Well, surgery it was.

We visited Dr. LeeAnn Blackford this AM. Nina was diagnosed with a luxation of the superior digital flexor tendon.

• This is an uncommon injury usually seen in the Sheltie, but can occur in any breed.
  
• The superficial digital flexor tendon is the caudal-most component of the calcanean (or Achilles) tendon.
  
• Its retinaculum holds it on the caudal aspect of the tuber calcanei.
  
• When this retinaculum tears, usually due to exercise-related trauma, the tendon can luxate medially or laterally.

What does all that mean? Well, a little canine anatomy first. Take the rear right leg ... Focus of the purple tendon:

The Achilles' tendon is on the back side of the leg. It consists of two major and three minor tendons.

(1) Gastrocnemeus tendon - the main tendon that attaches to the heel (or calcaneous bone)

(2) Superficial digital flexor - second main tendon that partially attaches to the calcaneous bone and then passes over the end of the heel bone and attaches to the digits; this tendon flexes the digits.

Three minor tendons (not shown)

The detailed diagram below shows that bursa cushions the purple tendon (superior digital flexor) where it runs over the heel bone (tuber calsis). This is the bursa that has been so swollen on Nina during the last few weeks.


Now we need to review the definitions of a few terms....

retinaculum [ret″ĭ-nak´u-lum] - a structure or that retains an organ or tissue in place. In this case the retinaculum has been described as a sheath covering the tendon.

luxation - [luksā′shən] a dislocation or a displacement.


So, in plain English, Nina's Achilles tendon was dislocated off the heel bone due to a torn sheath that holds the tendon in place.

The surgery was performed to repair the torn sheath to stabilize the dislocation.


The following three diagrams show how the surgery that was performed on Menina this morning.