Patients with simultaneous ruptures of the patellar tendon (PT) and anterior cruciate ligament (ACL) underwent PT repair and ACL reconstruction in a single or staged surgery. However, due to the limited cases, the design of previous studies was mostly case report with varying conclusions regarding recommended surgical strategy selection, the optimal surgical strategy remains a subject of debate. We conducted a retrospective case series and literature review, including 10 cases from local institution and 27 cases from 17 studies. Demographic information, injury causes, surgical strategies, combined injuries, whether to return to (pre-injury level) sports, postoperative complications, Lysholm score and International Knee Documentation Committee (IKDC) score were identified retrospectively or reviewed from previous studies. The Fisher's exact test was used to compare the incidence of postoperative complications between different surgical strategy groups, and linear logistic regression was used to analyze factors influencing postoperative knee function scores. Of the 37 patients, 15 patients (40.5%) underwent single surgery and 22 patients (59.5%) underwent staged surgery. Postoperative complications occurred in 5 (33.3%) patients after single surgery and in none after staged surgery, with the former being significantly more frequent than the latter (P = 0.007). Linear regression of postoperative knee function scores showed that surgical strategy did not significantly affect postoperative Lysholm and IKDC scores (P = 0.327 and P = 0.348, respectively). This study demonstrates that staged surgery significantly reduces postoperative complications compared to single surgery in patients with simultaneous PT and ACL ruptures and should be considered the preferred approach, especially when an expedited return to sports is not a priority.
Background: The clinical interpretation of patient-reported outcome measures (PROMs) after anterior cruciate ligament (ACL) reconstruction (ACLR) can be challenging. This study aimed to establish the clinical relevance of PROMs by determining maximal outcome improvement (MOI) thresholds at mid-term follow-up after primary ACLR. Methods: A total of 343 patients who underwent primary single-bundle ACLR using hamstring tendon autograft at our institute were included. Patients were queried with a 2-option anchor question regarding satisfaction with their current knee symptom state. The MOI of a PROM was calculated for each patient as the percentage of improvement normalized by the maximal possible improvement. The MOI threshold for each PROM was determined as the optimal cutoff value for predicting patient satisfaction based on receiver operating characteristic curve analysis. Multivariable logistic regression analyses were performed to identify predictors of achieving these thresholds. Subgroup analyses that stratified the time from injury to surgery within the cohort were performed, and MOI thresholds were recalculated within each of these subgroups. The PROMs evaluated in this study were the modified Lysholm Knee Score and the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC) score. Results: The calculated MOI threshold was 35.1% for the Lysholm score and 46.7% for the IKDC score. A longer time from injury to surgery reduced the odds of achieving the MOI threshold for the Lysholm score (odds ratio [OR] per time bracket = 0.7114, p < 0.0001) and IKDC score (OR = 0.8038, p = 0.0003). Male sex was associated with higher odds of achieving the MOI threshold for the IKDC score (OR = 1.9645, p = 0.0143). For patients with chronicity of ≤6 months, the MOI threshold was 35.1% for the Lysholm score and 57.9% for the IKDC score, and for patients with chronicity of >6 months, the thresholds were 24.5% and 27.1%, respectively. Conclusions: The calculated MOI thresholds for the Lysholm and IKDC scores at mid-term follow-up after primary ACLR were 35.1% and 46.7%, respectively. Greater chronicity of the ACL injury was associated with lower odds of achieving the MOI thresholds for the PROMs at mid-term follow-up. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.
Objectives: To study the design of nonmetallic crowns for deciduous molars by means of computer aided design and to analyze the key parameters of the nonmetallic crowns of deciduous molars using finite element method. Methods: The three-dimensional model of a mandibular second primary molar was constructed by using a micro-CT system. The thickness of the crown was limited to 0.5 mm and four different crown shapes (chamfer+anatomic, chamfer+non-anatomic, knife edge+anatomic and knife edge+non-anatomic) were designed. Then, the crown shape was limited as chamfer+non-anatomic and five different thicknesses of the crown (0.50, 0.75, 1.00, 1.25, 1.50 mm) were designed, and three different materials, including polyetherketoneketone (PEKK), polymethylmethacrylate (PMMA) resin and resin-infiltrated ceramic, were applied to make the crown. Stress distribution and fatigue of each component of the model under vertical and oblique loadings were analyzed by using finite element method. Non-axial retention analysis was performed on chamfer+non-anatomic crowns, made of PMMA resin, with thicknesses of 0.50, 0.75, 1.00, 1.25 and 1.50 mm. Results: Among the four crown shape designs, the chamfer+non-anatomic type crown showed the lowest von Mises stress and the highest safety factor. By comparing three different materials, the resin-infiltrated ceramic group showed obvious stress concentration on the buccal edge of the crown and the PEKK group showed stress concentration in the adhesive layer. Results of non-axial retention analysis showed that the torques required by the crowns with five thicknesses at the same rotation angle were as follows: 4 856.1, 4 038.1, 3 497.3, 3 256.3 and 3 074.3 N⋅m, respectively. The comparison of areas of the adhesives fracture among groups were as follows: 0.5 mm group < 0.75 mm group < 1.00 mm group < 1.25 mm group < 1.50 mm group. Conclusions: In the design of nonmetallic crowns for primary molars, the edge of the crown should be designed as chamfer, the shape of the inner crown should be non-anatomical and the minimum preparation amount of the occlusal surface should be 1.00 mm. Among the three materials, PMMA resin, of which elastic modulus is similar to the dentin and the dental adhesive, might be the most suitable material for the crowns of primary molars.目的： 通过有限元法探索乳磨牙非金属冠制作的关键参数，为乳磨牙非金属冠的临床应用提供参考。 方法： 构建下颌第二乳磨牙三维模型；限定牙冠厚度为0.5 mm，设计无角肩台解剖式、无角肩台非解剖式、刃状边缘解剖式、刃状边缘非解剖式4种牙冠形态；对无角肩台非解剖式牙冠设计0.50、0.75、1.00、1.25、1.50 mm 5种牙冠厚度，对牙冠分别赋予聚醚酮酮（polyetherketoneketone，PEKK）（PEKK组）、聚甲基丙烯酸甲酯（polymethylmethacrylate，PMMA）树脂（PMMA组）和树脂浸润陶瓷（树脂浸润陶瓷组）3种不同材料，模拟垂直及倾斜加载，对模型各组件进行应力及疲劳分析；将上述0.50、0.75、1.00、1.25、1.50 mm 5种厚度的无角肩台非解剖式牙冠的材料赋予为PMMA树脂，模拟牙冠旋转脱位，对不同厚度的无角肩台非解剖式牙冠进行非轴向固位分析。 结果： 构建下颌第二乳磨牙有限元模型后，静力及疲劳分析显示无角肩台非解剖式牙冠及粘接剂层的von Mises应力峰值最小，安全系数最高。对比不同材料，树脂浸润陶瓷组在牙冠颊侧边缘出现明显的应力集中，PEKK组粘接剂层出现应力集中。非轴向固位分析显示0.50、0.75、1.00、1.25、1.50 mm 5种厚度的牙冠在转动相同角度时需要的扭矩大小分别为4 856.1、4 038.1、3 497.3、3 256.3及3 074.3 N⋅m，各组粘接剂断裂面积大小：0.50 mm组<0.75 mm组<1.00 mm组<1.25 mm组<1.50 mm组。 结论： 乳磨牙非金属冠的设计中，冠的边缘设计建议为无角肩台，内冠形态为非解剖式，（牙合）面最小预备量为1.00 mm，制作材料建议采用与牙本质及粘接剂弹性模量接近且各项测评性能较稳定的PMMA树脂材料。.
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