What are the predisposing factors for periprosthetic fractures following total hip arthroplasty? – a National Inpatient Sample-based study

With a progressive rise in the number of total hip arthroplasties (THA) over the past decades, the proportion of patients sustaining peri-prosthetic fractures (PPF) has been substantially increasing. In this context, the need for clearly understanding the factors predisposing patients to PPF following THA and the impact of these adverse complications on the overall healthcare burden cannot be understated.

Based upon the Nationwide Inpatient Sample (NIS) database, the patients who underwent THA in the United States between 2016 and2019 (with ICD-10 CMP code) were identified. The patients were divided into 2 groups; group A – patients who sustained PPF and group B – those who did not. The information about the patients’ demographic profile, medical comorbidities; and hospital admission (including length of stay and expenditure incurred) were analysed; and compared between the 2 groups.

Overall, 367,890 patients underwent THA, among whom 4,425 (1.2%) sustained PPF (group A). The remaining patients were classified under group B (363,465 patients). On the basis of multi-variate analysis (MVA), there was a significantly greater proportion of females, elderly patients, and emergent admissions (p < 0.001) in group A. The length of hospital stay, expenditure incurred and mortality were also significantly higher (p = 0.001) in group A. Based on MVA, Down’s syndrome (odd’s ratio 3.15, p = 0.01), H/O colostomy (odd’s ratio 2.09, p = 0.008), liver cirrhosis (odd’s ratio 2.01, p < 0.001), Parkinson’s disease (odd’s ratio 1.49, p = 0.004), morbid obesity (odd’s ratio 1.44, p < 0.001), super obesity (odd’s ratio 1.49, p = 0.03), and H/O CABG (coronary artery bypass graft; odd’s ratio 1.21, p = 0.03) demonstrated significant association with PPF (group A).

Patients with PPF require higher rates of emergent admission, longer hospital stay and greater admission-related expenditure. Female sex, advanced age, morbid or super obesity, and presence of medical comorbidities (such as Down’s syndrome, cirrhosis, Parkinson’s disease, previous colostomy, and previous CABG) significantly enhance the risk of PPF after THA. These medical conditions must be kept in clinicians’ minds and close follow-up needs to be implemented in such situations so as to mitigate these complications.