Journal of Neurosurgery: Spine 2026;45(4):516-526
Combined sagittal and coronal malalignment poses a particular challenge in adult spinal deformity surgery because correction must address both planes without concentrating excessive forces on individual fixation points. Vila and colleagues investigate the side-to-side domino connector as an active correction tool rather than simply a device for linking rods. Their multicenter cohort associates its use with greater correction and better maintained sagittal alignment at two years. However, comparable patient-reported outcomes and a higher rate of rod breakage/pseudarthrosis require a balanced interpretation: improved radiographic correction does not, by itself, establish greater clinical benefit or mechanical safety.
Objective
To compare radiographic correction, complications and patient-reported outcomes after adult spinal deformity surgery with or without a side-to-side domino connector used for correction of combined sagittal and coronal malalignment.
Methods
This retrospective analysis used a prospectively collected database from six European centers. It included 224 patients undergoing instrumented fusion to the pelvis with at least two years of follow-up: 81 with a domino connector and 143 without. Eligibility required a C7-to-central sacral vertical line distance greater than 20 mm together with sagittal malalignment defined by at least one of the study’s pelvic tilt, sagittal vertical axis, thoracic kyphosis or global tilt criteria.
Connector use was selected by the surgeon, often for more severe, rigid deformities. The connector group started with worse biplanar malalignment and underwent pedicle subtraction osteotomy more frequently. Propensity matching produced 69 pairs based on baseline global tilt, coronal displacement, osteotomy use and rod number. A separate analysis compared patients without pedicle subtraction osteotomy. Outcomes included standing radiographs, mechanical and neurological complications, unplanned reoperations, Oswestry Disability Index and Scoliosis Research Society-22 scores.
Main results
In the matched cohort, two-year global tilt was 24.6° with connectors versus 33.1° without, and L1-S1 lordosis was 54.8° versus 49.0°. Final coronal displacement did not differ significantly. In the full cohort, mechanical complications occurred in 41.9% of both groups, but the combined rod-breakage/pseudarthrosis category was higher with connectors: 22.2% versus 9.1% (P=.006). Unplanned reoperation rates were 27.2% versus 34.3%, without a significant difference. Two-year ODI and SRS-22 scores were comparable. Greater lumbar lordosis also persisted in the subgroup without pedicle subtraction osteotomy, although that comparison retained baseline imbalances.
Interpretation
The technical distinction is the intended force direction, referenced to trunk shift rather than simply curve concavity. For distraction-based correction, the authors place the connector on the side of coronal malalignment; for compression during asymmetric osteotomy closure, they place it opposite the shift. Their illustrated sequence establishes lumbopelvic fixation and initial correction through a contoured contralateral rod before connector-assisted adjustment. Intraoperative imaging checks coronal alignment against a pelvic reference. This is a useful framework for planning correction, but force distribution is a proposed mechanical rationale, not proof that the connector independently prevents fixation failure.
Limitations
This was not a randomized comparison, and matching cannot eliminate unmeasured confounding. Deformity rigidity, surgeon preferences, center-specific practice and the heterogeneity of control constructs may affect both correction and complications. Matching addressed selected variables rather than every baseline difference; thoracic kyphosis remained different between matched groups. The subgroup without pedicle subtraction osteotomy likewise does not isolate the device’s intrinsic effect from other corrective maneuvers.
The clearest persistent radiographic advantage was sagittal. Greater correction from a more displaced starting position should not be confused with significantly better final coronal balance. Similarly, comparable ODI and SRS-22 scores do not establish equivalence, but they do mean that superior patient-reported benefit was not demonstrated at two years.
An identical aggregate mechanical complication rate does not neutralize the higher rod-breakage/pseudarthrosis rate. Greater deformity severity and osteotomy use may contribute, but this study cannot establish their causal contribution or exclude a device-related contribution. The absence of reported intraoperative implant complications is also insufficient to establish general safety. The study received industry funding, and several authors disclosed relevant financial relationships. Longer follow-up and prospective comparative evaluation are needed to clarify durability and clinical benefit.
Clinical takeaway
A domino connector can be considered a correction adjunct when managing complex biplanar adult deformity, with its placement determined by the planned compression or distraction mechanism. This study supports its corrective potential, not routine use in every construct, replacement of an indicated osteotomy, or an expectation of better functional outcomes. Planning should retain equal attention to alignment, the lumbopelvic foundation and subsequent mechanical failure risk.