Premium Wordpress Themes by UFO Themes
Arthroplasty in the Neurologically Impaired Shoulder
Alexander R. Graf, MD
Steven I. Grindel, MD
A painless functional shoulder is contingent upon not only the integrity of the articular cartilage but also the strength of the rotator cuff and surrounding musculature that animate the shoulder girdle. Both central and peripheral nervous system disorders can compromise shoulder stability and function through secondary problems such as overload, weakness, spasticity, contracture, and aberrant movement patterns. These problems present unique challenges to shoulder arthroplasty and require a thorough understanding of how glenohumeral anatomy, kinematics, muscle tone, and postoperative demands differ from that of the “normal” shoulder to optimize outcomes (TABLE 47.1)
. In addition, recognition of the unique psychosocial demands of this population cannot be overstated. While previous studies have shown increased complications following shoulder arthroplasty in patients with neurologically impaired shoulders, the tremendous improvements on quality of life that can result make treating this vulnerable patient population especially worthwhile.
Understanding the patient’s current level of functioning, independence, pain level, and their goals of surgery are all important elements in caring for this complex patient population. It is our experience that these patients often delay surgical intervention until the shoulder pathology is advanced. One reason is fear of further loss of independence during the recovery process from postoperative immobilization. Another is the likelihood of need for postoperative transfer to a skilled nursing facility which is a daunting place, especially for the younger patient.
The examination of the neurologically impaired shoulder should be concentrated on taking an inventory of what the patient has, what they need, and what they can spare. A multidisciplinary approach including surgeon, physical and occupational therapist, social worker, and physiatrist is ideal. Emphasis that arthroplasty can give back something but not always everything helps to set realistic expectations at first meeting and in our experience has been the best strategy.
THE WEIGHT-BEARING SHOULDER
Wheelchair-dependent patients pose several challenges to shoulder arthroplasty. Although they have relatively normal glenohumeral anatomy, the increased functional demand required of the shoulder to propel a wheelchair and for transfers leads to a high incidence of shoulder pathology over time. However, as medical care continues to improve the survival of patients who sustain cerebrovascular accidents (CVAs) or traumatic spinal cord injuries resulting in paraplegia, the prevalence of wheelchair-dependent patients will continue to increase.
Biomechanically, the push phase of wheelchair propulsion in which the arm is extended and internally rotated has been shown to increase vertical force across the shoulder over threefold and posterior force twofold1
,2 (FIGURE 47.1)
. This increased stress over time explains the greater incidence of rotator cuff lesions in wheelchair users as compared with ambulatory individuals (63% vs 15%).3
Shoulder dysfunction in wheelchair users increases in direct correlation with age and duration of wheelchair use and not only limits independence but also can lead to depression over time.4
Previous studies have shown rotator cuff repair to be successful in wheelchair users in the short term but retears are common over time (as high as 40% in some series).5
This pattern is echoed in the results of total shoulder arthroplasty (TSA) where rotator cuff failure is a near inevitability over time if the individual continues to bear weight through the shoulder.10
This has led some to prefer primary reverse shoulder arthroplasty (RSA) in wheelchair-dependent patients. In the largest series to date, 83% of wheelchair ambulators were satisfied with their RSA; however, early complications (instability, glenoid baseplate loosening), late complications (periprosthetic fracture), and a notching rate of 42% make it far from ideal.12
THE SPASTIC SHOULDER
Spasticity results in increased muscle tone secondary to central neurologic dysfunction. Over time, this increased muscle tone can lead to painful contractures and eventual arthrosis. Although it is very uncommon for patients with spasticity to present for consideration of shoulder arthroplasty, patients with cerebral palsy (CP) as well as those who have survived a traumatic brain injury or CVA represent the majority of patients in this category. In individuals with CP, spasticity most often results in extension, adduction, and internal rotation contractures of the shoulder.13
In addition, altered muscular activity can predispose to recurrent joint subluxation, abnormal joint morphology, and premature arthritis. Previous studies have shown physical therapy, occupational therapy, bracing, botulinum toxin injections, soft tissue releases, and musculotendinous lengthening of spastic muscle units to be effective in correcting the internal rotation deformity prior to the onset of arthritis.14
In the setting of arthritis, both RSA and TSA have been performed with success, albeit in a few small case series with mixed functional results.13
Overall, RSA has been associated with better function and fewer complications than TSA, but long-term data are lacking.14
WordPress theme by UFO themes