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Biomedical subjects

B S Lutz

Publications and source records attributed to B S Lutz.

At least 19 recordsLinked to original sources
PubMed2001

Specificity of reinnervation and motor recovery after interposition of an artificial barrier between transected and repaired nerves in adjacency--an experimental study in the rat.

Non-specific re-innervation of target organs caused by misdirected axonal growth at the repair site is regarded as one reason for a poor functional outcome after peripheral nerve transsection and repair. This study investigates the rate of aberrant re-innervation and its influence on motor recovery in the rat sciatic nerve using artificial sheets as barrier between tibial and peroneal nerves. The sciatic nerve was transsected and repaired as follows: epineural sutures (A x 6), fascicular repair of tibial and peroneal nerves respectively (B x 8), and the same as in group B, but separating both nerves using an Integra-sheet with silicone (C x 8), or Integra without silicone (D x 8). As control, solely the tibial nerve was transsected and repaired (E x 5). Final investigations after 4 months revealed that in group C, 50% of the Integra-silicone sheets were dislocated. No dislocation was found in group D. Muscle contraction force of the gastrocnemius muscle was significantly higher in group E as compared to all other groups. However although not significant, group D showed a consistently higher muscle contraction force than groups A, B, and C. Histology in groups A, B, and C with dislocated sheets demonstrated multiple axons growing from the tibial to the peroneal nerve and vice versa. In groups D and E, no such axonal growth was visible. These findings were confirmed by a significantly higher rate of specific reinnervation of the soleus muscle using sequential retrograde double labelling technique. Results of this study suggest that an artificial sheet such as Integra bears the potential of preventing aberrant re-innervation between repaired adjacent nerves resulting in improved motor recovery. Clinically, this technique may be of importance for brachial plexus, sciatic nerve, and facial nerve repair.

Animals↗
PubMed2001

Interposition of a pedicle fat flap significantly improves specificity of reinnervation and motor recovery after repair of transected nerves in adjacency in rats.

Despite highest standards in nerve repair, functional recovery following nerve transection still remains unsatisfactory. Nonspecific reinnervation of target organs caused by misdirected axonal growth at the repair site is regarded as one reason for a poor functional outcome. This study was conducted to establish a method for preventing aberrant reinnervation between transected and repaired nerves in adjacency. Rat sciatic nerve was transected and repaired as follows: epineural sutures of the sciatic nerve (group A, n = 6), fascicular repair of tibial and peroneal nerves respectively (group B, n = 8), and, as in group B, separating both nerves using a pedicle fat flap as barrier (group C, n = 8). As control only, the tibial nerve was transected and repaired (group D, n = 5). Muscle contraction force of the gastrocnemius muscle was significantly higher in group C as compared with groups A and B after 4 months. Muscle weight showed significantly lower values in group A as compared with groups B, C, and D. Histologic examination in group C revealed little growth of axons from the tibial to the peroneal nerve and vice versa. This axon crossing was observed only when gaps between the fat cells were available. These findings were confirmed by a significantly lower rate of misdirected axonal growth as compared with groups A and B using sequential retrograde double labeling technique of the soleus motoneuron pool. We conclude that a pedicle fat flap significantly prevents aberrant reinnervation between repaired adjacent nerves resulting in significantly improved motor recovery in rats. Clinically, this is of importance for brachial plexus, sciatic nerve, and facial nerve repair.

Adipose Tissue↗
PubMed2000

Selection of donor nerves--an important factor in end-to-side neurorrhaphy.

We have examined the effects of end-to-side neurorrhaphy on peripheral nerve regeneration using the median nerve as recipient nerve and either the antagonistic radial nerve or the agonistic ulnar nerve as donor nerves in rat upper limbs. A perineural window was created in all cases. Motor recovery up to 16 weeks postoperation was tested with the grasping test. No recovery of motor function was evident after end-to-side neurorrhaphy of the median nerve to the antagonistic radial nerve, whereas six of eight rats with end-to-side neurorrhaphy to the agonistic ulnar nerve achieved 367 g +/- 47 g grasping power as compared to 526 g +/- 6 g in end-to-end coapted control animals. No significant difference in flexor digitorum sublimus-motor nerve conduction velocity was found among all three groups. Radial nerve stimulation produced simultaneous contraction of both extensor and flexor muscles of the lower arm that disabled any coordinated movement of the paw. Histology (toluidine blue, acetylcholinesterase-stain) showed multiple regenerated (motor)-axons distal to the coaptation site in the median nerve. Reinnervation of the median nerve solely by the respective donor nerve was demonstrated by a retrograde double labelling technique. These results show that averaged 70% muscle power as compared to end-to-end neurorrhaphy with well coordinated muscle function can be achieved by axonal sprouting through end-to-side neurorrhaphy if an agonistic nerve is used as donor nerve. However, satisfying results are unpredictable. Antagonistic nerves show the ability to induce axonal regeneration, but no useful function can be expected.

Anastomosis, Surgical↗
PubMed2000

Nerve transfer to the median nerve using parts of the ulnar and radial nerves in the rabbit--effects on motor recovery of the median nerve and donor nerve morbidity.

In this study, motor re-innervation of the median nerve by transfer of one-third, one-half, and two-thirds of either the agonistic ulnar nerve or the antagonistic radial nerve was investigated in both extremities of 20 rabbits. Recipient median nerve: Muscle contraction force of the flexor digitorum sublimus muscle after a one-third and a one-half of the ulnar nerve transfer achieved an average of 75 and 97% muscle power respectively as compared to conventional end-to-end neurorrhaphy. Muscle contraction force after one-third or one-half of the radial nerve transfer was significantly lower (36%). Donor nerves: Extensor carpi radialis muscle or flexor carpi ulnaris muscle contraction force 6 months postoperatively demonstrated a significant decrease after a one-half ulnar nerve and a two-thirds ulnar or radial nerve transfer, but not after a one-third transfer of either radial or ulnar nerves. Histologically, the number of axons in the re-innervated median nerve and both donor nerves distal to the coaptation site seemed to follow variable patterns. It was concluded that in the rabbit use of one-third of the agonistic ulnar nerve for re-innervation of the median nerve results in useful motor recovery with negligible donor site morbidity. Clinically, this technique may offer an alternative option for proximal nerve injuries or for free functioning muscle transplantations.

Animals↗
PubMed2000

Indications and limitations of angiography before free-flap transplantation to the distal lower leg after trauma: prospective study in 36 patients.

The necessity for routine angiography in evaluation of the vasculature of recipient legs prior to microsurgical free-tissue reconstruction still remains controversial. This prospective study was designed to determine the indications and limitations of angiography pertinent to this issue. The protocol consisted of palpation of dorsalis pedis and posterior tibial artery pulsation and lower-limb angiography prior to surgery, as well as intraoperative observation of the posterior tibial, anterior tibial, and peroneal arteries. Thirty-six patients were included who were treated from November, 1993 to December 1998. In five patients either the posterior tibial pulse (1), the dorsalis pedis pulse (3), or both pedal pulses, including the popliteal pulse (1) were not palpable preoperatively. These clinical findings correlated with the vascular lesion images on angiography. In two patients, pedal pulse palpation could not clearly be evaluated because of the injury. Among the 29 patients with both pedal pulses palpable, three patients angiographically presented an injury of the peroneal artery, and one patient a pseudoaneurysm of the anterior tibial artery. In none of the cases with at least one palpable pedal pulse (33), did preoperative angiography add relevant information which led to a plan change in the free-flap transfer. However, in two cases, severe scarring and fibrosis required an intraoperative change of the recipient vessel in one case, and a change of the anastomosis level and use of a vein graft, in the other case, although the angiography had demonstrated normal vascularity in both. The authors conclude that preoperative angiography is indicated only when both pedal pulses are not palpable, and that normal preoperative angiography does not guarantee the presence of vessels suitable for anastomosis.

Adolescent↗
PubMed2000

Role of the target in end-to-side neurorrhaphy: reinnervation of a single muscle vs. multiple muscles.

The authors examined the effects of end-to-side neurorrhaphy for reinnervation of the musculocutaneous nerve (Group A) which innervates the biceps muscle, compared to reinnervation of the median nerve which innervates multiple muscles in a rat model. Additionally, end-to-end neurorrhaphy to the musculocutaneous nerve using one-third of the median nerve (Group B) was investigated. End-to-end coaptation of the musculocutaneous nerve served as a control (Group C). In a grooming test, the biceps muscle function in Group A animals demonstrated a slower but nearly similar good recovery to Groups B and C. Biceps muscle contraction force investigated after 24 weeks demonstrated no statistically significant differences among all groups. In Groups A and B, no significant impairment of the donor median nerve function was found in a grasping test and the muscle contraction force of the flexor carpi radialis muscle, and histologic evaluation of the musculocutaneous nerve showed multiple regenerated axons distal to the coaptation site. Retrograde double-labeling in Group A animals showed reinnervation of the musculocutaneous nerve by median nerve axons located at the coaptation site. These results validate that end-to-side neurorrhaphy to a nerve innervating a single muscle is more efficient than to a nerve innervating multiple muscles, as demonstrated in an earlier study. The reason for this phenomenon is most likely that all sprouting axons are directed toward one target rather than toward multiple targets, with the latter situation resulting in a smaller number of axons and a variable distribution of axons per target. Since donor nerve sprouting axons were observed at the coaptation site, a relevance of the selected site for end-to-side neurorrhaphy is suggested. Both end-to-side neurorrhaphy and end-to-end neurorrhaphy, using one-third of the median nerve, led to useful functional recovery in this rat model, if an agonistic donor nerve is employed.

Anastomosis, Surgical↗
PubMed2000

Free flap to the arteria peronea magna for lower limb salvage.

A 36-year-old woman sustained an amputation of her right leg at the thigh level and a degloving injury of her left foot and ankle region in an accident during a suicide attempt. Primarily, her left foot was covered with a split skin graft, resulting in a soft-tissue defect at the medial malleolus and at the calcaneus bone. Reconstruction was planned with a free latissimus dorsi muscle flap. Preoperative examinations revealed an arteria peronea magna with a hyperplastic peroneal artery solely providing arterial blood supply to the foot. The arteria peronea magna divided into two branches proximal to the upper ankle joint, replacing the dorsal pedis artery and the medial plantar artery. Tibial posterior and tibial anterior arteries were hypoplastic-aplastic. Microvascular end-to-end anastomoses of the flap vessels to the medial branch ("medial plantar artery") of the arteria peronea magna and its concomitant vein at the medial malleolar bone level were successfully performed. The postoperative course was uneventful. Four weeks postoperatively, the patient started walking assisted by a prosthesis on her right thigh stump. This experience demonstrates that even in a case of arteria peronea magna, free flap surgery for lower limb salvage is a reliable and worthwhile method.

Adult↗
PubMed2000

Flap perfusion after free musculocutaneous tissue transfer: the impact of postoperative complications.

In a previous study, the authors found persistence of pedicle blood flow up to 10 years after uncomplicated free latissimus dorsi transfer. In this study, the impact of postoperative complications (hematoma, thrombosis, infection) and successful surgical revision was tested. Since 1982, more than 1200 free tissue transfers have been performed at the authors' institution (Hannover Medical School). Of these, the authors selected two groups of 30 patients each who had received a free latissimus dorsi transfer to the lower leg without microsurgical nerve coaptation for wound coverage. All patients included in this study were carefully selected for clinical homogeneity, with one difference: group I comprised patients who had no postoperative complications after free latissimus dorsi transfer. Group II included only patients with major postoperative complications after the procedure. All flaps in group II survived after successful surgical revision. The arteries, which nourished the lower leg, were visualized and documented by means of a duplex scanner in both groups. Three different time intervals were chosen for measurements of blood flow: 4 to 6 months (groups I.I and II.I), 4 to 6 years (groups I.II and II.II), and 8 to 10 years (groups I.III and II.III). Quantitative measurements of local flap perfusion in milliliters per minute per 100 g tissue were performed by means of the hydrogen clearance technique. In each patient, a total of nine measurements was performed in three phases: phase A, before closing the vascular pedicle by manual compression (n = 3); phase B, with a closed pedicle (n = 3); and phase C, after releasing the vascular pedicle from manual compression (n = 3). Each measurement took approximately 10 minutes. One hundred percent closure of each pedicle in phase B was confirmed by the duplex scanner. Furthermore, all patients were monitored both clinically and by means of the hydrogen clearance technique during phase B for adequate blood supply to the lower leg. Lower leg perfusion showed no statistical differences for phases A, B, and C in all groups of patients. In group I, no statistical differences in local flap perfusion were encountered for phases A and C. In phase B, however, a statistically significant (p < 0.01) complete extinction of local flap perfusion was registered in all patients of group I at the site of the flap's skin paddle. In group II, however, persistent flap perfusion was registered during phase B in up to 50 percent of cases in one subgroup (II.III). No statistically significant alterations of local blood flow were registered in the surrounding tissue of group II during phases A, B, and C. Patients with thrombosis of the venous anastomosis (n = 7) seemed to have the highest incidence of loss of autonomous blood supply through the vascular pedicle (5 out of 11 cases). No inconstant results were found during the repetitive measurements (n = 3) for each patient in each phase. After uncomplicated free tissue transfer, the flap's intact vascular pedicle seems to play an important role in permanent flap survival up to 10 years after the procedure. Postoperative complications after free tissue transfer with successful surgical revision, especially venous thrombosis of the vascular anastomosis, may lead to loss of vascular flap autonomy over time.

Adult↗
PubMed1999

Effects of insulin-like growth factor-1 in motor nerve regeneration after nerve transection and repair vs. nerve crushing injury in the rat.

Despite highest standards in nerve repair, functional recovery following nerve transection still remains unsatisfactory. Non-specific re-innervation of target organs are regarded as one reason for a poor functional outcome. Insulin-like growth factor-1 (IGF-1) has demonstrated promoting effects on sciatic nerve regeneration after crushing injury. Similarly, IGF-1 has shown a direct inductive effect on motoneuron growth associated protein-43 (GAP-43) which is believed to play a role in axon guidance during development. Based on this fact we have examined the trophic effects of recombinant human IGF-1 on peripheral motor nerve regeneration following transection and epineural repair in rats median nerve. RhIGF-1 (0.5 mg/kg/rat) was administered subcutaneously to the neck of the repaired side for 14 days postoperation. Accuracy of re-innervation of the flexor carpi radialis muscle motoneuron pool was studied by sequential retrograde double labelling technique. Motor recovery was tested with the grasping test. No significant differences between experimental and control animals in accuracy of re-innervation and in recovery of muscle power could be demonstrated. Non-specific re-innervation of the flexor carpi radialis muscle was found in 23.2% in the experimental group and in 24.2% in the control group. These results demonstrate that systemically applied rhIGF-1 failed to improve functional motor recovery after nerve transection and repair in the rat as it was demonstrated after nerve crushing injury in several studies. Furthermore, systemically applied IGF-1 did not improve accuracy of re-innervation after axotomy and repair in adult rats.

Animals↗
PubMed1999

[Supra-fascial elevated free forearm flap--indications, surgical technique and follow-up examination of the donor site defect].

From March 1995 to May 1997, 66 free radial forearm flaps were used for orofacial reconstructions. All flaps were elevated following the suprafascial technique. Donor-site closure was performed with split-thickness skin grafts in 54 cases, and with full-thickness skin grafts in 12 patients. Investigations after six months included grip strength, pulp-to-pulp pinch strength, range of motion as compared to preoperative values, aesthetical self-assessment, cold intolerance, and dysesthesias. The latter evaluation could be performed in 42 patients, whereas the complete follow-up protocol included 36 patients. Primary wound healing with immediate complete take of skin grafts was achieved in 93.9%. Grip strength and pulp-to-pulp pinch strength showed no decrease postoperatively. An impairment of range of motion of the wrist was observed in 2.8%. There was no cold intolerance. Aesthetical outcome was rated as good or fair in 97.3%. Slight numbness distally to the donor-site was found in 59.5%. The results of this prospective study show a superiority of suprafascial elevation of the radial foream flap as compared to the classic elevation technique, particularly in a higher rate of primary wound healing, thus avoiding impairment of range of motion and strength of the donor hand.

Adult↗
PubMed1999

Routine donor leg angiography before vascularized free fibula transplantation is not necessary: a prospective study in 120 clinical cases.

To evaluate the value of routine preoperative angiographies of donor sites, 120 patients with free fibula osteoseptocutaneous flap transplantations were included in this prospective study, which consisted of preoperative evaluation of dorsalis pedis and tibial posterior artery pulsation and angiographies of the donor legs (120 patients) and contralateral legs (111 patients). Both pedal pulses were palpable in 114 patients, and only one pulse was palpable in six patients. The respective nonpalpable foot pulses were detectable with pencil Doppler in five patients, but they were not detectable in one patient. Intraoperatively, the latter patient had a relatively hypertrophied peroneal artery as compared with both the tibial posterior and tibial anterior arteries. The angiographic result was arteria peronea magna. The other five patients showed intraoperatively and angiographically normal-sized major arteries of the lower leg. In three patients with normal pedal pulses, hypoplasias of either the tibial anterior or tibial posterior arteries were found intraoperatively. These findings corresponded with the angiographical results. In all patients (n = 119), except one with peroneal artery hemangioma, free osteoseptocutaneous fibula flap was harvested from the originally planned leg without subsequent sequelae to the respective donor leg. In 231 leg angiographies, only 7 cases (3 percent) with abnormalsized major lower leg arteries were described. The diagnoses in these cases were hypoplasia of either the tibial posterior or tibial anterior artery (4 cases), arteria peronea magna (2 cases, one of which was a false positive), absence of peroneal artery combined with hypoplastic tibial posterior artery (1 case), and hemangioma of the peroneal artery (1 case). From this prospective study, it was determined that routine preoperative angiography of the donor leg before fibula transplantation is not justified. It does not add relevant new information about donor leg vascularity, provided that the clinical evaluation of the pedal pulses is well conducted. The only two conditions that may require a preoperative donor leg angiography are abnormal pedal pulses or significant previous lower leg trauma.

Adolescent↗
PubMed1999

Donor site morbidity after suprafascial elevation of the radial forearm flap: a prospective study in 95 consecutive cases.

From March of 1995 to November of 1997, 95 free radial forearm flaps for orofacial reconstructions were performed and included in this prospective study of donor site morbidity. All flaps were elevated using the suprafascial dissection technique. Donor site closure was performed with either split-thickness skin grafts (64 cases) or full-thickness skin grafts (31 cases). Among the 95 flaps, there were two complete flap losses and one partial flap loss because of arterial thrombosis. One orocutaneus fistula was successfully treated with a pedicled pectoralis major flap. At the donor site, the rate of complete take of skin graft was 94 percent in 95 patients. Functional and aesthetic results evaluated at least 6 months postoperatively in 50 patients revealed no significant change in grip power, pulp-to-pulp pinch power, or wrist movement in the complete skin graft take group (45 cases), whereas in the partial skin graft failure group (5 cases), both grip power and movement were significantly decreased. There was no remarkable cold intolerance in any of the 50 patients. Critical evaluations of sensory change revealed numbness distal to the donor site in 54 percent of the patients. However, dysesthesia was usually mild and improved spontaneously as time passed. Aesthetic outcome was rated as good or fair in 98 percent of the cases. The results of this prospective study show that suprafascial elevation of the radial forearm flap is superior to the classic elevation technique, particularly with regard to a higher rate of immediate complete take of skin grafts, thus avoiding impairment of range of motion and strength of the donor hand.

Adult↗
PubMed1999

Reconstruction of bilateral metacarpal hands with multiple-toe transplantations.

Bilateral metacarpal hands, if not treated properly, leave a patient without prehensile ability in both hands. Since 1990, six patients with bilateral metacarpal hands caused by accidents have undergone reconstruction with multiple-toe transplantations. Four or five toes were used for each patient, with a total of 27 toes transplanted to the hands. There was no toe loss. One nonunion in a middle-finger reconstruction was treated successfully with bone grafting. Secondary operations for functional improvement included one joint fusion and one flexor tendon tenolysis. Only one patient required excision of a plantar callus 42 months postoperatively, whereas the other five patients reported no major donor-site problems in an average 57 months of follow-up time. The six patients continue all their daily activities independently. Although their jobs were changed, all adult male patients were able to return to regular work. Principles of reconstruction to achieve satisfying prehensile function combined with minor donor-site morbidity in bilateral metacarpal hands include an adequate soft-tissue coverage before toe transplantations, selection of digits to be reconstructed based on functional and individual requirements, selection of toes and number of toes to be harvested based on consideration of usefulness for the hands and of foot morbidity, and consideration of thenar function in planning the sequence of transplantations. In conclusion, given thorough planning, multiple toe-to-hand transplantations can provide adequate prehensile function in reconstructed bilateral metacarpal hands with acceptable donor-site morbidity.

Adult↗
PubMed1999

Combined third and fourth toe transplantation.

Multiple toe transplantation has been established as an effective technique for restoring prehensile ability in the metacarpal hand. The combined third and fourth toe transplant is a new toe transplant that has been developed for bilateral metacarpal hand reconstruction. Since 1991, the combined third and fourth toe transplant was added to the armamentarium of toe transplants for metacarpal hands, although its role in metacarpal hand reconstruction has not been described previously. This article introduces the indications for combined third and fourth toe transplant, outlines relevant vascular anatomy, and discusses technical considerations pertaining to toe harvest and transplantation.

Adult↗
PubMed1999

Strategies in multiple toe transplantation for bilateral type II metacarpal hand reconstruction.

Multiple toe transplantation has been established as an effective means of restoring prehensile function in the metacarpal hand. The attainable outcome, however, must be weighed against potential donor site morbidity. Restoration of prehensile function in bilateral type II metacarpal hands can be achieved by reconstructing three opposable digits in the dominant hand and two opposable digits in the nondominant hand. This article outlines the strategy for optimizing functional outcome and discusses the rationale behind toe selection to reduce donor morbidity.

Adult↗
PubMed1998

Reconstruction of scalp defects with free flaps in 30 cases.

29 consecutive patients treated for reconstruction of various scalp defects with 30 free flaps were reviewed. The scalp defects resulted from accidents (13), electric burns (4), tumour excision (8), chronic osteomyelitis (1), and osteoradionecrosis (1). Secondary reconstructions for cosmetic improvement were performed in 2 patients. The defects involved scalp with bone exposure in 21 patients, and both scalp and calvarium in 8 patients. The average extent of the defects was 130 cm2 (23-420 cm2). Free flaps employed for reconstruction included radial forearm flaps (15), latissimus dorsi muscle flaps (10), medial arm flaps (2), juri flap (1), rectus abdominis muscle flap (1), and scapular flap (1). In 6 cases bone grafts were used for skull reconstruction. Three patients required dura repair. There were two flap failures. Donor-site morbidity was negligible. No local recurrence occurred in 7 tumour cases who are still alive. Secondary procedures (tissue expansion, debulking) were performed in 6 patients. The authors recommend selection of reconstructive options for scalp defects according to their aetiology, localisation, and duration of treatment, whereas the size of the defect dose not seem to be the most important determinant. They conclude that a free flap procedure is appropriate for scalp reconstruction in trauma, osteomylitis, and osteoradionecrosis cases, and following radical resection of malignant tumours.

Accidents↗