I think this costruct should be considered "hybrid". There is a lot of sense in using proximal hooks to reduce stress risers at this zone which is typical for all screw constructs. In this respect the construct mentioned differs biomechanically from all screw instrumentations.

Thank you professor Panayot, I agree

I think this construct should be consider as hybrid system . but you have to be cautious  because you may have pull out of the hook due to frscture of TP . especially in caseS of osteoporosis . 

Thank you professor Fadi.We usually use TP hooks in the UIV in the long segment posterior fusion for the treatment of AIS

The pull out problem is something different from adjacent disc damage above and below the instrumented zone. To avoid it, it is necessary to plan the extent of instrumentation and to include in the instrumented zone some more segments (i.e. to go to Th 3 or Th2, where the cervical lordosis begins ).

I tend to agree that this construct has to be treated as a hybrid. 

When used in AIS as described my primary indication is active shoulder balancing; this is besides reducing PJK (hypothetical).

Best Regards

KV

Dear dr Menon,

I was very pleased to have an answer from the wonderful teacher dr Menon. We have met in the AOSpine advanced course in Cairo may 2014.

I have found a paper published in "Spine" which states that "Pedicle screw group must satisfy that pedicle screws consisted more than 80% of anchors implanted"

Pedicle Screw Versus Hybrid Construct Instrumentation in Adolescent Idiopathic Scoliosis • Cao et al

SPINE Volume 39 , Number 13 , pp E800 - E810, 2014

many thanks

 Dear Wael,

I read the paper you mentioned. The draw a line at 80% is really semantic; what it means is that 79% is not hybrid but 81% is !!! My understanding is that it has little relevance in practise

I needed to define the all screw instrumentation for research purpose.

I needed a clear definition to discriminate between the two groups ( hybrid and all screw)

Thank you  Dr Menon

Some years ago we discussed this in the spinal deformity study group

If hooks , or a pedicle/lamina claw is used for one or both the proximal anchors, and all the rest are pedicle screws, I do NOT think it should be listed as a hybrid. 

When a construct is described as a hybrid, i think of pedicle screws distally, and usually in the lumbar spine, and all hooks proximally .One distinction is that the use of hooks in the thoracic spine in a hybrid does not allow axial derotation. a construct with hooks just at the proximal level, but screws elsewhere in the thoracic spine, will still allow deroataion

Many thanks professor King

It must be considered a all-screws construct.

Hybrid instrumentation is related to at least 50% of hooks .

Thank you dr Balsano

https://www.youtube.com/watch?v=eMeYns9e7qg