Synovial hemangioma presenting with chronic painful infrapatellar mass: a case report.

BACKGROUND: Synovial hemangiomas are rare benign vascular anomalies surrounded by a synovial lining and were first described by Bouchut in 1856. These neoplasms can develop in the intra-articular region, resulting in effusions and knee pain. However, their cause remains unknown. Prompt diagnosis and intervention are critical to prevent chondral damage. Histopathological examination is used to achieve the diagnosis, which is often delayed because of a lack of specific clinical signs. This report describes a unique case in which a painful infrapatellar mass was diagnosed as a synovial hemangioma. The absence of typical magnetic resonance imaging (MRI) findings highlights the importance of arthroscopic excision for diagnosis and symptom relief. CASE PRESENTATION: A 20-year-old woman presented with persistent anterior left knee pain that became exacerbated when she climbed stairs. Despite previous pain management and physical therapy, she developed a painful lump beneath her patella that worsened over time. She had also undergone arthrocentesis, but this did not relieve her pain. Physical examination revealed a palpable, immobile 5-cm mass along the patellar tendon with limited knee flexion and extension and normal ligament stability. T1-weighted fat-saturated MRI of the left knee with gadolinium-based contrast revealed a lobulated intra-articular mass in Hoffa's fat pad that resembled a soft tissue chondroma. A biopsy of the mass was performed to provide histopathological evidence, confirming the benign nature of the mass. The subsequent excisional arthroscopy, combined with incision enlargement for mass removal, confirmed the histopathologic diagnosis of synovial hemangioma based on the presence of numerous dilated blood vessels and venous proliferation within sections of the synovium. Recovery was complete, and no residual tumor was detected on follow-up MRI after 1 year. CONCLUSION: This case study emphasizes the importance of arthroscopic excision over open surgery for patients with synovial hemangioma. The minimally invasive nature of arthroscopy combined with the well-encapsulated nature and location of the mass facilitates complete resection.

Trochlea Dysplasia as the Major Anatomic Risk Factors for Patellofemoral Joint Instability: An Infographic as a Visual Learning Tool.

Patellofemoral instability (PFI) is a common condition in children and adolescents, ranging from mild discomfort and mal-tracking to lateral patellar dislocation [1]. A number of anatomical risk factors have been described in the literature, such as trochlear dysplasia, patella alta, excessive tibial tuberosity to trochlear groove (TT-TG) distance, patellar tilt and soft tissue alterations [2]. Among them, TD has been identified as the main anatomical risk factor with the strongest association with PFI [1, 2]. In the study by Dejour et al. [2] radiographically observed TD was identified in 96% of patients with a history of patellofemoral dislocation [1, 2]. Patients with Dejour Type D dysplasia are characterized by a prominent and convex lateral facet with a vertical connection to a hypoplastic medial facet (Figure 1), which provides inadequate tracking of the patella in the trochlea during flexion leading to patella subluxation [2]. Non-operative treatment of lateral patellar dislocation presents a rate of re-dislocation up to 70% within 24 months of the first episode [3]. Sulcus deepening trochleoplasty is indicated for Type B and D dysplasia, in order to improve patella tracking, reduce the rate of re-dislocation and achieve good functional outcomes [2, 4]. Trochlea dysplasia is defined as a shallow or flattened groove with decreased resistance to lateral patellar translation. TD can be assessed on computed tomography (CT) and magnetic resonance imaging (MRI) with the use of overlapping axial images and are able to show perfectly the global shape of the femoral trochlea [2]. The thresholds for identifying trochlear dysplasia are established based on the sulcus angle ≥ 145°, medial/lateral trochlea facet asymmetry < 40%, trochlear depth < 3 mm and lateral trochlear inclination ≤ 11° and therefore it can be used in young adolescents [4, 5]. A deep knowledge of anatomic variations and abnormalities of the patellofemoral joint, which may predispose to PFI, is crucial in order to choose the appropriate treatment for each patient.

Effect of patellofemoral joint overstuffing following total knee arthroplasty without patella resurfacing on clinical efficacy and related factors analysis.

OBJECTIVE: To analyze the influencing factors for patellofemoral joint (PFJ) overstuffing following total knee arthroplasty (TKA) without patella resurfacing, and explore the effect of PFJ overstuffing on clinical efficacy. METHODS: A retrospective analysis was conducted on 168 patients with end-stage knee osteoarthritis who underwent TKA without patella resurfacing at our hospital between Match 2019 and September 2021. The clinical data of these patients were retrospectively analyzed. In this study, PFJ overstuffing was defined as a postoperative PFJ distance greater than 1 mm compared to the preoperative measurement. The occurrence of postoperative PFJ overstuffing was counted. The patients were divided into the overstuffing group (n = 109) and the non-overstuffing group (n = 59) to count the patellar thickness and thickness of femoral anterior condyle in all patients before and after surgery, and analyze the influencing factors for postoperative PFJ overstuffing in such patients. Patients were followed up for 2 years to compare the recovery time of postoperative pain, score of visual analogue scale (VAS) and flexion activity between the two groups. RESULTS: There was no significant difference in patellar thickness between preoperative and postoperative measurements of the patients (P > 0.05). However, the thickness of the femoral anterior condyle and the PFJ distance after surgery increased significantly compared with those before surgery (P < 0.05). Among the 168 patients, 109 cases (64.88%) experienced PFJ overstuffing. The risk of PFJ overstuffing was higher in female patients than in male (P < 0.05). The preoperative thickness of the femoral anterior condyle in the overstuffing group was significantly smaller compared to the non-overstuffing group (P < 0.001). Compared with the non-overstuffing group, the overstuffing group had longer recovery time of postoperative pain (P < 0.05), and had lower flexion activity at 2 years after surgery (P < 0.001). However, no significant difference was found in VAS score between the overstuffing group and the non-overstuffing group at 2 years after surgery (P > 0.05). Spearman rank correlation analysis indicated females tend to have a lower preoperative thickness of the femoral anterior condyle (r=-0.424, P < 0.001), as well as a positive postoperative PFJ overstuffing (r = 0.237, P < 0.05). Furthermore, there was a negative correlation between preoperative thickness of the femoral anterior condyle and postoperative PFJ overstuffing (r=-0.540, P < 0.001). CONCLUSION: Following TKA without patella resurfacing, there is a high risk of PFJ overstuffing, particularly among female patients and those with a small thickness of the femoral anterior condyle. Therefore, special attention should be given to these high-risk groups during clinical treatment.

The thickness change ratio and preservation ratio of the infrapatellar fat pad are related to anterior knee pain in patients following medial patellofemoral ligament reconstruction.

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.

Deep learning-based automatic measurement system for patellar height: a multicenter retrospective study.

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. CONCLUSION: 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. TRIAL REGISTRATION: 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).

Supratubercle Anterior Closing Wedge Osteotomy: No Changes in Patellar Height and Significant Decreases in Anterior Tibial Translation at 6 Months Postoperatively.

BACKGROUND: Because of the increased prevalence of revision anterior cruciate ligament (ACL) reconstruction, there has been a desire to understand the role of posterior tibial slope on increased anterior tibial translation and increased ACL graft forces. One potential concern in supratubercle anterior closing wedge proximal tibial osteotomy (ACW-PTO) for decreasing the posterior tibial slope is the risk of altering the patellar height. PURPOSE: To radiographically assess changes in (1) patellar height, (2) anterior tibial translation, and (3) posterior tibial slope after supratubercle ACW-PTO. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who underwent supratubercle ACW-PTO by a single surgeon between July 2019 and June 2023 were included. Standardized lateral knee weightbearing radiographs to assess patellar height (via the Caton-Deschamps index), anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle, and posterior tibial slope were obtained at 4 time points (preoperatively and 1 day, 3 months, and 6 months postoperatively). Paired t test was used to compare differences between preoperative, 1-day, and 3- and 6-month values for patellar height as measured using the Caton-Deschamps index and for posterior tibial slope. Paired t test was also used to compare differences in the preoperative and 6-month postoperative values for anterior tibial translation. RESULTS: In 20 patients after ACW-PTO, the Caton-Deschamps index demonstrated a significant increase in patellar height on postoperative day 1 (P < .001) but no significant differences at 3 (P = .057) and 6 (P = .176) months postoperatively. Anterior tibial translation on standing lateral knee radiographs was significantly decreased by a mean of 8.9 mm from preoperatively to 6 months postoperatively (P < .001). Posterior tibial slope was significantly decreased by a mean of 11.2° from preoperatively to 6 months postoperatively (P < .001). CONCLUSION: Supratubercle ACW-PTO performed for ACL reconstruction failure in the setting of an increased posterior tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, after ACW-PTO, there was a significant decrease in anterior tibial translation and posterior tibial slope.

Evaluation of the relationship between the anatomical characteristics of the vastus medialis obliquus muscle and the patella chondral lesion occurrence.

OBJECTIVES: The study aims to investigate the relationship between the vastus medialis obliquus (VMO) muscle distal insertion features and patellar chondral lesion presence. PATIENTS AND METHODS: This cross-sectional study included a total of 100 patients (18 males, 82 females, mean age 67.2±7.1 years; range, 50 to 86 years) who underwent total knee arthroplasty (TKA). Radiological assessments, including merchant view and standing orthoroentgenograms, were conducted. The current osteoarthritis stage, varus angle, quadriceps angle (Q angle), patella-patellar tendon angle (P-PT angle), congruence angle, and sulcus angle were calculated. The VMO tendon length, muscle fiber angle, tendon insertion width measurements, and patellar chondral lesion localization data were obtained intraoperatively. Grouping was done according to the distal insertion width of the VMO tendon to the medial edge of the patella. The medial rim of the patella was divided into three equal-sized sectors. The first group (Group 1, n=31) consisted of patients who had an insertion from the quadriceps tendon into the upper one-third of the patella. The second group (Group 1, n=48) consisted of patients with a distal insertion expanding into the middle one-third of the patella. The third group (Group 3, n=21) consisted of patients who had a distal insertion extending into the distal third region of the medial patella margin. The patella joint surface was divided into sectors, and the presence and location of cartilage lesions were noted in detail. RESULTS: The mean tendon insertion width rate was 45.99±16.886% (range, 16.7 to 83.3%). The mean muscle fiber insertion angle was 51.85±11.67º (range, 20º to 80º). The mean tendon length was 12.45±3.289 (range, 4 to 20) mm. There was no significant difference between the mean age, weight, height, body mass index, BMI, fiber angle, tendon length, varus angle, Q angle, sulcus angle, and congruence angle data among the groups. In terms of the P-PT angle, Groups 1 and 2 had a significant relationship (p=0.008). No relationship was found between the mean fiber insertion angle, mean tendon length, or the presence of chondral lesions. There was a statistically significant difference among the groups regarding the presence of chondral lesions. The highest percentage of chondral lesion frequency was observed in Group 3 (95.24%), followed by Group 1 (90.3%) and Group 2 (89.6%), respectively. Compared to the other two groups, Group 3 had a higher average ratio of lesion areas per patient. CONCLUSION: Our study results demonstrate that the formation and localization of the patellar chondral lesions are affected by the insertion width type of the VMO muscle into the patella. Group 2-type insertion is associated with a lower lesion frequency rate than Groups 1 and 3.

A new and simple method for patellar height measurement: Fibula-condyle-patella angle.

OBJECTIVES: This study aims to evaluate the inter-observer reliability of fibula-condyle-patella angle measurements and to compare it with other measurement techniques. PATIENTS AND METHODS: Between January 01, 2023 and January 31, 2023, a total of 108 patients (20 males, 88 females; mean age: 47.5±12.0 years; range, 18 to 72 years) who underwent X-rays using the fibula-condyle-patella angle, Insall-Salvati, Caton-Deschamps, Blackburne-Pell, and plateau-patella angle (PPA) methods were retrospectively analyzed. Knee lateral radiographs taken in at least 30 degrees of flexion and appropriate rotation were scanned. All measurements were made by two orthopedic surgeons who were blinded to measurement methods. RESULTS: Right knee patellar height measurements were conducted in 56 patients, while left knee patellar heights were assessed in 52 patients. The highest inter-observer concordance was found in the fibula-condyle-patella angle. The second highest concordance was found in the Insall-Salvati. The highest concordance correlation was found with PPA in the measurements of both researchers. CONCLUSION: The fibula-condyle-patella angle is a reliable technique with a good inter-observer reliability for measuring patellar height. We believe that this study will inspire future research to establish comprehensive reference values for clinical applications.

Common radiographic indices used to measure patellar height do not consistently identify patella alta and lack interchangeability between measurements.

PURPOSE: Abnormal patellar height has been identified as a source of aberrant mechanical functioning within the patellofemoral joint. The purpose of this study is to examine the statistical agreement among three commonly used classification methods: Blackburne-Peel (BPI), Caton-Deschamps (CDI) and Insall-Salvati (ISR), by evaluating (1) the rates of patella alta identification and (2) the ability for one index to predict another. METHODS: One hundred lateral knee radiographs were evaluated using BPI, CDI and ISR to classify each knee as patella normal, patella alta or patella baja. Linear regression analysis was performed to evaluate the relationship between each index. Conversion equations were then derived using the reported linear regression best-fit line, comparing each pair of indices. RESULTS: Patella alta was identified in 15 knees using BPI, 15 using CDI and 25 using ISR. A total of seven knees were classified as patella alta by all BPI, CDI and ISR. Statistical analysis revealed significant correlation (p ≤ 0.001) among BPI and CDI (R2 = 0.706), BPI and ISR (R2 = 0.328) and CDI and ISR (R2 = 0.288). Wilcoxon Signed-Rank test between the three indices revealed no significant difference between the means of converted and original indices. CONCLUSION: Despite their significant correlations and adequate reproducibility, variability between common patellar height indices render predictions and conversions between BPI, CDI and ISR inequivalent. Users of these indices must be aware of their incongruent properties when considering application to patients in the clinical setting. Furthermore, it remains unclear which patellar height measurement technique is the correct index to use in a given knee. This study highlights the need for further investigation to create a reliable and standardised method for identifying patella height. LEVEL OF EVIDENCE: Level IV.

Clinical and Computational Evaluation of an Anatomic Patellar Component.

BACKGROUND: Anatomic patellar components for total knee arthroplasty (TKA) have demonstrated favorable in vivo kinematics. A novel failure mechanism in TKA patients with an anatomic patellar component was observed prompting an investigation to identify patient- and implant-related factors associated with suboptimal performance. METHODS: A retrospective evaluation was performed comparing 100 TKA patients with an anatomic patellar component to 100 gender-, age-, and body mass index-matched patients with a medialized dome component. All surgeries were performed with the same posterior-stabilized TKA system with minimum of 1-year follow-up. Several radiographic parameters were assessed. A separate computational evaluation was performed using finite-element analysis, comparing bone strain energy density through the patella bone remnant. RESULTS: Patients with an anatomic patellar component had significantly higher rates of anterior knee pain (18 versus 2%, P < .001), chronic effusions (18 versus 2%, P < .001), and superior patellar pole fragmentation (36 versus 13%, P < .001) compared to those with a dome component. Radiographically, the anatomic group demonstrated more lateral patellar subluxation (2.3 versus 1.1 mm, P < .001) and lateral tilt (5.4 versus 4.0 mm, P = .013). Furthermore, there were more revisions in the anatomic group (7 versus 3, P = .331). On computational evaluation, all simulations demonstrated increased bone strain energy density at the superior patellar pole with the anatomic patella. Resection thickness <13 mm resulted in over 2-fold higher strain energy density, and negative resection angle of 7° resulted in 6-fold higher superior pole strain energy. CONCLUSIONS: Patients with an anatomic patellar component showed higher rates of anterior knee pain, chronic effusion, and superior pole fragmentation compared to patients with a dome patella, with higher superior patellar pole strain energy confirmed on computational evaluation. Avoiding higher resection angles and excessive patellar resection may improve the performance and survivorship of the anatomic patella.

Patellar Instability: Imaging Findings.

Patellofemoral instability results from impaired engagement of the patella in the trochlear groove at the start of flexion and may lead to pain and lateral patellar dislocation. It occurs most frequently in adolescents and young adults during sporting activities. Trochlear dysplasia, patella alta, and excessive lateralization of the tibial tuberosity are the most common risk factors for patellar instability. The main role of imaging is to depict and assess these anatomical factors and highlight features indicating previous lateral dislocation of the patella.

Relationship Between Prepatellar Fat Thickness and Bone Mineral Density.

OBJECTIVE: To evaluate the relationship between bone mineral density (BMD) by measuring the prepatellar fat thickness with knee radiography and to gain a measurement method that has not been done before in the literature. STUDY DESIGN: Cross-sectional descriptive study. Place and Duration of the Study: Department of Physical Medicine and Rehabilitation, Training and Research Hospital, Sanliurfa, Turkiye, between January and June 2020. METHODOLOGY: Patients' age, body mass index (BMI) data, prepatellar fat thickness (mm), L1-L4 total, bone mineral density femoral neck, femur trochanter major, and femur total T scores were recorded. The relationships between these three groups (normal, osteopenia, osteoporosis) and between prepatellar fat tissue measurement were evaluated. One-way analysis of variance (ANOVA) and Post Hoc Tukey tests were used in the analysis. RESULTS:  A statistically significant difference was found in terms of trochanter major T score measurements (X2 = 20.435; p <0.001) and BMI (X2 = 66.535; p <0.001) measurements of prepatellar fat thickness measurement. A statistically significant difference was found between the three groups in terms of prepatellar fat thickness measurement, L1-4 T-score, femoral neck, and femur total values (p <0.001). CONCLUSION:  Prepatellar fat thickness in postmenopausal Turkish women was positively correlated with BMD; BMD increases as the prepatellar fat thickness increases. This explains that perapatellar fat thickness creates a mechanical load on the bones and causes an increase in BMD. KEY WORDS: Osteoporosis, Fat thickness, Bone mineral density.

Management of complete intra-articular distal femur and patellar fractures in an achondroplastic young adult; small is challenging' revisited: a case-report.

BACKGROUND: People with achondroplasia exhibit distinct physical characteristics, but their cognitive abilities remain within the normal range. The challenges encountered during surgical procedures and perioperative care for achondroplastic individuals, are underrepresented in the existing literature. CASE PRESENTATION: In this report, the management of a 26-year-old North-African achondroplastic male is highlighted. The patient suffered a complete intra-articular distal femur fracture (AO/OTA 33-C1) and an ipsilateral patella fracture (AO/OTA 34-C1). The patient's unusual anatomical variations and the lack of suitable orthopedic implants posed significant surgical challenges, particularly in the context of a resource-limited developing country. Facial and spinal deformities, which are common in patients with achondroplasia, further complicated the anesthetic approach. CONCLUSIONS: The limited information on operative management of fractures in achondroplastic patients necessitated independent decision-making and diverging from the convenient approach where clear guidance is available in the literature.

Patellar osteochondritis dissecans: maturation-dependent patellofemoral joint characteristics.

BACKGROUND: The likelihood of healing of osteochondritis dissecans decreases with skeletal maturity and there are theories that abnormal biomechanical forces contribute to the development and progression of these lesions. OBJECTIVE: To characterize, according to regional skeletal maturity, the morphology and alignment indices of the patellofemoral joint on MRI in patients with patellar osteochondritis dissecans. MATERIALS AND METHODS: MRI examinations of patients with patellar osteochondritis dissecans obtained between January 2008 and May 2023 were retrospectively reviewed to determine regional skeletal maturity, osteochondritis dissecans lesion size and location, patellar and trochlear morphology (Wiberg/Dejour classifications), and to calculate trochlear sulcus angles, trochlear depth index, lateral trochlear inclination, Insall-Salvati index, Caton-Deschamps index, patellar tendon-lateral trochlear ridge, and tibial tubercle-trochlear groove distances. Values were compared between skeletally immature and mature groups. RESULTS: Sixty-eight children (22 girls, 46 boys, age: 14.0 ± 1.7 years) yielded 74 knees with patellar osteochondritis dissecans lesions, 14 (19%) of which were skeletally mature. The most common anatomic location was over the central patella [median ridge (34/74 - 46%) on the axial images and over the middle third (45/74 - 61%) on the sagittal images]. Overall, mean trochlear sulcus angle (high, 151 ± 11°), trochlear depth index (low, 2.8 ± 1.4 mm), and Insall-Salvati index (borderline, 1.3 ± 0.1) were abnormal for the entire sample. Skeletally mature knees were significantly more likely to have higher (more dysplastic) Dejour types when compared to skeletally immature knees (p < 0.01). Knees in the mature group, compared to immature, had significantly more abnormal mean lateral trochlear inclination (15 ± 8° vs. 19 ± 6°, p = 0.03) and patellar tendon-lateral trochlear ridge distance (5.55 ± 4.31 mm vs. 2.89 ± 4.69 mm, p = 0.04). Half of the knees had ≥ 4 abnormal features that predispose to patellofemoral maltracking; mature knees were significantly (p = 0.02) more likely to have a higher number of abnormal features (> 6 features, 7/14, 50.0%) versus immature knees (0-3 features, 33/60, 55.0%). CONCLUSION: In children with patellar osteochondritis dissecans, abnormal patellofemoral morphology and alignment indices were common in all patients and more severe in mature knees.

Reconstruction of the extensor mechanism using polypropylene mesh in a displaced pathological fracture of the patella affected by giant cell tumour.

A man in his 30s came to our clinic with a year-long history of progressive pain and swelling in his knee. Diagnostic imaging revealed a displaced patellar fracture with an osteolytic, septated lesion and thinned expanded cortex in both fracture fragments. A core needle biopsy confirmed the diagnosis of giant cell tumour. Treatment involved wide excision of the tumour and the use of polypropylene mesh and a peroneal longus tendon autograft to reconstruct the extensor mechanism of the knee joint. One year postoperatively, the patient experienced no pain, demonstrated full range of motion and showed no signs of functional impairment or local tumour recurrence. This case highlights that reconstruction of the extensor mechanism of the knee after tumour excision with synthetic mesh is an affordable, user-friendly and widely accessible method. It can address large defects effectively while minimising the risks of disease transmission and graft lengthening, resulting in satisfactory outcomes.

Recurrent patellar dislocation patients with high-grade J-sign have multiple structural bone abnormalities in the lower limbs.

PURPOSE: To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD). METHODS: A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ2 test was used to compare composition ratio differences of structural bone abnormalities among the groups. RESULTS: A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001). CONCLUSION: In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures. LEVEL OF EVIDENCE: Level III.

Patho-morphology of patellar instability in children and adolescents: A systematic review and meta-analysis.

BACKGROUND: Children and adolescents have the highest incidence of patellar instability among the population. We aimed to identify patho-morphological and epidemiological factors associated with patellar instability, and to identify factors predisposing to recurrence in children and adolescents. METHODS: Published and unpublished literature databases, conference proceedings and the reference lists of included studies were searched to the 14th of March 2024. Studies were eligible if they compared history characteristics, examination features and radiological parameters between patients with and without instability, or evaluated risk factors for instability recurrence. A random-effects meta-analysis was performed. Included studies were appraised using tools respective of study design. RESULTS: The evidence was moderate to low in quality. Forty-five studies (including 9000 patients) were eligible. Tibial tubercle - tibial groove (TT-TG) distance (weighted mean difference [WMD] 5.96 mm, 95% Confidence Interval [CI]: 4.94 to 6.99 mm), sulcus angle (WMD: 13.93˚, 95% CI: 9.1˚ to 18.8˚), and Insall-Salvati index (WMD: 0.2, 95% CI: 0.16 to 0.23) were greater in patients with patellar instability. Risk factors for recurrent dislocation included age less than 18 years (Odds ratio [OR]: 2.56, 95% CI: 1.63 to 4.0), skeletal immaturity (OR: 1.79, 95% CI: 1.21 to 2.64) and presence of trochlear dysplasia (OR: 3.37, 95% CI: 1.85 to 6.15). CONCLUSION: Knowledge of patho-morphological factors associated with patellar instability could help explain its pathophysiological processes, allowing for the design of treatment approaches and the identification of patients at risk.

A retrospective investigation on clinical and radiographic outcomes of distal tibial fractures after intramedullary nailing using the lateral parapatellar extra-articular approach.

INTRODUCTION: According to reports, the modified extra-articular parapatellar approach allows the performance of tibial nailing in the semi-extended position without the concern of joint violation. However, there remains no special study that has provided a detailed assessment of the benefits and risks of this approach for treating distal tibial fractures (DTFs). The aim of this retrospective study was to investigate the clinical and radiological outcomes of patients with DTFs after intramedullary nailing using a lateral parapatellar extra-articular (LPE) approach in comparison to using the suprapatellar (SP) and transpatellar (TP) approaches. METHODS: Data were collected from 99 patients with a minimum follow-up period of 12 months. Comparisons were conducted between the groups regarding the number of intraoperative fluoroscopies, complications, knee pain, knee range of motion (ROM), the Lysholm Knee Scale (LKS), the Olerud-Molander Ankle Score (OMAS) and radiological findings. RESULTS: The demographic characteristics were comparable between the groups. Fewer intraoperative fluoroscopies were performed in the LPE (27.47 ± 4.98) and SP (26.03 ± 5.12) groups than in the TP group (30.20 ± 7.42; P<0.001). When compared with the other two approaches, the LPE approach was associated with less knee pain (P<0.001) and better knee ROM (P<0.001) at one week postoperative. No significant intergroup differences were detected in the incidence of complications, LKS scores (P = 0.687) and OMAS (P = 0.926). Radiological findings demonstrated that postoperative tibial alignment (P = 0.853), the time of bony union and rate of non-union were similar between the groups. CONCLUSION: The LPE approach can serve as a safe and effective option for tibial nailing, as it offers favourable outcomes in knee pain relief and knee ROM in the early postoperative period and is equivalent to the other two approaches in terms of the incidence of complications, fracture healing, functional recovery and postoperative alignment for patients with DTFs.

Patella Cartilage Status Does Not Affect the Clinical Outcomes of Non-resurfaced Patella in Mobile-Bearing Total Knee Arthroplasty.

Background: During total knee arthroplasty (TKA), patellar retention is performed when the cartilage is fairly well preserved and the thickness of the patella is relatively thin. However, clinical outcomes of the non-resurfaced patella in TKA according to the cartilage status are lacking in the literature. The purpose of this study was to compare patient-reported outcome measures (PROMs) according to the grade and location of the patellar cartilage lesion in TKA patients. Methods: The outcomes of 165 osteoarthritis patients (186 knees) who underwent cemented mobile-bearing TKA without patellar resurfacing were assessed and classified according to the grade and location of the patellar cartilage lesion. PROMs using the Western Ontario and MacMaster Universities Osteoarthritis index, the Knee Society Score (Knee Society Function Score and Knee Society Knee Score), and the Hospital for Special Surgery score were evaluated preoperatively and at postoperative 2, 4, 6, and 8 years. The correlations between PROMs and the grade and location of the cartilage lesion were assessed. Additionally, radiologic outcomes including the patellar tilt angle and patellar height were assessed and their correlation with the grade of cartilage lesion was analyzed. Analysis of variance was used to determine statistical significance. Results: There was no significant difference between PROMs according to the grades and locations of cartilage lesions at any postoperative follow-up. Radiologic parameters also showed no significant differences according to the grades of patellar cartilage lesions. Conclusions: The grade and location of the patellar cartilage lesion had no influence on clinical outcomes in mobile-bearing TKA with patellar retention at short- and long-term follow-up.

Effect of Patellar Morphology on the Risk of Osteochondral Fracture after Patellar Dislocation: A Cross-sectional Study.

OBJECTIVE: The risk of osteochondral fracture (OCF) after patellar dislocation has been shown to be related to patellofemoral anatomy, but its relationship to patellar morphology remains unknown. The aim of this study was to investigate the associations between patellar morphology and the risk of OCF after patellar dislocation. METHODS: A total of 140 patients with patellar dislocation between January 2018 and June 2023 were enrolled in this study and divided into two groups. Sixty-five patellar dislocation patients with OCF were included in the OCF group, while 75 patellar dislocation patients without OCF were included in the non-OCF group. Computed tomography was used to compare measurements of patellar morphology including Wiberg classification, patellar width and thickness, Wiberg angle, Wiberg index, facet ratio, lateral patellar facet angle, and patellar tilt angle. A logistic regression model was performed to evaluate the correlations between patellar morphology and the risk of OCF after patellar dislocation. Receiver operating characteristic curves were used to calculate the area under the curve (AUC) and determine the diagnostic values of patellar morphology for OCF after patellar dislocation. Subgroup analyses for gender and age were conducted to compare the differences in patellar morphology of PD patients. RESULTS: Wiberg angle was significantly lower in the OCF group (p = 0.017), while Wiberg index (p = 0.002) and facet ratio (p = 0.023) were significantly higher in the OCF group. According to the results of logistic regression analysis, Wiberg angle (odds ratio [OR] = 0.96, p = 0.022) and Wiberg index (OR = 1.105, p = 0.032) were the final relevant factors for the occurrence of OCF after patellar dislocation. The AUC was 0.622 (95% confidence interval [CI]: 0.529-0.714) for Wiberg angle, 0.65 (95% CI: 0.558-0.742) for Wiberg index, and 0.702 (95% CI: 0.615-0.788) for the combination of Wiberg angle plus Wiberg index. CONCLUSION: Wiberg angle and Wiberg index were independent risk factors for the occurrence of osteochondral fracture after patellar dislocation. Moreover, Wiberg angle, Wiberg index, and the combination of Wiberg angle plus Wiberg index had good predictive diagnostic value for the occurrence of OCF after patellar dislocation.