Background: The ideal points for medial patellofemoral ligament (MPFL) reconstruction have not been precisely defined. Purpose: To determine at which flexion angles the grafts should be fixed to best restore patellar stability as well as to compare the length change of various femoral and patellar fixation sites for current MPFL reconstruction during knee flexion in vivo. Study Design: Descriptive laboratory study. Methods: The right knees of 10 living patients were scanned with a high-resolution computed tomography scanner at 0°, 30°, 60°, 90°, and 120° of knee flexion, and 3-dimensional knee models were constructed using customized software. Based on recent anatomic studies and current surgical techniques, 4 femoral points (A: adductor tubercle; B: midpoint between the medial epicondyle and the adductor tubercle; C: medial epicondyle; and D: 10 mm inferior to the adductor tubercle) and 2 patellar points (30% [point 1] and 45% [point 2] from the proximal pole of the patella) were marked. The lengths of the 8 ligaments were digitally measured, and the length changes of these ligaments at the 5 different knee flexion angles were calculated. Results: Two ligaments including the adductor tubercle (A1, A2) showed an increase while the knee was flexed over 60°. Four ligaments (B1, B2, D1, D2) showed a slight increase as the knee flexed from 0° to 30° and a decrease as the flexion angle exceeded 30°. Length changes in these 6 ligaments were not significantly different. There was no significant difference between 2 patellar points in the length changes of these 6 ligaments. Two ligaments including the medial epicondyle (C1, C2) showed an excessive decrease during knee flexion and showed greatest length changes. Conclusion: The femoral fixation sites should be located at point B or point D. Point A and point C are not ideal femoral fixation sites. The best angle for graft fixation would be near 30° of knee flexion. Clinical Relevance: The data obtained for length and length change pattern in each virtual ligament will serve as a useful basis for improved MPFL reconstruction.
T1-weighted images showed low signal masses with foci of high signal intensity in 73% of cases. Tumors enhanced in a variety of patterns after the administration of Gd. Soft tissue masses extending anteriorly were seen in all cases with posterior extension in 77% of cases. The posterior masses involved the surrounding muscles and extended toward the greater sciatic notch, appearing with pseudopodia (87%). Sacroiliac joints were involved in 23% of cases. Four lesions showed intraspinal extension and involvement of the posterior spinal muscles above the level of bony involvement. In 6 patients recurrent tumors were found at or around the surgical margin of the tumor 6 months to 5 years after resection of the sacral tumor. In two of the patients, nodular metastases to the pelvic bones and femur were found 1-4 years after initial examination. In conclusion, MR imaging is useful in the diagnosis and preoperative assessment of sacrococcygeal chordoma. Characteristic findings included sacral mass with heterogeneously high signal intensity with crisscrossing septa on long-repetition-time imaging, well-encapsulated pseudopodia-like or lobulated appearance, and gluteal muscle infiltration. Follow-up MR imaging is helpful to assess for recurrent or metastatic lesions of chordomas.
Additional use of oblique coronal MR imaging of the knee improves diagnostic accuracy in the grading of ACL injury.
Nuchal-type fibroma, first described in 1988 by Enzinger and Weiss, is a rare fibrous growth occurring predominantly in the interscapular and paraspinous regions. It is typically located in the subcutaneous tissue of the posterior neck but may occur in extranuchal soft tissue sites such as the upper back, shoulder, and facial regions. In this article, we describe the magnetic resonance imaging findings of a nuchal-type fibroma that involved the buttock in a 45-year-old woman, and we review and discuss the literature on the subject.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.