OBJECTIVETo discuss the advantages and disadvantages of two different surgical approaches combined fixation with lumbar interbody fusion in treating single segmental lumbar vertebra diseases.

METHODSThe clinical data of 86 patients with single segmental lumbar vertebra diseases treated from June 2011 to June 2013 was retrospectively analyzed. There were 33 males and 53 females, aged from 28 to 76 years old with an average of 53.0 years. Among them, there were 39 cases of lumbar disc degeneration, 22 cases of lumbar disc herniation complicated with spinal canal stenosis, 9 cases of huge lumbar disc herniation and 16 cases of lumbar degenerative spondylolisthesis (Meyerding degree I ). Lesion sites contained L3, 4 in 5 cases, L4, 5 in 70 cases and L5S1 in 11 cases. All the patients were treated with internal fixation and lumbar interbody fusion with 45 cases by midline incision approach (median incision group) and the other 41 cases by channel-assisted by muscle-splitting approach(channel group). Incision length, operation time, intraoperative bleeding and postoperative drainage were recorded in two groups. Visual analogue scale(VAS) was used to assess lumbar incision pain 72 h after operation. Depended on imaging results to compare the changes of the disc space height in lesion in preoperative, postoperative and final follow-up, the coronal and sagittal Cobb angle in preoperative and final follow-up, the area of multifidus and the degree of multifidus fat deposition before and after operation between two groups. Loosening or fragmentation of internal fixation, displacement of intervertebral cage and interbody fusion were observed in each group. Japanese Orthopedic Association (JOA) scoring system was used to evaluate the function before operation and at the final follow-up.

RESULTSThe channel group was superior to the median incision group in incision length and postoperative drainage while the median incision group was less than the channel group in the operation time and intraoperative bleeding. The average VAS score of lumbar incision 72 h after operation was 1.50 points in median incision group and 0.97 points in channel group, and there was significant difference between two groups(<0.05). No incision infection was found, but there were 4 cases of incisional epidermal necrosis, 1 case of incision healed badness, and 3 cases of nerve injury in channel group. The incidence of cacothesis of pedicle screw were 5.0% and 3.6% in median incision group and channel group respectively, and there was no significant difference between two groups(>0.05). The incidence of cacothesis of translaminar facet screw were 6.6% and 12.2% in median incision group and channel group respectively, and there was significant difference between two groups(<0.05). All the patients were followed up for 12 to 36 months with a mean of 22.8 months. The changes of disc space height had statistical difference between preoperative and postoperative(<0.05) in all patients, but there was no significant difference between postoperative and final follow-up(>0.05), however, there was no significant difference 3 days after operation and final follow-up between two groups(>0.05). At final follow-up, coronal and sagittal Cobb angle were obviously improved in all patients(<0.05), but there was no significant difference between two groups(>0.05). One year after operation, the area of multifidus in median incision group was (789.00±143.15) mm² less than preoperative(1 066.00±173.55) mm² (<0.05), and in channel group, was(992.00±156.75) mm² at 1 year after operation and(1 063.00±172.13) mm² preoperatively, there was no significant difference between them(>0.05), however, there was significant difference one year after operation between two groups (<0.05) . About the degree of multifidus fat deposition, there was significant difference between one year after operation and preoperation in median incision group (<0.05), but there was no significant difference between one year after operation and preoperation in channel group (>0.05), and there was significant difference at one year after operation between two groups(<0.05). During the follow-up period, neither pedicle screw and/or translaminar facet screw loosening, displacement or fragmentation nor displacement of intervertebral cage were found. The lumbar interbody fusion rate was 95.6% in median incision group and was 95.1% in channel group, and there was no significant difference between two groups(>0.05). No obvious adjacent segmental degeneration was observed in fixed position. JOA score in median incision group was significantly increased from 8-16 points (average: 12.77±2.56) preoperative to 21-29 points (average: 25.20±2.43) at final follow-up(<0.05); and in channel group was significantly increased from 8-16 points (average: 12.64±2.37) preoperative to 23-29 points(average: 26.7±1.82) at final follow-up(<0.05); there was also significant difference between two groups at final follow-up.

CONCLUSIONSCompared to the median incision approach, unilateral pedicle screw combined with contralateral translaminar facet screw fixation using channel-assisted by muscle-splitting approach has advantages of small incision, less trauma, fast recovery and so on. However, it also has shortages such as high surgical complications incidence, especially in cases that.