Why stairs show up a sore hipEmerging evidence
Stairs are a one-leg task done over and over. In 4 people with hip implants that measure the load, the force through the joint was 251% of body weight going up and 260% going down, against 238% walking, with about 23% more twisting going up; in 10 people the stairs were about 16% to 19% above walking. So the joint itself carries only a little more on stairs.
The muscles do much more. Going up bends the hip further and works the buttock muscles harder than going down, and the muscles on the outside of the hip hold the pelvis level over the standing leg. These are lab studies of people with implants or without pain: they explain why stairs show up a sore hip early. No study shows that stairs wear the hip out.
Sources 1, 2, 3, 4, 5
The outer hip tendons: the commonest stair pattern from mid-lifeStrong evidence
Pain on the bony point at the side of the hip usually comes from the gluteal tendons, often called hip bursitis or greater trochanteric pain syndrome. In 2,954 US adults aged 50 to 79 at high risk of knee arthritis, 17.6% had it (about 1 in 6), with more than three times the odds in women; it went with low back pain and knee arthritis. NHS inform says it is commonest in women aged 40 to 60 and names "climbing stairs", lying on that side, crossing the legs and standing on that leg ("hanging on the hip") among its triggers.
On the way up, people with this pain let the hip drift towards the midline and lean the trunk away, the position that squeezes those tendons. In 65 people, pain within 30 seconds of standing on the sore leg was a strong clue to the diagnosis, and no tenderness over the bony point made it unlikely. These are small studies.
Sources 6, 7, 8, 9, 10, 11, 12
The hip joint: arthritis from mid-life, impingement when youngerStrong evidence
From about 45, a deep ache in the groin, the front of the thigh or the buttock, worse with activity and stiff for under 30 minutes in the morning, is usually hip arthritis, which the National Institute for Health and Care Excellence (NICE) diagnoses from symptoms. NHS inform lists "going up/down stairs" among the hard jobs, and Arthritis UK says "Pain when you bend your hip going up or down the stairs ... is often a sign of a hip problem".
In younger active adults, a sharp groin pinch with deep bending, low seats or getting into a car points to hip impingement or the rim of the socket. In 51 clinic patients, 83% had groin pain and 65% were worse sitting; stairs were a lesser trigger, though 39% used a banister.
Sources 13, 14, 15, 16, 17
The back, the front of the hip, pregnancy and the rarer causesEmerging evidence
NHS inform says hip pain can come from the back even when the back doesn't hurt, often as "pins and needles, sharp, hot or burning pain" in the leg. Hip joint pain itself can spread: in 51 people whose pain was proven to come from the joint, it was felt in the buttock (71%), thigh (57%), groin (55%) and below the knee (22%). A limp, groin pain or a hip that turns in less made a hip cause more likely than the spine.
After a hip replacement, the iliopsoas tendon at the front can rub, worse lifting the knee and on stairs: it followed 3.3% of 1,602 replacements. In pregnancy, pelvic girdle pain affects up to 1 in 5 women and is worse on stairs and standing on one leg.
Rare but important: a stress fracture of the hip bone in runners, walkers and recruits, which needs an urgent X-ray and often an MRI (magnetic resonance imaging) scan; a broken hip after a fall in later life; infection; and in children, the hip's growth plate. No study counts how often each cause is behind stair pain in the general public.
Sources 18, 19, 20, 21, 22, 23, 24, 25, 26, 27
Going up, coming down, or stairs but not walkingEmerging evidence
No study says whether going up or coming down hurts more for any cause. Going up bends the hip more and works the buttock muscles harder; coming down puts slightly more force through the joint and asks the muscles to control the lowering. So pain going up, standing on one leg and getting dressed fits the outer hip tendons or the joint, while pain mostly going down is more often the knee, though the hip can hurt both ways (our reading).
Stairs hurting "but not walking" is a common early pattern for the same reasons: more bend, more single-leg control and a little more force (our reading).
Sources 3, 2, 10, 28
What a scan shows, and what it doesn'tStrong evidence
NICE diagnoses hip arthritis at 45 and over without imaging, and X-ray change and pain often disagree: only 9% to 16% of frequently painful hips showed arthritis on an X-ray, and about 1 in 5 hips with X-ray arthritis were frequently painful. Outer hip pain is diagnosed by examination, and an NHS trust says scans "are not required for confirmation".
Scans find things that don't hurt. Gluteal tendon changes showed on MRI in half of hips without outer hip pain; only 20% of 877 people with outer hip pain had bursitis on ultrasound; impingement shapes and labral tears are common in hips that don't hurt. A scan matters when it changes the plan: an urgent X-ray, then MRI if it's normal, for a suspected stress fracture; MRI for suspected early avascular necrosis or before hip surgery; ultrasound or MRI for a suspected gluteal tendon tear.
Sources 13, 29, 9, 30, 31, 32, 33, 27, 26
How it usually goesEmerging evidence
Outer hip pain often takes months. In the LEAP trial, 29% of the wait-and-see group had succeeded by 8 weeks and 52% by a year; in Dutch general practice, 36% still had pain at a year; NHS inform says "6 to 12 months of rehabilitation" is common.
Hip arthritis varies: over 2 years, 31% of 222 people had stable mild pain while others went up and down or worsened, and X-ray severity didn't predict the 5-year course. In the NHS trials of impingement, people improved with physiotherapy as well as with surgery. No one can promise a date.
Sources 34, 35, 7, 36, 37, 38
