No space -- meaning no cartilage between the two bones that make up the knee joint -- can cause tremendous pain.

CNN: What you need to know about total knee replacement

After years of robust financial health, artificial knee- and hip-joint maker Stryker ( SYK) has suffered aches and pains the last couple years.

FORBES: Artifical Knee- And Hip-Joint Maker Stryker Can Stand Tall Again

Joint-captain Chris Cusiter travelled despite a persistent knee injury preventing him from playing in the 24-5 win over a Japan Select on Tuesday.

BBC: Robinson eyes double over Pumas