Mechanical Axis Alignment Research Articles

Simulation of osteotomy in total knee arthroplasty with femoral extra-articular deformity assisted by artificial intelligence: a study based on three-dimensional models

BackgroundThe impact of extra-articular deformities (EADs) on lower limb alignment and collateral ligament integrity during total knee arthroplasty (TKA) poses significant challenges, increasing surgical complexity. Our study aims to evaluate the influence of EADs on mechanical axis alignment and the risk of collateral ligament injury during TKA using an AI-assisted surgical planning system, with the goal of minimizing ligament damage through precise and scientific planning.MethodsA healthy volunteer underwent CT and MRI scans of the lower limbs. The scan images were imported into Mimics 20.0 software, and the reconstructed models were spatially aligned using 3-maticResearch 11.0 software. Using Unigraphics NX9.0 software, 50 three-dimensional models of femoral lateral joint deformities with varying positions and angles were created. Finally, TKA was simulated using the AI JOINT preoperative planning system.ResultsThe larger the deformity angle and the closer it is to the knee joint, the more pronounced the deviation of the mechanical axis. During MA-aligned osteotomy, nine types of deformities can damage the collateral ligaments. After adjusting the varus/valgus of the prosthesis within a safe range of 3° and leaving a residual 3° varus/valgus in the lower limb alignment, only the 25° varus and 25° valgus deformities located at 90% of the femoral anatomical axis remain uncorrected.ConclusionFor patients with osteoarthritis and concurrent EAD undergoing TKA, using reconstructed 3D models of the collateral ligaments for preoperative planning helps visually assess collateral ligament damage, providing a practical solution. Minimizing intra-articular osteotomies within a safe range and allowing some residual alignment deviation can reduce the risk of collateral ligament injury.

Bilateral Distal Femoral Osteotomy for Valgus Knee Deformity May Result in Improved Patient-Reported Outcome Scores

Background: The lateral opening wedge distal femoral osteotomy (DFO) is an effective treatment for genu valgum to improve mechanical alignment, decrease lateral compartment loads, and decrease the risk of knee osteoarthritis. Multiple studies have utilized outcome scores assessing functional changes related to pain and joint stability, with a focus solely on knee pain and functional outcomes. Questions/purposes: The primary aim of this study was to evaluate patient-reported outcome measures (PROMs) that assessed knee function, pain, patient’s perception of body image, and limb deformity-related quality of life, both preoperatively and at least 1-year postoperatively. Methods: In a retrospective review of nontraumatic genu valgum patients who underwent bilateral DFO, preoperative and postoperative radiographs were evaluated. Routinely collected preoperative and 1-year postoperative PROMs scores were analyzed, using the Knee Injury and Osteoarthritis Outcome Score Jr. (KOOS-JR) and the Limb Deformity-Modified Scoliosis Research Society (LD-SRS) score, in 72 limbs (36 patients): 7 men (19.44%) and 29 women (80.56%) with an average age of 35.34 ± 13.57 years. The mean follow-up time was 36.85 ± 24.43 months. Results: Overall mechanical axis deviation, lateral distal femoral angle, and mechanical axis alignment angle were significantly improved after DFO in all patients. Both PROMs also improved significantly from preoperative to postoperative scores: LD-SRS (3.10 ± 0.56 vs 4.19 ± 0.44, respectively) and KOOS-JR (63.02 ± 19.25 vs 78.06 ± 16.29, respectively). Conclusion: This retrospective review suggests that bilateral lateral opening-wedge DFOs in patients with symptomatic valgus knee deformity may be associated with improved overall knee health, limb deformity-related quality of life, and patients’ body image. Further study is needed.

Clinical and Radiological Outcomes of Computer-Assisted Navigation in Primary Total Knee Arthroplasty for Patients with Extra-articular Deformity: Systematic Review and Meta-Analysis.

Computer-assisted navigation surgery (CAS) during primary total knee arthroplasty (TKA) may help improve outcomes for patients with extra-articular deformity (EAD); however, this has not been extensively studied. Therefore, we aimed to investigate the clinical and radiological outcomes following primary TKA using CAS in patients with EAD. We searched Medline, Embase, and the Cochrane Library up to March 3, 2023 for studies investigating surgical outcomes of using the navigation system for TKA to treat patients with EAD. From 14 studies, 539 knees with EAD that underwent navigation TKA were enrolled. We investigated the knee range of motion (ROM), outcome scores at final follow-up (Knee Society Score [KSS] and Knee Functional Score [KFS]), and pre- and postoperative mechanical hip-knee-ankle (mHKA) angle using lower extremity scanogram. The meta-analysis was based on the single-arm method, and all data were pooled using a random-effects model. Following our meta-analyses, the mean knee ROM changed from 87.0° (95% confidence interval [CI], 75.9°-98.1°) preoperatively to 109.4° (95% CI, 97.9°-120.8°) postoperatively. The adjusted KSS was 93.45 points (95% CI, 88.36-98.54 points), and the adjusted KFS was 91.57 points (95% CI, 86.80-96.33 points) in knees with EAD that underwent CAS-TKA. As a radiological outcome, the mHKA angle changed from 169.53° (95% CI, 166.90°-172.16°) preoperatively to 178.81° (95% CI, 178.31°-179.30°) postoperatively. CAS-TKA yielded positive clinical results and demonstrated a satisfactory alignment of the lower limb's mechanical axis. CAS-TKA showed promise for primary TKA procedures, demonstrating favorable clinical and radiological outcomes even in complex cases involving EAD.

Robotic arm-assisted unicondylar knee arthroplasty resulted in superior radiological accuracy: a propensity score-matched analysis

IntroductionUnicompartmental knee arthroplasty (UKA) is an effective surgical treatment for medial compartment arthritis of the knee, yet surgical outcomes are directly related to surgical execution. Robotic arm-assisted surgery aims to address these difficulties by allowing for detailed preoperative planning, real-time intraoperative assessment and haptic-controlled bone removal. This study aimed to compare the clinical and radiological outcomes between conventional manual mobile bearing and robot arm-assisted fixed bearing medial UKA in our local population.Materials and methodsThis is a retrospective case–control study of 148 UKAs performed at an academic institution with a minimum of 1-year follow-up. 74 robotic arm-assisted UKAs were matched to 74 conventional UKAs via propensity score matching. Radiological outcomes included postoperative mechanical axis and individual component alignment. Clinical parameters included a range of motion, Knee Society knee score and functional assessment taken before, 6 and 12 months after the operation.ResultsRobot arm-assisted UKA produced a more neutral component coronal alignment in both femoral component (robotic -0.2 ± 2.8, manual 2.6 ± 2.3; P = 0.043) and tibial component (robotic -0.3 ± 4.0, manual 1.7 ± 5.3; P < 0.001). While the postoperative mechanical axis was comparable, robot arm-assisted UKA demonstrated a smaller posterior tibial slope (robotic 5.7 ± 2.7, manual 8.2 ± 3.3; P = 0.02). Clinical outcomes did not show any statistically significant differences.ConclusionCompared with conventional UKA, robotic arm-assisted UKA demonstrated improved component alignment and comparable clinical outcomes. Improved radiological accuracy with robotic-arm assistance demonstrated promising early results.

An updated meta-analysis comparing complications, functional, clinically relevant and radiological outcomes of accelerometer based portable navigation and conventional technique of total knee arthroplasty

IntroductionSince previous studies, including small-scale meta-analyses comparing accelerometer-based portable navigation (APN-TKA) and conventional techniqueof total knee arthroplasty (CONV-TKA), have reported divergent results, there is a need for an updated meta-analysis to compare complications, functional outcomes, clinically relevant outcomes and radiographic alignment of components. MethodsThis meta-analysis was conducted as per PRISMA guidelines. Randomised controlled trials, and non-randomised comparative cohort studies in English language on primary TKA were included. The complications compared were Deep Vein Thrombosis (DVT), Pulmonary Embolism (PE), infection, manipulation under anaesthesia (MUA) for postoperative knee stiffness, re-operation and mortality. The functional outcomes compared were the Knee Society Knee Score, Knee Society Score function, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Arthritis Index. The evaluated clinically relevant outcomes were surgical time, blood loss, drop in haematocrit, tourniquet time, postoperative knee flexion and complications). The number of radiological outliers; as well as the absolute values of the alignment of the overall prosthesis, femoral and tibial components in both coronal and sagittal planes, was assessed. ResultsTwenty-five studies were included. Both the groups were comparable in terms of preoperative demographic features. There was no difference in complications and functional outcomes. Operation time was longer in APN-TKA (p < 0.00001) but there was no difference in rest of the clinically relevant outcomes. Restoration of the lower limb mechanical axis (p = 0.003) and coronal femoral alignment angle (p = 0.0002) was better with APN. APN also significantly reduced the risk of the odds of outliers of lower limb mechanical axis (p < 0.0001), coronal femoral alignment (p = 0.03), coronal tibial alignment (p < 0.0001) and sagittal tibial alignment (p = 0.0001). ConclusionThe improvement in the accuracy of implantation by the use of APN-TKA, as determined by the overall alignments of prosthesis, or femoral and tibial components, does not necessarily translate into lesser complications and better functional and clinical outcomes. Level of evidenceTherapeutic study, Level II.

Clinical evaluation and accuracy of mechanical axis alignment in robotic total knee arthroplasty

The first experience in robotic total knee arthroplasty (RoTKA) has been obtained resulting in the questions about clinical efficiency and accuracy of lower limb alignment.Objective To clarify clinical evaluation and accuracy of alignment of the mechanical axis of the lower limb in RoTKA.Materials and methods Twenty-nine patients with osteoarthritis of the knee of Kellgren-Lawrence stage 3-4 underwent RoTKA. The knee joint was assessed with VAS, WOMAC, FJS-12; the range of motion was measured. The changes in the axis of the lower limb were evaluated on the full limb length radiographs.Results Pain before the surgery according to VAS was 5.8 ± 1.5 points, on the first day after the surgery it was 8.5 ± 1.4, on day 3 – 5.9 ± 1.2, on day 12 – 2.9 ± 1.1. The range of motion on the first day after the surgery was 99.5° ± 1.4°, three months later – 115.1° ± 1.1°, six months later – 125.6 ± 1.5°, one year later– 127.5 ± 1.6°. The WOMAC score before the surgery was 32.7 ± 3.3, after the surgery 25.1 ± 2.1, three months later 7.3 ± 1.3, six months later 2.8 ± 0.2, and after one year – 1.3 ± 0.5. The FJS-12 score 3 months after the surgery was 68.2 ± 4.1, after 6 months 80.3 ± 2.9, after one year 94.0 ± 2.1. The analysis of postoperative full length roentgenograms in 72 % of cases (n = 21) did not reveal any deviation of the mechanical axis from the planned one and in 28 % of cases (n = 8) the deviation of the mechanical axis was up to 1° from the planned one.Discussion Neither technical difficulties nor complications inherent to RoTKA were found. According to the results of VAS, WOMAC and FJS‑12 questionnaires, and the assessment of the range of motion, a positive dynamics was observed. According to the results of tele-roentgenograms, there was alignment of the limb axis and the accuracy of the position of the endoprosthesis components.Conclusion The study of this technology has demonstrated safety, accuracy of alignment of the mechanical axis, validity of indications and contraindications, and stable early clinical results.

Wedgeless V-Shaped Osteotomy of the Distal Medial Femur with Locking Plate Fixation for Correction of Genu Valgum in Adolescents and Young Adults.

Genu valgum is a common disorder affecting adolescents and young adults. Treatment of this disorder requires restoration of normal mechanical axis alignment and joint orientation, for which it is important to assess whether the deformity arises from the distal femur, knee joint, or proximal tibia. Most commonly, the deformity originates from the distal femur, and various osteotomies of the distal femur have been described1-6. The presently described wedgeless V-shaped osteotomy7,8 is a good option among the various alternative procedures listed below. The anesthetized patient is placed in the supine position on a radiolucent operating table. A bolster is placed beneath the knee to relax the posterior structures. A medial longitudinal skin incision is made that extends from the level of the medial joint line to 5 cm proximal to the adductor tubercle. The vastus medialis is identified and elevated anteriorly by detaching it from its distal and posterior aspects. The leash of vessels underneath the vastus medialis is identified, and the apex of the V-shaped osteotomy is kept just proximal to it. The anterior arm of the V is kept longer than the posterior one, both of them are kept perpendicular to each other, and the apex of the V is made to point distally. The osteotomy is performed on the medial cortex with use of an oscillating saw or multiple drill holes that are then connected using a thin osteotome. Care is taken not to utilize a saw or drill on the lateral cortex. A gentle valgus thrust is applied to break the lateral cortex without periosteal disruption. The apex of the V osteotomy on the proximal fragment is trimmed, and the deformity is corrected with varus force. The osteotomy site is stabilized with use of an anatomically contoured distal medial femoral locking plate or a medial proximal tibial L-shaped buttress plate (of the contralateral side). The implant position is verified under a C-arm image intensifier. The wound is closed in layers over a suction drain in a standard manner. Various types of corrective osteotomies of the distal femur have been described in the literature, including the lateral opening wedge, medial closing wedge, dome, and spike osteotomies1-6. All of these procedures have certain limitations and shortcomings. The wedgeless V-shaped osteotomy is another described procedure that is inherently stable7,8. It is a safe procedure and yields good clinical outcomes8,9. The posterior arm of the V-shaped osteotomy is kept smaller than the anterior arm. The proximal cortical bone is allowed to dig into the cancellous bone of the wider distal metaphysis during deformity correction. Trimming the apex of proximal bone end after making the osteotomy facilitates the process. In a study of 46 patients with a mean age of 16.9 years (range, 15 years to 23 years), Gupta et al.8 reported that the mean radiographic tibiofemoral angle improved from 22.2° (range, 16° to 29°) preoperatively to 5.1° (range, 0° to 10°) postoperatively (p < 0.001). Similarly, the mean lateral distal femoral angle improved from 79.2° preoperatively to 89.1° postoperatively (p < 0.001) and the mean mechanical axis deviation improved from 19.6 mm preoperatively to 3.7 mm postoperatively (p < 0.001). A total of 44 of 46 cases had an excellent functional outcome, with the other 2 having good outcomes. None of the patients in the study had an unsatisfactory outcome. It is important to keep the whole lower limb accessible to the image intensifier intraoperatively.Identification of the leash of vessels underneath the vastus medialis is important to decide the level of the osteotomy.It is important to preserve the periosteal sleeve on the lateral aspect of the femur. CORA = center of rotation of angulationECG = electrocardiogramLDFA = lateral distal femoral angleMAD = mechanical axis deviationMPTA = medial proximal tibial angle.

Mid-Term Survivorship, Radiographic and Functional Outcomes of Robotic-Assisted Unicompartmental Knee Arthroplasty.

The use of robotic-arm assistance for medial unicompartmental knee arthroplasty (RAUKA) has become an area of interest to overcome technical challenges, improve accuracy, and optimize patient outcomes. Due to the rise in osteoarthritis (OA) and robotic assistance, well-powered long-term studies are warranted. The aim of this study was to analyze midterm survivorship, radiographic changes, range of motion (ROM), and patient-reported outcome measurements (PROMs) of RAUKA. Patients who underwent RAUKA for medial compartmental OA were identified from April 2009 to May 2014. The query yielded 162 knees with a mean follow up of 6.5 years. Primary endpoints were to compare survivorship, final mechanical axis alignment, radiographic changes, mean ROM, and changes to the following PROMs: Knee Society Score (KSS), International Knee Documentation Committee (IKDC), and Oxford Knee Score (OKS). Statistical analyses were primarily descriptive. A p-value less than 0.05 was considered statistically significant. There were no revisions of the primary implant, one case required exchange of polyethylene bearing and debridement for deep infection, and five cases required additional surgical intervention with implant retention. Overall survivorship was 100%. Radiographic assessment demonstrated no mechanical loosening or osteolysis surrounding the implant. Mean ROM was 3 to 121.9º. Patients demonstrated a mean functional KSS of 78.55, IKDC of 78.22, and OKS of 43.94. The study supports excellent mid-term outcomes in patients undergoing RAUKA for medial compartment OA. Longer term follow-up studies are necessary to determine the efficacy of this technology for patients undergoing RAUKA for medial compartment OA.

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.

Radiological Evaluation of OrthAlign-A Novel Handheld Navigation System used in Total Knee Replacement.

The goal of this research is to determine how well OrthAlign, a novel portable navigation system for total knee replacement, helps surgeons make accurate incisions. When comparing OrthoAlign, a portable accelerometer-based technique, to the gold standard of extramedullary jigs, the results are promising. This study aimed to evaluate the accuracy of distal femoral and proximal tibial cuts in total knee arthroplasty. This research analyzed data from a prospective cohort study. Participants in the study all had resections of the proximal tibia and distal femur using the OrthAlign portable navigations device. Total knee arthroplasty (TKA) patients throughout the same time period who used traditional medullary alignment jigs were included as a control group. Before and after surgery, full-length standing stitch radiographs of the patient's lower limbs were acquired so that the alignment of their knees could be assessed. In the mechanical alignment exam done following the surgery, the OrthAlign group performed substantially better than the control group, although the difference was not statistically significant. Patients treated with OrthoAlign had considerably improved alignment of the tibial components in the coronal plane compared to those treated manually. When comparing the OrthAlign cohort to the conventional cohort, average sagittal plane alignment of tibial components was significantly different. Yet, when comparing femoral alignment after surgery, neither the mechanical alignment nor the OrthAlign groups fared better. Furthermore, there was no statistically significant difference between the two groups when it comes to the occurrence of outliers with postoperative mechanical axis alignment >3 degrees or tibial alignment in the coronal plane >2 degrees. Compared to OrthAlign, conventional alignment methods resulted in a higher percentage of postoperative tibial alignment in the sagittal plane (greater than 2 degrees). Patients whose femurs were misaligned by more than 2 degrees after surgery favored the OrthAlign method, albeit this was not statistically different from the control group. There was a significant reduction in tourniquet time for patients using OrthoAlign compared to those using mechanical alignment devices.

Clinical outcomes of Schatzker type II tibial plateau fractures using joint depression morphology: A cross-sectional study.

Tibial plateau fracture is a common intra-articular fracture caused by axial compression and Varus or Valgus force. This study aimed at the relationship between Luo classification morphology of tibial plateau fractures with clinical outcomes and surgical complications. The cross-sectional study was conducted on patients with Schatzker type II tibial plateau fracture who underwent surgery between May 2018 and January 2021. Clinical outcomes were measured by the AKSS, VAS, Lysholm score, alignment, and ROM. A total of 65 patients with a mean age of 36.38 years were enrolled. There was a significant difference in AKSS (p=0.001), VAS score (p=0.011), and mechanical axis alignment (p=0.037) between the groups by pre-operative joint depression depth below and above 10 millimeters. The higher pre-operative or post- operative size of joint depression depth in patients with Schatzker type II tibial plateau fractures was associated with poor outcomes, more pain, and malalignment. A higher surface area of joint depression was associated with a lower clinical outcome score and more pain.

Mid-Term Survivorship, Radiographic and Functional Outcomes of Robotic-Assisted Unicompartmental Knee Arthroplasty.

The use of robotic-arm assistance for medial unicompartmental knee arthroplasty (RAUKA) has become an area of interest to overcome technical challenges, improve accuracy, and optimize patient outcomes. Due to the rise in osteoarthritis (OA) and robotic assistance, well-powered long-term studies are warranted. The aim of this study was to analyze midterm survivorship, radiographic changes, range of motion (ROM), and patient-reported outcome measurements (PROMs) of RAUKA. Patients who underwent RAUKA for medial compartmental OA were identified from April 2009 to May 2014. The query yielded 162 knees with a mean follow up of 6.5 years. Primary endpoints were to compare survivorship, final mechanical axis alignment, radiographic changes, mean ROM, and changes to the following PROMs: Knee Society Score (KSS), International Knee Documentation Committee (IKDC), and Oxford Knee Score (OKS). Statistical analyses were primarily descriptive. A p-value less than 0.05 was considered statistically significant. There were no revisions of the primary implant, one case required exchange of polyethylene bearing and debridement for deep infection, and five cases required additional surgical intervention with implant retention. Overall survivorship was 100%. Radiographic assessment demonstrated no mechanical loosening or osteolysis surrounding the implant. Mean ROM was 3 to 121.9º. Patients demonstrated a mean functional KSS of 78.55, IKDC of 78.22, and OKS of 43.94. The study supports excellent mid-term outcomes in patients undergoing RAUKA for medial compartment OA. Longer term follow-up studies are necessary to determine the efficacy of this technology for patients undergoing RAUKA for medial compartment OA.

A retrospective study of articular surface mounting computer-assisted total knee arthroplasty in alignment, knee function, and survival

Background Hong Kong Chinese exhibits a greater varus lower limb mechanical axis and coronal bowing when compared to Caucasians. This anatomical difference may affect the accuracy of bone cuts in total knee arthroplasty (TKA) using western anatomy-based intramedullary TKA cutting jigs. Use of computer navigation may avoid suboptimal cuts due to altered anatomy. This is the first study evaluating clinical function, radiological alignment and long-term survival of computer-assisted TKA amongst Hong Kong Chinese patients. Methods Retrospective study comparing articular surface mounting computer-assisted TKA (ASM-CATKA) and conventional TKA performed in a single centre from 2008 to 2010. Patients were followed up for ​assessment of clinical parameters including range of motion, Knee Society Knee score, and radiological parameters such as limb alignment, component alignment, and survival. Results Seventy-five patients were included in this study. Baseline clinical and radiological data were similar between groups. The computer-navigated group had superior radiological mechanical alignment ( p &lt; 0.001), tibial component alignment ( p = 0.016) and femoral component alignment ( p &lt; 0.01) when compared to conventional TKA. There were no differences in knee scores ( p = 0.488), range of motion ( p = 0.432) and survival at 117 months ( p = 0.986) between the two groups. Conclusion This retrospective study showed that ASM-CATKA was more accurate in achieving neutral mechanical axis and component alignment amongst Hong Kong Chinese. Clinical outcomes and implant survival were comparable.

Рандомизированное двойное контролируемое сравнительное исследование точности выравнивания механической оси нижней конечности

The objectives of total knee arthroplasty (TKA) are pain relief, increased range of motion, and alignment of the mechanical axis of the limb. The aim of this study was to investigate the accuracy of alignment of the mechanical axis of the lower limb during robotic primary TKA in comparison with computer navigation and manual technique. A prospective double controlled study of 99 patients randomized into groups was performed. Group A (main) included 29 patients who underwent robot-assisted TKA, group B (control) included 32 patients who underwent standard endoprosthetic technique, and group C (control) included 31 patients who underwent computer-navigated arthroplasty. Telerentgenogram and computed tomographic examination were performed, and the accuracy of mechanical alignment of the limb axis was analyzed. In group A, the accuracy of the mechanical axis is up to ± 1° — 72%, from ±1º to ±3º — 28%, in group B up to ± 1° — 30%, from ± 1° to ±3° — 55%, and more than ± 3° — 15%, in group C up to ± 1° — 45%, from ± 1º to ±3º — 48%, more than 3º — 7%. The accuracy of the alignment of the mechanical axis of the limb with robotic TKA up to ±1° is 72%, statistically significantly exceeds manual technique (30%) and computer navigation (45%), which opens up new prospects in the survival of endoprostheses.

Functional alignment achieves a more balanced total knee arthroplasty than either mechanical alignment or kinematic alignment prior to soft tissue releases

PurposeTotal knee arthroplasty with functional alignment uses pre-resection balancing to determine component position within the soft tissue envelope to achieve balance and restoration of native joint obliquity. The purpose of this study was to assess the balance achievable with a mechanical axis alignment and kinematic axis alignment plan, and the subsequent balance achievable after adjustment of the component position to functional alignment.MethodsA prospective cohort of 300 knees undergoing cruciate retaining total knee arthroplasty were included in this study. Of these, 130 were initially planned with mechanical alignment (MA) and 170 with kinematic alignment (KA). Maximal stressed virtual gaps were collected using an optical tracking software system. The gaps were measured medially and laterally in flexion and extension. Following assessment of balance, implant position was adjusted to balance the soft tissues in functional alignment (FA) and the maximal gaps reassessed. Gaps were considered to be balanced when within 2 mm of equality. Incidence of balance within each cohort was compared to independent samples proportions test.ResultsFunctional alignment obtained significantly better balance in extension, medially and overall than both MA and KA alignment without soft tissue release (p < 0.001). Overall balance was observed in 97% of FA knees, 73% of KA knees and in 55% of MA knees. The difference between KA and MA was also significant (p = 0.002). Whilst there was no difference observed in balanced achieved or limb alignment when FA was planned with either MA or KA, the joint line obliquity was maintained with an initial KA plan.ConclusionFunctional alignment more consistently achieves a balanced total knee arthroplasty than either mechanical alignment or kinematic alignment prior to undertaking soft tissue release. Utilising an individualised KA plan allows FA to best achieve the stated goals of maintaining joint line plane and obliquity.Level of evidenceLevel III: retrospective cohort study.

An Early-stage Comparison of Functional Outcomes Following Robotic-assisted Versus Conventional Total Knee Arthroplasty: A Systematic Review and Meta-analysis

Introduction: Conventional total knee arthroplasty (cTKA) is used to relieve pain and restore knee function and stability. Robotic-assisted TKA (rTKA) was introduced to improve the placement of surgical implants, decrease postoperative complications, and improve implant longevity. To date, studies examining functional outcomes and patient-reported pain between rTKA and cTKA in the short-term postoperative period are limited, and a meta-analysis of such early-stage outcomes has yet to be accomplished. Our study aims to evaluate the differences in function, alignment, and pain between rTKA and cTKA within 6 months postoperatively through meta-analysis. Materials and Methods: A literature search of the PubMed and Cochrane electronic databases was performed in December 2021 with Medical Subject Headings and search terms limited to “knee replacement,” “knee arthroplasty,” and “robotic knee surgery.” Subsequent analysis was conducted on all retrieved studies written in English. Results: Thirteen clinical studies were considered for systematic review, of which nine were included in meta-analysis. 1,336 cases of TKA were analyzed: RTKA (n = 618) and cTKA (n = 718). There were no significant differences between rTKA and cTKA in range of motion (mean difference,-0.08°; P = 0.55), functional score of the Knee Society Score (mean difference, 0.04; P = 0.78), oxford knee score (mean difference, −0.04; P = 0.81), and Functional score of the western ontario and mcmaster universities osteoarthritis index (WOMAC-F) (mean difference, −0.42; P = 0.41). There were no significant pain differences in Short Form Health Survey Bodily Pain (mean difference, −0.08; P = 0.64) and pain score of the WOMAC (WOMAC-P) (mean difference, −0.25; P = 0.47). However, rTKA subjects achieved more accurate mechanical axis alignment than cTKA subjects (mean difference, −0.50°; P &lt; 0.01). Conclusion: Although limb alignment correction is more accurate in rTKA than cTKA, functional and pain metrics are comparable between the two procedures within 6 months’ follow-up, suggesting no added clinical benefits for rTKA versus cTKA.

What Is the Alignment and Balance of a Total Knee Arthroplasty Performed Using a Calipered Kinematic Alignment Technique?

We simulated calipered kinematic alignment total knee arthroplasty (cKATKA) using alignment data and ligament tensions acquired during 607 consecutive robotic-assisted TKAs performed using a dynamic ligament tensor. The distal femur was resected parallel to the native joint line accounting for cartilage loss. The proximal tibial resection necessary to achieve extension gap balance was calculated for each knee. Similarly, symmetric posterior condylar resections prescribed by this method were simulated and the tibial resection needed to achieve a balanced flexion gap calculated. Finally, the resultant limb alignment and degree of joint balance in both flexion and extension of each knee were determined and categorized according to the preoperative knee alignment. Increasing preoperative varus deformity required a greater tibial varus cut to achieve a balanced extension gap (P < .0001). There was no correlation between tibial varus angle and flexion gap balance (P > .1). For mild varus deformities 81% and 95% of knees could be balanced and have an overall limb alignment within 3° and 5° from the mechanical axis respectively. For knees with moderate-severe varus, only 37% and 74% could be balanced within these alignment boundaries (P < .01). Overall, 95% of these simulated knees could be balanced with an overall alignment within 0° ± 5°. However, 50% of the simulated TKAs had looser medial gaps in flexion compared to the lateral gap. Application of the cKATKA method can yield TKAs within 0° ± 5° of mechanical axis alignment by simply adjusting the proximal tibial resection without ligament releases. However, an undesirable flexion gap balance was predicted in nearly 50% of the TKAs.

A Study of Surgical Accuracy with X-Ray-Based Patient-Specific Instrument (X3DPSI®) vs Conventional Instrument in Total Knee Arthroplasty Surgeries.

Patient-specific instruments (PSI) have been shown to be a good solution in getting accurate bone cuts in total knee arthroplasty (TKA) in many studies. However, the need for an extra CT/MRI makes the existing PSI method costly and unsafe. X-ray-based PSI can solve these problems, if proven to be accurate. The purpose of this study was to introduce a novel method to measure the performance of X-ray to 3D-based PSI (X3DPSI ® ) in achieving planned bone cuts by comparing with conventional instruments (CI). This was a prospective study of a total of ten patients undergoing TKA surgery. Preoperative full length lower limb scanogram was done with specialized calibration strap-on marker to develop X3DPSI ® which was used intraoperatively for the placement of guiding pins for the cutting jig. Similarly, intraoperative guide pins were placed using CI also. Calibrated intraoperative X-ray images, in AP and LAT view, were taken while the cutting-block guiding pins were placed on the distal femur and proximal tibia. These X-ray images were used to calculate the cutting plane alignments for femur and tibia and to simulate the postoperative hip-knee-ankle (HKA) angle and MAD (mechanical axis deviation), in a virtual Tabplan3D environment for both the methods. The results showed that there was a significant difference between the two methods in terms of femoral cutting plane angles and in terms of the HKA angles and MAD. There was no significant difference in the tibial cutting plane angles in the coronal plane. The mechanical axis alignment achieved based on the virtual cuts made using the X3DPSI ® was significantly better than the alignment achieved based on the cuts made using the CI, in terms of both HKA and MAD. This novel method of X-ray-based PSI is a low-cost alternative to CT/MRI-based PSI if found to be accurate in future planned studies.

Functional Outcome Based on Mechanical Axis Alignment Following Total Knee Arthroplasty.

BackgroundTotal knee arthroplasty (TKA) is the most commonly performed and highly successful surgical intervention for end-stage osteoarthritis of the knee, and it offers patients pain relief, functional recovery, and improved quality of life. The success of knee arthroplasty depends on various factors such as precise surgical technique, alignment of the limb and components, patient selection, and compliance with rehabilitation. Mechanical alignment of the lower limb has been considered an important factor in planning and assessing the success of TKA. Optimal alignment remains a matter of controversy; hence, it is paramount to assess the alignment and functional outcomes.Aim and objectiveThis study aimed to evaluate the reliability of conventional instrumentation in imparting the intended femoral and tibial coronal alignment, as well as study the functional outcome among the neutrally aligned outliers with respect to the mechanical axis of the lower limb using standing long-leg radiographs.MethodologyThis is a prospective, hospital-based, observational study that was conducted on 60 knees in 42 patients with primary osteoarthritis of the knee joint in the department of orthopedics, Satguru Partap Singh (SPS) Hospitals, Ludhiana. Patients undergoing total knee arthroplasty who fulfilled the inclusion criteria were included in our study and evaluated using Knee Society Score and knee flexion range at periodic follow-up till six months. Preoperative and postoperative standing long-leg radiographs were done for all the patients, and their functional outcome was compared among inliers and outliers.ResultsOut of these 60 total knee arthroplasties, 18 patients were operated on both knees, and 24 patients were operated on a single knee. There were 25 female patients and 17 male patients. The mean for pre-operative mechanical axis alignment angle was 11.88° ± 5.63° with a range from -3° to 27°, which changed to 2.90° ± 1.59° with a range from 0° to 8° at six months follow-up. It was observed that 42 of the knees were in the inliers, and the remaining 18 knees were in the outliers group. On comparison among inliers and outliers, we found that the mean range of motion was 108.29° ± 4.82° for the inliers group and 106.11° ± 4.04° for the outliers group (p = 0.091), depicting non-significant statistical comparison. Mean Knee Society Score values in inliers and outliers group were 152.45 ± 5.33 and 151.61 ± 3.55, respectively (p = 0.740), showing no statistical significance.ConclusionAt six months follow-up, there is no difference in the knee range of motion and Knee Society Scores between mechanical axis inliers and outliers. Thus, we conclude that although every knee arthroplasty is intended to have neutral mechanical alignment, there is no effect of mild mechanical axis malalignment on functional outcome following total knee arthroplasty in the short term.

HURWA robotic-assisted total knee arthroplasty improves component positioning and alignment - A prospective randomized and multicenter study.

BackgroundThe objective of this study was to compare the radiologic and clinical outcomes of HURWA robotic-assisted total knee arthroplasty (TKA) to those of conventional TKA.MethodsA total of 150 patients were randomized into two groups – 73 and 77 patients underwent robotic-assisted TKA and conventional TKA, respectively. Preoperative and postoperative Western Ontario McMaster University Osteoarthritis Index (WOMAC) score, Hospital for Special Surgery (HSS) score, 36-item Short Form Health Survey (SF-36) score, Knee Society Score (KSS) and range of motion (ROM) were obtained and compared between these two groups. The preoperative and postoperative hip-knee-ankle (HKA) angle and the rate of HKA≤3° in the two groups were also compared.ResultsThe postoperative mean HKA angle was 1.801° ​± ​1.608° of varus for the robotic-assisted TKA group and 3.017° ​± ​2.735° of varus for the conventional TKA group; these values were significantly different. The alignment rate for mechanical axis lower than 3° in the robotic-assisted TKA group and the conventional TKA group were 81.2% and 63.5%, respectively. Patients undergone robotic-assisted TKA or conventional TKA had similarly improved knee flexion and functional recovery reflected by WOMAC score, HSS score, SF-36 score and KSS.ConclusionHURWA robotic-assisted TKA is a safe and effective, resulting in better alignment for mechanical axis than conventional TKA. The improvement in knee flexion and functional recovery after HURWA robotic-assisted TKA were similar to those after conventional TKA. However, longer follow-up is needed to determine whether the improved alignment of mechanical axis will produce better long-term clinical outcomes.The translational potential of this articleRecently, the robotic-assisted TKA system has been introduced to clinical practice for TKA. Several robotic-assisted TKA systems, including CASPAR, Tsolution, ROSA, ROBODOC and Mako, have been implemented into clinical application.However, the clinical application of these robotic systems was limited due to their technical complexity, insufficient versatility and increased operative time. Until now, there are still no robotic-assisted TKA systems approved by the National Medical Products Administration of China. Therefore, more robotic-assisted TKA systems need to be designed and improved, particularly in China. Through our randomized, multicenter, single blind and parallel controlled trial, we showed that HURWA robot-assisted TKA system is a safe and effective system for TKA, which had improved knee flexion.