Intraosseous epidermoid cyst in a metacarpal mimicking malignancy.
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Bone Neoplasms↗
Biomedical subjects
M G Rock
Publications and source records attributed to M G Rock.
A differential scanning calorimetry study of retrieved orthopedic implants made of ultrahigh molecular weight polyethylene.
Differential scanning calorimetry (DSC) was used to examine thermal and thermooxidative properties of ultrahigh molecular weight polyethylene (UHMW-PE) of five acetabular components of failed orthopedic implants retrieved at revision of total hip arthoplasty. The results were compared with controls (unimplanted acetabular cups, a 20-year-old slab of UHMW-PE, and raw material). Profiles of exothermic peaks indicated increased levels of oxidation in all retrieved cups. In three retrieved cups, DSC revealed an additional peak of endotherm that was not seen in control samples. The additional endotherm peaks were not artifacts due to oxidation during scanning, heat buildup during cutting of the samples, or the sterilization method after retrieval. The additional peak was associated with the bulk of the polymer that was extracted with hexane. It varied in relative area, depending on its original location of the sample in a cup, implicating local variability in the extent of changes in material property. The distribution of the changes suggests that, during implantation, tissue exposure and friction affected the level of oxidation and degree of crystallinity in the UHMW-PE to a greater degree than did loading alone. Overall results showed that DSC may be a useful tool in evaluating changes in the properties of UHMW-PE orthopedic components in vivo.
Acetabulum↗
Fixation of femoral allograft/prosthesis composites after 25%, 50% and 75% resection.
The relative linear and angular displacements of proximal femoral reconstructions were compared within six different replacement techniques during ex vivo axial compression, mediolateral bending, and axial torsion in dogs. Each femur was osteotomized at 25%, 50%, or 75% of its length and the proximal portion subsequently replaced using one of six techniques. The reconstruction techniques included various combinations of proximal and distal fixation methods (graft fixation/distal fixation): (1) an allograft/prosthesis composite (APC) press-fit proximally and cemented distally (press-fit/cement); (2) APC cemented proximally and distally (cement/cement); (3) APC cemented proximally and the host bone/graft interface double plated (cement/plates); (4) APC cemented proximally and secured distally with bicortical screws (cement/screws); (5) APC secured proximally and distally with bicortical screws (screws/screws); (6) Segmental proximal femoral replacement cemented into the distal femur without an allograft (no graft/cement). For axial compression and mediolateral bending, the combined resection lengths revealed no differences in linear and angular displacements, respectively, between reconstruction methods. During axial torsion, the cement/cement technique allowed larger angular displacements than all but the press-fit/cement technique which had larger displacements than the cement/screws, screws/screws, and no graft/cement groups (p < 0.0001). Overall, the measured implant stability was solid and consistent as evidenced by small amounts of relative displacement and small error values.
Animals↗
Inflammatory pseudotumor of nerve.
Two cases of inflammatory pseudotumor are described. The first patient, a 35-year-old white man, developed a progressive sensorimotor deficit in the right leg associated with a fusiform sciatic nerve mass in the posterior thigh. The lesion, compressive in nature and situated entirely within the epineurium, was totally resected. Histology revealed lymphocytic and plasmacellular inflammation as well as extensive fibrosis and collagen deposition. The patchy infiltrate consisted equally of CD2, CD3, CD5, and CD7 positive T-lymphocytes as well as CD20-and CD22-positive B-lymphocytes expressing both kappa and lambda immunoglobulin light chains. A selective biopsy of the encompassed and compressed nerve fascicles demonstrated both myelin loss and axonal injury. The second case was that of an 18-year-old woman with focal enlargement of a radial nerve by an epineurial infiltrate of multinucleate histiocytes and T as well as occasional B lymphocytes. No etiology was apparent in either case. The differential diagnosis includes non-neoplastic processes (amyloidoma and tuberculoid leprosy) as well as tumors (benign and malignant peripheral nerve sheath tumors, lymphoma). Although rare, inflammatory pseudotumors must be included in the differential diagnosis of tumor-like lesions of peripheral nerve.
Adolescent↗
Low grade central osteogenic sarcoma. A long-term followup of 20 patients.
Osteogenic sarcoma is a heterogeneous family of tumors that has a variable biologic behavior. Low grade central osteogenic sarcoma is an uncommon form that is characterized by a long premorbid history and is compatible with prolonged survival after treatment. Twenty cases of low grade central osteosarcoma with long-term followup (16 [2.5-48] years) were studied retrospectively. The age distribution was broad (range, 15-83 years). All tumors arose in the lower limb. The primary symptom was pain; mean duration was 44 months (range, 1-180 months). A diagnosis of low grade central osteosarcoma was made primarily for 11 patients. For 9 others, fibrous dysplasia (3), nonossifying fibroma (2), fibroma (1), chondromyxoid fibroma (1), chondrosarcoma (1), and simple bone cyst (1) were diagnosed initially. Intralesional surgery was associated with recurrence in every case. Radical margins were not associated with local recurrence. Four recurrences were higher grade and 1 was dedifferentiated. Three of 4 patients with metastases died of their disease. Five- and 10-year survival was 90% and 85%, respectively. Histology and radiology are complementary for confirming the diagnosis. Low grade central osteosarcoma seems to be controllable by surgery alone if at least wide margins are used.
Adolescent↗
Intercalary spacers in the treatment of segmentally destructive diaphyseal humeral lesions in disseminated malignancies.
During a 10-year period, 17 patients with segmentally destructive bone lesions of the humeral diaphysis in disseminated malignancies resulting in impending fracture (8 patients), pathologic fracture (6 patients), or failure of attempted internal fixation techniques (3 patients) were treated with resection of the involved diaphyseal segment and reconstruction with a cemented modular intercalary humeral spacer. Fourteen patients had metastatic cancer, 2 had multiple myeloma, and 1 had lymphoma. Breast and renal carcinoma were the most common pathologic diagnoses. The involved site was within the middle 1/3 in 8 patients, in the proximal-middle junction in 5, in the middle-distal junction in 2, and within the proximal and distal 1/3 in 1 patient each. Early pain relief was successful in 88% of patients. Early in the postoperative hospital course, patients generally were able to use the ipsilateral hand to assist feeding. Radiographic analysis revealed that the limited selection of stem lengths led to 76% of the distal stems and 47% of the proximal stems being shorter than the ideal length. The complication rate independent of disease progression was 29%. The most common complication was temporary radial nerve injury (3 patients). There were 3 implant failures, most commonly due to disengagement of the male-female junction. Two periprosthetic fractures occurred, 1 proximally (due to tumor progression) and 1 distally. Suggestions are given for modification of the implants to improve the major problems of limited versatility in intramedullary stem length and inadequate mating at the junction.
Adult↗
Comparison of soft tissue Ewing's sarcoma and peripheral neuroectodermal tumor.
Thirty-four cases with either extraskeletal Ewing's sarcoma (21 patients) or malignant peripheral neuroectodermal tumor of the soft tissues (13 patients) were reviewed retrospectively. The patients were treated between 1964 and 1991. Followup periods averaged 7.2 years for patients with peripheral neuroectodermal tumors and 10.4 years for patients with Ewing's sarcoma (minimal followup of 2 years). There were no significant differences in patient's age, gender, tumor location, and stages on presentation between patients with Ewing's sarcoma and those with malignant peripheral neuroectodermal tumor of the soft tissue. All but 2 patients underwent surgery for tumor resection. Adjunctive therapy (radiation or chemotherapy or both) was administered in 95% of the patients with Ewing's sarcoma and in 85% of the patients with peripheral neuroectodermal tumors. The 5-year overall survival was 50% for Ewing's sarcoma and 44% for peripheral neuroectodermal tumor. The 5-year disease free survival was 33% for both types of tumors. Survival rates were higher for Stage III compared with Stage IV disease for both types of tumors. There was a tendency for better outcome after complete surgical tumor resection. Survivors tended to be of a younger age at the time of tumor diagnosis. The results suggest that from a clinical perspective, these 2 tumors are quite similar.
Adolescent↗
Megaprostheses after resection of distal femoral tumors. A rotating hinge design in 30 patients followed for 2-7 years.
Between 1981-1993, we inserted 32 Kinematic Rotating-Hinge Knee tumor prostheses in 30 patients, of which 2 concerned revisions of the same type of prosthesis. The diagnoses were 21 osteosarcomas, 2 chondrosarcomas, 2 Ewing's sarcomas, 2 metastatic breast carcinomas, 1 multiple myeloma, 1 giant cell tumor and 1 Gorham's disease. The median age was 25 (12-60) years and the median follow-up for survivors was 3.5 (2-6.6) years. There were 7 metastases and 1 local recurrence. 20 knees had excellent (MSTS) scores for motion (median flexion 120 degrees), 8 had good (84 degrees) and 4 had fair (45 degrees). The overall function was excellent in 6 cases, good in 14, fair in 9 and poor in 3. The radiographic assessment (ISOLS) gave "excellent" or "good" scores in 27 knees for bone remodelling, 31 for the interface, 28 for the anchorage, 31 for the implant body and 30 for the articulation. Extracortical bone bridging greater than 25% was observed in 18 of 27 prostheses.
Adolescent↗
Comparison of healing of allograft/endoprosthetic composites with three types of gluteus medius attachment.
This study compared three methods of gluteus medius tendon attachment to an allograft/endoprosthetic composite of the proximal 25% of the femur in a canine model. The three methods were bone to bone, tendon to bone, and tendon to tendon attachment. In an in vivo study, 24 dogs were assigned to three groups of eight dogs each, and serial radiography and weight-bearing analyses were performed throughout the study. The dogs were killed at 6 months, and the specimens were tested in tension to failure and were analyzed histologically. In an in vitro study, each repair was done on six limbs, with a contralateral limb serving as a control for each. In these specimens, the bone to bone attachments were significantly stronger (99.1% of the controls) than the tendon to bone attachments (71.8% of the controls) and the tendon to tendon attachments (40.0% of the controls); there were no differences in tensile stiffness among the three types of attachment. By 6 months, the tensile strength of the tendon to tendon attachments increased significantly and that of the tendon to bone attachments decreased significantly. There were no significant differences in tensile strength among the three types of attachment. The tensile stiffness of the bone to bone attachments (91.0% of the controls) was significantly greater than that of the tendon to bone attachments (40.8% of the controls) but not significantly different from that of the tendon to tendon attachments (63.2% of the controls). The bone to bone attachment was associated with increased bone resorption, bone remodeling, and bone porosity, accompanied by thinner allograft cortices, when compared with the other types of attachment. In dogs with a bone to bone attachment, weight-bearing increased more slowly than in dogs with either of the other two attachments. These changes associated with the bone to bone attachment may merely be secondary to healing of the bone to bone attachment to the greater trochanter; therefore, they may only be temporary phenomena or they may be the portents for long-term complications. Longer term studies of at least 1-2 years must be performed before these questions can be answered.
Animals↗
Comparison of allograft/endoprosthetic composites with a step-cut or transverse osteotomy configuration.
This study was designed to compare the biomechanical and functional characteristics of allograft/endoprosthetic composites of the proximal 25% of the femur repaired with either a transverse or a step-cut osteotomy, using a canine model (10 dogs, five with each type of osteotomy). Serial radiography and weight-bearing studies were performed monthly, and mechanical testing was done 6 months after surgery. The femora were tested in torsion and compared with the contralateral control (insertion of a femoral component but no osteotomy). At 6 months, the composites with a step-cut osteotomy had 36% greater structural stiffness than the composites with a transverse osteotomy (p < 0.005) and 121% greater maximum torque at failure than the controls (p < 0.005), without greater structural stiffness. Evaluation of peak vertical ground reaction forces revealed significantly greater weight-bearing on the experimental limb in dogs with a transverse osteotomy. The results of this relatively short-term study were mixed. Despite the increased structural stiffness of the allograft/endoprosthetic composite with a step-cut osteotomy, the dogs with this type of reconstruction had decreased weight-bearing throughout the course of the study. The step-cut osteotomy may augment the stability of the allograft/endoprosthetic composite, allowing faster healing (as demonstrated by the results of mechanical testing), but in some way, not understood, may cause pain in the reconstructed limb. Longer term studies are needed to answer these questions and to determine whether alteration of the traditional transverse osteotomy has any advantage.
Animals↗
Survival after pulmonary metastasectomy in soft tissue sarcoma. Prognostic factors in 214 patients.
This retrospective study examines prognostic factors for post-metastasectomy survival in soft tissue sarcoma patients. Between 1976 and 1992, 274 consecutive patients (median age 49 [7-96] years) with pulmonary metastatic soft tissue sarcoma of the extremity or trunk wall (31 at presentation) were managed at the Mayo Clinic. 214 underwent pulmonary metastasectomy and 163 of these also received adjuvant chemotherapy. There were 195 local excisions, 14 lobectomies, and 5 pneumonectomies. 90 patients had solitary metastases, 184 patients had 2 or more metastases. 31% of patients had MFH tumors and 88% of all tumors were high grade. Median follow-up for survivors was 8 (2-21) years. 5-year overall survival after metastasectomy was approximately 40% (cf. 20% for non-metastasectomy). Age > 50, MFH tumors, > or = 2 metastases, metastasis size > 2 cm, metastasis-free period < or = 18 months, and the use of adjuvant chemotherapy were univariately unfavorable factors. Size of metastasis > 2 cm, number of metastases > or = 2, and metastasis-free interval < or = 18 months were independently unfavorable for survival. In a prognostic system, patients with 0 risk factors had a 60% 5-year survival, those with 1, 2, or 3 of these factors had 30%, 20% and 0% survival, respectively.
Adolescent↗
Ewing's tumor of the pelvis.
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Antineoplastic Combined Chemotherapy Protocols↗
Injuries in youth ice hockey: a pilot surveillance strategy.
OBJECTIVE: To determine the incidence and type of injuries in youth hockey players during practice and games as well as to test the applicability of the current methods to a national surveillance study of youth hockey injuries. DESIGN: During the 1993 to 1994 season, we undertook a prospective observational analysis of youth hockey players on four competitive teams at three levels of participation: Squirt, Peewee, and Bantam. MATERIAL AND METHODS: In a study group of 66 youth hockey players, types and anatomic sites of injury, mechanisms of injury, player position affected, and occurrence of injuries during practice or games were determined and analyzed statistically. An injury was strictly defined, standardized reporting strategies were used, and a single physician examined all injured athletes and made the diagnoses. RESULTS: A total of 14 injuries occurred during the season. The on-ice injury rate (per 1,000 player-hours) was 1.0 at the Squirt level (ages 9 and 10 years), 1.8 at the Peewee level (ages 11 and 12 years), and 4.3 at the Bantam level (ages 13 and 14 years). No game injuries and only one mild practice injury occurred in Squirt players (N = 16), and only two mild injuries occurred during practice sessions for Peewees (N = 17). No differences were noted between practice injury rates at the various levels; all recorded game injuries occurred only in Bantam players (N = 33). The most common types of injuries were contusions, fractures, strains, and sprains. The arm and shoulder were most frequently injured. CONCLUSION: Further research is necessary to determine whether injuries in youth ice hockey can be reduced by changes in playing rules, enforcement of existing rules, improvements in protective equipment, alteration in coaching techniques, and institution of educational programs.
Adolescent↗
Subcutaneous involvement after a metacarpal chondrosarcoma. Case report and review of literature.
The relatively high probability of local recurrence after excision of chondrosarcomas has been attributed to the avascularity of the cartilage tumor matrix, making the neoplastic cells less dependent on an extrinsic blood supply. This report is of a case of subcutaneous involvement by chondrosarcoma from a metacarpal to a site on the ipsilateral forearm several centimeters remote from the resection incision in the absence of local recurrence or pulmonary metastases. The pertinent literature regarding cutaneous involvement, local recurrence, and transplantation of cartilage neoplasms is reviewed.
Aged↗
Mechanical evaluation of six types of reconstruction following 25, 50, and 75% resection of the proximal femur.
The structural stiffness and the stiffness of the osteotomy site after six types of reconstruction of the proximal femur were compared by testing in axial compression, mediolateral bending, and axial torsion in a canine model. An osteotomy was carried out for 25, 50, or 75% of the length of each femur, and the proximal portion was replaced by one of five allograft/endoprosthetic composites or a segmental replacement. The reconstructions included (a) a composite press-fit proximally and cemented distally, (b) a composite cemented proximally and distally, (c) a composite cemented proximally and fixed with two plates at the allograft-host bone interface, (d) a composite cemented proximally and secured distally with bicortical screws, (e) a composite secured proximally and distally with bicortical screws, and (f) a segmental prosthesis cemented into the distal femur. The results showed that the segmental reconstruction and the reconstruction with double-plate fixation and a cemented endoprosthesis were structurally stiffer and had greater stiffness of the osteotomy site than the other reconstructions. In comparison, reconstructions that involved cement alone or cement and press-fit techniques generally were more compliant than the others, both structurally and at the osteotomy site.
Animals↗
Well-differentiated liposarcoma. The Mayo Clinic experience with 58 cases.
The clinicopathologic results from 58 patients with well-differentiated liposarcomas are reported. Thirty-two tumors involved the extremities, 20 the retroperitoneum, 4 the scrotum, 1 the abdominal wall, and 1 the cheek. Most tumors were large (mean, 22.6 cm). There were 31 (53%) lipoma-like, 23 (40%) sclerosing, and 4 (7%) primary dedifferentiated tumors. Six tumors underwent dedifferentiation after recurrence. The average follow-up period was 9.3 years. Thirty-seven patients (64%) were alive with no evidence of disease; 7 (12%) were alive with disease; 8 (14%) died of disease; and 6 (10%) died of other causes. Dedifferentiation did not indicate imminent death; 5 of the 10 patients were alive with no evidence of disease. Three dedifferentiated tumors subsequently recurred as pure well-differentiated liposarcomas. Patients with extremity tumors had a significantly better prognosis than those with retroperitoneal or scrotal tumors (P = .006). Extremity tumors treated by wide local excision recurred in only 11% of cases, whereas 60% of those treated by marginal or simple excision recurred.
Adult↗
Massive subacromial bursitis with rice bodies. Report of three cases, one of which was bilateral.
Multiple cartilaginous-like bodies (rice bodies) in joints or bursae may be the presenting sign of a more extensive underlying rheumatic condition. Three patients with massive subacromial bursae with rice bodies are described, one of whom had bilateral occurrence. In all patients, excision of the bursa and rice bodies relieved the symptoms. The underlying rheumatic condition continued its course, generally sparing the involved shoulder joint. Review of these cases reinforces the need to provide a thorough examination for systemic rheumatologic disease in patients diagnosed with this lesion.
Acromioclavicular Joint↗
Nonepiphyseal giant cell tumor of the long bones. Clinical, radiologic, and pathologic study.
BACKGROUND: Giant cell tumors (GCT) usually involve the epiphyses of long bones and only rarely involve the metaphysis or diaphysis without epiphyseal extension. METHODS: This report presents the clinical and pathologic features of 14 patients with metaphyseal and diaphyseal GCT. Of these tumors, 10 were metaphyseal; 2, metadiaphyseal; and 2, diaphyseal. RESULTS: The sites of involvement included the proximal tibia in six patients, distal radius in three, proximal fibula in one, distal fibula in one, distal ulna in one, proximal humerus in one, and distal femur in one. Radiographically, the tumors were lucent, and the majority were sharply marginated without sclerosis. By contrast with conventional epiphyseal GCT, which generally appear in the mature skeleton, a large proportion (50%) of the GCT in this series were in patients who had open epiphyseal growth plates. Despite the unusual clinical presentation, the behavior of metaphyseal and diaphyseal GCT was similar to that of the typical epiphyseal GCT. There was a 43% recurrence rate after curettage in this series. CONCLUSIONS: It is important to distinguish this subset of GCT from other giant cell-rich lesions more common in these sites, including aneurysmal bone cyst, osteosarcoma, and nonossifying fibroma.
Adolescent↗