Abstract
Sixty-one consecutive so-called hybrid revision total hip arthroplasties were performed in fifty-five patients by one surgeon, from 1986 through 1988, for mechanical failure of a cemented total hip prosthesis. In all of the patients, the acetabular and femoral components were revised to a porous-coated Harris-Galante acetabular component inserted without cement and an Iowa femoral component inserted with cement. Contemporary cementing techniques were used, but structural bone graft was not. The over-all prevalence of repeat revision for aseptic loosening was 0 per cent for the acetabular components and 3 per cent (two hips) for the femoral components. In addition, 2 per cent (one) of the acetabular components and 5 per cent (three) of the femoral components demonstrated radiographic evidence of loosening. In the forty-three patients (forty-nine hips) who were alive at an average of seventy-four months (range, sixty to ninety-five months) after the revision, none of the acetabular components and 2 per cent (one) of the femoral components were revised again for aseptic loosening. An additional 2 per cent (one) of the acetabular components and 6 per cent (three) of the femoral components were radiographically loose. Ninety-eight per cent (forty-one) of the forty-two living patients (98 per cent [forty-seven] of the forty-eight hips) who had a clinical examination at least five years after the revision had increased function; 90 per cent (thirty-eight) of these patients (forty-four [92 per cent] of the hips) were satisfied with the result.The group that had a hybrid revision was compared with a group of seventy patients (seventy-four hips) who had had a revision total hip arthroplasty with use of contemporary cementing techniques for both components. These revisions had been performed by the same surgeon, before he performed the hybrid revisions, and the prevalence of repeat revision of the acetabular component was 7 per cent (five hips) and that of the femoral component was 4 per cent (three hips). In addition, 16 per cent (twelve) of the acetabular components and 3 per cent (two) of the femoral components were radiographically loose. The comparison group was not a consecutive series, as only the patients who had had radiographs made five to eight years after the revision were evaluated. In the fifty-two such patients (fifty-six hips) who were alive at five years after the revision with cement (average duration of radiographic follow-up, seventy-seven months; range, sixty to ninety-nine months), 9 per cent (five) of the acetabular components and 5 per cent (three) of the femoral components were revised again for aseptic loosening. An additional 21 per cent (twelve) of the acetabular components and 4 per cent (two) of the femoral components were radiographically loose.The results of the present study demonstrated a significant improvement (p = 0.0001) in the survival of the acetabular component of so-called hybrid revision total hip arthroplasties compared with that of revision total hip arthroplasties with cement performed by the same surgeon and followed for a comparable period.
The increasing use of so-called hybrid fixation (insertion of the acetabular component without cement and the femoral component with cement) in primary total hip arthroplasty has been based on several observations. These include the long-term problems associated with fixation of the acetabular component with cement14,36,44,46, the durable long-term results reported for fixation of the femoral component with cement3,4,36,44,46, the favorable mid-term results reported with well designed acetabular components inserted without cement42,43, and the initial encouraging results reported with use of hybrid fixation in primary total hip arthroplasty32,35,42.
Although the initial reports of fixation of the femoral component with cement in revision operations were not promising, those studies were based on the results of operations that were performed by surgeons who were early in the so-called learning curve and that were done with hand-packing of the cement2,7,25,26,39,40. Fixation of the femoral component with cement in revision operations has substantially improved with use of cement delivery systems, pressurization techniques, and experience13,24,33,41. However, even with the use of newer techniques for the application of cement, fixation of the acetabular component with cement in revision operations has proved less durable than such fixation of the femoral component in long-term studies13,24. In 1986, the senior one of us (R. C. J.) had performed hybrid fixation in primary total hip arthroplasties for two years. In addition, during revisions of total hip replacements that had been inserted with cement, he had observed excellent fixation of the femoral component but a higher prevalence of loosening of the acetabular component. Therefore, he stopped fixing both components with cement and began using hybrid fixation when both components were being revised.
The purpose of the present study was to evaluate the initial experience of one surgeon (R. C. J.) with hybrid revision total hip arthroplasty in one series of patients and to compare the results with those of revision total hip arthroplasty performed with contemporary cementing techniques by the same surgeon in another series of patients with the same duration of follow-up (five to eight years). Specifically, the study was designed to determine if the results of revision could be improved with use of an acetabular component inserted without cement and a femoral component inserted with cement.
*Although none of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received, but are directed solely to a research fund, foundation, educational institution, or other non-profit organization with which one or more of the authors is associated. No funds were received in support of this study.
†Department of Orthopaedic Surgery, The University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242.
‡6001 West Town Parkway, West Des Moines, Iowa 50266.
Between January 22, 1986, and November 17, 1988, sixty-one consecutive hybrid revision total hip arthroplasties were done by the senior one of us (R. C. J.) in fifty-five patients at Iowa Methodist Hospital in Des Moines, Iowa. Both components were revised in all of the patients. A Harris-Galante porous-coated hemispherical acetabular cup (Zimmer, Warsaw, Indiana) was inserted without cement and an Iowa femoral component (Zimmer) was inserted with cement in all of the revisions. The criterion for inclusion in the study was a revision of both components because of mechanical failure of a total hip replacement that had been inserted with cement. Patients who had had a conversion of a surface-replacement arthroplasty or a bipolar hemiarthroplasty to a total hip arthroplasty were excluded. Any patient in whom only one component had been revised was also excluded. There were no revisions for the failure of replacements that had been inserted without cement during the period of the study.
No patients were lost to follow-up. The study population included thirty-one men (56 per cent) and twenty-four women (44 per cent) who had an average age at revision of sixty-eight years (range, thirty-nine to eighty-nine years). Thirty-one operations (51 per cent) were performed on the right hip and thirty (49 per cent), on the left hip. The average height of the patients was 168 centimeters (range, 150 to 185 centimeters), and the average weight was eighty kilograms (range, forty to 109 kilograms). The diagnosis at the time of the initial arthroplasty was primary osteoarthrosis in seventeen hips (28 per cent), congenital dysplasia in ten (16 per cent), fracture of the femoral neck or the acetabulum in nine (15 per cent), avascular necrosis in five (8 per cent), rheumatoid arthritis in two (3 per cent), previous infection in two (3 per cent), Legg-Calvé-Perthes disease in one (2 per cent), slipped capital femoral epiphysis in one (2 per cent), and unknown in fourteen (23 per cent).
The reason for the revision was aseptic loosening in fifty-six hips (92 per cent), fracture of the stem in three (5 per cent), and recurrent dislocation in two (3 per cent). The hybrid revision was the first revision in forty-nine hips, the second in ten hips, and the third in two hips.
Forty-three patients (forty-nine hips) had been followed radiographically five to eight years after the procedure. Twelve patients had died, from causes unrelated to the operation on the hip, less than five years after the revision. One of the forty-three patients had not been followed clinically for at least five years. Therefore, the clinical results are reported for forty-two patients (forty-eight hips). Thirty-one patients (thirty-six hips; 75 per cent) who were followed clinically for at least five years returned for the examination, and eleven patients (twelve hips; 25 per cent) were interviewed by telephone. Relatives of all of the deceased patients were interviewed by telephone, but the information obtained was not included in the clinical results as the accuracy could not be confirmed. It was useful, however, for documenting complications and for determining whether the patient had lived at home, in an apartment, or in a care facility. The clinical examinations and interviews were conducted for all of the patients by one of us (K. L. W.), with use of a questionnaire with standard terminology and selected questions from an additional questionnaire22,23. The average age of the twenty-three men and twenty women who were living at least five years after the revision had been sixty-six years (range, thirty-nine to eighty-four years) at the time of the revision. Twenty-three operations were performed on the right hip and twenty-six, on the left hip. The average duration of follow-up for the living patients was seventy-four months (range, sixty to ninety-five months). At the most recent follow-up examination, it was determined whether the patient had class-A, B, or C involvement, according to the criteria of Charnley8; the clinical results were recorded; and the function of the patient was compared with the status before the revision (when both were known).
A group of patients who had had a revision total hip arthroplasty with cement performed between 1977 and 1983 by the same one of us (R. C. J.) was used for comparison. This was not a matched control group, but it presented the unique opportunity to study the results of two different operative techniques performed by the same surgeon. The operating room and the approach were the same for the two groups. Seventy-nine patients (eighty-three hips) had a revision with cement because of mechanical loosening of a total hip replacement. Nine patients who had not been followed radiographically in the five to eight-year follow-up period were excluded from the study. Seventy patients (seventy-four hips) formed the basis of this comparison group. Eighteen patients died less than five years after the revision, leaving fifty-two patients (fifty-six hips) who had had a five to eight-year radiographic evaluation. At the time of the revision, the twenty men and thirty-two women had an average age of sixty years (range, twenty-three to seventy-nine years), compared with sixty-six years for the patients who were alive at least five years after a hybrid procedure. Thirty-three operations (59 per cent) were performed on the right hip and twenty-three (41 per cent), on the left hip. The average duration of radiographic follow-up was seventy-seven months (range, sixty to ninety-nine months).
The radiographs that had been made for all of the patients in both groups before the revision were evaluated for osseous deficiencies of the acetabulum and femur, according to a modification of the system developed by The American Academy of Orthopaedic Surgeons9,10. The location of the segmental, cavitary, or combined defects was measured in centimeters on both the acetabular and the femoral side. (Deficiencies were recorded if they were two centimeters or larger.) In addition, we amplified the system by classifying the femoral defects as grade 1 (endosteal or cortical, in the proximal portion of the femoral neck), grade 2 (endosteal, extending to or distal to the tip of the prosthesis), or grade 3 (cortical, extending to or distal to the tip of the prosthesis). Radiographs made before the revision also were assessed for acetabular and femoral osteolysis.
The radiographs made before the hybrid revision total hip arthroplasties revealed an osseous deficiency that was two centimeters or larger (Table I) in thirty-four acetabula (56 per cent) and one that was smaller than two centimeters in twenty-seven (44 per cent). Ten acetabula (16 per cent) had a superior cavitary defect, six (10 per cent) had a medial cavitary defect, seven (11 per cent) had superior and medial cavitary defects, seven (11 per cent) had a superior segmental defect, three (5 per cent) had a medial segmental defect, and one (2 per cent) had diffuse cavitary and segmental defects. Twenty-four femora (39 per cent) had an osseous deficiency that was two centimeters or larger (Table I), and thirty-seven (61 per cent) had a deficiency that was smaller than two centimeters. Fifteen femora (25 per cent) had a cavitary defect, and nine (15 per cent) had a segmental defect. The deficiency was grade 1 in six femora (10 per cent), grade 2 in fifteen (25 per cent), and grade 3 in three (5 per cent). Ten hips (16 per cent) had osteolysis of the acetabulum, and nineteen hips (31 per cent) had osteolysis of the femur.
Over-all, the group that had a revision total hip arthroplasty with cement had fewer osseous deficiencies noted before the revision than did the group that had a hybrid revision. (It should be noted that data regarding osseous deficiencies were not available for the eighteen patients [eighteen hips] who died less than five years after the revision of both components with cement.) An osseous deficiency that was two centimeters or larger was seen in twenty-five (45 per cent) of the fifty-six acetabula, and a deficiency that was smaller than two centimeters was seen in thirty-one (55 per cent). The defect was described as superior segmental in fifteen acetabula (27 per cent), medial cavitary in seven (13 per cent), combined in two (4 per cent), and superior cavitary in one (2 per cent). Before the revision, only nine femora (16 per cent) had an osseous deficiency that was two centimeters or larger, and forty-seven (84 per cent) had a deficiency that was smaller than two centimeters. The defect was cavitary in seven femora (13 per cent) and segmental in two (4 per cent). It was grade 1 in two femora (4 per cent), grade 2 in five (9 per cent), and grade 3 in two (4 per cent).
All of the revision operations were performed by the senior one of us in an operating suite with laminar airflow and the use of body-exhaust systems. All patients were placed in the lateral decubitus position, and a transtrochanteric approach was used. No preoperative aspirations of the hip were performed. Preoperative antibiotic prophylaxis was given with intravenous administration of cephalosporin. For each patient, four sets of intraoperative tissue specimens were sent for culture and a section of tissue obtained just proximal to the proximal portion of the femoral neck was sent for pathological examination. None of the components were considered septically loose on the basis of these evaluations. Cement was removed with hand tools and without the use of fluoroscopy or cortical windows. The soft-tissue membrane at the bone-cement interface was thoroughly debrided, and the neocortex was removed with high-speed burrs and, when necessary, with reamers. A complete capsulectomy was performed.
The Harris-Galante acetabular components ranged in size from forty-six to seventy millimeters (average, sixty-one millimeters) and were placed with use of on-line reaming (that is, the component selected was the same size as the last reamer used to prepare the acetabulum). Supplemental fixation of the component was obtained with two or three 5.1-millimeter titanium screws. The cup was placed in a so-called high hip center, in order to be in contact with living host bone, when there was a large superior osseous defect. No structural bone graft was used, although morselized autogenous bone graft from the last acetabular reaming was occasionally needed to fill small defects in the acetabulum. Contemporary cementing techniques, including pulsatile lavage of the femoral canal, a distal cement plug, injection of cement with a pressurizing gun, and reduction of the porosity of the cement by centrifugation, were used1,6,37,48. A precoat of polymethylmethacrylate was applied by the manufacturer to the proximal portion of the Iowa femoral component (Zimmer) to enhance the prosthesis-cement bond. Simplex-P cement (Howmedica, Rutherford, New Jersey) impregnated with antibiotic powder (cephalosporin with or without aminoglycoside) was used in all of the revisions. A long-stemmed femoral component (200 millimeters or longer) was used in twenty hips (33 per cent) to bypass all cortical defects, regardless of size. Otherwise, the standard 140-millimeter-long component was utilized. In most of the patients who had a cortical defect, the long-stemmed component was used instead of bone-grafting. A twenty-eight-millimeter femoral head was used in all of the patients.
Postoperatively, the patients wore a Thomas splint in traction for six days and then wore a spica cast-brace for two months. The patients were managed with protected weight-bearing with use of double supports for two months, followed by use of a cane until they were comfortable without support. After the operation, cephalosporin was administered intravenously until the results of the final cultures were reported, and it was administered orally for six weeks after discharge from the hospital. As prophylaxis against deep venous thrombosis, low-molecular-weight dextran was administered intravenously to all of the patients on the first, second, and third postoperative days and then every other day until discharge. They also wore support hose and received enteric-coated aspirin daily for two months as prophylaxis.
For the femoral revision, a Charnley component (Thackray, Leeds, England) was removed from seventeen hips (28 per cent); a Müller component (Howmedica or Zimmer), from twelve (20 per cent); an Iowa component (Zimmer), from eleven (18 per cent); a trapezoidal-28 component (Zimmer), from four (7 per cent); a CDH-type stem, from three (5 per cent); a Bechtol component (Richards, Memphis, Tennessee), from two (3 per cent); an Aufranc-Turner component (Howmedica), from two (3 per cent); and various other or unknown components, from ten (16 per cent). Thirty-five (57 per cent) of the revised hips had had a previous trochanteric osteotomy.
The most recent available radiographs of the pelvis (anteroposterior radiographs showing the tip of the femoral component and additional radiographs needed to visualize the long-stemmed components), made an average of seventy-four months after the hybrid revision, were examined. These radiographs were compared with the initial postoperative radiograph and with radiographs made at one to two-year intervals. Judet radiographs made at the most recent follow-up examination were available for thirty-eight hips and were used for additional evaluation of acetabular radiolucent lines. Three orthopaedic surgeons (J. J. C., D. D. G., and K. L. W.) simultaneously studied the radiographs that had been made before the revision, postoperatively, and during the follow-up examinations for all of the patients, and they came to an agreement on the findings.
The cementing technique was graded, according to the criteria of Barrack et al.4, on the postoperative radiograph. Grade A is defined as complete filling of the medullary cavity by cement, including two centimeters distal to the tip; grade B, slight radiolucency at the bone-cement interface; grade C, radiolucency involving more than 50 per cent but less than 100 per cent of the bone-cement interface; and grade D, radiolucency involving 100 per cent of the bone-cement interface on any radiograph.
All radiographic measurements were adjusted for magnification by comparing the actual width with the measured size of the femoral head on each radiograph, according to the technique of Livermore et al.29.
The acetabulum was divided into three zones, as described by DeLee and Charnley11. The radiographs were evaluated, with use of the technique described by Livermore et al.29, for placement of the hip center in relation to the interteardrop line, radiolucency at the metal-bone interface, migration of the component, breakage of the screws, osteolysis, and linear acetabular wear. Migration of the cup was defined as more than five millimeters of variation in the vertical distance between the center of the cup and the line joining the teardrops or the horizontal distance between the center of the cup and a vertical line through the teardrop34. For the acetabular components in the comparison group, definite loosening was defined as migration of the component or the presence of any new fracture in the cement mantle; probable loosening, as a circumferential radiolucent line around 100 per cent of the component at the bone-cement interface; and possible loosening, as a radiolucent line around 50 to 99 per cent of the component at the bone-cement interface.
The seven zones on the anteroposterior radiographs, as defined by Gruen et al.16, were used to localize radiolucency and osteolysis around the femoral component. Subsidence of the femoral component was defined as an increase of at least five millimeters in the vertical distance from the tip of the stem to the drill-hole for the trochanteric reattachment wire in the lateral cortex, according to the method of Loudon and Charnley30. Debonding was noted as separation of the stem from the surrounding cement, usually in zone 1 of Gruen et al.
Radiographic loosening of the femoral component was classified according to the system of Harris and McGann18. Definite loosening was defined as migration of the component or cement, fracture of the cement, or the appearance of a radiolucent line at the cement-prosthesis interface that had not been present on the postoperative radiograph. Probable loosening was defined as a continuous radiolucent line at the bone-cement interface without migration of the component, and possible loosening was defined as an incomplete radiolucent line involving 50 to 99 per cent of the bone-cement interface.
The reattached trochanter was noted to be united, non-united, or migrated. Heterotopic ossification was graded according to the system of Brooker et al.5.
For both groups, the Kaplan-Meier method was used to calculate the probability of retention of the components from the time of the index revision to one of four end points: repeat revision for aseptic loosening of the acetabular component, repeat revision for aseptic loosening of the femoral component, repeat revision for aseptic loosening or radiographic evidence of definite or probable loosening of the acetabular component, or repeat revision for aseptic loosening or radiographic evidence of definite or probable loosening of the femoral component. The Fisher exact two-tailed test was used for all other comparisons.
Hybrid Revision
The clinical results of the hybrid revisions were available for forty-two patients (forty-eight hips) who were living and had clinical follow-up at the minimum duration of five years (maximum, eight years). The function of the patient at the latest evaluation was compared with that before the revision (when both were known). At the latest follow-up examination, fourteen patients had Charnley class-A involvement; seven, class-B; and twenty-one, class-C. Two patients (two hips; 4 per cent) performed heavy manual labor, frequently lifting as much as forty-five kilograms; eleven patients (thirteen hips; 27 per cent) engaged in moderate manual labor, lifting as much as twenty-three kilograms or walking more than five kilometers daily; fourteen patients (fifteen hips; 31 per cent) performed light labor, such as strenuous house-cleaning, yard work, or assembly-line duties; fourteen patients (seventeen hips; 35 per cent) considered themselves sedentary, performing light house-cleaning or working at a desk; and one patient (one hip; 2 per cent) was sedentary. The sedentary patient was an eighty-four-year-old woman who was debilitated by rheumatoid arthritis involving multiple joints. Before the revision, only ten patients (eleven hips; 23 per cent) could perform light labor. The level of activity improved in twenty-eight patients (thirty-two hips; 67 per cent) and stayed the same in the remaining fourteen patients (sixteen hips; 33 per cent).
In general, the living situation of the patients did not change after the revision operation on the hip. Of the patients who were alive at the latest follow-up examination, six patients (eight hips; 17 per cent) lived alone and maintained a house, twenty-nine patients (thirty-three hips; 69 per cent) lived in a house with a spouse or family, five patients (five hips; 10 per cent) maintained an apartment, one patient (one hip; 2 per cent) lived in a house or an apartment with assistance from a part-time caretaker, and one patient (one hip; 2 per cent) lived in a house with assistance from a full-time caretaker. Before the revision, seven patients (nine hips; 19 per cent) had maintained a house alone, thirty patients (thirty-four hips; 71 per cent) had lived in a house with a spouse or family, three patients (three hips; 6 per cent) had maintained an apartment, and two patients (two hips; 4 per cent) had lived in a house or an apartment with assistance from a part-time caretaker.
The rating for pain before the revision was considered severe for twenty-eight hips (58 per cent), moderate for nineteen (40 per cent), and mild for one (2 per cent). At the latest follow-up evaluation, thirty hips (63 per cent) were pain-free; eleven (23 per cent) were only occasionally painful, necessitating no change in activity; and seven (15 per cent) were moderately painful, causing the patient to modify his or her activity. Over-all, the operation had decreased the pain, and the need for analgesics, in fifty-six (92 per cent) of sixty-one hips.
At the latest follow-up examination, twenty-nine patients (thirty-three hips; 69 per cent) could walk for an unlimited time; six patients (seven hips; 15 per cent) could walk for thirty-one to sixty minutes; four patients (four hips; 8 per cent), for eleven to thirty minutes; and three patients (four hips; 8 per cent), for two to ten minutes. Before the revision, eighteen patients (nineteen hips; 40 per cent) had used no support, two patients (two hips; 4 per cent) had used a cane occasionally, and twenty-two patients (twenty-seven hips; 56 per cent) had needed full-time support. At the most recent follow-up examination, twenty-four patients (twenty-seven hips; 56 per cent) needed no support, eight patients (nine hips; 19 per cent) needed a cane occasionally, and ten patients (twelve hips; 25 per cent) needed full-time support. Thirty-one patients (thirty-six hips; 75 per cent) could put on their shoes and socks without difficulty; ten patients (eleven hips; 23 per cent), with slight difficulty; and one patient (one hip; 2 per cent) was unable to complete this activity. Twenty-four patients (twenty-seven hips; 56 per cent) could walk up stairs foot over foot with or without the use of a banister, fifteen patients (seventeen hips; 35 per cent) needed to put two feet on each stair, two patients (three hips; 6 per cent) needed assistance, and one patient (one hip; 2 per cent) was unable to ascend stairs. Twenty patients (twenty-two hips; 46 per cent) could stand up from a chair without using their arms, twenty-one patients (twenty-five hips; 52 per cent) needed some support, and one patient (one hip; 2 per cent) was unable to rise from a chair. Thirty-two patients (thirty-six hips; 75 per cent) could pick up an object from the floor without difficulty, six patients (six hips; 13 per cent) had difficulty, three patients (five hips; 10 per cent) needed support while picking up the object, and one patient (one hip; 2 per cent) was unable to pick up the object. Thirty-three patients (thirty-seven hips; 77 per cent) had no limit on how much they could carry (compared with the capacity of normal individuals), and nine patients (eleven hips; 23 per cent) noted a limit.
The gait of the thirty-one patients (thirty-six hips) who returned to the clinic for an examination was evaluated. All of these patients had walked with a limp before the revision. At that time, the limp associated with thirteen hips (36 per cent) could be detected only by a trained observer. The patients and their families had noticed the limp associated with fifteen hips (42 per cent). The limp had severely altered the gait associated with seven hips (19 per cent), and one patient (one hip; 3 per cent) was unable to walk. At the most recent follow-up evaluation, twenty hips (56 per cent) were not associated with a noticeable limp, ten (28 per cent) were associated with a slight limp, four (11 per cent) were associated with a moderate limp, and two (6 per cent) were associated with a severe limp.
Forty-one patients (forty-seven hips; 98 per cent) who were followed for at least five years stated that the operation had increased the function, and thirty-eight patients (forty-four hips; 92 per cent) were satisfied with the result. Four patients (four hips; 8 per cent) were dissatisfied with the result. One was a seventy-seven-year-old man who had recurrent dislocations of the hip but who did not have radiographic loosening. Another was a seventy-eight-year-old man who had had a repeat revision of the femoral stem at six months for recurrent dislocation and who had radiographic loosening at the most recent follow-up examination. The third dissatisfied patient was a seventy-six-year-old woman who had soreness in the lateral part of the buttocks but no evidence of radiographic loosening. The fourth patient was the eighty-four-year-old woman who had severe rheumatoid arthritis and was not satisfied with her condition in general.
Dislocation was the most common complication, occurring in ten (16 per cent) of the sixty-one hips. Recurrent dislocation necessitated a reoperation in five hips (8 per cent), although the original acetabular component was not revised in any hip. Trochanteric bursitis was noted in six hips (10 per cent). There were no superficial or deep infections and no clinically evident nerve palsies. Seven weeks after the hybrid revision, a deep venous thrombosis developed in one patient (one hip; 2 per cent) who had a history of recurrent deep venous thrombosis. She was successfully managed with intravenous administration of heparin followed by Coumadin (warfarin). None of the patients had clinically evident pulmonary emboli.
With the numbers available, the presence of either an acetabular or a femoral osseous deficiency preoperatively was not associated with loosening of the acetabular component (p = 1.0), loosening of the femoral component (p = 0.65), or repeat revision (p = 1.0). Acetabular radiolucency at the latest follow-up evaluation was associated with a preoperative acetabular osseous deficiency (p = 0.02).
The femoral cementing technique was grade A in seventeen (28 per cent) of the sixty-one hips, grade B in twenty-eight hips (46 per cent), and grade C in sixteen hips (26 per cent)4. There were no hips with grade-D technique. With the numbers available, the grade of the cementing technique was not associated with loosening of the component (p = 0.43) or repeat revision (p = 0.07). More than one centimeter of proximal-medial cement was present in forty-three hips (70 per cent) and at least 0.5 centimeter of distal-lateral cement was present in thirty-three hips (54 per cent). A circumferential mantle of cement was present in fifty-one hips (84 per cent). The femoral alignment was neutral in forty-two hips (69 per cent), valgus in eight (13 per cent), and varus in eleven (18 per cent).
Five to eight years after the sixty-one hybrid revisions, none of the acetabular components and two (3 per cent) of the femoral components had had a repeat revision for aseptic loosening (Table I). The two repeat revisions were done at fourteen and thirty-eight months. In addition, one (2 per cent) of the acetabular components and three (5 per cent) of the femoral components demonstrated radiographic evidence of definite or probable loosening. There was no septic loosening. The one loose acetabular component had migrated within the first six months after revision. However, at the most recent follow-up examination, the component was found to have stabilized and a repeat revision was not needed. There were no broken screws. Four femoral components (including the two that had a repeat revision) were definitely loose, one was probably loose, and two were possibly loose. In the forty-three patients (forty-nine hips) who were alive at the time of the five to eight-year follow-up examination, none of the acetabular components and one (2 per cent) of the femoral components needed a repeat revision for aseptic loosening (Table I). In addition, one (2 per cent) of the acetabular components and three (6 per cent) of the femoral components had radiographic evidence of loosening. The two femoral components that had a repeat revision for aseptic loosening were radiographically stable at the most recent follow-up examination at one and 5.5 years.
The probability of retention eight years after the hybrid revision was 100 per cent for the acetabular component and 96.6 ± 2.4 per cent (probability and 95 per cent confidence interval) for the femoral component with use of repeat revision for aseptic loosening as the end point. The probability of survival at eight years was 98.4 ± 1.6 per cent for the acetabular component and 81.2 ± 9.6 per cent for the femoral component with use of repeat revision for aseptic loosening or radiographic evidence of definite or probable loosening as the end point. The probability of survival of the femoral component at five years was 96.2 ± 2.6 per cent with use of repeat revision for aseptic loosening or radiographic evidence of definite or probable loosening as the end point. The confidence interval increased suddenly at eight years for loosening of the femoral component because few hips were followed for this time period.
The average vertical height from the interteardrop line to the reconstructed hip center was 25.0 millimeters (range, 13.6 to 46.7 millimeters). The hip center on the side that was not operated on was an average of 12.7 millimeters proximal to the interteardrop line, which is consistent with the measurements in other studies27,47. With use of a height of thirty millimeters or more proximal to the interteardrop line as the criterion for a high hip center, there were fourteen high hip centers (23 per cent). When thirty-five millimeters or more was the criterion, there were six high hip centers (10 per cent). With the numbers available, neither a hip center at thirty millimeters nor one at thirty-five millimeters was associated with acetabular radiolucency (p = 0.21 and 0.67, respectively), loosening of the femoral component (p = 0.32 and 0.42, respectively), or repeat revision of the femoral component (p = 0.41 and 0.19, respectively). A high hip center was not associated with an increased risk of dislocation (p = 0.19).
Evaluation of the results for the twenty hips with a long-stemmed femoral component revealed that, with the numbers available, use of this device was not associated with dislocation (p = 0.47), recurrent dislocation (p = 1.0), or loosening of the acetabular component (p = 1.0). It was associated with loosening of the femoral component (p = 0.04).
Judet radiographs were made for thirty-eight hips (62 per cent), and they were helpful for detecting acetabular radiolucency that had not been seen on standard radiographs of nine (24 per cent) of these hips. At the latest follow-up examination, acetabular radiolucency was seen in zone 1 in twenty-one hips, zone 2 in twenty-four hips, and zone 3 in thirty-three hips. Progressive radiolucency was seen in twenty-one hips (43 per cent). Only one hip had complete acetabular radiolucency. No acetabular osteolysis was observed, but femoral osteolysis was seen in seven hips (14 per cent) at the latest follow-up examination. The average rate of linear wear was 0.08 millimeter (range, 0.00 to 0.25 millimeter) per year.
Heterotopic ossification was absent in forty-six (94 per cent) of the hips with radiographic follow-up at five to eight years. It was graded as class I in two hips (4 per cent) and as class II in one hip (2 per cent), according to the system of Brooker et al.5. The greater trochanter was united in forty-four (72 per cent) of all sixty-one hips, non-united in ten (16 per cent), and non-united and migrated in seven (11 per cent).
Revision Total Hip Arthroplasty with Cement
The most recent radiographs of the fifty-two patients (fifty-six hips) who were alive and had been followed for five to eight years after a revision total hip arthroplasty with cement were evaluated for the grade of the cementing technique, osteolysis, and loosening. The cementing technique was grade A in thirty-eight (68 per cent) of the fifty-six hips, grade B in seventeen (30 per cent), and grade C in one (2 per cent)4. Acetabular osteolysis was seen in six (11 per cent) of the hips and femoral osteolysis, in thirteen (23 per cent).
When all seventy-four hips that had had a revision with cement were included, the prevalence of repeat revision of the acetabular component for aseptic loosening was 7 per cent (five hips) and that of repeat revision of the femoral component was 4 per cent (three hips). The time to repeat revision averaged eighty-nine months (range, eighty-two to ninety-four months) for the acetabular components and eighty-six months (range, eighty-two to eighty-nine months) for the femoral components. In addition, twelve (16 per cent) of the acetabular components and two (3 per cent) of the femoral components had radiographic evidence of loosening. Of the fifty-six hips in the fifty-two patients who were living five to eight years after the revision total hip arthroplasty with cement, five (9 per cent) had repeat revision of the acetabular component for aseptic loosening and three (5 per cent) had such a revision of the femoral component. An additional twelve (21 per cent) of the acetabular components and two (4 per cent) of the femoral components had radiographic evidence of loosening. The prevalence of loosening of the acetabular component was significantly different from that for the patients who had had the hybrid revision and were living at least five years after the procedure (p = 0.0001, Fisher exact test) (Table I).
The probability of retention eight years after the revision arthroplasty with cement was 59.8 ± 16.3 per cent for the acetabular component and 83.1 ± 9.2 per cent for the femoral component with use of repeat revision for aseptic loosening as the end point. The probability of retention at eight years was 36.4 ± 12.1 per cent for the acetabular component and 77.2 ± 10.7 per cent for the femoral component with use of repeat revision for aseptic loosening or radiographic evidence of definite or probable loosening as the end point.
The reasons for the use of hybrid fixation in revision operations have been similar to those proposed for its use in primary arthroplasty. First, the results of fixation of the femoral component with cement in revision operations were found to improve after surgeons began debriding the soft-tissue membrane and the neocortex in the medullary canal, causing the cement to interdigitate into bone more effectively, and after they began using a cement-gun delivery system that plugged the distal part of the canal. (This cementing technique can be done with a cement plug only when fixation extends distal to the isthmus.) Second, it was observed that fixation of the acetabular component with cement continued to fail in revision operations even when surgeons had experience with the procedure and newer insertion techniques were used.
The strength of the present study is the opportunity that it affords for comparison of the results of two techniques of revision operations on the hip (hybrid fixation and fixation with use of contemporary cementing techniques), performed by one surgeon in two groups of patients with comparable durations of follow-up. In both series, a transtrochanteric approach to the hip was used, all neocortex and soft-tissue membrane were thoroughly removed, a distal cement plug was inserted, and antibiotic-impregnated Simplex-P cement (Howmedica) was used. In the series that had fixation of the acetabular component with cement, the cement was pressurized with use of a rubber plunger. Other than fixation of the acetabular component without cement, the only changes in the series that had a hybrid revision were the reduction of the porosity of the cement by centrifugation and the use of a polymethylmethacrylate-precoated Iowa femoral component rather than a non-precoated Iowa or Charnley component, which were used in the series that had revision of the acetabular component with cement.
The series of revisions with cementing of both components began in 1977, after the senior one of us (R. C. J.) had had four to five years of experience with revision hip operations. Five to eight-year radiographs were available for this series because most of the patients had had regular follow-up evaluations and because the results were reviewed for an unpublished report at a minimum of five years. Revision of both the acetabular and the femoral component was necessary for inclusion in either series.
At the five to eight-year follow-up evaluation of the results of the hybrid revisions, none of the acetabular components had had a revision for loosening and only one acetabular component (2 per cent), which initially had migrated but had remained stable for the ensuing six years, was loose. Only two femoral components (3 per cent) had had a repeat revision for aseptic loosening over-all, and only one (2 per cent) of the femoral components in the patients who were alive at least five years after the procedure had had such a revision. An additional three femoral components (5 per cent over-all and 6 per cent of those in the living patients) demonstrated probable or definite radiographic loosening.
By comparison, five to eight years after fixation of both components with cement, five acetabular components (7 per cent over-all and 9 per cent of those in the living patients) had had a repeat revision for aseptic loosening and another twelve (16 per cent over-all and 21 per cent of those in the living patients) demonstrated definite or probable loosening. Three femoral components (4 per cent over-all and 5 per cent of those in the living patients) had a repeat revision for aseptic loosening, and an additional two (3 per cent over-all and 4 per cent of those in the living patients) had definite or probable loosening.
The results of fixation of the acetabular component without cement were significantly better than those for fixation of the acetabular component with cement during a comparable period of follow-up (p = 0.0001). However, with the numbers available, the results for fixation of the femoral component were not significantly different (p = 0.62) even though the quality of the bone and the cementing technique in the series that had fixation of both components with cement were better than those in the series that had a hybrid revision.
After the hybrid revisions, no hip had septic loosening, which may be attributed to the use of cement impregnated with antibiotics for fixation of the femoral component. This finding corroborates the results reported by Lynch et al.31, who demonstrated a reduction in the rate of infection from 3 per cent (three of 106 hips) when cement without antibiotic impregnation had been used in a revision operation to less than 1 per cent (one of 192 hips) when cement impregnated with antibiotics had been used.
The excellent results achieved with fixation of the acetabular components without cement in the present study corroborate those reported with use of the Harris-Galante I component and supplemental fixation with screws in the acetabular dome27,38,47. In a study of 129 hips by Padgett et al.38, a study of 140 hips by Tanzer et al.47, and a study of sixty hips by Lachiewicz and Hussamy27, use of the Harris-Galante I component in a revision operation was followed by a prevalence of loosening of the acetabular component of 0 per cent at 3.7 years, 1 per cent at 3.5 years, and 0 per cent at five years, respectively.
The revision operations in the present report differed from those in the other reports27,38,47 in that no structural allografts were used. Instead, when an osseous deficiency of the acetabulum would not allow a large hemispherical component of as many as seventy millimeters in diameter to be used, which was usually when the medial-lateral dimension of the acetabulum was shallow (Figs. 1A, 1-B, and 1-C), or if a structural allograft was needed in the acetabulum to position the hip center at its anatomical location (Figs. 2-A, 2-B, and 2-C), the acetabular component was positioned on viable bone at a high hip center. As a result, it was necessary to use a femoral component with a longer neck in some hips and to pay particular attention to preventing impingement of the femur on the ischium. Placement at a high hip center was necessary in fourteen hips, and those hips did not have a higher rate of loosening or dislocation at five to eight years. These findings agree with those of Schutzer and Harris45, who evaluated the results of fifty-six procedures (forty-nine revisions and seven primary hip arthroplasties) in fifty-two patients and found no definite loosening and a rate of dislocation of 6 per cent. The present study provides additional evidence that placement of a revision acetabular component at a high hip center is not associated with loosening.
The substantial improvement in the results of femoral revision with use of contemporary cementing techniques in the present study corroborate the findings of Rubash and Harris41 as well as those of Estok and Harris13. In the former study41, forty-three hips in forty-one patients were revised with contemporary cementing techniques, including the use of pulsatile lavage of the femoral canal, a distal cement plug, and injection of cement with a pressurizing gun. At an average of 6.2 years, one (2 per cent) of the forty-three femoral components had had a repeat revision and five (12 per cent) were radiographically loose. In the same series, thirty-eight hips in thirty-six patients were evaluated at an average of 11.7 years. The prevalence of repeat revision of the femoral component was 11 per cent (four of thirty-eight) and an additional 11 per cent were radiographically loose. After the hybrid revisions in the present study, we found a prevalence of repeat revision for aseptic loosening of 3 per cent over-all (two of sixty-one) and an additional 5 per cent (three) had evidence of radiographic loosening. Our results are superior to those reported for fixation without cement of proximally coated femoral components when repeat revision or subsidence of the component was used as the end point for failure12,17,19,20,21. We are aware of only one study in which fixation of femoral components without cement had comparable results after a similar duration of follow-up28. Lawrence et al.28 described the fixation of extensively porous-coated femoral components without cement in eighty-three hips, and they reported an 8 per cent prevalence of repeat revision for loosening or fracture of the component at a minimum of five years (average, nine years).
On the basis of the over-all results in the present study, hybrid fixation is used by the senior one of us in most revision hip arthroplasties. For patients who have extensive femoral osteolysis and osseous deficiency, the femoral construct is fixed with impaction grafting and cement, as described by Gie et al.15, and the acetabular component is fixed without cement. As this technique has been used by the senior one of us for only two years, a longer duration of follow-up is needed to determine the efficacy of the impaction-grafting approach.
NOTE: The authors thank Patricia Kratz for her time and effort in helping to complete this study.
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