The major advantage of minimally invasive procedures in spinal surgery lies in their reduction of unnecessary exposure and tissue trauma. Minimally invasive procedures have become increasingly popular for the treatment of a wide range of pathologic conditions of the spine, including infections, tumors, deformities and frac- tures. Minimally invasive procedures used in the decompression of lumbar spinal stenosis caused by spondylosis include, unilateral procedure-characterized by unilateral multifidus retraction, ipsi- lateral decompression, and also contralateral microscopic decom- pression-performed under the midline bony and ligamentous structures1,5,8,11). For spinal arthrodesis, mini-anterior lumbar inter- body fusion (ALIF) or laparoscopy-assisted ALIF have been used in minimally invasive techniques3,6). However, posterior decom- pression, posterior lumbar interbody fusion (PLIF) and percuta- neous pedicle screw fixation for lumbar spinal stenosis using a minimally invasive procedures has not been reported.
The present study was performed to evaluate the technical fea-
sibility and efficacy of mini-open posterior decompression and PLIF.
MATERIALS AND METHODS 1. Materials
Eight patients with single level spinal canal stenosis at L4-5 underwent posterior decompression and PLIF with the mini-open technique. The patients consisted of two men and six women.
Mean age at the time of operation was 64.9 years (Table 1). Five patients had spinal canal stenosis with degenerative spondylolis- thesis, and four of the eight patients had preoperative neurologic deficits secondary to root compression. All patients had neurogenic intermittent claudication and low back pain (Fig. 1).
2. Surgical technique
Under fluoroscopic guidance with general anesthesia in a prone position, anatomical landmarks, including the vertebral pedicles, bodies and both end plates, were drawn on the skin. The position of disc space was perpendicularly to the ground for the purpose of a good working trajectory.
The skin incision was made at the lateral margin of pedicle on the side of the approach, approximately 1 inch long. A small stab
492 492 492 492 Address reprint requests to
Ki-Tack Kim, M.D.
Department of Orthopaedic Surgery, School of Medicine, Kyung Hee University 1 Heogi-dong, Dongdaemun-gu, Seoul 130-702, Korea
Tel: +82.2-958-8371 , Fax: +82.2-964-3865 E-mail: [email protected]
Purpose:To introduce mini-open posterior decompression with posterior lumbar interbody fusion (PLIF) and to assess its clinical outcomes.
Materials and Methods:Eight patients who underwent L4-5 posterior decompression with PLIF using a mini-open technique were followed up for an average 8 months. Three patients had degenerative lumbar spinal stenosis and five patients had spinal stenosis with degenera- tive spondylolisthesis. We performed posterior decompression with PLIF through a mini-incision (2.5 cm paramedian incision at the both sides) including percutaneous pedicle screw fixation. The operative time, amount of blood loss and complications were analyzed. Clinical outcomes were assessed by using McNab criteria and VAS (visual analogue scale) for postoperative back pain.
Results:The mean operative time was 172.5 min (range, 130-235 min). The mean amount of intraoperative blood loss was 178.1 mL (range, 95-310 mL). All procedures were completed without transfusion. VAS for back pain rapidly reduced from 10 on the immediate postop- erative day to 3 on the third day and 2 on the seventh day. At the last follow up, five patients had no back pain and the three remaining patients had a VAS 0.75. The clinical outcomes were excellent in 5 patients and good in 3 patients.
Conclusion:Mini-open posterior decompression and the PLIF technique offer a useful minimally-invasive modality for the treatment of single level spinal stenosis.
Key Words:Minimally invasive, Mini-open, Posterior lumbar interbody fusion (PLIF)
The Posterior Decompression and Posterior Lumbar Interbody Fusion Using a Mini-open Technique
- New Suggestion of Minimally Invasive Technique - A Preliminary Report
Ki-Tack Kim, M.D., Kyung-Soo Suk, M.D., Young-Ho Lee, M.D., Young-Woo Kim, M.D.*, Sang-Hun Lee, M.D.*
Department of Orthopaedic Surgery, School of Medicine, Kyung-Hee University, Seoul;
Department of Orthopaedic Surgery, Hallym University*, Chuncheon, Korea
incision was then made at the lumbodorsal fascia. Serial dilators with an access port were then passed over the smallest dilator to gently dilate the lumbar musculature and to expand the lum- bodorsal fascia away. The 22-mm diameter final working chan- nel was then passed over the dilators and secured to a flexible-arm
retractor mounted to the side rail of the table. Final fluoroscopic confirmation of the working channel position was then obtained, and the serial dilators were removed. Pituitary rongeur and mo- nopolar cautery were used to remove any residual muscular tissue in the tubular retractor for a clear operation field (Fig. 2B).
After exposing the facet joint and lamina, facetectomy and cen- tral decompressive laminectomy were performed through the access port from the inferior articular process to the isthmus, ce- phalad and to the base of the spinous process medially, using a small osteotome and Kerrison’s rongeur. In this fashion, the lateral recess and foraminotomy over the nerve root were decompressed.
To begin the interbody fusion, a small endoscopic scalpel was used for discectomy after had been well visualized the annulus.
Curettes including ring shaped, toothed and rotating curettes (Fig. 3) were used for the complete removal of disc material and cartilaginous end pates, with attention for root and dura injury (Fig. 4). The same procedures were performed on the contralat-
*SS: Spinal stenosis; �SPLT: degenerative spondylolithesis.
Drainage (mL) Postop.
Intraop.
Op. time (min) Diagnosis
KSS F/76 SS*, SPLT� 235 210 194
OMW M/58 SS 200 300 317
HKO F/67 SS, SPLT 130 230 197
MSJ F/62 SS 165 150 266
SES M/78 SS, SPLT 160 95 285
YYS F/47 SS, SPLT 185 200 365
KWY F/67 SS 155 125 320
LYD F/64 SS, SPLT 150 115 295
Table 1.Patient demographics
A B
Fig. 1.(A) The radiographs of a 76-year-old woman who had a radicular pain at both lower extremities and neurogenic intermittent clau- dication. (B) The MR images of the patient, showing severe central canal stenosis.
A B
Fig. 2.(A) Photograph of the serial dilators with access ports. (B) Photograph of procedures via the dilation port using the paramedian approach.
eral side.
Intervertebral cages filled with morcellized chips of bone ob-
tained from lamina and an articular process was inserted for inter-
body fusion through the access port. The space between the two cages was filled with remaining bone chips before inserting the second cage.
After decompression and interbody fusion, the access port was removed and percutaneous posterior instrumentation was per- formed with cannulated screws and a percutaneous rod insertion system (Fig. 5, 6), through the previously made skin incisions on both sides.
The wound was closed over a suction drain with suturing of the lumbodorsal fascia, subcutaneous layer and skin using absorbable sutures.
Ambulation was encouraged from one day after surgery accord- ing to patient condition. The suction drain was removed when postoperative drainage was less then 50 mL over 24 hours. Post- operative TLSO bracing was used for 3 months.
Data regarding blood loss, operative time, postoperative dra-
A B
Fig. 4.(A) C-arm image was taken to demonstrate curettage of the intervertebral disc and insertion of the cages. (B) Endoscopic image was taken to demonstrate the status of decompression and the preparation of disc space. Arthroscopy and C-arm were used for demon- stration only in this paper.
L4 root
L4-5 dura disc space Fig. 3. Photographs showing the various curettes used for disc
space preparation.
Fig. 5. Photographs of the percutaneous instrumentation system.
Showing the cannulated screws and percutaneous rod insertion system for minimally invasive spinal instrumentation.
Fig. 6. Postoperative radiographs of a patient showing well posi- tioned of pedicle screws and interbody cages.
inage, time for ambulation and duration of hospital stay were collected for each procedure. We also assessed the size of the sur- gical scar and complications. Postoperative back pain was mea- sured using a 0 to 10 visual analog scale (VAS-with 10 being the worst possible pain) at the postoperative first, third and seventh days and at the last follow up day. Overall clinical outcomes were assessed according to McNab’s criteria.
RESULTS
The mean operative time was 172.5 minutes (range, 130-235 minutes). The mean estimated blood loss was 178.1 mL (range, 95-310 mL). None of the patients needed transfusion postoper- atively or intraoperatively. A postoperative closed suction drain was placed in all patients, and the average total drainage was 280 mL (range, 194-317 mL). The drain remained in place for 2.5 days (range, 2-3 days). Ambulation with bracing was permitted on the postoperative second day. The mean hospital stay was 7 days (range, 5-12 days).
Significant reductions in pain and significant improvements in function were observed in all patients. Overall, five patients rated their outcomes as excellent and three patients as good, using McNab’s criteria. The VAS of back pain decreased rapidly from a mean of 5.5 (4.5-6.5) on the first day after surgery to 3.0 (2.5- 4.0) on third day and to 2.0 (1.5-3.0) at 1 week. At the final fol- low-up, five patients had no back pain and the remaining three patients had VAS 0.75 (0.5-1.5). The patients’ satisfactions with the minimal skin incisions were good in all cases (Fig. 7).
Radiologic findings showed complete decompression of lamina and facet joints with preservation of spinous process, interspinous and supraspinous ligaments (Fig. 8). All radiographs at the final follow up showed solid union of the fused segments.
We performed surgical exploration in one case (Case 6) who showed no neurological deficit untill the postoperative third day when the patient developed weakness of the big toe and ankle extensor. We found no definite pathologic findings. The weakness resolved progressively over 4 weeks. One dural tear (Case 8) of 1-2 mm size occurred around the L4 root. For a narrow operative field, we used a gelfoam sponge packing with fibrin glue instead of repair. No other complication occurred postoperatively.
DISCUSSION
The traditional surgery for stenosis includes an extensive resec- tion of the posterior spinal structures such as, the interspinous ligaments, spinous processes, bilateral lamina, facet joints with capsule and the ligamentum flavum. These classic operations of wide decompressive laminectomy, medial facetectomy, and fora- minotomy have been used for decades with varying degrees of success.
However, such extensive injury to the paraspinal structures is associated with significant pain, a long hospitalization period, perioperative morbidities, a prolonged recovery period, and an increased incidence of medical complications such as, deep vein thrombosis, pulmonary and urinary tract problems. These com- plications occur as part of an exaggerated surgical stress response.
Extensive surgical tissue trauma can also result in delayed func- tional sequelae. Loss of the midline posterior ligament complex can lead to a loss of flexion stability, thereby, increasing the risk of adjacent segment instability. Extensive muscle retraction dur- ing open surgery results in reduced paraspinal muscle strength with chronic denervation, atrophy of muscles and the increased incidence and intensity of postoperative back pain7,12,13).
Minimally invasive techniques may effectively reduce unneces-
Fig. 7. The clinical photograph showing operation scar 3 months after operation. The size of scar was 2.5 cm on the paramedian side and 1cm at the midline, for rod insertion.
Fig. 8. 3-dimension- al CT reconstruction films showing com- plete decompression of spinal canal as well as preservation of the posterior portion of the spinous process (large arrow) and re- lated ligaments. Note the sufficiency of bo- ne inserted in and be- tween the two cages (small arrows).
sary tissue damage, and therefore, decrease the incidence of these complications.
Due to these considerations, the feasibility of decompressing the spinal canal by less invasive methods has been explored by numerous authors4,16). Under the operating microscope, unilat- eral microscopic hemilaminotomy was developed as a means of sparing the contralateral musculature characterized by ipsilateral decompression, and contralateral microscopic decompression, per- formed under the midline bony and ligamentous structures th- rough the posterior midline or paramedian approach9,10). A cadav- eric and limited clinical study of the bilateral approach using mi- croendoscopic discectomy system (MED), was reported recent- ly1,8). However, these techniques have the potential risk of incom- plete decompression or neural injury for a limited surgical field.
Significant strides in endoscopic surgical visualization have been made during the past decade, microendoscopic discectomies (MED) have been used for treating herniated discs successfully over the past several years in the lumbar spine14). This procedure is attractive because of a small skin incision (18 mm), less muscle dissection, excellent visualization around neural structures, and because it has the ability to achieve results equivalent to those of open techniques. But, the MED technique has a substantial learn- ing curve and the investment of time for training should be antic- ipated.
In this study, an Access Dilation Port, a type of tubular retractor (22 mm diameter) was used as the working channel for all proce- dures, repositioning the working channel enabled us to perform all procedures under clear vision and to achieve same goals as the classical open techniques. Although the tubular port has a small diameter (22 mm) and offers a narrow field, it permits clear surgi- cal vision and allows a more meticulous procedure than the open field. This may be explained by the ‘diffraction of light’ which increases the intensity of light waves through a small slit2).
For fusion methods in minimally invasive techniques, mini- anterior lumbar interbody fusion (ALIF)3)or endoscopy-assisted ALIF have been commonly used6,15). An attempt at posterior de- compression using the MED system and a non-instrumented fusion technique was made recently.
However, posterior decompression and posterior lumbar inter- body fusion (PLIF) for lumbar spinal stenosis with minimally invasive procedures has not been reported upon.
Even though, there is some controversy as to whether instru- mented fusion should be performed in conjunction with decom- pressive surgeries for spinal canal stenosis, this is the first report to find that the all procedures of PLIF can be accomplished using the minimally invasive, paramedian approach.
The advantages of the mini-open technique are obvious. First, the approach is minimally invasive with limited destruction of the posterior ligament complex. The spinous process, supraspinous ligament and interspinous ligament are not sectioned. In the authors’ opinion, the acceleration of adjacent segment degenera- tion may be markedly reduced for this reason.
The cosmetic aspects of the mini-open approach are favorable (two paramedian 1 inch incisions), when compared with the scar associated with a standard open procedure.
The avoidance of excessive retraction of the paraspianal muscles may contribute to postoperative back function. In the classical approach, subperiosteal dissections are performed between bone and muscle, which produced a fibrous scar tissue. Using the au- thors’ technique, healing is accomplished within muscles. The rapid amelioration of back pain observed in this study is sugges- tive of such an advantage. It may be also attributable to postoper- ative early ambulation and reduced surgical morbidity in the elderly.
Although a control group was not established, the estimated blood loss (av. 178.1 mL) and the postoperative drainage (av. 280 mL) in this series were considerably less than we normally expe- rience experience using the classical technique. No patient in this series needed transfusion. For the first 3 cases, the intraoperative blood loss was more than 200 mL, whereas in the next 5 cases the intraoperative blood loss was around 100 mL, and was less than 300 mL including postoperative drainage.
Potential disadvantages of the mini-open technique could be suggested. The mini-open technique may be technically demand- ing, and has a significant learning curve. Procedures under narrow surgical field have the potential risk of neural structure injury and present difficulties repairing a dural tear.
In term of operative time, it was similar to that of the open procedures (the average in this series was 165 minutes). Although, the time for decompression and interbody fusion was longer than of classical open procedures, the time for open dissection and clo- sure was shorter. During the course of this consecutive series, the total operative time continued to decrease.
CONCLUSION
This study suggests that posterior decompression and PLIF using a mini-open technique has a better chance of relieving clini- cal symptoms with limited tissue destruction, minimal blood loss and no significant complications.
This technique presents a useful minimally-invasive modality for the treatment of single level spinal stenosis.
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목 적 : 퇴행성 요추 질환으로 요통, 하지 방사통 및 신경학적인 증세를 호소한 8예에서 고전적인 후방 감압술 및 후방 추체간 유합술의 술식을 최소 절개를 이용하여 치험한 예를 보고하고자 한다.
대상 및 방법 : 8예 중 5예는 퇴행성 척추관 협착증 및 전방전위증이었고 3예는 단순 퇴행성 척추관 협착증이었다. 수술은 후방에서 정중 측방 접근법 으로 양측에 2.5 cm의 절개를 통하여 감압술과 후방 추체간 유합술을 시행하였으며 경피적으로 척추경 나사못과 강봉을 삽입한 후 상하 분절을 압박 후 고정 하였다. 수술 시간 및 실혈량, 수술 후 합병증을 분석하였고 수술 후 임상적인 증상의 변화 및 동통의 정도를 McNab의 기준과 VAS로 분석하 였다.
결 과 : 수술 시간은 평균 172.5분(130-235분), 수술 중 실혈량은 평균 178.1 mL (95-310 mL)로 전례에서 수혈을 시행하지 않았다. 수술 전 하지 방사 통은 현저한 호전을 보였으며 요통은 수술 직후 VAS 10점을 기준으로 수술 후 3일째 평균 3점, 1주째 2점으로 급속한 감소를 보였다. 수술 후 평균 8 개월 최종 추시시 요통은 0.75점을 보였고 5예에서 우수를 3예에서 양호의 결과를 보였다.
결 론 : 최소 절개를 통한 후방 감압술 및 후방 추체간 유합술은 단분절의 척추관 협착증의 수술적 치료에서 고전적인 술식의 모든 술기를 충분히 포 함하면서도 정상적인 조직의 손상을 최소화할 수 있는 좋은 치료 방법이 될 수 있을 것으로 사료되었으며 향후 좀 더 많은 증례를 통한 분석이 필요 할 것이다.
색인 단어 : 최소 절개, 후방 추체간 유합술
최소 절개를 이용한 요추의 후방 감압술 및 후방 추체간 유합술 - 예비 보고 -
김기택∙석경수∙이영호∙김영우*∙이상훈*
경희대학교 의과대학 정형외과학교실, 한림대학교 의과대학 정형외과학교실*
