Shoulder Replacement Surgery is also known as a Hemi shoulder arthroplasty. It is a shoulder replacement surgery in which the arm bone is replaced with a prosthetic metal implant, and the remaining half of the shoulder joint, called the glenoid, is left intact.
Types of Shoulder Replacement Surgery
There are two types of hemiarthroplasties:
Stemmed Hemi shoulder arthroplasty: This procedure replaces the head of the humerus with a metal ball and stem, which is similar to the component used in a total shoulder replacement. It is advised when -
The head of the humeral bone is severely fractured or arthritic, but the socket is normal.
In patients with large rotator cuff tear.
Resurfacing Hemi shoulder arthroplasty: It involves replacing the joint surface of the humeral head with a cap-like prosthesis and no stem. This procedure preserves bone and prevents the risk of component wear and loosening.
When is Shoulder Replacement Surgery needed?
Shoulder replacement surgery is advised to patients with severe, persistent conditions of shoulder osteoarthritis in which only the humeral head is damaged. If the shoulder pain limits routine activities and all non-surgical methods of treatment have failed, including anti-inflammatory medications, cortisone injections, and physical therapy, then shoulder replacement surgery should be considered.
A shoulder replacement surgery alleviates pain, improves motion, strength and function. However, the way a shoulder replacement ultimately performs depends upon numerous factors such as the patient's activity level, age, and overall health. An orthopaedic surgeon must thoroughly screen each patient to determine the most appropriate type of shoulder replacement.
The general indications for patients who are eligible for hemi shoulder arthroplasty include the following:
Pain due to glenohumeral osteoarthritis that has failed conservative therapy with sparring of the glenoid articular surface
Patients with primary arthritis where rotor cuff is deficient
Glenohumeral arthritis with inadequate glenoid bone stock
Patients at risk for glenoid component loosening, especially younger patients and those requiring heavy usage of their shoulder, are ideal candidates for surgery.
Acute fracture indications for hemi shoulder arthroplasty are:
Near four-part fractures
Near three-part fractures when the poor quality of bone compromises open reduction and internal fixation
Near three- and four-part fractures with concomitant dislocation of the humeral head.
Who Should Not Consider Shoulder Replacement Surgery?
Absolute contraindications for Shoulder Replacement Surgery are:
Patients with an existing infection
Patients who are not motivated for surgery.
Coraco-acromial ligament deficiency
Previous glenohumeral arthrodesis
Incongruent glenoid and humeral surfaces
Severe loss of glenoid articular cartilage
Fracture treatable with ORIF
Nondisplaced fractures treatable nonoperatively
Relative contraindications are:
Poor overall health of the surgical candidate
Unrealistic patient expectations
Diagnosis Before Shoulder Replacement Surgery
True (Grashey) AP of the shoulder are taken 30-40 degrees oblique to the coronal plane of the body to determine the extent of DJD and delineation of fracture pattern
An axillary view is taken to look for posterior wear of the glenoid, and it also helps quantify displacement in cases of fracture.
This is done to determine the glenoid version and glenoid bone stock.
It is also useful if the fracture pattern is poorly represented after radiographic evaluation.
It helps evaluate the rotor cuff.
During Shoulder Replacement Surgery (Hemi shoulder arthroplasty) Procedure
Patients are anaesthetized to provide excellent pain control in the immediate postoperative period and permit the minimization of general anaesthetic during the procedure. The anesthesiologist administers general anaesthesia for the entire duration of the surgical procedure.
Positioning of the Patient
The patient is asked to lie in the modified beach-chair/semi-Fowler position with knees flexed. A McConnell headrest allows proper positioning with the patient toward the top portion of the table and the affected shoulder's arm hanging off the table edge nearest the primary surgeon. The entire arm should then be draped and prepped in a meticulous sterile fashion.
Incisions are made, and the joint is operated upon.
The skin is finally closed with absorbable sutures.
Pain medication is prescribed at the surgeon's discretion, depending on the patient's pain level and ability to tolerate it. It is suggested that the process of weaning the patient from the pain medication should begin a few days after the operation.
Preparation for Shoulder Replacement Surgery
Preoperative laboratory tests are ordered based on the patient's age and medical history. Tests are ordered for all patients older than 50 years, such as:
Complete blood count test
Specialists counsel patients with a medical history to obtain medical clearance in advance of surgery.
Possible Complications After Shoulder Replacement Surgery
Most surgeries have risks and complications. Hemi shoulder arthroplasty has the following possible complications:
Progressive Glenoid Arthrosis
The progressive degeneration of the glenoid cartilage subsequent to hemi shoulder arthroplasty happens most frequently. Younger patients placing higher pressure on their shoulders are at risk.
Instability after a hemi shoulder arthroplasty procedure is one of the relatively more common postoperative complications. The damage or dysfunction of any passive or active shoulder stabilizers leads to instability. Etiologies include component malposition, deltoid dysfunction, inadequate subscapularis repair or rupture, and soft-tissue imbalance.
An active infection is an uncommon complication, but potentially devastating.
Although radiolucency at the bone-cement interface is rare, progression and clinical symptoms necessitating revision surgery are rare.
Nerve and muscle dysfunction
Preserving deltoid function is a critical part of hemi shoulder arthroplasty. Deltoid dysfunction, caused either by axillary nerve injury or deltoid dehiscence, results in loss of function and pain.
Severely injured soft tissues during the initial trauma and delayed surgical intervention are associated with higher rates of heterotopic ossification.
Hypotension may occur in patients who have undergone hemi shoulder arthroplasty and may need to take vasopressors to control it.
Non-union and malunion
When hemi shoulder arthroplasty is being carried out for treating fractures, there's always a risk of fracture non-union or malunion. It is specifically an issue when the bone quality is poor.
Postoperative periprosthetic fracture is common in the elderly and those with osteoporosis. It frequently occurs as the result of trauma from falls. Stable fractures may be treated nonoperatively. However, surgical intervention is warranted with any unstable periprosthetic fracture.
Sometimes, pain may not subside for a long time. The surgeon needs to determine the appropriate cause and suggests either surgical or non-surgical intervention to improve pain and quality of life.
Care After Shoulder Replacement Surgery
A well-planned rehabilitation program is critical to the success of a hemi shoulder arthroplasty.
Most patients are required to wear a sling for three to four weeks.
Gentle physiotherapy begins immediately following surgery to restore range of motion and progress to include exercises that strengthen the shoulder joint.
Total rehabilitation may take several months, but specific recovery time varies by patient and demand, as with all surgical procedures.