CORR Insights®: What Range of Motion is Achieved Five Years After an External Rotationplasty of the Shoulder in Infants with Obstetric Brachial Plexus Injury?

Where Are We Now? There is abundant work on brachial plexus birth palsies and I want to highlight current literature on the indications and results of soft-tissue releases and tendon transfers. While the subscapularis is the most commonly released tendon in this setting, other soft-tissue structures that can be released include the anterior capsule, the coracohumeral ligament, and the pectoralis major (usually as a z-plasty); resection of the coracoid sometimes is done to achieve improvement of global abduction and external rotation of the shoulder. A meta-analysis published in 2013 showed open release of the subscapularis was superior to arthroscopic release to improve global abduction of the shoulder, but improvement of external rotation between the two groups was the same [5]. In contrast, another study found that arthroscopic release of the subscapularis was superior to open z-plasty of the pectoralis major when measuring abduction, Mallet scores, active external rotation and hand-to-head motion. All the children in this study also had latissimus dorsi and teres major tendon transfers done at the same time as the soft-tissue release. It is important to note that this study demonstrated improvement in all children, but recommended consideration of arthroscopic soft-tissue release since it is less invasive [9]. Finally, two studies found remodeling of the glenohumeral joint if the mechanics of the shoulder are restored early. They used MRI or CT to demonstrate a more-central position of the humeral head on the glenoid and improvement of the glenoid retroversion [1, 4]. Surgeons need to know that remodeling is possible if these procedures are done early enough and not to delay treatment. Two studies looking specifically at the child’s age at the time of procedure and remodeling potential found that performing soft-tissue releases and tendon transfers on children up to 5 years of age will produce sufficient remodeling over time [3, 4], which tends to decrease the likelihood that humeral osteotomy will be indicated. There is at least agreement that the most helpful tendon transfers include the latissimus dorsi and the teres major [1, 6, 7, 9, 11]. This helps researchers in the field focus on the questions that we do not have answered yet. In the current study, Sarac and colleagues [10] found that young children with obstetric brachial plexus palsies can benefit from soft-tissue release and when there is a lack of active external rotation, a tendon transfer should be added. While these results echo the findings in earlier studies [1, 4, 6, 8], the current study is unique because it had a large number of children and 5-year follow-up. Indeed, the majority of the literature on this topic are small case series or small retrospective reviews. Where Do We Need To Go? We need to define more clearly the indications for soft-tissue release, tendon transfers, and humeral osteotomies for the treatment of brachial plexus birth palsies. If this was easy, it would have been done already; the rarity of this diagnosis makes this line of work challenging, but no less important. Soft-tissue releases and tendon transfers seem to have the best results when performed in toddlers and young children, but some will recover spontaneously. This leaves us with the need for clarity on how long we ought to observe these patients for signs of recovery before recommending surgery. Some children do not follow commands and are fearful of providers making it difficult to assess their external rotation strength and active ROM. Some studies have advocated for MRIs as a part of the decision algorithm [8], but in this population, a general anesthetic or sedation is often required and the risks of an anesthetic should not be taken lightly. CT scans can frequently be done in young children without sedation, but the radiation associated with the scan makes them unfavorable. We still have to answer the following questions: At what age should soft-tissue release be done? Should the soft-tissue release be done first and a tendon transfer later or should they be done at one time? What type of soft-tissue release is best at gaining function with minimal complications? What role does MRI and electromyography (EMG) play in determining treatment? Should releases be done open or arthroscopically? Finally, we need to develop ways to evaluate muscle recovery/reinnervation in infants and toddlers. Keeping in mind the side effects from general anesthetics in patients younger than 2 years of age, and the importance of glenohumeral joint remodeling, perhaps the best timing of surgery would be between the ages of 2 and 4—as long as we can rule out children who will show spontaneous recovery. How Do We Get There? To better clarify our general indications for surgery to release shoulder contractures arising from obstetric brachial plexus injuries, we need large studies that are prospective with long-term follow-up. Comparing the available soft-tissue releases—of which there are many, both open and arthroscopic—is likely to be a real challenge because these diagnoses are mercifully rare. Still, a well-designed, multi-center, prospective study could answer the questions above, lead to standardization across centers, and provide the number of patients necessary to sufficiently power the data. The Mallet grading system and patient-reported outcome measures can be used to determine active/passive ROM of the glenohumeral joint and the ability to perform activities of daily living and ability to participate in sports. Even though this type of study would be ideal, they are difficult (and expensive) to coordinate. To overcome this problem, we should perform more well-designed prospective studies with long-term follow-up. This data can then be pooled together with meta-analyses to get the larger numbers of patients needed to make better conclusions. van der Holst and colleagues [11] recently did this (albeit with a small number of patients and short follow-up) in their well-designed prospective study that looked at the functional outcome in patients after internal rotational contracture release and tendon transfer over a 1-year period [11]. This could be followed by a meta-analyses of similar studies to gain conclusions from the current abundant literature on the topic [5]. However, these can be limited by slight differences in the study design of the included studies and variation among procedures performed. Researchers in the field can combat this by duplicating well-designed studies at their institution. We should also look at the use of EMG to aid in the work-up of these patients and follow the results of our interventions using functional improvement of shoulder abduction and external rotation. I believe that EMG can be used to evaluate for signs of reinnervation early to separate out the children that will likely spontaneously recover from those that will not. The next step would be to identify the type of soft-tissue release needed and MRI can be helpful with that decision making. MRI can also be useful as an outcome measure to determine the amount of remodeling seen of the glenohumeral joint in conjunction with physical exam measurement of abduction and external rotation using outcome surveys and Mallet scoring.