Biomedical subjects

H C Amstutz

Publications and source records attributed to H C Amstutz.

At least 19 recordsLinked to original sources

PubMed1992

Acetabular reconstruction with a threaded prosthesis for failed total hip arthroplasty.

The MEC-Ring threaded acetabular component was used in 35 patients for revision of failed cemented hip arthroplasties, and 32 have been observed for two to four years (mean, 2.5 years). With only a short-term follow-up period, 44% of patients have already required revision for failure of the MEC-Ring acetabular component. Patients with especially poor acetabular bone stock that had had structural bone graft had a significantly higher rate of failure. The authors developed a technique of supine oblique roentgenograms that allowed better visualization of the component-bone interface. Eighty-six percent of patients had radiolucencies, and 67% of these were progressive. The presence of progressive radiolucencies, component migration, or both was associated with a higher failure rate. Progressive radiolucencies were also associated with a worse pain score in patients whose arthroplasties have not failed. The MEC-Ring threaded component is not recommended for revision hip arthroplasty, especially in cases with poor acetabular bone stock.

Acetabulum↗

PubMed1992

A comparison of total hip arthroplasty and hemiarthroplasty for treatment of acute fracture of the femoral neck.

One hundred sixty-six acute, nonpathologic displaced femoral neck fractures in elderly patients were treated with either unipolar hemiarthroplasty (122 operations; 77 cemented, 45 uncemented) or total hip arthroplasty (THA) (44 operations; all cemented). The average age, (75.2 years of age in the THA group 76.2 years of age in the hemiarthroplasty group), anesthesia risk classification, in-hospital mortality, early complications, and dislocation rates were comparable in each treatment group. In an average long-term follow-up period of 56 months, pain, walking, and function scores were higher with THA than with cemented or uncemented hemiarthroplasty. Revision rates were 2.2% after THA, versus 7.9% for cemented hemiarthroplasty and 13% for uncemented hemiarthroplasty. Hemiarthroplasty is recommended for the older patient, who may be occasionally active outside of the household. The healthy, active patient, however, may benefit from THA rather than hemiarthroplasty.

Acute Disease↗

PubMed1992

Mechanism and clinical significance of wear debris-induced osteolysis.

Loosening of joint replacement components is often multifactorial. The quality of initial fixation is very important to the outcome of the arthroplasty and is often a factor in short-term and long-term failure. This paper discusses another important factor of implant loosening, namely wear debris induced osteolysis. Macrophages activated by the phagocytosis of particulate wear debris are the key cells in this process, which can potentially occur in any implant system regardless of implant design or fixation mode. This is because each implant system creates wear debris from the articulating surfaces and the interfaces. The clinical consequences of wear debris cover a broad spectrum from radiolucencies to massive osteolysis and implant failure. For this reason, the reduction of wear debris should be a primary goal of orthopedic research in the future.

Bone and Bones↗

PubMed1992

Etiology of deep sepsis in total hip arthroplasty. The significance of hematogenous and recurrent infections.

Between January 1970 and August 1986, 3051 total hip arthroplasties (THAs) were performed at the authors' institution. Forty-seven hips in 43 patients developed deep infection. Using clinical and laboratory criteria, patients were classified into four modes of infection: (1) surgical contamination, which included hips (N = 13) with a suspicious clinical course (e.g., persistent elevation of sedimentation rate, early radiographic signs of loosening) without another identifiable source; (2) hematogenous spread, which included septic hips (N = 19) with a temporally related infectious source and an organism consistent with that source; (3) recurrent sepsis, septic failure in a previously infected hip (N = 13); and finally, (4) infection from direct or contiguous spread, which occurred in an additional two patients. Thus the majority of infections were nonsurgical. Patients with surgically acquired infections tended to present earlier, were less likely to require a Girdlestone procedure for salvage, and were more likely to be reimplanted (p = 0.024). The incidence of surgical infections decreased with the use of improved antiseptic techniques. The incidence of hematogenous infection, however, increased during the time that a cohort was followed. Additionally, in a previously septic hip, septic failure may occur as late as seven years after THA.

Bacteria↗

PubMed1991

Incidence of deep sepsis in total hip arthroplasty. Survivorship analysis over 17 years from one hospital.

Of 3,051 total hip arthroplasties (THA) performed between January 1970 and August 1986, 47 hips in 43 patients developed deep periprosthetic infection. This population was divided temporally into three groups based on changes in our perioperative antiseptic technique. Using survivorship analysis, a significant decrease in the sepsis rate in primary THA was seen in the period since 1974 (P less than .03). Comparing all surgeries in the most recent cohort (1980-1986) to others by a Cox Proportional Hazards model (which accounts for differences in follow-up results), indicates that the relative risk of sepsis has decreased by half in this latest group. Contemporary perioperative antiseptic techniques have lowered the risk of infection in THA. Further significant decreases in sepsis incidence will likely require a reduction in the incidence of infection acquired outside the operating room.

Anti-Infective Agents, Local↗

PubMed1991

Periprosthetic chronic inflammation characterized through the measurement of superoxide anion production by synovial-derived macrophages.

Periprosthetic macrophages were isolated from the synovium of primary and revision arthroplasty patients. Inflammatory activity was determined by the level of superoxide (O2-) production de novo and in response to phorbol myristate acetate (PMA) stimulation. Nonstimulated primary arthroplasty-derived macrophages produced 2.54 +/- 2.04 pmoles of O2-/minute/10(5) cells. When identical reaction tubes were stimulated with PMA, O2- levels increased to 5.76 +/- 3.77 pmol of O2-/minute/10(5) cells. Nonstimulated revision arthroplasty-derived macrophages produced 3.26 +/- 2.02 pmol of O2-/minute/10(5) cells during this ten-minute time period. When identical reaction tubes were stimulated with PMA, O2- levels increased to 3.98 +/- 2.52 pmol of O2-/minute/10(5) cells. The difference in the ratio of O2- production in response to stimulation between primary and revision groups was statistically significant. The observation of a chronic moderate level of activation and the lack of responsiveness to a potent stimulator suggests that macrophage inflammatory activity is down-regulated in periprosthetic synovium.

Adult↗

PubMed1991

Patient activity, sports participation, and impact loading on the durability of cemented total hip replacements.

Patients with either cemented surface replacements or cemented stemmed hip prostheses and who regularly participate in sporting activities or heavy labor after total joint arthroplasty are at twice the long-term risk of requiring revision surgery for loosening as patients who are less active. For patients with surface replacement total hip arthroplasty (THA), the adverse effects of activity are greatest in patients with preoperative diagnoses other than osteoarthritis, and were seen by the sixth year postsurgery. For patients with conventional stemmed prostheses, the effects of patient activity are not seen until about ten years postsurgery. For resurfacing THA for osteoarthritis, the long-term of loosening is primarily in patients who participate in high impact activities.

Bone Cements↗

PubMed1991

Nerve palsy associated with total hip replacement. Risk factors and prognosis.

We reviewed the results of 3126 consecutive total hip replacements and identified postoperative neuropathy in the ipsilateral lower extremity after fifty-three (1.7 per cent) over-all and after 1.3 per cent of the primary arthroplasties. The prevalence was 5.2 per cent after the primary arthroplasties that had been done for congenital dislocation or dysplasia of the hip and 3.2 per cent after the revisions (all diagnoses). Thus, these two types of operations were risk factors (p less than 0.01). Limb-lengthening only partially accounted for the increased prevalence of neuropathy after these procedures. The sciatic nerve was involved in all but five extremities. The cause of the palsy was unclear or unknown in thirty (57 per cent) of the extremities. When the patients were last seen, at a minimum of one year and a maximum of sixteen and one-half years after the operation, seven extremities were normal neurologically, thirty-three had a mild neurological deficit, and thirteen had a major deficit. All patients who had complete recovery of neurological function had it by twenty-one months. Of thirty-six extremities that were evaluated at a minimum of twenty-four months after the operation, seven were neurologically normal, twenty-three had a mild persistent deficit, and six had a major persistent deficit. The ability to walk decreased for all patients who had a nerve palsy. The greatest disability was in the patients who had been forty-eight years old or less and had had a primary total hip replacement (p = 0.037). The prognosis for neurological recovery was related to the degree to which the nerve was damaged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Shoulder arthroplasty for rheumatoid arthritis.

Forty-two Designed After Natural Anatomy (DANA) total shoulder arthroplasties (Howmedica, Rutherford, New Jersey) were performed in 34 rheumatoid patients. Thirty shoulders in 23 patients were followed for a minimum of two years. Twelve of the 30 shoulders (40%) had significant rotator cuff tears. The average rating for pain improved from 3 points preoperatively to 8 points postoperatively for the overall group, and the average rating for function improved from 3 points preoperatively to 6 points postoperatively. Range of motion (ROM) improved substantially in patients treated with a regular glenoid component. Four patients were treated with hooded glenoid components designed to improve stability for shoulders in which the rotator cuff was deficient. In the rotator-cuff-deficient patients, pain and function improved; however, ROM was unchanged. Complications, including one acromial fracture and two loose glenoid components, required revision surgery.

Aged↗

PubMed1991

Long-term follow-up of cemented total hip arthroplasty in rheumatoid arthritis.

Seventy-five primary cemented total hip arthroplasties (THAs) were performed in 53 patients with rheumatoid arthritis and juvenile rheumatoid arthritis. All patients were followed for an average of 7.4 years, unless their prosthetic hips failed before that time. Clinical evaluation was based on a 10-point maximum rating scale, and ratings for pain, walking, function, and activity improved from preoperative values to the most recent follow-up examination. Revision THA was performed for aseptic acetabular loosening in four hips, and femoral loosening in one hip. Sepsis occurred in another four hips. Complications of wound healing occurred in 14 hips. Roentgenographic evidence of loosening was seen in six acetabular components, in three femoral components, and in the femoral and acetabular component of one hip; none of these hips have as yet required revision THA. The Kaplan-Meier survivorship analysis revealed a 93% survival probability at seven years, which fell to 77% at 12 years in these patients. A trend was that younger, larger patients had increased failure and component loosening rates. Cemented primary THA has been a satisfactory operation in the rheumatoid patient. The relatively high rate of wound healing problems and sepsis may be due to the systemic immune nature of rheumatoid arthritis; however, 25% of these prosthetic hips either failed or are at risk for future failure. Thus, improved techniques are still necessary to increase the long-term success of THA in the rheumatoid patient.

Adolescent↗

PubMed1990

Total hip replacement for patients who have ankylosing spondylitis. The importance of the formation of heterotopic bone and of the durability of fixation of cemented components.

Fifty-three total hip replacements were performed in thirty-one patients who had ankylosing spondylitis. After an average period of follow-up of 6.3 years, cemented conventional hip prostheses proved to be very durable in this young population (average age, forty-three years). Only one primary conventional hip prosthesis was revised for aseptic loosening, seventeen years after implantation. Clinically important heterotopic bone (Classes III and IV of Brooker et al.) developed in 11 per cent of the patients, all of whom had had a previous operation on the hip, postoperative infection, or complete ankylosis preoperatively. If a patient has clinically important heterotopic bone after one operation on the hip, and an arthroplasty of the contralateral hip or reoperation on the same hip is to be done, prophylactic treatment should be considered for prevention of formation of heterotopic bone.

Adolescent↗

PubMed1990

Cementless total joint arthroplasty prostheses with titanium-alloy articular surfaces. A human retrieval analysis.

Surgical implants of titanium alloy (Ti-6Al-4V) have been found to be susceptible to abrasive wear, resulting in the well-known phenomenon of metallosis. In the presence of the acrylic debris generated by loose joint arthroplasty prostheses, this abrasive wear is greatly increased. However, the bone loss seen in these cases has generally been presumed to be due to the osteolytic effects of particulate acrylic, not the alloy debris, which has generally been assumed to be biocompatible. To examine the in vivo effects of titanium-alloy wear without the added presence of acrylic debris, a comprehensive analysis was made of cementless human joint arthroplasty prostheses with Ti-6Al-4V alloy surfaces articulating on ultra-high molecular weight polyethylene (UHMWPE). Specimens, including the prostheses, synovium, pseudocapsule and additional soft tissues, and periarticular bone, were retrieved from 22 hips and two knees. Specimens were examined by histologic techniques, energy-dispersive X-ray analysis, and electron microscopy. Serial sections of the implants were evaluated for tissue ingrowth. Tissues surrounding all joints implanted more than one year showed some degree of discoloration indicative of metallosis, whereas after two years the synovium was hypertrophic and villiform. Histologic evaluation showed good fixation by bony ingrowth in the vast majority of cases, although location and extent of ingrowth was dependent on numerous factors. Viability of ingrowth bone was established by fluorochrome labeling. However, despite good biologic fixation, cavitary osteolysis of the bone surrounding the implants was frequently identified. These lesions were filled with sheets of aggressive macrophages within a matrix of fibrous tissue and necrotic debris. Under polarized light the macrophages were found to be filled with alloy and polyethylene fragments of a characteristic size. Osteoblast-mediated remodeling of bone was infrequently observed. Instead, the bone was resorbed along a front in contact with the granulomatous tissues filling the cystic lesions. Visible burnishing was observed on every articular surface, with a linear relationship between wear and time implanted. By one year the surfaces were covered with a characteristic "scratch and gouge" pattern, similar on all sizes of femoral heads as well as the total knee prostheses. This study demonstrates that the combination of Ti-6Al-4V alloy and UHMWPE, when used as a bearing surface combination in total joint arthroplasty prostheses, results in excessive wear of both metal and polymer.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1990

Joint replacement for ankylosed hips.

Forty-one fused hips in thirty-eight patients were converted to total hip replacement. The average length of follow-up was seven years. The predominant indications for conversion were progressively disabling pain in the low back or the hip, or both; loss of function due to immobility or malposition of the hip; and progressive pain and instability of the knee (usually ipsilateral). The postoperative arc of flexion averaged 87 degrees. Limb-length discrepancies improved an average of 2.5 centimeters. Postoperative function of the abductor muscles depended on the preoperative quality of those muscles and on the accuracy of the biomechanical restoration. Postoperative strength of the muscles of the hip improved for two years or more in most patients. There was complete or major relief of pain, improved mobility of the hip, and decreased dependence on supports for walking. There were nine failures: four because of sepsis, four because of loosening of the femoral component, and one because of malposition of the acetabular component. The failures were predominantly in patients who were fifty years old or less at the time of arthroplasty, patients who had had two or more previous operations, and patients who had had an injury to the hip. The quality of the results approached that after primary hip arthroplasty in older patients who have not had multiple previous operations on the hip. Survivorship analysis of the spontaneously fused hips that were treated with conventional hip replacement predicted a probability of survival of the implant of 96 per cent at thirteen years postoperatively (p = 0.048).

Adult↗

PubMed1990

Stem fracture incidence in Trapezoidal-28 stainless steel hip arthroplasty.

From 1970 to March 1978, 716 forged stainless steel Trapezoidal-28 (T-28) total hip arthroplasties were performed at the authors' institution with a follow-up period from one to 15 years (mean, 64 months). There were 13 (1.8%) stem fractures and one (0.1%) neck fracture. Average time to fracture was 95 months. All fractures occurred in stems implanted before 1976, using early femoral acrylic stem fixation techniques. Stem fracture was related to time of surgery, stem size, patient height, patient weight (for males), and patient age. Survivorship analysis predicted an overall ten-year fracture rate of 4%, and a ten-year rate of 5% for T-28 stems implanted before 1976. There have been no reported fractures in the 204 T-28 stainless steel prostheses implanted since 1976. The mean patient follow-up period for the T-28 stems implanted after 1975 was 52 months, and only 16 patients have been followed for nine years or more. Thus, a longer patient follow-up period is needed in the post-1975 group in order to determine the long-term fracture rate in this group. However, the major difference between this group and the early group is the use of an improved cementation technique, as well as the use of larger prostheses when possible. There was no material or manufacturing change until the introduction of the TR-28 prostheses in 1978.

Adolescent↗

PubMed1990

Strength of initial mechanical fixation of screw ring acetabular components.

This study was conducted to determine the effects of design on the initial fixation of several types of screw-ring acetabular components. The components were tested in polyurethane foam to assess relative screw fixation strengths with a consistent material. Embalmed pelves from anatomic specimens were used to conduct paired tests between designs that showed large differences in insertional torque to failure in foam. The quality of the initial fixation in foam was found to be dependent on the design features of the components. Components with widely spaced, deep threads, and minimal thread interruptions offered the strongest initial fixation in foam. Tests in bone revealed a wide range of fixation strengths reflecting the variability in bone quality. No differences in fixation strength attributable to component design were observed in bone. When the insertional failure torque was greater than 60 N.m, one-half of the pelves fractured, and these fractures occurred with all designs. At failure torques less than 60 N.m, failure was predominantly due to thread strippage of the screw, with only two of 20 specimens experiencing pelvic fracture.

Acetabulum↗

PubMed1990

Treatment of osteoarthrosis secondary to congenital dislocation of the hip. Primary cemented surface replacement compared with conventional total hip replacement.

Seventy-four cemented conventional total hip arthroplasties (in fifty-five patients) and thirty-seven cemented surface replacements (in thirty-two patients) were done between 1971 and 1984 for treatment of osteoarthrosis secondary to congenital dislocation of the hip. The patients in the first group were older and had more severe dysplasia. In all patients, we tried to position the acetabular component at the level of the true acetabulum. In both groups, the operation relieved pain and improved the function of the hip in the short term. There were fewer and less severe early postoperative complications in the surface-replacement group, but the rate of long-term failure (revision or resection) was substantially higher. Survivorship analysis demonstrated that neither type of operation yielded durable results in younger patients; all revisions were in patients who were less than sixty years old. However, in older patients who had cemented conventional total hip arthroplasty, survivorship was excellent, regardless of the amount of dysplasia.

Adult↗

PubMed1989

Preliminary results of an off-the-shelf press-fit stem. The anthropometric total hip femoral component using exact-fit principles.

The use of custom-manufactured femoral prostheses as part of routine total hip arthroplasty (THA) has been suggested. However, there are several disadvantages, including possible inaccuracy of fit, inadequate instrumentation, and high cost. A series of 28 THAs (including 18% for revision of failed, cemented THA) using a press-fit prosthesis of contemporary design were investigated. The average follow-up period was 28 months (range, 12-49 months). Clinical results were overall very good, even in revision cases. Roentgenographic changes included rapid femoral remodeling, which may increase component stability. Given the clinical and roentgenographic results obtained in this complex-problem patient population, it is difficult to justify the use of custom femoral components in routine THA.

Adult↗

PubMed1989

The validity of survivorship analysis in total joint arthroplasty.

The use of survivorship analysis requires an assumption that patients who are lost to follow-up are no more or less likely to be at risk of failure of an operation or a procedure than are patients who are still being followed. This is a major assumption in long-term orthopaedic studies, in which a high percentage of patients are usually lost to follow-up. We compared the survivorship curve for the first 100 Tharies replacements done at our institution (which were completed by September 1977), using data that were collected in the standard way up to 1985, through a letter requesting a follow-up visit, with the curve for the same patients that was based on almost complete follow-up data that were gathered by telephone from 1985 on. The similarity of the two curves suggested that the assumptions that are necessary for the validity of survivorship analysis are reasonable, even in the orthopaedic setting, in which many patients are lost to follow-up. The usefulness of the survivorship curve for prediction was also evaluated by comparing the curve based on the first forty-six of the 100 Tharies replacements (before 1977) with the curve based on the last fifty-four such operations (from January 1977 to September 1977). The results of these two comparisons suggest that survivorship analysis is a valid technique to use in the long-term evaluation of patients who have had a joint replacement.

Adult↗