Bone wax reduces blood loss in unicompartmental knee arthroplasty for osteoarthritis

BACKGROUND: Unicompartmental knee arthroplasty (UKA) offers less trauma and faster recovery in the treatment of osteoarthritis of the knee. Bone oozing in UKA may result in hematoma and complications after the operation.METHODS: A prospective case-control study was conducted to analyze the effect of bone wax in reducing blood loss following UKA. We analyzed 116 patients with medial knee osteoarthritis who underwent UKA in the period between April 2020 and April 2021. Visible blood loss and total blood loss were evaluated, and Hb level of the patient postoperation was recorded. Also, circumference of the knee was measured after the operation. Visual Analog Scale (VAS) scores were used, and severe pain rate was calculated. Other complications such as wound healing, hemoarthrosis, infection, deep vein thrombosis (DVT), and transfusion were recorded.RESULTS: The bone wax group had less total blood loss (232.3±68.4 in group A, 263.7±70.1 in group B; P=0.032). The mean circumference of the knee increased 2.73 cm (range 1.5-4.1 cm) in group B and 1.65 cm (range 1.2-3.4 cm) in group A at 3 days postoperation and the difference was significant (P<0.001). The rate of severe pain that occurred was significantly lower in group A than in group B (8.6% vs. 22.4%; P=0.040). Patients in the bone wax group were more satisfied with UKA (89.7% in group A, 74.1% in group B; P=0.030). No infection occurred and blood transfusion was not performed in any patient. 2 patients in group A and 7 patients in group B underwent knee cavity aspiration due to hemoarthrosis. There was one patient who experienced delayed wound healing in both groups and 1 DVT in group B.CONCLUSIONS: The use of bone wax can reduce blood loss in UKA, and it does not increase the rate of complications at short-term follow-up. More degradable bone waxes with good biocompatibility should be further investigated.