Partial Hip Replacement Vs Total Hip Replacement

Due to the evolution and the success of a total hip replacement in the past decades, partial hip replacement is performed in a very small subset of patients. Partial hip replacement involves the prosthetic replacement of the femoral head with a prosthetic stem and head. The socket of the hip joint formed by the acetabulum is not replaced in partial hip replacement.

Candidates for Partial Hip Replacement

Partial hip replacement is mostly performed in elderly patients with multiple diseases and limited mobility. The surgical time of partial hip replacement is shorter with less blood loss as compared to a total hip replacement. The partial hip replacement surgery typically lasts just about an hour. As the surgery time is shorter, the complications associated with a major surgery such as hip replacement may be decreased.

Partial hip replacement is also offered to patients who have limited mobility. During partial hip replacement, a larger prosthetic head of femur is used. The large size of the head provides greater stability to the prosthetic joint. A large prosthetic head requires a greater motion before it can pop out of the socket.

A partial hip replacement is also offered sometimes for patients with fractures of the neck of the femur. The neck of the femur not only connects the ball shaped head to the upper thigh bone but also carries vital blood supply to the head. The fracture of the neck disrupts the precarious blood supply and may lead to bone death of the head of the femur.

These patients may require a hip replacement surgery and if the socket does not show any arthritic changes, a partial hip replacement may be offered to these patients.

Types of Partial Hip Replacement

Unipolar and bipolar are two types of partial hip replacement. The unipolar replacement is rarely performed and most of the partial hip replacement surgeries are bipolar. In a bipolar hip replacement, the prosthetic head of the femur actually consists of two balls. A smaller metallic ball rotates inside the larger metallic ball. A high grade polyethylene plastic covers the inner metal ball to provide a smooth rotating surface.

Compared to bipolar, a unipolar partial hip replacement only consists of a head firmly attached to the stem of the prosthesis. The bipolar design provides greater stability, movement and also helps protect the articular cartilage. The ball in ball design mimics the socket of the total hip replacement.

Procedure

Similar to total hip replacement, a partial hip replacement may be performed under general anesthesia or spinal anesthesia. The surgeon may access the joint from the more commonly used posterior approach. The surgeon may also utilize robotic techniques or use minimally invasive techniques.

After a skin incision the surgeon reaches the joint after cutting or separation of the various tissues. The surgeon then removes the diseased head of the femur. The acetabulum is not reamed or prepared in partial hip replacement.

The surgeon proceeds to ream and prepare the femoral canal. The canal is prepared by serial introduction of special instruments known as broaches. Special attention is paid to the angle of the preparation. After a trial, the final prosthesis is introduced. The prosthesis may be press fitted or may be cemented in the femoral canal.

A bipolar prosthetic head is then placed on the prosthetic stem. The head is introduced back in the socket using a maneuver. The implant is again assessed for stability, movement and leg length. The incision is closed in layers and the patient is shifted to the recovery area.

The patients are placed on deep vein thrombosis prophylaxis and are up and able to walk with support the next day of the surgery. As surgery time is shorter than the total hip replacement, the recovery is accelerated.

Total Hip Replacement benefits over Partial Hip Replacement

Partial hip replacement has fallen out of favor to a total hip replacement and only a very small number of patients in the US receive a partial hip replacement. The hip joint is a large ball and socket joint. The socket is formed by the acetabulum, a part of the pelvic bone.

Both the head of the femur (ball) and the acetabulum (socket) are covered with a protective tissue known as articular cartilage. The articular cartilage functions to lubricate the motion of the opposing bones. Arthritis of the hip joint leads to damage of the articular cartilage of the ball as well as the socket.

Replacement of only the ball of the joint as in the case of a partial hip replacement leads to stress over the natural articular cartilage of the socket. The artificial surface of the prosthetic head rubs against the socket cartilage leading to progressive pain.

The majority of the patients have an active lifestyle after hip replacement surgery, and continued stress and motion over the socket cartilage leads to it’s damage. Therefore partial hip replacement is not recommended in patients with active lifestyle.

A total hip replacement involves the replacement of both the ball and the socket of the hip joint. The artificial joint allows greater movement and reduction of pain. The patients can freely move and play sports they enjoy after a total hip replacement.

A total hip replacement today may last for 20 years or more and in some patients a lifetime. Owing to the success and longevity of the implant, total hip replacement has today replaced most of the partial hip replacements.