Long-term follow-up of a non-randomised prospective cohort of one hundred and ninety two total knee arthroplasties using the NexGen implant

Accuracy and clinical outcomes in total knee arthroplasty using an image-free navigation system

INTRODUCTION

The purpose of this study was to investigate the accuracy of an image-free navigation system and to investigate the effect of the postoperative coronal lower limb alignment and implant alignment on clinical outcomes following mechanically aligned (MA)-total knee arthroplasty (TKA).

MATERIALS AND METHODS

In this retrospective study, 180 primary cemented posterior-stabilized TKAs were performed using an image-free navigation system. Patients were divided into groups based on their postoperative hip-knee-ankle angle (HKA; a neutral HKA group [0 ± 3°] and an outlier group [<-3° or > 3°]), lateral distal femoral angle (LDFA; a neutral LDFA group [90 ± 3°] and an outlier group [< 87° or > 93°]), and medial proximal tibial angle (MPTA; a neutral MPTA group [90 ± 3°] and an outlier group [< 87° or > 93°]). The range-of-motion, 2011 Knee Society score (2011 KSS), and Forgotten Joint Score-12 (FJS-12) were compared between the neutral and outlier groups at 1 and 2 years postoperatively.

RESULTS

The percentage of knees with a neutral HKA was 91.1% and clinical outcomes significantly improved postoperatively. No significant differences were detected between the neutral HKA (n = 164) and outlier groups (n = 16, all varus) for any clinical outcome. Considering LDFA, the outlier group was too small (n = 3, all varus) for statistical analysis. The overall 2011 KSS and symptoms at 2 years postoperatively and FJS-12 at 1 and 2 years postoperatively were significantly higher in the neutral MPTA group (n = 174) than in the outlier group (n = 6, all varus).

CONCLUSIONS

The accuracy of an image-free navigation system was satisfactory in MA-TKA and led to good clinical outcomes. No significant differences in clinical outcome were detected between postoperative patients with an HKA within 3° of the neutral position and postoperative patients with an HKA <-3°. Patients with a postoperative MPTA within 90 ± 3° achieved better clinical outcomes than those of patients with an MPTA < 87°.

Fixation options for total knee arthroplasty: a comprehensive literature review

Total knee arthroplasty is a consistently successful, cost-efficient, and highly effective surgical procedure for treating severe knee osteoarthritis. The success and longevity of total knee arthroplasty depend significantly on the fixation method used to secure the prosthetic components. This comprehensive review examines the primary fixation methods (cemented, cementless, and hybrid fixation), analysing their biomechanics, clinical outcomes, advantages, and disadvantages, focusing on recent advances and trends in total knee arthroplasty fixation.

Minimum 19-Year Clinical Results and Patient Satisfaction After Total Knee Arthroplasty

BACKGROUND

Long-term (minimum 19-year) outcome data on clinical results and patient satisfaction after posterior-stabilized total knee arthroplasties (TKAs) are missing in the literature. The purpose of the study was to evaluate the clinical and radiographic results as well as patient satisfaction at a mean of 21.2 years after posterior-stabilized TKAs.

METHODS

This study included 756 patients (1,350 knees) who had undergone TKAs. There were 96 men and 660 women (mean age, 58 years; range, 40 to 84). The mean follow-up was 21.2 years (range, 19 to 23). At each follow-up visit, the patients were assessed radiographically and clinically. Furthermore, patient satisfaction was determined.

RESULTS

The Knee Society total, pain, function, and deformity scores were 42, 18, 33, and 5 points, respectively, at the final follow-up. The mean Western Ontario and McMaster Universities Arthritis Index score was 25 points at the final follow-up. With revision or aseptic loosening as the end point, the 23-year intimated survival for the implant was 96% (95% confidence interval, 91 to 100%). The overall patient satisfaction score at the final follow-up was 83.3 points (range, 81 to 86). Patient satisfaction scores with regard to pain, housework, recreation, and surgery were 84, 81, 82, and 86 points, respectively.

CONCLUSIONS

The findings of the present, mean 21-year follow-up clinical study suggest excellent results with regard to the revision rates and survivorship of the posterior-stabilized total knee implants. However, consistent with the literature, we found that about 80% of patients expressed overall satisfaction with their primary TKAs. About 8% of patients were either somewhat or very dissatisfied with the procedure.

Third-generation posterior-stabilised cemented system for total knee arthroplasty: Survivorship and outcomes after 20-year follow-up

Purpose

Total knee arthroplasty is a common procedure due to increased life expectancy and ageing populations, necessitating implants with long-term efficacy. After some initial designs, the third-generation modular posterior-stabilised NexGen® prosthesis aimed to enhance kinematics and reduce complications. This study evaluates the long-term outcomes, survivorship, revision rates and complications of this implant. With promising results observed up to 15 years in previous studies, this investigation aims to assess the implant's performance over extended follow-up periods, aiding in optimal implant selection for improved patient outcomes.

Methods

We carried out a retrospective study on 263 total knee arthroplasties performed in our centre between 1998 and 2002. Statistical analysis of complications was performed and study of survival using the Kaplan-Meier method and competing risk analysis were calculated. Description of reinterventions and complications were also included.

Results

Results show a 20-year prosthesis survival rate of 90.8% for revision due to any reason, with an estimated survival of 92.3% considering competitive events. Estimated survivorship at 20 years is 98% for aseptic loosening as the end point, and an estimation of 98.80% considering competitive events. Twenty revisions were performed, with 10 cases due to infection and 10 for noninfectious reasons and three of them due to aseptic loosening. Radiographic analysis revealed radiolucent lines, but no clinical evidence of loosening was observed in these cases.

Conclusion

This study offers survivorship data from longer follow-up periods, what is difficult to find in the reported literature and showed excellent results of this implant in terms of survivorship and low rates of revision in our cohort.

Level of Evidence

Level IV.

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.

The modification of bone cut angle and joint line obliquity did not change the tibiofemoral kinematics and stability of knee joint after total knee arthroplasty

INTRODUCTION

Previous reports using cadaveric knees and musculoskeletal computer simulation have shown that kinematically aligned (KA) total knee arthroplasty (TKA) provides more natural and physiological tibiofemoral kinematic patterns than mechanically aligned (MA) TKA. These reports suggested that the modification of joint line obliquity improve the knee kinematics. This study aimed to determine whether joint line obliquity change the intraoperative tibiofemoral kinematics in TKA candidates with knee osteoarthritis.

METHODS

Thirty consecutive knees with varus osteoarthritis that underwent TKA using a navigation system were evaluated. Two types of trial components were prepared: (1) MA TKA model: component trial in which articulating surface was parallel to the bone cut surface (2) KA TKA model: the femoral component trial, which mimicked the KA TKA method of Dossett et al. was designed 3° valgus and 3° internal rotation to the femoral bone cut surface, and the tibial component trial was designed 3° varus to the tibial bone cut surface. These two trials were set on the same knees during the operation, and the tibiofemoral rotational kinematics and varus-valgus laxity were measured from 0° to 120° of knee flexion using a navigation system.

RESULTS

The joint gap was 20 ± 2 mm and 3° ± 1° varus in extension and 20 ± 2 mm and 3° ± 1°varus in flexion. The differences in femoral component rotation between KA TKA and MA TKA were not statistically significant for any knee flexion angle. The differences in varus-valgus laxity between KA TKA and MA TKA were also not statistically significant for any knee flexion angle.

CONCLUSION

Although the degree of joint line obliquity varies widely in various KA TKA methods, this study, which mimicked the method of Dossett et al. showed that the modification of joint line obliquity did not change the tibiofemoral kinematics and stability of the knee joint in TKA candidates with knee osteoarthritis.

Long-term outcomes of the Nexgen© posterior stabilized knee: minimum 15 year follow-safe and effective

PURPOSE

Studying long-term survivorship and functional outcomes for specific prostheses is critical for elucidating areas in need of design improvement. This study reports the long-term of the NexGen Posterior Stabilized (PS) Total Knee implant (TKA) (Zimmer Biomet, Warsaw IN) Performed by a single surgeon.

METHODS

Data from patients treated with the NexGen PS TKA between January 2003 and December 2005 with a minimal follow-up of 15 years was collected from a prospectively collected database. Survivorship rates and Oxford Knee Scores (OKS) were obtained for those patients available for follow-up.

RESULTS

Ninety-five patients met the inclusion criteria during the study period. OKS was available for 44 (46%) patients. Ten patients required revision surgery (10.52%). Implant-specific survivorship of all cases that were reviewed was 98%. Survivorship of implants in patients that we were able to reach, or deceased patients was 93%. The average Oxford Knee Score was 39.1 (14-48. SD ± 7.70) with 48 being the maximal score.

CONCLUSION

Despite some concerns about durability of this implant, good longevity and function was demonstrated. At a minimum of 15 years follow-up in this cohort. Given these results design features of this system should be considered for future generations of implants.

Effects of 24 Weeks of a Supervised Walk Training on Knee Muscle Strength and Quality of Life in Older Female Total Knee Arthroplasty: A Retrospective Cohort Study

Poor supervision, impaired exercise adherence, and low compliance with exercise regimens result in inconsistent effects regarding exercise interventions. A supervised-walk training regimen (9 km/week) may have a positive effect on functional recovery in female total knee arthroplasty (TKA). This study aimed to evaluate the effect of a supervised walking regimen on lower limb muscle strength, functional fitness, and patient-reported outcomes in female TKA. Twenty-eight female TKA were allocated into a control (CON) (n = 14) or walk training (WT) (n = 14) group. WT on treadmills was initiated 12 weeks after TKA. All patients were examined for lower muscle strength (including extension and flexion of hip and knee), physical function (including a 6-min walk test, 8-foot up-and-go test, and 30-s chair stand test), and Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Knee flexor (WT: CON; 64.4 ± 4.1 nm/kg: 43.7±3.3 nm/kg; p = 0.001; effect size: 5.62) and extensor strengths (WT: CON; 73.1 ± 7.5 nm/kg: 48.2 ± 2.4 nm/kg; p = 0.001; effect size: 4.47) statistically increased in the WT group compared to the CON group. The 6-min walk test (from 341.3 ± 20.5 m to 405.5 ± 30.7 m; p = 0.001; effect size: 2.46) and 8-foot up-and-go test (from 9.5 ± 0.7 s to 8.3 ± 0.7 s; p = 0.002; effect size: 1.71) tests also showed significant improvements in the WT group in the follow-up compared to the baseline. An increase in quality of life score according to the KOOS questionnaire (WT: CON; 91.0 ± 2.8: 68.1 ± 5.8; p = 0.001; effect size: 5.02) was noted in the WT group compared to the CON group in the follow-up. WT facilitated improvements in knee muscle strength and functional outcomes in TKA patients.

The influence of alignment in long-term functional outcome of total knee arthroplasty

BACKGROUND

This study aimed to analyze long-term survival rate and clinical outcomes of a NexGen LPS knee system. The effect of component alignment parameters on clinical scores and patient satisfaction was also investigated.

METHODS

Between June 2002 and January 2010, 204 knees of 152 patients underwent total knee arthroplasty with NexGen LPS-Flex knee system with fix bearings. The mean follow-up was 13.2 (range, 10 to 18 years). The relationship between radiologic and clinical results was investigated with component angles. Outlier angles were determined according to cutoff values of alpha, beta, gamma, and delta angles on the radiographs taken immediately after the operation. Knees were classified based on existing outliers they have as "No Outliers" (Group 1), "Single Outliers" (Group 2), and "Multiple Outliers" (Group 3).

RESULTS

Revision surgery was required for ten patients, and the overall survival rate was 95.1% at the last follow-up. "Single Outliers" did not show a clinically significant difference in functional scores compared to the "No Outliers" group. However, KSKS and FJS-12 were significantly lower in "Multiple Outliers" knees (p: 0.039 and 0.019, respectively).

CONCLUSION

NexGen LPS-Flex knee system has satisfactory results with 95.1% implant survival in 13.2 years. FJS-12 measurements at the end of the follow-up demonstrate a favourable result of the fixed bearing design. On two plane X-ray evaluations, components malaligned with two or more outliers in the same knee deteriorate patient satisfaction and clinical results.

A comparison of SanatMetal Sanat Swing and Zimmer NexGen® total knee implants: 10-year postoperative follow-up results

Objectives

In this study, we present our 10-year postoperative follow-up results of Sanat Swing® and NexGen® total knee implants.

Patients and methods

A total of 189 patients (93 males, 96 females; mean age: 68 years; range, 48 to 86 years) who underwent total knee replacement between January 2008 and September 2010 were retrospectively analyzed. A total of 105 patients (Group A) were implanted a cemented Sanat Swing knee prosthesis and 84 patients (Group B) were implanted a cemented NexGen knee prosthesis. Operation time, range of motion (ROM), pain level, Knee Society Score (KSS), distance of painless walking, and the ability to climb stairs were evaluated between the groups.

Results

The mean follow-up was 10.8 (range, 9.8 to 12.3) years. No significant difference was observed in the survival of the prostheses, ROM, pain level, KSS, walking distance, and in the ability to climb stairs between the two groups at 10 years. With an experienced team, the operation time was about 4 to 5 min shorter in the Sanat Swing implantation group. In selected cases, Sanat Swing was superior to the NexGen system; however, there was no statistically significant difference. Complication rates were also low and comparable between both groups.

Conclusion

Based on the 10 years of follow-up evaluation, Sanat Swing total knee replacement system seems to yield comparable clinical results with the NexGen. Experiences with the operative technique and comparative evaluation, the Sanat Swing system is a safe and reliable alternative for total knee replacement, providing a user-friendly operative technique and shorter operation time.

Rotational and varus-valgus laxity affects kinematics of the normal knee: A cadaveric study

PURPOSE

The aim of this study was to evaluate the relationship between soft tissue laxity and kinematics of the normal knee using a navigation system.

METHODS

Fifteen cadaveric knees from 11 fresh frozen whole-body specimens were included in this study. The navigation system automatically recorded the rotation angle of the tibia as the internal-external (IE) kinematics and the coronal alignment of the lower limb as the varus-valgus (VV) kinematics. These measurements were made with the joint in maximal extension, at 10° intervals from 0° to 120° of flexion, and at maximal flexion during passive knee motion. For evaluation of laxity, the examiner gently applied maximum manual IE and VV stress to the knee at 0°, 30°, 60°, and 90° of flexion.

RESULTS

The measurements showed almost perfect reliability. The mean correlation coefficient between the intraoperative tibial rotation angle and the intermediate angle of IE laxity was 0.82, while that between the coronal alignment of the lower limb and the intermediate angle of the VV laxity was 0.96. There was a statistically significant correlation between kinematics and laxity at all degrees of knee flexion.

CONCLUSION

The present study revealed that the rotation angle of the tibia was correlated to the intermediate angle of IE laxity at 0°, 30°, 60°, and 90° of knee flexion and the coronal alignment of the lower limb also correlated to the intermediate angle of VV laxity. These findings provide important reference data on soft tissue laxity and kinematics of the normal knee.

Comparison of Modular Conventional and High-Flexion Posterior-Stabilized Total Knee Arthroplasties in the Same Patients at a Mean Follow-Up of 15 Years

BACKGROUND

As previous studies are limited to short-term clinical data on conventional and high-flexion total knee arthroplasties (TKAs), long-term clinical data on these TKAs remain unclear. Therefore, we evaluated long-term functional outcome, range of knee motion, revision rate, implant survival, and the prevalence of osteolysis after conventional and high-flexion TKAs in the same patients.

METHODS

The authors evaluated a cohort of 1206 patients with a mean age of 65.3 ± 7 years (range: 22-70) who underwent bilateral simultaneous sequential TKAs. One knee received a conventional TKA and the other received a high-flexion TKA. The mean duration of follow-up was 15.6 years (range: 14-17).

RESULTS

No significant differences were found between the 2 groups at the latest follow-up with respect to Knee Society score (93 vs 92 points, P = .765), pain score (45 vs 44 points, P = .641), range of knee motion (125° vs 126°, P = .712), and radiographic and computed tomography scan results. Furthermore, no significant revision rate differences were found between the 2 groups (1.3% for conventional TKA vs 1.6% for high-flexion TKA; P = .137). There was no osteolysis recorded in either group. The rate of survivorship free of implant revision or aseptic loosening was 98.7% (95% CI = 91-100) for conventional TKA and 98.4% (95% CI = 91-100) for high-flexion TKA at 17 years.

CONCLUSION

At the latest follow-up, we were not able to demonstrate any significant difference between conventional and high-flexion TKAs with respect to functional outcome scores, range of knee motion, revision rate, implant survival, and prevalence of osteolysis.

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.

The medial constrained insert restores native knee rotational kinematics after bicruciate-retaining total knee arthroplasty

PURPOSE

The aim of this study was to test the hypothesis that the medial constrained insert would reproduce the native knee kinematics after bicruciate-retaining (BCR) total knee arthroplasty (TKA).

METHODS

Using an image-free navigation system in six fresh-frozen whole-body cadavers, the rotation angle of the tibia at minimum flexion, at 10° intervals from 0° to 130° flexion, and at maximum flexion during manual passive knee flexion was assessed. The data was collected in native knees, in BCR TKA using a normal flat insert (BCR-XP), and in BCR TKA using a more constrained insert in the medial side (BCR-AS). The differences in the rotation angle of the tibia were statistically evaluated.

RESULTS

The rotation angles of the tibia in BCR-XP were significantly different from those of the native knees both in the early flexion phase (p = 0.002 at minimum knee flexion, p = 0.002 at 0°, p = 0.041 at 10°, p = 0.009 at 20°, p = 0.026 at 30°) and in the late flexion phase (p = 0.015 at 130°, p = 0.015 at maximum knee flexion), whereas the rotational angles of the tibia in BCR-AS were similar to those of the native knee.

CONCLUSION

This study shows that the rotational kinematics of the native knee is reproduced after BCR TKA with the medial constrained insert. Surgeons and implant designers should be aware that constraint of the medial side in BCR TKA is a crucial factor for restoration of native kinematics which may lead to better clinical outcome.

Patellofemoral design enhancements reduce long-term complications of postero-stabilized total knee arthroplasty

PURPOSE

Few studies investigated whether trochlear and patellar design enhancements improve long-term outcomes of total knee arthroplasty (TKA). This study aimed to compare the long-term survival and complication rates of two consecutive generations of the same TKA system with identical tibiofemoral geometry, but different patellofemoral designs.

METHODS

The authors retrieved the records of 93 patients (104 knees) operated with the HLS II system and 116 patients (122 knees) operated with HLS Evolution system. Patients were evaluated preoperatively and at a minimum of 10 years noting all complications. Kaplan-Meier (KM) survival was compared for two endpoints: (1) revision of all components and (2) revision of any component.

RESULTS

From the HLS II series, the incidence of revision of all components was 6.4%, and of any component was 9.8%. From the HLS Evolution series, the incidence of revision of all components was 4.1%, and of any component was 5.1%. Comparing the survival at equivalent follow-up of 14 years, considering revision of all components, the HLS II had higher survival than the HLS Evolution (98.9% vs 95.9%), while considering revision of any component, the HLS II had lower survival than the HLS Evolution (93.0% vs 94.9%). The differences in survival of the two implants were not significant, neither at equivalent follow-up of 14 years (n.s.), nor at maximum follow-up of each cohort (n.s.). The complication rate was higher for the HLS II series compared to the HLS Evolution (28% vs 12%, p = 0.009), but patellofemoral complications were not more frequent (8% vs 6%, n.s.).

CONCLUSIONS

Though the differences in survival of the two implants were not significant, conflicting findings are observed due to partial revisions for patellar fractures (5 in the HLS II series and 1 in the HLS Evolution series) which could be related to patellofemoral design enhancements. This study highlights the importance of patello-femoral geometry, which is often overlooked in TKA.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up

BACKGROUND

Knee replacements are the mainstay of treatment for end-stage osteoarthritis and are effective. Given time, all knee replacements will fail and knowing when this failure might happen is important. We aimed to establish how long a knee replacement lasts.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE and Embase for case series and cohort studies published from database inception until July 21, 2018. Articles reporting 15 year or greater survival of primary total knee replacement (TKR), unicondylar knee replacement (UKR), and patellofemoral replacements in patients with osteoarthritis were included. Articles that reviewed specifically complex primary surgeries or revisions were excluded. Survival and implant data were extracted, with all-cause survival of the knee replacement construct being the primary outcome. We also reviewed national joint replacement registry reports and extracted the data to be analysed separately. In the meta-analysis, we weighted each series and calculated a pooled survival estimate for each data source at 15 years, 20 years, and 25 years, using a fixed-effects model. This study is registered with PROSPERO, number CRD42018105188.

FINDINGS

From 4363 references found by our initial search, we identified 33 case series in 30 eligible articles, which reported all-cause survival for 6490 TKRs (26 case series) and 742 UKRs (seven case series). No case series reporting on patellofemoral replacements met our inclusion criteria, and no case series reported 25 year survival for TKR. The estimated 25 year survival for UKR (based on one case series) was 72·0% (95% CI 58·0-95·0). Registries contributed 299 291 TKRs (47 series) and 7714 UKRs (five series). The pooled registry 25 year survival of TKRs (14 registries) was 82·3% (95% CI 81·3-83·2) and of UKRs (four registries) was 69·8% (67·6-72·1).

INTERPRETATION

Our pooled registry data, which we believe to be more accurate than the case series data, shows that approximately 82% of TKRs last 25 years and 70% of UKRs last 25 years. These findings will be of use to patients and health-care providers; further information is required to predict exactly how long specific knee replacements will last.

FUNDING

The National Joint Registry for England, Wales, Northern Ireland, and Isle of Man and the Royal College of Surgeons of England.

Quality of life after staged bilateral total knee arthroplasty: a minimum five-year follow-up study of seventy-eight patients

PURPOSE

Although many studies have been performed to evaluate the quality of life (QOL) and patient satisfaction after total knee arthroplasty (TKA), almost all evaluations were performed in patients after unilateral TKA or in patients after mixed unilateral and bilateral TKA. Accordingly, this study aimed to evaluate QOL after staged bilateral TKA.

METHODS

A total of 78 patients who underwent staged bilateral TKA for varus knee osteoarthritis were included in this study. All patients had longitudinal follow-up evaluations for at least five years. QOL was assessed by the Japanese Knee Osteoarthritis Measure (JKOM), a disease-specific and patient-derived QOL measure for Japanese patients. Conventional objective outcome scales, including the Knee Society Score and the Timed Up and Go test, were also assessed. In addition, QOL and objective outcomes were compared between the younger (≤ 80 years, average 75.8 years) and older (> 80 years, average 84.7 years) age groups at the final follow-up.

RESULTS

Improvements in both JKOM and objective outcomes reached a plateau one year after staged bilateral TKA. Improvements were prolonged for more than five years. There were no statistically significant differences in JKOM or objective outcomes between the younger and older age groups, despite an 8.9-year difference in the average age.

CONCLUSIONS

This was the first longitudinal study to evaluate QOL and objective outcomes after staged bilateral TKA for a period of at least five years. Improvements in QOL and objective outcomes reached a plateau one year after staged bilateral TKA and were prolonged for more than five years. No significant differences were observed in outcome scores between the younger and older age groups.

Total knee arthroplasty in Italy: reflections from the last fifteen years and projections for the next thirty

PURPOSE

Annual rates of knee arthroplasty are increasing in all developed countries, imposing a significant economic and organizational burden; it is crucial to forecast the future need for knee arthroplasty, to assist stakeholders in planning strategies and investments, especially in a country like Italy, with the largest proportion of elderly citizens in Europe. Few epidemiological studies have been performed worldwide to estimate the demand for future knee replacement, and a variety of methods have been proposed.

METHODS

We investigated the epidemiology of knee arthroplasty performed in Italy in the last 15 years and projected incidence rates up to the year 2050, utilizing, comparing, and adapting the available methodologies.

RESULTS

From 2001 to 2016, 812,639 primary TKA were performed in Italy on patients over 40. The total number of surgeries increased by 262% with an average annual growth rate of 6.6%.

CONCLUSIONS

Adopting the best fitting projection method, an increase of 45% in incidence rate is expected for 2050.

Tibial internal rotation negatively affects clinical outcomes in total knee arthroplasty: a systematic review

PURPOSE

The aim of this systematic review is to analyze the effect of tibial rotational alignment after total knee arthroplasty (TKA) on clinical outcomes and assess the eventual cut-off values for tibial TKA rotation leading to poor outcomes.

METHODS

A detailed and systematic search from 1997 to 2017 of the Pubmed, Medline, Cochrane Reviews, and the Google Scholar databases was performed using the keyword terms "total knee arthroplasty", "total knee replacement", "tibial alignment", "tibial malalignement", "tibial rotation", "rotational error", "axis", "angle", "tibial malrotation", "clinical outcome", in several combinations. The modified Coleman scoring methodology (mCMS) was used. All the primary TKAs studies analyzing correlation between clinical results and tibial rotation were included.

RESULTS

Five articles met the inclusion criteria. A total of 333 arthroplasties were included in this review; 139 had tibial component malalignment, while 194 were in control groups. The mean age of patients was 67.3 (SD 0.57) years. The mean average postoperative follow-up delay was 34.7 months (range 21-70). The mean mCMS score was 59.2 points indicating good methodological quality in the included studies. Functional outcomes were assessed through KSS, OKS, KOOS and VAS, negatively related to tibial internal rotation.

CONCLUSIONS

Our review confirmed that excessive internal rotation of the tibial TKA component represents a significant risk factor for pain and inferior functional outcomes after TKA (> 10° of internal rotation demonstrated the common value), since external rotation does not affect the results. However, a universal precise cut-off value has not been found in the available literature and there remains a debate about CT rotation assessment and surgical intra-operative landmarks.

LEVEL OF EVIDENCE

III.

Is Immediate Postoperative Mechanical Axis Associated with the Revision Rate of Primary Total Knee Arthroplasty? A 10-Year Follow-up Study

Background

Achieving neutral limb alignment during total knee arthroplasty (TKA) has been considered an important determinant in the long-term prosthesis survival. The purpose of this study was to evaluate the association between the immediate postoperative mechanical alignment of the lower limb and the rate of revision TKA by comparing an acceptable mechanical axis group (within ± 3° from neutral alignment) and an outlier group (> 3° deviation from neutral alignment).

Methods

Between 2000 and 2006, clinical and radiographic data of 334 primary TKAs were retrospectively reviewed to determine the 10-year Kaplan-Meier survival rate. Patients were divided into acceptable and outlier groups according to the mechanical axis checked postoperatively within a month. Clinical outcomes were assessed using Hospital for Special Surgery, Knee Society Score, and Western Ontario and McMaster Universities Osteoarthritis Index score preoperatively and at the final follow-up. Postoperative complications and revision rates were also evaluated.

Results

The mean change in mechanical axis between the immediate postoperative examination and the last follow-up was greater in the outlier group (1.6 ± 2.7) than in the acceptable group (0.8 ± 2.4). The revision rates were significantly different between the two groups (p = 0.04). At the last follow-up, clinical scores were all improved in both groups compared to each preoperative condition. There were no significant differences in clinical scores between the two groups at the last follow-up. The 10-year Kaplan-Meier survival analysis showed a tendency towards better survival with restoration of neutral mechanical axis. However, the difference was not statistically significant (p = 0.25).

Conclusions

Restoration of neutral limb alignment is a factor that can result in a lower revision rate and higher longevity in TKA. However, there were no significant differences in clinical outcomes between the two groups.

Knowledge and attitude towards total knee arthroplasty among the public in Saudi Arabia: a nationwide population-based study

PURPOSE

Studies on total knee arthroplasty (TKA) in Saudi Arabia are scarce, and none have reported the knowledge and attitude of the procedure in Saudi Arabia. Our study aims to measure the knowledge and attitude of TKA among the adult Saudi population.

METHODS

To encompass a representative sample of this cross-sectional survey, all 13 administrative areas were used as ready-made geographical clusters. For each cluster, stratified random sampling was performed to maximize participation in the study. In each area, random samples of mobile phone numbers were selected with a probability proportional to the administrative area population size. Sample size calculation was based on the assumption that 50% of the participants would have some level of knowledge, with a 2% margin of error and 95% confidence level. To reach our intended sample size of 1540, we contacted 1722 participants with a response rate of 89.4%.

RESULTS

The expected percentage of public knowledge was 50%; however, the actual percentage revealed by this study was much lower (29.7%). A stepwise multiple logistic regression was used to assess the factors that positively affected the knowledge score regarding TKA. Age [P = 0.016 with OR of 0.47], higher income [P = 0.001 with OR of 0.52] and participants with a positive history of TKA or that have known someone who underwent the surgery [P < 0.001 with OR of 0.15] had a positive impact on the total knowledge score.

CONCLUSIONS

There are still misconceptions among the public in Saudi Arabia concerning TKA, its indications and results. We recommend that doctors use the results of our survey to assess their conversations with their patients, and to determine whether the results of the procedure are adequately clarified.