Lt. Col. Kevin Koehler (left) of Pontotoc Miss., an Arkansas National Guard physician on a 90-day rotation to Camp Taji, Iraq explains the structure of the human knee to Sgt. Christopher Walker of York, Pa., a healthcare specialist, with Company C. "Charlie Med," 328th Brigade Support Battalion, 56th Stryker Brigade, June 13, at Camp Taji, north of Baghdad. Walker had just finished a consultation with a patient who complained of knee pain. Koehler practices in Tupelo, Miss.