The effect of coblation treatment on knee cartilage quality in patients with meniscal lesions and cartilage loosening of the knee

Healthy cartilage of the knee joint with smooth articular surfaces is important
for normal physiological knee function. Cartilage defects of the knee are quite
common, affecting about 10% of the population. (Sellards, 2002) Cartilage
lesions are detected in approximately 60% of all knee arthroscopies
(Widuchowski, 2007). Small cartilage lesions are usually not treated
surgically, whereas larger defects or unstable cartilage flaps are treated with
different surgical procedures, ranging from lavage, bone marrow stimulation,
tissue transplantation or mechanical debridement (MD).

Coblation treatment of degenerative cartilage in the knee is a safe alternative
to MD. With coblation treatment, radiofrequency energy is used to break
molecular bonds to dissolve soft tissue at low relative temperatures. Recent
studies have shown that coblation treatment creates a smoother cartilage
surface in human cadavers compared to MD (Gambardella, 2016), and this effect
is maintained up till 6 months in goat model studies. (Smith & Nephew) Human in
vivo studies have shown that coblation treatment results in better patient
reported outcome up till 10 years when compared to mechanical debridement.
(Spahn 2008, 2010, 2016). Second-look arthroscopy at different follow-up
moments showed that 3 out of 25 patients treated with coblation therapy
demonstrated evidence of progression. (Voloshin, 2007). However this was
studied in a small part of a larger cohort and at varying follow-up.

PET/CT is a nuclear imaging technique with the ability to fuse functional and
anatomical imaging. PET/CT using Na18F (Na18F-PET/CT) enables the
identification of increased bone turnover and provides 3D-quantitative data on
osteoblastic activity. Although it is mainly used for oncological indications,
the use for benign bone and joint disorders, including the knee, is a novel
application of Na18F-PET/CT. (Smit 2017; Jonnakuti et al. 2018; Haddock et al.
2019; van der Bruggen et al. 2020) Arthrography, using intra-articularly
injected contrast agent, is an established clinical technique for imaging of
cartilage abnormalities (Omoumi et al. 2009, 2017)(Omoumi et al. 2009 en 2017).
The combination of nuclear imaging and arthrography provides functional
information about increased bone turnover with morphological details of knee.
(Bhure U, Roos JE, Pérez Lago MDS, Steurer I, Grünig H, Hug U 2018) Therefore,
Na18F-PET/CT with arthrography of the knee is a promising tool for non-invasive
assessment of cartilage. (Smit 2017; Bhure U, Roos JE, Pérez Lago MDS, Steurer
I, Grünig H, Hug U 2018; Jonnakuti et al. 2018) The in vivo effects of
coblation treatment on knee cartilage in a larger patient cohort up to one year
post-treatment have not been studied. Na18F-PET/CT with arthrography can be
used to study these effects.

Primary Objective:
To study the in vivo effect of coblation treatment on knee cartilage quality in
patients with meniscal lesions and partial cartilage loosening of the knee.

Secondary Objective:
To study the relationship between knee cartilage quality after coblation
treatment, and patient reported outcome and patient characteristics.

A cohort study, with follow-up up till one year after surgery.

Radiofrequency energy is applied using the Werewolf Coblation system (Smith &
Nephew Inc., Cordova, TN, USA). The WEREWOLF System and FLOW 50 Wand using Lo
mode is FDA-cleared for chondroplasty and articular cartilage debridement. This
low-energy, low-suction setting minimizes damage to surrounding healthy
chondrocytes and is therefore the preferred setting for articular cartilage
removal. A traditional two-portal (anterolateral and anteromedial) arthroscopy
will used to perform the chondroplasty treatment. (Gambardella, KNEE TECHNIQUE
GUIDE)

The benefits for the subjects are that, according to the current literature,
coblation treatment results in better patient reported outcome when up to 10
years when compared to mechanical debridement. The extra time subjects have to
invest in the study is about 4.5 hours over a year, with one extra visit to the
hospital. This may be beneficial for some subjects, with an extra long-term
check-up. There is a low risk of infection, and skin irritation due to leakage
after intravenous injection of the tracer. Otherwise, both coblation treatment
and Na18F-PET/CT are safe procedures and the burden of the PROMS are low.
Average radiation dose for Na18F-PET/CT is 1.96 mSv, resulting in 2 x 1.96 mSv
= 3.92 mSv over the course of a year. This falls in the risk classification 3:
1-10 mSv and is considered safe since this is less than two times the annual
natural background radiation in the Netherlands (2.5 mSv/year).