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Ulnar Nerve Transposition versus Epicondylectomy
Ulnar nerve compression at the elbow is the second most commonly encountered entrapment neuropathy of the upper extremity, exceeded in frequency only by median nerve entrapment at the carpal tunnel. Various techniques have been described for achieving cubital tunnel decompression. Acceptable success rates have been achieved by most of these procedures.
One consistent parameter used to predict surgical outcome is the extent of ulnar neuropathy at the time of treatment. In 1950, McGowan proposed a grading system for the extent of neurological involvement as it relates to ulnar neuropathy (Table 51–1). This system is widely used in an attempt to describe the extent of ulnar neuropathy and assess treatment outcomes.
When ulnar neuropathy is refractory to nonoperative treatment, two surgical procedures that have been widely practiced are ulnar nerve transposition and medial epicondylectomy. Each technique attempts to alleviate compression of the nerve. Medial epicondylectomy mitigates the tethering effect of the prominent epicondyle on the ulnar nerve while increasing the space available for the nerve within the cubital tunnel. Transposition removes the nerve from its confinement along the medial elbow and attempts to create a more forgiving bed anterior to the epicondyle within soft tissue. Our experience has primarily involved the use of anterior transposition and has resulted in symptomatic improvement in 80 to 90% of patients. Other authors have demonstrated equally good results using medial epicondylectomy as their primary procedure. Regardless of which procedure is performed, alleviation of paresthesias, hypoesthesias, and milder symptoms is less variable and more predictable than recovery of motor function and return of sensibility.
Indications
Transposition
1. Repositioning the nerve during operative reduction of acute fractures and dislocations
2. Repositioning the nerve following total elbow arthroplasty
3. Repositioning the nerve following ulnar collateral ligament reconstruction
4. Repositioning the nerve in an overhead thrower with ulnar neuropathy
5. Severe ulnar nerve neuropathy (McGowan grade III)
6. Prior unsuccessful ulnar nerve decompression surgery
Epicondylectomy
Mild ulnar nerve neuropathy (McGowan grades I and II).
Contraindications
Transposition
1. Ulnar neuropathy that has not been given an adequate trial (3 months) of nonoperative treatment
2. Metabolic ulnar neuropathy (diabetes mellitus, alcoholism, hypothyroidism, renal disease, Hansen’s disease, uremia, multiple myeloma, amyloidosis, vitamin deficiency)
Grade I | Grade II | Grade III |
|---|---|---|
Intermittent paresthesia Minor hypothesia No motor weakness No muscular atrophy Mild symptoms | Paresthesia Mild weakness of ulnar-innervated muscles Early signs of muscular atrophy Persistent symptoms | Obvious loss of sensation Significant functional and motor impairment Muscle atrophy of hand intrinsics Possible digital clawing of ring and little fingers |
Epicondylectomy
1. Concomitant reconstruction of the ulnar collateral ligament (UCL)
2. High-level overhead-throwing athlete
Etiology
There are five potential sites of ulnar nerve compression at the elbow:
1. Intermuscular septum
a. Arcade of Struthers
b. Hypertrophy of the medial head of the triceps
c. Epitrochleo-anconeus muscle
2. Area of medial epicondyle
a. Valgus deformity of distal humerus (fracture malunion, congenital cubitus valgus)
3. Epicondylar groove
a. Subluxation or dislocation of the nerve
b. Osteophytes
c. Ganglion cyst
d. Rheumatoid synovitis
4. Cubital tunnel
a. Thickened Osborne’s ligament
5. Flexor carpi ulnaris (FCU) aponeurosis
a. Entrance of the nerve into the flexor carpi ulnaris
Physical Examination
1. Rule out “double crush” phenomenon (cervical disk disease or arthritis, thoracic outlet syndrome).
2. Paresthesias in ring and little finger.
3. Percussion test (Tinel’s sign) at cubital tunnel.
4. Elbow flexion test—maintain the elbow in full flexion with the wrist in full extension for 1 minute (analogous to Phalen’s test for carpal tunnel syndrome).
5. Intrinsic hand weakness (late finding)—associated with chronic compression.
Diagnostic Tests
1. Electrodiagnostic studies
a. Beware of false-negative results.
b. Nerve conduction studies do not always correlate with clinical outcome.
c. Important when clinical symptoms/findings are equivocal, when compression may be at multiple sites, or when polyneuropathy or motor neuron disease is suspected.
2. Imaging studies
a. Standard anteroposterior, oblique, and lateral views of the elbow.
b. Epicondylar groove view is useful in patients with arthritic and traumatic conditions of the elbow.
Special Considerations
For chronic neuropathy associated with muscle weakness, nonoperative treatment is generally not effective, and surgery is warranted. Multiple studies have demonstrated that results of ulnar nerve decompression depend on the severity of the nerve involvement. Patients with mild and moderate neuropathy can expect more predictable results than those with more severe, long-standing neuropathy. Following revision surgery, pain and parasthesias can predictably improve; however, the return of motor and sensory loss is variable. The consensus in the literature is that following revision surgery, strength may improve but never returns to normal.
Preoperative Planning and Timing of Surgery
1. Trial of nonoperative treatment for at least 3 to 4 months. Most series in the literature regarding operative treatment average 12 months of symptoms prior to surgical intervention.
2. If local tenderness, numbness, or paresthesias continue despite an adequate trial of conservative care, surgery is usually necessary.
3. If work or leisure activities are compromised, surgery is necessary.
4. In the absence of muscle weakness, however, there is no urgency.
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