Clinical features and surgical outcomes of lumbar spinal stenosis in patients aged 80 years or older: a multi-center retrospective study.

INTRODUCTION: With increased aging of the population, spine surgeons have more opportunity to treat elderly patients for lumbar spinal stenosis (LSS). The purpose of this study was to clarify the clinical features and surgical outcomes for LSS in the elderly aged 80 years or older. MATERIALS AND METHODS: We retrospectively reviewed 702 consecutive patients with LSS who underwent decompression surgery without fusion between 2006 and 2010. Patients with other conditions that could affect functional status were excluded from this study. Of the remaining 304 patients, 241 with LSS whose condition could be evaluated 6 months at least after surgery were analyzed. The mean follow-up period was 14.4 months (range 6-60 months). There were 144 males and 97 females aged 45-93 years old (average: 72.2 years old). Patients were divided into two age groups: 80 years or older (Group A, 46 patients) and under 80 years of age (Group B, 195 patients). We evaluated differences in the clinical features and surgical outcomes between the two groups. RESULTS: There were no significant differences in surgical levels, the number of operation levels, operation times, or the amount of intraoperative bleeding between Groups A and B. The percentages of patients with comorbidities were 73.9 % in Group A and 60.0 % in Group B, which were not significantly different. There were no significant differences in Japanese Orthopaedic Association scores preoperatively, 6 months postoperatively, and at the final follow-up between the two groups. Furthermore, recovery ratios 6 months postoperatively and at final follow-up were similar between the two groups. The percentages of patients with postoperative complications were 19.6 % in Group A and 13.3 % in Group B, which were not significantly different. CONCLUSIONS: This multi-center retrospective study demonstrated that the benefits and risks of decompression surgery for LSS were similar between patients aged over 80 years and those under 80 years. Therefore, decompression surgery is a reasonable treatment even for elderly patients aged over 80 years.

Effects of minodronate on cortical bone response to mechanical loading in rats.

The effects of BPs on bone formation during mechanical loading are still unknown. In this study, we evaluated the effect of minodronate on the cortical bone response to mechanical loading applied using a 4-point bending device. We used six-month old female Wistar rats and randomized into five groups (N=10/group): Vehicle administration (VEH), low dose minodronate administration (MIN-L, 0.01 mg/kg BW), middle dose minodronate administration (MIN-M, 0.1mg/kg BW), high-dose minodronate administration (MIN-H 1mg/kg BW), and very high-dose minodronate administration (MIN-VH, 10mg/kg BW). Minodronate or vehicle was administered orally using the feeding needle at a dosage 3 times/week for 3 weeks. Loads on the right tibia at 38 N for 36 cycles at 2 Hz were applied in vivo by 4-point bending on the same day for 3 weeks. After calcein double labeling the rats were sacrificed and tibial cross sections were prepared from the region with maximal bending at the central diaphysis. Histomorphometry was performed at the entire periosteal and endocortical surface of the tibiae, dividing the periosteum into lateral and medial surfaces. The formation surface was reduced significantly in MIN-H and MIN-VH groups at the medial surface, and in MIN-VH group at the endocortical surface of the loaded tibia (p<0.01 vs. VEH). The mineral appositional rate was reduced significantly in MIN-H and MIN-VH groups at the endocortical surface of the loaded tibia (p<0.01 vs. VEH). The bone formation rate was significantly reduced in MIN-H group at the medial surface, and in MIN-H and MIN-VH groups at the endocortical surface of the loaded tibia (p<0.01 vs. VEH). However, no significant differences were observed in any parameters between the VEH group and either the MIN-L or MIN-M groups for both the loaded and non-loaded tibiae. Based on previous preventive studies in OVX rats, the optimal dose of minodronate for the treatment of osteoporosis would be 0.03 mg/kg (0.21 mg/kg/week). Therefore, we used 0.1mg/kg of minodronate 3 times/week (0.30 mg/kg/week) that was close to 0.21 mg/kg/week. In conclusion, minodronate does not reduce the cortical bone response to mechanical loading at the optimal dose for the treatment of osteoporosis in rat model.

Clinical features and surgical outcomes of cervical spondylotic myelopathy in patients aged 80 years or older: a multi-center retrospective study.

With the aging of the population in developed countries, spine surgeons have recently been more likely to encounter elderly patients in need of treatment. This study investigated whether decompression surgery for cervical spondylotic myelopathy (CSM) in elderly patients aged 80 years or older would likely be a reasonable treatment. We retrospectively reviewed 605 consecutive patients with cervical myelopathy who underwent decompression surgery between 2004 and 2008. Patients with other conditions that could affect functional status or compression factors other than spondylosis were excluded from this study. Of the remaining 189 patients, 161 with CSM whose condition could be evaluated 6 months after surgery were analyzed. The patients were divided into two age groups: 80 years or older (Group A, 37 patients) and younger than 80 years of age (Group B, 124 patients). We evaluated the differences in symptom duration, clinical data, involved levels, surgical outcome, comorbidities, and postoperative complications between the two groups. The symptom duration was significantly shorter in Group A. The average JOA scores preoperatively and 6 months postoperatively were significantly lower in Group A; however, there was no significant difference in the recovery ratio. There were no significant differences in the percentages of patients with comorbidities or those with postoperative complications. Elderly patients aged 80 years or older regained approximately 40% of their function postoperatively, and the incidence of postoperative complication was similar to that in younger patients. Since this age group shows a rapid deterioration after onset, prompt decompression surgery is required.

Effect of intermittent administration of human parathyroid hormone on bone mineral density and arthritis in rats with collagen-induced arthritis.

OBJECTIVE: To investigate the effect of intermittent administration of human parathyroid hormone (PTH) on bone mineral density (BMD) and arthritis in rats with collagen-induced arthritis (CIA). METHODS: Seven-month-old female Sprague-Dawley rats were divided into 4 groups: rats without CIA (control), rats with CIA treated with vehicle, rats with CIA treated with PTH for 4 weeks, and rats with CIA treated with PTH for 6 weeks. PTH (20 mug/kg) was injected subcutaneously 3 times per week. BMD in the proximal metaphysis and the diaphysis of the tibia was measured by peripheral quantitative computed tomography every 2 weeks until week 8. Eight weeks after initial sensitization, the animals were killed, and the BMD and mechanical properties of excised limbs were evaluated. Histomorphometric analysis of tibiae and histologic evaluation of arthritis were also performed. RESULTS: In the PTH-treated rats with CIA, the incidence and severity of arthritis were macroscopically and histologically similar to the findings in the vehicle-treated rats with CIA. The decrease of BMD caused by CIA was suppressed by treatment with human PTH, in a manner that was dependent on the duration of administration. In the histomorphometric analysis, bone formation parameters were higher and bone resorption parameters were lower in the PTH-treated arthritic rats compared with vehicle-treated arthritic rats. Mechanical properties were also maintained in the PTH-treated rats. CONCLUSION: Our findings indicate that, in an animal model of arthritis, intermittent PTH administration activates bone formation, resulting in increased BMD and preventing deterioration of mechanical properties. However, PTH has no effect on the arthritis itself.

Bone response to mechanical loading in adult rats with collagen-induced arthritis.

To elucidate the effects of inflammation on the response of bone to mechanical stress, we performed experiments using a rat with collagen-induced arthritis (CIA) model. Six-month-old female Wistar rats were used in the experiment. Bovine type II collagen sensitization and additional sensitization after 1 week were preformed in all CIA groups. Loads were applied using a four-point bending device. The right tibia was loaded in both CIA and control (CONT) groups at 35 N (low groups), 40 N (medium groups), or 47 N (high groups) for 36 cycles at 2 Hz three times per week for 3 weeks. Histomorphometrical data were collected from the periosteal and endosteal surfaces of the tibia in all rats. The tibia periosteal surface was subdivided into lateral and medial surfaces. Formation surface (FS), mineral apposition rate (MAR) and bone formation rate (BFR) were calculated. At lateral surface of periosteal surface, all three parameters showed significant differences between the loaded and nonloaded tibiae. All these parameters were significantly lower in CIA groups than in CONT groups, and interaction was seen between applied loading and CIA. There was a significant correlation between peak strain and the right-left difference of FS in the CONT groups. At medial surface of periosteal surface, there were force-related increase in FS, MAR, and BFR on the loaded side in both CIA and CONT groups, except MAR in the CONT group. All three parameters showed significant differences between the loaded and nonloaded tibiae. At endocortical surface, force-related increase was observed only in FS on the loaded side in CONT groups, and FS was significantly higher on the loaded side than the nonloaded side. CIA lowered all three parameters significantly. We examined the response to mechanical loading on the tibia in untreated CONT rats and rats with CIA by bone histomorphometry, and found that arthritis suppressed bone formation induced by mechanical loading.