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Flashcards in Miller- Ortho Onc Bone Deck (40)
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31

Review Unicameral bone cysts

Presentation

Patient less than 30 years old presents with pain, usually after a fracture caused by minor trauma (e.g., sporting event, throwing a baseball, wrestling).

Occurs most often in the proximal humerus; other sites are the proximal femur and distal tibia.

Imaging

Symmetric cystic expansion with thinning of the involved cortices (Fig. 9.26in Table 9.25)

Affected bone is often expanded; however, the bone is generally no wider than the physis.

Often appears trabeculated

When the cyst abuts the physeal plate, the process is called active; when normal bone intervenes, the cyst is termed latent.

Histology: Thin, fibrous lining contains fibrous tissue, giant cells, hemosiderin pigment, and a few chronic inflammatory cells.

Treatment

Asymptomatic: Observation

Symptomatic: Aspiration and injection (bone aspirate, bone graft substitute, or methylprednisolone acetate may be used)

Unicameral bone cysts in high-stress areas (e.g., proximal femur) are often treated with curettage, grafting, and internal fixation to avoid fracture and osteonecrosis.

32

Review Langerhans Histocystosis

Occurs as three entities:

LCH monostotic, also known as eosinophilic granuloma. Only a single bone or, on occasion, multiple bones involved. Most common.

LCH polyostotic plus visceral disease, or Hand-Schüller-Christian disease

LCH polyostotic plus visceral disease in an infant, or Letterer-Siwe disease

The cellular abnormality is a proliferation of the Langerhans cells of the dendritic system.

LCH monostotic

Presentation: Pain and swelling

Imaging

The lesion is lytic and has well-defined margins, described as “punched out” (Fig. 9.27).

Cortex may be destroyed, and a periosteal reaction with a soft tissue mass simulating a malignant bone tumor may be present.

Often there are different amounts of bone destruction of the involved cortices, resulting in the appearance of a bone within a bone.

There may be expansion of the involved bone.

Any bone may be involved.

Histology

The proliferating Langerhans cell, with an indented or grooved nucleus, is the characteristic cell.

Cytoplasm is eosinophilic.

Nuclear membrane has a crisp border.

Mitotic figures may be common.

Bilobed eosinophils with bright, granular, eosinophilic cytoplasm are present in large numbers.

Electron microscopy shows a tennis racquet–shaped Birbeck granule.

Treatment: LCH is a self-limiting process that often resolves after biopsy and/or curettage.

LCH polyostotic plus visceral disease: Hand-Schüller-Christian disease

Bone lesions and visceral involvement

Classic triad, which occurs in fewer than one fourth of patients, consists of exophthalmos, diabetes insipidus, and lytic skull lesions.

Multifocal disease is usually treated with chemotherapy.

Letterer-Siwe disease occurs in young children and is usually fatal.

33

Review Fibrous Dysplasia

Developmental abnormality of bone that is characterized by monostotic or polyostotic involvement and is the failure of the production of normal lamellar bone.

Presentation

Pain from a fracture or stress fracture; or an incidental finding if asymptomatic; café au lait spots with irregular borders (resembling the coast of Maine) may accompany the bone lesions.

Any bone may be involved; the proximal femur is the most commonly affected.

Imaging: Variable appearance that can look highly lytic or like ground glass (Fig. 9.29)

Histology

Well-defined rim of sclerotic bone

Proliferation of fibroblasts (produces a dense collagenous matrix)

Trabeculae of osteoid and bone within the fibrous stroma are present in a disorganized manner, and their appearance has been likened to “alphabet soup” and “Chinese letters.”

Treatment

Predicated on the presence of symptoms and the risk of fracture

Internal fixation and bone grafting are used in areas of high stress in which nonoperative treatment would not be effective.

Most affected patients do not need surgical treatment.

Autogenous cancellous bone grafting is never used because the transplanted bone is quickly transformed into the woven bone of fibrous dysplasia. Cortical or cancellous allografts are usually used.

Bisphosphonate therapy has been shown to be effective in decreasing pain and reducing bone turnover in patients with polyostotic fibrous dysplasia.

Other features

Genetic mutation is an activating mutation of the GSα surface protein (GNAS)

Increased production of cAMP

When endocrine abnormalities (especially precocious puberty) accompany multiple bone lesions and skin abnormalities, the condition is called McCune-Albright syndrome.

34

Review OSTEOfibrous dysplasia

Presentation: Patients present before 30 years of age, commonly with tibial disease in which bowing is very common, and affected children may experience pathologic fractures.

Imaging: Primarily involves the tibia and is usually confined to the anterior tibial cortex (Fig. 9.30).

Histology: Fibrous tissue stroma and a background of bone trabeculae withosteoblastic rimming.

Treatment

Nonoperative treatment is preferred until the child reaches maturity.

Resection or fixation or both may be required

35

Difference between Fibrous dysplasia, osteofibrous dysplasia and Adamantinoma

36

Review Pagets Disease of Bone

Characterized by abnormal bone remodeling

Presentation

Patient over 50 years old presenting with pain.

Patient may present with degenerative joint disease, fracture, or neurologic encroachment; joint degeneration is common in the hip and knee.

Monostotic or polyostotic

Imaging: Radiographs demonstrate coarsened trabeculae and remodeled cortices. Coarsened trabeculae give the bone a blastic appearance.

Histology: Characteristic features are irregular, broad trabeculae; reversal or cement lines; osteoclastic activity; and fibrous vascular tissue between the trabeculae.

Treatment

Aimed at retarding the activity of the osteoclasts

Agents used include diphosphonates and calcitonin (pamidronate and zoledronic acid).

Patients undergoing arthroplasty should be treated with bisphosphonates to decrease bleeding at the time of surgery.

Other features

Fewer than 1% of patients with Paget disease experience malignant degeneration with the formation of sarcoma within a focus of a Paget lesion.

Symptoms of Paget sarcoma are the abrupt onset of pain and swelling.

Radiographs usually demonstrate cortical bone destruction and the presence of a soft tissue mass.

Paget sarcoma is a deadly tumor with a poor prognosis (rate of long-term survival is <20%).

37

Review osteomyelitis

Bone infections often simulate primary tumors.

Presentation: Patient of any age may present with fever, chills, bone pain, or a combination of these symptoms.

Imaging

Bone destruction and formation are the characteristic findings of chronic infections.

Acute infections often produce cortical bone destruction and periosteal elevation.

Serpiginous tracts and irregular areas of bone destruction are suggestive of infection rather than neoplasm.

Histology: A mixed-cell population of inflammatory cells, plasma cells, polymorphonuclear leukocytes, eosinophils, lymphocytes, and histiocytes

Treatment: Resection of necrotic bone and appropriate antibiotic therapy

Other features: A chronic infection with long-standing wound drainage is occasionally complicated by squamous cell carcinoma.

38

treatment decisions for pathologic fracture

Overall treatment aimed at controlling pain and maintaining the independence of the patient

Prophylactic internal fixation is performed when impending fracture is deemed likely.

In comparison with treatment of completed pathologic fractures, prophylactic fixation results in less blood loss, shorter hospital stays, greater likelihood of discharge to home, and greater likelihood of independent ambulation.

There are many suggested criteria for fixation. The following conditions put the patient most at risk for fracture:

More than 50% destruction of the diaphyseal cortices

Permeative destruction of the subtrochanteric femoral region

More than 50%–75% destruction of the metaphysis

Persistent pain after irradiation

Pain on weight bearing (especially in lower extremity with every footstep)

Treatment of pathologic fractures is almost always surgical, inasmuch as these fractures rarely have the potential to heal.

Surgical procedures should not rely on bony healing.

Most proximal femur fractures should be treated with an endoprosthesis, to protect the femoral shaft in patients with relatively long life expectancy.

Risk factors for sudden death during insertion of a long-stem prosthesis: presence of breast cancer, hypovolemia, reduced pulmonary function

39

Pagets Review

Orthobullets

Introduction

A condition of abnormal bone remodeling

original osseous tissue is reconstructed through active interplay between excessive bone resorption and abnormal new bone formation  

Pathophysiology

increased osteoclastic bone resorption is the primary cellular abnormality  

cause is thought to be a slow virus infection (intra-nuclear nucleocapsid-like structure) 

paramyxovirus

respiratory syncytial virus

Epidemiology 

peak incidence in the 5th decade of life

common in Caucasians (northern European / Anglo-Saxon descent)

males = females

location 

may be monostotic or polyostotic

common sites include femur > pelvis > tibia > skull > spine 

Genetics inheritance 

most cases are spontaneous

hereditary 

familial clusters have been described with ~40% autosomal dominant transmission

genetics most important is 5q35 QTER (ubiquitine binding protein sequestosome 1) SQSTM1 (p62/Sequestosome) 

tend to have severe Paget disease

also insertion mutation in TNFRSF11A for gene encoding RANK

Orthopaedic manifestations 

bone pain

long bone bowing

fractures, due to brittle bone and tend to be transverse

large joint osteoarthritis

excessive bleeding during THA

malalignment during TKA

secondary sarcoma

Associated conditions

high output heart failure

Prognosis & malignancy Paget's sarcoma

less than 1% will develop malignant Paget's sarcoma (secondary sarcoma)

osteosarcoma > fibrosarcoma and chondrosarcoma  

most common in pelvis, femur, and humerus

poor prognosis 

5-year survival for metastatic Paget's sarcoma < 10% 

treatment includes chemotherapy and wide surgical resection 

Classification

Phases lytic phase 

intense osteoclastic resorption

mixed phase 

resorption and compensatory bone formation

sclerotic phase 

osteoblastic bone formation predominates 

all three phases may co-exist in the same bone

Presentation

Symptoms asymptomatic

frequently asymptomatic and found incidentally

painpain may be the presenting symptom due to 

stress fractures

increased vascularity and warmth

new intense pain and swelling

suspicious for Paget's sarcoma in a patient with history of Paget's + new intense pain and swelling

cardiac symptoms

can present with high-output cardiac failure particularly if large/multiple lesions & pre-existing diminished cardiac function

Imaging

Radiographs coarsened trabeculae which give the bone a blastic appearanceboth increased and decreased density may exist depending on phase of disease lytic phase 

lucent areas with expansion and thinned, intact cortices

'blade of grass' or 'flame-shaped' lucent advancing edge

mixed phase 

combination of lysis + sclerosis with coarsened trabeculae

sclerotic phase 

bone enlargement with cortical thickening, sclerotic and lucent areas   

remodeled cortices

loss of distinction between cortices and medullary cavity

long bone bowing

bowing of femur or tibia 

fractures 

hip and knee osteoarthritis

osteitis circumscripta

(cotton wool exudates) in skull 

Paget's secondary sarcoma 

shows cortical bone destruction

soft tissue mass

MRI 

may show lumbar spinal stenosis

Bone scan 

accurately marks site of disease

intensely hot in lytic and mixed phase

less hot in sclerotic phase

CT scan

cortical thickening and coarsened trabeculae

Evaluation

Laboratory findings 

elevated serum ALP

elevated urinary collagen cross-links

elevated urinary hydroxyproline (collagen breakdown marker)

increased urinary N-telopeptide, alpha-C-telopeptide, and deoxypyridinoline

normal calcium levels

Histology

Characteristic histology 

woven bone and irregular broad trabeculae with disorganized cement lines in a mosaic pattern    

profound bone resorption - numerous large osteoclasts with multiple nuclei per cell 

virus-like inclusion bodies in osteoclasts  

Paget's osteoclasts larger, more nuclei than typical osteoclasts

fibrous vascular tissue interspersed between trabeculae

Treatment

Nonoperativeobservation and supportive therapy  treatment for asymptomatic Paget's disease

physiotherapy, NSAIDS, oral analgesics

medical therapy aimed at osteoclast inhibition  bisphosphonates are 1st line treatment for symptomatic Pagetsoral

alendronate and risedronate

etidronate disodium (Didronel) 

older generation medication

inhibits osteoclasts and osteoblasts

cannot be used for more than 6 months at a time

intravenouspamidronate, zoledronic acid (Zometa)

newer generation medications that only inhibit osteoclasts

disadvantageous in that they only come in IV form

calcitonin are 2nd line (after bisphosphonates)

causes osteoclasts to shrink in size and decreases their bone resorptive activity within minutes

administered subcutaneously or intramuscularly

teriparatide is contraindicated in Paget's disease due to risk of secondary osteosarcoma 

OperativeTHA / TKAindications

affected patients with degenerative joint disease

technique

treat Paget's with pharmacologic agents prior to arthroplasty to reduce bleeding

outcomes

greater incidence of suboptimal alignment secondary to pagetoid bone

the most common complications include 

malalignment with knee arthroplasty 

bleeding with hip arthroplasty

metaphyseal osteotomy and plate fixation   indications

fractures through pathologic bowing of long bones 

impending pathologic fracture of long bone with bowing

40

Risk factors for heterotopic ossification