As the Baby Boomer generation ages, more and more joint replacement surgeries take place each year. Hip replacement surgery is the gold standard of all joint replacement surgeries, with many patients able to walk just a few hours after surgery and return home the very next day. In contrast, knee replacement surgery usually requires hospital stays of several days, followed by weeks to months of physical therapy. What best explains why the recovery after hip replacement surgery is so much faster than after knee replacement surgery?

Question

A.  The hip joint is more superficial and more accessible to surgeons than the knee joint.
B.  The hip only moves in one direction, and recovery of one motion is easier than recovering movement in many directions.
C.  The upper end of the thigh bone has less overall surface contact with the hip bone than its lower end has in the knee with bones of the lower leg.
D.  The knee joint is stabilized by many more structures (many of which have to be cut) than the hip joint.
E.  The knee is a type of combination joint, which are difficult to replace.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you know about the structure of the knee and hip? What other information is related to the question?

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  The knee joint is stabilized by many more structures (many of which have to be cut) than the hip joint.

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the structure of the knee and hip.
· What type of thinking is required?
        o You are being asked to apply your knowledge about the structure of the knee and hip.

Gather Content
· What do you know about the structure of the knee and hip? What other information is related to the question?
        o The hip has a wide range of motion, able to rotate in three dimensions. In contrast, the knee, just moves forward and backwards. The hip has a few tendons and muscles to stabilize it and hold the ball in the socket. The knee has multiple tendons and muscles that attach to the joint and stabilize it.

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
        o The knee joint is stabilized by many more structures (many of which have to be cut) than the hip joint. Because of this it takes longer for a patient to heal from the damage done by a knee replacement than a hip replacement.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to apply your knowledge about the structure of the knee and hip. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that the hip had less surface area in contact than the knee? Did you think that the hip has a smaller range of motion than the knee?