Hyaluronic Acid-Based Hydrogel Coating Does Not Affect Bone Apposition at the Implant Surface in a Rabbit Model.

BACKGROUND: Uncemented orthopaedic implants rely on the bone-implant interface to provide stability, therefore it is essential that a coating does not interfere with the bone-forming processes occurring at the implant interface. In addition, local application of high concentrations of antibiotics for prophylaxis or treatment of infection may be toxic for osteoblasts and could impair bone growth. QUESTIONS/PURPOSES: In this animal study, we investigated the effect of a commercially available hydrogel, either unloaded or loaded with 2% vancomycin. We asked, does unloaded hydrogel or hydrogel with vancomycin (1) interfere with bone apposition and timing of bone deposition near the implant surface; and (2) induce a local or systemic inflammatory reaction as determined by inflammation around the implant and hematologic parameters. METHODS: In 18 New Zealand White rabbits, an uncoated titanium rod (n = 6), a rod coated with unloaded hydrogel (n = 6), or a rod coated with 2% vancomycin-loaded hydrogel (n = 6) was implanted in the intramedullary canal of the left tibia. After 28 days, the bone volume fraction near the implant was measured with microCT analysis, inflammation was semiquantitatively scored on histologic sections, and timing of bone apposition was followed by semiquantitative scoring of fluorochrome incorporation on histologic sections. Two observers, blinded to the treatment, scored the sections and reconciled their scores if there was a disagreement. The hematologic inflammatory reaction was analyzed by measuring total and differential leukocyte counts and erythrocyte sedimentation rates in blood. With group sizes of six animals per group, we had 79% power to detect a difference of 25% in histologic scoring for infection and inflammation. RESULTS: No differences were found in the amount of bone apposition near the implant in the No Gel group (48.65% ± 14.95%) compared with the Gel group (59.97% ± 5.02%; mean difference [MD], 11.32%; 95% CI, -3.89% to 26.53%; p = 0.16) or for the Van2 group (56.12% ± 10.06%; MD, 7.46; 95% CI, -7.75 to 22.67; p = 0.40), with the numbers available. In addition, the scores for timing of bone apposition did not differ between the No Gel group (0.50 ± 0.55) compared with the Gel group (0.33 ± 0.52; MD, -0.17; 95% CI, -0.86 to 0.53; p = 0.78) or the Van2 group (0.83 ± 0.41; MD, 0.33; 95% CI, -0.36 to 1.03; p = 0.42). Furthermore, we detected no differences in the histopathology scores for inflammation in the No Gel group (2.33 ± 1.67) compared with the Gel group (3.17 ± 1.59; MD, 0.83; 95% CI, -0.59 to 2.26; p = 0.31) or to the Van2 group (2.5 ± 1.24; MD, 0.17; 95% CI, -1.26 to 1.59; p = 0.95). Moreover, no differences in total leukocyte count, erythrocyte sedimentation rate, and neutrophil, monocyte, eosinophil, basophil, and lymphocyte counts were present between the No Gel or Van2 groups compared with the Gel control group, with the numbers available. CONCLUSION: The hydrogel coated on titanium implants, unloaded or loaded with 2% vancomycin, had no effect on the volume or timing of bone apposition near the implant, and did not induce an inflammatory reaction in vivo, with the numbers available. CLINICAL RELEVANCE: Antibiotic-loaded hydrogel may prove to be a valuable option to protect orthopaedic implants from bacterial colonization. Future clinical safety studies will need to provide more evidence that this product does not impair bone formation near the implant and prove the safety of this product.

Long-term outcome of multiple joint procedures in haemophilia.

In elderly people with haemophilia (PWH), surgery of more than one joint of the lower extremities might be needed. Multiple joint procedures (MJP) were introduced in 1995, defined as any combination of Total Knee or Total Hip Arthroplasty or Ankle Arthrodesis during one in-hospital stay. The expectation is that by means of such procedures this specific population is able to physically function better for an extended period of time. Thus, they will participate in their society in an optimal way. In this study, we tried to describe an outcome after MJP, including pre- and post-operative pain and range of motion (ROM), and recommend measurement tools. 22 of 37 PWH who underwent MJP between 1995 and 2012 were available for assessment. Pain (WFH score) and range of motion were compared pre and postoperatively. Current outcome was described by VAS per joint, nocturnal and overall pain, MACTAR, Hemophilia Activity List, SF36, and EQ-5D. Mean age at surgery was 50, 3 years (SD 8, 3); mean follow-up 12 years (1-18 years). Pain (VAS) decreased post-surgery (Median 1 - 1, 5), but moderate pain remained. Extension of knees slightly increased, but both knee flexion and ankle plantar and dorsal flexion decreased. PWH reported the ability to stand longer but also pointed at specific problems, e.g. riding a bike (MACTAR). The HAL showed limited activities (functional domains), especially in the 'complex lower extremity' (22, 8/100). The SF36 and EQ-5D showed a mix of physical problems of our population, while experiencing moderate pain and reasonable physical functioning. This led us to the conclusion that adequate follow-up is needed: ROM of all joints, VAS of all joints as well as nocturnal and overall pain, HAL, SF36 and EQ5D. Performance based activities and participation need further attention.

In-hospital rehabilitation after multiple joint procedures of the lower extremities in haemophilia patients: clinical guidelines for physical therapists.

This project aimed to develop guidelines for use during in-hospital rehabilitation after combinations of multiple joint procedures (MJP) of the lower extremities in persons with haemophilia (PWH). MJP are defined as surgical procedures on the ankles, knees and hips, performed in any combination, staged, or during a single session. MJP that we studied included total knee arthroplasty, total hip arthroplasty and ankle arthrodesis. Literature on rheumatoid arthritis demonstrated promising functional results, fewer hospitalization days and days lost from work. However, the complication rate is higher and rehabilitation needs optimal conditions. Since 1995, at the Van Creveldkliniek, 54 PWH have undergone MJP. During the rehabilitation in our hospital performed by experienced physical therapists, regular guidelines seemed useless. Guidelines will guarantee an optimal physical recovery and maximum benefit from this enormous investment. This will lead to an optimal functional capability and optimal quality of life for this elderly group of PWH. There are no existing guidelines for MJP, in haemophilia, revealed through a review of the literature. Therefore, a working group was formed to develop and implement such guidelines and the procedure is explained. The total group of PWH who underwent MJP is described, subdivided into combinations of joints. For these subgroups, the number of days in hospital, complications and profile at discharge, as well as a guideline on the clinical rehabilitation, are given. It contains a general part and a part for each specific subgroup.

Osseointegration of hydroxyapatite-coated and noncoated Ti6Al4V implants in the presence of local infection: a comparative histomorphometrical study in rabbits.

A study was designed to investigate the osseointegration of titanium implants, either noncoated or coated with hydroxyapatite (HA), into rabbit tibiae in the presence of local infection compared with osseointegration in the absence of local infection. HA-coated or noncoated Ti cylinders were implanted into both tibiae of 32 rabbits (New Zealand Whites). Before implantation the left tibia was contaminated with different quantities of Staphylococcus aureus (10(2)-10(5) CFU). Four weeks after surgery the tibiae were explanted and prepared for microbiological and histomorphometrical examination. Histomorphometrical data, as a representation of implant fixation, were obtained by measuring the percentage of bone around the implants (within a radius of 1 mm from the outer diameter of the implants) and the percentage of the circumference of the implant that was in direct contact with bone. Histomorphometry revealed, in particular for the HA implants, a relationship between the inoculum concentration and/or the presence or absence of infection with the bone contact at the distal implant side. This confirms a relationship between peri-implant infection and bone contact or remodeling. HA-coated implants developed, in the presence of bacteria, more easily a more severe infection than noncoated Ti implants, and we show in the present study that local infection will influence histomorphometrical parameters (bone-implant contact) that determine implant fixation. Precautions to prevent contamination (asepsis) and/or infection (perioperative antibiotics) are even more important for the highly biocompatible HA-coated implant.