Demographic changes and surgery caseloads for hip arthroplasty over the last 50 years: a retrospective study

AIMS OF THE STUDY: Data on the demographic changes over time for hip arthroplasty are rare in Switzerland. The aim of the study was to evaluate the influence of these changes on the distribution of age, gender, operated hip side, place of residence and caseload per surgeon over the last 50 years of hip arthroplasty at the Kantonsspital St. Gallen. METHODS: For this retrospective explorative study, data were collected from the operating theatre journals of hip replacements performed at Kantonsspital St. Gallen from 1969 to 2019. Every fifth year was included, which resulted in 5-year sampling rate over the observation period. The journals were handwritten until 1999 and digital from 2004 to 2019. The following data were obtained: age, sex, type of hip arthroplasty, side of operated hip, place of residence and name of main surgeon. Apart from overall descriptive statistics, we applied the Mann-Whitney U-test to test for differences in age and the binomial test for categorical variables. A linear regression model was applied to investigate the relationship between patients' ages and historical data of life expectancy of the Swiss population. RESULTS: We included 2,963 patients, of whom 1,318 were men (median age = 67 yr., p25 = 59 yr., p75 = 74 yr.) and 1,608 women (median age = 72 yr., p25 = 63 yr., p75 = 79 yr.). Overall, women were significantly older than men, irrespective of whether they received primary total hip arthroplasty (median age = 70 yr. vs 66 yr., p25 = 61 yr. vs 58 yr., p75 = 77 yr. vs 73 yr., p <0.001), hemiarthroplasty (median age = 84 yr. vs 78.5 yr., p25 = 78 yr. vs 71 yr., p75 = 89 yr. vs 85 yr., p <0.001) or total revision arthroplasty (median age = 71 yr. vs 70 yr., p25 = 64.25 yr. vs 63 yr., p75 = 78 yr. vs 75 yr., p = 0.036). A trend toward rising median age is evident looking at the whole period observed from 1969 to 2019. Except for women in the total revision arthroplasty group (r = 0.226), a high correlation between increasing median age of patients undergoing hip replacement and life expectancy was found (r =0.663). Significantly more primary total hip prostheses (p = 0.003) and hip hemiprostheses (p <0.001) were implanted in women than in men between 1969 and 2019. Overall, no significant difference in side distribution was seen in the primary total hip arthroplasty (p = 0.061), total revision arthroplasty (p = 1.000) and hemiarthroplasty (p = 0.365) group. In contrast to earlier years, most patients in recent years are operated on by high-volume surgeons (>50 operations per surgeon per year). CONCLUSIONS: Demographic changes of patients undergoing total hip replacement reflect the overall demographic changes in the Swiss population. Over the last 50 years the indication for prosthetic hip replacements has not been extended to younger ages. The caseload in hip arthroplasty has changed over the last 50 years towards high-volume surgeons.