title: Failure mechanisms of anatomic porous replacement I cementless total hip replacement.
abstract: The APR-I Hip System was designed for metaphyseal bone attachment by proximal patch porous coating and the acetabular component was a hemisphere fixed with screws. The results of 100 consecutive primary total hip arthroplasties performed with the APR-I were studied in patients still alive after an average of 6.7 years. The selection of hips for implantation of this hip system was limited to those patients in whom a satisfactory intraoperative fit could be obtained. This resulted in a distribution of patients such that 75% were younger than age 65 years and only 15% had osteoporotic bone. The revision rate was 16% with a mechanical failure rate of 11%. Seventy percent of hips had progressive loss of fixation. loss of femoral component fixation was correlated with younger patient age, higher patient activity level, metaphyseal fill of less than 90%, and increased polyethylene wear and osteolysis. Eighty-nine percent of hips maintained femoral neck contact with the porous coated collar. The acetabular component was well fixed in 97% of hips. The failure rate of the APR-I stem is unacceptably high and this stem is no longer used by the authors.
authors.affiliation: USC Center for Arthritis and Joint Implant Surgery, Los Angeles, CA 90033, USA.
authors.forename: L D
authors.initials: LD
authors.lastname: Dorr
authors.forename: K
authors.initials: K
authors.lastname: Lewonowski
authors.forename: M
authors.initials: M
authors.lastname: Lucero
authors.forename: M
authors.initials: M
authors.lastname: Harris
authors.forename: Z
authors.initials: Z
authors.lastname: Wan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016062:Porosity; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D016896:Treatment Outcome