Shoulder arthroplasty is technically challenging and continues to rely heavily on precise surgical technique. This procedure is reserved for patients with painful degenerative glenohumeral joints. Successful glenoid resurfacing with durability and longevity depends on sufficient glenoid exposure. Coordinated soft tissue and osseous management is the mainstay of adequate glenoid exposure. Special considerations for subscapularis management, capsular releases, and osseous excisions are presented.
Glenohumeral arthroplasty is reserved for painful and symptomatic arthropathy.
Arthroplasty is contraindicated in patients with an active joint infection, who are noncompliant, and who are asymptomatic.
Preserve the deltoid origin.
Protect the musculocutaneous and axillary nerves at all times.
Visualize the rotator cuff origin.
Meticulous attention to soft tissue and osseous management allows for superior glenoid preparation.
Inadequate releases of the inferior and posterior capsule leads to compromised glenoid exposure.
Release the rotator interval superiorly.
This allows for visualization of the rotator cuff insertion and hence proper osteotomy.
Release the inferior capsule off the humeral metaphyseal neck region and continue posteriorly.
If release is initially inadequate, continue after humeral head osteotomy is done.
In 1971, the first nonconstrained glenohumeral prosthesis with a polyethylene glenoid component was introduced to the United States. It has been established as an effective procedure in the treatment of degenerative, inflammatory, and posttraumatic arthropathy of the glenohumeral joint. Pain relief and improved motion have been demonstrated in multiple patient series. Since its initial introduction, total shoulder prosthetic replacement surgery has evolved through a variety of implant designs. These changes have included variations in humeral head sizes and stem lengths, modularity of components, and glenoid replacements with differing design philosophies. Most implant variations have shared the nonconstrained design, which allowed for rehabilitation of the shoulder without mechanical blocks to motion. However, satisfactory pain relief, nonconstrained motion, and implant longevity continue to rely heavily on precise intraoperative soft tissue management and proper placement of components.
Total shoulder replacement surgery is considered one of the most technically demanding of current joint arthroplasty procedures. Restoration of shoulder anatomy and biomechanics is the fundamental goal of total shoulder replacement. Proper glenoid component positioning plays a critical role in the success of glenohumeral arthroplasty. Glenoid malpositioning can often lead to humeral instability and early loosening from increased stress on the glenoid component. Meticulous technique and adequate glenoid exposure can assist a surgeon to effectively resurface the glenoid in a proper manner to increase longevity, improve clinical outcomes, and avoid the pitfalls of a malpositioned glenoid prosthesis.
Certain patient populations may not be ideal candidates for glenoid prosthetic replacement, even in the presence of symptomatic glenoid arthropathy. Fortunately, new techniques for glenoid resurfacing are being developed that obviate the need for a prosthetic glenoid implant. In those instances, glenoid component positioning is not a concern, but sufficient glenoid exposure is still required for placement of interpositional material or instrumentation needed in nonprosthetic resurfacing.
Symptomatic glenohumeral arthropathy is a challenging problem. Often patients present with pain and stiffness unresponsive to conservative measures. Physical therapy may be effective in individuals with stiffness and tolerable pain levels, but rarely effective alone for the painful and stiff patients. In some conditions, it may be reasonable to consider glenohumeral injections, but it is unlikely to offer long-term relief of arthritic pain. In other instances of early arthritis, arthroscopic joint debridement and removal of loose bodies with or without joint releases may offer a reasonable solution for pain relief and stiffness but is seldom effective for late arthritic conditions.
Shoulder arthroplasty with glenoid resurfacing should be considered in patients with glenohumeral arthropathy who have adequate glenoid bone stock, an adequate and functional rotator cuff, and proper age and disease criteria. Proper glenoid visualization and accessibility are critical to correct glenoid management. Therefore, the need for adequate soft issue releases and glenoid exposure is indicated in those cases in which glenoid resurfacing is required.
Achieving proper glenoid exposure for resurfacing can be challenging and frustrating. It is composed of a delicate balance of arm and retractor positioning coordinated with soft tissue and osseous management. The major components of the surgical anatomy that affect adequate glenoid exposure are the soft tissues (subscapularis, joint capsule, labrum, and adhesion tissue) and the osseous structures (humeral head, humeral metaphysic, osteophytes, and the glenoid itself). These key soft tissue and bony structures need to be addressed accordingly during the operation to effectively gain access to the glenoid for resurfacing. Additionally, the presence of the axillary nerve needs to be recognized and protected at all times during surgical releases, especially during subscapularis tenotomy, joint capsulectomy, and blunt retraction.
Glenohumeral arthroplasty with glenoid resurfacing should be reserved for only the symptomatic patient with intact rotator cuff and deltoid muscles, sufficient glenoid bone stock, and reasonable functional goals. Arthroplasty is unwarranted in individuals with insufficient symptoms to limit their functional capacity and quality of life. All reasonable conservative and nonoperative management options should be attempted for this population.
Glenoid resurfacing is contraindicated in patients with both rotator cuff and deltoid deficiency. Their inability to reproduce normal glenohumeral biomechanics has significant consequences on glenoid component longevity and outcome. However, soft tissue procedures and/or muscle transfers can be performed for either cuff or deltoid deficiency alone, and their isolated dysfunction is not necessarily an absolute contraindication to arthroplasty. Glenohumeral prosthetic replacement for specific soft tissue-deficient conditions will be addressed in later chapters.
Inadequate glenoid bone stock can be an unfortunate sequelae of degenerative diseases, inflammatory diseases, or trauma. The lack of a satisfactory osseous glenoid platform without prior bone grafting is a contraindication for placement of a glenoid component. Additionally, the presence of a glenohumeral joint infection is an absolute contraindication to glenoid replacement and arthroplasty in general. Joint infections should be managed with proper surgical joint debridement and antibiotic protocols. Only after definitive infection control and confirmation with negative cultures should prosthetic replacement be readdressed.
Lastly, arthroplasty should not be performed in patients who are incapable or unwilling to participate in postoperative protocols. Physical therapy and adherence to postoperative instructions contribute to the success of any joint arthroplasty operation. Patient noncompliance and the inability to adhere to postoperative instructions are considered a relative contraindication. Therefore, this population should be considered candidates for nonoperative management.
SURGICAL TECHNIQUE PREOPERATIVE EVALUATION
A thorough history and physical examination should be obtained prior to operative consideration. Any history of previous trauma to the shoulder needs to be investigated. In addition, all documentation from previous surgeries in the involved shoulder should be thoroughly scrutinized, especially for information pertaining to the status of the soft tissues and osseous defects at the time of prior procedures. On physical examination, discrepancies between active and passive ranges of motion may assist in the diagnosis of muscular deficiencies. The presence of crepitus with shoulder range of motion can suggest glenohumeral arthritis.
A complete neurologic examination should be performed during the time of examination. Any nerve deficits should be investigated, especially in cases in which the axillary nerve function is in question. In the presence of an uncertain neurologic examination, electromyographic studies can be employed to help rule out nerve injury.
Radiographic imaging provides important information on the condition of the glenohumeral joint during preoperative evaluation. The axillary shoulder view is useful in evaluating the glenoid for posterior glenoid wear, often seen in glenohumeral arthritis, and for sufficient glenoid bone stock to accommodate resurfacing ( Fig. 9–1 ). Computed tomographic (CT) studies should be obtained when the glenoid is ill defined on plain radiographs or when more information is required for preoperative planning. CT scans provide valuable three-dimensional imaging of osseous structures to assist in the proper decision making for glenoid resurfacing.