An alternative version of the Sheehan knee arthroplasty is presented allowing additional replacement of the patellofemoral joint as there is a definite need for replacement of this part of the knee joint in osteoarthritis. However, the original Sheehan design which is considered to be one of the best compromises amongst semiconstrained knee prostheses does not offer this possibility. The design of the modification follows the design criteria of the original Sheehan knee and attempts to restore the necessities of normal patella function. Loading tests on the modified prosthesis were carried out prior to clinical trials. Surgical technique and additional aligning instruments are described. The clinical series comprises 16 cases up to now and no complications occurred so far. The indication is strictly limited to advanced osteoarthritis of the knee.