Hip replacement surgery is a procedure whereby parts of an injured or affected hip joint (ball and socket) are removed and replaced or reconstructed with a new artificial prosthesis. The surgery is also known as hip arthroplasty, which means shaping or forming. The prostheses can consist of plastic, metal and ceramic.

3D hip replacement surgery is a procedure that uses a custom-made 3D-printed hip prosthesis that fits the patient’s anatomy unlike the traditional hip replacement which tends to be off-the-shelf. It has a unique personalized design that is based on the patient’s hip CT scan.

The procedure, which is usually performed for total hip replacement surgery involves replacing a patient’s damaged hip joint with one that mimics the natural motion of the hip.

Getting the hip replacement personalized and sized correctly involves taking CT scans of the hip joint. The image-to-implant software platform uses this information to convert the 2D CT scan into a 3D model of the patient’s hip by mapping the contours of the bone and correcting the areas damaged by disease or trauma. A total hip joint implant is then fabricated to fit the exact contour and shape of the hip.

Traditional hip replacement surgeries offer a fixed design in different sizes meaning they offer the ‘best fit’ rather than a personalized fit. A custom 3D hip replacement on the other hand feels so much like the patient’s natural hip and works in unison with the patient’s ligaments and tendons. It therefore provides a more rapid recovery with good range of motion restoration and natural biomechanics.

Ideal Candidate for a Custom 3D Printed Hip Replacement

Active patients who are eligible for a hip replacement surgery are suitable candidates for the custom hip replacement. However, patients with large bone loss or severe bone deformity are not good candidates for this procedure. The best candidates are active and motivated individuals.

Factors that Lead to Hip Replacement Surgery

Osteoarthritis: This is a condition that occurs as a result of cartilage breaking down around the areas where the ends of an individual’s bone meet his/her joints. During the disintegration of the cartilage, an individual’s joint begins to rub together causing pain, inflammation and swelling.

Damaged hip joint: Another common factor that leads to hip replacement is damaged hip joint which can occur due to fractures and bone tumors. This kind of joint damage can be effectively repaired with surgical intervention.

Rheumatoid arthritis and osteonecrosis: This is a medical condition that develops causing an individual’s immune system to begin attacking the membrane that lines his/her joint. The condition is characterized by inflammation, stiffness, and pain.

Traumatic arthritis: This is when one has suffered trauma that causes injury to the hip joint.

Risk Factors of 3D Hip Replacement Surgery

Even though complications of hips replacement are rare, less than 2% of individuals who undergo the procedure may experience the following complications:

• Infection
• Blood clots
• Possibility of leg inequality
• Nerve and blood vessel damage around an individual’s hip area
• Deep vein thrombosis

Conditions Ideal for 3D Hip Replacement Surgery

There are certain instances whereby 3D-printed hip replacement is the ideal procedure. These include:

Femoroacetabular Impingement (FAI)

FAI can be treated using osteochondroplasty (reshaping deformed femoral head) to remove the excess impinging bone from the neck junction of the femur. Here the CT-based surgical planning is conducted to design a femoral head and neck jigs which are 3D-printed and act as a guide for adequate and optimum excision of bone at the femoral head-neck junction.

Osteonecrosis of Femoral Head

In early treatment of osteonecrosis of the femoral head, a conventional method of core decompression is performed. This is normally done under C-arm fluoroscopy. The 3D-printing guide is attached to the proximal part of the femur during the operation and Kirschner wire is inserted into the pinhole on the guide plate to obtain an appropriate decompression position.

Total Hip Arthroplasty

Patient-Specific Instruments (PSI) is used to guide the positioning of components during hip arthroplasty. PSI systems are custom-made on a case-by-case basis, specific to both the anatomy of the patient and the surgical plan made by the Orthopedic surgeon.

CT-scan and magnetic resonance imaging are used in the surgical planning of a virtual 3D environment. Acetabular guidance systems are mainly purposed to optimize the cup size, implant medialization, anteversion, and inclination. Femoral guidance system stems optimize the stem size and alignment, offset leg length, and stem version.

During orthopedic procedures involving 3D hip replacement surgery, the orthopedic surgeon integrates all preoperative 2D images and formulates them into the 3D-surgical plan. For surgeries involving the hip and pelvis, preoperative planning can be difficult especially in cases of complex anatomy and severe deformity.

3D-printed anatomical models provide medical specialists with an opportunity to understand individual patient anatomy. It also enables surgeons to develop better surgical approaches, tests, testing the feasibility of procedures, and determining the optimal location and size of implants.

Post-operative Care

After the 3D hip replacement surgery, the patient can remain under observation in the hospital for up to 10 days (or longer depending on the patient’s overall condition). During this time, antibiotics and pain medication, and fluids are administered to the patient intravenously. These medicines are for relieving pain, preventing infection and blood clots.

A physiotherapy with the assistance of a therapist is recommended in the first 5 months after the surgery to ensure faster and safer recovery. Normal activities may be resumed 10 weeks after the procedure, but this varies from one patient to the next.

Benefits of Custom 3D Hip Replacement

There are certain advantages associated with custom 3D hip replacement and they include:

• Decreased levels of bone cutting during the procedure
• Improved fit of the hip joint prosthesis
• Preservation of the hip’s natural joint line and shape
• The option of using custom hip replacements for partial joint or total joint replacement

Patients report a 95% satisfaction rate with the custom hip replacement compared to 80-85% of the off-the-shelf hip replacement.