Source and hub of inflammation: The infrapatellar fat pad and its interactions with articular tissues during knee osteoarthritis

Zhou, Sijia; Maleitzke, Tazio; Geißler, Sven; Hildebrandt, A.; Fleckenstein, Florian Nima; Niemann, Marcel; Fischer, Heilwig; Perka, Carsten; Duda, Georg N.; Winkler, Tobias

doi:10.1002/jor.25347

Cited by 33 publications

(17 citation statements)

References 104 publications

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“…Coinciding with descriptions from human medical literature [ 13 ], the equine IFP was highly vascularized and consisted of lobules of white adipose tissue characterized by a significant amount of fibrous stroma, which is typical for areas subjected to considerable mechanical stress. The fibrous septa were thicker in central areas of the fat pad, and thinner towards the periphery.…”

Section: Discussionmentioning

confidence: 92%

“…There is also a paucity in the equine scientific literature regarding the infrapatellar fat pad (IFP), and its potential contribution to stifle disease. In human medical literature, IFP hypertrophy has been associated with patellar tendinopathy [ 12 ] and the IFP is increasingly recognized as a major contributor in pathological joint states such as anterior knee pain and osteoarthrosis [ 13 ]. Furthermore, the IPF is hypothesized to be an active component of the joint organ with multifunctional roles in the maintenance of joint homeostasis, as it contains immune cells, inflammatory cells and substance P nerve cells, all of which may play a role in disease development and could contribute to OA [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

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The equine patellar ligaments and the infrapatellar fat pad – a microanatomical study

Fjordbakk

Marques-Smith

2023

BMC Vet Res

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Background Interpretation of patellar ligament (PL) ultrasonography may be difficult, as hypoechoic or heterogenous echogenicity are common findings. Verifying suspected disease of equine PLs by histopathology is also problematic as descriptions of normal PL vascularity and histology are scarce. The current study describes the PL and infrapatellar fat pad (IFP) vascular pattern from computed tomography scans of barium perfused normal equine specimens (n = 8; age 10 days to 18 years), as well as routine histology to serve as a reference for future investigations into PL pathology and IFP disease. Results The PLs received a bipolar blood supply. Vascular architecture consisted of numerous distinct longitudinal vessels with several horizontal connections, which branched into extensive latticeworks of smaller vessels throughout the ligaments. Several vascular connections between the PLs and the IFP were identified. One distinct longitudinal vessel was seen entering each of the IFP lobes at the distocranial aspect, branching extensively into lobar vascular networks which anastomosed by several horizontal branches at the mid portion of the IFP where the two lobes merge. Histologically, there were large variations in PL interfascicular endotenon thickness, vascularity and fatty infiltration; these parameters increased with age for the intermediate and medial PL. Areas of metaplastic tenocytes / chondroid metaplasia were identified in all investigated adult medial PLs; in 2/7 in the intermediate PL and in 4/7 in the lateral PL. The adult IFP consisted of white unilocular adipose tissue, organized in lobules separated by thin connective tissue septa increasing in thickness towards the periphery and the distocentral aspect. Conclusions The equine PLs and IFP are highly vascularized structures with ample vascular connections suggestive of crosstalk. This, together with the large variation in PL endotenon thickness, vascularity and fatty infiltration, should be taken into consideration when assessing potential PL histopathology as these changes increase with age and are found in horses without clinical signs of stifle disease. Metaplastic tenocytes / chondroid metaplasia should be considered a normal finding throughout the medial PL and is not age dependent. The role of the equine IFP in stifle disease has yet to be elucidated.

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The equine patellar ligaments and the infrapatellar fat pad – a microanatomical study

Fjordbakk

Marques-Smith

2023

BMC Vet Res

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“…This discrepancy may be attributed to the difficulty of measuring the thickness for the fenestra and vertical septum type. Or, these data may suggest that the ligament itself does not reflect the level of KOA, unlike the IPFP that does [16, 18–21, 28].…”

Section: Discussionmentioning

confidence: 99%

“…In clinical cases with AKP, its resection resulted in a significant reduction in perceived pain [10,12,13]. It may also be resected in ACL reconstruction surgeries to spare the IPFP, a structure frequently researched for its beneficial and detrimental role in AKP and KOA [14][15][16][17][18][19][20][21][22][23]. Studies describe the ligament's microscopic anatomy to be like that of other ligaments in the knee, though with a smaller tensile strength, suggesting only a minor role in knee stabilization and/or knee mobility [24,25].…”

Section: Introductionmentioning

confidence: 99%

The ligamentum mucosum’s potential as a preventative structure in the development of knee osteoarthritis

Martin,

Liu,

Alimohammadi

2023

J. exp. orthop.

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Purpose This paper aimed to identify whether the presence, type, and/or morphology of the ligamentum mucosum could play a role in the development of knee osteoarthritis. Since its microscopic structure is alike that of other knee ligaments, it was hypothesized that its presence could facilitate knee motion and stability, thus preventing or reducing the extent of knee osteoarthritis. Methods Thirty three cadavers (a total of 51 knees) were dissected. The ligamentum mucosum, if present, was measured with a digital caliber and a measuring tape in terms of length, width, and thickness. Knee osteoarthritis was assessed in six regions of the knee. The OuterBridge Classification System (Grades 0–4) was used to visually assess the extent, in addition to probing the area. Osteoarthritis was deemed present if the grade was 2 or greater. Results The presence of the ligament was associated with a lower mean osteoarthritis level in the trochlear groove and lateral tibial plateau regions (p < 0.001 and p = 0.013, respectively). Overall osteoarthritis of the knee was also present at varying levels for each type of the ligamentum mucosum (p < 0.001). The patella and the medial condyle had the greatest levels of osteoarthritis, while the medial and lateral tibial plateaus had the lowest levels. Conclusion The presence of the ligamentum mucosum is linked with decreased osteoarthritis in the trochlear groove region. In addition, both the absent ligament and its classification as a vertical septum are associated with increased knee osteoarthritis. Level of evidence Five.

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“…The infrapatellar fat pad (IPFP), an adipose tissue structure located in the anterior compartment of the knee, has been implicated in the progression of knee osteoarthritis and as a potential source of postoperative knee pain due to its substantial innervation, high proportion of substance-p containing fibers, and proximity to the synovial lining. [6][7][8][9] TKA surgery can lead to chronic inflammation of the IPFP that can develop into scar tissue over time. 10 Fibrosis of the IPFP can present clinically as anterior knee pain, stiffness, range of motion loss, and functional limitations.…”

mentioning

confidence: 99%

MAVRIC based T2 mapping assessment of infrapatellar fat pad scarring in patients with total knee arthroplasty

Sacher

Neri

Gao

et al. 2022

Journal Orthopaedic Research

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The infrapatellar fat pad (IPFP) has been implicated as a source of postoperative knee pain. Imaging the IPFP is challenging in patients with total knee arthroplasty (TKA) due to metallic susceptibility artifact. Multi‐Acquisition Variable‐Resonance Image Combination (MAVRIC)‐based T2 Mapping has been developed to mitigate this artifact and can generate quantitative T2 data. Objectives of this study were to (1) measure T2 values of the IPFP in patients with TKAs using a MAVRIC based T2 mapping technique and (2) determine if IPFP T2 values are related to the degree of fat pad scarring or clinical magnetic resonance imaging (MRI) findings. Twenty‐eight subjects (10 males, 18 females, Age: 66 + 7.2 years [Mean ± standard deviations]) undergoing clinical MRIs were sequentially recruited. Morphological imaging and quantitative T2 mapping sequences were performed on a clinical 1.5 T scanner. The morphologic images were graded for the presence and severity of fat pad scarring and clinical outcomes. T2 values were calculated in the total fat pad volume, a normal regions of interest (ROI), and an abnormal ROI. T2 values were shortened in the total IPFP volume (p = 0.001) and within abnormal regions (p = 0.003) in subjects with more severe IPFP scarring. The difference between T2 values in normal−abnormal regions was greater in subjects with severe versus no scarring (+1426.1%, p = 0.008). T2 values were elevated in patients with MRI findings of osteolysis (+32.3%, p = 0.02). These findings indicate that MAVRIC‐based T2 Mapping may be used as a quantitative biomarker of postoperative IPFP scarring in individuals following TKA.

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Source and hub of inflammation: The infrapatellar fat pad and its interactions with articular tissues during knee osteoarthritis

Cited by 33 publications

References 104 publications

The equine patellar ligaments and the infrapatellar fat pad – a microanatomical study

The equine patellar ligaments and the infrapatellar fat pad – a microanatomical study

The ligamentum mucosum’s potential as a preventative structure in the development of knee osteoarthritis

MAVRIC based T2 mapping assessment of infrapatellar fat pad scarring in patients with total knee arthroplasty

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