There remains those situations characterized by multidirectional instability, which have failed to respond satisfactorily to rehabilitation, falling under the AMBRI classification previously noted. This is usually due to an overstretched and redundant capsule which no longer offers stability or support. Traditionally, this has responded well to a 'reefing' procedure known as an open inferior capsular shift. More recently, the procedure has been carried out as an arthroscopic procedure, rather than open surgery, again with comparable results. Most recently, the procedure has been carried out using radio frequency technology to shrink the redundant shoulder capsule (thermal capsular shrinkage); while long-term results of this development are currently unproven, recent studies show thermal capsular shrinkage have higher failure rates with the highest number of cases of instability recurrence and re-operation.