I hope the last two posts discussing the differential diagnosis of hip & groin pain have been useful, as I know this is quite a complex area & one that I have found useful to revise. I have been trawling through references once more to supplement the information gleaned from James' (Moore) course & the books in my library that have contributed most on this third instalment have been DeStefano's "Greenman's Principles of Manual Medicine" & Kapandji's "The Physiology of the Joints, Volume 2: The Lower Limb".
So now, the final group of influencing factors contributing to hip & groin pain relate to pathology in the hip joint itself. Falvey et al (2009) argue that pain localising to the lateral aspect of the “groin triangle” (demarcated by the ASIS, pubic tubercle & 3G point), stems from the femoro-acetabular joint.
Pathologies of femoro-acetabular joint can present as pain (often much more diffuse & generalised than adductor pain), mechanical symptoms or a reduced range of movement.
It is worth noting that hip pathology, whether degenerative, inflammatory or infective in nature, will refer to an average of 6.4 pain sites but groin referral is always present. Mechanical symptoms may include catching & painful clicking, rather akin to a meniscal injury in the knee. Any reduction in range of movement at the joint may be the result of a bony block caused by a loose body/impingement or through the protective muscle guarding activity of the iliopsoas or quadratus lumborum (Philippon & Schenker, 2005).
Hip joint pathology can be subdivided into those affecting the joint space, those affecting the chondral surface & those affecting the labrum.
Joint space related pathology includes cysts, foreign bodies (such as chondral loose bodies), synovitis or a rupture of the ligamentum teres, which Gray & Villar (1997) classified into Type I (complete), Type II (partial) & Type III (degenerative).
Bardakos & Villar (2009) report that ligamentum teres ruptures are difficult to diagnose, as there is no test that specifically assesses the integrity of the ligament. A history of twisting, falling on a flexed knee or hyper-abduction should be cause for suspicion, whilst pain radiating into the groin & down to mid-thigh may be accompanied by locking, clicking or giving way. Meanwhile clinical assessment may highlight a reduced range of movement into extension or flexion/internal rotation & the log-roll, resisted SLR & McCarthy’s Tests should all form part of an examination.
Arthroscopy remains the gold standard for detecting ruptures, with MR arthrogram being the favoured means of MR imaging but with a low reliability rate of only 9% in some studies.
Chondral surface related pathology includes both osteochondral lesions/flaps & defects.
Pathology affecting the labrum rarely presents in association with a history of trauma & labral damage is often the victim caused by the shape of the joint, which exerts its influence through repetitive joint stress in flexion & internal rotation. Pain will be reported over the anterior thigh region & can be accompanied by a clicking or catching sensation, which are aggravated by actions taking the joint into flexion & rotation. In the Western population, the anterior labrum is more commonly torn, whereas the Eastern population shows a greater frequency of posterior labral tears, which has been linked to the different toileting positions of each.
In cases of femoro-acetabular impingement (FAI), the rim of the acetabulum repeatedly conflicts against the proximal femur causing lesions of the labrum or even the acetabular cartilage. Lavigne et al (2004) classified impingements into 4 categories: i) Normal ii) Cam iii) Pincer iv) Mixed, according to the mechanism of the abrasion.
James describes three tests that can be used to established whether the impingement is affecting the anterior (FADIRs – flexion, adduction, internal rotation), posterior (Fitzgerald’s – flexion, abduction, external rotation & then actively scoop into extension) or superior (FABIRS – flexion, abduction, internal rotation & then scoop round the superior acetabulum) part of the labrum.
Another condition that affects the integrity of acetabulum, is hip dysplasia, which describes the condition where the femoral head & acetabulum are malaligned. Either the femoral head or neck is malformed (aspherical, has a protuberance or has been subject to torsion) or the acetabulum is either too shallow or too extensive. If the relationship between the femoral head & the acetabulum is sub-optimal, chronic labral traction or compression will give rise to a degeneration of the articular cartilage & over time a sub-chondral cyst may be formed. This will lead to premature osteoarthritis.
Reliable assessment of hip dysplasia can be performed using a plain film x-ray & establishing the Centre-edge Angle of Wiberg, first described by Wiberg in 1939. The centre edge angle is the angle between the vertical & the outer edge of the acetabular roof, with the centre of the femoral head as the axis.
Wiberg suggested that a centre edge angle of greater than 25 degrees would be considered normal, whilst an angle of less than 25 degrees would suggest instability at the joint & a centre edge angle of less than 15 degrees will indicate that degeneration may occur. Generally an angle of less than 20 degrees would be indicative of severe dysplasia.
Other tests that should be conducted as part of an examination of the adult hip include:
- Craig’s test, which looks at the degree of anteversion (>15 degrees) or retroversion (<10 degrees) of the femoral neck & is conducted in prone
- Hip rotation, conducted in supine with the hip & knee at 90 degrees
- Prone hip rotation, which if conducted concurrently tests the integrity of the pubic femoral & ischiofemoral ligaments
- Hip extension, which, James (Moore) assesses by lying the subject in prone, then using the examiner’s body weight to block rotation of the innominate & cupping under the knee – a great technique to establish full hip extension but one that might not be appropriate on certain patients of a non-athletic nature!!
- Prone FABERS, which if positive will indicate an inflamed joint & if a PA pressure is applied at the end of range will either confirm a synovitis (if the impingement test was clear) or may further indicate a labral tear (if the impingement test was positive).
So that is a 3 part review of hip & groin assessment, although I would add that there are other considerations that must be added when looking at the adolescent athlete, which I will touch on in another post. However, now it is time for me to bid farewell to Lee Valley Athletics Centre for Easter & get back up home to Edinburgh...back on the road again!!!
