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OBJECTIVE: To investigate the feasibility of quantitative 3D ultrashort echo time (UTE)-based biomarkers in detecting proteoglycan (PG) loss and collagen degradation in human cartilage. METHODS: A total of 104 cartilage samples were harvested for a trypsin digestion study (n=44), and a sequential trypsin and collagenase digestion study (n=60), respectively. 44 cartilage samples were randomly divided into a trypsin digestion group (tryp group) and a control group (PBS group) (n=22 for each group) for the trypsin digestion experiment. The remaining 60 cartilage samples were equally divided into four groups (n=15 for each group) for sequential trypsin and collagenase digestion, including PBS+Tris (incubated in PBS, then Tris buffer solution), PBS+30U col (incubated in PBS, then 30U/ml collagenase (30U col) with Tris buffer solution), tryp+30U col (incubated in trypsin solution, then 30U/ml collagenase with Tris buffer solution), and tryp+Tris (incubated in trypsin solution, then Tris buffer solution). The 3D UTE-based MRI biomarkers included T(1), multi-echo T(2)*, adiabatic T(1ρ) (AdiabT(1ρ)), magnetization transfer ratio (MTR), and modeling of macromolecular proton fraction (MMF). For each cartilage sample, UTE-based biomarkers (T(1), T(2)*, AdiabT(1ρ), MTR, and MMF) and sample weight were evaluated before and after treatment. PG and hydroxyproline assays were performed. Differences between groups and correlations were assessed. RESULTS: All evaluated biomarkers were able to differentiate between healthy and degenerated cartilage in the trypsin digestion experiment, but only T(1) and AdiabT(1ρ) were significantly correlated with the PG concentration in the digestion solution (p=0.004 and 0.0001, respectively). In the sequential digestion experiment, no significant differences were found for T(1) and AdiabT(1ρ) values between PBS+Tris and PBS+30U col groups (p=0.627 and 0.877, respectively), but T(1) and AdiabT(1ρ) values increased significantly in the tryp+Tris (p=0.031 and 0.024, respectively) and tryp+30U col groups (both p

Background: Previously, we have demonstrated that extending a continuous femoral nerve block (cFNB) from overnight to 4 days after total knee arthroplasty (TKA) provides clear benefits during the infusion, but not subsequent to catheter removal. However, there were major limitations in generalizing the results of that investigation, and we subsequently performed a very similar study using a multicenter format, with many health care providers, in patients on general orthopedic wards, thus greatly improving inference of the results to the general population. Not surprisingly, the perioperative/short-term outcomes differed greatly from the first, more limited study. We now present a prospective follow-up study of the previously published, multicenter, randomized controlled clinical trial to investigate the possibility that an extended ambulatory cFNB decreases long-term pain, stiffness, and functional disability after TKA, which greatly improves inference of the results to the general population. Methods: Subjects undergoing TKA received a cFNB with ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to continue either perineural ropivacaine (n = 28) or normal saline (n = 26). Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months after surgery. This index evaluates pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of 4 of the 6 time points, including day 7 and at least 2 of months 3, 6, and 12. Results: The 2 treatment groups had similar Western Ontario and McMaster Universities Osteoarthritis scores for the mean area-under-the-curve calculations (point estimate for the difference in mean area under the curve for the 2 groups [overnight infusion group − extended infusion group] = 3.8; 95% confidence interval, −3.8 to +11.3; P = 0.32) and at all individual time points (P > 0.05). Conclusions: This investigation found no evidence that extending an overnight cFNB to 4 days improves (or worsens) subsequent pain, stiffness, or physical function after TKA in patients of multiple centers convalescing on general orthopedic wards.

Continuous femoral nerve blocks provide potent analgesia and other benefits after knee surgery. Perineural catheter placement techniques using ultrasound guidance and electrical stimulation (ES) have been described, but the optimal method remains undetermined. We tested the hypothesis that ultrasound guidance alone requires less time for femoral perineural catheter insertion and produces equivalent results compared with ES alone.Preoperatively, patients receiving a femoral perineural catheter for knee surgery were randomly assigned to either ultrasound guidance with a nonstimulating catheter or ES with a stimulating catheter. The primary outcome was the catheter placement procedure time (minutes) starting when the ultrasound transducer (ultrasound group) or catheter insertion needle (ES group) first touched the patient and ending when the catheter insertion needle was removed after catheter insertion.Perineural catheters placed with ultrasound guidance (n = 20) took a median (10th-90th percentiles) of 5.0 (3.9-10.0) minutes compared with 8.5 (4.8-30.0) minutes for ES (n = 20; P = .012). All ultrasound-guided catheters were placed according to the protocol (n = 20) versus 85% of ES-guided catheters (n = 20; P = .086). Patients in the ultrasound group had a median procedure-related discomfort score of 0.5 (0.0-3.1) compared with 2.5 (0.0-7.6) for the ES group (P = .015). There were no vascular punctures with ultrasound guidance versus 4 in the ES group (P = .039).Placement of femoral perineural catheters takes less time with ultrasound guidance compared with ES. In addition, ultrasound guidance produces less procedure-related pain and prevents inadvertent vascular puncture.

BACKGROUND: We previously provided evidence that extending an overnight continuous femoral nerve block to 4 days after tricompartment knee arthroplasty (TKA) provides clear benefits during the perineural infusion in the immediate postoperative period. However, it remains unknown if the extended infusion improves subsequent health-related quality of life between 7 days and 12 mo. METHODS: Patients undergoing TKA received a femoral perineural infusion of ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to either continue perineural ropivacaine (n 25) or normal saline (n 25) in a double-masked fashion. Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 mo after surgery. The WOMAC evaluates three dimensions of health-related quality of life: pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of 4 of the 6 time points, including day 7 and at least 2 of mo 3, 6, and 12. RESULTS: The two treatment groups had similar WOMAC scores for the mean area under the curve calculations (point estimate for the difference in mean area under the curve for the two groups [overnight infusion groupextended infusion group] 1.2, 95% confidence interval: 5.6 to 8.0; P0.72) and at all individual time points (P0.05). CONCLUSIONS: We found no evidence that extending an overnight continuous femoral nerve block to 4 days improves (or worsens) subsequent health-related quality of life between 7 days and 12 mo after TKA. (ClinicalTrials.gov number, NCT00135889.) (Anesth Analg 2009;108:1320‐5)

We have shown previously that treadmill exercise within lower body negative pressure (LBNPex) maintains upright exercise capacity (peak oxygen consumption, V̇o2peak) in men after 5, 15, and 30 days of bed rest (BR). We hypothesized that LBNPex protects treadmill V̇o2peak and sprint speed in women during a 30-day BR. Seven sets of female monozygous twins volunteered to participate. Within each twin set, one was randomly assigned to a control group (Con) and performed no countermeasures, and the other was assigned to an exercise group (Ex) and performed a 40-min interval (40–80% pre-BR V̇o2peak) LBNPex (51 ± 5 mmHg) protocol, plus 5 min of static LBNP, 6 days per week. Before and immediately after BR, subjects completed a 30.5-m sprint test and an upright graded treadmill test to volitional fatigue. These results in women were compared with previously reported reductions in V̇o2peak and sprint speed in male twins after BR. In women, sprint speed (−8 ± 2%) and V̇o2peak (−6 ± 2%) were not different after BR in the Ex group. In contrast, both sprint speed (−24 ± 5%) and V̇o2peak (−16 ± 3%) were significantly less after BR in the Con group. The effect of BR on sprint speed and V̇o2peak after BR was not different between women and men. We conclude that treadmill exercise within LBNP protects against BR-induced reductions in V̇o2peak and sprint speed in women and should prove effective during long-duration spaceflight.

Bone mineral density (BMD) is a measure of a person's skeletal mineral content, and assessing BMD by dual x-ray absorptiometry (DEXA) can help to diagnose diseases of low bone density. In this study, we determine the heritability of BMD in male and female monozygotic twin subjects using DEXA in 13 specific anatomical regions. In an attempt to quantify the genetic contribution of gender and skeletal region to BMD heritability, we scanned 14 pairs of identical twins using DEXA and calculated the broad-sense heritability coefficient (H(2)) in each of the 13 different body regions. The region of the body that was most heritable for both genders was the head (H(2) >or= 95%). When males were compared to females, H(2) values for male hip (H(2) = 87%) and lower extremities (H(2) = 90%) were higher than those in females (H(2) = 49% and 56%, respectively). Conversely, H(2) value for the female pelvis (H(2) = 68%) was higher than that for males (H(2) = 26%). These data show that different regions of the skeleton exhibit different degrees of heritability, and that the variation depends on gender.

ANALGESIA for hip arthroplasty is traditionally provided by a multimodal regimen of oral and intravenous analgesics within the United States.1 However, postoperative opioid use is associated with undesirable side effects,2,3 and inadequate analgesia often results which interferes with sleep, general activity, and physical therapy.4 The latter is of particular importance because early mobilization is associated with decreased venous thromboembolism and shorter hospitalization as well as improved quality-of-life outcomes.5-7 An epidural infusion is thus often added to help mitigate these impediments to recovery.1 An alternative analgesic option is a continuous lumbar plexus block (cLPB) via the posterior approach.8 This technique involves the percutaneous insertion of a catheter directly into the ipsilateral psoas muscle in the lower lumbar region.9 The catheter is then infused with local anesthetic, resulting in potent, unilateral analgesia free of systemic side effects. Unlike femoral perineural infusion after total knee arthroplasty, cLPB for hip arthroplasty remains relatively uninvestigated—especially using the posterior approach. For example, data are unavailable from a randomized, masked, controlled trial even quantifying posterior cLPB analgesic potency and opioid sparing after hip arthroplasty. Similarly, any effect of a posterior cLPB on ambulation, hip flexion, sleep disturbances, or discharge readiness after hip arthroplasty remains unexamined and unknown. Previously published investigations involving hip arthroplasty provided posterior cLPB exclusively in hospitalized patients and are limited by one or more methodologic issues such as a retrospective study design; lack of randomization, adequately concealed treatment allocation (“blinding”), or placebo controls10; inadequate or missing sample-size estimates; or failure to specify primary endpoints a priori.11 An advantage of cLPB is that, unlike traditional intravenous opioid administration or epidural infusion, cLPB may be continued after discharge using a portable infusion pump.12 Consequently, ambulatory cLPB offers the potential of providing prolonged analgesia while simultaneously decreasing disability and hospitalization duration after hip arthroplasty and similar procedures. Use of ambulatory cLPB after hip arthroplasty has been reported just once, in a small series of subjects who were discharged home the day after surgery with their perineural infusions continuing for over 4 days.13 However, that investigation did not include a control group, and so the extent to which ambulatory cLPB influenced discharge readiness remains unknown. Therefore, the primary objective of this dual-center, randomized, triple-masked (patients, investigators, and statisticians), placebo-controlled study was to test the hypotheses that, compared with an overnight cLPB, a 4-day ambulatory cLPB increases ambulation distance and shortens the time until three specific, predefined readiness-for-discharge criteria are met after hip arthroplasty. The three discharge-related criteria were (1) adequate analgesia, (2) independence from intravenous opioids, and (3) sufficient ambulation. These criteria were chosen because failure to meet one or more of them accounts for the majority of hospitalization days in hip arthroplasty patients at our institutions. Secondary endpoints included maximum passive hip flexion, average and worst resting and dynamic pain scores, oral and intravenous opioid requirements, sleep disturbances, and patient satisfaction.

Background The authors tested the hypotheses that, compared with an overnight continuous femoral nerve block (cFNB), a 4-day ambulatory cFNB increases ambulation distance and decreases the time until three specific readiness-for-discharge criteria are met after tricompartment total knee arthroplasty. Methods Preoperatively, all patients received a cFNB (n = 50) and perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomly assigned to either continue perineural ropivacaine or switch to perineural normal saline. Primary endpoints included (1) time to attain three discharge criteria (adequate analgesia, independence from intravenous analgesics, and ambulation of at least 30 m) and (2) ambulatory distance in 6 min the afternoon after surgery. Patients were discharged with their cFNB and a portable infusion pump, and catheters were removed on postoperative day 4. Results Patients given 4 days of perineural ropivacaine attained all three discharge criteria in a median (25th-75th percentiles) of 25 (21-47) h, compared with 71 (46-89) h for those of the control group (estimated ratio, 0.47; 95% confidence interval, 0.32-0.67; P Conclusions Compared with an overnight cFNB, a 4-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 53% after tricompartment total knee arthroplasty. However, the extended infusion did not increase ambulation distance the afternoon after surgery. (ClinicalTrials.gov No. NCT00135889.).

Background: Acute compartment syndrome has been an underreported complication during spine surgery with the patient positioned on the so-called 90/90 kneeling frame (with 90° of both hip and knee flexion), presumably because of elevated intramuscular pressures in the dependent leg compartments. The purpose of the present study was to characterize and quantify certain parameters that affect the risk for acute compartment syndrome experimentally and to make objective comparisons with other spine surgery positions. Methods: Eight healthy volunteers were positioned in three spine surgery positions: the 90/90 kneeling position, the so-called 45/45 suspended position (with the hips and knees both flexed to 45° with the legs suspended on a sling), and the prone position. Intramuscular pressures were measured in all four left leg compartments with slit catheters. Local blood pressure and applied load beneath the leg were also measured. Results: The 90/90 kneeling position was associated with significantly increased intramuscular pressure in the anterior compartment (30.8 ± 5.7 mm Hg) in comparison with the prone position (13.5 ± 1.7 mm Hg) and the 45/45 suspended position (13.8 ± 1.7 mm Hg). In the 90/90 kneeling position, these values correlated with subject weight (r = 0.72, p = 0.045) and the applied body weight load measured beneath the leg (r = 0.74, p = 0.037). The mean differences between intramuscular pressure and ankle blood pressure were more pronounced as the position of the ankle dropped below the level of the heart in the 45/45 suspended and the 90/90 kneeling positions. Conclusions: The 90/90 kneeling position results in elevated intramuscular pressure in the anterior compartment of the leg. This elevated pressure correlates also with subject weight. The 90/90 kneeling position may predispose patients to the development of an acute compartment syndrome during prolonged spine surgery, with heavier patients being at increased risk. In certain instances, the surgeon may consider using the 45/45 suspended position to minimize this risk.

Orthopaedic rehabilitation is a unique subspecialty of orthopaedic surgery that incorporates surgeons and allied health professionals from several disciplines and regional subspecialties. The subspecialty deals with problems associated with neuromuscular disorders (stroke, brain injury, cerebral palsy, and ­poliomyelitis), spinal injury and deformity, total joint reconstruction, sports injury, pediatric orthopaedic surgery, hand surgery, and foot and ankle surgery. The diversity of orthopaedic rehabilitation is reflected by the many diverse subspecialists found in the membership of the Orthopaedic Rehabilitation Association (ORA). Because of the diverse nature of this orthopaedic subspecialty, a discussion on advances in orthopaedic ­rehabilitation can be accomplished by coverage or separate discussions of several topics. The following report highlights some of the advancements in orthopaedic rehabilitation within the last year. It reviews several of the topics presented at the most recent Annual Meetings of the ORA as well as topics covered on ORA Specialty Day during the American Academy of Orthopaedic Surgeons (AAOS) Annual Meeting. In addition, recent information from published abstracts and manuscripts pertinent to orthopaedic rehabilitation is included. This information covers diverse topics, such as neuromuscular disorders (stroke and brain injury as well as poliomyelitis), spine surgery (vertebroplasty and kypho­plasty), adult reconstruction (total knee arthroplasty and ­associated rehabilitation), and several aspects of hand re­habilitation after surgery. We conclude the discussion with “What’s New in the Orthopaedic Rehabilitation Association,” including a brief background and an update on the society. ### Stroke and Traumatic Brain Injury Several new operative procedures for the management of patients with acquired spasticity and paralysis have been recently discussed1-3. The shoulder, which has traditionally received r­elatively little attention in patients with stroke or traumatic brain injury, was among the main topics covered at the recent ORA Specialty Day held in San Francisco on March 3, 20011-3. There were discussions on evaluation, management …

Background: Acute compartment syndrome has been widely reported in legs positioned in the lithotomy position for prolonged general surgical, urologic, and gynecologic procedures. The orthopaedic literature also contains reports of this complication in legs positioned on a fracture table in the hemilithotomy position. The purpose of this study was to identify the risk factors for development of acute compartment syndrome resulting from this type of leg positioning. Methods: Eight healthy volunteers were positioned on a fracture table. Intramuscular pressures were continuously measured with a slit catheter in all four compartments of the left leg with the subject supine, in the hemilithotomy position with the calf supported, and in the hemilithotomy position with the heel supported but the calf free. Blood pressure was measured intermittently with use of automated pressure cuffs. Results: Changing from the supine to the calf-supported position significantly increased the intramuscular pressure in the anterior compartment (from 11.6 to 19.4 mm Hg) and in the lateral compartment (from 13.0 to 25.8 mm Hg). Changing from the calf-supported to the heel-supported position significantly decreased intramuscular pressure in the anterior, lateral, and posterior compartments (to 2.8, 3.4, and 1.9 mm Hg, respectively). The mean diastolic blood pressure in the ankle averaged 63.9 mm Hg in the supine position, which significantly decreased to 34.6 mm Hg in the calf-supported position. Changing to the heel-supported position had no significant effect on the diastolic blood pressure in the ankle (mean, 32.8 mm Hg). The mean difference between intramuscular pressure and diastolic blood pressure in the supine position was approximately 50 mm Hg in each of the four compartments. This mean difference significantly decreased to

The objectives of this study were 1) to determine the degree to which soleus motoneurons find their appropriate target following crush and transection injuries to the sciatic nerve, and 2) to determine whether repair of a transected nerve with a silicone tube leads to greater specificity of reinnervation and recovery of muscle function than the standard epineurial suture repair method. Sixty adult female Sprague-Dawley rats were randomly assigned to one of three sciatic nerve injury groups : crush injury, transection with epineurial suture repair, or transection with a silicone tube repair. The degree to which soleus motoneurons were able to find their appropriate target following a sciatic nerve injury was examined using a double labeling dye technique in which the original soleus motor pool was labeled with fast blue and reinnervating motoneurons were labeled with Dil. Soleus motoneurons were able to find their appropriate target following a crush injury. The accuracy of reinnervation following a transection injury and repair, however, was relatively poor. Only 14% of the original soleus motoneurons found the correct target following a transection injury. Repair of a lesioned nerve with a silicone tube and a 5-mm gap as opposed to epineurial sutures did not increase the specificity of reinnervation or the degree of muscle recovery.

Exertional rhabdomyolysis is a condition that is becoming more frequently diagnosed and of increasing importance to orthopedic surgeons. A delay in diagnosis and treatment can lead to serious, even fatal, complications. We report a case of exertional rhabdomyolysis followed by a general discussion of this disorder along with its evaluation and management.

Serum cobalt (Co) and chromium (Cr) levels are commonly used to screen for excessive wear of metal-on-metal hip replacements. However, it is unknown how rapidly these should decline after revision. 25 patients with average Co and Cr ion levels of 56.3 μg/L and 20.5 μg/L were followed with serial ion level testing post-revision. Over the first 6 weeks post-revision, the rate of decline for Co and Cr was approximately 2% per day and this slowed to approximately 1% decline per day over the ensuing 6 weeks. This translated to a decline of approximately 80% from the starting value after 6 weeks and a decline of approximately 90% after 12 weeks post-revision. The rate of decline for both Co and Cr was significantly faster during the first 6 weeks (P0.001). In patients with ultra-high Cr levels20 μg/L, the rate of Cr decline is less predictable and may be protracted leading to persistent elevation above 5 μg/L for one year or more post-revision in some cases.

A continuous femoral nerve block (cFNB) involves the percutaneous insertion of a catheter adjacent to the femoral nerve, followed by a local anesthetic infusion, improving analgesia following total knee arthroplasty (TKA). Portable infusion pumps allow infusion continuation following hospital discharge, raising the possibility of decreasing hospitalization duration. We therefore used a multicenter, randomized, triple-masked, placebo-controlled study design to test the primary hypothesis that a four-day ambulatory cFNB decreases the time until each of three predefined readiness-for-discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation ≥ 30 meters) are met following TKA compared with an overnight inpatient-only cFNB. Preoperatively, all patients received a cFNB with perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomized to either continue perineural ropivacaine (n=39) or switch to normal saline (n=38). Patients were discharged with their cFNB and portable infusion pump as early as postoperative day three. Patients given four days of perineural ropivacaine attained all three criteria in a median (25th–75th percentiles) of 47 (29–69) hours, compared with 62 (45–79) hours for those of the control group (Estimated ratio=0.80, 95% confidence interval: 0.66–1.00; p=0.028). Compared with controls, patients randomized to ropivacaine met the discharge criterion for analgesia in 20 (0–38) vs. 38 (15–64) hours (p=0.009), and intravenous opioid independence in 21 (0–37) vs. 33 (11–50) hours (p=0.061). We conclude that a four-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 20% following TKA compared with an overnight cFNB, primarily by improving analgesia.

We previously reported that extending an overnight continuous posterior lumbar plexus nerve block to 4 days after hip arthroplasty provides clear benefits during the perineural infusion in the immediate postoperative period. However, it remains unknown whether the extended infusion improves subsequent health-related quality of life.Patients undergoing hip arthroplasty received a posterior lumbar plexus perineural infusion of ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to continue either perineural ropivacaine (n = 24) or normal saline (n = 23) in a double-masked fashion. Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative Day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index preoperatively and then at 7 days and 1, 2, 3, 6, and 12 mo after surgery. The WOMAC evaluates three dimensions of health-related quality of life, such as pain, stiffness, and physical functional disability (global score of 0-96, lower scores indicate lower levels of symptoms or physical disability). For inclusion in the primary analysis, we required a minimum of three of the six timepoints, including Day 7 and at least two of Months 3, 6, and 12.The two treatment groups had similar global WOMAC scores for the mean area under the curve calculations (point estimate for the difference in mean area under the curve for the two groups [extended infusion group-overnight infusion group] = 0.8, 95% confidence interval: -5.3 to + 6.8 [-5.5% to + 7.1%]; P = 0.80) and at all individual timepoints (P0.05).This investigation found no evidence that extending an overnight continuous posterior lumbar plexus nerve block to 4 days improves (or worsens) subsequent health-related quality of life between 7 days and 12 mo after hip arthroplasty.

The authors tested the hypotheses that after hip arthroplasty, ambulation distance is increased and the time required to reach three specific readiness-for-discharge criteria is shorter with a 4-day ambulatory continuous lumbar plexus block (cLPB) than with an overnight cLPB.A cLPB consisting of 0.2% ropivacaine was provided from surgery until the following morning. Patients were then randomly assigned either to continue ropivacaine or to be switched to normal saline. Primary endpoints included (1) time to attain three discharge criteria (adequate analgesia, independence from intravenous analgesics, and ambulationor = 30 m) and (2) ambulatory distance in 6 min the afternoon after surgery. Patients were discharged with their cLPB and a portable infusion pump, and catheters were removed on the fourth postoperative day.Patients given 4 days of perineural ropivacaine (n = 24) attained all three discharge criteria in a median (25th-75th percentiles) of 29 (24-45) h, compared with 51 (42-73) h for those of the control group (n = 23; estimated ratio = 0.62; 95% confidence interval, 0.45-0.92; P = 0.011). Patients assigned to receive ropivacaine ambulated a median of 34 (9-55) m the afternoon after surgery, compared with 20 (6-46) m for those receiving normal saline (estimated ratio = 1.3; 95% confidence interval, 0.6-3.0; P = 0.42). Three falls occurred in subjects receiving ropivacaine (13%), versus none in subjects receiving normal saline.Compared with an overnight cLPB, a 4-day ambulatory cLPB decreases the time to reach three predefined discharge criteria by an estimated 38% after hip arthroplasty. However, the extended infusion did not increase ambulation distance to a statistically significant degree.

Introduction: Exercise capacity is reduced after both short- and long-duration exposures to microgravity. Previously, we have documented that supine treadmill exercise within lower-body negative pressure (LBNPex) maintains upright exercise responses in men after 5 and 15 d of bed rest, as a simulation of microgravity. Purpose: The purpose of this study was to determine whether LBNPex would protect against loss of upright exercise capacity (V?O2peak) and sprint performance during a longer-duration bed rest. Methods: Eight sets of male twins participated in 30 d of bed rest. Within each twin pair, one was randomly assigned to a control group (CON) who performed no exercise, and the other was assigned to an exercise group (EX) that performed a 40-min interval (40-80% pre-bed rest V?O2peak) LBNPex (55 ± 4 mm Hg) protocol, plus 5 min of resting LBNP, 6 d·wk-1. LBNP produced footward force equivalent to 1.0-1.2 body weight. Before and after bed rest, subjects completed an upright graded exercise test to volitional fatigue and a sprint test of 30.5 m. Results: After bed rest, V?O2peak was decreased significantly in the CON subjects (-23 ± 4%, P < 0.01) but was maintained in the EX subjects (-3 ± 3%). Sprint time was increased in the CON subjects (24 ± 8%, P < 0.05) but was maintained in the EX group (8 ± 2%). Conclusions: This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long-duration space flight.

The detrimental impact of long duration space flight on physiological systems necessitates the development of exercise countermeasures to protect work capabilities in gravity fields of Earth, Moon and Mars. The respective rates of physiological deconditioning for different organ systems during space flight has been described as a result of data collected during and after missions on the Space Shuttle, International Space Station, Mir, and bed rest studies on Earth. An integrated countermeasure that simulates the body's hydrostatic pressure gradient, provides mechanical stress to the bones and muscles, and stimulates the neurovestibular system may be critical for maintaining health and well being of crew during long-duration space travel, such as a mission to Mars. Here we review the results of our studies to date of an integrated exercise countermeasure for space flight, lower body negative pressure (LBNP) treadmill exercise, and potential benefits of its application to athletic training on Earth. Additionally, we review the benefits of Lower Body Positive Pressure (LBPP) exercise for rehabilitation of postoperative patients. Presented first are preliminary data from a 30-day bed rest study evaluating the efficacy of LBNP exercise as an integrated exercise countermeasure for the deconditioning effects of microgravity. Next, we review upright LBNP exercise as a training modality for athletes by evaluating effects on the cardiovascular system and gait mechanics. Finally, LBPP exercise as a rehabilitation device is examined with reference to gait mechanics and safety in two groups of postoperative patients.

Counteracting bone loss is required for future space exploration. We evaluated the ability of treadmill exercise in a LBNP chamber to counteract bone loss in a 30-day bed rest study. Eight pairs of identical twins were randomly assigned to sedentary control or exercise groups. Exercise within LBNP decreased the bone resorption caused by bed rest and may provide a countermeasure for spaceflight. INTRODUCTION: Bone loss is one of the greatest physiological challenges for extended-duration space missions. The ability of exercise to counteract weightlessness-induced bone loss has been studied extensively, but to date, it has proven ineffective. We evaluated the effectiveness of a combination of two countermeasures-treadmill exercise while inside a lower body negative pressure (LBNP) chamber-on bone loss during a 30-day bed rest study. MATERIALS AND METHODS: Eight pairs of identical twins were randomized into sedentary (SED) or exercise/LBNP (EX/LBNP) groups. Blood and urine samples were collected before, several times during, and after the 30-day bed rest period. These samples were analyzed for markers of bone and calcium metabolism. Repeated measures ANOVA was used to determine statistical significance. Because identical twins were used, both time and group were treated as repeated variables. RESULTS: Markers of bone resorption were increased during bed rest in samples from sedentary subjects, including the collagen cross-links and serum and urinary calcium concentrations. For N-telopeptide and deoxypyridinoline, there were significant (p < 0.05) interactions between group (SED versus EX/LBNP) and phase of the study (sample collection point). Pyridinium cross-links were increased above pre-bed rest levels in both groups, but the EX/LBNP group had a smaller increase than the SED group. Markers of bone formation were unchanged by bed rest in both groups. CONCLUSIONS: These data show that this weight-bearing exercise combined with LBNP ameliorates some of the negative effects of simulated weightlessness on bone metabolism. This protocol may pave the way to counteracting bone loss during spaceflight and may provide valuable information about normal and abnormal bone physiology here on Earth.

Emergent irrigation and debridement has been accepted as a mainstay of open fracture treatment. The purpose of this study was to evaluate the infectious outcome of open tibia fractures relative to the time from injury to operative irrigation and debridement.One hundred seventy-eight patients with 191 consecutive fractures were retrospectively reviewed. Of these, 103 patients with 106 fractures were available for this study, with an average follow-up of 10.23 months.Results revealed 21.7% type I fractures, 43.4% type II fractures, 16.0% type IIIa fractures, 11.3% type IIIb fractures, and 7.5% type IIIc fractures. Of all fracture types, 22.6% became infected and 5.7% went on to have osteomyelitis. The average time to treatment was not significantly different in infected versus noninfected fractures across fracture types. No infection occurred when the time to surgery was within 2 hours; however, no significant increase in infection was discovered with respect to patients treated after 6 hours compared with those treated within 6 hours.The results support the Gustilo grading system of open fractures as a significant prognostic indicator for infectious complication. We continue to support the emergent treatment of open tibia fractures.

Objective: To determine the types and patterns of injuries seen in personal watercraft (PWC) accidents. Design: A retrospective review of medical records and imaging studies. Setting: Level I and 2 trauma centers in San Diego County, California. Patients/Participants: Trauma patients treated for PWC-related injuries between 1984 and 1997. Main Outcome Measurements: Evaluation of injury patterns via chart review and imaging studies. Intervention: None. Results: A total of 62 patients were identified. The average age was 23 years (range 2-59 years). There were 41 males and 21 females. A total of 35 injuries (56%) involved another PWC. Of patients, 24 had loss of consciousness, with 8 closed head injuries. There were 17 chest injuries, with 10 pneumothoraces, and 16 lower extremity fractures (9 femur, 3 hip, 3 tibia-fibula, and I patella). Conclusions: Injuries related to PWC have increased dramatically over the past several years, becoming one of the leading causes of recreational water-sport injuries. This study supports a high level of awareness for significant blunt trauma to the chest and lower extremities in patients involved in PWC accidents.