| BackgroundBone tumor is a tumor originating from various kinds of bone tissue. It is about 2% of all tumors. It is divided into tumor like lesion, benign tumor and malignant tumor. In the malignant bone tumor, osteosarcoma is the most common and the biggest threat. Osteosarcoma in children and adolescents, the most common site is the most active of the distal femoral epiphysis growth. Before 1970, osteosarcoma treatment options for simple surgical treatment, long-term survival rate was only 20% to 30%, most patients take the radical amputation surgery, but still no can avoid the occurrence of lung metastasis, 5 years survival rate is still disappointing. Nearly 30 years, with the emergence of new adjuvant chemotherapy, based on surgery, treatment of chemotherapy combined with radiotherapy for multiple program, making osteosarcoma 5 year survival rate reached 60% ~ 70%, at the same time, limb salvage surgery has become the mainstream of osteosarcoma were treated to replace previous amputation.For children, tumor type total knee arthroplasty is the main method to treat this kind of patients in clinic. Research group for many years cultivating applicable to the study of children's tumor knee prosthesis, in the world pioneered the double flexion extension motion hemi knee joint concept, and launched a two generation bipolar hemi knee joint prosthesis products, the joint prosthesis due to the effective protection of the tibiofibular platform of the epiphyseal end, making outgrowth of the limb of the patient development potential to be a certain degree of retention, can effectively improve the symptoms of patients with lower limb length discrepancy, achieved satisfactory curative effect in clinical use. Among them, in the second generation of double flexion femoral stem extension movement part of the design of artificial semi knee joint prosthesis in the research group developed a new cementless femoral stem. This is because 1?children patients with bone active growth and osteogenic cells can more quickly into the femoral stem within the porous coating; 2?children with bone quality is better, there is seldom a osteoporosis and other conditions. At the same time, the non bone cement handle can be more reserved for patients with bone; 3?pediatric patients tend to be lighter, non bone cement handle if press fit insertion appropriate can provide sufficient initial stability. In this study, the first part through experiments in vitro mechanics of new non bone cement handle with the traditional bone cement handle control study and analysis of new non bone cement handle with traditional cemented femoral stem in the initial stability of difference; the second part of the history of our hospital has been double flexion extension motion of artificial semi knee joint replacement in 6 patients with the clinical effect of long-term follow-up, and puts emphasis on observing the curative effect of cementless femoral stem. This study is divided into two parts:Part One:A new cementless femoral stem and cemented femoral stem in the control study of in vitro mechanical experiments. ObjectiveTo explore the design characteristics of the new type of cementless femoral stem, compared with the traditional cemented femoral stem in difference on mechanical properties in vitro. MethodsWe will pick out the sheep femurs divided into two groups, model cementless femoral stems with cemented femoral stem were implanted into two groups of sheep femoral, using special fixture fixed bone and prosthesis at both ends, in biomechanical instruments applied vertical pulling and rotating torsional dynamic load recorded two groups of different type of fixation femoral stem pulling out the displacement and rotation micro data, and statistical analysis. Resultsunder the load of 100 N, 200 N, 300 N, 400 N, 500 N and 600 N axial pull pull, pull out the average value, in non bone cement handle group are 1.7522 ± 0.7743 mm, 3.3723 ± 0.6924 mm, 4.6765 ± 0.7351 mm, 6.44870.6982 mm, 7.8543 ± 0.7265 mm,8.8394±0.6755 mm. The bone cement were 1.3470 ±0.5343 mm, 2.4230 ± 0.5024 mm, 2.8196 ±0.5171 mm, 3.3470 ± 0.4835 mm, 3.9568 ±0.5021 mm, 3.9568 ± 0.5021 mm, Two sets of statistical P < 0.05; when loading 2Nm, 4Nm, 6Nm, 8Nm rotating load, fretting about the average values, in cementless handle group are 0.7400±0.1223?m?1.1358±0.1367?m?1.6825± 0.1426?m?2.0786±0.1302?m;Bone cemented handle group were 1.0231±0.1054?m?1.4596± 0.1188?m?1.8255±0.1152?m?2.2786±0.1034?m.(two sets of statistical P > 0.05). ConclusionThe stability of the new type of non bone cement handle is not as stable as the bone cement handle when loading axial tension load. However, the stability of the new type of non cemented stem is similar to that of bone cement. Taking into account the new fibula cemented femoral stem is used in tumor type prosthesis knee joint and the anti rotation ability is maintained femoral stem the initial stability of the key, and therefore non cemented femoral stem initial stability can be comparable with the cemented femoral stem. Part Two:To explore the design characteristics of cementless fixed femoral components for children and their influence on clinical effects; Methods6 children(1 male and 5 female) who underwent double acting and half knee joint operation at our department were followed up from the September 2010 to April 2013. The average age is 8.5±3.2 years(range from 5 to 11 years old). 5 patients suffer from osteosarcoma. 1 patient suffers from malignant schwannoma. 5 cases were at the right lower end of the femur while 1 cases at the lower end of the left femur. One case had pathological fracture before surgery. We used cementless fixed femoral components as distal femoral prosthesis to perform the double acting and a half knee arthroplasty. Functional evaluation of the affected limb was evaluated by using Enneking evaluation standard to evaluate the injured limbs. Radiographic was used to evaluate the filling rate of marrow cavity, the shift of femoral components prosthesis, the periprosthetic radioactive bright line, stress shielding and osteolysis. We also measured the data of limb shortening deformity with postoperative patients. Results6 patients were followed up for 27 months.There were no infection and fracture in replaced joints. MSTS score was 22.5 points. Postoperative X-ray showed that all patients had a satisfactory femoral filling rate of marrow cavity in both planes and no osteolysis was found around all the prosthesis. ConclusionThe new type of cementless fixed femoral components for children with double acting and artificial half knee joint prosthesis was suitable for biological fixation. It can achieve satisfactory clinical outcomes with good initial stability,rapid bone ingrowth and low stress shielding. |
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