Abstract
Introduction
The legacy constrained condylar knee prosthesis (LCCK, Zimmer.) is designed for primary and revision total joint arthroplasties that need additional stability due to ligament deficiency and to compensate for bone defects. In this follow-up we present our mid term results.
Methods and Material
Between November 1999 and January 2006 59 patients were provided with 67 LCCK knee endoprotheses. 38 prostheses were implanted in cases of revision surgery and 29 as primary implants. The mean patient age was 76 years (range 22–93). Indications for revisions were 20 aseptic loosenings, 11 late infections, 7 instabilities (5 cases due to polyethylene wear). Indications for primary arthroplasties were 16 severe valgus and 7 severe varus deformities, 5 cases of osteoarthritis after infection and 1 posttraumatic deformity. 36 femur components (54%) and 34 tibia components (51%) were augmented. 31 stems were fixed cementless, 15 stems were cemented (6 with an intermedullary plug). We evaluated the results prospectively with a clinical inspection and x-ray. Clinical rating systems used were the Knee society, SF-36 Quality of life and Womac score. The mean follow up was 5.6 years. 42 patients were examined, 10 questioned on the telephone, 3 deceased, 12 had to be revised and 2 were lost for follow-up.
Results
We had an increase in ROM from 93° to 110°. The Knee Society score improved from 40 to 75 and the function score improved from 46 to 72. The early complications included 1 peroneal lesion, 1 intraoperative fracture, 7 limitations in movement, 10 wound healing problems and 1 thrombosis. 12 revisions had to be performed. 1 septic loosening, 1 synovectomy, 4 aseptic loosenings, 3 secondary patella replacements, 1 traumatic rupture of the quadriceps muscle, 1 chondrosacroma and 1 revision performed in another clinic. 25 (80%) uncemented stems, 3 (33%) cemented stems and 1 (17%) of the stems cemented with an intramedullary plug showed radiolucencies.
Conclusion
The LCCK prosthesis can be recommended as a primary implant and for revisions in cases of severe instability or severe bone loss. Due to the bad general health of the patients and preoperative situation of the knee joints the results are satisfactory. All revisions due to aseptic loosening had to be performed on LCCKs with uncemented stems.
