Hello, my name is Guillaume Dumont from Lexington Orthopaedics and Sports Medicine and today I'll be discussing diagnostic workup for hip injuries including the history, physical exam, imaging and the role of injections. My disclosures are available on the AOS Academy website. When I think about the hip, I really try to compartmentalize things into three areas. We have three columns here. On the left side of the column we have intra-articular issues which include femoral acetabular impingement, labral tears, capsular issues, hip instability which also includes dysplasia. In the middle column we have perichurcanteric pathologies including gluteus medius and minimus tears, churcanteric bursitis, iliotibial band, external snapping hip issues and on the right side of the column we have things like deep gluteal space, hamstring tears, core muscle injuries, basically everything else that's not packaged into the first two columns. The main driver of innovation in hip space over the last 20 years really has been femoral acetabular impingement. This has really led to a drastically increased amount of hip arthroscopy and this is what a lot of our presentations and what a lot of our physical examination maneuvers will focus on. Femoral tears often come with femoral acetabular impingement. We can see here on the left side of the video a tear of the anterior superior labrum and on the right side of the video a repair in progress. Lateral hip pathology is also very common, it can range from anything from trochanteric bursitis to partial thickness tears of the gluteus medius or minimus and even full thickness tears. If we look at the right-sided video here we see a full thickness tear of the gluteus medius and minimus. If you turn your head 90 degrees this looks very similar to a rotator cuff tear in the shoulder which is something we've learned to repair and have tools to repair with. So a lot of the techniques and tools we'll use for these procedures are very similar to those that have been used in the shoulder. All these pathologies are typically grouped together and coined as greater trochanteric pain syndrome. When we first evaluate a patient we'll take a history. It's important to understand the location of the pain, the duration of the pain, severity, whether or not there was a traumatic or sports injury or if this was something that came on over time. If there are associated mechanical symptoms such as clicking and popping and also alleviating or aggravating factors as well as treatments that patients have already attempted. Next on physical exam we'll inspect the hip for any areas of swelling or bruising. Sometimes bruising can be found over bony prominences such as the anterior superior iliac spine, the iliac crest or the greater trochanter and are common in contact sports. Sometimes the patient will come to clinic and just tell us what's going on. This is really a combination of a piece of the history and the physical exam. The patient demonstrates a hip that they feel is dislocating. We know that this is not actually a dislocating hip but the iliotibial band is snapping over the greater trochanter and this is an external snapping hip. This presents with lateral hip pain, often mechanical symptoms that are bothersome throughout the day with increased physical activity, deflection, extension, rotation of the hip. It's also important to evaluate the patient's gait. We usually don't have a gait lab at our disposal but it's important to understand some of the basic gait patterns. First of these is the coxalgic or antalgic gait which basically involves spending less time during the stance phase on the affected limb. Because it hurts the patient is trying to avoid putting pressure on this limb. Second we have the Trendelenburg gait which is seen with abductor pathology. With abductor weakness on one side, the contralateral hemipelvis will droop and then there will be a spine or lumbar lurch towards the affected side. When we're measuring range of motion during the physical exam, I like to do this in a reproducible fashion and so having the patient laying in the supine position is often the best way to do this because it stabilizes the lumbar spine and the pelvis. What we're trying to do here is measure the actual hip joint range of motion without involving the surrounding lumbar spine and pelvis motion. Next during the physical exam we'll palpate for areas of tenderness and this involves multiple areas of musculotendinous origin or insertion. At this juncture it's at least important to mention the concept of core muscle injury or what used to be called athletic pubalgia or sports hernias. This really involves pathology near the aponeurosis where the rectus abdominis and the adductor longus come together near the pubic symphysis. There are certainly other structures in the area that can contribute to this pathology but understanding the basics that are seen in this diagram really gives you a basic understanding of core muscle injury. This is something that can be seen in isolation or in combination with other pathologies including femoral acetabular impingement. Next we'll talk about strength testing. We'll grade strength of the muscles around the hip on a scale of zero to five. We can test the various muscle groups in different positions. For example we can test the hip flexors with the patient in the supine position. We can test the abductors with the patient in the lateral decubitus position and also hamstring strength with the patient in the prone position. Now we can get into various special tests for the hip. The first one we'll talk about is the log roll test. This is a very specific test for intra-articular pathology but it is not sensitive. What we're really doing when we're gently rolling the limb is seeing if there's discomfort to the anterior deep hip and what's happening is that the femoral head is gently rotating within the socket. If this causes discomfort this can be a sign of an intra-articular pathology. We have to be careful though as we're seeing young patients with FAI and labral tears that this is not always a test that shows us that there's a labral injury. This can also be positive for any intra-articular issues such as arthritis, avascular necrosis, even patients with different pathologies like dysplasia can have pain with the log roll test. Next is the stinch field test. This is really a resisted straight leg raise that's performed at approximately 30 degrees. Groin pain can indicate intra-articular pathology however we have to be careful because anterior pain with the stinch field test can also represent hip flexor pain or musculotendinous pain. Next we'll talk about the so-called impingement test. Basically this involves placing the hip in a position of flexion, adduction, and internal rotation. The name impingement test is somewhat of a misnomer because the test can reproduce pain with a lot of different pathologies that involve the hip joint not just with femoral acetabular impingement. Sometimes it can be helpful to also compare this to the contralateral side. When we're performing the impingement test and some of these other special tests what we're really trying to identify is this structural pathology. We have pincer morphology here seen on the acetabular rim adjacent to the labrum which is compressing the labrum and causing pain with certain motions. On the flip side of the joint here, we see a cam morphology on the left side. This is a large cam, and then on the right side, we see where this has been decompressed to reduce the impinging bone. Moving on with special tests, this is the posterior impingement test. I would say that this is less commonly performed but sometimes can be thought of when we're concerned for a posterior labral tear or posterior instability. Basically we are placing the hip in the opposite of what the typical impingement test is. So instead of flexion, adduction, internal rotation, we're placing the hip in a position of extension, abduction, and external rotation. Sometimes this can also elicit pain with adhesive capsulitis or again posterior labral tears. The Faber maneuver is often used. This test can be positive with a variety of different pathologies. Usually it's painful with anything affecting the ipsilateral intra-articular area of the hip and also with the contralateral SI pain. We often see patients that comment on lateral pain when performing this test as well. Really what's important here is when we're documenting this test, I wouldn't say something like positive Faber maneuver or positive Faber test. I would say where the patient is having the pain when we're performing this maneuver as this can be much more informative. Next we'll touch on the basics of hip imaging. Our basic modalities include x-ray, MRI, and sometimes CT. Looking at x-ray, this is the initial diagnostic modality and we can really identify the presence or the severity of a lot of different pathologies before even getting any more advanced imaging. MRI we use more for the evaluation of the labrum, cartilage injury, and also some musculotendinous pathologies and injuries around the hip. I prefer a non-arthrogram 3 Tesla MRI. In the past people were using arthrograms much more, however with the advent of much clearer MRIs I don't think this is usually necessary. Next we'll talk about CT. Really this is used to define the specific, very precise structural anatomy around the hip. This can be useful for preoperative planning and also can give us a good look at different rotational torsional pathologies of the femur. The AP pelvis is the workhorse of hip imaging. It often provides the most clinically relevant information so it's really important to get a good AP pelvis that's as well centered. So how do we know if our AP pelvis is well centered? Well we're looking for approximately 2 to 3 centimeters between the coccyx and pubic symphysis. This avoids a more inlet or outlet view and of course symmetric obturator foramen and symmetric hemipelvis. If we have this we know that the measurements we're going to make on the hip can be relied upon. When we look for arthritis in the hip preservation world we use the tonus scale. So really we're trying to usually treat patients with low amounts of arthritis or no amounts of arthritis. These include usually a grade 0 on the tonus scale and sometimes grade 1. Grade 0 involves really no signs of arthritis. Grade 1 involves some sclerosis of the joint with minimal joint space narrowing and maybe some mild osteophyte formation. Grade 2 involves moderate joint space narrowing, small cysts in the femoral head or the acetabulum. Grade 3 changes show advanced arthritis with joint space obliteration, large acetabulum, femoral head cysts and severe femoral head deformity. These are patients that we're not usually dealing with in the hip preservation world. These are sent to our arthroplasty partners. Next we'll look at different measurements around the hip as they pertain to femoral acetabular impingement and hip dysplasia. First we'll look at the lateral center edge angle. This is measured on the AP pelvis. We'll draw a best fit circle on the femoral head and then a line from the middle of the femoral head directly superiorly. Another line that goes to the edge of the acetabular source seal. The angle between these two lines is the lateral center edge angle. This is a measure of acetabular coverage of the femoral head. Normal is typically been defined above 25 degrees and below 40 degrees although typically if you're approaching 40 degrees this can often represent some pincer morphology. There is a category of acetabular dysplasia or under coverage of the acetabulum that's been described as borderline acetabular dysplasia and this is usually between 20 to 25 degrees or sometimes some authors will describe this as 18 to 25 degrees. What's important to remember here is that the acetabular morphology is not a two-dimensional issue. This is a three-dimensional structure and so we can't simply use the lateral center edge angle to define hip dysplasia or FAI. We have to use other angles and other views to look at this as well. On the DUN 45 degree lateral view we can examine the CAM morphology. What we're going to do here is measure the alpha angle. So this is a measure of the asphericity of the femoral head neck junction. The alpha angle is originally described for use on the axial MRI views however commonly we use it in the clinic on your lateral view of choice which for me is the DUN 45 degree lateral. It can also be used on the frog leg lateral. So we draw a perfect circle on the femoral head. We identify the center of that circle and draw a line from the middle of the femoral head down the axis of the femoral neck and another line that subtends basically to where the bone exits that circle. The angle between these two is the alpha angle. The higher the angle the larger the CAM morphology. I also obtain a false profile on all new patients in the clinic. The false profile can give us a good look at the anterior joint space and can also give us an idea of the anterior acetabular coverage. So just like we measured the lateral center edge angle we can measure the anterior center edge angle. We also see the morphology of the anterior inferior iliac spine. So sometimes the anterior inferior iliac spine seen here can contribute to hip impingement. We can see here in the arthroscopic video that this is being decompressed. We see the capsule superiorly, the labrum inferiorly, and the bone that we're seeing between that is the anterior inferior iliac spine. We'll then look at MRI. So we use MRI to look for labral injuries, cartilage injuries, and also any other musculotendinous injuries around the hip. So here we're looking at the labrum. We'll see basically fluid extending between the acetabular rim and the labrum. On the left, we have a coronal view, and on the right, we have a sagittal view. We can also see some slight bony edema of the acetabulum on the sagittal view here, which can indicate more aggressive chondral injury and subchondral injury of the bone. Sometimes cartilage injuries are very difficult to identify on MRI, whereas we may see the labral tear quite well. Delamination of the cartilage may not be visible. This is best seen with arthroscopy here. Ideally, we can identify these issues before surgery, but sometimes we can be surprised when we find a labral tear to also have fairly substantial cartilage damage associated with this. Imaging for lateral hip pain or greater trochanteric pain involves the same modalities. On x-ray, sometimes we can see enthesophytes or bony irregularities, sclerosis at the greater trochanter, and on MRI, we'll see fluid around the greater trochanter and sometimes full thickness or partial thickness tears of the gluteus medius or minimus. When we see edema around the gluteus medius and minimus insertions, this isn't always trochanteric bursitis. Previously, these patients were all diagnosed with trochanteric bursitis, and they had injections for years and years and years, but now we know that the tendon can sometimes be more of what's causing the pain, and treating this like a rotator cuff injury, whether it's a full thickness injury or partial thickness injury, can help get your patients better. Proximal hamstring injuries can cause pain at the ischium. These can be atraumatic or traumatic. We can identify these on MRI. So on the left, we have a coronal view, which is showing us edema and partial thickness tear of the hamstring origin at the ischium, and in here, we have a sagittal view of the same hamstring showing the same findings, from a different perspective on the right side. MRI can also identify other pathologies, such as ischiofemoral impingement. Here, we're looking at the ischiofemoral space, where we see the quadratus femoris between the ischium and the lesser trochanter of the femur, and there's edema in this muscle group, which can identify ischiofemoral impingement. CT is often used for preoperative planning for femoroacetabular impingement. Here, we see a 3D rotation of the acetabulum on the left and the femoral head on the right. We can use these to really understand the morphology of the hip that we're going to be treating surgically. Also, with CT, we can identify rotational pathologies to determine whether femoral torsion is involved in the patient's issue. With all the different issues that can cause pain around the hip, image-guided diagnostic injections have really become a helpful component of the evaluation of hip injuries. The ultrasound has really helped with this. Intraarticular injections can now be performed using ultrasound guidance. Peritracheal injections directed adjacent to the gluteus medius and minimus tendons can be done. Image-guided injections for ischiofemoral impingement are also very helpful. The last thing we want to do is operate on the wrong part of the hip, or treat or target the wrong part of the hip, and so these tests can really hone in on what the true problem is for the patient and give them their appropriate treatment. In summary, the hip is a complex joint with a variety of structures that can be injured or cause pain. Common things are common, so really be on the lookout for hip arthritis, femoral isthoidal impingement, labral tears, greater trichotillary pain syndromes. However, consider alternate sources of pain, including extraarticular pathology that can sometimes sneak up on us, but really be valuable things to identify for our patients. What we're trying to do here is solve a complex problem What we're trying to do here is solve a complex puzzle using our patient history, physical examination, imaging, and diagnostic injections so that we can really choose the right solutions for our patients. Good luck with it. Please contact me if I can help you in any way.

hip injuries

diagnostic workup

femoral acetabular impingement

imaging techniques

diagnostic injections