Why does hyperextension develop at MCP joints?

Why does hyperextension develop at MCP joints?

Of note, hyperextension of the thumb MCP joint associated with TMC osteoarthritis is thought to be due to the dorsoradial subluxation of the thumb metacarpal base on the trapezium that is caused by the attenuation of the anterior oblique ligament, and adduction and flexion of the thumb metacarpal [2] .

What is MCP joint hyperextension?

Hyperextension of the middle joint of the thumb beyond a neutral position may result in a painful and unstable joint, decreased power, and difficulty in grasping large objects. Without stabilizing or “blocking” the hyperextension, the joint can become dislocated resulting in a loss of function.

What is a thumb MCP?

The finger bones are called phalanges. The metacarpophalangeal joint (MCP joint), or knuckle, is where the finger bones meet the hand bones. At the MCP joint, the fingers can move in multiple directions. They can bend, straighten, spread apart and move together. MCP joints are important for both pinching and gripping.

Does the thumb have an MCP?

Thumb. The MCP joint of the thumb consists of the articulation between the convex head of the first metacarpal and the concave proximal surface of the proximal phalanx of the thumb (Fig. 7.19). The basic structure of the MCP joint of the thumb is similar to that of the fingers.

How is hyperextension of the MCP measured?

Preoperative MCP joint hyperextension (defined as MCP joint extension beyond neutral) was measured in the clinic using a finger goniometer and recorded along with pre- and postoperative thumb radial and palmar abduction. Pre- and postoperative measurements of key and tip pinch were measured with a 13.6-kg pinch gauge.

What type of joint is thumb MCP?

synovial joints
Metacarpophalangeal (MCP) joints are condyloid type synovial joints between the metacarpal bones and proximal phalanges of the hands.

What is thumb abduction?

Abduction: Movement of the thumb away from the second metacarpal. ( Kaplan, 1984) This definition accommodates both palmar abduction as well as radial abduction. ( Reid & McGrouther: 1986) Flexion: Movement of the thumb perpendicular to plane of thumbnail across and parallel to the palm.

What are thumb joints called?

The thumb basal joint, also known as the carpometacarpal (CMC) joint, is a specialized saddle-shaped joint that is formed by a small wrist bone (trapezium) and the first of the three bones in the thumb (metacarpal).

What is thumb IP flexion?

Thumb Flexion. The motion occurs in the plane of the palm. The flexor pollicis longus is the only muscle able to flex the IP joint of the thumb.

What is thumb MP flexion?

The thumb MP joint allows flexion, extension, abduction, adduction, and a limited range of rotation. Flexion is to 115o, abduction/adduction of about 10o. The ulnar aspect has particular significance, with the adductor aponeurosis, an ulnar expansion of the dorsal aponeurosis, supporting the ulnar collateral ligament dynamically.

What is an extended thumb?

Extended thumb, index and middle finger. English: Gesture of extending thumb, index and middle fingers meaning “Holy Trinity”, or expressing Serbian identity. If the index and middle fingers are together (not separated), then it becomes the old “Hand of God” symbol.

What is thumb strain?

A sprained thumb (also known as a jammed thumb) is often the result of a repetitive action that strains the ligaments in the thumb. A ligament is soft tissue that connects bones to other bones, creating a complete joint.

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