Stem In Total Hip Arthroplasty Research Articles

Intraoperative complications in total hip arthroplasty using a new cementless femoral implant (SP-CL\xae)

BackgroundConsidering the excellent results already achieved in total hip arthroplasty (THA), new implants must be at least as safe as currently used implants and lead to longer survival. A new cementless femoral stem, SP-CL®, has been introduced. The aim of this study is to evaluate intraoperative complications and assess the risk factors of THA with the SP-CL® implant.Materials and methodsAll THA patients who were operated on using the SP-CL® (LINK, Hamburg, Germany) implant between 2015 and 2018 were included in the analysis. Data were collected from medical records from national and hospital electronic databases. Radiological measurements were made from standard pre- and postoperative radiographs.ResultsA total of 222 THA were performed using the SP-CL® implant. The average age of the patients was 56 years (14–77 years). There were 1 transient sciatic nerve injury, 1 acetabular fracture, and 11 (5.0%) intraoperative femoral fractures (IFF), of which 7 were treated with cerclage wire or titanium band during the operation while the other fractures were treated conservatively. None of the IFF patients were revised due to fracture during the follow-up period (one revision due to infection). The radiographic morphology of proximal femur was associated with increased risk of IFF (p = 0.02).ConclusionsThe results of the current study demonstrate a 5% incidence of IFF when using the LINK SP-CL® femoral stem in THA. The radiographic morphology of the proximal femur was an important predictor of IFF and should be assessed when using SP-CL®.Level of evidenceLevel 4.

Calcar-Guided Short Stems in Total Hip Arthroplasty: A Two-Year Prospective Multicentre Study

Background: Calcar-guided short-stem Total Hip Arthroplasty (THA) is increasingly being used to preserve proximal femoral bone stock for potential later revision surgery. Objective: In this study, we aimed to expand the clinical evidence on calcar-guided short-stem THA used in daily clinical practice, focusing on clinical outcomes as well as radiographic signs of stress shielding and femoral bone loss. Methods: In a prospective multicentre study, we enrolled 213 patients with a total of 224 THAs for mainly degenerative indications. The patients were examined clinically and radiographically 6 to 12 weeks, 12 months, and 24 months postoperatively. Results: All clinical outcomes improved significantly over the first 6 to 12 weeks compared to preoperative values (P < 0.001). At 24 months, the mean Harris hip score was 95.3 ± 6.7, and the mean visual analogue scale for pain was 1.0 ± 1.7 under load and 0.5 ± 1.3 at rest. We observed early distal stem migration in six patients and late migration in one patient. Additionally, we found 16 cases of radiographic signs indicative of stress shielding. Four patients required stem revision surgery: two for stem migration, one for periprosthetic fracture, and one for deep infection. Conclusion: Overall, calcar-guided short-stem THA resulted in excellent clinical outcomes after two years of follow-up, and the radiographs revealed few signs of stress shielding. We, therefore, regard calcar-guided short-stem THA as a safe and effective treatment alternative in daily clinical practice.

A Large-Scale Fifteen-Year Minimum Survivorship of a Cementless Triple Tapered Femoral Stem

BackgroundThis study reports the long-term outcomes of a metaphyseal fit-and-fill cementless femoral component in total hip arthroplasty (THA) with a follow-up of 15-19 years. MethodsWe conducted a retrospective review of 376 consecutive THAs (345 patients), using a triple tapered stem performed between 2000 and 2003 with a view to assessing survivorship and radiological and functional outcomes. Images were assessed for initial alignment, terminal osteolysis, or subsidence, while clinical outcomes were assessed using the St Michael’s Hip Score. ResultsForty-five (11.9%) hips were lost to follow-up, 20 (5.31%) had died before our 15-year cutoff follow-up, and 4 (1.06%) had declined follow-up early on, leaving 307 hips (81.64%, 276 patients) available for both clinical and radiological follow-up at a minimum of 15 years (range 15-19). The mean age at the time of operation was 49.6 years (range 19-71) and the cohort included 131 (42.67%) male and 145 (47.23%) female patients. Seven stems (2.28%) were revised: 4 due to periprosthetic fractures, 2 for periprosthetic joint infection, and 1 for adverse reaction to metal debris at the trunnion. The St Michael’s Hip Score improved from 14.2 (range 9-23) preoperatively to 22.3 (range 13 to 25) at the last documented follow-up (P = .000). Kaplan-Meier survivorship with stem revision for any reason as the end point was 97.70%. Worst-case scenario Kaplan-Meier survivorship, where all lost to follow-up are considered as failures, was 85.3%. No stem was revised for aseptic loosening. ConclusionThis triple tapered stem in THA shows excellent survivorship beyond a minimum of 15 years.

AB151. The varus cemented femoral stem in total hip arthroplasty: predictors and the femoral access ratio

AB151. The varus cemented femoral stem in total hip arthroplasty: predictors and the femoral access ratio

Modular stem in total hip arthroplasty for patients with trochanter valgus deformity: surgical technique and case series

BackgroundTrochanter valgus deformity (TVD) is a rare condition of total hip arthroplasty (THA). Femoral osteotomy could be required in correcting the deformity to implant femoral stem in severe TVD. In this study, we described one unpublished technique of reverse sleeve of S-ROM to get through the complex situation. This study aimed to summarize and evaluate its technical challenges, safety and effectiveness.MethodsFrom January 2006 to December 2014, we enrolled patients whose sleeves were implanted towards the great trochanter in THA with TVD. Their demographics, perioperative and postoperative information were recorded. To explore its indication, we measured and analyzed the ratio of greater trochanter/lesser trochanter (G/L ratio) and trochanter valgus angle (TVA).ResultsTwelve patients (1 male and 11 female, average age 42.30 ± 10.23) had mean follow-up of 6 years. Among them, only two patients had intraoperative femoral fracture. The survivorship of femoral prosthesis was 100%. The Harris hip score (HHS) increased from preoperative 34.31 ± 14.43 to postoperative 84.12 ± 11.33. All patients’ G/L ratio were larger than 1.50.ConclusionsThe reverse sleeve of S-ROM was a reliable method for the patients with severe TVD, which brought satisfying clinical outcomes in mid-term follow-up.

Anatomical Femoral Stem in Total Hip Arthroplasty

Anatomical Femoral Stem in Total Hip Arthroplasty

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

The consensus that bone stock preservation and optimal restoration of offset and leg length is important in total hip arthroplasty is now widespread, especially for young and active patients. Short stems seem promising in this aspect, though implant stability is still of concern. This study looked at the migration pattern of the Optimys short stem through RSA analysis. 40 patients were included. RSA images were made directly postoperatively (within 5 days), at 6 weeks and at 3, 6, 12 and 24 months. Double examinations were made for precision measurement. HOOS and pain scores were obtained preoperatively and at 2 years. 4 patients were excluded due to protocol violation and 1 patient was excluded for RSA analysis with a CN number >110. 2 patients were lost to follow-up after 3 and 6 months (n = 1 lost, n = 1 deep infection, respectively). Mean age was 60 years with a mean BMI of 27. RSA analysis of 34 patients showed a significant initial median proximodistal translation (subsidence) of 0.21 mm (IQR 0.64-0.06) and anteversion-retroversion rotation of 0.59° (IQR 0.01-1.34) at 6 weeks, after which the stem stabilises and showed no further significant movement. Median migration in other directions was small. 4 patients had an initial subsidence of >2 mm, all showed secondary stabilisation. HOOS outcomes were satisfactory, with the domain symptoms and pain showing a median score of 95/100 at 2 years. After initial migration the Optimys achieves secondary stabilisation, suggesting low risk on long-term aseptic loosening. NL47055.048.13.

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

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. 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 48months 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. HHS increased significantly direct postoperatively (p < 0.001). At the second follow-up the average caudal migration was 0.42 ± 0.52mm (range: 0.00-2.85mm) (p < 0.001). A total of 14 patients underwent a caudal migration greater than 1.5mm until 48months. The initial varus and valgus tilts within the first 3months 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. 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 48months. Likewise, no aseptic early loosening was detected throughout the study period, which indicates good osseointegration of the short stem prosthesis.

Fixation, sex, and age: highest risk of revision for uncemented stems in elderly women — data from 66,995 primary total hip arthroplasties in the Norwegian Arthroplasty Register

Background and purpose — There is no consensus on best method of fixation in hip arthroplasty. We investigated different modes of fixation in primary total hip arthroplasty (THA) and the influence of age and sex, to assess need for a differentiated approach.Patients and methods — The study was based on data from the Norwegian Arthroplasty Register in the period 2005–2017. Included were all-cemented, all-uncemented, reverse hybrid (uncemented stem and cemented cup), and hybrid (cemented stem and uncemented cup) THA designs that were commonly used, contemporary and well documented, using different causes of revision as endpoints.Results — From the included 66,995 primary THAs, 2,242 (3.3%) were revised. Compared with all-cemented THAs, all-uncemented had a higher risk of revision due to any cause (RR 1.4; CI 1.2–1.6), mainly due to an increased risk of periprosthetic fracture (RR 5.2; CI 3.2–8.5) and dislocation (RR 2.2; CI 1.5–3.0). Women had considerably higher risk of revision due to periprosthetic fracture after all-uncemented THA (RR 12; CI 6–25), compared with cemented. All-uncemented THAs in women of age 55–75 years (RR 1.3; CI 1.0–1.7) and over 75 years of age (RR 1.8; CI 1.2–2.7), and reverse hybrid THAs in women over the age of 75 (RR 1.5; CI 1.1–1.9) had higher risk of revision compared with cemented. Hybrid THAs (RR 1.0; CI 0.9–1.2) and reverse hybrid THAs (RR 1.0; CI 0.7–1.3) had similar risk of revision due to any cause as cemented THAs.Interpretation — Uncemented stems (all-uncemented and reverse hybrid THAs) had increased risk of revision in women over 55 years of age, mainly due to periprosthetic fracture and dislocation, and should probably not be used in THA in these patients.

Effect of transtrochanteric rotational osteotomy on impingement and contact state of a femoral implant in conversion total hip arthroplasty — Retrospective simulation study

BackgroundThe transtrochanteric rotational osteotomy is a common osteotomy for osteonecrosis of the femoral head, although the results of conversion total hip arthroplasty after the osteotomy are controversial. We evaluated how deformities in the proximal femur after the osteotomy affect hip impingement and the contact state of the stem in total hip arthroplasty. MethodsWe retrospectively reviewed 35 hips (24 men) that had undergone the transtrochanteric rotational osteotomy for osteonecrosis of the femoral head (TRO-group) and compared them with 31 contralateral, unoperated hips (Primary group). The distance between the anterior and posterior greater trochanter at the cutting point of the femur, defined as the greater trochanter width and the contact area of the femoral implant surface with cortical bone were measured by CT-based three-dimensional templating software. We also calculated the hip range of motion in conversion total hip arthroplasty and analyzed the correlations between the greater trochanter width and the range of motion. FindingsThe number of bony-impingement cases was significantly greater, and the range of motion in flexion, internal rotation and external rotation was significantly less in TRO-group. There was a significant negative correlation between the greater trochanter width and range of motion of internal rotation. There were no significant differences between two groups in percentages of femoral-implant contact area. InterpretationsThe femoral implant fixation appears to be satisfactorily fixed in all zones in conversion total hip arthroplasty. However, the greater attention should be paid to minimizing bony impingement, especially on the anterior side, in conversion total hip arthroplasty.

Minimum 15-Year Results of a Dual-Offset Uncemented Femoral Stem in Total Hip Arthroplasty

BackgroundThe aim of the present study is to assess the long-term clinical and radiological outcomes of a proximal porous-coated, dual-offset, tapered titanium alloy uncemented stem at a minimum of 15 years of follow-up. MethodsWe reviewed 210 total hip arthroplasties (in 193 patients) performed between 1996 and 1999 and followed prospectively in our database who received the Synergy stem. We report a Kaplan-Meier survival analysis as well as the Harris Hip Score, the Western Ontario and McMaster University Arthritis Index, and the Short Form Health Survey-12 scores. Radiographs were evaluated for evidence of subsidence, osteolysis, osteointegration, or loosening. ResultsThe average follow-up was 16 years (range, 15-17.7 years). Kaplan-Meier survival analysis with revision of stem for aseptic mechanical loosening (1 stem) as the end point revealed a cumulative survival rate of 99.5% at 16 years. The Harris Hip Score, the Western Ontario and McMaster University Arthritis Index, and the Short Form Health Survey-12 physical scores were all significantly improved (P < .001) from the preoperative period to latest follow-up. Minor osteolysis was observed proximally in 14 hips (6.6%) with no osteolysis distal to the porous coating. ConclusionTo our knowledge, this study represents the largest series reporting the longest clinical follow-up of this third-generation, dual-offset, proximal ingrowth, tapered cementless stem. The Synergy stem design has achieved excellent clinical outcomes, predictable osteointegration, and outstanding survivorship of 99.5% at a minimum of 15 years follow-up, representing the standard for femoral stems at our institution.

Short stems reproduce femoral offset better than standard stems in total hip arthroplasty: a case-control study

In total hip arthroplasty (THA), altering the original offset can lead to poor outcome or even complications or revision when the changes are too great. The aim of the present study was to compare femoral offset between short and standard stems. The hypothesis was that the short stems studied provide better control of post-operative femoral offset. We retrospectively reviewed 100 consecutive THAs using uncemented optimys™ short stems (Mathys, Bettlach, Switzerland), matched to 100 standard stem THAs performed during the same period. The primary endpoint was femoral offset; secondary endpoints were the limb length and cervico-diaphyseal angle. The mean femoral offset increased by 6.0 ± 7.2mm overall (p < 0.0001), 4.7 ± 6.7mm in the short-stem group (p < 0.0001), and 7.2 ± 7.5mm in the standard stem group (p < 0.0001), with a significant inter-group difference (p = 0.0152). Limb length showed no significant inter-group difference (p = 0.8425). Cervico-diaphyseal angle was increased by surgery overall, and more by standard than by short stems (p < 0.05). Measurement of femoral offset revealed significant lateralization. It is critical that offset should be maintained in THA. The technique we use increases femoral offset, but the present study showed less increase using short than standard stems. These findings must be borne in mind to achieve good clinical outcome.

Restoring femoral offset and leg length; the potential of a short curved stem in total hip arthroplasty

BackgroundTotal hip arthroplasty (THA) is a very successful procedure in orthopedics. Still polyethylene wear and gait deficits are limiting the clinical success.It is important to reconstruct leg length (LL) and femoral offset (FO) anatomically in order to have the best possible result of a THA. Gait deficits can arise due to leg length discrepancy as well as changes in the abductor moment arm. In THA, LL and FO are strongly determined by the orientation, size and geometry of the femoral stem. MethodsThis radio-anatomical study used the data of a prospective cases series of 112 patients who underwent 126 primary THAs and had completed a 1-year follow-up examination. FO and LL were compared between the conventional straight stem in vivo and a computed simulated implantation of a short curved stem, using the pre- and postoperative pelvic radiographs of the same patients. ResultsIn this simulation of the short curved stem statistically significantly restored native FO (p = 0.010) and LL (p = 0.000) better, compared to the conventional straight stem. ConclusionsThus, the short curved stem restores FO and LL better, and could potentially prevent gait deficits.

Long-Term Outcomes of Ultra-Short Metaphyseal-Fitting Anatomic Cementless Femoral Stem in Total Hip Arthroplasty With Ceramic-on-Ceramic Articulation for Young Patients

BackgroundThe aim of this study is to assess the long-term outcomes of this specific stem in patients younger than 50 years old, with regard to clinical and radiographic outcomes, survivorship, and complication rate. MethodsTwo hundred thirty-nine consecutive series of patients (324 hips) who were younger than 50 years old at the time of surgery were enrolled in the study. Osteonecrosis (50%) and dysplastic hip (34%) were most common diagnoses. Patients were informed to use crutches or walker for 4 weeks to protect the femoral component against rotational stress. The mean follow-up was 15.6 years (range 14-17). ResultsAt the latest follow-up, the mean Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index score, and University of California, Los Angeles activity score were 93 points, 13 points, and 7 points, respectively. Three patients (1.3%) had moderate thigh pain. All of the acetabular components and 321 (99%) femoral stems were solidly fixed at the time of the latest follow-up. Three stems (0.9%) were revised for aseptic loosening. Two hips (0.6%) had a dislocation and 2 hips (0.6%) had a periprosthetic fracture. Ceramic fracture or osteolysis was not found in any hip at the time of the final follow-up. Survival rate of the femoral component was 99.1% (95% confidence interval 94-100) and that of the acetabular component was 100% (95% confidence interval 94-100) at 15.6 years. ConclusionIn this series, THA using an ultra-short metaphyseal-fitting anatomic cementless femoral stem provided excellent long-term clinical and radiographic results in patients younger than 50 years old. Furthermore, our initial theoretical concerns about early aseptic loosening due to the absence of distal stem fixation were not justified.

The DePuy Proxima™ short stem for total hip arthroplasty - Excellent outcome at a minimum of 7 years.

Metaphyseal, proximally anchored uncemented stems for total hip arthroplasty provide bone preservation and decrease the incidence of proximal stress shielding and thigh pain. Our study investigated the clinical and radiological outcome of the DePuy Proxima™ short stem at a minimum of 7 years. Eighty-one consecutive patients (86 procedures) under the age of 70 undergoing primary total hip replacement at two arthroplasty centres were enrolled. Follow-up was clinical (Harris Hip Score (HHS), thigh pain and satisfaction) and radiological (subsidence, malalignment and loosening) at 6 months and yearly thereafter. Average age was 50 (range 32-65) with 79% (68 of 86) being male. Preoperative diagnosis included primary osteoarthritis (OA) 36%, avascular necrosis of femoral head 51%, dysplasia 9% and post-traumatic OA 4%. HHS improved 51 points at latest follow-up (from 40 to 91). We had 3.5% (3 of 86) periprosthetic fractures, one requiring revision. We had one dislocation, no infections and no thigh pain. Malalignment rate (≥5° off neutral) was 12% (10 of 86), not affecting clinical results. Overall stem survival was over 97% at 7 years. The DePuy Proxima provides excellent clinical results at a minimum of 7 years post-operatively.

Custom Cementless Femoral Stems in Total Hip Arthroplasty

AbstractObtaining appropriate prosthetic fit in cementless total hip arthroplasty can be challenging in cases with disparity between the femoral and metaphyseal diameters of the femur or cases of complex deformity. One solution has been to utilize a custom femoral component in total hip arthroplasty. The long-term results of this option with respect to femoral morphology are limited. This cohort was analyzed to determine the survivorship, functional results using Harris Hip Scores (HHSs), and complication rates using these implants. Survivorship and complications were evaluated based on the proximal femoral anatomy and severity of arthritis. The authors retrospectively reviewed 73 cases of custom femoral implants in total hip arthroplasties by a single surgeon. The average age of patients at index surgery was 58.06 years (range, 36.00–73.75 years). The mean follow-up was 8.59 years (range, 0.17–20.33 years) with a minimum of 2-year follow-up required for analysis of HHS data. There were 8 failures at a mean of 67.68 months (range, 2.04–135 months). The reasons for revision were infection (2), osteolysis (1), periprosthetic fracture (3), osteolysis and aseptic loosening (1), and polyethylene wear (1). The mean preoperative HHS was 55.38 (range, 31–90). The mean follow-up HHS was 93.10 (range, 38–100) with a mean improvement of 37.44 (p &lt; 0.0001). Complications included infection (3), fracture (6), and dislocation (3). Preoperative Dorr classification A (n = 44), B (n = 24), and C (n = 1) and Kellgren–Lawrence grades I (n = 0), II (n = 2), III (n = 7), and IV (n = 60) were not predictive of failure or revision (p = 0.45, p = 0.6). There was a near significant association between Dorr classification B femur fractures requiring revision (p &lt; 0.053). Kaplan–Meier predicted survivorship was 20.33 years with revision for any reason as the endpoint and total overall survivorship of 81.7%. Custom cementless femoral stems provide satisfactory survivorship and improvement in hip scores in a variety of patients undergoing cementless total hip arthroplasty. Fracture rates are higher in Dorr class B femurs. The level of evidence was IV.

Comparison of Patient-Reported Outcomes of Total Hip Arthroplasty between a Neck-Preserving Short-Stem Implant and a Conventional Neck-Sacrificing Implant

AbstractFemoral neck-preserving short- (NPS) stem implants for total hip arthroplasty (THA) bear several advantages over longer-stem implants, such as native hip structure preservation and improved physiological loading. However, there still is a gap of knowledge regarding the potential benefits of a short-stem design over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). The authors investigated the differences in PROs between a neck-sacrificing stem design and NPS stem design arthroplasty. They hypothesized that PROs of NPS stem THA would be higher in the medium-term in comparison to the neck-sacrificing implant system. Neck-sacrificing implant patients (n = 90, age 57 ± 7.9 years) and a matched (body mass index [BMI], age) cohort group of NPS implant patients (n = 105, age 55.2 ± 9.9 years) reported both preoperative and postoperative hip disability and osteoarthritis outcome scores (HOOS). Average follow-up was 413 ± 207 days (neck sacrificing implant) and 454 ± 226 days (NPS implant). The authors applied multivariate analysis of variance (MANOVA) and Mann–Whitney tests for statistical analyses. Significance levels were Holm–Bonferroni adjusted for multiple comparisons. HOOS Subscores increased significantly after surgery independent of implant type (p &lt; 0.001). There was a significant time by surgery interaction (p = 0.02). Follow-up HOOS subscores were significantly higher in the NPS implant group: symptoms (p &lt; 0.001), pain (p &lt; 0.001), activities of daily living (ADL; p = 0.011), sports and recreation (p = 0.011), and quality of life (QOL; p = 0.007). While long-term studies are required for further investigation, evidence from the current study suggests that NPS implants may provide a significant benefit to primary THA patients, which could be due to physiological loading advantages or retention of bone tissue.

Anatomic grooved stem mitigates strain shielding compared to established total hip arthroplasty stem designs in finite-element models

Aseptic loosening remains a major problem for uncemented femoral components in primary total hip arthroplasty (THA). Ideally, bone adaptation after THA manifests minimally and local bone density reduction is widely avoided. Different design features may help to approximate initial, post-THA bone strain to levels pre-THA. Strain-shielding effects of different SP-CL stem design features are systematically analyzed and compared to CLS Spotorno and CORAIL using finite element models and physiological musculoskeletal loading conditions. All designs show substantial proximal strain-shielding: 50% reduced medial surface strain, 40–50% reduction at lateral surface, >120 µm/m root mean square error (RMSE) compared to intact bone in Gruen zone 1 and >60 µm/m RMSE in Gruen zones 2, 6, and 7. Geometrical changes (ribs, grooves, cross sections, stem length, anatomic curvature) have a considerable effect on strain-shielding; up to 20%. Combinations of reduced stem stiffness with larger proximal contact area (anatomically curved, grooves) lead to less strain-shielding compared to clinically established implant designs. We found that only the combination of a structurally flexible stem with anatomical curvature and grooves improves strain-shielding compared to other designs. The clinical implications in vivo of this initial strain-shielding difference are currently under evaluation in an ongoing clinical analysis.

Photoelastic Analysis of Two Different Cementless Femoral Stems for Total Hip Arthroplasty in a Canine Model

Objectives The aim of this article was to analyse and compare internal stress generated at different points of a femoral photoelastic model after insertion and axial load application using two different cementless femoral stems for total hip arthroplasty in dogs: a collared stem combined with limited textured surface and absence of grooves and a collarless stem with fully textured surface and grooves. Methods Ten femoral photoelastic models, divided into two groups, were created using two different designs of cementless femoral stems. The models were submitted to axial loading on the femoral head in a universal test machine. The internal stress (kPa) around the femoral stems was evaluated at seven predetermined points using a transmission polariscope. Results The internal stress at the femoral calcar was larger in the models with collared stem combined with limited textured surface and absence of grooves (p &lt; 0.05). No differences were identified between the groups in the other points (p &gt; 0.05), corresponding to the tip of the stems and proximal lateral region of the femur. Conclusions The collar of femoral stem combined with the absence of grooves and more limited textured surface increase the axial load transmission to the femoral calcar, and in vivo, it may act to reduce complications, such as subsidence and stress shielding. However, other biomechanical tests and clinical evaluations must be performed to determine other important aspects for the implantation of these prostheses.

Cement Burn of the Skin During Total Hip Arthroplasty: A Case Series

Bone cement which can reach temperatures of >100°C, is commonly used to fix the femoral stem in total hip arthroplasty (THA). However, reports on skin burns due to bone cement are rare. The primary purpose of this article is to report these rare cases to prevent these complications. Two cases were simultaneous bilateral THA (case A and B) and two cases were unilateral THA (case C and D) are discussed in this case report. In these cases, the maximum thickness of excessive bone cement was >10 mm.