TORRINGTON
ORTHOPAEDICS
Referral Orthopaedic Service for 21 years

PATELLAR LUXATION

Also known as slipping Knee Cap.

Some dogs with Patellar Luxation may also have Cranial Cruciate Ligament pathology and this may need management at the same time as the surgery for Patellar Luxation. In some cases, the state of the Cruciate may not be known until the time of surgery. These dogs will generally appear lame at all times and stiff on rising from rest. X ray findings along with palpation of the joint under anaesthesia may help to identify the presence of this additional pathology before surgery.

I think my dog has Patellar Luxation

Certainly in grades 2 and over and in those patients with cartilage loss, surgery is the optimal form of management. It is not possible to use Rehabilitation or medical therapy instead of surgery in these patients. Some patients with grade 1 patella are not managed surgically especially if the problem is very intermittent and does not appear to be having a significant impact on quality of life. This is not always the case however and as untreated Grade 1 Patellar Luxation may become worse or put the Cruciate ligament at risk, surgery may still be advisable.

Surgical Options

  • Tibial Tuberosity Transposition: This is indicated in almost every patient with Patellar Luxation. Recurrence of patellar luxation after surgery can often be attributed to failure to perform this procedure. In this procedure the tip of the shin bone is separated from the shin bone and moved to the side opposite the luxation. It is held in position by two small pins. The tip of the shin bone will heal in this new position over 4-6 weeks after the surgery.
  • Deepening the Groove (Trochleoplasty or Sulcoplasty): This is often performed too as the absence of the pressure from the patella combined with its movement over the ridge can result in a shallow groove. Rarely will we perform this without Tibial Tuberosity Transposition as failure to combine these is associated with a higher rate of recurrence of Patellar Luxation.
  • Tightening the soft tissues opposite the side of luxation: The joint capsule becomes stretched on the side away from the dislocation. This extra tissue is reduced by creating a “tuck” in the joint capsule. This procedure is never (except where patellar luxation is definitely due to trauma to these tissues) performed alone. If the other procedures are not performed, the “tuck” will stretch and the luxation will recur.
  • Releasing the soft tissues on the side of the dislocation: This is required in most grade 3 patients and some grade 2 patients. If the patella is in an abnormal position for long periods the tissue to the side of the patella will shorten and this may need to be release. The quadriceps muscle group is often released at the same time.
  • Femoral and/or Tibial Osteotomy: In the higher grades (3 and 4), the femur and tibia are usually bowed or bent. In this procedure the Femur and sometimes the Tibia are fractured and straightened. Plates are used to allow the bones to heal with this new shape.
  • Patella Groove Replacement (PGR): This is discussed in more detail below. It was devised and designed by Kyon AG It is particularly indicated for dogs that have lost cartilage on the underside of the patella. As mentioned previously this is often seen in Bull type dogs. Andy Torrington has performed the most of these surgeries in the UK and lectures on this surgery, helping to train other surgeons to perform this procedure.

Post Operative Management

As with other Orthopaedic surgeries a period of rest is required after Patellar surgery. This allows any fractures to heal and the soft tissues to become strong. The period of rest will rarely exceed 12 weeks. In some patients, cage confinement may be necessary but this is not common.

  • Weeks 1 and 2: House and Garden only permitted. Whilst in the garden lead restraint should be used at all times. Periods in the garden may be frequent but should not exceed 5 minutes. Stairs and getting on and off furniture must be avoided.
  • Weeks 3 and 4: In addition to the above, dogs may have up to three, five minute on lead walks per day. Stairs and furniture must be avoided.
  • Weeks 5 and 6: The walks are extended to 15 minutes three times daily on lead. No stairs and no furniture access.
  • Weeks 7-12: Walks are extended gradually back to normal during this period. Lead restraint is still used and whilst stairs can be accessed this should be infrequent.
  • 12+ weeks: Normal lifestyle in all respects.

PATELLA GROOVE REPLACEMENT

In this procedure we replace the groove with a geometrically perfect, diamond coated Titanium artificial groove. This procedure has revolutionised the way we manage Patellar Luxation seen in association with loss of cartilage on the underside of the patella. In patients with cartilage loss, there is continuous friction between the patella and the ridge of the femur. This friction causes heat and pain. The diamond coating on the groove results in an almost frictionless gliding between the patella and the artificial groove. This eliminates heating and pain. The perfect geometry of the groove holds the patella perfectly in the groove throughout flexion and extension of the joint.

This procedure can also be helpful to revise previous unsuccessful surgery for patellar luxation and to avoid performing the more complex procedures such as Femoral and Tibial osteotomies as the groove can be positioned (in most dogs) perfectly in line with the patella without changing the shape of these large bones.

This shows the positioning of the Prosthesis in the knee, with in this case fours screws anchoring the base of the prosthesis to the femur. Bone will grow into the perforated base plate and ultimately it will be this that holds the groove in place. This process of integration takes around 8-10 weeks in most patients.

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Torrington Orthopaedics Ltd, Mission Street, Brighouse, West Yorkshire, HD6 1NQ. 01484 404770
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