HIP DISEASES

Arthritis

Osteoarthritis

Rheumatoid arthritis

Lupus

Femoral head necrosis

Hip dysplasia

Hip dislocation congenital

Impingement of the hip joint / Torn Labrum

Slipped epiphysis

Previous hip infection

Fused hip joint

Ankylosing spondylitis

Main hip diseases - Incidence

The three main hip joint diseases that eventually lead to total hip replacement are:

• Primary osteoarthritis ( 76 %)
• Rheumatoid  arthritis (6 %)
• Conditions after hip fracture (11 %)

The spectrum of hip diseases for total hip operation varies with the age of the patients.

In young patients prevails rheumatoid arthritis together with secondary osteoarthritis after childhood hip diseases.

In older patients the prevailing disease for total hip joint replacement operation is idiopathic osteoarthritis.

ARTHRITIS

The term arthritis literally means inflammation of the joint ( arthritis= Greek for joint inflammation), but the English language uses this term to describe any condition in which there is a damage to the joint, even cases where any inflammation is not present .

It is  important to distinguish between

• osteoarthritis which  is a strictly local condition that usually affects only one or two major joints, and it is no inflammation in spite of  the ending "-itis".
• Rheumatoid arthritis which is a serious systemic disease, affecting not only several joints but also other organs as well. This is an inflammation, as the ending " -itis" rightly announces.

Usually the pain in an arthritic joint early on is due to inflammation of the synovial lining. In osteoarthritc joints and in avascular necrosis,   the pain is also related to the increased blood pressure inside the bone marrow. In the later stages, when the cartilage is worn away, the pain and stiffness come also from the friction of raw bones grinding on each other.

OSTEOARTHRITIS   OF  THE  HIP  JOINT  (OA)

Surgeons distinguish two forms of osteoarthritis:

• the idiopathic OA - as the name idiopathic says  no one knows for sure what causes the destruction of joint cartilage
• whereas in the secondary OA   one knows the cause of the joint cartilage destruction.

The changes of the hip joint in both forms are identical.

The frequency of idiopathic OA increases with age, but it is not simply an aging process.

The secondary OA develops after previous damage to the hip joint. The joint damage produces uneven loading of the joint surfaces with peak loads localized to small areas of the joint surface. The peak loads successively destroy the joint cartilage.

The secondary OA may be caused by an

inborn hip condition such as a congenital hip dysplasia

to be  a result of previous fracture through the hip joint, pelvic or thigh bones, or

be caused by previous inflammatory process in the hip joint such as infection.

In an osteoarthritic hip joint the quantity of bone mass close to the joint surface increases, this is called sclerosis because the bone substance is harder.

The contours of the bone ends enlarge and bony spurs form at the periphery of the hip joint. Small fragments of joint cartilage float in the joint space and cause secondary inflammation of the synovium (the lining of the joint space) with swelling of the joint.

There is no blood test for osteoarthritis. Laboratory tests are only necessary if your doctor feels other types of arthritis (such as some forms of rheumatoid arthritis) need to be excluded from the diagnosis.

The X-ray picture of an osteoarthritic joint is characteristic: The black shadow of the joint line is lost. The quantity of bone mass is increased, presenting a sclerotic zone close to the joint surface with bone spurs. The joint surfaces are deformed.

Subchondral bone cysts

Click on the icon for a full size schematic  picture.

In dysplastic hip joints, the femoral head contacts the hip socket (acetabulum) on only a small area. The stresses on the bone lying under the joint cartilage (subchondral bone) are maximally exaggerated.

The subchondral bone in this area dies and is replaced by a cavify filled with loose connective tissue - a bone cysts is formed. On the X ray paicture the bone cyst is seen as a darker, well delineated area close to the joint line. These cysts may form "a mirror image".  Usually the cyst in the acetabulum is larger than the cyst in the femoral head.

If the cyst is large, in may be necessary to fill it with patient's own bone tissue during the total hip replacement operation.

Do all patient with osteoarthritis of the hip joint need an operation?

Large statistics demonstrated that between 40 to 60% of all patients with signs of osteoarthritis of the hip  on a X-ray picture are satisfied with conservative treatment.

Patients with only limited damage  to the joint cartilage, not too old (<55 years),  and with still retained ability to bend their hips up to 90 degrees, may be candidates for femoral osteotomy. Before the total hip arthroplasty became almost a routine, the procedure of choice for an osteoarthritic hip was an osteotomy. This operation relieves pain but it does not increase the range of motion in the hip,

There are known cases of patients who have had osteotomy on one hip and total hip on the other hip. Not seldom the total hip failed after some years whereas the osteotomy lasted more than twenty  years until the patient's dead. (Harris WH, J Bone Joint Surg-Am, 1995, 77-A, 603-7)

For more information on the osteotomy, visit the chapter Alternative hip operations

Patients with severe osteoarthritic damage to the hip joint, pain and stiffness,   are candidates for total hip prostheses.

Patients with idiopathic form of osteoarthritis are not seldom heavy individuals with large hip joints and much sclerotic bone. This may make the surgery more difficult. These patients have in general a well -preserved mobility in other joints. After the total hip replacement these heavy patients often put excessive loads on their new hip joints with risk for earlier loosening.

Young patients with osteoarthritis secondary to a hip fracture have increased failure rate of total hip replacements.

The patients with idiopathic osteoarthritis of the hip  are also more prone to develop deep vein thrombosis after total hip operation.

RHEUMATOID   ARTHRITIS  (R.A.)

Rheumatoid Arthritis (R.A.) Is a general inflammatory disease. It comes in waves (flares and remissions). If untreated, as years pass, the inflammation becomes a norm. In addition to painful, inflamed joints, many people with R.A. feel as if they constantly "have flu", feeling mild fever, extreme fatigue and weight loss.

The same inflammatory process that damages the joint can also affect the eyes, lungs, heart, kidneys, and blood vessels. Untreated severe R.A. has the potential to shorten the patient’s life.

The cause is not known. The joint inflammation successively destroys the joint cartilage and bone tissue. Bone tissue becomes soft, the damage to the bone tissue may be enhanced by the corticosteroids used for treatment of R.A.

X-ray changes

may be similar to the changes observed in osteoarthritis in that the shadow of joint line is lost. But the X-ray pictures of a R.A. joint also show a striking loss of bone tissue in the skeleton around the inflamed joint. Sometimes a large parts of the bony joint surfaces are destructed by the inflamed joint tissue (synovial lining).

Blood tests:

The Erythrocyte sedimentation rate  is elevated. This test is, however, not specific for R.A.

Rheumatoid factor (RF),

an antibody secreted by certain body’s cells, is found in the blood of up to 85 % people with R.A who have had R.A. for more than 18 months. The positivity of this test usually  heralds the begin of a more aggressive phase of the disease.  This test is sometimes positive in otherwise healthy people aged over 70.

The skeleton  of patients with R.A.  is "soft", the marrow cavity of femoral bone is large, and these patients often have cortisone treatment also after the total hip replacement. Cortisone inhibits the   formation of the new bone. These factors taken together make the use of cementless total hip prostheses in patients with R.A. problematic.

There is one specific form of R.A. of the hip joint, where the softened bottom of the hip socket protrudes into the pelvic space, a condition called protrusio.   The hips of these patients are extremely stiff. Operations of this condition may be difficult. There is a risk of a fracture of the thigh bone during the operation of these patients.  

The engagement of other joints makes the R.A. patients less mobile.

Even improvement of the function in one joint  only by a total joint operation improves the situation of these patients considerably.

Moreover, the artificial joints of these patients are not exposed to excessive loads, so that the results of the total hip operation in these patients are surprisingly  good. There is also lover risk of deep vein thrombosis in the patients with R.A.

Because R.A. is a systemic disease, alternative hip operations such as hip osteotomy are not feasible. Also a limited operation, consisting in removal of inflamed synovial tissue (synovectomy), done often on smaller joints, is not feasible on the hip joint.

There are, however, some increased risks for patients with R.A. who are operated on with total hip replacement.

• There is an increased risk of prosthetic infection. The disease itself and the use of Corticosteroids make these patients susceptible to general infection which then  engages the artificial hip joint.

• There is an increased risk of fracture because the skeleton is soft

• These often have  very thin skin so that they often develop  skin bruises. These bruises may be infected and be a portal for a bacterial infection

• There is engagement of other joints which are equally stiff and destructed as the  hip joints. Stiff, immobile  cervical spine, with soft, partly destructed vertebrae, may produce problems for anesthesia. It is important to take X-ray pictures of the cervical spine and consult the anesthesiologist before the contemplated operation.

See also www.arthritis.ca/can

LUPUS (SLE)

Lupus (whole name Systemic Lupus Erythematosus or SLE) belong to specific inflammatory diseases called also collagen diseases. These disease attack soft tissues containing collagen fibers. Lupus is a systemic disease, which often damages hands, but  it  may damage also  large joints, mainly knees.   Lupus is  treated with high cortisone doses and these patients often develop osteonecrosis of  both hip joints. In a  patient with known osteonecrosis of one hip it is thus mandatory to evaluate and examine the other hip too.

Because  lupus is a systemic disease that damages heart, lungs, kidneys, and blood vessels, these patients must have a thorough preoperative examination and a   consultation with a rheumatologist   before the hip surgery could be contemplated.

AVASCULAR   NECROSIS  OF  THE FEMORAL  HEAD (AVN)

Under this name are assembled several diseases that have one thing in common: a segment of the bone in the femoral head loses its blood supply and dies. The process is called necrosis.

There are several conditions that may cause this disease. In practice, two forms of avascular necrosis of the femoral head are important:

• Traumatic femoral head necrosis: The femoral head has a precarious vascular nourishment. Fracture of the femoral neck or dislocation of the femoral head may mechanically damage the blood vessels that nourish the femoral head   and the bone cells will die.  The dead tissue in the femoral head cannot withstand the body weight pressures and the femoral head colapses.

• Non-traumatic avascular necrosis (AVN)

affects young adults between the ages twenty and fifty, 50 % of them have both hips affected.

The cause of AVN in this last patient group is not entirely clear. People with a history of alcohol abuse or who have taken large doses of cortisone for at least six weeks, and people with decompression sickness, cortisone producing tumors, and blood disorders such as sickle-cell anemia, are prone to develop AVN.

This is, however, a controversial issue.

30% of all patients with avascular necrosis are people treated with cortison (larger doses). On the other hand, of all patients treated with cortisone, only 8 % will develop avascular necrosis.

Similarly, the relation between the intake of alcohol and avascular necrosis is not at all clear.

It seems that there is a hereditary factor that makes some people more prone to develop avascular necrosis.

The scientist believe that the disease starts with formation of small clots in the small vessels nourishing the bone tissue of the femoral head.

The blood circulation need not stop completely, the bone cells die already when the blood pressure /and oxygen pressure/ drops down under a certain level.

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Symptoms and diagnosis

Early AVN usually causes very mild symptoms (groin pain) or no symptoms at all. Later on, the patients develop constant and very intensive groin pain. Successively, patients with AVN develop symptoms as with hip osteoarthritis.

The surgeons divide the AVN usually in four stages according to the changes seen on the X-ray pictures.

In stage 1, there are no changes on plain X-ray pictures, the diagnosis appears from a MRI examination.

In stage 2, there are changes on plain X-ray pictures, such as increased density, but the head has still  retained its form. The X-ray picture changes appear several months after the begin of the disease.

In stage 3, the X-ray picture demonstrate that the   head has collapsed, but the cartilage of the  hip joint  is still well retained

In stage 4, which is a late stage, there develops a   secondary osteoarthritis of the hip joint.

A MRI (Magnetic Resonance Imaging) is a very sensitive diagnostic method that reveals the first signs of AVN, even before there are changes on X-rays.

Any young patient with unexplained severe groin pain and a normal X-ray of the hip joint should have a MRI image of the hip. This is especially important for patients with any risk factors for development of AVN.

Because AVN often engages both hips, examination of the status of the other hip is mandatory in every patient with AVN of one hip joint.

About 80% of untreated hips with AVN deteriorate relentlessly and require total hip replacement  operation within 2 to 3 years from diagnosis.

The outlook is better for patients with small area of bone necrosis and for patents where the treatment started early.

Treatment of  AVN

depends on the extent of the  damage to the femoral head.

Non- operative treatment

Patients who decline surgical treatment should at least be on crutches for a few months to protect the hip from undue stresses. Perhaps 20 % of all patients don’t progress to total destruction of the femoral head, although their hips may remain painful.

Operative  treatment

Core decompression:

When the femoral head still has retained its round form the surgeons perform core decompression. In this operation several small channels are drilled into the core of the dead bone. In theory, opening the channel into the core of dead bone will achieve two things: It will lower the blood pressure, which is the cause of the intensive pain; and it will open ways for the bone from the neighborhood to grow into area and replace the dead bone.

To enhance the chances of bone ingrowth, some surgeons experiment with a substance called BMP (Bone Morphogenetic Protein). This substance, when present in sufficient concentration in tissues, engenders production of new bone tissue. Theoretically,  a gelatin capsule containing BMP, which has been placed in the defect after the removed dead bone,  releases BMP in sufficient concentration that should entice production of new bone into the area of AVN.

The reported success rates vary between 30 and    60 %.

Vascularized fibular graft:

A more exhaustive procedure is a vascularized fibular graft transplantation. This operation exploits the idea, that a graft of living bone tissue with retained circulation may enhance the "creeping substitution" of the necrotic bone area.  In this operation, applicable on patients who have largely retained contours of the femoral head, the surgeon takes out a segment of patient’s fibula together with its artery and vein, and places it as a duvet in the femoral neck. 

The reported success rates vary between 60 and  80 %.

For more information about these operations visit please the chapter  Alternative  hip   operations

Osteotomy :

The   avascular necrosis usually develops in the area of the femoral head that is subjected to the stress of the body weight . In some cases the femoral head may be rotated or turned so that another still healthy portion of the femoral head can become a new weight-bearing area.

This   operation  demands a very precise technique, otherwise there is a risk of damaging the vessels that nourish the femoral head and neck.  Such damage will instead  deteriorate the circulation and trigger more necrosis.

The reported success rates are less than 50 %.

After this operation, several weeks of non-weight bearing regime are necessary.  For more information  visit please the chapter  Alternative  hip  operations

Femoral head resurfacing:

Initially, only the femoral head is involved, whereas the socket is still healthy. Some surgeons thus cover the whole femoral head with a metal hemisphere, which matches the size of the femoral head. This procedure is designed to "buy time"for the younger patients.

The philosophy behind this procedure is following: It is known that over a longer period the metal coverage of the femoral head will gradually wear out the healthy socket. The destruction of the socket’s cartilage with following pain will need the surface replacement to be converted to a total hip replacement. Most patients with AVN are under 50, and will live further 30 or more years. Thus, two procedures will likely be necessary. It is then important that the first procedure does not make the future second procedure more difficult and less likely to succeed. A surface replacement procedure is a much more conservative procedure than a regular total hip replacement. Total hip replacement following some 10-15 years after surface replacement is more likely to succeed than a second total hip replacement that follows after a previously failed total hip operation.

For more information  visit please the chapter  Alternative  hip  operations

Total hip replacement.

When AVN is advanced to the point that there is involvement of the hip socket as well, then the only effective operation for these young patients is total hip replacement operation. The total hip prosthesis today, however, will not last these 30+ years most of these patients will live. Again, these patients must be informed that a second, revision total hip replacement will probably be necessary in the future.

As such, however, the THR for AVN is very effective with success rates of up to  95% during ten years.

 

Double-cup (surface) replacement.

There is a small group of surgeons who use a more conservative approach than the   total hip operation "to buy time" in patients with involvement of both hip joint surfaces. These surgeons cover the femoral head surface and  the socket surface with double  concentric metallic cups.

  For more information  visit please the chapter   Alternative  hip  operations

Useful links:

www.rothmaninstitute.com

www.hipsandknees.com

http://aboutjoints.com

Read: Mont M et al: Current Concept Review: Non Traumatic Osteonecrosis of the Femoral Head. J Bone Joint Surg-Am 2006; 88A: 1117 - 32

CONGENITAL   HIP  DYSPLASIA (CDH)

The term Congenital Hip Dysplasia refers to changes in the form of the hip joint, which are present already at birth.

In normal hip the head of the thigh bone is well contained in the hip socket (acetabulum), the surfaces are congruous and concentric. 

In congenital hip dysplasia the femoral head and acetabulum do not fit together. The term dysplasia means that both parts of the hip joint, the ball and the acetabulum, have abnormal development.

There are different terms to describe the severity of this condition, such as dysplasia, subluxation, and complete dislocation of the hip joint. More precise is the four grade scale proposed by Dr Crowe, where  grade  I  is   the  least severe and  grade IV describes complete dislocation of the hip. 

In  patients with dysplastic hips (Crowe grades I -III), the femoral head is "partially" out of the hip socket; the socket is not congruent with the femoral head.  These patients have often had one or more hip operations during childhood which might caused considerable changes in the skeleton and scarring of the soft tissues. The majority of these patients are women.

Pain and stiffness caused by secondary osteoarthritis are indications for total hip replacement in these patients. The operation may be difficult because the changes in the skeleton.

The surgeon must enlarge the socket to accept a cup component. Sometimes the surgeon must use a bone graft  to create a new roof of the defective hip socket. Patient's femoral head or a piece of pelvic bone might be used for this purpose.

In some patients the operated leg has been  shorter and the muscles  considerably weaker before the total hip surgery. The recovery of full muscle force after total hip replacement is improbable.

The risks with total hip replacement of these hips include:

Remaining  insufficient strength in the muscles around the   replaced hip with resulting limp

Increased risk for hip dislocation in patients with insufficient muscle strength

Increased risk for sciatic nerve damage after difficult total hip  operation

Risk for uneven leg length

CONGENITAL HIP  DYSPLASIA  AND CONGENITAL  HIP DISLOCATION

Click on the icon for a full size picture

In normal hips, the head is well covered by the socket (upper picture)

  Note that the distance between the center of the hip and the attachement of abductor muscles is equal to the lever arm of these muscles.   Biomechanically this distance is called femoral offset. The longer this distance the less work need the muscle do to push the limb to the side.

In dysplastic, subluxated hips, (Crowe grade I - II),   (lower row, left picture)

  the socket of the hip joint is shallow and small. The roof of the socket is oblique and does not  offer any  resistance to the upward glide of the head. The head is deformed but is retained within the socket. The lever arm of the muscles is short (the femoral offset is short), so the muscle are forced to do more job to move the limb. With time the muscles  will fail by overexert and become weak.

In completely dislocated hips,  (Crowe grade IV) (lower row, right picture)

the femoral head is completely displaced out of the socket an comes to rest against the lateral wall of the pelvic bone. The socket is small or absent, the head is also small, the thigh bone is thin. The limb is short. The muscles are weak.

 CONGENITAL   HIP  DISLOCATION (CHD)

Congenital hip dislocation. These patient have seldom severe pain if the condition is bilateral. These patients have grave limp but in the absence of pain  there is no indication for total hip replacement.

The total hip operation of these patients is difficult, if ever possible. Because the hip skeleton of these patients is often extremely small the surgeon must use special small-size hip prostheses.  The restoration of a socket that will accepted a cup component may be very difficult. The placement of the femoral ball component in the new cup need the whole thigh bone to be drawn downwards several centimeters. The tension of soft tissues, including blood vessels and nerves, produced by this operation is considerable and may produce damage on nerves and vessels around the hip. 

Other risks with total hip replacement of totally dislocated hips are similar to the risks with the surgery of the dysplastic hips, only they are greater.

IMPINGEMENT OF THE HIP JOINT

(TORN LABRUM )

 What is labrum of the hip joint?

It is a fibrous structure that increases the depth of the hip socket. 

A - The upper image shows the skeletal socket of the hip joint (pink). It is a shallow bowl that would not catch the head of the hip joint properly. B - Thus, the skeletal socket is enhanced by a fibrous structure that is attached on the bony rim of the socket.  Note that the labrum increases considerably the deep of the hip joint cavity. Note also that the joint cartilage covers only a part of the sockets bottom, it makes a horseshoe -like blue pillow on this picture. C - This is a cross section (schematic) of the hip joint. You see the LABRUM as orange triangle-like structure, attached to the skeleton of the hip socket. From the labrum then continues the joint capsule that encircles the whole hip joint.

Healthy labrum that enhances the hip socket Click on the icon for a full size picture

The cartilaginous mass of labrum makes the socket deeper and thus increases the stability of the hip joint. On the other hand, the labrum “stands in the way” when the individual makes extreme hip movement. Recently surgeons discovered that damage of the labrum causes pain in the hip joint and successively leads to damage of the joint cartilage and possibly to the development of osteoarthritis of the whole hip joint.

UPPER PICTURE: The damage of labrum is caused by extreme bending movements in the hip joint.  The neck of the hip (collum) impinges on the rim of the acetabulum when the patient forcefully bends, rotates, and adducts the leg, for example bending the hip when taking off the shoe  or leaving the car as in these pictures. MIDDLE PICTURE :  NORMAL HIP – The schematic picture shows how the normal = sleek neck cannot reach the rim of the acetabulum and its labrum (violet triangle) even when the patient bends his/her hip joint. LOWER PICTURE: PATIENT WITH THICK NECK – Patients with a thick neck are at danger to damage their labrum. The thick neck of the hip joint in this schematic picture comes in contact and impinges on the labrum when the patient flexes and adducts forcefully the leg. Repeated impingements eventually lead to damage of the joint cartilage and development of osteoarthritis.

Impingement of collum against labrum  schematically Click on the icon for afull size picture

 How to arrive at the diagnose of this damage?

The signs of damaged labrum:  pain in the groin is the main sign of torn labrum. The precise site of pain may, however, vary considerably. Sometimes the pain can be so intensive that the patient is forded to use walking support. (Stephen 2006)

The  MRI of the hip joint completed with injection of contrast material into the hip joint (arthrography) is an effective method to show the damage of the labrum and also the damage that continues to the joint cartilage of the hip socket.

Arthrography of the hip joint is  is relatively small procedure, local anaesthesia is used only.

Show Picture:  MRI picture of the torn labrum of the hip joint.

On this MRI picture the radiologist injected the contrast material (the substance with the long word “gadolinium”) into the joint space of the hip joint. It is seen as a white line on the black background. The thick arrow in this picture shows the rupture through the labrum. The white contrast material squeezes into the rupture through the black labrum. The cartilage of the socket close to the rupture is already worn out and in its place there is the white contrast material. The small arrows that encircle the white pool of contrast material demonstrate the area where the socket’s joint cartilage is destroyed so that there is place for the contrast material.

Another diagnostic method is the keyhole inspection = arthroscopy of the hip joint. This is a rather "big" examination: the patient must be completely relaxed (good anesthesia is necessary), the leg stretched forcefully (about 25 kg stretching force) to produce space in the hip joint for the arthroscopic instrument. Smaller complications as temporary lesser nerve damages may occur after this operation. On the other hand the surgeon sees the damage directly and may remove the damaged part of labrum during the arthroscopic examination.

Damaged labrum (marked by arrows) as seen by arthroscope (Adapted from Stephen et al, 2006) Click on the icon for a full size picture

The treatment:

 If the diagnosis is clear, the surgeons remove the torn piece of the labrum. If the socket’s cartilage is damaged the surgeons remove the damaged parts of cartilage too.  Smaller ruptures of the labrum may be sutured. These operations may be carried out by a keyhole (arthroscopic) approach. (See the upper note).

When there is a deviant form of the neck of the hip joint, the surgeon may trim away the thick part of the neck (Collum). This is usually done in an open wound operation. The surgeon opens the hip joint, dislocates the head and neck of the hip and chamfers away the surplus part of the neck.  

The published results of this "big surgery" are surprisingly good: over 75% of patients were relieved of pain and did not develop damage of the circulation to the femoral head.

Reference with more details:

Stephen R et al: Clinical Presentation of patients with tears of acetabular labrum. J Bone Joint Surg-Am 2006; 88-A: 1448 -57

           EPIPHYSEOLYS   AND  PERTHES  DISEASE

Slipped femoral head and Perthes disease are two childhood /teenage hip diseases that may deform the femoral head permanently and lead to the development of a painful secondary osteoarthritis of the hip joint.

The skeleton grows from separate centers. For example the femoral head grows from a separate center which is attached to the rest of the thigh bone with a special growth (epiphyseal) cartilage. Two adverse things can happen:

Slipped femoral head.

The growth cartilage, which is a weak link,  may become soft and the fixation of the femoral head to the thigh bone will soften.The whole femoral head will glide (slip) on the thigh bone.  The softening of the growth cartilage is probably caused by some hormonal imbalance during the growth period and sometimes a trauma is also involved.

The treatment of this condition is by pinning the slipped femoral head to the thigh bone and  by protected weight bearing. The circulation in the slipped femoral head may be still jeopardized and a part of the head will die, in spite of pinning. This is  an avascular necrosis of femoral head. Usually the avascular necrosis leads to deformation of the femoral head and to development of a late secondary osteoarthritis.

Perthes disease

named after the German surgeon who first described this condition- is an avascular necrosis of the growing femoral head. The cause is unknown. The avascular necrosis may   heal and the femoral head retain its round form, or the necrotic head may deform and this deformation will lead to the development of a late secondary osteoarthritis.

Treatment is by protected weight bearing and by osteotomy operation if the necrotic lesion is small to relive the growing head from weight bearing.

(9) FUSED  HIP JOINT

The fusion of the hip joint was a common operation up to 1970's. These patients seek conversion to total hip replacement usually because of pain in the other hip, low back and knees.

Conversion operation is a challenging surgery.

See more information in the chapter Candidate for total hip.

PREVIOUS INFECTION IN THE HIP

Some patients who as children have had bacterial joint infection, develop later painful secondary hip osteoarthritis. These patients are candidates for total hip replacement if

the infection is healed several years clinically (no drainage or swelling of the hip joint area)

blood test show no signs of infection activity

X-ray pictures show no areas  of chronic bone infection (osteomyelitis).

Still, the original infection is never healed, it is only sleeping and it can be awaken to life by the total hip surgery.

The results of THR after previous hip infection depend on the bacteria that caused the original joint infection.

The lowest rates of recurrence of the original infection have patients whose hip infection was caused by Gram-positive bacteria, followed by patients with "healed" tuberculous infection. The worst results, with recurrence of infection in more than 20%, have patients with joint infection caused by Gram-negative bacteria.

(Gram-positive and Gram-negative refers to the staining properties of bacteria discovered by the Danish bacteriologist H. C.  Gram)

The leg of these patients is usually shorter, the hip has often a contracture (bent forward and pushed inside - adducted). Sometimes, the hip is fused, either spontaneously, or by a fusion operation.

These changes put a strain on the lower back and these patients have often also symptoms from the spine.

Operation of a fused hip joint is a challenge. (See also Candidate for total hip operation)

The risks with  operation of a previously  infected hip joint:

• The surgeon may discover a core of  active bone infection during the operation, containing pus and rests of necrotic bone. Most surgeons will not continue with total hip replacement in this case. They will take away all infected tissues, put a drain and perhaps also chunks  of bone cement with antibiotics into the wound and start leg traction. They will put the patient on large doses of antibiotics, the choice will depend on the result of the bacteriological cultivation.This treatment may take months, the patient will be most time on crutches. First  when this infection has healed the surgeon  can contemplate a new attempt at total hip replacement
• The original infection may flare up after total hip replacement. To prevent this the patients are usually put on a long regime of antibiotics.
• There is a risk connected with long-term antibiotics treatment: It  may produce successively antibiotics-resistant bacteria; and it may produce side-effects in the patients, many of them may be serious or even lethal (necrotising bowel inflammation).
• The function in the hip muscles is usually difficult to assess before the operation on the largely immobile hip. After the operation, with the mobile hip, it may appear that the muscles have low strength. This muscle insufficiency may cause limp and  joint dislocation.

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(10) ANKYLOSING  SPONDYLITIS

is an inflammatory disease affecting  the whole spine and hip joints, but also other joints. The whole spine fuses successively, the fusing process starts in the small joints between pelvic bones (sacroiliacal joints) and continues upwards. Eventually, the whole spine from the back to the neck is solidly fused.

In some patients, one or both hips show severe damage. The fused spine is not painful, the hips are painful and stiff.

The X-ray pictures of the spine are typical and make the diagnosis.

There are also some specific laboratory markers (HLA antigens) present in some of these patients.

This is a disease of young people.

Stiff hip  joints increase the patient's handicap and the surgeons have been  attempting the   total joint replacement of one or both hips in these patients.

Because of severe damage of the whole  spine in these patients, inclusive of the cervical spine (neck spine),   there may be  problems with anesthesia in these patients. Consult always the anesthesiologist with X-ray pictures of the whole spine (from the low back to the neck)!

These patients may be also prone to develop heterotopic ossifications around the total hip.

Although some surgeons were concerned that the loosening rate of total hips would be high in these young patients, the published results are encouraging:

After 15 to 25 years, 85% of all operated patients consider the result of the total hip replacement excellent;   80% of the original total hips were still in function after 20 years.

The mean age of these patients at the operation was 40 years, and two thirds of the patients have had both hips replaced (Sweeney 2001, Joshi 2002)

Before you take any decision, please read carefully the Disclaimer

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