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Tim-Mo Chen

Publications and source records attributed to Tim-Mo Chen.

13 recordsLinked to original sources
PubMed2006

The distally based sural fasciomusculocutaneous flap for foot reconstruction.

Finding appropriate soft-tissue to cover a wound located over the middle or distal portion of the foot can be challenging. A distally based sural fasciomusculocutaneous flap including the sural nerve and a midline cuff of the gastrocnemius muscle can be used for this purpose. This flap is designed on the proximal third of the posterior calf and is nourished in a retrograde manner by the lower peroneal septocutaneous perforators, through the vascular axis of the sural nerve to the musculocutaneous perforators of the gastrocnemius muscle. Between October of 2002 and January of 2004, this flap was applied in nine individuals, including four diabetic patients. The skin defects all resulted from trauma, osteomyelitis or chronic ulcer, and combined with bone or tendon exposure. One flap developed distal necrosis. The other flaps survived fully and provided good contour. In our series, diabetes mellitus seemed not to compromise the vascularity of the flap. The distally based sural fasciomusculocutaneous flap is very useful for lower limb reconstruction, particularly for the foot, because of its long vascular pedicle and the availability of the skin portion of the proximal calf based on direct branches between the musculocutaneous perforators and the neurovascular axis of the sural nerve. This is an important variant of the sural neurocutaneous flap and it appears to be a good alternative to free flaps for resurfacing the foot.

Diabetic Foot↗
PubMed2005

The application of new biosynthetic artificial skin for long-term temporary wound coverage.

Temporary dressings protect wounds from desiccation and infection. In our previous study, we used meshed acellular porcine dermis (APD) to enhance wound healing and decrease wound contraction; however, the wounds showed meshed scar. In this study, we produced an artificial skin composed of a cross-linked silicon sheet on the surface of APD which we have called silicone acellular porcine dermis (SAPD). This new artificial skin can protect the wound long enough to promote wound healing either by second intention or covered long enough until cultured epithelium autograft (CEA) or autologous skin graft can be harvested for permanent coverage. We delivered 4 cm x 5 cm full-thickness wound on the back of 350 g Sprague-Dawley rats. Thirty-six rats were divided into two groups. Eighteen rats had SAPD and the other 18 were covered with Biobrane. The wounds were first examined 2 weeks after grafting and followed weekly for an additional 4 weeks to evaluate the wound and study pathological changes by using H.E. and Masson's stains. Wound size was calculated by ruler and analyzed by Student's t-test. At the 2-week inspection, both SAPD and Biobrane showed tight adherence to the wound with no change of wound size. Both the SAPD and Biobrane dermal templates were pink. In the Biobrane-covered group, the wounds contracted soon after the tie-over dressing was removed. Its dermal layer is a layer of thin porcine dermal substance, which was promptly digested by tissue hyaluronidase and provides no real dermal template. In the SAPD-covered group however, the wound size was maintained significantly from third to sixth week after grafting (p<0.001). SAPD was designed with thick epidermal silicone and a well-organized porcine dermis so that it incorporates into the recipient wound. Clinically the silicone layer of SAPD dislodged from APD about 6-7 weeks after grafting and was followed by dermal matrix exposure and infection. In pathological examination, much like a human skin graft, new vessels were found in APD about 1 week after grafting with minimal inflammatory cells infiltrated in the graft and wound. Six weeks after grafting, the collagen of APD incorporated into the wound, showing palisade arrangement and no sign of rejection. In the Biobrane group however, the wounds showed severe inflammation, the porcine dermal matrix was digested and disappeared 3 weeks after coverage. In conclusion, SAPD is a thick biosynthetic artificial skin, which protects the rat wound significantly longer than Biobrane and prevents contraction. We expect that using of SAPD for temporary wound coverage will provide enough time to grow autologous-cultured epithelium or to reharvest skin grafts.

Animals↗
PubMed2005

A co-cultured skin model based on cell support membranes.

Tissue engineering of skin based on collagen:PCL biocomposites using a designed co-culture system is reported. The collagen:PCL biocomposites having collagen:PCL (w/w) ratios of 1:4, 1:8, and 1:20 have been proven to be biocompatible materials to support both adult normal human epidermal Keratinocyte (NHEK) and mouse 3T3 fibroblast growth in cell culture, respectively, by Dai, Coombes, et al. in 2004. Films of collagen:PCL biocomposites were prepared using non-crosslinking method by impregnation of lyophilized collagen mats with PCL/dichloromethane solutions followed by solvent evaporation. To mimic the dermal/epidermal structure of skin, the 1:20 collagen:PCL biocomposites were selected for a feasibility study of a designed co-culture technique that would subsequently be used for preparing fibroblast/biocomposite/keratinocyte skin models. A 55.3% increase in cell number was measured in the designed co-culture system when fibroblasts were seeded on both sides of a biocomposite film compared with cell culture on one surface of the biocomposite in the feasibility study. The co-culture of human keratinocytes and 3T3 fibroblasts on each side of the membrane was therefore studied using the same co-culture system by growing keratinocytes on the top surface of membrane for 3 days and 3T3 fibroblasts underneath the membrane for 6 days. Scanning electron microscopy (SEM) and immunohistochemistry assay revealed good cell attachment and proliferation of both human keratinocytes and 3T3 fibroblasts with these two types of cells isolated well on each side of the membrane. Using a modified co-culture technique, a co-cultured skin model presenting a confluent epidermal sheet on one side of the biocomposite film and fibroblasts populated on the other side of the film was developed successfully in co-culture system for 28 days under investigations by SEM and immunohistochemistry assay. Thus, the design of a co-culture system based on 1:20 (w/w) collagen:PCL biocomposite membranes for preparation of a bi-layered skin model with differentiated epidermal sheet was proven in principle. The approach to skin modeling reported here may find application in tissue engineering and screening of new pharmaceuticals.

3T3 Cells↗
PubMed2005

Free medial sural artery perforator flap for resurfacing distal limb defects.

BACKGROUND: The need for thin flap coverage has increased, especially for contouring or covering shallow defects of distal limbs. The free medial sural artery perforator flap harvested from the medial aspect of the upper calf can be useful for this purpose. METHODS: Between January 2002 and February 2003, we used the free medial sural artery perforator flap for distal limb reconstruction in 11 clinical cases, including four hands and seven feet. This perforator flap is based on the proximal major perforator of the medial sural artery, which can be identified along the axis of the medial sural artery and usually emerges in an area between 6 and 10 cm from the popliteal crease and approximately 5 cm from the posterior midline of the leg. RESULTS: Most of the flaps were safely raised with a single perforator. One flap developed venous congestion during the postoperative course and finally underwent total necrosis. CONCLUSION: The main advantage of the medial sural artery perforator flap is that it only requires cutaneous tissue to achieve better accuracy in reconstructive site, and it preserves the medial gastrocnemius muscle and motor nerve to minimize donor-site morbidity. However, the tedious process of intramuscular retrograde dissection of the perforator and the unsightly scar of the donor region are the major concerns.

Adult↗
PubMed2005

Free medial sural artery perforator flap for ankle and foot reconstruction.

Resurfacing shallow defects over the ankle and foot with an appropriately thin flap is a common but difficult task. This can be accomplished by harvesting the medial sural artery perforator flap from the medial aspect of the upper calf. Based on the musculocutaneous perforator of the medial sural artery, this flap preserves the medial gastrocnemius muscle and avoids unnecessary flap bulkiness. Between January 2002 and February 2004, we used 2 variants of the free medial sural artery perforator flap for ankle and foot reconstruction in 13 patients (10 fasciocutaneous flaps and 3 adipofascial flaps). In these patients, skin defects were combined with bone, joint, or tendon exposure. The main advantage of this flap is that it provides a thin and pliable coverage to achieve better accuracy in the reconstructive site. Other advantages include maintaining the function of the medial gastrocnemius muscle, providing a long vascular pedicle, and avoiding the need to sacrifice major arteries of the leg. The main disadvantages are the tedious process of intramuscular retrograde dissection of the perforator and the unsightly skin graft over the medial calf.

Adult↗
PubMed2005

Distally based sural fasciomusculocutaneous flap for chronic calcaneal osteomyelitis in diabetic patients.

Chronic calcaneal osteomyelitis is a difficult surgical problem, especially in diabetic patients. After aggressive surgical eradication of nonviable soft tissue and infected bone, there will be a large soft-tissue and bony defect. A distally based sural fasciomusculocutaneous flap including the sural nerve and a midline cuff of the gastrocnemius muscle can be useful for covering the defect. This flap is designed on the proximal half of the posterior calf and has an adequate blood supply derived from retrograde perfusion of the vascular axis of the sural nerve to the musculocutaneous perforators of the gastrocnemius muscle. The patency of the peroneal artery should be confirmed by Doppler ultrasound or angiography before surgery. If there are any vascular problems, this flap will not be used to avoid complications resulting from poor flap circulation. This approach has been used for 11 diabetic patients in the past 2 years. All flaps survived completely and all wounds healed uneventfully. The authors found that the flap was reliable and technically simple to design and execute. This 1-stage procedure not only preserves the major arteries of the injured leg but has also proved valuable for filling bony defect and treating bony infection because it provides a well-vascularized muscle fragment. Compared with other tissue transfers, this flap has special characteristics for use on diabetic patients with chronic calcaneal osteomyelitis.

Aged↗
PubMed2004

Painful fat syndrome in a male patient.

Painful fat syndrome or lipoedema is a distinct clinical condition, characterised by bilateral and symmetrical enlargement of the upper and lower leg with tenderness, but excluding the feet. Lipoedema occurs almost exclusively in females, and no male patient has been reported in the literature published in English. We report on an extremely rare presentation of lipoedema in a male patient. A thorough study based on the case history, physical manifestations, and magnetic resonance imaging (MRI) provided valuable clues for a differential diagnosis. Conservative treatment using weight reduction, compression-stocking application, and diuretic therapy was not effective. Tumescent liposuction with postoperative pressure garments provided a satisfactory treatment.

Adiposis Dolorosa↗
PubMed2004

Split calvarial bone graft for chemical burn-associated nasal augmentation.

The nose is the central part of the face, and constitutes the most prominent projection in facial geometry. This report presents five cases that sustained a chemical burn injury with associated facial mutilation resulting from contact with strong acids. The chemical burn affected the nasal architecture after inflicting a burn injury to the face. Applying bone deriving from a split skull procedure for the nasal projection restoration and the augmentation of the dorsal nose is a feasible undertaking, and the overall result appears satisfactory. A retrospective survey of cases admitted to our clinic from January 1999 to December 2001, inclusively was undertaken and is described below. Split calvarial bone graft procedure for the nasal tip projection reconstruction was performed for five patients, all of whom had sustained chemical burns following assault by strong acid. The disfiguration of the nasal anatomical structure was due to healing from deep burn wounds. The tip became blunt and less protruberant following the arising of cicatricial tightness of the surrounding tissue. Strength and resistance to scar contraction are the first considerations for such implantation when attempting to correct the nasal tip projection. The five female patients sustained a severe chemical burn which involved a surface area ranging from 25 to 60% of total body surface area. The facial mutilation was noted simultaneously with the determination of the extent of the burning injury. A severe burn scar is the typical sequel following a deep chemical burn. Nasal tip projection was restored and a nasal dorsum augmentation procedure with a split calvarial bone graft under an "open" method was used. This particular surgical procedure was able to be used in order to improve the nasal tip projection and resist surrounding scar contracture. The three-dimensional surface structure of the face became more prominent subsequent to the administration of this procedure.

Adult↗
PubMed2004

The management of complicated charcoal contact burns involving deep tissues.

This report describes the management of a charcoal burn involving deep tissues at different anatomic sites. The closure of burn wounds should be considered as a functional and cosmetic outcome whenever possible. Our aim should be to get the soft tissue of the early burned wound closed. A satisfactory result can be achieved if both the functional anatomy and the aesthetic outcome can be kept in mind while planning the management.

Adult↗
PubMed2004

Thin split-thickness toenail bed grafts for avulsed nail bed defects.

Avulsed defect of a fingernail bed is a common injury in acute hand trauma. Insufficient management for this type of nail bed avulsion often leads to an irregular and nonadherent nail. The use of thin split-thickness sterile matrix graft from the great toe for immediate replacement of a nail bed defect can regain a smooth, adherent, and normal-looking nail. Between May of 1998 and December of 2001, we used thin split-thickness toenail bed grafts in 13 fingers of 12 patients with avulsed defects of the nail bed. The end results of this technique were excellent and no deformities occurred in the graft donor area. Thin split-thickness toenail bed graft is a good choice for the treatment of acute nail bed avulsion.

Adult↗
PubMed2004

Sensate first dorsal metacarpal artery flap for resurfacing extensive pulp defects of the thumb.

Finding an appropriate soft-tissue grafting material to close a wound located over the distal phalanx of the thumb, especially the pulp region, can be a difficult task. A sensate first dorsal metacarpal artery flap, mobilized from the dorsum of the adjacent index finger and used as an island pedicle skin flap, can be useful for this purpose. The pedicle includes the ulnar branch of the first dorsal metacarpal artery, the dorsal veins, and the cutaneous branch of the radial nerve. Although this tiny artery is anatomically variable, safe dissection can be achieved by including the radial shaft periosteum of the secondary metacarpal bone and the ulnar head fascia of the first interosseous muscle. This approach has been used for 8 individuals with extensive pulp defects of the thumb over the past 3 years. Skin defects in all patients were combined with bone, joint, or tendon exposure. All flaps survived completely. This 1-stage procedure is reliable and technically simple. It provides sensate coverage to the pulp of the thumb but also avoids nerve repair or more complicated microsurgery.

Adult↗
PubMed2002

The distally based lesser saphenous venofasciocutaneous flap for ankle and heel reconstruction.

Finding an appropriate soft-tissue grafting material to close a wound located over the ankle and heel can be a difficult task. The distally based lesser saphenous venofasciocutaneous flap mobilized from the posterior aspect of the upper leg, used as an island pedicle skin flap, can be useful for this purpose. The vascular supply to the flap is derived from the retrograde perfusion of the accompanying arteries of the lesser saphenous vein. These arteries descend along both sides of the lesser saphenous vein to the distal third of the leg, either terminating or anastomosing with the septocutaneous perforators of the peroneal artery. Between February of 1999 and March of 2001, four variants of this flap were applied in 21 individuals, including 11 fasciocutaneous, five fascial, three sensory, and two fasciomyocutaneous flaps. Skin defects among all patients were combined with bone, joint, and/or tendon exposure. The authors found that the flap was reliable and technically simple to design and execute. This one-stage procedure not only preserves the major arteries and the sural nerve of the injured leg, but it also has proved valuable for covering a weight-bearing heel and filling a deep defect, because it potentially provides protective sensation and a well-vascularized muscle fragment. When conventional local flaps are inadequate, this flap should be considered for its reliability and low associated morbidity.

Adult↗