Scaphoid bone

 

It is one of the carpal bones. The scaphoid bone is situated between the forearm and the hand. This bone form the radial border of the tunnel called the carpal tunnel. There are eight carpal bones among which the scaphoid is the largest bone. 

 

The carpal bones are arranged in two rows that are the proximal row and the distal row. The scaphoid bone is present in the proximal row.

 

Anatomy

 

What is the structure of the scaphoid bone?

 

This bone is present on the radial side of the wrist in the proximal row of the carpal bones. The scaphoid bone articulates with the five bones that are the radius, lunate, trapezium, trapezoid, and capitate. The greater portion of this bone is covered by articular cartilage.

 

Features of the scaphoid bone

 

The palmar surface of this bone is concave and possesses a tubercle to which the transverse carpal ligament is attached. The side of the scaphoid bone that is present near the wrist is triangular, convex, and articulates with the radius of the forearm and adjacent bones.

 

The lateral surface of this bone is narrow and the radial collateral ligament attached to it. 

 

The medial side has two faces in which one articulates with the lunate and the other articulates with the head of the capitate plus with the lunate.

 

The dorsal surface of the scaphoid bone is narrow and possess a groove to which various ligaments are attached.

 

Blood supply of the scaphoid bone

 

This bone receives its blood supply from the radial artery through palmar and dorsal branches. The palmar and dorsal branches provide an abundant supply to the distal and middle part but ignore the proximal part. The proximal part of the scaphoid bone depends on the retrograde flow. 

 

The dorsal branch of the radial artery supplies the middle and distal parts while the palmar branch only supplies the lower third of this bone.

 

Palpation

This bone can be palpated at the base of a structure called the anatomical snuffbox. The scaphoid bone can also be palpated in the palmar hand. 

 

Fractures

The fractures of this bone are common due to its connection with the two rows of the carpal bones. This bone heals very slowly due to the limited circulation of the blood to the bone. It is necessary to treat the fracture of the scaphoid quickly because when this bone to unite they cause post-traumatic arthritis. 

 

Types
The fractures of the scaphoid bone are classified into two types that are
1. Non-displaced fracture
2.  Displaced fracture

 

In the non-displaced fracture, the bone fragments line up correctly while in the displaced fracture the bone fragments move out of their normal position.

 

Causes
1. When you fall and your weight land on your palm
2.  Sport activities
3.  Vehicle Collisions

 


Symptoms 
The fracture of this bone cause pain in the snuffbox and on the medial side of the wrist. The pain may be severe except for some cases in which the pain is not severe. If the pain persists more than a day then it is the sign of the fracture and it becomes necessary for you to see a doctor.

 


Diagnosis
Diagnosis can be done in two ways that are the physical examination, and the tests. Physical examination.
During the physical, the doctor will look at the patient’s history and will ask the symptoms from the patient. The doctor will then examine the wrist and look for tenderness, swelling, bruising, and loss of motion. tests.
The tests include 
1. X-rays
2.  MRI
3.  CT scan.

 

Surgical treatment
The surgical treatment of this bone can be done through
1. Reduction
2.  Internal fixation.

 

Complications
The complications of the scaphoid fractures are
1. Nonunion
2.  Avascular necrosis
3.  Arthritis

 

What is the scapholunate ligament?

The scapholunate ligament is the ligament that binds the scaphoid and lunate bones. The rupture in this ligament may cause scapholunate instability.

 

Scapholunate instability

It is the condition that occurs due to the rupture in the scapholunate ligament. This condition may cause wrist instability. If this condition remains untreated it will wrist osteoarthritis that is called a scapholunate advanced collapse.

 

Diagnosis
This condition can be diagnosed through Watson’s test. The x-ray also shows the instability went the distance is more than 3mm. 

 

Treatment
Treatment depends upon the severity of the injury. In some cases, surgical reconstruction is required.

 

What is a presier disease?

It is a condition in which the vascular necrosis of the scaphoid bone occurs without a previous fracture. Many anatomists thought that it is caused by repetitive Microtrauma or steroids in combination with the defective supply of the blood to the proximal side of the scaphoid.

 

Diagnosis
Diagnosis of the presier disease can be done through
1. MRI
2.  X-ray
3.  CT scan

Treatment 
Treatment options available for this condition are
1. Proximal row corpectomy
2.  Scaphoid excision
3.   Corner fusion

 

Following the above treatment options, it can take several months for the patient to recover. These treatments can significantly reduce the movement in the wrist because these are salvage procedures.

 

Nonunion of the scaphoid

This condition occurs when the scaphoid bone fracture fails to heal. Therefore it is necessary to treat the fracture. If the bone does not heal then the doctor may consider surgery and insert the bone graft. The grafts that are used mostly for the scaphoid fracture are the vascularized graft and structural graft.

 

Avascular necrosis of the scaphoid

It is the condition in which the fragment of the bone does not receive enough blood and its cells die. This condition occurs mostly in the displaced fractures. If this condition occurs the bone will not heal properly. To treat this condition doctors used vascularized graft but this helps when arthritis has not developed in the wrist.

 

Arthritis

The nonunion and avascular necrosis of the scaphoid bone may cause arthritis of the wrist. Arthritis occurs in this bone when the articular cartilage is worn.

 

Symptoms
1. Aching
2.  Stiffness
3.  The decrease in range of motion
4.  Pain