Unexpected positive intraoperative cultures (UPIC) at index osseointegration do not lead to increased postoperative infectious events.

Introduction: The most common complication following transcutaneous osseointegration for amputees is infection. Although an obvious source of contamination is the permanent stoma, operative site contamination at the time of implantation may be an additional source. This study investigates the impact of unexpected positive intraoperative cultures (UPIC) on postoperative infection. Methods: Charts were reviewed for 8 patients with UPIC and 22 patients with negative intraoperative cultures (NIC) who had at least 1 year of post-osseointegration follow-up. All patients had 24 h of routine postoperative antibiotic prophylaxis, with UPIC receiving additional antibiotics guided by culture results. The main outcome measure was postoperative infection intervention, which was graded as (0) none, (1) antibiotics unrelated to the initial surgery, (2) operative debridement with implant retention, or (3) implant removal. Results: The UPIC vs. NIC rate of infection management was as follows: Grade 0, 6/8 $=$ 75 % vs. 14/22 $=$ 64 %, p $=$ 0.682; Grade 1, 2/8 $=$ 25 % vs. 8/22 $=$ 36.4 % (Fisher's p $=$ 0.682); Grade 2, 1/8 = 12.5 % vs. 0/22 $=$ 0 % (Fisher's p $=$ 0.267); Grade 3, 0/8 $=$ 0 % vs. 1/22 $=$ 4.5 % (Fisher's p $=$ 1.000). No differences were statistically significant. Conclusions: UPIC at index osseointegration, managed with directed postoperative antibiotics, does not appear to increase the risk of additional infection management. The therapeutic benefit of providing additional directed antibiotics versus no additional antibiotics following UPIC is unknown and did not appear to increase the risk of other adverse outcomes in our cohort.