Cruciate repair – What do I need to know?

The cruciate ligaments are ligaments within the knee (stifle) that stop the bones under the knee (the tibia and fibula) sliding back and forth against the bone above the joint (the femur). The are arranged in a “cross” arrangement – hence “cruciate”. The cranial, or anterior, cruciate ligament (CrCL / ACL) is particularly prone to damage in dogs- especially in athletic or overweight dogs, or dogs on steroids.

A ruptured cruciate ligament

Rupture can cause pain, lameness and ultimately arthritis. So what can we do to help this?

Conservative Management (aka doing nothing)
Pros- cheap, most dogs will get a little better over months, esp smaller dogs. Cons- probably will be lame for rest of life, will develop moderate/ severe arthritis. Only really suitable for dogs < 15kg. 30% return to full function.

Inject blood into joint
Old fashioned remedy and no better than doing nothing.

Capsuar imbrication (“tighten” up surrounding ligaments)
Old fashioned remedy and no better than doing nothing

Lateral Suture
Originally described by DeAngelis and subsequently refined by Flo, Olmstead and many others, some kind of lateral suture is the most common means of stabilising the Cranial Cruciate Ligament(CrCL) deficient stifle.

By placing some kind of prosthesis from the lateral femur to the proximal tibia in the same plane as the CrCL the stifle becomes stable and maintains a full range of movement. Various materials have been tried over the years; braided nylon, monofilament nylon, stainless steel wire and some of the long term absorbable sutures. All typically fail at between 6 or 8 weeks. This failure does not affect the outcome of the procedure, stability coming as it does from fibrosis in the long term.

The current material of choice is monofilament nylon leader line. This material is stronger and more resistant to abrasion than normal monofilament nylon. Currently choice of leader line is between different brands rather than appropriately specified materials. 50% return to full function.

Over The Top
Replacement of cruciate with patellar ligament or fascia lata (essentially drawn through joint and fixed to femur with spiky washer)- incudes Paatsama, modified Paatsama and over the top technique in this. In all cases the replacement ligament undergoes degeneration, and needs stabilisation and optimal technique to encourage revascularsation.

Secure attachment of the graft to the femur is difficult. Screws and spiky washers or ligament staples are more secure than sutures. The graft weakens during the first 4 or 5 weeks as revascularisation takes place. Typically the recovering dog is eager to stress the graft at a time of minimal strength. Intra-articular manipulations, to pass the graft, carry potentially more serious post op complications than extra-capsular techniques.

It is possible to augment the autograft with a lateral suture to protect the graft during the revascularisation phase. Theoretically the graft should be up to strength when the lateral suture fails. 60% return to full function (better results in smaller dogs).

Tibial tuberosity advancement (either Rapid or Modified Macquet) TTA
Changes forces acting through stifle by advancing the tibial crest. Suitable for all but the largest breeds or those with a steep tibial plateau angle. 90-95% return to full function. Fewer and lesser complications compared to TPLO. 

Tibial Plateau Levelling Osteotomy (TPLO)
changes forces acting through stifle by cutting off the top of the tibia, rotating it slightly, and then reattaching it with a plate. 95% return to full function. Can have dramatic post op complications if not done correctly.

Triple Tibial Osteotomy (mix of TTA and TPLO)
Tibia is cut to adjust the angles within the stifle.

All the above methods work better on a dog that has lost weight! Concurrent stem cell therapy will also improve results.

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