Is It Possible to Perform Fifth Carpometacarpal Joint Arthroscopy? Cadaveric Study on Its Feasibility, Safety, and Potential Hazards in Portal Creation.

Background Fifth carpometacarpal joint (CMCJ) fracture dislocation is a relatively rare injury and most will require operative treatment because of its unstable nature. Improper reduction and fixation lead to joint surface destruction, pain, and reduced grasping power. Intra-articular fragment reduction is often obscured by dorsally displaced ulnar fragment. Therefore, fifth CMCJ arthroscopy can be advantageous in assisting intra-articular fragment reduction. However, there is no detailed description of the portal landmarks or portals' relationship with adjacent important structures in the literature. Purposes To explore the feasibility and safety of fifth CMCJ arthroscopy, locations of the portals are examined in cadaveric hand specimens. Their proximity to important anatomical structures such as dorsal cutaneous branch of ulnar nerve (DCBUN), ring finger and little finger extensor digitorum communis (EDC), and extensor digiti minimi (EDM) is measured. Methods Fifth CMCJ arthroscopy is performed on 11 cadaveric hand specimens by specialist-level surgeon. The portals are marked and portal positions are further confirmed under the fluoroscopy. Then the cadaveric specimens were undergone anatomical dissection by specialist-level surgeon. During dissection, the spatial relationship between the portal positions and DCBUN, EDC to ring finger and little finger, and EDM is identified. The distance between the portals and the above important structures was measured in millimeters. Results DCBUN was consistently found between fourth metacarpohamate (4-MH) and fifth metacarpohamate (5-MH) portals, with it being closer to the latter (mean distance, 2.03 mm; range, 0-4.43 mm; standard deviation [SD], 1.09 mm). The closest tendon for 4-MH portal is ring finger EDC (mean distance, 2.65 mm; range, 0-5.89 mm; SD, 1.78 mm), while 5-MH portal and accessory portal were closest to EDC (mean distance, 1.88 mm; range, 0-3.69 mm; SD, 1.25 mm) and EDM (mean distance, 7.79 mm; range, 6.63-10.72 mm; SD, 1.49 mm), respectively. During the process of specimen dissection, we found no damage to the above structures after portal introduction. Conclusion The above findings support the use of fifth CMCJ arthroscopy, which can be used for assisted reduction in fifth metacarpal base fracture dislocation and hamate body fracture. Gentle soft tissue spreading technique during portal creation prevents injury to the important structure surrounding the portals. Level of evidence This is a Level V study.

Using Ultrasound to Screen for Scoliosis to Reduce Unnecessary Radiographic Radiation: A Prospective Diagnostic Accuracy Study on 442 Schoolchildren.

Scoliosis screening is important for timely initiation of brace treatment to mitigate curve progression in skeletally immature children and adolescents. School scoliosis screening programs in Hong Kong follow the protocol of referring children screened positive with a scoliometer and Moiré topography for confirmatory standard radiography. Despite being highly sensitive (88%) in detecting those who require specialist referral, the screening program was found to have a false-positive rate >50%, which could lead to unnecessary X-ray radiation. Radiation-free ultrasound has been reported to be valid and reliable for quantitative assessment of curve severity in scoliosis patients. The aim of this prospective diagnostic accuracy study was to determine the accuracy of ultrasound in determining the threshold of referral that requires X-ray for children screened positive with the scoliometer and Moiré topography. Our study recruited 442 schoolchildren with a mean Cobb angle of 14.0 ± 6.6°. The sensitivity and specificity of ultrasound in predicting the correct referral status, confirmed by X-ray, were 92.3% and 51.6%, with positive and negative predictive values of 29.0% and 96.9%, respectively. Receiver operating characteristic curve analysis revealed area under the curve values of 0.735 for ultrasound alone and 0.832 for ultrasound in combination with measurement of angle of trunk rotation. The finding supports the accuracy of using ultrasound to determine referral status, which could result in a >50% reduction of unnecessary radiation for children undergoing scoliosis screening.

A novel radiographic classification of severe spinal curvatures exceeding 100°: the Omega (Ω), gamma (γ) and alpha (α) deformities.

PURPOSE: For spine curvatures with Cobb angles > 100°, curve classification and characterization become more difficult with conventional radiographs. 3-D computerized axial tomography scans add relevant information to categorize and describe a new classification to aid preoperative assessment in communication and patient evaluation. The purpose of this study is to describe a radiographic classification system of curves exceeding 100°. METHODS: A consecutive series of patients with curves exceeding 100° underwent a full spine radiographic review using conventional radiographs and 3-D CT. A descriptive analysis was performed to categorize curves into 4 main types (1, 2, 3 and 4) and 6 subtypes (1C, 1S, 1CS, 2P, 2D and 2PD) based on the location of the Cobb angle of the major scoliotic and kyphotic deformity as well as the location of the upper/lower end vertebra relative to the apical vertebra. RESULTS: A total of 98 patients met the inclusion criteria. There were 51 males and 47 females with an average age of 17.8 ± 4.5 years. The diagnosis included idiopathic (48); congenital (24); neuromuscular (4); and neurofibromatosis (2). The mean major coronal and sagittal Cobb (kyphosis) were 131.2° ± 23.4° and 154 ± 45.6, respectively. The classification scheme yielded 4 main types (1, 2, 3 and 4) and 6 subtypes under types 1 and 2 (1C, 1S, 1CS, 2P, 2D and 2PD). CONCLUSIONS: Our study describes a novel method of classifying severe spinal curvatures exceeding 100° using erect AP/lateral radiographs and 3-D CT reconstructive images. We hope that the descriptive analysis and classification will expand our understanding of these complex deformities. These slides can be retrieved under Electronic Supplementary Material.

The association of lumbar intervertebral disc calcification on plain radiographs with the UTE Disc Sign on MRI.

PURPOSE: The pathogenesis and the clinical impact of disc calcification are not well known. Utilizing ultra-short time-to-echo (UTE) magnetic resonance imaging, the UTE Disc Sign (UDS) (i.e., hypo/hyper-intense disc band) was developed and found to be more significantly related to pain and disability than the conventional T2-weighted (T2W) MRI. It has been hypothesized that the UDS may represent mineralized deposits in the disc. The following study addressed the relationship between disc calcification on plain radiographs to that of the UDS on MRI. METHODS: A cross-sectional study was performed on 106 Southern Chinese subjects (50% male; mean age 52.3 years). Standing lateral plain radiographs as well as T2W and UTE MRI of L1-S1 (n = 530 discs) were performed of all subjects. Lateral radiographs were used to localize disc calcification of the lumbar spine, T2W MRI was utilized to assess disc degeneration based on a defined grading scheme, and the UTE MRI was implemented to detect the UDS (hyper- or hypo-intense band across a disc). Disc degeneration and UDS scores were summed to represent cumulative scores. Subject demographics and disability profiles (Oswestry Disability Index: ODI) were obtained. RESULTS: Disc calcification on plain radiographs was observed in 33.9% of subjects (55.5% males; mean age 54.3 years), whereas UDS was noted in 40.5% of subjects (51.1% males; mean age 55.0 years). Of these subjects, 66.6% calcification and 74.4% UDS occurred at the three lowest lumbar levels, while multilevel calcification and UDS involved 19.4 and 39.5%, respectively. 72.2% of subjects with plain radiographic disc calcification had corresponding UDS on UTE MRI (p < 0.001). Multilevel disc calcification on plain radiographs was associated with multilevel UDS (71.4%, p < 0.001). Both the number of calcified disc levels on plain radiographs and the number of UDS levels were also significantly and positively correlated with each other (r = 0.58, p < 0.001). Subjects with disc calcification and positive UDS as well as individuals with increased disc degeneration scores on T2 W MRI were significantly older (p < 0.05). The cumulative UDS score on UTE MRI significantly correlated with worse ODI scores (r = 0.31; p = 0.001), whereas cumulative disc calcification scores on plain radiographs did not (r = 0.15; p = 0.19). CONCLUSIONS: This is the first study to compare the UDS on UTE MRI with disc calcification on plain radiographs. Disc calcification was correlated with the UDS on UTE, suggesting that the UDS may represent disc calcification. However, UTE MRI appears to be a more sensitive imaging modality in identifying subtle and unique disc changes that may not be revealed on plain radiographs or conventional MRI. This disconnect may rationalize the significant correlation of UTE with disability in comparison with the conventional imaging, further stressing its potential clinical importance.

The UTE Disc Sign on MRI: A Novel Imaging Biomarker Associated With Degenerative Spine Changes, Low Back Pain, and Disability.

STUDY DESIGN: Cross-sectional. OBJECTIVE: To assess the distribution of the ultra-short time-to-echo (UTE) disc sign (UDS) and its association with disc degeneration, other magnetic resonance imaging (MRI) phenotypes, pain, and disability profiles. SUMMARY OF BACKGROUND DATA: Disc degeneration has been conventionally assessed by T2-weighted (T2W) signal intensity on MRI; however, its clinical utility has been questionable. UTE MRI assesses short T2 components. The authors have identified a new imaging biomarker on UTE-the UDS. METHODS: One hundred eight subjects were recruited. T2W MRI assessed disc degeneration and other phenotypes, and T1-rho MRI values represented quantitative proteoglycan disc profiles of L1-S1. UDS was detected on UTE (i.e., hyper-/hypointense disc band). A UDS score (cumulative number of UDS levels) and T2W summated lumbar degenerated scores (cumulative disc degeneration score) were assessed. Subject demographics, chronic low back pain (LBP), and disability profiles (Oswestry Disability Index: ODI) were obtained. RESULTS: UDS was noted in 39.8% subjects, 61.4% occurred at the lower lumbar spine and 39.5% had multilevel UDS. UDS subjects had significantly greater severity and extent of disc degeneration, and Modic changes (P < 0.05). By disc levels, a higher prevalence of disc degeneration/displacement, Modic changes, and spondylolisthesis were noted in UDS discs than non-UDS discs (P < 0.05). T1-rho values were also lower in UDS discs (P = 0.022). The majority of UDS could not be detected on T2W. The UDS score significantly correlated with worse ODI scores (r = 0.311; P = 0.001), whereas T2W cumulative disc degeneration score did not (r = 0.13; P = 0.19). LBP subjects exhibited more multilevel UDS (P < 0.015) but not on T2W MRI (P = 0.53). The UDS score was significantly related to LBP (P = 0.009), whereas T2W cumulative disc degeneration score was not (P = 0.127). CONCLUSION: This is the first study to report "UDS" in humans. UDS is a novel imaging biomarker that is highly associated with degenerative spine changes, chronic LBP, and disability than conventional T2W MRI. LEVEL OF EVIDENCE: 2.

Computational modeling of bone density profiles in response to gait: a subject-specific approach.

The goal of this study is to explore the potential of computational growth models to predict bone density profiles in the proximal tibia in response to gait-induced loading. From a modeling point of view, we design a finite element-based computational algorithm using the theory of open system thermodynamics. In this algorithm, the biological problem, the balance of mass, is solved locally on the integration point level, while the mechanical problem, the balance of linear momentum, is solved globally on the node point level. Specifically, the local bone mineral density is treated as an internal variable, which is allowed to change in response to mechanical loading. From an experimental point of view, we perform a subject-specific gait analysis to identify the relevant forces during walking using an inverse dynamics approach. These forces are directly applied as loads in the finite element simulation. To validate the model, we take a Dual-Energy X-ray Absorptiometry scan of the subject's right knee from which we create a geometric model of the proximal tibia. For qualitative validation, we compare the computationally predicted density profiles to the bone mineral density extracted from this scan. For quantitative validation, we adopt the region of interest method and determine the density values at fourteen discrete locations using standard and custom-designed image analysis tools. Qualitatively, our two- and three-dimensional density predictions are in excellent agreement with the experimental measurements. Quantitatively, errors are less than 3% for the two-dimensional analysis and less than 10% for the three-dimensional analysis. The proposed approach has the potential to ultimately improve the long-term success of possible treatment options for chronic diseases such as osteoarthritis on a patient-specific basis by accurately addressing the complex interactions between ambulatory loads and tissue changes.