Arab Board Orthopedic Surgery Final key terms

The principle that bone remodels along the lines of mechanical stress it experiences, adding mass where loads are high and resorbing where they are low. It explains adaptive cortical thickening and stress shielding after implants.

Loss of bone density caused by an implant carrying load that bone would normally bear. The unloaded bone resorbs, weakening fixation and raising later fracture risk around stiff stems and plates.

The property of a graft or scaffold that lets host bone grow into it along its surface, acting as a trellis. It does not itself supply living cells or induce new bone formation.

The ability of a material to recruit undifferentiated host cells and stimulate them to become bone-forming cells. Demineralized bone matrix and bone morphogenetic proteins act mainly through this mechanism.

The contribution of living, viable cells within a graft that survive transplantation and directly lay down new bone. Fresh autograft has this property; processed allograft and most substitutes do not.

Formation of mature bone in soft tissues outside the skeleton, typically after trauma, burns, brain injury or hip surgery. It causes stiffness and pain and is prevented with prophylactic NSAIDs or low-dose radiotherapy.

Raised pressure within a closed fascial compartment that compromises capillary perfusion and threatens muscle and nerve viability. It presents with pain out of proportion, pain on passive stretch, and is treated by urgent fasciotomy.

Permanent ischemic necrosis and fibrosis of forearm flexor muscles following untreated compartment syndrome. The resulting contracture leaves a deformed, functionless hand with fixed wrist and finger flexion.

A staged strategy in severely injured patients that uses temporary stabilization such as external fixation to limit surgical insult, then performs definitive fixation once physiology has recovered. It aims to avoid the lethal triad of hypothermia, acidosis and coagulopathy.

A systemic reaction to marrow fat entering the circulation after long-bone fractures, producing hypoxia, petechiae and confusion typically one to three days after injury. Treatment is supportive with oxygen and early fracture stabilization.

Failure of a fracture to heal within the expected time with no further healing potential, showing a persistent gap, sclerosis or hypertrophic callus. It usually requires surgical intervention such as revision fixation and bone grafting.

Slower than expected healing of a fracture that has not yet reached the point of established nonunion. Continued observation with correction of mechanical or biological deficiencies may still allow union.

Failure of an implant's fixation without infection, driven by particle wear debris, macrophage-mediated osteolysis and micromotion. It causes progressive radiolucent lines and component migration, and is the leading long-term reason for revision arthroplasty.

Infection involving a joint replacement and its surrounding tissues, often from biofilm-forming organisms on the implant surface. Diagnosis uses joint aspiration, inflammatory markers and cultures; treatment ranges from debridement to staged exchange arthroplasty.

A structured community of bacteria adhering to a surface and embedded in a self-produced matrix. It shields organisms from antibiotics and host defenses, explaining the chronicity of implant-associated infections.

A fracture occurring near or around an orthopedic implant, usually after low-energy trauma in bone weakened by the implant or osteoporosis. Management depends on implant stability and bone stock, using fixation or revision.

The layer of bone cement between an implant and bone that provides fixation by interlocking with bone trabeculae. Its quality and completeness predict durability of cemented arthroplasty.

Autologous, allogeneic or synthetic material placed to fill defects and promote healing through osteoconduction, osteoinduction or living cells. Autograft remains the reference standard for its biological and structural properties.

A skeletal disorder of reduced bone mass and deteriorated microarchitecture causing fragility fractures. It is defined by low bone mineral density on dual-energy x-ray absorptiometry and managed with calcium, vitamin D and antiresorptive or anabolic drugs.

A fracture caused by a fall from standing height or less, or from minimal trauma, in bone weakened by osteoporosis. It defines the clinical threshold for investigating and treating underlying bone disease.

A primary malignant bone tumor producing osteoid, most often arising in the metaphysis of long bones in adolescents. Treatment combines neoadjuvant chemotherapy with wide surgical resection and reconstruction.

The distance and tissue plane between a resected tumor and the cut edge of the specimen. An intralesional margin passes through tumor, marginal passes through reactive tissue, and wide passes through normal tissue beyond the reactive zone.

Progressive fibrosis of the palmar fascia causing painless nodules and cords that tether the fingers into flexion, most often the ring and little fingers. Treatment includes needle fasciotomy, collagenase injection or surgical fasciectomy.

Compression of the median nerve within the carpal tunnel causing nocturnal numbness, thenar weakness and sensory loss in the median distribution. It is confirmed by nerve conduction studies and treated by release when conservative measures fail.

A predictable pattern of wrist arthritis that follows an unhealed scaphoid fracture, beginning between the scaphoid and radius and progressing to the capitate and lunate. Treatment depends on stage and may require reconstruction or salvage procedures.

Surgical replacement of a torn anterior cruciate ligament with a tendon graft to restore knee stability and reduce giving-way. Rehabilitation focuses on restoring quadriceps strength, proprioception and safe return to sport.

The position and orientation of bone tunnels drilled for ligament reconstruction, which determine graft length, tension and knee kinematics. Non-anatomic placement is a common cause of recurrent instability after reconstruction.

Avulsion or radial tear at the attachment of the meniscal horn, which abolishes hoop stress and effectively removes the meniscus. It accelerates cartilage loss and is treated by repair when feasible.

Suturing a torn meniscus to preserve its load-sharing and shock-absorbing function, most successful in peripheral vascularized tears. Preservation is preferred over excision because removal accelerates osteoarthritis.

A spectrum of abnormal hip development ranging from shallow acetabulum to frank dislocation, detected by screening examination and ultrasound in infancy. Early bracing or surgical reduction prevents premature hip arthritis.

A dynamic abduction splint used in infants with developmental dysplasia of the hip to hold the femoral head reduced and stimulate acetabular development. It is most effective when started early and requires close monitoring.

Displacement of the femoral head through the growth plate in older children or adolescents, presenting with hip or referred knee pain and an antalgic gait. It is stabilized with in-situ screw fixation to prevent further slip.

Idiopathic avascular necrosis of the femoral head in children, causing pain, limp and a variable course of fragmentation and reossification. Treatment aims to contain the head within the acetabulum during healing.

Compression of the lumbosacral nerve roots causing saddle anesthesia, bladder and bowel dysfunction and bilateral leg weakness. It is a surgical emergency requiring urgent decompression to prevent permanent deficit.

Narrowing of the spinal canal or neural foramina causing nerve root or cord compression, classically with neurogenic claudication relieved by leaning forward. Treatment ranges from activity modification to surgical decompression.

Progressive destruction of a weight-bearing joint from loss of protective sensation and proprioception, most often the diabetic foot. It causes a warm swollen foot, deformity and ulceration, managed with offloading and sometimes reconstruction.

A break in the skin of the foot in a person with diabetes, driven by neuropathy, ischemia and pressure. Management requires offloading, debridement, infection control and vascular assessment.

The process of giving a patient adequate information about a proposed procedure, its alternatives and risks so they can voluntarily decide. It is a legal and ethical requirement and must be documented before surgery.

A serious, largely preventable patient-safety incident such as wrong-site surgery or a retained surgical item that should not occur. Reporting and system-based prevention, including surgical safety checklists, are standard safeguards.