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Background: Prevention of infection associated with uncemented orthopaedic implants could lead to improved implant stability and better patient outcomes. We hypothesized that coating porous metal implants with antibiotic-containing microspheres would prevent infections in grossly contaminated wounds., Methods: Bioresorbable polymer microspheres containing tobramycin were manufactured and pressed into porous metal cylinders that were then implanted into radial defects in rabbits. Control implants that did not contain antibiotic microspheres were also implanted into the contralateral limbs. Each implant was then contaminated with Staphylococcus aureus prior to closure of the wound. The animal was euthanized after clinical signs of infection appeared, or at two weeks after surgery. Periprosthetic tissue was cultured for the presence of S. aureus, and integration of the implant with the surrounding bone was measured., Results: The antibiotic microspheres successfully prevented infection in 100% of the eleven limbs with treated implants, which represented a significant improvement (p = 0.004) compared with the infection rate of 64% (seven of eleven) for the limbs with control implants. Implant integration averaged 38.87% ± 12.69% in the fifteen uninfected limbs, which was significantly better (p = 0.012) than the average of 19.46% ± 14.49% in the seven infected limbs., Conclusions: The antibiotic delivery system successfully prevented infection in 100% of the cases studied, resulting in an increase in implant integration., Clinical Relevance: Antibiotic delivery utilizing the system described here may be effective in preventing implant-associated infections after orthopaedic surgery and increasing the longevity of orthopaedic implants.

Background: The treatment of osteogenesis imperfecta has been directed at improvement of bone mineral density, yet the importance of bone mineral density in predicting functional and clinical outcome in this patient population has not been demonstrated. We used a validated functional outcome measure to identify the relationship between bone mineral density and physical function in children with osteogenesis imperfecta, and we also evaluated the relationship of bone mineral density to the rate of surgery and fracture in patients with osteogenesis imperfecta., Methods: Twenty patients (age range, four to seventeen years) with osteogenesis imperfecta who had undergone bone mineral densitometry as measured by dual x-ray absorptiometry of the lumbar spine, wrist, and proximal aspect of the femur between November 1999 and April 2001 were retrospectively analyzed. Functional outcome was measured with use of the Pediatric Outcomes Data Collection Instrument. These questionnaires were completed by the parents of all twenty patients and, in addition, by fifteen patients in the study who were between the ages of eleven and eighteen years. Fracture and surgery rates were calculated on the basis of the number of documented fractures and surgical procedures that the patient had had from the time of the initial presentation until the time of the latest follow-up visit., Results: There were significant relationships between the bone mineral density of the lumbar spine and the scores obtained on the parent-completed questionnaires with regard to upper-extremity functioning (r = 0.57, p < 0.01), transfers and basic mobility (r = 0.55, p = 0.01), sports and physical functioning (r = 0.55, p = 0.01), and global functioning (r = 0.60, p < 0.004). There were also significant relationships between the bone mineral density of the wrist and the scores obtained on the child-completed questionnaires with regard to upper-extremity functioning (r = 0.82, p < 0.01), sports and physical functioning (r = 0.76, p < 0.01), and global functioning (r = 0.83, p = 0.001). There were significant negative relationships between the bone mineral density of the lumbar spine and the rate of fractures (r = -0.69, p < 0.001) and the bone mineral density of the lumbar spine and the rate of surgery (r = -0.60, p < 0.01)., Conclusions: There is a relationship between bone mineral density and the functional outcome, rate of fracture, and rate of surgery in patients with osteogenesis imperfecta. Bone mineral density appears to be an indicator of disease severity and may be predictive of long-term functional outcome. To establish specific guidelines for treatment, more data on normative bone-mineral density in children with osteogenesis imperfecta will be needed.