Revision Of Unicompartmental Knee Arthroplasty Research Articles

Accuracy and completeness of registry-reported unicompartmental knee arthroplasty revision.

The key outcome of joint registries is revision events, which inform clinical practice and identify poor-performing implants. Registries record revision events and reasons, but accuracy may be limited by a lack of standardized definitions of revision. Our study aims to assess the accuracy and completeness of unicompartmental knee arthroplasty (UKA) revision and indications reported to the New Zealand Joint Registry (NZJR) with independent clinical review. Case record review of 2272 patients undergoing primary UKA at four large tertiary hospitals between 2000 and 2017 was performed, identifying 158 patients who underwent revision. Detailed review of clinical findings, radiographs and operative data was performed to identify revision cases and the reasons for revision using a standardized protocol. These were compared to NZJR data using chi-squared and Fisher exact tests. The NZJR recorded 150 (95%) of all UKA revisions. Osteoarthritis progression was the most common reason on the systematic clinical review (35%), however, this was underreported to the registry (8%, P < 0.001). A larger proportion of revisions reported to the registry were for 'pain' (30% of cases vs. 5% on clinical review, P < 0.001). A reason for revision was not reported to the registry for 10% of cases. The NZJR had good capture of UKA revisions, but had significant differences in registry-reported revision reasons compared to our independent systematic clinical review. These included over-reporting of 'pain', under-reporting of osteoarthritis progression, and failing to identify a revision reason. Efforts to improve registry capture of revision reasons for UKA could be addressed through more standardized definitions of revision and tailored revision options for UKA on registry forms.

Unexpected positive cultures in revision total knee arthroplasty after unicompartmental knee arthroplasty.

Unexpected positive cultures are defined as a single positive culture in intraoperative samples taken during revision surgery after prosthetic joint infection was preoperatively ruled out. This study aims to determine the prevalence of unexpected positive cultures (UPC) in revision total knee arthroplasty (TKA) after unicompartmental knee arthroplasty (UKA). As a secondary objective, this study aims to compare the re-intervention rate in this specific group, between UPC and non-UPC patients. The hypothesis is that the UPC prevalence in patients who undergo a revision TKA after UKA is not higher than in other TKA revision cases and this does not increase the risk of re-intervention. This is a retrospective study where all patients who underwent a UKA revision from January 2016 to February 2023 in a high-volume arthroplasty centre, were analyzed. Unexpected positive culture prevalence in this group of patients was obtained. During the included period, 270 UKA revision surgeries were performed. Eight cases had at least two positive cultures and were therefore excluded. The final analysis included 262 patients. Of these, 8 (3.05%) patients presented UPCs and the isolated microorganisms were low-virulence organisms. None of the UPC patients received any treatment. No statistical differences were found between UPC and non-UPC groups in the analyzed variables. The prevalence of unexpected positive cultures in patients following revision of unicompartmental knee arthroplasty is lower than in patients who undergo a revision of total knee arthroplasty. In UKA patients a UPC does not seem to increase the risk of a re-intervention, so it can be safely ignored if ICM criteria are not met.

Functional outcomes and return to sports, work, and daily activities after revision UKA compared to primary UKA and TKA

Unicompartmental knee arthroplasty (UKA), in addition to total knee arthroplasty (TKA), has been shown to be effective in the surgical treatment of knee osteoarthritis with appropriate patient selection. In clinical studies, it has demonstrated superior functional results with lower complication rates. In clinical practice, these advantages must be weighed against the disadvantage of an increased revision rate, especially in younger patients with sports and work activities. The aim of this study was to compare the functional outcome as well as the time to return to daily activities, work, and sports after revision of UKA to TKA with those of primary UKA and primary TKA using amatched-pair analysis. The study was based on amatched-pair analysis at two defined time points, always comparing 28patients who underwent either revision of aUKA to aTKA, primary UKA, or primary TKA. Patients completed the Oxford Knee Score, UCLA score, Knee Society score, and WOMAC score during standardized follow-up. In addition, postoperative patient satisfaction and return to activities of daily living, work, and sports were recorded in astandardized manner, and aclinical examination was performed. The four functional scores studied showed acommon trend in favor of UKA, followed by primary TKA and revision TKA. The differences between converted UKA and primary TKA were not significant. However, at 3.2years after the last surgery, the results of the converted UKA were significantly lower than those of the primary UKA. Return to work and sports tended to occur the earliest after UKA, followed by TKA and the revision group. All groups showed atendency to engage in low-impact sports. The functional results of revised UKA were significantly inferior to those of primary UKA based on a3-year follow-up. Return to work, sports, and activities of daily living tended to take longer after revision than after primary implantation of either aUKA or aTKA.

Does changes in unicompartmental knee arthroplasty practice pattern influence reasons for revision?

The aim of this study was to describe the pattern of revision indications for unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) and any change to this pattern for UKA patients over the last 20 years, and to investigate potential associations to changes in surgical practice over time. All primary knee arthroplasty surgeries performed due to primary osteoarthritis and their revisions reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were included. Complex surgeries were excluded. The data was linked to the National Patient Register and the Civil Registration System for comorbidity, mortality, and emigration status. TKAs were propensity score matched 4:1 to UKAs. Revision risks were compared using competing risk Cox proportional hazard regression with a shared γ frailty component. Aseptic loosening (loosening) was the most common revision indication for both UKA (26.7%) and TKA (29.5%). Pain and disease progression accounted for 54.6% of the remaining UKA revisions. Infections and instability accounted for 56.1% of the remaining TKA revision. The incidence of revision due to loosening or pain decreased over the last decade, being the second and third least common indications in 2017. There was a decrease associated with fixation method for pain (hazard ratio (HR) 0.40; 95% confidence interval (CI) 0.17 to 0.94) and loosening (HR 0.29; 95% CI 0.10 to 0.81) for cementless compared to cemented, and units UKA usage for pain (HR 0.67, 95% CI 0.50 to 0.91), and loosening (HR 0.51; 95% CI 0.37 to 0.70) for high usage. The overall revision patterns for UKA and TKA for the last 20 years are comparable to previous published patterns. We found large changes to UKA revision patterns in the last decade, and with the current surgical practice, revision due to pain or loosening are significantly less likely.

Unicompartmental knee arthroplasties: does the type of tibial component selected influence implant survival?

Few information has been published on the survival of unicompartmental knee arthroplasty (UKA) and fixed-bearing tibial components. The aim of this study is to analyze if UKA survival varies according to UKA model used and to analyze the possible risk factors for UKA revision. A retrospective study analyzing 301 UKAs (ACCURIS, all-polyethylene tibial component, 152; Triathlon PKR, metal-backed tibial component, 149) was performed. Demographic parameters as well as implant survival and cause of prosthetic revision were analyzed. The Kaplan-Meier survival analysis, the log-rank test and the Cox multiple regression were used for the analysis. Average follow-up was 8.1 ± 3.08-years. Average age was 68.1 ± 8.6-years; 70.4% of subjects were women. The ACCURIS UKA group had a UKA revision rate higher compared to the Triathlon PKR group (16/152, 10.6% vs 5/149, 3.4%, respectively; p < 0.001). The main cause of prosthetic revision was aseptic loosening (5/21, 23.8%). All aseptic loosening cases and tibial component collapse were reported with the ACCURIS UKA group. Overall UKA survival was 98.01% (95% CI 95.62-99.1) at 1-year, 94.27% (95% CI 90.95-96.4) at 5-years and 92.38% (95% CI 88.48-94.99) at 10-years' follow-up. There were no differences in the Kaplan-Meier survival curves regarding operated side or affected tibiofemoral compartment (log-rank test = 0.614 and 0.763, respectively). However, Kaplan-Meier survival curve according to UKA model used was different (log-rank test = 0.033). The metal-backed component appeared to be a protector factor for UKA revision when adjusted for age, sex, operated side, and affected tibiofemoral compartment (Hazard Ratio 0.32, p = 0.031). Fixed-bearing UKAs showed excellent mid- and long-term survival rates. Aseptic loosening is the main cause of implant failure. PKR group (metal-backed component) seem to be a protector factor to UKA revision when it was compared with ACCURIS UKA group (all-polyethylene tibial component).

THE LIFETIME REVISION RISK OF UNICOMPARTMENTAL KNEE ARTHROPLASTY

Unicompartmental knee arthroplasty (UKA) is associated with a higher risk of revision compared with total knee arthroplasty (TKA). The outcomes of knee arthroplasty are typically presented as implant survival or incidence of revision after a set number of years, which can be difficult for patients and clinicians to conceptualise. We aimed to calculate the ‘lifetime risk’ of revision for UKA as a more relatable estimate of risk projection over a patient's remaining lifetime, and make comparisons to TKA. All primary UKAS performed from 1999 to 2019 (n=13,481) captured by the New Zealand Joint Registry (NZJR) were included. The lifetime risk of revision was calculated and stratified by age, gender and American Society of Anesthesiologists (ASA) status. The lifetime risk of revision for UKA was highest in the youngest patients (46-50 years; 40.4%) and lowest in the oldest patients (86-90 years; 3.7%). Lifetime risk of revision was higher for females (range 4.3%-43.4% cf. males 2.9%-37.4%) and patients with higher ASA status (ASA 3-4 range 8.8%-41.2% cf. ASA 1 1.8%-29.8%), regardless of age. The lifetime risk of UKA was two-fold higher than TKA (ranging from 3.7%-40.4% UKA, 1.6%-22.4% TKA) across all age groups. Increased risk of revision in the younger patients was associated with aseptic loosening in both males and females, and pain in females. Periprosthetic joint infections (PJI) accounted for 4% of all UKA revisions, in contrast to 27% for TKA; risk of PJI was higher for males than females for both procedures. The lifetime risk of revision is a more meaningful measure of arthroplasty outcomes and can aid with patient counselling prior to UKA. Findings from this study show the increased lifetime risk of UKA revision for younger patients, females and those with higher ASA status.

Similar Survivorship but Different Revision Reasons for Uncemented Mobile-Bearing and Cemented Fixed-Bearing Medial UKA: A Long-Term Population-Based Cohort Study of 2,015 Patients.

Long-term survivorship and accurate characterization of revision reasons in unicompartmental knee arthroplasty (UKA) are limited by a lack of long-term data and standardized definitions of revision. The aim of this study was to identify survivorship, risk factors, and reasons for revision in a large cohort of medial UKAs with long-term follow-up (up to 20 years). Patient, implant, and revision details for 2,015 primary medial UKAs (mean follow-up, 8 years) were recorded following systematic clinical and radiographic review. Survivorship and risk of revision were analyzed using Cox proportional hazards. Reasons for revision were analyzed using competing-risk analysis. Implant survivorship at 15 years was 92% for cemented fixed-bearing (cemFB), 91% for uncemented mobile-bearing (uncemMB), and 80% for cemented mobile-bearing (cemMB) UKAs (p = 0.02). When compared with cemFB, the risk of revision was higher for cemMB implants (hazard ratio [HR] = 1.9, 95% confidence interval [CI] = 1.1 to 3.2; p = 0.03). At 15 years, cemented implants had a higher cumulative frequency of revision due to aseptic loosening (3% to 4%, versus 0.4% for uncemented; p < 0.01), cemMB implants had a higher cumulative frequency of revision due to osteoarthritis progression (9% versus 2% to 3% for cemFB/uncemMB; p < 0.05), and uncemMB implants had a higher cumulative frequency of revision due to bearing dislocation (4% versus 2% for cemMB; p = 0.02). Compared with the oldest patients (≥70 years), younger patients had a higher risk of revision (<60 years: HR = 1.9, 95% CI = 1.2 to 3.0; 60 to 69 years: HR = 1.6, 95% CI = 1.0 to 2.4; p < 0.05 for both). At 15 years, there was a higher cumulative frequency of revision for aseptic loosening in these younger groups (3.2% and 3.5% versus 2.7% for ≥70 years; p < 0.05). Implant design and patient age were risk factors for revision of medial UKA. The findings from this study suggest that surgeons should consider using cemFB or uncemMB designs because of their superior long-term implant survivorship compared with cemMB designs. Additionally, for younger patients (<70 years), uncemMB designs had a lower risk of aseptic loosening than cemFB designs at the expense of a risk of bearing dislocation. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Research progress of failure and revision of unicompartmental knee arthroplasty

To conclude the failure factors of unicompartmental knee arthroplasty (UKA), and summarize the research progress of revision surgery. The literature on UKA at home and abroad in recent years was reviewed to summarize its risk factors, treatment methods, including the evaluation of bone loss, prosthesis selection, and surgical techniques. The factors inducing UKA failure mainly include improper indications, technical errors, and others. The application of digital orthopedic technology can reduce failures caused by surgical technical errors and shorten the learning curve. There are a variety of options for revision surgery after UKA failure, including polyethylene liner replacement, revision with UKA or total knee arthroplasty, with adequate preoperative evaluation prior to implementation. The biggest challenge in revision surgery is the management and reconstruction of bone defects. There is a risk of failure in UKA, which needs to be treated with caution and should be determined according to the type of failure.

THE LIFETIME REVISION RISK OF KNEE ARTHROPLASTY

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New ZealandOutcomes following knee arthroplasty are typically defined as implant survivorship at defined timepoints, or revision incidence over time. These estimates are difficult to conceptualise, and lack context for younger patients with more remaining years of life. We therefore aimed to determine a ‘lifetime’ risk of revision as a more useful metric for total (TKA) and unicompartmental knee arthroplasty (UKA).The New Zealand Joint Registry was used to identify 96,497 primary TKAs and 13,481 primary UKAs performed between 1999 and 2019. Patient mortality and revision incidence were also extracted. Estimates of lifetime risk were calculated using an actuarial lifetable method. The estimates were stratified by age and gender. Reasons for revision were categorised using previously published standardised definitions.The lifetime risk of UKA revision was two-fold higher than TKA across all age groups (range 3.7-40.4% UKA, 1.6-22.4% TKA). Revision risk was higher for males with TKA (range 3.4%-25.2% males, 1.1%-20% females), but higher for females with UKA (range 4.3%-43.4% vs. 2.9%-37.4% for males). Revision due to infections were higher for TKA (1.5% males, 0.7% females) compared with UKA (0.4% males, 0.1% females). The increased risk in younger UKA patients was associated with higher incidence of aseptic loosening (UKA 2%, TKA 1%) and ‘unexplained pain’ (UKA 2%, TKA 0.2%).The risk for UKA was two-fold higher than TKA, and this was partially explained by a higher proportion of revisions due to ‘unexplained pain’. For TKA, males had higher risk of revision, in contrast to UKA where females had higher risk; this gender difference was associated with higher incidence of infections with TKA. Younger age, gender and higher ASA status were also associated with increased lifetime risk of UKA revision. Lifetime risk of revision can provide a meaningful measure of arthroplasty outcomes to aid patient counselling.

COMPARISON OF REVISION ‘THRESHOLDS’ USING PATIENT-REPORTED OUTCOMES FOLLOWING TOTAL AND UNICOMPARTMENTAL KNEE ARTHROPLASTY

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New ZealandPatient reported outcome measures (PROMs) are predictors of knee arthroplasty revision. Unicompartmental knee arthroplasty (UKA) is effective for patients with the correct indications, however has higher revision rates than total knee arthroplasty (TKA). Different revision thresholds for the procedures have been postulated. Our aims were to investigate: 1) if PROMs could predict knee arthroplasty revision within two years of the score at six months, five years and ten years follow-up, and 2) if revision ‘thresholds’ differed between TKA and UKA.All TKAs and UKAs captured by the New Zealand Joint Registry between 1999 and 2019 with at least one OKS response at six months (TKA n=27,708, UKA n=8,415), five years (TKA n=11,519, UKA n=3,365) or ten years (TKA n=6,311, UKA n=1,744) were included. were propensity-score matched 2:1 with UKAs for comparison of revision thresholds.Logistic regression indicated that for every one-unit decrease in OKS, the odds of TKA and UKA revision decreased by 10% and 11% at six months, 10% and 12% at five years and 9% and 5% at ten years. Fewer TKA patients with ‘poor’ outcomes (≤25) subsequently underwent revision compared with UKA at six months (5.1% vs. 19.6%, p&lt;0.001), five years (4.3% vs. 12.5%, p&lt;0.001) and ten years (6.4%vs. 15.0%, p=0.02). Compared with TKA, UKA patients were 2.5 times more likely to undergo revision for ‘unknown’ reasons, bearing dislocations and disease progression.The OKS is a strong predictor of subsequent knee arthroplasty revision within two years of the score from early to late term. A lower revision threshold was found with UKA when compared with a matched TKA cohort. Higher revision rates of UKA are associated with both lower clinical thresholds for revision and additional modes of UKA failure.

Reduced 5-Year Risk for Revision of the Oxford UKA Using New Instrumentation versus Conventional Instrumentation: A Registry Study of 12,867 UKAs.

Microplasty instrumentation was introduced for a more consistent surgical implantation technique, especially component alignment and tibial resection level, of the Oxford medial unicompartmental knee arthroplasty (UKA) and thereby aims to improve UKA survival. This study aimed to assess the 5-year risk for revision and reasons for revision of the Oxford medial UKA using the new instrumentation (Microplasty) with its predecessor, that is, conventional instrumentation (Phase 3). Data of all medial UKAs from the Dutch Arthroplasty Register (Landelijke Registratie Orthopedische Implantaten) between 2007 and 2019 were collected. Type of instrumentation was divided into new (Microplasty) and conventional instrumentation. Kaplan-Meier analysis was performed to calculate 5-year cumulative revision percentage with any reason for revision as end point. A multivariable Cox regression with outcome revision of UKA adjusted for age, gender, American Society of Anesthesiologists score, surgical history, and type of fixation was performed. Additionally, reasons for revision at 3-year were assessed and tested through Fisher's exact tests. A total of 12,867 Oxford medial UKAs, 8,170 using new and 4,697 using conventional instrumentation, were included. The 5-year revision percentage was 9.2% (95% confidence interval [CI]: 8.4-10.1%) for UKAs using the conventional and 6.1% (95% CI: 5.4-6.7%) for new instrumentation. The adjusted hazard ratio for revision at 5-year follow-up was 0.74 (95% CI: 0.63-0.87) in favor of UKAs using the new instrumentation. Malalignment was more frequently registered as reason for revision in UKAs using the conventional compared with the new instrumentation (16% versus 7.5%; p = 0.001). Our results show a reduced 5-year risk for revision of the medial Oxford UKAs using the new compared with the conventional instrumentation. This might be the result of a lower revision rate for malalignment in UKAs using the new instrumentation.

The lifetime revision risk of unicompartmental knee arthroplasty.

Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the 'lifetime risk' of revision for UKA as a more meaningful estimate of risk projection over a patient's remaining lifetime, and to compare this to TKA. Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade. The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures. Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J2022;104-B(6):672-679.

Optimized medial unicompartmental knee arthroplasty outcome: learning from 20 years of propensity score matched registry data.

Background and purposeUnicompartmental knee arthroplasty (UKA) has increased in use. We investigated changes to UKA revision risk over the last 20 years compared with total knee arthroplasty (TKA), examined external and patient factors for correlation to UKA revision risk, and described the survival probability for current UKA and TKA practice.Patients and methodsAll knee arthroplasties reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were linked to the National Patient Register and the Civil Registration System for comorbidity, emigration, and mortality information. All primary UKA and TKA patients with primary osteoarthritis were included and propensity score matched 4 TKAs to 1 UKA. Revision and mortality were analyzed using competing risk cox regression with a shared gamma frailty component.ResultsThe matched cohort included 48,195 primary knee arthroplasties (9,639 UKAs). From 1997–2001 to 2012–2017 the 3-year hazard ratio decreased from 5.5 (95% CI 2.7–11) to 1.5 (CI 1.2–1.8) due to increased UKA survival. Cementless fixation, a high percentage usage of UKA, and increased surgical volume decreased UKA revision risk, and increased in occurrence parallel to the decreasing revision risks. Current UKA practice using cementless fixation at a high usage unit has a 3-year implant survival of 96% (CI 97–95), 1.1% lower than current TKA practice.InterpretationUKA revision risk has decreased over the last 20 years, nearing that of TKA surgery. High usage rates, surgical volume, and the use of cementless fixation have increased during the study and were associated with decreased UKA revision risks.

Fast-track revision knee arthroplasty.

BackgroundLimited data exist on fast-track protocols in relation to revision knee arthroplasty. Hence, the aim of this study was to report length of stay (LOS), risk of LOS > 5 days and readmission ≤ 90 days after revision knee arthroplasty in centers with a well-established fast-track protocol in both primary and revision surgery. MethodsAn observational cohort study from the Centre for Fast-track Hip and Knee Replacement and the Danish Knee Arthroplasty Register. We included elective aseptic major component revision knee arthroplasties consecutively from 6 dedicated fast-track centers from 2010 to 2018. Results1439 revision knee arthroplasties were analyzed, including 900 total revisions, 171 large partial revisions (revision of either femoral or tibia component) and 368 revisions of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA). Mean age was 65 years (SD 10.9) and 66% were females. Mean LOS was 3.7 days (SD 3.9) in the study period, but decreased to 2.4 days (SD 1.3) in 2018. Risk factors for LOS > 5 days was ≥ 1 previous revision, use of walking aid, BMI > 35, ages < 50, 70–79 and ≥ 80 years, whereas revision of UKA to TKA and large partial revision were negatively associated. The 90-day readmission and mortality risk was 9.1% and 0.5%. Cardiac disease and use of walking aid were associated with increased risk of readmission ≤ 90 days. ConclusionElective aseptic major component revision knee arthroplasty using similar fast-track protocols as in primary TKA is safe with short and decreasing LOS.

Unicompartmental Knee Arthroplasty: Survivorship and Risk Factors for Revision: A Population-Based Cohort Study with Minimum 10-Year Follow-up.

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. 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. 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. 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. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

High usage of medial unicompartmental knee arthroplasty negatively influences total knee arthroplasty revision rate

PurposeSurgeons with higher medial unicompartmental knee arthroplasty (UKA) usage have lower UKA revision rates. However, an increase in UKA usage may cause a decrease of total knee arthroplasty (TKA) usage. The purpose of this study was to investigate the influence of UKA usage on revision rates and patient-reported outcomes (PROMs) of UKA, TKA, and combined UKA + TKA results.MethodsUsing the New Zealand Registry Database, surgeons were divided into six groups based on their medial UKA usage: < 1%, 1–5%, 5–10%, 10–20%, 20–30% and > 30%. A comparison of UKA, TKA and UKA + TKA revision rates and PROMs using the Oxford Knee Score (OKS) was performed.ResultsA total of 91,895 knee arthroplasties were identified, of which 8,271 were UKA (9.0%). Surgeons with higher UKA usage had lower UKA revision rates, but higher TKA revision rates. The lowest TKA and combined UKA + TKA revision rates were observed for surgeons performing 1–5% UKA, compared to the highest TKA and UKA + TKA revision rates which were seen for surgeons using > 30% UKA (p < 0.001 TKA; p < 0.001 UKA + TKA). No clinically important differences in UKA + TKA OKS scores were seen between UKA usage groups at 6 months, 5 years, or 10 years.ConclusionSurgeons with higher medial UKA usage have lower UKA revision rates; however, this comes at the cost of a higher combined UKA + TKA revision rate that is proportionate to the UKA usage. There was no difference in TKA + UKA OKS scores between UKA usage groups. A small increase in TKA revision rate was observed for high-volume UKA users (> 30%), when compared to other UKA usage clusters. A significant decrease in UKA revision rate observed in high-volume UKA surgeons offsets the slight increase in TKA revision rate, suggesting that UKA should be performed by specialist UKA surgeons.Level of evidenceIII, Retrospective therapeutic study.

Sensor guided unicompartmental to total knee arthroplasty revision: Surgical technique.

Unicompartmental Knee Arthroplasty (UKA) is an effective surgical option for managing unicompartmental knee osteoarthritis; it represents 10% of all knee arthroplasties worldwide, increasing 32.5% annually in the United States alone. Despite evolution in surgical technique and implant design, success rate and long-term survivorship of UKA have been historically lower than Total Knee Arthroplasty (TKA). The most common causes of UKA failure leading to revision are polyethylene wear, progression of arthritis, aseptic loosening and patella-femoral symptoms due to poor patient selection in many cases. Historically, UKA revisions have presented technical challenges mainly related to managing residual bone defects and ligament insufficiency ultimately leading to knee instability: the fear of instability has often pushed surgeons to lower the threshold for an increase of the intra-articular level of constraint. Unfortunately, the use of more constrained implants requires sacrificing bone stock and has been related to higher rates of re-revision secondary to recurrence of aseptic loosening. Because of these challenges, the authors developed a surgical technique that could combine balancing the knee during revision surgery with the use of the less constrained polyethylene option. To achieve this, we started evaluating a novel device (VERASENSE, Orthosensor, FL) designed to support soft tissue balancing during primary TKA. This intraoperative sensing technology dynamically quantifies intra-articular loads during TKA trial with the goal of correcting any residual imbalance in real time. Herein we propose a novel surgical technique, which might allow use of a primary TKA design characterized by a lower level of constraint, instead of a constrained or hinged revision knee system, during UKA revision. A key aspect of this technique is the use of sensing technology during intraoperative stability testing.

Stiffness after unicompartmental knee arthroplasty: Risk factors and arthroscopic treatment.

Introduction: One of the principal complications after total knee arthroplasty (TKA) is stiffness. There are no publications concerning stiffness after unicompartmental knee arthroplasty (UKA). Study objectives were to describe the incidence of stiffness after UKA, to look for risk factors, and to describe safe and effective arthroscopic treatment. Methods: There were 240 UKA performed between March 2016 and January 2019 included. Robotic-assisted surgery was performed in 164 patients and mechanical instrumentation in 76 patients. Stiffness was defined as flexion < 90° or a flexion contracture > 10° during the first 45 post-operative days. Patients with stiffness were treated with arthroscopic arthrolysis. Several factors were studied to look for risk factors of stiffness: body mass index, gender, age, mechanical or robotic instrumentation, preoperative flexion, previous meniscectomy, and anticoagulant treatment. Arthrolysis effectiveness was evaluated by flexion improvement and UKA revision rate. Results: 22 patients (9%) developed stiffness. Mechanical instrumentation significantly increased the risk of stiffness with OR = 0.26 and p = 0.005. Robotic-assisted surgery decreased the risk of stiffness by five-fold. Before arthrolysis, mean knee flexion was 79°, versus 121° (53% improvement) after arthroscopic arthrolysis. Only 2 patients (9%) underwent UKA revision after arthrolysis. Discussion: Stiffness after UKA is an important complication with an incidence of 9% in this study. Arthroscopic arthrolysis is a safe and effective treatment with a range of motion improvement of > 50%. Robotic-assisted surgery significantly decreases the risk of postoperative stiffness.Level of evidence: Level III, therapeutic study, retrospective cohort study

Unicompartmental knee arthroplasty and revision total knee arthroplasty have a lower risk of venous thromboembolism disease at 30\u2009days than primary total knee arthroplasty

BackgroundWhile multiple studies have demonstrated a lower venous thromboembolism disease (VTED) risk for unicompartmental knee arthroplasty (UKA) compared to primary total knee arthroplasty (TKA), recent reports have shown that revision TKA also had a lower VTED risk compared to primary TKA, an unexpected finding because of its theoretical increased risk. Given the paucity of up-to-date comparative studies, our goal was to perform a high-powered VTED risk comparison study of UKA and revision TKA to primary TKA using recent data.MethodsThe National Surgical Quality Improvement Program (NSQIP) database was queried between 2011 and 2018, and we identified 213,234 patients for inclusion: 191,810 primary TKA, 9294 UKA, and 12,130 revision TKA. Demographics, medical comorbidities, and possible VTE risk factors were collected. Thirty-day outcomes, including deep vein thrombosis (DVT), pulmonary embolism (PE), and all-cause VTED were compared between knee arthroplasty types.ResultsOn multivariate analysis, UKA was significantly associated with lower rates of DVT [OR 0.44 (0.31–0.61); P < 0.001], PE [OR 0.42 (0.28–0.65); P < 0.001], and all-cause VTED [OR 0.42 (0.32–0.55); P < 0.001] when compared to primary TKA. Revision TKA was significantly associated with lower rates of PE [OR 0.62 (0.47–0.83); P = 0.002], and all-cause VTED [OR 0.82 (0.70–0.98); P = 0.029] when compared to primary TKA.ConclusionsUtilizing recent data from a nationwide patient cohort and controlling for confounding variables, our results showed that both revision TKA and UKA had a lower risk of VTED compared to primary TKA, corroborating the results of recent investigations. Additional prospective investigations are needed to explain this unexpected result.

High Prevalence of Radiographic Outliers and Revisions with Unicompartmental Knee Arthroplasty.

Alignment outcomes and their impact on implant survival following unicompartmental knee arthroplasty (UKA) are unclear. The purpose of this study was to assess the implant survival and radiographic outcomes after UKA as well as the impact of component alignment and overhang on implant survival. We performed a retrospective analysis of 253 primary fixed-bearing and mobile-bearing medial UKAs from a single academic center. All UKAs were performed by 2 high-volume fellowship-trained arthroplasty surgeons. UKAs comprised <10% of their knee arthroplasty practices, with an average of 14.2 medial UKAs per surgeon per year. Implant survival was assessed. Femoral coronal (FCA), femoral sagittal (FSA), tibial coronal (TCA), and tibial sagittal (TSA) angles as well as implant overhang were radiographically measured. Outliers were defined for FCA (>±10° deviation from neutral), FSA (>15° of flexion), TCA (>±5° deviation from neutral), and TSA (>±5° deviation from 7°). "Far outliers" were an additional >±2° of deviation. Outliers for overhang were identified as >3 mm for anterior overhang, >2 mm for posterior overhang, and >2 mm for medial overhang. Among patients with a failed UKA, revision was performed at an average of 3.7 years (range, 0.03 to 8.7 years). The cumulative revision rate was 14.2%. Kaplan-Meier survival analysis demonstrated 5 and 10-year survival rates of 88.0% (95% confidence interval [CI] = 82.0% to 91.0%) and 70.0% (95% CI = 56.0% to 80.0%), respectively. Only 19.0% (48) of the UKAs met target alignment for all 4 alignment measures, and only 72.7% (184) met all 3 targets for overhang. Only 11.9% (30) fell within all alignment and overhang targets. The risk of implant failure was significantly impacted by outliers for FCA (failure rate = 15.4%, p = 0.036), FSA (16.2%, p = 0.028), TCA (17.9%, p = 0.020), and TSA (15.2%, p = 0.034) compared with implants with no alignment or overhang errors (0%); this was also true for far outliers (p < 0.05). Other risk factors for failure were posterior overhang (failure rate = 25.0%, p = 0.006) and medial overhang (38.2%, p < 0.001); anterior overhang was not a significant risk factor (10.0%, p = 0.090). The proportions of UKA revisions and alignment outliers were greater than expected, even among high-volume arthroplasty surgeons performing an average of 14.2 UKAs per year (just below the high-volume UKA threshold of 15). Alignment and overhang outliers were significant risk factors for implant failure. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.