Comparison of Habitual Versus Recurrent Patellar Dislocation in Children and Adolescents: Differences in Radiological Features.

Background: Recurrent patellar dislocation (RPD) and habitual patellar dislocation (HPD) in flexion are frequently encountered in children and adolescents. Purpose: To compare the radiological features of RPD and HPD in children and adolescents. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Imaging data were collected from patients aged 9 to 15 years who received surgical treatment for HPD or RPD at a single institution between June 2015 and September 2020. The prevalence of trochlear dysplasia, tibial tubercle lateralization, and lower limb rotational deformity was assessed through hip/knee/ankle computed tomography (CT) using the following quantitative indicators: trochlear depth index, lateral trochlear inclination, sulcus angle, tibial tubercle-trochlear groove (TT-TG) distance, ratio of TT-TG distance to femoral width, TT-TG angle, femoral anteversion angle, and tibial external rotation angle. The morphology of trochlea and patella were graded on knee CT using the Dejour and Wiberg classification. The Insall-Salvati index and Caton-Deschamps index were used to evaluate the height of the patella on lateral view radiographs. To evaluate lower limbs malalignment, the mechanical lateral distal femoral angle and medial proximal tibial angle were measured on weightbearing full-length radiographs. The collected data were analyzed and compared between the HPD and RPD groups. Results: Enrolled were 15 patients (21 knees) diagnosed with HPD and 18 patients (22 knees) diagnosed with RPD. The age of first dislocation was significantly younger in the HPD group (7.6 ± 3.4 vs 11.2 ± 1.4 years; P = 0.003). Knees in the HPD group had a significantly higher proportion of Dejour type C dysplasia (57.1% vs 4.5%; P < .005) and Wiberg type 3 patella (66.7% vs 9.1%; P < .001). There were statistically significant differences between the groups in the trochlear depth index (HPD vs RPD: 1.1 ± 1.7 vs 2.2 ± 1.5 mm; P = .039), sulcus angle (170.3° ± 13.7° vs 157.3° ± 16.0°; P = .007), Insall-Salvati index (1.1 ± 0.2 vs 1.3 ± 0.2; P = .034), and tibial external rotation angle (31.3° ± 7.8° vs 38.4° ± 8.5°; P = .009). Conclusion: Patients in the HPD group presented with poorer trochlear and patellar development, lower patellar height, and less tibial external rotation compared with patients in the RPG group.

Abnormal MRI signal intensity of the triangular fibrocartilage complex in asymptomatic wrists.

We investigated abnormal MRI findings of the triangular fibrocartilage complex in 154 asymptomatic volunteers (21-79 years). Except prevalence, we focused on the morphological features of abnormal signals in relation to age. The majority of full-thickness tears were located in the articular disc (63 participants). The incidence of disc perforation with characteristics of ulnar impaction syndrome increased significantly with age. Asymptomatic full-thickness tears of the ulnar attachment were found in ten participants (seven over 60 years old). The proximal and distal laminae of the ulnar attachment could not be differentiated in 36 participants. In conclusion, MRI is of limited value for the elderly in diagnosing triangular fibrocartilage disorders. For young subjects, MRI is still valuable, especially in diagnosing ulnar detachment, although the ability to distinguish between proximal and distal laminae remains questionable. Disc perforations in volunteers mimicked ulnar impaction syndrome, therefore age, clinical signs and other factors should also be considered in clinical diagnosis.Level of evidence: III.

Excessive proliferation and apoptosis of parathyroid cells contribute to primary hyperparathyroidism in rabbit model.

To explore the molecular pathogenesis of primary hyperparathyroidism (PHPT), we investigated the proliferation and apoptosis of parathyroid cells in a rabbit model of diet-induced PHPT. A total of 120 adult Chinese rabbits were randomly divided into normal diet (Ca:P, 1:0.7) group (control group) or a high-phosphate diet (Ca:P, 1:7) group (experimental group). The thyroid and parathyroid complexes were harvested for 1-month interval from month 1 to month 6. The expression of proliferation markers, including proliferating cell nuclear antigen (PCNA) and cyclin-D1, and B cell lymphoma-2 (Bcl-2), were evaluated by immunohistochemistry in thyroid and parathyroid tissues. Apoptosis was quantified by DNA-fragment terminal labeling. Our results demonstrated that parathyroid cells in the experimental group started proliferating from the end of the 2nd month, the expression of PCNA, Bcl-2, and cyclin-D1 were significantly higher in the PHPT group than those of the control group (p<0.05). Furthermore, the apoptosis index (AI) was positively correlated with the glandular cell count and expression of PCNA in the 6th month in the PHPT group. Overall, our results suggested that excessive proliferation and apoptosis of parathyroid cells may contribute to the pathogenesis of PHPT through PCNA-related, Bcl-2-related, and cyclin-D1-related pathways.

High-resolution 3T magnetic resonance imaging and histological analysis of capsuloligamentous complex of the first metatarsophalangeal joint.

BACKGROUND: There are discrepancies in the understanding of the structure of the capsuloligamentous complex of the first metatarsophalangeal joint (MTPJ); this study aims to investigate the differences with previous anatomical reports of high-resolution 3T magnetic resonance imaging (MRI) and histological analysis in illustrating the structure of the capsuloligamentous complex of the first MTPJ. METHODS: Nine fresh frozen cadaveric feet specimens (from two women and three men; aged 32 to 58 years) were used in this study. All specimens underwent MR examination with T1-weighted imaging and T2-weighted spectral attenuated inversion recovery in three planes. Subsequently, all cadaveric feet specimens were sliced into 2-mm-thick sections. The MRI features of the capsuloligamentous complex of the first MTPJ were analyzed in these specimens. Hematoxylin-eosin and Masson's trichrome staining methods were used to explore the histologic features of the capsuloligamentous complex of the first MTPJ. RESULTS: Different from most previous studies, our results showed that the plantar plate could be divided into four portions including the central portion of the plantar plate, the intersesamoid, the sesamoid phalangeal and the metatarsosesamoid ligaments. The normal central portion of the plantar plate could be clearly visualized in the sagittal and coronal plane MR images. The intersesamoid ligament is a continuation of the central portion of the plantar plate on the sagittal plane on the gross specimen, the MR imaging, and the histological examination. On the coronal plane of the gross specimen and MR imaging, the sesamoid phalangeal ligaments and the central portion of the plantar plate can be seen as separate ligaments, but they appeared interwoven with the same continuous collagenous fibers on the histological analysis. CONCLUSION: High-resolution 3T MRI allows accurate demonstration of the different anatomical details of the capsuloligamentous complex of the first MTPJ from previous anatomical reports. The histological analysis provides further understanding of the structures of the capsuloligamentous complex of the first MTPJ from previous studies.

Traumatic injury of the triangular fibrocartilage complex (TFCC)-a refinement to the Palmer classification by using high-resolution 3-T MRI.

OBJECTIVE: The aim of this study was to investigate the MR features of the traumatic injury of the triangular fibrocartilage complex (TFCC) by using high-resolution 3-T magnetic resonance imaging (MRI) and to refine the Palmer classification system. MATERIALS AND METHODS: From November 2015 to May 2019, sixty-seven patients met the including and excluding criteria and were enrolled into this retrospective study. All subjects had high-resolution 3-T MRI scan of the wrist and eleven had indirect MR arthrography of the wrist. All the MRI were read by two experienced musculoskeletal radiologists. Diagnostic sensitivity, specificity, and accuracy of MRI were calculated by using the arthroscopy and surgery as the standard of reference. A P value less than 0.05 was considered statistically significant. The interobserver agreement was assessed by kappa analysis. RESULTS: There were 49 cases of TFCC injuries proven by the arthroscopy or surgery. The TFCC injuries in the other 18 patients were proved by the combination of clinical follow-up examination and follow-up MRI. Among the arthroscopy- or surgery-confirmed cases, there were 32 patients with original Palmer injuries (IA = 10, IB = 19, ID = 3), 5 with capsular detachment, 4 with bucket-handle tear of the TFCC that have rarely been reported, and 8 with complex injuries that involved the listed classifications above. The sensitivities and specificities of MRI for diagnosing IA, IB, ID, complex injuries, and bucket-handle tear were 67-100% and 90-100%, and overall good to perfect interobserver agreements (kappa, 0.64-1.00). The diagnostic performance for the capsular detachment was lower (kappa, 0.38). CONCLUSION: With high-resolution 3-T MRI, more detailed injury patterns were found including capsular injuries, the horizontal tear of the articular disk, and the bucket-handle tear. It is necessary to refine the classic Palmer classification of TFCC injuries.

Sports Injury-Related Fingers and Thumb Deformity Due to Tendon or Ligament Rupture.

BACKGROUND: Hand injuries are very common in sports, such as skiing and ball sports. One of the major reasons causing hand and finger deformity is due to ligament and tendon injury. The aim of this study was to investigate if the high-resolution 3T magnetic resonance imaging (MRI) can demonstrate the complex anatomy of the fingers and thumb, especially the tendons and ligaments, and provide the accurate diagnosis of clinically important fingers and thumbs deformity due to ligamentous and tendinous injuries during sport activities. METHODS: Sixteen fresh un-embalmed cadaveric hands were harvested from eight cadavers. A total of 20 healthy volunteers' hands and 44 patients with fingers or thumb deformity due to sports-related injuries were included in this study. All subjects had MR examination with T1-weighted images and proton density-weighted imaging with fat suppression (PD FS) in axial, coronal, and sagittal plane, respectively. Subsequently, all 16 cadaveric hands were sliced into 2-mm thick slab with a band saw (six in coronal plane, six in sagittal plane, and four in axial plane). The correlation of anatomic sections and the MRI characteristics of tendons of fingers and the ulnar collateral ligament (UCL) at the metacarpal phalangeal joint (MCPJ) of thumb between 20 healthy volunteers and 44 patients (confirmed by surgery) were analyzed. RESULTS: The normal ligaments and tendons in 16 cadaveric hands and 20 volunteers' hands showed uniform low-signal intensity on all the sequences of the MRI. Among 44 patients with tendinous and ligamentous injuries in the fingers or thumb, 12 cases with UCL injury at MCPJ of the thumb (Stener lesion = 8 and non-Stener lesion = 4), 6 cases with the central slip injury, 12 cases with terminal tendon injury, and 14 cases with flexor digitorum profundus injury. The ligaments and tendons disruption manifested as increased signal intensity and poor definition, discontinuity, and heterogeneous signal intensity of the involved ligaments and tendons. CONCLUSIONS: Sports injury-related fingers and thumb deformity are relatively common. MRI is an accurate method for evaluation of the anatomy and pathologic conditions of the fingers and thumb. It is a useful tool for accurate diagnosis of the sports-related ligaments and tendons injuries in hand.

High-resolution 3-T MRI of the triangular fibrocartilage complex in the wrist: injury pattern and MR features.

OBJECTIVES: To investigate if using high-resolution 3-T MRI can identify additional injuries of the triangular fibrocartilage complex (TFCC) beyond the Palmer classification. MATERIALS AND METHODS: Eighty-six patients with surgically proven TFCC injury were included in this study. All patients underwent high-resolution 3-T MRI of the injured wrist. The MR imaging features of TFCC were analyzed according to the Palmer classification. RESULTS: According to the Palmer classification, 69 patients could be classified as having Palmer injuries (52 had traumatic tears and 17 had degenerative tears). There were 17 patients whose injuries could not be classified according to the Palmer classification: 13 had volar or dorsal capsular TFC detachment and 4 had a horizontal tear of the articular disk. CONCLUSION: Using high-resolution 3-T MRI, we have not only found all the TFCC injuries described in the Palmer classification, additional injury types were found in this study, including horizontal tear of the TFC and capsular TFC detachment. We propose the modified Palmer classification and add the injury types that were not included in the original Palmer classification.

High-resolution 3T Magnetic Resonance Imaging of the Triangular Fibrocartilage Complex in Chinese Wrists: Correlation with Cross-sectional Anatomy.

BACKGROUND: The injury of the triangular fibrocartilage complex (TFCC) is a common cause of ulnar-sided wrist pain. The aim of this study was to investigate if the high-resolution 3T magnetic resonance imaging (MRI) could demonstrate the detailed complex anatomy of TFCC in Chinese. METHODS: Fourteen Chinese cadaveric wrists (from four men and three women; age range at death from 30 to 60 years; mean age at 46 years) and forty healthy Chinese wrists (from 20 healthy volunteers, male/female: 10/10; age range from 21 to 53 years with a mean age of 32 years) in Beijing Jishuitan Hospital from March 2014 to March 2016 were included in this study. All cadavers and volunteers had magnetic resonance (MR) examination of the wrist with coronal T1-weighted and proton density-weighted imaging with fat suppression in three planes, respectively. MR arthrography (MRAr) was performed on one of the cadaveric wrists. Subsequently, all 14 cadaveric wrists were sliced into 2 mm thick slab with band saw (six in coronal plane, four in sagittal plane, and four in axial plane). The MRI features of normal TFCC were analyzed in these specimens and forty healthy wrists. RESULTS: Triangular fibrocartilage, the ulnar collateral ligament, and the meniscal homolog could be best observed on images in coronal plane. The palmar and dorsal radioulnar ligaments were best evaluated in transverse plane. The ulnotriquetral and ulnolunate ligaments were best visualized in sagittal plane. The latter two structures and the volar and dorsal capsules were better demonstrated on MRAr. CONCLUSION: High-resolution 3T MRI is capable to show the detailed complex anatomy of the TFCC and can provide valuable information for the clinical diagnosis in Chinese.

[MRI of the thumb collateral ligament at the metacarpophalangeal joint: anatomy and injuries].

OBJECTIVE: To explore the anatomy and injuries features of the thumb collateral ligamentat the metacarpophalangeal (MCP) joints. METHODS: The study was reviewed and approved by an institutional review board of hospital. Clinical imaging data of 7 healthy volunteers who without injuries and 20 patients with thumb collateral ligament injuries were retrospectively analyzed. All subjects underwent magnetic resonance examination, then comparative analysis of the normal anatomy and the thumb collateral ligament injury at MCP joints of MRI features in healthy volunteers and patients with injury. Imaging findings were compared with the surgical results and confirmed by followed up in patients. RESULTS: Seven volunteers without ligament injures showed homogeneous low-signal-intensity on T1-weighted and proton fat saturation sequence (PD-FS) images. The average thickness of the ulnarcollateral ligament is about 2.0 to 2.3 mm, however, the normal radial collateral ligament is thinner, the average thickness is about 1.4-1.5 mm. There were 20 patients with thumb collateral ligament injuresat MCP joints, including 12 cases of ulnar collateral ligament injury and 8 cases of radial collateral ligament injury, which demonstrated poor definition, discontinuity and heterogeneously increased signal intensity in proton fat saturation sequence (PD-FS) of the involved collateral ligament. There was edema in the soft tissues surrounding the injured sites. CONCLUSION: MRI is an accurate method for evaluation of the anatomy and pathologic conditions of the thumb collateral ligamentsat MCP joints, and it is a useful tool for early diagnosis and treatment of the thumb collateral ligaments injuries.

[Skeletal disease in primary hyperparathyroidism: X-ray, CT and MR imaging founding].

OBJECTIVE: To analyze the X-ray, CT and MR imaging findings in skeletal disease with primary hyperparathyroidism (PHPT), so as to discuss the clinic feature and differential diagnosis. METHODS: Thirty patients with PHPT were confirmed by surgery and pathological examination. In 15 patients the lesion were found in femur. There were 15 tibia, 12 fibula, and 14 iliac lesions. In three patients lesions were found in vertebrae. Three patients had lesions in humeri. In five patients lesions were found in rib. Twelve patients had lesions in phalanges. Thirty patients were studied preoperatively with radiographs, CT and MR imaging. The imaging findings were compared with the pathologic diagnosis and confirmed by double blind method. RESULTS: Radiographs of the bone in 30 patients showed generalised osteopaenia. There were 20 (66.7%) cases with bone resorption, which include 12 (40.0%) cases with subperiosteal resorption, 11 (36.7%) cases with cortical bone resorption, and 10 (33.3%) cases with subchondral resorption. There were 19 (63.3%) cases with osteitis fibrosa cystica/brown tumor. There were 5 (16.7%) patients sustained a pathological fracture. CONCLUSION: X-ray, CT and MR imaging founding reflect the imaging and pathology features in skeletal disease of PHPT. The iliac lesions could been found in common, and usually eroding sacroiliac joint. Skeletal disease of PHPT should be differentiated from osteolytic metastatic tumor of bone, osteodysplasia fibrosa, giant cell tumor of bone and aneurysmal bone cysts.