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Biomedical subjects

T M Tsai

Publications and source records attributed to T M Tsai.

At least 19 recordsLinked to original sources
PubMed2004

Primary reconstruction of a degloved hand using multiple toe transfers on a single pedicle and a reversed radial artery flap.

This case study reports one-stage reconstructive surgery on an 18-year-old man who was injured by an industrial roller machine and who presented with a degloved hand. Non-replantable delgloving occurred in all fingers, with the loss of the palmar and part of the dorsal skin. Multiple free contiguous toes were transferred based on a single dorsalis pedis artery pedicle. The artery was anastomosed to a reversed radial artery flap, which was used to cover the palm for primary reconstruction of the degloved hand. Multiple toes were harvested from the same foot, based on a single pedicle, to contain the potential morbidity to one foot, to enable primary reconstruction, and to decrease the length of the operation. The flaps healed well, and the patient demonstrated adequate tripod pinch and key pinch with the transferred toes, with a two-point discrimination of 12 mm at 1-year follow-up. The patient was satisfied with both the appearance and function of the hand and foot.

Accidents, Occupational↗
PubMed2001

Tip streaming from a drop in the presence of surfactants.

Drop breakup in a linear extensional flow is simulated numerically using a nonlinear model for the surface tension that accounts for maximum packing at the interface. Surface convection sweeps surfactant to the drop poles, where it accumulates and drives the surface tension to near zero. The drop assumes a transient shape with highly pointed tips. From these tips, thin liquid threads are pulled. Subsequently, small, surfactant-rich droplets are emitted from the termini of these threads. The scale of the shed drops depends on the initial surfactant coverage. Dilute initial coverage leads to tip streaming, while high initial coverage leads to the tip dropping breakup mode.

Surface-Active Agents↗
PubMed2001

Major upper limb replantation.

Major amputations remain a challenge to the replantation surgeon. Proper patient selection, good surgical skills, and cooperation among the patient, surgeon, and rehabilitation team help achieve a better outcome.

Adolescent↗
PubMed2000

Platelet-activating factor contributes to postischemic vasospasm.

BACKGROUND: The purpose of the present study was to determine if platelet-activating factor is an important mediator that produces vasospasm during reperfusion after ischemia in skeletal muscle. MATERIALS AND METHODS: A vascular isolated cremaster muscle in male Sprague-Dawley rats was coupled with local intraarterial drug infusion as a model to study microcirculation responses to ischemia/reperfusion injury. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Group 1: platelet-activating factor dose response. Group 2: Effects of a cyclooxygenase inhibitor; indomethacin, and a thromboxane synthetase inhibitor, imidazole, on the response to platelet-activating factor. Group 3: Effects of nitric oxide synthesis inhibitor; N(omega)-nitro-L-arginine methyl ester, on the response to platelet-activating factor. Group 4: Effects of a platelet-activating factor receptor antagonist, CV-3988, indomethacin, and imidazole after 4 h of warm ischemia and reperfusion. RESULTS: Intraarterial infusion of platelet-activating factor produced a dose-related but mild vasoconstriction. Pretreatment with indomethacin or imidazole resulted in significant vasodilation actually emanating from platelet-activating factor infusion. Nitric oxide inhibition (with N(omega)-nitro-L-arginine methyl ester) enhanced the vasoconstriction produced by platelet-activating factor. Pretreatment with CV-3988, indomethacin, or imidazole significantly attenuated ischemia/reperfusion-induced vasospasm and capillary no-reflow in the cremaster muscles. CONCLUSIONS: Ischemia/reperfusion-induced vasoconstriction is at least in part mediated by platelet-activating factor and thromboxane A(2).

Animals↗
PubMed2000

Initiation of microvascular protection by nitric oxide in late preconditioning.

The authors hypothesized that nitric oxide is induced by a brief period of ischemia/reperfusion (ischemic preconditioning, IPC) on postoperative day (POD) 1, and that this released nitric oxide is responsible for initiating a delayed microvascular protection against a prolonged period of ischemia in skeletal muscle on POD day 2. The cremaster muscle of male Sprague-Dawley rats underwent 4 hr of ischemia, and then 60 min of reperfusion. IPC consisted of 45 min of ischemia but was done 24 hr before the prolonged ischemia. Local intraarterial infusion of sodium nitroprusside (SNP, a donor of nitric oxide) or Nw-nitro-L-arginine (L-NA, a nonselective nitric oxide synthase antagonist) were also given 24 hr before prolonged ischemia. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Four groups were compared: 1) control; 2) IPC; 3) SNP + sham IPC; and 4) L-NA + IPC. Four hours of ischemia followed by reperfusion created a significant vasoconstriction and capillary no-reflow in the microcirculation of cremaster muscles. These alterations were largely prevented by IPC. Local intraarterial infusion of SNP without IPC created a similar microvascular protection to that induced by IPC alone. In contrast, intraarterial infusion of L-NA prior to IPC eliminated the IPC-induced microvascular protection. In conclusion, in late preconditioning, nitric oxide contributes to the initiation of a delayed microvascular protection against prolonged ischemia in skeletal muscle.

Animals↗
PubMed1999

Late-preconditioning protection is evident in the microcirculation of denervated skeletal muscle.

We investigated whether ischemic preconditioning induces microvascular protection in skeletal muscle at the late phase (after 24 hours) when the same muscles are subjected to prolonged warm global ischemia. The cremaster muscle of the male Sprague-Dawley rat underwent vascular isolation and was subjected to 4 hours of ischemia and 60 minutes of reperfusion. Early preconditioning consisted of 45 minutes of ischemia followed by 15 minutes of reperfusion before prolonged ischemia/reperfusion; late preconditioning also consisted of 45 minutes of ischemia but was done 24 hours (24-hour period of reperfusion) before the prolonged ischemia/reperfusion. Arteriole diameters and capillary perfusion were measured with use of intravital microscopy. Four groups were compared: rats that underwent early preconditioning, their controls, rats that underwent late preconditioning, and their controls. Early and late preconditioning significantly attenuated vasospasm and capillary no-reflow compared with the controls for each. Average arteriole diameter was significantly larger in the rats that underwent late preconditioning than in any other rats; it was also significantly larger in the controls for late preconditioning than in those for early preconditioning. We introduce a model of the rat cremaster muscle that has been isolated from its vascular supply as a useful preparation to study the effects of late preconditioning on microcirculation in skeletal muscle. Late preconditioning provided better microvascular protection than did early preconditioning. The mechanism for this preconditioning protection is being investigated because it should provide a means for therapeutic intervention.

Animals↗
PubMed1999

A comparative analysis of the six-strand double-loop flexor tendon repair and three other techniques: a human cadaveric study.

The ideal zone II flexor tendon repair would be easy to perform, cause minimal scarring, and be strong enough to allow early active motion. A 6-strand loop suture technique devised by the senior author (T.M.T.) was studied in vitro. Forty flexor tendons were harvested from fresh-frozen human hands and divided into 4 groups of 10 tendons each. Each group of tendons was repaired with a specific technique: group 1, the modified Kirchmayr (modified Kessler) technique; group 2, the single-loop 2-strand technique described by Tsuge; group 3, Tsai's double-loop 4-strand modification of Tsuge's technique; and group 4, Tsai's double-loop 6-strand modification of Tsuge's technique. Gap resistance of each repair technique was recorded on a computer using a Differential Variable Reluctance Transducer (MicroStrain, Burlington, VT) and on videotape to record first gap formation, 1-mm and 2-mm gap formation, and maximum load. Statistically significant differences between groups were as follows: at first gap formation between the 2-strand and 6-strand loop suture techniques, and at maximum load between the modified Kessler and 4-strand, modified Kessler and 6-strand, 2-strand and 4-strand, and 2-strand and 6-strand loop suture techniques. The 6-strand double-loop suture technique had a higher tensile strength than the other techniques, as measured in this model at each stage in our experiment. The 6-strand double-loop suture technique simplifies flexor tendon repair. It improves the repair's strength and its resistance to gapping without increasing tendon handling or bulk. This increased repair strength allows us to pursue a more aggressive rehabilitation program.

Biomechanical Phenomena↗
PubMed1999

Cubital tunnel release with endoscopic assistance: results of a new technique.

We evaluated the results of cubital tunnel release with endoscopic assistance. The study included 76 patients (85 elbows); 47 women and 29 men. Nine patients had bilateral procedures. Patients were excluded if they had less than 1 year of follow-up, associated pathology at the elbow to account for the nerve compression, or recurrent cubital tunnel syndrome. Before surgery, cases were categorized by stage of cubital tunnel syndrome according to Dellon's classification: 33 (39%) elbows were classified as mild, 35 (41%) moderate, and 17 (20%) severe. Surgical results were assessed according to a modified Bishop rating system. The mean follow-up period was 32 months (range, 12-52 months). Results were excellent in 42% of the elbows, good in 45%, fair in 11%, and poor in 2%. Recurrence occurred in 3 elbows. There were no serious complications. The results of this study support our recommendation of cubital tunnel release with endoscopic assistance as a safe and reliable technique for the treatment of cubital tunnel syndrome, especially in patients with mild to moderate symptoms.

Adult↗
PubMed1998

Single pedicle vascularized double joint transfer: anatomic study of two models.

This study examined the anatomic structures that communicate between the tibial and fibular digital arteries of the second toe at the distal phalanx to identify a channel for retrograde blood flow from the dominant pedicle to the distal joint flap. We also assessed the feasibility of two models designed to mobilize toe joints to perform single pedicle vascularized double-joint transfer. The continuity of the vascular pathway in both models was demonstrated by microfil injection and angiographic study. The average mobile distance between the PIP joint and the MTP joint was 5.6 +/- 0.6 cm in model I and 5.1 +/- 0.4 cm in model II. The dissection and mobilizing procedures of the neurovascular pedicle are more complicated and extensive in model II than in model I, and the risk of jeopardizing vascularity of the distal joint flap is higher. Both models may be suitable to replace two adjacent metacarpophalangeal (MCP) joints in the hand or two nonadjacent MCP joints (excluding the thumb) separated by no more than one normal metacarpal.

Arteries↗
PubMed1998

Major replantation versus revision amputation and prosthetic fitting in the upper extremity: a late functional outcomes study.

The functional outcomes of amputated arms that were either replanted or had a prosthesis were compared. In addition, factors that influenced the functional outcome of replants were evaluated. The Carroll test was used to evaluate functional capacity of 22 successful upper extremity replantations at or proximal to the wrist as well as 22 amputees (at similar levels) fitted with a variety of prosthetic devices. The outcome was excellent or good in 8 (36%) replanted limbs. This proportion was statistically higher than those grades in the prosthetic group. When the groups were more closely matched (adults with below elbow injuries), the replantation group had 6 (50%) good or excellent outcomes and the prosthetic group had none. An analysis of covariance of the replantations demonstrated a statistical association between a better outcome in younger patients with more distal injuries. This study indicates that replantation produces superior functional results compared with amputation and a prosthesis.

Adolescent↗
PubMed1998

Ischemic preconditioning versus intermittent reperfusion to improve blood flow to a vascular isolated skeletal muscle flap of rats.

OBJECTIVES: We investigated whether intermittent restoration of blood flow just before reperfusion after ischemia could create beneficial effects similar to ischemic preconditioning, which involves intermittent stoppage of blood flow just before ischemia. METHODS: Male Sprague-Dawley rats were prepared with vascular isolated cremaster muscles, then subjected to 4 hours of ischemia and 60 minutes of reperfusion. Arteriole diameters and capillary perfusion were measured by using intravital microscopy. Four groups were used: (1) untreated, (2) ischemic preconditioning (IP), (3) intermittent reperfusion (IR), and (4) ischemic preconditioning plus intermittent reperfusion (IP+IR). RESULTS: Our results showed that IP significantly attenuated both ischemia/reperfusion-induced vasospasm and capillary noreflow. IR was effective in attenuating vasospasm in terminal arterioles. However, IR alone was unable to significantly attenuate capillary no-reflow. Combining both IP and IR achieved the best results. CONCLUSION: Our results suggest both ischemic preconditioning and intermittent reperfusion are useful techniques for attenuating ischemia/reperfusion injury.

Animals↗
PubMed1996

Functional outcome of patients with salvageable limbs with grades III-B and III-C open fractures of the tibia.

Numerous reports list predictive criteria to determine whether Gustilio-type tibial III-B and III-C fractures of the tibia are salvageable. What is lacking are long-term reports of comprehensive functional outcome of these severe injuries. We evaluated the functional outcome of patients with our own seven-scale score. Fifty-four patients with 57 types III-B (n = 41) and III-C (n = 16) open tibial fractures sustained between 1980 and 1989 were recalled for evaluation. There were 45 men and 9 women (average age, 28.4 years; range, 4-68 years). Follow-up periods averaged 48.2 months (range, 12-116 months). Salvage rate for the III-B fractures was 75% (n = 31) and for the III-C fractures 37% (n = 6). We conclude that the functional score is a simple and complete method for assessing the functional outcome of patients undergoing limb salvage procedures.

Activities of Daily Living↗
PubMed1996

Vascularized bone grafts for congenital pseudarthrosis of the tibia.

Eight vascularized fibula grafts and two vascularized rib grafts were used for the treatment of 10 Boyd's Type II congenital pseudarthrosis of the tibia. All but one vascularized fibula graft united within 4 months. The two vascularized rib grafts did not unite until receiving a conventional bone graft. Nine spontaneous fractures were seen in four patients; all were subsequently treated successfully with cast or conventional bone graft. Corrective osteotomies were done in two patients. Follow-up averaged 8 years and 5 months (range, 5 years and 1 month to 14 years and 4 months). Average age at end of follow-up was 13 years and 6 months (range, 7 years and 10 months to 20 years and 4 months). After bony union was achieved, shortening of the affected leg averaged 3.8 centimeters, flexion deformity averaged 20 degrees, and valgus deformity averaged 24 degrees. In three patients, whose leg discrepancy averaged 4.9 centimeters, the leg was lengthened at an average patient age of 13 years and 9 months (age range, 11 years and 7 months to 15 years and 2 months). The resulting limb length discrepancy averaged 2.2 centimeters. Vascularized bone grafting is a reliable technique for achieving bony union in congenital pseudarthrosis of the tibia. Residual shortening may be corrected later by limb lengthening.

Adolescent↗
PubMed1996

A neurovascular island flap for volar-oblique fingertip amputations. Analysis of long-term results.

A neurovascular island flap has been developed to reconstruct volar-oblique fingertip amputations. This study analyzes the data collected on 16 patients who were treated with this flap and had at least 2 years follow-up. The average active/passive range of motion was 54/55 degrees at the DIP joint, 96/98 degrees at the PIP joint, and 83/83 degrees at the MP joint. Twelve out of 16 flaps (75%) had two-point discrimination better than 10 mm. Moderate and severe problems included cold intolerance (six patients), hypersensitivity (three patients), stiffness (three patients), and numbness (two patients). Out of the 16 patients treated with this technique, 14 were satisfied with their surgical outcome. In experienced hands, this technique is a safe and reliable method with which to reconstruct volar-oblique fingertip amputations.

Adult↗
PubMed1996

Outcome of digital nerve injuries in adults.

Evaluations of 67 adults with 90 complete digital nerve injuries were made more than 1 year after surgery. Moving and static two-point discrimination was determined on both lateral aspects of the injured and contralateral uninjured digits. Digits with primary repairs in mild crush or saw injuries had significantly worse two-point discrimination compared with digits that had a primary repair of a simple laceration. Furthermore, in mild crush injuries, digits with primary grafting had significantly better results than those with primary repair. Patients under 40 years of age had better two-point discrimination than those over 40. Some overlap innervation from the uninjured side was noted in two of eight digits tested, since sensation of the injured side was completely lost when the uninjured nerve of that digit was anesthetized. These results support the hypothesis that better recovery is obtained if tension is avoided at the nerve repair site in mild crush or saw injuries.

Adolescent↗