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  • Author: Freddie H. Fu x
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Marc R. Safran, George L. Caldwell Jr. and Freddie H. Fu

The role of surgery in proprioception, and the current role of proprioception in surgery, is unclear due to the lack of scientific research and clinical studies. The main components of proprioception in surgery are viewed to be preservation of afferents, promotion of regeneration of mechanoreceptors, and modification of protective reflex arcs in the postoperative patient. Soft tissue tension is hypothesized to be important in the efficiency of proprioceptors. Further, postoperative rehabilitation concentrating on proprioception may improve the results of surgery. With better understanding by clinicians, proprioception may play a bigger role in surgical technique, prosthetic replacement choice, and even indications for surgery. Further, proprioceptive testing may help determine the time course for optimal functional outcome following procedures. Thus, the future for proprioception in surgery and clinical application is expanding rapidly.

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Scott M. Lephart, Mininder S. Kocher, Freddie H. Fu, Paul A. Borsa and Christopher D. Harner

Injury to the anterior cruciate ligament (ACL) is thought to disrupt joint afferent sensation and result in proprioceptive deficits. This investigation examined proprioception following ACL reconstruction. Using a proprioceptive testing device designed for this study, kinesthetic awareness was assessed by measuring the threshold to detect passive motion in 12 active patients, who were 11 to 26 months post-ACL reconstruction, using arthroscopic patellar tendon autograft (n=6) or allograft (n=6) techniques. Results revealed significantly decreased kinesthetic awareness in the ACL reconstructed knee versus the uninvolved knee at the near-terminal range of motion and enhanced kinesthetic awareness in the ACL reconstructed knee with the use of a neoprene orthotic. Kinesthesia was enhanced in the near-terminal range of motion for both the ACL reconstructed knee and the contralateral uninvolved knee. No significant between-group differences were observed with autograft and allograft techniques.

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Timothy J. Henry, Scott M. Lephart, Jorge Giraldo, David Stone and Freddie H. Fu

Context:

Muscle fatigue is an important concept in regard to the muscle function of the shoulder joint. Its effect on the muscle force couples of the glenohumeral joint has not been fully identified.

Objective:

To examine the effects of muscle fatigue on muscle force-couple activation in the normal shoulder.

Design:

Pretest, posttest.

Patients:

Ten male subjects, age 18–30 years, with no previous history of shoulder problems.

Main Outcome Measures:

EMG (area) values were assessed for the anterior and middle deltoid, subscapularis, and infraspinatus muscles during 4 dynamic stabilizing exercises before and after muscle fatigue. The exercises examined were a push-up, horizontal abduction, segmental stabilization, and rotational movement on a slide board.

Results:

No significant differences were observed for any of the muscles tested.

Conclusions:

The results of our study indicate that force-couple coactivation of the glenohumeral joint is not significantly altered after muscle fatigue.

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Gloria M. Beim, Jorge L. Giraldo, Danny M. Pincivero, Matthew J. Borror and Freddie H. Fu

The purpose of this study was to compare electromyographic (EMG) activity of the abdominal muscles between the crunch exercise and five other popular abdominal exercises. Surface EMG recordings of four muscles (upper rectus, lower rectus, external oblique, and internal oblique) of the anterior abdominal wall were collected and analyzed on 20 healthy, male volunteers. EMG activity was recorded during execution of the abdominal crunch, the sit-up, and exercises performed with the Abflex machine, the AbRoller, the Nordic Track Ab Works, and the Nautilus crunch machine. The results indicate that the crunch exercise is comparable to the five other abdominal exercises with respect to muscle activation of the internal and external abdominal oblique muscles. Activation of the upper rectus abdominal muscles appears to be best achieved with the Abflex machine, whereas the crunch exercise is superior to the sit-up for activation of the upper and lower rectus abdominal muscles.

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C. Buz Swanik, Scott M. Lephart, Frank P. Giannantonio and Freddie H. Fu

Anterior cruciate ligament (ACL) injury disrupts static and dynamic knee restraints, compromising functional stability. Deafferentation of ACL mechan-oreceptors alters the spinal reflex pathways to motor nerves and muscle spindles in addition to the cortical pathways for conscious and unconscious appreciation of proprioception and kinesthesia. These pathways are required by the feed-forward and feedback neuromuscular control systems to dynamically stabilize joints. Feed-forward motor control is responsible for preparatory muscle activity, while feedback motor control regulates reactive muscle activity. The level of muscle activation, preparatory or reactive, influences muscular stiffness, thereby providing dynamic restraint for the ACL-deficient athlete. Rehabilitation protocols should incorporate activities that enhance muscle stiffness while encouraging adaptations to peripheral afferents, spinal reflexes, and cortical motor patterns. Four elements crucial for reestablishing neuromuscular control and functional stability are proprioceptive and kinesthetic awareness, dynamic stability, preparatory and reactive muscle characteristics, and conscious and unconscious functional motor patterns.

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James J. Irrgang, Christopher D. Harner, Freddie H. Fu, Mark B. Silbey and Robbie DiGiacomo

The purpose of this study was to determine the effects of preoperative, intraoperative, and postoperative intervention on the incidence of loss of motion (LOM) following ACL reconstruction. A retrospective review of patients undergoing ACL reconstruction between 1990 and 1991 was conducted to identify those with LOM. Factors potentially related to loss of motion were recorded. The results were compared to the findings of a similar group of patients who underwent ACL reconstruction between 1987 and 1989. In 1990 to 1991, less concomitant ligament surgery was performed, the incidence of loss of extension was significantly reduced, and the incidence of loss of flexion was significantly increased. It appears the risk for loss of extension can be minimized by delaying surgery following acute injury, performing less concomitant ligament surgery, paying meticulous attention to notchplasty and anatomic placement of the graft, and placing early emphasis on restoration of full extension following surgery.

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Marc R. Safran, Christopher D. Harner, Jorge L. Giraldo, Scott M. Lephart, Paul A. Borsa and Freddie H. Fu

Proprioceptive deficits have been demonstrated following anterior cruciate ligament (ACL) disruption, but little research exists evaluating proprioception in the posterior cruciate ligament (PCL)-deficient and/or -reconstructed knee. We have studied proprioception in PCL-deficient and PCL-reconstructed knees. The following summarizes our protocol and results of proprioceptive testing of kinesthesia and joint position sense in participants with isolated PCL injuries and those who underwent PCL reconstruction. We studied 18 participants with isolated raptures of the PCL and 10 participants who underwent PCL reconstruction. Proprioception was evaluated by two tests: the threshold to detect passive motion (TTDPM) and the ability to passively reproduce passive positioning (RPP). These assess kinesthesia and joint position sense, respectively. We have shown that isolated PCL deficiency in the human knee does result in reduced kinesthesia and enhanced joint position sense. Thus, the proprioceptive mechanoreceptors in the PCL do appear to have some function. We further found that PCL reconstruction significantly improved kinesthesia at 45° of knee flexion, while 110° was not significantly different between the involved and uninvolved knee in both studies.