# Increased risk of knee osteoarthritis progressing to total knee arthroplasty following patella fractures: an age stratified population analysis

## TL;DR

People who break their patella are more likely to need knee replacement surgery later, especially if they don't have surgery for the fracture.

## Contribution

This study shows nonoperative treatment of patella fractures is linked to a higher risk of needing total knee arthroplasty.

## Key findings

- Patella fracture patients had a 60% higher risk of TKA compared to the general population.
- Nonoperative treatment was associated with a higher TKA risk than operative treatment.
- The mean time from patella fracture to TKA was 4.1 years.

## Abstract

Patella fractures are articular injuries that can alter knee biomechanics, disrupt joint contact forces, and promote cartilage degeneration. However, progression to reconstructive surgery is not fully characterized. This study investigates the risk of progression to total knee arthroplasty (TKA) following patella fractures and assesses whether initial operative versus nonoperative management impacts this risk.

We retrospectively analyzed TKA progression in patients with patella fractures using synthetic data from a large Level I academic trauma center (1996–2024). Patients were identified by historic diagnostic codes for patella fractures and TKA. Age-stratified TKA rates were compared to published national data, and indirect standardization was used to calculate the age-adjusted standardized incidence ratio (SIR), risk difference (RD), and attributable risk percent (AR%).

Among 3212 native patella fractures, 263 patients (8.2%) later underwent TKA. The mean age at fracture was 58.1 years (SD 17.5) with a mean time to TKA of 4.1 years (SD 4.9). The SIR for TKA was 1.6 (95% CI 1.3–1.9), RD 3.1%, and AR% 37.2%. In the 406 operatively treated fractures (mean age 55.3 years, SD 18.6; 60.8% female), TKA occurred in 5.4% (SIR 1.4, 95% CI 0.9–2.2), compared to 8.6% in the 2,806 nonoperatively treated fractures (mean age 58.5 years, SD 17.4; 61.8% female; SIR 2.1, 95% CI 1.8–2.3) (p = 0.04).

Individuals with patella fractures face an increased lifetime risk of advanced joint degeneration and subsequent TKA compared to the general population, with nonoperative treatment linked to a higher risk than operative management. Further analysis of initial injury patterns, radiographic findings, and patient factors are in need for further research to understand and validate these findings.