Evaluation of pre-hospital cannabis exposure and hospital opioid utilization in a trauma population: A retrospective cohort.

PURPOSE: Cannabis utilization has increased over time for recreational and medical purposes due to its legalization or decriminalization. The effects of cannabis use on opioid utilization are not well understood. The primary objective was to evaluate the total opioid utilization, measured in morphine milligram equivalents (MME), in hospitalized trauma patients that tested positive for tetrahydrocannabinol (THC) on a urine drug screen (UDS). METHODS: This was a retrospective, cohort study in a level 1 trauma center between 10/17/17 and 12/31/19. Adult trauma patients (aged 15 years and older) who had a UDS completed within 48 h of hospital arrival were eligible for inclusion. Patients were excluded for a hospitalization >14 days, death within 24 h, severe alcohol withdrawal, prescribed cannabinoids, high daily opioid use prior-to-arrival, or transitioned to hospice or palliative care. Group assignments were determined based on the presence or absence of THC on the UDS. RESULTS: The analysis included 750 patients with 160 (21 %) THC positive patients. The population were primarily male (64.6 %), median age of 56 years [IQR 35-72], with blunt (93 %) injuries from motor vehicle crash or falls (79 %). The THC group was more likely to have other substances present, including amphetamines, benzodiazepines, opiates, and cocaine. The THC group had a higher median injury severity score (10 [IQR 5-17] vs. 9 [5-14], p = 0.0056), and maximum abbreviated injury score (3 [IQR 2-3] vs. 2 [IQR 2-3], p = 0.0009). The THC group had a total higher median opioid utilization during the hospitalization (155 [IQR 68-367] vs. 62 [IQR 13-175] MME; p < 0.0001), which included higher opioid use in the emergency department, floor, and intensive care unit. There were no significant differences in secondary outcomes except the THC group was more likely to receive an opioid prescription at discharge and more likely to require mechanical ventilation. Based on multivariable regression analyses, other variables were associated with increased opioid utilization. CONCLUSION: Pre-existing THC exposure may be associated with an increased hospital opioid utilization in a trauma population. However, other variables may also play a role in opioid utilization.

Development and validation of a delirium risk prediction model using a modified version of the Delirium Elderly at Risk (mDEAR) screen in hospitalized patients aged 65 and older: A medical record review.

Most delirium risk prediction models are cumbersome to use, time consuming to complete, and require education ensure accuracy. The purpose of this study was to develop and validate a risk prediction model using routinely assessed risk factors predictive of delirium including: cognitive impairment, ≥80-years old, functional dependence, sensory impairment, and chronic substance use. This retrospective study included 7999 encounters of hospitalized patients aged 65-years or older admitted from 1/1/2019 to 12/31/2019. Various models were compared, with the best tested for validation. A model, where cognitive impairment was worth 2-points and a threshold of 3-points to predict delirium, was determined to be the best model and was validated with an area-under Receiver-Operating-Characteristic curve=0.7126. Management of delirium could be enhanced by integrating a nursing admission delirium risk screening process into the workflow, triggering initiation of prevention interventions and prompt assessment for signs and symptoms of delirium for those at high risk.

Does Breast Cancer Subtype Impact Margin Status in Patients Undergoing Partial Mastectomy?

BACKGROUND: Molecular subtype in invasive breast cancer guides systemic therapy. It is unknown whether molecular subtype should also be considered to tailor surgical therapy. The present investigation was designed to evaluate whether breast cancer subtype impacted surgical margins in patients with invasive breast cancer stage I through III undergoing breast-conserving therapy. METHODS: Data from 2 randomized trials evaluating cavity shave margins (CSM) on margin status in patients undergoing partial mastectomy (PM) were used for this analysis. Patients were included if invasive carcinoma was present in the PM specimen and data for all 3 receptors (ER, PR, and HER2) were known. Patients were classified as luminal if they were ER and/or PR positive; HER2 enriched if they were ER and PR negative but HER2 positive; and TN if they were negative for all 3 receptors. The impact of subtype on the margin status was evaluated at completion of standard PM, prior to randomization to CSM versus no CSM. Non-parametric statistical analyses were performed using SPSS Version 26. RESULTS: Molecular subtype was significantly correlated with race (P = .011), palpability (P = .007), and grade (P < .001). Subtype did not correlate with Hispanic ethnicity (P = .760) or lymphovascular invasion (P = .756). In this cohort, the overall positive margin rate was 33.7%. This did not vary based on molecular subtype (positive margin rate 33.7% for patients with luminal tumors vs 36.4% for those with TN tumors, P = .425). DISCUSSION: Molecular subtype does not predict margin status. Therefore, molecular subtype should not, independent of other factors, influence surgical decision-making.

Prior Admissions as a Risk Factor for Readmission in Patients Surgically Treated for Femur Fractures: Implications for a Potential Hip Fracture Bundle.

INTRODUCTION: Hip fractures are a significant economic burden to our healthcare system. As there have been efforts made to create an alternative payment model for hip fracture care, it will be imperative to risk-stratify reimbursement for these medically comorbid patients. We hypothesized that patients readmitted to the hospital within 90 days would be more likely to have a recent previous hospital admission, prior to their injury. Patients with a recent prior admission could therefore be considered higher risk for readmission and increased cost. METHODS: A retrospective chart review identified 598 patients who underwent surgical fixation of a hip or femur fracture. Data on readmissions within 90 days of surgical procedure and previous admissions in the year prior to injury resulting in surgical procedure were collected. Logistic regression analysis was used to determine if recent prior admission had increased risk of 90-day readmission. A subgroup analysis of geriatric hip fractures and of readmitted patients were also performed. RESULTS: Having a prior admission within one year was significantly associated (p < 0.0001) for 90-day readmission. Specifically, logistic regression analysis revealed that a prior admission was significantly associated with 90-day readmission with an odds ratio of 7.2 (95% CI: 4.8-10.9). DISCUSSION: This patient population has a high rate of prior hospital admissions, and these prior admissions were predictive of 90-day readmission. Alternative payment models that include penalties for readmissions or fail to apply robust risk stratification may unjustly penalize hospital systems which care for more medically complex patients. CONCLUSIONS: Hip fracture patients with a recent prior admission to the hospital are at an increased risk for 90-day readmission. This information should be considered as alternative payment models are developed for hip fracture care.

Bariatric Enhanced Recovery Protocol: a Community Quality Perspective.

INTRODUCTION: Bariatric enhanced recovery protocols can decrease length of stay (LOS) and hospital costs without compromising patient safety. Increased data is needed to compare patient outcomes before and after application of enhanced recovery pathways. We present a bariatric enhanced recovery protocol (BERP) at a community hospital. The objectives were to decrease hospital LOS and reduce schedule II substance use (medications with a high potential for abuse, potentially resulting in psychological or physical dependence), without compromising patient safety. METHODS: This was a combined retrospective and prospective analysis of all patients undergoing bariatric surgery by two surgeons from September 2016 to April 2018. Mann-Whitney U, Pearson chi-square, and Fisher's exact tests were used to compare demographics, comorbidities, and outcomes. RESULTS: Two hundred patients were evaluated. Overall median (interquartile range) age was 43.0 (36.0-54.0) years and body mass index (BMI) was 45.0 (40.6-50.3) kg/m2. Pre-protocol mean hospital LOS was 2.3 days while enhanced recovery protocol patients mean LOS was 1.4 days (p < 0.001). Sixty-five percent of BERP patients were discharged on hospital day 1, while no patients prior to the protocol were discharged before hospital day 2. Only 9% of BERP patients were discharged with schedule II medications, compared to 100% of the pre-protocol patients (p < 0.001). Intraoperative, in-hospital, and 30-day complication rates were not statistically significant between the two groups. CONCLUSION: Community hospitals can reduce length of stay and narcotic prescribing without compromising safety-related outcomes. Significant reductions in the amount of schedule II medications can be achieved when using multimodal enhanced recovery protocol approaches.

Intravenous Iron May Improve Outcomes in Elderly Patients With Operative Hip Fractures.

INTRODUCTION: Hip fractures are common injuries with high morbidity and mortality rates. These patients often become anemic and require allogenic blood transfusion. Transfusions are costly with potential complications. This study examines the effect of intravenous (IV) iron on patients with hip fractures, undergoing surgery within 48 hours, and being treated with a highly restrictive transfusion protocol. MATERIALS AND METHODS: A retrospective chart review performed on patients admitted to a level 1 tertiary care center with fractures of the proximal femur from December 2015 to December 2017 included 239 patients. Patients who received 300 mg of IV iron when their hemoglobin fell below 11 g/dL were compared to a control group of patients who never received IV iron with respect to transfusion rate, 30-day readmission rate, nosocomial infections, length of stay, and hospital costs. RESULTS: There were no significant differences in transfusion rates (P = .118). There was a trend toward decreased length of stay (P = .063) and 30-day readmission rates (P = .051) with a 59% reduction in the odds of 30-day readmission when a patient received IV iron. There were no differences in nosocomial infection rates or cost of hospitalization. DISCUSSION: This study presents a compelling argument for further research regarding the use of IV iron in elderly patients undergoing surgery for a hip fracture. Length of stay and transfusion rates are increased in patients with intertrochanteric fractures and undergoing intramedullary nailing. A higher number of these patients in the IV iron group may have falsely increased these rates. A prospective, randomized, controlled trial is needed to assess the true effects of perioperative IV iron. CONCLUSIONS: This study showed no significant benefit to IV iron use in elderly patients undergoing surgical treatment of hip fracture. The decrease in 30-day readmission rate should be further examined with a prospective randomized controlled trial.

Safety and Communication in the Operating Room: A Safety Questionnaire After the Implementation of a Blood-Borne Pathogen Exposure Checkpoint in the Surgical Safety Checklist Preprocedure Time-Out.

INTRODUCTION: The Surgical Safety Checklist (SSC) decreases patient morbidity and mortality and improves operating room (OR) communication. However, the SSC does not currently include any discussion on employee safety. One institution has implemented a blood-borne pathogen exposure (BBPE) checkpoint in the SSC in order to improve employee safety and to further improve communication. The aim of this study was to determine if the implementation of a BBPE checkpoint improved caregiver safety and communication in the OR. METHODS: This was a multidisciplinary prospective survey study in which an anonymous questionnaire was distributed to all OR personnel who handle sharps. Survey responses were analyzed for demographics and BBPE safety attitudes. The frequency of reported BBPE incidents collected from quality improvement data 12 months before and after the implementation of the BBPE checkpoint were reviewed. RESULTS: Caregivers feel safer in the OR with the BBPE checkpoint (p < 0.001). Communication was improved. Compliance in trauma surgeries was less than elective. Reported BBPE incidents were significantly decreased based on quality improvement data (p = 0.045). CONCLUSION: The BBPE checkpoint was implemented in the SSC at one institution in order to emphasize employee safety and improve communication. The results shed light on the attitudes of OR personnel by suggesting an improvement in safety and communication. In addition, there has been decrease of reported BBPE incidents among OR personnel. Universal implementation of a BBPE checkpoint could improve provider safety and communication in all ORs.

Dynamic tracking influenced by anatomy following medial patellofemoral ligament reconstruction: Computational simulation.

BACKGROUND: Continued patellar instability can occur following medial patellofemoral ligament (MPFL) reconstruction. Computational simulation of function was used to investigate the influence of the lateral position of the tibial tuberosity, trochlear dysplasia and patella alta on lateral patellar tracking following MPFL reconstruction. METHODS: Multibody dynamic simulation models were developed to represent nine knees being treated for recurrent patellar instability. Knee extension against gravity and dual limb squatting were simulated with and without simulated MPFL reconstruction. Graft resting lengths were set to allow 10mm and five millimeters of patellar lateral translation at 30° of knee flexion. The bisect offset index, lateral tibial tuberosity to posterior cruciate ligament tibial attachment (TT-PCL) distance, lateral trochlear inclination, and Caton-Deschamps index were quantified at every five degrees of knee flexion to characterize lateral tracking, lateral position of the tibial tuberosity, trochlear dysplasia, and patella alta, respectively. For the pre-operative and post-operative conditions and each type of motion, bisect offset index was correlated with the anatomical parameters using stepwise multivariate linear regression. RESULTS: For both motions, the pre-operative and post-operative bisect offset indices were significantly correlated with lateral trochlear inclination and lateral TT-PCL distance. For both motions, the adjusted r2 decreased with MPFL reconstruction, but was still approximately 0.5 for MPFL reconstruction allowing five millimeters of lateral translation. CONCLUSION: MPFL reconstruction decreases but does not eliminate lateral maltracking related to trochlear dysplasia and a lateralized tibial tuberosity. Patients with these pathologies are likely at the highest risk for instability related to maltracking following MPFL reconstruction.

Allowing one quadrant of patellar lateral translation during medial patellofemoral ligament reconstruction successfully limits maltracking without overconstraining the patella.

PURPOSE: Graft tensioning during medial patellofemoral ligament (MPFL) reconstruction typically allows for lateral patellar translation within the trochlear groove. Computational simulation was performed to relate the allowed patellar translation to patellofemoral kinematics and contact pressures. METHODS: Multibody dynamic simulation models were developed to represent nine knees with patellar instability. Dual limb squatting was simulated representing the pre-operative condition and simulated MPFL reconstruction. The graft was tensioned to allow 10, 5, and 0 mm of patellar lateral translation at 30° of knee flexion. The patellofemoral contact pressure distribution was quantified using discrete element analysis. RESULTS: For the 5 and 10 mm conditions, patellar lateral shift decreased significantly at 0° and 20°. The 0 mm condition significantly decreased lateral shift for nearly all flexion angles. All graft conditions significantly decreased lateral tilt at 0°, with additional significant decreases for the 5 and 0 mm conditions. The 0 mm condition significantly increased the maximum medial pressure at multiple flexion angles, increasing by 57% at 30°, but did not alter the maximum lateral pressure. CONCLUSIONS: Allowing 5 to 10 mm of patellar lateral translation limits lateral maltracking, thereby decreasing the risk of post-operative recurrent instability. Allowing no patellar translation during graft tensioning reduces maltracking further, but can overconstrain the patella, increasing the pressure applied to medial patellar cartilage already fibrillated or eroded from an instability episode.

Comparison of Clopidogrel With Prasugrel and Ticagrelor in Patients With Acute Coronary Syndrome: Clinical Outcomes From the National Cardiovascular Database ACTION Registry.

BACKGROUND: We aimed to compare the clinical outcomes of clopidogrel, prasugrel, and ticagrelor in clinical practice using the National Cardiovascular Database ACTION Registry®. Treatment guidelines for patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention recommend dual antiplatelet therapy (DAPT) for 12 months. Few clinical trials have compared the safety and efficacy of clopidogrel with that of newer antiplatelet therapies. METHODS: A retrospective study of patients hospitalized for ACS at Cleveland Clinic Akron General was conducted. Data elements included detailed medical history and clinical outcomes during hospital stay. The primary outcome was a composite of major clinical events (cardiogenic shock, atrial fibrillation, ventricular fibrillation, ventricular tachycardia, heart failure, bleeding, and mechanical ventilation). The independent variable was the type of DAPT. Statistical analyses were performed using Chi-square and Mann-Whitney U tests. A post-hoc analysis was performed to compare between the antiplatelet drugs head-to-head. RESULTS: Subjects (n = 1,388) admitted between January 2011 and March 2016 with ACS and treated with clopidogrel, prasugrel, or ticagrelor were included in the study. Mean age was 65 ± 14 years and 46% had ST-segment elevation myocardial infarction. Prasugrel administration within 24 h was associated with a lower incidence of the composite outcome (P = 0.049), bleeding (P = 0.028), and heart failure (P = 0.002). CONCLUSION: There was a significant difference between the type of antiplatelet drug and clinical outcomes in ACS patients who were treated with DAPT. Observations from current study may provide important information for prescribers in clinical decision-making.

In Vitro Comparison of Two Barbed Suture Configurations for Flexor Tendon Repair.

Purpose The current study compares the strength of a previously studied technique for flexor tendon repair with barbed sutures to an experimental approach that aligns all the barbs to oppose distraction. Methods Twelve flexor tendons from cadaveric specimens were mechanically tested following repair of simulated zone II tendon injuries. Two repair techniques utilizing barbed sutures were studied: the Marrero-Amadeo four-core barbed suture approach and the experimental configuration with all barbs on four cores opposing distraction. Maximum applied load at failure, that is, ultimate load, and 2-mm gap force were compared between the two repair techniques, both as raw values and after normalization to cross-sectional area of the intact tendon. Statistical testing was performed using t -tests and Mann-Whitney U -tests, where appropriate, with a significance level of 0.05. Results The ultimate loads, raw (58.2 N) and normalized (4.8 N/mm 2 ), were significantly larger for the Marrero-Amadeo repair than the proposed experimental approach (35.6 N and 2.7 N/mm 2 ; p < 0.05). No significant differences were identified for 2-mm gap force. Conclusion The innovation of suturing to align all barbs to oppose distraction does not improve strength of the repaired tendon. The Marrero-Amadeo technique was found to have superior strength for use in traumatic zone II flexor tendon injuries.

In vivo tissue interaction between the transverse carpal ligament and finger flexor tendons.

The transverse carpal ligament (TCL) is a component of the flexor pulley system of the wrist, keeping the flexor tendons in place by resisting their volar displacement. The purpose of this study was to investigate the in vivo biomechanical interaction between the TCL and flexor tendons in response to tendon tensioning with the wrist at various postures. In eight healthy subjects, the flexor digitorum superficialis and profundus tendons were tensioned by isometrically applying loads (5, 10, and 15N) to the index finger while the wrist posture was at 20° extension, neutral, 20° flexion, and 40° flexion. The TCL and flexor tendons were imaged at the distal carpal tunnel cross section using ultrasound. The volar-dorsal positions of the tendons, TCL arch height, and TCL-tendon distances were calculated. With increasing wrist flexion, the flexor tendons moved volarly, the TCL arch height increased, and the TCL-tendon distances decreased, indicating that the flexor tendons contacted the TCL and pushed it volarly. The TCL-tendon interaction was amplified by the combination of finger loading and wrist flexion. This study provides in vivo evidence of the biomechanical interaction between the TCL and flexor tendons. Repetitive TCL-tendon interactions may implicate the interacting tissues and the median nerve resulting in tissue maladaptation and nerve compression.

Three-dimensional stiffness of the carpal arch.

The carpal arch of the wrist is formed by irregularly shaped carpal bones interconnected by numerous ligaments, resulting in complex structural mechanics. The purpose of this study was to determine the three-dimensional stiffness characteristics of the carpal arch using displacement perturbations. It was hypothesized that the carpal arch would exhibit an anisotropic stiffness behavior with principal directions that are oblique to the conventional anatomical axes. Eight (n=8) cadavers were used in this study. For each specimen, the hamate was fixed to a custom stationary apparatus. An instrumented robot arm applied three-dimensional displacement perturbations to the ridge of trapezium and corresponding reaction forces were collected. The displacement-force data were used to determine a three-dimensional stiffness matrix using least squares fitting. Eigendecomposition of the stiffness matrix was used to identify the magnitudes and directions of the principal stiffness components. The carpal arch structure exhibited anisotropic stiffness behaviors with a maximum principal stiffness of 16.4±4.6N/mm that was significantly larger than the other principal components of 3.1±0.9 and 2.6±0.5N/mm (p<0.001). The principal direction of the maximum stiffness was pronated within the cross section of the carpal tunnel which is accounted for by the stiff transverse ligaments that tightly bind distal carpal arch. The minimal principal stiffness is attributed to the less constraining articulation between the trapezium and scaphoid. This study provides advanced characterization of the wrist׳s three-dimensional structural stiffness for improved insight into wrist biomechanics, stability, and function.

Thickness and Stiffness Adaptations of the Transverse Carpal Ligament Associated with Carpal Tunnel Syndrome.

The purpose of this study was to investigate the morphological and mechanical properties of the transverse carpal ligament (TCL) in patients with carpal tunnel syndrome (CTS). Thickness and stiffness of the TCL in eight female CTS patients and eight female control subjects were examined using ultrasound imaging modalities. CTS patients had a 30.9% thicker TCL than control subjects. There was no overall difference in TCL stiffness between the two groups, but the radial TCL region was significantly stiffer than the ulnar region within the CTS group and such a regional difference was not found for the controls. The increased thickness and localized stiffness of the TCL for CTS patients may contribute to CTS symptoms due to reduction in carpal tunnel space and compliance. Advancements in ultrasound technology provide a means of understanding CTS mechanisms and quantifying the morphological and mechanical properties of the TCL in vivo.

Elliptical Morphology of the Carpal Tunnel Cross Section.

Although the carpal tunnel is known for its anatomical constituents, its morphology is not well recognized. The aim of this study was to investigate the morphometric properties of the carpal tunnel and its surrounding structures. Magnetic resonance, cross-sectional images of the distal carpal tunnel were collected from eight cadaveric hands. Morphological analyses were performed for the cross sections of the carpal tunnel, interior carpus boundary, and exterior carpus boundary. The specimens had a carpal arch width and height of 23.9 ± 2.9 mm and 2.2 ± 0.9 mm, respectively. The carpal tunnel, interior carpus boundary, and exterior carpus boundary had perimeters of 54.8 ± 4.5 mm, 68.5 ± 7.0 mm, and 130.6 ± 11.8 mm, respectively, and areas of 183.5 ± 30.1 mm2, 240.7 ± 40.2 mm2, and 1002.3 ± 183.7 mm2, respectively. The cross sections were characterized by elliptical fitting with aspect ratios of 1.96 ± 0.15, 1.96 ± 0.19, and 1.76 ± 0.19 for the carpal tunnel, interior carpus boundary, and exterior carpus boundary, respectively. The major axis of the boundaries increased in pronation angle, relative to the hamate-trapezium axis, for the exterior carpus (6.0 ± 3.0°), interior carpus (8.2 ± 3.2°), and carpal tunnel (15.9 ± 2.2°). This study advances our understanding of the structural anatomy of the carpal tunnel, and the morphological information is valuable in the identification of structural abnormality, assistance of surgical planning, and evaluation of treatment of effects.

Morphological and positional changes of the carpal arch and median nerve during wrist compression.

BACKGROUND: The carpal tunnel is a fibro-osseous structure containing the median nerve and flexor tendons. Its cross-sectional area has been shown to increase during compressive force application to the carpal bones in modeling and in vitro studies. The purpose of this study was to investigate the morphological and positional changes of the carpal arch and median nerve while in vivo compressive force was applied in the radioulnar direction across the wrist. METHODS: Ultrasound images of the carpal tunnel and its contents were captured for 11 healthy, female volunteers at the distal tunnel level prior to force application and during force application of 10 and 20N. FINDINGS: With applied force, the carpal arch width significantly decreased, while the carpal arch height and area significantly increased (P<0.001). The median nerve shape became more rounded as the compressive force magnitude increased, reflected by decreases in the nerve's flattening ratio and increases in its circularity (P<0.001). The applied force also resulted in nerve displacement in the radial-volar direction. INTERPRETATION: This study demonstrates that noninvasively applying radioulnar compressive force across the wrist may potentially provide relief of median nerve compression to patients suffering from carpal tunnel syndrome.

Elliptical morphology of the carpal tunnel cross section

Although the carpal tunnel is known for its anatomical constituents, its morphology is not well recognized. The aim of this study was to investigate the morphometric properties of the carpal tunnel and its surrounding structures. Magnetic resonance and cross-sectional images of the distal carpal tunnel were collected from eight cadaveric hands. Morphological analyses were performed for the cross sections of the carpal tunnel, interior carpus boundary, and exterior carpus boundary. The specimens had a carpal arch width and height of 23.9 ± 2.9 mm and 2.2 ± 0.9 mm, respectively. The carpal tunnel, interior carpus boundary, and exterior carpus boundary had perimeters of 54.8 ± 4.5 mm, 68.5 ± 7.0 mm, and 130.6 ± 11.8 mm, respectively, and areas of 183.5 ± 30.1 mm2, 240.7 ± 40.2 mm2, and 1002.3 ± 183.7 mm2, respectively. The cross sections were characterized by elliptical fitting with aspect ratios of 1.96 ± 0.15, 1.96 ± 0.19, and 1.76 ± 0.19 for the carpal tunnel, interior carpus boundary, and exterior carpus boundary, respectively. The major axis of the boundaries increased in pronation angle, relative to the hamate-trapezium axis, for the exterior carpus (6.0 ± 3.0º), interior carpus (8.2 ± 3.2º), and carpal tunnel (15.9 ± 2.2º). This study advances our understanding of the structural anatomy of the carpal tunnel, and the morphological information is valuable in the identification of structural abnormality, assistance of surgical planning, and evaluation of treatment of effects

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Carpal Tunnel Cross-Sectional Area Affected by Soft Tissues Abutting the Carpal Bones.

The carpal tunnel accommodates free movement of its contents, and the tunnel's cross-sectional area is a useful morphological parameter for the evaluation of the space available for the carpal tunnel contents and of potential nerve compression in the tunnel. The osseous boundary of the carpal bones as the dorsal border of the carpal tunnel is commonly used to determine the tunnel area, but this boundary contains soft tissues such as numerous intercarpal ligaments and the flexor carpi radialis tendon. The aims of this study were to quantify the thickness of the soft tissues abutting the carpal bones and to investigate how this soft tissue influences the calculation of the carpal tunnel area. Magnetic resonance images were analyzed for eight cadaveric specimens. A medical balloon with a physiological pressure was inserted into an evacuated tunnel to identify the carpal tunnel boundary. The balloon-based (i.e. true carpal tunnel) and osseous-based carpal tunnel boundaries were extracted and divided into regions corresponding to the hamate, capitate, trapezoid, trapezium, and transverse carpal ligament (TCL). From the two boundaries, the overall and regional soft tissue thicknesses and areas were calculated. The soft tissue thickness was significantly greater for the trapezoid (3.1±1.2mm) and trapezium (3.4±1.0mm) regions than for the hamate (0.7±0.3mm) and capitate (1.2±0.5mm) regions. The carpal tunnel area using the osseous boundary (243.0±40.4mm2) was significantly larger than the balloon-based area (183.9±29.7mm2) with a ratio of 1.32. In other words, the carpal tunnel area can be estimated as 76% (= 1/1.32) of the osseous-based area. The abundance of soft tissue in the trapezoid and trapezium regions can be attributed mainly to the capitate-trapezium ligament and the flexor carpi radialis tendon. Inclusion of such soft tissue leads to overestimations of the carpal tunnel area. Correct quantification of the carpal tunnel area aids in examining carpal tunnel stenosis as a potential risk factor for median nerve compression.

Narrowing carpal arch width to increase cross-sectional area of carpal tunnel--a cadaveric study.

BACKGROUND: Carpal tunnel morphology plays an essential role in the etiology and treatment of carpal tunnel syndrome. The purpose of this study was to observe the morphological changes of the carpal tunnel as a result of carpal arch width narrowing. It was hypothesized that carpal arch width narrowing would result in increased height and area of the carpal arch. METHODS: The carpal arch width of eight cadaveric hands was narrowed by a custom apparatus and cross-sectional ultrasound images were acquired. The carpal arch height and area were quantified as the carpal arch width was narrowed. Correlation and regression analyses were performed for the carpal arch height and area with respect to the carpal arch width. FINDINGS: The carpal tunnel became more convex as the carpal arch width was narrowed. The initial carpal arch width, height, and area were 25.7 (SD1.9) mm, 4.1 (SD0.6) mm, and 68.5 (SD14.0) mm(2), respectively. The carpal arch height and area negatively correlated with the carpal arch width, with correlation coefficients of -0.974 (SD0.018) and -0.925 (SD0.034), respectively. Linear regression analyses showed a 1mm narrowing of the carpal arch width resulted in proportional increases of 0.40 (SD0.14) mm in the carpal arch height and 4.0 (SD2.2) mm(2) in the carpal arch area. INTERPRETATION: This study demonstrates that carpal arch width narrowing leads to increased carpal arch height and area, a potential mechanism to reduce the mechanical insult to the median nerve and relieve symptoms associated with carpal tunnel syndrome.

Pressure-morphology relationship of a released carpal tunnel.

We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p < 0.001), with an increase of >62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p < 0.05). As carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery.