To the Editor:

I read with considerable interest the article entitled, "Congenital Absence of the Long Head of the Biceps Tendon" by Franco, et al, (2005;87:1584-6). This case report appears to be important in demonstrating one of the anatomical variations in the biceps, which has been widely recognized as having wide-ranging and abundant variations in the proximal part.

It seemed to me, however, that the authors do not consider the possibility that the tendon of the long head of the biceps is extrasynovial, passing through the supraspinatus tendon(1) or lying within the fibrous capsule(2). Furthermore, the authors did not include in their references earlier anatomical studies which demonstrated the absence of the intra-articular part of the long head of the biceps(3-5).

In the discussion, the authors pointed out the relationship between absence of the long head and anterior shoulder instability. Although I agree that the tendon of the long head of the biceps functions as a dynamic stabilizer of the anterior aspect of the shoulder, its function as a dynamic stabilizer against anterior instability may be minor in the normal shoulder, considering the clinical facts that anterior shoulder instability does not develop in people who have undergone tenodesis or tenolysis of the long head of the biceps. The fact that absence of the long head of the biceps was reported in three patients with anterior shoulder instability appears to be a reflection of the tendency for the majority of arthroscopic surgery to be performed to correct shoulder instability.

References:

1. Ogawa K, Naniwa T. Rare variation of the biceps: A possible cause of degeneration of the rotator cuff. J Shoulder Elbow Surg, 1998;7:295-7.

2. Rojvanit V. Arthroscopy of the shoulder joint: A cadaver and clinical study: Part 1 cadaver study. Nippon Seikeigeka Gakkai Zasshi, 1984;58: 1035-46.

3. Craig JD. Anomaly of the long tendon of the biceps muscle of the arm. N Y Med Rec, 1899;56:514.

4. Meyer AW. Bilateral absence of the tendon of the long head of the biceps in one subject, and five instances of secondary attachment of the tendon to the articular capsule and tuberosities, with special reference to the effect of these anomalous conditions upon the intertubercular sulcus. J Anat Physiol, 1914;48:133-5.

5. Greig HW, Anson BJ, Budinger JM. Variations in the form and attachments of the biceps brachii muscle. Q Bull Northwestern Med School 1952;26:241- 4.