Median and Digital Nerve In Situ Tension in the Hand.

Background: Digital nerves will experience tension under normal daily activities, and understanding the amount of tension experienced in these nerves relates directly to the necessary strength in nerve repairs. To begin quantification of tension, the tension borne by the median and digital nerves in cadaveric hands was quantified under conditions of finger hyperextension, nerve distraction, and finger flexion. Methods: Five cadaveric hands were mounted in a special fixture that allowed finger hyperextension and flexion and could apply known distractions while the tension borne by each digital nerve was measured. Sequential dissection exposed the digital nerves so that measurements of tension in the median, common, and proper digital nerves were conducted with finger hyperextension, nerve distraction, and finger flexion. Results: Metacarpophalangeal (MCP) hyperextension of 30° created mean nerve tensions up to 0.64 N, 5 mm of nerve distraction created mean nerve tensions up to 1.23 N, and 90° of MCP flexion relieved up to a mean of 1.18 N of nerve tension. Conclusions: In situ tension is present in the median and digital nerves with digital motion. Finger hyperextension and nerve distraction produce tension, whereas finger flexion reduces tension. Existing nerve repairs are strong enough to withstand in situ nerve tensions produced by reasonable digital motion if the original nerve length is present.

Physiologic widening of the medial clear space: What's normal?

BACKGROUND: Literature has validated the use of stress radiographs for evaluation of ankle stability. However, to our knowledge no study has reported the amount of physiological widening that occurs with manual external rotation stress test in uninjured ankles. The purpose of this study was to assess the amount of medial clear space widening that occurs with a manual external rotation stress test in uninjured ankles. METHODS: A cohort of adult patients undergoing operative fixation of unstable ankle fractures were prospectively enrolled to have their contralateral ankle undergo manual external rotation stress examination. Fluoroscopic images of the unaffected ankle were performed in the OR. A non-stressed mortise view and manual external rotation stress view were obtained with a standardized marker to correct for magnification differences. The images were de-identified, presented in a randomized order and reviewers who were blinded. Each reviewer measured the medial clear space. RESULTS: Thirty fluoroscopic images on fifteen patients were obtained. The mean medial clear space on the non-stressed mortise view was 3.1 mm (SD-0.69; Range 1.9 to 4.2, 95% CI [2.75, 3.45]) versus a mean of 3.2 mm (SD-0.71; Range 2.0 to 4.7, 95% CI [2.94, 3.66]) in the stressed mortise view group. Inter-rater reliability was excellent between all observers for medial clear space (ICC-0.88; CI [0.78, 0.94]). CONCLUSIONS: Our results support the previous literature and allow us to advocate for ankle fractures with >5 mm medial clear space after external rotational stress to be considered unstable. Additionally, ankles with a medial clear space between 4 and 5 mm, instability should be considered only if lateral shift is > 2 mm on stress examination. Our data shows that no physiologically healthy ankles widened beyond these established cut-offs before or after the manual external rotation stress.

Anatomy, Etiology, and Management of Scapular Winging.

Scapular winging is a painful and debilitating condition. The composite scapular motion of rotation, abduction, and tilting is necessary for proper shoulder function. Weakness or loss of scapular mechanics can lead to difficulties with elevation of the arm and lifting objects. The most common causes reported in the literature for scapular winging are dysfunction of the serratus anterior from long thoracic nerve injury causing medial winging or dysfunction of the trapezius from spinal accessory nerve injury causing lateral winging. Most reviews and teaching focus on these etiologies. However, acute traumatic tears of the serratus anterior, trapezius, and rhomboids off of the scapula are important and under-recognized causes of scapular winging and dysfunction. This article will review the relevant anatomy, etiology, clinical evaluation, diagnostic testing, and treatment of scapular winging. It will also discuss the differences in diagnosis and management between scapular winging arising from neurogenic causes and traumatic muscular detachment.

The Role of Computed Tomography in Surgical Planning for Trimalleolar Fracture. A Survey of OTA Members.

OBJECTIVE: Does the additional information provided by computed tomography (CT) alter surgeons' treatment plans for trimalleolar ankle fracture? DESIGN: Prospective. SETTING: Electronic survey. PATIENTS/PARTICIPANTS: Members of the OTA. INTERVENTION: Compare management of trimalleolar ankle fracture before and after CT. MAIN OUTCOME MEASUREMENTS: Compare types of fixation used, indication for fixation, and approach need for fixation before and after CT. RESULTS: Overall, OTA members' operative technique changed in 430 of the 1710 (25.1%) cases after review of the CT images. Of the 430 observations in which the operative technique was altered, the surgeon had initially stated that they would not have requested a CT in 51.2% incidences. When analyzing if CT affected whether or not operative fixation was indicated, a total of 16.3% responses changed. Surgeons were significantly more likely to change from no fixation to fixation (11.5%) than vice versa (4.8%) after reviewing CT imaging. A total of 17.8% of responses changed operative approach after reviewing the CT; 11.7% changed to open reduction internal fixation, whereas 6.1% changed away from open reduction internal fixation. CONCLUSION: A consensus on the ideal treatment of trimalleolar fractures remains elusive, evidenced by a high variation in treatment preference, both before and after CT review. Our results demonstrate with the additional information delineated on CT, a surgeons' operative plan, technique, and approach often change. With greater than 25% of respondents changing their treatment strategy after seeing CT imaging, radiographs alone limited surgeon understanding of fracture pattern. Because of difficulty understanding the posterior fracture fragment, we recommend preoperative CT on all trimalleolar fractures. LEVEL OF EVIDENCE: Diagnostic Level V. See Instructions for Authors for a complete description of levels of evidence.

Multiple Giant Cell Tumors of Tendon Sheath Found within a Single Digit of a 9-Year-Old.

Giant cell tumor of tendon sheath is one of the most common soft tissue tumors of the hand. These tumors typically occur in the third or fourth decade of life and present as solitary nodules on a single digit. Currently, the greatest reported number of lesions found within a single digit is five. Although uncommon, giant cell tumor of tendon sheath does occur in the pediatric population. Herein we present a report of a rare case of GCTTS in a child in which seven lesions were identified within a single digit-the greatest number of lesions within a single digit reported to date.

Importance of atrial surface area and refractory period in sustaining atrial fibrillation: testing the critical mass hypothesis.

OBJECTIVE: The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914; however, there have been few studies defining the relationship between atrial surface area and AF. This study evaluated the effect of tissue area and effective refractory period (ERP) on the probability of sustaining AF in an in vivo model. METHODS: Domestic pigs (n = 9) underwent median sternotomy. Epicardial activation maps were constructed from bipolar electrograms recorded from form-fitting electrode templates placed on the atria. Baseline ERPs were determined. ERP was lowered with a continuous infusion of acetylcholine (0.005-0.04 mg/Kg/min) until AF could be sustained after burst pacing. The atria were sequentially partitioned using bipolar radiofrequency ablation. ERPs were lowered using acetylcholine until AF could be sustained in each subdivision of atrial tissue. Each subdivision was further divided until AF was no longer inducible. At study completion, the heart was excised and the surface area of each section was measured. RESULTS: Over a range of ERPs from 75 to 250 ms, the probability of AF was correlated with increasing tissue area (range, 19.5-105 cm(2)) and decreasing ERP. Logistic regression analysis identified shorter ERP (P < .001) and larger area (P = .006) as factors predictive of an increased probability of sustained AF (area under the curve of the receiver-operator characteristic = 0.878). CONCLUSIONS: The probability of sustained AF was significantly associated with increasing tissue area and decreasing ERP. These data may lead to a greater understanding of the mechanism of AF and help to design better interventional procedures.