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Biomedical subjects

H Kienapfel

Publications and source records attributed to H Kienapfel.

At least 19 recordsLinked to original sources
PubMed2004

The effect of Palamed G bone cement on early migration of tibial components in total knee arthroplasty.

OBJECTIVE: Migration of the tibial component in total knee arthroplasty (TKA) is subject of many studies using roentgen stereophotogrammetric analysis (RSA). In previous studies of cemented and uncemented tibial components, high migration values were found. Improvements in cementing technique, prosthetic design and pre-coating techniques reduced these values as shown in more recent studies. MATERIAL AND SUBJECTS: A total of 35 patients were initially included in the study and operated on between 12/1999 and 10/2000. All patients received a NexGen TKA cemented into the proximal tibia using Palamed G bone cement. The implants and the tibial metaphysis were marked with standard tantalum markers. Radiostereometric analysis was performed post-operatively and after 3, 6 and 12 months using a standard digital radiostereometric analysis. Functional parameters were assessed using the Knee Society Score (KSS) clinical rating system. RESULTS: There were no complications and failures within the first year. After 1 year radiostereometric measurements of the translational parameters along and the rotational parameters around the x-, y- and z-axis revealed: X-Trans -0.19 mm, Y-Trans +0.02 mm, Z-Trans +0.08 mm, X-Rot +0.26 degrees, Y-Rot -0.35 degrees, Z-Rot +0.09 degrees. The maximum total point motion was +0.96 mm and the mean maximum subsidence was -0.23 mm. Except for anterior-posterior, medio-lateral stability and extension leg all endpoints of the KSS clinical rating system showed a significant improvement. CONCLUSIONS: After 12 months, the use of Palamed G bone cement in total knee arthroplasty was demonstrated to be safe. Both the clinical and radiostereometric results were good and comparable to the results reported in other RSA studies in cemented total knee arthroplasty.

Aged↗
PubMed2003

[Effect of rotation of the femoral and tibial components on patellofemoral malalignment in knee arthroplasty].

Patellofemoral complications are among the most common causes for revision surgery in total knee arthroplasty. So far no quantitative assessment has been made of the femoral and tibial malalignment or the positioning of the patellar component and the type of patellofemoral complication or failure. In particular, no comparative studies are available that include patients with and without patellofemoral failure in respect to the above-mentioned parameters when implant material, implant design, and fixation technique were identical. Between 1985 and 1992, 171 MG I total knee arthroplasties were performed. Since 1999, 20% of all the implanted MG I knee arthroplasties (all with metal-backed patellar component) had to be revised. Of those 34 patients, 18 were pair matched with 18 control patients based on the criteria of sex, body mass index, and age. The only difference in the control group was that they did not suffer any malfunction of the patellofemoral mechanism. To assess the patella component localization, conventional AP radiographs, patellar merchant view radiographs in 30 degrees, and CT scans were performed. This study has demonstrated a significant difference for the thickness of the patellar component and a trend regarding the rotational malalignment of the tibial component. Potential causes for the malrotation and guidelines to prevent rotational malalignment are discussed.

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PubMed2003

[What effect does the hydroxyapatite coating have in cementless knee arthroplasty?].

The goal of this study was to compare the migration of noncemented diffusion sintered titanium fibermesh-coated tibial components with (HA group) and without (non-HA group) additional hydroxyapatite coating. For this purpose digital radiostereometry (DIRSA) was used to compare the migration after 2 and 9 years for the two groups. After 2 years the mean maximum subsidence of the HA-coated components (0.24+/-0.18 mm) was about one-half of the mean maximum subsidence of the non-HA-coated group (0.55+/-0.55 mm). After 9 years the maximum subsidence of the HA-coated components was still smaller, but not as pronounced as before. The same trend was also found for the endpoint maximum total point motion (MTPM). After 2 years the mean MTPM of the HA-coated components was 0.66+/-0.38 mm and of the non-HA group 0.73+/-0.50 mm. After 9 years the mean MTPM for the HA-coated components was 0.54+/-0.15 mm and for the non-HA-coated components 0.74+/-0.20 mm. None of the HA-coated tibial components but one of the non-HA group had to be revised and exchanged due to aseptic loosening.

Aged↗
PubMed2001

Cell differentiation under the influence of rh-BMP-2.

Bioactive bone growth factors will likely play an important role in the regeneration of bone. BMP-2 is known to promote osteoblastic cell differentiation and osteogenesis. Whether the BMPs act on human osteoblastic cells by increasing immature cell growth and/or differentiation is unknown. The goal of this study was to analyse possible effects of rhBMP-2 on cell differentiation using a human bone marrow cell culture. rhBMP-2 was added to the culture medium once. Fourteen days after addition of rhBMP-2 the cells were incubated with monoclonal antibodies. The cells were counted and analysed in a fluorescence-activating cell sorter (FACS). Compared to the controls there was an increasing effect on granulocytes, B cells and stem cells. The T-cells and monocytes show no increase or decrease after rhBMP-2 treatment.

Adult↗
PubMed2000

Missing osteoconductive effect of a resorbable PEO/PBT copolymer in human bone defects: a clinically relevant pilot study with contrary results to previous animal studies.

PEO/PBT 70/30 (POLYACTIVE(R) 70/30), a degradable porous copolymer with elastic properties, was found to be osteoconductive in many animal studies. The aim of this study was to determine the osteoconductive effect in a human paired control iliac defect model. In seven patients undergoing anterior spinal interbody fusion surgery, two bicortical iliac defects for autograft harvesting were created. The defect size was identical for both defects measuring about 40 x 15 mm (group I). One defect was filled with the degradable implants, whereas the remaining one was left untreated as a control. The defect site for treatment was chosen randomly. In three further patients, only one defect measuring about 40 x 35 mm was created (group II). All patients were examined clinically and radiologically by spiral-CT after 1, 6, 12, 24, and 52 weeks. Three-dimensional reconstructions as well as CT-volumetric measurements using 1 mm sections were used as evaluation methods. In group I, a two-tailed paired t-test showed that the treated defects had significantly less formation of new bone than the untreated ones (p < 0.05 after 12 weeks, p < 0.01 after 52 weeks). Also, in group II, not much bone ingrowth could be observed. The histological evaluation of one patient in group I revealed no bone within the pores, and a fibrous layer between bone and implant was always present. Therefore, PEO/PBT 70/30 cannot be recommended as a bone substitute for clinical use. Differences in bone regeneration between humans and certain animal species as well as inapplicable defect models in previous animal studies are discussed as possible reasons for the failure.

Animals↗
PubMed1999

[A scale for measuring symptoms related to degenerative diseases of the cervical spine. A reference in determining indications and evaluating surgical outcome].

A scale for measuring symptoms related to degenerative diseases of the cervical spine is presented. Twenty typical symptoms are listed, e. g., neck pain, dysesthesia, and reduced mobility. Responses are assessed via a 6-point scaling ("did not have symptom" - "had symptom and suffered very strongly".) The cervical spine scale was tested in three samples: patients having undergone cervical spine surgery (n = 70), patients with other orthopedic diagnoses (n = 104), and healthy students (n = 100). The single items of the scale were aggregated into four scores: total number of symptoms, degree of overall symptom distress, functional disability, and pain/psychological distress. Statistical analyses proved the high reliability (Cronbach's alpha = 0.85 to 0.95) and validity (content, convergent, discriminant) of all scores. The scale differs clearly between cervical spine patients, other orthopedic patients and healthy individuals, and between cervical spine patients with different subjective operative outcomes. For applied clinical purposes the cervical spine scale can be included in a quality of life profile (QL-profile); this allows for a readily understandable graphic depiction of individual patients' QL-status.

Activities of Daily Living↗
PubMed1999

Prevention of heterotopic bone formation after total hip arthroplasty: a prospective randomised study comparing postoperative radiation therapy with indomethacin medication.

Heterotopic ossification (HO) after total hip arthroplasty is known to be a major complication with an impact on the functional outcome. Efforts have been made to prevent the occurrence of HO by means of either radiation therapy or pharmacotherapy. To date, there are no data available regarding the relative benefit of radiation versus medication with non-steroidal anti-inflammatory drugs. The objective of this study was to compare single-dose 600-cGy radiation therapy with indomethacin medication for their effect on the prevention of heterotopic bone formation after total hip arthroplasty. In all, 154 patients were included in the study. All patients underwent primary total hip arthroplasty due to osteoarthritis. Patients were randomly assigned to three different therapeutic groups. (a) The radiation group received a single radiation dose of 600 cGy between the 2nd and 4th postoperative day. (b) The indomethacin group received an oral application of indomethacin 2 x 50 mg per day from the 1st to 42nd postoperative day. (c) The control group received neither radiation nor indomethacin medication. There were significant group differences (P < 0.001). A least significant difference test (LSD) revealed that the mean of the control group was significantly different from that of the radiation and indomethacin groups. The 13 patients (8.4%) classified Brooker 3 or 4 were all in the control group. Again, this effect was statistically significant (chi-square, P < 0.001). In conclusion, this study demonstrated that both radiation and indomethacin therapy are effective in the prevention of postoperative HO. The choice for either one of the treatments has to be based on availability, contraindications, side-effects, practicability, standardisation and cost. Based on these considerations together with the results of this study, we currently use postoperative radiation with 600 cGy for all patients undergoing primary total hip arthroplasty.

Administration, Oral↗
PubMed1999

Implant fixation by bone ingrowth.

The term osseointegration referred originally to an intimate contact of bone tissue with the surface of a titanium implant; the term bone ingrowth refers to bone formation within an irregular (beads, wire mesh, casting voids, cut grooves) surface of an implant. The section dealing with the historical background describes the development of macroporous, microporous, and textured surfaces with an emphasis on the evolution of porous and textured metal surfaces. The principal requirements for osseointegration and bone ingrowth are systematically reviewed as follows: i) the physiology of osseointegration and bone ingrowth, including biomaterial biocompatibility with respect to cellular and matrix response at the interface; ii) the implant surface geometry characteristics; iii) implant micromotion and fixation modes; and iv) the implant-bone interface distances. Based on current methods of bone ingrowth assessment, this article comparatively reviews and discusses the results of experimental studies with the objective of determining local and systemic factors that enhance bone ingrowth fixation.

Animals↗
PubMed1998

Biocompatibility analysis of different biomaterials in human bone marrow cell cultures.

A cell culture system for biocompatibility testing of hip implant materials is described. Human bone marrow cells have been chosen because these cells are in direct contact with the biomaterial after implantation in situ. The sensitivity of this method is evaluated for materials which are already being used as implants in humans and animal, e.g., hydroxyapatite (HA) ceramic, pure titanium, and ultra-high-molecular-weight polyethylene (UHMWPE). As indicative parameters of biocompatibility primary cell adherence, cell number, cell proliferation, production of extracellular matrix, cell vitality, and cell differentiation are described. After 2 weeks in culture, obvious differences between the biomaterials with respect to the indicative parameters could be observed. Cell numbers were greatest on the HA specimens. In the case of titanium alloys, we observed a decreased number of cells. The production of extracellular matrix was high for the HA ceramics but reduced for titanium specimens. The polymers allowed only a few adherent cells and showed no signs of extracellular matrix production. The results can be correlated astonishingly well to animal experiments and clinical experiences. Therefore, we suggest that this cell culture system seems to be a useful tool for biocompatibility testing of bone implantation materials. It also helps reduce animal experiments. With the help of flow cytophotometry, we analyzed the influence of biomaterials on large numbers of cells with respect to differentiation. There were similar populations of T cells and monocytes on all specimens tested. Extended B-cell and granulocyte populations, however, were observed with titanium and UHMWPE. Most osteocalcin-containing cells adhered to the HA ceramics.

Aged↗
PubMed1997

Recombinant and nonrecombinant factor XIII and its effect on bone ingrowth and strength of fixation.

Thirty cylindrical, commercially pure, titanium fiber, porous-coated Ti6Al4V implants were inserted press-fit into the proximal humeral portion of 30 sheep humeri to determine the systemic effect of recombinant factor XIII and placenta-derived factor XIII concentrate on bone ingrowth and strength of fixation. For both the recombinant factor XIII and the factor XIII concentrate group, the volume of bone ingrowth and the strength of fixation were higher than for the control specimens. However, the difference was only significant for the factor XIII concentrate group.

Animals↗
PubMed1996

Standardized evaluation of long-term results after anterior lumbar interbody fusion.

A total of 113 patients, excluding those with tumor, spondylitis, and idiopathic scoliosis, underwent anterior lumbar interbody fusion (ALIF) with autologous iliac crest graft between 1984 and 1991 at our department. The proportion of these who were failed back patients was higher than that reported in the literature. Evaluation of functional outcome was feasible in 80 patients, utilizing Oswestry and Marburg scores, which were closely intercorrelated. The overall results yielded an improvement in the Oswestry score of 35.7 percentage points. A subset of 52 patients who were evaluated twice, showed the same results at an average of 6.6 years as they did at 2.3 years following surgery. Functional results showed a weak correlation with postoperative height loss of the intervertebral space. Influencing factors for the functional result were: postoperative compensation claim, age, and obesity. Of the professional people involved, 19.4% did not return to any occupation. Patients satisfied with the result had significantly greater functional improvement. Younger patients with additional dorsal distraction prior to ALIF for reduction of severe spondylolisthesis fared better than patients with ALIF alone. The rate of complications was low and did not contribute to the postoperative functional result. On the basis of these results further prospective studies have been designed and are currently underway.

Adolescent↗
PubMed1995

Bone ingrowth and wear debris in well-fixed cementless porous-coated tibial components removed from patients.

Bone ingrowth and the distribution of wear debris within the porous coating of 13 primary cementless porous-coated tibial components removed for reasons unrelated to fixation or infection were quantitatively described. The average length of implantation was 15.3 months (range, 3-30 months). The implants were all of the same design, made for Ti6A14V with a commercially pure titanium fiber-metal porous coating, which covered the undersurface of the tray and the four fixation pegs. In all but one component, supplemental screw fixation was used. The average extent of bone ingrowth within the tray was 27.1 +/- 16.1%, and the average volume fraction was 9.5 +/- 7.5%. There was significantly more bone ingrowth within the fixation pegs than within the tray and also more bone ingrowth in the anterior half of the tray than posteriorly. There was no correlation between the amount of bone ingrowth and the length of implantation, age, or sex of the patient; however, the depth and orientation of the resection plane were found to correlate with the topographic distribution of bone ingrowth. Particulate debris appeared to gain access to the interface via soft tissue pathways both at the periphery and through the holes for adjuvant screw fixation.

Alloys↗
PubMed1992

Efficacy of autograft and freeze-dried allograft to enhance fixation of porous coated implants in the presence of interface gaps.

Autogenous cancellous bone and freeze-dried allogeneic cancellous bone were tested in a total of 41 adult male mongrel dogs. In each humerus, an implant with a commercially pure titanium fiber metal porous coating was placed in an overreamed cavity so that a uniform 3-mm gap was present between the implant and host cancellous bone. Graft material was placed in the gap of one humerus while the gap of the other humerus was left empty and served as a paired negative control. Histologically, both autograft and allograft appeared to aid repair of the defect, but quantitatively only autograft enhanced new bone formation within the defect. Treatment with autograft significantly increased the amount of bone ingrowth within the implants by nearly three-fold at 4 weeks and eight-fold at 8 weeks. The enhancing effect was recognizable as early as 2 weeks. The strength of fixation was increased by nearly seven-fold at 4 weeks and two-fold at 8 weeks in the autograft group, but this was only statistically significant at 4 weeks. Treatment with allograft did not enhance bone ingrowth at any time period, but had a small positive effect on strength of fixation at 4 weeks.

Analysis of Variance↗
PubMed1992

Three- to five-year results with the cementless Harris-Galante acetabular component used in hybrid total hip arthroplasty.

In this paper we present our 3- to 5-year results after hybrid total hip replacement using the cementless porous coated Harris-Galante acetabular component and the cemented Griss femoral component in 39 patients with 40 implantations. Postoperatively, mild to moderate pain was experienced by 16.1% of patients, mostly following hard activity. A slight to moderate limp occurred in 24.2%. All patients were able to walk more than 1000 m. Full-time use of support was required by 2.8%. The postoperative range of motion was increased in 93.9%. Radiographically, none of the acetabular or femoral components had to be classified as unstable. Only one acetabular component displayed complete (i.e., along all interface zones) radiolucency and was therefore classified as possibly unstable.

Acetabulum↗
PubMed1992

[Morphological and numerical studies of the stress compatibility of patella implants].

Failure of total knee arthroplasty is relatively often caused by problems of the patellofemoral replacement. The purpose of this study was to analyze the distribution of stresses within an anatomical patella and the changes in stress distribution after patellar resurfacing with a Miller-Galante I patellar implant using two- and three dimensional finite element models (FEM). To assess validity, FEM results were compared with morphological findings from contact radiographs and densitographs. Internal orientation of bone trabeculae is in good agreement with the orientation of theoretically calculated principal stresses. Almost unchanged principal tensile stresses after implantation, together with the lack of extreme stress peaks within the cancellous bone ensure stress compatibility of the implant. In the case of a firmly seated implant with good bone ingrowth, increased von Mises stresses are found near the fixation peg/plate junction. Their relevance for improved bone ingrowth near this part of the interface is emphasized. At the same time, material failure at the peg/plate junction can be better understood. An analysis of the early postoperative period assuming nonlinear interface conditions failed to demonstrate an uniform distribution of normal and tangential interface forces.

Aged↗
PubMed1991

Cementless Gustilo-Kyle and BIAS total hip arthroplasty: 2- to 5-year results.

We conducted extensive radiographic and clinical examination of 58 cementless total hip arthroplasties. Forty BIAS femoral stems had heads made of Co-base F 75 alloy and 18 Gustilo-Kyle femoral stems had Ti6A14V alloy heads. The cross-sectional geometry and location of the porous coating pads of the two stem types was identical, the BIAS component being slightly shorter. At the last follow-up, 27.8% of the Gustilo-Kyle femoral components and 2.5% of the BIAS femoral components were unstable. None of the acetabular components in the BIAS group as against 38.9% of the acetabular components in the Gustilo-Kyle group demonstrated wear of more than 1 mm. All unstable components which did not suffer intraoperative fracture had also acetabular wear of more than 1 mm. The only case with endosteal erosion was seen in a patient with an unstable implant displaying the most extensive wear. Nonparametric statistical analysis showed that the patients with Ti6A14V/polyethylene bearing surfaces had a statistically significantly higher extent of wear and a statistically significant higher incidence of femoral component loosening than patients with CrCoMo/polyethylene bearing surfaces.

Adult↗
PubMed1991

[2- to 5-year follow-up of cementless implantable knee joint prosthesis of the Miller-Galante type].

Based on a prospective study protocol, the two- to five-year results of the Miller-Galante cementless total knee arthroplasty are presented. Sixty-four implants were placed in 59 patients: 60 implantations were cementless and 4 cemented. Clinically, the scores for pain, range of motion, walking and stair climbing improved significantly. Radiographically, the uncemented components displayed no signs of definite or possible loosening, whereas one of the cemented components was found to be definitely loose. On histological evaluation of the retrieved implants, all components had bone ingrowth.

Aged↗