Dr. Nathaniel Toop’s lecture “Three-Column Osteotomy Cases” is a rich, case-based tour through the full Schwab 3–6 spectrum of three-column osteotomies, showing when they are still indispensable despite modern alternatives and how much correction they can realistically achieve.
Framing and indications
- standard tools (Schwab grade 1–2 osteotomies plus interbodies, lateral approaches, expandable cages) often suffice for mobile curves, but fixed, severe deformities or extreme PI–LL mismatch may still require three-column osteotomies despite their well-documented morbidity.
Schwab grade 3: classic and variant PSOs
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A typical lumbar PSO is shown in a 51‑year‑old woman with prior L3–S1 fusion, flatback (PI 81°, LL 34°, SVA ~30 cm); a T10–pelvis construct plus L4 PSO yields ~31° of lordotic gain and brings SVA to ~10 cm with age-adjusted PI–LL mismatch.
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Discussion touches on ALIF vs all‑posterior strategy, use of BMP to reduce mechanical failures, and the importance of multiple rods across PSO levels; Toop and colleagues typically aim for four rods, sometimes leaving deep “closing” rods plus main rods on top.
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A sacral (S1) PSO in a young woman with PI > 100° illustrates PI-lowering osteotomy: by cutting through the sacrum and sacroiliac region and closing the wedge, PI drops to ~77° and PI–LL mismatch improves, with accepted residual grade 2 L5/S1 spondylolisthesis but good clinical outcome.
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A high thoracic PSO (T3) in a drop‑head patient with long T3–pelvis fusion demonstrates cervical–thoracic realignment; biventor traction (two ropes, one horizontal, one angled ceilingward) helps close the osteotomy and regain horizontal gaze without over- or under-correcting.
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An asymmetric PSO is used in a woman with massive coronal and sagittal deformity after prior Harrington rod removal and a continuous fusion mass; one large asymmetric wedge simultaneously improves a 78° lumbar curve and flatback, bringing coronal balance from 27 cm to ~6 cm and PI–LL to ~0°.
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A vertebral column shortening osteotomy (technically a PSO variant) at T12 for tethered cord illustrates a “neutral” PSO: about 1.5–2 cm of body is removed in a parallel fashion to shorten the column without changing global alignment, preserving the patient’s already-normal sagittal profile.
Schwab grade 4: extended PSOs
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Extended PSO (wedge plus disc above) is reserved for cases where a standard PSO cannot provide enough correction, effectively adding another 10–15° by incorporating the cranial disc.
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One case: a woman with prior L1–S1 fusion, PI 44°, LL 6°, SVA ~14 cm and thoracic hypokyphosis; an L4 extended PSO within a T4–pelvis construct yields LL 45° (PI–LL mismatch ~1°) and SVA ~4 cm, with five rods across the osteotomy (deep short rods, main rods, and an accessory/satellite rod).
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Another case combines extended PSO with adjacent level failure and L3–4 grade 2 spondylolisthesis after prior L4–S1 fusion; an L4 extended PSO integrates reduction of the spondylolisthesis and correction of PI–LL mismatch to ~10°, while also improving pelvic tilt and SVA.
Schwab grade 5: single-level VCRs
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Vertebral column resection (VCR) is shown for a man with prior thoracolumbar Harrington instrumentation and double major curves (thoracic ~59°, lumbar ~55°) where the thoracic curve is fixed.
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A T7 VCR (with a Harm’s cage) plus lumbar SPOs in a T2–pelvis construct reduces the thoracic curve to ~29° and lumbar to ~32°, while keeping sagittal parameters in or near normal ranges (PI–LL around −10°, balanced PT and SVA).
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Another VCR case: a woman after T11–L1 carbon-fiber fusion for burst fracture develops a 75° kyphosis at T10–L1; a T12 VCR within T2–L4 fixation initially corrects to ~16°, but she suffers distal junctional failure at L4 almost immediately, requiring extension to the pelvis; final films show T10–L1 kyphosis ~16°, normalized PT and SVA slightly negative.
Schwab grade 6: multi-level VCR
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The final and most complex case is a 60‑year‑old woman with a remote traumatic T7–8 fracture treated non‑operatively in adolescence, now with a fixed ~91° T7–8 kyphotic spondyloptosis (essentially a right angle) and compensatory hyperlordosis (LL 81°, PI 56°, PT 16°, TK 84°).
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A T2–L2 construct with two-level VCR (T7 and T8) and four rods across the resection corrects thoracic kyphosis to ~57°, reduces lordosis to ~59° (PI–LL ~3°), and maintains reasonable SVA (~8 cm), eliminating the spondyloptosis; Toop describes it as the hardest case of his training, but with an excellent radiographic and clinical result.
Overall messages
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Three-column osteotomies are being used less frequently because lateral approaches, expandable cages, age-adjusted targets, and PSRs can often avoid them, but they remain essential for severe, fixed deformities and high PI–LL mismatches that are unreachable by lesser means.
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Key technical themes across cases include: careful choice of level and type of osteotomy, liberal use of multi‑rod constructs, use of BMP where available, and aggressive planning to protect junctions (e.g., going higher into the thoracic spine in hypokyphotic patients).