Metastatic Carcinoma Clinical Presentation

Although pain is an important symptom of musculoskeletal metastases, it is nonspecific. The pain pattern can be helpful if, in addition to being activity-related, it is present at rest and at night, especially in patients older than 50 years. However, this pain pattern can be present in patients with osteomyelitis and Paget disease, and in these instances, it is also is nonspecific.

Diagnostic factors

An orthopedic surgeon will be consulted in the following instances to help evaluate a patient with a suspicious bony defect.

• In the first instance, the surgeon is asked to help evaluate a patient a patient who has experienced a pathologic fracture or who has a known primary carcinoma as well as a bony defect.
• In the second, more worrisome instance, the surgeon is consulted in the evaluation of a patient whose bony defect was serendipitously found during the radiologic evaluation of another condition.

In the above instances, the orthopedist must perform 3 functions:

• Determine the cause of the bony defect.

  • In a limited number of patients, bony defects are often found serendipitously during radiographic evaluation of the affected part for other reasons. In these instances, the orthopedist is asked to determine if the discovered bony defect is a benign event requiring no further management or one that needs further investigation. The following are examples of such defects.
    • The stippled, calcific, benign-appearing enchondroma found in the proximal humerus during an evaluation of a patient for a rotator cuff tear
    • Bony physiologic changes in the intertrochanteric area of the proximal femur, which may be found on plain anteroposterior (AP) pelvic radiographs during evaluation of the pelvis for other reasons
    • An area of fibrous dysplasia, which may be observed on radiographs that have been taken of a patient involved in some traumatic event
  • It is often difficult to determine whether a bony defect found during a bone survey for metastatic disease is the result of that disease or of some other condition. For instance, a benign bone island, an area of osteopoikilosis or fibrous dysplasia, can produce a similar radiographic appearance. A bone biopsy is often required to determine the actual diagnosis of such a defect. If the patient has already been diagnosed as having a primary tumor, the management of the recently discovered bony defect is relatively uncomplicated.
  • When the diagnosis of the bony defect needs to be proven for therapeutic reasons, biopsy is appropriate. For example, the radiotherapist or oncologist may need confirmation that the recently discovered bony defect is the same as the primary tumor or that the bony site results from another condition. Bone biopsies can be accomplished in a number of ways, but for the diagnosis of bony metastases, the most appropriate and least invasive method for making a diagnosis is needle biopsy.
• Predict the probability of fracture.^[12]

  • If the biopsy confirms that the bony defect has been caused by metastatic disease, the orthopedist must then decide if the defect fits the criteria for an impending fracture. The definition of an impending fracture is the presence of a bony defect that is likely to result in a pathologic fracture with physiologic loading (ie, activities of daily living). In this case, the orthopedist should determine the probability of fracture by examining plain radiographic findings and by conducting an interview with the patient. Quantitating the risk of fracture based on plain radiography alone is very subjective because the broad guidelines in the literature are based on small numbers of patients and, therefore, are limited in value. Using them can result in errors of judgment more than 50% of the time.
  • According to a 1995 report by Hipp and colleagues, useful criteria are as follows: defect geometry affecting load-bearing capacity, the histologic cell causing the defect (ie, blastic, lytic, or mixed), and the anatomic site (femoral neck vs greater trochanter).^[13] For instance, according to the study, the factor of risk for fracture of a normal proximal femur is approximately 0.4. The thinnest part of a cortical wall is the critical factor for predicting loss of strength. Central lesions with a 50% symmetrical loss of bone produce a 60% loss of bending strength. In patients who have eccentric bone loss, a 50% bone mass reduction results in a 90% reduction of bending strength. Therefore, a lesion located in areas that increase the risk factors to the bone must be considered.
  • Length of a bony lesion has been reported as critical only in torsional loads. The load-bearing capacity of bone apparently depends on: 1) the location of the defect with respect to the applied load, 2) the type of applied load, 3) the amount of bone loss, and 4) the condition of the remaining bone. The anatomic location of a bony lesion also is important. As the literature has shown, a drill hole that has been placed inappropriately in the lateral femoral shaft (at or below the level of the lesser trochanter) for fixation of a nonneoplastic femoral neck fracture results in a high risk of bone fracture with weight bearing through the lateral femoral cortical drill hold defect. Therefore, a similarly sized metastatic lesion in this area can be expected to create a similarly high fracture risk.
• Prophylactically fix a pathologic or impending fracture.

  • When a bony site displays radiographic and clinical evidence of an impending or already completed pathologic fracture, surgical stabilization is indicated. Most current literature supports the prophylactic fixation of impending fractures to minimize morbidity and protect function. In contrast, waiting for an impending fracture to occur increases morbidity and mortality and affects the patient's ability to regain function in as short a time as possible.
  • Because the life span of these patients is limited, the goal of management needs to be centered on returning as much function as possible as rapidly as possible.