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Purpose To determine differences in tibial tubercle–trochlear groove (TT-TG) distance between patients with a history of noncontact anterior cruciate ligament (ACL) injury and an uninjured control group. Methods MRI studies of 60 patients (age range, 14 to 25 years) with ACL-deficient (ACLD) knees were compared with 60 intact-ACL controls. All patients underwent MRI after a noncontact sports injury. TT-TG distances were measured on proton density–weighted axial images. Independent t -tests were used to determine differences in TT-TG distance between the ACLD and control groups. Results The mean TT-TG distance in the ACLD group was 12.07 mm (95% confidence interval [CI], 11.11 to 13.02), compared with 10.44 mm (95% CI, 9.64 to 11.24) in the control group. The mean TT-TG distance in the male ACLD group was 12.95 mm (95% CI, 11.39 to 14.51), compared with 10.87 mm (95% CI, 9.52 to 12.21) in the male control group. The mean TT-TG distance in the female ACLD group was 11.48 mm (95% CI, 10.24 to 12.71), compared with 10.04 mm (95% CI, 9.06 to 11.02) in the female control group. There were statistically significant differences in TT-TG distance between the ACLD and control groups ( P = .011) and between the male ACLD and control groups ( P = .041). Conclusions In adolescents and young adults, the TT-TG distance was statistically larger in knees with noncontact ACL tears than in intact-ACL control knees. When the groups were stratified on the basis of sex, only the male patients showed a statistical difference, with a 2.08 mm increase in TT-TG distance between the ACLD and intact-ACL patients. No difference in TT-TG distance was found between the ACLD and control groups for female patients. Despite the findings of this study, the clinical significance of an increased TT-TG distance as an isolated risk factor for noncontact ACL injury remains unanswered. Level of Evidence Level III, case-control study.

We are developing a series of systems science-based clinical tools that will assist in modeling, diagnosing, and quantifying postural control deficits in human subjects. In line with this goal, we have designed and constructed an experimental device and associated experimental task for identification of the human postural control system. In this work, we present a Quadratic Programming (QP) technique for optimizing a time-domain experimental input signal for this device. The goal of this optimization is to maximize the information present in the experiment, and therefore its ability to produce accurate estimates of several desired postural control parameters. To achieve this, we formulate the problem as a non-convex QP and attempt to maximize a measure (T-optimality condition) of the experiment's Fisher Information Matrix (FIM) under several constraints. These constraints include limits on the input amplitude, physiological output magnitude, subject control amplitude, and input signal autocorrelation. Because the autocorrelation constraint takes the form of a Quadratic Constraint (QC), we replace it with a conservative linear relaxation about a nominal point, which is iteratively updated during the course of optimization. We show that this iterative descent algorithm generates a convergent suboptimal solution that guarantees monotonic non-increasing of the cost function while satisfying all constraints during iterations. Finally, we present example experimental results using an optimized input sequence.

Cross-sectional laboratory study.To compare peak lower-limb, pelvis, and trunk kinematics and interjoint and intersegmental coordination in women with strong and weak hip muscle performance.Persons with lower extremity musculoskeletal disorders often demonstrate a combination of weak hip musculature and altered kinematics during weight-bearing dynamic tasks. However, the association between hip strength and kinematics independent of pathology or pain is unclear.Peak hip extensor and abductor torques were measured in 150 healthy young women. Of these, 10 fit the criteria for the strong group and 9 for the weak group, representing those with the strongest and weakest hip musculature, respectively, of the 150 screened individuals. Kinematics of the hip, knee, pelvis, and trunk were measured during the stance phases of walking and rate-controlled hopping. Hip/knee and pelvis/trunk coordination were calculated using the vector coding technique.There were no group differences in peak hip, knee, or pelvis kinematics. Participants in the weak group demonstrated greater trunk lateral bend toward the stance limb during hopping (P = .002, effect size [d] = 1.88). In the transverse plane, those in the weak group utilized less inphase coordination between the hip and the knee during walking (P = .036, d = 1.45) and more antiphase coordination between the hip and knee during hopping (P = .03, d = 1.47).In the absence of pain or pathology, poor hip muscle performance does not affect peak hip or knee joint kinematics in young women, but is associated with significantly different lower-limb and trunk/pelvis coordination during weight-bearing dynamic tasks. J Orthop Sports Phys Ther 2014;44(7):525-531. Epub 10 May 2014. doi:10.2519/jospt.2014.5028.

Objective: The purpose of the study was to examine changes in quality of life measures in patients who have undergone an intensive exercise program following a single level microdiskectomy. Design: Randomized controlled trial with blinded examiners. Setting: The study was conducted in outpatient physical therapy clinics. Subjects: Ninety-eight participants (53 male, 45 female) who had undergone a single-level lumbar microdiskectomy allocated to receive exercise and education or education only. Interventions: A 12-week periodized exercise program of lumbar extensor strength and endurance training, and mat and upright therapeutic exercises was administered. Outcome measures: Quality of life was tested with the Short Form 36 (SF-36). Measurements were taken 4–6 weeks postsurgery and following completion of the 12-week intervention program. Since some participants selected physical therapy apart from the study, analyses were performed for both an as-randomized (two-group) design and an as-treated (three-group) design. Results: In the two-group analyses, exercise and education resulted in a greater increase in SF-36 scales, role physical (17.8 vs. 12.1) and bodily pain (13.4 vs. 8.4), and the physical component summary (13.2 vs. 8.9). In the three-group analyses, post-hoc comparisons showed exercise and education resulted in a greater increase in the SF-36 scales, physical function (10.4 vs. 5.6) and bodily pain (13.7 vs. 8.2), and the physical component summary (13.7 vs. 8.9) when compared with usual physical therapy. Conclusions: An intensive, progressive exercise program combined with education increases quality of life in patients who have recently undergone lumbar microdiskectomy.

Intervertebral disc and facet joints are the two primary load-bearing structures of the lumbar spine, and altered loading to these structures may be associated with frontal plane spinal deviations.To determine the load on the lumbar facet joint and intervertebral disc under simulated frontal plane pelvic obliquity combined loading, an in vitro biomechanical study was conducted.An in vitro biomechanical study using a repeated-measures design was used to compare L4-L5 facet joint and intervertebral disc loading across pure moment and combined loading conditions.Eight fresh-frozen lumbosacral specimens were tested under five loading conditions: flexion/extension, lateral bending, axial rotation using pure moment bending (±10 Nm), and two additional tests investigating frontal plane pelvic obliquity and axial rotation (sacrum tilted left 5° and at 10° followed by a ±10-Nm rotation moment). Three-dimensional kinematics, facet load, and intradiscal pressures were recorded from the L4-L5 functional spinal unit.Sagittal and frontal plane loading resulted in significantly smaller facet joint forces compared with conditions implementing a rotation moment (p.05). The facet joint had the highest peak load during the 10° combined loading condition (124.0±30.2 N) and the lowest peak load in flexion (26.8±16.1 N). Intradiscal pressure was high in lateral flexion (495.6±280.9 kPa) and flexion (429.0±212.9 kPa), whereas intradiscal pressures measured in rotation (253.2±135.0 kPa) and 5° and 10° combined loading conditions were low (255.5±132.7 and 267.1±127.1 kPa, respectively).Facet loading increased during simulated pelvic obliquity in frontal and transverse planes, whereas intradiscal pressures were decreased compared with sagittal and frontal plane motions alone. Altered spinopelvic alignment may increase the loads experienced by spinal tissue, especially the facet joints.

Controlled laboratory study using a cross-sectional design.To characterize ankle and hip muscle performance in women with posterior tibial tendon dysfunction (PTTD) and compare them to matched controls. We hypothesized that ankle plantar flexor strength, and hip extensor and abductor strength and endurance, would be diminished in women with PTTD and this impairment would be on the side of dysfunction.Individuals with PTTD demonstrate impaired walking abilities. Walking gait is strongly dependent on the performance of calf and hip musculature.Thirty-four middle-aged women (17 with PTTD) participated. Ankle plantar flexor strength was assessed with the single-leg heel raise test. Hip muscle performance, including strength and endurance, were dynamometrically measured. Differences between groups and sides were assessed with a mixed-model analysis of variance.Females with PTTD performed significantly fewer single-leg heel raises and repeated sagittal and frontal plane non-weight-bearing leg lifts, and also had lower hip extensor and abductor torques than age-matched controls. There were no differences between sides for hip strength and endurance measures for either group, but differences between sides in ankle strength measures were noted in both groups.Women with PTTD demonstrated decreased ankle and hip muscle performance bilaterally.

Background Low back pain affects a substantial number of adults each year and is persistent or recurrent for many. Self-efficacy is an important predictor of functional recovery. Objective The purpose of this investigation was to assess the preliminary reliability and validity of the Low Back Activity Confidence Scale (LoBACS) for individuals with histories of low back pain or lumbar surgery. Design Two overlapping samples of patients who had undergone a microdiskectomy participated: a test-retest sample of 21 individuals and a validity sample of 53 individuals. Methods Low Back Activity Confidence Scale items pertaining to self-efficacy for functional activities (FnSE subscale), self-regulation of back health (Self-RegSE subscale), and regular exercise (ExSE subscale) were generated from existing literature and clinical observations. The test-retest sample completed the LoBACS twice, approximately 10 days apart. The validity sample completed the LoBACS and measures of functional performance, self-reported leisure and occupational physical activity, pain, fear beliefs, disability, and quality of life. Results The FnSE, Self-RegSE, and ExSE subscale scores and LoBACS total score had excellent to acceptable test-retest reliability (intraclass correlation coefficients of .924, .634, .710, and .850, respectively) and internal consistency (Cronbach α coefficients of .924, .804, .941, and .911, respectively). The LoBACS subscales were correlated in expected directions with physical performance, physical activity, pain, fear beliefs, disability, and quality of life, providing initial evidence of concurrent validity. Conclusions The findings provide preliminary content and concurrent validity and interrater and internal consistency reliability for the LoBACS measure of self-efficacy for individuals with histories of low back pain and lumbar microdiskectomy.

Study Design. In vitro evaluation of a chemical, injectable intervention for discectomy induced destabilization. Objective. To investigate the ability of two collagen crosslinking agents to restore mechanical properties to lumbar joints destabilized by surgical decompression procedures. Summary of Background Data. Posterior decompression surgery is a common procedure indicated for tissue pathology that interferes with surrounding neural structures. Previous in vitro, analytical, and clinical studies have shown that removal of load-supporting tissue can compromise joint stability mandating some form of postsurgical stabilization. Currently, no nonsurgical treatments are capable of restoring stability and preventing subsequent degeneration. Exogenous crosslinking of intact discs has shown a fourfold increase in joint stability. Methods. Fifteen bovine lumbar intervertebral joints were randomly separated into methylglyoxal or genipin treatment groups. Flexion-extension flexibility was quantified in three conditions: intact, postdecompression surgery, and after crosslinking reagent injections. Instability was quantified by calculating neutral zone (NZ), percentage of hysteresis, range of motion, and percentage of strain energy. Results. Simulated surgical decompression increased NZ 111% (P = 0.009), 28% (P = 0.004), range of motion 57% (P = 0.003), and decreased strain energy 37% (P = 0.004). For those discs undergoing methylglyoxal treatment NZ was subsequently reduced 68% (P = 0.012), hysteresis 28% (P = 0.018), range of motion 29% (P = 0.012), and strain energy was increased 71 % (P = 0.018). For discs subjected to genipin treatment, NZ was reduced 52% (P = 0.018), hysteresis 23% (P = 0.012), range of motion 44% (P = 0.017), and strain energy was increased 66% (P = 0.012). Mean NZ was lower than intact mean after both methylglyoxal and genipin treatments, 10% and 17% less, respectively, but these differences were not significant. Mean values for all other parameters posttreatment were within 6% of the corresponding intact mean values. Conclusion. Injections of crosslinking reagents into lumbar intervertebral discs after simulated decompression surgery restored joint stability according to all parameters. Similar results were found for genipin and methylglyoxal reagents. Implementing exogenous collagen crosslinking as an adjunct to current surgical decompression procedures may be beneficial in preventing or delaying subsequent spinal instability and degeneration.

Deficiencies The lumbar facet joints are the major load bearing elements in the lumbar spine posterior column and they are considered one of the anatomical structures that can cause low back pain. They also contribute to the amount and type of lumbar spine motion.Copyright © 2010 by ASME

BackgroundRestoration of physical function following lumbar microdiskectomy may be influenced by the postoperative care provided.ObjectiveThe purpose of this study was to examine the effectiveness of a new interventional protocol to improve functional performance in patients who have undergone a single-level lumbar microdiskectomy.SettingThe study was conducted in physical therapy outpatient clinics.Design and ParticipantsNinety-eight participants (53 male, 45 female) who had undergone a single-level lumbar microdiskectomy were randomly allocated to receive education only or exercise and education.Intervention and MeasurementsThe exercise intervention consisted of a 12-week periodized program of back extensor strength (force-generating capacity) and endurance training and mat and upright therapeutic exercises. The Oswestry Disability Index (ODI) and physical measures of functional performance were tested 4 to 6 weeks postsurgery and 12 weeks later, following completion of the intervention program. Because some participants sought physical therapy outside of the study, postintervention scores were analyzed for both an as-randomized (2-group) design and an as-treated (3-group) design.ResultsIn the 2-group analyses, exercise and education resulted in a greater reduction in ODI scores and a greater improvement in distance walked. In the 3-group analyses, post hoc comparisons showed a significantly greater reduction in ODI scores following exercise and education compared with the education-only and usual physical therapy groups.LimitationsThe limitations of this study include a lack of adherence to group assignment, disproportionate therapist contact time among treatment groups, and multiple use of univariate analyses.ConclusionsAn intensive, progressive exercise program combined with education reduces disability and improves function in patients who have undergone a single-level lumbar microdiskectomy.

Navicular drop (ND) measurement may be a valuable examination technique for patients with rheumatoid arthritis (RA). However, no data exist on reliability for this technique in patients with RA. The purposes of this study were: (1) to determine interrater and intrarater reliability of ND measurements in people with RA, (2) to compare ND values of people with RA with published normative data, and (3) to investigate ND measurement error associated with the use of skin markings.Ten women (20 feet) with RA consented to participate.Patients completed demographic and function questionnaires. Navicular height (NH) measurements were taken by 2 physical therapists and 1 physical therapist student, following four 1-hour training sessions, using standardized methods and a digital height gauge. Four different NH measurements were taken 3 times on each foot by each of the 3 examiners during a morning session and then repeated during an afternoon session on the same day. Navicular drop values were calculated, including ND1 (as reported in the literature), ND2 (compensating for skin error), and ND3 (single-limb stance). Intraclass correlation coefficients (ICCs) and standard errors of measurement (SEMs) were used to establish reliability.Means (+/-SD) for each ND measure for sessions 1 and 2, respectively, were as follows: ND1=8.36+/-5.29 mm and 8.29+/-5.24 mm, ND2=9.95+/-5.44 mm and 9.57+/-5.37 mm. The ICCs (2,1 and 2,k, respectively) for all interrater measurements ranged from .67 to .92 (SEM=2.0-3.3 mm) and from .85 to .97 (SEM=1.1-2.0 mm). The ICCs (2,1 and 2,k, respectively) for intrarater measurements ranged from .73 to .95 (SEM=1.3-2.8 mm) and from .90 to .98 (SEM=0.7-1.6 mm). Paired t tests showed the means of ND1 and ND2 for each examiner and for both sessions were significantly different.The results suggest that ND measurements for people with RA can be taken reliably by clinicians with varied experience. The ND values for our subjects were slightly greater than reported normal values of 6 to 8 mm. Error associated with skin markings was statistically significant for all sessions and examiners.

Powerful new LEDs provide enough luminosity for a single one to illuminate a transparent EXIT sign, but efficient injection means are required, with luminance-uniformity a prime goal. We present a totally-internally-reflecting `Black Hole' indentation on the waveguide surface. This cuspated configuration deflects the light from an immersed LED, aimed perpendicular to the plane of the waveguide, into guided light trapped within the slab, to be extracted by the sign's alphabetic features. In spherical coordinates, a +/- 60 degree(s) output cone (for example) is deflected into the 360 degree(s)-azimuth guided range of +/- 47 degree(s). That is, this reflector transforms a polar cone into an equatorial swath, a symmetry that is useful whenever the total horizon must be dealt with, just as a lighthouse, or better yet a marker buoy, must send warning light to all the quarters of the compass. In its circularly symmetric configurations, this device offers a removable disc, optically bonded to the LED source, that completely hides the source from view above the indentation. Non-waveguide, stand-alone illumination applications include aircraft-warning beacons, alarm flashers, and near-field illuminators.

Background Low back pain remains a costly quality-of-life-related health problem. Microdiscectomy is often the surgical procedure of choice for a symptomatic, single-level, lumbar disc herniation in younger and middle-aged adults. The question of whether a post-microdiscectomy exercise program enhances function, quality of life, and disability status has not been systematically explored. Thus, the overall purpose of this study is to assess immediate and long-term outcomes of an exercise program, developed at University of Southern California (USC), targeting the trunk and lower extremities (USC Spine Exercise Program) for persons who have undergone a single-level microdiscectomy for the first time. Methods/design One hundred individuals between the ages of 18 and 60 who consent to undergo lumbar microdiscectomy will be recruited to participate in this study. Subjects will be randomly assigned to one of two groups: 1) one session of back care education, or 2) a back care education session followed by the 12-week USC Spine Exercise Program. The outcome examiners (evaluators), as well as the data managers, will be blinded to group allocation. Education will consist of a one-hour "one-on-one" session with the intervention therapist, guided by an educational booklet specifically designed for post-microdiscectomy care. This session will occur four to six weeks after surgery. The USC Spine Exercise Program consists of two parts: back extensor strength and endurance, and mat and upright therapeutic exercises. This exercise program is goal-oriented, performance-based, and periodized. It will begin two to three days after the education session, and will occur three times a week for 12 weeks. Primary outcome measures include the Oswestry Disability Questionnaire, Roland-Morris Disability Questionnaire, SF-36® quality of life assessment, Subjective Quality of Life Scale, 50-foot Walk, Repeated Sit-to-Stand, and a modified Sorensen test. The outcome measures in the study will be assessed before and after the 12-week post-surgical intervention program. Long-term follow up assessments will occur every six months beginning one year after surgery and ending five years after surgery. Immediate and long-term effects will be assessed using repeated measures multivariate analysis of variance (MANOVA). If significant interactions are found, one-way ANOVAs will be performed followed by post-hoc testing to determine statistically significant pairwise comparisons. Discussion We have presented the rationale and design for a randomized controlled trial evaluating the effectiveness of a treatment regimen for people who have undergone a single-level lumbar microdiscectomy.