ABSTRACT
OBJECTIVES: There are few Australian data that examine the association between total knee joint replacement (TKR) utilisation and socioeconomic status (SES). This study examined TKR surgeries with a diagnosis of osteoarthritis (OA) performed for residents of Barwon Statistical Division (BSD) for 2006-2007. DESIGN: Cross-sectional. SETTING: BSD, South-eastern Victoria, Australia PARTICIPANTS: All patients who underwent a TKR for OA, 2006-2007, and whose residential postcode was identified as within the BSD of Australia, and for whom SES data were available, were eligible for inclusion. PRIMARY OUTCOME MEASURE: Primary TKR data ascertained from the Australian Orthopaedic Association National Joint Replacement Registry. Residential addresses were matched with the Australian Bureau of Statistics census data, and the Index of Relative Socioeconomic Disadvantage was used to determine SES, categorised into quintiles whereby quintile 1 indicated the most disadvantaged and quintile 5 the least disadvantaged. Age-specific and sex-specific rates of TKR utilisation per 1000 person-years were reported for 10-year age bands. RESULTS: Females accounted for 62.7% of the 691 primary TKR surgeries performed during 2006-2007. The greatest utilisation rates of TKR in males was 7.6 observed in those aged >79 years, and in 10.2 in females observed in those aged 70-79 years. An increase in TKR was observed for males in SES quintile four compared to quintile 1 in which the lowest utilisation which was observed (p=0.04). No differences were observed in females across SES quintiles. CONCLUSIONS: Further investigation is warranted on a larger scale to examine the role that SES may play in TKR utilisation, and to determine whether any social disparities in TKR utilisation reflect health system biases or geographic differences.
ABSTRACT
OBJECTIVES: Animal and in vitro studies suggest that parathyroid hormone (PTH) may affect articular cartilage. However, little is known of the relationship between PTH and human joints in vivo. DESIGN: Longitudinal. SETTING: Barwon Statistical Division, Victoria, Australia. PARTICIPANTS: 101 asymptomatic women aged 35-49 years (2007-2009) and without clinical knee osteoarthritis, selected from the population-based Geelong Osteoporosis Study. RISK FACTORS: Blood samples obtained 10 years before (1994-1997) and stored at -80°C for random batch analyses. Serum intact PTH was quantified by chemiluminescent enzyme assay. Serum 25-hydroxyvitamin D (25(OH)D) was assayed using equilibrium radioimmunoassay. Models were adjusted for age, bone area and body mass index; further adjustment was made for 25(OH)D and calcium supplementation. OUTCOME: Knee cartilage volume, measured by MRI. RESULTS: A higher lnPTH was associated with reduced medial-but not lateral-cartilage volume (regression coefficient±SD, p value: -72.2±33.6 mm(3), p=0.03) after adjustment for age, body mass index and bone area. Further sinusoidal adjustment (-80.8±34.4 mm(3), p=0.02) and 25(OH)D with seasonal adjustment (-72.7±35.1 mm(3), p=0.04), calcium supplementation and prevalent osteophytes did not affect the results. CONCLUSIONS: A higher lnPTH might be detrimental to knee cartilage in vivo. Animal studies suggest that higher PTH concentrations reduce the healing ability of cartilage following minor injury. This may be apparent in the presence of increased loading, which occurs in the medial compartment, placing the medial cartilage at higher risk for injury.
