Nam-Su Chung

Subsidence of Polyetheretherketone Cage After Minimally Invasive Transforaminal Lumbar Interbody Fusion

Study Design: A retrospective case series. Objective: The aim of this study was to determine the rate of cage subsidence after minimally invasive transforaminal lumbar interbody fusion (MITLIF) conducted using a polyetheretherketone (PEEK) cage, and to identify associated risk factors. Summary of Background Data: Although various rates of cage subsidence after lumbar interbody fusion have been reported, few studies have addressed subsidence rate after MITLIF using PEEK cage. Methods: A total of 104 consecutive patients who had undergone MITLIF using a PEEK cage with a minimum follow-up of 2 years were included in this study. Cage subsidence was defined to have occurred when a cage was observed to sink into an adjacent vertebral body by ≥2 mm on the postoperative or serial follow-up lateral radiographs. The demographic variables considered to affect cage subsidence were the following: age, sex, body mass index, bone mineral density, diagnosis, number of fusion segment, and the quality/quantity of back muscle, and the cage-related variables considered were: level of fusion, intervertebral angle, cage size, cage position, and postoperative distraction of disc height. Logistic regression analysis was conducted to explore relations between these variables and cage subsidence. Results: For the 122 cages inserted, the rate of cage subsidence was 14.8% (18 cages), and cage subsidence occurred within 7.2±8.5 (1–25) months of surgery. The odds ratios for factors found to significantly increase the risk of cage subsidence were; 1.950 (95% confidence interval, 1.002–4.224) for L5-S1 level, and 1.018 (95% confidence interval, 1.000–1.066) for anterior cage position. Conclusions: The rate of PEEK cage subsidence after MITLIF was relatively low. End-plate manipulation and cage insertion during MITLIF were not influenced by a small operation window.

Change in sagittal profiles after decompressive laminectomy in patients with lumbar spinal canal stenosis: a 2-year preliminary report.

Study Design. Retrospective radiological study. Objective. We aimed to determine whether the sagittal profiles of patients with lumbar spinal canal stenosis (LCS) change after decompressive laminectomy. Summary of Background Data. Decompressive laminectomy is the standard technique in the surgical treatment for LCS. Numerous studies have reported favorable clinical outcomes. However, few studies have quantitatively evaluated the radiological outcome of the procedure, including the global balance of the spine and associated pelvic posture. Methods. This study involved 40 consecutive patients with LCS treated with decompressive laminectomy and a control cohort of 40 age- and sex-matched patients with LCS who were treated conservatively. The radiological parameters of the 2 groups including (1) global sagittal balance (C7 plumb line [C7PL], C7/sacrofemoral distance ratio, and spinosacral angle), (2) spinopelvic morphology (pelvic incidence, sacral slope, and pelvic tilt), and (3) spinal parameters (lumbar lordosis and thoracic kyphosis) were measured and compared at baseline, 1-year, and 2-year follow-ups. Results. The demographics and baseline radiological parameters were similar between the 2 groups. The mean C7PL of the laminectomy group was 3.9 ± 2.5 cm at baseline, which decreased significantly to 2.0 ± 1.9 cm at the 1-year follow-up (P = 0.006) and was maintained at this level at the 2-year follow-up (2.3 ± 2.1 cm) (P = 0.013). The mean lumbar lordosis of the laminectomy group was 31.4°± 15.1° at baseline, which increased significantly to 35.6°± 11.7° at the 1-year follow-up (P = 0.021) and was maintained at this level at the 2-year follow-up (35.1°± 14.8°) (P = 0.044). Conclusion. In this study, decompressive laminectomy caused posterior migration of the C7PL and increased the lumbar lordosis. Level of Evidence: 3

Is It Beneficial to Remove the Pedicle Screw Instrument After Successful Posterior Fusion of Thoracolumbar Burst Fractures

Study Design. Case-control study. Objective. To investigate the clinical and radiological outcomes of pedicle screw removal after successful fusion of thoracolumbar burst fractures. Summary of Background Data. Implant removal is a common procedure in orthopedic surgery, although the benefits of and indications for removal remain controversial. Previous studies on pedicle screw removal have reported conflicting outcomes, because the study subjects and surgical goals were heterogeneous in nature. Methods. We studied 45 consecutive patients who underwent implant removal and a control cohort of 45 age- and sex-matched patients who retained their spinal implants after successful posterior fusion of thoracolumbar burst fractures using pedicle screw instrument. In most cases, long-segment instrumentation with short-segment posterior fusion was performed. The mean elapsed period prior to implant removal after index fracture surgery was 18.3 ± 17.6 months. A visual analogue scale for back pain was applied, the Oswestry disability index calculated, and radiological parameters derived at the time of implant removal and 1 and 2 years postoperatively obtained. These data were compared with those of the control group evaluated at the same times after index fracture surgery. Results. Patient demographics, mechanisms of injury, fracture morphologies, and the outcomes of index fracture surgery were similar between the 2 groups. The mean visual analogue scale and Oswestry disability index scores were better at both the 1- and 2-year follow-ups in the implant removal group than in the control group (all P values = 0.000). The segmental motion angle of the implant removal group was 1.6° ± 1.5° at the time of implant removal, and increased significantly to 5.8° ± 3.9° at 1-year follow-up (P = 0.000), and was maintained at this level at the 2-year follow-up (5.9° ± 4.1°) (P = 0.000). Conclusion. In patients treated successfully for thoracolumbar burst fractures, pedicle screw removal is beneficial because it alleviates pain and disability. Restoration of the segmental motion angle after implant removal may contribute to the clinical improvement. Level of Evidence: 3

Trabecular microstructure of the human lunate in Kienböck’s disease

The trabecular microstructure of normal lunates and lunates with Kienböck’s disease was investigated using micro-computed tomography (micro-CT). Five lunates with advanced Kienböck’s disease were obtained during lunate excision and scaphocapitate fusion, and five control lunates were from embalmed cadavers. Microstructural morphometric parameters were measured using micro-CT images. Trabeculations of lunates with Kienböck’s disease were 2.67 times denser and 1.84 times thicker than those of normal lunates. Furthermore, bone surface areas were 1.43 times greater and bone volume 2.67 times greater, and structural model indices were significantly lower in lunates with Kienböck’s disease. The study estimated that high mechanical stress would be applied to lunates with Kienböck’s disease, and suggests that new bone formation and collapse may play important roles in the microstructural changes in the lunate with advanced Kienböck’s disease.

Assessment of Hip Abductor Power in Patients With Foot Drop: A Simple and Useful Test to Differentiate Lumbar Radiculopathy and Peroneal Neuropathy

Study Design. Prospective study on a diagnostic test. Objective. To determine the usefulness of hip abductor power assessment in the differential diagnosis of foot drop due to lumbar radiculopathy and peroneal neuropathy. Summary of Background Data. Foot drop arises from various neuromuscular conditions. Differential diagnosis obvious in the typical case, however, is often inconclusive. There are few reports regarding the validity of hip abductor power in the differential diagnosis of foot drop. Methods. Sixty-one consecutive patients who presented with tibialis anterior weakness Medical Research Council grade of less than 3 were included and underwent neurological examination including the assessment of hip abductor power. Patient demographics, mechanism and pattern of foot drop, neurological findings, and the diagnoses were recorded. Final diagnoses were established on the basis of clinical information, imaging studies, and electrophysiological study in limited cases. Validity and reliability of the hip abductor power assessment in the differential diagnosis of foot drop due to lumbar radiculopathy and peroneal neuropathy were evaluated. Results. There were 44 men and 17 women, with a mean age of 46.8 years (19–77 yr). The final diagnosis was peroneal neuropathy in 28 patients, lumbosacral plexopathy in 9 patients, lumbar radiculopathy in 21 patients, and sciatic nerve disorder in 3 patients. Concomitant hip abductor weakness was found in 85.7% of lumbar radiculopathy and 3.6% of peroneal neuropathy. The sensitivity and specificity of hip abductor power in the differential diagnosis of foot drop due to the lumbar radiculopathy and peroneal neuropathy were 85.7% and 96.4%, respectively. The positive and negative predictive values were 94.7% and 90%, respectively. Conclusion. Assessment of hip abductor strength is a simple and useful method in the differential diagnosis of foot drop due to lumbar radiculopathy and peroneal neuropathy.

Intraneural ganglion in the digital nerve of the thumb: A case report

Intraneural ganglion cysts of the peripheral nerve in the upper extremity are uncommon and usually originate within the epineurium of the peripheral nerve. The current report discusses a 57-year-old woman with a neuropathic nodular mass on the thenar area of the left hand. Magnetic resonance images showed a lobulated, homogeneous mass of high signal intensity on T2-weighted images and low signal intensity with peripheral enhancement on T1-weighted images. Excisional biopsy and histopathologic examination confirmed an intraneural ganglion cyst of the digital nerve of the thumb. A successful result was obtained by surgical treatment, and there was no recurrence of abnormal sensation and paraesthesia during the 3-year follow-up period.

Degenerative retrolisthesis: Is it a compensatory mechanism for sagittal imbalance?

We investigated the spinopelvic morphology and global sagittal balance of patients with a degenerative retrolisthesis or anterolisthesis. A total of 269 consecutive patients with a degenerative spondylolisthesis were included in this study. There were 95 men and 174 women with a mean age of 64.3 years (sd 10.5; 40 to 88). A total of 106 patients had a pure retrolisthesis (R group), 130 had a pure anterolisthesis (A group), and 33 had both (R+A group). A backward slip was found in the upper lumbar levels (mostly L2 or L3) with an almost equal gender distribution in both the R and R+A groups. The pelvic incidence and sacral slope of the R group were significantly lower than those of the A (both p < 0.001) and R+A groups (both p < 0.001). The lumbar lordosis of the R+A group was significantly greater than that of the R (p = 0.025) and A groups (p = 0.014). The C7 plumb line of the R group was located more posteriorly than that of the A group (p = 0.023), but was no different from than that of the R+A group (p = 0.422). The location of C7 plumb line did not differ between the three groups (p = 0.068). The spinosacral angle of the R group was significantly smaller than that of the A group (p < 0.001) and R+A group (p < 0.001). Our findings imply that there are two types of degenerative retrolisthesis: one occurs primarily as a result of degeneration in patients with low pelvic incidence, and the other occurs secondarily as a compensatory mechanism in patients with an anterolisthesis and high pelvic incidence.

Massive lumbar disc herniation with complete dural sac stenosis.

Background: Large lumbar disc herniation (LDH) has been reported to have a greater tendency to resolve in clinical and pathomorphological evolutions. However, various definitions of large LDH have been used without validation, and the clinical symptoms of large LDH have not been fully elucidated. We conducted a retrospective analysis to determine the clinical characteristics and treatment outcome of massive LDH with complete dural sac stenosis Materials and Methods: We retrospectively reviewed 33 cases of LDH with complete dural sac stenosis on magnetic resonance imaging. Complete dural sac stenosis was defined as no recognizable rootlet and cerebrospinal fluid signal on T2-weighed axial MR images. The clinical outcome parameters included back pain, leg pain, Oswestry disability index (ODI), and neurological dysfunction. The paired t-test and Wilcoxons signed rank test were used to compare serial changes in back pain, leg pain and neurological dysfunction. Results: Mean duration of followup was 66 months (range 24 - 108 months). There were 24 male and 9 female. The mean age was 37 years (range 20 - 53 years). At presentation, mean visual analogue scales for back pain and leg pain were 75.3 ± 19.1 (range 12 - 100) and 80.2 ± 14.6 (range 0 -100), respectively. Mean ODI was 67.1 ± 18.8 (range 26 - 88). Neurological dysfunction was found in 9 patients (27.3%), and the bowel/bladder dysfunction was found in 2 patients (3.1%). Conservative treatment was performed in 21 patients (63.6%) with satisfactory results. Seven patients underwent decompressive surgery, and 5 underwent posterolateral fusion. Conclusions: A massive LDH with complete dural sac stenosis was found to be associated with severe back and leg pain at presentation, however surgical treatment can be deferred unless significant neurological symptoms occur.

Reimplantation of an Extruded Humeral Segment into an Intact Periosteal Envelope in a Child

Traumatic bone extrusion followed by successful bone-segment reimplantation is uncommon1-4. When bone loss is minimal, open fractures may heal by stabilization alone, and small amounts of bone loss can generally be treated with an autogenous or allogenic bone graft. Large segmental bone defects may occur at the time of injury or after surgical debridement of devitalized bone, and may require large grafts, multiple grafts, vascularized bone grafts, or bone transport5-7. The benefits of reimplanting an extruded segment include maintenance of the original skeletal structure, avoidance of morbidity associated with autogenous bone harvesting, and avoidance of allograft bone procedures or prolonged bone transport procedures. Regardless of the sterilization method used, reimplantation of a devascularized bone segment after meticulous wound debridement and sound bone stabilization is associated with an elevated risk of infection. However, the literature lacks guidelines regarding the sterilization, timing of reimplantation, and stabilization of extruded bone segments1-4. We describe a case of early reimplantation of an extruded humeral segment in a child. The patient and her family were informed that data from this case would be submitted for publication, and they provided consent. A three-year-old girl fell from a third-floor balcony of an apartment and sustained an injury to the right arm and elbow. Her general condition was good, and she was alert and oriented. Other injuries included only a small scalp laceration and multiple superficial abrasions over the lower extremities. Physical examination revealed a 3-cm transverse laceration on the posterior aspect of the distal part of the right arm (just proximal to the olecranon) with moderate contamination, and gross motion indicating skeletal instability. A missing segment of humerus measuring 7.5 cm was retrieved by the parents from the scene approximately sixty minutes after the accident. The …

Global Sagittal Imbalance Due to Change in Pelvic Incidence After Traumatic Spinopelvic Dissociation

Objectives: To examine how spinopelvic morphology changes after traumatic spinopelvic dissociation and whether these changes affect the sagittal balance of the spine. Design: Retrospective analysis. Setting: Level I trauma center. Patients: Thirty-nine consecutive patients who were diagnosed with traumatic spinopelvic dissociation and had a minimum 2-year radiological follow-up were included. Intervention: Nineteen patients underwent spinopelvic pedicle screw fixation, 11 patients underwent percutaneous iliosacral screw fixation, and 9 patients were treated conservatively. Main Outcome Measurements: The main outcome measurements are as follows: (1) injury morphology (injury type and kyphotic angulation) at the initial and follow-up visits; (2) sagittal vertical axis (SVA) at the 2-year follow-up; (3) spinopelvic parameters [pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and thoracic kyphosis] at the 2-year follow-up; and (4) bodily pain and Oswestry Disability Index at the 2-year follow-up. Results: There were 21 men and 18 women, with a mean age of 28.3 years (15–62 years). At the 2-year follow-up, the mean SVA was 5.4 ± 4.1 cm and the mean PI was 76.9 ± 24.6 degrees. Factors related to SVA after traumatic spinopelvic dissociation were PI (r = 0.441, P = 0.017), pelvic tilt (r = 0.387, P = 0.038), and injury type of complete displacement (r = 0.372, P = 0.047). The bodily pain and Oswestry Disability Index was significantly poorer in patients with SVA modifier “+” than in patients with SVA modifier “0.” Conclusions: Lumbosacral kyphosis after traumatic spinopelvic dissociation increases PI, which can affect the sagittal balance of the spine and clinical outcome. Restoration of lumbosacral orientation is important for preventing sagittal imbalance. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.