[The medial closed-wedge osteotomy of the distal femur for the treatment of unicompartmental lateral osteoarthritis of the knee]

Abstract

Objective: Shifting of the mechanical axis from the lateral to the medial compartment in patients with lateral osteoarthritis in combination with valgus deformity.

Indications: Osteoarthritis of the lateral compartment in combination with valgus deformity of the (distal) femur. Posttraumatic and congenital valgus deformities of the (distal) femur.

Contraindications: Osteoarthritis of the medial compartment (>or=grade 3 on Outerbridge Scale). Total loss of the medial meniscus. Acute or chronic infections. Rheumatoid arthritis. Heavy smoking. Extension or flexion deficit>20 degrees. Poor soft-tissue conditions on site of surgery.

Surgical technique: Optional: arthroscopy before osteotomy. Anteromedial skin incision, subvastus approach with blunt preparation around the vastus medialis muscle and separation of this muscle from the intermuscular septum. The posterior osteotomy is marked with Kirschner wires (OGD [osteotomy guiding device], Synthes, Switzerland, can be used optionally). The biplanar cut is marked on the bone with an electrocautery device. The bone cuts start with the posterior incomplete osteotomy, followed by the anterior biplanar cut. After finishing the osteotomy (three bone cuts!), the bone wedge can be removed. Closing the osteotomy should start very gently as a plastic deformation of the bone. A radiologic control of the leg alignment and the mechanical axis is achieved with an alignment rod (Synthes, Switzerland). The plate should be inserted under the vastus medialis muscle. It is very important, that the surgeon controls the correct anteromedial position of the plate at the distal femur (right and left version of the implant). Fixation of the plate with locking screws distally. Positioning of a lag screw in the dynamic hole directly above the osteotomy. Insertion of monocortical screws in the three remaining holes proximal of the lag screw. Finally, the lag screw is changed to a self-tapping bicortical locking head screw. X-ray control, wound closure.

Postoperative management: Elastic bandage of the leg up to the thigh in the operating room. Change of the dressing on day 1 after surgery. Ice treatment. Walking on crutches starting day 1 after surgery. Physiotherapy and manual lymph drainage starting on day 1 after surgery. Partial weight bearing for the first 4-6 weeks after surgery. Suture removal after 10-12 days. X-ray control on day 3 and 6 weeks after surgery. Discharge possible, if wounds are dry (day 4-7).

Results: Between January 2005 and October 2008, 60 patients were treated with medial closed-wedge osteotomy of the distal femur (since 11/2006 only with biplanar osteotomy technique) at the Department of Trauma and Reconstructive Surgery, Diakoniekrankenhaus Henriettenstiftung Hannover, Germany. The average wedge size was 7.6 mm (4-13 mm). The mean age was 39.7 years (17-79 years). The patients had had 2.3 previous surgeries. The mean follow- up was 21 months (3-45 months). Freiling D, et al. Biplanare Osteotomie bei unikompartimentaler lateraler Kniegelenkarthrose Flexion was 126 degrees (95-140 degrees) preoperatively, and 128 degrees (105-140 degrees) postoperatively. 25 patients had at least 5 degrees extension deficit (5-15 degrees) before surgery, whereas ten patient did not reach the full extension at follow-up examination. The Tegner Activity Score increased from 2.8 (1-4) preoperatively to 5.6 (2-9) postoperatively, in IKDC (International Knee Documentation Committee) Score, 18 patients reached grade A, 27 grade B, nine grade C, and six grade D. The visual analog scale (VAS) score decreased from 6.8 (8-2) preoperatively to 3.1 (0-7) postoperatively. Seven patients had revision surgery (three times delayed union/nonunion of the osteotomy, one superficial and one deep infection, one hematoma, one fracture [proximal of the internal plate fixator] after a fall).