The femoral neck is the short, slanted stretch of bone just below the ball of your hip, where the top of the thigh bone angles inward to meet the hip socket. Because it sits at an angle and carries your full body weight with every step, it handles more strain than almost any other bone in the body. That load, the thinning that comes with age, and a fragile blood supply are why most people first hear the term after a hip fracture or a bone density scan.
Where the Femoral Neck Sits in Your Hip
The top of the thigh bone has four parts: the femoral head, the neck, and two bony bumps called the greater and lesser trochanters.1PubMed. Anatomy of the femoral neck and head, with comparative data from Caucasians and Hong Kong Chinese The femoral head is the smooth ball that fits into the hip socket in your pelvis. The neck juts out from the shaft toward the socket and holds the ball in place. In adults it meets the shaft at an average angle of about 135 degrees.2PubMed. Anatomy of the femoral neck and head, with comparative data from Caucasians and Hong Kong Chinese
You can get a feel for this on your own body. Put a hand on the bony bump at the side of your hip, which is the greater trochanter. The neck runs inward and upward from there toward your groin. If you picture the thigh bone as a bent elbow pipe, the neck is the short angled section, only a few centimetres long in adults. Most of it sits inside the tough sleeve of tissue around the hip joint.
The neck itself lies deep under muscle, roughly in line with the crease of your groin, so you can’t feel it from outside. A problem in the neck tends to be felt at the front of the hip or in the groin, and sometimes in the thigh or knee, rather than as a spot you can point to on the side. A sore, tender place you can press on at the side is usually a different problem, since the trochanter is a separate part of the bone.
On a hip X-ray, the neck is the narrow waist between the round ball and the wider shaft. Reports may describe fractures as “subcapital” or “intracapsular,” meaning in or near the neck, inside the joint. A bone density report often lists “femoral neck” separately from “total hip.”
Why the Femoral Neck Takes So Much Strain
The two main forces across the hip are body weight and the pull of the muscles on the side of the hip that keep you level when you stand on one leg.3PubMed Central. Femoral neck shaft angle in relation to the location of femoral stress fracture in young military recruits: femoral head versus femoral neck stress fracture Because the neck is angled, these forces bend it like a branch rather than just pressing down on it. The lower edge of the neck is squeezed, while its upper side and the front and back walls are pulled apart.4PubMed Central. Functional morphology of trabecular system in human proximal femur: a perspective from P45 sectional plastination and 3D reconstruction finite element analysis
Every step briefly puts all your weight on one leg, and that is the moment when body weight and the side-hip muscles load the neck together. The muscles must pull hard to keep the pelvis level, and that pull adds to the load beyond body weight alone, multiplying the force on the hip to several times your weight. A healthy bone handles this millions of times a year without trouble.
Inside, the neck is filled with spongy bone arranged in struts that follow the lines of force, wrapped in a hard outer shell.5PubMed Central. The qualitative analysis of trabecular architecture of the proximal femur based on the P45 sectional plastination technique The struts blend tightly with the shell, so the two work as one combined structure.6PubMed. The structure of the femoral neck: A physical dissection with emphasis on the internal trabecular system Near the ball the spongy bone carries most of the load, and toward the shaft the outer shell takes over, carrying up to about 88% when standing.7PubMed. Cortical and trabecular load sharing in the human femoral neck Strength depends on bone density, the neck’s shape, and the thickness of that shell.8PubMed. Biomechanics of Femoral Neck Fractures and Implications for Fixation
Despite this design, the neck is the weak link. It is the narrowest point between the large ball and the thick shaft, and bending loads concentrate where bone is narrowest. When the shell thins, the neck loses the part that carries most of its load.
Shape matters too. A neck angle lower than normal raises stress on the neck itself.9PubMed Central. Femoral neck shaft angle in relation to the location of femoral stress fracture in young military recruits: femoral head versus femoral neck stress fracture A steeper angle moves more stress onto the ball of the hip instead.10PubMed Central. Femoral neck shaft angle in relation to the location of femoral stress fracture in young military recruits: femoral head versus femoral neck stress fracture Body shape plays a part in falls as well: people with hip fractures tend to have a longer lever from the neck to the side of the hip, which raises the force when they fall sideways.11PubMed. Women and men with hip fractures have a longer femoral neck moment arm and greater impact load in a sideways fall
How Aging Weakens the Femoral Neck
Bone loss tends to speed up around menopause. After 65, women lose roughly 0.8% of femoral neck bone density each year.12PubMed. Femoral bone loss progresses with age: a longitudinal study in women over age 65 Over 25 years after menopause, the loss averages about 10%.13PubMed Central. Characteristics of Long‐Term Femoral Neck Bone Loss in Postmenopausal Women: A 25‐Year Follow‐Up Because bone loss doesn’t hurt, a person can lose a meaningful share of neck density and feel completely normal. Loss tends to speed up around menopause.
The structure changes, not just the density. From middle age to old age the outer shell thins by 10 to 15% and its pores almost double.14PubMed. Age- and gender-dependent changes in three-dimensional microstructure of cortical and trabecular bone at the human femoral neck The spongy inner bone loses about a fifth of its volume as struts thin and disconnect.15PubMed. Age- and gender-dependent changes in three-dimensional microstructure of cortical and trabecular bone at the human femoral neck
Men’s femoral necks widen slightly with age, which helps keep them stiff.16PubMed. Sex differences in geometry of the femoral neck with aging: a structural analysis of bone mineral data Women’s do not, so stress in their femoral necks rises about three times faster per decade than men’s.17PubMed. Sex differences in geometry of the femoral neck with aging: a structural analysis of bone mineral data Adjusted for size, men’s femoral necks are about 46% stronger in bending than women’s.18PubMed Central. Effects of Age and Sex on the Strength and Cortical Thickness of the Femoral Neck
A fall that a younger person would shrug off can break a thinned neck. Many of these fractures happen in a simple fall from standing, not a dramatic accident. The first sign for many people is the fracture itself, which is why scans are used to catch the loss earlier in people whose age or history raises their risk.
What Happens When the Femoral Neck Breaks
In older adults, falls to the side or forward carry about four times the hip fracture risk of falls backward or straight down.19PubMed Central. The Effect of Fall Biomechanics on Risk for Hip Fracture in Older Adults: A Cohort Study of Video‐Captured Falls in Long‐Term Care Landing directly on the side of the hip raises risk about fivefold compared with other landings.20PubMed Central. The Effect of Fall Biomechanics on Risk for Hip Fracture in Older Adults: A Cohort Study of Video‐Captured Falls in Long‐Term Care
Signs after a fall include groin or hip pain and trouble putting weight on the leg. The injured leg may look shorter and turned outward. Some breaks where the pieces haven’t shifted still allow walking, so hip or groin pain after a fall needs an X-ray. A person with groin or hip pain who can’t stand on the leg should be treated as having a possible fracture until an X-ray says otherwise. Moving them can shift the broken pieces and damage the blood supply, so keep them still and warm and call for emergency help. Don’t offer food or drink, in case surgery is needed soon, and tell the paramedics about any blood thinners the person takes.
The blood supply is what makes this break so serious. Blood reaches the ball of the hip mainly through small vessels that run along the outside of the neck inside the joint capsule.21International Journal of Cadaveric Studies and Anatomical Variations. Vascular Anatomy of the Proximal Femur and the Risk of Avascular Osteonecrosis When the broken pieces shift, they can tear these vessels.22International Journal of Cadaveric Studies and Anatomical Variations. Vascular Anatomy of the Proximal Femur and the Risk of Avascular Osteonecrosis Without blood, the bone of the ball can die, a condition doctors call avascular necrosis.23PubMed Central. Avascular Necrosis of Femoral Head—Overview and Current State of the Art That can lead to collapse, arthritis and stiffness in the hip later.24PubMed Central. Avascular Necrosis of Femoral Head—Overview and Current State of the Art
Doctors mainly sort these fractures as non-displaced, with the pieces still lined up, or displaced, with the pieces shifted.25PubMed. The reliability of a simplified Garden classification for intracapsular hip fractures After screw repair, about 6% of non-displaced breaks lead to bone death and 18% fail to heal.26PubMed. Avascular necrosis and nonunion after osteosynthesis of femoral neck fractures: effect of fracture displacement and time to surgery For displaced breaks those rates rise to about 23% and 38%.27PubMed. Avascular necrosis and nonunion after osteosynthesis of femoral neck fractures: effect of fracture displacement and time to surgery
For older adults with a displaced break, a total hip replacement led to repeat surgery in about 4% of patients over four years, versus 47% with screws.28PubMed. Comparison of internal fixation with total hip replacement for displaced femoral neck fractures. Randomized, controlled trial performed at four years Hip function and quality of life were better after replacement.29PubMed. Comparison of internal fixation with total hip replacement for displaced femoral neck fractures. Randomized, controlled trial performed at four years Even in people aged 40 to 59, screw repair carries higher odds of repeat surgery than replacement.30PubMed Central. Fixation vs Arthroplasty for Femoral Neck Fracture in Patients Aged 40-59 Years: A Propensity-Score-Matched Analysis
Why Bone Density Scans Measure the Femoral Neck
A DXA scan is a low-dose X-ray that measures how much mineral is packed into the bone at the hip, spine or forearm.31Cleveland Clinic. DXA and Clinical Challenges of Fracture Risk Assessment in Primary Care The result is converted into a T-score, which shows how far your density is from the average of healthy young adults.32Scientific Reports. BMD T-Score (Left Femoral Neck) Test | Instalab
- -1.0 or higher: normal bone density
- Between -1.0 and -2.5: low bone density, sometimes called osteopenia
- -2.5 or lower: osteoporosis
The neck is measured because it is where the most serious hip fractures happen, so its density bears directly on the risk the scan is trying to estimate. Measuring at the hip as well as the spine gives a fuller picture, since bone loss can differ from one site to another. A spine reading can be inflated by arthritis or compressed bones in older adults, which is one reason the hip is often more reliable in later life. Reports often list femoral neck, total hip and spine separately, and doctors usually go by the lowest score among them.
A low score signals risk, not certainty. It’s reasonable to ask whether treatment or a repeat scan is recommended, and when.
How to Protect Your Femoral Neck
Walking loads the femoral neck mainly through the muscle at the front of the hip.33PubMed. Mechanical Loading of the Femoral Neck in Human Locomotion Climbing stairs and jumping bring in the buttock muscles and harder impact with the ground, which strain the neck more.34PubMed. Mechanical Loading of the Femoral Neck in Human Locomotion These higher-impact moves are a target for keeping the neck strong. If it is safe for you, add stairs, step-ups or small hops alongside walking, and ask a doctor first if you already have osteoporosis.
Build up gradually. Bone responds to loads it is not used to, so a slow increase gives the neck time to adapt. Someone with low bone density should start with a physical therapist’s or doctor’s advice rather than jumping, since a hard landing can itself cause harm.
Because sideways falls onto the hip are the most dangerous, preventing falls protects the femoral neck directly. That means removing loose rugs and clutter from walkways, adding night lights and bathroom grab bars, reviewing medicines that cause dizziness with a doctor, and checking vision and footwear.
In nursing homes, padded hip protectors prevent about 11 hip fractures per 1,000 people who get them.35PubMed Central. Hip protectors for preventing hip fractures in older people For older people living at home, they show little or no benefit.36PubMed Central. Hip protectors for preventing hip fractures in older people
The basics help too. Get enough calcium and vitamin D through diet or supplements if advised, avoid smoking, and limit alcohol, both of which are linked with bone loss. If your T-score is low, ask about osteoporosis medicine.
Other Problems That Affect the Femoral Neck
Repeated pounding can cause tiny cracks in the femoral neck, especially in runners and military recruits.37SICOT-J. Femoral neck stress fracture in a young female recruit: case report Women and people with low starting fitness are at higher risk.38PubMed Central. Femoral Neck Stress Fractures in Sport: A Current Concepts Review The pain usually starts as a dull ache in the groin during running, appears earlier in each run, and eventually shows up with walking or at night. Hopping on the painful leg or pressing at the groin may hurt, but that is only a clue; imaging is needed to confirm it, and an X-ray can be normal early on, so an MRI may be needed. Groin pain that worsens with running and doesn’t settle deserves a prompt medical check, since these cracks can progress.39SICOT-J. Femoral neck stress fracture in a young female recruit: case report
Some people have a bony bump where the ball meets the neck.40PubMed. Cam morphology and the development of femoroacetabular impingement syndrome and hip osteoarthritis It is found in about 15 to 25% of people without symptoms, mostly men.41PubMed. Origin of Cam Morphology in Femoroacetabular Impingement The bump can pinch against the socket rim when bending and turning the hip inward.42PubMed Central. Femoroacetabular impingement: A classic case of cam-type impingement in a 21-year-old soldier In some people, over time, this can damage cartilage and lead to hip arthritis.43PubMed. Cam morphology and the development of femoroacetabular impingement syndrome and hip osteoarthritis It typically affects young active adults with groin pain on deep bending or sitting.
In growing children, the ball of the hip can slip off the neck at the growth plate, called slipped capital femoral epiphysis.44PubMed. A damage model for the growth plate: application to the prediction of slipped capital epiphysis It is usually fixed with a screw to stop further slipping.45Journal of Southeast Asian Orthopaedics. Femoral Neck Growth and Remodeling After Screw Removal Following Slipped Capital Femoral Epiphysis Fixation can sometimes affect how the neck grows, including shortening it.46PubMed. Osteosynthesis with the hook-pin in slipped capital femoral epiphysis Teenagers with this often have a limp and knee or thigh pain, because hip problems can refer pain down to the knee. A limping teen with knee pain should have the hip examined, and early treatment of a slip gives better results.