Hip joint popping/instability during pike/deadlift

[startinglilium]

Hi everyone,
some background:

A couple of years ago, during a Jefferson Curl, I felt the femur heads of both hips slightly sub dislocating.
It felt as the heads were forced toward the front. (see image)
I stopped Jefferson curls and after a while, the discomfort went away.

A year ago, I went through a period of intense stretching of the legs, using Stretching & Flexibility, especially the Hamstrings and Hip flexors (with partner variations).
One night, before going to sleep, I did a relaxed pike in the bed, and again my hips sub-dislocated, exiting a little out of the sockets and going back.

I stopped stretching and after a while, the discomfort went away.
During the convalescence, the hips were loudly popping every time I made a Deadlift move (same kind of sound of when you crack your knuckles, with no pain, but with a distinct feeling of movement in the joint and a bit of discomfort).
Even when picking up something from the floor, on the ascendent phase, at around 90° of flexion of the femur in the hip, there was the popping.

A week ago I had a popping with light pain, during a proper deadlift. A 85% of 1RM weight. I was fatigued as it was the 5th set, and I was coming from an intense period of gym, with allergy during the night, hence less than ideal recovery.

I would like to understand the mechanics of this, could it be a Hip Flexors weakness? Any test I can do to narrow down the cause?

• if I do a standing pike with feet apart, shoulder width or more, no popping
• if I do a standing pike with feet pointing out (externally rotating the hip), no popping
• if I do a pike with knee in maximal extension (actually hyperextension, for me), no popping, it only happens when the knee are flexed a little, as in a deadlift.
• When I try to pike, it feels like the Hamstrings are pulling forward the head of the femur, kind of causing a joint distraction.
• The discomfort, slight pain I feel, is in the front region of the hip capsule.
• If, during the ascent of the deadlift, I consciously contract the glutei, the popping is greatly reduced or eliminated
• I tried light foam rolling of the area below the iliac crest, where the quads attach, the tensor FL, and immediately afterward, the pain/popping was greatly reduced or eliminated.

I made a sketch showing the direction I feel the head of the femur going.

Any thought/suggestion is greatly appreciated.
Femur Head subdislocating.jpg

[Mark Rippetoe]

Starting Strength: Basic Barbell Training | The Aasgaard Company

[porcopedico]

A hip usually doesn't dislocate without major forces.either fascia lata or psoas tendon snaps

[startinglilium]

Mark, thanks for your reply, I've read the book.
Maybe could you point where in the deadlift section there is something specific that can help me?

[Mark Rippetoe]

I would suggest that your perception of dislocation is incorrect, as perceptions often are. If "pikes" are a problem, stop doing them and get your squat and deadlift up.