Thermal Shrinkage

Overview
Reviewed by Dr. Jon Warner

The end of the shoulder blade, or scapula, that creates the shoulder socket is known as the glenoid. It is surrounded by a small, flexible tissue known as the labrum, which acts as a seal to make a tighter fit between the glenoid and the head of the humerus, or upper-arm bone. A group of four muscles and their respective tendons, known as the rotator cuff, stretches from the humerus to the glenoid and serves two purposes. First, the rotator cuff helps to raise, lower, and swing the arm, giving the shoulder a large range of motion. Secondly, the cuff serves to keep the humerus inside the glenoid socket. The cuff is covered by a pack of tight ligaments, known as the capsule, that attaches the humerus to the glenoid.

Repeated dislocation or subluxation of the humerus out of the glenoid is known as instability. Instability is a weakening of the capsule of the shoulder joint, which allows the arm bone to slip out of the shoulder socket, causing pain, frustration and loss of faith in the shoulder as a sturdy joint. Instability is often accompanied by a tear of the labrum or rotator cuff, a Bankart lesion or a Hill-Sachs defect. A process known as stabilization can remedy chronic instability, and it may be done one of two ways: arthroscopically or open. Thermal shrinkage is a new component of arthroscopic stabilization in which heat is applied to the capsule to tighten the ligaments within it.

Detailed Description
Specialist
Orthopedic surgeon

Procedure

Before the procedure:
The patient's medical history and any possible allergies to medication are determined. The surgeon may order X-Rays, an MRI [link], CT Scan [link] or EMG [link] to look into the joint before the procedure. The patient is dressed in a hospital gown and anesthetized either locally or generally.
During the procedure:

A number of half-inch incisions will be made to allow the arthroscope to enter the shoulder joint. A sterile saline solution will be pumped into the joint both to cleanse it and to expand it for better visualization. The surgical staff may also pump air into the joint to create more room to see inside the joint. While watching a monitor that shows a magnified image of the inside of the shoulder, the surgeon performs a number of procedures within the joint (see stabilization for a full report). While inside the joint, he or she inserts a thermal probe into an arthroscopic portal. The probe then heats the parts of the capsule and shrinks them to eliminate unnecessary joint laxity.

Recovery
Directly following the procedure, the surgeon may order the patient to use a Continuous Passive Motion machine to prevent atrophy and stiffness within the shoulder joint. Cryotherapy, the therapeutic use of hot and cold to reduce comfort, may be administered. Once discharged from the hospital, the patient will likely undergo a demanding strengthening regimen to further tighten the rotator cuff muscles. Rehabilitation will continue for six to nine months for most patients with acute dislocations, with full range of motion returning after about three months.

Complications/Risks

• Neurovascular injury
  
• Damage to axial nerve, which comes out of neck through axilla (armpit)
  
• Chance that ligaments will weaken again
  
• Because it is a relatively new procedure, limited information is available on the results of thermal shrinkage on shoulder instability. Tissue may stretch again, requiring further shrinkage or even an open surgical procedure. This surgery has been performed on many shoulders with short-term success but unknown long-term success.