ABSTRACT
Background:
The pericruciate
fat pad (PCFP) in the
knee joint is still insufficiently studied despite its potential
role in
knee pathologies. This is the first reported study which aimed to clarify the characteristics of the PCFP in healthy individuals and contrast them with cases of post-traumatic
injuries.
Methods:
Conducted as a retrospective
cross-sectional study (n = 110 knees each) following STROBE guidelines, it employed grayscale ultrasound with echogenicity measurement, compression
elastography with
elasticity measurement, and
Color Doppler for
blood flow assessment.
Results:
PCFP showed a homogenic and hyperechoic echostructure. The echogenicity of the PCFP was higher than that of the
posterior cruciate ligament (PCL) (p < 0.001, z-score = 8.97) and of the medial
head of gastrocnemius (MHG) (p = 0.007, z-score = 2.72) in healthy knees, but lower than
subcutaneous fat (SCF) (p < 0.001, z-score = -6.52). Post-
injury/
surgery, PCFP echogenicity surpassed other structures (p < 0.001; z-score for PCL 12.2; for MHG 11.65 and for SCF 12.36) and notably exceeded the
control group (p < 0.001, z-score = 8.78). PCFP
elasticity was lower than MHG and SCF in both groups, with significantly reduced
elasticity in post-traumatic knees (ratio SCF/PCFP 15.52 ± 17.87 in case group vs. 2.26 ± 2.4 in
control group; p < 0.001; z-score = 9.65).
Blood flow was detected in 71% of healthy PCFPs with three main patterns.
Conclusions:
The main findings, indicating increased echogenicity and reduced
elasticity of PCFP post-
trauma, potentially related to
fat pad fibrosis, suggest potential applications of echogenicity and
elasticity measurements in detecting and
monitoring diverse
knee pathologies. The description of vascularity variations supplying the PCFP adds additional value to the study by emphasizing the clinically important
role of PCFP as a
bridge for the middle genicular
artery on its way to the inside of the
knee joint.
