Preoperative Cobb angle-guided surgical decision-making between percutaneous kyphoplasty and short-segment fixation with vertebroplasty in stage III Kümmell disease without neurological deficits: a two-center retrospective study.

OBJECTIVE

To compare the clinical and radiographic outcomes of percutaneous kyphoplasty (PKP) and short-segment fixation with vertebroplasty (SSF+VP) in patients with stage III Kümmell disease (KD) without neurological deficits, and to evaluate whether the preoperative local Cobb angle can guide risk stratification for surgical decision-making.

METHODS

This two-center retrospective study included 117 patients with stage III KD without neurological deficits who underwent surgery between January 2019 and December 2024. Among them, 71 underwent PKP and 46 underwent SSF+VP. Perioperative parameters, VAS, ODI, local Cobb angle, Cobb angle loss, cement distribution, and cement leakage were compared. In this exploratory analysis, residual mild pain was defined as a final follow-up VAS ≥2. In the PKP group, the association between Cobb angle loss and final follow-up VAS was analyzed. ROC analysis was performed to assess the predictive value of the preoperative Cobb angle for residual mild pain after PKP. Patients were further stratified according to the optimal preoperative Cobb angle cut-off, and 2,000 bootstrap resamples were used for internal validation.

RESULTS

Baseline characteristics were comparable. PKP was associated with shorter operative time, less blood loss, smaller cement volume, shorter hospital stay, and greater early VAS and ODI improvement than SSF+VP. However, at final follow-up, SSF+VP showed lower VAS, while ODI was comparable. Radiographically, SSF+VP achieved lower postoperative and final Cobb angles, less Cobb angle loss, more diffuse cement distribution, and less cement leakage. In the PKP group, Cobb angle loss correlated positively with final VAS (rho=0.542, p < 0.001). The preoperative Cobb angle predicted residual pain after PKP, with an optimal cut-off of 25.95°. After stratification, final VAS did not differ between procedures in the mild-moderate kyphosis subgroup, whereas SSF+VP showed better intermediate-term pain outcomes in the severe kyphosis subgroup. Bootstrap validation supported the stability of this risk-stratified finding.

CONCLUSION

Both PKP and SSF+VP improved pain and function in stage III KD without neurological deficits. PKP enabled faster early recovery, whereas SSF+VP provided better correction maintenance and intermediate-term pain outcomes in patients with severe preoperative kyphosis. Preoperative Cobb angle-based stratification may help guide individualized surgical selection.