A narrative review of little league shoulder: proximal humeral physis widening is only one piece of the puzzle, it is time to consider posterior glenoid dysplasia.

Baseball athletes across all levels of play are at an increased risk for upper extremity injury due to the supraphysiologic demands on the shoulder and elbow during overhead throwing. Little league baseball players present with a unique subset of injuries that can affect the growth plate, commonly at the shoulder or the elbow. Ascertaining a diagnosis and plan of care for little league shoulder (LLS) historically focuses on the proximal humeral physis in skeletally immature throwing athletes presenting with shoulder pain. However, while not a current standard of care, posterior glenoid dysplasia is often present in youth baseball athletes presenting with LLS, warranting a shift in the way clinicians evaluate for and treat the youth baseball athlete's pathologic shoulder. Therefore, purpose of this narrative review is 2-fold: first, to describe the current standard of care as it relates to a diagnosis of LLS, and second, to critically describe a comprehensive evaluation process for youth throwing athletes with shoulder pain that includes screening for evidence of posterior glenoid dysplasia. This paper summarizes the current state of the available evidence for anatomic considerations of LLS in the baseball athletes throwing shoulder. Additionally, we provide a framework for clinical evaluation using a multidisciplinary approach to evaluate the entire kinetic chain of the youth baseball athlete presenting with LLS and posterior glenoid dysplasia. A case study is presented to describe common presentations, clinical and objective examinations, and a plan of care from time of evaluation to return to throwing.

Supporting self-management for patients with Interstitial Lung Diseases: Utility and acceptability of digital devices.

INTRODUCTION: Patients diagnosed with Interstitial Lung Diseases (ILD) use devices to self-monitor their health and well-being. Little is known about the range of devices, selection, frequency and terms of use and overall utility. We sought to quantify patients' usage and experiences with home digital devices, and further evaluate their perceived utility and barriers to adaptation. METHODS: A team of expert clinicians and patient partners interested in self-management approaches designed a 48-question cross-sectional electronic survey; specifically targeted at individuals diagnosed with ILD. The survey was critically appraised by the interdisciplinary self-management group at Royal Devon University Hospitals NHS Foundation Trust during a 6-month validation process. The survey was open for participation between September 2021 and December 2022, and responses were collected anonymously. Data were analysed descriptively for quantitative aspects and through thematic analysis for qualitative input. RESULTS: 104 patients accessed the survey and 89/104 (86%) reported a diagnosis of lung fibrosis, including 46/89 (52%) idiopathic pulmonary fibrosis (IPF) with 57/89 (64%) of participants diagnosed >3 years and 59/89 (66%) female. 52/65(80%) were in the UK; 33/65 (51%) reported severe breathlessness medical research council MRC grade 3-4 and 32/65 (49%) disclosed co-morbid arthritis or joint problems. Of these, 18/83 (22%) used a hand- held spirometer, with only 6/17 (35%) advised on how to interpret the readings. Pulse oximetry devices were the most frequently used device by 35/71 (49%) and 20/64 (31%) measured their saturations more than once daily. 29/63 (46%) of respondents reported home-monitoring brought reassurance; of these, for 25/63 (40%) a feeling of control. 10/57 (18%) felt it had a negative effect, citing fluctuating readings as causing stress and 'paranoia'. The most likely help-seeking triggers were worsening breathlessness 53/65 (82%) and low oxygen saturation 43/65 (66%). Nurse specialists were the most frequent source of help 24/63 (38%). Conclusion: Patients can learn appropriate technical skills, yet perceptions of home-monitoring are variable; targeted assessment and tailored support is likely to be beneficial.

Return to Sport and Clinical Outcomes Following Osteochondral Autograft Transplantation in Baseball Players and Gymnasts With Unstable Osteochondritis Dissecans: A Critically Appraised Topic.

CLINICAL SCENARIO: Osteochondritis dissecans (OCD) of the capitellum is a condition occurring at the elbow and often seen in both baseball players and gymnasts due to the repetitive loading of the radiocapitellar joint. Treatment options for OCD vary and are dependent on lesion presentation, elbow motion, and growth plate maturity. OCD lesions categorized as unstable can be treated with an osteochondral autograft transplantation surgery (OATS). FOCUSED CLINICAL QUESTION: In an adolescent population, what are the return to sport rates and clinical outcomes following OATS in baseball players and gymnasts with unstable OCD lesions? SUMMARY OF KEY FINDINGS: Three articles met the inclusion criteria for this appraisal, and all indicate an OATS procedure should be considered in the management of unstable OCD lesions. Return to play outcomes were favorable for both baseball players and gymnasts. Self-reported patient function and elbow extension all improved following an OATS. CLINICAL BOTTOM LINE: An OATS procedure is a favorable option for the management of OCD lesions of the elbow in baseball players and gymnasts. STRENGTH OF RECOMMENDATION: There is level B evidence to support return to sport and clinical outcomes in baseball players and gymnasts following an OATS procedure. This score is directly related to the quality of evidence that currently exists on the topic.

Dynamic Posterior Instability Test: A New Test for Posterior Glenohumeral Instability.

Background: Recurrent posterior shoulder instability has become an increasingly recognized cause of shoulder disability, especially among athletes. The presentation can be vague and therefore its clinical diagnosis is often overlooked. Few diagnostic tests exist and these tests are difficult to perform in an anxious and apprehensive patient. Many also lack high specificity and do not effectively distinguish posterior labral tears from other shoulder pathologies. As a result, the authors worked to develop a new test, the dynamic posterior instability test (DPIT). The purpose of this study was to describe the DPIT as well as a modified DPIT test and to evaluate the accuracy of these tests in detecting posterior labral pathology. It was hypothesized that the dynamic posterior instability test (DPIT) would improve accuracy in the evaluation of posterior labral tears. Methods: For a 9-month period, the DPIT and modified DPIT tests were performed on all patients evaluated for posterior instability of the shoulder. The records of all patients who had undergone a posterior labral repair (type VIII SLAP and posterior labral tears) were reviewed. The results of the DPIT and modified DPIT tests were compared to intra-operative findings. Anterior glenohumeral instability patients were also evaluated with these tests to serve as a control. Results: Fifty-one patients had a positive and 3 patients had a negative DPIT test. Of the anterior instability patients, there was 1 positive and 19 negative test results. The sensitivity of the DPIT test was 94.4%, specificity 95%, the positive predictive value 0.98, and the negative predictive value 0.86. The results of the modified DPIT were the same as the DPIT test. Conclusions: The DPIT and modified DPIT tests provide a valuable new tool when combined with history and other physical examination findings improve the accuracy of diagnosis of posterior shoulder instability.

Differences in Shoulder Internal Rotation Strength Between Baseball Players With Ulnar Collateral Ligament Reconstruction and Healthy Controls.

BACKGROUND: Studies have indicated decreased shoulder internal rotation (IR) and external rotation (ER) strength in the throwing limb of baseball players after ulnar collateral ligament injury. There is limited evidence on the recovery of shoulder rotation strength after primary ulnar collateral ligament reconstruction (UCLR). HYPOTHESIS: At the time of return to throwing, baseball players who underwent UCLR would demonstrate decreased IR and ER shoulder strength in the throwing arm as compared with healthy baseball players. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Male competitive high school and collegiate baseball athletes participated in this study. Athletes who underwent UCLR were compared with healthy controls who were matched by age, height, weight, and position. Bilateral isometric shoulder ER and IR strength was measured using a handheld dynamometer for all participants at the time of initial evaluation (UCLR group) and throughout the course of a season (healthy group). Independent t tests were run to calculate mean differences in ER and IR shoulder strength between the groups, with significance set at P < .05. RESULTS: A total of 86 baseball athletes participated in this study (43 UCLR group, 43 healthy group). At the time of return to throwing (mean ± SD, 194 ± 30 days postoperatively), the 2 groups demonstrated no significant differences in nonthrowing arm ER or IR strength (P = .143 and .994, respectively). No significant difference was found between groups for throwing arm ER strength (P = .921); however, the UCLR group demonstrated significantly less throwing arm IR strength than the healthy group (144.2 ± 27.8 vs 157.6 ± 27.1 N; P = .023). CONCLUSION: The results of this study demonstrate that throwing arm rotator cuff strength may not fully recover before the initiation of a return-to-throwing program after UCLR. These data provide a potential framework for clinicians to assist in the management and exercise prescription of the baseball athlete after UCLR and before medical release and the initiation of a return-to-throwing program.

Hypertrophy of the sublime tubercle in elbow ulnar collateral ligament injuries: a case series of baseball pitchers undergoing ulnar collateral ligament reconstruction with short-term follow-up.

Background: The ulnar collateral ligament (UCL) of the elbow is subject to repetitive stress in overhead throwing athletes. This can lead to morphologic changes at the bony attachments of the UCL and hypertrophy of the sublime tubercle. The purpose of this case series is to describe the surgical details and clinical outcomes of a series of competitive baseball pitchers with hypertrophic sublime tubercles who underwent UCL reconstruction (UCLR). Methods: All baseball pitchers who were treated for UCL injuries with significant hypertrophy of the sublime tubercle on preoperative imaging were included in the series. Clinical history, preoperative imaging, intraoperative findings during UCLR, and postoperative outcomes measured with the Conway scale were described. Results: Ten players (average age of 22.9 years [range 13-39]) were included (average follow-up 20.4 months [range 3-38 months]). Five patients also had symptoms of ulnar nerve compression, with 4 requiring transposition at the time of ULCR and 1 at 3 months postoperatively. Bony hypertrophy of the sublime tubercle was confirmed intraoperatively in all cases and excised before UCLR with the docking technique. Of the 7 patients with at least 12-month follow-up postoperatively, 6 had excellent outcomes, and 1 had a fair outcome. Conclusion: Although UCLR in the setting of hypertrophic sublime tubercle can be more complex than typical UCLR, excellent outcomes are achievable with preoperative recognition and surgical planning.

Differences in Passive Shoulder Range of Motion Between Baseball Players With Neurogenic Thoracic Outlet Syndrome and Matched Healthy Controls.

BACKGROUND: Neurogenic thoracic outlet syndrome (nTOS) is becoming more recognized as a diagnosis in the throwing athlete. Currently, there is limited information on the clinical presentation and development of nTOS in baseball players. PURPOSE: To compare passive shoulder range of motion (ROM) and anatomic humeral retrotorsion (HRT) of baseball players diagnosed with nTOS with a group of healthy, matched controls. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 53 adolescent baseball players diagnosed with nTOS (age, 17.2 ± 2.3 years; height, 180.9 ± 10.1 cm; weight, 80.0 ± 13.3 kg) were compared with 53 healthy baseball players (age, 17.2 ± 2.4 years; height, 183.9 ± 9.0 cm; weight, 83.8 ± 11.5 kg). Participants were measured for shoulder internal rotation (IR) and external rotation (ER) ROM and HRT. All measurements were taken bilaterally, and the differences (throwing to nonthrowing arm) were used to calculate mean values for glenohumeral internal rotation difference, glenohumeral external rotation difference (GERD), total rotational motion difference (TRMdiff), and anatomic humeral retrotorsion difference. Group comparisons were made between the nTOS and control players using multivariate analysis of variance, and descriptive comparisons were made with independent t tests. RESULTS: There were no significant differences between groups in age, height, weight, or years of experience. Players in the nTOS group had significantly less throwing arm ER compared with controls (103.4° ± 10.4° vs 109.6° ± 7.5°, respectively; P = .001) and GERD (3.0° ± 9.2° vs 8.8° ± 9.2°, respectively; P = .002). TRMdiff was significantly greater in nTOS (-11.1° ± 11.1°) than in controls (-3.7° ± 9.4°) (P < .001). CONCLUSION: In the current study, adolescent baseball players diagnosed with nTOS were evaluated with shoulder ROM differences when compared with a matched healthy cohort. A loss of throwing arm ER appeared to be the main factor behind shoulder ROM changes in the nTOS group.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury.

BACKGROUND: Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development. HYPOTHESIS: In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff). RESULTS: There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940). CONCLUSION: Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.

Traumatic Elbow Instability: How to Fix It and When to Phone a Friend.

Traumatic elbow instability is a difficult condition to manage. Many surgeons consider the elbow a perplexing black box and evaluating damaged structures in the setting of pain and swelling a diagnostic challenge. Injury most commonly occurs from a fall onto an outstretched hand but also results from elbow dislocation, direct trauma, and sporting activities. The injury can initiate on the medial or lateral side, depending on forearm position at the time of injury, and usually follows a predictable pattern, with progressive instability caused by soft-tissue disruption and fractures of the medial or lateral column. Primary medial instability, lateral instability, and combined injury patterns have been described and discussed. Simple elbow dislocations and certain fractures can be managed nonsurgically, whereas complex patterns of instability and fracture-dislocations routinely require surgery. Stiffness and nerve injury are the most common complications and occur from both surgical and nonsurgical management. This chapter describes the diagnosis and management of traumatic elbow instability and the management of its sequela.

The Effect of Direct Oral Anti-Coagulants on Delayed Traumatic Intracranial Hemorrhage After Mild Traumatic Brain Injury: A Systematic Review.

BACKGROUND: The use of anticoagulant medications leads to a higher risk of developing traumatic intracranial hemorrhage (tICH) after a mild traumatic brain injury (mTBI). The management of anticoagulated patients can be difficult to determine when the initial head computed tomography is negative for tICH. There has been limited research on the risk of delayed tICH in patients taking direct oral anticoagulant (DOAC) medications. OBJECTIVE: Our aim was to determine the risk of delayed tICH for patients anticoagulated with DOACs after mTBI. METHODS: We conducted a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched several medical databases to examine the risk of delayed tICH in patients on DOACs. RESULTS: There were 1252 nonduplicate studies that were identified through an initial database search, 15 of which met our inclusion and exclusion criteria and were included in our analysis after full-text review. A total of 1375 subjects were combined among the 15 studies, with 20 instances of delayed tICH after mTBI. Nineteen of the 20 patients with a delayed tICH were discharged without any neurosurgical intervention, and 1 patient on apixaban died due to a delayed tICH. CONCLUSIONS: This systematic review confirms that delayed tICH after mTBI in patients on DOACs is uncommon. However, large, multicenter, prospective studies are needed to confirm the true incidence of clinically significant delayed tICH after DOAC use. Due to the limited data, we recommend using shared decision-making for patients who are candidates for discharge.

Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole.

The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.

RESIDENTS CASE REPORT: MUSCULOCUTANEOUS NERVE INJURY IN A COLLEGIATE BASEBALL PITCHER.

BACKGROUND: Literature regarding musculocutaneous nerve injuries among the athletic population is scarce, with only several reported clinical cases among baseball and softball pitchers. PURPOSE: To present a unique case of a musculocutaneous nerve injury to aid in clinician awareness and propose innovative rehabilitation practices that may facilitate improved patient outcomes during recovery. CASE DESCRIPTION: A 23-year-old Division 1 NCAA collegiate baseball pitcher presented with vague anterior arm pain following a pre-season game. The athlete described the pain as an "intense stretch" of his right arm that occurred during his last pitch. The initial evaluation identified tenderness over the right distal bicep. All shoulder and elbow orthopedic tests to assess shoulder impingement, labral pathologies, and glenohumeral instability were unremarkable. Increased neural tension was also noted with upper limb neurodynamic testing of the median and ulnar nerves on the right arm compared bilaterally. Electromyography (EMG) testing confirmed a right upper and mid-brachial plexus stretch injury with the primary involvement of the musculocutaneous nerve. Rehabilitation focused on restoring strength deficits and diminishing neural tension. Blood flow restriction (BFR) was introduced on the uninvolved limb to reduce deficits in bicep musculature strength. Once the athlete regained bicep strength and forearm sensation, he was progressed from flat-ground throwing activities to throwing off the mound. OUTCOMES: A reduction in neural tension during neurodynamic testing of the right arm, improvement of bicep brachii deficits seen between the right and left limbs, and restoration of sensation in the right lateral forearm enabled a progressive return to sport. DISCUSSION: Due to vague reports and inconclusive findings, the initial presentation of musculocutaneous nerve injuries may be mistaken for other conditions such as a biceps brachii strain. Further -documentation of this injury and rehabilitation procedures are needed to enhance patient outcomes.

Posterior Labral Injury and Glenohumeral Instability in Overhead Athletes: Current Concepts for Diagnosis and Management.

Posterior glenohumeral instability in overhead athletes presents a unique set of challenges for both diagnosis and treatment. Although a great deal of attention has been focused on the management of injuries to the biceps-labrum complex and rotator cuff in throwers, comparatively less has been written about posterior glenohumeral instability within this unique cohort. Historically, posterior instability has been observed secondary to either acute trauma or repetitive microtrauma, usually among collision athletes, weight lifters, and rowers. However, posterior glenohumeral instability resulting from pathology of the posterior capsulolabral tissues in throwers is a different entity, and the clinical assessment begins with an accurate differentiation between adaptive capsular laxity and labral injury with pathologic instability. Some posterior capsule labrum tears confirmed on arthroscopy will require nothing more than débridement. However, for more extensive lesions, surgical treatment must balance the necessity to repair torn capsulolabral tissues with the tendency to over constrain the shoulder. The literature provides mixed results regarding the likelihood of overhead athletes with posterior glenohumeral instability and labral injury treated surgically returning to their preinjury level of sport performance.

NO DIFFERENCES IN HIP RANGE OF MOTION EXISTS BETWEEN BASEBALL PLAYERS WITH AN ULNAR COLLATERAL LIGAMENT TEAR AND HEALTHY BASEBALL PLAYERS.

BACKGROUND AND PURPOSE: Restrictions in hip rotational motion of the baseball athlete can alter throwing mechanics in a manner that is inefficient and increases risk of injury. The purpose of this study was to assess for differences in hip external rotation (ER) and internal rotation (IR) range of motion (ROM) between baseball players with an ulnar collateral ligament (UCL) tear and healthy baseball players. DESIGN: Case-control. METHODS: Eighty-seven baseball players with a UCL tear (UCL) were compared with 87 age, experience, and position-matched healthy baseball players (CONT). UCL were enrolled at the initial visit to the outpatient sports medicine facility while CONT were measured before their baseball season. Passive hip ROM (ER and IR) of the stance and lead limbs was measured in the prone position using a bubble goniometer. Hip total range of motion (TRM) was calculated by adding ER and IR of each limb. Independent t-tests were run to compare mean group differences for hip ROM (p<0.05). RESULTS: No differences between groups were discovered for hip ER on the stance (UCL = 33.9 °±9.9 °, CONT = 34.3 °±10.6 °, p = 0.8) or lead (UCL = 32.9 °±9.9 °, CONT = 34.4 °±10.0 °, p = 0.3) limbs. Similarly, there were no group differences in hip IR on the stance (UCL = 30.6 °±10.5 °, CONT = 29.6 °±9.5 °, p = 0.5) or lead (UCL = 33.5 °±17.5 °, CONT = 29.5 °±9.0 °, p = 0.1) limbs. The groups were also similar in hip TRM on the stance (UCL = 64.5 °±13.7 °, CONT = 64.0 °±17.2 °, p = 0.8) and lead (UCL = 66.4 °±17.4 °, CONT = 63.9 °±15.6 °, p = 0.3) limbs. CONCLUSIONS: When measured in the prone position, hip passive ROM is not different between baseball players with a UCL tear compared to a matched healthy cohort. LEVEL OF EVIDENCE: Level 3.

BASEBALL PLAYERS DIAGNOSED WITH ULNAR COLLATERAL LIGAMENT TEARS DEMONSTRATE GREATER SIDE TO SIDE DIFFERENCES IN PASSIVE GLENOHUMERAL ABDUCTION RANGE OF MOTION COMPARED TO HEALTHY CONTROLS.

BACKGROUND: Numerous studies have shown that baseball players develop range of motion adaptations in their throwing arm. While some of these shoulder range of motion adaptations can lead to greater throwing velocity, excessive changes in shoulder range of motion can increase the risk of injury to the ulnar collateral ligament (UCL). PURPOSE/HYPOTHESES: The purpose of this study was to compare the passive GH-ABD ROM measures of baseball players with a diagnosed UCL tear (UCL group) to a group of age, activity, and position matched healthy controls (CONT group). The primary hypothesis was that baseball players with an UCL tear would have a greater loss of passive glenohumeral abduction range of motion in their throwing shoulder than healthy controls. A secondary hypothesis was that baseball players with an UCL tear would demonstrate similar glenohumeral abduction range of motion in their non-throwing arm and increased side-to-side glenohumeral abduction differences compared to the healthy cohort. STUDY DESIGN: Retrospective prospective case-control study. RESULTS: The UCL group had significantly greater glenohumeral abduction range of motion on their throwing shoulder (132.5 °±8.3 °) than the CONT group (120.19 °±11.2 °, p = 0.000). Similarly, the UCL group had increased glenohumeral abduction range of motion on their non-throwing shoulder (141.2 °±9.5 °) compared to the CONT group (124.1 °±11.4 °, p = 0.000). Additionally, the UCL group had a greater glenohumeral abduction difference (-8.7 °±8.4 °) than the CONT group (-3.8 °±7.7 °, p = 0.001). CONCLUSION: In contrast to the original hypotheses, high school and collegiate baseball players that sustained an UCL injury presented with greater glenohumeral abduction range of motion in both their throwing and non-throwing shoulders compared to healthy controls. However, the finding of greater side-to-side glenohumeral abduction range of motion deficits in the UCL group when compared to the matched healthy controls confirms the secondary hypothesis. LEVEL OF EVIDENCE: Level 3.

Ligand Controlled Ir-Catalyzed Regiodivergent Oxyamination of Unactivated Alkenes.

An intramolecular Ir(III)-catalyzed regiodivergent oxyamination of unactivated alkenes provides valuable γ-lactams, γ-lactones and δ-lactams. The regioselectivity is controlled by the electronically tunable cyclopentadienyl Ir(III)-complexes enabling oxyamination via either 5-exo or 6-endo pathways. With respect to the mechanism, we propose a highly reactive [3.1.0] bicycle intermediate derived from Ir(V) nitrene-mediated aziridination to be a key intermediate toward the synthesis of γ-lactams.