Use of antibiotic-loaded polymethyl methacrylate beads in the management of musculoskeletal sepsis-a retrospective study

Journal of Orthopaedic Surgery, Jun 2003 by Mohanty, S P, Kumar, M N, Murthy, N S

ABSTRACT

Purpose. To assess the use of antibiotic-loaded polymethyl methacrylate beads in the management of chronic osteomyelitis of different aetiologies: infected osteosynthesis, infected open fractures, and haematogenous osteomyelitis.

Methods. Records of 49 patients with chronic osteomyelitis who were treated at Department of Orthopaedics, Kasturba Medical College, from 1995 to 1999 were studied retrospectively. The diagnosis of chronic osteomyelitis was made on the basis of clinical and radiographic features. Of the 49 patients, 4 had haematogenous osteomyelitis, which later proved to be tuberculosis, and were thus excluded. Antibiotic-loaded acrylic beads were implanted in the remaining patients after thorough debridement. The implant was removed primarily in 16 patients with infected osteosynthesis, who then underwent decompression and sequestrectomy. All wounds were closed primarily. Peri-operative antibiotics were given for 7 days. Beads were removed at the end of 3 weeks followed by bone grafting in 26 patients. Patients were followed up for an average period of 3.7 years.

Results. The infective organisms were sensitive to gentamycin in 26 cases and resistant in 19 cases; 14 cases were sensitive to cefuroxime, 11 to cloxacillin, 8 to ampicillin, and 5 to cotrimoxazole. Seven cases were resistant to all antibiotics tested. Of the 19 patients with gentamycin-resistant infection, only one had a poor result. No adverse systemic side-effects such as ototoxicity or nephrotoxicity were seen. Infection did not recur in 39 patients, but 6 patients had low-grade persistent infection at the last follow-up visit.

Conclusion. In chronic infections, especially those following osteosynthesis, antibiotic beads are a valuable adjuvant. The most valuable advantage is that the wound can be closed primarily, thereby reducing the incidence of nosocomial infections and requirement of nursing care.

Key words: antibiotic-loaded polymethyl methacrylate beads; chronic osteomyelitis

INTRODUCTION

Optimal treatment of musculoskeletal infections often requires a combined surgical and antimicrobial approach. Osteomyelitis, however, is not consistently treated with success in this way, despite the extensive array of antibiotics currently available. Although such drugs have vastly improved the prognosis of acute osteomyelitis, they have not been successful in the management of chronic osteomyelitis or in surgical sepsis following internal fixation. The frequent recurrence of sepsis, despite intensive treatment with both surgery and prolonged parenteral administration of antimicrobial agents, may result in persistence or relapse of the infection and suggests that many fundamental questions remain unanswered. Buchholz et al.1 proposed the concept of local delivery of antibiotics as a means of preventing infection associated with replacement arthroplasty. Klemm2 later extended this concept to the treatment of chronic osteomyelitis. In this study, we assessed the efficacy and difficulties encountered during the use of antibiotic-loaded polymethyl methacrylate (PMMA) beads in different types of chronic osteomyelitis.

MATERIALS AND METHODS

We studied records of 49 patients, who had chronic osteomyelitis of various aetiologies, and were treated in our institution from July 1995 to June 1999 retrospectively. Four patients had haematogenous osteomyelitis, but the infection was later shown to be tuberculosis, and these patients were thus excluded from the study. Of the 45 patients, 37 were men and 8 were women. The median age at presentation was 34.8 years (range, 18.0-58.0 years). The diagnosis of chronic osteomyelitis was made on the basis of clinical and radiographic features of infection that were present for more than 12 weeks. Patients were divided into 3 groups according to the primary cause of infection: patients with infected osteosynthesis (Group 1), those with infection following open fractures (Group 2), and those with haematogenous osteomyelitis (Group 3). All patients had undergone at least one operation before admission, with an average of 3 operations, in an attempt to eradicate the infection before implantation of antibiotic-loaded PMMA beads.

Preoperative protocol

Samples of discharge from all sinuses and wounds were taken for culture and antibiotic sensitivity assays. Radiographic assessment was made to detect the presence of sequestra and implant loosening.

Operative procedure

Surgery was performed in 2 stages. In the first stage, the wound was explored through the pre-existing scar. If the draining sinus tract was found to be away from the previous scar, it was left alone. All osteosynthetic materials when present were removed except for those in 6 patients in whom there was no loosening of the implants and the fractures had not healed well. The implants were not removed with the hope of allowing the fracture to unite. All unhealthy granulation tissue was removed. The cavities were decompressed, curetted, and thoroughly washed out with copious quantities of normal saline.