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Biomedical subjects

J Steen Jensen

Publications and source records attributed to J Steen Jensen.

14 recordsLinked to original sources
PubMed2006

Quality of polypropylene sockets for trans-tibial prostheses in low-income countries.

Based on six series of patients (n = 198) participating in clinical field testing of prosthetic feet and all provided with trans-tibial prostheses in accordance with the polypropylene component and assembly system developed by the International Committee of the Red Cross (ICRC) follow-up studies by teams consisting of an orthopaedic surgeon and a Category-I prosthetist-orthotist were conducted. A series of quality measures were tested against previously published quality benchmarks. The polypropylene system gives a consistent product and allows for increased demands on quality benchmarks. The acceptance of discomfort and pain could be reduced to 5 +/- 5%. The technical performance demands were reduced for misalignment to 10 +/- 5%. In general for all quality measures the range could be reduced to +/- 5%. These new demands reflect what an orthopaedic workshop outside of a teaching system should be able to attain.

Adolescent↗
PubMed2006

Clinical field testing of polyurethane feet for trans-tibial amputees in tropical low-income countries.

In a prospective controlled study, 172 polyurethane feet of different designs were fitted to 155 amputees with trans-tibial prostheses. These were followed in respect of their durability. The amputee compliance was in general good, and 87% were satisfied with their device. After 18 months the failure rate of 20% with the CIREC spring-blade foot was significantly better than the others, but poorer craftsmanship, higher complaint rate and lower compliance rate cast some doubt on the results. The results with the conventional SACH foot constructions with polyurethane as filling and covering materials were so poor after 18 months that their use cannot be recommended in tropical areas of the developing world.

Adolescent↗
PubMed2006

Clinical field testing of vulcanized rubber feet for trans-tibial amputees in tropical low-income countries.

In a prospective, controlled study, 186 prosthetic rubber feet of different designs were fitted to amputees with trans-tibial prostheses. There were 158 amputees available for follow-up. The amputee compliance was good and 89% were satisfied with their device. After 18 months of use one VI-Solid rubber foot from VVAF in Cambodia had failed, as compared to 11% failures with the same foot with a heel cavity, 3% with the EB-1 sandwich construction from POF in Vietnam, all performing significantly better than the 62% encountered with the vulcanized rubber foot from ICRC in Cambodia; the latter representing half of the feet failing in amputees walking bare-footed. Nearly all failures were located at the foot-sole or the keel. The failure rate was 20% for the HI-Cambodia foot after 12 months. After 24 months of use, still only one VI-Solid rubber foot had failed and this foot design was found superior to the others in regard of durability.

Adolescent↗
PubMed2006

Clinical field testing of vulcanized Jaipur rubber feet for trans-tibial amputees in low-income countries.

The purpose of this study was to check out the performance and durability of vulcanized Jaipur rubber feet in tropical areas of the developing world. Forty-one MUKTI and 40 NISHA feet were followed for 16 (8 - 17) months. The user compliance was high and nearly all were satisfied. Failure of the prosthetic foot with the need for exchange at the end of the study amounted to 27% (22/81), which is equivalent to a mixed series of rubber feet previously reported (Jensen et al. 2006b). Failures were mostly related to skin fracture and gliding between sponge rubber layers of the heel block.

Adult↗
PubMed2005

Sand-casting technique for trans-tibial prostheses.

A sand-casting technique for trans-tibial sockets was applied to 28 amputees, and the prosthetic fit observed through transparent check sockets. The results were better than historical reports of fittings with plaster of Paris casting by qualified prosthetists. The fit was consistently and evenly larger than the stump, but total contact could be achieved by applying three (two to five) stump socks. This would normally be considered on the high side of a good fit.

Adult↗
PubMed2005

Quality benchmark for trans-tibial prostheses in low-income countries.

Based on four series of patients (N=141) participating in clinical field testing of prosthetic feet and all provided with trans-tibial prostheses in accordance with the polypropylene component and assembly system developed by the International Committee of the Red Cross (ICRC) a series of quality benchmarks was developed and tested against historical data. The patient compliance demands were set for walking >1 km at 90 +/- 10%, non-users at 5 +/- 5%, discomfort at 10 +/- 10%, pain at 10 +/- 10%, and patient satisfaction at 90 +/- 10%. The technical performance demands were set for good socket fit at 60 +/- 10%, misalignment at 15 +/- 10%, insufficient craftsmanship at 10 +/- 10%, and requirements for socket change at 10 +/- 10%.

Adolescent↗
PubMed2003

Clinical field-testing of ATLAS prosthetic system for trans-femoral amputees.

The ATLAS prosthetic system was tested on 47 trans-femoral amputees in two tropical areas. Although the craftsmanship was not acceptable, 46% (16/35) were malaligned many with the foot dorsiflexed, the user compliance was good (91%, 32/35), and the satisfaction rate high (71%, 25/35). However, after 7-10 months failures occurred in 83% (29/35) mostly because of problems with the ATLAS knee mechanism. A modification was tested and 80% (12/15) had again failed at the knee after 6 (2-12) months. The ATLAS system in its current design should be abandoned for use for trans-femoral amputees.

Adolescent↗
PubMed1993

Mechanical failure of hydroxyapatite-coated titanium and cobalt-chromium-molybdenum alloy implants. An animal study.

Defects in the hydroxyapatite (HA) ceramic coatings applied to metallic implant systems may occur at the time of insertion or at the time of in vivo loading. However, defects may also occur with time because of interaction with physiological fluids. A canine study was performed to make a histological and biomechanical evaluation of HA-coated titanium and cobalt-chromium-molybdenum alloy implants in a non-weight-bearing model. Twelve cylindrical plugs were inserted into the medial femoral condyle on 6 mongrel dogs. HA-coatings of 80-120 microns thickness were applied to 6 Cr-Co-Mo implants and 6 Ti-6AI-4V implants. The implants were removed together with adjacent bone tissue after 4 weeks. There were no statistically significant differences between the two groups for interface shear strength. No differences were encountered with HA-coating on Cr-Co-Mo or on Ti-6AI-4V, failure consistently being caused by disruption between the metal surface and the HA-coating, which remained fixed to the bone. At histologic evaluation the HA-coated implants exhibited a great amount of direct bone-to-implant contact. In spite of that, this study indicates that HA-coating on smooth metal surfaces might not be suitable for clinical use, because of low bonding strength between metal and coating.

Alloys↗
PubMed1992

Additional mechanical tests of bone cements.

A revision of the ISO-standard for bone cement testing has been proposed to include compressive strength after 24 hours in air and 4-point bending testing after 50 hours in a 37 degrees water bath. Nine commercially available bone cements were tested in accordance with the new program. Compressive strength varied from 78 to 100 MPa, bending strength from 48 to 74 MPa and bending modulus from 2.2 to 2.8 GPa. The highest strengths, but also the highest stiffness, were encountered with Simplex brands and low-viscosity cements.

Acrylic Resins↗
PubMed1986

Hemi-arthroplasty of the hip followed by ipsilateral fracture of the femoral shaft.

In a series of 74 ipsilateral fractures of the femoral shaft in relation to hemi-arthroplasties, treatment by a cemented long-stem total hip replacement was found to be superior to conservative treatment or internal fixation without removal of the prosthesis. Acceptable clinical results were obtained in 89 per cent of these cases.

Aged↗
PubMed1983

The healing of through-knee amputations in relation to skin perfusion pressure.

The healing in 20 through-knee amputations was compared with preoperatively measured skin perfusion pressure, determined as the minimal external pressure required to stop the washout of isotopes injected intradermally 10 cm distal to the knee joint. Out of 18 amputations with a skin perfusion pressure of above 20 mmHg only 2 failed to heal, whereas 2 out of 4 cases with skin perfusion pressure below 20 mmHg failed to heal. It is concluded that the through-knee amputation must be considered in cases where the circulation is borderline for healing in below-knee amputation.

Aged↗
PubMed1983

Life expectancy and social consequences of through-knee amputations.

Amputation surgery for gangrene of the lower limb has two primary goals, to save life and to bring the patients back to their previous living conditions. If this can be achieved with restored walking ability the result of the treatment is considered a full success. The purpose of this paper is to describe the risk of death and possibility of returning through-knee amputees to their own home, relating the results to other major levels of amputation of the lower limb.

Adult↗