P2 porous titanium implants improve tendon healing in an acute rat supraspinatus repair model.

BACKGROUND: Current techniques in rotator cuff repair often lack structural integrity. P2 porous titanium-coated constructs (DJO Surgical, Austin, TX, USA) promote osseointegration and soft tissue ingrowth. This study examined the ability of this material to improve the structural integrity of supraspinatus tendon repair in a rat model. We hypothesized that P2 implants placed at the tendon-to-bone interface would improve mechanical and histologic measures of supraspinatus healing. METHODS: Forty rats underwent supraspinatus repairs with P2 implants in 1 shoulder and standard repair in the other. Rats were humanely killed at time 0 (n = 3), 2 weeks (n = 8), 4 weeks (n = 15), and 12 weeks (n = 14). Tendon-to-bone composite specimens were harvested and evaluated mechanically and histologically. RESULTS: Tendon cross-sectional area was decreased in the P2 implant group at 4 weeks, percentage of relaxation was increased at 2 weeks, elastic modulus was increased at 4 weeks, and maximum load and maximum stress were both increased at 2 and 4 weeks. Histologic analysis revealed no foreign body reactions within or around the P2 implant, and healthy viable bone was visible within the P2 implant. CONCLUSION: The results support our hypothesis, specifically in early healing, in this randomized controlled animal study. These data support the use of P2 porous titanium implants to improve tendon-to-bone healing.

Does vitamin E-blended UHMWPE prevent biofilm formation?

BACKGROUND: Biofilm-related periprosthetic infections are catastrophic to patients and clinicians. Data suggest the addition of vitamin E to UHMWPE may have the ability to reduce biofilm formation on the surface of UHMWPE; however, previous studies were performed using stagnant broth solutions that may not have simulated a physiologic environment. In addition, the observed differences in levels of bacterial attachment, though statistically significant, may not be clinically significant. QUESTIONS/PURPOSES: We blended vitamin E with UHMWPE material and tested it for the ability to resist biofilm formation using a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). Three additional materials were tested for comparison: highly crosslinked UHMWPE, compression-molded UHMWPE, and polyetheretherketone. We also determined whether the surface roughness of these materials facilitated biofilm formation. METHODS: Using a flow cell system, samples of each material type were placed into separate chambers. A 10% solution of brain-heart infusion broth containing 10(5) colony-forming units (CFUs)/mL was flowed through the flow cell over 48 hours. The number of bacteria that adhered to the surface was quantified and biofilm formation was observed qualitatively using scanning electron microscopy. Optical profilometry was used to determine the surface roughness of each material type. RESULTS: Vitamin E-blended UHMWPE did not reduce biofilm formation of a clinically relevant strain of MRSA compared to materials that did not have vitamin E. More specifically, vitamin E-blended materials had similar amounts of biofilm formation (~ 8 log10 CFUs/cm(2)) compared to materials not containing vitamin E (~ 8.1 log10 CFUs/cm(2)) (p > 0.4). The roughness of vitamin E-blended material surfaces (mean ± SD: 1.85 ± 0.46 µm) compared to that of materials without vitamin E (2.06 ± 1.24 µm) did not appear to influence biofilm formation. CONCLUSIONS: Under physiologically relevant conditions, vitamin E-blended UHMWPE did not have the ability to reduce the formation of biofilms by MRSA. CLINICAL RELEVANCE: These data indicate that the addition of vitamin E to UHMWPE may not reduce clinically relevant rates of biofilm-related periprosthetic infections of total joint arthroplasty devices.