A 77-year-old man presents to your office with a one-month history of atraumatic left thigh pain. The patient has been followed by a local oncologist who diagnosed him with multiple myeloma two years ago. He has known metastatic lesions throughout his spine. Recent radiographs and magnetic resonance imaging (MRI) confirm the source of the patient’s thigh pain is an impending fracture from a metastatic lesion. The patient’s life expectancy is greater than six months. What is the best next step in treatment of this patient’s impending fracture?
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The patient has a metastatic lesion with multiple myeloma as the known primary source. Radiographic and MRI findings are consistent with a metastatic lesion in the femoral shaft. The lesion involves more than 80% of the lateral cortex, and the associated pain is interfering with the patient’s ability to ambulate. Intramedullary fixation is recommended to stabilize the femur for ambulation and to improve his quality of life.
In general, impending fractures of the lower extremity in patients with a life expectancy greater than 6 to 12 weeks should be stabilized with surgical fixation. However, not all pathologic lesions should be treated operatively with surgical stabilization. Surgery is reserved for patients at high risk for fracture in order to prevent comorbidities associated with a sudden fracture. Surgical stabilization prior to fracture prevents soft tissue injury, which improves postoperative rehabilitation.
Predicting fracture risk helps determine if surgical fixation is necessary in an elective setting. The most widely used rating system to predict pathologic fractures is the Mirels’ rating system, which uses a scoring system based on four tumor characteristics to help guide treatment. The four characteristics include site of the lesion, nature of the lesion, size of the lesion, and pain. Each characteristic is broken into three categories and assigned a score for each. The tumor characteristic, categories, and corresponding scores are as follows: site of lesion (upper extremity , lower extremity , peritrochanteric ), nature of lesion (blastic , mixed , lytic ), size of the lesion expressed as a fraction of cortical thickness (less than one-third , one-third to two-thirds , more than two-thirds , and pain (mild , moderate , functional ). Prophylactic intramedullary fixation is recommended for a lesion with an overall score of more than 9 and should be considered for a lesion with a score of 8. A lesion with an overall score of 7 or less can be treated noninvasively with radiation and chemotherapy. Surgical decision making is ultimately up to the treating orthopedic surgeon and may also be influenced by patient size and activity level.
This patient has a lesion in the lower extremity (scores 2), a lytic lesion on radiographic examination (scores 3), more than 2/3 cortical disruption of the lateral cortex (scores 3), and functional pain (scores 3). Overall the patient has a Mirels’ rating score of 11, which would recommend prophylactic intramedullary nailing.
- Jawad MU, Scully SP. In brief: classifications in brief: Mirel’s classification: metastatic disease in long bones and impending pathologic fractures. Clin Orthop Relat Res. 2010;468 (10):2825-2827.
- Quinn RW, Randall RL, Benvenia J, Berven SH, Raskin KA. Contemporary management of metastatic bone disease: tips and tools of the trade for general practitioners. J Bone Joint Surg Am. 2013;95(20):1887-1895.