Radiological identification of Zweymüller-type femoral stem prosthesis in revision cases

Introduction

Since 1979 the number of patients treated with femoral stems has continued to grow, as well as the number of stems with features similar to the Zweymüller prosthesis produced by different companies. Identification can be problematic in case requiring revision. In the present paper, we present an overview of morphometric differences between the different stem designs, which can be useful for radiologic identification in revision cases.

Methods

By doing some research on the Internet of specialized sites and worldwide literature, we searched for all femoral stems agreeing with Zweymüller principles (cementless, straight, tapered, rectangular cross-sectioned femoral stems).

Results

We found 26 different stems from different companies producing or having produced in the past the Zweymüller-type femoral stems for hip prosthesis.

Discussion

Accurate preoperative identification of the Zweymüller femoral stem type may be of critical importance to eventual outcomes following revision surgery. Each manufacturer has different instruments specific to the removal of their primary implants, and ensuring they are available can simplify the revision procedure significantly. Exact pre-operative planning is also necessary for selecting the correct ball head in cases where a stem is well-fixed and can be left in situ. The commonly used notation "Eurocone 12/14" provides no information about the actual taper angle. Whenever the stem is left in situ, the exact specifications of the taper must therefore be obtained from the manufacturer in order to use a metal sleeve that precisely fits it and the ball head. Failure to do so may result in severe complications, such as metallosis. In cases where it is not possible to identify the taper angle, the surgeon may even consider removal of the stem, though this significantly increases the surgical procedure's invasiveness. Only a single, uniform standard taper, such as that offered until 1994 by CeramTec, can solve these issues in the future.

Conclusion

The survival rate of the Zweymüller stems after ten years was 96 % and the complication rate was very low. Pre-operative identification of the femoral implant is of considerable importance for planning and correctly implementing revision procedures.

     

The Baba classification focused on implant designs is useful in setting the therapeutic strategy for interprosthetic femoral fracture

Purpose

The purpose of this study was to investigate the clinical outcomes of femoral fracture with implants on the proximal and distal sides to verify whether actual fracture morphologies follow the fracture types of Baba classification focusing on implant designs useful for periprosthetic femoral fracture.

Methods

Prosthesis was present in 85 with periprosthetic femoral fractures. Excluding 73 patients with fracture around the femoral stem or fracture of the TKA femoral component alone, 12 patients with 14 legs with both implants were investigated. All patients were radiographically assessed for implant stability according to the Baba classification. For clinical evaluation, intra- and postoperative complications, the operation time, and intra-operative blood loss were investigated.

Results

The Baba classification fracture type showed the implant as unstable and stable types in 3 and 11 legs, respectively. The consistency rate between the Baba classification-based judgment of plain radiograms acquired at the time of injury and actual surgical findings was 100%. As a result of treatment according to the Baba classification, bone union was achieved in all patients. There were no intra- or postoperative complications.

Conclusions

Applying the Baba classification, implant stability could be sufficiently evaluated in not only periprosthetic femoral fractures following hip arthroplasty, but also interprosthetic femoral fractures, thereby verifying its usefulness in setting the treatment strategy.

     

Cementless total hip arthroplasty for patients previously treated with femoral osteotomy for hip dysplasia: the incidence of periprosthetic fracture

Purpose

Femur deformities can make stem fixation difficult in total hip arthroplasty (THA). We report the clinical results of cementless THA using a press-fit stem in patients who had previously undergone femoral osteotomy for hip dysplasia.

Methods

The subjects included 66 hips in 64 patients, with the mean follow-up period of 7.3 years. THA was performed at a mean period of 17.1 years after intertrochanteric femoral osteotomy. Valgus osteotomy was performed in 42 hips, and varus osteotomy in 24. Clinical results were evaluated by using the Merle d’Aubigne-Postel score. Implant survival was determined with revision as the end point, and any related complications were investigated.

Results

The Merle d’Aubigne-Postel score improved from 9.4 to 16.1 at the final follow-up, without any implant loosening. However, periprosthetic femoral fractures were observed in four hips (6.0 %), one intra-operatively and three within three weeks after THA. Among these cases, three hips previously had varus osteotomy (12.5 %) and one hip had valgus osteotomy (2.3 %). Two hips were revised with full porous stems and circumferential wiring. The five and ten year cumulative survivorship rates were 97 % (range, 88.8–99.3 %) and 97 % (88.8–99.3 %), respectively.

Conclusions

Although the use of a press-fit cementless stem yielded acceptable results in most of the patients, perioperative femoral fracture was a major complication especially in the patients previously treated with intertrochanteric varus osteotomy. Careful planning and implant selection could be emphasized for these cases.

     

Clinical significance of corrosion of cemented femoral stems in metal-on-metal hips: a retrieval study

Purpose

The clinical significance of corrosion of cemented femoral stems is unclear. The purpose of this retrieval study was to: (1) report on corrosion at the stem-cement interface and (2) correlate these findings with clinical data.

Methods

We analysed cemented stems (n?=?36) composed of cobalt-chromium (CoCr) and stainless steel (SS) in a series of revised metal-on-metal hips. We performed detailed inspection of each stem to assess the severity of corrosion at the stem-cement interface using a scale of 1 (low) to 5 (severe). We assessed the severity of corrosion at each stem trunnion and measured wear rates at the head taper and bearing surfaces. We used non-parametric tests to determine the significance of differences between the CoCr and SS stems in relation to: (1) pre-revision whole blood Co and Cr metal ion levels, (2) trunnion corrosion, (3) bearing surface wear and (4) taper material loss.

Results

The corrosion scores of CoCr stems were significantly greater than SS stems (p?<?0.01). Virtually all stem trunnions in both alloy groups had minimal evidence of corrosion. The median pre-revision Co levels of implants with CoCr stems were significantly greater than the SS stems (p?<?0.01). There was no significant difference in relation to pre-revision Cr levels (p?=?0.521). There was no significant difference between the two stem types in relation to bearing wear (p?=?0.926) or taper wear (p?=?0.148).

Conclusions

Severe corrosion of cemented femoral stems is a common finding at our retrieval centre; surgeons should consider corrosion of CoCr stems as a potential source of metal ions when revising a hip.

     

No difference in flexion power despite iliopsoas fatty degeneration in healed hip fractures with large lesser trochanter displacement

Objective

To evaluate iliopsoas atrophy and loss of function after displaced lesser trochanter fracture of the hip.

Design

Cohort study.

Setting

District hospital.

Patients

Twenty consecutive patients with pertrochanteric fracture and displacement of the lesser trochanter of?>?20 mm.

Intervention

Fracture fixation with either an intramedullary nail or a plate.

Outcome measurements

Clinical scores (Harris hip, WOMAC), hip flexion strength measurements, and magnetic resonance imaging findings.

Results

Compared with the contralateral non-operated side, the affected side showed no difference in hip flexion force in the supine upright neutral position and at 30° of flexion (205.4 N vs 221.7 N and 178.9 N vs. 192.1 N at 0° and 30° flexion, respectively). However, the affected side showed a significantly greater degree of fatty infiltration compared with the contralateral side (global fatty degeneration index 1.085 vs 0.784), predominantly within the psoas and iliacus muscles.

Conclusion

Severe displacement of the lesser trochanter (>?20 mm) in pertrochanteric fractures did not reduce hip flexion strength compared with the contralateral side. Displacement of the lesser trochanter in such cases can lead to fatty infiltration of the iliopsoas muscle unit. The amount of displacement of the lesser trochanter did not affect the degree of fatty infiltration.

Level of evidence

II.

     

Vancouver B2 periprosthetic femoral fractures: a comparative study of stem revision versus internal fixation with plate

Introduction

The aim is to compare stem revision versus internal fixation with plate in the treatment of Vancouver B2 periprosthetic femoral fractures.

Materials and methods

This is a retrospective review of 34 consecutive patients admitted from June 1998 to May 2017. One patient was treated conservatively, 11 with stem revision (group 1), 20 with plate, screws and cerclage (group 2), one patient with cerclage alone and another by Girdlestone procedure. We assessed surgical complications, mortality within 1 year, functional outcome with Harris Hip Score and radiographic outcome with Beals and Tower’s criteria.

Results

At an average follow-up of 30.1 months in group 1, we had 36.4% of patients with complications, HHS of 66.8, radiographic outcome “excellent-good” in 91% of cases. In group 2 we had 25% of patients with complications, HHS of 71.8, radiographic outcome “excellent-good” in 80% of cases. There were no significant differences in 1-year mortality between the two groups. In group 2, the best outcomes were obtained in uncemented straight stems with Johansson type 1 fracture and in cemented polished stems with stem detachment from the cement–bone complex. Whatever treatment was adopted, there was an overall worsening in quality of life.

Conclusions

Stem revision remains the treatment of choice in Vancouver B2 fractures, but, in selected cases, internal fixation with plate, screws and cerclage can be a viable alternative option.

     

Gelenkerhaltende Versorgung der medialen Schenkelhalsfraktur mit einem winkelstabilen Implantat

Objective

Operative stabilization is recommended even for non-displaced or only slightly displaced femoral neck fractures. In addition to the known osteosynthetic procedures, an angular stabile implant system (Targon® FN) has been established since 2006 for treatment of such fractures.

Indications

Displaced femoral neck fractures (Garden III and IV) and non-displaced fractures (Garden I and II).

Contraindications

Fractures close to the hip joint, which are not classified as typical medial femoral neck fractures and patients with advanced osteoarthritis of the hip who would profit from an endoprosthetic procedure.

Surgical technique

The operative procedure is shown after fracture reposition and central positioning of the guide wire as a standard course.

Postoperative Management

Early postoperative mobilization under guidance of a physiotherapist. Initially, partial weight bearing only in selected cases with severe displacement.

Results

In our patients collective the Targon® FN has been implanted in over 100 cases. Revision indications and secondary endoprosthesis were documented in only 9?% of the cases. This angular stable screw osteosynthesis system is a safe procedure to achieve patient mobility if the indications are adhered to and implantation is correctly carried out.

     

Allograft augmentation in proximal humerus fractures

Objective

Achieve stable fixation to initially start full range of motion (ROM) and to prevent secondary displacement in unstable fracture patterns and/or weak and osteoporotic bone.

Indications

(Secondarily) displaced proximal humerus fractures (PHF) with an unstable medial hinge and substantial bony deficiency, weak/osteoporotic bone, pre-existing psychiatric illnesses or patient incompliance to obey instructions.

Contraindications

Open/contaminated fractures, systemic immunodeficiency, prior graft-versus-host reaction.

Surgical technique

Deltopectoral approach. Identification of the rotator cuff. Disimpaction and reduction of the fracture, preparation of the situs. Graft preparation. Allografting. Fracture closure. Plate attachment. Definitive plate fixation. Radiological documentation. Postoperative shoulder fixation (sling).

Postoperative management

Cryotherapy, anti-inflammatory medication on demand. Shoulder sling for comfort. Full active physical therapy as tolerated without pain. Postoperative radiographs (anteroposterior, outlet, and axial [as tolerated] views) and clinical follow-up after 6 weeks and 3, 6, and 12 months.

Results

Bony union and allograft incorporation in 9 of 10 noncompliant, high-risk patients (median age 63 years) after a mean follow-up of 28.5 months. The median Constant–Murley Score was 72.0 (range 45–86). Compared to the uninjured contralateral side, flexion was impaired by 13?%, abduction by 14?%, and external rotation by 15?%. Mean correction of the initial varus displacement was 38° (51° preoperatively to 13° postoperatively).

     

Trochanteric fragility fractures

Objective

Use of standardized cement augmentation of the proximal femur nail antirotation (PFNA) for the treatment of trochanteric fragility fractures, which are associated with high morbidity and mortality, to achieve safer conditions for immediate full weight-bearing and mobilization, thus, improving preservation of function and independency of orthogeriatric patients.

Indications

Trochanteric fragility fractures (type 31-A1–3).

Contraindications

Ipsilateral arthritis of the hip, leakage of contrast agent into the hip joint, femoral neck fractures.

Surgical technique

Reduction of the fracture on a fracture table if possible, or minimally invasive open reduction of the proximal femur, i.?e., using collinear forceps if necessary. Positioning of guidewires for adjustment of the PFNA and the spiral blade, respectively. Exclusion of leakage of contrast agent and subsequent injection of TRAUMACEM? V⁺ into the femoral head–neck fragment via a trauma needle kit introduced into the spiral blade. Dynamic or static locking of the PFNA at the diaphyseal level.

Postoperative management

Immediate mobilization of the patients with full weight-bearing and secondary prevention, such as osteoporosis management is necessary to avoid further fractures in the treatment of these patients.

Results

A total of 110 patients older than 65 years underwent the procedure. Of the 72 patients available for follow-up (average age 85.3 years), all fractures healed after an average of 15.3 months. No complications related with cement augmentation were observed. Approximately 60?% of patients achieved the mobility level prior to trauma.

     

High incidence of intraoperative calcar fractures with the cementless CLS Spotorno stem

Introduction

This study reports on the incidence of intraoperative calcar fractures with the cementless Spotorno (CLS) stem, and the potential role of a learning curve and implant positioning is investigated.

Methods

After introduction of the CLS stem, 800 consecutive cementless total hip arthroplasties (THA) were analyzed. The incidence of calcar fracture in the first 400 THA was compared with the second 400 THA, in order to study a potential learning curve effect. According to the instruction for users, varus positioning of the stem was avoided and a femoral neck osteotomy was aimed relatively close to the lesser trochanter since these are assumed to be correlated with calcar fractures. Implant positioning (neck-shaft angle, femoral offset and osteotomy-lesser trochanter distance) was measured on postoperative pelvic radiographs of all THA with calcar fractures and 100 randomly selected uncomplicated control cases.

Results

Seventeen (2.1%) intraoperative calcar fractures were recorded. The incidence of calcar fracture differed between the first 400 THA (n?=?11) and the second 400 THA (n?=?6). This difference was not statistically significant (p?=?0.220); however, these numbers indicate a trend toward a learning effect. No significant difference in stem positioning nor the height of the femoral neck osteotomy was measured between THA with a calcar fracture (n?=?17) and the control cases (n?=?100).

Conclusions

We report on a high incidence of intraoperative calcar fractures with the use of a CLS stem. The risk for calcar fractures remains clinically significant even after adequate implant positioning in the hands of experienced hip surgeons. Surgeons should be aware of this implant related phenomenon and be alert on this phenomenon intraoperatively.

     

Combination of low-contact cerclage wiring and osteosynthesis in the treatment of femoral fractures

Background and purpose

Objectives were (1) to evaluate results after cerclage wiring technique for femoral primary and periprosthetic fracture (PPF); (2) to report the incidence of complications and their treatment; (3) to analyze possible prognostic factors.

Patients and methods

We analyzed 54 patients treated with different techniques associated with low-contact cerclage wires for femoral fracture. Fractures were stratified according to AO, Vancouver or Rorabeck classification. Cerclage was used as an exclusive implant in four PPFs or combined with internal devices in 50 cases. Comorbidities were assessed using Charlson Comorbidity Index. The Glasgow Outcome Scale was used to compare activities of daily living pre/postoperatively.

Results

Cerclage wires with three or four spacers were used in 22 and 32 cases, respectively. Nine patients died within 6 months. Mean follow-up of the remaining 42 patients was 10.5 months. Fracture healing was achieved in 38/42 patients (71 %), with a mean time to callus formation of 57 days and to radiographic union of 3 months (1.5–9 months). Four patients had nonunion. Survival to major complications was 92 and 70 % at 1 and 2 years, respectively, significantly better in cerclage wires with three spacers than those with four spacers (p = 0.0188). No other statistical correlations were found.

Conclusion

Cerclage wiring in difficult femoral fractures offers minimally invasive reduction and fixation technique, low cost and early holding. We reinforce the concept of “reduce with cerclage cables first, then nail” for displaced long subtrochanteric fractures and support the use of cerclage wiring for challenge PPF using low-contact wires.

Level of evidence

Therapeutic study, Level IV.

     

Rekonstruktion des medialen patellofemoralen Ligaments mit autologer Grazilissehne in patellarseitig implantatfreier Technik

Objective

Anatomic reconstruction of the medial patellofemoral ligament using autologous gracilis tendon in an implant-free technique on the patellar side to regain patellofemoral stability.

Indications

Recurrent dislocations, primary dislocation with high risk of recurrence, and dislocations with (osteo-)chondral flake fractures. As combined approach together with other procedures (trochleoplasty, tibial tubercle osteotomy). Revisions.

Contraindications

As an isolated procedure in patients with high degrees of trochlear dysplasia, chronic dislocation of the patella, and patellofemoral maltracking without instability.

Surgical technique

Harvesting of the gracilis tendon. Drilling of a V-shaped tunnel with a special aiming device in anatomic position on the medial side of the patella. Drilling of a femoral tunnel in anatomic position under fluoroscopic control. Passage of the graft, arthroscopic-guided tensioning, and femoral fixation with a biodegradable interference screw.

Postoperative management

Partial weight bearing (20 kg) for 1–2 weeks. No limitation in range of motion. No orthosis. Specific sports allowed after approximately 3 months.

Results

Perioperative complications associated specifically with the technique were observed in 1.0?% (7 of 729 cases). In a series of 72 consecutive cases from May 2010 to October 2010, the following were recorded after 4.0 ± 0.1 years: recurrent dislocations in 3.2?%, a Tegner activity score of 5.1 ± 1.8, and subjective satisfaction in 92?% (follow-up rate 87.5?%). No fracture of the patella was seen in any of our patients.

     

Incidence of and risk factors for femoral fractures in the gap between hip and knee implants

Purpose

The purpose of this study was to analyse the incidence of interprosthetic femoral fractures and describe risk factors for them.

Methods

Between 2009 and 2015, we selected patients who were carrying two implants (hip and knee) in the same femur. We collected demographic and clinical data and performed a radiological evaluation to analyse the gap between implants—the femoral canal area and total femoral area—in the axial plane. We defined interprosthetic fracture as that corresponding to a Vancouver type C fracture and types 1 and 2 according to the Su classification.

Results

We studied 68 patients who had total knee arthroplasty (TKA), and 44 patients who had total hip arthroplasty (THA); 24 patients an intramedullary nail. We found six interprosthetic fractures (8.8 %), all in patients with a non-cemented THA. There was a tendency towards statistical difference (p?=?0.08). Patients with an additional implant at the proximal femur were statistically less likely to have an interprosthetic fracture (p?=?0.04). In radiological results, we found more interprosthetic fractures in patients who had an increased femoral canal area in the axial plane just distal to the tip of the hip implant.

Conclusions

Identifying risk factors for this specific type of fracture may facilitate their prevention. Better implant stability and the presence of a gap between stems in a lower canal zone appear to hinder the occurrence of interprosthetic fractures.

     

Safety of total hip arthroplasty for femoral neck fractures using the direct anterior approach: a retrospective observational study in 86 elderly patients

Background

The femoral neck fracture is one of the most common fractures in the elderly. A variety of methods and approaches are used to treat it. Total hip arthroplasty is a preferred approach in independent, mobile, elderly patients, given its more favorable long-term outcome.Our hypothesis is that the direct anterior approach in geriatric trauma patients has a lower dislocation-rate with the advantage of early recovery due to a muscle sparing approach and therefore early possible full weight-bearing.

Methods

Patients were retrospectively sought who suffered a femoral neck fracture from 2008 to 2013. All patients were treated through a direct anterior approach and using the same brand of implants. Medical history, standardized physical exam, conventional pelvic plain and axial hip x-rays, Harris Hip Score, Merle D'Aubigné and Postel and SF-36 were assessed.

Results

Eighty-six patients were included in the study with a mean age of seventy-five years. The mortality rate was 16.7 %. Complications were encountered in nineteen patients (22.0 %) who needed operative revision and one postoperative complication (1.2 %) which could be handled conservatively. There were five intraoperative complications (5.8 %), two dislocations (2.3 %), one aseptic loosening in a non-cemented stem (1.2 %), six periprosthetic fractures in non-cemented stems (6.9 %), one displacement of a non-cemented cup (1.2 %), two early infections (2.3 %) and three hematomas (3.5 %) recorded.

Conclusions

Although the direct anterior approach is associated with a rather long learning curve we have found it to preserve the soft-tissues with no injury to abductors. It therefore shows an early advantage in elderly patients in terms of early recovery and therefore early possible full weight-bearing. Fracture treatment with dual mobility cups might lead to lower dislocation rates, but are associated with higher costs. Due to higher complication rates in non-cemented versus cemented shafts, we have changed our practice towards favoring cemented femoral stems in patients with suspected or manifest osteoporosis.

     

Surgical treatment of periprosthetic femoral fractures: a retrospective study with functional and radiological outcomes from 2010 to 2016

Background

The treatment of periprosthetic femoral fractures is a great challenge for the orthopedic surgeon and requires a knowledge of bone fracture fixation as well as skills and experience in revision surgery. The aim of this retrospective study was to evaluate the functional and radiological outcomes of periprosthetic femoral fractures surgically treated in our department from 2010 to 2016.

Materials and methods

This study involved 73 patients with a periprosthetic femoral fracture after total hip arthroplasty or hemiarthroplasty. Periprosthetic femoral fractures were classified using the Vancouver system. Functional outcomes were assessed using Harris hip score, Palmer Parker score, SF-36 score and ambulatory status. Radiological findings were classified using Beals and Tower’s criteria.

Results

The mean age of patients was 79.6 years old. Local risks factors were identified in 67% of the patients, principally osteoporosis (63.0%), followed by osteolysis (26.0%) and loosening of the stem (8.2%). According to the Vancouver classification, there were 10 type A, 49 type B and 14 type C fractures. Of the type B fractures, 26 were B1, 17 were B2 and 6 were B3. Applying Beals and Tower’s criteria, radiological results were excellent in 24 patients (32.9%), good in 35 (47.9%) and poor in 14 (19.2%). The mean Harris hip score post-operatively was 72.5.

Conclusions

These kinds of fractures should be assessed individually and the optimal treatment plan should be made in accordance with the bone stock quality, stem stability, location of the fracture and patient expectations.

     

A comparative study of using non-hip bone density inputs with FRAX®

Summary

Use of lumbar spine T-score or minimum T-score as a bone mineral density (BMD) input to the FRAX® algorithm led to miscalibration compared with the recommended femoral neck input. Use of a weighted mean between the lumbar spine and femoral neck T-scores was found to provide an arithmetically equivalent result to a previously described offset adjustment.

Introduction

FRAX assumes that the BMD input, when used in the calculation, is from the femoral neck. Use of other BMD inputs is not recommended, but there are no studies describing how this affects the performance of FRAX.

Methods

Ten-year probabilities of a major osteoporotic fracture were calculated with different BMD inputs for 20,477 women and men aged 50 years and older from Manitoba, Canada. FRAX probability calculated with femoral neck BMD was designated the reference method. We also derived FRAX probabilities where the BMD input was based upon the lumbar spine T-score, minimum T-score (lumbar spine or femoral neck), weighted mean T-score (lumbar spine or femoral neck), or used an adjustment for the spine–hip T-score difference (offset). Fracture outcomes were assessed using a population-based administrative data repository.

Results

All FRAX models showed good risk stratification with minimal differences. There was no consistent improvement in FRAX performance when lumbar spine or minimum T-score were used as inputs, but calibration was adversely affected due to higher mean fracture probabilities compared with the femoral neck. The weighted mean T-score was found to be equivalent to the spine–hip T-score offset adjustment, and both slightly improved risk classification without a change in calibration.

Conclusions

The choice of BMD input to the FRAX model has a large effect on performance. The lumbar spine T-score or minimum T-score should not be used as inputs to the FRAX algorithm. Use of a weighted mean between the lumbar spine and femoral neck T-scores slightly improves risk classification.

     

Cementless modular neck stems: are they a safe option in primary total hip arthroplasty?

Purpose

The objective was to assess aseptic complications and functional outcome using a primary total hip arthroplasty with modular neck.

Methods

Prospective cohort of 317 consecutive patients. The mean age was 61.1 (range, 41–84) years. The H-Max-M model (Lima, Italy) system was used in all patients. The functional assessment was made by the Harris Hip Score, Short Form-36 (SF-36), Western Ontario and McMaster Universities Osteoarthritis Index and visual analogue scale for pain. Radiological outcomes were also assessed, and adverse events and complications were noted.

Results

The mean follow-up was 6.1 (range, 2–8) years. Functional outcome significantly improved in most patients. There were 3 deep infections (0.9%) and 17 aseptic complications (5.3%) including 1 intraoperative acetabular fracture, 3 later periprosthetic femoral fractures, 1 broken ceramic insert, 1 acetabular loosening, 3 femoral loosening and 1 broken titanium modular neck in a obese patient. No pseudotumors or elevated serum levels of metal ions were found among the patients with radiolucent lines or aseptic loosening.

Conclusions

The findings in the present study showed that the H-MAX-M stem provided satisfactory functional outcome in most patients with a low rate of complications attributable to the modular neck design. We consider that using this novel modular neck-stem coupling design can be an alternative to the conventional monoblock stems in patients without overweight.