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

Long-term outcomes of the mayo conservative hip system in patients aged 30 years or less with osteonecrosis of the femoral head: mean follow-up of more than 10 years

INTRODUCTION

Historically, total hip arthroplasty (THA) in very young patients has been associated with lower survivorship. However, the long-term outcomes of THA using short stems for osteonecrosis of the femoral head (ONFH) in very young patients remain unclear. Therefore, this study aimed to investigate the long-term outcomes of the Mayo conservative hip system, a short metaphyseal stabilised stem, in patients with ONFH aged ≦30 years.

MATERIALS AND METHODS

We retrospectively reviewed 104 joints in 76 patients with ONFH who underwent THA using the Mayo conservative hip system with a minimum follow-up of 8 years. The mean follow-up period was 12.5 (range, 8-19) years. Patients were categorised into two age groups (≦30 years, n = 21 and > 30 years, n = 83). Radiographic evaluation was used to assess stem sinking, stress shielding, and spot welds. The clinical evaluations were performed using the Japanese Orthopedic Association (JOA) hip score. Postoperative major complication and revision surgery rates were also assessed.

RESULTS

The patient characteristics were similar between the two groups, except for the age. Revision surgeries were performed in five cases, with similar implant survival rates between the groups. Dislocations occurred in the older age group alone (four joints). One case of intra-operative periprosthetic femoral fracture was found in the younger age group. Stem sinking of > 3 mm occurred in one and seven joints in the younger and older age groups, respectively. Spot welds were observed in most joints (93.2%) in modified Gruen zones 2 and 6 without significant differences between the groups. Stress shielding showed no significant differences in the frequency of occurrence or location between the two groups. Furthermore,the JOA score showed no significant difference between the two groups.

CONCLUSION

The use of short stems in patients aged ≤ 30 years with ONFH showed favourable long-term outcomes.

Total Hip Replacement with a Fully Hydroxyapatite-Coated Shortened Stem: Five- to Thirteen-Year Follow-Up Results

Background: Shortened femoral stems aim to mimic the biomechanical performance of traditional stems while preserving more bone and minimizing soft tissue damage. Our objective is to assess the outcomes of patients treated with a shortened stem (Furlong Evolution, JRI Orthopaedics, Sheffield, UK) to analyze the implant's efficacy and survivorship. Methods: This retrospective observational study included all patients aged 18 to 70 undergoing uncemented shortened stem total hip replacement at Hospital del Mar between 2010 and 2018. Hip function and pain were assessed with the Merle d'Aubigné-Postel scale and visual analog scale, respectively. A radiographic analysis measured stem and cup orientation, leg length discrepancy, stem subsidence, and radiolucencies around the cup. Perioperative complications, prosthetic failures, and reoperations were documented. Results: A total of 109 patients (74 male, 35 female) of a mean age of 51.8 ± 8.8 years were included. The average follow-up was 91 ± 17.4 months. Radiographically, 71 (65.1%) of the stems had been inserted at the appropriate angulation (±3°), and 102 (93.6%) of the cups had been placed in the Lewinnek safety zone. Leg length discrepancy was observed in 19 (17.4%) cases. The mean Merle d'Aubigné-Postel score improved from 13.1 ± 1.39 preoperatively to 17.8 ± 0.49 at 6 months postoperatively (p < 0.001). Merle d'Aubigné-Postel subscales also reflected a statistically significant improvement (p < 0.001). The mean pain score 12 months postoperatively was 0.52 ± 1.22, with 95.4% of patients declaring themselves satisfied or highly satisfied. The expected 13-year survival according to a Kaplan-Meier analysis was 100% in the absence of infection and 91.3% if revision for any cause is taken as a survival endpoint. Conclusions: The shortened stem under analysis provides excellent functional results and long-term survival rates.

Early- to mid-term outcome of a short, cementless, titanium, flat, tapered stem for primary total hip arthroplasty: an independent series

INTRODUCTION

This study aims to: (1) describe perioperative complications amongst patients who underwent primary total hip arthroplasty (THA) using a short cementless, titanium, flat, tapered stem; (2) estimate this stem's early- to mid-term survival; (3) identify factors associated with revision arthroplasty; and (4) describe femoral remodelling at minimum 6 years postoperatively.

METHODS

A retrospective review of consecutive patients who underwent THA using a Taperloc Microplasty stem (Zimmer-Biomet, Warsaw, Indiana, USA) with minimum 2-year follow-up was performed. Surgeries were performed by 1 of 6, non-designer, arthroplasty surgeons between 2014 and 2018. Outcomes included perioperative complications including revision arthroplasty, and survival. Cox analysis was used to analyse the effect of different factors on risk of revision arthroplasty. Radiographs with 6-year follow-up served to describe femoral remodelling.

RESULTS

In 1205 patients, followed for 5.1 ± 1.4 years, the incidence of perioperative complication was 5.2% for which 29 patients (2.4%) required revision arthroplasty. The 5- and 7-year survival rates were 97.8% (95% CI, 96.9-98.5) and 97.0% (95% CI, 95.6-98.0), respectively. The only factor associated with revision arthroplasty was proximal femur morphology, as per Dorr classification (HR 1.24 [95%CI, 1.09-1.41]; p = 0.005). During radiographic assessment, 12% of patients showed ⩾25% of relative change in cortical thickness in Gruen zones 3 or 5. We observed calcar remodelling in 50% of radiographs while 10% showed presence of a pedestal sign.

CONCLUSIONS

The 7-year survivorship of the Taperloc Microplasty stem is within National Institute for Health and Care Excellence (NICE) guidelines. Patients ⩽65 years with osteoarthritis and Dorr A/B femoral morphology may be ideal candidates for THA with this stem. Femoral remodelling is common and not associated with adverse outcome.

Subsidence after calcar-guided short stem total hip arthroplasty: five-year results of a prospective multicentre study

PURPOSE

Calcar-guided short-stem total hip arthroplasty (THA) has shown excellent clinical outcomes. However, the migration pattern of such prostheses and its effect on clinical outcomes are less known. Therefore, we assessed the five-year subsidence after calcar-guided short-stem THA and its implications on clinical outcomes, patient-related factors, and complications.

METHODS

In this prospective multicentre study, we enrolled 213 patients (224 hips) who underwent calcar-guided short-stem THA mostly for degenerative hip diseases. We examined patients radiographically and clinically after six to 12 weeks, one year, two years, and five years. We evaluated subsidence using Einzel-Bild-Roentgen-Analyse femoral component analysis, assessed clinical outcomes, and systematically recorded all complications.

RESULTS

Overall, 131 patients (133 hips) were available for final follow-up at a median of 60 months (range, 2 to 72 months). We found a mean subsidence of 0.63 ± 1.22 mm at three months, 1.03 ± 1.60 mm at one year, 1.21 ± 1.91 mm at two years, and 1.54 ± 1.97 mm at five years. Patient-related factors (sex, age, weight, and BMI) did not significantly impact subsidence at five years (P > 0.05). Additionally, the Harris hip score, pain, and satisfaction improved significantly at five years compared to pre-operative values (P < 0.0001). Lastly, five patients underwent revision.

CONCLUSION

Calcar-guided short-stems revealed the highest subsidence rate within the first three months after THA and stabilisation after one year through the final follow-up examination. Moreover, patient-related factors had no influence on subsidence. Finally, clinical scores and patient satisfaction remained high at five years.

Do hip resurfacing and short hip stem arthroplasties differ from conventional hip stem replacement regarding impingement-free range of motion?

Total hip joint replacement (THR) is clinically well-established. In this context, the resulting range of motion (ROM) is crucial for patient satisfaction when performing joint movements. However, the ROM for THR with different bone preserving strategies (short hip stem and hip resurfacing) raises the question of whether the ROM is comparable with conventional hip stems. Therefore, this computer-based study aimed to investigate the ROM and type of impingement for different implant systems. An established framework with computer-aided design 3D models based on magnetic resonance imaging data of 19 patients with hip osteoarthritis was used to analyse the ROM for three different implant systems (conventional hip stem vs. short hip stem vs. hip resurfacing) during typical joint movements. Our results revealed that all three designs led to mean maximum flexion higher than 110°. However, hip resurfacing showed less ROM (-5% against conventional and -6% against short hip stem). No significant differences were observed between the conventional and short hip stem during maximum flexion and internal rotation. Contrarily, a significant difference was detected between the conventional hip stem and hip resurfacing during internal rotation (p = 0.003). The ROM of the hip resurfacing was lower than the conventional and short hip stem during all three movements. Furthermore, hip resurfacing shifted the impingement type to implant-to-bone impingement compared with the other implant designs. The calculated ROMs of the implant systems achieved physiological levels during maximum flexion and internal rotation. However, bone impingement was more likely during internal rotation with increasing bone preservation. Despite the larger head diameter of hip resurfacing, the ROM examined was substantially lower than that of conventional and short hip stem.

Battle of the titans: Survivorship analysis of the 3 most common types of uncemented femoral stems used across national registries

Background

Although many institutions utilize uncemented stems as routine in performing total hip arthroplasty (THA), many surgeons continue to rely on outcomes reported in the literature in the form of small cohorts and patient series when analyzing survivorship for specific implants. The purpose of this study was to identify and analyze the survivorship of the 3 most common uncemented stem types (as opposed to brands) used across multiple national joint registries.

Methods

A review of data available from all national joint registries was carried out in July 2022. Analysis of each individual registry and classified uncemented implants into the seven different uncemented stem types. The 3 most common stem types were identified, and average cumulative revision rates calculated. Metal on metal bearings surface implants were excluded from this study due to high revision rates across all implant types.

Results

Our detailed review identified 6 out of 13 (NJR, AOANJRR, LROI, EPRD, MARCQI and the NZJR) international registries reporting implant specific survivorship on uncemented femoral stems; including 960,328 uncemented stems across all registries. The most common type of stem used was type 3c, accounting for 61% (583,724), followed by type 1 stems with 23% (217,897) and type 2 stems with 8% (79,257). Cumulative revision rates at 13 years follow-up for these stems ranged from 6.9% to 7.9%.

Conclusion

Although all stem types have comparable revision rates across all registries, the most common uncemented stem reported was the type 3c, tapered rectangular fully coated stem. Furthermore, out of all type 3c, the Müller design philosophy with full hydroxyapatite coating seems to be the most sought after worldwide. In this study we can conclude, thus far, that there does not appear to clinical or statistical differences in revision rates between the different stem types.

Level of evidence

III.

Intermediate-Term Survivorship of Total Hip Arthroplasty With a Proximally Coated Tapered-Wedge Femoral Stem: A Retrospective, Multi-Center Registry Review

BACKGROUND

Short tapered-wedge stems have been used frequently over the past decade, but long-term follow-up data are not readily available in the literature.

METHODS

A retrospective outcomes review was conducted to assess survivorship and clinical outcomes for the TRI-LOCK® Bone Preservation Stem (TRI-LOCK BPS; DePuy Synthes, Warsaw, IN, USA), a proximally coated, tapered-wedge femoral stem.

RESULTS

In a cohort of 2,040 hips, Kaplan-Meier survivorship estimates (95% CI {confidence interval}; N with further follow-up, where N is the number of hips remaining at each post-operative interval), with survivorship defined as no revision of any component for any reason were 96.6% (92.8%,98.4%; 45) at eight years under the clinical assumption and 98.6% (97.9%,99.1%; 90) at 14 years under the registry assumption. With survivorship defined as stem revision for any reason, estimates were 97.7% (93.7%,99.2%; 45) at eight years under the clinical assumption and 99.2% (98.6%,99.5%; 90) under the registry assumption. Mean Harris Hip Scores and WOMAC scores were 90.08 and 21.98, respectively, at 10 years postoperatively.

CONCLUSION

Our evaluation demonstrates excellent construct and stem survivorship and clinical outcomes at intermediate-term postoperative follow-up.

Biomechanical Properties of Bionic Collum Femoris Preserving Hip Prosthesis: A Finite Element Analysis

OBJECTIVE

Compared with total hip replacement, conventional collum femoris preserving prosthesis has a better bone retention effect. However, damage to the trabecular bone of the proximal femur leads to inevitable abnormal stress distribution, which leads to increased risks of femoral neck bone absorption, periprosthetic fracture, prosthesis loosening, rotation, and sinking. Thus, we compare the biomechanical properties of collum femoris preserving (CFP) and bionic collum femoris preserving (BCFP) hip prostheses.

METHODS

The Sawbone digital model (#3503, left, medium) was selected as the research object. We used the Mimics 21.0 software to reconstruct the digital model of the femur and the SolidWorks 2019 software to build and assemble the three-dimensional models of CFP and BCFP prostheses. With the ANSYS Workbench 2021R1 software, the models were meshed and assigned values to simulate the load of a single foot under slow walking. We measured the mechanical distribution of the whole model and obtained the stress nephogram.

RESULTS

For CFP prosthesis, the peak stresses of the medial interface of the stem neck, the lateral interface of the stem neck, and the end of the stem were 64.894, 32.199, and 8.578 MPa, respectively; the peak stresses of the medial surface of the femoral shaft, the lateral surface of femoral shaft, the medial femoral neck bone-prosthesis interface (osteotomy interface), the lateral femoral neck bone-prosthesis interface (basal area), the lateral femoral neck bone-prosthesis interface (osteotomy interface), and the greater trochanter area were 28.093, 24.790, 14.388, 5.118, 4.179, and 8.245 MPa, respectively; the valley stress of the greater trochanter area was 1.134 MPa. For BCFP prosthesis, the peak stresses of the medial interface of the stem neck, the lateral interface of the stem neck, and the end of the stem were 47.015, 26.771, and 47.593 MPa, respectively; the peak stress of tension screw was 15.739 MPa; the peak stresses of the medial surface of the femoral shaft, the lateral surface of femoral shaft, the medial femoral neck bone-prosthesis interface (osteotomy interface), the lateral femoral neck bone-prosthesis interface (basal area), the lateral femoral neck bone-prosthesis interface (osteotomy interface) and the greater trochanter area were 28.581, 25.364, 15.624, 6.434, 4.986, and 8.796 MPa, respectively; the valley stress of the greater trochanter area was 1.419 MPa; the peak stress of bone-metal interface between the tension screw and the lateral surface of the femur was 5.858 MPa.

CONCLUSION

Compared with the CFP prosthesis, the design of the BCFP prosthesis is based on the lever balance theory. With the bionic reconstruction of tension trabeculae, BCFP prosthesis makes up for the defects of CFP prosthesis design, optimizes the stress distribution, and reduces the stress shelter effect of the proximal femur, which has better biomechanical properties.

Midterm results of the Birmingham hip resurfacing: a single-surgeon series

INTRODUCTION

Birmingham hip resurfacing (BHR) is readily used as alternative to total hip replacement in younger patients. The current study aims to compare outcomes in terms of adverse local tissue reactions (ALTR), elevated metal ion levels and survival rates between low-risk (femoral component size ≥ 48 mm) and high-risk (femoral component size < 48 mm) BHR patients at a minimum 5-year follow-up (FU).

MATERIALS AND METHODS

We report the minimum 5-year, single surgeon outcome results of 183 BHRs, performed between 2007 and 2012. 154 patients, 18 women (20 hips) and 136 men (163 hips) were included in the study. Patients were grouped in 149 low-risk cases (femoral component size ≥ 48 mm) and in 34 high-risk cases (18 female/12 male) patients with a femoral head size < 48 mm).

RESULTS

At a minimum of 5-years FU time, 91% of the patients were available for FU. The overall survival rate was 91.8%. There were five revisions (survival rate 96.6%) in the low-risk group and ten revisions (survival rate 70.6%) in the high-risk group. In the low-risk group, six patients (6.5%) showed elevated metal ion levels (> 7 μg/l), compared to five patients (20.8%) in the high risk-group (p = 0.03).

CONCLUSION

Including the surgeon's initial learning curve, the BHR shows very good mid-term survival rates in the low-risk group but should, as previously demonstrated, not be considered for patients with less than 48 mm femoral head size.

LEVEL OF EVIDENCE

Level III: retrospective cohort study.

Simultaneous Bilateral Total Hip Arthroplasty with Straight-Stems and Short-Stems: Does the Short One Do a Better Job?

BACKGROUND

Total hip arthroplasty (THA) is known to be the most successful orthopaedic surgery of the last century, but it is still struggling with controversies concerning one-stage bilateral THA. The current study aimed to compare the clinical outcome of patients with unilateral or simultaneous bilateral THA by using short-stem and straight-stem designs and focusing on operation time, blood loss, and length of hospital stay (LOS).

MATERIAL AND METHODS

Between 2006 and 2018, 92 patients were enrolled in this study. Forty-six patients underwent a bilateral THA in one session, and forty-six matched patients underwent a unilateral THA. In each of the two groups (unilateral vs. bilateral), 23 patients received either a straight (unilateral: 10 females, 13 males, mean age 63; bilateral: 12 females, 11 males, mean age 53 years) or short stem (unilateral: 11 females, 12 males, mean age 60 years; bilateral: 12 females, 11 males, 53 mean age 62 years). The blood count was checked preoperatively as well as one and three days after surgery. Furthermore, the operation time and LOS were investigated.

RESULTS

Compared to THA with straight-stems, short-stem THA showed significantly less blood loss; there was no difference in the LOS of both groups. A significantly shorter operative time was only observed in the bilateral THA.

CONCLUSION

The current study showed that simultaneous bilateral THA appears to be safe and reliable in patients without multiple comorbidities. In addition, short-stem THA appears to be beneficial in terms of clinical performance and outcome, and it appears to be superior to straight-stem THA, regardless of whether the patient underwent unilateral or simultaneous bilateral THA.

Restoration of hip geometry after total hip arthroplasty: retrospective comparison of two short stems and one straight stem

BACKGROUND

The preservation or restoration of hip geometry following total hip arthroplasty (THA) is of importance, considering that alterations in the centrum-collum-diaphysis (CCD)-angle, femoral offset (FO), acetabular offset (AO) and total offset (TO) change hip biomechanics. Therefore, the most suitable implant should be used. The aim of this study was to compare the ability of two short-stem-systems and one straight-stem-system to reconstruct hip geometry.

METHODS

Two-hundred-fifty-one patients (mean age: 62.0 ± 10.0 years; 51.8% males) undergoing THA with three different stem types were retrospectively included, after excluding 11 patients with missing radiological follow-up. Pre- and postoperative radiographic images (group I, ANA.NOVA Alpha Schaft Proxy®, ImplanTec, 12 options: n = 99; group II, Optimys® Mathys, 24 options: n = 62; group III: Corail®-System, DePuy-Synthes, 76 options: n = 90) were analyzed. Differences in pre- and postoperative hip geometry (i.e. CCD, FO, AO, TO) were compared between groups with one-way-analysis-of-variance (ANOVA), and post-hoc t-tests.

RESULTS

The CCD-angle increased by a mean of 8.4° ± 7.2° from pre-to postoperative, with no significant difference between groups (p = 0.097). Significantly larger increases in FO were observed for groups II (4.1 mm ± 7.8 mm) and III (4.9 ± 7.2 mm), in comparison to group I (1.6 ± 6.9 mm; p = 0.006). AO decreased by a mean of 2.2 ± 4.5 mm, with the largest decrease observed in group III (-3.3 ± 5.3 mm), and the smallest for group I (-1.4 ± 3.6 mm; p = 0.011). There was no significant difference in change of TO between groups (p = 0.177).

CONCLUSIONS

Reconstruction of hip geometry using a single-version novel short-stem-system is achievable with comparable results to stem-systems offering multiple options.

Three-year migration analysis of a new metaphyseal anchoring short femoral stem in THA using EBRA-FCA

Cementless calcar-guided femoral short stems in total hip arthroplasty (THA) have become increasingly popular over the years. Early distal migration of femoral stems measured by Einzel-Bild-Roentgen Analyse, Femoral Component Analyse (EBRA-FCA) has been reported to be a risk factor for aseptic loosening. The aim of this study was to analyse axial migration behavior and subsidence of a new short stem (launched in 2015) over a follow-up period of 3 years. According to the study protocol, 100 hip osteoarthritis patients who consecutively received an unilateral cementless calcar-guided short stem (ANA.NOVA proxy) at a single department were prospectively included in this mid-term follow-up study. Thirteen patients were lost to follow-up, resulting in 87 patients with unilateral THA who fulfilled the criteria for migration analysis with EBRA-FCA. The cohort comprised 41 males (mean age: 60 ± 16.5; mean BMI (Body Mass Index): 30 ± 13) and 46 females (mean age: 61 ± 15.5; mean BMI: 27 ± 10). Seven standardized radiographs per patient were analyzed with EBRA-FCA. An average migration of 2.0 mm (0.95-3.35) was observed within the first 3 years. The median increase during the first year was higher than in the second and third year (1.2 mm [IQR: 0.5-2.15] vs. 0.3 mm [IQR: 0.1-0.6 mm] vs. 0.25 mm [IQR: 0.1-0.5 mm]. Detected migration did not lead to stem loosening, instability, dislocation, or revision surgery in any patient. A higher risk for subsidence was observed in male and heavyweight patients, whereas the female gender was associated with a lower risk. No correlation between migration and revision could be observed. Although moderate subsidence was detectable, the performance of the short stem ANA.NOVA proxy is encouraging. Yet, its use may be re-considered in overweight and male patients due to more pronounced subsidence.

Finite element analysis of a hybrid corrugated hip implant for stability and loading during gait phases

Implants used in total hip replacements (THR) exhibit high failure rates and up to a decade of operational life. These surgical failures could be mainly attributed to the improper positioning, post-surgical stability and loading, of the implants during different phases of the gait. Typically, revised surgeries are suggested within a few years of hip implantation, which requires multiple femoral drilling operations to remove an existing implant, and to install a new implant. The pain and trauma associated with such procedures are also challenging with the existing hip implants. In this work, we designed a novel corrugated hip implant with innovative dimensioning as per ASTM standards, and grooves for directed insertion and removal (using a single femoral drilling and positioning operation). Biocompatible titanium alloy (Ti6Al4V) was chosen as the implant material, and the novel implant was placed into a femur model through a virtual surgery to study its stability and loading during a dynamic gait cycle. A detailed mesh convergence study was conducted to select a computationally accurate finite element (FE) mesh. Tight fit and frictional fit attachment conditions were simulated, and the gait induced displacements and stresses on the implant, cortical and cancellous bone sections were characterized. During walking, the implant encountered the maximum von-Mises stress of 254.97 MPa at the femoral head. The analyses indicated low micro-motions (i.e., approximately 7μm) between the femur and implant, low stresses at the implant and bone within elastic limits, and uniform stress distribution, which unlike existing hip implants, would be indispensable for bone growth and implant stability enhancement, and also for reducing implant wear.

A 24-year single-centre experience with Collum Femoris Preserving stem: clinical and radiological results in young and elderly population

OBJECTIVE

The primary aim was to evaluate the long-term follow-up of Collum Femoris Preserving (CFP) stem, specifically focusing on stem survivorship, complications, as well as on clinical and radiological results. The secondary study objective is an age-based sub-analysis (<65 years vs. ⩾65 years) of long-term results.

MATERIALS AND METHODS

We performed a retrospective analysis of patients who underwent CFP implantation between 1997 and 2009. A total of 311 patients (342 hips) were included with a mean follow-up of 15.8 ± 2.2 (range 11-24) years. 2 age groups were analysed: Group-Y (age <65) and Group-E (age ⩾65). Group-Y included 182 hips (mean follow-up 16.3 ± 4.2 years), whereas Group-E included 160 hips (mean follow-up 15.5 ± 3.7 years). Clinical (HHS, OHS and VAS) and radiological data were obtained at final follow-up. Any complications, reoperations, prosthetic components revisions and stem revisions were analysed.

RESULTS

According to HSS score, 95% of patients reported excellent/good results (95.6% Group-Y vs. 94.4% Group-E) with an overall stem survival rate of 93.3% (94% Group-Y vs. 92.5% Group-E; p = 0.37). Overall, 87% of stem revisions were performed with primary stems. The rate of prosthetic components revision was 9.9 % (9.9% in Group-Y vs. 10% in Group-E; p = 1). The reoperation rate was 10.8% (11.5% in Group-Y vs. 10.0% in Group-E; p = 0.73).

CONCLUSIONS

The CFP stem provides good clinical and radiological long-term results with low rate of complications in both young and elderly patients. No significant difference in stem revision and reoperation rates was observed between the 2 groups. Both in elderly and young patients, CFP stem allows revisions to be performed with primary stems.

Do Cementless Short Tapered Stems Reduce the Incidence of Thigh Pain After Hip Arthroplasty? Systematic Review and Meta-Analysis

BACKGROUND

The purpose of this study was to determine whether short tapered stems reduce the rate of thigh pain through a systematic review and meta-analysis of comparative studies between short tapered stems and standard-length tapered stems.

METHODS

We conducted a meta-analysis of comparative studies: 1) retrospective studies and 2) randomized controlled trials (RCTs), on 2 stem designs: short tapered stem versus standard-length tapered stem. Studies were selected by means of the following criteria: 1) study design: retrospective comparative studies, prospective comparative studies, RCTs; 2) study population: patients with total hip arthroplasty or hemiarthroplasty for hip disease or hip fracture; 3) intervention: short tapered stem and standard tapered stem; and 4) outcomes; thigh pain, other clinical results.

RESULTS

Among the 250 articles that were identified at the initial search, 6 studies, 4 RCTs and 2 retrospective comparative studies, were included in this meta-analysis. In the analysis of retrospective studies, the short tapered stem reduced the risk of thigh pain compared to the standard tapered stem (risk ratio [RR] = 0.13; 95% confidence interval [CI], 0.02-0.09; Z = -2.07; P = 0.039). However, in the analysis of RCTs, the incidence of thigh pain was similar between the two stem designs (RR = 1.21; 95% CI, 0.76-1.93; Z = 0.82; P = 0.410). Overall meta-analysis including all studies showed that the short tapered stem did not reduce the incidence of thigh pain compared to the standard-length tapered stem (RR = 0.91; 95% CI, 0.59-1.40; Z = -0.44, P = 0.663).

CONCLUSIONS

We did not find a significant difference in the incidence of thigh pain between short tapered stem and standard tapered stem in hip arthroplasty.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42021231240.

Modular neck stems in total hip arthroplasty: current concepts

Modular neck (MN) implants can restore the anatomy, especially in deformed hips such as sequelae of development dysplasia.

Early designs for MN implants had problems with neck fractures and adverse local tissue, so their use was restricted to limited indications.

Results of the latest generation of MN prostheses seem to demonstrate that these problems have been at least mitigated.

Given the results of the studies presented in this review, surgeons might consider MN total hip arthroplasty (THA) for a narrower patient selection when a complex reconstruction is required.

Long MN THA should be avoided in case of body mass index > 30, and should be used with extreme caution in association with high offset femoral necks with long or extra-long heads. Cr-Co necks should be abandoned, in favour of a titanium alloy connection.

Restoring the correct anatomic femoral offset remains a challenge in THA surgeries.

MN implants have been introduced to try to solve this problem. The MN design allows surgeons to choose the appropriate degree and length of the neck for desired stability and range of motion.

Cite this article: EFORT Open Rev 2021;6:751-758. DOI: 10.1302/2058-5241.6.200064

Calcar-guided short-stem total hip arthroplasty: Will it be the future standard? Review and perspectives

Short stems in total hip arthroplasty (THA) are becoming increasingly popular. In Germany, already 10.4% of all primary THAs are performed using a cementless short stem. The concept of modern, calcar-guided, short stems aims for an individualized reconstruction of the hip anatomy by following the calcar of the femoral neck, a bone- and soft-tissue-sparing implantation technique, and physiological loading. The stem design uses either metaphyseal fixation alone or additional diaphyseal anchoring, depending on the stem alignment and indication. These individualized anchorage types increase the potential indications for the safe use of a short stem. The design features may account for potential advantages of current short stem implants compared with earlier short-stem designs, particularly in cases of reduced bone quality or osteonecrosis of the femoral head and femoral neck fractures. The implantation technique, however, requires distinct knowledge regarding the characteristics of varus and valgus positioning, with the potential for clinical consequences. A learning curve for surgeons new to this technique must be taken into account. Cortical contact with the distal lateral cortex appears to be crucial to provide sufficient primary stability, and the use of intraoperative imaging to identify “undersizing” is highly recommended. Current results of several national registries indicate that calcar-guided short stems are among the most successful implants in terms of mid-term survivorship. However, long-term data remain scarce. This review introduces the characteristics of calcar-guided short-stem THA and summarizes the current evidence.

Cemented short-stem total hip arthroplasty: Characteristics of line-to-line versus undersized cementing techniques using a validated CT-based finite element analysis

Short stems are becoming increasingly popular in total hip arthroplasty as they preserve the bone stock and simplify the implantation process. Short stems are advised mainly for patients with good bone stock. The clinical use of short stems could be enlarged to patients with poor bone stock if a cemented alternative would be available. Therefore, this study aimed to quantify the mechanical performance of a cemented short stem and to compare the "undersized" cementing strategy (stem one size smaller than the rasp) with the "line-to-line" technique (stem and rasp with identical size). A prototype cemented short stem was implanted in eight pairs of human cadaveric femora using the two cementing strategies. Four pairs were experimentally tested in a single-legged stance condition; stiffness, strength, and bone surface displacements were measured. Subject-specific nonlinear finite element models of all the implanted femora were developed, validated against the experimental data, and used to evaluate the behavior of cemented short stems under physiological loading conditions resembling level walking. The two cementing techniques resulted in nonsignificant differences in stiffness and strength. Strength and stiffness as calculated from finite element were 8.7 ± 16% and 9.9 ± 15.0% higher than experimentally measured. Displacements as calculated from finite element analyses corresponded strongly (R ²  ≥ .97) with those measured by digital image correlation. Stresses during level walking were far below the fatigue limit for bone and bone cement. The present study suggests that cemented short stems are a promising solution in osteoporotic bone, and that the line-to-line and undersized cementing techniques provide similar outcomes.

Long-Term Outcomes of 496 Anatomical Cementless Modular Femoral Stems: Eleven to Twenty Years of Follow-Up

BACKGROUND

The aim of the study is to assess the long-term outcomes of this specific stem (anatomical cementless modular stem ESOP), to review the survivorship, complication rate, and radiographic and clinical outcomes.

METHODS

Descriptive and analytical retrospective longitudinal observational study of patients was operated on total hip arthroplasty between 1998 and 2007. Four hundred ninety-six prostheses corresponding to 447 patients were reviewed, mean age was 65.8 years (standard deviation [SD] ±11.6 years), and median follow-up time was 13.4 years (range 1-20). The most used cups were cementless (75.8%). The most frequent friction pairs were metal-polyethylene (53.1%) and ceramic-polyethylene (24.2%). Main variables analyzed were stem survival, subsidence, coronal orientation, osteolysis, reintervention, and Oxford Hip Score.

RESULTS

From 496 implants, there were 22 lost to follow-up (4.4%). Stem revision was performed in 51 patients: 26 periprosthetic joint infections (2-stage revision), 16 periprosthetic fractures, and 8 one-stage revisions (6 real aseptic loosening with negative culture after revision). The stem survivorship at more than 15 years for any reason was 89.2% and for aseptic loosening 97.97%. No specific complications were found due to modularity. The mean subsidence and orientation was 2.06 mm (SD ±5.11 mm) and 0.41° varus (SD ±2.20°) respectively. Subsidence >5 mm or varus >5° was associated with a higher revision rate. Osteolysis was found in 110 patients (zone I = 79, VII = 57), associated with zirconium-polyethylene, without relationship to the stem revision rate or Oxford Hip Score.

CONCLUSION

To our knowledge, this study represents the largest series of this stem, revealing an excellent survival rate and long-term clinical outcomes similar to the best results of classical cementless stems published in the literature.

Primary outcomes of a femoral neck-preserving stem: a multicentre clinical-radiological analysis at 5-year follow-up

PURPOSE

The aim of this prospective study was to evaluate the clinical-radiological outcomes of the Alteon Neck Preserving Stem (ANPS) (Exactech, Gainesville, FL, USA) implanted in four different centres by five senior hip surgeons with a minimum of 5 years of follow-up.

MATERIAL AND METHOD

We conducted a multicentre prospective study that analysed 155 consecutive total hip replacements during 2014. We performed clinical-radiological analysis measuring Harris Hip Score (HHS), subjective satisfaction evaluation, radiolucencies, position of components, limb length discrepancy, heterotopic ossification, medical and surgical complications and a survival analysis at 5 years follow-up.

RESULTS

Thigh pain was reported in 5 cases (3.2%), 2 of which reported mild pain, 2 moderate, and 1 severe. In 2 cases, subsidences of 3 mm were detected in the first scheduled X-ray, both related to intraoperative fractures with no progression after 3 months. The overall complication rate was 5.8% and 6 of the 9 complications were in the first 30 cases. Mean HHS improved from 42.9 points (range 37.2-55.7 points) preoperatively to 94.9 on average (range 87-98) at the end of the follow-up (p <0.01). Subjective evaluation was excellent in 130 (83.87%) cases and good in 25 patients (16.13%).

CONCLUSIONS

The clinical-radiographic results of ANPS THR are satisfactory. The mid-term results are promising. However, long-term follow-up studies are necessary to confirm the validity of the concept.

Comparison of radiographic changes in rectangular curved short stem with thin versus thick porous coating for cementless total hip arthroplasty: a retrospective study with a propensity score matching

Background

Radiographic changes that appear relatively quickly after fixation of cementless stem in total hip arthroplasty (THA) vary depending on the stem design and fixation style. The present study compared radiographic changes between two types of rectangular curved short stems of similar shape.

Methods

This retrospective study included 118 hips that underwent primary cementless THA with an anterolateral supine approach using a rectangular, curved, short stem performed by the same surgeon between June 2015 and June 2019. Among the examined hips, 39 had a thicker porous coating stem (thicker group) and 66 had a thinner porous coating and reduced tip stem (thinner group) and at least 12-month follow-up. Radiographs taken during the final course observation were assessed. Propensity score matching was performed based on demographic data and comparisons were made using pairs of 25 hips each. Statistical analysis was performed using chi-square test and p values ≤ 0.05 indicated statistical significance.

Results

The pattern of the radiolucent lines showed a significant difference after matching (p = 0.0044). A “proximal and distal” pattern was most common in the thicker group and a “distal only” pattern was most common in the thinner group. There was notable and significant difference in cortical hypertrophy in the thicker group after matching (p = 0.024).

Conclusions

Although the two short stems were similar shapes, the short-term radiographic changes were different. The thinner group showed fewer radiographic changes than the thicker group, making it a more “silent” stem.

Alendronate enhances osseointegration in a murine implant model

Administration of bisphosphonates following total joint arthroplasty might be beneficial to reduce aseptic loosening. However, their effects on peri-implant bone formation and bone-implant interface strength have not been investigated yet. We used a physiologically loaded mouse implant model to investigate the short-term effects of postoperative systemic alendronate on osseointegration. A titanium implant with a rough surface was inserted in the proximal tibiae of 17-week-old female C57BL/6 mice (n = 44). Postimplantation mice were given alendronate (73 μg/kg/days, n = 22) or vehicle (n = 22) 5 days/week. At 7- and 14-day postimplantation, histology and histomorphometry were conducted. At 28 days, microcomputed tomography and biomechanical testing were performed (n = 10/group). Postoperative alendronate treatment enhanced osseointegration, increasing maximum pullout load by 45% (p < .001) from 19.1 ± 4.5 N in the control mice to 27.6 ± 4.9 N in the treated mice, at day 28 postimplantation. Alendronate treatment increased the bone volume fraction by 139% (p < .001) in the region distal to the implant and 60% (p < .05) in the peri-implant region. At 14-day postimplantation, alendronate treatment decreased the number of osteoclasts per bone perimeter (p < .05) and increased bone volume fraction (p < .01) when compared with the control group. Postimplantation, short-term alendronate treatment enhanced osseointegration as demonstrated by increased bone mass, trabecular bone thickness, and maximum pullout load. Alendronate decreased peri-implant osteoclasts while preserving peri-implant osteoblasts and endothelial cells, in turn, increasing bone volume fraction. This data supports the postoperative clinical use of bisphosphonates, especially in patients with high risks of aseptic loosening.

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.

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis

Background

The objective is to compare, by the means of finite elements analysis, the biomechanical behavior of a conventional stem of proven performance with a short stem based on the same fixation principles.

Methods

A 3D femur was modeled from CT scan data, and real bone density measures were incorporated into it. Load stresses were applied to that bone in 3 different scenarios: without prosthesis, with the conventional stem, and with the short stem. Different bone loading patterns were compared by Gruen’s zones both visually and statistically using Welch’s test.

Results

The implantation of a stem generates a certain degree of stress shielding in the surrounding bone, but the pattern of the change is very similar in the compared stem models. Although there is statistical significance (P < 0.01) in the mean stress variation in most of the Gruen’s zones, the magnitude of the difference is always under 2 MPa (range: 0.01 – 1.74 MPa).

Conclusions

The bone loading patterns of the traditional stem and the short stem are very similar. Although there is no evidence of a link between biomechanics and clinical outcomes, our results may suggest that theoretical advantages of short stems can be exploited without the fear of altering bone loading patterns.

The clinical outcome of the Metha short hip stem: a systematic scoping review

INTRODUCTION

Short femoral stems were designed to bridge the gap between conventional straight design stems and hip resurfacing prostheses in total hip arthroplasty (THA). A number of clinical trials have been recently conducted to assess the clinical and safety profile of the cementless, colarless, tapered Metha short hip stem in young or active middle-aged individuals.

METHODS

A systematic scoping review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. 4 reviewers independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms "short" AND "hip" AND "stem".

RESULTS

From the initial 773 studies we finally chose 12 studies after applying our inclusion-exclusion criteria. The number of operated hips that were included in these studies was 5048 (mean BMI range: 22.7-35.2, mean age range: 44.4-60.4 years, mean follow-up range: 2-9 years). The mean modified Coleman methodology score was 52.3/100, while it ranged from 31/100 to 63/100. All mean clinical outcome scores that were used in the studies illustrated significant postoperative improvement when compared with the respective initial values. The revision rate of the Metha stem for component-related reasons was 2.5%, while the rate of major complications not requiring revision of the Metha stem was 2.8%.

CONCLUSIONS

The Metha stem performs well in young or active middle-aged THA patients. Further studies are required for the assessment of the long-term results.

Robotics in total hip arthroplasty: a review of the evolution, application and evidence base

Robotic systems used in orthopaedics have evolved from active systems to semi-active systems.

Early active systems were associated with significant technical and surgical complications, which limited their clinical use.

The new semi-active system Mako has demonstrated promise in overcoming these limitations, with positive early outcomes.

There remains a paucity of data regarding long-term outcomes associated with newer systems such as Mako and TSolution One, which will be important in assessing the applicability of these systems.

Given the already high satisfaction rate of manual THA, further high-quality comparative studies are required utilizing outcome scores that are not limited by high ceiling effects to assess whether robotic systems justify their additional expense.

Cite this article: EFORT Open Rev 2020;5:866-873. DOI: 10.1302/2058-5241.5.200037

Mid-term results of 119 Taperloc Microplasty™ femoral stems after a mean 61 months (50-82) of follow-up

INTRODUCTION

Short stems are not all the same and do not meet the same objectives in terms of shape, fixation and biomechanics. The Taperloc Microplasty™ is a shortened stem. In France, no articles have been published on this subject and very few articles are available in the international literature. We therefore decided to analyse results for this stem after a mean follow-up of 61 months, asking the following questions: (1) Is the survival of the Taperloc Microplasty™ at least equivalent to the best conventional cementless prostheses on the market, i.e. with a 10-year revision rate of less than 5% according to NICE criteria? (2) Have the expected benefits of short stems been confirmed?

HYPOTHESIS

The Taperloc Microplasty™ prosthesis meets the NICE criteria with a revision rate of less than 5% at 10 years.

MATERIALS AND METHODS

This is a retrospective single-surgeon study of 119 prostheses implanted between April 2013 and December 2015. The inclusion criteria were hip arthrosis or avascular necrosis of the femoral head in patients under the age of 70 regardless of height or weight, excluding Dorr type C femurs. The series consisted of 108 patients (11 bilateral total hip arthroplasties (THA)) with a mean age of 58.8±10 years [17-70]; 81 were men and 38 were women.

RESULTS

The results were assessed in 110 hips (103 patients since 9 hips (7 patients) were lost to follow-up) at a mean follow-up of 61±8 months [50-82]. At follow-up the Postel-Merle d'Aubigné (PMA) score was 17.8±0.8 [12-18] and the Oxford score 13.1±3.5 [12-41] (p<0.05 versus pre operative). On X-rays, we identified 9 pedestal signs (7.5%) below the distal end of the stem, 6 calcar atrophies (5%), but no cortical hypertrophy greater than 2 mm, no stem subsidence greater than 5mm, and no radiolucent line indicating the absence of integration. The survivorship at 61 months was 100% (95% CI: 0.905; 1.095), taking femoral revision as the end-point and 98.2% (95% CI: 0.887; 1.077) considering revision for any reason.

CONCLUSION

The Taperloc Microplasty™ stem is equivalent to the best conventional cementless prostheses on the market in selected surgical indications after a mean follow-up of 61 months. The follow-up is still not sufficient to confirm all the benefits expected from this type of implant.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Mid-term migration pattern of a calcar-guided short stem: A five-year EBRA-FCA-study

BACKGROUND

Short-term results of several short-stem designs have indicated early axial migration. Mid- and long-term results for most designs are lacking. The objective of this study was to evaluate the mid-term migration pattern of a calcar-guided short stem five years postoperative.

METHODS

Implant migration of 191 calcar-guided short stems was assessed by Ein-Bild-Roentgen-Analysis Femoral-Component- Analysis (EBRA-FCA) 5 years after surgery. Migration pattern of the whole group was analyzed and compared to the migration pattern of implants potentially being "at hazard" with a subsidence of more than 1.5 mm at 2 years postoperatively. Influence of preoperative Dorr types (A vs. B vs. C), age (<70 vs. >70 years), gender (female vs. male), weight (<90 kg vs. >90 kg), BMI (<30 vs. >30) and uni-vs. bilateral procedures on mid-term migration pattern was analyzed. Additionally outcome of varus- and valgus stem alignment was assessed.

RESULTS

Mean axial subsidence was 1.5 mm (SD 1.48 mm) at final follow-up. Two years after surgery 73 short stems were classified "at hazard". Of these stems, 69 cases showed secondary stabilisation in the following period, whereas 4 cases presented unstable with more than 1 mm of further subsidence. Stem revision was not required neither in the group of implants with early stabilisation nor the group with pronounced early onset migration. Male gender and heavy-weight patients had a significant higher risk for axial migration, as well as extensive valgus stem alignment, whereas for Dorr type B, compared to A, no statistical difference could be observed.

CONCLUSIONS

In most cases, even in the group of stems being "at hazard", settling could be documented. While different Dorr types did not show a statistically significant impact on axial migration, particularly in male and heavy-weight patients the risk of continuous subsidence is increased. In those 4 cases with further migration, undersizing of the stem could be recognized. At present, clinical consequences are still uncertain.

Blood loss in primary total hip arthroplasty with a short versus conventional cementless stem: a retrospective cohort study

INTRODUCTION

To evaluate the impact of short cementless stem on several clinical and radiographic outcomes, with particular focus on blood loss, in comparison with conventional cementless stem in total hip arthroplasty (THA).

MATERIALS AND METHODS

Patients undergoing THA with GTS short stem or CLS conventional stem were included. Clinical data were retrospectively collected including preoperative and postoperative day 1 value for haemoglobin (HB); rate of postoperative blood transfusions; intraoperative bone infractions; stem alignment; 5-year follow-up Harris Hip Score (HHS) and rate of stem revision at 5 years of follow-up of the short and conventional cementless stem.

RESULTS

GTS and CLS stem group included 374 and 321 patients, respectively. The mean difference between the preoperative and postoperative day 1 HB value was 3.98 g/dL (SD 1.12) and 3.67 g/dL (SD 1.19) in the GTS and CLS group, respectively, which correspond to a crude effect (β) of 0.32 (95% CI 0.15; 0.49) and adjusted effect of 0.11 (95% CI - 0.08; 0.3). GTS group reported a significantly higher number of patients with excellent results in terms of HHS (p = 0.001). The rate of intraoperative bone infractions was 1.6% and 0.3% in the GTS and CLS group, respectively (p = 0.013). At radiographic assessment, the rate of varus position of the stem was 14% in the GTS group and 6% in the CLS group (p < 0.0001). The rate of stem revision at 5 years of follow-up was 0.8% and 0.4% in the GTS and CLS group, respectively (p = 0.63).

CONCLUSIONS

GTS short stem was not associated with a clinically significant lower blood loss in the immediately postoperative period. Unadjusted exploratory analyses show that GTS stem provides the same results of CLS stem in terms of HHS and rate of stem revision at 5 years of follow-up.

A comparison of patient-reported outcome measures (PROMs) between short and conventional stem hip replacements: a systematic review and meta-analysis

INTRODUCTION

Short stem hip replacements may allow preservation of proximal bone stock and minimise soft tissue disruption, easing future revision surgery. However patient satisfaction with these implants must be determined before widespread use. We aimed to compare patient reported outcome measures (PROMs) between short and conventional stem hip replacements.

METHODS

A systematic review was conducted according to PRISMA guidelines for studies comparing short and conventional stem hip replacements with validated PROMs. Meta-analyses were performed for studies reporting Harris Hip and WOMAC scores. Study bias was assessed with the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale.

RESULTS

24 studies, incorporating 2593 total hip replacements were included for qualitative analysis. 17 studies were included in the meta-analyses. Of the 7 excluded, 1 study reported the Japanese Orthopaedic Association score and 2 others reported the Oxford Hip score. All three showed no difference between the stems. A meta-analysis of 17 studies reporting Harris hip scores showed no statistically significant difference between short and conventional stems (standard mean difference (SMD) -0.06, 95% CI -0.20-0.07, p = 0.35). 6 studies reported WOMAC scores with higher scores indicating worse outcome. No difference was seen between the two groups (SMD 0.21, 95%CI, -0.01-0.42, p = 0.06). 4 studies reported higher WOMAC scores as better. Once again, a meta-analysis showed no statistically significant difference between the stems (SMD 0.28, 95% CI -0.07-0.63, p = 0.12).

CONCLUSIONS

Our systematic review showed no difference in PROMs between short and conventional stem total hip replacements. This is in keeping with previous evidence but is a more comprehensive analysis. Short stems may have an important role in younger individuals as they allow preservation of proximal femoral bone, minimal access surgery and are amenable to abnormal anatomy. The current literature is hindered by non-uniform methodologies and outcome assessments across studies. Further, standardised, high quality evidence is required before widespread changes in practice.

Short-Stem Prostheses in Total Hip Arthroplasty: An Unexpected Short-Term Complication: A Report of 2 Cases

CASE

We present here 2 cases of postoperative stress fractures in the setting of a short-stem implant. Both patients had well-aligned implants with good bone quality and presented with delayed onset and atraumatic thigh pain. They were diagnosed with periprosthetic fractures around stable implants.

CONCLUSIONS

We now reserve the use of these stems for patients who have femoral morphology and are unable to accept standard stems. Patients who complain of new-onset thigh pain in the setting of short-stem total hip arthroplasty should have a femoral stress fracture included in the differential diagnosis and be worked up appropriately.

Outcome of short- to medium-term migration analysis of a cementless short stem total hip arthroplasty using EBRA-FCA: a radiological and clinical study

INTRODUCTION

Stress shielding may lead to aseptic loosening which is a common reason for implant failure. An established method to identify implants with risk of implant failure caused by aseptic loosening is to measure early migration of the stem with the "Ein Bild Roentgen Analyse" femoral component analysis (EBRA-FCA). Therefore, the aim of this study was to measure the migration of a cementless short stem prosthesis via EBRA-FCA to predict the future performance.

MATERIALS AND METHODS

A total collective of 71 patients were treated with a cementless short hip stem prosthesis. Indications for surgery were primary coxarthrosis, dysplasia coxarthrosis or femoral head necrosis. After surgery, the patients were followed-up immediately after 3, 6, 12, 24, 36, and 48 months and X-ray images for EBRA-FCA measurements were taken. Axial caudal migration as well as the varus/valgus tilting of the prosthesis was determined. Possible influencing factors like BMI, age, diagnosis, gender or Harris Hip Score (HHS) on the migration of the stem were assessed.

RESULTS

HHS increased significantly direct postoperatively (p < 0.001). At the second follow-up the average caudal migration was 0.42 ± 0.52 mm (range: 0.00-2.85 mm) (p < 0.001). A total of 14 patients underwent a caudal migration greater than 1.5 mm until 48 months. The initial varus and valgus tilts within the first 3 months were significant (p < 0.001). No correlations between BMI, age, diagnosis, gender or HHS and the migration as well as the tilting of the cementless short hip stem prosthesis were found.

CONCLUSIONS

Although initial axial caudal migration as well as tilting tendencies in varus or valgus position can be detected, there is no marked migration of the examined prosthesis after the first 48 months. Likewise, no aseptic early loosening was detected throughout the study period, which indicates good osseointegration of the short stem prosthesis.

Migration analysis of a metaphyseal-anchored short femoral stem in cementless THA and factors affecting the stem subsidence

Background

Early femoral stem subsidence following a cementless THA is correlated with aseptic loosening of the femoral component. The short femoral stems allow bone sparing and implantation through a minimally invasive approach; however, due to their metaphyseal anchoring, they might demonstrate different subsidence pattern than the conventional stems.

Methods

In this prospective single-center study, a total of 68 consecutive patients with an average age of 63 years, and a minimum follow-up of 5 years following a cementless THA with a metaphyseal-anchored short femoral stem were included. The femoral stem subsidence was evaluated using “Ein Bild Roentgen Analyse” (EBRA).

Results

Average stem migration was 0.96 +/− 0.76 mm at 3 months, 1.71 +/− 1.26 mm at 24 months, and 2.04+/− 1.42 mm at last follow-up 60 months postoperative. The only factor that affected migration was a stem size of 6 or more (r² = 5.74; p = 0.039). Subdivision analysis revealed, that only in females migration appeared to be affected by stem size irrespective of weight but not in men (female stem size of 6 or more vs. less (Difference = − 1.48 mm, R² = 37.5; p = 0.001). Migration did not have an impact on clinical outcome measures.

Conclusions

The examined metaphyseal-anchored short femoral stem showed the highest subsidence within the first 3 months postoperative, the implant began to stabilize at about 24 months but continued to slowly migrate with average total subsidence of 2.04 mm at 5 years following the THA. The amount of stem subsidence was not associated with worse clinical outcomes such as HHS, patient satisfaction, or pain.

Trends in Total Hip Arthroplasty in Germany from 2007 to 2016: What Has Changed and Where Are We Now?

BACKGROUND

The number of total hip arthroplasties (THA) is rising in many industrialized nations. At the same time, the evidence regarding different types of prostheses and fixation techniques is constantly evolving. Therefore, this study aimed to analyze changes in THA by these advancements during the last decade.

METHODS

A retrospective analysis of data provided by the Federal Statistical Office of Germany from 2007 to 2016 was conducted using codes from the German procedure classification system and associated International Statistical Classification of Diseases and Related Health Problems codes. THA procedures were evaluated according to diagnoses, sex, and age of patients, along with the distribution of different prosthesis types. Additionally, changes in these parameters over time were analyzed.

RESULTS

From 2007 to 2016 a total of 2 157 041 primary THA procedures were performed in Germany, with an increase of 14.4% over this period. Overall, cementless standard THA (STHA) was used most frequently (50.0%), followed by hybrid variants (18.8%), hemiarthroplasties (15.9%), cemented standard THA (cSTHA; 9.2%), cementless short-stem THA (ssTHA; 4.8%), and hip resurfacing (HR; 0.9%) techniques. During the study period, the number of cSTHA and HR decreased significantly, whereas the use of STHA and ssTHA rose substantially, with a significantly higher application of these procedures in the elderly population. While osteoarthritis of the hip joint was the main indication for THA, several procedure-specific differences were identified.

CONCLUSION

The present data clearly demonstrate an increase in the use of cementless fixation for THA in Germany during the last decade and document a rise in ssTHA in recent years with, in contrast, the use of HR decreasing to a minimum.

Short stems have lower load at failure than double-wedged stems in a cadaveric cementless fracture model

Objectives

Periprosthetic femoral fractures (PFFs) have a higher incidence with cementless stems. The highest incidence among various cementless stem types was observed with double-wedged stems. Short stems have been introduced as a bone-preserving alternative with a higher incidence of PFF in some studies. The purpose of this study was a direct load-to-failure comparison of a double-wedged cementless stem and a short cementless stem in a cadaveric fracture model.

Methods

Eight hips from four human cadaveric specimens (age mean 76 years (60 to 89)) and eight fourth-generation composite femurs were used. None of the cadaveric specimens had compromised quality (mean T value 0.4 (-1.0 to 5.7)). Each specimen from a pair randomly received either a double-wedged stem or a short stem. A materials testing machine was used for lateral load-to-failure test of up to a maximal load of 5000 N.

Results

Mean load at failure of the double-wedged stem was 2540 N (1845 to 2995) and 1867 N (1135 to 2345) for the short stem (p < 0.001). All specimens showed the same fracture pattern, consistent with a Vancouver B2 fracture. The double-wedged stem was able to sustain a higher load than its short-stemmed counterpart in all cases. Failure force was not correlated to the bone mineral density (p = 0.718).

Conclusion

Short stems have a significantly lower primary load at failure compared with double-wedged stems in both cadaveric and composite specimens. Surgeons should consider this biomechanical property when deciding on the use of short femoral stem.

Cite this article: A. Klasan, M. Bäumlein, P. Dworschak, C. Bliemel, T. Neri, M. D. Schofer, T. J. Heyse. Short stems have lower load at failure than double-wedged stems in a cadaveric cementless fracture model. Bone Joint Res 2019;8:489–494. DOI: 10.1302/2046-3758.810.BJR-2019-0051.R1.

One-staged combined hip and knee arthroplasty: retrospective comparative study at mid-term follow-up

Background

To date, few knowledge is available about safety and effectiveness of one-staged combined hip and knee arthroplasty. The aim of our study was to evaluate, in a comparative fashion, complications and outcomes in patients who underwent one-staged hip and knee arthroplasty.

Methods

Forty-two patients were enrolled and allocated into two groups of 21 patients each: one-staged hip and knee arthroplasty (group A) and two-staged hip and knee arthroplasty (group B). The follow-up averaged 50.2 months. Postoperative complications and implant survivorship were assessed prospectively. Outcomes were evaluated with Harris Hip score (HSS), Western Ontario Mc-Ministry score for the hip (h-WOMAC), Knee Society score (KSS), and Western Ontario Mc-Ministry knee score (k-WOMAC). Hip and knee range of motion (ROM) were measured both preoperatively and at the last follow-up.

Results

Two (9.5%) patients in group A and three (14.3%) patients in group B developed complications (P = 0.8). Although a significant decrease in postoperative haemoglobin (Hgb) values was found in group A patients during the hospital stay, no differences in blood transfusions were found (P = 0.8). No significant differences were found comparing clinical-functional outcomes between the two groups, while a significant reduction of hospital length of stay was shown in group A patients.

Conclusions

One-staged combined hip and knee arthroplasty could be considered in patients with co-existing severe hip and knee osteoarthritis, providing similar complications and mid-term outcomes of two-staged procedures. However, the reproducibility safety and reliability of these procedures should be confirmed in prospective comparative randomised trials with more numerous patients.

Trial registration

Retrospectively registered

Clinical relevance of bone remodelling around conventional and conservative (short-stem) total hip arthroplasty implants

Based on data from the existing literature, we can safely suggest that bone mineral changes around cementless and cemented conventional femoral stems, and conservative femoral stems, are not predictive of either satisfactory or unsatisfactory total hip arthroplasty long term clinical outcomes. Additionally, studies with a follow up shorter than 5-10 years are perhaps clinically irrelevant. These observations may be helpful in interpreting the existing literature.

Hip replacement

Total hip replacement is a frequently done and highly successful surgical intervention. The procedure is undertaken to relieve pain and improve function in individuals with advanced arthritis of the hip joint. Symptomatic osteoarthritis is the most common indication for surgery. In paper 1 of this Series, we focus on how patient factors should inform the surgical decision-making process. Substantial demands are placed upon modern implants, because patients expect to remain active for longer. We discuss the advances made in implant performance and the developments in perioperative practice that have reduced complications. Assessment of surgery outcomes should include patient-reported outcome measures and implant survival rates that are based on data from joint replacement registries. The high-profile failure of some widely used metal-on-metal prostheses has shown the shortcomings of the existing regulatory framework. We consider how proposed changes to the regulatory framework could influence safety.