Impending pathologic fractures from metastatic malignancy: evaluation and management.

Harrington KD

Both lytic and blastic long bone metastases are at risk to develop pathologic fractures in instances where more than 50% of the circumferential cortical bone has been destroyed or where the pain with weight-bearing stresses persists, increases, or recurs despite adequate local irradiation. Moreover, those most commonly encountered lesions of the proximal femur are at high risk to fracture if they are in excess of 2.5 cm in any dimension or if they are associated with avulsion of the lesser trochanter. Such lesions should be treated aggressively by prophylactic internal fixation. This will avoid the development of a secondary fracture with its concomitantly high risk that true bony healing will not occur even with adequate fixation. When internal fixation is chosen for a large metastasis with extensive cortical destruction, that fixation should be augmented by debulking of the lesion and by packing it with methylmethacrylate polymerizing in situ. Such an expedient not only improves the efficacy of subsequent radiotherapy but also prevents shortening of the bone with weight bearing while enhancing the torque capacity and sheer resistance inherent in the metal fixation device.

Cancer 1997 Oct 15;80(8 Suppl):1614-27

Orthopedic surgical management of skeletal complications of malignancy.

Harrington KD

Department of Orthopaedic Surgery, University of California, San Francisco, USA.

Coincident with improved overall cancer palliation during the past 2 decades has been an increasing incidence of clinically apparent bone metastases, and from these metastases subsequent pathologic fractures of the long bones, spine, and pelvis. Current techniques for surgical management of these fractures are extremely effective in alleviating pain and allowing patients to resume an ambulatory status, often without the need of external support. This, in turn, has significantly improved the quality of the remaining months or years of these individuals' lives. In fact, the long term survival of patients after their first long bone pathologic fracture from malignancy has more than tripled for the most common cancers (breast carcinoma, prostate carcinoma, lymphomas, and myelomas) during the past 25 years. Surgical techniques for stabilizing pathologic or impending fractures must be individualized for the area of involvement, the particular qualities of the bone involved, and the potential for involvement of adjacent soft tissue structures. Long bone fractures most commonly occur in the femur and humerus and are typically internally fixed by intramedullary devices that control impaction, distraction, and torquing stresses by the use of proximal and distal interlocking fixation. Such fixation must be able to withstand weight-bearing stresses on lower extremity long bones. Upper extremity pathologic fractures are often subjected to distractive forces inherent in lifting and pulling, but they are also subjected to heavy compressive forces, particularly in patients who require crutches or other devices to assist them in walking. Fixation of upper or lower extremity long bone fractures ordinarily may be accomplished with minimal blood loss or morbidity. In contrast, fractures or impending fractures involving the acetabulum necessitate extensive joint reconstruction, with inherent increased potential for morbidity and complications. For this reason, the anticipated prognosis for survival and mobility should be greater preoperatively for patients with acetabular fractures than for patients with fractures of either upper or lower extremity long bones. Most spinal metastases can be managed conservatively. Those requiring surgical intervention present with progressive neurologic compromise, which requires decompression, or spinal instability, which requires stabilization. Constructs for internal stabilization of the spine must not be adversely affected by local postoperative irradiation. Ninety-six percent of patients experience good or excellent relief of pain after internal fixation of pathologic malignant long bone fractures. Eighty-four percent of patients with acetabular fractures experience good or excellent relief of pain after joint reconstruction. Eighty-two percent of patients with neurologic compromise secondary to vertebral malignancy improve at least one functional grade after decompression and stabilization, and 88% experience good or excellent relief of spinal pain with restoration of walking ability. Thirty-two percent survived for more than 2 years after spinal decompression and stabilization. Patients with pathologic fractures from metastatic carcinoma of the breast had a mean survival of 24.6 months after surgical management of their fractures. There was a similarly encouraging improvement in the survival statistics for patients with other primary tumor types. Most malignant pathologic fractures of the pelvis, long bones, or spine are amenable to effective stabilization by the techniques described in this article. These techniques allow resumption of weight-bearing ambulation in all but a few patients, good or excellent relief of pain in the vast majority, and an enhanced anticipation of survival and improvement in quality of life.

Clin Orthop 1995 Mar;(312):120-35

Predicting pathologic fracture risk in the management of metastatic bone defects.

Hipp JA, Springfield DS, Hayes WC

Department of Orthopaedic Surgery, Beth Israel Hospital, Boston, MA 02215, USA.

Guidelines for the prediction of pathologic fracture would facilitate the management of patients with metastatic bone defects. Unfortunately, existing clinical guidelines have not been validated, often run counter to engineering practice, and do not accurately predict the risk of fracture for many patients. To serve as a basis for improved guidelines, a factor of risk for a pathologic fracture is defined as the load applied to a bone divided by the load at which the bone fails. Failure loads for bones with metastatic defects have been measured in vitro, and depend on defect geometry, bone properties, and the type of loading. For a diaphyseal defect that destroys 50% of the cortex, strength reductions of between 60% and 90% can occur. The load-bearing capacity of a long bone with a diaphyseal defect also can be predicted using computer models if the geometry of the defect and properties of surrounding bone are known. Similarly, new methods that apply basic engineering principles to computed tomography data allow prediction of the load-bearing capacity of vertebrae with simulated defects. By contrast, the data presented here suggest that by using plane radiographs or computed tomographic (CT) examinations, experienced orthopaedic surgeons cannot accurately estimate the strength reductions or load-bearing capacity for proximal femurs with intertrochanteric defects. By combining new methods to predict the load-bearing capacity with estimated loads for activities of daily living, it is possible to calculate a factor of risk for pathologic fractures.

Clin Orthop 1989 Dec;(249):256-64

Metastatic disease in long bones. A proposed scoring system for diagnosing impending pathologic fractures.

Mirels H

Department of Orthopaedics, University of the Witwatersrand, Johannesburg, South Africa.

A weighted scoring system is proposed to quantify the risk of sustaining a pathologic fracture through a metastatic lesion in a long bone. This system objectively analyzes and combines four roentgenographic and clinical risk factors into a single score. Retrospective analysis of metastatic long bone lesions was completed in 78 lesions that had been irradiated without prophylactic surgical fixation. Clinical data and roentgenograms were scored prior to irradiation by independent observers. The outcome identified 51 lesions that did not fracture during the subsequent six months and 27 lesions that fractured within six months. A mean score of 7 was found in the nonfracture group, whereas the fracture group had a mean score of 10. The percentage risk of a lesion sustaining a pathologic fracture could be predicted for any given score. As the score increased above 7, so did the percentage risk of fracture. It is suggested that all metastatic lesions in long bones be evaluated prior to irradiation. Lesions with scores of 7 or lower can be safely irradiated without risk of fracture, while lesions with scores of 8 or higher require prophylactic internal fixation prior to irradiation.

Acta Orthop Scand 1981 Dec;52(6):623-7

Incidence of fracture through metastases in long bones.

Fidler M

A knowledge of the incidence of fractures through metastases of various sizes in long bones is important when considering prophylactic internal fixation.  Fractures are highly unlikely to occur (2.3 per cent) when less than 50 per cent of the cortex is destroyed and most likely to occur (80 per cent) when over 75 per cent of the cortex is destroyed.

Acta Orthop Belg 1993;59 Suppl 1:6-11

Evaluation of impending fractures and indications for prophylactic fixation of metastases in long bones. Review of the literature.

Haentjens P, Casteleyn PP, Opdecam P

Dienst Orthopedie & Traumatologie, Akademisch Ziekenhuis VUB, Vrije Universiteit Brussel, Belgium.

Prophylactic surgery is recommended in the following situations: Persisting or increasing local pain despite the completion of radiation therapy; permeative involvement; a solitary well-defined lytic lesion greater than 2.5 cm; a solitary well-defined lytic lesion circumferentially involving more than 50% of the cortex; metastatic involvement of the proximal femur associated with a fracture of the lesser trochanter.

Clin Oncol (R Coll Radiol) 1992 Jul;4(4):244-8

The value of internal fixation and radiotherapy in the management of upper and lower limb bone metastases.

Hardman PD, Robb JE, Kerr GR, Rodger A, MacFarlane A

Department of Clinical Oncology, Western General Hospital, Edinburgh, UK.

Fifty-four consecutive patients underwent 61 orthopaedic operations for metastatic bone disease affecting the upper and lower limbs. These patients were subsequently managed using a consistent postoperative radiotherapy (RT) policy. There were 27 prophylactic internal fixations and 34 internal fixations of pathological fractures. There was a marked difference in survival between these groups. The median postoperative survival of the prophylactic (P) group was 15 months whereas that of the fracture (F) group was 2 months (P less than 0.0001). Ninety-three per cent of the P group and 59% of the F group were able to be discharged home following treatment. Subsequent local fracture requiring further surgical intervention occurred in 11% of the P group and in none of the F group. Seventy-eight per cent of the P group and 62% of the F group did not suffer any further sequelae at the operation site until the time of death or last follow-up. Patient mobility following surgery and RT for metastatic lesions occurring in the lower limb was significantly improved in both the P group (P less than 0.05) and in the F group (P less than 0.0001) such that 91% and 58%, respectively, of these patients were subsequently able to walk.