Traumatic anterior dislocation of the hip is an uncommon injury. In a large series of traumatic dislocations of the hip reviewed by Epstein,4 the incidence of anterior dislocation was only 10%'; while Brav reported 66 (12.6%) anterior dislocations among 523 traumatic hip dislocations.2 None of the anterior dislocations in Brav's series required open reduction. Among 37 anterior dislocations reviewed by Epstein, only one was irreducible, requiring open reduction, while one other case underwent primary open reduction.1 There have been very few Other reports of failure of closed reduction necessitating an open procedure.1'3 One of the authors (S. M.) had an opportunity to reduce four anterior dislocations in the past five years. In all but one, reduction was obtained without any difficulty. One case, which could not be reduced closed, required open reduction. The purpose of this paper is to describe the lesion and treatment, and discuss both.
A 19-year-old man, a passenger in an automobile accident, was unable to recall the exact mechanism of injury. He was brought to the Emergency Room of City Hospital Center at Elmhurst by ambulance. The right hip was fixed in abduction, flexion and external rotation. Movements of the right hip were extremely painful. He had a good peripheral and femoral pulse, and sensations in this lower extremity were intact. Patient also had lacerations of his tongue. Roentgenograms of the pelvis and hip disclosed an obturator type of anterior dislocation of the right hip without any acetabular or femoral fractures (Fig. 1). One gentle attempt at closed reduction under analgesia in the Emergency Room failed to reduce the dislocation. The patient was then admitted and taken to the operating room within four hours of injury. Under general anesthesia and with good muscle relaxation, a closed reduction was attempted by a sustained traction in the line of the femur, gentle flexion of the hip with continued traction, and gentle internal rotation and adduction, a technique described by Epstein.' On failure to obtain closed reduction, the hip joint was exposed by Smith-Petersen's anterior approach. The following pathological anatomy was present;
1. The capsule of the hip joint was ruptured in the anterior portion, through which the head of the femur dislocated anteriorly.
2. The part of the iliofemoral ligament appeared intact and was felt as an extremely tight buttonholed structure about the anterolateral part of the femoral neck. Upon flexion, the tightness could be easily reduced.
Fig. I: Anteroposterior roentgenogram of the hip, showing obturator type of anterior dislocaion.
3. Insertion of the iliopsoas tendon on the lesser trochanter was intact. The tendon could be felt as a tight structure along the anterolateral part of the femoral neck.
4. The reflected head of the rectus femoris was also buttonholed by the head of the femur. Its lateral part was lying anteriorly, partially covering the neck, while the medial part of it was behind the head and neck overlying the anterior part of the acetabulum. The origin of the reflected head of the rectus femoris was found to be from a much wider area above the acetabulum than would be normally expected.
5. There was no fracture of the acetabulum or the head of the femur.
6. The ligamentum teres was found to be torn.
The reduction was once again attempted, this time trying to guide the femoral head into the acetabulum under direct vision, but the part of the rectus femoris interposed between the femoral head and acetabulum prevented it. The split reflected head of the rectus femoris was detached from its origin, allowing easy reduction through the torn capsule. Postoperatively, the patient was treated in skeletal traction for three weeks. Five months postinjury, the patient had no symptoms, had full range of movements of the hip, and roentgenograms revealed a concentrically-located normal-appearing hip joint (Fig. 2). Following this the patient was lost to followup.
Fig. 2: Anteroposterior roentgenogram of the hip five months after surgery, showing concentrically located hip.
The case presented here indicates that not all anterior dislocations of the hip are simple, and that one should always be prepared to perform open reduction if closed reduction fails. McFarlane reported a case of anterior dislocation of the hip that required open reduction because closed reduction failed.3 At operation, the head was found to have buttonholed the capsule between the iliofemoral and pubofemoral ligaments. He found the head of the femur partially covered by some torn fibers of the rectus femoris, which when retracted failed to disclose any muscle fibers behind the head to obstruct the reduction. In our case the reflected head of the rectus femoris was buttonholed by the head of the femur, part of which was lying between the head of the femur and the acetabulum resulting in failure of closed reduction. Detachment of this split origin of the muscle resulted in easy reduction of the dislocation. It must be mentioned that in this patient the origin of reflected head of rectus femoris was wider than usual, and this may have been responsible for this unusual complication.
One of the irreducible anterior dislocations in Epstein's series underwent open reduction, and in this case the iliopsoas tendon was found to be wrapped around the base of the neck, preventing closed reduction.1 In another case, a primary reduction was done and a loose fragment off the superior anterior position of the femoral head was removed before reduction succeeded.1
It is our belief that posterior or lateral approach should not be performed in anterior dislocation because the pathology is invariably anterior,1'3'4 though. Proctor reports one case in which dislocation was accompanied by posterior acetabular rim fracture, which was fixed with screws.5 Most of the authors1'6'7 do agree that anterior dislocation should be approached by anterior Smith-Peterson approach. A meticulous and gentle open reduction should cause no increased incidence of avascular necrosis.
1. Epstein HC: Traumatic dislocation of the hip. Clin Orihop 1973; 92:116-142.
2. Brav EA: Traumatic dislocation of the hip. Army experience and results over a twelve-year period. / Bone joint Surg 1962; 44A:115-134.
3. Mac Parlane JA: Anterior dislocation of the hip. Br j Surg 1936; 33(91 ):607-611.
4. Speed, Kellog: A Textbook of Fractures and Dislocations Covering Their Pathology. Diagnosis and Treatment, ed 4. Baltimore, Williams & Wilkins, 1943.
5. Proctor H: Letter to the editor, iniury 1975; 7(2):lb5-lö6.
6. Amihood S: Anterior dislocation of the hip. iniury 1975; 7(2):107-110.
7. Campbell's Operative Orthopaedics, ed 5. Crewnshaw AH (ed). St. Louis, Mosby, 1971, vol 1.