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Introduction: Knee alignment significantly impacts the outcome of total knee arthroplasty (TKA). Understanding patient perceptions of their knee alignment in relation to objective measurements is essential to ensure optimal surgical outcomes and to meet patients’ expectations. This study reports patients’ perception of pre- and postoperative knee alignment in relation to radiographic alignment measurements. Materials and methods: The study included 141 patients with primary osteoarthritis of the knee (mean age: 65.4 years, BMI: 30.8). Patients categorized their knee alignment before and after surgery using a picture-based rating scale: very bow-legged (> 10° varus), bow-legged (2.1–10° varus), straight (2° varus to 2° valgus), knock-kneed (2.1–10° valgus), and very knock-kneed (> 10° valgus). Hip-to-ankle films were performed to compared actual knee alignment with patients’ assessments retrospectively. Results: Preoperatively, 15.1% of patients with severe varus, 55.6% with varus, and 86.7% with neutral alignment perceived their knees as straight. None of the patients with valgus or severe valgus alignment considered their knees as straight. Overall, 40.2% of patients with radiographic varus alignment classified their knees as straight, while nobody with valgus alignment did. Postoperatively patients with preoperative varus considered their knees as straight with an average of 1.8 ± 1.7 deg. mechanical varus alignment, while patients with preoperative valgus alignment considered their knees straight with an average of 0.4 ± 0.9 deg. mechanical valgus alignment. Conclusion: Patients predominantly desire a straight knee postoperatively, however, most patients tend to perceive some varus alignment as straight. This is most common in patients with up to 5 degrees of varus deformity and suggests that a restricted or inverse kinematic alignment with up to 5 degrees of varus can meet the expectations of most patients. In contrast, patients with valgus deformity are sensitive to any remaining valgus deformity and leaving the knees in more than 2 deg. of valgus will unlikely satisfy the patients’ overall desire for a straight knee after surgery. [ABSTRACT FROM AUTHOR]

Purpose: Achieving precise postoperative alignment is critical for the long-term success of total knee arthroplasty (TKA). Long-leg standing radiograph (LLR) at 6 weeks post-op is the gold standard for assessing alignment, but its reliance on weight-bearing and positioning makes it less practical in the early postoperative period. Supine computed tomography scanogram (CTS) offers a potential alternative. This study compares CTS and LLR in patients undergoing TKA with patient-specific valgus correction angles (VCA). Methods: A prospective study of 108 knees from 57 patients undergoing primary TKA was conducted. CTS was performed on postoperative day three in a supine non-weight-bearing position, and LLR at six weeks in an upright standing position. Coronal alignment was assessed using hip-knee-ankle angle (HKA) and compared using Bland-Altman plots, paired-samples t-tests, and Cohen’s d. Results: CTS showed 57% of knees were within 3° of neutral alignment, while LLR showed 61%. The mean difference between modalities was 0.52° (SD, 3.56°; p = 0.07). Inter-observer reliability was excellent for both CTS and LLR (all ICCs > 0.9). Conclusion: While CTS provides a useful alternative for early postoperative alignment assessment—particularly in situations where a standing LLR is not feasible—the observed variability suggests that LLR remains the more reliable modality when precise alignment is critical. Surgeons should therefore consider CTS as an adjunct tool for early decision-making or non-ambulatory patients in the immediate postoperative setting. Level of evidence: Level II, Prospective Comparative Study. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess whether kinematic alignment (KA) outperforms mechanical alignment (MA) in restoring patellar tracking to native patterns by using a clustering algorithm. Methods: Twenty cadavers (40 knees) were evaluated. For each cadaver, one knee was randomly assigned to KA and the other to MA. KA total knee arthroplasty (TKA) procedures were performed using a caliper‐verified technique, while MA TKA procedures utilized a measured resection technique. Subsequently, all specimens were mounted on a customized knee‐testing system, and patellar tracking was measured using a motion analysis system. All patellar tracking data were clustered using the density‐based spatial clustering of applications with noise algorithm. Differences in patellar tracking patterns and the restoration of native patellar tracking were compared between the two alignment strategies. Results: Patellar tracking patterns following KA were considerably different from MA. Pre‐ and post‐TKA patellar tracking patterns following MA were grouped into separate clusters, whereas a substantial proportion of patellar tracking patterns following KA were grouped into the pre‐TKA dominant cluster. Compared to MA, a greater proportion of patellar tracking patterns following KA showed similar patterns to native knees (p < 0.05) and more patellar tracking patterns following KA paired with preoperative patterns (p < 0.01). Conclusion: KA restored native patellar tracking patterns more closely compared to MA. Level of Evidence: Level I, therapeutic study. [ABSTRACT FROM AUTHOR]

Mechanical alignment after total knee arthroplasty (TKA) is still widely used in the surgical community, but the alignment finally obtained by conventional techniques remains uncertain. The recent Coronal Plane Alignment of the Knee (CPAK) classification distinguishes 9 knee phenotypes according to constitutional alignment and joint line obliquity (JLO). The aim of this study was to assess the phenotypes of osteoarthritic patients before and after TKA using mechanical alignment and to analyze the influence of CPAK restoration on functional outcomes. This retrospective multicenter study included 178 TKAs with a minimum follow-up of 2 years. Patients were operated on using a conventional technique with the goal of neutral mechanical alignment. The CPAK grade (1 to 9), considering the arithmetic Hip-Knee-Ankle angle (aHKA) and the JLO, was determined before and after TKA. Functional results were assessed using the following patient-reported outcome measures: Knee Injury and Osteoarthritis Outcome Score, the Simple Knee Value, and the Forgotten Joint Score. A true neutral mechanical alignment was obtained in only 37.1%. Isolated restoration of JLO was found in 31.4%, and isolated restoration of the aHKA in 44.9%. Exact restoration of the CPAK phenotype was found in 14.6%. Restoration of the CPAK grade was associated with an improvement in the "daily living": 79.2 ± 5.3 versus 62.5 ± 2.3 (R2 = 0.05, P <.05) and "Quality of life" Knee Injury and Osteoarthritis Outcome Score subscales: 73.8 ± 5.0 versus 62.9 ± 2.2 (R2 = 0.02, P <.05). This study shows that few neutral mechanical alignments are finally obtained after TKA by conventional technique. A major number of patients present a postoperative modification of their constitutional phenotype. Functional results at 2 years of follow-up appear to be improved by the restoration of the CPAK phenotype, JLO, and aHKA. III, Retrospective Cohort Study. [ABSTRACT FROM AUTHOR]

Background/objective: This study aimed to clarify the kinematics of bi-cruciate-retaining (BCR) total knee arthroplasty (TKA) by comparing the mechanical alignment (MA) and functional alignment (FA) methods and to evaluate differences between the two alignment methods. Methods: The in vivo kinematics of 20 MA TKA and 20 FA TKA knees were investigated under fluoroscopy during squatting using a two-to three-dimensional registration technique. Accordingly, knee flexion angle, axial rotational angle, varus–valgus angle, anteroposterior translation of the medial and lateral low contact points of the femoral component relative to the tibial component and kinematic pathway were evaluated. Results: No difference in the knee flexion angle was observed between the MA and FA TKA groups. Femoral external rotation was observed in both groups and no significant difference was observed. Significant varus alignment from extension to early flexion range was observed in the FA TKA group. The posterior translation of the medial side was smaller in the FA TKA group than in the MA TKA group. Conversely, no significant difference in the anteroposterior translation of the lateral side was observed. In the kinematic pathway, a medial pivot motion from 0° to 20° of flexion and a lateral pivot motion beyond 20° of flexion were observed in both groups. Conclusion: During squatting in BCR TKA, the FA TKA group significantly showed varus alignment and smaller posterior translation of the medial side than the MA TKA group from extension to early flexion range.

Background and Objectives: The Coronal Plane Alignment of the Knee (CPAK) classification is a pragmatic distribution of nine phenotypes for coronal knee alignment that can be used on healthy and arthritic knees. Our study aimed to describe the CPAK distributions in a Spanish southeast osteoarthritic population and compare them to other populations' published alignment distributions. Method and Materials: Full-leg standing X-rays of the lower limb from 528 cases originating from the so-called Vega Alta del Segura (southeast of the Iberian Peninsula) were retrospectively analysed. We measured the mechanical hip–knee–ankle, lateral distal femoral, and medial proximal tibial angles. We calculated the arithmetic hip–knee–ankle angle and the joint line obliquity to classify each case according to the criteria of the CPAK classification. Results: Based on the aHKA result, 59.1% of the cases were varus (less than −2°), 32.7% were neutral (0° ± 2°), and 8.2% were valgus (greater than +2°). Based on the JLO result, 56.7% of the cases had a distal apex (less than 177°), 39.9% had a neutral apex (180° ± 3°), and 3.4% had a proximal apex (greater than 183°). The most common CPAK distribution in our Spanish southeast osteoarthritic population was type I (30.7%), followed by type IV (25.9%), type II (21%), type V (11.2%), type III (5%), type VI (2.8%), type VII (2.4%), type VIII (0.6%), and type IX (0.4%). Conclusions: We described the distribution according to the CPAK classification in a sample of the osteoarthritic population from southeastern Spain. In our sample, more than 75% of the patients were classified as type I, II, and IV. [ABSTRACT FROM AUTHOR]

Introduction: In total knee arthroplasty (TKA), suboptimal restoration of joint line obliquity (JLO) and joint line height (JLH) may lead to diminished implant longevity, increased risk of complications, and reduced patient reported outcomes. The primary objective of this study is to determine whether restricted kinematic alignment (rKA) leads to improved restoration of JLO and JLH compared to mechanical alignment (MA) in TKA. Materials and Methods: This retrospective study assessed patients who underwent single implant design TKA for primary osteoarthritis, either MA with manual instrumentation or rKA assisted with imageless navigation robotic arm TKA. Pre- and post-operative long standing AP X-ray imaging were used to measure JLO formed between the proximal tibial joint line and the floor. JLH was measured as the distance from the femoral articular surface to the adductor tubercle. Results: Overall, 200 patients (100 patients in each group) were included. Demographics between the two groups including age, sex, ASA, laterality, and BMI did not significantly differ. Distribution of KL osteoarthritis classification was similar between the groups. For the MA group, pre- to post-operative JLO significantly changed (2.94° vs. 2.31°, p = 0.004). No significant changes were found between pre- and post-operative JLH (40.6 mm vs. 40.6 mm, p = 0.89). For the rKA group, no significant changes were found between pre- and post-operative JLO (2.43° vs. 2.30°, p = 0.57). Additionally, no significant changes were found between pre- and post-operative JLH (41.2 mm vs. 42.4 mm, p = 0.17). Pre- to post-operative JLO alteration was five times higher in the MA group compared to the rKA group, although this comparison between groups did not reach statistical significance (p = 0.09). Conclusion: rKA-TKA results in high restoration accuracy of JLO and JLH, and demonstrates less pre- and post-operative JLO alteration compared to MA-TKA. With risen interest in joint line restoration accuracy with kinematic alignment, these findings suggest potential advantages compared to MA. Future investigation is needed to correlate between joint line restoration accuracy achieved by rKA and enhanced implant longevity, reduced risk of post-operative complications, and heightened patient satisfaction. [ABSTRACT FROM AUTHOR]

Kinematic and mechanical alignment outcomes in total knee arthroplasty remain controversial. This study compared the clinical and radiological outcomes of total knee arthroplasty using kinematic and mechanical alignments. We systematically searched PubMed, EMBASE, Web of Science, and Cochrane Library databases for randomized controlled trials and cohort studies published before November 2022. The data of interest were extracted and analyzed using Review Manager V.5.4. Nineteen randomized controlled trials and cohort studies involving 880 kinematic alignment total knee arthroplasties and 965 mechanical alignment total knee arthroplasties were included. In this meta-analysis, the kinematic alignment group achieved better knee joint function scores, including the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score, and Knee Society Score, and better flexion angles. No statistical differences were detected in the Western Ontario and McMaster Universities Osteoarthritis Index, extension angle, Forgotten Joint Score, European Quality of Life five-dimension measure, hip–knee–ankle angle, or complications between the kinematic and mechanical alignment groups. This meta-analysis indicated that kinematic alignment total knee arthroplasty provides clinical benefits in terms of the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score, Knee Society Score (knee), Knee Society Score (function), and better flexion angles. In addition, kinematic alignment total knee arthroplasty led to similar clinical outcomes as mechanical alignment total knee arthroplasty without increasing complications. http://www.crd.york.ac.uk/PROSPERO/CRD42022373227. [ABSTRACT FROM AUTHOR]

Achieving optimal alignment in total knee arthroplasty (TKA) is a critical factor in ensuring optimal outcomes and long-term implant survival. Traditionally, mechanical alignment has been favored to achieve neutral postoperative joint alignment. However, contemporary approaches, such as kinematic alignments and hybrid techniques including adjusted mechanical, restricted kinematic, inverse kinematic, and functional alignments, are gaining attention for their ability to restore native joint kinematics and anatomical alignment, potentially leading to enhanced functional outcomes and greater patient satisfaction. The ongoing debate on optimal alignment strategies considers the following factors: long-term implant durability, functional improvement, and resolution of individual anatomical variations. Furthermore, advancements of computer-navigated and robotic-assisted surgery have augmented the precision in implant positioning and objective measurements of soft tissue balance. Despite ongoing debates on balancing implant longevity and functional outcomes, there is an increasing advocacy for personalized alignment strategies that are tailored to individual anatomical variations. This review evaluates the spectrum of various alignment techniques in TKA, including mechanical alignment, patient-specific kinematic approaches, and emerging hybrid methods. Each technique is scrutinized based on its fundamental principles, procedural techniques, inherent advantages, and potential limitations, while identifying significant clinical gaps that underscore the need for further investigation. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the clinical results of kinematic alignment (KA) with those of mechanical alignment (MA) in single-stage bilateral total knee arthroplasty. In this double-blinded randomized controlled trial, 65 patients who had bilateral knee osteoarthritis underwent simultaneous bilateral total knee arthroplasty. One knee was randomly selected to be operated on with the calipered-KA technique and the other with MA. The participants were assessed via the Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index questionnaire, and visual analog scale before the surgery and the same plus the Forgotten Joint Score at their last follow-up visit, 2 years postoperatively. Maximum knee flexion and the time reaching maximum knee flexion, named the recovery time, were also recorded. Hip-knee-ankle angle, medial proximal tibial angle, and lateral distal femoral angle were measured before and after the surgery using 3-joint-view radiographs. At 2 years, there were significant differences between the KA and MA techniques in terms of duration of surgery, recovery time, and final Western Ontario and McMaster Universities Osteoarthritis Index, Forgotten Joint Score, and maximum flexion range in favor of KA (P <.05), but no significant difference in visual analog scale score or Oxford Knee Score. In patients who have a preferred knee, the KA knee was preferred over the MA knee by most patients. No prosthetic failure or revision was reported in either group. The KA technique yields acceptable functional outcomes compared to the MA technique. The KA technique was associated with a shorter surgery time, a faster recovery time, and higher patient satisfaction in 2-year follow-ups. Larger multicenter studies with longer follow-ups are warranted to confirm these findings. I. [ABSTRACT FROM AUTHOR]

PurposeBecause different targets are used for internal-external rotation, an asymmetric baseplate designed for mechanical alignment may lead to under-coverage and concomitant posterior rim loading in the lateral compartment following unrestricted kinematic alignment (KA) TKA. Recognizing that such loading can lead to premature wear and/or subsidence, our aim was to determine the cause(s) so that occurrence could be remedied. Our hypothesis was that baseplate design features such as asymmetric shape when aligned in KA would consistently contribute to posterior rim loading in the lateral compartment.MethodsBased on analysis of fluoroscopic images of 50 patients performing dynamic, weight bearing deep knee bend and step up and of postoperative CT images, five possible causes were investigated. Causes included internal rotation of the baseplate when positioned in KA; posterior position of the lateral femoral condyle at extension; internal tibial rotation with flexion; internal rotational deviation of the baseplate from the KA rotation target; and posterior slope.ResultsThe incidence of posterior rim loading was 18% (9 of 50 patients). When positioned in KA, the asymmetric baseplate left 15% versus 10% of the AP depth of the lateral compartment uncovered posteriorly for posterior rim loading and non-posterior rim loading groups, respectively (p = 0.009). The lateral femoral condyle at extension was more posterior by 4 mm for the posterior rim loading group (p = 0.003).ConclusionsPosterior rim loading in the lateral compartment was caused in part by the asymmetric design of the tibial baseplate designed for mechanical alignment which was internally rotated when positioned in KA thus under-covering a substantial percentage of the posterior lateral tibia. This highlights the need for new, asymmetric baseplates designed to maximize coverage when used in KA.Level of evidenceIII.

Aims: Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies. Methods: In 137 robotic-assisted TKAs, extension and flexion stressed gap laxities and bone resections were measured. The primary outcome was the proportion and magnitude of medial and lateral SPI (gap differential > 2.0 mm) for KA, MA, and FA. Secondary outcomes were the proportion of knees with severe (> 4.0 mm) SPI, and resection thicknesses for each technique, with KA as reference. Results: FA showed significantly lower rates of medial and lateral SPI (2.9% and 2.2%) compared to KA (45.3%; p < 0.001, and 25.5%; p < 0.001) and compared to MA (52.6%; p < 0.001 and 29.9%; p < 0.001). There was no difference in medial and lateral SPI between KA and MA (p = 0.228 and p = 0.417, respectively). FA showed significantly lower rates of severe medial and lateral SPI (0 and 0%) compared to KA (8.0%; p < 0.001 and 7.3%; p = 0.001) and compared to MA (10.2%; p < 0.001 and 4.4%; p = 0.013). There was no difference in severe medial and lateral SPI between KA and MA (p = 0.527 and p = 0.307, respectively). MA resulted in thinner resections than KA in medial extension (mean difference (MD) 1.4 mm, SD 1.9; p < 0.001), medial flexion (MD 1.5 mm, SD 1.8; p < 0.001), and lateral extension (MD 1.1 mm, SD 1.9; p < 0.001). FA resulted in thinner resections than KA in medial extension (MD 1.6 mm, SD 1.4; p < 0.001) and lateral extension (MD 2.0 mm, SD 1.6; p < 0.001), but in thicker medial flexion resections (MD 0.8 mm, SD 1.4; p < 0.001). Conclusion: Mechanical and kinematic alignment (measured resection techniques) result in high rates of SPI. Pre-resection angular and translational adjustments with functional alignment, with typically smaller distal than posterior femoral resection, address this issue. Cite this article: Bone Jt Open 2024;5(8):681–687.

Purpose: The coronal plane alignment of the knee (CPAK) classification has been introduced as a simple system to classify knee phenotypes based on leg alignment [hip–knee–ankle angle (HKA) and joint line obliquity (JLO)]. Differences in post-operative phenotype between mechanical alignment (MA) and kinematic alignment (KA) total knee arthroplasty (TKA) have been reported, but not the phenotypes after unicompartmental knee arthroplasty (UKA). Moreover, most studies have focused upon Western populations. This study compared pre- and post-operative knee phenotypes between MA-TKA, KA-TKA, and UKA in a Japanese cohort. Methods: In this study, 230 knees in 165 patients who underwent UKA, 124 knees in 80 patients who underwent MA-TKA, and 80 knees in 51 patients who underwent restricted KA-TKA in Takatsuki General Hospital between March 2019 and January 2021 were retrospectively investigated. Pre- and post-operative lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were measured, and JLO (MPTA ​+ ​LDFA) and arithmetic HKA (aHKA) (MPTA – LDFA) were calculated and compared between the surgeries. Results: Pre-operative JLO and aHKA did not significantly differ between the three groups (pre. JLO, p ​= ​0.164; pre. aHKA, p ​= ​0.13). Pre-operatively, 62.0% of knees were categorized as type I (varus leg alignment and medially sloped joint line). After UKA, 59.1% of type I inherited the pre-operative phenotype, whereas most cases were altered in MA-TKA and KA-TKA (4.8% and 30.0%, respectively, inherited the pre-operative phenotype). Conclusions: The pre-operative phenotype was mostly inherited after UKA and to a lesser extent after KA-TKA, whereas it tended to be altered after MA-TKA.

Ideal target limb alignment remains a debated topic in total knee arthroplasty (TKA). We aimed to determine the effect of limb alignment correction on patient-reported outcomes and knee range of motion (ROM) following TKA. In this retrospective analysis, patients (N = 409) undergoing primary TKA at a single institution were studied. Using full leg-length radiographs, limb alignment was measured preoperatively and postoperatively. Patients were categorized by preoperative (Preop) alignment (varus > 0°; valgus < 0°). Preop varus patients were then divided as follows based on postoperative alignment: neutral (VAR-NEUT, 0 ° ± 2), remaining in varus (VAR-rVAR, ≥ 3 °), and cross-over to valgus (VAR-CO, ≤ −3 °). Similarly, Preop valgus patients were divided as follows for postoperative alignment: neutral (VAL-NEUT, 0 ° ± 2), remaining in valgus (VAL-rVAL, ≤ −3 °), and cross-over to varus (VAL-CO, ≥ 3 °). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement survey scores were collected at preoperatively as well as at 6 weeks, 3, 6, and 12 months postoperatively. Knee ROM was collected at 2 weeks, 6 to 12 weeks, and >6 months postoperatively. An analysis of variance repeated on time followed by a Bonferroni post hoc test was used to compare outcomes for the postoperative alignment subgroups. Preop Varus patients : Those in the VAR-CO group (overcorrected to −4.03° ± 1.95valgus) were observed to have lower Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores at 3, 6, and 12 months postoperatively compared to those in the NEUT group (P <.05). This finding was paired with reduced ROM at 6 to 12 weeks postoperatively in the VAR-CO group compared to VAR-NEUT and VAR-rVAR (P <.05). Preop Valgus patients: Those in the VAL-rVal group (left in −4.39° ± 1.39valgus) were observed to have reduced knee flexion at 6 to 12 weeks postoperatively compared to VAL-NEUT and VAL-CO. These findings indicate that postoperative valgus alignment via either crossing over to valgus (VAR-CO) or remaining in valgus (VAL-rVAL) alignment may result in less preferable outcomes than correction to neutral or slightly varus alignment. [ABSTRACT FROM AUTHOR]

Individualized alignment techniques have gained major interest in an effort to increase satisfaction among total knee arthroplasty patients. This study aimed to compare postoperative alignment between kinematic alignment (KA) and mechanical alignment (MA) and assess whether KA significantly deviates from the principle of aligning the limb as close to neutral alignment as possible. There were 234 patients who underwent robotic-assisted total knee arthroplasty using an unrestricted KA and a strict MA technique (KA: 145, MA: 89). The lateral distal femoral angle, medial proximal tibia angle, and the resultant arithmetic hip-knee-ankle angle (aHKA) were measured. The aHKA < 0 indicated varus alignment, while the aHKA > 0 indicated valgus knee alignment. The primary outcome was the frequency of cases that resulted in an aHKA of ± 4° of neutral (0°), as assessed on full-leg standing radiographs obtained at 6 weeks postoperatively. The secondary outcome was the change in coronal plane alignment of the knee classification type from preoperative to postoperative between the MA and KA groups. The mean preoperative aHKA was similar between the 2 groups (P =.19). The KA group had a mean postoperative aHKA of −1.4 ± 2.4°, while the MA group had a mean postoperative aHKA of −0.5 ± 2.1°. No significant difference in limb alignment was identified between KA and MA cases that resulted in hip-knee-ankle angle of ± 4° being neutral (91.7 versus 96.6%, P =.14). There were 97.2% of cases in the KA group that fell within the ± 5° range. The MA group was associated with a significantly higher rate of coronal plane alignment of the knee classification type change from preoperatively to postoperatively (P <.001). Kinematic alignment achieved similar postoperative aHKA compared to MA, and thus did not significantly deviate from the principle of aligning the limb as close to neutral alignment as possible. Surgeons should feel comfortable starting to introduce individualized alignment techniques. Without being restricted by boundaries, postoperative alignment will be within 5 degrees of neutral 97% of the time. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this systematic review was to compare patient satisfaction patient‐reported outcomes (PROMs) levels after mechanically aligned (MA) and kinematically aligned (KA) total knee arthroplasty (TKA). Methods: A systematic literature search following PRISMA guidelines was conducted on PubMed, Embase, Medline and Scopus to identify potentially relevant articles for this review, published from the beginning of March 2013 until the end of October 2023. Only articles reporting satisfaction after KA TKA, MA TKA or both were included, which use valid and reliable tools for the evaluation and reporting of satisfaction after TKA. Title, authors, year of publication, study design, level of evidence, follow‐up period, patients' demographic data, sample size, type of satisfaction score, postoperative satisfaction score, postoperative alignment, statistical significance, as well as other variables, were extracted for analysis. An Agency for Healthcare Research and Quality's (AHRQ) design‐specific scale was used for assessing randomized control trials (RCTs). The nonrandomized control trials were evaluated by using the Joanna Briggs Institute's (JBI) Critical Appraisal Tool. The Newcastle‐Ottawa Scale (NOS) was also used to assess cohort studies, while case series were evaluated using the NIH Quality Assessment Tool for Case Series Studies. Results: The initial search identified 316 studies, of which 178 were considered for screening. Eleven studies completely fulfilled the inclusion criteria, including one RCT, five nonrandomized control trials/quasi‐experiments, three case series, and two cohort studies. The total number of patients recruited for MA TKA was 1740. Conversely, 497 patients were enrolled for KA TKA. Five studies used the visual analogue scale (VAS) for assessing postoperative patient satisfaction, four used the Knee Society Score (KSS) 2011 version and two Likert‐based types of scores. Overall, the highest mean satisfaction score of KSS 2011 was 31.5 ± 6.6 in the MA group, and 29.8 ± 80 in the KA group in four studies. All of them showed high postoperative patient satisfaction rates for both MA and KA TKA, but with no statistically significant difference between them (p > 0.05). Conclusion: Both mechanically aligned total knee arthroplasty, as well as kinematically aligned total knee arthroplasty led to high rates of postoperative patient satisfaction, with no statistically significant differences between them. Level of Evidence: Level III, systematic review. [ABSTRACT FROM AUTHOR]

Purpose: For primary total knee arthroplasty (TKA), there is an increasing trend towards patient‐specific alignment strategies such as kinematic alignment (KA) and inverse kinematic alignment (iKA), which by restoring native joint mechanics may yield higher patient satisfaction rates. Second, the most recent Australian joint registry report describes favourable revision rates for conventionally instrumented TKA compared to technology‐assisted techniques such as those using navigation, robotics or custom‐cutting blocks. The aim of this technique article is to describe in detail a surgical technique for TKA that: (1) utilises the principles of iKA and (2) uses conventionally instrumented guided resections thereby avoiding the use of navigation, robotics or custom blocks. Methods: A TKA technique is described, whereby inverse kinematic principles are utilised and patient‐specific alignment is achieved. Additionally, the patellofemoral compartment of the knee is restored to the native patellofemoral joint line. The sequenced technical note provided may be utilised for cemented or cementless components; cruciate retaining or sacrificing designs and for fixed or rotating platforms. Results: An uncomplicated, robust and reproducible technique for TKA is described. Discussion: Knee arthroplasty surgeons may wish to harness the emerging benefits of both a conventionally instrumented technique and a patient‐specific alignment strategy. Level of Evidence: Level V. [ABSTRACT FROM AUTHOR]

Background: There is no consensus on whether mechanical alignment (MA) or kinematic alignment (KA) should be chosen for total knee arthroplasty (TKA) for coronal plane alignment of the knee (CPAK) Type I with a varus arithmetic HKA (aHKA) and apex distal joint line obliquity (JLO). The aim of this study was to investigate whether MA or KA is preferable for soft tissue balancing in TKA for this phenotype. Method: This prospective cohort study included 64 knees with CPAK Type I osteoarthritis that had undergone cruciate-retaining TKA. Using optical tracking software, we simulated implant placement in the Mako system before making the actual bone cut and compared the results between MA and KA. Extension balance (the difference between medial and lateral gaps in extension) and medial balance (the difference in medial gaps in flexion and extension) were examined. These gap differences within 2 mm were defined as good balance. Achievement of overall balance was defined as an attainment of good extension and medial balance. The incidence of balance in each patient was compared with an independent sample ratio test. Results: Compared with the MA group, the KA group achieved better soft tissue balance in extension balance (p < 0.001). A total of 75% of the patients in the KA group achieved overall balance, which was greater than the 38% achieved in the MA group (p < 0.001). Conclusions: In robot-assisted TKA for CPAK Type I osteoarthritis, KA achieved knee balance during extension without soft tissue release in a greater percentage of patients than MA. [ABSTRACT FROM AUTHOR]

Purpose: Accurate assessment of the knee joint line is essential for surgeries involving the knee. The knee joint line obliquity (KJLO) is a radiological measurement that evaluates the position of the knee joint relative to the ground and is frequently used in preoperative planning and clinical follow‐up. On the other hand, coronal plane alignment of the knee (CPAK) classifications assesses the joint line as the summation of the medial proximal tibial angle (MPTA) and mechanical lateral distal femoral angle (mLDFA). The purpose of this study is to determine the concordance of these two measurement techniques. Methods: This cross‐sectional study evaluated the long‐leg standing radiographs (LSRs) of 164 healthy knees. The extremity KJLO and CPAK classification JLO were measured twice by two observers at 8‐week intervals. The knee joint line apex positions (proximal, neutral and distal) of the two measurement techniques are compared (concordance or discordant). The intraobserver and interobserver reliability were examined using the intraclass correlation coefficient (ICC). Possible causes of the discordant were evaluated with univariate and multivariate logistic regression analysis. Results: CPAK classification detected the KJLO apex position in 70 extremities (42.7%) only. Subgroups CPAK JLO detected 13.6% of the proximal apex, 20.4% of the neutral, and 90.7% of the distal apex (p < 0.01). Upon multivariate logistic regression analysis, the variable KJLO apex position (proximal, neutral vs. distal, odds ratio (OR) = 10.291, 95% confidence interval [CI] = 2.225–25.656, and (p < 0.01) was determined as a risk factor for discordant. Conclusion: The CPAK JLO measurement technique can be misleading in defining the KJLO apex position and the concordance between them is less than 50%. It has a high tendency to misleadingly predict proximal and neutral apex positions, which can potentially have negative implications for assessing the joint line. Level of Evidence: Level I. [ABSTRACT FROM AUTHOR]

Purpose: While the coronal plane alignment of the knee (CPAK) classification serves as a useful guide in personalising total knee arthroplasty (TKA), the extent of its correlation with segmental coronal extra‐articular knee deformities remains uncertain. This study aims to investigate the potential correlation between CPAK matrix groups and segmental coronal extra‐articular deformities in prearthritic knees, shedding light on the relationship between these two factors that seems to be both essential to perform personalised TKA. Materials and Methods: A radiological assessment of 1240 nonarthritic knees was performed by evaluating lower limb measurements following the protocol established by Paley et al. Subsequently, all knees were classified into their respective CPAK matrix groups. In our quest to discern any correlation between the CPAK matrix groups and the presence of segmental coronal extra‐articular knee deformities, nine potential coronal extra‐articular deformity phenotype (CEDP) groupswere identified based on medial proximal tibial angle (MPTA) and mechanical lateral distal femoral angle (mLDFA). Neutral values for MPTA and mLDFA were set at 90.0° ± 3.0° and then at 87.0° ± 2.0°. Each CPAK matrix group underwent detailed coronal morphology analysis and then, segmental coronal extra‐articular deformities were assessed by comparing them with the CEDP groups. Results: The study revealed a mean hip–knee–ankle angle (HKA) of 178.6° ± 4.4°, mLDFA of 86.9° ± 2.5°, MPTA of 85.4° ± 2.4°, arithmetic HKA of −1.4° ± 3.2° and joint line obliquity of 172.5° ± 3.7°. The varus CPAK groups (I/IV/VII) included 435 patients, the neutral groups (II/V/VIII) comprised 630 patients and the valgus groups (III/VI/IX) had 175 patients. Notably, CPAK matrix groups were not distinctly associated with specific coronal extra‐articular deformity phenotype (CEDP) groups. Particularly among the most common CPAK matrix groups (I/II/III/IV/V), there was a significant variation in segmental coronal extra‐articular deformity patterns. Moreover, when neutral MPTA/mLDFA values were set at 87.0° ± 2.0°, the CPAK matrix groups exhibited even greater variability in coronal extra‐articular deformities. Conclusion: The CPAK matrix groups do not exhibit a direct correlation with a specific extra‐articular deformity pattern (CEDP), thus rendering them unsuitable for determining segmental coronal extra‐articular knee deformities. Level of Evidence: Level III, retrospective diagnostic study. [ABSTRACT FROM AUTHOR]

Abstract Background Mechanical alignment with total knee arthroplasty (TKA) has been widely used since the implantation of the first prosthetic knee. Multiple studies have reported 80% patient satisfaction with TKA. However, the reported patients’ dissatisfaction is believed to be caused by having to convert different knee alignments to neutral alignments. It is postulated that a change in the CPAK classification of knees leads to patient dissatisfaction. Thus, we hypothesized that a change in CPAK classification with robot-assisted TKA with mechanical alignment does not significantly lead to patient dissatisfaction. Methods We retrospectively analyzed 134 patients who underwent robot-assisted mechanical alignment total knee arthroplasty (MA-TKA) using cementless implants and classified them into CPAK system pre- and post-operatively. One year after TKA surgery, we recorded binary responses to patients’ satisfaction with the outcome of surgery and analyzed if a change in CPAK classification is associated with the outcome of surgery. Results We found that 125 out of 134 patients (93.28%) were happy with the outcome of surgery. CPAK classification was changed in 116 patients (86.57%) and maintained in 18 patients (13.43%). Our results also showed that 111 (95.7%) out of 116 patients who had a change in CPAK and 14 (77.8%) out of 18 patients who maintained their CPAK post-surgery were happy with the outcome of surgery (OR = 6.3, CI 1.741–25.17, P value = 0.019). Conclusion We concluded that changing the patient’s native joint line and CPAK classification does not significantly change the outcome of surgery in terms of satisfaction. The dissatisfaction rate of 20% as published by previous researchers may be confounded by other reasons and not just due to changes in alignment and joint line.

Purpose: Restricted kinematic alignment (rKA) in total knee arthroplasty (TKA) and medial pivot (MP) knee designs already showed superior outcomes in independent comparative studies. The objective of this study was to assess whether rKA with MP TKA provides better clinical and functional outcomes compared to mechanical alignment (MA) with MP TKA. Methods: This is a randomised, parallel two group study involving a total of 98 patients with end‐stage knee osteoarthritis. Patients were randomly allocated to either rKA or MA TKA procedures conducted with a MP prothesis using patient‐specific instruments between 2017 and 2020. Final follow‐up was at 2 years postoperatively. Demographic data and clinical and functional scores (Oxford knee score, knee society score [KSS], Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], forgotten joint score [FJS]) were collected and compared preoperative, 1 year postoperative and 2 years postoperative. Coronal plane alignment of the knee and functional knee phenotype classification were recorded. Results: A total of 47 patients (rKA) and 51 patients (MA) were included in final analysis. Superior joint awareness scores (FJS) were found at 1 year postoperative for rKA (62.2 vs. 52.4, p = 0.04). KSS subscores (expectation score, satisfaction score) improved with rKA with significant differences at both 1 and 2 years postoperatively. Major differences between rKA and MA were found in subgroup analysis of varus and neutral CPAK phenotypes. Both 1 year and 2 years postoperatively, FJS was significantly better in KA compared with MA in varus CPAK phenotypes (63.1 vs. 44.9, p = 0.03; 71.1 vs. 46.0, p = 0.005). Further clinical and functional scores showed improvement in the varus CPAK phenotypes with predominantly significant improvement in the expectation and satisfaction KSS subscores. No significant differences were found in the comparison of rKA and MA in neutral CPAK phenotypes. Conclusion: The rKA of MP TKA design shows superior patient satisfaction and self‐reported function when compared to MA MP TKA. Furthermore, rKA MP TKA shows superior joint awareness at early postoperative stage. The most important clinical relevance of this study is the clear superiority of rKA in varus phenotypes. Level of Evidence: Level II. [ABSTRACT FROM AUTHOR]

Purpose: To compare and determine the reliability and conclusiveness of the medium‐ and long‐term efficacy in terms of patient‐reported outcome measures and the risk of revisions or reoperations (RRRs) of kinematic alignment (KA) and mechanical alignment (MA) in total knee arthroplasty. Methods: A comprehensive search was conducted in Medline, EMBASE, Web of Science and Cochrane Database Library to identify relevant literature. Only randomised clinical trials (RCTs) published before July 2023 were included. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Forgotten Joint Score (FJS) and RRR were compared. Additionally, OKS and RRR were subjected to a trial sequential analysis. Results: Seven RCTs involving 572 knees were identified. The pooled analysis of the included studies demonstrated that KA showed better medium‐term WOMAC and OKS (mean difference [MD] = −6.3, 95% confidence interval [CI]: −9.52 to −2.99, p < 0.05 and MD = 1.1, 95% CI: 0.05–2.15, p < 0.05), respectively), but no significant differences were observed in the long‐term follow‐up (MD = 2.1, 95% CI: −3.21 to 7.31, not significant [n.s.] and MD = 0.01, 95% CI: −2.43 to 2.46, n.s., respectively). FJS (standardised MD = −0.03, 95% CI: −0.25 to 0.19, n.s.) and RRR (risk ratio = 1.0, 95% CI: 0.57 to 1.74, n.s.) showed no significant intergroup differences (n.s.). The evidence quality ranged from moderate to high, and the trial sequential analysis indicated the need for additional high‐quality RCTs to draw more conclusive results. Conclusions: KA showed better medium‐term WOMAC and OKS, while KA and MA had similar FJS without increasing the RRR in medium‐ and long‐term follow‐up. Further research is needed for more conclusive results. Level of Evidence: Level II (meta‐analyses). [ABSTRACT FROM AUTHOR]

Background: Mechanical alignment with total knee arthroplasty (TKA) has been widely used since the implantation of the first prosthetic knee. Multiple studies have reported 80% patient satisfaction with TKA. However, the reported patients' dissatisfaction is believed to be caused by having to convert different knee alignments to neutral alignments. It is postulated that a change in the CPAK classification of knees leads to patient dissatisfaction. Thus, we hypothesized that a change in CPAK classification with robot-assisted TKA with mechanical alignment does not significantly lead to patient dissatisfaction. Methods: We retrospectively analyzed 134 patients who underwent robot-assisted mechanical alignment total knee arthroplasty (MA-TKA) using cementless implants and classified them into CPAK system pre- and post-operatively. One year after TKA surgery, we recorded binary responses to patients' satisfaction with the outcome of surgery and analyzed if a change in CPAK classification is associated with the outcome of surgery. Results: We found that 125 out of 134 patients (93.28%) were happy with the outcome of surgery. CPAK classification was changed in 116 patients (86.57%) and maintained in 18 patients (13.43%). Our results also showed that 111 (95.7%) out of 116 patients who had a change in CPAK and 14 (77.8%) out of 18 patients who maintained their CPAK post-surgery were happy with the outcome of surgery (OR = 6.3, CI 1.741–25.17, P value = 0.019). Conclusion: We concluded that changing the patient's native joint line and CPAK classification does not significantly change the outcome of surgery in terms of satisfaction. The dissatisfaction rate of 20% as published by previous researchers may be confounded by other reasons and not just due to changes in alignment and joint line. [ABSTRACT FROM AUTHOR]

Purpose: Robotic arm‐assisted total knee arthroplasty (RTKA) enables adjustment of implant position to achieve the surgeon's preferred alignment. However, the alignment concept that most effectively enhances patient satisfaction remains unclear. This study compares the clinical outcomes of patients who underwent functionally aligned RTKA (FA‐RTKA), mechanically aligned conventional TKA (MA‐CTKA) and mechanically aligned RTKA (MA‐RTKA). Methods: A prospectively collected database was retrospectively reviewed for patients who underwent primary TKA for knee osteoarthritis. One hundred and forty‐seven knees were performed with MA‐CTKA, followed by 72 consecutive knees performed with MA‐RTKA, and subsequently, 70 consecutive knees performed with FA‐RTKA were enrolled. After 1:1 propensity score matching of patient demographics, 70 knees were finally included in each group. The extent of additional soft tissue release during surgery was identified, and the Coronal Plane Alignment of the Knee classification was utilised to categorise the alignment. At the 1‐year follow‐up, patient‐reported outcomes, including the pain Visual Analogue Scale, Knee Society Score, Western Ontario and McMaster Universities Arthritis Index and Forgotten Joint Score‐12, were also compared among the groups. Results: The FA‐RTKA group showed significantly less additional soft tissue release than the MA‐CTKA and MA‐RTKA groups (15.7%, 38.6% and 35.7%, respectively; p = 0.006). Statistically significant differences in functional scores were observed in the postoperative 1‐year clinical outcomes in favour of the FA‐RTKA group, which had a significantly larger percentage of knees that maintained constitutional alignment and joint line obliquity than those of the other groups. Conclusions: Functionally aligned TKA showed superior 1‐year postoperative patient‐reported outcomes compared with those of conventional and robotic arm‐assisted mechanically aligned TKA. Therefore, the advantage of RTKA is maximised when the implant positioning is based on functional alignment. The application of RTKA with mechanical alignment has been proven ineffective in improving the clinical outcomes of patients. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between constitutional coronal alignment and implant positioning on trochlear groove restoration in total knee arthroplasty (TKA) is poorly understood. This study aimed to determine whether the choice of alignment philosophy significantly affects the restoration of the trochlea groove. Methods: Sixty‐one imageless robotic TKAs performed by a single orthopaedic surgeon were retrospectively reviewed. In each case, the entire native trochlea was digitized to generate the native femoral anatomy, and implants were planned according to a functional alignment (FA) technique. Final implant position was recorded using the validated bone resection planes from the navigation system. Simulated femoral component positions were generated according to previously described alignment techniques: mechanical alignment (MA), gap balancing (GB), kinematic alignment (KA), restricted kinematic alignment (rKA) and restricted inverse kinematic alignment (riKA). Trochlear angle (TA), trochlear under/overstuffing and mediolateral sulcus offset were compared between the six simulated alignment techniques, as well as the final implanted technique. Further analyses investigated the effect of preoperative coronal alignment on trochlear position. Comparisons were assessed with an analysis of variance and Welch's t‐tests or Wilcoxon's rank‐sum tests with Bonferroni corrections. Results: The implanted and simulated techniques all resulted in greater TA valgus compared to the native groove (p < 0.001). The implanted technique, KA and rKA were closer to the native TA than GB, MA and riKA (p > 0.001). All alignment philosophies understuffed the native trochlea groove. KA and rKA understuffed less than all other techniques (p < 0.001), and GB understuffed more than all other techniques (p < 0.001). In extension, all techniques shifted the trochlear sulcus laterally, while in flexion, they medialized it. These effects were most prominent in GB and MA. Conclusion: Personalized alignment techniques such as KA and rKA, which consider variations in individual anatomy, best restore the native patellar groove compared to systematic alignment techniques when using a standardized femoral component. Level of Evidence: Level III, retrospective review. [ABSTRACT FROM AUTHOR]

Purpose: The value of computer navigation in total knee arthroplasty (TKA) for arthritic knees continues to be debated. The purpose of this study was to evaluate the value of navigated TKA associated with updated alignment philosophy. Methods: This prospective randomized controlled trial enrolled 38 consecutive patients (76 knees) and were randomly assigned to both groups. The demographic data and perioperative data were recorded. The coronal plane alignment of the knee (CPAK) classification was used to classify knee alignment phenotypes. Radiographic outcomes were measured and subgroup analysis was further performed. Clinical outcomes were evaluated using patient-reported outcome measures (PROMs). Surgery-related complications were recorded. Results: The distribution of CPAK phenotypes following constitutional aligned TKA was equivalent to the native cohort, whereas the mechanical aligned TKA dramatically altered the phenotype distribution from type I and type II to type V and type IV. Final implant positioning was different between groups, with constitutional aligned TKA having larger cTCA (P =.004), joint line obliquity (P =.006), joint line distance (P =.033) and smaller sFCA (P =.013). Subgroup analysis showed higher actual accuracy of component positioning was achieved in navigated TKA, especially in knees with deformity of > 10° (P <.05). Patients reported higher HSS score at three months postoperatively in constitutional aligned group (P =.002). One patient in navigated group suffered femoral pin site fracture caused by a minor trauma. Conclusion: Computer navigated TKA allows for restoration of constitutional alignment and minimizes soft tissue release, which when compared to mechanical alignment may be associated with superior early outcomes. [ABSTRACT FROM AUTHOR]

There is a debate about the best alignment strategies in total knee arthroplasty (TKA). Mechanical alignment (MA) targets in combination with necessary soft tissue releases are the gold standard for TKA in end-stage valgus osteoarthritis. Some authors propagate kinematic alignment (KA) with the aim of restoring the patient's native alignment and minimizing the need for soft tissue releases. Our previous studies showed that MA with standardized soft tissue release produces reproducible results, and that the preoperative phenotype does not influence the results of patients with valgus osteoarthritis. These data suggest that there is no functional advantage to preserving valgus alignment in patients with valgus osteoarthritis. Many patients with valgus osteoarthritis present with a compromised medial collateral ligament and leaving the knee in valgus could increase the risk of secondary instability. The current literature supports MA TKA with soft tissue release as the gold standard. While using more sophisticated enabling technologies like robotic surgery might allow for aiming for very slight (1–2°) valgus alignment on the femoral side, any valgus alignment outside this range should be avoided. This review paper summarizes our current knowledge on the surgical techniques of TKA in patients with valgus osteoarthritis. [ABSTRACT FROM AUTHOR]

Abstract Purpose For primary total knee arthroplasty (TKA), there is an increasing trend towards patient‐specific alignment strategies such as kinematic alignment (KA) and inverse kinematic alignment (iKA), which by restoring native joint mechanics may yield higher patient satisfaction rates. Second, the most recent Australian joint registry report describes favourable revision rates for conventionally instrumented TKA compared to technology‐assisted techniques such as those using navigation, robotics or custom‐cutting blocks. The aim of this technique article is to describe in detail a surgical technique for TKA that: (1) utilises the principles of iKA and (2) uses conventionally instrumented guided resections thereby avoiding the use of navigation, robotics or custom blocks. Methods A TKA technique is described, whereby inverse kinematic principles are utilised and patient‐specific alignment is achieved. Additionally, the patellofemoral compartment of the knee is restored to the native patellofemoral joint line. The sequenced technical note provided may be utilised for cemented or cementless components; cruciate retaining or sacrificing designs and for fixed or rotating platforms. Results An uncomplicated, robust and reproducible technique for TKA is described. Discussion Knee arthroplasty surgeons may wish to harness the emerging benefits of both a conventionally instrumented technique and a patient‐specific alignment strategy. Level of Evidence Level V.

Abstract Purpose The purpose of this systematic review was to compare patient satisfaction patient‐reported outcomes (PROMs) levels after mechanically aligned (MA) and kinematically aligned (KA) total knee arthroplasty (TKA). Methods A systematic literature search following PRISMA guidelines was conducted on PubMed, Embase, Medline and Scopus to identify potentially relevant articles for this review, published from the beginning of March 2013 until the end of October 2023. Only articles reporting satisfaction after KA TKA, MA TKA or both were included, which use valid and reliable tools for the evaluation and reporting of satisfaction after TKA. Title, authors, year of publication, study design, level of evidence, follow‐up period, patients' demographic data, sample size, type of satisfaction score, postoperative satisfaction score, postoperative alignment, statistical significance, as well as other variables, were extracted for analysis. An Agency for Healthcare Research and Quality's (AHRQ) design‐specific scale was used for assessing randomized control trials (RCTs). The nonrandomized control trials were evaluated by using the Joanna Briggs Institute's (JBI) Critical Appraisal Tool. The Newcastle‐Ottawa Scale (NOS) was also used to assess cohort studies, while case series were evaluated using the NIH Quality Assessment Tool for Case Series Studies. Results The initial search identified 316 studies, of which 178 were considered for screening. Eleven studies completely fulfilled the inclusion criteria, including one RCT, five nonrandomized control trials/quasi‐experiments, three case series, and two cohort studies. The total number of patients recruited for MA TKA was 1740. Conversely, 497 patients were enrolled for KA TKA. Five studies used the visual analogue scale (VAS) for assessing postoperative patient satisfaction, four used the Knee Society Score (KSS) 2011 version and two Likert‐based types of scores. Overall, the highest mean satisfaction score of KSS 2011 was 31.5 ± 6.6 in the MA group, and 29.8 ± 80 in the KA group in four studies. All of them showed high postoperative patient satisfaction rates for both MA and KA TKA, but with no statistically significant difference between them (p > 0.05). Conclusion Both mechanically aligned total knee arthroplasty, as well as kinematically aligned total knee arthroplasty led to high rates of postoperative patient satisfaction, with no statistically significant differences between them. Level of Evidence Level III, systematic review.

Aims: While mechanical alignment (MA) is the traditional technique in total knee arthroplasty (TKA), its potential for altering constitutional alignment remains poorly understood. This study aimed to quantify unintentional changes to constitutional coronal alignment and joint line obliquity (JLO) resulting from MA. Methods: A retrospective cohort study was undertaken of 700 primary MA TKAs (643 patients) performed between 2014 and 2017. Lateral distal femoral and medial proximal tibial angles were measured pre- and postoperatively to calculate the arithmetic hip-knee-ankle angle (aHKA), JLO, and Coronal Plane Alignment of the Knee (CPAK) phenotypes. The primary outcome was the magnitude and direction of aHKA, JLO, and CPAK alterations. Results: The mean aHKA and JLO increased by 0.1° (SD 3.4°) and 5.8° (SD 3.5°), respectively, from pre- to postoperatively. The most common phenotypes shifted from 76.3% CPAK Types I, II, or III (apex distal JLO) preoperatively to 85.0% IV, V, or VI (apex horizontal JLO) postoperatively. The proportion of knees with apex proximal JLO increased from 0.7% preoperatively to 11.1% postoperatively. Among all MA TKAs, 60.0% (420 knees) were changed from their constitutional alignments into CPAK Type V, while 40.0% (280 knees) either remained in constitutional Type V (5.0%, 35 knees) or were unintentionally aligned into other CPAK types (35.0%; 245 knees). Conclusion: Fixed MA targets in TKA lead to substantial changes from constitutional alignment, primarily a significant increase in JLO. These findings enhance our understanding of alignment alterations resulting from both unintended changes to knee phenotypes and surgical resection imprecision. Cite this article: Bone Jt Open 2024;5(2):109–116.

Purpose: Total knee arthroplasty (TKA) reduces knee pain to improve knee function for painful knee osteoarthritis and provides excellent long-term survivorship. However, approximately 20% of patients remain dissatisfied. To improve patient satisfaction, several modifications of knee alignment have recently been introduced. The aim of this paper is to review various alignment techniques. Methods: Principles, surgical techniques, and clinical results of various alignment techniques for TKA were searched in the PubMed database. Results: Mechanical alignment aims to cut perpendicular to the mechanical axes of the femur and tibia in the coronal plane. The threshold of the deviation from the mechanical axis for long-term survivorship is still unknown. Anatomical alignment aims at neutral alignment but 2–3 varus joint line relative to the mechanical axis. Although catastrophic polyethylene wear was reported in the 1990s, excellent mid-term clinical results were recently reported using surgical robots. Kinematic alignment aims to restore the pre-arthritic native limb alignment and avoid soft tissue release. To avoid excessive alignment deviation, some modification such as inverse kinematic, restricted kinematic, and modified kinematic alignments are also introduced. Equal or better clinical scores have been reported in short term. Functional alignment TKA aims to restore pre-arthritic alignment and achieve balanced soft tissue tension by adjusting bone resections using robotic-assisted technology. Conclusion: Wide range of clinical results exist for new alignment techniques in the short term. The safe range of alignment for long-term survivorship remains unknown. Further high-quality studies should be performed to warrant the widespread use of new alignment techniques.

Abstract Objective A thorough examination of the available approaches is crucial to comprehensively understand the variance among the alignment strategies employed in total knee arthroplasty (TKA). In this study, we assessed the functional outcomes during the perioperative and postoperative periods of TKA in patients using generic instruments with varus knee to compare the mechanical alignment (MA) and kinematic alignment (KA) procedures. Methods A total of 127 patients from the First Affiliated Hospital of Wannan Medical College who had undergone unilateral TKA between November 2019 and April 2021 were included. The patients with varus knee deformity were categorized into two groups [type I (n = 64) and type IV (n = 63)] based on the modified coronal plane alignment of the knee (mCPAK) classification. The type I and IV groups were further subdivided into MA (n = 30 and n = 32) and KA subgroups (n = 34 and n = 21), respectively. The clinical information collected included sex, surgical side, age, body mass index, and perioperative data [including operation time, intraoperative blood loss, length of hospital stay, and the American Society of Anesthesiologists (ASA) classification]. All patients were monitored for 12 months post-surgery to evaluate the recovery of knee joint function. During this period, the Knee Disability and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and the active range of motion (AROM) and visual analog scale (VAS) pain scores were compared at different time points, i.e., before the operation and 6 weeks, 6 months, and 12 months post-operation. Additionally, the patients’ subjective experiences were assessed at 6 and 12 months post-surgery using Forgotten Joint Score Knee (FJS-12 Knee), while complications were recorded throughout the monitoring period. Results No significant variances were observed in ASA classification, operation duration, blood loss volume during surgery, and hospital stay length between the patients who underwent KA TKA and those who received MA TKA (P > 0.05). During the initial 6 weeks post-operation, the KA group exhibited a significantly reduced average VAS pain score (P 0.05). Furthermore, the KA group had significantly higher scores on the KOOS JR at 6 weeks, 6 months, and 1 year following the surgery (P 0.05). The KA cohort also exhibited a significant increase in FJS-12 Knee at 1 year following the operation (P 0.05). Thus, compared to the MA method, the KA procedure provided pain relief and improved active motion range within 6 weeks after the surgery in patients undergoing TKA. Further, the KOOS JR exhibited significant increases at 6 weeks, 6 months, and 1 year while the FJS-12 Knee demonstrated a significant increase at 1 year after the KA TKA procedure. Conclusion Therefore, our study results suggest that the KA approach can be considered in patients using generic instruments with varus alignment of the knee, particularly those with mCPAK type I and IV varus knees, to help improve patient satisfaction.

Purpose: The aim of this study was to identify if constitutional alignment and preoperative radiologic parameters determined whether medial gap balancing was required in mechanically aligned total knee arthroplasty (TKA). Methods: Two hundred and sixty three patients with 394 consecutive knees who underwent primary TKAs were retrospectively analysed in this study. Selective sequential multiple needle puncturing (MNP) was performed for medial ligament balancing when required. Constitutional alignment, which was determined using the Coronal Plane Alignment of the Knee (CPAK) classification, as well as preoperative and postoperative radiologic parameters was evaluated to identify factors which predicted the need for MNP. Results: One hundred and fifty eight (40.1%) knees required medial ligament balancing with MNP. Patients who required MNP during surgery had significantly more constitutional varus, more varus preoperative mechanical Hip–Knee–Ankle angle (mHKA), smaller preoperative medial proximal tibial angle (MPTA) and a larger change in mHKA and MPTA after surgery than those who did not. Patients with constitutional varus also had a higher incidence of having had MNP to both anterior and posterior superficial medial collateral ligament (sMCL) fibres. There was no significant difference in preoperative lateral distal femoral angle (LDFA), posterior tibial slope (PTS) and varus–valgus difference (VVD) between groups. Conclusion: Ligament balancing using MNP was determined by constitutional alignment rather than medial soft tissue contracture. Patients with constitutional varus who had a larger medio-lateral gap difference in extension also had a higher incidence of having had MNP to both anterior and posterior sMCL fibres. Level of evidence: Retrospective comparative study, level IV. [ABSTRACT FROM AUTHOR]

This study aimed to compare two alignment strategies in the same patient undergoing simultaneous bilateral robotic-assisted TKA (SB-RATKA): mechanical alignment (MA), the gold-standard, and functional alignment (FA), a balance-driven, personalized alignment strategy. The outcome measures included quantitative assessment of soft-tissue release, incidence of knee balance, and post-operative pain. This was a prospective, self-controlled, randomized-controlled trial involving 72 patients who underwent SB-RATKA using the MAKO® robotic system with comparable grades of deformity and pain in both knees. 65 patients were finally included with one alignment strategy done per knee, with the patients blinded to the strategy used. The study recorded the additional soft-tissue releases required, incidence of pre-balance, and daily post-operative VAS pain scores. The mean age of the study population was 57.95 years, with a female preponderance (N = 53, 81.6%). MA group had significantly more medial compartment tightness in both flexion (MA-15.6 ± 1.8; FA-17 ± 1.3) and extension (MA-14.9 ± 1.9; FA-17 ± 1.1) (p < 0.0001) compared to the FA group after dynamic balancing. 66% of knees in the FA group (N = 43) achieved pre-balance compared to 32.3% in the MA group (N = 21) (p < 0.0001). VAS scores showed a significant reduction in pain in the FA group up to 72 h post-surgery (p < 0.0001). The requirement for posteromedial release (PM), posterior capsular (PC) release, tibial reduction osteotomy (TRO), and superficial MCL pie crusting (sMCL) were significantly lower in FA (PM-22, PC-13, TRO-8, sMCL-2) compared to MA (PM-44, PC-29, TRO-18, sMCL-8). Functional alignment strategy consistently resulted in a higher incidence of knee balance with a significant reduction in soft-tissue releases and immediate post-operative pain when compared to MA in the same patient undergoing SB-RATKA. Therapeutic Level 1. [ABSTRACT FROM AUTHOR]

Abstract Background To ensure the success of total knee arthroplasty (TKA), precise bone cuts and a well-balanced soft tissue envelope are crucial. Soft tissue release may be necessary, subject to various factors. Therefore, documenting the type, frequency, and necessity of soft tissue releases can establish a benchmark for comparing different alignment techniques and philosophies and evaluating their outcomes. The purpose of this study was to demonstrate that robotic-assisted knee surgery requires minimal soft tissue release. Methods We prospectively documented and retrospectively reviewed the soft tissue releases employed in securing ligament balance in the first 175 patients who received robotic-assisted TKAs at Nepean Hospital. ROSA was utilized in all surgeries with the aim of restoring mechanical coronal alignment, with a flexion gap balancing technique. Surgeries were performed between December 2019 to August 2021 by a single surgeon who used a standard medial parapatellar approach without a tourniquet, and the cementless persona prosthesis. All patients were followed up for a minimum of 6 months post-surgery. Soft tissue releases included any form of medial release for varus knee, posterolateral release for valgus knee and PCL fenestration or sacrifice. Results There were 131 female and 44 male patients, aged between 48 to 89 years (average 60 years). The preoperative HKA ranged from 22 degrees varus to 28 degrees valgus, with 71% of patients presenting with a varus deformity. For the whole group, the no need for soft tissue release was documented in 123 patients (70.3%), small fenestrated releases of PCL in 27 (15.4%), sacrifice of PCL in 8 (4.5%), medial releases in 4 (2.3%) and posterolateral releases in 13 (7.4%). In 29.7% of patients in whom a soft tissue release was necessary for balance, over half were/received minor fenestrations of the PCL. Outcomes to date included no revisions or impending revisions, 2 MUAs (1%), and Oxford knee scores averaged 40 at 6 months. Conclusion We concluded that Robot technology enhanced the precision of bone cuts and allowed for titration of required soft tissue releases to achieve optimal balance.

BackgroundClassical models of the knee assume the joint line is parallel to the floor and the tibial mechanical axis (TMA) is orthogonal to the floor. Our study characterizes the angle subtended by the TMA and floor during bipedal stance, called the tibial axis orientation angle (TAOA), and tests the assumption that the TMA should be orthogonal to the floor.MethodsWe reviewed the nonoperative knee on full-length, standing radiographs in patients undergoing total knee arthroplasty between 2013 and 2017. Radiographic measurements were obtained for hip-knee-ankle axis, medial proximal tibial angle (MPTA), joint line orientation angle, and TAOA and correlated by regression analysis. The cohort was stratified by hip-knee-ankle axis alignment to determine statistical differences in knee angle values. Demographic data were collected to assess associations with knee angles.ResultsOur cohort included 68 patients, with 56% female and average age of 62.3 years. Varus knees comprised 56% of the cohort, with 7% neutral and 37% valgus. The cohort demonstrated an MPTA of 3.06°, TAOA of 2.67°, and joint line orientation angle of 0.36°. Varus knees had a higher MPTA (4.26°) and TAOA (4.74°) than valgus knees (P < .001). MPTA and TAOA were correlated on regression analysis (r2 = 0.465), and all angles were statistically different between sexes.ConclusionThe angle between the TMA and floor, called TAOA, is not orthogonal in normal knees, contrary to assumptions in classical biomechanics. Knee angles vary significantly between varus and valgus cohorts, and the distinction between these cohorts should be noted when evaluating normal joint line angles.

Purpose: The purpose of this study was to investigate the in vivo kinematics of the same femoral design mechanically aligned posterior-stabilised (PS) total knee arthroplasty (TKA) with either fixed-bearing (FB) or mobile-bearing (MB) inlay, implanted by the same surgeon, using model-based dynamic radiostereometric analysis (RSA). The hypothesis of the present study was that the MB design would show wider axial rotation than the FB design, without affecting the clinical outcomes. Materials and methods: A cohort of 21 non-randomised patients (21 DePuy Attune PS-FB) was evaluated by dynamic RSA analysis at a minimum 9-month follow-up, while performing differently demanding daily living activities such as sit to stand (STS) and deep knee lunge (DKL). Kinematic data were compared with those of a cohort of 22 patients implanted with the same prosthetic design but with MB inlay. Anterior–posterior (AP) translations, varus–valgus (VV) and internal–external (IE) rotations of the femoral component with respect to the tibial baseplate were investigated. Translation of medial and lateral compartment was analysed using the low point method according to Freeman et al. Questionnaires to calculate objective and subjective clinical scores were administered preoperatively and during follow-up visit by the same investigator. Results: The FB TKA design showed lower AP translation during STS (6.8 ± 3.3 mm in FB vs 9.9 ± 3.7 mm in MB, p = 0.006*), lower VV rotation (1.9 ± 0.8° in FB vs 5.3 ± 3.3° in MB, p = 0.005) and lower IE rotation (2.8 ± 1.1° in FB vs 9.5 ± 4.3° in MB, p = 0.001) during DKL than the mobile-bearing TKA design. Posterior-stabilised FB group showed significant lower translation of the low point of the medial compartment than the MB group (p = 0.008). The percentage of patients performing medial pivot in the FB group was higher compared to MB group in the examined motor tasks. No significant differences in post-operative range of motion (117° ± 16° for FB group and 124° ± 13° for MB group) and in clinical outcomes emerged between the two cohort. Conclusions: The FB and MB designs differed in AP translations, VV rotations and IE rotations of the femoral component with respect to the tibial component in STS and DKL. Furthermore, FB cohort reported a significant higher percentage of medial pivot with respect to MB cohort. Despite this, no differences in clinical outcomes were detected between groups. Both designs showed stable kinematics and represent a viable option in primary TKA. Level of evidence: Prospective cohort study, II. [ABSTRACT FROM AUTHOR]

Purpose: Robotic-assisted total knee arthroplasty (R-TKA) has emerged as an alternative to improve the results of the conventional manual TKA (C-TKA). The aim of this study was to analyse the high-level studies comparing R-TKA and C-TKA in terms of clinical outcomes, radiological results, perioperative parameters, and complications. Methods: The literature search was conducted on three databases (PubMed, Cochrane, and Web of Science) on 1 February 2023 according to the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Inclusion criteria were: randomized controlled trials (RCTs), written in English language, published in the last 15 years, focusing on the comparison of C-TKA and R-TKA results. The quality of each article was assessed using the Cochrane risk-of-bias tool for randomized trials version 2 (RoB 2). The statistical analysis was carried out using random effects (DerSimonian & Laird) for weighted mean difference (MD) of the continuous variables and Peto method for odds ratios of the dichotomous variables. Results: Among the 2905 articles retrieved, 14 RCTs on 12 series of patients treated with mechanically aligned implants were included. A total of 2255 patients (25.1% males and 74.9% females; mean age 62.9 ± 3.0; mean BMI 28.1 ± 1.3) were analysed. The results of this systematic review and meta-analysis showed that R-TKA did not provide overall superior results compared to C-TKA in mechanically aligned implants in terms of clinical and radiological outcomes. R-TKA showed longer operative time (MD = 15.3 min, p = 0.004) and similar complication rates compared to C-TKA. A statistically significant difference in favour of R-TKA was found in the posterior-stabilized subgroup in terms of radiological outcomes (hip–knee–ankle angle MD = 1.7, p < 0.001) compared to C-TKA, although without resulting in appreciable difference of clinical outcomes. Conclusion: R-TKA did not provide overall superior results compared to C-TKA in terms of clinical and radiological outcomes, showing longer operative time and similar complication rates. Level of evidence: Level I. [ABSTRACT FROM AUTHOR]

Objective: A thorough examination of the available approaches is crucial to comprehensively understand the variance among the alignment strategies employed in total knee arthroplasty (TKA). In this study, we assessed the functional outcomes during the perioperative and postoperative periods of TKA in patients using generic instruments with varus knee to compare the mechanical alignment (MA) and kinematic alignment (KA) procedures. Methods: A total of 127 patients from the First Affiliated Hospital of Wannan Medical College who had undergone unilateral TKA between November 2019 and April 2021 were included. The patients with varus knee deformity were categorized into two groups [type I (n = 64) and type IV (n = 63)] based on the modified coronal plane alignment of the knee (mCPAK) classification. The type I and IV groups were further subdivided into MA (n = 30 and n = 32) and KA subgroups (n = 34 and n = 21), respectively. The clinical information collected included sex, surgical side, age, body mass index, and perioperative data [including operation time, intraoperative blood loss, length of hospital stay, and the American Society of Anesthesiologists (ASA) classification]. All patients were monitored for 12 months post-surgery to evaluate the recovery of knee joint function. During this period, the Knee Disability and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and the active range of motion (AROM) and visual analog scale (VAS) pain scores were compared at different time points, i.e., before the operation and 6 weeks, 6 months, and 12 months post-operation. Additionally, the patients' subjective experiences were assessed at 6 and 12 months post-surgery using Forgotten Joint Score Knee (FJS-12 Knee), while complications were recorded throughout the monitoring period. Results: No significant variances were observed in ASA classification, operation duration, blood loss volume during surgery, and hospital stay length between the patients who underwent KA TKA and those who received MA TKA (P > 0.05). During the initial 6 weeks post-operation, the KA group exhibited a significantly reduced average VAS pain score (P < 0.05), with no such differences at 6 months and 1 year after the surgery (P > 0.05). Furthermore, the KA group had significantly higher scores on the KOOS JR at 6 weeks, 6 months, and 1 year following the surgery (P < 0.05). Moreover, the AROM score of the KA group significantly improved only at 6 weeks after the surgery (P < 0.05); however, no prominent differences were found at 6 months and 1 year after the operation (P > 0.05). The KA cohort also exhibited a significant increase in FJS-12 Knee at 1 year following the operation (P < 0.05), whereas no such difference was detected at 6 months following the surgery (P > 0.05). Thus, compared to the MA method, the KA procedure provided pain relief and improved active motion range within 6 weeks after the surgery in patients undergoing TKA. Further, the KOOS JR exhibited significant increases at 6 weeks, 6 months, and 1 year while the FJS-12 Knee demonstrated a significant increase at 1 year after the KA TKA procedure. Conclusion: Therefore, our study results suggest that the KA approach can be considered in patients using generic instruments with varus alignment of the knee, particularly those with mCPAK type I and IV varus knees, to help improve patient satisfaction. [ABSTRACT FROM AUTHOR]

Background and Objectives: There is an ongoing discussion about the best alignment targets in total knee arthroplasty (TKA). Mechanical alignment has been the standard in TKA for years. Alongside the development of various classification systems to describe the native alignment of the knee (knee phenotype), kinematic alignment restoring the individual phenotype of the knee has been advocated more recently. Alignment in TKA becomes even more challenging in knees with preoperative deformities such as valgus osteoarthritis. Materials and Methods: The study retrospectively evaluated 158 knees in 135 patients who underwent TKA with a mechanical alignment target for valgus osteoarthritis. Pre- and postoperative hip knee angle, lateral distal femur angle, and medial proximal tibial angle/tibial plate angle (pre-/postoperative) were measured on standing hip-to-ankle radiographs. Knees were grouped according to the coronal plane alignment of the knee (CPAK) classification. Preoperative and postoperative range of motion and patient-related outcome measures (WOMAC, UCLA, SF-12, pain) were assessed. Results: There was no difference in outcome for mechanically aligned TKA between the different CPAK phenotypes, suggesting that mechanical alignment is an appropriate target for the different phenotypes analyzed in the study. Remaining valgus alignment was associated with decreased postoperative UCLA scores and decreased improvement in SF-12 scores (p = 0.011/p = 0.028). Within CPAK III, mechanical aligned TKA showed better postoperative UCLA Scores than TKA with valgus alignment (p = 0.015). The individual knee phenotype in patients with valgus osteoarthritis did not influence the outcome of mechanical aligned TKA operated with standardized soft-tissue release. [ABSTRACT FROM AUTHOR]

Purpose: The decision on which technique to perform a total knee arthroplasty (TKA) has become more complicated over the last decade. Perceived limitations of mechanical alignment (MA) and kinematic alignment (KA) have led to the development of the functional alignment (FA) philosophy. This study aims to report the 2-year results of an initial patient cohort in terms of revision rate, PROMs and complications for Computer Aided Surgery (CAS) Navigated FA TKA. Methods: This paper reports a single surgeon's outcomes of 165 consecutive CAS FA TKAs. The final follow-up was 24 months. Pre-operative and post-operative patient-reported outcome measures, WOMAC and KSS, and intra-operative CAS data, including alignment, kinematic curves, and gaps, are reported. Stress kinematic curves were analysed for correlation with CAS final alignment and CAS final alignment with radiographic long-leg alignment. Pre- and post-operative CPAK and knee phenotypes were recorded. Three different types of prostheses from two manufacturers were used, and outcomes were compared. Soft tissue releases, revision and complication data are also reported. Results: Mean pre-operative WOMAC was 48.8 and 1.2 at the time of the final follow-up. KSS was 48.8 and 93.7, respectively. Pre- and post-operative range of motion was 118.6° and 120.1°, respectively. Pre-operative and final kinematic curve prediction had an accuracy of 91.8%. CAS data pre-operative stress alignment and final alignment strongly correlate in extension and flexion, r = 0.926 and 0.856, p < 0.001. No statistical outcome difference was detected between the types of prostheses. 14.5% of patients required soft tissue release, with the lateral release (50%) and posterior capsule (29%) being the most common. Conclusion: CAS FA TKA in this cohort proved to be a predictable, reliable, and reproducible technique with acceptable short-term revision rates and high PROMs. FA can account for extremes in individual patient bony morphology and achieve desired gap and kinematic targets with soft tissue releases required in only 14.5% of patients. Level of evidence: IV (retrospective case series review). [ABSTRACT FROM AUTHOR]

Purpose: Assessment of the conventional mechanical axis (MA) (hip-to-talus axis) is reported to result in constitutional varus in the native knee. However, the ground MA (hip-to-calcaneus axis), which is the line from the hip center to the bottom of the calcaneus, passes through the center of the knee joint in the native knee and is a possible alternative target for total knee arthroplasty (TKA) assessments. Therefore, this study aimed to present a "ground kinematically aligned (KA)-TKA." In this technique, the femoral component is placed on the cylindrical axis using the calipered technique and the tibial component is placed to give a neutral ground MA. Radiographical investigation was used to determine whether physiological alignment can be individually achieved with ground KA-TKA; this was compared with that of a tibia-restricted modified KA-TKA, referring to conventional MA (hip-to-talus axis) results. Methods: As the primary endpoint, this prospective cohort study compared the ground MA ratios of the knee joints in 40 ground KA-TKAs (G group: Coronal Plain Alignment of the Knee (CPAK) 28 type I, 7 II, 1 IV, and 4 V) with those of the preceding 60 modified KA-TKAs (M group: CPAK 46 type I, 12 II, and 2 V) performed for patients with varus osteoarthritis (OA). The number of outliers differing over ± 5% from the neutral were compared between groups using the χ2-test. The Hip–knee–ankle (HKA) angle, coronal femoral/tibial component alignment (FCA/TCA), and joint line orientation angle (JLOA) were compared between the groups using non-paired t-tests. Statistical significance was set at p < 0.05. Results: The G group had a higher ratio of the ground MA passing through the knee center than the M group did; outliers differing over ± 5% from the neutral of the ground MA were 2/40 cases in the G group and 20/60 cases in the M group, which was a significant difference (p = 0.001). The HKA angle, FCA/TCA, and JLOA were not significantly different between the groups. Conclusions: Targeting the ground MA in KA-TKA for patients with varus OA was feasible and has the potential to provide a physiological alignment more similar to the native knee in TKA than other kinematic alignment techniques. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

PurposeLower limb malalignment is a strong predictor of progression in knee osteoarthritis. The purpose of this study is to identify the individual alignment variables that predict progression in early to moderate osteoarthritis of the knee.MethodA longitudinal cohort study using data from the Osteoarthritis Initiative. In total, 955 individuals (1329 knees) with early to moderate osteoarthritis (Kellgren-Lawrence grade 1, 2 or 3) were identified. All subjects had full-limb radiographs analysed using the Osteotomy module within Medicad® Classic (Hectec GMBH) to give a series of individual alignment variables relevant to the coronal alignment of the lower limb. Logistic regression models, with generalised estimating equations were used to identify which of these individual alignment variables predict symptom worsening (WOMAC score > 9 points) and or structural progression (joint space narrowing progression in the medial compartment > 0.7mm) over 24 months.ResultsIndividual alignment variable were associated with both valgus and varus alignment (mechanical Lateral Distal Femoral Angle, Medial Proximal Tibial Angle and mechanical Lateral Distal Tibial Angle). Only the Medial Proximal Tibial Angle was significantly associated with structural progression and none of the variables was associated with symptom progression. The odds of joint space narrowing progression in the medial compartment occurring at 24 months increased by 21% for every one degree decrease (more varus) in Medial Proximal Tibial Angle (p < 0.001) CONCLUSIONS: Our results suggest that the risk of structural progression in the medial compartment is associated with greater varus alignment of the proximal tibia.Level of evidenceLevel III, retrospective cohort study.

Abstract Background Mechanically aligned total knee arthroplasty (MATKA) is a well-established procedure. Kinematically aligned TKA (KATKA) has been proposed to restore and preserve pre-arthritic knee anatomy. However, normal knee anatomy varies widely, and there have been concerns regarding restoring unusual anatomy. Accordingly, restricted KATKA (rKATKA) was introduced to reproduce constitutional knee anatomy within a safe range. This network meta-analysis (NMA) aimed to evaluate the clinical and radiological outcomes of the surgeries. Methods We performed a database search on August 20, 2022, which included randomized controlled trials (RCTs) comparing any two of the three surgical TKA techniques for knee osteoarthritis. We conducted a random-effects NMA within the frequentist framework and evaluated confidence in each outcome using the Confidence in Network Meta-Analysis tool. Results Ten RCTs with 1,008 knees and a median follow-up period of 1.5 years were included. The three methods might result in little to no difference in range of motion (ROM) between methods. In patient-reported outcome measures (PROMs), the KATKA might result in a slight improvement compared with the MATKA (standardized mean difference, 0.47; 95% confidence interval [CI], 0.16–0.78; very low confidence). There was little to no difference in revision risk between MATKA and KATKA. KATKA and rKATKA showed a slight valgus femoral component (mean difference [MD], -1.35; 95% CI, -1.95–[-0.75]; very low confidence; and MD, -1.72; 95% CI, -2.63–[-0.81]; very low confidence, respectively) and a slight varus tibial component (MD, 2.23; 95% CI, 1.22–3.24; very low confidence; and MD, 1.25; 95% CI, 0.01–2.49; very low confidence, respectively) compared with MATKA. Tibial component inclination and hip–knee–ankle angle might result in little to no difference between the three procedures. Conclusions KATKA and rKATKA showed similar ROM and PROMs and a slight variation in the coronal component alignment compared with MATKA. KATKA and rKATKA are acceptable methods in short- to mid-term follow-up periods. However, long-term clinical results in patients with severe varus deformity are still lacking. Surgeons should choose surgical procedures carefully. Further trials are warranted to evaluate the efficacy, safety, and subsequent revision risk.