Musculoskeletal Fundamentals and Fracture Management Flashcards

Comprehensive vocabulary flashcards covering biomechanics, fracture classification, healing biology, surgical implants, and complications based on musculoskeletal fundamentals.

Anisotropic material

A material, such as bone, in which mechanical properties like strength and stiffness are dependent on the direction of loading.

Cortical bone

A macroscopic bone structure characterized by a porosity of $5\% - 30\%$, typically found in the diaphysis of long bones.

Cancellous bone

A macroscopic bone structure characterized by a porosity of $30\% - 90\%$, often found in the metaphysis and epiphysis.

Elastic deformation

The temporary change in shape of a bone subjected to increased loads where it returns to its original form once the load is removed.

Plastic deformation

The permanent change in shape or structural failure of a bone when subjected to loads exceeding its elastic limit.

Bending force

A force applied perpendicular to the longitudinal axis, causing tensile stress on the convex surface and compressive stress on the concave surface.

Torsional force

A rotational force or moment applied to a long bone that results in a spiral fracture around the circumference.

Axial tensile force

A traction force applied to the bone, typically resulting in an avulsion fracture where a tendon or ligament is attached.

Stable fracture

A fracture where bone fragments interlock and resist shortening forces, such as greenstick or transverse fractures.

Unstable fracture

A fracture where fragments do not interlock and slide out of position, requiring internal or external stabilization.

Indirect (Secondary) bone healing

Healing of unstable fractures characterized by the formation of an intermediate callus, progressing through Inflammation, Repair, and Remodeling phases.

Strain tolerance of bone

The maximum deformation a tissue can withstand before failure, which is strictly less than $2\%$ for bone.

Wolf’s Law

A principle stating that bone adaptively remodels based on stress; positive piezo-electrical currents ($20\,\text{mAmp}$) stimulate osteoclastic activity, while negative currents stimulate osteoblastic activity.

Primary (Direct) bone healing

The direct formation of lamellar bone without intermediary fibrous or fibrocartilaginous tissue, requiring precise anatomical reduction and rigid fixation.

Cutting cones

Groups of osteoclasts at the spearhead followed by osteoblasts that advance longitudinally at $50 - 80\,\mu\text{m/day}$ across a fracture line in contact primary healing.

Extraosseous blood supply

A temporary blood supply derived from surrounding soft tissues that furnishes blood to detached fragments and developing periosteal callus.

Tension surface of the femur

The craniolateral surface of the femur, which is the specific side where fracture treatment must resist tension to prevent gap widening.

DCP (Dynamic Compression Plate)

A bone plate system where screws are placed eccentrically in holes to force bone fragments toward one another, causing compression of the fracture gap.

Neutralization plate

A plate mode used to splint bone and neutralize shearing, bending, and rotational forces on fracture lines already compressed by lag screws or cerclage wires.

Buttress plate

A plate mode that maintains axial alignment and carries the entire load when the underlying bone cannot share the weight, as in highly comminuted fractures.

Cerclage wire principles

Applied in oblique fractures where the fracture length is $2.5 - 3$ times the diameter of the bone; must be placed perpendicular to the long axis and used in pairs.

Monteggia fracture

A fracture of the proximal third of the ulnar diaphysis combined with cranial dislocation of the head of the radius.

Sequestrum

A piece of dead, necrotic cortical bone that forms during osteomyelitis and floating loosely within cellular debris.

Involucrum

A layer of new skin or reactive periosteal bone that builds up around a sequestrum during chronic osteomyelitis.

Cloaca

An opening or hole in the involucrum through which infected exudate and debris can escape from the bone to surrounding tissues.

Hypertrophic nonunion

A viable nonunion characterized by excessive 'elephant’s foot' callus formation due to instability and continuous motion at the fracture site.

Atrophic nonunion

A non-viable nonunion characterized by a lack of callus, avascularity, and loss of weight-bearing activity, leading to bone atrophy.

Osteoinduction

The process by which bone morphogenetic protein (BMP) recruits multipotential osteoprogenitor cells to differentiate into osteoblasts.

Osteoconduction

The process where a bone graft provides a physical scaffold for new capillary ingrowth and the deposition of host bone.

Creeping substitution

The process in cortical bone grafting where the transplant is gradually resorbed by osteoclasts and replaced by new host bone.

Salter-Harris classification

A system used to categorize fractures involving the growth plate (physis) in immature animals, ranging from Grade I to V.

Floating acetabulum

A condition resulting from simultaneous fractures of the ilium, ischium, and pubis, leading to catastrophic hip joint instability.

Plate-Rod technique

The combination of a bone plate and an intramedullary pin (filling $30\% - 40\%$ of the canal) to increase bending strength and protection of the plate.

Type II External Skeletal Fixator

A bilateral biplanar configuration consisting of two connecting bars on either side of the limb, providing stronger stabilization for comminuted fractures.

Distraction osteogenesis (Callotasis)

The gradual distraction of a soft callus at a rate of approximately $1\,\text{mm/day}$ to increase bone length or correct deformities.