ABSTRACT
BACKGROUND: Isokinetic eccentric training of the wrist extensors has recently been shown to be effective in treating chronic lateral epicondylosis. However, isokinetic dynamometry is not widely available or practical for daily exercise prescription. Therefore, the objective of this study was to assess the efficacy of a novel eccentric wrist extensor exercise added to standard treatment for chronic lateral epicondylosis. MATERIALS AND METHODS: Twenty-one patients with chronic unilateral lateral epicondylosis were randomized into an eccentric training group (n = 11, 6 men, 5 women; age 47 +/- 2 yr) and a Standard Treatment Group (n = 10, 4 men, 6 women; age 51 +/- 4 yr). DASH questionnaire, VAS, tenderness measurement, and wrist and middle finger extension were recorded at baseline and after the treatment period. RESULTS: Groups did not differ in terms of duration of symptoms (Eccentric 6 +/- 2 mo vs Standard 8 +/- 3 mos., P = .7), number of physical therapy visits (9 +/- 2 vs 10 +/- 2, P = .81) or duration of treatment (7.2 +/- 0.8 wk vs 7.0 +/- 0.6 wk, P = .69). Improvements in all dependent variables were greater for the Eccentric Group versus the Standard Treatment Group (percent improvement reported): DASH 76% vs 13%, P = .01; VAS 81% vs 22%, P = .002, tenderness 71% vs 5%, P = .003; strength (wrist and middle finger extension combined) 79% vs 15%, P = .011. DISCUSSION: All outcome measures for chronic lateral epicondylosis were markedly improved with the addition of an eccentric wrist extensor exercise to standard physical therapy. This novel exercise, using an inexpensive rubber bar, provides a practical means of adding isolated eccentric training to the treatment of chronic lateral epicondylosis.
Subject(s)
Exercise Therapy/methods , Muscle Contraction/physiology , Muscle, Skeletal/physiopathology , Tennis Elbow/therapy , Wrist/physiology , Chronic Disease , Female , Follow-Up Studies , Humans , Male , Middle Aged , Prospective Studies , Range of Motion, Articular , Tennis Elbow/physiopathology , Treatment OutcomeABSTRACT
A constituent based nonlinear viscoelastic (VE) model was modified from a previous study (Vena, et al., 2006, "A Constituent-Based Model for the Nonlinear Viscoelastic Behavior of Ligaments," J. Biomech. Eng., 128, pp. 449-457) to incorporate a glycosaminoglycan (GAG)-collagen (COL) stress balance using compressible elastic stress constitutive equations specific to articular cartilage (AC). For uniaxial loading of a mixture of quasilinear VE constituents, time constant and relaxation ratio equations are derived to highlight how a mixture of constituents with distinct quasilinear VE properties is one mechanism that produces a nonlinear VE tissue. Uniaxial tension experiments were performed with newborn bovine AC specimens before and after approximately 55% and approximately 85% GAG depletion treatment with guanidine. Experimental tissue VE parameters were calculated directly from stress relaxation data, while intrinsic COL VE parameters were calculated by curve fitting the data with the nonlinear VE model with intrinsic GAG viscoelasticity neglected. Select tissue and intrinsic COL VE parameters were significantly different from control and experimental groups and correlated with GAG content, suggesting that GAG-COL interactions exist to modulate tissue and COL mechanical properties. Comparison of the results from this and other studies that subjected more mature AC tissue to GAG depletion treatment suggests that the GAGs interact with the COL network in a manner that may be beneficial for rapid volumetric expansion during developmental growth while protecting cells from excessive matrix strains. Furthermore, the underlying GAG-COL interactions appear to diminish as the tissue matures, indicating a distinctive remodeling response during developmental growth.
Subject(s)
Cartilage, Articular/physiology , Collagen/physiology , Glycosaminoglycans/metabolism , Models, Biological , Animals , Animals, Newborn , Cattle , Compressive Strength , Elasticity , Guanidine/pharmacology , Mathematics , Nonlinear Dynamics , Time Factors , ViscosityABSTRACT
CONTEXT: Scapular strengthening is thought to be an important component of the rehabilitation of patients with internal impingement. OBJECTIVE: To determine the effect of scapular-retractor-muscle fatigue on internal- and external-rotation-torque production in patients with internal impingement. DESIGN: Case control study. SETTING: Outpatient clinic. PARTICIPANTS: 15 patients and 18 healthy subjects. INTERVENTION: A scapular-retractor-fatigue protocol. MAIN OUTCOME MEASURE: Shoulder-rotation-torque production. RESULTS: After the scapular-retractor-fatigue protocol external-rotation strength was reduced in patients (involved 25%, noninvolved 19%; P < .001). CONCLUSION: Fatigue in the scapular retractors resulted in lower shoulder-rotation-torque production. These findings emphasize the importance of the scapular retractors for proper function of the shoulder rotators with the arm in an abducted position in patients with internal impingement.
