MLG ENCOUNTERS TURB IN CLOUDS ON DSCNT. FLT ATTENDANT INJURED.

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WE WERE DSNDING TO MAKE A XING RESTRICTION ASSIGNED BY ATC. NORMAL PROFILE. AIR WAS GENERALLY SMOOTH. RADAR WAS ON BUT PAINTING NO RETURNS. IT HAD BEEN WORKING WELL FOR THE PREVIOUS 3 LEGS. SEAT BELT SIGN WAS ON DUE TO OUR DSNDING INTO THE TERMINAL AREA. IT WAS DARK BUT A WALL OF CLOUDS APPEARED IN FRONT OF US AS WE DSNDED THROUGH 14000 FT. THE CLOUD TOPS WERE WELL ABOVE US AND THERE WAS NO WAY TO AVOID THE CLOUDS WITHOUT TAKING EVASIVE ACTION; SO WE CONTINUED. 2 MODERATE 'JOLTS' WERE FELT IN QUICK SUCCESSION AND THE AIR WAS AGAIN GENERALLY SMOOTH. HOWEVER; THE TURB; WHICH I WOULD CLASSIFY AS MODERATE; KNOCKED ALL 3 OF OUR FLT ATTENDANTS TO THE FLOOR. 1 FLT ATTENDANT AT MID-CABIN SUFFERED A HEAD LACERATION AND A BROKEN LEG. NO OTHER INJURIES OCCURRED. THE SMOOTH AIR AND SUDDEN ONSET OF THE TURB CONTRIBUTED TO THE INJURIES SUFFERED BY THE FLT ATTENDANT IN MY OPINION. WE GO THROUGH CLOUDS ALL THE TIME; BUT FEW HAVE 'ROCK' IN THEM LIKE THE ONES I ENCOUNTERED. THE TURB WAS RPTED TO ATC. ANOTHER ACFT IN THE VICINITY EXPERIENCED SIMILAR CONDITIONS; TOO. GIVEN THE SAME SITUATION AGAIN WE WOULD NOT HAVE FLOWN THE AIRPLANE ANY DIFFERENTLY. THE CLOUDS GAVE NO INDICATION OF CONTAINING TURB OUT OF THE ORDINARY. WOULD DOPPLER RADAR DETECT TURB AT 14000 FT? IT IS MY UNDERSTANDING THAT GND-BASED DOPPLER RADAR IS FAIRLY SHORT RANGED. DOES THERE EXIST ANY COST-EFFECTIVE MEANS TO INSTALL TUB DETECTION EQUIP IN AIR CARRIER ACFT? SUPPLEMENTAL INFO FROM ACN 210279: AN AMBULANCE MET US AND TURNS OUT SHE HAD 2 BROKEN BONES IN HER L ANKLE. ALL RPTS MADE. I KNOW OF NOTHING I COULD HAVE DONE TO PREVENT IT BUT STILL FEEL ROTTEN.