Function

One of the main goals in Physical Therapy is the restoration of function. Here are some milestones we are looking to achieve with total hip and knee replacements (respectively).

Source Norkin, C. C., White, D.J. (2003). Measurement of joint motion: A guide to goniometry (3rd ed.). (not exactly the proper way to cite, but its the best I got at 5:34 AM and yes I realize and I want those who do not know that a textbook is a secondary source since they are citing other resources and bringing it all together, but convenience is good too)

Hip flexion range of motion (ROM) required for functional activities:
-walking on level surfaces: 0-44°
-ascending stairs: 47-66°
-descending stairs: 66°
According to Magee, ideal functional ROM of the hip include 120° into flexion, 0° of abduction, and 20° of lateral rotation (or external rotation - I wish they would just call it one thing!)
-sitting in a chair: 112°
-putting on socks: 120° flexion, 20° abduction, 20° lateral rotation (sartorius muscle!)

Knee flexion ROM necessary for functional activities:
-walk on level surfaces: 63.1°
-ascend stairs: 92.9°
-descend stairs: 86.9°
-rise from chair: 90.1°
-sit in chair: 93°
-tie shoes: 106°
-lift object from floor: 117°
-putting on socks: 117°

I was going to put pictures of all these so you could all get a visualization along with these but instead I wanted to put me pitching broken down versus Brandon Webb of the Arizona Diamondbacks, enjoy :-D

PS, this is not my best biomechanics ever, I opened up my hips too early and pointed my lead knee inwards as the two most obvious problems, see if you can find some more (click on image to enlarge)!