Gail Durbridge

The association between degenerative hip joint pathology and size of the gluteus medius, gluteus minimus and piriformis muscles

This study aimed to investigate changes in the deep abductor muscles, gluteus medius (GMED), piriformis (PIRI), and gluteus minimus (GMIN), occurring in association with differing stages of unilateral degenerative hip joint pathology (mild: n=6, and advanced: n=6). Muscle volume assessed via magnetic resonance imaging was compared for each muscle between sides, and between groups (mild, advanced, control (n=12)). GMED and PIRI muscle volume was smaller around the affected hip in subjects with advanced pathology (p<0.01, p<0.05) while no significant asymmetry was present in the mild and control groups. GMIN showed a trend towards asymmetry in the advanced group (p=0.1) and the control group (p=0.076) which appears to have been associated with leg dominance. Between group differences revealed a significant difference for the GMED muscle reflecting larger muscle volumes on the affected side in subjects with mild pathology, compared to matched control hips. This information suggests that while GMED appears to atrophy in subjects with advanced hip joint pathology, it may be predisposed to hypertrophy in early stages of pathology. Assessment and exercise prescription methods should consider that the response of muscles of the abductor synergy to joint pathology is not homogenous between muscles or across stages of pathology.

Altered white matter diffusion anisotropy in normal and preterm infants at term equivalent age

To investigate white matter (WM) development, voxelwise analyses of diffusion tensor MRI (DTMRI) data, acquired from 12 very preterm and 11 preterm infants with gestational ages (GA) ranging from 25 to 29 and 29 to 32 weeks, respectively, and 10 newborn normal term infants were performed. T2 relaxation measures were also generated to assess brain water content. Compared with newborn term infants, very preterm infants were found to possess reduced fractional anisotropy (FA) within the frontal lobe, and a number of anterior and posterior commissural pathways. Preterm infants possessed reduced FA mainly within the posterior regions of the corpus callosum. Unexpectedly, we observed significantly reduced FA and increased T2 within a number of corticospinal projections in the newborn term infants compared to the preterm groups. This finding may reflect increased water concentration and/or a lowering of FA due to the presence of crossing interhemispheric WM projections. These findings indicate that care should be taken when interpreting FA indices without knowledge of the possible effects of water concentration in the newborn infant brain. Magn Reson Med 60:761–767, 2008.

The association between degenerative hip joint pathology and size of the gluteus maximus and tensor fascia lata muscles

The aim of this study was to obtain, using Magnetic Resonance Imaging (MRI), muscle volume measurements for the gluteus maximus (upper: UGM and lower: LGM portions) and tensor fascia lata (TFL) muscles in both healthy subjects (n=12) and those with unilateral osteoarthritis (OA) of the hip (mild: n=6, and advanced: n=6). While control group subjects were symmetrical between sides for the muscles measured, subjects with hip joint pathology showed asymmetry in GM muscle volume dependent on stage of pathology. The LGM demonstrated atrophy around the affected hip in subjects with advanced pathology (p<0.05), however asymmetry of the UGM (p<0.01) could be attributed largely to hypertrophy on the unaffected side, based on between group comparisons of muscle volume. TFL showed no significant asymmetry, or difference compared to the normal control group. This study highlights the functional separation of UGM and LGM, and the similarities of the UGM and TFL, both superficial abductors appearing to maintain their size around the affected hip. Further research is required to determine the specific changes occurring in the deeper abductor muscles. This information may assist in the development of more targeted and effective exercise programmes in the management of OA of the hip.

Craniocervical orientation affects muscle activation when exercising the cervical extensors in healthy subjects

OBJECTIVE To evaluate the activity of neck extensor muscles during different extension exercises with muscle functional magnetic resonance imaging (mfMRI). DESIGN Cross-sectional. SETTING University laboratory. PARTICIPANTS Healthy subjects (N=11; 7 men, mean age +/- SD, 34+/-5.6y; 4 women, mean age +/- SD, 23.3+/-5.2y; group mean age +/- SD, 30.1+/-7.5y). INTERVENTION Not applicable. MAIN OUTCOME MEASURES mfMRI measures of T2 relaxation were made for the multifidus (Mul), the semispinalis cervicis (SCe), the semispinalis capitis (SCa), and the splenius capitis (SpC) at C2-3, C5-6, and C7-T1 in response to 2 head/neck orientations: craniocervical neutral (CCN) and craniocervical extension (CCE). Subjects performed three 1-minute repetitions of each condition at 20% maximum voluntary contraction. RESULTS Significant shifts were observed in all muscle groups at the C5-6 and C7-T1 levels after both conditions (P=.04) except the SpC muscle at C5-6 with CCN (P=.17). T2 shifts in the SCa were significantly greater in response to CCE than CCN at C2-3 (P=.03) and C5-6 (P=.02). Similarly, CCE resulted in larger shifts than CCN in the Mul/SCe at C7-T1 (P=.003). No segmental differences were observed between exercises for SpC (P=.25). CONCLUSIONS The results of this study provide some preliminary insight into the impact of craniocervical orientation on the differential response of the deep and superficial cervical extensor muscles during the performance of cervical extensor exercises.

Magnetic Resonance Imaging: Fundamental Safety Issues

SYNOPSIS Medical practitioners have a variety of imaging modalities at their disposal. The exquisite soft tissue delineation available with magnetic resonance imaging (MRI) has resulted in the rising utilization of this particular modality. Increasingly, physical therapists around the world are actively involved in not only referring patients with musculoskeletal conditions for MRI but also in the acquisition of MRI data in both the clinical and research arenas. The MRI process involves the use of a very strong static magnetic field, time-varying (gradient) fields, and radiofrequency energy. To ensure the well-being of patients, staff, and visitors, an understanding of the primary hazards of this environment and the rigorous safety procedures that must be followed is imperative to the clinician. This paper describes the basic components of an MRI system, discusses various MRI safety issues, and presents the screening procedure necessary prior to using MRI. Primary hazards associated with the imaging process are also reviewed. J Orthop Sports Phys Ther 2011;41(11):820-828. doi:10.2519/jospt.2011.3906.

Dorsal Digital Septum of the Distal Interphalangeal Joint

PURPOSE Clinical observation has led to the discovery of a distinct anatomic septum from the extensor tendon to the skin at the distal phalanx that appears to limit the proximal spread of infection from the dorsum of the distal phalanx. This study employed histology and high-resolution magnetic resonance imaging (MRI) to identify this anatomic structure at the level of the distal interphalangeal (DIP) joint. METHODS We used high-resolution (16.4-T) MRI to image and section 10 cadaveric fingers (9 female, 1 male) from both left and right hands. Once imaged, we made histologic sections using hematoxylin and eosin, or Van Giesons stain, and examined them microscopically for concordant findings. RESULTS In all 10 scans, the proposed septum was visualized using MRI with histologic confirmation. It was observed to extend from the skin creases overlying the dorsal aspect of the DIP joint to the extensor tendon. It is composed of collagen bundles arranged in a variable network that adhere extensor tendon to skin at the DIP joint. CONCLUSIONS Clinical observations proposed the existence of a distinct septum between extensor tendon and skin at the level of the DIP joint. We confirmed this structure to be a collagen septum by MRI and histology. This previously undescribed structure is called the dorsal septum.

The connective tissue and ligaments of the distal interphalangeal joint: a review and investigation using ultra-high field 16.4 Tesla magnetic resonance imaging

This study reviews the literature on the anatomy of the connective tissues surrounding the distal interphalangeal joint and further characterizes the three-dimensional relationships of these structures with ultra-high field magnetic resonance imaging. Ten cadaver fingers, fixed in a solution of 5% agar and 4% formalin, were imaged utilising an ultrashield 16.4 Tesla ultra-high field magnetic resonance imaging, yielding a total of 4000 images. Images were analysed using Osirix™ (version 5.5.1 32 bit edition) for three-dimensional reconstruction. We found numerous conflicting descriptions of the connective tissue structures around the distal interphalangeal joint. Based upon our literature review and imaging studies we have defined precisely Cleland’s ligaments, the oblique proximal septum, Grayson’s ligaments, the dorsal plate, and the interosseous ligaments of the distal interphalangeal joint.

Intramuscular fat is present in cervical multifidus but not soleus in patients with chronic whiplash associated disorders

The presence of intramuscular fat (IMF) in the cervical spine muscles of patients with whiplash associated disorders (WAD) has been consistently found. The mechanisms underlying IMF are not clear but preliminary evidence implicates a relationship with stress system responses. We hypothesised that if systemic stress system responses do play a role then IMF would be present in muscles remote to the cervical spine. We aimed to investigate if IMF are present in muscle tissue remote (soleus) to the cervical spine in people with chronic WAD. A secondary aim was to investigate associations between IMF and posttraumatic stress symptom levels. Forty-three people with chronic WAD (25 female) and 16 asymptomatic control participants (11 female) participated. Measures of pain, disability and posttraumatic stress symptoms were collected from the WAD participants. Both groups underwent MRI measures of IMF in cervical multifidus and the right soleus muscle. There was significantly greater IMF in cervical multifidus in patients with WAD and moderate/severe disability compared to controls (p = 0.009). There was no difference in multifidus IMF between the mild and moderate/severe disability WAD groups (p = 0.64), or the control and mild WAD groups (p = 0.21). IMF in the right soleus was not different between the groups (p = 0.47). In the WAD group, we found no correlation between PDS symptoms and cervical multifidus IMF or between PDS symptoms and soleus IMF. Global differences in IMF are not a feature of chronic WAD, with differences in IMF limited to the cervical spine musculature. While the mechanisms for the development of IMF in the cervical spine following whiplash injury remain unclear, our data indicate that local factors more likely contribute to these differences.

Shear wave elastography of the cervical arteries: A novel approach to the assessment of cervical arterial wall stiffness. An investigation of psychometric properties and intra-rater reliability

BACKGROUND Cervical arterial dissection, can occur spontaneously and is a rare but catastrophic adverse event associated with neck manipulation. Pathophysiology involves altered integrity of the arterial wall increasing its vulnerability to minor trauma. Those at risk are difficult to detect. Previous screening investigated blood flow but altered mechanical properties as stiffness of cervical arterial wall could provide a more valid indication of arterial integrity or even early dissection. OBJECTIVES To investigate suitability and intra-rater reliability of shear wave ultrasound elastography to measure mechanical properties of the cervical arterial wall. Suitability was assessed by ability to track arteries along their length and measurement accuracy. DESIGN Observational and intra-rater reliability study. METHODS Internal carotid (ICA) and vertebral arteries (VA) of healthy participants were examined with shear wave elastography. Shear wave velocity (m/s) indicative of wall stiffness was measured with the head in the neutral position: proximally (C3-4) and distally (C1-2) where injuries have been more commonly reported. Proximal measures were repeated to assess intra-rater reliability. RESULTS Thirty healthy participants (13 female), mean age of 29 (±12.8) years were imaged. Mean VA wall stiffness (3.4 m/s) was greater than ICA (2.3 m/s) (p < 0.000). Intra-rater reliability for ICA was ICC 0.81 (CI 0.52 to 0.92) and for VA ICC 0.76 (CI 0.38 to 0.9). Standard error of measurement was 0.16 for ICA and 0.34 for VA. CONCLUSIONS Shear wave ultrasound elastography appears a suitable and reliable method to measure cervical arterial wall stiffness, justifying further research into its use for screening arterial integrity.

Anterior temporal cortex activation during generation of novel category associates in schizophrenia

This journal suppl. entitled: Twelfth Annual Meeting of the Organization for Human Brain Mapping, Florence, Italy, 11–15 June 2006