Biomedical subjects

C L Tai

Publications and source records attributed to C L Tai.

At least 19 recordsLinked to original sources

PubMed2001

Patellar tension band wiring: a revised technique.

Using a modified AO tension band wiring technique to treat a patellar fracture has become popular and has achieved a high success rate. However, the technique of Kirschner wire insertion has not been considered in detail, which may migrate and consequently introduce fragments loss of reduction. A revised technique involving bending both ends of the Kirschner wires was prospectively studied. Sixty-eight consecutive patients were so treated, and 62 patients were followed-up for at least 2 years (range 2-6 years). All fractures healed with a union rate of 100% (62/62) and a union period of 2.5 +/- 0.5 months. Skin irritation was noted in 2 patients (3%). All patients achieved a satisfactory result. We therefore recommend this revised technique to treat all patellar fractures because of its high union rate and low complication rate.

Adolescent↗

PubMed2001

Structure-based mutational analysis of the hepatitis C virus NS3 helicase.

The carboxyl terminus of the hepatitis C virus (HCV) nonstructural protein 3 (NS3) possesses ATP-dependent RNA helicase activity. Based on the conserved sequence motifs and the crystal structures of the helicase domain, 17 mutants of the HCV NS3 helicase were generated. The ATP hydrolysis, RNA binding, and RNA unwinding activities of the mutant proteins were examined in vitro to determine the functional role of the mutated residues. The data revealed that Lys-210 in the Walker A motif and Asp-290, Glu-291, and His-293 in the Walker B motif were crucial to ATPase activity and that Thr-322 and Thr-324 in motif III and Arg-461 in motif VI significantly influenced ATPase activity. When the pairing between His-293 and Gln-460, referred to as gatekeepers, was replaced with the Asp-293/His-460 pair, which makes the NS3 helicase more like the DEAD helicase subgroup, ATPase activity was not restored. It thus indicated that the whole microenvironment surrounding the gatekeepers, rather than the residues per se, was important to the enzymatic activities. Arg-461 and Trp-501 are important residues for RNA binding, while Val-432 may only play a coadjutant role. The data demonstrated that RNA helicase activity was possibly abolished by the loss of ATPase activity or by reduced RNA binding activity. Nevertheless, a low threshold level of ATPase activity was found sufficient for helicase activity. Results in this study provide a valuable reference for efforts under way to develop anti-HCV therapeutic drugs targeting NS3.

Adenosine Triphosphatases↗

PubMed2001

Tension-band technique for ankle fusion.

A prospective study was conducted to develop a better technique for ankle fusion. Eleven consecutive patients were treated using the tension-band technique for ankle fusion and underwent follow-up for a minimum of 2 years (range: 2-5 years). All 11 patients achieved solid fusion for a fusion rate of 100%. Average time to fusion was 3 months (range: 2-6 months). The indication for ankle fusion was intractable aching pain that could not be controlled by conservative methods. Two of 11 patients underwent surgery due to infected arthritis. After ankle fusion, there was no recurrence of infection during a 3-year follow-up period. The technique included osteotomy of the bimalleoli from the inside out, removal of articular cartilage and preserving wedge space for cancellous bone grafting, with or without staple stabilization, and external immobilization supplementation. The functional outcome in all 11 patients improved from unsatisfactory preoperatively to satisfactory at latest follow-up (P<.001). No significant complications were noted. This simple technique proved excellent for ankle fusion with a satisfactory outcome and is recommended for treating severe ankle arthropathies.

Adult↗

PubMed2000

Complications of liner locking system in Micro-structured Omnifit acetabular components: a radiographic evaluation of 887 hips followed for 5-10 years.

We evaluated 887 hips in 672 patients with uncemented MicroStructured Omnifit acetabular components for liner locking complications. We found 2 types of radiographic signs of liner locking system complications in 7 hips, developing between 2 and 4 years postoperatively. The incidence of liner locking system complications was 0.8% using this modular acetabular component. We recommend that a patient who has received a total hip arthroplasty including a MicroStructured Omnifit acetabular component should be monitored frequently for radiographic signs of liner locking system complications, especially with a polyethylene thickness of less than 8 mm.

Adult↗

PubMed2000

Biomechanical comparison for different configurations of tension band wiring techniques in treating an olecranon fracture.

BACKGROUND: The aim of this study was to compare the superiority between the newly designed modified AO tension band wiring technique and the traditional modified AO tension band wiring technique in treating an olecranon fracture. METHODS: Eight pairs of fresh cadaveric ulnae were tested biomechanically. After transverse osteotomy of the olecranon, all left ulnae were fixed by the traditional modified AO technique with two Kirschner wires inserted through the anterior ulnar cortex and all right ulnae by the new technique with two Kirschner wires inserted into the marrow cavity from the olecranon to the ulnar styloid process. All specimens were tested by the Material Testing System machine to evaluate fragment displacement and the maximal failure load. A dual linear variable displacement transducer was used to measure relative minimal displacement. RESULTS: There was no significant difference between the techniques. The maximal failure load by either technique was more than 80 kg. Even at testing failure, no Kirschner wires migrated proximally. CONCLUSION: The new technique may be applied widely to treat all olecranon fractures, because it is a technically easier and safer technique. Less than 5.5-kg loads could be permitted in daily activity postoperatively. A single tolerable loading weight should not exceed 8 kg. Kirschner wires will not migrate proximally, despite increased joint loading. Clinically, this study may confirm indirectly the hypothesis that proximal migration of Kirschner wires was mainly due to triceps traction.

Adolescent↗

PubMed2000

MicroStructured Omnifit acetabular components: concerns with locking system complications and excessive polyethylene wear.

BACKGROUND: We began to use cementless MicroStructured Omnifit acetabular components in November 1988. Liner dislodging and excessive polyethylene wear later occurred in some of our patients. This finding prompted us to review our experience with the use of such modular acetabular components. METHODS: A total of 887 hips in 672 patients, which had been fitted with cementless MicroStructured Omnifit acetabular components, were evaluated for locking system complications using radiographic examinations. Of the cases, 240 hips which had received a 26-mm femoral head (group 1) and 110 hips which had received a 32-mm femoral head (group 2) were compared using a digitiser to determine the influence of femoral head size on polyethylene wear. RESULTS: There were two types of radiographic signs of locking system complications in 7 hips, at a mean time of 2.9 years after implantation. The incidence of liner locking system complications using this modular acetabular component was 0.8%. The mean liner wear rate per year was 0.15 mm in group 1 and 0.20 mm in group 2 (p <0.005). The initial polyethylene thickness ranged from 5.9 to 13.6 mm in group 1, compared with 3.9 to 10.6 mm in group 2 (p < 0.005). CONCLUSION: A patient who has received a total hip arthroplasty that includes a MicroStructured Omnifit acetabular component should be monitored frequently for radiographic signs of locking system complications. In this study, the mean liner wear rate was significantly higher in group 2. Inadequate polyethylene thickness in this group was implicated as the major cause of excessive polyethylene wear.

Adolescent↗

PubMed1999

Effect of reaming bone grafting on treating femoral shaft aseptic nonunion after plating.

Rigid intramdullary nailing with cancellous bone grafting provided by intramedullary reaming was prospectively used to treat femoral shaft aseptic nonunions after plating. Indications for this technique were a femoral shaft nonunion with an inserted plate, no previous infection sign in the treatment course, less than 1.5 cm shortening, and no segmental bony defects. After the plate was removed, a flexible guidewire was inserted antegradely. The local wound was closed, and intramedullary reaming was done as widely as possible until some resistance to it occurred. Finally, a rigid intramedullary nail was inserted. Twenty-four consecutive patients were treated with this regimen, and 21 were followed-up for at least 1 year (range 1-5 years). All 21 nonunions healed with a union rate of 100% (21/21). The time to union was 4.5 +/- 1.0 months. There were no significant complications. We conclude that for indicated cases, reaming bone grafting is a very effective technique and avoided donor site morbidity. Therefore, whenever possible, this technique could be considered first.

Adult↗

PubMed1999

Early polyethylene wear and osteolysis in cementless total hip arthroplasty: the influence of femoral head size and polyethylene thickness.

We examined initial polyethylene thickness, early polyethylene liner wear, and osteolysis in 350 primary, cementless total hip arthroplasties (THAs). All of the prostheses were of identical design and used Omnifit components. In the 32-mm head group, the mean liner wear correlated significantly with polyethylene thickness (P<.001) and increased rapidly with initial thinner polyethylene following a logarithmic model, although this increase was not statistically significant (r = -.633). Inadequate polyethylene thickness in the 32-mm head group was implicated as the major cause of higher liner wear. A minimal polyethylene thickness of 7 mm is recommended in cementless metal-backed THAs. The use of a large head combined with poor prosthetic design appeared to be responsible for the unacceptably high incidence of femoral osteolysis.

Acetabulum↗

PubMed1999

High success rate with exchange nailing to treat a tibial shaft aseptic nonunion.

OBJECTIVE: To investigate the effects of tibial exchange nailing in treating a tibial shaft aseptic nonunion and to establish optimal indications for using this technique. DESIGN: Prospective, consecutive. SETTING: University hospital. METHODS: Twenty-five consecutive tibial shaft aseptic nonunions were prospectively treated with the exchange nailing technique. Indications for this procedure were a tibial shaft aseptic nonunion that had previously been treated with an inserted nonreamed or reamed intramedullary nail, displayed less than one centimeter of shortening, was with or without rotational or angular deformity, exhibited no segmental bony defects, and was anatomically suited for conventional or locked reamed intramedullary nail stabilization. The marrow cavity was reamed as extensively as possible, and a rigid intramedullary nail with stable fixation was inserted. RESULTS: During a follow-up period of two to four years (median thirty-two months), twenty-four nonunions healed, on average, in four months (range three to six months). The one remaining nonunion healed four months after a cancellous bone grafting procedure. No wound infection or malunion was noted. CONCLUSION: Because of its high union rate, low complication rate, and simplicity of method, we believe that the exchange nailing technique should be considered preferentially for all indicated cases.

Adolescent↗

PubMed1999

Bone healing of tibial lengthening is delayed by cigarette smoking: study of bone mineral density and torsional strength on rabbits.

OBJECTIVE: We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. METHODS: Twelve male rabbits were divided into two groups of six animals each. The first group underwent intermittent cigarette smoke inhalation, and the second group did not undergo intermittent cigarette smoke inhalation. Each animal's right tibia was lengthened 5 mm by using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals 1 day before operation and 3, 4, 5, and 6 weeks after operation. All of the animals were killed 6 weeks postoperatively for biomechanical testing. RESULTS: By using the preoperative BMD as an internal control, we found that the BMD of the smoke-inhalation group was decreased significantly compared with the non-smoke-inhalation group. The mean %BMD at 3, 4, 5, and 6 weeks were 49.9%, 61.2%, 65.9%, and 71.0%, respectively, in the smoke-inhalation group, whereas the mean %BMD were 54.9%, 71.8%, 76.4%, and 82.0%, respectively, in the non-smoke-inhalation group (two-tailed t test, p > 0.05, p < 0.01, p < 0.01 and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). By using the contralateral nonoperated tibia as internal control, we found that torsional strength of the smoke-inhalation group was decreased significantly compared with the non-smoke-inhalation group. The mean percentage of maximal torque was 63.8% in the smoke-inhalation group, whereas the mean percentage of maximal torque was 77.1% in the non-smoke-inhalation group (two tailed t test, p < 0.01). CONCLUSION: This study suggests that cigarette smoking delays the mineralization during the bone healing process of distraction osteogenesis and, thus, decreases the mechanical strength of the regenerating bone.

Absorptiometry, Photon↗

PubMed1999

Treatment of femoral neck nonunions with a sliding compression screw: comparison with and without subtrochanteric valgus osteotomy.

BACKGROUND: The aim of this prospective study was to investigate and compare the results of treatment of femoral neck nonunions using a sliding compression screw (SCS) with and without subtrochanteric valgus osteotomy (SVO). METHODS: Thirty-two consecutive patients with femoral neck nonunions, which sustained no osteonecrosis of the femoral head based on bone scan study, were prospectively treated with SCS with (21 patients) or without (11 patients) SVO. The indication for SCS with SVO was a femoral neck nonunion with leg shortening of more than 1.5 cm. SCS without SVO was for leg shortening of less than 1.5 cm. RESULTS: Seventeen patients with osteotomy and nine patients without osteotomy were followed for at least 2 years (range, 2-8 years). All femoral neck fractures healed, with a union period of 4.6+/-1.0 months (95% confidence interval, 4.1-5.1 months) for osteotomy cases and 4.6+/-1.1 months (95% confidence interval, 3.8-5.4 months) for nonosteotomy cases (p = 0.83). However, in the osteotomy group, two patients sustained osteonecrosis of the femoral head, and nonunion remained in 1 patient at the osteotomy site (complication rate, 18%; 3 of 17 patients). There were no complications in the nonosteotomy group (p = 0.26). The average lengthening achieved from osteotomy was 1.0 to 1.5 cm (p < 0.001). CONCLUSION: Using SCS without SVO to treat femoral neck nonunions can result in a very satisfactory outcome. It is thus preferred for indicated patients. SCS without SVO, however, cannot concomitantly correct a femoral neck shortening; furthermore, shortening may deteriorate because of a telescoping effect. For patients with evident shortening, therefore, combined SVO with SCS is more suitable.

Adolescent↗

PubMed1999

Hyperbaric oxygen therapy mitigates the adverse effect of cigarette smoking on the bone healing of tibial lengthening: an experimental study on rabbits.

OBJECT: We investigated whether -intermittent hyperbaric oxygen (HBO) therapy can mitigate the adverse effects of cigarette smoking on the bone healing of tibial lengthening by using a previously validated rabbit model. METHODS: Eighteen male rabbits were randomly divided into three groups of six animals each. Group 1 (smoking plus HBO) went through intermittent cigarette smoke inhalation and hyperbaric oxygen therapy, group 2 (control) did not go through intermittent cigarette smoke inhalation or hyperbaric oxygen therapy and group 3 (smoking) went through intermittent cigarette smoke inhalation. Each animal's right tibia was lengthened 5 mm by using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all the animals at 1 day before operation and 3, 4, 5, and 6 weeks after operation. All of the animals were killed at 6 weeks postoperatively for biomechanical testing. RESULTS: By using the preoperative BMD as an internal control, we found that the BMD of group 1 (smoking plus HBO)and group 2 (control) was superior to that of group 3 (smoking). The mean %BMD at 3, 4, 5, and 6 weeks were 58.6%, 66.6%, 73.7%, and 83.8%, respectively, in group 1, whereas the mean %BMD were 52.0%, 64.3%, 70.1%, and 76.2%, respectively, in group 2, and the mean %BMD were 46.2%, 54.0%, 64.9%, and 69.4%, respectively, in group 3 (two-tailed t test, p > 0.05, p > 0.05, p > 0.05, and p < 0.05 at 3, 4, 5, and 6 week respectively between group 1 and group 2, p < 0.01,p < 0.01,p < 0.01, and p < 0.01 at 3, 4, 5, and 6 week, respectively, between group 1 and group 3 and p < 0.05, p < 0.05, p < 0.05, and p < 0.05 at 3, 4, 5, and 6 week respectively between group 2 and group 3). By using the contralateral nonoperated tibia as an internal control, we found that the torsional strength of group 1 (smoking plus HBO) and group 2 (control) was superior to that of group 3 (smoking). The mean percentage of maximum torque was 80.9% in group 1 (smoking plus HBO) and was 78.0% in group 2 (control), whereas the mean percentage of maximum torque was 59.6 % in group 3 (smoking) (two-tailed t test, p < 0.05 between groups land 3 and between groups 2 and 3, whereas p > 0.05 between groups 1 and 2). CONCLUSION: This study suggests that smoke inhalation delays the bone healing in tibial lengthening; however, HBO mitigates the delayed healing effect of smoke inhalation and, thus, helps the smoking animal in achieving an expeditious bone healing in tibial lengthening.

Absorptiometry, Photon↗

PubMed1998

Treatment of cutout of a lag screw of a dynamic hip screw in an intertrochanteric fracture.

Sixteen consecutive patients with cutout of a lag screw of a dynamic hip screw fixation in an intertrochanteric fracture were treated with reinsertion of a lag screw, bone cement supplementation in the neck-trochanter, and subtrochanteric valgus osteotomy. Postoperatively, patients were permitted to ambulate with protected weight-bearing. Fourteen patients were followed-up for at least 1 year (median 2 years; range 1-3 years), and all had a solid union. The union period took a median of 5 months, with a range of 3-7 months. Usually, union of an intertrochanteric fracture was faster than that of subtrochanteric osteotomy (P < 0.01). There were no complications of wound infection, loss of reduction, cutout of a lag screw, or osteonecrosis of the femoral head. From clinical and theoretical considerations, we conclude that despite cutout of a lag screw of a dynamic hip screw fixation being difficult to treat, out technique still can provide an excellent outcome. Therefore, we strongly recommend its wide use.

Aged↗

PubMed1998

Staple augmentation to treat a humeral nonunion after failed Seidel locked nailing.

Seidel locked nailing has been successfully used to treat a humeral shaft fracture or nonunion. However, if union fails despite this treatment, the next approach to try has not been well defined. We, therefore, developed a technique using a staple to enforce the local stability without removing the failed nail. The technique was very simple, and the outcome was always satisfactory.

Adult↗

PubMed1998

Bone healing of tibial lengthening is enhanced by hyperbaric oxygen therapy: a study of bone mineral density and torsional strength on rabbits.

We investigated the effect of intermittent hyperbaric oxygen (HBO) therapy on the bone healing of tibial lengthening in rabbits. Twelve male rabbits were divided into two groups of six animals each. The first group went through 2.5 atmospheres absolute of hyperbaric oxygenation for 2 hours daily, and the second group did not go through hyperbaric oxygenation. Each animal's right tibia was lengthened 5 mm using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals at 1 day before operation and at 3, 4, 5, and 6 weeks after operation. All of the animals were killed at 6 weeks postoperatively for biomechanical testing. Using the preoperative BMD as an internal control, we found that the BMD of the HBO group was increased significantly compared with the non HBO group. The mean %BMD at 3, 4, 5, and 6 weeks were 69.5%, 80.1%, 87.8%, and 96.9%, respectively, in HBO group, whereas the mean %BMD were 51.6%, 67.7%, 70.5%, and 79.2%, respectively, in non-HBO group (two tailed t test, p < 0.01, p < 0.01, p < 0.01, and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of lengthened tibia of the HBO group was increased significantly compared with the non-HBO group. The mean percent of maximal torque was 88.6% in HBO group at 6 weeks, whereas the mean percent of maximal torque was 76.0% in non-HBO group (two-tailed t test, p < 0.01). The results of this study suggest that the bone healing of tibial lengthening is enhanced by intermittent hyperbaric oxygen therapy.

Absorptiometry, Photon↗

PubMed1998

Treatment of clavicular aseptic nonunion: comparison of plating and intramedullary nailing techniques.

OBJECTIVE: The aim of this retrospective study was to investigate and compare the effects of plating and intramedullary nailing in the treatment of clavicular aseptic nonunion. METHODS: Thirty-three consecutive patients with middle-third clavicular aseptic nonunions with previous nonoperative treatment were treated by plating (13 patients) and intramedullary nailing (20 patients) with supplementary cancellous bone grafting. The indications for such treatment were middle-third aseptic nonunions without previous operative treatment and with local pain or tenderness, deformity, or neurologic complaint. The choice of plating or intramedullary nailing was according to the surgeon's individual preference. RESULTS: Twenty-nine patients were followed for at least 1 year (range, 1-7 years; median, 3 years; plating, 11; intramedullary nailing, 18). The union rate was 81.8% (9 of 11) for plating and 88.9% (16 of 18) for intramedullary nailing (p = 0.35, Fisher's exact test). The union period was 4.0 +/- 1.3 months for plating and 4.1 +/- 1.1 months for intramedullary nailing (p = 0.80, unpaired Student's t test). The complication rate was 27.3% (3 of 11) for plating and 11.1% (2 of 18) for intramedullary nailing (p = 0.21, Fisher's exact test). There were no significant differences in other parameters. CONCLUSION: Intramedullary nailing may have a higher union rate with a lower complication rate than plating (p > 0.05). At least in common situations, it is not inferior to plating. Whenever possible, therefore, intramedullary nailing should be used preferentially to treat clavicular aseptic nonunion without previous operative treatment. Nevertheless, both techniques have relatively higher nonunion rates in the treatment of clavicular nonunion than in the treatment of other long-bone nonunions. Gentle handling of surrounding soft tissues to reduce bony fragments should be strictly executed.

Adult↗

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

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↗