ENTRAPMENTSITE2—ULNARSULCUS—TARDY
ULNARPALSY
- Anatomy:At the elbow the nerve leaves this fascia
and passes posterior to the medial epicondyle of the
humerus (ulnar sulcus—entrapment site 2). Compre-
ssion at the elbow is the second most common nerve
entrapment of the upper extremity. Common risk fac-
torsare leaning on elbows, tight casts after fracture,
compressive trauma, wrestling without elbow pads,
excessive flexion (as in prolonged driving), and exten-
sion have been implicated as causes of this problem.
Anatomic predisposition to tardy ulnar palsy (Kimura,
2001) is also a risk factor. - Symptoms and signs: Pain, paresthesia, and/or
numbness in the volar aspect of the fifth and median
fourth digits, and over the hypothenar eminence of the
affected hand, increasing with elbow flexion. Motor
weakness and/or atrophy often presents in the hand
intrinsic muscles innervated by the ulnar nerve.
Flexion contracture of the PIP, digit V or a claw hand
may be present (partial flexion of the proximal and
distal interphalangeal joints, with extension of the
metacarpophalangeal joints). Grip strength may be
diminished. - Treatment: Conservative course of pain control,
occupational therapy for muscle strengthening and
maintaining the range of motion. Relative rest should
include avoiding exacerbating activities. Padding
and/or splinting around the elbow may be used. If
neurologic symptoms are progressive, surgery may
be required. Two primary surgical procedures used
are simple ulnar nerve release (UNR) and ulnar
nerve transposition(UNT). It should be recognized
that the UNT is a relatively more involved procedure
with a higher complication rate, including reentrap-
ment.
ENTRAPMENTSITE3—CUBITALTUNNELSYNDROME
- Anatomy:The ulnar nerve enters the cubital tunnel
at the humeroulnar aponeurotic arcade(HUA). It lies
on the ulnar collateral ligament between the two
heads of the flexor carpi ulnaris. The nerve passes
beneath the HUA, pierces the flexor carpi ulnaris
FCU, and then exits at the distal end of the cubital
tunnel through the deep flexor pronator aponeurosis
(DFPA). The length of the cubital tunnel may be from
4–5 cm. Entrapment may occur at the entrance, mid-
point, or exit of the tunnel. - Risk factors:Lesions here are most often nontrau-
matic, repetitive motion injuries, and may have an
anatomical predisposition. - Symptoms and signs:Clinical presentation of the
cubital tunnel syndrome will be similar to compres-
sion at the retrocondylar(RTC) groove, making these
diagnoses a challenge to distinguish from each other.
A positive Tinel’s sign over the cubital tunnel instead
of over the RTC groove may be one of only a few dif-
ferentiating clinical findings. Symptoms include
Wartenberg’s sign of weakness with fifth finger
abduction, and Froment’s sign (flexion of the thumb
to activate the FPL). This may be observed by asking
the patient to pinch a piece of paper between first and
second metacarpals. In response to a strong pull on
the paper, the patient contracts the FPL to substitute
for the weak first dorsal interosseus and adductor pol-
licis muscles.- Treatment:For cubital tunnel syndrome is initially
conservative, as in the case of tardy ulnar palsy, men-
tioned above. Should symptoms progress with motor
decline, surgery should be considered. The procedure
of choice for nontraumatic cubital tunnel syndrome is
a cubital tunnel release.
ENTRAPMENTSITES 4 AND 5- Anatomy:These sites are at the wrist at Guyon’s
canal and/or in the palm. Borders are medially the
pisiform bone, laterally the hook of the hamate, the
roof is the tendon of the FCU and the floor the carpal
ligament. In the canal the ulnar nerve divides into two
branches. The deep branch accompanied by the ulnar
artery winds around the hook of the hamate, supplies
the interossei, the 3rd and 4th lumbricals, the adduc-
tor pollicis, the 1st dorsal interosseous and the deep
head of the flexor pollicis brevis. The superficial
branch supplies the palmaris brevis and terminates as
sensory nerve to digits 4 and 5. - Risk factors:Bicycle riding, push-ups, flute or violin
playing, occupational trauma, scars, ganglion cysts,
ulnar artery aneurysms, and lipomas. Compression
after exit from Guyon’s canal (palmar branch) results
in weakness of ulnar innervated intrinsics, but no sen-
sory deficit. Occasionally the abductor digiti minimi
is spared. This syndrome is seen in bicyclists due to
the pressure on the horn handlebarseven after one
ride, which formerly (using different handlebars) was
only observed after prolonged multiple rides.
Compression of superficial and deep branches within
the canal affects motor and sensory branches.
Compression of superficial branch in the canal causes
sensory loss of the ulnar half of the 4th digit and the
5th digit. - Symptoms and signs:Wrist pain, weakness especially
in grasp, numbness, tingling in ulnar nerve distribution,
worse at night. Physical examination may confirm the
weakness in grasp and finger abduction. If sensory
involvement is present, loss is in ulnar nerve distribu-
tion. Provocative maneuvers that may be positive are
Tinel’s, Phalen’s, or reverse Phalen’s (Wormer’s test).
328 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE