Recent reports have demonstrated that intermittent treatment with parathyroid hormone (1-34) [PTH(1-34)]increases callus formation and mechanical strength in experimental fracture healing. However, little is known about the optimal dose required for enhancement of fracture repair or the molecular mechanisms by which PTH regulates the healing process. In this study, we analyzed the underlying molecular mechanisms by which PTH affects fracture healing and tested the hypothesis that intermittent low-dose treatment with human PTH(1-34) can increase callus formation and mechanical strength. Unilateral femoral fractures were produced and a daily subcutaneous injection of 10 g/kg of PTH (1-

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BackgroundThe importance of pelvic incidence-lumbar lordosis (PI-LL: PI minus LL) mismatch is emphasized in long-segment fusion for adult spinal deformity; however, there are few studies evaluating the influence of PI-LL on surgical outcomes after short-segment fusion. In this study, we have examined the effects of PI-LL mismatch on surgical outcomes of short-segment lumbar intervertebral fusion for lumbar degenerative diseases.MethodsPatients with lumbar degenerative disease treated by short-segment (1 or 2 levels) transforaminal lumbar interbody fusion were divided into Group A (PI-LL ≤ 10°: n = 22) and Group B (PI-LL ≥ 11°: n = 30). Pre-and post-operative patient symptoms were assessed by the visual analogue scale (VAS: scores 0-100 mm; for LBP, lower-extremity pain, and lower-extremity numbness), a detailed VAS for LBP while in motion, standing, and sitting, and the Oswestry disability index (ODI). Surgical outcomes were evaluated by the Nakai score (3 = excellent to 0 = poor. Post-operative data were acquired for at least one year following surgery and were compared between the two groups. Multiple regression analyses were used to evaluate the relative influence of PI-LL on each pre-and post-operative parameter (VAS, detailed VAS and ODI) adjusted for age, sex, fusion levels, body mass index, presence of scoliosis, diabetes mellitus and depression.ResultsThe surgical outcomes in Group A were significantly better than those of Group B. Group A showed better post-operative VAS scores for LBP, particularly LBP while standing (11.9 vs. 25.8). The results of the multivariate analyses showed no significant correlation between PI-LL and pre-operative symptoms, but did show a significant correlation between PI-LL and the post-operative VAS score for LBP, lower extremity pain, and numbness.ConclusionsThis study is the first to find that PI-LL mismatch influences post-operative residual symptoms, such as LBP, lower extremity pain and numbness. Among the three types of LBP examined in the detailed VAS, LBP while standing was most strongly related to PI-LL mismatch. The importance of maintaining spinopelvic alignment is emphasized, particularly when treating patients with adult spinal deformity using long-segment fusion surgery. However, our results indicate that surgeons should pay attention to sagittal spinopelvic alignment and avoid post-operative PI-LL mismatch even when treating patients with short-segment lumbar interbody fusion.

The results suggest that the use of a bullet-shaped cage, higher PDH, the presence of scoliotic curvature, and undersized fusion cages are possible risk factors for cage migration. One patient with postoperative cage migration following bilateral screw fixation underwent revision surgery, and the pedicle screw fixation was found to be disrupted. Other than in this patient, cage migration occurred only in those treated by unilateral fixation. The potential for postoperative cage migration and limitations of unilateral fixation should be considered by spine surgeons.

Object Many surgeons currently prefer to use transforaminal lumbar interbody fusion (TLIF), placing 1 unilateral pedicle screw (PS) and 1 cage. However, no study has examined whether unilateral fixation improves surgical outcome. The authors conducted a prospective randomized controlled trial with a minimum 2-year follow-up to analyze TLIF outcomes for 2 techniques: placement of a unilateral PS and a cage compared with placement of bilateral PSs and 2 cages. Methods Fifty patients with degenerative spondylolisthesis undergoing single-level TLIF were randomly assigned to receive either unilateral or bilateral fixation. Parameters compared between the groups were surgical invasiveness, severity of intermittent claudication, pre- and postoperative visual analog scale (VAS) scores (from 0 to 10 for back pain, lower-extremity pain, and lower-extremity numbness), postoperative disability scores for lumbar spinal disorders (Japanese Orthopaedic Association Back Pain Evaluation Questionnaire [JOABPEQ]), and fusion rates. Results The mean operative time for TLIF was significantly (p = 0.05) shorter and mean estimated blood loss was significantly lower in the unilateral than in the bilateral group. Intermittent claudication improved in response to each technique, but there was no significant intergroup difference. The unilateral group had a nonsignificant tendency toward less improvement in VAS score for back pain (1.5 vs 3.7 for the bilateral group) and exhibited significantly less improvement in VAS score for lower-extremity pain (2.1 vs 5.1, respectively) and numbness (1.7 vs 4.4). There were no significant differences between the groups in postsurgical scores for all 5 items of the JOABPEQ. The fusion rates were 87.5% (21 of 24 patients) in the unilateral group and 95.7% (22 of 23) in the bilateral group. Conclusions Transforaminal lumbar interbody fusion involving unilateral PS fixation and a single-cage technique is less invasive than a 2-cage technique and bilateral fixation, and it improved patients' symptoms. However, it resulted in less improvement in back pain, lower-extremity pain, and lower-extremity numbness. When considering unilateral PS fixation and a single cage, the surgeon should be aware of the potential limitations of this technique. Clinical trial registration no.: UMIN000007833 (UMIN).