Knee Surgery and Related Research最新文献

Background: Accurate measurement of posterior tibial slope (PTS) is highly sensitive to axial malrotation of the knee during acquisition, but its impact has not been systematically quantified across different anatomical variations. This simulation study aimed to quantify the effect of axial malrotation on PTS using digitally reconstructed radiographs (DRRs) and suggest a practical marker for filtering out low-quality images with excessive malrotation.

Materials and methods: A total of 55 preoperative computed tomography (CT) scans from January 2021 to December 2024 in a single, tertiary hospital were retrospectively reviewed. DRRs were generated from those scans to simulate lateral knee radiographs with malrotation ranging from -12° to +12° relative to an anatomically aligned baseline. An artificial-intelligence (AI)-based tool automatically measured PTS on each DRR, with agreement evaluated using intraclass correlation coefficient (ICC). PCDR was calculated from femoral contours and analyzed for correlation with malrotation angles and resulting PTS measurement error.

Results: AI-based PTS measurements on DRRs showed good agreement with expert annotations (ICC = 0.78, 95% CI 0.73-0.82). PTS increased linearly with internal rotation, with each 1° of rotation resulting in approximately 0.2° change in PTS (R² = 0.43, p < 0.01). Errors exceeded 1° when malrotation surpassed ±6°. PCDR was strongly correlated with malrotation angle (R² > 0.98, p < 0.001) and achieved fair discriminative performance as a binary classifier for > 1° PTS error [area under the receiver operating curve (AUROC) = 0.77].

Conclusions: CT-derived DRRs combined with AI analysis showed that PTS measurement error proportionately increased with axial malrotation. Identifying and excluding radiographs with excessive rotation improves the reliability of slope-based assessments and supports more accurate surgical planning.

Level of evidence: III, retrospective cohort study.

Total knee arthroplasty (TKA) is a widely performed procedure for end-stage arthritis, with cemented fixation historically dominating owing to its immediate stability and ability to compensate for minor bone defects. However, concerns over the long-term durability of cemented implants, particularly in younger and more active patients, have renewed interest in cementless TKA as a viable alternative. Advances in implant design, including hydroxyapatite coatings and porous metal surfaces, have improved clinical outcomes, reducing early loosening and enhancing biological fixation. Proper patient selection is crucial for the success of cementless TKA. Studies suggest that younger patients, those with good bone quality, and even some elderly or obese individuals may benefit from cementless implants. While initial migration of the tibial component is more pronounced in cementless TKA, research indicates that this stabilizes over time without impacting long-term outcomes. In addition, pharmacologic interventions, such as bisphosphonates and teriparatide, may help enhance periprosthetic bone density and implant fixation. Despite promising results, challenges remain, particularly in patients with osteoporosis, rheumatoid arthritis, and smoking-related bone health issues. Further research is needed to refine selection criteria, optimize surgical techniques, and ensure long-term success. As next-generation cementless implants continue to evolve, ongoing studies will be essential in guiding patient management strategies for improved outcomes.

Background: Meniscal injuries are commonly observed in acute anterior cruciate ligament (ACL) injuries, with varying reports on the incidence and location of meniscal tears. In particular, the incidence of posterior menisco-capsular tears may have been underestimated in previous literature owing to the technical challenges associated with posterior arthroscopic evaluation. This study aimed to determine the true incidence and location of posterior menisco-capsular junction tears in patients undergoing anterior cruciate ligament reconstruction (ACLR) up to 6 weeks of injury, hypothesizing a higher incidence than previously reported.

Methods: A retrospective analysis was conducted on patients who underwent primary ACLR between July 2015 and January 2023, including a total of 139 patients. Arthroscopic findings and surgical records were reviewed, and the posteromedial and posterolateral joint spaces were evaluated via intercondylar notch view with a 70-degree arthroscope or via a posteromedial/posterolateral portal as a viewing portal to confirm posterior menisco-capsular junctional tears in all patients. The Cooper's classification system was used to document tear locations, and radial and longitudinal tear components were analyzed.

Results: Meniscal tears were observed in 104 patients (74.8%). Medial meniscus tears occurred in 63 patients (45.3%), while lateral meniscus tears were found in 78 patients (56.1%). Bilateral meniscus tears were identified in 37 patients (26.6%). Radial tears were predominantly observed in the lateral meniscus (22.3%), with a significant portion being lateral meniscus root tears (15.1%). Longitudinal tears, particularly at the menisco-capsular junction, were the most common tear pattern, occurring in 64.7% of patients.The most commonly involved tear sites were Zone A0 (39.6%) and Zone A1 (42.4%) in the medial meniscus, and Zone F0 (36.7%) and Zone F1 (38.1%) in the lateral meniscus.

Conclusions: Longitudinal tears at the menisco-capsular junction are the most common tear pattern in acute ACL injuries, revealing a higher incidence than previously reported. In acute ACL injuries, Zones A0-A1 and F0-F1 should be meticulously evaluated using an intercondylar notch view with a 70-degree arthroscope or via a posteromedial/posterolateral portal as a viewing portal.

Background: Unicompartmental knee arthroplasty (UKA) is a common treatment for medial osteoarthritis, providing faster recovery and better joint kinematics than total knee arthroplasty (TKA). However, periprosthetic tibial plateau fractures (TPF) remain a significant complication. Undersized tibial components, especially size AA, increase TPF risk. This study aims to examine the biomechanical relation between tibial implant size and the risk of periprosthetic fractures.

Methods: A biomechanical study was conducted using 16 customized synthetic bone models to simulate the effects of tibial component sizing in UKA. Proximal tibial models with components of size A and size AA were subjected to axial loading, and the maximum load to failure and cycles to failure were measured for each size. Additionally, plastic axial deformation was calculated at the maximum load level of the weakest construct. Strain patterns were compared with clinically observed fracture lines reported in previous studies.

Results: Size AA had a significantly lower maximum load and cycles to failure compared with size A (1039 N ± 75 N and 9.336 ± 925 cycles versus 1140 N ± 83 N and 8.326 ± 759 cycles, p = 0.031). The strain patterns were consistent with those observed in clinical studies, showing a wedge-shaped distribution from the posteromedial to the anteromedial tibial plateau. Plastic deformation was less than 0.6 mm across all specimens, with no significant difference in axial displacement between the two groups (p = 0.64).

Conclusion: Undersizing the tibial component reduces load-bearing capacity of the tibial plateau and thereby increases the risk of periprosthetic fractures. Precise implant sizing by correct sagittal resection is essential to minimize the risk of fracture in UKA.

Experimental study: Type V.

Background: Bone irrigation is a crucial step in cemented total knee arthroplasty procedures to promote maximal cement penetration and interdigitation into the cancellous bone. However, it is not clear which type of bone irrigation achieves the best results. This study aimed to compare the efficacy of high-pressure pulsatile lavage versus manual rinsing in promoting bone cement penetration during total knee arthroplasty.

Methods: We conducted a single-center, prospective, randomized, controlled clinical trial in 100 patients undergoing primary total knee arthroplasty during 1 year. All patients were randomly allocated to either the pulsed lavage group or the non-pulsed lavage group. We assessed total cement penetration depth across all zones radiologically using anteroposterior and lateral radiographic views in postoperative X-rays taken on the first day after surgery and segmenting them into ten zones according to the Knee Society Scoring System (KSSS).

Results: The patient cohort included 100 individuals with an average age of 75 years (standard deviation [SD] 5.7); 73% were female. The mean total bone cement penetration values in both anteroposterior (AP) and lateral views were 10.77 mm (SD 5.95) and 4.85 mm (SD 3.33) for manual lavage, and 11.34 mm (SD 6.26) and 5.23 mm (SD 3.50) for pressurized lavage. We observed no significant differences between the two groups after adjusting for multiple variables.

Conclusions: High-pressure pulsatile lavage showed no significant differences in enhancing bone cement penetration compared with manual lavage as measured by the KSSS total knee arthroplasty bone cementation scale in X-rays taken on the first postoperative day. Level of Evidence Level I-Therapeutic randomized controlled trial. Trial registration Clinicaltrials.gov Register-NCT06032507.

Background: Although both unicompartmental knee arthroplasty (UKA) and medial open-wedge high tibial osteotomy (MOWHTO) are widely accepted surgical options for medial compartment osteoarthritis, there is limited evidence from long-term outcomes to confirm and refine their established indications. This study aimed to evaluate the long-term clinical and radiologic outcomes of UKA and MOWHTO when performed according to their established indications at a single institution, and to characterize the demographic and preoperative radiographic differences associated with surgical selection.

Methods: Patients who underwent UKA or MOWHTO for medial compartmental OA with a minimum 10-year follow-up were retrospectively reviewed. Preoperative characteristics, including age and the degree of medial OA using Kellgren-Lawrence grading, clinical outcomes, and radiologic parameters, including hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and OA progression in the patellofemoral compartment, were compared. Survivorship based on the conversion to total knee arthroplasty was also evaluated.

Results: The current study included 79 UKAs and 140 MOWHTOs with a mean 13.2 ± 1.7 years follow-up. Preoperatively, the UKA group had significantly older age (P < 0.001) and more advanced degree of medial OA (P < 0.001) than the MOWHTO group. Postoperative clinical outcomes were not significantly different between the groups. Radiologically, the UKA group had significantly less varus alignment and larger MPTA than the MOWHTO group (all, P < 0.001). Although the proportion of OA progression in the patellofemoral joint was higher in the MOWHTO group than in the UKA group at the latest follow-up (P = 0.012), there was no significant difference in anterior knee pain. At the mean 13-year follow-up, survival rates were not significantly different between the UKA (96.2%) and MOWHTO (98.6%) groups.

Conclusions: Both UKA and MOWHTO demonstrated excellent long-term outcomes when performed under their established indications for medial compartment OA. Patients selected for UKA were older, had more advanced OA, less varus alignment, and a larger MPTA compared with those undergoing MOWHTO, consistent with published selection criteria. Radiographic progression of patellofemoral arthritis occurred more frequently after MOWHTO than after UKA, although this finding was not associated with clinical significance.

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.