Fracture of fully coated echelon femoral stems in revision total hip arthroplasty

Fracture of Contemporary Femoral Stems: Common Trends in This Rare Occurrence

BACKGROUND

Fracture of contemporary femoral stems is a rare occurrence in total hip arthroplasty (THA). A knowledge gap remains regarding manufacturing, patient, and surgeon factors that may contribute to the increased risk of this complication.

METHODS

We analyzed 13 contemporary fractured porous coated femoral stems of various designs to determine cause and contributing factors of mechanical failure. Cases included 12 men and one woman who had an average age at index surgery of 53 years (range, 34 to 76). There were ten of 13 patients who had a body mass index (BMI) greater than 30 (obese); 3 of the 10 had a BMI greater than 40. The mean time to fracture was 7.6 years (range, 7 months to 12 years).

RESULTS

There were four titanium alloy stems that fractured an average of 3.6 years post-revision surgery for head/cup exchange, and had associated iatrogenic mechanical and electrocautery damage to the femoral neck at fracture initiation sites. There were six modular stems that failed at the stem-sleeve or stem-neck interfaces with evidence of fretting corrosion. For two stem-neck fractures, mis-matched head/stem combinations from different manufacturers resulted in untested mechanical offsets and loading. There were two proximal neck fractures and one mid-shaft fracture of coated cobalt-chromium alloy stems that occurred in three obese men. The neck fractures (10 to 12 years) were well-fixed stems. Lack of proximal fixation contributed to the mid-shaft fracture (7 months).

CONCLUSION

While rare, femoral stem fractures pose catastrophic outcomes in primary and revision THA. Manufacturing, patient, and surgical factors contributing to stem failures were identified, including patient obesity, heat-treatment reduction of mechanical properties, iatrogenic implant damage, and mixing of different vendor stems and heads.

Proximal femoral replacement for non-neoplastic conditions: a systematic review on current outcomes

Proximal femoral replacement (PFR) is a well-established treatment for neoplasia of the proximal femur. The use of this surgical technique for non-neoplastic conditions has increased over the years. We carried out a systematic review of the literature to study the indications, complications, and functional results when PFR is used for non-neoplastic conditions. Twenty-seven studies were included in the review with a total of 828 PFRs with a mean follow-up of 50 months (range 1-225 months). The main indications were infection (28%), periprosthetic fracture (27%), aseptic loosening (22%), and fracture (16%). The rate of reoperation was 20.3% overall. The overall revision rate was 15.4%. The main complications were dislocation (10.2%) and infection (7.3%). After 2010, the rates of reoperation (25.5% versus 18.2%), loosening (9.4% versus 3.2%), and dislocation (15.7% versus 7.9%) were lower than before 2010. The 30-day mortality ranged from 0% to 9%. The hip function scores improved post-surgery. In conclusion, the use of PFR in non-neoplastic conditions remains a marginal tool, associated with low direct mortality and high complication rates, but we expect its use to increase in the near future.

Nonoperative Treatment of a Fractured Uncemented Extensively Coated Femoral Stem: A Case Report with 2-Year Follow-up

CASE

A 62-year-old man who underwent total hip arthroplasty (THA) 17 years earlier presented with a fractured uncemented extensively coated diaphyseal engaging femoral stem. Treatment options, including revision surgery, were discussed, and the patient elected for nonoperative treatment. At 2 years of follow-up, the patient is asymptomatic, radiographs are stable, and he lives an active lifestyle without restrictions.

CONCLUSION

Fractures of well-fixed femoral prostheses are rare complications of THA and almost universally require revision surgery. Nonoperative treatment without activity restrictions may be a viable treatment option in select patients to preserve function and maintain quality of life.

Minimum ten-year results in revision total hip arthroplasty using titanium fully porous long stem

PURPOSE

The fully porous long stem could be used for diaphyseal locking and achieve bypass fixation in revision total hip arthroplasty (THA). This study evaluated long-term results for fully porous long stems made of titanium alloy in revision THA.

METHODS

Between 2003 and 2010, 45 consecutive femoral revisions were performed using fully porous long stems. Thirty-eight hips had complete clinical and radiographic data for a mean of 13.8 years (range, 10-16.7 years). Femoral bone loss was Paprosky type II in 14 hips, type IIIA in 18 hips, and type IIIB in six hips. Clinical results were analyzed using the Merle d'Aubigné and Postel scoring system. Femoral stress shielding was graded. Radiological loosening of the femoral component was evaluated. Kaplan-Meier survival analysis was performed with revision for any reason as the end-point.

RESULTS

Mean Merle d'Aubigné and Postel score improved significantly from 10.7 before revision to 14.5 at latest follow-up (p < 0.001). Third-degree stress shielding was found in seven hips, and fourth degree in 11 hips. Radiological femoral loosening occurred in one hip, which was revised. Another hip was revised for stem fracture. Kaplan-Meier cumulative survival rate was 94.7% at both ten and 15 years.

CONCLUSION

Although stress shielding is a concern with fully porous stems, this stem was useful in revision THA and provided satisfactory long-term results in hips with Paprosky types II, IIIA, and IIIB.

Bilateral Fractures of Anatomic Medullary Locking Hip Arthroplasty Stems in a Single Patient: A Case Report

Introduction:

Stem fracture is a rare complication of total hip arthroplasty (THA) using fully porous-coated femoral stems. Bilateral fractures in a single patient have not been previously reported.

Case Report:

A 48-year-old female underwent bilateral staged primary THA with fully porous-coated anatomic medullary locking femoral prostheses. She subsequently sustained stem fractures of her right and left prostheses in the 13thand 14thyears after their implantation, respectively.

Conclusion:

The bilateral nature of this rare complication in a single patient supports the notion that stem fracture results from a mismatch between the mechanical stresses encountered in vivo and the structural properties of small-diameter stems. Surgeons should be cognizant of this potential complication when evaluating patients at long-term follow-up with new-onset pain.

Non-contemporaneous bilateral stem fractures occurring after staged bilateral hip revision using extensively porous-coated cylindrical femoral stems: a case report

Background

Distally fixed cylindrical femoral stems extensively coated with porous materials are widely used in revision and total hip arthroplasty surgeries. Stem fracture is an uncommon complication; few case reports have been published.

Case presentation

We report the case of a 51-year-old male exhibiting extensively porous-coated cylindrical femoral stems fracture after staged bilateral hip revision. His body mass index was 24.22 kg/m². The major risk factor was poor proximal bony support; and femoral stems with smaller diameter.

Conclusions

Certain patients are at high risk of non-contemporaneous, bilateral femoral stem fractures. It remains unclear whether fracture of the contralateral femoral stem is an inevitable fatigue fracture or reflects the increased weight imposed on the contralateral hip after the first revision. We recommend that a strut bone graft be placed to support the proximal bone, and that non-modular tapered femoral stems be employed in such patients.

Case Report and Literature Review of Periprosthetic Atypical Femoral Fractures After Total Hip Arthroplasty

We describe a case of periprosthetic femoral fracture with 5 major features of an atypical femoral fracture (AFF) and localized cortical thickening at the fracture site, which is characteristic of an AFF. An 81-year-old female patient had undergone cementless total hip arthroplasty for a right femoral neck fracture at the age of 66, and had been taking oral alendronate since then. At the age of 79, she developed spontaneous right thigh pain. Radiographs showed lateral cortical thickening and pedestal formation around the end of the femoral component. She was advised to discontinue oral alendronate and change to eldecalcitol. At the age of 81, she developed sudden severe pain when standing up from a seated position and was not able to walk. Radiographs showed a periprosthetic femoral fracture with 5 major features of AFF at the site of localized cortical thickening. We diagnosed a Vancouver type B1 periprosthetic femoral fracture. She underwent open reduction and internal fixation (ORIF) with an NCB^® Periprosthetic Femur Plate System with cable grips. Daily subcutaneous injection of teriparatide and low intensity pulsed ultrasound therapy were performed to stimulate bone healing. She was able to walk without assistance at 4 months after ORIF. Radiographs showed adequate bridging callus and a disappearing fracture line. This case was diagnosed as a periprosthetic atypical femoral fracture (PAFF), because a periprosthetic fracture is excluded from the definition of AFF. Similar to AFF, PAFF exhibits poor clinical outcomes. The approach to treating PAFF should be decided after considering the pathogenesis.

Fracture of an S-ROM stem at the sleeve-stem junction

Fracture of a well-ingrown femoral component is a rare and often challenging complication. Modular junctions and sleeve interfaces have been identified as one potential point of weakness with corrosion and fretting being contributing factors to ultimate femoral component fracture. Stem fractures at the sleeve interface were reported occasionally for the proximal ingrowth modular Emperion System (Smith and Nephew, Memphis, TN). However, this failure mechanism has been reported infrequently, often associated with corrosion at the modular junction, for the similarly designed S-ROM system (DePuy Orthopedics Inc., Warsaw, IN). We present the case of a 52-year-old patient, with a body weight of 84 kg (185 lbs) and a body mass index of 30.6 kg/m², who suffered a fatigue fracture of a 14 × 09 × 130 mm S-ROM stem 42 months after implantation. The present study presents the results of the surface analysis, discusses possible failure mechanisms, provides treatment guidelines, and a review of the literature revealing 15 cases of failure at the level of the stem-sleeve junction. In particular, modifiable risk factors for potential stem failure, including stem diameter, stem offset, and the resulting cantilever bending forces on the proximal sleeve-stem junction, are discussed in detail.

Fracture of cobalt chrome, fully-coat beaded femoral revision long stem, a clinical outcomes study

Background

Femoral bone loss during revision total hip arthroplasty poses a challenging problem. Bypass fixation over the diaphysis has achieved clinical success in cases of proximal femoral bone loss. Fracture of cementless, fully bead-coated femoral stem is an uncommon complication. The purpose of this study is to analyze the patients with and without fracture stem and find out the possible risk factors.

Methods

From 2006 to 2012, a total of 251 revision long stems (Zimmer, Warsaw, IN) were implanted. In the same period, 17 broken stems that underwent treatment were included for analysis. Patients' demographic data, pattern of femoral bone loss, stem size, medial calcar support in the proximal region of the stem, and the timing of stem breakage were collected and analyzed.

Results

The stem size in patients with a broken stem was smaller (p < 0.001), and medial calcar defect was 12.4% and 100% (p < 0.001), respectively. The bone defect was greater in broken group (p = 0.024). The mean duration between revision surgery and stem breakage was 58.07 ± 36.98 months. Smaller stem size, greater bone defect, and inadequate medial calcar bone support were major risk factors for stem breakage.

Conclusions

Bypass fixation in the distal diaphysis with a long stem prosthesis without adequate bone support over medial calcar area may cause stress concentration in the long stem and a fatigue fracture. Use of a smaller prosthesis is the major risk of stem broken. It is essential to repair the proximal femoral bone deficiency and implant selection for better metaphyseal engagement to prevent further stem complications.

Level of evidence

Level III, case control study.

Fracture risk of tapered modular revision stems: a failure analysis

Fractures of well-ingrown femoral components are a rare and often challenging complication after revision total hip arthroplasty. Prior series have documented catastrophic failure at the modular junction of revision femoral components. However, to the authors' knowledge, there has been only 1 report of a mid-stem fracture of a modular tapered revision stem. The present article reports 2 cases of fatigue fractures (14 months and 10 years after implantation) of a tapered modular revision stem. It presents the results of the fracture surface analysis, discusses the etiology of failure, and presents the authors' recommendations on how to best avoid this complication.

Fracture of a spline of the femoral stem in an ingrown modular hip implant

INTRODUCTION

Physiologic strain patterns of the femur are altered by the bending stiffness of the implant as well as the loading pattern of the implant itself. The Savish Range of Motion (S-ROM) femoral stem has been designed with flutes (to decrease distal material) and with a coronal slot (to decrease stiffness).

MATERIALS

The purpose of this case report is to briefly discuss design characteristics of femoral stems and their relationship to thigh pain as well as to describe the only report in the literature of a fracture of the anterior spline of a S-ROM prosthesis at the coronal slot.

RESULTS

The femoral stem fractured at the coronal slot due to multiple bending moments in a small diameter stem.

CONCLUSIONS

The proximal metaphyseal sleeve remains well fixed and the patient is functioning well without pain nearly a year after the identification of the fracture on routine follow-up.

Cementless Corail™ femoral stems with laser neck etching: Long-term survival, rupture rate and risk factors in 295 stems

INTRODUCTION

Implant neck fracture involving a non-modular femoral stem is rare in primary total hip arthroplasty (THA). Occasional cases have been reported following laser etching of the Corail(tm) stem, but risk factors have not been precisely determined. We therefore performed a retrospective study on a series of Corail(tm) stems with laser neck etching, in order to: (1) determine the exact implant neck fracture rate at 10 years, and (2) identify associated risk factors.

HYPOTHESIS

Laser etching increases the rate of implant neck fracture.

MATERIALS AND METHODS

Between October 2002 and December 2003, 295 THAs were consecutively performed using the Corail(tm) stem with laser neck etching, in 286 patients: 151 male (53%), 135 female (47%); mean age, 63 years (range, 18-89 years); mean weight, 73kg (range, 45-120kg). Stems were standard in 240 cases (81%) and lateralized in 55 (19%). The main assessment criterion was stem replacement for implant neck fracture.

RESULTS

At a mean 10 years' follow-up (range, 1-11 years), 11 patients were lost to follow-up (4%) and 35 had died (12%) (with stem in situ). Overall 10-year stem survival was 91% (95% CI: [87-94%]). Sixteen patients (5.4%) underwent revision surgery for implant neck fracture, 6 (2%) bone and joint infection and in 4 cases (1.3%) the stem was replaced preventively for fracture risk suspected during a revision procedure on the cup. All fractures were of the fatigue type, implicating implant neck laser etching. Mean time to fracture was 4.5 years (range, 1.4-9.8 years). Risk factors comprised: weight>80kg (P=0.002) (OR=5.7; 95% CI: 1.9-17), age<60 years (P=0.02) (OR=3.4; 95% CI: 1.2-9.6), male gender (P=0.01) (OR=14.8; 95% CI: 1.9-113) and lateralized stem (P<0.001) (OR=6.5, 95% CI: 2.3-18).

CONCLUSION

The present 5.4% fracture rate was higher than in registry data (<1%). Fracture mechanisms involved excessive stress in an area under tension, leading to fatigue fracture. Male gender, high weight and young age were risk factors, as in the literature for fatigue fracture. Location and depth of laser etching induced fatigue fracture. The study demonstrated that laser etching creates an area of weakness in the implant neck and should therefore be eschewed in this part of the femoral stem.

LEVEL OF EVIDENCE

IV, retrospective study.

Revision total hip arthroplasty after removal of a fractured well-fixed extensively porous-coated femoral component using a trephine

When fracture of an extensively porous-coated femoral component occurs, its removal at revision total hip arthroplasty (THA) may require a femoral osteotomy and the use of a trephine. The remaining cortical bone after using the trephine may develop thermally induced necrosis. A retrospective review identified 11 fractured, well-fixed, uncemented, extensively porous-coated femoral components requiring removal using a trephine with a minimum of two years of follow-up. The mean time to failure was 4.6 years (1.7 to 9.1, standard deviation (sd) 2.3). These were revised using a larger extensively porous coated component, fluted tapered modular component, a proximally coated modular component, or a proximal femoral replacement. The mean clinical follow-up after revision THA was 4.9 years (2 to 22, sd 3.1). The mean diameter of the femoral component increased from 12.7 mm (sd 1.9) to 16.2 mm (sd 3.4; p > 0.001). Two revision components had radiographic evidence of subsidence that remained radiographically stable at final follow-up. The most common post-operative complication was instability affecting six patients (54.5%) on at least one occasion. A total of four patients (36.4%) required further revision: three for instability and one for fracture of the revision component. There was no statistically significant difference in the mean Harris hip score before implant fracture (82.4; sd 18.3) and after trephine removal and revision THA (81.2; sd 14.8, p = 0.918). These findings suggest that removal of a fractured, well-fixed, uncemented, extensively porous-coated femoral component using a trephine does not compromise subsequent fixation at revision THA and the patient's pre-operative level of function can be restored. However, the loss of proximal bone stock before revision may be associated with a high rate of dislocation post-operatively.

Fracture of Fully-coated Femoral Stem after Primary Total Hip Arthroplasty for Nonunion of Intertrochanteric Fracture: A Case Report

Femoral stem fracture is an uncommon reason for the failure of total hip arthroplasty, with only 16 cases of fully coated stem fractures reported to date. Here we report a case in which a fully coated primary femoral stem fracture occurred after conversion to total hip arthroplasty for the non-union of an intertrochanteric fracture of the femur. Metallurgic evaluation of the etiology and mechanism revealed that the fracture was initiated by fatigue-related failure and completed by ductile failure on the posterior side of the fracture. Considering the recent trend of treating an intertrochanteric fracture with hip arthroplasty, possible stem failure should be considered, since most patients will have at least one of the known risk factors for stem fracture.

Fracture of Uncemented Revision Femoral Stems in three Arthroplasty Patients: A Case Series with three different brands

INTRODUCTION

Fracture of stems in primary total hip arthroplasty is a known complication and has been attributed to varus positioning, excessive weight of the patient, resorption of the femoral calcar and failure of the cement mantle. Fractures in uncemented revision femoral stems are rare and are attributed to reduction in proximal support either in the form of bone loss or an extended trochanteric osteotomy [ETO] against a distally well- fixed stem. Also, undersized stems and high BMI to increase the risk of stem fracture.

CASE REPORT

We report 3 cases of uncemented revision stem fractures. Case 1 is a 77 year old male, Case 2 is a 71- year-old female, case 3 an 82-year-old male. All three patients had significant proximal femoral osteolysis. All three had an extended trochanteric osteotomy for the revision surgery. The hips had remained in-situ for 4, 2 and 5 years respectively prior to fracture.

CONCLUSION

When planning complex revision cases involving long uncemented stems, attention should be given to the above-mentioned variables. ETO non-union and proximal bone loss play an important role in stem fractures. Stem failure can occur irrespective of the make, and factors such as adequate stem size and good diaphyseal fit are non negotiable.

Rupture of Extensively Porous Coated Stems. - A Case Series of 2 Patients

Introduction:

Mechanical failure of femoral stems of revision hip arthroplasty has been rarely reported. In the current study, the cause of two stem fractures, which occurred in vivo, was analysed with use of clinical and radiological data, and the functional result after revision is presented.

Case Report:

Two patients, A 70-year-old male and a 73-year-old female, both of Mediterranean ethnic, and both patients underwent a revision total hip replacement to an uncemmented extensively porous coated stem. Both stems suffered an implant fatigue in vivo at three years and at two years follow-up respectively.

Conclusion:

Revision total hip arthroplasty is a procedure that will be performed more often the following years due to aging of population. Any orthopaedic surgeon performing hip surgery should be aware of the risk factors that can lead to total hip arthroplasty failure. In the analysed cases we can learn that the main factors related to this failure included the use of a small size stem (inferior to 14mm), an inadequate proximal osseous support because of trochanteric osteotomy, and a reduced preoperative bone stock. Although the use of cables has not been stated as a predisposing factor, we consider that they could also play a role in the development of this rare complication.

Fatigue fracture in dual modular revision total hip arthroplasty stems: failure analysis and computed tomography diagnostics in two cases

We report on two patients with fracture of a modular, tapered and distally fixed, uncemented titanium revision hip stem, not previously described. A failure analysis revealed that the cause of the fractures was the development of fatigue cracks in the mid-stem cobalt-chromium modular junction ending in corrosion-fatigue failure. No material defects or stress risers were found in any of the implants. The diameter of the mid-stem modular junction might be undersized for use in heavy and active patients. We also report a new way of detecting an undisplaced fracture at the modular junction, using the scout image from a computed tomography (CT) scan; a technique that can be used when plain radiographs are inconclusive.