Yutaka Maki

Clinical outcomes of early active mobilization following flexor tendon repair using the six-strand technique: short- and long-term evaluations.

We evaluated the factors influencing outcomes of flexor tendon repair in 112 fingers using a six-strand suture with the Yoshizu #1 technique and early postoperative active mobilization in 101 consecutive patients. A total of 32 fingers had injuries in Zone I, 78 in Zone II, and two in Zone III. The mean follow-up period was 6 months; 16 patients (19 fingers) participated in long-term follow-up of 2 to 16 years. The total active motion was 230° SD 29°; it correlated negatively with age. The total active motion was 231° SD 28° after repair of the lacerated flexor digitorum superficialis tendon, and was 205° SD 37° after excision of the flexor digitorum superficialis tendon ends (p = 0.0093). A total of 19 fingers showed no significant increases in total active motion more than 2 years after surgery. The rupture rate was 5.4% in our patients and related to surgeons’ level of expertise. Five out of six ruptured tendons were repaired by inexperienced surgeons. Level of Evidence IV

Outcomes of release of the entire A4 pulley after flexor tendon repairs in zone 2A followed by early active mobilization

We report the outcomes of repair of the flexor digitorum profundus tendon in zone 2a in 22 fingers. The tendon was repaired with a six-strand repair method and the A4 pulley was completely released. Release of the C2 pulley combined with the A4 pulley was necessary in 12 fingers, nine fingers underwent a complete release of the A3, C2, and A4 pulleys, and one finger underwent a release of the C1, A3, C2, and A4 pulleys. The mean total active motion of the three finger joints was 234° at 5 to 12 months of follow-up. No bowstringing was noted in these fingers. The good and excellent recovery of active digital motion was in 20 (91%) out of 22 fingers according to Strickland’s criteria or Tang’s criteria. Our results suggest that release of the A3, C2, and A4 pulleys makes the repair surgery easier and does not cause tendon bowstringing. Level of Evidence: IV

Functional and cosmetic results of fingertip replantation: anastomosing only the digital artery.

In fingertip amputations, conventional stump plasty provides an almost acceptable functional result. However, replanting fingertips can preserve the nail and minimize loss of function. We investigated the functional and cosmetic results of fingertip replantation at the terminal branch of the digital artery. Outcomes were nailbed width and distal-segment length; sensory recovery; and range of motion (ROM) of thumb-interphalangeal (IP) or finger–distal interphalangeal (DIP) joints, and total active motion (TAM) of the replanted finger. Of 15 fingertips replanted after only arterial anastomosis, 13 were successful, and 12 were studied. After a median of 1.3 years, mean nailbed widths and distal-segment lengths were 95.4% and 93.0%, respectively, of the contralateral finger. Average TAM and ROM of the thumb-IP or finger-DIP joints were 92.0% and 83.0% of normal, respectively. Semmes-Weinstein results were blue (3.22 to 3.61) in 4 fingers and purple (3.84 to 4.31) in 8; the mean result from the 2-point discrimination test was 5.9 mm (range, 3 to 11 mm). Thus, amputated fingertips should be aggressively replanted.

Clinical results of releasing the entire A2 pulley after flexor tendon repair in zone 2C

We report the results of complete release of the entire A2 pulley after zone 2C flexor tendon repair followed by early postoperative active mobilization in seven fingers and their comparisons with 33 fingers with partial A2 pulley release. In seven fingers, release of the entire A2 pulley was necessary to allow free gliding of the repairs in five fingers and complete release of both the A2 and C1 pulleys was necessary in two. No bowstringing was clinically evident in any finger. Two fingers required tenolysis. Using Tang’s criteria, the function of two digits was ranked as excellent, four good and one fair; there was no failure. The functional return in these seven fingers was similar with that in 33 fingers with partial A2 pulley release; in these patients only one finger required tenolysis. Our results support the suggestion that release of the entire A2 pulley together with the adjacent C1 pulley does not clinically affect finger motion or cause tendon bowstringing, provided that the other pulleys are left intact. Level of evidence: IV

Both stump area and volume of distal sensory nerve segments influence the regeneration of sensory axons in rats

We examined the influence of both stump area and volume of a distal sensory nerve segment on neurotropic induction of regenerating sensory axons in a rat saphenous nerve model. In group 1 (n = 10) the proximal stump of the severed saphenous nerve was inserted into the proximal channel, and a 2 cm free nerve segment and a double-barrelled 1 cm free nerve segment were inserted into the distal two channels of a silicone Y-chamber. In group 2 (n = 10), 2 cm and 1 cm free nerve segments were inserted into the distal two channels of a Y-chamber. The gap between the stumps was set at 4 mm. After six weeks, we counted and compared the number of regenerated myelinated sensory axons in the distal two channels. Significantly more axons regenerated in the wider stump area channel of group 1 and in the larger volume channel of group 2 than in the opposite channel in either group (p < 0.05 in each case).

Comparison of the neurotropic effects of motor and sensory Schwann cells during regeneration of peripheral nerves.

We examined the inductive ability of motor and sensory Schwann cells on regeneration of motor and sensory axons using a silastic Y chamber, and Lewis rats L5 ventral root (motor) and saphenous nerve (sensory). We developed four experimental models: motor-motor nerve group-proximal motor stump with distal fresh and frozen/thawed motor nerve segments (n = 7); sensory-sensory nerve group-proximal sensory stump with distal fresh and frozen/thawed sensory nerve segments (n = 7); motor-sensory nerve group-proximal motor stump with distal fresh and frozen/thawed sensory segments (n = 8); and sensory-motor nerve group-proximal sensory stump with distal fresh and frozen/thawed motor segments (n = 8). The gap was set at 4 mm. Six weeks postoperatively we compared the number of regenerated myelinated axons in the two distal channels, and found that sensory Schwann cells have a strong inductive ability for regeneration of both sensory and motor axons. Motor Schwann cells have weak inductive ability for regeneration of motor axons and no inductive ability for regeneration of sensory axons.

Selective regeneration of motor and sensory axons in an experimental peripheral nerve model without endorgans.

We assessed the selectivity of motor and sensory axon regeneration towards the distal motor and sensory nerve segments that were disconnected from endorgans in a rat silicone Y chamber model. The L5 ventral root was used as a pure motor nerve, and the saphenous nerve was used as a sensory nerve. In experiment 1 (n=11), the proximal stump of the L5 ventral root, a 1-cm-long L5 ventral root segment and a saphenous nerve segment were inserted into a silicone Y chamber. In experiment 2 (n=11), the proximal stump of the saphenous nerve, a L5 ventral root segment and a saphenous nerve segment were inserted into a Y chamber. The distance between the nerve stumps was 5 mm. Six weeks later, the number of regenerated myelinated motor and sensory axons was measured and compared in the distal two channels. Motor axons showed no selective regeneration, but sensory axons did.

Lack of topographical specificity in peripheral nerve regeneration in rats.

In a previous study we found that sensory regeneration was neurotropically selective regardless of the end organ, but motor regeneration was not, which made us doubt the existence of topographic specificity. The purpose of the present study was to confirm the existence of topographic specificity in rats. The proximal stump of either the peroneal or tibial nerve was inserted into the proximal limb of a silicone Y-chamber. Both distal stumps of peroneal and tibial nerve were inserted into the distal limbs. The gap between the stumps was set at either 4 mm (n = 8, on each subgroup) or 8 mm (n = 8, on each subgroup). Six weeks later the number of regenerated axons in the distal two limbs were counted and compared. The number of regenerated axons towards the distal tibial nerve side was significantly larger in every model. Regenerated axons from the proximal peroneal stump did not preferentially choose the distal peroneal stump. The existence of topographic specificity is unlikely.

Flexor tendon repair in a rabbit model using a core of extensor retinaculum with synovial membrane : An experimental study

In this histological and biomechanical study in two groups of rabbits, a piece of the extensor retinaculum with its synovial membrane was inserted as a biological “core” into a hole at the centre of both stumps of a severed tendon, which was repaired with interrupted sutures. In the other group, the tendon was sutured without a “core”. In the “core” group, proliferation and migration of fibroblasts from both tendon surfaces and the “core” surface toward the deep layer of the suture site was seen 2 weeks after operation. New collagen fibres, aligned parallel to the long axis of the tendon, could also be seen 4 weeks after operation, and healing was more advanced than in the coreless model. The maximum force to produce a gap in the “core” tendon was 82% greater than in the coreless tendon 4 weeks after operation.

Ultrasound-guided supraclavicular brachial plexus block in a patient with a cervical rib

To the Editor, Anatomical variants can make regional anesthesia challenging even when ultrasound guidance is employed. This report describes our experience while performing ultrasound-guided supraclavicular brachial plexus block in a patient with a cervical rib. Patient consent was obtained for publication of this report. A 57-yr-old male (height, 160 cm; weight, 44 kg) was admitted with an open fracture of his right middle phalanx and a lacerated digital artery of his right index finger. His medical history included type 2 diabetes mellitus treated with oral hypoglycemic drugs. The preoperative chest radiograph showed a left cervical rib (Figure A) and a normal right clavicle. He reported no symptoms of thoracic outlet syndrome in either of his upper limbs. An open reduction and internal fixation of the middle phalanx and anastomosis of the digital artery were performed. The nerves surrounding the subclavian artery were identified by placing a high-frequency (6-15 MHz) ultrasound probe (EDGE ; SonoSite, Tokyo, Japan) above the clavicle. A bony structure was identified lateral to the nerves, indicated by a smooth hyperechoic edge with a posterior acoustic shadow (Figure C). In light of this finding, we reassessed the chest radiographs and magnified the right cervical area where a right cervical rib was confirmed (Figure B). While the cervical rib partially obstructed the needle path for a lateral in-plane, supraclavicular approach to the brachial plexus, we were able to inject 10 mL of both 1% mepivacaine and 0.5% bupivacaine (total 20 mL) with ultrasound guidance. The distribution and duration of the sensory block were sufficient for a surgical repair lasting 109 min. Postoperative neuropathy was not observed. Cervical ribs are supernumerary ribs which arise from the seventh cervical vertebra and are present in 0.05-3.0% of the population. In the study by Viertel et al., the authors found that almost 60% of patients with cervical ribs had a unilateral rib, while the remaining patients had bilateral cervical ribs. Although the majority of cervical ribs are not clinically relevant, these anomalies may cause thoracic outlet syndrome. Complete cervical ribs attach to the lateral first rib through a true joint, whereas incomplete cervical ribs typically have a ligamentous extension to the first rib. The structure is usually diagnosed by plain radiography or computed tomography. Structures other than cervical ribs may also be observed in the supraclavicular area. Calcified cervical lymph nodes may appear similar to bones on ultrasound imaging. Lymph nodes may become calcified due to sarcoidosis, lymph node metastasis from malignant cancers (e.g., thyroid, lung, or breast cancer), and infectious diseases (e.g., tuberculosis). When a bone-like structure is observed surrounding the brachial plexus on the supraclavicular ultrasound image, detailed radiographic imaging is indicated to rule out these less benign conditions. While a supraclavicular approach to the brachial plexus was used in this case, the cervical rib was also identified on the ultrasound image using an interscalene approach (Figure D). We prefer to use the lateral in-plane supraclavicular approach to avoid vascular injury and to visualize the entire needle path. If a larger cervical rib had T. Watanabe, MD (&) H. Baba, MD, PhD Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan e-mail: tatsu-w@med.niigata-u.ac.jp