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Shoulder and ElbowFurther Opinion

Prevalence and characteristics of asymptomatic tears of the rotator cuff

S Moosmayer, A Larmo, R Tariq, H-J Smith

J Bone Joint Surg [Br] 2009;91-B:196-200.

This interesting epidemiological study addresses the prevalence of asymptomatic full-thickness tears of the rotator cuff in a community-based population of 420 subjects aged between 50 and 79 years. The integrity of the rotator cuff was determined by sonography and correlated to range of movement and strength. The accuracy of high-resolution ultrasonography in detecting full-thickness rotator cuff tears in shoulders not previously treated surgically has been reported to be as high as 96%.1 This study, matching the previous literature, demonstrates that ultrasonography, an operator-dependent imaging modality, is highly accurate in detecting full-thickness cuff tears if performed by an adequately trained operator. It thus strengthens the case for applying ultrasound, which has so far gained limited acceptance by orthopaedic surgeons, in detecting rotator cuff tears. Conversely, the technique is less sensitive in detecting partial tears and biceps ruptures; in such cases MRI is required for a correct diagnosis.

The study reports a prevalence of asymptomatic cuff tears of 7.6%, and a significant correlation with subject age. Sher et al2 reported a prevalence of 30% in the general population and Lehman et al3 a value of 17% in cadavers during dissection.

The discrepancy is explained by the authors by technological improvements resulting in more reliable sonograms, the higher average age of the patients examined by Sher et al,2 and the inclusion of symptomatic cuff tears in the study by Lehman et al.3

False negatives could be detected and eliminated by meticulous physical examination when symptoms are unclear, and by using MRI when ultrasound findings are not conclusive.

As regards the presence of bilateral lesions (11/32 patients), the data of Moosmayer et al seem to agree with the findings of Yamaguchi’s team,4 who observed a genetic predisposition for cuff disease in a group of patients particularly prone to cuff tears. These considerations perfectly match Carr’s, who found that age, environment and genetic predisposition are risk factors for cuff tears.5 There are other factors, including occupational and sport activities. This paper addresses an important issue: subjects with an asymptomatic lesion have impaired rotator cuff function and are more prone to developing symptomatic tears even with minor trauma.

When a pain-free lesion is detected surgery is not required, but both surgeon and patient can be more confident that progression of the tear or the development of cuff-related degenerative changes can be slowed down by maintaining rotator cuff balance through physiotherapy.

This consideration is of great importance in balancing the economic aspects of patient management. The surgeon should achieve a correct diagnosis in symptomatic patients and screen them for predisposing factors. It still remains unclear whether ultrasound examination, even one performed with a high-resolution device, provides sufficient grounds to recommend surgery in symptomatic patients. Recent studies have demonstrated different patterns of muscle activation in patients with symptomatic and asymptomatic cuff tears.6 The authors evaluated electromyographic activity and kinematic data in symptomatic and asymptomatic cuffs, highlighting a tendency to increased muscle activation during all tasks in both groups compared with normal subjects. Asymptomatic subjects had increased firing of the intact subscapularis, whereas symptomatic subjects continued to rely on torn rotator cuff tendons and periscapular muscle substitution, resulting in impaired function. Detection of differential shoulder muscle firing patterns in patients with rotator cuff pathology could explain the presence or absence of symptoms.

A simple clinical question arises from this study: do symptomatic cuff lesions require surgical treatment or may they be treated conservatively in the hope of a favorable outcome? The question is critical, because there is no evidence that the source of the pain in these patients is the cuff tear. Subacromial/subdeltoid bursal effusion and biceps tendon sheath effusion can change the natural course of an asymptomatic cuff tear. So the problem is really to find what makes a tear symptomatic so as to avoid surgery when the problem can be addressed by a conservative approach. The future of high-definition ultrasound clearly lies in the possibility of associating dynamic testing to resolve uncertain cases and to detect early cuff lesions or an unstable long head of biceps that can lead to a subscapularis tear. This study defines a group of asymptomatic patients with a preclinical condition that, once discovered, should be treated with physiotherapy and monitored over the years.

References

1. Teefey SA, Hasan SA, Middleton WD, et al. Ultrasonography of the rotator cuff: a comparison of ultrasonographic and arthroscopic findings in one hundred consecutive cases. J Bone Joint Surg [Am] 2000;82-A:498-504.
2. Sher JS, Uribe JW, Posada A, Murphy BJ, Zlatkin MB. Abnormal findings on magnetic resonance images of asymptomatic shoulders. J Bone Joint Surg [Am] 1995;77-A:10-15.
3. Lehman C, Cuomo F, Kummer FJ, Zuckerman JD. The incidence of full thickness rotator cuff tears in a large cadaveric population. Bull Hosp Jt Dis 1995;54:30-1.
4. Teefey SA, Rubin DA, Middleton WD, et al. Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases. J Bone Joint Surg [Am] 2004;86-A:708-16.
5. Harvie P, Ostlere SJ, Teh J, et al. Genetic influences in the aetiology of tears of the rotator cuff: sibling risk of a full-thickness tear. J Bone Joint Surg [Br] 2004;86-B:696-700.
6.  Kelly BT, Williams RJ, Cordasco FA, et al. Differential patterns of muscle activation in patients with symptomatic and asymptomatic rotator cuff tears. J Shoulder Elbow Surg 2005;14:165-71.

 

Porcellini G

Hospital "D.Cervesi", Cattolica (RN), Italy

E-mail: shoulder@orthoweb.net