7.2 Posture and Gait Assessment
Key Takeaways
- Posture and gait assessment accounts for roughly 10% of the Neuromusculoskeletal Diagnosis domain on Part II.
- The lateral plumb line should pass through the external auditory meatus, cervical bodies, acromion, lumbar bodies, greater trochanter, and slightly anterior to the knee and lateral malleolus.
- Trendelenburg sign reflects weakness of the stance-side gluteus medius, with the pelvis dropping on the non-weight-bearing side.
- Adam's forward bend test detects axial rotation (rib hump) that distinguishes structural scoliosis from postural asymmetry.
- Antalgic gait shortens stance phase on the painful limb; sensory ataxia worsens with eyes closed (positive Romberg), while cerebellar ataxia does not.
7.2 Posture and Gait Assessment
Quick Answer: Posture and gait assessment represents approximately 10% of the Neuromusculoskeletal Diagnosis domain on NBCE Part II. These items present observed alignment or walking deviations and ask you to identify the underlying muscular, structural, or neurological cause — or to predict which orthopedic test should follow. Static posture uses plumb-line landmarks; dynamic gait analysis distinguishes antalgic, Trendelenburg, and ataxic patterns; scoliosis screening relies on the Adam's forward bend test for rotational rib humps.
Why Posture and Gait Matter on Part II
Posture and gait are the first objective data gathered in any NMS examination. Part II vignettes often describe a standing or walking observation without giving you palpation or orthopedic test results, then ask: What muscle is weak? What condition does this gait pattern suggest? What test should be performed next? Because these findings are observational, they test whether you can translate visual biomechanical clues into anatomical and pathological reasoning.
Static Posture Assessment
Static posture is evaluated with the patient standing relaxed in anatomical position, viewed from anterior, posterior, and lateral perspectives, ideally against a plumb line or posture grid.
Lateral Plumb-Line Landmarks
The plumb line should pass through:
- External auditory meatus
- Bodies of the cervical vertebrae
- Tip of the shoulder (acromion)
- Midpoint of the trunk through lumbar vertebral bodies
- Greater trochanter of the femur
- Slightly anterior to the midline of the knee
- Slightly anterior to the lateral malleolus
Deviations from this alignment identify common postural distortions:
| Finding | Description | Common Cause |
|---|---|---|
| Forward head posture | Ear anterior to plumb line | Upper crossed syndrome, prolonged flexed postures, weak deep neck flexors |
| Increased thoracic kyphosis | Exaggerated posterior thoracic curve | Weak thoracic extensors, tight pectorals, Scheuermann's disease, osteoporotic wedge fractures |
| Increased lumbar lordosis | Exaggerated anterior lumbar curve | Anterior pelvic tilt, tight hip flexors, weak abdominals and glutes |
| Flat back | Reduced lumbar lordosis | Posterior pelvic tilt, tight hamstrings, ankylosing spondylitis |
| Swayback | Hips forward, thorax posterior, increased thoracic kyphosis with relatively normal lordosis | Hip flexor imbalance, habitual standing posture |
| Pelvic obliquity | One iliac crest higher than the other | Leg-length inequality, scoliosis, unilateral muscle contracture |
Anterior and Posterior View Landmarks
Landmarks that should be level and symmetrical include: eyes, ear lobes, acromion processes, nipple line, iliac crests, gluteal folds, popliteal creases, and medial malleoli. Asymmetry is documented and correlated with further testing — it is not diagnosed from observation alone.
Upper crossed syndrome (Janda) describes the common pattern of forward head, increased cervical lordosis, thoracic kyphosis, protracted scapulae, and internally rotated humeri — driven by tight upper trapezius, levator scapulae, pectorals, and suboccipitals paired with weak deep neck flexors, lower trapezius, and serratus anterior.
Lower crossed syndrome pairs anterior pelvic tilt and increased lumbar lordosis with tight hip flexors and erector spinae plus weak abdominals and gluteals.
Dynamic Posture: The Normal Gait Cycle
One gait cycle runs from heel strike of one foot to the next heel strike of the same foot:
- Stance phase (~60%): heel strike → foot flat → midstance → heel-off → toe-off
- Swing phase (~40%): acceleration → mid-swing → deceleration
Normal gait requires coordinated hip, knee, and ankle function, intact proprioception, and adequate hip abductor strength (gluteus medius and minimus) to stabilize the pelvis during single-limb stance.
Antalgic Gait
An antalgic gait is a pain-avoidance pattern. The hallmark is a shortened stance phase on the painful side — the patient minimizes weight-bearing time on the affected limb. Trunk lean toward the painful hip reduces joint reaction force on that side (reducing abductor demand). Antalgic gait is a compensation, not a diagnosis; Part II expects you to recognize the pattern and pursue orthopedic testing to localize the pain generator (hip, knee, ankle, lumbar disc, SI joint).
Part II Clinical Scenario
A 35-year-old runner limps with a noticeably shorter right stance phase and leans the trunk toward the right side while walking. Hip and knee range of motion are full, but Patrick's test reproduces right posterior SI pain. The gait pattern is antalgic — driven by pain avoidance — and the orthopedic finding localizes the source to the sacroiliac joint, not hip osteoarthritis.
Trendelenburg Gait and the Trendelenburg Sign
The Trendelenburg sign tests gluteus medius (hip abductor) strength. The patient stands on one leg; a positive sign occurs when the pelvis on the raised (non-weight-bearing) side drops because the stance-side gluteus medius cannot hold the pelvis level.
Critical exam rule: The pelvis drops opposite the weak abductor, and weakness is named for the stance (weight-bearing) limb.
Trendelenburg gait during walking shows pelvic drop toward the swing-leg side with each step. Patients may compensate with a lurch — leaning the trunk toward the weak stance side to shift the center of gravity medially and reduce abductor demand. This compensated pattern can mask the pelvic drop.
Causes include superior gluteal nerve injury, L5 radiculopathy, hip abductor tear, and developmental dysplasia of the hip.
| Gait Pattern | Key Feature | Underlying Problem |
|---|---|---|
| Antalgic | Shortened stance on painful side | Pain from any musculoskeletal source |
| Trendelenburg | Pelvic drop toward swing side | Stance-side gluteus medius weakness |
| Steppage | Excessive hip/knee flexion to clear foot | Foot drop (L5, peroneal nerve, common fibular neuropathy) |
| Circumduction | Semicircular swing path | Stiff hip or leg-length inequality |
Ataxic Gait Patterns
Cerebellar (staggering) ataxia: wide-based, irregular, lurching gait with poor tandem-walk ability. Worsens roughly equally with eyes open or closed because the deficit is coordination itself.
Sensory ataxia: results from lost proprioceptive input (posterior column disease, peripheral neuropathy, B12 deficiency). Produces a stomping gait with the patient watching the ground. Worsens dramatically with eyes closed — the basis of the Romberg test. A positive Romberg (loss of balance with eyes closed but not open) localizes to dorsal columns or peripheral sensory pathways, not cerebellum.
Part II trap: Do not confuse sensory ataxia with cerebellar ataxia. The eyes-closed worsening is the discriminator.
Scoliosis Screening: Adam's Forward Bend Test
The Adam's forward bend test screens for structural scoliosis. The patient bends forward at the waist with feet together, knees straight, and arms hanging free. The examiner views from behind.
A positive finding is a visible rib hump or paraspinal muscle prominence on one side, caused by axial rotation of vertebral bodies in structural scoliosis. Simple postural asymmetry or leg-length inequality without vertebral rotation does not produce a rib hump.
Quantitative follow-up uses a scoliometer at the apex of the hump; readings of roughly 5–7 degrees or more commonly trigger referral for radiographic Cobb angle measurement.
Additional screening observations: uneven shoulder height, scapular prominence, waist crease asymmetry, and iliac crest height.
Posture-Gait Integration on Part II
Part II items often chain observations: forward head posture plus rounded shoulders plus increased thoracic kyphosis suggests upper crossed syndrome; antalgic gait plus positive Patrick's test suggests SI joint pain; Trendelenburg sign plus L5 radiculopathy history suggests superior gluteal nerve compromise from disc herniation.
When a vignette describes gait or posture alone, ask: Is this a pain-avoidance pattern, a strength deficit, a neurological coordination problem, or a structural deformity? That single classification question narrows the answer choices before you consider individual diagnoses.
A patient stands on the right leg during single-limb stance testing, and the pelvis on the left (non-weight-bearing) side drops. Which structure is most likely weak?
During the Adam's forward bend test, which finding specifically indicates structural scoliosis rather than simple postural asymmetry?
Which feature best distinguishes sensory ataxia from cerebellar ataxia during gait assessment?
A patient walks with a noticeably shortened stance phase on the left leg and leans the trunk toward the left side. What is the most accurate description of this gait pattern?