ARS: Acetabular Rim Syndromes. Hip Pain.
Some examples of MOI’s (Mechanism of Injury)
-An athlete complains of a gradual onset of pain deep within his or her anterior groin.
-Forceful kicking a ball with the medial border of the foot may cause a sharp pain with a catching sensation.
-A case involving a ballerina with 10 months of left hip pain originated during a high kick in the abducted position; she felt a sudden catching sensation in the anterior left groin.
-A car accident with knee dashboard impact forcing femur posteriorly.
-A wrestler in a quadruped position forced back onto heels (buttock to heels)
Labral lesions have a strong correlation with
anterior inguinal pain
giving way of the hip
Pain may be reproduced with flexion and internal rotation of the hip
An audible click may also be present
The patient history usually does not reveal significant trauma
The onset of pain may be related to sports and may involve a mild twisting or slipping injury
Radiographs in patients with labral tears are typically unremarkable.
If early osteoarthritic disease is present, the pain is out of proportion to the radiographic changes.
While the pain is usually in the groin, it could also be in the trochanteric and buttock region. A significant trauma is not necessary to disrupt the labrum – twisting or falling may be causative. The injury is usually caused by the hip joint being stressed in rotation. The pain could be acute or insidious. The most common complaint is discrete episodes of sharp pain precipitated by pivoting or twisting. Clicking or catching is common but not always present. Activities that involve forced adduction of the hip joint in association with rotation in either direction tend to aggravate. The majority of labral tears (up to two-thirds) are located anteriorly.
Their hip pain is often nonspecific regarding symptoms.
Radiological findings may be negative.
It is important to rule out early any possibility of fractures, infections, inflammation or ischemic necrosis; laboratory tests of blood, urine and at times synovial fluid may be necessary.
Acetabular dysplasia, considered pre-osteoarthritic by some, is a valid clinical entity that must be considered. Some references are calling this disorder dysplastic acetabular rim syndrome (DARS).
Early symptoms will occur due to overload of the acetabular rim caused by hip motions such as a combination of flexion, adduction and internal rotation.
Getting out of a car or doing the breast stroke are examples of this type of movement stress.
Snapping, locking and clicking are common in ARS, causing the clinician to think of problems related to the labrum or a painless snapping iliopsoas.
Snapping hip complaints must be discriminated from functional hip problems such as anterior femoral glide syndrome and IT Band syndrome.
Symptoms due to hip instability may be related to ARS.
The patient may suffer unexplained falls or the feeling that his or her hip may give way.
With acetabular dysplasia, there may be excessive anteversion of the femoral neck, causing an increase in hip internal rotation on examination. The capsular pattern of the hip that indicates osteoarthritis is almost always a decrease in hip internal rotation. Therefore, as soon as osteoarthritis appears, decreased hip internal rotation will also appear.
We are going to leave things here for today…….we wanted to leave you with 3 words for the day……..INTERNAL HIP ROTATION. Keep these 3 words in your clinical hat for the day, look for its loss and start thinking about your runners, your patients. Look for this loss when the patient is supine and in the straight leg position. Test the hip rotation from spinning the hip (from an ankle contact point) into internal rotation, compare side to side.
More tomorrow ……but remember, sometimes it is not the part……but the anchor for the part….. hence why we will be talking about the lower abdominals as the week goes on. The amount of Internal hip rotation available is only as much as the abdominal wall can support or anchor (ie. a weak abdominal wall cannot support much functional internal hip rotation…….. why ? tune in tomorrow ! as we bring this full circle.)
……….. we are more than…….Just The Gait Guys
We have much to say on this topic. A few years ago I was doing some lectures on Hip Rim syndromes (ARS: Acetabular Rim Syndromes) for an imaging center and realized the lack of clinical knowledge on the topic. Recently, we have been receiving some referrals and emails regarding and we figured it was time to “hit the hip” topic for awhile.
Here is an article to start with. It has some basic info. If you want to be able to follow our progression of Rim Syndromes and labral issues and how to approach them clinically etc start here (and, if you are an athlete with hip issues, there will be understandable and usable info for you as well as the week progresses). We have some nice powerpoint presentations on this stuff too, we are looking for a way to make them available for you as well.
**** Here is our main problem with the article, as admitted by the authors……… “
** “Clinical Relevance: Although this study does not include muscular forces across the hip joint, it does provide a clue as to the stresses about the labrum through the complete range of motions of the hip, which may help in providing a better understanding of the cause of labral tears and in the protection of labral repairs.”
from The Gait Guys……..”this is the problem with this study, and studies like it, particularly cadaver studies. There is no way to accurately assess the muscular forces and function at the joint. We have taken many hip labral tear and Rim syndrome patients and resolved their pain by looking at the muscular dysfunction that is leading to the Rim syndrome, impingement, tears etc…….. remember, an MRI is a static photo in a non-weightbearing state without muscular engagement. A rather useless test for this problem if you ask us. The information from the MRI’s regarding tissue pathology in the syndrome is nice and helpful, but you still have to fix the issues that allowed the problem to begin in the first place ! Repairing and debriding the labrum does not necessarily, and often does not, resolve the causative issues. Understanding normal gait and the implications of pathological gait patterns is paramount to fixing these issues. The tissue pathology is the tissue pathology, you still have to fix the problem that started the whole process ! ” …..The Gait Guys___________________________________________________________________________________
Am J Sports Med. 2011 Jul;39 Suppl:92S-102S.
Strains across the acetabular labrum during hip motion: a cadaveric model.
“Background: Labral tears commonly cause disabling intra-articular hip pain and are commonly treated with hip arthroscopy. However, the function and role of the labrum are still unclear. Hypotheses: (1) Flexion, adduction, and internal rotation (a position clinically defined as the position for physical examination known as the impingement test) places greatest circumferential strain on the anterolateral labrum and posterior labrum; (2) extension with external rotation (a position clinically utilized during physical examination to assess for posterior impingement and for anterior instability) places significant circumferential strains on the anterior labrum; (3) abduction with external rotation during neutral flexion-extension (the position the extremity rests in when a patient lies supine) places the greatest load on the lateral labrum.Results: The posterior labrum had the greatest circumferential strains identified; the peak was in the flexed position, in adduction or neutral abduction-adduction. The greatest strains anteriorly were in flexion with adduction. The greatest strains anterolaterally were in full extension. External rotation had greater strains than neutral rotation and internal rotation. The greatest strains laterally were at 90° of flexion with abduction, and external or neutral rotation. In the impingement position, the anterolateral strain increased the most, while the posterior labrum showed decreased strain (greatest magnitude of strain change). When the hip is externally rotated and in neutral flexion-extension or fully extended, the posterior labrum has significantly increased strain, while the anterolateral labrum strain is decreased. Conclusion: These are the first comprehensive strain data (of circumferential strain) analyzing the whole hip labrum. For the intact labrum, the greatest strain change was at the posterior acetabulum, whereas clinically, acetabular labral tears occur most frequently anterolaterally or anteriorly. The results are consistent with the impingement test as an assessment of anterolateral acetabular labral stress. The hyperextension-rotation test, often used clinically to assess anterior hip instability and posterior impingement, did not show a change in strain anteriorly, but did reveal an increase in strain posteriorly. Clinical Relevance: Although this study does not include muscular forces across the hip joint, it does provide a clue as to the stresses about the labrum through the complete range of motions of the hip, which may help in providing a better understanding of the cause of labral tears and in the protection of labral repairs.”
Shawn and Ivo, ……… The Gait Nerds