Clinical and Computational Evaluation of an Anatomic Patellar Component

Lindsay T Kleeman; Jessell M Owens; Roseann M Johnson; Chadd W Clary; Jacob M Elkins; Douglas A Dennis

doi:10.1016/j.arth.2024.05.007

Clinical and Computational Evaluation of an Anatomic Patellar Component

J Arthroplasty. 2024 May 10:S0883-5403(24)00438-8. doi: 10.1016/j.arth.2024.05.007. Online ahead of print.

Authors

Lindsay T Kleeman¹, Jessell M Owens², Roseann M Johnson³, Chadd W Clary⁴, Jacob M Elkins⁵, Douglas A Dennis⁶

Affiliations

¹ Vermont Orthopaedic Clinic Dennis Rutland, VT.
² Great Basin Orthopaedics Reno, NV Colorado Joint Replacement, Denver, CO, USA.
³ Colorado Joint Replacement, Denver, CO, USA.
⁴ Center for Orthopaedic Biomechanics, University of Denver, Denver, CO.
⁵ Department of Orthopaedics, University of Iowa, Iowa City, IA.
⁶ Adjunct Professor, Dept. of Bioengineering, University of Tennessee, Denver, CO; Adjunct Professor of Bioengineering, Denver University, Denver, CO; Assistant Clinical Professor, Dept. of Orthopaedics, University of Colorado School of Medicine, Denver, CO.

PMID: 38735546
DOI: 10.1016/j.arth.2024.05.007

Abstract

Introduction: Anatomic patellar components for total knee arthroplasty (TKA) have demonstrated favorable in vivo kinematics. A novel failure mechanism in patients implanted with anatomic patella components was observed, prompting a clinical and computational investigation to identify patient and implant-related factors associated with suboptimal performance.

Methods: A retrospective evaluation was performed comparing 100 TKA patients implanted with anatomical versus 100 sex-, age-, and BMI-matched patients implanted with dome patellar components. All were implanted with the same posterior-stabilized (PS) TKA system with a minimum 1-year follow-up duration. Several radiographic parameters were assessed. A separate computational evaluation was performed using finite-element analysis, comparing components. Bone strain energy density was measured at the proximal and distal patellar poles.

Results: Patients who had anatomic patellar components had a significantly higher prevalence of anterior knee pain (AKP; 18 versus 2%, P < 0.001), chronic effusions (18 versus 2%, P < 0.001), and superior patellar pole fragmentation (36 versus 13%, P < 0.001) versus those who had dome patellar components. The anatomic group also demonstrated more lateral patellar subluxation (2.3 versus 1.1 mm, P < 0.001) and lateral tilt (5.4 versus 4.0 mm, P = 0.013). There was a higher, but not significant, number of revisions in the anatomic group (7 versus 3, P = 0.331). In computational evaluation, all simulations demonstrated increased bone strain energy density at the superior patellar pole for the anatomic patella. Resection thickness < 13 mm resulted in an over 2-fold increase in strain energy density, while a negative 7° resection angle resulted in a 6-fold higher superior pole strain energy.

Conclusion: Patients who had this design of anatomic patellar component showed higher rates of AKP, effusion, and superior pole fragmentation than patients who had dome patellae, with higher superior patella pole strain energy confirmed on computational evaluation. Avoiding higher resection angles and excessive patellar resection may improve the performance and survivorship of the anatomic patella.