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We describe spear tackler's spine, a clinical entity that constitutes an absolute contraindication to participation in tackle football and other collision activities that expose the cervical spine to axial energy inputs. A subset of football players were identified who demonstrated: 1) developmental narrowing (stenosis) of the cervical canal; 2) persistent straightening or reversal of the normal cervical lordotic curve on erect lateral roentgenograms obtained in the neutral position; 3) concomitant preexisting posttraumatic roentgenographic abnormalities of the cervical spine; and 4) documentation of having employed spear tackling techniques. From data obtained by the National Football Head and Neck Injury Registry and the senior author's practice, 15 cases of spear tackler's spine were identified during 1987 to 1990. All 15 cases were evaluated because of complaints referable to the cervical spine or brachial plexus resulting from football injuries. Of these, 11 had complete neurologic recovery without permanent sequelae. Four cases resulted in permanent neurologic deficits: quadriplegia, 2; incomplete hemiplegia, 1; and residual long track signs, 1. Permanent neurologic injury occurred as the result of axial loading of a persistently straightened cervical spine from use of head-impact playing techniques. We suggest that individuals who possess the aforementioned characteristics of spear tackler's spine be precluded from participation in collision activities that expose the cervical spine to axial energy inputs. [ABSTRACT FROM AUTHOR]

The anteroinferior cervical vertebral body corner fracture was originally described by Schneider and Cann as the 'teardrop' fracture. This report analyzes the biomechanical, clinical, and roentgenographic features of 55 such fractures obtained from the National Football Head and Neck Injury Registry. Teardrop fractures resulting from tackle football characteristically occurred in players attempting to make a tackle in which initial contact was made with the top or crown of the helmet. There were two fracture patterns associated with the anteroinferior corner (teardrop) fracture fragment: 1) the isolated fracture, which is usually not associated with permanent neurologic sequelae; and 2) the three-part, two-plane fracture in which there is an associated sagittal vertebral body fracture as well as fracture of the posterior neural arch. This latter pattern was almost always associated with permanent neurologic sequelae, specifically quadriplegia. Axial loading of the cervical spine was clearly identified as a mechanism of injury for both fracture patterns. Roentgenographic examination must include both anteroposterior and lateral views with computed tomography or tomography as necessary to determine the presence of the sagittal vertebral body fracture and the integrity of the posterior neural arch. [ABSTRACT FROM AUTHOR]

Background: Health care delivery continues to evolve, with an effort being made to create patient-centered care models using patient-reported outcomes (PROs) data. Collecting PROs has remained challenging and an expanding landscape of digital health offers a variety of methods to engage patients., Objective: The aim of this study is to prospectively investigate two common methods of remote PRO data collection. The study sought to compare response and engagement rates for bidirectional SMS text messaging and mobile surveys following orthopedic surgery., Methods: The study was a prospective, block randomized trial of adults undergoing elective orthopedic procedures over 6 weeks. The primary objective was to determine if the method of digital patient engagement would impact response and completion rates. The primary outcome was response rate and total completion of PRO questionnaires., Results: A total of 127 participants were block randomized into receiving a mobile survey (n=63) delivered as a hyperlink or responding to the same questions through an automated bidirectional SMS text messaging system (n=64). Gender, age, number of comorbidities, and opioid prescriptions were similar across messaging arms. Patients receiving the mobile survey were more likely to have had a knee-related surgery (n=50, 83.3% vs n=40, 62.5%; P=.02) but less likely to have had an invasive procedure (n=26, 41.3% vs n=39, 60.9%; P=.03). Overall engagement over the immediate postoperative period was similar. Prolonged engagement for patients taking opioids past postoperative day 4 was higher in the mobile survey arm at day 7 (18/19, 94.7% vs 9/16, 56.3%). Patients with more invasive procedures showed a trend toward being responsive at day 4 as compared to not responding (n=41, 59.4% vs n=24, 41.4%; P=.05)., Conclusions: As mobile patient engagement becomes more common in health care, testing the various options to engage patients to gather data is crucial to inform future care and research. We found that bidirectional SMS text messaging and mobile surveys were comparable in response and engagement rates; however, mobile surveys may trend toward higher response rates over longer periods of time., Trial Registration: ClinicalTrials.gov NCT03532256; https://clinicaltrials.gov/ct2/show/NCT03532256., (©Anish K Agarwal, Zarina S Ali, Frances Shofer, Ruiying Xiong, Jessica Hemmons, Evan Spencer, Dina Abdel-Rahman, Brian Sennett, Mucio K Delgado. Originally published in JMIR Formative Research (https://formative.jmir.org), 17.03.2022.)

Importance: Surgeons must balance management of acute postoperative pain with opioid stewardship. Patient-centered methods that immediately evaluate pain and opioid consumption can be used to guide prescribing and shared decision-making., Objective: To assess the difference between the number of opioid tablets prescribed and the self-reported number of tablets taken as well as self-reported pain intensity and ability to manage pain after orthopedic and urologic procedures with use of an automated text messaging system., Design, Setting, and Participants: This quality improvement study was conducted at a large, urban academic health care system in Pennsylvania. Adult patients (aged ≥18 years) who underwent orthopedic and urologic procedures and received postoperative prescriptions for opioids were included. Data were collected prospectively using automated text messaging until postoperative day 28, from May 1 to December 31, 2019., Main Outcomes and Measures: The primary outcome was the difference between the number of opioid tablets prescribed and the patient-reported number of tablets taken (in oxycodone 5-mg tablet equivalents). Secondary outcomes were self-reported pain intensity (on a scale of 0-10, with 10 being the highest level of pain) and ability to manage pain (on a scale of 0-10, with 10 representing very able to control pain) after orthopedic and urologic procedures., Results: Of the 919 study participants, 742 (80.7%) underwent orthopedic procedures and 177 (19.2%) underwent urologic procedures. Among those who underwent orthopedic procedures, 384 (51.8%) were women, 491 (66.7%) were White, and the median age was 48 years (interquartile range [IQR], 32-61 years); 514 (69.8%) had an outpatient procedure. Among those who underwent urologic procedures, 145 (84.8%) were men, 138 (80.7%) were White, and the median age was 56 years (IQR, 40-67 years); 106 (62%) had an outpatient procedure. The mean (SD) pain score on day 4 after orthopedic procedures was 4.72 (2.54), with a mean (SD) change by day 21 of -0.40 (1.91). The mean (SD) ability to manage pain score on day 4 was 7.32 (2.59), with a mean (SD) change of -0.80 (2.72) by day 21. The mean (SD) pain score on day 4 after urologic procedures was 3.48 (2.43), with a mean (SD) change by day 21 of -1.50 (2.12). The mean (SD) ability to manage pain score on day 4 was 7.34 (2.81), with a mean (SD) change of 0.80 (1.75) by day 14. The median quantity of opioids prescribed for patients who underwent orthopedic procedures was high compared with self-reported consumption (20 tablets [IQR, 15-30 tablets] vs 6 tablets used [IQR, 0-14 tablets]), similar to findings for patients who underwent urologic procedures (7 tablets [IQR, 5-10 tablets] vs 1 tablet used [IQR, 0-4 tablets]). Over the study period, 9452 of 15 581 total tablets prescribed (60.7%) were unused. A total of 589 patients (64.1%) used less than half of the amount prescribed, and 256 patients (27.8%) did not use any opioids (179 [24.1%] who underwent orthopedic procedures and 77 [43.5%] who underwent urologic procedures)., Conclusions and Relevance: In this quality improvement study of adult patients reporting use of opioids after common orthopedic and urologic surgical procedures through a text messaging system, the quantities of opioids prescribed and the quantity consumed differed. Patient-reported data collected through text messaging may support clinicians in tailoring prescriptions and guide shared decision-making to limit excess quantities of prescribed opioids.

Background: Analysis of upper extremity weight bearing ability is important for athletes as some function largely in a closed chain capacity (e.g., wrestling, football, gymnastics); also, all require closed chain upper extremity function during strength and conditioning. Additionally, in a rehabilitation setting, closed chain upper extremity functional testing is often used as a return to play criterion. Lower extremity sway measures (biomechanical and clinical) have been published widely and have established reliability and validity; however, the reliability of upper extremity sway biomechanical measures has not been investigated to date., Hypothesis/purpose: The purpose of this study was to determine the repeatability of a variety of force plate measurements during an upper extremity task in an athletic population. It was hypothesized that variables measuring upper extremity sway in a closed kinetic chain position would have excellent reliability., Study Design: Cross-sectional., Methods: All data were collected using a force plate system with commercially available software. Four hundred and ninety healthy Division I athletes were tested for both their dominant and non-dominant upper extremity at one of two testing sessions. Subjects were instructed to stay as still as possible while maintaining a full plank position with one upper extremity on the force plate and the contralateral upper extremity behind their back. Two, 20-second trials were performed for each extremity. Variables measured included average sway velocity (ASV), sway velocity in medial-lateral (SVML) and anterior-posterior (SVAP) directions, sway velocity at 1 st and 2 nd time intervals for AP (VAP1 and 2) and ML (VML1 and 2) directions, and sway frequency in the AP direction for 1 st and 2 nd time intervals (FreAP1 and 2). Intraclass correlation coefficients (ICC (2,1) ) and their 95% confident intervals were calculated for all force plate variables for 980 limbs., Results: No difference was seen between left and right extremities for any measure ( p  > 0.05). ICC's ranged from 0.61-0.90 for all variables, indicating moderate to excellent reliability for all variables., Conclusion: Upper extremity sway biomechanical variables using a force plate system have moderate to excellent reliability. These results are important prior to validation and clinical utilization of these measures including baseline testing, return to play guidelines, and injury prevention parameters., Level of Evidence: 3., (© 2020 by the Sports Physical Therapy Section.)

Objective: It has been established that most patients prescribed opioids after minor surgery have tablets left over, better understanding the variation in opioid prescribing and variation in dosage of the prescription could guide efforts to reduce prescribing. This study describes the state-level variation in opioid prescribing after a knee arthroscopy among opioid-naïve patients., Design: Retrospective cohort study., Setting: Commercial insurance claims data., Participants: 98 623 individual across the USA with commercial insurance who were opioid-naïve and had a knee arthroscopy between 2015 and 2019., Exposure: Patients who filled an opioid prescription within 3 days of a knee arthroscopy., Outcome Measures: Opioid prescriptions were measured as a pharmacy claim for filling an opioid within 3 days of a knee arthroscopy. We measured the patient and state-level opioid prescribing rate, tablet count, morphine milligram equivalent dose per prescription and risk-adjusted predicted opioid quantity., Results: Overall, 72% of patients filled an opioid prescription with a median tablet count of 40 and median morphine milligram equivalent of 250. Patients with an invasive procedure (27.9% vs 22.4%; p<0.001), higher education level (p<0.001) and fewer comorbidities (0.9 vs 1.2, p<0.001) had higher rates of opioid prescribing. The prescribing rate in the highest state, Nebraska (85%), was double the prescribing rate in the lowest state, South Dakota (40%). Comparing the casemix adjusted expected prescribing rate to the observed prescribing rate displayed that 18 states had observed prescribing rates that were higher than their expected prescribing rates., Conclusion: Wide variation in the likelihood of receiving a prescription, depending on state of residence, was observed. The dosages prescribed were high and have been associated with transition to long-term use. These findings suggest that there is substantial opportunity for the development of guidelines to reduce variability in opioid prescribing for this common ambulatory procedure., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The kinetic chain theory is widely used as a rationale for the inclusion of core stability training in athletes. Core stability (muscle capacity and neuromuscular control) impairments may result in less than optimal performance and abnormal force dissipation to the shoulder complex that could lead to shoulder injuries. However, a paucity of literature exists to support this relationship, and no previous studies have investigated the relationship between isolated core neuromuscular control and shoulder injuries. Additionally, lower extremity postural stability has been associated with athletic function and may also be associated with shoulder injuries. The purpose of this study was to compare biomechanical measures of isolated core neuromuscular control and lower extremity postural stability between athletes with and without non-traumatic shoulder injuries., Methods: Eighty athletes (55 males, age: 21.2 ± 3.3 years, 40 with a current shoulder injury) completed biomechanical measures of isolated core neuromuscular control and lower extremity postural stability. Athletes were matched by age, gender, body mass index, and sport type. MANOVAs were used to assess differences between measures of core neuromuscular control and lower extremity postural stability between groups., Findings: There were no statistically significant differences between athletes with and without shoulder injuries for the static core neuromuscular control measures, F(4,75) = 0.45, P = 0.78, η 2  = 0.02; dynamic core neuromuscular control measures, F(4,75) = 0.81, P = 0.52, η 2  = 0.04; or lower extremity postural stability measures, F(8,61) = 0.85, P = 0.56, η 2  = 0.10., Interpretation: Although core stability is widely incorporated in rehabilitation of athletes with shoulder injuries, athletes with current non-traumatic shoulder injuries may not present with impairments in core neuromuscular control or lower extremity postural stability., (Copyright © 2019. Published by Elsevier Ltd.)

There continues to be a high incidence of shoulder injuries in throwing athletes, with sometimes disappointing return-to-play outcomes, creating an increased need to understand the pathophysiology of the injury and to better characterize the injury during the clinical examination. Current concepts suggest that the disabled throwing shoulder is a useful construct to develop a more comprehensive view of the complex local and distant musculoskeletal alterations that can be seen associated with the clinical symptoms. The pathophysiology can be seen as a cascade to injury, in which proximal or distal deficits in motion, strength, and strength balance can affect force production, joint position, and joint loads throughout the kinetic chain. Local imbalances between force production and load can create anatomic injury or create distant imbalances that create the injury. The evaluation then becomes a more comprehensive one, necessitating a look at all areas of the kinetic chain and evaluation of them in the context of the requirements on the structures during each of the phases of the throwing motion. Specific testing for core stability, scapular stability and motion, and local muscle strength, strength balance, and flexibility needs to be performed, as well as tests for tissue injury.

Background: Relationships between core stability and lower extremity injuries have been described in the literature; however, evidence of the relationship between upper extremity injuries and core stability and balance is limited., Hypothesis/purpose: The purpose of this study was to compare clinical measures of core stability and balance between athletes with and without non-traumatic shoulder injuries., Study Design: Cross sectional., Methods: Eighty athletes (54 males, age: 21.2 + 3.3 years) participated in this study. Forty athletes with a current shoulder injury were matched to healthy athletes by age, gender, BMI, and sport. Athletes completed clinical core stability tests including flexor and extensor endurance tests, double leg lower test (°) and balance tests including single leg stance under eyes open and eyes closed conditions, and the Y-balance test. MANOVAs were used to assess group differences., Results: No statistically significant differences existed between athletes with and without shoulder injuries for clinical tests of core stability, F(1,78)=0.97, p=0.41; η2 = 0.04. No statistically significant differences existed between injured athletes with and without shoulder injuries for static and dynamic balance measures, F(1,78)=0.86, p=0.53; η2 = 0.07., Conclusions: Although core stability is widely incorporated in rehabilitation of athletes with shoulder injuries, performance on these clinical tests did not differ in the group of athletes assessed in this study., Level of Evidence: 3.

Background: Few studies have examined acute injuries in track and field in both elite and subelite athletes., Purpose: To observe the absolute number and relative rates of injury in track and field athletes across a wide range of competition levels and ages during 3 years of the Penn Relays Carnival to assist with future medical coverage planning and injury prevention strategies., Study Design: Descriptive epidemiology study., Methods: Over a 3-year period, all injuries treated by the medical staff were recorded on a standardized injury report form. Absolute number of injuries and relative injury rates (number of injuries per 1000 competing athletes) were determined and odds ratios (ORs) of injury rates were calculated between sexes, competition levels, and events. Injuries were also broken down into major or minor medical or orthopaedic injuries., Results: Throughout the study period, 48,473 competing athletes participated in the Penn Relays Carnival, and 436 injuries were sustained. For medical coverage purposes, the relative rate of injury subtypes was greatest for minor orthopaedic injuries (5.71 injuries per 1000 participants), followed by minor medical injuries (3.42 injuries per 1000 participants), major medical injuries (0.69 injuries per 1000 participants), and major orthopaedic injuries (0.18 injuries per 1000 participants). College/elite athletes displayed the lowest relative injury rate (7.99 injuries per 1000 participants), which was significantly less than that of high school (9.87 injuries per 1000 participants) and masters athletes (16.33 injuries per 1000 participants). Male athletes displayed a greater likelihood of having a minor orthopaedic injury compared with female athletes (OR, 1.36 [95% CI, 1.06-1.75]; χ2 = 5.73; P = .017) but were less likely to sustain a major medical injury (OR, 0.33 [95% CI, 0.15-0.75]; χ2 = 7.75; P = .005). Of the 3 most heavily participated in events, the 4 × 400-m relay displayed the greatest relative injury rate (13.6 injuries per 1000 participants) compared with the 4 × 100-m and 4 × 200-m relays., Conclusion: Medical coverage teams for future large-scale track and field events need to plan for at least 2 major orthopaedic and 7 major medical injuries per 10,000 participants. Male track and field athletes, particularly masters male athletes, are at greater risk of injury compared with other sexes and competition levels., (© 2015 The Author(s).)

Objective: Concussion, defined as an impulse blow to the head or body resulting in transient neurologic signs or symptoms, has received increasing attention in sports at all levels. The King-Devick (K-D) test is based on the time to perform rapid number naming and captures eye movements and other correlates of suboptimal brain function. In a study of boxers and mixed martial arts (MMA) fighters, the K-D test was shown to have high degrees of test-retest and inter-rater reliability and to be an accurate method for rapidly identifying boxers and mixed martial arts fighters with concussion. We performed a study of the K-D test as a rapid sideline screening tool in collegiate athletes to determine the effect of concussion on K-D scores compared to a pre-season baseline., Methods: In this longitudinal study, athletes from the University of Pennsylvania varsity football, sprint football, and women's and men's soccer and basketball teams underwent baseline K-D testing prior to the start of the 2010-11 playing season. Post-season testing was also performed. For athletes who had concussions during the season, K-D testing was administered immediately on the sidelines and changes in score from baseline were determined., Results: Among 219 athletes tested at baseline, post-season K-D scores were lower (better) than the best pre-season scores (35.1 vs. 37.9s, P=0.03, Wilcoxon signed-rank test), reflecting mild learning effects in the absence of concussion. For the 10 athletes who had concussions, K-D testing on the sidelines showed significant worsening from baseline (46.9 vs. 37.0s, P=0.009), with all except one athlete demonstrating worsening from baseline (median 5.9s)., Conclusion: This study of collegiate athletes provides initial evidence in support of the K-D test as a strong candidate rapid sideline visual screening tool for concussion. Data show worsening of scores following concussion, and ongoing follow-up in this study with additional concussion events and different athlete populations will further examine the effectiveness of the K-D test., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Purpose: The overall purpose of our study was to examine the sensitivity of physical examination, magnetic resonance imaging (MRI), and magnetic resonance (MR) arthrogram for the identification of arthroscopically confirmed SLAP lesions of the shoulder., Methods: An analysis of 51 consecutive patients with arthroscopically confirmed SLAP lesions and no history of shoulder dislocation was performed. Before undergoing surgery, all patients underwent a standardized physical examination and had either an MRI and/or MR arthrogram performed. Sensitivity analysis was then performed on the results of both the physical examination maneuvers and the radiologic imaging compared to the arthroscopic findings at surgery., Results: The sensitivity of O'Brien's (active compression) test was 90%, whereas the Mayo (dynamic) shear was 80% and Jobe's relocation test was 76%. The sensitivity of a physical examination with any 1 of these 3 SLAP provocative tests being positive was 100%. Neer's sign (41%) and Hawkin's impingement tests (31%) each had low sensitivity for SLAP lesions. The sensitivity of MRI for SLAP lesions was 67% when interpreted by the performing surgeon, 53% when read by a radiologist. When the MR arthrograms were analyzed alone, the sensitivity was 72% (surgeon) and 50% (radiologist), respectively., Conclusions: All 3 physical examination maneuvers traditionally considered provocative for SLAP pathology (O'Brien's, Mayo shear, and Jobe's relocation) were sensitive for the diagnosis of SLAP lesions. MRI and MR arthrogram imaging had lower sensitivity than these physical examination tests in diagnosing SLAP lesions. Patient history, demographics, and the surgeon's physical examination should remain central to the diagnosis of SLAP lesions., Level of Evidence: Level II, development of diagnostic criteria on basis of consecutive patients with universally applied gold standard.

The purpose of this study was to describe 3-dimensional scapular motion patterns during dynamic shoulder movements with the use of a direct technique. Direct measurement of active scapular motion was accomplished by insertion of 2 1.6-mm bone pins into the spine of the scapula in 8 healthy volunteers (5 men, 3 women). A small, 3-dimensional motion sensor was rigidly fixed to the scapular pins. Sensors were also attached to the thoracic spine (T3) with tape and to the humerus with a specially designed cuff. During active scapular plane elevation, the scapula upwardly rotated (mean [SD] = 50 degrees [4.8 degrees ]), tilted posteriorly around a medial-lateral axis (30 degrees [13.0 degrees ]), and externally rotated around a vertical axis (24 degrees [12.8 degrees ]). Lowering of the arm resulted in a reversal of these motions in a slightly different pattern. The mean ratio of glenohumeral to scapulothoracic motion was 1.7:1. Normal scapular motion consists of substantial rotations around 3 axes, not simply upward rotation. Understanding normal scapular motion may assist in the identification of abnormal motion associated with various shoulder disorders.

The validation of two noninvasive methods for measuring the dynamic three-dimensional kinematics of the human scapula with a magnetic tracking device is presented. One method consists of simply fixing a sensor directly to the acromion and the other consists of mounting a sensor to an adjustable plastic jig that fits over the scapular spine and acromion. The concurrent validity of both methods was assessed separately by comparison with data collected simultaneously from an invasive approach in which pins were drilled directly into the scapula. The differences between bone and skin based measurements represents an estimation of skin motion artifact. The average motion pattern of each surface method was similar to that measured by the invasive technique, especially below 120 degrees of elevation. These results indicate that with careful consideration, both methods may offer reasonably accurate representations of scapular motion that may be used to study shoulder pathologies and help develop computational models.

Study Design: Nonrandomized 2 group post-test only., Objective: To compare scapular position and orientation between subjects with and without impingement syndrome., Background: Abnormal scapular motion is commonly believed to be a contributing factor to shoulder impingement syndrome., Methods and Measures: Twenty nonimpaired subjects with a mean age of 34.3 (+/- 7.5 years) and 17 patients with impingement syndrome with a mean age of 45.8 (+/- 11.0) participated. A 3-dimensional electromechanical digitizer was used to measure scapular position and orientation in 3 planes. Measurements were taken with the arm at the side, elevated in the scapular plane to horizontal, and at maximum elevation. One-way analysis of variance was used to compare nonimpaired subjects to the impingement group and the symptomatic and asymptomatic sides within the impingement group. Five scapular kinematic variables were assessed at each arm position. Orientation was described by posterior tilting angle, upward rotation angle, and internal rotation angle. Position was described by medial-lateral position and superior-inferior position and determined by the distance from the scapula centroid to the seventh cervical vertebra (C7)., Results: During scapular plane elevation of the arm, the scapula showed a general pattern of increasing posterior-tilt angle, increasing upward-rotation angle, and decreasing internal-rotation angle in both impingement and nonimpaired groups. Also, the scapula moved to a more superior position and a slightly more medial position with increasing arm elevation. Compared to nonimpaired subjects (34.6 degrees +/- 9.7), those with impingement demonstrated a significantly lower posterior tilting angle of the scapula in the sagittal plane (25.1 degrees +/- 9.1). Subjects with impingement also demonstrated higher superior-inferior scapular position with maximal arm elevation (5.2 cm +/- 1.6 below the first thoracic vertebrae) compared to nonimpaired subjects (7.5 cm +/- 1.5)., Conclusions: These results suggest that altered scapular kinematics may be an important aspect of the impingement syndrome.

One hundred ten cases of the transient neurological phenomenon, cervical cord neurapraxia (CCN), are presented. The authors established a classification system for CCN, developed a new computerized measurement technique for magnetic resonance (MR) imaging, investigated the relationship of the cervical cord to the canal, and analyzed clinical, x-ray, and MR data. One hundred nine males and one female were included in the study; the average age of the participants was 21 years (range 13-33 years). All episodes occurred during sports participation; 87% occurred while the patient was playing football. Follow-up review lasting an average of 3.3 years was available for 105 patients (95%). Narrowing of the sagittal diameter of the cervical canal in the adult spine was confirmed to be a causative factor. Cervical cord neurapraxia was not associated with permanent neurological injury and no permanent morbidity occurred in patients who returned to contact activities. Of the patients returning to contact activities, 35 (56%) experienced a recurrent episode. The risk of recurrence was increased with smaller spinal canal/vertebral body ratio (p < 0.05), smaller disc-level canal diameter (p < 0.05), and less space available for the cord (p < 0.05). There was no correlation between either the classification of the CCN episode or the disease noted on MR imaging and x-ray films and the risk of recurrence. The authors conclude that: 1) CCN is a transient neurological phenomenon and individuals with uncomplicated CCN may be permitted to return to their previous activity without an increased risk of permanent neurological injury; 2) congenital or degenerative narrowing of the sagittal diameter of the cervical canal is a causative factor; 3) the overall recurrence rate after return to play is 56%; and 4) the risk of recurrence is strongly and inversely correlated with sagittal canal diameter and it is useful in the prediction of future episodes of CCN (p < 0.001). These data will enable the physician to counsel individuals regarding a predicted risk of recurrence based on canal measurements.

Studies of the passive support provided by ankle braces have focused primarily on inversion support. The goal of this study was to develop a technique to measure the support provided by ankle braces in all rotational directions and to use this technique to compare four common braces (Ascend, Swede-O, Aircast, and Active Ankle). For this purpose, a 6 degrees-of-freedom linkage was used to measure the flexibility of the ankle complex in 10 healthy subjects. Each subject was tested without brace support and with each of the four braces. Testing was repeated on each subject on two different occasions. The angular displacement at specified moment values and the four segmental flexibility values obtained from the loading portion of the moment-angular displacement data were used in the data analysis. Repeated measure analysis of variance followed by a Student Neuman-Keuls test at p < 0.05 was performed. This statistical analysis was used to identify significant differences among the braces and differences between each brace and the no brace condition. Each of the four braces provided significant support in inversion, eversion, and internal rotation, but the amount of support varied significantly among the braces. In external rotation, only the stirrup braces provided significant support. The braces also varied significantly in the amount of interference with dorsiflexion and plantar flexion. Clinicians may be assisted by objective data on the amount and nature of passive support when prescribing braces to their patients.

Cervical cord injuries caused during American football games have resulted in reversible, incompletely reversible, and irreversible neurologic deficits. An explanation for this variable response to injury has been obtained from the study of the histochemical responses of a squid axon injury model to mechanical deformation. Data obtained indicate that recovery or lack thereof is directly proportional to the intracellular calcium concentration which in turn is directly proportional to the amount and rate of tension applied to the axon. It is concluded that in most instances of acute spinal injury, disruption of cord function is a result of the effects of local cord anoxia and the increased concentration of intracellular calcium. It is proposed that implementation of therapeutic measures that restore blood flow and reduce cytosolic calcium will increase neurologic recovery.

Isolated newborn rat calvarial bone cells grown in monolayer on polyurethane membranes in specially constructed culture chambers and subjected to a cyclical biaxial mechanical strain of 0.17% at a frequency of 1 Hz for 30 min demonstrated a 16% increase in DNA synthesis during the subsequent 24 h. The metabolites of the inositol phosphate pathway, shown to be an important second messenger in many cell types, were shown to be elevated using high-performance liquid chromatography to separate and quantitate the various inositol polyphosphates. Inositol 1,4,5-trisphosphate, inositol 1,4-bisphosphate, and inositol 1,3,4,5-tetrakisphosphate reached peak accumulations after 20 s of mechanical strain. Inositol 1,3,4-trisphosphate reached a peak accumulation after 2 min, and inositol 1,2,3,4,5,6 phosphate reached a peak accumulation after 60 min of mechanical strain. Neomycin, an inhibitor of phospholipase C, a membrane-bound enzyme that hydrolyzes phosphatidyl inositol 4,5-bisphosphate to start the inositol phosphate cascade, completely inhibited accumulation of the above inositol phosphates during mechanical straining of the bone cells. Neomycin also completely abolished the increase in DNA synthesis that was seen after a mechanical strain of 0.17%. It is concluded from this study that the inositol phosphate pathway is activated by mechanical strain in bone cells and that this pathway is an important and primary mediator in the transduction of mechanical strain into cellular proliferation in these cells.

Injuries to the cervical spine at the C3-C4 level involving the bony elements, intervertebral disks, and ligamentous structures are rare. We present 25 cases of traumatic C3-C4 injuries sustained by young athletes and documented by the National Football Head and Neck Injury Registry. Review of the cases reveals that the response of energy inputs at the C3-C4 level differ from those involving the upper (C1-C2) and lower (C4-C5-C6-C7) cervical segments. Specifically, the C3-C4 lesions appear to be unique with regard to the infrequency of bony fracture, difficulty in effecting and maintaining reduction, and a more favorable recovery following early, aggressive treatment. In the majority of instances, injury at this level results from axial loading of the cervical spine. Lesions were distributed into specific categories: 1) acute intervertebral disc herniation (N = 4), 2) anterior subluxation of C3 on C4 (N = 4), 3) unilateral facet dislocation (N = 6), 4) bilateral facet dislocation (N = 7), and 5) fracture of vertebral body C4 (N = 4). Analysis of these 25 cases suggests that traumatic lesions of the cervical spine in general can be classified as involving the upper (C1-C2), middle (C3-C4), or lower (C4-C7) segments. This is based on our observations from this series that C3-C4 lesions 1) generally do not involve fracture of the bony elements; 2) acute intervertebral disc herniations are frequently associated with transient quadriplegia; 3) reduction of anterior subluxation of C3 on C4 is difficult to maintain; 4) reduction of unilateral facet dislocation is difficult to obtain by skeletal traction and is best managed by closed manipulation and reduction under general anesthesia; and 5) reduction of bilateral facet dislocation is difficult to obtain by skeletal traction and is best managed by open methods. The more favorable results observed in this series of immediate reduction of both unilateral and bilateral facet dislocations deserves emphasis. In two cases of unilateral facet dislocation reduced within 3 hours of injury and subsequently fused anteriorly, significant neurologic recovery occurred. The other four patients, two who underwent an open reduction and laminectomy and two treated closed with skeletal traction, remained quadriplegic. In the four instances of bilateral facet dislocation where reduction was achieved by either closed or open methods, although there was no neurologic recovery, all four patients survived their injuries. However, the three patients who were not successfully reduced died.

Forty-two consecutive patients with chronic osteomyelitis complicating persistent tibial nonunion and chronic osteomyelitis complicating tibial fracture with segmental bone loss were treated from January 1979 through December 1986 using a protocol including either open cancellous bone grafting (Friedlaender-Papineau technique), posterolateral bone grafting (Harmon technique), or local or microvascular soft-tissue transfer before cancellous bone grafting. Each patient had undergone surgical debridement and intravenous antibiotic therapy before inclusion in this study. Patients were classified using a staging system which included consideration of anatomic location of the infection within the bone; extent of bone involvement; quality of soft-tissue envelope and vascular integrity; and generalized host status. The overall success rate for arresting the osteomyelitis and healing the nonunion was 62% (26/42). If the six patients who refused additional bone graft surgery, the one patient who represented poor patient selection, and the patient who refused ankle arthrodesis are eliminated, the success rate for healing of the nonunion and resolving the osteomyelitis in this difficult patient population is: open bone cell graft, 66% (12/18); soft-tissue transfer 87.5%, (7/8); and posterolateral bone grafting, 87.5% (7/8). Use of a standardized classification system allows comparison of treatment results. Adequate debridement is crucial in treating osteomyelitis complicating established long bone fractures and nonunions. Determining the extent of debridement has proven to be the single most difficult aspect technically. Patient selection and pretreatment education are crucial. Caring for these patients is not only labor intensive and demanding of personnel and hospital resources, but demanding of the patients as well.

Epidemiologic, pathologic, biomechanical, and cinematographic data on head and neck injuries occurring in tackle football have been compiled since 1971 by the National Football Head and Neck Injury Registry. Preliminary analysis performed in 1975 indicated that the majority of serious cervical spine football injuries were caused by axial loading. Based on this observation, the National Collegiate Athletic Association (NCAA) and National Federation of High School Athletic Associations (NFHSAA) implemented rule changes banning "spearing" and the use of the top of the helmet as the initial point of contact in striking an opponent during a tackle or block. Between 1976 and 1987, as a result of these rule changes, the Registry has documented a dramatic decrease in both the total number of cervical spine injuries and those resulting in quadriplegia at both the high school and college level. It is suggested that development and implementation of similar preventative measures based on clearly defined injury mechanisms would decrease injury rates in diving, rugby, ice hockey, trampolining, wrestling, and other high-risk sports as well.

The traumatic C3-C4 level injuries sustained by young athletes and documented by the National Football Head and Neck Injury Registry are discussed. Twenty-eight of 885 (2.8 per cent) injuries involved the C3-C4 vertebrae. Review of these cases reveals that the response to energy inputs at the C3-C4 level differ from that of those involving the upper (C1-C2) and lower (C5-C6) cervical segments. Specifically, these lesions appear unique with regard to infrequency of bony fracture, difficulty in effecting and maintaining reduction, and their more favorable response to early aggressive treatment. It is the authors' belief that these lesions resulting from athletic activity are due to axial loading.

Data on cervical spine injuries resulting from participation in football have been compiled by a national registry. Analysis of epidemiologic data and cinematographic documentation clearly demonstrated that the majority of cervical fractures and dislocations were due to axial loading. On the basis of this observation, rule changes banning both deliberate "spearing" and the use of the top of the helmet as the initial point of contact in making a tackle were implemented at the high school and college level. Subsequently, a marked decrease in cervical spine injury rates has occurred. The occurrence of permanent cervical quadriplegia decreased from 34 in 1976 to five in the 1984 season. It is suggested that axial loading of the cervical spine is also responsible for the catastrophic injuries in diving, rugby, ice hockey, and gymnastics. Implementation of appropriate changes in playing techniques and/or equipment modifications could possibly reduce the incidence of cervical spine injuries in these activities.

The specter of catastrophic cervical neurotrauma resulting from athletic participation, although infrequent, has been consistently associated with football, water sports, gymnastics, rugby, and ice hockey. Injury involving intracranial hemorrhage can result in death or permanent neurologic impairment, whereas certain fractures and dislocations of the cervical spine are associated with quadriplegia. Athletic injuries to both the central nervous system and spinal cord demand our attention as an active area of clinical and basic injury. A review of the available literature reveals changing injury patterns as well as current concepts regarding the mechanism responsible for most athletic injuries to these structures. Accurate descriptions of the mechanism(s) responsible for a particular injury transcend simple academic interest. In order that preventive measures be implemented, the manner in which injury occurs must be accurately defined. The purpose of this article is to describe how the application of this principle resulted in the significant reduction of cervical spine injuries associated with quadriplegia that have occurred in tackle football since 1976.