Joint replacement is a common surgical procedure with a high success rate. In an arthritic hip, the damaged ball (the upper end of the femur) is replaced by a metal or ceramic ball attached to a metal stem fitted into the femur
(with or without cement), and a plastic or ceramic socket (fitted into a metal socket) that is implanted into the pelvis, replacing the damaged socket. Using a combination of metal and plastic, the joint implant surgeon creates a new ball and socket joint which will glide smoothly and painlessly. During the past two decades, multiple advances in hip arthroplasty have been accomplished and many types of prostheses are available and currently used. The metals
used are chrome cobalt alloy and/or titanium alloy. These are super metals initially developed for the aerospace industry and now adapted for the orthopedic industry. The plastic is a high-density plastic polymer called polyethylene. In younger patients a ceramic ball is used with a polyethylene or ceramic socket.
Which type of hip prosthesis? The joint implant surgeon decides
for each patient individually which type of prosthesis he will implant. The decision depends on several factors, among them: - age
- bone quality
- shape or deformation of the bone (upper part of femur)
- deformation of the bone of the pelvis
Based on those factors and radiographs, the most suited prosthesis can be selected. At present there is a wide range of prostheses with different new types of articulations such as metal-on metal and ceramic-on-ceramic in stead of metal-on-polyethylene, based on new scientific research
and availability of improved metal alloys which may reduce the wear up to 1/4000. The use of exchangeable neck/ball (modular prosthesis) in primary as well as revision surgery has enhanced the surgeons amatory to create a stable prosthesis in most conditions and facilitates future revision surgery.
Types of hip prostheses Types used at our department are marked as  :     - ALLOFIT – METABLOC - METASUL
- BIRMINGHAM HIP RESURFACING (BHR) PROSTHESIS (see pdf-file)
  BESIDE THE ALTERNATIVE BEARINGS, metal-on-metal and ceramic-on-ceramic, to prevent the problems with polyethylene-wear new polyethylenes are produced. They are called HIGHLY CROSSLINKED POLY’S. These should be stronger and more wear
-resistant. Older cross-linked poly’s functioned well (OONISHI-GROBBELAAR) in history but are not the same as the present ones. If they will stand longer then the old or conventional plastic, and if the good laboratory results can be accomplished in the body, only time can tell. (ABSTRACT J. Fisher , Hip International) -
“Custom made” PROSTHESIS: in rare occasions of extreme deformation of the joint or femur, the surgeon may need to use an individually designed prosthesis based on radiographs and CT-scan of the patients’ hip.
 
FIXATION OF THE PROSTHESIS There are currently several methods used for attaching the prosthesis to the bone and providing stable fixation to prevent movement between prosthesis and bone. - BONE CEMENT (=polymethylmetacrylate or PMMA) provides mechanical attachment of the prosthesis to the bone. Cement does not act as glue as there is no fixation of cement to a smooth surface.
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PRESS FIT : depends on a very tight fit of the device into the bone. This is achieved by placing a somewhat bigger device into a somewhat smaller shaft or socket under pressure.
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BIOLOGICAL INGROWTH : uses a metal prosthesis fabricated with a special surface (ex. porous coating, rough surface), which enhances bone growth into and onto the surface. Extra surface coatings, such as hydroxyapatite, are also being used to hasten and/or enhance bone fixation.
 Remark : hybrid fixation is when one component is inserted without cement, usually the socket, and one component is inserted with cement, usually the stem.
SURGERY You will be admitted on the day prior to surgery to allow necessary preoperative examinations such as blood sampling, X-ray
of the chest and ECG. You will be visited by the specialist anesthetist and if necessary by a specialist heart and lung physician. In most cases general anesthesia is used. We prefer general anesthesia because of the posterolateral approach with patient positioned on his side and to obtain an optimal muscle relaxation, especially in case of a resurfacing procedure in young
patients with strong muscles. Low bloodpressure is easier obtained to reduce the blood loss in surgery. Before the operation the surgeon determines the size of the prosthesis with templates on the X-rays of the hip.  
For surgical technique total hip replacement, see demo video sawbones and other videos on resurfacing.
For the normal hip anatomy of resurfacing prosthesis, see demo video sawbones.
After the operation, patient will be transferred to the recovery room for observation for a couple of hours. A check X-ray of the new hip will be taken and shown to the surgeon before patient returns to the hospital ward. There will be a drain in the hip wound draining blood from the operation site. Onset of rehabilitation depends on the type of prosthesis or surgery: the next
day in case of a resurfacing procedure, and in case of a classical total hip replacement after 2-5 days in case of revision surgery.
Discharge out of the hospital depends on type of prosthesis, surgery and physical condition of the patient : - resurfacing procedure : after 3-4 days
- a classical total hip prosthesis in the young active patient : after 5-7 days
- a classical total hip prosthesis in the elderly : after 7–14 days
- for revision surgery depending on extensiveness of the surgery and age of patient : after 7–21 days
Complications
As with any type of surgical procedure, there are certain risks or complications associated with total hip replacement. We aim continually to provide the optimum environment for your surgery and recovery, minimizing any potential complications. You always are free to ask for more information if required. In case of revision surgery, specific complications related to the individual surgery will be discussed with the patient before
surgery. Our primary goal is to assist you through your total joint replacement procedure with minimal complications and maximum recovery. Therefore, we will be instructing you in guidelines that will aid in the healing process. The most encountered complications are : - Deep Vein Thrombosis (DVT) and Pulmonary Embolus (PE)
Post-operative DVT is one of the most common complications following hip and knee surgery, and is caused by immobilization in combination with damage of the veins because of the manipulation during operation. Pulmonary embolism (blood clot traveling to the lung) can be fatal and can occur suddenly. Several measures are used to prevent the formation of blood clots in the legs : TED stockings day and night during hospital stay, bed exercises and blood
thinning drugs (Low Molecular Weight Heparin) subcutaneous once a day during 3 weeks (see Guidelines for Returning Home). See further exercise section below. - Dislocation
Dislocation occurs when the ball of the hip joint pops out of the socket. It is uncommon and usually preventable after
hip replacement surgery. Prevention depends largely on patient education and care in the postoperative period (see Guidelines for Returning Home).
Hip dislocation can occur at any time after surgery. However, it is most likely to occur within the first six weeks post-operatively. The muscles and soft tissue (capsula) around the hip socket are healing during this time. They are not
strong enough to hold the ball in the socket when the hip joint is under certain kinds of stress. Movements and positions that produce these stresses should be avoided in the post-operative period. Hip dislocation is usually accompanied by a pop or noise, and by pain in the groin and/or buttocks. The affected leg will feel and look either much shorter or occasionally much longer. The foot may be rotated either outward or inward. Patients are mostly
unable to bear weight or walk on the affected hip. A hip dislocation is not life threatening but should be treated promptly. Dislocation is confirmed by X-ray. If the hip is dislocated, it is usually reduced (put back in position) under general anesthetic. This procedure is called a closed reduction; a surgical incision is not required. Very rarely, the hip cannot be relocated by closed reduction and an open reduction (through an incision) is required. Dislocation rate of 1%
is reported as usual following total hip replacement, reaching 10%-15% after revision surgery. When performing a resurfacing procedure, the chance for dislocation is extremely low. In our series of 1900 procedures so far, we have seen only 6 dislocations! The reason for that is the use of much larger diameters (36-58 mm) of the head, in stead of the small heads (22-32) more often used in classical THA (see article). This creates a larger intrinsic stability. For that
reason we started using the same principle in revision surgery, using larger diameters of the head in the articulation with metal-on-metal, using a dysplasia cup or a resurfacing cup component. The large modular metal head suits perfectly on the stem in the femur (Eurocone). In this way we hope to reduce the chance for dislocation after revision surgery to an absolute minimum (4% in stead of 14%).
  - Nerve injury
Any incision can result in damage to the sensory nerves in the area of the incision. Significant nerve damage, which may
cause loss of muscle function, can occur after hip replacement. This type of injury is rare and is most common when the leg is lengthened more than one inch (such as in surgery for congenital hip deformity or revision total hip replacement). Nerve injuries of this type can lead to a ‘foot drop’ or the inability to raise the ankle or toe, in case of damage to the Ischial Nerve.
In case of palsy of the Femoral Nerve, there will be inability to keep the leg extended during gait. Most palsies recover spontaneously.
In case of an sciatic nerve problem, recovery is less common. It can take 2 years to be able to see any recovery.
In case of drop foot electrostimulation is done in the beginning. Bracing and special tools can help. The recovery of a sciatic nerve palsy is less obvious then a femoral nerve palsy. - Fracture of the shaft (femur)
When inserting the femoral stem (prosthesis), it might happen that the shaft of the femur fractures due to severe osteoporosis or bone loss in case of revision surgery due to osteolysis. Several types of adapted prostheses and materials are available to cope with this problem.
  - Infection
Overall incidence of infection is approximate 1%. Infection may occur early, within 6 weeks or late, even years after surgery. Early infection is treated with antibiotics and possible re-operation to clean out the hip and try to save the prosthesis from removal. Late infection generally requires re-operation with removal of the prosthesis and possibly a second stage operation to re-implant a new hip when it is safe (after 6 weeks of intravenous antibiotics). A 2-stage
revision can be done with use of an antibiotic impregnated spacer. In my institution a 1-stage procedure is performed unless this is not possible anymore for some reason. See also Revision Surgery. - Blood loss and transfusion
Joint replacement surgery involves significant blood loss usually requiring blood transfusion. Banked ‘homologous’
blood from Red Cross donors is stringently screened and tested to ensure that it is safe and free from infectious agents such as HIV and Hepatitis. Nevertheless, there is no guarantee that blood from ‘homologous’ donors is safe, or will not cause a blood reaction. The risk is extremely low.
In primary hip procedures and resurfacing the risk of bloodtransfusion is becoming low (see results page). In bilateral
hipprosthesis a bloodtransfusion is more often used (see results page). In these cases a cellsaver is used. - Leg length discrepancy
Most total hip replacements are unconstrained. This means that the ball is not locked into the socket, and the hip can theoretically dislocate with extreme movement. Stability is produced, in part , by soft tissue tension in the muscles and
ligaments around the hip. Sometimes it is necessary to lengthen the leg, which tightens the soft tissues, to improve the stability of the hip. Leg length difference is usually less than 5 mm in the vast majority of cases, but can be up to 2.5 cm in unusual circumstances, requiring a shoe raise the other side. Some patients feel longer after hip replacement without true lengthening. This is called “functional leg length discrepancy” and is due to tightening of the muscles
around the new hip. This feeling of lengthening of the leg can take 6 weeks to 3 months to improve and requires stretching exercises of the hip and pelvis.
In our service leg lengthening is in all cases NOT RECOMMENDED. - Heterotopic ossification - HO
This is an abnormal calcification/ossification of the muscles around the hip joint, creating a stiff hip joint! Prevention consists of daily admission of indomethacin (or another NSAID), a strong anti-inflammatory drug, during 3 weeks after surgery. In case of contraindications for admission of the drug (e.g. Stomach ulcer) or when patient is severe at risk for HO (e.g. spondylitis ankylosans – Bechterew disease), a single dose of radiation (700 rad) is given the day before or after
the operation to prevent HO. When the hip becomes completely stiff, surgical resection of the ossification is mandatory (see also publication: Early Resection of Heterotopic Ossification after THA).
  For
prevention of thromboses, the following exercises must be continued: - Cough and deep breath
Take the parrot of the bed with both hands. Take a deep breath in and out. Cleanup not only the throat, but cough deeply enough to get out the thicker mucous layers out of the lungs. - Calf pump
When laying in bed, or sitting in a chair,
exercise as much as possible with your calf muscles. Also continous movement of ankles and feet are encouraged. - Thigh muscle exercises
Exercises of the quadriceps muscle develop an important tone in your legs. Stretch your leg on the bed, and push down your knee on the bed. Tighten your muscle and make it as hard as possible. You may put a rolled up towel in the hollow of your knee first. - Chair level
The sitting height of the chair may not be to low. Do not use a relax chair. Your hip joint may not be in a lower position than your knee joint. - Position of the bed
Do not put the head-end of the bed straight-up for a too long period. Rest in bed in a flat position, such that your hips are in a straight, neutral and relaxed position.
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Last updated: 06.01.2006 | 
