Excellent midterm survival and functional outcomes of a fully hydroxyapatite-coated cementless stem: first results of a prospective multicenter study

Abstract

Background: The Polarstem (Smith & Nephew, Baar, Switzerland) is a tapered straight stem, an implant with an excellent survival rate. Although the most recent annual report of the National Joint Registry in the United Kingdom also reports excellent survivorship for the cementless Polarstem, no prospective studies have been published focusing on both its efficacy and clinical performance. Therefore, the present study was designed to prospectively evaluate its functional and radiographic outcomes at midterm. Methods: This prospective observational study conducted at 3 independent orthopaedic hospitals was designed to collect data in patients undergoing cementless primary total hip arthroplasty (THA). A total of 225 total hip arthroplasties (75 at each site) were performed. The predominant diagnosis was primary osteoarthritis. Anteroposterior and lateral radiographs were obtained at each follow-up (3 months, and 1, 3, and 5 years). Survivorship and the Harris Hip Score (HHS) and Western Ontario and McMaster Universities Index (WOMAC) were calculated. Results: Subjects experienced statistically significant improvements from baseline in mean HHS (48.5 to 88.0, P < .01) and WOMAC scores (58.6 to 9.3, P < .01) at all intervals through 5 years. The stem survivorship was 99.6% at 5 years with stem revision due to any reason. There were no observed cases of mechanical failure of the stem or signs of radiographic loosening. Conclusions: A revision rate of the femoral stem for any reason of 0.4%, as well as good clinical results based on HHS and WOMAC scores, was noted at 5-year follow-up. Therefore, safety and efficacy of the cementless Polarstem at midterm follow-up is confirmed.

New Evaluation Method for Bone Formation around a Fully Hydroxyapatite-Coated Stem Using Digital Tomosynthesis: A Retrospective Cross-Sectional Study

“…The long-term revision rate of the POLARSTEM is lower than that of other cementless stems, and the results have been reported to be good [5]. Good midterm results at 7 y postoperatively and long-term results at 11 y postoperatively have also been reported [27][28][29]. The SBF observed using DTS in the present study may reflect the effect of the HA coating and may contribute to the good long-term results of the POLARSTEM.…”

Effect of femoral stem surface coating on clinical and radiographic outcomes of cementless primary total hip arthroplasty: a patient-matched retrospective study

“…Many studies have reported on outcomes of HA-coated stems [1,8,9,28,29], but only a few have reported on outcomes of other coatings. Studies on stems with first plasma-sprayed titanium and then HA coating have reported satisfactory mid-and long-term outcomes [6,[30][31][32], this coating combination may provide stronger biological and mechanical bone fixation compared to only HA coating [6,33,34]. A recent study by Liu et al [35] has shown that a pore size between 50 and 800 μm stimulates bone ingrowth.…”

Use of a Plasma-Sprayed Titanium-Hydroxyapatite Femoral Stem in Hip Arthroplasty in Patients Older than 70 Years. Is Cementless Fixation a Reliable Option in the Elderly?

“…Moreover, the first porous Ti coating, together with the external layer of HA, showed a synergic combination promoting fast implant osseointegration and stronger mechanical fixation with bone [ 29 ]. Some recent studies have reported excellent mid- to long-term stem survivals with the Polarstem, a Corail-design plasma-sprayed stem with 180 μm porous Ti and 50 μm HA, suggesting that this type of double Ti/HA plasma-sprayed coating could massively reduce the risk of implant aseptic loosening [ 30 , 31 , 32 ].…”