Partnership in Cancer Research (PCAR) Program Increases Medical Student Knowledge and Confidence to Perform Cancer Research

Arkansas has a high cancer burden, and a pressing need exists for more medical students to pursue oncology as a career. The Partnership in Cancer Research (PCAR) program provides a summer research experience at the University of Arkansas for Medical Sciences for 12 medical students who have completed their first year of medical training. A majority of participants spend time pursuing cancer research in basic science, clinical, or community-based research. Students report on their research progress in an interactive "Live from the Lab!" series and assemble a final poster presentation describing their findings. Other activities include participation in a moderated, cancer-patient support group online, lecture series on cancer topics, medical simulations, palliative care clinic visit, "Death Over Dinner" event, and an entrepreneurship competition. Students completed surveys over PCAR's first 2 years in operation to evaluate all aspects of the program. Surveys reveal that students enthusiastically embraced the program in its entirety. This was especially true of the medical simulations which received the highest evaluations. Most significantly, surveys revealed that the program increased cancer knowledge and participant confidence to perform cancer research.

Safe Positioning for Sexual Intercourse After Proximal Femoral Replacement

Hip arthroplasty is a common procedure used for the treatment of fractures and degenerative processes affecting the hip. Proximal femoral replacement is an uncommon type of hip arthroplasty used for reconstruction after extensive bone loss. Proximal femoral replacement is used most commonly after the resection of the proximal femur for malignancies and for extensive bone loss encountered in revision hip arthroplasty and occasionally for extensive bone loss after fractures. The authors present a case of a female patient who sustained a prosthetic dislocation of her proximal femoral replacement during sexual intercourse. Standard hip arthroplasty itself can pose a risk factor for dislocation associated with certain sexual positions. Proximal femoral replacement surgery likely carries an increased risk for dislocation, given the magnitude of soft tissue loss at the time of resection. The authors believe that routine perioperative conversations for sexually active patients with proximal femur replacements should include this potential risk and discuss appropriate positioning to prevent a potential dislocation. [Orthopedics. 2018; 41(2):e292-e294.].

Nutlin-3 treatment spares cisplatin-induced inhibition of bone healing while maintaining osteosarcoma toxicity

The majority of Osteosarcoma (OS) patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. These protocols include distraction osteogenesis (DO), which is characterized by direct new bone formation. Cisplatin (CDP) is extensively used for OS chemotherapy and recent studies, using a mouse DO model, have demonstrated that CDP has profound negative effects on bone repair. Recent oncological therapeutic strategies are based on the use of standard cytotoxic drugs plus an assortment of biologic agents. Here we demonstrate that the previously reported CDP-associated inhibition of bone repair can be modulated by the administration of a small molecule p53 inducer (nutlin-3). The effects of nutlin-3 on CDP osteotoxicity were studied using both pre- and post-operative treatment models. In both cases the addition of nutlin-3, bracketing CDP exposure, demonstrated robust and significant bone sparing activity (p < 0.01-0.001). In addition the combination of nutlin-3 and CDP induced equivalent OS tumor killing in a xenograft model. Collectively, these results demonstrate that the induction of p53 peri-operatively protects bone healing from the toxic effects of CDP, while maintaining OS toxicity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1716-1724, 2016.

Comparative evaluation of local control strategies in localized Ewing sarcoma of bone: a report from the Children's Oncology Group

BACKGROUND

Patients with Ewing sarcoma require local primary tumor control with surgery, radiation, or both. The optimal choice of local control for overall and local disease control remains unclear.

METHODS

Patients with localized Ewing sarcoma of bone who were treated on 3 consecutive protocols with standard-dose, 5-drug chemotherapy every 3 weeks were included (n=465). Propensity scores were used to control for differences between local control groups by constructing multivariate models to assess the impact of local control type on clinical endpoints (event-free survival [EFS], overall survival, local failure, and distant failure) independent of differences in their propensity to receive each local control type.

RESULTS

Patients who underwent surgery were younger (P=.02) and had more appendicular tumors (P<.001). Compared with surgery, radiation had higher unadjusted risks of any event (hazard ratio [HR], 1.70; 95% confidence interval [CI], 1.18-2.44), death (HR, 1.84; 95% CI, 1.18-2.85), and local failure (HR, 2.57; 95% CI, 1.37-4.83). On multivariate analysis, compared with surgery, radiation had a higher risk of local failure (HR, 2.41; 95% CI, 1.24-4.68), although there were no significant differences in EFS (HR, 1.42; 95% CI, 0.94-2.14), overall survival (HR, 1.37; 95% CI, 0.83-2.26), or distant failure (HR, 1.13; 95% CI, 0.70-1.84) between local control groups.

CONCLUSIONS

In this large group of similarly treated patients, choice of the mode of local control was not related significantly to EFS, overall survival, or distant failure, although the risk of local failure was greater for radiation compared with surgery. These data support surgical resection when appropriate, whereas radiotherapy remains a reasonable alternative in selected patients.

Circulating interleukin-8 levels explain breast cancer osteolysis in mice and humans

Skeletal metastases of breast cancer and subsequent osteolysis connote a dramatic change in the prognosis for the patient and significantly increase the morbidity associated with disease. The cytokine interleukin 8 (IL-8/CXCL8) is able to directly stimulate osteoclastogenesis and bone resorption in mouse models of breast cancer bone metastasis. In this study, we determined whether circulating levels of IL-8 were associated with increased bone resorption and breast cancer bone metastasis in patients and investigated IL-8 action in vitro and in vivo in mice. Using breast cancer patient plasma (36 patients), we identified significantly elevated IL-8 levels in bone metastasis patients compared with patients lacking bone metastasis (p<0.05), as well as a correlation between plasma IL-8 and increased bone resorption (p<0.05), as measured by NTx levels. In a total of 22 ER+ and 15 ER- primary invasive ductal carcinomas, all cases examined stained positive for IL-8 expression. In vitro, human MDA-MB-231 and MDA-MET breast cancer cell lines secrete two distinct IL-8 isoforms, both of which were found to stimulate osteoclastogenesis. However, the more osteolytic MDA-MET-derived full length IL-8(1-77) had significantly higher potency than the non-osteolytic MDA-MB-231-derived IL-8(6-77), via the CXCR1 receptor. MDA-MET breast cancer cells were injected into the tibia of nude mice and 7days later treated daily with a neutralizing IL-8 monoclonal antibody. All tumor-injected mice receiving no antibody developed large osteolytic bone tumors, whereas 83% of the IL-8 antibody-treated mice had no evidence of tumor at the end of 28days and had significantly increased survival. The pro-osteoclastogenic activity of IL-8 in vivo was confirmed when transgenic mice expressing human IL-8 were examined and found to have a profound osteopenic phenotype, with elevated bone resorption and inherently low bone mass. Collectively, these data suggest that IL-8 plays an important role in breast cancer osteolysis and that anti-IL-8 therapy may be useful in the treatment of the skeletal related events associated with breast cancer.

Cisplatin inhibits bone healing during distraction osteogenesis

Osteosarcoma (OS) is the most common malignant bone tumor affecting children and adolescents. Many patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. Surgical reconstructions after tumor resection include structural allografts, non-cemented endoprostheses, and distraction osteogenesis (DO), which require direct bone formation. Although cisplatin (CDP) is extensively used for OS chemotherapy, the effects on bone regeneration are not well studied. The effects of CDP on direct bone formation in DO were compared using two dosing regimens and both C57BL/6 (B6) and tumor necrosis factor receptor 1 knockout (TNFR1KO) mice, as CDP toxicity is associated with elevated TNF levels. Detailed evaluation of the five-dose CDP regimen (2 mg/kg/day), demonstrated significant decreases in new bone formation in the DO gaps of CDP treated versus vehicle treated mice (p < 0.001). Further, no significant inhibitory effects from the five-dose CDP regimen were observed in TNFR1KO mice. The two-dose regimen significantly inhibited new bone formation in B6 mice. These results demonstrate that CDP has profound short term negative effects on the process of bone repair in DO. These data provide the mechanistic basis for modeling peri-operative chemotherapy doses and schedules and may provide new opportunities to identify molecules that spare normal cells from the inhibitory effects of CDP.

Evaluation of local control strategies in patients with localized Ewing sarcoma of bone: A report from the Children’s Oncology Group

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Background: Patients (pts) with Ewing sarcoma (EWS) require local control, either with surgery alone (S), radiation alone (R), or a combination of surgery + radiation (S+R). Optimal choice of local control for disease control remains unclear. Our primary aim was to determine the mode of local control associated with the highest event-free survival (EFS). Methods: Pts with localized EWS of bone treated on INT0091, INT0154, or AEWS0031 phase III trials were included if they had complete local control data, did not have cranial tumors, received local control starting 2-6 months after enrollment, and were randomized to receive standard dose 5-drug chemotherapy every 3 weeks. We used propensity scores to control for differences in age, tumor site, and year of diagnosis between local control groups. We constructed Cox models controlling for local control propensity scores to assess the impact of local control type on EFS and overall survival (OS) from the start of local control. Results: 465 pts were included. Pts selected for S were treated more recently (p < 0.001), more likely to have appendicular tumors (p < 0.001), and younger (p = 0.02). Pts treated with R, compared to S, had higher unadjusted risk of any event (HR 1.70; 95% CI 1.18 - 2.44; p = 0.004) or death (HR 1.84; 95% CI 1.18 – 2.85; p = 0.006). Pts treated with S+R, compared to S, had higher unadjusted risk of death (HR 1.75; 95% CI 1.10 – 2.76; p = 0.02). After adjusting for propensity scores, there was a trend of higher risk of any event for pts treated with R (HR 1.42; 95% CI 0.94 – 2.14; p = 0.10) compared to S, though this was not statistically significant. No other differences in adjusted risk of event or death between local control groups were statistically significant. We confirmed these results with standard Cox models using age, tumor site, and year of diagnosis as covariates. Conclusions: In this large group of uniformly treated pts, investigator choice of local control approach was not significantly related to EFS. These data support current practice of surgical resection when feasible, while validating radiotherapy as a reasonable alternative in selected pts.

Bone metastasis: mechanisms and therapeutic opportunities

The skeleton is one of the most common sites for metastatic cancer, and tumors arising from the breast or prostate possess an increased propensity to spread to this site. The growth of disseminated tumor cells in the skeleton requires tumor cells to inhabit the bone marrow, from which they stimulate local bone cell activity. Crosstalk between tumor cells and resident bone and bone marrow cells disrupts normal bone homeostasis, which leads to tumor growth in bone. The metastatic tumor cells have the ability to elicit responses that stimulate bone resorption, bone formation or both. The net result of these activities is profound skeletal destruction that can have dire consequences for patients. The molecular mechanisms that underlie these painful and often incurable consequences of tumor metastasis to bone are beginning to be recognized, and they represent promising new molecular targets for therapy.

The promise of bone cancer proteomics

Mass spectrometric analysis of the low-molecular-weight (LMW) range of the serum/plasma proteome is revealing the existence of large numbers of previously unknown peptides and protein fragments, predicted to be derived from circulating low-abundance proteins. While genomics and proteomics are the primary discovery research tool, recent innovations in high-throughput proteomics are now standard practice for biomarker and target discovery. Surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS) is the current mainstay for serum or plasma analysis, although other methods are emerging as alternative high-throughput approaches. From a proteomics perspective, the bone cancers, such as myeloma, breast and prostate cancer bony metastases, and osteosarcoma, are likely among the least studied. As recent advances in proteomic technology have thrust the bone cancer field into the era of proteomics, a review of the current status of the proteome as it relates to the skeletal consequences of malignancy seems reasonable.

Gene therapy to enhance allograft incorporation after host tissue irradiation

Structural bone allografts are used to reconstruct large skeletal defects after tumor surgery. Although allograft-related complications are declining, the use of perioperative radiation therapy is associated with a poorer outcome. Recently, BMP-2 levels in the host bed were reportedly diminished after exposure to radiation doses consistent with those used perioperatively to treat musculoskeletal sarcoma. Reintroduction of this osteogenic protein may circumvent the deleterious effects of preoperative radiation on allograft incorporation. We introduced a novel polymeric BMP-2 gene delivery system into the host-allograft junctions at the time of transplantation in an ovine tibial defect model with or without preoperative exposure to 50 Gy radiation. After 4 months, we noted no radiographic or histologic improvements in allograft incorporation after preoperative radiation and BMP-2 reintroduction; however, 50 Gy radiation was associated with increased porosity in the interface regions and poorer radiographic healing. We identified no BMP2-expressing cells or protein in the interface at the study end point, suggesting the polymeric gene delivery system was unable to promote extended expression of the protein or induce a healing response. Although gene therapy may hold promise as a novel technique to improve allograft incorporation, our data do not support that contention with the current approach.

Partners in research: benefits of a summer research program

BACKGROUND

The Partners in Research program provides first-hand research experiences for medical, pharmacy, and African-American undergraduate students.

METHODS

During ten weeks, students participate in on-going cancer research, weekly educational sessions, two observational clinic sessions, and at least one patient support-community outreach clinic.

RESULTS

Over the past six years the program has enrolled 155 students. Surveys indicate that most students give the course high ratings and would recommend the course to their peers. Follow-up shows their continued interest in research.

CONCLUSIONS

The program will encourage students to pursue careers in cancer research and provide a solid base of knowledge to future health care professionals.

Evidence for telomeric fusions as a mechanism for recurring structural aberrations of chromosome 11 in giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a benign but often aggressive tumor with a tendency toward local recurrence. Telomeric associations (tas) or telomeric fusions are common cytogenetic findings that have been implicated in the initiation of chromosome instability and tumorigenesis. We performed cytogenetic studies on 5 cases of GCTB to further characterize chromosome aberrations in these tumors. Four of the 5 cases showed abnormal karyotypes with clonal telomeric fusions involving chromosome 11. In 3 cases, the telomeric fusions of 11pter were apparently the precursor lesions to the progression of sub-clones with structural chromosome aberrations of 11p. Two tumors demonstrated a similar pattern of progression resulting in whole arm losses of 11p, including sub-clones with both whole-arm unbalanced translocations and whole-arm deletions. A third tumor with clonal tas of 11pter showed 2 additional subclones, one with ring chromosome 11 and the other with an extra copy of 1q. To our knowledge, the 2 cases with del(11)(p11) represent the first report of a recurring structural chromosome aberration in GCTB. These findings support the concept that telomeric instability is responsible for a large degree of intratumor heterogeneity and serves as a precursor lesion to subsequent clonal structural aberrations of chromosome 11 in GCTB.

The effect of host tissue irradiation on large-segment allograft incorporation

Therapeutic radiation delivered to bone and the adjacent local tissues before allograft limb-salvage surgery has been associated with poor graft incorporation and higher numbers of clinical complications. Our objective was to determine the effect of preoperative radiation therapy on specific histologic, molecular and structural parameters of large-segment, bone allograft incorporation in a canine model. Skeletally mature dogs received a total of 0, 25, or 50 Gy of radiation to the foreleg (radius and ulna) delivered in 2-Gy fractions during a 5-week period before reconstruction of a 3.5-cm defect in the radius. The dogs were sacrificed at postoperative day 150. Nondestructive four-point bending was done on the harvested allograft-host bone immediately after euthanasia and specimens were compared using biomechanical, histomorphometric, immunohistochemical, and in situ reverse transcription polymerase chain reaction techniques. Preoperative irradiation significantly impaired allograft incorporation as determined by radiographic healing scores, histomorphometry, and frequency of nonunions. Biochemical differences included diminished bone morphogenetic protein-2 and bone morphogenetic protein-4 protein levels and messenger ribonucleic acid expression. Vascular endothelial growth factor expression was not altered. These data suggest that bone morphogenetic protein-2 and bone morphogenetic protein-4 signaling at the allograft-host junction is altered after preoperative fractionated radiation and provides a plausible albeit partial mechanistic explanation for radiation-mediated delays in allograft incorporation.

A clonal reciprocal t(2;7)(p13;p13) in plantar fibromatosis

Cytogenetic reports of plantar fibromatosis are rare, and to our knowledge no clonal reciprocal translocations have been reported in these lesions. Reciprocal chromosome translocations have been identified in a number of solid tumors and in some cases have helped identify genes involved in their pathogenesis. We report a case of plantar fibromatosis with the novel finding of a t(2;7)(p13;p13) balanced reciprocal translocation as the sole cytogenetic abnormality.

A reciprocal t(4;9)(q31;p22) in a solitary neurofibroma

Cytogenetic reports of solitary neurofibromas are rare and, to our knowledge, no clonal reciprocal translocations have been reported in these tumors. Reciprocal chromosome translocations have been identified in a number of solid tumors and can have both diagnostic and prognostic significance. We report the first case of a solitary circumscribed neurofibroma with a (4;9)(q31;p22) balanced reciprocal translocation as the sole cytogenetic abnormality.

A novel t(X;2)(q13;q35) in clear cell sugar tumor of bone

Reciprocal translocations have been identified in a number of solid tumors and can serve as both diagnostic and prognostic indicators. When these translocations occur as the primary or sole chromosome aberration, they can potentially be associated with the formation of tumor-specific fusion genes at the translocation breakpoints. We present what is to our knowledge the first reported case of a primary clear cell sugar tumor of bone displaying a novel t(X;2)(q13;q35) as the sole cytogenetic aberration.

Breast cancer metastasis to bone: it is not all about PTHrP

Breast cancer shows a predilection for metastasis to bone. Interestingly, approximately 80% of patients with breast cancer also have bone metastases develop at some point during the course of their disease. Osteolytic breast cancer induces bonedestruction via the stimulation of osteoclasts. Breast cancer cells produce many known stimulators of bone resorption with significant research effort focused on the role of parathyroid hormone-related protein (PTHrP). However, a recent prospective clinical trial has questioned the primary role of PTHrP in this process. The overexpression of interleukin-8 (IL-8) in metastatic breast cancer cells prompted additional investigation of the role of IL-8 in osteolysis. Recombinant IL-8 induces the expression of RANKL mRNA and protein in osteoblastic cells and stimulates formation of bone resorbing osteoclasts, even in the absence of RANKL. The ability of IL-8 to directly stimulate osteoclastogenesis via RANKL dependent and independent mechanisms suggests it may play an important role in the process of osteoclast formation and function. Therefore, we propose that cytokines such as IL-8 are involved in the early stages of breast cancer metastasis and initiate the process of osteoclastic bone resorption. In this modified model of breast cancer metastasis to bone, PTHrP expression is induced later to stimulate the vicious cycle of bone destruction.

Recurring breakpoints of 1p13 approximately p22 in osteochondroma

Cytogenetic studies of osteochondromas are scarce but have previously shown recurring clonal aberrations involving chromosome 8. We have studied a series of eight tumors and have found recurring aberrations not only involving chromosome 8, but also chromosome 1 in five of the seven abnormal tumors. Surprisingly, three of the chromosome 1 aberrations involved pericentric inversions. Four tumors showed aberrations involving the region 1p13 approximately p22 by mechanisms including inversion, insertion, and translocation. These findings indicate that aberrations of chromosome 1p, in a region spanning 1p13 approximately p22, may be nonrandomly involved in the cytogenetic progression of osteochondroma.

Expression of interleukin 8 and not parathyroid hormone-related protein by human breast cancer cells correlates with bone metastasis in vivo

Metastasis is the process by which tumor cells spread from their site of origin to distant sites after gaining access to the circulatory system. An understanding of the factors contributing to the metastatic potential of breast cancer cells to bone will enhance the prospect of developing new therapies that impede metastasis. In this study, we have used an in vivo selection scheme involving left cardiac ventricle injection into nude mice to identify a highly metastatic human breast cancer cell line (MDA-MET) from a less metastatic (MDA-231) parental cell line. In this model, tumor-bearing mice exhibit features similar to those associated with human metastatic bone disease such as osteolytic bone destruction. After inoculation, MDA-MET cells form devastating lesions within 4 weeks, whereas the parental cells do not, even after 10 weeks. In vitro, the MDA-MET cells have a similar growth rate to the parental MDA-231 cells yet demonstrate distinct adhesive and invasive phenotypes. MDA-MET cells show increased early adhesion to type IV collagen and are significantly more invasive through Matrigel than MDA-231 cells. Analysis of the gene expression profile in the metastatic MDA-MET versus poorly metastatic MDA-231 cells identified relatively few genes whose expression was altered >2-fold. Of particular interest was the lack of parathyroid hormone-related protein (PTHrP) mRNA expression, which was supported at the protein level by immunoradiometric assay. These data support the idea that PTHrP is not predictive of the metastasis of human breast cancer to bone. Another important difference between the two cell lines was the elevated expression by MDA-MET cells of the cytokine IL-8. Reverse transcriptase-PCR and ELISA confirmed the increased expression of IL-8 in MDA-MET cells. In addition, IL-8 mRNA expression is also elevated in a variety of human cancer cell lines with different metastatic potential in vivo. These experiments suggest that the elevated expression of IL-8 (and not PTHrP) by MDA-MET cells is a phenotypic change that may be related to their enhanced ability to metastasize to the skeleton.

Local progression after operative treatment of metastatic kidney cancer

The cases of 78 patients with osseous metastases from kidney cancer were reviewed to determine the rate of local progression after operative resection as compared with more traditional intralesional procedures. Group I consisted of 41 (53%) patients who were treated with intralesional procedures involving internal fixation with or without curettage or polymethylmethacrylate. Of the 41 patients, additional operations were recommended for 17 (41%) of the patients who had local osseous progression. Fourteen additional procedures including nine wide resections with reconstruction, three amputations, and two mass excisions were done. Group II consisted of 37 (47%) patients who were treated with marginal or wide resection with or without reconstruction. In this group, only one patient required additional operative intervention for local osseous progression. Median survival of patients in Group I was 20 months compared with 35 months for patients in Group IL This study shows that despite shorter average survival, patients who undergo intralesional surgery are at high risk of reoperation for local progression. Resectional surgery should be considered in patients with skeletal metastases from kidney cancer to lessen the risk of reoperation for local progression.

A novel reciprocal (10;17)(p11.2;q23) in myxoid fibrosarcoma

Recurring reciprocal translocations have been identified as the primary chromosome aberrations in a number of neoplasms. These aberrations are often closely associated with particular morphologic or phenotypic subtypes of tumors and in some cases have prognostic implications. We have identified a novel reciprocal t(10;17)(p11.2;q23) in a case of low-grade myxoid fibrosarcoma, which may prove to be a new tumor specific chromosome aberration.

Apoptosis of osteocytes in glucocorticoid-induced osteonecrosis of the hip

An increase in osteoblast and osteocyte apoptosis has been demonstrated in mice and humans receiving glucocorticoids and may be involved in the pathogenesis of the associated osteonecrosis. To examine the spatial relationship between osteocyte apoptosis and glucocorticoid-induced osteonecrosis, we determined the prevalence of osteocyte apoptosis in whole femoral heads obtained from patients who underwent prosthetic hip replacement because of osteonecrosis due to chronic glucocorticoid treatment (n = 5), alcoholism (n = 3), and trauma (n = 1) as well as in femoral neck cores from patients with sickle cell disease (n = 5). Abundant apoptotic osteocytes and cells lining cancellous bone were found juxtaposed to the subchondral fracture crescent in femurs from the patients with glucocorticoid excess. In contrast, apoptotic bone cells were absent from the specimens taken from patients with trauma or sickle cell disease and were rare with alcohol abuse. These results indicate that glucocorticoid-induced osteonecrosis is a misnomer. The bone is not necrotic; instead, it shows prominent apoptosis of cancellous lining cells and osteocytes. Glucocorticoid-induced osteocyte apoptosis, a cumulative and irreparable defect, could uniquely disrupt the mechanosensory function of the osteocyte network and thus start the inexorable sequence of events leading to collapse of the femoral head.

Orthopaedic management of chronic pain: pain management for the cancer patient

Chronic pain is best managed through a multidisciplinary approach, which includes traditional and nontraditional therapies. Orthopaedists probably deal with chronic pain patients more than any other medical specialists. As Foley points out, it is critical that a trusting relationship between the patient and the physician is established; a relationship in which the patient believes the physician is taking the pain symptoms seriously and intends to address the pain aggressively. Although dealing with chronic pain can be a very frustrating part of orthopaedic practice, it can also be seen as a challenge.

Effect of methotrexate on distraction osteogenesis

To assess the potential of using distraction osteogenesis to reconstruct bone deficient limbs after limb salvage for musculoskeletal sarcomas, the authors examined the effect of methotrexate on distraction osteogenesis in a rabbit tibial lengthening model. Eighteen rabbits underwent tibial corticotomy and application of a ring external fixator. Rabbits were assigned randomly to one of two groups in which either methotrexate (n = 12) or placebo (n = 6) was administered during a 21-day distraction period. Serum methotrexate levels and complete blood cell counts were monitored during distraction, and radiographs of the tibia were obtained weekly. Half of the animals from each group were sacrificed at the end of distraction, and the remaining animals were sacrificed after 6 weeks of neutral fixation when bone normally bridges the gap. Using methotrexate at serum concentrations similar to those used clinically for the treatment of human osteosarcomas, the authors were unable to show significant radiographic, histologic, or chemical differences in the effect of this antineoplastic drug on distraction osteogenesis in the rabbit model.

Evidence of an association between 6q13-21 chromosome aberrations and locally aggressive behavior in patients with cartilage tumors

BACKGROUND

The finding of a cytogenetic-pathologic correlation between complex karyotypes and high grade cartilaginous tumors has been reported. However, few cytogenetic reports exist regarding benign or low grade lesions. A subset of low grade malignant cartilaginous tumors is characterized by locally aggressive behavior but no metastatic potential. Because the histopathologic distinction between benign, borderline, or low grade malignant cartilaginous lesions can be difficult, the finding of additional tumor markers associated with the clinical behavior of borderline cartilaginous lesions could be clinically significant.

METHODS

Four cartilaginous tumors, including an osteochondroma (OC), a chondromyxoid fibroma (CF), an enchondroma (EC), and a dedifferentiated chondrosarcoma (DCS), were cultured and harvested using short term, in situ culture techniques. Chromosome analysis was performed by conventional G-banding and fluorescence in situ hybridization was used to confirm G-banding.

RESULTS

The stemlines of all four tumors showed multiple chromosome anomalies that included aberrations of 6q13-21. The OC showed a t(6;16)(q21;p13.3). The CF showed a complex rearrangement between the chromosome 6 homologues, resulting in an inv(6)(p25q23)t(6;6)(q23;q13). This tumor also showed the clonal evolution of telomeric associations resulting in duplications, deletions, and the formation of a ring 15. The EC showed a der(6)t(6;15)(q13;q11)t(15;22)(q22;q13) stemline and subclones with an unstable iso 17q that subsequently fused to both ends of chromosome 16. The DCS showed a del(6)(q13), r(9), +12 stemline.

CONCLUSIONS

The cytogenetic findings of this study suggest the cytogenetic-pathologic correlation of complex karyotypes found in high grade cartilage tumors may extend to lower grade tumors with complex karyotypes. These findings further suggest that chromosome aberrations in the region of 6q13-21 may be associated with locally aggressive behavior in patients with cartilage tumors.

Myositis ossificans: an unusual presentation in the foot

Myositis ossificans is a non-neoplastic lesion characterized by heterotopic ossification of soft tissue. At varying stages of maturity, it shares similar histologic characteristics with sarcomatous lesions or maturing bone. Misdiagnosis can result in unnecessary radical treatment. This lesion has only rarely been reported in the foot. We present the case of a patient with plantar forefoot myositis ossificans.

Biomechanical analysis of patellar tendon allografts as a function of donor age

We evaluated the biomechanical properties of patellar tendon allografts from donors aged 18 to 55 years. Bone-patellar tendon-bone complexes were harvested from acceptable donors and processed. Fat and soft tissue were removed, and the tendons were sectioned lengthwise leaving the central third. Area measurements were taken, and mechanical testing was performed. Specimens were pulled to failure at a rate of 10% of the initial length per second. The force at failure, tensile stress, modulus of elasticity, and percent elongation were determined for each specimen. There was no significant correlation (P > 0.05) between age and any of the mechanical properties. Load at failure ranged from 2110 to 4650 N, with a mean of 3424 N. Regression analysis showed slightly decreasing tensile stress with increasing age, but the correlation was not significant. It appears that patellar tendon allografts from donors up to age 55 have similar mechanical properties.

Pullout strength of fixation screws from polymethylmethacrylate bone cement

Polymethylmethacrylate bone cement is often used to fill voids and increase the strength of osteoporotic and pathological bone. However, it is unclear as to which method of cement augmentation provides optimal screw fixation. This study was conducted to determine which of the current cement augmentation techniques provides the strongest construct when used in association with orthopaedic fixation screws. Pullout strength was determined for screws placed in sawbones with no cement, soft cement, doughy cement and hard cement after drilling and tapping. All cement-screw constructs were significantly stronger than the no cement group. Screws placed in doughy cement had a significantly higher pullout force than those placed in hard cement. Pullout strength of screws placed in soft cement was intermediate between the other cement techniques but not significantly different from either group.

Giant-cell tumor of bone: a rare entity in the hands of children

Giant-cell tumor of bone is a relatively uncommon tumor in skeletally immature patients. It also occurs only infrequently in the hand. We present two cases of this tumor occurring in the hands of pediatric patients and discuss the literature regarding this disease process, including clinical presentation, pathology, and options for treatment.

Granular tricalcium phosphate grafting of cavitary lesions in human bone

Development of an effective and safe bone grafting substitute could potentially alleviate many of the problems associated with human bone graft materials. Reported here are the results of 18 patients who were treated with a ceramic bone graft substitute, tricalcium phosphate. Twenty cavitary defects were created by intralesional curettage of a variety of benign bone neoplasms. Following complete removal of the tumor, each defect was filled with tricalcium phosphate granules. All patients were followed with periodic clinical and radiologic examinations for a minimum of 2 years (average followup of 37 months; range, 24 to 66 months). The amount of graft resorption and new bone formation were separately assessed on a percentage basis. Judged by radiographic criteria, the tricalcium phosphate implant lost its postoperative granular pattern in advance of bony trabeculae formation. Radiographic healing of defects with normal appearing bone was complete in four patients by 12 months, in an additional eight patients by 24 months, and in all except four patients by 48 months. Healing was dependent upon defect size; the larger lesions healing more slowly. Clinical parameters of healing were seen in advance of complete bone remodeling and all patients, except one, had unrestricted activity by 24 months. No adverse reactions were attributed to the graft material.

Case report 800: Skeletal fibrous dysplasia associated with intramuscular myxoma (Mazabraud's syndrome)

In summary, intramuscular myxoma associated with fibrous dysplasia of bone represents a benign disorder of uncertain etiology. Magnetic resonance imaging has proved to be a useful diagnostic tool in the evaluation of this benign disorder. In addition, MR is a valuable aid in the preoperative planning process.

Loose body of the elbow mimicking tumor

Distinguishing between calcific soft-tissue masses and intra-articular loose bodies about the elbow can be difficult. We present the case of a 59-year-old woman with a slowly enlarging soft-tissue mass about the elbow. History, physical examination, and diagnostic studies did not establish a definite diagnosis, nor did they rule out the possibility of a neoplastic process. Excisional biopsy revealed a loose body contained in a cystic mass with elbow joint communication.

Multifocal epithelioid hemangioendothelioma in bone

The case of a 17-year-old male with multifocal, grade I epithelioid hemangioendothelioma of the right ankle and foot is presented. The major symptom was poorly localized ankle pain refractory to conservative management. Imaging studies, including roentgenograms, computed tomographic scan, and magnetic resonance imaging, revealed multiple lesions in the right distal tibia, talus, calcaneus, and first cuneiform. An open biopsy of the right talus confirmed the diagnosis, and treatment consisted of localized radiation therapy to the affected area. We review the literature of this rare neoplasm from the initial descriptions to current nomenclatures and conceptualizations of the tumor.

Case report 731. Complicated Baker's cyst

The atypical appearance of a gas-containing, noninfected, popliteal synovial cyst has been presented. The case again demonstrates the value of plain radiographs, in this instance in distinguishing gas bubbles and calcification, which may not be apparent by MRI and ultrasound. The uniqueness of this case is stressed. The cause of the gas bubbles was not ascertained.

The effects of resection of the proximal part of the fibula on stability of the knee and on gait

We studied six patients to determine the effects of unilateral marginal resection of the proximal part of the fibula on stability of the knee and on gait. At the time of the operation, the fibular collateral ligament and the tendon of the biceps femoris were reattached, but no attempt was made to stabilize the fibula otherwise. The patients were tested an average of sixty-one months after operation. Stability of the knee was measured with an instrumented system. Gait was evaluated with an optical electronic three-dimensional digitizing system and a multicomponent force-platform. The gait of six healthy control subjects of similar age was also studied, and the reproducibility of measurements of stability of the knee was investigated in four healthy adults. There were significant differences between the side on which an operation had been done and the contralateral side with regard to the extent of anterior translation and of total anterior-posterior translation of the tibia at both 20 and 90 degrees of flexion of the knee, and in total varus and valgus rotation of the knee (the number of degrees from a position of maximum varus to one of maximum valgus angulation) at 20 degrees of flexion. The measurements of gait and of motion of the knee were found to be normal when compared with those in the control subjects. In the ground-reaction measurements, there were some significant differences from normal in the medial-lateral plane, but they were clinically unimportant. Resection of the proximal part of the fibula can lead to instability of the knee.

Skeletal reconstruction with allograft segments following bone tumor resection

The successful treatment of malignant neoplasms of bone requires surgical removal of the primary tumor. Limb salvage as an alternative to amputation requires surgical resection of the neoplasm with a wide margin and reconstruction of the segmental defect that is created. Transplantation of an allograft bone segment, with or without articular cartilage, is one option for reconstruction. The types of defects created and the types of reconstruction using segmental allografts are classified. Specific technical details involved in allograft reconstruction are discussed.

Telescoping intramedullary stabilization of the lower extremities for severe osteogenesis imperfecta

Intramedullary extendable Bailey-Dubow nails were used for treatment of lower extremity deformities resulting from osteogenesis imperfecta. Sixteen patients had 56 nails placed in 48 long bones, including 18 revisions. All patients were braced postoperatively. The average duration of follow-up was 4.8 years. Nine patients who were nonambulatory preoperatively walked in braces postoperatively. Despite a high rate of complication, extendable nails provide correction of the angular deformities of osteogenesis imperfecta, decrease fracturing, and allow most previously nonambulatory children to walk.