Sung-Soo Chung

An improvement in sintering property of β-tricalcium phosphate by addition of calcium pyrophosphate

The sintering behavior of calcium pyrophosphate (CPP, Ca2P2O7)-doped beta-tricalcium phosphate [TCP, Ca3(PO4)2], prepared by solid state reaction, was investigated in-situ, using dilatometry. Pure beta-TCP undergoes phase transition to alpha-TCP at about 1200 degrees C; hence pure beta-TCP ceramics should be sintered bclow 1200 degrees C. Pure beta-TCP sintered body can achieve a relative density of only 86% when sintered at 1150 degrees C. However, the addition of CPP in the range of 0.5-3 wt% delays phasc transition of beta-TCP and enables sintering of beta-TCP at 1200 degrees C without a phase transformation to alpha-TCP. Due to this effect of CPP added to TCP, CPP-doped beta-TCP ceramics with relative density over 95% could be obtained when sintered at 1200 degrees C for 2 h.

Ossification of the ligamentum flavum of the thoracic spine in the Korean population

OBJECT Thoracic ossification of the ligamentum flavum (OLF), a main cause of thoracic myelopathy, is an uncommon disease entity. It is seen mostly in East Asia, although the majority of reports have issued from Japan. In the present study, the clinical features and prognostic factors of thoracic OLF were examined in a large number of Korean patients. METHODS Data from 51 consecutive patients who underwent decompressive laminectomy with or without fusion for thoracic OLF between 1998 and 2008 were retrospectively analyzed. Patients were evaluated pre- and postoperatively using the modified Japanese Orthopedic Association (JOA) scale (maximum total score of 11). Patient age, sex, preoperative symptoms, duration of initial symptoms, number of involved segments, duration of follow-up, presence of dural adhesion (dural tearing), intramedullary high signal intensity, morphological classification of OLF (axial or sagittal), coexisting disease, and fusion or no fusion were also evaluated. Surgical outcomes were assessed using JOA recovery rate/outcome scores, and patient satisfaction grades and prognostic factors were analyzed. RESULTS There were 18 men and 33 women with a mean age of 60.9 years (range 38-80 years). A mean preoperative JOA score of 5.5 improved to a mean score of 7.4 at the last follow-up (mean 52 months after surgery). The mean duration of the initial symptoms was 34.5 months (range 0.1-240 months) prior to surgery. The most common symptoms were motor dysfunction (80%); sensory deficit (67%); and pain, numbness, and claudication (59%) in the lower extremities. Knee hyperreflexia appeared in 69% of the patients. There were a total of 130 ossified segments, and the mean number of segments per patient was 2.6. Ninety-two (71%) of 130 segments were located below T-8. Recovery outcomes were good (18 patients), fair (16 patients), unchanged (11 patients), or worse (6 patients). Thirty-one patients (61%) were satisfied with their operations. Patients with a beak type of OLF on sagittal MR images experienced a higher recovery rate and a better satisfaction grade than did those with a round OLF. The patients with higher preoperative JOA scores demonstrated significantly higher JOA scores postoperatively (p < 0.001), and the preoperative JOA score had a significant correlation with the recovery rate in patients exhibiting mainly motor dysfunction (p = 0.040, r = 0.330). CONCLUSIONS Of the thoracic OLF studies published to date, the present analysis involves the largest Korean population. The most common symptoms of thoracic OLF were motor dysfunction and sensory deficit in the lower extremities, although pain, numbness, and claudication were observed in some patients and were notably accompanied by knee hyperreflexia. At a minimum of 2 years after surgery for thoracic OLF, operative outcomes were generally good, and the prognostic factors affecting good surgical outcomes included a beak type of OLF and a preoperative JOA score > 6.

Long-Term Outcomes Following Lumbar Total Disc Replacement Using ProDisc-II: Average 10-Year Follow-Up at a Single Institute.

Study Design. A retrospective analysis. Objective. To evaluate the long-term clinical and radiographic outcomes and to investigate who achieved the successful outcomes after lumbar total disc replacement (TDR) using ProDisc II. Summary of Background Data. There are few evidences regarding the long-term efficacy and safety of TDR. Furthermore, it has not been addressed which patients achieved good outcomes in long-term follow-up. Methods. Data at 1-, 2-, 5-, 7-year, and last follow-up were used for the analysis. According to the presence of combined pathologies, patients were categorized as groups A and B (presumed good and bad candidates, respectively). Clinical outcomes were evaluated using visual analog scale, Oswestry Disability Index, clinical success rate, and subjective satisfaction (four-point scale). Radiographic results included segmental range of motion. Results. Total study population was 54 patients with 69 segments with the average follow-up duration of 120.0 months. There were 39 patients in group A and 15 in group B. Visual analog scale and Oswestry Disability Index scores were improved significantly at all follow-up periods, reaching maximal improvement at the postoperative 2 years. Clinical success rate and satisfaction rate were significantly higher in group A (76.9% and 87.2%, respectively) than those in group B (40.0% and 60.0%, respectively) at the last follow-up. Five patients (9.3%) required revision fusion surgeries, and they are all in group B. The final segmental range of motion was well maintained in monosegmental TDR, but not in bisegmental TDR. Conclusion. Lumbar TDR using Prodisc II showed the successful outcomes with the clinical success rate of 76.9% and the satisfaction rate of 87.2% when the patients were presumed as good candidate for TDR. However, the patients who had the combined pathologies showed suboptimal results with high risk of the revision surgeries. Thus, the strict patient selection process is mandatory for the successful outcomes. Level of Evidence: 4

Comparison of surgical outcomes after cervical laminoplasty: open-door technique versus French-door technique.

Study Design: A retrospective case series. Objective: To compare the surgical outcomes of open-door and French-door cervical laminoplasty for decompressing multilevel cervical spinal cord compressions. Summary of Background Data: Cervical laminoplasty is an effective method for decompressing multilevel cervical spinal cord compressions. Laminoplasty is usually classified as an open-door or French-door technique, but it is still unclear whether laminoplasty affects cervical alignment and clinical outcomes. Methods: Fifty-one patients underwent cervical laminoplasty over a 2-year period for cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, or for a mixed-type condition. The following criteria were evaluated and compared retrospectively for open-door laminoplasty (group A) and French-door laminoplasty (group B): Nurick grades, Japanese Orthopedic Association (JOA) scores, neck disability index, and visual analog scale scores for axial neck pain and radiating pain. During radiologic evaluations, changes in cervical lordotic angles and range of motion were measured at C2–C7. Results: Postoperatively, radiating pain improved significantly in both groups (P<0.05), but axial neck pain was more severe in both groups at last follow-up than preoperatively (P>0.05). Mean neurological improvement was 12.5% according to Nurick grades and 28% according to JOA scores in all study subjects. In particular, the mean Nurick grades showed significant improvement in group A (P<0.05), and the recovery rate was higher in group A than in group B according to Nurick grades (23.5% vs. 6.3%; P<0.05) and JOA scores (44.4% vs. 13%; P<0.05). In contrast, radiologically, cervical lordotic angle and range of motion were more significantly decreased in group B (P<0.05). Conclusions: Although open-door and French-door laminoplasty techniques were found to be effective for treating cervical compressive myelopathy, the open-door technique seems to be superior with respect to clinical and radiologic outcomes.

Changes of upper thoracic curve and shoulder balance in thoracic adolescent idiopathic scoliosis treated by anterior selective thoracic fusion using VATS.

Study Design A retrospective radiographic analysis. Objectives To evaluate changes of upper thoracic curve and shoulder balance in thoracic adolescent idiopathic scoliosis patients treated by anterior selective thoracic fusion using video-assisted thoracoscopic surgery and to identify adequacy of earlier criteria of double thoracic (DT) curve for anterior correction. Summary of Background Data Although anterior and posterior scoliosis correction show many differences in correction mechanisms, fusion levels, loss of correction etc., the criteria of DT curve was applied without differences. There are no reports about these differences. Materials and Methods Forty patients were followed for a minimum of 3 years (range, 3-8 y). The magnitude and flexibility of upper thoracic, lower thoracic, and the superior portion of the lower thoracic curve were measured using full length standing and side-bending radiographs before surgery, at 1 week postoperatively, and at last follow-up. The correction rate and loss of correction of these curves were calculated and preoperative and postoperative radiographic shoulder heights (RSHs) were measured. RSH was defined as balanced (shoulder height difference <10 mm), mildly imbalanced (10-20 mm), or moderately imbalanced (>20 mm). T1 tilt and coronal balance were also evaluated. Patients were divided into groups based on these factors and postoperative RSH was compared. Results Flexibility of the upper thoracic curve was 46% and magnitude of the upper thoracic curve was corrected spontaneously from 28.6±7.8 degrees to 17.9±7.0 degrees with a 37.4% correction rate that did not change during follow-up. On average, preoperative left shoulder was 6.3±10.5 mm lower than right shoulder and this changed to 10.4±11.8 mm and 6.0±8.2 mm higher than right shoulder at 1 week postoperatively and at last follow-up, respectively. The group with an upper thoracic curve of ≥30 degrees or a superior portion of the lower thoracic curve of ≥30 degrees preoperatively had a higher left shoulder postoperatively (P=0.016, 0.040). Of the 12 patients with a symmetric or higher left shoulder (≥0 mm) preoperatively, 9 patients had a balanced shoulder (−10-10 mm) and 3 patients showed mild shoulder imbalance (<20 mm) at last follow-up. Conclusions Among patients who have DT curve, patients with mild left shoulder elevation (<20 mm) can be treated by anterior correction unless the magnitude of upper thoracic curve or superior portion of lower thoracic curve are ≥30 degrees. For anterior correction, criteria of DT curve might be applied less strictly.

Analysis of the predictive role and new proposal for surgical strategies based on the modified Tomita and Tokuhashi scoring systems for spinal metastasis

BackgroundWe sought to identify preoperative factors significantly correlated with survival. We also aimed to evaluate the validity of the prognostic scores in the Tomita and Tokuhashi systems and discuss several aspects to improve the predictive accuracy of these systems. Moreover, we suggest modified criteria for selecting treatment strategies.MethodsIn total, the outcomes of 112 patients with spinal metastasis who underwent surgery between January 2006 and June 2011 were retrospectively reviewed. The validity of the prognostic scores was assessed on the basis of their correlation with survival. For various primary malignancies, new scoring criteria were applied in each system according to the survival results obtained in this study. Each revised scoring system was adjusted with a similar principle of scoring as described previously. Patient survival according to each preoperative factor was analyzed by the Kaplan-Meier method. The predictive value of each scoring system was evaluated by the log-rank test and Cox regression analysis.ResultsThe interval from the diagnosis of the primary malignancy to that of spinal metastasis (p = 0.023) and the interval from the diagnosis of spinal metastasis to surgery (p = 0.039) were significantly correlated with survival. Regarding Tokuhashi scores, the correlation coefficient was 0.790 before adjustment (p = 0.001) and 0.853 after adjustment (p < 0.001). For Tomita scores, the correlation coefficient was -0.994 (p < 0.001) both before and after adjustment.ConclusionsTomita scores more accurately predicted survival than Tokuhashi scores. It is helpful to evaluate both scoring systems with adjustment for primary malignancy depending on the clinical setting. Patients with Tomita scores less than or equal to 8 and Tokuhashi scores greater than or equal to 6 are recommended to undergo surgical management.

How accurately can tokuhashi score system predict survival in the current practice for spinal metastases?: prospective analysis of 145 consecutive patients between 2007 and 2013.

Study Design: Prospective observational study. Summary of Background Data: Tokuhashi score (TS) system was developed in 1990s and widely used for the prediction of survival in patients with spinal metastases. There were no reports about how accurately TS system predicts survival in the current practice. Objective: To validate the accuracy of TS system using a recent series of the patients with metastatic spinal tumors, focusing on the primary tumor type. Methods: Between January 2007 and March 2013, 145 patients who underwent surgical treatment for metastatic spinal tumors were followed up prospectively. The subjects were divided into 3 prognosis group according to TS system. The actual and predicted survivals were compared with calculate the accuracy rate. Results: The mean age was 60.0 years. There were 96 male and 49 female patients. There are 106 patients in poor prognosis group (A), 30 in intermediate prognosis group (B), and 9 in good prognosis group (C). The overall accuracy to predict the survival time was 57.2%. The accuracy rate was especially poor in breast cancer (44.4%) and rectal cancer (42.9%). Forty-three patients (40.6%) in group A and 9 patients (30.0%) in group B survived longer than predicted. The mean survival time was 8.5, 18.1, and 41.6 months for group A, B, and C, respectively. Patients with rectal cancer showed poor survival profile than expected. Conclusions: The accuracy of TS system was suboptimal (57.2%). The predicted survival time needs to be increased in response to the recent population’s data. The score given to the rectal cancer subgroup should be lowered.

How does back muscle strength change after posterior lumbar interbody fusion

OBJECTIVE There is a lack of evidence of how back muscle strength changes after lumbar fusion surgery and how exercise influences these changes. The aim of this study was to evaluate changes in back muscle strength after posterior lumbar interbody fusion (PLIF) and to measure the effects of a postoperative exercise program on muscle strength and physical and mental health outcomes. METHODS This prospective study enrolled 59 women (mean age 58 years) who underwent PLIF at 1 or 2 spinal levels. To assess the effects of a supervised lumbar stabilization exercise (LSE), the authors allocated the patients to an LSE (n = 26) or a control (n = 33) group. The patients in the LSE group performed the LSEs between 3 and 6 months postoperatively. Back extensor strength, visual analog scale (VAS) scores in back pain, and physical component summary (PCS) and mental component summary (MCS) scores on the 36-Item Short Form Health Survey were determined for the both groups. RESULTS Mean strength of the back muscles tended to slightly decrease by 7.5% from preoperatively to 3 months after PLIF (p = 0.145), but it significantly increased thereafter and was sustained until the last follow-up (38.1%, p < 0.001). The mean back muscle strength was similar in the LSE and control groups preoperatively, but it increased significantly more in the LSE group (64.2%) than in the control group (21.7%) at the last follow-up 12 months after PLIF (p = 0.012). At the last follow-up, decreases in back pain VAS scores were more significant among LSE group patients, who had a pain reduction on average of 58.2%, than among control group patients (reduction of 26.1%) (p = 0.013). The patients in the LSE group also had greater improvement in both PCS (39.9% improvement) and MCS (20.7% improvement) scores than the patients in the control group (improvement of 18.0% and 1.1%, p = 0.042 and p = 0.035, respectively). CONCLUSIONS After PLIF, strength in back muscles decreased until 3 months postoperatively but significantly increased after that period. The patients who regularly underwent postoperative LSE had significantly improved back strength, less pain, and less functional disability at 12 months postoperatively.

Stereotactic ablative body radiotherapy for spinal metastasis from hepatocellular carcinoma: its oncologic outcomes and risk of vertebral compression fracture

Spinal metastases from hepatocellular carcinoma (HCC) require high-dose irradiation for durable pain and tumor control. Stereotactic ablative body radiotherapy (SABR) enables the delivery of high-dose radiation. However, but vertebral compression fracture (VCF) can be problematic. The aim of his study is to evaluate the outcome and risk of VCF after SABR for spinal metastasis from HCC. We retrospectively reviewed 33 lesions in 42 spinal segments from 29 patients who received SABR with 1 fraction (16-20 Gy), or 3 fractions (18-45 Gy) from September 2009 to January 2015. The 1-year local control (LC) rate was 68.3%. Radiographic grade of cord compression (RGCC) was the only independent prognostic factor associated with LC (P = 0.007). The 1-year ultimate LC rate including the outcome of salvage re-irradiation was 87.2%. The pain response rate was 73.3% according to the categories of the International Bone Metastases Consensus Group. The 1-year VCF-free rate was 71.5%. Pre-existing VCF (P < 0.001) and only-lytic change (P = 0.017) were associated with a higher post-SABR VCF rate. One-third of post-SABR VCFs required interventions. SABR for spinal metastases from HCC provided efficacious LC, especially for lesions with RGCC ≤ II, and showed effective and durable pain relief. As VCF after SABR occurred frequently for vertebral segments with pre-existing VCF and only-lytic change, early preventive vertebroplasty is considerable for those high-risk vertebral segments.

Incidence of microbiological contamination of local bone autograft used in posterior lumbar interbody fusion and its association with postoperative spinal infection.

OBJECTIVE The aim of this study was to examine the results of microbiological cultures from local bone autografts used in posterior lumbar interbody fusion (PLIF) and to identify their association with postoperative spinal infection. METHODS The authors retrospectively evaluated cases involving 328 patients who had no previous spinal surgeries and underwent PLIF for degenerative diseases with a minimum 1-year follow-up. Local bone was obtained during laminectomy, and microbiological culture was performed immediately prior to bone grafting. The associations between culture results from local bone autografts and postoperative spinal infections were evaluated. RESULTS The contamination rate of local bone was 4.3% (14 of 328 cases). Coagulase-negative Staphylococcus (29%) was the most common contaminant isolated, followed by Streptococcus species and methicillin-sensitive Staphylococcus aureus. Of 14 patients with positive culture results, 5 (35.7%) had postoperative spinal infections and were treated with intravenous antibiotics for a minimum of 4 weeks. One of these 5 patients also underwent reoperation for debridement during this 4-week period. Regardless of the microbiological culture results, the infection rate after PLIF with local bone autograft was 2.4% (8 of 328 cases), with 5 (62.5%) of 8 patients showing positive results on autograft culture. CONCLUSIONS The incidence of contamination of local bone autograft during PLIF was considerable, and positive culture results were significantly associated with postoperative spinal infection. Special attention focused on the preparation of local bone for autograft and its microbiological culture will be helpful for the control of postoperative spinal infection.