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Rotationplasty is an established technique that is indicated as part of the surgical reconstruction for certain patients with primary bone tumors around the knee who undergo tumor resection. There is considerable variation in the application of rotationplasty by surgeons as well as acceptance of the procedure by patients who may be candidates for this procedure. We qualitatively studied the decision-making process of families of patients who had undergone rotationplasty by interviewing 4 patients and their families using semi-structured interviews. Thematic analysis identified the following themes that were important in the decision-making process: (1) the desire for good information sources, (2) finding value in meeting with other patients who had been faced with a similar decision, (3) prioritizing function over cosmesis, (4) a desire to limit the need for revision surgeries, and (5) accepting that a return to normalcy is not an option with a surgery. Physicians and patients faced with a similar decision can benefit from a better understanding of the process, and by the normalization of anxieties and concerns that they may experience., Competing Interests: Declaration of Conflicting Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

Background: The complexity of sarcoma surgery often justifies surgical assistants of higher levels of academic training: senior residents, fellows, or co-surgeons. The association between the level of training of assistants and outcomes of these procedures has yet to be studied., Methods: The Current Procedural Terminology (CPT) codes comprising the "core" procedures for musculoskeletal oncology fellowships were gathered. After CPTs primarily capturing nononcologic procedures were excluded, the National Surgical Quality Improvement Program (NSQIP) database was used to find procedures with these CPTs. The severity of complications was assessed using the Severity Weighting of Postoperative Adverse Events in Orthopedic Surgery (SWORD) score. Resident/fellow presence was analyzed both as a binary variable and stratified by level of training., Results: In 159 cases meeting inclusion criteria, higher-level assistants were associated with increased rate of any complication ( p =0.006) and greater need for transfusion ( p =0.001) but also tended to be used in cases of longer duration ( p =0.001) and with higher total work relative value units (wRVUs) ( p =0.001). Multivariate analysis showed that while higher-wRVU procedures persisted as an independent predictor of increased complications (OR 1.028 per RVU unit, p =0.002), neither the presence nor level of training of assistants had an independent effect on complication rates. Other independent predictors of 30-day complications were treatment comorbidity (OR 3.433, p =0.010) and lower extremity location of the tumor (OR 4.393, p =0.006). Severity of complications did not differ between any of the groups on either univariate or multivariate analysis., Conclusions: Trainees of higher levels of academic training tend to be present for longer, higher-complexity musculoskeletal oncology cases, but the overall severity of complications from these do not significantly differ from lower-risk cases without trainees. Orthopedic oncologists may reassure patients that the presence of trainees and co-surgeons is not only safe but it may also help reduce the severity of complications in more complex procedures., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Eugene S. Jang et al.)

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor syndrome in which benign plexiform neurofibromas are at risk of transforming into malignant peripheral nerve sheath tumors (MPNSTs), a very rare soft-tissue sarcoma. The prognosis of patients with MPNSTs is poor, with most studies reporting <50% survival at five years. However, studies evaluating MPNSTs are limited and report heterogeneous results. Because no MPNST-specific evidence-based treatment guideline exists, individual institutional experiences are very informative to the field. The main objective of this study was to investigate and report MPNST prognostic clinical and genetic biomarkers from our institution's Orthopedics service experience treating 20 cases from 1992 to 2017. Most patients were treated with resection and adjuvant radiation. Extended follow-up, averaging 11.4 years (ranging 1.1 to 25.1), revealed excellent five-year survival rates: 70% for overall and 60% for metastatic disease. An S100 B immunonegative tumor phenotype was associated with a significantly worse outcome than MPNSTs with positive S100 B stain. In addition, NF1 gene mutation analysis was performed on 27 families with NF1 in which at least one affected family member developed MPNSTs. Of the 27 NF1 germline mutations, five were large deletions spanning (or nearly spanning) the gene (18.5%), substantially more than such deletions in NF1 in general, consistent with increased risk of MPNSTs in such cases., Competing Interests: The authors declare that there are no conflicts of interest with regard to this study., (Copyright © 2021 Daniel K. Knewitz et al.)

Brain metastases are a rare occurrence in patients with sarcoma. The prognosis for patients is poor, and treatment can contribute to considerable morbidity. We sought to examine the experience of our institution in managing these patients over a period of 17 years. We performed a retrospective cohort study of patients managed for sarcoma of the extremity or trunk who developed brain metastases from 2000 to 2017. Clinical data were analyzed and we assessed survival outcomes. 14 patients presenting at a mean age of 46.7 years were included. All patients were treated with radiotherapy for their brain metastases. 3 patients underwent surgical excision of their intracranial metastases. Two patients were treated with radium-223 dichloride. Kaplan-Meier survival analysis and the log rank test were used to calculate the survival probability, and to compare patient subgroups. All patients in this study developed lung or bone metastases at a mean interval of 13.3 months prior to the development of brain metastasis. The median interval from diagnosis of a brain metastasis to death was 3.6 months. The Kaplan-Meier survival probability at 6 months was 28.6%, and 14.3% at 1 year. Surgery was not found to be associated with increased survival. Patients with cerebellar metastasis had increased survival probability as compared to those with cerebral metastasis. Patients with extremity or trunk sarcoma who develop brain metastases frequently develop lung or bone metastases in the year preceding their diagnosis of brain metastasis. Patients with cerebellar metastasis may have better survival than those with cerebral metastasis, and an aggressive treatment approach should be considered. Despite aggressive treatment, the prognosis is grim., Competing Interests: Conflict of interest: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)

Background: The Patient Reported Outcomes Measurement Information System (PROMIS) is a tool developed by the National Institutes of Health that allows comparisons across conditions or even the United States (U.S.) general population., Objectives: Our purpose was to compare PROMIS outcomes between patients who underwent a planned resection to those who underwent an initial unplanned excision of their sarcoma followed by a definitive oncologic resection. We then compared these groups to the U.S. general population., Methods: Eighty-five patients were included and were divided into those who underwent an initial planned resection (67) and unplanned excision (18). These patients were then further categorized based on the length of follow-up since their last surgery, either early (<12 months) or late (>12 months)., Results: We evaluated seven PROMIS domains and found no differences between patients who underwent planned resection versus those who underwent an initial unplanned excision followed by a wide resection of the previous wound bed. When compared to the U.S. population, both cohorts demonstrated significantly improved scores in several emotional health domains., Conclusions: Patients who undergo an unplanned excision followed by a definitive oncologic procedure have similar PROMIS scores compared to patients who undergo an initial planned resection.

Background: Periosteal osteosarcoma is a rare surface-based variant with a lower propensity to metastasis and better prognosis than conventional osteosarcoma. The literature supporting survival benefit with adjuvant chemotherapy is lacking. Our institutional practice is for chemotherapy to be offered to patients with high-grade disease., Methods: We conducted a retrospective cohort study of patients managed for periosteal osteosarcoma from 1970 to 2015 analyzing the survival outcomes and assessing for any relationship of survival to patient- or treatment-related factors. 18 patients were included. The study population presented at a mean of 20.8 years and was followed for a mean of 10.7 years. Factors assessed for an association with survival included age, size of tumor, use of chemotherapy, presence of medullary involvement, presence of high-grade disease, local recurrence, and site of disease. Kaplan-Meier survival analysis and Cox proportional hazard regression were performed to calculate the survival rates and to assess for the effect of any factor on survival., Results: 10-year overall survival rate was 77.1%, and 10-year event-free survival rate was 66.4%. No factor was found to have an association with overall or event-free survival., Conclusion: These findings add to the available evidence which has failed to find any survival benefit from chemotherapy; patients with this rare disease and their families should be counselled regarding the unclear role of chemotherapy in this rare subtype of osteosarcoma.

Background: The most common site of sarcoma metastasis is the lung. Surgical resection of pulmonary metastases and chemotherapy are treatment options that have been employed, but many patients are poor candidates for these treatments for multiple host or tumor-related reasons. In this group of patients, radiation might provide a less morbid treatment alternative. We sought to evaluate the efficacy of radiotherapy in the treatment of metastatic sarcoma to the lung., Methods: Stereotactic body radiotherapy (SBRT) was used to treat 117 pulmonary metastases in 44 patients. Patients were followed with serial computed tomography imaging of the chest. The primary endpoint was failure of control of a pulmonary lesion as measured by continued growth. Radiation-associated complications were recorded., Results: The majority of patients (84%) received a total dose of 50 Gy per metastatic nodule utilizing an image-guided SBRT technique. The median interval follow-up was 14.2 months (range 1.6-98.6 months). Overall survival was 82% at two years and 50% at five years. Of 117 metastatic nodules treated, six nodules showed failure of treatment (95% control rate). Twenty patients (27%) developed new metastatic lesions and underwent further SBRT. The side effects of SBRT included transient radiation pneumonitis ( n =6), cough ( n =2), rib fracture ( n =1), chronic pain ( n =1), dermatitis ( n =1), and dyspnea ( n =1)., Conclusion: Stereotactic body radiotherapy is an effective and safe treatment for the ablation of pulmonary metastasis from sarcoma. Further work is needed to evaluate the optimal role of SBRT relative to surgery or chemotherapy for treatment of metastatic sarcoma.

Background: Parosteal osteosarcoma is a rare tumor with increased survival compared to conventional high-grade osteosarcoma. Due to this increased survival comes the need for reconstructive options that provide good long-term functional results. Current treatment methods include geographic resection with allograft reconstruction versus resection and reconstruction with a distal femoral replacement., Purpose: Our purpose was to compare the long-term functional outcomes of distal femoral replacements to allograft reconstructions, using the musculoskeletal tumor society (MSTS) scoring system., Methods: After querying our database, 12 patients were identified and completed a MSTS questionnaire., Results: There was no difference in functional outcomes between the cohorts at an average of 14 years follow up for the endoprosthetic group and 25 years of follow up for the geographic resection group., Conclusion: At long-term follow-up, patients who undergo a distal femoral replacement for a parosteal osteosarcoma have no difference in functional outcomes compared to those who undergo an allograft reconstruction.Level of Evidence: IV.

Purpose: To review the treatment and outcomes of patients with mesenchymal chondrosarcomas (MC)., Materials and Methods: Review of the pertinent literature., Results: MC is a rare aggressive small round blue cell malignancy that may arise in either bone or soft tissue. It usually presents in the 2 nd or 3 rd decade of life and exhibits an approximately equal gender predilection. Patients usually present with pain and swelling. The majority of MCs arise in either the trunk or extremities. Distant metastases are present at diagnosis in about 15% of patients. The most common sites for distant metastases are lung and bone. The optimal treatment is surgery. Although the role of adjuvant chemotherapy is unclear, an anthracycline-based chemotherapy regimen combined with ifosfamide or cisplatin, may be considered. Adjuvant radiation therapy (RT) is employed for patients with close (<5 mm) or positive margins as well as those with incompletely resectable tumors. The most common mechanism of recurrence is hematogenous dissemination. Although most recurrences are observed within 5 years of treatment, late recurrences are not unusual. The likelihood of successful salvage in the event of a recurrence is modest. The overall survival rates for all patients are approximately 50% at 5 years and 40% at 10 years. The overall survival rates for the subset of patients with localized disease that is resected are approximately 70% to 80% at 5 years and 60% at 10 years., Conclusion: Patients with MCs are optimally treated with surgery. The role of adjuvant chemotherapy is uncertain. However, given the relatively high risk of recurrence, adjuvant chemotherapy should be considered in medically fit patients. Radiation therapy should be considered for those with incompletely resectable tumors and those with inadequate margins., Competing Interests: Conflicts of interest: The authors have no conflicts of interest to disclose., (© Copyright 2016 International Journal of Particle Therapy.)

Background: Pulmonary surveillance protocols following sarcoma excision based on clinical evidence and outcomes are limited in current literature. The purpose of this study was to determine the method, frequency, and reasoning behind pulmonary surveillance strategies in patients treated for sarcoma among members of the Musculoskeletal Tumor Society (MSTS)., Methods: SurveyMonkey, an online survey tool, was used to create and distribute a questionnaire to 211 members of the MSTS in 2011. The 16 questions focused on current pulmonary surveillance algorithms and their reasoning., Results: Of the surveyed members of the MSTS, 65% follow high-grade sarcoma with routine chest CT scans. Most disagreement involved low-grade sarcomas, where radiographs (34%), routine CT (33%), or selective CT scans (31%) were evenly distributed. Selective CT scans in low-grade lesions were warranted with an indeterminate nodule on prior CT (81%), local recurrence (40%), or large/ deep tumor characteristics (31%). Most protocols were based on continuation of training protocols (46%), clinician's interpretation of the current literature (23%), or personal experience (14%)., Conclusions: Significant clinician variability exists in terms of pulmonary surveillance of sarcomas, most notably in low-grade lesions. The results of this study represent an area in need of further study to develop an evidence-based protocol for sarcoma pulmonary surveillance.

Background: Extraskeletal osteosarcoma is a rare tumor with a poor prognosis. The purpose of this study is to examine the oncologic outcomes of this disease as they relate to surgical treatment and use of adjuvant therapies., Methods: We retrospectively analyzed all patients treated at our institution for high-grade extraskeletal osteosarcoma of the limb or chest wall. We recorded demographic data, presenting stage, surgical margin, use of adjuvant chemotherapy or radiation, incidence of local recurrence, metastases, and death. Overall and event-free survival were calculated using Kaplan-Meier survival methods., Results: There were 12 patients treated with primary wide resection or re-excision of a previously operated tumor bed. Four patients presented with metastases. Seven patients received chemotherapy and four patients received radiation therapy. There were two local recurrences, six patients developed new metastases, and nine patients died. There was no difference in overall survival in patients who received chemotherapy. There was, however, a trend towards increased length of survival in patients who received chemotherapy compared to those who did not (16.4 months vs. 9.3 months, p=0.16)., Conclusions: Despite no difference in overall survival, patients treated with adjuvant chemotherapy have a trend towards increased length of survival. We suggest that extraskeletal osteosarcoma be treated with standard osteosarcoma chemotherapy regimens in addition to wide resection.

Background: A giant cell tumor is a benign locally aggressive tumor commonly seen in the distal radius with reported recurrence rates higher than tumors at other sites. The dilemma for the treating surgeon is deciding whether intralesional treatment is adequate compared with resection of the primary tumor for oncologic and functional outcomes. More information would be helpful to guide shared decision-making., Questions/purposes: We asked: (1) How will validated functional scores, ROM, and strength differ between resection versus intralesional excision for a giant cell tumor of the distal radius? (2) How will recurrence rate and reoperation differ between these types of treatments? (3) What are the complications resulting in reoperation after intralesional excision and resection procedures? (4) Is there a difference in functional outcome in treating a primary versus recurrent giant cell tumor with a resection arthrodesis?, Methods: Between 1985 and 2008, 39 patients (39 wrists) were treated for primary giant cell tumor of the distal radius at two academic centers. Twenty patients underwent primary intralesional excision, typically in cases where bony architecture and cortical thickness were preserved, 15 underwent resection with radiocarpal arthrodesis, and four had resection with osteoarticular allograft. Resection regardless of reconstruction type was favored in cases with marked cortical expansion. A specific evaluation for purposes of the study with radiographs, ROM, grip strength, and pain and functional scores was performed at a minimum of 1 year for 21 patients (54%) and an additional 11 patients (28%) were available only by phone. We also assessed reoperations for recurrence and other complications via chart review., Results: With the numbers available, there were no differences in pain or functional scores or grip strength between groups; however, there was greater supination in the intralesional excision group (p=0.037). Tumors recurred in six of 17 wrists after intralesional excision and none of the 15 after en bloc resection (p=0.030). There was no relationship between tumor grade and recurrence. There were 12 reoperations in eight of 17 patients in the intralesional excision group but only one of 11 patients (p=0.049) who underwent resection arthrodesis with distal radius allograft had a reoperation. There were no differences in functional scores whether resection arthrodesis was performed as the primary procedure or to treat recurrence after intralesional excision., Conclusions: Resection for giant cell tumor of the distal radius with distal radius allograft arthrodesis showed a lower recurrence rate, lower reoperation rate, and no apparent differences in functional outcome compared with joint salvage with intralesional excision. Because an arthrodesis for recurrence after intralesional procedures seems to function well, we believe that intralesional excision is reasonable to consider for initial treatment, but the patient should be informed about the relative benefits and risks of both options during the shared decision-making process. Because arthrodesis after recurrence functions similar to the initial resection and arthrodesis, an initial treatment with curettage remains a viable, and likely the standard, mode of treatment for most giant cell tumors of the distal radius unless there is extensive bone loss., Level of Evidence: Level III, therapeutic study.

Context: Intramuscular hemangiomas are common in the general population and often present at medical and surgical clinics. Unfortunately, unfamiliarity with these lesions has led to a high percentage of misdiagnoses, inappropriate workup, and unnecessary referrals., Evidence Acquisition: A literature search was performed using Medline, Embase, PubMed, and Cochrane. The relevant articles and referenced sources were reviewed for additional articles that discussed the epidemiology, pathophysiology, investigation, and management of intramuscular hemangiomas. Clinical experience from experts in orthopaedics, musculoskeletal pathology, and musculoskeletal radiology was compared. The selected case studies are shared cases of the authors., Results and Conclusion: The pathophysiology of these lesions is not completely understood, but much can be implied from their underlying vascular nature. Isolated lesions are benign tumors that never metastasize but tend to enlarge and then involute over time. Magnetic resonance imaging is the imaging modality of choice. If a systemic disorder or malignancy is not suspected or has been ruled out, conservative management is the treatment of choice for most intramuscular hemangiomas.

Soft tissue sarcoma is a rare malignancy, with approximately 11,000 cases per year encountered in the United States. It is primarily encountered in adults but can affect patients of any age. There are many histologic subtypes and the malignancy can be low or high grade. Appropriate staging work up includes a physical exam, advanced imaging, and a carefully planned biopsy. This information is then used to guide the discussion of definitive treatment of the tumor which typically involves surgical resection with a negative margin in addition to neoadjuvant or adjuvant external beam radiation. Advances in imaging and radiation therapy have made limb salvage surgery the standard of care, with local control rates greater than 90% in most modern series. Currently, the role of chemotherapy is not well defined and this treatment is typically reserved for patients with metastatic or recurrent disease and for certain histologic subtypes. The goal of this paper is to review the current state of the art in multidisciplinary management of soft tissue sarcoma.

Introduction: Chondrosarcoma is well-known to be primarily resistant to conventional radiation and chemotherapy., Case Presentation: We present the case of a 32-year-old Caucasian man with clear cell chondrosarcoma who presented with symptomatic recurrence in his pelvis and metastases to his skull and lungs. Our patient underwent systemic therapy with sunitinib and then consolidation with proton beam radiation to his symptomatic site. He achieved complete symptomatic relief with a significantly improved performance status and had an almost complete and durable metabolic response on fluorine-18-fluorodeoxyglucose positron emission tomography., Conclusions: Our findings have important clinical implications and suggest novel clinical trials for this difficult to treat disease.

Chest CT scans are often used to monitor patients after excision of a sarcoma. Although sensitive, CT scans are more expensive than chest radiographs and are associated with possible health risks from a higher radiation dose. We hypothesized that a program based upon limited CT scans in lower-grade sarcoma could be efficacious and less expensive. We retrospectively assigned patients to a high-risk or low-risk hypothetical protocol. Eighty-three low- or intermediate-grade soft tissue sarcomas met our inclusion criteria. Eight patients had pulmonary metastasis. A protocol based on selective CT scans for high-risk patients would have identified seven out of eight lesions. The incremental cost-effectiveness ratio for routine CT scans was $731,400. A program based upon selective CT scans for higher-risk patients is accurate, spares unnecessary radiation to many patients, and is less expensive.

Background: Complications are frequent with osteoarticular allografts, and their long-term survivorship in the distal femur is unclear. Thus, the benefits of osteoarticular allografting remain controversial., Questions/purposes: We therefore determined the frequency of complications in osteoarticular allografts of the distal femur relative to their potential long-term survival., Methods: We retrospectively reviewed 26 patients who had osteoarticular allograft reconstruction of the distal femur after resection of a malignant or aggressive benign tumor of bone. The minimum followup was 15 months (average, 156 months; range, 15-283 months) for all patients and 98 months (average, 191 months; range, 98-283 months) for the surviving patients., Results: At last followup, 16 of the 26 original allografts were still in place. The overall 5-year and 10-year allograft survival rates were 69% and 63%, respectively. The 5-year and 10-year survival rates of the joint surface were 79% and 65%, respectively. Eleven patients retained their original osteoarticular allograft without a resurfacing procedure, and nine had been converted to allograft-prosthetic composites. Five patients were converted to megaprostheses and one had an amputation for local recurrence. At last followup, 25 of 26 patients retained a functional limb., Conclusions: Osteoarticular allograft reconstructions of the distal femur can provide long term survival and restore function but the risk of complications and their physical and monetary costs for patients are not trivial. Lacking the benefit of improved soft tissue attachments inherent in other anatomic sites, we believe this option is most appropriate for restoring bone stock in young patients with expectations of long-term survival.

Soft-tissue sarcoma (STS) is a histopathologically diverse group of tumors accounting for approximately 10,000 new malignancies in the US each year. The proximal lower extremity is the most common site for STS, accounting for approximately one-third of all cases. Coordinated multimodality management in the form of surgery and radiation is often critical to local control, limb preservation, and functional outcome. Based on a review of currently available Medline literature and professional experience, this paper provides an overview of the treatment of STS of the lower extremity with a particular focus on the modern role of radiotherapy.

Disuse atrophy is a common clinical phenomenon that significantly impacts muscle function and activities of daily living. The purpose of this study was to implement genome-wide expression profiling to identify transcriptional pathways associated with muscle remodeling in a clinical model of disuse. Skeletal muscle biopsies were acquired from the medial gastrocnemius in patients with an ankle fracture and from healthy volunteers subjected to 4-11 days of cast immobilization. We identified 277 misregulated transcripts in immobilized muscles of patients, of which the majority were downregulated. The most broadly affected pathways were involved in energy metabolism, mitochondrial function, and cell cycle regulation. We also found decreased expression in genes encoding proteolytic proteins, calpain-3 and calpastatin, and members of the myostatin and IGF-I pathway. Only 26 genes showed increased expression in immobilized muscles, including apolipoprotein (APOD) and leptin receptor (LEPR). Upregulation of APOD (5.0-fold, P < 0.001) and LEPR (5.7-fold, P < 0.05) was confirmed by quantitative RT-PCR and immunohistochemistry. In addition, atrogin-1/MAFbx was found to be 2.4-fold upregulated (P < 0.005) by quantitative RT-PCR. Interestingly, 96% of the transcripts differentially regulated in immobilized limbs also showed the same trend of change in the contralateral legs of patients but not the contralateral legs of healthy volunteers. Information obtained in this study complements findings in animal models of disuse and provides important feedback for future clinical studies targeting the restoration of muscle function following limb disuse in humans.

Malignant peripheral nerve sheath tumors (MPNST) are the most aggressive cancers associated with neurofibromatosis type 1 (NF1). Here we report a practical and reproducible model of intraneural NF1 MPNST, by orthotopic xenograft of an immortal human NF1 tumor-derived Schwann cell line into the sciatic nerves of female scid mice. Intraneural injection of the cell line sNF96.2 consistently produced MPNST-like tumors that were highly cellular and showed extensive intraneural growth. These xenografts had a high proliferative index, were angiogenic, had significant mast cell infiltration and rapidly dominated the host nerve. The histopathology of engrafted intraneural tumors was consistent with that of human NF1 MPNST. Xenograft tumors were readily examined by magnetic resonance imaging, which also was used to assess tumor vascularity. In addition, the intraneural proliferation of sNF96.2 cell tumors was decreased in ovariectomized mice, while replacement of estrogen or progesterone restored tumor cell proliferation. This suggests a potential role for steroid hormones in supporting tumor cell growth of this MPNST cell line in vivo. The controlled orthotopic implantation of sNF96.2 cells provides for the precise initiation of intraneural MPNST-like tumors in a model system suitable for therapeutic interventions, including inhibitors of angiogenesis and further study of steroid hormone effects on tumor cell growth.

Cast immobilization is associated with decreases in muscle contractile area, specific force, and functional ability. The pathophysiological processes underlying the loss of specific force production as well as the role of metabolic alterations are not well understood. The aim of this study was to quantify changes in the resting energy-rich phosphate content and specific force production after immobilization. (31)P-magnetic resonance spectroscopy, three-dimensional magnetic resonance imaging, and isometric strength testing were performed in healthy subjects and patients with an ankle fracture after 7 wk of immobilization and during rehabilitation. Muscle biopsies were obtained in a subset of patients. After immobilization, there was a significant decrease in the specific plantar flexor torque and a significant increase in the inorganic phosphate (P(i)) concentration (P < 0.001) and the P(i)-to-phosphocreatine (PCr) ratio (P < 0.001). No significant change in the PCr content or basal pH was noted. During rehabilitation, both the P(i) content and the P(i)-to-PCr ratio decreased and specific torque increased, approaching control values after 10 wk of rehabilitation. Regression analysis showed an inverse relationship between the in vivo P(i) concentration and specific torque (r = 0.65, P < 0.01). In vitro force mechanics performed on skinned human muscle fibers demonstrated that varying the P(i) levels within the ranges observed across individuals in vivo (4-10 mM) changed force production by approximately 16%. In summary, our findings clearly depict a change in the resting energy-rich phosphate content of skeletal muscle with immobilization, which may negatively impact its force generation.

Adamantinoma of long bones is a rare neoplasm predominantly involving the tibia. Cytogenetic studies of adamantinoma are few. Cytogenetic or molecular cytogenetic analysis of four adamantinomas, and a review of eleven cases in the literature reveals extra copies of chromosomes 7, 8, 12, 19, and 21 as recurrent in this neoplasm. Adamantinoma may be confused with a variety of primary and metastatic epithelial and mesenchymal neoplasms. Observation of these aneuploidies may be useful in establishing the diagnosis of adamantinoma.