What are the important differences that distinguish the management of a cancer-related pathologic fracture from the treatment of ordinary fractures?


Description

The differing approaches to management of cancer-related pathologic fracture and ordinary fracture are based upon the difference in tissue composition between native bone and metastatic lesions. Metastatic lesions are, of course, not made of normal bone tissue and therefore are at risk for a so-called pathological fracture.

 

A pathological fracture is one in which breaks in the bone were caused by an underlying disease, examples of which include cancer (see Figure 1), osteoporosis, or other bone diseases.

Figure 1: Pathological fracture of the humerus in a patient with metastasis of renal cell carcinoma, from Wikipedia

 

Typically, skeletal metastases are derived from carcinomas and are osteolytic: the tumor cells in the bone increase osteoclast activity, eroding the bone and causing pain, fractures, and hypercalcemia. Lesions can also be osteoblastic and are characterized by increased bone formation (as seen with metastases from prostate cancer) or mixed osteoblastic and osteolytic. These lesions lead to abnormal bone architecture that is prone to fracture, even in osteoblastic lesions.

 

Treatment and Management

Treatment of an impending or established pathologic fracture draws on many of the techniques that have been developed for the treatment of ordinary fractures in normal bone; yet, there are important differences that distinguish the management of a cancer-related pathologic fracture from the treatment of ordinary fractures, including the following:

  1. Patients with a very short life expectancy may prefer not to have their fractures treated beyond palliative care.

  2. Patients with pathologic fractures may need a more extensive diagnostic work up, including bone scans to exclude additional lesions and possibly a tissue biopsy to confirm the diagnosis. It is possible that a patient might have a new, second cancer (especially if there is a lone "solitary" lesion in the bone).
    • It is especially disastrous to fix one lesion with a plate or rod that ends right above a new lesion. (There are at least three reasons this is very, very bad. Try to deduce them.)

  3. Patients with metastatic disease will frequently be on chemotherapy protocols for their primary diagnosis; if so, timing of any surgical procedures should consider the effect of chemotherapy on marrow suppression and effects on wound healing and immunosuppression. Ideally, surgery would be deferred until blood counts have rebounded.

  4. The timing of surgery and the care needed before must be coordinated with medical and radiation oncologists, among other providers.  

    The patient might need preoperative chemotherapy, radiation or tumor embolization (metastatic renal cell carcinoma, for example, is notorious for its tremendous vascularity, and without preoperative embolization, surgery is especially difficult and dangerous).

    Post-operatively, radiation might be needed to prevent local recurrence) Thus, the treatment should be expeditious but not hasty.


    (Interestingly, the Latin root of "expeditious" is expedire, meaning "to free the feet." In the sense that fixing a femur or tibia fracture in advance will "free" the limb from future problems, such treatment is truly "expeditious!" Indeed, that was the initial meaning of the word: expeditious action would help people extricate themselves (and free their feet) from difficult situations.

  5. Normal bone healing processes are largely absent, and metastatic tissue might be interposed between the ends of the fractured bone. "Minimally invasive techniques" might be inappropriate in these scenarios, especially to the extent that they may make it hard to clear the fracture site and identify cortical gaps. Most pathologic fractures will never heal, so there is no role for bone grafts or other biologic agents; rather, all gaps should be filled with a generous application of bone cement to provide cortical continuity.

  6. Although it is usually beneficial to offer a conservative approach, recognizing that more surgery may be needed (e.g., attempt to fix a fracture with low odds of healing and not choosing prosthetic replacement as the initial operation), patients with pathologic fractures might benefit from more definitive, albeit larger, surgeries initially. Dr Richard D Lackman, a noted orthopaedic oncologist counsels, "It is often preferable to do the last operation first."

  7. It may make sense to fix an impending fracture before an actual break in the bone happens. Large and painful cortical lesions in the leg (especially near the hip) are at high risk of breaking, and surgery performed while the bone is still in continuity is much easier for both the patient and surgeon alike (see Figure 2).
Figure 2: an impeding fracture of the humerus is shown in the image to the left (arrow). This was prophylactically fixed with a locked nail, as shown to the right. (Courtesy of  Treatment of Pathological Humerus-Shaft Tumoral Fractures with Rigid Static Interlocking Intramedullary Nail-22 Years of Experience. Rev. bras. ortop. [online]. 2019, vol.54, n.2  https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-36162019000200149)