The periarticular bone is the best site for malignant bone tumors to develop. Limb preservation in children with periarticular malignant tumors is very difficult in bone tumor treatment. The clinical application of neoadjuvant chemotherapy and the continuous development of limb-preserving technology have gradually replaced the traditional amputation of malignant bone tumors by various limb-preserving surgeries, creating conditions for limb-preserving treatment of osteosarcoma [1]. Limb-preserving surgery has become the mainstream method of surgical treatment. How to perform radical tumor resection, limb preservation and functional reconstruction based on regular chemotherapy in the perioperative period in the management of childhood peri-knee malignant tumors is a problem worthy of attention and research [2], and a variety of surgical methods to avoid postoperative limb inequality have been reported abroad in recent years and are beginning to be reported in China. Zhu Keshun, Department of Orthopedics, Air Force General Hospital
From May 2004 to June 2009, we admitted five children with osteosarcoma of the upper tibia and performed hemiarthroplasty after tumor resection with satisfactory postoperative results, as reported below.
I. Clinical data
Our five cases were male, aged 8-12 years old, with a mean age of 10 years old, and the duration of the disease was 2-4 months. The reasons for consultation were two cases of hidden pain in the calf and three cases of limited mass with nocturnal pain. All were in the upper tibial segment. The lesions ranged from 9-11 cm, and all children underwent preoperative puncture biopsy in addition to radiological examination, which was pathologically confirmed as osteosarcoma. The surgical oncology Ennecking stage was IIB or less, and all were pathologically confirmed by preoperative puncture biopsy. After 2 courses of neoadjuvant [3] chemotherapy (methotrexate 8-12 g/m2, adriamycin 60 mg/m2, cisplatin 100 mg/m2 isocyclophosphamide 2 g/m2 and other combinations), the tumors were reexamined with different degrees of local boundary clarification and tumor shrinkage. Then regular 1-2 courses of neoadjuvant chemotherapy. Surgery: wide excision or radical resection of the tumor according to Ennecking stage. The tumor is resected according to the borders shown by MRI after chemotherapy, and the operation must be within healthy tissue. Extensive resection is the removal of 2-5 cm of bone and tissue outside the boundaries of the tumor and its response area, including the major fascia within the soft tissue compartment or the periosteum beyond the intraosseous lesion, and intraoperative histopathological examination of the cut edge to determine whether a safe margin has been reached. Radical resection is the removal of the entire bone of the tumor tissue and its interstitial compartment of the affected muscle. When the tumor invades the femoral artery and N vein that cannot be easily separated, the vessels adhering to the tumor are removed and replaced with vascular grafts if necessary. In four cases, artificial hemi-articular prosthesis was implanted in the upper tibia (custom-made by Chunli Zhengda, special model and origin), and in one case, allogeneic bone composite (allogeneic bone + internal fixation material, Shanxi bone bank, the proximal tibia of the donor relied on bone cement fixed with the rod-like stem of the artificial prosthesis) was transplanted. The preoperative design of the matching prosthesis is based on X-ray, CT or MRI measurements. The prosthesis was slightly longer than the osteotomized segment by 1-2 cm, and the artificial hemiarthroplasty was sutured to the metal ring on the prosthesis with a patellar ligament stop. A medial gastrocnemius flap was transferred to cover the prosthesis and sutured to the reconstructed patellar ligament after stopping to re-establish knee extension. Postoperative brace protection and 2 courses of neoadjuvant chemotherapy were performed. Postoperatively, the affected limb was elevated and wrapped in an elastic bandage with compression. The patient was encouraged to flex and extend the ankle and metatarsophalangeal joints and to perform isometric muscle contraction of the quadriceps. Gradual non-weight-bearing joint activities (under physician’s guidance).
II. Results
All children walked under the protection of braces about 4 weeks after surgery, and the mobility of the knee joint was 170-180° in extension and 90-120° in flexion. 1 case had a localized necrotic skin defect of about 3 cm×2 cm at the anterior edge of the right calf after surgery without purulent discharge. The rest of the cases had no tumor metastasis or recurrence on imaging review, and the affected limbs of the four children were shortened by 2-3 cm compared with the healthy side, and all of them were able to carry out daily school life without surgical correction.
Appendix: Typical cases
Case 1, a male, 10 years old, student, came to the clinic with intermittent pain in the left knee for 4 months, which was significantly aggravated for 1 month. The pain was persistent and dull, obvious at night, with mild swelling and weakness, and the general symptomatic treatment was not effective. On physical examination, the anterior medial aspect of the upper left calf was mildly swollen, and the pressure pain and percussion pain were severe. After admission, he was examined: the left upper tibia had a limited redness and swelling of about 2cm×1cm, and was painful to palpation; plain film and CT showed a limited swelling of the upper left tibia, with partial soft tissue infiltration of tibial bone destruction, and the boundaries were unclear, with a length of about 5cm; MRI showed bone destruction of the upper left tibia and partial incomplete periosteum. After admission, he was diagnosed with osteosarcoma after puncture pathology biopsy. Abdominal ultrasound and CT of liver, bile, spleen, kidney, pancreas, lymph nodes and chest radiograph did not show any abnormality. After admission, two cycles of high-dose neoadjuvant chemotherapy were given. The MRI showed a limited mass of approximately 4 cm in length, and a custom-made prosthesis was designed according to X-ray, CT or MRI measurements. The prosthetic hemiarthroplasty was performed under continuous epidural anesthesia. Intraoperative bone destruction was found 6 cm below the articular surface of the upper left tibia, with cancellous bone and intramedullary tumor invasion and partial periosteal invasion. The soft tissues around the tibia were separated, and the upper middle tibia and some of the surrounding soft tissues were cut off, and the bone was osteotomized about 10 cm below the joint surface of the left tibia. The medial gastrocnemius muscle flap was transferred to cover the prosthesis and sutured to the patellar ligament after stop point reconstruction. The prosthesis was immobilized in plaster after surgery, and the patient was treated with two regular courses of chemotherapy in the second week after surgery. 4 weeks later, the patient walked non-weight-bearing under the protection of a brace, 6 weeks after gradual weight-bearing, and 3 months after full weight-bearing.
III. Discussion
The key to the success of the limb-preserving hand is regular and effective chemotherapy in the perioperative period. And the key of surgical operation is to follow the principle of complete resection of tumor, i.e. to use the best surgical boundary to remove the tumor completely. Therefore, our experience is that (i) the indications for surgery should be strictly controlled, i.e. children with Ennecking stage IIA-IIB oncological surgery and those who respond well to chemotherapy. Since chemotherapy can reduce the surgical border of the tumor, it is clinically proven that extensive resection of the tumor on this basis can also achieve the purpose of local radical treatment, therefore, regular 1-2 courses of chemotherapy should be given before and after surgery. We found that after regular preoperative chemotherapy for sensitive tumors in this study, pathology at the time of surgical resection confirmed extensive necrosis of tumor tissues, and even no tumor cells were seen, indicating the positive role and clear effect of preoperative chemotherapy.
With the improvement of the therapeutic effect of chemotherapeutic drugs, limb-preserving reconstruction techniques for malignant bone tumors in children have gradually been widely emphasized and applied [4] [5].
The main methods of reconstruction are: ① Arthrofusion. The advantage is stability, but the knee joint loses its mobility. (ii) Rotational plication. The advantage is that the growth center and “knee” function are preserved, but the appearance is unsightly and difficult for the child and parents to accept. (iii) Allograft bone grafting. Allogeneic bone hemiarthroplasty is a biological reconstruction, but it does not allow for early weight bearing after surgery and is prone to complications such as non-healing, infection, fracture, and late onset sinus tracts. ④Autogenous bone graft. It is mostly used in children with malignant bone tumors that have not invaded the epiphysis. ⑤ Tumor inactivation and reuse, like allogeneic bone, can have postoperative complications such as non-healing, infection, fracture, and delayed sinus tract. (vi) Artificial prosthesis replacement. The most widely used and most effective method, with the possibility of replacing the above methods [6].
In children, especially in adolescents with unclosed epiphyses, amputation, rotationplasty and extendable prosthesis replacement for limb preservation are mainly used. Amputation and rotationplasty are not easily accepted by parents and the children themselves because of the partial loss of function.
In recent years, adjustable prosthesis and individualized prosthesis are developing rapidly. Its earliest application was in 1976, currently there are: (1) Stanmore type prosthesis, now developed to the fourth generation. In order of development, they are: thread-driven (threaded screw adjustment), ball-bearing (tungsten carbide ball filled in the extension piston), C-ring tube (“C” shaped cavity), and minimally invasive. Another type of KMFTR/HMR system is also a molded prosthesis, which is equivalent to the minimally invasive Stanmore prosthesis. (2) Lengthenable prosthesis with external electromagnetic force. The non-invasive lengthenable prosthesis was invented by the French (Phenix prosthesis) and has been improved several times in the 1990s, and now the trade name has been changed to Repiphysis, which is provided by Wright Medical Technology, Inc. The prosthesis consists of a set of tubular structures containing springs compressed by polyethylene. After surgery, when the affected limb is 0.5 to 1.0 cm shorter than the opposite limb, the affected limb is placed in a pre-adjusted electromagnetic field, in which the special components of the prosthesis are heated to soften the adjacent polyethylene compression springs. When the latter is softened (or even melted), the spring expands and the prosthesis is lengthened. Under x-ray guidance, the prosthesis is lengthened by about 0.5 to 1.0 cm at a time. Early clinical results show a bright future for this non-invasive lengthenable prosthesis. (3) Self-adjusting lengthenable prosthesis (invented by Kotz et al.), in which an isometric bevel gear is driven by the movement of the knee joint in flexion to lengthen the prosthesis by threaded screws. However, these lengthenable prostheses are expensive and difficult to use in China, and they require multiple surgeries after surgery and have a high revision rate.
Our artificial hemiarthroplasty has the following advantages: 1. it does not destroy the lateral epiphysis of the femur and allows the lateral epiphysis to continue to grow, while the selected prosthesis is slightly longer than the osteotomy, reducing the difference in length with the contralateral growing limb after surgery. 2. it can maintain the basic walking function after surgery. 3. relatively low price. Disadvantages:1. After resection of the proximal tibial tumor, it is still not possible to make the reconstructed patellar ligament grow directly into the prosthesis; therefore, the patellar ligament must be fixed to the prosthesis during surgery, and the distal head of the medial gastrocnemius muscle is rotated forward and upward to weave a suture with the patellar ligament, which not only strengthens the reattachment of the patellar ligament, but also serves to cover the anterior tibial prosthesis [7][8].2. After the epiphyseal closure of the child’s bone matures, it needs to be replaced again conventional knee prosthesis. Individual children with rapid postoperative contralateral limb growth require secondary or multiple replacements of the hemiarthroplasty, but this is only seen in younger individuals.