title: Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients.
abstract: OBJECTIVE
  There is no consensus on the association between global femoral offset (FO) and outcome after total hip arthroplasty (THA). We assessed the association between FO and patients' reported hip function, quality of life, and abductor muscle strength.
  
  
  METHODS
  We included 250 patients with unilateral hip osteoarthritis who underwent a THA. Before the operation, the patient's reported hip function was evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and quality of life was evaluated with EQ-5D. At 1-year follow-up, the same scores and also hip abductor muscle strength were measured. 222 patients were available for follow-up. These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment).
  
  
  RESULTS
  All 3 groups improved (p < 0.001). The crude results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups.
  
  
  CONCLUSIONS
  A reduction in global FO of more than 5 mm after THA appears to have a negative association with abductor muscle strength of the operated hip, and should therefore be avoided.
authors.affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.
authors.forename: Sarwar S
authors.initials: SS
authors.lastname: Mahmood
authors.affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.
authors.forename: Sebastian S
authors.initials: SS
authors.lastname: Mukka
authors.affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.
authors.forename: Sead
authors.initials: S
authors.lastname: Crnalic
authors.affiliation: b Department of Molecular Medicine and Surgery , Karolinska Institute , Stockholm , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Wretenberg
authors.affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.
authors.forename: Arkan S
authors.initials: AS
authors.lastname: Sayed-Noor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods* / Q000523:psychology; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005270:Femur Head / Q000000981:diagnostic imaging / Q000503:physiopathology; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D011446:Prospective Studies; D011788:Quality of Life; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D018570:Risk Assessment; D013548:Sweden; D016896:Treatment Outcome