Knee Surgery and Related Research最新文献

Background: The choice between simultaneous and staged bilateral total knee arthroplasty (TKA) remains controversial due to safety and resource considerations. This meta-analysis compared outcomes between the two approaches.

Methods: A total of 42 comparative studies published from 2001 to 2025 were included. A combined population of 567,915 patients was analyzed, with 225,181 undergoing simultaneous and 342,734 staged bilateral TKA. Random- or fixed-effects models were used to pool data across multiple clinical end points. Outcomes included in-hospital, first-year, and 1-2-year complications, mortality, functional outcomes, reoperations, persistent pain, and healthcare utilization metrics. Effect estimates were summarized using odds ratios (OR) for dichotomous outcomes and mean differences (MD) or standardized mean differences (SMD) for continuous outcomes, all with 95% confidence intervals (CI).

Results: Simultaneous TKA was associated with significantly higher odds of transfusion (OR 3.99; 95% CI 3.10-5.13; p < 0.001), first-year neurological complications (OR 1.48; 95% CI .128-1.71; p < 0.001), and first-year mortality (OR 2.43; 95% CI 2.02-2.92; p < 0.001). Pulmonary complications were significantly higher between 1 and 2 years postoperatively (OR 1.41; 95% CI 1.11-1.80; p = 0.005). However, joint infection (in-hospital, OR 0.59; 95% CI 0.40-0.89; p = 0.01), first-year periprosthetic fracture (OR 0.46; 95% CI 0.38-0.57; p < 0.001), and overall reoperation rates (OR 0.65; 95% CI 0.61-0.69; p < 0.001) were significantly lower in the simultaneous group. No significant differences were observed in functional scores, persistent pain, arthrofibrosis, knee instability, or extensor mechanism failure (p > 0.05). Simultaneous procedures were also associated with shorter operative times (MD -66.83 min; 95% CI -91.80 to -41.86; p < 0.001) and lower in-hospital costs (MD -$7062.67; 95% CI -13,927.78 to -197.56; p = 0.04).

Conclusions: Simultaneous bilateral TKA offers advantages in operative efficiency, cost reduction, and lower reoperation and fracture rates, but carries increased odds of neurological complications, transfusion, and early mortality. Careful patient selection and perioperative management are essential to balance these trade-offs when considering simultaneous procedures.

Background: Artificial intelligence (AI), including machine learning (ML) and deep learning (DL), is increasingly being integrated into total knee arthroplasty (TKA) to improve accuracy, efficiency, and personalized care. These technologies enable the analysis of large, complex datasets to support evidence-based clinical decision-making across all phases of the surgical process.

Main body: AI has demonstrated utility in multiple stages of TKA. In patient selection, ML algorithms can predict postoperative complications such as transfusion needs with high accuracy (AUC up to 0.842). For preoperative planning, DL techniques facilitate 3D anatomical reconstruction and implant size prediction, with some models achieving over 90% accuracy for exact component sizing, significantly outperforming traditional 2D templating. Intraoperatively, AI-assisted robotic systems and sensor technologies offer real-time feedback on alignment and soft tissue balancing. Postoperatively, AI-integrated wearable devices and mobile applications enable continuous monitoring and tailored rehabilitation; in some randomized trials, these tools have been associated with a statistically significant reduction in hospital readmission rates. Despite these advances, significant challenges remain, including algorithmic bias, a lack of model generalizability and explainability, and unresolved ethical and regulatory hurdles that present formidable barriers to widespread clinical implementation.

Conclusions: AI has the potential to significantly reshape TKA by enabling more precise, data-driven, and patient-centered care. However, its promise is contingent on overcoming critical limitations. Broader implementation requires robust multicenter validation to ensure model reliability, the development of explainable algorithms to build clinical trust, and a commitment to responsible innovation. With continued progress, AI can serve as a powerful complementary tool to augment surgical expertise and enhance patient outcomes in orthopedic surgery.

Purpose: To analyze the correlation and degree of agreement between the patellar heights measured at knee flexion of 0° and 30° before and after total knee arthroplasties (TKA) without patellar resurfacing.

Methods: One hundred primary TKAs with nonresurfaced patella were prospectively evaluated. We measured the Insall-Salvati ratio (ISR), modified ISR (mISR), Blackburne-Peel ratio (BPR), and Caton-Deschamps ratio (CDR) in weightbearing true lateral radiograph at knee flexion of 0° and 30°. The correlations between the patellar height measured at knee flexion of 0° and 30° were analyzed by Pearson correlation analysis. The degree of agreement between the patellar heights in knee flexion angles of 0° and 30° was analyzed using the limits of agreement (LoA) of Bland-Altman analysis; a difference of <  ± 0.2 between the measurements at knee flexion of 0° and 30° was deemed clinically acceptable.

Results: Very strong correlations existed between the pre- and postoperative ISR (r = 0.826 and 0.823, p < 0.001, respectively), and the preoperative mISR (r = 0.802, p < 0.001) measured between knee flexion angles of 0° and 30°. Strong correlation was observed in the other pre- and postoperative measurements. The range between upper and lower LoAs of the ISR measured at knee flexion of 0° and 30° was <  ± 0.20 preoperatively (-0.174 ~ 0.155) and postoperatively (-0.181 ~ 0.174), while the ranges for all other measurements did not lie within the clinically acceptable range.

Conclusions: The ISR measured at 0° or 30° of knee flexion during weightbearing can be interchanged reasonably before and after TKA. Although knee flexion of 30° is the standard, lateral radiograph of 0° flexion can be a reasonable alternative for evaluating patellar height using the ISR.

Level of evidence: Level II.

Background: Patellar instability is a multifactorial condition with varying severity, categorized into single-episode, recurrent, and habitual dislocations. This study aims to assess the association and the strength of association between clinical subtypes of patellofemoral instability (PFI) (single-episode, recurrent, and habitual patellar dislocation) and the frequency, severity, and cumulative presence of three key radiological risk factors: trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, and the Caton-Deschamps (CD) ratio.

Methods: This was a retrospective observational study conducted from January 2018 to December 2024 on 106 patients reported in the outpatient department (OPD) with various type of patellar instability (124 knees; 39 knee SPD, 73 knee RPD, and 12 knee HPD). Three radiological parameters (trochlear dysplasia, tibial tuberosity-trochlear groove (TT-TG) distance with > 15 mm defined as high), and Caton-Deschamps (CD) ratio (> 1.2 indicating patella alta) were evaluated using magnetic resonance imaging (MRI). Chi-squared test and Cramér's V statistical methods were applied for analyzing the strength of association.

Results: The study identified prevalence of trochlear dysplasia in 63.7%, high TT-TG distance in 32.2%, and patella alta in 45.2% of knees with varying types of patellar instability. Trochlear dysplasia showed the strongest association, particularly with habitual dislocations (100%). Prevalence of high TT-TG progressively increased from single-episode (17.9%) to recurrent (32.9%) to habitual patella dislocation (75%). In contrast to trochlear dysplasia and high TT-TG distance, patella alta was found to have a weaker association in characterizing the patellar instability. Notable, correlation was observed with severity of patellar instability and the number of risk factors, with cases with habitual patella dislocation most frequently showing multiple contributing factors.

Conclusions: Our study found that patients with HPD, the most severe clinical form of patellar instability, had pronounced trochlear dysplasia, higher TT-TG distance, and a greater number of radiological risk factors, followed by RPD and finally SPD. Among the parameters, trochlear dysplasia and TT-TG distance showed stronger association with clinical types, while patella alta had a weaker correlation.

Soft-tissue balancing is essential for achieving optimal outcomes in total knee arthroplasty (TKA), significantly impacting postoperative joint function, patient satisfaction, and implant longevity. Despite advancements in surgical techniques, traditional methods for evaluating soft-tissue tension remain largely subjective, leading to inconsistent outcomes and patient dissatisfaction. Recent technological developments, particularly the integration of digital devices, have shown promise in transforming soft-tissue balancing from a subjective art into a reproducible science. This manuscript is a narrative review that systematically summarizes the historical and technological evolution of soft-tissue tension gauging methods in TKA, encompassing experiential methods, mechanical tensors, and contemporary digital sensors. We critically discuss the strengths, limitations, and available clinical evidence for each method. Furthermore, this review highlights the integration of robotic systems and provides insights into future translational strategies, emphasizing artificial-intelligence-driven personalized soft-tissue balancing as a promising therapeutic direction. This review further comprehensively discusses soft-tissue tension gauging methods in TKA, providing a clear understanding of their evolution from subjective assessments to objective digital technologies. This study provides a robust theoretical foundation for the clinical application of digital tensors and robotic technologies. Integrating these technologies with artificial intelligence can effectively transform soft-tissue balancing strategies, thereby enhancing surgical precision, patient satisfaction, and clinical outcomes in TKA.

Background: Meniscal allograft transplantation (MAT) and autologous chondrocyte implantation (ACI) are well-established procedures. However, evidence regarding the safety and efficacy of their combined application remains inconclusive. Thus, the present systematic review aimed to comprehensively evaluate the existing literature on clinical outcomes after combined MAT and ACI.

Methods: A comprehensive search of clinical studies reporting on clinical outcomes after combined MAT and ACI was performed across three databases in accordance with the review protocol. Key demographic data, surgical technique, knee-specific patient-reported outcome measures, failure rates, and reoperation rates were extracted from eligible studies and analyzed. Risk of bias was assessed using the Methodological Index for Non-Randomized Studies (MINORS).

Results: The search yielded 246 studies, 9 of which satisfied inclusion and exclusion criteria, comprising 155 patients undergoing combined MAT and ACI at an average age of 36.1 years. The mean follow-up duration was 5.3 years (2.0-12.9 years). Clinical outcome measures improved across all studies (with one exception in a single outcome measure); statistical significance was shown in six out of seven studies reporting significance analysis. International Knee Documentation Committee (IKDC) scores were reported by four studies, showing an average improvement of 22.0 points. Lysholm scores showed an average improvement of 20.0 points across five studies. Of five studies comparing combined procedures with isolated procedures, one comparative study and one literature comparison reported inferior outcomes after combined surgery, while one subgroup analysis and two literature comparisons found comparable outcomes. Failure rates ranged from 0.0% to 52.6%, with significant methodological heterogeneity. The mean reoperation rate was 35.0% across seven studies.

Conclusions: Combined MAT and ACI leads to meaningful improvements in clinical outcomes, with notable failure and reoperation rates. While some studies suggest outcomes may be comparable or inferior to isolated procedures, only one study directly assessed this. As such, definitive conclusions cannot be drawn. Combined MAT and ACI can be considered as a viable option in select patients, but realistic expectations must be ensured.

Background: Implant design in total knee arthroplasty (TKA) has evolved considerably, with recent developments focusing on reproducing native knee kinematics. Some implants now feature anatomically and physiologically accurate articular surface geometries. This study aimed to evaluate the impact of different implant designs on knee kinematics using the same cadaveric specimens to ensure consistent comparison. We hypothesized that implant designs incorporating features intended to replicate native joint anatomy, such as the kinematic retaining (KR) design, would more closely reproduce physiological knee kinematics.

Methods: TKA was performed on nine Thiel-embalmed cadaveric knees with mild medial osteoarthritis, using three implant designs from the Physica system: KR, cruciate retaining (CR), and medial congruent (MC) designs. All procedures were performed using a mechanical alignment technique, with both the posterior tibial slope and femoral rotational angle standardized at 3°. The posterior cruciate ligament was preserved throughout the evaluation of all implant designs. A navigation system was used to collect detailed kinematic data. Evaluations were conducted after trial component placement, focusing on anteroposterior, mediolateral, and compression-distraction positions, as well as rotational angles. From these knee status data, femoral rotational kinematics relative to the tibia and the anteroposterior translation of both femoral condyles during flexion were also calculated.

Results: No significant differences in flexion and extension angles were observed between the groups. The KR group presented the greatest mean femoral external rotation relative to the tibia throughout the range of motion among the groups; however, there were no statistically significant differences. The CR and MC group showed significantly reduced anteroposterior translation of the lateral condyle compared with the native knee (p = 0.021 and 0.003, respectively). Furthermore, the anteroposterior translation of the lateral femoral condyle was significantly greater in the KR group than in MC groups (p = 0.021). In the KR group, six of nine knees exhibited medial pivot motion, compared with three in the CR group and four in the MC group.

Conclusions: Using identical cadaveric specimens and navigation-based analysis, we identified distinct kinematic profiles associated with each implant design. Notably, the KR implant demonstrated kinematics approximating native knee motion; however, these findings remain preliminary and warrant further clinical validation.

Level of evidence: III.

Background: A clear understanding of minimal clinically important difference (MCID) and substantial clinical benefit (SCB) is essential for effectively implementing patient-reported outcome measurements (PROMs) as a performance measure for total knee arthroplasty (TKA). Since not achieving MCID and SCB may reflect suboptimal surgical benefit, the primary aim of this study was to use machine learning to predict patients who may not achieve the threshold-based outcomes (i.e., MCID and SCB) on the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) following TKA.

Methods: Data from 1064 patients who underwent TKA at a single academic medical center between 2016 and 2022 contained 81 preoperative variables, including routinely collected measures and PROMs (KOOS JR and Patient-Reported Outcomes Measurement Information Systems [PROMIS-10]). Several machine-learning models were developed, which include penalized logistic regression as a linear model, support vector machine with polynomial and radial kernels as nonlinear models, and random forest and extreme gradient boosting as nonparametric models. These models predicted both distribution- and anchor-based MCIDs and SCB. In addition, logistic regression models were used to identify relevant risk factors for failing to meet these thresholds.

Results: The random forest models and the penalized logistic regression models achieved acceptable area under the receiver operating characteristic curve (AUC) close to or above 0.7 for all the outcomes. Furthermore, the logistic regression models identified shared risk factors for the three outcomes: preoperative PROMs (i.e., KOOS JR score, PROMIS-10 global physical T-score, and PROMIS-10 general mental health), antidepressant medication history, age, and Kellgren-Lawrence grade.

Conclusions: Machine-learning models were able to identify patients at risk of failure to achieve the threshold-based metrics and relevant preoperative factors. As such, these models may be used to both improve shared decision-making and help create risk-stratification tools to improve quality assessment of surgical outcomes.

Background: Surgical interventions to correct abnormal quadriceps direction are performed in cases of patellofemoral joint disorders, to medialize the patella and reduce lateral stress. However, excessive medialization can lead to increased contact forces and joint instability, underscoring the need for a more detailed understanding of the effects of quadriceps alterations on joint biomechanics. The purpose of this study was to evaluate the impact of variations of the magnitude and direction of the quadriceps force on the kinematics of the patellofemoral joint.

Methods: A total of 12 cadaveric knees were evaluated in flexion-extension applying different loads to the quadriceps tendon. Specifically, we evaluated five different directions of the quadriceps line of action in the frontal plane: neutral, ±6° and ±12°; and two directions in the sagittal plane: neutral and 5° anterior. Three load magnitudes were simulated: 20 N, 160 N, and 280 N. Relative motion between the patella, femur, and tibia was measured using an optoelectronic system.

Results: The comparison under reference loading conditions (neutral direction, 20 N) across all specimens demonstrated consistent patellofemoral motion. Similarly, tibiofemoral kinematics was comparable between specimens and with the literature. Variations of the direction of the quadriceps force in the frontal plane exerted a significant impact on all components of motion in the patellofemoral joint. Compared with the reference condition, at full extension, 12° medialization increased patellar varus rotation (-6.2° ± 3.3°), while at high flexion it increased valgus rotation (4.8° ± 4.8°). Lateralization reversed this pattern, causing valgus at extension (7.7° ± 3.6°) and varus in flexion (-2.8° ± 1.8°). Medial-lateral patellar translation exceeded ±6 mm under 12° deviations. Sagittal-plane changes had minimal impact, mostly in extension when the patella is not yet in the trochlea. Tibiofemoral kinematics was more sensitive to load magnitude, although frontal-plane direction also affected joint rotation.

Conclusions: This study provides essential insights into the biomechanical interplay between quadriceps alignment and patellofemoral kinematics. These findings may inform surgical strategies for optimizing patellar tracking. Level of evidence In vitro biomechanical tests.