Unicompartmental tibial hemiarthroplasty: early results of the UniSpacer knee.

An intra-articular metallic spacer is evaluated for the treatment of isolated medial compartment OA. It is proposed that this implant can provide axial correction for a varus deformity, eliminate the pseudolaxity of the MCL, improve knee function, maintain ROM, and provide pain relief. One-and 2-year data are presented on 71 UniSpacer Knee System implants that were implanted in 67 patients (four had bilateral surgeries). The mean age and weight of these patients was 54 years and 94 kg (207 lb), respectively. The heaviest patient in the group weighed 168 kg (370 lb). All knees were evaluated using the Knee Society clinical rating system, Lysholm scoring scale, radiographic limb alignment, and ROM. The mean Knee Society knee score improved 169% in the 1-year group and 193% in the 2-year group. The mean Knee Society function score improved 31% and 65%, respectively. The mean Lysholm score improved 88% and 140%, respectively. Five implants (7%) were revised to total knee arthroplasty (TKA) and 10 implants (14%) were revised to another UniSpacer Knee System implant. The early results suggest that an intra-articular metallic spacer is a viable treatment option for OA in the younger patient.