CERAMIC TOTAL HIPS
Contents:
Outline of the ceramic total hip
Ceramic ball on polyethylene cup systems
Possible concerns with ceramic total hips
See also CERAMIC MATERIALS FOR CERAMIC TOTAL HIPS
What are the ceramic hips?:
The term "ceramic total hips" is sometimes used for two, widely different, models of total hip joints.
(Click on the icon for a full size picture)
The upper picture: The ceramic on ceramic total hips are true ceramic total hips
They have the ceramic cup that articulates with the ceramic ball component. Both components are made from alumina ceramic (aluminum oxide ceramic).
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The lower picture:
The ceramic-on-polyethylene total hips
have a ball component made from ceramic material that articulates against a polyethylene cup. The right term for these total hips is "ceramic-on-polyethylene total hips".
Why ceramic total hip?
In a ceramic total hip the ceramic ball moves inside the ceramic cup. This bearing combination produces (in laboratory tests) the lowest quantity of wear particles of all known combinations materials used for manufacture of total hip joints. This is so because the modern medical grade ceramic is very hard and scratch resistant material.
Volumes of wear particles produced by different bearing material combinations in total hip joints. (Heisel 2003).
Bars in the diagram show the annual production of wear particles in cubic millimeters. The metallic ball articulating on a polyethylene cup produces 57 cubic millimeters of polyethylene wear particles, whereas the ceramic ball articulating on the same polyethylene cup produces only 17 cubic millimeters of such particles. The lowest rate of wear particles, 0,04 cubic millimeters of ceramic wear particles annually produces the ceramic total hip.
Note that ceramic total hip produces (57/0.04)= 1425 times less wear particles than the metal on polyethylene total hip and (17/0.04) = 425 times less wear particles than the ceramic on polyethylene total hip.
(Click on the icon for a full size picture)
Moreover, laboratory studies also demonstrated that ceramic wear particles entice less cell reaction than polyethylene or metal particles produced by other total hip systems (Warashina 2003).
The current theory maintains that the risk of total hip joint failure is directly dependent on the volume of wear particles produced inside the total hip joint. The less wear particle production the less the risk of developing failure of the total hip.
From this viewpoint, (and based on laboratory results only), the ceramic total hip joints should have the lowest risk of loosening and failure. Look at the results of ceramic total hips.
Because physical activity increases the production of wear particles, the ceramic total hips should be especially suitable for young patients who are physically active and have a long active life before them.
During their long and physically active lifespan the young patients with ceramic total hips would produce the lowest volume of wear particles of all studied total hip systems.
Note please, that as yet there are no long-term results of modern ceramic total hips available to substantiate the laboratory results; this is so because the modern ceramic total hips came into use in 1995's.
3The outline of a ceramic-on-ceramic total hip joint
The modern ceramic hips have both the femoral ball and the cup components made from medical grade alumina ceramic. (For information about the material properties please see the chapter Ceramic for total joints)
The alumina ceramic is very hard. This fact has important consequences.
- First, the bone tissue cannot endure direct contact with the hard ceramic; thus the ceramic cup must be enshrouded in a metallic cover (sleeve) to prevent bone tissue from direct contact with ceramic material.
- Second, although alumina ceramic is very hard it is also very brittle if a blow strikes against a small area of its surface. The blow at the rim of a ceramic cup engages a very small area only and produces high stress concentration in the material. Such blow may chip off a small piece of the ceramic material and produce a thin fracture line. The edge of the modern ceramic cup must be thus protected against unintentional blows.
- Third, the ceramic ball is attached to the femoral stem through a metallic conus. This attachment produces stresses in the ball. The alumina made ball must have a certain minimal diameter (28 millimeters) to contain these stresses.
These conditions influence the construction of a modern ceramic total hip device.
The cup of the ceramic total hip is composed of at least two layers: The inner layer is the ceramic cup proper, also called ceramic liner, that articulates directly with the ceramic bal. The outer layer is a metallic sleeve (back-up) that is in direct contact with the bone tissue of the hip socket. The ceramic ball (B) is fixed to the metallic femoral stem through the Morse taper. The metallic cone of the taper is put into a hole in the ceramic ball under pressure. Such construction produces always stresses in the ceramic material (red arrows). (For details see the chapter Morse taper).
Picture: Outline of the modern ceramic-on-ceramic total hip joint
(Click on the icon for a full size picture)
The ceramic cups with extra protection against impingement
The construction of some modern ceramic total hip includes arrangements that will protect the edge of the ceramic cup against unintentional blows/strikes. These strikes may happen during surgery, when the surgeon puts the ceramic inlayer into its metallic back-up. Most often, however, occur these strikes during extreme hip movements and are called "impingements". See details on Impingement mechanism.
These modern ceramic cups are three-layered constructions. Their ceramic liner is placed in an additional protective sleeve at the factory.
Click on the icon for a full size picture
CeramicTH_Cup.jpg
Picture:(Click on the icon for a full size picture) The ceramic cup composed of three layers:
On the upper picture is Trident TH, Stryker model. It has a composite ceramic liner that was preassembled at factory ; the titanium overrides the ceramic cup's rim and thus protects it from impingements.
You see on the photography (and the schematic small cross section picture) the ceramic ball that articulates directly with the ceramic inlay. Around the ceramic inlay is firmly attached
a metallic sleeve (intermediate layer). The metallic inlay slightly over-rides the ceramic inlay's rim and thus protects it from blows / impingements. The ceramic cup and the metallic sleeve are preassembled in the factory. The surgeons obtains them as one component.
The third layer is the metallic back-up cup that lies outermost. At operation the surgeon attaches the free metallic back-up in the prepared hip socket first and then carefully puts the preassembled ceramic cup (inside its protective slide) into the metallic back-up. It is fixed there with a Morse taper.
The lower picture shows the Hedrocel TM (Implex/Zimmer) composite ceramic cup. The ceramic inlayer is enshrouded into a protective layer of polyethylene. The polyethylene layer overrides the ceramic cup's rim and thus protects it against impingements. The assembled ceramic-polyethylene layers are placed in a back-up made of porous metal.
The constructions with interposed polyethylene layer are also called "sandwiched" cups. (Zimmer).
The cup models with interposed soft polyethylene layer were developed because some surgeons feared that the ceramic on ceramic coupling was too "rigid" ("armchair" science probably). The sandwiched polyethylene layer should reduce this "rigidity". Instead the polyethylene layer proved to be a weak link (Park 2007). See later under Complications - Fractures of sandwiched ceramic cups.
Femoral shaft component construction
On the femoral shaft component's side, a thin neck is advantageous, because it makes possible greater range of motion without the risk of impingement of the neck against the rim of the cup.
Click on the icon for a full size picture
Thin and thick neck- shaft components (Click on the icon for a full size picture)
To avoid impingement of the cup component's rim, the engineers designed a thin neck on the shaft component, as you see on the total hip model on the left side of the picture. The shaft component of this hip model has a thin, conically narrowing neck and a relatively large ceramic ball (Trident TM, Stryker). The ball's diameter is 3,4 times larger than the cross-section of the neck.
The total hip model on the right half of the picture shows a total hip model (Corail TM, DePuy) that has a relatively thick neck part which has a cylindrical form as well. The ball's diameter is "only" 2.3 times greater than the neck's cross-section.
The lower two pictures compare the range of movement (red) for these two total hip models.
Obviously, the range of movement for a total hip with a thick neck is smaller and the risk of impingement is higher for total hip models with thick neck.
At operation, the surgeon places first the metallic back-up cup into the prepared hole in the acetabulum (hip socket), blowing and pushing it in place (a method called press-fit fixation). (For more information on this technique please visit the chapter Cemented and cementless THP).
When the metallic back-up is sitting firmly in place, the surgeon places very tenderly the ceramic cup with its protective sleeve into it. This is a tricky part of operation because the rim of the ceramic may chip off during this part of surgery. The metallic or polyethylene sleeve around the ceramic cup proper should help to avoid damage to the rim of the delicate ceramic cup.
There are, however, also cup models where all three layers are put together by the manufacturer. Even this manufacturing trick cannot, however, exclude disassembly of the cup, the ceramic liner may still dislocate and fracture (Hedrocel TM cup, Poggie 2007)
The ceramic ball has a conical bore hole that accommodates to a conical trunnion (conus) protruding from the prosthetic shaft. The length of the hole in the ball regulates the length of the neck of the prosthesis; the longer the hole in the ball, the shorter will be the resulting neck of the femoral component. See also the chapter The mechanics of Morse taper.
The surgeon thus can regulate the length of the neck and the tension of the soft tissues around the new total hip directly during the operation.
4CERAMIC TOTAL HIPS: THE RESULTS
What is a failure?
Every time the surgeon is forced to operate again on the total hip and change one or both components of the total hip joint is a failure; the causes of the failure may be very different, infection, dislocation, and loosening are the most frequent ones.
The published results thus give the percentage of failures. In the following there are these failures given as annual failure rates. This annual failure rate shows how many percent of all ceramic total hips failed every year during the postoperative period.
The present results:
At present, four large scientific studies are being performed in the United States with totally more than 2000 operations with ceramic total hips enrolled. The studies enclose Transcend and Lineage total hip (both Wright Medical Technologies), ABC System, and Trident System (both Stryker Howmedica Osteonics). These studies are presented on the following diagram..
Annual failure rates for ceramic total hip systems (USA study)
The horizontal line in the diagram represents the benchmark for cemented metal on polyethylene total hip with annual failure rate of 0.5%.( the data from the Swedish National Hip Register, Malchau)
The picture shows that the annual rate of failures of ceramic total hips in this study varies from 0.6% (Transcend and ABC System), over 0.9% (Trident), to 1.4% (Lineage). (Data from Heisel 2003, Wright, and Stryker.).
One should note in the diagram, however, that the cemented polyethylene-on-metal total hips in the Swedish National Hip Register have had the annual failure rate of only 0.5%, which is lower than all compared ceramic total hip systems!
It is true that the USA study has had its own control group – patients operated on with an ABC polyethylene-on-metal total hip. In this control group there were totally 4.2% revisions, unclear over how long time, probably over 2 years. This is so exceedingly high failure rate (2.1% annual failure rate probably), not observed with other cementless total hip systems, that one may ask if it was ethical at all to use such bad total hip model for operations of the patients in the control group. In every case, this "control" group cannot serve its purpose.
The results of sandwiched ceramic cups
Published reports of sandwiched ceramic cup show rather high failure rates of some of these systems. See more in Complications / Fractures Sandwiched systems.
Some authors maintain that the cause of these failures is the combination of the "soft" polyethylene with the hard "ceramic". The soft polyethylene eventually disintegrates and the ceramic cup loses its support. The alumina ceramic is then exposed to excessive pressures and fails. It is the wrong construction, not the wrong ceramic that is the culprit.
Complications of ceramic TH
There are some failures that are specific for ceramic total hips;
6A Impingement
In extreme hip joint positions, such as during too much bending, the neck of the femoral component may strike, impinge, against the rim of the cup component. This is called impingement of the total hip joint.
See the mechanism of impingement: On the upper picture the patients makes the knee-to-chest exercise, she bends forcefully the thigh against the chest. In her ceramic total hip the neck of femoral stem impinges against the rim of the ceramic cup.
On the lower picture you see this situation in more detail (schematically):
The metallic collum (neck) of the femoral stem strikes (impinges) against the rim of the ceramic cup (yellow). Ceramic cup of this total hip model has a metallic back up (blue) that is, however, level with the edge of the ceramic cup. Therefore, the metallic back-up does not protect the ceramic cup against the strike from the collum (neck) of the stem component.
Impingement of the ceramic total hip.
Click on the icon for a full size picture
With every such extreme movement the edge of the ceramic cup receives a blow. The chipped off ceramic cup is a weak ceramic cup. Eventually, continuing blows / impingements fracture the cup which splinters into many fragments.
Do never such extreme movements and exercises!
The risk of impingement increases with faulty position of the cup, with the extreme movement in the hip, with some constructions of total hips (with the "thickness" of the neck).
There are thus some ways how to diminish the risk of impingement:
One is more precise placement of the cup during the surgery. Recent report demonstrates that use of computer navigated insertion of components reduces the risk of faulty position of the cup and diminishes the risk of impingement (Sugano 2007).
The second is patient's awareness of risks of extreme movements in the ceramic total hips. There are computer programs that construct the range of movements from x-ray pictures. These programs then demonstrate which hip movements produce danger of impingement. After such analysis the surgeon may may warn and instruct the patient which hip movements to avoid. (Toni 2006).
Fracture of ceramic components.
This is the complication that still scares both patients and surgeons from the use of ceramic total hips. For history of this complication see the chapter History of Ceramic total joints.
Fractures of modern ceramic balls are very rare. That is so because the modern medical grade ceramic has very fine structure , is produced by a special HIP procedure (see the chapter Ceramic material), and is individually tested before use with weights 60 times greater than the patient body weight (60 times 77 kg). This process produces very reliable ceramic ball components. The reported fracture rate of modern ceramic balls is exceedingly small: 0.004% or 4 in 100 000. (Heisel 2003).
Even in modern times the fracture of the ceramic ball is a serious complication. For details why read the chapter Ceramic Ball Fracture.
Picture of fractured ceramic ball (From Greenwald 2001)
Ceramic Liner fractures
in sandwiched total hip systems occur relatively often. The three last reports demonstrated 1.1% (4/357) (Park 2006); 5.7% (2/35) (Hasegava 2006); and (4.4%) (Poggie 2007) of such fractures, respectively.
The fracture often starts as a failure of the binding between polyethylene sleeve and ceramic liner which is caused by impingement of the neck against the rim of the liner.
Picture of fractured ceramic liner inside its polyethylene protective sleeve. (From Park 2006)
Early diagnosis of ceramic cup /ceramic liner fracture
Ceramic liner fractures may present from the beginning as hair-fine fracture lines. These fractures are often caused by repeated small traumas (impingement) and the right diagnosis is often made too late. In rare cases, one can see small fragments of ceramic on x-ray picture. Another sign are noises from the hip during walking. Only when the whole liner eventually splinters (upper picture) the patient perceives pain.
If the surgeon has suspicion of ceramic liner fracture he /she may take the joint fluid from the ceramic hip for analysis of small ceramic particles. If the joint fluid contains greater quantity of ceramic particles revision operation should be considered (Toni 2006).
Loosening of ceramic components
has been reported for 0.5% of components in the Lineage System.
Postoperative infection of ceramic hips
has been reported for 0.7% of operations with ceramic total hips in the USA study. This rate is like the rates of postoperative infection observed in operations with other total hip systems.
Dislocation of ceramic hips
Has been reported for 2.4% of ABC systems and for 1% of the Transcend and Lineage systems. The rates of dislocations for other total hip systems varies from 0 up to 7%, so that the dislocation rates of ceramic hips are not specially low, but not exceptionally high either.
Possible concerns with ceramic total hips
Noises from ceramic total hips
Many patients feel clicking or squeaking noises in their new total hips. Usually, these sounds are not followed by pain. These sounds usually occur when the patient changes the position in the hip joint. They may irritate the patient. According to some investigators the squeaking noises occur more often in patients with ceramic total hips. (see Stryker website)
The surgeons have two explanations for this sound phenomenon:
First, The clicking noises may be caused by a tendon or scar tissue streak that glides over the protruding portion of the new total hip joint. When you can put your hand (or the surgeon can do it) over the jerking tendon or scar tissue the diagnosis is clear, otherwise it is only a conjecture. When these clickings cause no pain or other problems you should not br bothered.
Second, the clicking noises may be caused by very small "pistoning" movements of the ball components in the polyethylene cup. The patients sometimes also feel small jerks in the total hip with change of the position.
X-ray studies of patients with total hip joints demonstrated that the ball component separates from the center of the cup component during gait.
When the operated on leg swings out during the gait cycle (the hip is not loaded) the ball component moves out of the centre of the cup and comes in contact with the rim of the cup. The ball separates from the cup.
When the leg then comes back in contact with the floor (the leg takes the body's weight) the ball returns to the close contact with the whole cup. The body weight presses the ball in the centre of the cup.
Thus, during the gait cycle the ball component moves from the center of the cup to the outside of the cup and then backs to the centre again like a piston. The "pistoning" movements are small, between 0.8 to 5 millimeters. Studies showed that these "pistoning" movements occur in total hips where the metallic ball articulates with polyethylene cup (Dennis 2001) and in total hips with ceramic bearing surfaces. The "pistoning" movements were not observed in metal on metal total hips (Komistek 2002).
Left side: During stance phase when the operated leg is in contact with the floor, the ball component is in close contact with the inside of the cup component. The body weight pushed the ball into the centre of the ball. Right side: during the swing phase of the gait, when the leg is swinging in the air, the total hip is not loaded with the body weight. The ball component moves out of the centre of the cup and comes in contact with the peripheral rim side of the polyethylene cup component. The tonus (springiness) of the muscles around the hip pushes the ball upward. The ball is in contact with only the rim of the cup.
When the patient then tramps with full weight on the limb, the ball glides forcibly back to the centre of the cup. Thus, the ball makes piston-like movements out of and back into the centre of the cup during gait.
The pressure during this movements is concentrated to a small area of the cup and the wear in this area increases. The surgeons speak about "stripe wear". The patients may feel "pistoning" movements and hear clicking sounds.
Picture: "Pistoning" (piston-like) movements of the ball component
Click on the icon for a full size picture
The clicking, pistoning movements may be more pronounced during rising from the chair or negotiating stairs.
It is important to realize that these piston-like movements are very small, only about some millimeters, although the patients feels / hears them very distinctly.
Simulation of the "pistoning" motion of the ball inside the cup in laboratory produced loud squeaking noises. (Stewart 2003)
What is the practical importance of this small pistoning movement?
Studies demonstrated that these noises from ceramic total hips are associated with faulty position of the ceramic cup (Walter 2007)
Stripe wear
Stripe wear is the term used to describe the long, narrow area of wear damage seen on some femoral balls retrieved from alumina ceramic-on-ceramic hip-bearing couples. This unusual shape of the damage is the result of line contact between the head and the edge of the liner. Stripe wear has been reported in first- and second-generation alumina bearings and has been associated with steep cup component position in young patients. Again, the problem lies in the faulty position of the cup, not in the ceramic itself.
It was hoped that with improved material properties of the ceramic and better operation technique the edge loading wear of the ceramic could be prevented. However, recent reports of stripe wear in the third-generation alumina ceramic-on-ceramic bearings with well fixed and well positioned acetabular components suggest that another phenomenon is occurring, and this led to a second theory for the cause of the stripe wear.
Researchers have proposed that micro-separation of the bearing centers occurs during the swing phase of normal walking and that the subsequent edge loading with heel strike causes the stripe]. Studies on patients using video fluoroscopy have shown that pistoning (or microseparation) of hip bearings can occur during walking gait and cause stripe wear. See also the chapter Life with a TH / sounds
The real importance of this special form of wear that may occur in up to 50% of all ceramic components is unknown at present (Walter 2004).
Bad results of revision operations of failed fractured ceramic total hips
Although rare, the revision operation for a fractured ceramic component carries a high risk of failure. The splintered fragments of the ceramic device are hard and sharp. If left in the wound these fragments would act as a grinding paste and would quickly grind down and destroy the new total hip. Revision operation for a fractured ceramic component is thus difficult, because the surgeon must remove carefully not only all visible splinters of the fractured ceramic component but also all soft tissues together with the rest of the total joint component. This is a major surgery and the failure rate of these operations has been up to 31% (Allain 2003).
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References:
Dennis DA et al. J Biomech 2001; 34: 623-29
Komistek L et al.: J Bone Joint Surg Am 2002; 84-A: 1836 -41
Lombardi AV et al. J Arthroplasty 2000; 15: 702- 9
Stewart TD et al. J Arthroplasty 2003; 18: 726 – 34
Stryker: www.stryker.com/orthopaedics/sites/trident/healthcare/ceramictech.php
Walter WL et al.: J Arthroplasty 2004, 19: 402-13
Walter WL, et al.: Squeaking in Ceramic-on-Ceramic Hips The Importance of Acetabular Component Orientation. J Arthroplasty. 2007 Jun;22:496-503 Revised August 2007
7CERAMIC BALL COMBINED WITH POLYETHYLENE CUP
In this total hip system the ceramic ball component articulates against the conventional polyethylene cup component.
Ceramic balls produce 2 - 3 times less wear particles when articulating against polyethylene cup than a metallic ball. (See Diagram)
Three sorts of ceramic are used for manufacture of these ceramic balls
alumina ceramic,
zirconia ceramic,
oxidized zirconium metal (Oxinium TM).
Total hip systems with balls made out of alumina:
Have been in use since 1970’s. The long-term results, published recently, with such old ceramic total hips operated on with old cementing techniques still demonstrate the annual failure rates of 1% only (Urban 2001).
The modern polyethylene on ceramic systems show one of the lowest annual failure rates. A multi-centre study conducted by Austrian surgeons on 800 patients operated on with the Alloclassic cementless total hip system and followed for seven years demonstrated an annual failure rate of only 0.21%!
See also the chapter Ceramic for total joints
Total hip systems with balls made out of zirconia ceramic.
Zirconia is a high-strength ceramics suitable for medical use, two to three times stronger than alumina. It also produces less wear particles when it articulates against polyethylene in a total hip system (in laboratory tests). See the Zirconia ball picture
Zirconia ceramic balls were introduced into use in 1985 in Europe and approved by the FDA in the USA in 1989.
Unfortunately, the crystal formation of zirconia ceramic is unstable and must be stabilized with another ceramic –yttrium oxide. See the chapter Ceramic for total joints
The published results of total hip systems with zirconia balls are an enigma.
Despite the fact that zirconia ceramic balls were in use eighteen years and more than 400 000 were sold by only one of the many manufacturers, there exist only two clinical studies showing good results with total hip systems with zirconia balls; the rest of the reports shows bad results with zirconia ceramic in these hip systems (Clarke 2003).
The statement from Smith & Nephew is revealing:
"Although ceramic total hip systems may extend the life of hip implants by reducing the wear, a major recall of ceramic ball components by the French manufacturer Saint-Gobain Desmarquest in 2001 reinforced surgeon concerns that some ceramic implants may be prone to fracture inside patients. As a result, only ten-percent of (total hip) procedures now involve the use of ceramic implants."
Oxinium - Total hip systems with balls made out of oxidized zirconium metal.
Zirconium metal is biocompatible and strong enough to be used for manufacture of ball components. One manufacturer exploited this fact for production of a ball component made from Zirconia metal (actually an alloy of Zirconia and Yttrium).
In a special process the surface of the ball is then oxidized. This process creates a thin layer of zirconia ceramic on the surface of the Zirconia ball. See more in the chapter Ceramics for total hips).
This product thus should have the smoothness and low wear characteristics of zirconia ceramic, whereas the ball itself would not be not brittle because it is made from metal. Thus, this ball will not be at risk for a fracture. The Smith & Nephew Company introduced recently the oxidized zirconium ball on the market under the name of Oxinium total hip system (http://www.strongasanox.com). Note that the oxidized Zirconium femoral ball is black and articulates with polyethylene cup.
Note also that the cup component is placed in a metallic sleeve. This sleeve is made from cobalt chrome. Cobalt chrome alloy is twice as hard as the "soft" zirconium alloy from which is made the ball component.Under normal circumstances these two metals do not come in contact and thus the hardness discrepancy is not a problem.
If the hip would dislocate, the soft Oxinium head would come in contact with twice as hard metallic back up of the cup This would lead to problems. See under Complications.
Oxinium total hip Click on the icon for a full size picture
At a hip dislocation, the Oxinium cup comes into contact with the metallic rim of the sleeve of the cup: The harder metal of the sleeve produces deep scratches on the surface of the softer ball. The cup component made from the soft polyethylene then articulates with the rasping surface of the damaged Oxinium ball. The scratches on the hard ball surface are effective in destructing the very soft (in comparison) polyethylene cup.
Dislocated Oxinium TM ball
A - x-ray picture of the dislocated Oxinium ball that is in contact with the metallic sleeve on the outside of the cup. The contours of the Oxinium ball and the metallic back -up are artificially blue.
Only the metallic sleeve is x-ray opaque and is depicted, the soft polyethylene cup is not seen.
B - the deep scratches on the surface of the dislocated Oxinium ball. This ball is depicted on the upper x-ray picture.
The ball was removed at subsequent surgery.
( Both pictures from Evangelista 2007)
C- the Oxinium cup with intact surface layer of black zirconium oxide for comparison. (Smith&Nephew)
Damage of the dislocated OxiniumTM ball. Click on the icon for a full size picture
Thus, for patients with dislocated Oxinium total hip the surgeon must open the total hip, remove and replace the scratched ball with all risks and problems that follow such a revision operation. (Evangelista 2007)
Dislocation of a total hip is in the majority of patients with other total hip systems usually managed by reposition on the emergency room without need of an operation. For patients with Oxinium TM total hip the dislocation becomes a serious problem needing an extended surgery with all possible risks. Because of this risk some surgeons now say that they will not use the Oxinium total hip until this problem is solved.
Hardening of the total joint surfaces by diffusion of gases is nothing new in the history of total joints. Nitrogen diffusion was once used for hardening of titanium made ball components; the laboratory results were splendid, the clinical results were a fiasco.
Reference: Evangelista GT et al.: Surface damage to an Oxinium femoral head... J Bone Joint Surg-Br 2007; 89-B: 535 - 7.
Ceramic ball articulating with metallic cup
Such total hip joints are under clinical testing by a team from DePuy manufacturer and the University of Leeds, England, headed by professor John Fischer from Leeds.
Questions to ask your surgeonWhat operation are you recommending?
Please explain to me the surgical procedure. I wish to know which surgical approach you will use. How will the surgical approach influence my postoperative rehabilitation and recovery? What are the risks associated with the proposed surgical approach (nerve damage e.g.)
Why do I need the total hip surgery with just the ceramic total hip system?
(because of my age, my activity level, disease of my hip joint?)
Are there alternatives to total hip surgery?
What are the benefits of having total hip surgery done with ceramic total hips?
What are the risks to have a ceramic total hip?
What ceramic total hip do you use? How reliable are the components? Is there any risk of mechanical damage of the ceramic components?
What are the risks for possible complications such as dislocation, infection and loosening with this type of total hip?
What if I don’t have this operation?
What I will gain or loose by postponing the total hip surgery now? Could the surgery be more difficult if I wait?
Where can I get a second opinion?
Getting a second opinion from another doctor is the best way to make sure that the total hip surgery is the best option for you
What has been your experience in doing this operation?
One way to reduce the possible risk of total hip surgery is to choose a surgeon who has been thoroughly trained to do the total joint surgery and has plenty of experience doing it. It may be perhaps more comfortable to discuss the topic of surgeon’s qualification with your primary doctor
What kind of anesthesia will I need?
Ask to meet the doctor who will give you the anesthesia. Ask what the side effects and risks of having anesthesia are in your case.
How long will it take me to recover?
When can I return to my previous activity, sports? When can I return to my previous work? Will there be any permanent restrictions on my activity?
References:
Poggie et al : J Bone Joint Surg-Am 2007;89-A: 367 -75
Clarke I C et al.: J Bone Joint Surg-Am, 2003; 85-A-Suppl 4: 73- 84
Greenwald AS et al: J Bone Joint Surg-Am, 2001; 83-A-Suppl 2/2: 68- 72
Hamadouche M et al: J Bone Joint Surg-Am, 2002, 84-A, 69-77
Hasegawa Y et al.: J Arthroplasty 2003, 18: 245
Hasegawa Y et al: J Bone Joint Surg-Br 2006; 88-B: 877 - 82
Heisel Ch et al.: J Bone Joint Surg-Am, 2003, 85-A, 1366-79
Warashina H, et al.: Biomaterials. 2003; 24(21): 3655-61
Malachau H, et al.: www.jru.orthop.gu.se
Allain J et al. : J Bone Joint Surg-Br. 2003-A; 85-A, 825 - 30
Walter J et al.: J Arthroplasty 2004; 19:
Wright Medical Technology - www.wmt.com
Stryker Howmedica Osteonics – www.stryker.com
Toni A et al: J Bone Joint Surg-Am, 2006 88-A; Suppl 4 : 55- 63
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Revised April
2006