The Acetabular Labral Tear: An Arthroscopic Classification Lafayette A. Lage, M.D., Jig V. Patel, M.B., B.S., and Richard N. Villar, B.Sc (Hons), M.S., F.R.C.S.
Summary: Acetabular labral tears are well recognized in the pathology of hip disease. The patterns of such tears found in 37 patients undergoing hip arthroscopy have been analyzed. Distinct categories of labral tear were found, and may be classified in terms of etiology (traumatic, 18.9% of cases; degenerative, 48.6%; idiopathic, 27.1%; congenital, 5.4%) and morphology (radial flap, 56.8%; radial fibrillated, 21.6%; longitudinal peripheral, 16.2%; unstable, 5.4%). Key Words: Labmm--Arthroscopy--Hip joint--Classification--Labral tear.
he acetabular labrum has a number of important functions. These include containment of the femoral head during acetabular development,~ and stabilization of the hip 2 by augmentation of the articular surface. Labral lesions have been shown to produce symptoms, the most common being pain) Tears can now be diagnosed under direct vision with the advent of hip arthroscopy. Previously, these lesions were diagnosed by arthrography. 4 Some regard arthrography as useful because of the response of the patient to the injected local anesthetic as well as a claim that labral tears, when present, may be identified in most cases, s Not all agree that arthrography is always successful, 6 some claiming it has significant false-negative rates. 7 Magnetic resonance image (MRI) scanning, advanced though it may be, has not yet been shown to have the accuracy of hip arthroscopy for all intraarticular hip lesions. 8 Our patients all underwent basic examination and plain radiographic assessment before hip arthroscopy. In selected cases, MR1 scanning was also performed, but our previous experience with this tech-
From the Instituto de Ortopedia e Traumatologia, University of Sao Paulo, Brazil (L.A.L.), and the Department of Orthopaedics, Addenbrooke's Hospital, Cambridge, United Kingdom (J.V.P., R.N.V.). Address correspondence and reprint requests to Mr. Richard N. Villar, F.R.C.S., The Vineyard, WindmillHill, Saffron Walden, CBIO 1RR, United Kingdom. © 1996 by the Arthroscopy Association of North America 0749-8063/96/1203-130753.00/0
nique had not proved to be always helpful. 8 We thus did not perform the investigation as routine, preferring to proceed directly to hip arthroscopy as a result of the considerable experience of our unit with the technique. Arthrography, computed tomographic (CT) arthrography, or plain CT scanning were likewise not performed. A classification of labral tears is needed to alert the orthopaedic surgeon to the morphology and likely etiology of lesions that may be encountered in this developing field. As yet there is no such classification in the literature. PATIENTS AND M E T H O D S Hip arthroscopy was performed in 367 patients for whom the predominant symptom was pain. All arthroscopic procedures were performed by the same surgeon (R.N.V.). Data were gathered prospectively, with all lesions being photographed to ensure adequate facility for subsequent retrospective cross-checking. The first 100 patients were excluded from the study as this represented an acceptable learning curve for the operator. Any previous history of injury to the hip was carefully recorded. A traumatic etiology for a labral tear was only proposed if there was a clear history of injury in the absence of arthroscopic evidence of labral or articular cartilage degeneration. Injury could be major (e.g., a fracture-dislocation) or minor (e.g., a simple twisting injury), but had to unquestionably involve the hip.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 12, No 3 (June), 1996: pp 269-272
L. A. LAGE ET AL.
F I G 1. Diagrammatic representation of morphology of labral tears. Unstable tears are excluded.
All arthroscopic procedures were performed using a specialist hip distractor. 9'1° This permitted longitudinal and horizontal forces to be applied to the hip joint allowing a resultant force parallel to the axis of the femoral neck. Hence, greater access and vision were achieved compared with a standard orthopaedic traction table. A lateral (supratrochanteric) approach was used in all cases. At operation, the location and morphology of the tear were recorded and the hip was rotated internally and externally to detect any evidence of labral instability. Record was also made of any associated degenerative change within the joint.
Degenerative (18 cases, 48.6%): Degenerative tears were so classified if any degenerative change could be seen within articular cartilage, or within the labrum itself. Idiopathic (10 cases, 27.1%): These were tears for which there was no history of injury, and no arthroscopically identifiable degenerative change. Congenital (2 cases, 5.4%): This term is used to classify the two subluxing acetabular labra identified, that were structurally normal, but functionally abnormal. Morphological Classification
RESULTS For the 267 patients (267 hips) who underwent arthroscopy, the median age was 40 years (range 6 to 82 years). 149 (55.8%) were female, and 118 (44.2%) were male. Within the study group, 37 labral tears were found (13.9%). From these 37 labral tears, four distinct etiological and four distinct morphological groups were identified:
Etiologic Classification Traumatic (7 cases, 18.9%): Traumatic tears have already been discussed, but were classified as such if there had been a clear history of hip injury, and yet no sign of degenerative change within either labrum or articular cartilage.
See Fig 1 for a diagram of the morphology of labral tears. Radial Flap (21 cases, 56.8%): Such tears involved disruption of the free margin of the labrum with the consequent formation of a discrete flap (Fig 2). Radial Fibrillated (8 cases, 21.6%): Fibrillated tears had the appearance of a shaving brush, and were generally of a hairy appearance at the free margin of the labrum. These were more common in the presence of degenerative disease (Fig 3). Longitudinal Peripheral (6 cases, 16.2 %): Longitudinal tears were of variable length, along the acetabular insertion of the labrum (Fig 4). Unstable (2 cases, 5.4%): Unstable tears were a reflection of abnormal labral function rather than
THE ACETABULAR LABRAL TEAR
FIG 2. Radial flap tear (right hip, supratrochanteric portal). (Courtesy of R. N. Villar.) shape, representing the two subluxing labra that form part of this series (Fig 5). O f the 37 labral tears seen, 23 (62.2%) were anteriorly situated, 11 (29.7%) posterior, and 3 (8.1%) superior. DISCUSSION The purpose of this study was to develop a simple classification of gross labral pathology. The series of
FIG 3. Radial fibrillated tear (fight hip, supratrochanteric portal). (Courtesy of R. N. Villar.)
FIG 4. Longitudinal peripheral tear (right hip, supratrochanteric portal). (Courtesy of R. N. Villar.)
37 labral tears is small. However, this still represents the largest series in the literature. A number of suggested etiologies for the labral tear have been recorded, including hip dysplasia 7'11 and trauma. 12'j3 However, with rare exception, 7'14 diagnosis and m a n a g e m e n t have not been arthroscopic and clas-
FIG 5. An unstable, subluxing, acetabular labrum (fight hip, supratrochanteric portal). (Courtesy of R. N. Villar.)
L. A. LAGE ET AL.
sification limited. Presentation is variable, and is not the purpose of this article. However, the majority present with pain, some with a pain and click. A few, the minority, present with a click from the hip alone. Our data have shown four basic etiologic and four basic morphological patterns of acetabular labral tear. In 1988, Ikeda et al. 15described seven labral tears diagnosed by arthroscopy. All were longitudinal and located at the posterosuperior margin of the acetabulum. Our findings suggest that labral tears can occur at any point on the circumference of the labrum and are not exclusively confined to its posterosuperior aspect. Indeed, 62% of our tears were anteriorly situated. Longitudinal peripheral tears were also in a minority for our patients, representing 16.2% of the total. We were also unable to identify any patient with a bucket handle tear of the labrum, previously described by various investigators. 1244'16 Only one of these articles j4 reported an arthroscopic diagnosis. However, it is conceivable that earlier reports of a bucket handle tear may simply have been an extreme form of our peripheral longitudinal variety. The unstable labrum is worthy of separate note. Although not truly torn, two of our cases showed instability of the acetabular labrum. Presenting as a 'clicky' hip, both were in teenage girls, were associated with generalized ligamentous laxity, and showed marked subluxation of the labrum during internal and external rotation performed during hip arthroscopy. We regard this as a congenital labral defect. The frequency of labral tears has only rarely been reported. Suzuki et al. 7 performed 49 hip arthroscopies in 45 patients for a variety of reasons. In 10.2% of these procedures, a labral tear was found, the frequency in our series being 13.9%. Arthroscopy of the hip is a developing field. The advantages of direct vision of the hip joint over other, varied, imaging techniques (e.g., MRI, arthrography) are clear, although it must of course be remembered that arthroscopy is an invasive technique. Despite this, it does carry the opportunity for therapeutic intervention. In all our cases, excluding unstable labra, the treatment of choice was partial acetabular labrectomy, the labral tear being excised back to stable tissue. It is not the purpose of this article to discuss the results of such resection. That is for subsequent research. How-
ever, it appears that the partial resection of an isolated, traumatic, labral tear can improve symptoms in up to 75% of patients. Those who do badly tend to be patients with degenerative or congenital labral pathology. Since the days when the torn labrum was first recognised as a cause of hip pain, ~7 our experience has enlarged. One must hope that the above classification will allow better analysis of the long-term results of such a procedure and a better appreciation of the mechanism of injury of this poorly understood structure. REFERENCES 1. Kim Y-H. Acetabular dysplasia and osteoarthritis developed by an eversion of the acetabular labrum. Clin Orthop 1987;215: 289-293. 2. Takechi H, Nagashima H, lto S. Intra-articular pressure of the hip joint outside and inside the labrum..I Jpn Orthop Assoc 1982;56:529-536. 3. Ueo T, Suzuki S, lwasaki R, Yosikawa J. Rupture of the labra acetabularis as a cause of hip pain detected arthroscopically and partial limbectomy for successful pain relief. Arthroscopy 1990; 6:48-51. 4. Nishina T, Saito S, Ohzono K, Shimizu N, Hosoya T, Ono K. Chiari pelvic osteotomy for osteoarthritis. The influence of the torn and detached acetabular labrum. J Bone Joint Surg Br 1990; 72:765-769. 5. Fitzgerald RH Jr. Acetabular labrum tears: Diagnosis and treatment. Clin Orthop Rel Res 1995;311:60-68. 6. Klaue K, Durnin CW, Ganz R. The acetabular rim syndrome. A clinical presentation of dysplasia of the hip. J Bone Joint Surg Br 1991;73:423-429. 7. Suzuki S, Awaya G, Okada Y, Maekawa M, Ikeda T, Tada H. Arthroscopic diagnosis of ruptured acetabular labrum. Acta Orthop Scand 1986;57:513-515. 8. Edwards D, Lomas D, Villar R. Comparison of MRI and hip arthroscopy in diagnosis of disorders of the hip joint. J Bone Joint Surg Br 1994;76:52 (suppl 1). 9. Villar R. The technique of hip arthroscopy. In: Hip arthroscopy. Oxford: Butterworth Heinemann 1992:39-53. 10. Glick JM, Sampson TG, Gordon RB, Behr JT, Schmidt E. Hip arthroscopy by the lateral approach. Arthroscopy 1987;3:4-12. 11. Dorrel JH, Catterall A. The torn acetabular labrnm. J Bone Joint Surg Br 1986;68:400-403. 12. Paterson I. The torn acetabular labrum. A block to reduction of a dislocated hip. J Bone Joint Surg Br 1957;39:306-309. 13. Dameron TB Jr. Bucket handle tear of acetabular labrum accompanying posterior dislocation of the hip. J Bone Joint Surg Am 1959;4l:131-134. 14. Ide T, Akamatsu N, Nakajima I. Arthroscopic surgery of the hip joint. Arthroscopy 199[;7:204-211. 15. Ikeda T, Awaya G, Suzuki S, Okada Y, Tada H. Torn acetabular labrum in young patients. J Bone Joint Surg Br 1988; 70:13-16. 16. Kaelin A. Une cause rare de blocage traumatique de la hanche chez l'enfant. Int Orthop (S1COT) 1984;8:9-12. 17. Altenberg AR. Acetabular labrum tears: A cause of hip pain and degenerative arthritis. South Med J 1977; 70:174-175.