Long-term survival and radiological results of the Duracon™ total knee arthroplasty

Bilateral simultaneous total knee arthroplasty with and without patellar resurfacing. A prospective single surgeon series with a minimum follow-up of 7 years

BACKGROUND

Total knee arthroplasty (TKA) is the most effective treatment for end-stage adult knee osteoarthritis, but it has been reported that patient satisfaction may vary. A malfunction of the patellofemoral joint may produce anterior knee pain (AKP) for several reasons. While some surgeons systematically resurface the patella despite the risk of potential complications such as fracture, loosening, or wear of the patella, others prefer to preserve it to reduce AKP and revision rates. This study aimed to evaluate whether patellar resurfacing had better clinical and functional outcomes, complications, and revision rates in patients undergoing simultaneous bilateral total knee arthroplasty.

METHODS

We conducted a prospective cohort study, including patients who underwent bilateral simultaneous TKA in which the patella was replaced in one knee and preserved in the other, with a minimum follow-up of 7 years. We assessed clinical and functional outcomes with the Knee Society Score (KSS) and Visual Analogue Scale (VAS); complications and revision rates were also registered.

RESULTS

The final series consisted of 43 patients with 86 knee arthroplasties. After a mean of 7.6 years of follow-up, no significant differences were found regarding KSS (clinical: 82.8 ± 7.4 versus 83.2 ± 3.4, p = 0.92; functional 89.1 ± 8.2: versus 90.4 ± 6.8; p = 0.99), VAS (2.0 ± 0.9 versus 1.8 ± 1.0; p = 0.84), complications (10.5% versus 8.1%; p = 0.57), or revision rates (2.3% versus 2.3%; p = 0.99) when comparing patellar resurfacing versus retention.

CONCLUSION

In the context of total knee arthroplasty, patellar replacement did not demonstrate statistically significant differences concerning patellar retention in clinical nor functional outcomes, AKP, complications, or revision rates after a minimum of 7 years of follow-up.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Twenty-year survivorship cohort study of total knee arthroplasty in Asian patient using a single posterior-stabilized implant performed by a single surgeon

INTRODUCTION

As life expectancy has improved, the potential number of revision candidates is also expected to increase among patients who have undergone a total knee arthroplasty (TKA). The longevity of modern posterior stabilized knee prostheses after 20 years of use has not been well documented, especially in Asian populations that require a deeper flexion range due to a floor-based lifestyle.

HYPOTHESIS

Firstly, the implant longevity regarding mechanical failures such as aseptic loosening and polyethylene (PE) wear would vary over a longer follow-up depending on the age groups; and secondly there would be unique risk factors for revision surgery in an Asian TKA cohort.

MATERIAL AND METHODS

We conducted this age-stratified survival analysis in a consecutive series of 368 NexGen Legacy Posterior Stabilized (LPS) TKAs performed by a single surgeon. These cases were divided into four age groups (< 60 years, early 60s, late 60s, and ≥ 70 years). The implant longevity against aseptic mechanical failures was calculated using the Kaplan-Meier method. The revision surgery risk was evaluated using postoperative factors including a deep flexion capability (> 135̊), and postoperative mechanical alignments.

RESULTS

Overall survivorship was significantly lower in the youngest groups than other groups (Log-rank test, p=0.001). The cumulative 20-year implant longevity was more than 95% in the two oldest groups, but less than 60% in the youngest group. It was notable that the post-TKA implant longevity was not apparent up to 10 years between the age groups (p=0.073∼0.458). Aseptic loosening was observed with an earlier onset (3.1 to 18.9 years) trend than PE wear (9.8∼17.9 years), with most cases arising in the youngest groups. Flexion limitation and varus alignment were significant risks to aseptic loosening and PE wear (Cox proportional hazard regression: p=0.001 and 0.045, respectively).

DISCUSSION

A younger age (< 60 years), inability of postoperative deep flexion, and varus alignment were significant risk factors for aseptic loosening and PE wear after modern PS design in this Asian cohort. The difference in postoperative longevity affected by these factors was not obvious during the first 10 years but emerged over a second decade.

LEVEL OF PROOF

III; retrospective cohort study.

No Correlation Between Clinical Outcomes and Changes in the Tibia-Metaphyseal Angle Following Total Knee Arthroplasty: A Retrospective Study

BACKGROUND

Despite numerous advances in the implant design and surgical technique, improvement in patient satisfaction following total knee arthroplasty (TKA) has plateaued. Various TKA alignment strategies have been introduced that impact the coronal positioning of the tibial component relative to the native joint line. This study aims to analyze if postoperative variance of the joint line from preoperative native alignment is correlated with changes in patient-reported outcomes following primary TKA.

METHODS

A retrospective review of an academic center's patient population identified all primary TKAs between 2013 and 2021 with full-length, standing radiographs and patient-reported outcome measures (PROMs) data. These measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement, Patient-Reported Outcome Measurement Information System, and Veterans RAND 12 scores. Preoperative and postoperative radiographic measurements for hip-knee angle, tibia-metaphyseal angle, tibial-axis orientation angle, and joint-line obliquity angle were recorded. Three-month, 1-year, and 2-year PROM scores were correlated with the change in degrees for each of the angles using a Spearman's correlation. A Mann-Whitney U-test was used to compare angular changes with a change in PROM scores.

RESULTS

One hundred and ninety nine patients (204 knees) with a mean age of 67 years were included. Average follow-up was 23 months. Three-month, 1-year, and 2-year follow-up rates were 93%, 64%, and 34%, respectively. Improvements were seen across all PROMs regardless of an angular change.

CONCLUSION

There were no clear correlations between PROMs and variation in joint line obliquity in the coronal plane. These data suggest that the magnitude of the variation in coronal tibial alignment from native alignment does not impact PROMs. Further study is indicated to correlate an angular change with functional measures.

The Impact of Psychological Health on Patient Recovery After Arthroplasty

PURPOSE

The purpose of this study was to determine the relationship between psychological health and postoperative recovery and satisfaction in patients undergoing total joint arthroplasty (TJA).

METHODS

We prospectively enrolled patients undergoing TJA from July 2019 to December 2020. A psychological evaluation was conducted according to the Hospital Anxiety and Depression Scale (HADS). Based on the preoperative HADS scores, we grouped the patients into two groups: the symptomatic group and the asymptomatic group. Data on the Harris Hip Score (HHS), Knee Society Knee Scoring System (KSS), Forgotten Joint Score-12 (FJS-12), Short Form-12 (SF-12), and Numeric Rating Scale (NRS) for pain in these two groups were collected preoperatively and postoperatively. Then, these data were analyzed by Statistical Package for Social Sciences (SPSS) version 19.

RESULTS

The final cohort consisted of 80 patients. Patients undergoing TJA had significantly decreased HADS and NRS scores and improved HHS, KSS, SF-12, and FJS-12 scores (all p < 0.001). Compared with the symptomatic group, the asymptomatic group showed better postoperative recovery (p < 0.05), especially after total knee arthroplasty (TKA) (p < 0.05). Good postoperative recovery positively impacted the patients' postoperative psychological state.

CONCLUSION

Finally, the psychological state can affect recovery after TJA, and successful TJA can help improve patients' psychological states, especially after TKA.

A Randomized Controlled Trial of Psychological Intervention to Improve Satisfaction for Patients with Depression Undergoing TKA: A 2-Year Follow-up

BACKGROUND

The overall satisfaction of patients after total knee arthroplasty (TKA) is approximately 80%, and current studies have demonstrated that patients with depression may have lower patient satisfaction. The purpose of this study was to determine whether perioperative psychological intervention in patients with depression improves the clinical outcomes and patient satisfaction in patients undergoing TKA.

METHODS

Six hundred patients who underwent primary TKA from May 2016 to January 2018 were prospectively screened for eligibility. A preoperative psychological evaluation was conducted by a psychiatrist to evaluate each patient's psychological status. Patients who were diagnosed with depression were randomly divided into 2 groups: the intervention group (patients received psychological interventions that were administered by a psychiatrist at the first visit before surgery and from then on) and the control group (patients received routine TKA care without psychological interventions). The primary outcome was patient satisfaction at 6 months postoperatively. The secondary outcomes were patient satisfaction at 2 years postoperatively as well as the Hospital for Special Surgery (HSS) scores, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and range of motion at 6 months and 2 years postoperatively.

RESULTS

Fifty-three patients with depression were identified. Fifty-one patients were enrolled in the randomized controlled trial. Two patients were lost to follow-up at 6 months after surgery. Therefore, 49 patients (25 in the intervention group and 24 in the control group) remained in the final analysis. At 6 months postoperatively, statistical differences in patient satisfaction were identified between the 2 groups (88.0% in the intervention group compared with 62.5% in the control group; odds ratio = 4.40; 95% confidence interval, 1.02 to 18.99). There was a significant improvement in the Self-Rating Depression Scale (SDS) score (the reduction rate was 51.97% in the intervention group compared with 17.35% in the control group) and the Symptom Checklist 90 Revised (SCL-90-R) subscore for depression (the reduction rate was 44.66% in the intervention group compared with 15.73% in the control group). The clinical outcomes, including the WOMAC scores, the HSS scores, and maximal range of motion, in the intervention group had improved significantly more compared with those in the control group.

CONCLUSIONS

Psychological interventions during the perioperative period can improve patient satisfaction in patients with depression who undergo TKA. Therefore, psychological intervention and management may be beneficial for patients with depression who are planning to undergo TKA.

LEVEL OF EVIDENCE

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

Current state of total knee arthroplasty

Total knee arthroplasty (TKA) is a successful and cost-effective treatment for end-stage degenerative arthritis. The aging of society and an increase in the prevalence of obesity has led to increases in the prevalence of arthritis and the incidence of TKA. Currently, the total number of procedures in Korea per year has reached 90,000. With the rapid growth, we need to know about the current state of TKA. The purpose of this review is to summarize the recent literature regarding TKA. The main indication for TKA is end-stage arthritis with severe pain, reduced function, and no response to conservative management. Metal on the polyethylene-bearing surface and cobalt alloy are used in most TKAs. Despite good clinical outcomes and long-term survival rates after TKA in many papers, 20% of patients are dissatisfied with the outcome of surgery. To improve the patient’s satisfaction, surgeons should understand factors affecting patient’s satisfaction, including patient’s expectations, age, and preoperative mental state. Navigation-assisted surgery and robotic surgery have been introduced in knee arthroplasty to achieve more precise and accurate alignment. There is some evidence to suggest that computer-assisted surgery reduces revision rates. However, clinical efficacy is also controversial, and a long-term follow-up study is required. The common complications of TKA include infection, polyethylene wear, loosening, stiffness, periprosthetic fracture, and thromboembolism. An understanding of the potential complications and pitfalls of TKA is essential for prevention.

Ten-Year Minimum Outcomes and Survivorship With a High Flexion Knee System

BACKGROUND

The purpose of this study is to report the long-term outcomes and survivorship of a high flexion knee system.

METHODS

We identified 1312 patients (1664 knees) who underwent primary total knee arthroplasty with the Vanguard Complete Knee System with 10-year minimum follow-up. Preoperative and postoperative range of motion, Knee Society scores, complications, and reoperations were evaluated.

RESULTS

At an average of 11.9 years of follow-up, 88 knees were revised (5.3%). The deep infection rate was 1.4%. There was an average range of motion improvement of 3.9°, pain level decreased by 35.8, Knee Society clinical scores improved by 48, and Knee Society functional scores improved by 15.1 (all P < .001). Survival was 96.4% at 10 years for aseptic causes and 95.5% for all causes.

CONCLUSION

At a 10-year minimum follow-up, this high flexion knee system demonstrates excellent survivorship.

Genesis 1 posterior cruciate-retaining total knee arthroplasty with asymmetric tibial tray: An 18-to-26-year long-term clinical outcome study

BACKGROUND

To present the long-term clinical and radiological outcomes of the Genesis I posterior cruciate-retaining total knee arthroplasty (TKA) (Smith & Nephew Orthopaedics, Memphis, TN, USA) (one of the first designed with an asymmetric tibial tray).

METHODS

Prospectively collected data from 117 cemented TKAs performed on 95 patients were evaluated using this design, with a mean follow-up of 21.5 years (range, 18-26). Failures, complication rates, and clinical (both subjective and objective) and radiological outcomes were assessed for all patients.

RESULTS

Seven failures occurred (wear and structural failure of the polyethylene insert) and six revision surgeries were performed at a mean of 10 years (range, three to 14) from the index operation. No revision of either the femoral or tibial components for aseptic loosening was performed. Survivorship analysis showed a cumulative success rate of 93.53% (95% CI, 92.75-94.32%) at 20 and 25 years, with revision for any reason as an end point. All patients showed a statistically significant improvement (P = 0.001) in the Knee Society and Oxford knee rating scores.

CONCLUSIONS

This study demonstrated satisfactory long-term clinical outcomes for this TKA design, with revisions being related to polyethylene wear structural failure.

Malalignment and malposition of quadriceps-sparing approach in primary total knee arthroplasty: a systematic review and meta-analysis

Background

Quadriceps-sparing (QS) approach is considered to be the most minimally invasive surgery for total knee arthroplasty (TKA). We perform this meta-analysis to evaluate whether malalignment and malposition are more biased towards the QS approach compared to the traditional medial parapatellar (MP) approach, which is still controversial.

Methods

According to the PRISMA guidelines, a comprehensive search was conducted in the databases of PubMed, the Cochrane library, and Embase. Relevant measures were extracted independently by two investigators.

Results

Five randomized controlled trials (RCTs) and eight retrospective studies including a total of 1261 cases were identified. The QS approach was associated with more outliers of hip-knee-ankle (HKA) angle (p = 0.03), coronal tibial component angle (p = 0.03), and femoral notch (p = 0.05). However, the differences of the outlier of the coronal femoral component angle between the two groups were not statistically significant.

Conclusions

This meta-analysis indicates that the QS approach is related to the high risk of malalignment and malposition. However, different studies reported different indicators resulting in small samples for analyzing the radiological outcomes. In addition, both of the relatively long learning curve and the present instruments might increase the risk of malalignment and malposition of the QS approach, which needs further study and improvement.

Do Medial Pivot Kinematics Correlate With Patient-Reported Outcomes After Total Knee Arthroplasty?

BACKGROUND

Many total knee arthroplasty (TKA) implants are designed to facilitate a medial pivot kinematic pattern. The purpose of this study was to determine whether intraoperative medial pivot kinematic patterns are associated with improved patient outcomes.

METHODS

A retrospective review of consecutive primary TKAs was performed. Sensor-embedded tibial trials determined kinematic patterns intraoperatively. The center of rotation (COR) was identified from 0° to 90° and from 0° to terminal flexion, and designated medial-pivot or non-medial pivot based on accepted criteria. Patient-reported outcomes were measured preoperatively and at minimum one-year follow-up.

RESULTS

The analysis cohort consisted of 141 TKAs. Mean age and median BMI were 63.7 years and 33.8 kg/m², respectively. Forty-percent of TKAs demonstrated a medial pivot kinematic pattern intraoperatively. A medial pivot pattern was more common with posterior cruciate-retaining (CR) and posterior cruciate-substituting/anterior lipped (CS) implants when compared to posterior stabilized (PS) TKAs (P ≤.0150). Regardless of bearing type, minimum one-year Knee Society scores and UCLA activity level did not significantly differ based on medial vs non-medial pivot patterns (P ≥.292). For patients with posterior cruciate-sacrificing implants, there were trends for greater median improvement in Knee Society objective (46 vs 31.5 points, P =.057) and satisfaction (23 vs 14 points, P =.067) scores in medial pivot knees.

CONCLUSION

A medial pivot pattern may not significantly govern clinical success after TKA based on intraoperative kinematics and modern outcome measures. Further research is warranted to determine if a particular kinematic pattern promotes optimal clinical outcomes.

Clinical Results and Survivorship of the GENESIS II Total Knee Arthroplasty at a Minimum of 15 Years

BACKGROUND

The purpose of this study was to examine the 15-year survivorship and long-term clinical outcomes of the GENESIS II total knee arthroplasty (TKA).

METHODS

Patients who underwent TKA with the GENESIS II system between 1995 and 1999 were retrieved from our institutional database. We report a Kaplan-Meier survival analysis as well as Western Ontario and McMaster Universities Arthritis Index, the Short Form Health Survey-12 (SF-12), and the Knee Society Scores at a mean of 16 years.

RESULTS

Four-hundred sixty-nine TKAs were performed with a mean patient age of 68 years. Patients were followed up prospectively for a mean of 16 years (range, 14.8-19.5 years). The Kaplan-Meier survival analysis at 15 years, with revision for any reason as the end point, was 96.4% (95.5%-97.3%). The Western Ontario and McMaster Universities Arthritis Index and the Knee Society Scores were significantly improved (P < .001) from the preoperative period to the latest follow-up. Patients had a significant improvement (P < .001) from the preoperative to the latest follow-up on the Physical Health Composite Score of the SF-12, but no change was noted on the Mental Health Composite Score of the SF-12.

CONCLUSION

The unique design features of the GENESIS II TKA system have remained a constant over the duration of its clinical use, a rarity for contemporary TKA systems which are often altered before the publication of long-term results. The GENESIS II continues to demonstrate excellent long-term survivorship and improvements in health-related outcomes at a mean of 15 years, representing the standard for TKA systems at our institution.

Unicompartmental knee arthroplasty in patients over 75 years: a definitive solution?

INTRODUCTION

The purpose of this study was to perform a mid-long-term clinical and radiographic evaluation of the results obtained in patients older than 75 years treated with minimally invasive unicompartmental knee arthroplasty (UKA). The hypothesis was that UKA is a viable solution for the definitive treatment of localized disease in this age group, with good results and a low failure rate.

METHODS

An all-poly tibial component UKA was applied with a minimally invasive technique. Sixty-seven knees in patients with a minimum age of 75 years were evaluated at mean 9 years' follow-up. The Oxford knee score, Knee Society Score, WOMAC score, Visual Analogue Scale (VAS) for pain self-assessment and range of motion (ROM) were determined, as well as weight-bearing antero-posterior and laterolateral radiographs.

RESULTS

All clinical scores, as well as VAS and ROM, improved significantly at 9-year follow-up, and the outcome was considered good or excellent in 92.6% of the patients. Radiographic results showed that both tibial plateau angle and posterior tibial slope angles were maintained, whereas femoro-tibial angle was significantly changed at follow-up. Further analysis showed no significant correlation between clinical scores and body mass index, whereas the clinical outcome was correlated with the ROM obtained. Only two failures and one major post-operative complication were observed.

CONCLUSIONS

UKA is a viable option for treating unicompartmental knee osteoarthritis. With the proper indications and an accurate technique UKA may be indicated also in very elderly patients with reduced complications and morbidity, and excellent survivorship.

Retrospective comparative study shows no significant difference in postural stability between cruciate-retaining (CR) and cruciate-substituting (PS) total knee implant systems

PURPOSE

Modified postural stability after retaining the posterior cruciate ligament (PCL) in total knee arthroplasty is still discussed controversially. The objective of this study was to evaluate whether a PCL-retaining implant design should be preferred over a PCL-substituting implant design regarding postural stability in one-leg stance and clinical outcome.

METHODS

Forty patients underwent total knee arthroplasty, 20 of them with a cruciate-retaining (CR) and 20 of them with a cruciate-substituting (PS) implant system. Postural stability was analysed 6 months postoperatively in one-leg stance using the Biodex Balance System. In addition, the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Knee Society Score were completed.

RESULTS

This study shows that there is no significant difference in postural stability between CR and PS) implant systems with PS implants showing better results in WOMAC score.

CONCLUSIONS

In case it is necessary to use a PS implant, no negative influence on postural stability is to be expected compared to a CR implant.

Long-Term Survivorship and Clinical Outcomes Following Total Knee Arthroplasty

Total knee arthroplasty (TKA) is one of the most successful commonly performed orthopedic procedures; as such, the purpose was to assess the long-term outcomes and survivorship of primary TKAs with a dual-radius prosthesis. We evaluated 125-patients (145-knees), with a mean age of 63 years (37-90 years) for a mean 11-year follow-up (10-13 years). Outcomes were assessed with KSS, UCLA, SF-36, satisfaction scores, and aseptic survivorship analysis. At 10-year follow-up, the UCLA (6-points), KSS objective (84-points) and functional (73-points), SF-36 physical (41-points) and mental (51-points), and patient satisfaction (14-points) scores were reported to be good to excellent. The 10-year Kaplan-Meier survivorship rate was 99%; one TKA demonstrated radiographic loosening. At a minimum 10-year follow-up, this device demonstrated satisfactory outcomes and outstanding aseptic-survivorship rates.

Radiographic Evaluations of Revision Total Knee Arthroplasty: A Plea for Uniform Assessments

Thorough radiographic evaluation is necessary for perioperative assessments in revision total knee arthroplasty. There has been a large degree of variability in reporting these findings within the peer-reviewed literature. Our purpose was to evaluate studies that radiographically assessed alignment in the coronal and sagittal plane, patella alignment and thickness, presence and characterization of implant interface, and radiolucency. Secondly, we reviewed studies using a standardized reporting system to evaluate radiographic findings (the Knee Society Roentgenographic Evaluation and Scoring System) and the number of times it was referenced. Only 62% of studies evaluated all radiographic parameters, 57% to 91% assessed each metric, and 55% used standardized reporting systems. This emphasizes the need for a uniform evaluation method to ensure consistent radiographic assessment and optimal standard of care.

Metal backed fixed-bearing unicondylar knee arthroplasties using minimal invasive surgery: a promising outcome analysis of 132 cases

BACKGROUND

Unicondylar knee arthroplasty (UKA) is a well-established treatment for isolated osteoarthritis (OA) of the medial knee compartment. Aim of this retrospective study was to evaluate the early clinical and radiological outcomes of a consecutive series of patients treated with medial metal backed fixed-bearing UKA. Furthermore, the influence of the component orientation on the outcome was analyzed.

METHODS

From 09/2006 to 11/2010 106 patients (132 knees; 69 ± 9 years) were treated using a metal backed fixed-bearing UKA with a MIS approach. All patients underwent a standardized clinical and radiological follow-up at 6 weeks, 1, 2 and 5 years. Mean follow-up was 3.4 ± 1.0 years. Two patients (three UKAs) deceased and two patients (two UKAs) were lost to follow-up. Three different survival analyses were performed using three different endpoints defining failure: (a) revision with exchange of any UKA component (b) aseptic loosening and (c), a worst case scenario, where it was assumed that all progressive radiolucencies would lead to aseptic loosening and thus these were additionally counted. Clinical outcome was assessed using the American knee society score (AKS) and the Oxford knee score (OKS). Radiographic analysis was done according to the American Knee Society Evaluation and Scoring System adapted for UKA and correlated with the AKS and OKS.

RESULTS

Five UKAs (3.8 %) were revised to total knee arthroplasties (TKAs) after a median of 25 (10-33) months. Five year survival was 95.2, 97.5 and 87.7% for the aforementioned endpoints. At final follow-up the median AKS knee score was 99 (50-100) points and the median AKS function score was 100 (60-100) points. The median OKS was 43 (8-48) points. Clinical outcome was independent of the component orientation.

CONCLUSION

Fixed-bearing UKA showed excellent clinical and radiological results at up to 5 years follow-up. Outcome was independent of component orientation.

Clinical and radiographic outcomes of an accelerometer-based system for the tibial resection in total knee arthroplasty

PURPOSE

The accelerometer-based system is a portable surgical navigation system for TKA that does not require the use of a large computer console for registration and alignment feedback as required in computer-assisted surgery (CAS). The purpose of this prospective study was to determine the accuracy of the accelerometer-based system in the tibial component positioning and also to evaluate clinical outcomes.

METHODS

Between December 2011 and July 2012, a total of 53 consecutive patients with primary gonarthrosis were prospectively enrolled for unilateral TKA using a handheld surgical navigation system to perform the tibial resection. Pre-operatively and postoperatively, patients were asked to fill out a visual analogue scale for pain (VAS) and a knee injury and osteoarthritis outcome score (KOOS). Standing antero-posterior (AP) hip-knee-ankle (HKA) and lateral knee-to-ankle radiographs were performed to determine the varus/valgus alignment and the posterior slope of the tibial components relative to the mechanical axis.

RESULTS

The mean duration of follow-up was 23 months. Average preoperative VAS was 8.3 ± 0.67, which significantly improved to a mean 1.2 ± 0.57 at final follow up (P < 0.001). All scores significantly increased compared with pre-operative scores, except for the KOOS sport component (P = 0.075) and quality of life (P = 0.19). Intra-operatively, the average reading provided by the system with regard to varus/valgus alignment before performing the tibial resection was 0.55° ± 0.43. The average postoperative radiographic alignment of the tibial component in the coronal plane was 0.65° ± 0.59 of deviation by the ideal alignment (P > 0.05).

CONCLUSION

This study demonstrates that the OrthAlign navigation system combines the accuracy of the computer-assisted surgery systems with the ease of use and familiarity of the traditional instruments while avoiding the drawbacks of the CAS technique and disadvantages of conventional IM femoral alignment systems. The system could demonstrate an improvement in the incidence of outliers in final coronal alignment, as compared with a patient-specific cutting guide.

Functional outcomes comparing Triathlon versus Duracon total knee arthroplasty: does the Triathlon outperform its predecessor?

PURPOSE

Total knee arthroplasty (TKA) prosthesis designs are constantly evolving to obtain greater functional performance. The aim of this study is to compare the functional outcomes between the newer single radius (SR) Triathlon prosthesis with its multiradius (MR) predecessor the Duracon.

METHOD

We analysed 1,012 primary TKA procedures which used either the Triathlon SR prosthesis or the Duracon MR prosthesis (338 Triathlon, 674 Duracon). Patients were assessed using the Knee Society score (KSS), range of movement measurements, pain and walking assessments at time points pre-operatively, one year and two years postoperatively.

RESULTS

Both groups were similar pre-operatively in terms of age, gender and body mass index (BMI). At one year postoperatively the Triathlon group had a significantly better flexion (P = 0.005) and KSS (function score P = 0.037, knee score P = 0.000). At two years postoperatively the Triathlons had maintained a significantly better KSS (function score P = 0.046, knee score P = 0.000) and also knee flexion (P = 0.02). Pain assessments at two years were significantly better in the Triathlon group (P = 0.002) with 66.3 % of patients experiencing no pain at that point compared to 54.4 % with Duracon knees.

CONCLUSION

This data supports the proposition that the use of Triathlon TKA results in improved outcomes for patients when compared to the Duracon TKA.