Treatment of basilar invagination with atlantoaxial dislocation: atlantoaxial joint distraction and fixation with transoral atlantoaxial reduction plate (TARP) without odontoidectomy

Purpose

Although direct transoral decompression and one-stage posterior instrumentation can obtain satisfactory cord decompression for the treatment of basilar invagination with atlantoaxial dislocation, surgical injuries run high as combinative anterior-posterior approaches were necessary. Furthermore, the complications will rise notably when involvement of dens and/or clivus in the decompression necessitates relatively complicated surgical techniques. First initiated in 2005, transoral atlantoaxial reduction plate (TARP) works as an internal fixation for the treatment of basilar invagination with irreducible atlantoaxial dislocation. Therefore, this article aimed to describe several operative experiences about this approach, which has delivered successful decompression, fixation and fusion.

Methods

21 consecutive patients with basilar invagination underwent the TARP operation. The pre- and postoperative medulla-cervical angles were measured and compared. The JOA scores of spinal cord function were calculated pre- and post-operatively. 20 cases (20/21) were followed up to average 12.5 months.

Results

Symptoms of all the 20 cases were relieved in different degrees. The postoperative imaging showed the odontoid processes obtained ideal reduction and the internal fixators were all in good position. The medulla-cervical angle was correctd from an average (± standard deviation) 128.7° + 11.9° (n = 20) before surgery to 156.5° + 8.1° (n = 20) after surgery (P < 0.01). The average preoperative and postoperative Japaneses Orthopedic Association scores were 11.25 (n = 20) and 15.9 (n = 20), respectively, indicating 76 % improvement. Screw-loosening was observed in one patient due to severe osteoporosis. After a revised operation with a TARP in another size, the neurological symptoms showed no obvious improvements. Then the treatment was terminated.

Conclusions

The TARP operation and intra-operative traction could reduce the odontoid process superiorly migrating into the foramen magnum, directly ease the ventral compression of spinal cord, and fix the reduced atlantoaxial joints through a single transoral approach without the need of a posterior operation. In this stury, 21 patients were evaluated and 20 did well with TARP operation. The preliminary clinical result was satisfactory.     

Posterior C1–C2 screw and rod instrument for reduction and fixation of basilar invagination with atlantoaxial dislocation

Purpose

To report the surgical technique and preliminary clinical results for the treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) by posterior C1–C2 pedicle screw and rod instrument.

Methods

Between July 2012 and August 2013, 33 patients who had BI with AAD underwent surgery at our institution. Pre and postoperative three-dimensional computed tomographic (CT) scans were performed to assess the degree of dislocation. Magnetic resonance (MR) imaging was used to evaluate the compression of the medulla oblongata. For all patients, reduction of the AAD was conducted by two steps: fastening nuts and rods was performed to achieve the horizontal reduction. Distraction between C1 and C2 screws was performed to obtain the vertical reduction.

Results

No neurovascular injury occurred during surgery. Follow-up ranged from 6 to 15 months (mean 10.38 months) in 32 patients. Post-operative three-dimensional CT showed that complete horizontal reduction was obtained in 30/33 (90.9 %), and complete vertical reduction was obtained in 31/33 (93.9 %). The repeated three-dimensional CT and MR image demonstrated that bony fusion and the decompression of the medulla oblongata were obtained in all patients. Clinical symptoms improved significantly 3 months after surgery.

Conclusions

This C1–C2 pedicle screw and rod instrument is a promising technique for the treatment of BI with AAD.     

Syndromic versus nonsyndromic atlantoaxial dislocation: do clinico-radiological differences have a bearing on management?

Background

This prospective study attempts to study the clinico-radiological differences between patients with syndromic AAD (SAAD), non-syndromic AAD (NSAAD), and AAD with Klippel–Feil anomaly (AADKFA) that may impact management.

Methods

In 46 patients with AAD [SAAD (including Morquio, Down, Larson and Marshall syndrome and achondroplasia; n?=?6); NSAAD(n?=?20); and, AADKFS (n?=?20)], myelopathy was graded as mild (n?=?17, 37 %), moderate (15, 32.5 %) or severe (14, 30.5 %) based on Japanese Orthopaedic Association Score modified for Indian patients (mJOAS). Basilar invagination (BI), basal angle, odontoid hypoplasia, facet-joint angle, effective canal diameter, Ishihara curvature index, and angle of retroversion of odontoid and vertebral artery (VA) variations were also studied.

Statistics

Clinico-radiological differences were assessed by Fisher’s exact test, and mean craniometric values by Kruskal–Wallis test (p value ≤?0.05 significant)

Results

Incidence of irreducible AAD in SAAD (n?=?0), NSA AD (11.55 %) and AADKFS (n?=?18.90 %) showed significant difference (p?=?0.01). High incidence of kyphoscoliosis (83 %) and odontoid hypoplasia (83 %) in SAAD, and assimilated atlas and BI in NSAAD and AADKFA groups were found. In AADKFA, effective canal diameter was significantly reduced(p?=?0.017) with increased Ishihara index and increased angle of odontoid retroversion; 61 % patients had VA variations. Thirty-five patients underwent single-stage transoral decompression with posterior fusion (for irreducible AAD) or direct posterior stabilization (for reducible AAD). Postoperative mJOAS evaluation often revealed persistent residual myelopathy despite clinical improvement.

Conclusions

Myelopathy is induced by recurrent cord trauma due to reducible AAD in SAAD, and compromised cervicomedullary canal diameter in NSAAD and AADKFA. SAAD in children may be missed due to incomplete odontoid ossification or coexisting angular deformities. In AADKFA, decisions regarding vertebral levels to be included in posterior stabilization should take into consideration intact intervening motion segments and compensatory cervical hyperlordosis. Following VA injury, endovascular primary vessel occlusion/stenting across pseudoaneurysm preempts delayed rehemorrhage.     

颅底凹陷症伴寰枢椎脱位后路术后TARP翻修

目的评价经口寰枢椎复位钢板(TARP)内固定在颅底凹陷症伴寰枢椎脱位后路减压术后翻修手术中的应用价值。方法 2008年9月至2012年6月广州军区广州总医院采用TARP内固定翻修手术治疗30例颅底凹陷症伴寰枢椎脱位后路减压术后症状无改善或加重的患者。通过手术前后颈椎过伸过屈位X线片、上颈椎CT扫描及三维重建、MRI检查观察寰枢椎脱位和颈脊髓压迫改善情况,根据日本骨科学会(JOA)评分标准评估患者术后神经功能恢复情况。结果所有翻修手术成功完成,手术时间120~250 min,平均手术时间150 min;术中出血量50~200 mL,平均出血量120 mL。随访6~39个月,平均随访时间16个月。30例患者寰枢椎脱位均获得满意减压复位,脊髓压迫完全解除,术后3~6个月均达到骨性愈合。寰齿间隙从术前的(9.1±1.4)mm降至术后的(1.6±1.4)mm,颈髓角从术前(116.5±12.0)°提高到术后(149.3±10.4)°,手术前后比较,差异有统计学意义(t=18.842,P=0.000;t=—16.520,P=0.000)。29例神经功能获得改善、1例无变化;JOA评分由术前的(10.8±2.3)分提高至术后6个月的(14.5±1.9)分,手术前后比较,差异有统计学意义(t=—17.440,P=0.000)。随访期内无寰枢椎再次脱位或症状加重表现;1例术后2周出现肺部感染,术后1个月枢椎螺钉松动,予抗感染治疗及螺钉调整术后痊愈出院。结论 TARP内固定是颅底凹陷症伴寰枢椎脱位安全有效的治疗方式之一,对于后路减压术后内固定及植骨融合困难的翻修病例具有较好的应用价值。     

Radiographic and clinical assessment on the accuracy and complications of C1 anterior lateral mass and C2 anterior pedicle screw placement in the TARP-III procedure: a study of 106 patients

Purpose

To investigate the (1) radiographic and clinical accuracy of C1 anterior lateral mass screw (C1ALMS) and C2 anterior pedicle screw (C2APS) placement in the transoral atlantoaxial reduction plate (TARP)-III procedure, (2) screw insertion-associated clinical complications and (3) fusion status between C1 and C2.

Methods

Radiographic and clinical data were obtained from the electronic medical record system. Studies were carried out to assess the accuracy of C1ALMS and C2APS placement, the screw insertion-associated clinical complications and the fusion status between C1 and C2. Placement of the screws was assessed using the modified All India Institute of Medical Sciences outcome-based classification.

Results

Two-hundred and twelve C1ALMS and 207 C2APS in 106 patients were assessed. The ideal accurate rates were 92.0 % (195) and 53.1 % (110), and the acceptable accurate rates were 97.6 % (207) and 87.0 % (180), respectively. One patient died postoperatively due to C2 screw misplacement. There were no symptoms of neurologic and vertebral artery injuries in the rest of the patients. 102 patients (97.1 %) achieved solid fusion between C1 and C2. No instrumentation failure due to delayed union or nonunion was observed.

Conclusion

C1ALMS placement in TARP-III procedures appears to be safe. The cortical breach rate of C2APS is high though clinically the neurovascular complication rate is similar to that of posterior atlantoaxial procedures. Advanced navigation strategies may help improve the accuracy of C2APS placement and decrease potential complications.     

Cervical curvature, spinal cord MRIT2 signal, and occupying ratio impact surgical approach selection in patients with ossification of the posterior longitudinal ligament

Objective

Factors impacting surgical options and outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) were explored.

Methods

A retrospective analysis was conducted of 127 eligible cervical OPLL patients (61 males, 66 females) aged 41–70 years (mean 55.2 years) selected from 152 total OPLL patients treated from 2002 to 2006, with 5–10-year (mean 6.8 years) follow-up. Patients underwent anterior subtotal corpectomy with ossification ligament resection (anterior surgery, n = 68) or posterior cervical double-door laminoplasty (posterior surgery, n = 59). Radiographic assessments of cervical curvature, T2-weighted MRI (MRIT2) signal, and OPLL occupying ratio were correlated with surgical strategy before surgery and at 1, 5 weeks, and 5 years.

Results

Lordosis increased following anterior surgery, though kyphosis improved by 10.3 %. The canal stenosis occupying ratio was >50 %, and short-term improvement following anterior surgery was significantly higher than posterior surgery (P > 0.0001). Superior neurological function was observed in patients with unchanged versus high spinal MRIT2 signals (P = 0.0434). No significant differences were observed in short-term outcomes between anterior and posterior surgeries in high spinal MRIT2 signal patients, but anterior surgery produced significantly better long-term outcomes at 1 week (P = 0.7564) and 1 year (P = 0.0071). Complications occurred in five anterior and three posterior surgeries.

Conclusion

Preoperative assessment of cervical curvature, MRIT2 signal, and occupying ratio can be used to guide clinical surgical approach selection to potentially produce better long-term outcomes in patients with OPLL.     

Implantation of the anterior atlantoaxial lateral mass intervertebral cage using the transoral approach

Background

The purpose of this study was to evaluate the possibility of implanting the anterior atlantoaxial lateral mass intervertebral cage, a new type of fixation, by the transoral approach.

Neurological recovery after posterior decompression surgery for anterior dural compression in paralytic spinal metastasis

Purpose

Paralysis in spinal metastasis is often caused by anterior dural compression, and anterior approach has been frequently chosen for decompression despite its dreadful complications. On the other hand, the effectiveness of posterior indirect decompression has not specifically established. The objective of the present study was to investigate the anatomical patterns of dural compression, and to clarify the effectiveness of posterior surgery for anterior lesions.

Methods

We retrospectively analyzed the anatomical patterns of spinal metastasis on MRI images and the neurological recovery in the paralytic patients who underwent posterior decompression and fusion surgery with intraoperative radiation therapy. The recovery rate was compared between those with an anterior or circumferential dural compression (A+), who were indirectly decompressed, and those with a posterior and/or lateral dural compression (A?), who were directly decompressed.

Results

A total of 135 cases were included in the study, and 81.5% had anterior dural compression (A+). In the A+ group, 88.2% of preoperatively non-ambulatory cases regained the gait. Full recovery was achieved in 50% of preoperatively ambulatory cases. These rates were not significantly different from those in the A? group. The rate of gait regain was diminished in the surgeries of the middle thoracic spine (T5-8).

Conclusions

Most spinal metastases cause paralysis by anterior compression; however, the result of posterior indirect decompression was similar to that of posterior direct decompression, although kyphosis negatively affected the result. Anterior decompression might not always be necessary for soft tumor compression as long as the adjuvant therapy is effective for the local control.     

Analysis of intraoperative difficulties and management of operative complications in revision anterior exposure of the lumbar spine: a report of 25 consecutive cases

Purpose

After a first anterior approach to the lumbar spine, formation of adhesions of soft tissues to the spine increases the surgical difficulties and potential for iatrogenic injury during the revision exposure. The objective of this study was to identify the intraoperative difficulties and postoperative complications associated with revision anterior lumbar spine procedures in a single institution.

Methods

This is a retrospective review of 25 consecutive anterior revision lumbar surgeries in 22 patients (7 men and 15 women) operated on between 1998 and 2011. Patients with trauma or malignancies were excluded. The mean age of the patients at the time of revision surgery was 56 years (range 20–80 years). The complications were analyzed depending on the operative level and the time between the index surgery and the revision.

Results

Six major complications (five intraoperatively and one postoperatively) occurred in five patients (20 %): three vein lacerations (12 %) and two ureteral injuries (8 %), despite the presence of a double-J ureteral stent. The three vein damages were repaired or ligated by a vascular surgeon. One of the two ureteral injuries led to a secondary nephrectomy after end-to-end anastomosis failure; the other necessitated secondary laparotomy for small bowel obstruction.

Conclusions

Anterior revision of the lumbar spine is technically challenging and is associated with a high rate of vascular or urologic complications. Therefore, the potential complications of the procedure must be weighted against its benefits. When iterative anterior lumbar approach is mandatory, exposure should be performed by an access surgeon in specialized centers that have ready access to vascular and urologic surgeons.     

Reduction techniques in the management of atlantoaxial subluxation

Background:

The traditional approach to atlantoaxial subluxation which is irreducible after traction is transoral decompression and reduction or odontoid excision and posterior fixation. Transoral approach is associated with comorbidities. However using a posterior approach a combination of atlantoaxial joint space release and a variety of manipulation procedures, optimal or near optimal reduction can be achieved. We analysed our results in this study based on above procedure.

Materials and Methods:

66 cases treated over a 5 year period were evaluated retrospectively. Three cases treated by occipito cervical fusion were not included in the study. The remaining 63 cases were classified into three types. All except two cases were subjected to primary posterior C1-C2 joint space dissection and release followed by on table manipulation which was tailored to treat the type of atlantoaxial subluxation. Optimal or near optimal reduction was possible in all cases. An anterior transoral decompression was needed only in two cases where a bony growth (callus) between the C1 anterior arch and the odontoid precluded reduction by posterior manipulation. All cases then underwent posterior fusion and fixation procedures. Patients were neurologically and radiologically evaluated at regular followups to assess fusion and stability for a minimum period of 6 months.

Results:

Of the 63 cases who underwent posterior manipulation, 49 cases achieved optimum reduction and the remaining 14 cases showed near optimal reduction. Two cases expired in the postoperative period. None of the remaining cases showed neurological worsening after the procedure. Evaluation at 6 months after surgery revealed good stability and fusion in all except three cases.

Conclusion:

Atlantoaxial joint release and manipulation can be used to achieve reduction in most cases of atlantoaxial subluxation, obivating the need of transoral odontoid excision.     

经口前路寰枢椎复位钢板系统治疗先天性枕颈交界区畸形

目的探讨经口前路寰枢椎复位钢板（transoral atlantoaxial reduction plate,TARP）系统用于先天性枕颈交界区畸形手术治疗的临床疗效。方法 2007年12月-2011年12月采用TARP系统治疗先天性枕颈交界区畸形患者35例。所有患者术前术后均行颈椎过伸过屈位X线、枕颈交界区CT扫描及MRI以评估局部畸形及颈脊髓腹侧压迫情况;采用日本骨科学会（Japanese Orthopaedic Association,JOA）评分（17分法）评估术前术后脊髓损伤及恢复情况。术后3、6、12个月复查颈椎正侧位X线片及CT,评价内固定效果及融合情况。结果 35例患者均顺利完成手术,术后MRI示颈脊髓腹侧压迫均有明显减轻,延髓脊髓角术后平均增加约29.7°,31例（89%）患者术后神经功能有明显改善,4例术前术后神经功能无变化。术后随访1年未发现寰枢椎再脱位、螺钉松动、断裂或移位等并发症。结论TARP系统可对先天性枕颈交界区畸形合并腹侧颈脊髓压迫进行一期减压、复位及内固定,是枕颈交界区畸形理想的治疗手段之一。     

Thoracoscopic interbody fusion with percutaneous posterior stabilization for thoracic and thoracolumbar injuries

Background context

Traumatic thoracolumbar discoligamentous injuries and partial burst fractures are commonly managed through posterior-only stabilization. Many cases present later with failure of posterior implant and progressive kyphotic deformities that necessitates major surgeries. Anterior interbody fusion saves the patients unnecessary long-segment fixation and provides a stable definitive solution for the injured segment.

Purpose

The purpose of this study is to assess the clinical and radiographic outcomes of combined minimal invasive short-segment posterior percutaneous instrumentation and anterior thoracoscopic-assisted fusion in thoracolumbar partial burst fractures or discoligamentous injuries.

Study design

Prospective observational study.

Patient sample

Thirty patients with acute thoracic or thoracolumbar injuries operated upon between December 2007 and January 2009.

Outcome measures

Oswestry Disability Index (ODI), clinical and neurological examination for clinical assessment. Plain X-ray for radiological evaluation.

Methods

Preoperative evaluation included clinical and neurological examination, plain X-rays, computed tomography (CT), and magnetic resonance imaging (MRI). Posterior short-segment percutaneous stabilization plus anterior thoracoscopically assisted fusion in prone position were done. The minimum follow-up period was 2 years (range 24–48 months).

Results

The mean age was 44 years. The commonest affected segment was between T10 and L1 (22 patients, 73 %). The mean total operative time was 103 min. The mean operative blood loss was 444 ml. Interbody fusion cage was used in 28 patients while iliac graft in two cases. Fusion rate at the final follow-up was 97 % (29 patients); one patient did not show definitive fusion although he was clinically satisfied. The mean final follow-up ODI was 12 %. The mean preoperative kyphosis angle was 22° improved to 6.5° postoperatively and was 7.5° at final follow-up. There were no major intraoperative or postoperative complications.

Conclusion

Combined anterior thoracoscopic fusion and short-segment posterior percutaneous instrumentation showed good clinical and radiographic outcomes in cases of thoracolumbar injuries through limiting the instrumented levels and preventing progress of posttraumatic kyphosis.     

Atlantoaxial transarticular screw fixation and posterior fusion using polyester cable: a 10-year experience

Purpose

To retrospective review the clinical outcomes of the modified operative technique using a polyester suture material (Ethibond* Excel) for atlantoaxial transarticular screw fixation and posterior fusion.

Methods

The retrospective reviews were conducted from 2002 to 2012. The patient’s medical record reviews included demographic data, cause of atlantoaxial instability, orthopedic and surgical history, clinical presentation, radiographic finding including plain radiography, complications, operative detail, and outcome of treatment. Fusion of C1–C2 was defined as either graft consolidation or absence of C1–C2 movement on lateral flexion–extension radiograph.

Results

Twenty-three patients demonstrated clinical and radiographic evidence of atlantoaxial instability (13 men and 10 women, with a mean age of 42 years). Majority of atlantoaxial instability was caused by trauma. Most common clinical symptom was neck pain with or without cervical myelopathy. Bilateral screws were placed in 18 of the 23 patients. Five patients underwent placement of unilateral screws. The 13 patients were inserted by screws with diameter 4.0 mm. The means screw length was 40.33 mm. The means of operative time and estimated blood loss were 3.6 h and 234 ml, respectively. The mean of follow-up duration was 18 months. All 41 screws were positioned satisfactorily in C1 lateral mass. All 23 patients achieved fusion (100 % fusion rate). After a period of follow-up, 9 of the 10 neurological deficit patients had completely recovered.

Conclusions

We concluded that the atlantoaxial transarticular screw fixation and posterior fusion using polyester cable can be used for C1–2 fusion with a high fusion rate and less complications in various cases.     

Unstable atlas fracture treatment by anterior plate C1-ring osteosynthesis using a transoral approach

Study design

A retrospective study was conducted to evaluate anterior plate fixation of unstable atlas fractures using a transoral approach.

Objective

To further investigate the safety and efficacy of this surgical technique, as there is currently a paucity of available data.

Summary of background data

While most atlas fractures can be managed by external immobilization with favorable results, surgery is usually preferable in highly unstable cases. Surgical stabilization is most commonly achieved using a posterior approach with fixation of C1–C2 or C0–C2, but these techniques usually result in loss of joint function and cannot fully stabilize anterior arch fractures of the atlas. Although a transoral approach circumvents these issues, only nine cases were described in the literature to our knowledge.

Methods

Twenty patients with unstable atlas fractures were treated with this technique during a 6-year period. Screw and plate placement, bone fusion, and integrity of spinal cord and vertebral arteries were assessed via intraoperative and follow-up imaging. Neurologic function, range of motion, strength, pain levels, and signs of infection were assessed clinically upon follow-up.

Results

There were no incidents of screw loosening or breakage, plate displacement, spinal cord injury, or vertebral artery injury. A total of 20 plates were placed and all 40 screws were inserted into the atlas lateral masses. CT scans demonstrated that two screws were placed too close to the vertebral artery canal, but without clinical consequences. Imaging demonstrated that bone fusion was achieved in all cases by 6 months postoperatively, without intervertebral instability. No plate-related complications were observed in any patients during the follow-up period.

Conclusions

C1 anterior plate fixation using a transoral approach appears to be a safe, reliable, and function-preserving surgical method for the management of unstable atlas fractures. For this type of fracture, a transoral approach with anterior fixation should be considered as an alternative to posterior approaches or conservative treatments.     

Treatment of basilar invagination

Purpose

Basilar invagination is a rare craniocervical malformation which may lead to neurological deficits related to compression of brainstem and upper cervical cord as well as instability of the craniocervical junction. This study presents results of a treatment algorithm developed over a 20-year period focussing on anatomical findings, short-term and long-term outcomes.

Methods

69 patients with basilar invagination (mean age 41 ± 18 years, history 64 ± 85 months) were encountered. The clinical courses were documented with a score system for individual neurological symptoms for short-term results after 3 and 12 months. Long-term outcomes were analyzed with Kaplan–Meier statistics.

Results

Patients with (n = 31) or without (n = 38) ventral compression were distinguished. 25 patients declined an operation, while 44 patients underwent 48 operations. Surgical management depended on the presence of ventral compression and segmentation anomalies between occiput and C3, signs of instability and presence of caudal cranial nerve dysfunctions. 16 patients without ventral compression underwent foramen magnum decompressions without fusion. 19 patients with ventral compression and abnormalities of segmentation or evidence of instability underwent a foramen magnum decompression with craniocervical (n = 18) or C1/2 (n = 1) stabilization. In nine patients with severe ventral compression and caudal cranial nerve deficits, a transoral resection of the odontoid was combined with a posterior decompression and fusion. Within the first postoperative year neurological scores improved for all symptoms in each patient group. In the long-term, postoperative deteriorations were related exclusively to instabilities either becoming manifest after a foramen magnum decompression in three or as a result of hardware failures in two patients.

Conclusions

The great majority of patients with basilar invagination report postoperative improvements with this management algorithm. Most patients without ventral compression can be managed by foramen magnum decompression alone. The majority of patients with ventral compression can be treated by posterior decompression, realignment and stabilization alone, reserving anterior decompressions for patients with profound, symptomatic brainstem compression.     

The impact of surgeon volume on patient outcome in spine surgery: a systematic review

Purpose

Recently, strategies aimed at optimizing provider factors have been proposed, including regionalization of surgeries to higher volume centers and adoption of volume standards. With limited literature promoting the regionalization of spine surgeries, we undertook a systematic review to investigate the impact of surgeon volume on outcomes in patients undergoing spine surgery.

Methods

We performed a systematic review examining the association between surgeon volume and spine surgery outcomes. To be included in the review, the study population had to include patients undergoing a primary or revision spinal procedure. These included anterior cervical discectomy and fusion (ACDF), anterior/posterior cervical fusion, laminectomy/decompression, anterior/posterior lumbar decompression with fusion, discectomy, and spinal deformity surgery (spine arthrodesis).

Results

Studies were variable in defining surgeon volume thresholds. Higher surgeon volume was associated with a significantly lower risk of postoperative complications, a lower length of stay (LOS), lower cost of hospital stay and a lower risk of readmissions and reoperations/revisions.

Conclusions

Findings suggest a trend towards better outcomes for higher volume surgeons; however, further study needs to be carried out to define objective volume thresholds for individual spine surgeries for surgeons to use as a marker of proficiency.

     

Quantification of continuous in vivo flexion–extension kinematics and intervertebral strains

Purpose

Healthy subjects performed lumbar flexion and were assessed by video fluoroscopy to measure the in vivo kinematics of the lower lumbar motion segments.

Methods

Fifteen healthy subjects (8 male, 7 female, 28 ± 10 years) performed lumbar flexion and extension back to neutral while their vertebrae were imaged. The sagittal plane vertebral margins of L3–S1 were identified. Lumbar angle, segmental margin strains, axial displacements, anterior–posterior (A–P) translations, and segmental rotations over the course of flexion were measured.

Results

L4–L5 had the largest posterior margin Green strain (65 %). Each segment displayed more axial displacement than A–P translation. Peak vertebral angulation occurred at approximately 75 % of peak flexion during the extension phase.

Conclusion

L4–L5 exhibited the largest anterior and posterior margin strains (29 and 65 %, respectively). Strains in the disc during in vivo lumbar flexion are due to both angular rotation and linear translation.     

Minimum invasive posterior decompression for cervical spondylotic amyotrophy

Background

Cervical spondylotic amyotrophy (CSA), characterized by amyotrophy and muscular weakness of the upper limbs, is caused by damage to anterior spinal root or anterior horn of the spinal cord. Formerly, anterior decompression and fusion were performed for treatment of CSA, but it has recently been reported that posterior decompression is also effective. However, a consensus on the choice of procedure has not yet been reached. Selective laminoplasty as minimally invasive surgery is a posterior decompression procedure that alleviates axial neck pain. Because, for CSA patients, the responsible lesion level is localized, this procedure combined with foraminotomy enables simultaneous spinal cord and root decompression. Therefore, we report the results of this treatment for CSA.

Methods

Subjects were 28 patients (25 males, 3 females), average age 50.6 years and average follow-up 43.5 months. The muscles involved were deltoid for 14 patients, biceps for 11, and extensor digitorum communis and/or intrinsic muscles of the hand for 9. MMT scores were grade 2 for 23 cases and grade 3 for 5 cases. To evaluate the results of minimally invasive surgery, cervical ROM (C2–7) and postoperative neck pain (VAS) on the first postoperative day and 1 week after surgery were evaluated.

Results

Muscle strength improvement was rated as “excellent” for 18 patients, “good“ for 9, and “fair” for 1, with none rated “poor”. Four of 10 patients whose muscle strength did not fully improve had distal type CSA and/or had preoperative MMT scores of 2. Average %ROM was 91.2 % and almost complete cervical ROM was maintained. The average postoperative VAS score was 2.6 on the first postoperative day and 1.2 1 week after surgery.

Conclusions

Selective laminoplasty with segmental decompression is advantageous for minimizing postoperative neck pain and for simultaneous decompression of the affected spinal cord segment and nerve root.     

Alterations in axial curvature of the cervical spine with a combination of rotation and extension in the conventional anterior cervical approach

Purpose

Alterations of three-dimensional cervical curvature in conventional anterior cervical approach position are not well understood. The purpose of this study was to evaluate alignment changes of the cervical spine in the position. In addition, simulated corpectomy was evaluated with regard to sufficiency of decompression and perforation of the vertebral artery canal.

Methods

Fifty patients with cervical spinal disorders participated. Cervical CT scanning was performed in the neutral and supine position (N-position) and in extension and right rotation simulating the conventional anterior approach position (ER-position). Rotation at each vertebral level was measured. With simulation of anterior corpectomy in a vertical direction with a width of 17 mm, decompression width at the posterior wall of the vertebrae and the distance from each foramen of the vertebral artery (VA) were measured.

Results

In the ER-position, the cervical spine was rotated rightward by 37.2° ± 6.2° between the occipital bone and C7. While the cervical spine was mainly rotated at C1/2, the subaxial vertebrae were also rotated by several degrees. Due to the subaxial rotation, the simulated corpectomy resulted in smaller decompression width on the left side and came closer to the VA canal on the right side.

Conclusions

In the ER-position, the degrees of right rotation of subaxial vertebrae were small but significant. Therefore, preoperative understanding of this alteration of cervical alignment is essential for performing safe and sufficient anterior corpectomy of the cervical spine.     

经口咽前路寰枢椎复位钛板手术在寰枢椎内固定翻修手术中的应用

目的探讨经口咽前路寰枢椎复位钛板(transoral atlantoaxial reduction plate,TARP)手术在寰枢椎内固定翻修手术中的应用价值。方法2005年4月~2007年5月采用自行设计的TARP治疗10例寰枢椎初次手术失败需要再次手术的患者。其中包括寰枢椎脱位,行后路Apofix内固定术后再脱位3例;颅底凹陷症伴寰枢椎脱位,行后路减压枕颈内固定术后寰枢关节仍呈脱位状态且症状加重2例;先天性齿突不连伴寰枢关节脱位,行后路Brooks钛缆寰枢椎内固定术后再脱位且症状加重2例;先天性齿突发育不良伴寰枢关节脱位,行颈前路C1~3 Axis钛板内固定术后未复位且症状加重1例;陈旧性齿突骨折伴寰枢关节脱位行TARP手术后再脱位1例;颅底畸形、C1,2脱位、四肢瘫痪伴呼吸困难,行TARP手术后再脱位1例。10例翻修手术分别为:7例先行后路取出枕颈内固定器及寰枢内固定器,同期行TARP手术;1例行经口前路取出C1~3 Axis钛板,同时行TARP手术;2例行经口前路取出松动的TARP,其中1例更换成比之前小1个型号的TARP和直径比之前粗0.5mm的翻修螺钉予以重新固定,另1例行C2次全切除,更换特制的加长TARP固定于C1侧块和C3椎体。观察翻修术前、术后即时复位及随访时症状、体征、影像学及神经功能恢复情况。结果随访时间为2~25个月,平均18个月。10例寰枢关节脱位均获得解剖复位或接近解剖复位。TARP固定良好,无松动。9例获得骨性融合,1例随访时间偏短,暂无法确定融合情况。MRI示:寰枢节段椎管矢径恢复正常,颈髓获得充分减压,脊髓减压改善率达85%~100%(平均96%),但有3例寰枢节段脊髓明显萎缩,呈高信号改变。7例患者的神经功能获得不同程度的恢复。1例恢复自主呼吸,四肢运动无明显恢复。本组无神经血管损伤和术后再脱位并发症。结论TARP手术对于寰枢椎前后路内固定手术失败的翻修是一个理想的选择。