**2. Classification**

The SKN can be presented clinically in loss of extension (LOE), loss of flexion (LOF), mixed or ankylosed. The major troubles in LOE are adhesions in suprapatellar pouch and in medial and lateral gutters, contracture of extensor mechanism, patellofemoral joint fusion, and loss of tibiofemoral joint space. The SKN in LOF, the extensor mechanism that is elongated with posterior capsule, posterior cruciate ligament (PCL), and collaterals ligaments are contractured. The posterior osteophytes causes a mechanical barrier to achieve complete ROM. Ankylosed knee can be associated with knee arthrodesis, infection, reconstruction after tumor ressection, after severe trauma with distal femur, and tibial plateau fractures. The classification proposed by Sharma [13] is based on the degree of loss of ROM in the knee joint, as shown in **Table 1**.


### **Table 1.**

*Classification for stiff/ankylosed knees proposed by Sharmal [13].*

This classification provides a guidance for surgeons related to surgical approach, type of prosthetic implants, and helps to presume functional outcome after TKA.
