Femoral acetabular impingement (FAI) – Overview, examination, and treatment ideas
Following my teams journal club where we discussed FAI I thought I would reflect and share my understanding and knowledge around this topic.
What is it?
FAI ‘occurs when there is a limited joint clearance between the femoral head-neck and the acetabular rim’ . There are several factors that can lead to FAI:
Structural changes of the hip structures such as:
Acetabulum (pincer deformity, osteophyte formation)
Femur (cam deformity, articular cartilage changes, osteophyte formation)
Labral ( tear (the labrum has free and sensory nerve endings making its superficial layer a player in proprioception and nociception))
Motor control imbalances
TFL dominant hip flexion (+/- weakness in iliopsoas) leading to increased internal rotation during hip flexion
Reduced posterior glide in the joint (posterior capsule tightness can be secondary to tightness in anterior musculature such as iliopsoas and/or weakness+/- tightness in posterior musculature such as the glute muscle group/hamstring)
Excessive anterior or posterior pelvic tilt altering the interaction angle of acetabulum and femur
Playing sports that are more prone to increased hip flexion positions e.g. running, ballet, hockey.
It is important to note that studies have shown that positive findings for pathology on MRI scans do not always correlate to pain and a diagnosis of FAI, as highlighted in the Warrick (2016) agreement, requires positive clinical findings, a positive finding on imaging and appropriate symptoms.
The vertical ground reaction forces (VGRF) estimations around the hip are as follows:
· 1.15 x BW female and 1.23 x BW male during walking
· 2.36 X BW F and 2.45 M x BW during jogging
Therefore, good control and strength around the hip are vital for successful performance.
Once ruling out any sinister or serious signs and other pathology then a combination of the below may be present:
Pain that starts in the anterior groin, which over time can spread to posterior joint and anterior thigh – lack of groin pain helps rule FAI out
‘C’ sign/location of pain
Pain that is sharp or dull +/-a mechanical click/giving way at the hip
Aggravated by activities involving hip flexion +/- internal rotation and adduction: prolonged sitting, Squatting, sudden change of direction in sport, incline running etc.
Once other causes of hip pain (stress fracture, OA, bursitis, GTPS etc) have been ruled out then FAI assessment can begin. A combination of the following may be seen:
Reduced hip flexion, internal rotation and adduction
Reduced posterior joint play in an AP glide
Tightness of iliopsoas/TFL/rectus femoris in a Thomas test
Tightness of TFL in modified Obers’
Tightness of hamstrings in a SLR
A click in the groin when lowering leg from hip flexion
Weakness in strength testing of the following: iliopsoas, glute med/min, glute max, hamstrings and TFL
Positive findings in movement analysis (such as internal rotation at the hip, adduction at the hip, a lateral pelvic shift, avoidance of weightbearing) such as the step down, single leg stance, single leg squat, forward bend, gait assessment etc.
Posterior chain assessment – hamstrings firing before glutes can cause an anterior glide at the joint
Treatment will depend on what was found during the assessment and should be tailored to the individual and their goal. The below are ideas of some techniques/tools I use but it is not an exhaustive list, nor is it a ‘recipe’.
Avoidance of aggravating positions/regular position changes
Lifestyle changes – change in activity that may be prone to FAI (e.g. reduced a running session a week to swim instead etc.)
Prognosis- Worsening symptoms without intervention, reduced return to sport rates following surgical interventions, likelihood of OA development in cam/pincer morphology.
For runners: Increase in cadence can reduce VGRF on hip. Reducing terminal hip extension can also relieve pressure on anterior structures.
Address strength deficits (start in open chain and work towards closed chain. Consider lumbopelvic control/dissociation whilst performing)
Hip flexors – SLR in ER to reduce TFL activity, seated MOS maintaining neutral LSP, Resisted MOS with band/cable, isometric hip flexion in seated or lying, activation of iliopsoas in seated/crook lying.
Glute med/min – Side lying hip abduction, clam, wall push, crab walking, single leg lateral step, calf raises maintaining neutral pelvis.
Glute max – Bridge (single or double legged), hip thrusts, prone hip extension, single leg squats, step ups.
Hamstrings – heel slide, prone knee bends, standing knee flexion, raised bridge, RDL (single or double legged), gymball prone tantrums
Length deficits (Think to address muscle weakness first to prevent tightness/stiffness and then compliment with mobility programme):
Physio performed muscle energy techniques (MET), pressure point release, passive stretching.
Hip flexors – Thomas test, self MET in supine, lunge with pelvic tilt, heel to bottom with pelvic tilt
Glutes – hip flexion and adduction in supine, supine/standing heel to opposite knee/hip ER with hip flexion past 90 degrees,
Hamstrings – Self MET, toe touches, supine knee extension/hip flexion
Motor control deficits
Lumbopelvic control: 4 point kneeling arm and hand reach, Plank with hip extension, plank with hip abduction, Side plank with leg lift, standing MOS with maintain single leg stance, knee bends in plank with gym ball
Proprioception: ‘Around the world’, bosu squat, 4 point kneeling knee slides, controlled articular rotations (CARs) in 4 point kneeling or standing
Altered joint play
Physio performed AP mobilisations in crook lying (Useful in increased hip flexor activity/ posterior capsule tightness/ reduced posterior glide)
Physio performed PA mobilisations in prone (useful in increased posterior pelvic tilt/ reduced LSP lordosis)
Self lateral glides with hip flexion
Physio performed lateral glides with belt into flexion
Physio performed caudad glides +/- IR and ER in hip flexion
It is not within the scope of this blog to go into detail regarding non-operative vs operative management. Evidence has demonstrated similar outcomes with both but highlighted the increased likelihood of developing OA with FAI. As a general rule of thumb I would progress with rehabilitation for at least 3 months (given there are no disabling/quality of life concerns), to allow for soft tissue adaptations, without a significant improvement prior to referring onwards for orthopeadic opinion.
Disclaimer: This blog is aimed more towards healthcare professionals, there is no ‘one recipe’ as everyone presents differently and always seek professional opinion if you are experiencing problems.
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