Ultrasound-guided genicular nerves block: an analgesic alternative to local infiltration analgesia for total knee arthroplasty: A noninferiority, matched cohort study.

BACKGROUND: Standard analgesic strategies for total knee arthroplasty employ local infiltration analgesia. Blockade and radiofrequency ablation of the genicular nerves are effective treatments for patients with chronic pain because of knee osteoarthritis. OBJECTIVE: To test the noninferiority of the analgesic effect of genicular nerves block in comparison with local infiltration analgesia after 24 h of total knee arthroplasty. DESIGN: Prospective cohort study. SETTING: Perioperative setting. PATIENTS: Thirty-five patients scheduled for total knee arthroplasty were prospectively included in the study and compared with 35 patients in a retrospective cohort. INTERVENTION: Genicular nerve blocks in the prospective cohort were compared with local infiltration analgesia in the retrospective cohort. MAIN OUTCOME MEASURES: The pain numeric rating scale and the cumulative opioid consumption in oral morphine equivalents during the first 24 h. RESULTS: We conducted propensity score-matched analyses of patients using acute postoperative pain-related risk covariates. After one-to-one propensity score matching, 21 patients were included in the local infiltration analgesia group and 21 in the genicular nerve block group. The median difference in numeric rating score at rest at 24 h was -0.99 [95% confidence interval (CI), -1.99 to 0.5, P = 0.012] on the unmatched cohort and -1.9 (95% CI, -2 to 0, P = 0.002) on the matched cohort (meeting the noninferiority criteria, Δ=1). The median difference in cumulative opioid consumption was 2.5 mg (95% CI, -13.5 to 2.5, P < 0.001) for the unmatched cohort and 4.99 mg (95% CI, -11.5 to 2.5, P < 0.001) on the matched group (meeting the noninferiority criteria, Δ = 21 mg). CONCLUSION: Local infiltration analgesia and genicular nerve block are comparable in terms of analgesic results. Therefore, genicular nerves block is an alternative to local infiltration analgesia in patients undergoing total knee arthroplasty. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT04024319.

Severe and morbid obesity and transfusional risk in total knee arthroplasty: An observational study.

BACKGROUND: Severe and morbid obesity (Class II -III) represents a challenge for successful knee surgery. There isn't consensus on what influence body mass index has on blood loss and on red blood cell (RBC) transfusion during total knee arthroplasty (TKA). The objective was to determine blood loss and transfusion needs in severe and morbid obese patients undertaking TKA. METHODS: We recorded retrospectively all patients undergoing TKA. Obesity was assessed according to WHO guidelines. Perioperative haemoglobin and treatments for its optimisation were recorded. Blood losses were estimated from specific formulae for lost red-cell mass and percentage of lost blood volume. RESULTS: 922 patients were included: 35.90% were obese Class I and 18.76% obese Class II - III. Estimated blood volume was 4390  ±â€¯â€¯470 ml, 4736  ±â€¯â€¯423 ml and 5030 ±â€¯464 ml among non-obese, obese Class I and obese Class II-III, respectively (P < 0.001). The global estimated blood volume (EBV) lost was 1502  ±â€¯â€¯680 ml without differences between the three groups. However, the percentage of lost blood volume was lower in obese Class II -III (29.65%) than in non-obese (33.55%) and obese Class I (30.97%) (P < 0.005). Transfusion rates were 12.7%, 12.1% and 6.4% for non-obese, obese Class I and Class II -III, respectively (P = 0.062). A negative transfusion risk was predicted for Class II -III patients. CONCLUSIONS: Severely and morbidly obese patients did not show greater blood loss nor higher RBC transfusion needs after primary TKA than non-obese and obese Class I patients. This could be because obese Class II -III patients had higher EBV but similar RBC losses.