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

Femoral stem taper geometry and porous coating in cementless direct anterior primary total hip arthroplasty

Objective

This study aims to compare the clinical outcomes and complications between a fully coated, dual-tapered hip stem versus a proximally coated, triple-tapered hip stem in patients undergoing cementless direct anterior (DA) primary total hip arthroplasty (THA).

Methods

A retrospective analysis was conducted on patients who underwent primary THA with either a fully coated, dual-tapered hip stem or a proximally coated, triple-tapered stem with at least a 1-year follow up. Exclusion criteria included any patients that did not receive either femoral stem, those undergoing bilateral THA, those with a surgical approach other than DA, those with an indication other than osteoarthritis, avascular necrosis (AVN), or femoral neck fracture, and those that had a cemented femoral component. Complications and clinical outcomes were assessed. Statistical analyses were conducted to identify significant differences between the groups.

Results

A total of 95 patients were included in the study. The average ages for the dual-tapered and triple-tapered stem cohorts were 63.6 and 59.5, respectively (p = 0.168). At 1-year follow-up, no significant differences were seen between the groups in terms of ambulatory status, ROM, and patient satisfaction (p = 0.414, p = 0.106, and p = 0.126). 6 (18 %) of the patients receiving the dual-tapered, fully coated hip stem had at least one complication while 8 (13 %) of the triple-tapered, proximally coated hip stem patients did (p = 0.550).

Conclusion

Both hip stem cohorts demonstrated comparable clinical outcomes and complication rates in patients undergoing primary DA THA and we believe that either hip stem may be a reasonable choice for patients. Future studies with larger sample sizes and longer follow-up periods are warranted to validate these findings.

Design and manufacturing of patient-specific Ti6Al4V implants with inhomogeneous porosity

Stress shielding remains a challenge in orthopaedic implants, including total hip arthroplasty. Recent development in printable porous implants offers improved patient-specific solutions by providing adequate stability and reducing stress shielding possibilities. This work presents an approach for designing patient-specific implants with inhomogeneous porosity. A novel group of orthotropic auxetic structures is introduced, and their mechanical properties are computed. These auxetic structure units were distributed at different locations on the implant along with optimized pore distribution to achieve optimum performance. A computer tomography (CT) based finite element (FE) model was used to evaluate the performance of the proposed implant. The optimized implant and the auxetic structures were manufactured using laser powder bed-based laser metal additive manufacturing. Validation was done by comparing FE results with experimentally measured directional stiffness and Poisson's ratio of the auxetic structures and strain on the optimized implant. The correlation coefficient for the strain values was within a range of 0.9633-0.9844. Stress shielding was mainly observed in Gruen zones 1, 2, 6, and 7. The average stress shielding on the solid implant model was 56%, reduced to 18% when the optimized implant was used. This significant reduction in stress shielding can decrease the risk of implant loosening and create an osseointegration-friendly mechanical environment on the surrounding bone. The proposed approach can be effectively applied to the design of other orthopaedic implants to minimize stress shielding.

Fully hydroxyapatite-coated compaction broached and triple-tapered stem may reduce the risk of stress shielding after primary total hip arthroplasty

PURPOSE

Changes in bone mineral density (BMD) around the fully hydroxyapatite (HA)-coated compaction broached and triple-tapered stem, namely, Polarstem, after total hip arthroplasty (THA) are currently unknown. Therefore, the aims of this study were to investigate clinical outcomes of Polarstem, mainly postoperative temporal changes in BMD around the stem for 2 years, and to compare them with those of HA-coated and non-HA-coated tapered-wedge stems.

METHODS

This retrospective cohort study enrolled 100 consecutive patients who underwent THA using Polarstem (n = 38), HA-coated Anthology (n = 31), and non-HA-coated Anthology (n = 31). BMD was evaluated using dual-energy X-ray absorptiometry in seven regions according to the Gruen zones. Postoperatively, BMD around the stem was assessed within 2 months (baseline BMD) and at 6, 12, and 24 months. A change in BMD was defined as the value calculated by dividing each postoperative BMD value at 6, 12, and 24 months by the baseline BMD value. Changes in BMD and radiographic parameters such as stress shielding and spot welds were compared among the three stems.

RESULTS

The incidence rate of stress shielding in the Polarstem group was significantly lower than those in the other two groups (p = 0.007). The change in BMD in Zone 7 of Polarstem was significantly more than that of the other two groups at 12 and 24 months postoperatively (p = 0.030 and p = 0.009, respectively).

CONCLUSION

Polarstem, a fully HA-coated compaction broached and triple-tapered stem, maintained BMD around the femoral calcar until 2 years postoperatively and could reduce the risk of stress shielding compared with tapered-wedge stems.

The influence of stem alignment on the bone mineral density around the Polarstem following total hip arthroplasty

INTRODUCTION

Bone mineral density is important in detecting implant loosening after total hip arthroplasty. The Polarstem can improve postoperative bone mineral density changes, but no information exists on the influence of postoperative stem alignment. Therefore, we investigated the relationship between bone mineral density change and stem alignment following total hip arthroplasty using a cementless Polarstem.

MATERIALS AND METHODS

This retrospective study included 42 patients (50 hips) who underwent total hip arthroplasty using a cementless Polarstem. Bone mineral density around the stem was measured according to the established Gruen zone classification using dual-energy X-ray absorptiometry. Measurements were performed 2 months postoperatively (baseline) and 6, 12, 18, and 24 months postoperatively. Bone mineral density changes at each follow-up were calculated as (bone mineral density at follow-up/at 2 weeks) × 100 (%). The stem varus, anterior tilt, and anteversion angles were measured using computed tomography. The correlation coefficient between bone mineral density changes and stem alignment were investigated.

RESULTS

The 24-month postoperative bone mineral density increased in zones 4 (106.0%) and 5 (107.3%) and decreased in zones 1 (89.6%) and 7 (90.6%). The mean stem varus angle, anterior tilt, and anteversion error were - 0.3° ± 1.8°, 1.9° ± 2.2°, and 6.8° ± 5.4°. Negative correlations were observed between the stem varus angle and 24-month postoperative bone mineral density change in zone 1 (r = - 0.34, p = 0.02), and the stem anteversion error and 24-month postoperative bone mineral density change in zone 1 (r = - 0.48, p < 0.01) and zone 7 (r = - 0.31, p = 0.03).

CONCLUSIONS

The cementless Polarstem may have a positive effect on postoperative bone mineral density in the distal femur. However, varus malalignment and anteversion error of the stem could have a negative influence on the bone mineral density changes in the proximal femur.

Effect of implant composition on periprosthetic bone mineral density after total hip arthroplasty

BACKGROUND

The severity of bone mineral density (BMD) loss after total hip arthroplasty (THA) depends on both implant- and patient-related factors. While implant fixation type is an important factor, but few studies have considered the effect of material composition on the same implant fixation type. In particular, differences in mechanical stiffness due to material composition are of great interest. Here, we compared changes in periprosthetic BMD after THA using proximal fixation concept stems comprising different titanium alloys, i.e., β titanium alloys stem and α + β titanium alloys stem.

METHODS

This retrospective cohort included 122 patients (β titanium alloys stem, 61 cases; α + β titanium alloys stem, 61 cases) who underwent primary THA between January 2009 and December 2019. The primary outcome was the change in periprosthetic BMD from base line. Age, body mass index, diagnosis, stem size, canal flare index, surgical approach, pre-operative lumbar BMD, and pre-operative activity scores were reviewed and changes in periprosthetic BMD between the two groups were compared using analysis of covariance. The secondary outcome was radiographic response after THA.

RESULTS

There was significant difference in periprosthetic BMD in zone 6 and 7 at 2 years (p < 0.05) between the two groups. There was no significant difference in other zones. A significant difference in radiographic response was noted only for the Engh classification.

CONCLUSION

α + β titanium alloys stem resulted in a significantly higher rate of BMD loss in zones 6 and 7 compared with the β titanium alloys stem. These results may be due to differences in mechanical stiffness due to the different titanium alloy composition of the prosthetics.

Effects of porous tantalum on periprosthetic bone remodeling around metaphyseal filling femoral stem: a multicenter, prospective, randomized controlled study

Periprosthetic bone loss due to adaptive bone remodeling is an important unresolved issue in cementless total hip arthroplasty (THA). The use of porous tantalum on the proximal surface of the femoral stem is expected to decrease postoperative bone loss around the prosthesis through early fixation. We conducted a multicenter randomized controlled study to determine if porous tantalum could reduce periprosthetic bone loss after THA. From October 2012 to September 2014, 118 patients (mean age, 61.5 years; 107 females and 11 males) were prospectively enrolled and were randomly allocated at a ratio of 1:1 to either a metaphyseal filling stem with a proximal porous tantalum coating (Trabecular Metal) or a conventional metaphyseal filling stem with fiber mesh coating (VerSys). Patients underwent dual-energy x-ray absorptiometry scans within 1 week after surgery (baseline) and at 6, 12, and 24 months after surgery to assess periprosthetic bone mineral density (BMD) in the 7 Gruen zones. In addition, the Japanese Orthopaedic Association hip score was assessed before surgery and at 6, 12, and 24 months after surgery. In the proximal periprosthetic region (zones 1 and 7), the Trabecular Metal group had significantly smaller reductions in BMD than the VerSys group throughout the study period. In the VerSys group, significant reductions in BMD compared to baseline were seen at each measurement point in all regions, except in zone 6 at 24 months. In the Trabecular Metal group, no significant reductions in BMD relative to baseline were seen in zones 1, 5, or 6 throughout the study period. Both groups demonstrated similar improvement in Japanese Orthopaedic Association hip scores over the study period. This study demonstrated that a proximally coated stem with porous tantalum has superior results over a conventional stem with titanium fiber mesh in terms of periprosthetic bone remodeling.

Amount and type of physical activity and sports from one year forward after hip or knee arthroplasty-A systematic review

INTRODUCTION

After rehabilitation following total hip or knee arthroplasty (THA/TKA), patients are advised to participate in physical activity (PA) and sports. However, profound insight into whether people adopt a physically active lifestyle is lacking. Aim is to gain insight into the performed amount and type of PA (including sports) and time spent sedentarily by persons after THA/TKA.

METHODS

A systematic review (PROSPERO: CRD42020178556). Pubmed, Cinahl, EMBASE and PsycInfo were systematically searched for articles reporting on amount of PA, and on the kind of activities performed between January 1995-January 2021. Quality of the articles was assessed with the adapted tool from Borghouts et al.

RESULTS

The search retrieved 5029 articles, leading to inclusion of 125 articles reporting data of 123 groups; 53 articles reported on subjects post-THA, 16 on post-hip-resurfacing arthroplasty, 40 on post-TKA, 15 on post-unicompartimental knee arthroplasty and 12 on a mix of arthroplasty types. With respect to quality assessment, 14 articles (11%) met three or fewer criteria, 29 (24%) met four, 32 (26%) met five, 42 (34%) met six, and 6 (5%) met seven out of the eight criteria. PA levels were comparable for THA and TKA, showing a low to moderately active population. Time spent was mostly of low intensity. Roughly 50% of -subjects met health-enhancing PA guidelines. They spent the largest part of their day sedentarily. Sports participation was relatively high (rates above 70%). Most participation was in low-impact sports at a recreational level. Roughly speaking, participants were engaged in sports 3 hours/week, consisting of about three 1-hour sessions.

CONCLUSION

Activity levels seem to be low; less than half of them seemed to perform the advised amount of PA following health-enhancing guidelines Sports participation levels were high. However, many articles were unclear about the definition of sports participation, which could have led to overestimation.

Factors Affecting Periprosthetic Bone Loss after Hip Arthroplasty

Periprosthetic bone loss may lead to major complications in hip arthroplasty, including aseptic loosening, implant migration, and even periprosthetic fracture. Such a complication leads to revision surgeries, which are expensive, technically demanding, and result in a low satisfaction rate. Therefore, a study was conducted of the factors affecting the periprosthetic bone loss around the stem that caused these complications. Factors influencing periprosthetic bone loss include demographic factors such as age, sex, obesity, smoking, and comorbidity including diabetes and osteoporosis. The implant design and fixation method are also factors that are determined before surgery. In addition, there are surgical factors, such as surgical approach and surgical technique, and we wish to investigate the factors affecting periprosthetic bone loss around the stem by comparing the effects of postoperative rehabilitation protocols and osteoporosis drugs.

Preoperative factors predicting the severity of BMD loss around the implant after Total hip Arthroplasty

Background

Stress shielding after total hip arthroplasty (THA) leads to loss of bone mineral density (BMD) around the femoral implants, particularly in the proximal area. Loss of BMD around the implant is likely to occur within 1 year after THA; however, its severity depends on patient characteristics. This study evaluated preoperative factors correlated with the severity of zone 7 BMD loss after THA.

Methods

This retrospective cohort study included 48 patients who underwent primary THA from October 2011 to December 2015. All patients underwent implantation of a Zweymüller-type femoral component without any postoperative osteoporosis medications. The objective variable was a change in zone 7 BMD after 1 year. Factors evaluated included age, body mass index, Japanese Orthopaedic Association score, Harris Hip Score, Canal Flare Index (CFI), and lumbar BMD on the frontal and lateral sides. Univariate and multivariate regression analyses identified factors correlated with loss of zone 7 BMD.

Results

Univariate regression analysis identified CFI (P = 0.003) and preoperative lumbar BMD on the anterior-posterior (P = 0.003) and lateral (P < 0.001) sides as being correlated with loss of zone 7 BMD. Multivariate regression analysis identified CFI (P = 0.014) and lumbar BMD on the lateral side (P < 0.001) as being correlated independently with loss of zone 7 BMD.

Conclusion

Lower preoperative lumbar BMD on the lateral side and lower CFI were correlated with zone 7 BMD loss after THA. Patients with these characteristics should be monitored carefully for severe BMD loss after THA.

Bone Loss Following Cementless Hemiarthroplasty for the Treatment of Femoral Neck Fracture

BACKGROUND

With the advances in medicine, an increasing number of the ageing population are a public health concern in terms of age-related complications. Among them, displaced neck fractures often require surgical intervention or arthroplasty to achieve the mobilization of the elderly and good life quality. The aim of the study is to monitor the changes in bone mineral density (BMD) around the femoral stem and the effects on functional outcomes in patients treated with cementless hemiarthroplasty following femoral neck fracture.

MATERIALS AND METHODS

Seventy-one patients aged 70 years or older who were treated with cementless hemiarthroplasty for a displaced femoral neck fracture were prospectively followed for 2 years. The percent change in the periprosthetic BMD in each Gruen zone was compared to the baseline using dual-energy X-ray absorptiometry (DEXA). Demographic factors [age, body mass index (BMI), and sex] that could possibly influence BMD and the clinical outcome were evaluated.

RESULTS

Fifty-one patients were available for the final follow-up. The mean age was 76.5 (range 70-89) years. The mean BMI was 28.9 (range 22.7-37.2). The mean Harris hip score at the final follow-up was 84.3 (range 72-93). There was a significant decrease in BMD in all Gruen zones (p < 0.001), except in zone 3 (R3, p = 0.547). The reduction in BMD was highest in the calcar and the greater trochanter region. The femur diaphysis was relatively spared, with zone 3 showing no significant bone mineral loss. The age and BMI of the patients were not correlated with the postoperative change in BMD in any of the Gruen zones. The degree of reduction in bone density was not correlated with the clinical outcome.

CONCLUSIONS

Cementless hemiarthroplasty for the treatment of femoral neck fracture in elderly patients achieves a good clinical outcome despite significant bone loss around the femoral stem. The reduction in BMD is more pronounced in the metaphyseal region.

Long-term outcomes of a dual-mobility cup and cementless triple-taper femoral stem combination in total hip replacement: a multicenter retrospective analysis

BACKGROUND

The separate design concepts of dual-mobility cups and triple-taper femoral stems were developed to improve survivorship following total hip replacement (THR) by reducing instability/dislocation and enabling enhanced fixation. Successful outcomes at over two decades have been reported with earlier-generation devices based on these concepts. The current study aimed to provide the first long-term results with a unique pairing of later-generation dual-mobility cup and triple-taper cementless femoral stem after a decade of use in patients undergoing THR.

METHODS

In this retrospective analysis, records were reviewed for all subjects implanted with this dual-mobility cup/cementless femoral stem combination at three centers between 2002 and 2005. Any subject who had not already had follow-up visit beyond 10 years, was not previously revised, and still living were invited for a single follow-up visit consisting of Merle d'Aubgine Scores, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, and standard radiographs.

RESULTS

There were 244 THRs available for analysis. At a mean follow-up of 11.9 years, the Kaplan-Meier survivorship (endpoint: revision for any reason) was 99.1% (95% CI, 97.6-99.7) for the stem and 95.9% (95% CI, 93.1-97.6) for the cup. Merle d'Aubigne Scores were significantly improved from baseline and WOMAC scores were in the satisfactory range at the final follow-up. Radiographic analysis revealed no cases of stem subsidence, no cases of bone hypertrophy, 1 (0.4%) case of bone atrophy, and 3 (1.2%) cases of osteolysis around the stem. No subjects had radiolucent lines greater than 1 mm in any femoral Gruen zone. Evidence of cup migration was seen in 1 (0.4%) subject and 1 (0.4%) subject had evidence of osteolysis that was seen in Gruen zones I, II, IV, and V.

CONCLUSIONS

This combination of a later-generation dual-mobility cup and cementless triple-taper stem was associated with excellent survivorship and satisfactory functional outcomes at over 10 years follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02648152. Date of registration: January 6, 2016. Retrospectively registered.

A calcar collar is protective against early periprosthetic femoral fracture around cementless femoral components in primary total hip arthroplasty: a registry study with biomechanical validation

AIMS

The aim of this study was to estimate the 90-day risk of revision for periprosthetic femoral fracture associated with design features of cementless femoral stems, and to investigate the effect of a collar on this risk using a biomechanical in vitro model.

MATERIALS AND METHODS

A total of 337 647 primary total hip arthroplasties (THAs) from the United Kingdom National Joint Registry (NJR) were included in a multivariable survival and regression analysis to identify the adjusted hazard of revision for periprosthetic fracture following primary THA using a cementless stem. The effect of a collar in cementless THA on this risk was evaluated in an in vitro model using paired fresh frozen cadaveric femora.

RESULTS

The prevalence of early revision for periprosthetic fracture was 0.34% (1180/337 647) and 44.0% (520/1180) occurred within 90 days of surgery. Implant risk factors included: collarless stem, non-grit-blasted finish, and triple-tapered design. In the in vitro model, a medial calcar collar consistently improved the stability and resistance to fracture.

CONCLUSION

Analysis of features of stem design in registry data is a useful method of identifying implant characteristics that affect the risk of early periprosthetic fracture around a cementless femoral stem. A collar on the calcar reduced the risk of an early periprosthetic fracture and this was confirmed by biomechanical testing. This approach may be useful in the analysis of other uncommon modes of failure after THA. Cite this article: Bone Joint J 2019;101-B:779-786.

Short to Midterm Follow-Up of Periprosthetic Bone Mineral Density after Total Hip Arthroplasty with the Ribbed Anatomic Stem

Background

Femoral bone remodeling around hip prosthesis after total hip arthroplasty (THA) is definite but unpredictable in time and place. This study aimed to investigate the implant-specific remodeling and periprosthetic bone mineral density (BMD) changes after implantation of the Ribbed anatomic cementless femoral stem.

Methods

After power analysis, 41 patients who had undergone primary unilateral THA with the Ribbed anatomic cementless stem were included. BMD of the seven Gruen zones was measured by dual-energy X-ray absorptiometry, and the contact, fitness, and fixation of the femoral stem and proximal femur were analyzed by X-ray. Additional clinical outcome parameters were also recorded.

Results

Compared with the contralateral unoperated side, significant reductions of BMD were detected in the distal zone (Gruen zone 4: 1.665±0.198 versus 1.568±0.242 g/cm², P=0.001) and middle distal zone (Gruen zone 5: 1.660±0.209 versus 1.608±0.215 g/cm², P=0.026) on the prosthetic side, but no significant differences in BMD were detected in other zones (Gruen zones 1, 2, 3, 6, and 7). Subgroups analyses indicated no significant correlation between periprosthetic BMD changes and clinical factors including primary disease and body mass index. Visible areas of bone ingrowth indicated solid fixation of the femoral stem and there was no case of loosening. Clinical and functional outcome scores were excellent with mean HHS of 93.13 points and mean WOMAC score of 5.20 points, and three patients described intermittent mild thigh pain at the final follow-up.

Conclusions

For the Ribbed femoral stem, the periprosthetic BMD was well maintained in the proximal femur, while periprosthetic BMD was significantly reduced in the distal and middle distal zones of the femur. Further clinical investigations are required to examine the efficacy of the Ribbed stem, particularly with regard to long-term survival. This trial is registered with ChiCTR1800017750.

Less periprosthetic bone loss following the anterolateral approach to the hip compared with the direct lateral approach

Background and purpose - The loss of bone mineral in the proximal femur following hip arthroplasty may increase the fracture risk around uncemented stems. We hypothesized that the surgical approach to the hip might influence bone mineral changes around the femoral stem in patients with a femoral neck fracture (FNF). Patients and methods - This was a pre-specified subgroup analysis (n = 51) of an ongoing randomized trial (n = 120) in patients with FNF. Participants were allocated to an uncemented hemiarthroplasty inserted through a direct lateral (Hardinge) approach or an anterolateral (modified Watson-Jones) approach. The 51 patients (mean age 83 (70-90) years, 33 women) were measured by dual-energy X-ray absorptiometry (DXA) to assess changes in periprosthetic bone mineral density (BMD). Results - The mean change in total BMD differed between groups at 12 months in favor of the anterolateral group (4.8%, 95% CI 0.0-9.6; p = 0.05). DXA at 3 months displayed BMD loss in the proximal Gruen zones in the lateral group compared with the anterolateral group. Zone 1 (-5.0% vs. 2.7%), zone 2 (-4.3% vs. 4.1%), zone 6 (-6.5% vs. 0.0%) and zone 7 (-11% vs. -2.4%, all p < 0.05). Interpretation - DXA measurements in this study indicate that surgical approach to the hip influences periprosthetic BMD. Clinical implications remain uncertain. Our conclusions should be interpreted with caution as we did not perform adjustments for multiple tests, possibly leading to inflation of false-positive findings.

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design

INTRODUCTION

Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA.

METHODS

The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled. Using these results, we compared percent changes in bone loss as a function of: femoral stem fixation, material, and geometry.

RESULTS

The greatest bone loss was in the calcar region (Gruen Zone 7). Overall, cemented stems had more bone loss distally than noncemented stems, while noncemented stems had more proximal bone loss than cemented stems. Within noncemented stems, cobalt-chromium (CoCr) stems had nearly double the proximal bone loss compared to titanium (Ti) alloy stems. Finally, within noncemented titanium alloy group, straight stems had less bone loss than anatomical, tapered, and press-fit designs.

DISCUSSION

The findings from the present study quantified percent changes in periprosthetic BMD as a function of fixation method, alloy, and stem design. While no one stem type was identified as ideal, we now have a clearer understanding of the influence of stem design on load transfer to the surrounding bone.

Daily activity and initial bone mineral density are associated with periprosthetic bone mineral density after total hip arthroplasty

OBJECTIVES

To evaluate periprosthetic bone mineral density (BMD) changes around a cementless short tapered-wedge stem and determine correlations between BMD changes and various clinical factors, including daily activity, after total hip arthroplasty (THA) with a tapered-wedge stem.

METHODS

65 patients underwent THA with a TriLock BPS stem. At baseline and at 6, 12, and 24 months postoperatively the BMD of the 7 Gruen zones were evaluated using dual-energy x-ray absorptiometry. Correlations were determined between BMD changes and clinical factors, including the Harris Hip Score, body mass index, University of California at Los Angeles (UCLA) activity rating score, age at surgery, and initial spine BMD. Radiographic parameters, including the proximal femoral geometry (Dorr Classification), canal filling ratio, canal flare index, and calcar-to-canal ratio were also assessed.

RESULTS

Minimal BMD changes were noted in the distal femur. However, significant BMD loss was noted in zone 7 at each time point. BMD loss was also noted in zone 1 at 6 and 12 months postoperatively, but BMD recovered after 18 months. Significant positive correlations were noted between BMD changes and the UCLA activity score in zones 1, 6, and 7. Additionally, negative correlations were noted between BMD changes and the preoperative lumbar BMD in zones 2 and 3. No correlations were noted between BMD changes and the radiographic parameters. Periprosthetic BMD was was virtually unchanged in the proximal femur, especially Gruen zone 1.

CONCLUSIONS

Daily activity may reflect improvements in periprosthetic bone quality after THA; however, the use of this tapered-wedge stem is not recommended in patients with poor bone quality.

Stem anteversion affects periprosthetic bone mineral density after total hip arthroplasty

AIMS

The present study aimed to evaluate periprosthetic bone mineral density (BMD) changes around a cementless short tapered-wedge stem used for total hip arthroplasty (THA) and to determine the correlation between BMD changes and stem alignment after THA.

METHODS

The study included 21 patients (21 joints) who underwent THA with a TriLock stem. At baseline and 6, 12, 18, and 24 months postoperatively, the BMDs in the 7 Gruen zones were evaluated using dual-energy X-ray absorptiometry. BMD changes and stem alignment, that is, anteversion, varus, and anterior tilt, were correlated.

RESULTS

Minimal BMD changes were found in the distal femur (Gruen zones 3, 4, and 5), but significant BMD loss was noted in zone 7. BMD loss was also noted in zone 1 at 6 and 12 months postoperatively, but it recovered after 18 months. No correlation was found between BMD changes and anterior tilt. However, significant negative correlations were found between BMD changes and anteversion. Furthermore, significant negative correlations were found between BMD changes and varus in Gruen zone 1, while positive correlations were found between BMD changes and varus in Gruen zone 7.

CONCLUSIONS

We demonstrated that periprosthetic BMD was well maintained in the proximal femur after THA with a short tapered-wedge stem and that stem anteversion affects periprosthetic BMD after THA.

Teriparatide Versus Alendronate for the Preservation of Bone Mineral Density After Total Hip Arthroplasty - A randomized Controlled Trial

In this study, the effect of teriparatide for the prevention of bone mineral density (BMD) loss after THA was compared with alendronate in a randomized controlled trial. Forty-eight patients were assigned to three groups, namely, the teriparatide, alendronate, and no medication groups. Dual-energy x-ray absorptiometry (DEXA) was performed at 1 week post-surgery as a baseline reference, followed by subsequent measurements at 12, 24, and 48 weeks postoperatively. For periprosthetic BMD loss, a significant effect of teriparatide was demonstrated, though its effect was similar to alendronate. On the other hand, higher lumbar BMD was observed in the teriparatide group than in the alendronate group at 48 weeks post-surgery. Teriparatide administration may be one reasonable option for osteoporotic patient to preserve the periprosthetic BMD after THA.

Stro-1-positive BMSCs predict postoperative periprosthetic bone mineral density outcomes in uncemented total hip arthroplasty patients

Background

Bone marrow cell profiles are variable after total hip arthroplasty (THA), including variable levels of Stro-1⁺ and bone morphogenetic protein receptor (BMPRs)⁺ cells. We investigated the impact of bone marrow cell profiles on changes in periprosthetic bone mineral density (BMD) in uncemented THA patients.

Material/Methods

Bone marrow aspirates were collected from the metaphyseal region of discarded femoral heads from 24 consecutive THA patients (12 men and 12 women; mean age 66.7±11.0 years; range 52–87 years) treated from March 2009 to March 2011 at a single facility. Perioperative proportions of Stro-1⁺ and BMPR⁺ cells in femoral heads were assessed by flow cytometry. Follow-up examined the proximal femur Gruen zones R1 and R7 at 1 week and at 3, 6, and 12 months after THA, using dual-energy X-ray absorptiometry. Associations between BMD loss and age, gender, BMPRs⁺, and Stro-1⁺ were analyzed.

Results

At 3 months, R1 and R7 BMD decreased by 4.4% and 6.4%, respectively (P<0.05). At 12 months, the overall BMD decreases in R1 and R7 were 10.2% and 1%, respectively (P<0.05). Higher Stro-1⁺ cells proportion predicted R7 BMD increases at all time points (P<0.05) and R1 BMD increases at 6 and 12 months (P<0.05). BMPR1a⁺ proportion was associated with BMD increases at 6 months in the R1 region. BMPR2⁺ was not significantly associated with BMD (P>0.05).

Conclusions

Elevated Stro-1⁺ bone marrow cell profile may be a useful prognostic indicator for uncemented THA patients.

Influence of surgical approach on postoperative femoral bone remodelling after cementless total hip arthroplasty

We retrospectively evaluated the femoral periprosthetic bone mineral density (BMD) in a consecutive series of patients who had undergone total hip arthroplasty (THA) with a straight, double tapered cementless stem using a muscle-sparing anterolateral (group A) and the transgluteal (group B) surgical approach. Dual-energy x-ray absorptiometry (DXA) measurements were performed in the first postoperative week (t1), and after 3 (t2), 6 (t3) and 12 months (t4) using an identical protocol. Patients were clinically and radiographically evaluated at final follow-up (t4). A complete set of four consecutive DXA measurements was obtained for 16 hips in group A and 26 hips in group B. In patients in whom the transgluteal approach was used (Group B), we observed a significantly greater decline in overall periprosthetic BMD (netavg) and in BMD in the periprosthetic regions of interest (ROI) 1, 4, 5 and 6 between t1 and t4. At clinical and radiographic evaluation at t4, no differences between the groups were detected. Femoral periprosthetic BMD is affected by the selected surgical approach in the first postoperative year. This might be attributed to altered femoral loading as a result of differences in intraoperative damage to the abductor muscles.