BS/TUMOR

- Type x collagen is important for mineralization (locations include in cartilage deep to the tidemark and in the ZPC of the growth plate)
- Myositis Ossificans should not be resected until completely ossified
- Desmoid tumors contain E receptors and Tamoxifen is useful in the Treatment
- A mutation in CBFA 1 leads to Cleidocranial Dysplasia
- Chromium and Tantulum are very resistant to corrosion
- Molybdenum is added to cobalt alloys to increase strength
- IGN is the sole motor innervation of gluteus maximus
- Lipomas are bright on T1
- Osteoarthritis leads to increase water and decreased proteoglycans and collagen in cartilage (very commonly asked)
- CD 31 is a sensitive marker for angiosarcoma
- AIIS is the origin of Rectus Femoris
- Anakinra is an IL-1 antagonist used as Tx of RA
- Etaneracept and Adalimumab block TNF alpha in the Tx of RA
- TOC for PVNS is total synovectomy
- Joint motion improves chondrocyte nutrition
- Synovial Chondromatosis is a benign metaplastic process of joints that leads to stippled calcifications and loose bodies
- If PE is irradiated in air, catastrophic failure and delamination occur
- Osteocalcin is the most abundant non collagenous protein in bone
- High Rates of Telomerase results in increased recurrence rates in patients with chondrosarcoma
- X linked hypophosphatemic rickets caused by mutation in the PEX gene; MHE caused by defects in the EXT-1 or 2 genes
- Synovial Sarcoma a/w translocation of X;18, Ewings with t(11;22)
- Tumor related Osteolysis is mediated by the RANKL pathway
- After IMN of pathologic fracture secondary to mets, Radiation to the entire bone is warranted (NOT just the initial tumor site)
- Skin manifestations (rash…) are common in Eosinophilic Granuloma
- The mechanical properties of viscoelastic structures such as tendons depend on the rate of the applied load
- isotropic materials display the same mechanical properties in all directions of the applied load
- Elastin in the protein responsible for the toe region of a stress strain curve
- Appropriate preop work up of an atrophic Nonunion should include: smoking cessation, Ca/Vit D levels, PTH/TSH levels, etc. etc.
- Renal osteopdystophy results in hyperphosphatemia and hypocalcemia (damaged kidneys cant excrete phosphate)
- Anakinra is an IL 1 antagonist used in the Tx of RA
- Adalimumab and Etaneracept are both TNF alpha inhibitors
- Titanium is extremely biocompatible because it forms a stable oxide that is relatively inert (TIO2)
- Clindamycin is bacteriostatic, bacitracin is Bacteriocidal
- Brittle Materials do not undergo plastic deformation, ductile materials undergo quite a bit before failure
- Increasing pin length will decrease the rigidity of an ex fix
- Osteopetrosis is caused by a defect in Carbonic Anhydrase Enzyme
- Retinoblastoma and Neurofibromin are commonly tested tumor suppressor genes
- PTH receptors are located on osteoblasts!! Osteoclast have receptors for calcitonin
- MC collagen in cartilage is type 2, in ligaments is type 1, in blood vessels in type 3
- MMP is an enzyme that degrades basement membranes and assist in the metastasis of cancer
- CXR is normal in fat emboli syndrome
- MC epiphyseal lesion in a Kid is chondroblastoma
- Synovial Cell Sarcoma a/w fusion b/w SYT/X…
- Ewings Sarcoma classically has t(11:22), need bone marrow Bx as part of the work up
- Sarcomas that go to lymph nodes: CASE: Clear Cell, Alveolar Rhabdo, Synovial Cell, and Epitheloid
- Cartilage lesions superficial to the tidemark are unlikely to heal
- Type X cartilage important for mineralization, present in the ZPC of growth plate
- Fibrous Dysplasia is MC in the diaphysis of long bones
- Most common sites for both adamantinoma and osteofibrous dysplasia is the anterior cortex of the tibia
- Histology with predominance of hemosiderin laden macrophages is characteristic of PVNS
- Ewing sarcoma and Lymphomas are classic for having elevated ESR, WBC, and Leukocytosis, BM Bx part of workup for Ewings!
- Fibrous Dysplasia histology often described as alphabet soup or Chinese letters
- Patients with Rb gene have increased risk of osteosarcomas
- Soft tissue sarcomas as a whole respond poorly to chemo, generally, surgery and radiation are TOC
- In general ST sarcomas are dark on T1 and Bright on T2
- SCC classic for developing in areas of chronic inflammation such as burns or osteomyelitis
- Amount of tumor necrosis after chemo is directly proportional to prognosis in osteosarc (more is better)
- Fibrous Dysplasia classically affects diaphysis of long bones
- Strong negative birefringence under polarized light a/w gout, positive with pseuodogout
- Fluid/fluid levels on MRI are classic for ABC
- Osteofibrous dysplasia and Adamnantinoma occur in the anterior tibial cortex, Bx necessary to differentiate
- Chondroblastoma is the MC epiphyseal lesion in Kids, look for chicken wire calcification and grooved nuclei
- Physaliferous cells are present in chordoma!
- Survival in osteosarc is the same in limb salvage vs amputation
- MC location of a parosteal osteosarc is the posterior distal femur
- Elevated levels of B2 microglobulin afford worse prognosis is multiple myeloma
- Soft Tissue Sarcomas that can metastasize to lymph nodes =CASE (clear cell, Alveolar Rhabdo, Synovial cell, epitheliod)
- Synovial Cell is a/w t(x;18)
- 4 surgical margins described by Enneking: intralesional, marginal, wide, radical
- Mutations in Ext 1 or 2 a/w MHE; 1 has worse prognosis
- Rhabdomyosarc and Synovial sarc are unique because they may show benefit to tx with chemo
- Multiple enchondromatosis is AKA Olliers disease
- MC lymphoma of bone is large B cell (non hodgkins)
- MC benign bone tumor of childhood is NOF
- Osteoblastomas are the “big brother” of osteoid osteomas but are larger and less responsive to NSAIDS
- Bence Jones Proteins (light chains of Immunoglobulins) are found in the urine of MM patients
- Lipomas, the MC soft tissue masses are bright on T1 and dark on T2
- “Smoke up the Chimney” lesion in the metaphysic is classic for bone infarct, lesion appears serpiginous on MRI
- Birbech Granules are seen on electron microscopy in Eosinophilic Granulomas/Langerhand Histiocytosis
- Classic Triad of Glomus Tumor= cold intolerance, paroxysmal pain, and Tenderness to palpation
- Degrees of nerve injury in increasing severity: neuropraxia (secondary to compression), axonotmesis (axons are cut), neuronotmesis (axon, epineurium, endoneurium all damaged)
- MC sarcomas of young adults are synovial cell and epitheliod
- Linezolid inhibits protein synthesis by binding to the 23 S portion of the 50 S subunit
- Lisch Nodules are benign hamartomas of the Iris in NF
- In severe Osteoarthritis, cartilage has increased water and decreased Proteoglycans
- Sarcomas are of mesenchymal origin, an thus stain + with vimentin
- Both endochondral ossification and intramembranous ossification are forms of secondary bone healing
- Lactating women need 2000 mg of calcium/day, elderly need 1500
- Microfracture of an osteochondral defect leads to healing with type 1 fibrocartilage, not the normal type 2 hyaline stuff
- The tidemark is the jxn between mineralized and unmineralized cartilage, lesions superficial to this are unlikely to heal secondary to poor blood flow
- In nutritional rickets, PTH is high, in x linked hypophosphatemic rickets (mutated PHEX gene), PTH is not
- t(x;18) leads to formation of the fusion gene syt-ssx and is a/w synovial sarcoma
- -osteopetrosis is secondary to a carbonic anhydrase deficiency within osteoclast
- In chronic osteomyelitis, removal of the sequestrum is mandatory to completely eradicate (OITE last Year)
- Satellite Cells are responsible for repairing muscle
- The Myofibroblast is the offending cell in Depuytrens Conrtacture
- Much high doses of radiation are used to prevent HO (600 cGy) than are used in the treatment of Soft tissue Sarcomas (60 cGy)
- Chondrocalcinosis on xray is typical for CPPD. Surgery can flare up an attack!! -The Youngs modulus of cement is less than cortical bone
- Toughness is equal to the area underneath the stress/strain curve
- E=Stress/Strain
- Morquio syndrome is different from the other mucopolysacharridoses because an accumulation of keratin Sulfate (not Heparin sulfate or dermatan sulfate) occurs
- The gait cycle is 60% stance and 40% swing phase. In an antalgic gait, the swing phase is accelerated on the unaffected side to minimize stance on the hurt extremity
- Myositis Ossificans most commonly affects the quadriceps. Calcification occurs from the periphery toward the center of the lesion with time (useful to distinguish it from extraosseous Osteosarcoma)
- The clavicle is the only long bone to ossify by intramembranous ossification
- Fibrodysplasia Ossificans Progressiva (stone man syndrome) caused by mutations in the BMP 4 signaling cascade that leads to diffuse deposition of heterotopic bone
- The perichondrial artery is the main blood supply to the growth plate
- Mazabrauds Syndrome is characterized by multiple intramuscular myxomas and fibrous dysplasia
- Giant Cell Tumors are benign aggressive tumors found in the epiphysis of long bones
- Denosumab is a monoclonal antibody against RANKL used in the treatment of GCT
- Primary bone healing, Haversian remodeling, and healing via cutting cones are all the same thing
- Fractures treated with bridge plating, IMN, or non operatively all heal with endochondral ossification/secondary bone healing
- Parosteal osteosarcomas typically have a “stuck on” appearance, is hyperintense on bone scan, and histology showing mature appearing bone without pleomorphic features
- Melorrheostosis is a benign condition characterized by flowing hyperostosis that replaces intramedullary canal with benign osteoid. Hot on bone scan, benign histology
- Parsonage Turner syndrome is a brachial neuritis that may or may not be a/w viral infection that leads to severe pain that is self limiting followed by weakness
- With regards to brachial plexus injuries, pre-ganglionic lesions such as root avulsions have a worse prognosis than do post ganglionic ones
- Pseudoachondroplasia is causes by a COMP mutation on chromosome 19
- Integrins such as Vitronectin play an integral role in attaching osteoclast to bone within the Howships Lacunae
- Endothelin 1 plays an important role in osteoblastic bone metastases
- A non displaced fracture through an ABC should be treated non op as sometimes the fracture stimulates the cyst to obliterate
- Ceramics have very high modulus of E and compressive strengths
- Post op radiation for HO prophylaxis is typically a single dose at 800cGy 1-4 days post-operatively
- SPEP in myeloma patients shows a monoclonal spike confirming diagnosis
- Bone Scans are cold in Multiple Myeloma!!
- The superior Gluteal nerve innervates the TFL, The GM, and Gluteus minimus!
- During the stance phase of gait, weak abductors will lead to pelvic tilt towards the contralateral side (trendelenburg sign)
- Implants with pore sizes of less than 50 microns have less shear strength than those with sizes b/w 50 and 400 microns
- In order to be phagocytosed and lead to osteolysis, wear particles must be less than 10 microns in size, larger particles contribute less to aseptic loosening
- Fast pain is carried by A fibers, slow pain by C fibers
- Substance P, Histamine, Bradykinin, Serotonin, and Prostaglandins have all been proven to cause nociceptive responses around articular structures (they cause pain)
- Osteopetrosis, (AKA Albers Schonberg Disease) is caused by an abnormal deactivating mutation in the Carbonic Anhydrase gene of osteoclasts
- No difference in the biomechanic strength of syndesmosis screw if 3 vs 4 cortices are purchased.
- Wolfs law of collagen: soft tissues subjected to abnormal stresses tend to undergo fibroblastic thickening and contracture. Ex. Posterior shoulder capsule in GIRD
- Modulus of Elasticity high to low: Ceramic>Cobalt>stainless steel>titanium and bone. Remember these basics for the test!
- An isolated lesser troch fracture in elderly is PATHOGONOMIC for a pathologic process in the proximal femur. In adolescents, it is secondary to avulsion of the psoas
- Dedifferentiated chondrosarcoma has a terrible prognosis and generally develops from a pre-existing chondroid lesion
- Uric acid is the final product of purine metabolism, always high in gout patients, but not all patients with hyperuricemia get gout
- Senile osteoporosis affects both cortical and cancellous bone
- Osteoporis is normal bone but decreased quantitiy, osteomalacia is ABNORMAL bone secondary to poor mineralization (usually due to a Vit D problem)
- Metastasis from breast and prostate are notorious for creating osteoblastic lesions
- Crescent sign is seen is stage 3 of AVN and is due to attempts at revascularization
- TOC for osteofibrous dysplasia is typically NON op! Lesions usually regress and do not cause problems
- EG is the great mimicker. When in the spine, it caused flattened vertebral bodies, vertebra plana
- Osteoid Osteomas have a high cyclooxygenase and prostaglandin level!!
- Best study to diagnose an osteoid osteoma is the thin cut CT!! MRI often just shows intense inflammation
- Contraindications for RFA of OO are lesions close to the spinal cord or nerve roots
- The posterior elements of the spine are very common locations for Osteoid osteomas and osteoblastomas.
- MC bony tumor of the hand:enchondroma
- Well defined central medullary lesion that classically has stippled calcification is an Enchondroma. Cause is thought to be incomplete endochondral ossification
- Adjuvants such as Phenol, High speed burr, or liquid nitrogen are commonly used to decrease the recurrence of UBC, ABC, GCT, and chondroblastoma after curettage
- NOF are most common in the long bones of the lower extremity
- 2% of GCT metastasize to the lungs and may require chemo, radiation, or surgery
- Cell of origin of synovial cell sarcoma is unknown; immunohistochemistry + for cytokeratin and epithelial cell membrane antigen
- EDC and EDQ are most susceptible to rupture in RA
- Caput Ulnae Syndrome: severe synovitis of the DRUJ leads to dorsal subluxation of the ulna or volar subluxation of the carpus and contributes to tendon ruptures
- Most common flexor tendon rupture in RA: FPL over scaphoid osteophyte (mannerfelts syndrome)
- LMWH functions through inhibition of factor Xa, Coumadin inhibits gamma carboxylation of factors 2,7,9,10, protein C and S
- Risk factors for HO: head injury, prolonged ventilation, severe burns, Spinal cord injury, amputation through the zone of injury. OPEN FRACTURES HAVE NOT BEEN PROVEN TO INCREASE RISK OF HO!!
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