{"title":"Patient-Specific 3D-Printed Reference Rod for \"Smiley Face Rod\" Repair of Lumbar Spondylolysis in a Patient with High Body Mass Index.","authors":"Takayuki Kitahara, Masatoshi Morimoto, Naoto Ono, Takafumi Ohshima, Yuji Nagao, Saori Soeda, Daiki Nakajima, Makoto Takeuchi, Hiroshi Kageyama, Junzo Fujitani, Hiroaki Manabe, Fumitake Tezuka, Koichi Sairyo","doi":"10.22603/ssrr.2025-0418","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>The \"Smiley Face Rod\" (SFR) method is an effective direct repair technique for lumbar spondylolysis. However, three-dimensional rod contouring is technically demanding, particularly in patients with a high body mass index (BMI), where deep soft tissue obscures anatomical landmarks.</p><p><strong>Technical note: </strong>We report a technique using a patient-specific three-dimensional (3D)-printed model to create a sterilized \"Reference Rod\" template. A 27-year-old male with bilateral L5 spondylolysis and severe obesity (BMI 39.8 kg/m<sup>2</sup>) underwent SFR repair. A 3D model was printed from preoperative computed tomography data. A malleable template rod was contoured on this model to perfectly fit the lamina and spinous process and then sterilized. Intraoperatively, the final titanium rod was bent to match this sterile Reference Rod. This allowed for a \"one-pass\" insertion through the interspinous ligament with optimal bony contact, eliminating intraoperative trial-and-error.</p><p><strong>Conclusions: </strong>The 3D-printed Reference Rod technique is a feasible approach that may facilitate rod contouring for SFR in challenging high-BMI cases by providing a tangible template to address the visualization and geometric limitations of conventional fluoroscopy.</p>","PeriodicalId":22253,"journal":{"name":"Spine Surgery and Related Research","volume":"10 3","pages":"511-515"},"PeriodicalIF":1.6000,"publicationDate":"2026-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13255105/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Spine Surgery and Related Research","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.22603/ssrr.2025-0418","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/5/27 0:00:00","PubModel":"eCollection","JCR":"Q3","JCRName":"SURGERY","Score":null,"Total":0}
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Abstract
Introduction: The "Smiley Face Rod" (SFR) method is an effective direct repair technique for lumbar spondylolysis. However, three-dimensional rod contouring is technically demanding, particularly in patients with a high body mass index (BMI), where deep soft tissue obscures anatomical landmarks.
Technical note: We report a technique using a patient-specific three-dimensional (3D)-printed model to create a sterilized "Reference Rod" template. A 27-year-old male with bilateral L5 spondylolysis and severe obesity (BMI 39.8 kg/m2) underwent SFR repair. A 3D model was printed from preoperative computed tomography data. A malleable template rod was contoured on this model to perfectly fit the lamina and spinous process and then sterilized. Intraoperatively, the final titanium rod was bent to match this sterile Reference Rod. This allowed for a "one-pass" insertion through the interspinous ligament with optimal bony contact, eliminating intraoperative trial-and-error.
Conclusions: The 3D-printed Reference Rod technique is a feasible approach that may facilitate rod contouring for SFR in challenging high-BMI cases by providing a tangible template to address the visualization and geometric limitations of conventional fluoroscopy.
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