Short stems in total hip arthroplasty are increasingly being established and offer several advantages in terms of minimal invasiveness and bone preservation compared to standard implants. The rounded design and shorter stem length facilitate better adaptation to natural anatomy, at the same time also posing specific risks and complications. When transitioning to short stems, a learning curve must be considered. Careful patient selection and preoperative planning are crucial, and intraoperative imaging is recommended. The most common implant-specific complications include insufficient osseointegration, leading to subsidence and aseptic loosening, as well as periprosthetic fractures. The risk instability and dislocations as well as periprosthetic infections can potentially be reduced with short stems. This article discusses the frequency, causes, and treatment options for these types of complications and highlights current evidence-based treatment approaches.

Aims Limited implant survival due to aseptic cup loosening is most commonly responsible for revision total hip arthroplasty (THA). Advances in implant designs and materials have been crucial in addressing those challenges. Vitamin E-infused highly cross-linked polyethylene (VEPE) promises strong wear resistance, high oxidative stability, and superior mechanical strength. Although VEPE monoblock cups have shown good mid-term performance and excellent wear patterns, long-term results remain unclear. This study evaluated migration and wear patterns and clinical and radiological outcomes at a minimum of ten years' follow-up. Methods This prospective observational study investigated 101 cases of primary THA over a mean duration of 129 months (120 to 149). At last follow-up, 57 cases with complete clinical and radiological outcomes were evaluated. In all cases, the acetabular component comprised an uncemented titanium particle-coated VEPE monoblock cup. Patients were assessed clinically and radiologically using the Harris Hip Score, visual analogue scale (pain and satisfaction), and an anteroposterior radiograph. Cup migration and polyethylene wear were measured using Einzel-Bild-R & ouml;ntgen-Analyze software. All complications and associated treatments were documented until final follow-up. Results Clinical assessment showed persistent major improvement in all scores. On radiological assessment, only one case showed a lucent line (without symptoms). At last follow-up, wear and migration were below the critical thresholds. No cup-related revisions were needed, indicating an outstanding survival rate of 100%. Conclusion Isoelastic VEPE cups offer high success rates and may prevent osteolysis, aseptic loosening, and the need for revision surgeries in the long term. However, longer follow-up is needed to validate our findings and confirm the advantages offered by this cup.

The indications for cementless short-stem total hip arthroplasty (THA) have been expanded due to encouraging results. However, no evidence in cases of femoral neck fractures (FNFs) is available. We aimed to prospectively obtain data on the safety and the clinical outcomes of a cementless calcar-guided short stem in patients with FNFs. We conducted a prospective observational study of 68 patients diagnosed with FNFs who underwent short-stem THA between 2016 and 2019 with a calcar-guided stem. Complications during follow-up leading to revision were documented, and patient reported outcome measurements recorded. Stem migration was analyzed using the Einzel-Bild-Röntgen-Analysis Femoral Component Analysis software. The mean follow-up was 33.8 ± 14.8 months. The patient mortality at last follow-up was 10.6

The described procedure has proven successful in clinical practice in the three author affiliations in a total of 14 cases. In 3 (21.4%) cases, despite the use of the extraction chisel system, an additional transfemoral approach or fenestration had to be performed to remove the short stem. Primary straight stems were used in over half of the cases (57.8%) as revision implants, whereas in 4 cases (36.4%) a cementless short stem could again be used.

Introduction Bone preservation and long-term survival are the main challenges in cementless total hip arthroplasty (THA). A good bone stock is especially important for adequate anchorage of the cup in revision cases. However, the optimal acetabular cup design for preserving good bone stock is still unclear. We aimed to compare clinical outcome, radiological alterations, migration, and wear at mid-term for two different cup types. Materials and methods This retrospective matched-pair study was performed using the data for 98 THA cases treated with a monoblock cup composed of vitamin E-blended highly cross-linked polyethylene (VEPE; monoblock group) or a modular cup composed of a highly cross-linked polyethylene (HXLPE) without an antioxidant (modular group). Clinical results were evaluated using the Harris Hip Score (HHS). The obtained radiographs were analyzed for radiological alterations, migration, and wear using Einzel-Bild-Röntgen-Analyse (EBRA) software. Results The mean follow-up duration was 73.2 ± 19.2 months (range: 32–108 months) and 60.5 ± 12.2 months (range: 20–84 months) in the monoblock and modular groups, respectively. HHS improved to 95.7 points in the monoblock group and 97.6 points in the modular group, without significant differences ( p = 0.425). EBRA measurements were obtained in all cases. Acetabular bone alterations were not detected on radiological assessments. Mean cup migration was 1.67 ± 0.92 mm (range: 0.46–3.94 mm) and 1.24 ± 0.87 mm (range: 0.22–3.62 mm) in the monoblock and modular groups. The mean wear rate was 0.21 ± 0.18 mm (range: 0.00–0.70 mm) and 0.20 ± 0.13 mm (range: 0.00–0.50 mm) in the monoblock and modular groups. Both migration and wear pattern showed no significant differences ( p = 0.741 and 0.243). None of the cases required revision surgery, yielding an implant survival rate of 100% in both groups. Conclusion The isoelastic press-fit monoblock VEPE cup and modular metal-back HXLPE cup showed equivalent mid-term wear and cup migration. Long-term studies are required to determine the effects of modularity, isoelasticity, and polyethylene stabilization with vitamin E on cup loosening and survival rates.

In recent decades, a large number of cementless short stems have been introduced to the market. The concept aims at saving soft tissue using minimally invasive surgery and at the same time preserving as much bone as possible. In particular, the latest generation of short stems, which are implanted using a calcar-guided round-the-corner technique, are attracting increasing attention. An individualised resection level allows individual stem alignment and thus an ideal reconstruction of the hip anatomy. The early clinical results of short-stem total hip arthroplasty (THA) are promising and have led to an expansion of the indications and limitations for the use of short stems. In particular, the individual positioning in valgus or varus and the resulting individual metaphyseal or metadiaphyseal anchorage offers various possibilities to reconstruct even abnormal joint morphologies. Consequently, short stems are increasingly used in patients with complex anatomical variations or in cases of osteonecrosis of the femoral head. In some various cases, they can also be used in revision or conversion arthroplasty. In some patients, short stems can also be used after femoral neck fracture. Currently, scientific data on those areas of indication of short-stem THA is scarce.

Zusammenfassung Operationsziel Sichere und knochensparende Extraktion eines fest eingewachsenen kurvierten Kurzschaftes ohne die Notwendigkeit eines transfemoralen Zuganges. Indikationen Revision eines fest eingewachsenen Kurzschaftes beispielsweise bei periprothetischer Infektion oder Malposition. Kontraindikationen Korrekte Platzierung der Konusschablone nicht möglich. Operationstechnik Wahl eines Standardzugangs zum Hüftgelenk. Luxation des Gelenkes. Abschlagen des einliegenden Kopfimplantats. Sorgfältiges Freipräparieren des Konus und der lateralen Schulter. Aufbringen und Befestigen der Konusschablone. Beginn des vorsichtigen Einschlagens der Eröffnungsmeißel, zunächst lateral, anschließend ventral und dorsal über die Führungen der Schablone. Es ist darauf zu achten, dass stets der Schliff vom Implantat weg zeigt. Anschließend Wiederholung des Vorganges mit den Startermeißeln in gleicher Reihenfolge. Entfernung der Schablone. Vorsichtiges Einschlagen der Finalen Meißel in gleicher Reihenfolge. Versuch einer Schaftextraktion mittels Ausschlaginstrumentarium. Fakultativ Wiederholung des Gesamtvorganges. Zur Vermeidung von Frakturen, erst nach Mobilisation des Interfaces lateral, ventral und dorsal, Freilegung des Interfaces auch medial mittels medialer Meißel in der entsprechenden Reihenfolge. Abschließend Schaftextraktion. Weiterbehandlung Mobilisierung und Belastungsaufbau gemäß der gewählten Revisionsimplantate und Verankerungstechnik. Ergebnisse Das beschriebene Vorgehen hat sich in der klinischen Praxis in den 3 Autorenkliniken in insgesamt 14 Fällen bewährt. In 3 (21,4 %) Fällen musste trotz Nutzung des Extraktions-Meißel-Systems zusätzlich ein transfemoraler Zugang bzw. eine Fensterung erfolgen, um das Schaftimplantat zu entfernen. Als Revisionsimplantate wurden in über der Hälfte der Fälle (57,8 %) primäre Geradschäfte verwendet, in 4 Fällen (36,4 %) konnte erneut ein zementfreier Kurzschaft verwendet werden.

ZusammenfassungIn den letzten Jahrzehnten ist eine Vielzahl von zementfreien Kurzschaftprothesen auf den Markt gekommen. Gemeinsam vereinen sie das Ideal der weichteilschonenden und minimalinvasiven Hüftgelenksendoprothetik mit knochensparenden Implantationstechniken. Hervorzuheben ist die neueste Generation von Kurzschaftprothesen, die schenkelhalsteilerhaltend und kalkargeführt in einer Round-the-Corner-Technik implantiert werden. Die patientenadaptierte Resektionsebene ergibt die Möglichkeit für eine variable Positionierung des Implantates und eine optimale Rekonstruktion der individuellen Hüftgeometrie. Die vielversprechende frühe Datenlage in der primären hüftendoprothetischen Versorgung führt zunehmend zu einer Ausweitung der Möglichkeiten und Grenzen des Kurzschaftes. Insbesondere die individuelle Positionierung in Valgus- oder Varusposition und die resultierende individuelle metaphysäre oder metadiaphysäre Verankerung eröffnet zahlreiche Möglichkeiten, auch abweichende anatomische Hüftgelenksvarianten optimal rekonstruieren zu können. Zunehmend finden daher Kurzschaftprothesen auch Einsatz bei Patienten mit komplexen anatomischen Variationen, Anomalien oder auch bei aseptischen Hüftkopfnekrosen. In Einzelfällen werden sie auch in der Revisions- oder Konversionsendoprothetik eingesetzt. In bestimmten Einzelfällen können diese Implantate auch in der Frakturendoprothetik eingesetzt werden. Wissenschaftliche Untersuchungen hierzu stehen gegenwärtig jedoch noch aus.

Abstract Purpose Reoperations for secondary osteoarthritis, osteonecrosis, or hardware failure following failed internal fixation after intertrochanteric fracture (ITF) or femoral neck fracture (FNF) are common. An effective salvage treatment often involves complete removal of the hardware followed by total hip arthroplasty (THA). Almost no data are available regarding conversion to short-stem THA. This study aimed to evaluate clinical and radiological outcomes, potential complications, and the survival rate of short-stem THA following revision surgery. Methods We investigated 27 patients who underwent conversion THA using a calcar-guided short stem. Patient-reported outcome measurements were obtained, including the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index, as well as pain and satisfaction on the visual analogue scale. Radiological follow-up was also performed. Results We identified 18 (66.7%) patients diagnosed with FNF and 9 (33.3%) patients with ITF. Clinical and radiological outcomes were satisfactory at the last follow-up (30.56 ± 11.62 months). One patient required early revision surgery due to dislocation and greater trochanter fracture. At the last follow-up, none of the short stems required revision. No other major complications occurred. Conclusion Given the low rate of complications and 100% survival, our findings indicate that short stems for conversion THA due to failed internal fixation may be considered an option in a properly selected patient population. However, it should not be considered a standard procedure and should only be performed by experienced surgeons.

Introduction Short stems are a bone and soft-tissue preserving alternative to conventional stems. The aim of this multicenter study is to present the mid-term outcomes of a calcar-guided short stem. Materials and methods This is a prospective case series of the first 879 total hip arthroplasties performed on 782 patients across 5 centers using identical calcar-guided short stems. In a mid-term follow-up (6 years), rates and reasons for complications and revisions were documented. The Harris Hip Score (HHS) was obtained; patients reported pain and satisfaction using a visual analog scale. Results A total of 43 patients died in the study cohort for non-related reasons; 26 patients (3.0%) required at least 1 revision after the index procedure. The survival rate for endpoint stem revision at mid-term was 98.4%. The main reasons for stem revision were aseptic loosening and early periprosthetic fractures. Sex had no influence on stem survival. Older patients or those with a high body mass index showed increased risk for stem revision during follow-up. Dorr type A morphology revealed a significantly lower risk of stem revision than Dorr type B or C (p = 0.0465). The HHS, satisfaction, and load pain at mid-term were 96.5 (SD 8.0), 9.7 (SD 0.9), and 0.5 (SD 1.9), respectively. Conclusions This short stem produced highly satisfactory outcomes at mid-term, with 98.4% implant survival for any cause of stem revision and low complication rates. Long-term results are required to further evaluate these promising mid-term results.

A variety of short stems have recently been introduced. The purpose of this study was to evaluate rates and reasons for revision, as well as postoperative short-term radiological and clinical results, after implantation of a short stem of the newest generation in short stem total hip arthroplasty. In this prospective multicenter study, 879 total hip arthroplasties, using the optimys short stem combined with a cementless cup with a mean follow-up time of 27.3 months (standard deviation SD 7.9), and identical postoperative regimens with full weight bearing, were included. Complications and revisions were documented. Pre- and postoperative radiographs were obtained using a standardized technique. Radiographic alterations were analysed. Pre- and postoperatively, Harris hip score (HHS), rest pain, load pain and satisfaction using the visual analogue scale (VAS) were assessed. In 13 cases (1.5 %) stem-related revision surgery was needed, five cases (0.6 %) of these involved treatment for aseptic loosening. In 2.2% of cases, radiolucent lines were observed at the prosthesis bone interface. HHS improved from a mean of 46.7 (SD 15.3) preoperatively to 95.7 (SD 8.7) (p < 0.0001) at last follow-up, with 94.1 % excellent or good results. Patient satisfaction using VAS improved from 2.7 (SD 2.4) to 9.6 (SD 1.1) (p < 0.0001). Rest pain and load pain decreased from 4.5 (SD 2.7) to 0.2 (SD 0.8) (p < 0.0001) and 7.4 (SD 1.9) to 0.5 (SD 1.3) (p < 0.0001), respectively. The investigated meta-diaphyseal anchoring, calcar-guided short stem provides reliable radiological and clinical results in the short-term.

BACKGROUND:One-stage, bilateral, short-stem total hip arthroplasty (1B-ssTHA) represents an alternative to staged, unilateral, short-stem total hip arthroplasty (U-ssTHA); however, the safety and reliability of 1B-ssTHA remain unknown. The objective of the present study was to compare the functional outcomes, complications, and mortality rates between 1B-ssTHA and U-ssTHA at mid-term. METHODS:A retrospective, matched-pair study was performed, including 216 short stems implanted in 162 patients. Among the study population, 54 patients were treated with 1B-ssTHA. Patients were matched by gender, age, body mass index (BMI), and American Society of Anesthesiologists (ASA) classification. A total of 46 full matches could be accomplished. The mean follow-up time for the 1B-ssTHA group was 61.7 months (standard deviation [SD] 6.2 months), compared with was 63.4 months (SD 8.0 months) for the U-ssTHA group. Mortality, complication, and revision rates were documented. For clinical examinations, the visual analogue scale (VAS) was used to evaluate satisfaction, rest pain, and load pain, and the Harris Hip Score (HHS) was determined. RESULTS:No surgery-related deaths were observed. At mid-term, none of the 1B-ssTHA patients required stem revision. The rate of complications for both groups was low. The mean drop in haemoglobin measured in the 1B-ssTHA group was 4.42 mg/dl, compared with 3.18 mg/dl in the U-ssTHA group. The mean HHS in the 1B-ssTHA group was 98.3 points (SD 2.80), whereas, in the U-ssTHA group, the mean HHS was 97.9 points (SD 3.44) (p = 0.478). Satisfaction rates were significantly higher in the 1B-ssTHA group (p = 0.04) than in the U-ssTHA group, whereas no significant differences were found for pain at rest and pain at load (p = 0.56 and p = 0.26, respectively). CONCLUSION:Our findings indicate that 1B-ssTHA is an effective and beneficial procedure for a select population. Mortality, complications, implant survival, and clinical outcomes were comparable to those for a matched group with unilateral osteoarthritis treated with U-ssTHA. However, an increase in blood loss must be acknowledged for the 1B-ssTHA procedure.

CASE:A 76-year-old man presented with periprosthetic tibial plateau fracture (TPF), with a completely loosened tibial component 3 weeks after cementless unicompartmental knee arthroplasty (UKA). Internal fixation by buttress plating was performed, and the tibial component was retained and left in situ primarily as a spacer. Revision was planned after fracture consolidation, but at 3 months, the patient was able to walk without support, without pain, and with full range of motion. At 1 year, he is free of complaints. The initial loosened tibial component reintegrated. CONCLUSION:Internal fixation combined with preserving the loosened tibial component may be a treatment option for TPF involving a cementless UKA.

BACKGROUND:The usage of short stems in primary total hip arthroplasty (THA) has constantly gained popularity over the last decade, however, to date, short stems are not eligible to be used as revision implants. The aim of this study was to retrospectively evaluate the outcome of revision surgery of failed hip resurfacing arthroplasty (HRA) using short-stem THA. METHODS:In a single center, retrospective analysis, 6 consecutive patients who were treated with a calcar-guided short stem after failure of HRA were evaluated. The mean follow-up was 3.25 years (SD 0.45). Patient reported outcome measurements (PROMs) were recorded using the Harris hip score (HHS) and The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The health status was evaluated by the EQ-5D-5L score. Pain and satisfaction were obtained using the visual analogue scale (VAS). Radiographic analysis was performed by evaluating osteolysis, stress shielding, alignement and signs of aseptic loosening. Complications were documented. RESULTS:At last follow-up, clinical outcome was excellent (HHS ≥ 90) in 5 patients and good (HHS = 87) in 1 patient. The mean WOMAC score was 5.73% (SD 3.66%). The mean EQ-5D-5L index was 0.914 (SD 0.07). Pain and satisfaction on VAS was 1.83 (SD 5.18) and 8.67 (SD 0.94), respectively. Radiologically, no signs of subsidence, aseptic loosening, stress shielding and fracture were obvious. No major complications occurred. To date, no further revision surgery was needed. CONCLUSIONS:The outcomes of the present case series propose that HRA can be safely revised using short-stem THA in a selected patient group. Clinical and radiological results are encouraging. Based on the present data, short stems may be considered as a revision implant for failed HRA for experienced surgeons.

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

Background Short stems have constantly gained popularity in primary total hip arthroplasty (THA) over the last decade. Although cementless short stems are not primarily designed to be used as revision implants, there may be certain indications for which downsizing the femoral component in failed conventional THA is potentially advantageous. Methods In this single center retrospective case series, six patients who underwent revision using a calcar-guided short stem after failed THA are presented. The mean follow-up was 3.32 years (SD 0.63 years). The health status was evaluated by the EQ-5D-5L score. Patient reported outcome measurements (PROM) were recorded using the Harris hip score (HHS) and The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Pain and satisfaction were assessed using a visual analogue scale (VAS). Radiographic analysis was performed by evaluating osteolysis, stress shielding, alignment and signs of aseptic loosening. Complications were documented. Results At last follow-up the mean EQ-5D-5L index was 0.851 (SD 0.098). Clinical outcome was excellent (HHS ≥ 90) in 4 patients and moderate (HHS 71 and 79) in 2 patients. The mean WOMAC score was 9.20% (SD 12.61%). Pain and satisfaction on VAS were 1.00 (SD 1.15) and 9.17 (SD 0.37), respectively. No major complications occurred. To date, no further revision surgery was needed. Radiologically, no signs of subsidence, aseptic loosening, stress shielding and fractures were obvious. Conclusion The present case series indicates that in failed conventional THA downsizing may be considered a treatment option, using short stem THA in selected cases.

Purpose In total hip arthroplasty, uncemented short stems have been used more and more frequently in recent years. Especially for short and curved femoral implants, bone-preserving and soft tissue-sparing properties are postulated. However, indication is limited to sufficient bone quality. At present, there are no curved short stems available which are based on cemented fixation. Methods In this in vitro study, primary stability and maximum fracture load of a newly developed cemented short-stem implant was evaluated in comparison to an already well-established cemented conventional straight stem using six pairs of human cadaver femurs with minor bone quality. Primary stability, including reversible micromotion and irreversible migration, was assessed in a dynamic material-testing machine. Furthermore, a subsequent load-to-failure test revealed the periprosthetic fracture characteristics. Results Reversible and irreversible micromotions showed no statistical difference between the two investigated stems. All short stems fractured under maximum load according to Vancouver type B3, whereas 4 out of 6 conventional stems suffered a periprosthetic fracture according to Vancouver type C. Mean fracture load of the short stems was 3062 N versus 3160 N for the conventional stems (p = 0.84). Conclusion Primary stability of the cemented short stem was not negatively influenced compared to the cemented conventional stem and no significant difference in fracture load was observed. However, a clear difference in the fracture pattern has been identified.

Introduction: Undersizing is 1 of the main reasons for early implant failure. Adequate sizing in short-stem total hip arthroplasty can be challenging and, so far, lacks key decision criteria. Methods: We included 191 calcar-guided short stems. All patients underwent standardised digital anteroposterior imaging pre- and post-surgery and during follow-up. Preoperative planning was performed digitally. Planned stem sizes were retrospectively assessed and compared with the implanted sizes. Additionally, adequate sizing was analysed by determining whether the stem made intraoperative contact with the lateral distal femoral cortex. Implant migration was assessed by Ein-Bild-Roentgen-Analysis Femoral-Component-Analysis 5 years after surgery. Influence of different Dorr types and postoperative centrum-collum-diaphyseal angle (CCD) categories on lateral femoral cortical contact were analysed. Additionally, the Harris Hip Score (HHS) was assessed at final follow-up. Stem-revision rate was documented. Results: Implanted stems were at least 2 sizes smaller than those at the preoperative planning in 49 (25.7%) cases. The stem made contact with the lateral distal femoral cortex in only 130 hips (68.1%). Mean subsidence was significantly higher in the no-contact group (2.07 mm, range −7.7 to 1.7) than in the contact group (1.23 mm, range −4.5 to 1.8) at the final follow-up (p = 0.0018). Stems at least 2 sizes smaller than those at preoperative planning showed a significantly higher prevalence of non-contact (46.9% vs. 26.8%) (p = 0.009). Those undersized stems were more likely found in varus hips. No influence of the Dorr classification and the different CCD categories on the probability of achieving sufficient cortical contact was found. HHS showed no intergroup differences. Conclusions: Stems that did not make intraoperative contact with the lateral femoral cortex showed significantly increased axial migration at mid-term follow-up. Thus, the investigated criteria regarding the definition of undersizing in short-stem THA should be acknowledged. No obvious mid-term consequences were noted regarding revision rate. Long-term results are mandatory.

External calibration markers (ECM) are the standard of care for digital templating in joint replacements. Spherical mono markers are known to be unreliable. Fixed calibration factors (FCF) can reduce the overall error by placement of markers, but do not address individual patient anatomy. Dual scale calibration marker (DSCM) methods were developed to improve precision of calibration but require two markers. This prospective observational study is the first to analyse the application of a dual scale type single marker (DSSM) method in supine radiographs. One hundred patients with unilateral total hip arthroplasty (THA) underwent anterior-posterior pelvis X-ray with ECM and DSSM. The femoral THA head components were used as internal reference (ICM). An empirical fixed calibration factor (FCF; 120%) was used as comparator. Absolute differences of ICM and both ECM and DSSM were calculated. Absolute relative deviations (ARD) were calculated. Mean absolute calibration factor differences of ECM, FCF and DSSM from ICM were 0.105 (0.002–0.182), 0.016 (0.082–0.013) and 0.011 (0.056–0.009), respectively. ARD differences between ECM and DSSM as well as FCF and DSSM were significant (p < 0.001). The DSSM method showed superior results over ECM and FCF to predict the optimal calibration factor in supine radiographs. The novel DSSM method could be used to improve digital templating in supine radiographs without need for additional markers.

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