It really depends on how your body reacts to wearing them. Walking mechanics can vary greatly from person-to-person.
On average, your natural foot position is in a few degrees of “plantar-flexion”, meaning that a slightly raised heel in a shoe’s foot-bed would be the most supportive and natural for walking. Most walking/comfort shoes are designed this way, and you will find most have a 1-2″ heel. This should be the most natural for walking, and the “easiest” on your hip & knee joints for the average person.
The MBT style shoes are designed and marketed as a form of “exercise-in-a-shoe”. They purposely make it harder for you to walk, forcing you to use more muscles than you would naturally during a normal gait. This is done by forcing a slightly lowered heel (sort of a reverse high-heel), a very unnatural foot position for walking. Additionally, most experts agree that very flat shoes (ballet flats, flip-flops, etc), while fine on an occasional basis, are detrimental long-term due to overall lack of support. They lack an adequate heel, arch support and foot-bed. Of course, very high heels may have the same shortcomings for the opposite reasons. Any of these shoes may increase forces across your knees & hips.
Any shoe-wear that changes your natural stride can alter your mechanics around your hip & knee. Whether that hurts or helps your problems depends on how your body reacts to wearing them. It is best to gradually introduce yourself to new footwear, starting with short wearing times and increasing that daily until the desired wearing time is achieved comfortably. This is true of all shoes: from MBTs to flats to walking shoes to the highest stilettos.
A good rule of thumb is this: Listen to your body. If wearing any sort of footwear causes your back/hips/knees/ankles/joints to hurt, then your body is telling you to “back off”. This is nearly universally true for all activities and the human body. The “no pain, no gain” mantra for exercising refers specifically to effort, stretching, muscle fatigue & conditioning. You should not do any activity that increases or causes pain inside your joints.
