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

Abstract

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.

Simultaneous and multisite measure of micromotion, subsidence and gap to evaluate femoral stem stability

“…Subsidence values were also coherent with typical reported data in cadaveric or clinical studies, except for the same case, which explains its high micromotion. From a clinical point of view, the subsidence for the SPS stem of pair #1 was not acceptable, but is however observed in real clinical situations and requires a revision (Flecher et al, 2010). This large subsidence was curtained because of the shape of the medullary canal, not adapted for an anatomical stem.…”

“…Although the survival rate at 15 years of some cementless stems is lower than cemented ones, other cementless designs show equal results (Flecher et al, 2010;Mäkelä et al, 2010;Merle et al, 2010). Failure is mainly associated to aseptic loosening, and has been related, among other problems, to primary stability in animal and human studies (Pilliar et al, 1986;Engh et al, 1992;Bragdon et al, 1996;Jasty et al, 1997).…”

Custom hip arthroplasty

“…With the improvement of the diagnostic and manufacturing protocols, mean implant survival in the first decade is 100% in patients under 65 years with a substantial reduction of the clinical symptoms. Custom stem usage reduces the risk of early aseptic loosening, proximal stress shielding and femoral osteolysis (7,9,15).…”

“…Stability depends on the filling of the proximal femur and the anatomical position of the stem (fit) (7,8). Primary OA and dysplastic hips are correlated with great anatomical variations of the intramedullary canal and femoral neck (anteversion, offset, femoral neck angle) (6,7).…”

“…There are great differences in the tridimensional anatomy of the femoral canal, as well as in the extramedullary parameters, between dysplastic hips and primary OA (7,8). The stage of dysplasia is correlated with the difficulties in the restoration of the acetabular center of rotation, which is necessary for the correct joint kinematics and the lever of the abductor musculature (10,11).…”