Biomedical subjects

P Griss

Publications and source records attributed to P Griss.

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↗

PubMed2004

Safety and efficacy of unmodified whole blood vs. buffy coat-depleted red cell concentrates in autologous transfusion of elective orthopaedic surgery patients.

Storing autologous blood as whole blood (WB) has been proposed for increasing the cost-effectiveness of preoperative autologous blood donation programmes. However, experimental data suggest that autologous leucocytes might lead to immunomodulation similar to the effect attributed to allogeneic leucocytes. In a retrospective analysis, the postoperative outcome of 120 patients undergoing elective orthopaedic surgery and having donated up to two units of autologous WB (AWB) was compared with that of a control group of 52 patients, whose autologous donation had been processed into buffy coat-depleted red cell concentrates (RCC). At least one autologous unit, but no allogeneic units, had been transfused in all analysed patients. Donation schemes were equally efficacious in both groups. There was no significant difference in postoperative infection rates between the two groups. Overall rates were 7.7% in the RCC group and 8.3% in the WB group. Surgical, thromboembolic and other recorded complications, length of postoperative hospital stay and days of the use of antibiotics were also not significantly different between the two groups. The results of this study suggest that transfusion of up to two units of unmodified AWB is as efficacious as the transfusion of autologous RCC and does not negatively influence the postoperative outcome in elective orthopaedic surgery.

Blood Component Transfusion↗

PubMed2004

[Electrospun poly-l-lactide nanofibres as scaffolds for tissue engineering].

Tissue engineering is a promising tool for treating structural and functional defects in bone and cartilage. To provide optimal conditions for three-dimensional cell growth the use of a scaffold is necessary. The aim of the study was to test the potential application of an electrospun poly (l-lactide)-nanostructured scaffold as a matrix for tissue engineering. Matrices were seeded with human osteosarcoma MG-63 cells and cultivated for 14 days. Cells showed a clear preference for growth along the nanofibres, and demonstrated no signs of degeneration or apoptosis. The fine structure of electrospun nanofibres makes them an ideal scaffold for tissue engineering, in particular for cartilage repair. They can be "doped" with growth factors, medications, etc., and are both biocompatible and biodegradable.

Apoptosis↗

PubMed2003

A comparative clinical outcome evaluation of smooth (10-13 year results) versus rough surface finish (5-8 year results) in an otherwise identically designed cemented titanium alloy stem.

BACKGROUND: We retrospectively compared the influence of surface finish with respect to the long-term durability of a cemented titanium alloy stem of the same design but different surface finish. METHODS: From 1984 to 1994, the stem was made of a titanium-aluminum-vanadium alloy. A total of 201 patients with 220 smooth stems (mean follow-up 11 years and 4 months) out of 612 implanted between 1984 and 1987 and 319 patients with 343 rough stems (mean follow-up 5 years and 10 months) out of 812 implanted between 1991 and 1993 could be reviewed clinically and radiologically for comparison. The average age of the patients with the smooth stem was 58.1 years and of the patients with the rough stem, 62.2 years. In both groups, 35% of patients were male and 65% female. RESULTS: The mean Merle d'Aubigné hip score increased from 10.5 to 16.0 points in the smooth stem group and from 11.0 to 16.9 points in the rough stem group. The distribution of radiolucent lines, according to the zones of Gruen, was similar in both groups. The smooth stem required revision in 18 cases after a mean follow-up of 11 years and 4 months and the rough stem in 30 cases after a mean follow-up of 5 years and 10 months. The survival analysis (Kaplan-Meier) revealed 95.4% survival after 13 years for the smooth femoral component and 76.7% survival after 8 years for the rough femoral component. CONCLUSIONS: The implantation of titanium alloy stems with a rough surface finish cannot be recommended because of its high aseptic loosening rate.

Alloys↗

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.

Aged↗

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↗

PubMed2002

The blood supply of the growth plate and the epiphysis: a comparative scanning electron microscopy and histological experimental study in growing sheep.

The blood supply of the growth plate has been described in the late 50s and early 60s, and there was controversial discussion about the existence of transphyseal vessels. The vascular supply of growth plate and epiphysis of the proximal tibia was reinvestigated using a modern technique, the Mercox-perfusion method, in six sheep aged 6-24 weeks. A comparison was made among pure perfusion specimens, the corrosion casts, and histological sections. The metaphyseal, epiphyseal, and perichondral blood supply systems were confirmed. However, there was evidence of regular transphyseal anastomoses between the metaphyseal and epiphyseal system. Based on the histological arrangement of the blood vessels, the arterial blood flow would appear to be from the metaphysis to the epiphysis. The existence of transphyseal arterial vessels originating metaphyseally and seen both in cast preparations and histological sections was added to the present description of the blood supply of the growth plate. Age-related differences in the vascularization of the growth plate were not found in this study.

Animals↗

PubMed2002

[Effect of extracorporeal shockwave therapy on vascular regulation. Infrared thermography in epicondylitis humeri radialis].

BACKGROUND: Extracorporeal shockwave therapy (ESWT) is recommended as an alternative treatment for lateral epicondylitis (LE). An influence on the blood perfusion is considered to be one possible effect. Infrared thermography is used in this trial to measure effects of ESWT on the thermal regulation in the target area. METHODS: 33 patients with chronic LE were examined in a prospective, placebo-controlled single blind study with an independent observer. 3 x 2000 impulses of an energy flux density ED+ 0.22 mJ/mm2 were applied under local anaesthesia as verum-ESWT. Placebo-ESWT was performed under the same conditions. One elbow was treated, the other served as control. Before and after each shockwave application and after 12 weeks skin temperature was measured on both elbows at three predefined points by infrared thermography. RESULTS: While a significant decrease in the skin temperature was found on the treated and sham-treated sides opposed to the contralateral side, there was no difference between the real shockwave treatment and placebo therapy. Responder and Non-responder to the treatment could not be distinguished during the therapy. DISCUSSION: Infrared thermography was proved to be a valuable additional technical instrument for diagnosis of LE, but is not an appropriate instrument to predict the clinical outcome in patients treated with ESWT. A noted reduction of skin temperature on the treated side is not due to specific effects of the shockwaves. It is unlikely that ESWT as applied has an influence on thermal regulation in the target area. These findings are supported by negative results of experimental and clinical trials.

Adult↗

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↗

PubMed2001

The long-term (8-12 years) results of valgus and lengthening osteotomy of the femoral neck.

Shortening of the femoral neck and proximal displacement of the greater trochanter are the principal complications following avascular necrosis of the capital epiphysis head in early childhood. We report here the long-term follow-up of a series of osteotomies performed to lengthen the femoral neck and thus to restore the normal anatomy and function of the hip joint. Out of a sample of 24 patients, 15 (62.5%) were reviewed at the end of a mean follow-up of 10 years and 2 months. Fourteen of them (93.3%) had originally complained of pain on walking which varied in severity. After the operation, five were free from pain at the end of the follow-up, 9 still experienced pain on walking, and 1 also reported pain at rest. Before the operation, a positive Trendelenburg's sign was found in 8 of the patients. This was still present in 2 at follow-up. The average perpendicular distance from the center of the femoral head to a horizontal plane passing through the tip of the greater trochanter (the centro-trochanteric distance) was reduced from 33 mm to 7 mm. Apart from correcting the anatomical deformity, it is suggested that this operation may well provide lasting relief from pain and increase the power of the abductor muscles. It may also delay the onset of osteoarthritic change and in this way postpone the necessity for an endoprosthesis.

Adolescent↗

PubMed2001

The influence of intermittent external dynamic pressure and tension forces on the healing of an epiphyseal fracture.

In vitro studies about the regenerative capacity of chondrocytes located in the growth plate of long bones revealed a potential for reparation. A measurable advance in the understanding of the physiologic processes in the bone growth plate and their modifications after defined lesions is based on the recognition of the role of the vascular architecture. Newly formed bridging arteries crossing from the metaphysis to the epiphysis through the growth plate are thought to be responsible for the cell proliferation observed after Salter-Harris I and II lesions. We aimed to examine the influence of mechanical microstimulations on the growth or inhibition of the proliferation of the chondrocytes in the tibial growth plate. We studied 22 tibial bone fractures, which were stabilized with a dynamic or a stable external fixateur. Proliferative changes in the bone tissue were examined by immunohistochemical classification using bromodeoxyuridine (BUdR), a thymidine analogue. Radiologic studies, computer tomography, and magnetic resonance imaging documented the results in comparison with histological examination. Cell proliferation in the growth plate was not stimulated in the 1st week after distraction. The histological studies revealed an initial increase in proliferation of chondrocytes, especially between the 2nd and the 4th week. This was more clearly seen with the use of the dynamic fixator. We conclude that a temporary ischemia with a reactive hyperemia takes place, which we could document by histological analysis and MRI. These results could modify the current clinical therapy of growth plate fractures.

Animals↗

PubMed2001

A new semirigid implant for instrumentation of scoliosis: preliminary report.

A new set of pedicle screws, lamina and pedicle hooks, longitudinal rods and a titanium cable was developed to overcome the increasingly obvious hazards of overly rigid spinal instrumentation. Results of the first 12 consecutive scoliosis patients with this new system are reported, with an average follow-up time of 18 months. No major complications occurred. The average correction of the deformity was well within the range of more rigid systems. The new Dorsal Dynamic Spondylodesis (DDS) system proved to be easy to use, fast, powerful, safe, versatile, and biomechanically sound. Reduction of stress-shielding effects and protection of adjacent segments can be expected, and the system warrants future application in selected prospective cases with long-term follow-up.

Equipment Design↗

PubMed2001

Prevention of venous thromboembolism after knee arthroscopy with low-molecular weight heparin (reviparin): Results of a randomized controlled trial.

PURPOSE: Deep venous thrombosis (DVT) is a common, important complication of major orthopaedic surgery, particularly knee arthroplasty. Knee arthroscopy is increasingly performed on an outpatient basis. Few reports have elucidated the incidence of venous thromboembolism (VTE) in patients undergoing arthroscopic surgery receiving no prophylaxis. The objective of the present trial was to evaluate the risk of VTE in those patients and to determine efficacy and safety of a low-molecular weight heparin (LMWH) in preventing VTE. TYPE OF STUDY: This is the first controlled randomized trial using objective diagnostic methods with blinded outcome assessment to reveal the incidence of VTE in outpatient arthroscopy and determine efficacy and safety of a LMWH (reviparin sodium) in preventing VTE in these patients. METHODS: There were 262 patients undergoing elective knee arthroscopy prospectively randomized to receive either no treatment or reviparin once daily subcutaneously for 7 to 10 days. The blindly assessed primary outcome measure was the incidence of DVT detected by compression color-coded sonography. Both groups were comparable with regard to demographics and baseline characteristics. RESULTS: 239 patients were evaluable (122 no treatment, 117 receiving LMWH). 6 DVT were detected - 5 in the control group (5/117 - 4.1%) and only one in the active treatment group (1/116 - 0.85%). This particular patient had a low level of protein C and a subnormal level of protein S. The odds ratio of 4.95 approximates a relative risk reduction of about 80%. Treatment with reviparin was safe and well tolerated. There was no major bleeding, four patients with minor bleedings. One patient had a transitory fall in platelet count below 100 giga-particles/L without any clinical symptoms. CONCLUSIONS: Patients undergoing knee arthroscopy have a moderate risk of VTE and effective prophylaxis can be achieved with LMWH (reviparin).

Adult↗

PubMed2001

Low-energy extracorporeal shock-wave treatment (ESWT) for tendinitis of the supraspinatus. A prospective, randomised study.

We have performed a controlled, randomised study to analyse the effects of low-energy shock-wave therapy (ESWT) on function and pain in tendinitis of the supraspinatus without calcification. There were 20 patients in the treatment group and 20 in the control group. The former group received 6,000 impulses (energy flux density, 0.11 mJ/mm2) in three sessions after local anaesthesia. The control group had 6000 impulses of sham ESWT after local anaesthesia. The patients were examined at six and 12 weeks after treatment by an independent observer who evaluated the Constant score and level of pain. We found an increase in function and a reduction of pain in both groups (p < or = 0.001). Statistical analysis showed no difference between the groups for the Constant score and for pain. We therefore do not recommend ESWT for the treatment of tendinitis of supraspinatus.

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↗

PubMed2000

Spinal load changes during rotatory dynamic sitting.

OBJECTIVE: To measure load and moment changes acting on the lumbar spine during rotatory sitting. BACKGROUND: A new chair concept generating dynamic stimuli by alternating rotations in the horizontal plane of the chair's seat was recently developed. METHODS: Load and moment changes were measured telemetrically with a spinal fixator device in vivo. RESULTS: A rotatory frequency of 0.22 Hz with an amplitude of 1.8 degrees to the right and left side showed maximum axial force changes in the fixator of 23 N and maximum bending moment changes of 0.52 Nm. CONCLUSIONS: Lumbar force and moment changes during dynamic sitting occur, although only one patient was included in the study. Reasons could be temporary muscular activation in order to adapt the body's equilibrium conditions at the end-point rotation. RelevanceOur measurements suggest that a rotatory chair does have an effect on lumbar spine forces. It becomes more likely that this concept could improve the discs' nutrition and may prevent low back pain.

Adult↗

PubMed2000

Size and direction of hip joint forces associated with various positions of the acetabulum.

When total hip replacement is performed, the position of the acetabular component may affect wear and component survival time. We considered the questions: In what way does displacement of the hip joint center alter (1) the magnitude and (2) the direction of the resultant force? Biomechanical tests were carried out on a human multibody model. After displacement of the hip joint center, the resultant forces were calculated for the single leg stance. With the flexed single leg stance, maximum hip joint forces were observed with lateral, cranial, posterior displacement. The peak forces were affected by the modeling of a gluteus maximus wrapping point at the ischial tuberosity and were overestimated when this was removed. With the straight single leg stance, posterior displacement decreases the total load on the hip joint because of the increased leverage of the rectus femoris. With regard to the direction of the resultant force, medial displacement increases the angles in both planes, cranial displacement increases it in the sagittal plane (cranial, posterior-caudal, anterior), and anterior displacement decreases the angle in the sagittal plane and increases it in the frontal plane (medial, cranial-lateral, caudal). The direction of the force is relatively insensitive to displacement of the hip joint center. The results presented here indicate a marked increase in the force after lateral, cranial, posterior displacement of the center in the flexed single leg stance. To avoid extreme joint loading and to reduce the wear after total hip arthroplasty, the cranial and posterior regions of the acetabulum should be fully reconstructed. A high hip joint center has an adverse effect on the magnitude of the force, although the directions are hardly affected by it.

Acetabulum↗

PubMed2000

Lumbar spine curvature during office chair sitting.

Prolonged sitting is generally accepted as a high risk factor in low back pain and it is frequently suggested that a lordotic posture of the lumbar spine should be maintained during sitting. We asked whether the sagittal curvature of the lumbar spine during sitting is affected by the seat tilt, backrest and the direction of the synchronised mechanism of the back and seat tilt (synchro tilt). Two office chairs were tested by multibody analysis interfacing a human model with a chair model. Results indicate that a synchronised mechanism of an office chair representing a posterior tilt of the seat while the backrest is reclined maintains an evenly distributed lumbar lordosis. The segmental angles are between 3.1 and 3.6 degrees at the lumbar vertebrae 1/2-4/5 (L1/2-L4/5). These lumbar spine segmental angles are not sensitive to the backrest height. In contrast, a synchro tilt concept with a reduction of the seat's posterior tilt while the backrest is reclined causes a strong reduction of the lumbar lordosis in backrest recline with a maximum reduction from 11.7 to 2.8 degrees in L4/5. As a consequence of these results, a synchro tilt concept with a posterior tilt of the seat while the backrest is reclined is preferable from the lumbar spine kinematics point of view.

Ergonomics↗