A Novel Surgical Landmark to Identify the Recurrent Laryngeal Nerve

Background: Although several surgical landmarks have been proposed to localize the recurrent laryngeal nerve (RLN), there is still no reliable landmark. Aims: To validate the reliability of a novel reference point at the intersection of the inferior border of the cricopharyngeal muscle and the inferior cornu of thyroid cartilage for locating the RLN. Study Design: Cadaver dissection study in the academic department of otolaryngology-head and neck surgery. Methods: Sixty-four RLNs in cadavers were assessed, and measurements of different surgical landmarks in conjunction with the proposed surgical landmark were obtained. Descriptive statistics, Pearson's chi-squared test, and Student's t-test were performed to analyze the data using GraphPad Prism (version 9.4.1; Dotmatics, Boston, Massachusetts, USA). Results: The average distance from the proposed landmark to the RLN was 2.3 ± 0.85 mm. The RLN was located just posterior to the reference point in 95.31% of the cadavers. The RLN passed under the inferior constrictor muscle in 90.63% of the cadavers. There was no statistically significant difference between right- and left-sided RLNs in terms of their relation with the reference point. Conclusion: The proposed reference point can be used as a reliable landmark to locate the RLN. This reference point may help surgeons during difficult thyroidectomy surgeries by providing an additional anatomical landmark.

Upper limb neurodynamic mobilization disperses intraneural fluid in cervical nerve roots: A human cadaveric investigation.

BACKGROUND: Cervical radiculopathy is a common cause of neck pain with resultant intraneural edema and impaired nerve function. One strategy to treat radiculopathy is neurodynamic mobilization (NDM); however, little is known about the effect of this treatment on nerve tissue fluid dynamics. OBJECTIVE: Investigate the impact of upper limb, median nerve-biased NDM on longitudinal intraneural fluid dispersion in the C5,C6,C7 nerve roots in un-embalmed cadavers. DESIGN: In situ repeated measures. METHODS: Human cadavers (n = 8) were dissected to expose and inject C5,C6,C7 cervical nerve roots with a dying agent. Initial longitudinal dye spread was recorded after dye spread stabilization. Cadavers were taken through 150 repetitions of upper limb, median nerve-biased NDM followed by dye spread re-measurement. Paired-samples t-tests with Bonferroni correction (α = 0.017) were used to compare pre-vs post-NDM dye spread measurements at C5,C6,C7 nerve roots; a one-way repeated measures ANOVA (α = 0.05) was used to examine differences between change scores for C5,C6,C7 nerve roots. RESULTS: Median nerve-biased NDM resulted in significant intraneural longitudinal dye spread at C5 and C6 nerve roots of 0.6 ± 0.6 mm and 3.4 ± 3.9 mm, respectively (p < 0.014). Dye spread was not significant at C7 nerve root (0.4 ± 0.7 mm). There was no between root difference in change of longitudinal dye spread between C5, C6, and C7 nerve roots. CONCLUSIONS: The results of this study show median nerve-biased NDM produced internal fluid movement within C5 and C6 cervical nerve roots. Results provide insight regarding possible mechanism of action and feasibility of NDM in treatment of patients with cervical radiculopathy.

Biomechanical Strength of a Novel Tendon Splicing Open Book Technique Compared to the Pulvertaft Method Using Unembalmed Human Cadaveric Tissue.

Background: Extensor pollicis longus (EPL) tendon rupture is a known complication of distal radius fractures. The Pulvertaft graft technique is currently used for tendon transfer of extensor indicis proprious (EIP) to EPL. This technique can produce unwanted tissue bulkiness and cosmetic concerns as well as hinder tendon gliding. A novel "open book" technique has been proposed, but relevant biomechanical data are limited. We designed a study to examine the biomechanical behaviours of the "open book" versus Pulvertaft techniques. Methods: Twenty matched forearm-wrist-hand samples were harvested from 10 fresh frozen cadavers (2 female, 8 male) with a mean age of 61.7 (±19.25) years. The EIP was transferred to EPL using the Pulvertaft versus "open book" techniques for each matched pair (sides randomly assigned). The repaired tendon segments were mechanically loaded using a Materials Testing System to examine graft biomechanical behaviours. Results: Mann-Whitney U test outcomes demonstrated that there was no significant difference between "open book" versus Pulvertaft techniques for peak load, load at yield, elongation at yield, or repair width. The "open book" technique demonstrated a significantly lower elongation at peak load and repair thickness, as well as significantly higher stiffness when compared with the Pulvertaft technique. Conclusions: Our findings support the use of the "open book" technique, producing comparable biomechanical behaviours compared to the Pulvertaft technique. Incorporating the "open book" technique potentially requires smaller repair volume, producing size and appearance that is more anatomic when compared with the Pulvertaft.

Contexte: La rupture du tendon du long extenseur du pouce (EPL - Extensor pollicis longus) est une complication connue des fractures distales du radius. La technique de greffe de Pulvertaft est actuellement utilisée pour un transfert tendineux de l'extenseur propre de l'index (EIP - extensor indicis proprious) à l'EPL. Cette technique peut produire une masse de tissu volumineuse non désirée et des préoccupations cosmétiques, mais aussi gêner le glissement du tendon. Une nouvelle technique en « livre ouvert ¼ a été proposée, mais les données biomécaniques pertinentes sont limitées. Nous avons conçu une étude visant à examiner les comportements biomécaniques de la technique « en livre ouvert ¼ comparativement à la technique de Pulvertaft. Méthodes: Vingt échantillons appariés avant-bras-poignet-main ont été prélevés sur 10 cadavres récemment congelés (2 femmes, 8 hommes) d'âge moyen 61,7 (± 19,25) ans. Les EIP ont été transférés aux EPL en utilisant la technique de Pulvertaft et la technique en livre ouvert pour chaque paire appariée (l'affectation du côté à chaque technique a été faite de manière aléatoire). Les segments tendineux réparés ont été chargés mécaniquement au moyen d'un système pour tester les matériaux afin d'étudier les comportements biomécaniques des greffes. Résultats: Les résultats du test U de Mann-Whitney ont montré qu'il n'y avait pas de différence significative entre la technique « en livre ouvert ¼ et la technique de Pulvertaft pour la charge maximum, la charge à la limite apparente d'élasticité, l'allongement à la limite apparente d'élasticité ou la largeur de réparation. La technique « en livre ouvert ¼ a démontré un allongement à la charge maximum et une épaisseur de réparation significativement moindres, ainsi qu'une significativement plus grande raideur, comparativement à la technique de Pulvertaft. Conclusions: Nos constatations étayent l'utilisation de la technique « en livre ouvert ¼ qui procure des comportements biomécaniques comparables à ceux de la technique de Pulvertaft. L'incorporation de la technique « en livre ouvert ¼ requiert potentiellement un plus petit volume de réparation, aboutissant à des dimensions et à un aspect plus anatomiques par rapport à la technique de Pulvertaft.

Correlation between thoracic kyphosis and dry needle length required to reach the pleural space needling the upper trapezius: A cadaveric fluoroscopic assessment.

BACKGROUND: It is unknown whether greater prone thoracic kyphosis increases pneumothorax risk during upper trapezius dry needling. OBJECTIVES: To fluoroscopically assess for a correlation between prone thoracic kyphosis and needle length required to reach the pleural space dry needling the upper trapezius in prone. DESIGN: Cadaveric study. METHODS: Prone thoracic kyphosis was assessed using dual bubble inclinometers. A 30 mm dry needle was inserted into the midsubstance of the upper trapezius perpendicular to the thoracic kyphosis. A single C-arm fluoroscopic image was obtained. This procedure was repeated with 40, 50, and 60 mm needles. Images were independently viewed by a radiologist to make a binary decision (yes vs. no) whether the needle had potentially broached the pleural space. RESULTS: Fifteen cadaveric specimens with a mean age of 74.9 ± 9.7 and mean kyphosis of 21.5° ±7.7 were used. A 30 mm needle never reached the pleural space. The pleural space was potentially broached on one, four and six occasions by the 40, 50, and 60 mm needle respectively. The correlation between needle depth penetration and kyphosis was not significant (r = 0.03, p = 0.93). Longer needles (50 and 60 mm) were significantly (p = 0.0049) more likely to reach the pleural space than shorter needles (30 and 40 mm). CONCLUSION: Thoracic kyphosis was not correlated with needle length required to reach the pleural space. Clinicians may consider selecting shorter needles (<40 mm) to mitigate potential risk while dry needling the upper trapezius in prone.

Influence of clinical experience on accuracy and safety of obliquus capitus inferior dry needling in unembalmed cadavers.

BACKGROUND: Suboccipital myofascial trigger points are common in tension-type headaches. OBJECTIVES: Compare the influence of clinical experience on the accuracy and safety of dry needle placement on the C2 laminar arch using a cranial-medial and caudal-medial technique to target obliquus capitus inferior in unembalmed cadavers. METHODS: Three physical therapists inserted three 50 mm dry needles, per technique, individually toward the C2 laminar arch targeting the obliquus capitus inferior. Ultrasound video of each trial was recorded, and an investigator trained in ultrasound interpretation and blinded to experience level recorded needling accuracy. RESULTS: The novice, experienced and expert clinicians were accurate on 73.8%, 59.5% and 71.4% of caudal-medial trials, and 14.3%, 16.7% and 66.7% of cranial-medial trials, respectively, with each clinician striking the spinal cord at least once. The expert clinician was 10 times more likely to accurately reach the C2 laminar arch using the cranial-medial direction than the experienced and novice clinicians. CONCLUSION: Increased clinical experience improved accuracy reaching the C2 laminar arch, with all investigators being more accurate with the caudal-medial technique. Greater experience did not eliminate risk as all investigators recorded at least one incident of striking the spinal cord. Fewer spinal cord strikes occurred with the cranial-medial than the caudal-medial technique.

THE CONSTRAINING EFFECT OF THE LATERAL FEMORAL INTERMUSCULAR SEPTUM ON PASSIVE HIP ADDUCTION IN UN-EMBALMED CADAVERS.

BACKGROUND: Due to the lack of verifiable iliotibial band elongation in response to stretching, the anatomical, biomechanical, and physiological responses to treatment of iliotibial band syndrome remain unclear. The lateral intermuscular septum, consisting of multiple myofibroblasts, firmly anchors the iliotibial band to the femur. PURPOSE AND HYPOTHESIS: The purpose of this in-situ study was to examine the constraining effect of the lateral intermuscular septum on available passive hip adduction range of motion in un-embalmed cadavers. It was hypothesized that an iliotibial band-septum-complex release would significantly increase passive hip adduction. DESIGN: Within-specimen repeated measures in-situ design. SETTING: Anatomy laboratory. METHODS: Metal markers were inserted into selected anatomical landmarks in eleven (11) un-embalmed human cadavers. With the specimen supine, the test-side lower limb was passively adducted until maximum passive hip adduction was reached. This movement was repeated three times each within two conditions: (1) band-septum-complex intact and (2) band-septum-complex dissected. Digital video of marker displacement was captured throughout each trial. Still images from a start and an end position were extracted from each video sequence. A custom Matlab program was used to calculate frontal plane hip adduction angle changes from obtained images. RESULTS: Mean change in passive hip adduction after band-septum-complex release was -0.3 ° (SD 1.6 °;95% CI: -1.33,0.76). A paired samples t-test revealed a non-significant difference (t=-.611; p=.555) in passive hip adduction for the band-septum-dissected condition (18.8 ± 3.9 °) versus the band-septum-intact condition (18.5 °±4.7 °). CONCLUSION: The lateral intermuscular septum does not appear to have a constraining effect on passive hip adduction in un-embalmed cadavers. Future research should evaluate the constraining effect of other selected tissues and conditions on hip adduction. Furthermore, inflammatory, metabolic, viscoelastic, and sensorimotor control properties within the iliotibial band in response to stretching should be investigated. LEVEL OF EVIDENCE: 3.

Accuracy and safety of dry needle placement in the piriformis muscle in cadavers.

OBJECTIVES: The purpose of this anatomic investigation is to (1) establish accuracy of dry needle placement into the medial third of the piriformis muscle as it exits the pelvis from the greater sciatic notch in unembalmed cadaveric specimens, while avoiding puncture of the sciatic nerve, and (2) establish guidelines for dry needle length selection. METHODS: Dry needles were placed in nineteen unembalmed cadaveric posterior hips. Dissection of the posterior hip musculature was performed to confirm location of the needle. A binary decision (yes/no) was made to determine whether the needle reached the piriformis muscle, went through the piriformis muscle, and/or pierced the sciatic nerve. Additionally, mean adipose tissue thickness, gluteus maximus muscle thickness, and perpendicular distance from the needle to the exiting sciatic nerve were recorded. RESULTS: The needle reached the medial third of the piriformis in 16 out of 19 hips (84.2% accuracy) and never punctured the sciatic nerve. There was a fair (r = 0.493) and good (r = 0.759) correlation between the needle length and the mean fat thickness for the left and right hips, respectively. DISCUSSION: A physical therapist was able to use bony landmark palpation to locate the piriformis muscle and use estimated adipose tissue thickness to choose a sufficient needle length to reach the medial third of the piriformis muscle. While the needle placement technique was safe and no sciatic nerve puncture occurred, the proximity of the piriformis muscle to the sciatic nerve warrants caution during needle placement. LEVEL OF EVIDENCE: 2c.