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© 1999 The Journal of Bone and Joint Surgery, Inc. Avulsion Fracture of the Lesser Trochanter as a Result of a Primary Malignant Tumor of Bone. A Report of Four Cases*  , LOS ANGELES, CALIFORNIAInvestigation performed at the Department of Orthopaedic Surgery, University of California at Los Angeles School of Medicine, Los Angeles
A review of the current literature identified two primary causes of avulsion of the lesser trochanter: strenuous flexion of the hip in adolescent athletes with open epiphyses2,5-9,11,15,16 and pathological fracture associated with a metastatic lesion of bone3,14. In both cases, stress concentration at the site of the iliopsoas muscle leads to a tensile failure of either the apophysis or the lesser trochanter. Typically, the force necessary to avulse an otherwise normal apophysis is much greater than that required to produce a pathological fracture, and the latter mechanism is rarely associated with a history of trauma20. We report the cases of four patients who had an avulsion fracture of the lesser trochanter secondary to a primary malignant tumor of bone. To our knowledge, this is the first report in which a pathological fracture of the lesser trochanter was the presenting symptom leading to the diagnosis of such a tumor. In the absence of a traumatic event, an isolated fracture of the lesser trochanter should suggest an underlying pathological process, particularly a primary or metastatic tumor. To avoid inappropriate operative procedures, a pathological diagnosis must be made by means of a biopsy before internal fixation is attempted.
CASE 1. A forty-four-year-old man was first seen by us in June 1985 because of a two-week history of pain in the left hip without antecedent trauma. The pain had been insidious in onset and was aggravated by flexion of the hip. The patient had noted an acute worsening of the pain while sailing. At the time of presentation, he also reported pain in the groin and weakness in the left lower extremity. Clinical examination demonstrated weakness and an inability to flex the left hip against resistance secondary to pain. Radiographs revealed a pathological fracture of the lesser trochanter and a large lytic lesion involving the intertrochanteric region of the femoral metaphysis (Fig. 1). Computed tomography showed the process to be confined primarily to the lesser trochanter, with no soft-tissue extension. A technetium-99 bone scan and a skeletal survey did not reveal any other lesion, and the workup for myeloma was negative. The results of a biopsy were consistent with a diagnosis of a solitary plasmacytoma. The patient was managed with prophylactic fixation with use of a Zickel nail and methylmethacrylate cement in 1985. An extensive postoperative workup, which included immunoprotein electrophoresis and bone-marrow biopsies, did not demonstrate the presence of the more diffuse condition of multiple myeloma. Postoperatively, the patient was managed with irradiation of the hip and the proximal aspect of the femur. At the time of the most recent follow-up, in April 1998, the left lower limb remained asymptomatic, the reconstruction was intact, and there was no evidence of either recurrence of the solitary plasmacytoma or progression to multiple myeloma.
CASE 2. A sixty-nine-year-old man was seen at another institution in November 1987 because of the insidious onset of pain in the left part of the groin. There was no history of trauma or strenuous activity. The patient initially was diagnosed as having a muscle strain and was managed with nonsteroidal anti-inflammatory drugs. The patient continued to have increasing pain and difficulty with lifting the lower extremity and, in April 1988, he sustained an avulsion fracture of the lesser trochanter while getting out of his automobile. Radiographs made at the other institution showed a pathological fracture of the lesser trochanter, widening of the medullary canal in the intertrochanteric region, areas of radiolucency and increased radiodensity in the medullary canal, and thickening of the cortex medially; these findings were suggestive of a chondrosarcoma (Fig. 2-A). Magnetic resonance imaging demonstrated a large soft-tissue extension of the tumor (Fig. 2-B). A technetium-99 bone scan revealed the lesion to be localized to the proximal aspect of the left femur. The importance of these radiographic findings was not appreciated, and it was assumed that the lesion was metastatic. The fracture was treated with open reduction and internal fixation in May 1988 (Fig. 2-C). A biopsy done at the time of this procedure revealed a chondrosarcoma.
When the patient was first seen at our institution, he declined to have a hemipelvectomy. This procedure was recommended because the previous operation had been performed by a general orthopaedic surgeon who had not recognized the lesion as a primary malignant bone tumor and we were concerned that there might be extensive local contamination. A preoperative computed tomography scan of the chest did not reveal any evidence of metastatic disease. In July 1988, the patient had a wide en bloc resection of the proximal 27.5 centimeters of the femur and adjacent muscles followed by reconstruction with a custom-designed proximal femoral endoprosthesis. By May 1990, he had had both local recurrence (treated with resection) and pulmonary metastasis (treated with two thoracotomies). The patient died in May 1991 following a massive stroke; he had pulmonary metastases at the time of death. CASE 3. A nineteen-year-old man was seen at another institution in the fall of 1985 because of pain in the right side of the groin with no specific antecedent trauma. Chiropractic manipulations provided no relief. A few weeks later, he felt and heard a loud crack in the right side of the groin while stepping onto a curb. Radiographs made at that time revealed a pathological fracture of the lesser trochanter. An attempt to fix the fracture with a Ludloff approach was aborted for reasons that are not known. A biopsy of material obtained during that procedure was nondiagnostic. When the patient was first seen in our institution in December 1985, there was massive swelling of the right buttock and the entire proximal half of the right thigh. Repeat radiographs (Fig. 3) and a computed tomography scan demonstrated a permeative, destructive lesion of the proximal aspect of the right femur, with massive soft-tissue involvement of all compartments of the right thigh and buttock, and a pathological fracture of the lesser trochanter. An open biopsy was diagnostic for Ewing sarcoma. The patient was managed preoperatively with adjuvant chemotherapy and radiation therapy. In February 1986, he had a wide resection followed by reconstruction with use of a custom-designed proximal femoral component. The patient returned with widespread osseous and pulmonary metastasis within two months after this limb-sparing operation and died six months later.
CASE 4. A thirty-six-year-old man who had a two-year history of low-back pain and posterolateral radiculopathy of the left lower extremity following excision of a disc was first seen by us in March 1994 because of new symptoms of pain in the left side of the groin and weakness of flexion of the hip. Radiographs showed a pathological fracture of the left lesser trochanter (Fig. 4-A), and magnetic resonance imaging revealed a large soft-tissue extension (Fig. 4-B). A biopsy performed under the guidance of computed tomography in April 1994 confirmed the diagnosis of a high-grade chondrosarcoma. A wide resection followed by reconstruction of the proximal aspect of the femur with an allograft-prosthesis composite was performed immediately. The patient subsequently had resection of metastatic nodules. At the time of the latest follow-up, he had had no additional evidence of either local recurrence or metastatic disease for two years.
In patients who have open epiphyses, an avulsion fracture of the lesser trochanter is usually secondary to vigorous activity. This type of fracture typically occurs during adolescence. It usually is seen between the ages of seven and sixteen years2,6-8 and most commonly occurs at the age of fourteen years. Theoretically, the upper age-limit for an avulsion fracture of the lesser trochanter secondary to vigorous activity is eighteen or nineteen years, by which time there is fusion of the lesser trochanteric apophysis17. The literature is replete with reports of this mechanism of injury2,5-9,11,15,16. To the best of our knowledge, only two groups of authors have explicitly discussed fracture of the lesser trochanter in conjunction with neoplasm, and in all patients the fracture was the first sign of metastatic disease. Bertin et al.3 and Phillips et al.14 both described four patients who had a fracture of the lesser trochanter and previously undiagnosed metastatic disease involving the proximal aspect of the femur. In those two small series, no particular neoplasm appeared to be more prone than any other lesion to cause an avulsion of the lesser trochanter. Although breast cancer is the most common neoplasm to metastasize to bone and has been reported to cause approximately one-half of all neoplastic pathological fractures1,18, it has not been identified as the underlying cause of a pathological avulsion fracture of the lesser trochanter, to our knowledge. As far as we know, we are the first to describe avulsion of the lesser trochanter as the presenting symptom leading to the diagnosis of a primary malignant tumor. The present report describes four patients who had an avulsion fracture of the lesser trochanter secondary to a primary malignant bone tumor (a sarcoma in three patients and a solitary plasmacytoma in one). However, it is well known that a pathological fracture through a primary malignant tumor may be the presenting symptom or may occur during the course of preoperative neoadjuvant treatment21. These fractures tend to occur in the metaphysis or diaphysis of the humerus or femur rather than presenting as avulsion fractures of the lesser trochanter. Plasmacytoma is a primary malignant bone tumor that is histologically identical to multiple myeloma10. Knowling et al. considered the solitary plasmacytoma to be an early form of multiple myeloma, with eventual progression to multiple-site involvement being the rule12. This understanding of the natural progression of plasmacytoma to multiple myeloma is shared by orthopaedic oncologists and pathologists4,13,19. In the present report, the patient who had a solitary plasmacytoma of the intertrochanteric area of the femur did not have progression to multiple myeloma during the thirteen-year period of postoperative observation. Close scrutiny of the initial radiographs of all of the patients in the present report demonstrated a destructive lesion or pathological process that involved the proximal part of the femur in addition to the more obvious fracture of the lesser trochanter. The presenting symptoms of a fracture of the lesser trochanter, regardless of etiology, include pain in the groin and pain-induced weakness of flexion of the hip when tested with the patient in the supine or standing position. When there is no history of trauma, the presence of a destructive lesion on radiographs should lead to suspicion of an underlying pathological process but cannot be assumed to be evidence of metastatic disease. Appropriate diagnostic studies include plain radiography, technetium-99 bone-scanning, and magnetic resonance imaging or computed tomography, or both. If myeloma or plasmacytoma is considered in the differential diagnosis before the biopsy, immunoprotein electrophoresis should be performed along with the usual chemistry panels, hematological studies, and measurement of the erythrocyte sedimentation rate. A carefully planned open biopsy or a closed biopsy performed under the guidance of computed tomography should be done by an individual who is knowledgeable in the treatment of primary malignant bone tumors in order to avoid delaying the diagnosis or complicating a possible limb-salvage procedure. Two of the four patients in the present report had inappropriate and premature operative procedures. In the first patient (Case 2), the assumption that the fracture was due to metastatic disease led to a conventional open reduction and internal fixation procedure. The diagnosis of primary chondrosarcoma was established only after the fact. Extensive contamination of the surrounding tissues placed the patient at increased risk for local recurrence, which did in fact occur. In the second patient (Case 3), failure to adequately assess the cause of the lesser trochanteric avulsion resulted in an aborted attempt to fix the fracture through an inappropriate incision and, consequently, a delay in the proper diagnosis. In contrast to traumatic or exercise-induced avulsion fractures, pathological fractures secondary to metastatic disease have been reported to occur over a wide range of ages (eighteen to seventy years3,14). The patients in the present report were nineteen, thirty-six, forty-four, and sixty-nine years old. In all four patients, the clinical presentation of the lesion was similar to that of a metastatic tumor in that it was characterized by a sudden or insidious onset of pain in the groin without antecedent acute trauma or strenuous exercise. The history is therefore critical in the differentiation between traumatic and pathological avulsion fractures of the lesser trochanter. As both conditions are associated with similar clinical findings, including pain and weakness with attempted flexion of the hip, radiographs must be carefully scrutinized to determine if there is an underlying pathological process. A full workup, including a carefully planned biopsy, is necessary to differentiate a metastatic malignant tumor from a primary malignant tumor. Accurate distinction between these two conditions is critical because the methods of operative treatment are drastically different. In conclusion, one must be wary of several factors when evaluating a patient who has separation of the lesser trochanter from the proximal aspect of the femur. Distinction between apophyseal avulsion of the lesser trochanter and pathological fracture through the lesser trochanter entails a detailed workup that must include consideration of age, medical history, the mechanism of injury, and the shape of the lesser trochanteric fragment on radiographs. Additional ancillary studies should be performed, when appropriate, to detect the presence of a neoplasm. If the fracture is atraumatic and has occurred in an adult, the physician must include the possibility of a primary or metastatic tumor in the differential diagnosis. In addition to a pathological fracture through an existing metastatic lesion, one must consider the possibility of a primary malignant bone tumor. To avoid an inappropriate operative procedure, a pathological diagnosis must be made by means of a biopsy before internal fixation is attempted.
*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.
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