The hand consists of five bones called metacarpal bones for all the five digits. The knuckles at the back of the hand are formed by the end of the metacarpal bones, which also assist or support the hand. Metacarpal fracture occurs when one of the long bones get injured. This could happen by performing certain activities like punch or direct impact to the hand due to which stress is placed on the metacarpal bones. As this kind of stress could be traumatic and beyond what the bone can withstand, an injury or a break in one or more metacarpals occurs. Thus, the condition is called as metacarpal fracture. In other words; metacarpal fracture can be termed as broken hand.
Bennett’s fracture is a condition in which the base of the metacarpal bone gets fractured where it articulates with the trapezium. Trapezium is one of the eight carpal bones in the wrist that forms a joint at the base of the thumb known as first carpometacarpal joint. The joint of the trapezium and thumb metacarpal base forms a saddle-like structure that aids significantly in the joints stability. This joint is covered by smooth cartilage at the ends of the metacarpal and trapezium, which allows easy articulation of the bones during motion.
Thumb joint is the only joint in the hand that has the ability to move in all directions.
Bennett’s fracture can be a result of injuries suffered during most of the contact sports such as boxing, rugby, and soccer.
Causes and Risk Factors of Bennett’s Fracture
Bennett’s fractures are mostly caused as a result of indirect forces such as falling on a thumb that is projecting out or a blow on a clenched fist. Punching is the most common mechanism, which leads to this type of fracture; however, there are many other reasons such as motor vehicle accidents, work related injuries and falls.
Bennett’s fracture is a severe type of fracture, which if treated inappropriately can lead to permanent disability with activities, which involve use of the thumb such as pinching.
Signs and Symptoms of Bennett’s Fracture
- Sudden pain and swelling in the wrist and thumb.
- Tenderness on touching the hand.
- Pain while attempting movement of hand.
- Thumb joint instability impairing the normal movement and activities involving thumb.
- Deformity of thumb.
Treatment for Bennett’s Fracture
- Generally, conservative route suffices for treatment of Bennett’s fracture where there is no significant displacement or rotational deformity. Conservative measures include closed reduction under local anesthesia and then casting or splinting of hand and thumb. Fracture may require at least six to ten weeks for complete healing, which includes period of immobilization for about six weeks followed by protective splinting for another six weeks.
- Thumb spica cast or splint is a specially designed cast or splint for treatment of Bennett’s fracture.
- Surgery may be recommended in severe cases where there are multiple fractures or open wound. Two factors play a major role in determining if surgery is warranted.
- Length: If the digit gets shortened or decreases in length due to fracture, surgery is recommended to restore the digit to its normal size.
- Rotation: In cases where the digit gets abnormally rotated due to the fracture, surgery is recommended to correct the deformity and restore the digit to its usual position.
- Metal implants such as plates, wires, and screws are used to fix the broken fragments of bone depending upon the nature and type of the fracture.
- The surgical procedure carries a risk of infection, bleeding, damage to neurovascular structures, and failure of hardware.
Exercises for Bennett’s Fracture
Stretching and strengthening exercises are required in the recovery phase to attain full motion of the digit.
Stretching Exercises for Bennett’s Fracture
- Flexion: This is done by bending the wrist forward until a pain-free stretch is sensed. This position need to be held for 5 seconds and should be performed in 2 sets of 15.
- Extension: This is done by bending the wrist backwards until a pain-free stretch is sensed. This position need to be held for about 5 seconds and should be performed in 2 sets of 15.
- Side to Side: This is done by moving the wrist from side to side until a pain-free stretch is sensed. This position need to be held for about 5 seconds in each direction and should be performed in 2 sets of 15.
Strengthening Exercises of Bennett’s Fracture
- Opposition Stretch: This is done by resting the hand on the table and palm in the upward direction. Join the tip of the thumb with the tip of the small finger. Hold this position for 6 seconds. Repeat for 10 times.
- Wrist Flexion: This exercise is performed by holding a hammer handle or soup can in the hand with palm facing the ceiling. Then, bend the wrist in the upward direction. Gradually decrease the weight and come back to the starting posture. Perform 2 sets of 15. Slowly increase the weight of the object.
- Wrist Extension: This is done by holding a hammer handle or a soup can in hands with the palm facing downwards. The wrist is then bent slowly in the upward direction. The weight needs to be decreased gradually when coming back to the starting posture. This needs to be performed in 2 sets of 15. Over time, the weight should be increased.
- Grip Strengthening: This is done by holding a tennis ball in the hand and squeezing it in the hardest possible manner without aggravating pain. It should be held for about 5 seconds and then released. It should be repeated about 5 to 10 times making sure there is no aggravation of symptoms.
- Finger Spring: This exercise is performed by wearing a rubber band around the outer surface of fingers including thumb. Stretch the rubber band by stretching the fingers. Perform 2 sets of 15.
Investigations for Bennett’s Fracture
A comprehensive history and physical examination is required for diagnosis of a metacarpal fracture. A thorough examination of the hand and the digits is performed to look for injuries to the nerves or vessels. An x-ray is generally required to confirm the severity. A prayer view may provide a good focused view of the metacarpal joint of the thumb.
Other Diagnostic Studies May Be: