrist extension with finger extension (0.77 ± 0.46 NU) and wrist extension with finger flexion (0.81 ± 0.58 NU) (p < 0.0001). In the normal carpal tunnel, wrist flexion and ulnar deviation could induce significant transverse displacement and deformation of the median nerve.