Brian J. Sennett

Dynamic Measurements of Three-Dimensional Scapular Kinematics: A Validation Study

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.

The epidemiologic, pathologic, biomechanical, and cinematographic analysis of football-induced cervical spine trauma

Epidemiologic, pathologic, biomechanical, and cinema tographic data on head and neck injuries occurring in tackle football have been compiled since 1971 by the National Football Head and Neck Injury Registry. Pre liminary 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 Associa tions (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.

Spear tackler's spine An entity precluding participation in tackle football and collision activities that expose the cervical spine to axial energy inputs

We describe spear tacklers spine, a clinical entity that constitutes an absolute contraindication to participation in tackle football and other collision activities that ex pose 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 roentgen ograms obtained in the neutral position; 3) concomitant preexisting posttraumatic roentgenographic abnormal ities 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 authors practice, 15 cases of spear tacklers spine were identified during 1987 to 1990. All 15 cases were evaluated because of complaints referable to the cervical spine or brachial plexus result ing from football injuries. Of these, 11 had complete neurologic recovery without permanent sequelae. Four cases resulted in permanent neurologic deficits: quad riplegia, 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 tech niques. We suggest that individuals who possess the aforementioned characteristics of spear tacklers spine be precluded from participation in collision activities that expose the cervical spine to axial energy inputs.

Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

Background Ulnar collateral ligament reconstruction is commonly performed in major league pitchers, but little is known about pitching performance after a return to major league play. Hypothesis Pitching performance after ulnar collateral ligament reconstruction returns to baseline by the second season after surgery. Study Design Cohort study (prognosis); Level of evidence, 2. Methods Data were reviewed for 68 major league pitchers who pitched in at least 1 major league game before undergoing ulnar collateral ligament reconstruction between 1998 and 2003. Mean innings pitched per season, earned run average, and walks and hits per inning pitched were compared for each major league pitcher before and after surgery. All demographic and performance variables were analyzed for an association with ulnar collateral ligament insufficiency and a successful return to major league play. Results Fifty-six (82%) pitchers returned to major league play at a mean of 18.5 months after surgery with no significant change in mean earned run average or walks and hits per inning pitched. The mean innings pitched per season was not statistically different from controls by the second season after surgery. Starting pitchers demonstrated a higher risk of ulnar collateral ligament injury requiring reconstruction. More experienced pitchers and those with a higher earned run average were less likely to require ulnar collateral ligament reconstruction. No factors predictive of a successful return to play were identified. Conclusion Most major league pitchers return from ulnar collateral ligament reconstruction by the second season after surgery with no statistical change in mean innings pitched, earned run average, or walks and hits per inning pitched from preinjury levels.

The axial load teardrop fracture: A biomechanical, clinical, and roentgenographic analysis

The anteroinferior cervical vertebral body corner frac ture 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 se quelae, specifically quadriplegia. Axial loading of the cervical spine was clearly identified as a mechanism of injury for both fracture patterns. Roentgenographic ex amination 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.

Normative Sf-36 Values in Competing Ncaa Intercollegiate Athletes Differ from Values in the General Population

BACKGROUNDnThe Short Form-36 (SF-36) is a valid and reliable generic indicator of health status. The scoring distributions for the general and specific populations have been extensively reported in the literature and vary according to age, gender, the type and severity of a medical condition, and socioeconomic status. However, normative data pertaining specifically to athletic populations are limited. The purpose of the present study was to establish SF-36 reference norms for athletes cleared for participation in intercollegiate sports.nnnMETHODSnSix hundred and ninety-six United States National Collegiate Athletic Association Division-I and II student athletes who had been cleared for participation in intercollegiate sports completed the self-administered form of the SF-36 at the time of pre-participation evaluations. Demographic information and history of injuries were also recorded.nnnRESULTSnCompared with the general population and an age-matched sample of the general population, the athletes scored significantly higher in all health domains (p < 0.01) except for bodily pain (p = 0.05). Among the athletes, men scored significantly higher than women in the general health domain only (p = 0.0006). Athletes with no reported history of injury scored significantly higher than those with previous injuries in all health domains, except in role limitations due to emotional problems.nnnCONCLUSIONSnIntercollegiate athletes cleared for participation reported significantly higher SF-36 scores in comparison with a similarly aged sample of the general population. These normative values are important in the evaluation of health status of intercollegiate athletes before and after intervention.

Axial loading injuries to the middle cervical spine segment: An analysis and classification of twenty-five cases

Injuries to the cervical spine at the C3-C4 level involving the bony elements, intervertebral disks, and ligamen tous structures are rare. We present 25 cases of trau matic 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 le sions appear to be unique with regard to the infre quency of bony fracture, difficulty in effecting and main taining reduction, and a more favorable recovery follow ing 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 hernia tion (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 inter vertebral disc herniations are frequently associated with transient quadriplegia; 3) reduction of anterior sublux ation 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 manip ulation 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 unilat eral facet dislocation reduced within 3 hours of injury and subsequently fused anteriorly, significant neuro logic 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.

The pathomechanics and pathophysiology of cervical spinal cord injury

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.

Methicillin-resistant Staphylococcus aureus infections in collegiate football players.

PURPOSEnMethicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a serious skin infection in the athletic population. Literature in reference to football players has been sparse. We sought to better elucidate circumstances surrounding such infections in collegiate football players.nnnMETHODSnData from three Division-I collegiate football programs were consolidated and analyzed. Variables included presence of MRSA infection, timing of occurrence, body location involved, lesion morphology, need for surgical treatment, and antibiotic route. Data were analyzed statistically to evaluate player position, body location, and timing of occurrences.nnnRESULTSnOf the 491 collegiate football players, 33 (6.7%) were diagnosed with MRSA infections. Cutaneous manifestations included abscess (70%), cellulitis (16%), folliculitis, impetigo, and necrotizing fasciitis. Of the infections, 90% underwent surgical drainage, whereas 27% received intravenous antibiotics. Extremity infections (n = 30) greatly exceeded truncal infections (n = 7); the most common locations were the elbow (n = 11), knee (n = 6), leg (n = 4), and forearm (n = 4). There was no difference in occurrence by player position. Infections occurred predominantly in the first third of the season (P < 0.001, chi-square test) and significantly decreased as the season progressed.nnnCONCLUSIONnMRSA infections involving football players are becoming more common. This study documents player positions involved, timing of occurrence in the season, location and type of infections, and required treatment. Exposed extremities may predispose to infection due to risk for minor trauma and direct contact with bacteria. As infection risk seems to be independent of position, all players should observe protective measures. Although most infections occur earlier in the season, physicians should remain alert for infection occurrences throughout the season.

Athletic performance outcomes following lumbar discectomy in professional basketball players.

Study Design. Retrospective case-control study. Objective. To quantify the athletic performance profiles after lumbar discectomy (LD) in a cohort of National Basketball Association (NBA) players in comparison with a control group of matched NBA players who did not undergo LD during the same study period. Summary of Background Data. LD provides symptomatic relief and improved functional outcomes in the majority of patients as assessed by validated measures such as Oswestry Disability Index, Visual Analog Scale, and Short Form-36 (SF-36). Among professional athletes, however, the goal of lumbar HNP treated by discectomy is not only to improve functional status but also, ultimately, to return the player to preinjury athletic performance levels. No study to date has compared the athletic performance profiles before and after discectomy in professional athletes. Methods. An analysis of NBA games summaries, weekly injury reports, player profiles, and press releases was performed to identify 24 NBA players who underwent LD for symptomatic lumbar HNP between 1991 and 2007. A 1:2 case: control study was performed using players without history of lumbar HNP who were matched for age, position, experience, and body mass index as control subjects (n = 48). Paired t tests were conducted on the following parameters: games played, minutes per game, points per 40 minutes, rebounds per 40 minutes, assists per 40 minutes, steals per 40 minutes, blocks per 40 minutes, and shooting percentage. For each athletic performance outcome, between-group comparisons evaluating preindex to postindex season performance were done (index season = season of surgery). Results. In the LD group, 18 of 24 players (75%) returned to play again in the NBA, compared with 42 of 48 players (88%, P = 0.31) in the control group. One year after surgery, between-group comparisons revealed statistically significant increase in blocked shots per 40 minutes in the LD (0.18) versus control group (−0.33; P = 0.008) and a smaller decrease in rebounds per 40 minutes in the LD (−0.25) versus control group (−1.42; P = 0.049). No other performance variable was found to be significantly different between the study and control group. Conclusion. Compared with a closely matched control cohort, we found that 75% of surgical patients returned to play again in the NBA, compared with 88% in control subjects who did not undergo surgery. For those players who returned, overall athletic performance was slightly improved or no worse than control subjects.