Surgical Correction of a femoral cervical fracture in a golden retriever puppy

         A three month old male golden retriever was presented with the complaint of sudden non weight bearing lameness on the right hind limb after jumping off a chair. Physical examination revealed crepitus and pain on abduction of right hip joint. Swelling and pain was noticed at the right stifle joint. 

        

         Radiograph of Ventro-dorsal view of the hip revealed a Cervical fracture and an oblique incomplete distal metaphyseal fracture of the right femur. The radiolucent line noted on the distal end of the femur can be mistaken for normal physeal growth plate in puppies. This was confirmed as an incomplete fracture by comparing the radiograph with that of the contralateral limb and correlating with physical examination findings. Anatomical reduction and stabilization was planned through surgery for the femoral neck fracture and immobilizing the right femur was planned post surgery was deemed enough for the purpose of stabilizing the distal metaphyseal fracture. 

            A standard dorsal cranio-lateral approach was chosen for surgical correction. Two K-wires of 1.8mm were inserted normograde under C-arm guidance after blunt dissection of tensor fascia lata, biceps femoris and superficial gluteal muscles. The fracture site could not be visualized as it was on the medial surface of the femur. Pins were drilled blindly under C-arm guidance. The wound was closed in a routine manner and an Ehmer’s Sling was applied for 2 weeks.           

          

   

Intraoperative fluoroscopic images of normograde pinning  

Ventrodorsal Oblique radiograph after completion of surgery showing the two parallelly placed K-wires

3 weeks post-operative radiograph

6 weeks post-operative radiograph

  Swimming was advised after 15 days as the owner had access to a pool nearby. The dog was presented for review only 3 weeks post surgery. Radiograph of VD view of Hip revealed a hazy fracture line, periosteal reaction, bridging soft callus suggestive of early bone remodeling. Migration of the K-wires was evident but there were no overt clinical signs because of that. Clinically, weight bearing was noticed on the affected limb although a slight cow-hock stance was noted. 

    

 Discussion

1) Femoral neck fractures are commonly seen in dogs and cats younger than 1 year of age. Because of considerable bending moments generated within the femoral neck, conservative treatment of these fractures routinely results in the formation of a hypertrophic pseudoarthrosis, with subsequent decreased range of motion and persistent lameness. Anatomic reduction and stabilization is thus warranted. 

2) Cervical fractures are more difficult to treat because of the lack of intrinsic stability, lack of visualization of the fracture site and the presence of substantial bending moments. The magnitude of these disruptive forces depends on the angle of the fracture line with respect to the long axis of the femoral neck. Shear stresses at the fracture are minimal when the fracture plane is 30 degrees or less to the horizontal. However, steeper fracture lines (>30 degrees) to the horizontal result in greater shear forces and are potentially associated with a greater incidence of nonunion. 

    

        

Radiographs showing different femoral neck fracture planes. Cervical fractures with

steeper angles are associated with greater risk of postoperative instability than those with shallower
angles. 

 

                                         

                Radiographs from the present case showing a steep femoral neck fracture plane angle (70 degree)

3) Although Kirschner wires, small-diameter Steinmann pins, and bone screws can all be used for repair, use of multiple pins, rather than lag screws, is recommended in immature patients to prevent premature physeal closure because the capital physis is often engaged when cervical fractures are repaired. On the other hand, lag screws are preferred in mature and giant breeds of dogs as they provide more strength.

4) The blood supply to the proximal femur is a complex arterial network that can be subdivided into (1) extraosseous, (2) intracapsular, and (3) intraosseous vessels. They include Lateral and Medial circumflex iliac arteries, cranial and caudal gluteal arteries and the ilio-lumbar arteries.  Because all these branches of arteries propagate from the extraosseous vessels via a single extracapsular vascular ring, the blood supply to the femoral neck and head is highly susceptible to vascular insult during  fracture occurence and during surgical repair. This sequelae to this can be ‘apple coring’ appearance of the femoral head, premature physeal closure, femoral head necrosis and osteoarthritis. 

        In the present case, although the fracture healing was uncomplicated despite the migration of pins, coxo-femoral incongruity was noticed on one of the post-operative radiographs. The dog is likely to develop osteoarthritis earlier in life but at present, very satisfying to see him trot around in excitement like a typical golden retriever puppy should be at his age.