End Of Insertion Research Articles

A New Surface Anatomy Method for Locating the Axillary Nerve–the Clinical Safety Implications for Shoulder Procedures and Vaccinations

Background: It has previously been reported that the axillary nerve is located 5-7cm distal to the acromion. However, this simplistic description of the nerve’s location does not take into account how much variation there is in human anatomy and size between individuals. This study tested our hypothesis that irrespective of an individual’s anatomy and size, the axillary nerve is more accurately located halfway between the Distal end of the Deltoid insertion and the lateral edge of the acromion. Methods and Result: Authors dissected 12 fresh frozen cadaveric shoulders. The authors took various measurements and found that the axillary nerve was, as hypothesized, accurately and reliably located at the halfway point between the lateral border of the acromion and the deltoid insertion. Conclusion: This simple, accurate, and reliable method of predicting where the axillary nerve is located will assist surgeons and health practitioners who need to know where the axillary nerve is located, such as during shoulder procedures and vaccinations.

Molecular Mechanism of Ligand Binding to the Minor Groove of DNA

Although DNA–ligand binding is pervasive in biology, little is known about molecular-level binding mechanisms. Using all-atom, explicit-solvent molecular dynamics simulations in conjunction with weighted ensemble (WE)-enhanced sampling, an ensemble of 2562 binding trajectories of Hoechst 33258 (H33258) to d(CGC AAA TTT GCG) was generated from which the binding mechanism was extracted. In particular, the electrostatic interaction between the positively charged H33258 and the negatively charged DNA backbone drives the formation of initial H33258–DNA contacts. After this initial contact, a hinge-like intermediate state is formed in which one end of H33258 inserts into the minor groove of DNA. Following hinge state formation is a concerted motion whereby the second end of H33258 swings into the minor groove and the spine of hydration along the minor groove causing dehydration. This study illustrates how WE-enhanced simulations of biomolecular ligation processes can offer novel mechanistic insights by generating ensembles of binding events.

P105. Intraoperative CT based pedicle screw navigation in pediatric spine deformity increases operative time, radiation exposure with minimal impact on screw accuracy for experienced surgeon

P105. Intraoperative CT based pedicle screw navigation in pediatric spine deformity increases operative time, radiation exposure with minimal impact on screw accuracy for experienced surgeon

Ultrasound localization of central vein catheter tip by contrast-enhanced transthoracic ultrasonography: a comparison study with trans-esophageal echocardiography

BackgroundTo assess the usefulness of pre-operative contrast-enhanced transthoracic echocardiography (CE-TTE) and post-operative chest-x-ray (CXR) for evaluating central venous catheter (CVC) tip placements, with trans-esophageal echocardiography (TEE) as gold standard.MethodsA prospective single-center, observational study was performed in 111 patients requiring CVC positioning into the internal jugular vein for elective cardiac surgery. At the end of CVC insertion by landmark technique, a contrast-enhanced TTE was performed by both the apical four-chambers and epigastric bicaval acoustic view to assess catheter tip position; then, a TEE was performed and considered as a reference technique. A postoperative CXR was obtained for all patients.ResultsAs per TEE, 74 (67%) catheter tips were correctly placed and 37 (33%) misplaced. Considering intravascular and intracardiac misplacements together, they were detected in 8 patients by CE-TTE via apical four-chamber view, 36 patients by CE-TTE via epigastric bicaval acoustic view, and 12 patients by CXR. For the detection of catheter tip misplacement, CE-TTE via epigastric bicaval acoustic view was the most accurate method providing 97% sensitivity, 90% specificity, and 92% diagnostic accuracy if compared with either CE-TTE via apical four-chamber view or CXR. Concordance with TEE was 79% (p < 0.001) for CE-TTE via epigastric bicaval acoustic view.ConclusionsThe concordance between CE-TTE via epigastric bicaval acoustic view and TEE suggests the use of the former as a standard technique to ensure the correct positioning of catheter tip after central venous cannulation to optimize the use of hospital resources and minimize radiation exposure.

Advances and future directions in the care of patients with facial paralysis

Advances and future directions in the care of patients with facial paralysis

A Higher Initial Tensioning Force of an ACL Graft Results in a Higher Graft Force After Screw Fixation Irrespective of the Screw Diameter: A Biomechanical Study

Background: The intra-articular graft force (IAGF) in anterior cruciate ligament reconstruction decreases quickly over the first hours after surgery. Nevertheless, little is known about whether the initial extra-articular tensioning force (EATF) and screw diameter affect the graft force after fixation. Purpose: To investigate the effects of different EATFs on the IAGF of a soft tissue graft fixated via a bioabsorbable interference screw over 100 minutes after fixation and to evaluate the effects of different screw diameters within 1 mm of the tunnel width during this process. Study Design: Controlled laboratory study. Methods: In this biomechanical study, a porcine quadruple-strand soft tissue graft was inserted into the tibial anterior cruciate ligament tunnel. On the extra-articular side, 3 loads were applied during retrograde insertion of the bioabsorbable interference screw (6, 7, and 8 mm): 20 N, 80 N, and maximum manual EATF (Nmax). Nine study groups consisting of 10 tibiae each were created to test the effects of different EATFs and screw sizes. The IAGF was measured up to 100 minutes after the EATF was released. Results: An EATF ≥80 N resulted in a larger IAGF for all screw sizes at 100 minutes. There were no significant associations between the IAGF at 100 minutes and different screw diameters. Inserting the tibial screw significantly increased the IAGF in all groups, with the exception of Nmax applied in groups with 7- or 8-mm screws. When compared with the end of screw insertion, after the release of the EATF, the IAGF dropped by 55% to 77 % at 100 minutes. Conclusion: An initial EATF ≥80 N is associated with a significantly larger IAGF at 100 minutes in this cadaveric simulation. The IAGF in soft tissue grafts decreased substantially after the retrograde placement of an interference screw. A recommendation regarding screw diameter with respect to the IAGF cannot be given. Clinical Relevance: To obtain a higher residual graft force after bioabsorbable interference screw fixation, an initial EATF ≥80 N should be applied according to this model. The significant decrease in graft force after the release of the EATF indicates that the reconstructed knee cannot be mechanically stabilized after the surgery.

Otology/Neurotology

Introduction: We assess early hearing preservation (HP) outcomes of patients implanted with the new Slim 20 lateral wall array (CI624);compare early HP outcomes with and without real-time electrocochleography (RT-ECochG);and explain the role of RT-ECochG feedback to improve HP. We believe this abstract is suitable for a late-breaking abstract as we are the first to report early HP outcomes for a new Slim 20 lateral wall electrode (CI624). Since the CI624's release in May 2020, it is becoming increasingly popular among centers as a potential HP array. To our knowledge, there have not been any discussions at major conferences or published studies reviewing experiences with the CI624. Based on our early experience with 29 implantations using this electrode, we have found poor HP outcomes 1 month postoperatively with preservation in only 16 of the recipients. As a result, we began using real-time monitoring of cochlear health during the insertion (ie, electrocochleography [ECochG]) to potentially improve HP outcomes with the CI624. By using real-time ECochG (RT-ECochG) and particularly focusing on minimizing trauma at the end of insertion, we achieved superior early HP rates with this array (8/9 patients, 88.9%). Our preliminary data suggest that full insertion of the CI624 without ECochG results in unpredictable and relatively poor HP outcomes. We suspect that this is related to the CI624 being a longer electrode than previous hybrid arrays resulting in trauma to the apical-most hair cells and neural elements at full insertion. Thus, RT-ECochG may be required for predictable early HP using the CI624. As a result of the COVID-19 pandemic, we were unable to achieve sufficient implantations for submission of an abstract in January 2021. However, we have now performed 9 implants with the CI624 in the past 6 months using RT-ECochG for HP candidates. We believe that our experience with and without ECochG has resulted in an early critical finding that may influence how this implant is used in HP candidates. Methods: A longitudinal study was designed with postlinguistically deafened adults undergoing implantation with CI624 from 2020 to 2021. Pure-tone audiometry preoperatively and 1 month postoperatively were obtained. HP was defined as low-frequency pure-tone average (LFPTA;125, 250, 500 Hz) 5 μV ECochG response drop, array adjustments (ie, withdrawal ∼1 mm, 5° anti-modiolar rotation) were made to facilitate response recovery. Results: A total of 38 implants were performed. There was no scalar translocation on postoperative CT scans and mean apical insertion angle was 338.1° ± 86.4°. Full insertion was performed in most cases;however, partial insertion was performed if the RT-ECochG response dropped during insertion of the final 3 electrodes (n = 4). Of the 29 patients where RT-ECochG was not used, 16 (55.2%) had low-frequency HP postoperatively with preoperative LFPTA 42.4 ± 16.4 dB and threshold shift to 83.9 ± 27.8 dB. Among the 9 patients where RT-ECochG was used, 8 (88.9%) had low-frequency HP postoperatively with preoperative LFPTA 46.5 ± 16.0 dB and threshold shift to 62.6 ± 19.0 dB. Difference between threshold shift postoperatively with and without RT-ECochG was significant (P = .002, Mann-Whitney U test). Conclusion: RT-ECochG-guided insertion may be required for consistent HP outcomes following CI624 implantation. This may allow the surgeon to decide the depth of electrode insertion in the effort to preserve low-frequency hearing. Further investigation is needed to evaluate whether long-term HP can be maintained using CI624.

Extending Reach Inside the MRI Bore: A 7-DOF, Low-Friction, Hydrostatic Teleoperator

We present a hydrostatic teleoperator that provides physicians remote access inside the MRI bore and enables real-time MRI guided interventions such as liver biopsies. The device consists of a custom six-axis arm and a needle insertion end effector. The manipulator is passive and backdrivable with a near one-to-one mapping of motions and forces between the input and output. The six-axis arm translates and orients the needle during insertion and passively reflects respiratory motion while maintaining contact with the skin surface. Arm joints employ novel rotary rolling-diaphragms that provide stiff and low-friction rotational motion without the need for cables, belts, or gear mechanisms found in other solutions. We perform experiments to characterize the device's force and position tracking and demonstrate its functionality with path following tasks. Our results find a system roll-off frequency at 20Hz and that teleoperation tasks are performed comparably to holding the output directly. We motivate the need for force transparency in MRI guided biopsies with a user study in which five radiologists perform phantom membrane puncture biopsies using the needle insertion mechanism. The results indicate a 50% reduction in scans and a 14.5% decrease in membrane overshoot when force feedback is present.

Influence of Tool Path Strategies and Pocket Geometry on Surface Roughness in Pocket Milling

This paper discusses the effect of tool path strategies and pocket geometry to surface roughness due to pocket milling process. The machining processes have been performed on mould steel DF2 using carbide insert end mill as the cutting tool. The cutting parameters for this experiment were kept constant while the variables were cutting tool, path strategies and pocket geometries at three levels each. The effectiveness of different tool path strategy and different pocket geometry is evaluated in terms of measured surface roughness (Ra) of the workpiece. The grade of a pocket is directly proportional with its surface roughness. The lowest surface roughness measurement was produced by pocket geometry B with parallel spiral cutting tool path strategy.

Drainage Performance of a Novel Catheter Designed to Reduce Drainage Catheter Failure

Abstract Objective Efficient flow of fluids through drainage/infusion catheters is affected by surrounding tissue, organ compression, and scar tissue development, limiting or completely obstructing flow through drainage holes. In this work, we introduce a novel three-dimensional (3D) drainage catheter with protected side holes to reduce flow blockages. We then compare its drainage performance to standard straight and pigtail catheters using computer-generated catheter designs and flow analysis software. Methods Drainage performance was computed as flow rate through the catheter for a given pressure differential. Each catheter contained drainage holes on the distal (insertion) end and a single outlet (hub) hole open to atmosphere. Computational fluid dynamics using ANSYS AIM 18.2 was used to simulate flow through the catheter and examine drainage performance based on variations to the following parameters: (1) side hole shape, (2) cross-sectional area of the catheters, (3) number of side holes, and (4) cross-sectional area of the side holes. Results Drainage through the newly introduced catheter in all simulations was nearly identical to standard pigtail and straight catheters. While working to optimize the 3D catheter design, we found that the changes in side hole shape and side hole cross-sectional area had little effect on the total flow rate through the catheters but had a large impact on flow rate through the side hole nearest to the hub (proximal hole). Additionally, the majority of flow in all catheters occurred at the most proximal 1 to 3 side holes closest to hub, with relatively little flow occurring at side holes more distally located (closest to insertion end). The 3D catheter demonstrated no changes in flow characteristics when the coiled segment was occluded, giving it an advantage over other catheter types when the catheter is compressed by surrounding tissue or other external obstruction. Conclusions The majority of fluid flow in catheters with a diameter of 4.67 mm (14 Fr) or smaller occurred at the most proximal 1 to 3 side holes. A novel 3D coiled catheter design can protect these proximal holes from external blockage while maintaining drainage performance compared with standard straight and pigtail catheters.

Radiographic Evaluation of the Bone Remodeling on Tilted Osseointegrated Implants: Follow-up at 1 Year

The purpose of this study was to evaluate the degree of vertical peri-implant resorption around implants inserted with an inclination increased more than 10° at a distance of at least 1 year from insertion. For the realization of the study, a sample consisting of 47 patients for a total of 115 implants was selected. We excluded all those subjects whose conditions could have compromised the outcome of the treatment. An orthopantomography of the dental arches was made using Orthophos XG 3D Sirona at time T0 (at the end of definitive insertion of prosthesis) and at time T1 (at least 1 year after T0) with the aim of an individualized positioner. In this study, all the implants with inclination equal to or greater than 10° were subdivided into three groups, and the implants with inclination between 0 and 10 were used as control sample. In group I, there is a statistically significant difference in at least one of the two sides (distal one) between T0 and T1. In groups II and III, there is a statistically significant difference in the degree of bone resorption on the mesial side with respect to distal side. In group IV, a statistically significant difference on both sides was evidenced. The implant survival at a distance of 1 year was equal to 100% of cases. Surgeons must take into account the possibility that an increase in inclination of implants may lead to a more rapid resorption of bone mesially or distally. The direction of the prosthetic load transmitted to the fixture is a variable that could influence the degree of reabsorption of both mesial and distal bone structures according to both laboratory and clinical data.

Quantitative Magnetic Resonance Imaging Analysis of the Common Site of Acute Achilles Tendon Rupture: 5 to 8 cm Above the Distal End of the Calcaneal Insertion

Background: Previous studies have not quantitatively analyzed the site of acute Achilles tendon rupture. Purpose: To investigate the site of acute Achilles tendon rupture via magnetic resonance imaging (MRI). Study Design: Cross-sectional study; Level of evidence, 4. Methods: The medical records and MRIs of 195 patients with acute Achilles tendon rupture were retrospectively reviewed. The rupture site was measured as the distance from the most distal fibers of the Achilles tendon at the calcaneal insertion to the proximal end of the distal stump. The relationship between the site of rupture and patient characteristics was analyzed, and the intra- and interobserver reliability of the measurements was assessed using intraclass correlation coefficients. Results: The rupture site had a mean distance of 6.4 cm (SD, 1.5) and the 10th to 90th percentile range was 5.0 to 8.4 cm. There was no significant difference in location of the rupture according to patient characteristics and the time of imaging. The intra- and interobserver reliability of measurements was excellent. Conclusion: Most acute Achilles tendon ruptures visible on MRI occurred 5 to 8 cm above the distal end of the calcaneal insertion, which is more proximal than the previously reported 2 to 6 cm location.

Retroperitoneal Approach for Ureteropelvic Junction Obstruction: Encouraging Preliminary Results With Robot-Assisted Laparoscopic Repair.

Introduction stating the aim of the study: Robot-assisted laparoscopic pyeloplasty (RALP) is gaining acceptance among pediatric urologists. Few studies have evaluated the retroperitoneal approach for RALP. We share our experience from the first 2 years of a multidisciplinary pediatric robotic program in our center.Patients (or Materials) and Methods: We performed a retrospective analysis of prospectively collected data of children undergoing RALP for ureteropelvic junction obstruction (n = 50). Diagnosis was confirmed by ultrasound and Tc-99m mercaptoacetyltriglycine renal scan or MRI; the same criteria were used to evaluate outcome. Surgical approach was chosen according to a specific algorithm. Transperitoneal approach (n = 13) was reserved for horseshoe kidney, ectopic kidney, and redo surgery. We analyzed the 37 cases performed by a lateral retroperitoneal approach. Dismembered pyeloplasty was done for all cases and anastomosis was performed using a running monofilament 6/0 absorbable suture. All were drained by double J stent. Patient data, operating room parameters and postoperative course were recorded.Results: The median age was 7.9 years (5.1–13.8); the youngest was 2 years old. The median weight was 23 kg (17–41) with the smallest weighing 12.4 kg. Aberrant crossing vessels were present in 18 children. Median set-up time, from skin incision until the end of the 4-port insertion, was 33 min (29–48). Median surgeon's console time was 151 min (136–182). No conversion to an open procedure was necessary. The postoperative course was free of complications, except urinary tract infection in 6 children. All but 4 patients were discharged on day one. Median follow-up was 9 months (5–13). Redo pyeloplasty was not required. Practical training of other colleagues was possible after 10 cases performed by the same surgeon.Conclusion: These preliminary results suggest that retroperitoneal RALP in children is feasible, safe and effective. It is an excellent option with ideal anatomical exposure. Longer term results as well as continued practice will identify and overcome any challenges and enable surgical mastery of this procedure which is still evolving.

Insertion of a preloaded Monoka™ stent for congenital nasolacrimal obstruction: Intraoperative observations. A preliminary study

To study the intraoperative deployment of a pre-loaded probe for a "pushed" monocanalicular nasolacrimal intubation. Non-randomized study of consecutive cases. Description: A classical Monoka™ silicone stent with the silicone tube attached at right angles to the punctal plug is contained entirely inside an introducer connected to a piston. Insertion: The procedure begins with intubation of the nasolacrimal duct with the metallic introducer. Traction on the piston retracts the metallic introducer inside the handpiece. This relative shortening progressively ejects the stent, starting with its free end at the bottom of the introducer. The operation was observed endoscopically under single-blind conditions. Twenty-eight preloaded Monoka™ stents were placed consecutively, in 28 congenital nasolacrimal duct intubations in 22 patients (28 sides). Endoscopic examination showed that the free part of the stent was progressively ejected from the introducer during retraction of the piston. Insertion of this pushed stent into the nasal cavity was effective in 23/28 cases (82.1%). A total of 28 preloaded stent insertions were attempted and 23 were correctly deployed. At the end of nasolacrimal duct intubation, contact between the punctal plug and the lacrimal punctum was problematic in four cases (4/28=14.2%). At the beginning of stent placement, premature ejection of the punctal plug within the end of the introducer occurred in five cases (5/28=17.8%). These five stents failed to insert properly into the nasal cavity. At the end of insertion, retention of the punctal plug in the introducer occurred in two cases (2/28=7.1%). No cases of intraoperative or postoperative epistaxis were observed. Intraoperative nasal endoscopy validated the concept of the preloaded Monoka stent and its deployment. Reproducibility and improved reliability may require a change in stenting technique and a design modification.

Last Scene Underground: An Ethnographic Novel of Iran

Last Scene Underground: An Ethnographic Novel of Iran

Response Changes During Insertion of a Cochlear Implant Using Extracochlear Electrocochleography

Electrocochleography is increasingly being utilized as an intraoperative monitor of cochlear function during cochlear implantation (CI). Intracochlear recordings from the advancing electrode can be obtained through the device by on-board capabilities. However, such recordings may not be ideal as a monitor because the recording electrode moves in relation to the neural and hair cell generators producing the responses. The purposes of this study were to compare two extracochlear recording locations in terms of signal strength and feasibility as intraoperative monitoring sites and to characterize changes in cochlear physiology during CI insertion. In 83 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then at an extracochlear position-either adjacent to the stapes or on the promontory just superior to the RW. Recording from the fixed, extracochlear position continued during insertion of the CI in 63 cases. Before CI insertion, responses to low-frequency tones at the RW were roughly 6 dB larger than when recording at either extracochlear site, but the two extracochlear sites did not differ from one another. During CI insertion, response losses from the promontory or adjacent to the stapes stayed within 5 dB in ≈61% (38/63) of cases, presumably indicating atraumatic insertions. Among responses which dropped more than 5 dB at any time during CI insertion, 12 subjects showed no response recovery, while in 13, the drop was followed by partial or complete response recovery by the end of CI insertion. In cases with recovery, the drop in response occurred relatively early (<15 mm insertion) compared to those where there was no recovery. Changes in response phase during the insertion occurred in some cases; these may indicate a change in the distributions of generators contributing to the response. Monitoring the electrocochleography during CI insertion from an extracochlear site reveals insertions that are potentially atraumatic, show interaction with cochlear structures followed by response recovery, or show interactions such that response losses persist to the end of recording.

“Pin the Tail on the MPFL” Identification by Palpation - Results

Objectives:Medial patellofemoral ligament (MPFL) reconstruction has become increasingly popular to treat patellar dislocation. Studies have noted the importance of recovering the anatomic insertion of the MPFL and that reconstruction should be performed within 5mm of the native insertion site to avoid biomechanical complications. Currently radiographic imaging is used to locate the MPFL insertion site at Schottle’s point. This study investigated the viability of utilizing palpation to locate the MPFL insertion site for proper MPFL reconstruction.Methods:Thirty-eight patellofemoral specialists attending IPSG were selected to participate in this study with a mean of 15.9 years in practice (median 14, range 1-39). Using a single fresh-frozen human cadaveric knee, each specialist individually performed surface palpation of the anatomical landmarks and inserted a dissection pin at the purposed MPFL femoral insertion site. Radiographic images were taken of each pin placement. At conclusion, the cadaveric leg was dissected and forceps were placed at the distal and proximal end of the MPFL insertion with a dissection pin in the middle of the insertion and a radiographic image was taken of this. Images were analyzed using ImageJ software to determine the distance and angle from the MPFL insertion center to the specialist’s pin location.Results:Length and angle measurements were taken three times and averaged for each sample. The bridge of a forceps was utilized as a scale for the images (2.325 pixels/mm). Average distance was found to be 3.18 ± 2.55 mm with an average angle of 161.2 ± 74.4° relative to the anterior direction indicating 0°. Seven of thirty-eight (18%) samples were more than 5mm from the native insertion site.Conclusion:With an average pin displacement of 3.18mm, it was seen that most specialists could accurately determine MPFL insertion location accurately without the use of radiographic equipment. On average, the displacement angle of 161.2° indicates the pin was typically located more posterior than the MPFL insertion site. Seven measurements exceeded 5mm distance from the MPFL insertion, which would be concerning for biomechanical effects on the patellofemoral joint if the repair was placed at the pin location.Clinical Relevance:While experienced patellofemoral surgeons were able to identify femoral MPFL origin with reasonable accuracy by palpation, even experienced surgeons had inaccuracies that could compromise outcomes up to 18% of the time. For this reason we recommend the use of radiography along with appropriate exposure to assist in accurately identifying the anatomic femoral attachment of the MPFL during MPFL reconstruction.

Combined resection-recession versus combined recession-retroequatorial myopexy of medial rectus muscles for treatment of near-distance disparity Esotropia.

PurposeTo compare and evaluate the efficacy of two different surgical techniques for the treatment of near-distance disparity esotropia; combined resection–recession and recession–retroequatorial myopexy of medial rectus muscles.Patients and methodsThis prospective study included 28 patients diagnosed with convergence excess esotropia who had worn their full cycloplegic refraction and/or bifocal glasses for at least 6 months and still had near-distance disparity esotropia. The patients were divided into 2 groups; Group I underwent combined bimedial rectus muscles resection 2.5 mm from the insertion end with recession based on near-angle esotropia according to current surgical tables with 1 mm add of recession for each muscle, while Group II underwent bimedial recession based on far angle combined with retroequatorial myopexy at 13–14 mm from insertion. A satisfactory result was defined as orthophoria or esotropia <10 prism diopters (Δ) at near and distance with reduction of the near-distance disparity to <10 Δ. The patients were followed up for at least 2 years for stability of correction and late onset consecutive exotropia.ResultsIn Group I, all the patients had satisfactory alignments at near and far with residual near–far disparity #10 Δ, no cases of overcorrection at far was reported; while in Group II, all cases had orthophoria at far, but 4 cases (28.6%) showed near–far disparity >10 Δ.ConclusionThe technique of combined resection–recession is safe, easy and more effective in the treatment of near-distance disparity esotropia regardless of the level of accommodative convergence/accommodation ratio, with stability of results though longer follow-up period is still needed.

A cadaveric biomechanical study comparing the ease of femoral nail insertion: 1.0- vs 1.5-m bow designs

Anatomic fit of intramedullary nails was suggested by previous studies to improve significantly when the nail radius of curvature (ROC) is closer to the average femoral anatomy. However, no attempt has been made to investigate the impact of different ROC designs on the nail insertion process. Therefore, this biomechanical study quantitatively compared the ease of insertion between femoral intramedullary nails with a 1.0-m and a 1.5-m bow radius. Long TFN-ADVANCED™ (TFNA, 1.0m ROC) and Proximal Femoral Nail Antirotation nails (PFNA, 1.5m ROC) were implanted pairwise into seven paired cadaver femora. All bones were reamed 1.5mm larger than the nail diameter. Using a material testing machine, intramedullary nailing was then performed stepwise with 20-mm steps and a 10-mm/s insertion rate, and force was measured. The nail deformation caused by the insertion was assessed through 3D computer models built from pre- and post-nailing CT scans. The ease of insertion between TFNA and PFNA nails was quantified in terms of insertion force, insertion energy and nail deformation. There was no significant difference in the peak force generated during nailing between TFNA and PFNA nails (P = 0.731). However, the force measured at the end of insertion (P = 0.002) was significantly smaller in TFNA nails compared to PFNA nails. After implantation, TFNA nails showed significantly smaller deformation when compared to PFNA nails (P = 0.005, both ends aligned). Furthermore, less energy was required to insert TFNA nails; however, the difference was not significant (P = 0.25). Compared to PFNA nails, a significant decrease in insertion force and nail deformation was found at the end of insertion for TFNA nails. Results suggest that TFNA having a 1.0-m ROC is easier to insert for the set of femora used in this study compared to PFNA with a 1.5-m ROC.

Ridge at the medial rectus muscle insertion: A new anatomical landmark.

Background and Aim:Rectus muscle insertions are usually linear or slight curved with the anterior convexity. While operating squint surgeries, we found a presence of ridge-like structure at the medial rectus insertion. None of the other rectus muscle insertions had such structure.Materials and Methods:Patients undergoing squint surgery were included in the study. All the patients had negative forced duction test for all the gazes and had comitant strabismus. The patients underwent surgery through the fornix route. All the squint surgeries were primary. None of the patients undergoing resurgery were included in the study. The ridge seen is actually an elevated curved structure and shows discontinuation of the actual medial rectus insertion. The measurements were taken from the superior and inferior end of the medial rectus muscle insertion.Results:In a total of 76 medial rectus surgery (for recession or resection), we found the ridge was present in 68 (89.5%) of cases. The ridge was located at an average distance of 6.33 ± 1.5 mm inferior and 3.82 ± 0.9 mm superior to the superior and inferior point of medial rectus insertion, respectively.Conclusion:We describe the presence, morphology, and measurements of a ridge as an anatomical landmark at medial rectus insertion.