Midlands Orthopaedics & Neurosurgery

Hip Arthroscopy

In hip arthroscopy, the inside of a joint is examined with an arthroscope, which is a flexible, fiber-optic tube with a tiny camera that is attached to a monitor. This lets an orthopedic doctor see your joint up close to help diagnose and treat some forms of joint pain. Arthroscopic surgical equipment is also used in some types of minimally invasive joint surgeries to help get a more in-depth view.

What is Hip Arthroscopy?

Hip arthroscopy, which is sometimes called a “hip scope,” is a minimally invasive procedure in which an orthopedic surgeon uses an arthroscope to look inside the hip joint. This procedure lets the doctor figure out what’s causing your hip pain or other joint problems.

Arthroscopy can also be used to treat some hip problems, and in these cases, the surgeon makes one or two additional small incisions to make room for arthroscopic needles, scalpels, or other special surgical tools that are used during arthroscopic hip surgery.

Benefits of Hip Arthroscopy

A hip arthroscopy carries many advantages over traditional hip surgery, which include but are not limited to:

Very little stress or trauma to the joint
Minimized hip pain and scarring
Generally done on an outpatient basis, which means patients return home after the procedure
Typically has a short recovery period
May slow down the progression of hip arthritis by treating its cause early on
Can delay or eliminate the need for a hip replacement by treating conditions that cause osteoarthritis of the hip as soon as possible

Common Conditions Hip Arthroscopy Can Treat

Here are some of the most common hip injuries and conditions that can be treated with a hip arthroscopy procedure:

Hip impingement, which limits the range of motion and is a major cause of osteoarthritis
Labral tear, which is when a specialized cartilage called the labrum lining the hip socket is torn, can be repaired or trimmed
The removal of:
- Loose fragments of cartilage inside the joint, which are usually caused by an injury, such as a torn labrum
- The diseased or inflamed joint lining
- Painful bone spurs

Who is a Good Candidate for Hip Arthroscopy?

Most of the time, hip arthroscopy is suggested for younger people with hip pain who don’t need a hip replacement. Most of the time, their hip pain is caused by a sports injury, an overuse injury, or abnormalities in the shape of the bones that make up the hip joint. Your doctor might suggest arthroscopy to fix damage to the soft tissues in your hip or to change how the bones in your hip fit together.

Types of Hip Replacement

Total hip replacement is an operation designed to replace the damaged joint. All types of hip replacement are based on the principle that a section of bone must be removed from the end of each bone (femoral head and acetabulum) and replaced by an artificial piece that is well-fixed to the bone on both sides of the joint.

Implants fixed solidly to both bones rub against each other when the hip moves, preventing the bone ends from being irritated. Many types of total hip replacements are currently utilized and can be classified in several different ways.

There are many brands available in each category and there are hundreds of factors (e.g., type of metal, the shape of the implant, sterilization method, tools for insertion, etc.) that must be considered when choosing the appropriate implant in each case.

The physicians and physical therapy department at Midlands Orthopaedics & Neurosurgery will ensure the most comprehensive approach to help find relief for you in the quickest way possible.

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Types of Fixation To Bone

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Cement Fixation

In 1962, Sir John Charnley used a small (22mm) stainless steel ball on a long stem which was inserted into the bone to replace the femoral (ball) side of the joint and a high-density plastic socket to replace the acetabular (socket) side. Both of these components were secured to the bone with a self-curing acrylic polymer commonly referred to as bone cement (methyl methacrylate).

Several generations of designs have evolved from this original Charnley prosthesis. The ball is now modular thereby allowing balls of different sizes, materials, and neck lengths to be placed onto the stem. Most balls are now made of either a cobalt chrome metal alloy or a ceramic material. Stems are now made of either cobalt chrome or titanium. The socket component is usually titanium with a bone ingrowth porous surface and an exchangeable bearing liner. The liner can be made of polyethylene (plastic), cobalt-chrome (metal), or ceramic. Sockets fixed with cement have largely been abandoned in the US. Cement fixation of the stem is now used in less than 10% of hip replacements, usually in older weaker bones.

Bone Ingrowth Fixation

We are now in an era with the widespread use of devices that are designed to attach to bone without the use of cement. Bone will attach to a metal implant if the surface of the metal has a rough or porous surface. This process is called bone ingrowth or osseointegration. The bone must be prepared precisely for these devices. For successful bone ingrowth to occur the implant must achieve an initial stable press-fit when implanted and the porous coating must sit right up against live bone. In general, these devices are larger, longer, and stiffer than those used with cement but are proportional to the size of the individual bone. Surface coatings, such as hydroxyapatite, are also being utilized to hasten and/or enhance bone fixation. Many different devices using cementless fixation have been utilized since their introduction in the U.S. in 1977. It is now generally accepted that these implants remain fixed to bone longer than cemented devices. The theoretical downside is the occasional failure of bone ingrowth, but this is a very rare problem, except possibly for very old weak bones. There is one other problem with these implants. In 2-5% of patients’ activity, related thigh pain may develop. Even with well-fixed implants, they can be painful due to the stiffer modulus of these implants. There is no solution to this problem.

Hybrid Fixation

Hybrid fixation is when one component is inserted without cement, usually the socket, and one component is inserted with cement, usually the stem.

Bearing Surfaces

All artificial bearings create wear debris, just as the rubber wears off your tire going down the road. This wear debris is deposited in your body. If the load is small, you can usually tolerate it well for many years. Our goal is to use implants that generate the least quantity of wear debris as well as the type of debris that results in the least tissue reaction. The original Charnley bearing was a stainless steel ball against plastic (polyethylene). This is no longer used. Modern alternative bearings have about 100X lower wear rates than the older cobalt chrome against standard polyethylene bearings.

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Metal on Plastic

Metal on plastic is the most commonly used combination. Plastic wear debris is deposited around the hip joint and may travel along lymph channels. But it does not leave the body. In young active people with standard plastic (polyethylene, SPE) liners, enough plastic debris is released to cause severe bone destruction in 30% of patients within 8 years of implantation. Newer cross-linked linear polyethylene (XLPE) has dramatically lowered this problem in small early studies out to 10 years. When ceramic balls are used against the plastic, wear debris seems to be further reduced.

Smaller bearing diameters produce less wear but result in a higher risk of dislocation. Larger bearings were not possible with SPE for this reason. Because XLPE has better wear properties, larger heads are now being used. Although XLPE wears better, it is often more brittle. As the bearing size increases, the liner thickness decreases. More brittle XLPE may therefore be more subject to breakage rather than wear. Also, larger heads have recently been associated with trunion (where the head is attached to the stem) corrosion. Therefore, there is much disagreement about ideal bearing size because of competing problems: wear/breakage vs. instability.

Ceramic on Plastic

Ceramic on plastic has similar characteristics as above but probably cuts the wear rate in half.

For the standard 28mm bearing size dislocation risk is about 5% within 1 year, while it drops to 1% for 36mm bearings. By 10 years follow-up dislocation risk nearly doubles. About half of dislocations are recurrent and require revision surgery. The most common reason for revision hip surgery is instability.

Ceramic on Ceramic

Ceramic on ceramic bearing produces the least quantity and best-tolerated wear debris of all bearings. Ceramic surfaces are brittle and can fracture, especially with impact activity. This is now exceedingly rare (less than 1:10,000). When these implants are placed in nonideal positions, they may exhibit a stripe wear pattern and emit a loud squeak that can be heard across the room. This can be very unpleasant and require revision surgery. This occurs in 1-2 % of cases, but can probably be resolved by better implant positioning and larger ceramic bearings.

The main problem with ceramic bearings is their size. The same instability problems exist with the standard 28mm bearing size. Larger sizes are now in use with a new stronger ceramic called Biolox. This will reduce the dislocation rate but will require thinner ceramic socket liners. Time will tell if these will be equally fractured resistant as the thicker alumina ceramic liner that has 10-year data.

Metal on Metal

Metal-on-metal bearings made of cobalt chrome were first used in the U.S. when joint replacement began in the late 1960s. The component design and fixation techniques were primitive by today’s standards. Further, the bearing manufacture was inconsistent and these devices were discontinued in the 1970s. Now with modern technology, bearing surfaces can be made optimally smooth and round, and thus the wear is minimized.

We have learned that for optimal function, there needs to be less than 5 um residual roughness and a polar bearing arrangement with a 50-100 um radial clearance. Cobalt chrome is the only metal that works. Trace amounts of molybdenum and Nickel are present in this alloy. There is still controversy about ideal metallurgy (cast vs. forged, high vs. low carbon content, heat treated or not) but the most commonly used is cast, high carbon non-heat-treated. M/M devices were reintroduced in Europe in 1988. There are now U.S. manufacturers as well as European firms manufacturing all-metal bearings. The reaction of our body against excess metal debris results in more soft tissue inflammation while plastic causes more bone destruction (osteolysis).

Metal bearings are so strong that very thin (4mm) socket components can safely be built without any risk of fracture. Also, a bone ingrowth layer can be directly attached to this implant. Thin, strong, one-piece sockets allow reconstruction of the hip joint with a natural bearing size, virtually eliminating hip instability, the most common complication of this surgery. In combination with similar thin femoral components, hip resurfacing is made possible.

Despite laboratory studies showing minimal wear, high wear states resulting in metallosis (excess metal in the tissues) have now been reported in patients. The incidence of this adverse wear failure (AWF) problem varies, it has been a cause of failure in 1% of cases for 10 years. The revision for AWF is no more difficult than revision for other failure modes. We have now learned the proper acetabular component positions to completely avoid this problem. It turns out that the problem is caused primarily by two factors, socket components that are designed very shallow and steep socket component inclination positions. The combination of these problems results in edge wear releasing excess metal debris.

Ceramic on Metal

Ceramic on metal has shown slightly lower metal wear in laboratory studies, but this has not been confirmed in clinical studies.

How Much Bone/Joint is Replaced

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Stemmed Total Hip Replacement

Stemmed total hip replacement is by far the most commonly used. John Charnley was the first to make this a routinely successful operation in the 1960s. Numerous modifications have occurred since his time. Several millimeters of bone are removed from inside the socket and a metal implant with a porous ingrowth surface is tightly implanted into the prepared bone bed. A bearing liner is then locked into place in the implanted metal shell. This leaves a much smaller cavity for the ball.

Therefore the head and neck of the femur must be amputated. A stem is then fixed into the hollowed marrow canal of the top of the femoral shaft using either cement or bone ingrowth technique. A smaller (than natural) ball is then attached to the trunion of the stem (morse cone taper junction). This ball fits into the smaller socket liner.

Hip Surface Replacement

Hip surface replacement accomplishes the same basic goal as Total Hip Replacement (THR) with much less bone removal and preservation of normal biomechanics. Bearing size and femoral offsets remain the same for the normal femur. This was tried in the 1950s by Charnley with Teflon implants, by others with primitive metal-on-metal bearings, and in the 70s with metal-on-plastic bearings. Finally, Derek McMinn applied modern metal-on-metal bearings to resurfacing in the 1990s. Mainly because the femoral head is preserved, it is much more difficult for the surgeon to get adequate access to accurately place the deeper socket component.

In stemmed THR, the head and neck are amputated early in the operation allowing much easier access to the deeply placed socket. This technical difficulty is the primary reason why many hip surgeons are reluctant to perform this operation. It has been demonstrated in numerous scientific papers that the complication rate is much higher when surgeons are learning this operation. This learning curve extends for several hundred cases. Difficulty in placing the socket component accurately is one of the major contributing factors to recent problems with adverse wear failure.

Hemi-Surface Replacement for Osteonecrosis

One option to minimize wear debris and tissue reaction is to eliminate the artificial bearing by replacing only the diseased part of the joint. A hemi-surface replacement was sometimes recommended in the past for patients who had osteonecrosis of the femoral head (also referred to as avascular necrosis) and had intact remaining articular cartilage on the acetabulum or pelvic side.

The hemi-surface replacement preserves and maintains bone by providing physiological stress transfer to the femoral neck and proximal femur. It avoids inflammatory reactions and loosening due to any artificial bearing wear debris. However, if only one-half of the joint is replaced, the degree of pain relief is not as good as if both sides of the joint are replaced. It is not always possible to convert this to total hip resurfacing. I do not advise the use of this operation.

Are you experiencing hip pain and discomfort?

Contact us to schedule an appointment to speak with one of our orthopedic doctors at one of our locations near you or give us a call at (803) 256-4107.

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Recovery from Hip Arthroscopy

Symptoms usually get better right away after the procedure, but some pain can come back as the irritated joint lining heals. Some movements may also make the hips and knees sore for a short time.

The swelling should go down in about a week, and stitches are usually taken out between seven and ten days after the surgery. Depending on the treatment you had during your procedure, your full recovery time may be different from others.

Patients who undergo hip arthroscopy usually are required to use crutches for the first two weeks after the procedure and do six weeks of physical therapy. Depending on what was done during their surgery, it may take anywhere from 3 to 6 months before patients experience no pain after physical activity.

Multimodal Pain Management Program

Adequate pain management is essential to allow rapid recovery of patients after joint replacement surgery. With modern protocols, most patients have minimal pain postoperatively and can progress rapidly with learning their rehab program. They can be discharged from the hospital within one to two days after the surgery and can now even have outpatient surgery without a hospital stay.

It is best to minimize hospital time to avoid complications. A stay in the rehab unit after hospital discharge is unnecessary, except for selective elderly or severely debilitated patients who have no family support at home for one to two weeks. Even privately hiring a home health aide is preferable. Rehab/hospital stays expose patients to additional risks in my opinion.

A multi-modal pain management system decreases narcotic requirements and results in less pain with fewer side effects. Significant pain postoperatively is now generally only experienced by a small percentage of patients with a low pain tolerance or by patients that are already habituated or addicted to prescription narcotics before surgery.

There is a safety limit to narcotics that can be administered postoperatively. With the following multimodal pain management program, we can usually eliminate most pain postoperatively without reaching this limit.

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