Relationship Between the Middle Genicular Artery and the Posterior Structures of the Knee: A Cadaveric Study

Sonographic Characterization of the Pericruciate Fat Pad with the Use of Compression Elastography-A Cross-Sectional Study among Healthy and Post-Injured Patients

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.

Genicular Artery Embolization: A Review of Essential Anatomic Considerations

Genicular artery embolization is increasingly recognized as a safe and effective treatment option for symptomatic knee osteoarthritis and recurrent hemarthrosis after total knee arthroplasty. Genicular arteries are an essential contributor to vascular supply for the knee joint and demonstrate considerable variability. Familiarity with the anatomy and common variations is critical for preprocedural planning, accurate target selection, and minimizing adverse events in transarterial embolization procedures. This review aimed to provide a detailed discussion of the genicular artery anatomy that is relevant to interventional radiologists performing genicular artery embolization.

Quantitative analysis of the perimeniscal position of the inferior lateral genicular artery (ILGA): magnetic resonance imaging study

PURPOSE

The inferior lateral genicular artery (ILGA) passes around the lateral knee joint, adjacent to the lateral meniscus (LM). ILGA injuries in total knee arthroplasty or arthroscopic surgery can result in recurrent hemarthrosis or painful pseudoaneurysms. Detailed information about the perimeniscal position of the ILGA relative to the LM is necessary to avoid these complications.

METHODS

3-T MR images of 100 knees (mean age 36.3 ± 11.2 years) were retrospectively reviewed. The perimeniscal area was divided into four regions: the anterior, middle, popliteal hiatus, and posterior zones. In each zone, the ILGA diameter, superoinferior position (assessed as the height of the ILGA from the LM base), and distance between the meniscocapsular junction and the ILGA were measured.

RESULTS

The distance between the ILGA and meniscocapsular junction was significantly smaller in the middle zone than in the other three zones (anterior 5.3 ± 0.8 mm, middle 1.4 ± 0.4 mm, popliteal hiatus 6.1 ± 1.0 mm, and posterior 5.6 ± 1.5 mm, p < 0.05). In the superoinferior position, the height of the ILGA was 3.4 ± 0.9 mm in the anterior zone, 0.4 ± 1.3 mm in the middle zone, - 1.9 ± 1.8 mm in the popliteal hiatus zone, and - 1.3 ± 4.3 mm in the posterior zone. When the LM bottom is the base, the ILGA was located superiorly in the anterior zone, close to the base in the middle zone, and inferiorly in the popliteal hiatus zone.

CONCLUSIONS

To avoid ILGA injury, close attention is necessary during surgical procedures involving the meniscocapsular junction of the LM, especially at the meniscal base in the middle zone.

Influence of cartilage interstitial fluid on gene expression in cruciate ligament fibroblasts

Loading of articular cartilage during motion squeezes the fluid from the cartilage, termed cartilage interstitial fluid (CIF), which was found to influence gene expression in synovial membrane cells. After crucial ligaments damage, these cells are exposed to synovial fluid containing factors released from articular cartilage; the aim of the present study was to establish the influence of CIF and factors present in CIF (CIF-like cocktails) on crucial ligament fibroblasts. CIF was squeezed from articular-epiphyseal cartilage complexes of newborn rats. Fibroblasts were obtained from crucial ligaments of adult rat knee joints. Cells were cultured in control medium, CIF and CIF-like cocktails, and the expression of selected genes was evaluated using quantitative PCR. CIF stimulated the expression of HAS1, HAS2, aggrecan, lubricin, MMP3, TIMP3 and TGFβ1. Expression of collagen type I, versican, MMP2, TIMP2, TNF and IL1β was inhibited. The CIF-like cocktail stimulated HAS1, HAS2, collagen type I, versican, aggrecan, lubricin, TIMP1, TGFβ1, IL1β, IL6 and inhibited of MMP3 and TNF expression. Both agents exerted similar effects on the expression of HAS2, aggrecan, lubricin, TGFβ1 and TNF. CIF contains inhibitory and stimulatory factors affecting gene expression in crucial ligament fibroblasts and some of them were not included in the CIF-like cocktail. Due to the powerful influence of CIF on crucial ligament fibroblasts and the synovial membrane, further studies on its composition are needed. An improved CIF like-cocktail could be applied in the treatment of various joint or tendon ailments.