No benefit of patient-specific instrumentation in TKA on functional and gait outcomes: a randomized clinical trial

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.

The use of virtual reality to assess the bony landmarks at the knee joint - The role of imaging modality and the assessor's experience

BACKGROUND

At present, extended reality technologies such as virtual reality (VR) have gained popularity in orthopedic surgery. The first aim of this study was to assess the precision of VR and other imaging modalities - computed tomography (CT), magnetic resonance imaging (MRI) - to localize bony landmarks near the knee joint. Secondly, the impact of the educational level of the assessor - medical master students, orthopedic residents, and orthopedic surgeons - on the precision with which landmarks near the knee joint could be localized was analyzed.

METHODS

We included a total of 77 participants: 62 medical master students, 10 orthopedic residents, and 5 orthopedic surgeons to analyze three cadaver legs. Every participant localized a series of sixteen bony landmarks on six different imaging modalities (CT, MRI, 3D-CT, 3D-MRI, VR-CT, VR-MRI).

RESULTS

Concerning the imaging modality, the inter- and intra-observer variability were lowest for 3D and VR, higher for MRI (respectively 7.6 mm and 6.9 mm), and highest for CT (respectively 9 mm and 8.7 m).Concerning the educational level of the assessor, inter- and intra-observer variability in VR were lowest for surgeons, (respectively 3.2 mm and 3.6 mm), higher for residents (respectively 5.9 mm and 6.5 mm) and medical students (respectively 5.9 mm and 5.8 mm).

CONCLUSIONS

VR can be considered a reliable imaging technique. Localization of landmarks tends to be more precise in VR and on 3D than on conventional CT and MRI images. Furthermore, orthopedic surgeons localize landmarks more precisely than orthopedic residents and medical students in VR.

Comparison of spatiotemporal, kinematic, and kinetic gait characteristics in total and unicompartmental knee arthroplasty during level walking: A systematic review and meta-analysis

PURPOSE

This meta-analysis was performed to compare the spatiotemporal, kinematic, and kinetic gait characteristics during level walking between total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA).

METHODS

An electronic database literature search was performed to screen clinical trials which were included the studies evaluating not only spatiotemporal, kinematic, and kinetic gait parameters, but also knee range of motion and knee score (Knee Society Score and Oxford Knee Score, i.e., KSS and OKS). The data analysis was performed using statistical software Stata 14.0 and Review Manager 5.4.

RESULTS

Thirteen studies (369 knees) that met the criteria were eventually included in this meta-analysis. The results revealed significant differences between UKA and TKA with regard to walking speed (P = 0.04), stride length (P = 0.02), maximum knee flexion at loading (P = 0.001), the 1st peak of vert-GRF (P = 0.006), the 1st valley of vert-GRF (P = 0.007), knee internal rotational moment (P = 0.04), knee extension (P < 0.00001), and KSS Function score (P = 0.05). In contrast, there were no statistical differences in the remaining spatiotemporal, kinematic, and kinetic gait parameters.

CONCLUSION

Medial UKA design is superior to TKA design with regard to walking speed, stride length, maximum knee flexion at loading, the 1st peak and the 1st valley of vert-GRF, knee internal rotational moment, knee extension, and KSS Function score. And it could provide a stronger basis for physicians to make clinical decisions.

The efficacy and safety of patient-specific instrumentation in primary total knee replacement: a systematic review and meta-analysis

INTRODUCTION

Patient-specific instrumentation (PSI) for primary total knee arthroplasty (TKA) surgery has been shown to increase accuracy of component positioning. However, it is unclear whether this also translates to actual benefits for patients in terms of better outcomes (efficacy) or less complications such as revisions (safety). We therefore systematically reviewed the literature to determine the efficacy and safety of PSI in primary TKA.

METHODS

Randomized controlled trials comparing PSI to non-PSI in primary TKA were included. A random effects model was used with meta-regression in case of heterogeneity.

RESULTS

Forty-three studies were included with a total of 1816 TKA in the PSI group and 1887 TKA in the control group. There were no clinically relevant differences between the PSI-group and non-PSI group regarding all outcomes. There was considerable heterogeneity: meta-regression analyses showed that the year the study was published was an important effect modifier. Early publications tended to show a positive effect for PSI compared to non-PSI TKA, whereas later studies found the opposite.

CONCLUSION

Based on evidence of moderate certainty, our study suggested that there were no clinically relevant differences in efficacy and safety between patients treated with PSI TKA and patients treated with non-PSI TKA.

Functional outcomes in patient specific instrumentation vs. conventional instrumentation for total knee arthroplasty; a systematic review and meta-analysis of prospective studies

Background

Total Knee Arthroplasty (TKA) is an established surgical option for knee osteoarthritis (OA). There are varying perceptions of the most suitable surgical technique for making bone cuts in TKA. Conventional Instrumentation (CI) uses generic cutting guides (extra- and intra-medullary) for TKA; however, patient specific instrumentation (PSI) has become a popular alternative amongst surgeons.

Methods

A literature search of electronic databases Embase, Medline and registry platform portals was conducted on the 16^th May 2021. The search was performed using a predesigned search strategy. Eligible studies were critically appraised for methodological quality. The primary outcome measure was Knee Society Function Score. Functional scores were also collected for the secondary outcome measures: Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Visual Analog Scale (VAS) for pain. Review Manager 5.3 was used for all data synthesis and analysis.

Results

There is no conclusive evidence in the literature to suggest that PSI or CI instrumentation is better for functional outcomes. 23 studies were identified for inclusion in this study. Twenty-two studies (18 randomised controlled trials and 4 prospective studies) were included in the meta analysis, with a total of 2277 total knee arthroplasties. There were 1154 PSI TKA and 1123 CI TKA. The majority of outcomes at 3-months, 6-months and 12 show no statistical difference. There was statistical significance at 24 months in favour of PSI group for KSS function (mean difference 4.36, 95% confidence interval 1.83–6.89). The mean difference did not exceed the MCID of 6.4. KSS knee scores demonstrated statistical significance at 24 months (mean difference 2.37, 95% confidence interval (CI) 0.42—4.31), with a MCID of 5.9. WOMAC scores were found to be statistically significant favouring PSI group at 12 months (mean difference -3.47, 95% confidence interval (CI) -6.57- -0.36) and 24 months (mean difference -0.65, 95% confidence interval (CI) -1.28—-0.03), with high level of bias noted in the studies and a MCID of 10.

Conclusions

This meta-analysis of level 1 and level 2 evidence shows there is no clinical difference when comparing PSI and CI KSS function scores for TKA at definitive post operative time points (3 months, 6 months, 12 months and 24 months). Within the secondary outcomes for this study, there was no clinical difference between PSI and CI for TKA. Although there was no clinical difference between PSI and CI for TKA, there was statistical significance noted at 24 months in favour of PSI compared to CI for TKA when considering KSS function, KSS knee scores and WOMAC scores. Studies included in this meta-analysis were of limited cohort size and prospective studies were prone to methodological bias. The current literature is limited and insufficiently robust to make explicit conclusions and therefore further high-powered robust RCTs are required at specific time points.

Tibiofemoral lift-off and resulting laxity following total knee arthroplasty: Frequency in a series of 906 continuous cases and functional consequences at 4 years' follow-up in a case-control study

BACKGROUND

Tibiofemoral instability is one reason for early revision of total knee arthroplasty. It can be the consequence of tibiofemoral laxity, especially in the coronal plane with tibiofemoral lift-off. But does femoral condyle lift-off on conventional postoperative radiographs suggest the presence of laxity or potential instability? To our knowledge, this question has not yet been answered. This led us to conduct a retrospective study to evaluate (1) the frequency of lift-off on postoperative radiographs, (2) the relationship between lift-off and laxity in the short term and (3) the functional consequences of lift-off.

HYPOTHESIS

Postoperative lift-off is a rare event that is predictive of laxity.

METHODS

We carried out a single-center retrospective study using postoperative radiographs from patients who underwent primary total knee arthroplasty between 2014 and 2016. The sample consisted of 906 patients. Lift-off was defined as a tibiofemoral angle of 3° or more on immediate postoperative radiographs (day 0) that were non-weightbearing and had no stress applied. The functional outcomes were determined in the 17 patients identified as having lift-off who had been operated in the first year (2014) to ensure the follow-up was long enough. These patients were compared to 34 matched control patients who were operated the same year and chosen randomly among patients not having lift-off. The matching ratio was 2 controls to 1 case. Preoperative and surgical data were compiled from each patient's electronic medical record. Patients were evaluated at 4 years postoperatively using the subjective Oxford-48, objective HSS score, IKS score, overall patient satisfaction and stress radiographs of the knee. The cases of lift-off observed in 2014 (n=17) were paired with a control group of patients selected randomly during 2014.

RESULTS

The frequency of the lift-off event was 63/906 or 7%. The frequency was consistent over the three years studied: 7.1% in 2014 (19/269), 6.2% in 2015 (22/354) and 7.8% in 2016 (22/283). There was no significant difference between the two groups (17 with lift-off and 34 without) in the sex, age, body mass index and coronal plane deformity (preoperative HKA angle). At a mean follow-up of 4 years (range 12-49 months), the knees with postoperative lift-off had more laxity (p=0.002), particularly laxity when varus stress was applied (p=0.009). There were no other significant differences in the outcomes.

DISCUSSION

Immediate postoperative lift-off after total knee arthroplasty is not a rare event, with a 7% frequency in our study. While it reveals that laxity is present in the particular compartment, there is no evidence of functional consequences at 4 years' follow-up; however, a long-term assessment is required to verify this finding.

LEVEL OF EVIDENCE

III - case-control study.

Does the use of patient-specific instrumentation improve resource use in the operating room and outcome after total knee arthroplasty?–A multicenter study

Patient-specific instrumentation (PSI) in total knee arthroplasty (TKA) has been introduced to reduce instruments and surgical time and to improve implant alignment. The aim of this study was to compare TKA with patient-specific and conventional instrumentation with regard to the use of resources in the operating room (OR), alignment and patient-reported outcome. A total of 139 TKA with PSI or conventional instrumentation were included in three centers. Economic variables of the surgery (number of instrument trays, setup and cut-sew-time), radiological alignment and patient reported outcomes (VAS Pain Scale, Oxford Knee Score, EQ-5D) were assessed after 6 weeks, 6 and 12 months. There was a significant reduction of instrument trays and of time in the OR in the PSI group. The reduction varied between the centers. With strict reorganization, more than 50% of the instrument trays could be reduced while using PSI. There were no significant differences in cut-sew-time, implant position, leg axis, pain and function. The use of PSI was associated with significantly less OR resources. However, the savings did not compensate the costs for this technology.

Time is Money! Influence on Operating Theater and Sterilization Times of Patient-specific Cutting Guides and Single-use Instrumentation for Total Knee Arthroplasty: A Full Factorial Design of 136 Patients

Background

Patient-specific cutting guides (PSGs) and single-use disposable instrumentation (SUI) have emerged as potential beneficial innovations for total knee arthroplasty. The aim of this study was to evaluate the impact of PSG and SUI for total knee arthroplasty on operating room (OR) and sterilization times.

Methods

A monocentric, prospective, interventional, full factorial design study, including 136 patients, compared patient-specific (PSG, n = 68) to conventional cutting guides (n = 68) and SUI (n = 68) to conventional instrumentation (CVI, n = 68). In the OR, we recorded the number of instrument trays, operating time, and room occupancy time. In the central sterile services department, the total sterilization duration was assessed. The primary outcome was operating time and sterilization duration. Secondary outcomes were difference in the number of trays, Oxford Knee Score, and postoperative mechanical axis.

Results

The median operating time was 80 minutes (Q1-Q3: 73-90) and was significantly increased for SUI compared to that for CVI (+5 minutes, P = .0072). The median sterilization duration was 1261 minutes (Q1-Q3: 934-1603). It was significantly in favor of SUI (936 minutes) over CVI (1565 minutes) (+629 minutes, P < .0001). The total number of instrument trays was 404 for 136 patients: 252 for CVI and 152 for SUI (P < .0001) and 189 for PSG and 215 for conventional cutting guides (P = .0006). There was no significant difference in OKS (P = .86) nor in the postoperative alignment which was between 177° and 183° (75% patients, P = .24).

Conclusions

SUI lowers the number of instrument trays and sterilization duration. PSG is not associated with significant OR or sterilization time reduction. The use of SUI could reduce the risk of noncompliance of instrument trays.

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.

Prosthetic Accuracy Depends on the Design of Patient-Specific Instrumentation: Results of a Retrospective Study Using Three-Dimensional Imaging

To determine accuracy of patient-specific instrumentation (PSI), the preoperative three-dimensional (3D) plan should be superimposed on the postoperative 3D image to compare prosthetic alignment. We aimed to compare prosthetic alignment on a preoperative 3D computed tomography (CT) plan and postoperative 3D-CT image, and evaluate the accuracy of PSI during total knee arthroplasty (TKA). Thirty consecutive knees (30 patients) who underwent TKA using PSI were retrospectively evaluated. The preoperative plan was prepared using 3D CT acquisitions of the hip, knee, and ankle joints. The postoperative 3D CT image obtained 1 week after surgery was superimposed onto the preoperative 3D plan using computer software. Differences in prosthetic alignment between the preoperative and postoperative images were measured using six parameters: coronal, sagittal, and axial alignments of femoral and tibial prostheses. Differences in prosthetic alignment greater than 3 degrees were considered outliers. Two observers performed all measurements. All parameters were repeatedly measured over a 4-week interval. This measurement method's intraobserver and interobserver reliabilities were more than 0.81 (very good). For the femoral and tibial prostheses, absolute differences between the preoperative and postoperative 3D CT images were significantly larger in the sagittal than in the coronal and axial planes (p < 0.001). The outlier rate for the sagittal alignment of femoral and tibial prostheses was significantly higher than that for the alignment of coronal and axial planes (p < 0.001). However, there were no significant differences in the range of motion (ROM) before and after TKA when comparing cases with and without outliers in the sagittal plane. Even though the present study did not reveal any issues with the ROM that depended on the presence of an outlier, accurate verification of prosthetic alignment for individual PSI models may be necessary because the designs, referenced images, and accuracy are different in each model.

The current and possible future role of 3D modelling within oesophagogastric surgery: a scoping review

BACKGROUND

3D reconstruction technology could revolutionise medicine. Within surgery, 3D reconstruction has a growing role in operative planning and procedures, surgical education and training as well as patient engagement. Whilst virtual and 3D printed models are already used in many surgical specialities, oesophagogastric surgery has been slow in their adoption. Therefore, the authors undertook a scoping review to clarify the current and future roles of 3D modelling in oesophagogastric surgery, highlighting gaps in the literature and implications for future research.

METHODS

A scoping review protocol was developed using a comprehensive search strategy based on internationally accepted guidelines and tailored for key databases (MEDLINE, Embase, Elsevier Scopus and ISI Web of Science). This is available through the Open Science Framework (osf.io/ta789) and was published in a peer-reviewed journal. Included studies underwent screening and full text review before inclusion. A thematic analysis was performed using pre-determined overarching themes: (i) surgical training and education, (ii) patient education and engagement, and (iii) operative planning and surgical practice. Where applicable, subthemes were generated.

RESULTS

A total of 56 papers were included. Most research was low-grade with 88% (n = 49) of publications at or below level III evidence. No randomised control trials or systematic reviews were found. Most literature (86%, n = 48) explored 3D reconstruction within operative planning. These were divided into subthemes of pre-operative (77%, n = 43) and intra-operative guidance (9%, n = 5). Few papers reported on surgical training and education (14%, n = 8), and were evenly subcategorised into virtual reality simulation (7%, n = 4) and anatomical teaching (7%, n = 4). No studies utilising 3D modelling for patient engagement and education were found.

CONCLUSION

The use of 3D reconstruction is in its infancy in oesophagogastric surgery. The quality of evidence is low and key themes, such as patient engagement and education, remain unexplored. Without high quality research evaluating the application and benefits of 3D modelling, oesophagogastric surgery may be left behind.

Cementless modular total hip arthroplasty with subtrochanteric transverse shortening osteotomy for high hip dislocations

Background

Performing a total hip arthroplasty for a high hip dislocation is technically demanding and presents several challenges, with appropriate evaluation of the bone morphology of the hip and proper implant selection being critical for successful outcomes.

Objective

The purpose of our study was to evaluate the clinical and radiographic outcomes of cementless modular total hip arthroplasty for the treatment of high hip dislocations with sub-trochanteric transverse shortening osteotomy.

Methods

Sixty-eight hips with a high hip dislocation, were treated using a sub-trochanteric transverse shortening osteotomy and cementless modular total hip arthroplasty, retrospectively reviewed. Hip function was assessed using the Harris hip score, with hip abduction strength evaluated using the Trendelenburg test. Radiographic assessment included the measurement of leg length discrepancy, identification of implant loosening, localization of the hip center, and union at the osteotomy site.

Results

The mean follow-up period was 12.9 (range 5.2–16.8) years. The mean Harris hip score improved from a pre-operative score of 48.6 ± 3.6 to 82.4 ± 4.2 (p < 0.05). The hip was within the true acetabulum in all patients, postoperatively. Osteotomy union was achieved in 67 of the 68 hips (98.5%) in a mean latency of 12.5 ± 0.6 weeks. The mean length of femoral shortening was 66.5 ± 4.5 mm, with a mean pull-down length of the proximal part of 35.5 ± 3.5 mm.

Conclusion

For the treatment of high hip dislocations with satisfactory clinical outcomes, the modular stem offers an adjustable anteversion angle to restore sufficient rotational stability and the transverse osteotomy provides sufficient compression pressure across the osteotomy site to facilitate union.

Trial registration It was a retrospective study and approved by Istanbul Research and Training Hospital institutional Ethics Review Board (772-05/02/2016).

Evaluation of the accuracy of resected bone thickness based on patient-specific instrumentation during total knee arthroplasty

BACKGROUND

In total knee arthroplasty (TKA) using patient-specific instrumentation (PSI), the correlation between the preoperative surgical plan and intraoperative resection size is unclear. The aims of this study were to evaluate whether the computed tomography (CT)-based PSI surgical plan can be executed accurately and to determine the accuracy of bone resection in TKA using PSI.

METHODS

Data of 45 consecutive knees undergoing TKA using CT-based PSI were retrospectively evaluated. The preoperative plan was prepared using three-dimensional CT acquisitions of the hip, knee, and ankle joints. Resected bone thicknesses of the femoral condyle of the distal medial, distal lateral, posterior medial, posterior lateral, and medial and lateral tibial plateaus were measured with a Vernier caliper intraoperatively. Then these respective measurements were compared with those in the preoperative CT-predicted bone resection surgical plan, and the measured thickness of resection was subtracted from the planned resection thickness. Errors were defined as: acceptable, ≤ 1.5 mm; borderline, 1.5-2.5 mm; and outliers,  > 2.5 mm.

RESULTS

Overall, 22 (48.9%) knees had no outliers. There were 20 (44.4%) and 3 (6.7%) knees in which only 1 and 2 resection planes were outliers, respectively. The posterior medial tibial plateau had the lowest proportion of acceptable cuts (44.4%). Posterior femoral resection including the medial and lateral condyles had more outliers (n = 18/90 cuts, 20.0%) (p < 0.001) than the tibial condyles (n = 3/90 cuts, 3.3%) and distal femoral cuts (n = 6/90 cuts, 6.7%). The posterior surface of the femur, where the incidence of outliers was higher, tended to have a higher proportion of undercuts than other surfaces of the femur (> 80%).

CONCLUSIONS

PSI showed only fair-to-moderate accuracy. The cutting guide for the posterior femur was less accurate than that for the tibia and distal femur. Specific attention is required when cutting the posterior femur. The PSI design needs to be improved to reduce errors.

Minimum Five Years Follow-Up of Total Knee Arthroplasty Using Morphometric Implants in Patients With Osteoarthritis

BACKGROUND

The use of morphometric implants in total knee arthroplasty (TKA) has shown better early clinical outcomes compared to conventional implants. The primary objective of this study is to evaluate the functional outcome and the implant survivorship of a morphometric TKA at a minimum of 5 years of follow-up.

METHODS

From May 2012 to June 2015, all patients undergoing primary TKA with a single design of morphometric posterior-stabilized prosthesis (Persona; Zimmer) in a prospective observational single-center study were evaluated. The Knee Society Scoring System (KSS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were completed preoperatively, 1, 3, and 5 years postoperatively. Kaplan-Meier was used to calculate survivorship of the implants. The average follow-up was 75 months.

RESULTS

In total, 237 TKAs were performed in 235 patients with a mean age of 73 years (49-90). The KSS Knee Score increased from 44.7 (13-64) preoperatively to 93.6 (71-100), the KSS Function Score from 45.8 (17-69) to 92.2 (51-98), and the KSS Satisfaction Score from 26.6 (16-51) to 41 (35-55) at 5 years of follow-up. Similarly, for the KOOS score, a significant improvement of all the subscales was observed at 5 years of follow-up. Implant survival without reoperation at 5 years of follow up was 98.72% (95% confidence interval 0.95-1.00).

CONCLUSION

This is the first study demonstrating that significant improvements of the functional scores with good survivorship can be achieved at a minimum of 5 years of follow-up with TKA using morphometric implants.

Mid-term functional outcomes of patient-specific versus conventional instrumentation total knee arthroplasty: a prospective study

INTRODUCTION

Patient-specific instrumentation (PSI) utilizes three-dimensional imaging to produce total knee arthroplasty cutting jigs which matches patient's native anatomy. However, there are limited mid- to long-term studies examining its clinical efficacy. The aim of this study was to compare functional outcomes of PSI surgery versus conventional TKA surgery at 5-year follow-up.

MATERIALS AND METHODS

Sixty patients were prospectively recruited into either the MRI-based PSI or conventional TKA group. Functional outcomes were assessed using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS), while quality of life was evaluated with the Physical Component Score (PCS) and Mental Component Score (MCS) of Short-Form 36 and compared between the two groups at 5-year follow-up.

RESULTS

Although the PCS was 7 ± 3 points better in the PSI group preoperatively (p = 0.017), it became 5 ± 2 points worse than the conventional group at 5-year follow-up (p = 0.025). As compared to the PSI group, the conventional group showed a significantly greater improvement in PCS at 5 years as compared to before surgery (p = 0.003). There were no significant differences in KSFS, KSKS, OKS or MCS between the two groups.

CONCLUSIONS

PSI TKA did not result in improved functional outcomes or better quality of life when compared to conventional TKA. The additional costs and waiting time associated with PSI are not justifiable and therefore not recommended as an alternative to conventional TKA.

LEVEL OF EVIDENCE

II.

Matching walking speed of controls affects identification of gait deviations in patients with a total knee replacement

BACKGROUND

The assessment of functional recovery of patients after a total knee replacement includes the quantification of gait deviations. Comparisons to comfortable gait of healthy controls may incorrectly suggest biomechanical gait deviations, since the usually lower walking speed of patients already causes biomechanical differences. Moreover, taking peak values as parameter might not be sensitive to actual differences. Therefore, this study investigates the effect of matching walking speed and full-waveform versus discrete analyses.

METHODS

Gait biomechanics of 25 knee replacement patients were compared to 22 controls in two ways: uncorrected and corrected for walking speed employing principal component analyses, to reconstruct control gait biomechanics at walking speeds matched to the patients. Ankle, knee and hip kinematics and kinetics were compared over the full gait cycle using statistical parametric mapping against using peak values.

FINDINGS

All joint kinematics and kinetics gait data were impacted by applying walking speed correction, especially the kinetics of the knee. The lower control walking speeds used for reference generally reduced the magnitude of differences between patient and control gait, however some were enlarged. Full-waveform analysis identified greater deviating gait cycle regions beyond the peaks, but did not make peak value analyses redundant.

INTERPRETATION

Matching walking speed of controls affects identification of gait deviations in patients with a total knee replacement, reducing deviations confounded by walking speed and revealing hidden gait deviations related to possible compensations. Full-waveform analysis should be used along peak values for a comprehensive quantification of differences in gait biomechanics.

New Technologies in Knee Arthroplasty: Current Concepts

Total knee arthroplasty (TKA) is an effective treatment for severe osteoarthritis. Despite good survival rates, up to 20% of TKA patients remain dissatisfied. Recently, promising new technologies have been developed in knee arthroplasty, and could improve the functional outcomes. The aim of this paper was to present some new technologies in TKA, their current concepts, their advantages, and limitations. The patient-specific instrumentations can allow an improvement of implant positioning and limb alignment, but no difference is found for functional outcomes. The customized implants are conceived to reproduce the native knee anatomy and to reproduce its biomechanics. The sensors have to aim to give objective data on ligaments balancing during TKA. Few studies are published on the results at mid-term of these two devices currently. The accelerometers are smart tools developed to improve the TKA alignment. Their benefits remain yet controversial. The robotic-assisted systems allow an accurate and reproducible bone preparation due to a robotic interface, with a 3D surgical planning, based on preoperative 3D imaging or not. This promising system, nevertheless, has some limits. The new technologies in TKA are very attractive and have constantly evolved. Nevertheless, some limitations persist and could be improved by artificial intelligence and predictive modeling.

Planning on CT-Based 3D Virtual Models Can Accurately Predict the Component Size for Total Knee Arthroplasty

The ability to predict accurate sizing of the implant components for total knee arthroplasty surgery can have several benefits in the operating room, in terms of simplifying the workflow and reducing the number of required instrument trays. Planning on a three-dimensional (3D) virtual model can be used to predict size. The aim of this study was to quantify the accuracy of the surgeon-validated plan prediction on a computed tomography (CT)-based system. The clinical records of 336 cases (267 patients), operated using a CT-based patient-specific instrumentation, have been reviewed for the size of implanted components. Preoperative default planning (according to the preferences of the surgeon) and approved planning have been compared with the size of implanted components for both the femur and tibia. The prosthesis size, preplanned by the manufacturers, was modified by the surgeon during the validation process in 0.9% of cases for the femoral component and in 2.7% of cases for the tibial component. The prosthesis size, preplanned by the surgeon after the validation process, was used in 95.8% for the femur and 92.6% for the tibia. Concordance on the size of the surgeon-validated plan and the finally implanted size was perfect for both, the femoral (κ  =  0.951; 95% confidence interval [CI]: 0.92-0.98) and the tibial component (κ  =  0.902; 95% CI: 0.86-0.94). The most frequent change of size (51%) was an increase by one size of the planned tibial component. Planning of knee arthroplasty surgery on a 3D virtual, CT-based model is useful to surgeons to help predict the size of the implants to be used in surgery. The system we have used can accurately predict the component size for both the femur and tibia. This study reflects a study of level III evidence.

Core Outcome Measurement Instruments for Clinical Trials of Total Knee Arthroplasty: A Systematic Review

(1) Background: We have updated knowledge of the psychometric qualities of patient-reported outcome measures and, for the first time, systematically reviewed and compared the psychometric qualities of physical tests for patients with knee osteoarthritis who are undergoing total knee arthroplasty. This work was conducted to facilitate the choice of the most appropriate instruments to use in studies and clinical practice. (2) Methods: A search of medical databases up to December 2019 identified the studies and thus the instruments used. The quality of the measurement properties was assessed by the Bot et al. criteria. (3) Results: We identified 20 studies involving 25 instruments. Half of the instruments were questionnaires (n = 13). Among the condition-specific instruments, the Oxford knee score, Knee injury and Osteoarthritis Outcomes Score, and the Western Ontario and McMaster Universities Osteoarthritis index had the highest overall scores. Concerning generic tools, the Medical Outcomes Study Short-Form 36 (SF-36) or SF-12 obtained the highest overall score. For patient-specific tools, the Hospital Anxiety and Depression Scale ranked the highest. Some physical tests seemed robust in psychometric properties: 6-min Walk Test, five times Sit-To-Stand test, Timed Up and Go test strength testing of knee flexor/extensor by isometric or isokinetic dynamometer and Pressure Pain Threshold. (4) Conclusion: To make stronger recommendations, key areas such as reproducibility, responsiveness to clinical change, and minimal important change still need more rigorous evaluations. Some promising physical tests (e.g., actimetry) lack validation and require rigorous studies to be used as a core set of outcomes in future studies.

Design improvement in patient-specific instrumentation for total knee arthroplasty improved the accuracy of the tibial prosthetic alignment in the coronal and axial planes

PURPOSE

The accuracy of patient-specific instrumentation (PSI) in total knee arthroplasty (TKA) is still controversial, especially in the tibial prosthesis. It was hypothesized that the design modification of PSI improved the tibial prosthetic alignment and reduced the associated complications. The aim of this study was to compare the accuracy of a conventional PSI with that of a newly designed PSI for total knee arthroplasty (TKA) using a new three-dimensional (3D) measurement method.

METHODS

Thirty TKAs each using the conventional and newly designed PSIs were studied. The postoperative 3D-computed tomography (3D CT) image was superimposed on the preoperative 3D CT plan. The absolute differences in the tibial prosthetic alignment between the preoperative and postoperative 3D CT images were directly measured in the coronal, sagittal, and axial planes. Knees in which the difference in the prosthetic alignment was > 3° were considered deviations.

RESULTS

The new PSI showed less mean absolute differences and lower rate of deviations than the conventional PSI in the coronal and axial planes (p = 0.045 and p = 0.004, respectively). The deviations (> 3°) of the tibial prosthesis using the conventional PSI were 27, 30, and 63% and of those using the new PSI were 0, 20, and 20% in the coronal, sagittal, and axial planes, respectively.

CONCLUSIONS

This is the first report to evaluate the effect of improvement in PSI design on the postoperative alignment using 3D method, and it clearly showed that the modification significantly improved the accuracy of alignment and reduced the deviations.

LEVEL OF EVIDENCE

Therapeutic study, case-control study, Level III.

Patient-Specific or Conventional Instrumentations: A Meta-analysis of Randomized Controlled Trials

Objective

To conduct a meta-analysis of randomized controlled trials (RCTs) to compare knee arthroplasty with patient-specific instrumentation (PSI) with the conventional instrumentation (CI).

Methods

RCTs were selected in PubMed and Embase from 2012 to 2018. Key data extracted included malalignment of mechanical axis, blood loss, surgical time, Oxford Knee Score (OKS), Knee Society Score (KSS), length of stay, and complications. Subgroup analysis was also performed regarding different PSI systems and different image processing methods.

Results

29 RCTs with 2487 knees were eligible for the meta-analysis. Results showed that PSI did not improve the alignment of the mechanical axis compared with CI, but MRI-based PSI and Visionaire-specific PSI decrease the risk of malalignment significantly (P = 0.04 and P = 0.04 and P = 0.04 and P = 0.04 and P = 0.04 and

Conclusion

PSI reduced the blood loss and improved KSS. MRI-based PSI reduced operative time and risk of malalignment of mechanical axis compared with CT-based PSI. Moreover, Visionaire-specific PSI achieves better alignment result of the mechanical axis than other systems.

Improved mediolateral load distribution without adverse laxity pattern in robot-assisted knee arthroplasty compared to a standard manual measured resection technique

PURPOSE

Robot-assisted total knee arthroplasty (rTKA) remains in its infancy, is expensive but offers the promise of improved kinematic performance through precise bone cuts, with minimal soft tissue disruption, based on pre-resection soft tissue behaviour. This cadaveric study examined load transfer, soft tissue performance and radiographic indices for conventional (sTKA) versus rTKA. The null hypothesis was there would be no difference between the two modes of implantation.

METHODS

Whole (ten) cadaveric limbs were randomised to receive either robotic (rTKA, N = 5) or conventional measured resection (sTKA, N = 5) knee arthroplasty. Laxity patterns were established using validated fixed sensors (Verasense) with manual maximum displacement for six degrees of freedom. Tibiofemoral load and contact points were determined dynamically using remote sensor technology for medial and lateral compartments through a functional arc of motion (0-110 degrees of motion). Final component position was assessed using pre- and post-implantation CT.

RESULTS

No significant intergroup differences for laxity were found (n.s.). The rTKA group exhibited consistently balanced mediolateral load throughout the full arc with significantly reduced overall total load across the joint (for distinct points of measurement, p < 0.05). Despite using flexion-extension and mediolateral gap balancing with measured resection, the sTKA group failed to achieve balance in at least three points of the flexion arc. Post-operative CT confirmed satisfactory component alignment with no significant differences for positioning between the two groups.

CONCLUSION

This work found improved load sharing for rTKA when compared to conventional surgery for same donor knees. Laxity and CT determined final component positioning was not significantly different. The work supports the contention that robot-assisted TKA delivers improved tibiofemoral load sharing in time zero studies under defined conditions but such offers the promise of improved clinical performance and reduced implant wear.

Quantitative evaluation of gait features after total knee arthroplasty: Comparison with age and sex-matched controls

BACKGROUND

Gait function after total knee arthroplasty (TKA) is suboptimal. However, quantified analysis with comparing a control group is lacking.

RESEARCH QUESTION

The aims of this study were 1) to compare the gait before and after TKA and 2) to compare postoperative gait to that of an age-sex matched control group.

METHODS

This study consisted of 46 female and 38 male patients with end-stage knee osteoarthritis who underwent bilateral TKA, and 84 age- and sex-matched controls without knee pain and osteoarthritis. Seven gait parameters, including lower extremity alignment, knee adduction moment (KAM), knee flexion angle, external knee flexion moment, hip adduction angle, external hip adduction moment, and the varus-valgus arc during the stance phase, were collected using a commercial opto-electric gait analysis system. Principal component analysis was used for data processing and the standardized mean differences (SMDs) of the principal component scores were compared.

RESULTS

The most significant gait change after TKA was the alignment (SMD 1.62, p < 0.001). The average stance phase alignment changed from varus 7.3° to valgus 0.5°. The second significant change was a decrease of the KAM (SMD 1.08, p < 0.001). These two features were closely correlated (r = 0.644, p < 0.001). The gait feature that differed most from the controls was the varus-valgus arc during the stance phase (SMD 1.68, p < 0.001), which was constrained by 31% after TKA (p < 0.001) and was only 37% compared to the controls (p < 0.001).

SIGNIFICANCE

Improvement in gait after TKA was obtained through alignment correction. However, TKA significantly constrained coronal knee motion. TKA improved gait suboptimally; the gait was significantly different from that of controls.

Total knee arthroplasty using patient-specific instrumentation for osteoarthritis of the knee: a meta-analysis

BACKGROUND

Total knee arthroplasty using patient-specific instrumentation (TKA-PSI), which are disposable cutting block guides generated to fit each patient's 3-dimensional knee anatomy, has been developed to treat patients with end-stage osteoarthritis of the knee. Surrogate markers such as radiographic malalignment have been well investigated, however, patient-important outcomes are not well examined to elucidate the efficacy of TKA-PSI. The aim of this review is to determine if TKA-PSI improves patient-reported outcome measures (PROM), surgery time, blood loss, transfusion and complications (e.g. surgical site infection, deep venous thrombosis, and revision TKA).

METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and ongoing clinical trials. For PROMs, surgery time, blood loss, and transfusion rate, we included randomized controlled trials (RCT) comparing TKA-PSI and standard TKA to treat osteoarthritis of the knee. For complications, we also included non-randomized comparative studies (non-RCT).

RESULTS

This review includes 38 studies, 24 of which were RCT and 14 of which were non-RCT. These included a total of 3487 patients. The predominant population in the included studies highly reflected the general population, with 62% being female, aged over 60 and having end-stage osteoarthritis of the knee. TKA-PSI did not improve PROMs as compared to standard TKA for less than 1-year (mean difference 0.48, 95% confidence interval (CI) -1.92-0.97 in the Oxford knee score, mean 3-month follow-up) and for 1-year or more (mean difference 0.25, 95%CI - 4.39-4.89 in the WOMAC score, mean 29-month follow-up). TKA-PSI did not reduce surgery time (mean difference - 3.09 min, 95%CI -6.73-0.55). TKA-PSI decreased blood loss with a small effect size corresponding to a 0.4 g/dl hemoglobin decrease (95%CI 0.18-0.88), but did not decrease transfusion rate (risk difference - 0.04, 95%CI -0.09-0.01). TKA-PSI did not reduce complication rates (risk difference 0.00, 95%CI - 0.01-0.01 in the composite outcome).

CONCLUSIONS

TKA-PSI does not improve patient-reported outcome measures, surgery time, and complication rates as compared to standard TKA. TKA-PSI decreases blood loss with a small effect, which is not enough to reduce transfusion rate.

A randomized controlled trial of tibial component migration with kinematic alignment using patient-specific instrumentation versus mechanical alignment using computer-assisted surgery in total knee arthroplasty

AIMS

Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) versus components placed using computer-assisted surgery targeting neutral mechanical alignment (MA+CAS). Tibial component migration measured by radiostereometric analysis was the primary outcome measure (compared longitudinally between groups and to published acceptable thresholds). Secondary outcome measures were inducible displacement after one year and patient-reported outcome measures (PROMS) over two years. The secondary objective was to assess the relationship between alignment and both tibial component migration and inducible displacement.

PATIENTS AND METHODS

A total of 47 patients due to undergo TKA were randomized to KA+PSI (n = 24) or MA+CAS (n = 23). In the KA+PSI group, there were 16 female and eight male patients with a mean age of 64 years (sd 8). In the MA+CAS group, there were 17 female and six male patients with a mean age of 63 years (sd 7). Surgery was performed using cemented, cruciate-retaining Triathlon total knees with patellar resurfacing, and patients were followed up for two years. The effect of alignment on tibial component migration and inducible displacement was analyzed irrespective of study group.

RESULTS

There was no difference over two years in longitudinal migration of the tibial component between the KA+PSI and MA+CAS groups (reaching median maximum total point motion migration at two years of 0.40 mm for the KA+PSI group and 0.37 mm for the MA+CAS group, p = 0.82; p = 0.68 adjusted for age, sex, and body mass index (BMI) for all follow-ups). Both groups had mean migrations below acceptable thresholds. There was no difference in inducible displacement (p = 0.34) or PROMS (p = 0.61 for the Oxford Knee Score) between groups. There was no correlation between alignment and tibial component migration or alignment and inducible displacement. These findings support non-neutral alignment as a viable option with this component, with no evidence that it compromises fixation.

CONCLUSION

Kinematic alignment using patient-specific instrumentation in TKA was associated with acceptable tibial component migration, indicating stable fixation. These results are supportive of future investigations of kinematic alignment. Cite this article: Bone Joint J 2019;101-B:929-940.

Influence of Diabetes Mellitus on the Recovery Trajectories of Function, Strength, and Self-Report Measures After Total Knee Arthroplasty

OBJECTIVE

As the proportion of individuals with diabetes mellitus (DM) in the aging population and the number of total knee arthroplasties (TKAs) both continue to grow, understanding the outcomes for these patient populations is critical. The purpose of this study was to determine whether patients with and without DM differed in the recovery of 3 physical performance measures during the first 90 days following a TKA.

METHODS

Data collected at ATI Physical Therapy from 169 patients (37 with DM, and 132 without) were available. Physical performance measures included the 4-meter walk test, the 30-second sit-to-stand test (30STS), and the timed-up-and-go test (TUG). A mixed-effects model was performed to determine differences in the rate of recovery and 90-day postoperative scores for all measures.

RESULTS

Both groups had similar baseline values for all measures. Patients with DM demonstrated a slower rate of recovery for the 4-meter walk test, and worse scores for the 4-meter walk test, 30STS, and TUG at the end of 90 days when accounting for significant covariates.

CONCLUSION

Our findings show a negative relationship between the presence of DM and the recovery trajectories of all physical performance measures. Clinicians should closely monitor patients with DM, knowing that they are at higher risk for sustained functional deficits and early complications.

Patient-specific instrumentation in total knee arthroplasty

INTRODUCTION

Total knee arthroplasty (TKA) is one of the most commonly performed orthopedic procedures. During the past decade, patient-specific instrumentation (PSI) has been commercially introduced in order to simplify and make TKA surgery more effective, precise and efficient than conventional mechanical instrumentation (CI) and computer-assisted surgery (CAS). Nevertheless, there are critical arguments against PSI for routine use. The aim of the current manuscript is to describe advantages and limitations of PSI for primary TKA.

AREAS COVERED

By means of a description of the available literature different aspects are discussed (accuracy, clinical and functional outcomes, operative time, blood loss, efficiency and costs).

EXPERT OPINION

Most publications do not claim a significant increase in PSI accuracy over CI, but they also do not postulate PSIs accuracy is worse either. Regarding clinical aspects, PSI did not appear to give any advantage over standard techniques although, equally, it did not appear to show any disadvantages. PSI seems to reduce operative time, could reduce perioperative blood loss and provides logistical benefits in the operation room. Further studies will be required to more thoroughly assess all the advantages and disadvantages of this promising technology as an alternative to CI and CAS.

Health costs and efficiencies of patient-specific and single-use instrumentation in total knee arthroplasty: a randomised controlled trial

Aim

To investigate whether patient-specific instrumentation (PSI) and single-use instrumentation (SUI) improve operating room efficiency in terms of time and cost to the healthcare provider over conventional/reusable instrumentation (CVR) when performing total knee arthroplasty (TKA).

Patients and methods

Patients requiring TKA were randomised into one of four surgical groups: CVR, CVS (conventional/SUI), PSR (PSI/reusable) and PSS (PSI/SUI). All surgical procedures were video recorded to determine specific surgical time intervals. Other variables reported included the number of instrument trays used, missing equipment, direct instrument costs and the weight of the instruments the staff had to handle. Oxford Knee Score (OKS), estimated blood loss and lengths of hospital stay were also recorded as markers of patient experience.

Results

PSR was significantly quicker in all the recorded time intervals, used less trays, experienced less missing equipment and resulted in lower blood loss and shorter hospital stays. SUI reported significantly slower operating room times and resulted in higher blood loss, but SUI was 88% lighter and 20% cheaper on average when compared with their reusable counterparts. Despite the economic advantages of PSI and SUI, the patients who reported greatest improvements in OKS were those allocated to the CVR group, but no clinically meaningful difference in OKS was found at any time point.

Conclusions

PSI and SUI for TKA have the potential of reducing operating room times over conventional, reusable sets. This reduction will benefit theatre personnel ergonomically, while presenting the healthcare provider with potential cost-saving benefits in terms of reduced sterilisation costs and surgical times.

The choice of the femoral center of rotation affects material loss in total knee replacement wear testing - A parametric finite element study of ISO 14243-3

A leading cause of long-term failure of total knee replacements (TKRs) is osteolysis caused by polyethylene wear particles. The current gold standard for preclinical wear testing of TKRs is mechanical knee simulators. The definition of the femoral center of flexion-extension rotation (CoR) has been identified as one possible source of variability within TKR wear tests, since the femoral curvature varies from distal to posterior. The magnitude of the influence on wear due to changes in location of femoral CoR has not been investigated in depth. During this study, a computational framework utilizing finite element analysis for modelling wear of TKRs was developed and used to investigate the influence of the location of femoral CoR on TKR polyethylene wear during standardized displacement controlled testing (ISO 14243-3:2014). The study was carried out using a 40-point Latin Hypercube Design of Experiments approach. Volumetric wear was highly correlated to femoral CoR in both the superior/inferior and anterior/posterior directions, with a stronger relationship in the superior/inferior direction. In addition, wear scars showing linear penetration were examined, with large differences in simulations at the extreme ends of the sampling region. In this study, it was found that variations in the location of the femoral center of rotation can represent a large source of variability in the preclinical testing and evaluation of the wear performance of total knee replacements. This study represents the first attempt at quantifying the effect on wear of different femoral center of rotations across a large sampling space.

Computer navigation for total knee arthroplasty achieves better postoperative alignment compared to conventional and patient-specific instrumentation in a low-volume setting

BACKGROUND

Procedure volume is an important determinant of total knee arthroplasty (TKA) outcomes. We aimed to determine whether computer navigation or patient-specific instrumentation (PSI) would improve postoperative alignment in a low-volume setting.

HYPOTHESIS

PSI for TKA achieves better limb and implant alignment compared to conventional TKA and to computer navigated TKA.

MATERIALS AND METHODS

This is a retrospective cohort study of 385 primary TKAs (Women=59%. Mean age=67years. Mean BMI=30.1kg/m²), which were performed using conventional instrumentation (n=117; 30%), computer navigation (n=209; 54%), or patient-specific instrumentation (n=59; 15%) in a low-volume center (<50 TKAs/year). The risk of postoperative leg and implant mechanical alignment outliers in the coronal plane (>3° from neutral), average alignment and operation time were assessed.

RESULTS

The risk of postoperative mechanical alignment outliers (>3°) was reduced by 89% in the navigated group (4% outliers) compared to the conventional group (35%) (RR=0.11; p<0.0001). No significant improvement was observed in the PSI group (27%) (RR=0.91; p=0.772). The risk of postoperative femoral component coronal alignment outliers was reduced by 63% in the navigated group (11%) compared to the conventional group (31%) (RR=0.37; p=0.018). No significant reduction in outliers was observed in the PSI group (32%) (RR=1.08; p=0.816). There was a reduction in the risk of tibial component coronal malalignment of 66% in the navigated group (5%) compared to the conventional group (13%) (RR=0.33; p=0.070). There was a two-fold increase in the risk of tibial component alignment outliers in the PSI group (29%) (RR=1.94; p=0.110).

DISCUSSION

Computer navigation improved postoperative alignment in TKA. No evidence of improved alignment was seen with patient-specific instrumentation. The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data.

TYPE OF STUDY

Retrospective cohort study. Level IV.

Morphometric Tibial Implant Decreases Posterior Overhang Rate and Improves Clinical Outcomes: Results of a Prospective, Matched Controlled Study

BACKGROUND

Tibial implant's positioning in total knee arthroplasty (TKA) requires a compromise between implant's rotation and bone coverage. We hypothesized that morphometric tibial trays (MTTs) would improve implant positioning and clinical outcomes as compared with symmetrical tibial trays.

METHODS

Thirty-three patients were included prospectively according to the following criteria: age from 18 to 85 years, body mass index <35 kg/m², and posterostabilized cemented TKA performed for primary arthritis. Patients were matched for age, gender, body mass index, and preoperative international knee society (IKS) scoring system and Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, in a 1:1 fashion with patients from a prospectively collected database receiving a symmetrical tibial tray TKA. Tibial implant's rotation, bone coverage, and the percentage of patients with a posterior overhang (PO) >3 mm were assessed using computerized tomography. The IKS and the KOOS were compared at 3-year follow-up.

RESULTS

Bone coverage (90% vs 88%, P = .07) and rotation (mean difference 0.7 ± 3°; P = .69) were not different between the 2 groups. The percentage of patient with a PO was lower in the morphologic group (2/33 vs 14/33, P = .01, odds ratio = 10.3 [2.12-50.24]). Functional scores were superior in the morphometric group: IKS (mean difference 20 ± 21 points; P = .0005), mainly due to a difference in the IKS pain subscore (mean difference 11 ± 15 points; P = .0002). According to the multivariate analysis, an MTT had a positive, independent effect on IKS pain (P = .006) and KOOS pain subscores (P = .03) at the last follow-up.

CONCLUSION

The use of an MTT in TKA did not modify the tibial implant position in the axial plane; however, it decreased implant's posterior overhang and improved functional scores. The clinical improvement was mainly found on pain scores.

Accuracy of Coronal Plane Mechanical Alignment in a Customized, Individually Made Total Knee Replacement with Patient-Specific Instrumentation

The objective of this study was to evaluate the accuracy of a customized individually made total knee implant used in conjunction with patient-specific cutting guides in restoring coronal plane mechanical axis alignment using computer-assisted surgery (CAS). A consecutive series of 63 total knee arthroplasty (TKA) patients were prospectively measured with intraoperative CAS. The patient-specific instruments and implants were created utilizing a preoperative CT scan. CAS system was used for all patients, to determine mechanical alignment. Bone cuts were made using the patient-specific instruments. Both bone cuts and final coronal mechanical alignment were recorded utilizing the navigation system for the assessment.The patient-specific instruments and implants provided perfect neutral coronal mechanical alignment (0°) in 53 patients. The remaining 10 patients had a postoperative alignment within ± 2° of neutral. The average preoperative deformity was 5.57° versus 0.18° postoperatively (p < 0.0001). The mean correction angle was 5.68°. No patients had postoperative extension deficits as measured with CAS (7.50° pre-op for 40/63 patients). Customized, individually made total knee implant with patient-specific cutting jigs showed results that are comparable to those of CAS systems in this study. This technology restores the neutral coronal mechanical axis very accurately, while offering unique benefits such as improved implant fit and restoration of the patient's J-curves, which require further investigation.

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.

Comparison of long-term clinical outcomes after bilateral mobile-bearing total knee arthroplasties using PCL-retaining and PCL-substituting implants in the same patients

PURPOSE

Whether the posterior cruciate ligament (PCL) should be retained or substituted in total knee arthroplasty (TKA) remains an issue of concern. The purpose of this study was to perform within-patient comparisons of mid- and long-term clinical outcomes after mobile-bearing TKA using PCL-retaining (PCLR) and PCL-substituting (PCLS) implant designs.

METHODS

Clinical outcomes were assessed in thirty-eight patients (76 knees) who underwent bilateral scheduled staged TKA with a PCLR design on one side and a PCLS design on the other. Median follow-up periods were 118 months (range 60-211) and 114 months (62-198) in knees with PCLR and PCLS implants, respectively. The preoperative diagnosis for all patients was osteoarthritis. The postoperative clinical results of mobile-bearing TKAs using PCLR and PCLS implant designs were evaluated.

RESULTS

The postoperative Hospital for Special Surgery and the new Knee Society Knee Scoring System scores revealed no differences between PCLR and PCLS implant designs. Postoperative flexion and extension also did not differ between designs. Postoperative median femorotibial alignment was 4° for PCLR and 5° for PCLS implants, respectively; this difference was not significant. Six of the knees with PCLR and three of the knees with PCLS implants had radiolucent lines around the tibial prostheses; these were less than 1 mm and nonprogressive.

CONCLUSIONS

Clinically good results were obtained at approximately 10 years after mobile-bearing TKA using both PCLR and PCLS implant designs bilaterally in the same patients. These results provide conclusive evidence that equivalent clinical results can be obtained with either implant design.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

Alignment options for total knee arthroplasty: A systematic review

In spite of improvements in implant designs and surgical precision, functional outcomes of mechanically aligned total knee arthroplasty (MA TKA) have plateaued. This suggests probable technical intrinsic limitations that few alternate more anatomical recently promoted surgical techniques are trying to solve. This review aims at (1) classifying the different options to frontally align TKA implants, (2) at comparing their safety and efficacy with the one from MA TKAs, therefore answering the following questions: does alternative techniques to position TKA improve functional outcomes of TKA (question 1)? Is there any pathoanatomy not suitable for kinematic implantation of a TKA (question 2)? A systematic review of the existing literature utilizing PubMed and Google Scholar search engines was performed in February 2017. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 569 reports, of which 13 met our eligibility criteria. Four alternative techniques to position a TKA are challenging the traditional MA technique: anatomic (AA), adjusted mechanical (aMA), kinematic (KA), and restricted kinematic (rKA) alignment techniques. Regarding osteoarthritic patients with slight to mid constitutional knee frontal deformity, the KA technique enables a faster recovery and generally generates higher functional TKA outcomes than the MA technique. Kinematic alignment for TKA is a new attractive technique for TKA at early to mid-term, but need longer follow-up in order to assess its true value. It is probable that some forms of pathoanatomy might affect longer-term clinical outcomes of KA TKA and make the rKA technique or additional surgical corrections (realignment osteotomy, retinacular ligament reconstruction etc.) relevant for this sub-group of patients. Longer follow-up is needed to define the best indication of each alternative surgical technique for TKA. Level I for question 1 (systematic review of Level I studies), level 4 for question 2.

Outcomes following total knee arthroplasty with CT-based patient-specific instrumentation

PURPOSE

A 24-month prospective follow-up study was carried out to compare perioperative clinical outcomes, radiographic limb alignment, component positioning, as well as functional outcomes following total knee arthroplasty (TKA) between patient-specific instrumentation (PSI) and conventional instrumentation (CI).

METHODS

Ninety consecutive patients, satisfying the inclusion and exclusion criteria, were scheduled to undergo TKA with either PSI or CI. A CT-based PSI was used in this study, and a senior surgeon performed all surgeries. Patients were clinically and functionally assessed preoperatively, 6 and 24 months post-operatively. Perioperative outcomes were also analysed, including operating time, haemoglobin loss, the need for blood transfusion, length of hospitalisation, and radiographic features.

RESULTS

At 24-month follow-up, clinical and functional outcomes were comparable between the two groups. PSI performed no better than CI in restoring lower limb mechanical alignment or improving component positioning. There were no differences in operating time, haemoglobin loss, transfusion rate, or length of hospitalisation between PSI and CI.

CONCLUSION

No significant clinical benefit could be demonstrated in using PSI over CI after 24 months, and routine use of PSI is not recommended in non-complicated TKA.

LEVEL OF EVIDENCE

II.

Efficacy of Patient-Specific Instruments in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Patient-specific instrumentation (PSI) was introduced with the aim of making the procedure of total knee arthroplasty more accurate and efficient. The purpose of this study was to compare PSI and standard instrumentation in total knee arthroplasty with regard to radiographic and clinical outcomes as well as operative time and blood loss.

METHODS

A meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. PubMed and Embase were searched from 2011 through 2015. We included randomized controlled trials and cohort studies that reported the effect of PSI on the aforementioned outcomes. The primary end point was deviation from the mechanical axis by >3°. Random and fixed-effect models were used for analysis.

RESULTS

A total of 44 studies, which included 2,866 knees that underwent surgery with PSI and 2,956 knees that underwent surgery with standard instrumentation, were evaluated. The risk of mechanical axis malalignment was significantly lower for PSI, with a pooled relative risk of 0.79 (p = 0.013). The risk of tibial sagittal-plane malalignment was higher for PSI than for standard instrumentation (relative risk = 1.32, p = 0.001), whereas the risk of femoral coronal-plane malalignment was significantly lower (relative risk = 0.74, p = 0.043). The risk of tibial coronal-plane malalignment was significantly higher for PSI only when employing fixed-effect meta-analysis (relative risk = 1.33, p = 0.042). Minor reductions in total operative time (-4.4 minutes, p = 0.002) and blood loss (-37.9 mL, p = 0.015) were noted for PSI.

CONCLUSIONS

PSI improves the accuracy of femoral component alignment and global mechanical alignment, but at the cost of an increased risk of outliers for the tibial component alignment. The impact of the increased probability of tibial component malalignment on implant longevity remains to be determined. Meta-analyses indicated significant differences with regard to operative time and blood loss in favor of PSI. However, these differences were minimal and, by themselves, not a substantial justification for routine use of the technology.

LEVEL OF EVIDENCE

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

Does Patient-Specific Instrumentations Improve Short-Term Functional Outcomes After Total Knee Arthroplasty? A Systematic Review and Meta-Analysis

BACKGROUND

Patient-specific instrumentation (PSI) has been recently introduced in knee arthroplasty. There is no strong evidence from meta-analysis on comparison of functional outcomes between PSI and conventional instrumentation.

METHODS

Literature search of electronic databases PubMed, MEDLINE, and Cochrane Library for published randomized controlled trials was undertaken. Search was done using a predesigned search strategy. Eligible studies were critically appraised for the methodological quality using Cochrane Collaboration's tool. Functional scores used for meta-analysis were Knee Society Knee Score, Knee Society Function Scores, Oxford Knee Score, Western Ontario and McMaster Universities Arthritis Index, and Visual Analogue Scale score for pain (0-10 scale).

RESULTS

Five randomized controlled trials involving 379 total knee arthroplasties were eligible to be included in the meta-analysis. No significant improvement in short-term functional outcomes was seen after using PSI compared to the control group in terms of Knee Society Knee Score (weighted mean difference 0.65, 95% CI -4.41 to 5.70, P = .80) and Knee Society Function scores (weighted mean difference 0.01, 95% CI -3.26 to 3.28, P = .99), Oxford Knee Score (weighted mean difference 3.36, 95% CI -3.48 to 10.00, P = .34), Western Ontario and McMaster Universities Arthritis Index (weighted mean difference -7.47, 95% CI -23.94 to 8.99, P = .37), and Visual Analogue Scale score for pain (weighted mean difference -0.10, 95% CI -0.41 to 0.21, P = .53).

CONSLUSION

Current literature is insufficient to address whether there is a benefit of PSI in total knee arthroplasty in terms of improvement in functional outcomes.

Patient-specific instrumentation in total knee arthroplasty. Should we adopt it?

Total knee arthroplasty (TKA) is a surgical procedure of paramount relevance that restores a substantial degree of function in arthritic knees. Increased consideration has been given to the influence of limb alignment on longevity after TKA, as errors in component placement can be associated with inferior function and compromised long-term performance. Consequently, numerous studies comparing patient-specific instrumentation (PSI) to standard instruments (SI) have been published. Patient-specific approaches use preoperative imaging to create specific materials for each patient's anatomy and were designed to achieve a higher rate of success in TKA, causing the entire procedure to be more efficient and cost-effective. However, it is not clear to what degree these studies support the potential advantages of PSI. Thus, the present study aimed to review the current evidence comparing PSI to SI, concerning alignment, cost-effectiveness, and postoperative functional evaluation.

Patient-specific instrumentation does not improve radiographic alignment or clinical outcomes after total knee arthroplasty

Background and purpose - Patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) has been introduced to improve alignment and reduce outliers, increase efficiency, and reduce operation time. In order to improve our understanding of the outcomes of patient-specific instrumentation, we conducted a meta-analysis. Patients and methods - We identified randomized and quasi-randomized controlled trials (RCTs) comparing patient-specific and conventional instrumentation in TKA. Weighted mean differences and risk ratios were determined for radiographic accuracy, operation time, hospital stay, blood loss, number of surgical trays required, and patient-reported outcome measures. Results - 21 RCTs involving 1,587 TKAs were included. Patient-specific instrumentation resulted in slightly more accurate hip-knee-ankle axis (0.3°), coronal femoral alignment (0.3°, femoral flexion (0.9°), tibial slope (0.7°), and femoral component rotation (0.5°). The risk ratio of a coronal plane outlier (> 3° deviation of chosen target) for the tibial component was statistically significantly increased in the PSI group (RR =1.64). No significance was found for other radiographic measures. Operation time, blood loss, and transfusion rate were similar. Hospital stay was significantly shortened, by approximately 8 h, and the number of surgical trays used decreased by 4 in the PSI group. Knee Society scores and Oxford knee scores were similar. Interpretation - Patient-specific instrumentation does not result in clinically meaningful improvement in alignment, fewer outliers, or better early patient-reported outcome measures. Efficiency is improved by reducing the number of trays used, but PSI does not reduce operation time.

Innovations in Total Knee Arthroplasty: Improved Technical Precision, But Unclear Clinical Benefits

Total knee arthroplasty has been an effective treatment for advanced degenerative joint disease. Traditional knee designs and surgical approaches have resulted in consistently high performance, but some patients may remain dissatisfied after their surgery. Several surgical innovations, including accelerometer-based navigation, patient-specific instrumentation, and robotic-assisted total knee arthroplasty, have been developed to improve the accuracy and precision of total knee arthroplasty surgery, with anticipated secondary benefits of improved functional outcomes and implant survivorship. This article reviews the current status of these technologies as reported in contemporary orthopedic literature. [Orthopedics. 2016; 39(4):217-220.].

Improving outcomes in total knee arthroplasty-do navigation or customized implants have a role?

Modern total knee arthroplasty is effective at treating the pain and disability associated with osteoarthritis. The number of total knee replacements done in the USA continues to increase. Despite the great care taken during all of these procedures, some patients remain dissatisfied with their outcome. While this dissatisfaction is likely multifactorial, malalignment of the prosthetic components is a major cause of postoperative complications. A neutral mechanical axis plus or minus 3° is felt to have a positive impact on the survivorship of the prosthesis. Conventional instrumentation has been shown to have a significant number of total knee replacements that lie well outside a neutral coronal alignment. With that in mind, significant effort has been placed into the development of technology to improve the overall alignment of the prosthesis. In order to reduce the number of outliers, several companies have developed cost-effective systems to aid the surgeon in achieving a more predictably aligned prosthesis in all three planes. We will review the literature that is available regarding several of these tools to examine if navigation or custom guides improve outcomes in total knee arthroplasty. Our review supports that while both navigation and custom implants guides seem to be a cost effective way to achieve a predictable mechanical alignment of a total knee prosthesis therefore reducing the number of outliers, the cost may be increased operative times with no perceived difference in patient satisfaction with navigation custom guides.

Patient-specific cutting blocks: Of Unproven Value

Patient specific instrumentation (PSI) uses advanced imaging of the knee (CT or MRI) to generate individualised cutting blocks aimed to make the procedure of total knee arthroplasty (TKA) more accurate and efficient. However, in this era of healthcare cost consciousness, the value of new technologies needs to be critically evaluated. There have been several comparative studies looking at PSI versus standard instrumentation. Most compare PSI with conventional instrumentation in terms of alignment in the coronal plane, operative time and surgical efficiency, cost effectiveness and short-term outcomes. Several systematic reviews and meta-analyses have also been published. PSI has not been shown to be superior compared with conventional instrumentation in its ability to restore traditional mechanical alignment in primary TKA. Most studies show comparative efficacy and no decrease in the number of outliers in either group. In terms of operative time and efficiency, PSI tended towards decreasing operative time, saving a mean of five minutes per patient (0 to 20). Furthermore, while some cost savings could be realised with less operative time and reduced instrumentation per patient, these savings were overcome by the cost of the CT/MRI and the cutting blocks. Finally, there was no evidence that PSI positively affected clinical outcomes at two days, two months, or two years. Consequently, current evidence does not support routine use of PSI in routine primary TKA.

[The MyKnee® patient-specific system. Rationale, Technique and Results]

BACKGROUND

Adequate three-dimensional component positioning and restoration of overall limb alignment are primary goals in total knee arthroplasty. Patient-specific instrumentation (PSI) is a potential way to improve accuracy of knee reconstruction surgery. However, currently available literature regarding the reliability of PSI shows inconsistent results for limb alignment restoration and component positioning.

OBJECTIVES

The purpose of this article is to illustrate the rationale for using PSI in total knee arthroplasty, to demonstrate the surgical technique, and to present our outcome with the MyKnee(®) system.

METHODS

We illustrate in detail the logistics and workflow involved in PSI for total knee arthroplasty. Finally, we present clinical and radiological results of patients undergoing knee arthroplasty using the MyKnee(®) system compared to a conventional instrumentation group.

RESULTS

PSI significantly improved accuracy and reduced the number of outliers regarding neutral mechanical alignment restoration as well as three-dimensional component positioning compared to conventional instrumentation. The early clinical outcome was comparable between the two instrumentation groups. However, clinical outcome in the subgroup of patients within ± 3° from neutral mechanical limb alignment was superior to limb alignment outliers.

CONCLUSION

The MyKnee(®) PSI system presents a reliable way to improve the accuracy of mechanical limb alignment restoration and three-dimensional component positioning in total knee arthroplasty. Nonetheless, an adequate surgical technique remains the crucial factor for successful total knee reconstruction.

The Mark Coventry Award: Custom Cutting Guides Do Not Improve Total Knee Arthroplasty Clinical Outcomes at 2 Years Followup

BACKGROUND

Custom cutting guides (CCGs; sometimes called patient-specific instrumentation [PSI]) in total knee arthroplasty (TKA) use preoperative three-dimensional imaging to fabricate cutting blocks specific to a patient's native anatomy.

QUESTIONS/PURPOSES

The purposes of this study were to determine if CCGs (1) improve clinical outcomes as measured by UCLA activity, SF-12, and Oxford knee scores; and (2) coronal mechanical alignment versus standard alignment guides.

METHODS

This was a retrospective cohort study of patients undergoing primary TKA using the same cruciate-retaining, cemented TKA system between January 2009 and April 2012. Patients were included if they were candidates for a unilateral, cruciate-retaining TKA and met other prespecified criteria; patients were allowed to self-select either an MRI-based CCG procedure or standard TKA. Ninety-seven of 120 (80.8%) patients in the standard and 104 of 124 (83.9%, p = 0.5) in the CCG cohort with a minimum of 1-year followup were available for analysis. The first 95 patients in the standard (mean followup, 3 years; range, 1-4 years) and CCG (mean followup, 2 years; range, 1-4 years) cohorts were compared. The alignment goal for all TKAs was a hip-knee-ankle (HKA) angle of 0°. UCLA, SF-12, and Oxford knee scores were collected preoperatively and at each patient's most recent followup visit. Postoperative, rotationally controlled coronal scout CT scans were used to measure HKA alignment. Independent-sample t-tests and chi-square tests were used for comparisons with a p value ≤ 0.05 considered significant.

RESULTS

At the most recent followup, no differences were present between the two cohorts for range of motion (114° ± 14° in CCG versus 115° ± 15° in standard, p = 0.7), UCLA (6 ± 2 in CCG versus 6 ± 2 in standard, p = 0.7), SF-12 physical (44 ± 12 in CCG versus 41 ± 12 in standard, p = 0.07), or Oxford knee scores (39 ± 9 in CCG versus 37 ± 10 in standard, p = 0.1). No differences were present for the incremental improvement in the UCLA (1 ± 4 in CCG versus 1 ± 3 in standard, p = 0.5), SF-12 physical (12 ± 20 in CCG versus 11 ± 21, p = 0.8), or Oxford knee scores (16 ± 9 in CCG versus 19 ± 10 in standard, p = 0.1) from preoperatively to postoperatively. There was no difference in the percentage of outliers for alignment (23% in standard versus 31% in CCG with HKA outside of 0° ± 3°; p = 0.2) between the two cohorts.

CONCLUSIONS

At a mean followup of greater than 2 years, CCGs fail to demonstrate any advantages in validated knee outcome measure scores or coronal alignment as measured by CT scan versus the use of standard instrumentation in TKA. The clinical benefit of CCGs must be proven before continued implementation of this technology.

LEVEL OF EVIDENCE

Level III, retrospective controlled study.

Patient-specific instrumentation improved mechanical alignment, while early clinical outcome was comparable to conventional instrumentation in TKA

PURPOSE

The aim of this prospective study was to compare early clinical outcome, radiological limb alignment, and three-dimensional (3D)-component positioning between conventional and computed tomography (CT)-based patient-specific instrumentation (PSI) in primary mobile-bearing total knee arthroplasty (TKA).

METHODS

Two hundred ninety consecutive patients (300 knees) with severe, debilitating osteoarthritis scheduled for TKA were included in this study using either conventional instrumentation (CVI, n = 150) or PSI (n = 150). Patients were clinically assessed before and 2 years after surgery according to the Knee-Society-Score (KSS) and the visual-analog-scale for pain (VAS). Additionally, the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and the Oxford-Knee-Score (OKS) were collected at follow-up. To evaluate accuracy of CVI and PSI, hip-knee-ankle angle (HKA) and 3D-component positioning were assessed on postoperative radiographs and CT.

RESULTS

Data of 222 knees (CVI: n = 108, PSI: n = 114) were available for analysis after a mean follow-up of 28.6 ± 5.2 months. At the early follow-up, clinical outcome (KSS, VAS, WOMAC, OKS) was comparable between the two groups. Mean HKA-deviation from the targeted neutral mechanical axis (CVI: 2.2° ± 1.7°; PSI: 1.5° ± 1.4°; p < 0.001), rates of outliers (CVI: 22.2%; PSI: 9.6%; p = 0.016), and 3D-component positioning outliers were significantly lower in the PSI group. Non-outliers (HKA: 180° ± 3°) showed better clinical results than outliers at the 2-year follow-up.

CONCLUSIONS

CT-based PSI compared with CVI improves accuracy of mechanical alignment restoration and 3D-component positioning in primary TKA. While clinical outcome was comparable between the two instrumentation groups at early follow-up, significantly inferior outcome was detected in the subgroup of HKA-outliers.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.