Patient-Specific Rods in Adolescent and Adult Spinal Deformity Surgery: A Narrative Review

Anson G. Bautista; Justin L. Reyes; Nathan J. Lee; Michael W. Fields; Zeeshan M. Sardar; Lawrence G. Lenke; Joseph M. Lombardi; Ronald A. Lehman

doi:10.14444/8642

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Radiological and clinical outcomes of ASD and AIS with patient-specific rod instrumentation.

Study	Design	Sample Size	Major Takeaways
Barton et al10	Retrospective case series	ASD (N = 18)	Reduction in SVA, PT, and PI−LL postoperatively SVA: Preoperative: 96.8 ± 56.8 mm; postoperative: 21.8 ± 37.1 mm (P < 0.001) PT: Preoperative: 32° ± 10.9°; postoperative: 17.7° ± 8.0° (P < 0.0001). PI−LL: Preoperative: 29.2° ± 16.7°; postoperative: −4.1° ± 7.5° (P < 0.001)
Prost et al11	Prospective observational study	ASD (N = 86)	Improvement in sagittal balance at 1-year follow-up in patients with a high preoperative SVA SVA: Preoperative: 53 ± 63 mm; postoperative: 30 ± 41 mm, (P = 0.007) Improvement in PI−LL at 1-year follow-up for patients with a preoperative PI−LL mismatch PI−LL: Preoperative: 15° ± 20°; postoperative: 8° ± 14° (P = 0.006) 18% of patients developed mechanical complications at 1-year follow-up
Prost et al7	Retrospective case series	ASD and AIS Total (N = 77) ASD (N = 43) AIS (N = 24)	Improvement in PI−LL and SVA at 3-month follow-up for ASD patients PI−LL: Preoperative: 20.8° ± 17.8°; postoperative: 8.3° ± 12.8° (P < 0.0001) SVA: Preoperative: 77.3 ± 60.6 mm; postoperative: 41.9 ± 38.0 mm (P < 0.0001) No significant improvements in PT for ASD patients No significant improvements in PI−LL, SVA, and PT for AIS patients
Sadrameli et al12	Retrospective case series	ASD (N = 17)	No significant difference observed between planned SVA and achieved postoperative SVA Significant improvements in PT, SS, LL, and SVA PT: Preoperative: 24.82° ± 9.6°; postoperative: 18.00° ± 8.6° (P < 0.01) SS: Preoperative: 28.65° ± 9.84°; postoperative: 36.53° ± 7.97° (P < 0.01)
Ferrero et al16	Retrospective case series	AIS	Reduction in mean coronal Cobb angle in Lenke Type 1 and Type 2 AIS patients Preoperative: 59° ± 13°; postoperative: 18° ± 11° (P = 0.01) Increase in postoperative thoracic kyphosis Preoperative: 34° ± 14°; postoperative: 45° ± 12° (P = 0.001)
Mayra et al17	Retrospective case series	AIS (N = 61)	Reduction in proximal thoracic, main thoracic, and thoracolumbar curves in AIS patients Proximal thoracic: 30.5° ± 10.2° to 15.6° ± 7.1° (P < 0.001) Main thoracic: 68.5° ± 13.4° to 17.4° ± 9.0° (P < 0.001) Thoracolumbar: 43.4° ± 14.2° to 15.5° ± 9.1° (P < 0.001) Increase in thoracic kyphosis for hypokyphotic patients Preoperative: 8.4° ± 9.5°; postoperative: 22° ± 3.7° (P = 0.0096) Reduction in thoracic kyphosis for hyperkyphotic patients Preoperative: 49.2° ± 7.7°; postoperative: 38.2° ± 9.5° (P = 0.001)
Thomas et al19	Retrospective case series	AIS (N = 48)	Reduction in median coronal thoracic curve at 2-year follow-up Preoperative: 62.7°; postoperative 22.4° (P < 0.001) Increase in median preoperative vs planned thoracic kyphosis Preoperative: 26.5°; planned: 30.1° (P < 0.001)
Faulks et al24	Prospective case series	ASD (N = 20)	Significant improvements in PROs: VAS, ODI, and SF-12 at 6 weeks, 6 months, 12 months, and 24 months postoperatively PSR instrumentation did not reduce junctional complications; however, a decreased rate of PJF was observed from previous studies (5% vs 35%)
Kleck et al25	Retrospective case series	ASD (N = 34)	Improvement in majority difference for SVA, LL, and PI−LL at 2-year follow-up (P < 0.001)
Ou-Yang et al27	Retrospective case series	ASD (N = 57)	Improvement in SVA and PI−LL postoperatively in PSR vs control but not statistically significant
Solla et al28	Prospective case series	ASD (N = 60)	Improvement in PI−LL, decreased mechanical complications, and reduced OR time
Solla et al32	Prospective case series	AIS (N = 37)	Improvement in coronal Cobb angle in patients with a minimum of 1-year follow-up (P = 0.03) Increase in thoracic kyphosis at follow-up Preoperatively: 20°; postoperatively: 35° (P < 0.0001)

Abbreviations: AIS, adolescent idiopathic scoliosis; ASD, adult spinal deformity; ODI, Oswestry Disability Index; OR, operating room; PI−LL, pelvic incidence minus lumbar lordosis; PJF, proximal junctional failure; PRO, patient-reported outcome; PSR, patient-specific rod; PT, pelvic tilt; SF-12, 12-item Short Form Survey; SVA, sagittal vertical axis; VAS, visual analog scale.