We investigated the effect of progesterone on the nerve during lengthening of the limb in rats. The sciatic nerves of rats were elongated by leg lengthening for ten days at 3 mm per day. On alternate days between the day after the operation and nerve dissection, the progesterone-treated group received subcutaneous injections of 1 mg progesterone in sesame oil and the control group received oil only. On the fifth, tenth and 17th day, the sciatic nerves were excised at the midpoint of the femur and the mRNA expression level of myelin protein P0 was analysed by quantitative real time polymerase chain reaction. On day 52 nodal length was examined by electron microscopy, followed by an examination of the compound muscle action potential (C-MAP) amplitude and the motor conduction velocity (MCV) of the tibial nerve on days 17 and 52. The P0 (a major myelin glycoprotein) mRNA expression level in the progesterone-treated group increased by 46.6% and 38.7% on days five and ten, respectively. On day 52, the nodal length in the progesterone-treated group was smaller than that in the control group, and the MCV of the progesterone-treated group had been restored to normal.

Progesterone might accelerate the restoration of demyelination caused by nerve elongation by activating myelin synthesis.

We performed a new operation for ulnar neuropathy caused by recurrent dislocation at the medial epicondyle.

There were eleven patients, eight men and three women, with an average age of 52 years (24–74 years) at the time of surgery. The mean duration of symptoms was 23 months. The severity of the symptoms was McGowan grade 1 in five patients, grade 2 in five patients, and grade 3 in one patient. The operation consisted of ulnar groove plasty proximal to the cubital tunnel. The ulnar nerve was replaced into this reconstructed groove. The nerve was confirmed to be stable throughout the full range of elbow motion.

The cubital tunnel retinaculum of all patients was hypoplastic and the dislocated portion of the ulnar nerves was hard. One nerve showed severe adhesion around the dislocation site. One patient had a pseudo-neuroma. All patients were relieved of discomfort, and motor and sensory function were recovered. The ulnar nerve in the groove showed neither irritation nor adhesion. In patients with grade 1, symptoms or numbness of the fingers was relieved within three months of the operation. Sensory disturbances in patients with grade 2 symptoms also improved within six months. Grade 2 patients with intrinsic muscle weakness regained normal muscular power, and these with patients with intrinsic muscle atrophy had showed increasing muscular power. The patient with grade 3 symptomes recovered normal sensation after 1 year; clawing of the ring and little fin-gers recovered, and the muscle volume was increased.

Friction ulnar neuropathy has been treated traditionally by anterior transpositon or medial epicondylectomy. The ulnar nerve may become entrapped in scar tissue after these operations. We believe that this anatomical position is optimum for the nerve and that this procedure is essential for treatment of friction neuropathy.