Detection of scapholunate interosseous ligament injury using dynamic computed tomography-derived arthrokinematics: A prospective clinical trial.

Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

Relationship Between the Changes of Tendon Elastic Moduli With Ultrasound Shear Wave Elastography and Mechanical Compression Test.

OBJECTIVE: The purpose of this study was to investigate the consistency of the changes in the elastic modulus measured with ultrasound shear wave elastography (SWE) with changes measured through mechanical testing using tendons that were artificially altered by chemical modifications. METHODS: Thirty-six canine flexor digitorum profundus tendons were used for this experiment. To mimic tendon mechanical property changes induced by tendinopathy conditions, tendons were treated with collagenase to soften the tissue by collagen digestion or with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) to stiffen the tissues through chemical crosslinking. Tendons were randomly assigned to one of three groups: immersion in phosphate-buffered saline (PBS) as a control group (n = 12), collagenase treatment (n = 12) or EDC treatment (n = 12). Immediately following SWE measurement of each tendon, mechanical compression testing was performed as a gold standard to validate the SWE measurement. Both tests were conducted before and after treatment. RESULTS: The compressive modulus and SWE shear modulus significantly decreased after collagenase treatment. Conversely, both moduli significantly increased after EDC treatment. There was no significant difference in either modulus before or after PBS treatment. As a result of a regression analysis with the percentage change of the compressive modulus as the dependent variable and SWE shear modulus as the independent variable, the best-fit regression was found to be an exponential function and the coefficient of determination was 0.687. CONCLUSION: The changes in the compressive moduli and SWE shear moduli in tendons induced by chemical treatments were correlated by approximately 70%.

Bilateral lunotriquetral coalition: a dynamic four-dimensional computed tomography technical case report.

Lunotriquetral coalitions are the most common form of carpal coalition wherein the cartilage between the lunate and triquetrum ossification centers failed to undergo apoptosis. This technical case report examines the arthrokinematics of bilateral lunotriquetral coalitions with dissimilar Minnaar types in one participant with one asymptomatic wrist and one wrist with suspected distal radioulnar joint injury. Static and dynamic (four-dimensional) CT images during pronosupination were captured using a photon-counting detector CT scanner. Interosseous proximity distributions were calculated between the lunotriquetral coalition and adjacent bones in both wrists to quantify arthrokinematics. Interosseous proximity distributions at joints adjacent to the lunotriquetral coalition demonstrate differences in median and minimum interosseous proximities between the asymptomatic and injured wrists during resisted pronosupination. Altered kinematics from lunotriquetral coalitions may be a source of ulnar-sided wrist pain and discomfort, limiting the functional range of motion. This case report highlights potential alterations to wrist arthrokinematics in the setting of lunotriquetral coalitions and possible associations with ulnar-sided wrist pain, highlighting anatomy to examine in radiographic follow-up. Furthermore, this case report demonstrates the technical feasibility of four-dimensional CT using photon-counting detector technology in assessing arthrokinematics in the setting of variant wrist anatomy.

Improving Mechanical Properties of Tendon Allograft through Rehydration Strategies: An In Vitro Study.

Allogenic tendons grafts sourced from intrasynovial tendons are often used for tendon reconstruction. Processing is achieved through repetitive freeze-thaw cycles followed by lyophilization. Soaking the lyophilized tendon in saline (0.9%) for 24 h is the standard practice for rehydration. However, data supporting saline rehydration over the use of other hydrating solutions are scant. The purpose of the current study was to compare the effects of different rehydration solutions on biomechanical properties of lyophilized tendon allograft. A total of 36 canine flexor digitorum profundus tendons were collected, five freeze-thaw cycles followed by lyophilization were performed for processing, and then divided into three groups rehydrated with either saline solution (0.9%), phosphate-buffered saline (PBS), or minimum essential medium (MEM). Flexural stiffness, tensile stiffness, and gliding friction were evaluated before and after allograft processing. The flexural moduli in both fibrous and fibrocartilaginous regions of the tendons were measured. After lyophilization and reconstitution, the flexural moduli of both the fibrocartilaginous and non-fibrocartilaginous regions of the tendons increase significantly in the saline and MEM groups (p < 0.05). Compared to the saline and MEM groups, the flexural moduli of the fibrocartilaginous and non-fibrocartilaginous regions of tendons rehydrated with PBS are significantly lower (p < 0.05). Tensile moduli of rehydrated tendons are significantly lower than those of fresh tendons for all groups (p < 0.05). The gliding friction of rehydrated tendons is significantly higher than that of fresh tendons in all groups (p < 0.05). There is no significant difference in either tensile moduli or gliding friction between tendons treated with different rehydration solutions. These results demonstrate that allograft reconstitution can be optimized through careful selection of hydrating solution and that PBS could be a better choice as the impact on flexural properties is lower.

Evaluation of Scapholunate Injury and Repair with Dynamic (4D) CT: A Preliminary Report of Two Cases.

Background In predynamic or dynamic scapholunate (SL) instability, standard diagnostic imaging may not identify SL interosseous ligament (SLIL) injury, leading to delayed detection and intervention. This study describes the use of four-dimensional computed tomography (4DCT) in identifying early SLIL injury and following injured wrists to 1-year postoperatively. Description of Technique 4DCT acquires a series of three-dimensional volume data with high temporal resolution (66 ms). 4DCT-derived arthrokinematic data can be used as biomarkers of ligament integrity. Patients and Methods This study presents the use of 4DCT in a two-participant case series to assess changes in arthrokinematics following unilateral SLIL injury preoperatively and 1-year postoperatively. Patients were treated with volar ligament repair with volar capsulodesis and arthroscopic dorsal capsulodesis. Arthrokinematics were compared between uninjured, preoperative injured, and postoperative injured (repaired) wrists. Results 4DCT detected changes in interosseous distances during flexion-extension and radioulnar deviation. Generally, radioscaphoid joint distances were greatest in the uninjured wrist during flexion-extension and radioulnar deviation, and SL interval distances were smallest in the uninjured wrist during flexion-extension and radioulnar deviation. Conclusion 4DCT provides insight into carpal arthrokinematics during motion. Distances between the radioscaphoid joint and SL interval can be displayed as proximity maps or as simplified descriptive statistics to facilitate comparisons between wrists and time points. These data offer insight into areas of concern for decreased interosseous distance and increased intercarpal diastasis. This method may allow surgeons to assess whether (1) injury can be visualized during motion, (2) surgery repaired the injury, and (3) surgery restored normal carpal motion. Level of Evidence Level IV, Case series.

The Effect of Pulling Angle on Rotator Cuff Mechanical Properties in a Canine In Vitro Model.

The objective of this study was to examine the effect of pulling angle on time-zero mechanical properties of intact infraspinatus tendon or infraspinatus tendon repaired with the modified Mason-Allen technique in a canine model in vitro. Thirty-six canine shoulder samples were used. Twenty intact samples were randomly allocated into functional pull (135°) and anatomic pull (70°) groups (n = 10 per group). The remaining sixteen infraspinatus tendons were transected from the insertion and repaired using the modified Mason-Allen technique before being randomly allocated into functional pull or anatomic pull groups (n = 8 per group). Load to failure testing was performed on all specimens. The ultimate failure load and ultimate stress of the functional pulled intact tendons were significantly lower compared with anatomic pulled tendons (1310.2 ± 167.6 N vs. 1687.4 ± 228.2 N, p = 0.0005: 55.6 ± 8.4 MPa vs. 67.1 ± 13.3 MPa, p = 0.0334). For the tendons repaired with the modified Mason-Allen technique, no significant differences were observed in ultimate failure load, ultimate stress or stiffness between functional pull and anatomic pull groups. The variance of pulling angle had a significant influence on the biomechanical properties of the rotator cuff tendon in a canine shoulder model in vitro. Load to failure of the intact infraspinatus tendon was lower at the functional pulling position compared to the anatomic pulling position. This result indicates that uneven load distribution across tendon fibers under functional pull may predispose the tendon to tear. However, this mechanical character is not presented after rotator cuff repair using the modified Mason-Allen technique.

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.

Voluntary Modulation of Evoked Responses Generated by Epidural and Transcutaneous Spinal Stimulation in Humans with Spinal Cord Injury.

Transcutaneous (TSS) and epidural spinal stimulation (ESS) are electrophysiological techniques that have been used to investigate the interactions between exogenous electrical stimuli and spinal sensorimotor networks that integrate descending motor signals with afferent inputs from the periphery during motor tasks such as standing and stepping. Recently, pilot-phase clinical trials using ESS and TSS have demonstrated restoration of motor functions that were previously lost due to spinal cord injury (SCI). However, the spinal network interactions that occur in response to TSS or ESS pulses with spared descending connections across the site of SCI have yet to be characterized. Therefore, we examined the effects of delivering TSS or ESS pulses to the lumbosacral spinal cord in nine individuals with chronic SCI. During low-frequency stimulation, participants were instructed to relax or attempt maximum voluntary contraction to perform full leg flexion while supine. We observed similar lower-extremity neuromusculature activation during TSS and ESS when performed in the same participants while instructed to relax. Interestingly, when participants were instructed to attempt lower-extremity muscle contractions, both TSS- and ESS-evoked motor responses were significantly inhibited across all muscles. Participants with clinically complete SCI tested with ESS and participants with clinically incomplete SCI tested with TSS demonstrated greater ability to modulate evoked responses than participants with motor complete SCI tested with TSS, although this was not statistically significant due to a low number of subjects in each subgroup. These results suggest that descending commands combined with spinal stimulation may increase activity of inhibitory interneuronal circuitry within spinal sensorimotor networks in individuals with SCI, which may be relevant in the context of regaining functional motor outcomes.

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 novel engineered purified exosome product patch for tendon healing: An explant in an ex vivo model.

Reducing tendon failure after repair remains a challenge due to its poor intrinsic healing ability. The purpose of this study is to investigate the effect of a novel tissue-engineered purified exosome product (PEP) patch on tendon healing in a canine ex vivo model. Lacerated flexor digitorum profundus (FDP) tendons from three canines' paws underwent simulated repair with Tisseel patch alone or biopotentiated with PEP. For the ex vivo model, FDP tendons were randomly divided into three groups: FDP tendon repair alone group (Control), Tisseel patch alone group, and the Tisseel plus PEP (TEPEP) patch group. Following 4 weeks of tissue culture, the failure load, stiffness, histology, and gene expression of the healing tendon were evaluated. Transmission electron microscopy revealed that in exosomes of PEP the diameters ranged from 93.70 to 124.65 nm, and the patch release test showed this TEPEP patch could stably release the extracellular vesicle over 2 weeks. The failure strength of the tendon in the TEPEP patch group was significantly higher than that of the Control group and Tisseel alone group. The results of histology showed that the TEPEP patch group had the smallest healing gap and the largest number of fibroblasts on the surface of the injured tendon. Quantitative reverse transcription polymerase chain reaction showed that TEPEP patch increased the expression of collagen type III, matrix metallopeptidase 2 (MMP2), MMP3, MMP14, and reduced the expression of transforming growth factor ß1, interleukin 6. This study shows that the TEPEP patch could promote tendon repair by reducing gap formation and inflammatory response, increasing the activity of endogenous cells, and formation of type III collagen.

The effect of fibrin formulation on cell migration in an in vitro tendon repair model.

BACKGROUND: The purpose of this study was to determine the effect of fibrinogen concentration on cell viability and migration in a tissue culture tendon healing model. METHODS: Forty-eight canine flexor digitorum profundus tendons were randomly divided into three groups. In each group the tendons were lacerated and repaired augmented with a canine bone marrow stromal cell seeded fibrin interposition patch using either 5 mg/ml fibrinogen and 25 U/ml thrombin (physiological as a control), 40 mg/ml fibrinogen and 250 U/ml thrombin (low adhesive), or 80 mg/ml fibrinogen and 250 U/ml thrombin (high adhesive). The sutured tendons were cultured for two or four weeks. RESULTS: Failure load was not significantly different among the groups. Cell-labeling staining showed that the stromal cells migrated across the gap in the control and low adhesive groups, but there was no cell migration in the high adhesive group at two weeks. CONCLUSION: A high fibrinogen concentration in a fibrin patch or glue may impede early cell migration. LEVEL OF EVIDENCE: Not applicable because this study was a laboratory study.

Biomechanical evaluation of a novel double rip-stop technique with medial row knots for rotator cuff repair: an in vitro study.

AIMS: Many biomechanical studies have shown that the weakest biomechanical point of a rotator cuff repair is the suture-tendon interface at the medial row. We developed a novel double rip-stop (DRS) technique to enhance the strength at the medial row for rotator cuff repair. The objective of this study was to evaluate the biomechanical properties of the DRS technique with the conventional suture-bridge (SB) technique and to evaluate the biomechanical performance of the DRS technique with medial row knots. METHODS: A total of 24 fresh-frozen porcine shoulders were used. The infraspinatus tendons were sharply dissected and randomly repaired by one of three techniques: SB repair (SB group), DRS repair (DRS group), and DRS with medial row knots repair (DRSK group). Specimens were tested to failure. In addition, 3 mm gap formation was measured and ultimate failure load, stiffness, and failure modes were recorded. RESULTS: The mean load to create a 3 mm gap formation in the DRSK and DRS groups was significantly higher than in the SB group. The DRSK group had the highest load to failure with a mean ultimate failure load of 395.0 N (SD 56.8) compared to the SB and DRS groups, which recorded 147.1 N (SD 34.3) and 285.9 N (SD 89.8), respectively (p < 0.001 for both). The DRS group showed a significantly higher mean failure load than the SB group (p = 0.006). Both the DRS and DRSK groups showed significantly higher mean stiffness than the SB group. CONCLUSION: The biomechanical properties of the DRS technique were significantly improved compared to the SB technique. The DRS technique with medial row knots showed superior biomechanical performance than the DRS technique alone.

Accelerated osteocyte senescence and skeletal fragility in mice with type 2 diabetes.

The worldwide prevalence of type 2 diabetes (T2D) is increasing. Despite normal to higher bone density, patients with T2D paradoxically have elevated fracture risk resulting, in part, from poor bone quality. Advanced glycation endproducts (AGEs) and inflammation as a consequence of enhanced receptor for AGE (RAGE) signaling are hypothesized culprits, although the exact mechanisms underlying skeletal dysfunction in T2D are unclear. Lack of inducible models that permit environmental (in obesity) and temporal (after skeletal maturity) control of T2D onset has hampered progress. Here, we show in C57BL/6 mice that a onetime pharmacological intervention (streptozotocin, STZ) initiated in adulthood combined with high-fat diet-induced (HFD-induced) obesity caused hallmark features of human adult-onset T2D, including prolonged hyperglycemia, insulin resistance, and pancreatic ß cell dysfunction, but not complete destruction. In addition, HFD/STZ (i.e., T2D) resulted in several changes in bone quality that closely mirror those observed in humans, including compromised bone microarchitecture, reduced biomechanical strength, impaired bone material properties, altered bone turnover, and elevated levels of the AGE CML in bone and blood. Furthermore, T2D led to the premature accumulation of senescent osteocytes with a unique proinflammatory signature. These findings highlight the RAGE pathway and senescent cells as potential targets to treat diabetic skeletal fragility.

Shear wave elastography of the median nerve: A mechanical study.

BACKGROUND: Shear wave elastography (SWE) shows promise in peripheral neuropathy evaluation but has potential limitations due to tissue size and heterogeneity. We tested SWE sensitivity to elasticity change and the effect of probe position in a median nerve cadaver model. METHODS: Ten specimens were used to measure median nerve elasticity under increasing loads using SWE and indentation. Measurements were compared using repeated-measures analysis of variance. RESULTS: Indentation and SWE-based longitudinal nerve elasticity increased with tensile loading (P < .01), showing a similar relationship. Acquisition in a transverse plane showed lower values compared with longitudinal measurements, mostly under higher loads (P = .03), as did postdissection elasticity (P = .02). Elasticity did not change when measured proximal to the carpal tunnel. CONCLUSIONS: Longitudinal SWE is sensitive to changes in median nerve elasticity. Measuring elasticity of peripheral nerves noninvasively could elucidate intra-neural pathology related to compression neuropathies, and proof to be of added value as a diagnostic or prognostic tool.

Alterations of Spinal Epidural Stimulation-Enabled Stepping by Descending Intentional Motor Commands and Proprioceptive Inputs in Humans With Spinal Cord Injury.

Background: Regaining control of movement following a spinal cord injury (SCI) requires utilization and/or functional reorganization of residual descending, and likely ascending, supraspinal sensorimotor pathways, which may be facilitated via task-specific training through body weight supported treadmill (BWST) training. Recently, epidural electrical stimulation (ES) combined with task-specific training demonstrated independence of standing and stepping functions in individuals with clinically complete SCI. The restoration of these functions may be dependent upon variables such as manipulation of proprioceptive input, ES parameter adjustments, and participant intent during step training. However, the impact of each variable on the degree of independence achieved during BWST stepping remains unknown. Objective: To describe the effects of descending intentional commands and proprioceptive inputs, specifically body weight support (BWS), on lower extremity motor activity and vertical ground reaction forces (vGRF) during ES-enabled BWST stepping in humans with chronic sensorimotor complete SCI. Furthermore, we describe perceived changes in the level of assistance provided by clinicians when intent and BWS are modified. Methods: Two individuals with chronic, mid thoracic, clinically complete SCI, enrolled in an IRB and FDA (IDE G150167) approved clinical trial. A 16-contact electrode array was implanted in the epidural space between the T11-L1 vertebral regions. Lower extremity motor output and vertical ground reaction forces were obtained during clinician-assisted ES-enabled treadmill stepping with BWS. Consecutive steps were achieved during various experimentally-controlled conditions, including intentional participation and varied BWS (60% and 20%) while ES parameters remain unchanged. Results: During ES-enabled BWST stepping, the knee extensors exhibited an increase in motor activation during trials in which stepping was passive compared to active or during trials in which 60% BWS was provided compared to 20% BWS. As a result of this increased motor activation, perceived clinician assistance increased during the transition from stance to swing. Intentional participation and 20% BWS resulted in timely and purposeful activation of the lower extremities muscles, which improved independence and decreased clinician assistance. Conclusion: Maximizing participant intention and optimizing proprioceptive inputs through BWS during ES-enabled BWST stepping may facilitate greater independence during BWST stepping for individuals with clinically complete SCI. Clinical Trial Registration: ClinicalTrials.gov identifier: NCT02592668.

Calculation of flexor pollicis longus moment arm for wrist motion in a cadaver model validates the tenodesis effect for therapy.

INTRODUCTION: Synergies of fingers and wrist motion have been incorporated into therapies for finger flexor tendon injuries to improve repair outcomes. Similar synergistic therapy strategies have not been well documented for the thumb. PURPOSE OF THE STUDY: The purpose of this study was to investigate the extent to which wrist motion enables a synergistic effect at the thumb in a cadaveric model by measuring flexor pollicis longus excursion and calculating the moment arm of this tendon at the wrist joint. STUDY DESIGN: This is a basic science research. METHODS: Eight fresh-frozen cadaveric arms were obtained from our anatomical bequest program. The proximal arm was fixed in neutral pronation/supination position, and motion of the wrist was guided through either flexion/extension or radial/ulnar deviation. Fingers were fixed in extension, thumb interphalangeal and metacarpophalangeal joints were fixed in neutral extension, and the carpometacarpal joint was fixed at 30° palmar abduction. The flexor pollicis longus tendon was exposed proximal to the wrist crease and connected to a rotary potentiometer to measure tendon excursion. Optical markers were attached to the hand to capture kinematics. Wrists were moved from a neutral position over the range of flexion and extension and then from the neutral position through the range of radial to ulnar deviation. Moment arms were calculated. RESULTS: Moment arm calculation indicated that the flexor pollicis longus acts as a wrist flexor over the entire motion range and as a weak radial deviator at ulnarly-deviated positions. CONCLUSIONS: This study provides a mechanistic rationale for passive interphalangeal joint motion in varying wrist positions when treating thumb flexor tendon injuries, with benefits seen primarily for wrist extension.

The Effect of Proximal Hamate Osteotomy on Carpal Kinematics for Reconstruction of Proximal Pole Scaphoid Nonunion With Avascular Necrosis.

Background: The purpose of this study is to determine the effects of proximal hamate transfer for proximal pole scaphoid reconstruction upon carpal kinematics. Methods: Eight fresh-frozen cadaveric wrists underwent evaluation of their radiocarpal and midcarpal motion after proximal hamate osteotomy. A wrist simulator was used to apply cyclical tension to the flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), and extensor carpi radialis longus and brevis stitched together (ECR). Kinematic motion was captured using Moiré Phase Tracking 3-dimensional motion-tracking sensors (MPT, Metria Innovation, Inc, Milwaukee, Wisconsin) to evaluate the lunocapitate and scapholunate angles for each condition. Results: During wrist flexion-extension and radial-ulnar deviation, there were no statistically significant differences about the lunocapitate or scapholunate axis between the intact and post-hamate osteotomy conditions. Conclusions: The harvest of the proximal hamate for proximal pole scaphoid reconstruction does not appear to adversely affect wrist kinematics.

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.

Speckle Tracking of Tendon Displacement in the Carpal Tunnel: Improved Quantification Using Singular Value Decomposition.

Ultrasound is a real-time image modality enabling the analysis of tendon dynamics for the diagnosis of carpal tunnel syndrome. Automatic tendon displacement quantification algorithms based on speckle tracking generally suffer from underestimation due to stationary background present in the tendon region. We propose an improved quantification method using singular value decomposition (SVD) filtering to suppress the clutter. The accuracy of our improved speckle tracking (IST) method was validated against a ground truth and compared to the accuracy of our original block matching (OBM) algorithm and commercial tissue tracking (CTT) software. The methods were evaluated in experiments involving six human cadaver arms. The ground-truth displacements were generated by tracking metal markers inserted in the tendons. The relative displacement errors with respect to the ground truth for IST were 12 ± 16.9%, which was significantly lower than for OBM (19.7 ± 20.8%) and for CTT (25.8 ± 18.4%). These findings show that SVD filtering improves the tendon tracking by reducing underestimation due to clutter.

Publisher Correction: Neuromodulation of lumbosacral spinal networks enables independent stepping after complete paraplegia.

In the version of this article originally published, Dimitry G. Sayenko's affiliations were not correct. The following affiliation for this author was missing: Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, USA. This affiliation has been added for the author, and the rest of the affiliations have been renumbered accordingly. The error has been corrected in the HTML and PDF versions of this article.