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Biomedical subjects

C H Rorabeck

Publications and source records attributed to C H Rorabeck.

At least 73 records · Page 4Linked to original sources
PubMed1996

Uncemented revision total hip arthroplasty: a 4-to-6-year review.

A review of 52 cementless revision total hip arthroplasties in 51 patients with a 4- to 6-year clinical and radiographic followup was conducted. Mallory Head titanium alloy prostheses using proximally porous-coated femoral stems were used in all cases. There were 2 revisions of the femoral component only and 1 was an acetabular revision. At an average followup of 4.6 years, 5 (10%) unstable femoral stems had been rerevised and another 7 (14%) stems were unstable radiographically, but rerevision had been refused or postponed. Three (6%) sockets were considered unstable but no acetabular revisions have been done. Eleven of the 12 stem failures were in femora with moderate or severe prerevision femoral bone loss. The Harris Hip Score averaged 76 points for the entire group, and scores were much worse in patients with preexisting femoral bone deficiency. Twenty (40%) femoral fractures occurred during stem insertion. This short-term study shows inadequate fixation of proximally porous-coated femoral stems in revisions with femoral bone loss; adequate stability is achieved if bone loss is limited. Porous-coated acetabular fixation using fins and screws where necessary is adequate in the majority of cases.

Adult↗
PubMed1996

What is the best way of assessing outcome after total knee replacement?

Variable definitions of outcome have been used in the past to assess the results after total joint replacement surgery. These differ in their approach to the measurement of outcome but all must be valid (they measure what they are designed to measure), reliable (they consistently produce the same score), and responsive (able to detect changes that may occur during a period). Responsiveness is crucial to distinguish those patients who benefit from a procedure from those who do not, and a more responsive test will theoretically be able to identify more subtle changes in patient status. The responsiveness of 6 different scoring systems was compared. The results are based on a cohort of 71 patients undergoing total knee arthroplasty in a 7-month period. Responsiveness was determined by performing a paired t test among each patient's scores at 0, 3, and 6 months. The size of the resulting t value represented the comparative responsiveness of the 6 tests. The highest value achieved was with the Western Ontario and McMaster Universities osteoarthritis index and the Knee Society clinical rating scale. The worst scores were achieved by Short Form-36 and time trade off, a utility method of measurement. If small differences between groups of patients are to be shown, measures of outcome that are more responsive to patient change should be used.

Activities of Daily Living↗
PubMed1996

Intra-articular injection of bupivacaine in knee-replacement operations. Results of use for analgesia and for preemptive blockade.

The effectiveness of an intra-articular injection of bupivacaine, administered before the incision or after closure of the wound, was studied in an effort to decrease the need for postoperative narcotics and to improve analgesia for patients who have elective knee replacement. Eighty-two patients received two intra-articular injections in a random, double blind fashion. Twenty-eight of them received thirty milliliters of 0.5 percent bupivacaine and 1:200,000 epinephrine in saline solution before the incision and an injection of thirty milliliters of plain saline solution after closure of the wound (Group 1). Twenty-seven patients received an injection of thirty milliliters of plain saline solution before the incision and thirty milliliters of 0.5 percent bupivacaine and 1:200,000 epinephrine in saline solution after closure of the wound (Group 2). Twenty-seven patients were given thirty milliliters of plain saline solution (a placebo) for both injections (Group 3). The patients who had received bupivacaine after closure of the wound (Group 2) used less morphine from the patient-controlled analgesia pumps than the patients who had received bupivacaine before the incision (Group 1) and the patients who had received the placebo (Group 3). In the first twenty-four hours after the operation, the administration of morphine (mean and standard deviation) was 59 +/- 27 milligrams for Group 2 compared with 68 +/- 30 milligrams for Group 1 (p = 0.26) and 81 +/- 30 milligrams for Group 3 (p = 0.006). At the time of discharge from the hospital, the patients in Group 2 also had a significantly greater mean range of motion (85.2 +/- 8.0 degrees) compared with that of the patients in Groups 1 (80.6 +/- 6.8 degrees, p = 0.02) and 3 (80.1 +/- 6.2 degrees, p = 0.009). However, there was no difference among the groups with respect to the effectiveness of the analgesia, as measured with use of either the visual-analog or the verbal pain-rating scale, or in the prevalence of side effects, including somnolence, urinary retention, nausea and vomiting, or pruritus. Serum concentrations of bupivacaine were well below toxic levels. It was our conclusion that that and intra-articular injection of thirty milliliters of 0.5 percent bupivacaine and 1:200,000 epinephrine in saline solution after closure of the wound decreases the need for narcotics and increases the range of motion after an elective knee replacement. The clinical importance of the amount of increased motion is questionable and needs long-term monitoring.

Analgesics↗
PubMed1996

A tapered titanium femoral stem inserted without cement in a total hip arthroplasty. Radiographic evaluation and stability.

The results of 416 total hip arthroplasties performed in 372 patients with insertion of a Mallory-Head titanium femoral component without cement were reviewed retrospectively, to determine the stability and the radiographic parameters of stability for this type of stem. The average duration of clinical and radiographic follow-up was 3.7 years (range, 2.0 to 6.5 years). No revisions were performed to treat instability of the stem, pain, or osteolysis by the time of the latest follow-up examination. Although the clinical results were excellent, the radiographic signs of fixation that have been well described for chromium-cobalt stems were frequently absent. So-called endosteal spot welds, commonly seen in association with long, extensively coated stems, were seen infrequently. Resorptive bone-remodeling rarely extended beyond zones 1 and 7 of Gruen et al. Both endosteal and periosteal distal cortical hypertrophy was common, but the cause was unknown. Osteolysis of the distal aspect of the femur, shedding of the porous coating, and breakage of the stem were not seen. Forty-four stems (11 per cent) had initial subsidence; however, it nearly always stabilized within six months postoperatively and did not affect the eventual stability at the time of the short-term follow-up. The short-term clinical outcome confirmed the stability of these stems that had been determined from the radiographic findings and the lack of revisions. At the latest follow-up examination, 323 (87 per cent) of the patients (362 [87 per cent] of the hips) had no or slight pain in the lower limb over-all and only twenty-two (6 per cent) of the patients (twenty-seven [6 per cent] of the hips) had pain in the thigh. This tapered titanium femoral component appears to provide excellent short-term stability, without resorptive bone-remodeling, osteolysis, or a high prevalence of pain in the thigh. Radiographic evaluation of stability of this stem is clearly different from that of chromium-cobalt stems-particularly extensively coated anatomic medullary locking stems-in that so-called spot welds and severe resorptive bone changes were uncommon and distal cortical hypertrophy was common.

Adolescent↗
PubMed1996

Interpretation by radiologists of orthopedic total joint radiographs: is it necessary or cost-effective?

OBJECTIVE: To examine the necessity and cost-effectiveness of interpretation by radiologists of orthopedic radiographs obtained for patients who undergo total hip or knee replacement. DESIGN: A prospective study. Serial preoperative and postoperative x-ray films of the joint in patients scheduled to undergo total hip or knee joint replacement during one calendar year were interpreted by both radiology and orthopedic department staff and compared. Intraoperative findings were used to confirm the radiologic interpretation. The follow-up was 1 year. SETTING: A university teaching hospital. INTERVENTIONS: Primary or revision total hip or knee replacement. MAIN OUTCOME MEASURES: Differences in interpretation of radiographs by radiologists and orthopedic surgeons for any of the four procedures. A change in orthopedic management. RESULTS: For preoperative radiographs, there were no discrepancies between the radiologists and orthopedic surgeons with respect to primary joint replacement. For 100 revision procedures there were 15 discrepancies, but in all cases the orthopedic surgeon's interpretation proved to be correct. For the postoperative radiographs, there were no discrepancies in the group of revision hip replacements. For the other three groups there were a total of six discrepancies and in all cases the orthopedic surgeon's interpretation was correct. In two cases conditions were present that were not recognized by staff from either the radiology department or orthopedic department. CONCLUSION: Interpretation by radiologists of total joint radiographs in patients who undergo primary or revision total hip or knee replacement arthroplasty is not necessary or cost-effective.

Canada↗
PubMed1996

The Nicolas Andry award: comparative results of cemented and cementless total hip arthroplasty.

A prospective randomized clinical trial comparing cemented to cementless total hip arthroplasty has been ongoing at the author's institution since 1987. All parameters assessed showed that there was no statistically significant difference in any of the health related quality of life measures used when patients with cement were compared with patients without cement at any of the followup periods as many as 4 years later. The improvement was dramatic and sustained. No components (cemented or cementless) have been revised to date (average, 4.8 years). A radiographic analysis showed probable loosening of the cemented socket in 24% and presumed minimal pelvic osteolysis in 8%. The cementless sockets showed a greater frequency and severity of pelvic osteolysis (14%). The cemented femoral component was judged to be possibly loose in 10%; however, none were considered probably loose. The patients who had cementless femoral components were doing extremely well with the components showing very little subsidence or proximal stress protection noted. Osteolysis on the femoral side was not seen in any of the cementless stems. Total hip replacement gives comparable clinical results when health related quality of life measures are analyzed; however, metal backed cemented acetabular components have a high rate of radiographic failure. Short-term stability of a non-cemented porous coated titanium stem, however, gave excellent clinical and radiographic results.

Aged↗
PubMed1996

Results of the cementless Mallory-Head primary total hip arthroplasty: a 5 to 7 year review.

We reviewed the results of 172 plasma-sprayed, titanium primary total hip arthroplasties inserted without cement and followed 5 to 7 years. Hips were replaced for a wide range of diagnoses and patient ages. No femoral components had been revised nor were any considered unstable. Clinical results have been excellent; 88% of hips had either no or slight amount of pain and only 5% of patients had thigh pain when specifically asked. Radiographically, this femoral component achieved stability after an initial subsidence in 9% of cases. Extensive femoral bone resorption was rare, and distal cortical hypertrophy was commonly seen. Pelvic osteolysis occurred in 16 (9%) cases and was considered major in 10 of these. It was the cause of failure of 3 acetabular components. Femoral endosteal lysis was not observed. We concluded that mechanical stability of the Mallory-Head titanium total hip prostheses is excellent. However, significant pelvic osteolysis had occurred commonly with this implant design, and will continue to pose major reconstructive problems in the future.

Adult↗
PubMed1995

Aprotinin decreases blood loss in patients undergoing revision or bilateral total hip arthroplasty.

Two recent studies have shown decreased blood loss in patients given aprotinin undergoing primary hip replacement surgery. Because patients undergoing bilateral (bTHA) or revision total hip arthroplasty (rTHA) suffer more blood loss than those undergoing primary THA, we studied consecutive patients undergoing bTHA or rTHA who were randomized to receive either a blinded solution of 3.8 x 10(6) Kallikrein inactivation units (KIU) aprotinin (n = 29) or placebo (n = 24) throughout the surgical procedure. Total blood loss, measured as intraoperative suction losses, weight of sponges, and postoperative volumetric drainage, was compared between groups. Aprotinin patients had significantly less total blood loss 1498 +/- 110 mL (mean +/- SEM) versus 2096 +/- 223 (P = 0.022), and transfused patients in the aprotinin group received fewer packed red blood cells than placebo-treated patients (confidence interval for the difference -1.69, -0.07). In addition, assessment of biochemical markers of hepatic and renal function did not disclose any clinically important differences between groups. Patients were also assessed for development of deep venous thrombosis (DVT) by preoperative and predischarge bilateral lower limb compression ultrasound. None of the aprotinin-treated patients and three placebo-treated patients demonstrated DVT. Unless this trend for decreased DVT with aprotinin can be confirmed, it is questionable whether the slight reduction in blood loss justifies routine use of this expensive drug.

Aged↗
PubMed1995

Resurfacing versus not resurfacing the patella during total knee replacement.

One hundred patients with osteoarthritic knees were randomized either to have their patella resurfaced or not resurfaced using the same total knee replacement. These patients were assessed preoperatively and a minimum 2 years postoperatively using disease-specific (Knee Society Clinical Rating System) and functional capacity (30 second stair climbing and knee flexor and extensor torques) outcome measures. Two patients in the not resurfaced group required reoperation because of anterior knee pain. At 2 years' followup, the not resurfaced group had significantly less pain and better knee flexor torques than did the resurfaced group, whereas the results of the Knee Society Function Scores, 30 second stair climbing, and knee extensor torques were similar. These results suggest that longer-term followup is required, but that one should keep an open mind regarding patellar resurfacing during total knee replacement.

Activities of Daily Living↗
PubMed1995

Screw osteolysis after cementless total knee replacement.

A comparative radiographic review of 217 cementless total knee replacements was done 4 years after surgery to look for radiographic change at the screw-bone interface. There were 102 Miller Galante I knee prostheses, 59 Miller Galante II prostheses, and 56 Anatomic Modular Knee prostheses studied. If the appearance of the screw-bone interface had changed, this was classified according to the width of the lucency. Two hundred sixty-five of the 851 screws that were studied showed some evidence of change, with 185 (21.7%) of the screws showing a cavitary appearance change. The AMK prosthesis showed the higher incidence of cystic and cavitary changes. Polyethylene debris is thought to be responsible for generation of osteolysis and the radiographic appearance change. Design of the components and particularly the polyethylene attachment mechanisms may be responsible for the differences in the frequencies of osteolysis.

Bone Screws↗
PubMed1995

Catastrophic osteolysis in total knee replacement. A report of 17 cases.

One hundred eighty-five total knee revisions were done by the 2 senior authors from 1988 to 1994. Of these, 17 patients were identified as having severe osteolysis. The average age was 62.7 years, and the average weight was 90.8 g. All patients had osteoarthritis. Preoperative aspiration was negative in all patients. Eight patients had a metal-backed patella, 8 had a cementless implant, 4 had a cemented implant, and 5 had a hybrid implant. The average time interval from the index surgery to radiographic evidence of lysis was 56 months. Radiographic review showed gross polyethylene wear in 10 patients, loose tibial implants in 8, fractured baseplates in 2, and evidence of a metallic synovitis in 2. Retrieved polyethylene liners had a average thickness of 7 mm, and none were conforming. Osteolytic defects were defined and classified according to Engh's criteria. The histology showed a foreign body reaction with intracellular refractile polyethylene particles. Four cases had metallic debris. The exposure at the time of revision required a rectus snip in 4, V-Y-quadricepsplasty in 2, and tibial tubercle osteotomy in 1. Posterior stabilized implants were used in 65% and a constrained implant in 30%. Lytic defects were reconstructed with cement only in 47% of knees, allograft in 30%, and metallic wedges in 35%. Based on this report, the authors conclude that younger, overweight patients seem to be at higher risk of implant failure and that osteolysis is not restricted to cementless implants. Furthermore, because review of the radiographs leads to a constant underestimation of the lytic defect, the surgeon must be prepared to deal with complex revisions.

Aged↗
PubMed1995

Measurement of polyethylene wear in metal-backed acetabular cups. I. Three-dimensional technique.

A new technique, the 3-dimensional technique, has been developed. Using a digitzer, points taken from anteroposterior and lateral radiographs are input into a personal computer. A 3-dimensional solid model of the prosthesis is created using custom software. Tilt and anteversion of the acetabular cup are measured, and the model is rotated to a standard frontal view, allowing measurement of femoral head displacement from the center of the acetabular cup. Comparing serial radiographs of the same patient gives the direction and distance of femoral head displacement over time, and this value is used to calculate the minimum volume of polyethylene debris generated. The 3-dimensional technique has been validated by construction of a precision acrylic phantom, and milling of a metal-backed acetabular cup to simulate polyethylene wear. Three-dimensional measurement of femoral head displacement using this technique has an accuracy of +/- 0.15 mm, and volume calculations are within 8% of the true amount of polyethylene removed from the cup. The 3-dimensional technique gives previously unavailable information, and can be used for clinical evaluation of polyethylene wear and evaluation of new prosthetic designs and bearing surfaces.

Acetabulum↗
PubMed1995

Measurement of polyethylene wear in metal-backed acetabular cups. II. Clinical application.

The new 3-dimensional technique was applied to the radiographs of 141 patients who had received Porous Coated Anatomic total hip prostheses. Values were obtained for the position of the acetabular cup, the 3-dimensional distance and direction of femoral head displacement, and the minimum volume of polyethylene debris produced. Mean age of the patients at the time of replacement was 61 years old; mean followup was 5.6 years (range, 4-7.2 years). Change in the position of the femoral head between initial and long-term followup films was assumed to represent polyethylene wear, and formulas were used to calculate the minimal volume of polyethylene debris produced. The overall rate of 3-dimensional femoral head displacement was 0.264 mm per year, almost twice that usually quoted in the current literature for 2-dimensional linear wear. A significant contribution to this value was made by anterior and posterior displacement. Two-dimensional femoral head displacement (measured in the plane of anteroposterior radiographs) on the same patients was 0.149 mm per year. The mean minimum volume of polyethylene debris produced after 5.6 years was 0.448 cm3 (range, 0.00-2.83 cm3), giving a mean rate of 0.079 cm3 polyethylene debris produced each year. Thirteen patients in this series had radiologic osteolysis and a significantly greater femoral head displacement and polyethylene volumetric wear than those with no osteolysis. Patients with a 32-mm femoral head diameter and a polyethylene linear < 1 cm thick had a significantly greater amount of polyethylene wear. This series gives previously unavailable data on 3-dimensional femoral head displacement and is the first report that correlates the minimum volume of polyethylene wear produced with radiologic osteolysis.

Acetabulum↗