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Biomedical subjects

M Starker

Publications and source records attributed to M Starker.

29 records · Page 2Linked to original sources
PubMedDate not supplied

[Individual cement-free total hip endoprosthesis in a patient with a rare form of dwarfism (Fuhrmann syndrome)].

We present a single case study of a 47-year-old female patient with a rare form of primary dysostotic dwarfism. This syndrome was first described by Fuhrmann in 1972. Seven years ago, this patient underwent bilateral cementless total hip arthroplasties for severe osteoarthritis about her hips. Custom-made components were used. While achondroplastic patients present with wide femoral medullary canals, it is clinically relevant that Fuhrmann Syndrome features narrow femoral medullary canals. This complicating anatomical factor in Fuhrmann syndrome as well as the increased anteversion angles were overcome by the use of CAD stems. We conclude that the custom-made stems, although in our case measuring half the size of the smallest commercially available design, have proved to be durable and able to withstand physiological loads at follow-up period of 72 months.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

[Functional results following Girdlestone arthroplasty].

AIM: Aim of the investigation was to identify prognostic factors predicting the level of postoperative function following Girdlestone ("G")-arthroplasty. METHODS: Data were derived from 87 patients, 90 hips, treated with "G"-arthroplasty at one institution between 1983 and 2000. RESULTS: Hip scores amounted to 38.7 (HHS) and 3.5 (Merle) points. The number of previously implanted total hip arthroplasties (THR) did not correlate with the functional result of "G"-arthroplasty (r = - 0.1400; p = 0.4524). On average, the duration of THR prior to "G"-arthroplasty was 44.6 months. Survival time of the latest THR and function of "G"-arthroplasty did not correlate (r = 0.0705; p = 0.7065). Patient age at primary THR, at follow-up, or at "G"-procedure did not correlate with HHS (r = - 0.0367, p = 0.8418, r = 0.1527, p = 0.4121; r = - 0.0151; p = 0.9356, respectively). Time following "G"-arthroplasty, averaging 90.6 months, did not correlate with patients function (r = 0.0920, p = 0.6289). Revision following "G"-procedure and the presence of diabetes positively correlated (p = 0.0104). The appearance of cement in the femoral canal and radiographic signs of persistent bone infection correlated significantly (p = 0.0572). CONCLUSION: Patient age, duration of "G"-hips, and number of prior THR were not reliable to predict the function of "G"-arthroplasty.

Adult↗
PubMedDate not supplied

[Assessment of implant position of CTX-custom-made stems with EBRA-FCA in 107 cases of total joint replacement].

AIM: The aim of this study was to assess the ratio of correct and malpositioned stems in a THR population with custom-made stems. Furthermore, any relation of the extent of deviation from the exact stem position and defined patient variables was evaluated. METHODS: Preoperatively, in three-dimensional virtual reality, CTX-individual hip stems were positioned in femora reconstructed from the individual patient's CT data until a stable cortical fit was achieved. Postoperative femoral stem position was measured with EBRA-FCA (EinzelBildRontgenAnalyse-Femoral Component Analysis). Differences of planned and actual depth of stem position were calculated for 107 CTX-custom-made hip stems implanted at one institution. RESULTS: Compared to preoperative planning 59 hip stems were placed too high, while 16 were placed exactly to within one millimeter and 32 were positioned too low. Deviations of postoperative stem position from preoperative planning did not correlate with previous femoral osteotomy found in one-third of femora or femoral anteversion exceeding 25 degrees as present in two-thirds of patients. CONCLUSION: In 71 % the intraoperative stem position did match the preoperative CTX-implant fitting into virtual patient femora. 29 % of implanted stems were malpositioned, i. e., deviations were greater plus or minus 5 mm to preoperative computer planning. None of the examined variables such as body mass index, previous femoral osteotomy, surgical approach, abnormal anteversion angle served as a predictive value for CTX-stem position in this cohort.

Bone Malalignment↗
PubMedDate not supplied

[Good results with a cemented titanium stem after 7-9 years].

AIM: Because of partially ver y controversial results in cemented hip stem replacements made of titanium alloy we investigated in our own patients the mid-term survival of the "Euroform"-stem. This stem is anatomically designed for cemented fixation, made of Ti (6)Al (4)V. METHOD: Within a period between 1990 and 2000 we implanted 2,141 Euroform-prostheses. The course of 103 patients which were operated between April 1990 and April 1992 was followed up. 9 patients died in the meantime and 8 could not be reached. Of the remaining 86 patients we could examine 73 patients with 79 prostheses (87 %). Investiagtion included a questionnaire and clinical and radiological examination to create the Harris-hip-score. The follow-up was 7-9 years, with an average of 94 months. RESULT: Of those 79 prostheses, revision surgery was performed for septic loosening in three cases and for aseptic loosening in two cases. Radiologically one stem was found to be loosen. This means that for aseptic loosening we had a revision rate for aseptical femoral loosening of 2.5 % after 94 months with a mean Harris-hip-score of 84 points. Good or excellent results were found in 82 %, fair results in 9 % and poor results in 9 %. CONCLUSION: The "Euroform" prosthesis is a cemented titanium alloy stem that has in contrary to some other published studies good mid- to long-term results.

Adult↗
PubMedDate not supplied

[Total femur replacement following multiple periprosthetic fractures between ipsilateral hip and knee replacement in chronic rheumatoid arthritis. Case report of 2 patients].

Periprosthetic femur fractures are one of the most severe complications in hip surgery. Osteoporosis as seen in patients with rheumatoid arthritis could favour such fractures, which are located mostly between the stems of the hip and knee prostheses. A traumatic event is not even required. The fracture rate increases with predisposing factors, such as preliminary changes of the prosthesis or osteoporosis. This paper reports two patients with rheumatoid arthritis (males, 54 and 71 years old) with femur fractures after total hip and knee replacements. Both had a severe osteoporosis caused by a long-term steroid therapy. Consecutively, both patients showed refractures of the femur with loosening of the osteosynthetic material, so that a total femur replacement was required. However, both patients are able to walk. To reduce the risk of femur fractures between the tips of knee and hip prostheses it is advisable to use knee prostheses without a proximal intramedullary stem. In this way pressure stress is reduced.

Aged↗
PubMedDate not supplied

[Studies of explanted shot-peened osteosynthesis plates].

Shot peening is a cold-working process to increase the fatigue life of osteosynthesis plates. Using ceramic particles for this process we observed no change in the corrosive properties of the plates. Up to now we implanted 37 shot peened osteosynthesis plates for fixation of intertrochanteric osteotomies. 13 plates were explanted after an average time of 14,2 months. We investigated the plates as well as the tissue surrounding the implants. Metallurgic specimens showed not so many pittings at the shot peened plates in the region of the screw hole as were seen at the polished plates after the same period of implantation. By histological investigation corrosive products or fretting particles were detected mostly in the region of the screws. Only a few metal particles were found in the region between the screw holes. Analysing the elements which were black or red-brown coloured in histological specimens by scanning electron microscopy we identified these particles as metal components. But there was a great difference in the relation of the particles found in the tissue compared to the components forming the plates alloy. This is due to the difference of distribution of the metal components at the surface of the implant in comparison with the central part of the plate. These austenitic stainless steels are protected by an enrichment of Cr in the surface layer. This could be shown in the shot peened plates as well as in the polished plates. The results of our investigations show a corrosive behaviour which is at least equal at both plates types in laboratory investigations as well as after implantations in men.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMedDate not supplied

[Methods for increasing fatigue strength of osteosynthesis plates].

For years metal implants are used for osteosynteses with good success. But there have been always fractures of implants, which need reosteosynteses in most cases. In publications an inadmissible high mechanical stress in the implants is responsible for the early failure. This stress is preponderant a reversed bending stress and leads then to fatigue fracture. In the technical practice shot peening and coining are used with success to improve the fatigue behaviour of dynamic stressed parts. It was obvious to research the effect of this treatments on the fatigue behaviour of implants too. Therefore reversed bending experiments of implants were carried out in the original state, after coining and after definite shot peening to obtain statistical calculated S-N-curves. The reversed bending amplitude without fracture of the coining implants increased 37% in opposition to original state. After shot peening this value even increased 111%.

Bone Plates↗
PubMedDate not supplied

[Validation of computerized tomography antetorsion angle measurement of the femur].

AIM OF THE STUDY: Several CT-procedures exist to determine rotational variances of the femur. However, solely on the basis of few CT-scans and without a three-dimensional reconstruction of the femur, it is impossible to define the exact course of the femoral neck axis. Looking for determination of the exact course of the femoral neck axis, auxiliary constructions need to be called upon. Aim of the study was to validate several existing CT-procedures and analyse their respective error rates. METHOD: Fourty-five femora were CT-scanned and subsequently reconstructed three-dimensionally in this study. Femoral anteversion was measured using three different CT-methods in each of these femora and in addition, the respective anatomical anteversion was determined in each femur. In order to test the reliability of such methods, flexion of the femora around the center of the femoral head as well as a varus deformity of the longitudinal axis of the femora were simulated and anteversion measurements were repeated in such simulated positions. Results were statistically analysed using SPSS. RESULT: All tested CT-methods, when compared to the anatomical anteversion of a femur, showed differing anteversion-angles with statistical significance (p < 0.001). Equally, the results of the individual methods tested differed with significance. Due to a high correlation with the anatomical anteversion, all methods examined expressed trend of anteversion. Under simulated hip flexion, the "Ulmer Method" produced different values with statistical significance which were, however, without correlation to anteversion values in joint extension. With statistical significance, the "Essener Method" produced different anteversion values when the longitudinal axis of the femur was modified; however, these values highly correlated to anteversion values of femora with unchanged longitudinal axis. CONCLUSION: Our results lead us to conclude that the "Essener Method" being an interindividual method and independent from positioning, is the most suitable procedure as it allows for the correction of errors with respect to anatomical anteversion.

Femur↗
PubMedDate not supplied

[Artificial hip joint implantation in stiff-man syndrome].

UNLABELLED: AIM AND METHOD OF THE STUDY: The Stiff-Man syndrome is characterized by progressive, usually symmetric rigidity of the axial muscles of the trunk with superimposed painful spasms precipitated by various stimuli. The neurologic disorder of SMS is discussed with respect to its symptoms of orthopedic interest including treatment modalities for total hip replacement. RESULTS: An increased incidence of hip disease in patients with SMS seems unlikely according to our analysis. CONCLUSION: SMS-patients should, however, be defined at risk for heterotopic bone formation following hip arthroplasty requiring a perioperative prophylaxis.

Adult↗