Surgeon Energy Expenditure and Substrate Utilization During Simulated Spine Surgery.

INTRODUCTION: Orthopaedic surgery can be a physically demanding occupation with high rates of fatigue and burnout. Fatigue has been shown to affect surgeon performance with higher rates of errors in fatigued surgeons. The metabolic cost of performing surgery has yet to be quantified. A better understanding of these costs may provide insights into surgeon fatigue and its effect on patient safety. METHODS: Eight subjects performed a one-level lumbar laminectomy and fusion on cadavers. Oxygen consumption (VO2) was measured via indirect calorimetry and used to calculate energy expenditure (EE). Substrate utilization was estimated from measurements of inspired and expired gases (ie, O2 and CO2, respectively). EE was also measured with the use of triaxial accelerometers. RESULTS: The peak VO2 was 11.3 ± 0.4 mL/kg/min. The EEtotal was 132 ± 6 kcal corresponding to the EEtotal/hr of 142 ± 7 kcal/hr. Upper arm accelerometers (154.8 ± 9.8 kcal; r = 0.54) accurately estimated total EE. Subjects used, on average, 53% ± 4% CHO versus 47% ± 7% fat, with peak utilization of 65% ± 5% CHO versus 35% ± 15% fat. DISCUSSION: Simulated orthopaedic spine surgery elicited modest but significant increases in EE over resting. Surgeons used a higher percentage of carbohydrate than would be expected for the intensity of the activity.

Cartilage Metabolism is Modulated by Synovial Fluid Through Metalloproteinase Activity.

Synovial fluid (SF) contains various cytokines that regulate chondrocyte metabolism and is dynamically associated with joint disease. The objective of this study was to investigate the effects of diluted normal SF on catabolic metabolism of articular cartilage under inflammatory conditions. For this purpose, SF was isolated from healthy bovine joints, diluted, and added to cartilage explant cultures stimulated with interleukin-1 (IL-1) for 12 days. The kinetic release of sulfated glycosaminoglycan (sGAG) and collagen, as well as nitric oxide and gelatinase matrix metalloproteinases were analyzed in the supernatant. Chondrocyte survival and matrix integrity in the explants were evaluated with Live/Dead and histological staining. Diluted synovial fluid treatment suppressed sGAG and collagen release, downregulated the production of nitric oxide and matrix metalloproteinases, reduced IL-1-induced chondrocyte death, and rescued matrix depletion. Our results demonstrate that normal SF can counteract inflammation-driven cartilage catabolism. This study reports on the protective function of healthy SF and the therapeutic potential of recapitulation of SF for cartilage repair.

Liver transplantation with a strongly positive crossmatch: case study and literature review.

A positive crossmatch has been associated with increased risk in liver transplantation. To study the clinical significance of preformed donor-specific human leukocyte antigen antibodies (DSAs) in liver transplantation, we reviewed patients who underwent liver transplantation with a strongly positive flow cytometry crossmatch. DSAs were evaluated with a Luminex solid phase assay. The complement-fixing ability of DSAs was tested with a complement component 1q (C1q) assay. Using an assay correlation between complement-dependent cytotoxicity crossmatch, flow cytometry crossmatch, and DSA results, we reviewed the effects of DSAs on the outcomes of our patients as well as reported cases in the literature. Five of 69 liver recipients had a strongly positive crossmatch: 4 had a positive T cell crossmatch [median channel shift (MCS) = 383.5 ± 38.9], and 5 had a positive B cell crossmatch (MCS = 408.8 ± 52.3). The DSAs were class I only in 1 patient, class I and II in 3 patients, and class II only in 1 patient. Cholestasis, acute rejection, or both were observed in 3 of the 4 patients with a positive T cell crossmatch with an MCS approximately greater than 300. The C1q assay was positive for 3 patients. Two had either persistent cholestasis or early acute rejection. One patient who was treated with preemptive intravenous immunoglobulin had an unremarkable outcome despite a positive C1q result. One of the 2 patients with a negative C1q assay experienced persistent cholestasis and early and recurrent acute rejection; the other had an unremarkable outcome. None of the patients died or lost a graft within the first year of transplantation. Our study suggests that human leukocyte antigen antibody screening, flow cytometry crossmatch MCS levels, DSA mean fluorescent intensity levels, and C1q assays may be useful in assessing the risk of antibody-mediated rejection and timely interventions in liver transplantation.

Total knee arthroplasty in patients with a left ventricular assist device.

Many patients with severe cardiac disease can now live for a prolonged period with left ventricular assist devices (LVADs), and some patients will develop noncardiac medical issues that may benefit from surgical intervention. Previous studies have reported a low rate of complications in patients with LVADs undergoing noncardiac surgical procedures. We report the cases of 2 patients with LVADs who underwent total knee arthroplasties for osteoarthritis. Both patients had significant pain relief and improved function; however, management of anticoagulation and bleeding complications was challenging.

Outcomes of total hip and knee arthroplasty after cardiac transplantation.

The outcomes of 18 primary or revision total hip (THA) and knee arthroplasties (TKA) in 9 patients with cardiac transplants were reviewed. Primary total joint arthroplasties were performed for osteonecrosis (5 hips) or osteoarthritis (5 hips, 4 knees). There were no infections in any of these patients. Final Harris Hip Scores were 71.8 for patients with osteonecrosis and 88.6 for osteoarthritis. Eight of 10 hips were pain-free at final follow-up. Two of the 10 primary THAs required late revision at 7 and 10 years after the index arthroplasty. One patient (2 hips and 1 knee) had chronic bilateral lower extremity pain. Total knee arthroplasty range of motion averaged from 7.5° to 118°. Average final Knee Society function score was 79, and objective score was 88. One of 4 patients with primary TKA required a manipulation under anesthesia. No reoperations were required in this group. Overall, patients with heart transplantations on immunosuppression had generally good pain relief after THA and TKA. There were no infections in this small cohort; however, there were many complications.