Study design: Longitudinal laboratory study.
Objectives: (1) To compare gait characteristics between individuals with early-stage hip osteoarthritis who underwent total hip replacement (THR) and those who did not undergo THR, and (2) to evaluate whether gait characteristics, function, and symptoms declined among individuals who did not undergo THR during a 6- to 7-year follow-up.
Background: The natural history of symptoms, function, and gait changes secondary to hip osteoarthritis, including potential differences at an early stage of disease, is unknown.
Methods: Forty-three individuals (mean age, 58.9 years) with radiographic and symptomatic hip osteoarthritis participated. Outcome measures included 3-D gait analysis; self-reported pain, stiffness, and function; hip range of motion; and the six-minute walk test. Baseline comparisons between individuals who later underwent THR and those who did not undergo THR were made using independent t tests or Mann-Whitney U tests. Comparisons of baseline measures and 6- to 7-year follow-up for the nonoperated individuals were conducted with paired-samples t tests or Wilcoxon signed-rank tests (P<.05).
Results: Twelve (27.9%) of the 43 individuals initially evaluated had not undergone THR at the 6- to 7-year follow-up. At baseline, these individuals had larger sagittal plane hip and knee joint excursions, larger joint space width, lower body mass index, and superior self-reported function compared with the individuals who later underwent THR. At the 6- to 7-year follow-up, the individuals who did not undergo THR exhibited no decline in gait characteristics, minimum joint space, or overall function. Furthermore, their self-reported pain had significantly decreased (P = .024).
Conclusion: Individuals who did not undergo THR during a 6- to 7-year follow-up period did not exhibit a decline in gait, function, or symptoms compared to those who underwent THR. These findings are suggestive of a phenotype of hip osteoarthritis with a very slow disease progression, particularly in regard to pain.
Level of evidence: Prognosis, level 1b.
Trial registration: ClinicalTrials.gov NCT00319423.
Keywords: biomechanics; joint deterioration; motion analysis; nonoperative natural history.