Inter-spinous process distance: a novel parameter predicting segmental lordosis during posterior cervical spine...

Area of Science:

• Spine surgery
• Orthopedic research
• Radiographic analysis

Background:

• Assessing spinal alignment is crucial in posterior cervical deformity surgery.
• Inter-spinous process distance (ISPD) is a potential radiographic parameter for evaluating cervical-thoracic alignment.

Purpose of the Study:

• To establish normative values for ISPD in the lower cervical and cervicothoracic spine (C5-T2).
• To investigate correlations between ISPD and patient demographics.
• To determine ISPD cutoff values predictive of segmental lordosis in posterior cervical-thoracic arthrodesis.

Main Methods:

• Dynamic X-rays of 51 patients (153 films) with visible C5-T2 spinous processes were reviewed.
• Radiographic measurements included segmental Cobb angles (S-Cobb) and ISPD.
• Correlations with demographics and predictive cutoff values for lordosis were analyzed using ROC curves and regression models.

Main Results:

• Mean ISPDs ranged from 16.0 mm (C5/6) to 26.0 mm (T1/2).
• ISPD showed weak correlations with age, race, height, weight, and BMI, but significant sex differences at C7/T1 and T1/T2.
• Moderate to strong negative correlations were found between ISPD and S-Cobb (r range: -0.450 to -0.705).
• Cutoff ISPD values for segmental lordosis were <10 mm at C5-6 and <15 mm at C6-T2.

Conclusions:

• ISPD is a simple radiographic parameter that correlates with segmental Cobb angle.
• Vertebral level-specific ISPD cutoff values can help surgeons intraoperatively predict adequate segmental lordosis during posterior cervical deformity surgery.