Primary Osteoarthritis of the Hip

Aetiology & Epidemiology

Prevalence

  • 3% to 6% in the Caucasian population
  • Asian, black, & East Indian populations have very low prevalence of hip Osteoarthritis

Aetiology

  • Genetic
    • Family studies from Sweden, Britain, & the United States show ↑ rates of hip Osteoarthritis in first-degree relatives of the index patient when compared with the normal population
    • low prevalence of hip Osteoarthritis in Asian & black populations in their native countries; the low incidence of total joint replacement for primary Osteoarthritis in Asian, black, & Hispanic populations in North America; & the familial association of hip Osteoarthritis in Caucasians all suggest that genetic factors may be involved in the occurrence of this disease
  • Occupational
    • Occupations requiring heavy lifting, farming, & elite sports activity are associated with ↑ rates of hip Osteoarthritis

Osteoarthritis of the hip

Definition

  • Degeneration of the tissues of the hip joint, including hyaline cartilage, fibrocartilage, bone, & synovium

Epidemiology

  • generalised Osteoarthritis
    • >3 joint groups
  • incidence of Osteoarthritis was not related to latitude or longitude
  • highest prevalence of Osteoarthritis occurred in the Caucasians
  • It was noted that Osteoarthritis preferentially affected the distal interphalangeal joints & the first carpometacarpal joints of the hands, the knees, & the first metatarsophalangeal joints
  • Kellgren’s grading system was used to characterise the degree of hip arthritis as
    • absent (grade 0)
    • doubtful (grade 1)
    • minimal (grade 2)
    • moderate (grade 3)
    • severe (grade 4).
  • Causes of Secondary Osteoarthritis & Their Radiographic Appearance

Hip Disease in Hip Surgery

  • Patients
  • primary Osteoarthritis was the underlying disorder in nearly 90% of osteoarthritic hips
  • Rate of THR
    • Caucasians 75 per 100,000 persons
    • blacks had half the incidence
    • Asians had only one tenth.

Incidence of Predisposing Anatomic Abnormalities

  • Hip dysplasia
    • If primary Osteoarthritis of the hip is due to a subtle dysplasia, it should be seen frequently in Japanese persons, with their extremely high rate of dysplasia; however, primary Osteoarthritis is rare in that population
    • incidence of DDH in Caucasians is 0.5%. If Osteoarthritis developed in all children with DDH, this would account for only one eighth of the cases of Osteoarthritis in the Caucasian population
    • In summary, when controlled studies of acetabular measurements are done & the rates of DDH & Osteoarthritis for each racial subgroup are considered, DDH accounts for only a small percentage (5% to 10%) of hip Osteoarthritis in Caucasians
  • clinical SUFE in the adolescent occurs in only 1 of every 800 boys (an incidence of only 0.125%)
    • Anatomically normal femora accounted for more than 80% of the Osteoarthritis in their series
    • Furthermore, although there is little primary Osteoarthritis in the black & Polynesian populations, as well as a low incidence of THR performed because of Osteoarthritis, these populations have two to four times the rate of SUFE in Caucasians.

Aetiology

  • Body Weight
    • Osteoarthritis of the knee has been shown to be consistently related to obesity
    • Hip Osteoarthritis: controversial
    • no relationship between body weight or body-mass index & the occurrence of hip Osteoarthritis. However, other studies have shown an ↑ risk of Osteoarthritis of the hip in obese individuals
  • Occupational Factors
    • ? exacerbate hereditary predisposition to Osteoarthritis of the hip
      • work
        • physical demands of work have been estimated to account for 40% of cases of hip Osteoarthritis
      • carrying heavy loads
      • farmers
      • track, field, & racket sports soccer players
  • Other Anatomic Considerations
    • DDH
    • acetabular abnormality
    • femoral anteversion
      • not shown
  • Family Studies
  • In summary, two different factors appear to be involved in the aetiology of Osteoarthritis. First, the lower rates of primary Osteoarthritis in population studies of non-Caucasians & the difference in rates of THR for primary Osteoarthritis in patients with various racial backgrounds living in a common environment suggest that it is a disease primarily of Caucasians
  • Second, the relatively high incidence of the disease in siblings of Swedish & English patients who underwent THR because of primary Osteoarthritis suggests that genetic factors are operational as well

Radiographic Criteria

Primary Osteoarthritis of the Hip, radiograph of severe (tönnis grade 3) osteoarthritis of the hip
Radiograph of severe (Tönnis grade 3) osteoarthritis of the hip. Image by Mikael Häggström, Wikimedia Commons, CC0.
  • rate of secondary Osteoarthritis in the Caucasian population was not significantly different from the rates for Chinese, Filipino, Hawaiian, & Japanese subjects

Summary

  • Secondary Osteoarthritis of the hip
  • when a condition such as DDH, SUFE, or Legg-Calvé-Perthes disease results in a predisposing anatomic abnormality that leads to hip degeneration due to mechanical factors

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.