Tourniquet induced ischemia and changes in metabolism during TKA: a randomized study using microdialysis

Intravenous Cefazolin Achieves Sustained High Interstitial Concentrations in Open Lower Extremity Fractures

BACKGROUND

Infection remains a serious clinical concern in patients with open fractures, despite timely antibiotic administration and surgical debridement. Soft tissue and periosteal stripping may alter local tissue homeostasis and antibiotic pharmacokinetics in the injured limb. The tissue (interstitial) concentration of intravenously administered antibiotics at an open fracture site has not been characterized using direct sampling techniques.

QUESTION/PURPOSE

We performed this study to evaluate the concentration and pharmacokinetics of intravenously delivered cefazolin at an open fracture site after surgical debridement.

METHODS

Twelve patients with an open fracture distal to the knee who presented at a regional Level I trauma center were approached for enrollment in this nonrandomized, observational study. Of the 12 patients, eight adults (one female, seven male) with a median age of 32 years (range 23 to 51 years) were enrolled and underwent successful sample collection for analysis. Three patients had incomplete datasets because of equipment malfunction and one elected not to participate. Seven patients had open tibia fractures, and one patient had an open fibula fracture associated with a closed tibia fracture. There were six Gustilo-Anderson Type II injuries and two Type IIIA injuries. Empiric antibiotics were administered in the prehospital setting or in the emergency department according to institutional protocol. When patients were taken to the operating room, a 2-g intravenous dose of cefazolin was administered. After surgical debridement, fracture stabilization, and wound closure, a microdialysis catheter was placed transdermally into the injury zone (within 5 cm of the fracture site) and a second catheter was placed in the contralateral uninjured (control) limb. Additional doses of cefazolin were administered every 8 hours postoperatively. Baseline and periodic interstitial fluid and whole blood (plasma) samples were collected in the operating room and at prespecified times for 24 hours postoperatively. Free cefazolin in the interstitial fluid and plasma samples were analyzed by ultra-high-performance liquid chromatography using C 18 column separation with quadrupole time-of-flight mass spectrometry detection. Data from the second postoperative dose of cefazolin were used to characterize pharmacokinetic parameters through a noncompartmental analysis using time-concentration curves of free cefazolin and assuming first-order elimination. For pharmacodynamic analyses, the modal cefazolin minimum inhibitory concentration (MIC) of Staphylococcus aureus (1 µg/mL) was used.

RESULTS

With the samples available, no difference was observed in the median free cefazolin exposure over 24 hours ( f area under the curve [AUC] 0→24hrs ) between injured limbs (352 μg∙hr/mL [IQR 284 to 594 μg∙hr/mL]) and uninjured limbs (341 μg∙hr/mL [IQR 263 to 438 μg∙hr/mL]; p = 0.64). The median time to achieve the maximum concentration of free cefazolin ( f T max ) for injured limbs was delayed (2.7 hours [IQR 2.2 to 3.1 hours]) compared with control limbs (1.7 hours [IQR 1.2 to 2.0 hours]; p = 0.046). The time to the maximum concentration for plasma was not different from that of control limbs (p = 0.08). The time the cefazolin concentration was above the modal S. aureus MIC (T > MIC) in the injured and control limbs over 24 hours was 100% (IQR 100% to 100%) and 100% (IQR 97% to 100%), respectively.

CONCLUSION

These preliminary findings suggest that current prophylactic cefazolin dosing regimens result in successful antibiotic delivery to the traumatized limb in moderately severe open fractures. Although cefazolin delivery to open-fracture wound beds was delayed compared with healthy tissues, the cefazolin concentration was sustained above the European Union Committee Antimicrobial Susceptibility Testing modal MIC for S. aureus , demonstrating a high likelihood of a prophylactic antimicrobial environment at an open fracture site with this empiric antimicrobial regimen. Importantly, patients in this analysis had Gustilo-Anderson Types II and IIIA injuries. Further research with a larger patient cohort is needed to determine whether antibiotic delivery to traumatized soft tissues in patients with higher-grade open fractures (Gustilo-Anderson Types IIIB and IIIC) demonstrates similar pharmacokinetic characteristics.

LEVEL OF EVIDENCE

Level II, therapeutic study.

The effect of tourniquet use on postoperative opioid consumption after ankle fracture surgery - a retrospective cohort study

OBJECTIVES

A pneumatic tourniquet is often used during ankle fracture surgery to reduce bleeding and enhance the visibility of the surgical field. Tourniquet use causes both mechanical and ischemic pain. The main purpose of this study was to evaluate the effect of tourniquet time on postoperative opioid consumption after ankle fracture surgery.

METHODS

We retrospectively reviewed the files of 586 adult patients with surgically treated ankle fractures during the years 2014-2016. We evaluated post hoc the effect of tourniquet time on postoperative opioid consumption during the first 24 h after surgery. The patients were divided into quartiles by the tourniquet time (4-43 min; 44-58 min; 59-82 min; and ≥83 min). Multivariable linear regression analysis was used to evaluate the results.

RESULTS

Tourniquets were used in 486 patients. The use of a tourniquet was associated with an increase in the total postoperative opioid consumption by 5.1 mg (95 % CI 1.6-8.5; p=0.004) during the first 24 postoperative hours. The tourniquet time over 83 min was associated with an increase in the mean postoperative oxycodone consumption by 5.4 mg (95 % CI 1.2 to 9.7; p=0.012) compared to patients with tourniquet time of 4-43 min.

CONCLUSIONS

The use of a tourniquet and prolonged tourniquet time were associated with higher postoperative opioid consumption during the 24 h postoperative follow-up after surgical ankle fracture fixation. The need for ethical approval and informed consent was waived by the Institutional Review Board of Northern Ostrobothnia Health District because of the retrospective nature of the study.

Tourniquet use benefits to reduce intraoperative blood loss in patients receiving total knee arthroplasty for osteoarthritis: An updated meta-analysis with trial sequential analysis

PURPOSE

The efficacy and safety of tourniquets use during total knee arthroplasty (TKA) in patients with osteoarthritis remain debated. This updated systematic review and meta-analysis aimed to further evaluate the role of tourniquets use in patients undergoing TKA for knee osteoarthritis by introducing trial sequential analysis.

METHODS

PubMed, Embase, and the Cochrane Library were searched. We used the Cochrane risk of bias tool for quality assessment. Statistical heterogeneity across studies was evaluated using Cochran's Q and I2 statistic. Meta-analysis was performed using Stata/SE 14.0, and trail sequential analysis was performed using TSA software version 0.9.5.10 Beta. In addition, qualitative summary was also used to describe results.

RESULTS

15 randomized controlled trials (RCTs) involving 1202 patients were included in the meta-analysis. The pooled results showed that tourniquet use during TKA significantly reduced intraoperative blood loss (mean difference (MD)= -123.84, 95% confidence interval (CI): -163.37 to -84.32, p < .001)and shortened operation time (MD = -4.71, 95% CI: -7.6 to -1.82, p = .001), but there were no significant differences in postoperative blood loss, calculated blood loss, total blood loss, transfusion rate (p = .939), and deep venous thrombosis (DVT) rate between the tourniquet and no-tourniquet groups. TSA confirmed that the result of operation time was false positive, but the results of other outcomes were conclusive. The results of qualitative summary showed conflicting findings in terms of pain, range of motion (RoM) and swelling ratio between the two groups.

CONCLUSIONS

Tourniquet use in patients receiving TKA for osteoarthritis benefits to reduce intraoperative blood loss but has no effect on postoperative blood loss, calculated blood loss, total blood loss, operation time, transfusion rate, and DVT rate. In addition, it remains unclear the difference between the tourniquet and non-tourniquet groups in terms of pain, RoM and swelling ratio.

Evaluation of the Influence of Short Tourniquet Ischemia on Tissue Oxygen Saturation and Skin Temperature Using Two Portable Imaging Modalities

BACKGROUND

The exact influence of tourniquet ischemia on a treated extremity remains unclear.

METHODS

Twenty patients received an operation on one hand under tourniquet ischemia. Twenty healthy volunteers received 10 min of tourniquet ischemia on one of their arms. Measurements of tissue oxygen saturation using near-infrared reflectance-based imaging and skin temperature of the dorsum of the hand were performed at five different timepoints (t0 was performed just before the application of the tourniquet ischemia, t1 directly after the application of the tourniquet ischemia, t2 before the release of the ischemia, t3 directly after the release of the ischemia, and t4 on the following day).

RESULTS

In both groups, tissue oxygen saturation dropped after the application of the tourniquet ischemia compared to t0 and increased after the release of the tourniquet ischemia. In the patient group, tissue oxygen saturation at t4 was higher compared to t0; in contrast, the level of tissue oxygen saturation in the participant group dropped slightly at t4 compared to t0. The measured skin temperature in the patient group showed an increase during the observation period, while it continuously decreased in the group of healthy participants.

CONCLUSIONS

Short-term ischemia did not appear to permanently restrict perfusion in this study design. The non-invasive imaging modalities used were easy to handle and allowed repetitive measurement.

Comparison of efficacy and safety of different tourniquet applications in total knee arthroplasty: a network meta-analysis of randomized controlled trials

OBJECTIVE

Total knee replacement (TKA) is an effective way to treat teratogenic and disabling knee diseases such as advanced osteoarthritis. Tourniquets are often used in TKA to reduce bleeding and to get a better visualization of the surgical field, while it is related to safety concerns. We did this network meta-analysis to comprehensively compare the efficacy and safety of various tourniquet application strategies.

METHOD

PubMed, Embase, Cochrane Library, CNKI, and WanFang Database were systematically searched from January 1990 to May 2020. A network meta-analysis with a frequentist framework was done to assess the relative efficacy and safety by comparing seven clinical important endpoints.

RESULTS

38 eligible studies that assessed 3007 participants who underwent TKA were included in this network meta-analysis. Tourniquet inflation before osteotomy then deflation after wound closure effectively reduce perioperative bleeding (WMD compared with control group -234.66, 95% CI [-409.19 to -60.13]), while shortening the operation time (WMD -8.98, 95%CI [-14.07 to -3.88]) and reducing postoperative complications, including DVT (OR -0.58, 95%CI [-1.19 to 0.03]) and minor wound complications (OR -1.38, 95%CI [-3.00 to 0.25]). No difference was found in the late postoperative knee pain and function outcomes.

CONCLUSIONS

Using tourniquets during the entire operation can effectively reduce blood loss, but it also can cause many safety problems, including DVTs, wound oozing, delayed healing, and serious wound complications. Tourniquet inflation before osteotomy then deflation after wound closure effectively can reduce perioperative bleeding while shortening the operation time and reducing postoperative complications, so it could be the ideal tourniquet application strategy in TKA.Key messagesThis is the first study that comprehensively compared different tourniquet application strategies to evaluate their impact on postoperative recovery following TKA, and five clinically important endpoints were assessed in this study: perioperative blood loss, operation time, postoperative pain and function, and complications.We conclude that tourniquet inflation before osteotomy then deflation after wound closure could be the ideal tourniquet application strategy in TKA.

Effects of tourniquet inflation on peri- and postoperative cefuroxime concentrations in bone and tissue

Background and purpose - Tourniquet is widely used in orthopedic surgery to reduce intraoperative bleeding and improve visualization. We evaluated the effect of tourniquet application on peri- and postoperative cefuroxime concentrations in subcutaneous tissue, skeletal muscle, calcaneal cancellous bone, and plasma. The primary endpoint was the time for which the free cefuroxime concentration was maintained above the clinical breakpoint minimal inhibitory concentration (T > MIC) for Staphylococcus aureus (4 µg/mL).Patients and methods - 10 patients scheduled for hallux valgus or hallux rigidus surgery were included. Microdialysis catheters were placed for sampling of cefuroxime concentrations bilaterally in subcutaneous tissue, skeletal muscle, and calcaneal cancellous bone. A tourniquet was applied on the thigh of the leg scheduled for surgery (tourniquet duration time [range]: 65 minutes [58-77]). Cefuroxime (1.5 g) was administered intravenously 15 minutes prior to tourniquet inflation, followed by a second dose 6 hours later. Dialysates and venous blood samples were collected for 12 hours.Results - A cefuroxime concentration of 4 µg/mL was reached within 23 minutes in all compartments and patients. For cefuroxime the T > MIC (4 µg/mL) ranged between 4.8 and 5.4 hours across compartments, with similar results for the tourniquet and non-tourniquet leg. Comparable T > MIC and penetration ratios were found for the first and second dosing intervals.Interpretation - Administration of cefuroxime (1.5 g) 15 minutes prior to tourniquet inflation is safe in order to achieve tissue concentrations above 4 µg/mL throughout surgery. A tourniquet application time of approximately 1 hour did not affect the cefuroxime tissue penetration in the following dosing interval.

Time to reconsider the routine use of tourniquets in total knee arthroplasty surgery

Aims

Many surgeons choose to perform total knee arthroplasty (TKA) surgery with the aid of a tourniquet. A tourniquet is a device that fits around the leg and restricts blood flow to the limb. There is a need to understand whether tourniquets are safe, and if they benefit, or harm, patients. The aim of this study was to determine the benefits and harms of tourniquet use in TKA surgery.

Methods

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled trials, and trial registries up to 26 March 2020. We included randomized controlled trials (RCTs), comparing TKA with a tourniquet versus without a tourniquet. Outcomes included: pain, function, serious adverse events (SAEs), blood loss, implant stability, duration of surgery, and length of hospital stay.

Results

We included 41 RCTs with 2,819 participants. SAEs were significantly more common in the tourniquet group (53/901 vs 26/898, tourniquet vs no tourniquet respectively) (risk ratio 1.73 (95% confidence interval (CI) 1.10 to 2.73). The mean pain score on the first postoperative day was 1.25 points higher (95% CI 0.32 to 2.19) in the tourniquet group. Overall blood loss did not differ between groups (mean difference 8.61 ml; 95% CI -83.76 to 100.97). The mean length of hospital stay was 0.34 days longer in the group that had surgery with a tourniquet (95% CI 0.03 to 0.64) and the mean duration of surgery was 3.7 minutes shorter (95% CI -5.53 to -1.87).

Conclusion

TKA with a tourniquet is associated with an increased risk of SAEs, pain, and a marginally longer hospital stay. The only finding in favour of tourniquet use was a shorter time in theatre. The results make it difficult to justify the routine use of a tourniquet in TKA surgery.

Cite this article: Bone Joint J 2021;103-B(5):830–839.

Tourniquet-induced ischemia and reperfusion in subcutaneous tissue, skeletal muscle, and calcaneal cancellous bone

This study aimed to evaluated ischemic metabolites in subcutaneous tissue, skeletal muscle, and calcaneal cancellous bone before, during, and after tourniquet application in a simultaneous paired comparison of tourniquet-exposed and non-tourniquet-exposed legs. Ten patients scheduled for hallux valgus or hallux rigidus surgery were included. Microdialysis catheters were placed to simultaneously and continuously sample the metabolites glucose, lactate, pyruvate, and glycerol bilaterally for 12 h in subcutaneous tissue, skeletal muscle, and calcaneal cancellous bone. A tourniquet was applied on the leg planned for surgery (inflation time: 15 min, mean tourniquet duration time (range): 65 (58;77) min). During tourniquet inflation, a 2- to 3-fold increase of the mean lactate/pyruvate ratio was found for all investigated tissues in the tourniquet-exposed leg compared with the non-tourniquet-exposed leg. The lactate/pyruvate ratio recovery time after tourniquet release was within 30 min for skeletal muscle, 60 min for subcutaneous tissue, and 130 min for calcaneal cancellous bone. Only the tourniquet-exposed skeletal muscles were found to be ischemic during tourniquet inflation, defined by a significant increase of the lactate/pyruvate ratio exceeding the ischemic cutoff level of 25; however, this level decreased below 25 immediately after tourniquet release. The glycerol ratio increased instantly after inflation in the tourniquet-exposed leg in skeletal muscle and subcutaneous tissue, and recovered within 60 (skeletal muscle) and 130 min (subcutaneous tissue) after tourniquet release. These findings suggest that applying tourniquet for approximately 1 h results in limited tissue ischemia and cell damage in subcutaneous tissue, skeletal muscle, and calcaneal cancellous bone.

Tourniquet use in total knee replacement surgery: a feasibility study and pilot randomised controlled trial (SAFE-TKR study)

INTRODUCTION

Tourniquets are routinely used during total knee replacement (TKR) surgery. They could increase the risk of thromboembolic events including cerebral emboli, cognitive decline, pain and other adverse events (AEs). A randomised controlled trial to assess whether tourniquet use might safely be avoided is therefore warranted but it is unclear whether such a trial would be feasible.

METHODS

In a single-site feasibility study and pilot randomised controlled trial, adults having a TKR were randomised to surgery with an inflated tourniquet versus a non-inflated tourniquet. Participants underwent brain MRI preoperatively and within 2 days postoperatively. We assessed cognition using the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and Oxford Cognitive Screen (OCS) and thigh pain using a Visual Analogue Scale at baseline and days 1 and 2, and 1 week postsurgery. AEs related to surgery were recorded up to 12 months.

RESULTS

We randomised 53 participants (27 tourniquet inflated and 26 tourniquet not inflated). Fifty-one participants received care per-protocol (96%) and 48 (91%) were followed up at 12 months. One new ischaemic brain lesion was detected. Of the cognitive tests, MoCA was easy to summarise, sensitive to change with lower ceiling effects compared with OCS and MMSE. There was a trend towards more thigh pain (mean 49.6 SD 30.4 vs 36.2 SD 28 at day 1) and more AEs related to surgery (21 vs 9) in participants with an inflated tourniquet compared with those with a tourniquet not inflated.

CONCLUSION

A full trial is feasible, but using MRI as a primary outcome is unlikely to be appropriate or feasible. Suitable primary outcomes would be cognition measured using MoCA, pain and AEs, all of which warrant investigation in a large multicentre trial.

TRIAL REGISTRATION NUMBER

ISRCTN20873088.

Tourniquet use for knee replacement surgery

BACKGROUND

Many surgeons prefer to perform total knee replacement surgery with the aid of a tourniquet. A tourniquet is an occlusive device that restricts distal blood flow to help create a bloodless field during the procedure. A tourniquet may be associated with increased risk of pain and complications.

OBJECTIVES

To determine the benefits and harms of tourniquet use in knee replacement surgery.

SEARCH METHODS

We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) up to 26 March 2020. We searched clinicaltrials.gov, the World Health Organization trials portal, and several international registries and joint registries up to March 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing knee replacement with use of a tourniquet versus without use of a tourniquet and non-randomised studies with more than 1000 participants. Major outcomes included pain, function, global assessment of success, health-related quality of life, serious adverse events (including venous thromboembolism, infection, re-operation, and mortality), cognitive function, and survival of the implant. Minor outcomes included blood loss, economic outcomes, implant stability, and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors screened abstracts and full texts, extracted data, performed risk of bias assessments, and assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 41 RCTs with 2819 participants. Trials included from 20 to 199 participants. Mean age ranged between 58 and 84 years. More than half of the RCTs had unclear risk of selection bias and unclear risk of performance and detection bias due to absence of blinding of participants and surgeons. Major outcomes Pain: at postoperative day 1, pain (on a scale from zero to 10, with higher scores indicating worse pain) was ranked at 4.56 points after surgery without a tourniquet and at 1.25 points (MD) higher (95% CI 0.32 higher to 2.19 higher) with a tourniquet (8 studies; 577 participants), for an absolute difference of 12.5% higher pain scores (95% CI 3.2% higher to 21.9% higher) and a relative difference of 19% higher pain scores (95% CI 3.4% higher to 49% higher) with a tourniquet. Evidence for these findings was of moderate certainty, downgraded due to risk of bias. Knee replacement with a tourniquet probably led to higher postoperative pain scores at day 1, although this difference may or may not be noticeable to patients (based on a minimal clinically important difference (MCID) of 1.0). Function: at 12 months, tourniquet use probably makes little or no difference to function, based on an MCID of 5.3 for Knee Society Score (KSS) and 5.0 for Oxford Knee Score (OKS). Mean function (on a scale from 0 to 100, with higher scores indicating better outcomes) was 90.03 points after surgery without a tourniquet and was 0.29 points worse (95% CI 1.06 worse to 0.48 better) on a 0 to 100 scale, absolute difference was 0.29% worse (1.06% worse to 0.48% better), with a tourniquet (5 studies; 611 participants). This evidence was downgraded to moderate certainty due to risk of bias. Global assessment of success: low-certainty evidence (downgraded due to bias and imprecision) indicates that tourniquet use may have little or no effect on success. At six months, 47 of 50 (or 940 per 1000) reported overall successful treatment after surgery without a tourniquet and 47 of 50 (or 940 per 1000) with a tourniquet (risk ratio (RR) 1.0, 95% CI 0.91 to 1.10) based on one study with 100 participants. Health-related quality of life: at six months, tourniquet may have little or no effect on quality of life. The 12-Item Short Form Survey (SF-12) score (mental component from zero to 100 (100 is best)) was 54.64 after surgery without a tourniquet and 1.53 (MD) better (95% CI 0.85 worse to 3.91 better) with a tourniquet (1 study; 199 participants); absolute difference was 1.53% better (0.85% worse to 3.91% better). Evidence was of low certainty, downgraded due to risk of bias and small number of participants. Serious adverse events: the risk of serious adverse events was probably higher with tourniquet; 26 of 898 (29 per 1000) reported events following surgery without a tourniquet compared to 53 of 901 (59 per 1000) with a tourniquet (RR 1.73, 95% CI 1.10 to 2.73) in 21 studies (1799 participants). Twenty-nine more per 1000 patients (95% CI 3 to 50 more per 1000 patients) had a serious adverse event with a tourniquet. Forty-eight (95% CI 20 to 345) participants would need to have surgery without a tourniquet to avoid one serious adverse event. This evidence was downgraded to moderate certainty due to risk of bias. Cognitive function: one study reported cognitive function as an outcome; however the data were incompletely reported and could not be extracted for analysis. Survival of implant: it is uncertain if tourniquet has an effect on implant survival due to very low certainty evidence (downgraded for bias, and twice due to very low event rates); 2 of 107 (19 per 1000) required revision surgery in the surgery with a tourniquet group compared to 1 of 107 (9 per 1000) without a tourniquet group at up to two years' follow-up (RR 1.44, 95% CI 0.23 to 8.92). This equates to a 0.4% (0.7% lower to 7% more) increased absolute risk in surgery with a tourniquet.

AUTHORS' CONCLUSIONS

Moderate certainty evidence shows that knee replacement surgery with a tourniquet is probably associated with an increased risk of serious adverse events. Surgery with a tourniquet is also probably associated with higher postoperative pain, although this difference may or may not be noticeable to patients. Surgery with a tourniquet does not appear to confer any clinically meaningful benefit on function, treatment success or quality of life. Further research is required to explore the effects of tourniquet use on cognitive function and implant survival, to identify any additional harms or benefits. If a tourniquet continues to be used in knee replacement surgery, patients should be informed about the potential increased risk of serious adverse events and postoperative pain.

Microdialysis for the Assessment of Intervertebral Disc and Vertebral Cancellous Bone Metabolism in a Large Porcine Model

BACKGROUND/AIM

It remains challenging to evaluate the in vivo pathophysiological biochemical characteristics in spine tissue, due to lack of an applicable model and feasible methods. The aim of this study was to apply microdialysis for the assessment of basic metabolites from the C3-C4 intervertebral disc, C3 vertebral cancellous bone and subcutaneous adipose tissue in a large porcine model.

MATERIALS AND METHODS

In 7 pigs, glucose, pyruvate, lactate and glycerol concentrations were evaluated in an 8-hour sampling period.

RESULTS

The mean lactate/pyruvate (L/P) ratios for the intervertebral disc and vertebral cancellous bone were comparable and exceeded the ischemic cut-off value of 25 for the entire sampling interval. For subcutaneous adipose tissue, the L/P ratio was below the ischemic cut-off.

CONCLUSION

This exploratory study confirms previous findings of ischemia in bone and the intervertebral disc. This encourages new microdialysis study designs in spine tissue employing large porcine models to create new knowledge and a greater understanding of the metabolism and pathogenesis in spine tissue.

Timing of Antimicrobial Prophylaxis and Tourniquet Inflation: A Randomized Controlled Microdialysis Study

BACKGROUND

Tourniquets are widely used during extremity surgery. In order to prevent surgical site infection, correct timing of antimicrobial prophylaxis and tourniquet inflation is important. We aimed to evaluate the time for which the free drug concentration of cefuroxime is maintained above the minimum inhibitory concentration (t > MIC) in porcine subcutaneous adipose tissue and calcaneal cancellous bone during 3 clinically relevant tourniquet application scenarios.

METHODS

Twenty-four female Danish Landrace pigs were included. Microdialysis catheters were placed bilaterally for sampling of cefuroxime concentrations in calcaneal cancellous bone and subcutaneous adipose tissue, and a tourniquet was applied to a randomly picked leg of each pig. Subsequently, the pigs were randomized into 3 groups to receive 1.5 g of cefuroxime by intravenous injection 15 minutes prior to tourniquet inflation (Group A), 45 minutes prior to tourniquet inflation (Group B), and at the time of tourniquet release (Group C). The tourniquet duration was 90 minutes in all groups. Dialysates and venous blood samples were collected for 8 hours after cefuroxime administration. Cefuroxime and various ischemic marker concentrations were quantified.

RESULTS

Cefuroxime concentrations were maintained above the clinical breakpoint MIC for Staphylococcus aureus (4 µg/mL) in calcaneal cancellous bone and subcutaneous adipose tissue throughout the 90-minute tourniquet duration in Groups A and B. Cefuroxime administration at the time of tourniquet release (Group C) resulted in concentrations of >4 µg/mL for approximately of 3.5 hours in the tissues on the tourniquet side. Furthermore, tourniquet application induced ischemia (increased lactate:pyruvate ratio) and cell damage (increased glycerol) in subcutaneous adipose tissue and calcaneal cancellous bone. Tissue ischemia was sustained for 2.5 hours after tourniquet release in calcaneal cancellous bone.

CONCLUSIONS

Administration of cefuroxime (1.5 g) in the 15 to 45-minute window prior to tourniquet inflation resulted in sufficient concentrations in calcaneal cancellous bone and subcutaneous adipose tissue throughout the 90-minute tourniquet application. Furthermore, tourniquet-induced tissue ischemia fully resolved 2.5 hours after tourniquet release.

CLINICAL RELEVANCE

Cefuroxime administration 15 to 45 minutes prior to tourniquet inflation seems to be a safe window. If the goal is to maintain postoperative cefuroxime concentrations above relevant MIC values, our results suggest that a second dose of cefuroxime should be administered at the time of tourniquet release.

Impact of Tourniquet Strategy on Perioperative Results of Modern TKA

Recent changes in perioperative management of total knee patients including tranexamic acid, multimodal pain management, and periarticular injection make previous data on tourniquet use during total knee arthroplasty (TKA) less relevant. The purpose of this study was to evaluate the effect of tourniquet use on short-term postoperative outcomes in the era of modern TKA. Our institutional database was utilized to retrospectively identify three cohorts (long, short, and no tourniquet) of consecutive patients after unilateral TKA with a single surgeon. These three groups were compared using analysis of variance (ANOVA) and post hoc Tukey's tests. Primary endpoints being hemoglobin index (difference in preoperative and postoperative hemoglobin), inpatient narcotic use, surgical time, length of hospital stay (total hours and % day1 discharges), and distance ambulated prior to discharge. The no-tourniquet group used significantly less narcotic than the short-tourniquet (2.4 vs. 2.9 morphine equivalent/hour, p = 0.004) and long-tourniquet groups (2.4 vs. 3.4 morphine equivalents/hour, p < 0.001). The no-tourniquet group ambulated significantly further than patients in the short (108 vs. 57 feet, p < 0.001) and long (108 vs. 76 feet, p < 0.001) groups. Finally, the no-tourniquet group had significantly shorter duration of hospitalization than the long-tourniquet group in both hours in the hospital (35 vs. 57 hours, p < 0.001) and % postoperative day 1 discharge (57 vs. 12%, p < 0.001). TKA without the use of a tourniquet is associated with less narcotic consumption and increased distance ambulated prior to discharge compared with cohorts of patients utilizing tourniquet for a short or long duration.

The effect of tourniquet uses on total blood loss, early function, and pain after primary total knee arthroplasty: a prospective, randomized controlled trial

Aims

The aim of this study was to examine whether tourniquet use can improve perioperative blood loss, early function recovery, and pain after primary total knee arthroplasty (TKA) in the setting of multiple-dose intravenous tranexamic acid.

Methods

This was a prospective, randomized clinical trial including 180 patients undergoing TKA with multiple doses of intravenous tranexamic acid. One group was treated with a tourniquet during the entire procedure, the second group received a tourniquet during cementing, and the third group did not receive a tourniquet. All patients received the same protocol of intravenous tranexamic acid (20 mg/kg) before skin incision, and three and six hours later (10 mg/kg). The primary outcome measure was perioperative blood loss. Secondary outcome measures were creatine kinase (CK), CRP, interleukin-6 (IL-6), visual analogue scale (VAS) pain score, limb swelling ratio, quadriceps strength, straight leg raising, range of motion (ROM), American Knee Society Score (KSS), and adverse events.

Results

The mean total blood loss was lowest in the no-tourniquet group at 867.32 ml (SD 201.11), increased in the limited-tourniquet group at 1024.35 ml (SD 176.35), and was highest in the tourniquet group at 1,213.00 ml (SD 211.48). The hidden blood loss was lowest in the no-tourniquet group (both p < 0.001). There was less mean intraoperative blood loss in the tourniquet group (77.48 ml (SD 24.82)) than in the limited-tourniquet group (137.04 ml (SD 26.96)) and the no-tourniquet group (212.99 ml (SD 56.35); both p < 0.001). Patients in the tourniquet group showed significantly higher levels of muscle damage and inflammation biomarkers such as CK, CRP, and IL-6 than the other two groups (p < 0.05). Outcomes for VAS pain scores, limb swelling ratio, quadriceps strength, straight leg raising, ROM, and KSS were significantly better in the no-tourniquet group at three weeks postoperatively (p < 0.05), but there were no significant differences at three months. No significant differences were observed among the three groups with respect to transfusion rate, thrombotic events, or the length of hospital stay.

Conclusion

Patients who underwent TKA with multiple doses of intravenous tranexamic acid but without a tourniquet presented lower total blood loss and hidden blood loss, and they showed less postoperative inflammation reaction, less muscle damage, lower VAS pain score, and better early knee function. Our results argue for not using a tourniquet during TKA.

Cite this article: Bone Joint Res 2020;9(6):322–332.

MicroRNA-153-3p increases autophagy in sevoflurane-preconditioned mice to protect against ischaemic/reperfusion injury after knee arthroplasty

The use of tourniquet during total knee arthroplasty (TKA) can result in ischaemia/reperfusion injury (IRI). Of interest, microRNAs (miRs) are reported to be involved in various kinds of IRI due to their ability in modulating autophagy. Therefore, the study aimed to investigate the effect of miR‐153‐3p on autophagy in IRI in vitro and in vivo under sevoflurane preconditioning. In the in vitro model, chondrocytes from naive mice were treated with 0% FBS alone or in combination with sevoflurane. Additionally, in vivo assays were conducted in mouse models with tourniquet‐induced IRI after TKA under or without sevoflurane preconditioning. The pathological observation in vivo validated that sevoflurane preconditioning protected the knee joint against IRI. Moreover, miR‐153‐3p expression was diminished in chondrocytes of the in vitro model and in cartilage tissue of the in vivo model, but its expression was appreciably up‐regulated in the presence of sevoflurane preconditioning. Mechanistic study showed that miR‐153‐3p disrupted the interaction between Bcl‐2 and Beclin1 by targeting Bcl‐2, thereby facilitating autophagy in chondrocytes under sevoflurane preconditioning. Furthermore, the experiments in human chondrocytes also verified the protective effects of miR‐153‐3p against IRI were realized through inhibiting Bcl‐2. Collectively, miR‐153‐3p overexpression blocks the interaction between Bcl‐2 and Beclin1 via down‐regulation of Bcl‐2 to promote autophagy of chondrocytes, thus protecting knee joint against IRI after TKA under sevoflurane preconditioning.

The effects of tourniquet use on blood loss in primary total knee arthroplasty for patients with osteoarthritis: a meta-analysis

Background

The tourniquet is a common medical instrument used in total knee arthroplasty (TKA). However, there has always been a debate about the use of a tourniquet and there is no published meta-analysis to study the effects of a tourniquet on blood loss in primary TKA for patients with osteoarthritis.

Methods

We performed a literature review on high-quality clinical studies to determine the effects of using a tourniquet or not on blood loss in cemented TKA. PubMed, Web of Science, MEDLINE, Embase, and the Cochrane Library were searched up to November 2018 for relevant randomized controlled trials (RCTs). We conducted a meta-analysis following the guidelines of the Cochrane Reviewer’s Handbook. We used the Cochrane Collaboration’s tool for assessing the risk of bias of each trial. The statistical analysis was performed with Review Manager statistical software (version 5.3).

Results

Eleven RCTs involving 541 patients (541 knees) were included in this meta-analysis. There were 271 patients (271 knees) in the tourniquet group and 270 patients (270 knees) in the no tourniquet group. The results showed that using a tourniquet significantly decreased intraoperative blood loss (P < 0.002), calculated blood loss (P < 0.002), and the time of operation (P < 0.002), but tourniquet use did not significantly decrease postoperative blood loss (P > 0.05), total blood loss (P > 0.05), the rate of transfusion (P > 0.05), and of deep vein thrombosis (DVT) (P > 0.05) in TKA.

Conclusions

Using a tourniquet can significantly decrease intraoperative blood loss, calculated blood loss, and operation time but does not significantly decrease the rate of transfusion or the rate of DVT in TKA. More research is needed to determine if there are fewer complications in TKA without the use of tourniquets.

Mechanisms by which hydrogen sulfide attenuates muscle function following ischemia-reperfusion injury: effects on Akt signaling, mitochondrial function, and apoptosis

Ischemia–reperfusion injury is caused by a period of ischemia followed by massive blood flow into a tissue that had experienced restricted blood flow. The severity of the injury is dependent on the time the tissue was restricted from blood flow, becoming more severe after longer ischemia times. This can lead to many complications such as tissue necrosis, cellular apoptosis, inflammation, metabolic and mitochondrial dysfunction, and even organ failure. One of the emerging therapies to combat ischemic reperfusion injury complications is hydrogen sulfide, which is a gasotransmitter that diffuses across cell membranes to exert effects on various signaling pathways regulating cell survival such as Akt, mitochondrial activity, and apoptosis. Although commonly thought of as a toxic gas, low concentrations of hydrogen sulfide have been shown to be beneficial in promoting tissue survival post-ischemia, and modulate a wide variety of cellular responses. This review will detail the mechanisms of hydrogen sulfide in affecting the Akt signaling pathway, mitochondrial function, and apoptosis, particularly in regards to ischemic reperfusion injury in muscle tissue. It will conclude with potential clinical applications of hydrogen sulfide, combinations with other therapies, and perspectives for future studies.

The Possible Pathophysiological Outcomes and Mechanisms of Tourniquet-Induced Ischemia-Reperfusion Injury during Total Knee Arthroplasty

Ischemia and reperfusion (I/R) injury induced by tourniquet (TQ) application leads to the release of both oxygen free radicals and inflammatory cytokines. The skeletal muscle I/R may contribute to local skeletal muscle and remote organ damage affecting outcomes after total knee arthroplasty (TKA). The aim of the study is to summarize the current findings associated with I/R injury following TKA using a thigh TQ, which include cellular alterations and protective therapeutic interventions. The PubMed database was searched using the keywords "ischemia reperfusion injury," "oxidative stress," "tourniquet," and "knee arthroplasty." The search was limited to research articles published in the English language. Twenty-eight clinical studies were included in this qualitative review. Skeletal muscle I/R reduces protein synthesis, increases protein degradation, and upregulates genes in cell stress pathways. The I/R of the lower extremity elevates local and systemic oxidative stress as well as inflammatory reactions and impairs renal function. Propofol reduces oxidative injury in this I/R model. Ischemic preconditioning (IPC) and vitamin C may prevent oxygen free radical production. However, a high dose of N-acetylcysteine possibly induces kidney injury. In summary, TQ-related I/R during TKA leads to muscle protein metabolism alteration, endothelial dysfunction, oxidative stress, inflammatory response, and renal function disturbance. Propofol, IPC, and vitamin C show protective effects on oxidative and inflammatory markers. However, a relationship between biochemical parameters and postoperative clinical outcomes has not been validated.

Downregulation of the long noncoding RNA MBNL1-AS1 protects sevoflurane-pretreated mice against ischemia-reperfusion injury by targeting KCNMA1

Total knee arthroplasty (TKA) is the most common and cost-effective treatment for older adults with long-standing osteoarthritis. During TKA, muscle cells suffer from prolonged oxygen deficiency, which leads to altered cell metabolism that reduces the energy demand and maintains cell homeostasis before blood flow is restored. This study focused on the role of the lncRNA muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) in protecting sevoflurane-pretreated mice against ischemia-reperfusion (I/R) injury after TKA, as well as the elucidation of the potential associated mechanism. Identification of differentially expressed lncRNAs was performed using the microarray dataset GSE21164, which was extracted from the GEO database. Target genes of the lncRNA were determined using Multi-Experiment Matrix (MEM), a dual-luciferase reporter gene assay, and KEGG enrichment analyses. The results showed that MBNL1-AS1 was overexpressed in skeletal muscle cells in mice, while KCNMA1, which was enriched in the cGMP-PKG signaling pathway, was negatively regulated by MBNL1-AS1. Furthermore, I/R mice displayed serious inflammatory reactions. Down-regulation of MBNL1-AS1 increased the expression of KCNMA1, PKGII, VASP, VEGF, Bcl-2, Cyclin D1, Cyclin D3, and Cdc 42 but decreased the expression of Bax, cleaved caspase-3, and cleaved PARP. Furthermore, upon MBNL1-AS1 upregulation, the rate of cell apoptosis increased while the rate of cell proliferation decreased. Our data suggested that down-regulated lncRNA MBNL1-AS1 might promote the proliferation and inhibit the apoptosis of skeletal muscle cells by upregulating KCNMA1 expression via activation of the cGMP-PKG signaling pathway, thus protecting sevoflurane-pretreated mice against I/R injury after TKA.

A potential therapeutic target identified by researchers in China could help limit damage to tissues following osteoarthritic knee surgery. A total knee arthroplasty can alleviate symptoms of end-stage osteoarthritis, but the surgery requires use of a tourniquet. This temporarily cuts blood supply to tissues and can trigger severe ischemia-reperfusion (I/R) injury, tissue damage caused by blood flow returning after oxygen deficiency. Shao-Nan Yu and co-workers at the China-Japan Union Hospital of Jilin University, Changchun, demonstrated that lowering expression of a particular RNA molecule following surgery could limit I/R damage. They found that the molecule was over-expressed in mice during I/R injury. This overexpression limited activation of a signalling pathway and an associated protein vital to the chemical balance of cell membranes and healthy muscle cell contraction.

Silicone ring tourniquet versus pneumatic cuff tourniquet in total knee arthroplasty surgery: A randomised comparative study

Introduction

The aim of the present study was to compare a silicone ring tourniquet (SRT) and a classic pneumatic cuff tourniquet (PT) in patients undergoing total knee replacement. We have compared the impact on the glycolytic activity caused by the ischaemia applied to the limb during the surgery.

Material and methods

140 patients that underwent total knee arthroplasty (TKA) were randomised in two groups. Serum lactate determination was made by reactive strips of enzymatic-amperometric detection, 5 min before tourniquet application and 5 min after tourniquet removal.

Results

The mean tourniquet time was similar for both groups (p 0.13). Postoperative serum lactate levels were higher with statistical significance than the preoperative levels and with a positive Pearson´s correlation in the overall cases. The postoperative serum lactate levels where higher in the PT group (4.097 ± 2.248 mmol/L) than the SRT group (3.499 ± 1.566 mmol/L). There was no significant difference (p 0.07) to be able to affirm that there was a difference of the anaerobic metabolism according to the tourniquet system used.

Discussion

Ischaemia applied to the lower extremity during knee replacement surgery can produce tissue injury. Serum lactate determination allows comparison of the ischaemic changes during TKA surgery caused by two different tourniquet systems.

Conclusions

SRT may be not disadvantageous compared to the classic PT from the impact on the glycolytic activity caused by the ischaemia.Level of evidence II.

Monitoring of glycolytic activity secondary to ischaemia in knee replacement surgery

OBJECTIVES

To non-invasively assess tissue lesion secondary to ischaemia applied during knee replacement surgery. Secondary objectives: to assess whether this lesion correlates with the duration of ischaemia and whether instrumental and gender variables influence it.

MATERIAL AND METHODS

Prospective cohort study. Pre and postoperative serum lactate levels have been determined as an indicator of glycolytic activity secondary to ischaemia in 88 patients. Serum lactate determination was performed by reactive strips of enzymatic-amperometric detection on capillary blood.

RESULTS

Preoperative serum lactate levels (mean and SD): 2.467±1.036 mmol/L. Postoperative serum lactate levels: 3.938±2.018 mmol/L. Ischaemia time 102.98±18.25minutes. Postoperative serum lactate levels were significantly higher than preoperative lactate levels. There are no statistical differences according to the time that the ischaemia was prolonged, gender or type of instrumentation used.

CONCLUSIONS

In our study, postoperative serum lactate values were significantly higher than preoperative lactate values, with no correlation to the duration of ischaemia during knee replacement surgery.

The emerging role of microdialysis in diabetic patients undergoing amputation for limb ischemia

Lower limb ischemia in diabetic patients is a result of macro- and microcirculation dysfunction. Diabetic patients undergoing limb amputation carry high mortality and morbidity rates, and decision making concerning the level of amputation is critical. Aim of this study is to evaluate a novel microdialysis technique to monitor tissue microcirculation preoperatively and predict the success of limb amputation in such patients. Overall, 165 patients with type 2 diabetes mellitus undergoing lower limb amputation were enrolled. A microdialysis catheter was placed preoperatively at the level of the intended flap for the stump reconstruction, and the levels of glucose, glycerol, lactate and pyruvate were measured for 24 consecutive hours. Patients were then amputated and monitored for 30 days regarding the outcome of amputation. Failure of amputation was defined as delayed healing or stump ischemia. Patients were divided into two groups based on the success of amputation. There was no difference between the two groups regarding gender, ASA score, body mass index, comorbidities, diagnostic modality used, level of amputation, as well as glucose, glycerol, and pyruvate levels. However, local concentrations of lactate were significantly different between the two groups and lactate/pyruvate (L/P) ratio was independently associated with failed amputation (threshold defined at 25.35). Elevated preoperative tissue L/P ratio is independently associated with worse outcomes in diabetic patients undergoing limb amputation. Therefore, preoperative tissue L/P ratio could be used as a predicting tool for limb amputation's outcome, although more clinical data are needed to provide safer conclusions.