地舒单抗对绝经后骨质疏松性股骨颈骨折全髋关节置换术后股骨近端假体周围骨密度的影响

目的:研究地舒单抗对绝经后骨质疏松性股骨颈骨折患者全髋关节置换术后(total hip arthroplasty,THA)股骨近端假体周围骨密度的影响。方法:选取2020年10月至2021年10月绝经后女性骨质疏松性股骨颈骨折行THA术后54例,治疗组25例接受地舒单抗治疗,年龄(74.3±6.2)岁;对照组29例未接受地舒单抗治疗,年龄(75.2±4.8)岁。术后1周及3、6及12个月各个时间点,通过双能X线骨密度仪(DEXA型)测定股骨近端假体周围骨密度,并在不同时间点测量骨转换各项指标。结果:术后3、6及12个月对照组的抗酒石酸酸性磷酸酶(tartrate resistant acid phosphatase,TRACP-5b)高于治疗组(P<0.05);对照组术后12个月骨特异性碱性磷酸酶(bone-specific alkaline phosphatase,BALP)高于治疗组(P<0.05)。两组患者Gruen 1、7区的骨密度在术后3、6及12个月较术后1周(基线)均下降(P<0.05);对照组Gruen 7区术后各时间点比较,差异有统计学意义(P<0.05);治疗组各时间点比较,差异无统计学意义(P>0.05)。两组术后3个月Gruen 1、7区比较,差异无统计学意义(P>0.05);术后6个月Gruen 1、7区和术后12个月Gruen 1、7区,治疗组骨密度均明显高于对照组(P<0.05)。两组术后3个月Gruen 1、7区骨密度下降百分比比较,差异无统计学意义(P>0.05)。对照组术后6个月Gruen 1、7区,术后12个月Gruen 1、7区骨密度下降百分比明显高于治疗组(P<0.05)。提示在使用地舒单抗6个月后,即可降低骨密度丢失幅度,并且该效应可达至术后12个月。结论:绝经后骨质疏松性股骨颈骨折患者在THA术后,使用地舒单抗可减少股骨近端假体周围骨密度丢失,有效抑制骨吸收。     

Bone loss around failed femoral implant measured by dual-energy X-ray absorptiometry

Periprosthetic bone mineral density (BMD) and its changes after primary total hip arthroplasty (THA) have been studied extensively, but quantitative data on BMD around loosened prostheses are still lacking. In this study, using dual-energy X-ray absorptiometry (DXA), we determined periprosthetic BMD in 19 patients with failed primary THA. There was a decrease in BMD (8.8%–25.5%) in every Gruen zone as compared with the patient's non-operated (control) side. Although the bone loss was most significant in the proximal femur, as in primary THA, the pattern of bone loss around the failed THA differred from the typical remodeling seen after successful THA. We suggest that quantitation of bone mass around the failed femoral stem is possible. Remarkable generalized bone loss around the stem is associated with a loosened prosthesis. Received: November 12, 1999 / Accepted: December 24, 1999     

Female patients with low systemic BMD are prone to bone loss in Gruen zone 7 after cementless total hip arthroplasty: A 2-year DXA follow-up of 39 patients

Background and purpose Factors that lead to periprosthetic bone loss following total hip arthroplasty (THA) may not only depend on biomechanical implant-related factors, but also on various patient-related factors. We investigated the association between early changes in periprosthetic bone mineral density (BMD) and patient-related factors.Patients and methods 39 female patients underwent cementless THA (ABG II) with ceramic-ceramic bearing surfaces. Periprosthetic BMD in the proximal femur was determined with DXA after surgery and at 3, 6, 12, and 24 months. 27 patient-related factors were analyzed for their value in prediction of periprosthetic bone loss.Results Total periprosthetic BMD was temporarily reduced by 3.7% at 3 months (p < 0.001), by 3.8% at 6 months (p < 0.01), and by 2.6% at 12 months (p < 0.01), but recovered thereafter up to 24 months. Preoperative systemic osteopenia and osteoporosis, but not the local BMD of the operated hip, was predictive of bone loss in Gruen zone 7 (p = 0.04), which was the only region with a statistically significant decrease in BMD (23%, p < 0.001) at 24 months. Preoperative serum markers of bone turnover predicted the early temporary changes of periprosthetic BMD. The other patient-related factors failed to show any association with the periprosthetic BMD changes.Interpretation Female patients with low systemic BMD show greater bone loss in Gruen zone 7 after cementless THA than patients with normal BMD. Systemic DXA screening for osteoporosis in postmenopausal patients before THA could be used to identify patients in need of prophylactic anti-resorptive therapy.     

Monitoring of periprosthetic BMD after uncemented total hip arthroplasty with dual-energy X-ray absorptiometry--a 3-year follow-up study.

Insertion of a metallic implant into the femur changes bone loading conditions and results in remodeling of femoral bone. To quantify changes in bone mass after uncemented total hip arthroplasty (THA), we monitored femoral bone with dual-energy X-ray absorptiometry (DXA). The periprosthetic bone mineral density (BMD) was measured with Lunar DPX densitometry in seven Gruen zones and the total periprosthetic area at scheduled time intervals in 22 patients during a 3-year follow-up. BMD decreased significantly almost in all Gruen zones during the first 3 months, ranging from 3.4% to 14.4% (p < 0.05 top < 0.001). At the end of the first year, the most remarkable decrease in BMD was found in the calcar (zone 7; -22.9%). During the second postoperative year, a slight restoration of periprosthetic bone mass was recorded. During the third year, no significant changes in BMD were found. The preoperative BMD was the only factor that was significantly related to the periprosthetic bone loss. Clearly, the early periprosthetic bone loss noticed during the 3 months after THA is caused by mainly limited weight bearing to the operated hip and stress shielding. We suggest that the restoration of bone mass is a sign of successful osteointegration between bone and metallic implant. DXA is a suitable tool to follow the bone response to prosthetization and will increase our knowledge on the behavior of bone after THA.     

Periprosthetic bone loss after cemented total hip arthroplasty

In this prospective 5-year study, we determined the periprosthetic bone loss after cemented total hip arthroplasty (THA) in 15 patients using dual energy X-ray absorptiometry (DXA). A reduction in the periprosthetic bone mineral density (BMD) of 5-18% occurred in all Gruen regions, or regions of interest (ROI), during the first 3 months after THA. The bone loss continued up to 6 months in almost all ROIs. From 1 to 5 years, we found only minor changes in BMD in periprosthetic bone. After the follow-up, the mean greatest bone loss (26%) was seen in the femoral calcar area. The reduction in mean BMD was 5% in men, and 16% in women. The lower the preoperative BMD, the higher was the postoperative bone loss. We found that after the phase of acute bone loss, further loss was minimal, reflecting merely the normal ageing of bone after uncomplicated THA.     

Changes of femoral periprosthetic bone mineral density 6 years after treatment with alendronate following total hip arthroplasty

Earlier osteodensitometric results of femoral periprosthetic bone showed that postoperative antiresorptive treatment with alendronate following total hip arthroplasty (THA) reduces the periprosthetic bone loss that commonly occurs in the first months after surgery. However, whether alendronate can prevent periprosthetic bone loss over the long term, or if bone loss occurs after discontinuing alendronate is unknown. Femoral periprosthetic bone mineral density (BMD) was assessed in 49 patients 6 years after cementless total hip arthroplasty using dual energy X‐ray absorptiometry. Twenty‐nine patients were treated postoperatively with alendronate and 20 control patients received no treatment. All patients were followed up at 12 months after surgery in a prospective randomized study. The bone mineral density was evaluated in 7 regions of interest according to the Gruen protocol. Six years after total hip arthroplasty, no significant changes were detected in femoral periprosthetic BMD when compared with results at 1 year, and the bone loss in patients with postoperative alendronate treatment was still significantly less than those without treatment. These results suggest that the prevention of femoral periprosthetic bone loss following THA achieved by postoperative antiresorptive treatment with alendronate is of long‐standing effect, and further bone loss does not occur after the first postoperative year. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:183–188, 2009     

Periprosthetic bone loss after cemented total hip arthroplasty: a prospective 5-year dual energy radiographic absorptiometry study of 15 patients

In this prospective 5-year study, we determined the periprosthetic bone loss after cemented total hip arthroplasty (THA) in 15 patients using dual energy X-ray absorptiometry (DXA). A reduction in the periprosthetic bone mineral density (BMD) of 5-18% occurred in all Gruen regions, or regions of interest (ROI), during the first 3 months after THA. The bone loss continued up to 6 months in almost all ROIs. From 1 to 5 years, we found only minor changes in BMD in periprosthetic bone. After the follow-up, the mean greatest bone loss (26%) was seen in the femoral calcar area. The reduction in mean BMD was 5% in men, and 16% in women. The lower the preoperative BMD, the higher was the postoperative bone loss. We found that after the phase of acute bone loss, further loss was minimal, reflecting merely the normal ageing of bone after uncomplicated THA.     

Comparison of periprosthetic bone remodelling after implantation of anatomic and straight stem prostheses in total hip arthroplasty

Introduction Total hip arthroplasty changes bone loading conditions in the proximal femur and induces adaptive remodelling of the periprosthetic bone. These remodelling processes depend on many implant-specific qualities, e.g. material and elasticity of the stem. The objective of this study was to investigate the effect of the stem design on periprosthetic bone remodelling after insertion of an anatomic stem with proximal fixation and the direct comparison to a straight stem prosthesis. Materials and methods In a prospective study, the changes in periprosthetic bone mineral density (BMD) after implantation of 68 CTX-S anatomic and 22 PPF straight stem prostheses were assessed in the first post-operative year by means of DEXA and zone analysis by Gruen (Clin Orthop 141:17–27, 1979) “Modes of failure” of cemented stem-type femoral components: a radiographic analysis of loosening.. Furthermore all patients with CTX-S prostheses were monitored in the second post-operative year. The correlation of adaptive bone remodelling and the systemic bone density was also investigated. Results In the distal one-third of the straight stem prosthesis, a clearly greater, although not significant, hypertrophy of the periprosthetic bone was observed. No differences in the extent of bone loss between the two prostheses in the regions of interest (ROI) of the proximal bone were observed. The greatest decrease in BMD was registered in the medial femoral neck in both groups. Bone atrophy decreased progressively as the ROI moved distally, ending in a slight increase in BMD in the distal ROI. No significant changes in periprosthetic BMD occurred in the second post-operative year. A strong positive correlation in the regions with the greatest BMD decrease with the systemic BMD was ascertained. Conclusion After implanting a CTX-S prosthesis, as opposed to PPF prostheses, a different pattern of periprosthetic bone remodelling with a slighter hypertrophy of the distal periprosthetic parts was observed. This implies that the extensive proximal, more physiological bone loading of the anatomic stem as well as the removal of less bone while implanting the stem reduces the negative effects of unphysiological strain distribution and stress shielding. The BMD loss in the medial proximal neck cannot be avoided with this stem design either. The lack of significant BMD changes in the second post-operative year suggests that a stabilisation of bone remodelling processes occurs.     

Bone mineral density and biochemical markers of bone turnover in aseptic loosening after total hip arthroplasty.

The aims of this study were to determine whether subjects with aseptic loosening after total hip arthroplasty (THA) have regional differences in periprosthetic bone mineral density (BMD) and systemic biochemical markers of bone turnover compared to subjects with successful implants.Proximal femoral and pelvic BMD were measured by dual energy X-ray absorptiometry and bone turnover markers were assayed in 49 subjects 12.6+/-4.3 (mean+/-SD) years after cemented THA. Femoral BMD was lower in Gruen zones 2, 5, 6, and 7 in subjects with a loose femoral implant (n=17) compared to those (n=32) with fixed femoral implants (P<0.05 all comparisons). This BMD difference was greatest (-31%, P=0.02) in the proximal and medial region of the femur. Subjects with femoral loosening had higher levels of the bone resorption marker N-telopeptides of type-I collagen (P=0.02) than those with a fixed femoral implant. No differences in pelvic BMD or bone turnover markers were found between subjects with loose (n=18) versus fixed (n=31) pelvic implants.This study suggests that failure of femoral components after cemented THA is associated with region-specific decreases in BMD and an increase in urinary excretion of N-telopeptide cross-links of type-I collagen. These surrogate outcome markers may be of value in monitoring response to antiresorptive therapies used to treat periprosthetic osteolysis, although the diagnosis of aseptic loosening remains clinical and radiological.     

唑来膦酸对骨质疏松患者全髋关节置换术后假体周围骨密度的影响

目的：探讨注射用唑来膦酸5 mg对骨质疏松患者全髋关节置换术后假体周围骨密度的影响。方法选取2012年3月至2013年2月期间因骨质疏松性髋部骨折行全髋关节置换术的患者31例,所有患者初次诊断均为原发性骨质疏松症合并髋部骨折,入院前未曾行任何抗骨质疏松治疗,根据随机数字表分为两组：治疗组（16例,平均年龄73.8岁）,全髋关节置换术后5～7 d给予唑来膦酸5 mg,静脉滴注30 min,同时口服钙尔奇600 mg/d及阿尔法D30.25 ug/d;对照组（15例,平均年龄74.1岁）,术后仅给予口服钙尔奇600 mg/d及阿尔法D30.25 ug/d。分别于术后1周、3个月、6个月、12个月使用双能X线骨密度仪（ DEXA）测定两组患者假体周围各感兴趣区的骨密度值。结果两组患者术后3个月、6个月、12个月与术后1周（基线）股骨近端假体周围骨密度除Gruen1区外,2～7区骨密度均呈不同程度下降。治疗组与对照组骨密度变化值相比,术后3个月Gruen 4区（0.84％vs -3.34％, t＝3.5805）、7区（-3.61％vs -16.7, t＝4.0455）组间差异有统计学意义（P＜0.05）;术后6个月Gruen 1区（9.96％vs 1.17％, t＝2.1293）、4区（1.21 vs -2.96, t＝2.0892）、6区（-0.56 vs -6.16, t＝2.9500）、7区（-5.71 vs -22.8, t＝4.3959）组间差异有统计学意义（ P＜0.05）;术后12个月Gruen 1区（13.83 vs 1.39, t＝2.1795）、4区（0.81 vs -3.68, t＝2.1805）、6区（0.14 vs -6.04, t＝0.0247）、7区（-8.39 vs -25.4, t ＝3.8959）组间差异有统计学意义（ P＜0.05）。术后使用唑来膦酸3个月即表现出明显抑制骨量丢失的作用,并且于6个月、12个月时唑来膦酸对Gruen 1、4、6、7区骨量有持续的正向影响;Gruen 7个区中对1、7区的影响最大,治疗组1区骨密度增幅是对照组的9.95倍,7区骨密度减幅是对照组的1/3。结论唑来膦酸注射液5 mg能有效减少股骨假体周围骨密度的丢失,潜在的增加假体生物学稳定性,减少假体无菌性松动的概率,延长假体使用寿命。     

Periprosthetic bone mineral density with a cementless triple tapered stem is dependent on daily activity

Purpose

Periprosthetic bone loss around the femoral stem is frequently found after total hip arthroplasty. We have shown that periprosthetic bone mineral density (BMD) loss using the triple tapered stem is consistently much less in comparison with the straight type component. In this study, we compared periprosthetic BMD change with clinical factors.

Methods

Postoperative dual-energy X-ray absorptiometry was evaluated at follow-up. BMD was determined based on seven Gruen zones. We further compared BMD with clinical examination: body mass index (BMI), age, Harris hip score (HHS) or University of California at Los Angeles (UCLA) activity rating score.

Results

Periprosthetic BMD loss of the triple tapered stem was maintained. Especially, BMD in Gruen zone 1 which was maintained at 96% in comparison with the straight tapered stem. We compared the BMD change with clinical factors. There is no correlation between BMD and BMI, age or HHS. However, we found significant correlation between BMD and UCLA activity rating score in Gruen zones 1 and 2 of the triple tapered stem. Further, the correlation coefficient was increased at 48 months in comparison with 24 months.

Conclusion

The cementless triple tapered stem maintains periprosthetic bone mineral density. Activity may reflect improving periprosthetic bone quality after THA using a triple tapered stem.

Electronic supplementary material

The online version of this article (doi:10.1007/s00264-011-1407-3) contains supplementary material, which is available to authorized users.     

Restoration of proximal periprosthetic bone loss by denosumab in cementless total hip arthroplasty

Summary

Denosumab contributed to the restoration of proximal periprosthetic bone loss around the femoral stem that were measured using a DEXA, especially in zone 7, at 1 year after cementless THA in elderly osteoporotic patients.

Introduction

Although bone quality is an important issue in elderly osteoporotic patients who underwent total hip arthroplasty (THA) with a cementless stem, periprosthetic bone mineral density (BMD) in the proximal femur has been reported to be decreased by 15–40% postoperatively. Some authors have examined the use of several types of bisphosphonates to prevent decreases in BMD in the proximal femur after cementless THA; however, few reports have demonstrated success in restoring BMD in the proximal medial femoral bone, such as zone 7.

Methods

We conducted prospective study comparing patients who underwent cementless THA administered with denosumab (10 patients) and without denosumab (10 patients). BMD around the femoral stem were measured using a DEXA immediately after surgery, and at 6 months and at 1 year after surgery. No difference was found between the two groups referred to the patient’s demographic data.

Results

We found that denosumab displayed definitive effects in increasing the % change in periprosthetic BMD at zone 7 by an average of 7.3% in patients with cementless THA, compared to control group who were given only vitamin D.

Conclusion

Denosumab is one of a number of anti-osteoporotic agents to have a definitive effect on the restoration of proximal periprosthetic bone loss, especially in zone 7, after cementless THA. Denosumab contributed to the restoration of decreased periprosthetic BMD to normal levels. As the decrease in BMD in the proximal femur after THA is considered to be apparent at 6–12 months after surgery, it is believed that prevention of the deterioration of bone quality is important in the proximal femur immediately after cementless THA for elderly female patients with osteoporosis.

     

Risedronate reduces postoperative bone resorption after cementless total hip arthroplasty

Summary Forty-three patients who had undergone cementless THA were randomly assigned to receive no osteoactive drug or oral risedronate for 6 months. Postoperative decrease of BMD in the risedronate group was significantly lower than that seen in the control group in zones 1, 2, 3, 6, and 7. Introduction Proximal bone resorption around the femoral stem often has been observed after total hip arthroplasty (THA), could lead to late stem loosening. We previously reported the efficacy of etidronate on periprosthetic bone resorption after cementless THA. Recently risedronate is suggested to be effective for the prevention and treatment of for osteoporosis. The purpose of the present study was to evaluate the effects of risedronate on periprosthetic bone loss after cementless THA. Methods Forty-three patients who had undergone cementless THA were randomly assigned to receive no osteoactive drug (21 patients) or oral risedronate 2.5 mg/day (22 patients) for 6 months. Three patients were eliminated from the risedronate group because of dyspepsia. Periprosthetic bone mineral density (BMD) in seven regions of interest based on the zones of Gruen et al. was measured with dual energy X-ray absorptiometry at 3 weeks and 6 months postoperatively. Results At 6 months after surgery, postoperative decrease of BMD in the risedronate group was significantly lower than that seen in the control group in zones 1, 2, 3, 6, and 7 (p < 0.05, p < 0.01, p < 0.01, p < 0.05, and p < 0.05, respectively). Conclusion These outcomes suggested that risedronate might reduce the periprosthetic bone resorption after cementless THA.     

Changes in Bone Mineral Density of the Acetabulum and Proximal Femur After Total Hip Resurfacing Arthroplasty

Our aim was to investigate the changes in bone mineral density (BMD) of acetabulum and proximal femur after total hip resurfacing arthroplasty. A comparative study was carried out on 51 hips in 48 patients. Group A consisted of 25 patients (26 hips) who had undergone total hip resurfacing and group B consisted of 23 patients (25 hips) who had had large-diameter metal-on-metal total hip arthroplasty (THA). BMDs around the acetabulum and proximal femur were measured using dual-energy x-ray absorptiometry (DEXA) at 2 weeks, 6 months, 1 year and annually thereafter during the 3 years after surgery. At final follow-up, the acetabular net mean BMD decreased by 11% in group A and 10% in group B with no differences between two groups (P = .35). For the femoral side, in Gruen zone 1, the mean BMD increased by 4% in group A, whereas it decreased by 11% in group B (P = .029). In Gruen zone 7, the mean BMD increased by 8% at the final follow-up in group A, whereas it decreased by 13% in group B (P = .02). In both groups the mean BMD increased by 3% in Gruen zones 3, 4, 5, and 6. Stress-related bone loss of the acetabulum was comparable for MOM THA and resurfacing devices, but proximal femoral bone density increased in the resurfacing group and decreased in the THA group.     

Larger femoral periprosthetic bone mineral density decrease following total hip arthroplasty for femoral neck fracture than for osteoarthritis: A prospective,observational cohort study

Studies on patients with degenerative joint disease of the hip show that femoral periprosthetic bone mineral decreases following total hip arthroplasty. Scarcely any osteodensitometric data exist on femoral neck fracture (FNF) patients and periprosthetic bone remodelling. In two parallel cohorts we enrolled 87 patients (mean age, 72 ± 12 years; male:female ratio, 30:57) undergoing total hip arthroplasty for either primary osteoarthritis (OA) of the hip (n = 37) or for an acute FNF (n = 50) and followed them for a mean of 5.4 years. Outcomes were bone mineral density (BMD) changes in the periprosthetic Gruen zones 1–7, the incidence of periprosthetic fractures and clinical outcome. The bone mineral loss in the fracture group was more than twice that of the osteoarthritis group, ?16.9% versus ?6.8% (p = 0.004). The incidence of periprosthetic fractures was 12% (6/50) in the fracture cohort compared with none (0%) in the OA cohort (p = 0.03). Periprosthetic bone mineral loss following total hip arthroplasty is significantly greater in patients who are treated for acute FNF than in OA patients. This decrease of BMD follows a different pattern with the FNF patients losing larger proportions of bone in Gruen zones 1, 2, 6, and 7 while the OA patients tend to have larger losses only in zones 1 and 7. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:504–512, 2015.

     

Dual X-ray absorptiometry for the evaluation of bone density from the proximal femur after total hip arthroplasty: Analysis protocols and reproducibility

Summary Dual X-ray absorptiometry (DXA) instruments are now able to evaluate bone mineral density (BMD) of bone surrounding metal implants. The assessment of BMD around prosthetic components could provide additional information for the follow-up of total hip arthroplasty (THA). In this study, we evaluated the potential application of DXA in the field of THA. BMD was measured in the proximal femur of both THA and THA-free sides in 14 postmenopausal women 6–18 months after THA. The explored segment was divided into seven zones as proposed by Gruen et al. [18]. The precision error of BMD measurements ranged from 1.8 to 6.8% on the THA side and from 1.1 to 2% to the THA-free side. The reduction of BMD of the THA versus the THA-free side was significant in all seven zones (P < 0.01, t-test for paired data). These results showed significant differences in BMD around femoral components of THA with respect to contralateral healthy side, and demonstrate the sensitivity of DXA for detecting these changes.     

Pattern of Periprosthetic Bone Remodeling Around Stable Uncemented Tapered Hip Stems: A prospective 84-month follow-up study and a Median 156-month Cross-Sectional Study with DXA

Bone resorption in the proximal femur is commonly seen after total hip arthroplasty (THA). With dual energy X-ray absorptiometry (DXA), the amount of bone mass (BMD) after implantation of a total hip stem can be precisely determined. However, prospective evaluation of the change of bone mass around the stem is only available for selected stems and short-term follow-up (up to 36 months). We analyzed BMD in patients who had undergone uncemented THA by DXA. Only patients with good clinical outcome (Merle d Aubigné score > 12) were included to obtain normative data for regular bone response. Two separate studies were performed: a prospective longitudinal study over 84 months with baseline values acquired within the first postoperative week (group A) (n = 26 patients) and a separate cross-sectional study, median follow-up 156 (124-178) months (group B) (n = 35 patients). Regions of interest were defined according to Gruen (ROI 1-7) and as net average ROI (net avg) for the periprosthetic femoral bone. After the initial remodeling process (12 months), BMD was compared to the 84-month (longitudinal) and the 156-month (cross-sectional) follow-up values to determine long-term periprosthetic changes of bone mineral density. The longitudinal study (group A), after the initial bone remodeling, showed no relevant further bone loss for women and men with BMD values 1.19 ± 0.15 and 1.40 ± 0.19, respectively, 12 months (women 89.8%, men 93.6%), and 1.19 ± 0.13 and 1.36 ± 0.18, respectively, after 84 months (women 90.0%, men 91.3%) (P = 0.98, P = 0.08,) respectively. The distribution of the BMD around the stem changed during the first 12 months. The ROIs around the proximal stem (ROI 1 and 7) showed the lowest absolute values at the 12-month follow-up and BMD in ROI 7 decreased most during the further follow-up until 84 months. The cross-sectional study (group B) showed no significant difference in BMD (net avg) values at a median of 156 months follow-up compared to the 12-month values (group A) (women: P = 0.77, men: P = 0.44). Initial BMD, implant diameter, and body mass index did not influence BMD loss (net avg) in this study, whereas age showed a weak correlation with BMD loss. The results show that after the initial remodeling process, no relevant further bone loss (net avg) occurs up to 84 months postsurgery, and values after a median of 156 months are similar. Normative long-term changes in the periprosthetic bone can be demonstrated in defined ROIs after implantation of a tapered corundum-blasted titanium stem with a good clinical result.     

股骨假体周围骨密度定量测定

目的 通过双能X线骨密度仪测定不同情况下股骨假体周围的骨密度变化情况,了解骨丢失与股骨假体松动的关系。方法 分为骨水泥固定的股骨假体组、非骨水泥固定的股骨假体组、股骨假体松动组共3个组,采用LUNAR DPXL-L型双能X线骨密度仅(Lunar Corp Wisconsin,USA)及Orthopaedies软件,分析时用Gruen’s 7区法。结果 骨水泥固定的股骨假体组骨丢失为15．1%～29．3%,非骨水泥固定的股骨假体组骨丢失为13．2％～27．9%,股骨假体松动组骨丢失为25．4％～43．4%,3组均是股骨近端骨丢失明显．骨丢失主要发生在术后8年以内。结论 骨水泥固定的股骨假体和非骨水泥固定的股骨假体周周骨密度降低一样,假体松动者假体周围骨丢失明显增加。股骨近端2个以上区域骨丢失大于35％或术后8年以后突然出现明显的骨丢失,考虑有股骨假体松动存在的可能性。     

Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty: A randomized clinical trial with DXA and RSA in 51 patients

Background and purpose — We hypothesized that an ultra-short stem would load the proximal femur in a more physiological way and could therefore reduce the adaptive periprosthetic bone loss known as stress shielding.Patients and methods — 51 patients with primary hip osteoarthritis were randomized to total hip arthroplasty (THA) with either an ultra-short stem or a conventional tapered stem. The primary endpoint was change in periprosthetic bone mineral density (BMD), measured with dual-energy x-ray absorptiometry (DXA), in Gruen zones 1 and 7, two years after surgery. Secondary endpoints were change in periprosthetic BMD in the entire periprosthetic region, i.e. Gruen zones 1 through 7, stem migration measured with radiostereometric analysis (RSA), and function measured with self-administered functional scores.Results — The periprosthetic decrease in BMD was statistically significantly lower with the ultra-short stem. In Gruen zone 1, the mean difference was 18% (95% CI: −27% to −10%). In zone 7, the difference was 5% (CI: −12% to −3%) and for Gruen zones 1–7 the difference was also 5% (CI: −9% to −2%). During the first 6 weeks postoperatively, the ultra-short stems migrated 0.77 mm more on average than the conventional stems. 3 months after surgery, no further migration was seen. The functional scores improved during the study and were similar in the 2 groups.Interpretation — Up to 2 years after total hip arthroplasty, compared to the conventional tapered stem the ultra-short uncemented anatomical stem induced lower periprosthetic bone loss and had equally excellent stem fixation and clinical outcome.Periprosthetic bone loss in uncemented femoral stems can contribute to late-occurring periprosthetic fractures (Lindahl 2007, Streit et al. 2011). This is partly mediated by adaptive bone resorption. This disuse atrophy, known as stress shielding, is mainly a consequence of the mismatch in modulus of elasticity between the implant and the periprosthetic bone. In time, the increasingly more fragile periprosthetic bone may break—even after minor trauma. Shorter femoral stems, aimed at giving a more physiological load pattern in the proximal femur, have become popular lately because of expectations of reducing stress shielding. Absence of a diaphyseal engaging stem is a key factor to prevent off-loading of the proximal femoral bone, but at the same time it will challenge the primary stability necessary for bone osseointegration of the femoral implant (Søballe et al. 1992).In this study, we hypothesized that an ultra-short uncemented stem would give less periprosthetic bone loss in the proximal femur than a conventional tapered uncemented stem, and that the ultra-short stem would achieve good fixation and be safe to use from a clinical standpoint.     

全髋关节表面置换术后股骨近端骨密度的变化

目的评价全髋关节表面置换术对股骨近端骨量变化的影响。方法2002年7月至2005年6月,对行全髋关节表面置换术（表面置换组）和人工全髋关节置换术（全髋置换组）各26例患者作为研究对象,均在术前、术后3、6、12和24个月时对股骨近端按Gruen分区设为7个测量感兴趣区,表面置换组加股骨颈外上和内下区,应用双能X线吸收测定仪测定骨密度,比较两组术前和术后股骨近端骨密度变化。结果术后3、6、12和24个月时,表面置换组股骨近端骨密度分别降低5．8％、4．9％、2．6％和0．4％;测量感兴趣区1的骨密度术后6个月时降至89．7％,至24个月时增至103．8％;测量感兴趣区7的骨密度术后6个月时降至95．1％,24个月时增至103．7％;股骨颈部骨密度在术后6个月时即可恢复至术前水平,股骨颈外上区的骨密度术后3个月时降至97．1％,术后24个月时增至107．4％（P〈0．05）;股骨颈内下区的骨密度术后24个月时增至117．9％（P〈0．05）。全髋置换组股骨近端骨密度分别降低7．0％、10．6％、1．0％和4．1％。测量感兴趣区1的骨密度术后6个月降至90．8％,术后24个月时为94．4％;测量感兴趣区7术后3个月降至94．2％,术后24个月时为96．7％。结论全髋关节表面置换术后股骨近端骨量可以得到有效保存和恢复。