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Patella Luxation Surgery Overview
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Wedge Sulcoplasty
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Information on the condition and its management options.

Patella luxation is a common orthopaedic condition in dogs and is the result of malalignment of the quadriceps mechanism, patella tendon insertion and the trochlear groove. The condition is the result of a developmental conformational abnormality. The majority of patella luxation cases in small breed dogs are medial, while lateral patella luxation is more common in large breed dogs.

When to consider operating?

Medial patella luxation can cause a range of severities of lameness. Commonly we see Terrier and toy breeds ‘skipping’ as they run due to the patella luxating in and out of the trochlear groove spontaneously. In other dogs luxation can result in acute non-weight bearing lameness and pain. Indication for surgery is decided on a case by case basis and not simply on the grade/severity. As a general rule cases with grade II/IV and above benefit from surgical intervention.

How is patella luxation graded?

Grade l. Animals in this group have a patella that can be luxated manually but returns to its normal position within the trochlear groove when released.

Grade II. The patella is located for the majority of the time in the trochlear groove, but can luxate during locomotion. The patella tends to remain luxated for a few strides before spontaneously reducing, causing the classic skipping lameness.

Grade III. The patella is luxated most of the time. It can be reduced manually but will re-luxate when the manual pressure of reduction is removed.

Grade IV. The patella is be luxated all the time and manual reduction of the patella within the groove is impossible even with the leg in full extension.

How is the condition corrected?

There are five surgical treatment methods and they are often utilised in combination. The method(s) utilised is dependant on the severity of an individual's anatomical abnormalities; when decision making we take into account:

  • the degree of proximal tibial torsion

  • trochlear groove depth and cartilage damage.

  • Femoral varus and/or torsion.

  • Abnormalities of the medial and lateral retaining fascia.

Which surgery will be required?

The five treatment options are:

  1. Tibial Crest Transposition (TCT). An osteotomy is made in the tibial crest, and the fragment is transposed in the opposite direction to the direction of luxation to realign the quadriceps mechanism and patella tendon insertion to centralise on the trochlear groove.

  2. Trochlear groove sulcoplasty. By deepening the trochlear groove through a wedge or block resection we create a better ‘cradle’ to house the patella.

  3. Fascial release and/or imbrication. Often the soft tissue surrounding the patella have become contracted on the side of luxation, and lax on the contralateral side to the luxation. Appropriate imbrication and release may be necessary.

  4. Distal Femoral Osteotomy (DFO)/ Proximal Tibial Osteotomy (PTO). In some dogs with higher grade luxations where there are marked anatomical defects, a TCT alone may be inadequate to correct alignment. These cases require a pre-planned osteotomy to resolve the anatomical deformation, often following computed tomography (CT), that is stabilized with a bone plate.

  5. Patella Groove Replacement (PGR). Rarely, the damage to the trochlear groove and/or articular cartilage is so advanced that simply correcting alignment abnormalities is inadequate to relieve the morbidity associated with this advanced disease. In these cases a special Kyon groove implant is inserted following removal of the existing bone/cartilage.

What are the potential surgical complications?

As with any orthopaedic procedure where metal implants are placed there is a chance of implants causing irritation, most commonly in TCTs as a result of the pin backing out or irritating the soft tissue overlying the implant - this happens in around 8% of cases and requires removal of implants, though this is a relatively simple procedure. Surgical site infection, as with any surgery, is a potential risk. Re-luxation of the patella is also occasionally seen following surgery and very rarely tibial fracture can occur.

See our Audit for surgical site infection rates.

See our Surgical preparation and antibacterial protocol for details of how we aim to minimise perioperative infection.

Patella luxation online video

Related Cases
Patella Groove Replacement (PGR) in a Staffordshire Bull Terrier

Patella Groove Replacement (PGR) is a partial joint replacement surgery where the trochlear groove of the stifle is replaced with a prosthesis. It is indicated as a treatment for chronic patello-femoral pain due to degenerative joint disease, and can also be used as a treatment for patella luxation (Dokic)

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