158 - Lumbopelvic Sagittal Alignment in Patients with Sacroiliac Joint Pain...

#158 Lumbopelvic Sagittal Alignment in Patients with Sacroiliac Joint Pain after Posterior Lumbar Interbody Fusion

Oral Posters: Deformity

Presented by: J. Hur


J.-W. Hur (1)
C.-K. Park (1)
K.-S. Ryu (1)
J.-S. Kim (1)
M.-H. Shin (1)

(1) Seoul St. Mary's Hospital, Neurosurgery, Spine Center, Seoul, Korea, Republic of


Purpose: The purpose of this retrospective cohort study was to elucidate the role of changes of lumbopelvic sagittal alignment in the pathogenesis of sacroiliac joint pain (SIJP) after posterior lumbar interbody fusion (PLIF) by comparing these changes with the control, patients without SIJP.

Materials and Methods: Authors recruited 40 patients who had underwent PLIF consecutively between June 2009 and December 2011, and divided them into two groups: SIJP group, 20 patients who had SIJP postoperatively and experienced the pain relief after SIJ block; Non-SIJP group, 20 patients who underwent PLIF without postoperative SIJP. All patients underwent PLIF by a single surgeon. The patients were assessed various clinical and peri-operative radiologic parameters including age, sex, diagnosis, BMD, BMI, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). Based on these parameters, target LL (LI + 9°), achieved rate of LL (postop LL/target LL *100) (LI ± 9°), ratios among each pelvic parameter (PT/PI, SS/PI, PT/SS) and LL-PI relationship (LL-PI mismatch (Δ)) were calculated and compared between two groups. Student t-test was performed to compare the mean value of clinical and preoperative radiologic parameters and correlations between pelvic incidence and postoperative lumbar lordosis in each group were determined using the Spearman coefficient.

Results: There were no significant differences in the patient's demographics and preoperative lumbopelvic radiological parameters between SIJP group and non-SIJP group. Postoperatively, SIJP group presented smaller LL (38.66 vs46.37, p=0.02), larger PT (19.93 vs14.14, p = 0.04), smaller SS (35.48 vs41.46, p = 0.04) and lower achieved rate of LL (%) (60.83 vs 71.54, p = 0.01) than non-SIJP group. Postoperative PT/PI and SS/PI showed significant difference (0.25 vs 0.34, p = 0.04; 0.74 vs 0.65, p = 0.04 respectively) between non-SIJP and SIJP group, and the post-operative ratios of non-SIJP group were similar with those of asymptomatic population (adopted from Mac-Thiong et al's data[1])) in contrast to SIJP group. Postoperatively, patients in SIJP group presented a significantly higher value of LL-PI mismatch than non-SIJP group (-16.76 vs -9.23; p = 0.01). Although correlation coefficients analysis revealed that the higher PI patients had, the more postoperative LL was restored in both groups, coefficient of correlation in SIJP group was lower (R = 0.559 vs 0.798) and statistically less powerful than that in non-SIJP group.(p< 0.05 vsp < 0.001).

Conclusion: The current study presents postoperative differences in the lumbopelvic sagittal alignment between patients with SIJP and patients without SIJP following PLIF. These differences herald that postoperatively insufficient restoration of LL and lumbo-pelvic sagittal imbalance may play a key role in the development of SIJP following PLIF. Consequently, postoperative SIJP might be avoidable as long as sufficient restoration of LL in accordance with PI and balanced lumbopelvic parameters is achieved in PLIF.

Reference: 1) Mac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P: Age- and sex-related variations in sagittal sacropelvic morphology and balance in asymptomatic adults.
Eur Spine J 20 Suppl 5: 572-577, 2011.