Biomedical subjects

Zhinian Wan

Publications and source records attributed to Zhinian Wan.

11 recordsLinked to original sources

PubMed2006

Precision and limitation of measuring two-dimensional wear on clinical radiographs.

The precision of measuring polyethylene penetration in total hip arthroplasties has been studied using phantom models and retrieved cups, but not on radiographs obtained in vivo. We used Hip Analysis Suite Hip32 computer software to measure two-dimensional penetration in two groups of anteroposterior pelvic radiographs taken in vivo. We determined the measurement error for precision, the effect of position change on precision, and compared direct and indirect measurements. The influences on precision with respect to followup time were measured using a separate group of radiographs. Precision was 0.89 to 1.16 mm and decreased as more variables were added. The direction of wear was toward the contact surface of the cup in greater than 50% of patients with more than 5 years followup. Negative wear severely affected precision in 40% to 50% of patients. Individual penetration measurements were unreliable when total penetration was low (< 1.1 mm). The two-dimensional computer technique has limitations when measuring such low wear. Measurement errors were caused by slight radio-graphic distortions of the femoral head and acetabular component and by blurred edges on some clinical radiographs.

Adult↗

PubMed2005

Total hip arthroplasty with the APR stem and cup follow-up of a previous report.

The 2- to 5-year results of the APR-II total hip arthroplasty system (APR-II, Zimmer, Warsaw, Ind) were previously reported for 107 consecutive total hip arthroplasties performed between January 1994 and January 1995. The purpose of this study was to report the 10-year survival data in this same cohort of patients. Seventy-two (73%) of the 99 hips originally studied met the inclusion criteria for this report. None of the femoral or acetabular components had radiographic or clinical loosening. Three hips had had revision surgery for the acetabulum with 2 for recurrent dislocation and 1 for liner disassociation. All femoral components were retained. The 10-year Kaplan-Meier survivorship analysis, with failure defined as mechanical loosening, was 100% for both the cup and stem. These hip replacements have not shown any postoperative deterioration of clinical result, fixation, or wear up to 10 years.

Adult↗

PubMed2005

Operative and patient care techniques for posterior mini-incision total hip arthroplasty.

UNLABELLED: Technical and patient care improvements have occurred with the posterior mini-incision total hip arthroplasty. We hypothesized that these changes would provide better results for patients. The clinical and radiographic results of 100 total hip arthroplasties done with the posterior mini incision between January 2004 and October 2004 were compared with 100 mini-incision total hip arthroplasties done between December 2001 and September 2002. There were no differences in diagnosis, age, and body mass index of the patients in each group. Component positions were not compromised in either group. There were improvements in the 2004 group with decreased hospital stay, reduction of postoperative pain and opioid analgesic use, reduced use of assistive devices, and earlier muscle recovery. In the 2004 group there were no complications of infection, dislocation, or sciatic palsy. The posterior mini-incision operation has shown improved results with experience and changes in technique and patient care treatment. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗

PubMed2005

Clinical performance of a Durasul highly cross-linked polyethylene acetabular liner for total hip arthroplasty at five years.

BACKGROUND: Highly cross-linked polyethylene is currently the most common articulation surface used for total hip arthroplasty. The hypothesis of the present study was that the Durasul highly cross-linked polyethylene acetabular liner would have less wear at five years than would a conventional polyethylene liner used in association with the same total hip replacement system. METHODS: Forty-three consecutive patients (fifty hips) underwent total hip replacement with an uncemented titanium porous-coated metal cup and a Durasul liner that was mated with a 28-mm cobalt-chromium femoral head. Thirty-one patients (thirty-seven hips) were followed for at least five years. Thirty-five other patients (thirty-seven hips) underwent total hip arthroplasty with the same system but with a conventional polyethylene liner, and these patients also were followed for five years. Clinical assessment was performed with use of the Harris hip score and a patient self-assessment examination. Radiographic analysis included measurements of acetabular component position, fixation, and osteolysis. Femoral head penetration of the Durasul liners was compared with that of the conventional liners. RESULTS: The clinical results as determined on the basis of Harris hip scores and patient self-assessment examinations did not differ between the Durasul group and the control group. The mean bedding-in penetration was 0.054 +/- 0.07 mm for the Durasul group and 0.059 +/- 0.154 mm for the control group. The subsequent penetration, with elimination of the bedding-in wear, resulted in a linear wear rate of 0.029 +/- 0.02 mm per year for the Durasul group, compared with 0.065 +/- 0.03 mm per year for the control group (p < 0.005). The annual penetration at one and five years was 0.074 mm and 0.011 mm, respectively, for the Durasul group, compared with 0.151 mm and 0.04 mm, respectively, for the control group. CONCLUSIONS: While the qualitative wear pattern of the highly cross-linked polyethylene liner was the same as that of the conventional polyethylene liner, the annual linear wear rate was 45% of that seen with the conventional polyethylene liner. Therefore, we believe that these early data support the continued use of this highly cross-linked polyethylene liner for total hip arthroplasty.

Adult↗

PubMed2005

Development of imageless computer navigation for acetabular component position in total hip replacement.

The purpose of this study was to develop an imageless (without preoperative computerized tomography (CT) scans or intraoperative fluoroscopy) computer navigation system for total hip replacement. One-hundred and ninety-five hips were operated with imageless computer navigation. Eighty-five hips were operated prior to obtaining precise results, with precision refined in the subsequent 110 hips. Computer accuracy for cup-adjusted anteversion was achieved in 100% of the final 40 hips, and for adjusted inclination in 96.6%. The factors necessary for accurate measurements are mechanical stability of the tools with the light-emitting diodes, adjusted computer anteversion and inclination for the tilt of the pelvis (tilt in the AP plane), and check-and-balance techniques for confirmation of measurements of tilt, anteversion and inclination.

Acetabulum↗

PubMed2004

Fixation and osteolysis with Metasul metal-on-metal articulation.

The purpose of this study was to report the prevalence of osteolysis and loss of fixation using Metasul metal-on-metal articulation couples. Ninety-two patients with 96 hips with Metasul articulation couples were followed for 5 to 11 years. By patient self-assessment, 89 (93%) patients scored themselves as good or excellent. The occurrence of osteolysis and the grading of fixation were obtained from plain radiographs. The clinical evaluation for these patients was performed by patient self-assessment. With the use of plain radiographs, there was no osteolysis observed in these 96 hips other than calcar resorption (6 hips [6.3%]). All components were fixed, except for 1 loose cup that was revised, and this level of fixation allowed a fair evaluation for osteolysis around well-functioning implants.

Adult↗

PubMed2004

Assessment of bone graft substitutes in autopsy implant retrievals of the acetabulum in total hip arthroplasty.

Two autopsy retrievals of acetabular reconstruction with different bone graft substitutes were analyzed. One patient underwent surgery with hydroxyapatite (HA) granules, and the other with demineralized bone chips. Incorporation occurred with the biomaterial bone-graft substitute HA primarily in the superior part of the acetabulum, where the HA was in contact with host cortical bone. No bony union occurred with the demineralized bone chips because of motion and migration of the acetabular cup. No bone incorporation of either bone-graft substitute was observed in the medial wall defects in both patients. There were two important findings: (1) the 3- to 8-mm depth and 70% to 75% surface of union of the HA bone graft substitute to host cortical bone was the same as seen with morselized, fresh-frozen bone graft; and (2) union of graft material to host bone was dependent on secure fixation of the acetabular construct.

Acetabulum↗

PubMed2004

The argument for the use of Metasul as an articulation surface in total hip replacement.

Metasul metal-on-metal articulations have been used for 15 years in approximately 300,000 total hip replacements. We have used Metasul articulations in three clinical studies and have shown clinical success as measured by Harris hip scores and patient self-assessment; we also have had the usual mechanical complications. The only complications have been mechanical, including two cup loosenings and 24 dislocations in a total of 582 patients (619 hips; 3.8%) who had Metasul articulations and were included in these studies. In the randomized study, the group who had Metasul articulations had no clinical results or complications different from the control ceramic-on-polyethylene group. Authors of retrieval results in the literature report low annual linear wear rates and no consequences of elevated Co ion levels. Currently, the scientific evidence of the results of using the Metasul articulation would recommend its continued use in any patient who does not have compromised renal function.

Adult↗

PubMed2004

Comparison of proximal porous-coated and grit-blasted surfaces of hydroxyapatite-coated stems.

BACKGROUND: It remains controversial whether a proximal porous coating is superior to a grit-blasted surface with regard to providing femoral stem fixation in total hip arthroplasty. We examined the hypothesis that a proximal porous coating would provide better fixation than would a fully grit-blasted surface of otherwise identical proximally hydroxyapatite-coated stems. METHODS: In a prospective study, seventeen patients (thirty-four hips) underwent bilateral sequential total hip replacement with the Anatomic Porous Replacement at the same operation. A proximally porous-coated femoral stem was implanted on one side, and a stem of the same design but with a proximal grit-blasted surface was implanted in the contralateral hip. A proximal hydroxyapatite coating was applied to the metallic substrate of both stems. The patients were followed for a mean 2.5 years and then were assessed radiographically and clinically with the Harris hip score. RESULTS: With the numbers available, no significant clinical or radiographic differences were found between the two cohorts. Thirty of the thirty-four hips had an excellent result, two were rated good, and two were rated fair. All hips had stable osseous fixation of the stem radiographically. The two types of stems were associated with the same pattern of adaptive bone-remodeling. CONCLUSIONS: In the first two years following total hip arthroplasty, hydroxyapatite-coated proximally porous-coated femoral stems do not provide fixation that is superior to that provided by hydroxyapatite-coated grit-blasted stems. LEVEL OF EVIDENCE: Therapeutic study, Level II-1 (prospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

Adult↗

PubMed2002

Polyethylene liner cementation into fixed acetabular shells.

A patient presenting with a secure cementless acetabular component and with femoral head penetration through the polyethylene liner is a common clinical problem. Cementing a new liner into the fixed shell is one option. We evaluated this option in a clinical series of 17 cases and with a preliminary mechanical study. In the 1 clinical failure (5.9%), the failure occurred at the cement-liner interface. The most important variable in optimizing the mechanical strength of the cemented liner construct was adequate preparation of the cement-liner interface. This approach to treating the patient with a fixed cementless shell and a worn polyethylene liner can provide a durable construct with minimal morbidity.

Aged↗

PubMed2002

Cementless hemispheric porous-coated sockets implanted with press-fit technique without screws: average ten-year follow-up.

BACKGROUND: Press-fit implantation of a porous-coated hemispheric acetabular component without screws is an option for primary total hip replacement. The purpose of the present study was to evaluate the results of this technique after an average duration of follow-up of ten years to determine if there was any loss of fixation or increase in osteolysis over time. METHODS: From June 1988 to November 1990, 132 primary total hip replacements were performed with a porous-coated socket that was implanted with use of a press-fit technique. Twenty-two hips were excluded because the patient had died or had been lost to follow-up, leaving 110 hips (103 patients) available for inclusion in the study after an average duration of follow-up of 10.2 +/- 1.0 years. The average age of the patients at the time of operation was 60.7 years (range, 23.7 to 86.2 years). Radiographs were evaluated with regard to initial gaps, radiolucent lines, migration, polyethylene wear, and osteolysis. Kaplan-Meier survivorship analysis was performed to calculate the rate of survival of the acetabular component. RESULTS: One hip (0.9%) had revision of the socket because of aseptic loosening, and four hips (4%) had revision of a stable socket. With the numbers available, the presence of gaps on the initial postoperative radiographs was not associated with the occurrence of radiolucent lines (p = 0.039). Pelvic osteolysis was seen in four hips, with an average time to radiographic appearance of six years. Increased wear was directly related to an abduction angle of >40 degrees. The twelve-year survival rate was 99.1% with revision because of failure of fixation of the metal shell as the end point, 95.3% with revision for any reason as the end point, and 79.6% with exchange of the liner as the end point. CONCLUSIONS: The fixation of this press-fit socket did not deteriorate over time and was associated with a low rate of osteolysis. The most common reasons for reoperation were wear and dissociation of the polyethylene insert.

Adult↗