Seven to 10 Years Followup of an Anatomic Hip Prosthesis

Abstract

Hypothetically, hydroxyapatite-coated anatomic-shaped femoral stems and hemispheric acetabular cups should improve biologic fixation of the implant and strength transmission to the bone, improving unsatisfactory results of the first cementless hip prosthesis focused on the stress-shielding phenomenon at the femur and failure of the threaded acetabular cups. A consecutive series of 312 patients who had primary Anatomique Benoist Giraud hip prostheses unilaterally implanted were followed up. We analyzed the clinical and radiographic results and report the outcomes 7-10 years after implantation. Two hundred thirty-two patients were assessed at 7-10 years. The survival rate for the implant was 96.8%; 77.2% of patients had no pain, 72.4% maintained total mobility, and 62.9% were able to walk without restrictions. However, radiologic assessment shows that problems improved but did not disappear. More than 55% of femurs had signs of proximal stress-shielding develop. More important, substantial polyethylene wear was observed in at least 62% of the acetabular inserts at 7-10 years followup.Cemented hip prostheses have been implanted with satisfying results since the 1960s. 7,8 However, the relatively frequent onset of pain and disability, secondary to loosening at the prosthesis-cement or cement-bone interfaces 26,28,36 has impaired long-term outcomes, particularly in young patients.The first cementless designs, characterized by straight and very stiff distally fixed cementless stems, had serious stress-shielding phenomenons. 30,34 Threaded acetabular cups also failed after 4-5 years. 30,34 To avoid these problems new fixation systems were developed, 15,16 and new models were designed. New hemispheric press-fit acetabular cups and new anatomic-shaped femoral stems transmitted load in the metaphyseal area, theoretically reducing the stress-shielding effect. However, this effect did not disappear, although it became weaker. 20,44 A new step to improve proximal fixation of the femoral stem consisted of using HA coating on its metaphyseal part to facilitate bone ongrowth. 1,19,21 Another problem detected in cemented prostheses was the appearance of osteolysis secondary to inflammatory reactions against polyethylene (PE) and cement particles. 29,36 The problem of osteolysis has not disappeared with new cementless implants, 37 although now its origin is PE wear. This probably is the most serious threat to implant survival according to Harris who stated, "the problem is osteolysis". 23 A prospective international study evaluated the midterm followup results of an anatomic proximal hydroxyapatite (HA)-coated stem and hemispheric HA-coated cup hip prosthesis. The aim of the study was to monitor the clinical and radiographic outcome of patients implanted with the ABG system. The early, 2-year, and 5-year results have been published, 48,49 and the 7-to 10-year results are presented here. Although HA-coated implants have been investigated for more than a decade, only a few midterm results are published. 4,14 At first, our hypothesis...

Poor Survival of Abg I Hip Prosthesis in Younger Patients

“…Indeed, Oosterbos et al found signifi cantly better survival for ABG I prosthesis in patients with a mean age of 72 years when the youngest was 55 years old 15 . In contrast, others 17,21 used the same prosthesis in a wider spectrum of patients including those younger than 60 years and found much better survival than in the current study suggesting the reasons for observed diff erences might be more complex. Primary diagnosis is another factor that could infl uence the prosthetic survival (Tables 5a, b).…”

“…International multi-centre prospectively designed studies were performed in the case of ABG I 4,15,21 . However, none of these revealed any design or material weaknesses in the ABG I prosthesis on time.…”

Ten-year follow-up of an anatomical hydroxyapatite-coated total hip prosthesis

“…Radiographically, as with other authors using this implant [9] we did not observe acetabular cup migration. We think that porous coating improves the interlocking by acetabular bone [4] and that HA coating accelerates bone growth through the micro-porous surface and improves contact [22] between host bone and implant, avoiding migration.…”

“…Frictional heating of PE cups articulated with zirconia heads has been previously reported as responsible for accelerated PE wear [13]. In any case, two issues may be decisive in the origin and evolution of this problem: (1) all our patients were implanted with a hooded PE insert that facilitates the repetitive contact between the stem neck and the prominent PE; (2) this contact can be responsible for a dragging movement of the femoral head over the interior surface of the insert [9]. Both of these factors accelerate PE wear.…”

Cross-linked Compared with Historical Polyethylene in THA: An 8-year Clinical Study

“…Cysts suggesting wear debris-driven osteolysis reportedly occur more frequently on the acetabulum than the femur [23]. This can be expected because the acetabular bone-implant interface is closer to the origin of wear debris and because the interface between the proximal femur and hydroxyapatite-coated stem probably is better sealed against particle migration [40].…”