Biomedical subjects

Kevin G Laudner

Publications and source records attributed to Kevin G Laudner.

5 recordsLinked to original sources

PubMed2006

Scapular dysfunction in throwers with pathologic internal impingement.

STUDY DESIGN: Case control group study. OBJECTIVES: To compare scapular position and orientation between baseball players with and without pathologic internal impingement. BACKGROUND: Scapular dysfunction has been implicated as a contributor to throwing-related pathologic internal impingement of the shoulder due to its role in increasing the contact between the greater tuberosity and posterior-superior glenoid, thereby impinging the posterior rotator cuff tendon(s) and labrum. However, to date, no definitive data demonstrate this scapular dysfunction in throwing athletes. The purpose of this study was to assess, in a controlled laboratory environment, whether scapular position and orientation would be different in throwing athletes diagnosed with pathologic internal impingement than in a control group of throwing athletes. METHODS AND MEASURES: Eleven throwing athletes diagnosed with pathologic internal impingement, using both clinical examination and a magnetic resonance arthrogram, were demographically matched with a control group of 11 throwers with no history of upper extremity injury. An electromagnetic tracking device was used to measure scapular internal/external rotation, anterior/posterior tilt, upward/downward rotation, sternoclavicular protraction/retraction, and elevation/depression during humeral elevation within the scapular plane. Comparisons were made between groups with analysis of variance models (P<.05). RESULTS: The individuals in the pathologic internal impingement group demonstrated statistically significant increased sternoclavicular elevation when elevating their humerus from 30 degrees to 120 degrees (P = .002) and from 60 degrees to 120 degrees (P = .003), compared to the control group. Furthermore, these patients also had increased posterior scapular tilt position (P = .016). No statistically significant differences were present in any other scapular variables measured. CONCLUSIONS: Based on the results of this study, throwing athletes diagnosed with pathologic internal impingement present with statistically significant increases in sternoclavicular elevation and scapular posterior tilt position during humeral elevation in the scapular plane.

Adult↗

PubMed2005

Glenohumeral range of motion deficits and posterior shoulder tightness in throwers with pathologic internal impingement.

BACKGROUND: Alterations in glenohumeral range of motion, including increased posterior shoulder tightness and glenohumeral internal rotation deficit that exceeds the accompanying external rotation gain, are suggested contributors to throwing-related shoulder injuries such as pathologic internal impingement. Yet these contributors have not been identified in throwers with internal impingement. HYPOTHESIS: Throwers with pathologic internal impingement will exhibit significantly increased posterior shoulder tightness and glenohumeral internal rotation deficit without significantly increased external rotation gain. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Eleven throwing athletes with pathologic internal impingement diagnosed using both clinical examination and a magnetic resonance arthrogram were demographically matched with 11 control throwers who had no history of upper extremity injury. Passive glenohumeral internal and external rotation were measured bilaterally with standard goniometry at 90 degrees of humeral abduction and elbow flexion. Bilateral differences in glenohumeral range of motion were used to calculate glenohumeral internal rotation deficit and external rotation gain. Posterior shoulder tightness was quantified as the bilateral difference in passive shoulder horizontal adduction with the scapula retracted and the shoulder at 90 degrees of elevation. Comparisons were made between groups with dependent t tests (P < .05). RESULTS: The throwing athletes with internal impingement demonstrated significantly greater glenohumeral internal rotation deficit (P = .03) and posterior shoulder tightness (P = .03) compared with the control subjects. No significant differences were observed in external rotation gain between groups (P = .16). CLINICAL RELEVANCE: These findings could indicate that a tightening of the posterior elements of the shoulder (capsule, rotator cuff) may contribute to impingement. The results suggest that management should include stretching to restore flexibility to the posterior shoulder.

Adult↗

PubMed2005

Neuromuscular and biomechanical adaptations of patients with isolated deficiency of the posterior cruciate ligament.

BACKGROUND: Functional adaptations of patients with posterior cruciate ligament deficiency (grade II) are largely unknown despite increased recognition of this injury. HYPOTHESIS: Posterior cruciate ligament-deficient subjects (grade II, 6- to 10-mm bilateral difference in posterior translation) will present with neuromuscular and biomechanical adaptations to overcome significant mechanical instability during gait and drop-landing tasks. STUDY DESIGN: Controlled laboratory study. METHODS: Bilateral comparisons were made among 10 posterior cruciate ligament-deficient subjects using radiographic, instrumented laxity, and range of motion examinations. Biomechanical and neuromuscular characteristics of the involved limb of the posterior cruciate ligament-deficient subjects were compared to their uninvolved limb and to 10 matched control subjects performing gait and drop-landing tasks. RESULTS: Radiographic (15.3 +/- 2.9 to 5.6 +/- 3.7 mm; P = .008) and instrumented laxity (6.3 +/- 2.0 to 1.4 +/- 0.5 mm; P < .001) examinations demonstrated significantly greater posterior displacement of the involved knee within the posterior cruciate ligament-deficient group. The posterior cruciate ligament-deficient group had a significantly decreased maximum knee valgus moment and greater vertical ground reaction force at midstance during gait compared to the control group. During vertical landings, the posterior cruciate ligament-deficient group demonstrated a significantly decreased vertical ground reaction force loading rate. All other analyses reported no significant differences within or between groups. CONCLUSION: Posterior cruciate ligament-deficient subjects demonstrate minimal biomechanical and neuromuscular differences despite significant clinical laxity. CLINICAL RELEVANCE: The findings of this study indicate that individuals with grade II posterior cruciate ligament injuries are able to perform gait and drop-landing activities similar to a control group without surgical intervention.

Adaptation, Physiological↗

PubMed2005

Scapular position and orientation in throwing athletes.

BACKGROUND: Despite the recognized importance of proper 3-dimensional motion of the scapula in throwers, minimal research has quantified scapular position and orientation in throwing athletes. HYPOTHESIS: Throwing athletes exhibit scapular position and orientation differences when compared to nonthrowing control subjects. STUDY DESIGN: Descriptive laboratory study. METHODS: Scapular position and orientation during scapular plane humeral elevation were assessed with electromagnetic tracking in a group of 21 throwing athletes and 21 control subjects. Scapular upward/downward rotation, internal/external rotation, anterior/posterior tipping, elevation/depression, and protraction/retraction were assessed. RESULTS: The throwing athletes demonstrated significantly increased upward rotation, internal rotation, and retraction of the scapula during humeral elevation. No differences in anterior/posterior tipping and elevation/depression were present. CONCLUSIONS: The results indicate that throwing athletes have scapular position and orientation differences compared to non-throwing athletes. This suggests that throwers develop chronic adaptation for more efficient performance of the throwing motion. CLINICAL RELEVANCE: Clinicians evaluate scapular position, orientation, and movement in throwing athletes as part of the evaluation of shoulder injuries associated with the throwing motion. The current study provides clinicians with an understanding of the types of adaptations that may be observed in normal, healthy throwing athletes.

Adaptation, Physiological↗

PubMed2005

On-the-Field Resistance-Tubing Exercises for Throwers: An Electromyographic Analysis.

Context: Athletes who throw commonly use rubber-tubing resistance exercises in the field setting to assist with warm-up before throwing. Yet no researchers have described which muscles are being activated or which exercises are most effective during rubber-tubing exercises used by throwers for warm-up.Objective: To describe the effectiveness of 12 rubber-tubing resistance exercises commonly used by throwers in activating the shoulder muscles important for throwing.Design: Descriptive research design.Setting: An applied biomechanics research laboratory.Patients or Other Participants: Fifteen physically active male subjects with no history of shoulder injury.Main Outcome Measure(s): Subjects randomly performed 12 rubber-tubing resistance exercises while we assessed muscle activation of the subscapularis, supraspinatus, teres minor, and rhomboid major by indwelling electromyography. Activation of the sternal portion of the pectoralis major, anterior deltoid, middle deltoid, latissimus dorsi, serratus anterior, biceps brachii, triceps brachii, lower trapezius, and infraspinatus muscles was assessed by surface electromyography.Results: Performance of 7 exercises (external rotation at 90 degrees of abduction, throwing deceleration, humeral flexion, humeral extension, low scapular rows, throwing acceleration, and scapular punch) resulted in the highest level of muscle activation of all muscles tested.Conclusions: These 7 exercises exhibited moderate activation (>20% maximal voluntary isometric contraction) in each muscle of the rotator cuff, the primary humeral movers, and the scapular stabilizer muscles. The results suggest that these exercises are most effective in activating the muscles important to the throwing motion and may be beneficial for throwers during their prethrowing warm-up routine.

Journal Article↗