Comparison of Pain and Complications between Outpatients and Inpatients Treated with Bone Marrow Aspirate Concentrate for Knee Osteoarthritis

Bone marrow aspirate concentrate (BMAC) has been increasingly used as an injectable treatment for knee osteoarthritis (OA). However, there remains a lack of studies on the pain and complications associated with BMAC treatment. This study compared the pain and complications of BMAC treatment between outpatients and inpatients with Kellgren-Lawrence grade II-III knee osteoarthritis (OA) during a follow-up period of ≥3 months. This study included 40 outpatients (40 knees) and 80 inpatients (80 knees) as controls who received BMAC articular injections for knee OA between December 2023 and March 2024. Outpatients were administered BMAC under local anesthesia alone, whereas inpatients were administered BMAC under local anesthesia and intravenous anesthesia. The outcomes were the visual analog scale (VAS) pain score during the BMAC procedure and the complications associated with harvest and injection sites. The mean VAS pain score in the outpatient group was significantly higher than that in the inpatient group during trocar insertion (5.2 vs. 1.3, <i>p</i> < 0.05) and bone marrow aspiration (6.2 vs. 1.4, <i>p</i> < 0.05), but it was similar between the two groups during BMAC injection (2.2 vs. 2.3, <i>p</i> = 0.858). Transient post-treatment complications were observed in 17.5% (7/40) of outpatients and 16.3% (13/80) of inpatients. No significant differences were observed in complications between the two groups, all of which were resolved within 2 months without any specific problem. Moreover, no major complications occurred in any group. In conclusion, outpatients who received only local anesthesia reported significant pain during BMAC treatment. The addition of intravenous anesthesia is necessary to alleviate pain during the BMAC procedure.