The role of infrapatellar fat pad resection in total knee arthroplasty

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.

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.

Early removal of the infrapatellar fat pad/synovium complex beneficially alters the pathogenesis of moderate stage idiopathic knee osteoarthritis in male Dunkin Hartley guinea pigs

BACKGROUND

The infrapatellar fat pad (IFP) is the largest adipose deposit in the knee; however, its contributions to the homeostasis of this organ remain undefined. To determine the influence of the IFP and its associated synovium (IFP/synovium complex or IFP/SC) on joint health, this study evaluated the progression of osteoarthritis (OA) following excision of this unit in a rodent model of naturally-occurring disease.

METHODS

Male Dunkin-Hartley guinea pigs (n=18) received surgical removal of the IFP in one knee at 3 months of age; contralateral knees received sham surgery as matched internal controls. Mobility and gait assessments were performed prior to IFP/SC removal and monthly thereafter. Animals were harvested at 7 months of age. Ten set of these knees were processed for microcomputed tomography (microCT), histopathology, transcript expression analyses, and immunohistochemistry (IHC); 8 sets of knees were dedicated to microCT and biomechanical testing (material properties of knee joints tissues and anterior drawer laxity).

RESULTS

Fibrous connective tissue (FCT) developed in place of the native adipose depot. Gait demonstrated no significant differences between IFP/SC removal and contralateral hindlimbs. MicroCT OA scores were improved in knees containing the FCT. Quantitatively, IFP/SC-containing knees had more osteophyte development and increased trabecular volume bone mineral density (vBMD) in femora and tibiae. Histopathology confirmed maintenance of articular cartilage structure, proteoglycan content, and chondrocyte cellularity in FCT-containing knees. Transcript analyses revealed decreased expression of adipose-related molecules and select inflammatory mediators in FCTs compared to IFP/SCs. This was verified via IHC for two key inflammatory agents. The medial articular cartilage in knees with native IFP/SCs showed an increase in equilibrium modulus, which correlated with increased amounts of magnesium and phosphorus.

DISCUSSION/CONCLUSION

Formation of the FCT resulted in reduced OA-associated changes in both bone and cartilage. This benefit may be associated with: a decrease in inflammatory mediators at transcript and protein levels; and/or improved biomechanical properties. Thus, the IFP/SC may play a role in the pathogenesis of knee OA in this strain, with removal prior to disease onset appearing to have short-term benefits.

Effects of infrapatellar fat pad preservation versus resection on clinical outcomes after total knee arthroplasty in patients with knee osteoarthritis (IPAKA): study protocol for a multicentre, randomised, controlled clinical trial

INTRODUCTION

The infrapatellar fat pad (IPFP) is commonly resected during total knee arthroplasty (TKA) for better exposure. However, our previous studies have suggested that IPFP size was protective against, while IPFP signal intensity alteration was detrimental on knee symptoms and structural abnormalities. We hypothesise that an IPFP with normal qualities, rather than abnormal qualities, should be preserved during TKA. The aim of this study is to compare, over a 1-year period, the postoperative clinical outcomes of IPFP preservation versus resection after TKA in patients with normal or abnormal IPFP signal intensity alteration on MRI.

METHODS AND ANALYSIS

Three hundred and sixty people with end-stage knee osteoarthritis and on the waiting list for TKA will be recruited and identified as normal IPFP quality (signal intensity alteration score ≤1) or abnormal IPFP quality (signal intensity alteration score ≥2). Patients in each hospital will then be randomly allocated to IPFP resection group or preservation group. The primary outcomes are the summed score of self-reported Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS subscales assessing function in daily activities and function in sport and recreation. Secondary endpoints will be included: KOOS subscales (pain, symptoms and quality of life), Knee Society Score, 100 mm Visual Analogue Scale (VAS) Pain, timed up-and-go test, patellar tendon shortening, 100 mm VAS self-reported efficacy of reduced pain and increased quality of life, and Insall-Salvati index assessed on plain X-ray. Adverse events will be recorded. Intention-to-treat analyses will be used.

ETHICS AND DISSEMINATION

The study is approved by the local Medical Ethics Committee (Zhujiang Hospital Ethics Committee, reference number 2017-GJGBK-001) and will be conducted according to the principle of the Declaration of Helsinki (64th, 2013) and the Good Clinical Practice standard, and in compliance with the Medical Research Involving Human Subjects Act . Data will be published in peer-reviewed journals and presented at conferences, both nationally and internationally.

TRIAL REGISTRATION NUMBER

This trial was registered at Clinicaltrial.gov website on 19 October 2018 with identify number NCT03763448.

Infrapatellar Fat Pad and Knee Osteoarthritis

Osteoarthritis is the most prevalent arthritis typically characterized by degradation of cartilage. However, its pathogenesis is not fully understood. Currently, osteoarthritis is best considered a disease of the whole "joint organ". Infrapatellar fat pad (IFP), an adipose tissue near synovium, is now attaching importance to researchers for its inflammatory phenotype. In this narrative review, a large body of evidence has been gathered for the involvement of IFP in the development of knee osteoarthritis. Additionally, the underlying mechanisms of how IFP can be involved in this process have been proposed. However, further investigations are needed to better understand its precise role in this process and its underlying mechanism, and beyond that, to develop new strategies to slow down the degenerative process and explore an effective and timely diagnosis of the disease.

Daily and short-term application of joint movement for the prevention of infrapatellar fat pad atrophy due to immobilization

[Purpose] To mobilize the knee joint during cast fixation and to determine whether infrapatellar fat pad changes can be prevented. [Materials and Methods] We randomly allocated Wistar rats into 3 groups as follows: normal group, raised in normal conditions (n=5); contracture group, immobilized with cast fixation (n=5); and prevention group, treated with joint movement during immobilization (n=5). We immobilized the right hindlimb using cast fixation. Joint movement in the prevention group was accomplished by repeatedly pulling the right hindlimb caudally and then returning the leg to the bent position for 10 minutes every day for 2 weeks. We used a metronome to maintain a constant speed, with one set lasting 2 seconds (1-second traction and 1-second return). [Results] The contracture group had adipose cells of various sizes and fibrosis in the infrapatellar fat pad. These changes were also found in milder forms in the prevention group. We found significant differences in the cross section of adipose cells and in knee extension restriction between the groups. [Conclusion] Promoting joint movement may not only have a therapeutic effect on adipose cells but also a preventative effect.

Minimally invasive total knee replacement: techniques and results

In this review, we outlined the definition of minimally invasive surgery (MIS) in total knee replacement (TKR) and described the different surgical approaches reported in the literature. Afterwards, we went through the most recent studies assessing MIS TKR. Next, we searched for potential limitations of MIS knee replacement and tried to answer the following questions: Are there selective criteria and specific patient selection for MIS knee surgery? If there are, then what are they? After all, a discussion and conclusion completed this article. There is certainly room for MIS or at least less invasive surgery for appropriate selected patients. Nonetheless, there are differences between approaches. Mini-medial parapatellar is easy to master, quick to perform and potentially extendable, whereas mini-subvastus and mini-midvastus are trickier and require more caution related to risk of haematoma and vastus medialis oblique (VMO) nerve damage. Current evidence on the safety and efficacy of mini-incision surgery for TKR does not appear fully adequate for the procedure to be used without special arrangements for consent and for audit or continuing research. There is an argument that a sudden jump from standard TKR to MIS TKR, especially without computer assistance such as navigation, patient-specific instrumentation or robotic, may breach a surgeon's duty of care towards patients because it exposes patients to unnecessary risks. As a final point, more evidence is required on the long-term safety and efficacy of this procedure which will give objective shed light on real benefits of MIS TKR.

Systemic and Local Adipose Tissue in Knee Osteoarthritis

Osteoarthritis is a common chronic joint disorder affecting older people. The knee is the major joint affected. The symptoms of osteoarthritis include limited range of motion, joint swelling, and pain causing disability. There are no disease modifying drugs available, and treatments are mainly focused on pain management. Total knee replacement performed at the end stage of the disease is considered the only cure available. It has been found that obese people have an increased risk to develop not only knee but also hand osteoarthritis. This supports the concept that adipose tissue might be related to osteoarthritis not only through overloading. As matter of fact, obesity induces a low grade systemic inflammatory state characterized by the production and secretion of several adipocytokines that may have a role in osteoarthritis development. Furthermore, hypertension, impaired glucose, and lipid metabolism, which are comorbidities associated with obesity, have been shown to alter the joint tissue homeostasis. Moreover, infrapatellar fat pad in the knee has been demonstrated to be a local source of adipocytokines and potentially contribute to osteoarthritis pathogenesis. Here, we discuss the role of systemic and local adipose tissue in knee osteoarthritis. J. Cell. Physiol. 232: 1971-1978, 2017. © 2016 Wiley Periodicals, Inc.