THR - Total Hip Replacement

 

Technicalities

 

 

 

The hip joint is like a ball and socket, the ball part (femoral head) is at the top of the leg bone or femur, the socket, called the acetabulum, sits in the side of the pelvis. The acetabulum is replaced with a new socket comprising of a shell and liner, and the femoral head is replaced by a femoral stem that is inserted into the femur to support a new femoral head component.

 

                            

Acetabular shell                      Acetabular liner         Femoral head               Femoral Stem

 

 

There are two main classes of hip prosthesis, cemented and uncemented, there is also a hybrid which is a cemented stem with an uncemented cup.

 

In the cemented types, a special cement such as polymethylmethacrylate (PMMA) is used to fix the prosthesis.

 

In uncemented types, the bone is allowed to grow into the surface of the prosthesis, these are often given a special coating of bone-like material such as Hydroxyapatite to encourage growth.

Titanium screws are often used to secure the acetabulum to the pelvis, whereas the stem is usually a press fit in the hip bone.

 

The main types of materials used are metal, ceramic and polyethylene in various combinations, these are not 'common' metal, ceramic and plastics, but very high grade surgical materials.

 

Common material combinations

Head	Liner
Ceramic	Ceramic
Ceramic	Plastic (Ultra High Molecular Weight PolyEthylene)
Metal	Plastic (polyethylene)
Metal	Metal (Largely discontinued due to problems)

 

 

The combination of materials and fixation will be decided by your consultant and will depend on many factors such as your age, activity level and bone condition. 

 

The surgical approach is divided into three main types, Posterior, Lateral or Anterior.

Posterior - The surgery is performed from the rear of the leg.

Lateral - The surgery is performed from the side of the leg.

Anterior - The surgery is performed from the front of the leg.

 

 

Medical jargon

Distal (latin 'distare') is distant to the main torso, so the distal femur joint is the knee.

Proximal (latin 'proximus') is nearest to the main body, so the proximal femur joint is the hip.

 

 

Cemented

These tend to be faster to full mobilization of the patient, there is however a possibility of a bodily reaction or rejection of the cement.

 

Uncemented

These tend to be easier to revise at a future date, a significant advantage in younger patients, but tend to be slower to full mobilization of the patient until the bone growth into the prosthesis has established.

 

Metal on Metal bearing surfaces are no longer encouraged due to problems that have been encountered with metal particles being liberated into the blood and/or body over time.

 

 

Superpath

Is a minimally invasive procedure with no hip dislocation prior to surgery, and muscles are parted rather than cut. [Pansycat52]

 

 

Anaesthetics

A spinal is a specific amount of numbing solution, given to you with one shot into your spinal fluid. Then the needle is removed. This is best for surgeries where you know the amount of time it is going to take, for example Prostate biopsy.

An epidural is a drip, you have a smaller needle introduced into your spinal fluid and left there with tape. The anaesthetist can control how much you need for a much longer surgery, which is why it is standard for women giving birth.

Depending on where they administer the solution, it can numb just certain parts of your body; one place for your chest, one place for your hip, depending on the nerves that need to be numbed. [luvinlex]

 

 

FRCS - Fellow of the Royal College of Surgeons of England. The surgeon's education and training, professional qualifications, and surgical competence have passed a rigorous evaluation, and have been found to be consistent with the high standards established and demanded by the College, of which the surgeon is a current Fellow.

 

MRCS - Member of the Royal College of Surgeons of England. The surgeon is in training and has achieved a level of generic surgical competencies that enables him to successfully undertake specialist training, and he is a current Member of the College.

 

 

 

 

 

Walking Gaits

There are various definitions of walking gaits which you may hear of, most of these are unlikely to be due to pains following total hip replacement. Click on the names for videos and explanations of each one by Dr. Nabil Ebraheim, M.D., Department of Orthopaedic Surgery, University of Toledo Medical Centre, Ohio, USA.

 

Gait	Symptoms	Common causes
Trendelenburg	Pelvis drops on one side.	Weak abductor hip muscles.
Antalgic	Wanting to spend as short a time as possible on the affected painful leg.	Pain in the leg.
Slap or Steppage	Foot is slapped down.	Weakness in the foot and ankle.
Gluteus Maximus	Body lurches backwards as you walk.	Weak gluteus maximus muscle
Wide Based or Myelopathy	Staggering wide-based movements	Nerve damage
The value of the cane	Video about use of the cane or walking stick

 

 

 

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If you are not a healthcare professional then you should ALWAYS check with your doctor if you have any concerns about your condition or treatment and before taking, or refraining from, any action on the basis of the content on this Website.

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Contact: Webmaster (at) thr. org. uk

Page last updated: 4 August 2016