A unispacer is a small metallic wedge which is sometimes used in knee surgery to correct the deformity of a meniscectomy (removal of the meniscus) and improve the consequent imbalance of forces after meniscectomy.
Results of unispacer
The outcomes of the original metallic unispacer have not been good, but some researchers are working on a soft interpositional disc.
The Unispacer knee implant: early clinical results. Bailie AG, Lewis PL, Brumby SA, Roy S, Paterson RS and Campbell DG. J Bone Joint Surg Br. 2008 Apr;90(4):446-50. doi: 10.1302/0301-620X.90B4.20319.