REVISION HIP SURGERY

Revision Hip Surgery is the removal of an existing hip replacement and its replacement with a new (revision) hip replacement.


Revision hip surgery is far more complicated and more time consuming than first time (primary) hip replacements.

The outcome of revision hip replacement is often less satisfactory than the primary procedure due to a number of factors and, with each subsequent revision the result for the patient becomes less satisfactory. 


A hip replacement will require revision for a number of reasons, but these can be broadly broken down into:

1. Aseptic Loosening

2. Early infection

3. Late infection

4. Dislocation

5. Bone loss

As a result of the different ways in which the primary hip replacement can fail the method by which the revision is undertaken will vary as well as the type of new hip replacement used.

a


ASEPTIC LOOSENING

This is the commonest reason for revision hip surgery after a primary hip replacement.  


As a result of wear of one or both hip components the primary hip replacement will require revision.

The commonest reason for revision is aseptic loosening of the cup component in either cemented or uncemented cups. 


The stem may also loosen as wear debris from the socket causes loosening of the stem. 


Patients may experience one or more of the following: 

a)     Pain,

b)     Symptoms of the hip giving way,

c)      Persistent dislocation,

d)     Leg shortening

e)     Reduced range of movement

Some patients with loose components may present as an emergency following a fracture around the old components, after a relatively minor injury. 


They may have had one or several of the above symptoms prior to this on reflection. 


The time that it will take for a primary hip replacement to become loose due to aseptic loosening will vary immensely.

As previously stated the majority of implants have an average life expectancy of 15 or more years. 


Some components last less time however and factors such as patients’ age at the time of original surgery and how they use their hip replacement, will also effect how long it will last.

One or both components (the cup or stem) may need to be changed.

Even if a component is not loose it may require revision at the time of surgery. 


Reasons for this may include that the socket may be worn down by erosion by the metal ball on the stem in an uncemented cup design, or the stem may be damaged and this can indeed occur at the time of the revision itself, the ball may be scratched and damaged or in the case of a ceramic ball it may be cracked.

Loose components are easy to remove.

If the original component was a cemented hip replacement, the surgeon will need to decide whether to remove all the old cement and insert a new uncemented hip or whether to leave the existing cement and insert a new cemented hip with fresh cement.

The extent of bone loss is what can make reconstruction difficult. 


Bone loss can occur both in the thigh bone as well as around the socket as a result of aseptic loosening.

The surgeon will decide, based on his clinical experience and the degree of bone damage present, on the best form of reconstruction.

EARLY INFECTION (Occurring within 3 months)

a

An early infection after a primary hip replacement is not common. 


Unfortunately infection remains a possible complication of all surgery and even with all the measures taken to eradicate the risk of infection in modern hip surgery the risk remains. 


The signs of early infection include:

a) Persistent drainage from the incision site.

b) Persisting wound redness

c) Aching pain in the hip

d) Fever

e) A wound that bursts open, having been dry.

The management of an early infection firstly requires investigation to confirm the infection and then further surgery.


Investigation will include blood tests both before and after surgery.

a

The surgery will include a thorough washout of the wound and possibly changing some of the parts of the new hip replacement to further reduce the risk of infection recurrence. 


Post operatively the patient may well require antibiotics based on the pre-operative investigations and results from specimens taken at surgery.


If the treatment is early enough and aggressive enough then the primary hip replacement may be salvaged. 


Unfortunately if it is not, then the hip may go on to be chronically infected and will then require treatment for a late infection.

LATE INFECTION(3 months or later after surgery)

a

A small proportion of all hip replacements will present with late infection.  


Such patients may present anything from several months to a few years after their original hip replacement.

a

These patients may have been entirely symptom free and their hip replacement functioning very well for a period of time before they developed symptoms.

The signs of late infection would include:

a) Onset of pain in a hip that was previously pain free

b) Redness around the wound

c) Presence of an abscess or a discharging sinus

d) Fever & Ill-health

Once a patient presents with a late infection then a washout of the joint is seldom successful.


Removal of the infected joint is almost always necessary.  


This can be a difficult procedure if the hip replacement is well-fixed. However if it appears loose on the new X-rays, due to the chronic infection, then the infected joint may be removed with ease.

If well fixed, then significant damage to host bone can occur whether removing a cemented or a cementless implant. 

The operation should be done by an experienced hip surgeon with a specialist interest in hip revision surgery.

It is possible to insert a new hip immediately however this is associated with a significant re-infection rate. In the majority of cases a revision hip replacement fro late infection is undertaken in two separate stages.

In the majority of cases a temporary hip replacement, or Spacer, needs to be inserted while the infection is being treated (1st stage)

Treatment of the infection will depend on a number of factors.  


The type of organism causing the infection will need to be established and this is often accomplished by submitting samples for analysis at the time of surgery.   


Treatment of the infection traditionally rests in the use of antibiotics over a period of many weeks (6-8). The type of antibiotic will depend upon the infecting organism.

The ultimate type of revision hip replacement used after eradication of the infection (2nd stage) will depend upon the quality of the patients bone remaining and the type of new hip to be inserted (cemented or cementless).

The timing between the two operations is usually a minimum of 8 to 12 weeks but, may need to be significantly longer if the infection is slow to settle.   


Again blood tests will be needed to monitor the eradication of the infection.  Ultimately the decision to perform the revision replacement will rest with the surgeon.

a

RECURRENT DISLOCATION

This is a very disappointing complication of primary hip replacement in an often otherwise well functioning hip.  

Dislocation of a primary hip replacement can occur for a number of reasons:

a) Lack of patient co-operation

b) Slack soft tissues around the joint

c) Soft tissue impingement due to scar tissue

d) Mal-position of components- poor surgical technique

Dislocation can be very difficult to treat and where it occurs due to slack soft tissues or, lack of patient co-operation, then there is a high likelihood that the hip will continue to dislocate despite revision surgery. 

The operation can involve excision of scar tissue, repositioning of one or both components and re-tensioning of the soft tissues with new components.

BONE LOSS WITHOUT LOOSENING

This can be a totally asymptomatic process.It may occur behind cementless cups and can occur around the thigh bone component.

Although revision surgery can be fairly straight-forward when the socket is involved, re-operation can be a very major undertaking if well-fixed components in either the socket or in the thigh bone need to be removed.

Significant bone damage can occur during the removal process requiring reconstruction.

This is not only difficult for the surgeon but requires significant expertise.

THE OPERATION

Once it is established why the primary hip replacement requires revision then the surgeon will need to discuss with the patient the surgery to be undertaken. 

Each surgeon varies in their approach and whether they choose to use uncemented or cemented components for the revision.

The quality of the bone of the patient, their age, the training of the surgeon and their personal preferences all play a part in the selection of which new components will be implanted.

Surgery will require a general anaesthetic. 

The surgical approach will depend on surgeon preference and the previous approach for the primary surgery. Depending on the reason for revision the operation may be performed in either one or two stages as discussed above.

After the old components are exposed they will be assessed for whether they require removal according to whether they are damaged or just worn out or loose. 

The revision may require removal of one or both of the cup or stem components or, a new liner for an uncemented cup as well as a new ball on top of the stem if the components are well fixed.

Surgery may take from an hour to three hours according to its complexity. 

As a result the risks and possible complication rates are greater than for primary hip surgery. 

At the end of the operation a drain will be usually be used.

Depending on how the surgery is performed the patient may or may not be allowed to walk on their new hip replacement immediately after the operation and this may not become apparent until during the operation itself.


OUTCOMES OF REVISION HIP REPLACEMENT


Complete pain relief is less common in revision hip replacement than in first time hip replacements.


Complication rates are higher and include the following:  

1. Dislocation

2. Infection

3. Thromboembolism

4. Leg Length Discrepancy

5. Fracture of Femur

6. Nerve Injuries

7. Vascular Injuries

8. Heterotopic Ossification

9. Stem Breakage

10. Loosening

11. Wear

12. Revision

All these possible complications are the same as for primary hip replacement, although, the rates are all higher as a result of the extended time that such surgery will take in each patient and the further abuse to the patients soft tissues.

The overall result for the patient will vary a great deal according to why the patient requires revision.  


The subsequent complications will also vary according to the reason for revision.  


The overall results for revision surgery vary according to surgeon and institution.

Revision hip surgery requires significant expertise and should be undertaken by those with a specialist interest in such surgery performing such surgery on a regular basis.

It is time consuming both for the surgeon as well as the patient, complicated but overall with a satisfying result for the patient as well as the surgeon.  


With all this said however revision hip surgery usually removes well over 90-95% of the patients symptoms and they are as a result of it extremely satisfied. 


Compared to the symptoms they had from their failing original hip they are usually very pleased to have had the surgery and benefit greatly from it.


As with primary hip surgery it is a very satisfying operation for both the surgeon and the patient.