Necrotizing fasciitis caused by Vibrio vulnificus: epidemiology, clinical findings, treatment and prevention.

Necrotizing fasciitis is a soft-tissue infection with a high risk of fatality. Infection with Vibrio vulnificus can lead to development of necrotizing fasciitis and primary septicemia, and occurs mostly in immunocompromised host-associated diseases such as hepatic disease, diabetes mellitus, chronic renal insufficiency, and adrenal insufficiency. Early recognition and treatment of the infection, which are unclear, are vital to patient welfare. We studied the disease epidemiology and reviewed the prognosis and clinical features of patients treated using our developed protocol. Clinical manifestations and outcomes were retrospectively analyzed for 67 patients with V. vulnificus-mediated necrotizing fasciitis and sepsis. All patients who had contacted seawater or raw seafood with positive culture for vibrio were included. Patients were divided into two groups based on the timing of first fasciotomy and injury; within 24 h (group A) and beyond 24 h (group B). Twenty-three of the 67 patients (40%) had hepatic disease, 17 (25.4%) had chronic renal insufficiency, and 12 (17.9%) exhibited adrenal insufficiency. The most common site of infection was the upper extremity (74.7%). Group B presented with more clinical symptoms including fever (p = 0.02), hemorrhagic bullae (p < 0.0001), and shock (p = 0.007). Group A patients exhibited enhanced survival compared to group B (in hospital mortality: 4.9% vs. 23%; p = 0.005). We conclude that early and appropriate diagnosis for V. vulnificus infection should be made, especially in patients presenting with atypical clinical findings. Early fasciotomy within 24 h remains the highest priority and decreases the mortality rate.

Secondary procedures following digital replantation and revascularisation.

In this retrospective study, 79 digits of 55 patients received 102 secondary procedures following replantation. We divided the procedures into two groups, occurring before or after 2 months following replantation. The procedures in the early group were mainly for soft tissue coverage (92%), and those in that late group were mainly for tendon (67%) to improve function. Factors associated with higher incidence of early secondary procedures included multiple-finger injury, avulsion or degloving injury and level of injury proximal to zone III in finger replantation (p<0.05). However, younger patients and those with proximal level replantation in fingers had more late secondary procedures (p<0.05). Flexor tenolysis procedure significantly improved the digital function after replantation (p<0.05).

A novel platelet-rich arterial thrombosis model in rabbits. Simple, reproducible, and dynamic real-time measurement by using double-opposing inverted-sutures model.

Though numerous animal thrombosis models have been introduced, an easy, reliable, and reproducible arterial thrombosis model remains a continuing challenge prior to a thrombolytic study. In an effort to evaluate the efficiency of various recombinant thrombolytic agents with specific affinity to activated platelets in vivo, we developed a novel double-opposing inverted-sutures model to create a platelet-rich thrombus in the femoral artery of rabbits. The arteriotomy was done semicircumferentially, and variously sized microsurgical sutures were introduced intraluminally in a double-opposing inverted manner. The animals were divided into three groups according to the double-opposing inverted-sutures used: Group 1 with 10-0 nylon (n=6), Group 2 with 9-0 nylon (n=6), and Group 3 with 8-0 nylon (n=22). The superficial epigastric branch was cannulated with a thin polyethylene (PE) tube for intraarterial administration of the studied thrombolytic agent. The blood flow was continuously measured with a real-time ultrasonic flow meter. Within 2 h of installation of the sutures, there was no thrombus formation in either Group 1 or 2. In Group 3, the thrombosis rate was 91% (20 of 22) under a steady baseline flow (with an average of 12.23+/-2.40 ml/min). It was highly statistically significant with a P-value of .0000743 using Fisher's Exact Test. The averaged time to thrombosis was 21.8+/-9.8 min. The ultrasonic flow meter to record the dynamic real-time measurement of blood flow was a guideline for thrombus formation or dissolution, which was correlated with the morphological findings of stenotic status of the vessel detected by the Doppler sonography. The components of the thrombus were proven to be platelet-rich predominant by histological examination via hematoxylin and eosin (H&E) stain and transmission electron microscopy (TEM). To confirm that the double-opposing inverted-sutures model would be useful for a study of thrombolytic agents, we evaluated the effects of recombinant tissue-type plasminogen activator (rt-PA) and streptokinase-human plasminogen (SK-HPlg). The average time to thrombolysis post rt-PA infusion was 16.0+/-8.2 min and that of SK-HPlg was 79.6+/-23.1, which were similar to the previous reports. In conclusion, the novel double-opposing inverted-sutures (8-0 nylon) model provides a simple, reliable, and reproducible platelet-rich arterial thrombosis model with noninvasive and dynamic real-time measurement. It may be applied in assessing the efficiency of the recombinant thrombolytic agents and offers many advantages of an arterial platelet-rich in vivo thrombosis model.

Reconstruction of the Achilles tendon and overlying soft tissue using antero-lateral thigh free flap.

Reconstruction of combined loss of the Achilles tendon and overlying soft tissue was performed using an antero-lateral thigh free flap in three patients. The cutaneous portion is used to cover the open wound, and a piece of fascia lata is utilised to replace the missing segment of the Achilles tendon. The skin defect ranged from 5 x 2.5 to 7 x 5 cm, and the tendon loss measured from 3.5 to 5.5 cm in length. All of the patients showed satisfactory functional results with a follow-up period from 3 to 9 months. The advantages of the procedure are that: it is a single-staged operation; it promotes rapid healing of the tendo Achilles since the tendon substitute is well vascularised; it is adaptable to a wide range of defect sizes and shapes; it can be performed in the supine position without the need for postural change; and it can restore good contour and causes minimal morbidity at the donor site.

Free anterolateral thigh flap for reconstruction of head and neck defects following cancer ablation.

Thirty-seven consecutive free anterolateral thigh flaps in 36 patients were transferred for reconstruction of head and neck defects following cancer ablation between January of 1997 and June of 1998. The success rate was 97 percent (36 of 37), with one flap lost due to a twisted perforator. The anatomic variations and length of the vascular pedicle were investigated to obtain better knowledge of anatomy and to avoid several surgical pitfalls when it is used for head and neck reconstruction. The cutaneous perforators were always found and presented as musculocutaneous or septocutaneous perforators in this series of 37 anterolateral thigh flaps. They were classified into four types according to the perforator derivation and the direction in which it traversed the vastus lateralis muscle. In type I, vertical musculocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 56.8 percent of cases (21 of 37), and they were 4.83 +/- 2.04 cm in length. In type II, horizontal musculocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 27.0 percent of cases (10 of 37), and they were 6.77 +/- 3.48 cm in length. In type III, vertical septocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 10.8 percent of cases (4 of 37), and they were 3.60 +/- 1.47 cm in length. In type IV, horizontal septocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 5.4 percent of cases (2 of 37). They were 7.75 +/- 1.06 cm in length. The average length of vascular pedicle was 12.01 +/- 1.50 cm, and the arterial diameter was around 2.0 to 2.5 mm; two accompanying veins varied from 1.8 to 3.0 mm and were suitable for anastomosis with the neck vessels. Reconstruction of one-layer defect, external skin or intraoral lining, was carried out in 18 cases, through-and-through defect in 17 cases, and composite mandibular defect in two cases. With increasing knowledge of anatomy and refinements of surgical technique, the anterolateral thigh flap can be harvested safely to reconstruct complicated defects of head and neck following cancer ablation with only minimal donor-site morbidity.

Long-term effects of sensory reeducation following digital replantation and revascularization.

The long-term maintenance of sensory gain following sensory reeducation is still unknown for replanted digits. Ten patients with 18 replanted or revascularized digits, who had received a formal sensory reeducation program for 1.5 years postoperatively, were reevaluated with moving two-point discrimination and Semmes-Weinstein pressure threshold test after discontinuing sensory reeducation for 1 year. Another four patients with seven replanted or revascularized digits, who have never received sensory reeducation after surgery, were also followed up in the same way. After cessation of sensory reeducation, the degree of moving two-point discrimination became significantly worse in the formal sensory-reeducated group (P < 0.05) and significantly improved in the group without sensory reeducation initially (P < 0.05), whereas it showed a nonsignificant change of Semmes-Weinstein threshold both in the group with formal sensory reeducation and without sensory reeducation. Sensory retraining did influence the progressive change of moving two-point discrimination, but not in a parallel way with the Semmes-Weinstein threshold test.

The application of scanning acoustic microscopy in a bone remodeling study.

Scanning acoustic microscopy (SAM) was used in the evaluation of bone remodeling around a cylindrical unicortical defect. SAM is a technique for the nondestructive evaluation of materials, and has only recently been employed as an orthopaedic research tool. The utility of SAM was demonstrated by using it to measure an elastic property known as acoustic impedance. Specifically, the acoustic impedance of bone formed by remodeling around a cylindrical defect was measured. The defects were filled with either a low modulus "void" or rigid inclusion to create various states of stress in the bone in the vicinity of the defect. After six months of implantation of the inclusions in the sheep metatarsal, new bone formation on periosteal and endosteal surfaces about the defect region was observed. These regions of new bone were less stiff and had 18.0 +/- 6.5% lower acoustic impedance than the pre-existing bone in the intracortical region of the metatarsal. There was no difference in the degree of new bone formation about void and rigid inclusions. Both underwent significant adaptational changes in response to the elevated stress about the defect. These changes affected the basic structure of the bone cross-section at the level of the defect and effectively reduced the stress levels about the defect. By using SAM to measure acoustic impedance, it was seen that little internal remodeling occurred in the intracortical region. Hence, the primary mechanism of strain-induced bone remodeling observed in this experimental model was surface remodeling.

Evaluation of the effectiveness of sensory reeducation following digital replantation and revascularization.

Sensory recovery following digital replantation plays an important role in the restoration of hand function. Twelve patients with twenty-four replanted or revascularized digits were randomly selected to enter a program of sensory reeducation, and another 15 patients with 22 replanted or revascularized digits were selected as controls who did not receive sensory reeducation. A moving two-point discrimination and a Semmes-Weinstein pressure threshold test were evaluated for monitoring the sensory recovery. The period of sensory reeducation was 18.83 weeks on average, and the mean follow-up time was 11.94 months. The group that received sensory reeducation significantly improved to a better degree of moving two-point discrimination and Semmes-Weinstein threshold level by both univariate and multiple regression analysis. We suggest that sensory reeducation should be an integral part of the postoperative rehabilitation protocol following digital replantation and revascularization.

Multivariate analysis of factors influencing the functional recovery after finger replantation or revascularization.

A multivariate statistical analysis was utilized to study the influence of the four preoperative (age, mechanism of injury, level of injury, and type of amputation) and one postoperative (rehabilitation) variables on the functional recovery of the replanted or revascularized finger. Statistically significant differences are summarized as follows. The young age group have a better functional recovery due to better sensory recovery than the old age group. The crush injury group have a better functional recovery, with better scores in motion and patient satisfaction, than the avulsion injury group. The middle phalangeal injury group have a better functional recovery, with better score in motion and sensation than the proximal phalangeal injury group. There is no statistically significant difference in functional recovery between the revascularized and replanted fingers, but there is a significantly better sensory recovery in the revascularized finger. The rehabilitation group has a better functional recovery, with better score in motion, subjective symptoms, and patient satisfaction, than the nonrehabilitation group.

Preliminary characterization of bioresorbable and nonresorbable synthetic fibers for the repair of soft tissue injuries.

Preliminary characterizations of two new synthetic fibers were performed to determine their potentials for use in soft tissue scaffolding devices. A slowly bioresorbing random copolymer of dimethyltrimethylene carbonate (DMTMC) and trimethylene carbonate (TMC) was the first fiber evaluated. The second was a nonresorbable high-strength synthetic fiber of highly oriented polyethylene. Their in vitro mechanical behavior was evaluated by loading fibers in uniaxial tension to determine mechanical properties in dry and wet (saline) environments. The polyethylene fiber had a dry strength of approximately 2.0 GPa, an ultimate strain of 3 to 4%, a tangent modulus of 57 GPa, and was not affected by the saline environment. The bioresorbable fiber had a dry strength of approximately 500 MPa, an ultimate strain of 35%, and tangent modulus of 5.4 GPa. The in vitro resorption of the bioresorbable fibers produced a 15% loss in strength over a 10-week period. In vitro cell-fiber compatibility studies were conducted to assay material biocompatibility and fiber substrate efficacy. Fibroblasts proliferated and migrated on both the polyethylene and bioresorbable fibers at rates similar to those previously found for other compatible fibers, thus demonstrating the new materials to be similar in their in vitro biocompatibility profiles. Morphological assessment with SEM also confirmed that these materials were suitable substrates for cell attachment. A rabbit Achilles tendon repair model using oriented polyethylene or bioresorbable fiber tows was evaluated after 12 and 26 weeks of implantation. The mechanical performances of both types of tendon repairs were similar to those found in previous studies using carbon or PET fibers. The polyethylene fibers elicited a low-grade chronic inflammatory tissue response. The bioresorbable fibers were still intact at 26 weeks and remained relatively inert in the host tissue, eliciting a minimal foreign body response.

Mechanical properties of collagen fibres: a comparison of reconstituted and rat tail tendon fibres.

This study involves comparison of the mechanical properties of reconstituted collagen fibres with those of collagen fibres obtained from rat tail tendons. Reconstituted collagen fibres were cross-linked in the presence of glutaraldehyde vapour for 2 and 4 d or using a combination of severe dehydration and carbodiimide treatment. Ultimate tensile strengths for reconstituted fibres cross-linked with glutaraldehyde ranged from 50 to 66 MPa while those cross-linked by severe dehydration and carbodiimide treatment had ultimate tensile strengths between 24 and 31 MPa. Rat tail tendon fibres had tensile strengths that ranged from 33 to 39 MPa. These results indicate that high-strength collagen fibres can be reconstituted in vitro and that these fibres may be useful in repair of dermal, dental, cardiovascular and orthopaedic defects.