[An anatomic study of glenoid regarding anchor insertion posion and direction].

OBJECTIVE: To investigate normal bony anatomy of the glenoid rim, to measure inner glenoid rim angle and outer glenoid rim angle, and the angles for successful anchor insertion for arthroscopic labral repairs. METHODS: Twelve unpaired isolated human glenoids (6 right, 6 left) without any evidence of trauma were for studying. The glenoid specimens were scanned using 320-slice CT (Aquilion ONE), then reconstruction glenoid to a three dimensional model using materialise's interactive medical image control system (Mimics) and to obtain cross-sectional images in 6 different planes, mark the right glenoid rim with clockwise tag, the left with counterclockwise tag. Inner glenoid rim angle marked as angle α and outer glenoid rim angle marked as angle ß were measured from the cross-sectional images of the glenoids at 8 positions: 2-, 3-, 4-, 5-, 6-, 7-, 8- and 9-o'clock positions. Glenoid morphology was noted for each position. Using 12 mm as radius, measured the minimum insertion angle of anchor, marked as angle γ. Normal distribution of the data was confirmed with Kolmogorov-Smirnov test. Paired t-test was performed to detect differences in the angles between two locations. Two independent samples t-test was performed to detect differences in the angles between same location of left and right. Analysis of variance (ANOVA) was performed to detect differences in the angles between right and left, and different locations of the glenoid rim. RESULTS: The smallest α was at the 4-o'clock position (right 50° ± 6°, left 52° ± 9°), significant difference were seen when compared with the 6-o'clock position (t = 10.466, P = 0.000) or the 5-o'clock position (t = 3.754, P = 0.003), no significant difference exist between 4-o'clock position and 3-o'clock posion (t = 0.926, P = 0.374). The smallest ß was at the 3-o'clock position (right 50° ± 6°, left 53° ± 10°), significant difference were seen when compared with the 6-o'clock position (t = 9.862, P = 0.000) or the 5-o'clock position (t = 3.634, P = 0.003), no significant difference exist between 4-o'clock position and 3-o'clock posion (t = 0.697, P = 0.501). Asymmetric morphology of the glenoid was noted with an almost straight line extending medially from the rim at the 3-o'clock position, whereas a concave morthology was noted at the 9-o'clock position. Similary at the 4- and 5-o'clock position, the scapular bony surface did not curve toward the base as markedly as it did at the corresponding posterior 8- and 7-o'clock position. Angle γ from the 3-o'clock to the 9-o'clock were 25° ± 4°, 54° ± 6°, 83° ± 4°, 119° ± 2° at right side, 23° ± 4°, 57° ± 4°, 89° ± 7°, 119° ± 4° at left side. No significant difference of any angle at the same position was noted between left and right (α:t = 0.283-1.785, P > 0.05;ß:t = 0.369-2.067, P > 0.05;γ:t = 0.145-0.492, P > 0.05). CONCLUSIONS: The available bone mass for the anchor insertion is found to vary depending on the position of the glenoid rim. The smallest inner and outer glenoid rim angle are at the 4- and 3-o'clock position. The minimum insertion angles of anchor differ at different position. Both rim angle and glenoid morthology for each position must be considered when selecting the ideal anchor insertion angle for Bankart repair. Meanwhile, minimum insertion angle of anchor should also be considered before anchor insertion.

Comparison of three different surgical approaches for treatment of thoracolumbar burst fracture.

OBJECTIVE: The main treatment method used for thoracolumbar fractures is open reduction and internal fixation. Commonly there are three surgical approaches: anterior, posterior and paraspinal. We attempt to compare the three approaches based on our clinical data analysis. METHODS: A group of 94 patients with Denis type A or B thoracolumbar burst fracture between March 2008 and September 2010 were recruited in this study. These patients were treated by anterior-, posterior- or paraspinal-approach reduction with or without decompression. The fracture was fixed with titanium mesh and Z-plate via anterior approach (24 patients), screw and rod system via posterior approach (38 patients) or paraspinal approach (32 patients). Clinical evaluations included operation duration, blood loss, incision length, preoperative and postoperative Oswestry disability index (ODI). RESULTS: The average operation duration (94.1 min +/- 13.7 min), blood loss (86.7 ml +/-0.0 ml), length of incision (9.3 mm +/- 0.7 mm) and postoperative ODI (6 +/- 0.5) were significantly lower (P less than 0.05) in paraspinal approach group than in traditional posterior approach group (operation duration 94.1 min +/- 13.7 min, blood loss 143.3 ml +/-28.3 ml, length of incision 15.4 cm +/- 2.1 cm and ODI 12 +/- 0.7) and anterior approach group (operation duration 176.3 min +/- 20.7 min, blood loss 255.1 ml +/- 38.4 ml, length of incision 18.6 cm +/- 2.4 cm and ODI 13 +/- 2.4). There was not statistical difference in terms of Cobb angle on radiographs among the three approaches. CONCLUSION: The anterior approach surgery is convenient for resection of the vertebrae and reconstruction of vertebral height, but it is more complicated and traumatic. Hence it is mostly used for severe Denis type B fracture. The posterior approach is commonly applied to most thoracolumbar fractures and has fewer complications compared with the anterior approach, but it has some shortcomings as well. The paraspinal approach has great advantages compared with the other two approaches. It is in accordance with the concept of minimally invasive surgery and can replace most posterior approach operations.

[Experiment of rhBMP-2 in posterolateral spinal fusion in aged rabbits].

OBJECTIVE: Posterolateral intertransverse process fusion was performed in aged and young adult female rabbits lumbar spine using recombinant human bone morphogenetic protein-2 (rhBMP-2) and autograft to reveal the function of rhBMP-2 on spinal fusion on aged animals. METHODS: A total of 24 female New Zealand white rabbits included 12 young adult of 6 months and 12 aged of 2-year-old, was divided into 4 groups: (1) young adult autologous iliac crest bone group [ICBG(Y), n=6); (2) young adult rhBMP-2/absorbable collagen sponge (ACS) group [BMP-2(Y), n=6]; (3) aged autologous iliac crest bone group [ICBG(O), n=6]; aged rhBMP-2/ACS group [BMP-2(O), n=6]. All were underwent posterolateral fusion in same day. rhBMP-2 and autologous iliac crest bone was implant bilateral LS-L6 intertransverse processes, respectively. Half of the rabbits were sacrificed at 3.6 weeks following surgery, respectively. The results were assessed by manual palpation, radiographs, computed tomographic scans (3D) and histology. RESULTS: Six weeks after surgery, radiography, computed tomography and histology indicated the different result in healing in the posterolateral fusion using rhBMP-2 compared to ICBG (P < 0.05). Aged BMP-2 group showed significantly higher fusion rates than Aged ICBG group. CONCLUSION: This study demonstrated rhBMP-2 can increase the posterolateral fusion rate and new bone quality in aged rabbitss than autograft, it may take the place of ICBG. But its role is effected by age.