Suture augmentation of acromioclavicular and coracoclavicular ligament reconstruction for acute acromioclavicular dislocation

The objective of this report was to introduce a new suture augmentation of coracoclavicular (CC) and acromioclavicular ligament reconstruction for acute Rockwood grade III to V acromioclavicular dislocations.From January 2015 to January 2019, 43 patients with Rockwood III to VI acute acromioclavicular dislocations were retrospectively reviewed. For comparison, another series of 28 patients treated with double Endobutton technique from January 2011 to December 2014 were reviewed. A P < .05 was considered statistical significance.The mean follow-up period of the 2 series were 39.69 ± 7.42 months (range, 24-54 months) and 37.86 ± 8.23 months (range, 26-48 months) (P > .05), respectively. There were significant differences regarding CC space (11.62 ± 2.54 mm vs 16.78 ± 5.53 mm; P < .05), CC reduction loss (5.56 ± 4.73 mm vs 26.25 ± 4.42 mm; P < .05), and acromioclavicular space (6.89 ± 1.87 mm vs 7.95 ± 2.37 mm; P < .05). There were significant differences regarding the disabilities of the arm, shoulder, and hand questionnaire (3.3 ± 2.8 vs 5.32 ± 4.37; P < .05) and University of California-Los Angeles shoulder rating scale (31.19 ± 2.48 vs 29.24 ± 2.48; P < .05). The excellent to good percentages were 100% (n = 32) and 85% (n = 23), respectively.In conclusion, the suture augmentation of acromioclavicular and CC ligament reconstruction is a reliable technique for acute acromioclavicular dislocation with minimal complications.Type of study/level of evidence: Therapeutic IIa.

Mechanics of Uterosacral Ligaments: Current Knowledge, Existing Gaps, and Future Directions

The uterosacral ligaments (USLs) are important anatomical structures that support the uterus and apical vagina within the pelvis. As these structures are over-stretched, become weak, and exhibit laxity, pelvic floor disorders such as pelvic organ prolapse occur. Although several surgical procedures to treat pelvic floor disorders are directed toward the USLs, there is still a lot that is unknown about their function. This manuscript presents a review of the current knowledge on the mechanical properties of the USLs. The anatomy, microstructure, and clinical significance of the USLs are first reviewed. Then, the results of published experimental studies on the in vivo and ex vivo, uniaxial and biaxial tensile tests are compiled. Based on the existing findings, research gaps are identified and future research directions are discussed. The purpose of this exhaustive review is to help new researchers navigate scientific literature on the mechanical properties of the USLs. The use of these structures remains very popular in reconstructive surgeries that restore and augment the support of pelvic organs, especially as synthetic surgical mesh implants continue to be highly controversial.

Volar and Dorsal Blood Supply to the Lunate: A Cadaveric Study

Although various studies have proposed vascular and mechanical factors, the etiology of Kienböck disease is unknown. Kienböck theorized that lunatomalacia resulted from traumatic disruption of blood supply and bony nutrition to the lunate. Extraosseous supply to the lunate, as far as volar or dorsal vessels are concerned, is still controversial. This study evaluated the extraosseous nutrient foramina from the dorsal and volar aspects of lunate specimens. A total of 913 specimens from the Hamann-Todd Osteological Collection in Cleveland, Ohio, were examined. The nutrient artery foramina on left and right lunate specimens were examined from dorsal and volar aspects. The number of nutrient artery foramen was tabulated. Age, sex, and race data were collected. Specimens were divided into groups according to the number of nutrient artery foramina, and the dorsal and volar foramina were compared. The average number of foramina on the dorsal aspect of the lunate (1.71) was greater than the volar aspect (1.64), except in specimens younger than 35 years. A greater number of specimens had 3 or more foramina on the dorsal side compared with the volar aspect. Based on this study, there was significant contribution of dorsal arterial vessels to the blood supply of lunate specimens older than 35 years, which contrasts with findings in earlier studies. The disruption of dorsal intercarpal and radiocarpal ligaments leading to the disruption of the dorsal arterial arches may contribute to vascular insufficiency of the lunate and should be evaluated further in the etiopathogenesis of Kienböck disease. [Orthopedics. 2021;44(2):e243-e247.].

Comparison of Biaxial Biomechanical Properties of Post-menopausal Human Prolapsed and Non-prolapsed Uterosacral Ligament

Uterosacral ligaments (USLs) provide structural support to the female pelvic floor, and a loss of USL structural integrity or biomechanical function may induce pelvic organ prolapse (POP). Alterations in extracellular matrix composition and organization dictate USL mechanical function. Changes in USL microstructure and corresponding mechanical properties, however, are not fully understood, nor is it understood how microstructure and mechanics change with onset and progression of POP. This is due, in part, as USL properties are primarily characterized along a single direction (uniaxial test), whereas the USL is loaded in multiple directions simultaneously within the body. Biaxial testing permits the acquisition of biomechanical data from two axes simultaneously, and thus simulates a more physiologic assessment compared to the traditional uniaxial testing. Therefore, the objective of this study was to quantify the biaxial biomechanical properties and histological composition of the USL in post-menopausal women with and without POP at various stages. Potential correlations between tissue microstructural composition and mechanical function were also examined. Tangential modulus was lower and peak stretch higher in POP III/IV compared to non-POP and POP I/II in the main in vivo loading direction; however, no significant differences in mechanical properties were observed in the perpendicular loading direction. Collagen content positively correlated to tangential modulus in the main in vivo loading direction (r = 0.5, p = 0.02) and negatively correlated with the peak stretch in both the main in vivo (r = -0.5, p = 0.02) and perpendicular loading directions (r = -0.3, p = 0.05). However, no statistically significant differences in USL composition were observed, which may be due to the small sample size and high variability of small sections of human tissues. These results provide first step towards understanding what microstructural and mechanical changes may occur in the USL with POP onset and progression. Such information may provide important future insights into the development of new surgical reconstruction techniques and graft materials for POP treatment.

Could an isolated human body lower limb model predict leg biomechanical response of Chinese pedestrians in vehicle collisions?

PURPOSE

The purpose of the current study was to investigate whether an isolated human body lower limb FE model could predict leg kinematics and biomechanical response of a full body Chinese pedestrian model in vehicle collisions.

METHODS

A human body lower limb FE model representing midsize Chinese adult male anthropometry was employed with different upper body weight attachments being evaluated by comparing the predictions to those of a full body pedestrian model in vehicle-to-pedestrian collisions considering different front-end shapes.

RESULTS

The results indicate that upper body mass has a significant influence on pedestrian lower limb injury risk, the effect varies from vehicle front-end shape and is more remarkable to the femur and knee ligaments than to the tibia. In particular, the upper body mass can generally increase femur and knee ligaments injury risk, but has no obvious effect on the injury risk of tibia. The results also show that a higher attached buttock mass is needed for isolated pedestrian lower limb model for impacts with vehicles of higher bonnet leading edge.

CONCLUSIONS

The findings of this study may suggest that it is necessary to consider vehicle shape variation in assessment of vehicle pedestrian protection performance and leg-form impactors with adaptive upper body mass should be used for vehicles with different front-end shapes, and the use of regional leg-form impactor modeling the local anthropometry to evaluate the actual lower limb injury of pedestrians in different countries and regions.

What is the reason of the high fibular head in the Discoid Lateral Meniscus?

The purpose of this study was to assess the factors associated with high fibular head in symptomatic discoid lateral meniscus (DLM). Eighty-seven patients with complete DLM (discoid group) and 80 normal subjects (control group) were included prospectively. Plain X-rays and MRI were analyzed for level and angle of the fibular head and thickness and type of Wrisberg ligament. Multivariate regression analysis was performed to find the factors associated with levels of the fibular head and DLM. The angle of the fibular head was the only factor associated with level of the fibula in the discoid group (odds ratio : 3.0, p=0.007). The 13.6mm cut off value for fibular level had 70.5% sensitivity and 77.0% specificity for diagnosis of DLM. A high fibular head was associated with larger angle and type of fibular head. Level of evidence : Level II.

Repeated High Rate Facet Capsular Stretch at Strains That are Below the Pain Threshold Induces Pain and Spinal Inflammation With Decreased Ligament Strength in the Rat

Repeated loading of ligamentous tissues during repetitive occupational and physical tasks even within physiological ranges of motion has been implicated in the development of pain and joint instability. The pathophysiological mechanisms of pain after repetitive joint loading are not understood. Within the cervical spine, excessive stretch of the facet joint and its capsular ligament has been implicated in the development of pain. Although a single facet joint distraction (FJD) at magnitudes simulating physiologic strains is insufficient to induce pain, it is unknown whether repeated stretching of the facet joint and ligament may produce pain. This study evaluated if repeated loading of the facet at physiologic nonpainful strains alters the capsular ligament's mechanical response and induces pain. Male rats underwent either two subthreshold facet joint distractions (STFJDs) or sham surgeries each separated by 2 days. Pain was measured before the procedure and for 7 days; capsular mechanics were measured during each distraction and under tension at tissue failure. Spinal glial activation was also assessed to probe potential pathophysiologic mechanisms responsible for pain. Capsular displacement significantly increased (p = 0.019) and capsular stiffness decreased (p = 0.008) during the second distraction compared to the first. Pain was also induced after the second distraction and was sustained at day 7 (p < 0.048). Repeated loading weakened the capsular ligament with lower vertebral displacement (p = 0.041) and peak force (p = 0.014) at tissue rupture. Spinal glial activation was also induced after repeated loading. Together, these mechanical, physiological, and neurological findings demonstrate that repeated loading of the facet joint even within physiologic ranges of motion can be sufficient to induce pain, spinal inflammation, and alter capsular mechanics similar to a more injurious loading exposure.

Medial knee loading is altered in subjects with early osteoarthritis during gait but not during step-up-and-over task

This study evaluates knee joint loading during gait and step-up-and-over tasks in control subjects, subjects with early knee OA and those with established knee OA. Thirty-seven subjects with varying degrees of medial compartment knee OA severity (eighteen with early OA and sixteen with established OA), and nineteen healthy controls performed gait and step-up-and-over tasks. Knee joint moments, contact forces (KCF), the magnitude of contact pressures and center of pressure (CoP) location were analyzed for the three groups for both activities using a multi-body knee model with articular cartilage contact, 14 ligaments, and six degrees of freedom tibiofemoral and patellofemoral joints. During gait, the first peak of the medial KCF was significantly higher for patients with early knee OA (p = 0.048) and established knee OA (p = 0.001) compared to control subjects. Furthermore, the medial contact pressure magnitudes and CoP location were significantly different in both groups of patients compared to controls. Knee rotation moments (KRMs) and external rotation angles were significantly higher during early stance in both patient groups (p < 0.0001) compared to controls. During step-up-and-over, there was a high variability between the participants and no significant differences in KCF were observed between the groups. Knee joint loading and kinematics were found to be altered in patients with early knee OA only during gait. This is an indication that an excessive medial KCF and altered loading location, observed in these patients, is a contributor to early progression of knee OA.

Small incision releasing of transverse carpal ligament in diagnosis and treatment of mild carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a medical condition due to compression of the median nerve as it travels through the wrist at the carpal tunnel. Few studies have been carried out to examine the effectiveness of mini-open technique for carpal tunnel release using minor wrist skin crease incision in patients with mild CTS. Therefore, the present study was designed to improve the neurophysiological parameters for the diagnosis of mild CTS, and to examine the effectiveness of small incision surgery for the clinical treatment of mild CTS. To this end, we applied the electrophysiological diagnosis of difference between median and ulnar palmar latencies (PMPU) and the difference of median and ulnar latencies from D4 stimulation (D4MD4U) in 80 patients with mild CTS, whom were diagnosed by hand surgeon at the First Hospital of Jilin University. Those patients showed normal in median nerve electrophysiological examination, and received minor wrist skin crease incision surgery. All patients were followed up and received electromyography (EMG) examination. We showed that D4MD4U and PMPU methods are sensitive diagnosis methods for mild CTS, and mini-open wrist crease incision is beneficial for the treatment of mild CTS in clinical settings.

Effects of Cementing on Ligament Balance During Total Knee Arthroplasty

Complications related to joint imbalance may contribute to some of the most predominant modes of failure in total knee arthroplasty (TKA). These complications include instability, aseptic loosening, asymmetric component wear, and idiopathic pain. Fixation may represent a step that introduces unchecked variability into the procedure and may contribute to the incidence of joint imbalance-related complications. The ability to quantify in vivo loading in the medial and lateral compartments would allow for the ability to confirm balance after fixation and prior to wound closure. This retrospective study sought to capture any variability and imbalance associated with cementing technique. A total of 93 patients underwent sensor-assisted TKA. All patients were confirmed to have quantifiably balanced joints prior to cementation. After cementing and final component placement, the sensor was reinserted into the joint to capture any cementation-induced changes in loading. Imbalance was observed in 44% of patients after cementation. There was no difference in the proportion of imbalance due to surgeon experience (P=.456), cement type (P=.429), or knee system (P=.792). A majority of knees exhibited loading increase in the medial compartment. It was concluded that cementation technique contributes to a significant amount of balance-related variability at the fixation stage of the procedure. The use of the sensor in this study allowed for the correction of all instances of imbalance prior to closure. More objective methods of balance verification may be important for ensuring optimal surgical outcomes. [Orthopedics. 2017; 40(3):e455-e459.].

Recent Advances in Understanding Pelvic-Floor Tissue of Women With and Without Pelvic Organ Prolapse: Considerations for Physical Therapists

Pelvic organ prolapse is a fairly common condition that imposes significant symptoms, diminished quality of life, social burden, financial expense, and surgical risk on women. As evidence supporting the benefit of pelvic-floor muscle training in nonsurgical management of pelvic organ prolapse grows, physical therapists are becoming a provider of choice interacting with women affected by pelvic organ prolapse. This perspective article will review recent research on tissue characteristics of 3 key components of pelvic organ support: skeletal muscle, ligament, and vaginal wall. This information will be summarized as implications for physical therapists. An improved understanding of pelvic-floor tissue in women with and without pelvic organ prolapse will provide a more comprehensive appreciation of the interaction of multiple systems in the disorder.

Platelet Rich Plasma in Musculoskeletal Pathology: A Necessary Rescue or a Lost Cause?

BACKGROUND

Platelet rich plasma (PRP) has been used for decades to facilitate surgical tissue repair; therefore, the current trend of percutaneously injecting PRP to theoretically enhance tissue regeneration and repair is a logical progression. Applications include treatment of osteoarthritis, tendinopathy, chondropathy, acute and chronic soft tissue injuries, muscle or ligament tear, as well as enhancement of healing after bone or tissue reconstruction. However, there is limited evidence to support the use of PRP in the abovementioned conditions. Variations in the preparation of PRP and its application in various conditions influence its effect on various orthopedic conditions.

OBJECTIVE

To provide a basic overview of the current use of PRP in treating musculoskeletal conditions.

METHODS

Studies relevant to PRP were extracted from the PubMed and Medline database within the dates ranging from 1990 through 2015. These studies included in vitro as well as in-vivo animal experiments and careful analysis of the study population, type of intervention, and outcomes was made.

RESULTS

PRP has been noted to be a beneficial solution for tissue healing based on limited current literature. However a variety of factors such as method of preparation, composition, medical condition of the patient, anatomic location of the lesion, and tissue type can alter outcome.

CONCLUSION

The effectiveness and potential adverse effects of this treatment require high quality studies prior to widespread clinical application.Key words: Growth factors, platelet rich plasma, regeneration, regenerative healing, tissue repair, stem cells, mesenchymal stem cells, tissue engineering.

Office-Based Laryngoscopic Observations of Recurrent Laryngeal Nerve Paresis and Paralysis

Objectives:

To evaluate the endoscopic criteria of recurrent laryngeal nerve disorders, we performed a retrospective evaluation of videolaryngoscopic recordings from 50 patients with recurrent laryngeal nerve disorders.

Methods:

The videolaryngoscopic examination was performed with rigid and flexible endoscopes. The range of motion of three laryngeal structures was assessed: the vocal ligament, the vocal process, and the arytenoid “hump” (mainly the corniculate region).

Results:

Comparison of movement of these three structures revealed discrepancies. In 16 of 45 patients (36%) rigid endoscopy showed movements of the arytenoid hump associated with absence of any mobility of the vocal process and vocal ligament. In 5 patients the extent of movement of the vocal process and vocal ligament was less than that of the arytenoid hump. Only in 24 of 45 cases were the ratings for the vocal process, vocal ligament, and arytenoid hump identical. The findings of fiberscopy were comparable.

Conclusions:

In assessing recurrent laryngeal nerve disorders via laryngoscopy, sole judgment of the arytenoid hump movement can mislead. Our interpretation suggests that visible movement of the mucosa covering the arytenoid and accessory cartilages is not always paralleled by movement of the arytenoid cartilage itself. It was shown that the best criterion to rely on in endoscopy is movement of the vocal process or the vocal ligament.

[Surgical treatment of multiple ligament injuries of knee joints]

OBJECTIVE

To study operative effects for the treatment of multiple ligament injuries of knee joints.

METHODS

From 2008 to 2013, 26 patients (17 males and 9 females) with multiple ligament injuries of knee joints were treated surgically. The average age was 40.7 years old, ranging from 29 to 55 years old. All the patients were treated with arthroscopic reconstruction of cruiate ligament with autogenous or allogeneic hamstrings and tendon, and at the same time received repair of medial collateral ligament and lateral collateral ligament, as well as the treatment of exterior and interior complex injuries. Nine patients received second stage operation after the initial operation for mistake or missed diagnosis, and other patients were treated at the first stage. The Lysholm scoring system was used to evaluate function and stability of knee joints before and after operation.

RESULTS

All the patients were followed up for an average duration of 1.6 years (ranged, 0.8 to 3.2 years). The mean awaiting time for operation was 1.2 months. The Lysholm score was improved from preoperative 42.5 +/- 4.5 (ranged, 33 to 48) to the latest follow-up 78.1 +/- 3.9 (ranged, 57 to 95). The function of knee joint was improved obviously in the arthroscopic reconstruction patients, with joint range of motion exceeding 900 and with Varus & Valgus tests near to normal. All the patients had negative findings in the Lachman test at 70 degrees of flexion.

CONCLUSION

Arthroscopic reconstruction should be the first choice in treating multiple ligament injuries of knee joints. If the anterior and posterior cruciate ligament injuries can't be treated simultaneously, the posterior cruciate ligament injuries should be treated preferentially at the first stage and the anterior cruciate ligament injuries should be treated at the second stage. The diagnosis of posterior cruciate ligament is easy to be missed.

Adaptation of the Transverse Carpal Ligament Associated with Repetitive Hand Use in Pianists

The transverse carpal ligament (TCL) plays a critical role in carpal tunnel biomechanics through interactions with its surrounding tissues. The purpose of this study was to investigate the in vivo adaptations of the TCL’s mechanical properties in response to repetitive hand use in pianists using acoustic radiation force impulse (ARFI) imaging. It was hypothesized that pianists, in comparison to non-pianists, would have a stiffer TCL as indicated by an increased acoustic shear wave velocity (SWV). ARFI imagining was performed for 10 female pianists and 10 female non-pianists. The median SWV values of the TCL were determined for the entire TCL, as well as for its radial and ulnar portions, rTCL and uTCL, respectively. The TCL SWV was significantly increased in pianists relative to non-pianists (p < 0.05). Additionally, the increased SWV was location dependent for both pianist and non-pianist groups (p < 0.05), with the rTCL having a significantly greater SWV than the uTCL. Between groups, the rTCL SWV of pianists was 22.2% greater than that of the non-pianists (p < 0.001). This localized increase of TCL SWV, i.e. stiffening, may be primarily attributable to focal biomechanical interactions that occur at the radial TCL aspect where the thenar muscles are anchored. Progressive stiffening of the TCL may become constraining to the carpal tunnel, leading to median nerve compression in the tunnel. TCL maladaptation helps explain why populations who repeatedly use their hands are at an increased risk of developing musculoskeletal pathologies, e.g. carpal tunnel syndrome.

Application of a three-dimensional computational wrist model to proximal row carpectomy

A three-dimensional (3D) computational model of the wrist examined the biomechanical effects of the proximal row carpectomy (PRC), a surgical treatment of certain wrist degenerative conditions but with functional consequences. Model simulations, replicating the 3D bony anatomy, soft tissue restraints, muscle loading, and applied perturbations, demonstrated quantitatively accurate responses for the decreased motions subsequent to the surgical procedure. It also yielded some knowledge of alterations in radiocarpal contact force which likely increase contact pressure as well as additional insight into the importance of the triangular fibrocartilage complex and retinacular/capsular structures for stabilizing the deficient wrist. As better understanding of the wrist joint is achieved, this model could serve as a useful clinical tool.

Characterization of the discrepancies between four-dimensional phase-contrast magnetic resonance imaging and in-silico simulations of cerebrospinal fluid dynamics

The purpose of the present study was to compare subject-specific magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) simulations with time-resolved three-directional (3D) velocity-encoded phase-contrast MRI (4D PCMRI) measurements of the cerebrospinal fluid (CSF) velocity field in the cervical spinal subarachnoid space (SSS). Three-dimensional models of the cervical SSS were constructed based on MRI image segmentation and anatomical measurements for a healthy subject and patient with Chiari I malformation. CFD was used to simulate the CSF motion and compared to the 4D PCMRI measurements. Four-dimensional PCMRI measurements had much greater CSF velocities compared to CFD simulations (1.4 to 5.6× greater). Four-dimensional PCMRI and CFD both showed anterior and anterolateral dominance of CSF velocities, although this flow feature was more pronounced in 4D PCMRI measurements compared to CFD. CSF flow jets were present near the nerve rootlets and denticulate ligaments (NRDL) in the CFD simulation. Flow jets were visible in the 4D PCMRI measurements, although they were not clearly attributable to nerve rootlets. Inclusion of spinal cord NRDL in the cervical SSS does not fully explain the differences between velocities obtained from 4D PCMRI measurements and CFD simulations.

In vivo properties of uterine suspensory tissue in pelvic organ prolapse

The uterine suspensory tissue (UST), which includes the cardinal (CL) and uterosacral ligaments (USL), plays an important role in resisting pelvic organ prolapse (POP). We describe a technique for quantifying the in vivo time-dependent force-displacement behavior of the UST, demonstrate its feasibility, compare data from POP patients to normal subjects previously reported, and use the results to identify the properties of the CL and USL via biomechanical modeling. Fourteen women with prolapse, without prior surgeries, who were scheduled for surgery, were selected from an ongoing study on POP. We developed a computer-controlled linear servo actuator, which applied a continuous force and simultaneously recorded cervical displacement. Immediately prior to surgery, the apparatus was used to apply three "ramp and hold" trials. After a 1.1 N preload was applied to remove slack in the UST, a ramp rate of 4 mm/s was used up to a maximum force of 17.8 N. Each trial was analyzed and compared with the tissue stiffness and energy absorbed during the ramp phase and normalized final force during the hold phase. A simplified four-cable model was used to analyze the material behavior of each ligament. The mean ± SD stiffnesses of the UST were 0.49 ± 0.13, 0.61 ± 0.22, and 0.59 ± 0.2 N/mm from trial 1 to 3, with the latter two values differing significantly from the first. The energy absorbed significantly decreased from trial 1 (0.27 ± 0.07) to 2 (0.23 ± 0.08) and 3 (0.22 ± 0.08 J) but not from trial 2 to 3. The normalized final relaxation force increased significantly with trial 1. Modeling results for trial 1 showed that the stiffnesses of CL and USL were 0.20 ± 0.06 and 0.12 ± 0.04 N/mm, respectively. Under the maximum load applied in this study, the strain in the CL and USL approached about 100%. In the relaxation phase, the peak force decreased by 44 ± 4% after 60 s. A servo actuator apparatus and intraoperative testing strategy proved successful in obtaining in vivo time-dependent material properties data in representative sample of POP. The UST exhibited visco-hyperelastic behavior. Unlike a knee ligament, the length of UST could stretch to twice their initial length under the maximum force applied in this study.

The impact of spinal cord nerve roots and denticulate ligaments on cerebrospinal fluid dynamics in the cervical spine

Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and denticulate ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.

[Cervical spine instability in the surgical patient]

Many congenital and acquired diseases, including trauma, may result in cervical spine instability. Given that airway management is closely related to the movement of the cervical spine, it is important that the anesthesiologist has detailed knowledge of the anatomy, the mechanisms of cervical spine instability, and of the effects that the different airway maneuvers have on the cervical spine. We first review the normal anatomy and biomechanics of the cervical spine in the context of airway management and the concept of cervical spine instability. In the second part, we review the protocols for the management of cervical spine instability in trauma victims and some of the airway management options for these patients.

Structure, physiology, and biochemistry of collagens

Tendons and ligaments are connective tissues that guide motion, share loads, and transmit forces in a manner that is unique to each as well as the anatomical site and biomechanical stresses to which they are subjected. Collagens are the major molecular components of both tendons and ligaments. The hierarchical structure of tendon and its functional properties are determined by the collagens present, as well as their supramolecular organization. There are 28 different types of collagen that assemble into a variety of supramolecular structures. The assembly of specific supramolecular structures is dependent on the interaction with other matrix molecules as well as the cellular elements. Multiple suprastructural assemblies are integrated to form the functional tendon/ligament. This chapter begins with a discussion of collagen molecules. This is followed by a definition of the supramolecular structures assembled by different collagen types. The general principles involved in the assembly of collagen-containing suprastructures are presented focusing on the regulation of tendon collagen fibrillogenesis. Finally, site-specific differences are discussed. While generalizations can be made, differences exist between different tendons as well as between tendons and ligaments. Compositional differences will impact structure that in turn will determine functional differences. Elucidation of the unique physiology and pathophysiology of different tendons and ligaments will require an appreciation of the role compositional differences have on collagen suprastructural assembly, tissue organization, and function.

A novel technique to measure in vivo uterine suspensory ligament stiffness

OBJECTIVE

The purpose of this study was to describe a new computer-controlled research apparatus for measuring in vivo uterine ligament force-displacement behavior and stiffness and to present pilot data for women with and without prolapse.

STUDY DESIGN

Seventeen women with varying uterine support underwent testing in the operating room (OR) after anesthetic induction. A tripod-mounted computer-controlled linear servoactuator was used to quantify force-displacement behavior of the cervix and supporting ligaments. The servoactuator applied a caudally directed force to a tenaculum at 4 mm/sec velocity until the traction force reached 17.8 N (4 lbs). Cervix location on Pelvic Organ Prolapse Quantification system (POP-Q) in the clinic, in the OR, at rest, and with minimal force (<1.1 N); maximum force (17.8 N) was recorded. Ligament "stiffness" between minimum and maximum force was calculated.

RESULTS

The mean ± SD subject age was 54.5 ± 12.7 years; parity was 2.9 ± 1.1; body mass index was 29.0 ± 4.3 kg/m(2), and POP-Q point C was -3.1 ± 3.9 cm. POP-Q point C was correlated most strongly with cervix location at maximum force (r = +0.68; P = .003) and at rest (r = +0.62; P = .009). Associations between cervix location at minimum force (r = +0.46; P = .059) and ligament stiffness (r = -0.44; P = .079) were not statistically significant. Cervix location in the OR with minimal traction lay below the lowest point found on POP-Q for 13 women.

CONCLUSION

POP-Q point C was correlated strongly with cervix location at rest and at maximum traction force; however, only 19% of the variation in POP-Q point C location was explained by ligament stiffness. The cervix location in the OR at minimal traction lay below POP-Q point C value in three-fourths of the women.

Biomechanical evaluation of anatomical double-bundle coracoclavicular ligament reconstruction secured with knot fixation versus screw fixation

Methods to reconstruct the coracoclavicular ligaments anatomically have been described. No clear advantage of 1 technique has been elucidated. The authors' hypothesis was that the biomechanical properties of a modified knot fixation technique would be similar to the anatomical double-bundle technique. Sixteen matched cadaveric shoulders were used for this study, and 1 additional shoulder was used in the knot fixation group only. Shoulders were randomly assigned to the anatomical double-bundle coracoclavicular ligament reconstruction technique (n=8) or a knot fixation technique (n=9). The intact coracoclavicular ligaments were tested to failure with superior displacement at a rate of 2 mm/s. Reconstruction was performed using a semitendinosus tendon allograft, and load to failure was repeated for each construct. Ultimate failure load, stiffness, and failure mode were compared using a paired t test (P<.05). No significant difference existed in load to failure between native and reconstructed ligaments or between reconstruction techniques. Stiffness decreased significantly after reconstruction in the double-bundle group (from 32.5 to 22.5 N/mm; P=.035) and in the modified knot fixation group (from 35.5 to 21.9 N/mm; P=.043). No significant difference existed in stiffness between the 2 reconstruction groups. A significant difference (P=.003) existed between failure modes between the 2 reconstruction techniques. Although less stiff than the native ligament, either technique used to reconstruct the coracoclavicular ligament can be performed to yield a load to failure similar to the intact ligament. The majority of failures in the double-bundle group were by means of the graft slipping at the screw-tendon interface at 1 of the clavicular drill holes. The modified knot fixation technique failed the majority of the time by graft elongation.

Influence of kinematic analysis methods on detecting ankle and subtalar joint instability

Patients with subtalar joint instability may be misdiagnosed with ankle instability, which may lead to chronic instability at the subtalar joint. Therefore, it is important to understand the difference in kinematics after ligament sectioning and differentiate the changes in kinematics between ankle and subtalar instability. Three methods may be used to determine the joint kinematics; the Euler angles, the Joint Coordinate System (JCS) and the helical axis (HA). The purpose of this study was to investigate the influence of using either method to detect subtalar and ankle joints instability. 3D kinematics at the ankle and subtalar joint were analyzed on 8 cadaveric specimens while the foot was intact and after sequentially sectioning the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), the cervical ligament and the interosseous talocalcaneal ligament (ITCL). Comparison in kinematics calculated from sensor and anatomical landmarks was conducted as well as the influence of Euler angles and JCS rotation sequence (between ISB recommendation and previous research) on the subtalar joint. All data showed a significant increase in inversion when the ITCL was sectioned. There were differences in the data calculated using sensors coordinate systems vs. anatomic coordinate systems. Anatomic coordinate systems were recommended for these calculations. The Euler angle and JCS gave similar results. Differences in Euler angles and JCS sequence lead to the same conclusion in detecting instability at the ankle and subtalar joint. As expected, the HA detected instability in plantarflexion at the ankle joint and in inversion at the subtalar joint.

Treatment for carpal tunnel syndrome by coronal Z-type lengthening of the transverse carpal ligament

OBJECTIVE

To compare the effects of coronal Z-type lengthening of transverse carpal ligament with conventional open approach for carpal tunnel syndrome.

METHODS

A double-blinded study was conducted from January 2005 to August 2008 on 68 patients with a mean age of 41 years (range 27-55 years) diagnosed as severe carpal tunnel syndrome. They were randomized into two groups(A and B). Patients in group A underwent coronal Z-type lengthening of transverse carpal ligament; and patients in group B had conventional open approach surgery. Postoperative evaluation was scheduled at 1, 3, 6 and 12 months after the surgery and incidence rate of bowstring of the flexor tendons, improvement of grip strength and ADL activities of daily living) score were recorded.

RESULTS

Fifty-eight patients had been followed up successfully, 30 and 28 for group A and B respectively. The Scar Tissue Formation of the flexor tendons in group B was observed more than that in group A at 6 and 12 month after operation. Improvement of grip strength were observed in two groups, which was statistically different between 6 and 12 months after operation and no significant difference was seen between 1 and 3 months after operation. According to ADL, the satisfaction rates documented on form for patients were statistically different in the two groups at 6 and 12 months after operation and no difference was noted at 1 and 3 months after operation.

CONCLUSION

Excellent improvement of function and satisfaction were achieved by Coronal Z-type reconstruction of the flexor retinaculum for severe carpal tunnel syndrome. Our method offers a more effective alternative method for conventional carpal tunnel open decompression surgery.

Crystallization study and comparative in vitro-in vivo hydrolysis of PLA reinforcement ligament

In the present work, the crystallization behavior and in vitro-in vivo hydrolysis rates of PLA absorbable reinforcement ligaments used in orthopaedics for the repair and reinforcement of articulation instabilities were studied. Tensile strength tests showed that this reinforcement ligament has similar mechanical properties to Fascia Latta, which is an allograft sourced from the ilio-tibial band of the human body. The PLA reinforcement ligament is a semicrystalline material with a glass transition temperature around 61 °C and a melting point of ~178 °C. Dynamic crystallization revealed that, although the crystallization rates of the material are slow, they are faster than the often-reported PLA crystallization rates. Mass loss and molecular weight reduction measurements showed that in vitro hydrolysis at 50 °C initially takes place at a slow rate, which gets progressively higher after 30-40 days. As found from SEM micrographs, deterioration of the PLA fibers begins during this time. Furthermore, as found from in vivo hydrolysis in the human body, the PLA reinforcement ligament is fully biocompatible and after 6 months of implantation is completely covered with flesh. However, the observed hydrolysis rate from in vivo studies was slow due to high molecular weight and degree of crystallinity.

[The value of MRI in diagnosis of ligament injuries of knee joint]

OBJECTIVE

To study the performance of MRI and its diagnostic value for ligament injuries of knee joint.

METHODS

Form June 2008 to February 2010, the MRI of 74 patients with ligament injuries of knee joint were retrospectively analyzed. There were 47 males and 27 females in the group, which course was from 2 h to 10 d, with an average age of 37.3 years (ranged from 12 to 76). The clinical symptom included knee swelling, pain, joint instability, extension-flexion movement disorder. The physical examination showed valgus test or drawer test positive, and tenderness of medial knee positive.

RESULTS

There were ligament injuies in 74 cases, among them, 19 cases were anterior cruciate ligament (25.7%),18 were posterior cruciate ligament (24.3%), 13 were lateral collateral ligament (17.6%), 24 were medial collateral (32.4%), the ligament of 12 cases were completely broken (included 8 cases cruciate ligament and 4 cases collateral ligament presented as discontinued signals of the ligament, and swelling and thickening of the ligament with medium signal in PDWI and high signal intensity in T2WI and in SPIR). The MRI of 62 patients with partial longitudinal tearing ligaments showed continuity, swelling and thickening of the ligaments with medium signal in PDWI and high signal intensity in T2WI and in SPIR. Forty-four cases were examined with surgery and arthroscopy, 41 ligaments were accorded with MRI, diagnosis rate of MRI was 95%.

CONCLUSION

MRI can accurately diagnose the ligament injuries of knee joint,which is an ideal technique in the diagnosis of ligament injuries of knee joint, and should be used as a routine examining method.

[Clinical significance of nuchal ligament calcification and the discussion on biomechanics]

OBJECTIVE

To improve the cognition about X-ray characteristics of nuchal ligament calcification, and discuss biomechanical properties.

METHODS

From September 2008 to August 2009, the X-rays of 163 cases showed nuchal ligament calcification, which datas were analyzed. There were 91 males and 72 females, the age from 38 to 68 with an average of 53.6 years. And the number of calcification segment, related vertebral level, and vertebral hyperosteogeny, intervertebral space or intervertebral foramen stenosis, anterior or posterior longitudinal ligament calcification, cervical instability in the relative segment were observed.

RESULTS

One hundred forty-one patients occurred degeneration in the relative segment. The characteristics of X-ray: the multiple nuchal ligament calcification existed single segment and the C5,6 and C4,5 were readily occurred, which multiple related vertebral sclerotin, intervertebral space or intervertebral foramen, anterior or posterior longitudinal ligament occurred pathological changes, moreover, it was main segment of pathological changes. The X-rays of 93 cases showed vertebral hyperosteogeny 72 intervertebral space or intervertebral foramen stenosis, 49 anterior or posterior longitudinal ligament calcification, 66 cervical instability in the relative segment. The percentage was respectively 65.96%, 51.06%, 34.75%, 46.81%.

CONCLUSION

Cervical X-ray examination could discover characteristics of nuchal ligament calcification in the relative segment, also is helpful to diagnosis of cervical spondylosis.

Classification of thoracolumbar fractures and dislocations

A classification of injuries is necessary in order to develop a common language for treatment indications and outcomes. Several classification systems have been proposed, the most frequently used is the Denis classification. The problem of this classification system is that it is based on an assumption, which is anatomically unidentifiable: the so-called middle column. For this reason, few years ago, a group of spine surgeons has developed a new classification system, which is based on the severity of the injury. The severity is defined by the pathomorphological findings, the prognosis in terms of healing and potential of neurological damage. This classification is based on three major groups: A = isolated anterior column injuries by axial compression, B = disruption of the posterior ligament complex by distraction posteriorly, and group C = corresponding to group B but with rotation. There is an increasing severity from A to C, and within each group, the severity usually increases within the subgroups from .1, .2, .3. All these pathomorphologies are supported by a mechanism of injury, which is responsible for the extent of the injury. The type of injury with its groups and subgroups is able to suggest the treatment modality.

[The morphological characteristics of osteoarthrosis]

Osteoarthrosis (OA) is a group of overlapping diseases that have various etiologies, but equal biological, morphological, and clinical outcomes. OA is characterized by degenerative and destructive changes in the articular hyaline cartilage, subchondral bone, spongiosis, synovium, capsule, and articular ligamentous apparatus. The clinical symptoms of OA are closely associated with morphological changes in articular tissue elements, primarily in the articular hyaline cartilage. Six stages that reflect the magnitude of changes in the hyaline cartilage and 4 degrees of the extent of the process along the articular surface are identified.

[Iris suture fixation of posterior-chamber elastic intraocular lens in ligament apparatus laxity]

An original MIOL-23 multifocal elastic intraocular lens (IOL) was used to operate 5 eyes with acquired lens dislocation and traumatic cataract. By making self-sealing tunnel incision, ILO was implanted into the capsular sac and sutured to the iris. MIOL-23 implantation caused an increase in mean visual acuity. The IOL took up a correct position. Elastic IOL implantation with iris suture fixation is an efficient and safe mode of additional ILO support.

Successful treatment of meralgia paresthetica with pulsed radiofrequency of the lateral femoral cutaneous nerve

BACKGROUND

Meralgia paresthetica is a rarely encountered sensory mononeuropathy characterized by paresthesia, pain or sensory impairment along the distribution of the lateral femoral cutaneous nerve caused by entrapment or compression of the nerve as it crosses the anterior superior iliac spine and runs beneath the inguinal ligament.

OBJECTIVE

We describe the first reported use of pulsed radiofrequency neuromodulation to relieve the intractable pain associated with meralgia paresthetica.

CASE REPORT

A 33-year-old morbidly obese female with a history of lower back pain and previous spinal fusion presented with sensory dysesthesias and paresthesias in the right anterolateral thigh, consistent with meralgia paresthetica. Temporary relief occurred with multiple lateral femoral cutaneous nerve and fascia lata blocks at 2 different institutions. The patient expressed dissatisfaction with her previous treatments and requested "any" therapeutic intervention that might lead to long-lasting pain relief. At this time, we located the anterior superior iliac spine and reproduced concordant dysesthesia. Pulsed radiofrequency was then undertaken at 42 degrees C for 120 seconds followed by dexamethasone and bupivicaine. The patient reported exceptional and prolonged pain relief at 6-month follow-up.

LIMITATIONS

Since this case report is not a prospective, randomized, controlled or blinded study, no conclusions may be drawn from the results attained on behalf of this single individual. Additional, larger group analyses studying this technique while eliminating bias from patient variables would be essential prior to assuming any validity to using pulsed radiofrequency techniques of neuromodulation for managing peripheral neuropathic pain processes.

CONCLUSION

The patient had experienced long-standing pain that was recalcitrant to conservative/pharmacologic therapy and multiple nerve blocks with local steroid instillations. A single treatment with pulsed radiofrequency resulted in complete and sustained cessation of pain. No side effects were evident. Pulsed radiofrequency of the LFCN may offer an effective, low risk treatment in patients with meralgia paresthetica who are refractory to conservative medical management or are unwilling or unfit to undergo surgery.

Use of the orbicularis retaining ligament in lower eyelid reconstruction

INTRODUCTION

The orbicularis retaining ligament (ORL) is a distinct anatomical structure that has only been recently characterised. A variety of techniques, based on Hamra's concepts, now divide this ligament during lower lid blepharoplasty. This often produces a substantial skin excess which is discarded. We set out to investigate the validity of this surgical manoeuvre as a means of recruiting anterior lamella for the purposes of lower lid reconstruction.

MATERIALS AND METHODS

Between September 2002 and August 2004, 23 patients underwent reconstruction of the anterior lamella of their lower eyelid using this technique. The mean age of the patients was 56 years (range 26-86 years). The mean follow-up time was 20 months (range 12-36 months). Clinical evaluation was carried out preoperatively and postoperatively to assess the presence of palpebral non occlusion, epiphora, the sensation of a dry eye, ectropion, conjunctivitis and keratitis. Assessment of the tissue deficit was made clinically and with standardised digital photographs.

RESULTS

Satisfactory reconstruction of the anterior lamella of the lower eyelid was achieved in 19/23 patients. Preoperative symptoms of epiphora and lower lid position were improved. The visual analogue scale of appearance was improved postoperatively. In some cases, particularly in the atrophic lower lid, the results were short lived and further surgery was required to achieve optimal results.

CONCLUSION

In cases of isolated cutaneous deficit where the lid support mechanisms are intact, the procedure is both successful and aesthetically favourable for resurfacing this challenging area.

Contribution of biomechanics to management of ligament and tendon injuries

The contribution of biomechanics to the advancement of management of ligament and tendon injuries has been significant. Thanks to Professor Y.C. Fung's writing and guidance, our field of research has done fundamental work on anatomy and biology of ligaments and tendons, developed methods to accurately determine mechanical properties, identified various experimental factors which could change the outcome measurements as well as examined biological factors that change tissue properties in-vivo. Professor Fung also gave us his quasi-linear viscoelastic theory for soft tissues so that the time and history dependent properties of ligaments and tendons could be properly described. We have further adopted Professor Fung's eight steps on methods of approach for biomechanical investigation to understand as well as enhance the treatment of ligament and tendon injuries during work or sports related activities. Examples on how to better treat the tears of the medial collateral ligament of the knee, as well as how to improve reconstruction procedures for the anterior cruciate ligament are presented in detail. Currently the use of functional tissue engineering for ligament and tendon healing is a topic of great interest. Here the use of biological scaffolds, such as porcine small intestinal submucosa, has shown promise. For the last 35 to 40 years, the field of biomechanics has made great strides in the treatment of ligament and tendon injuries, and many patients have benefited. The future is even brighter because of what has been done properly in the past. Exciting advances can be made in the field of tissue engineering through novel in-vitro culture and bioscaffold fabrication techniques. Recent technology can also allow the collection of in-vivo data so that ligament and tendon injuries can be better understood. Yet, solving new and more complex problems must still follow the stepwise methods of approach as taught by Professor Fung.

[Angle-closed glaucoma secondary to bilateral spontaneous zonular laxity]

Changeable anterior chamber depth due to spontaneous zonular laxity of the lens is a rare abnormality in clinic. Here is a 25-year-old female with changeable anterior chamber depth due to bilateral spontaneous zonular laxity which also finally led to progressive myopia and angle-closure glaucoma is described. After using local anti-inflammation and dilation of the pupil, and carrying out "Phacoemulsification + anterior vitrectomy" putted intraocular lens (IOL) into the ravine of ciliary body, the woman's intraocular pressure was controlled and visual acuity was corrected to 20/20.

ASB clinical biomechanics award winner 2006 prospective study of the biomechanical factors associated with iliotibial band syndrome

BACKGROUND

Iliotibial band syndrome is the leading cause of lateral knee pain in runners. Despite its high prevalence, little is known about the biomechanics that lead to this syndrome. The purpose of this study was to prospectively compare lower extremity kinematics and kinetics between a group of female runners who develop iliotibial band syndrome compared to healthy controls. It was hypothesized that runners who develop iliotibial band syndrome will exhibit greater peak hip adduction, knee internal rotation, rearfoot eversion and no difference in knee flexion at heel strike. Additionally, the iliotibial band syndrome group were expected to have greater hip abduction, knee external rotation, and rearfoot inversion moments.

METHODS

A group of healthy female recreational runners underwent an instrumented gait analysis and were then followed for two years. Eighteen runners developed iliotibial band syndrome. Their initial running mechanics were compared to a group of age and mileage matched controls with no history of knee or hip pain. Comparisons of peak hip, knee, rearfoot angles and moments were made during the stance phase of running. Variables of interest were averaged over the five running trials, and then averaged across groups.

FINDINGS

The iliotibial band syndrome group exhibited significantly greater hip adduction and knee internal rotation. However, rearfoot eversion and knee flexion were similar between groups. There were no differences in moments between groups.

INTERPRETATION

The development of iliotibial band syndrome appears to be related to increased peak hip adduction and knee internal rotation. These combined motions may increase iliotibial band strain causing it to compress against the lateral femoral condyle. These data suggest that treatment interventions should focus on controlling these secondary plane movements through strengthening, stretching and neuromuscular re-education.

Cervical myelopathy caused by soft-tissue mass in diffuse idiopathic skeletal hyperostosis

A rare case of cervical spinal cord compression in diffuse idiopathic skeletal hyperostosis (DISH or Forestier's Disease) caused by a craniocervical mass of soft-tissue is reported. The objective is to describe an uncommon mechanism of spinal cord compression in DISH. Three weeks after a cardiac infarction a 69-year-old man slowly developed spastic tetraparesis. Magnetic resonance tomography showed a craniocervical tumor compressing the spinal cord and a massive DISH of the cervical spine. An extended mass of yellowish amorphous material was removed from between the dura, the posterior odontoid process and the posterior aspect of vertebral body C2 reaching to the upper part of C3.The histologic appearance indicated connective tissue and cell-degenerated cartilaginous tissue. There was no inflammatory component and no evidence of neoplasia. No ossification of the posterior longitudinal ligament (OPLL) was found. After removal and craniocervical stabilization the patient's neurologic function improved remarkably. The increase of mechanical stress on the atlantoaxial segment and enhanced proliferation reaction of the connective tissue in DISH are suggested as the underlying pathomechanisms in the formation of this soft-tissue mass.

The dual etiology of ipsilateral shoulder pain after thoracic surgery⋆

Ipsilateral shoulder pain after thoracic surgery is a distressing problem and is associated with impairment of respiratory and shoulder function. The most suggested etiology for this shoulder pain is referred phrenic nerve pain. However, we have made clinical observations that suggest shoulder ligament strain as another cause of the shoulder pain.

Ventroaxial luxation of the apex of the corniculate process of the arytenoid cartilage in resting horses during induced swallowing or nasal occlusion

OBJECTIVE

To report ventroaxial luxation of the apex of the left or right corniculate process of the arytenoid cartilage under the contralateral corniculate process during resting endoscopic examination, and morphologic features of the larynx of 1 affected horse.

STUDY DESIGN

Retrospective study.

ANIMALS

Horses (n=8).

METHODS

Horses had endoscopic examination as part of a survey of Clydesdale horses (n=7), or investigation of poor performance in Thoroughbred horses (1). One Clydesdale was euthanatized and the larynx examined; 4 cadaver larynges from normal horses were also examined.

RESULTS

Ventroaxial luxation of the apex of the left or right corniculate process of the arytenoid cartilage was not detected during quiet breathing but was induced by swallowing or nasal occlusion. Prevalence in Clydesdales was 5.2% (7/133). A Thoroughbred with identical endoscopic appearance of the larynx at rest had progressive ventroaxial luxation of the apex of the arytenoid cartilage during high-speed treadmill endoscopy, associated with abnormal respiratory noise. Necropsy examination of an affected Clydesdale larynx revealed an excessively wide (10 mm) transverse arytenoid ligament that allowed easy separation of the apices of the corniculate processes. In normal cadaver larynges, the apices could not be separated with abaxial traction.

CLINICAL RELEVANCE

The clinical relevance of this laryngeal observation in resting horses is unclear. Ventroaxial luxation of the corniculate process of the arytenoid cartilage during induced swallowing or nasal occlusion in resting horses or during high-speed treadmill exercise may be caused by an abnormally wide transverse arytenoid ligament.

Initial repair strengths of two methods for acute medial collateral ligament injuries of the elbow

The purposes of this study were to compare the initial repair strength of the medial collateral ligament (MCL) of the elbow using trans-osseous sutures and suture anchor methods and to determine the effect of repair pretensioning. Twelve, fresh-frozen upper extremities (66 +/- 5 years) were mounted in a valgus-loading system. MCL repairs were performed using trans-osseous suture and suture anchor methods with 20 N or 40 N pretensioning. A cyclic (0.5 Hz), valgus 40 N load was applied 12 cm distal to the elbow axis of flexion. The load was increased by 10 N every 200 cycles until a length increase of 5 mm or catastrophic failure of the repair occurred. Repairs pretensioned with 40 N endured a significantly higher number of cycles and failed at higher loads than those pretensioned with 20 N (p < 0.05). No difference was found in the cycles or load to failure between trans-osseous sutures and suture anchors (p > 0.05). A higher magnitude of pretensioning of MCL repairs was found to increase initial repair strength suggesting that pretensioning should be performed clinically. Despite the comparable failure loads of the trans-osseous suture and suture anchor methods, the failure mechanism differed between the two techniques. The suture anchors usually failed catastrophically when the sutures broke as they passed through the anchor eyelet, while the trans-osseous sutures gradually elongated to the defined failure length by stretching and sliding through the ligament. The use of different suture anchors, suture sizes, or suture materials would likely influence the findings of this study and should be considered when applying these findings clinically.

Hormones and growth factors in the pathogenesis of spinal ligament ossification

Ossification of the spinal ligaments (OSL) is a pathologic condition that causes ectopic bone formation and subsequently results in various degrees of neurological deficit, but the etiology of OSL remains almost unknown. Some systemic hormones, such as 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin and leptin, and local growth factors, such as transforming growth factor-beta (TGF-beta), and bone morphogenetic protein (BMP), have been studied and are thought to be involved in the initiation and development of OSL. This review article summarizes these studies, delineates the possible mechanisms, and puts forward doubts and new questions. The related findings from studies of genes and target cells in the ligament of OSL are also discussed. Although these findings may be helpful in understanding the pathogenesis of OSL, much more research needs to be conducted in order to investigate the nature of OSL.

Active Range of Motion as an Indicator for Ligament and Membrane Lesions in the Upper Cervical Spine after a Whiplash Trauma

In the present study, we examined whether active range of neck motion (AROM) differed between persons with and without a diagnosis of whiplash-associated disorder type 2 (WAD2) and explored whether magnetic resonance (MR)-verified lesions of specific ligaments or membranes at the craniovertebral junction was associated with increased or decreased motion in any particular direction among the WAD2 patients. A CROM goniometer was used for registration of flexion, extension, side bending (left and right) and rotation (left and right), respectively. The neck structures considered were the alar and the transverse ligaments, and the tectorial and the posterior atlanto-occipital membranes. Our study comprised 87 WAD2 patients and 29 control persons without any known neck injury. For comparing mean values of AROM between the groups, t-test and analysis of variance (ANOVA) were used. WAD patients had on average a shorter range of active motion for all movements compared with the control group. The difference was statistically significant for all measures considered, except side bending to the left. Among the WAD patients, increasing severity of lesions to the alar ligaments was associated with a decrease in maximal flexion and rotation. A similar pattern was seen for lesions to the transverse ligament, but the trend test was not significant. An abnormal posterior atlanto-occipital membrane was associated with shorter range of left rotation, with a significant trend test both in analyses with and without adjustment for lesions to other structures. No significant association was found in relation to lesions to the tectorial membrane, but very few persons had such lesions. These findings indicate that soft tissue lesions may affect neck motion as reflected by AROM. However, since lesions to different structures seem to affect the same movement, AROM alone is not a sufficient indicator for soft-tissue lesions to specific structure in the upper cervical spine.

Nonlinear finite element analysis for musculoskeletal biomechanics of medial and lateral plantar longitudinal arch of Virtual Chinese Human after plantar ligamentous structure failures

BACKGROUND

Musculoskeletal diseases of the foot such as stress fractures, tendonitis and subsequent pain are commonly associated with elevated stresses/strains of abnormal plantar arch after plantar ligamentous structure failures. The goal of this study was to develop anatomically detailed, finite element models of the medial and lateral plantar longitudinal arch, and to investigate bone and muscle stresses resulting from plantar fasciotomy and major plantar ligament injuries.

METHODS

Nonlinear finite element models of the second ray and the fifth ray of plantar longitudinal arches were constructed on the basis of CT and MR images of Virtual Chinese Human "female No. 1". The models assumed a balanced standing load configuration. Three different degrees of passive intrinsic muscle tensions (weak, moderate, or severe) were used in conjunction with simulations of plantar fasciotomy and major plantar ligament injury.

FINDINGS

Plantar fasciotomy caused von Mises stress increases in the bones and plantar ligaments while major plantar ligament injuries caused stress increases in the bones, flexor tendons, and plantar fascia. Increasing intrinsic muscle passive tensions decreased stress/strain levels in the medial and lateral arch, and adjusted abnormal tension/compression stress flows of both arches to close to the normal biomechanical states.

INTERPRETATION

This study shows that plantar longitudinal arches are concordant combination of bony structures, intrinsic muscles, plantar fascia and ligaments. After plantar ligamentous structure failures, intrinsic muscles have to contribute to stabilize the plantar arches. This mechanism may reduce the risk of developing stress fractures, tendonitis and pain syndrome.

Neck ligament strength is decreased following whiplash trauma

Background

Previous clinical studies have documented successful neck pain relief in whiplash patients using nerve block and radiofrequency ablation of facet joint afferents, including capsular ligament nerves. No previous study has documented injuries to the neck ligaments as determined by altered dynamic mechanical properties due to whiplash. The goal of the present study was to determine the dynamic mechanical properties of whiplash-exposed human cervical spine ligaments. Additionally, the present data were compared to previously reported control data. The ligaments included the anterior and posterior longitudinal, capsular, and interspinous and supraspinous ligaments, middle-third disc, and ligamentum flavum.

Methods

A total of 98 bone-ligament-bone specimens (C2–C3 to C7-T1) were prepared from six cervical spines following 3.5, 5, 6.5, and 8 g rear impacts and pre- and post-impact flexibility testing. The specimens were elongated to failure at a peak rate of 725 (SD 95) mm/s. Failure force, elongation, and energy absorbed, as well as stiffness were determined. The mechanical properties were statistically compared among ligaments, and to the control data (significance level: P < 0.05; trend: P < 0.1). The average physiological ligament elongation was determined using a mathematical model.

Results

For all whiplash-exposed ligaments, the average failure elongation exceeded the average physiological elongation. The highest average failure force of 204.6 N was observed in the ligamentum flavum, significantly greater than in middle-third disc and interspinous and supraspinous ligaments. The highest average failure elongation of 4.9 mm was observed in the interspinous and supraspinous ligaments, significantly greater than in the anterior longitudinal ligament, middle-third disc, and ligamentum flavum. The average energy absorbed ranged from 0.04 J by the middle-third disc to 0.44 J by the capsular ligament. The ligamentum flavum was the stiffest ligament, while the interspinous and supraspinous ligaments were most flexible. The whiplash-exposed ligaments had significantly lower (P = 0.036) failure force, 149.4 vs. 186.0 N, and a trend (P = 0.078) towards less energy absorption capacity, 308.6 vs. 397.0 J, as compared to the control data.

Conclusion

The present decreases in neck ligament strength due to whiplash provide support for the ligament-injury hypothesis of whiplash syndrome.

The Mechanisms of Atrial Fibrillation

In this article we have reviewed the mechanisms of atrial fibrillation (AF) with special emphasis on the thoracic veins. Based on a number of features, the thoracic veins are highly arrhythmogenic. The pulmonary vein (PV)-left atrial (LA) junction has discontinuous myocardial fibers separated by fibrotic tissues. The PV muscle sleeve is highly anisotropic. The vein of Marshall (VOM) in humans has multiple small muscle bundles separated by fibrosis and fat. Insulated muscle fibers can promote reentrant excitation, automaticity, and triggered activity. The PV muscle sleeves contain periodic acid-Schiff (PAS)-positive large pale cells that are morphologically reminiscent of Purkinje cells. These special cells could be the sources of focal discharge. Antiarrhythmic drugs have significant effects on PV muscle sleeves both at baseline and during AF. Both class I and III drugs have effects on wavefront traveling from PV to LA and from LA to PV. Separating the thoracic veins and the LA with ablation techniques also prevents PV-LA interaction. By reducing PV-LA interaction, pharmacological therapy and PV isolation reduce the activation rate in PV, intracellular calcium accumulation, and triggered activity. Therefore, thoracic vein isolation is an important technique in AF control. We conclude that thoracic veins are important in the generation and maintenance of AF.

Sensory – Motor control of ligaments and associated neuromuscular disorders

The ligaments were considered, over several centuries, as the major restraints of the joints, keeping the associated bones in position and preventing instability, e.g. their separation from each other and/or mal-alignment. This project, conducted over 25 years, presents the following hypothesis: 1. Ligaments are also major sensory organs, capable of monitoring relevant kinesthetic and proprioceptive data. 2. Excitatory and inhibitory reflex arcs from sensory organs within the ligaments recruit/de-recruit the musculature to participate in maintaining joint stability as needed by the movement type performed. 3. The synergy of the ligament and associated musculature allocates prominent role for muscles in maintaining joint stability. 4. The viscoelastic properties of ligaments and their classical responses to static and cyclic loads or movements such as creep, tension-relaxation, hysteresis and strain rate dependence decreases their effectiveness as joint restraint and stabilizers and as sensory organs and exposes the joint to injury. 5. Long-term exposure of ligaments to static or cyclic loads/movements in a certain dose-duration paradigms consisting of high loads, long loading duration, high number of load repetitions, high frequency or rate of loading and short rest periods develops acute inflammatory responses which require long rest periods to resolve. These inflammatory responses are associated with a temporary (acute) neuromuscular disorder and during such period high exposure to injury is present. 6. Continued exposure of an inflamed ligament to static or cyclic load may result in a chronic inflammation and the associated chronic neuromuscular disorder known as cumulative trauma disorder (CTD). 7. The knowledge gained from basic and applied research on the sensory - motor function of ligaments can be used as infrastructure for translational research; mostly for the development of "smart orthotic" systems for ligament deficient patients. Three such "smart orthosis", for the knee and lumbar spine are described. 8. The knowledge gained from the basic and applied research manifests in new physiotherapy modalities for ligament deficient patients. Ligaments, therefore, are important structures with significant impact on motor control and a strong influence on the quality of movement, safety/stability of the joint and potential disorders that impact the safety and health of workers and athletes.

Dual-portal endoscopic release of the transverse ligament in carpal tunnel syndrome: results of 411 procedures with special reference to technique, efficacy, and complications

OBJECTIVE

Endoscopic release of carpal tunnel syndrome is still under debate. The main advantages of the technique are considered to be minor postoperative pain and a more rapid postoperative recovery. Disadvantages are thought to be the impossibility of a direct median nerve neurolysis and a higher surgical complication rate, including injury to the median nerve.

METHODS

The results of 411 consecutive endoscopic carpal tunnel procedures performed between March 1995 and September 2004 are presented. All patients were prospectively followed.

RESULTS

In the present series, a success rate of 98.05% was observed. There was no permanent morbidity and, in particular, there was no injury of the median nerve. In four (0.97%) patients, the preoperative symptoms did not improve. In two (0.49%) of these patients, an incomplete release of the carpal ligament occurred. In another four patients (0.97%), a switch to open surgery was required.

CONCLUSION

The present data prove that the endoscopic technique is a safe and reliable technique for carpal tunnel surgery. The data do not support the current discussion of a higher risk of median nerve injury with endoscopic carpal tunnel surgery. Thus, for our group, the endoscopic technique represents the therapy of choice for the primary idiopathic carpal tunnel syndrome.