A varus thrust is when the knee joint thrusts to the outer aspect with each step, as weight is taken on that leg.

Knee thrusts to the outer side with each step.

Joint line gap closed on medial side following medial meniscectomy.
Implications of varus thrust
A varus thrust is the result of a meniscectomy on the medial side, closing the X-ray gap that normally exists because of the radiolucent meniscus that normally fills the gap. Eventually the ligaments can stretch and bow-leggedness becomes permanent rather than only occuring on weight-bearing.
CLINICAL PUBLICATIONS
Frequency of Varus and Valgus Thrust and Factors Associated with Thrust Presence in Persons With or at Higher Risk for Knee Osteoarthritis Chang A et al. Arthritis Rheum. 2010 May; 62(5): 1403–1411.
Varus thrust during walking and the risk of incident and worsening medial tibiofemoral MRI lesions: the Multicenter Osteoarthritis Study. Wink AE, Gross KD, Brown CA, Guermazi A, Roemer F, Niu J, Torner J, Lewis CE, Nevitt MC, Tolstykh I, Sharma L and Felson DT. Osteoarthritis Cartilage. 2017 Jun; 25(6): 839–845.