Authors: Jarbo K, Overstreet D, McLaren A, Dovigi A, Vernon B, McLemore R.
Banner Good Samaritan Medical Center, Phoenix, AZ and Arizona State University, Tempe, AZ
Title: Bone Healing is Unaffected by PNDJ Hydrogel At Bone-Implant Interface.
Background: A promising approach for preventing infections on cementless implants is to use resorbable in situ forming hydrogels to deliver antibiotics. Previous research found that PNDJ hydrogel is capable of controlled antibiotic release while not being cytotoxic to fibroblasts and osteoblasts. It has additionally been shown that osteoblasts will successfully mineralize in vitro in the presence of high concentrations of polymer degradation byproducts. The effect of the polymer and its degradation byproducts on implant incorporation has yet to be studied.
Hypothesis/Purpose: Does the presence of PNDJ hydrogel alter healing at the implant-host interface?
Methods: 16 trans cortical sites,8 distal femur, 8 proximal tibia, in 4 NZW rabbits distal femurs and proximal tibias were implanted with custom trans cortical titanium implants. Sites were block randomized to either PNDJ Hydrogel or saline control to coat the implant surface and filled the recipient site prior to implantation. Soft tissues and skin closed over the site. Implanted bone segments and overlying soft tissue were harvested at 8 weeks, examined using hard tissue histology.
Results: All tissues and implant-host interfaces were histologically normal with at most a single layer of fibrocytes at the interface. There were no findings suggestive of tissue necrosis or acute or chronic inflammatory process.in any of the samples. Bone formation was seen up to the surface of the implant in all groups (Fig 1). There was no evidence of polymer present in any section.
Discussion: PNDJ hydrogel has been shown to be an effective antimicrobial delivery vehicle with potential use for prophylaxis in uncemented implants. These studies show that the polymer and its degradation byproducts do not alter local healing response, initiate a local reactive process or limit bone apposition to a surface of an implant, all critical to successful clinical application.
Conclusion: PNDJ hydrogel does not affect healing at or near the implant-host interface in rabbits.