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PubMedDate not supplied

Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament.

Reconstruction of the anterior cruciate ligament using the semitendinosus and gracilis tendons combined with the appropriate extraarticular procedures has been performed by the authors in 482 cases. In 321 cases both the semitendinosus and gracilis tendons were used and in 161 the semitendinosus alone. This retrospective study was done to determine if the use of these two tendons resulted in any significant loss of hamstring strength. Evaluation of quadriceps strength was also done as a measure of postoperative rehabilitation. Fifty-one patients with an average follow-up time of 26.2 months were tested on the Cybex machine (Cybex Co., Ronkonkoma, New York) by two examiners using the same technique. The examiners had not participated in the surgery or rehabilitation of these patients. In the reconstructed knee in which both semitendinosus and gracilis were used, hamstring strength was found to average 99% compared to the normal knee. When the semitendinosus alone was used there was no difference (102%) from the normal knee. Quadriceps strength in both groups averaged 96% in comparison to the normal quadriceps. These results confirm that no significant loss of hamstring strength occurred when the semitendinosus and gracilis tendons were used to construct the anterior cruciate ligament. Further, quadriceps strength of 96% as compared to the normal knee indicated a very acceptable degree of postoperative rehabilitation in this series.

Adolescent↗

PubMed1978

Knee muscular moment, tendon tension force and EMG during a vigorous movement in man.

With injuries to the components of the extensor apparatus of the knee as a background, it is interesting to investigate the magnitude of forces acting on these components, i.e. m. quadriceps femoris, the quadriceps tendon, patella, lig. patellae and tuberositas tibiae, during a vigorous but physiological movement. By means of the dynamic laws of mechanics the muscular moment of force with respect to the bilateral knee axis during kicking was calculated in 6 normal subjects. It was found that the maximum extending muscular moment in the knee occurs very early in the movement, when the initial flexion changes into extension, and thus long before the ball is hit. The peak of quadriceps EMG activity coincides with maximum moment. The EMG peak of the antagonistically acting hamstrings comes later, nearer to when the ball is struck. The greatest extending muscular moment obtained during the swing phase of kicking was surprisingly high, 260 Nm, corresponding to a tension force in the patellar tendon of 5200 N or about 7 times body weight. These values are discussed in relation to tendon strength.

Adult↗

PubMedDate not supplied

The effect of joint velocity on the contribution of the antagonist musculature to knee stiffness and laxity.

The electromyographic (EMG) coactivation patterns of the knee flexors and extensors when acting as antagonists were studied as a function of limb velocity to assess their contribution to joint stiffness and laxity. Normalized antagonist coactivation patterns developed from surface EMG recordings from the hamstrings and quadriceps during maximal effort isokinetic extension and flexion, respectively, demonstrated characteristic variations as the joint velocity increased from 15 deg/sec up to 240 deg/sec. The two-tailed t-test (P less than 0.01) was performed on the data obtained from eight normal knees. The results indicate that both hamstrings and quadriceps demonstrate a significant increase (greater than 100%) in their antagonist coactivation pattern during the final 40 degrees of fast extension and flexion movements, respectively, as limb velocity increases. A minor decrease in antagonist activity of the hamstrings (24%) and quadriceps (8%) was evident during the initial phase of the extension and flexion movements, respectively, as joint velocity increased. We concluded that as limb velocity is increased, there is a substantial reflexive (unintentional) increase in the contribution of the antagonist musculature to joint stiffness and reduction of laxity. The results also suggest that strength training of the hamstrings (rather than quadriceps) should be considered as a modality for conservative treatment of ACL deficiencies, as well as an adjunct to surgical reconstruction. Such training can also reduce the risk of high performance athletes in a reflexive manner by increasing joint stiffness.

Adult↗

PubMed2004

Tendon regeneration: an anatomical and histological study in sheep.

Utilization of the hamstring tendon in reconstruction of the anterior cruciate ligament (ACL) has become common in recent years. In MRI studies regeneration potential in harvested tendon has been observed. In the present study, 20 legs from ten sheep, which underwent 10 cm segment resection of tendon of musculus extensor digitalis lateralis (MEDL) were used. The sheep were killed 6 months after the operation and regenerated tendons were examined macroscopically and histologically. Dissection was performed in the tendon resection area and specimens were reharvested for histological examination. Regeneration of the tendon with normal anatomical topographies was found in all legs. Regeneration occurred on both sides of the resected tendon simultaneously. Regeneration was muscle-like in the proximal side but it was tendon-like in the distal side. The developed tendon was fused to the joint capsule and to the fascia at the joint line in all specimens. This study indicates that tendon has a potential for regeneration.

Animals↗

PubMed2006

Time-related changes in the cross-sectional area of the tibial tunnel after compaction of an autograft bone dowel alongside a hamstring graft.

PURPOSE: Extensive tunnel expansion in hamstring anterior cruciate ligament (ACL) reconstruction can complicate revision surgery. The purpose of this study was to examine our hypothesis that compaction of a bone dowel into the tibial tunnel reduces the cross-sectional area of the tunnel on the day of surgery and limits tunnel expansion to that of the cross-sectional area of the reamer at 4 months and 1 to 2 years. METHODS: A bone dowel averaging 23 mm in length and 7 mm in diameter was harvested from the tibial tunnel in 10 patients undergoing hamstring ACL reconstruction. The tibial tunnel was dilated, and the bone dowel was compacted anterior to the tendon graft. The cross-sectional area of the tibial tunnel was calculated on the day of surgery and at 4 months and 1 to 2 years postoperatively from computed tomography scans. RESULTS: On the day of surgery, the cross-sectional area of the tibial tunnel was 34% smaller than the 50-mm2 cross-sectional area of the 8-mm reamer used to drill the tunnel (P < .001). At 1 to 2 years, the cross-sectional area of the tibial tunnel was smaller than that of the reamer in 6 subjects, was slightly larger (53 to 56 mm2) in 3 subjects, and was substantially larger (80 mm2) in 1 subject. CONCLUSIONS: A surgeon who compacts an autogenous bone dowel into the tibial tunnel alongside a hamstring graft can expect little to no tunnel expansion in 90% of patients at 1 to 2 years. To our knowledge, the limitation of tunnel expansion to that of the cross-sectional area of the reamer has not been shown with other tibial fixation techniques. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Anatomy, Cross-Sectional↗

PubMed1999

Outcome of hamstring lengthening and distal rectus femoris transfer surgery.

To evaluate the outcome of hamstring lengthening and distal rectus femoris transfer, a retrospective study was performed comparing preoperative and postoperative gait analysis data from 16 children with neurologic involvement. Postoperatively, the timing of peak knee flexion during swing and the total arc of knee motion significantly improved. Hamstring range of motion and knee extension at terminal swing significantly improved, but stride length and gait velocity did not for the overall population. Patients who used braces postoperatively showed an improvement in stride length and velocity when wearing orthoses. This suggests that postoperative bracing may be needed in some patients to maximize the surgical outcome.

Adolescent↗

PubMed1995

Backward walking at three levels of treadmill inclination: an electromyographic and kinematic analysis.

Backward walking on a treadmill is a common tool for lower extremity rehabilitation in the clinical setting. The purpose of this study was to evaluate the adaptations in the gait cycle produced by walking backward on a treadmill at 0, 5, and 10% inclination. Sixteen healthy adult subjects (14 females, two males), mean age of 23.19 +/- 3.02, participated. Joint positions for hip, knee, and ankle were measured during a complete gait cycle. Values were time matched with average electromyographic (EMG) activity (surface electrode) of the rectus femoris, hamstrings, gastrocnemius, and anterior tibialis during each subphase of gait (initial contact, midstance, heel-off, and midswing). Values of joint position and average EMG were compared over the three treadmill conditions. Subjects walked for approximately 1 minute at 4.0 km/h. A simple repeated measures analysis of variance (p < .05) with a Duncan post hoc test was used to analyze for changes. Significant changes occurred in the joint positions of the knee and ankle at initial contact (ankle increased from 9.81 +/- 5.06 degrees to 13.08 +/- 3.68 degrees; knee increased from 30.94 +/- 5.25 degrees to 42.42 +/- 4.08 degrees) as the treadmill was raised from 0 to 10%. Significant changes occurred for average EMG activity for each muscle studied over the three treadmill conditions. The greatest changes occurred in the gastrocnemius at initial contact (increase from 189.76 +/- 44.29% to 293.09 +/- 79.16%) between the 0 and 10% conditions. The results of this investigation confirm that backward walking up an incline may place additional muscular demands on an individual.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Distal hamstring elongation in the management of spastic cerebral palsy.

Forty-nine children with spastic cerebral palsy treated by distal hamstring elongation and followed for an average of 4.4 years were reviewed. The aim of the operation was to release hamstring tightness to improve the patients' level of function and efficiency and the cosmetic appearance of their gait. Forty patients had significant improvement in gait pattern, and 18 had improved motor function. Complications included transient stiff-legged gait and exaggerated lumbar lordosis. One patient with spastic quadriceps had 15 degrees of persistent genu recurvatum.

Adolescent↗

PubMed1983

Flexion contractures of the knee following poliomyelitis.

Contractures of the knee after poliomyelitis are common in children in developing countries and treatment, particularly that of severe contractures, presents a surgical challenge. This paper describes a new method for correcting contractures of the knee. Mild contractures need manipulation only and a plaster cast. Moderate contractures are treated by a partial soft-tissue release of the hamstrings and fascia lata followed by gradual stretching of the remaining soft-tissues by manipulation and plaster. Where the contracture is severe, skeletal traction is used through Steinmans pins inserted into the tibia and os calcis. One hundred and thirty-six knees with varying degrees of contracture were treated by these methods. Full correction was achieved and then maintained by plaster immobilisation, physiotherapy and calipers. This prevented recurrence during an average follow-up period of two and a half years. The severity of the contracture of the knee was in direct proportion to the severity of associated flexion-abduction contractures at the hip and equinus deformity at the ankle, the degree of muscle imbalance. All of the contractures of the hip and some of the ankle (46.8%) needed simultaneous operative correction. The basic method is technically simple, requires no special equipment and the results recommend its use particularly in developing countries.

Adolescent↗

PubMed1988

Hamstring release for knee flexion contracture in spastic adults.

Thirty adults (17 male and 13 female patients) with spastic disorders were treated by hamstring releases of 46 extremities. The diagnoses were stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, and anoxia. The mean age at surgery was 38.6 years. Three extremities had partial release of the hamstring tendons behind the knee; the remaining 43 extremities had a complete release. The average position of the knee was 61.4 degrees of flexion preoperatively and 6 degrees postoperatively. The follow-up period averaged 21.3 months. Preoperatively, 87% of patients were nonambulatory. Following hamstring release 43% became ambulatory and 17% had gained the ability to transfer. Complications included two stroke patients with severe peripheral vascular disease; one developed a large nonhealing sore of the ankle and the other developed gangrene of the foot. Both patients required amputation. Three other patients developed recurrent flexion contractures that have since been rereleased with good results.

Adult↗

PubMed2004

Comparison of anterior cruciate ligament reconstruction in male and female athletes using the patellar tendon and hamstring autografts.

Despite the higher incidence of anterior cruciate ligament (ACL) injuries in female than in male athletes few authors have studied the effects of gender on the outcome of ACL reconstruction. This prospective study compared the results of ACL reconstruction using the patellar tendon and hamstring techniques in men and women. We prospectively followed 80 comparable athletes (46 males, 32 females) from a population of 287 patients operated on at our institution for ACL reconstruction using either patellar tendon or hamstring graft. There were 26 males and 14 females in the patellar tendon group, and 22 males and 18 females in the hamstring group. All patients were operated on by the same surgeon within 6 months from injury and underwent the same rehabilitation program at the same center. After an average of 36 months the patients were assessed by clinical evaluation, computerized knee laxity analysis, and isokinetic and functional strength tests; standard knee scores were also used. Among patellar tendon patients there were no significant differences between males and females regarding knee evaluation form, laxity, or isokinetic and functional tests. Females in the hamstring group had significantly greater laxity, and isokinetic tests at 1 year revealed a significantly higher deficit of peak torque at 60 degrees /s in flexion and extension. We suggest further studies on the clinical significance of these findings particularly on their possible ramifications in the areas of return to sports and rehabilitation of female athletes.

Adult↗

PubMed2001

Anterior cruciate ligament reconstruction in the immature athlete: long-term results of intra-articular reconstruction.

From 1986-1992, a total of 21 ACL reconstructions were completed in 20 skeletally immature athletes with an average age of 13.7 years (range: 11.8-15.6 years). Fifteen patients underwent operative reconstruction with hamstring tendons with wide open physes and 6 patients with bone-patellar tendon-bone (BPTB). All grafts were anatomically placed through transphyseal bone tunnels in the femur and tibia. Nineteen of 20 patients (20 of 21 reconstructions) returned for follow-up at an average of 34 months (range: 17-89 months). All patients had reached skeletal maturity at follow-up. No patient had limb-length discrepancy >1 cm postoperatively. No change in tibiofemoral alignment was noted (average 4.5 versus 4.25, P=.69). Modified Lysholm score was 93/95, and 19 of 20 athletes returned to preinjury level sports activity. Ligament laxity side-to-side difference was <3 mm in 16 patients, 3-6 mm in 2 patients, and >6 mm in 2 patients. One patient developed recurrent symptomatic laxity and was lost to follow-up. Two late graft ruptures (1 hamstring and 1 BPTB graft) occurred after major reinjury during sports. In this group of patients, ACL reconstruction through bone tunnels successfully eliminated instability although the failure rate, including late graft ruptures, was higher than that usually reported for adults. No limb length or angular deformity developed as a result of the transphyseal tunnels.

Adolescent↗

PubMed2003

Hamstring weakness as an indicator of poor knee function in ACL-deficient patients.

Anterior cruciate ligament (ACL) rupture causes instability to the knee joint which leads each patient to a different degree of disability. The purpose of this study was to examine the strength of the quadriceps and the hamstrings in ACL-deficient amateur soccer players at different levels of functional status. Thirty male amateur soccer players were separated into three groups according to their Lysholm score; the high-L1 (Lysholm > or =84), the intermediate-L2 (84> Lysholm > or =72) and the low-L3 (Lysholm <72) knee function groups. The control group consisted of 12 amateur soccer players. The strength of the quadriceps and hamstrings was assessed isokinetically at 60 degrees/s. The quadriceps demonstrated significant deficits of the injured knee compared to the intact knee in all groups, whilst the hamstrings showed significant weakness only in the low function group. Respective percentage deficits in groups L1, L2 and L3 were 13.7%, 16.0% and 18.6% for the quadriceps and 2.4%, 5.6% and 19.2% for the hamstrings. All groups had significant quadriceps weakness which did not differ between the groups. In contrast, the strength deficit of the hamstrings was an indicator of poor knee function, since they were significantly weak only in group L3, which represented patients who clearly failed to compensate for instability symptoms. In groups L1 and L2 the side-to-side differences were within the area of asymmetry measured in the control group. Clinical importance of the results is discussed.

Adult↗

PubMed2005

Central somatosensory changes associated with improved dynamic balance in subjects with anterior cruciate ligament deficiency.

To examine the mechanisms underlying return to pre-injury function in individuals with anterior cruciate ligament deficiency (ACL-D), we grouped 15 individuals (18-50 years of age) with ACL-D by functional status and strength (i.e. copers, non-copers and adapters) and compared measures of proprioception, somatosensory evoked potentials and neuromuscular responses to dynamic testing between groups. Seven subjects without ACL-D provided a comparative sample for dynamic balance testing (DBT). DBT consisted of bilateral EMG recordings of anterior tibialis, medial gastrocnemius, medial hamstrings and quadriceps during toes-down platform rotation. Relative latencies and relative amplitudes were calculated. Somatosensory evoked potential (SEPs) testing was based on identifying the presence or absence of the P27 potential. Proprioception was tested using threshold to detection of passive movement (TDPM). Those with the highest level of function, the copers, had a proprioceptive deficit, loss of P27 and altered postural synergies consisting of earlier and larger hamstring activation. Conversely, those with the lowest functional status, the non-copers, had strength and proprioception deficits, intact SEPs and inconsistent postural synergies. These results suggest that changes in central sensory representation may facilitate altered postural synergies that enable return to pre-injury functional status.

Adaptation, Physiological↗

PubMed2005

In-vivo sagittal plane knee kinematics: ACL intact, deficient and reconstructed knees.

Sagittal plane video fluoroscopy was used to analyse the bilateral knee kinematics of patients with unilateral ACL deficiency (ACLD) before, and 4 months after, hamstrings graft ACL reconstruction. Kinematics were studied during weight resisted knee extension, passive knee extension, and a step up. Thigh EMG records were also obtained from five subjects. In addition, six uninjured control subjects were analysed to establish normal kinematics. Kinematics were analysed by calculating the angle between the long axis of the tibia and the patella tendon through the range of knee flexion. Shear forces were calculated using a model of knee extension and force plate data. A maximum anterior TT of 7.3 (S.D. 2.1) mm was recorded in ACL intact (ACLI) knees during the weightbearing activity. Hamstrings activity was able to control ATT in the ACLD tibia to within the normal range of translation of the ACLI knee. Despite clinical improvements, ATT increased postoperatively in the reconstructed knees to 11.6 (S.D. 3.8) mm (P<0.048). The findings suggest that the ACL has only a minor role in the control of ATT during activity, and that the extent of ATT is more closely related to the level of quadriceps-generated shear force. A reduction in hamstrings force is proposed as the most likely cause for increased ATT post reconstruction. These findings have implications for the development of ACL rehabilitation regimes, and also may modify graft choice and the surgical aims of the procedure.

Adult↗

PubMed2001

Knee biomechanics of the dynamic squat exercise.

PURPOSE: Because a strong and stable knee is paramount to an athlete's or patient's success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, sports medicine physicians, researchers, coaches, and athletes who are interested in closed kinetic chain exercises, knee rehabilitation, and training for sport. The purpose of this review was to examine knee biomechanics during the dynamic squat exercise. METHODS: Tibiofemoral shear and compressive forces, patellofemoral compressive force, knee muscle activity, and knee stability were reviewed and discussed relative to athletic performance, injury potential, and rehabilitation. RESULTS: Low to moderate posterior shear forces, restrained primarily by the posterior cruciate ligament (PCL), were generated throughout the squat for all knee flexion angles. Low anterior shear forces, restrained primarily by the anterior cruciate ligament (ACL), were generated between 0 and 60 degrees knee flexion. Patellofemoral compressive forces and tibiofemoral compressive and shear forces progressively increased as the knees flexed and decreased as the knees extended, reaching peak values near maximum knee flexion. Hence, training the squat in the functional range between 0 and 50 degrees knee flexion may be appropriate for many knee rehabilitation patients, because knee forces were minimum in the functional range. Quadriceps, hamstrings, and gastrocnemius activity generally increased as knee flexion increased, which supports athletes with healthy knees performing the parallel squat (thighs parallel to ground at maximum knee flexion) between 0 and 100 degrees knee flexion. Furthermore, it was demonstrated that the parallel squat was not injurious to the healthy knee. CONCLUSIONS: The squat was shown to be an effective exercise to employ during cruciate ligament or patellofemoral rehabilitation. For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.

Adult↗

PubMedDate not supplied

Anatomical reconstruction of the patellar tendon: a new technique with hamstring tendons and iliotibial tract.

A new technique of patellar tendon reconstruction was performed in a patient who lost tendon and tibial tuberosity during wide excision surgery for a malignancy. In this procedure, the tendon was anatomically replaced by a graft composed of ipsilateral hamstring tendons and iliotibial tract, with the biomechanical conditions considered. Both ends of the graft were secured in the size-matched bone tunnels in the patella and tibia by screw post fixation, which is a technique established in ligament reconstruction surgery in the knee joint. At the twenty-month follow-up, the result was deemed successful.

Bone Neoplasms↗

PubMed1992

One-stage correction of the spastic dislocated hip. Use of pericapsular acetabuloplasty to improve coverage.

We performed a combined one-stage approach for the treatment of eighteen spastic subluxated or dislocated hips in eleven children who had cerebral palsy. All patients were between five and thirteen years old and had spastic subluxation or dislocation of the hip and severe acetabular dysplasia. The operation consisted of release of the adductors, psoas, and proximal hamstrings; a femoral-shortening varusderotation osteotomy; and a pericapsular pelvic osteotomy. The pelvic osteotomy was designed to increase superolateral coverage of the femoral head in the elongated acetabulum, which had erosion of the superior and lateral aspects. At the latest follow-up (mean duration, six years and ten months), seventeen of the eighteen hips remained anatomically reduced.

Acetabulum↗