There was no correlation found between changes in synovitis and the reduction in knee pain following brace wearing in patients with Patello-femoral Joint Osteoarthritis (PFJOA).

Patello-femoral Joint Osteoarthritis (PFJOA) refers to a condition that leads to knee pain in middle aged adults. A recent randomized controlled trial had showed that flexible sleeve knee brace in patients with symptomatic PFJOA had significant improvement in pain after 6 weeks and a reduction in bone marrow lesion (BML) volume in the PFJ. The two structures that are found to be casually linked to knee pain are bone and synovitis, innervated by nociceptive fibers. The most common cause of pain is bone marrow lesions. While hyaline cartilage pathology is the signature feature of osteoarthritis, this cartilage is not innervated, and it is not clear whether it is a source of pain. In this trial, there was no significant correlation found between change in pain and change in the BML volume, suggesting that there would be some other underlying mechanisms in pain reduction. A declined synovial tissue volume linked with pain was observed in observational studies, but in this trial, there was no decrease in synovial volume assessed using static contrast enhanced magnetic resonance imaging (CE-MRI). It was explained that there occurs a less sensitivity for pain in static measures of synovial volume than measures of synovial perfusion, assessed using DCE-MRI. DCE-MRI is a technique that uses repeated imaging sequences of the joint while injecting contrast agent systemically. This technique helps calculate the enhancement rates of tissues, perfused by contrast agent. The tissue enhancement rates are directly linked with joint inflammation in rheumatoid arthritis (RA) as compared to changes to static tissue volume measures that correlates with change in pain following intra-articular steroid therapy. The present study explains that treatment with intra-articular injection causes a major reduction in perfusion of the synovium and this reduction is closely linked with pain reduction than measures of static synovial volume.

Rationale behind the research:

The braces therapy can be used to diminish contact stress across the joints causing less microscopic damage and less need for the synovium to clear debris. It was hypothesized that pain reduction after brace use can be due to the changes in synovitis and this research was conducted to clarify the above hypothesis.

Objective:

To study the changes in synovitis assessed using dynamic imaging and their correlation with reduction in pain.

Study outcome measures

• The baseline characteristics included assessment of DCE-MRI variables using MRI
• Primary endpoints: Assessment of pain on a VAS of pain on nominated aggravating activity (VASNA) (0 mm = no pain, 100 mm = worst pain) and change in enhancement rates of synovium
• Secondary endpoints: Assessment of changes in pain using Knee Osteoarthritis Outcome Score (KOOS) pain scale

Time Points: Baseline and 6-weeks

Study outcomes

• Baseline: There were no significant differences observed at baseline.
• Primary outcomes: There was a clear pain improvement in the brace users compared to controls (VASNA − 16.87 mm, p= <0.001) {Fig.1}

VASNA: visual analogue scale of pain on nominated aggravating activity; KOOS: knee osteoarthritis outcome score

Figure 1. Assessment of pain on a VAS of pain on nominated aggravating activity and change in enhancement rates of synovium

• Secondary outcomes: There was no significant change to the dynamic synovitis parameters among brace users nor was pain change correlated with change in dynamic synovitis parameters.
  

The results of this study indicated that changes in synovitis, assessed using a sensitive imaging technique were not associated with improvement in pain. There was a small reduction in RER (p=0.04) and Ktrans (p = 0.05) variables within control group but these results were not clinically significant. In this study, the DCE technique was used which is a more sensitive method of detecting synovitis than static contrast enhanced imaging. The assessment of synovitis using DCE-MRI was linked with pain reduction followed by steroid injection than static MRI imaging.