Histopathological changes in the infrapatellar fat pad in an experimental rabbit model of early patellofemoral osteoarthritis

Binggang Wang; Yanfei Lang; Liu Zhang

doi:10.1016/j.knee.2018.06.010

Histopathological changes in the infrapatellar fat pad in an experimental rabbit model of early patellofemoral osteoarthritis

Knee. 2019 Jan;26(1):2-13. doi: 10.1016/j.knee.2018.06.010. Epub 2018 Nov 8.

Authors

Binggang Wang¹, Yanfei Lang², Liu Zhang³

Affiliations

¹ Department of Orthopedic Surgery, Hebei Medical University, Shijiazhuang, China.
² Department of Orthopedic Surgery, The Affiliated Hospital of North China University of Science and Technology, Tangshan, China.
³ Department of Orthopedic Surgery, Hebei Medical University, Shijiazhuang, China; Department of Orthopedic Surgery, The Affiliated Hospital of North China University of Science and Technology, Tangshan, China. Electronic address: zhliu130@sohu.com.

PMID: 30415972
DOI: 10.1016/j.knee.2018.06.010

Abstract

Background: The purpose of this study was to characterise the histopathological changes in the infrapatellar fat pad (IPFP) in the early stage of patellofemoral osteoarthritis (PFOA).

Methods: Sixty-four New Zealand white rabbits were randomly divided into experimental (n = 24), sham (n = 16), and control groups (n = 24). In the experimental group, denoted as the patellar ligament uneven shortening group (US group), the patellar ligament (PL) was folded eight millimetres and sutured. After eight weeks, all animals were euthanised, and magnetic resonance imaging (MRI) evaluation, wet IPFP weight measurement, and histopathological and immunohistochemistry analysis were performed to analyse the histopathological changes in the IPFPs.

Results: The maximum cross-sectional area (CSA) of the IPFPs in the sagittal position of MRI in the control group, sham group, and US group were 45.50 ± 7.19 mm², 45.88 ± 6.60 mm² (vs. control group, P = 0.907), and 53.83 ± 8.24 mm² (vs. control group, P = 0.015; vs. sham group, P = 0.035), respectively. The MRI intensity of the IPFPs in the control group, sham group, and US group were 115.53 ± 28.85, 108.53 ± 26.73 (vs. control group, P = 0.589), and 154.52 ± 18.48 (vs. control group, P = 0.002; vs. sham group, P = 0.002), respectively. The wet weight of the IPFPs in the control group, sham group, and US group were 0.32 ± 0.05 g, 0.32 ± 0.04 g (vs. control group, P = 0.895), and 0.38 ± 0.06 g (vs. control group, P = 0.017; vs. sham group, P = 0.033), respectively. The Osteoarthritis Research Society International (OARSI) scores of the IPFPs in the US group were 6.00 ± 1.91, which was higher than the scores of 2.50 ± 2.02 (P < 0.001) in the control group and of 2.75 ± 1.67 (P = 0.001) in the sham group.

Conclusions: The histopathological changes of the IPFPs as determined via MRI and microscopic structure appeared to occur much earlier than cartilage damage in PFOA. Furthermore, detecting and treating the IPFP changes may offer aid in the diagnosis and treatment of PFOA.

Keywords: Anterior knee pain; Infrapatellar fat pad; Knee; Osteophyte; Patellofemoral osteoarthritis; Synovitis.

MeSH terms

Adipose Tissue / pathology*
Animals
Disease Models, Animal
Female
Knee Joint / pathology
Magnetic Resonance Imaging / methods*
Osteoarthritis, Knee / pathology*
Patellar Ligament / pathology*
Rabbits
Time Factors