High Yield Topics

Pathologic Fracture

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Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Pathologic Fracture

Pathologic Fracture
Frank J. Frassica MD
Basics
Description
  • A pathologic fracture occurs through diseased bone rather than through normal bone.
    • The normal bone is replaced by abnormal bone or no bone at all.
      • The involved bone is no longer able to withstand normal physiologic forces.
      • Fracture often occurs with activities of daily living.
      • The weakened state may be caused by a benign or malignant process.
Geriatric Considerations
  • Pathologic fractures in the geriatric patient are most likely secondary to bone metastases, multiple myeloma, and lymphoma.
  • Occasionally, a destructive lesion such as a chondrosarcoma or malignant fibrous histiocytoma is the cause of the fracture.
Pediatric Considerations
  • In children and adolescents, the most common benign cause of a pathologic fracture is a unicameral bone cyst or a NOF.
  • The 2 malignancies that may cause a pathologic fracture are osteosarcoma and Ewing sarcoma.
General Prevention
  • No preventative measures if the patient is unaware of the pathologic process
  • Many patients do have antecedent pain with activity.
    • The pain usually is directly referable to the involved bone.
Epidemiology
  • Pathologic fractures usually are caused by well-recognized conditions in children, adolescents, and adults.
    • Children and adolescents:
      • Benign: Unicameral bone cysts (proximal humerus and femur), NOF, fibrous dysplasia
      • Malignant: Osteosarcoma, Ewing sarcoma
    • Adults:
      • Benign: Giant cell tumor, fibrous dysplasia
      • Malignant: Metastases, myeloma, lymphoma, malignant fibrous histiocytoma
    • Geriatric patients:
      • Benign: Hyperparathyroidism (rare)
      • Malignant: Metastases, myeloma, lymphoma, chondrosarcoma, malignant fibrous histiocytoma
Risk Factors
  • Bone strength is weakened substantially when >50% cortical bone destruction occurs.
    • Measure on AP and lateral radiographs.
    • CT scans are excellent for defining bone loss if it is not apparent on radiographs.
Genetics
No specific genetic associations are known.
Pathophysiology
  • Any defect in the cortex of a long bone results in diminished capacity to withstand forces.
    • 50% symmetric cortical involvement results in a 60% reduction in bending strength (1).
    • 50% asymmetric cortical involvement results in 90% reduction in strength (1).
    • Long lytic defects (length longer than the diameter of the bone) result in up to 90% reductions in torsional strength (1).
Associated Conditions
Any condition that substantially weakens the bone by replacing normal bone tissue
Diagnosis
Signs and Symptoms
  • Pain and bone tenderness are the 2 dominant findings
    • Bone pain: Before fracture, patients may note moderate or severe pain with ambulation.
    • Bone tenderness: Palpation often will cause severe pain.
    • Once complete fracture has occurred, patients will note severe pain that is excruciating with any motion or palpation.
History
  • Bone pain:
    • Begins intermittently and then occurs with all activities
    • Characteristically occurs before fracture
Physical Exam
  • Before pathologic fracture, physical examination findings may be few or nonexistent.
    • Palpate for bone tenderness.
    • Palpate for a soft-tissue mass that sometimes is present in malignancies.
    • Check ROM gently so as not to cause a pathologic fracture.
Tests
Imaging studies are the major modalities.
Lab
Serum tests are not helpful.
Imaging
  • Radiography:
    • Once a pathologic fracture has occurred, plain radiographs are the major diagnostic modality.
    • AP/lateral plain radiographs are used to look for the cause.
      • Look for lytic bone destruction.
      • Look for host bone reaction: Sclerotic rim, thickening of cortex
  • CT:
    • Once a pathologic fracture has occurred, CT can be used on a limited basis to aid in the diagnostic evaluation.
    • Can show the pattern of bone destruction and an approximate assessment of a soft-tissue mass
  • MRI:
    • Once a pathologic fracture has occurred, MRI can be used on a limited basis to aid the diagnostic evaluation.
    • Can be used to evaluate for soft-tissue masses and extent of marrow involvement
Diagnostic Procedures/Surgery
  • The evaluation strategy is based on the assessment of the plain radiographs.
    • If the radiographs suggest a malignant process:
      • Chest radiograph, chest CT, and abdominal
        CT to look for a carcinoma or metastases from the lesion causing the
        pathologic fracture
      • Needle or open biopsy after the staging evaluation is complete
    • If the radiographs suggest a benign process:
      • If the plain radiographs are diagnostic
        (unicameral bone cyst, NOF, fibrous dysplasia), treatment can be
        planned and initiated without a biopsy.
      • If plain radiographs are not diagnostic, a biopsy is necessary.
Pathological Findings
Depend on the nature of the underlying lesion

P.317


Differential Diagnosis
  • The differential diagnosis varies based on the age of the patient and the plain radiographs.
    • Young patient, benign appearance:
      • Unicameral bone cyst
      • NOF
      • Fibrous dysplasia
    • Young patient, malignant appearance:
      • Osteosarcoma
      • Ewing sarcoma
    • Adult patient, malignant appearance:
      • Metastatic disease
      • Myeloma
      • Lymphoma
Treatment
Initial Stabilization
  • Many patients have bone pain with activity, and it may occur weeks to months before pathologic fracture.
    • When activity-related pain exists with a
      radiographically documented destructive lesion, an ambulatory support
      to reduce loading should be recommended.
      • Walker
      • 2 crutches
      • Single cane
General Measures
  • Control pain.
  • Reduce forces with walking aid or by placing patient at bed rest.
Activity
  • Reduce activity.
    • Recommend ambulatory aid.
    • If patient is unable to walk, recommend a wheelchair.
    • If unable to control pain, recommend bed rest.
Nursing
  • Assess patient and recommend general measures:
    • Walking aid
    • Activity reduction
Special Therapy
Radiotherapy
  • Often used after pathologic fractures are treated surgically.
  • Specific indications include:
    • Metastatic bone disease
    • Multiple myeloma
    • Lymphoma
Physical Therapy
  • Used before and after surgery:
    • Before surgical stabilization:
      • Instruct patient on protected weightbearing with walking aid.
    • After stabilization:
      • Instruct patient on use of walking aid.
      • Begin program to regain strength.
Medication
  • Pain medications used as necessary
  • Diphosphonates for metastatic bone disease and multiple myeloma
Surgery
  • Pathologic fractures usually are treated with an internal fixation device such as an intramedullary nail.
    • Hip replacement is used for femoral neck fractures.
    • Patients with pathologic fractures
      secondary to sarcomas, such as osteosarcoma, usually are treated with a
      cast and then wide resection after several cycles of chemotherapy.
Follow-up
  • Patients are followed at 1-month intervals until the fracture heals.
    • Plain radiographs are used to assess healing.
Disposition
Issues for Referral
Patients are referred to an orthopaedic oncologist for management.
Prognosis
  • The prognosis depends entirely on the underlying process.
  • Benign diagnoses: Excellent
  • Malignant diagnoses:
    • Metastases (uniformly fatal, median survival)
    • Lung, kidney: 6–12 months
    • Breast, prostate: 24–48 months
    • Myeloma: Median survival, 3–5 years (2)
    • Lymphoma: 60–80% survival at 5 years (3)
    • Osteosarcoma: 60–70% survival at 5 years (4)
Complications
  • Related to the surgery:
    • Infection
    • Delayed wound healing
    • Failure to heal
Patient Monitoring
1-month intervals until the fracture heals
References
1. Hipp JA, Springfield DS, Hayes WC. Predicting pathologic fracture risk in the management of metastatic bone defects. Clin Orthop Relat Res 1995;312:120–135.
2. McCarthy
EF, Frassica FJ. Plasma cell dyscrasia. In: Pathology of Bone and Joint
Disorders: With Clinical and Radiographic Correlation. Philadelphia: WB
Saunders, 1998:185–193.
3. McCarthy
EF, Frassica FJ. Primary bone tumors. In: Pathology of Bone and Joint
Disorders: With Clinical and Radiographic Correlation. Philadelphia: WB
Saunders, 1998:195–275.
4. Hornicek
FJ. Ewing’s sarcoma. In: Menendez LR, ed. Orthopaedic Knowledge Update:
Musculoskeletal Tumors. Rosemont, IL: American Academy of Orthopaedic
Surgeons, 2002:195–202.
Miscellaneous
Codes
ICD9-CM
733.10 Pathologic fracture
Patient Teaching
Patients are instructed on the nature of the underlying lesion.
Activity
Protected weightbearing until fracture union occurs
Prevention
Prophylactic fixation often is recommended if the weakened bone state is detected before the fracture occurs.
FAQ
Q: What is the most common cause of a pathologic fracture in the adult patient?
A: Bone metastases and myeloma are the most common causes.

Q: How long does it take for a pathologic fracture to heal?
A: In general, ~6–10 weeks, depending on the fracture pattern and the amount of bone loss.

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