STUDY DESIGN: A descriptive and exploratory investigation of lumbar extensor performance in persons with a recent history of single-level microdiscectomy. OBJECTIVE: To provide a justification for and outline the procedure of assessing lumbar extensor musculature performance. BACKGROUND: The time of holding an unsupported trunk horizontally, also called the Sorensen Test (ST), is often used to test the lumbar extensor endurance of healthy and patient populations, but may need to be modified for some patients. METHODS AND MEASURES: Sixty-eight participants completed a modified ST procedure, along with several questionnaires and performance measures, approximately 4 to 6 weeks after a single-level microdiscectomy. Participants were classified as either able to complete or unable to complete the final position of the modified ST procedure (trunk horizontal). RESULTS: Fifty-one point five percent of the participants could not attain the final position of the modified ST procedure due to either pain or perceived exertion. Those who could not attain the final position of the modified ST procedure had significantly lower scores (compared to those who could) on most measures. A majority (78.8%) of the participants in this study who were unable to complete the ST were correctly classified using the Fear-Avoidance Belief Questionnaire Work Subscale and a 24-hour activity questionnaire. CONCLUSION: The ability to attain the final position of the modified ST procedure was closely associated with fear-avoidance beliefs and physical activity level, suggesting that this test may be too intense (either real or perceived) for many patients within 4 to 6 weeks following a single-level microdiscectomy.

J Orthop Sports Phys Ther. 2007;37(7):356-363; published online 29 May 2007. doi:10.2519/jospt.2007.2366

KEY WORDS: Fear-Avoidance Belief Questionnaire, lumbar musculoskeletal performance, Sorensen test

STUDY DESIGN: A single-group descriptive experimental design. OBJECTIVES: To determine the fascicle length change in the tibialis anterior (TA) and the vastus lateralis (VL) muscles during walking. BACKGROUND: The length of the muscle fibers during isometric actions and during dynamic functional activities is affected by the compliance of the tendon and aponeurosis. The TA and VL muscles have important functions both in stance and swing phases of gait. Therefore, it is important to understand the dynamics of the muscle length change as it relates to the type of muscle actions in walking. METHODS AND MEASURES: Nine healthy subjects performed treadmill walking while fascicle length, muscle activity (electromyographic signal), and joint angle (knee and ankle) were recorded. Fascicle length was measured using real-time ultrasound imaging. Fascicle length and joint angle during the gait cycle were analyzed using a repeated-measures analysis of variance. RESULTS: During the initial portion of stance when the TA and VL muscles were active, the ankle plantar flexed and the knee joint flexed, suggesting muscle-tendon complex lengthening, but the fascicle length of both muscles remains constant (TA: P=.93; VL: P=.22). The TA muscle was again active during the initial portion of swing phase while the ankle dorsiflexed, and the fascicle length decreased (P<.05).  The VL muscle became active again at the end of swing as the knee extended, and the fascicle length decreased (P<.05). CONCLUSIONS: The lack of change in fascicle length during the initial portions of stance phase suggests a nearly isometric muscle action of the TA and VL. There is a possible interaction occurring between the fascicle and tendon in the TA and VL such that the tendon lengthens to allow joint motion and potentially to store elastic energy.

J Orthop Sports Phys Ther. 2007;37(7):372-379, published online 16 April 2007. doi:10.2519/jospt.2007.2440

KEY WORDS: muscle architecture, tendon compliance, ultrasound

STUDY DESIGN: Descriptive, cohort design. OBJECTIVES: To comprehensively examine sex differences in clinical measures of static lower extremity alignment (LEA). BACKGROUND: Sex differences in LEA have been included among a myriad of risk factors as a potential cause for the increased prevalence of knee injury in females.  While clinical observations suggest sex differences in LEA exist, little empirical data are available to support these sex differences or the normal values that should be expected in a healthy population. METHODS AND MEASURES: The right and left static LEA of 100 healthy college-age participants (50 males [mean ± SD age, 23.3 ± 3.6 years; height, 177.8 ± 8.0 cm; body mass, 80.4 ± 11.6 kg] and 50 females [mean ± SD age, 21.8 ± 2.5 years; height, 164.3 ± 6.9 cm body mass, 67.4 ± 15.2 kg]) were measured. Each alignment characteristic was analyzed via separate repeated-measures analyses of variance, with 1 between-subject factor (sex) and 1 within-subject factor (side). RESULTS: There were no significant sex-by-side interactions and no differences by side. Females had greater mean anterior pelvic tilt, hip anteversion, quadriceps angles, tibiofemoral angles, and genu recurvatum than males (P<.0001). No sex differences were observed in tibial torsion (P = .131), navicular drop (P = .130), or rearfoot angle (P = .590). CONCLUSION: Sex differences in LEA indicate that females, on average, have greater anterior pelvic tilt, thigh internal rotation, knee valgus, and genu recurvatum. These sex differences were not accompanied by differences in the lower leg, ankle, and foot. Understanding these collective sex differences in LEA may help us to better examine the influence of LEA on dynamic knee function and clarify their role as a potential injury risk factor.

J Orthop Sports Phys Ther. 2007;37(7):389-398, published online 16 April 2007. doi:10.2519/jospt.2007.2487

KEY WORDS: malalignment, posture, risk factor assessment

STUDY DESIGN: Case series. CASE DESCRIPTION: Four patients who had developed knee extension motion loss following anterior cruciate ligament reconstruction were referred to physical therapy for treatment. They were treated with drop-out casting and completed a Lower Extremity Functional Scale at baseline, at the time of application of the drop-out casting, and at discharge. OUTCOMES: Three males and 1 female with a mean age of 20.5 years (range, 18-22 years) were referred to physical therapy a mean of 31 days (range, 19-49 days) following bone-patella tendon-bone autograft anterior cruciate ligament reconstruction. The mean number of physical therapy sessions attended was 29.5 visits (range, 20-47 visits). The mean improvement in knee extension range of motion (ROM) and knee flexion ROM prior to the application of drop-out casting was 4.3^o (range, -1^o to 10^o) and 24.3^o (range, 0^o to 40^o), respectively. The mean improvement on the Lower Extremity Functional Scale was 10.3 points prior to drop-out casting. At time of discharge, the total mean improvement in knee extension ROM loss was 11.0^o (range, 4^o to 15^o), knee flexion ROM was 30.8^o (range, 22^o to 35^o), and Lower Extremity Functional Scale was 12 points (range, -5 to 21 points). Two of the patients were able to complete a running program without difficulty, while the other 2 patients had difficulty with higher-level activities. DISCUSSION: Despite the low incidence of knee extension ROM loss following surgery, the inability to achieve full knee extension does occur and can have debilitating consequences. When early emphasis of full passive knee extension has been inadequate, these results suggest that improving knee extension motion without inhibiting knee flexion motion is possible with the use of a drop-out cast. Future research should focus on comparison of drop-out casting to dynamic splinting, as well as the optimal frequency and duration of low-load long-duration stretching using a drop-out cast.

J Orthop Sports Phys Ther. 2007;37(7):404-411, published online 29 May 2007. doi:10.2519/jospt.2007.2466

KEY WORDS:  arthrofibrosis, knee extension lag, splinting, stiff knee