Disentangling the detrimental effects of local from systemic adipose tissue dysfunction on articular cartilage in the knee.

OBJECTIVE: Obesity increases osteoarthritis (OA) risk due to adipose tissue dysfunction with associated metabolic syndrome and excess weight. Lipodystrophy syndromes exhibit systemic metabolic and inflammatory abnormalities similar to obesity without biomechanical overloading. Here, we used lipodystrophy mouse models to investigate the effects of systemic versus intra-articular adipose tissue dysfunction on the knee. METHODS: Intra-articular adipose tissue development was studied using reporter mice. Mice with selective lipodystrophy of intra-articular adipose tissue were generated by conditional knockout (cKO) of Bscl2 in Gdf5-lineage cells, and compared with congenital Bscl2 knockout (KO) mice with generalised lipodystrophy and associated systemic metabolic dysfunction. OA was induced by surgically destabilising the medial meniscus (DMM) and obesity by high-fat diet (HFD). Gene expression was analysed by quantitative RT-PCR and tissues were analysed histologically. RESULTS: The infrapatellar fat pad (IFP), in contrast to overlying subcutaneous adipose tissue, developed from a template established from the Gdf5-expressing joint interzone during late embryogenesis, and was populated shortly after birth by adipocytes stochastically arising from Pdgfrα+ Gdf5-lineage progenitors. While female Bscl2 KO mice with generalised lipodystrophy developed spontaneous knee cartilage damage, Bscl2 cKO mice with intra-articular lipodystrophy did not, despite synovial hyperplasia and inflammation of the residual IFP. Furthermore, male Bscl2 cKO mice showed no worse cartilage damage after DMM. However, female Bscl2 cKO mice with intra-articular lipodystrophy showed increased susceptibility to the cartilage-damaging effects of HFD-induced obesity. CONCLUSION: Our findings emphasise the prevalent role of systemic metabolic and inflammatory effects in impairing cartilage homeostasis, with a modulatory role for intra-articular adipose tissue.

Hoffa's fat pad ganglion cyst of the knee: a case report of a rare cause of knee pain and swelling.

Introduction and importance: Hoffa's fat pad (HFP), also known as infrapatellar fat pad, is one of the three fat pads in the knee. Ganglion cyst (GC) rarely arises from HFP which presents knee pain and swelling. Case presentation: A 43-year-old female presented with left knee pain for 1 year and swelling in her left knee for 6 months. Clinical examination revealed a palpable swelling of size around 3 cm×2 cm over the anteromedial aspect of the left knee. The size of the swelling increased on extension and decreased on flexion of the knee. A musculoskeletal ultrasound of the left knee revealed a lobulated anechoic lesion of size ∼2.3 cm×2 cm in HFP. Open excision of cystic mass through medial parapatellar approach was done, and histopathological examination showed findings consistent with GC. At 6 months follow-up, there was no residual swelling and no recurrence. She was symptom-free on her recent evaluation after 1 year of operation. Clinical discussion: GCs arising from HFP are much rarer among the cysts around the knee. Diagnosis is primarily done by magnetic resonance imaging. However, the use of ultrasonography has grown in the diagnosis of the GC. Among different modalities of treatment, open excision is the most recommended to prevent recurrence and incomplete resection. Conclusions: This case illustrates the importance of ultrasonography in the early diagnosis of HFP GC and reserving more costly and time-consuming imaging modality magnetic resonance imaging for localizing the extent of the cyst. We recommend an open resection to avoid recurrence and incomplete resection of the cyst.

Dynamic ultrasound assessment for insertional achilles tendinopathy: the COcco-RIcci (CORI) sign.

OBJECTIVE: To describe a novel, dynamic ultrasound assessment of the Achilles tendon at the calcaneal insertion taking advantage of the effusion within the deep retrocalcaneal bursa as a natural contrast agent. MATERIALS AND METHODS: Positioning the ultrasound transducer in a longitudinal plane over the Achilles tendon at the calcaneal insertion, manual compression of the deep retrocalcaneal bursa can be performed using the other hand. Dynamically shifting the anechoic effusion from the proximal to the distal compartment of the bursa, the undersurface of the Achilles tendon is lifted from the underlying cortical bone of the superior facet of the calcaneal tuberosity. RESULTS: Pushing the anechoic effusion from the bursal cavity toward the undersurface of the Achilles tendon, an eventual focal injury of its deep fibers can be visualized dynamically during the maneuver as a "black crescent" within the tendon-i.e., the COcco-RIcci (CORI) sign. Otherwise, the gliding of the posteroinferior wedge of the Kager's fat pad inside the tendon-bone interface can be observed in normal conditions. CONCLUSION: The CORI sign is a novel sonographic sign to further enhance the diagnostic accuracy of dynamic ultrasound imaging in patients with insertional Achilles tendinopathy especially to detect focal injury involving the deep fibers of the tendon.

Changes in functional characteristics of heel fat pad with age.

BACKGROUND: This study aimed to investigate age-related changes in the heel fat pad's microchamber and macrochamber layers, particularly focusing on load-induced alterations. Understanding these changes is crucial for elucidating age-related differences in foot mechanics and their potential implications for mobility and comfort. METHODS: Fifty-five healthy individuals were divided into three age groups: young adults (≤29 years), middle-aged adults (30-44 years), and elderly individuals (≥45 years). Ultrasonic imaging was utilized to measure the thickness of the heel fat pad's microchamber and macrochamber layers under varying load conditions. Thickness, percentage changes, and ratios of load-induced thickness changes were calculated to assess age-related differences. FINDINGS: Under no-load conditions, both microchamber and macrochamber layers of the heel fat pad were significantly thicker in middle-aged and elderly individuals than in young adults. When load was applied middle-aged and elderly participants exhibited smaller changes in the macrochamber layer and larger changes in the microchamber layer compared to young adults. INTERPRETATION: Our findings suggest that age influences the structural characteristics and response of the heel fat pad to mechanical loading. Thicker heel fat pad layers in middle-aged and elderly individuals under no-load conditions may reflect age-related changes in fat distribution or composition. Moreover, differences in load-induced thickness changes indicate altered mechanical properties with age, potentially affecting shock absorption and overall foot function. Understanding these age-related variations can help develop interventions aimed at preserving foot health and mobility across the lifespan.

Interobserver agreement and diagnostic challenges of Congo red staining for amyloid detection on fat pad aspiration biopsies.

INTRODUCTION: Congo red staining of fat pad fine needle aspiration specimens is a method utilized for evaluation of amyloid deposition. However, these specimens can pose diagnostic challenges for cytopathologists. As part of ongoing internal quality improvement measures, the objective of this study was to evaluate the intradepartmental interobserver agreement of these specimens and to identify factors that affect the variability of the interpretations. MATERIALS AND METHODS: There were 7 participants, which included 3 trainees, 3 cytopathologists, and 1 cytotechnologist. Each participant reviewed 50 Congo red stained fat pad fine needle aspiration slides. The interpretations were categorized into 3 groups: negative, indeterminate/suspicious, and positive. The participants also noted any interpretation challenges they encountered for each case. RESULTS: There was only slight interobserver agreement among all participants (κ = 0.133). Stratified by participant group, the interobserver agreement among the trainees was slight bordering on poor (κ = 0.028) and among cytopathologists was fair (κ = 0.249). The highest agreement between 2 observers was between 2 cytopathologists and the level of agreement was moderate bordering on fair (κ = 0.426). There were only 3 cases (6.0%) with full agreement among observers, while in 25 cases (50.0%), there were 2 category differences in interpretations. The primary diagnostic challenge reported by participants was when weak or focal birefringence was encountered as well as cases complicated by poor stain quality and overstaining. CONCLUSIONS: We found only slight interobserver agreement among all study participants. A major area of challenge was cases with weak birefringence resulting in high variance of interpretation among participants.

Infrapatellar fat pad size and subcutaneous fat in knee osteoarthritis radiographic progression: data from the osteoarthritis initiative.

OBJECTIVES: Adipose tissue has been associated with knee osteoarthritis (KOA) pathogenesis, but the longitudinal changes in adipose tissue with KOA progression have not been carefully evaluated. This study aimed to determine if longitudinal changes of systemic and local adipose tissue is associated with radiographic progression of KOA. METHODS: This case-control study used data from the Osteoarthritis Initiative (OAI) and included 315 cases (all the right knees with a minimum of Kellgren-Lawrence score (KL) of 0 and an increase of ≥ 1 KL from baseline to 48 months) and 315 controls matched by age, sex, race, and baseline KL. Cross sectional area of IPFP (IPFP CSA) and subcutaneous adipose tissue around the distal thigh (SCATthigh) were measured using MRI images at baseline and 24 months. Conditional logistic regression models were fitted to estimate associations of obesity markers, IPFP CSA, and SCATthigh with radiographic KOA progression. Mediation analysis was used to assess whether IPFP CSA or SCATthigh mediates the relationships between baseline BMI and radiographic KOA progression. RESULTS: 24-month changes of IPFP CSA (ΔIPFP CSA) and SCATthigh (ΔSCATthigh) were significantly greater in cases compared to controls, whereas Δ BMI and Δ abdominal circumference were similar in both groups during follow-up. Adjusted ORs for radiographic KOA progression were 9.299, 95% CI (5.357-16.141) per 1 SD increase of Δ IPFP CSA and 1.646, 95% CI (1.288-2.103) per 1 SD increase of Δ SCATthigh. ΔIPFP CSA mediated the association between baseline BMI and radiographic KOA progression (87%). CONCLUSIONS: Subjects with radiographic progression of KOA, had significant increases in IPFP CSA and subcutaneous adipose tissue while BMI and abdominal circumference remained stable. Additional studies are needed to confirm these associations.

Are short term outcomes superior following total knee arthroplasty when infra-patellar fat pad is resected? A systematic review and meta-analysis.

BACKGROUND: Data suggests the infra-patellar fat pad (IPFP) is resected in the majority of total knee arthroplasty cases. Current literature suggests there may be scope for increasing preservations rates. A systematic review and meta-analysis of available literature was performed to assess if resection of IPFP resulted in superior patient outcomes. METHODS: Scopus, PubMed, Cochrane, Embase and CINAHL were systematically searched in February 2024 for articles of relevance and meta-analysis conducted. A standardized mean difference and confidence interval of 95% was calculated. An odds ratio was calculated for all included datasets. Heterogeneity was assessed for using the I2 statistic. RESULTS: Thirteen studies were included within this review. IPFP resection shortened the patella tendon at 6 months post-operatively (OR, 0.07; 95% CI, 0.02-0.12, P = 0.006). Results favoured preservation at 12 months post-operatively (OR, 0.02; 95% CI, -0.02 to 0.06, P = 0.32). Oxford Knee Society (OKS) results statistically favoured preservation at 6 months (OR, 1.57; 95% CI, 0.74-2.39, P = 0.0002). Findings at 12 months favoured resection (OR, -0.49; 95% CI, -5.39, 4.41, P = 0.84). Resection increased anterior knee pain at 6-12 months post-operatively (OR, 1.45; 95% CI, 1.12-1.89, P = 0.005). Combined subgroup analysis of flexion favoured resection (OR, -2.15; 95% CI, -6.52 to 2.22, P = 0.34). CONCLUSION: OKS and patella tendon length results favoured preservation at 6 months however did not reach minimal clinically important difference. Combined subgroup analysis of flexion did not yield a statistically significant result. Rates of anterior knee pain at 6-12 months favoured preservation.

Advancements in Face and Neck Contouring: Integrating Radiofrequency-Assisted Liposuction with FaceTite and Buccal Fat Pad Excision for Facial Slimming.

BACKGROUND: The integration of neck liposuction with FaceTite Manipulus Radiofrequency (RF) technology and buccal fat pad excision for enhanced neck rejuvenation promise heightened precision and efficacy in sculpting the neck and jawline. Neck liposuction, coupled with RF technology, provides controlled thermal energy for adipose tissue treatment and collagen remodeling, while buccal fat pad excision offers refined contouring of the lower face and neck. This integrated approach aims to optimize patient outcomes and advance the field of esthetic plastic surgery. METHODS: A prospective study was conducted from 2016 to 2023 on 80 consecutive patients who presented to the author's private clinic and required neck remodeling surgery for esthetic purposes. Patients were monitored and clinic appointments were scheduled at intervals of 0, 1, 3, 6 and 12 months post-treatment for evaluation. A tape measure recorded submental length at 1 and 6 months, and a satisfaction survey was administered one week before surgery and after six months. Physicians assessed improvement using a five-point scale for patient satisfaction and a four-point scale for overall improvement. RESULTS: All patients underwent successful RFAL treatment, consistently achieving satisfaction with the outcomes. The average reduction in submental length measured 23 mm during the 6-month follow-up period. Additionally, the removal of buccal fat pads played a pivotal role in facial slimming and enhancing the esthetics of the upper cheek region. CONCLUSIONS: The integration of neck liposuction with FaceTite RF technology and buccal fat pad excision offers a promising approach for enhanced neck rejuvenation and facial contouring. This combined method demonstrates heightened precision and efficacy in sculpting the neck and jawline, aiming to optimize patient outcomes and advance the field of esthetic plastic surgery. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

A comparative evaluation of the effects of 635 nm laser on cell proliferation and osteogenic differentiation of buccal fat pad mesenchymal stem cells.

The purpose of this study was to evaluate the effects of 635 nm diode laser with different powers on undifferentiated mesenchymal stem cells obtained from buccal fat pad. Human buccal fat stem cells were cultured in DMEM containing 10% FBS, penicillin, and streptomycin under 5% CO2 and 95% humidity. Cells were cultured in 96-well plate and 24 h later, laser irradiation with 635 nm diode laser was performed in four groups of 200, 300, 400, and 500 mW powers in addition to the control group with the same energy density of 4 J/cm2. MTT and flow cytometry assay was performed to evaluate cell proliferation and viability on 2 and 4 days after irradiation. Alizarin red assay and real-time PCR (OPN, OCN, ALP, and RUNX-2 genes) was performed to evaluate osteogenic differentiation. According to the MTT assay, none of the mentioned powers of 635 nm diode laser had significant effect on cell proliferation. Cells irradiated with power of 400 mW and 500 mW significantly showed a greater number of necrotic cells compared to the control group in Day 4. Cells irradiated with 300 mW power significantly exhibited a greater amount of nodule formation compared to all groups. Results of this study indicated that 635 nm diode laser with energy density of 4 J/cm2 has a positive effect inducing osteogenic differentiation when applying with a power of 300 mW in buccal fat pad mesenchymal stem cells.

The thickness change ratio and preservation ratio of the infrapatellar fat pad are related to anterior knee pain in patients following medial patellofemoral ligament reconstruction.

BACKGROUND: The infrapatellar fat pad (IPFP) lies extrasynovial and intracapsular, preserving the joint cavity and serving as a biochemical regulator of inflammatory reactions. However, there is a lack of research on the relationship between anterior knee pain (AKP) and the IPFP after medial patellofemoral ligament reconstruction (MPFLR). Pinpointing the source of pain enables clinicians to promptly manage and intervene, facilitating personalized rehabilitation and improving patient prognosis. METHODS: A total of 181 patients were included in the study. These patients were divided into the AKP group (n = 37) and the control group (n = 144). Clinical outcomes included three pain-related scores, Tegner activity score, patient satisfaction, etc. Imaging outcomes included the IPFP thickness, IPFP fibrosis, and the IPFP thickness change and preservation ratio. Multivariate analysis was used to determine the independent factors associated with AKP. Finally, the correlation between independent factors and three pain-related scores was analyzed to verify the results. RESULTS: The control group had better postoperative pain-related scores and Tegner activity score than the AKP group (P < 0.01). The AKP group had lower IPFP thickness change ratio and preservation ratio (P < 0.001), and smaller IPFP thickness (P < 0.05). The multivariate analysis revealed that the IPFP thickness change ratio [OR = 0.895, P < 0.001] and the IPFP preservation ratio [OR = 0.389, P < 0.001] were independent factors related to AKP, with a significant correlation between these factors and pain-related scores [|r| > 0.50, P < 0.01]. CONCLUSIONS: This study showed the lower IPFP change ratio and preservation ratio may be independent factors associated with AKP after MPFLR. Early detection and targeted intervention of the underlying pain sources can pave the way for tailored rehabilitation programs and improved surgical outcomes. LEVEL OF EVIDENCE LEVEL III.

Prefemoral Fat Pad Impingement Syndrome: Correlation between Ultrasonography and Magnetic Resonance Imaging.

Teaching point: Prefemoral fat pad impingement syndrome is one of the fat pad impingements of the knee and can be assessed with ultrasonography.

Therapeutic potential of dedifferentiated fat cells in a rat model of osteoarthritis of the knee.

Introduction: Mature adipocyte-derived dedifferentiated fat cells (DFATs) represent a subtype of multipotent cells that exhibit comparable phenotypic and functional characteristics to adipose-derived stem cells (ASCs). In this study, we assessed the chondroprotective properties of intra-articularly administrated DFATs in a rat model of osteoarthritis (OA). We also investigated in vitro the expression of anti-inflammatory and chondroprotective genes in DFATs prepared from the infrapatellar fat pad (IFP) and subcutaneous adipose-tissue (SC) of human origin. Methods: In the cell transplantation experiment, rats were assigned to the DFAT and Control group (n = 10 in each group) and underwent anterior cruciate ligament transection (ACLT) accompanied by medial meniscus resection (MMx) to induce OA. One week later, they received intra-articular injections of 1 × 106 DFATs (DFAT group) or PBS (control group) four times, with a weekly administration frequency. Macroscopic and microscopic evaluations were conducted five weeks post-surgery. In the in vitro experiments. DFATs derived from the IFP (IFP-DFATs) and SC (SC-DFATs) were prepared from donor-matched tissue samples (n = 3). The gene expression of PTGS2, TNFAIP6, PRG4, BMP2, and BMP6 under TNF-α or IFN-γ stimulation in these cells was evaluated using RT-PCR. Furthermore, the effect of co-culturing synovial fibroblasts with DFATs on the gene expression of ADAMTS4 and IL-6 were evaluated. Results: Intra-articular injections of DFATs significantly inhibited cartilage degeneration in the rat OA model induced by ACLT and MMx. RT-PCR analysis revealed that both IFP-DFATs and SC-DFATs upregulated the expression of genes involved in immune regulation, anti-inflammation, and cartilage protection such as PTGS2, TNFAIP6, and BMP2, under stimulation by inflammatory cytokines. Co-culture with DFATs suppressed the expression of ADAMTS4 and IL6 in synovial fibroblasts. Conclusions: The intra-articular injection of DFATs resulted in chondroprotective effects in the rat OA model. Both SC-DFATs and IFP-DFATs induced the expression of anti-inflammatory and chondroprotective genes in vitro. These results indicate that DFATs appear to possess therapeutic potential in inhibiting cartilage degradation and could serve as a promising cellular resource for OA treatment.

Unveiling rarity: Myoepithelioma in the minor salivary gland of buccal mucosa - A case report.

INTRODUCTION: Tumours of salivary glands are rare and have various histo-pathological subtypes. Myoepitheliomas were first classified by Sheldon et al. and the criterion to classify or diagnose it was first defined by Barnes et al. and Sciubba and Brannon. Myoepithelioma accounts for less than 1 % of all salivary gland tumours, 40 % of these tumours occur in the parotid gland while 21 % occur in the minor salivary glands. A case of myoepithelioma of a minor salivary gland of the cheek is described, emphasizing the problems of the differential diagnosis. PRESENTATION OF THE CASE: A 40-year-old female reported to the department with a complaint of a cheek bite on her right side for a few months. The physical examination showed a presence of lobulated whitish mucosa on the right buccal mucosa at the level of the occlusal plane, on palpation it revealed a non-painful mass approximately 1.5 cm in radius, mobile to bimanual palpation. An excisional biopsy was performed under local anaesthesia. Microscopic and immunohistochemistry confirmed the tumour to be a myoepithelioma of a minor salivary gland with the absence of definitive features of malignancy. DISCUSSION: Due to their infrequency and multiplicity of histopathology, myoepitheliomas present difficulties in diagnosis. Cellular varieties can be misdiagnosed as malignancies. A key to determining diagnostic criteria for myoepitheliomas is to study cellular morphology, cytoplasmic filament expression, and ultrastructural features of the tumour and apply this information to defining myoepitheliomas. CONCLUSION: Myoepitheliomas are rare tumours, utilization of immunohistochemical staining and electron microscopy are useful tools for the diagnosis of myoepitheliomas to ensure proper treatment and follow-up.

A Novel Infrapatellar Fat Pad Preservation Technique in Total Knee Arthroplasty Reduced Postoperative Pain and Wound Complications.

OBJECTIVE: The management of the infrapatellar fat pad (IPFP) during total knee arthroplasty (TKA) remains controversial. This study aimed to evaluate a novel IPFP preservation technique-"the medially pedicled IPFP flap"-for reducing postoperative pain, wound complications, and improving functional recovery after TKA. METHODS: A retrospective analysis was conducted on TKA cases at our institution from 2018 to 2021, including those with IPFP preservation (medially pedicled flap) versus IPFP complete resection. Patient demographics, perioperative parameters (blood loss, operative time, length of hospital stay, visual analogue scale [VAS] score, white cell count [WBC], C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], and wound oozing), and postoperative follow-up data (VAS, Knee Society [KSS], or Knee Society functional assessment [KSFA] scores) were compared between groups. Independent sample t-tests were used to compare continuous data and chi-squared tests were used to compare categorical data between groups. RESULTS: Six hundred thirty patients were included, with 278 in the medial pedicled IPFP flap group (preservation group) and 352 in the IPFP resection group (resection group). The operative time was significantly shorter in the preservation versus resection group (125.5 ± 23.2 vs 130.3 ± 28.7 mins, p = 0.03), as was the length of hospital stay (8.4 ± 2.7 vs 9.2 ± 2.3 days, p < 0.01). Regarding pain, the preservation group had significantly lower VAS scores on postoperative day 2 (2.0 ± 0.8 vs 2.4 ± 1.2, p < 0.001) and day 3 (1.5 ± 0.5 vs 1.8 ± 1.0, p < 0.001). CRP and ESR levels on postoperative day 5 were also significantly lower in the preservation group. Wound oozing rates were significantly lower in the preservation versus resection group (0.7% vs 2.8%, p = 0.04). No significant differences existed in VAS, KSS, or KSFA scores at the last follow-up. CONCLUSION: The novel IPFP preservation technique significantly improved surgical exposure, shortened operative time and length of hospital stay. It also reduced wound pain and oozing compared to IPFP resection.

Effect of isometric quadriceps exercise on local microcirculation of the infrapatellar fat pad in female patients with knee osteoarthritis.

OBJECTIVE: To elucidate the local microcirculation of the infrapatellar fat pad (IFP) in patients with knee osteoarthritis (KOA) by determining the changes in IFP hardness and hemoglobin concentration during isometric quadriceps exercise (IQE). DESIGN: In this observational cross-sectional study, patients diagnosed with bilateral KOA were included in the KOA group (30 knees), healthy older adults in the control group (20 knees), and younger adults in the young group (20 knees). Ultrasonography was performed at rest and during IQE to measure IFP hardness based on shear wave velocity. Near-infrared spectroscopy was performed to measure oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) in the IFP before (Baseline), during (IQE task), and after IQE (Post). IFP hardness and O2Hb, HHb, and cHb concentration were analyzed using a linear mixed model for the groups and measurement points. RESULTS: During IQE, IFP hardness changes were significantly less in the KOA group than in the other groups (KOA: 95 % confidence intervals (CIs) [-0.854, 0.028]; control: 95 % CI [-0.941, -0.341]; and young: 95 % CI [-2.305, -1.706]). In the KOA group, O2Hb concentration exhibited no significant changes at Post compared with Baseline; however, significant changes were observed in the other groups (KOA: 95 % CI [-1.176, 0.423]; control: 95 % CI [-1.452, -0.276]; and young: 95 % CI [-4.062, -2.102]). CONCLUSIONS: During IQE, changes in hardness and hemoglobin concentration in the IFP were not significant in the KOA group, suggesting impaired local microcirculation of the IFP.

Surgical sealant using free pericardial fat pad with fibrin glue and polyglycolic acid sheets for secondary spontaneous pneumothorax: a novel technique.

We report on the "Triple-FP technique," a novel surgical approach for secondary spontaneous pneumothoraces, which combines a free pericardial fat pad, fibrin glue, and polyglycolic acid sheets. In our experience with 13 patients suffering from secondary spontaneous pneumothoraces, this method effectively prevented postoperative air leaks and re-operations. The technique includes the following steps: (1) harvesting free pericardial fat; (2) suturing around the lung parenchymal defect with the needles and thread left outside the thoracic cavity; (3) ensuring contact between the mediastinal pleural side of the fat and the lung; (4) applying fibrin glue to both the lung and fat before suturing; (5) securing the fat to the lung via the suture thread, reinforced with fibrin glue; and (6) stabilization with polyglycolic acid sheets and additional fibrin glue. This innovative technique is a reliable and effective treatment strategy for secondary spontaneous pneumothoraces, especially for patients with fragile lung tissue.

Role of joint adipose tissues in osteoarthritis.

Osteoarthritis (OA) is the most common musculoskeletal disease, without any curative treatment. Obesity being the main modifiable risk factor for OA, much attention focused on the role of adipose tissues (AT). In addition to the involvement of visceral and subcutaneous AT via systemic ways, many arguments also highlight the involvement of local AT, present in joint tissues. Local AT include intra-articular AT (IAAT), which border the synovium, and bone marrow AT (BMAT) localized within marrow cavities in the bones. This review describes the known features and involvement of IAAT and BMAT in joint homeostasis and OA. Recent findings evidence that alteration in magnetic resonance imaging signal intensity of infrapatellar fat pad can be predictive of the development and progression of knee OA. IAAT and synovium are partners of the same functional unit; IAAT playing an early and pivotal role in synovial inflammation and fibrosis and OA pain. BMAT, whose functions have only recently begun to be studied, is in close functional interaction with its microenvironment. The volume and molecular profile of BMAT change according to the pathophysiological context, enabling fine regulation of haematopoiesis and bone metabolism. Although its role in OA has not yet been studied, the localization of BMAT, its functions and the importance of the bone remodelling processes that occur in OA argue in favour of a role for BMAT in OA.

Removal of the infrapatellar fat pad and associated synovium benefits female guinea pigs in the Dunkin Hartley model of idiopathic osteoarthritis.

Background: Several tissues contribute to the onset and advancement of knee osteoarthritis (OA). One tissue type that is worthy of closer evaluation, particularly in the context of sex, is the infrapatellar fat pad (IFP). We previously demonstrated that removal of the IFP had short-term beneficial effects for a cohort of male Dunkin-Hartley guinea pigs. The present project was designed to elucidate the influence of IFP removal in females of this OA-prone strain. It was hypothesized that resection of the IFP would reduce the development of OA in knees of a rodent model predisposed to the disease. Methods: Female guinea pigs (n=16) were acquired at an age of 2.5 months. Surgical removal of the IFP and associated synovium complex (IFP/SC) was executed at 3 months of age. One knee had the IFP/SC resected; a comparable sham surgery was performed on the contralateral knee. All animals were subjected to voluntary enclosure monitoring and dynamic weight-bearing, as well as compulsory treadmill-based gait analysis monthly; baseline data was collected prior to surgery. Guinea pigs were euthanized at 7 months. Knees from eight animals were evaluated via histology, mRNA expression, and immunohistochemistry (IHC); knees from the remaining eight animals were allocated to microcomputed tomography (microCT), biomechanical analyses (whole joint testing and indentation relaxation testing), and atomic absorption spectroscopy (AAS). Results: Fibrous connective tissue (FCT) replaced the IFP/SC. Mobility/gait data indicated that unilateral IFP/SC removal did not affect bilateral hindlimb movement. MicroCT demonstrated that osteophytes were not a significant feature of OA in this sex; however, trabecular thickness (TbTh) in medial femorae decreased in knees containing the FCT. Histopathology scores were predominantly influenced by changes in the lateral tibia, which demonstrated that histologic signs of OA were increased in knees containing the native IFP/SC versus those with the FCT. Similarly, indentation testing demonstrated higher instantaneous and equilibrium moduli in the lateral tibial articular cartilage of control knees with native IFPs. AAS of multiple tissue types associated with the knee revealed that zinc was the major trace element influenced by removal of the IFP/SC. Conclusions: Our data suggest that the IFP/SC is a significant component driving knee OA in female guinea pigs and that resection of this tissue prior to disease has short-term benefits. Specifically, the formation of the FCT in place of the native tissue resulted in decreased cartilage-related OA changes, as demonstrated by reduced Osteoarthritis Research Society International (OARSI) histology scores, as well as changes in transcript, protein, and cartilage indentation analyses. Importantly, this model provides evidence that sex needs to be considered when investigating responses and associated mechanisms seen with this intervention.

Association between quadriceps fat pad edema and patellofemoral osteoarthritis: a quantitative Q-Dixon-based magnetic resonance imaging (MRI) analysis.

Background: Anterior knee pain (AKP) is a common symptom of patellofemoral osteoarthritis (PFOA). There is limited prospective evidence supporting the relationships between patellofemoral maltracking parameters, AKP, and PFOA. Thus, this prospective cross-sectional study aimed to determine the association between quadriceps fat pad (QFP) edema and patellofemoral maltracking in patients with chronic AKP and to evaluate the feasibility and diagnostic performance of a PFOA assessment using fat fraction (FF) and T2* based on Q-Dixon. Methods: This was a cross-sectional study with prospective data collection. Patients with chronic AKP were recruited from an orthopedic outpatient magnetic resonance imaging (MRI) waiting room at Shanghai Tongren Hospital between November 1, 2022, and April, 30, 2023. Exclusion criteria included age of <18 years, knee trauma, major internal derangement, prior surgery/arthroscopy, pre-existing joint diseases, and contraindications to MRI. MRI was performed using a 3.0-T instrument, and patellofemoral maltracking parameters were measured. Patellofemoral feature-relevant items, including patellar cartilage defects, patellar bone marrow lesions (BMLs), patellar osteophytes, anterior femoral osteophytes, Hoffa synovitis, and synovitis-effusion, from the semi-quantitative MRI Osteoarthritis Knee Score (MOAKS) were measured. The Anterior Knee Pain Scale (AKPS) was used to assess pain and function. FF/T2* measurement differences between groups and their associations with maltracking metrics, osteoarthritis grading based on the Iwano grading system, MOAKS, and AKPS, were investigated. Based on Iwano grading, the participants were categorized as having no-PFOA (n=40), mild PFOA (n=40), and advanced PFOA (n=40). Chi-squared and one-way analysis of variance were used to assess potential differences between the groups. Spearman's correlation test was used to analyze the correlation between the morphological parameters, AKPS, Iwano grade, MOAKS, and MRI quantitative values. Receiver operating characteristic (ROC) curves assessed the area under the curve (AUC), sensitivity, and specificity of quantitative values for distinguishing PFOA from no-PFOA. Results: Among the 120 included patients, those in the mild (86.2±8.5) and advanced (83.9±9.5) PFOA groups had significantly lower AKPS scores than those in the no-PFOA group (88.8±7.3) (P=0.03). The mean FF and T2* values of the QFP were significantly higher in the no-PFOA group than those in the mild and advanced PFOA groups (P<0.001 for FF and P=0.02 for T2*). Quantitative data on the QFP and patellofemoral maltracking parameters showed no association. FF (r=-0.686, P<0.001) and T2* (r=-0.314, P=0.008) showed a negative correlation with the Iwano grade. The AUCs for PFOA diagnosis were 0.906 [95% confidence interval (CI), 0.853-0.960] (FF) and 0.744 (95% CI, 0.657-0.831) (T2*). Conclusions: QFP FF and T2* were not associated with patellofemoral maltracking parameters but with increased PFOA in patients with AKP, suggesting that QFP abnormalities play a role in PFOA. Therefore, a quantitative QFP assessment (FF and T2*) based on Q-Dixon technology could be a convenient and reliable new imaging biomarker for PFOA severity during clinical diagnosis, treatment, and follow-up.

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.