Unicompartmental Knee Arthroplasty Relieves Pain and Improves Function More Than Total Knee Arthroplasty

Center for Hip and Knee Replacement, New York–Presbyterian Hospital at Columbia University, New York, New York 10032, USA.
The Journal of arthroplasty (Impact Factor: 2.67). 05/2012; 27(8 Suppl):99-105. DOI: 10.1016/j.arth.2012.03.044
Source: PubMed


This study compared outcomes as assessed by 12-item Short-Form Health Survey (SF-12) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) between patients who underwent unicompartmental (UKA) and patients who underwent total knee (TKA) arthroplasty. We prospectively collected preoperative demographic and SF-12 and WOMAC data on 128 TKAs and 70 UKAs. Postoperatively, SF-12 and WOMAC outcomes were recorded during annual follow-up visits. At baseline, patients who underwent UKA had a higher Charlson Comorbidity Index than patients who underwent TKA; otherwise, preoperative characteristics were similar. At a mean follow-up of 3.0 years for UKA and 2.9 years for TKA, patients who underwent UKA reported higher SF-12 physical component and mental component scores and WOMAC pain/stiffness/physical function scores (confirmed with multivariate analysis). Furthermore, patients who underwent UKA had significantly larger improvements in both SF-12 outcomes and WOMAC pain and physical function scores from baseline than did patients who underwent TKA.

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    • "Unicompartmental Knee Replacement (UKR) comprises between 5% and 10% of all knee replacements recorded each year in national joint registries (NJRs), but up to 50% may be eligible on the basis of disease pattern1–4. By only replacing the damaged parts of the knee, preserving normal structures such as the anterior cruciate ligament (ACL), UKR restores normal knee kinematics, restoring more normal knee function than is possible with total knee replacement (TKR)5,6. Patients undergoing UKR recover more quickly, and have less perioperative morbidity and mortality compared to TKR, probably due to the reduced soft tissue disruption and blood loss in UKR7–9. "
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    ABSTRACT: Objective Unicompartmental Knee Replacement (UKR) has important advantages over total knee replacement (TKR) but has a higher revision rate. Outcomes vary between centres, suggesting that risk factors for revision may be modifiable with changes to patient selection or operative technique. The objective of this study was to determine factors affecting revision, patient-reported outcome and satisfaction following UKR. Method 25,982 cases from three national databases were analysed. Multilevel multivariable regression models were used to examine the effect of patient and surgical factors on implant survival, patient-reported outcome and satisfaction at six months and eight years following UKR. Results Of the 25,982 cases, 3,862 (14.9%) had pre-operative and six-month Oxford Knee Scores (OKS). Eight-year survival was 89.1% (95% CI 88.3-89.9). OKS increased from 21.9 (SD 7.6) to 37.5 (SD 9.5). Age (HR 0.96 (95%CI 0.96-0.97) per year), male gender (HR 0.86 (95%CI 0.76-0.96)), unit size (HR 0.92 (95%CI 0.86-0.97) per case up to 40 cases/year) and operating surgeon grade (HR 0.78 (95%CI 0.67-0.91) if consultant) predicted improved implant survival. Older patients (≤75 years), and those with lower deprivation levels had superior OKS and satisfaction (adjusted mean difference 0.14 (95%CI 0.09-0.20) points per year of age and 0.93 (95%CI 0.60-1.27) per quintile of deprivation). Ethnicity, anxiety and co-morbidities also affected patient-reported outcome. Conclusions This study has identified important predictors of revision and patient-reported outcome following UKR. Older patients, who are least likely to be offered UKR, may derive the greatest benefits. Improved understanding of these factors may improve the long-term outcomes of UKR.
    Full-text · Article · Sep 2014 · Osteoarthritis and Cartilage
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    ABSTRACT: Purpose: C-reactive protein (CRP) is an acute-phase biomarker responding to surgical trauma. Typically, a first peak is observed at day 2 with a reduction at day 4 and normalization 3-6 weeks after surgery. CRP is often linked to prosthetic joint infection when elevated values are present longer time after surgery. The aim of this study was to analyse the kinetics of CRP in different types of minimally invasive (MI) arthroplasty and to observe if there were significant differences in between MI total knee arthroplasty (TKA), patient-specific instruments (PSI) TKA and unicompartmental arthroplasty (UKA). Materials and methods: Three hundred and seventy-two patients were prospectively studied with a blood test measuring CRP at day 2, 4, 21 and 42 in 3 different groups of patients: 257 MI TKA, 55 PSI TKA and 60 UKA. Mean peak values and kinetics were compared in between different groups of MI arthroplasty. Results: There was a significant age difference in the three MI arthroplasty groups. The difference in mean age for the conventional MI TKA group of 68.8 ± 9.8 years, 58.5 ± 11.7 years for the unicompartmental group (P < 0.05) and 63.3 ± 9.6 years for the PSI group (P < 0.05) was significant. Mean CRP level, for the entire study group, on day 2 was 16.7 ± 8.8 mg/dl that gradually decreased to 13.6 ± 7.8 mg/dl on day 4. On day 21 and 42, median CRP level was 0.6 (0-20) and 0.4 (0-7) mg/dl, respectively. Peak CRP values were lower for UKA compared to TKA at day 2 (11.6 vs. 17.5 mg/dl) and day 4 (8.0 vs. 15 mg/dl), but this was not observed for PSI-assisted arthroplasty (18.9 vs. 17.5 mg/dl). There was a trend for faster CRP normalization in UKA compared to the two other groups at day 21 and at day 42 and for PSI TKA to have a lower mean level at 4 days (12.9 vs. 15 mg/dl). There was no statistical difference in the normalization rate of PSI-assisted versus MI TKA. Conclusion: Kinetics of CRP in MI arthroplasty are identical to the published kinetics of conventional TKA. Most patients normalize CRP at 3 weeks; however, 18 % does not by 6 weeks. This is not a sign of early prosthetic joint infection. Peak values are significantly lower for UKA but not for PSI TKA.
    No preview · Article · Dec 2012 · Knee Surgery Sports Traumatology Arthroscopy
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    ABSTRACT: Indications for UKA for isolated osteoarthritis of the knee remain controversial. Two hundred twenty-nine UKA that were performed at our institution were evaluated for which factors were associated with a poor outcome. BMI >35 was correlated with lower KSS scores than patients with BMI <35. In contrast to prior reports, patients younger than 60 years old had higher scores than patients 60 years and older at 2 years. Women had an unacceptably high short-term revision rate for any reason of 6.5%. Popularity for UKA has increased, and a more in depth investigation of predictors of poor outcomes demonstrates that younger patients appear to have better results. Obese patients continue to improve up to 2 years after surgery and should not be precluded from undergoing UKA.
    No preview · Article · Mar 2013 · The Journal of arthroplasty
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