Paul C. McCormick
Peng-Yuan Chang, Hsuan-Kan Chang and Jau-Ching Wu
Scott A. Meyer, Jau-Ching Wu and Praveen V. Mummaneni
Two common causes of cervical myelopathy include degenerative stenosis and ossification of the posterior longitudinal ligament (OPLL). It has been postulated that patients with OPLL have more complications and worse outcomes than those with degenerative stenosis. The authors sought to compare the surgical results of laminoplasty in the treatment of cervical stenosis with myelopathy due to either degenerative changes or segmental OPLL.
The authors conducted a retrospective review of 40 instrumented laminoplasty cases performed at a single institution over a 4-year period to treat cervical myelopathy without kyphosis. Twelve of these patients had degenerative cervical stenotic myelopathy ([CSM]; degenerative group), and the remaining 28 had segmental OPLL (OPLL group). The 2 groups had statistically similar demographic characteristics and number of treated levels (mean 3.9 surgically treated levels; p > 0.05). The authors collected perioperative and follow-up data, including radiographic results.
The overall clinical follow-up rate was 88%, and the mean clinical follow-up duration was 16.4 months. The mean radiographic follow-up rate was 83%, and the mean length of radiographic follow-up was 9.3 months. There were no significant differences in the estimated blood loss (EBL) or length of hospital stay (LOS) between the groups (p > 0.05). The mean EBL and LOS for the degenerative group were 206 ml and 3.7 days, respectively. The mean EBL and LOS for the OPLL group were 155 ml and 4 days, respectively. There was a statistically significant improvement of more than one grade in the Nurick score for both groups following surgery (p < 0.05). The Nurick score improvement was not statistically different between the groups (p > 0.05). The visual analog scale (VAS) neck pain scores were similar between groups pre- and postoperatively (p > 0.05). The complication rates were not statistically different between groups either (p > 0.05). Radiographically, both groups lost extension range of motion (ROM) following laminoplasty, but this change was not statistically significant (p > 0.05).
Patients with CSM due to either degenerative disease or segmental OPLL have similar perioperative results and neurological outcomes with laminoplasty. The VAS neck pain scores did not improve significantly with laminoplasty for either group. Laminoplasty may limit extension ROM.
Jau-Ching Wu, Wen-Cheng Huang, Hsiao-Wen Tsai, Chin-Chu Ko, Ching-Lan Wu, Tsung-Hsi Tu and Henrich Cheng
The long-term outcome of lumbar dynamic stabilization is uncertain. This study aimed to investigate the incidence, risk factors, and outcomes associated with screw loosening in a dynamic stabilization system.
The authors conducted a retrospective review of medical records, radiological studies, and clinical evaluations obtained in consecutive patients who underwent 1- or 2-level lumbar dynamic stabilization and were followed up for more than 24 months. Loosening of screws was determined on radiography and CT scanning. Radiographic and standardized clinical outcomes, including the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were analyzed with a focus on cases in which screw loosening occurred.
The authors analyzed 658 screws in 126 patients, including 54 women (42.9%) and 72 men (57.1%) (mean age 60.4 ± 11.8 years). During the mean clinical follow-up period of 37.0 ± 7.1 months, 31 screws (4.7%) in 25 patients (19.8%) were shown to have loosened. The mean age of patients with screw loosening was significantly higher than those without loosening (64.8 ± 8.8 vs 59.3 ± 12.2, respectively; p = 0.036). Patients with diabetes mellitus had a significantly higher rate of screw loosening compared with those without diabetes (36.0% vs 15.8%, respectively; p = 0.024). Diabetic patients with well-controlled serum glucose (HbA1c ≤ 8.0%) had a significantly lower chance of screw loosening than those without well-controlled serum glucose (28.6% vs 71.4%, respectively; p = 0.021). Of the 25 patients with screw loosening, 22 cases (88%) were identified within 6.6 months of surgery; 18 patients (72%) had the loosened screws in the inferior portion of the spinal construct, whereas 7 (28%) had screw loosening in the superior portion of the construct. The overall clinical outcomes at 3, 12, and 24 months, measured by VAS for back pain, VAS for leg pain, and ODI scores, were significantly improved after surgery compared with before surgery (all p < 0.05). There were no significant differences between the patients with and without screw loosening at all evaluation time points (all p > 0.05). All 25 patients with screw loosening were asymptomatic, and in 6 (24%) osseous integration was demonstrated on later follow-up. Also, there were 3 broken screws (2.38% in 126 patients or 0.46% in 658 screws). To date, none of these loosened or broken screws have required revision surgery.
Screw loosening in dynamic stabilization systems is not uncommon (4.7% screws in 19.8% patients). Patients of older age or those with diabetes have higher rates of screw loosening. Screw loosening can be asymptomatic and presents opportunity for osseous integration on later follow-up. Although adverse effects on clinical outcomes are rare, longer-term follow-up is required in cases in which screws become loose.
Jau-Ching Wu, Wen-Cheng Huang, Tsung-Hsi Tu, Hsiao-Wen Tsai, Chin-Chu Ko, Ching-Lan Wu and Henrich Cheng
Cervical arthroplasty is a valid option for patients with single-level symptomatic cervical disc diseases causing neural tissue compression, but postoperative heterotopic ossification (HO) can limit the mobility of an artificial disc. In the present study the authors used CT scanning to assess HO formation, and they investigated differences in radiological and clinical outcomes in patients with either a soft-disc herniation or spondylosis who underwent cervical arthroplasty.
Medical records, radiographs, and clinical evaluations of consecutive patients who underwent single-level cervical arthroplasty were reviewed. Arthroplasty was performed using the Bryan disc. The patients were divided into a soft-disc herniation group and a spondylosis group. Clinical outcomes were measured using the visual analog scale (VAS) for neck and arm pain and the Neck Disability Index (NDI), whereas HO grading was determined by studying CT scans. Radiological and clinical outcomes were analyzed, and the minimum follow-up duration was 24 months.
Forty-seven consecutive patients underwent a single-level cervical arthroplasty. Forty patients (85.1%) had complete radiological evaluations and clinical follow-up of more than 2 years. Patients were divided into 1 of 2 groups: soft-disc herniation (16 cases) and the spondylosis group (24 cases). Their mean age was 45.51 ± 11.12 years. Sixteen patients (40%) were female. Patients in the soft-disc herniation group were younger than those in the spondylosis group, but the difference was not statistically significant (42.88 vs 47.26, p = 0.227). The mean follow-up duration was 38.83 ± 9.74 months. Sex, estimated blood loss, implant size, and perioperative NSAID prescription were not significantly different between the groups (p = 0.792, 0.267, 0.581, and 1.000, respectively). The soft-disc herniation group had significantly less HO formation than the spondylosis group (1 HO [6.25%] vs 14 Hos [58.33%], p = 0.001). Almost all artificial discs in both groups remained mobile (100% and 95.8%, p = 0.408). The clinical outcomes were not significantly different between the groups at all postoperative time points of evaluation, and clinical improvements were also similar.
Clinical outcomes of single-level cervical arthroplasty for soft-disc herniation and spondylosis were similar 3 years after surgery. There was a significantly higher rate of HO formation in patients with spondylosis than in those with a soft-disc herniation. The mobility of the artificial disc is maintained, but the long-term effects of HO and its higher frequency in spondylotic cases warrant further investigation.
Tsung-Hsi Tu, Jau-Ching Wu, Wen-Cheng Huang, Ching-Lan Wu, Chin-Chu Ko and Henrich Cheng
Heterotopic ossification (HO) after cervical arthroplasty can limit the mobility of an artificial disc. In this study the authors used CT scanning to assess the formation of HO with the goal of investigating the correlation between the carpentry of arthroplasty, formation of HO, mobility, and clinical outcomes.
A retrospective review of medical records, radiological studies, and clinical evaluations was conducted for consecutive patients who underwent 1- or 2-level cervical arthroplasty with the Bryan disc. The patients underwent follow-up for more than 24 months. The formation of HO was assessed using CT scanning as the final determination. The perfectness of carpentry for each arthroplasty level was scrutinized using criteria composed of 2 parameters (postoperative shell kyphosis and inadequate endplate coverage). Levels were divided into the optimal carpentry group and the suboptimal carpentry group. Radiographic and clinical outcomes, including the visual analog scale and neck disability index, were compared between the groups.
A total of 107 levels of Bryan discs were placed in 75 patients (mean age 46.71 ± 9.94 years) and were analyzed. There was a male predominance of 68.0% (51 men), and the mean follow-up duration was 38.56 ± 9.66 months. Heterotopic ossification was identified in 60 levels (56.1%) by CT scanning. Most cases of HO were low grade and did not correlate with the limitation in the segmental motion of the arthroplasty device. There were no significant differences in terms of age, sex, and number of arthroplasty levels between the optimal and the suboptimal carpentry groups. However, the suboptimal carpentry group had significantly more high-grade HO (≥ Grade 2) than the optimal carpentry group (13 levels [12.1%] vs 7 levels [6.5%], p = 0.027). There were also more immobile (range of motion < 3°) artificial discs in the suboptimal carpentry group than the optimal carpentry group (11 levels [10.3%] vs 4 levels [3.7%], p = 0.010). The clinical outcomes (neck and arm visual analog scale scores and Neck Disability Index) in both groups were similarly good.
Shell kyphosis and inadequate endplate coverage have adverse effects on the formation of HO and segmental mobility after cervical arthroplasty with the Bryan artificial disc. Appropriate carpentry is the more important factor in determining the maintenance of segmental motion. Although the midterm clinical outcome remained similarly good regardless of HO, the carpentry of cervical arthroplasty should not be overlooked. Further studies are needed to clarify the etiology of HO.
Recent advances in the management of cervical spondylotic myelopathy: bibliometric analysis and surgical perspectives
JNSPG 75th Anniversary Invited Review Article
Yu-Chun Chen, Chao-Hung Kuo, Chieh-Ming Cheng and Jau-Ching Wu
Cervical spondylotic myelopathy (CSM) has become a prevalent cause of spinal cord dysfunction among the aging population worldwide. Although great strides have been made in spine surgery in past decades, the optimal timing and surgical strategy to treat CSM have remained controversial. In this article the authors aimed to analyze the current trends in studies of CSM and to summarize the recent advances of surgical techniques in its treatment.
The PubMed database was searched using the keywords pertaining to CSM in human studies that were published between 1975 and 2018. Analyses of both the bibliometrics and contents, including the types of papers, authors, affiliations and countries, number of patients, and the surgical approaches were conducted. A systematic review of the literature was also performed with emphasis on the diagnosis and treatment of mild CSM.
A total of 1008 papers published during the span of 44 years were analyzed. These CSM studies mainly focused on the natural history, diagnosis, and treatment, and only a few prospective randomized trials were reported. For the authors and affiliations, there was a shift of clustering of papers toward Asian countries in the past decades. Regarding the treatment for CSM, there was an exponential growth of surgical series published, and there was a trend toward slightly more anterior than posterior approaches through the past decade. Patients with CSM had increased risks of neurological deterioration or spinal cord injury with nonoperative management. Because surgery might reduce the risks, and early surgery was likely to be correlated with better outcomes, there was a trend toward attention to mildly symptomatic CSM.
There is emerging enthusiasm for research on CSM worldwide, with more publications originating in Asian countries over the past few decades. The surgical management of CSM is evolving continuously toward early and anterior approaches. More prospective investigations on the optimal timing and choices of surgery are therefore needed.
Matthew B. Potts, Jau-Ching Wu, Nalin Gupta and Praveen V. Mummaneni
Symptomatic tethered cord and associated anomalies such as diastematomyelia rarely present during adulthood but can cause significant pain as well as motor, sensory, and bladder dysfunction. As with children, studies have shown that surgical detethering may provide improvement in pain and neurological deficits. Typical surgical management involves an open laminectomy, sectioning of the filum terminale, and exploration of the split cord malformation. Such open approaches, however, cause significant paraspinous muscle trauma and scarring. Recent advances in minimally invasive techniques allow for access to the spine and thecal sac while minimizing associated muscular trauma. The authors present a comparison of open versus minimally invasive surgery to treat adult tethered cord syndrome.
Six adult patients underwent surgical release of a tethered spinal cord (2 of them also had diastematomyelia). The mean age of the patients was 47.78 years (range 31–64 years). All medical records and images were retrospectively reviewed. Three of the patients underwent traditional open laminectomies for detethering (open group) while the other 3 patients underwent minimally invasive (mini-open) spinal cord detethering. The length of the incision, length of stay, estimated blood loss, and complications were compared between the 2 groups.
All 6 patients had tethered spinal cords, and 1 patient in each group had diastematomyelia. The mean estimated blood loss during surgery (300 ml in the open group vs 167 ml in the mini-open group, p = 0.313) and the mean length of stay (7 days in the open group vs 6.3 days in the mini-open group, p = 0.718) were similar between the 2 groups. The incision length was half as long in the mini-open group versus the open group. However, 1 patient in the mini-open group developed a postoperative pseudomeningocele requiring surgical revision, whereas the open group had no revision surgeries.
Cases of symptomatic diastematomyelia and tethered cord in adults can be safely and effectively explored through a mini-open approach. In this small case series, the authors did find that the mini-open group had an incision that was 50% smaller than the open group, but they did not find a significant clinical difference between the groups.
Jason S. Cheng, Cheerag Upadhyaya, Jau-Ching Wu, Tsung-Hsi Tu and Praveen V. Mummaneni
Minimally invasive surgical (MIS) approaches have gained popularity in many surgical fields. Potential advantages to a minimally invasive, spinal intradural approach include decreased operative blood loss, shorter hospitalization, and less post-operative pain. Potential disadvantages include longer operative times, decreased exposure, and difficulty closing the dura. Prior case series from our group and others have demonstrated successful tumor resections using MIS techniques without increased complications. In this 3D video, we demonstrate the key steps in our mini-open, transpinous approach for the resection of an intradural, extramedullary lumbar schwannoma. This operation is performed through a midline incision confined to one or two levels. The spinous process is removed. The paraspinal muscles are spread using a series of sequentially larger tubular dilators, and the first dilator is placed in the space previously occupied by the target level spinous process. The expandable tube retractor is then placed over the largest dilator and docked into place over the target laminae. The expandable tubular retractor is 6 centimeters in depth and 2.5 centimeters in width before expansion and is adjustable to 9 centimeters in depth and 4–5 centimeters in diameter which allows removal of intradural lesions confined to one or two spinal segments.
The video can be found here: http://youtu.be/l_C4VruKYng.