Premature Closure of Distal Physis



  Premature Closure of the Distal Physis is an orthopedic deformity of the forelimb.



     Premature Closure of the Distal Physis occurs in immature dogs with open physes (growth plates). Severe deformities can cause elbow luxation or subluxation. An affected dog will show signs of intermittent lameness with varying degrees. Often, the limb is deformed by moderate bowing, noticed in certain breeds of dog.


    The growth plates are responsible for bone growth in immature dogs, until the growth plates close around one year of age. The growth plates are located at the end of each bone, and immature (open) growth plates are softer than mature bones., which are more susceptible to injury. The distal (towards the bottom of the bone) growth plate is responsible for 90% of the entire bone’s growth.


    Chondrodystrophic (dogs with angular limb deformities) breeds, such as the Basset Hound, Pekingese, Bulldog, develop PCDP (premature closure of distal physis), which is caused by asynchronous growth of the radius and ulna without apparent injury to the growth plate. Therefore, meaning that the growth plate closes prematurely and causes the Ulna to stop growing while the Radius continues to grow (lengthen). This abnormal growth results in incongruity (unevenness) of the elbow joint because either the radius or ulna is inappropriately, abnormally short in comparison to the other bone. The incongruity causes the Radius to bow moderately. Additionally, the wrist twists and the elbow joint is forced to luxate. This is why the deformity is often called Elbow Dysplasia.


    Studies have shown that these are inherited monogenic (singular) traits that cause the deformities. Dogs exhibiting these deformities should be withheld from breeding.


    This orthopedic issue must be resolved while the bone still has a lot more growing to do, the sooner the better, usually before the pet is 8 months of age. Surgical correction consists of either ulnar lengthening or ulnar shortening, but Ulnar Lengthening is way more common. Ulnar Osteotomy (cut only) or Ulna Ostectomy (removal of small portion) is the surgical procedure required to lengthen the Ulna. A small portion of the Ulna is either cut or removed, either secured with or without an IM pin, and immobilized for 6-8 weeks via bandage or K-E apparatus. This cutting or removal of [part of the Ulna, releases the pressure on the Ulna from the Radius and allows elbow congruity.


(Shorter) Ulna

(Bowed) Radius

Humerus

Osteophytes (arthritis)

Carpus (wrist)

Elbow

Ligaments in White



Ulna Osteotomy with IM Pin

Ulna Ostectomy without IM Pin