Q: Surgical intervention for end-stage osteoarthritis (OA) of the shoulder remains controversial. What are indications for surgical intervention?
A: The most common shoulder conditions treated with total shoulder replacement (TSR) are primary degenerative arthritis, inflammatory arthritis, osteonecrosis, post-traumatic arthritis and arthritis following instability procedures with degenerative OA accounting for approximately 60%. Patients with pain, who have failed nonoperative treatment, have ability to comply with postoperative rehabilitation, and who are at acceptable surgical risk are indicated for surgery.
Surgical candidates typically have a pain severity that is nonresponsive to NSAIDs, affects all their daily and routine activities, and does not allow them to sleep. Anatomical factors also greatly influence surgical indications. Total shoulder replacement with glenoid resurfacing requires a functioning rotator cuff, functioning deltoid, and adequate glenoid bone stock to support the glenoid component. Rotator cuff dysfunction allows superior migration of the humeral head that causes eccentric loading of the glenoid component and early loosening. Similarly, a dysfunctional deltoid can result in instability of the humeral component relative to the glenoid component leading to glenoid loosening. Glenoid loosening may also occur if the glenoid bone stock is not capable of supporting the periphery of the component or the keel or pegs of the implant within the glenoid vault.
Q: Is there an indication for humeral head replacement, when both sides of the joint are extensively involved?
Several situations favor humeral head replacement without glenoid prosthetic resurfacing, even when both the glenoid and the humeral head have extensive arthritic changes. These include rotator cuff deficiency, glenoid bone deficiency, and also young, highly active patients. Patients with rotator cuff deficiency risk glenoid component loosening. The cause of loosening is eccentric loading of the glenoid from proximal migration of the humerus. Patients who have ability to raise their arm despite rotator cuff deficiency are treated with a hemiarthroplasty and glenoid reaming to correct version abnormalities but without resurfacing the glenoid. Older patients, eg 80 years old or older, with advanced degenerative changes of the glenohumeral joint, proximal humerus migration, and inability to raise their arm which are characteristics of rotator cuff arthropathy, are indicated for reverse shoulder arthroplasty.
Patients with severe glenoid erosion may not have enough bone stock to support a glenoid component (Figure 1). This can be observed in the setting of OA with severe posterior glenoid wear patterns. Rheumatoid arthritis can result in severe central erosion and limit ability to resurface the glenoid. Revision arthroplasty that requires glenoid removal for a loose glenoid component or infected component can result in deficient bone stock and prohibit revision glenoid implantation.
Standard radiographs must be used to assess degree of both glenoid arthrosis and glenoid wear pattern. The AP radiograph should assess humeral head position with superior migration indicating rotator cuff dysfunction or medialization indicating decreased glenoid vault volume. An axillary view is necessary to assess glenoid vault volume, extent of posterior glenoid wear, and alterations in glenoid version. We now routinely obtain a CT scan in all patients to adequately assess glenoid bone stock. MRI adds additional information on the integrity of the rotator cuff.
Young patients with extensive degenerative arthritis are at risk for glenoid component loosening, particularly if they cannot modify their postsurgical activities and are involved in heavy use of their upper extremities. These patients may be better treated with hemiarthroplasty with concentric reaming of the glenoid. In addition, non-stemmed components to preserve bone stock on the humerus may be beneficial since future revision is anticipated (Figure 2).
Q: What about the OR time, blood loss, learning curve, complication rates between total replacement and humeral head replacement?
A: Many surgeons criticize TSR when compared to simple hemiarthroplasty because of the associated increase in surgical time, blood loss, technical difficulty, and fear of eventual glenoid component loosening. In 2000 a study was performed a prospective randomized study that included 47 patients with 51 shoulders who were randomized to either TSR or hemiarthroplasty. TSR provided superior pain relief but was associated with increased cost, operative time (35 minutes), and blood loss (150 mL) per patient when compared with hemiarthroplasty. None of the total shoulder arthroplasties required revision in contrast to three of the 25 patients who required revision surgery to resurface the glenoid in the hemiarthroplasty group.
The concern for glenoid component loosening in TSR remains despite improvements in implantation technique and prosthetic design.
Another systematic review in 2007 found that only 80 of 1,238 TSRs (6.5%) required revision surgery for any cause. TSRs that used metal-backed glenoids required revision in 6.8% of cases. However, the revision rate for loosening of all-polyethylene glenoids was only 1.7%. Meanwhile, 8.1% of hemiarthroplasties required conversion to TSR because of persistent pain.
As in other surgical procedures, increased surgeon volume is associated with improved outcomes for TSR. Patients of the surgeons who performed an average of less than two shoulder arthroplasties during a 7-year study period had inferior outcomes compared to higher volume surgeons, according to Hammond and colleagues in 2003. In addition, patients treated by high-volume surgeons had fewer complications and shorter lengths of stay.
Q: What are some critical points in the preoperative establishment of an intact rotator cuff?
A: Evaluation of rotator cuff integrity is a requisite for total shoulder replacement. History, physical examination, X-rays, and advanced imaging provide the necessary information.
Patients with .massive rotator cuff tears may give a history of inability to raise their arm or simple weakness to forward elevation in addition to pain. Physical exam maneuvers that suggest an irreparable rotator cuff tear include poor active forward elevation or external rotation with preserved passive range of motion. External rotation lag sign and the horn blower’s sign also indicate massive rotator cuff tears. The lift-off test, belly press, and internal rotation lag sign indicate compromised subscapularis function. X-rays may reveal proximal humerus migration indicating a rotator cuff tear.
Finally, MRI scan can give details of the rotator cuff including tear size, degree of retraction, muscle atrophy, and fat infiltration. Any patient with history, physical, or X-rays suggestive of a rotator cuff tear undergoes an MRI scan prior to surgery.
This is an excerpt from a recent online ortho journal as referenced above. It is an excellent summary of my own approach to treating osteoarthritis of the shoulder.
- Gartsman, GM, Roddey TS, Hammerman SM. Shoulder arthroplasty with or without resurfacing of the glenoid in patients who have osteoarthritis. J Bone Joint Surg (Am). 2000;82(1):26-34.
- Hammond, JW, Queale WS, Kim TK, McFarland EG. Surgeon experience and clinical and economic outcomes for shoulder arthroplasty. J Bone Joint Surg (Am). 2003;85-A(12):2318-2324.
- Radnay CS, Setter KJ, Chambers L, Levine WN, et al. Total shoulder replacement compared with humeral head replacement for the treatment of primary glenohumeral osteoarthritis: a systematic review. J Shoulder Elbow Surg. 2007;16(4):396-402.