Objective. This study compared the primary stability of two commercially available acetabular components from the same manufacturer, which differ only in geometry; a hemispherical and a peripherally enhanced design (peripheral self-locking (PSL)). The objective was to determine whether altered geometry resulted in better primary stability. Methods. Acetabular components were seated with 0.8 mm to 2 mm interference fits in reamed polyethylene bone substrate of two different densities (0.22 g/cm. 3. and 0.45 g/cm. 3. ). The primary stability of each component design was investigated by measuring the peak failure load during uniaxial pull-out and tangential lever-out tests. Results. There was no statistically significant difference in seating force (p = 0.104) or primary stability (pull-out p = 0.171, lever-out p = 0.087) of the two components in the low-density substrate. Similarly, in the high-density substrate, there was no statistically significant difference in the peak pull-out force (p = 0.154) or lever-out moment (p = 0.574) between the designs. However, the PSL component required a significantly higher seating force than the hemispherical cup in the high-density bone analogue (p = 0.006). Conclusions. Higher seating forces associated with the PSL design may result in inadequate seating and increased risk of component malpositioning or acetabular fracture in the intra-operative setting in high-density bone stock. Our results, if translated clinically, suggest that a purely hemispherical geometry may have an advantage over a peripherally enhanced geometry in high density bone stock. Cite this article: Bone Joint Res 2013;2:264–9

Aims. The aim of this study was to determine if uncemented acetabular polyethylene (PE) liner geometry, and lip size, influenced the risk of revision for instability or loosening. Methods. A total of 202,511 primary total hip arthroplasties (THAs) with uncemented acetabular components were identified from the National Joint Registry (NJR) dataset between 2003 and 2017. The effect of liner geometry on the risk of revision for instability or loosening was investigated using competing risk regression analyses adjusting for age, sex, American Society of Anesthesiologists grade, indication, side, institution type, surgeon grade, surgical approach, head size, and polyethylene crosslinking. Stratified analyses by surgical approach were performed, including pairwise comparisons of liner geometries. Results. The distribution of liner geometries were neutral (39.4%; 79,822), 10° (34.5%; 69,894), 15° (21.6%; 43,722), offset reorientating (2.8%; 5705), offset neutral (0.9%; 1,767), and 20° (0.8%; 1,601). There were 690 (0.34%) revisions for instability. Compared to neutral liners, the adjusted subhazard ratios of revision for instability were: 10°, 0.64 (p < 0.001); 15°, 0.48 (p < 0.001); and offset reorientating, 1.6 (p = 0.010). No association was found with other geometries. 10° and 15° liners had a time-dependent lower risk of revision for instability within the first 1.2 years. In posterior approaches, 10° and 15° liners had a lower risk of revision for instability, with no significant difference between them. The protective effect of lipped over neutral liners was not observed in laterally approached THAs. There were 604 (0.3%) revisions for loosening, but no association between liner geometry and revision for loosening was found. Conclusion. This registry-based study confirms a lower risk of revision for instability in posterior approach THAs with 10° or 15° lipped liners compared to neutral liners, but no significant difference between these lip sizes. A higher revision risk is seen with offset reorientating liners. The benefit of lipped geometries against revision for instability was not seen in laterally approached THAs. Liner geometry does not seem to influence the risk of revision for loosening. Cite this article: Bone Joint J 2021;103-B(12):1774–1782

Aims. To determine if primary cemented acetabular component geometry (long posterior wall (LPW), hooded, or offset reorientating) influences the risk of revision total hip arthroplasty (THA) for instability or loosening. Methods. The National Joint Registry (NJR) dataset was analyzed for primary THAs performed between 2003 and 2017. A cohort of 224,874 cemented acetabular components were included. The effect of acetabular component geometry on the risk of revision for instability or for loosening was investigated using log-binomial regression adjusting for age, sex, American Society of Anesthesiologists grade, indication, side, institution type, operating surgeon grade, surgical approach, polyethylene crosslinking, and prosthetic head size. A competing risk survival analysis was performed with the competing risks being revision for other indications or death. Results. The distribution of acetabular component geometries was: LPW 81.2%; hooded 18.7%; and offset reorientating 0.1%. There were 3,313 (1.5%) revision THAs performed, of which 815 (0.4%) were for instability and 838 (0.4%) were for loosening. Compared to the LPW group, the adjusted subhazard ratio of revision for instability in the hooded group was 2.31 (p < 0.001) and 4.12 (p = 0.047) in the offset reorientating group. Likewise, the subhazard ratio of revision for loosening was 2.65 (p < 0.001) in the hooded group and 13.61 (p < 0.001) in the offset reorientating group. A time-varying subhazard ratio of revision for instability (hooded vs LPW) was found, being greatest within the first three months. Conclusion. This registry-based study confirms a significantly higher risk of revision after cemented THA for instability and for loosening when a hooded or offset reorientating acetabular component is used, compared to a LPW component. Further research is required to clarify if certain patients benefit from the use of hooded or offset reorientating components, but we recommend caution when using such components in routine clinical practice. Cite this article: Bone Joint J 2021;103-B(11):1669–1677

Aims. In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement. Methods. Total hip arthroplasty (THA) motion while standing and sitting was simulated using a MATLAB model (one stem with a cylindrical neck and one stem with a rectangular neck). The primary predictor was the geometry of the neck (cylindrical vs rectangular) and the main outcome was the shape of ROM based on the prosthetic impingement between the neck and the liner. The secondary outcome was the difference in the ROM provided by each neck geometry and the effect of the pelvic tilt on this ROM. Multiple regression was used to analyze the data. Results. The stem with a rectangular neck has increased internal and external rotation with a quatrefoil cross-section compared to a cone in a cylindrical neck. Modification of the cup orientation and pelvic tilt affected the direction of projection of the cone or quatrefoil shape. The mean increase in internal rotation with a rectangular neck was 3.4° (0° to 7.9°; p < 0.001); for external rotation, it was 2.8° (0.5° to 7.8°; p < 0.001). Conclusion. Our study shows the importance of attention to femoral implant design for the assessment of prosthetic impingement. Any universal mathematical model or computer simulation that ignores each stem’s unique neck geometry will provide inaccurate predictions of prosthetic impingement. Cite this article: Bone Joint Res 2021;10(12):780–789

Cemented acetabular components commonly have a long posterior wall (LPW). Alternative components have a hooded or offset reorientating geometry, theoretically to reduce the risk of THR instability. We aimed to determine if cemented acetabular component geometry influences the risk of revision surgery for instability or loosening. The National Joint Registry for England, Wales and Northern Ireland (NJR) dataset was analysed for primary THAs performed between 2003 – 2017. A cohort of 224,874 cemented acetabular components were identified. The effect of acetabular component geometry on the risk of revision for instability or for loosening was investigated using binomial regression adjusting for age, gender, ASA grade, diagnosis, side, institution type, operating surgeon grade, surgical approach, polyethylene crosslinking and head size. A competing risk survival analysis was performed with the competing risks being revision for other indications or death. Among the cohort of subjects included, the distribution of acetabular component geometries was: LPW – 81.2%, hooded – 18.7% and offset reorientating – 0.1%. There were 3,313 (1.47%) revision THAs performed, of which 815 (0.36%) were for instability and 838 (0.37%) were for loosening. Compared to the LPW group, the adjusted subhazard ratio of revision for instability in the hooded group was 2.29 (p<0.001) and 4.12 (p=0.047) in the offset reorientating group. Likewise, the subhazard ratio of revision for loosening was 2.43 (p<0.001) in the hooded group and 11.47 (p<0.001) in the offset reorientating group. A time-varying subhazard ratio of revision for instability (hooded vs LPW) was found, being greatest within the first 6 months. This Registry based study confirms a significantly higher risk of revision THA for instability and for loosening when a cemented hooded or offset reorientating acetabular component is used, compared to an LPW component. Further research is required to clarify if certain patients benefit from the use of hooded or offset reorientating components, but we recommend caution when using such components in routine clinical practice

The protective effect of lipped polyethylene uncemented acetabular liners against revision THA for instability has been reported. However, the effect of lip size has not been explored, nor has the effect on revision THA for loosening. We aimed to determine if uncemented acetabular liner geometry, and lip size, influences the risk of revision THA for instability or loosening. 202511 primary THAs with uncemented polyethylene acetabular components were identified from the NJR dataset (2003 – 2017). The effect of acetabular liner geometry and lip size on the risk of revision THA for instability or loosening was investigated using binomial regression and competing risks survival analyses (competing risks were revision for other causes or death) adjusting for age, gender, ASA grade, diagnosis, side, institution type, surgeon grade, surgical approach, head size and polyethylene crosslinking. The distribution of acetabular liners was: neutral – 39.4%, offset neutral – 0.9%, 10-degree – 34.5%, 15-degree – 21.6%, 20-degree – 0.8%, offset reorientating – 2.82%. There were 690 (0.34%) revision THAs for instability and 604 (0.3%) for loosening. Significant subhazard risk ratios were found in revision THA for instability with 10-degree (0.63), 15-degree (0.48) and offset reorientating (1.6) liners, compared to neutral liners. There was no association found between liner geometry and risk of revision THA for loosening. This Registry based study confirms a significantly lower risk of revision THA for instability when a lipped liner is used, compared to neutral liners, and a higher risk with the use of offset reorientating liners. Furthermore, 15degree liners seem to have a lower risk than 10degree liners. We did not find an association between acetabular liner geometry and revision THA for loosening. 10- and 15-degree lipped polyethylene liners seem to offer a lower revision risk over neutral liners, at least at medium term followup. Further studies are required to confirm if this benefit continues into the long-term

Polished, tapered stems are now widely used for cemented total hip replacement and many such designs have been introduced. However, a change in stem geometry may have a profound influence on stability. Stems with a wide, rectangular proximal section may be more stable than those which are narrower proximally. We examined the influence of proximal geometry on stability by comparing the two-year migration of the Exeter stem with a more recent design, the CPS-Plus, which has a wider shoulder and a more rectangular cross-section. The hypothesis was that these design features would increase rotational stability. Both stems subsided approximately 1 mm relative to the femur during the first two years after implantation. The Exeter stem was found to rotate into valgus (mean 0.2°, . sd. 0.42°) and internally rotate (mean 1.28°, . sd. 0.99°). The CPS-Plus showed no significant valgus rotation (mean 0.2°, . sd. 0.42°) or internal rotation (mean −0.03°, . sd. 0.75°). A wider, more rectangular cross-section improves rotational stability and may have a better long-term outcome

This study aimed to assess the effect of flexion and external rotation on measurement of femoral offset (FO), greater trochanter to femoral head centre (GT-FHC) distance, and neck shaft angle (NSA). Three-dimensional femoral shapes (n=100) were generated by statistical shape modelling from 47 CT-segmented right femora. Combined rotations in the range of 0–50° external and 0–50° flexion (in 10° increments) were applied to each femur after they were neutralised (defined as neck and proximal shaft axis parallel with detector plane). Each shape was projected to create 2D images representing radiographs of the proximal femora.

As already known, external rotation resulted in a significant error in measuring FO but flexion alone had no impact. Individually, neither flexion nor external rotation had any impact on GT-FHC but, for example, 30° of flexion combined with 50°of external rotation resulted in an 18.6mm change in height. NSA averaged 125° in neutral with external rotation resulting in a moderate increase and flexion on its own a moderate decrease. However, 50° degrees of both produced an almost 30 degree increase in NSA.

In conclusion, although the relationship between external rotation and FO is appreciated, the impact of flexion with external rotation is not. This combination results in apparent reduced FO, a high femoral head centre and an increased NSA. Femoral components with NSAs of 130° or 135° may historically have been based on X-ray misinterpretation. This work demonstrates that 2D to 3D reconstruction of the proximal femur in pre-op planning is a challenge.

When inserting a femoral stem, surgeons make use of many visual and tactile cues to be sure that the implant is correctly sized and well-seated. One such cue is the change of pitch that can be heard when the final femoral broach is inserted. This is known to be important, but has not been widely studied.

We set out to analyse the sounds produced during femoral broaching and implant fixation, and to discover whether the absence of these sounds could predict a poor fixation.

We recorded the sound of femoral broaching and definitive implant insertion, for twenty un-cemented Corail total hip replacements. Procedures were performed by the same surgeon, in the same theatre. The recordings were visualised using audio editing software, and a Fast Fourier Transform was used to identify the dominant audio frequencies.

In 19 of the 20 cases, the final strikes of the final femoral broach displayed a distinctive pattern, with the most prominent frequencies being harmonics (multiples of a fundamental frequency) which had a wavelength directly related to the length of the femoral canal. This contrasts with initial strikes, where multiple unrelated frequencies were present.

Postoperative radiographs were examined by two surgeons independently, to assess implant sizing and positioning. The one case, in which the harmonic pattern was not observed, was found on radiographs to be an undersized, varus malpositioned implant.

We demonstrate that a characteristic frequency pattern is present when impacting cancellous bone with a well-sized and well-placed femoral broach. When the pattern was absent, the broach and implant were undersized and malpositioned. We hypothesise that this pattern arises when broach and femur are vibrating as one, indicating adequate contact with, and compression of, cancellous bone.

Cementless distally locked stems were introduced in revision hip arthroplasty (RTHA) in the late 1980s to deal with severe femoral bone loss. These implants have not been assessed over the long-term, particularly the influence of the design and porous coating. Therefore we performed a retrospective case-control study at a minimum 10-years' follow-up comparing the straight Ultime™ stem with 1/3 porous coating versus the anatomical Linea™ stem with 2/3 proximal coating with hydroxyapatite.

We performed a single-center case-control study measuring survival, function based the Harris and Oxford-12 scores, and rate of thigh pain. X-rays were done at regular intervals and at follow-up. No femoral bone graft was used at insertion.

The two groups were comparable in terms of age, sex and follow-up (mean 12.2 years in Ultime and 10.8 years in Linea cohorts); however they differed in the severity of bone loss therefore the results were adjusted according to this variable. Ten-year survival considering revision for any reason was 63.5% ± 5.4 for Ultime and 91.6% ± 2.7 for Linea (p < 0.001). Merle d'Aubigné scores and Oxford-12 were higher in the Linea group 82.9 ± 12.4 and 26.3/48, respectively, versus 69.5 ± 16 and 21/48 in the Ultime group (p < 0.001). Thigh pain was observed in 30% of Ultime cases versus 3% of Linea cases. Bone reconstruction measured via cortical thickness was better in the Linea group and correlated to metaphyseal filling at insertion.

This study confirms the benefits of using of locked stems in RTHA with severe bone loss. Better metaphyseal filling and optimized porous coating help to minimize thigh pain and the revision rate.

Periprosthetic femoral fractures (PFFs) remain a major concern following cementless total hip arthroplasty (THA). This study aimed to evaluate the association between different types of cementless tapered stems and the risk of postoperative PFF. A retrospective review of primary THAs performed at a single center from January 2011 to December 2018 included 3,315 hips (2,326 patients). Cementless stems were classified according to their design geometry using the system proposed by Radaelli et al. The incidence of PFF was compared between flat taper porous-coated stems (type A), rectangular taper grit-blasted stems (type B1), and quadrangular taper hydroxyapatite-coated stems (type B2). Multivariate regression analyses were performed to identify independent factors related to PFF. The mean follow-up duration was 61 months (range, 12‒139 months). Overall, 45 (1.4%) postoperative PFFs occurred. The incidence of PFF was significantly higher in type B1 stems than in type A and type B2 stems (1.8 vs. 0.7 vs. 0.7%; P=0.022). Additionally, more surgical treatments (1.7 vs. 0.5 vs. 0.7%; P=0.013) and femoral revisions (1.2 vs. 0.2 vs. 0%; P=0.004) were required for PFF in type B1 stems. After controlling for confounding variables, older age (P<0.001), diagnosis of hip fracture (P<0.001), and use of type B1 stems (P=0.001) were significant factors associated with PFF. Type B1 rectangular taper stems were found to have higher risks for postoperative PFF and PFF requiring surgical management than type A and type B2 stems in THA. Femoral stem geometry should be considered when planning for cementless THA in elderly patients with compromised bone quality

The 10 year survivorship of THR is generally over 95%. However, the incidence of revision is usually higher in year one. The most common reason being dislocation which at least in part is driven by inadequate range of motion (ROM) leading to impingement, subluxation and ultimately dislocation which is more frequently posterior. ROM is affected by patient activity, bone and component geometry, and component placement. To reduce the incidence of dislocation, supported by registry data, there has been an increase in the use of so-called ‘lipped’ liners. Whilst this increases joint stability, the theoretical ROM is reduced. The aim of this study was to investigate the effect of lip placement on impingement. A rigid body geometric model was incorporated into a CT scan hemi-pelvis and femur, with a clinically available THR virtually implanted. Kinematic activity data associated with dislocation was applied, comprising of five posterior and two anterior dislocation risk activities, resulting from anterior and posterior impingement respectively. Cup inclination and anteversion was varied (30°-70°, 0°-50° respectively) to simulate extremes of clinical outcomes. The apex position of a ‘lipped’ liner was rotated from the superior position, anteriorly and posteriorly in steps of 45°. Incidence and location of implant and bone impingement was recorded in 5346 cases generated. A liner with the lip placed superior increased the occurrence of implant-implant impingement compared with a neutral liner. Rotation of the lip from superior reduced this incidence. This effect was more marked with posterior rotation which after 90° reduced anterior impingement to levels similar to a neutral liner. Complete inversion of the lipped liner reduced impingement, but this and anterior rotation both negate its function – additional stability. This study comprises one bone geometry and component design and one set of activity profiles. Nevertheless, it indicates that appropriate lip placement can minimise the likelihood of impingement for a range of daily activities whilst still providing additional joint stability

Cementless stem designs in total hip arthroplasty differ in relation to geometry and area of fixation. We utilised radiostereometric analysis (RSA) to evaluate the 2-year migration of a novel, short, proximally coated femoral stem. 30 participants undergoing primary total hip replacement for any cause (rheumatoid or inflammatory arthritis, osteoarthritis) were prospectively recruited in this study. Osteoporotic patients and cases of suspected infection were excluded. All patients received a short blade stem, proximally coated with a reduced lateral shoulder and narrow triple taper geometry to minimise bone removal. RSA radiographs were performed post-operatively and at 6 weeks, 6 months, 1- and 2 years. The Harris Hip Score (HHS), Oxford Hip Score (OHS) and EQ-5D were collected at baseline and at 2 years post-operatively. The stability of implants and complications were captured during each follow-up visit. A total of 14 female and 16 male patients were recruited with a mean age of 64.8 (range 47 to 75). At two years the mean subsidence of the stem was 0.34 mm (SD 0.62) and the total migration 0.74 mm (SD 0.60). The mean medial translation at two years was 0.059 (0.24) and the mean anterior translation 0.12 (0.59) respectively. Baseline PROM scores improved significantly at 2-years from pre-operatively (median and interquartile range): HHS from 33 (18.25) to 92 (19), EQ5D from 0.5 (0.35) to 0.94 (0.17), OHS from 21 (18.25) to 42 (4.25). P-value for all comparisons was <0.001. 2-year follow up data revealed no complications. There were no stem revisions in study participants and no heterotopic ossifications were identified on radiographs. 2-year migration results of a cementless, short blade, proximally coated tapered femoral stem using RSA, showed the stem exhibits a predictable migration pattern and achieves initial stability. This is highly likely to translate to mid and long-term stability, which needs to be corroborated by long-term outcome studies. Furthermore, participants demonstrated excellent clinical, patient reported and radiological outcomes after 2 years of follow up to support expansion in the use of this prosthesis

Dual-mobility (DM) bearings are effective to mitigate dislocation in revision total hip arthroplasty (THA). However, data on its use for treating dislocation is scarce. Aim of this study was to compare DM bearings, standard bearings and constrained liner (CL) in revision THA for recurrent dislocation and to identify risk factors for re-dislocation. We reviewed 100 consecutive revision THAs performed for dislocation from 2012 and 2019. 45 hips (45%) received a DM construct, while 44 hips (44%) and 11 hips (11%) had a standard bearing and CL, respectively. Rates of re-dislocation, re-revision for dislocation and overall re-revision were compared. Radiographs were assessed for cup positioning, restoration of centre of rotation, leg length and offset. Risk factors for re-dislocation were determined by cox regression analysis. Modified Harris hip scores (mHHS) were calculated. Mean follow-up was 53 months (1 to 103). DM constructs were used more frequently in elderly patients (p=0.011) and hips with abductor deficiency (p< 0.001). The re-dislocation rate was 11.1% for DM bearings compared with 15.9% for standard bearings and 18.2% for CL (p=0.732). Revision-free survival for DM constructs was 83% (95% CI 0.77 – 0.90) compared to 75% (95% CI 0.68 – 0.82) for standard articulations and 71% (95% CI 0.56 – 0.85) for CL (p=0.455). Younger age (HR 0.91; p=0.020), lower comorbidity (HR 0.42; p=0.031), smaller heads (HR 0.80; p=0.041) and cup retention (HR 8.23; p=0.022) were associated with re-dislocation. Radiological analysis did not reveal a relationship between restoration of hip geometry and re-dislocation. mHHS significantly improved from 43.8 points to 65.7 points (p<0.001) with no differences among bearing types. Our findings suggest that DM bearings do not sufficiently prevent dislocation in revision THA for recurrent dislocation. Reconstruction of the abductor complex may play a key role to reduce the burden in these high-risk patients

Short stems have been developed to conserve bone stock, especially in younger populations undergoing a total hip arthroplasty (THA), and showed similar functional outcomes compared to conventional stems. Recent literature suggested that stem length might be an independent risk factor for acute periprosthetic femoral fracture in direct anterior THA (1) or with different short stem designs (2). The purpose of the present study was to compare the incidence of acute periprosthetic femoral fractures, between stems of the same manufacture (Taperloc microplasty vs Taperloc complete), which have the same stem characteristics, except for the stem length which is 35 mm shorter in Taperloc microplasty during posterior and lateral THA. Our institution's arthroplasty database was searched for all primary total hip arthroplasties utilizing short femoral stems performed between August 2016 and August 2023. Pre-operative X-rays for each case were analysed to characterize the proximal femoral geometry, specifically the canal bone ratio (CBR) and canal flare index (CFI). Data analysis was performed to identify risk factors for periprosthetic fractures. For the time period assessed, 2107 femoral stems (Taperloc Microplasty:1727, Taperloc complete: 380) were implanted. Females constituted 53% of the cohort. The average patient age was 70±11 years. The periprosthetic fracture rate was 0.94%, with 20 periprosthetic fractures (Taperloc Microplasty:17, Taperloc complete: 3) excluding 2 greater trochanteric fractures (1 at each group), identified at follow-up of three months. There was no significant difference between the periprosthetic fracture rates between the two stems (0.98% vs 0.79%, p>0.72) The multivariate regression analysis demonstrated that the stem length, CBR, CFI, age, and gender were not risk factors for periprosthetic fracture. The present study demonstrated that both Taperloc Microplasty and Taperloc complete stems had similar rates of periprosthetic fractures, and the stem length was not a risk factor for a periprosthetic fracture during uncemented THA. 1. Tamaki T, Cementless Tapered-Wedge Stem Length Affects the Risk of Periprosthetic Femoral Fractures in Direct Anterior Total Hip Arthroplasty. J Arthroplasty. 2018 Mar;33(3):805-809. 2. Staunton P. Acute Periprosthetic Hip Fracture with Short Uncemented Femoral Stems. J Arthroplasty 2024 accepted

The Exeter. ™. V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems. A systematic literature search was performed adhering to PRISMA criteria. In parallel we performed a retrospective single centre study of Exeter. ™. V40 femoral stem prosthetic fractures between April 2003– June 2020. There are 25 reported cases of such prosthetic fractures confined to small case series and case reports within the literature. We report an additional 19 cases to the literature (mean age 66.3 ± 11.7 years; 12 female [63%]; body mass index 32.9 ± 5.9 kg/m. 2. ). The mean time from index procedure to fracture was 7.8 years (2.5–16.3, ±3.6). Exeter V40 stem fracture incidence was 0.27%. Incidence was significantly higher in 125 mm length stems compared to ≥150 mm length stems (1.26% vs 0.13%, respectively, p <0.001) and revision arthroplasty (1.209% vs 0.149%, p <0.001). When comparing different stem length cohorts, 125-mm short-stem were associated with stem body fractures (92% vs 29%, p = 0.0095), earlier time to fracture (6.2 vs 11.0 years, p = 0.0018), younger patient age at time of fracture (62.7 vs 72.6 years old, p = 0.037) and female sex (75% vs 43%, p = 0.33). This case series in conjunction with the systematic review provides evidence stem morphology plays a role in femoral implant fracture. This complication remains rare, although we report a significantly higher incidence at up to 17 years follow-up than in the literature. As femoral geometries remain the same, increasing BMIs in THR patients should raise concern. Short 125 mm length Exeter V40 stems undoubtedly have a role in restoring anatomy and biomechanics in smaller femoral geometries, although the surgeon has to appreciate the higher risk of stem fracture and the associated predisposing factors which may necessitate meticulous surgical technique and planning

Aims. The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems. Methods. A systematic literature search was performed adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. In parallel, we performed a retrospective single centre study of Exeter V40 femoral stem prosthetic fractures between April 2003 and June 2020. Results. There are 25 reported cases of such prosthetic fractures confined to small case series and case reports within the literature. We report an additional 19 cases to the literature (mean age 66.3 years (SD 11.7); 12 (63%) females; BMI 32.9 kg/m. 2. (SD 5.9)). The mean time from index procedure to fracture was 7.8 years (SD 3.6; 2.5 to 16.3). Exeter V40 stem fracture incidence was 0.15% and 1.21% for primary and revision arthroplasty, respectively. Incidence was significantly higher in revision arthroplasty (p < 0.001) and 125 mm length stems compared to ≥ 150 mm length stems (1.25% vs 0.13%, respectively; p < 0.001). When comparing different stem length cohorts, 125 mm short-stems were associated with stem-body fractures (92% vs 29%; p = 0.0095), earlier time to fracture (6.2 years vs 11.0 years; p = 0.0018), younger patient age at time of fracture (62.7 years vs 72.6 years; p = 0.037), and female sex (75% vs 43%; p = 0.326). Conclusion. This complication remains rare, although we report a significantly higher incidence at up to 17 years follow-up than in the literature. Short 125 mm length Exeter V40 stems undoubtedly have a role in restoring anatomy and biomechanics in smaller femoral geometries, although the surgeon has to appreciate the higher risk of stem fracture and the associated predisposing factors which may necessitate particular attention to surgical technique and planning. Cite this article: Bone Jt Open 2021;2(6):443–456

Aims

The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in ‘cement-in-cement’ revision cases. It has, however, been used ‘off-label’ as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR.

Aims. Radiostereometric analysis (RSA) studies of vitamin E-doped, highly crosslinked polyethylene (VEPE) liners show low head penetration rates in cementless acetabular components. There is, however, currently no data on cemented VEPE acetabular components in total hip arthroplasty (THA). The aim of this study was to evaluate the safety of a new cemented VEPE component, compared with a conventional polyethylene (PE) component regarding migration, head penetration, and clinical results. Patients and Methods. We enrolled 42 patients (21 male, 21 female) with osteoarthritis and a mean age of 67 years (. sd. 5), in a double-blinded, noninferiority, randomized controlled trial. The subjects were randomized in a 1:1 ratio to receive a reverse hybrid THA with a cemented component of either argon-gas gamma-sterilized PE component (controls) or VEPE, with identical geometry. The primary endpoint was proximal implant migration of the component at two years postoperatively measured with RSA. Secondary endpoints included total migration of the component, penetration of the femoral head into the component, and patient-reported outcome measurements. Results. In total, 19 control implants and 18 implants in the VEPE group were analyzed for the primary endpoint. We found a continuous proximal migration of the component in the VEPE group that was significantly higher with a difference at two years of a mean 0.21 mm (95% confidence interval (CI) 0.05 to 0.37; p = 0.013). The total migration was also significantly higher in the VEPE group, but femoral head penetration was lower. We found no difference in clinical outcomes between the groups. Conclusion. At two years, this cemented VEPE component, although having a low head penetration and excellent clinical results, failed to meet noninferiority compared with the conventional implant by a proximal migration above the proposed safety threshold of RSA. The early proximal migration pattern of the VEPE component is a reason for continued monitoring, although a specific threshold for proximal migration and risk for later failure cannot be defined and needs further study. Cite this article: Bone Joint J 2019;101-B:1192–1198

Aims

When performing revision total hip arthroplasty using diaphyseal-engaging titanium tapered stems (TTS), the recommended 3 to 4 cm of stem-cortical diaphyseal contact may not be available. In challenging cases such as these with only 2 cm of contact, can sufficient axial stability be achieved and what is the benefit of a prophylactic cable? This study sought to determine, first, whether a prophylactic cable allows for sufficient axial stability when the contact length is 2 cm, and second, if differing TTS taper angles (2° vs 3.5°) impact these results.