Correlations between the inflection point and spinal sagittal alignment in asymptomatic adults

Area of Science:

• Orthopedics
• Radiology
• Biomechanical Engineering

Background:

• Spinal sagittal alignment is crucial for maintaining posture and function.
• Understanding the relationships between different spinal parameters is essential for diagnosing and treating spinal deformities.
• The inflection point (IP) is a key parameter in assessing spinal alignment.

Purpose of the Study:

• To analyze correlations between the inflection point (IP) and various spinal sagittal parameters in asymptomatic adults.
• To establish linear regression models for predicting spinal sagittal parameters based on the IP.
• To provide insights into the regulatory mechanisms of spinal sagittal alignment.

Main Methods:

• Recruited 205 asymptomatic adults (age > 18 years).
• Collected full-spine, standing X-rays.
• Measured: IP, thoracic kyphosis apex (TKA), lumbar lordosis apex (LLA), distances from apex to gravity line (TAPL, LAPL), thoracic kyphosis (TK), lumbar lordosis (LL), and lumbar lordosis arcs (LLUA, LLLA).

Main Results:

• The IP showed significant correlations with age, TKA, TAPL, TK, LLA, LAPL, LLUA, and LLLA (p < 0.05).
• The IP was not significantly correlated with LL.
• Significant relationships were also found between thoracic and lumbar parameters (TKA-LLA, TAPL-LAPL, TK-LL, TK-LLUA, TK-LLLA).

Conclusions:

• The inflection point (IP) is significantly related to spinal sagittal alignment in asymptomatic adults.
• Developed predictive formulas for sagittal parameters using the IP.
• These findings assist surgeons in understanding spinal alignment regulation and planning therapeutic strategies.