Most dogs can recover from ligament injuries without surgery.  In the minority of cases where the dog cannot begin to improve joint stability with activity restriction, even with a brace, then surgery is appropriate. Some form of conventional extracapsular stabilizing procedure is the best choice for most dogs who require surgical intervention.  A 'Conventional' stabilization surgical procedure using the standard ortho-suture materials is best for most dogs who need surgery.  But for large high-energy dogs, advances in materials used in stabilization surgery have made it possible to increase the strength of the stabilization by a great deal, making bone-geometry-altering procedures TPLO & TTA obsolete except in rare situations.
I suggest using careful restriction as a first step in determining how best to deal with a dog's ligament injury. This careful restriction for 8 weeks is the best diagnostic tool to determine if the dog will be able to recover well without surgery.  Usually a dog will begin to improve and continue to slowly improve over time when activity is carefully restricted.  Some ups & downs are likely as the weeks go by, but a general direction of improvement shows that the stifle is being re-stabilized by the body's natural ability to heal and recover from injuries. Full recovery will take more time than the original 8 weeks. How long a recovery will take depends on many variables--- severity of injury, size & age of the dog, etc.
When a dog cannot improve significantly during this period of careful restriction, consider getting a custom-made brace.
If improvement still doesn't begin even with the brace, surgery is the next step.
Braces are covered on the FAQ page here at this website.  In most cases I would prefer trying a brace for my dog before I would decide that surgery was necessary.
There are basically two surgical strategies. 
----1) Hold the bones in position at the joint with a surgically installed restraint which will allow near-normal movement of the joint while preventing improper movement.  Tough fibrous scar tissue will then build up around the joint.  This scar tissue will provide long-term stability.  These are called 'Conventional' or 'Traditional' surgeries.
---- 2) Cut the bones and reposition sections of the bones using metal plates or implants to alter the relationship of the bones to each other, changing the tibeal plateau angle at the stifle joint.  The procedures used to do this are TPLO and TTA.
-- Some vets will recommend TPLO or TTA for most or all dogs with ligament injuries.  These very invasive bone altering procedures have much greater risk of serious complications than conventional surgery but do not have superior long-term outcomes.  Please see the 'TPLO / TTA' page here at this website for more information on TPLO / TTA.
This page focuses on Conventional Stabilization Surgery.  There are dozens of intracapsular and extracapsular variations of conventional stabilization. 'Extracapsular' means outside the joint.  'Intracapsular' means inside the joint.  Extracapsular procedures are generally recognized as the best choice among the various conventional procedures in most cases. Extracapsular stabilizations usually use heavy suture similar to nylon fishing line attached to the bones outside the joint to hold the bones in place.  The theory behind all conventional surgeries is that by holding the bones in place at the joint in a way that allows near-normal joint movement, the surgical stabilization will provide conditions under which the body can begin building up the permanent scar tissue stabilization.   For many years vets have used monofilament nylon orthosuture (similar to fishing line) drawn tight and secured, to stabilize the joint in most extracapsular procedures. There are now stronger materials available, but for most dogs the standard nylon orthosuture is still a good choice. For large high-energy dogs you will want to consider other orthosuture materials which are described lower on this page. The installed orthosuture strands will provide temporary stability while over a period of months the dog's body builds up tough fibrous scar tissue which will permanently support the joint. The surgically installed orthosuture will always stretch or break after several months. It is not meant to be a permanent stabilization. Its function is to give the body the temporary stability it needs to get started on establishing the permanent stabilizing scar tissue. Whether or not surgery is needed to get a start on re-stabilizing the joint, ultimately it is the dog's own healing process which provides the new scar tissue support for the joint.
Unlike human ligament surgeries, dog ligament surgeries do not re-attach or permanently replace the ligaments. Some vets will fail to make this clear to their clients, leading people to believe that the surgery is a 'repair' in the sense that the damaged ligaments will be restored to function or permanently replaced.  Ironically, a statement that some vets use in recommending surgery is "Those ligaments won't repair themselves."  It's true that ruptured ligaments don't repair themselves, but it's also true that the surgery the vet wants to do isn't going to repair the ligaments either. Ligament repair or replacement with surgery is just not an option for dogs.*  The ligaments, once fully torn, are gone forever. Anyone who tries to tell you otherwise is either mistaken or being deceitful.  Permanent stabilization of the joint depends on the tough new fibrous scar tissue described above.
*---- There is one exception to this.  In rare cases where the ligament remains whole but has pulled loose a chip of bone which is large enough for reattachment.  If that has happened then a repair is possible by reattaching the bone chip.  But that is very rare.  If the ligament itself is torn, as is usually the case, repair of the ligament is not possible.
Here's an analogy for the change in stabilization method:
---- Imagine you have an umbrella which keeps you dry in the rain, but a storm wind destroys your umbrella.  It is ruined beyond repair.  It is not possible to get another umbrella, but you can get a raincoat which has a hood.  The raincoat is not an umbrella, but it does the same job the umbrella did of keeping you dry. 
----  When the ligament is torn, it is not possible to repair it or replace it with another ligament, but it is possible to accomplish the function the ligament formerly accomplished in a different way.  By restricting activity so that tough new fibrous scar tissue will be able to build up around the joint to hold the bones, proper movement will be possible after recovery while improper movement will be prevented.
Clicking? Popping?
People are often incorrectly told that a clicking or popping sound in the joint is doubtless a sign that surgery on the meniscus is required.  In fact, these sounds may indicate meniscal injury, or they may have a different cause.  And if there is meniscal damage, surgery may or may not be best.  People are sometimes led to believe that the meniscus will be repaired by surgery when in fact meniscal surgery will simply remove part or all of the meniscus.  Removal of part or all of the meniscus will inevitably result in arthritic changes for the joint in the long-term, so this is not something that should be done without good cause.  Sometimes removal of part or all of the meniscus is the best choice, depending on the severity of the injury to the meniscus, but this must be carefully considered. Inappropriate surgeries are often recommended.
These pages are linked in the column at left:
 "Clicking / Popping"
"The Dog Meniscus"
When joint instability requires surgery, then a conventional stabilization surgery is the best choice for most dogs.  But until recently the best choice for large highly active dogs might have been one of the more invasive bone-geometry-altering procedures TPLO or TTA.  This was because the usual synthetic monofilament ortho-suture used in the conventional procedure would be likely to fail with a large, very active dog.  However, there have been advances in the materials available for conventional stabilizing surgery which make conventional stabilizing surgery appropriate for these large high-energy dogs.  These advances make it possible to avoid the changes in bone structure involved in TPLO / TTA and the associated risks.
---- Advanced ortho suture materials* are much more resistant to stretching and breaking when used in stifle stabilizations than the standard ortho-suture monofilament material.  Improved methods of securing the suture material also add to the overall increase in the capacity of the stabilization to resist failure.
---- In light of these new developments, TPLOs & TTAs are no longer a reasonable choice for the majority of dogs for whom they are still being recommended.  These very invasive surgeries have special risks of very serious complications including catastrophic failure potentially resulting in amputation or death.  They have this disadvantage without any longer providing a counterbalancing advantage.  TPLO & TTA used to be defendable as appropriate for large highly active dogs in the past when conventional surgeries had a much greater risk of failure in large active dogs. Today, with advances in conventional stabilization available to us, TPLO & TTA are only rarely a good choice.  (When is TPLO appropriate? Please go to the 'TPLO/TTA' page here at this website and look for the section on TPA.)
*-- Examples of advanced orthosuture materials include Ethibond [Ethicon, Somerville, NJ], FiberTape and FiberWire [Arthrex, Naples, FL], OrthoFiber [Securos, Fiskdale, MA], Orthocord [DePuy-Mitek, Norwood, MA], Hi-Fi [ConMed Linvatec, Largo, FL], Ultrabraid [Smith & Nephew, Andover, MA], ForceFiber [Stryker Endoscopy, San Jose, CA], MagnumWire [ArthroCare, Sunnyvale, CA], MaxBraid PE [Arthrotek, Warsaw, IN]
The Arthrex company, a maker of surgical equipment, developed a high-strength stifle stabilization procedure they call 'TightRope CCL'.  Arthrex sells a 'TightRope' kit for surgeons.
Here is a link to a descriptive white paper on TightRope:
'Securos' is another company which makes surgical equipment and supplies. They call their high-strength stabilization procedure "Securos XGEN CCR" and sell a kit for surgeons to use in performing it.  Here is a site with a description of their procedure.  This is similar to 'TightRope' but done with Securos' high strength suture called 'OrthoFiber' and other Securos materials:
Both of the above are minimally invasive types of Lateral Suture Stabilization (or LSS) which is a kind of extracapsular stabilization of the stifle.
---- Conventional stabilizations using the new high-strength materials are fairly new and not universally available.  If your dog needs a high-strength stabilization, find a surgeon you like who has experience with conventional stabilization using high strength materials.  His preferences in materials will be best in a surgery he performs. 
Here's some information on TightRope CCL from Arthrex:
<<"The components of TightRope CCL consist of a stainless steel toggle
button, a round suture button and FiberTape. FiberTape is an ultra-
high strength tape utilizing a structure similar to FiberWire
suture. The weave of the FiberTape allows for smooth, atraumatic
passing through tissue and bone, and desirable tying
characteristics. Testing has shown FiberTape to have an ultimate
load of 225 lbs. and high stiffness characteristics."
"The TightRope CCL technique was developed to provide a minimally invasive method for extracapsular stabilization of the cranial cruciate ligament-deficient canine stifle. TightRope CCL seeks to optimize the lateral suture stabilization technique by employing bone-to-bone fixation, an implant with superior strength and stiffness designed specifically for ligament repair, and a method for consistent isometric implant placement. As such, TightRope CCL can counteract cranial tibial thrust, drawer, and internal rotation, while providing optimal joint range of motion.">>
Are There Any Special Risks associated with the use of the advanced orthosutures?
Yes. First there is increased infection risk.  The advanced high-strength orthosutures are woven materials.  These have a greater potential to harbor bacteria than does the monofilament nylon orthosuture commonly used in extracapsular stabilizations.   If an infection gets a start inside the leg during or after surgery, their woven nature makes the infection harder to treat.  (Bacteria hide-out in the nooks & crannies of the weave.)  It is sometimes necessary to remove the orthosuture in an additional surgery if the infection cannot be controlled with drugs.  Being meticulous about proper aseptic technique in the operating room greatly reduces infection risk.  Nevertheless, this is a risk you have with woven orthosuture but not with monofilament.  
---- Also, the advanced orthosuture can be abrasive where it comes into contact with bone.  This has led to problems in some dogs who have had the TightRope procedure.  The TightRope FiberTape has worn the edges of the drilled holes in the bone over time.  This is not a widespread problem.  Reason tells us this will be a self-limiting problem in most instances since as the FiberTape wears down the edges of the drilled holes it will inevitably loosen the Fibertape, which would stop the abrasion.  In most instances this would occur after the joint had been sufficiently re-stabilized by the natural buildup of scar tissue (which makes all orthosuture installations temporary stabilizations) so there would be no long-term negative effect.  But in some dogs there has clearly been an abrasion of the bone which has occured rapidly enough to create a problem requiring additional surgery.
---- The Securos XGEN CCR system uses implanted metal collars called 'PROS' at the ends of the bone tunnels which eliminate the bone abrasion problem.  How this works can be seen in the above linked guide to the Securos XGEN CCR  
Should Fido have one of these high-strength procedures?  Or is the standard nylon orthosuture a better choice in Fido's case?
---- In deciding on a type of surgery, it is important to understand that all the stabilizing surgeries, including TightRope & XGEN CCR, have only a temporary purpose.  They are not expected to act permanently as support for the joint.  They provide a temporary stabilization which will do its job for several months as new fibrous scar tissue builds up to provide permanent stabilization for the joint.  Therefore the reason to choose the greater strength of TR's FiberTape, or XGEN's OrthoFiber, or any other advanced suture material is that your dog is a large high-energy dog who is likely to put too much stress on the temporary stabilization in those months of recovery following surgery before Fido's body has had time to build up that new scar tissue support.  There is no other reason to prefer the advanced materials to monofilament nylon.  Using one of the new superior orthosutures (including FiberTape and OrthoFiber) will not provide better long-term stabilization for the injured joint.  Long term stabilization is the result of the scar tissue development.  Its strength is not dependent on the type of surgically installed materials used for the temporary surgical stabilization.
---- Some dogs are much bouncier & harder to restrict post-op than others.  If your large dog is a relatively easy-going large dog, I think that as long as you are careful to prevent excessive stresses during the several months of his post-op recovery, an extracapsular stabilization done with monofilament orthosuture would be fine.  And for smaller dogs there is usually no advantage in the advanced materials since the nylon ortho-suture will not be over-stressed.  But for a large high-energy dog who will unavoidably put a lot of pressure on the joint during the post-op months, extracapsular stabilization using one of the high strength advanced ortho-sutures would be the best choice
Dog Size as it relates to TightRope Suitablity
The bulk of 'FiberTape' is greater than that of other ortho-suture materials and this limits the size of dogs who can have the 'TightRope' procedure.  TR requires that a dog be larger than approximately 30 to 40 pounds. This is a rough estimate of the minimum size of dog who could have the TightRope procedure.  The actual limiting factor is the drill tunnel size to accommodate the FiberTape.  The drilled tunnel required for the FiberTape is 3.6 mm and you do not want a tunnel more than 1/3 the diameter/width of the bone. The 30-40 pound weight is just a rule of thumb for that.  If a dog is 30-40 lbs then the vet should measure the femur on X-ray and if it is 12 mm or above then TightRope is size-appropriate for that dog.
The kit for "MiniTightRope" is intended for smaller dogs.  The 'MiniTR' involves drilling a 2.7 mm tunnel, and so can be used on dogs with femurs measuring 9 to 12 mm. Theoretically, the miniTR might be preferred to a standard stabilization based on many of the same factors as for large dogs, ie bone-to-bone fixation, isometry, less soft tissue disruption. But TRs are harder to accurately place as the patient’s bones get smaller, and the expected outcome for small dogs who have extracapsular stabilization with nylon monofilament is excellent since small dogs will not put great stresses on the stabilizing ortho-suture.  Therefore I do not see mini-TightRope as useful in general.
Cost of TightRope or Securos XGEN CCR?
The cost for these procedures varies.  At this point you may find that because they are still fairly new they are only being done near you by a few ortho-specialist surgeons who charge more money for their time.  Vet-surgeons set their own prices for surgery according to what they can convince clients to pay.  I expect that in the future more & more vets will be doing these procedures and there will be more competition in price along with wider availability.
---- Costs for these procedures today should be significantly lower than TPLO / TTA costs, but somewhat higher than standard conventional stabilization surgery costs.  Reported TightRope costs vary from around $700 (US dollars) up to several thousand dollars for the total bill.  As of March 2009, at one major US state university vet facility, the total bill for TR done by top ortho surgeons including exam, diagnostics, anesthesia, scope, surgery, TR implant, ICU, bandages, meds, would be $2200-2500 (US dollars). 
---- Some surgical practices will include a number of weeks of post-op hydrotherapy sessions and/or other rehab therapy as part of a package price for the surgery & recovery.  It is important when comparing prices to understand what is included in the quoted price.
---- A TR procedure takes about one third the time it takes to do a TPLO.  About 20 minutes for TR as opposed to an hour for a TPLO.  This, together with the lesser complexity of the procedures when compared to TPLO or TTA, should result in considerably lower costs to clients.  But some surgeons who are currently making very large profits doing TPLO can be expected to try to charge similar outrageous prices for the new stabilization procedures if they can convince people to pay those prices.  I hear of that happening now.   A profiteer is a profiteer, whatever he is overcharging for.   When looking for a surgeon, remember that a higher price does not mean a better surgeon.
"Max, After reading about the new Securos XGEN CCR and the TightRope procedure and the use of other advanced materials in conventional stabilization surgeries on your website, I talked about it with the ortho-surgeon my vet recommended .  He says that these are too new.  That because they are new they may have problems that haven't become apparent yet.  He says that TPLO has been around for years so he knows what could go wrong in doing TPLO.  He wants to do TPLO on my dog.  Isn't it better to go with a surgery that is not so new?....."
---- It is usually wisest to be cautious about new techniques and materials until they have a history of success.  But these are not really brand-new procedures.  They are basically Lateral Suture Stabilizations (LSSs), which is a well-known type of extracapsular stabilization which has been used for many years.  With the new materials the LSS has been made more suitable for large highly-energy dogs.  In my opinion the claim that procedures using new materials are too new to be trusted is not at all convincing.  The potential complications associated with TPLO and TTA can be much more serious than those with any conventional stifle surgery, and I believe it is appropriate for me to highly recommend conventional stabilizations done with these stronger materials as being very much preferable to TPLO or TTA for large high-energy dogs in almost all cases. 
---- The adoption of new methods and materials can move slowly in medical / surgical treatment.  When the established procedures are big money-makers for the docs who do them, the struggle for the adoption of new & superior methods is especially difficult.  There are going to be a lot of surgeons out there still telling people that their dog needs a TPLO when in truth the dog would be much better off with a less invasive and less risky conventional surgery using either nylon monofilament ortho-suture or the new stronger materials. I very much prefer a surgery that does not alter the bone structure as TPLO & TTA do, and does not expose the dogs to the substantial risks inherent in the much more invasive TPLO & TTA.  
It is very important to be careful about proper activity restriction during the months of post-op recovery.  Activity must be sufficiently restricted to allow the new supporting scar tissue to slowly develop without being damaged by excessive stresses on the joint.  This takes months.  People sometimes allow too much activity too soon.  This can result in serious problems.  Some surgeons and physical therapists are too aggressive in their recommendations for increases in post-op activity.  Dogs who are not restricted properly will have greatly increased risk of failure.  A slow, cautious, watchful approach to activity increases during recovery is best by far whether the dog is recovering after surgery or without surgical intervention. The stabilizing material used in conventional surgeries will inevitably stretch, loosen, or break.  Greater amounts of activity and higher stresses will speed the lessening of effectiveness of the suture stabilization.  If the dog's body has not yet fully developed new stabilizing scar tissue at the stifle when this happens, there will be renewed instability at the stifle.  A slow cautious approach to increasing activity during the post-op recovery is best.  The amount of time needed will vary with the dog's age and size, so it is not possible to state a certain length of time will be needed to be confident that the re-stabilized stifle is safe from re-injury. Larger & older dogs will require more time.  Being cautious is always best when deciding on activity for a recovering dog.
Re-Injury After Conventional Surgical Stabilization?
There's more about how to handle this on the FAQ page.
Finding The Right Surgeon
You will be able to discover whether a vet is familar with new ortho-suture materials by asking what materials the vet would use in the conventional procedure for your dog.  With small dogs and most non-highly-active dogs, the standard monofilament nylon ortho-suture (like fishing line) will be fine.  But if your dog is a highly active large dog, the surgeon should be intending to use advanced materials and should be able to tell you about the type of ortho-suture & other materials he would use.  If you ask and he doesn't have good answers, he is not the right surgeon for your dog. 
---- Bear in mind that both Arthrex and Securos manufacture many different surgical materials.  If a surgeon says to you "I would use Securos orthosuture in the stabilization" that may mean he intends to use standard nylon monofilament suture he bought from Securos rather than the XGEN CCR kit you might assume.  Be sure you are getting a clear description of exactly what the surgeon intends.  If you get the impression that he is not being informative and would prefer you to trust him without his explaining, I'd find a different surgeon. 
There may be a vet referal service in your area which would have the names of surgeons who list themselves with the service as doing TightRope CCL or Securos XGEN CCR. 
Many vet practices which are listed with referal services as performing TightRope or Securos's XGEN CCR may have several vets in the practice but only one of them may be experienced in or interested in these procedures.  I have heard of people making an appointment at a vet practice which is said to do one of the advanced conventional procedures, but when they come in with their dog they are seen by a vet who knows nothing about that and immediately tries to sell them a TPLO.  When you make an appointment, be sure that you are making an appointment to see a vet who does TightRope or XGEN CCR, not an appointment with whichever vet from the practice is available.