Can changes in joint fluid explain cartilage repair after joint distraction?

Knee joint distraction (KJD) in treatment of severe knee osteoarthritis (OA)
has shown significant prolonged (at least 5 years) clinical benefit (decreased
pain and increased function) in about 80% of patients. Importantly, KJD results
in cartilage tissue repair (increase in thickness and volume observed by X-ray,
MRI, and serum/urine biochemical marker analyses. This cartilage tissue repair
is considered to underlay the prolonged clinical benefit after this relatively
short treatment. Cartilage tissue repair, being the goal of many research
groups, is considered unique as cartilage tissue repair has for a long time
been considered very difficult if not impossible. It is anticipated that this
unique tissue repair activity is caused by an altered joint homeostasis
(mechanically and biochemically) as a result of distraction.
At present knee joint distraction becomes implemented in clinical practice. In
4 institutes in the Netherlands (and some institutes abroad) it is performed
now in regular clinical practice. However, there is no knowledge on the
mechanisms underlying the cartilage tissue repair upon this treatment. Such
knowledge is of significant importance as it will provide tools for
(improvement of) cartilage tissue repair strategies in osteoarthritis. The
obtained knowledge might be of help for many attempts focusing at cartilage
tissue repair studied by the many groups worldwide.

To study the change in joint homeostasis induced by knee joint distraction.

Pilot, observational study, with invasive (joint fluid sampling) measurements.

Benefit: Patients will be treated in regular practice with knee joint
distraction. Patients have no direct benefit of participating in the study.
Results will elucidate the underlying mechanisms by which cartilage tissue
repair can be supported (as observed during joint distraction) and may provide
tools for improvement of (novel) cartilage repair strategies. Joint distraction
is unique in this respect because there are no other treatments that result in
cartilage tissue repair, and as such the only way to unravel such mechanisms
(from insight-out).

Burden: At baseline (under anaesthesia during placing of the distraction
device), half way (3±1 weeks post distraction, under local anaesthesia), and at
the end (week 6; under anaesthesia when the frame is removed), 2 cc joint fluid
(less than 10% of the joint fluid present) will be obtained by needle
aspiration using a syringe. The 1st and 3rd needle aspiration will be under
anaesthesia (as performed in regular clinical practice) without discomfort. The
2nd needle aspiration (under local skin anaesthesia with Lidocaine will provide
some discomfort. However, in general the knee joint is characterised by (a
slight) effusion during distraction and an extra joint space of ~5 mm because
of distraction is present, which will significantly facilitate aspiration.

Risks: a) A potential, (although considered very small) chance on a diminished
clinical benefit because of interference in the joint homeostasis during joint
distraction. b) A potential, (although considered small) chance on an
intra-articular infection because of the three intra-articular needle
punctures. However, 2 of these 3 are taken under full surgical conditions
(operating rooms). The remaining one is a general procedure in orthopaedics and
rheumatology practice performed at the out-patients clinics, although for this
study performed when a distraction frame is present. As such, optimal infection
prevention is needed and good monitoring will be performed. In case
intra-articular infection would occur, regular clinical care is indicated.