Wrist Motion Assessment in Tennis Players using Three-Dimensional Motion Capture and Dynamic Electromyography.

Background Tennis players often present with ulnar-sided wrist pain, which may reflect repetitive stress and/or faulty mechanics. There is a role for investigating the biomechanics of tennis strokes and how they may relate to wrist pathology. The purpose of this study was to investigate whether three-dimensional motion capture technology and dynamic electromyography (EMG), when used to study groundstrokes in elite junior tennis players, reveals patterns of upper extremity motion that may correlate with the development of clinically relevant pathology. Case Description Three-dimensional kinematic and EMG data were collected from two United States Tennis Association-ranked adolescent tennis players during groundstrokes. There were several observed differences in the two players' degree and timing of pronation/supination, ulnar/radial deviation, and flexion/extension during their strokes. Clinical Significance Advanced motion capture technology facilitates a nuanced understanding of complex movements involved in groundstroke production. This methodology may be useful for identifying athletes who are at risk for injury and guiding rehabilitation for players experiencing pain. Level of Evidence IV.

Optimal Distal Tendon Insertion Point for Elbow Flexion in Free-Functioning Gracilis Muscle Transfer for Panbrachial Plexus Injuries: A Cadaveric Study.

PURPOSE: Following pan-brachial plexus injuries, restoration of elbow flexion is widely accepted as the reconstructive priority. A gracilis free functioning muscle transfer (FFMT) can be used to restore elbow flexion alone with insertion into the biceps brachii (BIC) or brachioradialis (BRD) tendons or restore combined elbow and finger flexion with a more distal insertion into the flexor digitorum profundus (FDP) tendons. Using cadaveric experiments, we determined the peak instantaneous moment arm for each insertion option. METHODS: Six simulated gracilis transfer surgeries were performed using both arms of three fresh-frozen full body cadaveric specimens (age: 79 + 10 years. 2 female). The gracilis muscles from both legs were harvested and transferred to the contralateral upper extremity. The elbow was manually moved through three flexion-extension cycles while the instantaneous moment arm was calculated from measurements of gracilis excursion and elbow joint angle for the three distal insertion sites. RESULTS: Peak instantaneous moment arm for all three insertions occurred at an elbow angle between 83° to 92° with a magnitude ranging from 33 mm to 54 mm. The more distal (FDP/BRD) insertions produced a significantly greater (∼1.5 times) peak elbow flexion instantaneous moment arm compared to the BIC insertion. CONCLUSIONS: Based on the instantaneous moment arm, the gracilis FFMT distal insertion locations could result in greater reconstructed elbow flexion strength. In addition, direct measurement of the shape and magnitude of the moment arm curve for differing insertion sites allows high resolution surgical planning and model testing. CLINICAL RELEVANCE: This study presents the first direct experimental quantification of the gracilis FFMT instantaneous moment arm. The experimental evidence supports the use of FDP/BRD insertion locations by providing a quantitative explanation for the increased elbow flexion torque observed clinically in patients with a gracilis FFMT and distal FDP insertion.

Objective assessment of patients with idiopathic normal pressure hydrocephalus following ventriculoperitoneal shunt placement using activity-monitoring data: pilot study.

OBJECTIVE: Idiopathic normal pressure hydrocephalus (iNPH) results in significant morbidity in the elderly with symptoms of dementia, gait instability, and urinary incontinence. In well-selected patients, ventriculoperitoneal shunt (VPS) placement often results in clinical improvement. Most postshunt assessments of patients rely on subjective scales. The goal of this study was to assess the utility of remote activity monitoring to provide objective evidence of gait improvement following VPS placement for iNPH. METHODS: Patients with iNPH were prospectively enrolled and fitted with 5 activity monitors (on the hip and bilateral thighs and ankles) that they wore for 4 days preoperatively within 30 days of surgery and for 4 days within 30 days postoperatively. Monitors collected continuous data for number of steps, cadence, body position (upright, prone, supine, and lateral decubitus), gait entropy, and the proportion of each day spent active or static. Data were retrieved from the devices and a comparison of pre- and postoperative movement assessment was performed. The gait data were also correlated with formal clinical gait assessments before and after lumbar puncture and with motion analysis laboratory testing at baseline and 1 month and 1 year after VPS placement. RESULTS: Twenty patients fulfilled the inclusion and exclusion criteria (median age 76 years). The baseline median number of daily steps was 1929, the median percentage of the day spent inactive was 70%, the median percentage of the day with a static posture was 95%, the median gait velocity was 0.49 m/sec, and the median number of steps required to turn was 8. There was objective improvement in median entropy from pre- to postoperatively, increasing from 0.6 to 0.8 (p = 0.002). There were no statistically significant differences for any of the remaining variables measured by the activity monitors when comparing the preoperative to the 1-month postoperative time point. All variables from motion analysis testing showed statistically significant differences or a trend toward significance at 1 year after VPS placement. Among the significantly correlated variables at baseline, cadence was inversely correlated with percentage of gait cycle spent in the support phase (contact with ground vs swing phase). CONCLUSIONS: This pilot study suggests that activity monitoring provides an early objective measure of improvement in gait entropy after VPS placement among patients with iNPH, although a more significant improvement was noted on the detailed clinical gait assessments. Further long-term studies are needed to determine the utility of remote monitoring for assessing gait improvement following VPS placement.

Direct intraoperative measurement of isometric contractile properties in living human muscle.

Skeletal muscle's isometric contractile properties are one of the classic structure-function relationships in all of biology allowing for extrapolation of single fibre mechanical properties to whole muscle properties based on the muscle's optimal fibre length and physiological cross-sectional area (PCSA). However, this relationship has only been validated in small animals and then extrapolated to human muscles, which are much larger in terms of length and PCSA. The present study aimed to measure directly the in situ properties and function of the human gracilis muscle to validate this relationship. We leveraged a unique surgical technique in which a human gracilis muscle is transferred from the thigh to the arm, restoring elbow flexion after brachial plexus injury. During this surgery, we directly measured subject specific gracilis muscle force-length relationship in situ and properties ex vivo. Each subject's optimal fibre length was calculated from their muscle's length-tension properties. Each subject's PCSA was calculated from their muscle volume and optimal fibre length. From these experimental data, we established a human muscle fibre-specific tension of 171 kPa. We also determined that average gracilis optimal fibre length is 12.9 cm. Using this subject-specific fibre length, we observed an excellent fit between experimental and theorical active length-tension curves. However, these fibre lengths were about half of the previously reported optimal fascicle lengths of 23 cm. Thus, the long gracilis muscle appears to be composed of relatively short fibres acting in parallel that may not have been appreciated based on traditional anatomical methods. KEY POINTS: Skeletal muscle's isometric contractile properties represent one of the classic structure-function relationships in all of biology and allow scaling single fibre mechanical properties to whole muscle properties based on the muscle's architecture. This physiological relationship has only been validated in small animals but is often extrapolated to human muscles, which are orders of magnitude larger. We leverage a unique surgical technique in which a human gracilis muscle is transplanted from the thigh to the arm to restore elbow flexion after brachial plexus injury, aiming to directly measure muscles properties in situ and test directly the architectural scaling predictions. Using these direct measurements, we establish human muscle fibre-specific tension of ∼170 kPa. Furthermore, we show that the gracilis muscle actually functions as a muscle with relatively short fibres acting in parallel vs. long fibres as previously assumed based on traditional anatomical models.

Muscle activation for targeted elbow force production following surgical reconstruction in adults with brachial plexus injury.

Nerve transfer or grafting surgery to restore elbow flexion in peripheral nerve injuries has been an effective technique, but alters neuromuscular control compared with healthy individuals. This study compared neuromuscular control in the elbow flexors of 11 unimpaired control subjects and 11 adult patients with traumatic brachial plexus injury who underwent a nerve transfer or grafting procedure to the biceps motor branch to restore elbow flexion. The subjects performed a series of trials to generate a specific percentage of their maximum elbow torque. Each trial had an increasing and decreasing stairstep torque pattern that the subjects were asked to match. The amount of time that the subject's elbow torque was maintained within 5% of the target torque was calculated. The hypothesis was that there was a significant difference in the neuromuscular control between the two groups during elbow isometric torque generation. A secondary hypothesis was that a relationship existed between the neuromuscular control and the torque level for each group. The results demonstrated that neuromuscular control was different between the groups and there were significant differences in how torque levels are generated. The control group more easily modulated their myoelectric activation and achieved greater neuromuscular control variability with varying torque demand. The nerve transfer or grafting group could not modulate their myoelectric activation with changing torque demands. Further studies focusing on the improvement of neuromuscular control are needed to optimize functional outcomes in nerve injury patients.

Outcome of bracing vs. surgical treatment in adolescents with idiopathic scoliosis based on device measured daily physical activity: a prospective pilot study.

Adolescent idiopathic scoliosis (AIS) can be treated with bracing or surgery, which may affect patient's physical activity (PA). However, there are limited objective assessments of PA in patients with AIS. This study aims to compare the outcome of spinal bracing vs. surgery in patients with AIS based on a device that measured daily PA. In total 24 patients with AIS participated, including 12 patients treated with bracing and 12 with spinal surgery. Daily PA was measured throughout 4 consecutive days using four tri-axial accelerometers and patient-reported functional status was reported using the SRS-22 questionnaire. The participants were assessed both before the treatment and after treatment at a 12-month follow-up. Patients with AIS had no significant change in their PA levels at the 12-month follow-up after surgical correction. On the contrary, patients with AIS following a year-long bracing treatment had significantly reduced time spent active ( P = 0.04) with an average reduction in walking steps by 2137 steps/day ( P = 0.005). There was no significant difference in function, pain, self-image and mental health domains following both treatments, as reported by the SRS-22. There was a significant improvement in satisfaction for both treatment groups ( P ≤ 0.02). Significantly reduced PA and increased sedentary time are reported in patients with AIS following bracing treatment. An objective PA assessment is recommended to track the effect of scoliosis treatment on PA. Patients with AIS should be actively encouraged to achieve and maintain their recommended daily PA levels irrespective of the type of treatment. Level of evidence: Level II.

Human Exposure to Hand-Arm Vibration from a Surgical Drill During Simulated Spine Surgery.

OBJECTIVE: During spine surgery, surgeons are exposed to vibrations from surgical drills. Increased exposure to vibration can result in neurologic, vascular, and musculoskeletal impairments. To reduce these risks, occupational health standards have been implemented to limit exposure levels. The purpose of this study was to quantify human exposure to hand-arm vibration from a surgical drill during a simulation of a common spine procedure. METHODS: Vibration measurements were collected during three 30-second surgical trials on a fresh frozen cadaver torso specimen using a standard surgical drill. The daily vibration exposure A(8) was evaluated on the basis of International Organization for Standardization 5349-1, and the occupational health standards, exposure action value, and exposure limit value were calculated. RESULTS: On the basis of vibration exposure, surgeons in this study reached their exposure limits in 8 minutes to monitor tool usage and 32 minutes to terminate equipment usage. CONCLUSIONS: The results demonstrate that a common surgical drill transmits hand-arm vibration levels approaching the exposure action value and exposure limit value over short periods of use. Further investigation is needed to determine the total vibration exposure over an entire workday, specifically in surgeons who perform multiple surgeries within a single day.

Procedures for obtaining muscle physiology parameters during a gracilis free-functioning muscle transfer in adult patients with brachial plexus injury.

A complete understanding of muscle mechanics allows for the creation of models that closely mimic human muscle function so they can be used to study human locomotion and evaluate surgical intervention. This includes knowledge of muscle-tendon parameters required for accurate prediction of muscle forces. However, few studies report experimental data obtained directly from whole human muscle due to the invasive nature of these experiments. This article presents an intraoperative, in vivo measurement protocol for whole muscle-tendon parameters that include muscle-tendon unit length, sarcomere length, passive tension, and active tension in response to external stimulation. The advantage of this protocol is the ability to obtain these rare experimental data in situ in addition to muscle volume and weight since the gracilis is also completely removed from the leg. The entire protocol including the surgical steps for gracilis harvest takes ~ 3 h. Actual testing of the gracilis where experimental data is measured takes place within a 30-min window during surgery.

Upper extremity function in the free living environment of adults with traumatic brachial plexus injuries.

Transition of data acquisition out of the laboratory, into the real world offers a previously inaccessible perspective of physical function. This proves to be beneficial when assessing surgical intervention, especially after a traumatic brachial plexus injury (BPI) causing loss of motor function in an upper extremity (UE). Moving towards the use of real world data in clinical practice as an outcome measure, this study developed a method to report bilateral UE activity in patients with BPI. Three groups of ten subjects each participated in this study-healthy controls, subjects with traumatic BPI prior to surgical treatment (pre-), and subjects who had surgical reconstruction to treat BPI (post-). Subjects wore four activity monitors on bilateral forearms and upper arms for four days. Tri-axial acceleration data were used to calculate asymmetry indices for forearm and upper arm usage. Analysis revealed a bimodal distribution in the post- group, prompting division of this group into two subgroups based on injury type: pan-plexus and upper trunk. While median asymmetry indices at the forearm and upper arm were decreased in the post- group when compared to the pre- group, these differences were not significant. Compared to controls, the pre-surgery group (p < 0.0001, p < 0.0001) and post-surgery group with pan-plexus injuries (p = 0.0074, p = 0.0242) both exhibited statistically significant differences in forearm and upper arm asymmetry, respectively. Further investigation to establish clinically significant differences in asymmetry index is warranted. Importantly, analyzing the activity of UEs following treatment of a BPI provides objective real world evidence of function.

Skeletal muscle mitochondrial dysfunction and muscle and whole body functional deficits in cancer patients with weight loss.

Reductions in skeletal muscle mass and function are often reported in patients with cancer-associated weight loss and are associated with reduced quality of life, impaired treatment tolerance, and increased mortality. Although cellular changes, including altered mitochondrial function, have been reported in animals, such changes have been incompletely characterized in humans with cancer. Whole body and skeletal muscle physical function, skeletal muscle mitochondrial function, and whole body protein turnover were assessed in eight patients with cancer-associated weight loss (10.1 ± 4.2% body weight over 6-12 mo) and 19 age-, sex-, and body mass index (BMI)-matched healthy controls to characterize skeletal muscle changes at the whole body, muscle, and cellular level. Potential pathways involved in cancer-induced alterations in metabolism and mitochondrial function were explored by interrogating skeletal muscle and plasma metabolomes. Despite similar lean mass compared with control participants, patients with cancer exhibited reduced habitual physical activity (57% fewer daily steps), cardiorespiratory fitness [22% lower V̇o2peak (mL/kg/min)] and leg strength (35% lower isokinetic knee extensor strength), and greater leg neuromuscular fatigue (36% greater decline in knee extensor torque). Concomitant with these functional declines, patients with cancer had lower mitochondrial oxidative capacity [25% lower State 3 O2 flux (pmol/s/mg tissue)] and ATP production [23% lower State 3 ATP production (pmol/s/mg tissue)] and alterations in phospholipid metabolite profiles indicative of mitochondrial abnormalities. Whole body protein turnover was unchanged. These findings demonstrate mitochondrial abnormalities concomitant with whole body and skeletal muscle functional derangements associated with human cancer, supporting future work studying the role of mitochondria in the muscle deficits associated with cancer.NEW & NOTEWORTHY To our knowledge, this is the first study to suggest that skeletal muscle mitochondrial deficits are associated with cancer-associated weight loss in humans. Mitochondrial deficits were concurrent with reductions in whole body and skeletal muscle functional capacity. Whether mitochondrial deficits are causal or secondary to cancer-associated weight loss and functional deficits remains to be determined, but this study supports further exploration of mitochondria as a driver of cancer-associated losses in muscle mass and function.

In vivo human gracilis whole-muscle passive stress-sarcomere strain relationship.

We measured the passive mechanical properties of intact, living human gracilis muscles (n=11 individuals, 10 male and 1 female, age: 33±12 years, mass: 89±23 kg, height: 177±8 cm). Measurements were performed in patients undergoing surgery for free-functioning myocutaneous tissue transfer of the gracilis muscle to restore elbow flexion after brachial plexus injury. Whole-muscle force of the gracilis tendon was measured in four joint configurations (JC1-JC4) with a buckle force transducer placed at the distal tendon. Sarcomere length was also measured by biopsy from the proximal gracilis muscle. After the muscle was removed, a three-dimensional volumetric reconstruction of the muscle was created via photogrammetry. Muscle length from JC1 to JC4 increased by 3.3±1.0, 7.7±1.2, 10.5±1.3 and 13.4±1.2 cm, respectively, corresponding to 15%, 34%, 46% and 59% muscle fiber strain, respectively. Muscle volume and an average optimal fiber length of 23.1±0.7 cm yielded an average muscle physiological cross-sectional area of 6.8±0.7 cm2 which is approximately 3 times that measured previously from cadaveric specimens. Absolute passive tension increased from 0.90±0.21 N in JC1 to 16.50±2.64 N in JC4. As expected, sarcomere length also increased from 3.24±0.08 µm at JC1 to 3.63±0.07 µm at JC4, which are on the descending limb of the human sarcomere length-tension curve. Peak passive muscle stress was 27.8±5.5 kPa in JC4 and muscle modulus ranged from 44.8 MPa in JC1 to 125.7 MPa in JC4. Comparison with other mammalian species indicates that human muscle passive mechanical properties are more similar to rodent muscle than to rabbit muscle. These data provide direct measurements of whole-human muscle passive mechanical properties that can be used in modeling studies and for understanding comparative passive mechanical properties among mammalian muscles.

Effects of Selective Dorsal Rhizotomy on Ankle Joint Function in Patients With Cerebral Palsy.

Selective dorsal rhizotomy (SDR) is a neurosurgical technique performed to reduce muscle spasticity and improve motor functions in children with cerebral palsy (CP). In long term, muscle contractures were observed even after SDR. To better understand what is contributing to contracture formation, it is necessary to assess the effects of SDR on joint stiffness. We hypothesized that ankle passive range of motion (ROM) increases and the quasi-stiffness of the ankle joint decreases after SDR in children with CP. This retrospective study included 10 children with diplegic CP (median age 6 years 2 months) who had undergone SDR and for whom gait analysis data were collected 3 months before (Pre-SDR) and 13 months after (Post-SDR) surgery. Additional to clinical measures, ankle quasi-stiffness (the slope of the ankle moment vs. ankle angle plot) was analyzed from gait data. Passive ankle ROM at 0° (p < 0.0001) and 90° knee angles (p < 0.0001) increased after SDR. Dynamic EMG analysis showed improved phasic gastrocnemius activity (p < 0.0001). Equinus gait was improved with the reduction of peak plantar flexion (p < 0.0001), as well as an increase in peak dorsiflexion (p = 0.006) during walking was observed. Ankle joint quasi-stiffness (Pre- and post-SDR median = 0.056 Nm/kg/° and 0.051 Nm/kg/°, and interquartile range: 0.031 Nm/kg/° and 0.019 Nm/kg/°, respectively) decreased significantly (p = 0.0017) after SDR. Moreover, even though the total time of the gait cycle did not change (p = 0.99), the time interval from maximum dorsiflexion to maximum plantar flexion (Pre- and post-SDR median = 0.125 s and 0.156 s, and interquartile range: 0.153 and 0.253 s, respectively) increased significantly (p = 0.0068) after SDR. In conclusion, the decreased ankle quasi-stiffness and the enhanced time interval in the gait cycle due to SDR indicate better motor control and joint stability. Our findings suggest that the long-term contracture formation occurring even after surgical interventions may be related to the stiffening of non-contractile structures.

Low Back Pain in Adults With Transfemoral Amputation: A Retrospective Population-Based Study.

BACKGROUND: Low back pain (LBP) is common among individuals with transfemoral amputation (TFA) and has a negative impact on quality of life. Little is known about health care utilization for LBP in this population and whether utilization varies by amputation etiology. OBJECTIVE: To determine if individuals with TFA have an increased likelihood of seeking care or reporting symptoms of acute or chronic LBP during physician visits after amputation compared with matched individuals without amputation. DESIGN: Retrospective cohort. SETTING: Olmsted County, Minnesota (2010 population: 144 248). PARTICIPANTS: All individuals with incident TFA (N = 96), knee disarticulation, and transfemoral amputation residing in Olmsted County between 1987 and 2014. Each was matched (1:10 ratio) with non-TFA adults on age, sex, and duration of residency. Individuals were divided by etiology of amputation: dysvascular and trauma/cancer. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASUREMENTS: Death and presentation for evaluation of LBP (LBP event) while residing in Olmsted County. LBP events were identified using validated International Classification of Diseases, Ninth Revision (ICD-9) codes and corresponding Berkson, Hospital International Classification of Diseases Adapted (HICDA), and ICD-10 diagnostic codes. Hurdle and competing-risk Cox proportional hazard models were used. RESULTS: Having a TFA of either etiology did appear to correlate with increased frequency of LBP events, although this association was only statistically significant within the dysvascular TFA cohort (dysvascular TFA cohort: relative risk [RR] 1.80, 95% confidence interval [CI] 1.07-3.03, median follow-up 0.78 years; trauma/cancer TFA cohort: RR 1.14, 95% CI 0.58-2.22, median follow-up 7.95 years). In time to event analysis, dysvascular TFA had an increased risk of death and event. Obesity did not significantly correlate with increased frequency of LBP events or time to event for either cohort. At any given point in time, individuals with TFA of either etiology who had phantom limb pain were 90% more likely to have an LBP event (hazard ratio [HR] 1.91, 95% CI 1.11-3.31). Conditional on not dying and no LBP event within the first 2.5 years, individuals with prosthesis had a decreased risk of LBP events in subsequent years. CONCLUSIONS: Risk of LBP events appears to vary by TFA etiology. Obesity did not correlate significantly with increased frequency of LBP event or time to event. Phantom limb pain correlated with decreased time to LBP event after amputation. The association between prosthesis receipt and LBP events is ambiguous. LEVEL OF EVIDENCE: III.

Assessment of Upper Extremity Function.

Assessment of upper extremity function either before or after surgical treatment has been a rapidly evolving field. A reproducible, accurate, and valid assessment tool provides the ability to compare surgical interventions, evaluate physical therapy regimens, and assess novel assistive and restorative technologies. The purpose of this article is to detail the various upper extremity assessment tools and introduce the concept of real-world data acquisition of upper extremity function.

The risk of major cardiovascular events for adults with transfemoral amputation.

BACKGROUND: It is well-known that the risk of cardiac disease is increased for those with lower-limb amputations, likely as a result of the etiology of the amputation. Using a longitudinal population-based dataset, we examined the association between transfemoral amputation (TFA) status and the risk of experiencing a major cardiac event for those undergoing either dysvascular or traumatic amputations. The association of receiving a prosthesis with the risk of experiencing a major cardiac event was also examined. METHODS: Study Population: All individuals with TFA (N 162), i.e. knee disarticulation and transfemoral amputation, residing in Olmsted County, MN, between 1987 and 2014. Each was matched (1:10 ratio) with non-TFA adults on age, sex, and duration of residency. DATA ANALYSIS: A competing risk Cox proportional hazard model was used to estimate the relative likelihood of an individual with a TFA experiencing a major cardiac event in a given time period as compared to the matched controls. The cohort was divided by amputation etiology: dysvascular vs trauma/cancer. Additional analysis was performed by combining all individuals with a TFA to look at the relationship between prosthesis receipt and major cardiac events. RESULTS: Individuals with a dysvascular TFA had an approximately four-fold increased risk of a cardiac event after undergoing an amputation (HR 3.78, 95%CI: 3.07-4.49). These individuals also had an increased risk for non-cardiac mortality (HR 6.27, 95%CI: 6.11-6.58). The risk of a cardiac event was no higher for those with a trauma/cancer TFA relative to the able-bodied controls (HR 1.30, 95%CI: 0.30-5.85). Finally, there was no difference in risk of experiencing a cardiac event for those with or without prosthesis (HR 1.20, 95%CI: 0.55-2.62). CONCLUSION: The high risk of initial mortality stemming from an amputation event may preclude many amputees from cardiovascular disease progression. Amputation etiology is also an important factor: cardiac events appear to be more likely among patients with a dysvascular TFA. Providing a prosthesis does not appear to be associated with a reduced risk of a major cardiac event following amputation.

Patient-Reported and Objectively Measured Function Before and After Reverse Shoulder Arthroplasty.

BACKGROUND AND PURPOSE: Documenting functional outcomes after reverse shoulder arthroplasty (RSA) is critical to advancing patient care. The interplay been self-reported and objectively measured outcome measures has not been widely described. The utilization of wearable devices to document upper extremity limb activity is a new approach for objectively measuring outcomes. Therefore, the purpose of this study was to evaluate changes in pain, and self-reported function and objectively measured limb activity after RSA. We also assessed the influence of pain on self-reported function and objectively measured limb activity to determine the impact of pain on outcomes after RSA. MATERIALS: This study implemented a prospective, repeated-measures design. Fourteen patients undergoing RSA underwent testing before surgery, and 2 and 12 months after surgery. Patient-reported instruments included pain, Disabilities of Arm, Shoulder and hands (DASH), and physical component summary (PCS) of the 36-Item Short Form Health Survey. Objective limb activity (mean activity value, m/s/min epoch; inactive time, %; low activity, %; and high activity, %) was captured with triaxial accelerometers worn on the upper and lower arm. A repeated-measures ANOVA tested for differences across time. The Spearman rank-order correlation was calculated to evaluate the influence of pain on DASH, PCS scores, and mean limb activity. RESULTS: Patient-reported measures improved after surgery (pain, P < .01; DASH, P < .01; PCS, P = .01). No change in limb activity was found at 1 year compared with preoperative values for mean (forearm, P = 1.00; arm, P = .36), inactivity (forearm, P = .33; arm, P = .22), low (forearm, P = .77; arm, P = .11) or high (forearm, P = 1.00; arm, P = .20) activity. There was a relationship between pain and DASH scores 1 year after surgery (P = .04) but not before surgery (P = .16), or 2 months after surgery (P = .30). There was no relationship between pain and PCS scores at any time point (preoperative, P = .97; 2 months, P = .21; 1 year, P = .08) nor pain and limb activity (forearm: preoperative, P = .36; 2 months, P = .67; 1 year, P = .16; arm: preoperative, P = .97; 2 months, P = .59; 1 year, P = .51). CONCLUSIONS: RSA reduced pain and enhanced patient-perceived function. Objectively measured upper extremity limb activity is not different 1 year after surgery compared with preoperative levels. LEVEL OF EVIDENCE: III.

Stereoradiography imaging motion artifact: does it affect radiographic measures after spinal instrumentation?

PURPOSE: Stereoradiography imaging (SRI) is an accurate and reliable low-dose radiographic method. However, patients must remain motionless during image acquisition. Motion artifacts are frequently noted. The aims of the study were to determine the incidence of the SRI motion artifact and assess if motion during SRI acquisition affects radiographic measurements. METHODS: In this retrospective study, 198 patients with spinal instrumentation had biplanar SRI radiographs performed, of whom 39 had concomitant conventional radiographs. Eight coronal and sagittal spinal parameters were independently measured on SRI and conventional radiographs for the 39 patients by 2 observers. Inclusion criteria were: presence of spinal instrumentation of more than six levels and an SRI motion artifact identified on the coronal and/or the sagittal views on either the spinal rods or on the limbs. Means were compared between both types of radiographs using the Student's t test; intraclass correlation coefficients (ICCs) were used for intraobserver reproducibility and interrater reliability. RESULTS: A motion artifact was identified in 19.7 % (n = 39, mean age 19.5 ± 1.7 years) of the cases. There were no differences in any of the coronal or sagittal plane measurements between SRI and X-rays. Intraobserver reliability and interrater reproducibility was high (range 0.81-0.98). CONCLUSIONS: Motion artifact during full-spine stereoradiography imaging acquisition is frequent, but does not affect spinal measurements. SRI with a motion artifact can be used to produce reliable measurements of the sagittal and coronal parameters. Some SRI images with a motion artifact may suggest loss of fixation or bending of the rods. However, after becoming familiar with the appearance of the motion artifact, repeat radiographs are rarely indicated. IRB NUMBER: 14-004872. LEVEL OF EVIDENCE: Level IV.

Kinematic and ergonomic assessment of laparoendoscopic single-site surgical instruments during simulator training tasks.

While laparoendoscopic single-site surgery (LESS) appears to be feasible and safe, instrument triangulation, tissue handling, and other bimanual tasks are difficult even for experienced surgeons. Novel technologies emerged to overcome LESS' procedural and ergonomic difficulties of "tunnel vision" and "instrument clashing." Surgeon kinematics, self-reported workload and upper body discomfort were used to compare straight, bent and two articulating instruments while performing two basic surgical tasks in a LESS simulator. All instruments resulted in bilateral elevation and rotation of the shoulders, excessive forearm motion and flexion and ulnar deviation of wrists. Surgeons' adopted non-neutral upper extremity postures and performed excessive joint excursions to compensate for reduced freedom of movement at the single insertion site and to operate the instrument mechanisms. LESS' cosmetic benefits continue to impact laparoscopic surgery and by enabling performance through improved instruments, ergonomic improvement for LESS can reduce negative impact on surgeon well-being and patient safety.

Evaluate muscle tension using intramuscular pressure device in rabbit tibialis anterior model for improved tendon transfer surgery.

Quantitative evaluation of passive tension in a muscle is important in tendon transfer surgeries, however, currently appropriate intraoperative measurement techniques are lacking. OBJECTIVE: Intramuscular pressure (IMP) is explored as an application to access force. APPROACH: The tibialis anterior (TA) in New Zealand white rabbits (n = 9) was used to test the hypothesis of a strong correlation between the IMP, muscle force, and length. This study also helped to develop intraoperative techniques for future human studies evaluating various insertion techniques (parallel versus perpendicular). MAIN RESULTS: The Pearson correlation between IMP and force for all trials was 0.74 ± 0.30. Separating out the parallel insertion from the perpendicular insertion revealed a significantly higher correlation for parallel, 0.91 ± 0.13 versus 0.56 ± 0.32. SIGNIFICANCE: These data indicate IMP sensors can be used to assess force in a single muscle and the parallel insertion method should be used. New findings • What is the central question of this study? Successful outcomes of tendon and muscle transfers depend on proper muscle tension. A near linear relationship has been seen between muscle force and intramuscular pressure. This study aims to develop an intraoperative technique for assessing passive muscle tension using intramuscular pressure. • What is the main finding and its importance? The findings from this study reveal a high correlation between pressure and passive tension in a single muscle. The techniques developed in this study will allow the translation to a human model. The work will help to improve surgical outcomes and aim to retain muscle strength in the patient following procedures such as tendon and muscle transfers.

Validation of Inertial Measurement Units for Upper Body Kinematics.

The purpose of this study was to validate a commercially available inertial measurement unit (IMU) system against a standard lab-based motion capture system for the measurement of shoulder elevation, elbow flexion, trunk flexion/extension, and neck flexion/extension kinematics. The validation analyses were applied to 6 surgical faculty members performing a standard, simulated surgical training task that mimics minimally invasive surgery. Three-dimensional joint kinematics were simultaneously recorded by an optical motion capture system and an IMU system with 6 sensors placed on the head, chest, and bilateral upper and lower arms. The sensor-to-segment axes alignment was accomplished manually. The IMU neck and trunk IMU flexion/extension angles were accurate to within 2.9 ± 0.9 degrees and 1.6 ± 1.1°, respectively. The IMU shoulder elevation measure was accurate to within 6.8 ± 2.7° and the elbow flexion measure was accurate to within 8.2 ± 2.8°. In the Bland-Altman analyses, there were no significant systematic errors present; however, there was a significant inversely proportional error across all joints. As the gold standard measurement increased, the IMU underestimated the magnitude of the joint angle. This study reports acceptable accuracy of a commercially available IMU system; however, results should be interpreted as protocol specific.