10 - Mega Foreign Body Granuloma after using the Universal ClampTM for Adol...

#10 Mega Foreign Body Granuloma after using the Universal ClampTM for Adolescent Idiopathic Scoliosis. What Is it and Can it Be Prevented?

Pediatric Spine

Poster Presented by: J.W. Duncan

Author(s):

J.W. Duncan (1)
R.A. Bailey (2)
A.T. Tran (3)
J.L. Abraham (4)

(1) University of Southern California, Keck School of Medicine, Department of Orthopaedic Surgery, Los Angeles, CA, United States
(2) Californa Spine, Clinical Research, Los Angeles, CA, United States
(3) White Memorial Medical Center, Department of Plastic and Reconstructive Surgery, Los Angeles, CA, United States
(4) State University of New York (SUNY) Upstate Medical University, Department of Pathology, Syracuse, NY, United States

Abstract

Purpose of the Study: To characterize the postoperative course and histopathologic analysis of the peri-implant tissue of 2 pediatric patients with Adolescent Idiopathic Scoliosis (AIS) who suffered the postoperative development of an aseptic soft tissue reaction, resulting in mega granulomas which were adjacent to sites of sublaminar polyethylene terephthalate (PET) straps used in Zimmer's Universal ClampTM(UC) (Zimmer Spine, SAS, Bordeaux, France) spinal fixation system 8 months following posterior spinal surgery for AIS correction. We coin the term "mega granuloma" because of the extensive mass of granulation tissue with multiple breaks through the skin and because they extended above and below the lamina.

Methods: Sixty consecutive patients underwent spinal deformity correction that utilized posterior instrumentation surgery for scoliosis in a senior spine surgeon's practice between 2008 and 2010 were reviewed for implant related postoperative complications. We characterized the postoperative course and histopathologic analysis of the peri-implant tissue of 2 pediatric patients who developed mega granulomas 8 months postoperative which were adjacent to sites of sublaminar PET straps used in the UC spinal fixation system. Histologic examination of the peri-implant tissue was performed as well as a literature review regarding the safety and biocompatibility of PET implants in spine surgery. The implant related complication rate of scoliosis patients whose correction procedure utilized the UC are compared to the Scoliosis Research Society┬┤s(SRS) Morbidity & Mortality (M&M) database complication rates for adult and pediatric patients, which are 1.6% & 1.5%, respectively.

Results: Histopathology revealed benign soft tissue with extensive granulation tissue, acute and chronic inflammation and fibrosis and histiocytes, foreign body giant cell reaction, including histiocytes with engulfed bifringent polyethylene (PE) particles/debris with bifringent PE particles also lying freely in the tissue.

Sixty consecutive patients underwent scoliosis correction surgery, only the 2 above-mentioned UC implant related complications occurred, with a resultant complication rate of 3.3%, which is over twice as high as the SRS M&M deep wound & implant related complications rates. Twenty-six of these patients utilized the UC fixation system, with that cohort as a denominator; the implant related complication rate is 7.7%, which is almost 5 times as high as the SRS M&M database rates.

Conclusion: The sublaminar PET band component of the UC, is subject to micromotion, likely secondary to loosening, which generates polyethylene debris particles, that set in motion the cascade of a foreign body reaction, with acute and chronic inflammatory cells, the result being mega granuloma formation.

Close surveillance should be maintained in patients with AIS who utilize the UC construct because of the possible early development of granuloma.

Granulomas

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