Additively manufactured biomedical Ti-Nb-Ta-Zr lattices with tunable Young's modulus: Mechanical property, biocompatibility, and proteomics analysis

Some β-Ti alloys, such as Ti-Nb-Ta-Zr (TNTZ) alloys, exhibit a low Young's modulus and excellent biocompatibility. These alloys are promising new generation biomedical implant materials. Selective laser melting (SLM) can further enable customer-specific manufacturing of β-Ti alloys to satisfy the ever-increasing need for enhanced biomedical products. In this study, we quantitatively determined the relationships between porosity, yield strength, and Young's modulus of SLM-prepared TNTZ lattices. The study constitutes a critical step toward understanding the behavior of the lattice and eventually enables tuning the Young's modulus to match that of human bones. Fatigue properties were also investigated on as-printed lattices in terms of the stress limit. The biocompatibility study included a routine evaluation of the relative cell growth rate and a proteomics analysis using a common mouse fibroblast cell line, L929. The results indicated that the as-printed TNTZ samples exhibited evidence of protein proliferation of the L929 cells, particularly P06733, and that those proteins are responsible for biological processes and molecular functions. They in turn may have promoted cell regeneration, cell motility, and protein binding, which at least partially explains the good biocompatibility of the as-printed TNTZ at the protein level. The study highlights the promising applications of additively manufactured TNTZ as a bone-replacing material from mechanical and biocompatibility perspectives.

Ultrasound examination of patellar tendon after harvest for anterior cruciate ligament reconstruction

BACKGROUND AND PURPOSE

Reconstruction of ruptured anterior cruciate ligament (ACL) using the middle-third of the patellar tendon has become an established procedure. However, current studies of donor site morbidity have reported discrepant results. This study used ultrasound imaging to evaluate morphologic changes in the patellar tendon after harvest for ACL reconstruction.

METHODS

Twenty-nine patients who had undergone successful ACL reconstruction with patellar tendon graft more than 1 year previously were enrolled in the study. Ultrasound imaging was used to compare the width, thickness, and tissue reaction of patellar tendons between the operated and contralateral sides.

RESULTS

The operated side was 4.8% wider on average than the contralateral side (p < 0.05). The operated side was also 58.3% thicker on average (p < 0.0001), with irregular margins and heterogenous echogenecity.

CONCLUSION

The donor site of the patellar tendon was significantly wider and thicker and was heterogenous when examined on sonogram more than 1 year postoperatively.

Anterior tibia spine fracture in children: follow-up evaluation by biomechanical studies

BACKGROUND

The treatment of anterior tibial spine (ATS) fracture in children is in controversy. Previous studies have shown that most of the children who sustained ATS fractures have objective evidence of the anterior cruciate ligament (ACL) laxity at follow-up, but detailed biomechanical analysis of the knee joint has seldom been performed.

METHODS

Eight ATS fractures in children at a mean age of 12 years were treated from 1989 to 1994. Two were of Meyer's classification type I, 3 were of type II, and 3 were of type III. The treatment varied from casting to open reduction & internal fixation (ORIF) by pulling through suture or biofix absorbable screw. Patients were followed with radiological, clinical and biomechanical analysis. KT 1000 knee arthrometer was used to evaluate the laxity of ACL. Cybex isokinetic machine was used to evaluate knee extensor and flexor strength.

RESULTS

During an average follow-up period of 47 months, all fractures showed to unite well on X-ray except 1 untreated type I fracture who had malunion. Only one had subjective complaint of instability, but 3 had clinical signs of instability. Objective evidence of laxity, determined by KT-1000 arthrometer, was noted in 4 patients. Decreased muscle strength, determined by Cybex isokinetic machine, was more prominent in hamstrings than in quadriceps.

CONCLUSIONS

Patients with milder ATS fracture (type I & II), if treated inappropriately, may still result in ACL laxity and knee muscle strength deficiency. Type III ATS fractures, if treated well by ORIF, tend to recover nearly normal ACL function and muscle strength.

Intrafamilial transmission of hepatitis C virus in hemodialysis patients

The prevalence of hepatitis C virus (HCV) infection in chronic hemodialysis patients ranges from 20 to 50% and these patients may serve as a reservoir of infection for their household contacts. The aim of this study was to investigate the prevalence of anti-HCV in hemodialysis patients and their families, and to evaluate possible routes of infection. One hundred eighty-six family members of 84 hemodialysis patients and 529 healthy adults were enrolled. The family members consisted of 50 spouses, 96 children, 11 parents, 29 siblings, and other relatives living together with the patients. Serum samples were collected for testing anti-HCV. Exposure to risk factors was obtained by a questionnaire and an interview. The results showed that prevalence of anti-HCV in hemodialysis patients was 44%, whereas in family members it was 5.4%, not significantly different from that of age-matched healthy adults (standardized morbidity rate = 1.51, P = 0.390). The anti-HCV rate in family members tended to increase with age, and a spouse of an infected hemodialysis patient had a higher risk of HCV infection than other family members (15% vs. 2.6%, odds ratio 6.6, P = 0.058). Except for the age factor, no difference was found between seropositive and seronegative family members with respect to risk factors such as blood transfusion, surgery, frequent injections, dental procedures, or acupuncture. It was concluded that, although the anti-HCV positivity of hemodialysis patients is high, the risk of HCV infection for their family members is not higher than that of the general population. Among family members, spouses of seropositive hemodialysis patients have the highest risk of HCV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous ambulatory peritoneal dialysis in the elderly: a seven-year experience

This is a retrospective comparison of the status among the elderly (> or = 60 years, 23 patients) and younger patients (< 60 years, 31 cases) who initiated continuous ambulatory peritoneal dialysis (CAPD) between January 1986 and December 1992 at the National Taiwan University Hospital. The distribution of underlying renal diseases differed in the two groups with diabetes (56%) as the most common disease in the elderly, in contrast to glomerulonephritis (60%) in the younger patients. Haemodialysis intolerance and patient preference were the main reasons leading to the use of CAPD in both groups. Social rehabilitation status was poorer in the elderly group. The difference in cumulative risk of the first peritonitis episode and the technique failure rate were not statistically significant. The major causes of mortality were of vascular origin in both groups. In conclusion, similarities in the technique failure rate and the cumulative risk of peritonitis imply that CAPD is an acceptable alternative long-term dialysis therapy for geriatric patients.

Measurement of Chinese lumbar pedicles: with special reference to transpedicular screw fixation

BACKGROUND

Thorough understanding of the morphometric parameters of the lumbar pedicles is essential for transpedicular screw fixation. The purpose of this study is to establish a database for proper spinal instrumentations in Chinese patients.

METHODS

A total of 764 pedicles (L2-S1) were measured from spinal computed tomography (CT) of 100 Chinese volunteers. Parameters related to transpedicular fixation include pedicle width (PW), pedicle transverse angle (PTA), pedicle angle measured from the entry point of Roy-Camille through the midpoint of the pedicle (PPA), screw insertion depths to the anterior cortex from the entry point of Roy-Camille along the line parallel to the midsagittal line (PPLP) and from the entry point of Magerl along the pedicle axis (PPLS).

RESULTS

The mean age of the volunteers was 46.2 years. The average PWs from L2 to S1 were: 0.85 +/- 0.15 cm for L2, 0.92 +/- 0.22 cm for L3, 1.19 +/- 0.24 cm for L4, 1.70 +/- 0.28 cm for L5 and 2.31 +/- 0.35 cm for S1. The average PTAs from L2 to S1 were: 13.9 degrees +/- 4.9 degrees for L2, 13.4 degrees +/- 5.1 degrees for L3, 16.2 degrees +/- 5.9 degrees for L4, 27.8 degrees +/- 7.2 degrees for L5 and 44.0 degrees +/- 8.4 degrees for S1. The average PPAs from L2 to S1 were: 5.3 degrees +/- 2.4 degrees for L2, 6.3 degrees +/- 2.2 degrees for L3, 7.2 degrees +/- 2.5 degrees for L4, 10.1 degrees +/- 3.6 degrees for L5 and 17.0 degrees +/- 4.8 degrees for S1. The average PPLPs from L2 to S1 were: 5.64 +/- 0.82 cm for L2, 5.05 +/- 0.62 cm for L3, 4.99 +/- 0.89 cm for L4, 4.42 +/- 0.77 cm for L5 and 4.23 +/- 0.72 cm for S1. The average PPLSs from L2 to S1 were: 5.75 +/- 0.72 cm for L2, 5.24 +/- 0.75 cm for L3, 5.27 +/- 0.84 cm for L4, 4.88 +/- 0.72 cm for L5 and 4.99 +/- 0.72 cm for S1.

CONCLUSIONS

Transpedicular screw fixation should be tailored on individual basis. Though variation exists, no sufficient evidence can be found to suggest major morphometric differences of the Chinese lumbar pedicles from the studies in the English literature.

Peritoneopericardial communication after pericardiocentesis in a patient on continuous ambulatory peritoneal dialysis with dialysis pericarditis

A male patient aged 41 years had dialysis pericarditis with massive pericardial effusion in his 6-year on continuous ambulatory peritoneal dialysis (CAPD). Intensive hemodialysis failed to resolve the pericardial effusion. Pericardiocentesis via a subxiphoid approach was performed with placement of a pigtail catheter for drainage. A communication between peritoneal and pericardial cavities occurred, resulting in the leakage of the peritoneal dialysate into pericardial sac which was confirmed by a 99mTc radionuclide scan. The fistula healed after removal of the catheter and discontinuation of CAPD. We suggest that pericardiocentesis via a subxiphoid approach for pericardial effusion should be cautiously exercised in CAPD cases for fear of peritoneopericardial fistula.

Blood pressure response to angiotensin converting enzyme inhibitor in essential hypertension: its relation to the renin status and natriuresis during acute sodium loading

We examined the antihypertensive response to enalapril and its relation to the changes of the renin-angiotensin-aldosterone axis (RAA) in essential hypertensive patients. The responders, whose blood pressure reduced after enalapril administration, had significant elevation of plasma renin activity after enalapril (7.5 +/- 4.0 to 31.9 +/- 10 ng/mL/h, p < 0.05). There was no significant change in the plasma renin activity of the nonresponders (3.0 +/- 1.0 to 5.6 +/- 1.9 ng/mL/h). Natriuretic response to acute salt loading was compared between the two subgroups. The natriuresis on acute salt loading of nonresponders was better than that of the responders (82.9 +/- 13.2 vs 44.5 +/- 5.7 mmol/4h, p < 0.05). These results imply that the RAA and extracellular fluid volume both contribute in different ways to the maintenance of high blood pressure in different subgroups of essential hypertension.