Iatrogenic "overshoot" nerve injuries: imaging features.

OBJECTIVE: Describe features of iatrogenic "overshoot" nerve injuries on ultrasound and MRI, which occur when an instrument passes through the bone and injures the nerve after it penetrates the opposite cortex. MATERIALS AND METHODS: After a keyword search of the radiology database at a tertiary care orthopedic hospital from January 2016 to December 2022, those fulfilling the inclusion criteria of (1) instrumentation through the bone during surgery, (2) acute neuropathy immediately after surgery, (3) nerve injury confirmed on electrodiagnostics, and (4) imaging consistent with overshoot nerve injury were included. Imaging studies were retrospectively evaluated to determine primary and secondary signs of an overshoot nerve injury. RESULTS: Six patients (3 females, mean age 26.7 (range 10-49) years) had nerve injury fitting the mechanism of injury: 3 injuries to the radial nerve during fixation of distal humerus fractures, 1 tibial nerve and 1 superficial peroneal nerve injury during fixation of tibial fractures, and 1 posterior interosseous nerve injury during biceps tendon repair. Ultrasounds were performed in all while 4 also had MRI. Secondary signs included (1) cortical defect adjacent to injured nerve (n=2); (2) scar extending from bone to injured nerve (n=2); (3) screw tip pointing to injured nerve (n=1, 4) tract in bone on MRI from previous instrumentation pointing to injured nerve (n=2). CONCLUSION: In addition to primary signs such as laceration or neuroma, secondary signs of "overshoot" nerve injury include cortical defect, scar extending to nerve, screw tip pointing to nerve, and linear tract in the bone on MRI.

Ultrasound of the distal biceps brachii tendon using four approaches: reproducibility and reader preference.

OBJECTIVES: To determine which sonographic appearance of the distal biceps brachii tendon (DBBT) is preferred by readers, and if images obtained by two different operators are reproducible. METHODS: We performed an IRB-approved prospective sonographic evaluation of the DBBT in 50 healthy elbows using four different approaches (anterior, lateral, medial, posterior) performed by two operators. Five musculoskeletal radiologists independently reviewed the images, and ranked the four approaches based on overall appearance of echogenicity of the tendon, visualized length, and visualization of the insertion. RESULTS: The medial approach was preferred in 79.6% of elbows, anterior in 17.6%, lateral in 2.8%, and the posterior approach was never preferred. The difference was statistically significant (P < 0.001). Kappa values for the five readers were 0.61 to 0.8 for choosing the images produced by the medial approach. CONCLUSION: The appearance of the DBBT using the medial approach is preferred by readers and is reproducible between different operators.

Outcomes of Microneurolysis of Hourglass Constrictions in Chronic Neuralgic Amyotrophy.

PURPOSE: Wide variability in the recovery of patients affected by neuralgic amyotrophy (NA) is recognized, with up to 30% experiencing residual motor deficits. Using magnetic resonance imaging and ultrasound (US), we identified hourglass constrictions (HGCs) in all affected nerves of patients with chronic motor paralysis from NA. We hypothesized that chronic NA patients undergoing microsurgical epineurolysis and perineurolysis of constrictions would experience greater recovery compared with patients managed nonsurgically. METHODS: We treated 24 patients with chronic motor palsy from NA and HGCs identified on magnetic resonance imaging and US either with microsurgical epineurolysis and perineurolysis of HGCs (11 of 24) or nonsurgically (13 of 24). Muscle strength (both groups) and electrodiagnostic testing (EDX) (operative group) was performed before and after surgery. Preoperative EDX confirmed muscle denervation in the distribution of affected nerve(s). All patients met criteria for microneurolysis: 12 months without improvement since onset or failure of clinical and EDX improvement after 6 months documented by 3 successive examinations, each at least 6 weeks apart. RESULTS: Mean time from onset to surgery was 12.5 ± 4.0 months. Average time to most recent post-onset follow-up occurred at 27.3 months (range, 18-42 months; 15 nerves). Average time to latest follow-up among nonsurgical patients was 33.6 months (range, 18-108 months; 16 nerves). Constrictions involved individual fascicular groups (FCs) of the median nerve and the suprascapular, axillary and radial nerves proper (HGCs). Nine of 11 operative patients experienced clinical recovery compared with 3 of 13 nonsurgical patients. EMG revealed significant motor unit recovery from axonal regeneration in the operative group. CONCLUSIONS: Microsurgical epineurolysis and perineurolysis of FCs and HGCs was associated with significantly improved clinical and nerve regeneration at an average follow-up of 14.8 months compared with nonsurgical management. We recommend microneurolysis of HGCs and FCs as a treatment option for patients with chronic NA who have failed to improve with nonsurgical treatment. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Surgical Decision Making for Mild-to-Moderate Cubital Tunnel Syndrome.

Purpose: The management of ulnar neuropathy remains unclear as there are neither consensus guidelines nor compelling data available to inform optimal treatment. Identifying patients in the mild-to-moderate group that would benefit most from surgery is challenging as their symptoms can be subtle and less debilitating. This study investigated predictors of surgical intervention among patients presenting with McGowan mild or moderate cubital tunnel syndrome (CuTS). Methods: This is an institutional review board-approved study. Patients evaluated from March 2016 to July 2022 were included if they were diagnosed with McGowan mild or moderate CuTS and underwent concurrent electrodiagnostic and ultrasound evaluations. Patient demographics, symptom presentation, and clinical and diagnostic test findings were analyzed. Variables were analyzed using Student t test, Mann-Whitney U test, or Pearson's chi-square test. Multivariable logistic regression was used to assess the association of covariates and surgery. Results: Seventy-three patients and 103 elbows were identified. The mean age and body mass index were 51 years and 26.9, respectively. Most patients were men, right-handed, and unilaterally symptomatic in the dominant hand. Twenty-six elbows were surgically treated. Bivariable analyses by surgical treatment showed that patients who underwent surgery more often had positive electrodiagnostic findings including motor nerve conduction velocity <50 m/s and a >10 m/s conduction velocity difference across the forearm compared with elbow. Fifty-nine cases were categorized as electrodiagnostically normal. Of the electrodiagnostically normal cases, 29 had positive findings of CuTS on ultrasound. Logistic regression model showed that electrodiagnostically severe cases had 3.7 times higher odds of being surgically treated than normal counterparts (adjusted odds ratio, 3.7; 95% CI, 1.11-12.6; P = .03). Conclusions: Not many differences in objective findings identify patients who should receive operative treatment. In addition to test results, more subjective findings from patients such as patient-reported level of impairment may be able to bridge this gap in surgical decision making. Clinical relevance: This study contributes to treatment decision making for mild and moderate CuTS.

No Difference in Reintervention at 1-Year Between Ultrasound-Guided versus Blind Dorsal Carpal Ganglion Aspiration.

Purpose: The purpose of this retrospective comparative study was to compare the efficacy of dorsal carpal ganglion aspiration in patients who underwent either "blind" (using surface anatomy alone) or ultrasound-guided (US-guided) aspiration. Methods: Outcome measures were conducted during the coronavirus disease 2019 pandemic via telephone for a minimum of 12 months after aspiration, with efficacy defined by reintervention with either repeat aspiration or surgical excision. Results: Data are reported for 141 patients (46 blind; 95 US-guided) at an average of 28 months (range, 12-55 months) from aspiration. Reintervention was not significantly different based on the mode of aspiration-26% and 24% for blind aspiration and US-guided, respectively. Patient-perceived recurrence was higher at 65% for the entire cohort. Patients who received steroid injection at the time of aspiration perceived lower rates of recurrence-44% versus 77% for patients who received a steroid injection and patients who did not, respectively. Conclusions: This study found no significant difference between blind or US-guided aspiration in reintervention at a minimum of 1-year follow-up. Patients who received steroids at the time of aspiration perceived lower rates of recurrence. Type of study/level of evidence: Therapeutic III.

Ultrasound Shear Wave Elastography Quantitatively Assesses Tension Changes of Supraspinous/Interspinous Ligament Complex Under Varied Loads.

BACKGROUND: Although interspinous and supraspinous ligaments of the lumbar spine are thought to contribute to spinal stability, little is known about their dynamic biomechanics. We demonstrate that shear wave elastography (SWE) offers a novel technique to noninvasively and quantitatively evaluate posterior spinous ligament complex functional loading and stiffness in different physiologic positions. METHODS: We performed SWE and measured the length of the interspinous/supraspinous ligament complex in cadaveric torsos (N = 5), isolated ligaments (N = 10), and healthy volunteers (N = 9) to obtain length and shear wave velocity measurements. For cadavers and volunteers, SWE was utilized in 2 lumbar positions: lumbar spine flexion and extension. In addition, SWE was performed on isolated ligaments undergoing uniaxial tension to correlate shear wave velocities with experienced load. RESULTS: Average shear wave velocity in cadaveric supraspinous/interspinous ligament complexes increased for lumbar levels (23%-43%) and most thoracic levels (0%-50%). This corresponded to an average increase in interspinous distance from extension to flexion for the lumbar spine (19%-63%) and thoracic spine (3%-8%). Volunteer spines also demonstrated an average increase in shear wave velocity from extension to flexion for both the lumbar spine (195% at L2-L3 to 200% at L4-L5) and thoracic spine (31% at T10-T11). There was an average increase in interspinous distance from extension to flexion for the lumbar spine (93% at L2-L3 to 127% at L4-L5) and thoracic spine (11% at T10-T11). In isolated ligaments, there was a positive correlation between applied tensile load and average shear wave velocity. CONCLUSION: This study creates a foundation to apply SWE as a noninvasive tool for assessing the mechanical stiffness of posterior ligamentous structures and has potential applications in augmenting or evaluating these ligaments in patients with spine pathology. CLINICAL RELEVANCE: The interspinous and supraspinous ligaments are critical soft tissue supports of the posterior lumbar spine. Disruption of these structures is thought to have a negative impact on spinal stability in trauma and spine deformities.

Short-term Results of Magnetic Resonance Imaging after Ankle Distraction Arthroplasty.

BACKGROUND: Ankle distraction arthroplasty has emerged as an alternative treatment for ankle arthritis. There are few reports on the magnetic resonance imaging (MRI) findings after distraction arthroplasty. This study sought to determine whether there are positive changes on MRI after ankle distraction and improvements on X-ray. Additionally, patient-reported outcomes and joint range of motion (ROM) after ankle distraction are described. MATERIALS AND METHODS: Thirty-two patients (mean age 49 years) who underwent ankle distraction had pre-operative and one-year postoperative MRIs, which were graded using a modified whole-organ magnetic resonance imaging score (WORMS). Ankle joint space and ROM were measured. A non-validated three-item questionnaire was administered to assess functional outcomes. RESULTS: Although the anterior quadrant of the ankle showed a trend to improvement in cartilage morphology on the postoperative MRI, the WORMS did not demonstrate a significant difference in any of its subcategories. While reduction in joint osteophytes was observed and maintained short term, this was mainly due to resection intraoperatively. X-rays revealed a significant increase in joint space, and there was a significant increase in ankle dorsiflexion. Eight-seven percent of the patients were satisfied with their functional outcome. CONCLUSION: At short-term follow-up, MRI scores after ankle distraction arthroplasty did not demonstrate significant improvement despite positive changes on X-ray and improved clinical outcomes and ankle ROM. Further study on larger patient numbers with longer follow-up is required. LEVEL OF EVIDENCE: IV, Case Series. HOW TO CITE THIS ARTICLE: Haleem AM, Galal S, Nwawka OK, et al. Short-term Results of Magnetic Resonance Imaging after Ankle Distraction Arthroplasty. Strategies Trauma Limb Reconstr 2020;15(3):157-162.

Comparison of polyp size and volume at CT colonography: implications for follow-up CT colonography.

OBJECTIVE: The purpose of this study was to evaluate the reliability of polyp measurements at CT colonography and the factors that affect the measurements. MATERIALS AND METHODS: Fifty colonoscopically proven cases of polyps 6 mm in diameter or larger were analyzed by two observers who measured each polyp in supine and prone views. Manual measurements of 2D volume by summation of areas, 2D maximum diameter, and 3D maximum diameter and automated measurements of 3D maximum diameter and volume were recorded for each observer and were repeated for one of the observers. Intraobserver and interobserver agreement was calculated. Analysis was performed to determine the measurement parameter that correlated most with summation-of-areas volume. Supine and prone measurements as a surrogate for tracking change in polyp size over time were analyzed to determine the measurement parameter with the least variation. RESULTS: Maximum diameter measured manually on 3D images had the highest correlation with summation-of-areas volume. Manual summation-of-areas volume was found to have the least variation between supine and prone measurements. CONCLUSION: Linear polyp measurement in the 3D endoluminal view appears to be the most reliable parameter for use in the decision to excise a polyp according to current guidelines. In our study, manual calculation of volume with summation of areas was found to be the most reliable measurement parameter for observing polyp growth over serial examinations. High reliability of polyp measurements is essential for adequate assessment of change in polyp size over serial examinations because many patients with intermediate-size polyps are expected to choose surveillance.