I presume that the symptoms described in the second sentence presented themselves pre-operatively and not post-operatively. Is this correct? There is no information about the location of the tumour (body of vertebra, lamina itself or soft tissues around it), the method of stabilisation of the spine, the instrumentation used or the stability the spinal column had during or achieved after the operation. Is it necessary for her to be supported with brace or the instrumentation is strong enough to keep the spine in stable position? To answer the question it would be good to have some more information. If the spine is stable and there is no neurological weakness then she can move on the second post-op day. Otherwise the mobilisation will be according the neuro-muscular symptoms the child has.

I think the indication and limitation should be her pain.

As soon as possible after the exudation phase is completed (48-72 hr)

Early functonal mobilisation is the key to a good recovery. Always focusing on the phases of the wound healing process which every good physical therapist needs to know!

I think we have to have further information about location of tumor and stability of the spine before we can answer this question 

If stability is not an issue, she can be made to sit and mobilse on a wheel chair as early as possible. If she has pressure sore, keep her prone in bed and mobilse her after it heals. T11 paraplegics can have community ambulation with calipers.

The description of that case should be more specific, related to the anatomy structures affected from the tumor. In that case,  beyond the operation done for sc decompression , would arise  if it spine stability was affected, if a fixation method was needed, resulting the final stage in which considering that  all previous mentioned was resolved , the answer is asap postoperatively.

 Main issue is whether there is segmental instability or not.If the spine is stabilized with implants, early mobilization is advocated. If not, dynamic X-ray is performed after 4 weeks and after instability is ruled out ,then mobilization is encouraged.

What is the histological diagnosis ? Which structures were affected by the tumour ? What was excised ? Are the interverbral joints intact after surgery ? What is the postoperative course of the neurologic deficit ? Perhaps there are some more questions related to this case in order to give a reasonable answer.    

All these questions are asked before from more that one responder, as there is no clear picture on post-operative neurology, but there was no feedback.

Pro domo sua, the most important issue is the histology. Nobody asked about it before.  There is only mentioning of a benign tumor. This is important but insufficient. For example, there is a big difference between osteoid-osteoma and aggressive osteoblastoma. Or between osteolytic aneurysmal cyst and osteochondroma.  

Thanks for all responses. The patient's neuro-musculoskeletal assessment findings and MRI were used as guide for the progression of the  patient. Thoraco-lumbar brace was used to support trunk stability initially. With appropriate trunk/lower limbs therapeutic and secondary disability prevention programmes, The patient commenced ambulatory training about 3week into rehab AND WAS GRADUALLY PROGRESSED. This is about the 10th week; she could ambulate unaided with good gait. she is due for discharge in 2-weeks time. Great recovery!

In general as soon as possible is the answer.  There is a trophic effect of nerve on muscle and deconditioning starts quickly.  Within the limits of wound healing and stability, early mobilization and therapy is best.