Shoulder Hemiarthroplasty Technique

Deltopectoral approach

The deltopectoral approach ^{[10, 44]} is the most commonly used approach for shoulder arthroplasty. It provides excellent humeral exposure and preserves the deltoid origin, making it an ideal approach for hemiarthroplasty. The approach begins with identification of the coracoid process.

A 10- to 15-cm incision is made from the distal tip of the coracoid process towards the deltoid insertion on the humerus. The cephalic vein is identified and dissected free of its pectoral attachment. The internervous plane is developed by retracting the deltoid and cephalic vein laterally and the pectoralis major medially. The fibrous clavipectoral fascia is incised longitudinally, lateral to the conjoint tendon of the short head of the biceps and the coracobrachialis.

If adequate exposure is not attainable with medial retraction of the conjoint tendon, the coracoid may be osteotomized prior to medial retraction and later reduced. Keeping the arm adducted during this step reduces risk of injury to the axillary sheath. Avoiding excessive retraction of the conjoint tendon minimizes risk of musculocutaneous nerve neuropraxia.

The subscapularis is identified deep to the conjoint tendon. Three small vessels delineate the inferior border of the subscapularis. These vessels are identified and ligated. Just inferior, the axillary nerve may be palpated as it courses through the quadrangular space.

External rotation of the arm moves the musculotendinous junction of the subscapularis away from the axillary nerve. The subscapularis is tagged with sutures, then divided approximately 2 cm from its lesser tuberosity attachment, near the musculotendinous junction.

The joint capsule is now visible and can be sharply incised longitudinally to afford access to the glenohumeral joint.

Humeral head replacement

The arm is externally rotated, adducted, and extended to dislocate the humeral head. The humeral head is then templated and resected with the elbow flexed to 90º and with approximately 30º of external rotation. Before resection of the humeral head, a large Homan retractor can be placed under the biceps tendon to protect the long head of the biceps tendon and the rotator cuff during resection.

The arm is then manipulated to bring the cancellous surface of the humerus into clear view. The humeral canal is then reamed with progressively larger reamers until satisfactory cortical purchase is attained. Overzealous reaming should be avoided to minimize the risk of intraoperative fracture. A body-sizing osteotome is then inserted into the reamed canal and tapped with a mallet. The tracks created will be used to accept the trial implant.

Next, align the trial stem with the tracks created by the template and insert it into the intramedullary canal. The trial head can then be placed on the trial stem. The head must lie flush with the humeral cuts. If it is not flush, more bone can be removed with the bone saw to obtain an ideal fit. The shoulder is then reduced to test flexion, extension, abduction, adduction, and stability.

Remove the acceptable trial, and assemble the final implant. The final implant is then inserted, with the template grooves used as a guide. The shoulder is then reduced, and range of motion (ROM) can be rechecked to ensure that no impingement is present. The joint is then thoroughly irrigated.

Closure

Under neutral rotation, the subscapularis is repaired. The deltopectoral interval is then closed with interrupted absorbable sutures. The subcutaneous layer is approximated with interrupted absorbable sutures. Finally, the skin can be closed with absorbable running subcuticular sutures.

Pain management

A pain medication (eg, oxycodone) is prescribed at the surgeon’s discretion, depending the patient's level of pain 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.

The initial goal of postoperative rehabilitation is to maximize passive ROM while allowing the reattached subscapularis to heal. Passive ROM exercises are started on the first day after surgery.

At the first postoperative follow-up visit (usually 10-14 days after surgery), the patient is given a prescription for physical therapy focusing on developing passive ROM. The physical therapist should also educate the patient regarding home exercises for the first 6 weeks.

Active ROM is encouraged and advanced as tolerated after the initial 6-week interval. With good passive ROM, strengthening of the deltoid, rotator cuff, and scapular stabilizers is instituted. Patients should progress as tolerated with active ROM and strengthening over the 6- to 12-week interval.

Over the 12- to 24-week interval, strengthening exercises continue, and the patient should be returning to normal activities of daily living. Continued strengthening exercises beyond the 24-week interval are recommended. Although most improvement will be seen over the first 24 weeks, functional improvement may continue to be seen for up to 1 year.

The postoperative rehabilitation approach implemented by Dr Warner at the Boston Shoulder Institute comprises four phases, as follows:

• Phase I - The patient will remain in a shoulder immobilizer for 4 weeks; during this time, pendulum exercises will be permitted, and passive ROM will be begun by the therapist formally on return at 1 week; the only limit to passive motion will be external rotation to 40º
• Phase II - At 4 weeks, the sling will be removed so that the patient can use the arm for daily living activities, including washing, dressing, and driving; self-assisted stretching will supplement the stretching done by the therapist
• Phase III - At 8 weeks, therapy will consist of progressive strengthening
• Phase IV - At 16 weeks, the patient will be allowed to exercise skilled sports

Progressive glenoid arthrosis

Progressive degeneration of the glenoid cartilage subsequent to hemiarthroplasty remains one of the most frequent complications seen after hemiarthroplasty. Younger patients placing higher demand on their shoulder are predictably at risk. Wear of the glenoid cartilage following hemiarthroplasty correlates with a poorer Constant score ^[45] and may necessitate conversion to total shoulder arthroplasty (TSA).

Instability

Instability following hemiarthroplasty is one of the relatively more common postoperative complications. Damage or dysfunction of any passive or active shoulder stabilizers can lead to instability. A thorough evaluation of the joint is paramount for determining the underlying cause of instability. Etiologies include component malposition, deltoid dysfunction, inadequate subscapularis repair or rupture, and soft-tissue imbalance. ^[38]

Infection

Infection is a relatively uncommon but potentially devastating complication of hemiarthroplasty. ^{[38, 46]} Dr Warner has observed a 0.24% rate of infection after hemiarthroplasty over the course of 1 year (Warner JJP, personal communication, 2018). Arthroscopic tissue culture appears to be more reliable than fluoroscopically guided aspiration for determining whether a patient has a shoulder infection. ^[47]

Preoperative and postoperative antibiotic coverage targeting gram-positive cocci and Propionibacterium species is standard. Depending on the severity of infection, treatment can range from thorough irrigation and debridement with subsequent intravenous antibiotics to component removal. Patients may require lifelong antibiotic prophylaxis before undergoing any invasive procedure that may lead to bacteremia (eg, dental work).

Aseptic loosening

Although radiolucency at the bone-cement interface is not uncommon, progression and clinical symptoms necessitating revision surgery are rare. ^[34]

Nerve and muscle dysfunction

Preserving deltoid function is a critical portion of hemiarthroplasty. Deltoid dysfunction, caused either by axillary nerve injury or by deltoid dehiscence, results in loss of function and pain. Dr Warner has observed a 0.71% rate of nerve injury after hemiarthroplasty over the course of 1 year (Warner JJP, personal communication, 2018). 

Heterotopic ossification

Heterotopic ossification is more common in the shoulder treated with hemiarthroplasty for humeral fracture. Severely injured soft tissues during the initial trauma and delayed surgical intervention are associated with higher rates of heterotopic ossification, though it typically is not clinically significant.

Hypotension

YaDeau et al found that hypotension occurred frequently during shoulder arthroscopy performed in the sitting position with regional anesthesia; however, cerebral oximetry desaturation was uncommon. ^[48]

Use of an antihypertensive medication preoperatively has been shown to increase the incidence of intraoperative hypotension during shoulder arthroscopy performed in the sitting position. ^[49] To maintain normal blood pressure, these patients are expected to require vasopressors more often.

Nonunion and malunion

In the setting of hemiarthroplasty for fracture, the risk of fracture nonunion or malunion is increased, particularly in those with poor bone quality. Boileau et al found that as many as 50% of shoulders reconstructed with hemiarthroplasty following displaced fractures demonstrated tuberosity malposition, which correlated with unsatisfactory result, stiffness or weakness, and pain. ^[50]

With osteotomy of the greater tuberosity, outcomes have been found to be poor and unpredictable. ^[51] Revision surgery with bone grafting may be necessary for proper fracture healing. In the setting of greater tuberosity resorption, conversion to a reverse total shoulder prosthesis may provide some improvement. ^[48]

Periprosthetic fracture

Postoperative periprosthetic fracture is more common in the elderly and osteoporotic. 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.

Persistent pain

Identifying the cause of persistent pain following hemiarthroplasty is the most important step in determining future treatment. In many cases, the cause of persistent pain may be due to one of the aforementioned complications. Once the surgeon determines the appropriate cause, either surgical or nonsurgical interventions may be undertaken to improve both pain and quality of life.

In cases of failed hemiarthroplasty, several therapeutic options are available, including conservative treatment, arthroscopic debridement, PROSTALAC (prosthesis of antibiotic-loaded acrylic cement), resection arthroplasty, revision hemiarthroplasty with bony and/or soft-tissue reconstruction, shoulder arthrodesis, and revision to a reverse shoulder arthroplasty (RSA), which has been described by Parnes et al. ^[52]

Reverse shoulder arthroplasty

Levy et al reported on 19 failed shoulder hemiarthroplasties with rotator cuff arthropathy. ^[53] After revision to a reverse prosthesis, patients were found to have significant improvements in forward flexion and abduction, American Shoulder and Elbow Surgeons (ASES) shoulder score, and Visual Analogue Scale (VAS) score for pain, which indicated satisfactory results of the RSA for salvage after failed hemiarthroplasty.

Prosthesis of antibiotic-loaded acrylic cement

Patients presented with infection after hemiarthroplasty may be considered for PROSTALAC insertion. Jawa et al reported a series of 28 patients who underwent PROSTALAC insertion for treatment of an infection after shoulder arthroplasty. ^[54] Infection was initially eradicated in 82% of the patient cohort, demonstrating that PROSTALAC for the treatment of infection following shoulder arthroplasty is beneficial.

Resection arthroplasty

When revision arthroplasty is not feasible, resection arthroplasty has been used as a salvage option to restore function and relieve pain. In a retrospective review of 26 patients who underwent resection arthroplasty, Muh et al demonstrated a significant improvement in VAS scores and moderate decreases in active forward flexion and external rotation. ^[55]