Loosely Implanted Cementless Stems May Become Rotationally Stable After Loading

Background

Experimental studies have suggested that initial micromotion of cementless components may lead to failure of osteointegration. Roentgen stereophotogrammetric analyses have shown durable implant fixation can be achieved long-term even when initial instability exists, as evidenced by subsidence. However improved implant stability as a result of subsidence, before osteointegration, has not been shown biomechanically.

Questions/purposes

We asked whether insertionally loose cementless tapered femoral stems show (1) less rotational stability (more toggle); (2) more subsidence; and (3) reduced ability to resist torsion (lower initial construct stiffness), lower torque at failure, and greater rotation to failure in comparison to well-fixed cementless tapered femoral stems.

Methods

Ten matched pairs of cadaveric femurs were implanted with well-fixed and loose cementless tapered stems. The loose stem construct was obtained by appropriately broaching the femur but afterwards inserting a stem one size smaller than that broached. Femoral stem rotational stability of implanted femurs was tested by measuring the angular rotation (ie, toggle) required to produce a torque of 2 N-m at 0 N, 250 N, and 500 N vertical load in 25° adduction simulating single-legged stance. Subsidence was measured as vertical movement during the toggle tests. Then at 500 N initial vertical load, femoral stems were externally rotated to failure. The construct stiffness between 5 and 40 N-m was determined to assess ability to resist torsion. The torque and rotation to failure were recorded to compare failure characteristics. Groups were compared using mixed model ANOVA followed by Tukey–Kramer post hoc pairwise comparison for toggle and subsidence tests and by Student’s paired t-tests for stiffness, torque at failure, and rotation to failure tests.

Results

Loose tapered cementless stems were less stable (ie, more toggle) than well-fixed at 0 N of load (p < 0.0001), but no difference was detectable in toggle between loose and well-fixed stems at 250 N (p = 0.7019) and 500 N (p = 0.9970). Loose tapered cementless stems showed significant subsidence at 250 N (p < 0.0001) and 500 N (p < 0.0001), which was not found in the well-fixed stems at 250 N (p = 0.8813) and 500 N (p = 0.1621). Torsional stiffness was lower for loose stems as compared with well-fixed stems (p = 0.0033). No difference in torque at failure (p = 0.7568) or rotation to failure (p = 0.2629) was detected between loose and well-fixed stems.

Conclusions

In this study, we observed that insertionally loose cementless stems have the ability to subside and become rotationally stable with loading. They did not exhibit a lower torque or rotation to failure in comparison to well-fixed stems when under simulated single-legged stance.

Clinical Relevance

Secondary rotational stabilization may prevent insertionally loose tapered stems from producing a stress pattern that predisposes to early postoperative periprosthetic fracture around loose cemented stems.     

High union rates of locking compression plating with cortical strut allograft for type B1 periprosthetic femoral fractures

Purpose

Unified classification system (UCS) type B1 periprosthetic femoral fractures are associated with many complications, and management decisions continue to be controversial. The purpose of this study was to evaluate outcomes of UCS type B1 periprosthetic femoral fractures treated by locking compression plating with strut allograft augmentation.

Materials and methods

We retrospectively reviewed 17 consecutive UCS type B1 periprosthetic femoral fractures treated by open reduction and internal fixation using a lateral locking compression plate supplemented with an anterior cortical strut allograft. There was one man and 16 women with an average age of 74 years (range, 57–92 years). All had a cementless hip arthroplasty, and eight of the arthroplasties were revisions.

Results

The mean duration of follow-up was 28 months (range, 12–74 months). All 17 fractures healed successfully at a mean of 20 weeks (range, 12–30 weeks). The mean post-operative Harris hip score was 86 points (range, 77–95 points). No mechanical complications such as failure of plate or screws and malalignment were noted. According to the graft-remodeling classification of Emerson et al., a partial bridging was observed in nine and a complete bridging in eight. Two patients required a removal of the plate due to irritation of the iliotibial band. No femoral stem loosening or deep infection was observed.

Conclusion

Our findings indicate that open reduction and internal fixation of UCS type B1 periprosthetic femoral fractures using a lateral locking compression plate supplemented with anterior cortical strut allograft provides adequate mechanical stability of fracture fixation and enhances the fracture healing.

     

Hemiarthroplasty for Displaced Femoral Neck Fractures in the Elderly Has a Low Conversion Rate

Background

Hemiarthroplasty (HA) has been a mainstay treatment for displaced femoral neck fractures for many years. The purpose of this study was to report the conversion rate of HA to total hip arthroplasty (THA) for displaced femoral neck fractures and compare outcomes between implant constructs (bipolar vs unipolar), fixation options (cemented vs cementless stems), and age groups (<75 years vs ≥75 years).

The Effect of Prophylactic Cerclage Wires in Primary Total Hip Arthroplasty: A Biomechanical Study

Background

Despite literature to support the use of various cerclage techniques to address intraoperative femoral fractures in total hip arthroplasty, there are limited data to support prophylactic cerclage wiring of the femur during cementless implant placement. This study aims to evaluate the effect of prophylactic calcar cerclage wires on the biomechanical parameters required to produce periprosthetic femoral fractures and on the morphology of these fracture patterns in stable cementless femoral implants.

Reduced Incidence of Intraoperative Femur Fracture With a Second-Generation Tapered Wedge Stem

Background

Intraoperative fractures during total hip arthroplasty (THA) are more common when using cementless stems. The purpose of this study was to investigate the impact of a new shorter second-generation cementless, tapered wedge stem with improved proximal femoral fit in reducing the incidence of intraoperative fracture.

Management of Vancouver type B2 and B3 femoral periprosthetic fractures using an uncemented extensively porous-coated long femoral stem prosthesis

Objective

The purpose of this study was to evaluate the clinical results of femoral revision using an uncemented extensively porous-coated long femoral stems with or without onlay strut allografts in the treatment of Vancouver type B2 and B3 periprosthetic femoral fractures.

Materials and methods

We retrospectively reviewed 17 cases of periprosthetic femoral fracture (eight B2 and nine B3) treated with the uncemented extensively porous-coated long femoral stem. Clinical outcomes were assessed with Harris Hip Score and Barthel ADL index. Radiological evaluations were conducted using Beals and Towers’ criteria. Any complication during the follow-up period was recorded.

Results

The average follow-up period was 41.7 ± 31.08 (range, 15–132) months. The average Harris Hip Score was 68.2 ± 18.4 (range, 32–100), and the average Barthel ADL index was 80.1 ± 19.75 (range, 30–100) points at the final follow-up. All fractures were united, and a good graft consolidation was achieved in 5 of 9 cases. There was femoral stem subsidence in 4 cases less than 10 mm without an evidence of loosening both radiologically and clinically. The radiological results using Beals and Towers’ criteria were excellent in eight hips, good in five and poor in four.

Conclusions

An uncemented extensively porous-coated long femoral stem together with or without onlay strut allografts provides a good fracture stability that promotes fracture healing and offers a successful solution for the management of Vancouver type B2 and B3 femoral periprosthetic fractures.     

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.

     

Cortical Strut Allograft Support of Modular Femoral Junctions During Revision Total Hip Arthroplasty

Background

There is risk of junction failure when using modular femoral stems for revision total hip arthroplasty (THA), especially with loss of bone stock in the proximal femur. Using a cortical strut allograft may provide additional support of a modular femoral construct in revision THA.

Cemented versus uncemented hemiarthroplasty of the hip in patients with a femoral neck fracture: a comparison of two modern stem design implants

Purpose

We wished to compare the outcome of two types of cemented and uncemented modern stem design implants after hemiarthroplasty, with both an Orthopaedic Data Evaluation Panel rating of 10A.

Methods

This retrospective study compares data obtained from two centres, with a total study population of 655 (n?=?393 cemented, n?=?262 uncemented). Patients were matched at baseline for gender, age, surgery side, American Society of Anesthesiologists score, body mass index and pre-operative haemoglobin level. Outcome measurements were prosthesis-related complications, pre- and post-operative, with reoperation rate and mortality and other complications after 1 year, surgery time, blood loss and immobility at discharge.

Results

There were no significant differences in mortality after 1 year, total other complications, immobility at the time of discharge and total prosthesis-related complications between both groups. Significantly more periprosthetic fractures and post-operative infections were seen in the uncemented group with significantly more reoperations compared to the cemented group. Significant differences were seen in cardiovascular complications, blood loss and surgery time in favour of the uncemented group.

Conclusions

In consequence of the significant higher prosthesis-related complications (e.g. infections, periprosthetic fractures and reoperations) in the uncemented group in this study, we recommend cemented hemiarthroplasty in patients with a femoral neck fracture.

Level of evidence

Level III, Case Controlled Study.

     

The benefit of the systematic revision of the acetabular implant in favor of a dual mobility articulation during the treatment of periprosthetic fractures of the femur: a 49 cases prospective comparative study

Introduction

The SOFCOT symposium (2005) on periprosthetic fractures of the femur (PFFs) highlighted a high rate of dislocation (15.6% at 6 months) after change of prosthesis. So far, no study has ever proved the benefit of dual-mobility articulation during PFFs revisions. We conducted a comparative study on two prospective cohorts in order to (1) assess the influence of systematic acetabular revision in favor of a double mobility on dislocation rate (2) and in order to evaluate the rate of morbidity associated with this extra surgical procedure.

Hypothesis

A systematic replacement of the cup in favor of a dual-mobility articulation enables to reduce the dislocation rate in PFFs revisions without increasing morbidity.

Methodology

We compared two prospective multicenter cohorts over a year (2005 and 2015) using the same methodology. Any fracture around hip prosthesis which occurred 3 months at least after surgery was included. Data collection was clinical and radiological on preoperative, intraoperative and 6 months after surgery. The 2015 “bipolar” group (n = 24) included patients who had a bipolar revision (both femoral and dual-mobility articulation). The 2005 “unipolar” group (n = 25) included patients who had only a femoral implant revision. Patients were comparable by age (p = 0.36), sex (p = 0.91), ASA score (p = 0.36), history of prosthetic revision (p = 1.00), Katz score (p = 0.50) and the type of fracture according to the Vancouver classification (p = 0.55).

Results

There was a 4% rate of dislocation in the “bipolar group” while there was 21% rate of dislocation in the “unipolar group” (8% of recurrent dislocation) (p = 0.19). The rate of all-cause complications 6 months after surgery was not significantly different (p = 0.07): 12.5% in the 2015 “bipolar” cohort (one dislocation, one non-symptomatic cup migration and one pseudarthrosis of the major trochanter) versus 35% in the “unipolar” cohort (5 dislocations, 1 major trochanter fracture and 1 femur pseudarthrosis, 1 secondary displacement associated with a superficial infection). The surgical revision after 6 months was not significantly different (1/23 or 4% vs. 4/25 or 16%, p = 0.35).

Conclusion

We confirm the low rate of dislocations after fitting a dual-mobility cup in case of revision of the femoral side in case of periprosthetic femoral fracture, as well as the need for additional cases to be carried out upon further studies to significantly confirm the interest of preventing instability after femoral revision.

     

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.

     

Three to seven year follow-up of a tapered modular femoral prosthesis in revision total hip arthroplasty

Purpose

Modular femoral prostheses can provide independent distal fixation and intraoperative flexibility and are being used increasingly, especially in patients with proximal femoral bone defects. This retrospective clinical study evaluated whether modular prostheses were effective and reliable implants for femoral revision.

Method

This case series consisted of 58 patients who underwent hip revision with a tapered modular femoral prosthesis at our institution between 2004 and 2008. Mean patient age at surgery was 64 years (range 18–86 years). Femoral bone defects before revision surgery were evaluated using the Paprosky classification. All patients were followed for a minimum of 3 years (mean 4.3 years, range 3–7 years) with clinical and radiographic evaluation. Re-revisions and complications were also recorded.

Results

Two stems required re-revision, one each for recurrent deep infection and periprosthetic fracture. At last follow-up, the Harris Hip Score and Visual Analog Pain Scores had improved significantly, the median radiographic stem migration was 1.6 mm, leg length discrepancy was corrected in 64 % of the patients and osseointegration occurred in 90 %. Complications included intraoperative fracture in 10 (17 %) patients and hip dislocation in 2 (3 %).

Conclusion

Modular femoral components can improve hip function, provide distal fixation, equalize leg length, and result in fewer complications when used to revise failed femoral components.     

Periprosthetic bone mineral density after total hip arthroplasty with an AMIStem or Quadra femoral component performed by a minimally invasive anterior approach (AMIS): a prospective randomized clinical dual-energy X-ray absorptiometry study

Introduction

This prospective 12 months of dual-energy X-ray absorptiometry (DEXA) study evaluated differences in periprosthetic bone mineral density in 40 patients undergoing cementless total hip arthroplasty (THA) by a minimally invasive anterior approach (AMIS), using Medacta AMIStem or Quadra stems. Both stems are straight rectangular. AMIStem shows reduced lateral flare and length in comparison to Quadra.

Objectives

The main goal of the study is to verify if bone mineral density is equivalent following THA with the AMIStem and Quadra femoral components.

Methods

Forty patients were randomly allocated to the Quadra and AMIStem groups. Three patients were lost to follow-up because they moved to another town, and revision surgery was performed on one patient due to periprosthetic fracture after a car accident. Patients were examined clinically and underwent DEXA preoperatively and at 1 week, 6 weeks, 6 months, and 1 year after THA. Patients enrolled had no preexisting lower limb arthroplasty and no osteoporosis.

Results

Harris hip score increased significantly for Quadra stem 5.3?±?14.1 and AMIStem 41.0?±?13.4. The high-activity hip score increased significantly for Quadra stem 3.8 ±2.2 and AMIStem 4.1?±?2.4. Considering 0.15 mg/cm² as an acceptable difference, bone mineral density for AMIStem and Quadra groups was statistically equivalent. A limited remodeling process with slight bone loss in the proximal calcar region R7, as expected after implantation of uncemented components, was observed for both stems.

Conclusions

The study demonstrates that the two stems are statistically equivalent in all zones at all time points investigated.     

No Difference in Periprosthetic Bone Loss and Fixation Between a Standard-Length Stem and a Shorter Version in Cementless Total Hip Arthroplasty. A Randomized Controlled Trial

Background

Cementless femoral stems in total hip arthroplasty provide dependable clinical and radiographic results in the treatment of osteoarthritis. Stem length might affect the preservation of proximal bone stock and stability. We hypothesized that a shorter stem decreases proximal bone loss without affecting implant stability.

Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems

Background

Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs.

Anatomic stem design reduces risk of thin cement mantles in primary hip replacement

Purpose

To analyse the influence of femoral stem design in the lateral plane (anatomic vs. straight) on the cement mantle quality.

Method

In this consecutive multi-surgeon radiographic study we determined, Dorr grading, cement mantle quality (Barrack) and mantle thickness using Gruen zones 1–14 in 280 primary cemented total hip replacements, divided into two groups (140 anatomic Biomet Olympia, 140 straight Exeter Universal Series).

Results

Twenty-three per cent of the straight Exeter Universal stems had a cement mantle of <2 mm thickness in Gruen zone 8 and 25% in Gruen zone 9, compared to 0.7% of the anatomical Olympia stems in Gruen zone 8 and 1.4% in Gruen zone 9. The difference between the two groups was statistically significant (P < 0.001). In all other zones no significant differences were found.

Conclusion

This radiological study confirms that femoral stems with an anatomical curve in the lateral plane carry a lower risk of thin cement mantles (especially in Gruen zones 8 and 9) than straight stems. Cement mantle analysis in one radiographic plane only is insufficient.     

Which AO/OTA 31-A2 pertrochanteric fractures can be treated with a dynamic hip screw without developing a lateral wall fracture? A CT-based study

Purpose

To determine whether radiographic measurements derived from standard computed tomography (CT) evaluation can be used to predict likelihood of a peri-operative lateral femoral wall fracture in AO/OTA 31-A2 pertrochanteric fractures treated with a dynamic hip screw (DHS).

Methods

Fifty-one patients with AO/OTA 31-A2 classified pertrochanteric fractures were evaluated using a pre-operative CT scan of the pelvis with both hips. Dimensions of the lateral wall were calculated for each patient using four parameters: (1) height of the lateral wall above the vastus ridge; (2) circumference of the lateral wall 2 cm below the vastus ridge at an angle of 135°; this circumference was further divided into an anterior, lateral and posterior component; (3) cortical thickness at the centre of the lateral component of the lateral wall; and (4) cortical index. All patients were treated with a 135° DHS. Postoperative radiographs were assessed for lateral femoral wall fracture.

Results

Patients with a lateral wall fracture (17/51) had a smaller circumference (4.47 cm vs 5.44 cm p value?<0.001) as well as a lower height of the lateral femoral wall (1.37 cm vs 2.21 p value?<?0.001). Analysis of the three components of the circumference revealed a significant difference for the anterior component only and not for the lateral and posterior components. There was no statistical difference in the cortical thickness or cortical index in the two groups. The cutoff values for height of the lateral wall and anterior component were calculated using ROC curves and found to be 1.68 cm (AUC 0.918) and 2.10 cm (AUC 0.851) respectively.

Conclusion

AO/OTA 31-A2 pertrochanteric fractures with a lateral wall height of > 1.68 cm and an anterior component of > 2.10 cm in circumference are not likely to sustain a lateral wall fracture when treated with a DHS.

     

Revision Hip Arthroplasty Using a Modular,Cementless Femoral Stem: Intermediate-Term Follow-Up

Background

Modular femoral stem provides flexibility in femoral reconstruction, ensuring improved “fit and fill”. However, there are risks of junction failure and corrosion, as well as cost concerns in the use of modular femoral stems.