Grip on knee Osteoarthritis; DIstraction Versus Arthroplasty (GODIVA) for young knee osteoarthritis patients in regular care.

For relatively young (<= 65 year) patients with severe knee osteoarthritis (OA)
with persistent pain, insufficiently responding to conservative therapy and
joint preserving surgery (*end-stage knee OA*) a knee prosthesis (KP) is
currently the most commonly used treatment. When a first prosthesis is placed
at a young age, patients often need revision surgery later in life. Revision
surgery is complex, costly, and accompanied by multiple complications. The
increasing life expectancy, focus on patient empowerment, and the wish to stay
active and independent up to high age, will probably further increase the
number of revision surgeries. As such, preventing revisions surgery is key.
When a first prosthesis is placed after the age of 65, data show that the need
for revision surgery becomes significantly lower.
Knee joint distraction (KJD) is a joint preserving treatment that significantly
postpones the need for a primary knee prosthesis (up to ~ 10 years in 50% of
cases). KJD is proven to be effective in reducing pain and stiffness and
improving function, although effects seem slightly less compared to a knee
prosthesis. As assessed by *Zorg Instituut Nederland*, KJD is promising but the
current evidence still too limited and thus not yet suitable for reimbursement.
Even in case KJD is less effective, if this is clinically acceptable
(non-inferior), the reduced chance for burdensome revision surgery might still
make it a treatment of choice.

To determine whether KJD is non-inferior on patient reported effectiveness as
compared to a KP (i.e. usual care) for relatively young patients with end-stage
knee OA.
For the substudy: the primary objective is to predict the benefit from knee
distraction treatment by peri-articular bone characteristics.

Pragmatic, open, randomized, multi-centre, non-inferiority trial with 24 months
follow-up.
For the substudy: observational study as add-on study

KP is indicated and surgically implanted according to regular clinical practice
(can be a total- or unicompartmental KP, in line with local practice in
consultation with the patient and conform local national guideline by Dutch
orthopaedic society (NOV)). KJD treatment is performed according to the current
approved concept NOV recommendations for practice.

The benefit of a KP over KJD might be the swifter and slightly better clinical
effect of treatment although at the expense of the original joint and with the
higher risk of revision surgery later in life. The benefit of the KJD over a KP
is that the original joint is preserved with the chance of postponing placement
of a KP and prevention of revision surgery later in life, although with the
burden of a 6-week distraction period with the chance of skin pin-tract
infections, and possibly a slightly (non-clinically relevant) lesser clinical
benefit.
In both arms, at 7 moments questionnaires have to be filled out and at
baseline, and in case of KJD treatment at 24 months a clinic visit takes place
in addition to the typically 4 clinic visits performed in regular practice. In
both arms a comparable number of knee radiographs is made in regular care and
for KJD 1 study specific x-ray will be made at 2 years post-treatment.
In both arms the chance of failure is <5% in the first year after treatment
because of multiple reasons, mostly persisting pain, leading to either revision
surgery in case of a KP or placement of a first KP in case of KJD.
Additionally, there is a chance of infection in both arms. In case of KJD these
are primarily superficial skin pin tract infections, in generally successfully
treatable with oral antibiotics. In both arms a small chance for deeper
infections up to osteomyelitis are seen, needing i.v. antibiotics and/or
nettoyage or even removal of the frame in case of KJD or early revision surgery
in case of KP. Rehabilitation after the intervention(period) is similar for
both treatment arms.

For the substudy: the burden will be a knee-MRI, knee-CT, and DEXA scan at
pre-treatment and 2 years post-treatment, which will take two times an 60-120
min extra out-patient visit time. These image techniques are considered
minimally invasive with CT and DEXA with radiation exposure. Additionally, a
vena puncture for 2* 7 cc blood samples (serum and plasma) at both timepoints
provides a minimal risk. The urine samples are considered riskless.