Novel post-cam endoskeleton-reinforced posterior-stabilized cement articulating spacer reduced the rate of mechanical complications in prosthetic knee infection.

BACKGROUND

Posterior-stabilized cement articulating spacers (PS spacers) have superior knee scores and a greater range of motion in a two-stage exchange for chronic prosthetic knee infections (PKIs); however, mechanical complications are associated with the use of PS spacers. In the present study, we investigated a novel post-cam endoskeleton-reinforced PS spacer and its outcomes.

METHODS

This single-surgeon retrospective cohort study included patients with chronic PKIs treated with PS spacers between 2015 and 2022. PS spacers with three different configurations, based on endoskeleton reinforcement, were compared: non-reinforced (n-PS), cam-reinforced alone (C-PS), and post- and cam-reinforced (PC-PS). Rates of mechanical complications, reoperation, and infection eradication were evaluated. The constraint choice of the revision prosthesis and risk factors for mechanical complications were analysed.

RESULTS

In total, 186 patients, including 75 with n-PS, 61 with C-PS, and 50 with PC-PS spacers, were included. All patients were followed up for 2 years. The rate of overall mechanical complications was lowest in patients treated with PC-PS spacers, particularly in patients with unstable joints after femoral cam and tibial post fracture and tibial spacer dislodgement. Moreover, neither spacer exchange nor rotating-hinge knee revision prosthesis was required in PC-PS spacers. Independent risk factors for mechanical complications were body mass index ≥ 25 kg/m2, femoral spacer size ≤ 2, and intra-operative maximum flexion ≥ 110°.

CONCLUSION

The novel PC-PS spacers prevented mechanical complications, spacer exchange, and the need for high-level constraint revision prostheses. We recommend the use of novel PC-PS spacers in two-stage exchange for chronic PKIs, especially in patients with a high body mass index, small femoral spacer size, and high knee flexion.