There are a variety of different factors having significant effects on the range of movement (ROM) after TKR. One can distinguish between patient- and surgery-related factors. The most important patient-related factors are preoperative ROM, algodystrophy, multiple previous operations, trauma history, excessive postoperative pain preventing rehabilitation, anxiety, depression and poor patient self-efficacy [1–4, 6–13]. The most important surgery-related factors are oversized femoral, tibial or patellar TKR components, malposition, infection, improper gap balancing, posterior cruciak ligament (PCL) tightness, instability, anteriorly sloped tibial cuts, prosthesis design and joint line alteration [1–4, 6–13].

When a surgery-related factor is identified as cause of the patient’s stiffness, it clearly increases the chance of success at revision surgery. In patients in which the cause of the stiffness is not clear, at least the exact type of stiffness (e.g. extension deficit, flexion deficit or patellofemoral tightness) needs to be identified [3]. Patellofemoral problems such as patella baja, overstuffing, unresurfaced patella, increased patellar tilt and malrotation of femoral TKR component are the cause of patient’s stiffness in half of the cases [3].