Fragility fracture of the proximal femur in older adults; surgical repair within 24-48 h and aggressive secondary fracture prevention.
Also known as: hip fracture, femoral neck fracture, intertrochanteric fracture, subtrochanteric fracture, proximal femur fracture
Overview
Fracture of the proximal femur, classified by anatomic location: intracapsular (femoral neck, subcapital) or extracapsular (intertrochanteric, subtrochanteric). Most often a fragility fracture in older adults from a low-energy fall; high-energy fractures occur in younger patients.
Epidemiology
Over 300,000 hip fractures annually in the US. Lifetime risk in white women ~15%. Mortality at one year is ~20-30%; many survivors lose independence. Mean age 80.
Try two board-style Hip Fracture questions
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Question 1MusculoskeletalMedium
An 82-year-old woman with two falls in the past year presents after slipping in her kitchen and landing on her left hip. She reports severe left hip and groin pain and cannot bear weight. On exam the left leg is shortened and externally rotated. Radiographs confirm a displaced femoral neck fracture. Which of the following best explains the mechanism by which her bone failed under this low-energy fall?
AReduced bone density weakening trabecular bone
BExcessive cortical bone deposition and thickening
CRepetitive microtrauma to normal bone
DOsteoblastic sclerotic metastatic bone deposits
EFocal avascular necrosis of the femoral head
Reveal answer & full explanation
Correct answer: A — Reduced bone density weakening trabecular bone
AReduced bone density weakening trabecular bone✓
BExcessive cortical bone deposition and thickening
CRepetitive microtrauma to normal bone
DOsteoblastic sclerotic metastatic bone deposits
EFocal avascular necrosis of the femoral head
Why Reduced bone density weakening trabecular bone is correct
This is a fragility (osteoporotic) hip fracture.
Advanced age, female sex, low bone mineral density, and a history of falls are the dominant risk factors, and the shortened, externally rotated leg with an inability to bear weight is the classic presentation of a femoral neck fracture.
The core mechanism is that osteoporosis lowers bone mineral density and disrupts trabecular microarchitecture, reducing the load the bone can withstand so that it fails under low-energy trauma such as a simple fall.
Reduced bone density with weakened trabecular architecture is the pathophysiologic explanation for a fragility fracture.
Why the others are wrong
Osteoblastic sclerotic metastatic bone deposits — pathologic fractures from metastases (e.g., prostate cancer) are a distinct cause; nothing here suggests malignancy, and osteoporotic bone is diffusely osteopenic rather than sclerotic.
Excessive cortical bone deposition and thickening — this describes disorders like osteopetrosis or Paget disease, the opposite of the reduced bone mass that defines osteoporosis.
Focal avascular necrosis of the femoral head — AVN is a complication that can follow a femoral neck fracture due to disrupted blood supply, but it is not the mechanism by which the bone initially fractured under low load.
Repetitive microtrauma to normal bone — repeated submaximal loading of structurally normal bone produces fatigue-type stress fractures of the femoral neck in young athletes and military recruits, but this fracture followed a single low-energy fall in an elderly woman, the hallmark of a fragility fracture through bone weakened by osteoporosis.
Question 2MusculoskeletalMedium
A 74-year-old woman is seen for a bone-health visit after a ground-level fall last month that left her with a wrist fracture. She lives alone and walks without an assistive device. Her history includes a vertebral compression fracture two years ago, well-controlled hypertension, and a 20-pack-year smoking history that she quit a decade ago. She drinks one glass of wine most evenings. Her body mass index is 23 kg/m2, and she takes no glucocorticoids or sedatives. She is concerned about breaking her hip. Which of the following is the strongest risk factor for hip fracture in this patient?
ALiving alone without help
BPostmenopausal estrogen loss
CModerate daily alcohol use
DPrior fragility fracture
EFormer tobacco use history
Reveal answer & full explanation
Correct answer: D — Prior fragility fracture
ALiving alone without help
BPostmenopausal estrogen loss
CModerate daily alcohol use
DPrior fragility fracture✓
EFormer tobacco use history
Why Prior fragility fracture is correct
A previous low-energy (fragility) fracture is the single strongest clinical predictor of a future hip fracture, independent of bone mineral density. It roughly doubles or more the risk of a subsequent fracture and signals established skeletal fragility.
This patient already has TWO fragility events (a vertebral compression fracture and now a low-energy wrist fracture), which places her at high near-term fracture risk and should trigger osteoporosis pharmacotherapy.
It is a heavily weighted input in the FRAX risk tool and is the dominant driver of her absolute hip-fracture risk here.
Why the others are wrong
Former tobacco use history - Smoking is a genuine risk factor for low bone density and fracture, but its effect is modest and largely attenuated after a decade of cessation, far weaker than a prior fragility fracture.
Living alone without help - Social isolation relates to fall risk and post-fracture outcomes but is a weak, indirect contributor compared with a documented fragility fracture.
Moderate daily alcohol use - Heavy alcohol use (3 or more drinks/day) raises fracture risk, but one drink daily is low-level and contributes minimally relative to her prior fractures.
Postmenopausal estrogen loss - estrogen deficiency drives bone loss after menopause, but it is shared by essentially every woman her age and, unless menopause was premature, is not a separate FRAX input beyond sex and age, whereas her two prior fragility fractures show established skeletal fragility and independently predict hip fracture.
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Prior fragility fracture (vertebral, wrist, proximal humerus) — among the strongest predictors; roughly doubles future hip fracture risk independent of BMD
History of falls, gait/balance impairment, sarcopenia
Chronic glucocorticoids, sedatives, polypharmacy
Vitamin D deficiency
Current smoking, alcohol 3 or more units/day (FRAX inputs)
Cognitive impairment, dementia
Visual impairment
Atypical femoral fracture risk: long-term bisphosphonate or denosumab use, asian ancestry
Pathophysiology
Reduced bone strength (osteoporosis) plus increased fall risk leads to fracture from a low-energy mechanism. The femoral neck is intracapsular — its blood supply via the medial femoral circumflex artery is at high risk of disruption with displaced fractures, leading to osteonecrosis. Intertrochanteric and subtrochanteric fractures occur through cancellous trochanteric bone and heal more reliably but with greater blood loss.
Clinical presentation
Symptoms
Hip, groin, or knee pain after a fall (referred to the knee via obturator nerve — always examine the hip in older adult with knee pain)
Inability to bear weight
Occult fracture: groin pain with normal X-ray and inability to bear weight or perform straight-leg raise
Signs / physical exam
Affected leg shortened and externally rotated (displaced femoral neck or intertrochanteric)
Pain with any hip motion, especially log-roll
Inability to straight-leg raise against gravity
Tenderness over greater trochanter or in groin
Distal neurovascular exam typically intact
Look for cause of fall: arrhythmia, syncope, medication effect, infection, dementia
Differential diagnosis
Pubic ramus fracture — Groin pain after fall; tender pubic ramus; AP and inlet/outlet pelvis radiographs
Greater trochanter contusion or fracture — Lateral hip pain, can bear weight
Acute hip OA flare — Chronic pain pattern, X-ray with arthritic change
Occult or stress fracture — Pain without obvious X-ray fracture; MRI sensitive — strongly consider when X-ray negative but exam positive
Pathologic fracture — Known malignancy, atraumatic onset, lytic lesion on imaging
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