Experimental study about the bony healing of hydroxyapatite coating implants

INTRODUCTION: Hydroxyapatite(HA) coating implant can accelerate osseointegration, however, there are many controversies. MATERIALS AND METHODS: This study examined the early osseointegration of two types of hydroxyapatite coated implants. Twelve adult male miniature pigs (Medi Kinetics Micropigs, Medi Kinetics Co., Ltd., Busan, Korea) were used in this study. In the implants placed in the mandible, a histomorphometric evaluation was performed to evaluate the bone-implant contact (BIC) ratio. RESULTS: The BIC ratio increased with time. TS III HA and Zimmer HA were not significantly different (P>0.05). At 8 weeks, the BIC of Zimmer HA was higher than TS III HA, but there was no significant difference (P>0.05). CONCLUSION: HA coated implants will accelerate early osseointegration.

Early Postoperative Periprosthetic Radiological Findings in Cementless THRA : Comparison between Porous - coated Implant and Hydroxyapatite - coated Implant / 대한정형외과학회잡지

We compared radiologically two groups of total hip prostheses, 36 porous-coated and 51 hydroxyapatite-coated, which had been implanted in 87 hips of 73 patients with avascular necrosis of the femoral head. Radiographs were taken at postoperative 1 year and 2 year, and used to compare various radiological parameters between the two groups. For the acetabular side radioluscent line and osteolysis were evaluated, and for the femoral side radioluscent line, osteolysis, stress shielding. endosteal new bone formation, subsidence and cortical hypertrophy were evaluated; their location was identified according to the zones described by DeLee and Charnley for the acetabulum and according to those described by Gruen et al for the femur. In both groups there was no subsidence. In terms of osteolysis, stress shielding and cortical hyper-trophy there was no significant difference between the two groups throughout the period. Radioluscent line in the acetabulum was more common around the porous-coated cup, but was focal and not progressive. The rate of radioluscent line in the femur was a little higher around hydroxyapatite-coated stem especially in zone 5. Endosteal new bone formation was excellent in both groups, but was more extensive around hydroxyapatite-coated stem. This study suggests that hydroxyapatite coating play a certain role in terms of bony ingrowth.

Teh Effect of Hydroxyapatite Coating on the Mechanical Strengths and Histologic Profiles of Porous Titanium Implants in Dogs / 대한정형외과학회잡지

The purpose of this study is to investigate the effect of plasma sprayed hydroxyapatite(HA) coating on bone ingrowth into fiber-mesh coated titanium implant. The shear strength of the HA coatings on interface attachment, the degree of osseointegration of HA coated implants and bone ingrowth of fiber-mesh coated titanium implants were evaluated. The implants were placed transcortically in the femora of mature dogs and evaluated after six weeks. The pushout test showed 33.58±10.87 MPa in HA-coated fiber meshed implants and 20.53±4.91 MPa in fiber-mesh coated implants. In histologic observations, similar quantitative results in the amount of bone ingrowth and osseointegration on both systems. The HA coatings showed direct osseointegration and bone ingrowth on its surface and fiber-mesh without fibrous layer, but the fiber-mesh only coatings showed thin fibrous layer between the ingrown bone and titanium surface. In conclusion, HA-coating on fiber-mesh coated implant provided earlier and stronger osseointegration and bone ingrowth than fiber-mesh only coated implant.