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From March 2008 to December 2013, 163 patients with clinically and electrodiagnostically
confirmed cubital tunnel syndrome underwent operative treatment for cubital tunnel
syndrome. Electrodiagnostic studies were conducted and interpreted by a professional
rehabilitation doctor at our institution. We recommended operative treatment if patients
presented with intrinsic atrophy or significant hand weakness and had clinical symptoms
of tingling, pain, or weakness after at least 2 months of conservative treatment,
such as night splinting and tendon gliding exercises.

The inclusion criteria comprised surgically treated cubital tunnel syndrome and follow-up
data that were available for a minimum of 1 year after surgery. The exclusion criteria
were as follows: electrodiagnostically silent cubital tunnel syndrome, cubitus valgus,
osseous canal deformity from previous trauma or osteophytes of the elbow joint, previous
surgery for cubital tunnel syndrome, associated cervical radiculopathy, carpal tunnel
syndrome, ulnar tunnel syndrome, thoracic outlet syndrome, diabetes mellitus, hypothyroidism,
worker’s compensation issues, and follow-up data unavailability for a minimum of 1 year
after surgery.

Based on these criteria, four patients with electrodiagnostically silent cubital tunnel
syndrome, nine patients with cubitus valgus, 14 patients with elbow osteoarthritis,
seven patients requiring revision surgery, 13 patients with one of the associated
diseases mentioned above, and five worker’s compensation patients were excluded. Four
patients were lost to follow-up. Consequently, 56 patients were excluded, and 107
patients were available for the study (Fig. 1). Among our study population, 12 patients had bilateral cubital tunnel syndrome.
In these patients, we analyzed only the dominant extremity. We then had 51 patients
who underwent an ulnar nerve stability-based approach involving either simple decompression
(?=?37) or anterior transposition (?=?14) via a small incision (group A) and 56 patients who underwent anterior subcutaneous
transposition of the ulnar nerve via a classic incision (group B). There was a distinct
time period for each type of operation. Briefly, we performed anterior transposition
of the ulnar nerve via a classic incision earlier in the duration of the study and
changed the technique to an ulnar nerve stability-based approach via a small incision
in June 2010. Group A included 32 men and 19 women with a mean age of 38.3?±?15.0 years
(range, 20–68 years) at the time of surgery. The duration of symptoms to surgery was
24.1?±?31.2 months (range, 3–120 months). The mean follow-up period after the operation
was 30.2?±?10.8 months (range, 12–48 months). Group B included 37 men and 19 women
with a mean age of 35.7?±?16.7 years (range, 19–66 years) at the time of surgery.
The duration of symptoms to surgery was 23.0?±?26.8 months (range, 5–96 months). The
mean follow-up period after the operation was 34.1?±?13.2 months (range, 12–60 months;
Table 1). Our institutional review board approved the study and waived the requirement for
informed consent.

Fig. 1. The CONSORT diagram of enrollment and analysis in this study

Table 1. Baseline demographic and clinical characteristics

Dellon staging was applied in order to grade the preoperative severity of ulnar neuropathy
20]. According to this staging system, patients with intermittent paresthesia and subjective
weakness are classified as having mild ulnar nerve compression (grade I). Patients
who have moderate compression show intermittent paresthesia and measurable weakness
in pinch and grip strength (grade II). Patients with persistent paresthesia, abnormal
two-point discrimination, and measurable weakness in pinch and grip strength with
intrinsic atrophy are classified as having severe compression (grade III). Accordingly,
nine patients were rated as grade I, 27 as grade II, and the remaining 15 as grade
III in group A; similarly, 11 patients were rated as grade I, 26 as grade II, and
the remaining 19 as grade III in group B (Table 1).

An independent observer (BRK) blinded to the method of operation performed the preoperative
and postoperative assessments. Each patient was assessed for grip and pinch strength
and two-point discrimination (2PD) and completed the disabilities of arm, shoulder,
and hand (DASH) survey preoperatively and at each follow-up 21]. Pinch and grip strength were measured using baseline hydraulic pinch and grip dynamometers.
The clinical outcome at the final follow-up was based on the Bishop rating system,
which assesses subjective and objective parameters 9]. Subjective parameters included severity of residual symptoms (asymptomatic, 3; mild,
2; moderate, 1; severe, 0), subjective improvement compared with the preoperative
period (better, 2; unchanged, 1; worse, 0), and preoperative and postoperative work
status (working previous job, 2; changed job, 1; not working, 0). Objective parameters
were grip strength compared with the normal side (80 % or more, 1; less than 80 %,
0) and sensory measurement of static two-point discrimination (6 mm or less, 1; more
than 6 mm, 0). The score was defined as excellent (8 to 9), good (5 to 7), fair (3
to 4), and poor (0 to 2).

Surgical technique

Under general anesthesia, the patient was placed in a supine position with the affected
arm supported by a hand table and sterilely prepped and draped. After exsanguination
of the limb with a sterile tourniquet, the shoulder was placed at 90° of abduction
and slight external rotation and the medial epicondyle and olecranon were marked.

In group A, a 2.5-cm longitudinal skin incision was made between the medial epicondyle
and the olecranon. Then, the subcutaneous tissues were gently and carefully separated
with dissecting scissors. With the help of mini retractors, the ulnar nerve was located
by releasing the brachial fascia just proximal to the cubital tunnel. Blunt dissection
was carried out proximally using a curved mosquito hemostat to create a cavity between
the subcutaneous tissue and the brachial fascia. A Cobb elevator was then gently introduced
into this cavity to extend it at least 8 cm proximal to the medial epicondyle. A long
nasal speculum was introduced into the cavity, and the brachial fascia and arcade
of Struthers were released under direct visualization (Fig. 2). To allow the operating light to reach the deep operating field, the shoulder of
the patient was adducted about 20°, and the beam of the light was almost parallel
to the upper arm. After removing the nasal speculum, Osborne’s ligament was released.
Then, a distal cavity was created between the subcutaneous tissue and Osborne’s fascia,
followed by the release of Osborne’s fascia and the deep flexor-pronator aponeurosis.
A short nasal speculum was introduced at that moment to assist with clear visualization
of the structures (Fig. 3). Only the superficial surface of the nerve was exposed, and neurolysis was not performed
to decrease the possibility of nerve subluxation. After complete release of all potential
sources of structural nerve compression, the stability of the ulnar nerve was tested
by moving the elbow through the full range of motion. If the nerve remained within
the cubital tunnel throughout elbow flexion, it was considered stable. If the nerve
displaced onto the medial epicondyle during flexion or if it did not sit well within
the cubital tunnel, it was considered unstable. In such cases where instability was
identified intraoperatively, the skin incision was extended 1 cm proximally and distally
to transpose the nerve anteriorly. The soft tissue above the flexor-pronator muscle
group was elevated, and the ulnar nerve was then carefully lifted from its bed with
its accompanying longitudinal vascular supply intact. Segmental feeding vessels were
identified and ligated to prevent tethering. Neurolysis of the posterior motor branches
from the main ulnar nerve was performed to allow adequate anterior transposition if
there was tension. The medial intermuscular septum was also excised as part of the
anterior transposition. A fascial sling raised from the underlying muscle fascia was
created to prevent slippage of the nerve after transposition (Fig. 4).

Fig. 2. While introducing and opening a long nasal speculum over the brachial fascia, the
proximal nerve compression structures including the arcade of Struthers were completely
released

Fig. 3. After releasing the proximal nerve compression structures, Osborne’s ligament, Osborne’s
fascia, and the deep flexor-pronator aponeurosis were sequentially released

Fig. 4. In patients with an unstable ulnar nerve, the nerve was anteriorly transposed, and
a fascial sling (*) was created

In group B, a 10-cm incision was placed behind the medial epicondyle. All points of
ulnar nerve compression were completely released as described earlier, and care was
taken to protect branches of the medial antebrachial cutaneous nerve. The soft tissue
above the flexor-pronator muscle origin was elevated, and the ulnar nerve was then
lifted from its bed as described earlier. The medial intermuscular septum was also
excised, and a fascial sling raised from the underlying muscle fascia was created.

After skin closure, a soft dressing and an elastic bandage were applied. Early movement
of the fingers, wrist, forearm, elbow, and shoulder was encouraged.

Statistical analysis

SPSS Statistics version 18.0 (SPSS, Inc, IBM®, Chicago, IL, USA) was used for statistical
analyses. Group results were compared using Pearson’s chi-squared test or Fisher’s
exact test for categorical variables and Student’s t test for continuous variables. The level of significance was set at p??0.05.