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Biomedical subjects

C H Shih

Publications and source records attributed to C H Shih.

At least 73 records · Page 4Linked to original sources
PubMed1997

Effect of intermittent cigarette smoke inhalation on tibial lengthening: experimental study on rabbits.

We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. Thirty-eight male rabbits were divided into two groups of 19 animals each. The first group went through intermittent cigarette smoke inhalation, and the second group did not go through intermittent cigarette smoke inhalation. Each animal's right tibia was lengthened 5 mm using an uniplanar lengthening device. Five animals of each group were killed at 4, 6, and 8 weeks postoperatively for biomechanical testing, and one animal of each group was killed at 2, 4, 6, and 8 weeks postoperatively for histologic study. Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of the lengthened tibia of the smoke inhalation group was decreased significantly compared with the non-smoke inhalation group. The mean percent of maximal torque at 4, 6, and 8 weeks were 22.0, 66.3, and 78.6%, respectively, in the smoke inhalation group, whereas the mean percent of maximal torque were 48.0, 84.1, and 90.8% %, respectively, in non-smoke inhalation group (one-tailed t test, p < 0.01, p < 0.01, and p < 0.05 at 4, 6, and 8 weeks, respectively). Our histologic observations revealed that the granulation tissue resorption, bone formation, and remodeling were delayed in smoke inhalation group. The results of this study suggest that intermittent inhalation of cigarette smoke delays, but does not prevent, the bone healing in tibial lengthening.

Animals↗
PubMed1997

Management of large infected tibial defects with antibiotic beads local therapy and staged fibular osteoseptocutaneous free transfer.

Fifteen patients with tibial fractures complicated by large infected tibial defects were treated with a two-stage protocol. In the first stage, antibiotic-impregnated polymethylmethacrylate bead chains were used to obliterate the debrided osseous defect, and a meshed porcine skin was used for temporary wound coverage. In the second stage, the bead chains were removed, and the defects were reconstructed with a microvascularized fibular osteoseptocutaneous free transfer. The time between the first and second stages of treatment was 2 to 6 weeks. The bone defects ranged from 6 to 16 cm, and the skin defect areas ranged from 10 to 82 cm2. Wound healing and bony union were achieved in all 15 cases. An additional muscle flap or skin graft was required for only three patients with a large skin defect. Minor pin tract infections were seen in two patients. Stress fractures in three cases were successfully managed with bracing, external skeletal fixation or plating, and cancellous bone grafting. All of the most recent roentgenograms showed good consolidation and hypertrophy of grafted fibular bones. No recurrence of osteomyelitis was observed during an average follow-up period of 50 months (range, 36-86 months). We therefore conclude that this treatment protocol provides rapid recovery from osteomyelitis. The fibular osteoseptocutaneous graft is a useful method for the reconstruction of a large tibial defect, and it also offers the unique advantage of simultaneously reconstructing a moderate skin defect.

Adult↗
PubMed1997

Augmentative plate fixation for the management of femoral nonunion after intramedullary nailing.

Seventeen femoral nonunions after intramedullary nail internal fixation were treated with augmentative plate internal fixation. Six of them were initially managed with a Küntscher nail internal fixation; the other 11 fractures were managed with a locked nail internal fixation. All the femoral nonunions were caused by insecure fixation of the intramedullary nailing, in which a rotational instability of the fracture site was verified in all cases during operation. Leaving the intramedullary nail in situ, an augmentative plate fixation was applied to the fracture site to counter the rotational instability. A simultaneous bone grafting was performed in seven of them to repair the bony defect. All these patients walked bearing full weight on the extremity without aching at the fracture site within 3 months and all these 17 fractures obtained a bony union within an average of 7 months after this treatment. From our experience, we have found this method is a useful treatment for the nonunion of the femoral shaft fracture after an intramedullary nail internal fixation. The technique is simple and does not require any special instrument. It facilitates an early weight bearing and gives a quick recovery from nonunion.

Adolescent↗
PubMed1997

Staged management of infected humeral nonunion.

Fourteen patients with infected humeral nonunion complicated by sinus discharge were treated with a staged protocol consisting of (1) radical debridement with local antibiotic beads implantation, and (2) external skeletal fixation with autologous bone grafting. In the first stage, a thorough debridement and sequestrectomy were done. Antibiotic beads were used to obliterate the bone defect, and the wound was then directly closed. In the second stage, the bead chains were replaced with autogenous cancellous bone graft. Unilateral Hoffman external skeletal fixators were applied simultaneously. The mean follow-up period was 73.6 months (range, 29 months to 9 years). The length of time to achieve bony union ranged from 3.5 to 8 months (average, 4.3 months). Hoffman pin complication was found in two cases, which were then shifted to plate internal fixation. All the infections were eradicated, and the wounds healed without further skin graft or flap coverage. All the fractures achieved bony union except for one in a patient who died. Most patients acquired satisfactory function of elbow motion after removal of external fixation and physical therapy. The method of two-stage management was effective for infected humeral nonunion. Not only was the infection eradicated and osseous union achieved, but also the limb function and joint motion were preserved.

Adult↗
PubMed1997

Different viral aetiology of hepatocellular carcinoma between two hepatitis B and C endemic townships in Taiwan.

In Taiwan, we found two hepatitis B virus (HBV)- and hepatitis C virus (HCV)-endemic townships, Paisha and Tzukuan, with an anti-HCV prevalence of 19 and 37% in men, and 26 and 38% in women, respectively. The hepatitis B surface antigen (HBsAg)-positive rates were 25 and 18%, for men and women in Paisha, and 25 and 22% in Tzukuan, respectively. According to the national death certification database (1982 to 1991), the annual age-adjusted mortality rates per 100,000 population for liver cancer among men and women were 83.0 and 13.8, respectively, in Paisha, and 55.9 and 17.0 in Tzukuan compared with 30.9 and 9.1 in Taiwan as a whole. The male-to-female ratios were 6.0 in Paisha and 3.3 in Tzukuan. Aetiology of 11 cases of hepatocellular carcinoma (HCC) from Paisha and 14 cases from Tzukuan were analysed. All HCC cases from Paisha were HBsAg positive, while 13/14 HCC cases from Tzukuan were anti-HCV positive. The endemic duration of HCV in Tzukuan seemed long enough to induce HCC, but the HCV appeared to be a newly introduced infection in Paisha.

Adult↗
PubMed1997

Measurement of polyethylene wear in cementless total hip arthroplasty.

We made a clinical study of polyethylene wear in 240 hips of 187 patients having primary total hip arthroplasties from 1989 to 1990, using uncemented Osteonics components, with a head size of 26 mm. We excluded cups with anteversion of over 20 degrees and measured linear wear by a new method using a digitiser and special software of our design. Follow-up was from two to five years (mean 4.3). The mean age at operation was 50.3 years, with more men than women (1.4:1). The mean linear wear per year was 0.15 mm; this did not increase with the longevity of the prosthesis (p = 0.54). In 59 hips showing evidence of osteolysis, the mean linear wear rate was significantly higher at 0.23 mm/year (p <0.001). The mean linear wear rate also correlated significantly with age at the time of operation (p = 0.008), but we found no significant correlations with body-weight, gender, aetiology of the disease, thickness of polyethylene, or cup position. Our new method of measurement is time-saving and reproducible. The results confirm the greater rate of linear wear of polyethylene in patients showing osteolysis and in those who are younger.

Adult↗
PubMed1997

Pyomyositis of the calf muscles mimicking distal deep venous thrombosis: a case report.

Pyomyositis is a pyogenic infection of skeletal muscle. It is relatively rare in temperate climates. Unfamiliarity with the lesion may lead to a delay in diagnosis. This report describes pyomyositis of the calf muscles in a patient with chronic hepatitis whose clinical symptoms simulated those of distal deep venous thrombosis. The correct diagnosis was not made until computed tomography revealed a local abscess in the calf muscles.

Abscess↗
PubMed1997

Primary uncemented Osteonics total hip arthroplasty: preliminary results of 2-6 year follow-up.

BACKGROUND: Cemented total hip arthroplasty (THA) bears the inherent disadvantages of cement complications. A research toward the improvement of uncemented prosthesis design continues to evolve. The purpose of this report is to present the preliminary results and to identify common problems in uncemented THA. METHODS: The results of 402 primary Osteonics total hip prostheses were reviewed with an average follow-up period of 3.1 years. The postoperative rating according to the modified D' Aubigne & Postel hip score included functional and radiographic analysis. RESULTS: The results were rated as good or excellent in 95% of hips. Stable fixation of the prosthesis was shown in 97% of radiographs. The most common zone of focal osteolysis was in the periarticular area. CONCLUSION: The clinical results in a 2 to 6 year follow-up was encouraging. A relatively high incidence of thigh pain did not correlate with femoral canal filling of prosthesis. Periarticular osteolysis is still an unsettled problem in uncemented prostheses and needs further investigation.

Adolescent↗
PubMed1997

Slipped capital femoral epiphyses in a patient with primary hyperparathyroidism.

Slipped capital femoral epiphyses are rarely associated with primary hyperparathyroidism, and only four cases have been documented in the English literature. We report such a case. A 13-year-old boy presented with bilateral slipped capital femoral epiphyses. Investigation showed that he had primary hyperparathyroidism due to a parathyroid adenoma. The adenoma was removed, and then the epiphyses were pinned in situ 3 weeks later. The pins were removed 3 months postoperatively when the physes had closed. The patient had a painless hip 1 year later at follow-up. We concluded that identification and excision of the hyperparathyroid adenoma and in situ pinning of the slipped epiphyses results in satisfactory treatment of the condition.

Adenoma↗
PubMed1997

Incidence of hepatitis C infection in a hepatitis C endemic township in southern Taiwan.

To realize the incidence of hepatitis C virus (HCV) infection in an HCV endemic township, Tzukuan, in Taiwan, we conducted a follow-up community-based survey. A total of 173 adults, 82 males and 91 females, with mean age of 55.5 +/- 9.9 years received initial and follow-up anti-HCV tests with one-year interval. One (1.2%, 95% CI: 0%-5.5%) of 84 anti-HCV-positive subjects was negative-seroconversion, and 4 (4.5%, 95% CI: 0.2%-8.8%) of 89 anti-HCV-negative subjects were positive-seroconversion. The results indicated that hepatitis C might be still spreading in the HCV-endemic area now.

Adult↗
PubMed1997

Altered p16/MTS1/CDKN2 and cyclin D1/PRAD-1 gene expression is associated with the prognosis of squamous cell carcinoma of the esophagus.

The p16/MTS1/CDKN2 gene and the cyclin D1/PRAD-1 gene cooperatively regulate cyclin-dependent kinase 4-mediated phosphorylation of pRB in the cell cycle of normal cells. p16/CDKN2 gene and cyclin D1/PRAD-1 gene alterations have been detected in squamous cell carcinoma cell lines and in several primary squamous cell carcinomas of the esophagus. We immunohistochemically assessed p16 and cyclin D1 expression in 111 squamous cell carcinomas of the esophagus after evaluation of the antibodies against p16 and cyclin D1 protein using four squamous cell carcinoma cell lines. Loss of p16 expression was detected in 56 of 111 cases (50%). The mean number of metastatic lymph nodes without p16 expression was significantly higher than the number of nodes with p16 expression (P = 0.04). The postoperative survival rate for patients without p16 expression was significantly lower than that of patients with p16 expression (P = 0.04). Cyclin D1 overexpression was found in 28 of the 111 cases (25%) and correlated with distant organ metastasis after curative surgery (P = 0.05). The survival rate of patients with cyclin D1 overexpression was significantly lower than that of patients without cyclin D1 overexpression (P = 0.01). A positive correlation between the loss of p16 expression and cyclin D1 overexpression was observed (P = 0. 03). The loss of p16 expression and overexpression of cyclin D1 may be useful prognostic indicators in patients with squamous cell carcinomas of the esophagus. It may be possible to select more suitable treatment for patients with squamous cell carcinomas of the esophagus by evaluating the status of p16 and cyclin D1 expression.

Adult↗
PubMed1996

Calorimetric characterization of the formation of acrylic type bone cements.

The formation of acrylic bone cements upon heating was investigated by differential scanning calorimetry (DSC). The effects of the contents of initiators, accelerator, biocompatibilizer, and crosslinking agents on the rate and the heat of polymerization during DSC heating were studied. The rate and the heat of polymerization (delta H) were characterized by the peak temperature and the area of the DSC exotherm, respectively. It was found that both the rate and heat of polymerization decreased with increasing heating rate. The delta H was increased considerably with increasing benzoyl peroxide (BPO) initiator concentration from 1 to 10% (w/v), whereas the rate of polymerization was reduced significantly. An increase in azobisisobutyronitrile (AIBN) initiator concentration also induced an increase in delta H, but the rate of reaction was not affected considerably. The addition of accelerator promoted the rate of reaction but resulted in a drop in delta H. The rate of polymerization for the system containing BPO initiator was increased quite significantly with the addition of hydroxyethyl methacrylate (HEMA) biocompatibilizer, while the delta H was slightly increased. For the system using AIBN as the initiator, the rate of polymerization was decreased slightly and the delta H dropped significantly with the addition of HEMA. The effect of ethylene glycol dimethacrylate (EGDMA) crosslinking agent was also examined. Polymerization became more rapid with the addition of EGDMA in the bone cement using BPO initiator, while it remained approximately constant for the system using AIBN as the initiator. No systematic change in delta H was observed with the addition of EGDMA in both systems. This study demonstrated that DSC is a potential tool to measure the amount of heat released and also the rate of polymerization for bone cements.

Acrylates↗
PubMed1996

Vastus lateralis flaps for chronic recalcitrant hip infection.

Between January 1991 and May 1994, 11 patients with chronic recalcitrant infection of the hip joint were successfully treated by transposition of a vastus lateralis flap. The average duration of the infection was 7.9 months. The patients had undergone an average of 2.8 procedures in an attempt to eradicate the infection before transposition of the flap. Three patients had recurrence of drainage after the procedure and were successfully treated with antibiotics and local debridement. Delayed exchange total hip arthroplasty was performed in 2 patients. All the patients achieved wound healing and infection resolution. This flap has several advantages. The donor site has not usually been scarred from previous operations; the flap has a consistent vascular pedicle which permits a wide arc of rotation; knee extension is unaffected; the transposed portion of the vastus lateralis can act as a cushion between the acetabulum and the proximal femur; it may also act as a tether to prevent extreme proximal migration of the femur. In the management of chronic recalcitrant infection of the hip, use of a transposition flap can be combined with a Girdlestone arthroplasty. It can also be an interim procedure before a further total joint arthroplasty.

Adult↗
PubMed1996

Adaptive Morse-coded single-switch communication system for the disabled.

Automatic recognition of Morse-code is generally developed at a fixed typing rate. However, this is not suitable for the disabled due to their difficulty in maintaining a stable typing rate. In this paper, a system recognizing varying typing speeds is developed using an adaptive technique, the Least-Mean Square (LMS) algorithm. This system helps the disabled have a wide latitude and varying typing speeds in single-switch communication with the Morse-code.

Abbreviations as Topic↗
PubMed1996

Distal tibial nonunion treated by intramedullary reaming with external immobilization.

Seventeen distal tibial nonunions were treated by a combination of metal removal with closed intramedullary reaming for internal bone graft and application of a long leg cast for aseptic nonunions and an external fixator for quiescent septic nonunions. The nonunions were present for a median of 1.8 years (range, 1.2-3.4 years). All achieved a solid union with a union period of 5.2 +/- 1.6 months. There was one complication of a renewed infection in a septic nonunion. The functional rating score improved from all unsatisfactory before treatment to 13 satisfactory after treatment. The other four (all were infected nonunions) also improved from poor to a fair outcome. In conclusion, the technique described is a simple and effective method to treat some complex distal tibial nonunions.

Adult↗
PubMed1996

Management of large infected tibial defects with radical debridement and staged double-rib composite free transfer.

Seven patients with tibial fractures complicated by large infected tibial defects were treated with a two-stage protocol. In the first stage, antibiotic-impregnated polymethylmethacrylate (PMMA) bead chains were used to obliterate the debrided osseous defect, and a meshed porcine skin was used for temporary wound coverage. In the second stage, the bead chains were removed, and the defects were reconstructed with a microvascularized double-rib and serratus anterior muscle composite free transfer. The interval between the first and second operations was 2 to 4 weeks. The bone defects ranged from 6 to 9 cm, and the skin defect areas ranged from 20 to 40 cm2. Wound healing and bony union was achieved in all seven cases. Minor pin track infection was seen in one patient. Stress fractures in two cases were successfully managed with patellar tendon short-leg bracing for 6 months in one case and a plate internal fixation in the other case. Within 2 years, all seven patients returned to light work without any external support, and all of their most recent radiographs showed good consolidation and hypertrophy of grafted rib bones. No occurrence of osteomyelitis was observed during an average follow-up of 37 months (out of a range of 24 to 50 months). We conclude that this treatment protocol provides rapid recovery from osteomyelitis and the double-rib graft is a useful, durable alternative for large tibial defect management.

Adult↗
PubMed1996

Biomechanical analysis of location of lag screw of a dynamic hip screw in treatment of unstable intertrochanteric fracture.

OBJECTIVE: The aim of this study was to assess the most adequate location of a lag screw of a dynamic hip screw in the treatment of an unstable intertrochanteric fracture. METHODS: Six pairs of proximal femora obtained from fresh adult cadavers were inflicted with iatrogenic unstable intertrochanteric fractures. Fractures of both sides were stabilized with two different favored locations of a lag screw and tested by a Material Testing System machine with increased loads to evaluate the relative migration of the femoral head. RESULTS: There was significant difference (p < 0.05) with less migration of the femoral head by inferior insertion of a lag screw in the frontal plane and central insertion in the coronal plane. CONCLUSIONS: Based on theoretical and experimental considerations, the most adequate location of a lag screw of a dynamic hip screw should be inferior in the frontal plane and central in the coronal plane.

Adult↗