thesis
Unicompartmental Osteoarthritis of the Knee: Diagnosis and Treatment of Malalignment
- Publication date
- 17 May 2006
- Publisher
- Osteoarthritis (OA) of the knee is a common medical condition that is often seen in
general practice and causes considerable pain and immobility. In the United States,
approximately 6% of the population aged 30 years and older and 12% of the population
aged 65 years and older suffer from knee osteoarthritis.1 In addition to the consequences
for the patient, osteoarthritis forms a considerable burden for society because of its
chronic course and the high costs of interventions.2 In the Netherlands 1% of the total
medical costs is spent on osteoarthritis.3
Osteoarthritis of the entire knee is distinguished from osteoarthritis of one compartment,
which is generally caused by a mechanical problem.4 The mechanical axis of a straight
leg is defined as a line passing from the centre of the hip, through the centre of the knee
to the centre of the ankle.5 Patients with osteoarthritis of the medial compartment often
have varus alignment, and the mechanical axis and load bearing pass through the medial
compartment (=genu varum arthroticum). Patients with osteoarthritis of the lateral
compartment often have a valgus alignment, and the mechanical axis and load bearing
pass through the lateral compartment (genu valgum arthroticum). Axial malalignment
(varus or valgus alignment) increases the risk for progression of knee osteoarthritis and
predicts a decline in physical function.6
Besides the usual treatment for osteoarthritis, specific interventions for unicompartmental
knee osteoarthritis include conservative interventions e.g. (knee braces and foot/
ankle orthoses) as well as surgical treatments (e.g. a correction osteotomy to reduce load
of the osteoarthritic compartment of the knee).7-15
The anterior-posterior whole leg radiograph (WLR) is considered the gold standard for
determining axial alignment and serves as the basis for planning a knee osteotomy in
patients with osteoarthritis. In many studies the WLR has been made in standing position,
whereas others have preferred the supine position.13,14,16,17