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Biomedical subjects

H Kaufer

Publications and source records attributed to H Kaufer.

At least 19 recordsLinked to original sources
PubMed1996

Shape and size of virgin ultrahigh molecular weight GUR 4150 HP polyethylene powder.

Sizes and shapes of micron- and submicron-sized structures in four lots of virgin GUR 4150 HP ultrahigh molecular weight polyethylene powder were determined by using low-voltage scanning electron microscopy and image analysis. One thousand two hundred micron-sized virgin powder particles and 1200 of their constituent submicron-sized structures were analyzed. The mean maximum diameter of the micron-sized particles was 81.3 microns, and that of the submicron-sized particles was 0.82 micron. Particle shapes, as determined by the aspect ratio (maximum diameter divided by minimum diameter), were remarkably consistent from lot to lot and between micron- and submicron-sized particles (1.55 versus 1.53, respectively). Significant lot to lot variability was observed in the sizes of the micron-sized particles, and the size distribution of the submicron-sized particles closely follows the size distribution of the submicron-sized particles observed in tissue retrievals. This variability leads to questions about variability in polyethylene quality and in vivo wear performance. Size similarity between the submicron-sized particles retrieved from tissues and that observed in virgin powder supports the hypothesis that polyethylene debris has two origins: particles released from structures retained from the virgin powder, and particles generated de novo by friction and wear.

Biocompatible Materials↗
PubMed1995

Low-voltage scanning electron microscopic imaging of ultrahigh-molecular-weight polyethylene.

Submicron ultrahigh-molecular-weight polyethylene (UHMWPE) wear particles from total joint prostheses may contribute to implant failure through particle-mediated aseptic loosening. The purpose of this study was to examine the microstructure of virgin UHMWPE powder to determine its morphology for future comparison with wear debris. A new method of low-voltage scanning electron microscopy (LVSEM) in an oil-free vacuum was applied, which produced high-resolution images of UHMWPE micromorphology, while minimizing specimen damage and obviating the need for image processing. GUR 415 UHMWPE virgin powder particles were examined by using routine high-voltage SEM, LVSEM, and image analyses. LVSEM showed that UHMWPE particles were composed of submicron-size spherical subparticles connected by numerous nanometer-size fibrils. These spherical subparticles had a highly textured surface morphology seen only by LVSEM. Fracture of the nanometer-size fibrils was observed. Routine high-voltage SEM obfuscates the intricate and delicate UHMWPE micromorphology as well as the damage done by the accompanying high-voltage electrons. This study suggests that the micromorphology of wear particles previously studied with routine high-voltage SEM was overlooked or damaged, justifies the need for LVSEM in future studies, and raises the question of what is the true morphology of polyethylene wear debris retrieved from human tissues.

Biocompatible Materials↗
PubMed1993

Two-year follow up of bipolar hemiarthroplasty.

Forty-seven bipolar hemiarthroplasties were performed from January 1985 to December 1986. Twenty-three patients (24 hips) returned for a history, physical, and repeat radiographs. Ten primary press-fit and two cemented primary bipolar hemiarthroplasties were performed. Four patients underwent cemented and eight received press-fit revision bipolar hemiarthroplasties. Fourteen patients had simultaneous cancellous, reamed femoral head autograft, or allograft acetabular bone augmentation. Omitting one patient who had replacement for Lévi's pleonosteosis, the average acetabular migration among the remaining 23 patients was 4 mm of superior and 1.5 mm of medial progression. The mean modified d'Aubigne hip score was 33 for primary press-fit arthroplasty, 30 for primary cemented arthroplasty, 22 for press-fit revisions, and 32 for cemented bipolar revision arthroplasty. Morcellized bone graft tended to variably resorb with time. Among the press-fit stems, all but two patients complained of at least occasional thigh pain. All but one patient with primary press-fit hemiarthroplasty walked with a limp. We conclude that, although good early results can be obtained, significant number of patients will have groin and thigh pain. We have found no evidence either radiologically or clinically that nonstructural bone grafting with reamed femoral head will reliably incorporate or prevent further acetabular migration.

Acetabulum↗
PubMed1991

Arthrodesis of the knee with an intramedullary nail.

The cases of twenty patients who had an arthrodesis in which an intramedullary nail was used for stabilization were reviewed at an average follow-up of six years. The predominant indications were infection after total knee arthroplasty and post-traumatic pain and instability. Other indications included aseptic loosening of the components of a total knee arthroplasty, reconstruction after resection of a giant-cell tumor, non-union of a fracture of the distal part of the femur or the proximal part of the tibia, and failed external-compression arthrodesis. Success was achieved in seventeen patients (85 per cent), and functional stability immediately postoperatively was gained in all twenty. Of the three patients in whom the arthrodesis failed, all had sustained an intraoperative fracture, and infection eventually developed. Of the twelve nails that were secured to the greater trochanter with a loop of stainless-steel wire, none showed evidence of proximal migration. Of the eight nails that were not thus secured, two migrated proximally, necessitating removal of the nail. Two drawbacks to this operation are the long duration and the large amount of blood that is lost. The major advantage is that a high percentage of patients have progression to a stable fusion despite serious problems. Furthermore, all but seven patients (including the six who had a tumor or who had sustained an intraoperative fracture) were able to bear full weight by the second postoperative week. Only a few patients needed an external support for walking.

Adult↗
PubMed1990

Traction force profiles associated with the use of a fracture table: a preliminary report.

A load cell was developed that can reliably monitor longitudinal traction forces applied to limbs during several different orthopaedic procedures. This permitted determination of tensile loads and the effects of patient limb positions on tension magnitudes. The relationships between the magnitude and duration of applied tension to functional nerve changes were also studied. This preliminary report reviews traction force data on seven patients for eight operations. Mean peak loads for femoral, tibial, and hip procedures were 686, 356, and 306 N, respectively. Adduction of the limb around a fixed peroneal post caused great increases in traction forces.

Adult↗
PubMed1990

Treatment of juxtaarticular nonunion fractures at the knee with long-stem total knee arthroplasty.

A retrospective study of ten patients with juxtaarticular nonunions at the knee treated with long stem total knee arthroplasty was performed. The average age of the patients was 76 years old, with an average follow-up of 36 months. The nonunions were present for an average of 36 months. There were six patients in the series with prior total knee arthroplasty. Clinical union was achieved in all ten patients. All patients improved their ambulatory status. Range of motion improved from an average preoperative range of 40 degrees to an average postoperative range of 85 degrees. Complications occurred in three of ten patients, with one being a postoperative infection. Surgical techniques are described to aid in treatment of difficult juxtaarticular nonunion fragments.

Aged↗
PubMed1990

Pyarthrosis of the knee. Treatment considerations.

Patients with pyarthrosis of the knee can be effectively managed by several different methods. A retrospective review of patients with the diagnosis of septic arthritis of the knee was undertaken to determine the efficacy of two different treatment programs. Multiple-needle arthrocentesis was contrasted with formal arthrotomy drainage. In this series, patients with a longer than three-day history of a knee pyarthrosis and those with Staphylococcus aureus or enteric gram-negative organisms on culture benefited from open drainage procedures in lieu of repeated aspiration techniques.

Adolescent↗
PubMed1989

Partial pelvic resection as an alternative to hindquarter amputation for skeletal neoplasms.

Selected neoplasms of the bony pelvis can be effectively treated by partial pelvic resection, rather than by traditional hemipelvectomy. Eleven patients with skeletal neoplasms were managed by partial pelvic resections with limb sparing. These cases demonstrate that good postresection results can be achieved without reconstructive joint procedures.

Activities of Daily Living↗
PubMed1988

Septic polyarthritis and its relation to systemic disease processes. A report of three cases.

In the case of a postoperative joint infection, the orthopaedic surgeon is frequently blamed. Certain intrinsic disease processes, however, make a joint more susceptible to infection. In these three reports of septic polyarthritis, all patients had underlying systemic disorders, including rheumatoid arthritis, diabetes mellitus, and hemophilia A. Two of the three patients had had no recent surgical procedures. This suggests that the development of a pyarthrosis may depend at least as much on the patient's underlying systemic condition as on the surgeon and his or her technique.

Adult↗
PubMed1988

Proximal tibial osteotomy. Factors that influence the duration of satisfactory function.

Survival analysis studies of 40 patients treated with high tibial osteotomy for arthritis with angular deformity were performed to determine the dominant factors that adversely affected long-term knee function. Obesity, advanced age, and postoperative overcorrection or undercorrection resulted in short durations of successful function. On the average, the probabilities for continued useful function of the knee at tested intervals were: one year, 86%; three years, 64%; five years, 50%; and nine years, 28%.

Adult↗
PubMed1987

Fibrous dysplasia. An analysis of options for treatment.

The results of treatment of sixty-five symptomatic lesions in forty-three patients who had fibrous dysplasia were reviewed. For fourteen (93 per cent) of the fifteen times that a lesion in the upper extremity was treated non-operatively, the result was satisfactory. These results were independent of the patient's age when first seen. In contrast, in the lower extremity, the results were highly dependent on the age of the patients at the time of the initial presentation of symptoms. In patients who were eighteen years old or older, eight (88 per cent) of the nine times that a lesion involving the lower extremity had closed treatment and both times that a lesion was treated with curettage and bone-grafting, the result was satisfactory. The results of these modalities of treatment in patients who were less than eighteen years old were discouraging. Twenty-eight (88 per cent) of the thirty-two times that closed treatment was used and twenty-five (81 per cent) of the thirty-one times that curettage and bone-grafting was used, the result was unsatisfactory. However, after eighteen (86 per cent) of the twenty-one times that a lesion in the lower extremity was treated by internal fixation in a patient who was less than eighteen years old, there was a satisfactory outcome. We concluded that closed treatment of a symptomatic lesion in the upper extremity generally provides satisfactory results. In patients who are less than eighteen years old, neither closed treatment nor curettage and bone-grafting is adequate treatment for a symptomatic lesion in the lower extremity. Internal fixation should be strongly considered in these young patients.

Adolescent↗
PubMed1987

Resection arthroplasty as a salvage procedure for a knee with infection after a total arthroplasty.

Between 1970 and 1983, resection arthroplasty was done as a salvage procedure for twenty-eight knees (twenty-six patients) with infection after total arthroplasty. Eleven patients had multiarticular rheumatoid arthritis; fourteen, osteoarthritis; and one, multiarticular neuropathic arthropathy. Systemic signs of infection were eliminated in all patients and local signs, in 89 per cent of the patients. After resection arthroplasty alone, fifteen patients were able to walk independently. Six patients with monoarticular osteoarthritis who found the resection arthroplasty to be unacceptable had a successful secondary arthrodesis. In three patients a spontaneous bone fusion developed after the resection, with the knee in a good position. Two patients who were unable to walk before the resection arthroplasty were still unable to do so postoperatively. Neither the patient's disease nor the type of prosthesis that had been used was a reliable predictor of success of the resection arthroplasty. The patients who had had the most severe disability before the total knee arthroplasty were most likely to be satisfied. Patients who had had less disability were more likely to find the results of resection arthroplasty to be unsatisfactory.

Adult↗
PubMed1986

Discordance for ankylosing spondylitis in a B27 negative monozygotic twin.

A case in which only one sibling of an identical, HLA-B27 negative, twin pairing is affected by ankylosing spondylitis is reported. While endogenous variables may predispose certain populations to ankylosing spondylitis, the discordance illustrated in these seronegative monozygotic twins indicates that exogenous factors may certainly influence the development and course of this disease.

Aged↗
PubMed1986

Spherocentric arthroplasty of the knee. A long-term and final follow-up evaluation.

The spherocentric knee was designed as an intrinsically stable prosthesis to manage the problems of deformity, instability, and metaphyseal bone loss in joints too severely involved to use resurfacing arthroplasty. Follow-up information has been obtained on 58 of the first 82 knees requiring spherocentric arthroplasty. After an average eight-year followup period, the results are gratifying with respect to pain, ambulatory ability, deformity, and instability. The infection and reoperation rates of 5% and 15% seem satisfactory when one considers the severely disabled patient and pathologic conditions of the knee joint.

Evaluation Studies as Topic↗
PubMed1986

Resection arthroplasty: an alternative to arthrodesis for salvage of the infected total knee arthroplasty.

Arthrodesis remains the procedure of choice for salvage of an infected total knee arthroplasty in patients with relatively minor preprosthetic arthroplasty disability. Patients with very severe preprosthetic disability resulting from multiarticular disease or other systemic disease may be treated best by a resection arthroplasty. Systemic sepsis can be eliminated in almost all patients, and drainage can be eliminated in most. Those patients who find the stability of a resection arthroplasty inadequate for their needs can have a secondary arthrodesis performed with an intramedullary rod, which yields a high probability of success. External immobilization is not necessary. The advantages of a two-stage arthrodesis are that it is an elective procedure, performed in a limb free of sepsis. The patient has been psychologically prepared for the arthrodesis, and the two-stage procedure has a high probability of success. Neither the underlying diagnosis, nor the infecting organism, nor the type of infected prosthesis is a reliable predictor of success or failure of either a resection arthroplasty or a second-stage arthrodesis.

Aged↗
PubMed1985

Split posterior tibial-tendon transfers in children with cerebral spastic paralysis and equinovarus deformity.

In the treatment of equinovarus deformity of the foot in children with cerebral spastic paralysis, to supplement heel-cord lengthening, we split the posterior tibial tendon and transferred its posterior half laterally into the peroneus brevis tendon. Thirty-seven operations were performed on thirty-one hemiplegic, quadriplegic, and diplegic children who were followed for a mean of eight years postoperatively (range, four to fourteen years), at which time twenty-six of the thirty-one children were skeletally mature. There were thirty excellent, four good, and three poor results. The results did not deteriorate with time. Thirty-two of thirty-four children with good or excellent results had functioning dorsiflexors of the foot and were brace-free postoperatively. The children who had a poor result had recurrent deformity, but none had development of a calcaneal or calcaneovalgus deformity.

Adolescent↗