Thumb Fractures

Introduction

Fractures of the base of thumb can cause considerable confusion. The culprit is the eponym- what is a Rolando Fracture on what is a Bennett Fracture? This page considers all aspects of plain film radiography of base of thumb fractures.

Anatomy

Epiphyseal Development

Radiographically visible primary ossification centres are seen at the bases of the phalanges and the distal ends of the metacarpals. The thumb is an exception where the thumb metacarpal ossifies like a phalanx (proximal ossification centre). The persistent expression of the distal epiphysis of the thumb metacarpal is called a pseudoepiphysis (top arrow). The pseudoepiphysis appears earlier than its standard counterparts, then fuses rapidly. Pseudoepiphyses have also been noted at the proximal ends of the finger metacarpals.

Base of Thumb Fractures- Rolando or Bennett Fracture or Neither?

Base of Thumb Fractures Lee F. Rogers Radiology of Skeletal Trauma, 2nd Ed, Vol 2,1992, p976

The distinction between these 5 fractures is frequently confused.

Bennett Fracture	Rolando Fracture	Base of Thumb Fracture
Oblique Intra-articular fracture of the base of the thumb with a triangluar fragment at ulnar base of metacarpal; - described in 1882 by Dr. Edward Bennett; - mechanism of fracture - results from axial blow directed against the partially flexed metacarpal; (ie. from fist fights) - involves an oblique intraarticular metacarpal fracture (known as the palmar beak fragment) which remains attached to the palmar beak ligament; volar fracture fragment remains attached to carpometacarpal by volar anterior oblique ligament - anterior oblique ligament anchors volar lip of metacarpal to tubercle of the trapezium; - hence, small volar lip fragment remains attached to anterior oblique ligament which is attached to trapezium; - distal metacarpal fragment (containing most of articular surface) is displaced proximally, radially, & dorsally by pull of abductor pollicis longus - displaced metacarpal is also rotated in supination by the pull of abductor pollicis longus <a class="external" href="http://www.wheelessonline.com/ortho/bennetts_fracture_dislocation" rel="nofollow" target="_blank">http://www.wheelessonline.com/ortho/bennetts_fracture_dislocation</a>	Comminuted intra-articluar fracture of the base of the thumb. - described in 1910 by Dr. Rolando - involves 3 part fracture at base of metacarpal - in addition to volar lip fracture (as seen with Bennett's fracture), there is also large dorsal fragment resulting in Y or T shaped intra-articular fracture - fracture is a comminuted intra-articular fracture at base of thumb metacarpal, even if Y or T is not present - fracture is uncommon but has a worse prognosis than a Bennet's fracture <a class="external" href="http://www.wheelessonline.com/ortho/rolandos_fracture" rel="nofollow" target="_blank">http://www.wheelessonline.com/ortho/rolandos_fracture</a>	This is a transverse fracture of the base of the thumb. It does not involve the joint and is therefore neither a Bennett nor Rolando fracture.

Game Keepers and Skier's' Thumb

History

Campbell originally coined the term gamekeeper's thumb in 1955, because this condition was most commonly associated with Scottish gamekeepers, especially rabbit keepers, in whomthe injury was work related. The injury occurred as themen sacrificed game such as rabbits; the animals' necks were brokenbetweenthe ground and the gamekeeper's thumb and index fingers. As a result, a valgus force was placed ontothe abducted metacarpophalangeal (MCP) joint, leading toan ulnar collateral ligament (UCL) injury andresulting in instability that was accompanied by pain and weakness of the pinch grasp.

Etiology

Gamekeeper's thumb is caused by a valgus force that is directed on the thumb metacarpophalangeal joint and produces a failure of the ulnar collateral ligament. Falls on an abducted thumb and the fall of a skier against a planted ski pole are common mechanisms.

<a class="external" href="http://emedicine.medscape.com/article/1239413-overview" rel="nofollow" target="_blank">Gamekeeper's Thumb</a>
<a class="external" href="http://emedicine.medscape.com/article/1239413-overview" rel="nofollow" target="_blank">Matthew Hannibal, Daniel Roger, MD, </a>
<a class="external" href="http://emedicine.medscape.com/article/1239413-overview" rel="nofollow" target="_blank">e medicine</a>

The ulnar collateral ligament nearly always separates from the base of first phalanx of the thumb - it frequently becomes lodged between adductor pollicis aponeurosis and its its normal position (Stener Lesion);
<a class="external" href="http://www.wheelessonline.com/ortho/gamekeepers_thumb" rel="nofollow" target="_blank">http://www.wheelessonline.com/ortho/gamekeepers_thumb</a>

<a name="IntroductionHistoryoftheProcedure"> </a>

<a class="external" href="http://skillbuilders.patientsites.com/Arthritis/Arthritis-Overview/preview_a%7E291/article.html" rel="nofollow" target="_blank"> http://skillbuilders.patientsites.com/Arthritis/Arthritis-Overview/preview_a~291/article.html (12/2/11)</a>	http://www.webmd.com/a-to-z-guides/skiers-thumb?page=4	<a class="external" href="http://blog.fitter1.com/WPC-edit-content/uploads/2010/04/b_14_1_2a.jpg" rel="nofollow" target="_blank"> http://blog.fitter1.com/wp-content/uploads/2010/04/b_14_1_2a.jpg</a>

Radiography

Stress Test

Stress applied to the ulnar collateral ligament of the thumb. No abnormal joint movement demonstrated.	Stress applied to the radial collateral ligament. No abnormal joint movement demonstrated.

Case 1

17 year old female with unknown history. There is an avulsion fracture of the ulnar aspect of the base of the proximal phalanx of the thumb.	The fracture is not demonstrated on the lateral projection image.

Case 2

31 year old male with unknown history. There is an avulsion fracture of the ulnar aspect of the base of the proximal phalanx of the thumb.	The fracture is not demonstrated on the lateral projection image.