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PubMedDate not supplied

Hamstring/quadriceps ratios in college football players: a high velocity evaluation.

Hamstring/quadriceps ratios were assessed on 60 intercollegiate football players at functional speeds of 90, 180, and 300 deg/sec on the Cybex II. The ratio rose as velocity of exercise increased and the quadriceps was stronger than the hamstrings at all speeds. The flexor/extensor ratio differed bilaterally at all speeds with ratio lower for the dominant knee. The study helped establish normative data on hamstring/quadricep ratios on football players at functional speeds. Furthermore, the ratio provides a guide to observe muscle imbalances which could be a factor in injury.

Adolescent↗

PubMed1977

Fragmentation of the distal pole of the patella in spastic cerebral palsy.

Of eighty-five consecutive patients, thirteen to twenty years old, with spastic cerebral palsy involving one or both extremities (thirty-five patients seen at one institution and fifty, at another), four had roentgenographic evidence of fragmentation of the distal pole of the patella. In addition, three other patients with six spastic lower extremities, four of them with patellar fragmentation, were also included. In these seven patients, there were nine knees with patellar fragmentation, twelve knees with patella alta, nine with a flexion contracture, five that were painful, and four with changes in the tibial tubercle resembling those found in Osgood-Schlatter disease. Excessive tension in the quadriceps mechanism, usually in the presence of a flexion contracture, appeared to cause the lesions. Four of the fragmented patellae healed after hamstring release and correction of the flexion deformity.

Achilles Tendon↗

PubMed2007

Functional assessment and muscle strength before and after reconstruction of chronic anterior cruciate ligament lesions.

PURPOSE: The goal of this study was to evaluate strength and functional capacity before and after anterior cruciate ligament (ACL) reconstruction to determine the influences of preoperative strength deficit, graft type, and gender, as well as their clinical relevance in predicting postsurgical recovery and determining the postoperative rehabilitation program. METHODS: This was a retrospective review of prospectively collected uniform data from a group of 191 patients undergoing ACL reconstruction. We assessed functional capabilities and strength of the quadriceps and hamstring at 60 degrees/s and 180 degrees/s by use of a Cybex II dynamometer (Lumex, Ronkonkoma, NY) before and 6, 9, and 12 months after surgery. RESULTS: There was a preoperative quadriceps strength deficit and a decreased limb symmetry index in patients with an ACL deficiency. This strength deficit increased postoperatively, with the highest measured deficit occurring at 6 months postoperatively and a clear improvement from 6 to 12 months. Functional assessment showed identical development. There was a statistically significant relation between an increased quadriceps strength deficit preoperatively and poor early postoperative functional performance. For the bone-patellar tendon-bone (BPTB) group, there was an increased quadriceps strength deficit compared with the semitendinosus and gracilis tendon (STG) group, and the STG group had an increased hamstring strength deficit on postoperative testing. The postoperative hamstring strength deficit is significantly increased in female patients. CONCLUSIONS: All of these data suggest that quadriceps strength deficit is related to the ACL injury and is increased by ACL reconstruction. Even 1 year after ACL reconstruction, a quadriceps strength deficit of almost 20% persists. Flexion strength is within the normal range before and after surgery. These results are influenced by graft choice, with a higher quadriceps strength deficit for BPTB grafts. STG grafts induce a higher hamstring strength deficit compared with BPTB grafts. Functional assessment is improved at 9 and 12 months postoperatively compared with preoperatively regardless of graft type. However, an increased preoperative quadriceps strength deficit results in a lower limb symmetry index at 6 and 9 months postoperatively. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Adolescent↗

PubMed2004

Dynamic simulation of FES-cycling: influence of individual parameters.

Cycling by means of functional electrical simulation (FES) is an attractive training method for spinal cord injured (SCI) subjects. FES-cycling performance is influenced by a number of parameters like seating position, physiological parameters, conditions of surface stimulation, and pedaling rate. The objective of this paper was the determination of the influence of the most important parameters on optimal muscle stimulation patterns and power output of FES-cycling on a noncircular pedal path. The rider-cycle system was modeled as a planar articulated rigid body linkage on which the muscle forces are applied via joint moments and implemented into a forward dynamic simulation of FES-cycling. For model validation, the generated drive torques that are predicted by the simulation were compared to measurements with an individual paraplegic subject. Then, a sensitivity analysis was carried out to determine the influences of the most important parameters for surface stimulation of gluteus maximus, quadriceps, hamstrings, and peroneus reflex. The results show how optimal stimulation patterns and the expected mean active power output can be estimated based on measured individual parameters and adjusted geometry and stimulation parameters for a particular SCI-subject. This can considerably improve FES-cycling performance and relieve the patients by shortening the time that is necessary for experimental adaptation of the stimulation patterns.

Adult↗

PubMed1996

Standing balance during internally produced perturbations in subjects with hemiplegia: validation of the balance scale.

OBJECTIVE: To examine the concurrent validity of the Berg Balance Scale (BBS) in subjects with hemiparesis after stroke by correlating functional balance performance on the BBS with laboratory measures of balance (center of pressure [CP] and electromyographic [EMG] activity of leg musculature during rapid arm flexion and during quiet stance). DESIGN: Concurrent validation study. Consistency of performance was determined through repeat measures obtained from 13 subjects. SETTING: Laboratory. PATIENTS: Twenty-four volunteers with longstanding hemiparesis from cerebrovascular accident (CVA) were tested. MAIN OUTCOME MEASURES: BBS scores were compared with CP excursion speed during (1) self-initiated rapid unilateral arm flexion with the nonhemiplegic arm and (2) quiet stance. The peak tangential arm acceleration and the sequence of EMG events in the posterior leg muscles were monitored during the arm flexion movement. RESULTS: In the arm flexion condition, BBS performance was significantly correlated with arm acceleration and CP excursion speed (multiple regression R = .81). BBS performance was also related to the presence of anticipatory activation of ipsilateral hamstrings during the rapid arm flexion movement. BBS performance and CP excursion speed during quiet stance were also significantly related (r = .76). The initial and repeat measures were not significantly different in magnitude (paired tests of difference, p < .01). CONCLUSION: The BBS appears to reflect differing abilities to tolerate the internally produced perturbation to standing balance associated with forward arm flexion in individuals with hemiparesis from CVA.

Aged↗

PubMed2004

Outcome of anterior cruciate ligament reconstruction using quadriceps tendon autograft.

PURPOSE: The purpose of this study was to determine the outcome of anterior cruciate ligament (ACL) reconstruction using a quadriceps tendon autograft. TYPE OF STUDY: A case series of patients who had received arthroscopic ACL reconstructions using quadriceps tendon autograft was retrospectively evaluated. METHODS: Sixty-seven ACL reconstructions were evaluated at a mean of 41 months (range, 27 to 49 months). Clinical assessment was made using a modified Lysholm score, documentation of International Knee Documentation Committee (IKDC), the anterior knee pain questionnaire of Shelbourne and Trumper, and by KT-2000 arthrometric analysis. Isokinetic strength testing and radiographic assessments were also performed. RESULTS: Arthrometric analysis showed that 63 knees (94%) were graded A or B with a median laxity of 2 mm postoperatively. The Lysholm score improved postoperatively from 71 to 90 ( P < or = .05). Extension peak torque of the quadriceps muscle recovered to 82% and 89% of that of the contralateral knee at 180 degrees/second at 1 year and 2 years after surgery, respectively. The patellar position in terms of congruence angle and Insall-Salvati ratio did not show any significant change. Only 4 patients complained of moderate pain on kneeling and 1 patient complained of harvest-site tenderness. CONCLUSIONS: ACL reconstruction using a quadriceps tendon autograft showed satisfactory results with reduced donor-site morbidities. The quadriceps tendon can be a reliable source of graft, and is comparable to bone-patellar tendon-bone or hamstring tendon in ACL reconstruction. LEVEL OF EVIDENCE: Level IV, Case Series (no, or historical, control group).

Adolescent↗

PubMed1988

The dorsal column projection of muscle afferent fibres from the cat hindlimb.

1. The extent of the projection of hindlimb muscle afferent fibres ascending the dorsal columns has been studied in barbiturate-anaesthetized cats. This has been investigated using electrical stimulation of the dorsal columns at different spinal levels while recording from (i) peripheral muscle nerves, and (ii) single muscle afferent fibres within the dorsal columns. These two approaches have produced complementary results. 2. The conduction velocity of both group I and group II afferent fibres decreased progressively after entering the dorsal columns. 3. The majority of group I and group II fibres project at least as far as L2 but leave the dorsal columns at or before the lower thoracic segments. 4. By taking advantage of the lower electrical threshold of Ia compared to Ib fibres in the hamstring nerves, it could be shown that both Ia and Ib fibres leave the dorsal columns at similar locations. 5. A small number of afferent fibres were found to project to C1. On the basis of previous work it is likely that such fibres originate from Pacinian or paciniform corpuscles.

Action Potentials↗

PubMed2003

Lumbar disc herniation and tight hamstrings syndrome in adolescence.

BACKGROUND: Lumbar intervertebral disc herniation is infrequently encountered in children and adolescents. Additional signs and symptoms such as postural deformities and abnormal gait accompany the classical findings of lumbar root irritation. These unusual signs have been described in the literature as "tight hamstrings syndrome". Waddling gait with flexed knees is considered as pathognomonic for this condition and may be masked by the signs of root irritation due to prolapsed intervertebral disc material. CASE REPORT AND DISCUSSION: We report an adolescent patient with lumbar disc herniation in whom gait abnormality and limitation of lumbar movements persisted after surgical intervention. A review of the literature on tight hamstrings is presented.

Adolescent↗

PubMed2001

Treatment of knee contracture in cerebral palsy by hamstring lengthening, posterior capsulotomy, and quadriceps mechanism shortening.

Results of surgery to correct fixed flexion contracture of the knee and improve voluntary knee extension in 39 knees in 20 children (11 females, 9 males; mean age 12 years 8 months, age range 5 to 20 years) with cerebral palsy were analyzed. All patients had neuromotor disease and 18 children had spastic diplegia or quadriplegia. All patients could initiate voluntary knee extension but lacked full passive extension. Five patients (10 knees) were free walkers with a mean motor severity index of 19 and mean fixed knee contracture of 20 degrees. Fifteen patients (29 knees) were not free walkers and 13 were wheelchair ambulators. They had a mean motor severity index of 8 and mean fixed knee contractures of 30 degrees. Surgical procedures included various combinations of hamstring lengthening and/or posterior capsulotomy to allow free passive knee extension, with or without quadriceps mechanism shortening, to enhance voluntary extension. The best results were in patients who had hamstring lengthening, posterior capsulotomy, and quadriceps mechanism shortening.

Adolescent↗

PubMed1997

Selective dorsal rhizotomy and rates of orthopedic surgery in children with spastic cerebral palsy.

If the spasticity of cerebral palsy (CP) is reduced in children at a young age by selective dorsal rhizotomy, the incidence of lower-extremity deformities requiring orthopedic surgery may be reduced; however, this has never been investigated in detail. The authors examined the effects of selective dorsal rhizotomy on rates of lower-extremity orthopedic surgery in 178 children with CP. Age at selective dorsal rhizotomy ranged from 2 to 19.3 years (mean 5.5 years) with follow-up intervals ranging from 24 to 70 months (mean 44 months). Spastic CP was classified as quadriplegia (33%), diplegia (65%), and hemiplegia (2%). To assess the effects of early versus late rhizotomy on rates of orthopedic surgery, patients were grouped as follows: Group I underwent rhizotomy between 2 and 4 years of age (54 patients), and Group II underwent rhizotomy between 5 and 19 years of age (124 patients). Comparison of Kaplan-Meier plots of lifetime orthopedic surgery rates revealed that Group II underwent orthopedic surgery at a higher rate than Group I (p = 0.037). Analysis by procedure type revealed higher orthopedic surgery rates in Group II than Group I for heel cord releases (p = 0.0025), adductor releases (p = 0.018), and hamstring releases (p = 0.02). Orthopedic surgery rates were no higher for Group II compared to Group I for ankle/foot operations (p = 0.023), femoral osteotomy (p = 0.25), iliopsoas releases (p = 0.35), and "other" operations (p = 0.013). The data indicate that early rhizotomy reduces the need for orthopedic surgery for heel cord, hamstring, and adductor releases.

Adolescent↗

PubMed2004

Control of frontal plane knee laxity during gait in patients with medial compartment knee osteoarthritis.

OBJECTIVE: Patients with medial compartment knee osteoarthritis (OA) adopt an abnormal gait pattern, and often develop frontal plane laxity at the knee. The purpose of this study was to quantify the extent of frontal plane knee joint laxity in patients with medial knee OA and genu varum and to assess the effect of joint laxity on knee joint kinetics, kinematics and muscle activity during gait. DESIGN: Twelve subjects with genu varum and medial compartment knee osteoarthritis (OA group) and 12 age-matched uninjured subjects underwent stress radiography to determine the presence and magnitude of frontal plane laxity. All subjects also went through gait analysis with surface electromyography of the medial and lateral quadriceps, hamstrings, and gastrocnemius to calculate knee joint kinematics and kinetics and co-contraction levels during gait. RESULTS: The OA group showed significantly greater knee instability (P = 0.002), medial joint laxity (P = 0.001), greater medial quadriceps-medial gastrocnemius (VMMG) co-contraction (P = 0.043), and greater knee adduction moments (P = 0.019) than the control group. Medial joint laxity contributed significantly to the variance in both VMMG and the knee adduction moment during early stance. CONCLUSION: The presence of medial laxity in patients with knee OA is likely contributing to the altered gait patterns observed in those with medial knee OA. Greater medial co-contraction and knee adduction moments bodes poorly for the long-term integrity of the articular cartilage, suggesting that medial joint laxity should be a focus of interventions aimed at slowing the progression of disease in individuals with medial compartment knee OA.

Adult↗

PubMed2006

Biomechanical differences exhibited during sit-to-stand between total knee arthroplasty designs of varying radii.

The purpose of the study was to investigate the influence of the mechanical differences between a single-radius total knee arthroplasty (SR TKA) and a multi-radius (MR) TKA design on the functional performance during a sit-to-stand movement. Three-dimensional kinematics and electromyography for selected knee flexor and extensor muscles were obtained for 16 (8 SR and 8 MR) unilateral, posterior-stabilized TKA participants. Compared to the SR group, the MR group demonstrated compensatory adaptations, with increases in performance time, trunk flexion displacement and velocity, and knee extensor electromyography; and greater relative hamstring co-activation of the MR limbs was needed to increase joint stability. An initial knee abduction displacement was exhibited by more MR than SR participants. In conclusion, SR TKA provides functional benefits to patients.

Aged↗

PubMed1999

Botulinum toxin A in hamstring spasticity.

Hamstring injection of Botulinum toxin A (BtA) may have a role in the conservative management of flexed knee gait in cerebral palsy or in simulating the effect of surgery. Ten children who were likely to require future hamstring lengthening were injected. Short term outcome was assessed by clinical examination and 3-D gait analysis. Mean popliteal angle decreased by 16 degrees and maximum knee extension in stance increased by 8 degrees, the latter relapsing by 12 weeks. Mean pelvic tilt tended to increase suggesting that isolated hamstring weakening be approached with caution. Energy cost of walking was not significantly changed in six of the ten patients. A small increase in knee extension in stance was often associated with patient satisfaction. There are theoretical grounds for expecting an associated increased longitudinal muscle growth after BtA injection.

Botulinum Toxins, Type A↗

PubMed1976

Tenderness at motor points. A diagnostic and prognostic aid for low-back injury.

In patients with low-back injury the motor points of some muscles may be tender. Of fifty patients with low-back "strain", twenty-six had tender motor points and twenty-four did not, while forty-nine of fifty patients with radicular signs and symptoms suggesting disc involvement had tender motor points, and the one without such tender points had a hamstring contusion which limited straight leg raising. Of fifty controls with no back disability, only seven had mild tender points after strenuous activity, while forty-six of another fifty controls with occasional back discomfort had mild motor-point tenderness. In all instances the tender motor points were located in the myotomes corresponding to the probable segmental levels of spinal injury and of root involvement, when present. Patients with low-back strain and no tender motor points were disabled for an average of 6.9 weeks, while those with the same diagnosis but tender motor points were disabled for an average of 19.7 weeks, or almost as long as the patients with signs of radicular involvement, who were disabled for an average of 25.7 weeks. Tender motor points may therefore be of diagnostic and prognostic value, serving as sensitive localizers of radicular involvement and differentiating a simple mechanical low-back strain from one with neural involvement.

Adult↗

PubMedDate not supplied

Predictive leg strength values in immediately prepubescent and postpubescent athletes.

Sixty healthy, athletic children were treated on a Cybex II Dynamometer to obtain values for the relative strengths of the major muscle groups of the lower extremity. Prepubescent and postpubescent boys and girls were tested. Of the anthropometric parameters measured, lean body weight correlated best with maximal torque force development. In prepubescent children, the mean maximal quadriceps torque force, measured in foot-pounds at 60 deg/sec, is equal to 70% of the lean body weight. In postpubescent subjects, the mean peak quadriceps torque equalled 80% of the lean body weight in girls and 90% of the lean body weight in boys. Correlations can be established between the maximal torque force generated by the quadriceps and the strength of the hamstrings, ankle dorsiflexors, and plantar flexors. The values obtained are useful in planning training and rehabilitation programs and in determining when an injured young athlete can safely return to his or her sport.

Adolescent↗

PubMed1988

Relationship between peak torque and total work in an isokinetic contraction of the medial collateral ligament insufficient knee.

The aim of this study was to assess the relationship between the isometric and isokinetic peak torques (speed of movement 0, 60, and 180 degrees/s) and the total work output of multiple contractions (180 degrees/s) of the quadriceps and hamstrings in 25 subjects having a chronic, complete insufficiency of the medial collateral ligament of the knee. At every test speed the Pearson product moment (r) and the Spearman rank (rs) correlation coefficients between the peak torque and total work were highly significant for both muscle groups in the uninjured (r = 0.75-0.96, rs = 0.72-0.95) as well as in the medially unstable (r = 0.79-0.93, rs = 0.76-0.92) knees. In both knees and in both muscle groups, the correlation coefficients increased toward the highest speed of the isokinetic movement, obviously since the total work was registered at that speed. The author concludes that in the medial collateral ligament insufficient knees the total work analysis offers little additional information to that attained by more simple measurement, the peak torque analysis.

Adult↗

PubMed2000

Validity of the modified back-saver sit-and-reach test: a comparison with other protocols.

PURPOSE: Studies have shown that the classical sit-and-reach (CSR) test, the modified sit-and-reach (MSR), and the newly developed back-saver sit-and-reach (BS) test have poor criterion-related validity in estimating low-back flexibility but yielded moderate criterion-related validity in hamstring flexibility. The V sit-and-reach (VSR) test was found to be practical but the validity has not been established. The purpose of this study was to propose a modified back-saver sit-and-reach (MBS) test, which incorporated all advantages of the various protocols, and to compare the criterion-related validity and reliability of all these tests. METHODS: 158 college students (F = 96, and M = 62; age = 20.77 +/- 2.51) performed CSR, VSR, BS (left and right leg), and MBS (left and right leg) tests in a randomized order. Scores from each test were then correlated with the criterion measures. RESULTS: For all sit-reach tests, intraclass reliability (single trial) was very high (r = 0.89-0.98). MBS yielded significant and highest r with low-back and hamstring criterion for men (r = 0.47-0.67) and women (r = 0.23-0.54). The low-back and right hamstring validity of MBS for men were significantly (P < 0.01) higher than those from BS and CSR, whereas no differences in criterion-related validity were found between the MBS and other protocols in women. The ratings of perceived comfort among the sit-and-reach protocols were significantly different (P < 0.001) from each other. The rating for MBS was observed the most comfortable test as compared with other protocols. CONCLUSION: The MBS test is not only a reliable test for hamstring and low-back flexibility, it is also a more practical with improved validity for hamstring and low-back flexibility in men than previous protocols.

Adolescent↗

PubMed2005

Dynamic soft tissue mobilisation increases hamstring flexibility in healthy male subjects.

OBJECTIVES: The purpose of this study was to investigate the effect of dynamic soft tissue mobilisation (STM) on hamstring flexibility in healthy male subjects. METHODS: Forty five males volunteered to participate in a randomised, controlled single blind design study. Volunteers were randomised to either control, classic STM, or dynamic STM intervention. The control group was positioned prone for 5 min. The classic STM group received standard STM techniques performed in a neutral prone position for 5 min. The dynamic STM group received all elements of classic STM followed by distal to proximal longitudinal strokes performed during passive, active, and eccentric loading of the hamstring. Only specific areas of tissue tightness were treated during the dynamic phase. Hamstring flexibility was quantified as hip flexion angle (HFA) which was the difference between the total range of straight leg raise and the range of pelvic rotation. Pre- and post-testing was conducted for the subjects in each group. A one-way ANCOVA followed by pairwise post-hoc comparisons was used to determine whether change in HFA differed between groups. The alpha level was set at 0.05. RESULTS: Increase in hamstring flexibility was significantly greater in the dynamic STM group than either the control or classic STM groups with mean (standard deviation) increase in degrees in the HFA measures of 4.7 (4.8), -0.04 (4.8), and 1.3 (3.8), respectively. CONCLUSIONS: Dynamic soft tissue mobilisation (STM) significantly increased hamstring flexibility in healthy male subjects.

Adolescent↗