POTENTIAL COMPLICATIONS OF HIP REPLACEMENT
Deep Venous Thrombosis(DVT)
All major lower limb and pelvic surgery is associated with a risk of deep venous thrombosis. A thrombosis is a clot within the deep veins of the calf, thigh or pelvis of the patient.
Measures we employ to reduce this risk are the use of surgical stockings which compress the deep veins emptying them of blood during stocking use.
We also utilise a low molecular weight heparin. This reduces the ability of the blood to clot by a small amount.
During surgery we utilise a pneumatic compression device which massages the calf of the patient and reduces the risks of clot formation. Despite measures employed to reduce the risk it is never completely eradicated.
On discharge we perscribe an oral anticoagulant - Rivoroxaban - to further reduce the risk of DVT.
Pulmonary Embolus (PE)
The formation of small clots within the deep veins of the calf, thigh and pelvis can be associated with a pulmonary embolus. Portions of the deep venous clots become detached and circulate through the venous system back to the heart and then on to the lungs.
Here they block vessels and prevent the lung from delivering oxygen to the blood on its return to the heart.
Again the combination of surgical stockings and a low molecular weight heparin are both used to reduce the risk of this occurring.
There is a lot of speculation to the true rate of both DVT and pulmonary embolus following major lower limb surgery during hip and knee replacement.
Treatment for either DVT or PE requires the use of a medicine to reduce the bloods ability to clot and to help dissolve the existing clot. This medicine is Warfarin and it is used typically for 6 months.
Fatal Pulmonary Embolus
In a very low proportion of cases a pulmonary embolus may be large enough to be fatal. The incidence of this has been reported as being in the order of 0.34%.
Despite all the techniques employed in modern day joint replacement there remains a risk of infection with all modern day joint replacement.
This risk is low and the risk of a deep infection is generally quoted as being less that one (1) percent i.e. 1 in 100 cases.
Hemorrrhage and Haematoma
All surgical procedures result in bleeding (hemorrhage). At the end of the surgical procedure we use a drain to collect the blood which accumulates following surgery.
This drain appears as a small plastic tube exiting through the skin at the end of the operation. This will usually remain in place for 24 hours following the operation.
The drains we use are designed in such a way that the blood they collect can be returned to the patient to improve their post-operative recovery and reduce the requirement for a blood transfusion.
Very rarely, less than 1 percent of cases, the drain will fail to collect all the blood from the deep tissues.
A collection of blood in the deep tissue is known as a haematoma. In the majority of cases this will be small and will drain on its own typically via the vacant drain site.
In very rare instances a haematoma would be large enough to require drainage with surgery.
The hip has both blood vessels and nerves around it. During hip replacement instruments are placed to retract the soft tissues and saws are used to remove the neck and head of the thigh bone as well as to fashion the socket ready to take the new socket.
Whilst great care is taken to protect the tissues there is always a risk to both the blood vessels and nerves.
A variety of approaches may be undertaken to gain access to the hip joint for surgery.
We utilise a posterior approach which allows direct visualistion of the main nerve to the thigh and allows its protection during surgery.
The new hip replacement may rarely come out of joint and when this occurs this is known as dislocation.
The rate of dislocation will vary from surgeon to surgeon.
Patients are usually instructed post-operatively by the physiotherapists in activities to avoid which might lead to dislocation.
These are thankfully few and hip replacement gives a return to a great deal of freedom and pain free range of movement of the hip.
The use of larger diameter head sizes has a significant effect on reducing dislocation.
The new hip we utilise is a press fit variety. Pre-existing weakness in the bone and the need to press fir the components during surgery may lead to a fracture.
Typically this is of the thigh bone but can involve the socket.
The incidence of this is very low.
Occasionally this may not be realized until after surgery on the post-operative check x-ray.
This may effect the amount of weight the patient is allowed to take through their leg following the surgery.
In a large number of cases the fracture heals well on its own with no further intervention.
Leg Length Discrepancy
During the operation for hip replacement patients lie on their side. We employ a number of checks to determine their leg length and ensure that both legs are the same length after surgery.
In those patients who may require both hips to be replaced then following the first surgery they may notice a difference between the operated and unoperated side.
This is then corrected at the time of the second operation.
Occasionally in patients with severe deformity of the hip there may be a significant leg length discrepancy already.
Whilst every effort is made to equalize leg lengths during surgery in these cases this cannot be guaranteed due to the risks of permanently injuring the blood vessels and nerves around the hip.
Loosening and Revision
The majority of hip replacements utilise a metal ball articulating within a plastic (polyethylene) liner within the socket.
Over many years this plastic liner wears generating wear debris. This wear debris causes loosening typically of the socket component but also of the stem component were it attaches to the bone.
When this occurs patients present with new symptoms. The components will then require a revision hip replacement.
Modern bearing surfaces include ceramics as well as metal. Ceramic replacements tend to beused in younger more active patients to extend the lifespan of their joint replacement.
The lifespan of a joint replacement varies from individual to individual and would need to be discussed on an i dividual basis.