Hook of Hamate Fracture

The hamate is one of the many carpal bones of the hand and wrist. The Hamate bone is a triangular bone located in the distal carpal row situated on the ulnar side of the hand. The Hamate is composed of a body and a hook. The ulnar nerve passes through the Guyon’s canal between the Hamate and Pisiform ulnar nerve hamatebones. The ulnar nerve can become injured by a fracture of the body (rare) or by a fracture of the hook (common) which may cause neuropathy of the ulnar nerve within the Guyon’s canal. Missing the fracture can lead to persistent pain from nonunion. Hamate hook fractures are most often seen in racquet, bat, or club sports such as hockey and golf. Fractures of the Hamate bone are difficult to diagnose and routine x-rays may not show the fracture. Hook fractures of the Hamate are best seen by carpal tunnel x-ray views; however, a CT scan is the best study. The physician should rule out the ossification center (os hamuli proprium).

During the clinical evaluation, the physician should observe for hypothenar pain, as well as pain and paresthesia of the ring and small finger due to ulnar nerve compression in the Guyon’s canal. There may be weakness of intrinsics and a decrease in grip strength. The most common findings are pain and tenderness on the ulnar side of the wrists, distal to the wrist joint. The pull test is recently described. During the pull test, the palm of the hand is placed into supination. The wrist is in full ulnar deviation. Fingers of the patient should be flexed. The examiner pulls on the ulnar two digits with the patient resisting the pull. A positive test with pain in the area of the hook indicates a fractured hook of Hamate injury. Differential diagnosis include a pisiform fracture. When the physician is checking the Hamate hook for a fracture, if the ulnar side hook is normal, they should then check the pisiform bone. A CT scan may be necessary.

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Treatment for acute fractures include early immobilization for 4-6 weeks to avoid nonunion. For a symptomatic nonunion of the hook of Hamate, there will need to be an excision of the fracture fragment. An ORIF is rare.

 

 

Finger Fractures

Fractures to the fingers and hands are common. Mallet finger is a deformity caused from a blow to the finger at the DIP joint. Patient is unable to straighten the DIP due to avulsion injury.

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Most often mallet finger injuries can be treated without surgery. Treatment is given by applying a splint to immobilize the fingertip in extension. Movement should be allowed in the PIP joint. Surgery may be necessary if more than 50% of the joint is involved or there is subluxation of the joint to restore the function of the extensor tendon.

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Middle and proximal phalangeal fractures:

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The normal relaxed cascade of the hand should form a straight alignment of the fingers.  When holding a relaxed cascade, the fingers should normally point towards the region of the scaphoid. Malrotation of the finger will cause the affected finger to deviate from its normal rotational direction.

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Treatment:

If there is no rotational deformity, the finger is treated by buddy taping the injured finger to the adjacent normal finger for 2-3 weeks. If rotational deformity is present, a digital block is given and the fracture is reduced in a volar splint. The MCP is held in 70 degrees of flexion for proximal phalanx fractures for 2-3 weeks. The splint holds the DIP and PIP in 0 degrees extension in middle phalanx fractures. Then buddy tape for additional 2 weeks.

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Metacarpal fractures:

The wrist should be immobilized in 20 degrees extension and the MCP in 60-70 degrees of flexion.

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The fingers should be kept free in order to check for rotation. Finger fractures means stiffness of the fingers.

Indication for surgery:

  • Rotational deformity
  • Open fracture
  • Multiple unstable fractures
  • Significant angulation or deformity.
  • Articular displacement
  • Metacarpal shortening especially with the middle and index fingers.

If the fracture is displaced or unstable, closed reduction and K-wire is an option for fixation.

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Plating is another option for fixation however it is rare.

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In phalanx fractures treated by ORIF, adhesions of the extensor tendon may occur. Patient may have decreased range of motion of the PIP which is called extrinsic tightness.

The patient will have greater passive PIP flexion with MP extension compared to when MP is flexed.

 

What is Rheumatoid Arthritis?

Rheumatoid arthritis involves the synovium of the joints. The condition of rheumatoid arthritis will result in deformities. Rheumatoid arthritis occurs in females more than males.

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There may be a hereditary component with rheumatoid arthritis. Rheumatoid arthritis has spontaneous remissions and exacerbations. The disease can have a systemic nature. Pain and stiffness of joints especially in the morning (morning stiffness). Rheumatoid arthritis is typically poly-articular, bilateral, and symmetrical and most commonly affects the hands and feet.

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X-rays show periarticular erosions at the time of diagnosis. Osteopenia and minimal osteophyte formation favors the diagnosis of rheumatoid arthritis.

Pathogenesis

Rheumatoid is an auto immune disease. The disease has two important components: immunological reactions and increased degradative enzymes. The IgM (rheumatoid factor) is produced by the plasma cell as an antibody to the native IgG, which is altered in RA. 70% of the patients with RA have rheumatoid factor positive. Leukocytes are attracted to the immune complex forming deposits over the inflammatory surface of the synovium. These leukocytes ingest fibrin and immune complex and is called the rheumatoid cells. The leukocytes release lysosomal enzymes that causes acute inflammatory response and tissue necrosis as well as inflammatory mediators (IL-1, IL-6, and TNFα). The chondrocytes respond to stimulation by TNFα, IL-1 and other inflammatory mediators causing cells to become activated and secrete more metalloproteinases which lead to cartilage damage. The synovium becomes hypertrophied (Pannus), showing intimal hyperplasis and infiltration by plasma cells and lymphocytes.

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Stages of Rheumatoid Arthritis

Early stages (acute) include hot, swollen, tender joints (synovitis), wrist swelling, MCP swelling and Flexor Sheath Synovitis. Complicated rheumatoid arthritis include digital vasculitis, ecchymosis, skin atrophy and nodules. Advanced rheumatoid arthritis includes swelling of the MCP joints, lateral slippage of extensor tendons and tendon ruptures and ulnar deviation of fingers. X-rays show destruction of MCP with subluxation, ulnar deviation and wrist destruction.

Finger deformities include mallet, boutonniere, and swan neck.

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The thumb is also involved. These changes occur due to proliferation, inflammation and hypertrophy of the synovium. Involvement of the distal radioulnar joint is usually associated with rupture of the extensor digiti minimi.

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Rheumatoid Nodules

25% of patients with RA will have subcutaneous nodules on extensor surfaces of elbow and forearm. Nodules are often multiple and seen along the ulnar margin of the forearm or pulp of the digits. Vasculitis is more common in patients with SC nodules, it is a strongly seropositive disease (aggressive) with a less than favorable prognosis.

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Treatment

If the patient has synovitis, it should be treated by a splint and medical treatment. If the patient has joint space narrowing, bone erosions and osteopenia the patient will need a synovectomy. If the patient has joint destruction/fixed deformity or loss of hand function, surgery is based on the conditions.

Before operating on RA patients, x-ray of the cervical spine is needed because the patient may have subluxation of C1-C2. Metacarpophalangeal joint arthroplasty of the fingers usually results in decreased extensor lag and improvement of the ulnar drift.

Hamate Fractures

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Fractures of the hamate bone are rare, difficult to diagnose, and routine x-rays may not show the fracture. Hamate fractures are classified as either a hook fracture or as a body fracture.

Hamate hook fractures are usually seen in individuals who participate in sports which involve a racquet, baseball bat, or from swinging a golf club.

Swinging of the golf club may cause a hook fracture of the Hamate bone. Missing the fracture can lead to persistent pain from nonunion.

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Hamate body fractures are associated with axial force trauma, such as a fist striking a hard object, a fall, or from crushing injuries. It may also be accompanied by 4th and 5th metacarpal subluxation. Coronal fractures are the most common type of Hamate body fractures.

There are three types of coronal fractures; Type A (large piece), Type B (moderate piece) and Type C (avulsion). Make sure to watch out for subluxation of the joint due to pull from the Extensor Carpi Ulnaris.

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Hook fractures of the Hamate are best seen by carpal tunnel or supination x-ray views. For hamate fractures, CT scan is the best study. A 30° pronated view is helpful for body fractures.

Clinical Evaluation

Pain will be present, especially with axial loading of the ring and little finger or by grasping an object. The patient will have dismissed grip strength. They may have ulnar and median nerve neuropathy symptoms. The most common findings are pain and tenderness on the ulnar side of the wrist, distal to the wrist joint.

The pull test has been recently described. This is when the palm of the hand is placed into supination, the wrist is in full ulnar deviation, and the fingers of the patient should be flexed. The examiner pulls on the ulnar two digits with the patient resisting the pull. A positive test with pain in the area of the hook indicates a fractures hook of hamate injury. Pain may also be felt due to compression of the ulnar nerve in the Guyon Canal.

Treatment                        

Early immobilization for acute fractures with short arm splint for 6 weeks will be used to avoid a nonunion. For symptomatic nonunion, excision of the fracture fragment will be needed.

Types A and B require open reduction and internal fixation, in addition to stabilization of the joint if needed. Type C requires closed reduction and percutaneous pinning of the fragment for stabilization of the joint. If a closed reduction of the joint is not adequate, open reduction and stabilization of the joint should be done. A displaced fragment with subluxation requires reduction of the joint and stabilization of the joint with K-wires or fixation of the fragment.

When a 4th or 5th carpometacarpal dislocation occurs, one should make special effort to find a coronal fracture of the hamate.