Percutaneous Instrumentation Research Articles

Percutaneous pedicle screw for unstable spine fractures in polytraumatized patients: A report of two cases

Unstable spine fractures commonly occur in the setting of a polytraumatized patient. The aim of management is to balance the need for early operative stabilization and prevent additional trauma due to the surgery. Recent published literature has demonstrated the benefits of early stabilization of an unstable spine fracture particularly in patients with higher injury severity score (ISS). We report two cases of polytrauma with unstable spine fractures stabilized with a minimally invasive percutaneous pedicle screw instrumentation system as a form of damage control surgery. The patients had good recovery from the polytrauma injuries. These two cases illustrate the role of minimally invasive stabilization, its limitations and technical pitfalls in the management of unstable spine fractures in the polytrauma setting as a form of damage control surgery.

Facet Violation With the Placement of Percutaneous Pedicle Screws

Independent review and classification of therapeutic procedures performed on cadavers by surgeons blinded to purpose of study. The objective of this study is to determine the rate of facet violation with the placement of percutaneous pedicle screws. Improvements in percutaneous instrumentation and fluoroscopic imaging have led to a resurgence of percutaneous pedicle screw insertion in lumbar spine surgery in an attempt to minimize many of the complications associated with open techniques of pedicle screw placement. Rates of pedicle breech and neurologic injury resulting from percutaneous insertion are reportedly similar to those of open techniques. Postoperative pain because of impingement and instability is believed to result from violation of the facet capsule or facet joint. To the authors' knowledge, however, the rate of facet injury associated with the placement of percutaneous pedicle screws is unreported in the literature. Percutaneous pedicle screw placement was performed on 4 cadaveric specimens by 4 certified orthopedic surgeons who had clinical experience in the procedure and who were blinded to the study's purpose. The surgeons were instructed to place pedicle screws from L1-S1 using their preferred clinical techniques and a 5.5-mm screw system with which they were all familiar. All surgeons utilized 1 OEC C-arm for fluoroscopic imaging. After insertion, 2 independent spine surgeons each reviewed and classified the placement of all facet screws. A total of 48 screws were inserted and classified. The placement of 28 screws (58%) resulted in violation of facet articulation, with 8 of these screws being intra-articular. Interobserver reliability of the classification system was 100%. Percutaneous pedicle screw placement may result in a high rate of facet violation. Facet injury can be reliability classified and therefore, perhaps, easily prevented.

Gross hematuria caused by a congenital intrarenal arteriovenous malformation: a case report

IntroductionWe report the case of a woman who presented with gross hematuria and was treated with a percutaneous embolization.Case presentationA 48-year-old Caucasian woman presented with gross hematuria, left flank pain, and clot retention. The patient had no history of renal trauma, hypertension, urolithiasis, or recent medical intervention with percutaneous instrumentation. The patient did not report any bleeding disorder and was not taking any medication. Her systolic and diastolic blood pressure values were normal at presentation. The patient had anemia (8 mg/dL) and tachycardia (110 bpm). She underwent color and spectral Doppler sonography, multi-slice computed tomography, and angiography of the kidneys, which showed a renal arteriovenous malformation pole on top of the left kidney.ConclusionsThe feeding artery of the arteriovenous malformation was selectively embolized with a microcatheter introduced using a right transfemoral approach. By using this technique, we stopped the bleeding, preserved renal parenchymal function, and relieved the patient's symptoms. The hemodynamic effects associated with the abnormality were also corrected.

Common and unusual diseases involving the iliopsoas muscle compartment: spectrum of cross-sectional imaging findings

Although relatively uncommon, many different infectious, hemorrhagic and neoplastic disease processes may involve the iliac and psoas muscles and are increasingly diagnosed especially in referral hospitals. Furthermore, the iliopsoas compartment may become injured during trauma, percutaneous instrumentation, laparoscopic or open surgical procedures. State-of-the-art cross-sectional imaging including volumetric multidetector CT and multiplanar MRI acquisitions allows prompt detection, comprehensive visualization and confident characterization of most iliopsoas lesions, and the possibility to guide percutaneous biopsy and drainage. The pertinent regional anatomy is reviewed in correlation with disease pathways and imaging modalities. Neoplastic lesions, purulent and mycobacterial iliopsoas infections are discussed with examples. Imaging plays the key role in the differentiation of primary versus secondary abscesses due to intestinal, urinary and musculoskeletal infections, that determines medical therapy and surgical need. The iliopsoas compartment may become involved through direct extension by retroperitoneal, skeletal and pelvic tumors, and should be carefully scrutinized when reviewing oncologic imaging studies since it represents one of the preferred sites of skeletal muscle metastatization. Iliopsoas hemorrhages due to trauma, aortic aneurysms and anticoagulation are reviewed, with a special focus on determining whether the bleeding comes from aneurysmal rupture or from coagulopathy, a critical differentiation to decide about medical or surgical treatment. Postoperative complications involving the iliopsoas compartment are discussed with examples, including retroperitoneal bleeding, infections, urinary leaks and collections following various surgical or instrumentation procedures. Emphasis is placed on choosing the correct imaging modality and technique, particularly to detect active bleeding or urine leakage, and to reduce artifacts related to presence of metallic implants.

Percutaneous instrumentation of the cervical and cervico-thoracic spine using pedicle screws: preliminary clinical results and analysis of accuracy

The pedicle screw instrumentation represents the most rigid construct of the cervical and cervicothoracic spine and in spite of the risks to neurovascular structures clinical relevant complications do not occur frequently. The steep angles of the cervical pedicles result in a wide surgical exposure with extensive muscular trauma. The objective of this study was the evaluation of the accuracy of cervical pedicle screw insertion through a minimally invasive technique to reduce access-related muscular trauma. Therefore, percutaneous transpedicular instrumentation of the cervical and cervicothoracic spine was performed in 15 patients using fluoroscopy. All instrumentations from C2 to Th4 were inserted bilaterally through 2 to 3-cm skin and fascia incisions even in multilevel procedures and the rods were placed by blunt insertion through the incision. Thin-cut CT scan was used postoperatively to analyze pedicle violations. 76.4% of 72 screws were placed accurately. Most pedicle perforations were seen laterally towards the vertebral artery. Critical breaches >2mm or narrowing of the transversal foramen occurred in 12.5% of screws; however, no revision surgery for screw displacement was needed in the absence of clinical symptoms. No conversion from percutaneous to open surgery was necessary. It was concluded that percutaneous transpedicular instrumentation of the cervical spine is a surgically demanding technique and should be reserved for experienced spine surgeons. The indications are limited to instrumentation-only procedures or in combination with anterior treatment, but with the potential to minimize access-related morbidity.

Perkutane Techniken an der Brust- und Lendenwirbelsäule

Techniques of percutaneous spinal instrumentation have in the meantime become standard methods in many hospitals. While several indications have been established that are excellently suited to this technique, uncertainty prevails for other indications. This contribution intends to clarify the technical prerequisites for performing percutaneous instrumentation in the region of the thoracic and lumbar spine in addition to describing customary indications and various techniques of percutaneous instrumentation. This is combined with a critical assessment of what intrinsically cannot or cannot yet be achieved with a percutaneous approach to illustrate that the percutaneous procedure can by no means be considered a mere evolution of the previous classic open techniques.

A Prospective, Nonrandomized, Multicenter Evaluation of Extreme Lateral Interbody Fusion for the Treatment of Adult Degenerative Scoliosis

Prospective multicenter nonrandomized institutional review board-approved observational study of clinical and radiographic outcomes of the extreme lateral interbody fusion (XLIF) procedure in adult scoliosis. Perioperative measures from this longitudinal study were compiled to identify the short-term results and complications of the procedure. The surgical treatment of adult scoliosis presents a treatment challenge. Neural decompression with combined anterior/posterior instrumented fusion is often performed. These procedures have been reported to carry a high risk of complication, particularly in the elderly patient population. Over the past decade, less invasive surgical approaches to neural decompression and fusion have been popularized and have recently been applied in the treatment of degenerative scoliosis. To date, there has been little published data evaluating these treatment approaches. A total of 107 patients who underwent the XLIF procedure with or without supplemental posterior fusion for the treatment of degenerative scoliosis were prospectively studied. Intraoperative data collection included surgical procedural details, operative time, estimated blood loss, and surgical complications. Postoperative complications, length of hospital stay, and neurologic status were recorded. For this report, perioperative data (inclusive of outcomes through the 6-week postoperative clinic visit) were evaluated. In all, 107 patients (mean age, 68 years; range, 45-87) were treated with XLIF; 28% had at least 1 comorbidity. A mean of 4.4 levels (range, 1-9) were treated per patient. Supplemental pedicle screw fixation was used in 75.7% of patients, 5.6% had lateral fixation, and 18.7% had stand-alone XLIF. Mean operative time and blood loss were 178 minutes (58 minutes/level) and 50 to 100 mL. Mean hospital stay was 2.9 days (unstaged), 8.1 day (staged, 16.5%), 3.8 days overall. Five patients (4.7%) received a transfusion, 3 (2.8%) required intensive care unit admission, and 1 (0.9%) required rehabilitation services. Major complications occurred in 13 patients (12.1%): 2 (1.9%) medical, 12 (11.2%) surgical. Of procedures that involved only less invasive techniques (XLIF stand-alone or with percutaneous instrumentation), 9.0% had one or more major complications. In those with supplemental open posterior instrumentation, 20.7% had one or more major complication. Early reoperations (3) (all for deep wound infections) were associated with open posterior instrumentation procedures. The morbidity in adult scoliosis surgery is minimized with less invasive techniques. The rate of major complications in this study (12.1%) compares favorably to that reported from other studies of surgery for degenerative deformity.

Laparoscopic Circumcaval Ureteral Repair with Concomitant Laparoscopic-Guided Nephroscopic Calculi Extraction

Introduction: The pre-ureteral vena cava anomaly, erroneously termed the retrocaval or circumcaval ureter, is a relative rare condition of extrinsic ureteral obstruction. Despite being more common on the right kidney, when present on the left side, it is usually associated with sites inverses. The laparoscopic approach, with all of its know advantages, has good results when used to treat this congenital anomaly. The present surgical video shows a ureteral transposition with ureteropyolostomy, associated with a nephroscopic calyceal calculi extraction. Case Report: A 54 years old man, with discomfort in the right flank and abdominal echography showing a pelvicalyceal dilatation of this side and a calculus of 1.5 cm in a lower calyx. An intravenous pyelogram and abdominal computed tomography showed an S-shaped (Atkinson classification) pre-ureteral vena cava, and a mid-ureteral extrinsic stricture associated with it. There were no patient pre-operative comorbities and a percutaneous nephrolithotripsy was done 4 years prior on the right kidney. In the present video, a transperitoneal laparoscopic approach was conducted, with 4 trocars. In a stepwise fashion, the ureter suband supracaval was gently dissected, sectioned near the renal pelvis, transposed, and spatulated .A ureteropyelostomy was done over a double J stent, which was placed in an antegrade manner. After the posterior wall anastomosis completed, we performed a nephroscopy through the left hand trocar and the calyceal stone was removed by percutaneous stone instrumentation. Result: The surgery lasted 240 minutes, with minimum blood loss. The diet was resumed on the first postoperative day and he was discharged home on the third postoperative day. After 8 months of follow up, the patient remains asymptomatic and his excretory urography shows good drainage of the right kidney as well a diuretic renography reveals good response following 20 minutes after furosemide intravenous administration. Furthemore, the pelvicalyceal dilatation improved and there are no subsequent calculi. Conclusion: The laparoscopic approach to circumcaval ureteral anomalies is a feasible option, with concomitant endourologic procedures possible with good results. Int Braz J Urol. 2009; 35 (Video #2): 753_4 Available at: www.brazjurol.com.br/videos/november_december_2009/Curcio_753_754video.htm Accepted: November 8, 2009 Correspondence address: Dr. Lessandro Curcio Goncalves Section of Urology Ipanema General Hospital Rio de Janeiro, RJ, Brazil E-mail: lessandrocg@ig.com.br doi: 10.1590/S1677-553820090006000031

Use of isocentric fluoroscopy during transoral odontoidectomy

The intra-operative isocentric C-arm (Siremobil Iso-C 3D; Siemens Medical Solutions, Erlangen, Germany) allows for the acquisition and immediate interpretation of multiplanar three-dimensional images. The utility of isocentric fluoroscopy in surgery of the spine has been well described, in patients with percutaneous kyphoplasty, anterior cervical discectomy and fusion, fracture repair, as well as in percutaneous instrumentation at cervical, thoracic and lumbar levels. Two patients who underwent transoral odontoidectomy are presented in whom isocentric fluoroscopy was utilized to provide an intra-operative CT scan. Use of this technology allowed the surgeon to detect residual bone peri-operatively, thus allowing for a more extensive decompression and excellent clinical results. Intra-operative isocentric fluoroscopy in transoral odontoidectomy allows for peri-operative detection of residual bone fragments and intra-operative confirmation of complete decompression.

Percutaneous internal fixation in the management of lumbar spondylitis: Report of two cases

Surgically managed bacterial spondylitis is rare, and a variety of operative techniques are currently available, without any real consensus. The present study reports an original, less invasive surgical treatment for spondylitis, in two patients. An initial percutaneous posterior instrumentation fixation was followed by an anterior interbody graft performed through a retroperitoneal route. Postoperative bacterial typing was done; pain resolution was obtained in both patients. Control CT scan showed good restitution of the disk space height and a satisfactory reduction of the local kyphosis. Fusion was achieved at 6 months in both cases, with stable results at long-term follow-up. In patients presenting comorbid conditions, this technique gave interesting preliminary results, was less traumatic and shorter to perform, and finally entailed a limited operative risk.

Minimal-invasive perkutane Instrumentation bei Wirbelsäulenfrakturen

When operating unstable spine fractures by an open dorsal approach, detachment of paravertebral muscles results in bleeding and later functional disturbances. Long incisions over spinous processes cause pain and later cosmetic issues. With the sextant of Medtronic a system is at our disposal which permits a percutaneous approach with pedicle screws and longitudinal supports by a target device via six small incisions. From 15 November 2007 until 15 May 2008, 36 unstable spine fractures were treated by a minimally invasive technique; 14 men and 22 women were treated. The average age was 61 years (22-88 years). According to the Magerl classification there were mostly A3.3 fractures. The average incision-closure time was 42 min (14-96 min) with an average X-ray exposure time of 3.35 min (1.5-7 min). Blood loss was 10-20 ml and average hospital stay was 11 days. Pain judged according to a visual analog scale decreased from 6.1 to 1.4 points. Incorrect screw positions without clinical relevance were seen in 2% without necessity for revision. From 1 February 2007 until 15 November 2007, 40 patients (24 men, 16 women, average age 53 years) with unstable spine fractures were treated by the same surgeons by open dorsal instrumentation. The average operation time in this control group was 91 min and the average time at hospital 15.5 days. Percutaneous instrumentation with cannulation of pedicles with a guide wire under X-ray control permits a safe application while preserving soft tissues without relevant blood loss. Operating times can be drastically reduced compared with the open technique. The implants are more expensive but pay for themselves by shorter stays in the OR and hospital.

Pulmonary Embolism in the Critically Ill

Pulmonary embolism in the critically ill requires considerations beyond anticoagulant therapy. Measurements of chamber size by echocardiography and CT and of circulating biomarkers identify higher-risk patients with moderate accuracy and may aid determination of patient acuity. Preserving right ventricular function requires judicious use of volume administration, vasopressor, and perhaps vasodilator therapies. Obstructing thrombus can be treated with fibrinolytic drugs, percutaneous instrumentation, or surgically, but these treatments may not be equally effective or safe. Anticoagulant therapy in critically ill patients is likely best administered IV. Bleeding complications should be assiduously sought but do not necessitate anticoagulant discontinuation in every case. The antidotes protamine, desmopressin acetate, factor VIII inhibitory bypass activity, and recombinant factor VIIa may each have a place in controlling anticoagulant-related bleeding. The grave prognosis of heparin-induced thrombocytopenia warrants close surveillance, with rapid switching to lepirudin, argatroban, or fondaparinux necessary if it is suspected. Retrievable vena cava filters can be lifesaving, and at least one type may be safely removed after residence of nearly 1 year.

PERCUTANEOUS TRANSFORAMINAL LUMBAR INTERBODY FUSION FOR THE TREATMENT OF DEGENERATIVE LUMBAR INSTABILITY

Percutaneous spinal instrumentation techniques may be helpful to reduce approach-related morbidity inherent to conventional open surgery. This article reports technique, clinical outcomes, and fusion rates of percutaneous transforaminal lumbar interbody fixation (pTLIF). Results are compared with those of mini-open transforaminal lumbar interbody fixation (oTLIF) using a muscle splitting (Wiltse) approach. pTLIF was performed in 43 patients with single-level and 10 patients with bi- or multilevel lumbar discopathy or degenerative pseudolisthesis resulting in axial back pain and claudication, pseudoradicular, or radicular symptoms. Decompression, discectomy, and interbody cage insertion were performed through 18-mm tubular retractors followed by percutaneous pedicle screw-rod fixation. Clinical outcome was assessed by early postoperative pain scores (visual analog score) and standardized functional outcome questionnaires (American Academy of Orthopedic Surgeons lumbar spine and Roland-Morris low back pain score). Fusion rates were assessed by thin-slice computed tomographic scan at 16 months. Clinical outcome, time in the operating room, intraoperative blood loss, and postoperative access-site pain were compared with an institutional reference series of 67 oTLIF procedures. Excellent and good clinical results were obtained in 46 (87%) out of 53 patients at 16 months. The time spent in the operating room was equivalent and the blood loss reduced compared with oTLIF (P < 0.01). There was no morbidity related to instrumentation. Postoperative pain was significantly lower after pTLIF after the second postoperative day (P < 0.01). The overall clinical outcome was not different from oTLIF at 8 and 16 months. pTLIF allows for safe and efficient minimally invasive treatment of single and multilevel degenerative lumbar instability with good clinical results. Further prospective studies investigating long-term functional results are required to assess the definitive merits of percutaneous instrumentation of the lumbar spine.

POSTERIOR KEYHOLE CORPECTOMY WITH PERCUTANEOUS PEDICLE SCREW STABILIZATION IN THE SURGICAL MANAGEMENT OF LUMBAR BURST FRACTURES

The authors present a new method of minimally invasive surgical management of lumbar burst fractures through the posterior approach. The method includes minimally invasive corpectomy and interbody fusion, both of which are performed through a keyhole approach, and percutaneous pedicle screw fixation of the fracture. The technique of the posterior keyhole corpectomy presented in this report is a novel and original concept of the first author (AM). The percutaneous pedicle screw stabilization is performed with the use of a percutaneous instrumentation system (Sextant; Medtronic, Inc., Minneapolis, MN). The Sextant system has been dedicated and used in nontrauma degenerative cases; the novel aspect of this system is its application in spine fractures. Indications for the method include Denis classification subtype B or Magerl subtype A.3.1 burst fractures. Both subtypes represent fractures with failure and retropulsion of the upper part of the vertebral body. The clinical experience of this study includes four cases of burst fractures with significant retropulsion and occlusion of the spinal canal. Long-term results were assessed at a minimum follow-up period of 1 year (maximum, 3.5 yr). The follow-up assessments included: 1) the quality of decompression and reconstruction of the spinal canal (computed tomographic and magnetic resonance imaging scanning); 2) the stability of the operated segment (dynamic x-rays); 3) the quality of interbody fusion (computed tomographic scanning and dynamic x-rays); and 4) correction of the fracture kyphosis and its postoperative loss (measurements of Cobb angles for the assessment of sagittal plane deformity). The minimum armamentarium requirements for this method include a typical micro lumbar discectomy retractor set; a surgical microscope; two-plane intraoperative fluoroscopy; and a system for percutaneous pedicle screw stabilization (Sextant). "Posterior keyhole corpectomy" indicates corpectomy of the posterior upper half of the vertebral body or removal of the retropulsed bone fragment via two keyhole skin incisions on both sides of the spinous process (each skin incision measures 2 to 3 cm long). Exposure of the retropulsed fragment (the posterior upper part of the vertebral body) is achieved by medial or complete facetectomy along with complete or medial resection of the pedicle. This has to be performed bilaterally. Percutaneous stabilization requires four additional stab skin incisions. We observed no surgery-related complications (neurological, hardware, dural tears, or deep or superficial wound infections); there was perfect decompression and clearance of the spinal canal (confirmed by computed tomographic and magnetic resonance imaging scanning); and there was solid stability at the affected segments (confirmed by dynamic x-rays). Healed fusion was noted in all patients but one. The latter patient had no clinical symptoms of spinal instability. Kyphotic deformity was corrected and reversed into lordosis in three patients. Loss of deformity correction was noted in all patients; however, all patients retained lordotic alignment of the affected segment. The advantages of this method include sparing the posterior elements (lamina, spinous process, supraspinous and interspinous ligaments, and paravertebral muscles), safety of the decompression provided by the use of a surgical microscope, and perfect illumination of the operating field. The drawbacks of the method include limitation to certain types of burst fractures, the method is surgically demanding, and the method requires development of a special retractor system to eliminate the cumbersome alternate insertion and the reinsertions of the typical microdiscectomy retractor set.

Increased galectin-3 expression and intra-epithelial neutrophils in small airways in severe COPD

Galectins-1 and -3 regulate epithelial proliferation/apoptosis and neutrophil activation, and are implicated in lung cancer and asthma. The role of galectins in chronic obstructive pulmonary disease (COPD), characterised by epithelial changes and neutrophil infiltration, remains unknown. In the present study, galectin-1 and -3 expression was assessed by immunohistology in the bronchial epithelium of lung specimens from eight severe COPD patients and compared with nine nonsmokers and six smokers without COPD. Findings were related to epithelial proliferation (Ki-67), tissue inflammation and lung function. Epithelial galectin-3 immunostaining was increased only in the small airways of COPD patients when compared with nonsmokers and smokers. In contrast, galectin-1 was only significantly increased in the small airways of the group of smokers. Ki-67+ epithelial cells and neutrophils were increased in the small airways of COPD patients when compared with smokers. Furthermore, intra-epithelial neutrophils correlated in the small airways with Ki-67+ epithelial cells and with the forced expiratory volume in one second/forced vital capacity ratio. However, no correlation was observed with galectin expression. The present study supports the hypothesis that distal airways represent an important site for detecting changes in chronic obstructive pulmonary disease. In patients with severe disease, an increased galectin-3 expression and neutrophil accumulation in the small airway epithelium was demonstrated, correlating with epithelial proliferation and airway obstruction.

Minimally invasive microendoscopy-assisted transforaminal lumbar interbody fusion with instrumentation

The authors have developed a novel technique for percutaneous fusion in which standard microendoscopic discectomy is modified. Based on data obtained in their cadaveric studies they considered that this minimally invasive interbody fusion could be safely implemented clinically. The authors describe their initial experience with a microendoscopic transforaminal lumbar interbody fusion (METLIF) technique, with regard to safety in the placement of percutaneous instrumentation, perioperative morbidity, and early postoperative results. The METLIF procedure was performed unilaterally in 20 patients with single-level lumbar spondylolisthesis or pure mechanical back pain with endoscopic assistance, hemilaminectomy, unilateral facetectomy, and microdiscectomy. Two interbody grafts were placed via the lateral exposure of the disc space. Bilateral percutaneous pedicle screws were then inserted. Compared with patients who had undergone single-level posterior LIF at the same institutions, intraoperative blood loss, hospital length of stay (LOS), and postoperative narcotic agent use were significantly lower in the METLIF group. The mean LOS for the percutaneous fusion group was 3.4 days (5.1 days in those who underwent PLIF; p < 0.02). There have been no procedure-related complications in this series to date. The METLIF technique provided an option for percutaneous interbody fusion similar to that in open surgery while minimizing destruction to adjacent tissues. This technique was safe and exhibited a trend toward decreased intraoperative blood loss, postoperative pain, total narcotic use, and the risk of transfusion.

5:40 126. Minimally invasive transforaminal interbody fusion with percutaneous instrumentation: a prospective evaluation of two year outcomes in 31 patients

BACKGROUND CONTEXT: Minimally invasive interbody and pedicle screw instrumentation techniques have become exceedingly popular. Despite the interest and adoption of these techniques there are few published reports of patiet outcomes.

74. The placement of percutaneous spinal instrumentation using three-dimensional fluoroscopy

74. The placement of percutaneous spinal instrumentation using three-dimensional fluoroscopy

Minimally Invasive Percutaneous Posterior Lumbar Interbody Fusion

The wide exposure required for a standard posterior lumbar interbody fusion (PLIF) can cause unnecessary trauma to the lumbar musculoligamentous complex. By combining existing microendoscopic, percutaneous instrumentation and interbody technologies, a novel, minimally invasive, percutaneous PLIF technique was developed to minimize such iatrogenic tissue injury (MIP-PLIF). The MIP-PLIF technique was validated in three cadaveric torsos with six motion segments decompressed and fused. Preoperative variables measured from imaging included interpedicular distance, pedicular height and width, interspinous distance, lordosis, intervertebral height, Cobb angle, and foraminal height and volume. Using the METRx and MD spinal access systems (Medtronic Sofamor Danek, Memphis, TN), bilateral laminotomies were performed using a hybrid of microsurgical and microendoscopic techniques. The intervertebral disc spaces were then distracted and prepared with the Tangent (Medtronic Sofamor Danek) interbody instruments. Either a 10 or 12 by 22 mm interbody graft was then placed. Using the Sextant (Medtronic Sofamor Danek) system, percutaneous pedicle screw-rod fixation of the motion segment was completed. We then applied MIP-PLIF in three patients. For segments with preoperative intervertebral/foraminal height loss, MIP-PLIF was effective in restoring both heights in all cases. The amount of improvement (9.7 to 38% disc height increase; 7.7 to 29.9% foraminal height increase) varied directly with the size of the graft used and the original degree of disc and foraminal height loss. Segmental lordosis improved by 29% on average. Graft and screw placement was accurate in the cadavers, except for a single Grade 1 screw violation of one pedicle. The average operative time was 3.5 hours per level. In our three clinical cases, the MIP-PLIF procedure required a mean of 5.4 hours, estimated blood loss was 185 ml, and inpatient stay was 2.8 days, with no intravenous narcotic use after 2 days in any of the patients. All screw and graft placements were confirmed. A complete PLIF procedure can be safely and effectively performed using minimally invasive techniques, thereby potentially reducing the pain and morbidity associated with standard open surgery. Prospective, randomized outcome studies will be required to validate the efficacy of this exciting new surgical technique.

Methicillin-Resistant Staphylococcus Aureus Septic Arthritis of the Knee Secondary to Steroid/Anesthetic Injection

Methicillin-Resistant Staphylococcus Aureus Septic Arthritis of the Knee Secondary to Steroid/Anesthetic Injection