Abstract
- The upper arm has two muscle compartments: the anterior, which includes the biceps, and the posterior, which includes the triceps muscle.
- The forearm has two major compartments: the anterior containing the flexor muscles, and the posterior containing the extensor muscles. The mobile wad creates the third compartment.
- The upper extremity is perfused by branches from the deep and superficial brachial artery. The proximal brachial artery lies in the groove between the biceps and triceps muscles. Distally, it courses in front of the humerus. At the antecubital fossa, it runs deep to the bicipital aponeurosis and bifurcates into the radial and ulnar arteries, just below the elbow. The artery is surrounded by the two concomitant brachial veins, which run on either side of the artery.
- The profunda brachial artery is a large branch arising from the proximal brachial artery distal to the teres major muscle and follows the radial nerve closely. It provides collateral circulation to the lower arm.
- The basilic vein courses in the subcutaneous tissue in the medial aspect of the lower arm. At the midpoint, it penetrates the fascia to join one of the brachial veins.
- The cephalic vein is entirely in the subcutaneous tissues, courses in the deltopectoral groove, and empties into the junction of the brachial and axillary veins.
- In the upper arm, the median nerve lies in front of the brachial artery. It then crosses over the artery midway down the upper arm, where distally it lies posteromedial to the artery.
- The ulnar nerve is behind the artery in the upper half of the arm. Midway down the arm, it pierces the intermuscular septum and courses more posteriorly, away from the artery, behind the medial epicondyle.
Surgical Anatomy
The upper arm has two muscle compartments: the anterior, which includes the biceps, and the posterior, which includes the triceps muscle.
The forearm has two major compartments: the anterior containing the flexor muscles, and the posterior containing the extensor muscles. The mobile wad creates the third compartment.
The upper extremity is perfused by branches from the deep and superficial brachial artery. The proximal brachial artery lies in the groove between the biceps and triceps muscles. Distally, it courses in front of the humerus. At the antecubital fossa, it runs deep to the bicipital aponeurosis and bifurcates into the radial and ulnar arteries, just below the elbow. The artery is surrounded by the two concomitant brachial veins, which run on either side of the artery.
The profunda brachial artery is a large branch arising from the proximal brachial artery distal to the teres major muscle and follows the radial nerve closely. It provides collateral circulation to the lower arm.
The basilic vein courses in the subcutaneous tissue in the medial aspect of the lower arm. At the midpoint, it penetrates the fascia to join one of the brachial veins.
The cephalic vein is entirely in the subcutaneous tissues, courses in the deltopectoral groove, and empties into the junction of the brachial and axillary veins.
In the upper arm, the median nerve lies in front of the brachial artery. It then crosses over the artery midway down the upper arm, where distally it lies posteromedial to the artery.
The ulnar nerve is behind the artery in the upper half of the arm. Midway down the arm, it pierces the intermuscular septum and courses more posteriorly, away from the artery, behind the medial epicondyle.
General Principles
In many trauma cases with mangled extremity, primary amputation may be preferable to multiple and often futile, salvage attempts.
The level and type of amputation should be determined by the general condition of the patient, the functional status of the limb, the type and severity of associated fractures, the extent of soft tissue damage, the adequacy of blood supply, and the availability of healthy skin flaps to cover the stump.
Preserve as much functional length as possible to improve prosthesis fitting and functionality of the remaining limb.
Use tourniquets to minimize blood loss. Elevation of the arm and the use of bandage or tourniquet exsanguinator should be considered. The inflation pressure is usually set at about 250 mmHg in adults or about 100 mmHg above the systolic pressure.
All nonviable tissue must be removed.
Nerves should be sharply divided as high as possible and allowed to retract. The ends of the nerves should be away from areas of pressure.
Preserve sufficient soft tissues to cover the end of the bone without tension. However, avoid excessive amount of soft tissues because it may interfere with the skin closure and prosthesis fitting.
Bone edges should be filed to remove any sharp edges.
Wounds should be closed without tension and suture lines should be placed away from weight bearing surfaces when possible.
In the multiply injured patient in extremis, a guillotine amputation has been previously recommended. In contemporary settings, a skin-sparing damage-control amputation is the preferred intervention to preserve the soft tissues and skin for semi-elective completion when the condition of the patient stabilizes.
Special Instruments
Use a wide arm table board to rest the injured extremity.
Pneumatic tourniquet and bandage or tourniquet exsanguinator.
Power saw or Gigli saw.
Bone files or rasps and a periostal elevator.
Compression wraps for postoperative dressings are helpful to decrease edema and to shape the stump for early fittings of prosthetics.
Patient Positioning
Supine position, with the injured arm abducted 90° on an arm table board.
Skin preparation should include the hand and the whole arm circumferentially, up to the axilla and shoulder. The hand should be covered with a sterile stockinette. A Doppler probe should be in the sterile field to assess arterial supply.
Apply a sterile pneumatic tourniquet if possible.
Above Elbow Amputation
Incision
Perform a fish-mouth incision and create symmetrical anterior and posterior flaps. The medial and lateral apexes of the incision should be distal to the level of planned osteotomy (Figure 39.3).
For amputations proximal to the middle of the humerus, preserve as much bone length as possible.
For distal above-elbow amputation, preserve part of the humerus condyles to create a solid bone base for interaction with the prosthesis. If condyles cannot be spared, remove at least 4 cm of the distal humerus to facilitate prosthesis fitting with an elbow-lock mechanism, resulting in equal length of the contralateral arm.
