The facet joint block is both a test and a form of treatment.
A local anaesthetic agent, such as Lidocaine or Novocain, is injected into the facet joint or the small nerve branches that supply the facet joint. This same type of local anaesthetic agent is used by a dentist to numb your jaw or by a doctor when suturing a wound. The Lidocaine numbs the area around the facet joint. If your pain goes away, the doctor can assume that the pathological facet joint is contributing to the problem.