Hip Tip 9 – But please stop stretching

Considerations for prescription of Hip Flexor Stretching

1. Does your patient actually have restricted hip extension range?

It's important not to assume that someone has restricted hip extension range simply because they are not using this range during functional tasks such as gait. For those presenting with intra or extra-articular related anterior hip pain, this is usually an antalgic avoidance rather than true restriction, as we talked about in yesterday's blog.

Sure, in true 'use-it-or-lose-it ' fashion, prolonged avoidance of this range is likely to result in soft tissue shortening for most, but you can't assume. You need to assess the range of hip extension. How will you achieve an objective measure of hip extension range that you are confident is reliable and meaningful? Hip extension range is most commonly measured in a modified Thomas test position, but how do you standardise and interpret this measurement in your own clinical practice?

• Do you get the patient to hold the non-test leg to their chest?
• What happens if they can't comfortably achieve this position - particularly on the painful side?
• What do you consider to be 'normal'? ... horizontal thigh? 10 degrees of extension?
• Do you account for pelvic position and alter your expectation?
• How do you measure the range of hip extension in a reproducible manner that can be tested over time to determine effectiveness of interventions to improve hip flexor length?

The literature on this topic is very poor, most studies failing to adequately controlling pelvic position. Beneck and colleagues demonstrated that, for females, lack of stabilisation of the pelvis significantly influences the range of hip extension measured on the basis of thigh position¹.

Even if you're confident that you have i) collected a reliable and meaningful measure of hip extension and ii) it appears to be restricted, it does not naturally follow that passive stretching will be the answer.

2. Will hip flexor stretching be helpful for those with anterior hip pain ?

a. Will hip flexor stretching improve anterior hip pain?

I am not aware of any high-quality evidence that passive stretching of the hip flexors has a positive effect on anterior hip pain, but of course if you have performed or come across some great research on this topic, please feel free to let me know here.

b. Will hip flexor stretching provide meaningful and lasting improvements in hip extension range?

There are a couple of studies that have shown short-term increases in hip extension range after weeks of regular passive stretching^2,3. However, these were in painfree populations and no longer term measures were collected.

3. Will hip flexor stretching be harmful?

Maybe? A 'new cause' of direct anterior labral pathology (3 o'clock position) was suggested almost a decade ago - this was referred to as 'iliopsoas impingement' ⁴. A close relationship between the psoas tendon and the adjacent acetabular labrum was identified. Yoshio and colleagues had previously demonstrated that from 15 degrees of flexion, the psoas tendon articulates with the anterior aspect of the hip joint⁵. As the hip moves from 15 degrees of flexion into extension, we can reasonably expect the compressive load of the psoas tendon at the anterior hip to incrementally increase, thereby increasing loads on the tendon itself and the structures situated between the tendon and the head of the femur - the bursa, the capsule and the anterior labrum.

It is possible that excessive exposure to these loads over time may produce or worsen pathology in these tissues, but the research has not provided clear evidence on this one. In those who already have painful anterior pathologies of the iliopsoas tendon, bursa and underlying joint structures, passive sustained hip flexor stretching has a high risk of causing pain provocation at a minimum.