Abstract
The RIPO register collects data of all primary and revision hip replacement surgeries performed in Region Emilia-Romagna, Italy since 1stJanuary 2000.
The present study is aimed to analyze the survival rate of patients with Biolox®delta and Biolox®forte components, (CeramTec, Plochingen Germany) considering possible confounding factors. Only patients living in the region are considered in analysis, to avoid the bias resulting from the ‘loss’ of non-resident patients. The analysis has been conducted only on uncemented THA and monoblock, double mobility cups as well as such with pre-assembled inserts were excluded. Therefore, the finally analyzed database consists of 30’617 cases; 13’323 Biolox®forte and 17’294 Biolox®delta heads, articulating against ceramic or PE.
Unadjusted survival analysis was calculated according to Kaplan Meier method; with prosthesis failure as end point, defined as the revision of any prosthetic component for any cause.
To avoid a possible bias, revision of the prosthesis due to breakage of modular necks of the stem have not been considered. The results are summarized in Table 1.
*survival at 6 yrs follow-up
After adjusting for age and gender it resulted that Biolox®delta - XLpoly and Biolox®forte – poly increase the risk of revision (HR 1.4 and 1.2) compared to Biolox®delta - Biolox®delta;
When only ceramic fractures are considered, we observed 1 fracture of a 36 mm Delta head (1/8’917 = 0.01%) and 38 fractures of 28 mm Forte heads. The 38 fractures occurred mainly in cer-cer coupling (35/3’537 implants= 1%) and occasionally in cer-poly couplings (3/4’246 implants = 0.07%).
Fracture or damage of the Biolox®delta insert occurred in 10 implants out of 14’260(0.07%), while it had a higher incidence in Forte inserts (36 casesout of 6’932 implants = 0.52%).
It can be concluded that the presence of a poly liner decrease the survival of the implant. Beside this Biolox®delta significantly improved the resistance to fracture of both head and insert.
Acknowledgements
This work was partially supported by Italian Ministry of Health, Grant ‘Early diagnosis of pending failure.’ and by Regione Emilia Romagna, cofounding of RIPO. All orthopedic Units of the Region are gratefully acknowledged for providing data to the Register
