The patient's comminuted fracture of the right proximal femur was seen by DR examination after his fall, but the DR examination did not provide effective pathological fracture information due to the overlap of the bone cortex at the broken end of the fracture. A retrospective analysis of the CT examination at that time revealed that the bone cortex of the proximal fracture of the right femur in the 2 o'clock to 8 o'clock directions presented osteolytic changes (Fig. 6). Unfortunately, this did not attract the attention of the doctor at that time, and the fracture was treated with open reduction and internal fixation (ORIF) according to the routine fracture care. Since pathologic fracture was not considered before the surgery, no soft tissue biopsy was performed during the surgery. Moreover, the intramedullary tumor tissue was not scraped when the fracture was fixed, and the surrounding soft tissue was not enlarged. We believe that this operation was successful simply from the perspective of achieving open reduction and internal fixation of the fracture. It can be seen that the position of the plate and screw internal fixation was good and the fracture reduction was satisfactory. The results of the subsequent four examinations showed that the fracture did not heal and the right femur had increased osteolytic destruction, and extensive abnormal osteogenesis in the proximal soft tissue of the right femur was also observed. Four months after the operation, ECT showed an abnormal concentration of radionuclides in the proximal segment of the right femur that was considered metastatic bone cancer. The patient did not undergo a histopathological examination of the proximal femur. ECT is highly sensitive but usually has a low specificity. The sensitivity of 99mTc scintigraphy has been reported to range from 62 to 89%, with a false-positive rate as high as 40%6. However, combined with the patient's history, symptoms, CT examination, and joint consultation of oncologists, imaging physicians, orthopedic surgeons, and multidisciplinary physicians, the final diagnosis was bone metastasis. To be very clear, open reduction and internal fixation alone is not appropriate for the treatment of metastatic bone cancer7. Considering the patient's complex medical history and current health status, extensive tumor resection should be performed. The expanded resection should include the extent of bone resection, as the disease will invade the soft tissue around maximum resection margin, obtain a good surgical disease-free boundary, and include right femoral reconstruction with tumor prosthesis; additionally, postoperative radiotherapy should cover the entire area, scope and distal and proximal end of all tumor prostheses. Because pathologic fractures due to metastatic cancer were not considered at the time of surgery, the emergency department missed a very important magnetic resonance imaging (MRI) examination. Therefore, we have no way of knowing the extent of soft tissue invasion of the tumor at the time of the injury, and we have no way of determining the extent to which excision was possible to achieve a tumor-free surgical boundary. Subsequently, due to the lack of standard radiotherapy, we observed gradual local progression of the tumor during the following four months after surgery. However, radical right hip arthrotomy is not recommended because patients with liver, lung, and multiple lymph node metastases have lost the opportunity to undergo radical treatment of the tumor.
Bone metastases are an unfavorable consequence and portend poor survival, with a median survival duration of less than 6 months. However, in all reports, the risk of bone metastasis from colorectal cancer is not high, so it is highly likely to be ignored by clinical orthopedic surgeons. In most patients, bone metastases will subsequently present bony destruction, the main mechanism of which is the release of a variety of cytokines by the tumor to increase the number of mononuclear cells followed by the secretion of RANKL to aggregate osteoclast mononuclear cells, thereby breaking the balance between local bone tissue osteogenesis/broken bone healing and leading to local osteolysis. This bone-dissolving effect not only provides more space and nutrients for the tumor but also causes hypercalcemia, bone pain and other symptoms. Since the stability of local bone is reduced, a low-energy injury may lead to pathological fracture of the bone with the lesion. Pathologic fractures occur in 10-30% of all cancer patients, with proximal parts of the long bones being the most frequent fracture site, and femur fractures accounting for over half of all cases[7,8] However, if a patient has both osteolytic and osteoblastic lesions, or if an individual metastasis has both osteolytic and osteoblastic components, then gastrointestinal cancers and squamous cancers maybe present.
Currently, it is believed that bone metastasis is not a direct cause of death in patients but rather leads to a series of complications caused by pathological fractures that seriously affects patient quality of life and significantly increases mortality. A multidisciplinary approach should be decided by medical oncologists, radiotherapists, pain control teams, intervention radiologists, endocrinologists, orthopedic surgeons and psychologists. Finally, we recorded a pathological fracture caused by bone metastasis of rectal cancer based on the imaging findings. After conventional fracture treatment, a continuous process of bone nonunion and local tumor spread occurred. Due to the extreme rarity of the disease, it is the hope that this case will increase awareness of pathological fractures among traumatic orthopedic surgeons. The combination of a medical history, preoperative ECT examination, local DR examination, CT examination and MRI examination are necessary for a preoperative diagnosis.