Cellbrick Knee Spacer

The Cellbrick Knee Spacer is a temporary knee prosthesis for skeletally mature patients undergoing two-stage knee replacement surgery to treat joint infections. It consists of a femoral spacer, tibial spacer, and optional canal rod, all designed with multiaperture features to carry antibiotic-loaded bone cement and release antibiotics at infection sites. The device is limited to 180 days of use, after which it must be explanted and replaced with a permanent implant or alternative treatment.

The femoral and tibial spacers are made of UHMWPE (ultra-high molecular weight polyethylene) with geometry based on cleared cruciate-retaining and ultra-congruent knee components. The optional canal rod is titanium alloy (Ti-6Al-4V). Key design features include multiaperture scaffolding to serve as a carrier for antibiotic-loaded cement, symmetric condyle design allowing left/right use, and five size options for anatomical variation. The device must be used with Palacos MV+G bone cement per validated antibiotic elution and fatigue testing.

ASTM F648/ISO 5834-2 for UHMWPE material; ASTM F136/ISO 5832-3 for titanium alloy. Testing conducted includes tibial spacer fatigue test, range of motion analysis, tibiofemoral constraint performance, wear testing, antibiotic release and in vitro testing, usability evaluation, and endotoxin testing.

The subject device is substantially equivalent to the primary predicate (COPAL knee moulds, K222570) because both are temporary implants (maximum 180 days) for skeletally mature patients requiring two-stage procedures for septic joint infection, with identical intended users, surgical procedures, body contact duration, and fixation methods. Although the subject device differs in material composition, appearance design, specifications, X-ray visibility, and sterilization method, evaluation and verification activities demonstrated equivalent safety and effectiveness with no new risks compared to predicate devices. The femoral spacer geometry is identical to a cleared cruciate-retaining component, and the tibial spacer bearing surface matches cleared ultra-congruent tibial inserts.