Periprosthetic bone remodeling around short stem

Results of Total Hip Replacement Surgery Using Short-Stem Spiron Prosthesis in Vietnamese Adults

Introduction

Total hip arthroplasty with traditional stem joints, although bringing many benefits to patients indicated for hip replacement, faces many difficulties in reoperations in young patients due to the limited lifespan of the artificial joint. Recently, the short-stem joint was introduced to help overcome this problem. This study aims to evaluate the results of short-stem implants for primary total hip arthroplasty in Vietnamese adults.

Materials and Methods

The study design is retrospective longitudinal. The study subjects were 91 patients with aseptic necrosis of the femoral head who underwent short-shaft cementless total hip replacement surgery from February 2012 to December 2018. Outcomes that were assessed included implant survivorship, Harris hip scores, thigh pain, periprosthetic fracture, subsidence, proximal stress shielding, the prevalence of stem malalignment, and inappropriate implant sizing.

Results

Our research group has 119 hips of 91 patients (28 patients had hip replacements on both sides), with the average follow-up time of 67.1 months. Seven cases of early joint loosening required replacing the traditional stem. The survival rate is 94.1%. The average Harris hip score 24 months after surgery was statistically significantly higher than before (92.00 ± 4.47 and 45.56 ± 3.22, respectively, p < 0.001). The average leg length discrepancy between the two limbs before surgery was 9.5 ±mm and 24 months after surgery was 3.4 ± 2.9 mm. There were 12 cases (10.1%) of partial bone loss around the femoral stem; 12 cases of joint displacement of more than 2 mm, accounting for 10.1%; and 1 case of acetabular fracture, accounting for 0.8%.

Conclusion

The Spiron short stem has certain advantages suitable for young patients, restoring the hip anatomy and significantly improving postoperative hip function. However, this is a complex technique that needs to be performed by experienced surgeons who have practiced for a long time. We encourage using the short-stem implant during primary total hip arthroplasty in Vietnamese adult patients.

Stable fixation of an ultra-short femoral neck-preserving hip prosthesis: a 5-year RSA, DXA, and clinical prospective outcome study of 48 patients

BACKGROUND AND PURPOSE

We previously showed promising primary stability and preservation of bone stock with the ultra-short neck-loading hip implant in total hip arthroplasty (THA). The aim of this study was to evaluate clinical outcome, implant stability, and bone mineral density (BMD).

METHODS

50 patients were treated with the ultra-short neck Primoris hip implant at baseline and 48 were available for evaluation at 5-year follow-up. 5 different patient-reported outcome measures (PROMs) including hip-specific scores, disease-specific and generic quality of life outcome measures, and an activity score were used. Furthermore, implant stability using radiostereometric analysis (RSA) and assessment of periprosthetic BMD using dual-energy X-ray absorptiometry (DXA) were applied.

RESULTS

By 1-year follow-up, all PROMs showed improvements and remained high at 5-year follow-up. After initial distal translation (subsidence) and negative rotation around the z-axis (varus tilt) the implant showed stable fixation at 5-year follow-up with no further migration beyond 12 months. In the regions of interest (ROI) 3 and 4, BMD remained stable. In ROI 2, further bone loss of 12% was found at 5-year follow-up.

CONCLUSION

Clinical outcome including PROMs was satisfying throughout the 5-year follow-up period. The hip implant remains stable with both bone preservation and loss 5 years after surgery.

A single-surgeon experience in reconstruction of femoro-acetabular offset and implant positioning in direct anterior approach and anterolateral MIS approach with a curved short stem

PURPOSE

Minimally invasive surgery using short stems in total hip arthroplasty gained more popularity. The differences in change of hip offset and implant positioning in minimally invasive approaches are not fully known. Therefore, this study was conducted to evaluate the difference in reconstruction of hip offset and implant positioning in direct anterior approach (DAA) and minimally invasive anterolateral approach (AL MIS).

METHODS

A single surgeon series of 117 hips (117 patients; mean age 65.54 years ± 11.47; index surgery 2014-2018) were included and allocated into two groups: group A (DAA) with 70 hips and Group B (AL MIS) with 47 patients operated. In both groups the same type of cementless curved short hip stem and press fit cup was used.

RESULTS

Both groups showed an equal statistically significant increase of femoral (p < 0.001) and decrease of acetabular offset (p < 0.001). Between both groups no statistically significant difference in offset reconstruction, leg length difference or implant positioning could be found. Leg length increased in both groups significantly and leg length discrepancy showed no difference (group A: - 0.06 mm; group B: 1.11 mm; p < 0.001). A comparable number of cups were positioned outside the target zone regarding cup anteversion.

CONCLUSION

The usage of a curved short stem shows an equal reconstruction of femoro-acetabular offset, leg length and implant positioning in both MIS approaches. The results of this study show comparable results to the existing literature regarding change of offset and restoration of leg length. Malposition of the acetabular component regarding anteversion poses a risk.

Short-term success of proximal bone stock preservation in short hip stems: a systematic review of the literature

Total hip arthroplasty is performed more frequently in younger patients nowadays, making long-term bone stock preservation an important topic. A mechanism for late implant failure is periprosthetic bone loss, caused by stress shielding around the hip stem due to different load distribution. Short stems are designed to keep the physical loading in the proximal part of the femur to reduce stress shielding. The aim of this review is to give more insight into how short and anatomic stems behave and whether they succeed in preservation of proximal bone stock.

A systematic literature search was performed to find all published studies on bone mineral density in short and anatomic hip stems. Results on periprosthetic femoral bone mineral density, measured with dual-energy X-ray absorptiometry (DEXA), were compiled and analysed per Gruen zone in percentual change.

A total of 29 studies were included. In short stems, Gruen 1 showed bone loss of 5% after one year (n = 855) and 5% after two years (n = 266). Gruen 7 showed bone loss of 10% after one year and –11% after two years. In anatomic stems, Gruen 1 showed bone loss of 8% after one year (n = 731) and 11% after two years (n = 227). Gruen 7 showed bone loss of 14% after one year and 15% after two years.

Short stems are capable of preserving proximal bone stock and have slightly less proximal bone loss in the first years, compared to anatomic stems.

Cite this article: EFORT Open Rev 2021;6:1040-1051. DOI: 10.1302/2058-5241.6.210030

Future of total hip arthroplasty with the Metha short stem in modern surgeries

The aim of the study was to analyse the results of uncemented total hip replacement, using the Metha (metaphyseal) stem. A total of 158 patients (70 females and 88 males) were qualified to the study and submitted to total hip arthroplasty (183 procedures altogether), using the Metha stem. The mean age of the patients on the day of surgery was 51.7 years (the range from 17 to 69 years). The mean follow up period was 9.2 years (the range from 5 to 13.5 years). Preoperative assessments gave poor scores, according to the Merle d’Aubigne and Postel classification, modified by Charnley. The average improvement after surgery, according to the used scale, was 6.9 points. A very good outcome was recorded in 154 cases (84.2%), a good outcome was achieved in 20 cases (10.9%) and a poor outcome was confirmed in 9 cases, while no satisfactory case was observed. Poor outcomes were associated with implant loosening. Extraskeletal ossification was noted in 10 cases (5.5%). According to the Kaplan–Meier estimator, the 10-year survival was 93.2% and 97.3% for the whole implant and the stem alone, respectively. 1. Our follow-up period of more than 9 years on the average, indicates that Metha stems produce excellent clinical and functional results in operated young patients with advanced degenerative changes of the hip joint. 2. Assuming a proper qualification for the procedure, the absence of complications and a correct surgical technique, which is slightly more difficult, when compared to standard stem implantation, the risk of aseptic loosening is fairly negligible.

Biomechanics of a calcar loading and a shortened tapered femoral stem: Comparative in-vitro testing of primary stability and strain distribution

Purpose

The most common femoral short stems available on the market can, in principle, be divided with regard to their anchoring concepts into a calcar loading and a shortened tapered design. The purpose of this study was to compare the primary stability and stress-shielding of two short stems, which correspond to these two different anchoring concepts.

Methods

Using seven paired fresh frozen human cadaver femurs, primary axial and rotational stabilities under dynamic load (100–1600 N) were evaluated by miniature displacement transducers after 100,000 load cycles. Changes in cortical strains were measured before and after implantation of both stem types to detect implant-specific load transmission and possible stress-shielding effects.

Results

Reversible and irreversible micromotions under dynamic load displayed no significant differences between the two implants. Implantation of either stem types resulted in a reduction of cortical strains in the proximal femur, which was less pronounced for the calcar loading implant.

Conclusions

Both short stems displayed comparable micromotions far below the critical threshold above which osseointegration may disturbed. Neither short stem could avoid proximal stress-shielding. This effect was less pronounced for the calcar loading short stem, which corresponds to a more physiological load transmission.

The migration pattern and initial stability of the Optimys short stem in total hip arthroplasty: a prospective 2-year follow-up study of 33 patients with RSA

BACKGROUND AND PURPOSE

The consensus that bone stock preservation and optimal restoration of offset and leg length is important in total hip arthroplasty is now widespread, especially for young and active patients. Short stems seem promising in this aspect, though implant stability is still of concern. This study looked at the migration pattern of the Optimys short stem through RSA analysis.

PATIENTS AND METHODS

40 patients were included. RSA images were made directly postoperatively (within 5 days), at 6 weeks and at 3, 6, 12 and 24 months. Double examinations were made for precision measurement. HOOS and pain scores were obtained preoperatively and at 2 years. 4 patients were excluded due to protocol violation and 1 patient was excluded for RSA analysis with a CN number >110. 2 patients were lost to follow-up after 3 and 6 months (n = 1 lost, n = 1 deep infection, respectively).

RESULTS

Mean age was 60 years with a mean BMI of 27. RSA analysis of 34 patients showed a significant initial median proximodistal translation (subsidence) of 0.21 mm (IQR 0.64-0.06) and anteversion-retroversion rotation of 0.59° (IQR 0.01-1.34) at 6 weeks, after which the stem stabilises and showed no further significant movement. Median migration in other directions was small. 4 patients had an initial subsidence of >2 mm, all showed secondary stabilisation. HOOS outcomes were satisfactory, with the domain symptoms and pain showing a median score of 95/100 at 2 years.

CONCLUSIONS

After initial migration the Optimys achieves secondary stabilisation, suggesting low risk on long-term aseptic loosening.

CLINICAL TRIALS REGISTRATION

NL47055.048.13.

Obesity in short stem total hip arthroplasty using a minimally invasive supine anterolateral approach-a risk factor for short-term complications?

Purpose

Obesity is associated with increased risk for surgical complications in total hip arthroplasty (THA). The impact of obesity on short-term complication in minimally invasive (MIS) anterolateral approach is not well known. Therefore, this study was conducted to evaluate the early complications within the first 90 days after THA using a MIS anterolateral approach with a short-curved stem stratified by Body Mass Index (BMI).

Patients and methods

A single centre consecutive series of 1052 hips in 982 patients (index surgery 2014–2019) with a short-curved stem and press fit cup implanted using a MIS anterolateral approach in supine position were screened for inclusion. Inclusion criteria were defined as end-stage primary osteoarthritis of the hip. Eventually, 878 implantations in 808 patients were included and stratified by body mass index (BMI). Peri-operative complications, within the first 90 days after surgery, were retrospectively evaluated.

Results

Severely obese patients (BMI ≥ 35 kg/m²) and morbidly obese patients (BMI ≥ 40 kg/m²) demonstrated a significantly increased operation time (p < 0.001) and a higher risk for general surgical complications (p = 0.015) (odds ratio (OR) = 4.365; OR = 4.985), periprosthetic joint infection (PJI) (p = 0.001) (OR = 21.687; OR = 57.653), and revision (OR = 8.793; OR = 20.708).

Conclusion

The risk for early PJI and overall surgical complications in MIS anterolateral approach is significantly increased in severely and morbidly obese patients. This leads to a significantly higher risk for revision surgery after index surgery within the first 90 days. A BMI above 35 kg/m² is the clear threshold for increased risk of PJI in MIS anterolateral THA with a short curved stem. As the surgical complications are comparable to other approaches, MIS anterolateral short stem THA is also feasible with increasing BMI.

Is diaphyseal fixation of short neck-retaining stem prostheses related to the size of the implant?

INTRODUCTION

Short-stem hip prostheses present variable proximal femoral bone radiological findings. The aims of this study were to analyse, in our patients with implanted collum femoris-preserving (CFP) stems, cancellous bone remodelling, cortical distal hypertrophy and pedestal formation, and the relationship between those radiological changes that suggest distal fixation with the size of the stem.

METHODS

From October 2001 to December 2012 a total of 199 consecutive primary total hip arthroplasties in 180 patients were performed at our department using the CFP stem and followed up for a minimum of 5 years until December 2017.

RESULTS

Stress shielding was present in 74% of oversized stems cases, but in normal or undersized stems, stress shielding was present in 8.5%. Cortical hyperthrophy was observed in 49% of the oversized stems and in 6% of the normal or undersized ones. Finally, non-statistically significant differences (p = 0.089) in pedestal formation were found, present in 16.3% of the oversized stems and in 6% of normal or undersized ones.

CONCLUSIONS

Oversized stems cause more stress shielding and distal cortical hypertrophy in the distal part of the stem, which indicates distal fixation in bigger sizes of stem.

Comparison of Clinical Outcomes, Radiological Outcomes and Bone Remodeling Outcomes Between Proximal Coated Single-Wedge New Stem and Full Coated Dual-Wedge Classic Stem in 1-Stage Bilateral Total Hip Arthroplasty

Background

This retrospective study investigated the clinical outcomes, radiological outcomes, and bone remodeling patterns associated with a Medial/Lateral Taper (M/L Taper) stem and Link Classic Uncemented (LCU) stem in 1-stage bilateral total hip arthroplasty (THA).

Material/Methods

The results of 52 patients who underwent 1-stage bilateral THA with a M/L Taper stem on one side and an LCU stem on the other between January 2012 and February 2015 were retrospectively compared. Patients were clinically assessed by the Harris hip score (HHS), visual analogue score (VAS) and incidence of complications. Radiological indicators were measured. Periprosthetic bone remodeling was assessed via bone mineral density (BMD) measurements.

Results

The mean follow-up time was 5.2 years. At each follow-up, there was no difference in the HHS and VAS between the 2 groups. The neck-shaft angle, offset, vertical height of the rotational center and limb lengthening were lower in the M/L Taper group than in the LCU group (P<0.001). The Engh total score was lower in the LCU group (P=0.039). Significantly higher (P<0.001) BMDs were observed in the M/L Taper group in Gruen zones 1, 2, and 6. significantly lower (P<0.001) BMDs were observed in the M/L Taper group in Gruen zones 3 and 5.

Conclusions

Due to the increased postoperative neck-shaft angle, the full coated dual-wedge classic stem was prone to cause lower limb lengthening. The proximal coated single-wedge new stem patients were more likely to have an insufficient postoperative neck length. The new stem achieved load transfer and proximal fixation, leading to better proximal femoral bone preservation is more in line with human biomechanical characteristics.

An Ultra-Short Femoral Neck-Preserving Hip Prosthesis: A 2-Year Follow-up Study with Radiostereometric Analysis and Dual X-Ray Absorptiometry in a Stepwise Introduction

BACKGROUND

Total hip arthroplasty (THA) with a diaphyseal stem may risk bone loss. In order to save proximal bone stock in young patients with a high activity level and a long life expectancy, the interest in short stems has evolved. The purpose of this prospective observational cohort study was to evaluate the fixation of, and bone remodeling around, the Primoris femoral neck-preserving hip implant.

METHODS

Fifty younger patients with end-stage osteoarthritis were managed with the Primoris hip implant. We evaluated bone mineral density (BMD) using dual x-ray absorptiometry (DXA) and implant migration using radiostereometric analysis (RSA). A region-of-interest (ROI) protocol for 4 ROIs was applied to assess BMD. The association between BMD and migration was evaluated to determine the fixation of the Primoris implant and bone remodeling in the proximal part of the femur. Follow-up evaluation was performed at regular intervals from day 1 (baseline) until 24 months after surgery.

RESULTS

The major stem migrations were subsidence (Y axis; mean, 0.38 mm) at 6 weeks and varus tilt (rotation) (Z axis; mean, 0.93°) at 6 to 12 months. In ROI4 (the calcar area), a significant gain in bone was found with a mean difference of 4.1% (95% confidence interval [CI], 0.8% to 7.4%; p < 0.02) at 24 months postoperatively. Significant bone loss was found in ROI1 and ROI2, with a mean difference of -4.9% (95% CI, -7.4% to -2.4%; p = 0.0003) and -8.9% (95% CI, -11.5% to -6.2%; p = 0.0001), respectively. Linear regression and multivariate regression analysis showed a significant negative association between maximal total point motion and BMD (p = 0.02, R = 15%; and p < 0.05, R = 26%, respectively).

CONCLUSIONS

The Primoris component showed satisfactory primary stability with promising results at the 24-month follow-up. DXA scans showed limited stress-shielding with the proximal loading pattern of the Primoris. Better bone quality was associated with less implant migration.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.

Cementless short-stem total hip arthroplasty in the elderly patient - is it a safe option?: a prospective multicentre observational study

Background

Due to its bone preserving philosophy, short-stem total hip arthroplasty (THA) has primarily been recommended for young and active patients. However, there may be benefits for elderly patients given a less invasive operative technique due to the short curved implant design. The purpose of this study was to compare the clinical and radiological outcomes as well as perioperative complications of a calcar-guided short stem between a young (< 60 years) and a geriatric (> 75 years) population.

Methods

Data were collected in a total of 5 centers, and 400 short-stems were included as part of a prospective multicentre observational study between 2010 and 2014 with a mean follow-up of 49.2 months. Preoperative femur morphology was analysed using the Dorr classification. Clinical and radiological outcomes were assessed in both groups as well as perioperative complications, rates and reasons for stem revision.

Results

No differences were found for the mean visual analogue scale (VAS) values of rest pain, load pain, and satisfaction, whereas Harris Hip Score (HHS) was slightly better in the young group. Comparing both groups, none of the radiological parameters that were assessed (stress-shielding, cortical hypertrophy, radiolucency, osteolysis) reached differences of statistical significance. While in young patients aseptic loosening is the main cause of implant failure, in the elderly group particularly postoperative periprosthetic fractures due to accidental fall have to be considered to be of high risk. The incidence of periprosthetic fractures was found to be 0% in Dorr type A femurs, whereas in Dorr types B and C fractures occurred in 2.1 and 22.2% respectively.

Conclusions

Advanced age alone is not necessarily to be considered as contra-indications for calcar-guided short-stem THA, although further follow-up is needed. However, markedly reduced bone quality with femur morphology of Dorr type C seems to be associated with increased risk for postoperative periprosthetic fractures, thus indication should be limited to Dorr types A and B.

Trial registration

German Clinical Trials Register; DRKS00012634, 07.07.2017 (retrospectively registered).

Periprosthetic Bone Mineral Density Around Uncemented Titanium Stems in the Second and Third Decade After Total Hip Arthroplasty: A DXA Study After 12, 17 and 21 Years

Implant failure and periprosthetic fractures because of periprosthetic bone loss are a major concern in total hip arthroplasty (THA). Hardly any clinical data exist on the long-term evolution of bone mineral density (BMD) around uncemented femoral implants. The question to address is whether relevant bone loss continues into third decade around well-fixed uncemented femoral implants. BMD around stable uncemented straight titanium femoral implants was assessed in a longitudinal cohort study. We included 142 hips of 128 patients and measured the development of the periprosthetic BMD using dual-energy X-ray absorptiometry. The baseline measurement was 12 years (t₁) after the implantation of an uncemented femoral stem. Follow-up-measurements were performed at 17 (t₂) and at 21 years (t₃) after primary THA. The regions of interest (ROI) were selected conforming to Gruen et al. We acquired complete data including three consecutive measurements (t₁, t₂, t₃) for 42 patients (49 hips). Performing radiographic evaluation at t₁, t₂ and t₃, we found a regular bone-implant interface present in all cases. Significant decrease in BMD could be shown in ROI 1 (p = 0.0001; - 7.8%), 4 (p = 0.024; - 2.4%), 6 (p = 0.001; - 5.5%) and 7 (p < 0.0001; - 11.7%) between t₁ and t₃ and in ROI 1 (p = 0.002; - 3.7%), 2 (p = 0.046; - 3.6%), 4 (p = 0.002; - 2.7%) and 7 (p < 0.0001; - 8.0%) between t₂ and t₃. There were significant differences in overall bone density (netavg) between t₁ and t₃ (p = 0.001; - 3.6%) and between t₂ and t₃ (p = 0.020; - 2.1%). The data indicate clinically relevant changes of BMD especially in the proximal Gruen zones in the long-term after uncemented THA. Loss of periprosthetic BMD might be a risk factor for periprosthetic fractures.

Are short-stem prostheses superior to conventional stem prostheses in primary total hip arthroplasty? A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

Cementless total hip arthroplasty (THA) is associated with reliable clinical results and high patient satisfaction. Short-stem prostheses (SS) were designed to achieve superior preservation of proximal bone stock and stability compared with those of conventional-stem prostheses (CS). This meta-analysis was conducted to determine the proximal bone remodelling, revision rate, Harris Hip Score, radiolucent line and maximum total point motion values of both SS and CS for primary THA.

METHOD

Relevant randomised controlled trials (RCTs) involving SS and CS in primary THA were identified from electronic databases, such as EMBASE, PubMed and the Cochrane Library.

RESULT

Ultimately, 12 RCTs involving 1130 patients (1387 hips) were included. The results showed that compared with CS, SS resulted in less bone mineral density (BMD) changes in Gruen zone 7 at 1 year and 2 years postoperatively (mean difference (MD)=5.11; 95% CI, 1.61, 8.61; P=0.30; and MD=4.90; 95% CI, 1.01, 8.79; P=0.17, respectively). No difference in BMD changes was found for Gruen zone 1 (MD=2.66; 95% CI, -3.31, 8.64; P<0.00001), and no differences were observed for the revision rate (relative risk (RR)=1.52; 95% CI, 0.71, 3.26; P=0.94), Harris Hip Score (MD=-0.38; 95% CI, -1.02, 0.26; P=0.89) or stem migration (MD=0.02; 95% CI, -0.07, 0.11; P=0.04).

CONCLUSION

Our results suggest that compared with CS, SS may provide superior bone remodelling and similar survival rates and clinical outcomes. However, the short-term follow-up of the included studies was inadequate to determine the long-term performance of SS.

Development of periprosthetic bone mass density around the cementless Metha® short hip stem during three year follow up-a prospective radiological and clinical study

PURPOSE

The purpose of this study was to check the concept of the cementless Metha® short hip stem in order to find out whether proximal physiological load transfer can be achieved.

METHODS

Fourty-three patients were included. Epidemiological factors were established. The Harris Hip Score was determined and measurement of bone mass density as well as osteodensitometric and radiological measurements was carried out pre-operatively, post-operatively, and after six, 12, 24, and 36 months.

RESULTS

Harris Hip Score improved from 55.9 ± 12.4 pre-operatively to 94.8 ± 8.2 after 36 months (p < 0.001). After initial reduction of bone density in zones 1 and 7 up to six months post-operatively, there was a steady approximation of bone density to the initial values (p < 0.05).

CONCLUSION

The Metha® short hip stem shows good clinical results. Furthermore, there is an increase of bone density in the proximal zones 1 and 7 between six and 36 months serving as a sign of physiological load transfer.

Uncemented short stems in primary total hip arthroplasty: The state of the art

Over the last two decades, several conservative femoral prostheses have been designed. The goals of conservative stems include: the spearing of the trochanteric bone stock; a more physiological loading in the proximal femur reducing the risk of stress shielding; and to avoid a long stem into the diaphysis preventing impingement with the femoral cortex and thigh pain.

All stems designed to be less invasive than conventional uncemented stems are commonly named ‘short stems’. However, this term is misleading because it refers to a heterogeneous group of stems deeply different in terms of design, biomechanics and bearing. In the short-term follow-up, all conservative stems provided excellent survivorship. However, variable rates of complications were reported, including stem malalignment, incorrect stem sizing and intra-operative fracture.

Radiostereometric analysis (RSA) studies demonstrated that some conservative stems were affected by an early slight migration and rotation within the first months after surgery, followed by a secondary stable fixation. Dual-energy x-ray absorptiometry (DEXA) studies demonstrated an implant-specific pattern of bone remodelling.

Although the vast majority of stems demonstrated a good osseointegration, some prostheses transferred loads particularly to the lateral and distal-medial regions, favouring proximal stress shielding and bone atrophy in the great trochanter and calcar regions.

Cite this article: EFORT Open Rev 2018;3:149-159. DOI: 10.1302/2058-5241.3.170052

Periprosthetic bone remodeling of short cementless femoral stems in primary total hip arthroplasty: A systematic review and meta-analysis of randomized-controlled trials

BACKGROUND

Short-stem total hip arthroplasty (SHA) has been increasingly used in the treatment of hip arthroplasty. However, it is unclear whether there is a superiority of SHA in periprosthetic bone remodeling over standard stem total hip arthroplasty (THA). This meta-analysis of randomized-controlled trials (RCTs) compared the periprosthetic bone remodeling after SHA and THA.

METHODS

PubMed and Embase were screened for relevant publications up to May 2017. RCTs that compared periprosthetic bone remodeling with bone mineral density (BMD) changes between SHA and THA were included. Meta-analysis was conducted to calculate weighted mean differences (WMDs) and 95% confidence intervals (CIs) using Stata version 12.0. Quality appraisal was performed by 2 independent reviewers using RevMan 5.3 software and Grades of Recommendation Assessment, Development, and Evaluation criteria.

RESULTS

Seven studies involving 910 patients and 5 SHA designs (Proxima, Fitmore, Microplasty short, Unique custom, and Omnifit-HA 1017) were included for meta-analysis. The pooled data showed no significant differences in the percentage BMD changes in all Gruen zones, with Gruen zone 1 [mean difference (MD) = 11.33, 95% CI, -1.67 to 24.33; P = .09] and Gruen zone 7 (MD = 8.46, 95% CI, -1.73 to 18.65; P = .10). Subgroup analysis of short SHA stems with lateral flare showed a significant less percentage BMD changes compared with standard THA in Gruen zone 1 (MD = 27.57, 95% CI, 18.03-37.12; P < .0001) and Gruen zone 7 (MD = 18.54, 95% CI, 8.27-28.81; P < .0001).

CONCLUSION

The study shows moderate-quality evidence that periprosthetic bone remodeling around the analyzed SHA stems was similar to standard THA stems. However, short SHA stems with lateral flare revealed a moderate- to low-quality evidence for superiority over the standard THA and highlighted the importance of the different SHA designs. Besides, it has to be noticed that despite a similar pattern of periprosthetic bone remodeling, the femoral length where periprosthetic bone remodeling occurs is clearly shorter in SHA. Due to the moderate- to low-quality evidence and the limited stem designs analyzed, the further large-scale multicenter RCTs including the most recent SHA designs are required. However, the current findings should be considered by surgeons for counseling patients regarding total hip replacement.

Bone remodelling around the Metha® short stem implant - Clinical and dual-energy x-ray absorptiometry (DXA) results

OBJECTIVE

Bony ingrowth of short stems is under investigation.

METHOD

Over one year bony reactions around the Metha^® stem were investigated using the DXA method in a standardized zonal system (19 ROIs). Clinical results were documented using the HHS.

RESULTS

HHS significantly improved from 46 points to 97 points. After one year bone marrow density (BMD) increased in the lateral distal and lateral proximal areas as well as in the mid medial area. BMD decreased in the proximal medial and mid lateral areas.

CONCLUSION

The concept of metaphyseal ingrowth was confirmed, but distal bony reactions need further investigation.

Early performance-based and patient-reported outcomes of a contemporary taper fit bone-conserving short stem femoral component in total hip arthroplasty

Aims

The aim of this study was to compare early functional and health related quality of life outcomes (HRQoL) in patients who have undergone total hip arthroplasty (THA) using a bone conserving short stem femoral component and those in whom a conventional length uncemented component was used. Outcome was assessed using a validated performance based outcome instrument as well as patient reported outcome measures (PROMs).

Patients and Methods

We prospectively analysed 33 patients whose THA involved a contemporary proximally porous coated tapered short stem femoral component and 53 patients with a standard conventional femoral component, at a minimum follow-up of two years. The mean follow-up was 31.4 months (24 to 39). Patients with poor proximal femoral bone quality were excluded. The mean age of the patients was 66.6 years (59 to 77) and the mean body mass index was 30.2 kg/m2 (24.1 to 41.0). Outcome was assessed using the Oxford Hip Score (OHS) and the University College Hospital (UCH) hip score which is a validated performance based instrument. HRQoL was assessed using the EuroQol 5D (EQ-5D).

Results

There were no major peri-operative complications. There was no difference in the mean post-operative OHS, EQ-5D or function subscale of the UCH hip scores between the two groups. The mean pre-operative OHS and EQ-5D scores improved significantly (all p <  0.001). The mean functional component of the UCH hip score at final follow-up was 42.5 and 40.6 in the short stem and conventional stem groups, respectively. There was no statistically significant difference between the groups (p = 0.42). A total of seven patients (21.2%) in the short stem group and nine (16.98%) in the conventional group achieved a ceiling effect using the OHS; none did using the function subscale of the UCH hip score.

Conclusion

The proximally porous coated tapered short stem femoral component achieves comparable short-term functional outcomes when compared with a conventional longer stem uncemented femoral component when THA is undertaken in patients with good bone quality. Cite this article: Bone Joint J 2017;99-B(4 Supple B):49–55.

No Difference in Periprosthetic Bone Loss and Fixation Between a Standard-Length Stem and a Shorter Version in Cementless Total Hip Arthroplasty. A Randomized Controlled Trial

BACKGROUND

Cementless femoral stems in total hip arthroplasty provide dependable clinical and radiographic results in the treatment of osteoarthritis. Stem length might affect the preservation of proximal bone stock and stability. We hypothesized that a shorter stem decreases proximal bone loss without affecting implant stability.

METHODS

We randomly assigned 60 patients aged between 50 and 70 years to either a standard cementless femoral stem or a 35-mm shorter version. Patients were followed with dual-energy X-ray absorptiometry, radiostereometric analysis, Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index score, and clinical follow-up at 3, 6, 12, and 24 months. The trial is registered on ClinicalTrials.gov/.

RESULTS

After 24 months, short stems had on average 3.8% (95% confidence interval, 1.2%-8.9%) more bone loss in zone 1 compared to standard stems (P = .14). In zone 7, the bone loss was on average 6.5% (95% confidence interval, 6.6%-19.7%) higher compared to standard stems (P = .33). After 24 months, standard stems had migrated 0.93 mm (range, 0.25-4.66 mm) and short stems 0.93 mm (range, 0.17-2.96 mm; Student t-test after log transformation, P = .3). Patient-reported outcome measures were similar in both groups. One patient in the standard stem group was diagnosed with infection, one with a posterior dislocation, and one with a deep venous thrombosis. No stems were revised.

CONCLUSION

There were no statistically significant differences in periprosthetic bone loss or fixation between the stems at 24 months.

Periprosthetic Bone Remodeling After Novel Short-Stem Neck-Sparing Total Hip Arthroplasty

BACKGROUND

Short femoral stems have been designed with the aims of reducing proximal bone loss, improving load transfer, and increasing compressive loads at the medial proximal femoral calcar. This study examines bone mineral density (BMD) changes associated with a novel neck sparing short femoral stem design.

METHODS

The study was a prospective, single-center, multi-investigator consecutive series, which assessed bone-remodeling changes after insertion of the MSA Stem (Global Orthopaedic Technology). Dual-energy X-ray absorptiometry scans were performed preoperatively and postoperatively at 6, 12, and 24 months assessing the BMD at the 7 Gruen zones. The secondary objectives assessed were the Harris Hip Score, 12-Item Short Form Health Survey preoperatively, and perioperative complications.

RESULTS

Thirty-nine total hip arthroplasties were performed on 37 patients, with 27 patients completing the 24-month dual-energy X-ray absorptiometry scan. The overall preoperative baseline BMD was 0.2. At 6 months, the Gruen zone BMD had increased significantly in all zones in comparison to the preoperative mean BMD. Between 6 months and 24 months, there were only slight changes in the Gruen zones, with small gains in zones 1-2 and zones 4-6, with no zone showing a significant decrease. The Harris Hip Score improved from a preoperative mean of 39.7-75.3, whereas the 12-Item Short Form Health Survey score also improved from 32.6 to 49 at 24 months. However, 5 patients had aseptic loosening requiring revision surgery (4 femoral and 1 acetabular component).

CONCLUSION

Short-stem neck-sparing femoral stem prosthesis has the capacity to address the stress-shielding problem identified in femoral stems. However, the high early revision rate is a significant issue.