JBJS | Clinical and Radiographic Outcomes of Total Hip Arthroplasty with Insertion of an Anatomically Designed Femoral Component without Cement for the Treatment of Primary Osteoarthritis. A Study with a Minimum of Six Years of Follow-up*

The Journal of Bone & Joint Surgery, Volume 81, Issue 2

Articles | February 01, 1999

Clinical and Radiographic Outcomes of Total Hip Arthroplasty with Insertion of an Anatomically Designed Femoral Component without Cement for the Treatment of Primary Osteoarthritis. A Study with a Minimum of Six Years of Follow-up*

ASHRAF A. RAGAB, M.D.†; MATTHEW J. KRAAY, M.D.†; VICTOR M. GOLDBERG, M.D.†, CLEVELAND, OHIO

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Investigation performed at the Department of Orthopaedics, University Hospitals of Cleveland, Case Western Reserve University, Cleveland

The Journal of Bone & Joint Surgery. 1999; 81:210-218

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Abstract

We evaluated the clinical and radiographic outcomes of 100 consecutive primary total hip arthroplasties in which a proximally coated anatomically designed femoral component was fixed without cement for the treatment of primary osteoarthritis. The minimum duration of follow-up was six years (average, 7.1 years). The eighty-eight patients who had the arthroplasties were followed prospectively with a standard clinical evaluation that involved use of the Harris hip score and a radiographic evaluation based on the criteria of the Hip Society. Bone ingrowth was evaluated with the method of Engh et al.The average age of the patients at the time of the operation was 62.6 years (range, thirty-nine to eighty-four years). Fifty-one patients were men and thirty-seven were women. The average preoperative Harris hip score was 48 points, with an average pain score of 15 points and an average function score of 26 points. Nonmechanical complications that necessitated a revision operation included one deep hematogenous infection, one late periprosthetic fracture, and a 0.5-inch (1.27-centimeter) limb-length discrepancy. At the time of the most recent follow-up, the average Harris hip score was 96 points, with an average pain score of 42 points and an average function score of 45 points. The prevalence of pain in the anterior part of the thigh was 5 percent (five hips). One patient had a revision of the femoral component because of aseptic loosening, and one had a revision of the acetabular component because of recurrent dislocations.Radiographic assessment revealed consistent evidence of proximal bone ingrowth. No complete radiolucent line was identified, except around the stem that had loosened. Twenty-seven femoral components were associated with slight pedestal formation. No osteolytic lesion of the femur was identified. Nonprogressive pelvic osteolysis was identified in four hips, but none of the lesions were more than two millimeters in diameter. None of the acetabular components migrated, and no radiolucent line of more than two millimeters in thickness was seen around any acetabular cup.The data from this study, in which the minimum duration of follow-up was six years, indicate that the anatomically designed prosthesis can provide good results, with low prevalences of pain in the thigh and loosening of the component, in younger, active patients.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Aseptic loosening of a cemented femoral component after a total hip arthroplasty is a potential cause of pain and loss of function, resulting in the subsequent need for a revision. Previous reports of femoral loosening in younger patients^12,14,19 led to the design of femoral components that are fixed without cement. Several reports have documented disappointing early clinical and radiographic results with early designs of total hip prostheses fixed without cement^{4,6-8,29,34,35}. However, these so-called first-generation stems did not always have a circumferential porous surface or a design that provided sufficient initial stability to allow bone ingrowth to occur. Of particular concern have been the frequent findings of pain in the anterior part of the thigh and limping after use of these early designs. The extent of bone growth into the porous surface, abnormal bone-remodeling due to stress-shielding, and bone resorption or osteolysis have also been unresolved issues.

Several factors contributing to these adverse effects, which may eventually result in failure of the total hip arthroplasty, include the selection of the patients and the materials and design of the implant^{2,12-14,20,23}. Probable underlying causes of aseptic loosening include excessive initial micromotion of the femoral component, which precludes bone ingrowth in the short term, and prosthetic materials and design that can result in adverse bone-remodeling in the long term²⁰. Large femoral components that completely fill the femoral canal have been proposed as a method of minimizing micromotion at the interface; however, large stiff stems have been shown to be associated with adverse bone-remodeling. Consequently, this may not be a long-term solution to the problem of fixation in total hip arthroplasty²⁰. Many designs have been studied in an attempt to minimize these adverse effects and thus to improve outcome^26,36,37,41. Although design concepts vary, they all must take into consideration the complex pattern of loading in the proximal part of the femur²⁰.

Many different methods for the evaluation of the clinical outcomes of total hip arthroplasty have been described^9,24,27,40. Clinical scoring systems based on the patient's perception of pain, function, and functional activities have been proposed^18,24,27,40. Radiographic evaluations have typically quantified radiolucent lines at the prosthetic interface; the fit, fill, and alignment of the implant; and the presence or absence of remodeling associated with stress-shielding and instability of the stem^{10,15,22,27,32}. Although there are other patient-directed outcome measures, these clinical and radiographic outcome measures provide the basis for a database with which to assess the results associated with a specific implant³¹.

The purpose of the present study was to assess the outcomes of a consecutive series of total hip arthroplasties in which an anatomically designed femoral component with a circumferential proximal coating and an acetabular component were both inserted without cement in patients who had primary osteoarthritis of the hip. The emphasis of the study was on the femoral component. The patients were followed prospectively for a minimum of six years, with use of a standardized clinical and radiographic scoring system.

*One or more 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. No funds were received in support of this study.

†Department of Orthopaedics, University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106.

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FIG1-A:: Fig. 1-A Anteroposterior (Fig. 1-A) and frog-leg lateral (Fig. 1-B) radiographs made seven years after the implantation of the anatomically designed femoral component. The Harris hip score²⁴ was 96 points.

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FIG1-B:: Fig. 1-B Anteroposterior (Fig. 1-A) and frog-leg lateral (Fig. 1-B) radiographs made seven years after the implantation of the anatomically designed femoral component. The Harris hip score²⁴ was 96 points.

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FIG2:: Fig. 2 Anteroposterior radiograph made six years after a bilateral total hip arthroplasty. The right femur demonstrates calcar-rounding and remodeling (arrow).

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FIG3:: Fig. 3 Anteroposterior radiograph of the hip of a patient who needed a revision eighteen months after the index operation because of aseptic loosening. The patient had severe pain in the thigh, subsidence of the femoral component, and extensive pedestal formation.

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

One hundred primary total hip arthroplasties with insertion of an anatomically designed stem (Figs. 1-A and 1-B) without cement were performed at our institution by the senior one of us (V. M. G.), between July 1988 and December 1991, in eighty-eight patients who had primary osteoarthritis. One patient died of unrelated causes, but the hip was functioning satisfactorily at the time of death and was included in the follow-up analysis. Ninety-seven stems were available for assessment by one of us (A. A. R.), who had not been involved with the operative procedure. Three hips that had been revised because of nonmechanical reasons (a hematogenous infection, a periprosthetic fracture, and a limb-length discrepancy) were excluded from the analysis. Failure of the hip prosthesis was defined as a revision for any mechanical complication. The average duration of follow-up was 7.1 years (range, 6.0 to 9.5 years).

The average age of the patients was 62.6 years (range, thirty-nine to eighty-four years) at the time of the index operation. The average weight of the patients was 84.4 kilograms (range, forty-five to 140 kilograms). Thirty-seven patients were women and fifty-one were men. The clinical indications for the use of the implant were a chronological age of less than seventy-five years or a life expectancy of approximately ten years according to the Metropolitan Life Insurance Company life-expectancy tables as well as a femur that was classified radiographically as type A or B according to the criteria of Dorr et al.¹¹. Finally, the selected intraoperative rasp corresponding to the implant to be inserted had to be torsionally stable as determined with use of a torque wrench by the surgeon, as will be described. If all of these criteria were not met, the stem was not used.

The procedure was performed in a laminar airflow operating room, and the surgeons wore body-exhaust isolation suits. Prophylactic antibiotics (cefazolin) were administered intravenously (one dose preoperatively and for forty-eight hours postoperatively). All patients received prophylactic anticoagulation with warfarin for five, six, or seven days; wore thromboembolic hose; and were managed with sequential compression devices.

All procedures were performed through a standard posterolateral approach and with a Ti-6Al-4V femoral component that is proximally and circumferentially coated with a commercially pure titanium fiber-metal porous surface (Anatomic; Zimmer, Warsaw, Indiana). The design features of the stem, which have been previously described, emphasize matching of the geometric and mechanical properties of the proximal part of the femur²⁰. The structural stiffness of the stem was optimized by use of a titanium-based material and distal fluting. The torsional stability of the implant was determined intraoperatively by applying a commercially available torque wrench to the rasp after full seating. The adequacy of the metaphyseal fit and fill and the stability of the rasp were determined by the absence of motion of the rasp under a torsional load of 180 inch-pounds (20.3 newton-meters).

The acetabulum was resurfaced with use of a modular component (Harris-Galante II; Zimmer), with a Ti-6Al-4V shell and a commercially pure titanium fiber-metal porous surface, that was fixed to the pelvis with 6.5-millimeter cancellous-bone screws and no cement. The polyethylene liners had an inner diameter of twenty-eight millimeters, and they ranged in thickness from 7.3 to 13.3 millimeters.

Clinical Evaluation

The clinical performance of the stem was assessed with use of the Harris hip score²⁴ preoperatively, at three and six months postoperatively, and then at yearly intervals. A Harris hip-rating of 90 points or more was considered excellent; one of 80 to 89 points, good; one of 60 to 79 points, fair; and one of less than 60 points, poor. In addition to the Harris hip score, the guidelines of the Hip Society²⁷ were used to evaluated the level of activity, working capacity, ability to stand from a sitting position, and satisfaction of the patient. Pain in the thigh was graded as mild when it was occasional, did not interfere with daily activities, and did not necessitate the use of pain medication; as moderate when it led to a modification of daily activities and the occasional use of nonsteroidal anti-inflammatory medication; and as severe when it was constant, necessitated the use of narcotics, and interfered with daily activities.

Radiographic Evaluation

Standard anteroposterior and lateral radiographs of the involved hip with magnification markers and an anteroposterior radiograph of the pelvis were made preoperatively and at each follow-up examination. Radiographic evaluation was performed with use of the guidelines of the Hip Society²⁷. This assessment included evaluation of calcar remodeling and pedestal formation. The quality of the femoral bone was evaluated preoperatively by rating the cancellous trabeculae in the proximal part of the femur with use of the index of Singh et al.⁴². The method of Engh et al.^13,15,16 was used to classify the fixation of the implant as bone ingrowth, stable fibrous, or unstable fibrous.

Radiodense and radiolucent lines around the femoral component were evaluated, and their location was identified according to the zones described by Gruen et al.²¹. Osteolysis of the pelvis and femur was evaluated according to a modification of the system developed by the American Academy of Orthopaedic Surgeons, as described by Weber et al.⁴⁵. Defects were considered important if they measured two millimeters in diameter or more.

The press-fit of the implant, as assessed on the first standardized postoperative radiograph (made six weeks after the operation), was recorded as excellent, good, or poor on the basis of the amount of contact between the stem and the endosteum, as described by Callaghan et al.^7,25. Vertical migration (subsidence) of the femoral component was evaluated by measuring the change in the distance between the most proximal point of the lesser trochanter and the most superomedial point of the femoral component on sequential radiographs. As described by Callaghan et al.^7,25, five millimeters or more was considered to indicate subsidence. The classification system of Brooker et al.^5,27 was used to grade heterotopic ossification when it was present.

Radiolucent lines around the acetabular component were evaluated, and their location was identified according to the zones described by DeLee and Charnley¹⁰. Osteolysis of the pelvis was assessed as previously described for osteolysis of the femur. Migration of the acetabular component was evaluated by measuring the vertical distance between the center of the cup and a line joining the teardrops as well as by measuring the horizontal distance between the center of the cup and a vertical line through the teardrop. Migration of five millimeters or more was considered to be notable¹. The inclination of the acetabular cup from the horizontal (the cup angle) was measured by drawing a horizontal line through both teardrops and another line through the plane of the opening of the cup^7,25. Any change of more than 5 degrees in this angle on sequential radiographs was considered important³². Polyethylene wear was measured by comparing the first standardized postoperative anteroposterior radiograph with the most recent follow-up anteroposterior radiograph of the hip with use of the method of Livermore et al.³³. One of us (V. M. G.) performed all of the measurements. The relationships between polyethylene wear and the size and position of the cup, the duration of implantation, and the body weight and the age of the patient were determined statistically with analysis of variance.

Results

Introduction | Materials and Methods | Results | Discussion | References

Clinical Findings

The average preoperative Harris hip score was 48 points (range, 24 to 67 points), with an average pain score of 15 points (range, 0 to 20 points) and an average function score of 26 points (range, 9 to 40 points). At the time of the most recent follow-up visit, the average Harris hip score was 96 points (range, 69 to 100 points), with an average pain score of 42 points (range, 30 to 44 points) and an average function score of 45 points (range, 28 to 47 points).

The result was excellent for eighty-two hips, good for thirteen, and poor or a failure for two. After all of the ninety-five arthroplasties that yielded a good or excellent result, the patients resumed daily activities, obtained their desired goals from the operation, and were capable of standing from a sitting position. None of these patients needed walking aids, walked with a limp, or were unable to put on their socks and shoes. The prevalence of pain in the anterior part of the thigh or the groin, or both, was 5 percent (five hips). Four patients had pain in the thigh only, and one had pain in both the thigh and the groin. The pain was mild in four patients, but it was severe in one, who had aseptic loosening. We detected no association between pain in the thigh and the size of the stem that had been implanted. The patient who died during the follow-up period had, at his last visit nine months after the operation, a Harris hip score of 81 points and no pain in the thigh or the groin.

Radiographic Findings

Femoral Component

Preoperatively, the quality of the femoral bone, as assessed radiographically with use of the index of Singh et al.⁴², was grade 6 in forty hips (41 percent), grade 5 in thirty (31 percent), grade 4 in sixteen (16 percent), and grade 3, 2, or 1 in eleven (11 percent). At the time of follow-up, ninety-four (97 percent) of the ninety-seven stems were fixed by bone, two (2 percent) had stable fibrous fixation, and one (1 percent) had had unstable fibrous fixation and had been revised. The unstable stem had subsided five millimeters during the first eighteen months after the operation. Twenty-seven (28 percent) of the femoral components were associated with slight pedestal formation, as seen on both the anteroposterior and the lateral radiograph. However, all twenty-seven stems were stable so the slight pedestal formation was not considered an important finding. Only the stem that had subsided was associated with extensive pedestal formation, as seen on both the anteroposterior and the lateral radiograph.

Twenty-seven stems had been implanted in neutral, and seven components had been placed in varus angulation. The remaining sixty-three stems were in the correct (valgus) position. Except for the subsided stem, which was associated with a radiolucent line that was three millimeters in thickness, no femoral component was associated with a complete radiolucent line of more than two millimeters in thickness. However, nonprogressive radiolucent lines of less than two millimeters in thickness were seen adjacent to eight stems, in zones 1 and 2²¹. There was no osteolysis around any of the femoral components. Resorption of the calcar, which averaged 1.3 millimeters, was observed in association with sixty-three stems. The press-fit of the component^7,25, as assessed on the first postoperative anteroposterior radiograph, was excellent in fifty-eight hips, good in thirty-eight hips, and poor in one hip. As assessed on the lateral radiograph, the press-fit was excellent in ninety-six hips and poor in the one hip in which the femoral component had subsided. Calcar-rounding was identified in association with thirty-four stems (Fig. 2). Heterotopic ossification was identified in nineteen hips. It was class III in six hips⁵, but no hip had class-IV ossification.

Acetabular Component

Four hips had nonprogressive osteolytic lesions that were less than two millimeters in diameter, in zones 1 and 2¹⁰. No radiolucent line of more than two millimeters in thickness was seen. Twelve acetabular components were associated with a radiolucent line of less than two millimeters in zones 1 and 2, and ten components were associated with a radiolucent line of less than two millimeters in zone 3. There was no notable horizontal or vertical migration of the cup. The average angle of inclination was 40.5 degrees (range, 35 to 60 degrees), and the average change in inclination was 2.2 degrees (range, 0 to 5 degrees). There were no broken screws.

Thirty acetabular components demonstrated polyethylene wear of 0.5 to 1.0 millimeter (average [and standard deviation], 0.85 ± 0.5 millimeter), as assessed on the most recent follow-up radiograph, and twelve acetabular components demonstrated polyethylene wear of 1.1 to 2.0 millimeters (average, 1.2 ± 0.8 millimeters). All cups that had more than 1.0 millimeter of wear had a fifty-four-millimeter-diameter shell and a polyethylene thickness of 7.3 millimeters. With the numbers available, we were unable to detect a relationship between polyethylene wear and the size or position of the cup, the duration of implantation, or the body weight or the age of the patient (p > 0.05).

Complications

Dislocation occurred in two hips, which were treated successfully with closed reduction and a brace. Deep-vein thrombosis developed after two arthroplasties. Class-III heterotopic ossification⁵ developed in six hips, without sequelae. Complications that led to a revision operation included a hematogenous infection that developed in one hip three years after the index procedure and a fracture adjacent to one femoral component that occurred three years after the index procedure. The latter component was replaced with a larger and longer prosthesis. One patient had a revision operation because of a 0.5-inch (1.27-centimeter) limb-length discrepancy one year after the operation. At the time of the revision, the implants were stable and only the head and neck of the femoral component were exchanged. Only two revisions were performed because of mechanical failure; therefore, the total rate of mechanical failure was 2 percent. In one of these revisions, the acetabular component was replaced because of recurrent dislocations. The stem was stable at the time of the operation and was not replaced. The other revision that was due to mechanical failure was done, eighteen months after the index procedure, because of aseptic loosening manifested by severe pain in the thigh and subsidence of the femoral component (Fig. 3).

Discussion

Introduction | Materials and Methods | Results | Discussion | References

Our study of 100 consecutive primary total hip arthroplasties with insertion of an anatomically designed femoral component without cement in patients who had osteoarthritis demonstrated improved clinical and radiographic outcomes compared with those associated with early designs of prostheses inserted without cement^{4,6-8,29,34,35}. Excellent or good pain relief and function were obtained after 95 percent of the 100 procedures, which were performed in a population of active patients. The average Harris hip score was 96 points. Bourne et al.⁴, in a study of 101 total hip replacements with the PCA (porous-coated anatomic) prosthesis (Howmedica, Rutherford, New Jersey), reported an average Harris hip score of 96 points, but only patients who were free of pain were evaluated; when patients who had pain were included, the overall average score was 90 points. Heekin et al.²⁵ reported an average score of 93 points after a minimum of five years of follow-up of ninety-one hips that had been treated with the PCA prosthesis. In a study by Katz et al.²⁹ of the results of fourteen arthroplasties in which the stem had been fixed without cement, the hip score averaged 84 points at forty-six months. Barrack and Lebar² reported an average Harris hip score of 93 points after forty-nine arthroplasties in which the LSF (long-term stable fixation) prosthesis (OTI [Osteoimplant Technology International], Hunt Valley, Maryland) had been used.

Pain in the thigh occurred after only 5 percent (five) of the total hip arthroplasties in the present study, and we detected no association between pain in the thigh and the size of the stem. In other studies^4,8 in which a PCA prosthesis had been used, pain in the thigh occurred after 13 percent (fourteen) of 111 arthroplasties, 22 percent (twenty-four) of 110 arthroplasties, and 27 percent (twenty-seven) of 101 arthroplasties at one, two, and five years, respectively. Callaghan et al.⁷ reported that eight of forty-six patients (forty-nine hips) had pain in the thigh at two years after an arthroplasty with use of the PCA stem. Heekin et al.²⁵ reported pain in the thigh in association with 15 percent of ninety-one hips at five years in a study of a similar population.

The influence of the design of the implant on the clinical results of total hip arthroplasty without cement was emphasized by Haddad et al.²³. In their comparison of three different types of porous-coated hip replacements without cement, the highest average Harris hip score and the lowest prevalence of pain in the thigh (8 percent; four stems) were observed in association with the fifty hips in which an anatomically shaped femoral component had been implanted. Recently, Tankersley et al.⁴³ compared the clinical and radiographic outcomes of procedures with so-called first-generation PCA prostheses with those of procedures with so-called second-generation PCA E-series prostheses inserted without cement. The second-generation stems were modified to improve their stability and distal curve. These differences in design led to an improvement in the average Harris hip score to 94 points in forty-two hips compared with 81 points in forty-two hips that had been treated with the first-generation implant. The similar design features of the stem used in our study may have contributed to our favorable clinical results.

Other reports have suggested that the difference in design also leads to variations in radiographic outcome. Haddad et al.²³ reported that curved stems resulted in a lower prevalence of calcar-rounding and subsidence. Tankersley et al.⁴³ also indicated that prosthetic designs that improved fixation resulted in a lower prevalence of femoral radiolucent lines. Only 1 percent (one) of the femoral implants in our study subsided; however, the prevalence of medial calcar-remodeling was 34 percent (thirty-four stems). The high prevalence of medial calcar-remodeling may have been due to the lower modulus of titanium alloy compared with that of cobalt-chromium alloy or to the position and extent of the proximal porous coating. However, calcar-remodeling had no adverse effect on the clinical or functional outcome.

Another factor that may be of importance in determining the outcome of arthroplasties without cement is the selection of the patients. Rheumatoid arthritis, avascular necrosis, or congenital hip dysplasia may influence the biological integration of the implant and bone-remodeling⁸, thereby affecting the overall outcome. Mont et al.³⁸ reported favorable results of total hip replacements without cement in patients with non-inflammatory osteoarthritis who were less than forty-five years old. In contrast, Bourne et al.⁴, who studied the outcomes of total hip replacement with insertion of a PCA prosthesis without cement in patients who had advanced osteoarthritis, reported pain in the thigh five years after 27 percent (twenty-seven) of 101 arthroplasties and more than two millimeters of subsidence of the femoral component in twenty-five hips. We studied a similar group of patients, but the stem that we used was associated with an improved Harris hip score and a reduction in the prevalence of both pain in the thigh and subsidence of the femoral implant.

The success of biological fixation depends on the initial stability as well as the design of the femoral component³⁹. In a study with a minimum duration of follow-up of five years, Heekin et al.²⁵ reported bone ingrowth after 94 percent of 100 primary arthroplasties performed with use of a curved stem with a circumferential coating, stable fibrous fixation after 1 percent, and unstable fibrous fixation after 5 percent. In a study of the results of total hip arthroplasty with use of an extensively coated straight-stem femoral component, Engh et al.¹⁷ reported bone-growth fixation of 90 percent (105) of 117 components, stable fibrous fixation of 9 percent (ten), and unstable fibrous fixation of 2 percent (two) after an average of eleven years of follow-up. These data, when compared with those reported in the present study, suggest improved osseous integration of stems with an extensive circumferential porous surface.

Extensive pedestal formation is considered another potential radiographic sign of instability of the implant. In the present study, a slight pedestal was seen on the anteroposterior and lateral radiographs of 28 percent (twenty-seven) of the stems. All of these stems were fixed by bone ingrowth. Only the one loose stem in our study had subsided notably. In contrast, Campbell et al.⁸ reported that 25 percent (twenty-eight) of 110 stems had notable subsidence at two years, and Barrack and Lebar² found that 6 percent (three) of forty-nine stems had subsided at least three to four millimeters. Femoral osteolysis was not seen in our study; however, our follow-up may have been too short. Studies^19,46 with longer follow-up have demonstrated a notably higher prevalence of femoral osteolysis.

Although the present study emphasized the femoral component, we also evaluated the acetabular component. We encountered no notable horizontal or vertical migration and no areas of osteolysis of more than two millimeters in diameter. These results are comparable with those of other studies of different types of acetabular components that were followed for a similar interval^30,44.

Our study had a number of limitations. The hips, although consecutive, were nonrandomized and selected, which could have biased the results. Furthermore, although the radiographs were standardized, differences in the technique could have resulted in an underestimation of the presence of osteolytic lesions or radiolucent lines. In addition, all operations were performed by one surgeon and these results may not necessarily be reproducible by other surgeons. We considered performing a Kaplan-Meier survivorship analysis²⁸ with revision because of a mechanical complication or radiographic evidence of loosening of either the femoral or the acetabular component as the end points. However, as only two hips met these criteria, early in the study, the Kaplan-Meier method may not reflect survival in this study.

In conclusion, the outcome of total hip arthroplasty without cement is determined by multiple factors, including the design of the component, the selection of the patients, and the operative technique. The results of the procedure must be evaluated in long-term studies because many reconstructions without cement are performed in younger, healthy patients. Our study suggests that so-called second-generation femoral implants without cement can provide satisfactory clinical and radiographic outcomes after an intermediate duration of follow-up. These results appear to be better than those obtained with early designs of total hip components without cement. The circumferential proximal porous surface and the anatomical design provide reliable initial biological fixation, osseointegration, and few femoral or acetabular osseous changes. However, longer clinical observation is mandatory to determine the long-term results of total hip arthroplasty with this implant and to understand the role and the applicability of this technology to hip replacement.

References

Introduction | Materials and Methods | Results | Discussion | References

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