The bizarre injury occurred just before the hour mark during Racing Metro's 17-15 win at Montpellier, when Mathieu Raynal was caught in a tangle with players.
With his anguished screams clearly audible, players comforted the official who was stretchered off and taken to hospital where scans revealed he had suffered a double fracture to his tibia and fibula.
Raynal was replaced by Vincent Blasco-Baque who officiated the rest of the match.
Paris-based Racing have now won eight league matches on the bounce with their latest success at the Stade Yves du Manoir.
Racing are in fifth, now three points ahead of Montpellier, after stealing a march on their rivals who came into this game level on points. The top six in the table qualify for the play-offs.
Victory for Racing prolongs their remarkable rise this calendar year; Patricio Noriega's side were languishing in 11th in December and were seemingly bracing themselves for a relegation scrap.
But their turnaround in fortunes sees them move level on points with fourth-placed Castres.
In Friday night's match, Masi Masadigo scored the opening try against his former club before Henry Chavancy barged over just before the break. With Olly Barkley and Sebastien Descons sharing the conversions, Racing went in at half-time 17-3 up.
A second-half fightback from Montpellier threatened to derail Racing as Benoit Paillaugue kicked four unanswered penalties, but the visitors clung on to register victory.