Clinical Examination of Hand- Ulnar Nerve — OrthopaedicPrinciples.com

Courtesy: Dr Terrence Jose Jerome, FRCS. Editor, Journal of Hand and MicroSurgery

Clinical Examination of Ulnar Nerve Palsy / Claw Hand

Overview

The lecture is centered on the clinical examination of ulnar nerve palsy, especially how to:

Identify the cause and level of lesion
Differentiate high vs low ulnar palsy
Distinguish isolated ulnar palsy from combined median–ulnar palsy
Assess intrinsic muscle dysfunction
Decide whether the claw deformity is supple or fixed
Use clinical findings to guide reconstructive treatment

emphasizes a standard clinical sequence:

History – Inspection – Palpation – Motor examination – Sensory examination – Special tests – Investigations – Differential diagnosis.

Etiology

Important causes mentioned in the lecture include:

Acute laceration/cut injury
Road traffic injury
Injury associated with fractures
Delayed/tardy ulnar palsy
Long-standing lateral condyle nonunion with cubitus valgus
Hansen disease
Compression neuropathy
Brachial plexus lesions involving C8–T1
Thoracic outlet syndrome
Hereditary motor-sensory disorders such as Charcot–Marie–Tooth disease

The history is important for deciding whether the lesion is:

Acute
Old/chronic
Traumatic
Compressive
Infective
Neurological/systemic

High vs Low Ulnar Nerve Palsy

uses the relationship of the lesion to the motor branch to flexor carpi ulnaris (FCU) as a major clinical discriminator.

High Ulnar Palsy

Lesion:

Proximal to the origin of the FCU branch

Therefore proximal ulnar-innervated muscles may be affected.

Low Ulnar Palsy

Lesion:

From below the FCU branch toward the distal forearm/wrist

specifically highlights this distinction as a common viva question.

Viva Pearl

Weak FCU – think high ulnar palsy

Intact FCU – favors low ulnar palsy

later reiterates that FCU is a useful quick discriminator between the two levels.

Causes of Ulnar Nerve Compression

Potential sites/causes discussed include:

Around the elbow

Proximal structures around the cubital tunnel
Between the two heads of FCU
Fascial structures around FDP/FCU region

Wrist / Guyon canal

Compression can occur due to:

AV malformation
Trauma
Ganglion
Small tumor

The transcript emphasizes that the entire possible zone of compression should be considered rather than assuming one isolated point.

Examine From Proximal to Distal

The lecturer recommends examination from:

Shoulder / brachial plexus – arm – elbow – forearm – hand

This helps rule out:

Lower brachial plexus palsy
Thoracic outlet syndrome
Proximal ulnar lesion
Cubital tunnel lesion
Distal ulnar lesion

Also assess the carrying angle, particularly when tardy ulnar palsy associated with old fracture/cubitus valgus is suspected.

Inspection in Ulnar Palsy

Classical Clawing

The characteristic posture is:

MCP hyperextension
IP joint flexion

This is most obvious in the ulnar digits in isolated ulnar palsy.

Other Inspection Findings

Look for:

Hypothenar wasting
Interosseous wasting
Flattening of the ulnar side of palm
Dry, shiny skin
Loss of normal pulp ridges
Trophic ulcers
Established contractures
Finger shortening/absorption in severe chronic disease such as Hansen disease

In combined median + ulnar palsy, both thenar and hypothenar regions may be wasted and the whole palm may appear flattened.

Interosseous Muscle Wasting

The dorsal interossei lie between the metacarpals, so dorsal wasting produces visible hollowing between the metacarpals.

reinforces the classic mnemonic:

DAB = Dorsal interossei ABduct

PAD = Palmar interossei ADduct

Froment Sign

This is one of the most important tests for ulnar palsy.

Technique

Ask the patient to hold a card or paper between the thumb and index finger.

Normal

Thumb adduction is maintained using the:

Adductor pollicis

Positive Froment Sign

Because adductor pollicis is weak, the patient compensates using:

Flexor pollicis longus

This produces:

Flexion of the thumb IP joint

Mechanism

Adductor pollicis weak ? FPL substitutes – thumb IP flexes

Viva Answer

Froment sign is flexion of the thumb IP joint during key pinch due to FPL compensation for weak adductor pollicis in ulnar nerve palsy.

Thumb Examination and Median Nerve Function

warns against diagnosing isolated ulnar palsy without checking median nerve function.

Assess:

Flexor pollicis brevis
Abductor pollicis brevis
Flexor pollicis longus
Adductor pollicis

The lecture notes that flexor pollicis brevis has dual innervation, so its weakness may not be complete in isolated ulnar palsy.

The patient may compensate during pinch by:

Hyperextending the MCP joint
Flexing the IP joint with FPL

This produces an abnormal pulp-pinch mechanism.

Isolated Ulnar vs Combined Median–Ulnar Palsy

A key part of the examination is determining whether median nerve function is preserved.

Isolated Ulnar Palsy

Ulnar intrinsic muscles weak
Median-innervated thumb function remains relatively preserved
First and second lumbricals remain functional
Clawing is more prominent in ring and little fingers

Combined Median + Ulnar Palsy

Thenar as well as ulnar intrinsic function is compromised
All lumbricals may be affected
More extensive clawing can occur
Pinch becomes severely impaired

The transcript repeatedly emphasizes checking the median nerve before calling the lesion an isolated ulnar palsy.

Interosseous Muscle Tests

The lecturer groups ulnar examination by function rather than simply memorizing named tests.

For the interossei, ask the patient to:

Abduct fingers
Adduct fingers
Move the middle finger side-to-side
Cross one finger over another
Hold a card between adjacent fingers

These movements assess the:

Dorsal interossei
Palmar interossei

Card Test

A card is placed between adjacent fingers and the patient is asked to hold it while the examiner pulls.

The important precaution is:

Keep the fingers extended

Otherwise the patient may cheat by flexing the fingers with the long flexors instead of using the interossei.

The lecturer explicitly calls this a trick movement when the patient grips the card using finger flexion.

Wartenberg Sign

The transcript describes inability to bring the little finger back into adduction.

The little finger remains abducted because of imbalance between:

Extensor digiti minimi
Weak ulnar-innervated intrinsic adductors

Thus:

Persistent abduction of the little finger = Wartenberg sign

Hypothenar Wasting and Loss of Palmar Cup

emphasizes the functional importance of the cup shape of the hand.

With ulnar intrinsic/hypothenar wasting:

The ulnar palm becomes flattened
The normal metacarpal arch/cupping is lost
Holding larger objects becomes difficult

Mechanism of Claw Hand

Normal intrinsic muscles and lumbricals perform:

MCP flexion + IP extension

In ulnar palsy, the ulnar lumbricals and interossei are paralyzed.

Therefore:

MCP flexion force is lost
Long extensors act unopposed – MCP hyperextension
Long flexors act unopposed – IP flexion

This produces the classical claw posture:

MCP hyperextension + PIP/DIP flexion

Isolated vs Complete Claw Hand

Isolated Ulnar Palsy

3rd and 4th lumbricals affected
1st and 2nd lumbricals remain functional because of median nerve supply
Therefore clawing predominantly affects:
- Ring finger
- Little finger

Combined Median + Ulnar Palsy

All lumbricals become dysfunctional.

Therefore:

All four fingers may claw

This is a useful way of differentiating isolated ulnar palsy from combined median-ulnar palsy.

Bouvier Test

One of the most clinically important tests in claw hand.

Purpose

Determines whether the IP joint extension deficit is:

Correctable when MCP hyperextension is blocked
Therefore whether the deformity is supple

Technique

Observe clawing with MCP hyperextension.
Examiner blocks/prevents MCP hyperextension and places the MCP joint into flexion.
Ask the patient to extend the IP joints.

Positive Bouvier Test

If the patient can now fully extend the IP joints:

Positive Bouvier test

This means the deformity is relatively supple and correction focused on restoring MCP flexion may be adequate.

Exam Pearl

Block MCP hyperextension – IP extension becomes normal = positive Bouvier test.

Bouvier Test and Surgical Planning

this examination helps determine the reconstructive strategy.

If IP joints fully extend after MCP block

The problem is predominantly MCP hyperextension.

gives examples of MCP-focused procedures such as:

Lasso procedure
Zancolli-type procedure

If some correctable IP extensor lag remains

A more dynamic reconstruction may be required to:

Flex the MCP joint
Extend the IP joints

tendon-transfer concepts using wrist extensor or other donor tendons connected toward the lateral bands.

Fixed Claw Deformity

In long-standing disease, secondary structural changes may occur:

Shortening of long flexors
PIP stiffness
Volar plate contracture
Lateral-band displacement
Retinacular attenuation

If the finger cannot be passively brought into extension:

The deformity is fixed/contracted rather than supple.

discusses treatment principles including:

Stretching/splinting
Serial correction
Fractional flexor lengthening in selected cases
PIP fusion in severe stiff deformity

Deformity Angle

the deformity angle as the combination of:

MCP hyperextension angle
PIP flexion angle

Therefore:

Deformity angle = MCP hyperextension + PIP flexion

Measured using a goniometer.

Unassisted, Assisted and Contracture Angles

Unassisted Angle

The deformity measured without examiner correction.

Assisted Angle

The examiner corrects/blocks the MCP hyperextension and then measures the residual PIP flexion.

Contracture Angle

The remaining deformity despite passive attempted correction.

A residual fixed flexion angle suggests a structural PIP contracture.

Why They Matter

These measurements help determine:

Whether the deformity is supple
Whether there is extensor lag
Whether there is fixed PIP contracture
Whether MCP-only correction is likely to work
Whether additional soft-tissue/tendon procedures are needed

Extrinsic Flexor Examination

The ulnar nerve supplies the FDP to the:

Ring finger
Little finger

Therefore, assess isolated FDP function in these fingers.

High Ulnar Palsy

Because the lesion is proximal:

Ring/little finger FDP may be weak.

Low Ulnar Palsy

These FDP muscles should remain functional.

This is another important discriminator between high and low lesions.

Sensory Examination

The lecture emphasizes:

Light touch/fine touch
Two-point discrimination
Tinel sign
Semmes-Weinstein monofilament testing
Vibratory perception in selected cases

The principal ulnar sensory territory described includes:

Little finger
Ulnar half of ring finger

Dorsal Ulnar Cutaneous Sensation and Lesion Localization

The transcript makes an important localization point.

Check sensation over the dorsoulnar hand/wrist region supplied by the dorsal cutaneous branch.

Proximal/high lesion

The dorsal cutaneous branch may also be involved.

Distal lesion

Dorsal sensation may remain intact.

Therefore:

Preserved dorsoulnar sensation favors a lesion distal to the takeoff of the dorsal cutaneous branch.

The lecturer uses this clinically to help distinguish higher from lower ulnar lesions.

Tinel Sign and Nerve Regeneration

The lecturer recommends testing Tinel from:

Distal toward proximal

In an old injury, a Tinel sign that remains fixed at the lesion without distal progression was interpreted by as evidence of absent progression of regeneration and possible complete injury.

This is a speaker-stated clinical interpretation and should not be treated as an absolute diagnostic rule.

Functional Examination

The lecture repeatedly stresses examining what the patient can actually do.

Assess:

Key pinch
Pulp-to-pulp pinch
Precision grip
Power grip
Finger abduction/adduction
Ability to cup the hand
Ability to hold a ball
Ability to pick up a coin

Loss of intrinsic function leads to:

Weak grip
Poor pinch
Loss of palmar cupping
Difficulty holding larger objects
Difficulty with precision tasks

Ball-Holding Test / Functional Grip

demonstrates that in a normal hand:

MCP flexion begins first, followed by subsequent flexion of the fingers.

In ulnar palsy:

Intrinsic MCP flexion is deficient
IP flexion may occur prematurely through the long flexors
The hand fails to form an effective cup
A ball may slip out of the palm

This provides a functional demonstration of intrinsic muscle loss.

Chronic Claw Hand Changes

Long-standing clawing may lead to:

PIP contracture
Volar plate contracture
Lateral-band displacement toward the volar side
Attenuation of dorsal retinacular structures
Progressive fixed deformity

these secondary changes must be assessed before selecting a tendon transfer.

Do not treat every claw hand with the same procedure.

The exact deformity at the MCP and PIP levels, its duration, suppleness and associated contractures should determine surgery.

Disability vs Impairment

distinguishes:

Impairment

Loss or abnormality of an anatomical structure/body part.

Disability

Inability to perform an activity because of that impairment.

In ulnar palsy, disability may include:

Loss of effective pinch
Weak grip
Inability to adduct/abduct fingers normally
Poor precision handling
Loss of hand cupping

Important Q&A Point — FCU

At the end of the lecture, specifically reiterates:

FCU function is one of the key clinical features for differentiating high from low ulnar palsy.

He also agrees with using a small group of key muscles for quick ulnar evaluation, including:

First dorsal interosseous
Abductor digiti minimi
FCU

also notes that anomalous median-ulnar connections may occasionally alter expected findings, mentioning Martin-Gruber-type anastomosis and other anomalous communications. These are advanced considerations and may explain atypical motor patterns.

Guyon Canal — Motor vs Sensory Pattern

In the discussion, explains that the clinical pattern depends on whether the lesion affects the ulnar nerve:

Before its motor/sensory division
Motor branch
Sensory branch

Thus distal ulnar compression may produce:

Combined motor + sensory deficit
Predominantly motor deficit
Predominantly sensory deficit

depending on the exact level and branch involved.

The detailed zone classification of Guyon canal was not fully taught in this transcript, so it should not be reconstructed beyond what actually states.

High-Yield Examination Table

Finding/Test	What it assesses
FCU power	High vs low ulnar palsy
Ring/little FDP	High vs low lesion
Froment sign	Adductor pollicis weakness
Finger abduction	Dorsal interossei
Finger adduction	Palmar interossei
Card test	Interosseous function
Finger crossing	Intrinsic/interosseous function
Wartenberg sign	Ulnar intrinsic weakness
First dorsal interosseous wasting	Ulnar motor deficit
Hypothenar wasting	Ulnar motor deficit
Bouvier test	Supple vs fixed claw / surgical planning
Deformity angle	Overall claw severity
Assisted angle	Residual deformity after MCP correction
Contracture angle	Fixed IP contracture
Dorsoulnar sensation	Helps localize lesion
Tinel sign	Site/possible regeneration progression
Ball-holding/cupping	Functional intrinsic muscle loss

High vs Low Ulnar Palsy

Feature	High palsy	Low palsy
FCU	Weak	Preserved
Ring/little FDP	May be weak	Preserved
Intrinsic muscles	Weak	Weak
Dorsal ulnar sensation	May be affected	May be preserved depending on level
Clawing	Present	Present
Localization	Proximal to FCU branch	Distal to FCU branch

Isolated Ulnar vs Combined Median–Ulnar Palsy

Feature	Isolated ulnar	Combined median + ulnar
1st & 2nd lumbricals	Preserved	Weak
3rd & 4th lumbricals	Weak	Weak
Ring/little clawing	Prominent	Present
Index/middle clawing	Less prominent	Can occur
Thenar function	Relatively preserved	Impaired
Pinch	Abnormal	More severely impaired
Palm	Ulnar flattening	More generalized flattening

Practical Examination Sequence

HISTORY
Trauma – duration – fracture – Hansen disease -compression – neurological cause

INSPECTION
Clawing – scars – trophic changes – hypothenar/interosseous wasting – palmar flattening

PROXIMAL EXAMINATION
Brachial plexus – carrying angle – cubital tunnel – FCU

MOTOR — EXTRINSIC
FCU – FDP ring/little

MOTOR — INTRINSIC
Finger abduction/adduction – card test – finger crossing

THUMB
Froment – adductor pollicis – FPB – APB – median nerve status

CLAW ASSESSMENT
MCP hyperextension – IP flexion – Bouvier – deformity/assisted/contracture angles

SENSORY
Little finger – ulnar half ring finger – dorsal ulnar hand – two-point discrimination

Tinel / COMPRESSION

FUNCTIONAL TESTS
Key pinch – pulp pinch – coin – ball – palmar cupping

DIFFERENTIAL
High vs low ulnar – combined median-ulnar – plexus – TOS – systemic neuropathy

Key Take-Home Points

Ulnar palsy examination should start proximally and proceed distally.
FCU is a key muscle for distinguishing high from low ulnar palsy.
Ring and little finger FDP function gives additional localization.
Froment sign demonstrates adductor pollicis weakness by FPL compensation.
Remember DAB and PAD for interosseous function.
Wartenberg sign is persistent abduction of the little finger.
Classical clawing results from loss of intrinsic MCP flexion and IP extension.
Isolated ulnar palsy mainly claws the ulnar digits; combined median-ulnar palsy may produce a more complete claw.
Bouvier test is crucial because it determines whether correcting MCP hyperextension restores IP extension.
Always assess whether the deformity is supple or fixed before planning reconstruction.
Dorsal ulnar sensation and extrinsic muscle function help localize the level of injury.
Functional examination—pinch, grip, ball holding and palmar cupping—is as important as simply demonstrating the deformity.