Recurrence of Local Kyphosis After Percutaneous Kyphoplasty: The Neglected Injury of the Disc–Endplate Complex

Figures & data

Table 1 Characteristics of the Included Patients

	Non-Re-kyphosis Group	Re-kyphosis Group	p value
Age (years)	66.17±8.25	69.06±7.79	0.12
Sex (female)	102 (80.31%)	13 (81.25%)	1.000
BMD (t-score)	−2.87±0.29	−2.92±0.30	0.50
BMI (kg/m^2)	26.06±3.07	25.40±3.27	0.42
Hypertension,Y/N	28/99	2/14	0.58
Diabetes, Y/N	15/112	1/15	0.81
Smoking, Y/N	11/116	0/16	0.47
Alcohol consumption, Y/N	12/115	2/14	1.00
Administration of glucocorticoids, Y/N	14/113	2/14	1.00
Follow-up time (months)	18.39±3.64	17.94±4.95	0.59
Fracture level
T5–T10, L3–L5	26	0
T11–L2	101	16	0.10
Fracture type, wedge fracture Y/N	60/67	6/10	0.46
Disc–endplate complex injury Y/N	29/98	8/8	0.02*
Total cement volume (mL)	5.63±0.61	5.56±0.51	0.81
Cement distribution pattern, solid lump pattern/diffused pattern	20/107	8/8	0.004*
NPEC/PEC	50/77	12/4	0.007*
Vertebral compression rate (%)	68.84±13.69	64.11±12.37	0.19
Vertebral height restoration (%)	13.70±6.82	26.34±11.00	<0.001*
Local kyphosis angle correction (°)	5.01±2.03	9.75±4.00	<0.001*

Note: *Statistical significance was defined as p<0.05.

Abbreviations: BMD, bone mineral density; BMI, body mass index; PEC, PMMA endplate contact; NPEC, non-PMMA endplate contact.

Figure 1 Variation trends of radiographic and clinical indices in both the re-kyphosis and non-re-kyphosis group. Line graphs showing the changes in local kyphosis angle (LKA) (a), vertebral wedge angle (b), anterior intervertebral disc height (c), middle intervertebral disc height (d), posterior intervertebral disc height (e), visual analogue scale (VAS) scores (f) and Oswestry Disability Index (ODI) scores (g) of the two groups at three different time points.

Figure 2 Typical case in the re-kyphosis group. A 67-year-old male patient complained of back pain for 10 days. T1-weighted (a), T2 -weighted (b) and fat-suppressed (c) MRI images showed bone marrow edema signal and disc–endplate complex injury of L1 vertebra(red arrow). Preoperative lateral X-ray image (d) showed multiple degenerative changes of lumbar spine. Lateral X-ray image 1 day after surgery (e) showed the vertebral height was restored and local kyphotic angle was corrected. Lateral X-ray image at the last follow-up (f) showed the occurrence of re-kyphosis.

Table 2 Multivariate Logistic Regression Analysis

Variable	B	Wald	p value	OR (95% CI)
Disc–endplate complex injury	2.86	8.63	0.003	17.46 (2.59–117.69)
Vertebral height restoration (%)	0.14	8.58	0.003	1.15 (1.05–1.26)
Local kyphosis angle correction (°)	0.61	13.29	<0.001	1.84 (1.33–2.55)

Note: B, partial regression coefficient.

Abbreviations: CI, confidence interval; OR, odds ratio.