Clinical utilization of shear wave elastography in the musculoskeletal system.

Shear wave elastography (SWE) is an emerging technology that provides information about the inherent elasticity of tissues by producing an acoustic radiofrequency force impulse, sometimes called an acoustic wind, which generates transversely-oriented shear waves that propagate through the surrounding tissue and provide biomechanical information about tissue quality. Although SWE has the potential to revolutionize bone and joint imaging, its clinical application has been hindered by technical and artifactual challenges. Many of the stumbling blocks encountered during musculoskeletal SWE imaging are readily recognizable and can be overcome, but progressive advances in technology and a better understanding of image acquisition are required before SWE can reliably be used in musculoskeletal imaging

Clinical utilization of shear wave elastography in the musculoskeletal system

Shear wave elastography (SWE) is an emerging technology that provides information about the inherent elasticity of tissues by producing an acoustic radiofrequency force impulse, sometimes called an acoustic wind, which generates transversely-oriented shear waves that propagate through the surrounding tissue and provide biomechanical information about tissue quality. Although SWE has the potential to revolutionize bone and joint imaging, its clinical application has been hindered by technical and artifactual challenges. Many of the stumbling blocks encountered during musculoskeletal SWE imaging are readily recognizable and can be overcome, but progressive advances in technology and a better understanding of image acquisition are required before SWE can reliably be used in musculoskeletal imaging

Measuring Three-Dimensional Thorax Motion Via Biplane Radiographic Imaging: Technique and Preliminary Results.

Measures of scapulothoracic motion are dependent on accurate imaging of the scapula and thorax. Advanced radiographic techniques can provide accurate measures of scapular motion, but the limited 3D imaging volume of these techniques often precludes measurement of thorax motion. To overcome this, a thorax coordinate system was defined based on the position of rib pairs and then compared to a conventional sternum/spine-based thorax coordinate system. Alignment of the rib-based coordinate system was dependent on the rib pairs used, with the rib3:rib4 pairing aligned to within 4.4 ± 2.1 deg of the conventional thorax coordinate system

Association Between Years of Competition and Shoulder Function in Collegiate Swimmers

BACKGROUND: Shoulder injuries are common among competitive swimmers, and the progression of shoulder pathology is not well understood. The objective of this study was to assess the extent to which years of competitive swim training were associated with physical properties of the supraspinatus muscle and tendon, shoulder strength, and self-reported assessments of shoulder pain and function. HYPOTHESIS: Increasing years of competition will be associated with declining physical properties of the supraspinatus muscle/tendon and declining self-reported assessments of pain and function. STUDY DESIGN: Descriptive epidemiology study. LEVEL OF EVIDENCE: Level 4. METHODS: After institutional approval, 18 collegiate female swimmers enrolled in the study. For each swimmer, supraspinatus tendon thickness was measured; tendinosis was assessed using ultrasound imaging, supraspinatus muscle shear wave velocity was assessed using shear wave elastography, isometric shoulder strength was measured using a Biodex system, and self-reported assessments of pain/function were assessed using the Western Ontario Rotator Cuff (WORC) score. All subjects were tested before the start of the collegiate swim season. Linear regression was used to assess the association between years of competition and the outcome measures. RESULTS: Years of participation was positively associated with tendon thickness ( P = 0.01) and negatively associated with shear wave velocity ( P = 0.04) and WORC score ( P \u3c 0.01). Shoulder strength was not associated with years of participation ( P \u3e 0.39). CONCLUSION: Long-term competitive swim training is associated with declining measures of supraspinatus muscle/tendon properties and self-reported measures of pain and function. Although specific injury mechanisms are still not fully understood, these findings lend additional insight into the development of rotator cuff pathology in swimmers. CLINICAL RELEVANCE: Lengthy swimming careers may lead to a chronic condition of reduced mechanical properties in the supraspinatus muscle and tendon, thereby increasing the likelihood of rotator cuff pathology

Effect of Arthroscopic Stabilization on In Vivo Glenohumeral Joint Motion and Clinical Outcomes in Patients With Anterior Instability.

BACKGROUND: Glenohumeral joint (GHJ) dislocations are common, and the resulting shoulder instability is often treated with arthroscopic stabilization. These procedures result in favorable clinical outcomes, but abnormal GHJ motion may persist, which may place patients at risk for developing osteoarthritis. However, the effects of shoulder instability and arthroscopic stabilization on GHJ motion are not well understood. HYPOTHESIS: GHJ motion is significantly influenced by anterior instability and arthroscopic stabilization, but postsurgical measures of GHJ motion are not different from those of control subjects. STUDY DESIGN: Controlled laboratory study. METHODS: In vivo GHJ motion was measured by applying a computed tomographic model-based tracking technique to biplane radiographic images acquired during an apprehension test in healthy control subjects (n = 11) and anterior instability patients (n = 11). Patients were tested before surgery and at 6 months after surgery. Control subjects were tested once. Shoulder strength, active range of motion (ROM), and the Western Ontario Shoulder Instability (WOSI) index were also measured. RESULTS: Before surgery, the humerus of the instability patients during the apprehension test was located significantly more anteriorly on the glenoid (7.9% of glenoid width; 2.1 mm) compared with that of the controls (P = .03), but arthroscopic stabilization moved this joint contact location posteriorly on the glenoid (4.7% of glenoid width; 1.1 mm; P = .03). After surgery, GHJ excursion during the apprehension test was significantly lower (14.7% of glenoid width; 3.6 mm) compared with presurgical values (19.4% of glenoid width; 4.7 mm; P = .01) and with that of the controls (22.4% of glenoid width; 5.7 mm; P = .01). The external and internal rotation strength of patients was significantly lower than that of the controls before surgery (P \u3c .05), but differences in strength did not persist after surgery (P \u3e .17). External rotation ROM in patients was significantly lower than that in control subjects both before and after arthroscopic stabilization (P \u3c .01). The WOSI score improved significantly, from 48.3 ± 13.1 presurgery to 86.3 ± 16.5 after surgery (P = .0002). CONCLUSION: In patients with anterior instability, arthroscopic stabilization significantly improves measures of strength, ROM, and clinical outcome. However, GHJ excursion is not fully restored to levels seen in the control subjects. CLINICAL RELEVANCE: Although arthroscopic stabilization satisfactorily restores most clinical outcome measures, GHJ excursion and external rotation ROM remain compromised compared with healthy control subjects and may contribute to the development of osteoarthritis in patients with anterior instability

Cervical nerve root to foraminal size ratio correlates with post-surgical patient-reported outcomes

INTRODUCTION: Changes in cervical neural foraminal (CNF) dimensions are considered a key factor in development of cervical radiculopathy due to their role in nerve root compression. However, cadaveric and in vivo studies indicate considerable variation in the size of nerve roots as well [1, 2], which, intuitively, should affect their risk of being compressed by the foramina. Recent studies reported a small but significant difference in nerve size between asymptomatic and symptomatic patients [3]; however, the relationship of nerve root size with clinical outcomes has not been studied in patients who have received surgical treatment of degenerative disease in their cervical spine and are at a time point significant for development of adjacent segment disease. This pilot study examined such relationships. We hypothesize that nerve root size (alone or relative to foraminal size) is associated with clinical symptoms. METHODS: Under local IRB approval, clinical MRI images obtained, using a 3D BTFE sequence (1.5 T, 0.65x0.65x1.5 mm voxel size) from 11 patients (7F, 35-75 years; 4M, 44-66 years; a convenience group) who had previously underwent either arthroplasty with an artificial disc (n=1) or anterior cervical discectomy and fusion (n=10) at the C5-6 level were used. At the time of imaging, average time post-surgery was 6.5 years (sd ±1.7 years). Resliced anterolateral views were prepared from axial images using multiplanar reconstruction (MPR) tools in Synedra View (v. 16.0.0.2, Innsbruck, Austria). Views were constructed parallel to and passing through the left and right nerve roots (approximately 50 degrees oblique to the sagittal plane) at C3-4, C4-5, C5-6 and C6-7 levels. Freehand selection tool was used to delineate the nerve and the foramen (Fig. 1). Foraminal area (FA) and width (FW), nerve root area (NA) and width (NW) and nerve root to foramen ratios of these variables (N/F.A and N/F.W) were calculated. All foraminal, nerve root and foramen to nerve root ratio variables measured within a patient were averaged over left and right sides and spine levels to obtain a single composite variable of each type for each patient. Each patient was assessed using the following validated patient reported outcome measures [4]: the visual analogue scale (VAS) for neck and arm pain, the modified Japanese Orthopedic Association (mJOA) score [5], the Neck Disability Index (NDI), and the EuroQol EQ-5D score. The VAS and NDI assess for pain and functional disability directly related to neck and arm symptoms (higher worse). The mJOA is a disease specific scale for assessing myelopathy (higher better) and the EQ-5D is a general health assessment (higher worse). The relationship between survey and image parameters were examined using correlation and regression analyses. For survey variables with a binary outcome, the correlations were examined using logistic regression. RESULTS: The average (±sd) composite NA, NW, N/F.A and N/F.W were 6.31 ± 0.72 mm2, 1.71 ± 0.14 mm, 0.103 ± 0.022 and 0.297 ± 0.044, respectively. No spine level was significantly more represented than others in composite variables. Increased overall NDI score was associated with decreased FW (R= -0.65, p\u3c0.05) and increased N/F.W (R= 0.68, p\u3c0.05) (Fig. 2). Increased FW was also associated with decreased scores in sections of NDI related to pain intensity (R= -0.88, p\u3c0.001), driving (R= -0.67, p\u3c0.04) and recreation (R= -0.75, p\u3c0.02) as well as neck and arm pain VAS (R= - 0.82, p\u3c0.004 and R= -0.81, p\u3c0.005, respectively), while N/F.W was associated with increased scores in sections of NDI related to pain intensity (R= 0.68, p\u3c0.05), reading (R= 0.74, p\u3c0.04), driving (R= 0.74, p\u3c0.03) and recreation (R= -0.75, p\u3c0.02). Additionally, increased N/F.A was associated with increased neck pain VAS (R= 0.79, p\u3c0.02). None of the image variables were significantly associated with the overall EQ-5D scores. However, increased FW was associated with decreased usual activities subscore (R= -0.76, p\u3c0.02) and increased N/F.A was associated with increased pain and discom ort subscore (R= 0.72, p\u3c0.03) of the survey. None of the image variables were significantly associated with the overall mJOA scores, except for a marginally significant positive correlation for FW (p=0.055). However, increased FW was associated with increased leg numbness subscore (R= 0.73, p\u3c0.02), increased NA was associated with increased urination subscore (R= 0.71, p\u3c0.04) and increased N/F.W was associated with decreased trunk numbness subscore (R= -0.67, p\u3c0.05) of the survey. DISCUSSION: To our knowledge, this is the first data on nerve root dimensions obtained over 6 years after cervical spine surgery, offering a connection between clinical outcomes and dimensions of nerve roots relative to foramina. The post-operative time of the examinations is significant in that it represents the onset of adjacent segment disease after initial surgery [6]. Our nerve root width and area measurements are generally in agreement with those of others measured in vivo via ultrasonography [2, 3, 7, 8] or from cadavers via dissection [1, 9]. The size of nerve roots relative to foramina were associated with worsening overall NDI and specific pain subscores of NDI and EQ-5D surveys. As expected, this is partially attributable to smaller foramina alone. However, foraminal size did not correlate with all variables that nerve to foramen ratio variables did, indicating that nerve size has value independently from foraminal size. Width variables were associated with survey variables more frequently than did area variables. While it is possible that foraminal and nerve root width are indeed more important than their respective height or area, this may be a result of anisotropic resolution in the images providing a higher resolution in the width direction. When nerve size was considered alone, greater nerve width was associated with worse personal care, driving and work subscores of the NDI survey, consistent with the idea that a larger nerve may be associated with an increased risk of compression. Interestingly, however, greater nerve area was associated with a better bladder function in the mJOA survey. This, and correlations to subscores such as leg numbness may be coincidental or indicative of underlying neurodegenerative disease or response to injury [10] rather than a causal association to mechanical stress. These results are considered preliminary due to the low number of patients examined, particularly those who are significantly symptomatic. Also, the measurements could not be performed at all locations of the cervical spine due to image artifacts caused by implants [11]. Future work is needed to further optimize imaging protocols for measurement of neuro-foraminal dimension variables and determine cut-off values for prediction of clinical outcomes in a prospective cohort. (Figure Presented)