Effects of Viscosupplementation on Quality of Knee Joint Arthrokinematic Motion Analyzed by Vibroarthrography

Lesion Size Location Dependency on Maximum Pressure in Osteochondral Defects: Experiments and Finite-Element Analysis

Background

Osteochondral defects (OCDs) in the knee joint have significant clinical implications, particularly regarding contact pressures and pressure distribution. Understanding how these factors are influenced by defect size and location is crucial for developing effective therapeutic strategies.

Purpose/Hypothesis

The purpose of this study was to investigate the impact of defect size and location on contact pressures and pressure distribution in the knee joint. It was hypothesized that an increase in defect size would result in elevated contact pressures and alterations in pressure distribution, with specific variations related to defect location.

Study Design

Descriptive laboratory study.

Methods

The study utilized 6 cadaveric knees, including the patella and fibula, subjected to controlled compressive loading for measuring contact pressures. Simultaneously, computed tomography-based models were created for finite-element analysis (FEA) to investigate the impact of varying defect sizes and locations on contact pressures and pressure distribution in the knee joint, excluding the patellofemoral joint. The study employed analysis of variance to assess contact pressure and defect size association. Comparison between medial and lateral femoral condyles at full extension and 30° flexion angle was performed, followed by post hoc testing. Fisher exact test analyzed peak pressure point location and defect size, categorizing them into medial and lateral.

Results

An increase in defect size corresponded with heightened contact pressures on both medial and lateral femoral condyles at full extension (P = .013 for medial and P = .024 for lateral). However, this correlation did not yield significant differences at 30° of flexion (P = .674 for medial and P = .333 for lateral). During mechanical testing, the highest pressures occurred near 5 mm defect dimensions. FEAs showed a significant increase in pressure and circumferential-edge stress with 7-mm defects. Peak contact pressure points shifted laterally with more significant defects.

Conclusion

Our study demonstrated the impact of defect size, location, and alignment on knee joint contact pressures. Intervening promptly with defects exceeding 3 mm is crucial, as significant stress levels manifest beyond this threshold. Significant increases in contact pressures were noted with larger defect sizes, particularly between 3 and 10 mm at full extension. Peak pressure points shifted with defect size increments, and alignment variations showed minimal stress variation at 30° compared with 0°. FEA validated increasing contact pressures up to 7 mm defect size, beyond which pressures stabilized or slightly decreased. A concentrated pressure distribution on the medial side was observed. These findings inform our understanding of the biomechanical implications of OCDs.

Clinical Relevance

In the field of sports medicine, this research offers valuable insights to clinicians and researchers, elucidating key factors influencing knee joint health and the potential consequences of OCDs.

Poly(ethylene Glycol) Methyl Ether Methacrylate-Based Injectable Hydrogels: Swelling, Rheological, and In Vitro Biocompatibility Properties with ATDC5 Chondrogenic Lineage

Here, we present the synthesis of a series of chemical homopolymeric and copolymeric injectable hydrogels based on polyethylene glycol methyl ether methacrylate (PEGMEM) alone or with 2-dimethylamino ethyl methacrylate (DMAEM). The objective of this study was to investigate how the modification of hydrogel components influences the swelling, rheological attributes, and in vitro biocompatibility of the hydrogels. The hydrogels' networks were formed via free radical polymerization, as assured by 1H nuclear magnetic resonance spectroscopy (1H NMR). The swelling of the hydrogels directly correlated with the monomer and the catalyst amounts, in addition to the molecular weight of the monomer. Rheological analysis revealed that most of the synthesized hydrogels had viscoelastic and shear-thinning properties. The storage modulus and the viscosity increased by increasing the monomer and the crosslinker fraction but decreased by increasing the catalyst. MTT analysis showed no potential toxicity of the homopolymeric hydrogels, whereas the copolymeric hydrogels were toxic only at high DMEAM concentrations. The crosslinker polyethylene glycol dimethacrylate (PEGDMA) induced inflammation in ATDC5 cells, as detected by the significant increase in nitric oxide synthase type II activity. The results suggest a range of highly tunable homopolymeric and copolymeric hydrogels as candidates for cartilage regeneration.

Engineering of Viscosupplement Biomaterials for Treatment of Osteoarthritis: A Comprehensive Review

Osteoarthritis (OA) is a progressive degenerative disease that causes severe pain and functional limitation, especially during locomotion. It is the most common arthritis type that damages the surface of articular cartilage until the underlying bone. In the past decade, the scientific community has made a considerable effort to improve or discover therapeutical products used as a form of conservative treatment capable of restoring the damaged articular tissue, avoiding, as far as possible, the use of surgical practices. The most common and direct nonoperative application available for OA treatment is the viscosupplementation (VS) procedure that demonstrates a safe, effective method and is less painful for the patients. The most recent works dealing with the design, development, and validation of viscosupplement products in preclinical and clinical trials for OA treatment are overviewed herein. In general, despite the development of new products, hyaluronic acid continues to be among the most reported intra‐articular viscosupplement products used in clinical trials, typically used as an isolated product or conjugated with other biologicals or drugs, such as platelet‐rich plasma and corticosteroids (CS). However, this issue is still demanding innovation. Approaches comprising new biomaterials as VS products, with intrinsic bioactivity, economical, and environmental friendliness, are required.

Using Nonlinear Vibroartrographic Parameters for Age-Related Changes Assessment in Knee Arthrokinematics

Changes in articular surfaces can be associated with the aging process and as such may lead to quantitative and qualitative impairment of joint motion. This study is aiming to evaluate the age-related quality of the knee joint arthrokinematic motion using nonlinear parameters of the vibroarthrographic (VAG) signal. To analyse the age-related quality of the patellofemoral joint (PFJ), motion vibroarthrography was used. The data that were subject to analysis represent 220 participants divided into five age groups. The VAG signals were acquired during flexion/extension knee motion and described with the following nonlinear parameters: recurrence rate (RR) and multi-scale entropy (MSE). RR and MSE decrease almost in a linear way with age (main effects of group p<0.001; means (SD): RR=0.101(0.057)−0.020(0.017); and MSE=20.9(8.56)−13.6(6.24)). The RR post-hoc analysis showed that there were statistically significant differences (p<0.01) in all comparisons with the exception of the 5th−6th life decade. For MSE, statistically significant differences (p<0.01) occurred for: 3rd−7th, 4th−7th, 5th−7th and 6th life decades. Our results imply that degenerative age-related changes are associated with lower repeatability, greater heterogeneity in state space dynamics, and greater regularity in the time domain of VAG signal. In comparison with linear VAG measures, our results provide additional information about the nature of changes of the vibration dynamics of PFJ motion with age.

Vibroarthrographic analysis of patellofemoral joint arthrokinematics during squats with increasing external loads

Background

The patellofemoral joint (PFJ) provides extremely low kinetic friction, which results in optimal arthrokinematic motion quality. Previous research showed that these friction-reducing properties may be diminished due to the increase in articular contact forces. However, this phenomenon has not been analyzed in vivo during functional daily-living activities. The aim of this study was the vibroarthrographic assessment of changes in PFJ arthrokinematics during squats with variated loads.

Methods

114 knees from 57 asymptomatic subjects (23 females and 34 males) whose ages ranged from 19 to 26 years were enrolled in this study. Participants were asked to perform 3 trials: 4 repetitions of bodyweight squats (L0), 4 repetitions of 10 kg barbell back loaded squats (L10), 4 repetitions of 20 kg barbell back loaded squats (L20). During the unloaded and loaded (L10, L20) squats, vibroarthrographic signals were collected using an accelerometer placed on the patella and were described by the following parameters: variation of mean square (VMS), mean range (R4), and power spectral density for frequency of 50–250 Hz (P1) and 250–450 Hz (P2).

Results

Obtained results showed that the lowest values were noted in the unloaded condition and that the increased applied loads had a significant concomitant increase in all the aforementioned parameters bilaterally (p < 0.05).

Conclusion

This phenomenon indicates that the application of increasing knee loads during squats corresponds to higher intensity of vibroacoustic emission, which might be related to higher contact stress and kinetic friction as well as diminished arthrokinematic motion quality.