title: Four-year results of Summit stems for total hip arthroplasty in Japanese patients.
abstract: OBJECTIVE
  A retrospective study to evaluate the clinical and radiographic outcome of the Summit primary total hip arthroplasty (THA) at a minimum follow-up of 4 years.
  
  
  METHODS
  87 hips in 84 Japanese patients underwent THA using Summit stems. 3 patients were lost to follow-up, and 4 patients were excluded because a Summit stem was judged to be inappropriate for their narrow femoral canals. The remaining 80 hips in 77 patients were evaluated. Mean age was 66 years (range, 33-86 y). Mean postoperative follow-up period was 52 months (range, 48-66 m).
  
  
  RESULTS
  There was no early stem subsidence after surgery. Of the 80 hips, 60 (75%) showed radiographic signs of stem osseointegration including zones 3 and 5 at final follow-up. Stress shielding occurred in 50 hips (62.5%), and third-degree stress shielding was observed in 12 hips (15%). 3 patients experienced postoperative thigh pain due to distal fixation.
  
  
  CONCLUSIONS
  These short-term results indicate that the Summit stem achieved good initial fixation, although there were some cases of distal fixation. Careful long-term follow-up and observation will be necessary for hips in which stress shielding occurs.
authors.affiliation: Department of Orthopaedic Surgery, Okayama Medical Centre, Kitaku, Okayama - Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tetsunaga
authors.affiliation: Department of Orthopaedic Surgery, Okayama Medical Centre, Kitaku, Okayama - Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Orthopaedic Surgery, Okayama Medical Centre, Kitaku, Okayama - Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Shiota
authors.affiliation: Department of Orthopaedic Surgery, Okayama University Hospital, Kitaku, Okayama - Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tetsunaga
authors.affiliation: Department of Orthopaedic Surgery, Okayama Medical Centre, Kitaku, Okayama - Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Okazaki
authors.affiliation: Department of Orthopaedic Surgery, Okayama Medical Centre, Kitaku, Okayama - Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D044466:Asian People; D049628:Body Size; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000208:ethnology / Q000601:surgery*; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome