Orthopedic Surgery Grand Round7th February 2013Dr. J.W. Kinyanjui

Registrar Ward 6D

OutlineIntroduction

Epidemiology

Pathophysiology

Clinical evaluation

Management

IntroductionFracture through abnormal bone

Minor trauma or during normal activity

5th decade most prevalent

Metastases 2nd most common cause of pathologic fractures

F: breast and lungs – 80%

M: prostate and lungs – 80%

10% - no primary tumor found

Epidemiology – incidence at autopsyPrimary Site % metastasis to

BoneBreast 50-85Lung 30-50Prostate 50-70Hodgkin’s 50-70Kidney 30-50Thyroid 40Melanoma 30-40Bladder 12-25

PathophysiologyMost spread is hematogenous

Few tumors due to contiguous spread

Most common osteolytic via osteoclast stimulation

Prostate – commonly osteoblastic

Breast – mixed

Theories explaining predilection of bone for metastasis

Paget’s fertile soil hypothesis1889

Sites of secondary growths are not a matter of chance

Some organs provide a more fertile environment for the growth of certain metastases

Example: breast cancer to liver, Krukenberg tumor

Prostate cancer to bone

Hart and fielder later proved this using radioactive labelling

Ewing’s circulation theory1928

Metastatic deposits dependent on route of blood and lymph flow

Organs though to be passive receptacles

Organs with prominent venous systems have more secondaries

Baston plexus of spine responsible for prostate secondaries

Red marrow theoryIn descending order of frequency:

SpinePelvisRibsProximal appendicular skeleton

Marrow sinusoids more susceptible to tumor cell penetration

Sudden change from arterioles to sinusoids favours tumor cell entrapment

Ewing’s and Paget’s theories not mutually exclusive

Molecular levelCells from primary enter blood vessels

Attachment and penetration of basement membrane, neovascularisation

Type 1 collagen shown to be chemotactic to tumor cells

RANK ligand produced by tumor cells stimulating osteoclast activity

PTHrP produced by breast and lung cancer cells stimulates osteoclasts

Prostate cancer cells produce BMPs, IGF1, TGFβ2 which stimulate osteoblasts

Clinical evaluation: HistoryPain – most common, preceding fracture, night,

constant, dull, aggravated by activity

Trauma – usually minimal for type of fracture

Constitutional – anorexia, night sweats, weight loss, fatigue

Previous cancer

Carcinogen – smoking, radiation, occupational toxins

Factors suggesting pathologic fractureSpontaneous fracture

Minor trauma

Pain at site preceeding fracture

Multiple recent fractures

Age > 45 yrs

Prior history of malignancy

Associated problemsLowered Quality of life:

Debilitating pain

Immobility

Neurologic deficits – spine mets

Anaemia

Hypercalcemia

HypercalcemiaNeurologic: headache, confusion, irritability,

blurred vision

Gastrointestinal: anorexia, nausea, vomiting, abdominal pain, constipation, weight loss

Musculoskeletal: fatigue, weakness, joint and bone pain, unsteady gait

Urinary: nocturia, polydypsia, polyuria, urinary tract infections

Clinical evaluation: examinationLocal: mass, deformity, tenderness,

contiguous skeleton, neurologic exam

Systemic: cachexia, pallor, lymphadenopathy, entire skeletal system

Primary: breast, thyroid, prostate, lung, pelvic

Clinical evaluation: LaboratoryTBC – anaemia of chronic disease

Calcium – elevated

Alkaline phosphatase – elevated, non specific

Tumor markers – PSA, CEA, CA125, TFTs

N-telopeptide + C-telopeptide – markers of bone destruction, determine extent of skeletal involvement, assess response to bisphosphonates

Imaging: plain radiographsEnneking’s questions:

Location: diaphysis, metaphysis, epiphysis, cortical or medullary

Effect: osteoblastic vs. osteolytic or mixed

Reaction: sclerotic rim, periosteal reaction, codman triangle

Isolated avulsion of lesser trochanter – imminent femoral neck fracture

Osteolytic, diaphyseal medullary, periosteal reaction

Osteoblastic mets to bone

Codman triangle

Osteolytic lesion in lesser trochanter

Radiology: CT scans

Most sensitive for detecting bone destruction

Determines extent of cortical involvement

Also used to search for primary lesion in pelvis, abdomen or chest

Mixed lesion in lung mets

Radiology: MRI

Most sensitive for assessment of the anatomic extent of a lesion

Most adequate for spinal metastases to determine neurologic structure involvement

Can determine extraosseous spread of a mass

Bone scanningTechnetium-99m (99m Tc) bone scanning:

Sensitive for detection of occult lesions

Assessment of the biologic activity of lesions

Identification of other sites

Assessing response to therapy

BiopsyIndicated to rule out primary tumor of bone

Immunohistochemistry can determine primary

Biopsy at fracture site complicated by bleeding and callus formation

Needle vs incisional

Oncological surgical principles adhered to

Cultures to rule out infection

Impending pathologic fracturesProphylactic stabilisation before radiotherapy

can be performed for pain

Radio and chemotherapy without stabilisation also an option

Decision to stabilise difficult

Mirel’s criteria useful to determine which lesions at high risk of fracture

Mirel’s criteriaVARIABLE SCORE

SITE Upper Limb Lower Limb Peritrochanteric

PAIN Mild Moderate Severe

LESION Blastic Mixed Lytic

SIZE <1/3 1/3 – 2/3 >2/3

Size is the diameter of cortex involved on plain radiographsA score of 8 or more is an indication for prophylactic stabilisation

AdvantagesProphylactic stabilisation:

Shorter hospital stay

More immediate pain relief

Faster and less complex surgery

Quicker return to premorbid function

Improved survival

Management objectivesDecrease pain

Restore function

Maintain/restore mobility

Limit surgical procedures

Minimize hospital time

Early return to function (immediate weightbearing)

Non operative managementBisphosphonates – modifies bone resorption by

osteoclasts, shown to reduce risk of skeletal metastasis

Hematologic – correction of anaemia, coagulopathy, DVT prophylaxis

Hypercalcemia – hydration, calcium restriction, bisphosphonates, mithramycin

Analgesia

Radiation – most useful in spinal metastases

RadiotherapyUsed to reduce pain secondary to bone metastases

Partial in 80%. Complete in 50 – 60%

Halts progression of bony destruction

Allows healing of an impending pathologic fracture

Postoperative local tumor control

Bracing

Patients with limited life expectancies, severe comorbidities, small lesions, or radiosensitive tumors

Upper extremity lesions particularly amenable

Adjuvant radiotherapy of suscepible tumors required

Operative: principlesDurable, weight bearing impalnts needed

PPMA augmentation of construct useful incl. prosthesis

Bone graft less useful due to prolonged healing time

Prophylactically stabilise as much bone as possible

Anticipate hemorrhage due to neovascularisation

Thus tourniquet, preoperative embolisation

Upper extremityScapula, clavicle – non operative

Proximal humerus – prosthesis (long stem), intramedullary nail with multiple screws

Humerus Diaphysis – locked IM nail > plating

Distal humerus – prosthesis, retrograde flexible IM nails > bicondylar plating

Forearm – Rare. IM nails or plating

Lower extremityAcetabular – reconstruction with appropriate

prosthesisFemoral neck – hemi- or THR. Cemented. Long

stemIntertrochanteric – recon nail or prosthesis >

DHSSubtrochanteric – locked IM nailFemur shaft – locked IM nail preferably

cephalomedullaryAround the knee – locked plating > retrograde

nailing

Spinal fracturesCommonly present with compression fracture

MRI to differentiate from osteoporosis

Lesion involving body and pedicle sparing disc highly suggestive

Radiotherapy, steroids if no neurodeficits or impending fracture

Spinal fracturesSurgery:

Progression of disease after radiationNeurologic compromiseImpending fractureSpinal instability due to pathologic fractureProgressive deformity due to pathologic

fractureOptions:

Minimally invasive kyphoplasty/vertebroplastyDecompression and instrumentation

Controversies and future trendsOptimal length of femoral component of THRCriteria for impeding fractureWide resection of solitary metastases – RCCRadiofrequency ablationCryotherapyAcetabuloplasty – percutaneous PMMA

injectionRANK L modificationAngiogenesis inhibitors

SummaryDiagnosis and treatment requires a

multidisciplinary approach

Aggressive surgical treatment relieves pain, restores function, and facilitates nursing care

Biopsy all solitary lesions or refer appropriately

Understand tumor biology and tailor treatment

THANK YOU