Current evidence on where to end a fusion within the thoracolumbar junction most preferably - A systematic literature review.

Proximal junctional kyphosis (PJK) is one main complication in the surgical treatment of adult spinal deformities. Ending within the thoracolumbar junction (TLJ) should but cannot always be avoided to reduce the risk for PJK. With this systematic review we sought to define the most preferable vertebra within the TLJ to minimize the risk for PJK and establish recommendations based on our findings. We conducted a systematic literature review by scanning the MEDLINE database in accordance with the PRISMA criteria. All articles addressing primary long-distance dorsal thoracolumbar fusion of at least three segments to treat adult spinal deformities were included. 1385 articles were identified and three were included to this review. The first study showed significantly higher rates of PJK in patients where the construct was extended to T7 or higher when compared to an ending at T11 to L1. The second article stated that an expansion to the TLJ resulted in significantly less surgical revisions due to PJK reduction. On the other hand, the third article found that a fusion of the whole thoracic spine reduces the PJK incidence postoperatively. Even though the most favorable vertebra within the TLJ to avoid PJK best could not yet be determined, our study identifies several principles that represent the current state of evidence for surgical treatment of adult scoliosis. Proper preoperative decision making based on thorough analysis and interpretation of the patient's sagittal alignment parameters can improve the individual outcome critically.

Clinical outcome after lumbar spinal fusion surgery in degenerative spondylolisthesis: a 3-year follow-up.

INTRODUCTION: Lumbar spinal fusion surgery is a widely accepted surgical treatment in degenerative causes of lumbar spondylolisthesis. The benefit of reduction of anterior displacement and restoration of sagittal parameters is still controversially debated. Purpose of the underlying publication was to analyze the influence of radiographic sagittal parameters of the spine in aspects of changes in postoperative clinical outcome. MATERIALS AND METHODS: By prospective analysis, we included patients with low-grade degenerative lumbar spondylolisthesis (Meyerding grades I and II) with mono- or bisegmental fusion surgery with a minimum follow-up data of 3 years. For clinical outcome measures, COMI, ODI and EQ-5D were used. Spinopelvic parameters (sacral inclination, pelvic tilt, sacral slope and pelvic incidence, lumbar lordosis and lumbar index as well as anterior displacement and sagittal rotation) were measured on plain radiographs. RESULTS: We could observe a significant benefit in clinical outcome after lumbar fusion surgery in low-grade spondylolisthesis in our mid-term follow-up data including 32 patients. By surgical reduction, we could see significant restoration of anterior displacement and sagittal rotation. Interestingly, a significant correlation between restoration of both sagittal rotation and sacral inclination and clinical outcome score was observed in the 3-year follow-up. CONCLUSION: In low-grade spondylolisthesis, spinal fusion surgery is a well-established surgical procedure; however, the impact of sagittal parameters and reduction of anterior displacement remains controversial. Within our findings, restoration of sagittal parameters showed significant correlation to improvement in clinical outcome in our mid-term follow-up data.

The role of the transversal ligament on the atlantoaxial complex - Bending forces at C1/2 flexion limits in the elderly.

INTRODUCTION: Biomechanical functionality as well as trauma mechanisms of the atlantoaxial complex are still an issue of controversy. The transverse atlantal ligament is the strongest stabilizator. The present study aimed to analyze the bending forces of the transverse atlantal ligament and of the base of the odontoid in elderly specimens. METHODS: In this biomechanical study five cadaveric specimen with a mean age of 72 at death and bone mineral density measuring for 555.3 Hounsfield units on average were used. To analyze the strain of the transverse atlantal ligament and the dense base, strain gauges were used. A custom biomechanical setup was used to test each specimen at C1/2 flexion and the strain of the transverse atlantal ligament and the dens base (µm/m) were measured. FINDINGS: In four out of five, a rupture of the transverse atlantal ligament was observed, the mean force required for the ligament to fall was 175 N (min. 99.8 N; 249.2 N; SD 64.7) by a mean strain of 2102.9 µm/m (min. 1953.5 µm/m; max. 2272.3 µm/m; SD 189.7). In one specimen with the lowest Hounsfield units (155), the dens base fractured before the transverse atlantal ligament ruptured and no strain could be measured at the transversal ligament during movement afterwards. INTERPRETATION: The transverse atlantal ligament fails at an average of 175 N in the elderly, which is less than the value reported previously. In osteoporotic specimen the generated force to rupture the transverse atlantal ligament can fracture the dens itself.

Pathoanatomic Risk Factors for Instability and Adjacent Segment Disease in Lumbar Spine: How to Use Topping Off?

PURPOSE: The goal of this review is to identify criteria indicating implantation of hybrid system into lumbar spine and to evaluate general benefits of use. METHODS: A systematic review of literature was performed using current randomized clinical trials, reviews, and meta-analyses. Data sources included relevant literature of human studies identified through searches of Medline Library until May 2015. RESULTS: Predisposing factors for Adjacent Segment Disease (ASDi) are discussed in literature: laminar horizontalization, insufficiency of fascia thoracolumbalis, facet tropism, and facet sagittalization. Currently there is no evidence for topping off. There are only 12 studies and these have no consistent statements about use of a hybrid system for avoidance of ASDi. CONCLUSION: Hybrid instrumentation of lumbar spine, either with pedicle-based technique or additional spacer, might possibly prevent ASDi from developing in previously damaged segment adjacent to a fusion. Good clinical data proving effectiveness of this new implant technique is as yet unavailable. Thus, currently one must speak of an unevaluated procedure. Various radiological classifications can assist in making a reliable decision as to whether hybrid instrumentation is an appropriate choice of therapy. Pathoanatomical conditions of facet joints and laminae as well as preservation of sagittal balance must also be considered.

[The biomechanics of hyperextension injuries of the subaxial cervical spine]. / Biomechanik der Hyperextensionsverletzung der subaxialen Halswirbelsäule.

Hyperextension injuries of the subaxial cervical spine are potentially hazardous due to relevant destabilization. Depending on the clinical condition, neurologic or vascular damage may occur. Therefore an exact knowledge of the factors leading to destabilization is essential. In a biomechanical investigation, 10 fresh human cadaver cervical spine specimens were tested in a spine simulator. The tested segments were C4 to 7. In the first step, physiologic motion was investigated. Afterwards, the three steps of injury were dissection of the anterior longitudinal ligament, removal of the intervertebral disc/posterior longitudinal ligament, and dissection of the interspinous ligaments/ligamentum flavum. After each step, the mobility was determined. Regarding flexion and extension, an increase in motion of 8.36 % after the first step, 90.45 % after the second step, and 121.67 % after the last step was observed. Testing of lateral bending showed an increase of mobility of 7.88 %/27.48 %/33.23 %; axial rotation increased by 2.87 %/31.16 %/45.80 %. Isolated dissection of the anterior longitudinal ligament led to minor destabilization, whereas the intervertebral disc has to be seen as a major stabilizer of the cervical spine. Few finite-element studies showed comparable results. If a transfer to clinical use is undertaken, an isolated rupture of the anterior longitudinal ligament can be treated without surgical stabilization.

Inhalation anesthesia induced by isoflurane alters penicillin disposition in swine tissues.

Twelve healthy swine were dosed with penicillin G intramuscularly. Fluids and tissues samples were collected at the end of two periods of general anesthesia, performed 24 h apart. Tissue samples were collected by minimally invasive laparoscopy under general anesthesia at 8 and 28 h postdose. Four nonanesthetized, penicillin-treated pigs were euthanized at 8 h postdose, and a second set of four similarly treated control pigs were sacrificed 28 h postdose. Liver penicillin tissue concentrations from animals that underwent anesthesia and laparoscopic tissue collection had tissue concentrations that were higher than nonanesthetized pigs at both time points. Urine, plasma, kidney, skeletal, and cardiac muscle showed no differences between the two groups. Laparoscopic tissue collection under general anesthesia in swine induces physiological changes that cause alterations in tissue pharmacokinetics not seen in conscious animals.

Fracture risk of vertebral bodies after cryosurgery using a miniature cryoprobe: A biomechanical in-vitro analysis on human bones.

INTRODUCTION: Due to spinal instability and compressive neurologic deficits surgical management is sometimes necessary in patients with metastatic spinal lesions. However, in some cases open surgery is not possible and minimally invasive procedures, like cryoablation, are needed. The aim of the current study was to investigate whether a miniature cryoprobe provides adequate tissue cooling in vertebrae and to evaluate the direct impact of cryosurgery on vertebral body stability. MATERIALS AND METHODS: Twelve thoracic vertebral bodies were harvested from fresh cadavers. After documenting bone density cryoablation was performed in six vertebral bodies according to a standardized procedure. Afterwards temperature inside the vertebral body and maximum breaking force were measured in the control and experimental groups. RESULTS: Required temperature of -50° was reached in all areas. There was a significant correlation between maximum breaking force and measured bone density (p= 0.001). Mean breaking force within the experimental group was 5047 N (SD = 2955 N) compared to 4458 N (SD = 2554 N) in the control group. There were no observable differences in maximum breaking force between both groups. CONCLUSION: Miniature cryoprobe can deliver adequate tissue cooling to -50°C in vertebral bodies. The procedure does not seem to influence breaking force of the treated bones in-vitro. Therefore, using miniature probes cryosurgery may provide a valuable alternative to conventional surgical resection of neoplastic diseases as well as of benign locally aggressive bone tumors.

[3D Fluoroscopy-Navigated Magerl Fusion of the 1st and 2nd Cervical Vertebra]. / Navigierte Fusion des 1. und 2. Halswirbelkörpers nach Magerl.

Background: Treatment of type II fractures of the odontoid process is still controversial. Besides conservative treatment, there are surgical options, including anterior screw fixation, as first described by Böhler and Magerl, or procedures using a dorsal approach. Many authors prefer dorsal fusion of C1 and 2, due to the reliable, biomechanical stability. In this context, pedicle screw fixation, as described by Harms, and transarticular screw fixation of the atlantoaxial joints, as described by Magerl, have to be mentioned. With the use of intraoperative fluoroscopic navigation, the risk of neurovascular lesions caused by abortive drilling or malposition of screws has been significantly decreased. In 1993, Eysel and Roosen established a subclassification of type II fractures of the odontoid process and gave treatment recommendations for each of the three subtypes. While there was an outcome for type A and B fractures treated by anterior screw fixation, the authors recommended performing dorsal stabilisation at type C fractures. Indication: In accordance with the recommendations of Eysel and Roosen, an 82 year old man, suffering from a type II C fracture of the odontoid process, underwent navigated, transarticular screw fixation of C1 and C2. Method: Once the 3D-fluoroscopy scan had been performed, the correct drilling direction in the axial, coronary and sagittal views of C1 and 2 was found using the navigated drillguide. After K-wires had been inserted in this direction on both sides, a second 3D-scan was performed to recontrol placement of the K-wires. Cannulated screws were introduced and the rods were installed, bearing the atlas hook to fixate the posterior atlas. Conclusion: In summary, dorsal, transarticular fusion of C1 and C2 is a successful treatment option, rarely leading to complications and is accompanied by reduced radiation exposure to the operating team.

A novel classification of screw placement accuracy in the cervical spine.

BACKGROUND: Goal of this study is to present an easily reproducible and reliable measurement to evaluate accuracy of screw placement in cervical spine. METHODS: Accuracy of cervical screw position was assessed in 52 patients treated with 163 screws. Each patient receiving pedicle, transarticular C1/2, lateral mass, or laminar screws and postoperative CT scan was included. Placement position was categorized in 5 grades: Grade 1 is ideal with pedicle wall perforation < 1 mm, grade 2 < 2 mm, grade 3 < 3 mm, and grade 4 < 4 mm. Grade 5 > 4 mm and/or obstruction of transverse foramen by more than half a screw diameter. Intraclass correlation coefficient (ICC) values were assessed for inter- and intraobserver reliability. RESULTS: The mode of individual evaluations was calculated to assign a single value to each screw. This yielded 89 grade 1 (54.6%), 48 grade 2 (29.4%), 14 grade 3 (8.6%), 3 grade 4 (1.8%), and 9 grade 5 (5.5%) screws. Intraobserver reliability ICC was 0.966 and 0.959 for measurements. Interobserver reliability ICC was 0.938. CONCLUSION: This study introduces a reliable classification of cervical spine instrumentation with various screw types. This should enable the use of a uniform and reproducible, and thus comparable classification for screw position in cervical spine.

[Conservative treatment of nonspecific, chronic low back pain : Evidence of the efficacy - a systematic literature review]. / Konservative Therapie beim unspezifischen, chronischen Kreuzschmerz : Evidenz der Wirksamkeit - eine systematische Literaturanalyse.

OBJECTIVES: Non-specific chronic low back pain (NSCLBP): Which conservative therapy shows an evident effectiveness - A review of the current literature. MATERIALS AND METHODS: Our results are based on literature reviews of current randomised control studies, reviews and meta-analysis drawn from the Cochrane Library and Medline-Database between the years 2004 until 2015. German and English Studies were included. We focused on different conservative Treatments of NSCLBP, which are listed at, the NVL-Guidelines. Based on the given evidence we evaluated their effectiveness. RESULTS: As part of the review we identified 4657 Publications, 85 were included in this study. Therapeutic options such as bed rest, TENS, Massage, Spine Supports, Back Schools and Antidepressants showed no evident effectiveness. Injections, NSAR analgesic therapy, Thermotherapy and Opioid analgesic therapy indicated a short-time effectiveness. A long term success (> 6 weeks) however, can not be shown. Only the Movement therapy can, in the summation of the included studies, postulate an evident (Evidence Level I) long-term effect treating NSCLBP. Only a few therapy options indicate a significant evident effectiveness for treating NSCLBP conservatively. At short notice methods such as injection therapy, thermo-therapy and analgesic therapies with NSAR and/or opioids help coping the acute phase. In the long term only movement therapy seems to provide an evident effectiveness. In the case of therapy-refractory NSCLBP a multimodal therapy should be considered.

Influence of hip replacement on sagittal alignment of the lumbar spine: An EOS study.

INTRODUCTION: Changes in pelvic position can influence the sagittal alignment of the lumbar spine. The restoration of hip kinematics by hip replacement thus appears to offer the possibility of correcting sagittal alignment. This preliminary retrospective study used EOS imaging to investigate the influence of total hip arthroplasty on pelvic parameters in patients with normal preoperative pelvic parameters. METHODS: Twenty patients with hip osteoarthritis undergoing total hip arthroplasty (THA) between 2011 and 2012 received unilateral THA. To evaluate the preoperative and postoperative changes of the pelvic parameters, we analyzed EOS imaging of the patients to determine pelvic incidence, sacral slope, sacral tilt, pelvic tilt, anterior pelvic plane inclination and pelvic axial rotation. Additionally, anteversion and inclination of the acetabular cup position were determined. RESULTS: No statistically significant difference was found between the preoperative and postoperative measurements of pelvic parameters, although the change in pelvic tilt approached significance. Postoperatively, respective average values of 42.6° and 22.7° were measured for inclination and anteversion of the acetabular cup position. CONCLUSION: THA did not influence pelvic position and sagittal alignment in patients with normal preoperative pelvic parameters. A subsequent study will investigate whether corrections of pelvic parameters outside the norm in patients with OA are possible with THA.

Influence of spinopelvic parameters on non-operative treatment of lumbar spinal stenosis.

BACKGROUND: Non-operative treatment is widely accepted for early stages of lumbar spinal stenosis. In general, a trial of conservative treatment is recommended prior to surgery. OBJECTIVE: The influence of sagittal alignment on treatment outcomes remains unclear. METHODS: Twenty-five patients were included in this prospective study. All patients received repeated epidural injections and facet joint injections as well as physiotherapy during a one week hospitalization. Patient characteristics, VAS scores, COMI scores, ODI scores and SF-36 were assessed prior to and immediately after treatment as well as after six, twelve, and 26 weeks. Spinopelvic parameter measurements were performed. Outcome parameters were correlated to spinopelvic parameters. RESULTS: ODI and PCSS scores improved significantly up to three months follow-up. COMI score improved significantly over the entire follow-up. Back pain improvement at six weeks and three months follow-up correlated inversely with pelvic incidence. Sacral slope correlated significantly with ODI improvement immediately after therapy. Low lumbar lordosis also correlated significantly with ODI improvement at three months follow-up. CONCLUSIONS: Subjects with higher pelvic incidence reported significantly greater back pain improvements at three months follow-up. ODI improvements were higher for patients with high sacral slope immediately after treatment and for patients with a higher lumbar lordosis after three months. No influence of sagittal alignment was observed on leg pain or quality of life.

The accuracy of 3D fluoroscopy-navigated screw insertion in the upper and subaxial cervical spine.

PURPOSE: Due to better primary stability and repositioning options, pedicle screws are increasingly used during posterior stabilization of the cervical spine. However, the serious risks generally associated with the insertion of screws in the cervical spine remain. The purpose of this study is to examine the accuracy of pedicle screw insertion with the use of 3D fluoroscopy navigation systems, also accounting for various spine levels. METHODS: Data of 64 patients were collected during and after screw implantation (axial and subaxial) in the cervical spine. 207 screws were implanted from C1 to C7 and analyzed for placement accuracy according to postoperative CT scans and following the modified Gertzbein and Robbins classification. RESULTS: The accuracy of most of the inserted screws was assessed as grade 2 according to the modified Gertzbein and Robbins classification. 93.9% of the screws implanted at C1 or C2, and 78.51% of the screws implanted at levels C3-C7 showed placement accuracy grade 2 or better, indicating pedicle wall perforation of <2 mm. Overall, seven complications were observed. In three cases, the vertebral artery was affected, leading to one fatality. Surgical revision was necessary once because of Magerl screw misplacement and three times due to impaired wound healing. No radicular symptoms resulted from screw malposition. CONCLUSION: Axial and subaxial screws can be inserted with a high grade of accuracy using 3D fluoroscopy-based navigation systems. Nevertheless, while this useful innovation helps to minimize the risks of misplacement, the surgery is still a challenge, as arising complications remain severe.

Lumbar lordosis and sacral slope in lumbar spinal stenosis: standard values and measurement accuracy.

STUDY DESIGN: Radiological study. PURPOSE: To asses standard values, intra- and interobserver reliability and reproducibility of sacral slope (SS) and lumbar lordosis (LL) and the correlation of these parameters in patients with lumbar spinal stenosis (LSS). METHODS: Anteroposterior and lateral X-rays of the lumbar spine of 102 patients with LSS were included in this retrospective, radiologic study. Measurements of SS and LL were carried out by five examiners. Intraobserver correlation and correlation between LL and SS were calculated with Pearson's r linear correlation coefficient and intraclass correlation coefficients (ICC) were calculated for inter- and intraobserver reliability. In addition, patients were examined in subgroups with respect to previous surgery and the current therapy. RESULTS: Lumbar lordosis averaged 45.6° (range 2.5°-74.9°; SD 14.2°), intraobserver correlation was between Pearson r = 0.93 and 0.98. The measurement of SS averaged 35.3° (range 13.8°-66.9°; SD 9.6°), intraobserver correlation was between Pearson r = 0.89 and 0.96. Intraobserver reliability ranged from 0.966 to 0.992 ICC in LL measurements and 0.944-0.983 ICC in SS measurements. There was an interobserver reliability ICC of 0.944 in LL and 0.990 in SS. Correlation between LL and SS averaged r = 0.79. No statistically significant differences were observed between the analyzed subgroups. CONCLUSION: Manual measurement of LL and SS in patients with LSS on lateral radiographs is easily performed with excellent intra- and interobserver reliability. Correlation between LL and SS is very high. Differences between patients with and without previous decompression were not statistically significant.

Ventilation/perfusion SPECT/CT in patients with pulmonary emphysema. Evaluation of software-based analysing.

UNLABELLED: The purpose of this study was to evaluate the reproducibility of a new software based analysing system for ventilation/perfusion single-photon emission computed tomography/computed tomography (V/P SPECT/CT) in patients with pulmonary emphysema and to compare it to the visual interpretation. PATIENTS, MATERIAL AND METHODS: 19 patients (mean age: 68.1 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. Data were analysed by two independent observers in visual interpretation (VI) and by software based analysis system (SBAS). SBAS PMOD version 3.4 (Technologies Ltd, Zurich, Switzerland) was used to assess counts and volume per lung lobe/per lung and to calculate the count density per lung, lobe ratio of counts and ratio of count density. VI was performed using a visual scale to assess the mean counts per lung lobe. Interobserver variability and association for SBAS and VI were analysed using Spearman's rho correlation coefficient. RESULTS: Interobserver agreement correlated highly in perfusion (rho: 0.982, 0.957, 0.90, 0.979) and ventilation (rho: 0.972, 0.924, 0.941, 0.936) for count/count density per lobe and ratio of counts/count density in SBAS. Interobserver agreement correlated clearly for perfusion (rho: 0.655) and weakly for ventilation (rho: 0.458) in VI. CONCLUSIONS: SBAS provides more reproducible measures than VI for the relative tracer uptake in V/P SPECT/CTs in patients with pulmonary emphysema. However, SBAS has to be improved for routine clinical use.

Hypervascular cervical spine metastases: embolization by direct injection of Onyx-18.

PURPOSE: Spinal metastases are common in patients with cancer. Following lung and liver, spine is the most common site for cancers to metastasize. Many of them are hypervascularized. These cases are a particular challenge for the surgeon and represent a significant danger of massive blood loss during surgery. Hypervascularized metastases of the cervical spine also include the risk of postoperative bleeding with severe neurological impairment. We report a case of a 67-year-old women with breast cancer (BC) metastasis within the vertebral bodies of C3 and C4 with nearly complete bony destruction of the ventral column and intraspinal tumor masses compressing the spinal cord at level C3 and C4. The hypervascularized tumor was supplied by multiple minor vessels from both vertebral arteries, too small to be coiled individually. Due to an allergy to aspirin, intravascular stenting of the vertebral arteries was not an option. We decided to perform a preoperative direct injection of onyx-18 for embolization of the tumor. CONCLUSION: Presurgical direct injection of Onyx-18 for treating hypervascular spinal metastases of breast cancer seems to be an effective and safe technique and reduces intraoperative bleeding to a minimum.

Anterior spinal artery syndrome: reversible paraplegia after minimally invasive spine surgery.

Background Context. Percutaneous balloon kyphoplasty is an established minimally invasive technique to treat painful vertebral compression fractures, especially in the context of osteoporosis with a minor complication rate. Purpose. To describe the heparin anticoagulation treatment of paraplegia following balloon kyphoplasty. Study Design. We report the first case of an anterior spinal artery syndrome with a postoperative reversible paraplegia following a minimally invasive spine surgery (balloon kyphoplasty) without cement leakage. Methods. A 75-year-old female patient underwent balloon kyphoplasty for a fresh fracture of the first vertebra. Results. Postoperatively, the patient developed an acute anterior spinal artery syndrome with motor paraplegia of the lower extremities as well as loss of pain and temperature sensation with retained proprioception and vibratory sensation. Complete recovery occurred six hours after bolus therapy with 15.000 IU low-molecular heparin. Conclusion. Spine surgeons should consider vascular complications in patients with incomplete spinal cord syndromes after balloon kyphoplasty, not only after more invasive spine surgery. High-dose low-molecular heparin might help to reperfuse the Adamkiewicz artery.

A Holstein cow-calf model for the transfer of ciprofloxacin through milk after a long-term intravenous infusion.

This study is part of an ongoing effort to develop animal models that provide milk and sufficient infant (offspring) plasma samples to fully describe a drug's pharmacokinetics to quantitate the risk to the nursing infant. Ciprofloxacin was administered to six healthy Holstein cows as a constant rate intravenous infusion (flow rate was weight adjusted) to achieve a steady-state concentration of approximately 300 ng/mL for 7 days. Plasma and milk samples were collected from the cow at regular intervals over the course of the 7 days. The plasma and milk samples were analyzed for ciprofloxacin by high-performance liquid chromatography. The milk was fed to calves, and calf plasma samples were analyzed to study the lactational transfer of ciprofloxacin from dam to nursing neonate. Remarkably, concentrations of ciprofloxacin in milk were 45 times higher than plasma drug concentrations in the dam. Approximately 6% of the administered dose was transferred to the milk, resulting in an average oral dose of 0.5 mg/kg to the calves with every feeding. The drug did not accumulate in the calves, and plasma concentrations were between one-tenth and one-fifth the plasma concentrations of the dam.

Tissue/fluid correlation study for the depletion of sulfadimethoxine in bovine kidney, liver, plasma, urine, and oral fluid.

Sulfonamides are among the oldest, but still effective, antimicrobial veterinary medicines. In steers and dairy cows, the sulfonamides are effective in the treatment of respiratory disease and general infections. Sulfadimethoxine (SDM) has been approved by US Food and Drug Administration (FDA) for use in steers and dairy cows with a tolerance of 100 ng/g (ppb) in edible tissues and 10 ppb in milk. The detection of SDM residue above tolerance in the animal slaughtered for food process will result in the whole carcass being discarded. This report describes a comprehensive depletion study of SDM (and its main metabolite) in plasma, urine, oral fluid, kidney, and liver. In this study, nine steers were injected intravenously with the approved dose of SDM; the loading dose was 55 mg/kg, followed by 27.5 mg/kg dose at 24 h and again at 48 h. Fluids (blood, urine, and saliva) and tissue (liver and kidney) samples were collected at intervals after the last dose of SMD. The combination of laparoscopic serial sampling technique with the liquid chromatography/mass spectrometry method provided the data to establish the tissue/fluid correlation in the depletion of SMD. A strong correlation and linearity of the log-scale concentration over time in the depletion stage has been confirmed for kidney, liver, and plasma.