BACKGROUND: The infrapatellar fat pad (IPFP) lies extrasynovial and intracapsular, preserving the joint cavity and serving as a biochemical regulator of inflammatory reactions. However, there is a lack of research on the relationship between anterior knee pain (AKP) and the IPFP after medial patellofemoral ligament reconstruction (MPFLR). Pinpointing the source of pain enables clinicians to promptly manage and intervene, facilitating personalized rehabilitation and improving patient prognosis.
METHODS: A total of 181 patients were included in the study. These patients were divided into the AKP group (n = 37) and the control group (n = 144). Clinical outcomes included three pain-related scores, Tegner activity score, patient satisfaction, etc. Imaging outcomes included the IPFP thickness, IPFP fibrosis, and the IPFP thickness change and preservation ratio. Multivariate analysis was used to determine the independent factors associated with AKP. Finally, the correlation between independent factors and three pain-related scores was analyzed to verify the results.
RESULTS: The control group had better postoperative pain-related scores and Tegner activity score than the AKP group (P < 0.01). The AKP group had lower IPFP thickness change ratio and preservation ratio (P < 0.001), and smaller IPFP thickness (P < 0.05). The multivariate analysis revealed that the IPFP thickness change ratio [OR = 0.895, P < 0.001] and the IPFP preservation ratio [OR = 0.389, P < 0.001] were independent factors related to AKP, with a significant correlation between these factors and pain-related scores [|r| > 0.50, P < 0.01].
CONCLUSIONS: This study showed the lower IPFP change ratio and preservation ratio may be independent factors associated with AKP after MPFLR. Early detection and targeted intervention of the underlying pain sources can pave the way for tailored rehabilitation programs and improved surgical outcomes. LEVEL OF EVIDENCE LEVEL III.

UNASSIGNED: To compare the effectiveness of intramedullary nailing fixation via suprapatellar approach and medial parapatellar approach in semi-extended position in the treatment of multiple tibial fractures.
UNASSIGNED: The clinical data of 43 patients with multiple tibial fractures treated with intramedullary nailing fixation between July 2018 and December 2022 were retrospectively analyzed, including 23 patients treated with suprapatellar approach in semi-extended position (group A) and 20 patients with medial parapatellar approach in semi-extended position (group B). There was no significant difference in gender, age, cause of injury, time from injury to operation, AO/Orthopaedic Trauma Association (AO/OTA) classification, preoperative visual analogue scale (VAS) score, and range of motion (ROM) of the knee joint between the two groups ( P>0.05). The operation time, intraoperative blood loss, incision length, intraoperative fluoroscopy frequency, and fracture healing time were recorded and compared. The VAS score and ROM of the knee joint were analyzed at 4, 8, and 12 weeks after operation, and the incidence of postoperative complications was observed; knee function was evaluated by Lysholm score at last follow-up.
UNASSIGNED: The operations were successfully completed in both groups, and there was no complication such as nerve and blood vessel injury during operation, and all incisions healed by first intention. There was no significant difference in operation time, intraoperative blood loss, and intraoperative fluoroscopy frequency between the two groups ( P>0.05), but the incision length in group B was significantly longer than that in group A ( P<0.05). Patients in both groups were followed up 12-30 months, with an average of 21.1 months. The VAS score decreased and ROM increased gradually in both groups with time after operation, showing significant differences between different time points ( P<0.05). The VAS score of group B was significantly lower than that of group A at 4 and 8 weeks after operation ( P<0.05); there was no significant difference in VAS score and ROM between the two groups at other time points ( P>0.05). There was no significant difference in fracture healing time between the two groups ( P>0.05). During the follow-up, there was no complication such as internal fixator loosening, breakage, and loss of fracture reduction. At last follow-up, the Lysholm score in group B was significantly better than that in group A ( P<0.05).
UNASSIGNED: Both the suprapatellar approach and the medial parapatellar approach in semi-extended position can achieve satisfactory results in the treatment of multiple tibial fractures. The medial parapatellar approach has lower symptoms of early knee pain and better long-term function.
UNASSIGNED: 比较膝关节半伸直位髌上入路与髌旁内侧入路髓内钉固定治疗胫骨多段骨折的临床疗效。.
UNASSIGNED: 回顾分析2018年7月—2022年12月收治且符合选择标准的43例采用髓内钉固定治疗的胫骨多段骨折患者临床资料，其中23例采用膝关节半伸直位髌上入路（A组），20例采用膝关节半伸直位髌旁内侧入路（B组）。两组患者性别、年龄、致伤原因、受伤至手术时间、骨折国际内固定研究协会/美国骨创伤协会（AO/OTA）分型及术前疼痛视觉模拟评分（VAS）、膝关节活动度（range of motion，ROM）等基线资料比较差异均无统计学意义（ P>0.05）。记录并比较两组患者手术时间、术中失血量、切口长度、术中透视次数及骨折愈合时间，统计两组术后4、8、12周膝关节VAS评分及ROM，观察术后并发症发生情况；末次随访时采用Lysholm 评分评价膝关节功能。.
UNASSIGNED: 两组患者均顺利完成手术，术中无神经、血管损伤等并发症发生，术后所有切口均Ⅰ期愈合。两组手术时间、术中失血量、术中透视次数比较差异均无统计学意义（ P>0.05）；但B组手术切口长于A组，差异有统计学意义（ P<0.05）。两组患者均获随访，随访时间12～30个月，平均21.1个月。术后随时间延长，两组膝关节VAS评分均逐渐降低，ROM逐渐增加，各时间点间差异均有统计学意义（ P<0.05）；术后4、8周B组VAS评分低于A组，差异有统计学意义（ P<0.05），其余时间点两组间比较膝关节VAS评分及ROM差异均无统计学意义（ P>0.05）。两组骨折均愈合，愈合时间比较差异无统计学意义（ P>0.05）。随访期间无内固定物松动、断裂及骨折复位丢失等并发症发生。末次随访时，B组膝关节Lysholm评分显著优于A组，差异有统计学意义（ P<0.05）。.
UNASSIGNED: 膝关节半伸直位髌上入路与髌旁内侧入路髓内钉固定治疗胫骨多段骨折均可获得满意疗效，髌旁内侧入路术后早期膝关节疼痛症状更轻，远期膝关节功能更优。.

UNASSIGNED: Patellar cartilage lesions are a frequent and challenging finding in orthopaedic clinical practice. This study aimed to evaluate a chitosan-based scaffold\'s mid-term clinical and imaging results patients with patellar cartilage lesions.
UNASSIGNED: Thirteen patients (nine men, four women, 31.3 ± 12.7 years old) were clinically evaluated prospectively at baseline, 12, 24 and at a final minimum follow-up of 60 months (80.2 ± 14.7) with International Knee Documentation Committee (IKDC) subjective, Knee Injury and Osteoarthritis Outcome Score and Tegner scores. A magnetic resonance analysis was performed at the last follow-up using the Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) 2.0 score.
UNASSIGNED: An overall significant clinical improvement in the scores was observed from baseline to all follow-ups, with stable clinical results from 24 months to the mid-term evaluation. The IKDC subjective score passed from 46.3 ± 20.0 at baseline to 70.1 ± 21.5 at the last follow-up (p = 0.029). Symptoms\' duration before surgery negatively correlated with the clinical improvement from baseline to the final follow-up (p = 0.013) and sex influenced the improvement of activity level from the preoperative evaluation to the final follow-up, with better results in men (p = 0.049). In line with the clinical findings, positive results were documented in terms of cartilage repair quality with a mean MOCART 2.0 score of 72.4 ± 12.5.
UNASSIGNED: Overall, the use of this chitosan-based scaffold provided satisfactory results with a stable clinical improvement up to mid-term follow-up, which should be confirmed by further high-level studies to be considered a suitable surgical option to treat patients affected by patellar cartilage lesions.
UNASSIGNED: Level IV, prospective case series.

UNASSIGNED: Medial patellar facet lesions have been well-described in the setting of patellar instability. However, relatively little is known about risk factors for atraumatic medial patellar facet lesions.
UNASSIGNED: To identify clinical and radiographic risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability. It was hypothesized that a posterior tibial tubercle relative to the trochlear groove would be a risk factor for atraumatic medial patellar facet lesions.
UNASSIGNED: Case-control study; Level of evidence, 3.
UNASSIGNED: A total of 37 patients with atraumatic medial patellar facet lesions were matched by age, sex, and body mass index with 37 control patients without a history of patellofemoral dysplasia. Demographic and imaging characteristics were compared between groups. Plain radiography was used to evaluate Wiberg type, and magnetic resonance imaging was used to calculate Caton-Deschamps index, tibial tubercle-trochlear groove distance, trochlear facet asymmetry ratio, patellotrochlear index, sulcus depth, patellar bisect ratio, and tibial tubercle height. Statistically significant variables from univariate analysis were used as inputs to the multivariate regression model to assess independent risk factors.
UNASSIGNED: There were no differences between groups with respect to Wiberg type, Caton-Deschamps index, tibial tubercle-trochlear groove distance, sulcus depth, or patellotrochlear index (P > .05 for all). The medial facet lesion group had a larger medial trochlear facet (trochlear facet asymmetry ratio, 0.72 ± 0.11 vs 0.60 ± 0.09; P < .001), a more medial-lying patella in the trochlear groove (patellar bisect ratio, 0.57 ± 0.06 vs 0.55 ± 0.07; P = .035), and a more posterior tibial tubercle relative to the trochlear groove (tibial tubercle height, -3.13 ± 5.21 vs -0.23 ± 5.93 mm; P = .030) compared with the control group. Multivariate regression analysis identified trochlear facet asymmetry and tibial tubercle height as independent risk factors for medial patellar facet lesions (relative risk = 97.3 [95% CI, 14.9-635.1], P < .001 and relative risk = 0.95 [95% CI, 0.92-0.98], P = .004, respectively).
UNASSIGNED: A relatively larger medial trochlear facet and a more posterior tibial tubercle relative to the trochlear groove were found to be risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability.

BACKGROUND: The patella, or kneecap, is a sesamoid bone situated deep to the fascia latae and the tendinous fibers of the rectus femoris. The medial and lateral facets of the patella articulate with the medial and lateral condyles of the femur, respectively, to form the patellofemoral component of the knee joint. When joint cartilage is destroyed due to osteoarthritis, inflammatory arthritis, post-traumatic degenerative joint disease, or osteonecrosis/joint collapse with cartilage loss, a surgical treatment called knee arthroplasty, or total knee arthroplasty (TKA), is used to rebuild the knee joint.
OBJECTIVE: The purpose of our study is to provide a detailed morphometric analysis of the human patella.
METHODS: A total of 168 patellae (86 left, 82 right) were examined. Eleven parameters were determined to evaluate patella morphometry, and the bones were also evaluated with the Wiberg classification.
RESULTS: Type I patella was observed in 13 samples (7.74%); 109 (64.88%) and 46 (27.38%) were Type II and Type III, respectively. In the statistical analysis, significant differences were found between the right and left patellae in terms of patellar thickness, vertical ridge length, and Wiberg angle (p<0.05). There were also significant differences between the Wiberg types and the medial articular width and lateral articular width (p<0.05).
CONCLUSIONS: In order to avoid potential difficulties during knee surgery, it is crucial to understand the typical morphological and morphometric properties of the patella. We believe that this study will be useful to surgeons who perform surgical approaches to the knee and to clinicians who evaluate the diseases of the region.

UNASSIGNED: Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown.
UNASSIGNED: To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes.
UNASSIGNED: Case series; Level of evidence, 4.
UNASSIGNED: In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed.
UNASSIGNED: The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts (P = .69). For autografts, 6 of 17 (35.3%) failures occurred with gracilis, but 0 of 13 (0%) occurred with semitendinosus (P = .02). Compared with patients without failures, patients with failed primary MPFLR were significantly younger (P = .0005) and were able to touch the palm to the floor with their knees extended (P = .03). For radiographic parameters, the patellar height and tilt were significantly higher in the failure group. The postoperative PROs were suboptimal at a mean follow-up of 5.2 years. All but 1 patient were satisfied with the final outcome.
UNASSIGNED: At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.

UNASSIGNED: The purpose of this study is to assess clinical and functional outcomes in separate cohorts of operatively and nonoperatively managed pediatric patella fractures.
UNASSIGNED: A retrospective review was completed for patients aged 5-19 years treated for a unilateral patella fracture at a single pediatric level-1 trauma center. Patients were excluded for osteochondral fracture associated with patellar dislocation, polytrauma presentation with additional fractures, or <3 months of clinical follow-up. Functional outcomes were assessed via the Pediatric International Knee Documentation Committee form and the Marx Knee Activity Scale.
UNASSIGNED: A total of 53 patients met inclusion criteria; 30 patients were treated operatively and 23 patients were treated nonoperatively. Patients with patellar sleeve/pole fractures were significantly younger by 5.2 years (p < 0.01) and presented with greater variability in mechanism of injury (p < 0.01). The nonoperative cohort achieved bony healing and returned to sports at a median (interquartile range) of 1.7 (1.2-2.3) months and 2.8 (2.3-3.3) months, respectively, post-injury. The operative group achieved bony healing and returned to sports at 2.8 (2.1-3.5) months and 5.9 (4.0-7.1) months, respectively, following surgery. Median (interquartile range) Pediatric International Knee Documentation Committee and Marx scores were 98 (89-100) and 14 (10-16), respectively, for the nonoperative group, and 92 (84-99) and 13 (12-16), respectively, for the operative group. No significant differences in patient-reported outcomes were observed between fracture patterns or treatment cohorts.
UNASSIGNED: Pediatric and adolescent patients sustaining patella fractures reported long-term functional outcomes comparable to normative values, across multiple fracture patterns and with appropriate operative and nonoperative treatment. Fractures requiring surgery were expectedly associated with slower healing and return to sport timelines.
UNASSIGNED: Therapeutic Level III.

UNASSIGNED: Treatment of comminuted patellar fractures accompanied by coronal split articular and inferior pole fragments is a challenge. To treat this difficult fracture, we perform articular fragment detachment and separate fixation for coronal split articular and inferior pole fragments. We aimed to evaluate the radiological and clinical outcomes of our technique in comminuted patellar fractures at least 1 year after surgery.
UNASSIGNED: Between January 2019 and June 2022, 15 patients diagnosed with comminuted patellar fractures accompanied by coronal split articular and inferior pole fragments based on preoperative computed tomography underwent surgery using the articular detachment technique. The key point of this technique was anatomical reduction and subchondral fixation of the coronal split articular fragment to the superior main fragment after complete detachment of the coronal split fragment from the inferior pole. The remaining inferior pole was fixed using a separate construct. Postoperative articular gap, articular step-off, and complications, including resorption, reduction loss, and avascular necrosis of fixed articular fragments, were evaluated as radiological outcomes. Range of motion and the Lysholm scores were used to evaluate clinical outcomes.
UNASSIGNED: Among the 15 patients, the coronal split articular fragments were fixed using Kirschner wires in 13 patients and headless screws in 2 patients. The inferior poles were fixed using separate vertical wiring in 13 patients and tension-band wiring in 2 patients. A postoperative articular gap was noted in 7 patients, with an average articular gap of 1.0 mm (range, 0.7-1.6 mm). No articular step-off was observed. Bone union and normal range of motion were achieved in all patients. On the 1-year postoperative lateral radiograph, resorption of the articular fracture site was seen in 5 patients. There was no loss of reduction or avascular necrosis of the coronal split articular fragments. The average postoperative Lysholm score at 1 year was 89.3 ± 4.1 (range, 82-95).
UNASSIGNED: The technique would be a reliable and safe option for the surgical treatment of comminuted patellar fractures accompanied by coronal split articular and inferior pole fragments in terms of anatomical reduction and stable fixation of articular fragments without risk of avascular necrosis.

BACKGROUND: The patellar height index is important; however, the measurement procedures are time-consuming and prone to significant variability among and within observers. We developed a deep learning-based automatic measurement system for the patellar height and evaluated its performance and generalization ability to accurately measure the patellar height index.
METHODS: We developed a dataset containing 3,923 lateral knee X-ray images. Notably, all X-ray images were from three tertiary level A hospitals, and 2,341 cases were included in the analysis after screening. By manually labeling key points, the model was trained using the residual network (ResNet) and high-resolution network (HRNet) for human pose estimation architectures to measure the patellar height index. Various data enhancement techniques were used to enhance the robustness of the model. The root mean square error (RMSE), object keypoint similarity (OKS), and percentage of correct keypoint (PCK) metrics were used to evaluate the training results. In addition, we used the intraclass correlation coefficient (ICC) to assess the consistency between manual and automatic measurements.
RESULTS: The HRNet model performed excellently in keypoint detection tasks by comparing different deep learning models. Furthermore, the pose_hrnet_w48 model was particularly outstanding in the RMSE, OKS, and PCK metrics, and the Insall-Salvati index (ISI) automatically calculated by this model was also highly consistent with the manual measurements (intraclass correlation coefficient [ICC], 0.809-0.885). This evidence demonstrates the accuracy and generalizability of this deep learning system in practical applications.
CONCLUSIONS: We successfully developed a deep learning-based automatic measurement system for the patellar height. The system demonstrated accuracy comparable to that of experienced radiologists and a strong generalizability across different datasets. It provides an essential tool for assessing and treating knee diseases early and monitoring and rehabilitation after knee surgery. Due to the potential bias in the selection of datasets in this study, different datasets should be examined in the future to optimize the model so that it can be reliably applied in clinical practice.
BACKGROUND: The study was registered at the Medical Research Registration and Filing Information System (medicalresearch.org.cn) MR-61-23-013065. Date of registration: May 04, 2023 (retrospectively registered).

Experimental validation of computational simulations is important because it provides empirical evidence to verify the accuracy and reliability of the simulated results. This validation ensures that the simulation accurately represents real-world phenomena, increasing confidence in the model\'s predictive capabilities and its applicability to practical scenarios. The use of musculoskeletal models in orthopedic surgery allows for objective prediction of postoperative function and optimization of results for each patient. To ensure that simulations are trustworthy and can be used for predictive purposes, comparing simulation results with experimental data is crucial. Although progress has been made in obtaining 3D bone geometry and estimating contact forces, validation of these predictions has been limited due to the lack of direct in vivo measurements and the economic and ethical constraints associated with available alternatives. In this study, an existing commercial surgical training station was transformed into a sensorized test bench to replicate a knee subject to a total knee replacement. The original knee inserts of the training station were replaced with personalized 3D-printed bones incorporating their corresponding implants, and multiple sensors with their respective supports were added. The recorded movement of the patella was used in combination with the forces recorded by the pressure sensor and the load cells, to validate the results obtained from the simulation, which was performed by means of a multibody dynamics formulation implemented in a custom-developed library. The utilization of 3D-printed models and sensors facilitated cost-effective and replicable experimental validation of computational simulations, thereby advancing orthopedic surgery while circumventing ethical concerns.