title: Dislocation rate after hip arthroplasty within the first postoperative year: 36 mm versus 28 mm femoral heads.
abstract: Dislocation is a common and important complication of total hip arthroplasty (THA). Larger femoral heads may reduce the risk of dislocation and improve the range of movement. The aim of this study was to compare the relative risk (RR) of dislocation during the first year after THA between implants with 28 mm and 36 mm femoral heads. 198 consecutive hips with 28 mm femoral head (Group-28) and 259 hips with 36 mm femoral head (Group-36) were studied. The patients were assessed preoperatively and periodically using the Harris hip score (HHS) and radiographic analysis. The relative risk (RR) of dislocation was calculated. The average HHS significantly improved from a preoperative baseline to the last follow-up at 82.1 months (28 mm) and 44.3 months (36 mm). No statistically significant differences were revealed between the two groups for HHS results and complications (p>0.05), but the difference in RR of dislocation within the first year between the two groups was 7.85 (95% CI: 1.34-46.03), p=0.046.Although dislocation is multifactorial in etiology, the two groups were homogenous for all principal contributing factors except the diameter of the femoral head. Therefore, the use of 36-mm heads can reduce the risk of dislocation following THA by a factor of 8 compared to conventional 28 mm heads.
authors.affiliation: Department of Orthopaedics and Traumatology, CTO Hospital, Turin, Italy. alessandro.bistolfi@cto.to.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bistolfi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Crova
authors.forename: Federica
authors.initials: F
authors.lastname: Rosso
authors.forename: Paolo
authors.initials: P
authors.lastname: Titolo
authors.forename: Stefano
authors.initials: S
authors.lastname: Ventura
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Massazza
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005270:Femur Head / Q000473:pathology; D006304:Health Status; D006617:Hip Dislocation / Q000453:epidemiology* / Q000209:etiology / Q000534:rehabilitation; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000209:etiology*; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D013997:Time Factors