Abstract
Objectives: Well fixed, ingrown stems in patients with infected, uncemented knee tumor prostheses are difficult to remove. We have shown that it?s not necessary to remove them for infection control. We describe a technique for intraoperative fabrication of antibiotic-impregnated temporary cement prostheses using rush pin endoskeleton during first stage revision of infected, uncemented knee tumor prostheses.
Methods: We used this method in 7 patients with infected uncemented tumor prostheses around the knee. Two patients are awaiting second stage procedures. Surgery involved removing exchangeable components and retaining well-ingrown stemmed intramedullary components. Spacers were made of Rush pins that were bent and placed through hinge of retained component to allow knee movement. Antibiotic impregnated cement was placed around pins.
Results: This method allowed partial weight-bearing, knee movement, stability and pain control between first and second stages. In 4/5 patients infection was eradicated. Second-stage reimplantations were accomplished successfully in 3/5 patients with no obvious metal wear. Mean interval between the 2 stages was 12 weeks. One patient had residual infection requiring amputation and one patient did not agree to further surgery. Overall functional outcome following revision was TESS 82.3/100, MSTS93 73.3/100, MSTS87 23.3/35.
Conclusions: The technique allows maintenance of length, stability and knee joint movement, thus subsequent revision becomes technically simpler. Cement construct has large surface area to maximize antibiotic elution. This method has advantages of low cost, availability of numerous pin dimensions, which allows a custom component. Although there is no obvious wear, this remains a potential concern at articulation of rush rods and retained component.
Correspondence should be addressed to BOOS c/o British Orthopaedic Association, 35-43 Lincoln’s Inn Fields, London WC2A 3PE, England
