This prospective, randomized, single-blinded clinical trial compared a mobile-bearing total knee system with two types of fixed-bearing total knee systems in patients undergoing cemented total knee arthroplasty. The devices to be used are FDA approved: the Sigma Knee System (mobile-bearing), the Sigma, Pressfit Condylar posterior cruciate substituting (fixed-bearing) system with a metal backed tibial tray, and the Sigma press-fit condylar posterior cruciate substituting system (fixed bearing) with an all polyethylene tibial tray.
The surgical procedures were performed by 4 experienced orthopedic surgeons with a subspecialty interest in total knee arthroplasty. A midline skin incision and medial parapatellar arthrotomy were used to expose the knee. The distal femoral resection was performed with an intramedullary alignment guide, and the proximal tibial resection was performed with an extramedullary alignment guide. Knees with fixed deformities had a surgical release of the contracted tissues on the medial or lateral side, as appropriate, to obtain symmetric balance of the total knee replacement in both flexion and extension. The flexion and extension gaps and the medial and lateral soft-tissue structures were balanced in accordance with standard techniques.
Patients began progressive weight-bearing on the first postoperative day, and active knee range of motion was initiated with 24 hours after surgery. Patients were typically discharged on the fourth or fifth postoperative day after obtaining the ability to walk with a walker, to ascend several stairs, and to flex the knee 290 degrees. Patients were asked to return for examination and radiographs at 3 months, 1 year, 2 years, and 5 years after surgery.
Inclusion Criteria:
- Patients undergoing unilateral primary knee surgery for degenerative joint disease (DJD).
Exclusion Criteria:
- Severe deformity greater than or equal to 20 degrees varus, valgus malalignment
- Osteomyelitis, septicemia, or other active infections that may spread to other areas of the body
- The presence of infections, highly communicable diseases, e.g., AIDS, active tuberculosis, venereal disease, hepatitis
- Significant neurological or musculoskeletal disorders or disease that may adversely affect normal gait or weight bearing
- Metastatic disease
- Any congenital, developmental, or other bone disease or previous knee surgery that may, in the surgeon's judgement, interfere with total knee prosthesis survival or success, e.g., Paget's disease, Charcot's disease secondary to diabetes, severe osteoporosis, previous high tibial osteotomy, etc.
- Presence of previous prosthetic knee replacement device (any type)
- Arthrodesis of the affected knee
- Patients not requiring patella resurfacing.
Participants may be in this research study for up to five years.
What is involved in this research study?
You will undergo a total knee replacement and will be randomized (as in the flip of a coin) to receive one of three FDA-approved knee replacement systems. One knee system has plastic that locks into a metal tray that is firmly fixed in the leg. One knee system uses a metal "runner" that rubs against plastic that is firmly fixed in the leg. The other knee system uses a metal "runner" that rubs against plastic that is able to rotate freely. All knee systems have a track record of clinical success.
All the components will be fixed to the bone with bone cement. You will come to the hospital on the day of your surgery and remain for four to six days. Just prior to the surgery, you will be randomly assigned to receive one of the three knee designs (you will have approximately a 30% chance of receiving any design). All groups will be given the same after-surgery treatment. You will be given therapy and assisted in walking and bearing as much weight as you can the day after surgery. X-rays, a physical examination of the knee, and a simple survey will be done before surgery and again at two months, one year, two years and five years after surgery. This follow-up is typical of our total knee patients and may be done at Mayo or locally.
Last updated: 12/10/2012
NCT ID: NCT00589108
IRB Number:271-01
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