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A 65-year-old man with osteoarthritis of the hip underwent a cementless total hip replacement with a modern generation, metal-on-metal bearing. Two years later the patient presented with localized osteolysis at the tip of the femoral stem. At the time of revision, the stem was found to be well-fixed. Extensive analyses of the bearing surfaces and periprosthetic tissues were done. There was minimal bearing surface wear and only small numbers of inflammatory cells, such as macrophages, in the tissues, and it was concluded that this was not a typical case of particle-induced osteolysis. All cultures and laboratory studies were negative for infection. This case report supports the multifactorial nature of osteolysis, which includes the osteolytic potential of joint fluid access to and fluid pressures within, the effective joint space.

The periprosthetic tissue reaction to polyethylene wear debris in metal on polyethylene total hip replacements is strongly implicated as the cause of osteolysis. This has led to a renewed interest in metal on metal total hip replacements. However, little is known about the role of wear debris in failures of these prostheses. Capsular and interface tissues from 9 long and short term metal on metal total hip replacement retrievals were studied to assess the tissue reaction around these prostheses. As compared with metal on polyethylene cases, the extent of the granulomatous inflammatory reaction and the presence of foreign body type giant cells was much less intense in metal on metal cases, likely because of the lower numbers and overall smaller size of metal wear debris particles. This may lead to a better transport of the particles from the joint tissues and a lower incidence of periprosthetic osteolysis around metal on metal hip replacement.

Retinoblastoma, though uncommon, frequently is associated with other second malignant neoplasms, especially bone sarcomas. These second neoplasms can occur in sporadic cases of retinoblastoma, though they more commonly are associated with genetic forms of the disease. This is the first known report of 2 histologically distinct bone sarcomas in a patient with retinoblastoma.

Pigmented villonodular synovitis is a well-described disease that almost universally involves a single site. This is a report of an unusual case of multiple site involvement of pigmented villonodular synovitis in a child. In addition to multiple site involvement, the case is unusual for several reasons: asymmetric involvement, involvement of both upper and lower extremities, involvement of the pes anserine tendons, and the patient is an otherwise healthy child.

Benign giant cell tumor of bone, despite being classified as benign, has the unusual ability to metastasize. Metastasis of such a tumor has been thought to be rare, with only approximately 50 such cases having been reported. However, as awareness of the metastatic potential of these tumors has increased, and methods of detection have improved, metastasis of benign giant cell tumor has been increasingly recognized. Six patients with pulmonary metastasis of giant cell tumor have been treated at a Los Angeles hospital since 1980. This represents 9.1% of all patients treated for benign giant cell tumor of bone over the same period at this institution, a higher rate than that encountered in previously published series. The early detection and treatment of this tumor is important, because those with complete resection of tumor have the best prognosis. The nature of these pulmonary metastases remains unpredictable, however, as evidenced by two of the cases in this series: one of spontaneous regression, and another of death caused by pulmonary failure.

In 27 patients with extremity lesions (24 osteosarcoma, three malignant fibrous histiocytoma), a notable decrease in thallium-201 uptake was correlated with a good response to preoperative chemotherapy of the primary tumor. A good response is indicated by a greater than 95% tumor necrosis. Serial quantitative thallium-201 uptake of malignant bone tumors in patients receiving preoperative chemotherapy therefore can accurately predict a good histologic response and prognosis. Serial thallium scintigraphy can furthermore identify poor responses within two weeks after the initiation of treatment, or can prompt an early change in preoperative chemotherapy and facilitate limb salvage surgery.

Wide excision, a recommended treatment for osteoid osteoma, creates needless resection of surrounding bone and causes difficult intraoperative nidus identification. Less bone resection is required by successively burring through the reactive bone to identify the nidus, which is then removed with curettes and burrs. This burr-down technique requires precise preoperative anatomic localization by thin section (1-1.5 mm) computed tomography (CT) scans. In a consecutive series of 19 osteoid osteomas, 18 were accurately diagnosed before operation, using a combination of clinical findings, plain roentgenograms, and CT scans. The burr-down technique was successfully used in 15 cases, and four were treated with wide excision. There have been no local recurrences. The follow-up period for all 19 patients was at least six months. No bone grafts were required in the burr-down group in nonspinal locations; there have been no fractures despite early return to unrestricted activity. The burr-down technique was associated with less postoperative immobilization, a shorter duration of protected weight bearing, and an earlier return to activity. The burr-down technique is recommended for accessible osteoid osteoma lesions.

Over an eight-year period, 100 patients with IIB osteosarcoma have been managed. Eighty-one were treated with limb-salvage procedures, 78 of which involved reconstruction utilizing endoprostheses. Only 19 patients received amputation as the primary treatment for local control. Since 1984, all patients received preoperative and post-operative adjuvant chemotherapy. Those patients who received chemotherapy had a statistically significant improvement in five-year survival over those who did not (57% and 32%, respectively, p = 0.014). The functional results were good overall, with excellent results seen in distal femoral reconstruction. Twenty-eight of the 78 patients treated with endoprosthetic reconstruction experienced 30 complications (36%). Mechanical failure was the most common complication (10%) but was generally correctable. The local recurrence rate was 5% and the infection rate was 3%. Local complications were manageable. A statistical analysis revealed that the relative risk of patient death was 2.5 times higher than prosthesis failure for the 78 patients with endoprosthetic reconstruction. The intermediate-term results, with a median follow-up period of 43 months, remains encouraging.

A 73-year-old patient with Paget's disease of bone was found to have associated diffuse pigmented villonodular synovitis (PVNS) of the right knee joint. Paget's disease has been reported in association with bone sarcoma, benign giant-cell tumor of bone, myeloma and a single case of giant-cell tumor of tendon sheath. the tendency for Paget's disease to be associated with giant-cell-rich lesions of bone and joint, which includes PVNS, merits further investigation, particularly since the recent observation of intranuclear viral-like inclusions in the osteoclast of all patients with this disease.

A microscopic ectopic remnant of notochord and hyaline cartilage was an incidental autopsy finding within a vertebral body. Such ectopic notochordal vestiges have been hypothesized to be the origin of vertebral chordomas, but very few have ever been reported. Whereas ectopic notochord has been demonstrated regularly in the spheno-occipital region (in both embryos and adults) and in the sacrococcygeal region (in embryos), the occurrence of such tissue rests in other segments of the vertebral column is extremely rare. The possible relationship of ectopic vertebral notochordal rests to associated hyaline cartilage formation and to vertebral chordomas requires further investigations.

A 17-year-old female presented with a large, destructive, giant-cell tumor of the second cervical vertebra. The lesion was obviously life-threatening. Owing to its proximity to the spinal cord and the danger of a pathologic fracture with cord transection and because of the effectiveness of cryosurgical methods in treating giant cell tumors of long bones, we decided to attempt local freezing of the lesion using a cryoprobe via a transoral approach. To further ensure tumor destruction, we followed cryosurgery with a course of radiotherapy (4600 rads). At this writing, 30 months later, healing has been excellent with no signs of recurrence, pain, tenderness or neurologic problems. To the best of our knowledge, this represents the first time a vertebral body bone tumor has been treated by cryosurgery.

In 94 cases of failed total hip and knee joint arthroplasties, acute and chronic inflammation, acrylic, metal, and polyethylene debris, and histiocytic reaction were assessed in a 0, 1+, 2+, 3+ semiquantitative manner. Chronic inflammation of 2+ to 3+ was not particularly useful in separating a reaction to wear debris from infection. At the time of frozen section, 2+ to 3+ acute inflammation (greater than 5 PMNs per high power field) was used with excellent follow-up bacteriologic correlation to delay replacement of the failed prosthesis until the infection was controlled. Acrylic (2+ to 3+) and excessive polyethylene wear debris correlated well with loosening. Dusky grey cells were the hallmark of metal-filled histiocytes. Mononuclear and multinuclear histiocytes (2+ to 3+) were correlated with excessive acrylic and/or polyethylene debris. The histologic features of metal particles, acrylic voids, polyethylene and teflon fibers and silastic globules illustrate the pathologic identification of these materials.

This is a 3-year follow-up report of an eosinophilic granuloma of bone occurring in a growing epiphysis. The lesion occurred in a 6-year-old boy and is only the third such case reported in the literature. Eosinophilic granuloma should be considered in the differential diagnosis of lytic lesions of the epiphysis in childhood.

An osteoid osteoma, excised from the neck of the femur of a 23-year-old man, was cut into four 1.5 mm3 fragments and immediately transplanted into muscle pouches in athymic nude mice. One fragment was devitalized by lyophilization before implantation. The viable tumor cell xenografts grew, differentiated into uncalcified osteoid, and retained the characteristics of the original tumor. The killed implants were resorbed, but both the surviving viable and nonviable tumor tissue induced the connective tissue cells of the mouse host bed to proliferate and differentiate into normal cartilage and calcified bone. The mouse new bone deposits were remodeled and colonized by bone marrow, a tissue not seen in osteoid osteomas. These observations suggest that the sclerotic bone shell characteristic of osteoid osteomas may be an inductive reaction of host bed tissue to an osteoma cell product that is comparable to bone morphogenetic protein (BMP) produced by normal bone cells and transferred by normal bone matrix.

Magnetic resonance (MR) images were correlated with matched histologic sections of a resected ischemic necrotic femoral head and neck. Preoperative radiographs had revealed Stage 3 ischemic necrosis. Preoperative MR images disclosed foci of abnormally low signal intensity alternating with normal-appearing foci of high signal intensity. Surgical resection of the femoral head and neck was followed by MR imaging and pathologic sectioning, fixation, and staining, enabling the individual sections to be compared with the postoperative MR slices. A subchondral focus of diminished signal intensity was shown to represent saponified fat and consisted of a transudate of proteinaceous material with probable calcifications. The subjacent region of normal, high signal intensity represented "mummified" fat. The next lower stratum of diminished signal intensity was composed of fibrous and vascular tissues and histiocytic infiltrates that had extensively or completely replaced the fatty marrow.

A case of giant cell tumor (GCT) of the distal femur in a 56-year-old man is reported in association with Paget's disease. The case is unique in that is is the first report of GCT arising in a patient with this disease in which the neoplasm arose in a bone that did not show radiologic evidence of Paget's disease. This case also represents the first example of such an association in which viral-like inclusion bodies are seen in the osteoclast of the tumor. The fact that similar inclusion bodies are seen in the osteoclast of patients with Paget's disease and in their GCT implies a cause-and-effect etiologic relationship rather than mere coincidence. The implications are that a slow-virus infection is involved in the pathogenesis of Paget's disease and in giant cell tumors occurring in patients with this disease.

Thirty-four hip and knee total arthroplasty failures due to infection, loosening, intractable pain and dislocation were examined for synovial and capsular tissue debris. Simiquantitative assessments were made for metal polyethylene, acrylic and cellular debris and inflammation. The most important finding was that in the amounts normally shed into joints, debris particles do not appear to stimulate a polymorphonuclear response. The magnitude of this response correlates best with clinical and/or bacteriological evidence of infection. The quantity of acrylic particles could be correlated with clinical evidence of loosening. Since the correlation between infection and polymorphonuclear leukocytes, debris particles, and the reasons for failure is high, frozen section may aid the surgeon in determining the methods and timing of revision operations.

It has been slightly over 100 years since Sir James Paget's classic descriptions of "osteitis deformans" first appeared. He had described the mid- to late stages of patients with the chronic, debilitating, rare, and polyostotic forms of the disease. It is now known that the milder forms of the disease are quite common particularly in those of Anglo-Saxon ancestry. He believed the condition to be a chronic inflammation of unknown etiology because of its asymmetrical skeletal distribution, chronicity, and the gross appearance of the bones. With regard to the possible etiology of Paget's disease of bone, nothing worthy of note had been discovered until 1974 when viral-like inclusions were reported within the osteoclasts of all Paget's disease patients. In the ensuing decade, a great deal more circumstantial evidence from electron microscopic and immunologic studies supports the view that Paget's disease represents a slow virus infection. This article deals with the possible to probable viral etiology of Paget's disease with respect to its pathogenesis and its potential for eventual eradication. For many years Paget's disease was considered a disease almost exclusively confined to adulthood. Evidence now suggests that "familial chronic hyperphosphatasemia" represents the childhood form of Paget's disease.

Fifty-one cases of central, hyalin cartilage tumors of the long and flat bones were analyzed. Although Grade 2 and 3 chondrosarcomas could be diagnosed on the basis of cytologic features alone, low-grade chondrosarcoma could not be adequately differentiated from pure, benign enchondroma(s) by cytology alone. The tumors can be distinguished by a new histologic approach based on tissue patterns. The crucial enchondroma patterns consist of multiple nodules of hyalin cartilage separated by normal marrow in conjunction with partial to complete encompassing plates of lamellar bone that conform to the irregular shapes of the cartilage nodules. The chondrosarcomatous patterns consist of a single confluent mass of cartilage, which commonly permeates the marrow, "trapping" host lamellar bone on all sides, and which forms bands of fibrosis between the confluent peripheral cartilage lobules. Other less common patterns included cartilagenous infiltration of the Haversian systems or marrow fat and/or the development of a soft tissue mass. A central secondary chondrosarcoma is defined as one that shows the combination of both the enchondromatous and chondrosarcomatous patterns. All 18 of the pure enchondromas diagnosed by the methods proposed in this article behaved with strict benignity (i.e., without evidence of recurrence or metastasis with an average follow-up period of 7.2 years). The 33 primary and secondary chondrosarcomas diagnosed using the described patterns behaved with the predicted frequency of recurrence, metastasis, and patient demise.

Pigmented villonodular synovitis (PVNS) of the knee joint remains a difficult and elusive entity to define and characterize. This entity most often appears in the young adult knee with nonspecific clinical features, including a painful range of motion and perhaps a sensation of locking. Detection and diagnosis of this localized soft-tissue mass are difficult because plain roentgenograms may be totally within normal limits. The case of a 21-year-old woman illustrates the use of magnetic resonance imaging (MRI) as an effective technique to define and characterize PVNS. Advantages of MRI include high-resolution/high-contrast multiplanar sections that depict bone, marrow, ligaments and tendons, fat, menisci, and articular cartilage in one image. In addition, MRI is noninvasive and requires no ionized radiation. MRI is an excellent clinical tool for the evaluation of intraarticular tumors of the knee joint.

Three cases of simple bone cysts (S.B.C) in association with cementum-like bone production are reported. Analysis of our cases and the 2 previously reported in the literature as so-called cementomas has led us to conclude that the "cementoma" of long bone is not a distinct entity, but merely, a form of S.B.C. associated with a peculiar, poorly cellular form of bone which mimics tooth cementum by light microscopy only. Electron microscopic studies of this substance demonstrate collagen fibers and numerous matrix vesicles which form the initial sites of calcification. Matrix vesicles are a product of osteoblastic activity and are never found in the cementum of the tooth or oral cementum producing tumors. We also report the first ultramiscroscopic observations on the wall of the simple bone cyst and its lining. Two cell types constitute the lining, having features identical to those described for type A and type B synovial cells. Because of this new observation, we believe, the most reasonable explanation for the simple bone cyst is that it represents a congenital "rest" of synovial tissue displaced into the thin, cortical metaphyseal region of bones at the synovial-capsularbone reflection. Its benign nature and slow growth would explain its discovery in early childhood and the marked preponderance of its proximal humerofemoral location dependent upon the fact that these 2 bones have the largest area of capsular to metaphyseal bone reflection.

A histologically proven case of solitary bone cyst of a cervical vertebral body seems not to have been previously reported. Cysts of sufficient size to be a potential source of pathologic fracture should be excised and filled with autologous bone grafts.

A chondroblastoma of the proximal humerus in a 15-year-old boy was removed en bloc due to its very large size and locally destructive, aggressive character. This case is reported because of the rarity of chondroblastomas excised en bloc; specimens were examined in detail by correlated roentgenographic, gross inspection, histologic and electron-microscopic methods.

Several large pulmonary lesions were found in a 45-year-old woman after therapy for a typical tibial giant cell tumor. The pulmonary lesions were incidentally found during a routine chest examination four years after the original bone tumor had been found. Removal of the lung lesions showed ordinary giant cell tumor identical to the primary bone tumor, with no evidence of sarcomatous transformation. After an analysis of 12 other well-documented cases in the world literature, we postulate that the lung lesions in this case probably represent benign "metastases;" i.e., benign tumor implants compatable with a good long-term prognosis, rather than the usual lethal course associated with the vast majority of metastatic malignancies.

The progression of femoral head osteonecrosis (FHON) culminates in destruction of the hip joint, a devastating consequence for young people who are predominantly affected. Core decompression, as a means of ameliorating the disease, was evaluated in 45 hips in 33 patients with nontraumatic FHON. The mean clinical and roentgenographic follow-up period was three years (range, 1-7 years). None of the ten Ficat Stage I hips progressed, 11 of 26 Stage II hips progressed, and five of nine Stage III hips progressed to coxarthrosis. In those hips in which there was an association with steroid therapy, there was 50% progression when steroids were continued, compared with 22% progression when steroids had been discontinued. Core decompression is prescribed for Ficat Stage I and II. Patients on continuous post-operative treatment with steroids for associated conditions should be advised of the high risk of progression.