Knee, Bone Metastases Flashcards
Primary function of the ACL and PCL in the knee
Prevent anterior and posterior motion (respectively)
Act as a 4 bar linkage preventing knee rotation, and allowing for femoral rolling on knee flexion.
Function of the patella
Acts as a fulcrum for knee extension from flexion by increasing the quad lever arm
Function of the meniscus
To distribute load across the tibia/femur joint and maintain joint congruity. The lateral meniscus shifts more than the medial during flexion.
Collagen type found in the menisci
Type I collagen (not articular cartilage)
Q angle
Angle between the tibial shaft and the patella that approximates the pull of the quadriceps
Increasing the Q angle (normal is up to 15 degrees) will increase chances of a lateral displacement of the patella
Tests used to evaluate the ACL
Anterior drawer/ Lachman’s
Pivot angle
Ligaments of the knee capable of healing
MCL and LCL only (PCL and ACL are intra-articular)
Ligament of the knee that is the primary restraint to lateral dislocation of the patella
Medial patellofemoral ligament
Grades of Knee Injuries (3)
1: Damaged ligaments without laxity
2. Partial ligament tear with laxity
3. Full tear of ligament
Three phases of ligament healing (extra-articular only)
- Inflammation, clotting
- Proliferative, increased cell density and revascularization. Collagen is disorganized
- Remodeling, reduced cell density, alignment of collagen to forces
Note that full immobilization will impede remodeling
Treatment required for ACL tears
Since ALC will not heal on its own, surgical reconstruction is needed
Radiographic Findings in osteoarthritis (4)
Asymmetric joint space narrowing (RA is symmetric)
Osteophytes
Sclerosis
Subchondral cysts
Clinical presentation of osteoarthritis
Typically affects knee or large joints, or hand
Pain is worst as day progresses (best in morning or on weekends)
Knee is the most commonly affected joint
Risk factors for developing OA of any joint (5)
Genetics
Trauma or misalignment of joint (especially hip problems in children)
Obesity or increased loads
Meniscectomy
Joint instability such as an untreated ACL tear which also tears the meniscus
Treatment options fo OA
Decrease loads/ joint use via insoles, low impact exercise, or work limitations
Lose weight
Improve ROM with stretching exercises
Improve strength and balance
If needed, arthroscopy and meniscectomy, but typically not any more effective than PT
Cause of patellofemoral pain syndrome
Develops from sudden increases in activity or training errors
Presentation of patellofemoral pain syndrome
Diffuse, aching, anterior knee pain
Motion most associated with meniscal tears
Twisting of the knee in young patients or degeneration in old
Clinical presentation of meniscal tear
Joint line pain and tenderness
Pain increases with twisting or squatting
Knee may click or catch while binding/extending
Treatment of meniscal tears
Should get an MRI to evaluate extent of damage
Menisci may heal if only torn in vascular outer third
Observation appropriate in older individuals
Cartilage transplant (after meniscectomy) or surgical correction in athletes
Motions associated with ACL tear
Jumping, pivoting, landing
Most are not associated with sports
Imaging needed for ACL tears
MRI to assess damage and determine if a meniscal tear is also present (50%)
Treatment used for ACL tears
Sedentary: non-operative
Active: ACL reconstruction (will not heal), using harvested tissue from achilles or hamstrings
Most Common soft tissue sarcomas in adults
Liposarcoma
Undifferentiated fibrosarcoma
Most common ST sarcomas in children
Rhabdomyosarcoma
Synovial sarcoma
Imaging studies typically used in soft tissue sarcomas
X-ray to assess bone involvement and periosteal reaction
MRI to assess tumor shape and involvement
Chest CT to examine for lung involvement
Most common malignant bone tumors of children
Osteogenic sarcoma (blastic) Ewing's sarcoma (lytic)
Most common benign bone lesions in children
Unicameral bone cysts
Fibrous dysplasia
Undifferentiated fibrosarcomas
MALIGNANT AGGRESSIVE soft tissue sarcoma seen in adults that commonly involves the lungs
Liposarcoma
Less aggressive (than undiff fibrosarcoma) ST sarcoma that can spread to the peritoneum or abdominal viscera
Location of most synovial sarcomas
Hands and feet (but not derived from synovial cells)
Treatment options for unicameral bone cysts
Resolve on own Only use treatment if painful or persistent after skeletal maturity. Cysts may recur. - Bone graft - Injection - Cryotherapy
Pathologic presentation of fibrous dysplasia
skeletal deformity with propensity for fracture or limb bowing (including arms)
Albright’s syndrome
Fibrous dysplasia combined with:
- Precocious puberty
- Cafe au lait
Histologic and radiographic findings in fibrous dysplasia
Lytic lesion with ground glass
Small segments of bone in a fibrous stroma
Significant finding in Ewing’s sarcoma
Blue cells that stain positive for glycogen
Treatment options for Ewing’s sarcoma
If bones are expendable: give surgery and chemotherapy
If bones are not expendable: give radiation only with similar results
Most common locations of cancer metastasis to bone
Pelvis, spine, femur, humerus
Factors influencing treatment options for patients with malignant bone metastases
Amount of pain
Size of lesion
Risk of having fracture (should always stabilize PRIOR to radiation)
Lifespan prognosis of achondroplasia and Osteogenesis imperfecta
Achondro = normal BBD = shortened
Both are AD disorders
Amino acid missing in osteogenesis imperfecta
Lacking glycine in collagen triple helix
