Two hundred twenty-seven patients with hip or knee arthritis were randomized to receive drainage or no drainage after hip (n=167) or knee (n=60) replacement. The primary outcome of interest was the size of the joint hematoma as measured by ultrasonography on the third-day post-surgery. Secondary outcomes included pain levels assessed by VAS and the presence of wound exudation. Outcomes were assessed on the third day after surgery. Overall, the results of the study revealed no significant difference in hematoma size based on drainage use. However, significant correlations were found between larger hematoma sizes and higher pain levels, as well as the presence of wound exudation, particularly in hip replacement patients. The study suggests that ultrasonography can effectively identify patients at risk for higher pain and wound exudation due to larger hematomas, potentially guiding clinical decisions for hematoma management.