Outcomes of flexor tendon repairs in zone 2 subzones with early active mobilization.

We report on the outcomes of flexor tendon repair in zone 2 subzones with early active mobilization in 102 fingers in 88 consecutive patients. There were 28, 53, 15, and six fingers with repairs in zones 2A to 2D, respectively. Rupture of the repair occurred in four fingers, all in zone 2B. Excluding those with repair ruptures, the mean total active motion was 230° (range 143°-286°). Evaluated with Tang's criteria, the outcomes were ranked excellent in 39 fingers, good in 46, fair in ten, poor in three, and failure in four. The outcomes in zone 2C were significantly inferior to those in zones 2B and 2D ( p = 0.02). Our results suggest that the tendon laceration in the area covered by the A2 pulley (zone 2C) is the most difficult area to obtain satisfactory active digital motion and tendon repair in zone 2B is the area where the risk of rupture is highest. LEVEL OF EVIDENCE: IV.

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

UNLABELLED: 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.

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.

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.

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.

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).

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.

Experimental study of two new flexor tendon suture techniques for postoperative early active flexion exercises.

We used a rabbit model to test the postoperative mechanical strengths of two new tendon suture techniques. These were compared with the conventional modified Kessler and double looped suture techniques. For each technique, maximum load until 3 mm gap, load at 1 mm gap and ultimate load were measured at the time of operation and at weeks 1 and 3 after operation. Maximum load until 3 mm gap and load at 1 mm gap were significantly higher in the new techniques than in the conventional techniques at the time of operation and at 1 week; there was no statistical difference between the four techniques at 3 weeks. No technique resulted in a decrease in maximum load until 3 mm gap, load at 1 mm gap and ultimate load at 1 week. The new techniques reported here have the potential to withstand early active flexion exercises.

Reconstruction of a congenital hypoplastic thumb with use of a free vascularized metatarsophalangeal joint.

Reconstruction of a Blauth type-IIIB hypoplastic thumb with use of a free vascularized metatarsophalangeal joint was performed in four patients (four hands). Several tendon transfers also were performed, either primarily or secondarily, to mobilize the reconstructed thumb. Three patients (three hands) were followed for at least two years after the reconstruction; the results for these three patients were compared with those for four patients (six hands) who had been managed with pollicization of the index finger because of a similar deformity of the thumb. The patients were evaluated with regard to grip strength, key-pinch strength, and the range of motion of the joints of the thumb in the operatively treated and contralateral hands as well as with regard to skill in performing activities of daily living as assessed with use of the Kobe hand-function test. Although the appearance of the thumb was closer to normal in the group that had had the pollicization procedure, total function of the hand and grip strength were greater in the group that had had the transfer procedure. We believe that reconstruction of an unstable hypoplastic (Blauth type-IIIB) thumb with use of a vascularized metatarsophalangeal joint is an acceptable alternative to pollicization of the index finger.

The selectivity of regenerating motor and sensory axons.

Functional results of peripheral nerve repair have been hampered by misdirection of regenerating axons. The purpose of this study was to determine in a rat femoral nerve model whether regenerating motor and sensory axons from a proximal nerve stump select the appropriate distal motor or sensory branch. In two experiments, the proximal stump of the motor or sensory branches was sutured to the distal motor sensory stumps, so that the three branches were parallel and the three transected ends faced in the same direction. More regenerated axons from both the proximal motor and sensory stumps entered the distal sensory stump. The number of misdirected axons did not decrease over time. The selective regeneration of motor axons toward the distal motor stump could not be validated. In this study, neurotropism appeared to play a measurable role in sensory axon regeneration, but not in motor axon regeneration. Pruning of the misdirected axons was not demonstrated.

The selectivity of motor axons during regeneration with sensory axons.

This study investigated the influence of selective sensory regeneration on less selective motor regeneration in a rat femoral nerve model. The proximal stump of the motor branch to the quadriceps muscle was sutured to the distal stumps of one motor and one sensory branch. Regenerated sensory axons were degenerated secondarily, and motor regeneration was later evaluated. The distal sensory stump attracted both regenerating sensory and motor axons. Misdirected motor axons in the distal branches were not pruned over time. The authors hypothesized that motor regeneration may be been influenced by selective sensory regeneration or non-selective neurotropic attraction.

Microsurgical toenail transfer to the hand.

Free nonvascularized toenail grafts have been used to reconstruct congenital or traumatic nail defects of the thumb or finger. Unfortunately, these transfers often result in deformity or atrophy. To avoid these undesirable results, microsurgical free vascularized toenail transfer was performed in 10 patients, 3 for congenital nail absence and 7 for traumatic nail defects. Patient age averaged 17 years (range 2 to 32 years). In contrast with previous reports, the whole big or second toenail complex without pulp was used in reconstruction. All 10 nails were successfully transferred with complete survival. No digits required reexploration. There were no donor- or recipient-site problems. Follow-up averaged 3 years, with a range of 14 months to 5 years and 4 months. Appropriate nail growth occurred in the congenital patients. No atrophy of the nail complex was found as long as sufficient bony support was present (9 of 10 cases). Whole free vascularized toenail transfers for reconstruction of congenital and traumatic nailbed defects achieve excellent aesthetic results while maintaining normal hand function.

Replantation of untidily amputated finger, hand, and arm: experience of 99 replantations in 66 cases.

Three problems the authors think important in replantation of untidy amputations are discussed based on our 99 replantations with the success rate of 92.6% over a 4-year period. To restore circulation in this type of amputation, such techniques as transfer of blood vessels, use of a neurovascular island flap with neurovascular anastomoses at its distal margin, vein graft, and free split-skin graft directly on the anastomosed blood vessels are recommended. Recovery of tendon gliding when replanted proximally to the MP joint was reasonably good but not when replanted distally to it. Recovery of intrinsic muscles was generally poor. Protective sensation was usually regained, although occasionally accompanied by paresthesia. Amputation of single digit was found not to be an absolute indication for replantation except for the thumb. In multiple digital amputation, more important digits should be restored by amputated digits in better condition. Replantation for cosmetic improvement may be justified in such cases as unmarried young females. In infants, replantation is especially worthwhile because good functional recovery and good further growth can be expected.