The Journal of Bone and Joint Surgery, Vol. 72-B, pp. 2-8, 1990
Author: Ray J. Haddad, MD, Stephen D. Cook, MD, Mark R. Brinker, MD
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Aseptic loosening is the most common mode of failure of cemented total joint replacements. Various factors including patient selection, implant design and cementing technique have been implicated in the failures (Stauffer 1982; Dorr, Takei and Conaty 1983; Johnston and Crowninshield 1983). The increased use of hip replacement in younger, more active patients has led to the development of porous-coated devices intended for fixation by bone ingrowth. Extensive bone ingrowth has been demonstrated in numerous animal studies (Galante' et al 1971; Cameron, PlIliar and Macnab 1973, 1916; Ducheyne, De Meester and Aernoudt 1977; Bobyn cl al 1980; Clemow et al 1981; Harris et at 1983; Hedley et al 1983; Cook, Walsh and Haddad 1985) but only limited bone ingrowth with abundant fibrous tissue has been reported in human retrieval studies (Bobyn and Engh 1984; Brookerand Collier 1984; Cameron 1986; Cook et a11986; Ranawatetall986; Engh, Bobynand Glassman 1987; Collier et al 1988; Cook, Thomas and Haddad 1988; Cook et aI 1988a).
Early clinical results with noncemented joint replacements have been promising (Eogh 1983; Hungerford and Kenna 1983; Dore 1986; Landon. Galante and Maley 1986; Hedley et al 1987; Laskin 1988). but some recent studies have suggested that cemented implants perform significantly better (Harris and McGann 1986; Alani et at 1988; Petty, Fajgenbaum and Bush 1988; Rorabeck, Bourne and Nott 1988; Russotti, Coventry and Stauffer 1988). Of particular concern is the troubling incidence of persistent pain reported in many studies of uncemented implants (Engn et at 1987; Callaghan. Dysart and Savory 1988; Petlyet a11988; Rorabeck et al
1988). This is generally attributed to poor initial fit and instability as well as mechanical factors such as stress shielding and altered stress transfer. A number of porous· coated total hip systems have become available.
Our study reports the results of a clinical and radiographic comparison of three noncemented porouscoated total hip designs in 134 primary arthroplasties. The first prosthesis was the DePuy AML (Anatomic Medullary Locking; DePuy Inc, Warsaw, Ind, USA) which consists of a straight femoral stem with a collar and a hemispherical acetabular cup with three spikes, all porous-coated (Fig. I). The second prosthesis was the Howmedica PCA (Porous Coated Anatomic; Howmedica Inc, Rutherford NJ, USA); this has an anatomically shaped collarless femoral stem and a hemispherical acetabular cup with two fixation pegs (Fig. 2). The third was the Implant Technology LSF (Long-Term Stable Fixation; Implant Technology Inc. Secaucus, NJ, USA) which consists of an anatomically shaped femoral stem.
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