Abstract
We performed 112 primary total knee replacements in patients under the age of 50, using a unique implant designed to pivot laterally during range of motion.
This design more closely approximates the motion of an ACL deficient knee and controls for the anterior translation typical of more traditional designs. Patients were followed prospectively for a minimum of 3 years (range, 36 to 54 months) All patients were rated both clinically and radiographically using Knee Society Scores, SF-36 and standard radiographic instruments. Patients also completed a validated questionnaire that examined activity level, functional outcomes and ability to return to sports. Patients were compared to case matched historical controls that received a traditional, medially pivoting or flat on flat knee design.
The senior author performed all procedures using a minimally invasive technique with preservation of the quad tendon and accomplished without lateral release. Inclusion criteria were patients under 50 with documented, tricompartmental osteoarthritis. All patients received the same posterior cruciate retaining, laterally pivoting knee prosthesis. Implanted with cement. All patients had resurfacing of the patella performed. The patients were compared to a case matched group of patients that received a modern medially pivoting knee replacement design.
At last follow up, the mean Knee Society functional score was 94. There were no infections, fractures or other major complications in this group. Patients reported quicker recovery of quadriceps function, return to walking without assistance and quicker return to vigorous sports such as tennis. Functional outcomes were statistically improved over historical controls. There was no loss of radiographic alignment or increased signs of loosening compared with historical standards on the most recent radiographs.
Total knee arthroplasty using a ACL substituting device was functionally superior to medially pivoting devices in this patient population. Patients reported better quadriceps dependent activities such as stair climbing and getting up from a chair. They were able to participate in more active sports without late signs of loosening or osteolysis. The authors can recommend this design in younger patients interested in vigorous activity, but full evaluation of this prosthesis will require longer-term results.
Correspondence should be addressed to Diane Przepiorski at ISTA, PO Box 6564, Auburn, CA 95604, USA. Phone: +1 916-454-9884; Fax: +1 916-454-9882; E-mail: ista@pacbell.net
