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

Rough and jagged edges of the bone were rounded off so as to prevent entanglement of the bead chain. The antibiotic bead chain was then implanted; the number of beads and the size of the chain were determined by the size of the cavity. All wounds were closed primarily. If the wound closure was found to be under tension, as in cases of tibial wound closure, release incisions were made before the closure. The limb was immobilised in plaster of Paris cast or using an external fixator.

Noncommercial fabrication of beads

In 14 cases which the commercially prepared PMMA beads (Septopal; E. Merck, Hamburg, Germany) were not available, handmade beads impregnated with cefuroxime were used.

As gentamycin in powder form was not available in India and liquid gentamycin does not mix uniformly with bone cement, cefuroxime was used in this study: 8 g of cefuroxime powder was mixed homogenously in a sterile bowl with 40 g of PMMA polymer. To this, 20 ml of PMMA monomer liquid was added. When the mixture became doughy and non-sticky, beads of 5- to 8-mm size were handrolled. The beads were threaded onto a steel wire and the ends were knotted (Fig. 1).

Postoperative protocol

Systemic antibiotics, to which organisms were sensitive, were given for 7 days. If organisms were found to be resistant to all antibiotics, broad-spectrum antibiotics were administered. Overflow drains were used without suction for the first 24 to 48 hours. Sutures were removed after 10 days. After 3 weeks, the beads were removed and bone grafting was done in 26 cases, depending on the status of the fracture and the size of the cavity (Fig. 2). In 5 cases of infected gap nonunion, ring fixators were applied and bone transport was performed.

Follow-up

All patients were followed up at 6-week intervals in the initial 3 months, then every 3 months for at least 2 years. The mean follow-up period was 3.7 years (range, 2.0-5.0 years). The results were graded as follows:

Good: No clinical features of infection with erythrocyte sedimentation rate returning to normal levels, primary healing of the wound without any recurrence of the discharging sinus, and complete healing of fracture.

Fair: No clinical signs of infection with erythrocyte sedimentation rate returning to normal levels, primary healing of the wound, and delayed fracture healing.

Poor: Recurrence of the sinus with discharge, and radiographic signs of infected nonunion.

RESULTS

Site of infection, duration of infection, and organism responsible for the infection are shown in Tables 1, 2, and 3, respectively. The organisms were found to be sensitive to gentamycin in 26 cases and resistant in 19 cases. They were sensitive to cefuroxime in 14 cases, cloxacillin in 11, ampicillin in 8, and cotrimoxazole in 5; in 7 cases, the organisms were resistant to all antibiotics tested. 38 wounds healed primarily, whereas 7 healed by secondary intention, of which 4 healed by epithelisation and 3 required secondary closure. At 6 weeks' follow-up, there was recurrence of drainage in 6 cases, all of which belonged to Group 1. There was no difference in the clinical outcome between the cases treated with Septopal or those treated with handmade beads.