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Biomedical subjects

R C Johnston

Publications and source records attributed to R C Johnston.

At least 19 recordsLinked to original sources
PubMed2000

MAD3 encodes a novel component of the spindle checkpoint which interacts with Bub3p, Cdc20p, and Mad2p.

We show that MAD3 encodes a novel 58-kD nuclear protein which is not essential for viability, but is an integral component of the spindle checkpoint in budding yeast. Sequence analysis reveals two regions of Mad3p that are 46 and 47% identical to sequences in the NH(2)-terminal region of the budding yeast Bub1 protein kinase. Bub1p is known to bind Bub3p (Roberts et al. 1994) and we use two-hybrid assays and coimmunoprecipitation experiments to show that Mad3p can also bind to Bub3p. In addition, we find that Mad3p interacts with Mad2p and the cell cycle regulator Cdc20p. We show that the two regions of homology between Mad3p and Bub1p are crucial for these interactions and identify loss of function mutations within each domain of Mad3p. We discuss roles for Mad3p and its interactions with other spindle checkpoint proteins and with Cdc20p, the target of the checkpoint.

Calcium-Binding Proteins↗
PubMed2000

Charnley total hip arthroplasty with cement. Minimum twenty-five-year follow-up.

BACKGROUND: This report presents the results of the senior author's initial twenty-five-year experience with the use of Charnley total hip arthroplasty with cement. The purpose of this paper was to evaluate the long-term results of total hip arthroplasty. METHODS: Between July 1970 and April 1972, the senior author (R. C. J.) performed 330 Charnley total hip replacements with cement using a hand-packing cement technique in 262 patients. Fifty-one patients (sixty-two hips) who were alive at least twenty-five years post-operatively were evaluated from a clinical standpoint with use of a standard-terminology questionnaire. The average age of this group at the time of surgery was fifty-six years (range, thirty-five to seventy-one years) compared with sixty-five years (range, twenty-one to eighty-nine years) for the entire group. All patients were evaluated for radiographic changes at the time of their most recent follow-up. Of the fifty-one patients (sixty-two hips) who were alive at least twenty-five years postoperatively, thirty-one (thirty-six hips) had a follow-up radiograph made at a minimum of twenty-five years after the surgery. The average duration of radiographic follow-up for the fifty-one patients was 22.7 years (range, two to twenty-seven years). RESULTS: Of the sixty-two hips in the fifty-one patients who were alive at least twenty-five years postoperatively, fourteen (23 percent) had been revised. Three (5 percent) had the revision because of loosening with infection; eleven (18 percent), because of aseptic loosening; and none, because of dislocation. The prevalence of revision due to aseptic loosening of the acetabular component in all 316 hips (excluding those that were lost to follow-up or that were revised for infection or dislocation) was 6 percent (eighteen hips), whereas the prevalence in the fifty-nine hips (excluding the three revised for infection) in the patients who were alive at least twenty-five years after the arthroplasty was 15 percent (nine hips). The prevalence of revision because of aseptic loosening of the femoral component in all 316 hips was 3 percent (nine hips), and the prevalence in the fifty-nine hips in the living patients was 7 percent (four hips). In the group of living patients, osteolysis occurred in Gruen zone 1 or 7 in thirty-three hips and in Gruen zones 2 through 6 in two hips. Ballooning acetabular osteolysis occurred in five hips. Of the 327 hips for which the outcome was known after a minimum of twenty-five years, 295 (90 percent) had retained the original implants until the patient died or until the most recent follow-up examination. Of the sixty-two hips in patients who lived for at least twenty-five years after the surgery, forty-eight (77 percent) had retained the original prosthesis. CONCLUSIONS: Our follow-up study at twenty-five years following Charnley total hip arthroplasty with cement demonstrates the durability of the results of the procedure. These results should provide a means for comparison with the results of newer cementing techniques as well as those associated with newer cemented and cementless hip designs.

Aged↗
PubMed2000

Cemented rotating-platform total knee replacement. A nine to twelve-year follow-up study.

BACKGROUND: Although the LCS (low contact stress) rotating-platform mobile-bearing knee replacement has been used extensively, there have been few intermediate or long-term clinical and radiographic follow-up studies evaluating the device. The purpose of this study was to report the nine to twelve-year results of a consecutive series of patients who had a primary total knee replacement performed with this device. METHODS: Between November 1985 and November 1988, the senior author (R. C. J.) performed 119 consecutive total knee arthroplasties in eighty-six patients with LCS rotating-platform femoral and tibial components and a Townley all-polyethylene dome patellar component. All components were fixed with cement. The average age of the patients at the time of the operation was seventy years (range, thirty-seven to eighty-eight years). Fifty-two patients (seventy-six knees) were female, and thirty-four patients (forty-three knees) were male. The patients were evaluated with clinical knee ratings and radiographic analysis nine to twelve years following the knee replacement. RESULTS: At the time of the nine to twelve-year follow-up, sixty-four patients (eighty-six knees) were alive, eighteen patients (twenty-eight knees) had died, and four patients (five knees) had been lost to follow-up. Of the 114 knees in the eighty-two patients for whom the final outcome was known, none required a reoperation and none had a dislocation of the mobile-bearing prosthesis. For the forty-five patients (sixty-six knees) who returned for final clinical and radiographic follow-up examinations at nine to twelve years, the average clinical and functional Knee Society ratings were 30 points (range, 2 to 70 points) and 44 points (range, 0 to 80 points) preoperatively and 90 points (range, 63 to 102 points) and 75 points (range, 30 to 100 points) at the final follow-up evaluation. The average Hospital for Special Surgery knee rating was 57 points (range, 28 to 80 points) preoperatively and 84 points (range, 59 to 97 points) at the final follow-up evaluation. The average active range of knee flexion was from 0 degrees (range, 0 to 10 degrees) to 102 degrees (range, 15 to 120 degrees) at the final follow-up evaluation. Seven of the sixty-six knees were painful anteriorly. There was no periprosthetic osteolysis and no evidence of loosening on follow-up radiographs. CONCLUSIONS: After nine to twelve years of follow-up, the cemented LCS rotating-platform knee replacement was found to be performing well, with durable clinical and radiographic results.

Adult↗
PubMed1999

The John Charnley Award. Practice surveillance: a practical method to assess outcome and to perform clinical research.

The senior author systematically began collecting preoperative and postoperative data on all the total hip arthroplasties he performed starting in July 1970. The data collected represent a 26-year experience using practice surveillance (preoperative and regular interval postoperative collection and analysis of outcomes) as a method to document the outcome of the total hip arthroplasty procedure and as a method to evaluate the need for changes in the procedure. As the senior author made few selected changes in the operative procedure during the followup period, the primary author has been able to evaluate the change in outcome based on these changes. The six studies reported in the current study show the durability of the long-term results of cemented total hip arthroplasty, the improvement in radiographic reproducibility obtained on the femoral side of the construct with improved cementing techniques, the deleterious effects of using cable to reattach the greater trochanter, the deleterious effects of changing femoral component design that included a change in surface finish, the improvement in acetabular fixation using cementless fixation, and the optimization of bearing surface wear using smaller diameter femoral heads. All of these findings have been incorporated into the primary surgeon's practice based on this practice surveillance. As shown, practice surveillance also has provided a tool for performing clinical research. Although practice surveillance of controlled cohorts never will supplant prospective randomized clinical trials in evidence based medicine, it should help each surgeon with his or her own practice and can be used as an important research tool to study the optimization of outcomes of a surgical procedure.

Adult↗
PubMed1999

One-stage revision surgery of the infected hip. A minimum 10-year followup study.

Between 1977 and 1983, 24 one-stage revision surgeries were performed for septic failure of a total hip arthroplasty in 24 patients by one surgeon. Twelve patients died and none were lost to followup at a minimum of 10 years after the procedure. Infection reoccurred around two hips (8.3%). If the selected criteria (patients without draining sinuses, without immunocompromise, and with adequate bone quality after debridement) and the standard approach (meticulous debridement, use of antibiotic-impregnated cement, and use of 3 to 6 months postoperative oral antibiotic therapy) used in this study are implemented, direct exchange of an infected total hip arthroplasty construct is a reasonable and cost-effective alternative for some patients with infection after total hip arthroplasty.

Adult↗
PubMed1999

The effects of surface roughness and polymethylmethacrylate precoating on the radiographic and clinical results of the Iowa hip prosthesis. A study of patients less than fifty years old.

BACKGROUND: The purpose of the present study was to compare the results associated with two different surface finishes (bead-blasted and grit-blasted) for Iowa femoral components used in total hip arthroplasties performed between January 1979 and June 1991 in patients who were less than fifty years old. METHODS: Between January 1979 and December 1985, thirty-six primary total hip replacements were performed in twenty-five patients with insertion of a bead-blasted Iowa femoral component (average surface roughness, 0.8 micrometer) with cement and insertion of a titanium-backed acetabular component (thirty-five hips) or non-metal-backed acetabular component (one hip) with cement. Between January 1986 and June 1991, forty-five primary total hip replacements were performed in thirty-seven patients with use of a precoated grit-blasted Iowa femoral component (average surface roughness, 2.1 micrometers) and a Harris-Galante-I porous ingrowth acetabular component (forty-one hips) or an Osteonics component (four hips). The only change in the design of the femoral component (other than the surface finish) between the two consecutive series was the addition of polymethylmethacrylate precoating to the proximal third of all forty-five grit-blasted stems and modularity of the femoral head of the last eight grit-blasted stems. RESULTS: No hip was lost to follow-up. The duration of radiographic follow-up of the hips treated with the bead-blasted component averaged 11.3 years (range, ten to sixteen years) postoperatively, whereas that of the hips treated with the precoated grit-blasted component averaged 8.2 years (range, five to eleven years). Two (6 percent) of the bead-blasted femoral components were revised because of aseptic loosening compared with eight (18 percent) of the precoated grit-blasted components. Four bead-blasted components (11 percent) were either radiographically loose or were revised because of loosening compared with eleven precoated grit-blasted components (24 percent). Kaplan-Meier survivorship curves evaluated with log-rank analysis revealed that the bead-blasted Iowa femoral components were revised because of aseptic loosening (p = 0.0184) and were radiographically loose (p = 0.0068) less often than the precoated grit-blasted Iowa femoral components. CONCLUSIONS: The findings of the present study have led the senior ones of us to resume using femoral components with a polished surface and fixed with cement.

Adolescent↗
PubMed1999

Unicompartmental knee replacement. A minimum 15 year followup study.

One hundred forty Marmor cemented unicompartmental knee replacements were inserted in 103 patients between 1975 and 1982. Fifty-two patients were women and 51 were men. One hundred twenty-five were medial compartment knee replacements and 15 were lateral knee replacements. At minimum 15 year followup 34 patients with 48 knee replacements were living; only four patients with four knee replacements were lost to followup. Average preoperative and final followup Hospital for Special Surgery knee scores were 57 and 82 points, respectively for the knees of living patients. Average preoperative and final followup Knee Society clinical and Knee Society functional scores were 31 and 42, and 85 and 71 points, respectively. For all knees, 10.2% (14 knees) were revised [4.4% (six knees) for tibial loosening, 5.1% (seven knees) for disease progression, and .7% (one knee) for pain]. For patients living 15 years, 12.5% (six knees) were revised [2.1% (one knee) for tibial loosening, and 10.4% (five knees) for disease progression]. Revision for failure of fixation of these unicompartmental replacements was comparable with that reported for fixed bearing total knee replacement. Disease progression (46%; 62 of 136 knees) and tibial subsidence with wear (10.4%; 15 of 136 knees, five of which required revision) were the major long term problems in this group of patients.

Activities of Daily Living↗
PubMed1998

Hybrid total hip arthroplasty in patients under the age of fifty: a five- to ten-year follow-up.

In 37 patients, 45 total hip replacements were performed using contemporary cementing techniques, an uncemented Harris-Galante I acetabular component and a cemented precoated Iowa femoral component in patients under the age of 50 at the time of their surgery; 36 patients with 43 hybrid hips were living, 1 patient with 2 hybrid hips was decreased. No patients were lost to follow-up. At 5- to 10-year follow-up, eight hips were revised for aseptic loosening. No acetabular components, and eight femoral components (18%) were revised for aseptic loosening. When looking at radiographic results, including revision as well as those components that were probably or definitely loose on radiographs, 0 acetabular components and 11 femoral components (24%) were radiographically loose. These results demonstrate the excellent durability of the uncemented Harris-Galante acetabular component in the younger patient. However, the Iowa grit-blasted methyl methacrylate precoated femoral component had a magnitude increase in the prevalence of revision for aseptic femoral loosening when compared to the senior author's long-term Charnley results in this age group. The authors attribute the failure to the rough surface finish applied to the femoral component. However, the polymethyl methacrylate proximal precoating and the femoral component design may also contribute to the femoral failures.

Adult↗
PubMed1998

Salvage of total hip instability with a constrained acetabular component.

Between April 1988 and February 1993, 101 constraining acetabular components were implanted into 98 patients. One patient was lost to followup at 8 months. Otherwise, all patients were observed until death or for at least 2 years minimum followup. The average clinical followup for the living patients was 61 months (range, 24-97 months). Indications for the use of the constrained acetabular components were recurrent dislocation (an average of six dislocations, range 2-20) in 56 cases, intraoperative instability in 38 cases, and neurologic impairment in seven cases. For the entire group there were four cases of recurrent dislocation or failure of the component (4%). For the cases where this component was used for recurrent dislocation, 96% (54 of 56 cases) had no additional dislocations. Radiographically, at this short term followup, there was no evidence of an increased incidence of femoral or acetabular component loosening. The authors recommend judicious use of this component as a salvage measure for desperate cases of hip instability during or after total hip arthroplasty.

Acetabulum↗
PubMed1998

Salvage of a recurrently dislocating total hip prosthesis with use of a constrained acetabular component. A retrospective analysis of fifty-six cases.

Fifty-six constrained acetabular components were placed, between April 1988 and February 1993, in fifty-five patients who had had recurrent dislocations (average, six dislocations; range, two to twenty dislocations) of the femoral component after a previous total hip arthroplasty. All patients had additional factors contributing to the instability of the implant, including absence or disruption of the abductor mechanism, poor health, mental retardation, confusion, and Alzheimer disease. One patient was lost to follow-up. The remaining patients were followed clinically for a minimum of three years (average, sixty-four months; range, thirty-seven to ninety-seven months) or until the time of death. During the follow-up interval, only two (4 per cent) of the fifty-five patients had a subsequent dislocation. The use of this type of component should be considered for patients who have recurrent dislocation if other treatment modalities are unlikely to be effective.

Acetabulum↗
PubMed1998

Charnley total hip arthroplasty in patients less than fifty years old. A twenty to twenty-five-year follow-up note.

We evaluated the results twenty to twenty-five years after ninety-three consecutive, nonselected Charnley total hip arthroplasties performed with cement by the senior one of us in sixty-nine patients who were less than fifty years old at the time of the procedure. Seventy of the seventy-two hips in the living patients were followed radiographically for at least twenty years. Twenty-seven hips (29 per cent) had a revision or a resection of the prosthesis during the follow-up period. The revision or the resection was performed because of aseptic loosening in twenty-one hips (23 per cent), infection in four (4 per cent), dislocation in one (1 per cent), and fracture of the femur in one. Eighteen acetabular components (19 per cent) and five femoral components (5 per cent) were revised because of aseptic loosening, and an additional fourteen acetabular components (15 per cent) and seven femoral components (8 per cent) demonstrated definite or probable radiographic loosening. The present study demonstrates the long-term durability of total hip arthroplasty performed with cement in an active population of patients. The fixation of the femoral component was found to perform better than that of the acetabular component at twenty to twenty-five years after the procedure.

Adolescent↗
PubMed1998

Total hip arthroplasty with cement in patients who have rheumatoid arthritis. A minimum ten-year follow-up study.

One hundred and six consecutive total hip arthroplasties with cement were performed by one surgeon, at least ten years before the time of the present clinical and radiographic review, in seventy-five patients who had adult-onset rheumatoid arthritis. Two patients (three hips) were lost to follow-up. Seven (7 per cent) of the remaining 103 hips were revised. The revisions were performed because of infection (three hips), dislocation (two hips), or aseptic loosening (two hips). Of the ninety-eight hips that were not lost to follow-up or revised because of infection or dislocation, eight (8 per cent) had radiographic loosening of the acetabular component and two (2 per cent) had radiographic loosening of the femoral component. Although the prevalence of radiographic loosening of the acetabular component was four times greater than the prevalence of radiographic loosening of the femoral component, the prevalence of revision because of aseptic loosening of the acetabular component was identical to that for the femoral component (one component each). These results compared favorably with those of total hip arthroplasty with cement, performed by the same surgeon, for the treatment of other diagnoses. Loosening of the acetabular component was significantly associated with a younger age at the time of the index operation (p = 0.03) and with acetabular osteolysis (p = 0.0006). Of forty-eight hips in thirty-two patients who survived for at least ten years, 96 per cent (forty-six hips) were considered by the patients to have a satisfactory result. At the time of the latest follow-up, twenty-four (75 per cent) of the patients had no pain in the hip. Although eighteen patients (56 per cent) could walk without support at a minimum of ten years after the operation, we found that the functional results for patients who had rheumatoid arthritis were inferior to those observed for patients who had had a total hip arthroplasty with cement, performed by the same surgeon, for the treatment of other diagnoses.

Acetabulum↗
PubMed1997

Long-term results of revision total hip arthroplasty with improved cementing technique.

We performed 83 consecutive cemented revision total hip arthroplasties in 77 patients between 1977 and 1983 using improved cementing techniques. One patient (two hips) was lost to follow-up. The remaining 76 patients (81 hips) had an average age at revision of 63.7 years (23 to 89). At the final follow-up 18 hips (22%) had had a reoperation, two (2.5%) for sepsis, three (4%) for dislocation and 13 (16%) for aseptic loosening. The incidence of rerevision for aseptic femoral loosening was 5.4% and for aseptic acetabular loosening 16%. These results confirm that cemented femoral revision is a durable option in revision hip surgery when improved cementing techniques are used, but that cemented acetabular revision is unsatisfactory.

Acetabulum↗
PubMed1997

Charnley total hip arthroplasty with use of improved techniques of cementing. The results after a minimum of fifteen years of follow-up.

Three hundred and fifty-seven consecutive Charnley total hip arthroplasties were performed in 320 patients with use of a so-called second-generation technique of cementing between July 1976 and June 1978. This technique includes use of a distal femoral intramedullary cement plug, hand-mixing of the cement, and use of a cement gun to deliver the cement into the femoral canal in a retrograde fashion. At the time of the latest follow-up evaluation, a minimum of fifteen years after the arthroplasty, 130 patients (142 hips) were still alive, 189 patients (214 hips) had died, and one patient (one hip) had been lost to follow-up. A radiograph was made for 116 (82 per cent) of the 142 hips in the 130 surviving patients. Of the 356 hips that had not been lost to follow-up, thirty-three (9 per cent) had had a revision and two (1 per cent), a Girdlestone resection arthroplasty during the follow-up period. Nineteen hips (5 per cent) were revised because of aseptic loosening of the femoral or acetabular component, or both (two hips); seven (2 per cent), because of loosening with infection; and seven (2 per cent), because of dislocation. The two resection arthroplasties were performed because of loosening with infection; both were done in patients who died before the time of the latest follow-up evaluation. Of the 142 hips in the 130 patients who were alive at a minimum of fifteen years, twenty-two (15 per cent) had been revised: fifteen (11 per cent), because of aseptic loosening; three (2 per cent), because of loosening with infection; and four (3 per cent), because of dislocation. Revision of the femoral component because of aseptic loosening (excluding components that were revised because of dislocation or infection) was performed in four (1 per cent) of the entire series of 356 hips and in three (2 per cent) of the 142 hips in the 130 patients who survived for at least fifteen years. Two of the 356 hips and two of the 142 hips had aseptic loosening of the acetabular as well as the femoral component at the time of the revision. Loosening of the femoral component, defined as aseptic loosening leading to revision or as definite or probable radiographic loosening, occurred in ten (3 per cent) of the 356 hips and in six (5 per cent) of the 116 hips for which radiographs were made at a minimum of fifteen years. The acetabular component was revised because of aseptic loosening in seventeen (5 per cent) of the entire series of 356 hips and in fourteen (10 per cent) of the 142 hips in the 130 patients who survived for at least fifteen years. The acetabular component loosened without infection in forty-one (12 per cent) of the 356 hips and in twenty-six (22 per cent) of the 116 hips for which radiographs were made at a minimum of fifteen years. In two of these patients, the femoral component was also revised. Thus, of the entire series of 356 hips, two had a revision of the femoral component alone because of aseptic loosening; fifteen, a revision of the acetabular component alone; and two, a revision of both components. Of the 142 hips in the 130 patients who survived for at least fifteen years, one was revised for loosening of the femoral component alone; twelve, for loosening of the acetabular component alone; and two, for loosening of both components. These findings demonstrate long-term durability of fixation of the femoral component but less reliable fixation of the acetabular component, even when the surgeon is experienced and improved techniques of cementing are used.

Activities of Daily Living↗
PubMed1997

The Frank Stinchfield Award. Contribution of cable debris generation to accelerated polyethylene wear.

The decision of the senior author of a large total hip replacement practice to switch from wire to braided cable for reattachment of the greater trochanter provided the opportunity to evaluate the long term effects (on acetabular component wear, osteolysis, and component loosening) caused by the introduction of metallic debris (generated by cable fretting and breakage) into the total hip arthroplasty construct. Seven hundred and nine consecutive primary total hip arthroplasties were performed during a 5-year period and followed up for a minimum of 10 years. Wire and cable reattachment of the greater trochanter was used sequentially. At minimum 10-year followup the cable group had significantly more wear, osteolysis, and acetabular radiographic evidence of loosening. Those involved in the design and use of total hip arthroplasty devices must minimize potential sources of metallic debris and other potential sources for third body wear in the total hip arthroplasty construct to help ensure longevity of the arthroplasty.

Adolescent↗
PubMed1997

Total hip arthroplasty in the young adult.

The durability of cemented and hybrid total hip arthroplasty in the young adult was evaluated. A consecutive series of primary cemented total hip arthroplasties performed between 1970 and 1976, and a consecutive series of primary hybrid total hip arthroplasties performed between 1986 and 1991, were evaluated for revision and radiographic loosening of the components. All patients were younger than 50 years of age at the time of surgery and all surgery was performed by one surgeon. At minimum 20 years followup of the cemented group (93 hips in 69 patients) 22% of hips (21 hips) were revised for aseptic loosening (5% of femoral components, five hips, and 19% of acetabular components, 18 hips). At 5- to 10-year followup of the hybrid group (45 hips in 37 patients) 18% of hips (eight hips) were revised for aseptic loosening (18% of femoral components, eight hips, and 0% of acetabular components, 0 hips). Although the cemented femoral component used in the hybrid series showed a marked increase in revision and loosening compared with the cemented series, the excellent fixation obtained with uncemented acetabular components has encouraged the authors to continue the use of hybrid fixation in the young adult. However, the femoral component has been modified to incorporate a polished surface finish and a stem geometry similar to the Charnley flat back prosthesis used in the cemented series.

Adult↗