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

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

• References

• 1 Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet 2019; 393 (10182): 1745-1759
• 2 Hiligsmann M, Cooper C, Arden N. et al. Health economics in the field of osteoarthritis: an expert's consensus paper from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO). Semin Arthritis Rheum 2013; 43 (03) 303-313
• 3 Allen KD, Thoma LM, Golightly YM. Epidemiology of osteoarthritis. Osteoarthritis Cartilage 2022; 30 (02) 184-195
• 4 Loeser RF, Goldring SR, Scanzello CR, Goldring MB. Osteoarthritis: a disease of the joint as an organ. Arthritis Rheum 2012; 64 (06) 1697-1707
• 5 Martel-Pelletier J, Barr AJ, Cicuttini FM. et al. Osteoarthritis. Nat Rev Dis Primers 2016; 2: 16072
• 6 McAlindon TE, Snow S, Cooper C, Dieppe PA. Radiographic patterns of osteoarthritis of the knee joint in the community: the importance of the patellofemoral joint. Ann Rheum Dis 1992; 51 (07) 844-849
• 7 Donell ST, Glasgow MM. Isolated patellofemoral osteoarthritis. Knee 2007; 14 (03) 169-176
• 8 Delanois RE, McGrath MS, Ulrich SD. et al. Results of total knee replacement for isolated patellofemoral arthritis: when not to perform a patellofemoral arthroplasty. Orthop Clin North Am 2008; 39 (03) 381-388 , vii
• 9 Vasso M, Corona K, Capasso L, Toro G, Schiavone Panni A. Intraarticular injection of microfragmented adipose tissue plus arthroscopy in isolated primary patellofemoral osteoarthritis is clinically effective and not affected by age, BMI, or stage of osteoarthritis. J Orthop Traumatol 2022; 23 (01) 7
• 10 van Jonbergen HP, Werkman DM, Barnaart LF, van Kampen A. Long-term outcomes of patellofemoral arthroplasty. J Arthroplasty 2010; 25 (07) 1066-1071
• 11 Zhao J. Arthroscopic debridement, facetectomy, and synovectomy for isolated patellofemoral osteoarthritis. Arthrosc Tech 2021; 10 (12) e2741-e2745
• 12 Kuwabara A, Cinque M, Ray T, Sherman SL. Treatment options for patellofemoral arthritis. Curr Rev Musculoskelet Med 2022; 15 (02) 90-106
• 13 Carofino BC, Fulkerson JP. Anteromedialization of the tibial tubercle for patellofemoral arthritis in patients > 50 years. J Knee Surg 2008; 21 (02) 101-105
• 14 Elbardesy H, McLeod A, Gul R, Harty J. Midterm results of modern patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral arthritis: systematic review and meta-analysis of comparative studies. Arch Orthop Trauma Surg 2022; 142 (05) 851-859
• 15 Peng G, Liu M, Guan Z. et al. Patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral osteoarthritis: a systematic review and meta-analysis. J Orthop Surg Res 2021; 16 (01) 264
• 16 Segal NA, Murphy MT, Everist BM. et al. Clinical value of weight-bearing CT and radiographs for detecting patellofemoral cartilage visualized by MRI in the MOST study. Osteoarthritis Cartilage 2021; 29 (11) 1540-1548
• 17 Hunter DJ, Zhang W, Conaghan PG. et al. Systematic review of the concurrent and predictive validity of MRI biomarkers in OA. Osteoarthritis Cartilage 2011; 19 (05) 557-588
• 18 Hunter DJ, Zhang W, Conaghan PG. et al. Responsiveness and reliability of MRI in knee osteoarthritis: a meta-analysis of published evidence. Osteoarthritis Cartilage 2011; 19 (05) 589-605
• 19 Peterfy CG, Guermazi A, Zaim S. et al. Whole-Organ Magnetic Resonance Imaging Score (WORMS) of the knee in osteoarthritis. Osteoarthritis Cartilage 2004; 12 (03) 177-190
• 20 Hunter DJ, Lo GH, Gale D, Grainger AJ, Guermazi A, Conaghan PG. The reliability of a new scoring system for knee osteoarthritis MRI and the validity of bone marrow lesion assessment: BLOKS (Boston Leeds Osteoarthritis Knee Score). Ann Rheum Dis 2008; 67 (02) 206-211
• 21 Hunter DJ, Guermazi A, Lo GH. et al. Evolution of semi-quantitative whole joint assessment of knee OA: MOAKS (MRI Osteoarthritis Knee Score). Osteoarthritis Cartilage 2011; 19 (08) 990-1002
• 22 Davidson EJ, Figgie C, Nguyen J. et al. Chondral injury associated with ACL injury: Assessing progressive chondral degeneration with morphologic and quantitative MRI techniques. Sports Health 2024; 16 (05) 722-734
• 23 Potter HG, Jain SK, Ma Y, Black BR, Fung S, Lyman S. Cartilage injury after acute, isolated anterior cruciate ligament tear: immediate and longitudinal effect with clinical/MRI follow-up. Am J Sports Med 2012; 40 (02) 276-285
• 24 Noyes FR, Stabler CL. A system for grading articular cartilage lesions at arthroscopy. Am J Sports Med 1989; 17 (04) 505-513
• 25 Li D, Bi AS, Samra SS, Samra NS, Wu D, Ma Y. Functional outcomes following total knee arthroplasty without patellar resurfacing: A minimum two-year follow-up retrospective cohort study. Cureus 2021; 13 (06) e16036
• 26 Nha KW, Oh SM, Ha YW, Patel MK, Seo JH, Lee BH. Radiological grading of osteoarthritis on Rosenberg view has a significant correlation with clinical outcomes after medial open-wedge high-tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2019; 27 (06) 2021-2029
• 27 Rodríguez-Merchán EC, Gómez-Cardero P. The outerbridge classification predicts the need for patellar resurfacing in TKA. Clin Orthop Relat Res 2010; 468 (05) 1254-1257
• 28 Hill JR, Oei EHC, Crossley KM. et al. Contemporary methods of acquiring patellofemoral joint radiography and grading of patellofemoral osteoarthritis: a systematic review. Osteoarthritis Cartilage 2022; 28: S288