JBJS | Evaluation of Periprosthetic Bone-Remodeling After Cementless Total Hip Arthroplasty : The Influence of the Extent of Porous Coating*

The Journal of Bone & Joint Surgery, Volume 82, Issue 10

Articles | October 01, 2000

Evaluation of Periprosthetic Bone-Remodeling After Cementless Total Hip Arthroplasty : The Influence of the Extent of Porous Coating*

Katsuyuki Yamaguchi, M.D.†; Kensaku Masuhara, M.D., Ph.D.‡; Kenji Ohzono, M.D., Ph.D.§; Nobuhiko Sugano, M.D., Ph.D.§; Takashi Nishii, M.D., Ph.D.§; Takahiro Ochi, M.D., Ph.D.§

View Disclosures and Other Information

Investigation performed at the Department of Orthopaedic Surgery, Osaka University Medical School, Suita, Japan
*No benefits in any form have been received or will be received 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 Orthopaedic Surgery, Kaizuka City Hospital, 3-10-20, Hori, Kaizuka, Osaka 597-0015, Japan.
‡Department of Orthopaedic Surgery, Osaka Koseinenkin Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka 553, Japan.
Â§Department of Orthopaedic Surgery, Osaka University Medical School, 2-2 Yamadaoka, Suita 565, Japan.

The Journal of Bone & Joint Surgery. 2000; 82:1426-1426

5 Recommendations (Recommend) | 3 Comments | Saved by 3 Users Save Case

text A A A

Abstract

Background: Total hip arthroplasty changes the levels of stress within the proximal part of the femur, and the femur remodels adjacent to the prosthesis. The stem size and the initial bone-mineral density around the distal portion of the stem affect postoperative bone-remodeling after the insertion of a fully porous-coated metal-cancellous prosthesis. The purpose of this study was to evaluate the influence of the extent of porous coating of this prosthesis on femoral bone-remodeling.

Methods: A longitudinal examination of sixty-one hips in fifty-four patients was performed. Thirty-one hips in twenty-seven patients with a fully porous-coated stem (Group A) and thirty hips in twenty-seven patients with a proximally porous-coated stem (Group B) were followed for twenty-four to thirty months. Periprosthetic bone-mineral density was measured with dual-energy x-ray absorptiometry at specific intervals after the operation.

Results: In both groups, the greatest loss of bone-mineral density, compared with the initial (three-week) value, was approximately 20 percent in zone 7 at twelve to eighteen months. In other zones, bone-remodeling appeared to cease by twelve months. At the last follow-up evaluation, the loss of bone-mineral density in the distal and middle regions in Group A was significantly greater than that in Group B (p < 0.01 for zone 3 and p < 0.05 for zone 6). In contrast, with the numbers available, there were no significant differences in loss of bone-mineral density in the proximal regions (zones 1 and 7) between the two groups at any follow-up period.

Conclusions: The extent of porous coating affects bone-remodeling in the distal periprosthetic region rather than in the proximal region. The results in the present report are specific to the particular implants that were studied.

Figures in this Article

Introduction

Introduction | Materials and Methods | Results | Discussion | References

Cementless total hip arthroplasty has been used widely since the 1980s. Although the clinical results of cementless total hip arthroplasties have been promising^6,8, proximal bone resorption around the femoral stem appears to be one of the major complications of the use of these implants^1,3,13,14. Progressive proximal femoral bone loss may reduce prosthetic stability and make revision difficult. Therefore, it is important to understand the remodeling that occurs around the femoral stem of a total hip arthroplasty.

We previously reported the bone-remodeling, as measured with dual-energy x-ray absorptiometry¹⁸, that occurred after insertion of a fully porous-coated stem. Most of the decrease in periprosthetic bone-mineral density ceased by twelve months postoperatively, and the stem size (Spearman correlation coefficient, r = -0.38; p < 0.05) and the initial bone-mineral density around the distal portion of the stem (Spearman correlation coefficient, r = 0.50; p < 0.01) were significantly associated with the decrease in proximal bone-mineral density. Kilgus et al.⁹ compared the change in periprosthetic bone-mineral density after implanting Anatomic Medullary Locking femoral components (DePuy, Warsaw, Indiana) of an identical design with varying amounts of porous coating in a cross-sectional study using dual-energy x-ray absorptiometry measurements. However, a longitudinal quantitative follow-up study of the effects of the extent of porous coating on periprosthetic bone-mineral density has not been reported to date, to our knowledge. The purpose of the present study was to evaluate those effects.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 1-A:: Figs. 1-A and 1-B: Photographs showing the metal-cancellous cementless Lübeck prosthesis.
Fig. 1-A: Photograph showing the metal socket, fully coated stem, interior polyethylene component, and alumina ceramic head.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 1-B:: Photograph showing the proximally coated stem. From left to right: anterior view, medial view, and lateral view.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 2:: Schematic drawings of the seven regions of interest around the fully coated stem (left) and the proximally coated stem (right), which resemble the zones described by Gruen et al.⁷.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 3:: Graph showing the initial average bone-mineral density (and standard deviation) at three weeks after the operation for both groups. The asterisks indicate a significant difference at p < 0.01. GZ = Gruen zone.

View Larger

TABLE I: Data on the Two Groups

*As determined with the Student t test.†As determined with the chi-square test.

	Group A (N = 31)	Group B (N = 30)	P Value
Mean age (range) at op. (yrs.)	56 (48 to 77)	58 (34 to 74)	0.353*
No. of men (no. of hips)	2 (2)	2 (2)	0.973†
No. of women (no. of hips)	25 (29)	25 (28)
Mean weight (range) (kg)	55 (39 to 73)	56 (45 to 79)	0.762*
No. of hips with osteoarthritis	28	29	0.317†
No. of hips with avascular necrosis	3	1

Add to My JBJS

TABLE I: Data on the Two Groups

*As determined with the Student t test.†As determined with the chi-square test.

	Group A (N = 31)	Group B (N = 30)	P Value
Mean age (range) at op. (yrs.)	56 (48 to 77)	58 (34 to 74)	0.353*
No. of men (no. of hips)	2 (2)	2 (2)	0.973†
No. of women (no. of hips)	25 (29)	25 (28)
Mean weight (range) (kg)	55 (39 to 73)	56 (45 to 79)	0.762*
No. of hips with osteoarthritis	28	29	0.317†
No. of hips with avascular necrosis	3	1

View Larger

TABLE II: Comparison of Postoperative Bone-Mineral-Density Ratios Between Groups A and B

*The values are expressed as the average percentage (and standard deviation) of the results.†The difference between the two groups was significant at p < 0.05.‡The difference between the two groups was significant at p < 0.01.

	Postoperative Period
3 Wks.	3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
No. of hips
Group A	31	19	29	30	22	25	23
Group B	30	16	24	29	29	27	27
Ratio*
Zone 1
Group A	100 ± 0	86.5 ± 21.8	84.6 ± 15.3	81.9 ± 24.1	88.3 ± 21.7	84.3 ± 18.4	84.1 ± 22.1
Group B	100 ± 0	89.7 ± 17.1	90.1 ± 14.9	87.7 ± 24.7	86.4 ± 24.8	87.9 ± 25.9	86.4 ± 20.8
Zone 2
Group A	100 ± 0	87.5 ± 11.3	89.0 ± 9.8†	87.9 ± 13.2	94.1 ± 6.9	91.3 ± 11.6	93.0 ± 12.9
Group B	100 ± 0	94.0 ± 11.2	96.5 ± 10.8†	92.0 ± 14.5	93.7 ± 14.9	94.1 ± 15.6	97.2 ± 13.8
Zone 3
Group A	100 ± 0	88.8 ± 8.5†	92.9 ± 11.7†	92.2 ± 9.6‡	94.1 ± 7.4†	92.1 ± 8.8‡	93.8 ± 10.2‡
Group B	100 ± 0	94.6 ± 8.0†	98.9 ± 7.9†	100.3 ± 9.5‡	99.7 ± 9.6†	100.8 ± 9.3‡	103.0 ± 8.7‡
Zone 4
Group A	100 ± 0	93.3 ± 13.7	92.8 ± 6.8	91.1 ± 7.6†	92.0 ± 6.9	91.9 ± 7.3	91.5 ± 9.6
Group B	100 ± 0	96.5 ± 6.7	96.5 ± 7.4	96.9 ± 11.4†	93.9 ± 9.8	95.8 ± 7.0	96.4 ± 9.0
Zone 5
Group A	100 ± 0	89.6 ± 10.6	91.7 ± 8.4‡	91.7 ± 13.1†	93.3 ± 10.6	93.6 ± 12.5	96.0 ± 14.8
Group B	100 ± 0	93.8 ± 8.8	98.3 ± 7.8‡	98.5 ± 8.7†	99.0 ± 10.3	100.0 ± 11.6	103.6 ± 12.1
Zone 6
Group A	100 ± 0	88.5 ± 11.5†	86.5 ± 9.0‡	85.5 ± 14.2‡	86.2 ± 12.2†	84.3 ± 10.8‡	86.5 ± 14.2†
Group B	100 ± 0	96.7 ± 10.7†	95.5 ± 10.5‡	94.7 ± 11.3‡	95.3 ± 15.5†	93.3 ± 12.3‡	96.0 ± 12.6†
Zone 7
Group A	100 ± 0	86.8 ± 13.3	78.8 ± 14.7	78.3 ± 13.8	78.8 ± 14.2	78.7 ± 16.8	78.8 ± 18.0
Group B	100 ± 0	85.5 ± 11.7	83.7 ± 11.6	82.4 ± 19.4	76.3 ± 19.6	77.3 ± 19.3	76.4 ± 18.4

Add to My JBJS

TABLE II: Comparison of Postoperative Bone-Mineral-Density Ratios Between Groups A and B

	Postoperative Period
3 Wks.	3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
No. of hips
Group A	31	19	29	30	22	25	23
Group B	30	16	24	29	29	27	27
Ratio*
Zone 1
Group A	100 ± 0	86.5 ± 21.8	84.6 ± 15.3	81.9 ± 24.1	88.3 ± 21.7	84.3 ± 18.4	84.1 ± 22.1
Group B	100 ± 0	89.7 ± 17.1	90.1 ± 14.9	87.7 ± 24.7	86.4 ± 24.8	87.9 ± 25.9	86.4 ± 20.8
Zone 2
Group A	100 ± 0	87.5 ± 11.3	89.0 ± 9.8†	87.9 ± 13.2	94.1 ± 6.9	91.3 ± 11.6	93.0 ± 12.9
Group B	100 ± 0	94.0 ± 11.2	96.5 ± 10.8†	92.0 ± 14.5	93.7 ± 14.9	94.1 ± 15.6	97.2 ± 13.8
Zone 3
Group A	100 ± 0	88.8 ± 8.5†	92.9 ± 11.7†	92.2 ± 9.6‡	94.1 ± 7.4†	92.1 ± 8.8‡	93.8 ± 10.2‡
Group B	100 ± 0	94.6 ± 8.0†	98.9 ± 7.9†	100.3 ± 9.5‡	99.7 ± 9.6†	100.8 ± 9.3‡	103.0 ± 8.7‡
Zone 4
Group A	100 ± 0	93.3 ± 13.7	92.8 ± 6.8	91.1 ± 7.6†	92.0 ± 6.9	91.9 ± 7.3	91.5 ± 9.6
Group B	100 ± 0	96.5 ± 6.7	96.5 ± 7.4	96.9 ± 11.4†	93.9 ± 9.8	95.8 ± 7.0	96.4 ± 9.0
Zone 5
Group A	100 ± 0	89.6 ± 10.6	91.7 ± 8.4‡	91.7 ± 13.1†	93.3 ± 10.6	93.6 ± 12.5	96.0 ± 14.8
Group B	100 ± 0	93.8 ± 8.8	98.3 ± 7.8‡	98.5 ± 8.7†	99.0 ± 10.3	100.0 ± 11.6	103.6 ± 12.1
Zone 6
Group A	100 ± 0	88.5 ± 11.5†	86.5 ± 9.0‡	85.5 ± 14.2‡	86.2 ± 12.2†	84.3 ± 10.8‡	86.5 ± 14.2†
Group B	100 ± 0	96.7 ± 10.7†	95.5 ± 10.5‡	94.7 ± 11.3‡	95.3 ± 15.5†	93.3 ± 12.3‡	96.0 ± 12.6†
Zone 7
Group A	100 ± 0	86.8 ± 13.3	78.8 ± 14.7	78.3 ± 13.8	78.8 ± 14.2	78.7 ± 16.8	78.8 ± 18.0
Group B	100 ± 0	85.5 ± 11.7	83.7 ± 11.6	82.4 ± 19.4	76.3 ± 19.6	77.3 ± 19.3	76.4 ± 18.4

View Larger

TABLE III: Statistical Comparison of Bone-Mineral-Density Ratios in Zones 1 and 7 Between the Two Groups at Each Follow-up Period

	Postoperative Period
3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
Zone 1	p = 0.637	p = 0.193	p = 0.365	p = 0.776	p = 0.569	p = 0.707
Zone 7	p = 0.763	p = 0.191	p = 0.355	p = 0.615	p = 0.782	p = 0.645

Add to My JBJS

TABLE III: Statistical Comparison of Bone-Mineral-Density Ratios in Zones 1 and 7 Between the Two Groups at Each Follow-up Period

	Postoperative Period
3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
Zone 1	p = 0.637	p = 0.193	p = 0.365	p = 0.776	p = 0.569	p = 0.707
Zone 7	p = 0.763	p = 0.191	p = 0.355	p = 0.615	p = 0.782	p = 0.645

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

The sixty-one hips in fifty-four patients in this study (Table I) had undergone total hip arthroplasty with a so-called metal-cancellous prosthesis^16,19,22. The criteria for inclusion were primary total hip arthroplasty, no radiographic signs of loosening, no perioperative complications, and no use of steroids after the index operation. Thirty-one hips in twenty-seven patients had a fully coated stem (Group A), and thirty hips in twenty-seven patients had a proximally coated stem (Group B). Patients who had had previous operative treatment of the femur were excluded from the study, with the exception of one patient in Group B who had undergone a combined intertrochanteric varus osteotomy and Chiari pelvic osteotomy. At the index total hip arthroplasty, no patient had a femoral fixation device, such as wire or screws, that can cause inaccurate measurement of periprosthetic bone-mineral density.

The hip system that was used consists of a metal socket and a curved-collared stem made of a cobalt-chromium-molybdenum alloy with a spongiosa metal structure (Anatomical Hip Endoprosthesis System Lübeck; S & G Implants, Lübeck, Germany), a polyethylene liner (PE-Kuroki interior component, S & G Implants), and a modular alumina ceramic head (Biolox; Feldmühle Aktiengesellschaft, Plochingen, Germany). The proximally coated stems have a circumferential porous layer on the proximal quarter of the lateral aspect and on two-thirds of the medial aspect. The curved-collared stem in the Lübeck system is anatomically matched to the medullary canal of the proximal part of the femur from nine to thirteen centimeters at one-centimeter intervals. The porous coating consists of spongiometal structure with a pore size ranging from 800 to 1500 micrometers (Fig. 1-A and Fig. 1-B).

The operation was performed through a posterolateral approach. Partial weight-bearing was started at one week postoperatively, and full weight-bearing was allowed at three weeks. The index scan was done at three weeks postoperatively to account for changes in bone-mineral density secondary to the operation. Subsequent follow-up measurements were made at three, six, twelve, eighteen, twenty-four, and thirty months, although all patients could not return for all scheduled examinations. The average duration of follow-up was twenty-eight months (range, twenty-four to thirty months) in Group A and twenty-nine months (range, twenty-four to thirty months) in Group B.

The patients were assessed clinically at the final follow-up evaluation with use of the Merle d'Aubignç?¡nd Postel hip score¹⁷. The stem canal filling ratio was calculated as the ratio of the diameter of the stem to that of the medullary canal of the femur at one centimeter distal to the lesser trochanter and at one centimeter proximal to the tip of the stem. The patients were placed supine on the scan table with standard knee and foot supports to place the femur in a neutral position. Several bags containing rice were placed around the patient's thigh to prevent the x-ray beam from scanning into air. The periprosthetic bone-mineral density was determined with dual-energy x-ray absorptiometry (DPX-L; Lunar, Madison, Wisconsin). The software (Orthopaedic Software Package, version 1.2; Lunar) was designed to measure the periprosthetic bone-mineral content and density in seven regions of interest based on the zones of Gruen et al.⁷ (Fig. 2). Scan resolution was 0.6 1.2 millimeters. The average scan time was seven minutes, and the average scan dose was 2.4 millirems. These values for the use of dual-energy x-ray absorptiometry in our study were comparable with those reported by other authors^10,12,21.

The bone-mineral-density ratio was calculated by dividing the bone-mineral density on each scan during the follow-up period by that in the corresponding zone at three weeks postoperatively and multiplying by 100. The difference in the bone-mineral-density ratio between the two groups was examined at each zone at each postoperative follow-up period with use of the Student t test. P values of less than 0.05 were considered to be significant.

Results

Introduction | Materials and Methods | Results | Discussion | References

At the final follow-up evaluation, the average Merle d'Aubignç??and Postel hip score¹⁷ in Group A was 17.2 points (range, 14 to 18 points). The scores for pain, mobility, and function in Group A averaged 5.9 points (5 or 6 points), 5.8 points (4, 5, or 6 points), and 5.5 points (4, 5, or 6 points), respectively. The average Merle d'Aubignç?¡nd Postel hip score in Group B was 17.0 points (range, 14 to 18 points). The scores for pain, mobility, and function in Group B averaged 5.8 points (5 or 6 points), 5.6 points (4, 5, or 6 points), and 5.5 points (4, 5, or 6 points), respectively. There was no significant difference, with the numbers available, between the two groups with regard to any clinical score. Stem subsidence of more than two millimeters was not seen, and no circumferential radiolucent lines were found around the stem.

In Group A, the average stem canal filling ratio was 86 percent (range, 71 to 100 percent) at one centimeter distal to the lesser trochanter and 90 percent (range, 71 to 100 percent) at one centimeter proximal to the stem tip. In Group B, the average ratio was 85 percent (range, 64 to 94 percent) at one centimeter distal to the lesser trochanter and 82 percent (range, 63 to 100 percent) at one centimeter proximal to the stem tip. There was no significant difference (p = 0.48), with the numbers available, in the average stem canal filling ratio at one centimeter distal to the lesser trochanter between the two groups, but the difference at one centimeter proximal to the stem tip was significantly different between the two groups (p < 0.001).

The stem sizes used for the patients in both groups ranged from ninety to 120 millimeters. With the numbers available, we could not detect a significant difference with respect to the stem size between the groups (p = 0.779, Mann-Whitney U test).

The precision error of the calculation by dual-energy x-ray absorptiometry was tested. Ten patients with a fully coated stem and ten patients with a proximally coated stem were scanned three times in succession. The patients were repositioned during each scan. The coefficient of variation was calculated as the standard deviation divided by the average multiplied by 100. The average coefficient of variation for the fully coated stems ranged from 1.3 percent in zone 4 to 2.8 percent in zone 2. That for the proximally coated stems ranged from 1.3 percent in zone 4 to 4.2 percent in zone 7.

At three weeks, there were no significant differences between the two groups with regard to the periprosthetic bone-mineral density in zones 1, 4, and 7 (p > 0.05 for each comparison), whereas the bone-mineral density in the other zones in Group B was significantly less than that in Group A (p < 0.01 for each comparison) (Fig. 3). There were significant differences between the two groups with regard to the bone-mineral-density ratios in zones 3 and 6 at three months; in zones 2, 3, 5, and 6 at six months; in zones 3, 4, 5, and 6 at twelve months; and in zones 3 and 6 at eighteen, twenty-four, and thirty months (p < 0.05 for each comparison) (Table II). No significant differences were found in the bone-mineral-density ratios in zones 1 and 7 at any follow-up period (p > 0.05 for each comparison) (Table III). In both groups, the greatest decrease in bone-mineral density (approximately 20 percent) was found in zone 7 at twelve to eighteen months. In other zones, bone-remodeling appeared to have stabilized by twelve months. After twenty-four months, there was little change in bone-mineral density in Group B in zones 3, 4, and 5, which represented the distal smooth surface of the proximally coated stem.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

Dual-energy x-ray absorptiometry is a precise method for quantifying bone mass and small changes in bone-mineral density around femoral implants after total hip arthroplasty. The reproducibility of our measurements was extremely high and was comparable with those reported by other authors^2,11,21. Kröger et al.¹¹ suggested that the best reference for bone-mineral density at the time of follow-up is the periprosthetic bone-mineral density of the involved side measured soon after the total hip arthroplasty. Therefore, we used the bone-mineral density at three weeks postoperatively for the reference baseline.

Some factors, such as gender, patient age, patient weight, stem size, stem canal filling ratio, and initial postoperative bone-mineral density, may affect the periprosthetic bone-mineral density postoperatively^3,4,10,14,24. In the present study, the male-female ratio, the average patient age and weight, the average stem size, and the average stem canal filling ratio at one centimeter distal to the lesser trochanter were closely matched in the two groups (p > 0.05 for each comparison). There was a significant difference between the two groups with regard to the stem canal filling ratio at one centimeter proximal to the stem tip (p < 0.001). However, the diameter at one centimeter proximal to the tip of the fully coated stem as calculated on the radiograph included the width of the porous coating. The thickness at the smooth surface of the proximally porous-coated stem is larger than the substrate thickness, except for the porous coating, of the identical portion of the fully coated stem. However, in this study, no significant association between the stem canal filling ratio at one centimeter proximal to the stem tip and the bone-mineral-density ratio at each Gruen zone at the last follow-up evaluation was found in either group. The difference of the stem canal filling ratio at one centimeter proximal to the stem tip in this study did not affect the comparison of the bone-mineral density ratio between the two groups. Therefore, except for the initial bone-mineral density at three weeks, the conditions in Group A and Group B were almost the same.

It has been reported that loss of bone-mineral density after cementless total hip arthroplasty is greater in femora with low initial bone-mineral density^4,14,24. However, in the present study, despite the significantly lower initial bone-mineral-density values in zones 2, 3, 5, and 6 in Group B, the loss of bone-mineral density as well as the proportional change in these regions was less in Group B than in Group A at the final follow-up evaluation.

Kilgus et al.⁹ reported a 34.8 percent decrease in bone-mineral density in the most proximal one centimeter of the medial femoral cortex and a 20 to 25 percent decrease in the next most proximal six centimeters of the medial femoral cortex at five to seven years after implantation of extensively porous-coated Anatomic Medullary Locking implants. Kiratli et al.¹⁰ reported that small decreases in bone-mineral density were seen up to eight years after implantation of cementless, press-fit femoral implants. Massari et al.¹⁵ reported 26.6 and 38.7 percent decreases in density in the medial metaphyseal region at nine months and eighteen months, respectively, after implantation of proximally hydroxyapatite-coated implants. However, in our study, the greatest decrease in bone-mineral density was about 20 percent, in zone 7 at twelve to eighteen months, and changes in bone-mineral density ceased by twelve months in the other zones in both groups. We speculate that the short stem length and the anatomical shape of the metal-cancellous cementless Lübeck prosthesis provide loading to a substantial area of the proximal part of the femur, which may be advantageous in terms of stress-shielding. In their study of Anatomic Medullary Locking implants, Kilgus et al. reported that 12.0-millimeter-diameter implants were associated with only slight decreases in bone-mineral density in comparison with controls that had not had an operation, but 13.5 and 15.0-millimeter-diameter implants were associated with significantly greater decreases (p Â£ 0.028, repeated-measures analysis of variance). The cylindrical diameter at one centimeter proximal to the tip of the prostheses in our study ranged from 8.0 to 12.0 millimeters. Therefore, the good results with regard to bone-remodeling may be due to the fact that the most commonly used stems in Japanese women had relatively small diameters and less stiffness.

Sumner et al.²³ reported on bone-remodeling around the proximal part of the femur at two years after implantation of a stem in a canine model. In the dogs with a fully coated stem, there was about a 15 to 20 percent loss of cortical area in regions adjacent to the porous coating. In contrast, in the dogs with a proximally coated stem, a similar degree of bone loss was observed proximally but there was less bone loss in the distal portions. Skinner et al.²⁰ reported that the length of porous coating had no effect on the state of stress in the proximal part of the femur. Furthermore, in their three-dimensional finite element analysis, differences of stress magnitudes between the proximally coated stem and the fully coated stem were prominent in the bone at the distal extent of the porous coating on the medial aspect of the stem (zone 6) and near the tip on the lateral aspect (zone 3). Our results demonstrated that bone-mineral-density ratios in zones 3 and 6 of the proximally coated stems were significantly larger than those of the fully coated stems after twenty-four months (p < 0.05 for each comparison), whereas, with the numbers available, no significant difference could be detected between the groups with regard to the bone-mineral-density ratios in zones 1 and 7 at any follow-up period (p > 0.05 for each comparison). Our results appear to be consistent with those in the described canine and three-dimensional finite element models.

The results of the present study are specific to the particular implants that we used. Differences in the amount of porous coating in different designs of femoral implants and differences with regard to shape, material, and porosity would have some effect on bone-remodeling. Longitudinal quantitative studies of different designs of femoral implants would be of value to evaluate in detail the influence of the extent of porous coating.

References

Introduction | Materials and Methods | Results | Discussion | References

Bobyn, J. D.; Mortimer, E. S.; Glassman, A. H.; Engh, C. A.; Miller, J. E.; and Brooks, C. E.: Producing and avoiding stress shielding. Laboratory and clinical observations of noncemented total hip arthroplasty. Clin. Orthop., 274: 79-96, 1992.

Cohen, B., and Rushton, N.: Accuracy of DEXA measurement of bone mineral density after total hip arthroplasty. J. Bone and Joint Surg., 77-B(3): 479-483, 1995.

Engh, C. A., and Bobyn, J. D.: The influence of stem size and extent of porous coating on femoral bone resorption after primary cementless hip arthroplasty. Clin. Orthop., 231: 7-28, 1988.

Engh, C. A.; McGovern, T. F.; Bobyn, J. D.; and Harris, W. H.: A quantitative evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. J. Bone and Joint Surg., 74-A: 1009-1020, Aug. 1992.

Engh, C. A.; O'Connor, D.; Jasty, M.; McGovern, T. F.; Bobyn, J. D.; and Harris, W. H.: Quantification of implant micromotion, strain shielding, and bone resorption with porous-coated anatomic medullary locking femoral prostheses. Clin. Orthop., 285: 13-29, 1992.

Engh, C. A., Jr.; Culpepper, W. J., II; and Engh, C. A.: Long-term results of use of the anatomic medullary locking prosthesis in total hip arthroplasty. J. Bone and Joint Surg., 79-A: 177-184, Feb. 1997.

Gruen, T. A.; McNeice, G. M.; and Amstutz, H. C.: "Modes of failure" of cemented stem-type femoral components: a radiographic analysis of loosening. Clin. Orthop., 141: 17-27, 1979.

Heekin, R. D.; Callaghan, J. J.; Hopkinson, W. J.; Savory, C. G.; and Xenos, J. S.: The porous-coated anatomic total hip prosthesis, inserted without cement. Results after five to seven years in a prospective study. J. Bone and Joint Surg., 75-A: 77-91, Jan. 1993.

Kilgus, D. J.; Shimaoka, E. E.; Tipton, J. S.; and Eberle, R. W.: Dual-energy x-ray absorptiometry measurement of bone mineral density around porous-coated cementless femoral implants. Methods and preliminary results. J. Bone and Joint Surg., 75-B(2): 279-287, 1993.

Kiratli, B. J.; Checovich, M. M.; McBeath, A. A.; Wilson, M. A.; and Heiner, J. P.: Measurement of bone mineral density by dual-energy x-ray absorptiometry in patients with the Wisconsin hip, an uncemented femoral stem. J. Arthroplasty, 11: 184-193, 1996.

Kröger, H.; Miettinen, H.; Arnala, I.; Koski, E.; Rushton, N.; and Suomalainen, O.: Evaluation of periprosthetic bone using dual-energy x-ray absorptiometry: precision of the method and effect of operation on bone mineral density. J. Bone and Min. Res., 11: 1526-1530, 1996.

Kröger, H.; Venesmaa, P.; Jurvelin, J.; Miettinen, H.; Suomalainen, O.; and Alhava, E.: Bone density at the proximal femur after total hip arthroplasty. Clin. Orthop., 352: 66-74, 1998.

Lord, G.; Marotte, J. H.; Blanchard, J. P.; Guillamon, J. L.; Servant, J.; Samuel, P.; and Gentaz, R.: Cementless Madreporic and polarised total hip prostheses. A ten-year review of 2688 cases. French J. Orthop. Surg., 2: 82-92, 1988.

Maloney, W. J.; Sychterz, C.; Bragdon, C.; McGovern, T.; Jasty, M.; Engh, C. A.; and Harris, W. H.: Skeletal response to well fixed femoral components inserted with and without cement. Clin. Orthop., 333: 15-26, 1996.

Massari, L.; Bagni, B.; Biscione, R.; and Traina, G. C.: Periprosthetic bone density in uncemented femoral hip implants with proximal hydroxyapatite coating. Bull. Hosp. Joint Dis., 54: 206-210, 1996.

Matsui, M.; Nakata, K.; Masuhara, K.; Ohzono, K.; Sugano, N.; and Ochi, T.: The Metal-Cancellous Cementless Lübeck total hip arthroplasty. Five-to-nine-year results. J. Bone and Joint Surg., 80-B(5): 404-410, 1998.

Merle d'Aubignçª R., and Postel, M.: Functional results of hip arthroplasty with acrylic prosthesis. J. Bone and Joint Surg., 36-A: 451-475, June 1954.

Nishii, T.; Sugano, N.; Masuhara, K.; Shibuya, T.; Ochi, T.; and Tamura, S.: Longitudinal evaluation of time related bone remodeling after cementless total hip arthroplasty. Clin. Orthop., 339: 121-131, 1997.

Plötz, W.; Gradinger, R.; Rechl, H.; Ascherl, R.; Wicke-Wittenius, S.; and Hipp, E.: Cementless prosthesis of the hip joint with "spongy metal" surface. A prospective study. Arch. Orthop. and Trauma Surg., 111: 102-109, 1992.

Skinner, H. B.; Kim, A. S.; Keyak, J. H.; and Mote, C. D., Jr.: Femoral prosthesis implantation induces changes in bone stress that depend on the extent of porous coating. J. Orthop. Res., 12: 553-563, 1994.

Smart, R. C.; Barbagallo, S.; Slater, G. L.; Kuo, R. S.; Butler, S. P.; Drummond, R. P.; and Sekel, R.: Measurement of periprosthetic bone density in hip arthroplasty using dual-energy x-ray absorptiometry. J. Arthroplasty, 11: 445-452, 1996.

Sugano, N.; Saito, S.; Takaoka, K.; Ohzono, K.; Masuhara, K.; Saito, M.; and Ono, K.: Spongy metal Lübeck hip prostheses for osteoarthritis secondary to hip dysplasia. A 2-6-year follow-up study. J. Arthroplasty, 9: 253-262, 1994.

Sumner, D. R.; Turner, T. M.; Urban, R. M.; and Galante, J. O.: Bone remodeling 2 years after cementless THA with a proximally porous-coated stem. Trans. Orthop. Res. Soc., 15: 207, 1990.

Sychterz, C. J., and Engh, C. A.: The influence of clinical factors on periprosthetic bone remodeling. Clin. Orthop., 322: 285-292, 1996.

Topics

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 1-B:: Photograph showing the proximally coated stem. From left to right: anterior view, medial view, and lateral view.

View Large | Download Slide(.ppt)
Add to My JBJS

Fig. 2:: Schematic drawings of the seven regions of interest around the fully coated stem (left) and the proximally coated stem (right), which resemble the zones described by Gruen et al.⁷.

View Large | Download Slide(.ppt)
Add to My JBJS

View Larger

TABLE I: Data on the Two Groups

*As determined with the Student t test.†As determined with the chi-square test.

	Group A (N = 31)	Group B (N = 30)	P Value
Mean age (range) at op. (yrs.)	56 (48 to 77)	58 (34 to 74)	0.353*
No. of men (no. of hips)	2 (2)	2 (2)	0.973†
No. of women (no. of hips)	25 (29)	25 (28)
Mean weight (range) (kg)	55 (39 to 73)	56 (45 to 79)	0.762*
No. of hips with osteoarthritis	28	29	0.317†
No. of hips with avascular necrosis	3	1

Add to My JBJS

TABLE I: Data on the Two Groups

*As determined with the Student t test.†As determined with the chi-square test.

	Group A (N = 31)	Group B (N = 30)	P Value
Mean age (range) at op. (yrs.)	56 (48 to 77)	58 (34 to 74)	0.353*
No. of men (no. of hips)	2 (2)	2 (2)	0.973†
No. of women (no. of hips)	25 (29)	25 (28)
Mean weight (range) (kg)	55 (39 to 73)	56 (45 to 79)	0.762*
No. of hips with osteoarthritis	28	29	0.317†
No. of hips with avascular necrosis	3	1

View Larger

TABLE II: Comparison of Postoperative Bone-Mineral-Density Ratios Between Groups A and B

	Postoperative Period
3 Wks.	3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
No. of hips
Group A	31	19	29	30	22	25	23
Group B	30	16	24	29	29	27	27
Ratio*
Zone 1
Group A	100 ± 0	86.5 ± 21.8	84.6 ± 15.3	81.9 ± 24.1	88.3 ± 21.7	84.3 ± 18.4	84.1 ± 22.1
Group B	100 ± 0	89.7 ± 17.1	90.1 ± 14.9	87.7 ± 24.7	86.4 ± 24.8	87.9 ± 25.9	86.4 ± 20.8
Zone 2
Group A	100 ± 0	87.5 ± 11.3	89.0 ± 9.8†	87.9 ± 13.2	94.1 ± 6.9	91.3 ± 11.6	93.0 ± 12.9
Group B	100 ± 0	94.0 ± 11.2	96.5 ± 10.8†	92.0 ± 14.5	93.7 ± 14.9	94.1 ± 15.6	97.2 ± 13.8
Zone 3
Group A	100 ± 0	88.8 ± 8.5†	92.9 ± 11.7†	92.2 ± 9.6‡	94.1 ± 7.4†	92.1 ± 8.8‡	93.8 ± 10.2‡
Group B	100 ± 0	94.6 ± 8.0†	98.9 ± 7.9†	100.3 ± 9.5‡	99.7 ± 9.6†	100.8 ± 9.3‡	103.0 ± 8.7‡
Zone 4
Group A	100 ± 0	93.3 ± 13.7	92.8 ± 6.8	91.1 ± 7.6†	92.0 ± 6.9	91.9 ± 7.3	91.5 ± 9.6
Group B	100 ± 0	96.5 ± 6.7	96.5 ± 7.4	96.9 ± 11.4†	93.9 ± 9.8	95.8 ± 7.0	96.4 ± 9.0
Zone 5
Group A	100 ± 0	89.6 ± 10.6	91.7 ± 8.4‡	91.7 ± 13.1†	93.3 ± 10.6	93.6 ± 12.5	96.0 ± 14.8
Group B	100 ± 0	93.8 ± 8.8	98.3 ± 7.8‡	98.5 ± 8.7†	99.0 ± 10.3	100.0 ± 11.6	103.6 ± 12.1
Zone 6
Group A	100 ± 0	88.5 ± 11.5†	86.5 ± 9.0‡	85.5 ± 14.2‡	86.2 ± 12.2†	84.3 ± 10.8‡	86.5 ± 14.2†
Group B	100 ± 0	96.7 ± 10.7†	95.5 ± 10.5‡	94.7 ± 11.3‡	95.3 ± 15.5†	93.3 ± 12.3‡	96.0 ± 12.6†
Zone 7
Group A	100 ± 0	86.8 ± 13.3	78.8 ± 14.7	78.3 ± 13.8	78.8 ± 14.2	78.7 ± 16.8	78.8 ± 18.0
Group B	100 ± 0	85.5 ± 11.7	83.7 ± 11.6	82.4 ± 19.4	76.3 ± 19.6	77.3 ± 19.3	76.4 ± 18.4

Add to My JBJS

TABLE II: Comparison of Postoperative Bone-Mineral-Density Ratios Between Groups A and B

	Postoperative Period
3 Wks.	3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
No. of hips
Group A	31	19	29	30	22	25	23
Group B	30	16	24	29	29	27	27
Ratio*
Zone 1
Group A	100 ± 0	86.5 ± 21.8	84.6 ± 15.3	81.9 ± 24.1	88.3 ± 21.7	84.3 ± 18.4	84.1 ± 22.1
Group B	100 ± 0	89.7 ± 17.1	90.1 ± 14.9	87.7 ± 24.7	86.4 ± 24.8	87.9 ± 25.9	86.4 ± 20.8
Zone 2
Group A	100 ± 0	87.5 ± 11.3	89.0 ± 9.8†	87.9 ± 13.2	94.1 ± 6.9	91.3 ± 11.6	93.0 ± 12.9
Group B	100 ± 0	94.0 ± 11.2	96.5 ± 10.8†	92.0 ± 14.5	93.7 ± 14.9	94.1 ± 15.6	97.2 ± 13.8
Zone 3
Group A	100 ± 0	88.8 ± 8.5†	92.9 ± 11.7†	92.2 ± 9.6‡	94.1 ± 7.4†	92.1 ± 8.8‡	93.8 ± 10.2‡
Group B	100 ± 0	94.6 ± 8.0†	98.9 ± 7.9†	100.3 ± 9.5‡	99.7 ± 9.6†	100.8 ± 9.3‡	103.0 ± 8.7‡
Zone 4
Group A	100 ± 0	93.3 ± 13.7	92.8 ± 6.8	91.1 ± 7.6†	92.0 ± 6.9	91.9 ± 7.3	91.5 ± 9.6
Group B	100 ± 0	96.5 ± 6.7	96.5 ± 7.4	96.9 ± 11.4†	93.9 ± 9.8	95.8 ± 7.0	96.4 ± 9.0
Zone 5
Group A	100 ± 0	89.6 ± 10.6	91.7 ± 8.4‡	91.7 ± 13.1†	93.3 ± 10.6	93.6 ± 12.5	96.0 ± 14.8
Group B	100 ± 0	93.8 ± 8.8	98.3 ± 7.8‡	98.5 ± 8.7†	99.0 ± 10.3	100.0 ± 11.6	103.6 ± 12.1
Zone 6
Group A	100 ± 0	88.5 ± 11.5†	86.5 ± 9.0‡	85.5 ± 14.2‡	86.2 ± 12.2†	84.3 ± 10.8‡	86.5 ± 14.2†
Group B	100 ± 0	96.7 ± 10.7†	95.5 ± 10.5‡	94.7 ± 11.3‡	95.3 ± 15.5†	93.3 ± 12.3‡	96.0 ± 12.6†
Zone 7
Group A	100 ± 0	86.8 ± 13.3	78.8 ± 14.7	78.3 ± 13.8	78.8 ± 14.2	78.7 ± 16.8	78.8 ± 18.0
Group B	100 ± 0	85.5 ± 11.7	83.7 ± 11.6	82.4 ± 19.4	76.3 ± 19.6	77.3 ± 19.3	76.4 ± 18.4

View Larger

TABLE III: Statistical Comparison of Bone-Mineral-Density Ratios in Zones 1 and 7 Between the Two Groups at Each Follow-up Period

	Postoperative Period
3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
Zone 1	p = 0.637	p = 0.193	p = 0.365	p = 0.776	p = 0.569	p = 0.707
Zone 7	p = 0.763	p = 0.191	p = 0.355	p = 0.615	p = 0.782	p = 0.645

Add to My JBJS

TABLE III: Statistical Comparison of Bone-Mineral-Density Ratios in Zones 1 and 7 Between the Two Groups at Each Follow-up Period

	Postoperative Period
3 Mos.	6 Mos.	12 Mos.	18 Mos.	24 Mos.	30 Mos.
Zone 1	p = 0.637	p = 0.193	p = 0.365	p = 0.776	p = 0.569	p = 0.707
Zone 7	p = 0.763	p = 0.191	p = 0.355	p = 0.615	p = 0.782	p = 0.645

Cohen, B., and Rushton, N.: Accuracy of DEXA measurement of bone mineral density after total hip arthroplasty. J. Bone and Joint Surg., 77-B(3): 479-483, 1995.

Engh, C. A., and Bobyn, J. D.: The influence of stem size and extent of porous coating on femoral bone resorption after primary cementless hip arthroplasty. Clin. Orthop., 231: 7-28, 1988.

Gruen, T. A.; McNeice, G. M.; and Amstutz, H. C.: "Modes of failure" of cemented stem-type femoral components: a radiographic analysis of loosening. Clin. Orthop., 141: 17-27, 1979.

Kröger, H.; Venesmaa, P.; Jurvelin, J.; Miettinen, H.; Suomalainen, O.; and Alhava, E.: Bone density at the proximal femur after total hip arthroplasty. Clin. Orthop., 352: 66-74, 1998.

Merle d'Aubignçª R., and Postel, M.: Functional results of hip arthroplasty with acrylic prosthesis. J. Bone and Joint Surg., 36-A: 451-475, June 1954.

Sumner, D. R.; Turner, T. M.; Urban, R. M.; and Galante, J. O.: Bone remodeling 2 years after cementless THA with a proximally porous-coated stem. Trans. Orthop. Res. Soc., 15: 207, 1990.

Sychterz, C. J., and Engh, C. A.: The influence of clinical factors on periprosthetic bone remodeling. Clin. Orthop., 322: 285-292, 1996.

Accreditation Statement

These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.

CME Activities Associated with This Article

Submit a Comment

Please read the other comments before you post yours. Contributors must reveal any conflict of interest.
Comments are moderated and will appear on the site at the discretion of JBJS editorial staff.

* = Required Field

Comment Author(s) * (if multiple authors, separate names by comma)

Example: John Doe

Affiliation & Institution*

Comment Title*

Comment*

Cancel

Print
PDF
Email

Recipient(s) will receive an email with a link (good for 5 Days) to 'Evaluation of Periprosthetic Bone-Remodeling After Cementless Total Hip Arthroplasty : The Influence of the Extent of Porous Coating*' and do not need to have The Journal of Bone & Joint Surgery account to access the content.
Your Name:*
Example: John Doe

Email Address:* CC Me:
Enter your valid email address. Example: jdoe@example.com

Recipient's Email Address:*

Separate multiple email address with semi-colons (up to 5).

Subject:* 's The Journal of Bone & Joint Surgery: 'Evaluation of Periprosthetic Bone-Remodeling After Cementless Total Hip Arthroplasty : The Influence of the Extent of Porous Coating*'
Subject for your email.

Message:

(Optional, message will truncate at 1000 characters)

Processing your request... Please Wait...

Copyright © in the material you requested is held by The Journal of Bone & Joint Surgery, Inc. (unless otherwise noted). This email ability is provided as a courtesy, and by using it you agree that that you are requesting the material solely for personal, non-commercial use, and that it is subject to Journal of Bone & Joint Surgery, Inc.'s Terms of Use. The information provided in order to email this topic will not be used to send unsolicited email, nor will it be furnished to third parties. Please refer to The Journal of Bone & Joint Surgery Inc.'s Privacy Policy for further information.

Copyright © The Journal of Bone & Joint Surgery Inc. All rights reserved.
Share
Get Citation

Katsuyuki Yamaguchi, Kensaku Masuhara, Kenji Ohzono, Nobuhiko Sugano, Takashi Nishii, Takahiro Ochi; Evaluation of Periprosthetic Bone-Remodeling After Cementless Total Hip Arthroplasty The Influence of the Extent of Porous Coating*. The Journal of Bone & Joint Surgery. 2000 Oct;82(10):1426-1426.

Download citation file:

RIS (Zotero)

EndNote

BibTex

Medlars

ProCite

RefWorks

Reference Manager

Copyright © The Journal of Bone and Joint Surgery, Inc.
Rights & Permissions
Sign Up for Alerts on this
Article

Processing your request... Please Wait.
Submit a Comment