Correlation between correction of pelvic balance and clinical outcomes in mid- and low-grade adult isthmic spondylolisthesis.

BACKGROUND: Pelvic balance is a version of the pelvis defined by pelvic orientation parameters of PT and SS. Two distinct versions of pelvis are defined: (1) balanced characterized by a relatively low PT and high SS, and (2) unbalanced with relatively high PT and low SS meaning excessive retroversion of the pelvis. It was proved for patients with a high-grade spondylolisthesis that rebalancing of the pelvis can positively affect clinical outcomes. Little is known about the impact of such rebalancing in low-grade isthmic spondylolisthesis. PURPOSE: To determine whether clinical outcomes correlated with rebalancing of the pelvis after surgical correction of mid- and low-grade adult isthmic spondylolisthesis. METHODS: One hundred and three adult patients with a mid- and low-grade isthmic slip were the participants. Clinical outcomes were assessed at least 2 years after the surgery with the use of the Oswestry Disability Index (ODI) and a back pain visual analogue scale. Statistical analysis was used to identify differences in clinical outcomes between patients (1) with a balanced and unbalanced pelvis postoperatively, (2) who regained and did not regain pelvic balance postoperatively, (3) who maintained and lost pelvic balance postoperatively, and (4) with reduced and increased postoperative PT. RESULTS: There were no significant differences in clinical outcomes between patients with a balanced and unbalanced pelvis postoperatively regardless of whether they lost, maintained, or regained pelvic balance after the surgery (Student's t test for independent variables or the non-parametric Mann-Whitney U, p value = 0.05). No correlation (Spearman's rank correlation) was found between postoperative reduction of PT and postoperative: (1) level of back pain (r = -0.10, p = 0.3063), (2) degree of reduction in back pain (r = 0.03, p = 0.7927), (3) ODI scores (r = -0.18, p = 0.0696), and (4) degree of reduction in ODI scores (r = 0.13, p = 0.1893). CONCLUSIONS: Radiological improvement of pelvic balance after surgical correction of mid- and low-grade isthmic spondylolisthesis did not correlate with clinical outcomes.

Comparison of fusion rates between rod-based laminar claw hook and posterior cervical screw constructs in Type II odontoid fractures.

BACKGROUND: This study was aimed (i) to compare the fusion rates of rod-based laminar claw hook constructs to that of posterior C1/C2 screw constructs in odontoid fractures, and (ii) to evaluate any complications associated with claw hook/rod constructs. To our knowledge, no study in contemporary literature has presented the effects of using modern rod-based laminar claw hooks for treating odontoid fractures. Unlike laminar clamps from the 1980s, contemporary laminar hook-rod instrumentation systems provide better immobilisation of the cervical spine and allows for building reliable frame-like constructs similar to cervical screw-rod systems. METHODS: A retrospective review of a series of 167 consecutive odontoid fractures from a single-institution was conducted. 30 cases from the series were treated using posterior atlantoaxial fusion, 12 using C1/C2 posterior screws (control group), and 18 with rod-based laminar claw hooks (study group). Hooks were mounted bilaterally in a claw manner on each individual lamina and were rigidly fixed to perpendicular rods with a transverse connector whenever feasible. The minimum follow-up period was one year. Bony union was determined using computed tomography (CT) scan, while stability at the fusion site was assessed using dynamic radiograms. RESULTS: The study group had an overall fusion rate of 89% (non-geriatric 93% while geriatric subgroup 75%) with a 100% stability rate at the fusion site in all cases. In the control group fusion rate was 100%. There were no major complications in both control and study groups. Four minor complications, three in the control and one in the study group, were noted in 3 patients. CONCLUSION: Preliminary results of this study suggest that laminar claw hook-rod systems are useful alternatives to posterior screw techniques. Moreover, the fusion rate in non-geriatric patients is comparable to that of posterior screws. Importantly, they are devoid of the disadvantages and complications posed by screw constructs. Further studies are necessary to confirm these promising results.