Thai et al. Journal of Orthopaedic Surgery and Research (2021) 16:535 https://doi.org/10.1186/s13018-021-02686-x RESEARCH ARTICLE Open Access Factors affecting the outcome of lower extremity osteomyelitis treated with microvascular free flaps: an analysis of 65 patients Duy Quang Thai1,2, Yeon Kyo Jung1, Hyung Min Hahn1 and Il Jae Lee1* Abstract Background: Free flaps have been a useful modality in the management of lower extremity osteomyelitis particularly in limb salvage. This study aimed to determine the factors affecting the outcome of free flap reconstruction in the treatment of osteomyelitis. Methods: This retrospective study assessed 65 osteomyelitis patients treated with free flap transfer from 2015 to 2020. The treatment outcomes were evaluated in terms of the flap survival rate, recurrence rate of osteomyelitis, and amputation rate. The correlation between outcomes and comorbidities, causes of osteomyelitis, and treatment modalities was analyzed. The following factors were considered: smoking, peripheral artery occlusive disease, renal disease, diabetic foot ulcer, flap types, using antibiotic beads, and negative pressure wound therapy. Result: Among the 65 patients, 21 had a severe peripheral arterial occlusive disease. Osteomyelitis developed from diabetic foot ulcers in 28 patients. Total flap failure was noted in six patients, and osteomyelitis recurrence was noted in eight patients, for which two patients underwent amputation surgery during the follow-up period. Only end-stage renal disease had a significant correlation with the recurrence rate (odds ratio = 16.5, p = 0.011). There was no significant relationship between outcomes and the other factors. Conclusion: This study showed that free flaps could be safely used for the treatment of osteomyelitis in patients with comorbidities and those who had osteomyelitis developing from diabetic foot ulcers. However, care should be taken in patients diagnosed with end-stage renal disease. Keywords: Osteomyelitis, Free flaps, Diabetic foot ulcer, Peripheral arterial occlusive disease Background infection, obliterate dead space, and cover soft-tissue de- Osteomyelitis (OM) has been one of the most difficult fects. Over the last three decades, free tissue transfer has complications. Patients with OM have to face the possi- been an important option that can overcome the limita- bility of amputation that can adversely affect their qual- tions of typical methods such as skin grafts, local flaps, ity of life [1]. The treatment of OM aims to eradicate or muscle flaps. Free flaps can provide a wide range of tissues including skin, muscle, bone, or a combination of these to allow for more aggressive resection of affected * Correspondence: [email protected] tissues. Consequently, this decreases the recurrence rate 1Department of Plastic and Reconstructive Surgery, Ajou University School of Medicine, 164 World cup-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16499, of osteomyelitis and increases the rate of limb salvage. Republic of Korea Numerous studies have reported favorable results of Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Thai et al. Journal of Orthopaedic Surgery and Research (2021) 16:535 Page 2 of 7 using free flaps in the treatment of osteomyelitis [2–4]. supplemented with traditional angiography. All of the However, to the best of our knowledge, factors affecting patients with severe stenosis (greater than 75% of the the operative results have not been well established. diameter) or total occlusion underwent percutaneous Therefore, we aimed to determine whether co-morbidities transluminal angioplasty. Serial debridement was per- and other factors could influence the outcome of formed to radically resect the infected tissues including using free flaps in the treatment of lower extremity soft tissue and bone. Deep soft tissue and bone cultures osteomyelitis. were taken to confirm the diagnosis and direct the anti- biotic treatment. Patients received broad-spectrum anti- Patients and methods biotic treatment before culture results, and specific This retrospective study was approved by the Institu- antibiotics following the confirmation of culture results. tional Review Board of our medical center (AJIRB-MED- Antibiotic beads (Vancomycin) were used in 15 cases MDB-16-402) and we assessed patient records from and NPWT was applied in 44 cases. 2015 to 2020. Sixty-five patients diagnosed with osteo- Reconstruction was performed once all the infected myelitis and treated with free flaps were included. The tissues were resected and the wound had a good blood average follow-up period was 18 months (range, 6 to 48 supply. The operation began with appropriate debride- months). Patients with incomplete reports or those who ment followed by dissection of the recipient vessels. followed up for less than 6 months were excluded. Pa- Major arteries with higher blood pressure were preferred tients under 16 years of age were also excluded from this over small branches as the recipient vessels. These study. branches were preserved to prevent further damage. The following data was collected via patient charts: Arteriorrhaphy was attempted in all cases with an end- demography, radiographs of the lower extremity, details to-side approach; an end-to-end anastomosis was per- of the wounds and treatment, complications, and follow- formed if the end-to-side approach was unsuccessful. up information. The outcomes of treatment were The type of flap was decided according to the size and evaluated based on flap success rate, recurrence rate of depth of the defect. Although the fasciocutaneous flap OM, and amputation rate during the follow-up period. was most commonly used, myocutaneous flaps were se- The correlation between outcomes and comorbidities, lected to obliterate dead space in cases with deep causes of osteomyelitis, and treatment modalities were defects. analyzed. Case reports Statistical analysis Case 1 Categorical variables were summarized as frequencies A 56-year-old male diabetic patient was referred to our and percentages while continuous variables were department with diabetic foot osteomyelitis. He had expressed as mean and standard deviations. Chi-square been hypertensive for 20 years and diabetic for 24 years. and Fisher’s exact tests were used to analyze the differ- CT-angiography revealed severe stenosis of the popliteal ence in flap survival rate and the recurrence rate of artery and total occlusion of the dorsalis pedis artery of osteomyelitis in patients with and without the following his right leg. Immediate balloon angioplasty was per- factors: smoking, peripheral artery occlusive disease formed. Serial debridement and minor amputation were (PAOD), end-stage renal disease (ESRD), diabetic foot done—his fourth and fifth toes were resected. A fascio- ulcer, flap types, using antibiotic beads, and negative cutaneous anterolateral thigh free flap (ALT) was ap- pressure wound therapy (NPWT). A p value < 0.05 was plied to completely cover the defect with antibiotic considered statistically significant. All statistical analyses beads inserted underneath. Due to atherosclerosis, the were performed using SPSS 20.0. (IBM Corp., Armonk, anastomosis was performed in an end-to-side fashion to NY, USA). the anterior tibial artery proximal to the occlusion. The flap healed uneventfully and the patient was ambulatory Treatment protocol during 8 months of follow-up (Fig. 1). The diagnosis of osteomyelitis was based on clinical symptoms; laboratory tests including WBC, ESR, CRP, Case 2 tissue culture, and bone culture; and radiological images A 55-year-old man, diabetic for 20-years, was admitted including plain X-rays, MRI, and bone scans. Simultan- for the development of wet gangrene in his fifth toe. The eously, patients were thoroughly examined for cardiac, toe was resected, and serial debridement was performed. endocrine, and renal conditions. These conditions were Preoperative angioplasty indicated the absence of blood managed by specialist physicians whenever necessary. flow from the posterior tibial artery to the pedal arch Lower extremity blood vessel status was also carefully due to total occlusion. He underwent balloon angio- evaluated. If CT-angiography was unclear, it was plasty of the left posterior tibial artery and plantar artery. Thai et al. Journal of Orthopaedic Surgery and Research (2021) 16:535 Page 3 of 7 Fig. 1 Case 1. A Diabetic foot infection. B, C Ischemic defect following