[Clinical analysis and prevention from coating shedding of uncemented hip prosthesis]

The long-term biological effects of HA-coated prostheses remain uncertain. The purpose of the study is to analyze the reasons of coating shedding of uncemented hip prothesis, so as to provide evidences for the preventions and treatment.

From 2002.10 to 2009.2, 5 patients with coating shedding of uncemented hip prosthesis were treated with kip revision operation. Among the patients, 3 patients were male and 2 patients were female, ranging in age from 55 to 68 years. The hip prosthesis were taken out in the operation and the cause of coating shedding was analyzed. Another ten normal prosthesis taken out from the revision operation were used as the control group. The histomorphology and microarchitecture of hip prosthesis were observed. The micrometer caliper and vickers hardness test were used to measure the thickness and hardness. The interface shearing force was measured by push-out test. The function of hip joint was evaluated by Harris score.

There were difference between control and experience groups in his tomorphology observation. In the 2 patients with HA-coated shedding, the thickness of coating were 112 microm and 138 microm respectively; Vickers hardness were 5,843 Hv and 4,524 Hv respectively; and the shear strength were 12.4 MPa and 11.6 MPa respectively. In the 3 patients with Ti-coated shedding, the Harris scores were 82, 88 and 87 respectively.

There are many reasons of coating shedding of uncemented hip prosthesis. But most reasons have relationship with the quality of hip prosthesis. Nowadays, there are many methods to enhance the binding strength between the coating and prosthesis, and to prevent the early coating shedding.