The Influence of Stem Size and Extent of Porous Coating on Femoral Bone Resorption after Primary Cementless Hip Arthroplasty

There are two broad-based categories of cementless femoral component designs: proximally porouscoated and fully porous-coated. While both have been widely used, there remains debate regarding differences in clinical outcome scores, relative incidence of thigh pain, and development of stress shielding. We investigated these variables in a multicenter prospective randomized blinded clinical trial of 388 patients from three centers: 198 patients had a proximally porous-coated tapered cementless femoral component and 190 patients had a fully porous-coated cementless femoral component. A minimum followup of 2 years (mean, 6.7 years; range, 2.0-8.65 years) was available in 367 of the 388 patients (95%).

Section: Discussionmentioning

confidence: 83%

Proximally Versus Fully Porous-coated Femoral Stems: A Multicenter Randomized Trial

MacDonald

Rosenzweig

Guerin

et al. 2010

“…We recorded progressive radiolucencies, radiolucencies greater than 2 mm in width, and the presence of osteolysis. The femoral component stability was evaluated according to the criteria of Engh and Bobyn [21]. We considered a stem loose if subsidence was greater than 2 mm or if the angular position of the stem shifted more than 2°.…”

Section: Methodsmentioning

confidence: 99%

Custom Cementless Stem Improves Hip Function in Young Patients at 15-year Followup

Flécher

Pearce

Parratte

et al. 2010

THA in young patients is challenging regarding restoration and survival because patients are young, active, and tend to have disturbed anatomy. We asked whether a three-dimensional custom cementless stem could restore hip function, decrease osteolysis and wear, and enhance stem survival in young patients. We retrospectively reviewed 212 patients (233 hips) younger than 50 years (mean, 40 years) at a followup of 5 to 16 years (mean, 10 years). The Merle D'Aubigné-Postel and Harris hip scores improved at last followup. No thigh pain was recorded for any of the patients; 187 of the 212 patients (88%) had full activity recovery, 206 had full range of motion, and 151 had a score greater than 80 points for all five categories of the Hip disability and Osteoarthritis Outcome score. Five patients had femoral osteolysis not associated with pain. With revision for any reason as an end point, the survivorship was 87% (range, 77%-97%) at 15 years, and considering stem revision only, the survivorship was 93% (confidence interval, 90%-97%) at 15 years. Our data compare favorably with those from series using standard cementless stems at the same followup with a high percentage of patients achieving functional restoration and a low rate of complications.

“…Augmented bone ongrowth has been documented as early as 3 weeks and as persisting for some years [2-4, 11, 26, 27]. However, as much as 20% to 30% of bone loss at the proximal femur has been reported after THA for the same period as a consequence of proximal stress shielding [8,21,30]. It also is expected and observed that the HA coating resorbs with time [1-3, 18, 19, 27, 28], although it is unknown whether this adversely influences the amount of long-term bone ongrowth.…”

Section: Introductionmentioning

confidence: 99%

Bone Remodeling and Hydroxyapatite Resorption in Coated Primary Hip Prostheses

Tonino¹,

Wal²,

Heyligers³

et al. 2009

Hydroxyapatite coatings for THA promote bone ongrowth, but bone and coating are exposed to stress shielding-driven osteoclastic resorption. We asked: (1) if the resorption of hydroxyapatite coating and bone ongrowth correlated with demographics; (2) if the resorption related to the stem level; and (3) what happens to the implant-bone interface when all hydroxyapatite coating is resorbed? We recovered 13 femoral components from cadaveric specimens 3.3 to 11.2 years after uneventful primary THA. Three cross sections (proximal, medial, distal) of the hydroxyapatite-coated proximal implant sleeve were analyzed by measuring the percentage of residual hydroxyapatite and bone ongrowth on the implant perimeter. Hydroxyapatite resorption was independent of patient age but increased with time in vivo and mostly was gone after 8 years. Bone ongrowth was independent of time in vivo but decreased with aging patients. Only in the most proximal section did less residual hydroxyapatite correlate with less bone ongrowth. Hydroxyapatite resorption, which was more proximal than distal, showed no adverse effects on the implant-bone interface.