Case Studies

Patellar Luxation and DFO

Patellar Luxation and DFO


“The Case of the Bow-Legged Lab”

Distal femoral osteotomy (DFO) is a surgical procedure to correct limb malalignment for the treatment of medial patella luxation in dogs. A unique modification of the technique was developed by Dr. Kirk Wendelburg at Animal Specialty Group.

1. Referral:

“Kirby” is a three-year old neutered male Labrador Retriever who was referred for a chronic, grade 4 medial patella luxation (MPL). He was acquired by his owner one year ago and always had an “odd” gait with a left rear limb lameness. Seven months prior to presentation, Kirby was diagnosed with a medial patella luxation and was operated on three times over the period of four months in an attempt to correct the problem. Each correction attempt had failed, and at the time of presentation to Animal Specialty Group, Kirby had progressed to minimal or non-weight bearing on the affected limb. Although he was also diagnosed with hip dysplasia of the opposite limb, he had to rely upon this limb load to majority of his rear limb weight.

2. Exam:

The physical exam was unremarkable except for a moderate to severe weight bearing lameness of the left rear limb. The left stifle had a grade 4 medial patella luxation with significant pain and crepitus on palpation along with severe joint effusion. There was a three inch decrease in thigh circumference when compared to the opposite limb. Other findings revealed pain on extension of the right coxofemoral joint, and pain on flexion of both elbows.

3. Diagnosis:

  1. Left grade 4 medial patellar luxation with failure of three prior surgical repairs, which included (i) tibial tuberosity transposition, (ii) femoral trochleoplasty, (iii) lateral derotational suture and imbrication, and (iv) a medial desmotomy.
  2. Right canine hip dysplasia with moderate secondary osteoarthritis
  3. Probable bilateral elbow dysplasia

4. Treatment:

Surgical revision of the failed MPL repairs was recommended following detailed orthogonal radiography of the affected limb. Routine preoperative CBD, electrolytes, biochemical profile, and urinalysis were unremarkable. Orthogonal radiography of the left rear limb demonstrated a distal femoral varus angle of 24 degrees and a normal amount of femoral anteversion. Following the removal of all previously placed implants and joint exploration, a distal femoral osteotomy with correction of 17 degrees of distal femoral varus was performed. The resulting distal femoral varus angle measured a normal 7 degrees. The purulent joint fluid was cultured, and grew a methicillin-resistant Staphylococcus pseudintermedius. After culture results and sensitivities, his post-operative antibiotics were changed from cephalexin to Doxycycline.

Xray2: Distal Femoral Osteotomy

5. Discussion:

Patella luxation is a common problem in our canine patients. The underlying problem is almost always related to the malalignment of the quadriceps apparatus. Often times it is also associated with trochlear groove abnormalities or pathology. As a surgeon, it is very important to evaluate each case individually to determine the predisposing causes of the MPL. Kirby had a significant degree of distal femoral varus that could not be corrected by a tibial tuberosity transposition, trochleoplasty, imbrication, or lateral sutures. To correct the underlying abnormality that was responsible for the patella luxation, a distal femoral osteotomy (DFO) was required.

Xray3 Distal Femoral Osteotomy

6. Distal Femoral Osteotomy (DFO):

This modification of the DFO technique was developed at Animal Specialty Group and currently being taught to veterinary surgeons nationally and internationally. The DFO technique utilizes 2 titanium ALPS plates. The advantages to the DFO technique are increased precision, ease of the surgical procedure, minimal morbidity, and a quick recovery and bone healing. It can be performed as an opening or closing wedge osteotomy with radiographic bone healing as early as four to six weeks (closed wedge). Some severe Grade 3 or 4 MPLs with chronic, trochlear groove wear may also be candidates for a trochlear groove prosthesis. This prosthesis was not indicated in Kirby because of the potential for intra-articular sepsis.

7. Recovery:

“Kirby” had a very mild weight bearing lameness at his 2 week suture removal. The osteotomy was healed at 8 weeks post op and the patella remained in the normal position. “Kirby” recovered uneventfully, returning to normal ambulation and activity including hiking and athletics.

by Kirk Wendelburg, DVM
Diplomate American College of Veterinary Surgeons

Animal Specialty Group

DVM, Diplomate American College of Veterinary Surgeons

Dr. Wendelburg is internationally recognized in veterinary orthopedics and is particularly well known for his collaboration in developing today’s most-used canine total hip replacement implants and procedures. He has authored several presentations involving hip replacement and limb biomechanics.