Long-Term Results of Total Hip Arthroplasty

Cemented Fixation

Use of cemented acetabular component fixation varies throughout the world. Despite decreased use in the United States, cemented acetabular components continue to be an important surgical technique in THA. In 2015, the Norwegian Arthroplasty Register demonstrated use of cemented acetabular components in 40% of THAs. In the Australian National Joint Replacement Registry, cemented cups were used in only 10% of THA cases in 2015. Historically, cemented all-polyethylene acetabular components have been regarded by some as the gold standard. Multiple reports confirm survival of 85% to 92% after 16 to 25 years and revision rates of 2% to 17% after 17 to 30 years when aseptic loosening is the endpoint.

Proponents of cemented acetabular components report lower cost, lower polyethylene wear rates versus early modular cementless components, and the potential for excellent long-term survival rates. Additionally, all-polyethylene components offer increased polyethylene thickness versus cementless metal-backed designs. In special conditions such as developmental dysplasia of the hip, in which miniature acetabular components may be required, this increased polyethylene thickness can reduce polyethylene stresses and potentially enhance wear.

De Jong et al. evaluated 287 THAs using an all-polyethylene hemispherical Weber acetabular component (Allopro, Baar, Switzerland) with a modified technique for cementing and a cemented femoral component. The modified technique for acetabular preparation involved reaming only to the subchondral plate, followed by impaction of the bone in the anchorage holes. They found that the survival rate, with acetabular revision for aseptic loosening as the endpoint, was 99.1% (95% confidence interval [CI] 97.9–100) at 10 years and 85.5% (95% CI 74.7–96.2) at 20 years. Apart from contributing to long-lasting fixation of the component, they noted preservation of the acetabular bone that could facilitate revision when necessary. Lewthwaite et al. reviewed survival rates and the clinical and radiographic outcomes of the Exeter Universal hip (Stryker Inc., Newbury, UK) implanted in 107 patients (130 hips) 50 years old or younger at the time of operation. Survival rates of both the femoral and acetabular components from any cause was 92.6% at an average of 12.5 years. They felt that this device performed well, even in the young, high-demand patient.

Cemented techniques can also be effective in special situations, such as patients with severe acetabular dysplasia and patients younger than 40 years. Busch et al. reported that the survival rate for all-cause revision was 98% (95% CI 92.5%–100%) in a series of cemented sockets with an associated roof bone graft used in cases with severe acetabular dysplasia at a mean follow-up duration of more than 10 years. De Kam et al. prospectively followed 130 patients with 175 cemented acetabular components in patients younger than 40 years and found that the 10-year survival rate of cemented acetabular components, with an endpoint of revision for any cause, was 85%.

Detractors of cemented acetabular component fixation cite increased acetabular loosening rates over time, especially in younger subjects. Numerous reports have demonstrated inferior results compared with those previously discussed. Buckwalter et al. reviewed a prospective, single-surgeon series of 357 hips (320 patients) treated with a primary Charnley THA with contemporary femoral and acetabular cementing techniques. Of the 32 hips followed for over 25 years, 9 acetabular components (28%) were revised for aseptic loosening in addition to 5 acetabular components (16%) with radiographic evidence of loosening that had not yet been revised. Mulroy and Harris reported on acetabular and femoral fixation in 47 hips followed for 15 years after cemented THA. Ten acetabular components (21.3%) required revision for aseptic loosening. Ballard et al. found progressive problems with fixation of the acetabular component despite the use of improved cementing techniques in 42 primary cemented THAs followed for an average of 11 years. They reported that 10 acetabular components (28%) had to be revised for aseptic loosening. Hirose et al. noted mechanical failure in 21 of 114 acetabular components (18.4%) with a minimum of only 5 years’ follow-up duration. Smith et al. noted that 32 of 84 cemented acetabular components (49%) had been revised because of loosening or were radiographically loose but had not yet been revised at a mean of 18 years following the THA.

Chen et al. evaluated the clinical and radiographic results of 86 primary THAs with a cemented metal-backed acetabular component and a cemented collared straight femoral stem. Seven patients (9.2%) underwent acetabular component revision at a mean of 9.0 years after implantation and an additional 24 components (31.6%) demonstrated evidence of radiographic loosening, resulting in a total failure rate of 40.8%. They felt that the significant overall rates of radiographic loosening, migration, polyethylene wear, and implant revision confirmed the suspected trend of increasing failure rate of cemented metal-backed acetabular components over time.

The variable results of cemented acetabular fixation suggest that surgical technique plays an important role in long-term survival. Crites et al. evaluated the effect of porosity reduction cementing techniques in 2237 consecutive cemented acetabular components performed between 1970 and 1998. They found that essential cementing techniques included reaming through dense subchondral bone to achieve a good cancellous bone bed, perforation and removal of peripheral sclerotic areas, cementing into a dry cancellous bone bed, pressurization of the entire cement mantle in the socket at one time, and complete burying of the acetabular component within the boundary of the bony acetabulum. They also believed that bone quality played a significant role in acetabular fixation. Ranawat et al. concluded that most mechanical failures of cemented socket fixation within 10 years of primary operation were attributable to failure to achieve a good fixation initially of the cement and bone. To optimize successful initial fixation with cement, they recommended hypotensive epidural anesthesia to assist in obtaining a dry bone bed. Multiple 5-mm-diameter countersink anchorage holes can also help in initial stability. Mootanah et al. proposed that the longevity of cemented total hip replacements could be improved by drilling a few large anchorage holes.