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.

Is It Possible to Perform Fifth Carpometacarpal Joint Arthroscopy? Cadaveric Study on Its Feasibility, Safety, and Potential Hazards in Portal Creation

Background Fifth carpometacarpal joint (CMCJ) fracture dislocation is a relatively rare injury and most will require operative treatment because of its unstable nature. Improper reduction and fixation lead to joint surface destruction, pain, and reduced grasping power. Intra-articular fragment reduction is often obscured by dorsally displaced ulnar fragment. Therefore, fifth CMCJ arthroscopy can be advantageous in assisting intra-articular fragment reduction. However, there is no detailed description of the portal landmarks or portals' relationship with adjacent important structures in the literature. Purposes To explore the feasibility and safety of fifth CMCJ arthroscopy, locations of the portals are examined in cadaveric hand specimens. Their proximity to important anatomical structures such as dorsal cutaneous branch of ulnar nerve (DCBUN), ring finger and little finger extensor digitorum communis (EDC), and extensor digiti minimi (EDM) is measured. Methods Fifth CMCJ arthroscopy is performed on 11 cadaveric hand specimens by specialist-level surgeon. The portals are marked and portal positions are further confirmed under the fluoroscopy. Then the cadaveric specimens were undergone anatomical dissection by specialist-level surgeon. During dissection, the spatial relationship between the portal positions and DCBUN, EDC to ring finger and little finger, and EDM is identified. The distance between the portals and the above important structures was measured in millimeters. Results DCBUN was consistently found between fourth metacarpohamate (4-MH) and fifth metacarpohamate (5-MH) portals, with it being closer to the latter (mean distance, 2.03 mm; range, 0–4.43 mm; standard deviation [SD], 1.09 mm). The closest tendon for 4-MH portal is ring finger EDC (mean distance, 2.65 mm; range, 0–5.89 mm; SD, 1.78 mm), while 5-MH portal and accessory portal were closest to EDC (mean distance, 1.88 mm; range, 0–3.69 mm; SD, 1.25 mm) and EDM (mean distance, 7.79 mm; range, 6.63–10.72 mm; SD, 1.49 mm), respectively. During the process of specimen dissection, we found no damage to the above structures after portal introduction. Conclusion The above findings support the use of fifth CMCJ arthroscopy, which can be used for assisted reduction in fifth metacarpal base fracture dislocation and hamate body fracture. Gentle soft tissue spreading technique during portal creation prevents injury to the important structure surrounding the portals. Level of evidence This is a Level V study.

Screw Fixation Method through Temporary Kirschner Wire Hole for Coronal Hamate Fracture

Purpose: Hamate coronal body fracture is a rare injury and often associated with dislocation of the carpometacarpal joint. For preserving the carpometacarpal joint, open reduction and rigid internal fixation is needed to displaced fracture. The purpose of this study was to evaluate the outcome of treating hamate coronal fracture with the screw fixation method through a temporary Kirschner wire (K-wire) fixation hole.Methods: From August 2016 to January 2021, eight patients who had displaced coronal hamate body fractures were enrolled. All patients were performed open reduction and multiple K-wires fixations. After that, the cortical screws were then inserted directly into the holes made by removing the K-wires one by one. The outcome measures were Disabilities of the Arm, Shoulder and Hand (DASH) scores and visual analogue scale (VAS) scores.Results: The average follow-up period was 11.5 months (range, 5–8 months) after surgery, and the bone union was observed at the 8 weeks after surgery. We confirmed that bone union had been completed for all the patients, and functional tests showed that the average DASH score was 3.95 (range, 0–8.3) and VAS score was 0.8 (range, 0–3).Conclusion: In coronal hamate body fractures, open reduction and screw fixation method through temporary K-wire fixation hole is simple and effective treatment technique.