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PubMed2004

Cane-assisted gait biomechanics and electromyography after total hip arthroplasty.

OBJECTIVE: To quantify the effects of cane use during walking on hip joint kinematics, kinetics, and muscle activity patterns after unilateral total hip arthroplasty (THA). DESIGN: Nonrandomized experimental design. SETTING: Urban inpatient hospital. PARTICIPANTS: Adults (n=9 men, 2 women) with no history of orthopedic or neuromuscular disease who underwent elective unilateral THA. INTERVENTION: Gait was assessed preoperatively and 4 and 8 months postoperatively. MAIN OUTCOME MEASURES: Three-dimensional hip joint motion and moments and electromyographic patterns of gluteus medius, tensor fascia latae, lateral hamstring, and vastus lateralis were measured during level walking, with and without use of a straight cane. RESULTS: When a cane was held in the contralateral hand, the abduction moment of the affected hip decreased by 26%, whereas that of the contralateral hip increased by 28%. Use of a cane in THA rehabilitation is important because it reduces the load on the operative hip so that bone and soft tissues can heal. Our results suggest that load reduction was successful on the operative side, but the loads on the contralateral side were increased. CONCLUSIONS: After unilateral arthroplasty, subjects using a cane had increased hip abduction moments on the nonoperative hip and decreased hip abduction moments on the operative hip. Clinicians should be mindful of the effects of cane use on the contralateral hip.

Arthroplasty, Replacement, Hip↗

PubMed1997

Equinus deformity in cerebral palsy: recurrence after tendo Achillis lengthening.

Twenty-seven patients with cerebral palsy (CP) were recalled and studied in detail 2 to 9 years post tendo Achillis lengthening (TAL). The recurrence rate of equinus deformity was 22.2%. Multiple clinical characteristics and follow-up examination findings were analyzed to determine their relation to recurrence. The recurrence group had a significantly (P<0.05) smaller preoperative popliteal angle, a greater popliteal angle at follow-up, and a greater change in popliteal angle from preoperative to follow-up than the non-recurrence group. This indicated that increasing hamstring contracture was the major factor influencing recurrence. Spasticity of tibialis posterior and leg-length discrepancy may be related factors as well.

Achilles Tendon↗

PubMed1990

Isolated avulsion of the biceps femoris insertion. A case report.

The clinical, roentgenographic, and operative findings of an isolated biceps femoris avulsion in a 21-year-old man demonstrated the significance of the static stabilizers about the knee, menisci, and articular cartilage. Examination of the dynamic structures about the knee, however, may present a diagnostic problem. A systematic examination of the musculature (hamstrings, quadriceps, and patellofemoral mechanism) should be included in the evaluation of every acute knee injury. Special attention should be given to the surface anatomy as well as function of the knee.

Adult↗

PubMed1992

A clinical exercise system for paraplegics using functional electrical stimulation.

A low cost clinical exercise system was developed for the spinal cord injured, based on a bicycle ergometer and electrical stimulation. A pilot project was conducted, using the system, to examine the effects of stimulation induced cycling in long term paraplegics. The project comprised 2 phases of exercise, a strengthening phase involving a 12 week programme of electrical stimulation to the quadriceps and hamstrings and a 12 week cycling phase. Physiological, morphological and biochemical parameters were measured for each subject, at the beginning of the programme and following each phase. Results showed that a programme of stimulation induced lower limb exercise increased the exercise tolerance of all patients, as determined by a progressive increase in exercise time, cycling rate and exercise load. The enhanced exercise tolerance was a result of increases in local muscle strength and endurance. Increases in thigh muscle area and joint range of motion were recorded and all incomplete subjects reported an improvement in functional capabilities and general wellbeing.

Adult↗

PubMed2005

Acute effects of passive muscle stretching on sprint performance.

The results of previous research have shown that passive muscle stretching can diminish the peak force output of subsequent maximal isometric, concentric and stretch-shortening contractions. The aim of this study was to establish whether the deleterious effects of passive stretching seen in laboratory settings would be manifest in a performance setting. Sixteen members (11 males, 5 females) of a Division I NCAA track athletics team performed electronically timed 20 m sprints with and without prior stretching of the legs. The experiment was done as part of each athlete's Monday work-out programme. Four different stretch protocols were used, with each protocol completed on a different day. Hence, the test period lasted 4 weeks. The four stretching protocols were no-stretch of either leg (NS), both legs stretched (BS), forward leg in the starting position stretched (FS) and rear leg in the starting position stretched (RS). Three stretching exercises (hamstring stretch, quadriceps stretch, calf stretch) were used for the BS, FS and RS protocols. Each stretching exercise was performed four times, and each time the stretch was maintained for 30 s. The BS, FS and RS protocols induced a significant (P < 0.05) increase (approximately 0.04 s) in the 20 m time. Thus, it appears that pre-event stretching might negatively impact the performance of high-power short-term exercise.

Adult↗

PubMed2006

[Strength, postural and gait changes following rehabilitation in multiple sclerosis: a preliminary study].

OBJECTIVE: To evaluate the impact of rehabilitation on balance, gait and strength in inpatients with multiple sclerosis (MS). METHODS: Twenty-one in patients with MS benefited from a program of rehabilitation with evaluation before and after rehabilitation. Balance was assessed by stabilometry, walking speed with use of a locometer device and maximal peak torque of knee extensor and flexor with use of an isokinetic dynamometer at 60 degrees /s speed. The functional independence measure (FIM) was also applied before and after rehabilitation. RESULTS: After rehabilitation, patients showed significant improvement in balance with opened and closed eyes, velocity gait, strength of the lower quadriceps and the higher hamstrings and FIM values. Absolute values of gait speed and strength parameters were related as were improvement in velocity speed and the higher hamstrings. CONCLUSION: The results are encouraging and confirm the interest and tolerance of a program of rehabilitation among patients with MS.

Adult↗

PubMed2001

Flexibility and passive resistance of the hamstrings of young adults using two different static stretching protocols.

This investigation determined the effects of a static stretching program with different stretching protocols on the flexibility and passive resistance of the hamstrings of young adults. Forty healthy subjects (24 males and 16 females) aged 18 to 30 years were randomly assigned to one of four groups. The two training groups underwent static stretch training of the hamstrings either with a four-week protocol or with an eight-week protocol. The other two groups acted as control groups. A significant increase in flexibility of hamstrings was found in both of the two training groups (P<0.05). No difference was found in the range of motion gained between the two training groups. An increase in passive resistance at the corresponding maximal joint angle was only demonstrated in the four-week training group (P<0.05). Both protocols are effective in terms of improving flexibility of hamstrings. However, if injury is reduced when there is relatively lower passive resistance at the end-of-range, then the eight-week training regimen would be recommended.

Adolescent↗

PubMed2002

Gender differences in strength and lower extremity kinematics during landing.

This study evaluated kinematic, vertical ground reaction forces, and strength variables in healthy collegiate female basketball, volleyball, and soccer players compared with matched male subjects. Thirty athletes did single-leg landing and forward hop tasks. An electromagnetic tracking device synchronized with a force plate provided kinematic data and vertical ground reaction force data, respectively. Maximum angular displacement and time to maximum angular displacement kinematic variables were calculated for hip flexion, abduction, rotation, knee flexion, and lower leg rotation. Vertical ground reaction force data normalized to body mass provided impulse, maximum force, time to maximum force, and stabilization time variables. An isokinetic device measured quadriceps and hamstring peak torque to body mass at 60 degrees /second. With both tasks, females had significantly less knee flexion and lower leg internal rotation maximum angular displacement, and less knee flexion time to maximum angular displacement than males. For the single-leg land, females had significantly more hip internal rotation maximum angular displacement, and less lower leg internal rotation time to maximum angular displacement than males. For the forward hop, females had significantly more hip rotation time to maximum angular displacement than males. Females also had significantly less peak torque to body mass for the quadriceps and hamstrings than males. Weaker thigh musculature may be related to the abrupt stiffening of the knee and lower leg on landing in females.

Adult↗

PubMed2000

Access to pedestrian roads, daily activities, and physical performance of adolescents.

STUDY DESIGN: A cross-sectional study using a questionnaire and physical tests was performed. OBJECTIVE: To study how access to pedestrian roads and daily activities are related to low back strength, low back mobility, and hip mobility in adolescents. SUMMARY OF BACKGROUND DATA: Although many authorities express concern about the passive lifestyle of adolescents, little is known about associations between daily activities and physical performance. METHODS: This study compared 38 youths in a community lacking access to pedestrian roads with 50 youths in nearby area providing excellent access to pedestrian roads. A standardized questionnaire was used to obtain data about pedestrian roads, school journeys, and activities from the local authorities and the pupils. Low back strength was tested as static endurance strength, low back mobility by modified Schober techniques, and hip mobility by goniometer. For statistical analyses, a P value of 0.05 or less determined significance. RESULTS: In the area using school buses, the pupils had less low back extension, less hamstring flexibility, and less hip abduction, flexion, and extension than pupils in the area with pedestrian roads. Multivariate analyses showed no associations between walking or bicycling to school and anatomic function, but regular walking or bicycling to leisure-time activities associated positively with low back strength, low back extension, hip flexion, and extension. Distance by school bus associated negatively with hip abduction, hip flexion, hip extension, and hamstring flexibility (P<0.001). Time spent on television or computer associated negatively but insignificantly with low back strength, hamstring flexibility, hip abduction, and flexion (P<0.1). CONCLUSION: The results indicate that access to pedestrian roads and other lifestyle factors are associated with physical performance.

Adolescent↗

PubMed2006

Type of acute hamstring strain affects flexibility, strength, and time to return to pre-injury level.

OBJECTIVES: To investigate possible links between aetiology of acute, first time hamstring strains in sprinters and dancers and recovery of flexibility, strength, and function as well as time to return to pre-injury level. [figure: see text]. METHODS: Eighteen elite sprinters and 15 professional dancers with a clinically diagnosed hamstring strain were included. They were clinically examined and tested two, 10, 21, and 42 days after the acute injury. Range of motion in hip flexion and isometric strength in knee flexion were measured. Self estimated and actual time to return to pre-injury level were recorded. Hamstring reinjuries were recorded during a two year follow up period. RESULTS: All the sprinters sustained their injuries during high speed sprinting, whereas all the dancers were injured while performing slow stretching type exercises. The initial loss of flexibility and strength was greater in sprinters than in dancers (p<0.05). At 42 days after injury, both groups could perform more than 90% of the test values of the uninjured leg. However, the actual times to return to pre-injury level of performance were significantly longer (median 16 weeks (range 6-50) for the sprinters and 50 weeks (range 30-76) for the dancers). Three reinjuries were noted, all in sprinters. CONCLUSION: There appears to be a link between the aetiologies of the two types of acute hamstring strain in sprinters and dancers and the time to return to pre-injury level. Initially, sprinters have more severe functional deficits but recover more quickly.

Adolescent↗

PubMed2001

The effect of hand-grip stabilization on isokinetic torque at the knee.

Isokinetic dynamometers commonly measure muscle strength during conditioning and rehabilitation. Previous studies have shown that stabilization can affect isokinetic torque production. However, the effect of stabilization with hand-grip use has not been examined, and there are inconsistencies in the literature regarding its use. Fifteen men (mean age +/- SD = 24 +/- 3 years, height = 187 +/- 6 cm, mass = 84 +/- 10 kg) and 15 women (age = 25 +/- 4 years, height = 167 +/- 8 cm, mass = 62 +/- 6 kg) were tested on a Cybex 6000 dynamometer. Torque and joint angle signals, as well as quadriceps and hamstrings electromyographic (EMG) signals, were recorded during maximal knee flexion/extension at speeds of 60, 180, and 300 degrees x s(-1). Subjects performed the testing both with (stabilized) and without (nonstabilized with arms folded across the chest) hand-grip use. Repeated-measures analysis of variance (ANOVA) revealed a significant-motion (flexion, extension), X-condition (stabilized, non-stabilized) interaction in the data from the men in which hand-grip stabilization resulted in an 8.4% increase in knee extensor torque vs. a 0.2% increase in knee flexor torque. Stabilization did not significantly affect torque in women. The EMG analyses did not indicate a significant change in either agonist drive or antagonist cocontraction that accounted for the enhanced torque output with hand-grip use. This study found that hand-grip use enhanced knee extension maximal torque in men, but did not affect torque in women. The EMG data did not account for the changes in the torque data. Differences between men and women may have been due to mechanical factors and grip strength. These results indicate that hand-grip use needs to be considered when examining gender differences in knee strength and when studying knee flexion-extension ratios.

Adult↗

PubMed2004

Knee kinematics with a high-flexion posterior stabilized total knee prosthesis: an in vitro robotic experimental investigation.

BACKGROUND: An analysis of contemporary total knee arthroplasty reveals that, on the average, patients rarely flex the knee beyond 120 degrees. The biomechanical mechanisms that inhibit further flexion after total knee arthroplasty are unknown. The objective of the present study was to investigate the capability of a single design of a fixed-bearing, high-flexion posterior stabilized total knee arthroplasty system (LPS-Flex) to restore the range of flexion to that of the intact knee. METHODS: Thirteen cadaveric human knees were tested, with use of a robotic testing system, before and after total knee arthroplasty with the LPS-Flex prosthesis. The passive path and the kinematics under an isolated quadriceps force of 400 N, under an isolated hamstring force of 200 N, and with these forces combined were determined. Posterior femoral translation of the lateral and medial femoral condyles and tibial rotation were recorded from 0 degrees to 150 degrees of flexion. RESULTS: The medial and lateral condyles of the intact knee translated posteriorly from full extension to 150 degrees, reaching a mean peak (and standard deviation) of 22.9 +/- 11.3 mm and 31.9 +/- 12.5 mm, respectively, under the combined muscle forces. Following total knee arthroplasty, the amount of posterior femoral translation was lower than that observed in the intact knee. At 150 degrees, approximately 90% of the intact posterior femoral translation was recovered by the total knee replacement. Internal tibial rotation was observed for all knees throughout the range of motion. The cam-spine mechanism engaged at approximately 80 degrees and disengaged at 135 degrees. Despite the absence of cam-spine engagement, further posterior femoral translation occurred from 135 degrees to 150 degrees. CONCLUSIONS: The tibiofemoral articular geometry of the intact knee and the knee after total knee arthroplasty with use of the LPS-Flex design demonstrated similar kinematics at high flexion angles. The cam-spine mechanism enhanced posterior femoral translation only at the mid-range of flexion. The femoral component geometry of the LPS-Flex total knee prosthesis may improve posterior tibiofemoral articulation contact in high flexion angles.

Aged↗

PubMed1996

Effects of knee flexion angle at graft fixation on the outcome of anterior cruciate ligament reconstruction.

Clinical outcome in 44 patients who underwent anterior cruciate ligament (ACL) reconstruction with hamstring tendons augmented by the ligament augmentation device for chronic ACL deficiency was studied; average follow-up was 38 months (range, 24 to 52 months). In 19 patients, grafts were fixed with the knees at full extension (group 1), whereas in 25 patients, the grafts were fixed with the knees at 30 degrees of flexion (group 2). The results of subjective testing (Lysholm score), the Lachman test, the pivot-shift test, muscle strength testing, angle of extension loss, and follow-up arthroscopy were compared to assess the effects of flexion angle at fixation on stability and function. The range of motion in group 1 was significantly better than that in group 2. The stability of the knees and the arthroscopic appearance of the grafts in group 1 were, however, significantly worse than those in Group 2.

Adolescent↗

PubMed1999

Hamstring extensibility and transverse plane knee control relationship in athletic women.

Athletic women are at particular risk for sustaining a non-contact anterior cruciate ligament (ACL) injury. The hamstrings are vital to providing dynamic knee motion control in the sagittal and transverse planes during running stance, and some have suggested this function is enhanced when they are less extensible. This study attempted to determine the correlational relationships between hamstring extensibility and transverse plane knee kinematics and from these data to describe the dynamic transverse plane knee motion control capabilities of the hamstrings. Twenty normal athletic women (mean +/- SD; aged 21 +/- 1.6 years; height 163.3 +/- 5.7 cm; weight 60.1 +/- 3.6 kg) were evaluated for active hamstring extensibility and transverse plane knee kinematic relationships during crossover-cut stance phase. Following crossover-cut training (3 weeks) using the left (preferred) lower extremity as the stance limb, hamstring extensibility was measured. Following this, subjects were fitted with 9 retroreflective markers denoting the local segmental coordinate systems (3 markers each) of the left foot, leg and thigh. Kinematic (3-dimensional, four phase-locked cameras, 200 Hz) knee and ankle data were sampled and analyzed. Descriptive statistics and Pearson correlations between hamstring extensibility and knee and ankle kinematic variables were calculated. Statistical significance was set at P < or = 0.05 with Bonferroni adjustments. Hamstring extensibility (12 degrees +/- 8 degrees terminal extension) revealed low but significant positive correlations with tibial external rotation (6 degrees +/- 10.7 degrees) at heelstrike (19.3 degrees +/- 8.5 degrees knee flexion) (r = 0.62, P = 0.004) and tibial internal rotation (-13 degrees +/- 8.4 degrees) at peak knee flexion (57.8 degrees +/- 9.3 degrees) following heelstrike (r = 0.47, P = 0.01). Increased hamstring extensibility resulted in increased tibial external rotation at heelstrike and decreased tibial internal rotation at peak knee flexion. Increased hamstring extensibility may improve knee extensor efficiency at heelstrike by enabling greater tibial external rotation and protect the ACL at peak knee flexion by decreasing the tibial internal rotation magnitude.

Adult↗

PubMed2004

Comparison of tibial rotation strength in patients' status after anterior cruciate ligament reconstruction with hamstring versus patellar tendon autografts.

OBJECTIVE: To determine if there are tibial rotational strength deficits in individuals treated with a semitendinosus/gracilis or bone-patella tendon-bone (BTB) autografts for ACL reconstruction. DESIGN: Retrospective. SETTING: Clinical practice and nonprofit research site. PATIENTS: 102 subjects--34 treated with BTB autograft, 34 treated with a hamstring autograft, and 34 matched controls--were evaluated at an average of 53.1 +/- 36.0 months postoperatively. MAIN OUTCOME MEASUREMENTS: Isokinetic examination at 60, 120, and 180 degrees/s to assess internal (IT) and external tibial (ET) rotation peak torque of the operated knee and contralateral knee. Internal and external tibial rotation peak torque values were evaluated for differences between gender and surgery type (2 x 3 ANOVA). RESULTS: Contrasts of IT torque across groups revealed that surgery type exhibited a significant main effect (P < 0.0001), but gender did not (P = 0.07), and there was no interaction of surgery and gender (P = 0.64). The hamstring group was weaker in IT rotation compared with the BTB and control groups (P < 0.05). No difference was noted in IT rotation torque between BTB and control groups at all test velocities. Contrasts of ET rotation torque across groups revealed that surgery type exhibited a significant main effect (P < 0.0001), but gender did not (P = 0.48). There was no interaction of surgery and gender (P = 0.98). The BTB group was significantly weaker compared with the hamstring group (P < 0.001) and the control group (P < 0.001) in ET at all test velocities. CONCLUSIONS: Residual strength deficits in IT and ET rotation following hamstring graft and BTB graft ACL reconstruction are apparent.

Analysis of Variance↗

PubMed1979

[Fatigue fracture of the patella in cerebral palsy (author's transl)].

Amongst approximately 1 500 spastic children under treatment, the authors have seen three cases of fatigue fracture of the patella. One patient was spastic and two others were athetotic. The fatigue fractures can be explained by a flexed knee gait aggravated by a contracture of the hamstring tendons. No fracture was seen in patients treated by Egger's operation. It is concluded that this procedure both prevents and cures fatigue fracture of the patella.

Adolescent↗

PubMedDate not supplied

The hamstring index.

The purpose of this study was to assess the limits of hamstring tightness in 369 children by using three common tests. The straight leg-raise test averaged 100 degrees at birth, increasing to 110 degrees at age 1 year, before decreasing to 80 degrees by age 5-6 years. It then remained constant to skeletal maturity. Hamstring tightness is present if this angle is < 80 degrees in children younger than 2 years. After this age, the limit decreased steadily to plateau at 60 degrees by the age of 6 years. The popliteal angle measured the maximum 180 degrees from birth to age 2 years. This angle then decreased to average 155 degrees by age 6 years and remained steady. An angle < 125 degrees suggests significant hamstring tightness. The touching-toes test showed minimal variation between age groups averaging, 1 +/- 3 cm. Distances reached < -5 cm in children aged up to 6 years and < -15 cm in those older than 6 indicate excessively tight hamstrings. Little difference was seen between sides, although girls demonstrated less hamstring tightness. All tests showed a positive correlation with the grade of ligamentous laxity, but no association with the child's stage of puberty could be detected.

Adolescent↗

PubMed2004

Characterisation of the quadriceps stretch reflex during the transition from swing to stance phase of human walking.

The main objective of this study was to characterize the stretch reflex response of the human thigh muscles to an unexpected knee flexion at the transition from stance to swing during walking. Eleven healthy subjects walked on a treadmill at their preferred speed. Reliable and constant knee flexions (6-12 degrees amplitude, 230-350 degrees /s velocity, 220 ms duration) were applied during the late swing and early stance phase of human walking by rotating the knee joint with a specifically designed portable stretch apparatus affixed to the left knee. Responses from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), medial hamstrings (MH) and medial gastrocnemius (GM) were recorded via bipolar surface electromyograms (EMG). The onset of the response in the RF, VL and VM, remained stable and independent of the time in the step cycle when the stretch was applied. Across all subjects the response onset (mean +/- SD) occurred at 23+/-1, 24+/-1 and 23+/-1 ms for RF, VL and VM, respectively. The duration of the initial response was 90-110 ms, at which time the EMG signal returned towards baseline levels. Three reflex response windows, labelled the short latency reflex (SLR), the medium latency reflex (MLR) and the late latency reflex response (LLR), were analysed. The medium and late reflex responses of all knee extensors increased significantly ( p=0.008) as the gait cycle progressed from swing to stance. This was not related to the background EMG activity. In contrast, during standing at extensor EMG levels similar to those attained during walking the reflex responses were dependent on background EMG. During walking, LLR amplitudes expressed as a function of the background activity were on average two to three times greater than SLR and MLR reflex amplitudes. Distinct differences in SLR and LLR amplitude were observed for RF, VL and VM but not in the MLR amplitude. This may be related to the different pathways mediating the SLR, MLR and LLR components of the stretch response. As for the knee extensor antagonists, they exhibited a response to the stretch of the quadriceps at latencies short enough to be monosynaptic. This is in agreement with the suggestion by Eccles and Lundberg (1958) that there may be functional excitatory connections between the knee extensors and flexors in mammals.

Adult↗