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Letters to the Editor |
56 Century Buildings, St Mary’s Parsonage, Manchester M3 2DD, England. e-mail: annheller@talk21.com
Editor:
I read with interest the article by Dr Pfirrmann and colleagues in the November 2001 issue of Radiology (1). They report three trochanteric subgluteus maximus bursae among 10 cadaveric specimens. In our experience (2), trochanteric bursae are more common and more variable than the authors describe. In a series of anatomic dissections performed in 16 hips from eight consecutive cadavers with an age range of 63–91 years, one or more subgluteus maximus bursae were identified in 13 specimens (seven female, six male). In two of the three specimens without bursae, there was evidence of previous surgery with protrusion of a metallic nail from the greater trochanter. In the third specimen, there was considerable scar tissue overlying the trochanter.
In each of the 13 specimens with subgluteus maximus bursae, a large bursa was located directly superficial to the common attachment of the gluteus medius and minimus and vastus lateralis muscles onto the greater trochanter (the deep bursa). In five specimens, two bursae were present, and these could be easily separated through a fascial plane. The smaller of these two (the superficial bursa) was in each case located on the deep surface of the gluteus maximus muscle in close association with the muscle fibers as they insert into the fascia lata and was reflected with it. In two other specimens, four bursae were present—two superficial and two deep bursae. We confirmed the existence of a bursal wall with histologic demonstration of a synovial lining (2).
Our data indicate that subgluteus maximus bursae at the level of the greater trochanter are an expected finding in older subjects and that bursae vary in number, position, and histologic appearance. These features have led to the hypothesis that these bursae may be acquired as a consequence of lateral displacement of the greater trochanter with recurrent impaction of the trochanter on the fascia lata; therefore, trochanteric bursitis is a true impingement syndrome. Thus, the sequence of events would be rotator cuff tear (3,4) involving the short abductor tendons, disuse atrophy of the involved muscles, loss of containment of the femoral head, lateral subluxation, impingement of the greater trochanter on the fascia lata, and development of bursitis.
This sequence of events may also be more common in the upper limbs than is recognized and may explain the absence of bursal surface tears in many subjects with subacromial bursal distention and clinical impingement. Thus, in both lower and upper limbs, bursitis would be an important marker of early mechanical failure of the joint and joint instability.
In the upper limbs, Neer and colleagues (5) documented an association between major abductor tendon tears and disorganization and destruction of articular structures. In the lower limbs, the possibility of chronic incompetence of the short abductor complex that leads to secondary articular change must be explored. With magnetic resonance imaging technology that allows detailed structural assessment of the dynamic and static stabilizers of the hip and defines muscle and tendon tears (6,7), it is possible that the systematic imaging evaluation of subjects with trochanteric bursitis may yield valuable structural and functional information. Tendon failure involving the short abductor group may be the initiating event in the development of classic osteoarthritis of the hip and may also be a major contributing factor in the evolution of other hip arthropathies.
REFERENCES
Department of Radiology, University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland* e-mail: christian@pfirrmann.ch
Department of Radiology, Veterans Administration Medical Center, San Diego, Calif
We appreciate the letter by Dr Heller and the interest in our study (1). We would like to comment on two points to help clarify some of the issues. The bursal cavities are frequently underestimated in their importance, and they even have been called "the Cinderellas of the body" (2). Further knowledge about the exact anatomy, variation in extent, and localization is therefore helpful.
The number "three" mentioned in the first paragraph of this letter to the editor does not refer to the frequency of the trochanteric bursa in our series. This number likely refers to how many contrast material–enhanced examinations of the trochanteric bursa were performed. As pointed out in our Results section, the trochanteric bursa was detected in all cadaveric specimens (10 of 10 cadaveric hips) and in all but one volunteer (10 of 11 volunteer hips). The observation of the anatomic dissection described by Dr Heller therefore confirms the results of our research. The trochanteric bursa is the most constantly present bursa around the greater trochanter of the femur.
The nomenclature used in the literature for the different bursal cavities is inconsistent. There are about 20 bursae described around the hip joint, with variable extent and prevalence (3). Deep to the gluteus maximus muscle, two bursae are usually present: the trochanteric bursa and the sublgluteus maximus bursa. The trochanteric bursa is located beneath the gluteus maximus muscle and the iliotibial tract, and it covers the posterior facet of the greater trochanter, the distal lateral part of the gluteus medius tendon, and the proximal part of the vastus lateralis insertion (1). The subgluteus maximus bursa is located more distal to the trochanteric bursa. This bursa lies between the distal attachment of the gluteus maximus muscle and the dorsal aspect of the femur (3). The subgluteus maximus bursa was not investigated in our study because it is located distal to the greater trochanter. The trochanteric bursa and the subgluteus maximus bursa may communicate.
REFERENCES
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