Dysplasia Epiphysealis Hemimelica of the Acetabulum

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1 Dysplasia Epiphysealis Hemimelica of the Acetabulum A REPORT OF TWO CASES* BY DAVID L. SKAGGS, M.D., CHARLES N. MOON, M.D., ROBERT M. KAY, M.D., LOS ANGELES, CALIFORNIA, AND HAMLET A. PETERSON, M.D., ROCHESTER, MINNESOTA Investigation perfomed at University of Southern California School of Medicine, Childrens Hospital Los Angeles, Los Angeles, and the Mayo Clinic, Rochester Dysplasia epiphysealis hemimelica, which is also known as Trevor disease, is a rare developmental lesion that is histologically identical to an osteochondroma. The more common solitary osteochondroma and multiple hereditary osteochondromatosis typically are located on the metaphysis of long bones, occasionally on the diaphysis of long bones, and on flat bones, but never on the epiphysis. The index lesion is intra-articular and characteristically involves only half of the joint (hemimelic). The osseous portions of the lesion distinguish it from synovial chondromatosis, which always consists of multiple lesions usually dispersed throughout the joint. The osteochondroma of dysplasia epiphysealis hemimelica, in addition to being hemimelic, is initially a solitary lesion, although portions may break off, producing multiple pieces 17. It is typically found in the joints of the lower extremity, with a predisposition for the medial femoral condyle, the distal aspect of the tibia, and the talus 1,2,4,5,7,12,15,21,25. Mouchet and Belot 16, in 1926, were the first to report this entity, and they called it tarsomégalie. Trevor 25 described ten patients in 1950 and used the term tarsoepiphysial aclasis. In 1956, Fairbank 5 reported on fourteen patients and renamed the condition dysplasia epiphysialis hemimelica. We report the cases of two patients who had a subluxation of the hip that was found to be associated with an isolated intra-articular osteochondroma of the acetabulum. These two cases are presented because of the isolated and unique acetabular location of the lesion. Examination revealed mild flexion and abduction contractures of the right hip with complete loss of rotation and a decreased abductionadduction arc, a positive Allis sign, and an abnormal gait. The flexion contracture was 5 degrees, and the abduction contracture was 20 degrees. The gait was abnormal because of these contractures and the absence of internal and external rotation. The lower limbs were of equal length. Radiographs showed a space-occupying lesion located in the ischial and pubic portions of the right acetabulum (Fig. 1-A). A computerized tomography scan confirmed the location of the lesion FIG. 1-A Figs. 1-A through 1-H: Case 1. Fig. 1-A: Anteroposterior radiograph of the right hip, made when the patient was five years and nine months old, showing a lesion in the acetabulum. The image is slightly oblique, and there is slight flattening of the femoral epiphysis. Case Reports CASE 1. A five-year-old girl was referred to one of the authors (H. A. P.) because of a several-month history of bilateral discomfort of the lower limb. The patient s father had noted a change in the child s gait a few days before she was seen by us. The child did not complain of pain in the hip. *No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study. Division of Orthopaedic Surgery, University of Southern California School of Medicine, Childrens Hospital Los Angeles, 4650 Sunset Boulevard, Mailstop 69, Los Angeles, California E- mail address for D. L. Skaggs: dskaggs@chla.usc.edu. Department of Orthopaedic Surgery, University of Southern California Medical Center, 1200 North State Street, GH 3900, Los Angeles, California Mayo Clinic, 200 First Street S.W., Rochester, Minnesota Copyright 2000 by The Journal of Bone and Joint Surgery, Incorporated FIG. 1-B Computerized tomography scan confirming the location of the lesion in the ischial and pubic bones. VOL. 82-A, NO. 3, MARCH

2 410 D. L. SKAGGS, C. N. MOON, R. M. KAY, AND H. A. PETERSON FIG. 1-C Histological section demonstrating a cartilage cap overlying normal bone, which is characteristic of both dysplasia epiphysealis hemimelica and osteochondroma. The cap may be of variable thickness; it tends to be intact in children and to have areas of focal resorption in adults. (Fig. 1-B). There were no other palpable lesions, and none were visible on radiographs of the chest and pelvis. We did not perform a skeletal survey. There was irregular increased radiodensity involving the acetabulum, indicating that the lesion was osteocartilaginous. There were no patchy lytic lesions suggestive of malignancy. An excisional biopsy was performed through an anterior approach. The hip was dislocated so that an excision of the ischial and pubic portions of the tumor could be performed and injury to the triradiate cartilage could be avoided. We believed that dislocating the hip for an hour would not result in any long-term sequelae. To the best of our knowledge, temporary intraoperative dislocation of the hip has not been reported to be associated with avascular necrosis or other hip disability. Furthermore, there was no other way to excise this lesion. The histological findings were consistent with benign osteochondroma (Fig. 1-C), showing a preponderance of large but otherwise normal chondrocytes with an indiscrete border between the cartilage and osseous trabeculae. Postoperative radiographs and computerized tomography scans showed the lesion to have been excised completely. An above-the-knee cast was applied bilaterally, with a bar separating the legs (a simulated A-frame) to keep the hips in mild abduction. Three months after the biopsy, the patient had no pain or limp. The hip lacked the last 25 degrees of internal rotation (measured with the patient in the prone position) in comparison with the contralateral side, and all other ranges of motion were symmetrical with the contralateral side. Three years after the procedure, when the child was nine years old, she was participating in normal activities for her age and was asymptomatic. The Allis and Trendelenburg signs were negative. The gait was normal, and the lower limbs were of equal length. Radiographs showed continued growth and development of both hips, with mild coxa magna and flattening of the medial side of the femoral head on the right (Fig. 1-D). The triradiate cartilage was indistinct, and the thickening of the outer wall of the acetabulum suggested a new lesion (Fig. 1-E). Computerized tomography scans con- FIG. 1-D Anteroposterior radiograph of the pelvis and hips, made three years postoperatively, showing flattening of the femoral head, mild coxa magna, and subluxation. The metaphysis-teardrop distance is increased. The femoral head demonstrates the same flattening seen three years earlier. THE JOURNAL OF BONE AND JOINT SURGERY

3 DYSPLASIA EPIPHYSEALIS HEMIMELICA OF THE ACETABULUM 411 FIG. 1-E Lateral radiograph of the hip, made three years postoperatively, showing the thickened outer wall of the acetabulum suggestive of a new lesion. firmed a recurrent lesion in the depths of the acetabulum (Fig. 1-F). The patient subsequently had another excision performed through an anterior approach. The hip was again dislocated to facilitate the approach; the lesion was resected, and histological findings confirmed it to be osteochondroma. Eight years after the second procedure, when the patient was seventeen years and nine months old, she was participating in sports with no pain or limp. Internal and external rotation of the right hip lacked 10 degrees compared with the left hip, but other motions were equal and symmetrical. Radiographs showed excellent remodeling of the acetabulum, with complete filling of the defect (Figs. 1-G and 1-H). There was some persistent, mild asymmetry of the femoral head. CASE 2. A seven-year-old girl was first seen at another institution because of a two-month history of discomfort of the right hip that did not respond to nonsteroidal anti-inflammatory drugs. The initial radiographs showed only subluxation of the right hip, with no other pathological lesion noted. A bone scan demonstrated increased uptake in the right acetabulum. The differential diagnosis of an infection of the hip joint or transient synovitis was considered likely, with the effusion thought to be the cause of the hip subluxation. An aspiration of the hip was performed with fluoroscopic control, followed by open incision and drainage of the hip through a posterior approach. We believe that the findings were not sufficient to warrant the open drainage and would have proceeded with imaging studies to assess the lesion. The gram stain and the cultures were negative. There were no systemic symptoms, and the hip remained subluxated. Magnetic resonance imaging was then performed and interpreted as showing an excess of fluid displacing the hip laterally. In retrospect, an acetabular mass was noted on the imaging studies. Two weeks after the incision and drainage of the hip, the patient was referred to one of the authors (D. L. S.) for treatment of subluxation of the right hip. She reported continued activity-related pain in the right hip. On physical examination, there was a positive Galeazzi sign. Internal rotation of the affected right hip, measured with the patient in the prone position, was 10 degrees, compared with 45 degrees on the left, with a 10-degree loss of extension of the right hip. The patient walked with a mild antalgic gait and had a positive Trendelenburg sign. Plain radiographs confirmed hip subluxation and showed the right acetabulum to have an increased density suggestive of a spaceoccupying lesion. A preliminary diagnosis of Trevor disease was made. Computerized tomography scans with cuts made, at 1.5-millimeter intervals, through the acetabulum revealed an osseous growth from the acetabulum and subluxation of the hip. No other lesions were found clinically or on radiographs of the lower extremities. The hip was opened through an anterior approach, and the femoral head was dislocated. The cartilaginous surface of the mass was inflamed with hypertrophic tissue consistent with the appearance of an inflammatory response. On palpation, the lesion was continuous with and fixed to the acetabulum. This lesion was removed with rongeurs and high-speed burrs, with care taken to avoid the triradiate cartilage. The diagnosis of dysplasia epiphysealis hemimelica was confirmed by analysis of frozen and permanent sections. The femoral head had evidence of mild, abnormal wear in the posterior-inferior portion. Postoperatively, the patient wore an abduction orthosis for nine weeks, although full weight-bearing was permitted. At the time of the two-year follow-up evaluation, she had a full, painless range of motion of the hip and reported no problems. A follow-up computerized tomography scan showed evidence of acetabular remodeling with no evidence of recurrence. There was no sign of avascular necrosis of the femoral head. Permanent histopathological sections were reviewed by the hospital staff and independently by pathologists with expertise in orthopaedic pathology at two outside facilities. The final histological diagnosis was dysplasia epiphysealis hemimelica. Discussion In 1950, Trevor 25 presented a description of a congenital growth disorder of the tarsus and of the epiphyses. The lesion that he described involved the talus, both malleoli, the navicular, and all of the cuneiform bones. In his report, which provided the first known Englishlanguage description of epiphyseal osteochondroma, Trevor described eight pediatric patients in whom the predominant joint of involvement was the ankle. He believed that the lesion was congenital and that the etiology was related to an insult during the formation of the limb bud. In 1956, Fairbank 5 reviewed Trevor s cases, presented two of his own, and coined the term dysplasia epiphysialis hemimelica to better describe the findings. He believed the process to be a true dysplasia or faulty growth of part of the epiphysis itself. Wynne-Davies 27 reported a prevalence of one per FIG. 1-F Computerized tomography scan, made three years postoperatively, confirming the presence of a recurrent lesion in the same region. The patient subsequently had another operative procedure. VOL. 82-A, NO. 3, MARCH 2000

4 412 D. L. SKAGGS, C. N. MOON, R. M. KAY, AND H. A. PETERSON FIG. 1-G Anteroposterior radiograph of the pelvis and hips, made eight years after the second operation, showing acetabular remodeling, some sclerosis and irregularity, and mild asymmetry of the femoral head corresponding to the previous flattening of the femoral head. million but did not provide the numerical basis of this prevalence. Males are affected more often than females, in a ratio of 3:1 23,27. Hensinger et al. 10 reported on a family with a hereditary pattern of cartilage tumors, including Trevor lesions, but the disease does not appear to be genetically transmitted in general 4,10,11,23. Hensinger et al. reported on seven family members with combinations of dysplasia epiphysealis hemimelica, intracapsular chondroma, extraskeletal osteochondroma, and typical osteochondroma. Six of the seven family members had a dysplasia epiphysealis hemimelica lesion. Six of the seven patients had operative treatment for the symptomatic lesions. There were no recurrences. The dysplasia epiphysealis hemimelica lesions involved the wrist in three family members, the foot in two, and the knee in one. To the best of our knowledge, no cases of malignant transformation have been reported 2,6,10,11,20,23. The condition is characterized by a lesion of the epiphysis or the tarsal or flat bones, typically in a single lower extremity. Two cases with a bilateral lesion have been reported 8,24. The ankle is most commonly affected. Recently, cases involving the upper extremity have been described 4,14,19. Cruz-Conde et al. 4 described a boy who had severe involvement of the left side of the body, including the shoulder, elbow, and wrist. Rao and Roy 19 managed a patient who had a lesion in the capitellum and the distal aspect of the ulna. Lamesch 14 reported on a patient who had involvement of the wrist, affecting the scaphoid, the trapezium, and the distal aspect of the radius. There may be a single lesion or multiple lesions; two-thirds of patients have multiple lesions 2,14,19,23,27. The lesions typically affect only one side of the joint, either medial or lateral, although there has been a report of asymmetrical involvement 9. The findings on radiographs have been well described in multiple reports 1,2,22. The lesion often is not visible on plain radiographs, as it may not have begun ossification. Once mineralization has begun, it appears as ossification at the secondary ossification center. The histological appearance of this lesion, a well defined cartilage cap over projecting bone that is continuous with the underlying normal bone, is indistinguishable from that of an osteochondroma. We know of only one other case of an isolated osteochondroma of the acetabulum in the English-language literature 3. A thirteen-year-old boy was seen because of a three-month history of occasional discomfort in the hip and a limp. An acetabular lesion was noted on a FIG. 1-H Lateral radiograph, made eight years after the second operation, showing narrowing of the joint space and irregularity of the femoral head. THE JOURNAL OF BONE AND JOINT SURGERY

5 DYSPLASIA EPIPHYSEALIS HEMIMELICA OF THE ACETABULUM 413 radiograph. The tumor was excised, and the gross and histological findings were consistent with those of an osteochondroma. No follow-up data were reported. We are aware of two case reports of a lesion in the hip that involved both the acetabulum and the femoral head. In both cases, the involvement of the femoral head was much greater than that of the acetabulum, was obvious, and appeared to be the reason for the poor outcome. Cruz-Conde et al. 4 reported severe involvement on the left side, with changes in the femoral head. Mendez et al. 15 reported on a patient who had isolated involvement of the hip. In both of these patients, the entire femoral head was involved, which precluded a good outcome. Recently, Woodward et al. 26 documented the cases of two children who had multiple hereditary osteochondromatosis and a painful limp with subluxation of the hip due to acetabular osteochondromas. Excision of the tumors without dislocation of the hips resulted in satisfactory short-term results three and fourteen months later. The presence of multiple osteochondromas aroused suspicion of similar intra-articular lesions in the hip and increased the likelihood of an accurate preoperative diagnosis. The decision whether to classify the isolated acetabular tumors reported here as dysplasia epiphysealis hemimelica or as solitary osteochondromas is a speculative one, as the histopathological features of the two lesions are identical. Solitary osteochondromas typically arise from the metaphysis, and many do not cause symptoms sufficient to warrant operative intervention. Since the two patients in the present report had only one lesion (distinguishing the condition from multiple hereditary osteochondromatosis), we classified the lesions as dysplasia epiphysealis hemimelica because of their intra-articular location. Other authors have used similar reasoning to classify an osteochondroma of the sacroiliac joint as dysplasia epiphysealis hemimelica 2. The symptoms in these children and those in the child previously reported on by Bleshman and Levy 3 are similar. Each child had relatively mild discomfort, accompanied by a limp and nearly normal gait, for months. For two of the patients, the correct diagnosis was not made initially, and, in one of our patients, an unnecessary operation was performed before the correct diagnosis was made. The intra-articular position of dysplasia epiphysealis hemimelica lesions plays a crucial role in the symptoms, prognosis, and treatment. The treatment of dysplasia epiphysealis hemimelica may be controversial, depending on the location of the lesion. Some authors have recommended against excision of articular lesions 13. Since the subluxated hips of the children in our report were already symptomatic, we believe excision of the tumor was necessary to prevent progressive hip problems in the future, as has been previously reported 3,26. Kuo et al. 13 also believed that juxta-articular symptomatic lesions should be excised. They did not recommend excision of articular lesions because it is technically difficult, it further compromises the joint, and it increases the risk of degenerative arthritis. Woodward et al. 26 reported subluxation of the hip in patients who had multiple osteochondromatosis. Their patients were similar to our patients, but their patients had multiple hereditary osteochondromatosis. Both of their patients had a resection of the lesion, to prevent dislocation of the hip, and were reported as doing well in the short term. Whether it is necessary to dislocate the hip is speculative and depends on the location and size of the mass. Visualization of the tumor and avoidance of damage to the triradiate cartilage are critical intraoperative concerns. Although Woodward et al. 26 resected acetabular osteochondromas without dislocation of the femoral head, their patients were followed for only three and fourteen months. Recurrence is still possible after that amount of time, as was noted in one of our patients three years after excision of the tumor. There were no sequelae after intraoperative dislocation of the hip in the two patients in the present report. One patient had the hip dislocated twice and was followed to maturity. There was excellent remodeling of the acetabulum and a viable femoral head; the joint space was minimally narrowed. We therefore would not hesitate to dislocate the hip in future patients to obtain good visualization. We believe that without intervention the end result would have been worse. References 1. Abrahams, T. G.; Whitten, C. G.; Jones, M.; and Dorfman, H. J.: Case report 632. Parosteal osteochondromatous hamartoma associated with Trevor s disease (dysplasia epiphysealis hemimelica). Skel. Radiol., 20: 47-52, Azouz, E. M.; Slomic, A. M.; Marton, D.; Rigault, P.; and Finidori, G.: The variable manifestations of dysplasia epiphysealis hemimelica. Pediat. Radiol., 15: 44-49, Bleshman, M. H., and Levy, R. M.: An unusual location of an osteochondroma. Radiology, 127: 456, Cruz-Conde, R.; Amaya, S.; Valdivia, P.; Hernandez, M.; and Calvo, M.: Dysplasia epiphysealis hemimelica. J. Pediat. Orthop., 4: , Fairbank, T. J.: Dysplasia epiphysialis hemimelica (tarso-epiphysial aclasis). J. Bone and Joint Surg., 38-B(1): , Fasting, O. J., and Bjerkreim, I.: Dysplasia epiphysealis hemimelica. Acta Orthop. Scandinavica, 47: , Graves, S. C.; Kuester, D. J.; and Richardson, E. G.: Dysplasia epiphysealis hemimelica (Trevor disease) presenting as peroneal spastic flatfoot deformity: a case report. Foot and Ankle, 12: 55-58, Gregory, P. R., Jr., and Rooney, R. J.: Bilateral dysplasia epiphysealis hemimelica: a case report. Foot and Ankle, 14: 35-37, Heilbronner, D. M.: Asymmetric dysplasia epiphysealis hemimelica. Orthopedics, 11: , Hensinger, R. N.; Cowell, H. R.; Ramsey, P. L.; and Leopold, R. G.: Familial dysplasia epiphysealis hemimelica, associated with chondromas and osteochondromas. Report of a kindred with variable presentations. J. Bone and Joint Surg., 56-A: , Oct VOL. 82-A, NO. 3, MARCH 2000

6 414 D. L. SKAGGS, C. N. MOON, R. M. KAY, AND H. A. PETERSON 11. Keret, D.; Spatz, D. K.; Caro, P. A.; and Mason, D. E.: Dysplasia epiphysealis hemimelica: diagnosis and treatment. J. Pediat. Orthop., 12: , Kettelkamp, D. B.; Campbell, C. J.; and Bonfiglio, M.: Dysplasia epiphysealis hemimelica. A report of fifteen cases and a review of the literature. J. Bone and Joint Surg., 48-A: , June Kuo, R. S.; Bellemore, M. C.; Monsell, F. P.; Frawley, K.; and Kozlowski, K.: Dysplasia epiphysealis hemimelica: clinical features and management. J. Pediat. Orthop., 18: , Lamesch, A.: Dysplasia epiphysealis hemimelica of the carpal bones. Report of a case and review of the literature. J. Bone and Joint Surg., 65-A: , March Mendez, A. A.; Keret, D.; and MacEwen, G. D.: Isolated dysplasia epiphysealis hemimelica of the hip joint. A case report. J. Bone and Joint Surg., 70-A: , July Mouchet, A., and Belot, J.: La tarsomégalie. J. radiol. électrol., 10: , Noyes, F. R., and Kivi, L. P.: Dysplasia epiphysealis hemimelica. A case simulating an intra-articular body. Clin. Orthop., 86: , Peterson, H. A.: Multiple hereditary osteochondromata. Clin. Orthop., 239: , Rao, S. B., and Roy, D. R.: Dysplasia epiphysealis hemimelica. Upper limb involvement with associated osteochondroma. Clin. Orthop., 307: , Schmidt, M. B., and Lomasney, L. M.: Radiologic case study. Trevor disease: dysplasia epiphysealis hemimelica. Orthopedics, 17: , Segal, L. S.; Vrahas, M. S.; and Schwentker, E. P.: Dysplasia epiphysealis hemimelica of the sacroiliac joint. A case report. Clin. Orthop., 333: , Silverman, F. N.: Dysplasia epiphysealis hemimelica. Sem. Roentgenol., 24: , Tachdjian, M. O.: Dysplasia epiphysealis hemimelica. In Pediatric Orthopedics. Ed. 2, vol. 2, pp Philadelphia, W. B. Saunders, Takegami, Y., and Nogami, H.: A case of bilateral dysplasia epiphysealis hemimelica associated with polydactyly and syndactyly. Clin. Orthop., 296: , Trevor, D.: Tarso-epiphysial aclasis. A congenital error of epiphysial development. J. Bone and Joint Surg., 32-B(2): , Woodward, M. N.; Daly, K. E.; Dodds, R. D. A.; and Fixsen, J. A.: Subluxation of the hip joint in multiple hereditary osteochondromatosis: report of two cases. J. Pediat. Orthop., 19: , Wynne-Davies, R.: Dysplasia epiphysealis hemimelica. In Atlas of Skeletal Dysplasias, pp Edinburgh, Churchill Livingstone, THE JOURNAL OF BONE AND JOINT SURGERY