BackgroundPosterior condylar offset (PCO) is a crucial knee anatomic parameter closely linked with joint function. Its restoration during posterior-stabilized total knee arthroplasty (TKA) draws wide research attention. Most studies focus on the impact of the PCO alterations on soft tissue balance and postoperative function, while relevant contributing factors remain poorly investigated.ObjectiveTo explore PCO variation after posterior-stabilized TKA and analyze potential influencing factors contributing to such changes.MethodsFrom November 2020 to November 2021, 146 consecutive participants with a diagnosis of severe knee osteoarthritis were enrolled for this prospective study. All participants underwent primary posterior-stabilized TKA utilizing 3D-printed patient-specific instrumentation. Perioperative clinical variables and radiographic parameters were assessed, and the osteotomy thickness in the posterior femoral condyle was quantified during the TKA procedure.ResultsA total of 134 participants (17 males and 117 females) were recruited in this prospective study, including 72 patients (53.7%) with changes of PCO after TKA < 3 mm in group 1, and 62 patients (46.3%) with changes of PCO after TKA ≥ 3 mm in group 2. The demographic characteristics, clinical scores, and radiographic measurements of the two groups were comparable before TKA. In general, postoperative PCO was considerably reduced compared with preoperative PCO (29.77 ± 3.52 mm vs. 27.67 ± 2.99 mm, p < 0.001). Postoperative PCO reduction was noted in 99 patients (73.9%). The correlation analysis indicated a relatively weak positive relationship between PCO variation and the osteotomy of posterior lateral femoral condyle (r = 0.282, p = 0.004). Moreover, radiographic evaluation revealed that patients in group 1 had a smaller preoperative posterior tibial slope (PTS, p < 0.001) and a smaller PTS change (p = 0.002) after TKA.ConclusionPCO tends to decrease after posterior-stabilized TKA. The osteotomy in posterior lateral femoral condyle may potentially serve as a direct influencing factor for such reduction. The preoperative PTS and a greater PTS change were found to be indirect influencing factors associated with PCO variability in posterior-stabilized TKA. These imply that the anatomical morphology in posterior femoral condyle should not be sacrificed for the pursuit of uniform femoral and tibial osteotomy concepts.

To establish an automated, landmark-based patellar coordinate system for standardized alignment, develop a patellar statistical shape model (SSM), and quantify 3D morphological variations associated with patellar dislocation (PD). Patellar surface models were reconstructed from CT/MRI scans of 54 participants (33 PD, 21 controls). An automated coordinate system was established and quantitatively validated. Demographic/morphometric risk factors were assessed using logistic regression. An SSM was built for the entire cohort, and principal component analysis (PCA) was used to extract major 3D shape modes. Between-group differences in PC scores were evaluated with multiple-testing control and covariate adjustment. A logistic regression classifier based on shape modes and demographics was evaluated using stratified 10-fold cross-validation. The automated coordinate system showed high repeatability. Patellar linear dimensions and centroid size did not differ between groups and were not independent predictors. Two robust shape modes differentiated PD from controls: PC4 (thickness/facet morphology) and PC7 (facet-edge morphology). A cross-validated classifier showed good in-cohort discrimination (mean AUC ≈ 0.91). In this cohort, PD was associated with localized 3D articular-surface shape patterns, characterized by a prominent medial facet, a flattened posterolateral facet, and accentuated facet margins, without corresponding differences in linear dimensions. The automated coordinate system and SSM provide a reproducible approach for quantitative patellar phenotyping. These shape modes may deepen understanding of PD pathomechanics and provide a quantitative basis for future, externally validated risk modeling in diverse populations.

Early viscoelastic deterioration of anterior cruciate ligament (ACL) reconstruction grafts impairs knee biomechanics and elevates osteoarthritis risk, with unclear mechanisms. We established a knee viscoelastic finite element model, set graft parameters at postoperative day 0 and 30 from animal data, and calculated joint stress under multiple loadings. By day 30, graft peak axial force dropped by 50%, causing abnormal stress redistribution. This study fills related research gaps and informs clinical rehabilitation and graft preparation.

The aim of this study is to evaluate and compare the performance of three non-rigid registration methods—coherent point drift (CPD), non-rigid iterative closest point (NRICP), and spherical parameterization—in building statistical shape models (SSMs) of femurs for identifying morphological features in patients with knee osteoarthritis (OA). A simplified femur template was selected. Non-rigid registration algorithms (CPD, NRICP, spherical parameterization) were applied to align the template surface to all other femur samples. The registration methods were assessed using multiple evaluation criteria: root mean square error (RMSE), Hausdorff distance (HD), computational efficiency, local deformation capability, outlier sensitivity, compactness, generalization, and specificity. The results showed that all deformable algorithms exhibited reasonable registration results. Among them, CPD performed best in RMSE, HD, local deformation, and specificity. Spherical parameterization balanced all these metrics but was unsuitable for handling abnormal structures and could occasionally result in severe reconstruction errors in complex anatomical structures. NRICP was the fastest technique with the lowest generalization reconstruction error but achieved the lowest registration accuracy. CPD is the most suitable method for accurate femur registration in SSMs, especially for detecting OA-related morphological variations. Spherical parameterization is a promising approach if it can mitigate extreme errors. NRICP favors efficiency over accuracy, suitable for real-time tasks.

It is known that open wedge high tibial osteotomy (OWHTO) may lead to progression of patellofemoral degeneration due to descent of the patellar height. However, the difference in patellofemoral joint (PFJ) loads with normal daily activity between uniplane and biplane osteotomies is unclear. The purpose of this study was to reveal the differences in PFJ biomechanics between uniplane and biplane OWHTO using finite element analysis (FEA). In this study, a finite element model of the knee joint was established using computed tomography (CT) and magnetic resonance imaging (MRI) data from a healthy volunteer, and a 10° varus deformity of the proximal tibia was simulated. Under the guidance of experienced orthopedic surgeons, simulations of both uniplane and biplane open wedge high tibial osteotomy procedures were conducted. The maximum stress and contact area of the PFJ at knee flexion angles of 90°, 60°, 30°, and 0° during sitting-to-standing and walking were measured in the three finite element models (normal knee joint model, uniplane OWHTO model, and biplane OWHTO model). In all models, the peak value of von-mises stress (VMS) occurred at 90 degrees of knee flexion. At 90 degrees of knee flexion, the biplane OWHTO model exhibited the highest PFJ stress, measuring 9.664 MPa. As the knee joint extended from 90 degrees of flexion to 0 degrees of extension, the PFJ stress gradually decreased in all three models. The decrease was most pronounced in the uniplane OWHTO model, although it remained higher than in the normal model. Uniplane OWHTO would induce lower contact stress and larger contact area on the patellofemoral surface than biplane OWHTO during walking and sitting-to-standing, which may cause less mechanical pain and secondary damage to the articular cartilage. Therefore, uniplane OWHTO might be a better option for patients with anterior knee pain and/or PFJ degeneration.

IntroductionOsteoarthritis (OA) is a heterogeneous whole-joint disease that inconveniences more than 500 million people worldwide. Early diagnostic methods for OA remain lacking. Peripheral blood mononuclear cells (PBMCs) are ideal sample sources for the early diagnosis of different diseases. However, only a few studies have reported on the role of PBMCs in the early diagnosis of OA.MethodsRNA sequencing was performed on PBMC samples from 27 patients with OA and 31 healthy controls. We integrated RNA sequencing data from our internal cohort and microarray data from external cohort to construct a diagnostic model of OA based on PBMC samples. The receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic model in PBMC samples and synovial tissue.ResultsIn this study, we screened and constructed a six-gene diagnostic model consisted of the genes THBS1, USP36, GIMAP4, OSM, IL10, and HDC, which could effectively distinguish patients with OA from healthy controls. The ROC curve analysis showed that the area under curve (AUC) of this diagnostic model was 0.928 for our internal cohort and 0.915 for the external cohort, respectively. Interestingly, the gene expression model also had high accuracy (AUC = 0.910) for diagnosing patients with OA based on expression data from synovial tissue.DiscussionGiven that related studies on several signature genes in our diagnostic model for OA are lacking, our study provides novel potential biomarkers for the early diagnosis of OA based on PBMC samples.

BACKGROUND:The lateral approach in total knee arthroplasty (TKA) is indicated primarily for patients with valgus knee deformity, as it allows direct access to the lateral anatomy and systematic correction of associated pathologies. SURGICAL TECHNIQUE:This technique involves strategic lateral soft tissue releases, which improve exposure to the posterolateral corner, enhance tibial rotation, and support patellar alignment without compromising medial vascularity or requiring a tibial tubercle osteotomy for joint exposure. Critical steps in the lateral TKA approach include maintaining a capsular-synovial overlap and preserving the Hoffa fat pad for optimal joint closure, releasing the lateral soft-tissue structures, and using a contralateral tibial cutting guide for enhanced access and protection of the patellar tendon. DISCUSSION:These techniques collectively allow for a balanced, stable joint with effective alignment and soft tissue management. Outcomes of the lateral approach in valgus TKA are comparable to those of the medial approach, with similar functional outcomes, range of motion, and surgical time. Some studies even report superior patellar tracking and function scores with the lateral approach. Complication rates are low, though attention is required to avoid peroneal nerve injury in severe deformities. Future research involving large, randomized controlled trials is recommended to substantiate these favorable outcomes and guide long-term treatment strategies for valgus TKA.

The elasticity and viscosity of the grafts are both crucial for joint stability, yet the changes trend in short-term following anterior cruciate ligament reconstruction (ACLR) remains unclear. The purpose of this study was to evaluate the short-term variations in graft elasticity and viscosity following ACLR. Sixteen male rabbits underwent ACLR using Achilles tendon graft. Animals were randomly euthanized 15 and 30 days following ACLR. The Young’s modulus and viscosity coefficient of the grafts were measured through uniaxial tensile and creep experiments. The cross-sectional area of the graft decreased mainly between day 15 and day 30 with no significant. The Young’s modulus decreased significantly between day 0 and day 15. while the decrease in viscosity coefficient significantly between day 0 and day 30. The average of uniaxial tensile Young’s moduli at day 0, 15, and 30 were 293.11 ± 42.58 MPa, 23.75 ± 6.62 MPa, and 9.02 ± 3.46 MPa, respectively, compared with 37.52 ± 6.12 MPa for the native ACL. The average of viscosity coefficients at 0, 15, and 30 days were 255.00 ± 55.06 MPa∙s, 205.56 ± 68 MPa∙s, and 58.06 ± 11.04 MPa∙s, compared with 159.54 ± 22.61 MPa∙s for the native ACL. Even the cross-sectional area, elasticity, and viscosity of grafts showed nonlinear decreasing trends in the short term after ACLR, but the patterns of decrease differ. These findings may serve as a reference for preoperative planning and postoperative rehabilitation.

Ten porcine tibiae were scanned by computed tomography (CT) and the three‑dimensional (3D)-printed navigation template for posterior cruciate ligament (PCL) reconstruction was designed using the Rhinoceros software. The outcomes of the control group and experimental group were obtained from the preoperative design and the navigation template, respectively. This paper focuses on evaluating the accuracy of the 3D-printed navigation template used to assist the anatomical location of tibial tunnel in PCL reconstruction in an in-vitro experimental study.

While venous thromboembolism (VTE) prophylaxis is crucial following major orthopaedic surgeries including total knee arthroplasty (TKA), the impact of different prophylactic agents on postoperative hemoglobin (Hb) levels remains inadequately studied. The aim of this study was to compare the effects of aspirin, rivaroxaban, and low-molecular-weight heparin (LMWH) on early postoperative Hb changes following TKA. In this single-center retrospective cohort study, 655 primary TKAs were finally included using data from the hospital information system. Patients received either aspirin, rivaroxaban, or LMWH for VTE prophylaxis. The primary outcome was the magnitude of Hb reduction, calculated as the difference between the Hb level on the first postoperative day and the minimum postoperative Hb level before discharge. The secondary outcome was the trajectory of postoperative Hb changes within the first week. Postoperative Hb levels clearly declined within the first week, with a mean of 13.9 g/L (SD, 8.5) from postoperative day 1 in the entire cohort. In the fully adjusted linear regression model, both rivaroxaban (β = 1.5, [95

Precise execution of preoperative 3D planning is critical in total knee arthroplasty (TKA), but current verification methods—postoperative imaging, navigation, robotics—have limitations: they often assess alignment indirectly or fail to directly compare planned and actual osteotomy surfaces. An in vivo method to quantitatively evaluate plan-execution discrepancies on resected surfaces is lacking. This study aimed to introduce a novel technique for acquiring the TKA osteotomy surface using intraoperative CT, and subsequently comparing it with the preoperative plan to accurately evaluate the precision of osteotomy. Furthermore, this technique was utilized to assess the reliability of osteotomy accuracy in patient-specific instrumentation (PSI) assisted TKA procedures. In this case series study, intraoperative CT scans were acquired immediately after bone resection in 80 TKAs. 3D models of the resected surfaces were created and precisely superimposed onto the preoperative 3D planning models. Angular discrepancies between planned and achieved osteotomy planes (coronal, sagittal, axial) for femur and tibia were quantified. Outliers (> 3°) were assessed. Excellent inter- and intra-observer reliability was confirmed, with Intra-class Correlation Coefficient (ICC) ranging from 0.807 to 0.959. Intraoperative CT verification demonstrated femoral deviations of 0.91° ± 0.71° (coronal plane, 2.5

Osteoarthritis (OA), a debilitating degenerative joint disease driven by chronic inflammation and cartilage degradation, remains inadequately addressed by current therapies. While mesenchymal stem cells (MSCs) offer regenerative potential, their clinical efficacy is hindered by poor survival, transient retention, and pathological joint microenvironments. Here, we present a bioengineered hydrogel-based stem cell niche (PPT hydrogel) that dynamically coordinates microenvironmental reprogramming and MSC functional redirection to achieve sustained OA treatment. The PPT platform integrates intrinsic antioxidative and anti-inflammatory properties to neutralize OA-associated oxidative stress and inflammation while enhancing bone marrow MSCs (BMSCs) survival via Hedgehog signaling activation, overcoming limitations of conventional cell delivery. By incorporating a pro-differentiation agent, PPT hydrogel steers BMSCs toward stable hyaline cartilage regeneration, suppressing the formation of fibrotic and hypertrophic cartilage even under inflammatory conditions. Furthermore, PPT amplifies BMSCs paracrine signaling to restore redox homeostasis and autophagy flux in resident chondrocytes through FOXO1-dependent mechanisms, establishing a self-reinforcing therapeutic loop. The modular amphiphilic design enables spatiotemporal co-delivery of diverse therapeutics, synergistically regulating stem cell behavior and host tissue responses. Through bridging stem cell-chondrocyte crosstalk, this multifaceted PPT hydrogel represents a transformative paradigm for precision regenerative medicine, offering a universally adaptable platform to address complex inflammatory and degenerative diseases beyond OA.

Background Previous studies have indicated that medial meniscal subluxation (MMS) is associated with special types of medial meniscus tears (MMT) and chondral lesions. However, most of these studies lacked arthroscopic findings and did not adjust for possible confounders. The purpose of this study was to explore factors associated with MMS in patients with MMT using multivariate logistic regression analysis. Methods A retrospective analysis of 115 patients who underwent arthroscopic surgery for MMT was conducted. The medial meniscal extrusion (MME) distance was measured on a single mid-coronal magnetic resonance (MR) image, and the MMS group included patients with MME distance ≥3 mm (55 patients with 55 knees). Other patients were included as the control group (60 patients with 60 knees). Demographic and clinical data were collected as variates. A multivariate logistic regression analysis was performed to identify factors associated with MMS. Results In a univariate analysis, the Outerbridge classification (P=0.002) and the type of MMT (P<0.001) were significantly different between the MMS group and the control group. According to unadjusted and age- and body mass index (BMI)-adjusted multivariate logistic regression analysis, the type of MMT was an independent factor associated with MMS. Compared with horizontal tears, radial tears, posterior medial meniscus root tears (PMMRT) and complex tears had approximately 6-fold (adjusted OR 6.468, 95% CI 1.509–27.718, P=0.012), 10-fold (adjusted OR 10.324, 95% CI 1.719–61.989, P=0.011) and 4-fold (adjusted OR 4.458, 95% CI 1.602–12.408, P=0.004) higher associations with MMS, respectively. Conclusion The type of MMT was an independent factor associated with MMS in knees with MMT. Radial tears, PMMRT and complex tears were more likely than horizontal tears to result in MMS. The results suggest that MMT combined with MMS should be noted when managing MMT, especially radial tears, PMMRT and complex tears. Moreover, the results indicate that we must not only preserve the meniscus as much as possible but also restore its position to as close to normal as possible.

[目的]探讨前参考系统全膝关节置换术(total knee arthroplasty,TKA)前侧皮质切割发生的相关因素.[方法]回顾性分析2015年10月-2020年12月在本院因原发性膝关节骨关节炎行前参考系统TKA的86例患者(105膝)连续病例资料.根据术后膝关节侧位X线片是否有前皮质切割表现,将患者分为切割组和未切割组.采用单因素分析和多因素逻辑回归分析前皮质切割发生的相关因素.[结果]105膝中,术后影像显示共28膝发生前皮质切割,占26.7％;77例未发生前皮质切割,占73.3％.前侧皮质切割者按Tayside分级,Ⅰ级13膝(12.4％),Ⅱ级10膝(9.5％),Ⅲ级5膝(4.8％),无Ⅳ级发生.单项因素比较,两组年龄、BMI、性别、侧别、前髁厚度、LDFA、MAD、前皮质屈曲角、髁间窝形态、前髁骨赘量、开髓点位置、股骨远端截骨量、后髁截骨量、通髁线辨认情况的差异均无统计学意义(P＞0.05).但是切割组术前后髁厚度显著大于未切割组(P＜0.05);切割组股骨假体选择偏小的比率显著高于未切割组(P＜0.05).多因素逻辑回归分析显示,术前影像测量后髁厚度大(OR=1.124;P＜0.05)是前皮质切割的危险因素,术中股骨假体选择偏大(OR=0.375;P＜0.05)是前皮质切割保护因素.[结论]在前参考系统TKA中,较大术前测量后髁厚度是前皮质切割的危险因素,而术中偏大的股骨假体选择是前皮质切割保护因素.

BACKGROUND:Early complications after arthroplasty for geriatric femoral neck fractures are known to negatively affect postoperative recovery and increase postoperative mortality. Identifying risk factors associated with early complications after arthroplasty may offer an opportunity to address and prevent these complications in many patients.OBJECTIVE:To evaluate preoperative risk factors for early complications after arthroplasty in elderly patients with a femoral neck fracture.METHODS:119 elderly patients with femoral neck fractures who had been treated with arthroplasty (hemiarthroplasty or total hip arthroplasty) between December 2015 and December 2018 were retrospectively analysed. Early complications were defined as any complications that did not exist preoperatively, and occurred during hospital stay after arthroplasty Preoperative clinical, epidemiological and laboratory data were collected. Binary univariable and multivariable logistic regression analysis were applied to identify predictors of early complications after arthroplasty for geriatric femoral neck fractures.RESULTS:Median age of all patients was 80.0 (IQR 74.0-84.0) years. We identified 28 (23.5%) early complications after arthroplasty. Univariable logistic regression analysis found that preoperative body mass index (BMI p= 0.031), C-reactive protein (CRP p= 0.017) and serum Albumin (p= 0.006) were potential risk factors for early complications. Then preoperative BMI, CRP and serum Albumin were stratified and used for multivariable logistic regression analysis The multivariate logistic regression analysis showed that preoperative higher BMI (⩾ 28 kg/m2; OR 10.440; 95% CI 2.674-41.170; p= 0.001) and lower serum Albumin (⩽ 35 g/L; OR 3.933; 95% CI 1.509-10.800; p= 0.006) were independent risk factors for early complications after arthroplasty in geriatric femoral neck fractures. However, preoperative higher CRP levels (> 10 mg/L; OR 1.139; 95% CI 1034-1428; p= 0.833) was found to be not an independent risk factor for early complications.CONCLUSION:Our results demonstrate that obesity and hypoalbuminemia are independent predictors for early complications during hospital stay after arthroplasty, which should be meticulously noted to minimize these risk factors in geriatric femoral neck fractures.

Objective Three-dimensionally (3D) printed patient-specific instrumentation (PSI) might help in this regard with individual design and more accurate osteotomy, but whether the utility of such instrumentations minimizes the variability of patellar height in total knee arthroplasty (TKA) and the reasons for this effect are unknown. Our aim is to compare and analyze the variability of patellar height with PSI and conventional instrumentation (CI) in TKA. Methods Between March 2018 and November 2021, 215 patients with severe knee osteoarthritis who were treated with primary unilateral TKA were identified for this observational study. The patients were divided into the CI-TKA group and PSI-TKA group according to the osteotomy tools used in TKA. Preoperative and postoperative radiographic parameters including hip–knee–ankle angle (HKA), posterior tibial slope (PTS), Insall–Salvati ratio, modified Caton–Deschamps (mCD) ratio, anterior condylar offset (ACO), and posterior condylar offset (PCO) were evaluated. Results The groups were similar in patients' demographic data, clinical scores, and radiographic parameters preoperatively. Overall, according to the results of the Insall–Salvati ratio, postoperative patellar height reduction was noted in 140 patients (65.1%). Interestingly, the variability of patellar height was smaller in the PSI-TKA group. Radiographic evaluation revealed that the Insall–Salvati ratio after TKA had a minor change in the PSI-TKA group ( p = 0.005). Similarly, the mCD ratio after TKA also had a minor change in the PSI-TKA group ( p < 0.001). Compared to those in the CI-TKA group, the ACO ( p < 0.001) and PCO ( p = 0.011) after TKA had a minor change in the PSI-TKA group, but no minor PTS change ( p = 0.951) was achieved in the PSI-TKA group after TKA. However, even with 3D-printed patient-specific instrumentation, there were still significant reductions in patellar height, ACO, PCO, and PTS after TKA ( p < 0.001). Conclusion The variability of patellar height was sufficiently minimized with more accurate anterior and posterior femoral condyle osteotomy when 3D printed PSI was used. Furthermore, there was a trend in over-resection of the femoral anterior and posterior condyle and a marked reduction in PTS during TKA, which could lead to a change in patellar height and might result in more patellofemoral complications following TKA. Level of evidence Level II.

Objective To find out the causes of anterior femoral notching in 3D printed patient-specific patient-specific instrumentation (PSI) assisted total knee arthroplasty (TKA). Methods A retrospective analysis was carried out on the consecutive cases undergoing PSI assisted TKA in the Peking University International Hospital from January 2019 to September 2021. The clinical data of those having anterior femoral notching were collected. 3D CT scanning was performed on the knee joint after intraoperative osteotomy and the intraoperative bone fragments. Rapidform software (Version 2006) was used to reconstruct 3D images and to perform image registration and comparison analysis with the preoperatively planned 3D models. The anterior femoral notching depth was measured, and the differences in the thickness of bone fragments between preoperatively planned and intraoperative bone cutting in order to analyze the causes of the anterior femoral notching. Results A total of 86 consecutive cases (94 knees) were included and 17 cases (18/94, 19.1%) of them had anterior femoral notching. The causes of anterior femoral notching were summarized into 3 categories: abnormal position of the PSI (10 cases, 83.3%), intraoperative reduction of the femoral prosthesis size (2 cases, 16.7%), and overextension of the femoral prosthesis (1 case, 8.3%). Conclusion Abnormal femoral PSI position, intraoperative reduction of femoral prosthesis size, and preoperative femoral prosthesis overextension design are the main causes of anterior femoral notching after PSI assisted knee arthroplasty.

Objective To explore the prediction accuracy of prosthesis size of the modified 3D printed patient-specific instrumentation (PSI)-assisted total knee arthroplasty (TKA) by comparing the difference between intraoperative prosthesis size and preoperative planned prosthesis size. Methods We optimized and improved the workflow, design scheme, shape of guide, operation technology and verification method of the traditional PSI-assisted TKA. A total of 126 patients (137 knees) who received 3D printed PSI-assisted TKA based on preoperative CT images in our center were recruited in this study. The differences between the actual prosthesis size and the preoperative planned size were compared and analyzed. Results All patients completed the surgery successfully, and no serious complications occurred. For the femoral side, the difference between the actual used size and the doctor's planned size was observed in 7 cases, and the difference between the actual used size and the engineer's planned size was in 25 cases (P < 0.01), and the engineer's planned size adjusted by doctors was 19 cases (P < 0.01). For the tibial side, the actual used size and the doctor's planned size was 39 cases, the difference between the actual used size and the engineer's planned size was 44 cases, and the engineer's planned size adjusted by doctors was 5 cases. Conclusion The planned prosthesis size in Our modified 3D printed PSI-assisted TKA is consistent with the intraoperative prosthesis size, and the plan will be more consistent after adjustment by the doctors. [Key words]Objective To explore the prediction accuracy of prosthesis size of the modified 3D printed patient-specific instrumentation (PSI)-assisted total knee arthroplasty (TKA) by comparing the difference between intraoperative prosthesis size and preoperative planned prosthesis size. Methods We optimized and improved the workflow, design scheme, shape of guide, operation technology and verification method of the traditional PSI-assisted TKA. A total of 126 patients (137 knees) who received 3D printed PSI-assisted TKA based on preoperative CT images in our center were recruited in this study. The differences between the actual prosthesis size and the preoperative planned size were compared and analyzed. Results All patients completed the surgery successfully, and no serious complications occurred. For the femoral side, the difference between the actual used size and the doctor's planned size was observed in 7 cases, and the difference between the actual used size and the engineer's planned size was in 25 cases (P < 0.01), and the engineer's planned size adjusted by doctors was 19 cases (P < 0.01). For the tibial side, the actual used size and the doctor's planned size was 39 cases, the difference between the actual used size and the engineer's planned size was 44 cases, and the engineer's planned size adjusted by doctors was 5 cases. Conclusion The planned prosthesis size in Our modified 3D printed PSI-assisted TKA is consistent with the intraoperative prosthesis size, and the plan will be more consistent after adjustment by the doctors.

Objective To compare the effect of 3D printed patient-specific instrumentation (PSI) and conventional instrumentation (CI) on the patellar height and joint line position in total knee arthroplasty (TKA). Methods A retrospective case-control study was carried out on 58 patients, who underwent primary TKA in our hospital from January 2021 to October 2021. According to the osteotomy tools selected in TKA, the patients were divided into CI-TKA group and PSI-TKA group. The Insall-Salvati index, modified Caton-Deschamps (mCD) index and relative height of joint line before and after TKA were recorded and compared between the 2 groups. Results In terms of the Insall-Salvati index, the absolute difference between preoperative and postoperative score was 0.11 (0.07, 0.15) in the CI-TKA group, and 0.06 (0.03, 0.12) in the PSI-TKA group, and statistical difference was seen in the postoperative index between the 2 groups (P < 0.05). Similarly, the absolute difference between preoperative and postoperative mCD index was 0.16±0.09 in the CI-TKA group and 0.08±0.05 in the PSI-TKA group, and obvious difference was also seen in the postoperative difference between them (P < 0.01). However, the absolute difference between preoperative and postoperative joint line height was 2.53 (1.64, 4.40) mm in the CI-TKA group and 2.27 (1.53, 5.32) mm in the PSI-TKA group. There was no notable difference in postoperative joint line position between the 2 groups, but the position after TKA were significantly higher in both groups than that before TKA (P < 0.05). Conclusion The use of 3D printed PSI can help reduce the impact of TKA on the patella height, but there is no obvious advantage in maintaining the joint line position compared with conventional instrumentation.

[目的]介绍三维术前规划在全髋关节置换术(total hip arthroplasty,THA)中的应用方法和临床效果.[方法]2019年5月—2020年6月采用三维术前规划辅助人工全髋关节置换术8例.术前行双髋关节三维CT薄层扫描,建立三维立体模型,三维图像上确定解剖标志点,分析原始解剖形态及病理改变,实施模拟手术操作和假体置入.根据术前规划实施真实THA.[结果]术后髋臼杯外展角(41.63±4.63)°、前倾角(19.13±5.57)°;术后股骨前倾角(14.38±6.35)°;肢体长度改变为(-0.40±1.06)mm.三维术前规划髋臼侧假体型号6例与术前规划相同,1例相差1号,1例相差2号;股骨侧假体型号3例同术前规划,3例相差1号,2例相差2号.[结论]三维术前规划可以较精准的预估假体型号、安放假体位置..