STUDY DESIGN: Randomized controlled trial with repeated measures. OBJECTIVES: To determine the effect of trunk stability training on vertical takeoff velocity. BACKGROUND: Trunk stability training is commonly used in sports training programs; however, the effects of stability training on performance enhancement are not known. Trunk stability training may provide a more stable pelvis and spine from which the leg muscles can generate action, may better link the upper body to the lower body, or may enhance leg muscle activation, thus promoting optimal force production during sporting activities such as a vertical jump. METHODS AND MEASURES: Fifty-five athletes were randomly assigned to 1 of 4 training groups: trunk stability (TS), leg strength (LS), trunk stability and leg strength (TL), and control (CO). Subjects were tested 3 times: at pretraining, after 3 weeks of training, and after 9 weeks of training. A repeated-measures analysis of covariance (ANCOVA) was used to examine differences among groups for vertical takeoff velocity measured indirectly using a force plate. Pretraining takeoff velocity and body mass were used as covariates. RESULTS: After 3 and 9 weeks, the training groups were not different from each other. After 9 weeks of training, all 3 training groups had a greater takeoff velocity than the control group (P‹.05). After 3 weeks of training, only the TS group had a greater takeoff velocity than the control group (P‹.05). Only the TL group increased significantly in vertical takeoff velocity between the third- and ninth-week testing periods (P‹.05). CONCLUSIONS: Nine weeks of trunk stability training was similarly effective in enhancing vertical takeoff velocity as leg strength training or the combination of trunk stability and leg strength training.

J Orthop Sports Phys Ther. 2007;37(5):223-231; published online 15 March 2007. doi:10.2519/jospt.2007.2331

KEY WORDS: athletic performance, core stability, neural control, vertical jump

STUDY DESIGN: A case-control study, with single observation. OBJECTIVES: To compare the onset timing and activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) between subjects with and without patellofemoral pain syndrome (PFPS) at various step heights. BACKGROUND: It has been theorized that delayed or reduced VMO activity relative to the VL contributes to lateral patellar tracking and PFPS. However, conflicting evidence exists in the literature regarding this proposed mechanism. The lack of agreement among studies may be attributed to inconsistent knee flexion angles used in previous studies. METHODS AND MEASURES: Twenty subjects with PFPS (mean ± SD age, 29.5 ± 10 yrs) and 20 control subjeccts (mean ± SD age, 25.4 ± 3.1 yrs) ascended 5 different step heights, while knee kinematics and quadriceps EMG data were collected. Knee flexion angle at foot-step contact, VMO-VL onset timing, and VMO/VL activation ratios were analyzed between groups and step heights using 2-factor analyses of variance (ANOVAs) with repeated measures (α = .05). RESULTS: Individuals with PFPS demonstrated 4.7° (P = .038) more knee flexion at foot-step contact than control subjects. Despite greater knee flexion with increased step height (P‹.001), no differences in onset timing or activation magnitude ratio were present between groups or across step heights. However, individuals with PFPS displayed a significantly increased activation duration ratio compared to the control group (P = .043). CONCLUSION: Quadriceps onset timing and activation magnitude during stair ascent was similar between individuals with and without PFPS, regardless of step height. Thus, the results of this study are in agreement with evidence indicating no difference in VMO-VL timing and VMO/VL activation magnitude ratio between individuals with and without PFPS.

J Orthop Sports Phys Ther. 2007;37(5):239-244; published online 15 March 2007. doi:10.2519/jospt.2007.2421

KEY WORDS: activation ratio, anterior knee pain, EMG, onset delay, stair climbing

The purpose of this manuscript is to provide current information regarding the examination, conservative treatment, and surgical treatment for individuals with posttraumatic arthritis. Although inflammatory and osteoarthritis can occur, post­traumatic arthritis is the most common form of arthritis to affect the ankle. Posttraumatic ankle arthritis occurs in a generally younger, active population. It is characterized radiographically by an asymmetrical degenerative process and may be associated with a history of trauma, instability, and/or lower extremity malalignment.

When choos­ing between conservative/nonoperative versus surgical intervention, the extent of subchondral bone exposed and the time over which the arthritis has developed are factors that should be consid­ered. The role and effectiveness of conservative treatment, such as medication, patient education, shoe modification, bracing, stretching, mobiliza­tion, strengthening, and symptom management, need to be further determined. Surgical proce­dures for posttraumatic ankle arthritis can include distraction arthroplasty, arthrodesis, or total ankle arthroplasty.

Unlike the relatively new procedure of distraction arthroplasty, the outcomes for arthrod­esis have been well defined. Arthrodesis generally has a good outcome, but its limitations have been recognized. These limitations include the extended time required to achieve fusion, potential for non­union, arthritis developing in adjacent joints, leg length discrepancy, malalignment, chronic edema, symptoms due to the hardware, stress fractures, and continued pain. While first generation total an­kle arthroplasty led to poor results, advancements in prosthetic design and surgical technique have revived optimism regarding total ankle arthroplasty as an alternative to arthrodesis. The key for the fu­ture of total ankle arthroplasty may not be related to the development of newer ankle components but rather in refining the criteria to determine who would best benefit from joint replacement versus fusion.

J Orthop Sports Phys Ther. 2007;37(5):253-259. doi:10.2519/jospt.2007.2404

KEY WORDS: arthrodesis, arthroplasty, joint fusion, joint replacement

STUDY DESIGN: A controlled, randomized prospective study. OBJECTIVE: To assess the changes in paratendon microcirculation after 12 weeks of daily painful eccentric training in individuals with chronic Achilles tendinopathy. BACKGROUND: Changes in tendon and paratendon microcirculation are evident in insertional and midportion Achilles tendinopathy. Whether the paratendon is involved in eccentric training response is not known. METHODS: Twenty patients with chronic Achilles tendinopathy were recruited for a prospective, controlled trial using eccentric exercise. A laser Doppler system assessed capillar blood flow (flow), tissue oxygen saturation (SO₂), and postcapillary venous filling pressure (rHB) at 8 paratendon locations at depths of 2 and 8mm. RESULTS: Pain in the eccentric-training group was reduced by 48% (from a mean of 4.1 ± 2.9 to 2.1 ± 2.2, P‹.05). Deep paratendon blood flow decreased at the midportion paratendon location (P‹.05). Superficial blood flow at the medial distal midportion position (by 31%, P = .008) and the lateral proximal midportion location (by 45%, P = .016) were significantly decreased postintervention. No significant change of superficial or deep paratendon oxygenation was found after intervention as compared to baseline. Deep paratendon postcapillary venous filling pressures were significantly reduced following eccentric training (P‹.05). CONCLUSION: An eccentric-training program performed daily over 12 weeks reduced the increased paratendinous capillary blood flow in Achilles tendinopathy by as much as 45% and decreased pain level on a visual analog scale. Local paratendon oxygenation was preserved while paratendinous postcapillary venous filling pressures were reduced after 12 weeks of eccentric training, which appears to be beneficial from the perspective of microcirculation.

J Orthop Sports Phys Ther. 2007;37(5):269-276; published online 15 March 2007. doi:10.2519/jospt.2007.2296

KEY WORDS: tendon, microcirculation, training, rehabilitation, ultrasound