The purpose of this study was to review types, pro- duction mechanisms, treatment and results of ours intraope- rative fractures during primary total knee arthroplasty. We had 18 fractures in 2520 primary knee arthroplasties, 16 with varus deformities and valgus in another 2. One patient had corticoids, 15 had overweight and 2 morbid obesity. All implants were posterior stabilised. Type of fracture: 4 were of the medial femoral condyle and 2 lateral; the medial tibial condyle in 8 and on the anterior cortex medial to tibial tubero- sity in 4. Mechanism of injury in the femur was while impac- ting the components or when the trial reduction was perfor- med; in the tibia during the making of the keel house or meanwhile impacting the implants. Treatment: Cement, Kirschner wire or screws. Partial weight bearing was advised for 6-8 weeks. All fractures united. At the last follow-up of two or more years no complaints were found.