Eccentric and concentric torque-velocity relationships during arm flexion and extension

Summary Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad·s^–1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+ 10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects wasr0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque ouptput for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque. These findings are discussed in terms of study design, neural inhibition, activation history, muscle-tendon elasticity, muscle fiber types, muscle architecture, and methodological considerations. The present results illustrate the importance of strength level to explain individual differences in TVC.     

Leg Length and Offset Measures with a Pinless Femoral Reference Array during THA

The bony fixation of reference marker arrays used for computer-assisted navigation during total hip arthroplasty (THA) theoretically involves the risk of fracture, infection, and/or pin loosening. We asked whether intraoperative assessment of leg length (LL) and offset (OS) changes would be accurate using a novel pinless femoral reference system in conjunction with an imageless measurement algorithm based on specific realignment of the relationship between a dynamic femoral and pelvis reference array. LL/OS measurements were recorded during THA in 17 cadaver specimen hips. Preoperatively and postoperatively, specimens were scanned using CT. Linear radiographic LL/OS changes were determined by two investigators using visible fiducial landmarks and image processing software. We found a high correlation of repeated measurements within and between (both 0.95 or greater) the two examiners who did the CT assessments. Pinless LL/OS values showed mean differences less than 1 mm and correlations when compared with CT measurements.     

Two column lesions in the thoracolumbar junction: anterior,posterior or combined approach? A comparative biomechanical in vitro investigation

There are various surgical techniques for the treatment of spinal fractures in the thoracolumbar region. Several implants have been developed for anterior or posterior instrumentation. Optimal treatment of unstable thoracolumbar osseous and ligamentous injuries remains controversial. To compare the stabilizing effects of an antero-lateral, thoracoscopically implantable plate system (macsTL, Aesculap, Germany) with the stability provided by a fixateur interne (SOCON, Aesculap, Germany), this in vitro investigation examined six human bisegmental (T12–L2) spinal units. Specimens were tested intact, and with simulation of osseous lesions in the anterior and ligamentous lesions in the posterior column (combined A/B-fracture). While loaded in the main anatomical planes such as flexion/extension, left and right lateral bending and left and right axial rotation with a bending moment of 7.5 Nm in a special testing jigs, motion analysis was performed. Quantitative interpretation of the stabilizing effect was achieved using a contactless three-dimensional motion analysis system. Each specimen was tested in four different scenarios: the first step measured movements of intact spinal segments. For the second step, specimens underwent simulation of combined A/B-fracture provided with bisegmental (T12/L2) antero-lateral fixation and bone strut graft from the iliac crest. For the third step, segments were additionally stabilized by the fixateur interne. The last measurement (fourth step) was performed after removing the anterior instrumentation. Range of motion (ROM) values were compared and statistically evaluated. Compared to the intact specimens the anterior instrumentation of the combined lesion, simulated A/B-fracture, leads to a stabilizing effect in flexion/extension and lateral bending. In contrast to these findings the torsional instability increased for the upper segment and bisegmentally. A maximum rigidity, beyond intact values, was registered for each anatomical plane with the combined instrumentation: antero-lateral and fixateur interne. After removing the anterior screw plate system maximum movements, in all segments for flexion/extension and lateral bending, bisegmentally and for the upper segment in axial rotation, were less than ROM values measured with the anterior system only. With respect to these findings a combined ventro-dorsal stabilization procedure should be considered for ligamentous disruptions of the posterior column in combination with A-fractures in the thoracolumbar junction.     

Electron and High-Dose-Rate Brachytherapy Boost in the Conservative Treatment of Stage I–II Breast Cancer

BACKGROUND AND AIMS: To evaluate the effect of electron and high-dose-rate brachytherapy (HDR BT) boost on local tumor control (LTC), side effects and cosmesis after breast-conserving surgery (BCS) in a prospective randomized study. PATIENTS AND METHODS: 207 women with stage I-II breast cancer who underwent BCS were treated by 50 Gy irradiation to the whole breast and then randomly assigned to receive either a boost to the tumor bed (n = 104) or no further radiotherapy (n = 103). Boost treatments consisted of either 16 Gy electron irradiation (n = 52) or 12-14,25 Gy HDR BT (n = 52). Breast cancer-related events, side effects, and cosmetic results were assessed. RESULTS: At a median follow-up of 5.3 years, the crude rate of local recurrences was 6.7% (7/104) with and 15.5% (16/103) without boost. The 5-year probability of LTC, relapse-free survival (RFS), and cancer-specific survival (CSS) was 92.7% vs. 84.9% (p = 0.049), 76.6% vs. 66.2% (p = 0.044), and 90.4% vs. 82.1% (p = 0.053), respectively. There was no significant difference in LTC between patients treated with electron or HDR BT boost (94.2% vs. 91.4%; p = 0.74). On multivariate analysis, patient age < 40 years (RR: 4.53), positive margin status (RR: 4.17), and high mitotic activity index (RR: 3.60) were found to be significant risk factors for local recurrence. The incidence of grade 2-3 side effects was higher in the boost arm (17.3% vs. 7.8%; p = 0.03). However, the rate of excellent/good cosmetic results was similar for the two arms (85.6% vs 91.3%; p = 0.14). Cosmesis was rated as excellent/good in 88.5% of patients treated with HDR BT and 82.7% of patients with electron boost (p = 0.29). CONCLUSIONS: Boost dose significantly improves LTC and RFS in patients treated with BCS and radiotherapy. In spite of the higher incidence of late side effects in the boost arm, boost dose is strongly recommended for patients at high risk for local recurrence. Positive or close margin status, high mitotic activity index, and young patient age should be viewed as absolute indications for tumor bed boost. LTC and cosmesis are excellent and similar to patients boosted with either HDR BT or electrons.     

Radiotherapy Confined to the Tumor Bed Following Breast Conserving Surgery

BACKGROUND: The standard technique of radiotherapy (RT) after breast conserving surgery (BCS) is to treat the entire breast up to a total dose of 45-50 Gy with or without tumor bed boost. The majority of local recurrences occur in close proximity to the tumor bed. Thus, the necessity of whole breast radiotherapy has been questioned, and several centers have evaluated the feasibility and efficacy of sole tumor bed irradiation. The aim of this study was to review the current status, controversies, and future prospects of tumor bed irradiation alone after breast conserving surgery. MATERIAL AND METHODS: Published prospective trials evaluating the feasibility and efficacy of radiotherapy confined to the tumor bed following breast conserving surgery were reviewed in order to analyze treatment results. RESULTS: In three earlier studies, using tumor bed radiotherapy for unselected patients, the incidence of intra-breast relapse was reported in the range of 15.6-37%. However, in nine prospective phase I-II trials, sole brachytherapy (BT) with different dose rates, strict patient selection, and meticulous quality assurance, resulted in 95.6-100% local control rates. To date, only one phase III protocol has been initiated comparing the efficacy of tumor bed brachytherapy alone with conventional whole breast radiotherapy. The ideal extend of the planning target volume (PTV) for tumor bed radiotherapy alone has not been established yet. In most series, PTV was defined as the excision cavity with generous (1-3 cm) safety margins. Minimal requirement for PTV localization is the use of titanium clips to mark the walls of the excision cavity intraoperatively, but the combination of clip demarcation and three-dimensional (3-D) visual information obtained from cross-sectional images seems to be the best method to determine the target volume. 3-D virtual brachytherapy is also a promising method to minimize the chance of geographic miss. Recently developed techniques, such as intraoperative radiotherapy (IORT), as well as accelerated 3-D conformal external beam radiation therapy (3-D-CRT) were also found to be feasible for tumor bed radiotherapy alone. CONCLUSIONS: In spite of the existing arguments against limiting radiotherapy to the tumor bed after breast conserving surgery, results of phase I-II studies suggest that tumor bed radiotherapy alone might be an appropriate treatment option for selected breast cancer patients. Whole breast radiotherapy remains the standard radiation modality used in the treatment of breast cancer, and brachytherapy as the sole modality should be considered as investigational. Further phase-III trials are suggested to determine the equivalence of sole tumor bed radiotherapy, compared with whole breast radiotherapy. Preliminary results with recently developed techniques (CT-image based conformal brachytherapy, 3-D virtual brachytherapy, IORT, 3-D-CRT) are promising. However, more experience is required to define whether these methods might improve outcome for patients treated with tumor bed radiotherapy alone.     

Electron and High-Dose-Rate Brachytherapy Boost in the Conservative Treatment of Stage I-II Breast Cancer First Results of the Randomized Budapest Boost Trial

Background and Aims: To evaluate the effect of electron and high-dose-rate brachytherapy (HDR BT) boost on local tumor control (LTC), side effects and cosmesis after breast-conserving surgery (BCS) in a prospective randomized study. Patients and Methods: 207 women with stage I-II breast cancer who underwent BCS were treated by 50 Gy irradiation to the whole breast and then randomly assigned to receive either a boost to the tumor bed (n = 104) or no further radiotherapy (n = 103). Boost treatments consisted of either 16 Gy electron irradiation (n = 52) or 12-14,25 Gy HDR BT (n = 52). Breast cancer-related events, side effects, and cosmetic results were assessed. Results: At a median follow-up of 5.3 years, the crude rate of local recurrences was 6.7% (7/104) with and 15.5% (16/103) without boost. The 5-year probability of LTC, relapse-free survival (RFS), and cancer-specific survival (CSS) was 92.7% vs. 84.9% (p = 0.049), 76.6% vs. 66.2% (p = 0.044), and 90.4% vs. 82.1% (p = 0.053), respectively. There was no significant difference in LTC between patients treated with electron or HDR BT boost (94.2% vs. 91.4%; p = 0.74). On multivariate analysis, patient age < 40 years (RR: 4.53), positive margin status (RR: 4.17), and high mitotic activity index (RR: 3.60) were found to be significant risk factors for local recurrence. The incidence of grade 2-3 side effects was higher in the boost arm (17.3% vs. 7.8%; p = 0.03). However, the rate of excellent/good cosmetic results was similar for the two arms (85.6% vs 91.3%; p = 0.14). Cosmesis was rated as excellent/good in 88.5% of patients treated with HDR BT and 82.7% of patients with electron boost (p = 0.29). Conclusions: Boost dose significantly improves LTC and RFS in patients treated with BCS and radiotherapy. In spite of the higher incidence of late side effects in the boost arm, boost dose is strongly recommended for patients at high risk for local recurrence. Positive or close margin status, high mitotic activity index, and young patient age should be viewed as absolute indications for tumor bed boost. LTC and cosmesis are excellent and similar to patients boosted with either HDR BT or electrons. Hintergrund und Ziel: In einer prospektiv randomisierten Studie werden die Effekte eines Elektronenboosts und eines High-Dose-Rate-Brachytherapie-(HDR-BT-)Boosts bezüglich lokaler Tumorkontrolle (LTC), Nebenwirkungen und kosmetischer Ergebnisse nach brusterhaltender Operation (BCS) evaluiert. Patienten und Methodik: 207 Patientinnen mit Brustkarzinomen im Stadium I-II wurden einer BCS zugeführt. Postoperativ erfolgte eine perkutane Radiatio der gesamten Brust bis 50 Gy. Daran schloss sich willkürlich entweder eine Boostbestrahlung des Tumorbetts (n = 104) oder keine weitere Radiatio (n = 103) an. Die Boostbestrahlung erfolgte perkutan mit 16 Gy Elektronen (n = 52) oder in Form einer HDR-BT mit 12-14,25 By (n = 52). Untersucht wurden LTC, Nebenwirkungen und kosmetische Ergebnisse. Ergebnisse: Die mediane Nachbeobachtungszeit betrug 5,3 Jahre. Die Lokalrezidivrate lag mit Boostbestrahlung bei 6,7% (7/104), ohne Boost bei 15,5% (16/103). Die 5-Jahres-Überlebensrate für LTC, für die rezidivfreie Überlebenszeit (RFS) und für die krebsspezifische Überlebenszeit (CSS) betrugen 92,7% vs. 84,9% (p = 0,049), 76,6% vs. 66,2% (p = 0,044) und 90,4% vs. 82,1% (p = 0,053). Bezüglich der LTC bestand kein signifikanter Unterschied zwischen Patienten, die mit einem Elektronen- oder HDR-BT-Boost behandelt wurden (94,2% vs. 91,4$; p = 0,74). Die multivariate Analyse zeigte, dass Faktoren wie Patientenalter > 40 Jahre (RR: 4,53), positive Resektionsränder (RR: 4,17) und ein hoher Mitoseaktivitätsindex (RR: 3.60) das Risiko eines lokalen Rezidivs signifikant erhöhen. Die Inzidenz von Nebenwirkungen Grad 2-3 war im Boost-Arm höher (17,3% vs. 7,8%; p = 0,03). Allerdings waren die sehr guten kosmetischen Ergebnisse in beiden Armen gleich (85,6% bs. 91,3%, p = 0,14). Sehr gute kosmetische Ergebnisse wurden bei 88,5% der Patientinnen mit HDR-BT-Boost und 82,7% der Patientinnen mit Elektronenboost erreicht (p = 0,29). Schlussfolgerungen: Die Boost-Dosis verbessert signifikant LTC und RFS bei Patientinnen, die einer BCS und anschließender Radiatio zugeführt wurden. Obwohl eine höhere Inzidenz an Spätnebenwirkungen im Boost-Arm gefunden wurde, wird eine Boost-Dosis für Patientinnen mit hohem Risiko für die Entwicklung eines Lokalrezidivs empfohlen. Unserer Meinung nach ist bei Faktoren wie positive Schnittränder, schmaler Sicherheitssaum, hoher Mitoseaktivitätsindex und niedriges Patientenalter, die absolute Indikation zur Boost-Bestrahlung des Tumorbetts gegeben. LTC und die kosmetischen Ergebnisse sind sehr gut und unterscheiden sich nicht in Bezug auf Elektronenboost oder HDR-BT-Boost.