Understanding the Hip

Understanding the Hip

This page is a primer on hip anatomy, the most common ways the hip gets injured, and the procedures Dr. Wolff uses to address them. If you’d rather read it as a PDF, you can download the complete Surgery Instructions PDF.

Hip Anatomy and Labral Tears

To simplify things, think of the hip as a ball that fits into a socket. The hip labrum is a rubbery protective ring that sits on the rim of the socket (acetabulum) of your hip joint. The labrum’s role is to hold the top of your femur securely within your hip socket, decrease pressure on your articular cartilage, and provide stability.

A labral tear is defined by the detachment of the labrum from the rim of the socket. These usually are not acute injuries — rather, damage to the labrum accrues gradually with time. This depends on the anatomy of your bones, but also on the surrounding musculature and your activity level. Tears can vary in severity, but this often does not correlate directly with severity of symptoms. In fact, many people have labral tears for which they compensate for years before becoming symptomatic–or in fact, never become symptomatic. While MRI imaging is important, we do not rely solely on images to determine a treatment plan, as this is often a multifactorial problem.

Prior to recommending surgery, it is important for us to ensure that the hip is indeed the root cause of your symptoms. We factor in your level of pain and function and weigh those against your goals to formulate a plan that best serves your needs.

Symptoms of a labral tear are variable but typically involve a deep pain in the hip, oftentimes in the front of the hip or groin area. The pain can move around the hip (front, back, side, etc.) and is often accompanied by some degree of muscle soreness, tenderness around the hip, and sometimes some loss of motion. More often than not, symptoms just show up one day and are not brought on by a specific trauma. The vast majority of the time, there is a shape or an orientation to the bones of the femur (the ball), the acetabulum (the socket), or both, that puts the labrum at risk of a tear. Far and away, the most common problem is femoroacetabular impingement (see also labral tear posts on our blog).

Femoroacetabular Impingement (FAI)

There are two types of FAI: CAM-type, which describes an irregular shape of the femur (ball), and Pincer-type, which describes over-coverage of the acetabulum (socket). While CAM is the more common type, these two types can — and often do — co-exist.

CAM-type FAI

In CAM-type FAI, the ball isn’t perfectly round. When it tries to fit into a round socket, there is a shearing force on the rim of the socket. The labrum, sitting at the rim of the socket, can get repetitively displaced over time, often along with delamination (shearing off) of the adjacent articular cartilage. We worry about the articular cartilage in the hip because this is what keeps the bone of the ball from rubbing on the bone of the socket. When we lose this, we call this osteoarthritis. With too much loss of cartilage (arthritis), hip arthroscopy will not be effective and the surgical options are limited to hip replacement. Because CAM-type FAI is the most common reason for osteoarthritis, this is something we would prefer to correct (when symptoms warrant) to decrease your risk of arthritis developing over time. Our multicenter research has shown that acetabular cartilage damage at the time of surgery predicts poorer outcomes, which is why correcting the underlying mechanics matters before the cartilage breaks down.

Pincer-type FAI

In Pincer-type FAI, the socket is too deep, either in one area or more globally. This brings the rim of the socket into closer contact with the neck of the femur and puts the labrum in a position where it can get crushed and cause pain.

Mixed Type

Many patients have both CAM and Pincer features. The treatment plan addresses whichever components are contributing to symptoms.

Surgical Intervention

Many people with labral tears compensate for them well (possibly including you, prior to when your hip started bothering you). In most cases Dr. Wolff would recommend trying to compensate via non-surgical means first. Surgery is not usually recommended unless it has become clear that non-surgical means are unlikely to achieve your goals.

Most Common Procedures

Arthroscopic Labral Treatment

If Dr. Wolff encounters a labral tear at the time of surgery, there are two treatment options: Repair or Reconstruction. There are many studies showing great benefit, both biomechanically and functionally, to having a well-functioning, healthy labrum. We don’t always know based solely on imaging which technique will be used at the time of surgery, though most of Dr. Wolff’s cases are labral reconstructions. The reason is that if you think of FAI and the resultant labral tear as a gradual process of breakdown over time, simply putting a damaged labrum back where it started does not address the damage to the tissue itself that has accrued over time. It also doesn’t address the often insufficient tissue that remains after removing damaged and painful sections.

Labral Repair

If the labral tissue is still of good quality but is simply detached from the bone, Dr. Wolff may choose to repair it back to the bone. This is done with plastic suture anchors that go into the bone and have sutures attached, which are passed through and/or around the labrum. When these sutures are tied, they hold the labrum to the bone where it heals.

These sutures and the anchors aren’t absorbable but don’t need to be removed because they don’t cause problems unless they are misplaced at the time of surgery.

Dr. Wolff will typically only employ the repair technique in younger patients with little damage and sufficient good labral tissue. With more time, more damage has typically accrued and the remaining tissue is of poor quality, which may put you at risk of needing another surgery to reconstruct the labrum.

Labral Reconstruction

Labral reconstruction is performed when there is insufficient healthy labral tissue to repair. Because patients do better with a well-functioning labrum and have a high failure rate when segments are missing or non-functional, the labrum is taken out and replaced with a donated fascia lata allograft crafted and sized to serve as a new labrum.

This also eliminates damaged tissue (which can be a significant pain generator) and replaces it with healthy tissue that your body will incorporate over time. If you had a labral reconstruction, don’t see this as a failure — it’s a means to reduce your risk of failure in the future. We want you to get better with the least amount of intervention possible.

In Dr. Wolff’s published research — including a 5-year follow-up study showing both labral repair and complete reconstruction offer durable, promising results and a separate primary circumferential reconstruction series — labral reconstructions in his hands fare just as well, if not better, than repair patients — despite often having to overcome larger challenges (worse labral damage, previous failed surgery, longer duration of symptoms, etc.).

You can also watch Dr. Wolff’s video talks on labral reconstruction technique on the Presentations page (including the Labral Reconstruction Toolkit and ICL: Reconstruction).

Don’t lose sleep over the use of donated tissue (allografts). These have been used with excellent success and safety profiles for many uses over many years all over the body. The donated tissue does not have antigens on the surface like a donated organ would, so your body does not recognize it as foreign and cannot “reject” it in that way.

Cam (Femoral) Osteoplasty

The osteoplasty of the femur (cam osteoplasty) is the contouring/shaving of the femur bone to make the ball round so the labrum won’t continue to tear and the articular cartilage won’t continue to break down. If it has been determined you have a cam lesion, this will always be corrected at the time of surgery. We use advanced computer navigation software intra-operatively to help ensure that it is corrected in its entirety. Restoring as close to normal mechanics as possible gives you the best chance of a well-functioning hip for the short-, medium-, and long-term.

Pincer (Acetabular) Osteoplasty

The contouring of the acetabular (socket) bone to an ideal depth so as to continue to provide structural stability while positioning the labrum in the most functional position. Dr. Wolff’s earlier published work on rim resection and the center-edge angle (Philippon, Wolff et al., 2009) helped establish how much bone to remove to balance impingement relief against preserving socket stability.

Synovectomy

The synovium is the layer of cells that line the capsule of the joint and produce joint-lubricating fluid. When the synovium gets inflamed, it can be quite painful. A synovectomy is performed by cauterizing the inflamed synovial cells. After the mechanics of the hip have been corrected, when the synovial cells regrow, they will do so in a normal fashion (i.e. not inflamed).

Chondroplasty

The process of smoothing irregular and loose edges of articular cartilage. This is only employed if there is some early damage to the articular cartilage.

Osteochondral Allograft

When larger areas of cartilage are missing, we will use a donor osteochondral allograft to restore the articular cartilage (with a very thin layer of bone) to the area in which it has been lost. This has been quite effective and durable in situations where the damage is confined to a limited region of the hip. For a deeper dive, watch Dr. Wolff’s narrated “ProChondrix: Cartilage Restoration in the Hip” presentation.

Ligamentum Teres Reconstruction

The ligamentum teres is a ligament that runs between the ball and the socket deep in the hip. In some people, it likely plays little role in the overall stability and functioning of their hip, while in others it likely plays a crucial role. This is more common in patients with hypermobility disorders (e.g. Ehlers-Danlos syndrome) and/or evidence of hip instability.

To reconstruct this ligament, a donor tissue graft is placed through the neck and head of the femur and across to the acetabulum and fixed on both ends in an analogous way to how ACL reconstructions are performed in the knee. For more on managing hypermobile and unstable hips, see Dr. Wolff’s narrated “Hypermobile Athlete Cases” presentation. For a plain-language overview of the “loose hip” problem, read his blog post on hip microinstability. Multicenter outcomes data on ligamentum teres treatment alongside labral work was reported in our 2021 OJSM study (Bodendorfer, Wolff et al.).

Frequently Asked Questions

Is this type of surgery performed preventatively? No. It is not a surgery that should be performed unless you are experiencing symptoms caused by the labral tear or femoroacetabular impingement (FAI). It is not recommended that it be performed based solely on an abnormal imaging result.

How many labral repairs has Dr. Wolff performed? Dr. Wolff performs approximately 250 arthroscopic hip surgeries per year. He has been in practice since 2008.

How many labral reconstructions has Dr. Wolff performed? Over 2,000. He performed his first in 2009 and is considered a pioneer in this field. He has among the largest series of labral reconstructions performed in the world.

He has shown his technique to be equally or more effective than labral repair.

What type of allograft is used for the reconstruction? A part of a donated iliotibial band/fascia lata is custom sized and shaped to reconstruct the patient’s labrum.

If too much arthritis is found during surgery, will Dr. Wolff perform a total hip replacement instead? No. Dr. Wolff will not perform a total hip replacement if too much arthritis is found. Finding too much arthritis in surgery is something that Dr. Wolff tries to prevent, which is why so many imaging studies are carried out before surgery including x-rays, high-quality MRIs, CT scans, etc.

What is Dr. Wolff’s success rate for this surgery? Over 90% in general, with durable results out to at least 5 years in our published outcomes, but in reality it is rare for people to have trouble down the road if they have navigated their surgical recovery without problems. There are, however, factors including arthritis, dysplasia, and patient non-compliance that may lower this number. All patients are individuals who heal at their own pace. Factors such as patient health, age, and post-operative demands all play a role. Dr. Wolff will do his best to provide you with an honest appraisal of your odds of success of the various treatment options.

Further Reading and Resources

Selected related publications (for the full labral reconstruction series, see the citation list above):

• Rehabilitation following Arthroscopic Surgery of the Hip — Clinics in Sports Medicine, 2016
• Acetabular Cartilage Lesions Predict Inferior Outcomes for Labral Repair and FAI Treatment — Arthroscopy, 2022
• Arthroscopic Treatment of Borderline Dysplasia with Acetabular Retroversion — American Journal of Sports Medicine, 2021
• Concomitant Labral Repair and Ligamentum Teres Debridement vs. Isolated Labral Repair — OJSM, 2021

For the full list, see Dr. Wolff’s research page.

Video presentations from professional meetings: Dr. Wolff’s presentations page includes narrated talks on labral reconstruction technique, the Labral Reconstruction Toolkit, borderline dysplasia, ProChondrix cartilage restoration, hypermobile athlete cases, and how to approach failed hip arthroscopy.

Next Steps

If you’re preparing for hip arthroscopy, the Preparing for Hip Arthroscopy page covers the practical side — scheduling, what to bring, work and school leave, medications, and physical therapy.

If you’ve already had surgery, the Post-Op Instructions page covers recovery, medications, and discharge instructions in detail.