Alignment In Total Knee Replacement Research Articles

Reliable prediction of implant size and axial alignment in AI-based 3D preoperative planning for total knee arthroplasty

The size and axial alignment of prostheses, when planned during total knee replacement (TKA) are critical for recovery of knee function and improvement of knee pain symptoms. This research aims to study the effect of artificial intelligence (AI)-based preoperative three dimensional (3D) planning technology on prosthesis size and axial alignment planning in TKA, and to compare its advantages with two dimensional (2D) X-ray template measurement technology. A total of 60 patients with knee osteoarthritis (KOA) who underwent TKA for the first time were included in the AI (n = 30) and 2D (n = 30) groups. The preoperative and postoperative prosthesis size, femoral valgus correction angle (VCA) and hip-knee-ankle angle (HKA) were recorded and compared between the two groups. The results of the University of Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the American Knee Association Score (AKS) were evaluated before surgery, 3 months, 6 months, and 12 months after surgery. The accuracy of prosthesis size, VCA and HKA prediction in AI group was significantly higher than that in 2D group (P < 0.05). The WOMAC and AKS scores in AI group at 3 months, 6 months and 12 months after surgery were better than those in 2D group (P < 0.05). Both groups showed significant improvement in WOMAC and AKS scores at 12 months follow-up. AI-based preoperative 3D planning technique has more reliable planning effect for prosthesis size and axial alignment in TKA.

A Prospective Randomized Study on Whether Computer Navigation Is Better Than Conventional Total Knee Replacement in Terms of Short-Term Functional and Clinical Outcomes.

Computer navigation results in better radiological alignment in total knee replacement (TKR). However, functional and clinical outcomes are equally good in conventional TKR. This study aims to compare the functional and clinical outcomes in patients undergoing navigated and conventional TKR. A prospective randomized study between navigated TKR (NKR/Group I) and conventional TKR (CKR/Group II) was carried out. Functional outcome was analyzed using the Oxford Knee Score (OKS) and Western Ontario and McMaster UniversitiesArthritis Index (WOMAC) score. Clinical outcome was evaluated as knee range of motion. Thirty-nine patients (68 knees) were randomized into two groups: I and II. The mean follow-up was 26 months. There was no statistically significant difference between the two groups with respect to knee range of motion, OKS, and WOMAC score at the final follow-up. We concluded that there is no difference in clinical and functional outcomes between navigated and conventional TKR.

Postoperative limb alignment in total knee replacement. Conventional versus navigated versus robotic techniques.

Our objective was to compare the coronal mechanical axis after total knee replacement (TKR) obtained in three groups of patients subjected to conventional, navigated, and robotic surgery. Retrospective analysis. 124 knees were included (36 conventional, 41 navigated, 47 robotic). No statistically significant differences were found between the postOp tibiofemoral angle of the conventional, navigated and robotic groups (p=0.396). A repeated-measure analysis of preOp-to-postOp also found no significant differences (p=0.387). There were no differences in the proportion of outliers (3-degree) found (p=0.211). Nevertheless, a higher proportion of patients in the robotic group improved their mechanical alignment, as compared with conventional surgery (p=0.023), although no differences were found when comparing with navigation (p=0.121). No statistically significant differences were found with respect to the postOp alignment achieved. However, statistically significant differences were detected between robotic and conventional surgery when considering the percentage of patients with improved limb alignment.

Mechanical Alignment in Knee Replacement Homogenizes Postoperative Coronal Hip-Knee-Ankle Angle in Varus Knees: A Navigation-Based Study.

After knee replacement, postoperative lower limb alignment is influenced by the geometry of the prosthesis position and surrounding soft tissue that contributes to the hip-knee-ankle (HKA) angle. The purpose of this study is to determine the dynamic coronal HKA angle after mechanical alignment in total knee replacement using computer navigation. We conducted a pre-post design study of 71 patients with varus osteoarthritic knees on which total knee arthroplasty was performed. The HKA was measured before and at the end of the surgical procedure with the patient in the supine position using a navigation system at 30, 60, and 90 degrees of knee flexion. Postoperative implant position and flexion and extension gaps were assessed. HKA was clustered in three preoperative dynamic patterns (PDPs; Varus-Neutral, Varus-Valgus, and Varus-Varus). There were statistically significant differences in the dynamic coronal HKA between the preoperative and postoperative statuses after mechanically aligned knee replacement (with p < 0.0001) Before the surgical procedure, statistically significant differences were found between patterns at any angle of flexion confirming a well-differentiated preoperative dynamic behavior between the three groups. Postoperatively, 98.6% (71 out of 72) of the knees were within ± 3 degrees of the HKA at full extension. Fifty-eight knees (80.6%) were assessed to a "within-range" postoperative dynamic alignment at any grade of flexion considered. There are differences between the preoperative and postoperative status of the dynamic coronal HKA angle after mechanically aligned knee replacement. We proposed that an excellent dynamic HKA alignment is achieved not only at full extension within the range of 0 ± 3 degrees but also when this alignment is maintained at 30, 60, and 90 degrees.

Evaluation of tibial tray coronal plane alignment in total knee replacement using intramedullary JIG-a prospective study

Introduction: Long term survivorship in total knee replacement [TKR] is significantly dependant on prosthesis alignment. In a standard total knee replacement, tibial component alignment is a key factor for the long-term success of the surgery. Materials and Methods: A prospective observational study on 176 subjects who underwent TKR with intramedullary jig for tibial alignment with a minimum follow up period of 6 months was conducted in the Department of orthopaedics, KIMS Al Shifasuper-specialty hospital, Kerala. The Tibial component alignmentwas measured by the Tibial Component Angle [TCA] and Error in Tibial trayalignment. The other outcome variables were knee score, functional score, and Tourniquet time. Results: The mean TCA in the study population was 90.56o±1.194o ranging from 86.45o to 94.05o. The mean error observed in tibial tray alignment was -0.56±1.199 degrees, ranging from -0.45 to + 3.55 degrees. Accuracy of TCA within 90 ± 2 degrees was achieved in 91.48% of subjects. The mean knee score at 6months was 89.45 ± 3.83. The mean functional score at 6months was 87.55 ± 4.93. The mean tourniquet time was 59.08 ± 5.88 minutes. Conclusions: Intramedullary tibial referencing guide can be used in TKR with great accuracy (91.48%) to achieve desired coronal plane tibial component alignment (90o ±2o). When TCA was accurate, knee score and functional score were better than non-accurate TCA cases

Component Alignment in Total knee Replacement

Component Alignment in Total knee Replacement

The effect of coronal alignment on the docotr-derived outcome, patient-reported outcome, and the patient satisfaction after total knee arthroplasty

Purpose: Neutral mechanical alignment that lower limbs functional axis passes the knee joint center is the aim of coronal alignment in total knee replacement (TKA). This was thought to be important from the viewpoint of implant survival. However, the influence of coronal alignment for clinical results of TKA is not clear. Recently, not only doctor-derived outcome but also patient-reported outcome and the patients' satisfaction are important for evaluate the result of TKA. The objective of this study is to investigate the influence of postoperative coronal alignment of TKA for doctor-derived outcome, patient-reported outcome, and the patients' satisfaction. Methods: This study included 219 knees (female 189 knees and male 30 knees) who underwent primary TKA for varus-type osteoarthritis, with mean age 73.4 years (34-89 years). Patients were divided into 4 group based on hip knee ankle-angle (HKA angle): valgus (HKA angle >183), neutral (HKA angle 180±3,), mild varus (177> HKA angle >174), and severe varus (HKA<174). Flexion angle and Knee Society Score as doctor-derived outcome, Knee injury Osteoarthritis Outcome Score as patient-reported outcome, and patients' satisfaction (Visual Analogue Scale) were compared among four groups using Tukey-Kramer method. Furthermore, we inspected the correlation of preoperative HKA angle and the amount of change of HKA angle and clinical results using Spearman rank correlation coefficient. (P<0.05 is significant). Results: There was no significant difference in all clinical scores among four groups. Moreover, no significant correlation was seen between i) preoperative HKA angle, ii) the amount of change of HKA angle and clinical results. Conclusions: To date, neutral mechanical alignment has been considered to be the ideal coronal alignment in TKA. However there are a few papers that mild varus is better, since the concept called constitutional varus was reported. The relations between pre- and post-operative coronal alignment and clinical results were not seen in this study. We need to reexamine the ideal alignment in TKA. The coronal alignment may not influence the clinical results in TKA.

Using Bayesian statistics to estimate the likelihood a new trial will demonstrate the efficacy of a new treatment

BackgroundThe common frequentist approach is limited in providing investigators with appropriate measures for conducting a new trial. To answer such important questions and one has to look at Bayesian statistics.MethodsAs a worked example, we conducted a Bayesian cumulative meta-analysis to summarize the benefit of patient-specific instrumentation on the alignment of total knee replacement from previously published evidence. Data were sourced from Medline, Embase, and Cochrane databases. All randomised controlled comparisons of the effect of patient-specific instrumentation on the coronal alignment of total knee replacement were included. The main outcome was the risk difference measured by the proportion of failures in the control group minus the proportion of failures in the experimental group. Through Bayesian statistics, we estimated cumulatively over publication time of the trial results: the posterior probabilities that the risk difference was more than 5 and 10%; the posterior probabilities that given the results of all previous published trials an additional fictive trial would achieve a risk difference of at least 5%; and the predictive probabilities that observed failure rate differ from 5% across arms.ResultsThirteen trials were identified including 1092 patients, 554 in the experimental group and 538 in the control group. The cumulative mean risk difference was 0.5% (95% CrI: −5.7%; +4.5%). The posterior probabilities that the risk difference be superior to 5 and 10% was less than 5% after trial #4 and trial #2 respectively. The predictive probability that the difference in failure rates was at least 5% dropped from 45% after the first trial down to 11% after the 13th. Last, only unrealistic trial design parameters could change the overall evidence accumulated to date.ConclusionsBayesian probabilities are readily understandable when discussing the relevance of performing a new trial. It provides investigators the current probability that an experimental treatment be superior to a reference treatment. In case a trial is designed, it also provides the predictive probability that this new trial will reach the targeted risk difference in failure rates.Trial registrationCRD42015024176.

The accuracy of Intramedullary Femoral alignment in Total Knee Replacement in the prescence of ipsilateral Hip Replacement

Objectives:During total knee replacement (TKR) surgery, the most commonly used method for aligning the distal femur appropriately is via an intramedullary (IM) distal femoral alignment rod. The alignment of the rod itself is reliant on the isthmus which is used to most accurately place the rod in the correct anatomical axis. In the instance of something preventing the rod from entering the isthmus correctly, such as a hip replacement, then the degree of accuracy could be assumed to be even less. Mechanical-anatomical malalignment has been shown to decrease the implant (TKR) survival and so methods of increasing accuracy of alignment relative to the mechanical axis have been developed. At present the most accurate method intraoperatively is computer navigation and several studies have demonstrated improved alignment. An increasing number of patients year on year are having both knee and hip replacements and as the population ages the likelihood of having both a knee and hip replacement will also increase. We propose that the presence of a hip replacement within the isthmus of the femur may further decrease the accuracy of the IM alignment of the femur leading to incorrect implant positioning.Methods:The study was conducted on 10 cadaveric specimens (20 femurs). Computational navigation instrumentation was attached in turn to each femur and the ideal alignment data recorded in a standard fashion by a single operator (principal investigator). A standard entry port was then be made in the femur for the introduction of the IM rod. An IM rod was then inserted with the distal femoral cutting block in the accepted position recorded blindly on the computer navigation (both in terms of varus/valgus alignment to the mechanical axis and the degree of flexion). The process was then repeated at 3 levels to represent primary and revision hip lengths from the greater trochanter (replicating the changes that would occur in the presence of a hip replacement) The process was recorded three times at each level.Results:The resection angles between the cutting surface and the mechanical axis were measured and collected by means of computer navigation system. The results show that the IM alignment had mean Valgus of 0 degrees +/- 0.8 but with a hip replacement in situ this increased to 0.46 degrees +/- 1.49 (range 2.5 varus to 4.5 valgus), with a revision stem 0.825 +/- 1.68 (range 2.5 varus to 4.5 valgus) and long stemmed revision 1.325 +/- 2.09 (range 5 varus to 6.5 valgus). In terms of Flexion IM alignment had a mean flexion of 0.92 +/- 1.7 (range 3 extension to 4 flexion) but with a hip replacement in situ this increased to 1.88 degrees +/- 2.03 (range 2.5 extension to 8.5 flexion), with a revision stem 2.35 +/- 2.2 (range 2.5 extension to 8 flexion) and long stemmed revision 2.75 +/- 2.16 (range 3.5 extension to 7 flexion).Conclusion:This Study concludes that the prescence of a hip replacement, in particular long stemmed prosthesis, further reduces the accuracy of IM alignment in the Femur for Total Knee Replacement. Consideration of an alternative method, such as navigation, should be considered in such situations.

Better joint motion and muscle activity are achieved using kinematic alignment than neutral mechanical alignment in total knee replacement

Inappropriate patellar cut during total knee arthroplasty can lead to patellar complications due to increased bone strain. In this study, we evaluated patellar bone strain of a patient who had a deeper patellar cut than the recommended.A patient-specific model based on patient preoperative data was created. The model was decoupled into two levels: knee and patella. The knee model predicted kinematics and forces on the patella during squat movement. The patella model used these values to predict bone strain after total knee arthroplasty. Mechanical properties of the patellar bone were identified with micro-finite element modeling testing of cadaveric samples. The model was validated with a robotic knee simulator and postoperative X-rays. For this patient, we compared the deeper patellar cut depth to the recommended one, and evaluated patellar bone volume with octahedral shear strain above 1%.Model predictions were consistent with experimental measurements of the robotic knee simulator and postoperative X-rays. Compared to the recommended cut, the deeper cut increased the critical strain bone volume, but by less than 3% of total patellar volume.We thus conclude that the predicted increase in patellar strain should be within an acceptable range, since this patient had no complaints 8 months after surgery. This validated patient-specific model will later be used to address other questions on groups of patients, to eventually improve surgical planning and outcome of total knee arthroplasty.

Comparison of Postoperative Alignment of Total Knee Replacement Using Computer-Assisted Navigation with Conventional Guiding System in Chinese Population with Significant Coronal Femoral Bowing: 對比傳統全膝關節置換術和電腦導航全膝關節置換術

Background/PurposeCoronal femoral bowing is common in Chinese population. This might affect the restoration of mechanical alignment in conventional total knee replacement (TKR). The aim of the study was to compare the postoperative alignment of conventional TKR with computer-assisted navigation TKR (CAN-TKR), to investigate the effect of femoral bowing on postoperative alignment in conventional TKR and to understand the role of CAN-TKR in limbs with significant femoral bowing. MethodsThis is a retrospective study of 331 knees that underwent TKR (either conventional or CAN-TKR) in our centre from January 2010 to June 2012. The incidence of coronal femoral bowing was measured. The postoperative alignments were compared between the two groups. ResultsThe incidence of excessive coronal femoral bowing was 41.4%. For patients with or without significant coronal femoral bowing, the CAN-TKR group was significantly better in restoring postoperative mechanical axis and the coronal femoral angle (p < 0.05). Proportions of outliers were also much less in the CAN-TKR group. ConclusionCAN-TKR reduces outliers in all patients, and is especially superior in restoring mechanical alignments in patients with significant coronal femoral bowing.

The Immediate Post-Operative Radiograph is an Unreliable Measure of Coronal Plane Alignment in Total Knee Replacement.

Background: Restoration of a neutral mechanical axis is a primary goal of total knee replacement (TKR). A mechanical axis within 3° of neutral has been correlated with improved implant longevity, function, and patient satisfaction. We hypothesize that the immediate post-operative radiograph is an unreliable method of measuring alignment following TKR surgery.Methods: Seventy-five consecutive patients had supine X-rays performed on day two post-operatively followed by standing long-leg radiographs (LLRs) 6 weeks post-operatively. Correlation was sought between the mechanical axis measured on the LLR and surrogate markers of alignment on the post-operative X-ray including component alignment and an estimation of anatomical alignment using the available length of femoral and tibial shafts. Inter- and intra-observer reliabilities were assessed.Results: The mean mechanical axis on the LLR was 180.5 (SD 3.0, range 175.1–187.1). Mean offset between anatomical axis and mechanical axis was 6.4°. The mean anatomical axis measured on the short-leg X-ray was 174.9 (SD 2.4, range 169.5–181.3). Mechanical axis on the LLR was compared to the anatomical axis measured on the short-leg radiograph (SLR) + 6° with an interclass correlation coefficient of 0.588 (p < 0.001). The level of disagreement between the short- and long-leg X-rays was assessed using the Bland–Altman method and demonstrated clinically important discrepancies of 5 or more degrees in 9% of cases. Inter- and intra-observer agreements were high on all measures (p < 0.001).Conclusion: The long-leg weight bearing X-ray is an essential tool to accurately assess coronal plane alignment post TKR. While the immediate post-operative X-ray taken supine provides useful information to the surgeon on any immediate complications, our results indicate that it cannot be relied upon to determine correct restoration of the mechanical axis.

Coronal alignment in total knee replacement: historical review, contemporary analysis, and future direction.

Substantial healthcare resources have been devoted to computer navigation and patient-specific instrumentation systems that improve the reproducibility with which neutral mechanical alignment can be achieved following total knee replacement (TKR). This choice of alignment is based on the long-held tenet that the alignment of the limb post-operatively should be within 3° of a neutral mechanical axis. Several recent studies have demonstrated no significant difference in survivorship when comparing well aligned versus malaligned TKRs. Our aim was to review the anatomical alignment of the knee, the historical and contemporary data on a neutral mechanical axis in TKR, and the feasibility of kinematically-aligned TKRs. Review of the literature suggests that a neutral mechanical axis remains the optimal guide to alignment.

Analysis and Evaluation of Limb Alignment in Total Knee Replacement

Numerous factors contribute to success of a total knee replacement (TKR); including surgical instruments, operational methods, positioning of prosthesis, cementing techniques, surgical experience and limb alignment. Limb alignment of±30 has been rationally thought to be an acceptable alignment and clinical studies have to certain extent validated these assumptions. However these alignment boundaries still remain a hypothesis, as±30 is an arbitrary value; therefore need validation. In this work, the main objective was to analyze the pattern of relative stress distribution in TKR if the axial alignment is gradually increased or decreased including the range of±3°. This work shows an application of digital modeling of limbs and implants, where CAD has been applied to design and assembly of femur, tibia and knee implants. The analysis was carried out at different alignment positions in Ansys workbench 14.0. It was found that within±4° the rise in stress across the model surfaces is not much, however beyond±5°...

The effect of the posterior slope of the tibial plateau osteotomy with a rotational error on tibial component malalignment in total knee replacement

We performed a CT-based computer simulation study to determine how the relationship between any inbuilt posterior slope in the proximal tibial osteotomy and cutting jig rotational orientation errors affect tibial component alignment in total knee replacement. Four different posterior slopes (3°, 5°, 7° and 10°), each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were simulated. Tibial cutting block malalignment of 20° of external rotation can produce varus malalignment of 2.4° and 3.5° with a 7° and a 10° sloped cutting jig, respectively. Care must be taken in orientating the cutting jig in the sagittal plane when making a posterior sloped proximal tibial osteotomy in total knee replacement.

A prospective randomised controlled study of patient-specific cutting guides compared with conventional instrumentation in total knee replacement

Patient-specific cutting guides (PSCGs) are designed to improve the accuracy of alignment of total knee replacement (TKR). We compared the accuracy of limb alignment and component positioning after TKR performed using PSCGs or conventional instrumentation. A total of 80 patients were randomised to undergo TKR with either of the different forms of instrumentation, and radiological outcomes and peri-operative factors such as operating time were assessed. No significant difference was observed between the groups in terms of tibiofemoral angle or femoral component alignment. Although the tibial component in the PSCGs group was measurably closer to neutral alignment than in the conventional group, the size of the difference was very small (89.8° (sd 1.2) vs 90.5° (sd 1.6); p = 0.030). This new technology slightly shortened the bone-cutting time by a mean of 3.6 minutes (p < 0.001) and the operating time by a mean 5.1 minutes (p = 0.019), without tangible differences in post-operative blood loss (p = 0.528) or need for blood transfusion (p = 0.789). This study demonstrated that both PSCGs and conventional instrumentation restore limb alignment and place the components with the similar accuracy. The minimal advantages of PSCGs in terms of consistency of alignment or operative time are unlikely to be clinically relevant.

Alignment in total knee replacement

The advent of computer-assisted knee replacement surgery has focused interest on the alignment of the components. However, there is confusion at times between the alignment of the limb as a whole and that of the components. The interaction between them is discussed in this article. Alignment is expressed relative to some reference axis or plane and measurements will vary depending on what is selected as the reference. The validity of different reference axes is discussed. Varying prosthetic alignment has direct implications for surrounding soft-tissue tension. In this context the interaction between alignment and soft-tissue balance is explored and the current knowledge of the relationship between alignment and outcome is summarised.

The evaluation of post-operative alignment in total knee replacement using a CT-based navigation system

We compared the alignment of 39 total knee replacements implanted using the conventional alignment guide system with 37 implanted using a CT-based navigation system, performed by a single surgeon. The knees were evaluated using full-length weight-bearing anteroposterior radiographs, lateral radiographs and CT scans. The mean hip-knee-ankle angle, coronal femoral component angle and coronal tibial component angle were 181.8 degrees (174.2 degrees to 188.3 degrees), 88.5 degrees (84.0 degrees to 91.8 degrees) and 89.7 degrees (86.3 degrees to 95.1 degrees), respectively for the conventional group and 180.8 degrees (178.2 degrees to 185.1 degrees), 89.3 degrees (85.8 degrees to 92.0 degrees) and 89.9 degrees (88.0 degrees to 93.0 degrees), respectively for the navigated group. The mean sagittal femoral component angle was 85.5 degrees (80.6 degrees to 92.8 degrees) for the conventional group and 89.6 degrees (85.5 degrees to 94.0 degrees) for the navigated group. The mean rotational femoral and tibial component angles were -0.7 degrees (-8.8 degrees to 9.8 degrees) and -3.3 degrees (-16.8 degrees to 5.8 degrees) for the conventional group and -0.6 degrees (-3.5 degrees to 3.0 degrees) and 0.3 degrees (-5.3 degrees to 7.7 degrees) for the navigated group. The ideal angles of all alignments in the navigated group were obtained at significantly higher rates than in the conventional group. Our results demonstrated significant improvements in component positioning with a CT-based navigation system, especially with respect to rotational alignment.

An Aid to Tibial Alignment in Total Knee Replacement

An Aid to Tibial Alignment in Total Knee Replacement

Technical Notes and Tips: An Aid to Tibial Alignment in Total Knee Replacement

Technical Notes and Tips: An Aid to Tibial Alignment in Total Knee Replacement