REVISION HIP REPLACEMENT
While total hip replacement is one of the most successful operations, after a period of 10 – 15 years it can fail like any mechanical device. This may require further revision surgery which is often a more complex than a primary total hip replacement (first time hip replacement). Revision surgery is technically difficult and often involves removing the old hip replacement and replacing with a more complex hip replacement. The surgeon also has to restore the bone stock with bone grafts or special artificial materials.
As more and more younger people are being offered hip replacements and the number of hip replacements are increasing, it is likely that the number of revisions will also increase in the future. Mr.Ganapathi employs up-
There are several ways in which a total hip replacement can fail including:
With time, the plastic in the cup side of the total hip replacement becomes worn out. In that process tiny plastic particles are produced to which the surrounding tissues react. This reaction leads to the bone getting gradually eaten away (lysis) leading to loosening of the hip replacement. The hip becomes painful. Pain can be present in the hip in the region of the groin or it can present as thigh pain. Sometimes the loosening may be relatively asymptomatic for a long time and becomes only very symptomatic when there is large amount of bone destruction which makes the revision procedure even more complex. This is one of the reasons for regularly following the hip replacement patients with x-
Loose Hip Replacement
After Revision Hip Replacement
The ball of the total hip replacement may come out of the socket. This can occur at an early stage or at a late stage. There are a number of reasons for dislocation to occur. Usually it would be possible to put the hip back into the joint (often will need an anaesthetic). If the dislocation keeps recurring, it would be appropriate to consider revision procedure. Mr. Ganapathi was involved in a study analysing the financial aspect and functional improvement following in patients with first time dislocation of the hip. On a conservative estimate, the financial cost in subsequent management of 100 first time dislocating hips was over £500000 and the functional improvement was less than optimal. One of the reason for dislocation is the fact that the ball of the total hip replacement is much smaller than the native ball of the hip joint. This compromise was taken as the properties of the materials available in the past did not suit larger size heads. However, there are various modern material available (like metal, ceramic and special plastics) which allow a bigger size ball to be used during the hip replacement. Studies have shown that the there is less dislocation rates as the ball size increases. The UK national registry also shows that there is an increasing trend among the hip surgeons to use relatively larger ball in the recent years.
Dislocated total hip replacement (with bone loss and loose cup)
Large area of bone defect in the acetabulum (cup)
Bone defect sequentially filled with trabecular metal augment and trabecular metal shell
ray after the revision surgery
What is trabecular metal?
This is a porous structure made of Tantalum and has better bone-
Trabecular metal structure (Zimmer)
Infection following hip replacement is a very rare complication. It can occur soon after surgery (early infection) or many years after the hip replacement (late infection). Early infection can be superficial or deep. While the former may respond to antibiotics, the deep infection will need further surgery in the form of washout or revision procedure. Late infection can occur at anytime throughout the lifetime due to bacteria (bugs) entering the blood stream from infection in other parts of the body. If this happens, the hip replacement gradually gets loose and the hip becomes painful. Although it is a challenging problem, majority of the patients could be treated by revision surgery. This usually is a two stage procedure with the first stage being removal of the infected hip replacement and insertion of temporary spacer and treatment with antibiotics followed by second stage with a definitive hip replacement (when the infection has settled – usually after 3 months).
A technique to make the first stage implant (using a mould)
ray showing the first stage implant in place
This is a rare complication following hip replacement. The bone fractures (breaks) around the vicinity of the hip replacement. Depending on the type of fracture, this may be treated by internal fixation or by further revision surgery with a complex hip replacement.
1 year after revision surgery using a long stem (the fracture has healed)
This can occur in some cases of uncemented implants if there is not enough host bone contact with the implants (usually in the acetabular component) or if there is not enough vascularity for the bone growth to occur. Special materials like trabecular metal (made of tantallum) are now available which have a porous structure similar to cancellous bone and has better osteointegration properties than conventional titanium implants and hence being increasingly used in revision hip replacement.
Hybrid hip replacement done few years ago
The patient presented with increasing pain in the hip. X-
ray revealed the cup has come out of the socket along with dissociation of the liner
CT scan also revealed bone loss posteriorly
After complex revision surgery using a cage to compensate the lack of bone support due to bone loss
This is quite a challenging problem and more commonly associated with lateral approach. Often the failure is due to the fact that the abductor muscle is quite weak and is not able to hold the sutures. This can give an abnormal gait and in addition, this can also be a factor resulting in recurrent dislocation. Revision surgery often involves some form of constrained/captured device to hold the ball in place. While it may be possible to reattach the abductor muscle, it is not always successful.
ray showing dislocation (the ball is out of the cup)
Charnley hip replacement done few years ago. Had recurrent dislocations and was also walking with Trendelenburg gait suggesting abductor failure/weakness
operatively it was found that the abductor has completely failed to
Cup revision was done with constrained cup and abductor repair done with a reinforcing mesh.
The following are some relevant selected scientific references:
3. Prevalence of primary and revision total hip and knee arthroplasty in the United States from 1990 through 2002.