[Treatment of osteomyelitis by local antibiotics using a portable electronic micropump]

Systemic administration of antibiotics in osteoarticular infections is characterized by: 1) systemic side effects: 2) questionable penetration of the antibiotic into the infected and ischaemic areas: 3) mandatory hospitalization for prolonged administration of antibiotics. Aware of these difficulties, orthopedic surgeons have long been seeking an effective method of local antibiotic administration. The authors report their original experience with the use of an external, portable electronic micro pump for continuous local delivery of antibiotics in conjunction with surgical debridement, in the treatment of osteomyelitis.

Ten patients with active chronic osteomyelitis, were treated with surgical debridement and local antibiotic therapy. On the basis of the sensitivity disk findings, vancomycin or amikacin was delivered locally through an external portable, electronically programmable micro pump. To connect the pump with the infected site Groshong or Buchwald catheters were employed. The reservoir of the pump was refilled every 10-15 days.

The duration of symptoms ranged from six months to fifteen years. All patients had undergone at least one previous unsuccessful treatment consisting of surgical debridement and/or prolonged intravenous antibiotic therapy. The duration of the infusion therapy ranged from 80 to 207 days (mean 109 +/- 37.7). At 33.7 +/- 5.6 months follow-up (range twenty-one to thirty-nine months) eight patients out of nine (one patient was lost to follow-up), showed no recurrence of the infection as manifested by clinical, laboratory and imaging data. Serum vancomycin and amikacin levels, measured at different intervals from the beginning of therapy, were always well below the recommended through levels for systemic infusion. There were no side effects linked to the prolonged administration of antibiotics, no technical complications connected with the implantation and removal of the catheter and no infections of inflammation of subcutaneous tissue where the catheter had been placed or of the skin around the catheter.

The use of subcutaneous, totally implantable infusion drugs pumps, as proposed by Clayton, Perry and co-workers (1986) allows: 1) to maintain adequate local levels of a wide variety of antibiotics for a long period of time, avoiding systemic toxicity; 2) to stop the infusion in case of adverse reactions (allergic response): 3) to administer the treatment on an outpatient basis. Our original proposal of an externally portable micro pump adds the following advantages: 1) it is less invasive: 2) no risk of infection of the subcutaneous pocket where the pump is lodged: 3) better stability of the antibiotic, being at ambient temperature instead of at nearly 30 degrees C: 4) much lower cost, the external pump being less expensive than an implantable one and is reusable.

Our experience shows: 1) the simplicity and limited invasiveness of this technique, which, without excluding other forms of therapy, allows to deliver antibiotics in the infected focus for months; 2) the absence of side effects and technical complications; 3) the good quality of life of the patients during the treatment; 4) the low cost for the health care system, since the patients are followed-up and the reservoirs refilled on an out-patient basis.