Unicompartmental Knee Arthroplasty: Survivorship and Risk Factors for Revision

Abstract

Background:Operative management for end-stage knee osteoarthritis (OA) primarily consists of arthroplasty. Total knee arthroplasty (TKA) is the so-called gold standard for multicompartmental OA. In selected patients, specifically those with unicompartmental OA and no definite contraindications, realignment osteotomies and unicompartmental knee arthroplasty (UKA) are viable options. UKA offers several advantages over TKA, including preservation of both cruciate ligaments, faster recovery, and less osseous resection. The purpose of this study was to determine the survivorship of UKAs and risk factors for all-cause revision surgery in patients with a minimum follow-up of 10 years in a large population-based database.Methods:We performed a population-based cohort study using linked administrative databases in Ontario, Canada. We identified all UKAs performed from January 2002 through December 2006. All patients had a minimum 10-year follow-up. Demographic data and outcomes were summarized using descriptive statistics. We used a Cox proportional hazards model with the Fine and Gray method accounting for competing risks such as death to analyze the effect of surgical and patient factors on the risk of revision of UKA.Results:A total of 4,385 patients were identified as having undergone primary UKA from 2002 through 2006 in Ontario. Of these patients, 779 underwent revision surgery, for a cumulative risk for all-cause revision of 16.5% at 10 years (95% confidence interval [CI]: 15.4% to 17.7%). Mechanical loosening was the reason for 83.4% of all revisions. Male sex, diabetes, an age younger than 50 years, and cementless implants were significant risk factors for revision surgery. Residence in a rural or urban setting, income quintile, discharge destination, and type of OA were not associated with the risk of revision. Survivorship at 1, 5, 10, and 15 years was 97.2%, 90.5%, 83.5%, and 81.9%, respectively.Conclusions:This study demonstrated a >80% long-term survivorship for UKA based on a large administrative database sample and identified important risk factors for failure including male sex, younger age, diabetes, and cementless fixation. This study found rates of survivorship similar to those previously reported in the literature, while identifying key risk factors for failure. Patient selection has always been identified as a key factor in ensuring successful UKA, and the risk factors identified in this study may help guide decision-making for surgeons and patients dealing with unicompartmental knee OA.Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Effect of tibial component overhang on survivorship in medial mobile-bearing unicompartmental knee arthroplasty

“…In the present study, we verified that excessive protrusion of the tibial implant could irritate the medial soft tissue and affect the functional prognosis of the patient [11,15]. All patients received a 94.9% survival rate during the follow up time, which is similar to the five-year revision rates of 87.5-90.5% reported by Moore et al and Ekhtiari et al [10,16]. Nevertheless, the postoperative revision rate in the major overhang group was a striking 20.9%, with the reasons for revision being bearing dislocation and aseptic loosening, respectively.…”

“…Although UKA has many advantages, the literature [2,[6][7][8] has shown that UKA has a higher revision rate than total knee arthroplasty (TKA). Common reasons for revision in UKA are knee pain, aseptic loosening of the component, progression of contralateral knee osteoarthritis, and bearing wear/dislocation [9,10]. However, fewer researchers have focused on the relationship between tibial component position and postoperative revision rates.…”

What’s New in Adult Reconstructive Knee Surgery

“…At a minimum follow-up of 10 years, a large population database study demonstrated that UKA survivorship was >80%, and mechanical loosening was responsible for 83.4% of revisions. Failure risk factors were younger age, diabetes, male sex, and cementless fixation 13 . In a retrospective study of lateral UKA, survivorship rates in patients ≥60 years of age were 98% at 5 years and 96% at 10 years.…”

Similar Survivorship but Different Revision Reasons for Uncemented Mobile-Bearing and Cemented Fixed-Bearing Medial UKA

“…However, UKA has a higher revision rate compared with total knee arthroplasty (TKA) 3-5 . Further research on risk factors, such as implant design and patient indications, and on reasons for revision 6,7 is needed to understand the higher risk of revision associated with UKA.…”

“…There is also ongoing debate regarding the ideal UKA patient profile [15][16][17] . While several studies have reported lower UKA survivorship in younger patients 6,7 and those with a higher body mass index (BMI) 18,19 , others have reported contrasting results 7,20,21 .…”