Lateral Entry Point Research Articles

Flexible Intramedullary Nail Placement in Pediatric Humerus Fractures.

Flexible intramedullary nailing is an effective method of stabilization in pediatric patients with a humeral shaft fracture when surgery is indicated1-3. Although these fractures are most often treated nonoperatively, operative indications include open fractures, bilateral injuries, compartment syndrome, pathologic fractures, neurovascular compromise, unacceptable alignment after attempted nonoperative treatment, and ipsilateral upper-extremity injuries4. The current literature on flexible intramedullary nailing of the pediatric humeral shaft lacks concise descriptions of available entry points, which directly affect the subsequent technique, and of pertinent pediatric-specific anatomy. Thus, the present article focuses on these entry points in the pediatric patient. Various entry points are available for the insertion of flexible nails into the humeral shaft. A surgeon must initially decide whether the patient and fracture characteristics are best suited for anterograde versus retrograde insertion. This choice typically depends on several fracture and patient-related characteristics. The passage of flexible intramedullary nails has been well described; thus, the present article will place special emphasis on the available proximal and distal entry points and pediatric-specific anatomy5-10. For diaphyseal fractures, we prefer dual distal lateral entry points with the nails advanced retrograde in a C-S configuration whenever possible, given the risks associated with proximal lateral entry (e.g., damage to the axillary nerve) or distal medial entry (e.g., damage to the ulnar nerve or nail prominence). A distal posterior supracondylar entry point is also possible but requires additional preoperative planning with regard to patient positioning, a more proximal entry point to avoid impingement of the olecranon on the nail in extension, and avoidance of the ulnar nerve. The substantial potential for remodeling in pediatric patients permits nonoperative treatment of humeral fractures if specific age-related criteria for angulation and displacement are met. Generally accepted tolerances for nonoperative angulation and displacement are as follows: for patients <5 years old, ≤70° angulation and up to 100% displacement; for patients 5 to 12 years old, 40° to 70° angulation; and for patients >12 years old, ≤40° angulation and 50% apposition4. The use of flexible nails is often preferred because of the healing potential of pediatric humeral shaft fractures, the ability of flexible nails to tolerate nonrigid fixation until osseous bridging occurs, the ability of the surgeon to avoid exposure of neurologic structures during surgery, and the benefit of avoiding physeal disruption. These factors make flexible nails a favorable option when compared with plate osteosynthesis or rigid intramedullary nailing. When indicated, the use of flexible intramedullary nails in pediatric humeral fractures has been associated with high rates of union, good functional outcomes, early range of motion, and an acceptably low rate of complications2. Be familiar with the technical details associated with all available entry points.Avoid damage to key neurologic structures around the proximal and distal humerus.Minimize the opportunity for symptomatic hardware.Optimize the biomechanics through flexible nail positioning at the fracture site. FIN = flexible intramedullary nailingEBL = estimated blood lossf/u = follow-upIM = intramedullaryMRI = magnetic resonance imagingOR = operating roomPT = physical therapyROM = range of motion.

Evaluating the safe zone for lumbar pedicle screws: are midline crossing screws indicative of pedicle breach?

BACKGROUND CONTEXTPedicle screw breach (PSB) is not uncommon following lumbar instrumentation, and in some instances, it may lead to vascular and/or neurologic complications. Previous literature suggested that screws crossing the vertebral midline on an anterior-posterior (AP) radiograph (or midsagittal on CT) are concerning for medial pedicle breach. OBJECTIVEOur primary aim was to map out the safe zones (SZ) of bilateral pedicle instrumentation and their relationship at each lumbar vertebral level. Our secondary aim was to evaluate the presence of SZs’ intersection at each lumbar level, denoting safe midline pedicle screw crossing not otherwise associated with medial pedicle breach. STUDY DESIGN/SETTINGRetrospective Anatomical Study. PATIENT SAMPLEAdult patients in the from “The Cancer Imaging Archive” (TCIA) database who have not had thoraco-lumbo-sacral fusion. OUTCOME MEASURESPhysiologic measures obtained through 3D analysis of CT images and virtual pedicle screws. METHODCT scans of 51 patients were randomly selected from “The Cancer Imaging Archive” (TCIA) online database for analysis. The Sectra 3D Spine software was used to create 3D renderings, place virtual screws, and make measurements. At each lumbar vertebra, the right and left pedicle corridors were mapped. At each pedicle, two screw positions were templated, the “medial limit screw” (MLS) and the “lateral limit screw” (LLS). Each limit screw was the most extreme position that the screw could exist in without causing a medial or lateral breach. The safe zone was defined as the zone between MLS and LLS. Measurements were taken for each level (between L1 and L5) and side (Left, Right). RESULTSA total of 253 lumbar vertebrae from 51 patients (mean age 53.1, 56.9% male) were included. Two vertebrae from two patients were removed for poor image quality. Out of the 506 screw positions analyzed in our study, 97.4% had overlapping SZ and crossed the midplane without medial pedicle breach. The significant factors (p<.01) for safe midplane-crossing screws included: the screw length (L1–L5); the laterality of the screw entry point (L1–L4); and the pedicle diameter (L2 and L5). CONCLUSIONSA midline crossing pedicle screw on a lumbar AP radiograph is not necessarily indicative of a medial pedicle screw breach. Anatomical (ie, larger pedicle diameter) and technical (ie, longer screws, and lateral entry points) factors allow for safety zone intersections and indicate safe midline crossing by pedicle screws.

The Kumar Technique: A Novel and Effective Approach to Transforaminal Epidural Steroid Injections.

Background Transforaminal epidural steroid injections (TFESIs) are widely used as a minimally invasive treatment for lumbar radicular pain. This study presents an alternative approach for lumbar TFESI, the Kumar Technique, which utilizes a more lateral and inferior needle starting point to better align the trajectory of the needle with the neural foramen. We hypothesize the Kumar Technique will result in safer and more effective outcomes than the traditional approach to TFESI. This article was previously presented as a poster at the 2023 University of Florida College of Medicine Celebration of Research on February 27-28, 2023, and as an abstract and poster at the 2023 University of Florida Department of Anesthesiology Celebration of Research on March 29, 2023. Methods The charts for 1,424 patients who received lumbar TFESIs were retrospectively reviewed, and patients were stratified into groups receiving either the traditional approach or the Kumar Technique. Outcomes measures included numerical pain scores, measures of functional status and activity limitations, duration of pain relief, and procedural complications. Results Compared to the group undergoing the traditional approach, patients receiving the Kumar Technique reported a significantly greater decreasein average pain (-2.3 (95% CI: -3.0 to -1.6) vs -1.1 (95% CI: -1.4 to -0.7)) and maximum pain (-2.4 (95% CI: -3.2 to -1.6) vs -1.3 (95% CI: -1.8 to -0.9)). Patients receiving the Kumar Technique had a significantly greater likelihood of reporting any pain relief (OR: 2.10, 95% CI:1.59 to 2.79) compared to those undergoing the traditional approach. In addition, a greater percentage of patients receiving the Kumar Technique experienced at least one month of pain relief compared to the traditional approach (54% vs 40%; z = 3.85, p < 0.001). The occurrence of complications did not significantly vary between the modified (4.1%) and the traditional (3.0%) approaches. Conclusions The Kumar Technique is a modified TFESI approach that allows for improved access to the nerve roots through a more lateral and inferior needle entry point. The analysis supports the benefits of the Kumar Technique with patients experiencing a greater reduction in pain and longer durations of pain relief without increasing the risk of complications.

An evolutionary perspective to intramedullary nail fit - comparing present-day data with a historical specimen collection.

Manufacturers aim to design implants fitting for the broadest possible population segment. Due to the scarcity of available morphological data of intact long bones, anatomical collections of historical bone specimens may represent valuable additional sources. Previous work on femoral morphology measurements suggests that historical specimens are widely consistent with data from present-day populations. This study aimed to investigate whether this also applies to the anatomical fitting of a clinically used femoral nail. Nail fit was computer-graphically quantified through virtual implantation into CT-based 3D models of 52 femora, comprising a subset representative of the present-day Caucasian population (n = 31), a subset from a historical medieval European bone collection (n = 20), and additionally, a dataset from a natural ice mummy from the Neolithic period. Nail fit was assessed by nail protrusion (area and distance) to the inner cortex surface and the distal nail tip's position in the medullary canal. Assessed measurements and parameters of the present-day Caucasian subset were mostly consistent with those of the medieval European subset. After adjusting for multiple testing, only the distance from lateral nail entry point to shaft axis remained significantly (p = 0.03) different when comparing our modern and medieval subsets. Subsequent bivariate (Spearman) correlation analyses for both subsets (modern and medieval) combined showed that of the three variables representing basic demographic parameters, individual age, biological sex, and femur length, most statistically significant associations to the examined nail fit measurements were found for age (six measurements at a level of p < 0.05), however, with a relatively weak monotonic correlation (rho values ranging between ±0.31 and ±0.37). The measurements for the Iceman's femur lie within the range of the modern and historical subgroups, but in some cases, differ by more than one standard deviation from the mean. Our results confirm previous findings, suggesting that more recent historical bone specimen collections may indeed be a convenient and easily accessible source of new 3D morphological data and complement existing data to be used for the development of femoral nails.

Surgical strategy of the treatment of atypical femoral fractures.

The atypical femoral fracture (AFF) has been attracting significant attention because of its increasing incidence; additionally, its treatment is challenging from biological and mechanical aspects. Although surgery is often required to manage complete AFFs, clear guidelines for the surgical treatment of AFFs are currently sparse. We reviewed and described the surgical treatment of AFFs and the surveillance of the contralateral femur. For complete AFFs, cephalomedullary intramedullary nailing spanning the entire length of the femur can be used. Various surgical techniques to overcome the femoral bowing common in AFFs include a lateral entry point, external rotation of the nail, and the use of a nail with a small radius of curvature, or a contralateral nail. In the case of a narrow medullary canal, severe femoral bowing, or pre-existing implants, plate fixation may be considered as an alternative. For incomplete AFFs, prophylactic fixation depends on several risk factors, such as a subtrochanteric location, presence of a radiolucent line, functional pain, and condition of the contralateral femur; the same surgical principles as those in complete AFFs can be applied. Finally, once AFF is diagnosed, clinicians should recognize the increased risk of contralateral AFFs, and close surveillance of the contralateral femur is recommended.

A computed tomography (CT) based morphometric study of superior pubic ramus anatomy among Arabs to determine safe intramedullary pubic rami screw insertion.

To assess the morphometric variables of the superior pubic ramus in an Arab/ Middle Eastern population to establish a safe pubic screw fixation technique. Cross-sectional retrospective analysis of computed tomography (CT) pelvic images. Morphometric data were extracted including; on pubic ramus length, insertion angles, potential danger zones and ramus diameters. The correlation between pubic rami diameter and patient demographics was also analyzed. A total of 231 participants were included (45% female). The mean pubic ramus length was 104mm in females and 127mm in males. The narrowest canal diameters at the para-symphyseal area were; 7.35mm (males) and 4.75mm (females). The mediolateral insertion angle was 49.4° in females and 41.8° in males. The cephalic-caudal angle was 49.9° in males and 42.1° in females. The mean distance from the lateral ilium entry point to the joint articular surface was 23.5mm in males and 19.9mm in females. The symphysis pubis to tubercle exit point was higher in females than males (24.2mm vs 16.6mm, respectively). There was a significant positive correlation between age and pubic ramus diameters in all age groups. The results from this study suggest that percutaneous pubic rami screw fixation using the standard 6.5 or 7.3mm cannulated screw system may potentially be unsafe in female Arab patients. This subset of patients may require alternative non-cannulated screws (3.5-4.5mm) or plate options. Further, female patients may have a higher risk of acetabular joint penetration, while males have a potentially higher risk of pudendal nerve injury.

New classification of S1 pedicle morphometry impacting pedicle screw insertion technique

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; The conventional entry point for the S1 pedicle screw insertion has been described as ‘at the base of and lateral to the superior S1 superior facet’. However, many orthopaedic surgeons complain that this technique is extremely demanding and is faced with many challenges in execution. Therefore, alternative entry points and modifications of existing techniques are explored for a greater convenience.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods&lt;/strong&gt;: We conducted a survey amongst 136 spine surgeons on the technical difficulties faced during insertion of the S1 pedicle screw. We also classified the S1 pedicles based by measuring their geometric parameters on 100 random computed tomography (CT) images.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;: The S1 pedicle entry technique was considered to be the most difficult and challenging by the orthopaedic surgeons in our survey due to an inadequate medial angulation due to paraspinal muscle mass tension and an overhanging iliac crest. This could be explained by the hourglass shaped pedicle (type 3) with a desired medial angle more 50 degrees (type III) observed as the most common S1 pedicle in the study population. To overcome this limitation, most of them preferred a tri-corticate approach.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: A more lateral entry point and a longer screw might be considered as solutions for a better and safer S1 pedicle entry. Also, the use of pre-operative CT can be considered to visualize the type of S1 pedicle and hence, decide on the most appropriate technique of screw insertion.&lt;/p&gt;&lt;p&gt;&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;

Defining the safe corridor for transcondylar screw placement in the feline humeral condyle.

The aim of this study was to develop guidelines for the optimal location of drill entry and exit points for insertion of a transcondylar screw across the feline humeral condyle. Multiplanar reconstruction of feline elbow CT scans performed between 2016 and 2021 at one referral institution were reviewed. The optimum medial and lateral epicondylar entry and exit points for transcondylar screw placement were determined. These values were normalised to the humeral condylar diameter (HCD) for each elbow to determine the transcondylar screw placement guidelines. These guidelines were applied to each elbow and tolerance angles were determined in the transverse and frontal plane CT images to determine the safe corridor for screw placement. Twenty elbows from 12 cats were evaluated in this study. The guidelines for transcondylar screw placement were as follows: the medial entry/exit point was 0.38 × HCD cranial and 0.16 × HCD distal to the medial epicondyle, and the lateral entry/exit point was 0.3 × HCD cranial and 0.16 × HCD distal to the lateral epicondyle. Tolerance angles were statistically significantly (P <0.05) larger in both frontal (34.5% larger) and transverse (21.1% larger) planes when drilled from a lateral to medial direction compared with drilling from a medial to lateral direction. The guidelines determined from this study may aid clinicians in the placement of humeral transcondylar screws in cats. Where possible, drilling from a lateral to medial direction is recommended owing to the higher tolerance angles reducing the likelihood of articular surface damage. Further studies are warranted to determine whether these guidelines are clinically useful and result in the safe insertion of a transcondylar screw in the clinical setting.

Does the Entry Point of Proximal Femoral Nail Antirotation Affect the Malalignment of Intertrochanteric Fracture? A Cadaveric Study

Purpose: Proximal femoral nailing (PFN) is a reliable and common procedure for treating intertrochanteric fractures. The optimal entry point is considered a critical step in avoiding malreduction. This study investigated the effects of various entry points on fracture displacement and force reduction. Methods: Twenty-four cadaveric femurs were randomly categorized into three groups: the greater trochanter (GT) tip, medial to the GT tip, and lateral to the GT tip. Each intact femur was provisionally stabilized using a ring external fixator. The entry point was identified and reamed to accommodate the nail insertion. After osteotomy was performed to simulate an A1-type fracture, the PFN was inserted. Digital calipers were used to measure horizontal fracture displacements. The force required to reduce displaced fractures to the anatomical position was measured using a digital force gauge. Fluoroscopic images were recorded to assess changes in the neck-shaft angle. Results: The lateral entry group showed significantly displaced fractures in the coronal plane, whereas the medial and tip entry groups were insignificant. Displacement in the sagittal plane was not significantly different between the groups. The lateral entry group showed significantly irreducible displaced fractures compared with the other groups. After nail insertion, the changes in the neck-shaft angle were 0.77° varus, 3.66° valgus, and 3.16° varus in the tip, medial, and lateral entry groups, respectively. The degree of neck-shaft angle change demonstrated significant differences between the groups. Conclusions: The lateral entry point of PFNA tends to displace reduced fractures, resulting in malalignment and irreducibility. Lateral entry points should be avoided to prevent surgery-related complications.

Influence of the femoral entry point for intramedullary alignment in total knee arthroplasty: A computer-aided design approach.

Objectives The aim of this study was to simulate different entry points and investigate potential angulation errors of the intramedullary device and resulting changes in the distal femoral cut using a computer-aided design (CAD) approach.Materials and methods We used a CAD approach to simulate various distal femoral entry points for intramedullary instrumentation. Simulations were performed on (i) a commercially available three-dimensional (3D) CAD model of a human femur (DigitalFemur) and (ii) a digital 3D model of an analogue large femur model produced using a coordinate measuring machine (FaroFemur). Divergent insertion points medial, lateral, anterior and posterior to the ideal position were simulated. Angulation deviations of the resulting positions of the intramedullary rod were measured and changes in the anatomical-mechanical axis angle were calculated. Differences between the two simulation models were quantified.Results The ideal entry point in the FaroFemur was 9.9 mm anterior and 4.3 mm medial to the apex of the intercondylar notch, and 9.2 mm anterior and 3.6 mm medial in the DigitalFemur. A medial entry point increased the angle between the anatomical femoral axis and the alignment rod in the FaroFemur and DigitalFemur (with 5 mm displacement 2.510° and 2.363°, respectively; with 10 mm displacement 3.239° and 3.283°, respectively). In contrast, a lateral entry point decreased the angle between the anatomical femoral axis and the alignment rod (with 5 mm displacement 2.267° and 2.262°, respectively; with 10 mm displacement 3.158° and 3.731°, respectively). An anterior entry point changed the angle between the anatomical femoral axis and the alignment rod towards extension (1.802° in the FaroFemur; 2.142° in the DigitalFemur), while a posterior entry point generated a deviation toward flexion (2.045° in the FaroFemur; 2.055° in the DigitalFemur). The mean difference between the two models was 0.108±0.121° with the highest difference for anterior displacement.Conclusion Minor deviations of the entry point for intramedullary instrumentation during total knee arthroplasty can result in malalignment of several degrees.

RCC (reinforced criss-cross construct): an easy and effective multi-rod thoraco-lumbar posterior reconstruction technique.

Surgical technical note and literature review. To describe a technique that uses 4 rod constructs in cases of complex thoracolumbar spinal deformity correction or revision surgeries based on the hybrid use of two different types of purchase points by a staggered pedicle screw fixation. It utilizes two rods on either side of the spine using a lateral and medial entry point of pedicle screws in the vertebral body. Pedicle screws using extra-pedicular technique are more converging screws and are inserted alternately in the vertebral body and connected by rods. The left-out alternate vertebral bodies are fixed by a relatively straighter pedicle entry screw and connected to each other by a separate rod. So, two trajectories are independently used for a four-rod construct. This reconstruction has been named RCC (reinforced criss-cross construct). The screws in the index case were placed by free hand method, but we have increasingly utilized navigation guidance for placement of screws in recent times. We present a surgical technical note in a patient with human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV-AIDS). He was diagnosed to have multi-drug-resistant (MDR) tuberculous spondylodiscitis, complicated with Immune reconstitution inflammatory syndrome (IRIS) and implant failure resulting in kyphosis and thoracic myelopathy. RCC with pharmacological management achieved healing and union, which was maintained at 4years follow-up. Our method of four-rod construct provides a strong and lasting construct in the management of spinal deformities and three-column osteotomies. It provides good structural support to the spine till bony union is achieved. Hybrid multi-rod construct like RCC provides a rigid mechanical support to the instrumentation and reduces the chances of rod failure especially in complex thoraco-lumbar spinal deformity correction surgeries.

The lateral entry point S2 alar-iliac (L-S2AI) screw: a preoperative computed tomography analysis of adult spinal deformity patients.

To radiographically compare lateral entry point S2-alar-iliac (L-S2AI) screw with conventional S2AI (C-S2AI) and conventional iliac screw (CIS) lengths and trajectories. Twenty-five preoperative CT scans of consecutive patients undergoing adult spinal deformity realignment surgery over a random 2-year period were analysed. Maximum in-bone length, caudal and lateral trajectories of CIS, C-S2AI, and L-S2AI screws were measured and compared using One-way ANOVA with Tukey's post hoc tests. Multivariate logistic regression was performed to identify predictors of high screw length discrepancy between C-S2AI and L-S2AI. Potential screw length was longest for CIS, followed by L-S2AI, then C-S2AI (114.5 ± 8.3mm vs 101.4 ± 9.6mm vs 80.6 ± 5.9mm, respectively) in all patients (p < 0.001). Actual screw lengths found both CIS and L-S2AI to be longer than C-S2AI (95.3 ± 8.5mm and 93.4 ± 7.5mm vs 82.1 ± 7.3mm; p = 0.008 and 0.003). Potential lateral angulation was smallest for CIS, followed by L-S2AI, then C-S2AI (21.9 ± 7.0° vs 31.9 ± 7.1° vs 40.9 ± 6.7°, respectively) in all patients (p < 0.001). L-S2AI and C-S2AI had the same caudal angulation (24.9 ± 6.8°), which was smaller than CIS (30.8 ± 5.8°) in all patients (p < 0.001). Univariate, but not multivariate analysis, revealed that lumbar lordosis > 40° (OR 7.2, p = 0.041), diagnosis of degenerative spondylolisthesis (OR 10.5, p = 0.017), and > 7 instrumented levels (OR 2.6, p = 0.049) were significantly associated with high screw discrepancies. The L-S2AI screw combines advantages of CIS and C-S2AI screws, which includes increased screw length, reduced lateral angulation, a low-profile screw head, ease of connection to proximal hardware, and the biomechanical advantage of a quadcortical purchase.

Dorsal or Lateral Approach for Intramedullary Nailing Using Kirschner Wire in Pediatric Radius Diaphyseal Fractures: Does it really matter?

Intramedullary nailing is the most preferred fixation method for diaphyseal radius and ulna fractures in the young age group. The aim of this study was to compare the dorsal and lateral entry points in the context of entry site-related complications, fracture union and functional results. This retrospective comparative study included pediatric patients who underwent surgery for isolated diaphyseal radius or both bone forearm fractures with intramedullary nailing using Kirschner wire between January 2013 and January 2019. K-wire was introduced from the distal radius through dorsal entry (Group A) in 19 patients and lateral entry (Group B) in 18 patients. The mean follow-up was 37months. Complications were noted and functional outcomes were evaluated according to the CHOP criteria. All fractures were healed. The functional results were determined to be excellent for 30, fair for 4, and poor for 3 patients. The overall complication rate was 18.9%, including distal radius fracture, mild pain in the wrist, and minor loss in ROM. No statistically significant differences were determined between the groups in respect of functional results and complication rates. Good functional results and similar complication rates can be obtained with both dorsal and lateral entry approaches. Stainless steel K-wire is an inexpensive intramedullary fixation implant option, which provides strong stabilization. Distal radius fracture is a newly reported complication for forearm intramedullary nailing. Leaving the implant out of the skin seems safe with the benefit of avoiding a further surgical intervention to extract the implant.

Incidência de dispersão peridural após bloqueio do plexo lumbar com técnica de Chayen: estudo retrospectivo

Background and objectivesThe lumbar plexus block (LPB) is a key technique for lower limb surgery. All approaches to the LPB involve a number of complications. We hypothesized that Chayen's approach, which involves a more caudal and more lateral needle entry point than the major techniques described in the literature, would be associated with a lower rate of epidural spread. MethodWe reviewed the electronic medical records and chart of all adult patients who underwent orthopedic surgery for total hip arthroplasty (THA) and hip hemiarthroplasty due to osteoarthritis and femoral neck fracture with LPB and sciatic nerve block (SNB) between January 1, 2002, and December 31, 2017, in our institute. The LPB was performed according to Chayen's technique using a mixture of mepivacaine and levobupivacaine (total volume, 25 mL) and a SNB by the parasacral approach. The sensory and motor block was evaluated bilaterally during intraoperative and postoperative period. ResultsA total number of 700 patients with American Society of Anesthesiologists (ASA) physical status I to IV who underwent LPB met the inclusion criteria. The LPB and SNB was successfully performed in all patients. Epidural spread was reported in a single patient (0.14%; p <0.05), accounting for an 8.30% reduction compared with the other approaches described in the literature. No other complications were recorded. ConclusionsThis retrospective study indicates that more caudal and more lateral approach to the LPB, such as the Chayen's approach, is characterized by a lower epidural spread than the other approach to the LPB.

Incidence of epidural spread after Chayen’s approach to lumbar plexus block: a retrospective study

Background and objectivesThe lumbar plexus block (LPB) is a key technique for lower limb surgery. All approaches to the LPB involve a number of complications. We hypothesized that Chayen's approach, which involves a more caudal and more lateral needle entry point than the major techniques described in the literature, would be associated with a lower rate of epidural spread. MethodWe reviewed the electronic medical records and chart of all adult patients who underwent orthopedic surgery for Total Hip Arthroplasty (THA) and hip hemiarthroplasty due to osteoarthritis and femoral neck fracture with LPB and Sciatic Nerve Block (SNB) between January 1, 2002, and December 31, 2017, in our institute. The LPB was performed according to Chayen’s technique using a mixture of mepivacaine and levobupivacaine (total volume, 25 mL) and a SNB by the parasacral approach. The sensory and motor block was evaluated bilaterally during intraoperative and postoperative period. ResultsA total number of 700 patients with American Society of Anesthesiologists (ASA) physical status I to IV who underwent LPB met the inclusion criteria. The LPB and SNB was successfully performed in all patients. Epidural spread was reported in a single patient (0.14%;p < 0.05), accounting for an 8.30% reduction compared with the other approaches described in the literature. No other complications were recorded. ConclusionsThis retrospective study indicates that more caudal and more lateral approach to the LPB, such as the Chayen’s approach, is characterized by a lower epidural spread than the other approach to the LPB.

Unilateral percutaneous kyphoplasty for lumbar spine: A comparative study between transverse process-pedicle approach and conventional transpedicular approach.

Anatomical differences of unilateral percutaneous kyphoplasty (PKP) between transverse process-pedicle approach (TPPA) and conventional transpedicular approach (CTPA) are not well discussed. To investigate the anatomical distinctions of unilateral PKP between TPPA and CTPA, we have discussed the unilateral PKP through a 3-dimensional-computed tomography database.Five hundred lumbar spines from 100 patients have been retrospectively collected and unilateral CTPA and TPPA were simulated. Distance between the entry point and the midline of the vertebral body (DEM), the puncture inclination angle (PIA), and the success rate (SR) of puncture were measured and compared.The male presented with significantly larger DEM than the female. The TPPA group presented with larger DEM than the CTPA group according to different level, the difference was 1.5 ± 1.1 mm to 3.8 ± 2.3 mm. The PIAs in the TPPA group were larger than that in the CTPA group. The SR including 1 side SR and bilateral SR was 72.0% in the CTPA group and 98.0% in the TPPA group. Compared with CTPA group, the SR in TPPA group was significantly higher for L1 to L4 no matter in the left, right side and female patients.The TPPA group presented with more lateral entry point, larger PIAs and higher SRs than that in the CTPA group. PKP surgery through a TPPA was safer and could provide a more symmetrical distribution of bone cement than the CTPA group.

Stereoencephalography Electrode Placement Accuracy and Utility Using a Frameless Insertion Platform Without a Rigid Cannula.

Implantation of depth electrodes to localize epileptogenic foci in patients with drug-resistant epilepsy can be accomplished using traditional rigid frame-based, custom frameless, and robotic stereotactic systems. To evaluate the accuracy of electrode implantation using the FHC microTargeting platform, a custom frameless platform, without a rigid insertion cannula. A total of 182 depth electrodes were implanted in 13 consecutive patients who underwent stereoelectroencephalography (SEEG) for drug-resistant epilepsy using the microTargeting platform and depth electrodes without a rigid guide cannula. MATLAB was utilized to evaluate targeting accuracy. Three manual coordinate measurements with high inter-rater reliability were averaged. Patients were predominantly male (77%) with average age 35.62 (SD 11.0, range 21-57) and average age of epilepsy onset at 13.4 (SD 7.2, range 3-26). A mean of 14 electrodes were implanted (range 10-18). Mean operative time was 144 min (range 104-176). Implantation of 3 out of 182 electrodes resulted in nonoperative hemorrhage (2 small subdural hematomas and one small subarachnoid hemorrhage). Putative location of onset was identified in all patients. We demonstrated a median lateral target point localization error (LTPLE) of 3.95 mm (IQR 2.18-6.23), a lateral entry point localization error (LEPLE) of 1.98 mm (IQR 1.2-2.85), a target depth error of 1.71 mm (IQR 1.03-2.33), and total target point localization error (TPLE) of 4.95 mm (IQR 2.98-6.85). Utilization of the FHC microTargeting platform without the use of insertion cannulae is safe, effective, and accurate. Localization of seizure foci was accomplished in all patients and accuracy of depth electrode placement was satisfactory.

The Results of Unstable Intertrochanteric Femur Fracture Treated with Proximal Femoral Nail Antirotation-2 with respect to Different Greater Trochanteric Entry Points.

Background Proximal femoral nail antirotation-2 (PFNA-2) has been widely used to treat intertrochanteric fractures with varied outcomes in the previous studies. The entry point of the nail plays an important role in achieving acceptable reduction, stable fixation, and avoiding implant related complications. This study was proposed to determine the optimal greater trochanteric entry point for PFNA-2 in unstable intertrochanteric femur fractures. Methods We conducted an observational study on 40 patients with unstable intertrochanteric fracture treated with PFNA-2 implant in a tertiary care hospital. The patients were grouped into two based on the entry point: group L for lateral and group M for medial entry. Randomization was carried out by assigning the patients to the group by alternate allocation. The quality of reduction, tip apex distance, Cleveland index, and all the complications were noted. The final follow-up was conducted at six months. The functional outcome was evaluated using modified Harris hip score. The data analysis was performed using Student's t-test, chi square test, and Mann–Whitney test. A P value below 0.05 was considered significant. Results Forty patients with 20 patients treated with medial entry point were included in group M and 20 patients in group L with lateral entry point. The group L had an average tip apex distance of 20.53 and group M had 20.02 (P=0.8). The complication of screw back out was seen in 3 out of 4 patients with poor reduction in group L. As per the Cleveland index, 6 patients in each group had suboptimal position and 4 out of 6 patients in group L with suboptimal position had screw back out. The lateral cortex impingement was seen in 14 patients of group L and 6 patients in group M with significant comparison (P=0.01). Three patients in group L had varus collapse with screw back out. Also, none in group M (0.05). The average modified Harris hip score in group L at six months follow-up was 71.94 and 76.8 in group M (P=0.84). Conclusion Overall, to achieve good quality of fixation and reducing damage to gluteus medius entry point for PFNA-2 should be 5 mm medial to the greater trochanter tip.

Combining Soil Erosion Modeling with Connectivity Analyses to Assess Lateral Fine Sediment Input into Agricultural Streams

Soil erosion causes severe on- and off-site effects, including loss of organic matter, reductions in soil depth, sedimentation of reservoirs, eutrophication of water bodies, and clogging and smothering of spawning habitats. The involved sediment source-mobilization-delivery process is complex in space and time, depending on a multiplicity of factors that determine lateral sediment connectivity in catchment systems. Shortcomings of soil erosion models and connectivity approaches call for methodical improvement when it comes to assess lateral sediment connectivity in agricultural catchments. This study aims to (i) apply and evaluate different approaches, i.e., Index of Connectivity (IC), the Geospatial Interface for Water Erosion Prediction Project (GeoWEPP) soil erosion model, field mapping and (ii) test a connectivity-adapted version of GeoWEPP (i.e., “GeoWEPP-C”) in the context of detecting hot-spots for soil erosion and lateral fine sediment entry points to the drainage network in a medium-sized (138 km2) agricultural catchment in Austria, further discussing their applicability in sediment management in agricultural catchments. The results revealed that (a) GeoWEPP is able to detect sub-catchments with high amount of soil erosion/sediment yield that represent manageable units in the context of soil erosion research and catchment management; (b) the combination of GeoWEPP modeling and field-based connectivity mapping is suitable for the delineation of lateral (i.e., field to stream) fine sediment connectivity hotspots; (c) the IC is a useful tool for a rapid Geographic Information System (GIS)-based assessment of structural connectivity. However, the IC showed significant limitations for agricultural catchments and functional aspects of connectivity; (d) the process-based GeoWEPP-C model can be seen as a methodical improvement when it comes to the assessment of lateral sediment connectivity in agricultural catchments.

Contralateral C7 to C7 nerve root transfer in reconstruction for treatment of total brachial plexus palsy: anatomical basis and preliminary clinical results.

OBJECTIVEContralateral C7 (CC7) nerve root has been used as a donor nerve for targeted neurotization in the treatment of total brachial plexus palsy (TBPP). The authors aimed to study the contribution of C7 to the innervation of specific upper-limb muscles and to explore the utility of C7 nerve root as a recipient nerve in the management of TBPP.METHODSThis was a 2-part investigation. 1) Anatomical study: the C7 nerve root was dissected and its individual branches were traced to the muscles in 5 embalmed adult cadavers bilaterally. 2) Clinical series: 6 patients with TBPP underwent CC7 nerve transfer to the middle trunk of the injured side. Outcomes were evaluated with the modified Medical Research Council scale and electromyography studies.RESULTSIn the anatomical study there were consistent and predominantly C7-derived nerve fibers in the lateral pectoral, thoracodorsal, and radial nerves. There was a minor contribution from C7 to the long thoracic nerve. The average distance from the C7 nerve root to the lateral pectoral nerve entry point of the pectoralis major was the shortest, at 10.3 ± 1.4 cm. In the clinical series the patients had been followed for a mean time of 30.8 ± 5.3 months postoperatively. At the latest follow-up, 5 of 6 patients regained M3 or higher power for shoulder adduction and elbow extension. Two patients regained M3 wrist extension. All regained some wrist and finger extension, but muscle strength was poor. Compound muscle action potentials were recorded from the pectoralis major at a mean follow-up of 6.7 ± 0.8 months; from the latissimus dorsi at 9.3 ± 1.4 months; from the triceps at 11.5 ± 1.4 months; from the wrist extensors at 17.2 ± 1.5 months; from the flexor carpi radialis at 17.0 ± 1.1 months; and from the digital extensors at 22.8 ± 2.0 months. The average sensory recovery of the index finger was S2. Transient paresthesia in the hand on the donor side, which resolved within 6 months postoperatively, was reported by all patients.CONCLUSIONSThe C7 nerve root contributes consistently to the lateral pectoral nerve, the thoracodorsal nerve, and long head of the triceps branch of the radial nerve. CC7 to C7 nerve transfer is a reconstructive option in the overall management plan for TBPP. It was safe and effective in restoring shoulder adduction and elbow extension in this patient series. However, recoveries of wrist and finger extensions are poor.