COMPARISON OF BONE INGROWTH IN NON–HA CUP, HA/TCP SPRAYED CUP, AND ALKALI AND HEAT–TREATED CUP.

Abstract

In this study, bone ingrowth was investigated in three-different cementless acetabular cups, titanium fiber mesh cup (non-HA), hydroxyapatite tricalcium phosphate sprayed cup (HA/TCP), alkali- and heat-treated titanium porous cup (AH). “Gap filling” was evaluated as the finding of the bone ingrowth on X-ray. The phenomenon is that slight gap between acetabulum and the cup observed after total hip arthroplasty (THA) disappear gradually.

One hundred and thirty-seven consecutive primary THAs using cementless cups were evaluated for the rate of bone ingrowth. Patients were divided into three groups based on the different types of cups, 51 non-HA cups, 51 HA/TCP cups and 35 AH cups. The groups were similar with regards to age, sex, body mass index, original diagnosis, surgical technique and post operative rehabilitation. Average follow up period was35months, 33 month and 32 months respectively.

Initial gap between acetabulum and the cup after operation was observed in 44 hips of non HA group, 39 hips of HA/TCP group and 33 hips of AH group. Rate of the gap filling at the last follow up was 2 hips (4.5%) in non-HA, 31 hips (79.5%) in HA/TCP and 33 hips (100%) in AH. Early gap filling that occurred for less than three months was 17.9% (7 of 39) in HA/TCP and 72.7% (24 of 33) in AH.

The HA/TCP coated cup and the alkali- and heat-treated cup had the high frequency which gap filling occurred compared with the cup of only titanium fiber mesh processing. Additionally, in the AH cup more gap filling for less than three months had occurred compared with the HA/TCP cup, so AH cup is the most effective implant to obtain the bone ingrowth at an early stage and it is expected to acquire the better results.