Transient Osteoporosis of Pregnancy (TOP) is an uncommon condition that affects women primarily in the final trimester of pregnancy. The condition typically affects the hip presenting with severe, non-traumatic joint pain that limits mobility and leaves the patient susceptible to fracture. The etiology of TOP is not clear. While generally a self-limiting condition, recognition and management, including advice regarding restriction of weight bearing, is important to reduce the risk of fracture. This report describes an atypical presentation of TOP with unilateral knee involvement.