Eul Sik Yoon

Vascular complications of hyaluronic acid fillers and the role of hyaluronidase in management

Skin necrosis following the inadvertent arterial injection of hyaluronic acid (HA) is a serious complication. It is not clear whether or not subcutaneous injections of hyaluronidase decrease skin necrosis in HA-induced vascular complications. We had four cases of HA-induced vascular complications, two of which were treated with hyaluronidase the next day. All of the patients had skin necrosis and scarring. We performed an animal study with rabbit ears in which HA filler was injected into the auricular arteries of both ears. Five rabbits each received a subcutaneous injection of 750 IU of hyaluronidase 4 and 24 h after the filler injection. The hyaluronidase-treated ears in the 4-h intervention group had significantly smaller necrotic areas (p<0.05), while the 24-h intervention group had no differences in the area of necrosis. Hyaluronidase reduced the vascular complications of HA fillers when used early, but there was no benefit to hyaluronidase injection after 24 h.

Correlation of high-resolution ultrasonographic findings with the clinical symptoms and electrodiagnostic data in carpal tunnel syndrome

There are several different imaging methods that are helpful in the diagnosis of carpal tunnel syndrome, including traditional radiography, computed tomography (CT), and magnetic resonance imaging (MRI). CT and MRI offer the advantage of providing direct visualization of the structural abnormality of the carpal tunnel and median nerve, but both of these modalities are expensive and time-consuming. Recently, high-resolution ultrasonography has been reported to be effective in the study of the musculoskeletal system. The authors designed a case–control study to assess the diagnostic value of high-resolution ultrasonography. Forty-eight patients, for a total of 96 hands, whose diagnosis was confirmed by self-administered questionnaire and electrodiagnostic tests, underwent high-resolution ultrasonographic studies. The authors compared the sonographic findings with the electromyographic data and the patients’ severity scores on the self-questionnaires. Proximal swelling of the median nerve at the entrance to the carpal tunnel was found to correlate with the nerve conduction data. Also, compression of the median nerve under the transverse carpal ligament was found to correlate with the subjective symptoms. Although ultrasonography is not an ideal method of diagnosis for carpal tunnel syndrome, it may be helpful for estimating the symptom severity and nerve conduction deficit.

Postoperative morphologic analysis of carpal tunnel syndrome using high-resolution ultrasonography.

The authors evaluated the morphologic changes that follow division of the transverse carpal ligament in patients with carpal tunnel syndrome (CTS) using high-resolution ultrasonography. Ten patients, for a total of 20 hands, underwent high-resolution ultrasonographic studies before the operation and 8 months after the operation. They were all diagnosed with bilateral idiopathic CTS. The authors evaluated the configuration of the median nerve and carpal tunnel at 3 different levels of the wrist: the distal radiocarpal joint level, the pisiform level, and the hook of hamate level. The median nerve gained in thickness to a remarkable extent at 2 distal levels after the operation. The change in morphology of the carpal tunnel at these 2 distal levels was obvious, but the cross-sectional area of the carpal tunnel was increased significantly only at the hook of hamate level. The transverse diameters of the carpal tunnel were not significantly changed. As mentioned, the authors found that the median nerve gained significantly in volume at the distal part of the carpal tunnel postoperatively, and the volumetric increase in the carpal tunnel appears to have resulted from an anterior displacement of newly formed transverse carpal ligament, rather than from a widening of the bony carpal arch.

A prospective study of the anatomic variations of the median nerve in the carpal tunnel in asians

&NA; A prospective study of anatomic variations of the median nerve and its relationship to the surrounding structures was performed of 354 consecutive operations in 192 patients with carpal tunnel syndrome at Korea University Anam Hospital from July 1995 to September 1997. A total of 184 patients were women and 8 patients were men. A total of 162 patients were bilateral and 30 were unilateral. Regarding the course of the motor branch, the extraligamentous type was most common (96.1%, 340 patients). A total of 81.1% of patients (N = 287) had the origin of the motor branch at the radial side of the median nerve (or radial one third), and 17.2% of patients (N = 61) had the origin of the motor branch at the anterior portion of the median nerve. Of these 61 patients, 30 patients (49.1%) were of the preligamentous type. Only one motor nerve branch was found in 89.5% of patients (N = 317), and multiple branches were found in 10.5% of patients. As a result of the comparison between two hands when both hands were operated, the origin and number of motor branches and their courses were identical in most patients (>60%). Hypertrophy of the flexor pollicis brevis was found in 8.5% of patients (N = 30), hypertrophy of the palmaris brevis was found in 4.2% of patients (N = 15), absence of the palmaris longus was discovered in 0.6% of patients (N = 2), existence of the median artery was found in 0.6% of patients (N = 2), and high division of the median nerve rejoining with the thenar motor nerve was found in 0.3% of patients (N = 1). Clearly, the anatomy of the carpal tunnel in Koreans is somewhat different, in part, from the results obtained from studies of whites, but overall results are not significantly different. These results can help obtain a better surgical outcome and complete decompression of the median nerve during operation while preventing inappropriate or inadvertent injury to the motor branch of the median nerve in Koreans. Ahn DS, Yoon ES, Koo SH, Park SH. A prospective study of the anatomic variations of the median nerve in the carpal tunnel in Asians. Ann Plast Surg 2000;44:282‐287

In Vivo Evaluation of Mixtures of Uncultured Freshly Isolated Adipose-Derived Stem Cells and Demineralized Bone Matrix for Bone Regeneration in a Rat Critically Sized Calvarial Defect Model

Although many studies have suggested that human adipose tissue contains pluripotent stem cells, a few reports are available on stromal vascular fraction (SVF). In the present study, we evaluated the bone formation capacities of SVF. We implanted uncultured freshly isolated adipose-derived stem cells combined with demineralized bone matrix (DBM) to induce bone regeneration in a critically sized rat calvarial defect model. We used DBM (DBX(®)) and/or poly(70L-lactide-co-30DL-lactide) copolymer PLA as a scaffold. Fifty white rats were randomized to 5 different groups (n=10): (1) control, (2) DBM, (3) DBMu2009+u2009SVF, (4) DBM + PLA, and (5) DBM + PLAu2009+u2009SVF groups. After acquiring SVF, an 8-mm critically sized calvarial defect was made in each rat. Specimens were harvested at 8 weeks postimplantation and evaluated radiographically and histologically. New bone formation was qualified by hematoxylin and eosin staining and anti-osteocalcin antibody (OC4-30) immunostaining of calvarial sections. Amounts of mineralization were determined by radiodensitometric analysis. In gross appearance, the DBM +u2009SVF and DBM + PLA +u2009SVF groups showed more abundant bone formation than the other groups. Radiodensitometric evaluations revealed that significant intergroup differences were observed according to the Kruskal-Wallis (rank) test (P=0.030<0.05). The 5 groups show different amounts of filling of bone defects (control: 13.48%; DBM: 39.94%; DBM +u2009SVF: 57.69%; DBM + PLA: 24.86%; DBM + PLA +u2009SVF: 42.75%). Histological evaluation revealed that there was abundant new bone formation in the DBM +u2009SVF and DBM + PLA +u2009SVF groups. It was found that undifferentiated adipose-derived stem cells in the form of SVF induced new bone formation in rat calvarial defects. Accordingly, SVF offers a practical, promising candidate for regenerative tissue engineering or cell-based therapy.

Advantages of the presence of living dermal fibroblasts within restylane for soft tissue augmentation.

For the elimination of facial wrinkles and skin contour defects, injectable filler substances composed of commercially prepared nonanimal stabilized hyaluronic acid (Restylane) are now widely used. Although this method of suspension has been shown to be relatively safe and convenient, varying degrees of resorption have required repeated percutaneous injections. This study was undertaken to evaluate the feasibility of Restylane, which is a modified hyaluronic acid, combined with cultured human dermal fibroblasts, to enhance the longevity of injected implants. The histologic changes of the injected implants were also evaluated. For the test group, fibroblasts from the dermis of healthy adults were isolated and cultivated. The cultured fibroblasts were measured with a hemocytometer. Five × 105 fibroblasts suspended in 200 &mgr;l of Dulbecco phosphate-buffered saline (DPBS) were then dispersed in 200 &mgr;l of Restylane to form a 400-&mgr;l human fibroblast–Restylane mix. For the control group, 200 &mgr;l of DPBS without fibroblasts were mixed with 200 &mgr;l of Restylane. These implants were subcutaneously injected into the back of an athymic nude mouse at 6 sites, the 3 left sites composing the control group and the 3 right sites composing the test group. Twelve nude mice were injected for a total of 36 injections per group. The nodular swellings that resulted from the injections were excised to include skin beyond the swelling points down to the panniculus carnosus layer using 5-mm punches, and the weights were measured at 1, 2, 4, 8, 12, and 16 weeks after the injections. Histologic comparisons were also performed to confirm the presence of human collagen in the fibroblast-mixed Restylane group using immunohistochemical study with antihuman collagen type I polyclonal antibody. The mean weight of the control group nodules decreased throughout the examination period. The mean weight at the 16th week was 60% of the weight at the first week. On the other hand, the mean weight of the test-group nodules decreased only over the first 2 weeks. Beyond 2 weeks, there was no further significant weight change. The mean weight at the 16th week was 91% of the weight measured at the first week. Histologic examinations of the control group exhibited negative immunohistochemical staining for human collagen at each examination period. The test group exhibited positive staining after 2 weeks, indicating the presence of human collagen. These results indicate that Restylane mixed with cultured human dermal fibroblasts may be successfully injected as living grafts for long-term retention of implants.

Facial Soft Tissue Augmentation using Autologous Fat Mixed with Stromal Vascular Fraction

Background Autologous fat grafting evolved over the twentieth century to become a quick, safe, and reliable method for restoring volume. However, autologous fat grafts have some problems including uncertain viability of the grafted fat and a low rate of graft survival. To overcome the problems associated with autologous fat grafts, we used uncultured adipose tissue-derived stromal cell (stromal vascular fraction, SVF) assisted autologous fat grafting. Thus, the purpose of this study was to evaluate the effect of SVF in a clinical trial. Methods SVF cells were freshly isolated from half of the aspirated fat and were used in combination with the other half of the aspirated fat during the procedure. Between March 2007 and February 2008, a total of 9 SVF-assisted fat grafts were performed in 9 patients. The patients were followed for 12 weeks after treatment. Data collected at each follow-up visit included clinical examination of the graft site(s), photographs for historical comparison, and information from a patient questionnaire that measured the outcomes from the patient perspective. The photographs were evaluated by medical professionals. Results Scores of the left facial area grafted with adipose tissue mixed with SVF cells were significantly higher compared with those of the right facial area grafted with adipose tissue without SVF cells. There was no significant adverse effect. Conclusions The subjective patient satisfaction survey and surgeon survey showed that SVF-assisted fat grafting was a surgical procedure with superior results.

Enhancement of bone regeneration using osteogenic-induced adipose-derived stem cells combined with demineralized bone matrix in a rat critically-sized calvarial defect model.

INTRODUCTIONnHuman adipose tissue contains pluripotent stem cells that are similar to bone marrow-derived stem cells. The present study examined whether osteogenic induced adipose-derived stem cells (ASCs) could enhance the osteogenic capacity of demineralized bone matrix and accelerate bone formation in a rat critically-sized calvarial defect model.nnnMATERIALS AND METHODSnForty Sprague-Dawley rats were divided randomly into four groups containing 10 rats per each group (Control, 0.05 cc fibrin glue (25 mg/ml) and 0.05 cc thrombin (130 U/ml); DBX, control + 0.2 g DBX�; ASC, DBX + 1 x 105 ASCs/g; iASC, DBX + 1 x 105 osteogenic-induced ASCs/g). After osteogenic differentiation of ASCs, alkaline phosphatase and von Kossa staining were performed each week to determine the extent of differentiation and mineralization. An 8-mm critical size circular defect was made in the calvarial bone of each rat. The specimens were harvested 8 weeks after implantation, and radiographic and histological evaluations were carried out. New bone formation was quantified by radiodensitometric analysis of the calvarial sections. Statistical analysis was accomplished using a Mann-Whitney test and Kruskal-Wallis test at a significance level of P < 0.05.nnnRESULTSnAlkaline phosphatase and von Kossa staining showed that the osteogenic-induced ASCs yielded higher osteogenic differentiation at 3 weeks. The calvarial defect was filled more in the iASC group compared to the other groups, as demonstrated by the gross appearance of the specimen and radiologic evaluation. The mean radiodensity of the control, DBX, ASC, and iASC group was 16.78%, 39.94%, 25.58%, and 51.31%, respectively, and these were significantly different (P=0.034). Histomorphological evaluation confirmed that new bone formation was accelerated and enhanced by the osteogenic-induced ASCs.nnnCONCLUSIONSnASCs produced greater osteogenic differentiation at 3 weeks. Osteogenic regeneration was accelerated and enhanced in vivo with the osteogenic-induced ASCs, compared to undifferentiated ASCs. Osteogenic-induced ASCs are an excellent and promising candidate for regenerative medicine and tissue engineering application.

Analysis of incidences and types of complications in mandibular angle ostectomy in Koreans

A prominent mandibular angle is considered to be unattractive in Asians because it gives the face a square, coarse, and muscular appearance. Asian women desire to have an ovoid, reduced, and slender face by aesthetic mandibular angle resection. Mandibular angle ostectomy has been known to be effective and to satisfy both surgeons and patients. Especially in Korea, it has become as popular as facial bone contouring surgery, which reduces lower facial width. However, a narrow surgical field hinders direct view of the site, making a procedure that is rather difficult to perform. Despite thorough presurgical planning and attention, there can be many complications and unfavorable results. The purpose of this study is to find out the cause of these complications of mandibular angle ostectomy and to develop methods that could prevent these complications from occurring. A questionnaire consisting of 30 questions regarding mandibular angle ostectomy was sent to 40 Korean plastic surgeons. Data from 33 surgeons were analyzed. The total number of operations was 1251, and among them complications appeared in 124 operations, a complication rate of 9.9%. In regards to severe complications, there were 8 cases of subcondyle fracture of the mandible and 6 cases of severe bleeding. Transient facial nerve injury, infection, trismus, asymmetry, undercorrection, overcorrection, secondary angle formation, and entrapped bony segment were also noted as complications. We will report the cause and the prevention methods for each complication.

Transplantation of Adipose Derived Stem Cells for Peripheral Nerve Regeneration in Sciatic Nerve Defects of the Rat

Tissue engineering approaches for promoting the repair of peripheral nerve injuries have focused on cell-based therapies involving Adipose-derived stem cells (ASCs). The authors evaluated the effects of undifferentiated ASCs and of neurally differentiated ASCs on the regenerating abilities of peripheral nerves. We hope that this would demonstrate the feasibility of using adipose derived stem cells for peripheral nerve regeneration and provide clues regarding the use of adipose- derived stem cells. ASCs were isolated and cultured. Then the cells were cultured with neuronal induction agents for neural differentiation. ASCs and neurally differentiated ASCs were transplanted into sciatic nerve defects. After 12 weeks, the number and diameter of the myelinated fibers were measured and nerve conduction study was done. The extent of regeneration of myelinated fibers in the neurally differentiated ASCs transplanted group was greater than that in the ASCs transplanted group or the control group. However, thickness of myelin sheath and diameter of nerve fibers in the ASCs transplanted group were greater than those in the neutrally differentiated ASCs transplanted group or the control group. Nerve conduction study showed good recovery in the neurally differentiated ASCs transplanted groups. Muscles can atrophy and contract if denervation has started. It would be difficult to recover muscle function even if the nerve was reinnervated. Therefore, although neurally differentiated ASCs were found to have a greater functional effect than non-differentiated ASCs, time constraint is important when considering a method of ASCs transplantation.