Total Hip Replacement Surgery
Hip replacement surgery dates back almost one hundred years. The first attempts at replacing the joint were far from successful and were based on naïve mechanical principles and grossly inferior non-biological materials.
The real precursor to the modern hip replacement was first introduced by Professor Sir John Charnley in the late 1950s and early 1960s. He used a metallic stem in the upper end of the thigh bone made of stainless steel and a type of plastic liner in the acetabulum or pelvic socket. The first acetabular component was made of Teflon and, although it was of very low friction, unfortunately it did have a very high wear rate. The debris so liberated in the region of the hip joint gave rise to the formation of massive pseudotumours. This is where your own body mounts a response in an effort to gobble up these microscopic pieces of plastic and, in turn, forms a very large tumour in the groin. He had two or three hundred such patients and I remember his widow telling me that, during the early 1960s when they had to be removed, both he and she experienced the worse times of their lives. This was a very traumatic time for everybody.
The next major step forward was to replace the Teflon with polyethylene. Even today in 2016 we still use a type of polyethylene to line the hip socket.
Modern materials now include titanium, cobalt chrome, ceramic and highly cross-linked polyethylene.
There are more than 150 types of hip replacement available. They vary in size, shape and material construct. All of them aim to replace what is normally a painful arthritic joint between the ball and the socket with artificial materials.
The hip replacement surgery involves hospitalisation, an anaesthetic and an operative exposure of the joint. Varying lengths of stay are required following these operations but most patients are discharged within seven days.
The hip can be approached through the front, the side or the back. Much emphasis is placed by some people upon the operative approach that is used. In essence, they all yield much the same result. There is an old saying that, “No matter which airline you fly with, provided you just get there”. This probably also applies to the approach used for the hip replacement.
Complications can occur. Fortuitously, they are quite uncommon. They include problems with the anaesthetic and may even be as severe as death. Stokes can also occur. At a local level, we are concerned about infection, damage to arteries or nerves, fractures of the bones, clots travelling off to the heart and lungs and excessive bleeding.
Hip replacements are now vastly more successful than they were in Charnley’s day. Our registries show that 90% of well-performed total hip replacements will still be functioning in twenty years’ time. Obviously not all of them fall off the perch at twenty years and one day. Some may function for thirty or forty years or even longer. The survivorship of the joint will depend a great deal upon the biology of the patient, the way the hip replacement is used and the competence of the surgeon involved. These are just three variables of many. Whilst hip replacements are performed regularly all over the world every day, it is a serious and important operation. It should be treated so.
Revision Hip Replacement
Unfortunately, not all hip replacements will last indefinitely. Whilst a well-performed hip replacement can expect to have a survivorship of 90% at twenty years, some replacements will fail sooner than others. Reasons for failure include infection, aseptic loosening, excessive wear, recurrent dislocation or fractures around the implants that have been used.
Revision hip surgery is more complex than primary hip replacement surgery. This is because the tissues are scarred and damage has been created in that area giving rise to the eventual failure of the joint, and the risks are therefore increased concomitantly. Sometimes a revision can be quite straightforward and only one part of the joint requires replacing. At the other end of the extreme, the entire joint has to be replaced and significant bone grafting or the use of supplemental materials is also invoked. The risks of infection, damage to arteries or nerves, fractures, clots and haemorrhage are all increased.
This is a special part of orthopaedic surgery that has formed the basis of a sub-specialty. Some surgeons perform more than others. There is an old saying that good orthopaedic surgery comes from experience. Experience comes from bad orthopaedic surgery. You may consider asking your surgeon about his or her experience and competence with this special branch of hip surgery.
Hip Preservation Surgery
The term “preservation” refers to the concept of keeping the patient’s own ball on the upper end of the thigh bone and own socket in the pelvis. Whilst the joint itself may be diseased in some way, there may be surgical methods available which can alleviate the discomfort and malfunction associated with the disease but still keep the hip intact.
This refers specifically to arthroscopic surgery or surgery involving osteotomies or division of bones aimed at redirecting the weight bearing forces within the joint.
Arthroscopic surgery can be accomplished under a general anaesthetic in an operating theatre in a day surgery environment. Two or three small nicks in the skin are required to insert the telescope bearing the camera and other instruments that can be used to smooth, trim, shave or even remove some bone or loose bodies from a joint. This arthroscopic surgery can be extremely successful when used for the right indication in the right patient by the right surgeon.
The other type of hip preservation surgery relates to osteotomies or the division of bones. Whilst the ball and socket themselves are not interrupted with the osteotomy, the socket could be re-aligned or redirected, as could the upper end of the thigh bone and its ball. What was once a mal-aligned joint can be re-aligned. Whilst the wear that has occurred can not necessarily be reversed, the rate of demise of the joint thereafter can be appreciably slowed. A good analogy would be a motor vehicle that requires a wheel alignment. As a result of the abnormal alignment, the front tyres had been scrubbing and wearing eccentrically. After the wheel alignment, that tread does not regrow obviously but the rate at which the tread wears thereafter is dramatically slowed. Similar feats can be accomplished around the hip joint with this hip preservation surgery.
Arthroscopic Labral Repairs
The term “arthro” refers to the joint and the term “scopy” refers to a telescope that can be put into the joint. The labrum is a cartilaginous or soft flange that forms the edge of the hip joint socket.
There are some circumstances where these labral tears or detachments are symptomatic and can be repaired.
Skilled hip arthroscopists are able to accomplish this feat through two or three small nicks in the skin. This is often performed as a day case and, by re-attaching or reconstructing the labrum, pre-operative symptoms can be dramatically diminished or even eliminated.
It is also possible that by re-attaching or repairing a labrum, the rate of demise of a joint which was destined to become arthritic can be dramatically slowed. It is possible that the longevity of the joint can be increased appreciably.
Extra-capsular Arthroscopic Procedures
Not all abnormalities around the hip joint require open operation for correction.
There are occasions when tendons can be released, fluid-filled sacs can be drained, or those sacs (bursae) can actually be removed. Conditions that can be successfully managed arthroscopically include iliopsoas tendinopathy, iliopsoas bursopathy, gluteal tendinopathies and greater trochanteric bursitis.
The term “osteotomy” refers to division of bone. It is something like a controlled fracture. The biology of bone is marvellous. If the controlled fracture or osteotomy is performed satisfactorily, and post-operative management is exemplary, the osteotomy will eventually heal. It means, however, that the direction of weight bearing forces can be altered by changing the direction in which the bone points or faces.
These osteotomies can be used on the pelvic side of the joint or on the thigh bone or femoral side of the joint. Sometimes osteotomies can be performed on both sides, either separately or simultaneously.
The goal of these osteotomies is to improve the biomechanics of the hip joint itself.
Assume, for example, that the socket is too shallow, is too large or is facing in the wrong direction. The weight bearing forces transmitted to the ball are abnormal in magnitude, abnormal in direction, and will tend to excessively wear one small part of the ball in preference to others. This is how osteoarthritis can start and progress. By changing the size, the direction or the inclination of the socket, those forces can be very dramatically reduced. Successful osteotomies around the socket can reduce the symptoms experienced by a patient, can retard the rate at which any form of arthritis process may develop, and give rise to an extremely satisfactory outcome in a well-chosen subject.
Similar concepts apply on the thigh bone or femoral side of the joint. Load bearing forces can be redirected, can be changed in magnitude, and can be used as friends rather than foes.
Whilst osteotomies around the hip joint are performed far less commonly than say thirty or forty years ago, they still have a very important role to play. Surgeons who specialise in hip surgery specifically are usually well skilled in this particular area.