Intersession Reliability of Hoffmann Reflex Gain and Presynaptic Inhibition in the Human Soleus Muscle

Hayes BT, Hicks-Little CA, Harter RA, Widrick JJ, Hoffman MA. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle.

Objective

To determine the day-to-day reliability of Hoffmann reflex (H-reflex) gain and presynaptic inhibition of spinal reflexes in the human soleus muscle.

Design

Controlled trial.

Setting

Research laboratory.

Participants

Volunteers (N=30; mean ± SD age, 23.4±3.9y; height, 175.64±10.87cm; mass, 84.50±24.18kg) with no history of lower extremity pathology and/or injury participated.

Interventions

Subjects lay prone with the head, shoulders, arms, and hips supported in a static position by a massage body pillow and the ankle positioned at 90°. Recording electrodes were placed over the soleus and tibialis anterior muscle bellies, and the stimulating electrodes were positioned over the tibial nerve in the popliteal space and the common peroneal nerve near the fibular head.

Main Outcome Measures

The H-reflex and motor wave recruitment curves were then measured and recorded. Presynaptic inhibition was also assessed in the soleus muscle, and a conditioning stimulation of the common peroneal nerve (1 × motor threshold = motor threshold) was used prior to soleus H-reflex measurement. Two testing sessions took place between 2 and 7 days, and each session occurred at the same time of day.

Results

Assessments of H-reflex gain and presynaptic inhibition yielded test-retest reliability of R equal to . 95 and .91, respectively.

Conclusions

Measures of presynaptic inhibition and H-reflex gain (H slope/M slope) in the human soleus muscle are consistent and reliable day to day.     

Mechanical Instability After an Acute Lateral Ankle Sprain

Hubbard TJ, Cordova M. Mechanical instability after an acute lateral ankle sprain.

Objective

To examine the natural recovery of mechanical laxity after an ankle sprain over an 8-week period.

Design

Prospective cohort study.

Setting

Biodynamics research laboratory.

Participants

Subjects with an acute lateral ankle sprain (n=16; 7 men, 9 women; age, 19.5±0.7y; mass, 64.6±8.1kg; height, 171.9±9.6cm) and healthy controls (n=16; 7 men, 9 women; age, 20.4±1.7y; mass, 76.9±11.1kg; height, 176.5±11.1cm) participated.

Interventions

Not applicable.

Main Outcome Measures

Subjects with acute ankle sprains were tested 3 days after injury and again 8 weeks later. Anterior and posterior displacement (mm) and inversion and eversion rotation (°) were measured with an instrumented arthrometer. For each dependent variable, a 2 × 2 × 2 repeated-measures multivariate analysis of variance was performed.

Results

A significant interaction was found between group, time, and side for anterior translation (F=4.24, P=.05). There were also significant main effects for group. There was significantly more anterior displacement at day 3 (F=19.52, P=.001) and at week 8 (F=8.45, P=.010) in the injured group compared with the healthy group. There was also significantly more inversion rotation at day 3 (F=2.70, P=.002) and at week 8 (F=5.4, P=.033) in the injured group compared with the healthy group.

Conclusions

The lack of significant differences in mechanical laxity over an 8-week period suggests that natural recovery of laxity takes longer than 8 weeks. Further research needs to be conducted to examine how long this laxity persists and the role ankle rehabilitation plays in mechanical stability restoration.     

A Critical Analysis of Dudley Morton’s Concept of Disordered Foot Function

The name Morton is associated with a foot structure characterized by a short first metatarsal in comparison with the adjacent second metatarsal. Dudley Morton is credited with recognizing a short first metatarsal as being a primary defect of the foot. Morton, an anatomist, approached his observation from an evolutionary perspective. His theory of disordered foot function was based on the premise that human alignment centered on an "axis of leverage" and around an "axis of balance." Morton concluded that the presence of a short first metatarsal was compounded when the first metatarsal segment was hypermobile. Shortness and hypermobility diminished the capacity of the first metatarsal segment to carry weight, allowed pronation during activity, and led to an overload of the central metatarsals. The term Morton Foot sprang from his teachings. The extensive writings of Morton are commonly cited even today. This study compares Morton's teachings with research published during the last 70 years, which either supports or refutes his claims.     

Exertional heat stroke in competitive athletes

Exertional heat stroke (EHS) is a serious medical condition that can have a tragic outcome if proper assessment and treatment are not initiated rapidly. This article focuses on critical misconceptions that pertain to the prevention, recognition, and treatment of EHS, including 1) the randomness of EHS cases, 2) the role of nutritional supplements in EHS, 3) temperature assessment, 4) onset of EHS and the possible lucid interval, 5) rapid cooling, and 6) return to play. Exploration of these topics will enhance the medical care regarding EHS.     

Sports related mild traumatic brain injury in adolescents

While head injuries are not common in youth sports, they may have catastrophic results. Concussion is also referred to as mild traumatic brain injury (MTBI). Although the occurrence of head injuries has been studied more extensively in American football, the findings have wider application for any MTBI. Recently, more attention has been directed at other sports in which both boys and girls participate. The diagnosis of MTBI is based on subjective findings and subtle changes in mental status. Other cerebral injuries requiring emergent or urgent neurosurgical attention should be ruled out. Objective tests such as CT scans and Magnetic Resonsance Imaging (MRI) are usually without significant findings in MTBI. Neuropsychological testing may demonstrate areas of deficiencies, however, results may be difficult to interpret because of confounding factors. Complications following MTBI have been known to occur. The most catastrophic of these is second impact syndrome. There are a variety of guidelines for return to play following a concussion, which have been designed in an effort to avoid problems such as second impact syndrome. These guidelines are based more on clinical experience than on scientific evidence. Education, good training and coaching techniques, improved equipment, and rule changes and enforcement, can all help in curbing the sports related head injuries in adolescents.     

Commonalities, Differences, and Challenges With Patient-derived Outcome Measurement Tools: Function/Activity Scales

Background

There is a critical need to evaluate the success of orthopaedic treatments through valid outcome measures. Previous attempts to express patient outcomes using a single aggregate score led to scores that were ambiguous, often insensitive to change, and poorly correlated with the patient’s assessment of the outcome of surgical procedures.

Where Are We Now?

Numerous patient-reported outcome measurement tools have been developed for assessment of patients’ level of activity and functional status, especially after joint arthroplasty. However, most tools assume an idealized set of prescribed activities independent of the age, activity level, and lifestyle of each individual. Few instruments are designed to capture the priorities of individual patients, especially those involved in high-demand sporting and recreational activities.

Where Do We Need to Go?

We need valid outcome measures that provide a meaningful, individualized assessment of the functional status of each patient, taking into account the lifestyle and expectation of each individual. This advance in outcome measurement will allow clinicians to individualize treatment and provide patients with an accurate estimate of the outcome of alternative treatments and procedures.

How Do We Get There?

Much more comprehensive information is needed to characterize the activities, abilities, and physical aspirations of individual patients. This could form a database for the development of predictive models relating individual characteristics to functional outcomes. Statistical tools are needed to minimize the burden on patients in completing questionnaires to access predictive data and to ensure that all outcome assessments are psychometrically valid.     

Treatment of shoulder pain in thesenior athlete

As our population ages, seniors participating in sports or fitness programs are being seen more frequently in orthopedic practices for the complaint of shoulder pain. While evaluation and treatment of the senior athlete is similar to evaluation and treatment of the younger athlete, the senior cohort presents some specific challenges. Diagnosis is more difficult: underlying disease processes including cervical spondylosis, cardiac and neoplastic diseases are more common. Physical examination is important, because magnetic resonance scans may present many abnormalities not all of which are symptomatic. We reserve magnetic resonance scanning for patients in whom the diagnosis is in question, or for those who fail conservative measures. Surgical treatment is complicated by the quality of tissue to repair. Proper rehabilitation, for both nonsurgical and operative treatment is essential and should be physician directed. Finally, many senior athletes have unrealistic expectations of treatment underscoring the need, for good patient-physician communication.     

Screening for catastrophic neck injuries in sports

The cervical spine is prone to injury due to the structure of the articulating vertebrae at the level of C4-C6, where the spinal cord occupies more of the spinal canal. Cervical spine injuries can occur in all sports and all ages. Participation in contact sports certainly increases the possibility of cervical spine injuries. In screening for catastrophic neck injuries it is vital to examine incidence and injury surveillance statistics in sports. These data can help determine sport-specific preponderance of catastrophic injury. Screening methods for predisposition to catastrophic cervical spine injuries include a concise history, physical examination, and radiographic methods. There is currently no universal classification system utilizing imaging of the cervical spine that has been validated as a screening method for catastrophic neck injuries.