Single leg standing considerations for gluteal tendinopathy

Hi all,

Welcome to tendinopathy blog 27.

Looking forward to the new case study based Mastering Lower Limb Tendinopathy Course – kicking off with Melbourne in 2 weeks for which there are a couple spots. Still space available at this stage for ADELAIDE, BRISBANE AND PERTH.

The tendon research is coming out thick and fast again, more good stuff next week, I promise! Side tracked this week by teaching my son (and myself) how to skateboard. Non-linear pedagogy in action! Waiting for the moment that it clicks @erikMeira

Blog number 27 (subscribe here) focuses on 1 cool study looking at weightshift and standing kinematics in gluteal tendinopathy. As I have said before, single leg standing appears simple but it can be an art form! Some really important clinical messages about what to consider in assessing and rehabbing single leg standing in this patient group.

Single leg standing considerations in gluteal tendinopathy

Background: Another great study in gluteal tendinopathy by Kim Allison with Vicenzino, Bennell, Grimaldi, Hodges and Wrigley (what a team!). A previous study (Bird et al. 2001) has reported an ‘abnormal’ pelvic position among gluteal tendinopathy patients during single leg stance, and this is often a clinical observation, but it has not previously been quantified. These authors investigated trunk, pelvis and hip kinematics in a gluteal tendinopathy and control group during weight shift and single leg standing. They also investigated whether hip abductor strength influenced single leg stance kinematics.

What they did: They recruited 20 participants with gluteal tendinopathy (GT) and 20 age matched controls. Gluteal tendinopathy diagnosis was based on the presence of lateral hip pain without groin pain for >3 months, pain on palpation of the greater trochanter and glut tendon tests eg lateral hip pain on single leg stance pain and FADBER test. They were excluded if they had radiological evidence of hip OA or other injuries that could affect balance/gait. They measured hip abductor strength in supine using a fixed hand held dynamometer (see photo below). The tested limb was in mid range rotation and 10 degrees of hip abduction. They used the maximum force output from the three trials and it was converted to torque (torque = force x moment arm). Participants were instructed to lift one leg to 45 degrees of hip flexion and maintain 1 leg standing for 8 seconds. Lower limb 3D motion data was recorded during this task.

Pelvic lateral shift was represented by the horizontal distance between the calcaneum and a vertical line descending from the midpoint between the ASIS markers – see schematic below which clearly shows that that distance is much smaller if they shift their pelvis laterally. They expressed this distance as a percentage of half the distance between the ASIS’s to account for differences in pelvic width/base of support.

What they found: Key differences between the groups were…

• GT group had a higher BMI and inter ASIS/trochanteric distances
• GT group feet were 14% closer during bipedal stance
• GT moved into greater hip adduction and lateral pelvic shift during weightshift
• GT group had greater hip adduction and less contralateral pelvic rise in SL stance
• GT group were 42% weaker in isometric hip abduction testing
• Hip abductor weakness may partly explain hip adduction in SL stance as this difference disappeared when controlling for hip abductor weakness
• When controlling for group differences in BMI and ASIS/trochanteric widths hip adduction differences in weighshift and foot position in bipedal stance were no longer there
• Adjusting for pain did not change any of the kinematic differences identified

Clinical interpretation: a key finding is that when the GT patients stand on 1 leg they had greater hip adduction which seemed to be related to their hip abductor strength. The authors suggest that they may do this because - a) more hip abduction force can be generated in greater hip adduction, so they tend to go there, OR b) they have a shifted length tension (are weaker in inner range) because they habitual spend time in lengthened positions (outer range, ie adduction). Clinical take home is; assess hip abductor function in different ranges of hip adduction and work on inner range hip abductor function if necessary.

The GT group also had a lower pelvic hike than the control group in single leg stance – ie they both tended to elevate the pelvis in single leg stance but the GT group did these less than the control group. The authors suggest that the lack of pelvic drop or Trendelenberg may be related to the fact that the opposite leg was at 45 degrees hip flexion which may influence/facilitate a contralateral pelvic hike, which makes sense.

During weightshift, the GT group tended to adduct their hip more, and go into more lateral pelvic shift. The hip adduction was partly explained by the fact the GT group had a larger BMI and wider pelvis, so probably tried to get their centre of mass more over their weightbearing leg. The lateral shift did not disappear however when controlling for BMI and pelvic size or even hip abductor strength, or pain. Maybe strength may be related if measured in standing or in inner range? (again highlighting that our clinical strength measurements needs to be thorough ie different ranges, endurance, weightbearing, etc). Or maybe this weightshift pattern is a learned motor pattern secondary to pain. Regardless, definitely something to consider identifying and addressing in managing GT patients.

One of the points the authors pick up on is whether small differences in pelvic angles can be detected by clinicians. For example, the mean difference in pelvic drop was 2.9 degrees and hip adduction 4.7 degrees, both tricky to detect with visual observation alone. Hip adduction angles were correlated with the foot position under the pelvis measure, so the authors suggest that maybe this measure of pelvic lateral shift may be useful clinically to indicate pelvic shift/hip adduction.

Would have been lovely to see a measure of anterior sway – ie pelvis forward shift in relation to the foot, as well as muscle activation around the hip eg gluteal, TFL, etc.

So overall, single leg standing seems simple, but it can be challenging and is a key rehab transition for a GT patient. Fun to rehab as different cues and strategies work for different people. This is a great study highlighting some key clinical considerations.

All the best until next time

Peter