Table 2. Core painful sensations expressed by the participants.

Name of pain	Main characteristic	Additional characteristics	Participants’ words
Background pain	Always there, located everywhere in the body	May be akin to long-lasting tiredness	“It envelops your body, it’s like a cloud of pain, not strong but worrying, nagging, like a mosquito buzzing around”
	Sort of oozing pain, with a dull pitch and a variable intensity	May start low and then become more present/ stronger, acute
“Deep pain”	Inner location: close to or within the “bone”	Precise impact point hard to identify	“Deep inside the body, not on the surface. It’s hard to know where it starts”
	Dull to acute	Feelings of “alien things inside” = augmented anxiety	“Like an alien moving in your body”; “a slow moving lava flow”
“Stabbing pain”	Short, intense, brutally penetrating pain, with a slow, gradual withdrawal of pain	May happen at night. May stop as rapidly as it started. Tearing feeling / bodily integrity. threatened. Patient may stop moving/doing what he was doing with the “shock” of the pain. Sometimes cries, shouts. “Defective limb” feeling. Mostly in hands, knees.	“Violent, occasional but regular. It doesn’t last long, only a few seconds. Deep. It will go away slowly, gradually”. “It can take up to one hour to ebb away”. “Pain stronger than anything else, 8/10”. “At the base of your thumb”. “In the knee when I turn my leg in a certain way. I’ve stopped going at the pictures because after 2 hours when you have to stand up, it’s awful”
	May happen several times per day
“Tearing pain”	Close to a stabbing pain but closer to the skin / with larger impact. Intense, acute pain; Lasts longer since it awakens the “background pain”	If very intense, feeling that “the heart will stop beating”. Anxiety provoked by intensity of pain. Seizes all of the body + awareness of patient. May happen at night	“Like tearing something, you can’t trust your muscles anymore, as if I had bones only.” “I already stayed trapped by it 3 hours long in my bathtub because I couldn’t get up. Going on my knees is impossible to bear”. “ I already fainted from it”
“Electrical shock”	Sudden, extremely acute, but less intense than the preceding pain.	No identifiable cause. Brief and goes away quickly, entirely. Global physical reaction to it. Some report a “vibrating” sensation. No regularity/pattern in occurrences.	“Like touching a jellyfish”. “Intensity: 9/10, but doesn’t last”. “When it happens, I brutally stand up in the bus”; “you start up”. “Happens even if I’m not doing anything”. “Sometimes it happens 3 times in a short laps of time, sometimes nothing for some months”.
	Less anxiety because no feeling of physically penetrating/tearing alien element.
“Contact pain”	The merest touch awakens a fierce pain. Very common (most patients)	Very intense pain: “unbearable” that stops all movement (patient will drop what he/she was holding). Added tearing sensation.	“You break a lot of plates that way”; “I will cry if I have to press a sponge”; “If I have to go on my knees - it’s as if I was kneeling on broken glass, it’s impossible, appalling. Las month I had to at my doctor’s, I shouted from the pain of it”. “This pain is 10/10”
“Missing limb”	More discomfort + acute anxiety than real pain (not always a “pain”). Patient has the feeling his/her leg is suddenly missing or unable to carry him/her and is afraid of falling / really hurting himself/herself if on stairs, or outside, etc.	For some: violent pain (when caused by a movement?). Dull, pain when no particular movement involved. Deep pain. Feeling of unhinged limb. Arrested move. Loss of equilibrium.	“Sometimes my leg will give way and I fall, so I have to be careful in the stairs”. “It’s abrupt, fast”. “It is a stress because you feel less assured. It’s a deep pain”. “You distrust you own body”. “Your knee feels like a sponge and the joint is not working anymore so you do not trust it and do not dare to put your weight on it”.
“Cramp” (feels like) or wooden leg syndrome	(limb) Stiff under the touch + feeling of inner / outer tension.	A finger or a limb. Nearly crushing sensation (but not physical). Night or day; no identifiable cause. Dull pain; very large impact zone	“As if the nerve was very tight and stretched to the maximum”. “A dull pain all along my leg, like a wooden leg”. “In the fingers, it is strange: they are stiff, with a contracted look”
“Pulsating knee”	Dull pain – can be acute; burning “inside”, swelling around the knee	Warm to the touch. Pulsating pain + feeling prickling. Skin “too tight”, stiff. Red skin. Long: up to one day	“I can feel my heart beating in my knee”. “Impossible to bend my knee. It’s twice as large as it was; warm to the touch, and painful. My skin is red too. Intense burning sensation, but it never lasts more than one day”
“Brutal paralysis”	A “violent” pain, not lasting + limb/finger “blocked” + sensation of inner ravaging	May be noisy (cracking). Feeling of “inner ravaging”. Less frightening on knees. High level of anxiety when there is a feeling of ravaging/entropy inside.	“Violent, but doesn’t last; fingers are contracted, you can’t put them down flat; it feels as if the cartilage is crumbling away, as if it were gravel inside”. “My husband hears it when it cracks, my grandchildren hear it when I am on the stairs”.