Instrumentation In Total Knee Arthroplasty Research Articles

Comparing a Robotic Imageless Second-generation System to Traditional Instrumentation in Total Knee Arthroplasty: A Matched Cohort Analysis

IntroductionRobotic-assisted total knee arthroplasty (rTKA) has gained interest from patients and surgeons alike. Robotic systems assist with gap balancing and bone cut accuracy, which can theoretically minimize post-operative pain by decreasing soft tissue damage. This study compared perioperative results, 30- and 90-day complications, patient-reported outcomes (PROs), and survivorship to all-cause revisions between patients undergoing traditional versus rTKA. MethodsA total of 430 TKAs (215 rTKA, 215 traditional) by two fellowship trained arthroplasty surgeons were retrospectively reviewed from 2017 to 2022. All rTKAs were performed using the CORI Surgical System (Smith & Nephew, Memphis, Tennessee). Cohorts were propensity score matched by age, sex, body mass index, and American Society of Anesthesiologist classification. Blood loss, surgical times, length of stays, 30- and 90-day complications, pain scores and PROs were compared with univariable analyses. Cox regression analyses evaluated survival to all-cause revisions. ResultsPatients undergoing rTKA had a higher incidence of discharge home (86.5% to 60.0%) (p<0.01). There was no difference in blood loss or surgical time. rTKA pain scores were lower in-hospital mean 2 (range, 0 to 9) vs 3 (range, 0 to 9) (p=0.02) as well as at one-year post-operatively, mean 1 (range, 0 to 7) vs 2 (range, 0 to 10) (p=0.02). Cox hazard ratio demonstrated no difference in survival to all-cause revisions (HR 1.3; CI 0.5 to 3.7) (p=0.64). ConclusionThis matched cohort analysis demonstrated potential short-term benefits associated with imageless second generation rTKA including improved early post-operative pain, without compromising survivorship to all-cause revisions.

First long-term analysis of survival and clinical outcome in patient-specific instrumentation for total knee arthroplasty: follow-up of a prospective cohort study.

Patient-specific instrumentation (PSI) was introduced to improve post-operative alignment, and consequently the revision rate and clinical results after total knee arthroplasty (TKA). Short- to mid-term data are conflicting regarding these theoretical advantages of PSI. The purpose of this retrospective analysis was to evaluate the survival rate and clinical outcome in PSI TKA 8.4 years after initial surgery. To our knowledge, no other study investigated long-term follow-up of TKA procedures using PSI. From a total cohort of 184 consecutive patients (200 TKA) 136 patients (144 TKA, 72%) were prospectively analysed at a mean follow-up of 8.4 years (±0.4). A survival analysis with all-cause revision of TKA as endpoint was performed. Patient-reported outcome measures (PROMs) were obtained preoperatively and after 1-, 2-, 5-, and 8.4-years of follow-up. Differences between these moments of follow-up were analysed. At final follow-up, 4 TKAs (2%) had undergone revision, all between 2-4 years after primary surgery. Reasons for revision were late infection, aseptic loosening, instability and polyethylene insert breakage. The median score of certain PROMs (WOMAC, VAS, EQ-index, EQ-VAS) decreased compared to previous follow-up scores but were significantly higher than preoperative scores. After 8.4 years of follow-up, no additional revision surgery was performed compared to 5-years postoperatively. Certain PROMs at 8.4-year follow-up decreased compared to earlier moments of follow-up, but all PROMs improved compared to preoperative PROMs.

Robotic-assisted total knee arthroplasty results in decreased incidence of anterior femoral notching compared to posterior referenced instrumented total knee arthroplasty.

Periprosthetic fracture (PPF) is an uncommon but devastating complication after total knee arthroplasty (TKA). Anterior femoral notching (AFN) is one of a perioperative risk factor for PPF. The main purpose of this study was to compare between the rates of anterior femoral notching (AFN) and supracondylar periprosthetic femoral fracture (sPPF) of manual TKA and robotic arm-assisted TKA (RATKA). Meanwhile, blood loss, transfusion rates, inflammatory responses, complications, early clinical and radiological outcomes were also assessed. This retrospective study included 330 patients (133 RATKA and 197 manual TKA). Differences in risks of inflammatory, blood loss, complications (periprosthetic fracture and periprosthetic joint infection), pre-operative and post-operative distal lateral femoral angle (LDFA), distal femoral width (DFW), prosthesis-distal femoral width (PDFW) ratio, AFN, femoral component flexion angle (FCFA), peri-operative and post-operative functional outcomes between the RATKA and manual TKA groups were compared. The operation time and postoperative CRP level in the RATKA group was significantly longer and higher than that in the manual TKA group (p < .001). However, there was no significant difference in postoperative WBC level (p = .217), hemoglobin loss (p = .362), postoperative drainage (p = .836), and periprosthetic fracture (p = 1.000). There was no significant difference in LDFA (p > .05), DFW(p = .834), PDFW ratio (p = .089) and FCFA (p = .315) between the two groups, but the rate of AFN in the RATKA group was significantly lower than that in the manual TKA group (p < .05). There was no significant difference in ROM between the two groups on POD3, POD 90 and 1 year (p < .05), but the FJS-12 score in the RATKA group was higher than that in the manual TKA group on 1 year (p = .001). Robotic-assisted total knee arthroplasty can decrease the incidence of anterior femoral notching compared to posterior referenced instrumented total knee arthroplasty.

Comparing conventional and patient specific instrumentation in total knee arthroplasty: an early analysis of function and satisfaction

Background: Patient specific instrumentation (PSI) in TKA is a surgical technique created to improve the accuracy of implantation, surgical time, blood loss and workflow that has been a growing trend over the past decade. Our work aims to determine if there are improvements in patient satisfaction and functional results using PSI in comparison with conventional instrumentation (CI) in TKA. Methods: The authors evaluated 716 patients from the past 10 years that underwent TKA, either by PSI (n=456) or by CI (n=260). The authors recorded the WOMAC index, articular range of motion, and the six-minute walking test at pre-op and day 90 post-op. T-student and Mann-Whitney tests were used considering p&lt;0.05. Results: The functional scores achieved 90 days after surgery were better for PSI compared to CI. The respective differences are found in the extension (p=0.022), gait distance (p=0.010) and in the pain and function WOMAC index (respectively p=0.018 and p=0.020). No statistical differences were found in satisfaction. Conclusions: 90 days after TKA, the functional scores achieved with PSI were better compared to CI. However, better results in this area did not translate to significantly higher satisfaction in the patients. There seems to be a tendency in favor of better functional results in patients that underwent TKA by PSI in comparison to those submitted to CI. These results seem to follow the tendencies demonstrated in available literature.

No differences in mid-term survival and clinical outcome between CT- and MRI-based patient-specific instrumentation for total knee arthroplasty, a randomized controlled trial.

The purpose of this prospective randomized controlled trial was to compare the clinical outcome and the survival rate of total knee arthroplasty between CT- and MRI-based patient-specific instrumentation 5 years after initial surgery. At a mean follow-up of 5.8years (SD 0.3), 98 patients (64% women, loss to follow-up 28%) were included in this analysis. To assess the differences in clinical outcome, patients fulfilled PROMs preoperatively and at each follow-up moment. At final follow-up, the Forgotten Joint Score was adjusted. At final follow-up, no new patients underwent revision surgery in both groups. Regarding the clinical outcome, no statistically significant difference between the groups was found. The Forgotten Joint Score was only performed at final follow-up and showed no significant difference between both groups. At mid-term follow-up, survival rates between CT- and MRI-based patient-specific instrumentation did not show a significant difference. Regarding clinical outcome, only the EQ-5D-VAS (p < 0.040) showed a statistically significant difference over time, in favor of the MRI-group. Level I.

The Role of 3D-Printed Patient-Specific Instrumentation in Total Knee Arthroplasty: A Literature Review.

Total knee arthroplasty (TKA) is currently one of the most common orthopedic surgeries due to the ever-increasing average life expectancy. The constantneed for effective and accurate techniques was contributed to the development of three-dimensional (3D) printing in that field, especially for patient-specific instrumentation (PSI) and custom-made implants fabrication. PSI may offer numerous benefits, such as resection accuracy, mechanical axis alignment, cost-effectiveness, and time economy. Nonetheless, the results of existing studies are controversial. For this purpose, a review article of the published articles was conducted to summarize the role of 3D-printed PSI in TKA.

Cost-effectiveness of patient specific vs conventional instrumentation for total knee arthroplasty: A systematic review and meta-analysis.

Over the past years, patient specific instrumentation (PSI) for total knee arthroplasty (TKA) has been implemented and routinely used. No clear answer has been given on its associated cost and cost-effectiveness when compared to conventional instrumentation (CI) for TKA. To compare the cost and cost-effectiveness of PSI TKA compared to CI TKA. A literature search was performed in healthcare, economical healthcare, and medical databases (MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Library, EconLit). It was conducted in April 2021 and again in January 2022. Relevant literature included randomised controlled trials, retrospective studies, prospective studies, observational studies, and case control studies. All studies were assessed on methodological quality. Relevant outcomes included incremental cost-effectiveness ratio, quality-adjusted life years, total costs, imaging costs, production costs, sterilization associated costs, surgery duration costs and readmission rate costs. All eligible studies were assessed for risk of bias. Meta-analysis was performed for outcomes with sufficient data. Thirty-two studies were included into the systematic review. Two were included in the meta-analysis. 3994 PSI TKAs and 13267 CI TKAs were included in the sample size. The methodological quality of the included studies, based on Consensus on Health Economic Criteria-scores and risk of bias, ranged from average to good. PSI TKA costs less than CI TKA when considering mean operating room time and its associated costs and tray sterilization per patient case. PSI TKA costs more compared to CI TKA when considering imaging and production costs. Considering total costs per patient case, PSI TKA is more expensive in comparison to CI TKA. Meta-analysis comparing total costs for PSI TKA, and CI TKA showed a significant higher cost for PSI TKA. Cost for PSI and CI TKA can differ when considering distinct aspects of their implementation. Total costs per patient case are increased for PSI TKA when compared to CI TKA.

Transition to Robotic Total Knee Arthroplasty With Kinematic Alignment is Associated With a Short Learning Curve and Similar Acute-Period Functional Recoveries.

Background Robotic instruments are increasingly being used in total knee arthroplasty (TKA). The adoption of robotics has allowed surgeons a new level of precision and facilitated the adoption of a kinematic approach in TKA. We sought to examine one surgeon's transition from a traditional mechanical alignment technique to a modified kinematic approach by comparingshort-term recovery outcomes of robotic TKA patients with those who underwent traditionally instrumented TKAs. Methodology We examined six-week and six-month postoperative data from 99 traditionally instrumented, mechanically aligned and 66 kinematically aligned robotic TKA patients between January 2021-October 2021 and October 2021-April 2022, respectively. Robotic surgery was performed with VELYS™ (DePuy Synthes, Warsaw, IN, USA) a semi-active, imageless, table-affixed, robotic TKA solution. Results Robotic and traditionally instrumented TKAs did not differ significantly in any functional outcome measures examined, including pain scores, use of assistive devices, or range of motion at six weeks postoperatively. Robotic TKA patients had a better range of motion in knee flexion than traditional TKA patients at six months postoperatively. There were no differences in surgical complications or rates of manipulation under anesthesia within one year postoperatively. Robotic surgery tourniquet times exhibited a steep drop off and equaled traditional methods after only two robotic surgeries were performed. Conclusions Transition to a kinematic, semi-active, robotic TKA demonstrated encouraging results by demonstrating acute-period recovery of function consistent with the current standard of care, as well as a better range of motion at six months postoperatively. The learning curve of this new-to-market device was shorter than previous research on the transition to robotic TKA. Clear advantages of transitioning to robotic instrumentation by any specific functional measure are yet to be elucidated. Further randomized trials are necessary to characterize long-term outcomes.

Can a Musculoskeletal Model Adapted to Knee Implant Geometry Improve Prediction of 3D Contact Forces and Moments?

Tibiofemoral contact loads are crucial parameters in the onset and progression of osteoarthrosis. While contact loads are frequently estimated from musculoskeletal models, their customization is often limited to scaling musculoskeletal geometry or adapting muscle lines. Moreover, studies have usually focused on superior-inferior contact force without investigating three-dimensional contact loads. Using experimental data from six patients with instrumented total knee arthroplasty (TKA), this study customized a lower limb musculoskeletal model to consider the positioning and the geometry of the implant at knee level. Static optimization was performed to estimate tibiofemoral contact forces and contact moments as well as musculotendinous forces. Predictions from both a generic and a customized model were compared to the instrumented implant measurements. Both models accurately predict superior-inferior (SI) force and abduction-adduction (AA) moment. Notably, the customization improves prediction of medial-lateral (ML) force and flexion-extension (FE) moments. However, there is subject-dependent variability in the prediction of anterior-posterior (AP) force. The customized models presented here predict loads on all joint axes and in most cases improve prediction. Unexpectedly, this improvement was more limited for patients with more rotated implants, suggesting a need for further model adaptations such as muscle wrapping or redefinition of hip and ankle joint centers and axes.

Correcting for distal femoral asymmetry is necessary to determine postoperative alignment deviations from planned alignment of the femoral component

BackgroundOne method for assessing the accuracy of manual, patient-specific, navigational, and robotic-assisted total knee arthroplasty (TKA) instrumentation is to use a post-operative computer tomogram and determine the deviation of the femoral component alignment relative to the planned alignment in the native (i.e. healthy) contralateral distal femoral epiphysis. However, side-to-side asymmetry might introduce errors which inflate alignment deviations. This study quantified asymmetry in the distal femoral epiphysis. MethodsHigh resolution CT images (0.5 mm slice thickness) were acquired from bilateral lower limb specimens of 13 skeletally mature subjects with no skeletal abnormalities. Images were segmented to generate 3D femur models. Asymmetry was quantified by differences in positions and orientations required to shape-match the distal epiphysis of the mirror 3D femur model to the distal epiphysis of the contralateral 3D femur model. ResultsAsymmetry was due to random rather than systematic differences. Random differences (i.e. standard deviations) in proximal–distal (P-D) and anterior-posterior (A-P) positions were 1.1 mm and in varus-valgus (V-V) and internal-external (I-E) orientations were 0.9° and 1.3°, respectively. These represented substantial relative errors of up to 50 % in previously reported overall alignment deviations. ConclusionsAlthough small in an absolute sense, asymmetry of the distal femur epiphysis introduced substantial relative errors when assessing accuracy of femoral component alignment in TKA. When post-operative computer tomograms are used to assess the accuracy of manual, patient specific, navigational, and robotic-assisted TKA instrumentation, the overall deviation should be corrected for asymmetry to better indicate the accuracy of the surgical technique.

Kinetics influence of multibody kinematics optimisation for soft tissue artefact compensation

Soft tissue artefact (STA) remains a major source of error in human movement analysis. The multibody kinematics optimisation (MKO) approach is widely stated as a solution to reduce the effects of STA. This study aimed at assessing the influence of the MKO STA-compensation on the errors of estimation of the knee intersegment moments. Experimental data were issued from the CAMS-Knee dataset where six participants with instrumented total knee arthroplasty performed five activities of daily living: gait, downhill walking, stair descent, squat, and sit-to-stand. Kinematics was measured both on the basis of skin markers and a mobile mono-plane fluoroscope, used to obtain the STA-free bone movement. For four different lower limb models and one corresponding to a single-body kinematics optimization (SKO), knee intersegmental moments (estimated using model-derived kinematics and ground reaction force) were compared with an estimate based on the fluoroscope. Considering all participants and activities, mean root mean square differences were the largest along the adduction/abduction axis: of 3.22Nm with a SKO approach, 3.49Nm with the three-DoF knee model, and 7.66Nm, 8.52Nm, and 8.54Nm with the one-DoF knee models. Results showed that adding joint kinematics constraints can increase the estimation errors of the intersegmental moment. These errors came directly from the errors in the estimation of the position of the knee joint centre induced by the constraints. When using a MKO approach, we recommend to analyse carefully joint centre position estimates that do not remain close to the one obtained with a SKO approach.

Comparison of clinical outcomes of VISIONAIRE patient-specific instrumentation with conventional instrumentation in total knee arthroplasty: a systematic literature review and meta-analysis

IntroductionMalalignment and resulting complications are major challenges in total knee arthroplasty (TKA) which patient-specific instrumentation (PSI) is proposed to alleviate. Previous PSI meta-analyses of TKA outcomes typically do not differentiate between PSI systems and assess relatively few outcomes, so the value of their findings is limited. VISIONAIRE™ cutting guides (Smith + Nephew Inc., Memphis, TN, USA) is a PSI system based on preoperative magnetic resonance and X-ray imaging. A systematic literature review (SLR) and meta-analysis, focussed specifically on VISIONAIRE, were conducted to assess TKA accuracy, intraoperative outcomes, and postoperative outcomes, compared with conventional instrumentation (CI).Materials and methodsThe SLR was performed using PubMed, Embase, and Google Scholar databases to identify relevant studies published until March 2022. Depending on statistical heterogeneity, meta-analyses were performed for outcome measures with fixed effect (I2 < 50%) or random-effects models (I2 ≥ 50%). Dichotomous outcomes were reported as odds ratios and continuous outcomes were reported as mean differences. Descriptive analyses were performed for outcomes not amenable to meta-analysis.ResultsOutcomes for VISIONAIRE versus CI were reported in 25 studies. Compared with CI, VISIONAIRE reduced odds of mechanical outliers by 40% (p < 0.0001), with no statistically significant differences in odds of overall coronal, sagittal, or rotational plane component outliers. VISIONAIRE improved surgical efficiency (operating room, turnover, and tourniquet times reduced by 7.3% (p = 0.02), 42% (p = 0.022), and 15.9% (p = 0.01), respectively), lowering the odds of blood transfusion by 53% (p = 0.01) and shortening patients’ hospital stays (11.1% reduction; p < 0.0001). There were no significant differences between groups in incidence of postoperative complications and (descriptively analyzed) return-to-function outcomes.ConclusionOptions for PSI in TKA differ substantially, and it is important to assess the outcomes of individual systems. The current findings suggest that VISIONAIRE guides can lead to improved alignment accuracy and surgical efficiency compared with CI, without compromising postoperative safety and return-to-function outcomes.

Alignment accuracy and functional outcomes between hand-held navigation and conventional instruments in TKA: a randomized controlled trial

BackgroundThis study assessed surgical accuracy and functional outcomes using hand-held accelerometer-based navigation following total knee arthroplasty (TKA). Question: (1) Does hand-held navigation (the iAssist system) improve surgical accuracy (assessed with five parameters commonly used to evaluate surgical alignment: the hip-knee-ankle angle (HKA), femoral coronal angle (FCA), tibial coronal angle (TCA), femoral sagittal angle (FSA), and tibial slope angle (TSA)) compared to conventional instruments in TKA? (2) Which surgical alignment parameters among HKA, FCA, TCA, FSA, and TSA can obtain the most advantage from the iAssist system? (3) Does the iAssist system lead to better functional outcomes at two years of follow-up after TKA?MethodsThis parallel-group double-blinded randomized controlled trial recruited 60 patients (30 patients each in the iAssist and conventional group) with osteoarthritis who underwent primary TKA by a single surgeon at Siriraj Hospital. There was no loss to follow-up in the study. All procedures in both groups were performed using similar surgical exposure, prosthesis implant, perioperative and postoperative protocols. Participants in the iAssist group received the iAssist system as an assistive technique, while those in the conventional group only had conventional instruments. Surgical alignments (HKA, FCA, TCA, FSA, and TSA) were recorded using CT scan at six weeks post-operation. Functional outcomes were assessed with knee ROM, KSS, and EQ-5D at 6 months, 1 year and 2 years post-operation. Baseline characteristics including age, sex, the affected knee side, and body mass index were comparable between the two groups, similar to preoperative ROM, KSS, and EQ-5D.ResultsThe mean operative time was relatively longer in the iAssist than the conventional group, although not statistically significant (88.1 ± 13.7 versus 83.4 ± 21.3; p = 0.314). Among the surgical alignment parameters evaluated, FCA was the only radiographic parameter with a statistically significant difference between the two groups and was closer to 90º in the iAssist group (89.4 ± 2.2 in the iAssist versus 87.2 ± 2.1 in the conventional group; p = 0.003). Also, there was a higher proportion of outliers in the conventional than the iAssist group (23.3% versus 10%; p = 0.086). Nonetheless, HKA and TCA did not differ between the two groups (p = 0.25 and 0.096, respectively), although the percentages of outliers were higher in the conventional than the iAssist group (HKA: 26.7% vs. 13.3%; p = 0.101 and TCA: 6.7% versus 0%; p = 0.078). Likewise, we observed other radiographic parameters had no significant group differences, including FSA and TSA. Furthermore, at two years post-operation, we found no differences between the iAssist and the conventional group in knee ROM (106.7 ± 14.6 versus 108.2 ± 12.7; p = 0.324), KSS (82.5 ± 6.4 versus 83.8 ± 3.4; p = 0.324), and EQ-5D (0.9 ± 0.2 versus 1.0 ± 0.1; p = 0.217). All functional outcomes were also comparable at 6 months and 12 months of follow-up postoperatively.ConclusionThe iAssist technology increase surgical precision by allowing for a more precise FCA with fewer outliers than conventional equipment. iAssist had longer operative time. Functional outcomes and quality of life were not different.Level of evidence:I

What's New in Adult Reconstructive Knee Surgery.

What's New in Adult Reconstructive Knee Surgery.

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.

BackgroundPatient-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.MethodsA 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.ResultsThe 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).ConclusionsSUI 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.

Imageless robotic-assisted total knee arthroplasty is accurate in vivo: a retrospective study to measure the postoperative bone resection and alignment.

Conventional instruments for total knee arthroplasty (TKA) have limited accuracy. The occurrence of outliers can negatively influence the clinical outcome and long-term survival of the implant. Orthopaedic robotic systems were developed to increase the accuracy of implant positioning and bone resections. Several systems requiring preoperative imaging have shown a higher degree of precision compared to conventional instrumentation. An imageless system needs less preoperative time and preparation and is more cost effective. Aim of this study was to find out whether this system is as precise, reproduces accurately the surgeon's planning and reduces the occurrence of outliers. This retrospective study included the first 71 robotic-assisted TKA and 308 conventional TKA in 374 patients. Intraoperatively planned and actual bone resections were compared. Postoperative alignment, measured on full leg weight bearing radiographs, was related to the respective planning and statistically compared between the groups. Baseline characteristics (age, BMI, ASA, preoperative Knee Society Score and deformity) between both groups were comparable. According to the planned alignment, the postoperative mean difference was -1.01° in the robotic versus 2.05° in the conventional group. The maximum deviation was -2/+ 2.5° in the robotic and -6.6/ + 6.8° in the conventional group. According to the plan, there were no outliers above ± 3° in the robotic versus 24% in the conventional group. The mean difference between planned and measured bone resection was 0.21mm with a maximum of 2mm. The 95% confidence interval was at each position 1mm or below. The described imageless robotic system is accurate in terms of coronal alignment and bone resections. In precision, it is superior to conventional instrumentation and could therefore be used to evaluate new alignment concepts.

Patient-specific instrumentation for total knee arthroplasty improves reproducibility in the planned rotational positioning of the tibial component

BackgroundThe purpose of this study was to evaluate the reproducibility of planned component positioning including tibial rotational alignment in patient-specific instrumentation (PSI) for total knee arthroplasty (TKA).MethodsA total of 100 knees of 100 patients underwent TKA using PSI (n = 50) or the conventional method (n = 50). Full-length anteroposterior radiographs of the lower limb were taken in the standing position, and the coronal alignments of the femoral and tibial components were measured. Computed tomography (CT) images of the lower limb were obtained preoperatively and postoperatively, and the rotational alignments of the femoral and tibial components were measured. The difference from the preoperative planning in tibial rotational alignment was measured using three-dimensionally merged pre- and postoperative images. The mean values and rates of outliers in each measurement were compared between the PSI group and the conventional group.ResultsThere were no significant differences in coronal alignment of the femoral and tibial components and rotational alignment of the femoral component between the two groups. With respect to rotational alignment of the tibial component from the preoperatively planned reference axis, the PSI group showed a lower rate of outliers (internal rotation > 10°) than the conventional group (p < 0.05).ConclusionsThis study demonstrated that the difference from the preoperative planning in tibial rotational positioning was accurately evaluated using novel three-dimensional measurement method, and PSI could reduce outliers in rotational alignment of the tibial component (internal rotation > 10°). PSI is a useful technique for improving the reproducibility of the planned tibial rotational positioning in TKA.

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

BackgroundTotal 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.MethodsA literature search of electronic databases Embase, Medline and registry platform portals was conducted on the 16th 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.ResultsThere 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.ConclusionsThis 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.

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

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

Comparison of alignment and position of prosthesis between portable accelerometer-based navigation device and conventional instrumentation in total knee arthroplasty with valgus deformity

Objective: To explore the differences of alignment and position of prosthesis between portable accelerometer-based navigation device (PAD) and conventional instrumentation (CI) in total knee arthroplasty (TKA) with valgus deformity. Methods: Patients with knee osteoarthritis and valgus deformity who underwent primary TKA in Peking University Third Hospital from January 2017 to December 2020 were enrolled in this retrospective study and were divided into PAD group and CI group according to the surgical instruments. Five male patients and 44 female patients were included with a mean age of (67.2±7.0) years. The differences in preoperative general data, preoperative and postoperative alignment between the two groups were studied. Results: A total of 49 patients (25 patients in the PAD group and 24 in the CI group) were enrolled in this study. There were no statistically significant differences in gender, age, height, weight, body mass index, surgical side, preoperative hip-knee-ankle (HKA) angle, preoperative HKA angle deviation, Keblish classification and Ranawat classification between the two groups (all P>0.05). There was no significant difference in the accuracy of postoperative HKA angle (2.0°±1.4° vs 3.0°±2.2°, P=0.082), coronal femoral component angle (CFCA) (1.5°±1.2° vs 2.1°±1.6°, P=0.144) and coronal tibial component angle (CTCA) (1.2°±0.8° vs 1.3°±1.0°, P=0.695) between the two groups; but the standard deviation of the above-mentioned three indices in PAD group were all smaller than those in CI group. The rate of outliers of postoperative HKA angle of the PAD group was smaller than that in the CI group (P<0.05), but there was no significant difference in the rate of outliers of CFCA and CTCA between the two groups (both P>0.05). Conclusion: TKA assisted by PAD can provide good alignment and prosthesis position in patients with valgus deformity, and it is superior to TKA with CI in terms of precision and rate of outliers of postoperative overall alignment of lower extremity.