Techniques in Internal Impingement Surgery
Humeral Derotational Osteotomy
Internal impingement (impingement of the articular surface of the rotator cuff between the posterior superior glenoid and the greater tuberosity with the arm abducted and externally rotated) was initially described independently by both Jobe and Sidles and Walch et al (Fig. 18–1). Internal impingement predominately affects throwers and other overhead athletes. Opinions differ regarding the underlying etiology of this clinical entity. Jobe and Sidles believe that anterior glenohumeral instability is present, though often subtly, in these patients. We, however, have demonstrated this impingement in patients with no detectable anterior instability. Although anterior instability can certainly contribute to internal impingement, we do not believe it to be present in every patient with this injury.
Treatment of internal impingement is initially nonoperative. Avoidance of overhead activity is implemented and nonsteroidal anti-inflammatory drugs are initiated. Physiotherapy is employed, emphasizing rotator cuff strengthening with the arm at the side and strengthening the periscapular musculature, specifically the rhomboids. If symptoms persist despite non-operative treatment, diagnostic and therapeutic arthroscopy is performed. If diagnostic arthroscopy reveals instability with an associated avulsion of the inferior glenohumeral ligament, we believe it reasonable to perform a procedure, either arthroscopically or open, to address the anterior lesion in addition to debriding the partial thickness rotator cuff tear. After arthroscopic surgery, the patient undergoes a physiotherapy program similar to that utilized preoperatively for a period of 3 months. The technical description of arthroscopic debridement and arthroscopic and open shoulder stabilization is beyond the scope of this chapter.
Failing arthroscopic debridement and physiotherapy in the absence of instability, patients are left with two options: discontinuation of the provocative activity or humeral derotational osteotomy. Placing the humeral head in a more retroverted position prevents posterior superior glenoid impingement (Figs. 18–2A through D). The rationale for this procedure has recently been further justified by Crockett and colleagues, who demonstrated increased humeral retroversion in overhand throwers starting competitive throwing at a young age. It is hypothesized that this increased humeral retroversion is an adaptive mechanism occurring through the open physis when competitive throwing is initiated before skeletal maturity. Increased humeral retroversion would theoretically seem to offer a protective effect against internal impingement. Furthermore, little leaguer’s shoulder may be an extreme, pathologic form of this adaptive change. Humeral derotational osteotomy introduces the protective effect of increased humeral retroversion to patients without adequate retroversion to avoid the development of internal impingement.
1. Internal impingement failing nonoperative treatment and arthroscopic debridement
2. Absence of shoulder instability
1. Compromised skin or soft tissue
2. Ligamentous hyperlaxity
Mechanism of Injury
The mechanism of injury is repetitive hard throwing or similar overhead activity, with or without anterior instability, causing impingement of the articular surface of the rotator cuff between the posterior superior glenoid rim and the greater tuberosity.
1. Posterior shoulder pain without apprehension with shoulder abduction, external rotation, and extension
2. Painful testing of the supraspinatus
1. Anterior-posterior radiographs with the shoulder internally rotated, externally rotated, and in neutral are obtained. Additionally, a glenoid profile view (Bernageau view) is obtained. These views may demonstrate changes in the greater tuberosity (sclerosis, geodes) and/or the glenoid (sclerosis, geodes, rounding off).
2. Computed tomographic arthrography may further delineate bony changes of the greater tuberosity and glenoid and may demonstrate partial thickness supraspinatus tears. Humeral retroversion is measured using the technique of Laumann and Kramps (Fig. 18–3).
3. Alternatively, magnetic resonance arthrography can be used to evaluate the rotator cuff muscle and the glenoid labrum. Bony architecture is not as greatly defined on these images, and we have no experience measuring humeral retroversion using magnetic resonance imaging.
4. All patients should undergo dynamic arthroscopy confirming internal impingement with the arm in the provocative position. Arthroscopy further allows for delineation of additional soft tissue pathology (i.e., a posterior labral tear). Arthroscopy is typically performed at a prior surgical setting, establishing the diagnosis and treating the lesion with debridement. A repeat arthroscopy immediately preceding derotational humeral osteotomy is generally not indicated.