The Hip, Part 3: More on Hip Rim Syndromes and Labral Tears→

July 13, 2011/ The Gait Guys

Tomorrow, in Part 4 (the last part), we will talk about functional hip problems in runners and cyclists but today we will finish up this little topic on some of the internal hip derangements. For tomorrow, remember our key words from the other day, INTERNAL HIP ROTATION range……. it is important stuff when we discuss gait and the hip problems that result from pathologic gait patterns.

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Labral detachments and tears are the most common clinically significant abnormalities to be identified. To date it still seems that evaluation of the patient with chronic mechanical hip pain remains somewhat of a diagnostic dilemma for physicians. The differential diagnosis is diverse including common entities such as osteoarthritis, fracture, and avascular necrosis, as well as less common entities including pigmented villonodular synovitis, synovial osteochondromatosis, snapping hip syndrome, and hemorrhage into the ligamentum teres. Childhood disorders such as Perthes disease and dysplasia also need to be considered with adolescents. Similar to findings in the knee and shoulder, radiographs appear normal in the vast majority of patients with internal derangement as a cause for hip symptoms. In one study, labral lesions were identified at arthroscopy in 55% of patients with intractable hip pain.  
Imaging: As with other joints in the body, magnetic resonance (MR) arthrography of the hip has emerged as a technique for diagnosis of internal derangement of the hip. In addition to depicting labral lesions, MR arthrography may also depict intraarticular loose bodies, osteochondral abnormalities, and abnormalities of the supporting soft-tissue structures. Radiographs in patients with labral tears are typically unremarkable. If early osteoarthritic disease is present, the pain is out of proportion to the radiographic changes.

Labral lesions have a strong correlation with symptoms such as: anterior inguinal pain, painful clicking, transient locking. “giving way” of the hip. Pain may be reproduced with flexion and internal rotation of the hip. An audible click may also be present at times. The patient history usually does not reveal significant trauma. The onset of pain may be related to sports and may involve a mild twisting or slipping injury. Major trauma such as dislocation may result in labral tear.  
Patients with developmental dysplasia of the hip are at increased risk for labral tears and abnormalities of the labral rim. The Rim syndromes are categorized by two types of acetabular dysplasia; one being the incongruent oval shaped acetabulum the other being the congruent, spherical acetabulum with poor lateral coverage of the femur head which leads to fatigue fractures of the acetabulum socket and articular and interosseous cyst formation. In patients with developmental dysplasia, the acetabular rim and the labrum are placed under increased stress.  The possibility of a pathologic labral condition should be considered in individuals with developmental dysplasia of the hip in whom the pain is disproportionate to the radiographic changes, as well as in patients who have not experienced significant improvement after osteotomy. The fact that a detached labrum increases the risk of failure of treatment has been recognized.

Summary:
Mechanical hip pain can be a real enigma unless your doctor really knows their stuff. Not many studies talk about neuromuscular support, muscular function and movement patterns of the hip largely because the education in this area is poor, in our opinion. Physician skill level with years of experience is also a real challenge when dealing with mechanical hip pain and the causes (as we have discussed here) of anatomic pathology that might occur when the normal hip mechanics are challenged. Add an abnormal gait pattern to the mix and it is no wonder why some hip problems go undiagnosed in the early stages of problem.
A pathologic labral conditions, detachments or tears, are a common cause of chronic hip pain, and MR arthrography of the hip is the imaging procedure of choice for identifying an abnormal labrum. Detachments are more common than tears and are identified on the basis of the presence of contrast material interposed at the acetabular-labral junction.  
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There is not a ton of literature out on the Rim syndromes, since some of you have been asking about it. Here is an article we found. Link for article purchase is at the header of today’s blog.
J Bone Joint Surg Br. 1991 May;73(3):423-9.
The acetabular rim syndrome. A clinical presentation of dysplasia of the hip.
Klaue K, Durnin CW, Ganz R.
Abstract
The acetabular rim syndrome is a pathological entity which we illustrate by reference to 29 cases. The syndrome is a precursor of osteoarthritis of the hip secondary to acetabular dysplasia. The symptoms are pain and impaired function. All our cases were treated by operation which consisted in most instances of re-orientation of the acetabulum by peri-acetabular osteotomy and arthrotomy of the hip. In all cases, the limbus was found to be detached from the bony rim of the acetabulum. In several instances there was a separated bone fragment, or ‘os acetabuli’ as well. In acetabular dysplasia, the acetabular rim is subject to abnormal stress which may cause the limbus to rupture, and a fragment of bone to separate from the adjacent bone margin. Dysplastic acetabuli may be classified into two radiological types. In type I there is an incongruent shallow acetabulum. In type II the acetabulum is congruent but the coverage of the femoral head is deficient.