High Yield Topics

Pathologic Fractures

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Ovid: Handbook of Fractures

Authors: Koval, Kenneth J.; Zuckerman, Joseph D.
Title: Handbook of Fractures, 3rd Edition
> Table of Contents > I – General Considerations > 5 – Pathologic Fractures

5
Pathologic Fractures
DEFINITION
  • A pathologic fracture is one that occurs
    when the normal integrity and strength of bone have been compromised by
    invasive disease or destructive processes.
  • Causes include neoplasm, necrosis,
    metabolic disease, disuse, infection, metastatic disease, osteoporosis,
    iatrogenic causes (e.g., surgical defect), or primary bone tumor.
  • Fractures more common in benign tumors (versus malignant tumors).
    • Most are asymptomatic before fracture.
    • Antecedent nocturnal symptoms are rare.
    • Most common in children:
      • Humerus
      • Femur
      • Unicameral bone cyst, fibroxanthoma, fibrous dysplasia, eosinophilic granuloma
  • Primary malignant tumors
    • These are relatively rare.
    • Osteosarcoma, Ewing sarcoma, malignant fibrous histiocytoma, fibrosarcoma are examples.
    • They may occur later in patients with radiation osteonecrosis (Ewing sarcoma, lymphoma).
    • Suspect a primary tumor in younger patients with aggressive-appearing lesions:
      • Poorly defined margins (wide zone of transition)
      • Matrix production
      • Periosteal reaction
    • Patients usually have antecedent pain before fracture, especially night pain.
    • Pathologic fracture complicates but does not mitigate against limb salvage.
    • Local recurrence is higher.
    • Survival is not compromised.
  • Patients with fractures and underlying suspicious lesions or history should be referred for biopsy.
  • Always obtain a biopsy of solitary destructive bone lesions even in patients with a history of primary carcinoma.
MECHANISM OF INJURY
  • Pathologic fractures may occur as a result of minimal trauma or even during normal activities.
  • Alternatively, pathologic fractures may occur during high-energy trauma involving a region that is predisposed to fracture.
CLINICAL EVALUATION
  • History: Suspicion of pathologic fracture should be raised in patients presenting with fracture involving:
    • Normal activity or minimal trauma.

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    • Excessive pain at the site of fracture prior to injury.
    • Patients with a known primary malignant disease or metabolic disease.
    • A history of multiple fractures.
    • Risk factors such as smoking or environmental exposure to carcinogens.
  • Physical examination: In addition to the
    standard physical examination performed for the specific fracture
    encountered, attention should be directed to evaluation of a possible
    soft tissue mass at fracture site or evidence of primary disease such
    as lymphadenopathy, thyroid nodules, breast masses, prostate nodules,
    rectal lesions, as well as examination of other painful regions to rule
    out impending fractures.
Table 5.1. Disorders producing osteopenia
  Laboratory Value
Disorder Serum Calcium Serum Phosphorus Serum Alkaline Phosphatase Urine
Osteoporosis Normal Normal Normal Normal Ca
Osteomalacia Normal Normal Normal Low Ca
Hyperparathyroidism Normal to high Normal to low Normal High Ca
Renal osteodystrophy Low High High  
Paget disease Normal Normal Very high Hydroxyproline
Myelomaa Normal Normal Normal Protein
aAbnormal serum or urine immunoelectrophoresis.
From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.

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LABORATORY EVALUATION (T 5.1)
  • Complete blood cell count (CBC) with differential, red blood cell indices, and peripheral smear
  • Erythrocyte sedimentation rate (ESR)
  • Chemistry panel: electrolytes, with calcium, phosphate, albumin, globulin, alkaline phosphatase
  • Acid phosphatase in male patients with an unknown primary tumor
  • Urinalysis
  • Stool guaiac
  • Serum and urine protein electrophoresis (SPEP, UPEP) to rule out possible myeloma
  • 24-hour urine hydroxyproline to rule out Paget disease
  • Specific tests: thyroid function tests
    (TFTs), carcinoembryonic antigen (CEA), parathyroid hormone (PTH),
    prostate specific antigen (PSA)
RADIOGRAPHIC EVALUATION
  • Plain radiographs: As with all fractures,
    include the joint above and below the fracture. It is difficult to
    measure size accurately, particularly with permeative lesions; >30%
    of bone must be lost before it is detectable by plain radiography.
  • Chest radiograph: To rule out primary lung tumor or metastases in all cases.
  • Bone scan: This is the most sensitive
    indicator of skeletal disease. It gives information on the presence of
    multiple lesions, correlates “hot” areas with plain x-rays, and may be
    “cold” with myeloma.
  • Other useful tests in evaluating a patient with suspected pathologic fracture of unknown origin include the following (Table 5.2):
    Table 5.2. Search for primary source in patient with suspected metastatic bone lesion
    1. History, especially of thyroid, breast, or prostate nodule
    2. Review of systems, especially gastrointestinal symptoms, weight loss, flank pain, hematuria
    3. Physical examination, especially lymph nodes, thyroid, breast, abdomen, prostate, testicles, and rectum
    4. Radiographs: chest, kidneys-ureters-bladder, humeri, pelvis, femora
    5. Total-body technetium-99m bone scan
    6. Abdominal ultrasound
    7. Laboratory: complete blood count, erythrocyte sedimentation rate,
      calcium, phosphate, urinalysis, prostate-specific antigen,
      immunoelectrophoresis, and alkaline phosphatase
    8. Biopsy: frozen section before prophylactic fixation
    From Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 5th ed. Baltimore: Lippincott Williams & Wilkins, 2002:561.
    • Upper/lower gastrointestinal series
    • Endoscopy
    • Mammography
    • Computed tomography of the chest, head, and abdomen
    • Liver, spleen, thyroid scans
    • Intravenous pyelogram, renal ultrasound
Despite an elaborate workup, including all the tests
outlined here, the primary disease process will not be identified in
15% of patients with suspected metastatic disease.
CLASSIFICATION
Springfield
This is based on the pattern of bone invasion.
Systemic
  • Osteoporosis: This is the most common cause of pathologic fractures in the elderly population.

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  • Metabolic bone disease: Osteomalacia and hyperparathyroidism may be present.
  • Paget disease: This is present in 5% to
    15% of the elderly population. Pathologic fracture is the most common
    orthopaedic complication, seen in 10% to 30% of patients and often the
    first manifestation of unrecognized Paget disease.
Localized
  • This accounts for the majority of pathologic fractures and includes:
    • Primary malignancy of bone.
    • Hematopoietic disorders: myeloma, lymphoma, leukemia.
    • Metastatic disease:
      • Most pathologic fractures (80%) from metastatic disease arise from lesions of the breast, lung, thyroid, kidney, prostate.
      • Most common locations include the spine, ribs, pelvis, femur, humerus.
Classification by Pathologic Process
Systemic Skeletal Disease
  • Bones are weak and predisposed to fracture. Healing and callus formation are normal.
  • Correctable disorders include
    osteomalacia, disuse osteoporosis, hyperparathyroidism, renal
    osteodystrophy, and steroid-induced osteoporosis.
  • Noncorrectable disorders include
    osteogenesis imperfecta, polyostotic fibrous dysplasia, osteopetrosis,
    postmenopausal osteoporosis, Paget disease, rheumatoid arthritis, and
    Gaucher disease.
Local Disease
  • Nonossifying fibroma, unicameral bone
    cyst, aneurysmal bone cyst, enchondroma, chondromyxoid fibroma; giant
    cell tumor, osteoblastoma, chondroblastoma
  • Malignant primary bone tumors
  • Ewing sarcoma, multiple myeloma,
    non-Hodgkin lymphoma, osteosarcoma, chondrosarcoma, fibrosarcoma,
    malignant fibrous histiocytoma
  • Carcinoma metastasized to bone
Miscellaneous
  • Irradiated bone
  • Congenital pseudarthrosis
  • Localized structural defects
TREATMENT
Initial Treatment
  • Standard fracture care: reduction and immobilization
  • Evaluation of underlying pathologic process
  • Optimization of medical condition

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Nonoperative Treatment
  • In general, fractures through primary benign lesions of bone will heal without surgical management.
  • Healing time is slower than in normal bone, particularly after radiation therapy and chemotherapy.
  • Contrary to popular belief, the fracture will not stimulate involution of the lesion.
Operative Treatment
  • Goals of surgical intervention are:
    • Prevention of disuse osteopenia.
    • Mechanical support for weakened or fractured bone to permit the patient to perform daily activities.
    • Pain relief.
    • Decreased length and cost of hospitalization.
  • Internal fixation, with or without cement
    augmentation, is the standard of care for most pathologic fractures,
    particularly long bones. Internal fixation will eventually fail if the
    bone does not unite.
  • Loss of fixation is the most common complication in the treatment of pathologic fractures, owing to poor bone quality.
  • Contraindications to surgical management of pathologic fractures are:
    • General condition of the patient inadequate to tolerate anesthesia and the surgical procedure.
    • Mental obtundation or decreased level of consciousness that precludes the need for local measures to relieve pain.
    • Life expectancy of <1 month (controversial).
  • Adequate patient management requires
    multidisciplinary care by oncologists, internal medicine physicians,
    and radiation therapists.
    • Radiation and chemotherapy are useful
      adjunctive therapies in the treatment of pathologic fractures, as well
      as potential mainstays of therapy in cases of metastatic disease.
      • These treatments are used to decrease the size of the lesion, stop lesion progression, and alleviate symptoms.
      • They delay soft tissue healing and should not be administered until 10 to 21 days postoperatively.
  • Goals of surgery in treating patients with pathologic fractures are:
    • Pain relief.
    • Restoration of function.
    • Facilitation of nursing care.
  • Pathologic fracture survival
    • Seventy-five percent of patients with a pathologic fracture will be alive after 1 year.
    • The average survival is ~21 months.
  • Pathologic fracture treatment includes:
    • Biopsy, especially for solitary lesions.
    • Nails versus plates versus arthroplasty.
      • Interlocked nails to stabilize the entire bone.
      • Arthroplasty for periarticular fractures, especially around the hip.
    • Cement augmentation, which is often necessary.

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    • Radiation and chemotherapy.
    • Aggressive rehabilitation.
Adjuvant Therapy: Radiation Therapy and Chemotherapy
  • Role in treatment of pathologic fractures:
    • Palliate symptoms.
    • Diminish lesion size.
    • Prevent advancement of lesion.
Metastases of Unknown Origin:
  • Three to 4% of all carcinomas have no known primary site.
  • Ten to 15% of these patients have bone metastases.
Management of Specific Pathologic Fractures
Femur Fractures
  • The proximal femur is involved in >50% of long bone pathologic fractures resulting from high weight-bearing stresses.
  • Pathologic fractures of the femoral neck
    generally do not unite regardless of the degree of displacement; these
    require proximal femoral replacement. If the acetabulum is not
    involved, a hemiarthroplasty may be indicated; however, with acetabular
    involvement, total hip replacement is required.
  • Pathologic femoral shaft fractures may be managed with intramedullary nailing.
  • Indications for prophylactic fixation (Harrington) are:
    • Cortical bone destruction ≥50%.
    • Proximal femoral lesion ≥2.5 cm.
    • Pathologic avulsion of the lesser trochanter.
    • Persistent pain following irradiation.
  • Mirel’s scoring system for prophylactic fixation (Clin Orthop 1989) is useful (Table 5.3).
  • Quantitative computed tomography is a sensitive study to assess the degree of bone destruction.
  • Advantages of prophylactic fixation compared to fixation after fracture occurs are as follows:
    • Decreased morbidity
    • Shorter hospital stay
    • Easier rehabilitation
    • Pain relief
    • Faster and less complicated surgery
    • Decreased surgical blood loss
Table 5.3. Mirel’s criteria for risk of fracture
  Number Assigned
Variable 1 2 3
Site Upper arm Lower extremity Peritrochanteric
Pain Mild Moderate Severe
Lesiona Blastic Mixed Lytic
Size <1/3 diameter of the bone 1/3–2/3 diameter of the bone >2/3 diameter of the bone
Each patient’s situation is
assessed a number (1, 2, or 3) to each aspect of his or her
presentation (site, pain, lesion, and size) and then adding the numbers
to obtain a total number to indicate the patient’s risk for fracture.
Mirel’s data suggest that those patients whose total number is 7 or
less can be observed, but those with a number of 8 or more should have
prophylactic internal fixation.
aBy radiography.
From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.

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Humerus Fractures
  • The humeral shaft is frequently involved with metastatic disease, thus increasing the possibility of humeral shaft fracture.
  • Prophylactic fixation of impending pathologic fractures is not recommended on a routine basis.
  • Operative stabilization of pathologic
    fractures of the humerus may be performed to alleviate pain, to reduce
    the need for nursing care, and to optimize patient independence.

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