Dislocation of Hand, Thumb and Fingers: Types, Causes, Symptoms, Signs, Investigations

Joints in hand, thumb and finger includes carpometacarpal (Wrist) joint, metacarpophalangeal (knuckle) joint and interphalangeal (finger) joint. Metacarpal bones lie in palm of the hand and phalanges lies in thumb and fingers. Dislocation of the joint in hand, thumb and fingers are often seen following sport injury and domestic fall. Dislocation is caused by direct forceful impact, forceful twist of the bones of the joint or high-energy muscle contraction in opposing directions. Dislocation of the joint may be associated with fracture of the metacarpal bone or phalanges. Associated soft tissue injury such as tendon and ligament tear or dislocation is often ignored during the examination and later during treatment.

Hand is made up of several bones and joints. Hand is divided in palm, thumb and fingers. Total number of bones found in palm, thumb and fingers are 19.

• Bones of Palm- 5 Metacarpal Bones
• Bones of Thumb- 2 Phalanges
• Bones of Four Fingers- 12 Phalanges

Joint is a link between proximal and distal bones. Dislocation is a disruption of the link resulting in separation of proximal and distal bone.

• 4 DIP joints of 4 fingers are closest to the fingernails.
• Most common cause of dislocation is trauma.
• Dislocation is often associated with skin laceration or open wound.
• DIP dislocation is uncommon because of tough flexor and extensor tendons are tightly roped around the anterior and posterior surface of the joint.
• Dislocation is often associated with fracture.

• PIP joint is the middle joint of the fingers.
• Dislocation of PIP joint is known as “Jammed Finger.”
• Most frequently injured joint in hand.
• Dislocation is often caused by twist of free finger or forceful bend of the partially bent finger.
• PIP dislocation results from domestic fall or sports injuries.
• Accelerating forceful impact of partially bent finger is often observed during contact sports such as ice hockey, football and basketball.
• Direction of dislocation is ventral (toward palm), dorsal (toward back of the hand) or lateral (sideway) direction.
• Common dislocation and majority of dislocation in dorsal direction.

• Thumb has only one interphalangeal joint.
• Dislocation of IP joint of thumb is rare.
• Most of thumb IP Joint dislocation is in dorsal direction and associated with fracture.
• Dislocation often causes rupture of the flexor pollicis longus.

• MP joint link fingers (proximal or first phalanges) with palm (metacarpal bone) and forms the knuckles,
• Dislocation is rare, very stable joint.
• Dislocation mostly involves joint of little and index finger.
• Dislocation is associated with tear of collateral ligaments and tendon.
• Dislocation is often dorsal (back of the hand) in direction and causes separation of proximal phalanges and metacarpal bone.

The dislocation of joints in hand, thumb and fingers are anterior, posterior or lateral. Dislocation or separation of link involves proximal and distal bone. Proximal bone is considered in normal anatomical position if not fractured. Dislocation is classified as anterior, posterior or lateral depending on position of distal dislocated bone. In rare cases multiple dislocation of finger is seen and treated.³

Distal dislocated bone lies anterior or ventral to proximal bone. Dislocated distal bone is considered as anterior dislocation when distal bone is shifted towards front surface of palm, thumb, or fingers.

Distal dislocated bone lies posterior or dorsal to proximal bone. Dislocated distal bone is considered as posterior dislocation when distal bone is shifted towards back surface of palm, thumb, or fingers.

Distal dislocated bone lies on inner or outer side of the proximal bone. Dislocated distal bone is considered as lateral dislocation when distal bone is shifted to inner or outer side of palm, thumb, or fingers.

• Fall often causes direct impact on bones forming joints. The force impact is higher in obese patient because of multiplication of acceleration by higher weight.
• Obese patient often end in dislocation of PIP or MP joint, when they fall over out stretched arm.

• Sedatives and anti-allergy medication influences the normal reflexes.
• Reflexes are less efficient.
• Serious injuries such as fracture and dislocations of hand may result with simple loss of balance or fall.

• Joints in hand and fingers are affected by rheumatoid arthritis.
• Joint is often overstretched because of excessive secretion of synovial fluid.
• Tear or dislocation of overstretched ligaments and tendon often causes dislocation of the joint in palm and fingers.

Anterior, posterior or lateral dislocation depends on the position of the hand and finger at the time of impact.

• Auto Accident
• Work Accident
• Sports Injury
• Domestic Fall
• Diseases- Rheumatoid Arthritis

Pain is either acute pain or chronic pain. Acute pain last for less than 3 to 6 months and chronic pain last for more than 3 to 6 months.

Dislocation of Joints in Palm-

• Dislocation of metacarpophalangeal (MP) joint involves separation of metacarpal bone and phalanges.
• Severe excruciating pain is felt over knuckles.
• Pain is associated with joint deformity.

Dislocation of Joints In Thumb And Fingers-

• Dislocation of interphalangeal Joint.
• Severe intractable pain is observed in one of the dislocated joint of the thumb and fingers.

Pain intensity is measured as visual analogue score (VAS). VAS zero is considered as no pain and VAS of 10 is considered as very severe pain. Pain is divided as mild, moderate, severe and very severe pain. Pain is severe to very severe following MP or IP joint dislocation.

• Mild pain is described as VAS of 1 to 2.
• Moderate pain is described as VAS of 3 to 5.
• Severe pain is described as VAS 6 to 8.
• Very severe pain is described as VAS 9 to 10.

• Duration of pain is often prolonged.
• Severe pain lasts until dislocation is corrected and later pain remains as moderate or mild pain.
• Dislocation often follows as chronic arthritis and pain continues as mild to moderate pain.

• Stabbing and burning pain in finger and palm.
• Pain is moderate at rest and severe to very severe with activities.

Patient complains of joint deformity in palm or finger.

Distal fragment of the finger is displaced resulting in anterior, posterior or lateral dislocation. The type of deformity observed on examination is anterior, posterior or lateral deformity.

• Deformity is observed as bump covered by soft tissue swelling over the knuckles.
• Soft tissue swelling is secondary to tissue edema or subcutaneous blood clots.

Patient complaints of difficulties in bending or moving finger at knuckles or mid fingers.

Patient is unable to move finger at PIP (middle finger) and DIP (distal finger and thumb) joint.

Patient is unable to move finger at knuckles.

• Bruises are caused by subcutaneous bleeding (hematoma).
• Bruises cause purple discoloration of the skin.

• Bruises are observed over back, front or side of the finger.
• Bruises are observed over dislocated middle of finger (PIP) or near tip of the finger or thumb (DIP) joint.

• Bruises are seen over knuckles or skin in front of MP joint.
• Bruises covers the skin linking palm to fingers and thumb.

Patient is unable to move fingers or thumb following dislocation of the joint in palm, thumb or hand.

• Distal fragment of the finger is deviated from the proximal fragments.
• Angle of deviation indicates the type of dislocation like anterior, posterior or lateral dislocation.

• Pain is provoked by examination such as touch and pressure.
• Intensity of tenderness is increased following touch or any attempts to move dislocated finger.

Patient with dislocation of Metacarpophalangeal joint is unable to grab any object in hand.

Patient will be able to hold the object in palm with the use of normal fingers.

X-ray examination is performed to evaluate dislocation of Interphalangeal (IP) Joint and Metacarpophalangeal (MP) Joint.

• Anterior dislocation
• Posterior dislocation or
• Lateral dislocation.

MRI may not be necessary to diagnose dislocation of hand and fingers. X-Ray often shows the clear picture of dislocation.

Indications for MRI are as follows-

• Evaluate and diagnose hairline fracture and comminuted fracture.
• MRI is also performed to confirm the X-Ray findings.

• Ultrasound is a high frequency sound wave.
• The high frequency sound waves are transmitted through the tissue of different density resulting in creation of computer generated real time image.
• Ultrasound is used to evaluate the fluid collection like pus and hematoma (blood clot).

White Blood Cell Count (WBC) – WBC count is increased if infection is associated with dislocation of metacarpal bone and phalanges.

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