Setting property and compressive strength of nHA/α-CSH combined bone grafts / 医用生物力学

Objective To develop a new type of combined bone grafts mainly including nanometer hydroxyapatite (n-HA) and α-calcium sulphate hemihydrate (α-CSH), and investigate its setting property and compressive strength. Methods The setting time and compressive strength of nHA/α-CSH combined bone grafts with different liquid-to-solid (L/S) ratio or calcium sulphate dehydrate (CSD) amount were measured and observed by the X-ray diffraction (XRD) and the scanning electron microscope (SEM). Results The setting time of combined bone grafts was increased along with the increase of L/S ratio or nHA amount, and reduced with the increase of CSD amount. The setting time of the compound with 20% of nHA, 80% of α-CSH was (169±36) min, while that of the compound with 5% of nHA, 20% of CSD, 75% of α-CSH was (6±1.1) min. The compressive strength of combined bone grafts reduced along with the increase of nHA amount. The average compressive strength of pure α-CSH was (12.3±2.4) MPa, while that of the compound with 20% of nHA, 80% of CSH was (4.8±0.6) MPa. The XRD results showed that no other materials were produced except that α-CSH was transformed to CSD during the setting process. The SEM results indicated that nHA was filled in the crystal structure of the CSD, presenting two-phase structure. Conclusions The setting time and compressive strength of nHA/α-CSH combined bone grafts can be adjusted by the different proportion of nHA, CSD amount and L/S ratio, which provides an appropriate condition for clinical application.

A feasibility research of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) using hybrid internal fixation for recurrent lumbar disc herniation / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the feasibility of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) using hybrid internal fixation of pedicle screws and a translaminar facet screw for recurrent lumbar disc herniation.</p><p><b>METHODS</b>From January 2010 to December 2011, 16 recurrent lumbar disc herniation patients, 10 male and 6 female patients with an average age of 45 years (35-68 years) were treated with unilateral incision MIS-TLIF through working channel. After decompression, interbody fusion and fixation using unilateral pedicle screws, a translaminar facet screw was inserted from the same incision through spinous process and laminar to the other side facet joint. The results of perioperative parameters, radiographic images and clinical outcomes were assessed. The repeated measure analysis of variance was applied in the scores of visual analogue scale (VAS) and Oswestry disablity index (ODI).</p><p><b>RESULTS</b>All patients MIS-TLIF were accomplished under working channel including decompression, interbody fusion and hybrid fixation without any neural complication. The average operative time was (148 ± 75) minutes, the average operative blood loss was (186 ± 226) ml, the average postoperative ambulation time was (32 ± 15) hours, and the average hospitalization time was (6 ± 4) days. The average length of incision was (29 ± 4) mm, and the average length of translaminar facets screw was (52 ± 6) mm. The mean follow-up was 16.5 months with a range of 12-24 months. The postoperative X-ray and CT images showed good position of the hybrid internal fixation, and all facets screws penetrate through facets joint. The significant improvement could be found in back pain VAS, leg pain VAS and ODI scores between preoperative 1 day and postoperative follow-up at all time-points (back pain VAS:F = 52.845, P = 0.000;leg pain VAS:F = 113.480, P = 0.000;ODI:F = 36.665, P = 0.000).</p><p><b>CONCLUSION</b>Recurrent lumbar disc herniation could be treated with MIS-TLIF using hybrid fixation through unilateral incision, and the advantage including less invasion and quickly recovery.</p>

A feasibility research of unilateral incision minimally invasive transforaminal lumbar interbody fusion using pedicle screws and a translaminar screw hybrid fixation / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the feasibility and safety of unilateral incision hybrid fixation using pedicle screws and a translaminar screw in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).</p><p><b>METHODS</b>From January to June 2010, 18 patients with single-level lumbar disc disease were treated with MIS-TLIF under METRx(TM) X-tube. After decompression and fixation using unilateral pedicle screws, a translaminar screw was inserted from the same incision to the other side. The results of perioperative parameters, radiographic images and clinical outcomes were assessed.</p><p><b>RESULTS</b>All patients underwent MIS-TLIF were accomplished unilateral hybrid fixation without any neural complication. The average operative time was (107 ± 19) min, the average operative blood loss was (62 ± 21) ml, and the average postoperative ambulation time was (21 ± 5) h. The average length of translaminar facets screw was (52 ± 2) mm, and the postoperative images showed all screws penetrate through facets joint. During the follow-up the visual analogue scale and Oswestry disability index scores were significant improved compared with preoperative (F = 42.221 - 259.833, P < 0.01).</p><p><b>CONCLUSIONS</b>Bilateral hybrid fixation could be completed through unilateral incision by pedicle screws and a translaminar screw in MIS-TLIF, and the advantage including less invasion, quickly recovery, short operative time, and saving fixation cost.</p>