The Ulnar Olecranon-Coronoid Notch Angle Affects Terminal Elbow Extension in Children and Adolescents.

BACKGROUND: Limitations to terminal elbow extension (TEE) in pediatric populations have been commonly associated with the degree of ligamentous laxity and not bony factors. Ligamentous laxity, quantified through the Beighton score, is criticized for unreliably assessing joint mobility. This study aims to show that the olecranon-coronoid notch angle (OCNA) affects TEE in healthy children and adolescents. METHODS: A retrospective study of 711 pediatric patients treated for upper extremity and shoulder injuries was cross-sectionally studied at 2 tertiary centers from 2014 to 2021. Radiographs were used to measure the OCNA, humerocondylar angle, proximal anterior ulnar angle, and the presence of secondary centers of ossification. A 2-axis goniometer measured clinical TEE to a firm endpoint. The statistical analysis studied the relationships between OCNA and TEE and the effect that age and sex have on these measurements. RESULTS: Increased TEE was associated with increased OCNA (P<0.001) when accounting for age and sex. The average OCNA was 30.0 degrees (7.5 degrees), and the average TEE was 5.6 degrees (8.0 degrees). There was a difference in OCNA between subjects who had elbow hypoextension, normal TEE, and elbow hyperextension (P<0.001). The most common injuries were distal radius fractures (182, 26%), elbow sprains and contusions (111, 16%), distal both bone forearm fractures (95, 14%), single or both bone shaft fractures (77, 11%), and supracondylar fractures (74, 11%). CONCLUSION: These results show that the orientation of the opening of the olecranon-coronoid notch influences the arc of TEE motion in a healthy pediatric population. The notch restrains TEE by activating the bony block mechanism between the olecranon apophysis and the olecranon fossa. The measurement of the OCNA can serve as a reproducible and quantitative method to predict hypomobility to hypermobility of TEE motion. LEVEL OF EVIDENCE: Prognostic study: Level II.

Compound Motor Action Potentials During a Modest Nerve Crush.

Nerve crush injury results in axonotmesis, characterized by disruption of axons and their myelin sheaths with relative sparing of the nerve's connective tissue. Despite the widespread use of crush injury models, no standardized method for producing these lesions has been established. We characterize a crush model in which a narrow forceps is used to induce a modest and controlled compressive injury. The instantaneous compound motor action potential (CMAP) is monitored in situ and in real-time, allowing the characterization of neuromuscular response during and after injury. The tibial nerves of 11 anesthetized rats were surgically isolated. After the placement of electrodes, CMAPs were elicited and registered using a modular-data-acquisition system. Dumont-#5 micro-forceps were instrumented with a force transducer allowing force measurement via a digital sensor. Baseline CMAPs were recorded prior to crush and continued for the duration of the experiment. Nerve crushing commenced by gradually increasing the force applied to the forceps. At a target decrease in CMAP amplitude of 70%-90%, crushing was halted. CMAPs were continually recorded for 5-20 min after the termination of the crushing event. Nerves were then fixed for histological assessment. The following post-crush mean values from 19 trials were reported: peak CMAP amplitude decreased by 81.6% from baseline, duration of crush was 17 sec, rate of applied force was 0.03 N/sec, and maximal applied force was 0.5 N. A variety of agonal phenomena were evident post-lesion. Following the initial decrease in CMAP, 8 of 19 trials demonstrated a partial and transient recovery, followed by a further decline. Thirteen trials exhibited a CMAP amplitude near zero at the end of the recording. Twelve trials demonstrated a superimposed EMG background response during and after the crush event, with disappearance occurring within 4-8 min. Qualitative histology assessment at the lesion site demonstrated a correspondence between CMAP response and partial sparing of nerve fibers. By using a targeted decline in CMAP amplitude as the endpoint, researchers may be able to produce controlled, brief, and reproducible crush injuries. This model can also be used to test interventions aimed at enhancing subsequent regeneration and behavioral recovery.

Motion capture evaluation of sagittal spino-pelvic biomechanics after lumbar spinal fusion.

PURPOSE: The spine and pelvis coexist as a dynamic linked system in which spinal and pelvic parameters are correlated. Investigation of this system can inform the understanding and treatment of spinal deformity. Here, we demonstrate the use of motion capture technology to measure spine biomechanical parameters using a novel testing apparatus. METHODS: Three complete cadaveric spines with skull and pelvis were mounted into a biomechanical testing apparatus. Each lumbar vertebra was monitored by motion capture cameras as the spines underwent maximal anterior and posterior pelvic tilts about two sagittal axes at a controlled speed and applied force. These axes were defined as the sacral axis which passes transversely through the ilium and S1, and the acetabular axis which passes transversely through both acetabula. The experiments were repeated after L4-L5 fusion, and then, after both L4-L5 and T12-S1 fusion with pedicle screw instrumentation. Data were collected for total range of motion and for coupled translation at each functional spinal unit (FSU). RESULTS: Total range of motion and coupled translation within functional spinal units (FSUs) was decreased after spinal fusion. The displacement of each individual FSU was captured and summarized along with the observed patterns under each experimental condition. CONCLUSION: Lumbar fusion decreases spinal motion in the sagittal plane in both overall ROM and individual coupled translations of lumbar vertebrae. This was demonstrated using motion capture technology which is useful for quantifying the translations of individual FSUs in a multisegmental spinal model.

Abnormal Coagulation as a Risk Factor for Postoperative Complications After Primary and Revision Total Hip and Total Knee Arthroplasty.

BACKGROUND: Patients undergoing total joint arthroplasty (TJA) have an increased likelihood of having an abnormal coagulation profile compared with the general population. Coagulation abnormalities are often screened for before surgery and considered during perioperative planning. This study assesses a preoperative abnormal coagulation profile as a risk factor for postoperative complications after total hip arthroplasty (THA), revision THA (rTHA), total knee arthroplasty (TKA), and revision TKA (rTKA) and then examines specific coagulopathies to determine their influence on complication rates. METHODS: Patients who underwent THA, rTHA, TKA, or rTKA from 2011 to 2017 were identified in the American College of Surgeons National Surgical Quality Improvement Program database and then assessed for preoperative abnormal coagulation profiles. Various postoperative complications were analyzed for each cohort, and two separate multivariate regression analyses were used to assess the relationship between abnormal coagulation and postoperative complications. RESULTS: 403,566 THA, rTHA, TKA, or rTKA cases were identified, and 40,466 (10.0%) of patients were found to have an abnormal coagulation profile. Patients with preoperative coagulation abnormalities had higher likelihoods of postoperative complications after primary TJA than in revision TJA. An international normalized ratio>1.2 was associated with the most types of postoperative complications, followed by a bleeding disorder diagnosis. A partial thromboplastin time>35 seconds was associated with only one type of postoperative complication, while a platelet count <150,000 per µL was associated with postoperative complications only after TKA. CONCLUSION: TJA in patients with abnormal coagulation profiles may result in adverse outcomes. These patients may benefit from preoperative intervention. Prophylactic care needs to be personalized to the specific coagulation abnormalities present.

Role of Depression in Total Knee Arthroplasty: A Retrospective Analysis of Perioperative Outcomes in Patients in the United States.

We evaluate the patient demographics, perioperative outcomes, in-hospital complications, and assess recent national trends in clinically depressed and non-depressed patients undergoing primary total knee arthroplasty (TKA). Using the National Hospital Discharge Survey from 2001 and 2010, patients undergoing primary TKA in the United States were identified based upon the diagnosis of depression. Differences in gender, patient-demographics, comorbidities, complications, length of stay, and discharge disposition were analyzed. A total of 32,761 TKA patients were identified, consisting of 1,880 patients with a diagnosis of depression and 30,881 patients without. The depression group had an average age significantly younger than the non-depression cohort (p < 0.01). The depression group contained a significantly greater percentage of females when compared to the non-depression group. The non-depression group had a significantly greater percentage of African-Americans (p < 0.01), and a significantly smaller percentage of Caucasians (p < 0.01). Our findings contribute to the literature on the role of depression on perioperative outcomes of TKA. (Journal of Surgical Orthopaedic Advances 30(1):007-009, 2021).

Evaluation of A2 and A4 Hand Pulley Repair Using Tendon Graft Rings.

PURPOSE: To compare the mechanical characteristics of A2 and combined A2-A4 pulley repair in the intact and damaged flexor pulley system. METHODS: After control testing, we recorded tendon excursion and flexion of 11 cadaveric fingers after several interventions: (1) complete excision of A2 and A4, (2) repair of the A2 with one ring of tendon graft, (3) repair of the A2 with 2 rings of tendon graft, and (4) repair of the A2 with 2 rings combined with repair the A4 with one ring. RESULTS: At the proximal interphalangeal (PIP) joint, the maximum rotational angle decreased by an average of 30% after complete excision of the A2 and A4 pulleys. This angle was still decreased compared with the control by an average of 25% after one-ring repair at A2, 23% after 2-ring repair at A2, and 17% after 2-ring repair at A2 combined with one-ring repair at A4. At the metacarpophalangeal joint, the average maximum rotational angle decreased by an average of 17% after complete excision of the A2 and A4 pulleys. This angle was still decreased compared with the control by an average of 11% after one-ring repair at A2, 7% after 2-ring repair at A2, and 4% after 2-ring repair at A2 combined with one-ring repair at A4. Kinematic behavior at the PIP joint with an intact pulley system was most closely approximated by the 3-loop repair. The least similar behavior was with a 2-ring construct at A2. CONCLUSIONS: All repairs increased average flexion at the PIP and metacarpophalangeal joints compared with the unrepaired samples. The 3-ring configuration exhibited a higher recovery of PIP flexion compared with the other repairs. CLINICAL RELEVANCE: Although each repair restored flexion, clinical studies are necessary to evaluate the clinical relevance of the mechanical results of this study.

The use of laryngeal mask airway for adenoidectomy.

OBJECTIVES: Airway management during adenoidectomy is traditionally performed through endotracheal intubation (ETT). Laryngeal mask airway (LMA) may be less stimulating to the airway and allow for shorter overall operating room time. Previous studies report LMA use during adenotonsillectomy. There has been no prior evaluation of LMA use during adenoidectomy alone. In this study, we attempt to identify the rate and contributing factors of LMA failure during adenoidectomy. METHODS: All pediatric patients undergoing adenoidectomy between January 1, 2016 and June 30, 2017 were reviewed. Demographic and clinical data were collected and analyzed to determine the need for conversion to ETT and the occurrence of any complications. RESULTS: Our study revealed 139 pediatric patients who underwent adenoidectomy during the study period. 110 patients had adenoidectomy performed with LMA and 27 patients had ETT. Two patients (1.8%) required conversion to ETT because of difficulty with ventilation when the mouth gag was in place. There were no complications. Mean operating room time was 20 min less in the LMA group (P < 0.05). CONCLUSIONS: The use of an LMA in adenoidectomy may be a safe and effective alternative to ETT. More study is required to determine overall complication rates.

A Parallel-Plate Flow Chamber for Mechanical Characterization of Endothelial Cells Exposed to Laminar Shear Stress.

Shear stresses induced by laminar fluid flow are essential to properly recapitulate the physiological microenvironment experienced by endothelial cells (ECs). ECs respond to these stresses via mechanotransduction by modulating their phenotype and biomechanical characteristics, which can be characterized by Atomic Force Microscopy (AFM). Parallel Plate Flow Chambers (PPFCs) apply unidirectional laminar fluid flow to EC monolayers in vitro. Since ECs in sealed PPFCs are inaccessible to AFM probes, cone-and-plate viscometers (CPs) are commonly used to apply shear stress. This paper presents a comparison of the efficacies of both methods. Computational Fluid Dynamic simulation and validation testing using EC responses as a metric have indicated limitations in the use of CPs to apply laminar shear stress. Monolayers subjected to laminar fluid flow in a PPFC respond by increasing cortical stiffness, elongating, and aligning filamentous actin in the direction of fluid flow to a greater extent than CP devices. Limitations using CP devices to provide laminar flow across an EC monolayer suggest they are better suited when studying EC response for disturbed flow conditions. PPFC platforms allow for exposure of ECs to laminar fluid flow conditions, recapitulating cellular biomechanical behaviors, whereas CP platforms allow for mechanical characterization of ECs under secondary flow.