Abnormal Patterns of Biceps and Triceps Co-Contraction Following Elbow Surgery May Result in Elbow Stiffness.

Objectives: This study examines the pattern of muscular contraction and the intensity of this contraction of the biceps and triceps following elbow surgery. Methods: We performed a prospective electromyographic study of 16 patients undergoing 19 surgical procedures on the elbow joint. We measured the resting EMG signal intensity of the biceps and triceps of the operated and the normal sides at 90 degrees. We then calculated the peak EMG signal intensity during passive elbow flexion and extension of the operated side. Results: Seventeen of 19 elbows (89%) displayed a co-contraction pattern of the biceps and triceps near the end of flexion and extension during the passive range of motion. The co-contraction pattern was observed near the end of the range of motion in both flexion and extension. In addition to the observed co-contraction patterns, we detected higher contraction intensities for the biceps and triceps muscles in all patients in both flexion and extension for the elbows, which had been treated surgically. Further analysis suggests an inverse correlation between the biceps contraction intensity and the arc of motion measured at the latest follow-up. Conclusion: The co-contraction pattern and increased contraction intensity of periarticular muscle groups may result in internal splinting mechanisms, contributing to the development of elbow joint stiffness, which is frequently observed following elbow surgery.

Deep Learning Assistance Closes the Accuracy Gap in Fracture Detection Across Clinician Types.

BACKGROUND: Missed fractures are the most common diagnostic errors in musculoskeletal imaging and can result in treatment delays and preventable morbidity. Deep learning, a subfield of artificial intelligence, can be used to accurately detect fractures by training algorithms to emulate the judgments of expert clinicians. Deep learning systems that detect fractures are often limited to specific anatomic regions and require regulatory approval to be used in practice. Once these hurdles are overcome, deep learning systems have the potential to improve clinician diagnostic accuracy and patient care. QUESTIONS/PURPOSES: This study aimed to evaluate whether a Food and Drug Administration-cleared deep learning system that identifies fractures in adult musculoskeletal radiographs would improve diagnostic accuracy for fracture detection across different types of clinicians. Specifically, this study asked: (1) What are the trends in musculoskeletal radiograph interpretation by different clinician types in the publicly available Medicare claims data? (2) Does the deep learning system improve clinician accuracy in diagnosing fractures on radiographs and, if so, is there a greater benefit for clinicians with limited training in musculoskeletal imaging? METHODS: We used the publicly available Medicare Part B Physician/Supplier Procedure Summary data provided by the Centers for Medicare & Medicaid Services to determine the trends in musculoskeletal radiograph interpretation by clinician type. In addition, we conducted a multiple-reader, multiple-case study to assess whether clinician accuracy in diagnosing fractures on radiographs was superior when aided by the deep learning system compared with when unaided. Twenty-four clinicians (radiologists, orthopaedic surgeons, physician assistants, primary care physicians, and emergency medicine physicians) with a median (range) of 16 years (2 to 37) of experience postresidency each assessed 175 unique musculoskeletal radiographic cases under aided and unaided conditions (4200 total case-physician pairs per condition). These cases were comprised of radiographs from 12 different anatomic regions (ankle, clavicle, elbow, femur, forearm, hip, humerus, knee, pelvis, shoulder, tibia and fibula, and wrist) and were randomly selected from 12 hospitals and healthcare centers. The gold standard for fracture diagnosis was the majority opinion of three US board-certified orthopaedic surgeons or radiologists who independently interpreted the case. The clinicians' diagnostic accuracy was determined by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, sensitivity, and specificity. Secondary analyses evaluated the fracture miss rate (1-sensitivity) by clinicians with and without extensive training in musculoskeletal imaging. RESULTS: Medicare claims data revealed that physician assistants showed the greatest increase in interpretation of musculoskeletal radiographs within the analyzed time period (2012 to 2018), although clinicians with extensive training in imaging (radiologists and orthopaedic surgeons) still interpreted the majority of the musculoskeletal radiographs. Clinicians aided by the deep learning system had higher accuracy diagnosing fractures in radiographs compared with when unaided (unaided AUC: 0.90 [95% CI 0.89 to 0.92]; aided AUC: 0.94 [95% CI 0.93 to 0.95]; difference in least square mean per the Dorfman, Berbaum, Metz model AUC: 0.04 [95% CI 0.01 to 0.07]; p < 0.01). Clinician sensitivity increased when aided compared with when unaided (aided: 90% [95% CI 88% to 92%]; unaided: 82% [95% CI 79% to 84%]), and specificity increased when aided compared with when unaided (aided: 92% [95% CI 91% to 93%]; unaided: 89% [95% CI 88% to 90%]). Clinicians with limited training in musculoskeletal imaging missed a higher percentage of fractures when unaided compared with radiologists (miss rate for clinicians with limited imaging training: 20% [95% CI 17% to 24%]; miss rate for radiologists: 14% [95% CI 9% to 19%]). However, when assisted by the deep learning system, clinicians with limited training in musculoskeletal imaging reduced their fracture miss rate, resulting in a similar miss rate to radiologists (miss rate for clinicians with limited imaging training: 9% [95% CI 7% to 12%]; miss rate for radiologists: 10% [95% CI 6% to 15%]). CONCLUSION: Clinicians were more accurate at diagnosing fractures when aided by the deep learning system, particularly those clinicians with limited training in musculoskeletal image interpretation. Reducing the number of missed fractures may allow for improved patient care and increased patient mobility. LEVEL OF EVIDENCE: Level III, diagnostic study.

Assessment of a deep-learning system for fracture detection in musculoskeletal radiographs.

Missed fractures are the most common diagnostic error in emergency departments and can lead to treatment delays and long-term disability. Here we show through a multi-site study that a deep-learning system can accurately identify fractures throughout the adult musculoskeletal system. This approach may have the potential to reduce future diagnostic errors in radiograph interpretation.

Deep neural network improves fracture detection by clinicians.

Suspected fractures are among the most common reasons for patients to visit emergency departments (EDs), and X-ray imaging is the primary diagnostic tool used by clinicians to assess patients for fractures. Missing a fracture in a radiograph often has severe consequences for patients, resulting in delayed treatment and poor recovery of function. Nevertheless, radiographs in emergency settings are often read out of necessity by emergency medicine clinicians who lack subspecialized expertise in orthopedics, and misdiagnosed fractures account for upward of four of every five reported diagnostic errors in certain EDs. In this work, we developed a deep neural network to detect and localize fractures in radiographs. We trained it to accurately emulate the expertise of 18 senior subspecialized orthopedic surgeons by having them annotate 135,409 radiographs. We then ran a controlled experiment with emergency medicine clinicians to evaluate their ability to detect fractures in wrist radiographs with and without the assistance of the deep learning model. The average clinician's sensitivity was 80.8% (95% CI, 76.7-84.1%) unaided and 91.5% (95% CI, 89.3-92.9%) aided, and specificity was 87.5% (95 CI, 85.3-89.5%) unaided and 93.9% (95% CI, 92.9-94.9%) aided. The average clinician experienced a relative reduction in misinterpretation rate of 47.0% (95% CI, 37.4-53.9%). The significant improvements in diagnostic accuracy that we observed in this study show that deep learning methods are a mechanism by which senior medical specialists can deliver their expertise to generalists on the front lines of medicine, thereby providing substantial improvements to patient care.

A matched quantitative computed tomography analysis of 3 surgical approaches for osteochondral reconstruction of the capitellum.

BACKGROUND: The location of capitellar osteochondritis dissecans (OCD) lesions in the sagittal plane guides the surgical approach used for autologous osteochondral transplantation. We sought to compare the capitellar region accessible for orthogonal graft placement through 3 approaches: (1) posterior anconeus-split approach; (2) lateral approach with lateral collateral ligament (LCL) preservation (LCL-preserving lateral approach); and (3) lateral approach with LCL release (LCL-sacrificing lateral approach). METHODS: The 3 approaches were sequentially performed on 9 cadaveric elbows: posterior anconeus-split approach, LCL-preserving lateral approach, and LCL-releasing lateral approach. The extent of perpendicular access was delineated with Kirschner wires. Each specimen underwent computed tomography. The accessible region was quantified as degrees on the capitellum and converted into time on a clock, where 0° corresponds to the 12-o'clock position. Generalized estimating equation modeling was used to investigate for significant within-specimen, between-approach differences. RESULTS: The LCL-preserving and LCL-sacrificing lateral approaches provided more anterior perpendicular access than the posterior anconeus-split approach (mean, 0° vs 83°; P < .001). The posterior anconeus-split approach provided more posterior perpendicular access (mean, 215.0°; P < .001) than the LCL-preserving (mean, 117°; P < .001) and LCL-sacrificing (mean, 145°; P < .001) lateral approaches. The LCL-sacrificing lateral approach provided more posterior exposure than the LCL-preserving lateral approach (mean, 145° vs 117°; P < .001). The mean arc of visualization was greater for the LCL-sacrificing lateral approach than for the LCL-preserving lateral approach (145° vs 117°, P < .001). CONCLUSIONS: A capitellar OCD lesion can be perpendicularly accessed from a posterior anconeus-split approach if it is posterior to 83° (2:46 clock-face position). A laterally based approach may be required for lesions anterior to this threshold. These data inform clinical decisions regarding the appropriate surgical approach for any OCD lesion.

Location of Osteochondritis Dissecans Lesions of the Capitellum.

PURPOSE: The location of capitellar osteochondritis dissecans (OCD) lesions in the sagittal plane guides the surgical approach, and lesion location in the coronal plane influences surgical management. Although most lesions have been reported to occur between 4 o'clock and 4:30 (120° to 135° anterior to the humerus), some lesions are located elsewhere in the capitellum. The primary aim was to define the region of the capitellum affected by OCD lesions using a novel clock-face localization system. METHODS: We reviewed 104 magnetic resonance imaging examinations diagnosing a nontraumatic capitellar OCD lesion. In the sagittal plane, lesion margins were recorded as degrees on the capitellum and converted into a clock-face format in which 0° corresponds to 12:00 with the forearm facing to the right. The 0° axis (12-o'clock axis) was defined as a line parallel to the anterior humeral line that intersects the capitellum center. The following coronal measurements were recorded: lesion width, capitellar width, and distance between the lateral capitellum and lateral lesion. Two independent observers took measurements. RESULTS: In the sagittal plane, average lesion location was 92° to 150° (3:04-5:00, clock face) and ranged from 52.1° to 249.5° (1:44-8:19, clock face). Average lesion dimensions were 10.7 mm (mediolateral width) and 5.2 mm (anteroposterior depth). Interrater reliability was high (intraclass correlation coefficient = 0.98). CONCLUSIONS: Using a magnetic resonance imaging-based clock-face localization system, we found that capitellar OCD lesions affect a broad region of the capitellum in the sagittal plane. CLINICAL RELEVANCE: The clock-face localization system allows for precise description of capitellar OCD lesion location, which may facilitate intraoperative decision and longitudinal monitoring.

Nonspanning Total Wrist Arthrodesis with a Low-Profile Locking Plate.

Purpose This study aims to compare the outcomes and complications of our technique for nonspanning total wrist arthrodesis using a locking plate with the standard carpometacarpal spanning technique. Methods A retrospective review of charts was performed to identify patients who underwent total wrist arthrodesis by the senior author (S.W.W.). We compared the outcomes of 15 cases of nonspanning wrist fusion with a 2.4/2.7 mm locking T plate to 11 cases of spanning wrist fusion with a 2.7/3.5 mm locking compression plate. Minimum follow-up was 3 months. Indications for fusion included rheumatoid arthritis, posttraumatic arthritis, Kienböck's disease, primary osteoarthritis, juvenile inflammatory arthropathy, psoriasis, brachial plexopathy, failed hemi or total wrist arthroplasty, failed four-corner fusion, and failed proximal row carpectomy. The primary outcome was fusion. Secondary outcomes included time to union, patient-rated wrist evaluation score, numerical rating scale pain score, grip strength, and complications. Results All the wrists got fused. There were no significant differences in objective and subjective outcomes between cohorts. There were three complications (27%) in the spanning group, including tendon rupture and peri-implant fracture at the third metacarpal. This was compared with three complications (20%) in the nonspanning group, consisting of hardware removal. Discussion We achieved similar fusion rates employing both spanning and nonspanning total wrist arthrodesis techniques, without necessitating carpometacarpal arthrodesis in the latter. Complications associated with our method were comparably less severe than those reported in the literature. We advocate nonspanning arthrodesis as an alternative method for total wrist fusion with a high union rate and minimal risk of complications at the carpometacarpal joint. Level of Evidence Therapeutic level IV.

Prevalence of Os Styloideum in National Hockey League Players.

BACKGROUND: Os styloideum describes an accessory carpal ossicle between the trapezoid, the capitate, and the second and third metacarpals. Injuries to this tissue have been described as part of the carpal boss syndrome. While the etiology of os styloideum remains uncertain, it may represent a physiologic response to altered loading forces in the wrist, similar to the development of cam-type deformity in the hips of ice hockey players or the Bennett lesion in the shoulders of baseball pitchers. HYPOTHESIS: Professional hockey players will have a higher prevalence of os styloideum compared with the general population. STUDY DESIGN: Case series. LEVEL OF EVIDENCE: Level 4. METHODS: A retrospective review of 16 professional hockey players from 4 different National Hockey League (NHL) teams who underwent unilateral imaging of the wrist was performed. Seventeen wrists were reviewed for the presence of os styloideum. RESULTS: Thirteen of 16 players (81%) had an os styloideum, representing an increased prevalence compared with the general population. Previous clinical and cadaveric studies estimated a general prevalence of up to 19% ( P < 0.001). For the 10 players who had their leading wrist scanned, 9 had an os styloideum (90%). Ten of 11 (91%) players demonstrated a bone marrow edema pattern within the metacarpal and the os styloideum on magnetic resonance imaging. There was no significant association between the presence of an os styloideum and the player's position, leading wrist, or years in the league. CONCLUSION: There appears to be an increased prevalence of os styloideum among NHL players, and team physicians should consider this finding while formulating a differential diagnosis for dorsal wrist pain. CLINICAL RELEVANCE: This study identified NHL players as having an increased prevalence of os styloideum compared with the general population. By doing so, these findings represent an opportunity to enhance our understanding of the etiology, clinical significance, and treatment of os styloideum.

Injuries to the Collateral Ligaments of the Metacarpophalangeal Joint of the Thumb, Including Simultaneous Combined Thumb Ulnar and Radial Collateral Ligament Injuries, in National Football League Athletes.

BACKGROUND: Thumb collateral ligament injuries occur frequently in the National Football League (NFL). In the general population or in recreational athletes, pure metacarpophalangeal (MCP) abduction or adduction mechanisms yield isolated ulnar collateral ligament (UCL) and radial collateral ligament (RCL) tears, respectively, while NFL athletes may sustain combined mechanism injury patterns. PURPOSE: To evaluate the incidence of simultaneous combined thumb UCL and RCL tears among all thumb MCP collateral ligament injuries in NFL athletes on a single team. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A retrospective review of all thumb injuries on a single NFL team from 1991 to 2014 was performed. All players with a thumb MCP collateral ligament injury were included. Collateral ligament injuries were confirmed by review of both physical examination findings and magnetic resonance imaging. Player demographics, surgical details, and return-to-play data were obtained from the team electronic medical record and surgeons' records. RESULTS: A total of 36 thumbs in 32 NFL players were included in the study, yielding an incidence of 1.6 thumb MCP collateral ligament injuries per year on a single NFL team. Of these, 9 thumbs (25%) had a simultaneous combined UCL and RCL tear injury pattern confirmed on both physical examination and MRI. The remaining 27 thumbs (75%) were isolated UCL injuries. All combined UCL/RCL injuries required surgery due to dysfunction from instability; 63.0% of isolated UCL injuries required surgical repair ( P = .032) due to continued pain and dysfunction from instability. Repair, when required, was delayed until the end of the season. All players with combined UCL/RCL injuries and isolated UCL injuries returned to play professional football the following season. CONCLUSION: Simultaneous combined thumb UCL and RCL tear is a previously undescribed injury pattern that occurred in 25% of thumb MCP collateral ligament injuries on a single NFL team over a 23-year period. All players with combined thumb UCL/RCL injuries required surgical repair, which was significantly higher compared with players with isolated UCL injuries. Team physicians and hand surgeons treating elite football players with suspected thumb collateral ligament injuries should examine for RCL and UCL instability and consider MRI if any concern exists for a combined ligament injury pattern, as this injury is likely frequently missed.

Outcomes after operative treatment of elbow contractures in the pediatric and adolescent population.

BACKGROUND: The role of elbow contracture release in the very young is unclear, with existing studies reporting conflicting results. This study evaluated the long-term results after open elbow contracture release in patients aged younger than 18 years. METHODS: Between 1994 and 2012, 32 patients underwent open elbow contracture release at a mean age of 13.8 years (range, 5-18 years), and their outcomes were reviewed. The primary cause was traumatic in 30 patients (4 radial head/neck fractures, 5 intra-articular distal humeral fractures, 11 extra-articular distal humeral fractures, 10 complex fracture-dislocations), and the mean time from the index injury to contracture release was 16.3 months (range, 3-82 months). The cause in 2 patients was nontraumatic (1 osteochondritis dessicans, 1 congenital). The mean follow-up period was 66 months (range, 7-202 months). RESULTS: At the latest follow-up, total arc of motion improved from 69° to 123° (P <.0001), with a mean increase of 54° (P <.0001). The function arc was >100° in 28 patients (88%), and 29 patients (91%) achieved >20° of improvement in their arc. Twelve patients (38%) underwent a gentle manipulation under anesthesia at a mean of 2.7 weeks (range, 1-5 weeks) for early recurrence of stiffness. There were 3 complications (1 deep infection, 1 hematoma, 1 humeral fracture through the external fixator pin site). No patients lost motion after surgery. CONCLUSION: Elbow contracture release in the pediatric and adolescent population can provide significant improvements in range of motion similar to that achieved in adults. The improvements in motion are durable.

Conservative management of elbow dislocations with an overhead motion protocol.

PURPOSE: To report the results of using an overhead motion protocol in 27 patients and to assess final range of motion and incidence of persistent instability in this cohort. METHODS: A total of 27 patients were included who sustained a simple elbow dislocation and were treated nonsurgically with an overhead motion protocol designed to convert gravity from a distracting to a stabilizing force. Motion was initiated within 1 week of injury and average follow-up was 29 months. Final arc of motion and prevalence of instability were the primary outcomes measures. RESULTS: Final mean arc of extension to flexion was from 6° to 137°, and of pronation to supination was from 87° to 86°. No recurrent instability was observed in this cohort and all patients were fully functional and without limitations at latest follow-up. CONCLUSIONS: The overhead motion protocol was a reliable rehabilitation program after elbow dislocation that allowed for controlled early motion by placing the elbow in an inherently stable position. Prompt initiation of motion in a protected position can optimize final motion and satisfaction outcomes, and when done in a mechanically advantageous position it can potentially limit the risk of recurrent instability. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Capitellum Fracture Fragment Excision: a Case Series.

BACKGROUND: Fractures of the capitellum are rare injuries, and few studies have reported the results of fragment excision. QUESTIONS/PURPOSES: The purpose of this study was to determine range of motion and short-term clinical outcomes for patients treated with capitellum excision. METHODS: A retrospective review was performed to identify all patients with an isolated capitellum fracture who underwent excision as definitive treatment at our institutions. Mechanism of injury, associated elbow injuries, type of capitellum fracture, complications, and postoperative outcomes including final elbow range of motion (ROM), elbow instability, and Disabilities of the Arm, Shoulder and Hand (DASH) score were recorded. RESULTS: Four patients met the inclusion and exclusion criteria of this study. All patients were female with an average age of 69 years (range 42-85). Based on the Bryan and Morrey classification system, three (75%) fractures were classified as type I and one (25%) fracture as type III. The average clinical follow-up was 11 months. Final examination demonstrated a mean elbow range of motion from 14° (range 0-30) of extension to 143° (range 130-160) of flexion. All patients had full forearm rotation, and there was no clinical evidence of elbow instability. The average DASH score was 18.3 (12.5-24.2) at final follow-up. CONCLUSION: Excision of the capitellum, much like excision of the radial head, results in acceptable short-term outcome scores and elbow range of motion in patients with fractures that are not amenable to open reduction and internal fixation.

Outcomes of anconeus interposition for proximal radioulnar synostosis.

BACKGROUND/HYPOTHESIS: Proximal radioulnar synostosis after elbow injuries can produce debilitating contractures. The estimated range of motion required to perform many activities of daily living is a 100° arc of forearm rotation. We hypothesized that excision of heterotopic bone and anconeus flap interposition could restore functional prono-supination in patients with proximal radioulnar synostosis. METHODS: Patients with proximal radioulnar synostosis were subdivided into 2 groups on the basis of etiology: (1) as a complication after distal biceps tendon repair or (2) as a result of direct trauma to the proximal forearm/elbow. All patients underwent an excision of the synostosis with interposition of an anconeus flap and were observed clinically for a minimum of 6 months. RESULTS: Twenty-three patients (16 men, 7 women) were included, with a mean age of 47 years and mean clinical follow-up of 4.8 years. Mean arc of forearm rotation improved from 21° to 132°, pronation increased from 12° to 70°, and supination increased from 9° to 62° (P < .0001). Patients with biceps tendon repair etiology (n = 7) displayed greater gains in pronation and a trend toward greater total forearm rotation than did those with a traumatic etiology (n = 16). CONCLUSION: Anconeus interposition flap for management of proximal radioulnar synostosis produces significant and reliable clinical improvement in elbow prono-supination. Patients with biceps tendon repair etiology had a trend toward greater motion improvement than that of patients with a traumatic etiology. The degree of improvement seen would provide nearly full restoration of functional motion, resulting in minimal limitations in activities of daily living.

Management of acute and chronic vascular conditions of the hand.

Management of acute and chronic vascular disorders of the hand in patients with vasospastic and vaso-occlusive disorders is a complex problem and requires a multidisciplinary approach. The ischemia-related pain, skin ulcerations, and ultimately the threat of digital gangrene require a concerted effort to improve perfusion using a combination of medications and surgery. The purpose of this work is to review our experience over the past 2 decades with this cohort of patients including the variability of the clinical presentation, a method of classification, and a practical treatment philosophy.

Direct repair for managing acute and chronic lateral ulnar collateral ligament disruptions.

PURPOSE: Acute elbow injuries that disrupt the lateral ulnar collateral ligament and result in posterolateral rotatory instability usually require surgical treatment. The 2 technical options reported, direct repair and use of a palmaris longus tendon graft, have usually favored the use of the graft. To balance this emphasis, we report our experience with direct repair of the humeral origin in cases of trauma, whether acute, delayed, or recurrent. It was our hypothesis that because the humeral origin is the point of failure and separation, restoration of this attachment is sufficient to restore stability and durable function without the need for a graft. METHODS: Patients with complete disruption of the posterolateral ligaments of the elbow, who were managed with direct repair to the humeral origin, were included. Patients were separated into an acute treatment group (< 30 d from injury to treatment) and a delayed treatment group (> 30 d). Mayo Elbow Performance Scores and postoperative range of motion were collected from patient records. RESULTS: A total of 34 patients were included with a mean follow-up of 42 months. No difference was seen in Mayo Elbow Performance Scores between acute (mean, 90) or delayed treatment (mean, 89) of the lateral ulnar collateral ligament tear. No difference was seen in final elbow flexion or extension. Two patients in the acute group had failure of the direct repair requiring intervention. In the delayed group, no patients had recurrent instability. CONCLUSIONS: No significant difference in clinical outcome or range of motion was observed after direct repair of traumatic tears of the lateral ulnar collateral ligament tear between acute and delayed treatment cohorts. Despite complete disruption of the posterolateral ligaments, direct repair of the torn ligament to its humeral origin was effective without supplemental tendon graft reconstruction irrespective of interval from injury to repair, mechanism of injury, or associated fractures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Magnetic resonance imaging findings in acute elbow dislocation: insight into mechanism.

PURPOSE: To identify with magnetic resonance imaging the location and severity of ligamentous injury after acute elbow dislocations. Based on observations that many elbow dislocations arise from an initial acute valgus load, we hypothesized that all patients would have a high-grade medial injury but not all would demonstrate injury of the lateral ligaments. METHODS: The medial collateral ligament was subdivided into anterior bands of the anterior bundle of the medial collateral ligament (MCL) and posterior bands of the anterior bundle of the MCL, whereas the lateral collateral ligament was divided into the lateral ulnar collateral ligament and the radial collateral ligament. Distinction on magnetic resonance imaging was made between normal morphology and low-grade partial tear (< 50% of the ligament fibers), high-grade partial tear (≥ 50%), and full-thickness disruption. The site of disruption was also characterized. RESULTS: Acute magnetic resonance imaging studies for 16 patients were included. No low-grade tears or intact evaluations of either the anterior or posterior bands of the anterior bundle of the MCL were observed; most demonstrated complete tears. The lateral ulnar collateral ligament most frequently showed complete disruption but was occasionally intact. The radial collateral ligament infrequently showed full disruption. Complete tears involving either the anterior or posterior portions of the anterior band of the MCL were significantly more common than complete tears involving the ligaments on the lateral side. CONCLUSIONS: After elbow dislocation, complete ligamentous tears were more common on the medial versus the lateral side. Whereas the lateral ligaments were occasionally preserved, this was never observed on the medial side. These data suggest a sequence of failure starting on the medial side with subsequent variable energy dissipation laterally. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IV.

Capitellum excision: Mechanical implications and clinical consequences.

Controversy exists regarding the optimal treatment of isolated fractures of the capitellum that are not amenable to open reduction and internal fixation. Excision of the capitellum could result in instability of the elbow, though only limited the clinical or laboratory evidence exists to support this outcome. The aim of our study was to determine if capitellum excision leads to significant instability by measuring the relative change in varus-valgus displacement of the elbow. The varus-valgus displacement was recorded in 11 cadaveric elbows before and after isolated excision of the capitellum. Specimens were testing in varus-loaded and valgus-loaded positions with and without a 1 kg weight on the forearm. The varus-valgus displacement at the elbow was measured using a 3D motion capture system. Capitellum excision did not significantly change varus-valgus displacements in either the adducted, varus, or valgus position of the elbow (p = 0.80, p = 0.28, p = 0.51). Furthermore, the addition of the 1 kg external functional load to the forearm did not produce a significant change in the varus and valgus loaded positions (p = 0.16, p = 0.36). Our results demonstrate that excision of the capitellum in the setting of intact ligamentous structures does not result in significant instability in either the adducted varus loaded or valgus loaded positions of the elbow.

An online video investigation into the mechanism of elbow dislocation.

PURPOSE: Acute elbow instability leading to dislocation is thought to be a spectrum initiated by an injury to the lateral stabilizing structures of the elbow. Previous cadaveric studies have shown elbow dislocations to occur in flexion. The purpose of this study was to analyze videographic evidence of the deforming forces and upper extremity position during elbow dislocations. We sought to corroborate previous biomechanics studies with in vivo observations. METHODS: We included 62 YouTube.com videos with a clear videographic view of an elbow dislocation. Three senior elbow surgeons independently evaluated arm position at the time of dislocation, along with the suspected deforming forces at the elbow based on these positions. RESULTS: Of the 62 visualized elbow dislocation events, the vast majority (92%) dislocated at or near full extension. The most common arm positions were forearm pronation (68%) with shoulder abduction (97%) and forward flexion (63%). The typical elbow deforming forces were a valgus moment (89%), an axial load (90%), and progressive supination (94%). We identified 4 discrete patterns of arm position and deforming forces. CONCLUSIONS: Acute elbow dislocations in vivo occur in relative extension irrespective of forearm position, a finding distinct from previous cadaveric studies. The most common mechanism appears to involve a valgus moment to an extended elbow, which suggests a requisite disruption of the medial collateral ligament, the known primary constraint to valgus force. These videographic findings suggest that some acute elbow dislocations may result from acute valgus instability and therefore are distinct in nature and mechanism from posterolateral rotatory instability. This information could lead to improved understanding of the sequence of structural failure, modification of rehabilitation protocols, and overall treatment.

The influence of gravity on the unstable elbow.

BACKGROUND: Safely permitting early range of motion after a destabilizing injury to the elbow is believed to optimize return of function. However, the range-of-motion exercises must be balanced against the risk of re-dislocation or subluxation. The goal of this study was to describe the position of the upper limb that permitted the greatest motion while minimizing the risk of re-dislocation or subluxation. METHODS: Seven cadaveric elbows were affixed with a 3-dimensional motion capture system. Ulnohumeral distraction was recorded at flexion angles from 10° to 90° for intact, approach only (sham procedure), and LCL-sectioned. Ulnohumeral separation was recorded in 3 distinct positions of the upper limb that are frequently used in a clinical setting: 1) trunk seated upright with arm at the side; 2) trunk seated upright with elbow in hinged-brace; and 3) trunk supine with shoulder flexed and internally rotated - "gravity-assisted overhead motion" protocol. RESULTS: A significant ulnohumeral distraction difference was found between the supine and the upright protocols. Upon direct comparison, 104% more displacement occurred across the ulnohumeral joint in the upright LCL-sectioned condition compared to the supine LCL-sectioned condition (P = .001). The greatest ulnohumeral distraction occurred in the seated upright range of motion with a hinged elbow brace (range, 2.5-5.6 mm). CONCLUSION: The overhead motion protocol is a safe protocol for unstable elbows. The supine position results in the least amount of ulnohumeral distraction across flexion angles from 10° to 90°. The upright protocols, especially with the hinged elbow brace, exhibited ulnohumeral distraction that may result in dislocation.