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Think reverse arthroplasty for certain fractures
Reverse shoulder prosthesis is indicated for treatment of select proximal humerus fractures.
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Proximal humerus fractures can be some of the most challenging fractures that we fix in orthopedics. The rotator cuff surrounds the articular fragment and precludes our view of the joint. Therefore, reduction is performed indirectly under fluoroscopic visualization. Bone quality, fracture configuration, and patient characteristics heavily influence treatment of proximal humerus fractures. The goal is to reconstruct and recreate normal anatomy. Many fractures are not amenable to fixation, and these fractures are treated with replacement arthroplasty of some type.
The results of hemiarthroplasty for fracture have historically been dependent on tuberosity healing because rotator cuff function is so important for normal shoulder motion. If tuberosities heal in anatomic location, a good functional result can be anticipated. Tuberosities are susceptible to migration and reabsorption, even after anatomic reduction during surgery. An overly aggressive rehabilitation program can also compromise tuberosity healing.
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Age-appropriate treatment
Fractures that have significant comminution of the metaphyseal region or extension into the proximal shaft are difficult to reconstruct. The metaphyseal region provides support for the humeral head during open reduction internal fixation. This is a fracture that should be treated with ORIF in a younger patient, but may be appropriate for arthroplasty in an older individual. The metaphyseal comminution provides a challenge during arthroplasty as well because the tuberosities must heal to the shaft. The comminution may result in a gap between the tuberosities and the shaft, predisposing it to failure of tuberosity healing.
Failure of tuberosity healing is associated with a poor functional result and a painful shoulder after hemiarthroplasty. This condition is associated with proximal migration of the humeral head, iatrogenic anterior, superior instability, and stiffness. A failed or painful hemiarthroplasty is a very, very challenging problem and failure of a hemiarthroplasty for fracture is one of the most common indications for a reverse shoulder arthroplasty.
The results of hemiarthroplasty for fracture are very interesting. Postoperative elevation averages about 90° to 110°. But if you look carefully at these results, they are usually two groups. There is one group that gets 150°, 160° — and the remainder of the patients has minimal elevation (essentially a shoulder shrug) and the average is about 90°. In other words, either the tuberosities heal and the result is good, or they don’t and the results are poor. This is important to consider when interpreting the results.
A better option
Therefore, with a patient in whom tuberosity healing may be compromised because of age, biology or fracture characteristics, is there a better option than standard hemiarthroplasty? A reverse shoulder arthroplasty offers immediate stability, patients can begin early rehabilitation, and the results are not as dependents on tuberosity healing. Importantly, a reverse arthroplasty does not mean “throw the head and tuberosities in the bucket.” Tuberosity repair is still recommended and is an important part of the procedure. The difference is that a cuff-deficient hemiarthroplasty is likely to lead to a poorer result than a cuff-deficient reverse arthroplasty. Functional results of a reverse shoulder arthroplasty are better if there is enough posterior cuff function to maintain some external rotation.
Indications for a reverse arthroplasty for fracture are not definitively established in the literature. Basically, my indications are: age — greater than 70 years, a fracture associated with severe tuberosity comminution, and a shoulder with a pre-existing rotator cuff tear.
We also use a reverse for fracture sequela, specifically nonunion, malunion, AVN in older patients with compromised rotator cuff function.
Tuberosity repair, with a reverse is important. The purpose of trying to get tuberosities to heal is to try to restore some teres minor/infraspinatus function. This will improve the functional result by maintaining some external rotation. This will hopefully prevent the arm from falling into obligate internal rotation with elevation and will increase both strength and range of motion in the shoulder. I typically fix the tuberosities with 18 gauge wires or heavy suture. At this time, there are few published results of reverse shoulder arthroplasty for fracture. In the proceedings of the Nice course there were 15 patients identified, 11 with a 2-year follow-up. The age-adjusted Constant score was 81%. Elevation was 107° and external rotation was 10°. In these 11 patients, the results were not dependent on tuberosity healing.
High complication rate
The complication rate is relatively high with reverse shoulder arthroplasty, and may be higher in inexperienced hands. Complications include: dislocation, loosening, scapular notching, tuberosity, migration.
Overall, results of hemiarthroplasty and reverse are similar if the tuberosities heal. But tuberosity healing is difficult and failed healing is the major cause of compromised results after hemiarthroplasty. Hemiarthroplasty results in two disparate groups — some patients obtain 160° of elevation, and many of them get poor elevation. So, a reverse seems to find a middle ground and offer good stabilization in an immediate setting.
I do not think that a reverse should replace a hemiarthroplasty at this point. But, I think that it does have a place in fracture treatment. I think it has a place where there is high risk for poor results. Indications include a comminuted metaphysis, comminuted tuberosities, age over 70 and pre-existing rotator cuff disease.
For more information
- Leesa M. Galatz, MD, can be reached at Washington University Orthopedics, One Barnes-Jewish Hospital Plaza, Suite 11300 ,West Pavilion, Saint Louis, MO 63110; 314-747-2813; e-mail: galatzl@wudosis.wustl.edu.
Reference:
- Galatz LM. Reverse shoulder replacement: Forward thinking in acute fx—Affirms. Paper#5. Current Concepts in Joint Replacement Spring 2007. May 21, 2007. Las Vegas.