Polyethylene wear, osteolysis and acetabular loosening with an HA-coated hip prosthesis

Abstract

We have followed up for a period of seven to nine years 100 consecutive arthroplasties of the hip in which an entirely HA-coated implant had been used. The clinical results were excellent and bony incorporation was extensive in all components. No stem became loose or subsided but five cups were revised because of loosening after 3.8 to 5.5 years, having functioned painlessly and shown radiological ingrowth. Revision procedures because of excessive polyethylene wear have been performed on 18 hips and are planned for six more. Two eroded metal backings with worn-through polyethylene were exchanged; six hips showed metallosis without polyethylene wear-through. There were two cases of granulomatous cysts in the groin and 66 hips had osteolysis located periarticularly, in the greater trochanter or in the acetabulum.

Inferior Survival of Hydroxyapatite versus Titanium-coated Cups at 15 Years

“…The higher variation of femoral head penetration in the HA group as opposed to the Ti group (SD 0.26 mm/year and 0.14 mm/year, respectively) supports the concerns expressed in other studies with individual cases of high PE wear with HA-coated cups leading to implant failure [7,8,11,21,29,42]. The cases of high PE wear in our study could be related to HA particles separating from the coating leading to increased backside wear and articulate wear on the PE, a mechanism described by Bauer, Morscher et al, and Rokkum et al [4,33,43].…”

“…Numerous authors have described a larger main group of well-performing cups with a smaller group of cup failures attributable to osteolysis, wear, aseptic loosening, and PE fracture (Table 3). Apparently, there is no clear association between worn failing implants and the clinical performance [29,33], and thus expansile (cystic) osteolysis and loosening may progress without warning signs [5,33,42].…”

“…Disintegration of the HA coating is influenced by numerous factors, including the purity of HA, manufacturing, crystallinity, porosity, method of coating, the thickness of the HA coating, the surface on which HA is deposited (smooth or rough), the adhesive strength of HA to the substrate [33], and the speed of resorption [8,35,45]. Calcium phosphate coatings have been applied plasma-sprayed with different quality and coating thicknesses ranging from 300 lm [33,43], over 150 lm [42], to 40 lm [41]. Thinner plasma-sprayed HA coatings (50 lm) have been recommended, as they give a stronger fixation and reduce the risk of HA fracture [44].…”

“…For some cups, there is a plausible explanation of failure, eg, in cases of HA coating applied to smooth surfaces [13,29,42], very thick coatings [33,42], the presence of screw holes [7,25], a poor locking mechanism [32], and conventional PE. However, for other HA-coated cup designs, the reasons for the wear rate, osteolysis, and revision are not entirely transparent [7,21,25,34] and raise concern regarding continued use of HA coating for acetabular cups.…”

High osteolysis and revision rate with the hydroxyapatite-coated ABG hip prostheses65 hips in 56 young patients followed for 5–9 years

“…These observations emphasize the importance of regular radiographic follow-up, especially where previous long-term results are missing and the group of patients is young. Rokkum et al (1999) presented a 78% survival rate for the polyethylene inlay in an HA-coated threaded cup after 8 years. There were no stem revisions.…”