Cementless total knee arthroplasty in patients with inflammatory arthritis and compromised bone.

Patients with bone compromised by inflammatory arthritis and medications are often excluded from cementless total knee arthroplasty (TKA) because of concerns regarding implant fixation and ingrowth. However, many such patients are young and at long-term risk for implant failure no matter what the fixation technique. Improved implant designs and technique may improve results. Cementless arthroplasty was performed in 45 patients with inflammatory arthritis. There were 38 patients with 53 implants available for follow-up evaluation during a 2- to 6.4-year period (average, 3.3 years). Medications included steroids (16 patients), nonsteroidal antiinflammatory drugs (36 patients), and cytotoxic agents (12 patients). Twenty-nine patients were using at least two types of medication. Prostheses included the Tricon P, Tricon M, Miller-Galante, and Anatomic Modular Knee (AMK) prosthesis. The procedures were performed using standard ligament-balancing techniques. Tibial resections were within 1 cm of the tibial plateau, thereby necessitating extensive bone grafts in ten patients. Tibial components were chosen for maximal cortical rim contact. Roentgenograms were reviewed for alignment, tibial rim contact, radiolucencies, gaps, sclerosis, and subsidence. Patients with no evidence of gap or lucency had spot films under image control. Hospital for Special Surgery knee scores averaged 47 preoperatively and 88 at follow-up examination. Alignment was from 3 degrees valgus to 9 degrees valgus (average, 6 degrees valgus), with a tibial axis of 0 degrees +/- 2 degrees. Plateau coverage was within 2.4 mm (average) of the cortical rim in all planes in the anteroposterior (AP) and lateral views. Tibial sclerosis occurred with equal frequency in all AP zones and was present equally in anterior and posterolateral zones. Gaps and lucencies were more common laterally. Fifteen femoral components showed a disturbing, localized osteopenia. Sclerosis, gap, and lucency were most common anteriorly. Cementless TKA with appropriate technique can produce results comparable to cemented surgery in patients with bone quality compromised by inflammatory arthritis, steroids, and nonsteroidal and cytotoxic agents. The femoral bone response suggests an intimate bone implant relationship. The tibia shows little direct coupling of prosthesis to bone. These responses are similar to reports from other studies. Fixation is sufficient to allow for continued analysis over time and results are encouraging.