A 15-year study of osseointegrated implants in the treatment of the edentulous jaw

Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms.

In an attempt to explain how and why some individuals with musculoskeletal pain develop a chronic pain syndrome, Lethem et al. (Lethem J, Slade PD, Troup JDG, Bentley G. Outline of fear-avoidance model of exaggerated pain perceptions. Behav Res Ther 1983; 21: 401-408).ntroduced a so-called 'fear-avoidance' model. The central concept of their model is fear of pain. 'Confrontation' and 'avoidance' are postulated as the two extreme responses to this fear, of which the former leads to the reduction of fear over time. The latter, however, leads to the maintenance or exacerbation of fear, possibly generating a phobic state. In the last decade, an increasing number of investigations have corroborated and refined the fear-avoidance model. The aim of this paper is to review the existing evidence for the mediating role of pain-related fear, and its immediate and long-term consequences in the initiation and maintenance of chronic pain disability. We first highlight possible precursors of pain-related fear including the role negative appraisal of internal and external stimuli, negative affectivity and anxiety sensitivity may play. Subsequently, a number of fear-related processes will be discussed including escape and avoidance behaviors resulting in poor behavioral performance, hypervigilance to internal and external illness information, muscular reactivity, and physical disuse in terms of deconditioning and guarded movement. We also review the available assessment methods for the quantification of pain-related fear and avoidance. Finally, we discuss the implications of the recent findings for the prevention and treatment of chronic musculoskeletal pain. Although there are still a number of unresolved issues which merit future research attention, pain-related fear and avoidance appear to be an essential feature of the development of a chronic problem for a substantial number of patients with musculoskeletal pain.

/pdf/fear-avoidance-and-its-consequences-in-chronic-25jwj42o35.pdf

Fear-avoidance and its consequences in chronic musculoskeletal pain: a state of the art

&NA; In an attempt to explain how and why some individuals with musculoskeletal pain develop a chronic pain syndrome, Lethem et al.(Lethem J, Slade PD, Troup JDG, Bentley G. Outline of fear‐avoidance model of exaggerated pain perceptions. Behav Res Ther 1983; 21: 401‐408).ntroduced a so‐called ‘fear‐avoidance’ model. The central concept of their model is fear of pain. ‘Confrontation’ and ‘avoidance’ are postulated as the two extreme responses to this fear, of which the former leads to the reduction of fear over time. The latter, however, leads to the maintenance or exacerbation of fear, possibly generating a phobic state. In the last decade, an increasing number of investigations have corroborated and refined the fear‐avoidance model. The aim of this paper is to review the existing evidence for the mediating role of pain‐related fear, and its immediate and long‐term consequences in the initiation and maintenance of chronic pain disability. We first highlight possible precursors of pain‐related fear including the role negative appraisal of internal and external stimuli, negative affectivity and anxiety sensitivity may play. Subsequently, a number of fear‐related processes will be discussed including escape and avoidance behaviors resulting in poor behavioral performance, hypervigilance to internal and external illness information, muscular reactivity, and physical disuse in terms of deconditioning and guarded movement. We also review the available assessment methods for the quantification of pain‐related fear and avoidance. Finally, we discuss the implications of the recent findings for the prevention and treatment of chronic musculoskeletal pain. Although there are still a number of unresolved issues which merit future research attention, pain‐related fear and avoidance appear to be an essential feature of the development of a chronic problem for a substantial number of patients with musculoskeletal pain.

Fear-avoidance and its consequences in chronic musculoskeletal pain: a state of the art.

Pilot studies and a literature review suggested that fear-avoidance beliefs about physical activity and work might form specific cognitions intervening between low back pain and disability. A Fear-Avoidance Beliefs Questionnaire (FABQ) was developed, based on theories of fear and avoidance behaviour and focussed specifically on patients' beliefs about how physical activity and work affected their low back pain. Test-retest reproducibility in 26 patients was high. Principal-components analysis of the questionnaire in 210 patients identified 2 factors: fear-avoidance beliefs about work and fear-avoidance beliefs about physical activity with internal consistency (alpha) of 0.88 and 0.77 and accounting for 43.7% and 16.5% of the total variance, respectively. Regression analysis in 184 patients showed that fear-avoidance beliefs about work accounted for 23% of the variance of disability in activities of daily living and 26% of the variance of work loss, even after allowing for severity of pain; fear-avoidance beliefs about physical activity explained an additional 9% of the variance of disability. These results confirm the importance of fear-avoidance beliefs and demonstrate that specific fear-avoidance beliefs about work are strongly related to work loss due to low back pain. These findings are incorporated into a biopsychosocial model of the cognitive, affective and behavioural influences in low back pain and disability. It is recommended that fear-avoidance beliefs should be considered in the medical management of low back pain and disability.

A Fear-Avoidance Beliefs Questionnaire (FABQ) and the role of fear-avoidance beliefs in chronic low back pain and disability

A compression testing machine was used to transmit increasing loads at various strain rates across twelve canine and twelve human cadaver knees. The specimens were originally evaluated with both menisci intact and the same tests were repeated with one meniscus removed and then with both menisci removed. This investigation showed that the menisci perform a load-transmitting and energy-absorbing function in the knee joint. The stress acting across the joint increased significantly after meniscectomy. The intact meniscus was deformed during compressive loading rather than being passively pushed away, thus demonstrating the presence of hoop stresses within the meniscus.

Mechanical changes in the knee after meniscectomy.

The objectives of this study were to measure strain in the ACL during simulated: hamstring activity alone, quadriceps activity alone, and simultaneous quadriceps and hamstring activity. Seven knee specimens removed from cadavers were studied. Heavy sutures applied to load cells were attached to the hamstring and quadriceps tendons. Loads were then applied manually (hamstrings) and/or with an Instron testing machine (quadriceps) to simulate isometric contractions of the various muscle groups. Strain was measured using a Hall effect transducer. Acting alone, the isometric hamstring activity decreased ACL strain relative to the passive normal strain at all positions tested. Thus, hamstring exercises are not detrimental to ACL repairs or reconstruction and can be included early in the rehabilitation program after ACL surgery. Acting alone, at flexion angles of 0 degree to 45 degrees, the quadriceps significantly increased the strain within the ACL relative to the passive normal strain. Strain in the ACL during simultaneous hamstring and quadriceps activity was significantly higher than that during passive normal motion from full extension to 30 degrees of flexion. The hamstrings are not capable of masking the potentially harmful effects of simultaneous quadriceps contraction on freshly repaired or reconstructed ACLs unless the knee flexion angle exceeds 30 degrees.

Strain within the anterior cruciate ligament during hamstring and quadriceps activity

The rehabiliation of knee injuries involving the anterior cruciate ligament (ACL) is controversial. This paper describes strain in the normal and reconstructed ACL during a series of passive and active tests of knee flexion with and without varus, valgus and axial rotation torques on the tibia.

The biomechanics of anterior cruciate ligament rehabilitation and reconstruction

Before studying the biomechanical effects of rehabilitation exercises on the reconstructed knee, it is important to understand their effects on the normal anterior cruciate ligament. The objective of this investigation was to measure the strain behavior of this ligament during rehabilitation activities in vivo. Participants were patient volunteers with normal anterior cruciate ligaments instrumented with the Hall effect transducer. At 10 degrees and 20 degrees of flexion, ligament strain values for active extension of the knee with a weight of 45 N applied to a subject's lower leg were significantly greater than active motion without the weight. Isometric quadriceps muscle contraction at 15 degrees and 30 degrees also produced a significant increase in ligament strain, while at 60 degrees and 90 degrees of knee flexion there was no change in ligament strain relative to relaxed muscle condition. Simultaneous quadriceps and hamstrings muscles contraction at 15 degrees produced a significant increase in ligament strain compared with the relaxed state but did not strain the ligament at 30 degrees, 60 degrees, and 90 degrees of flexion. Isometric contraction of hamstrings muscles did not produce change in ligament strain at any flexion angle. Exercises that produce low or unstrained ligament values, and would not endanger a properly implanted graft, are either dominated by the hamstrings muscle (isometric hamstring), involve quadriceps muscle activity with the knee flexed at 60 degrees or greater (isometric quadriceps, simultaneous quadriceps and hamstrings contraction), or involve active knee motion between 35 degrees and 90 degrees of flexion.

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises In Vivo

This study examined the role of facet joint morphology in the etiology of both degenerative spondylolisthesis and isthmic spondylolysis. To this end, the axial facet joint morphology of the lower lumbar spine in a normal population and in populations of patients with spinal stenosis or degenerative spondylolisthesis at L4-5 and in patients with isthmic spondylolysis at the L5 level were characterized. Computed tomographic scans were digitized, defining the axial morphology of the normal facet joint at five stations from proximal to distal within the joint. Assessments were made of facet joint orientation, transverse articular dimension, depth of the articular surface, and shape of the articular surface at levels L3-4, L4-5, and L5-S1. There was a gradually more coronal orientation from proximal to distal among the stations at each level, and a maximal transverse articular dimension at the level of the superior endplate of the caudad vertebra. Minimal error in the recording process at this level. In addition to the maximal joint dimension, made this level the most representative of the overall morphology and most useful for further studies. At the L4-5 level, a significantly more sagittal facet orientation was found in the degenerative spondylolisthesis group when compared to both the normal population and spinal stenosis groups (P < 0.01). At L5-S1, the only significant morphologic difference between the normal population and the patients with isthmic spondylolysis was reduced transverse articular dimension. These results support the hypothesis that patients developing degenerative spondylolisthesis are predisposed to this by a developmental sagittal orientation of the L4-5 facet joints.

Malcolm H. Pope

Papers

Mechanical changes in the knee after meniscectomy.

Strain within the anterior cruciate ligament during hamstring and quadriceps activity

The biomechanics of anterior cruciate ligament rehabilitation and reconstruction

Anterior Cruciate Ligament Strain Behavior During Rehabilitation Exercises In Vivo

Etiology of spondylolisthesis. Assessment of the role played by lumbar facet joint morphology.