title: Unicompartmental knee arthroplasty: an intermediate report of survivorship after the introduction of a new system with analysis of failures.
abstract: We describe the outcome of a series of 66 consecutive porous coated low contact stress (LCS) unicompartmental knee arthroplasty (UKA) cases performed in 52 patients for osteoarthritis (OA) by a single surgeon. Both survival, using the endpoint of revision for any cause, and knee function, using the Oxford knee score (OKS) as a validated outcome measure, were established in a retrospective review. At an average postoperative follow-up period of 5.9 years (range 5.1-6.6), there were 8 knees in patients who had died and 58 knees in those who were still living. We established the status of all knees, and prosthesis survival at 5 years was 89.7% (95% confidence interval, 81.6% to 97.7%). Technical errors were responsible for four of six failures and included progression of lateral compartment OA due to overcorrection, a medial tibial stress fracture due to poor pin placement, and a case where cement was required and poor cementing technique lead to early tibial component loosening. In the remaining 52 knees, the average preoperative OKS had improved significantly (p<0.0001) from 37.0 (range, 17-49) to a postoperative score of 20.5 (range, 13-32). We conclude that the functional results following UKA compare favourably to total knee arthropasty (TKA); however, the survivorship of this series does not match that of published reports of TKA. The introduction of a new system of UKA includes the risk of early failures due to surgeon error, even when a surgeon is competent in UKA, warranting careful surveillance during this period.
authors.affiliation: SPORTSMED.SA, 32 Payneham Road, Stepney 5069, Adelaide, Australia.
authors.forename: Parminder J S
authors.initials: PJ
authors.lastname: Jeer
authors.forename: Gregory C R
authors.initials: GC
authors.lastname: Keene
authors.forename: Paul
authors.initials: P
authors.lastname: Gill
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D020099:Coated Materials, Biocompatible; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D017063:Outcome Assessment, Health Care; D011474:Prosthesis Design; D012086:Reoperation; D012189:Retrospective Studies
chemical_list: D020099:Coated Materials, Biocompatible