Abstract & Commentary
Synopsis: Patients with normal anatomic variants of the anterosuperior labrum, including a sublabral hole or a Buford complex, were 5-7 times more likely, respectively, to have SLAP lesions at arthroscopy.
Source: Ilahi OA, et al. Variants of the anterosuperior glenoid labrum and associated pathology. Arthroscopy. 2002; 18(8):882-886.
Variants of the anterosuperior labrum have been relatively recently described as shoulder arthroscopy and MRI techniques have improved. The anterosuperior labrum can have a normal sublabral hole or foramen from the 1 to 3 o’clock position that is not pathological or associated with instability. Alternatively, the labrum can be absent in this area with a bare glenoid rim, termed a Buford complex. In about 75% of these cases, the middle glenohumeral ligament is thickened or cord-like. Beyond this, little is known about these variants.
Ilahi and colleagues add to our understanding of these anatomic variants as they report their arthroscopic findings in a prospective series of 108 consecutive shoulders. They found an incidence of 18.5% for sublabral foramens and 6.5% for Buford complexes. Most of these patients also had absent superior glenohumeral ligaments in association with a thickened middle glenohumeral ligament. In fact, a discernable superior glenohumeral ligament could only be found in less than half of all shoulders.
The vast majority of patients were scoped for rotator cuff or impingement problems, with only 5% diagnosed preoperatively and 23% intraoperatively with a significant SLAP lesion (type I excluded). Interestingly, they found a strong correlation between anterosuperior labral variants and SLAP lesions. Of the 25 patients with a significant SLAP lesion, 40% had a sublabral foramen and 20% had a Buford complex. If the numbers are turned around, 50% of patients with a sublabral foramen and 71% of patients with a Buford complex had a SLAP lesion, compared to a 12% incidence in all other shoulders.
Comment by David R. Diduch, MS, MD
The superior labrum can be a difficult area to diagnose pathology on MRI and even at arthroscopy. Not only is there variability in attachments and mobility of the biceps and labrum, but also we have these anatomic variants to sort out. Ilahi et al help us by supplying good numbers that provide warning signs for SLAP tears. In their series, patients with sublabral holes or Buford complexes were at least 50% likely to have a SLAP tear if they presented with shoulder pain requiring arthroscopy. In fact, they were at 5- to 7-fold greater risk than other patients to have a SLAP lesion.
Clearly, this risk factor can aid in diagnosis. But why does this association exist? Ilahi et al theorize that a less-than-stable anterosuperior labrum puts more stress on the superior labrum and biceps attachment, thereby putting it at risk to pull off with trauma or twisting during throwing activities. They do not call these anatomic variants pathologic or associate them with patterns of instability. Thus, one should not treat the sublabral foramen or Buford complex by any type of reattachment if recognized at arthroscopy. Indeed, patients can lose rotational motion if the anterosuperior labrum is attached where it never was before.
The weakness of this study is that the accurate diagnosis of SLAP lesions can be in question even at arthroscopy, possibly affecting Ilahi et al’s numbers. However, the clear benefit of this study is that it provides us a warning sign and a possible correlation as we try to determine normal vs pathological bicep attachment on MRI and at arthroscopy.
Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports.