Implant design influences patient outcome after total knee arthroplasty: a prospective double-blind randomised controlled trial

Total knee arthroplasty using a cemented single-radius, condylar-stabilized design performed without posterior cruciate ligament sacrifice

Aims

Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice.

Methods

This retrospective cohort study included consecutive patients undergoing TKA at a specialist centre in the UK between November 2010 and December 2012. Data were collected using a bespoke electronic database and cross-referenced with national arthroplasty audit data, with variables including: preoperative characteristics, intraoperative factors, complications, and mortality status. Patient-reported outcome measures (PROMs) were collected by a specialist research team at ten years post-surgery. There were 536 TKAs, of which 308/536 (57.5%) were in female patients. The mean age was 69.0 years (95% CI 45.0 to 88.0), the mean BMI was 32.2 kg/m2 (95% CI 18.9 to 50.2), and 387/536 (72.2%) survived to ten years. There were four revisions (0.7%): two deep infections (requiring debridement and implant retention), one aseptic loosening, and one haemosiderosis.

Results

Kaplan-Meier analysis demonstrated no difference in implant survival according to sex, age, or obesity status. Ten-year PROMs were available for 196/387 (50.6%) surviving patients and were excellent: mean Oxford Knee Score 34.4 (95% CI 32.7 to 36.1); mean Forgotten Joint Score (FJS) 51.2 (95% CI 16.1 to 86.3); mean EuroQol five-dimension five-level questionnaire score 69.9 (95% CI 46.8 to 93.0); 141/196 (71.9%) achieved the 22-point FJS patient-acceptable symptom state (PASS); and 156/196 (79.6%) were "very satisfied or satisfied".

Conclusion

This is the only large study reporting ten-year implant survival and functional outcomes of TKA using a cemented single-radius design and with a CS tibial bearing construct. The findings of excellent implant survival, safety, and functional outcomes indicate that this combination is a safe and effective option in routine TKA. Further investigation of this single-radius design TKA with CS tibial bearings with well-matched patient study groups will allow further insight into the performance of these implants.

Ultracongruent Versus Posterior-Stabilized Polyethylene: No Difference in Anterior Knee Pain but Decreased Noise Generation

BACKGROUND

Noise generation and anterior knee pain can occur after primary total knee arthroplasty (TKA) and may affect patient satisfaction. Polyethylene design in cruciate-sacrificing implants could be a variable influencing these complications. The purpose of this study was to analyze the effect of polyethylene design on noise generation and anterior knee pain.

METHODS

We prospectively reviewed a cohort of patients who underwent primary TKA between 2014 and 2022 by a single surgeon using either a posterior-stabilized (PS) or ultracongruent (UC) polyethylene of the same implant design. The primary outcomes were measured through a noise generation questionnaire and the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score.

RESULTS

A total of 409 TKA procedures were included, 153 (37.4%) PS and 256 (62.6%) UC. No difference was noted in the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score between PS and UC designs (71.7 ± 26 versus 74.2 ± 23.2, P = 0.313). A higher percentage of patients in the PS cohort reported hearing (32.7% versus 22.3%, P = 0.020) or feeling noise (28.8 versus 20.3, P = 0.051) coming from their implant. No notable difference was observed in noise-related satisfaction rates. Independent risk factors of noise generation were age (OR, 0.96; P = 0.006) and PS polyethylene (OR, 1.61; P = 0.043). Noise generation was associated with decreased patient-reported outcome measure scores (P < 0.001).

CONCLUSION

While there was no difference in anterior knee pain between PS and UC polyethylene designs, PS inserts exhibit higher rates of noise generation compared with UC. Noise generation had comparable satisfaction but was associated with decreased patient-reported outcome measure scores.

Predicting 30-day unplanned hospital readmission after revision total knee arthroplasty: machine learning model analysis of a national patient cohort

Revision total knee arthroplasty (TKA) is associated with a higher risk of readmission than primary TKA. Identifying individual patients predisposed to readmission can facilitate proactive optimization and increase care efficiency. This study developed machine learning (ML) models to predict unplanned readmission following revision TKA using a national-scale patient dataset. A total of 17,443 revision TKA cases (2013-2020) were acquired from the ACS NSQIP database. Four ML models (artificial neural networks, random forest, histogram-based gradient boosting, and k-nearest neighbor) were developed on relevant patient variables to predict readmission following revision TKA. The length of stay, operation time, body mass index (BMI), and laboratory test results were the strongest predictors of readmission. Histogram-based gradient boosting was the best performer in distinguishing readmission (AUC: 0.95) and estimating the readmission probability for individual patients (calibration slope: 1.13; calibration intercept: -0.00; Brier score: 0.064). All models produced higher net benefit than the default strategies of treating all or no patients, supporting the clinical utility of the models. ML demonstrated excellent performance for the prediction of readmission following revision TKA. Optimization of important predictors highlighted by our model may decrease preventable hospital readmission following surgery, thereby leading to reduced financial burden and improved patient satisfaction.

Mid-term results of an anatomic total knee replacement design

INTRODUCTION

A significant proportion of patients remain dissatisfied following total knee arthroplasty (TKA) surgery. Reasons for this are unclear. Contemporary implants seek to mirror innate anatomy. Such innovations are necessarily subject to scrutiny to validate their use. The Zimmer-Biomet Persona® Personalized Knee system is such an anatomic TKA. This work seeks to establish medium term survival data and patient reported outcomes for this implant.

METHODS

This was a cohort study of prospectively collected data on all patients undergoing Persona TKA at our institution. Patients were managed using a standardised protocol for intra- and post-operative care. Survivorship data were collected using our National Joint Registry and corroborated with local data. Range of motion, Oxford Knee Score (OKS) and patient satisfaction were recorded at six weeks and one year post-operatively. Hip-knee-ankle radiographs were used to record pre- and post-operative alignment.

RESULTS

Data were collected for 749 knees in 679 patients. Overall survivorship was 99.0% at a mean 5.35 years, with seven patients undergoing revision surgery during the study period. Significant improvements in the OKS (mean 20.7 points) and range of motion were observed (mean 104.6° at one year). 94.9% of patients were satisfied at one year. Mean correction was to a mechanical femoro-tibial angle of 0.8° varus.

CONCLUSIONS

We demonstrate excellent medium term survival of the Persona TKA in this large cohort, coupled with improvements in patient reported outcomes, range of motion and patient satisfaction at one year which compare favourably to other implants.

Rehabilitation Techniques Before and After Total Knee Arthroplasty for a Better Quality of Life

The most important gold standard treatment following advanced knee osteoarthritis is total knee arthroplasty. Following surgery of total knee replacement, the majority of patients report decreased pain and successful long-term results, but recovery is unpredictable, and most patients continue to exhibit muscle weakness in their lower limbs and functional limitations in comparison to similarly aged control individuals. The goal of this review article was to systematically review different articles containing controlled and randomized studies to find out the effectiveness of outpatient care postoperatively on short- and long-term functional recovery. The purpose of this review article is to investigate the possible advantages of pre- and postoperative rehabilitation as well as the value of exercise regimen recommendations following total knee replacement. The following interventions after total knee arthroplasty are discussed in this review article: preoperative education and exercises, continuous passive movement, strengthening interventions, aquatic therapy, balanced training, tourniquet exposure, use of alignment and implants, role of apps in phones and different wearable devices, influence of postoperative protocols, knee bracing, neuromuscular electrical stimulation, and clinical environment. Strengthening and intense functional exercises for patients above 45 years of age, in land or water programs like aquatic activities, with the increasing intensity of the exercises in accordance with the patient's progress, should be included in the best outpatient physical therapy protocols. Because these exercises are so precisely personalized, the best long-term effects after surgery may come from outpatient physiotherapy performed in a clinical setting under the supervision of a registered physiotherapist or medical professional. This review article also includes the change in the quality and well-being of a patient's life who has undergone total knee arthroplasty and practiced the rehabilitation techniques.

Cost-utility analysis of robotic arm-assisted medial compartment knee arthroplasty

Aims

To perform an incremental cost-utility analysis and assess the impact of differential costs and case volume on the cost-effectiveness of robotic arm-assisted unicompartmental knee arthroplasty (rUKA) compared to manual (mUKA).

Methods

This was a five-year follow-up study of patients who were randomized to rUKA (n = 64) or mUKA (n = 65). Patients completed the EuroQol five-dimension questionnaire (EQ-5D) preoperatively, and at three months and one, two, and five years postoperatively, which was used to calculate quality-adjusted life years (QALYs) gained. Costs for the primary and additional surgery and healthcare costs were calculated.

Results

rUKA was associated with a relative 0.012 QALY gain at five years, which was associated with an incremental cost per QALY of £13,078 for a unit undertaking 400 cases per year. A cost per QALY of less than £20,000 was achieved when ≥ 300 cases were performed per year. However, on removal of the cost for a revision for presumed infection (mUKA group, n = 1) the cost per QALY was greater than £38,000, which was in part due to the increased intraoperative consumable costs associated with rUKA (£626 per patient). When the absolute cost difference (operative and revision costs) was less than £240, a cost per QALY of less than £20,000 was achieved. On removing the cost of the revision for infection, rUKA was cost-neutral when more than 900 cases per year were undertaken and when the consumable costs were zero.

Conclusion

rUKA was a cost-effective intervention with an incremental cost per QALY of £13,078 at five years, however when removing the revision for presumed infection, which was arguably a random event, this was no longer the case. The absolute cost difference had to be less than £240 to be cost-effective, which could be achieved by reducing the perioperative costs of rUKA or if there were increased revision costs associated with mUKA with longer follow-up.

Wider translations and rotations in posterior-stabilised mobile-bearing total knee arthroplasty compared to fixed-bearing both implanted with mechanical alignment: a dynamic RSA study

PURPOSE

The purpose of this study was to investigate the in vivo kinematics of the same femoral design mechanically aligned posterior-stabilised (PS) total knee arthroplasty (TKA) with either fixed-bearing (FB) or mobile-bearing (MB) inlay, implanted by the same surgeon, using model-based dynamic radiostereometric analysis (RSA). The hypothesis of the present study was that the MB design would show wider axial rotation than the FB design, without affecting the clinical outcomes.

MATERIALS AND METHODS

A cohort of 21 non-randomised patients (21 DePuy Attune PS-FB) was evaluated by dynamic RSA analysis at a minimum 9-month follow-up, while performing differently demanding daily living activities such as sit to stand (STS) and deep knee lunge (DKL). Kinematic data were compared with those of a cohort of 22 patients implanted with the same prosthetic design but with MB inlay. Anterior-posterior (AP) translations, varus-valgus (VV) and internal-external (IE) rotations of the femoral component with respect to the tibial baseplate were investigated. Translation of medial and lateral compartment was analysed using the low point method according to Freeman et al. Questionnaires to calculate objective and subjective clinical scores were administered preoperatively and during follow-up visit by the same investigator.

RESULTS

The FB TKA design showed lower AP translation during STS (6.8 ± 3.3 mm in FB vs 9.9 ± 3.7 mm in MB, p = 0.006*), lower VV rotation (1.9 ± 0.8° in FB vs 5.3 ± 3.3° in MB, p = 0.005) and lower IE rotation (2.8 ± 1.1° in FB vs 9.5 ± 4.3° in MB, p = 0.001) during DKL than the mobile-bearing TKA design. Posterior-stabilised FB group showed significant lower translation of the low point of the medial compartment than the MB group (p = 0.008). The percentage of patients performing medial pivot in the FB group was higher compared to MB group in the examined motor tasks. No significant differences in post-operative range of motion (117° ± 16° for FB group and 124° ± 13° for MB group) and in clinical outcomes emerged between the two cohort.

CONCLUSIONS

The FB and MB designs differed in AP translations, VV rotations and IE rotations of the femoral component with respect to the tibial component in STS and DKL. Furthermore, FB cohort reported a significant higher percentage of medial pivot with respect to MB cohort. Despite this, no differences in clinical outcomes were detected between groups. Both designs showed stable kinematics and represent a viable option in primary TKA.

LEVEL OF EVIDENCE

Prospective cohort study, II.

Cost-utility analysis of total knee arthroplasty using 10-year data from a randomised controlled trial: Implant design influences quality-adjusted life year gain

BACKGROUND

The aim of this study was to perform a cost-utility analysis for total knee arthroplasty (TKA) over a 10-year follow up period.

METHODS

Two-hundred and twelve patients were randomised to receive either a Kinemax or a Triathlon TKA. Patients were assessed pre-operatively, and at 6 months, and 1, 3, 7 and 10 years postoperatively. The costs of the primary and revision surgery were accounted for. One-year quality-adjusted life year (QALY) gain was used to estimate 10-year gains using the established annual health gain discounts.

RESULTS

Forty-eight patients died and eight were revised during the follow up period. Overall QALY gain per patient over the 10-year period was 2.594 and the cost per patient was £6559, which resulted in a cost per QALY of £2761 at 10 years. The Triathlon group had a significantly greater QALY gain compared with the Kinemax (mean difference (MD) 0.53, 95% CI 0.03-1.03, P = 0.02), which resulted in a cost per QALY for the Triathlon group of £2521 compared with £3107 for the Kinemax group at 10 years. The 5% annual discount resulted in a significantly lower QALY gain (MD 0.135, 95% CI 0.201-0.354, P = 0.002), whereas the 3.5% annual discount resulted in non-significant difference in QALY gain compared with the actual gain (MD 0.021, 95% CI -0.084 to 0.077, P = 0.292).

CONCLUSIONS

TKA was a cost-effective intervention, and the Triathlon was associated with a greater cost effectiveness at 10 years. The 3.5% annual discounts for QALY gain would seem to be the most accurate, with an underestimation being observed with the 5% discount.

Can Arthroplasty Stem Influence Outcome: A Randomized Controlled Trial of Stem Length in Cemented Total Hip Arthroplasty

BACKGROUND

The primary aim was to assess whether a short (125 millimeter (mm)) stem offered an equivalent hip-specific function compared to the standard (150 mm) stem when used for cemented total hip arthroplasty. Secondary aims were to evaluate health-related quality of life, patient satisfaction, stem height and alignment, as well as radiographic loosenings and complications between the two stems.

METHODS

A prospective twin-center double-blind randomized control trial was conducted. During a 15-month period, 220 patients undergoing total hip arthroplasty were randomized to either a standard (n = 110) or a short (n = 110) stem. There were no significant (P ≥ .065) differences in preoperative variables between the groups. Functional outcomes and radiographic assessment were undertaken at a mean of 1 and 2 years.

RESULTS

There were no differences (P = .428) in hip-specific function according to the mean Oxford hip scores at 1 year (primary endpoint) or at 2 years (P = .622) between the groups. The short stem group had greater varus angulation (0.9 degrees, P = .003) when compared to the standard group and were more likely (odds ratio 2.42, P = .002) to have varus stem alignment beyond one standard deviation from the mean. There were no significant (P ≥ .083) differences in the forgotten joint scores, EuroQol-5-Dimension, EuroQol-visual analogue scale, short form 12, patient satisfaction, complications, stem height, or radiolucent zones at 1 or 2 years between the groups.

CONCLUSION

The cemented short stem used in this study had equivalent hip-specific function, health-related quality of life, and patient satisfaction when compared to the standard stem at mean 2 years post operation. However, the short stem was associated with a greater rate of varus malalignment, which may influence future implant survival.

Excessive flexed position of the femoral component causes abnormal kinematics and joint contact/ ligament forces in total knee arthroplasty

Poor clinical outcomes are reported in excessive flexion of the femoral component in total knee arthroplasty (TKA), but their mechanisms have not yet been elucidated. This study aimed to investigate the biomechanical effect of flexion of the femoral component. Cruciate-substituting (CS) and posterior-stabilised (PS) TKA were reproduced in a computer simulation. The femoral component was then flexed from 0° to 10° with anterior reference, keeping the implant size and the extension gap. Knee kinematics, joint contact, and ligament forces were evaluated in deep-knee-bend activity. When the femoral component was flexed 10° in CS TKA, paradoxical anterior translation of the medial compartment was observed at mid-flexion. The PS implant was best stabilised with a 4° flexion model in mid-flexion range. The medial compartment contact force and the medial collateral ligament (MCL) force increased with the flexion of the implant. There were no remarkable changes in the patellofemoral contact force or quadriceps in either implant. In conclusions, excessive flexion of the femoral component yielded abnormal kinematics and contact/ligament forces. Avoiding excessive flexion and maintaining mild flexion of the femoral component would provide better kinematics and biomechanical effects in CS and PS TKA.

Comparison of short-time functional outcomes after TKA between Multigen Plus CR and Physica KR prostheses

BACKGROUND

Aim of this study was to compare functional results within 36 months following primary total knee arthroplasty (TKA) using a conventional prosthesis Multigen Plus CR and a new Physica KR implant. Our hypothesis was that the use of the Kinematics-Retaining design of an TKA implant leads to a significantly greater improvement in the active range of motion and better functional results (KSS 1, KSS 2 and WOMAC score) than the conventional CR implant at short-term follow-up.

MATERIALS AND METHODS

We retrospectively analysed data of 234 patients who underwent primary TKA at our hospital from April 2010 to August 2015 with the CR type of implant and from July 2014 to August 2015 with the KR implant due to advanced knee arthrosis of IIIrd and IVth grade of Kellgren-Lawrence classification, with no major ligamentous instability. Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) questionnaire, Knee Society Scores 1 (KSS 1) and 2 (KSS 2) and flexion (AROM) were recorded preoperatively and at 6, 12 and 36 months after surgery.

RESULTS

Our study showed a statistically significant difference in functional results at three years with better KSS 1 score, a tendency to higher values in the KSS 2 score, as well as a statistically significant overall improvement in AROM in favour of the new KR design over the conventional CR implant with a post-hoc power analysis of 83.8%. We found that there was no statistically significant difference between groups when comparing WOMAC score and complications at short-term follow-up.

CONCLUSIONS

Our study provided more favourable clinical results for using Kinematics-Retaining implant in primary TKA. Further studies should focus on radiological and functional outcomes from mid- to long-term follow-up.

The Impact of Surgeon Variability on Patient-Reported Outcome Measures, Length of Stay, Discharge Disposition, and 90-Day Readmission in TKA

BACKGROUND

Studies involving total knee arthroplasty (TKA) have focused on patient-related factors as drivers of outcomes. Although some studies have investigated surgeon and/or surgery-level factors (i.e., approach, volume), the measure of variance in postoperative outcomes across surgeons following TKA has not been determined. The aim of the current study was to evaluate the relationship between the surgeon and 1-year patient-reported outcome measures, the length of stay, the discharge disposition, and 90-day readmission after TKA, as well as the differences in these variables among surgeons.

METHODS

Data were prospectively collected for 5,429 patients who underwent TKA at a large health-care system with 36 surgeons between 2016 and 2018. Likelihood ratio tests were performed to investigate the relationship between surgeon and the 1-year Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain subscale, KOOS-Physical Function Shortform (KOOS-PS), KOOS for Joint Replacement (KOOS-JR), patient acceptable symptom state (PASS), length of stay, discharge disposition, and 90-day readmission. The minimal clinically important difference (MCID) was used to assess meaningful outcomes. Variable importance was determined by the Akaike information criterion (AIC) increase, using ordinal and binary-response mixed-effect models.

RESULTS

There was a significant association between surgeon and KOOS-Pain (p < 0.001), KOOS-PS (p = 0.001), KOOS-JR (p < 0.001), PASS (p = 0.024), length of stay (p < 0.001), discharge disposition (p < 0.001), and 90-day readmission (p < 0.001). When modeling 1-year KOOS-Pain (AIC increase, 15.6), KOOS-PS (AIC increase, 6.8), KOOS-JR (AIC increase, 13.5), PASS (AIC increase, 1.9), length of stay, and discharge disposition, the surgeon variable contributed more to the 1-year outcome than some patient-level factors (e.g., body mass index, Charlson Comorbidity Index). The difference between the highest and lowest median probabilities of attaining the same value for the KOOS-Pain (11.2%), KOOS-PS (9.4%), KOOS-JR (11.8%), PASS (5.9%), length of stay (46.6%), discharge disposition (22.8%), and readmission (13.1%) indicated surgeon-level variability.

CONCLUSIONS

Surgeon-related factors may be stronger contributors to the 1-year patient-reported outcome measures and length of stay than patient characteristics emphasized in the literature. Current findings have suggested variability in patient-reported outcome measures, length of stay, discharge location, and 90-day readmission among surgeons. Surgeon variability should be considered when model-fitting in the setting of TKA.

LEVEL OF EVIDENCE

Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Kinematic function of knee implant designs across a range of daily activities

The aim of this randomized controlled trial was to measure and compare six-degree-of-freedom (6-DOF) knee joint motion of three total knee arthroplasty (TKA) implant designs across a range of daily activities. Seventy-five TKA patients were recruited to this study and randomly assigned a posterior-stabilized (PS), cruciate-retaining (CR), or medial-stabilized (MS) implant. Six months after surgery, patients performed five activities of daily living: level walking, step-up, step-down, sit-to-stand, and stand-to-sit. Mobile biplane X-ray imaging was used to measure 6-DOF knee kinematics and the center of rotation of the knee in the transverse plane for each activity. Mean 6-DOF knee kinematics were consistently similar for PS and CR, whereas MS was more externally rotated and abducted, and lateral shift was lower across all activities. Peak-to-peak anterior drawer for MS was also significantly lower during walking, step-up, and step-down (p < 0.017). The center of rotation of the knee in the transverse plane was located on the medial side for MS, whereas PS and CR rotated about the lateral compartment or close to the tibial origin. The kinematic function of MS was more similar to that of the healthy knee than PS and CR based on reduced paradoxical anterior translation at low flexion angles and a transverse center of rotation located in the medial compartment. Overall, 6-DOF knee joint motion for PS and CR were similar across all daily activities, whereas that measured for MS was appreciably different. The kinematic patterns observed for MS reflects a highly conforming medial articulation in the MS design.

Comparison of Single-Radius with Multiple-Radius Femur in Total Knee Arthroplasty: A Meta-Analysis of Prospective Randomized Controlled Trials

BACKGROUND

Whether there was clinical superiority for the single-radius prosthesis over the multi-radius prothesis in total knee arthroplasty (TKA) still remains to be clarified. We updated a meta-analysis including prospective randomized controlled trials (RCTs) to compare the clinical prognosis of patients receiving single-radius TKA (SR-TKA) or multi-radius TKA (MR-TKA).

METHODS

We searched the databases of PubMed, Web of Science, EMBASE, Cochrane Library, MEDLINE for eligible RCTs. Two reviewers evaluated the study quality according to the Risk of Bias tool of the Cochrane Library and extracted the data in studies individually. The extracted data included the baseline data and clinical outcome. The baseline data include the author's name, country, and year of included studies, the name of knee prosthesis used in studies, sample size, follow-up time, and BMI of patients. The clinical data comprised primary indicators including postoperative knee range of motion (ROM), sit-to-stand rest, severe postoperative scorings, such as visual analog scale (VAS), American Knee Society knee score (AKS), Oxford knee scoring (OKS), and SF-36 Quality of Life Scale, as well as various secondary indicators of complications including anterior knee pain, postoperative infection, aseptic prosthesis loosening, and prosthesis revision. The data analysis was performed using Review Manager 5.3 software and STATA 12.0. The sensitivity analysis was performed using STATA 12.0.

RESULTS

A total of 13 RCTs, along with 1720 patients and 1726 knees, were finally included in our present meta-analysis. We found that patients in SR-TKA group performed better in the sit-to-stand test (OR = 1.89, 95% CI: 1.05-3.41, p = 0.03) and satisfaction evaluation (OR = 3.27, 95% CI: 1.42-7.53, p = 0.005), which were only evaluated in two included RCTs. While no significant difference was found between SR-TKA and MR-TKA groups in terms of postoperative ROM, VAS scoring, AKS scoring, SF-36 scoring, OKS scoring, and various complications including anterior knee pain, postoperative infection, aseptic prosthesis loosening, and prosthesis revision.

CONCLUSION

In conclusion, our present meta-analysis indicated that SR implants were noninferior to MR implants in TKA, and SR implants could be an alternative choice over MR implants, since patients after SR-TKA felt more satisfied and performed better in the sit-to-stand test, with no significant difference in complications between SR-TKA and MR-TKA groups. While more relevant clinical trials with long-term follow-up time and specific tests evaluating the function of knee extension mechanism should be carried out to further investigate the clinical performance of SR implants.

Minimum 5-Year Outcomes of a Multicenter, Prospective, Randomized Control Trial Assessing Clinical and Radiological Outcomes of Patient-Specific Instrumentation in Total Knee Arthroplasty

BACKGROUND

Patient-specific instrumentation (PSI) was developed to produce more accurate alignment of components and consequently improve clinical outcomes when used in total knee arthroplasty. We compare radiological accuracy and clinical outcomes at a minimum of 5-year follow-up between patients randomized to undergo total knee arthroplasty performed using PSI or traditional cutting block techniques.

METHODS

This multicenter, randomized control trial included patients blinded to the technique 1used. Outcome measures were coronal alignment measured radiologically, Euroqol-5D, Oxford knee score, and International Knee Society Score measured at 1- and 5-year follow-up.

RESULTS

At a minimum 5-year follow-up, there were 38 knees in the PSI group and 39 in the conventional instrumentation group for analysis. Baseline demographics and clinical outcome scores were matched between groups. Overall, there was no significant difference in the coronal femoral angle (P = .59), coronal tibial angle (P = .37), tibiofemoral angle (P = .99), sagittal femoral angle (P = .34), or the posterior tibia slope (P = .12) between knees implanted using PSI and those implanted with traditional cutting blocks. On the measurement of coronal alignment, intraobserver reliability tests demonstrated substantial agreement (k = 0.64). Clinical outcomes at both 1-year and 5-year follow-up demonstrated statistically significant and clinically relevant improvement in scores from baseline in both groups, but no difference could be detected between the Euroqol-5D (P = .78), Oxford knee score (P = .24), or International Knee Society Score (P = .86) between the 2 groups.

CONCLUSION

This study has shown no additional benefit to PSI in terms of improved alignment or functional outcomes at minimum 5-year follow-up over traditional techniques.

Comparison between Mid-Term Results of Total Knee Arthroplasty with Single-Radius versus Multiple-Radii Posterior-Stabilized Prostheses

Single-radius (SR) prostheses and multiple-radii (MR) prostheses have different theoretical advantages; however, few comparative studies have been reported. The aim of the study was to compare mid-term clinical, radiological, and survival outcomes of SR and MR posterior-stabilized prostheses in total knee arthroplasty (TKA). Two hundred consecutive patients who underwent TKA between January 2012 and July 2013 were enrolled in the SR group (100 patients) and an MR group (100 patients), with a minimum follow-up of 5 years. Functional, radiological, satisfaction, and survival rates were evaluated. There was a significantly higher range of motion (ROM) in the SR group than in the MR group (flexion, 123.65 ± 10.12 degrees vs. 115.52 ± 10.03 degrees, p < 0.001). Quadriceps strength (3.05 ± 0.43 vs. 2.68 ± 0.58 kg, p = 0.025) and chair test results (80 [93.02%] vs. 69 [83.13%], p = 0.027) were better in the SR group than in the MR group. The SR group also had significantly less anterior knee pain (6 [6.98%] vs. 15 [18.07%], p < 0.05) and a better satisfaction rate than those in the MR group. No significant differences were observed in clinical scale scores such as Hospital for Special Surgery (HSS), Knee Society Score (KSS), and Short-Form 12 (SF-12), radiological results in terms of component position and radiolucent lines. The Kaplan-Meier survival curve estimates at 5 years were not significantly different (96.91% [95% confidence interval [CI]: 93.5-99.5%] vs. 94.86% [95% CI: 90.6-98.6%], p = 0.4696). The SR prosthesis design was better than that of the MR in terms of ROM, reduced anterior knee pain, contributions to better recovery of the extension mechanism, and higher satisfaction rates. The SR had similar results in clinical scales such as HSS, KSS, SF-12, radiological, or survival results to MR prostheses. More accurate measurements and longer-term follow-up are required.

Smart sensor implant technology in total knee arthroplasty

Innovations in computer technology and implant design have paved the way for the development of smart instruments and intelligent implants in trauma and orthopaedics to improve patient-related functional outcomes. Sensor technology uses embedded devices that detect physical, chemical and biological signals and provide a way for these signals to be measured and recorded. Sensor technology applications have been introduced in various fields of medicine in the diagnosis, treatment and monitoring of diseases. Intelligent 'Smart' implants are devices that can provide diagnostic capabilities along with therapeutic benefits. In trauma and orthopaedics, applications of sensors is increasing because of the advances in microchip technologies for implant devices and research designs. It offers real-time monitoring from the signals transmitted by the embedded sensors and thus provides early management solutions. Smart orthopaedic implants have applications in total knee arthroplasty, hip arthroplasty, spine surgery, fracture healing, early detection of infection and implant loosening. Here we have explored the role of Smart sensor implant technology in total knee arthroplasty. Smart sensor assisted can be used intraoperatively to provide objective assessment of ligament and soft tissue balancing whilst maintaining the sagittal and coronal alignment to achieve desired kinematic targets following total knee arthroplasty. It can also provide post-implantation data to monitor implant performance in natural conditions and patient's clinical recovery during rehabilitation. The use of Smart Sensor implant technology in total knee arthroplasty appears to provide superior patient satisfaction rates and improved functional outcomes.

Early Postoperative Pain After Total Knee Arthroplasty Is Associated With Subsequent Poorer Functional Outcomes and Lower Satisfaction

BACKGROUND

There are few studies investigating the effects of acute postoperative pain on functional outcomes after total knee arthroplasty (TKA). The aims of this study are to identify perioperative factors associated with increased early postoperative pain and investigate the effects of acute postoperative day 1 and 2 pain on outcomes at 6 months and 2 years post-TKA.

METHODS

1041 unilateral TKA patients were included in this retrospective cohort study. Patients were categorized into minor (visual analog scale: VAS <5) and major (VAS ≥5) pain groups based on postoperative day 1/2 VAS scores. Patients were assessed preoperatively, at 6 months and 2 years using Knee Society Knee Score and Function Scores (KSFS), Oxford Knee Score (OKS), SF-36 physical and mental component score (SF-36 PCS), expectation and satisfaction scores. Perioperative variables including age, gender, race, body mass index, American Society of Anesthesiologist status, type of anesthesia, and presence of caregiver were analyzed as predictors of postoperative acute pain. Wilcoxon two-sample test was used to analyze outcomes significantly associated with "major pain." Multiple logistic regression was used to identify predictors of "major pain."

RESULTS

Patients with "minor pain" had significantly better KSFS, Knee Society Knee Score, OKS, and SF-36 PCS scores at 6 months and significantly better KSFS, OKS, SF-36 PCS, and satisfaction at 2 years (P < .05). A significantly higher percentage of patients with "minor pain" met the minimal clinically important difference for SF-36 PCS at 6 months and KSFS at 2 years (P < .05). Women, Indian/Malay race, higher BMI, and use of general over regional anesthesia were independent predictors of getting "major pain" (P < .05).

CONCLUSION

Patients should be counseled about risk factors of postoperative pain to manage preoperative expectations of surgery. Patients should be managed adequately using multimodal pain protocols to improve subsequent functional outcomes while avoiding unnecessary opioid use.

Ten-Year Results of the Triathlon Knee Replacement: A Cohort Study

Introduction Studies evaluating the outcomes of different brands of knee prostheses are important to monitor patient outcomes and generate evidence to aid decisions around the choice of implant. The Triathlon® prosthesis (Stryker, Limerick, Ireland), one of the most commonly used total condylar knee prosthesis, is designed to provide greater knee motion and the potential for longer implant survivorship. The aim of this cohort study was to evaluate outcomes and survivorship of the Triathlon total knee replacement (TKR) up to 10 years post-operative. Methods Two-hundred sixty-six (266) patients listed for a Triathlon TKR in one orthopaedic hospital were recruited. Assessments were conducted preoperatively and then at three months and one, two, three, five, seven, and 10 years after surgery. Outcomes assessed included pain, function, knee-related quality of life (QoL), satisfaction, kneeling ability, activity levels, American Knee Society Score, complications, and survivorship. Results Large improvements in patient-reported outcomes were observed in the first three months after surgery, followed by small improvement up to one year post-operative, and then outcomes plateaued up to 10 years post-operative. Satisfaction with overall outcome ranged from 79%-94% over the duration of follow-up. Activity levels and kneeling ability were similar before and after surgery. There was a large improvement in the median American Knee Society score in the first three months post-operative, followed by a small but gradual improvement to 10 years post-operative. Survivorship was 95.4% (95% confidence interval 91.8-97.5%) at 10 years post-operative. Conclusions This study found that the Triathlon TKR results in excellent outcomes and survivorship to 10 years post-operative.

Biomechanical Consequences of Tibial Insert Thickness after Total Knee Arthroplasty: A Musculoskeletal Simulation Study

The thickness of the tibial polyethylene (PE) insert is a critical parameter to ensure optimal soft-tissue balancing in the intraoperative decision-making procedure of total knee arthroplasty (TKA). However, there is a paucity of information about the kinetic response to PE insert thickness variations in the tibiofemoral (TF) joint, and subsequently, the secondary effects on the patellofemoral (PF) biomechanics. Therefore, the purpose of this study was to investigate the influence of varying PE insert thickness on the ligament and TF compressive forces, as well as on the PF forces and kinematics, after a cruciate-retaining TKA. A previous patient-specific musculoskeletal model of TKA was adapted to simulate a chair-rising motion in which PE insert thickness was varied with 2 mm increments or decrements compared to the reference case (9 mm), from 5 mm up to 13 mm. Greater PE insert thickness resulted in higher ligament forces and concurrently increased the TF compressive force by 21% (13 mm), but slightly unloaded the PF joint with 7% (13 mm) while shifting the patella distally in the trochlear groove, compared to the reference case. Thinner PE inserts showed an opposite trend. Our findings suggest that the optimal PE insert thickness selection is a trade-off between the kinetic outcomes of the TF and PF joints.

Better quadriceps and hamstring strength is achieved after Total knee Arthroplasty with single radius femoral prostheses: a retrospective study based on isokinetic and isometric data

Background

Strength deficits, muscle imbalances, and quadriceps inhibition are common after the total knee arthroplasty (TKA). It was suggested that theoretically single radius (SR) femoral protheses could provide longer extensor moment arm compared to the multiple radius (MR) design. However, quantitative evidence has not yet been reported. Thus, the aim of the study was to investigate the differences in isokinetic data and to compare the patient-reported outcome scores between TKA SR and MR design.

Method

The present retrospective study included 36 TKA involving 16 knees (9 patients) using SR design implant and 20 knees (11 patients) using MR design implant. The mean follow-up time was longer than 1 year. Isokinetic knee flexion and extension torques of the operated leg were evaluated at 60°/s and 180°/s. Quadriceps and hamstring torques and ratios, work and power were recorded. Angle-specific torques were also collected at different extension or flexion angles.

Results

Both groups showed improvement in knee society scores (KSS) and knee injury, and osteoarthritis outcome score (KOOS) after operation. Patients in SR group had significantly higher scores in KSS-knee, symptoms and activities of daily living KOOS sub-score than those in the MR group at the end of the follow-up. The peak knee flexion torque, peak knee extension torque and maximum knee flexion work were greater in SR group at 180°/s and 60°/s. At 60°/s, and SR group had higher average knee flexion power and average knee extension power than MR group. In the isometric contraction test, the knee extension torque was higher in SR group than in MR group. At 180°/s, SR group showed higher flexion torques at 30°, 40°, 50°, 60° compared with MR group. At 60°/s, SR group showed higher flexion torques at 30°, 40°, 50°, 60°, 80° when compared with MR group. Additionally, SR group also provided higher extension torques at 40°, 50°, 60° than the MR group. There were no differences in other isokinetic and isometric parameters between the two groups.

Conclusion

Femoral design exerted an influence on quadriceps and hamstring strength after TKA, and SR design shows advantages, in terms of higher extension and flexion strength, over MR design.

Comparison of functional outcomes between single-radius and multi-radius femoral components in primary total knee arthroplasty: a meta-analysis of randomized controlled trials

PURPOSE

Our purpose in the current meta-analysis was to compare the functional outcomes in patients who have received single-radius (SR) or multi-radius (MR) femoral components in randomized controlled trials (RCTs) for primary total knee arthroplasty (TKA). The hypothesis was that there would be no statistically significant difference between two groups in terms of functional outcomes.

MATERIALS AND METHODS

We searched the international electronic databases PubMed, Embase, and the Cochrane Central Register of Controlled Trials up to February 2020 for RCTs that compared functional outcomes of SR and MR femoral component designs after primary TKA. We performed a meta-analysis of nine RCTs using the Knee Society Score for the knee (KSS-knee), KSS-function, Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), degree of knee flexion, extension, and complications, including postoperative infection and revision surgery.

RESULTS

The meta-analysis revealed no statistically significant differences in all the analyzed variables, including KSS-knee, KSS-function, KOOS, OKS, knee flexion, and knee extension. For postoperative complications, no statistically significant differences were detected for femoral component designs in postoperative infection or incidence of revision surgery between the two groups.

CONCLUSIONS

The current meta-analysis of RCTs did not show any statistically significant differences between SR and MR femoral component designs in terms of postoperative functional outcomes. Evaluated outcomes included functional outcome scores, degree of knee flexion, extension, and complications. However, because of the limited clinical evidence of this study owing to the heterogeneity between the included RCTs, a careful approach should be made in order not to arrive at definite conclusions.

Comparison of Knee Kinematics and Kinetics during Stair Descent in Single- and Multi-Radius Total Knee Arthroplasty

Despite continuing advances, nearly 20% of patients remain dissatisfied with their total knee arthroplasty (TKA) outcomes. Single-radius (SR) and multiradius (MR) TKA designs are two commonly used knee replacement designs based on competing theories of the flexion/extension axis of the knee. Our aim was to characterize stair descent kinematics and kinetics in SR and MR TKA subjects. We hypothesized that 1 year after TKA, patients who received SR TKA will more closely replicate the knee kinematics and kinetics of healthy age-matched controls during stair descent, than will MR TKA patients. SR subjects (n = 12), MR subjects (n = 12), and age-matched controls (n = 12) descended four stairs affixed to force platforms, while 10 infrared cameras tracked markers attached to the body to collect kinematic and kinetic data. Both patient groups had improvements in stair descent kinetics and kinematics at the 1-year postoperative time point. However, SR TKA subjects were indistinguishable statistically from age-matched controls, while MR TKA subjects retained many differences from controls. Similar to previous reports for level walking, the SR knee design performs closer to healthy controls than MR knees during stair descent. This study demonstrates that patients who receive SR TKA have more improved kinematic normalization during stair descent postoperatively than those who received an MR TKA.

Comparison of intraoperative kinematics and their influence on the clinical outcomes between posterior stabilized total knee arthroplasty and bi-cruciate stabilized total knee arthroplasty

BACKGROUND

Of all the intraoperative kinematic parameters recorded using navigation systems, femorotibial rotational alignment is reportedly associated with the clinical outcomes of cruciate retaining and posterior stabilized (PS) total knee arthroplasty (TKA). However, to our knowledge, there are no reports on the relationship of newly designed bi-cruciate stabilized (BCS) TKA and intraoperative rotational kinematics. We aimed to clarify and compare the relationships between the intraoperative kinematics and clinical outcomes of BCS TKA and PS TKA.

METHODS

We compared the intraoperative rotational kinematics and clinical outcomes at two years postoperatively of 56 BCS TKA patients and 55 PS TKA patients. Further, we evaluated the relationship between the femorotibial rotational kinematics and clinical outcomes.

RESULTS

The maximum flexion angle and the pain subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS) in BCS TKA were significantly better than those in PS TKA. The intraoperative kinematic data of BCS TKA showed "screw-home" movement, while that of PS TKA did not show this movement. The rotational angular differences between at maximum flexion angle and at 60° flexion of BCS TKA showed positive correlations with the improvement of KOOS pain, symptom, activity of daily living and sports subscales. The rotational angular differences between at maximum flexion angle and at 30° flexion in PS TKA showed positive correlations with the maximum flexion angle.

CONCLUSION

Intraoperative femorotibial rotational kinematics and its influence on the clinical outcomes were different between BCS and PS TKA. BCS TKA showed more normal-like kinematics and better clinical results than PS TKA.

Factors affecting aseptic loosening in primary total knee replacements: an in vitro study

Background

Implant surface integrity and cement bonding are assumed to be sufficient in primary total knee replacements to stabilize implants for extended wear without concerns over delamination and loosening. Yet there exists a significant rate of aseptic loosening where failure at implant cement interface occurs. The aim of this study is to look at specific aspects leading to aseptic loosening of the total knee replacement, where cement adhesion to the implant results in the lowest pull off strength.

Methods

Virgin ceramic coated and uncoated chrome cobalt tibial trays were used in a pull off study using differing viscosities of cement at varied time intervals to compare which combination is strongest compared to which is least resistant to pull off testing.

Results

Low viscosity cement had a 44% (5.9 kg verses 3.3 kg, p < 0.001) higher pull-off strength compared to high viscosity cement. Coated implants had a 30% (3.9 kg verses 5.5 kg, p = 0.037) lower pull-off strength compared to non-coated. Testing measures were limited to cement utilization less than 5 minutes due to the poor adhesion of the dowels beyond this time. Finally, there was a significant difference in adhesion properties between brand names when utilizing low viscosity cement on the non-coated trays (10.34 kg for Simplex verses 4.87 for Palacos, p = 0.021).

Conclusion

There are differences in adhesion properties between cement vendors, prompting significant concerns over the use of coated implants with particular cement types. Use of low viscosity cement on non-coated surfaces in the early liquid phase of cement curing was found to produce the best chance for adequate adhesion. This study demonstrates that there is variation in the adhesive properties of implants utilized in total knee replacements, and that the orthopedic community should consider not only the implant, cement, and curing time individually, but the overall integrity conferred from the combination of all of these variables.

Reduction in patient outcomes but implant-derived preservation of function following total knee arthroplasty: longitudinal follow-up of a randomized controlled trial

AIMS

There are comparatively few randomized studies evaluating knee arthroplasty prostheses, and fewer still that report longer-term functional outcomes. The aim of this study was to evaluate mid-term outcomes of an existing implant trial cohort to document changing patient function over time following total knee arthroplasty using longitudinal analytical techniques and to determine whether implant design chosen at time of surgery influenced these outcomes.

METHODS

A mid-term follow-up of the remaining 125 patients from a randomized cohort of total knee arthroplasty patients (initially comprising 212 recruited patients), comparing modern (Triathlon) and traditional (Kinemax) prostheses was undertaken. Functional outcomes were assessed with the Oxford Knee Score (OKS), knee range of movement, pain numerical rating scales, lower limb power output, timed functional assessment battery, and satisfaction survey. Data were linked to earlier assessment timepoints, and analyzed by repeated measures analysis of variance (ANOVA) mixed models, incorporating longitudinal change over all assessment timepoints.

RESULTS

The mean follow-up of the 125 patients was 8.12 years (7.3 to 9.4). There was a reduction in all assessment parameters relative to earlier assessments. Longitudinal models highlight changes over time in all parameters and demonstrate large effect sizes. Significant between-group differences were seen in measures of knee flexion (medium-effect size), lower limb power output (large-effect size), and report of worst daily pain experienced (large-effect size) favouring the Triathlon group. No longitudinal between-group differences were observed in mean OKS, average daily pain report, or timed performance test. Satisfaction with outcome in surviving patients at eight years was 90.5% (57/63) in the Triathlon group and 82.8% (48/58) in the Kinemax group, with no statistical difference between groups (p = 0.321).

CONCLUSION

At a mean 8.12 years, this mid-term follow-up of a randomized controlled trial cohort highlights a general reduction in measures of patient function with patient age and follow-up duration, and a comparative preservation of function based on implant received at time of surgery. Cite this article: Bone Joint J 2020;102-B(4):434-441.

Kneeling ability after total knee replacement

Kneeling ability is consistently the poorest patient-rated outcome after total knee replacement (TKR), with 60-80% of patients reporting difficulty kneeling or an inability to kneel.Difficulty kneeling impacts on many activities and areas of life, including activities of daily living, self-care, leisure and social activities, religious activities, employment and getting up after a fall. Given the wide range of activities that involve kneeling, and the expectation that this will be improved with surgery, problems kneeling after TKR are a source of dissatisfaction and disappointment for many patients.Research has found that there is no association between range of motion and self-reported kneeling ability. More research is needed to understand if and how surgical factors contribute to difficulty kneeling after TKR.Discrepancies between patients' self-reported ability to kneel and observed ability suggests that patients can kneel but elect not to. Reasons for this are multifactorial, including knee pain/discomfort, numbness, fear of harming the prosthesis, co-morbidities and recommendations from health professionals. There is currently no evidence that there is any clinical reason why patients should not kneel on their replaced knee, and reasons for not kneeling could be addressed through education and rehabilitation.There has been little research to evaluate the provision of healthcare services and interventions for patients who find kneeling problematic after TKR. Increased clinical awareness of this poor outcome and research to inform the provision of services is needed to improve patient care and allow patients to return to this important activity. Cite this article: EFORT Open Rev 2019;4:460-467. DOI: 10.1302/2058-5241.4.180085.

Comparison of patient-reported outcomes based on implant brand in total knee arthroplasty

Aims

The outcomes of total knee arthroplasty (TKA) depend on many factors. The impact of implant design on patient-reported outcomes is unknown. Our goal was to evaluate the patient-reported outcomes and satisfaction after primary TKA in patients with osteoarthritis undergoing primary TKA using five different brands of posterior-stabilized implant.

Patients and Methods

Using our institutional registry, we identified 4135 patients who underwent TKA using one of the five most common brands of implant. These included Biomet Vanguard (Zimmer Biomet, Warsaw, Indiana) in 211 patients, DePuy/Johnson & Johnson Sigma (DePuy Synthes, Raynham, Massachusetts) in 222, Exactech Optetrak Logic (Exactech, Gainesville, Florida) in 1508, Smith & Nephew Genesis II (Smith & Nephew, London, United Kingdom) in 1415, and Zimmer NexGen (Zimmer Biomet) in 779 patients. Patients were evaluated preoperatively using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Lower Extremity Activity Scale (LEAS), and 12-Item Short-Form Health Survey questionnaire (SF-12). Demographics including age, body mass index, Charlson Comorbidity Index, American Society of Anethesiologists status, sex, and smoking status were collected. Postoperatively, two-year KOOS, LEAS, SF-12, and satisfaction scores were compared between groups.

Results

Outcomes were available for 4069 patients (98%) at two years postoperatively. In multiple regression analysis, which separately compared each implant group with the aggregate of all others, there were no clinically significant differences in the change of KOOS score from baseline to two-year follow-up between any of the groups. More than 80% of patients in each group were satisfied at this time in all domains. In a multivariate regression model, patients in the NexGen group were the most likely to be satisfied (odds ratio (OR) 1.63; p = 0.006) and Optetrak Logic patients were the least likely to be satisfied (OR 0.60; p < 0.001).

Conclusion

TKA provides improvement in function and satisfaction regardless of the type of implant. We could not demonstrate superiority of one design above others across these groups of implants, and any price premium for one above the other systems may not be justified. Healthcare administrators may find these similarities in outcomes helpful when negotiating purchasing contracts. Cite this article: Bone Joint J 2019;101-B(7 Supple C):48–54

Long-term results of total knee arthroplasty with single-radius versus multi-radius posterior-stabilized prostheses

Background

Single-radius (SR) prostheses and multi-radius (MR) prostheses have different theoretical advantages; however, there has been a paucity of evaluations comparing the two. This study was designed to compare the 10-year clinical, radiological, and survival outcomes of SR and MR posterior-stabilized prostheses in total knee arthroplasty (TKA).

Methods

In this retrospective cohort study, 220 consecutive patients undergoing TKA between October 2006 and October 2007 were divided into the SR group (106 patients, Stryker Scorpio NRG) and the MR group (114 patients, DePuy Sigma PFC), with a minimum follow-up of 10 years. Clinical, functional, and radiological outcomes, as well as satisfaction rates and survival results, were evaluated.

Results

Hospital for Special Surgery and Short Form-12 health survey scores were all significantly improved in both groups at the final follow-up (P < 0.05), but the groups did not differ. The SR group had significantly less anterior knee pain (AKP) and painless crepitation (P < 0.05). Radiological results in terms of radiolucent lines and component position angle showed no differences between groups. The Kaplan-Meier survival curve estimates at 10 years were not significantly different between the groups (P = 0.4172).

Conclusion

Both SR and MR posterior-stabilized prostheses can lead to satisfactory outcomes. The SR prosthesis design gave less anterior knee pain than did the MR prostheses. Two prostheses showed no differences in terms of clinical scales, radiological results, satisfaction rates, and survival results at a long-term follow-up. More accurate measurements are required.

Excellent 10-year patient-reported outcomes and survival in a single-radius, cruciate-retaining total knee arthroplasty

PURPOSE

Over 2 million Triathlon single-radius total knee arthroplasties (TKAs) have been implanted worldwide. This study reports the 10-year survival and patient-reported outcome of the Triathlon TKA in a single independent centre.

METHODS

From 2006 to 2007, 462 consecutive cruciate-retaining Triathlon TKAs were implanted in 426 patients (median age 69 (21-89), 289 (62.5%) female). Patellae were not routinely resurfaced. Patient-reported outcome measures (SF-12, Oxford Knee Scores (OKS), satisfaction) were assessed preoperatively and at 1, 5 and 10 years when radiographs were reviewed. Forgotten Joint Scores (FJS) were collected at 10 years. Kaplan-Meier survival analysis was performed.

RESULTS

At 10-11.6 years, 123 patients (128 TKAs) had died and 8 TKAs were lost to follow-up. There were four aseptic failures (two cases of tibial loosening, two cases of instability) and four septic failures requiring revision. Symptomatic aseptic radiographic loosening was present in three further cases at 11 years. Four (1%) patellae were secondarily resurfaced. OKS score improved by 17.7 ± 9.7 points at 1 year (p < 0.001), and was maintained at 34.7 ± 9.6 at 10 years with FJS 48.5 ± 31.4. Patient satisfaction was 88% at each timepoint. Ten-year survival was 97.9% (95% confidence interval 96.5-99.3) for revision for any reason, 98.9% (97.7-100) for mechanical failure, and 98.6% (97.4-99.8) for aseptic loosening (symptomatic radiographic or revised).

CONCLUSION

The Triathlon TKA continues to show excellent longer-term results with high implant survivorship, low rates of aseptic failure, consistently maintained PROMs and excellent patient satisfaction rates of 88% at 10 years.

LEVEL OF EVIDENCE

II, Prospective cohort study.

Is Patient Satisfaction Associated With Clinical Outcomes After Osteochondral Allograft Transplantation in the Knee?

BACKGROUND

The association between patient satisfaction and patient-reported outcomes after cartilage repair is not well understood.

PURPOSE

To investigate the association of patient satisfaction with pain, function, activity level, and quality of life after fresh osteochondral allograft (OCA) transplantation in the knee.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study comprised 371 patients (396 knees) who underwent primary OCA transplantation for osteochondral lesions in the knee between 1997 and 2015. Mean ± SD patient age was 31.8 ± 11.6 years, and 62% were male. The majority of grafts (62%) were located on the femoral condyle; the mean number of grafts per knee was 1.5 ± 0.8; and the median graft area was 6.9 cm² (range, 1.8-50 cm²). Pain, function, activity level, and quality of life were evaluated pre- and postoperatively via International Knee Documentation Committee scores and Knee injury and Osteoarthritis Outcome Scores. Patient satisfaction with the results of the OCA transplantation was assessed postoperatively. All follow-up evaluations occurring at postoperative 1 year or later were included in the analysis.

RESULTS

The mean follow-up time was 5.5 years. Overall, the satisfaction rate was 88.1%, and this rate was constant over time. Satisfaction rates varied by diagnosis, age, sex, and anatomic location of the allograft. Postoperative International Knee Documentation Committee pain, function, and total scores differed between patients who were satisfied and not satisfied (all P < .001). All Knee injury and Osteoarthritis Outcome Score subscale results differed between those who were satisfied and not satisfied (all P < .001). Having a diagnosis of osteochondritis dissecans was the only variable that predicted which patients would be satisfied with the results of the allograft, after controlling for age, sex, anatomic location of the graft, and number of grafts.

CONCLUSION

A consistently high and durable patient satisfaction rate after OCA transplantation was found. Satisfied patients reported lower pain and higher function, activity levels, and quality of life as compared with patients who were not satisfied. Patients with osteochondritis dissecans had a particularly high level of satisfaction with the OCA procedure.

Prospective Randomized Comparison of Posterior-Stabilized Versus Condylar-Stabilized Total Knee Arthroplasty: Final Report of a Five-Year Study

BACKGROUND

This report presents the minimum 5-year results of a prospective, randomized, Level of Evidence I study that evaluated cruciate-sacrificing total knee arthroplasty using either a posterior-stabilized (PS) device or a condylar-stabilized (CS) device. We hypothesized that the clinical outcomes of both groups would be equivalent and that there would be differences in operative time and/or blood loss parameters.

METHODS

One-hundred eleven patients undergoing total knee arthroplasty were randomized to receive either a post-cam style tibial insert (PS, n = 56) or a more congruent anterior-lipped tibial insert (CS, n = 55). All posterior cruciate ligaments were sacrificed.

RESULTS

Comparison of the clinical scores and radiographic results between both groups were essentially equivalent with no statistically significant differences at the final 5-year evaluation, although the CS knee group had significantly fewer incidences of postoperative mechanical sensations (P = .01).

CONCLUSION

These results demonstrate that the CS knee provides excellent clinical, functional, and radiographic outcomes that are comparable to the results achieved with the PS knee, with a lower incidence of mechanical sensations, and support the use of a CS device as an alternative to the PS device.

Quality of life after total knee arthroplasty

Total knee arthroplasty (TKA) results in a high degree of patient satisfaction, as it provides patients with considerable medium- and long-term benefits in terms of quality of life, pain relief and function. Nevertheless, the literature reports that up to 30% of patients are dissatisfied. This dissatisfaction is directly related to the patients' quality of life, which they deem insufficient. Their quality of life depends on many physical, behavioural, social and psychological factors that are not taken into account by functional outcome scores. After describing the principles of quality of life evaluation after TKA, we will assess the effects of patient-related factors, the surgical technique and postoperative program through an exhaustive review of the literature. Patient expectations after TKA will then be outlined, particularly return to work and return to sports.

Articular surface mounted navigated total knee arthroplasty improves the reliability of component alignment

PURPOSE

The primary aim was to compare the early knee-specific functional outcome after articular surface mounted (ASM) navigation with non-navigated TKA. The secondary aims were to compare general physical and mental health improvement, patient satisfaction, and reliability of component alignment in the sagittal and coronal planes between ASM navigated TKA with that of non-navigated TKA.

METHODS

Prospective functional outcome and radiographic data were collect for 123 patients undergoing ASM navigation and 172 patients undergoing non-navigated TKA by a high volume single surgeon. Pre-operative and one-year Oxford knee score (OKS) and short form (SF-) 12 scores were collected. Patient satisfaction was also assessed at one year. Implant position was assessed on post-operative radiographs (alpha, beta, gamma, and sigma angles) by a blinded observer.

RESULTS

There was no significant difference for improvement in OKS, SF-12 physical or mental components, or satisfaction between the groups one year following surgery. The non-navigation group was significantly more likely to have outliers (greater than 3 degrees) in femoral varus/valgus coronal alignment [odds ratio (OR) 4.5, 95% confidence interval (CI) 1.0-20.7, p = 0.049] and for posterior tibial slope (OR 8.3, 95% CI 1.1-65.0, p = 0.03).

CONCLUSIONS

ASM navigation significantly reduces the number of outliers for the femoral and tibial components when compared to conventional non-navigation alignment. However, the short-term functional outcome is not influenced by the surgical technique used. If the surgeon wants to reduce their number of outliers, then ASM navigation should be considered but the overall functional outcome in the short term is not influenced.

LEVEL OF EVIDENCE

III Therapeutic investigation, retrospective cohort study.

Better functional outcome after single-radius TKA compared with multi-radius TKA

PURPOSE

To determine whether the design of the femoral component influenced patient outcomes.

METHODS

Two hundred and thirty-seven patients were randomized to compare functional outcomes between single-radius TKA (SR, 118 patients) and multi-radius TKA (MR, 119 patients) with a minimum follow-up of 5 years. Prospective pre- and postoperative assessments were performed by the clinical and radiological criteria of the Knee Society Score (KSS), WOMAC and Short-Form 12 (SF12) questionnaires. The extension mechanism was assessed based on the quadriceps strength and chair test. Patient satisfaction was also assessed.

RESULTS

The median follow-up was 5.7 (range 5-7) years. At last follow-up, significant better KSSs (p = 0.001), range of motion (p = 0.001), extension lag (p = 0.020), quadriceps strength (p = 0.004), chair test (p = 0.032) and WOMAC pain (p = 0.002) were found in the SR group. Moreover, the improvements of these variables were early in the SR group (from 6 postoperative months). There were no significant differences in WOMAC function or SF12 physical and mental components. The revision rate and implant survival were similar in both groups. Satisfaction rate was significantly higher in SR group (p = 0.032).

CONCLUSION

This study shows better results with SR cruciate-retaining femoral component than MR component. The use of SR system is recommended because, although the clinically relevant differences were moderate, the functional improvement was earlier and the patient satisfaction higher with this design.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Performance Comparison of Single-Radius Versus Multiple-Curve Femoral Component in Total Knee Arthroplasty: A Prospective, Randomized Study Using the Lower Quarter Y-Balance Test

Midflexion stability after total knee arthroplasty (TKA) is dependent, in part, on implant design. Midflexion performance of a single-radius (SR) design and a multi-radius, or J-curve (JC), design were compared using the Lower Quarter Y-Balance Test (YBT-LQ). Patient-reported outcomes and measures of physical performance were also compared. The authors hypothesized that the SR design would provide superior midflexion stability and, therefore, a greater reach distance in the YBT-LQ when compared with the JC design. Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or the JC (n=30) implant. Patients reported outcome measures (Knee Injury and Osteoarthritis Outcome Score, Knee Society Score, and University of California at Los Angeles Activity Score), performed the YBT-LQ, and completed physical performance measures (walking speed, timed up-and-go test, and sit-to-stand test) before surgery and 1 year postoperatively. One year postoperatively, 40 patients (20 SR, 20 JC) were available for analysis. There were no significant differences between the groups regarding age, sex, body mass index, American Society of Anesthesiologists score, YBT-LQ results, or any other variable of interest. In both groups, significant improvements were observed for all variables of interest when compared from preoperatively to 1 year postoperatively. Implant type did not affect patient-reported or physical performance outcomes following TKA; however, patients showed significant improvement in most outcome measures by 1 year postoperatively. The significant limitations in strength and balance in this cohort of patients likely outweigh any subtle differences in implant design. [Orthopedics. 2017; 40(6):e1074-e1080.].

Comparison of fixed and mobile-bearing total knee arthroplasty in terms of patellofemoral pain and function: a prospective, randomised, controlled trial

BACKGROUND

Despite growing evidence in the literature, there is still a lack of consensus regarding the use of the mobile-bearing (MB) design total knee arthroplasty (TKA).

METHODS

In a prospective, comparative, randomised, single centre trial, 106 patients with end-stage osteoarthritis of the knee were randomised to either an MB or fixed-bearing (FB) group to receive posterior stabilised (PS)-TKA using a standard medial parapatellar approach and patellar resurfacing with follow-up (FU) for 5 years. The primary outcome was anterior knee pain (AKP) during the chair rise test and the stair climb test 5 years after surgery. The secondary outcome was the ability to rise from a chair and to climb stairs, range of motion (ROM), Knee Society Score (KSS), RAND-36 scores and radiological analysis of the patellar tilt.

RESULTS

No statistically significant difference was found between the two groups at 5 years FU in terms of median AKP during the chair rise test and the stair climb test (p = 0.5 and p = 0.8, respectively). There was no significant difference in any of the other secondary outcome parameters between the groups at 5 years FU.

CONCLUSION

A mobile-bearing TKA does not decrease AKP compared to fixed bearings.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02892838 .

LEVEL OF EVIDENCE

II.

Aseptic Revision Knee Arthroplasty With Total Stabilizer Prostheses Achieves Similar Functional Outcomes to Primary Total Knee Arthroplasty at 2 Years: A Longitudinal Cohort Study

BACKGROUND

Patient function is poorly characterized following revision total knee arthroplasty (TKA), although is generally accepted to be inferior to that following primary procedures.

METHODS

Fifty-three consecutive aseptic revisions to total stabilizer devices were prospectively evaluated, preoperatively and at 6, 26, 52, and 104 weeks postoperatively, using the Oxford Knee Score (OKS), range of motion, pain rating scale, and timed functional performance battery. Data were assessed longitudinally and in comparison to primary TKA data with identical outcome assessments at equivalent time points.

RESULTS

Mean outcome changes were: 13 point increase in the OKS (from 17.5 [standard deviation-SD 7.4]-32.4 [SD 7.9] points); 21 degree improvement in the knee flexion (80.6 [SD 20.5]-101.5 [SD 13.2] degrees); 60% reduction in the pain report (7.7 [SD 2.3]-1.3 [SD 0.4] points); and 15 second improvement in the timed performance assessment (47.2 [SD 19.1]-32.0 [SD 7.0] seconds; P < .001). No difference was seen between primary and revision cohorts in OKS or pain scores (analysis of variance, P = .2 and .19). Knee flexion and timed performance assessment were different between primary and revision groups (analysis of variance, P = .03 and P = .02); however, this was due to differing preoperative values. The revision cohort achieved the same postoperative scores as the primary cohort at all postoperative time points.

CONCLUSION

Patients undergoing revision TKA for aseptic failure with total stabilizer implants made substantial improvements in the initial 2 years following surgery in both patient-reported and directly assessed function, comparable with that achieved following primary knee arthroplasty.

Validation of the English language Forgotten Joint Score-12 as an outcome measure for total hip and knee arthroplasty in a British population

Aims

To validate the English language Forgotten Joint Score-12 (FJS-12) as a tool to evaluate the outcome of hip and knee arthroplasty in a United Kingdom population.

Patients and Methods

All patients undergoing surgery between January and August 2014 were eligible for inclusion. Prospective data were collected from 205 patients undergoing total hip arthroplasty (THA) and 231 patients undergoing total knee arthroplasty (TKA). Outcomes were assessed with the FJS-12 and the Oxford Hip and Knee Scores (OHS, OKS) pre-operatively, then at six and 12 months post-operatively. Internal consistency, convergent validity, effect size, relative validity and ceiling effects were determined.

Results

Data for the TKA and THA patients showed high internal consistency for the FJS-12 (Cronbach α = 0.97 in TKAs, 0.98 in THAs). Convergent validity with the Oxford Scores was high (r = 0.85 in TKAs, r = 0.79 for THAs). From six to 12 months, the change was higher for the FJS-12 than for the OHS in THA patients (effect size d = 0.21 versus -0.03). Ceiling effects at one-year follow-up were low for the FJS-12 with just 3.9% (TKA) and 8.8% (THA) of patients achieving the best possible score.

Conclusion

The FJS-12 has strong measurement properties in terms of validity, internal consistency and sensitivity to change in TKA and THA patients. Low ceiling effects and good relative validity allow the monitoring of longer term outcomes, particularly in well-performing groups after total joint arthroplasty. Cite this article: Bone Joint J 2017;99-B:218–24.

Factors that shape the patient's hospital experience and satisfaction with lower limb arthroplasty: an exploratory thematic analysis

OBJECTIVE

It is generally accepted that the patients' hospital experience can influence their overall satisfaction with the outcome of lower limb arthroplasty; however, little is known about the factors that shape the hospital experience. The aim of this study was to develop an understanding of what patients like and do not like about their hospital experience with a view to providing insight into where service improvements could have the potential to improve the patient experience and their satisfaction, and whether they would recommend the procedure.

DESIGN

A mixed methods (quan-QUAL) approach.

SETTING

Large regional teaching hospital.

PARTICIPANTS

216 patients who had completed a postoperative postal questionnaire at 12 months following total knee or total hip arthroplasty.

OUTCOME MEASURES

Overall satisfaction with the outcome of surgery, whether to recommend the procedure to another and the rating of patient hospital experience. Free text comments on the best and worst aspects of their hospital stay were evaluated using qualitative thematic analysis.

RESULTS

Overall, 77% of patients were satisfied with their surgery, 79% reported a good-excellent hospital experience and 85% would recommend the surgery to another. Qualitative analysis revealed clear themes relating to communication, pain relief and the process experience. Comments on positive aspects of the hospital experience were related to feeling well informed and consulted about their care. Comments on the worst aspects of care were related to being made to wait without explanation, moved to different wards and when they felt invisible to the healthcare staff caring for them.

CONCLUSIONS

Positive patient experiences were closely linked to effective patient-health professional interactions and logistics of the hospital processes. Within arthroplasty services, the patient experience of healthcare could be enhanced by further attention to concepts of patient-centred care. Practical examples of this include more focus on developing staff-patient communication and the avoidance of 'boarding' procedures.

Meta-Analysis of Outcomes of a Single-Radius Versus Multi-Radius Femoral Design in Total Knee Arthroplasty

BACKGROUND

Although the single-radius (SR) femoral design is known to have theoretical advantages in many aspects, studies of clinical outcomes that compare the SR with the multiple-radius (MR) femoral design are controversial. We performed a meta-analysis to address the hypothesis that a SR femoral design in primary total knee arthroplasty improves patient outcomes.

METHODS

The meta-analysis identified 15 articles reporting the clinical outcomes of 2212 knee replacements using the SR (n = 948) compared with the multiradius (MR; n = 1361) femoral design. Comparing SR with MR, we examined the Knee Society Score for the knee (KSS-knee), KSS-function, knee flexion, range of motion, complications, isometric peak torque of knee, and survival rate.

RESULTS

The range of motion of SR knees was lower than that of MR knees. No differences were found in the analyses of KSS-knee, KSS-function, knee flexion, complications, isometric peak torque of the knee, and survival rate.

CONCLUSION

Our meta-analysis does not provide clinical support for the previously reported theoretical advantages of the SR implant design.

Patient Satisfaction after Total Knee Arthroplasty

Total knee arthroplasty (TKA) is one of the most successful and effective surgical options to reduce pain and restore function for patients with severe osteoarthritis. The purpose of this article was to review and summarize the recent literatures regarding patient satisfaction after TKA and to analyze the various factors associated with patient dissatisfaction after TKA. Patient satisfaction is one of the many patient-reported outcome measures (PROMs). Patient satisfaction can be evaluated from two categories, determinants of satisfaction and components of satisfaction. The former have been described as all of the patient-related factors including age, gender, personality, patient expectations, medical and psychiatric comorbidity, patient's diagnosis leading to TKA and severity of arthropathy. The latter are all of the processes and technical aspects of TKA, ranging from the anesthetic and surgical factors, type of implants and postoperative rehabilitations. The surgeon- and patient-reported outcomes have been shown to be disparate occasionally. Among various factors that contribute to patient satisfaction, some factors can be managed by the surgeon, which should be improved through continuous research. Furthermore, extensive discussion and explanation before surgery will reduce patient dissatisfaction after TKA.