Extraskeletal myxoid chondrosarcoma.

The medical records and histologic material of 16 patients with extraskeletal myxoid chondrosarcoma were reviewed. The mean age of the patients was 52 years. Thirteen tumors arose in the lower extremity. Thirteen patients presented with primary, localized disease, whereas three presented with pulmonary metastases. Treatment of the primary site included wide excision or amputation in 13 patients and marginal or intralesional resections with radiation in three patients. The mean followup was 7.4 years. Five patients were continuously disease free (5- and 10-year event free survival 43% and 14%, respectively). Local recurrence developed in four, and metastases developed in six of 13 patients presenting with localized disease. Of six patients who received chemotherapy for systemic disease, four had disease progression and died, and two had a response to chemotherapy (one partial, one complete). The mean survival after onset of metastases was 45 months. Overall 5- and 10-year survival was 87% and 63%, respectively. The current series suggests that extraskeletal myxoid chondrosarcoma is an intermediate-grade neoplasm with a tendency toward recurrence and metastasis. Survival after relapse may be prolonged. More effective therapy for systemic disease is needed.

Sciatic nerve resection in the thigh: a functional evaluation.

Patients with a soft tissue malignancy involving the sciatic nerve who present with neurologic loss generally are advised to have an amputation. Twenty patients who underwent limb-sparing procedures with complete resection of the sciatic nerve as treatment for neurofibrosarcomas (12 patients), liposarcomas (four patients), malignant fibrous histiocytomas (two patients), recurrent desmoid tumor (one patient), and epithelioid hemangioendothelioma (one patient) were reviewed retrospectively. The mean age of these nine women and 11 men at the time of surgery was 51 years (range, 28-84 years). The right sciatic nerve was affected in 12 patients. These tumors were large and high grade. A mean of 22 cm of the nerve had to be resected (range, 8-42 cm). Ten patients received preoperative radiotherapy and 16 patients had intraoperative or postoperative radiotherapy. At a mean followup of 35 months (range, 7-97 months), 14 of the 20 patients were alive. Two patients had local recurrences develop (10%), whereas 12 patients had distant metastases. The function of the 10 patients as assessed by the Toronto Extremity Salvage Score averaged 74%. Most patients indicated that walking in the house is not difficult, but walking is compromised as soon as an effort is needed. Four patients walk without a cane, four needed one cane, and two needed two canes. The patients experienced stiffness, a sense of numbness, and premature fatigue. The use of analgesics was infrequent. Generally, patients rated themselves to be mildly to moderately disabled. From this small number of patients, it is shown that a tumor involving the sciatic nerve can be treated by limb-sparing surgery, including complete nerve resection, as an alternative to hip disarticulation or hindquarter amputation because the limb salvage option provides an acceptable functional outcome.

Synovial chondromatosis of the shoulder.

We describe a case of synovial chondromatosis involving the shoulder. Presenting symptoms, radiographic features, intraoperative findings, and treatment options are discussed.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and ploidy analysis of 23 cases.

Twenty-three cases of extraskeletal myxoid chondrosarcoma, evaluated at the Mayo Clinic between 1968 and 1996, were studied for clinicopathologic features, immunohistochemical profile, Ki-67 activity, and ploidy status to identify adverse prognostic factors. Females and males were equally affected, and the median age at diagnosis was 50 years. The tumors were located mainly in the lower extremities (83%), and the median tumor size was 9.5 cm. Sixteen tumors showed low cellularity (70%), and eight tumors had high mitotic activity (more than two per 10 high-power fields). The tumors were immunoreactive for vimentin (89%), synaptophysin (72%), epithelial membrane antigen (28%), and S-100 protein (17%). Nine tumors were diploid, three aneuploid, and one tetraploid. Mean Ki-67 activity was 11% (range, 1 to 45%). The 10-year overall survival rate was 78%. On univariate analysis, tumor size > or = 10 cm, high cellularity, presence of anaplasia or rhabdoid features, mitotic activity more than two per 10 high-power fields, Ki-67 > or = 10%, and Ki-67 "hot spot" > or = 25% were associated with decreased metastasis-free or overall survival. Ploidy status was not associated with any adverse outcome. The presence of any of these adverse prognostic factors can indicate the possibility of a more aggressive behavior in extraskeletal myxoid chondrosarcoma, and a closer follow-up is suggested.

Fibroma of tendon sheath involving the patellar tendon.

Fibroma of tendon sheath is a benign soft-tissue tumor that usually arises in association with tendons or ligamentous structures. We describe, what is, to the best of our knowledge, the first reported case of fibroma of tendon sheath involving the patellar tendon.

Vascularized free fibular transfer combined with autografting for the management of fracture nonunions associated with radiation therapy.

BACKGROUND: The purpose of this study was to evaluate the functional results, rates of union, and complications associated with vascularized free fibular transfer combined with autografting for the treatment of nonunions in previously irradiated bone. METHODS: Seventeen patients who had had eighteen vascularized free fibular transfers combined with autografting for the treatment of nonunion of a fracture in previously irradiated bone were included in this study. There were eleven female patients and six male patients. Eight patients had a bone neoplasm and nine, a soft-tissue neoplasm. The diagnosis was Ewing sarcoma in four patients; lymphoma, malignant fibrous histiocytoma, and rhabdomyosarcoma in two patients each; and cavernous hemangioma, metastatic breast carcinoma, reticulum-cell sarcoma, myxosarcoma, hemangiopericytoma, and fibrosarcoma in one patient each. The remaining patient had a soft-tissue tumor for which the diagnosis was not known. All patients received radiation therapy. The average dose was 5564 centigray. There were no recurrent tumors. The average interval between the radiation therapy and the original fracture was 111 months. The fracture was in the femur in thirteen patients, in the humerus in three, and in the tibia in one. All patients had operative or nonoperative treatment, or both, of the initial fracture, and two had iliac-crest bone-grafting after the initial open reduction and internal fixation procedure. The ages of the patients ranged from thirteen to eighty-two years at the time of the vascularized free fibular transfer. All fibular transfers were applied as onlay grafts because no nonunion was associated with a large segmental defect. Cancellous autogenous bone graft from the iliac crest was used as an additional graft at the proximal and distal junctions of the graft with the bone and at the fracture site in all patients. The average duration of follow-up after the vascularized free fibular transfer was fifty-seven months (range, twenty-eight to 112 months). RESULTS: Sixteen of the eighteen fracture sites united, after an average of 9.4 months (range, three to twenty-four months). Thirteen patients had an excellent result, one had a good result, two had a fair result, and one had a failure of treatment. Four patients had an infection, including one who continued to have a nonunion. The other three patients had union after treatment with antibiotics, debridement, and removal of the hardware. Another patient who had a recalcitrant nonunion eventually required an above-the-knee amputation. CONCLUSIONS: On the basis of this review, we suggest that microvascular fibular transfer combined with autografting is an appropriate treatment option for difficult nonunions associated with previously irradiated bone.

Identification of optimal strategies for increasing whole arm strength using Karush-Kuhn-Tucker multipliers.

OBJECTIVE: The purpose of this study was to develop a computer model for identifying muscles critical to improving functional upper extremity strength. DESIGN: A three-dimensional biomechanical model of the upper extremity was developed, and the predictions were compared to maximal arm strength data collected from healthy volunteers. BACKGROUND: Although several optimization-based mathematical models of the shoulder have been developed, none have utilized the mathematical properties of the Karush-Kuhn-Tucker multipliers to efficiently estimate the effect of strengthening individual muscles on functional strength of the whole arm. METHODS: A static three-dimensional biomechanical model of the glenohumeral, radio-humeral, ulno-humeral and wrist joints was developed for predicting maximal hand exertion forces. The model was formulated as a linear program. Constraints consisted of moment equilibrium conditions and limits on maximum and minimum allowable muscle forces. Predicted arm strengths were compared to maximal pull strength measurements made on 10 subjects (5 male; 5 female). The task involved pulling toward the mid-sagittal plane of the body with the arm flexed 45 degrees. The Karush-Kuhn-Tucker variables associated with the maximal limits on muscle force were computed to estimate the effect of altering the strength of individual muscles on functional arm strength. RESULTS: Maximum pull strengths were predicted well by the model. Karush-Kuhn-Tucker values ranged from 0 (for muscles not at their upper force limits) to 0.11 for the flexor carpi radialis and pectoralis major muscles. Karush-Kuhn-Tucker multipliers were found to be insensitive to the assumed specific tension of muscle. CONCLUSIONS: Upper extremity strength can be predicted from musculoskeletal geometry and physiology using linear programming. RELEVANCE: Karush-Kuhn-Tucker multipliers associated with the muscle force upper limits give insight into the effect of strengthening individual muscles on whole arm exertion strength. Such an analysis may provide insight into the development of optimal rehabilitation protocols.

Biomechanical analysis of prophylactic fixation for middle third humeral impending pathologic fractures.

For determination of the most biomechanically desirable construction for prophylactic fixation of impending central 1/3 humeral fractures, 24 matched pairs of fresh frozen skeletonized human cadaveric humeri were divided randomly into four groups. Group 1 compared intact humeri with matched humeri that had a 50% hemicylindrical cortical central 1/3 defect to show reproducible failure at the defect with significant reduction in strength. Groups 2 through 4 compared prophylactic fixation of the defect combined with cementation and dynamic compression plating, Rush rodding, or locked intramedullary nailing. Each specimen was tested in external rotation torsion to failure by fracture. In Group 1, test specimens with defects failed with significantly lower rotation to failure, peak torque, stiffness, and total energy absorbed to failure. In Groups 2 through 4, intramedullary nailing provided statistically significantly better total energy absorbed to failure and stiffness than did dynamic compression plating. The proximally and distally locked intramedullary nail seems to have biomechanical advantages in the prophylactic stabilization of an impending pathologic fracture of the central 1/3 of the humerus. These biomechanical findings must be considered in light of the clinical context when a means of fixation is selected.

Infection after rotator cuff repair.

Sixteen patients (15 men and 1 woman) were treated for infection complicating rotator cuff repair during the period 1975 through 1994. Eight of the 16 patients had their initial procedure performed elsewhere. The remaining 8 procedures were performed at our institution with the known incidence of this complication being 0.27%. In addition to intravenous antibiotic therapy, an average of 3.5 (range 2 to 8) operative procedures were required to eradicate the infections. Micro-organisms cultured were Propionibacter in 6, coagulase negative Staphylococcus in 4, Staphylococcus aureus in 4, Peptostreptococcus magnus in 1, and both Propionibacter and coagulase-negative Staphylococcus in 1. The deltoid was restored in all patients; the rotator cuff was reparable in 11. In the 12 shoulders with greater than 1 year of follow-up (average 51 months, range 14 to 165 months), active elevation averaged 110 degrees and external rotation 50 degrees. Four patients had no pain, 4 had minimal pain, and the remaining 4 had moderate pain. Satisfactory final results, which were determined by the patients' opinion or with the use of either the University of California, Los Angeles score or the modified Neer system, were obtained in 5 (42%) of the shoulders.

Biologic attachment of an allograft bone and tendon transplant to a titanium prosthesis.

An Achilles tendon allograft with its bony insertion was used to bridge a Titanium implant, containing an endoprosthetic tendon anchor, and the sheep biceps muscle. Twelve sheep were operated on unilaterally and followed up clinically and histologically for 2, 4 (n = 2), 8, and 12 months (n = 4). Full function of the front limb was regained after 8 to 12 weeks. There were no signs of mechanical loosening at all times. The morphologic changes at the bone block and implant fixation site were an initial revascularization of the allograft bone, which was observed at 2 months and enhanced at 4 months but occurred without any evidence of bone remodeling. This was changed in all specimens taken at 8 and 12 months where intensive new bone development, remodeling, and bone ingrowth in the titanium implant was found. Bone mass was shifted significantly to the tendon insertion half of the bone block because of a creeping substitution of the cancellous allograft bone and bone ingrowth to the implant. Overall bone mass slightly decreased with time but resorption of allograft bone outweighed new bone development only at lesser loaded areas. Transplantation of a bone and tendon allograft to an implant resulted in a revitalized, mechanically stable, and biologically anchored compound.

Repeat cDNA synthesis and RT-PCR with the same source of RNA.

A simple method has been developed that enables reextraction of RNA from an RNA-cDNA mixture. The reextracted RNA was converted to cDNA followed by polymerase chain reaction (PCR). Thus, cDNA synthesis (followed by PCR) was carried out two times on the same source of RNA. The method has been applied to 40 RNA samples of diverse tissue origin with a success rate of 100%. Thus, the method offers more versatile use of small but valuable RNA sources than currently possible.

High temperature cDNA synthesis by AMV reverse transcriptase improves the specificity of PCR.

The enzyme avian myeloblastosis virus reverse transcriptase (AMV-RT) is routinely used for cDNA synthesis, which is generally carried out at temperatures between 37 degrees C and 42 degrees C. We show that this enzyme can support cDNA synthesis, at temperatures as high as 70 degrees C. We have utilized this property of the AMV-RT to improve the specificity of polymerase chain reaction (PCR). Furthermore, this apparently thermophilic property of the enzyme, which is an important constituent of a mesophilic organism, raises intriguing questions regarding evolution of the enzyme structure.

Chondromyxoid fibroma of bone: a clinicopathologic review of 278 cases.

In a study of the clinical, radiographic, and pathological features of chondromyxoid fibroma, the tumor was slightly more common in men, usually in the second decade of life. Almost half of the tumors involved the long bones, although the ilium and the small bones were also common sites. Roentgenograms showed a sharply marginated, lobulated, lucent defect in the metaphysis. The tumor involved the medullary bone in an eccentric fashion, and the cortex was thinned and expanded. Periosteal reaction and soft tissue extension were uncommon. Mineralization was identified in 13% of the lesions. Histologically, the tumors were almost always arranged in lobules, which were prominent (macrolobular) or somewhat indistinct (microlobular). The tumor cells were spindle-shaped or stellate and arranged in a myxoid matrix. Calcification was seen in more than one third of the cases but was rarely prominent. Hyaline cartilage and chondroblastoma-like areas were not uncommon. Approximately 18% of tumors showed bizarre nuclei. Permeation of bony trabeculae was uncommon. Treatment was conservative surgical removal; approximately one fourth of the patients had recurrence.

Histologic and biochemical differences between osteolytic and nonosteolytic membranes around femoral components of an uncemented total hip arthroplasty.

The unique design characteristics of an uncemented femoral component were used to study differences in the periprosthetic membranes in the presence and absence of osteolysis. A component (Omniflex, Osteonics, Allendale, NJ) that has a large midportion of the stem that does not contact bone was studied. A membrane forms, even in the absence of bone resorption, in Gruen zones 3 and 5 of this component. Analysis of this membrane showed noninflammatory fibrous tissue, no or minimal particulate debris, and few macrophages. In contrast, analysis of membranes from osteolytic regions around the same prosthesis demonstrated typical inflammatory characteristics. Collagenase, gelatinase, and stromelysin expression was high in osteolytic membranes but was low in tissues from noninflammatory regions without osteolysis. The data suggest a sequence of events in periprosthetic membrane formation. A noninflammatory membrane initially forms between the bone and the prosthesis. This membrane is transformed into an inflammatory membrane by the influx of particulate debris. Matrix metalloproteinases are selectively expressed in regions of osteolysis, implicating these enzymes in periprosthetic bone loss and suggesting a possible level for pharmaceutical intervention to prevent or treat osteolysis. Formation of the noninflammatory membrane around the distal part of the prosthesis of this or similar designs in the absence of bone resorption implies that these tissue samples could serve as useful negative control tissues to identify factors present in osteolytic periprosthetic membranes.

Evidence for the upregulation of osteogenic protein-1 mRNA expression in musculoskeletal neoplasms.

Little is known about bone and cartilage tumors at the molecular level; thus, the identification of genes associated with these tumors may be useful as markers and therapeutic targets. To address this issue and to test the hypothesis that abnormal expression of one or more growth factors in the transforming growth factor-beta superfamily is associated with musculoskeletal neoplasia, degenerate primers based on the conserved sequences in these genes were made for screening tumor samples by reverse transcription-polymerase chain reaction. First, these primers were used to obtain a comparative profile between a low-grade chondrosarcoma and its dedifferentiated high-grade counterpart in the same patient. This experiment identified an amplified DNA product in the high-grade sample that was identical to osteogenic protein-1/bone morphogenetic protein-7. Osteogenic protein-1 mRNA expression was 17-fold greater in this high-grade sample than in the low-grade one. Osteogenic protein-1 was highly expressed (three of three) in human osteosarcoma cell lines but was not expressed (zero of four) in normal osteoblast samples. Screening for gene expression of osteogenic protein-1 in 57 osteosarcomas and chondrosarcomas indicated that 44% (range: 38-52%) of them were positive for osteogenic protein-1 mRNA. Screening of breast and prostate tumors revealed a similar association with osteogenic protein-1 mRNA expression.

Functional laboratory assessment after oncologic shoulder joint resections.

A laboratory evaluation was undertaken to assess the shoulder range of motion and distal strength after oncologic resection and reconstruction involving the shoulder joint and to compare these functional parameters based on potentially important variables. Inclusion in the study was limited to 32 patients with bone tumors of the proximal humerus or scapula treated surgically by resection of the shoulder joint including the proximal humerus from 1976 through 1992. Active shoulder range of motion and isometric elbow extension and forearm supination strength are significantly less after surgery in patients with greater amounts of bony resection and with resection of the deltoid. Patients who had a modified Tikhoff-Linberg resection were able to achieve 10 degrees to 15 degrees greater shoulder motion in each direction than were patients who had the classic procedure including complete scapulectomy. However, elbow flexion and extension strength and forearm pronation strength were greater for the patients with the classic resection. Osteoarticular allografts as a reconstructive alternative provide as a group the best shoulder motion and overall distal upper extremity strength, but these reconstructions were performed only when the rotator cuff muscles and deltoid were able to be reconstructed. Diminishing elbow strength was seen with longer followup in the patients with osteoarticular reconstructions, corresponding temporally to subchondral collapse observed on radiographs. Range of shoulder motion except rotation was just as good for allograft vascularized fibular arthrodeses as for the osteoarticular allografts, but strength was significantly less with the arthrodeses.

Giant-cell tumour of bone metastasising to the lungs. A long-term follow-up.

We reviewed 23 patients with a giant-cell tumour (GCT) of bone and histologically-proven lung metastases at a mean of 11.9 years (3 to 24.5) after the original diagnosis. The mean age of the patients at diagnosis was 27.3 years (9 to 61); the male to female ratio was 0.9:1. The most common primary site was the distal radius. The mean interval between the onset of the tumour and the detection of lung metastases was 4.1 years (0 to 24). There had been local recurrence in 19 (83%) either before or at the time of diagnosis of lung metastasis. Surgical resection alone was the preferred treatment for lung metastases in 70% and resulted in 18 patients (76%) being free from disease when last reviewed. One patient had the spontaneous regression of lung metastases and was free from recurrence 16 years later. Sixteen patients (69.7%) have survived and four (17.4%) have died from progression of the tumour. Three other deaths were not related to the tumour. Local recurrence and a primary lesion at the distal radius seem to be associated with an increased risk of lung metastases. Repeated surgical resection of lung metastases gave a high rate of survival.

Distal upper extremity function following proximal humeral resection and reconstruction for tumors: contralateral comparison.

BACKGROUND: Most functional analyses after limb salvage operations about the shoulder have focused on proximal function with the assumption that distal function is largely unaffected. This analysis examines distal function objectively. METHODS: Objective laboratory data regarding distal upper extremity strength after reconstructive procedures for tumors near the shoulder joint was collected over a 16-year period. Thirty-two patients were able to participate fully in the data collection at an average most recent follow-up duration of > 3.5 years. RESULTS: Statistically significant reductions on the involved side compared with the uninvolved side in grip, forearm pronation, forearm supination, elbow flexion, and elbow extension strength were documented (p < 0.05). The magnitude of reduction in strength diminishes distally, with the greatest effect in this group of patients being observed in elbow extension, followed by elbow flexion, forearm supination, and forearm pronation. Grip strength consistently showed the least amount of strength reduction compared with the uninvolved side, even within resection and reconstruction groups. Subjective patient rating of dexterity was no less than 3 of 5. Ninety percent of patients rated their dexterity 4 of 5 (52%) or 5 of 5 (38%). CONCLUSIONS: Despite the insistence of "normal" function in the distal upper extremity after limb salvage procedures, complete normality is not maintained. However, the degree of maintenance of distal function appears to be high, especially for grip strength and forearm pronation strength, and patient satisfaction is acceptable.

Unusual manifestations of proximal tibiofibular joint synovial cysts.

Synovial cysts emanating from the proximal tibiofibular articulation are commonly symptomatic and may progress to compromise peroneal nerve function. They may cause diagnostic confusion when they present as intraosseous masses or as soft tissue masses causing extrinsic bony erosion. Twelve cases treated surgically are reviewed. Electromyography and nerve conduction studies were valuable in localizing the lesions to the knee when no mass was palpable. Of the six cases involving the peroneal nerve, three required loupe or microscopic dissection of the cyst from within the epineurium. Two other cases had bony changes. Magnetic resonance imaging, though not diagnostic, is valuable in planning the dissection.