Promising mid-term results of total hip arthroplasties using an uncemented lateral-flare hip prosthesis: a clinical and radiographic study

Abstract

The clinical results after total hip replacements using noncemented stems have shown considerable variability over the years; the design and characteristics of the implant seemed to play a role in explaining this fact. The purpose of this paper is to report the clinical, radiographic and densitometry results of total hip arthroplasties using a stem designed for noncemented implantation and to engage and load the femur proximally. Fifty-eight consecutive patients (62 hips) followed for an average of 4.3 years (range 36-70 months) were clinically and radiographically followed up at three weeks, three months, six months, one year, and yearly thereafter. The average pre-operative Harris hip score was 49 increasing to 98 at the latest follow-up. There were no cases of aseptic or septic loosening. The average subsidence at three years was 0.45 mm (SD±0.36 mm). Radiographically all hips were classified as stable, and evident changes compatible with new bone apposition were observed in 64% of the cases. The extended proximal geometry of the device seems to favour initial and secondary stability as reflected by the low subsidence values over time. The maintenance of periprosthetic bone stock and the absence of stress shielding can be explained by the predominantly proximal loading pattern of the stem.Résumé Les résultats cliniques des arthroplasties totales de hanche utilisant des tiges non-cimentées ont été très variables au cours des années, les caractéristiques de l'implant semblant jouer un rôle important. Le but de ce travail est de rapporter les résultats cliniques et radiologiques d'arthroplasties avec une tige non-cimentée avec appui proximal. 58 patients consécutifs (62 hanches) suivi en moyenne pendant 4,3 ans (36 à 70 mois) étaient étudiés à 3 semaines, 3 mois, 6 mois, 1 an puis tous les ans. Le score moyen de Harris pré-opératoire était de 49, augmentant à 98 au dernier examen. Il n'y avait pas de descellement aseptique ou septique. L'enfoncement moyen à 3 ans était de 0,45 mm (SD 0,36 mm). Radiologiquement toutes les hanches étaient stables et des modifications compatibles avec une ostéoformation était visible dans 64% des cas. La géométrie proximale de la tige semble favoriser la stabilité initiale et secondaire comme le montre le faible enfoncement au fil du temps. La conservation du stock osseux et l'absence de déviation des contraintes peuvent s'expliquer par la mise en charge proximale de la prothès.

Periprosthetic strain magnitude-dependent upregulation of type I collagen synthesis in human osteoblasts through an ERK1/2 pathway

“…This finding was consistent with a postoperative histological phenomenon that hyperostosis was observed near the tip of stems where postoperative stress distribution markedly increased. Meanwhile, bone loss took place around the proximal part of the femoral prosthesis where stress shielding occurred [20]. The presence of the mechanotransduction threshold in the stretch-induced release of PICP may inversely justify a starting point in postoperative bone loss induced by stress shielding.…”

Metaphyseal‐Loading Anterolaterally‐Flared Femoral Stem in Cementless Total Hip Arthroplasty: Five‐ to Eleven‐Year Follow‐Up Evaluation

“…Kim (24) assessed the outcome of a proximally‐coated anatomic stem (IPS, DePuy, Warsaw, IN, USA) in patients with femoral head osteonecrosis and reported 100% survival rate after a mean 8.8‐year follow‐up for cementless THA. Leali and Fetto (18) also reported a 100% survival rate in 48 patients (62 hips) who underwent cementless THA using a metaphyseal loading lateral‐flared hip prosthesis (Revelation hip stem; Encore, Austin, TX, USA) after a mean follow‐up period of 4.3 years. In our series, one patient underwent revision THA and replacement of a broken ceramic liner, and strictly speaking, this was not a faulty femoral stem but rather a ceramic failure.…”

“…(25) suggested that the femoral stem below the lesser trochanter is not necessary for a cementless anatomical stem with a lateral flare, and stressed that a proximally fitting implant is sufficient. Leali and Fetto (18) indicated that a cementless anatomical femoral stem required a proximal lateral flare to engage the trochanteric area in order to reproduce the compressive forces between the femoral head and greater trochanter. In a series of biomechanical studies that included Japanese patients with dysplastic hip OA but excluded subjects with idiopathic and ethanol‐induced osteopenia, we indicated that the increment of proximal fit‐and‐fill to the intramedullary femoral canal is important for initial stability under force‐loading condition and possible bone ingrowth that contributes to stem longevity (10,13–15).…”

“…Dysplastic hip OA demonstrates a tremendously wide spectrum of morphological deformities in the proximal femur and trochanter (11)(12)(13)17). In cementless THA, many surgeons have attempted to apply plasma-spray coated femoral stems to ensure proximal intramedullary stability as well as potential longevity of the implant with bone ingrowth (2)(3)(4)8,18). Accordingly, in dysplastic hip OA, it is necessary to increase the implant-bone interface within the proximal intramedullary canal, which usually exhibits grossly abnormal configuration (11,13).…”

Tissue differentiation around a short stemmed metaphyseal loading implant employing a modified mechanoregulatory algorithm: A finite element study

“…The lateral flare provides more proximal loading due to the seating of the flare on the lateral cortex of the femur; this feature also provides good stability to the implant and reduces the incidence of migration and subsidence [37][38][39] . This is reflected by the formation of stronger tissues in and around the region.…”