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Biomedical subjects

Mark T Scarborough

Publications and source records attributed to Mark T Scarborough.

At least 19 recordsLinked to original sources
PubMed2006

Deficit in human muscle strength with cast immobilization: contribution of inorganic phosphate.

Metabolic factors have been proposed to explain strength deficits observed in skeletal muscle with immobilization that are not completely accounted for by changes in muscle cross-sectional area (CSA) and neural adaptations. The aim of this study was to quantify changes in the resting inorganic phosphate (Pi) concentration from the medial gastrocnemius muscle during immobilization, reloading and rehabilitation. Additionally, we assessed the contributions of CSA, muscle activation and Pi concentration to plantar flexor torque during rehabilitation following immobilization. Eight persons with a surgically stabilized ankle fracture participated. Subjects were immobilized for 6-8 weeks and subsequently participated in 10 weeks of rehabilitation. Localized (31)P-Magnetic resonance spectroscopy, magnetic resonance imaging, isometric torque and activation testing were performed on the immobilized and uninvolved limbs. At 6 weeks of immobilization, significant differences were noted between the immobilized and uninvolved limbs for the Pi concentration and the Pi/PCr ratio (P < 0.05). From 6 weeks of immobilization to 3-5 days of reloading, the increase in Pi concentration (15%, P = 0.26) and Pi/PCr (20%, P = 0.29) was not significant. During rehabilitation, the relative contributions of CSA, muscle activation and Pi concentration to plantarflexor torque were 32, 44 and 40%, respectively. Together, CSA, muscle activation and Pi concentration accounted for 76% of the variance in torque (P < 0.01). In summary, our findings suggest that immobilization, independent of reloading, leads to a significant increase in the resting Pi concentration of human skeletal muscle. Additionally, alterations in resting Pi concentration may contribute to strength deficits with immobilization not accounted for by changes in muscle CSA or neural adaptations.

Adult↗
PubMed2006

Relative contributions of muscle activation and muscle size to plantarflexor torque during rehabilitation after immobilization.

Muscle atrophy is clearly related to a loss of muscle torque, but the reduction in muscle size cannot entirely account for the decrease in muscle torque. Reduced neural input to muscle has been proposed to account for much of the remaining torque deficits after disuse or immobilization. The purpose of this investigation was to assess the relative contributions of voluntary muscle activation failure and muscle atrophy to loss of plantarflexor muscle torque after immobilization. Nine subjects (ages 19-23) years with unilateral ankle malleolar fractures were treated by open reduction-internal fixation and 7 weeks of cast immobilization. Subjects participated in 10 weeks of rehabilitation that focused on both strength and endurance of the plantarflexors. Magnetic resonance imaging, isometric plantarflexor muscle torque and activation (interpolated twitch technique) measurements were performed at 0, 5, and 10 weeks of rehabilitation. Following immobilization, voluntary muscle activation (56.8 +/- 16.3%), maximal cross-sectional area (CSA) (35.3 +/- 7.6 cm(2)), and peak torque (26.2 +/- 12.7 N-m) were all significantly decreased ( p < 0.0056) compared to the uninvolved limb (98.0 +/- 2.3%, 48.0 +/- 6.8 cm(2), and 105.2 +/- 27.0 N-m, respectively). During 10 weeks of rehabilitation, muscle activation alone accounted for 56.1% of the variance in torque ( p < 0.01) and muscle CSA alone accounted for 35.5% of the variance in torque ( p < 0.01). Together, CSA and muscle activation accounted for 61.5% of the variance in torque ( p < 0.01). The greatest gains in muscle activation were made during the first 5 weeks of rehabilitation. Both increases in voluntary muscle activation and muscle hypertrophy contributed to the recovery in muscle strength following immobilization, with large gains in activation during the first 5 weeks of rehabilitation. In contrast, muscle CSA showed fairly comparable gains throughout both the early and later phase of rehabilitation.

Adult↗
PubMed2006

Giant cell tumor of bone.

OBJECTIVE: To discuss the treatment and outcomes for giant cell tumor (GCT) of bone. MATERIALS AND METHODS: Review of the pertinent literature. RESULTS: GCT is a rare benign bone lesion most often found in the extremities of women in the third and fourth decades of life. Surgery is the mainstay of treatment and usually consists of intralesional curettage; local control rates range from 80% to 90% after this procedure. Patients with extensive, recurrent, and/or biologically more aggressive tumors may require wide excision. A small subset of patients with incompletely resectable GCTs or with lesions that are surgically inaccessible may be treated with moderate-dose radiotherapy (45-50 Gy) and have a 65% to 80% likelihood of being locally controlled. CONCLUSION: The majority of patients with GCTs are effectively treated with intralesional curettage. Wide excision or radiotherapy is necessary to cure a relatively limited subset of patients with extensive, aggressive, and/or incompletely resectable GCTs.

Bone Neoplasms↗
PubMed2006

Adjuvant radiotherapy in the management of soft tissue sarcoma involving the distal extremities.

OBJECTIVE: Treating soft tissue sarcoma (STS) of the distal extremity is challenging in terms of achieving local control and avoiding complications. It is now accepted that a limb conserving approach provides equivalent survival when compared with radical amputation. METHODS: Twenty-three patients with STS involving the hand-wrist or foot-ankle complex received adjuvant radiotherapy (RT) for limb conservation and were evaluated to determine if local control, survival, and functional ability were achieved. The median patient age was 64 and median time of follow-up was 11 years. The location of the sarcoma included the hand (n = 12) or foot (n = 11). Seven patients received preoperative RT (median dose, 50.40 Gy) and 16 patients received postoperative RT (median dose, 64.80 Gy). Patients treated preoperatively and 9 treated postoperatively received hyperfractionated RT at 1.2 Gy twice-daily. Seven patients treated postoperatively received conventional daily-fractionated treatment. RESULTS: Twenty of 23 patients received RT at first presentation; 3 were treated for locally recurrent disease. The 5- and 10-year rates of local control were 91%. The 10-year rates of cause-specific and absolute survival were 96% and 91%, respectively. The 5- and 10-year rates of distant metastases-free survival were 87%. The ultimate limb-conservation rate was 91%. No patient required an amputation because of local recurrence or treatment complications. Function of the hand or foot was maintained for all of the 21 patients for whom limb-conserving treatment was achieved. CONCLUSIONS: Combined modality therapy with limb-conserving surgery and adjuvant RT achieves excellent local control (91%) and potential overall survival (91%) rates with excellent functional outcome.

Aged↗
PubMed2006

Aneurysmal bone cyst.

OBJECTIVES: The purpose of this article is to discuss the natural history, treatment, and outcomes for patients with aneurysmal bone cysts (ABC). METHODS: Review of the pertinent literature. RESULTS: ABCs account for 1% to 2% of all primary bone tumors, usually present in the first 2 decades of life, and exhibit a slight female preponderance. The majority of patients are treated with curettage with local control rates ranging from approximately 70% to 90%. Almost all patients with recurrences are salvaged by one or more additional operations. A small subset of patients is treated with marginal or wide excision and almost all are locally controlled. A few patients with incompletely resectable, aggressive, and/or recurrent ABCs are treated with low-dose (26-30 Gy) radiotherapy (RT) and are locally controlled in approximately 90% of cases. CONCLUSIONS: The mainstay of treatment is surgery and most patients are cured with one or more operations. A small subset of patients with incompletely resectable, aggressive, and/or recurrent ABCs may be cured with low-dose RT.

Bone Cysts, Aneurysmal↗
PubMed2006

Pigmented villonodular synovitis.

Pigmented villonodular synovitis (PVNS) is a rare proliferative disorder that affects the synovium in young and middle-aged adults. Although most believe that it is an inflammatory process, some believe that it is a benign neoplasm. The optimal treatment is surgery. The local recurrence rate after marginal excision for localized PVNS is low. In contrast, the local recurrence rate after open synovectomy for diffuse PVNS is relatively high. The intra-articular instillation of radioactive isotopes or external beam radiotherapy (approximately 35 Gy in 14-15 fractions over 3 weeks) may significantly improve the likelihood of local control and long-term function in patients with incompletely resected diffuse PVNS. The probability of complications after moderate-dose radiotherapy (RT) is low.

Brachytherapy↗
PubMed2005

Aggressive fibromatosis.

The purpose of this article is to review the pertinent literature and to define the optimal treatment of patients with aggressive fibromatosis. Data indicate the likelihood of local recurrence after surgery is high, particularly if margins are positive. Moderate-dose radiotherapy alone for gross disease or after a microscopically incomplete resection yields local control rates of approximately 75% to 80%. Treatment with pharmacologic agents results in objective response rates of approximately 40% to 50%; duration of response is variable. Thus, the optimal management for aggressive fibromatosis depends on tumor location and extent. Surgery is indicated if the lesion appears to be completely resectable with acceptable function and cosmesis. Radiotherapy is indicated for patients with unresectable tumors; those with positive margins after resection should be considered for adjuvant radiotherapy depending on the location and extent of the tumor. Pharmacologic treatment should be considered for patients with progressive disease after unsuccessful local-regional therapy.

Desmoid Tumors↗
PubMed2005

Radiotherapy in the treatment of dermatofibrosarcoma protuberans.

OBJECTIVE: To evaluate the role of postoperative radiotherapy (RT) for patients with dermatofibrosarcoma protuberans (DFSP). METHODS AND MATERIALS: Ten patients were treated with surgery and postoperative RT and had follow-up from 21 to 185 months. Nine patients had DFSP and 1 patient had a fibrosarcomatous component (DFSP-FS). No patient had gross disease at the time of RT. RESULTS: Nine patients with DFSP remained disease free after surgery and postoperative RT. The patient with DFSP-FS experienced a local recurrence after surgery, external beam RT, and a brachytherapy boost, and died with disease. There were no severe complications. CONCLUSION: Postoperative RT may reduce the risk of local recurrence in patients with DFSP who have a high risk of residual disease after surgery.

Adult↗
PubMed2004

Dermatofibrosarcoma protuberans.

In the current review, the authors set out to discuss the natural history and treatment of dermatofibrosarcoma protuberans (DFSP), a rare indolent cutaneous tumor. Approximately 10-15% of all DFSPs contain areas of fibrosarcoma (DFSP-FS), and such cases tend to exhibit more aggressive behavior. The optimal treatment for DFSP is resection with wide margins; the likelihood of local control associated with this procedure exceeds 90%. The probability of regional or distant metastases is </= 5%. Patients with positive or close surgical margins have an elevated risk of local recurrence after resection alone; however, postoperative radiotherapy results in local control rates of >/= 85% in such patients. Postoperative radiotherapy also is indicated in the rare event that a patient has unresectable macroscopic disease. Experience with the use of radiotherapy alone to treat macroscopic disease is limited.

Dermatofibrosarcoma↗
PubMed2004

Changes in inorganic phosphate and force production in human skeletal muscle after cast immobilization.

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.

Ankle Injuries↗
PubMed2004

Bone-forming tumors of the upper extremity and Ewing's sarcoma.

This article presents an overview of bone-forming tumors that occur in the upper extremity. Osteoid osteoma, osteoblastoma, osteosarcoma, and Ewing's sarcoma are covered. Each tumor type is described, and suggestions are made for diagnostic workup and differential diagnosis. Locations in the upper extremity where each tumor typically occurs are given. Preferred treatment regimens and incidence of recurrence are also presented.

Arm↗
PubMed2004

Giant cell tumor of the pelvis and sacrum: 17 cases and analysis of the literature.

The optimal treatment of giant cell tumors of the pelvis and sacrum is controversial. Our current patient series was combined with cases identified in a review of the literature published in the past 50 years, yielding a combined group of 239 lesions for study. Recurrence rates were 49% for patients who had radiation therapy alone, 47% for patients who had surgery with intralesional margins, 46% for patients who had surgery with intralesional margins and radiation therapy, and 0% for patients who had surgery with wide margins. Six percent of patients had benign lung metastases develop, 2% of patients had secondary malignancies, 2% of patients died in the perioperative period, and less than 1% of patients had multicentricity. Radiation-induced sarcoma developed in 11% of patients who received radiation for primary or recurrent lesions. Larger doses of radiation therapy did not decrease the rate of local recurrence. Recurrence after surgery and radiation was not lower than after either treatment alone. Local recurrence was more likely in the patients with sacral tumors (48%) than in the patients with pelvic tumors (34%). Disease status was worse in the patients with sacral lesions (23% died of disease) than in the patients with pelvic lesions (6% died of disease).

Adolescent↗
PubMed2004

Muscle adaptations with immobilization and rehabilitation after ankle fracture.

UNLABELLED: INTRODUCTION/ PURPOSE: The widespread occurrence of muscular atrophy during immobilization and its reversal presents an important challenge to rehabilitation medicine. We used 3D-magnetic resonance imaging (MRI) in patients with surgically-stabilized ankle mortise fractures to quantify changes in plantarflexor and dorsiflexor muscle size during immobilization and rehabilitation, as well as to evaluate changes in force generating capacity (specific torque). METHODS: Twenty-individuals participated in a 10 wk rehabilitation program after 7 wk of immobilization. MRIs were acquired at baseline, 2, and 7 wk of immobilization, and at 5 and 10 wk of rehabilitation. Isometric plantarflexor muscle strength testing was performed at 0, 5, and 10 wk of rehabilitation. RESULTS: Dorsiflexors and plantarflexors atrophied 18.9% and 24.4% respectively, the majority of which occurred during the first 2 wk of immobilization (dorsiflexors: 9.6%; plantarflexors: 14.1%). Likewise, more than 50% of hypertrophy during rehabilitation occurred within the first 5 wk of rehabilitation for both the dorsiflexors (12.9%) and plantarflexors (13.2%), when compared to the total amount of hypertrophy over 10 wk of rehabilitation (dorsiflexors: 17.6%, plantarflexors: 22.5%). There were no significant differences in hypertrophy or atrophy of the dorsiflexor or plantarflexor muscles, despite a rehabilitation emphasis on the plantarflexors. Patients had significantly lower plantarflexor specific torque (torque/CSA) than healthy, control subjects immediately after cast immobilization, which did not return to normal after 10 wk of rehabilitation (P < 0.05). CONCLUSION: Our investigation of the consequences of limb immobilization on rehabilitation outcomes in patients can be applied directly to optimizing rehabilitation programs. Although muscle hypertrophy occurred early during rehabilitation, plantarflexor muscle function (specific torque) should remain the focus of rehabilitation programs because although CSA recovered quickly, specific torque still lagged behind that of control subjects.

Adaptation, Physiological↗
PubMed2004

The biopsy.

The biopsy of a musculoskeletal lesion is an important event, the outcome of which guides patient management and helps determine patient prognosis. The principles of biopsy include complete radiologic staging before the biopsy, thorough prebiopsy planning including consultation with the pathologist and radiologist, determining the most appropriate method of biopsy (fine needle, core needle, open surgical biopsy), placing the biopsy tract appropriately, and making sure the biopsy tract can be removed at the time of resection, avoiding contamination of uninvolved structures, avoiding transverse incisions, preventing pathologic fracture, handling biopsy tissue appropriately, and considering referral before biopsy. The common errors of biopsy include sampling errors, postbiopsy hematomas, the use of transverse incisions, tumor implantation, and the treatment of an unsuspected sarcoma with prophylactic fixation. Thoughtful prebiopsy planning and careful completion of the biopsy can result in an expedient and accurate diagnosis. If the treating physician lacks significant expertise in performing biopsy and management of patients with musculoskeletal lesions, then referral to a musculoskeletal oncologist before biopsy should be considered.

Biopsy↗
PubMed2003

Radiation therapy for giant cell tumors of bone.

For giant cell tumors of bone, does radiotherapy provide a safe and effective treatment? This retrospective review includes 24 patients with 26 histologically diagnosed tumors treated with megavoltage radiotherapy between March 1972 and July 1996. Of the 10 recurrent tumors, five had an intralesional resection, two had a biopsy, and three had no biopsy before radiotherapy. Of the 16 previously untreated tumors, one was irradiated after a marginal resection, five after an intracapsular resection, and 10 after biopsy alone. The total doses ranged from 35 to 55 Gy (median, 43 Gy) in fractions of 1.67 to 2.33 Gy per day. Twenty of 26 tumors (77%) were controlled locally. All of the local recurrences occurred within the irradiated field. Five of six patients with local recurrence were treated successfully with additional surgery. Salvage surgery after local recurrence required amputation of an extremity in three patients and a total knee replacement in one patient. The ultimate local control rate was 96% with one patient alive with progressive disease. Lung metastases in one patient were treated successfully with surgery, chemotherapy, and radiotherapy. In one patient a radiation-induced sarcoma developed 22 years after treatment. The authors conclude that radiation therapy is a safe and effective treatment option for benign giant cell tumors of bone. A total dose greater than 40 Gy is the only variable found to significantly influence local control.

Adolescent↗
PubMed2003

Grade 2 chondrosarcoma: stage I or stage II tumor?

We analyzed chondrosarcomas of bone to assess whether Grade 2 tumors are more appropriately grouped with Grade 1 chondrosarcomas or Grade 3 and dedifferentiated chondrosarcomas (Musculoskeletal Tumor Society Stage I or Stage II). A retrospective chart review identified 109 patients who presented with nonmetastatic chondrosarcoma. Data were gathered on each tumor's histologic grade, extent (intracompartmental versus extracompartmental), resection margin status, and site (axial versus appendicular). The cohort included 60 males and 49 females with a mean age of 50 years. Forty tumors were located in the axial skeleton and the remainder were distributed throughout the appendicular skeleton. Fifty-three tumors were Grade 1, 40 tumors were Grade 2, eight tumors were Grade 3, and eight tumors were dedifferentiated. Statistical analysis established grade as the only significant variable for this group of patients; extracompartmental tumor spread also correlated with outcome, but not independent of the grade. Margin status and site were not statistically significant with respect to outcome. Chi-square analysis also established that Grade 2 tumors are grouped more appropriately with the Grade 1 chondrosarcomas as Musculoskeletal Tumor Society Stage I neoplasms. These data should be considered when developing the surgical plan, particularly for patients with Grade 2 appendicular chondrosarcomas.

Adolescent↗