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Published on: September 16, 2022
Tri-cortical pedicle screw fixation in the most cranial instrumented segment to prevent proximal junctional kyphosis
Zhen Liu1, Ziyang Tang2, Jie Li3
1Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, The Clinical College of Nanjing Medical University, Nanjing, China; Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China.
Background Context:
Proximal junctional kyphosis (PJK) is a common complication of deformity correction for degenerative kyphoscoliosis (DKS) with an incidence between 20% and 40%. Multiple techniques have been proposed to prevent PJK, however, the clinical efficacy of these techniques remains unclear. Here, we investigate the influence of thoracic tri-cortical pedicle screw (TPS) in the most cranial instrumented segment on PJK.
Purpose:
To evaluate the clinical outcomes and mechanical complications in corrective surgery for DKS at a minimum 2-year follow-up using TPS compared to a control group.
Study Design:
Retrospective study.
Patient Sample:
A total of 115 patients with DKS from January 2020 to April 2022.
Outcome Measure:
Patient reported outcome measures included: SRS-22, ODI, VAS scores. Radiographic measures included: Cobb angle, coronal balance distance (CBD), regional kyphosis (RK), and sagittal vertical axis (SVA).
Methods:
Patients were divided into 2 groups: 67 patients in TPS group and 48 patients who with traditional pedicle screws in the most cranial instrumented segment in control group. The radiographic parameters were measured pre-, postoperative period, and at the last follow-up. Complications, including PJK, proximal junctional failure (PJF), and intercostal neuralgia were recorded. PJK was defined as: 10° or higher increase in kyphosis angle which between the inferior endplate of upper instrumented vertebra (UIV) and the superior endplate of the UIV + 2 (PJA). PJF was defined as: fracture of UIV or UIV + 1, need for proximal extension of fusion, or implant failure of UIV.
Results:
There was no significant difference in preoperative radiographic parameters between 2 groups. After surgery, the Cobb angle of the major curve improved significantly in both groups (36.7°±20.4° to 15.3°±11.5° in TPS group, 37.1°±16.0° to 16.8°±9.0° in control group, p<.001). Significant improvements in RK, CBD, and SVA were observed after surgery, and no loss of correction was found during follow-up (p>.05). Patients in both groups had significant improvement in health-relative quality of life (HRQoL) scores, including SRS-22, ODI score (46.5±16.2 to 21.3±13.2 in TPS group; 44.7±18.6 to 23.8±16.4 in control group; p<.05), and VAS (6.5±2.2 to 2.1±1.6 in TPS group; 6.0±2.9 to 2.6±2.0 in control group; p<.05). During the follow-up period, 2 patients in TPS group developed PJK (3.0%), compared to 13 patients in the control group (27.1%) (p<.001). Notably, 5 patients in TPS group developed intercostal neuralgia which was not observed in control group, though all had full recovery following conservative treatment during 3 weeks.
Conclusion:
TPS fixation technique at the most cranial segment can produce satisfactory clinical outcomes in the surgical correction of DKS with a lower risk of PJK. However, it does incur a higher risk for intercostal neuralgia, likely from nerve root irritation from the screw.
Insights
Thoracic tri-cortical pedicle screw (TPS) fixation significantly reduces proximal junctional kyphosis (PJK) in degenerative kyphoscoliosis (DKS) surgery. While effective, TPS may increase the risk of intercostal neuralgia.
Area of Science:
- Spine surgery
- Orthopedics
- Surgical complications
Background:
- Proximal junctional kyphosis (PJK) is a frequent complication after degenerative kyphoscoliosis (DKS) surgery, occurring in 20-40% of cases.
- Existing techniques to prevent PJK have unclear clinical efficacy.
- This study investigates the impact of thoracic tri-cortical pedicle screw (TPS) fixation at the uppermost instrumented segment on PJK incidence.
Purpose of the Study:
- To compare clinical outcomes and mechanical complications between TPS and traditional pedicle screw fixation in DKS corrective surgery.
- To evaluate the efficacy of TPS in preventing PJK at a minimum 2-year follow-up.
Main Methods:
- Retrospective study of 115 DKS patients (January 2020 - April 2022).
- Patients were divided into a TPS group (67) and a control group (48) using traditional pedicle screws.
- Radiographic parameters (Cobb angle, CBD, RK, SVA) and patient-reported outcomes (SRS-22, ODI, VAS) were assessed preoperatively, postoperatively, and at follow-up.
Main Results:
- Both TPS and control groups showed significant improvement in curve correction and patient-reported outcomes.
- The incidence of PJK was significantly lower in the TPS group (3.0%) compared to the control group (27.1%).
- The TPS group experienced a higher rate of intercostal neuralgia (not observed in the control group), with full recovery within 3 weeks.
Conclusions:
- Thoracic tri-cortical pedicle screw fixation at the uppermost instrumented segment is effective in reducing PJK after DKS surgery.
- This technique yields satisfactory clinical outcomes but is associated with an increased risk of intercostal neuralgia.
- Further investigation into managing nerve-related complications associated with TPS fixation is warranted.
