The most widely used bedside test for femoral retroversion is Craig’s test (also called the Trochanteric Prominence Angle Test), performed with you lying face-down while a clinician rotates your hip and measures the angle of your shin relative to vertical. But research consistently shows this physical exam has limited accuracy when compared against imaging, and a definitive diagnosis almost always requires a CT or MRI scan. Understanding what each test actually measures and where each one falls short can save you months of misdiagnosis or unnecessary worry.
What Femoral Retroversion Actually Means
Your femur has a built-in twist. The ball at the top (the femoral head) doesn’t point straight sideways; it angles forward relative to the knee. This twist is called femoral version, and it’s measured as the angle between the axis of the femoral neck and a reference line at the knee (the transcondylar or posterior condylar axis).1PubMed Central. Isolated changes in femoral version do not alter intra-articular contact mechanics in cadaveric hips In most adults, this angle sits somewhere around 10 to 15 degrees of forward twist, called anteversion. When the angle is abnormally low or negative, the femoral neck effectively points backward relative to the knee. That’s retroversion.
Femoral version isn’t fixed from birth. During fetal development the angle increases substantially, then gradually decreases through childhood and adolescence until skeletal maturity.2PubMed Central. Femoral anteversion: significance and measurement Some people’s version simply decreases more than average, landing them in the retroverted range. Others may have femoral retroversion due to developmental hip conditions or skeletal variants. Whatever the cause, the practical consequence is the same: the geometry of the hip joint shifts, changing how the femoral head sits inside the socket during movement.
Craig’s Test and How It Works
Craig’s test is the clinical exam you’re most likely to encounter. You lie prone (face-down) with the test knee bent to 90 degrees. The examiner then rotates your hip alternately into internal and external rotation, feeling for the point where the bony bump on the outside of your hip, the greater trochanter, reaches its most lateral position. At that point, the angle between your shin and a vertical line is read as a proxy for your femoral version angle.3PubMed Central. Clinical Tests to Determine Femoral Version Category in People with Chronic Hip Joint Pain and Asymptomatic Controls A small angle or a negative angle suggests retroversion; a large angle suggests excessive anteversion.
The appeal of Craig’s test is obvious: it requires no equipment beyond a goniometer, takes a couple of minutes, and can be done in any clinic or treatment room. It gives the examiner a quick directional signal. If you present with out-toeing, limited internal rotation, and anterior hip pain, and Craig’s test points toward low or negative version, the clinician has a reasonable basis to order imaging. As a screening tool, it has some value. As a diagnostic instrument, the picture is less encouraging.
Why Craig’s Test Often Gets It Wrong
The central problem with Craig’s test is that it relies on the examiner accurately palpating the greater trochanter through soft tissue and correctly identifying the point of maximum prominence. Individual differences in muscle mass, body fat, trochanteric shape, and even how relaxed you are on the table all introduce error. Studies comparing Craig’s test against imaging consistently find that the numbers don’t match up well. One study using MRI as the reference standard found only moderate agreement, with a measurement error of about 6 degrees in either direction, enough to miscategorize someone who’s borderline.4PubMed. Concurrent criterion-related validity and reliability of a clinical test to measure femoral anteversion
More recent work has been blunter. A 2024 study using dual-energy X-ray absorptiometry as its comparison method concluded that Craig’s test is not a valid clinical assessment of true femoral version.5PubMed. Dual-Energy X-Ray Absorptiometry Does Not Confirm Validity of the Craig’s Test Separate research has noted that clinicians are broadly aware that goniometer-based physical exam measurements are not interchangeable with the actual torsion angles obtained through imaging.6PubMed Central. Intra- and inter-examiner reliability of goniometer and inclinometer use in Craig’s test That said, the test’s within-examiner repeatability is reasonably good, meaning a single clinician will tend to get similar readings on the same patient over multiple sessions. The problem isn’t consistency; it’s that the number itself may not reflect what’s truly happening at the bone level.
Other Clinical Clues Beyond Craig’s Test
Clinicians rarely rely on Craig’s test alone. A physical exam for suspected femoral retroversion typically includes measuring passive hip rotation in both directions. Someone with retroversion will often show markedly increased external rotation and reduced internal rotation compared to normal values. A computational analysis confirmed this pattern, finding that decreasing femoral version significantly reduces internal rotation and flexion range of motion.7PubMed Central. Poster 214: The Effect of Femoral Retroversion on Hip Range of Motion – A 3D Computational Analysis
Gait observation offers another window. Femoral retroversion tends to produce an out-toeing walking pattern, where the feet angle outward during the stride. Research on young patients with confirmed retroversion found significantly increased hip external rotation and out-toeing compared to controls.8Journal of Pediatric Orthopaedics. Biomechanical Differences in Young Patients With True Femoral Retrotorsion: Correlations Between Gait Deviations, Clinical Measurements, and Imaging Data Interestingly, the same study found that the midpoint of clinical hip rotation range correlated better with actual walking patterns than the imaging-measured torsion angle did. In other words, the way someone moves in the clinic can sometimes tell you more about their functional limitations than the number from a CT scan, even though that scan gives you the anatomical truth.
These patients also demonstrated compensatory knee valgus (a knock-knee tendency during walking) despite showing no structural knee malalignment on imaging, suggesting the body finds creative workarounds for an abnormal femoral twist.9Journal of Pediatric Orthopaedics. Biomechanical Differences in Young Patients With True Femoral Retrotorsion: Correlations Between Gait Deviations, Clinical Measurements, and Imaging Data
CT and MRI as the Definitive Tests
When a clinician needs to know your actual femoral version angle, imaging is the answer. Both CT and MRI scans can provide reliable measurements and are considered the gold standard by orthopedic surgeons.10Journal of Hip Preservation Surgery. Normal range of femoral version for different measurement methods on CT or MRI—scoping review of normal femoral version The basic approach is the same for both: images are captured at the level of the hip (to define the femoral neck axis) and at the level of the knee (to define the condylar axis), and the angle between the two is calculated.
CT has traditionally been the reference standard. It’s fast, widely available, and produces clear bony landmarks. The downside is radiation exposure, which one pediatric study estimated at roughly 4.5 mSv per scan, equivalent to about a year’s worth of natural background radiation.11PubMed Central. Measurement of Femoral Version by MRI is as Reliable and Reproducible as CT in Children and Adolescents with Hip Disorders That’s a meaningful consideration, especially in younger patients who may need serial imaging. MRI avoids this entirely and produces comparable version measurements. For complex deformities requiring three-dimensional analysis, MRI is increasingly preferred because it lets clinicians evaluate soft tissue, cartilage, and labral anatomy simultaneously while skipping the radiation.12PubMed Central. Consistency of 3D femoral torsion measurement from MRI compared to CT gold standard
Imaging Isn’t Foolproof Either
Even with advanced imaging, measurement accuracy depends on how the scan is performed. The position of your leg during a CT scan matters enormously. If the hip is flexed even slightly, the measured torsion angle drops, potentially pushing someone out of the retroverted category on paper when they’re actually in it.13PubMed. Femoral Torsion: Impact of Femur Position on CT and Stereoradiography Measurements This is why standardized positioning protocols, with the patient lying flat, patellae facing up, and feet secured, are critical.
Traditional two-dimensional measurement techniques on CT are especially vulnerable to positioning errors. A study using 3D-printed femur models scanned in various positions found that conventional 2D methods produced average errors above 12 degrees, and in some positions the error exceeded 22 degrees. Three-dimensional reconstruction methods, by contrast, kept the average error to about 2 degrees regardless of position.14PubMed. Accuracy and reliability of 2D and 3D femoral version measurements on CT scans of 3D-printed haptic femur models: which method is most robust to changes in hip position? The takeaway is that not all CT reports are equally trustworthy. If you’ve been told your version angle is borderline or doesn’t match your symptoms, it’s worth asking whether the measurement used 2D or 3D reconstruction and whether positioning was controlled.
What Femoral Retroversion Does to the Hip Joint
Retroversion matters clinically because it changes how the femoral head meets the acetabulum (the hip socket) during everyday movement. When the femoral neck is twisted backward, the front of the femoral head is brought closer to the rim of the socket during hip flexion. This creates a mechanical conflict known as femoroacetabular impingement, specifically a pinching at the front of the joint that limits both flexion and internal rotation.15PubMed Central. Influence of Femoral Version on the Outcomes of Hip Arthroscopic Surgery for Femoroacetabular Impingement or Labral Tears: A Systematic Review and Meta-analysis
The labrum, a ring of cartilage that deepens the hip socket, often takes the brunt. Research has shown that hips with decreased femoral version tend to develop superior labral damage, with a pattern more consistent with impaction-type impingement rather than the inclusion-type tears typically seen with cam-shaped bone bumps.16PubMed Central. What Is the Influence of Femoral Version on Size, Tear Location, and Tear Pattern of the Acetabular Labrum in Patients With FAI? This distinction matters because it influences surgical planning: a labral tear caused by bony geometry won’t be solved by simply repairing the labrum if the underlying version problem remains.
Downstream Effects on the Knee
The hip doesn’t operate in isolation. Because the femur connects the hip to the knee, abnormal version at the top changes the loading environment at the bottom. Simulation research modeling the stance phase of walking found that both retroversion and excessive anteversion increased knee abduction/adduction forces and worsened how loads were distributed across the kneecap joint.17PubMed Central. Patellofemoral joint load and knee abduction/adduction moment are sensitive to variations in version and individual muscle forces The clinical implication is that persistent anterior knee pain or patellofemoral problems in someone with retroversion may not be a knee problem at all. If the rotational alignment upstream is off, the knee is absorbing forces it wasn’t designed for.
Long-Term Risks and Osteoarthritis
A systematic review published in 2025 pulled together preclinical and clinical evidence on femoral retroversion and early hip osteoarthritis. The findings were sobering: computational models showed that progressive retroversion increases impingement risk earlier in the flexion arc, and the distal femur’s groove may not fully compensate for the rotational mismatch, raising the risk of joint degeneration over time. Clinical data from patients with developmental hip dysplasia found that up to about 12% (predominantly female) had retroversion combined with acetabular retroversion, a combination associated with anterior hip pain and degeneration beginning before age 30.18PubMed Central. Association of femoral retroversion and out-toeing gait with development of hip osteoarthritis and treatment: a systematic review Early detection matters here precisely because the degenerative cascade may be happening quietly for years before symptoms become obvious.
When Surgery Enters the Conversation
For many people with femoral retroversion, conservative management through physical therapy, activity modification, and anti-inflammatory measures is sufficient. Surgery becomes relevant when pain and functional limitation persist despite months of conservative care, particularly when imaging confirms that the version angle is driving impingement.
The primary surgical option is a femoral derotation osteotomy (FDO), in which the femur is cut and rotated to correct the twist, then fixed in the new position with hardware. In a series of patients with version below 5 degrees who underwent FDO, the average patient-reported outcome score improved from roughly 43 points to about 71 on a 100-point scale, and 97% reported subjective improvement in pain and satisfaction.19PubMed Central. Outcomes of femoral de-rotation osteotomy for treatment of femoroacetabular impingement in adults with decreased femoral anteversion A matched comparison study found that FDO and hip arthroscopy produced similar score improvements in patients with decreased version, though all FDO patients were satisfied while two in the arthroscopy group were not.20Journal of Hip Preservation Surgery. Femoral de-rotation osteotomy versus hip arthroscopy for management of femoroacetabular impingement in adult patients with decreased femoral anteversion: a matched retrospective cohort study
After FDO in patients with retroversion, gait tends to normalize. One study showed the average foot progression angle dropped from about 8 degrees of out-toeing preoperatively to near zero at follow-up.21Journal of Hip Preservation Surgery. Less in-toeing after femoral derotation osteotomy in adult patients with increased femoral version and posterior hip impingement compared to patients with femoral retroversion FDO is a bigger operation than arthroscopy, with a longer recovery, but for structurally driven impingement it addresses the root cause rather than trimming around it.
Femoral Retroversion in Athletes
Athletes present a particular challenge because they demand more from their hips and tolerate less functional limitation. The concern has been that retroversion might limit surgical outcomes, since the underlying bony geometry persists even after soft-tissue procedures. But a propensity-matched study of elite athletes with retroversion who underwent hip arthroscopy found that about 83% returned to sport, and nearly 87% achieved clinically meaningful improvements in sport-specific hip scores.22PubMed Central. Outcomes and Return-to-Sport Rates for Elite Athletes With Femoral Retroversion Undergoing Hip Arthroscopy: A Propensity-Matched Analysis With Minimum 2-Year Follow-up
Retroversion also appears to influence movement strategy at a neuromuscular level. Research in soccer players found that lower anteversion (meaning more retroversion) was associated with a distinct, bimodal hip adduction torque pattern during kicking, likely representing the nervous system’s adaptation to skeletal constraints rather than a strength deficit.23PubMed. Exploring the associations of femoral neck anteversion and alpha angle with dynamic muscle function patterns in soccer players: a functional principal component analysis Athletes with retroversion aren’t necessarily weaker or less capable; their bodies simply organize movement differently around their anatomy.
An Evolutionary Footnote on Femoral Version
It’s tempting to think of retroversion as purely pathological, but the picture is more nuanced when you zoom out. Among non-human apes, low anteversion or outright retroversion appears to be the norm. This is likely an adaptation for tree climbing, where the ability to grip branches behind the body is advantageous. Most other mammals, including humans, have higher anteversion, meaning the “typical” human twist is actually the derived state rather than some universal default.24Journal of Hip Preservation Surgery. Evolution of the human hip. Part 1: the osseous framework In that light, human femoral retroversion may represent one end of natural variation rather than a clear-cut deformity. Whether it causes problems depends less on the angle itself and more on how that angle interacts with your specific acetabular shape, activity demands, and the rest of your lower-limb alignment.
Population Variation in Hip Shape
Femoral version doesn’t appear to differ meaningfully between racial groups, at least based on available skeletal studies, which found no significant differences in femoral anteversion when comparing Black and white femora.25ScholarlyCommons. Variation in Femoral Anteversion However, hip morphology as a whole does vary. A population-based study found that Chinese hips showed shallower, narrower sockets and different femoral geometry compared to African American and Caucasian groups, differences that may help explain varying rates of hip osteoarthritis across populations.26Osteoarthritis and Cartilage. Differences between race and sex in measures of hip morphology: a population-based comparative study Sex differences in hip shape are also well documented. The point is that femoral version doesn’t exist in isolation; it’s one variable within a larger geometric system. Two people with the same version angle can have very different clinical experiences if their socket depth, head size, or pelvic tilt differ.