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

BACKGROUND: Recurrent of local kyphosis after percutaneous kyphoplasty (PKP) is rarely reported and discussed. Literatures reported that re-kyphosis is usually a consequence of refractures of augmented or adjacent vertebra. However, whether re-kyphosis should be considered as a complication of refractures and has an impact on clinical efficacy of PKP during follow-up time is unknown. The purpose of this study is to evaluate the related risk factors and clinical significance of the recurrent of local kyphosis in osteoporotic vertebral fracture (OVF) patients without refractures. PATIENTS AND METHODS: A total of 143 patients who underwent single-level PKP were recruited and assigned into the re-kyphosis group and non-re-kyphosis group. Clinical and radiographic data were collected and compared between the two groups. Then, multivariate logistic regression analyses were conducted to identify the related risk factors. RESULTS: During follow-up, 16 of the 143 patients presented postoperative re-kyphosis. The average local kyphosis angle increased from 11.81±8.60° postoperatively to 25.13±8.91° at the final follow-up which showed a statistically significant difference (p<0.05). Both groups had significant improvements in postoperative visual analogue scale (VAS) and Oswestry Disability Index (ODI) scores compared to their preoperative values (p<0.05). However, in the re-kyphosis group at final follow-up, the VAS and ODI scores showed worsening compared to the postoperative scores. Logistic regression analysis showed that disc–endplate complex injury (OR=17.46, p=0.003); local kyphosis angle correction (OR=1.84, p<0.001); and vertebral height restoration (OR=1.15, p=0.003) were risk factors for re-kyphosis. CONCLUSION: Re-kyphosis is not rare in patients with osteoporotic vertebral fracture and tends to have an inferior prognosis following PKP surgery. Patients with disc–endplate complex injury and more correction of vertebral height and kyphosis angle are at a higher risk for re-kyphosis after PKP surgery than others.