title: Follow-up results of 10-12 years after total hip arthroplasty using cementless tapered stem -- frequency of severe stress shielding with synergy stem in Japanese patients.
abstract: Synergy stems are tapered stems featuring a proximal porous coating, grid blasting below the proximal third to the distal end. This study included 41 patients (50 hips) who underwent total hip arthroplasty with follow-ups for 10 years or more. No stem reimplantations were performed. Spot welds were observed in the distal stem in Gruen zones 3 and 5 in 35 and 32 hips, respectively. First-degree stress shielding occurred in 8 hips; 2nd-degree, 20 hips; 3rd-degree, 13 hips; and 4th-degree, 9 hips. Because of bone fixation to the distal grit-blasted section of the stem, severe stress shielding was observed in nearly half of the cases. Multiple regression analysis of stress shielding determinants revealed a correlation between stem size and short patient height, showing the cause of stress shielding to be a mismatch in size between the stem and the femoral bone.
authors.affiliation: Department of Orthopaedic Surgery, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Nishino
authors.forename: Hajime
authors.initials: H
authors.lastname: Mishima
authors.forename: Haruo
authors.initials: H
authors.lastname: Kawamura
authors.forename: Yukiyo
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Syumpei
authors.initials: S
authors.lastname: Miyakawa
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ochiai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015519:Bone Density; D001862:Bone Resorption / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007564:Japan; D007592:Joint Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011859:Radiography; D016896:Treatment Outcome
keywords: distal fixation; stress shielding; tapered stem; total hip arthroplasty