First Carpometacarpal Joint Anatomy and Osteoarthritis: MR Imaging Overview

The first carpometacarpal (CMC) joint consists of seven ligaments. The magnetic resonance imaging (MRI) examination of the first CMC joint should be performed in a high field 1.5/3 T MRI with a dedicated hand coil for high-resolution images. Degeneration of anterior oblique ligament (AOL) is the most important cause for the development of osteoarthritis of first CMC joint. Since the AOL undergoes a predictable pattern of alteration at its metacarpal attachment as degeneration proceeds, MRI imaging can provide an accurate assessment of this ligament.

Trapezium and Bennett Fracture – A Rare Base Thumb Fracture Pattern:A Case Report

Introduction: Trapezium fracture is a rare entity whose treatment is controversial. The reported cases range from conservative treatment to surgical treatment with good reported results. Case Report: This paper reports a clinical case of trapezium-metacarpal fracture-dislocation associated with trapezius fracture and Bennett fracture, surgically treated with excellent functional and radiological results. The patient underwent open reduction and internal fixation with two screws, excision of fragments, and reinsertion of the anterior oblique ligament. At the year of follow-up, the patient presented no mobility limitations and recovered grip strength. Conclusion: This case study allows us to conclude that open reduction and internal fixation with screws of the dorsal trapezium ridge fractures with ligament repair of the anterior oblique ligament is a valid treatment with the reproduction of good clinical results. Keywords: Hand surgery, internal fixation, trapezium fracture.

The Anterior Oblique Ligament description in the knee anteromedial compartment

Purpose: To describe a ligamentous structure in the anteromedial region of the knee identified in a series of anatomical dissections of cadaveric specimens.Methods: Sixteen cadaveric knees were dissected to study the medial compartment. Exclusion criteria were signs of trauma, previous surgery, signs of osteoarthritis and poor preservation state. The main structures of this region were identified during medial dissection. After releasing the superficial medial collateral ligament (sMCL) of the tibia, the Anterior Oblique Ligament (AOL), was isolated. The morphology of the structure and its relationship with known anatomical parameters were determined. For the statistical analysis, the means and standard deviations were calculated for continuous variables. A 95% confidence intervals was defined as significant. Student's t-tests were used for continuous variables.Results: After dissection a distinct ligamentous structure (AOL) was found in the medial region of the knee. This structure was found in 100% of the cases, was located extracapsularly and originated in the anterior aspect of the medial epicondyle, running obliquely toward the tibia. When crossing the joint, the ligament presented a fan-shaped opening, exhibiting a larger area at the tibial insertion. The AOL had a mean thickness of 6.83±1.34 mm at its femoral origin and 13.06±1.91 at its tibial insertion. It had a significantly (p = 0.0009) longer mean length with the knee at 90° of flexion (33.82±9.50 mm) than with the knee in total extension (26.56±9.48 mm), indicating that the ligament is tensioned in flexion.Conclusion: A structure was identified in the anteromedial compartment of the knee with a ligamentous appearance originating in the medial femoral epicondyle and with tibial insertion anterior to the sMCL. Clinical relevance: This study demonstrates the anatomy of a new medial structure of the knee. As a result, there will be a better understanding of the stability of the knee.

The Effect of the Joint Capsule and Anterior Oblique Ligament on Dorsal Subluxation of the First Metacarpal During Key Pinch

Laxity of the anterior oblique ligament (AOL) and/or the dorsoradial ligament (DRL) are believed to contribute to the progression of osteoarthritis in the trapeziometacarpal joint through increased dorsal subluxation. Stress radiographs during functional tasks, such as key pinch, can be used to evaluate such joint instability. Cadaveric experiments can explore joint contact pressures as well as subluxation under varying conditions, to gain knowledge about joint mechanics. The disturbance of supporting tissues, such as the joint capsule, during experiments may affect the recorded stability of the joint. To evaluate potential effects of opening the joint capsule and severing the AOL, eleven cadaveric specimens were rigged to simulate key pinch. An anteroposterior (AP) radiograph of the hand was recorded for each specimen while intact, after partially opening the joint capsule and after sectioning the AOL. First metacarpal subluxation levels were compared between the intact joint, partially open joint capsule, and sectioned AOL. Neither opening the joint capsule nor cutting the AOL had a statistically significant effect on metacarpal subluxation. The results indicate that partially opening the joint capsule has a negligible effect on joint mechanics and support recent studies that postulate that the AOL plays a less substantial role in preventing subluxation.

Three-dimensional dynamic motion analysis of the first carpometacarpal ligaments

Purpose: The purpose of this study was to analyze the dynamic motion of the first carpometacarpal (CMC) ligaments on a three-dimensional (3-D) surface model and to examine the changes in the ligament lengths during the motion of the first CMC joint. Methods: Six fresh-frozen cadaver wrists were used to analyze the motion of the first CMC ligaments on a 3-D coordinate system using a digitizer. Four ligaments, namely, dorsoradial ligament (DRL), posterior oblique ligament (POL), superficial anterior oblique ligament (SAOL), and deep anterior oblique ligament (dAOL), were dissected and identified. Their attachments were digitized and represented on 3-D bone images. The distances between the ligament attachments of the first metacarpal and the trapezium, which were the ligament lengths, were measured during the extension–flexion and adduction–abduction of the first CMC joint. Results: Both the DRL and POL lengthened during flexion of the first CMC joint, and both the SAOL and dAOL lengthened during extension. Both the DRL and SAOL lengthened during adduction, and both the POL and dAOL lengthened during abduction. The DRL alone lengthened significantly at flexion and adduction when the first CMC joint was in dorsoradial dislocation. Conclusions: The lengths of four ligaments changed significantly during first CMC joint motion. This study suggested that the DRL contributes substantial stability to the first CMC joint, preventing dorsoradial dislocation. This 3-D information improves the knowledge and understanding of the function of individual ligaments and their roles in the stability of the first CMC joint.

Magnetic resonance imaging technology in evaluating the presence and integrity of the anterior oblique ligament of the thumb

The investigation examines the reliability and reproducibility of magnetic resonance imaging (MRI) technology in evaluating the anterior oblique ligament (AOL) of the trapeziometacarpal joint (TMC) of the thumb, in order to establish an effective imaging protocol to use in the early identification of conditions leading to degenerative arthritis. We used cadaver specimens, three hand surgeons independently rated from X-rays each specimen. The specimens were then scanned in a General Electric MRI machine with a standard wrist coil. An effort was made to reproduce the image of the AOL - with a unique technique to obtain images of the obliquely oriented thumb and its ligaments. Following the MRI, the specimens were dissected to expose the AOL and visualize the TMC joint. A standard MRI fiducial was sewn to the proximal and distal extent of the volar side of the AOL. The soft tissues were replaced and the skin was closed. They were then rescanned following the same protocol, and pre and post-dissection ligamentlabeled specimens were compared. Following dissection and tagging of the AOL ligament, a repeat MRI confirmed its location and validated the protocol in all cases. The open dissection and ligament tagging confirmed that what was visualized was in fact the structure of interest. This investigation demonstrated that with an appropriate MRI protocol it is feasible to guide the scanner to catch appropriate images of a ligament that is closely correlated with degenerative arthritis.