Cemented Hip Research Articles

Cemented Hip Designs are a Reasonable Option in Young Patients

BackgroundYoung patients with degenerative cartilage disease of the hip remain a challenge for the orthopaedic surgeon. Different treatment options are available of which uncemented hips are the most popular owing to long-term concerns about cemented implants. As an alternative, we have used a cemented hip design in combination with bone impaction grafting in patients with acetabular defects.Questions/purposesWe therefore determined the survival rates and radiological failures of cemented THA in patients younger than 30 years and reported clinical scores, complications and current state of the revised THAs.MethodsWe retrospectively reviewed all 48 patients (69 hips) younger than 30 years at the time of surgery who had a primary cemented THA performed between 1988 and 2004. Acetabular defects were reconstructed using bone impaction grafting in 29 hips. Mean age at surgery was 24.6 years (range, 16–29 years). Revisions were documented, radiographs were analyzed, and the Kaplan-Meier method was used to determine survival for different end points. No patient was lost to followup, three patients (four hips) had died. Minimum followup was 2 years (mean, 8.4 years; range, 2–18 years).ResultsEight hips were revised (three for infection and five for aseptic loosening) and one hip dislocated for which open reduction was necessary. One additional cup was considered a radiographic failure. The 10-year survival was 83% (95% confidence interval, 69%–92%) with revision for any reason as the end point and 90% (95% confidence interval, 77%–96%) with revision for aseptic loosening.ConclusionsWe found a high survival rate of these cemented THA in young patients. In young patients with acetabular bone defects we recommend reconstruction using cemented implants with bone impaction grafting.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Comparative Finite Element Analysis of the Debonding Process in Different Concepts of Cemented Hip Implants

Damage accumulation in the cement mantle and debonding of the bone-cement interface are basic events that contribute to the long-term failure of cemented hip reconstructions. In this work, a numerical study with these two process coupled is presented. Previously uniform bone-cement interface mechanical properties were only considered. In this work, a new approach assuming nonuniform and random bone-cement interface mechanical properties was applied to investigate its effect on cement degradation. This methodology was also applied to simulate and compare the degradation process of the cement and bone-cement interface in three different concepts of design: Exeter, Charnley, and ABG II stems. Nonuniform and random mechanical properties of the bone-cement interface implied a simulation closer to reality. The predicted results showed that the cement deterioration and bone-cement interface debonding is different for each implant depending on the stem geometry. Lower cement deterioration was obtained for the Charnley stem and lower bone-cement interface debonding was predicted for the Exeter stem, while the highest deterioration (cement and bone-cement interface) was produced for the ABG II stem.

Modified Harrington reconstruction for advanced periacetabular metastatic disease

Destructive metastatic lesions about the acetabulum result in pain and functional limitations. We assessed whether periacetabular reconstruction (PAR) improves quality of life by examining outcome measures of pain, function, and mobility. Thirty-seven patients with a mean follow-up of 23.6 months (range, 0.5-112 months) were retrospectively reviewed. All patients underwent modified Harrington reconstruction with periacetabular screws, cement, and total hip arthroplasty. The mean preoperative MSTS score of 14 (47%, 14/30) improved to 20 (67%, 20/30) after the procedure. Thirty-five patients who were alive 1 month after the procedure were reviewed for outcome. Postoperatively, patients reported a significant improvement in pain (P < 0.0001), mobility (P < 0.0385), and function (P < 0.0186). Kaplan-Meier survivorship curves showed 59% implant- and 55% patient survival at 2 years; and 49% implant- and 39% patient survival at 5 years. Complications included infection (16%, 6/37) and instability (16%, 6/37). Our experience with PAR has shown good results with improved postoperative functional scores. Implants will generally exceed life expectancy and are an option to restore quality of life.

Nondestructive evaluation of bone cement and bone cement/metal interface failure

To quantify the failure mechanisms related to the loosening of cemented hip joint replacements, novel techniques, capable of monitoring, nondestructively, the initiation and progression of failure during in vitro fatigue tests, were employed. Fatigue testing of model cement and cement-stem test pieces was monitored using acoustic emission (AE) sensors. Once damage was detected, an ultrasonic imaging system was used to obtain an image of the damage site and to measure the stiffness of the affected region. This method of examination provided a detailed insight into the internal crack propagation and delamination patterns. Initial work was conducted on bulk cement specimens subjected to bending and tension. The second stage of the work examined a model stem-cement interface under tensile opening loading conditions. A novel ultrasonic technique was used to measure the bond quality at the cement-metal interface. Progressive delamination was identified over time, and the AE technique was able to identify critical areas of delamination before they could be identified conclusively by ultrasonic imaging. The work has demonstrated the potential of the AE technique as a tool for the preclinical assessment of total hip replacements.

Novel methods to study functional loading micromechanics at the stem–cement and cement–bone interface in cemented femoral hip replacements

We have developed a technique to directly observe the micromechanics of the stem–cement and cement–bone interfaces of cemented femoral stems under physiologically relevant loading conditions. Thick transverse sections of a stem–cement–femur construct were fixed to the base of a test frame. Ante- and retro-verting torques were applied to the femoral stem by screwing the stem (via a pair of through holes) to an axle, which was turned using a lever arm actuated by the test frame cross-head. The surface of each transverse section was serially digitally imaged during loading. The displacements of the stem, cement and bone were determined using digital image correlation. These data were then used to calculate the relative displacements across the interfaces. This method provides a path to more thorough understanding of load-transfer from femoral stem to femur.

A technique for the fabrication of a reinforced moulded articulating cement spacer in two-stage revision total hip arthroplasty

We describe an inexpensive method of producing a reinforced articulating cement spacer using a commercially available hip cement mould. We have a cohort of 15 consecutive patients in whom this novel cement spacer has been used. All patients were able to at least partially weight bear and none of the spacers fractured. Thirteen have been explanted at second stage operation after a minimum of eight weeks in situ. Two patients have been unable to undergo a second stage due to unrelated death and medical problems precluding further surgery. The articulating cement spacer described is produced using a technique that is simple, reproducible and allows a reinforced spacer to be created inexpensively without the need for special equipment.

Does Femoral Component Loosening Predispose to Femoral Fracture?: An In Vitro Comparison of Cemented Hips

The incidence of femur fracture around total hip arthroplasties continues to increase at substantial cost to society. These fractures are frequently associated with a loose femoral component. Consequently, we sought to test whether femoral component loosening predisposes to periprosthetic femoral fracture. Because many periprosthetic femoral fractures are spiral in nature, we evaluated the torsional characteristics of the implanted femur in which the only design variable was instability of the femoral component. We used synthetic (polyurethane) (n = 15) and paired cadaveric femora (n = 10) with specimens divided into two groups: well-fixed and loose cemented stems. Each specimen was tested mechanically in internal rotation until failure. For the synthetic specimens, torque to failure was reduced by 38%, whereas stiffness was decreased 54% for the loose group compared with the well-fixed group. For the cadaveric specimens, torque to failure was reduced by 58%, whereas stiffness decreased 70% for the loose group compared with the well-fixed group. Fracture patterns were similar between synthetic and cadaveric femora with a proximal spiral pattern in loose specimens and more distal fracture patterns with well-fixed stems. Based on our data, patients with loosened femoral components are at risk for fracture at a substantially lower torque than those with well-fixed components.

The influence of cement mantle thickness and stem geometry on fatigue damage in two different cemented hip femoral prostheses

Experimental models can be used for pre-clinical testing of cemented and other type of hip replacements. Total hip replacement (THR) failure scenarios include, among others, cement damage accumulation and the assessment of accurate stress and strain magnitudes at the cement mantle interfaces (stem-cement and cement-bone) can be used to predict mechanical failure. The aseptic loosening scenario in cemented hip replacements is currently not fully understood, and methods of evaluating medical devices must be developed to improve clinical performance. Different results and conclusions concerning the cement micro-cracking mechanism have been reported. The aim of this study was to verify the in vitro behavior of two cemented femoral stems with respect to fatigue crack formation. Fatigue crack damage was assessed at the medial, lateral, anterior and posterior sides of the Lubinus SPII and Charnley stems. All stems were loaded and tested in stair climbing fatigue loading during one million cycles at 2 Hz. After the experiments each implanted synthetic femur was sectioned and analyzed. We observed more damage (cracks per area) for the Lubinus SPII stem, mainly on the proximal part of the cement mantle. The micro-cracking formation initiated in the stem–cement interface and grew towards the direction of cortical bone of the femur. Overall, the cement–bone interface seems to be crucial for the success of the hip replacement. The Charnley stem provoked more damage on the cement–bone interface. A failure index (maximum length of crack/maximum thickness of cement) considered was higher for the cement–stem interface of the Lubinus SPII stem. For a cement mantle thickness higher than 5 mm, cracking initiated at the cement–bone interface and depended on the opening canal process (reaming procedure and instrumentation). The analysis also showed that fatigue-induced damage on the cement mantle, increasing proximally, and depended on the axial position of the stem. The cement thickness is an important factor for the success of THR and this study evidenced that cement thickness higher than 2 mm apparently does not affect the mechanical behavior of the cement mantel and induce more crack formation on the cement–bone interface.

Furlong Hydroxyapatite-Coated Hip Prosthesis vs the Charnley Cemented Hip Prosthesis

We report the results of a prospective trial comparing uncemented Furlong hydroxyapatite-coated total hip arthroplasty and cemented Charnley total hip arthroplasty. One hundred ninety-one patients were allocated into 2 groups depending on their year of birth. One group received a Furlong hydroxyapatite-coated total hip arthroplasty and the other group received a cemented Charnley total hip arthroplasty. At a mean follow-up of 14 years (12-16 years), Harris hip scores showed no difference between the 2 groups. The longitudinal multilevel model analysis shows that the mean slope of the change in the Harris hip score was −0.02 for the Furlong group and −0.05 for the Charnley group; the difference is 0.03 ( P = .002). The survival analysis using Kaplan-Meier regression analysis (the log-rank test λ 2 1 = 0.031, P = .58) does not show a significant difference between the 2 groups. Overall survival was 93.6% in the Furlong group and 94.8% in the Charnley group.

The Vascular Network in the Femoral Head and Neck After Hip Resurfacing

The purpose of this study was to determine whether femoral neck fracture after cemented resurfacing hip arthroplasty (RHA) arises from intraosseous vascularity around the femoral head-neck junction. We implanted a replica of the femoral head component into osteoarthritic femoral heads and compared the intraosseous vascularity network between the femoral heads with and without the RHA procedure using microangiography through a retinacular artery with micro–computed tomography. Our results showed no significant difference in the vascularity around the femoral head-neck junction between the groups with and without the RHA procedure. These results suggest that deterioration of the intraosseous vascular network around the head-neck junction after RHA was not severe enough to induce complete avascularity.

Cemented total hip replacement for primary osteoarthritis in patients aged 55 years or older

We have analysed from the Finnish Arthroplasty Register the long-term survivorship of the 12 most commonly-used cemented implants between 1980 and 2005 in patients aged 55 years or older with osteoarthritis. Only two designs of femoral component, the Exeter Universal and the Müller Straight femoral component had a survivorship of over 95% at ten years with revision for aseptic loosening as the endpoint. At 15 years of the femoral and acetabular component combinations, only the Exeter Universal/Exeter All-poly implant had a survival rate of over 90% with revision for aseptic loosening as the endpoint. In the subgroup of patients aged between 55 and 64 years, survivorship overall was less than 90% at ten years. The variation in the long-term rates of survival of different cemented hip implants was considerable in patients aged 55 years or older. In those aged between 55 and 64 years, none of the cemented prostheses studied yielded excellent long-term survival rates (> or = 90% at 15 years).

Computer Simulation of Realistic Three-Dimensional Cemented Hip Arthroplasty: Thermal Osteonecrosis Analysis

Many current bone cements have proprietary minor ingredients that affect the chemical kinetics and heat transfer modeling of the exothermic reaction during bone cement polymerization. The geometry and the method of cooling or curing the bone cement can vary by application. We applied a complete numerical model using finite volume methods to investigate temperature history and thermal osteonecrosis analysis during and after bone cement polymerization for a commercial femoral component used in hip arthroplasty. Using a phenomenological kinetic model for energy generation, during bone cement exothermic reaction the effects of precooling and preheating parts of the femoral component before implantation were simulated. Numerical evidence shows that the temperature distribution along the bone depends upon the position of the stem with respect to the exterior bone boundary. Additionally, by precooling the stem, thermal osteonecrosis can be reduced in the bone through evidence of a thermal necrotic plane map of bone. Preheating the stem to above body temperature produces minimal thermal damage of the bone due to limited exposure time.

Detection of Right Heart Emboli by Transesophageal Echocardiography in Cement Implantation Syndrome in an Elderly Patient

Femoral fractures are common and lethal among elderly patients. The elderly suffer more perioperative risks because of their complicated medical conditions and poor physical reserves. During cemented arthroplasty surgery in the elderly, unstable hemodynamic changes are frequently noted when the cement and prosthesis are inserted. Transesophageal echocardiography (TEE) allows rapid perioperative diagnosis and management of hemodynamic changes. We report an elderly patient with paroxysmal atrial fibrillation, in whom a huge serpentine embolus was noted by TEE. Although cardiovascular collapse was encountered during cemented hip arthroplasty surgery, the patient was successfully resuscitated and the related perioperative risk was managed by TEE application.

Design aspects involved in a cemented THA stem failure case

Fatigue failure of total hip arthroplasty stem is today a rare case due to improvements of the technique along many decades. However, any case of stem fracture should be treated with attention due to the problems that can result in the revision for the patient. The most common cause of stem fracture is the proximal aseptic loosening. This scenario is reproduced in endurance test protocol ISO 7206-4 and should be applied for all design changes to prevent fracture of the stem even in the event of mechanical or biological problem that result in the aseptic loosening. This paper presents a cemented hip stem failure analysis. The study consisted of fracture analysis, material characterization, numerical simulation of the stem under the conditions of the endurance test, as well as fatigue tests of the ASTM F 745 stainless steel. The failure, in the mechanical aspect, is associated to the use of the cast stainless steel and could have been predicted through testing prior commercialization. Some design aspects are discussed. The use of cylindrical distal portion, matt surface and collar can reduce the stability in a loosened cemented hip stem.

Cyclic Loading of Periprosthetic Fracture Fixation Constructs

Femur fractures are a common complication of hip arthroplasty. When the stem is well fixed, fracture fixation is the preferred treatment option. Numerous fixation methods have been advocated, using plates or allograft struts. Vancouver type B1 periprosthetic femur fractures were created distal to a cemented hip stem in 15 third-generation composite femurs. The fractures were fixed with (1) a nonlocking plate and allograft strut, (2) a locking plate and allograft strut, or (3) a locking plate alone. The struts were fixed with cables. After fixation, the constructs underwent cyclic loading for 100,000 cycles. Stiffness of the constructs was determined during bending, torsion, and axial compression before and after cyclic loading. Load to failure was also determined. Overall, cyclic loading had little effect on the mechanical properties of these constructs. The two constructs with allografts were significantly stiffer in bending than the construct consisting of only a locking plate. There were no significant differences in axial or torsional stiffness between the constructs. Load to failure of the two constructs with allografts was significantly greater than the locking plate alone. Allograft strut-plate constructs are stiffer in bending and have a higher load to failure than a stand-alone locking plate. When an allograft plate construct is chosen, locking screw seemed to provide no mechanical advantage. All three constructs tested retained their mechanical characteristics after 100,000 cycles of loading. Our initial concern that the cables fixing the allograft strut would loosen appears unfounded.

Effect of a constructive change in the Charnley total hip endoprosthesis on its permanent stability in the bone

Because of long experiences with cemented hip joint prostheses and the simple geometric form of this joint shape and material of those prostheses are nearly established. Therefore, success of different systems is measured by duration of stabile fixation in the bone. A minor modification of the acetabular cup is able to improve this duration of stability. The cup has a additional central cone which will be wedged firmly in a centering hole, drilled in the acetabulum. In a longtime follow-up study of 1004 operated patients - medium observation time 7.8 years - the cup loosening rates are only 2.6%. The biomechanical basis of the value of the central cone is discussed.

Survival time of loosened cemented hip joint prosthesis

With the help of survival curves we analysed in 111 aseptically loosened endoprostheses of the hip the function of the implants. We found a mediate rate of 6.04 years for the total survival time. We discussed two peaks after 2 years and between the 5. and 8. year after the implantation. There was a reduction of the survival time in the upper age and in the right side of the implantation. The second implantation had a worse prognosis compared with the first implantation (medial rate of 2.38 to 6.6 years). Important causes for the loosening were an enlarged angle of the hip socket and a varus position of the stem. But the survival curves showed in connection with these factors no statistical significance. We found a reduction of the survival time in the cases with no complete boundary of the bone cement in the proximal part of the stem.

Cognitive function and cerebral emboli after primary hip arthroplasty

Transcranial Doppler ultrasound has been used to detect cerebral emboli after hip arthroplasty. The cognitive effects of these embolic events are unclear. The aim of this study was to assess cognitive change after primary cemented hip arthroplasty using a range of neuropsychological tests and to measure intraoperative cerebral embolic load. Twenty primary cemented total hip arthroplasties underwent a series of cognitive tests before and at four days after surgery. A range of validated tests assessed: global cognitive function; verbal fluency and speed; immediate and delayed memory recall; attention and mental processing speeds. Intra-operative transcranial Doppler ultrasound monitoring of the middle cerebral artery for embolic signals was also performed. A one-sample Wilcoxon signed-rank test compared median cognitive results post-pre surgery and a Mann-Whitney U test established if there was a cognitive difference between those patients who had detectable cerebral emboli and those who did not. Scatter plot graphs were also used to establish any correlation between the embolic load and clinical cognitive dysfunction. A significant (p<0.01) difference was noted in specific tests assessing mental processing speed, visual searching and sustained and divided attention following surgery. Intra-operative cerebral embolic signals were detected in 11 out of 20 patients and the majority occurred with femoral component cementation and hip reduction. There was no difference in cognitive dysfunction between those patients who had detectable cerebral embolic signals and those who did not and there appeared to be no direct correlation between the size of the embolic load and the level of cognitive dysfunction.

Cognitive function and cerebral emboli after primary hip arthroplasty

Transcranial Doppler ultrasound has been used to detect cerebral emboli after hip arthroplasty. The cognitive effects of these embolic events are unclear. The aim of this study was to assess cognitive change after primary cemented hip arthroplasty using a range of neuropsychological tests and to measure intraoperative cerebral embolic load. Twenty primary cemented total hip arthroplasties underwent a series of cognitive tests before and at four days after surgery. A range of validated tests assessed: global cognitive function; verbal fluency and speed; immediate and delayed memory recall; attention and mental processing speeds. Intra-operative transcranial Doppler ultrasound monitoring of the middle cerebral artery for embolic signals was also performed. A one-sample Wilcoxon signed-rank test compared median cognitive results post-pre surgery and a Mann-Whitney U test established if there was a cognitive difference between those patients who had detectable cerebral emboli and those who did not. Scatter plot graphs were also used to establish any correlation between the embolic load and clinical cognitive dysfunction. A significant (p<0.01) difference was noted in specific tests assessing mental processing speed, visual searching and sustained and divided attention following surgery. Intra-operative cerebral embolic signals were detected in 11 out of 20 patients and the majority occurred with femoral component cementation and hip reduction. There was no difference in cognitive dysfunction between those patients who had detectable cerebral embolic signals and those who did not and there appeared to be no direct correlation between the size of the embolic load and the level of cognitive dysfunction.

Extensively coated revision stems in proximally deficient femur: Early results in 15 patients

Background:Hip replacement following failed internal fixation (dynamic hip screw for intertrochanteric fractures) or previous hip arthroplasty presents a major surgical challenge. Proximal fitting revision stems do not achieve adequate fixation. Distal fixation with long-stemmed extensively coated cementless implants (like the Solution™ system) affords a suitable solution. We present our early results of 15 patients treated with extensively coated cementless revision stems.Materials and Methods:Fifteen patients with severely compromised proximal femora following either failed hip arthroplasty or failed internal fixation (dynamic hip screw fixation for intertrochanteric fractures) were operated by the senior author over a two-year period. Eight patients had aseptic loosening of their femoral stems following cemented hip replacements, with severe thinning of their proximal cortices and impending stress fractures. Seven had secondary hip arthritis following failure of long implants for comminuted intertrochanteric or subtrochanteric femoral fractures. All patients were treated by removal of implant (cemented stems/DHS implants) and insertion of long-stemmed extensively coated cementless revision (‘Solution™ DePuy, Warsaw (IN), US’) stems along with press-fit acetabular component (Duraloc Cup, DePuy, Warsaw (IN), US). All eight hip revisions needed extended trochanteric osteotomies.Results:All patients were primarily kept in bed on physiotherapy for six weeks and then gradually progressed to weight-bearing walking over the next six to eight weeks. The Harris Hip Scores and patient satisfaction were used for final evaluation. We achieved good results in the short term studied. In our first three patients (all following failed cemented total hip replacements), we resorted to cerclage wiring to hold osteotomised segments (done to facilitate stem removal). The subsequent 12 proceeded without the need for cerclage wiring. One patient had a intraoperative severe comminuted fracture extending into the supracondylar region while hammering in the stem. Post cerclage wiring, she was put on a long knee brace and her mobilization was delayed to 12 weeks.Conclusions:The extensively coated cementless (‘Solution™’) femoral stem provides a reasonable ‘solution’ to the deficient femur in hip revision. The proximal femoral deficiences can be relatively easily bypassed and distal fixation can be achieved with this stem. Extreme care needs to be taken to avoid fractures and penetration of the femoral shaft, which can, however, be managed by cerclage wiring. Principles of a successful outcome include preservation of the functional continuity of the abduction apparatus, care to recognize and prevent distal extension of fracture while inserting the stem (preemptive cerclage wiring) and supervised rehabilitation.