title: The effect of the offset humeral head on the micromovement of pegged glenoid components: a comparative study using radiostereometric analysis.
abstract: In a prospective study between 2000 and 2005, 22 patients with primary osteoarthritis of the shoulder had a total shoulder arthroplasty with a standard five-pegged glenoid component, 12 with non-offset humeral head and ten with offset humeral head components. Over a period of 24 months the relative movement of the glenoid component with respect to the scapula was measured using radiostereometric analysis. Nine glenoids needed reaming for erosion. There was a significant increase in rotation about all three axes with time (p < 0.001), the largest occurring about the longitudinal axis (anteversion-retroversion), with mean values of 3.8 degrees and 1.9 degrees for the non-offset and offset humeral head eroded subgroups, respectively. There was also a significant difference in rotation about the anteversion-retroversion axis (p = 0.01) and the varus-valgus (p < 0.001) z-axis between the two groups. The offset humeral head group reached a plateau at early follow-up with rotation about the z-axis, whereas the mean of the non-offset humeral head group at 24 months was three times greater than that of the offset group accounting for the highly significant difference between them.
authors.affiliation: Hand and Upper Limb Research Unit, Wrightington Hospital, Wigan, UK. uplimb_dn@hotmail.com
authors.forename: D
authors.initials: D
authors.lastname: Nuttall
authors.forename: J F
authors.initials: JF
authors.lastname: Haines
authors.forename: I A
authors.initials: IA
authors.lastname: Trail
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000379:methods; D002484:Cementation / Q000379:methods; D005260:Female; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000503:physiopathology / Q000601:surgery*; D025341:Principal Component Analysis; D011446:Prospective Studies; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology; D012785:Shoulder Joint / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome