What is Zimmer THA?
Zimmer THA (total hip arthroplasty) is a hip replacement procedure in which the damaged or worn out articulating surfaces of the hip joint are removed and replaced with a state-of-the-art Zimmer hip prosthesis.
Zimmer’s hip implants are made of advanced technology with high-quality metals. The metal prostheses are made of forged metal and are different from the traditional hip components made of cast metal. The Metasul metal-on-metal technology used by Zimmer provides a high-degree of hardness, smoothness, and durability to the implant. Zimmer Trabecular Metal Hip Technology stimulates the body’s spongy bone to produce a high degree of friction that helps stabilize the hip joint after implantation and also enables natural growth of the bone into the hip implant.
Earlier hip replacement components were of “one-size fits all” type with limited options for variations in both shape and size. These limitations required considerable work to be done by the surgeon to make sure the patient’s bone fit the implants. Zimmer hip implants are component based which offers a great degree of flexibility in selecting implants of appropriate shape and size. The Zimmer hip systems come as 4 distinct pieces which enable the physician to select the suitable system with correct pieces to fit the hip joint. The basic design is comprised of a femoral part to connect to the thighbone, a ball joint, a neck stem, and an acetabular cup that rests in the pelvic bone. These parts together imitate the ball and socket movement of a normal hip joint.
Anatomy of the Hip
The hip joint is one of the body's largest weight-bearing joints and is the point where the thighbone (femur) and pelvis (acetabulum) join. It is a ball-and-socket joint in which the head of the femur forms the ball, and the pelvic acetabulum forms the socket. The joint surface is covered by a smooth articular cartilage that cushions and enables smooth movement of the joint.
Zimmer THA is mainly indicated for the treatment of hip arthritis. Arthritis is inflammation of the joints resulting in pain, swelling, stiffness, and limited movement. Hip arthritis is a common cause of chronic hip pain and disability. The three most common types of arthritis that affect the hip are:
- Osteoarthritis: It is characterized by progressive wearing away of the cartilage of the joint. As the protective cartilage wears down, the bone ends rub against each other and cause pain in the hip.
- Rheumatoid arthritis: This is an autoimmune disease in which the tissue lining the joint (synovium) becomes inflamed, resulting in the production of excessive joint fluid (synovial fluid). This leads to loss of cartilage causing pain and stiffness.
- Traumatic arthritis: This is a type of arthritis resulting from a hip injury or fracture. Such injuries can damage the cartilage and cause hip pain and stiffness over a period of time.
Preparation for Zimmer THA
Preoperative preparation for Zimmer THA may involve the following steps:
- A thorough examination is performed by your doctor to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could threaten the safety of the procedure.
- You will be asked if you have allergies to medications, anesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking.
- You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
- You should refrain from alcohol or tobacco at least a few days prior to the surgery.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- Arrange for someone to drive you home after surgery.
- A written consent will be obtained from you after the surgical procedure has been explained in detail.
Procedure for Zimmer THA
The surgery is usually performed under general anesthesia. During the procedure, a surgical cut is made over the hip to expose the hip joint and the femur is dislocated from the acetabulum. The surface of the socket is cleaned and the damaged or arthritic bone is removed using a reamer. The Zimmer acetabular component is inserted into the socket using screws or occasionally bone cement. A liner made of plastic, ceramic, or metal is placed inside the acetabular component. The femur or thigh bone is then prepared by removing the arthritic bone using special instruments for placement of the new Zimmer femoral component. The femoral component is then inserted to the femur either by a press fit or using bone cement. Then the Zimmer femoral head component is placed on the femoral stem. All the new parts are secured in place using special cement. The hip joint is then tested through its range of motion, and the entire joint is irrigated and cleaned with a sterile solution. The muscles and tendons around the new joint are repaired and the incision is closed.
Postoperative Care and Instructions
In general, postoperative care instructions and recovery after Zimmer THA may involve the following:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic/anesthetic reactions and monitor your vital signs as you recover.
- Most patients may need to stay in the hospital for 2 to 3 days before discharge to home.
- You may notice some pain, swelling, and discomfort in the hip area. Pain and anti-inflammatory medications are provided as needed.
- You will be placed on assistive devices such as crutches with instructions on restricted weight-bearing for a specified period of time. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
- Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
- Refrain from smoking as it can negatively affect the healing process.
- Eating a healthy diet rich in vitamin D is strongly advised to promote healing and a faster recovery.
- Refrain from strenuous activities for the first few months and lifting heavy weights for at least 6 months. Gradual increase in activities over a period of time is recommended.
- An individualized physical therapy protocol will be designed to help strengthen hip muscles and optimize hip function.
- Most patients are able to resume their normal activities in 3 to 4 weeks after surgery; however, return to sports may take at least 6 months or longer.
- Refrain from driving until you are fully fit and receive your doctor’s consent.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Benefits of Zimmer THA
Some of the benefits of Zimmer THA over traditional hip arthroplasty include:
- Minimal risk of dislocation
- Minimal implant wear
- Highly durable
- Minimal soft-tissue damage
- Improved hip stability and precision in component positioning
- Faster recovery time and minimal pain
Risks and Complications
Zimmer THA is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as the following:
- Postoperative pain
- Damage to nerves and vessels
- Thromboembolism or blood clots
- Implant dislocation (rarely)
- Leg length discrepancy
- Implant fracture