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Biomedical subjects

E W Fritsch

Publications and source records attributed to E W Fritsch.

8 recordsLinked to original sources
PubMed2006

[Cervical disc prostheses].

Endoprosthetic replacement for spinal cord disorders represents an attractive alternative to fusion in those cases where surgery appears necessary for degenerative disc disease. At least in theory it has been proven that placement of an endoprosthesis minimizes undue stress on the adjoining segments and its possible negative consequences. Furthermore, cervical endoprostheses facilitate speedier rehabilitation and the problems involved in removal of the bone chip become irrelevant. Clinical results reported to date for the cervical spine are very encouraging and indicate that endoprosthetic replacement has been quite successful particularly for difficulties in multilevel approaches. However, long-term results for cervical endoprostheses have not yet been published and therefore at present there are no reference values for the viability of the prosthesis with regard to the aseptic loosening rate. There are also no findings available on how the implanted cervical prosthesis will behave when bone quality diminishes at an advanced age.

Biomechanical Phenomena↗
PubMed1997

Fixation strength of a biodegradable interference screw and a press-fit technique in anterior cruciate ligament reconstruction with a BPTB graft.

The objective of this study was to evaluate the fixation strength of a biodegradable interference screw (Arthrex, Naples, FL) compared with press fit fixation and a titanium interference screw in anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) graft. Porcine lower limbs were used. Ultimate failure loads of the biodegradable screw (805.2 N; range 680 to 995 N) did not differ significantly from ultimate failure loads of titanium interference screws (768.6 N; range 544 to 1094 N). Press fit fixation provided significant (P < .01) lower fixation strength (462.5 N; range 80 to 825 N). These results support the conclusion that biodegradable interference screws are a reasonable alternative in terms of primary fixation strength.

Animals↗
PubMed1996

The failed back surgery syndrome: reasons, intraoperative findings, and long-term results: a report of 182 operative treatments.

STUDY DESIGN: A retrospective study was performed of 182 revisions on failed back surgery syndrome from the years 1965 to 1990. OBJECTIVE: To analyze the reasons for failure of primary discectomy, the outcome of the revisions, and factors that influenced those outcomes. SUMMARY OF BACKGROUND DATA: The reported reintervention rates after lumbar discectomy range from 5% to 33% depending on the type of surgical procedure. The authors' former investigations reported a revision rate of 10.8% in evaluating 1500 lumbar discectomies. METHODS: Because the documentation was standardized, detailed data of all patients were available. To gain further information concerning the long-term results a questionnaire was used. Computer processing and statistical tests were performed. RESULTS: One hundred eighty-two revisions were performed on 136 patients. Forty-four patients (34%) were revised multiple times. Generally, recurrent or uninfluenced sciatic pain and neurologic deficiency or lumbar instability led to reintervention. Recurrent lumbar disc herniation mainly was found at the first reintervention. In multiple revision patients the rate of epidural fibrosis and instability increased to greater than 60%. In 80% of the patients the results were satisfactory in short-term evaluation, decreasing to 22% in long-term follow up (2-27 years). CONCLUSIONS: Laminectomy performed in primary surgery could be detected as the only factor leading to a higher rate of revisions. A trend toward poor results after recurrent disc surgery seems to be fateful because of the development of epidural fibrosis and instability. In severe discotomy syndrome, a spinal fusion seems to be more successful than multiple fibrinolyses.

Back↗
PubMed1996

Static and fatigue properties of two new low-viscosity PMMA bone cements improved by vacuum mixing.

With the objectives of reducing toxicity and improving the mechanical properties of the prior Sulfix-6 cement, a new low-viscosity bone cement with a new catalyst (Sulfix-60), and a gentamycin containing cement (Allofix-G) were developed. Although static strength could be improved in comparison with the older Sulfix-6 cement, investigations regarding improved fatigue strength and the influence of vacuum mixing on the mechanical properties were missing. Dynamic weakness was the major disadvantage of the older Sulfix-6 cement. To investigate fatigue strength specimens of the new bone cements were tested with load guiding until breakage or 20 million cycles. In the three series, hand mixing, vacuum mixing, and vacuum mixing with additional pressurization were performed, respectively. Vacuum mixing led to increased fatigue stability from 6.3 to 9.1 MPa for Sulfix-60, and from 6.3 to 8.2 MPa for Allofix-G. Additional compression had no significant effect. A 200% increased fatigue strength was detectable in comparison with the older cement. In the four-point bending test, similar results were found. It could be proved that an increased polymerization rate achieved with the use of the new catalyst was responsible for the improved mechanical properties of the new bone cement Sulfix-60.

Bone Cements↗
PubMed1996

Radiographic course after acetabuloplasty and femoral osteotomy in hip dysplasia.

The radiographic course of 101 hips with residual dysplasia treated with roof plasty combined with intertrochanteric varus derotation osteotomy using the osteotomy wedge as a roof graft after Mittelmeier were reviewed. The average followup period was 8.8 years. The acetabular angle was improved by an average of 16 degrees (postoperative mean, 19 degrees; average at followup, 18 degrees). The center edge angle also was improved by 16 degrees and was stable at 25 degrees average at followup. The neck shaft angle, abnormal in 70% of hips preoperatively, was reduced by the varus osteotomies to a mean of 111 degrees and showed a spontaneous postoperative increase to normal values of an average of 129 degrees. There was no correlation of the postoperative of the neck shaft angle to patient age, preoperative valgus extension, correction angle, or length of followup. In nearly all cases, an almost anatomic joint shape was achieved. With a complication rate of only 1%, especially regarding the rate of necroses of the femoral head, the presented surgical technique can be recommended as highly effective, reliable, and safe for the treatment of congenital hip dislocation.

Acetabulum↗
PubMed1996

Ceramic femoral head fractures in total hip arthroplasty.

A failure analysis was performed of 4341 alumina ceramic heads articulating with 2693 alumina ceramic and 1464 polymer sockets implanted over 20 years (1974 to 1994). From 1974 to 1982, a mushroom shaped head with ceramic neck was used in 1069 cases, and from 1982 to 1994 a ball type head was used in 3272 cases. In the ceramic/ceramic cases, the average followup was 11 years, and in the polymer pairing cases, the average followup was 6 years. In ceramic self pairing with the mushroom shaped head, the fracture rate was 0.4% (5 of 1069). With the ball type head, the fracture rate was 0.06% (1 of 1763). In articulation with polymer sockets, only 1 head fracture occurred (0.07%). In the group of cases with ceramic/ceramic pairing, the reason for fracture was direct trauma in 4 cases, recurrent neck impingement in 2 cases, and fatigue failure in 1 case. The only case with ceramic head fracture in polymer pairing also was caused by direct trauma. Fractures of the alumina ceramic heads cannot be avoided, but the use of ball type neckless heads brought the fracture rate close to 0. Under the aspect of material safety, it seems to be possible to use the great advantage of the superior low wear of the alumina/alumina couple with negligible fracture risk.

Ceramics↗