Abstract
Purpose: Conducting a prospective study comparing the short-term results of minimally invasive total knee replacement surgery using a conventional prosthesis (i.e. not specifically designed for minimally invasive surgery – MIS, AGC Biomet) with knee arthroplasties performed via a transvastus approach.
Operative Technique: MIS knee arthroplasty is performed via a medial parapatellar skin incision from the supero-medial pole of the patella to the tibial tuberosity. The major difference is the lack of quadriceps muscle dissection and the lack of patellar inversion. The instruments fit into the incision, though some of the pins have to be inserted percutaneously. In order to reduce patello-femoral pressure and pain, an osteophytectomy is performed followed by sawing a slice of the patella and denervation using a diathermy. The wound is closed with intra-dermal sutures and a drain is not used.
Materials and Methods: Forty-five consecutive knee replacements were randomized into either a conventional trans-vastus approach (22 patients) or a minimally invasive procedure (23 patients). The patients were assessed using an HSS knee score, a VAS score and knee range of motion every day during hospitalization was recorded separately. Blood consumption and length of hospitalization were recorded as well. The patients were followed for a minimum of 3 months. Radiographic evaluation included prosthesis alignment in the AP and lateral views.
Results: Pre-op age, sex, VAS score and HSS were similar in both groups. Initial limb alignment averaged 9 degrees of varus in both groups. Pre-op range of motion was similar in both groups -5 degrees of extension and 90 degrees of flexion. Operative time was similar in both groups. Length of hospital stay was similar in both groups. Blood usage was diminished in the MIS group by an average of 0.8 units.
At the 2-weeeks and 6-weeks time-point the range of motion in the MIS group was better both in flexion and in extension by an average of 20 degrees, than in the conventional surgery group. This difference was nullified at the 3 months time-point. Radiographic alignment was similar in both groups. The limb alignment post-op averaged 3 degrees of varus.
Conclusions: MIS knee arthroplasty appears to yield similar results to conventional arthroplasty regarding prosthesis alignment and hospitalization.
The abstracts were prepared by Ms Orah Naor. Correspondence should be addressed to Israel Orthopaedic Association at PO Box 7845, Haifa 31074, Israel.
