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J Knee Surg
DOI: 10.1055/a-2585-4964
Original Article

Reliability of a Novel Magnetic Resonance Imaging Scoring System to Evaluate Patellofemoral Osteoarthritis

Tyler J. Uppstrom
1   Department of Sports Medicine, Hospital for Special Surgery, New York
,
Guilherme Palhares
1   Department of Sports Medicine, Hospital for Special Surgery, New York
,
Robert Cecere
2   Weill Cornell Medical College, Cornell University, New York
,
Giuseppe Anzillotti
1   Department of Sports Medicine, Hospital for Special Surgery, New York
3   IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
4   Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Milan, Italy
,
Connor F. Fletcher
1   Department of Sports Medicine, Hospital for Special Surgery, New York
,
Emily Davidson
5   Department of Radiology and Imaging, Hospital for Special Surgery, New York
,
Alissa Burge
5   Department of Radiology and Imaging, Hospital for Special Surgery, New York
,
Sabrina M. Strickland 
1   Department of Sports Medicine, Hospital for Special Surgery, New York
› Author Affiliations
Funding None.
› Further Information
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Abstract

Knee osteoarthritis is a common degenerative or posttraumatic condition associated with significant pain and disability among patients. Isolated patellofemoral osteoarthritis (PFOA) occurs in approximately 24% of women and approximately 11% of men aged >55 years presenting with knee pain. In contrast to the tibiofemoral compartments, the current literature lacks a reliable magnetic resonance imaging (MRI) scoring system for quantitative evaluation of patellofemoral cartilage degeneration.

This study aimed to describe, apply, and assess the interobserver reliability of a novel MRI scoring system for assessment of the patellofemoral cartilage.

Patients who underwent patellofemoral arthroplasty for isolated PFOA between January 2012 and December 2021 were identified. Preoperative MRI scans were performed on 3.0-Tesla magnets utilizing dedicated extremity coils and standardized clinical imaging protocols consistent with International Cartilage Regeneration and Joint Preservation Society (ICRS) guidelines for the assessment of articular cartilage. A novel semiquantitative MRI patellofemoral scoring system included assessment of patellar and trochlear cartilage, bony architecture, patellofemoral alignment, and synovitis. Interobserver agreement was assessed using Cohen's Kappa coefficient for categorical variables, and the intraclass correlation coefficient (ICC) was used for the total score.

A total of 72 knee MRIs were included in the final analysis. Patellar bone edema (kappa = 0.61) and patellar cysts (kappa = 0.59) demonstrated moderate interobserver agreement. All cartilage features, trochlear bone edema and cysts, osteophytes, subchondral remodeling, patellar height, and synovitis demonstrated good interobserver agreement (kappa > 0.61). Patellofemoral alignment and total score demonstrated excellent interobserver agreement (kappa > 0.81).

The novel MRI scoring system for PFOA proposed in this study represents a comprehensive method to assess patellofemoral joint cartilage degeneration, including evaluation of patellar and trochlear cartilage changes, bony architecture, patellofemoral alignment, and synovitis. Importantly, all features of the scoring system demonstrated at least moderate interobserver agreement, with the majority of variables and total score demonstrating good to excellent agreement.

Keywords

patellofemoral - osteoarthritis - arthroplasty - magnetic resonance imaging

Note

Investigation performed at the Hospital for Special Surgery, New York, NY. This study was presented as a poster presentation at the American Orthopaedic Society for Sports Medicine (AOSSM) 2023 Annual Meeting. This study has not been previously published.


Ethical Approval

Ethical approval was approved by the Hospital for Special Surgery Institutional Review Board. IRB approved, #2020-2123.


Informed Consent

Obtained prior to enrollment in study.




Publication History

Received: 03 October 2024

Accepted: 12 April 2025

Article published online:
30 May 2025

© 2025. Thieme. All rights reserved.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA

 

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