What types of fractures can occur in the hand?
Hand fractures can be divided into four groups:
- fractures of the carpal bones
- fractures of the thumb and its metacarpal
- fractures of the finger metacarpals
- fractures of the fingers
This list is provided for completeness and to demonstrate the variety of hand fractures that have been recognized.
Fractures of the Carpal Bones
This is a common injury representing 70% of fractures in the carpal bones and 10% of all hand fractures. It is usually caused by a fall onto an outstretched hand that twists the wrist to the thumb side. It causes pain and tenderness at the base of the thumb near the wrist. These symptoms are sometimes unwisely ignored and the opportunity to treat this fracture early is lost. Scaphoid fracture has a bad reputation for malunion, failure to heal (nonunion) and avascular necrosis. This bone can also be broken when the wrist is dislocated. Stable scaphoid fractures are treated in a cast while unstable fractures may be treated by surgical fixation (ORIF). Scaphoid fractures can be subdivided into fractures of the distal pole, the waist, the proximal pole and the scaphoid tubercle. These fractures all behave differently and have different outcomes.
This bone may be crushed by a direct impact onto the heel of the hand. There is not much distortion of the bone usually but healing is a problem. The bone is almost completely covered by joint surface so the blood supply enters in only two small areas. Fracture can often damage the blood supply to the entire bone or portions of the bone, causing problems with healing and avascular necrosis. Fractures diagnosed early are treated by splinting the wrist in a cast.
A fracture of the triquetrum is usually caused by a direct blow on the back of the hand or by bending the wrist back too far. They can be separated into triquetral chip fractures which are treated non-operatively and fractures of the entire bone. Displaced fractures that involve large fragments may be treated with open or closed reduction and fixation.
Fractures of the trapezium usually result from a direct blow on the back of the hand. They are divided into fractures of the trapezial ridge which are treated in a cast and fractures of the entire bone. Undisplaced fractures can also be treated non-operatively. Displaced fractures that involve large fragments of the trapezium may be treated by surgery.
The trapezoid bone is well protected and is rarely injured on its own. When it is, the fracture usually heals without a problem.
Fractures of the capitate bone form 15% of all carpal fractures. Finding a fracture in the capitate should trigger a search for a wrist dislocation or an associated fracture of the scaphoid. In the rare case where the bone is injured on its own, it is caused by a load transmitted through the 3rd metacarpal. Undisplaced fractures are treated non-operatively; displaced fractures may be treated with open reduction and internal fixation surgery.
Fractures of the hamate affect either the entire bone or the hook of the hamate. Fractures of the entire bone are caused by direct trauma or by crushing the hand in machinery. Hamte fractures are commonly associated with unstable dislocations of the 4th or 5th metacarpals. Fractures of the hook may be stress fractures, may be caused by direct trauma or be avulsion fractures. It is extremely common for patients to ignore their symptoms believing that they have sprained their wrist. It is also common for the fracture not to show up on routine x-rays; Computerized Tomography (CT) scans of the wrist may be needed to show up a fracture. Fractures of the entire bone may need surgical treatment because of the associated dislocation. Fractures of the hook can be treated non-operatively with rest and splinting. However, some studies have suggested that this fracture does not heal well and referral to a hand surgeon is advised.
The pisiform is on the palm side of the other carpal bones. It is injured by a direct blow to the palm resulting in pain and tenderness on the little finger side of the palm near the wrist. It will normally heal without intervention.
The wrist joint between the forearm and the hand may be dislocated by a severe force in either flexion ( wrist bent/pulled forwards) or extension (wrist bent/pulled backwards). A dislocation results when the bones that form part of a joint are forced out of their normal alignment with each other. The ligaments that hold the joint together are torn. After the injury, the joint may remain out of alignment. Because of the complexity of the joints and ligaments that make up the wrist joint, a wrist dislocation is a very serious injury and treatment of wrist dislocations is both complex and difficult.
Some wrist dislocations also cause a fracture of one or more carpal bones. One of the most common is the trans-scaphoid perilunar dislocation. This long name means that in addition to the wrist dislocation, the scaphoid is broken, the lunate is dislocated and the ligaments between the lunate and the radius are torn. This is a serious injury. But, if the dislocation goes back into place after the injury occurs, the only sign of injury on X-ray is a fracture of the scaphoid. What looks like a simple fracture of the scaphoid when the doctor looks at the X-ray is really a very serious wrist dislocation that includes multiple torn ligaments. Understanding what has really occurred is necessary to adequately treat these types of injuries.
Fractures of the Thumb Metacarpal
A Bennett's fracture is a fracture into the joint at the base of the thumb metacarpal. The fragments are usually separated by the pull of the abductor pollucis longus (APL) muscle. Closed reduction is not always successful in obtaining a good position because the pull of the APL muscle immediately causes it to displace again. To hold the fracture in an acceptable position, surgical fixation is usually required using metal pins or screws. There are a variety of operative interventions for treatment of this injury.
The Rolando fracture is a more complex fracture at the base of the metacarpal. The fracture has multiple fragments and the fracture lines form T or Y shaped fracture at the base of the thumb metacarpal. There is usually significant deformity and the fracture often requires closed reduction and fixation.
Fracture of the Thumb Metacarpal Shaft
Because of the mobility of the thumb this is a rare injury. It may be caused by getting the thumb trapped and twisted. It can often be treated non-operatively as the thumb will function well with some deformity of the metacarpal.
Fracture of the Thumb Proximal Phalanx
Skier's Thumb (Gamekeeper's Thumb)
The Skier's thumb is a common avulsion fracture at the base of the proximal phalanx. The attachment of the ulnar collateral ligament connecting the metacarpal to the proximal phalanx is pulled off - or avulsed. It is caused by the thumb being forced inwards stretching the ligament. As the name implies a common cause of the injury is getting your thumb caught in a ski-pole strap. The fracture itself is not very significant but it may not heal, causing a painful nonunion and instability of the joint. Many surgeons recommend operating on this fracture to replace and fix the piece.
Other fractures of the thumb proximal phalanx are similar to the proximal phalanges of other digits. (see below)
Fracture of the Thumb Distal Phalanx
The injuries to this bone are similar to fracture of the distal phalanges of the digits. (see below)
Fractures of the Finger Metacarpals
Fractures of the Metacarpal Head
The round end of the metacarpal which forms a joint with the proximal phalanx is called the head. When your fist is clenched the round bumps on the back of the hand are the metacarpal heads. A blow on a clenched fist can impact directly on the metacarpal head and break it. This is a serious injury which may well result in long term stiffness of the joint, malalignment of the finger, avascular necrosis or premature arthritis of the joint. This fracture is often treated by surgery to restore the shape of the bone as close to normal as possible.
Fractures of the Metacarpal Neck
The metacarpal is narrower just next to the head so this region is called the neck. Fractures most commonly occur here when the patient punches something or someone. Any of the finger metacarpals can break at the neck but the most common injury is at the little finger. The metacarpal head may also be rotated, or twisted in the wrong position. This can usually be corrected and held in the corrected position during healing with a splint.
The Boxer's fracture is the most common metacarpal neck fracture. It is often quite displaced and angled with the metacarpal head being pushed into the palm of the hand. The shape of the metacarpal head allows for a great deal of movement at the joint. Even if the reduction is not perfect the joint will be able to move through a full range. The standard treatment for this fracture is to do a closed reduction, splint the hand in the position of function (wrist extended and MCP joints flexed 70°) and allow the fracture to heal. Residual angulation of 40° or less is acceptable but it is necessary to obtain follow-up X-rays to make sure it does not increase.
Metacarpal neck fractures may heal - with or without treatment - with the metacarpal head bent forward or in flexion. If this is too great, the deformity may result in a pain in the palm when using a forceful grip. This occurs due to the overly flexed head of the metacarpal sticking into the palm. This problem is much less likely to occur in the fifth finger (the Boxer's fracture), less likely in the fourth finger - but much more likely in the second and third fingers. This deformity may require surgery, either at the time of the injury or after the fracture has healed, to correct this deformity. Surgeons are much more likely to recommend surgery immediately if the deformity occurs in the second or third fingers.
Fractures of the Metacarpal Shaft
Fractures of the metacarpal shaft can occur in any of the fingers. Fracture of multiple bones is quite frequent when a heavy load drops on the back of the hand. Malrotation and flexion deformities can occur due to displacement in these fractures.
Malrotation means that the two ends of the metacarpal bone are twisted, or rotated, into an unacceptable position. This can cause problems if the bones are allowed to heal in this position because it also causes the finger attached to the end of the metacarpal to twist as well. When you try to close the hand and make a fist, the fingers overlap due to the deformity. This can be disabling and needs to be corrected. Usually, this deformity can be controlled with a good splint that places the hand in the correct position while the bone heals.
The flexion deformity that commonly occurs after a metacarpal shaft fracture is caused to the pull of the muscles in the hand. The muscle pull results in the angulation of the two fragments such that the distal end folds into the palm. If the bone is allowed to heal this way, it can result in difficulty with heavy gripping.
The second and third (index and long finger) metacarpals are immobile at their joints with the carpal bones. There is no way for the hand to adapt well to residual deformity in these two metacarpals. Most hand surgeons recommend that fractures of shaft in these two metacarpal bones need to be reduced anatomically. Ring and little finger metacarpals can tolerate a small amount of angulation.
Fractures of the Metacarpal Base
Fractures of the base of the metacarpals are quite unusual. Because there is very little movement at the carpometacarpal (CMC) joints of the index and long fingers it is not usually necessary to intervene. They are usually the results of an impact on the back of the hand and other bones may be broken. The little finger CMC joint is much more mobile and is more frequently injured. Fracture of the base of this metacarpal may be associated with a partial or complete dislocation of the CMC joint. This injury may need surgical treatment.
Fractures of the Fingers (Phalanges)
Fractures of the proximal and middle phalanges are close to the flexor tendon sheaths. The tendons may be damaged by the fracture or tethered as a result of scarring in the tendon sheaths. When the fracture line is transverse directly across the bone, the fragments are often displaced. Injury to the flexor tendon or tendon sheath should be suspected but is difficult to test for because it is sore to move the finger. The fracture is caused by longitudinal (axial) compression in the line of the bone. A typical accident would be a blow onto a bent knuckle. The fracture is often unstable.
When the bone breaks at an angle to the shaft it is referred to as oblique. This is usually the result of a bending force such as catching your finger in a door or a contact sports injury. This fracture is often unstable and may require ORIF.
When the force causing this type of injury is a twisting type injury, the fracture line is usually a spiral. This type of fracture is often displaced causing the finger to be out of alignment and unstable so that after reduction it does not stay in position. This may require surgical fixation (ORIF).
The head of the proximal phalanx forms one part of the joint with the middle phalanx (the PIP, Proximal Interphalangeal Joint). A fall on the knuckle or a force that drives the middle phalanx into the head may cause a multi-part (comminuted) fracture of the head. This injury usually needs operative treatment.
The metacarpo-phalangeal (MCP) joint is between the head of the metacarpal and the proximal phalanx. The proximal phalanx is flattened and slightly dished at this end. The two sides of the dished area are called condyles. A bending force may break off one of the condyles and a straight impact may break both. Because this is an intra-articular fracture the joint should be restored to smoothness and this frequently means surgery.
When the fracture is caused by axial compression along the axis of the bone, it usually causes a transverse type fracture. This usually occurs from a fall or a direct blow to the end of the finger. The fracture line is directly across the bone and the fragments are usually displaced. This fracture is often unstable and may need to be pinned.
The oblique fracture, where the fracture line is at an angle to the shaft of the bone, is caused by a bending force on the middle part of the finger. There is often some malrotation and angulation that needs to be reduced. This fracture is often unstable and may need surgery for the best result. If there is a lot of angulation the tendons may be injured also.
A twisting force on the finger may cause a spiral fracture pattern in the middle phalanx. The fracture is usually out of alignment and needs to be reduced. Because they tend to be unstable these fractures may need to be pinned.
The proximal interphalangeal (PIP) joint is the joint between the proximal and middle phalanx. If the finger is bent back at the PIP joint it may dislocate dorsally. This is referred to a volar plate avulsion fracture. When this inuury occurs, either the volar plate ligament ruptures or a small fragment of bone is pulled off from the base of the middle phalanx. The fracture involves a small area of the joint, not usually enough to be a concern. It can be treated by closed reduction of the dislocation and splinting in a flexed position. The bone fragment usually is in a position close to normal (anatomical). It is difficult to recover full range of the joint afterwards and some surgeons prefer to operate to replace the fragment and secure it so that the finger can be splinted straighter and move early.
The round end of the bone which forms a joint with the distal phalanx is called the head. A severe blow to the fingertip may drive the distal phalanx into the head causing it to shatter into several pieces. Because this is a fracture into the joint it may need to be treated by surgery to make the joint smooth.
The base of the middle phalanx forms the joint with the proximal phalanx. A blow or a twisting force may break the bone at this point. A displaced intraarticular fracture like this usually needs surgery to reduce the fragments accurately and make the joint surface smooth again.
Unfortunately, our fingers are often in harms way. Fingertip amputations are not uncommon and usually include injury to the bone of the distal phalanx. These injuries are most often caused by accidents with tools or saws. They frequently involve loss of the distal tuft of bone at the tip of the distal phalanx. The key to treatment is to obtain skin coverage of the bone end without shortening it too much.
Even when an amputation does not occur, a crush injury to the tip of the finger can cause a fracture of the tuft of the distal phalanx. These injuries commonly include a subungual hematoma. A subungual hematoma occurs when there is bleeding under the fingernail and a pocket of blood is trapped under pressure. It can be extremely painful and a hole may need to be made in the finger nail to allow the trapped blood to leak out. This usually relieves the pressure and the intense pain. This is the most common finger fracture and is caused by catching the fingertip in a car door or machinery. Normally it does not need intervention and will heal in a good position.
Not all of these crush injuries are simple. If the nail has been pulled out of the nail-fold and there is a fracture underneath, the fracture is open and contaminated. It needs to be treated as an open fracture with an operation to wash out the wound. The injury is caused by a bending or crushing force on the fingertip. Often the nail goes back into place after the accident and the wound looks insignificant.
Transverse fractures of the distal phalanx are usually stable but if angled may need closed reduction and surgical fixation with a pin. The force that causes this fracture is either a bending force on the fingertip or compression.
A special type of injury to the finger tip is the volar fracture dislocation or mallet finger. Immediately after this injury, the fingertip droops down and cannot be straightened. The attachment of the extensor tendon which straightens the finger has been pulled off. The injury results from a blow on the fingertip forcing bending of the joint when you are trying to straighten it. Typical accidents are sports injuries and falls. This fracture used to be treated by splinting in extension but because of stiffness some doctors prefer to operate on it to fix the fragment back in position.