There is controversy amongst surgeons regarding the need to reconstruct all cruciate ruptures.
Because it is now well established that the laxity one gets with a torn cruciate is associated with a high incidence of meniscal tears, many surgeons will not hesitate to advise reconstruction in ALL cases. But other surgeons will assess the degree of risk in relation to the level of activity of the patient, arguing that a sedentary middle aged or elderly patient can cope with the laxity and is not likely to engage in activities forceful enough to go on to meniscal damage.
Primary repair has largely been discredited - sewing the two ends of the old ligament together just does not work adequately. Occasionally if the cruciate and its bony attachment have broken away from the main bone a surgeon may get away with a repair that screws back the bony fragment. But mostly the old ligament is replaced with a graft. The most commonly performed procedure for a torn cruciate is the patellar tendon graft (PTG), also called bone-patellar tendon-bone (BPTB) graft, although the leading centres have probably all moved on to use hamstrings grafting. Each has its own complications and indications.
There is general agreement that in skilled hands most people can get close to a return to normal function if the procedure is without complications and the post-operative physiotherapy protocol is adhered to.