Varus malalignment is abnormal bowing of the knee, to the outer side.
Page updated April 2024 by Dr Sheila Strover (Clinical Editor)
Standing long-leg X-rays allow the weightbearing mechanical axis to be drawn from hip to ankle, and reveals that there is a varus deformity in the one knee. That is, the axis passes normally through the middle of the joint in one knee, but is medial to the joint in the abnormal knee (red arrow).
Although varus malalignment is a static phenomenon, it may also be associated with dynamic varus thrust which tends to lead to a worsening of any associated osteoarthritis.
What can cause varus malalignment?
Varus malalignment of the knee may be caused by -
- a deformed tibia
- combined deformity of tibia and femur
- ligament imbalance
- constitutional bow-leggedness
- injury
- tumours
- other problems, such as rickets
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Quote from peer-reviewed paper:
"Varus malalignment represents a notorious cause of knee osteoarthritis in adults....[because of] increased loading of the medial tibiofemoral compartment that can lead to faster degeneration of the cartilage of medial compartment."
Citation: Suardi C, Stimolo D, Zanna L, Carulli C, Fabrizio M, Civinini R, Innocenti M. Varus morphology and its surgical implication in osteoarthritic knee and total knee arthroplasty. J Orthop Surg Res. 2022 Jun 3;17(1):299. doi: 10.1186/s13018-022-03184-4. PMID: 35659012; PMCID: PMC9166439.
How does varus malalignment differ from varus thrust?
With varus thrust one notices that the limb 'bows' as weight is taken upon it, but returns to a less bowed or normal position as the weight is shifted to the other side. That is, it is a dynamic phenomenon.
This is different from 'varus malalignment' where the bowing is present even when weight is off that side. That is, it is a static phenomenon.
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Quote from peer-reviewed paper:
"....varus thrust visualized during gait is associated with knee OA progression and should be a target of intervention development...."
Citation: Sharma L, Chang AH, Jackson RD, Nevitt M, Moisio KC, Hochberg M, Eaton C, Kwoh CK, Almagor O, Cauley J, Chmiel JS. Varus Thrust and Incident and Progressive Knee Osteoarthritis. Arthritis Rheumatol. 2017 Nov;69(11):2136-2143. doi: 10.1002/art.40224. PMID: 28772066; PMCID: PMC5659924.
Can varus malalignment be corrected?
An osteotomy is the classic surgical technique for correcting varus malalignment.
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