Analysis of Mechanoreceptors and Free Nerve Endings of the Transverse Carpal Ligament.

Background: The treatment of carpal tunnel syndrome (CTS) by sectioning the transverse carpal ligament (TCL) is not exempt from complications. Some nerve branches may be damaged by the incision. The aim of this study is to identify and map the TCL nerve endings, serving as a guide for sectioning this structure in a zone with less nerve ending density. Methods: Ten TCLs were obtained from fresh frozen cadavers. The TCLs were measured, divided into 3 equal bands (radial, central, and ulnar), and submitted to cryostat sectioning. The sections were subjected to immunofluorescence with the protein gene product (PGP) 9.5 and confocal microscopy analysis. Results: All the specimens contained type I and type IV mechanoreceptors. Neural elements occupied 0.695 ± 0.056% of the ligament area. The density of the neural elements was greater in the radial, followed by the ulnar and central bands, with 0.730 ± 0.083%, 0.686 ± 0.009%, and 0.669 ± 0.031%, respectively. Conclusion: The present findings suggest that the region with the least potential for neural element injury during TCL release is the central third near the transition with the ulnar third. When performed distally to proximally with a slight inclination from the radial to the ulnar, this release compromises the lowest nerve element density. Topographically, the proximal limit of the release is the distal wrist crease, while the distal limit is the intersection of Kaplan cardinal line and the axis of the third webspace.

Development of a 3D-immunofluorescence analysis for sensory nerve endings in human ligaments.

BACKGROUND: The analysis of ligamentous mechanoreceptors is difficult due to a high amount of unclassifiable mechanoreceptors, which result from incomplete visualization through limited microscopic techniques. NEW METHOD: The method was developed using dorsal intercarpal ligaments and dorsal regions of the scapholunate interosseous ligament from human cadaver wrists. Consecutive 70 µm thick cryosections were stained with immunofluorescence markers for protein S100B, neurotrophin receptor p75 (p75), protein gene product 9.5 (PGP 9.5) and 4',6-diamidino-2-phenylindole (DAPI). 3D images of sensory nerve endings were obtained using a confocal laser scanning microscope. Experimental point spread functions (PSF) were used to deconvolve images. Sensory nerve endings were localised in each section plane and classified according to Freeman and Wyke. Finally, confocal data was visualized as 3D-images. RESULTS: The method produced excellent image quality, revealing detailed three-dimensional structures. The created 3D-model of sensory nerve endings could be analyzed in all three dimensions, augmenting visualization of the form and immunoreactive pattern of sensory nerve endings. Deconvolution with experimentally measured PSFs aided in enhancing image quality. COMPARISON WITH EXISTING METHODS: Using a triple immunofluorescent staining method allows to visualize the structure of sensory nerve endings more precisely than techniques with serial analysis of different monostaining of neural markers. Imaging in three dimensions enhances morphologic details, which are limited in 2D-microscopy. CONCLUSION: 3D-triple immunofluorescence produces high quality visualization of mechanoreceptors, thereby improving their analysis. As an elaborate technique, it is ideal for defined research questions concerning the microstructure of sensory nerve endings.

Sensory innervation of the human elbow joint and surgical considerations.

Based on the currently available literature, total denervation of the elbow joint is considered impossible. However, consensus with respect to the anatomic location of sensory branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches innervating the elbow joint, as well as the distribution of sensory receptors about its capsule. Four electronic databases were queried, between January 1945 and June 2019. Twenty-one original articles providing a detailed description of the distribution of sensory receptors about the elbow joint capsule (5) and its articular branches (16) were reviewed. The posterior capsule was found to be primarily innervated by the ulnar and radial nerves via combined articular branches and sensory branches of the medial antebrachial cutaneous nerve. The anterior capsule was found to be primarily innervated by a plexus of articular ramifications from muscular branches of mixed nerves (ulnar, musculocutaneous, radial, and median nerves). A higher density of nociceptors and mechano-receptors was identified within the posterior and anterior capsules, respectively. Thorough denervation, via the technique proposed herein, is likely to be sufficient in eliminating pain from degenerative conditions of the elbow joint.

Report of a Transligamentous Ulnar Nerve Sensory Branch.

Background: Several anatomical variations of the median nerve recurrent motor branch have been described. No previous reports have described the anatomical variation of the ulnar nerve with respect to transverse carpal ligament. In this article, we present a patient with symptomatic compression of the ulnar nerve found to occur outside the Guyon canal due to a transligamentous course through the distal transverse carpal ligament. Methods: A 59-year-old, right-hand-dominant male patient presented with right hand pain, subjective weakness, and numbness in both the ulnar and the median nerve distributions. Electromyography revealed moderate demyelinating sensorimotor median neuropathy at the wrist and distal ulnar sensory neuropathy. At the time of planned carpal tunnel and Guyon canal release, a transligamentous ulnar nerve sensory common branch to the fourth webspace was encountered and safely released. Results: There were no surgical complications. The patient's symptoms of numbness in the median and ulnar nerve distribution clinically improved at his first postoperative visit. Conclusions: We have identified a case of transligamentous ulnar nerve sensory branch encountered during carpal tunnel release. To our knowledge, this has not been previously reported. While the incidence of this variant is unknown, hand surgeons should be aware of this anatomical variant as its location puts it at risk of iatrogenic injury during open and endoscopic carpal tunnel release.

Study of the Nerve Endings and Mechanoreceptors of the Anterolateral Ligament of the Knee.

PURPOSE: To describe the morphology and distribution of the anterolateral ligament of the knee (ALL) nerve endings, aiming to understand the interaction between the proprioceptive system and knee mechanics. METHODS: Twenty ALLs were obtained from fresh frozen cadavers. The ligaments were measured, weighed, and cut. Sections (10 µm) were prepared in hematoxylin and eosin-stained slides to analyze tissue integrity, and 50-µm sections were subjected to immunofluorescence with the protein gene product 9.5 as primary antibody and Alexa Fluor 488 as secondary antibody, followed by microscopic analysis. RESULTS: The ALL was identified in 100% of the dissections, exhibiting a mean (± standard deviation) length of 4.0 ± 0.4 cm, a mean width of 5.5 ± 0.8 mm, and a mean weight of 0.9 ± 0.2 g. The histological sections in hematoxylin and eosin showed dense, well-organized collagen and the presence of vascular tissue. All the specimens analyzed contained type I (Ruffini-like) mechanoreceptors and free nerve endings (type IV), varying from parallel to intertwined fibers. Unclassified nerve endings with different irregular shapes were also found. The neural elements occupied 0.6% ± 0.3% of the ligament area, and most were observed near the origin of ALL insertions. CONCLUSION: The ALL exhibits a peripheral nerve structure, primarily type I and IV mechanoreceptors. These findings suggest that the ALL is important for the proprioception and anterolateral stabilization of the knee. CLINICAL RELEVANCE: It is important to understand ALL innervation and infer how an injury could compromise the proprioceptive role of the lateral compartment, as the ligaments contribute dynamically to stability through proprioceptive control of muscle forces. The findings confirm that the ALL is highly innervated by mechanoreceptors and may have a proprioceptive role in conjunction with the lateral collateral ligament in the lateral region of the knee.

Ultrasound-Guided Versus Landmark-Based Approach to the Distal Suprascapular Nerve Block: A Comparative Cadaveric Study.

PURPOSE: To compare the accuracy of distal suprascapular nerve (dSSN) blockade performed with the use of ultrasound-guided regional anesthesia (USRA) versus with a landmark-based approach (LBA). A secondary aim was to describe the anatomic features of the sensory branches of the dSSN. METHODS: USRA and LBA were performed in 15 shoulders each from 15 cadavers (total of 30 shoulders). Then, 10 mL of methylene blue‒infused ropivacaine 0.75% was injected into the dSSN. Simultaneously, 2.5 mL of red latex solution was injected to identify the position of the needle tip. The division and distribution of the sensory branches originating from the SSN were described. RESULTS: The tip of the needle was identified at 1.3 cm (range, 0-5.2 cm) and 1.5 cm (range, 0-4.5 cm) with USRA and the LBA, respectively (P = .90). Staining diffused past the origin of the most proximal sensory branch in 27 cases. The most proximal sensory branch arose 2.5 cm from the suprascapular notch. Among the 3 failures that occurred in the USRA group, the sensory branches also failed to be marked. All 30 dSSNs gave off 3 sensory branches, which innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments. CONCLUSIONS: An LBA is as reliable and accurate as US guidance for anesthetic blockade of the dSSN. Marking of the suprascapular nerve must be proximal to the suprascapular notch to involve the 3 sensory branches in the anesthetic blockade. CLINICAL RELEVANCE: The present study demonstrates that a landmark-based approach to anesthetic blockade of the distal suprascapular nerve is accurate and can be performed by orthopaedic surgeons lacking experience in ultrasound-guided anesthetic techniques.

Sensory innervation of the subacromial bursa by the distal suprascapular nerve: a new description of its anatomic distribution.

BACKGROUND: Sensory innervation to the shoulder provided by the distal suprascapular nerve (dSSN) remains the subject of debate. The purpose of this study was to establish consensus with respect to the anatomic features of the sensory branches of the dSSN. The relevant hypothesis was that the dSSN would give off 3 sensory branches providing innervation to the posterior glenohumeral (PGH) capsule, the subacromial bursa, in addition to the coracoclavicular and acromioclavicular ligaments. METHODS: The division, course, and distribution of the sensory branches that originated from the dSSN and innervated structures around the shoulder joint were examined macroscopically by dissecting 37 shoulders of 19 fresh-frozen cadavers aged of 83.0 years (range, 74-98 years). RESULTS: The 37 dSSN provided 1 medial subacromial branch (MSAb), 1 lateral subacromial branch (LSAb), and 1 PGH branch (PGHb) to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular (MSAb and LSAb) and coracoclavicular (MSAb) ligaments, as well as the PGH capsule (PGHb). CONCLUSIONS: The dSSN provided 2 subacromial branches and 1 PGHb to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular and coracoclavicular ligaments, as well as the PGH capsule.

Distal suprascapular nerve block-do it yourself: cadaveric feasibility study.

BACKGROUND: A bone landmark-based approach (LBA) to the distal suprascapular nerve (dSSN) block is an attractive "low-tech" method available to physicians with no advanced training in regional anesthesia or ultrasound guidance. The primary aim of this study was to validate the feasibility of an LBA to blockade of the dSSN by orthopedic surgeons using anatomic analysis. The secondary aim was to describe the anatomic features of the sensory branches of the dSSN. MATERIALS AND METHODS: An LBA was performed in 15 cadaver shoulders by an orthopedic resident. Then, 10 mL of methylene blue-infused 0.75% ropivacaine was injected around the dSSN; 2.5mL of red latex solution was also injected to identify the position of the needle tip. The division and distribution of the sensory branches that originate from the suprascapular nerve were described. RESULTS: The median distance between the dSSN and the site of injection was 1.5 cm (0-4.5 cm). The most common injection site was at the proximal third of the scapular neck (n = 8). Fifteen dSSNs were stained proximal to the origin of the most proximal sensory branch. All 15 dSSNs gave off 3 sensory branches that innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments. CONCLUSIONS: An LBA for anesthetic blockade of the dSSN by an orthopedic surgeon is a simple, reliable, and accurate method. Injection close to the suprascapular notch is recommended to involve the dSSN proximally and its 3 sensory branches.

Lateral Knee Compartment Portals: A Cadaveric Study Defining a Posterolateral Viewing Safety Zone.

PURPOSE: This study attempted to define a reproducible "safe zone" based on extra- and intra-articular knee anatomy for placing one or 2 accessory portals in the lateral tibiofemoral compartment for posterolateral region viewing. METHODS: Standard portals were created in 10 cadaveric knees to enable posterolateral region arthroscopic lateral tibiofemoral joint compartment viewing. After identifying the lateral knee surface tissue "soft spot," an accessory posterolateral portal (A) was created using an 18-gauge spinal needle and 4-mm cannula under direct visualization of a 70° arthroscope through the anteromedial portal. A second accessory portal (B) was then created 1 cm posterior and 1 cm superior to portal A. Accessory portal locations were measured relative to capsular fold and popliteus tendon locations. Distances from the peroneal nerve, lateral collateral ligament, popliteus tendon, and the biceps tendon were determined. Statistical analysis compared portal location differences from key anatomical structures (P < .05). RESULTS: Accessory portal A (mean ± 95% confidence interval) was located 8.8 ± 2.7 mm from the popliteus tendon, 11.6 ± 2.7 mm from the lateral collateral ligament (LCL), 26.8 ± 2.3 mm from the peroneal nerve, and 4.9 ± 2.5 mm from the biceps tendon. Accessory portal B was located 17.3 ± 2.8 mm from the popliteus tendon, 20 ± 2.8 mm from the LCL, 30.3 ± 3.3 mm from the peroneal nerve, and 7.0 ± 4.8 mm from the biceps tendon. Accessory portal B was located a greater distance from the LCL and the popliteus tendon than portal A (P < .0001). CONCLUSIONS: Using intra- and extra-articular anatomic landmarks, both accessory portals could be safely placed in the lateral tibiofemoral joint compartment to enable posterolateral region viewing. Accessory portals used individually or in combination may enable easier posterolateral region viewing for arthroscopic repair of lateral tibiofemoral compartment structures. CLINICAL RELEVANCE: Lateral tibiofemoral compartment portals can be safely created to enable improved visibility for complex arthroscopic procedures in the posterolateral viewing region.

Anatomic Relationship Between the Hook of the Hamate and the Distal Transverse Carpal Ligament: Implications for Ultrasound-Guided Carpal Tunnel Release.

OBJECTIVE: During ultrasound-guided carpal tunnel release, osseous landmarks may supplement direct visualization of the distal transverse carpal ligament (dTCL) to ensure a complete release. The purpose of this study was to determine the relationship between the apex of the hook of the hamate (aHH) and the dTCL within the transverse safe zone (TSZ) of the carpal tunnel. DESIGN: Twenty unembalmed cadaveric specimens were dissected to determine the aHH-dTCL distance and the aHH-SPA distance (the distance between the aHH and the superficial palmar arch) at the ulnar and radial limits of the TSZ (the distance between the hook of the hamate or ulnar artery to the median nerve). RESULTS: The aHH-dTCL distance averaged 11-12 mm across the TSZ (maximum, 18.2 mm), whereas the aHH-SPA distance was significantly greater on the radial side of the TSZ compared with the ulnar side (22.6 ± 3.6 mm vs. 14.0 ± 4.0 mm). CONCLUSIONS: The dTCL lies approximately 11-12 mm distal to the aHH across the TSZ, with an upper limit of 18.2 mm. Along with direct sonographic visualization of the dTCL, the aHH can be used with other osseous landmarks to estimate the position of the dTCL during ultrasound-guided carpal tunnel release.

The Physiological Basis of Cervical Facet-Mediated Persistent Pain: Basic Science and Clinical Challenges.

Synopsis Chronic neck pain is a common condition and a primary clinical symptom of whiplash and other spinal injuries. Loading-induced neck injuries produce abnormal kinematics between the vertebrae, with the potential to injure facet joints and the afferent fibers that innervate the specific joint tissues, including the capsular ligament. Mechanoreceptive and nociceptive afferents that innervate the facet have their peripheral terminals in the capsule, cell bodies in the dorsal root ganglia, and terminal processes in the spinal cord. As such, biomechanical loading of these afferents can initiate nociceptive signaling in the peripheral and central nervous systems. Their activation depends on the local mechanical environment of the joint and encodes the neural processes that initiate pain and lead to its persistence. This commentary reviews the complex anatomical, biomechanical, and physiological consequences of facet-mediated whiplash injury and pain. The clinical presentation of facet-mediated pain is complex in its sensory and emotional components. Yet, human studies are limited in their ability to elucidate the physiological mechanisms by which abnormal facet loading leads to pain. Over the past decade, however, in vivo models of cervical facet injury that reproduce clinical pain symptoms have been developed and used to define the complicated and multifaceted electrophysiological, inflammatory, and nociceptive signaling cascades that are involved in the pathophysiology of whiplash facet pain. Integrating the whiplash-like mechanics in vivo and in vitro allows transmission of pathophysiological mechanisms across scales, with the hope of informing clinical management. Yet, despite these advances, many challenges remain. This commentary further describes and highlights such challenges. J Orthop Sports Phys Ther 2017;47(7):450-461. Epub 16 Jun 2017. doi:10.2519/jospt.2017.7255.

Structure and Innervation of the Equine Supraspinous and Interspinous Ligaments.

Pain related to the osseous thoracolumbar spine is common in the equine athlete, with minimal information available regarding soft tissue pathology. The aims of this study were to describe the anatomy of the equine SSL and ISL (supraspinous and interspinous ligaments) in detail and to assess the innervation of the ligaments and their myofascial attachments including the thoracolumbar fascia. Ten equine thoracolumbar spines (T15-L1) were dissected to define structure and anatomy of the SSL, ISL and adjacent myofascial attachments. Morphological evaluation included histology, electron microscopy and immunohistochemistry (S100 and Substance P) of the SSL, ISL, adjacent fascial attachments, connective tissue and musculature. The anatomical study demonstrated that the SSL and ISL tissues merge with the adjacent myofascia. The ISL has a crossing fibre arrangement consisting of four ligamentous layers with adipose tissue axially. A high proportion of single nerve fibres were detected in the SSL (mean = 2.08 fibres/mm2 ) and ISL (mean = 0.75 fibres/mm2 ), with the larger nerves located between the ligamentous and muscular tissue. The oblique crossing arrangement of the fibres of the ISL likely functions to resist distractive and rotational forces, therefore stabilizing the equine thoracolumbar spine. The dense sensory innervation within the SSL and ISL could explain the severe pain experienced by some horses with impinging dorsal spinous processes. Documentation of the nervous supply of the soft tissues associated with the dorsal spinous processes is a key step towards improving our understanding of equine back pain.

Mechanoreceptors of the ligaments and tendons around the knee.

Proprioceptive inputs from the joints and limbs arise from mechanoreceptors in the muscles, ligaments and tendons. The knee joint has a wide range of movements, and proper neuroanatomical organization is critical for knee stability. Four ligaments (the anterior (ACL) and posterior (PCL) cruciate ligaments and the medial (MCL) and lateral (LCL) collateral ligaments) and four tendons (the semitendinosus (STT), gracilis (GT), popliteal (PoT), and patellar (PaT) tendons) from eight fresh frozen cadavers were harvested. Each harvested tissue was divided into its bone insertion side and its tendinous part for immunohistochemical examination using S100 staining. Freeman-Wyke's classification was used to identify the mechanoreceptors. The mechanoreceptors were usually located close to the bone insertion. Free nerve endings followed by Ruffini endings were the most common mechanoreceptors overall. No Pacini corpuscles were observed; free nerve endings and Golgi-like endings were most frequent in the PCL (PCL-PaT: P = 0.0.1, PCL-STT: P = 0.00), and Ruffini endings in the popliteal tendon (PoT-PaT: P = 0.00, Pot-STT: P = 0.00, PoT-LCL: P = 0.00, PoT-GT: P = 0.00, PoT-ACL: P = 0.09). The cruciate ligaments had more mechanoreceptors than the medial structures (MS) or the patellar tendon (CR-Pat: P = 0.000, CR-MS: P = 0.01). The differences in mechanoreceptor distributions between the ligaments and tendons could reflect the different roles of these structures in the dynamic coordination of knee motion. Clin. Anat. 29:789-795, 2016. © 2016 Wiley Periodicals, Inc.

The role of proprioception and neuromuscular stability in carpal instabilities.

Carpal stability has traditionally been defined as dependent on the articular congruity of joint surfaces, the static stability maintained by intact ligaments, and the dynamic stability caused by muscle contractions resulting in a compression of joint surfaces. In the past decade, a fourth factor in carpal stability has been proposed, involving the neuromuscular and proprioceptive control of joints. The proprioception of the wrist originates from afferent signals elicited by sensory end organs (mechanoreceptors) in ligaments and joint capsules that elicit spinal reflexes for immediate joint stability, as well as higher order neuromuscular influx to the cerebellum and sensorimotor cortices for planning and executing joint control. The aim of this review is to provide an understanding of the role of proprioception and neuromuscular control in carpal instabilities by delineating the sensory innervation and the neuromuscular control of the carpus, as well as descriptions of clinical applications of proprioception in carpal instabilities.

What is the function of the anterior coracoscapular ligament? - a morphological study on the newest potential risk factor for suprascapular nerve entrapment.

BACKGROUND: The suprascapular notch (SSN) is the most common site of suprascapular nerve neuropathy, which may be brought on by the presence of a deep, narrow SSN and structures restricting the space for the nerve. The anterior coracoscapular ligament (ACSL) is a fibrous band extending on the anterior side of the suprascapular notch. As it may tighten the osteo-fibrous tunnel for the nerve, it has been proposed as a new anatomical risk factor in its entrapment. However, this structure occurs in up to 60% of patients, many of whom do not demonstrate any nerve injury. The aim of this work is to evaluate the association between the occurrence of the ACSL and SSN morphology. MATERIALS AND METHODS: The suprascapular notch region was dissected in 100 formalin-fixed, cadaveric shoulders. The ACSL (if present) and the SSN were assigned to a classification based on their morphology and diameters. Statistical analysis was performed. RESULTS: The ACSL was present in 52 scapulae (52%) and in all cases, the suprascapular nerve travelled superior to the ACSL. Mechanically relevant types of ACSL were found to occur significantly more often when deeper notches were present (p=0.0018). CONCLUSIONS: The mechanically efficient ACSL is more common in deep and narrow SSNs, which are associated with suprascapular nerve neuropathy. Thus, by supporting the nerve, the ACSL can protect against its injury.

Anatomic variations of pudendal nerve within pelvis and pudendal canal: clinical applications.

OBJECTIVE: The objective of the study was to examine the anatomic variation of the pudendal nerve in the pelvis, on the dorsal surface of the sacrospinous ligament, and in the pudendal canal. STUDY DESIGN: Detailed dissections of the pudendal nerve were performed in unembalmed female cadavers. Pelvic measurements included the distance from the origin of the pudendal nerve to the tip of ischial spine and the nerve width at its origin. The length of the pudendal canal was measured. The inferior rectal nerve was identified in the ischioanal fossa and its course documented. Lastly, the relationship of the pudendal nerve to the dorsal surface of the sacrospinous ligament was examined after transecting the lateral surface of the sacrospinous ligament. Descriptive statistics were used for data analyses and reporting. RESULTS: Thirteen female cadavers (26 hemipelvises) were examined. A single pudendal nerve trunk was identified in 61.5% of hemipelvises. The median distance from the point of the pudendal nerve formation to the ischial spine was 27.5 mm (range, 14.5-37 mm). The width of the pudendal nerve in the pelvis was 4.5 mm (range, 2.5-6.3 mm). The length of the pudendal canal was 40.5 mm (range, 20.5-54.5 mm). The inferior rectal nerve was noted to enter the pudendal canal in 42.3% of hemipelvises; in these cases, the nerve exited the canal at a distance of 32.5 mm (range, 16-45 mm) from the ischial spine. In the remaining specimens, the inferior rectal nerve passed behind the sacrospinous ligament and entered the ischioanal fossa without entering the pudendal canal. In all specimens, the pudendal nerve was fixed by connective tissue to the dorsal surface of the sacrospinous ligament. CONCLUSION: Great variability exists in pudendal nerve anatomy. Fixation of the pudendal nerve to the dorsal surface of the sacrospinous ligament is a consistent finding; thus, pudendal neuralgia attributed to nerve entrapment may be overestimated. The path of the inferior rectal nerve relative to the pudendal canal may have implications in the development of anorectal symptoms. Improved characterization of the pudendal nerve and its branches can help avoid intraoperative complications and enhance existing treatment modalities for pudendal neuropathy.

Pivoting neuromuscular control and proprioception in females and males.

PURPOSE: Noncontact ACL injuries occur most commonly in pivoting sports and are much more frequent in females than in males. However, information on sex differences in proprioceptive acuity under weight-bearing and leg neuromuscular control in pivoting is scarce. The objective of this study was to investigate sex differences in pivoting neuromuscular control during strenuous stepping tasks and proprioceptive acuity under weight-bearing. METHODS: 21 male and 22 female subjects were recruited to evaluate pivoting proprioceptive acuity under weight-bearing, and pivoting neuromuscular control (in terms of leg pivoting instability, stiffness, maximum internal and external pivoting angles, and entropy of time-to-peak EMG in lower limb muscles) during strenuous stepping tasks performed on a novel offaxis elliptical trainer. RESULTS: Compared to males, females had significantly lower proprioceptive acuity under weight-bearing in both internal and external pivoting directions, higher pivoting instability, larger maximum internal pivoting angle, lower leg pivoting stiffness, and higher entropy of time-to-peak EMG in the gastrocnemius muscles during strenuous stepping tasks with internal and external pivoting perturbations. CONCLUSIONS: Results of this study may help us better understand factors contributing to ACL injuries in females and males, develop training strategies to improve pivoting neuromuscular control and proprioceptive acuity, and potentially reduce ACL and lower-limb musculoskeletal injuries.

The foot core system: a new paradigm for understanding intrinsic foot muscle function.

The foot is a complex structure with many articulations and multiple degrees of freedom that play an important role in static posture and dynamic activities. The evolutionary development of the arch of the foot was coincident with the greater demands placed on the foot as humans began to run. The movement and stability of the arch is controlled by intrinsic and extrinsic muscles. However, the intrinsic muscles are largely ignored by clinicians and researchers. As such, these muscles are seldom addressed in rehabilitation programmes. Interventions for foot-related problems are more often directed at externally supporting the foot rather than training these muscles to function as they are designed. In this paper, we propose a novel paradigm for understanding the function of the foot. We begin with an overview of the evolution of the human foot with a focus on the development of the arch. This is followed by a description of the foot intrinsic muscles and their relationship to the extrinsic muscles. We draw the parallels between the small muscles of the trunk region that make up the lumbopelvic core and the intrinsic foot muscles, introducing the concept of the foot core. We then integrate the concept of the foot core into the assessment and treatment of the foot. Finally, we call for an increased awareness of the importance of the foot core stability to normal foot and lower extremity function.

The variable morphology of suprascapular nerve and vessels at suprascapular notch: a proposal for classification and its potential clinical implications.

PURPOSE: The most common place for suprascapular nerve entrapment is the suprascapular notch. The aim of the study was to determine the morphological variation of the location of the suprascapular nerve, artery and vein, and measure the reduction in size of the suprascapular opening in each type of the passage. METHODS: A total of 106 human formalin-fixed cadaveric shoulders were included in the study. After dissection of the suprascapular region, the topography of the suprascapular nerve, artery and vein was evaluated. Additionally, the area of the suprascapular opening was measured using professional image analysis software. RESULTS: Four arrangements of the suprascapular vein, artery and nerve were distinguished with regard to the superior transverse scapular ligament: type I (61.3 %) (suprascapular artery was running above ligament, while suprascapular vein and nerve below it), type II (17 %) (both vessels pass above ligament, while nerve passes under it), type III (12.3 %) (suprascapular vessels and nerve lie under ligament) and type IV (9.4 %), which comprises the other variants of these structures. Statistically significant differences regarding the suprascapular opening were observed between the specimens with types II and III. Anterior coracoscapular ligaments were present in 55 from 106 shoulders. CONCLUSION: The morphological variations described in this study are necessary to better understand the possible anatomical conditions which may promote suprascapular nerve entrapment (especially type III). They may be useful during open and endoscopic procedures at the suprascapular notch to prevent such complications as unexpected bleeding.

Supracondylar process syndrome: case report and literature review.

The supracondylar process is a congenital bone projection on the distal anteromedial humerus often associated with a ligament of Struthers, a fibrous connection between the process and medial epicondyle. It is largely asymptomatic and only on rare occasions presents with neurovascular compression resulting in a supracondylar process syndrome. This case report describes a 28-year-old woman with supracondylar process syndrome, and our management. The topic is further explored with a literature review of 43 reported cases. Analysis of the case reports indicates that isolated median nerve injuries are the most common. Other presentations such as fractures, vascular compromise, and ulnar nerve involvement are less frequent.