Introduction Antibiotic-loaded cement spacers are commonly used in the two-stage management of the infected total knee replacement (TKR). Static spacer blocks make exposure and reimplantation difficult because of soft-tissue retraction and muscle shortening. To avoid these problems, a temporary articulating moulded implant has been recently introduced in the marketplace. The device is industrially preformed in three sizes (two articulating components), has standardised mechanical and pharmacological characteristics.
Methods We present a multicentre study designed to assess the safety of the device, patients’ satisfaction and functional outcome at a minimum follow-up of six months. Twenty-four knees have been treated for TKR deep infection due to CNS (15),S.aureus (three),E.coli (one),mixed flora (two), unidentified (three). Continuous passive motion and partial/touch weight-bearing were started after surgery. Second-stage surgery was performed after normalisation of serological parameters, a minimum period of six weeks of antibiotic therapy, and a sterile aspiration of the joint. The spacer was removed and a new prosthesis was inserted in all patients. The mean implantation time of the spacer was 16 weeks (range 8 to 38).
Results Suppression of infection was observed in all patients at a minimum follow-up of six months (mean 14 months). No spacer-related complication (instability, dislodgment, severe wear, fracture) was observed. The range of motion of the knees remained unchanged between the first and second stages and improved after definitive reimplantation. The mean Knee Society Score at last-follow up was 88 points (knee score and functional score). The patients judged the result excellent (three), good (15), satisfactory (five), poor (one).
Conclusion The use of an articulating spacer in the two-stage treatment of infected TKR improves the quality of life of the patient, the ultimate range of motion, facilitates second-stage surgery and the functional recovery. Severe bone loss is a relative contraindication for articulating spacers, as these knee joints may require immobilisation during the resection time interval.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
