Arthroscopic Treatment of Infrapatellar Fat Pad Impingement between the Patella and Femoral Trochlea: Comparison of the Clinical Outcomes of Partial and Subtotal Resection

Metabolic Functions of the Infrapatellar Fat Pad: Implications for Knee Health and Pathology

» Despite being historically viewed as a vestigial structure, the infrapatellar fat pad (IPFP) is now recognized as a metabolically active structure, influencing knee health through cytokine production and metabolic pathways.» With distinct anatomical regions, the IPFP contains diverse cell types including adipocytes, fibroblasts, and immune cells, influencing its functional roles, pathology, and contributions to knee disorders.» The IPFP acts as an endocrine organ by releasing adipokines such as adiponectin, leptin, and tumor necrosis factor α, regulating energy balance, immune responses, and tissue remodelling, with implications for knee joint health.» The IPFP's metabolic interactions with neighboring tissues influence joint health, clinical conditions such as knee pain, osteoarthritis, postoperative complications, and ganglion cysts, highlighting its therapeutic potential and clinical relevance.» Understanding the multifaceted metabolic role of the IPFP opens avenues for collaborative approaches that integrate orthopaedics, endocrinology, and immunology to develop innovative therapeutic strategies targeting the intricate connections between adipokines, joint health, and immune responses.

Medial Patellar Plica Thickness as a Morphologic Predictor of the Medial Patellar Plica Syndrome

OBJECTIVE

The aim of this study was to evaluate the association between medial patellar plica (MPP) syndrome and the morphological features of the MPP, including length, width, and thickness, on knee magnetic resonance imaging (MRI).

MATERIALS AND METHODS

From 2018 to 2022, 167 patients diagnosed with isolated MPP syndrome based on both MRI and arthroscopic findings were included in the "study group" and 226 patients without knee pathology on both MRI and physical examination were included in the "control group." Finally, 393 patients (mean age, 38.9 ± 5.7 years) with 405 knee MRI examinations were included. Morphological MR features of MPP were assessed, including width, length, and thickness. Multivariate regression and receiver operating characteristic analyses were performed to identify the factors associated with MPP syndrome.

RESULTS

The mean thickness of MPP was significantly higher in the study group than control group (2.3 ± 0.5 mm vs 1.0 ± 0.8 mm, P < 0.001). Moreover, on multivariate analysis, MPP thickness was the only significant factor associated with MPP syndrome (odds ratio, 6.452; 95% confidence interval, 0.816-15.073; P = 0.002). On receiver operating characteristic analysis, thickness ≥1.8 mm was estimated as the optimal cutoff for predicting MPP syndrome with sensitivity of 75.9%, specificity of 65.4%, and area under the curve of 0.727 (95% confidence interval, 0.667-0.788; P < 0.001).

CONCLUSIONS

Measurement of MPP thickness on MRI could be a morphological predictor of MPP syndrome.

Is the patient aware of the difference between resurfaced and nonresurfaced patella after bilateral total knee arthroplasty? A systematic review of simultaneous bilateral randomized trials

Purpose

The optimal practice of patellar management in total knee arthroplasty (TKA) remains controversial. This systematic review was conducted to compare patella-related (1) patient-reported outcome measures (PROMs), (2) clinical outcomes, and (3) reoperation rates after TKA with patellar resurfacing (PR) and nonresurfacing (NPR) in single patients undergoing bilateral patellar procedures during simultaneous bilateral TKA.

Methods

This review included prospective bilateral randomized trials investigating patella-related PROMs, clinical outcomes, and reoperation (secondary resurfacing and patellar component revision) and other patella-related complications in single patients undergoing randomly assigned PR and NPR during bilateral TKA.

Results

Six studies were included. There was no difference in PROMs between PR and NPR in five studies, whereas PR was found to be superior to NPR in one study. Five studies reported similar functional outcomes and complication rates between PR and NPR, while one study found better clinical outcomes and a lower complication rate in PR. Between-group secondary resurfacing and patellar revision rates were similar in all studies.

Conclusions

The majority of patients who underwent bilateral patellar procedures could not tell the difference between PR and NPR following bilateral TKA. There were no differences in clinical outcomes or reoperation and complication rates between PR and NPR. No evidence was found to support routine PR.

Level of evidence: Therapeutic Level 1

Increased signal intensity, not volume variation of infrapatellar fat pad in knee osteoarthritis: A cross-sectional study based on high-resolution magnetic resonance imaging

BACKGROUND

Infrapatellar fat pad (IPFP) is regarded as an essential knee tissue involved in osteoarthritis (OA) for its potential structural-related or metabolism-related function. This cross-sectional study aims to identify which part is more related to OA.

METHODS

Patients with knee OA (n = 53) and healthy controls (n = 54) were prospectively recruited. Based on high-resolution magnetic resonance imaging with a slice thickness of only 0.35 mm, IPFP structural-related parameters (volume and maximal area), metabolism-related parameter (signal), degeneration indicators, and patellar maltracking indicators (patellar translation, patellofemoral angle, and Insall-Salvati ratio) were measured. IPFP volume (maximal area, and signal) was compared between healthy controls and OA patients. The level of significance for all comparisons was set as .05.

RESULTS

OA patients had higher IPFP signal (672.9 ± 136.9 vs 567.3 ± 63.6, p = .009), but no significant difference in IPFP volume or maximal area compared with healthy controls. In healthy controls, IPFP signal was positively associated with age (β = 1.481; 95% CI: 0.286-2.676; p = .018); IPFP maximal area was positively related to Insall-Salvati ratio (β = 0.001; 95% CI: 0.0003-0.0017; p = .039), but not associated with patellar translation and patellofemoral angle. In OA patients, IPFP signal was positively associated with cartilage loss (β = 0.005; 95% CI: 0.003-0.007; p = .013); no correlation between knee pain and IPFP volume or maximal area was observed.

CONCLUSIONS

The metabolism-related function of IPFP, which can be reflected by the IPFP signal, might play a more critical role in OA progression than its structural function.

The impact of infrapatellar fat pad excision versus preservation after total knee replacement on anterior knee pain, functional outcome and patellar height: Randomized controlled trial

Introduction

Although better surgical exposure is encountered with the excision of infrapatellar pad of fat (IPPF) during total knee replacement (TKR), some studies showed an increase in anterior knee pain and other specific complications associated with such a step. The purpose of this study was to add in literature a new comparison between IPPF excision and preservation during TKR, focusing on the anterior knee pain, functional range, oxford knee score and patellar height through a randomized clinical trial

Methods

This prospective randomized study was conducted from 2016 to 2019 on 90 patients with knee osteoarthritis treated with elective primary TKA by same surgeons at one hospital with the same implant design with a mean follow up of 18 month. Patients were randomized into two groups: one group including patients with IPPF complete excision and the other group include patients with IPPF preservation. No patella resurfacing was done. Pre and postoperative anterior knee pain was recorded and compared using VAS score in addition to Oxford knee score.

Results

At 6 months follow-up, 10 knees and 14 knees (27%) had anterior aching discomfort with a mean postoperative extension were −5.3 and −5.2 in IPPF preservation and excision group patients, respectively. There was no statistically significant differences between both groups regarding anterior knee pain, range of motion, oxford knee score or patellar height measurement through the follow up period. No patellar complications were recorded in all cases.

Conclusion

Although Infrapatellar fat pad excision in TKA resulted in a minor increase in number of patients with postoperative anterior knee pain, it was of no statistically significant difference. Hence, whenever a better surgical exposure is needed, IPPF excision should be considered. Additional large scale randomized studies should be added to the calling literature for more result validation and guidelines formulation.

Patella-patellar tendon angle in relation to the medial patellar plica syndrome, chondromalacia patella, and infrapatellar fat pad syndrome

The patella-patellar tendon angle (PPTA) assessing the sagittal patellar tilt was reported to be related with anterior knee pain. Herein, clinical effect of PPTA in patients with medial patellar plica (MPP) syndrome, chondromalacia patella, and infrapatellar fat pad (IPFP) syndrome, the most common causes of anterior knee pain, was evaluated. In this retrospective study, 156 patients with anterior knee pain who underwent magnetic resonance imaging (MRI) and arthroscopic surgery that confirmed isolated MPP syndrome, chondromalacia patella, or IPFP syndrome from June 2011 to January 2021 were included in the study group and 118 patients without knee pathology on MRI during the same period were included in the control group. The PPTA was measured on knee MRI and compared between the two groups. A receiver operating characteristic (ROC) analysis was used to evaluate the value of PPTA for predicting the risk of patellofemoral joint disorder. The mean PPTA was significantly smaller in study group (138.1 ± 4.2°) than control group (142.1 ± 4.3°) (p < 0.001). However, there was no significant difference in PPTA among the patients with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, the ROC analysis revealed that the area under curve, sensitivity, and specificity for predicting the risk of patellofemoral joint disorders were 0.696, 70.3% and 57.6%, respectively, at a PPTA cutoff of 138.3°. Therefore, the smaller PPTA may be associated with MPP syndrome, chondromalacia patella, and IPFP syndrome. Furthermore, PPTA could be a predictive factor for the risk of patellofemoral joint disease in patients with anterior knee pain.

Patella-patellar tendon angle decreases in patients with infrapatellar fat pad syndrome and medial patellar plica syndrome

PURPOSE

Infrapatellar fat pad (IPFP) syndrome and medial patellar plica (MPP) syndrome are two recognized causes of anterior knee pain. However, diagnosing these syndromes is challenging without arthroscopic examination. The aim of this study was to evaluate sagittal patellar tilt in patients with IPFP syndrome or MPP syndrome by measuring the patella-patellar tendon angle (PPTA) in affected patients.

METHODS

Eighty-three patients with anterior knee pain who underwent diagnostic arthroscopy that confirmed isolated IPFP or MPP syndrome from 2011 to 2016 were included in this retrospective study. Patients were divided into Group A (IPFP syndrome, n = 44) and Group B (MPP syndrome, n = 39). The control group included 78 patients without knee pathology who underwent magnetic resonance imaging (MRI) of the knee during the study period. Radiographic measurements, including PPTA, IPFP area, patellar height, axial patellar alignment, patellar tilt, sulcus angle, and lateral trochlear inclination, were made on MRI images by two experienced sports medicine orthopedists.

RESULTS

The mean PPTA in each knee-pathology group was significantly smaller than that in the control group (Group A: 137.3° ± 4.9°; Group B: 138.1° ± 3.2°; control group, 141.4° ± 2.9°). There was no significant difference between groups for any other radiographic parameter evaluated.

CONCLUSION

The PPTA was significantly smaller in patients with IPFP syndrome or MPP syndrome than in healthy controls. Therefore, sagittal patellar tilt should be included in the routine evaluation of patients with anterior knee pain. Evaluation of PPTA may help to diagnose IPFP syndrome or MPP syndrome.

LEVEL OF EVIDENCE

Level IV.