Occurrence and distribution of free nerve endings in the distal iliotibial tract system of the knee

Differential Sensitization of Muscle versus Fascia in Individuals with Low Back Pain

Muscles and the deep fascia surrounding them have been suggested to play an important role in various musculoskeletal pain conditions including low back pain. Both have been shown to host rich nociceptive innervation and to undergo changes in individuals with chronic pain. However, evidence for the respective contribution of muscle and fascia sensitization in humans with myofascial pain syndrome is lacking. Here, we studied the sensitization of muscle and fascia in individuals with myofascial low back pain. Twenty individuals with acute (5) and chronic (15) myofascial low back pain of the quadratus lumborum muscle and a matched control group of twenty healthy individuals were recruited and clinically evaluated. All participants underwent ultrasound-guided needling of their subcutaneous tissue, deep fascia and quadratus lumborum muscle. Reported pain intensity and episodes of muscle twitching were recorded and analyzed. Among pain patients, both muscles and deep fascia demonstrated pain hypersensitivity, but muscles were significantly more sensitized than the deep fascia. No difference between acute- or chronic-pain patients was observed. Results of this study suggest that while both deep fascia and muscle show pain sensitization in both early and chronic stages of low back pain, muscles are more sensitized than fascia.

The Deep Fascia and its Role in Chronic Pain & Pathological Conditions: A Review

INTRODUCTION

The deep fascia is a three-dimensional continuum of connective tissue surrounding the bones, muscles, nerves and blood vessels throughout our body. Its importance in chronically debilitating conditions has recently been brought to light. This work investigates changes in these tissues in pathological settings.

MATERIALS AND METHODS

A state-of-the-art review was conducted in PubMed and Google Scholar following a two-stage process. A first search was performed to identify main types of deep fasciae. A second search was performed to identify studies considering a deep fascia, common pathologies of this deep fascia and the associated alterations in tissue anatomy.

RESULTS

We find that five main deep fasciae pathologies are chronic low back pain, chronic neck pain, Dupuytren's disease, plantar fasciitis and iliotibial band syndrome. The corresponding fasciae are respectively the thoracolumbar fascia, the cervical fascia, the palmar fascia, the plantar fascia and the iliotibial tract. Pathological fascia is characterized by increased tissue stiffness along with alterations in myofibroblast activity and the extra-cellular matrix, both in terms of collagen and Matrix Metalloproteases (MMP) levels. Innervation changes such as increased density and sensitization of nociceptive nerve fibers are observed. Additionally, markers of inflammation such as pro-inflammatory cytokines and immune cells are documented. Pain originating from the deep fascia likely results from a combination of increased nerve density, sensitization and chronic nociceptive stimulation, whether physical or chemical.

CONCLUSIONS

The pathological fascia is characterized by changes in innervation, immunology and tissue contracture. Further investigation is required to best benefit both research opportunities and patient care.

Impact of medial versus lateral knee pain on deep tissue hyperalgesia and muscle strength

BACKGROUND

Accumulating evidence indicates that knee pain gives rise to sensory and motor alterations, however, whether different profile of knee pain causes different alterations has not been investigated. The purpose of this experimental study is to clarify characteristics of medial and lateral knee pain and its potential for modulating sensory and motor function in humans.

METHODS

Fourteen healthy men were included. Medial knee pain (MP) was induced by injection of hypertonic saline (0.5 mL) into the tibial insertion of the medial collateral ligament. For comparison, lateral knee pain (LP) was induced by injection of hypertonic saline identically into the iliotibial tract. Isotonic saline was injected contralaterally as control. Pain intensity was assessed on a continuous electronic visual analogue scale (VAS). Before, during and after the painful state, pressure pain thresholds from the knee (PPTs), maximal isometric muscle strength of the quadriceps and grip power were assessed bilaterally.

RESULTS

MP demonstrated significantly higher VAS scores than LP and compared with control. PPTs decreased on medial and lateral knee in MP but only on the lateral knee in LP. Quadriceps muscle strength and grip power reduced bilaterally in both models, however, MP caused significantly greater reduction of ipsilateral quadriceps strength compared with LP.

CONCLUSION

Medial knee pain has a greater impact on deep tissue hyperalgesia and reduction of the muscle strength compared with lateral knee pain. This is a novel finding that should be taken into consideration in a treatment strategy for painful knee patients.

SIGNIFICANCE

The experimental medial knee pain model demonstrated higher pain intensity, more localized pain distribution, widespread deep tissue hyperalgesia and more severe inhibition of muscle strength compared with the lateral knee pain model.

Periarticular Injections in Knee and Hip Arthroplasty: Where and What to Inject

BACKGROUND

Periarticular injections have become a valuable adjunct to multimodal pain control regimens after knee and hip arthroplasties. Injection techniques vary greatly among surgeons with little standardization of practice.

METHODS

We performed an extensive literature search to determine where nociceptive pain fibers are located in the hip and the knee and also to explore the pharmacology of periarticular cocktail ingredients.

RESULTS

Large concentrations of nociceptors are present throughout the various tissues of the knee joint with elevated concentrations in the infrapatellar fat pad, fibrous capsule, ligament insertions, periosteum, subchondral bone, and lateral retinaculum. Less empiric evidence is available on nociceptor locations in the hip joint, but they are known to be located diffusely throughout the hip capsule with elevated concentrations at the labral base and central ligamentum teres. Local anesthetics are the base ingredient in most injection cocktails and function by blocking voltage-gated sodium channels. Liposomal anesthetics may offer longer duration of action over traditional anesthetics. Nonsteroidal anti-inflammatory agents and corticosteroids block peripheral production of inflammatory mediators and may desensitize nociceptors. Opioid receptors are present in lower densities peripherally as compared with the central nervous system, but their inclusion in injections can lead to pain relief. Sympathetic drugs can provide adjunct effects to periarticular cocktails to increase duration of action and effectiveness of medications.

CONCLUSION

Targeting specific sites of nociceptors may help to further decrease pain after knee and hip arthroplasties. Altering periarticular cocktail ingredients may aid in multimodal pain control with injections.

The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee

BACKGROUND

Anterolateral rotatory instability (ALRI) may result from combined anterior cruciate ligament (ACL) and lateral extra-articular lesions, but the roles of the anterolateral structures remain controversial.

PURPOSE

To determine the contribution of each anterolateral structure and the ACL in restraining simulated clinical laxity in both the intact and ACL-deficient knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 16 knees were tested using a 6 degrees of freedom robot with a universal force-moment sensor. The system automatically defined the path of unloaded flexion/extension. At different flexion angles, anterior-posterior, internal-external, and internal rotational laxity in response to a simulated pivot shift were tested. Eight ACL-intact and 8 ACL-deficient knees were tested. The kinematics of the intact/deficient knee was replayed after transecting/resecting each structure of interest; therefore, the decrease in force/torque reflected the contribution of the transected/resected structure in restraining laxity. Data were analyzed using repeated-measures analyses of variance and paired t tests.

RESULTS

For anterior translation, the intact ACL was clearly the primary restraint. The iliotibial tract (ITT) resisted 31% ± 6% of the drawer force with the ACL cut at 30° of flexion; the anterolateral ligament (ALL) and anterolateral capsule resisted 4%. For internal rotation, the superficial layer of the ITT significantly restrained internal rotation at higher flexion angles: 56% ± 20% and 56% ± 16% at 90° for the ACL-intact and ACL-deficient groups, respectively. The deep layer of the ITT restrained internal rotation at lower flexion angles, with 26% ± 9% and 33% ± 12% at 30° for the ACL-intact and ACL-deficient groups, respectively. The other anterolateral structures provided no significant contribution. During the pivot-shift test, the ITT provided 72% ± 14% of the restraint at 45° for the ACL-deficient group. The ACL and other anterolateral structures made only a small contribution in restraining the pivot shift.

CONCLUSION

The ALL and anterolateral capsule had a minor role in restraining internal rotation; the ITT was the primary restraint at 30° to 90° of flexion.

CLINICAL RELEVANCE

The ITT showed large contributions in restraining anterior subluxation of the lateral tibial plateau and tibial internal rotation, which constitute pathological laxity in ALRI. In cases with ALRI, an ITT injury should be suspected and kept in mind if an extra-articular procedure is performed.

The assessment of the cervical spine. Part 1: Range of motion and proprioception

Neck pain and headache of cervical origin are complaints affecting an increasing number of the general population. Mechanical factors such as sustained neck postures or movements and long-term "abnormal" physiologic loads on the neck are believed to affect the cervical structures and compromise neck function. A comprehensive assessment of neck function requires evaluation of its physical parameters such as range of motion, proprioception, strength and endurance/fatigue. The complicated structure of the cervical spine however, makes it difficult for any clinician to obtain reliable and valid results. The aim of the first part of this systematic critical review is to identify the factors influencing the assessment of range of motion and proprioception of the cervical spine.

Idiopathic anterior knee pain in adolescents

Anterior knee pain is a common problem and its management can be challenging. A thorough evaluation of the patient's history and examination of the lower extremity and knee extensor mechanism is necessary. Clinically elusive conditions should be considered before ascribing the pain as idiopathic, the most common diagnosis of adolescent anterior knee pain. In the majority of cases, the natural history of idiopathic anterior knee pain is improvement and resolution. Nonoperative therapeutic measures usually provide improved knee function.

Proprioceptive training and prevention of anterior cruciate ligament injuries in soccer

This commentary describes a program developed to help reduce the incidence of anterior cruciate ligament injuries in soccer players. The basic principles underlying the injury prevention protocol are described with respect to the proprioceptive control mechanisms at the knee joint. This is followed by a detailed description of the program.

Proprioception and joint stability

In the present paper the current clinical knowledge about proprioception is given for the shoulder, knee, ankle, elbow and the radiocarpal joint. Proprioceptive capabilities are decreased after joint injuries such as ACL or meniscus tears, shoulder dislocation, ankle sprain and in joints with degenerative joint disease. Some surgical procedures seem to restore the proprioceptive abilities; others do not. Elastic knee bandages or ankle braces increase different proprioceptive factors like ankle reproduction capability or sports-specific abilities. The present information on proprioception will influence our clinical practice in the future. We should choose surgical procedures that not only reconstruct the anatomy, but also the neurophysiologic feed-back mechanism.