Chin-Chu Ko

Screw loosening in the Dynesys stabilization system: radiographic evidence and effect on outcomes

OBJECT Dynamic stabilization systems are used to stabilize degenerative lumbar spondylosis. Loosening of the pedicle screws in such nonfusion implants is predictable. This retrospective study evaluated the incidence of screw loosening and its effect on clinical outcomes. METHODS Charts, radiographic films, and medical records of 71 consecutive patients who underwent decompression using Dynesys dynamic stabilization for 1- or 2-level lumbar spondylosis were reviewed. Radiographic films were evaluated and compared to detect screw loosening. A visual analog scale (VAS) for back pain and the Oswestry Disability Index (ODI) were used for measuring clinical outcome. Statistical analysis was conducted using the chi-square test and Student t-test. RESULTS The 71 patients in the study sample had a mean age of 59.2 +/- 11.65 years (range 23-80 years), with slight female predominance (39 women, 32 men). The mean follow-up duration was 16.6 months (range 8-29 months). There were loose screws in 14 of 71 patients (19.7%), for a rate of 4.6% per screw (17 of 368 screws). Most screw loosening occurred in patients >/= 55 years old (13 of 14 patients) although age and sex had no effect on screw loosening (p = 0.233 and 0.109, respectively). Both the loose screw and solid screw groups experienced significant improvement after the surgery in VAS and ODI scores. On the VAS, scores improved from 5.9 +/- 2.99 to 2.1 +/- 2.14 in the loose screw group (p = 0.003), and from 5.7 +/- 3.45 to 2.9 +/- 2.68 in the solid screw group (p < 0.001). For the ODI scale, scores improved from 43.5 +/- 16.78% to 28.0 +/- 18.18% (p = 0.006) in the loose screw group, and from 52.1 +/- 20.92% to 24.6 +/- 19.78% (p < 0.001) in the solid screw group. There were no significant differences between the 2 groups (p = 0.334 for VAS, p = 0.567 for ODI). CONCLUSIONS The preliminary study of this pedicle-based dynamic stabilization device for 1- and 2-level lumbar spondylosis shows radiographic evidence of screw loosening in 19.7% of patients and 4.6% of screws. Nonetheless, the loosening of screws has no adverse effect on clinical improvement.

Pedicle screw loosening in dynamic stabilization: incidence, risk, and outcome in 126 patients

OBJECT 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

The Incidence of Adjacent Segment Disease Requiring Surgery After Anterior Cervical Diskectomy and Fusion: Estimation Using an 11-Year Comprehensive Nationwide Database in Taiwan

BACKGROUND The incidence of symptomatic adjacent segment disease (ASD) after anterior cervical diskectomy and fusion (ACDF) was reported as 2.9%/y in a previous cohort of 374 patients. Few other data corroborate the incidence and natural history of ASD. OBJECTIVE To calculate the incidence of ASD after ACDF that required secondary fusion surgery. METHODS The retrospective study used an 11-year nationwide database to analyze the incidences. All patients who underwent ACDF for cervical disk diseases were identified through diagnostic and procedure codes. Kaplan-Meier and Cox regression analyses were performed. RESULTS From 1997 to 2007, covering 241 800 725.8 person-years, 19 385 patients received ACDF and 568 had ≥ 2 ACDF operations. The incidence of secondary ACDF operations was 7.6 per 1000 person-years. At the end of the 10-year cohort, 94.4% of patients who had received 1 ACDF remained free from secondary ACDF. The average time interval between the first and second ACDF was 23.3 months. After adjustment for comorbidities and socioeconomic status, secondary ACDF operations were more likely performed on male patients (hazard ratio = 1.27; P = .008) 15 to 39 years of age (hazard ratio = 1.45; P = .009) and 40 to 59 years of age (hazard ratio = 1.41, P = .002, respectively). CONCLUSION Repeat ACDF surgery for ASD cumulated steadily in an annual incidence of approximately 0.8%, much lower than the reported incidence of symptomatic ASD. However, at the end of this 10-year cohort, a considerable portion of patients (5.6%) received a second operation. Younger and male patients are more likely to receive such second operations.

Epidemiology of cervical spondylotic myelopathy and its risk of causing spinal cord injury: a national cohort study

OBJECT This study aimed to determine the age- and sex-specific incidence of cervical spondylotic myelopathy (CSM) and its associated risk of causing subsequent spinal cord injury (SCI). METHODS Using the National Health Insurance Research Database (NHIRD), a 12-year nationwide database in Taiwan, this retrospective cohort study analyzed the incidence of hospitalization caused by CSM. All patients diagnosed with and admitted for CSM were identified during the study period. The CSM patients were divided into 2 groups, a control group and an operated group. An incidence density method was used to estimate age- and sex-specific incidence rates of CSM. The Kaplan-Meier method and Cox regression analyses were performed to compare the risk of SCI between the 2 groups. RESULTS From 1998 to 2009, covering 349.5 million person-years, 14,140 patients were hospitalized for CSM. The overall incidence of CSM-related hospitalization was 4.04 per 100,000 person-years. Specifically, males and older persons had a higher incidence rate of CSM. During the follow-up of these patients for 13,461 person-years, a total of 166 patients were diagnosed with SCI. The incidence of SCI was higher in the control group than the operated group (13.9 vs 9.4 per 1000 person-years, respectively). During the follow-up, SCI was more likely to occur in CSM patients who were treated conservatively (crude HR 1.48, p = 0.023; adjusted HR 1.57, p = 0.011) than in those who underwent surgery for CSM. CONCLUSIONS In a national cohort of eastern Asia, the incidence of CSM-caused hospitalization was 4.04 per 100,000 person-years, with higher incidences observed in older and male patients. Subsequent SCI was more likely to develop in patients who received nonoperative management than in those who underwent surgery. Therefore, patients with CSM managed without surgery should be cautioned about SCI. However, further investigations are still required to clarify the risks and complications associated with surgery for CSM.

Differences between 1- and 2-level cervical arthroplasty: more heterotopic ossification in 2-level disc replacement: Clinical article.

OBJECT The most currently accepted indication for cervical arthroplasty is 1- or 2-level degenerative disc disease (DDD) refractory to medical treatment. However, the randomized and controlled clinical trials by the US FDA investigational device exemption studies only compared cervical arthroplasty with anterior cervical discectomy and fusion for 1-level disease. Theoretically, 2-level cervical spondylosis usually implicates more advanced degeneration, whereas the 1-level DDD can be caused by merely a soft-disc herniation. This study aimed to investigate the differences between 1- and 2-level cervical arthroplasty. METHODS The authors analyzed data obtained in 87 consecutive patients who underwent 1- or 2-level cervical arthroplasty with Bryan disc. The patients were divided into the 1-level and the 2-level treatment groups. Clinical outcomes were measured using the visual analog scale (VAS) for the neck and arm pain and the Neck Disability Index (NDI), with a minimum follow-up of 30 months. Radiographic outcomes were evaluated on both radiographs and CT scans. RESULTS The study analyzed 98 levels of Bryan cervical arthroplasty in 70 patients (80.5%) who completed the evaluations in a mean follow-up period of 46.21 ± 9.85 months. There were 22 females (31.4%) and 48 males (68.6%), whose mean age was 46.57 ± 10.07 years at the time of surgery. The 1-level group had 42 patients (60.0%), while the 2-level group had 28 patients (40.0%). Patients in the 1-level group were younger than those in the 2-level group (mean 45.00 vs 48.93 years, p = 0.111 [not significant]). Proportional sex compositions and perioperative prescription of nonsteroidal antiinflammatory drugs were also similar in both groups (p = 0.227 and p = 1.000). The 2-level group had significantly greater EBL during surgery than the 1-level group (220.80 vs 111.89 ml, p = 0.024). Heterotopic ossification was identified more frequently in the 2-level group than the 1-level group (75.0% vs 40.5%, p = 0.009). Although most of the artificial discs remained mobile during the follow up, the 2-level group had fewer mobile discs (100% and 85.7%, p = 0.022) than the 1-level group. However, in both groups, the clinical outcomes measured by VAS for neck pain, VAS for arm pain, and NDI all significantly improved after surgery compared with that preoperatively, and there were no significant differences between the groups at any point of evaluation (that is, at 3, 6, 12, and 24 months after surgery). CONCLUSIONS Clinical outcomes of 1- and 2-level cervical arthroplasty were similar at 46 months after surgery, and patients in both groups had significantly improved compared with preoperative status. However, there was a significantly higher rate of heterotopic ossification formation and less mobility of the Bryan disc in patients who underwent 2-level arthroplasty. Although mobility to date has been maintained in the vast majority (94.3%) of patients, the long-term effects of heterotopic ossification warrant further investigation.

Multilevel arthroplasty for cervical spondylosis: more heterotopic ossification at 3 years of follow-up.

Study Design. Retrospective cohort study. Objective. To investigate the differences between single- and multilevel degenerative disc diseases (DDDs) treated with cervical arthroplasty. Summary of Background Data. The US Food and Drug Administration clinical trials compared arthroplasty with anterior cervical discectomy and fusion for single-level DDD. However, cervical arthroplasty for multilevel DDD is rarely addressed in the literature. Methods. A total of 102 consecutive patients who underwent Bryan arthroplasty were divided into either a single- or multilevel group. Clinical outcomes were measured by the visual analogue scale (VAS) of neck and arm, and by the neck disability index with a minimum follow-up of 25 months. Every patient had radiographical evaluations, and computed tomography. Results. Eighty-six patients (84.3%) completed the follow-up with a mean time of 38.3 ± 8.7 months. Postoperatively, there were significant improvements in clinical outcomes (i.e., VAS neck, VAS arm, and neck disability index) at each time point of evaluation (i.e., 3-, 6-, 12-, and 24 mo postoperation). The sex composition and clinical outcome improvements between the single- and multilevel groups were not significantly different. The multilevel group was older (51.3 ± 8.6 vs. 46.3 ± 11.2 yr; P = 0.02), had more intraoperative blood loss (218.0 ± 182.4 vs. 102.8 ± 79.2 mL; P = 0.001), and demonstrated a higher rate of heterotopic ossification (HO) than the single-level group (66.0% vs. 25.0%; P < 0.001). The majority (97.7%) of the artificial discs in this series remained mobile despite HO. Conclusion. Clinical outcomes of cervical arthroplasty in multilevel spondylosis are similar to single-level outcomes. However, the significantly higher rate of HO found in multilevel arthroplasty and its long-term effect warrant further investigation.

The effects of carpentry on heterotopic ossification and mobility in cervical arthroplasty: determination by computed tomography with a minimum 2-year follow-up: Clinical article.

OBJECT 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

Differences between soft-disc herniation and spondylosis in cervical arthroplasty: CT-documented heterotopic ossification with minimum 2 years of follow-up.

OBJECT 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

Unilateral salpingo-oophorectomy as fertility-sparing surgery for borderline ovarian tumors

Background: To investigate recurrence rates and fertility outcomes of patients with borderline ovarian tumors (BOTs) treated with fertility‐sparing surgery. Methods: This was a retrospective study. All women with BOTs from 2000 to 2006 were evaluated. Clinical outcomes were compared among groups that underwent radical, unilateral salpingo‐oophorectomy, or ovarian cystectomy. The effects of clinical characteristics on recurrence were analyzed by independent t test, chi‐square test, and Cox proportional hazard model. Results: After a mean follow‐up period of 56.5 months, all 61 patients were alive. Seven (11.5%) had developed disease recurrence, and all were in the fertility‐sparing group. Of these, five were in the cystectomy‐only group and two in the unilateral salpingo‐oophorectomy group. There was significant difference in tumor recurrence rates between the two groups (hazard ratio: 0.26, 95% confidence interval: 0.11–0.61). Nine pregnancies were achieved in six women, resulting in five deliveries Conclusion: Fertility‐sparing surgery is an acceptable and safe option for women with BOTs who wish to preserve fertility. Unilateral salpingo‐oophorectomy must be considered as the first choice.

Arthroplasty for cervical spondylotic myelopathy: similar results to patients with only radiculopathy at 3 years' follow-up.

OBJECT Cervical arthroplasty has been accepted as a viable option for surgical management of cervical spondylosis or degenerative disc disease (DDD). The best candidates for cervical arthroplasty are young patients who have radiculopathy caused by herniated disc with competent facet joints. However, it remains uncertain whether arthroplasty is equally effective for patients who have cervical myelopathy caused by DDD. The aim of this study was to compare the outcomes of arthroplasty for patients with cervical spondylotic myelopathy (CSM) and patients with radiculopathy without CSM. METHODS A total of 151 consecutive cases involving patients with CSM or radiculopathy caused by DDD and who underwent one- or two-level cervical arthroplasty were included in this study. Clinical outcome evaluations and radiographic studies were reviewed. Clinical outcome measurements included the Visual Analog Scale (VAS) of neck and arm pain, Japanese Orthopaedic Association (JOA) scores, and the Neck Disability Index (NDI) in every patient. For patients with CSM, Nurick scores were recorded for evaluation of cervical myelopathy. Radiographic studies included lateral dynamic radiographs and CT for detection of the formation of heterotopic ossification . RESULTS Of the 151 consecutive patients with cervical DDD, 125 (82.8%; 72 patients in the myelopathy group and 53 in the radiculopathy group) had at least 24 months of clinical and radiographic follow-up. The mean duration of follow-up in these patients was 36.4 months (range 24-56 months). There was no difference in sex distribution between the 2 groups. However, the mean age of the patients in the myelopathy group was approximately 6 years greater than that of the radiculopathy group (53.1 vs 47.2 years, p < 0.001). The mean operation time, mean estimated blood loss, and the percentage of patients prescribed perioperative analgesic agents were similar in both groups (p = 0.754, 0.652, and 0.113, respectively). There were significant improvements in VAS neck and arm pain, JOA scores, and NDI in both groups. Nurick scores in the myelopathy group also improved significantly after surgery. In radiographic evaluations, 92.5% of patients in the radiculopathy group and 95.8% of those in the radiculopathy group retained spinal motion (no significant difference). Evaluation of CT scans showed heterotopic ossification in 34 patients (47.2%) in the myelopathy group and 25 patients (47.1%) in the radiculopathy group (p = 0.995). At a mean of over 3 years postoperatively, no secondary surgery was reported in either group. CONCLUSIONS The severity of myelopathy improves after cervical arthroplasty in patients with CSM caused by DDD. At 3-year follow-up, the clinical and radiographic outcomes of cervical arthroplasty in DDD patients with CSM are similar to those patients who have only cervical radiculopathy. Therefore, cervical arthroplasty is a viable option for patients with CSM caused by DDD who require anterior surgery. However, comparison with the standard surgical treatment of anterior cervical discectomy and fusion is necessary to corroborate the outcomes of arthroplasty for CSM.