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A key to the analysis of function after total hip replacement (THR) is the ability to identify gait adaptations specific to design features and surgical procedures. In a randomised controlled design, we evaluated the mechanics of gait after THR with a hip resurfacing system or conventional prosthesis. We also investigated whether gait adaptations returned to normal postoperatively. Similar improvements in mechanics of gait were found, except for peak abductor moments, which improved more in the conventional group. Gait speed increased significantly, but with no differences between groups. The increase in walking speed was reflected as significant improvement within groups in most kinematic and kinetic variables. Significant differences between the operated and non-operated hip were seen in all patients, but with no difference between groups. Mean curves of joint angle profiles and moments in all anatomical planes during a gait cycle revealed that gait impairment persisted with no differences between the conventional prosthesis and the resurfacing system.

Background and Purpose: Limited research suggests that an effect of whole body vibration (WBV) on the central nervous system (CNS) is suppression. An indirect measure used to assess CNS level of activation is the Soleus H-reflex. If true suppression does occur, other factors such as range of motion may be impacted. The purpose of this study was to examine the impact of WBV on H-reflex amplitude and passive ankle dorsiflexion., Subjects and Methods: Twenty-seven healthy volunteers between the ages of 21-41 participated. Subjects were randomly assigned to a control group (n=13) or WBV group (n=14). H-reflex and ankle dorsiflexion measures were assessed before and after a three minute WBV perturbation (40 μHz, amplitude 2-4 mm). These measurements were repeated every five minutes up to twenty minutes following the intervention., Results: The H-reflex amplitude showed a significant decrease (p<.05) between pre-test and initial post-test for both groups. The H-reflex returned to baseline within five minutes following the intervention. The dorsiflexion range of motion showed significant interaction (p<.05). All changes were less than 5 degrees; therefore, no clear clinical impact was evident., Conclusions: The observed decrease in H-reflex amplitude immediately following WBV agreed with previous research indicating a lower level of CNS activation. However, since the control group also showed this change, WBV does not appear to be a key cause of suppression. Range of motion was not clinically significant for either group.

The influence of pedaling frequency and crank load on the sensitivity of the soleus short latency stretch reflex (SLR) was examined in nine healthy subjects during pedaling by the use of a custom-built robotic actuator. The SLR decreased successively in downstroke when pedaling frequency increased from 20 to 40 and 60 revolutions per minute at a constant crank load (p = .005). The SLR was unchanged at crank load increases of 2.6 or 5.1 Nm at a constant pedaling frequency (p > .05). Accordingly, it was shown that increased muscle activation level as a consequence of added crank load and increased movement speed does not increase the sensitivity of the soleus SLR.

Objective: To present a clinical understanding of the role the scapula plays in the mechanics of shoulder function and specialized techniques for the rehabilitation of injuries around the shoulder girdle., Background: The scapular musculature is often neglected in the evaluation and treatment of shoulder injuries. This lack of attention often degenerates into the incomplete evaluation and rehabilitation of scapular dysfunction. Dysfunction or weakness of the scapular stabilizers often results in altered biomechanics of the shoulder girdle. The altered biomechanics can result in (1) abnormal stresses to the anterior capsular structures, (2) the increased possibility of rotator cuff compression, and (3) decreased performance., Description: We review the anatomy and role of the scapula, the pathomechanics of injury and dysfunction, and the evaluation and rehabilitation of the scapula. CLINICAL ADVANTAGE: Knowledge of how the scapular muscles influence function at the shoulder builds a strong foundation for the clinician to develop rehabilitation programs for the shoulder.

The treatment of focal full thickness articular defects in the knee has continued to present a challenge, with no traditional treatment method providing consistent acceptable long-term clinical results. Patients with significant chondral defects frequently have persistent joint line pain, swelling, and catching in the knee. In contrast to marrow stimulation treatment techniques, such as abrasion arthroplasty, drilling, or microfracture which populate the defect with pluripotential stem cells, the use of cultured autologous chondrocytes fills the defect with cells of a committed pathway to develop hyaline-like cartilage. This hyaline-like cartilage more closely recreates the wear characteristics and durability of normal hyaline cartilage than the fibrous or fibrocartilage repair tissue formed by pluripotential stem cells. The purpose of this paper is to review the efficacy of available treatment options as well as the basic science rationale, indications, technique, postoperative rehabilitation, and clinical results of using cultured autologous chondrocytes in the treatment of focal full thickness chondral defects of the knee.

Current concepts in postoperative anterior cruciate ligament (ACL) reconstruction management include participation in an "accelerated" rehabilitation program. There are no published reports examining the effects of accelerated or conservative rehabilitation on subjects with generalized ligamentous hyperelasticity. The purpose of this case study was to examine the effects of a conservative or "decelerated" rehabilitation program on the functional outcome of a hyperelastic female adolescent athlete following ACL reconstruction. The subject was a 15-year-old female basketball player who sustained a unilateral ACL tear and underwent subsequent ACL reconstruction using a patellar tendon autograft. The subject immediately began participation in a "decelerated" rehabilitation program in which the intensity and rate of progression was decelerated, emphasizing a prolonged period of maximum graft protection. Progress was objectively quantified with a battery of diagnosis-specific tests at scheduled intervals. Results at 52 weeks postoperative revealed normal range of motion, proprioception, balance, knee stability, quadriceps strength, hamstring strength, and subjective assessment values, and only a 4.0% deficit in functional scores. Our results suggest a "decelerated" rehabilitation program may be appropriate for the population with generalized ligamentous hyperelasticity by yielding excellent functional results without compromising the integrity of the graft and, ultimately, knee stability.

Knee joint effusion has been shown to cause a reflex inhibition of the quadriceps musculature. However, the effect of effusion on knee joint proprioception has not been thoroughly investigated. This issue is further clouded by the debate surrounding the role of the muscle spindle and joint mechanoreceptors in providing afferent feedback to the central nervous system. This case study examines the effects of a chronic effusion on knee joint proprioception. Possible suggestions for the results are discussed, and areas for further study are offered.

It is hypothesized that proprioceptive information plays an important role in joint stabilization and that muscle fatigue may alter proprioceptive ability. The purpose of this study was to determine what effect shoulder muscle fatigue has on glenohumeral proprioception and to examine the relationship between arm dominance and shoulder proprioception. Eighty subjects without a history of glenohumeral pathology participated. Each was seated on an isokinetic dynamometer with a randomly selected shoulder positioned in 90 degrees of abduction and elbow flexion. With vision blinded, the arm was passively positioned in 75 degrees of external rotation for 10 seconds, then passively returned to the neutral starting position. Three trials each of active and passive repositioning (2 degrees/sec) were recorded. Following a fatigue protocol, both active and passive repositioning were reassessed. Testing order was randomized. A significant difference was detected between pre- and post-fatigue scores. No significant difference was detected between dominant and nondominant extremities. No relationship between arm dominance and shoulder proprioception was established. It is concluded that shoulder proprioception is diminished in the presence of shoulder muscle fatigue, suggesting clinical rehabilitation protocols must emphasize increasing muscular endurance.

Methods for quantifying deficits in proprioceptive feedback need to be examined. The purpose of this study was to compare two protocols measuring hamstring reaction time. Forty subjects, 13 males and 27 females, between 21 and 31 years of age (means = 24.3, SD = 2.04) were tested bilaterally on the Kin-Com isokinetic dynamometer with simultaneous use of the KC-EMG electromyograph. Subjects were instructed to maximally contract their hamstring musculature in response to a sudden lever arm movement. The peak torque time (PTT) protocol quantified the time lapse between initial lever arm movement and the generation of maximum torque. The electromyograph time (EMGT) protocol measured the time lapse between initial lever arm movement and initial myoelectrical activity of the hamstring musculature. Both PTT and EMGT were found to be reliable (Cronbach alpha 0.823-0.896), with no significant difference (p < .05) between dominant and nondominant limbs. These results indicate that PTT and EMGT are effective for quantifying hamstring reaction time and that the uninvolved lower extremity may be used as a control.

The scapular musculature is often neglected in designing a rehabilitation protocol for the shoulder. Weakness of the scapular stabilizers and resultant altered biomechanics could result in: 1) abnormal stresses to the anterior capsular structures of the shoulder, 2) increased possibility of rotator cuff compression, and 3) decreased performance. This article presents known facts about the biomechanics of the scapula and surrounding muscles and suggests methods for evaluation of scapular muscle weakness. Exercise techniques to maximally strengthen the scapular musculature are also described. As our ability to document strength of these muscles improves, we will be able to determine the effect of scapular strengthening on improving symptoms related to impingement and instability. Scapular strengthening exercises are usually nonstressful to the rotator cuff and are easily implemented into a rehabilitation program for the shoulder.

Enhanced athletic performance emphasizes the muscle's ability to exert maximal force output in a minimal amount of time. Exaggerated maximal muscular force develops due to athletic movements producing a repeated series of stretch-shortening cycles. The stretch-shortening cycle occurs when elastic loading, through an eccentric muscular contraction, is followed by a burst of concentric muscular contraction. A form of exercise called plyometrics employs a quick, powerful movement involving a prestretch of the muscle, followed by a shortening, concentric muscular contraction, thus utilizing the stretch-shortening muscular cycle. The literature contains numerous references to plyometric training for the lower extremity, but there is a lack of information on the upper extremity plyometric program. Overhead activities, such as throwing, necessitate elastic loading to produce maximal, explosive, concentric muscular contractions. Plyometric exercise employs the concept of the stretch-shortening muscular cycle. The rehabilitation concept of specificity of training suggests plyometric exercise drills should be performed by the throwing athlete. This paper discusses the basic neurophysiological science and theoretical basis for plyometric exercise, and it describes an upper extremity stretch-shortening exercise program for the throwing athlete.

Reflex response times of the vastus medialis obliquus and vastus lateralis were evaluated in 41 normal subjects and 16 patients with extensor mechanism dysfunction. The reflex response times for both muscles to a patellar tendon tap were evaluated by electromyography. The latencies of the muscles were statistically analyzed in both groups. In normal subjects, one-tailed paired-sample t-tests determined that the vastus medialis obliquus fired significantly faster than the vastus lateralis (P less than 0.001). In the patients, the vastus lateralis fired significantly faster than the vastus medialis obliquus (P less than 0.001). A chi square goodness of fit test demonstrated a dependency between the order of muscle firing and the type of subject (P less than 0.001). Two-tailed independent-sample t-tests revealed that the patients demonstrated a significantly faster vastus lateralis response time than the normal subjects (P less than 0.001), whereas the vastus medialis obliquus times were not significantly different. This increase in vastus lateralis reflex response time may indicate a motor control problem in the patient with extensor mechanism dysfunction. Results indicate that there is a reversal of the normal muscular firing order between the two muscles in these patients. Patients with extensor mechanism dysfunction may be demonstrating a neurophysiologic motor control imbalance that may account for or contribute to their anterior knee pain.

'Metamorphosis' is a group of computer programs designed to permit rapid three-dimensional analysis and generation of models of nuclei cells from digitized data. Infinite exterior views are possible using the rotation program and the user has the added ability to enter the object and peer out. This permits analysis of structural associations from any perspective. Since many chromosome associations cannot be abstracted without a computer, using rotation and cluster analysis reveals obscure relationships. This concept becomes important when proposing theories involving interactions between two or more objects. The program is written in BASICA and designed for use on IBM-compatible personal computers equipped with a digitizer. Three-dimensional transformations are accomplished via matrix manipulation which permits rapid generation of new images.