Finite element analysis of mechanical stress in a cementless tapered-wedge short stem in the varus position.

BACKGROUND: In recent years, the use of tapered-wedge short stems has increased due to their ability to preserve bones and tendons. Surgical techniques occasionally result in a varus position of the stem, which is particularly pronounced in short stems. Although the varus position is not clinically problematic, there are reports of an increased incidence of stress shielding and cortical hypertrophy. Thus, we evaluated and examined the acceptable range of varus angles using finite element analysis. METHODS: Patients diagnosed with osteoarthritis of the hip joint who had undergone arthroplasty were selected and classified into three types [champagne-flute (type A), intermediate (type B), and stovepipe (type C)]. Finite element analysis was performed using Mechanical Finder. The model was created using a Taperloc microplasty stem with the varus angle increased by 1° from 0° to 5° from the bone axis and classified into seven zones based on Gruen's zone classification under loading conditions in a one-leg standing position. The volume of interest was set, the mean equivalent stress for each zone was calculated. RESULTS: A significant decrease in stress was observed in zone 2, and increased stress was observed in zones 3 and 4, suggesting the emergence of a distal periosteal reaction, similar to the results of previous studies. In zone 2, there was a significant decrease in stress in all groups at a varus angle ≥ 3°. In zone 3, stress increased from ≥ 3° in type B and ≥ 4° in type C. In zone 4, there was a significant increase in stress at varus angles of ≥ 2° in types A and B and at ≥ 3° in type C. CONCLUSION: In zone 2, the varus angle at which stress shielding above Engh classification grade 3 may appear is expected to be ≥ 3°. Distal cortical hypertrophy may appear in zones 3 and 4; the narrower the medullary cavity shape, the smaller the allowable angle of internal recession, and the wider the medullary cavity shape, the wider the allowable range. Long-term follow-up is required in patients with varus angles > 3°.

No significant differences in 60-day postoperative complication rates between conventional and shortened stems.

PURPOSE: To compare 60-day complication rates, radiographic outcomes, and clinical outcomes following primary THA with conventional versus shortened stems, in a large cohort study. METHODS: The authors reviewed a consecutive series of 800 primary THAs, of which 781 met the inclusion/exclusion criteria: 395 received a conventional stem and 386 received a shortened stem. Intraoperative and postoperative complications were noted. Radiographic and clinical assessments were performed preoperatively and 60 days after surgery. RESULTS: Compared to conventional stems, shortened stems had significantly less intraoperative complications (2.8% vs 0.3%, p = 0.006), but no significant differences in complications that did not require reoperation (1.0% vs 1.3%, p = 0.620), complications that required reoperation without stem revision (2.0% vs 1.0%, p = 0.384), and complications that required stem revision (0.5% vs 0.5%, p = 1.000). Four hips (two from each group) required stem revision and were thus excluded from 60-day assessment. There were no significant differences between groups in subsidence ≥ 3 mm (1.0% vs 0.5%, p = 0.686), alignment (90.3%vs 86.7%, p = 0.192), net change in offset (within 3 mm, 32.3% vs 30.5%, p = 0.097), and limb length discrepancy (3.0 ± 2.6 mm vs 2.9 ± 2.4 mm, p = 0.695). Compared to conventional stems, shortened stems had significantly better preoperative mHHS (56.5 ± 18.5 vs 64.5 ± 13.5, p < 0.001), and significantly lower net improvement in mHHS (29.9 ± 17.1 vs 24.4 ± 15.0, p < 0.001), but no significant differences in postoperative mHHS (87.3 ± 11.9 vs 89.4 ± 9.6, p = 0.109). CONCLUSIONS: There were no significant differences between conventional and shortened stems in terms of postoperative complication rates, radiographic outcomes, and postoperative mHHS. However, patients implanted with shortened stems had less intraoperative complications, but lower net improvement in mHHS. LEVEL OF EVIDENCE: Level IV, Retrospective comparative cohort study.

Are Short Stems Associated With Higher Fracture Rates and Early Revision Rates in Primary Total Hip Arthroplasty? A Noninferiority Analysis.

BACKGROUND: This study aimed to determine if "short" femoral stems were noninferior to (at least as good as) standard-length stems in regards to 90-day periprosthetic fracture and 1-year revision rates. METHODS: Using the MARCQI implant registry, a retrospective study of statewide data was carried out on 64,084 total hip arthroplasties (THAs) between 2012 and 2017. We noticed an increase in the use of "short" uncemented femoral hip stems during THA. Chi-square tests were used to test homogeneity of categorical variables. The covariates included in the analyses were identified using modern epidemiological methods. A Type I probability of 0.05 was used as the level of statistical significance. Inverse probability of treatment weighting (IPTW) was used to mitigate confounding variables. RESULTS: One hundred and seven stems were implanted by surgeons in the state of Michigan. They were classified according to the Khanuja Classification System as Type 2A (trapezoidal, double-tapered calcar loading, n = 3,281), Type 3 (calcar loading with lateral flare, n = 1,898), and Type 4 (shortened, tapered, conventional, n = 19,580), and were compared to standard-length, type 5, stems (n = 33,322) in regards to the 2 outcomes (periprosthetic fractures and 1-year revision rates). Overall, 1-year revision and the 90-day fracture rates were 1.3% (791/57,853) and 1.1% (631/57,968), respectively. Noninferiority was established for all short stems at the clinical threshold of an odds ratio (OR) of 1.5 with P-values <0.05 for 90-day fractures. In regards to 1-year revision rates, noninferiority was also established for Type 3 and 4 stems (P < .05). CONCLUSION: The increased use of "short stems" in Michigan did not lead to increased 1-year revision or 90-day fracture rates.

Could Short Stems THA Be a Good Bone-Saving Option Even in Obese Patients?

Short femoral stems, with preservation of the femoral bone stock, are commonly used in recent years for hip replacement in younger and more active patients. Obesity is increasingly spreading even in the younger population. The aim of this case-series study is to evaluate short stems compared to traditional hip prostheses in the obese population. A total of 77 consecutive patients with a BMI greater than or equal to 30 Kg/m2 were enrolled in this prospective study and were divided into two groups: 49 patients have been implanted with short stems while 28 patients were implanted with traditional stems. All the patients were treated for primary osteoarthritis or avascular necrosis and all the stems were implanted by the same surgeon using a posterior approach. Clinical (Harris Hip Score­HHS, Western Ontario and McMaster Universities Osteoarthritis Index­WOMAC, visual analogue scale­VAS, 12-item Short Form Health Survey­SF-12) and radiographic outcomes were recorded. Radiological evaluations were carried out by three different blinded surgeons. A statistical analysis was performed (chi-square, t-test, Wilcoxon Rank Sum Test, 2-factor ANOVA). At a mean follow-up of 42.6 months both groups showed a marked improvement in pain and in the clinical scores between pre- and post-surgical procedures (p < 0.05) with no significant differences between the two groups at last follow-up (p > 0.05). The radiological evaluations, with high concordance correlation between the three blinded surgeons (ICC consistently >0.80), showed good positioning and osseointegration in all cases, with no significant differences in the restoration of the joint geometry and complications. No revisions were recorded during the follow-up period. In conclusion, short stems appear to be a good option for bone preservation even in obese patients, showing comparable results to traditional implants.

Short Stems and Stemless Shoulder Arthroplasty: Current Concepts Review.

Historically, the shoulder arthroplasty humeral component has been designed for the management of infections, tumours and fractures. In all these cases the stem was needed as a scaffold. Original humeral components were not developed for use in shoulder arthritis, so these designs and derivates had a long stem. The newest humeral implants innovations consist in shortening of the implant, or even removing the whole stem, to rely on stemless fixation at the level of the metaphysis. This implies the advantages of preserved bone stock, less stress shielding, eliminating the diaphyseal stress riser, easier implant removal at revision, and humeral component placement independent from the humeral diaphyseal axis. Nowadays, surgeons try to balance the need for a stable fixation of the humeral component with the potential need for revision surgery. Complications of revision shoulder arthroplasty are related to the need for removing a well-fixed humeral stem, the length of the procedure, and the need to treat severe bone loss.

No difference in outcome or migration but greater loss of bone mineral density with the Collum Femoris Preserving stem compared with the Corail stem: a randomized controlled trial with five-year follow-up.

AIMS: The aim of this study was to compare the mid-term patient-reported outcome, bone remodelling, and migration of a short stem (Collum Femoris Preserving; CFP) with a conventional uncemented stem (Corail). METHODS: Of 81 patients who were initially enrolled, 71 were available at five years' follow-up. The outcomes at two years have previously been reported. The primary outcome measure was the clinical result assessed using the Oxford Hip Score (OHS). Secondary outcomes were the migration of the stem, measured using radiostereometric analysis (RSA), change of bone mineral density (BMD) around the stem, the development of radiolucent lines, and additional patient-reported outcome measures (PROMs). RESULTS: There were no statistically significant differences between the groups regarding PROMs (median OHS (CFP 45 (interquartile range (IQR) 35 to 48); Corail 45 (IQR 40 to 48); p = 0.568). RSA showed stable stems in both groups, with little or no further subsidence between two and five years. Resorption of the femoral neck was evident in nine patients in the CFP group and in none of the 15 Corail stems with a collar that could be studied. Dual X-ray absorbiometry showed a significantly higher loss of BMD in the proximal Gruen zones in the CFP group (mean changes in BMD: Gruen zone 1, CFP -9.5 (95% confidence interval (CI) -14.8 to -4.2), Corail 1.0 (95% CI 3.4 to 5.4); Gruen zone 7, CFP -23.0 (95% CI -29.4 to -16.6), Corail -7.2 (95% CI -15.9 to 1.4). Two CFP stems were revised before two years' follow-up due to loosening, and one Corail stem was revised after two years due to chronic infection. CONCLUSION: The CFP stem has a similar clinical outcome and subsidence pattern when compared with the Corail stem. More pronounced proximal stress-shielding was seen with the CFP stem, suggesting diaphyseal fixation, and questioning its femoral neck-sparing properties in the long term. Cite this article: Bone Joint J 2022;104-B(5):581-588.

Bone Preservation in Total Hip Arthroplasty.

BACKGROUND: Preserving bone stock in younger and more active patients after total hip arthroplasty (THA) is important for future revision. Newer prosthesis designs, including short femoral stems and isoelastic acetabular cups, are likely to preserve more bone stock. However, long-term follow-up studies on bone remodeling after short-stem THA with an isoelastic monoblock acetabular cup are few. Therefore, we evaluated bone preservation after THA using these prostheses at a 5-year follow-up. METHODS: This prospective observational study is a 5-year follow-up of our previously reported 2-year observational study on the same cohort of patients. We included 45 patients with primary osteoarthritis treated with a calcar-guided femoral short-stem prosthesis and a monoblock press-fit acetabular cup. We evaluated bone mineral density (BMD) around the prostheses using dual-energy X-ray absorptiometry and reported functional outcomes preoperatively and at 3, 12, 24, and 60 months postoperatively. All complications were recorded. RESULTS: At the final follow-up, the BMD was comparable with that at 24 months in Gruen zones 3, 4, 5, 6, and 7, whereas it significantly differed in Gruen zones 1 (P < .0001) and 2 (P < .004). On the acetabular side, the BMD leveled off similarly in all DeLee and Charnley zones between 24 and 60 months (P > .05). Moreover, all measured clinical outcomes significantly improved (P < .001). One perioperative dislocation was reported. CONCLUSION: Patients undergoing THA with a calcar-guided femoral short-stem prosthesis and a monoblock acetabular cup can expect preservation of bone stock over a longer follow-up with excellent clinical outcomes and few complications.

Innovative Design Methodology for Patient-Specific Short Femoral Stems.

The biomechanical performance of hip prostheses is often suboptimal, which leads to problems such as strain shielding, bone resorption and implant loosening, affecting the long-term viability of these implants for articular repair. Different studies have highlighted the interest of short stems for preserving bone stock and minimizing shielding, hence providing an alternative to conventional hip prostheses with long stems. Such short stems are especially valuable for younger patients, as they may require additional surgical interventions and replacements in the future, for which the preservation of bone stock is fundamental. Arguably, enhanced results may be achieved by combining the benefits of short stems with the possibilities of personalization, which are now empowered by a wise combination of medical images, computer-aided design and engineering resources and automated manufacturing tools. In this study, an innovative design methodology for custom-made short femoral stems is presented. The design process is enhanced through a novel app employing elliptical adjustment for the quasi-automated CAD modeling of personalized short femoral stems. The proposed methodology is validated by completely developing two personalized short femoral stems, which are evaluated by combining in silico studies (finite element method (FEM) simulations), for quantifying their biomechanical performance, and rapid prototyping, for evaluating implantability.

Femoral antetorsion after calcar-guided short-stem total hip arthroplasty: A cadaver study.

Calcar-guided short stems in total hip arthroplasty (THA) permit surgeons to successfully reconstruct postoperative femoroacetabular offset, accurately restore leg length, and adequately re-establish a wide range of caput-collum-diaphyseal angles. However, their effect on femoral antetorsion is less known. Indeed, controlling antetorsion of the femoral stem can be challenging because of the differences in individual femoral geometry and curvature. Therefore, we investigated if calcar-guided short-stem THA alters femoral antetorsion and compared it with conventional-stem THA. Using 12 Thiel-fixed, full-body cadaver specimens from donors without known hip disorders, we compared an uncemented calcar-guided femoral short-stem prosthesis with an uncemented conventional straight-stem prosthesis. In a paired study setup, each specimen received a calcar-guided short stem on one side and a conventional stem on the other. On the acetabular side, all specimens received a press-fit, monobloc acetabular cup. Femoral antetorsion angles were measured using the Waidelich method, and pre- and post-operative angles of both sides were recorded. The mean preoperative femoral antetorsion angles were similar in both groups (24.8° ± 7.5° vs. 23.8° ± 6.1°, p = 0.313). Mean postoperative femoral antetorsion angles were 23.0° ± 5.5° in short-stem and 13.5° ± 7.1° in conventional-stem hips. Short-stem hips had a small but nonsignificant difference in femoral antetorsion angles pre- and post-operatively (1.8° ± 3.2°, p = 0.109), while the difference for conventional-stem hips was much larger and highly significant (10.3° ± 5.8°, p < 0.001). Calcar-guided short-stem THA effectively restores femoral antetorsion. However, how this affects long-term clinical outcomes and complications warrants further exploration.

Short neck-preserving femoral stem for total hip arthroplasty: medium-term results of a 68-case series.

INTRODUCTION: Short stems seem to be a good alternative for young patients as they offer promising results, rapid recovery and preservation of metaphyseal bone stock. This is one of the few studies in the literature to report medium-term clinical-radiological results for short hip stems. MATERIALS AND METHODS: This prospective study evaluated 68 short femoral stems in 63 patients treated with total hip replacement. Clinical, functional and quality-of-life outcomes were measured at 6 and 12 months, and annually thereafter until the end of follow-up. The radiological analysis included measurements of potential leg length discrepancies, stem alignment and signs compatible with stress shielding. RESULTS: Fifty-four males (59 hips) and nine females (9 hips) of an average age of 44.3 years (range, 25-68) were studied. The most common diagnosis was osteoarthritis (51.5%). Mean overall follow-up was 7.8 years (range, 5.8-9.8). The overall survival rate was 97.1% (95% CI 88.7-99.7%). Surgery resulted in an increase of 42.3 ± 1.1 points in the modified Harris Hip Score and 21.9 ± 0.6 points in the Oxford Hip Score (p < 0.001, respectively). Moreover, the pain score as measured on a numerical rating scale (NRS) improved from 95.8 to 36.3. As regards function, an improvement was observed from 3.2 ± 0.8 points to 6.8 ± 1.14 points on the University of California at Los Angeles activity score (p < 0.001, respectively). The radiological analysis showed an absence of radiolucencies or stress-shielding throughout the series. The complications rate at the end of follow-up was 5.7%. CONCLUSIONS: The use of ultra-short cylindrical stems with complete anchorage in the femoral neck was shown to offer promising medium-term results. Such stems appear to be a good option for young patients, who are likely to require several revisions over their lifetime.

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.

Complex Primary Total Hip Arthroplasty: Small Stems for Big Challenges.

Total hip arthroplasty is one of the most successful operations in all of medicine. Femoral deformities from malunion, prior osteotomy, and retained surgical implants all present unique challenges. Corrective osteotomy and hardware removal add significant morbidity to an operation that typically has a fast recovery. Short stems can be used in these cases to spare patients' increased morbidity. We present a case-based illustration and surgical technique for the use of short stems in complex primary total hip arthroplasty with femoral deformity and retained hardware. We discuss how these implants can spare significant morbidity, show radiographic examples of their use, and present short-term outcomes.

Ceramic-on-metal bearing in short stem total hip arthroplasty: ions, functional and radiographic evaluation at mid-term follow-up.

INTRODUCTION: The aim of this study is to evaluate clinical, radiographic and laboratory results of ceramic-on-metal (CoM) (hybrid hard bearing) in total hip arthroplasty (THA), associated with a short stem implant. METHODS: From a cohort of 37 patients suffering from primary or secondary hip osteoarthritis who underwent THA using CoM bearing, 19 were suitable for this study. All procedures were performed by the same surgeon using a posterior-lateral approach. All patients were compared clinically using the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analogue scale (VAS), 12-item Short Form Health Survey (SF12F/M), and radiographically (offset, CD angle, limb length discrepancy, cup inclination and anteversion, subsidence, osseointegration, heterotopic ossification). Blood samples were collected in order to evaluate chromium (Cr) and cobalt (Co) ions level. Radiographic evaluations were carried out by 3 different blinded surgeons. A statistical analysis was performed. RESULTS: At a mean follow-up of 97 (73-125) months all implanted stems were well-positioned and osseointegrated. Clear improvements were observed for clinical scores comparing preoperative and postoperative values. Radiographic evaluation showed a good ability to restore proper articular geometry. Cr ion analysis revealed values below the safety threshold except for 1 case. Serum levels of Co were below the threshold in all patients. There was a statistically significant correlation only between Cr metal ions and length of follow-up. CONCLUSIONS: CoM bearing has proven to be reliable and safe at a mean 8-year follow-up for patients in whom the components were correctly implanted. The rise of blood metal ions was minimal and involved neither systemic or local toxicity nor influenced clinical results.

Reemplazo de cadera en pacientes jóvenes: Experiencia con vástago corto preservador de cuello femoral / Hip replacement in young patients: Experience with a femoral neck preserving short stem

Introduccion La tendencia creciente de uso de implantes no cementados y el desarrollo de tecnologías que buscan restablecer la anatomía y función articular con una mayor preservación ósea, ha incrementado el uso de vástagos cortos en el remplazo total de cadera (RTC). El objetivo de este estudio es describir resultados funcionales, restauración radiológica de la anatomía, tasa de complicaciones y reintervención de pacientes sometidos a RTC usando vástagos femorales cortos de fijación cervico metafisiaria con apoyo en cortical lateral. Materiales y Métodos Estudio descriptivo prospectivo, donde se incluyeron 45 caderas en pacientes con artrosis de cadera de cualquier etiología. El seguimiento fue de 18 meses. Las variables de desenlace evaluadas fueron: 1. Integración del implante, 2. Complicaciones dependientes del implante femoral, 3. Subsidencia y 4. Reintervención. Se evaluó adicionalmente el resultado funcional con escala WOMAC. Resultados Durante el periodo comprendido entre diciembre de 2011 a julio 2017, encontramos una mejoría en estado funcional en el 97% (n:44) de los pacientes, no hubo reintervenciones. Discusión En el 100% de los casos se encontró osteointegración del implante y los resultados son comparables con los reportes de la literatura. Consideramos que el uso de vástagos cortos en el Reemplazo total de Cadera es un procedimiento seguro, con buenos resultados, teniendo la ventaja de una adecuada integración ósea del implante y garantizar un mejor stock óseo en una próxima cirugía.

Background The growing trend in the use of non-cemented implants and the development of technologies that attempt to restore the anatomy and joint function with greater bone preservation has increased the use of short stems in the total hip replacement (THR). The objective of this study is to describe functional results, radiological restoration of the anatomy, complication and revision rate of patients undergoing THR using short femoral stems with metaphyseal cervical fixation with lateral cortical support. Materials and Methods A prospective descriptive study was performed that included 45 hips of patients with hip osteoarthritis of any origin. The follow-up was 18 months. The outcome variables evaluated were: 1. Integration of the implant, 2. Complications dependent on the femoral implant, 3. Subsidence, and 4. Re-intervention. The functional result was additionally evaluated using the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Results During the period from December 2011 to July 2017, an improvement was observed in functional status in 97% (n: 44) of patients, with no reoperations. Discussion Bone integration of the implant was observed in 100% of the cases, making the results comparable with the reports in the literature. It is believed that the use of short stems in total hip replacement is a safe procedure, with good outcomes. It also has the advantage of an adequate bone integration of the implant, and guaranteeing a better bone stock in the next surgery.

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

Over the last two decades, several conservative femoral prostheses have been designed. The goals of conservative stems include: the spearing of the trochanteric bone stock; a more physiological loading in the proximal femur reducing the risk of stress shielding; and to avoid a long stem into the diaphysis preventing impingement with the femoral cortex and thigh pain.All stems designed to be less invasive than conventional uncemented stems are commonly named 'short stems'. However, this term is misleading because it refers to a heterogeneous group of stems deeply different in terms of design, biomechanics and bearing. In the short-term follow-up, all conservative stems provided excellent survivorship. However, variable rates of complications were reported, including stem malalignment, incorrect stem sizing and intra-operative fracture.Radiostereometric analysis (RSA) studies demonstrated that some conservative stems were affected by an early slight migration and rotation within the first months after surgery, followed by a secondary stable fixation. Dual-energy x-ray absorptiometry (DEXA) studies demonstrated an implant-specific pattern of bone remodelling.Although the vast majority of stems demonstrated a good osseointegration, some prostheses transferred loads particularly to the lateral and distal-medial regions, favouring proximal stress shielding and bone atrophy in the great trochanter and calcar regions. Cite this article: EFORT Open Rev 2018;3:149-159. DOI: 10.1302/2058-5241.3.170052.

Stemless hip arthroplasty versus traditional implants: a comparative observational study at 30 months follow-up.

INTRODUCTION:: The aim of this retrospective case-control study is to evaluate clinical and radiographic results of short stems compared with traditional hip prostheses. METHODS:: 46 short stems (SS) and 50 traditional stems (TS) were selected. All the stems were implanted by the same surgeon using posterior approach because of primary osteoarthritis, post-traumatic osteoarthritis and avascular necrosis. All the patients were compared clinically by Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analogue scale (VAS), 12-item Short Form Health Survey (SF-12F/M) and radiographically (offset, CD angle, limb length discrepancy, cup inclination, subsidence, osseointegration, heterotopic ossification). Radiographic evaluations were carried out by 3 different blinded surgeons. A statistical analysis was performed (chi-square, t-test, Mann-Whitney). RESULTS:: At a mean follow-up of 30 months all the implanted stems were well-positioned and osseointegrated. In both groups there was a marked improvement in pain ( p < 0.001) with a statistically significant advantage in the SS group for WOMAC (90.8 vs. 87.5; p = 0.02) and in part for HHS (93 vs. 91.7; p = 0.18). The radiographic evaluations, with high concordance correlation between the 3 blinded surgeons (ICC consistently >0.80), showed no significant differences in the restoration of the articular geometry, with a reduction of cortical hypertrophy (2% SS vs. 7% TS) and periprosthetic stress-shielding ( p < 0.05) in the SS group. On the other hand, SS were more related to limb length discrepancy (61% vs. 33%; p < 0.05). No major complications were recorded in the 2 groups. CONCLUSION:: Short stems were shown to be comparable or better than traditional implants at short-term follow-up.

Short stem total hip arthroplasty for osteonecrosis of the femoral head in patients 60 years or younger: a 3- to 10-year follow-up study.

BACKGROUND: In young patients with osteonecrosis of the femoral head (ONFH), short-stem total hip arthroplasty (THA) could allow a potential advantage in preserving metaphyseal bone-stock, when revision surgery might become necessary. However, only a few studies have evaluated the outcome of short-stem THAs in ONFH. We reviewed the prospectively collected data of a cementless partial neck-retaining short-stem with ceramic-on-ceramic bearings in ONFH patients. METHODS: Thirty patients (37 hips) younger than 60 years (mean age at surgery, 51.5 years) underwent THA with the NANOS® stem (Smith and Nephew, Marl, Germany) from January 2006 to December 2012. All patients received a 32-mm or 36 mm ceramic femoral head. Harris hip score, WOMAC and UCLA activity score were recorded. Postoperative radiographs were evaluated for bone-implant fixation and osteolysis. Further analysis correlated clinical findings with implants characteristics and patient demographics at mean 5.6 years' follow-up (range, 3-10 years). RESULTS: The clinical and functional results improved significantly (p < 0.001). At latest follow-up, mean HHS, WOMAC, and UCLA activity scores were 90 (range, 71-100), 94 (range, 76-100), and 6.3 (range, 4-10) points, respectively. The diameter of the femoral head did not influence the clinical outcome (p = 0.661). All hips showed bone ingrowth fixation of the acetabular and femoral components. No patients showed osteolysis. No revision for any reason was performed during the study period. CONCLUSIONS: The excellent clinical results and fixation pattern at mean 5.6 years' follow-up reveal this implant as a reliable option in advanced stage of ONFH either. Further investigations are crucial to determine the long-term durability and to assess whether the association of ceramic-on-ceramic bearings, can be useful to achieve longer survivorship and lower complications rates. TRIAL REGISTRATION: Registry number: ISRCTN 91336248 ; date of registration: 04/07/2017.

Conservative treatment of periprosthetic femur fractures around metaphyseal short stems - A feasible option?

Periprosthetic femoral fractures are rare but significant events following total hip replacement. Metaphyseal short stems have recently been popularized as a bone preserving alternative to conventional uncemented total hip replacement. We present two periprosthetic femur fractures which occurred around two different metaphyseal uncemented stem designs. Successful conservative treatment was possible in both cases achieving bony union and excellent clinical results.

Preservación ósea femoral con tallos cortos de fijación cervicometafisaria. Estudio radiográfico comparativo con tallos no cementados de fijación metafisaria / Femoral bone presevation using short stems with metaphyseal fixation

Introducción: Los tallos no cementados recubiertos con hidroxiapatita de fijación metafisaria han logrado excelentes resultados a largo plazo. La segunda generación de tallos cortos de fijación cervicometafisaria ha surgido a principios de la década de 1990, con el objetivo de preservar capital óseo femoral. Sin embargo, la preservación ósea femoral teóricamente propuesta no ha sido comprobada. El objetivo de este trabajo es determinar radiográficamente la preservación del capital óseo femoral cuando se utilizó un tallo corto de fijación cervicometafisaria, comparando las radiografías posoperatorias con la programación del tallo que se debería haber utilizado en caso de ser un diseño convencional con fijación metafisaria. Materiales y Métodos: Los primeros 50 tallos cortos de fijación cervicometafisaria (MiniHip TM, Corin, Cirencester, Reino Unido) fueron analizados por dos observadores independientes, con radiografías de frente, en cuanto a nivel de resección cervical y longitud del tallo, comparándolos con las filminas de un tallo convencional de fijación metafisodiafisaria (MetaFix TM, Corin, Cirencester, Reino Unido). Resultados: Según el análisis radiográfico, los tallos cortos de fijación cervicometafisaria ocuparon una longitud femoral promedio de 79 mm (rango 68-102). Los tallos convencionales de fijación metafisaria hubiesen ocupado, en promedio, 73 mm más que los tallos cortos (rango 47-94). Esta distribución se observó en el corte de cuello (promedio 10 mm más distal) y en la longitud del implante (promedio 66 mm mayor longitud) (p <0,001). Esta diferencia permite preservar un 42% el capital óseo femoral. Conclusión: La preservación ósea relacionada con el uso de tallos cortos de fijación cervicometafisaria podría traer beneficios a largo plazo en pacientes jóvenes con alta demanda funcional.

Background: Uncemented hydroxyapatite-coated stems with methaphyseal fixation have demonstrated excellent long-term results. Second generation of short stems has been developed in the 90’s with the purpose to preserve femoral bone at the femoral neck and diaphysis. However, the amount of bone that would be theoretically saved has not been well-established. To radiographically determine femoral bone preservation in a series of patients operated on with a short, neck preserving stem, we compared these results with the length of a templated conventional length, uncemented hydroxyapatite-coated stem. Methods: The first 50 short hydroxyapatite-coated uncemented stems (MiniHip TM, Corin, Cirencester, UK) were radiographically analyzed by two independent observers measuring the level of neck cut and the stem length. Then, these results were compared with the level of neck cut and stem length when a conventional, metaphysodiaphyseal stem (MetaFix TM, Corin, Cirencester, UK) was implanted using templates. Results: According to the radiographic results, short stems measured an average length of 79 mm (range 68-102). Conventional stems would have required 78 mm (range 47-94) more bone for fixation than short stems. This difference was observed in the neck cut (average 10 mm more distal with a conventional stems), as well as in the diaphysis (average 66 mm more distal with a conventional stems) (p <0.001). Conclusion: Femoral bone preservation may be related to long-term benefits especially in young patients.

The short stem: promises and pitfalls.

Conventional uncemented femoral implants provide dependable long-term fixation in patients with a wide range of functional requirements. Yet challenges associated with proximal-distal femoral dimensional mismatch, preservation of bone stock, and minimally invasive approaches have led to exploration into alternative implant designs. Short stem designs focusing on a stable metaphyseal fit have emerged to address these issues in total hip replacement (THR). Uncemented metaphyseal-engaging short stem implants are stable and are associated with proximal bone remodeling closer to the metaphysis when compared with conventional stems and they also have comparable clinical performances. Short stem metaphyseal-engaging implants can meet the goals of a successful THR, including tolerating a high level of patient function, as well as durable fixation.