The Healing Process of Intracorporeally and In Situ Devitalized Distal Femur by Microwave in a Dog Model and Its Mechanical Properties In Vitro

Background: Limb-salvage surgery has been well recognized as a standard treatment and alternative to amputation for patients with malignant bone tumors. Various limb-sparing techniques have been developed including tumor prosthesis, allograft, autograft and graft-prosthesis composite. However, each of these methods has short- and long-term disadvantages such as nonunion, mechanical failures and poor limb function. The technique of intracorporeal devitalization of tumor-bearing bone segment in situ by microwave-induced hyperthermia after separating it from surrounding normal tissues with a safe margin is a promising limb-salvage method, which may avoid some shortcomings encountered by the above-mentioned conventional techniques. The purpose of this study is to assess the healing process and revitalization potential of the devitalized bone segment by this method in a dog model. In addition, the immediate effect of microwave on the biomechanical properties of bone tissue was also explored in an in vitro experiment. Methods: We applied the microwave-induced hyperthermia to devitalize the distal femurs of dogs in situ. Using a monopole microwave antenna, we could produce a necrotic bone of nearly 20 mm in length in distal femur. Radiography, bone scintigraphy, microangiography, histology and functional evaluation were performed at 2 weeks and 1, 2, 3, 6, 9 and 12 months postoperatively to assess the healing process. In a biomechanical study, two kinds of bone specimens, 3 and 6 cm in length, were used for compression and three-point bending test respectively immediately after extracorporeall

Basic science of osteoarthritis

Osteoarthritis (OA) is a prevalent, disabling disorder of the joints that affects a large population worldwide and for which there is no definitive cure. This review provides critical insights into the basic knowledge on OA that may lead to innovative end efficient new therapeutic regimens. While degradation of the articular cartilage is the hallmark of OA, with altered interactions between chondrocytes and compounds of the extracellular matrix, the subchondral bone has been also described as a key component of the disease, involving specific pathomechanisms controlling its initiation and progression. The identification of such events (and thus of possible targets for therapy) has been made possible by the availability of a number of animal models that aim at reproducing the human pathology, in particular large models of high tibial osteotomy (HTO). From a therapeutic point of view, mesenchymal stem cells (MSCs) represent a promising option for the treatment of OA and may be used concomitantly with functional substitutes integrating scaffolds and drugs/growth factors in tissue engineering setups. Altogether, these advances in the fundamental and experimental knowledge on OA may allow for the generation of improved, adapted therapeutic regimens to treat human OA.(undefined

Separating More Sources Than Sensors Using Time-Frequency Distributions

This paper deals with the problem of blind source separation of nonstationary signals of which only instantaneous linear signals are observed. Exploiting the effectiveness of time-frequency signal processing for nonstationary signals, a blind source separation approach is considered using the observation spatial time-frequency distributions (STFD). Existing solutions are bound to the situation in which the number of sources being separated is less than the number of available sensors measuring the mixed sources. In this paper, we consider the more general case when we can have more sources than sensors assuming that the former are "separable" in the time-frequency domain. The proposed solution proceeds through 3 main steps: (i) a testing procedure is applied (after whitening the STFD) to first separate the cross-terms from auto-terms; (ii), the sources are then separated in the time-frequency domain (from the autoterms only) using a vector classification approach; and finally (iii), the source signatures are obtained using time-frequency synthesis

Quadriceps muscle reconstruction with free functioning latissimus dorsi muscle flap after oncological resection

The concept of limb salvage led to increased demand for more complex and sophisticated reconstructive options to achieve better functional and cosmetic outcome. Reconstruction of the total or partial loss of quadriceps muscle after soft tissue sarcomas excision with free functioning latissimus dorsi muscle transfer had become more popular in the last years. PATIENTS AND METHODS: Between November 1993 and October 2004, 11 patients with average age 45.5 years underwent excision of quadriceps muscle followed by simultaneous reconstruction with free functioning latissimus dorsi muscle. There were six men and five women. The tumors were high grade in 90.9% of patients and were >10 cm in 81.8% of patients. The tumor extension required the resection of the entire quadriceps in four cases, of three heads in six cases, of only two heads in one case. RESULTS: The average follow up was 69 months. The average time of recovery of the contractile activity of the muscle was 8.3 months after operation. The musculoskeletal tumor society rating score (MTSRS) scored excellent or good in 73% of patients. Three patients (27.3%) died of metastatic disease. Local recurrence occurred in one patient (9.1%). Limb salvage was achieved in all the patients (100%). CONCLUSION: This method of reconstruction is a reliable technique not only to fill the defect resulting from oncological resection but also to provide better function. Microsurgical reconstruction of soft tissue sarcoma helps to expand the indications of limb salvage by allowing better local control and achieving adequate function and coverage

Biological reconstruction after resection of bone tumours around the knee: long-term follow-up

We reviewed 25 patients who had undergone resection of a primary bone sarcoma which extended to within 5 cm of the knee with reconstruction by a combination of a free vascularised fibular graft and a massive allograft bone shell. The distal femur was affected in four patients and the proximal tibia in 21. Their mean age at the time of operation was 19.7 years (5 to 52) and the mean follow-up period 140 months (28 to 213). Three vascularised transfers failed. The mean time to union of the fibula was 5.6 months (3 to 10) and of the allograft 19.6 months (10 to 34). Full weight-bearing was allowed at a mean of 21.4 months (14 to 36). The mean functional score at final follow-up was 27.4 (18 to 30) using a modfied 30-point Musculoskeletal Tumour Society rating system. The overall limb-salvage rate was 88%. The results of our study suggest that the combined use of a vascularised fibular graft and allograft is of value as a limb-salvage procedure for intercalary reconstruction after resection of bone tumours around the knee, especially in skeletally immature patients

Biological reconstruction after resection of bone tumors of the proximal tibia using allograft shell and intramedullary free vascularized fibular graft: long-term results

Reconstruction after excision of bone tumor of the proximal tibia is a challenging issue for the reconstructive surgeon. The combined use of a free fibular flap and allograft can provide a reliable reconstructive option in this location. This article describes the authors' long-term follow-up using this technique. Twenty-seven patients that had resection of proximal tibia bone tumors underwent reconstruction using this technique. Only 21 patients that had primary reconstruction were included in this study. All patients had their surgeries performed at least 24 months before the end of the study. The average age at time of operation was 18.1 years. The average follow-up time was 139.3 months. Limb salvage was 82.7%. The average length of the resected tibial segment was 15.3 cm and that of the residual proximal tibia remaining after resection was 2.7 cm. The average time of union of fibula was 5.4 months and for union of allograft was 19.1 months. Primary union of the allograft was achieved in 90.5% of cases. Full weight-bearing was achieved at an average of 21.6 months. Ten patients (47.6%) had 14 local complications. The (MTSRS) average score at final follow-up was 27.3. Local recurrences occurred in two patients (9.5%). Distant metastasis to the lung occurred in three patients (14.3%). One patient died of disease. This technique provides good long-term results in reconstruction of proximal tibia. The viability of the fibula is a cornerstone in both success of reconstruction as well as successful management of complications

Quadriceps muscle reconstruction with free functioning latissimus dorsi muscle flap

NTRODUCTION: The concept of limb salvage led to increased demand for more complex and sophisticated reconstructive options to achieve better functional and cosmetic outcome. Reconstruction of the total or partial loss of quadriceps muscle after soft tissue sarcomas excision with free functioning latissimus dorsi muscle transfer had become more popular in the last years. PATIENTS AND METHODS: Between November 1993 and October 2004, 11 patients with average age 45.5 years underwent excision of quadriceps muscle followed by simultaneous reconstruction with free functioning latissimus dorsi muscle. There were six men and five women. The tumors were high grade in 90.9% of patients and were >10 cm in 81.8% of patients. The tumor extension required the resection of the entire quadriceps in four cases, of three heads in six cases, of only two heads in one case. RESULTS: The average follow up was 69 months. The average time of recovery of the contractile activity of the muscle was 8.3 months after operation. The musculoskeletal tumor society rating score (MTSRS) scored excellent or good in 73% of patients. Three patients (27.3%) died of metastatic disease. Local recurrence occurred in one patient (9.1%). Limb salvage was achieved in all the patients (100%). CONCLUSION: This method of reconstruction is a reliable technique not only to fill the defect resulting from oncological resection but also to provide better function. Microsurgical reconstruction of soft tissue sarcoma helps to expand the indications of limb salvage by allowing better local control and achieving adequate function and coverage