Hyaluronate effects on synovium and synovial fluid. A prospective blinded study in patients with osteoarthritis of the knee

Can Combining Hyaluronic Acid and Physiotherapy in Knee Osteoarthritis Improve the Physicochemical Properties of Synovial Fluid?

Known as the degenerative disease of the knee with the highest prevalence, knee osteoarthritis (KOA) is characterized by a gradual destructive mechanism that, in severe cases, can provoke the need for total knee substitution. As the disease progresses, various enzymatic, immunological, and inflammatory processes abnormally degrade hyaluronic acid (HA), SF's main component, and affect the concentrations of specific proteins, with the final results seriously endangering synovial fluid (SF)'s rheological and tribological features and characteristics. No effective treatments have been found to stop the progression of KOA, but the injection of HA-based viscoelastic gels has been considered (alone or combined with physiotherapy (PT)) as an alternative to symptomatic therapies. In order to evaluate the effect of viscosupplementation and PT on the characteristics of SF, SF aspirated from groups treated for KOA (HA Kombihylan® and groups that received Kombihylan® and complex PT) was analyzed and compared from analytical, spectrophotometrical, and rheological perspectives. In the patients treated with PT, the SF extracted 6 weeks after viscosupplementation had a superior elastic modulus (G') and viscous moduli (G″), as well as a homogeneous distribution of proteins and polysaccharides. The viscosupplementation fluid improved the bioadhesive properties of the SF, and the use of the viscosupplementation fluid in conjunction with PT was found to be favorable for the distribution of macromolecules and phospholipids, contributing to the lubrication process and the treatment of OA-affected joints.

Hyaluronan Injections Show No Histologic Evidence of Adverse Tissue Effects

Background:

The safety of hyaluronan intra-articular injections is mostly based on animal studies and clinical evidence rather than histologic studies from human administration.

Objective:

This study analyzed the histologic effects of viscosupplementation with sodium hyaluronate on the synovium and articular cartilage of human knee specimen status post total knee arthroplasty within 3 years of viscosupplementation.

Methods:

Twenty-four specimens from total knee arthroplasties from April 2012 to August 2016 at NYU Winthrop Hospital were selected for microscopic analysis. All cases had a diagnosis of end-stage osteoarthritis at the time of surgery. Thirteen of the cases had 3 viscosupplementation injections of the knee with Euflexxa, a hyaluronate-based viscosupplementation agent, within 3 years preceding a total knee replacement. The remaining 11 did not receive viscosupplementation and were incorporated as controls. Upon histologic review, synovium was categorized by degree of hyperplasia and inflammation and the presence or absence of foreign material and giant cell reactions. Residual articular cartilage was categorized by staining intensity, and the presence or absence of crystals, foreign material, and giant cell reactions.

Results:

No significant difference was found between these groups for degree of synovial hyperplasia (P = .33) or for cartilage staining density (P = .42). None of the samples displayed evidence of foreign material, crystals, or giant cell reactions.

Conclusion:

In this cohort of patients, we demonstrated that Euflexxa was administered without any discernible microscopic adverse tissue effects.

The importance of synovial inflammation in osteoarthritis: current evidence from imaging assessments and clinical trials

Synovial abnormalities have been observed at multiple stages of osteoarthritis (OA). Increasing evidence suggests that it may play an important role in the OA pathological process. Many assessment systems using magnetic resonance imaging (MRI) and ultrasound have been established to detect synovial inflammation in OA. These have been used to inform the current investigation of OA disease phenotypes and progression and can be utilised in the future for clinical trials developing potential treatments. This narrative review aims to illustrate the importance of synovial tissue in OA and provide an overview of imaging assessments and possible therapies targeting synovial abnormalities.

The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review

BACKGROUND

Knee osteoarthritis (OA) is one of the leading causes of disability within the adult population. Current treatment options for OA of the knee include intra-articular (IA) hyaluronic acid (HA), a molecule found intrinsically within the knee joint that provides viscoelastic properties to the synovial fluid. A variety of mechanisms in which HA is thought to combat knee OA are reported in the current basic literature.

METHODS

We conducted a comprehensive literature search to identify currently available primary non-clinical basic science articles focussing on the mechanism of action of IA-HA treatment. Included articles were assessed and categorized based on the mechanism of action described within them. The key findings and conclusions from each included article were obtained and analyzed in aggregate with studies of the same categorical assignment.

RESULTS

Chondroprotection was the most frequent mechanism reported within the included articles, followed by proteoglycan and glycosaminoglycan synthesis, anti-inflammatory, mechanical, subchondral, and analgesic actions. HA-cluster of differentiation 44 (CD44) receptor binding was the most frequently reported biological cause of the mechanisms presented. High molecular weight HA was seen to be superior to lower molecular weight HA products. HA derived through a biological fermentation process is also described as having favorable safety outcomes over avian-derived HA products.

CONCLUSIONS

The non-clinical basic science literature provides evidence for numerous mechanisms in which HA acts on joint structures and function. These actions provide support for the purported clinical benefit of IA-HA in OA of the knee. Future research should not only focus on the pain relief provided by IA-HA treatment, but the disease modification properties that this treatment modality possesses as well.

Importance of synovitis in osteoarthritis: evidence for the use of glycosaminoglycans against synovial inflammation

OBJECTIVES

After detailing the different aspects of synovial inflammation (i.e., cellular, biochemical, and vascular) and based on the current knowledge, the aim of this review was to collect the available in vitro and in vivo data regarding the potency of some glycosaminoglycan (GAG) compounds to target synovial inflammation, an important aspect of osteoarthritis.

METHODS

The first part of the review corresponds to a qualitative review of the inflammatory status of OA synovial membrane. The second part corresponds to a systematic review of the literature regarding the potential effects of some GAGs on the previously described phenomenon.

RESULTS

The synovial aspect of the inflammatory status of OA has been detailed. Chondroitin sulfate has demonstrated to control the three aspects of synovial membrane inflammation: cell infiltration and activity, biochemical mediators release, and angiogenesis. Glucosamine is also active on both cellular and molecular aspects of the inflammatory reaction. Hyaluronic acid seems to be anti-inflammatory in its native form, while products of degradation are reported to be pro-angiogenic.

CONCLUSION

Much evidence suggests that some of the studied GAG compounds could target different aspects of synovitis. Some of them could be considered in combination therapy since they exhibit complementary properties. Most of the studies have concentrated on articular cartilage and chondrocytes. In order to achieve a structure modification, one may now consider all joint tissues and investigate the drug potency on all of them. Potent treatment should trigger the most important features of OA: cartilage degradation, subchondral bone sclerosis, and all aspects of synovial inflammation.