MMP ─ a new alternative for TTA planning

April 14, 2015

Orthofoam MMP, a novel TTA methodology developed by Orthomed features a new concept of TTA planning, which has the remarkable advantege of using the tibia only.
The degree of advancement of the tibial tuberosity is calculated on a standard medio-lateral radiograph of the tibia.

The detailed description of Orthofoam MMP method is available in pdf format through this link.

http://www.google.hu/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CC8QFjAC&url=http%3A%2F%2Fwww.orthomed.co.uk%2Fdownload%2F%3Ff%3D20121105104816_orthofoam_mmp_english_web.pdf&ei=SUIkVdXIJ-n_ygOj1IDoAg&usg=AFQjCNF5JBmP_sij5pRhtVCqGCIdQtlJKg&sig2=OlvO0uC3733Q4M-I4jWZmg&bvm=bv.89947451,d.bGQ

The MMP type planning of TTA consists of the following steps.

1. The tibial plateau is drawn first (blue), followed by the mechanical axis of the tibia (green), resulting in a line connecting the intercondylar eminences and the center of the talus. This is analogous to the first step of TPLO planning.

2. Next, a line is drawn from the tibial insertion site of the patellar tendon (TT) at a right angle to the tibial mechanical axis (yellow).

3. From the TT point, another line running in 45 degrees caudoproximally to the previous one is drawn (pink).

4. At the intersection of the previous line (pink) and that of the tibial plateau (blue), a new line is drawn perpendicularly to the tibial plateau (orange). The distance between this line and the TT point at the level of the line perpendicular to the mechanical axis of the tibia (yellow) is the adequate measure of advancement, i.e. the size of the cage to be used.

The MMP planning method is simple, requiring a single well positioned medio-lateral radiograph only, without concerns for stifle angulation or femoral positional errors. A disadvantage, however, is that in the case of an extremely large inclination of the tibial plateau the degree of advancement may be underestimated and vice versa. In our experience with the method this far, calculation results coincide well with those of the more established common tangent (CT) method at the average 21-to 24-degree range of angulation of the tibial plateau (i.e. the majority of the clinical cases).

Orthomed has released an informative table reflecting cage sizes of choice based on clinical experience with MMP planning to date.

Cage size

 

Small Breed

 

Standard Breed

Chihuahua / Yorkshire Terrier
3mm

Springer Spaniel / Small Border Collie / Staffordshire Bull Terrier / Weimoraner

7.5mm

West Highland Terrier / Jack Russell / Tibetan Terrier / Fox Terrier
5mm

Labrador Retriever / Boxer / Small Rottweiler / Standard Poodle / American Bulldog / Doberman / Britanny

9mm

Cavalier King Charles Spaniel
6mm

Malamute
10.5mm or 12mm

 

Staffordshire Bull Terrier / Small Cocker Spaniel / English Bulldog / Beagle
7mm

8mm (also English Bulldog and Beagle)

Large Rottweiler / GSD / Newfoundland /Bull Mastiff / Dogue de Bordeaux / other giant breeds

12mm with double staple

 

 

It is to note however, that the desired degree of tibial tuberosity advancement varies by the individual.
When in doubt, round up to a larger cage size.