BACKGROUNDNumerous studies have investigated the influence of osseous factors on patellofemoral joint instability, but research on the influence of dynamic muscle factors in vivo is still in the exploratory stage. This study aimed to use magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate vastus medialis oblique (VMO) fiber bundles in patients with recurrent patellar dislocation to explore the changes in muscle morphology and function.

METHODSThis prospective study involved 30 patients (7 males and 23 females; average age, 21.4 ± 3.8 years) clinically diagnosed with recurrent patellar dislocation in Peking University Third Hospital and 30 healthy volunteers matched for age, sex, and body mass index in our medical school between January 2014 and October 2014. None of the patients had a recent history of traumatic patellar dislocation or transient patellar dislocation. All patients underwent conventional MRI and DTI of the knee. The cross-sectional area of the VMO on MRI and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and primary (λ1), secondary (λ2), and three-level characteristic (λ3) values on DTI were measured. The independent-samples t-test was used to compare these parameters between the two groups.

RESULTSCompared with the control group, the patient group showed significantly higher FA values (0.39 ± 0.05 vs. 0.33 ± 0.03) and significantly lower ADC (1.51 ± 0.13 vs. 1.58 ± 0.07), λ2 (4.96 ± 0.13 vs. 5.04 ± 0.07), and λ3 values (4.44 ± 0.14 vs. 4.58 ± 0.07; t = 5.99, t = -2.58, t = -3.02, and t = -4.88, respectively; all P < 0.05). Cross-sectional VMO area and λ1 values did not differ between the two groups (t = -1.82 and t = 0.22, respectively; both P > 0.05).

CONCLUSIONSThe functional status of the VMO is closely associated with recurrent patellar dislocation. MRI, especially DTI (FA, ADC, λ2, and λ3), can detect early changes in VMO function and might facilitate the noninvasive monitoring of the functional status of the VMO in patients with recurrent patellar dislocation.

Adolescent ; Adult ; Child ; Diffusion Tensor Imaging ; methods ; Female ; Humans ; Knee Joint ; pathology ; Magnetic Resonance Imaging ; Male ; Patella ; pathology ; Patellar Dislocation ; diagnosis ; Prospective Studies ; Quadriceps Muscle ; pathology ; Sensitivity and Specificity ; Young Adult

OBJECTIVE: Our aim was to evaluate the cartilage cap of osteochondromas using T2 maps and to compare these values to those of normal patellar cartilage, from age and gender matched controls. MATERIALS AND METHODS: This study was approved by the Institutional Review Board and request for informed consent was waived. Eleven children (ages 5-17 years) with osteochondromas underwent MR imaging, which included T2-weighted fat suppressed and T2 relaxation time mapping (echo time = 9-99/repetition time = 1500 msec) sequences. Lesion origins were femur (n = 5), tibia (n = 3), fibula (n = 2), and scapula (n = 1). Signal intensity of the cartilage cap, thickness, mean T2 relaxation times, and T2 spatial variation (mean T2 relaxation times as a function of distance) were evaluated. Findings were compared to those of patellar cartilage from a group of age and gender matched subjects. RESULTS: The cartilage caps showed a fluid-like high T2 signal, with mean thickness of 4.8 mm. The mean value of mean T2 relaxation times of the osteochondromas was 264.0 +/- 80.4 msec (range, 151.0-366.0 msec). Mean T2 relaxation times were significantly longer than the values from patellar cartilage (39.0 msec) (p < 0.0001). These findings were observed with T2 spatial variation plots across the entire distance of the cartilage cap, with the most pronounced difference in the middle section of the cartilage. CONCLUSION: Longer T2 relaxation times of the cartilage caps of osteochondromas should be considered as normal, and likely to reflect an increased water content, different microstructure and component.
Adolescent ; Bone Neoplasms/*pathology ; Cartilage, Articular/*pathology ; Child ; Child, Preschool ; Female ; Femur ; Humans ; Magnetic Resonance Imaging/*methods ; Male ; Osteochondroma/*pathology ; Patella/*pathology ; Retrospective Studies ; Tibia

PURPOSE: The purpose of this study was to investigate the impact of varying knee flexion and quadriceps activity on patellofemoral indices measured on magnetic resonance imaging (MRI). MATERIALS AND METHODS: MRI of the knee was performed in 20 patients for indications other than patellar or patellofemoral pathology. Axial and sagittal sequences were performed in full extension of the knee with the quadriceps relaxed, full extension of the knee with the quadriceps contracted, 30° flexion of the knee with the quadriceps relaxed, and 30° flexion with the quadriceps contracted. Bisect offset, patella tilt angle, Insall-Salvati ratio and Caton-Deschamps index were measured. RESULTS: With the knee flexed to 30° and quadriceps relaxed, the mean values of patellar tilt angle, bisect offset, Insall-Salvati ratio and Caton-Deschamps index were all within normal limits. With the knee extended and quadriceps contracted, the mean patellar tilt angle (normal value, <15°) was 14.6° and the bisect offset (normal value, <65%) was 65%, while the Caton-Deschamps index was 1.34 (normal range, 0.6 to 1.3). With the knee extended and quadriceps relaxed, the mean Caton-Deschamps index was 1.31. CONCLUSIONS: MRI scanning of the knee in extension with the quadriceps contracted leads to elevated patellofemoral indices. MRI taken with the knee in 30° of flexion allows more reliable assessment of the patellofemoral joint and minimises the confounding effect of quadriceps contraction.
Humans ; Knee ; Magnetic Resonance Imaging ; Patella ; Patellofemoral Joint ; Pathology

It has been reported that the common sites of brown tumors are the jaw, pelvis, ribs, femurs and clavicles. We report our experience in a case of brown tumor of the patella caused by primary hyperparathyroidism. An initial radiograph and CT showed an osteolytic lesion and MR images showed a mixed solid and multiloculated cystic tumor in the right patella. One month after the parathyroidectomy, rapid bone formation was observed on both radiographs and CT images.
Adult ; Bone Density ; Bone Neoplasms/*etiology/radiography/*surgery ; Female ; Humans ; Hyperparathyroidism, Primary/*complications/*surgery ; Parathyroidectomy ; Patella/*pathology/radiography ; Tomography, X-Ray Computed

Adult ; Bone Neoplasms ; pathology ; surgery ; Female ; Giant Cell Tumor of Bone ; pathology ; surgery ; Humans ; Patella

A 14-year-old girl presented with left knee pain and swelling after an injury. Magnetic resonance (MR) imaging showed a transient lateral patellar dislocation with patellar osteochondral fracture, medial patellofemoral ligament tear and underlying femoral trochlear dysplasia. Open reduction and internal fixation of the osteochondral fracture, plication of the medial patellar retinaculum and lateral release were performed. As lateral patellar dislocation is often clinically unsuspected, an understanding of its characteristic imaging features is important in making the diagnosis. Knowledge of the various predisposing factors for patellar instability may also influence the choice of surgical management. We also discuss signs of acute injury and chronic instability observed on MR imaging, and the imaging features of anatomical variants that predispose an individual to lateral patellar dislocation. Treatment options and postsurgical imaging appearances are also briefly described.
Adolescent ; Arthralgia ; diagnosis ; Female ; Fracture Fixation, Internal ; Fractures, Bone ; diagnostic imaging ; pathology ; Humans ; Joint Instability ; Knee Joint ; diagnostic imaging ; Ligaments, Articular ; injuries ; Magnetic Resonance Imaging ; Patella ; diagnostic imaging ; pathology ; Patellar Dislocation ; diagnosis

OBJECTIVE: To analyse the effect of low intensity pulsed ultrasound stimulation (LIPUS) on accelerating the fibrocartilage layer repair of patella-patellar tendon junction. METHODS: A total of 60 mature female New Zealand white rabbits undergoing standard partial patellectomy were divided into 2 groups randomly. The control group was given comfort treatment and the treatment group was given LIPUS treatment starting from day 3 to the end of week 6 postoperatively. The scheduled time points of animal euthanization would be at week 6, week 12 and week 18 postoperatively. The patella-patellar tendon (PPT) complex would be harvested and cut into sections after decalcification for H&E staining, Safranine o/fast green staining. The thickness and gray value of fibrocartilage layer were analyzed by SANO Microscope Partner image analyzer. RESULTS: At week 6, week 12 and week 18 postoperatively, the fibrocartilage layer in the treatment group was significantly thicker than that in the control group (P<0.01), and the gray value of fibrocartilage layer was significantly smaller than that in the control group (P<0.01). CONCLUSION LIPUS helps to accelerate the fibrocartilage layer repair of patella-patellar tendon junction in rabbit models.
Animals ; Female ; Fibrocartilage ; pathology ; physiopathology ; Patella ; surgery ; Patellar Ligament ; injuries ; pathology ; physiopathology ; surgery ; Rabbits ; Tendon Injuries ; therapy ; Ultrasonic Therapy ; methods ; Wound Healing ; physiology

Adolescent ; Bone Neoplasms ; diagnosis ; pathology ; surgery ; Chondroblastoma ; diagnosis ; pathology ; surgery ; Humans ; Male ; Patella ; pathology

OBJECTIVE: We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. MATERIALS AND METHODS: Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast field echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. RESULTS: The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FS-PD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p < 0.01). CONCLUSION: The iw-FS-FSE images obtained with a microscopy coil show best diagnostic performance among the 2D and 3D GRE images for evaluating the chondromalacia patella.
Aged ; Chondromalacia Patellae/*diagnosis/pathology ; Female ; Humans ; *Imaging, Three-Dimensional ; Magnetic Resonance Imaging/instrumentation/*methods ; Male ; Middle Aged ; Patella/pathology ; Sensitivity and Specificity

Ehlers-Danlos Syndrome ; pathology ; Humans ; Lung ; abnormalities ; pathology ; Male ; Patella ; abnormalities