Joint, Ligament and Muscle Disorders

Hip Resurfacing

Anatomy

The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is formed by the femoral head, which is the upper end of the thighbone, or femur. In a healthy hip, the surfaces of both the ball and socket are covered with articular cartilage, a smooth tissue that cushions the ends of the bones, allowing the femoral head and acetabulum to glide painlessly against each other during movement.

Description

During hip resurfacing, unlike total hip replacement, the femoral head (ball) is not removed. Instead, it is left in place, where it is trimmed and capped with a smooth metal covering. In both procedures, however, the damaged bone and cartilage within the acetabulum (socket) is removed and replaced with a metal shell.

Candidates for Hip Resurfacing

If you have more advanced osteoarthritis, have exhausted nonsurgical treatment options, and your hip is significantly interfering with normal activities and affecting your quality of life, your orthopaedic surgeon may recommend this surgery. Unlike hip replacement, hip resurfacing is not suitable for all patients. Generally, the best candidates are younger than 60, larger-framed males, with strong, healthy bone. Patients that are older, female, smaller-framed, or with weaker or damaged bone are at higher risk of complications, such as femoral neck fracture or reaction to metal ions. A comprehensive evaluation by your orthopaedic surgeon will help determine if you are a good candidate for hip resurfacing.

Advantages

• Easier to revise—Implants used in both hip replacements and hip resurfacings are mechanical parts, and they can, and do, wear out or loosen over time—usually 10 to 20 years after the procedure, although this timeframe can vary dramatically depending on the patient. If an implant fails and an additional operation is necessary, the second procedure, called a revision, can be more complicated than the initial operation. Because hip resurfacing removes less bone from the femur than traditional hip replacement, many surgeons believe replacing a failed implant is easier after hip resurfacing.
• Decreased risk of hip dislocation—In hip resurfacing, the size of the ball is larger than in traditional hip replacement, and closer in size to the natural ball of your hip, making it potentially harder to dislocate. However, this advantage is dependent on surgical approach and the type and size of implants used.
• Range of motion—Hip resurfacing patients are usually able to move their hips in a greater range of motion than total hip patients, and may have a subtly more natural walking pattern.

Disadvantages

• Femoral neck fracture—A small percentage of hip resurfacing patients eventually break the thighbone at the femoral neck, usually making it necessary to convert the hip resurfacing into a hip replacement. With a hip replacement, there is no risk of this fracture because the femoral neck is removed, however, fractures around the implants can still occur.
• Metal ions—In a resurfaced hip, the metal ball moving within the metal socket can, over time, produce tiny metal particles called ions. Patients developing sensitivity or allergy to these ions may experience pain and swelling. Although unproven, there is also the concern that ions may increase the risk of cancer. Hip replacements that also consist of a metal ball and metal socket share the same potential risk. This potential complication seems to be more common in women and is now limiting this procedure to younger males.
• Difficulty—Hip resurfacings are more difficult than total hip replacements for surgeons to perform, and usually require a larger incision.

Surgery

After admission into the hospital, you will be evaluated by a member of the anesthesia team. The most common types of anesthesia are general anesthesia (you are put to sleep) or spinal, epidural, or regional nerve block anesthesia (you are awake but your body is numb from the waist down). The anesthesia team, with your input, will determine the best option for you. Your surgeon will see you before the surgery and sign your hip to verify the surgical site.

A hip resurfacing operation typically lasts between 1 1/2 and 3 hours. During surgery, your surgeon will make an incision in your hip and upper thigh in order to reach the hip joint. The femoral head is then dislocated out of the socket and trimmed with specially designed power instruments before being cemented with a metal cap. The cartilage that lines the socket will be removed and a metal cup will be pushed into the socket and held in place by friction between the bone and metal. Once this cup is in place, the femoral head will be relocated back into the socket and the incision will be closed.

Following surgery, you will be moved to the recovery room where your recovery from the anesthesia will be monitored for several hours. Once you are awake, you will be taken to your hospital room. You can expect to be in the hospital for a few days. You will feel some pain after surgery, but your surgeon and nurses will provide medication to make you as comfortable as possible. Pain management is an important part of your recovery because feeling less pain will allow you to start moving and get your strength back more quickly.

Recovery

Depending on your surgeon's recommendation and the strength of your bone, you may be able to begin putting weight on your leg immediately after surgery. A walker, cane or crutches may be needed for a few days or weeks until you become comfortable enough to walk without assistance. In most cases, patients return home from 1 to 2 days following surgery. Your doctor will discuss with you what precautions can be taken to avoid problems and complications after surgery, and your physical therapist will help you with specific exercises to strengthen your hip and restore movement for walking and other normal daily activities. You will continue to see your orthopaedic surgeon for follow-up visits at regular intervals and will most likely resume your regular daily activities approximately 6 weeks after surgery.

Your new hip may activate metal detectors required for security in airports and some buildings. Tell the security agent about your hip replacement if the alarm is activated.

Complications

As with any surgical procedure, there are risks involved with hip resurfacing. Your orthopaedic surgeon will discuss these with you and take specific measures to help avoid potential problems. Although rare, the most common complications of hip resurfacing include: infection; blood clots in leg veins or pelvis; femoral neck fracture; dislocation; loosening and wear of implant; nerve and blood vessel injury; bleeding; risks of anesthesia; and in a small number of patients, pain continues or new pain occurs following surgery. Occurring even less frequently are major medical complications, such as heart attack or stroke. Chronic illnesses may increase the potential for complications. Although uncommon, these complications can prolong or limit full recovery. Your surgeon will prescribe antibiotics prior to surgery to prevent infection and blood thinners after surgery to prevent blod clots.