| | Tight Fit Technique in Primary Hybrid Total Hip Arthroplasty for Patients with Hip DysplasiaReceived 13 July 2005; accepted 14 January 2006. published online 14 April 2006. Abstract This article presents the midterm results of hybrid total hip arthroplasty for patients with hip dysplasia by use of a tight fit technique for the femoral component. We followed up 113 hips in 99 patients for a mean of 11 years. All final femoral rasps used in this study overrasped by 0.5 to 1.0 mm for stem insertion, resulting in relatively thin cement mantles. Both components of one hip were removed because of infection. The other 5 acetabular components were revised for osteolysis, recurrent dislocation, or dislodgement of the polyethylene liner. No femoral component was revised for aseptic loosening. We conclude that the tight fit technique using a canal-filling stem may produce good long-term results for patients with hip dysplasia. Many laboratory, clinical, and retrieval studies have reported that cement mantles of femoral components should have a minimal thickness of 2 to 4 mm and should be complete 1, 2, 3, 4, 5, 6, 7, 8. These studies suggested that femoral osteolysis with or without loosening of the implant would likely occur when the cement mantles are thin, are partially deficient, or include voids. On the other hand, Langlais et al [9] showed good clinical results with a thin cement mantle technique that used 2 French-designed, cemented femoral components, the Charnley-Kerboull 10, 11, 12 and the Ceraver Osteal 13, 14, which are both intended to fully occupy the medullary canal of the femur. Skinner et al [15], using the Freeman cobalt-chrome femoral component with this technique, also reported good clinical results. The final diameter of the reamer they used was the same or 2 mm greater than that of the final prosthesis. Currently, the ideal thickness of the cement mantle for the femoral component is controversial. Total hip arthroplasty for patients with osteoarthrosis secondary to developmental dysplasia of the hip presents specific problems including a narrow femoral canal [16]. A tighter fit achieved by use of a femoral component as large as possible may be important for these patients. We have used consecutively smaller final femoral rasps than those recommended by the manufacturer in hybrid total hip arthroplasty since 1987. This technique might result in thinner cement mantles. The purpose of this study was to evaluate the intermediate-term follow-up results of the tight fit technique for patients with hip dysplasia and to investigate whether this technique resulted in a high failure rate. Materials and Methods  Between March 1987 and December 1997, 140 consecutive primary hybrid total hip arthroplasties were performed on 125 patients to treat advanced osteoarthritis secondary to developmental dysplasia of the hip. Sixteen patients (17 hips) died before the 7-year follow-up. Five patients (5 hips) became bedridden and were too ill to return for follow-up evaluation. Five patients (5 hips) were lost to follow-up. These 27 total hip arthroplasties were well fixed at the previous follow-up, and these patients were excluded from the study. The remaining 113 hips in 99 patients were available for clinical and radiographic review. The average duration of follow-up was 11.0 years (range, 7.0-17 years). The average age at the time of the index operation was 62 years (range, 26-88 years). The average weight was 56 kg (range, 41-95 kg). Twelve patients were men and 77 were women. There were 55 right hips and 58 left hips. During the same period, cementless total hip arthroplasties were performed on patients younger than 55 years who had good femoral cortical bone quality. All of the procedures were performed through the posterolateral approach without trochanteric osteotomy. A Harris Precoat, Precoat Plus, or CDH Precoat stem (Zimmer, Warsaw, Ind) was used in 91 hips (Fig. 1A-C). A CDH stem was used in 8 hips, a small stem in 11 hips, a small plus stem in 33 hips, a medium stem in 30 hips, a large stem in 8 hips, and a large plus stem in one hip. Elite Plus stem (DePuy, Warsaw, Ind) was used in 22 hips (Fig. 1D). A size 1 stem was used in 3 hips, a size 2 stem in 9 hips, a size 3 stem in 6 hips, a size 4 stem in 3 hips, and a size 5 stem in 1 hip. The dimensions of the Precoat or Precoat Plus small stem were almost equivalent to that of the Elite Plus size 1 stem, the small plus stem to the size 2 stem, the medium stem to the size 3 stem, the large stem to the size 4 stem, and the large plus stem to the size 5 stem. The average surface roughness was 2.0 μm in the Harris Precoat stem, 2.2 μm in the Harris Precoat Plus or CDH Precoat stem, and 0.5 to 0.6 μm in the Elite Plus stem. We asked the manufacturers to provide femoral rasps for each final component, which overrasped by 0.5 mm for the Harris Precoat, Precoat Plus, and CDH Precoat stem, and 1.0 mm or less for the Elite Plus stem. All final femoral rasps used for canal preparation in this study overrasped by 0.5 mm for the Harris Precoat, Precoat Plus, and CDH Precoat stems, and by 1.0 mm or less for the Elite Plus stems. A so-called second-generation cementing technique was used with Simplex cement (Stryker-Howmedica-Osteonics, Mahwah, NJ) and a cement gun for the retrograde introduction of cement (Fig. 2). A methylmethacrylate plug was used in all but 12 hips. No plug was used in the first 4 hips. In 8 subsequent hips, which had the CDH Precoat stem inserted, the canal was too narrow to accept a plug. We did not use vacuum mixing, centrifugation, proximal cement pressurizers, or stem centralizers. A titanium hemispherical Harris-Galante porous-coated 1 or 2 acetabular component (Zimmer) was used in 91 hips, and Duraloc 1200 acetabular component (DePuy) was used in 22 hips. An average of 3.5 screws (range, 2-6 screws) was used for fixation. The average outer diameter of the acetabular component was 51 mm (range, 40-64 mm). The diameter of the prosthetic femoral head was 22 mm in all hips. Clinical evaluations were made according to the Harris hip scoring system [17]. An anteroposterior radiograph and a true lateral radiograph were made preoperatively and at each follow-up examination. Preoperative, immediate postoperative, and all intermediate radiographs as well as those obtained at the latest follow-up visit were analyzed by orthopedic surgeons other than the operating surgeon. Cementing of the femoral stem was classified as grade A, B, C-1, C-2, and D according to the method described by Mulroy et al [18]. The alignment of the femoral component was classified as valgus, neutral, or varus, as seen on anteroposterior radiographs. Femoral osteolysis was defined as areas of endosteal, intracortical, or cancellous loss of bone that were scalloped or had the appearance of bone destruction rather than disuse osteopenia. A linear radiolucent zone more than 2 mm wide was deemed as osteolysis. The dimensions and location of radiolucent lines at the bone-cement interface of the femoral component and osteolytic lesions were recorded according to the zones of Gruen et al [19]. The thickness of the femoral cement mantle was measured in 12 zones of the femur. If the outer border of the mantle was difficult to identify against cortical bone with no intervening cancellous bone, the thickness of the cortical bone seen on preoperative radiographs was used. The magnification ratio for each radiograph was determined by measuring the diameter of the prosthetic femoral head and dividing it by the known diameter of the femoral head. The canal-filling ratio of the femoral component was defined as the percentage of component width to intramedullary width at the midpoint of the component on an anteroposterior radiograph taken within 1 month after surgery [20]. Loosening of the femoral component was defined by using the criteria described by Harris et al [21]. Definite loosening was defined as migration of the component or cement mantle, bending or breakage of the stem, or cement fracture. Debonding of the cement-metal interface, as seen by a radiolucent line of any width at this interface, was considered to indicate subsidence of the stem and was classified as loose. The acetabular interface on the anteroposterior radiograph was divided into 3 zones as described by DeLee and Charnley [22]. The acetabular component was classified as migrated if there was a change of at least 4 mm in the horizontal or vertical position of the center of the component compared with that seen on the immediate postoperative anteroposterior radiograph [23]. Linear head penetration into the polyethylene liner was measured by using the techniques described by Livermore et al [24]. Statistical analyses were performed by using χ2 tests and Kruskal-Wallis test. Probability values less than .05 were considered significant. Kaplan-Meier survivorship analysis was used to calculate the probability of retention of the original prosthesis with 95% confidence intervals (CIs; StatView; SAS Institute Inc, Cary, NC). Results At the time of the most recent follow-up, revisions had been performed in 6 hips in 6 patients. Both acetabular and femoral components of one hip with postoperative infection were simultaneously removed 10 months after index surgery. None of the femoral components were revised for aseptic loosening. Another 5 acetabular components were revised; 1 for osteolysis around the acetabular component, 3 for recurrent dislocation, and 1 for dislodgement of the polyethylene liner from the metal shell. The Kaplan-Meier survivorship analysis, with failure defined as revision surgery, demonstrated that the probability of retention of the femoral component 15 years after surgery was 99% (95% CI, 0.98-1.0) and that of the acetabular component 15 years after surgery was 94% (95% CI, 0.91-0.97). The Harris hip score increased from a preoperative average of 45 points (range, 24-78 points) to 86 points (range, 42-100 points) at the most recent follow-up. One femoral component was revised because of infection, as described above. None of the other 112 femoral components showed possible, probable, or definite loosening at the most recent follow-up. The position of the femoral component was neutral in 68 hips, valgus in 40 hips, and varus in 5 hips. The cementing of the femoral component was grade A in 6 hips, grade B in 26, grade C-1 in 38, grade C-2 in 41, and grade D in 2. Grade C-1 was mainly due to the presence of small voids, grade C-2 to the presence of a thin mantle of cement, and grade D to insufficient cement mantle distal to the tip of the stem. The cement thickness for 4 types of the femoral component (Table 1) and the cement thickness for 6 sizes of the femoral component (Table 2) indicated that cement mantles of the CDH Precoat stem were a little thinner than those of other stems; however, no significant difference was found in each zone. Relationship among 4 types of the femoral component and various factors is shown in Table 3. Although the mean canal-filling ratio of the CDH Precoat stem was a little lower, no significant difference was found among 4 types of the femoral component. All femoral radiolucent lines were located in the most proximal zones (zones 1 and 7) and none of the femurs showed any radiolucent lines other than in the most proximal zones. Femoral osteolysis was also localized in zone 1 or 7. Ten hips had dislocated posteriorly. Of the 10 hips, 3 had undergone revision of the acetabular component for recurrent dislocation. | | |  | Femoral zone | Cement thickness (mm)⁎ | P | |
|---|
| CDH Precoat (n = 8) | Precoat (n = 15) | Precoat Plus (n = 68) | Elite Plus (n = 22) | Total (n = 113) | |
|---|
| 1 | 1.3 ± 0.8 | 2.0 ± 0.6 | 2.1 ± 0.7 | 2.2 ± 0.7 | 2.1 ± 0.8 | .065 | | | 2 | 1.4 ± 0.9 | 1.7 ± 1.3 | 1.9 ± 1.2 | 1.4 ± 1.2 | 1.7 ± 1.2 | .161 | | | 3 | 2.3 ± 1.0 | 3.0 ± 0.5 | 2.8 ± 0.8 | 2.6 ± 0.8 | 2.8 ± 0.8 | .162 | | | 5 | 1.2 ± 1.1 | 1.2 ± 1.1 | 1.1 ± 0.9 | 1.8 ± 1.2 | 1.2 ± 1.0 | .087 | | | 6 | 2.2 ± 0.5 | 2.7 ± 1.0 | 2.6 ± 0.9 | 2.4 ± 0.9 | 2.5 ± 0.9 | .457 | | | 7 | 2.0 ± 1.5 | 1.9 ± 0.8 | 2.3 ± 0.9 | 1.9 ± 1.0 | 2.1 ± 1.0 | .227 | | | 8 | 2.1 ± 0.8 | 2.1 ± 0.6 | 2.0 ± 0.7 | 1.8 ± 0.7 | 2.0 ± 0.7 | .377 | | | 9 | 2.1 ± 1.2 | 2.2 ± 0.9 | 2.1 ± 0.8 | 2.2 ± 0.7 | 2.1 ± 0.8 | .813 | | | 10 | 2.6 ± 1.4 | 3.6 ± 1.6 | 3.7 ± 2.0 | 4.2 ± 1.7 | 3.7 ± 1.9 | .084 | | | 12 | 2.6 ± 2.3 | 3.2 ± 1.6 | 2.8 ± 1.1 | 2.9 ± 1.0 | 2.8 ± 1.2 | .129 | | | 13 | 2.1 ± 1.2 | 2.6 ± 1.0 | 2.6 ± 0.9 | 2.8 ± 1.0 | 2.6 ± 0.9 | .427 | | | 14 | 2.1 ± 1.2 | 3.0 ± 1.0 | 2.7 ± 0.7 | 2.7 ± 0.7 | 2.7 ± 0.8 | .227 | | | | |
Six acetabular components were revised as described above. The average postoperative angle of abduction of 107 acetabular components at the most recent follow-up was 46° (range, 25°-63°). Radiolucent lines were observed around 19 (18%) acetabular components. These lines were all 1 mm wide or less, occurred in zone 1 in 10 hips, in zone 2 in 12 hips, and in zone 3 in 7 hips. There were no sockets showing a continuous radiolucent line. Pelvic osteolytic lesions were observed adjacent to the acetabular component in 4 (4%) hips. Of the 4 hips with pelvic osteolysis, 2 showed radiolucent lines around the corresponding femoral component. One involved an osteolytic area (12 by 15 mm) in zones 1 and 2, in which morseled fresh-frozen bone allograft was performed 10.4 years after the index procedure. The average rate of head penetration into the polyethylene liner was 0.09 mm (range, 0-0.29 mm) per year. One patient had mild sciatic nerve palsy, which resolved nearly completely within 18 months. There were no clinically evident pulmonary embolisms. Discussion Thin or incomplete cement mantles have been reported to be responsible for irregular stress distribution, mantle fracture, stem debonding, osteolysis, and loosening 1, 2, 3, 4, 5, 6, 7, 8. Ebramzadeh et al [1] reported the results of 836 cemented femoral components at an average follow-up of 9 years, in which stems with a 2- to 5-mm-thick cement mantle in the proximal medial region had a better outcome than those with a thicker or thinner cement mantle. Joshi et al [3] reported the results of 249 Charnley primary arthroplasties at a minimum follow-up of 10 years, in which significant factors that reduced osteolysis were femoral cement mantles of 3 mm in all zones and a canal-filling ratio of 60% to 70%. Valdivia et al [25] evaluated the cement mantle thickness of the femoral component by using different designs by computer-assisted analysis and reported that the mean mantle thickness was 3 to 4 mm, with significantly different variability between the stems. They also reported that the mean mantle thickness by region and segment was greater than 2 mm in most femoral components and recommended at least 2-mm cement mantle thickness, which requires sufficient intraoperative overrasping or overreaming of the femur. On the other hand, good clinical results have been reported with a thin cement mantle technique. Nizard et al [13] reported that the survival rate of 187 Ceraver Osteal stems at 10 years was 99.2%. Kerboull [11] reported that 1% to 2% aseptic loosening of the CK mark I Charnley-Kerboull stem was observed at an average follow-up of 20 years. Skinner et al [15] reported that the survival rate of the cemented Freeman cobalt-chrome stem at 10 years was 97.2% in 92 hips in which the canal was overreamed by 2 mm and 98.8% in 97 hips in which the canal was reamed to the same size as the prosthesis. The thin cement mantle technique was introduced by Postel et al [26] and is widely used in France [9]. Langlais et al [9] introduced the design philosophy of the Charnley-Kerboull and the Ceraver Osteal stems, which includes very thin and sometimes incomplete cement mantles. They commented that the vigorous insertion of a canal-filling stem into doughy cement would produce a marked pressure increase at the cement-bone interface during stem insertion, and stronger initial mechanical interlocking at the cement-bone interface could be obtained. Kerboull [10] recommended complete removal of the cancellous bone in the medullary canal before filling with cement and forcing in a well-fitting prosthetic stem that would almost fill the medullary cavity. Similarly, Witvoet [14] described the operative technique used with the Ceraver Osteal stem, in which surgeons tried to fill the medullary femoral canal as much as possible with the largest possible stem, which requires boring the medullary cavity in a number of cases. They did not recommend trying to achieve a continuous cement mantle. These canal-filling stems require hammer blows to complete their insertion [26]. Skinner et al [15] reported two advantages of the thin cement mantle technique: first, if a prosthesis is used to pressurize the cement, a higher pressure is produced by the tighter fit; second, the tight fit immobilizes all the cement interfaces while the cement sets. Song et al [27] showed that if intrafemoral pressure was measured continuously throughout cementation, stem insertion generated the highest pressure, suggesting that prior pressurization may be unnecessary. Skinner et al [15] commented that eliminating micromovement during this vital period has profound and long-lasting effects for 20 years. They concluded that it was incorrect to insert a femoral prosthesis with a thick and complete cement mantle. We think that the tighter fit of the femoral component is technically important for patients with a narrow femoral canal and our results support these previous studies. We agree that the ideal thickness of the cement mantle for the femoral component is controversial. Many studies have reported that a thin or incomplete cement mantle should be avoided 1, 2, 3, 4, 5, 6, 7, 8, 25. However, Brown and Bargar [28] showed that 1.6-mm thin specimens demonstrated an increase in stress failure of 14% and an increase in strain failure of 30% compared with 3.2-mm thicker specimens. Hertzler et al [29] reported that the fatigue crack growth rate did not depend on cement mantle thickness in an experimental study that used a cyclic torsional loading system, in which constructs with 1-mm (thin), 3-mm (medium), or 7-mm (thick) cement mantles were used. The previous good results 11, 12, 13, 14, 15 and our results obtained by using the tight fit technique with relatively thin cement mantle coincide with the results of these laboratory studies. We also agree that the ideal canal-filling ratio is controversial. The thin cement mantle technique tends to require a high canal-filling ratio. Joshi et al [3] reported that cement mantles of 3 mm in all zones of the femur and a canal-filling ratio of 60% to 70% were favorable factors to reduce osteolysis. Kobayashi and Terayama [20] reported that a canal-filling ratio of 75% or higher correlated positively with survival of the femoral component. The average canal-filling ratio of 75.3% in this study was comparable to these previous studies. Although there have been no published reports describing the histology at the long-term bone-cement interface in relation to these canal-filling stems, it is supposed that the mechanical load may be directly transmitted from the stem to bone favorably without compromising the cement. Although each final femoral rasp we used was 0.5 to 1.0 mm larger than the inserted femoral component, the measured cement mantles were thicker than we expected. An average cement thickness in some zones was less than 2 mm; however, traditionally recommended cement thickness of greater than 2 mm was more frequently observed. Skinner et al [15] also reported that the mean cement thickness measured in various section levels of the stem was all 2 mm or greater in the experimental cadaver study using the thin cement mantle technique. These results suggest that the thin cement mantle technique does not necessarily produce really “thin cement mantle.” Either the rasping technique, leading to larger canal preparation, or the pressure of the stem in a tight canal, resulting in more cement penetration into the bone, might likely be responsible. Using the thin cement mantle technique, Langlais et al [9] described that French stems, provided that their surfaces are polished, function well in the medium and long term, although the cement mantles are extremely thin and may be incomplete. The average surface roughness of the stem used in this study was 0.5 to 2.2 μm, suggesting that good results can be expected even if rougher surface stems are used. Various factors can influence the early and long-term survival of the femoral component. In addition to the variables of cement mantle thickness and surface finish, additional variables such as stem geometry, offset, operative techniques, and patient population may all play important roles in the durability of a femoral component. Valdivia et al [25] reported that standard anteroposterior radiographs overestimated cement mantle thickness and underestimated deficiencies when compared with computed tomographic scan measurements by Gruen zones. We measured the thickness of the cement mantles only on plain radiographs; thus, it is possible that we overestimated the thickness of the cement mantles, which was one weakness of this study. However, even if the cement mantles were thinner, our good results indicated the usefulness of this tight fit technique with relatively thin cement mantles. We agree with Skinner et al [15] that a press-fit stem supplemented with cement is as good as, if not better than, other techniques. We believe that the intraoperative higher pressure on the cement by the tighter fit during stem insertion and the use of a canal-filling stem in which the stem to bone load may be directly transmitted are the two most important advantages of this tight fit technique. References 1. 1Ebramzadeh E, Sarmiento A, McKellop HA, et al. The cement mantle in total hip arthroplasty: analysis of long-term radiographic results. J Bone Joint Surg Am. 1994;76:77. MEDLINE 2. 2Fisher DA, Tsang AC, Paydar N, et al. Cement mantle thickness affects cement strains in total hip replacement. J Biomech. 1997;30:1173. Abstract |
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3. 3Joshi RP, Eftekhar NS, McMahon DJ, et al. Osteolysis after Charnley primary low-friction arthroplasty: a comparison of two matched paired groups. J Bone Joint Surg Br. 1998;80:585.
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4. 4Kawate K, Maloney W, Bragdon CR, et al. Importance of a thin cement mantle: autopsy studies of eight hips. Clin Orthop. 1998;355:70.
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5. 5Kawate K, Ohmura T, Hiyoshi N, et al. Thin cement mantle and osteolysis with a pre-coated stem. Clin Orthop. 1999;365:124.
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7. 7Ritter MA, Zhou H, Keating CM, et al. Radiological factors influencing femoral and acetabular failure in cemented Charnley total hip arthroplasties. J Bone Joint Surg Br. 1999;81:249. 8. 8Star MJ, Colwell CW, Kelman GJ, et al. Sub-optimal distal cement mantle thickness as a contributory factor in total hip arthroplasty femoral component failure: a retrospective analysis favouring distal cement centralisation. J Arthroplasty. 1994;9:143. Abstract |
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9. 9Langlais F, Kerboull M, Sedel L, et al. Annotation: the ‘French paradox’. J Bone Joint Surg Br. 2003;85:17.
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10. 10Kerboull M. The Charnley-Kerboull prosthesis. In: Postel M, Kerboull M, Evrard J editor. Total hip replacement. Berlin: Springer Verlag; 1987;p. 13. 11. 11Kerboull M. L'arthroplastie totale de hanche. Maîtrise Orthopédique. 1999;83:6. 12. 12Kerboull L, Hamadouche M, Kerboull M. Long term results of Charnley-Kerboull total hip replacement in patients younger than 50. In: Caton J, Ferreira A, Picault C editor. Arthroplastie totale de hanche. Lyon: Transit Communications; 2000;p. 37. 13. 13Nizard RS, Sedel L, Christel R. Ten year survivorship of cemented ceramic-ceramic total hip prostheses. Clin Orthop. 1992;282:53. 14. 14Witvoet J. Long-term results of titanium alloy smooth cemented femoral stem. In: Caton J, Ferreira A, Picault C editor. Arthroplastie totale de hanche. Lyon: Transit Communications; 2000;p. 237. 15. 15Skinner JA, Todo S, Taylor M, et al. Should the cement mantle around the femoral component be thick or thin?. J Bone Joint Surg Br. 2003;85:45.
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16. 16Jaroszynski G, Woodgate I, Saleh K, et al. Total hip replacement for the dislocated hips. J Bone Joint Surg Am. 2001;83:272. 17. 17Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fracture: treatment by mold arthroplasty. J Bone Joint Surg Am. 1969;51:737. MEDLINE 18. 18Mulroy WF, Estok DM, Harris WH. Total hip arthroplasty with use of so-called second-generation cementing techniques: a fifteen-year-average follow-up study. J Bone Joint Surg Am. 1995;77:1845. MEDLINE 19. 19Gruen TA, McNeice GM, Amstutz HC. “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop. 1979;141:17. 20. 20Kobayashi S, Terayama K. Factors influencing survivorship of the femoral component after primary low-friction hip arthroplasty. J Arthroplasty. 1992;7(Suppl):327. Abstract |
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21. 21Harris WH, McCarthy JC, O'Neill DA. Femoral component loosening using contemporary techniques of femoral cement fixation. J Bone Joint Surg Am. 1982;64:1063. MEDLINE 22. 22DeLee JG, Charnley J. Radiographical demarcation of cemented sockets in total hip replacement. Clin Orthop. 1976;121:20. 23. 23Russotti GM, Harris WH. Proximal placement of the acetabular component in total hip arthroplasty: a long-term follow-up study. J Bone Joint Surg Am. 1991;73:587. MEDLINE 24. 24Livermore J, Ilstrup D, Morrey B. Effect of femoral head size on wear of the polyethylene acetabular component. J Bone Joint Surg Am. 1990;72:518. MEDLINE 25. 25Valdivia GG, Dunbar MJ, Parker DA, et al. Three-dimensional analysis of the cement mantle in total hip arthroplasty. Clin Orthop. 2001;393:38.
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26. 26Postel M, Kerboull M, Evrard J, et al. Total hip replacement. Berlin: Springer Verlag; 1987;. 27. 27Song Y, Goodman S, Jaffe R. An in-vitro study of femoral intramedullary pressures during hip replacement using modern cement technique. Clin Orthop. 1994;302:297. 28. 28Brown SA, Bargar WL. The influence of temperature and specimen size on the flexural properties of PMMA bone cement. J Biomed Mater Res. 1984;18:523. MEDLINE |
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29. 29Hertzler J, Miller MA, Mann KA. Fatigue crack growth rate does not depend on mantle thickness: an idealized cemented stem construct under torsional loading. J Orthop Res. 2002;20:676. MEDLINE |
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⁎ Department of Orthopaedics, Asahikawa Medical College, Asahikawa, Japan † Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Sapporo, Japan  Reprint requests: Hiroshi Ito, MD, Department of Orthopaedics, Asahikawa Medical College, Midorigaoka Higashi 2-1-1-1, Asahikawa 078-8510, Japan.
No benefits or funds were received in support of the study. PII: S0883-5403(06)00057-X doi:10.1016/j.arth.2006.01.016 © 2007 Elsevier Inc. All rights reserved. | |
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