October 7, 2019 at 12:07 pm #96808
How would you manage a delayed low grade deep infection presenting 12 months following T4 to L4 posterior instrumented scoliosis correction and fusion in the case presented below?
Original presentation was a 12 year old with AIS; Risser 0; pre-menarche.
Initial roentgenograph imaging: Lenke 4C: 85° major MT curve, correcting to 55° on side bending; 57° minor TL/L curve, correcting to 35° on side bending.
Operation: T4 to L4 posterior instrumented scoliosis correction and fusion with very good post operative balanced correction.
Post operative course: No concerns. Patient was discharged day 4 post op. No wound concerns. 3 month OPC check doing well.
Patient is now almost 14 years old. No immediate post operative complications following above surgery. Returned for her 12 month post operative out-patient follow-up appointment with a mid-wound swelling that was slightly erythematous. She was otherwise a-symptomatic. She had recently taken a weeks course oral flucloxacillin prescribed by GP for a “superficial wound infection”.
Investigations in clinic:
AP and Lateral whole spine radiographs did not demonstrate concerns with fixation or construct. Patient still skeletally immature (Risser 1). Patient still not started menses.
Bloods showed a slightly low Hb (11.2 microcytic pattern), normal WCC and a CRP of 11.
A MRI scan demonstrated a deep collection that appeared to be related to the right L2 pedicle screw distally which extending superficially to mid-thoracic level. It was superficial at this mid thoracic level. A CT demonstrated all screws to be well fixed but for the right L2. There was evidence of interlaminar fusion but it was not complete. There was no evidence of anterior column fusion at the thoracic apex.October 13, 2019 at 8:41 pm #98613
A difficult situation, and surprisingly common. The published rates of late deep infection following posterior scoliosis surgery ranges from 2.7-7%.
I do not think there is much role for trying to suppress with antibiotics and it may be more effective to treat aggressively as soon as the infection is identified.
Performing wound debridement will allow sampling for MC+S. It is worth considering that the implants may have a biofilm on. They need to be removed or exchanged. In a young patient with remaining growth potential and fusion not complete on CT, removing the implants is likely to result in recurrence of the curve.
Therefore, I would exchange the implants. I would assess whether the wound is clean enough to allow the at the time of the debridement, or whether it should be staged over a few weeks to minimise risk of new implants becoming infected. She would require IV antibiotics post-operatively, then convert to oral once microbiology advice is available. She may require antibiotics for at least 3 months, and potentially more if the CRP is slow to normalise.
Would you consider anterior fusion if it looks particularly contaminated at time of washout, or multiple staged posterior procedures?October 13, 2019 at 9:06 pm #98619
Whilst frustrating these things do happen. The bugs seems to be difficult to isolate too sometimes with pseudomonas etc presenting even later than this.
A colleague had a not too dissimilar case not so long ago – we ended up removing just one side of the construct as there was no discernible tracking to the other side (on pre-op imaging and intra-operative findings). This gave us some comfort around preserving the correction whilst trying to treat the infection.
I agree that biofilms present an issue and that metalwork probably should be removed or replaced but we also know that stability is going to help the eventual fusion and help with treating the infection.
This does also depend on the causative organism – S.Aureus seems to lead to fusion eventually whilst E.Coli does not (a simplification perhaps?)
Do you think you would treat different organisms differently?
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