Free «Bone prothesis» Essay Sample


Osteoporosis is an illness typified by low bone mass as well as structural weakening of bone tissues resulting into bone vulnerability (Tosteson &Hammond, 2002). Osteoporosis connected to fractures creates chief morbidity, which are very common in older people (Lips & Schoor, 2002). Once a year in the U.S, approximately 1.5m fractures related to Osteoporosis happen and this figure is anticipated to rise roughly by fifty per cent by the year 2025 (Burge et al, 2007).  There are three common main risk facets for Osteoporosis and this may include, ages, inactivity and women who are postmenopausal and having little body weight. Hip fractures are commonly fractures of the Proximal Femur and are accountable for the most severe results of Osteoporosis (Steinberg, Blumberg, & Dekel, 2005). Individuals may decrease fractures risk through sustaining bone strengths and holding up swift bone remodelling. To attain these objectives, people having Diabetes as well as elderly persons employ physical exercise regimes to decrease the risk for Osteoporosis as well as fractures (Rizzoli et al, 2009). Nevertheless, age, inactivity and any other frailty can prevent the best possible partaking in exercises regime planned for Osteoporosis patients (Kenny et al, 2009).

Iwamoto et al (2005) argues that it’s the mechanical stimulus within the type of vibrations stimulus which travels from the single of the foot up through the skeleton in Anabolic to bone. It is worth noting that the recent vibration machines have illustrated beneficial raises in bone mineral density (BMD) (Semler, 2008), improvements in posture, balance and gait as well as skin blood flow and positive impact on muscle activities, strength as well as exercises result (Rees, Murphy, Watsford & 2008).  Common to recent vibration apparatus is the employ of sole fixed vibration frequency as well as dislodgment height. The vibrations parameter may be fixed as well as changed at a diverse stage prior to the start of any session (Gnudi, 2002). 

Femur Bone

The femur bone is also known as thigh bone and the longest bone of the human being skeleton that is situated amid the knee and hip bone. Femur bone is one of the strongest bones in the human’s skeletons, and its main function is to support the body’s weight as well as allowing motion of the lower extremity (Steinberg, Blumberg & Dekel, 2005). The femur bone is in each leg. This bone forms part of the hip and knee joint. In addition, this bone comprises of 4 parts, which includes “the head, greater tro-chanter, lesser tro-chanter and the lower extremity”. It is clear that the femur plays a vital role in walking as well as running (Steinberg, Blumberg & Dekel, 2005).

Broken Femur Bone

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Femur fractures differ very much depending on the forces which causes the fracture. The pieces of bone can align accurately or even be out of alignment and the breakage may be close or open. Practitioners explain fractures to each other using categorization systems, and this may be classified depending on: 

  • The location of the fracture
  • The pattern of the fracture
  • Whether the muscles and skins above the bone is torn by the damage

These femur fractures are commonly caused by car accidents and falls from a height. Patients can also have bone which is weakened by Osteoporosis, Tumour and infections, and these conditions may lead to Pathologic femur (Tosteson, & Hammond, 2002).  Femur fractures are usually grouped into 3 wide categories:

  • Proximal Femur Fractures- This is also referred to as Hip Fractures which involve the upper most part of the thigh bone only adjoining to the Hip Joint.
  • Femoral Shaft Fracture: This severe damage which usually takes place in high speed cars collision as well as significant fall; these frequently major injuries may be experienced by the patients.  The Femoral Fractures treatments are almost at all times with surgery and the common process is to insert a metal rod down the centre of the thigh bone known as Intra-medullary rod (Charnley, 2004). This process reconnects the two ends of the bone as well as the rod is protected in place with screw both below and above the fracture.  The intra-medullary rod usually stays in the bone for the life of the patient, but may be removed if it causes pain or any other issues.

Other less commonly applied treatments of Femur Fractures include a plate and screw or even an exterior fixation. These treatments selections may have to be applied if an intra-medullary rod cannot be used for some reason. In certain patients, depending on the fracture type and connected damages, an intra-meduallary rod may not be an option; in these cases, one of the other treatments will be selected (Bateman, 2004).           

Supra-condylar Femur Fractures: This is extraordinary injuries to the Femur only above the joints of knee and has to be treated with the cartilage hurt in mind.  Patients those who maintain a Supra-Condylar Femur Fractures are normally at high peril of having arthritis of the knee later in their life.  Supra-Condylar Femur Fractures are mostly in patients who are having serious osteoporosis as well as in patients who previously had suffered replacement of the entire knee surgery (Giliberty, 2003). These categories of patients whom their bone is just above the joint of the knee may become more fragile than in normal patients, and as a result, more prone to fractures. Nevertheless, patients may also maintain a Supra-Condylar Femur Fractures following high force damages. The treatments of a Supra-Condylar Femur Fractures are greatly changeable as it may employ a cast or even brace exterior fixation, plate, screws or Intra-medullary rod (Bogaerts, 2007). There are a lot of disparities to these fractures that have an effect on the most excellent method for fixation of the fractures (Giliberty, 2003).

Short Stem Prosthesis

The recent concepts of Proximal Femoral fixation in Hips Arthroplasty may be categorized into 3 groups; that is Surface Replacement concept, femoral neck prostheses and short stems prosthesis. Between 1999-2004, more than five hundred short stems prosthesis (Mayoa) were implanted at the Orthopaedic Department (Horowitz, 2006) to scrutinize the early functional consequences, which was a potential randomized research that was carried out to compare forty cement-less Short Stems Prostheses (Mayoa 1) with forty cement-less anatomical principles Stem Prosthesis (ABGa 2) implanted in patients with unilateral hips Osteoarthritis (Lancho, 2006).  Genders, age’s diagnosis, and body mass index illustrated no important disparity amid both sets.  In all patients, an uncemented ace-tabular press fit cup was applied and the implantations were carried out by four Orthopaedic consultants. A standardized anterolateral approach to the Hips was applied in all cases. In the Short Stem set, the Femoral-neck was conserved to accomplish a multipoint fixation of the double tapered stem in the Inter-trochanteric area (Da Silva et al, 2008).   

Patients were followed clinically as well as radio-graphically at three, six and twelve months post-operatively. Disparities amid both categories were tested using t-test of the students, no specific complications occurred neither during surgery nor during the follow up (FU), and no patients were lost for Follow Up. The radio-graphic Follow Up illustrated an accurate implant position in every case.  About the Harris Hips Score (HHS), a statistically important variation %u02C20.01 was established at three months (Cardinale & Rittweger, 2006). The Harris Hips Score for the Short Stem category averaged at 93.87 points that is ranging from sixty to one hundred points, while for the ABG set averaged at 87.02 points; that is sixty to one hundred points. Preoperatively at six and twelve months, no statistically major disparity may be found amid both categories. In this study of Short Stem Prosthesis, the patients who are having Short Stem Prosthesis returned faster to work as well as normal day to day duties. Therefore, as a researcher, I attribute that this needs be the Femoral-Neck approach with no engagement of the superior Trochanter as well as the abductor muscles (Bogaerts et al, 2007). Having its high-quality functional outcomes as well as its bone saving concept, the Short Stem is a pretty design especially for the younger patients.  

Medium Stem Prosthesis

The medium stem prosthesis is more regarded as implant of first selection in Coxartrosis, particularly in younger patients. In spite of promising medium terms result to the long term FU researches are yet missing. Medium stemmed femoral implant is typified by a Metephyseal Osseointegration as well as injuries distribution (Lip & Schoor, 2005). Nevertheless, a decreased stress protective of the proximal femur is hypothesized and in a number of researches have already proved. There is histological proof that Osteonecrosis (ON) of the femoral head can engage not just the Intra-capital area but also the femoral neck as well as Metaphyseal region (Gnudi et al, 2002). This may lead to higher rates of aseptic loosening of medium stemmed implants.

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From the year 2002 to 2004, the patients including two females, nineteen males with averaged age of forty five years and mean BMI of twenty seven, having secondary Coxarthrosis subsequent to Ostenercrosis implantations of twenty six Mayo Conseverative Hips were carried out (Charnley, 2004).  Post-operatively every patient was mobilized with small weight bearing, by use of special created Wristing Software, Longitudinal stemmed migration as well as Varus-Vaalgus femoral stemmed alignments were scrutinized digitally in Anteroposterior X-ray taken right away following surgery as well as in standing AP radio-graphs following 8.2 months plus on mean after 7.9 months years a total of sixteen patients (Steinberg et al, 2005). 

The occurrence Peri-prosthetic radiolucent lines were capture within the Anter-oposterior X-rays and allocated to the Gruen Zone as well as a DEXA scans were carried out (Burge et al, 2007). The X-rays of the matched control group with implantation of MayoTM medium stemmed prosthesis within the basic Caxarthrosis were analysed through the similar technique. In every patient, Harris Hip Score (HHS) was achieved pre-operatively as well as post-operatively (Kenny et al, 2009). There are no noteworthy migrations of the MayoTM (Mishra, 1997) prosthesis in the research and mange categories during post-operative FU paired t-test p = 0 .13 and 0.69 respectively. In the 6 of twenty six Mayo TM Stems, twelve Radiolucent Lines (RL) of the Mayo TM were scrutinized (Walker et al, 1999). The control category illustrated at 10 of thirty Mayo TM Stems seventeen Radiolucent Lines (RL). The disparities between the categories were not statistically disparity; that is Chi-Square test for the total number of RL: %u04B22   = 0.001, p = 1.0 and %u04B22 = 0.006, p=0.79 for the number of Mayo TM Stems with RL (Malchau et al, 1997).

The DEXA scans illustrated a little higher bone mineral density (BMD) in Gruen Zone three and four compared with control categories, research category (Rees et al, 2008).  In the research category, the post-operative HHS were 93.5 that is standard deviation of 5.6 compared to 94.2 with standard deviation of 6.9 within the manage category “t-test, p = 0.63” (Rubin et al, 2002).  In the medium term course, there were no increased migrations that may be proven for Mayo TM medium stem THA within patients having Osteonecrosis of the femoral head, and due to the lack of present disparities within the happenings of Radiolucent Lines as well as same outcomes in the DEXA scans an unimpaired Osseo-integration of the Mayo TM stem is supposed (Learmonth et al, 1995). Consequently, it is concluded that Mayo TM conservative Hip may be regarded as an alternative for operative treatment of Osteonecrosis of the femoral head (Sherry et al, 2003).     

Long Stem Prosthesis

The extensive loss of the bone increases formidable challenges in entire Hip revision, the concentration here is to assess the consequences of reconstruction applying the cemented Long Stem as well as substantial structural allograft implanted in a filleted Proximal Femur with and without the use of a Trochanteric claw plate (Boonen, 2008).  Between year 1988 and 2001, forty four revisions were carried in forty two patients, following a Transtrochanteric approach, the Femur was cut longitudinally.  Long cemented charnley type prosthesis was used and flaps of the residual Femur were folded around the allograft. The superior Trochanter was reinserted with wires in all revision and with both wire and a claw plate in twenty revisions (Rubin et al, 2002). The average of this was 7.15 years ranging from three to sixteen; there were 7 patients who died, while 4 lost to follow up. This following up went beyond 5 years in thirty four patients. The main complications were non-union of the bigger Trochanter that took place in twenty five cases. 6 displacements, 1 recurrence of infection, 2 mechanical loosening, as well as 2fractures just below the stem also were recorded. The utilization of a Trochanteric claw plate enhanced final Hip steadiness drastically, and even in patients having non-union. Reconstruction of Femoral with a substantial structural allograft is dependable as well as long standing and severe complications as well as long term re-sorption are unusual (Gnudi et al, 2002). Thus full utilization of Trochanteric Claw Plate drastically advances Final Hip Steadiness.   

The wide-ranging loss of bone within the Proximal Femur remains a hard challenge in patient who needs Hip Revision Surgery. Implants loosening as well as the attendant shedding of wear particles are closely associated with progressive bone loss that may result into wide-ranging defects. A number of choices are available for controlling widespread loss of bone within the Proximal Femur. An un-cemented enormous stem fixed by press fit or even distal bolting screws is extensively applied, with hopeful outcomes (Semler et al, 2008).  When bone stockpile have to be reinstated, implications of grafting appears to offer superior outcomes. Injuries to the Proximal Femoral Metaphysis can preclude the application of these methods, nevertheless leaving enormous reconstruction of allograft as the only solution. This study has assessed the Short or Medium term outcomes of immense reconstruction of allograft (Ree, Murphy & Watsford, 2008), on the foundation of the technical disparities, application of further sterilizations, diminutive sample sizes as well as pooling of patients who require cancer surgeries with patients suffering replacement of joint. A number of current series reported the outcomes with comparable methods and established high rates of poor steadiness because of Trochanteric non-unions (Rees, Murphy, & Watsford, 2008). 

Even though extensive progresses have been made within the improvement of cement-less entire Hip Arthroplasty (THA) in current years, several limitations remain. The implantation of the femoral constituent needs a bigger surface part of bone to be prepared (Learmonth, Grobler, Dall &, Jandera, 1995). Osteopenia because of non-physiological loading as well as stress defence, distal relocation of wear units from the joint space or even insufficient Stem fixation may raise the peril of aseptic loosening as well as subsidence of the stem (Dunbar, Kawamura, Murray, Bourne &, Rorabeck, 2001). The application of a firm femoral constituent can lead to Calcar atrophy as well as cortical losing ground; nevertheless, modern titanium alloy femoral constituents seem to decrease the peril of these stress shielding effects (Dunbar, 2001). Additionally, intense study endeavour has been directed as characterising post-operative thigh pain, a clinical limitation in THA which may range from immediate mild postoperative signs to serious disabling pain that needs revision surgery (Brown, Larson, Shen & Moskal, 2002). Micro-motion unfastening uneven pressure patterns or stem tip sclerosis appears to induce such pain in thighs.  In addition, the application of a long femoral stem raises the peril of pains in thigh because of impingement of the stem steps on the femoral cortex (Mishra, Skinner & Davidson, 1997), as well as guide correlations have been drawn amid pains in the thigh and raise the stem volume. The studies have also been carried out in ways to advance the restriction of conventional surgical methods in THA. A fewer invasive surgical methods can result into less pains within the early post-operative duration as well as advance the post-operative functional status  (Sherry, Egan, Warnke, Henderson, & Eslick,  2003) even though the scientific argument concerning better results of this method compared to the conventional surgical process is yet in progress.     

In order to deal with these limitations a fresh THA implant plans having shorter stem have been created some plans like the IPSIM, the Mayo conventional Hip or Santori Consumer Stem has been engaged in shortening much of the distal stem focusing on maximizing bone as well as tissues preservation. Besides, Anatomic short femoral prosthesis may decrease the potential for stress shielding within the femur via an extra physiological stress distribution towards femoral short stem (Gnudi al et, 2002).

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Proximal Load Transfer

In the year 1917, Koch (1917) suggested his models of the mechanic of the loading of the Hip that comprised a geometrical explanation of the femur as well as a computation of emphasized on inducing the loads which were supposed to take place during way of walking. Therefore, through correlating the stress patterns within the Trabecular bone with Wolfs (1986) concepts of bone formations. Koch argued that the tensile and compressive forces along the medical as well as lateral femoral surfaces (Learmonth , Grobler , Dall  &, Jandera, 1995). The femoral loading the better necks as well as proximal lateral ¾ of the femoral shaft were under tensile loading while the distal lateral as well as the whole medical femoral surfaces was under compression. Koch’s model was deemed as the definitive model of Hip biomechanics for the subsequently 70 years as well as served as a fundamental for the expansion of plan as well as validation of THA systems.  However, as Koch’s static model did not adequately concentrate on the function of soft tissues around the Hip joint (Fetto et al, 1995) developed advanced model. Through the inclusion of the iliotibial band as a static lateral tension bands along the lateral aspect of the lower limb, and argued that compressive loading is actually generated both laterally as well as medically throughout the femur distal to the greater Trochanteric apophysis during the unilateral support phase of way of walking (Mishra, Skinner & Davidson, 1997).

Further uniformity of this model was attained by bone morphology researches with cadaveric femora as well as femoral CT scans, revealing a noteworthy quantity of cortical bone mass at the lateral facet of the femur. Fetto et al (1995) concluded that the femoral constituent of THA prosthesis have to involve the proximal lateral femoral cortex as an extra part of assistance against subsidence to evade stress protective as well as succeeding loss of proximal femoral bone.    

Lateral Flare

Walker et al (1999) found out basic changes within the load transfer amid stem as well as bone when comparing contact forces amid femoral bone as well as measure length straight stems or stems with a lateral flare. The study illustrated that for a measure straight stem, loads are mostly transferred through the distal half of the stems. On the contrary, the interface contact emphasizes from a proximally fixed stem with a lateral flare illustrated that every of the loading from the prosthesis is shifted to the proximal femur (Williams, Penrose, and Hose, 2000). Furthermore, the magnitudes of the interface emphasizes as well as distal migration during the application of the load were both lower within the lateral flare stem. In addition, outcomes of the radiographic follow up from these study demonstrates that the Trabecular attachment onto the lateral flare offering indirect proof of load transfer in that area.  Leali et al (2002) reassessed radiographs from prime THAs with a lateral flare for axial migration as well as steadiness. The proximally fixed cement-less, femoral constituents illustrated the mean subsidence of 0.32mm after two years that remained below 1mm for the period of the twenty four to one hundred and four months FU. Leali et al (2002) contended that the proximal lateral flare offers important initial steadiness that has been demonstrated to be significant achieve long term steadiness through early bone in development. In addition, a dual energy X-ray densitometry research of stem with a lateral flare was carried out that explained the bone content was preserved at the baseline level or above throughout the FU duration of one year (Malchau, Wang, Karrholm &, Herberts, 1997). This was especially manifested within the proximal prosthesis support zones (Learmonth et al, 1995). Similarly, bone mineral density around the Santori customs short stem was significantly higher in zones one to seven when compared to other conventional cement-less implants on 3 years FU (Locho, 2006).

Finite Element Analysis of Implant

The Swanson, (1972) carried out two dimensional finite element analysis for figure implant; the finite element model was applied to establish the stress area at the implant, particularly within the Stem hinge interface. The blending stiffness for every angle of rotation may be computed to find out the variety of motions of the implant (Wilson, Sykes & Niranjan, 1993).

Modelling the Bones

So as to model the Anatomy of the joints of Metacarpophalangeal (MCP) correctly, bone ends demonstrating Metacarpals (Williams, Penrose, and Hose, 2000) as well as Proximal Phalanx were modelled around proximal plus distal stem of the implant respectively. These bones illustrate the Intramedullary Canal which constrains the Stem “in vivo”. The dimensions of these bines were not chosen to illustrate the true geometry of the implant as bones are stiffer as well as harder than the implant (Akagi, et al. 1994), hence unlikely to deform.  The bones were meshed applying PLAN 42 as the stresses performing on the bones were not examined. Bones Cancellous properties were applied for metacarpals as well as proximal Phalanx where Modulus of Young is 110 MPa plus Poisson’s ratio is 0.20 (Biddis, Bogoch, and Meguid, 2004). The bones were supposed to have elastic as well as isotropic material properties (Williams, et al, 2000).

The poisoning of the metacarpal stem of the implant was modelled allowing the proximal stem to slide in the medullary cavity (Lewisa &Alva, 1993). Flexible to rigid contact pairs were developed amid the metacarpal boned as well as proximal stem to allow sliding amid the stem plus metacarpal tunnel. Flexible to rigid contact pairs were also developed amid the distal stem of the implant as well as proximal phalanx (Lewis, & Alva, 1993). By convention, in flexible to rigid contact the target surface is always the rigid element and the contact surface is flexible element. In this model the bone was the target surface and the implant was the contact surfaces (Lewis, & Alva, 1993).

Materials and Methods

The finite element analysis in accepted theoretical methods applied within the solutions of engineering issues (Zienkiewics, 1989). This technique has also been applied in Bio-mechanical analysis dental structure (Tanne, Burstone & Sakuda, 1989). The techniques for the assessment of effects on stress around implant systems include Photo-elasticity, finite elements analysis as well as strain measurements (Learmonth et al, 1995). The finite element analysis provides benefits, including precise representation of multifaceted geometric, simple model modification, the internal state of stress plus other mechanical quantities. The solid modelling as well as finite elements analysis was carried out on personal computers, since it was hard to take geometries into account when jaw bone was modelled (Learmonth et al, 1995) modelling employed were made simpler in variety not affecting local stress analysis. Nevertheless, it offers the fundamental for a relative assessment of outcomes achieved from every analysis (Brown, Larson, Shen, & Moskal, 2002). According to Koch, (1917) the analyses in this study were carried out as follows, firstly, the implants shape, and based on a variety of kinds of commercially available implants to be chosen for analyses were plateau type, and this is model 1. The plateau with diminutive radius of curvature, and this model 2 while model 3 is where triangular thread screw type with “0/Æ7 mm” in screw pitch in accord with ISO rules (Koch, 1917). The fourth model is that square thread screw with 0 /Æ9 mm in screw pitch in accordance with ISO policies whereas the fifth model is that the square thread screw filled with small radius partially (Koch, 1917). The shapes mentioned above have equal maximum external diameters of four mile meters as well as the length of ten mil meters equally. Secondly, applying the above mentioned outcomes analysis were carried out on implant shapes having more effective stress distribution than that of other shapes for varying design parameters, like the width of thread end, the height of the thread for various load directions (Walker et al, 1999).  


This study demonstrated that the even though the Intertrochanteric fractures of Femur in a bit older patients are related with higher rates of humanity and morbidity but early under your own steam with full weights bearing subsequent to major long stem Bipolar Hemi-Arthroplasty considerably decreased the occurrence of a variety of post operative complications related with long standing immobilizations like Venous Thrombosis, forces, pressures sores as well as Pulmonary tricky situations. Therefore, according to my views the kick-off it may seem to be uniformly high quality consequences in both categories more elderly is the patients as well as the selection have to fall for Arthroplasty than Fixation. Thus, the practitioners must have knowledge on how to deal with various situations as well as patients having different fractures, and also patients are suppose to be educated on how to handle their joints.

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