Patient Acceptable Symptom State Thresholds for the Knee Society Score, Oxford Knee Score, and 36-Item Short Form Survey Ten Years Following Unicompartmental Knee Arthroplasty.

BACKGROUND: The patient acceptable symptom state (PASS) refers to a cutoff value on any patient-reported outcome measures (PROMs) scale, beyond which patients consider themselves as having achieved an acceptable outcome. This study aimed to identify PASS thresholds for knee-specific and generic PROMs at 10 years post-unicompartmental knee arthroplasty (UKA). METHODS: There were 269 patients who underwent UKA for medial osteoarthritis from 2004 to 2007 at a single institution and were surveyed preoperatively and 10 years postoperatively using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), 36-Item Short Form Survey (SF-36) Mental Component Score (MCS), and SF-36 Physical Component Score (PCS). Treatment outcomes and expectations were assessed using an anchor question, and PASS attainment was determined using the Youden index on a receiver operating characteristic (ROC) curve. Also, a similar study that identified 2-year long-term PROM PASS thresholds for UKA was referenced and compared. RESULTS: Overall, 91.1% reported acceptable outcomes. The area under the curve for ROCs of KSKS, OKS, and PCS were 0.80, 0.75, and 0.71, respectively. The area under the curve for ROCs of KSFS and MCS were both 0.64. The PASS thresholds were 67.5 for KSFS, 70.5 for KSKS, 39.5 for OKS, 44.6 for PCS, and 43.8 for MCS. Patients who achieved a PASS were at least 3 times more likely to have satisfactory outcomes. CONCLUSIONS: To our knowledge, this is the first study that identified 10-year long-term PROM PASS thresholds for UKA. Accounting for our finding that a decade-long follow-up yielded lower PASS thresholds, time-specific UKA PROM PASS thresholds should be considered. LEVEL OF EVIDENCE: III.

Bone Wax Is Effective in Reducing Blood Loss After Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is associated with major blood loss and blood transfusion is often required. This study aimed to evaluate the efficacy of bone wax in reducing blood loss and transfusion rates after TKA. METHODS: A prospective randomized controlled study that included 100 patients undergoing primary unilateral TKA with cement was conducted in a tertiary center between March 2014 and June 2014. The bone wax group received 2.5 g of bone wax, applied onto the uncovered bone around the prostheses and the nail holes before the tourniquet was released, whereas the control group had hemostasis achieved using electrocautery only. Total blood loss was calculated using the hemoglobin balance method. RESULTS: There were no demographic differences between the 2 groups. The preoperative serum hemoglobin levels were comparable between the 2 groups. The drop in serum hemoglobin levels at 24 h post-TKA was 1.6 ± 0.9 and 2.1 ± 1.1 g/dL in the bone wax and control groups respectively (P = .021), while the drop in serum hemoglobin levels at 72 h post-TKA was 2.7 ± 1.1 and 3.6 ± 1.2 g/dL respectively (P = .013). Total blood loss at 72 h post-TKA was 987.9 and 1183.5 mL for the bone wax and control groups respectively (P = .017). There was no adverse event associated with the use of bone wax at the 3-month follow-up. CONCLUSION: The application of bone wax in TKA was safe and effective for reducing total blood loss and maintaining higher hemoglobin levels.