Hamstring control and the unstable anterior cruciate ligament-deficient knee.
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Adult↗
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Contralateral hamstring (biceps femoris) coactivation patterns and anterior cruciate ligament dysfunction.
It has been postulated that coactivation of antagonist hamstring musculature during active knee extension aids the anterior cruciate ligament (ACL) in maintaining joint stability by exerting an opposing torque to anterior tibial displacement induced by the quadriceps. It was the purpose of this study to compare contralateral patterns of hamstring coactivation in subjects who have suffered ACL dysfunction with subjects who have normal knees. Five subjects who had suffered ACL dysfunction (INJ) and five uninjured (UNI) subjects performed maximal flexions and extensions of the knee on a modified isokinetic dynamometer at 100 degrees and 300 degrees.s-1. Simultaneous recordings of torque, angular displacement, and electromyographic (EMG) activity from the hamstring musculature were computer processed. No significant differences (P < 0.05) in torque were found between ACL/normal and right/left limbs for the INJ and UNI groups, respectively. For the INJ subjects, mean coactivation of the normal limb hamstrings during extension averaged twice that of the ACL limb. In contrast, no significant difference was found for the same comparison between right and left limbs in the UNI group. The results of this study suggest that asymmetry in hamstring coactivation during knee extension may result from ACL dysfunction.
Adult↗
Arthroscopic reconstruction of the posterior cruciate ligament with use of a quadruple hamstring tendon graft with 3- to 5-year follow-up.
PURPOSE: This study prospectively evaluated 20 patients treated consecutively to determine patient outcomes, efficacy, and complication potential of arthroscopically assisted posterior cruciate ligament (PCL) reconstruction performed with hamstring tendon grafts. METHODS: Twenty patients (15 men and 5 women), each with an isolated PCL injury, underwent PCL reconstruction with hamstring tendon autograft and were enrolled in this prospective study. Average age at time of surgery was 29 years (range, 20 to 57 years). Average time from injury to surgery was 4 months (range, 3 to 12 months). Average follow-up period was 40 months (range, 36 to 50 months). Patients underwent regular follow-up after clinical and radiographic preoperative and postoperative evaluation. Follow-up examinations comprised the Lysholm Knee Score, the Tegner Activity Score, the International Knee Documentation Committee (IKDC) score, thigh muscle assessment, and radiographic evaluation. RESULTS: Mean preoperative Lysholm score for 20 knees was 63 +/- 10 (range, 48-73); mean postoperative Lysholm score was 93 +/- 9 (range, 77-100). Eighteen of 20 patients (90%) showed good or excellent results at final assessment. Mean preinjury and preoperative Tegner scores were 7 +/- 1.5 (range, 5-9) and 3 +/- 1.9 (range, 2-5), respectively; mean postoperative Tegner score for 20 knees was 6.3 +/- 2.4 (range, 4-9). In final IKDC ratings, 85% of patients (17 of 20) were assessed as normal or near normal (grade A or B). A statistically significant improvement was seen in thigh girth difference, extensor strength ratio, and flexor strength ratio before and after reconstruction at a minimum of 3 years of follow-up. CONCLUSIONS: After follow-up for longer than 36 months, analytical results showed satisfactory function after PCL reconstruction with the use of hamstring tendon autografts. We suggest that the hamstring tendon autograft is a safe, effective, and acceptable choice for PCL reconstruction, and that it affords good ligament reconstruction. LEVEL OF EVIDENCE: IV, therapeutic case series.
Adult↗
Arthroscopic posterior cruciate ligament reconstruction with hamstring tendon autograft: results with a minimum 4-year follow-up.
This study prospectively evaluates the outcomes at a minimum 4-year follow-up after PCL reconstruction using quadruple hamstring tendon autograft with an arthroscopic double fixation technique. During 1996-1999, hamstring tendon autograft graft has been used in 57 patients. Data from 52 patients who had been followed up completely were analyzed. All patients suffered from a grade 3 or higher grade of posterior drawer test and posterior sag sign with MRI image confirmation. Twelve knees had combined posterior and posterolateral instability, which were simultaneously reconstructed. Clinical assessments included Lysholm knee score, International Knee Documentation Committee (IKDC) scores, KT-1000 instrumented test, thigh muscle assessment, and radiographic evaluation. The mean Lysholm score was 54 (40-65) and 91 (65-100) points (P<0.01) before and after surgery. Thirty (58%) patients could return to moderate or strenuous activity. The evaluation of AP translation has been performed with KT-1000. The average posterior displacement measured with KT-1000 was 11.69+/-2.01 mm preoperatively and 3.45+/-2.04 mm postoperatively. Forty-two (81%) patients demonstrated ligament laxity of less than 5 mm. Forty-two (81%) patients were rated as normal or nearly normal based on IKDC scores. Forty-six (88%) patients achieved a minimum of 80% recovery of extensor strength and 44 (85%) patients achieved a minimum of 80% recovery of flexor strength. Statistically significant differences existed in thigh girth, extensor strength, and flexor strength before and after reconstruction. Arthroscopic reconstruction for PCL with four-strand hamstring tendon graft produced satisfactory results. The semitendinosus and gracilis tendon graft is adequate in graft size, technically easier to perform and more reproducible, and had a satisfactory result.
Adult↗
Changes in muscular activity after knee arthrotomy and arthroscopy.
The object of this study was to find out whether an arthrotomy of the knee would damage joint proprioception. Twenty patients who underwent arthrotomy, and 20 patients after arthroscopy, were tested on a modified ergometer and the electromyographic action of their quadriceps and hamstrings recorded. The quadriceps action started later and had a shorter duration (20 ms) after arthrotomy. The differences are statistically significant in intra-individual comparison both for vastus lateralis and medialis, in comparison with the normal group for only the vastus medialis. There were no significant differences in muscle control after arthroscopy. These results are in favor of preferring arthroscopy to arthrotomy whenever possible.
Adult↗
Development of a strength test battery for evaluating leg muscle power after anterior cruciate ligament injury and reconstruction.
A more sports-specific and detailed strength assessment has been advocated for patients after anterior cruciate ligament (ACL) injury and reconstruction. The purpose of this study was to develop a test battery of lower extremity strength tests with high ability to discriminate between leg power development on the injured and uninjured sides in patients after ACL injury and in patients who have undergone ACL reconstruction. Twenty-three patients were tested 6 months after ACL injury and 44 patients were tested 6 months after ACL reconstruction. Twenty-four of the 44 patients were operated on using a hamstrings graft and 20 patients were operated on using a patellar tendon graft. All the patients performed a test battery of three strength tests for each leg in a randomised order. The three strength tests were chosen to reflect quadriceps and hamstring muscular power in a knee-extension and a knee-flexion test (open kinetic chain) and lower-extremity muscular power in a leg-press test (closed kinetic chain). There was a higher sensitivity for the test battery to discriminate abnormal leg power compared with any of the three strength tests individually. Nine out of ten patients after ACL reconstruction and six out of ten of the patients after ACL injury exhibited abnormal leg power symmetry using the test battery. Thus, this test battery had high ability in terms of discriminating between the leg power performance on the injured and uninjured side, both in patients with an ACL injury and in patients who have undergone ACL reconstruction. It is concluded that a test battery consisting of a knee-extension, knee-flexion and leg-press muscle power test had high ability to determine deficits in leg power 6 months after ACL injury and reconstruction. Only a minority of the patients had restored leg muscle power. The clinical relevance is that the test battery may contribute to the decision-making process when deciding whether and when patients can safely return to strenuous physical activities after an ACL injury or reconstruction.
Adult↗
EMG biofeedback assisted KT-1000 evaluation of anterior tibial displacement.
Two studies were undertaken to evaluate the use of EMG biofeedback to encourage hamstring relaxation during KT-1000 measurement of anterior tibial displacement. In study 1, 60 ACL-deficient patients were studied in three groups using 15 lb and 20 lb in each group: in group 1 the patients were simply retested 15 min after the initial test sequence, in group 2 they were initially retested with EMG biofeedback and then again without, and in group 3 they were retested twice with EMG biofeedback. No significant difference in mean anterior tibial displacement was seen between the initial measurements and retest measurements when no EMG biofeedback was used. A significant increase in mean anterior tibial displacement was seen when the retesting was performed with EMG biofeedback. No further increase was seen with repeated retesting with EMG biofeedback. In study 2, 40 patients were evaluated 4-12 months following ACL reconstruction. KT-1000 measurements of anterior tibial displacement of both the operated and non-operated knees were made at 15 lb and 30 lb with and without the use of EMG biofeedback. EMG biofeedback was associated with a significant increase in unilateral measurement of anterior tibial displacement. When side-to-side differences were compared, there was a small but statistically significant increase in anterior tibial displacement with the use of EMG biofeedback. Although the use of EMG biofeedback to encourage hamstring relaxation does increase unilateral measurements of anterior tibial displacement, it does not appear to have a clinically significant effect on measurement of side-to-side difference. It may have a role in testing patients who have difficulty achieving hamstring relaxation or in aiding inexperienced examiners.
Adult↗
Biomechanical assessment of the effects of significant hamstring injury: an isokinetic study.
Soccer players may develop recurrent hamstring injuries. This may be due to inadequate rehabilitation or to recurrent injury. In addition, following injury, the hamstring muscular complex may be permanently damaged, resulting in decreased strength, and increased likelihood of recurrent injury. Fourteen professional soccer players were assessed by clinical examination and by isokinetic testing with a Cybex II machine. Seven had suffered moderate or major hamstring injuries in the past year. There were seven controls. None of the hamstring group were currently suffering from an acute hamstring injury. The results of the two groups were compared. There were no differences in the mean results. This pilot study suggests that no permanent functional damage occurs to the muscular complex after moderate or major hamstring injuries after correct treatment. However, further research is required to confirm this.
Adolescent↗
Arthroscopy-assisted anterior cruciate ligament reconstruction with patellar tendon or hamstring autografts.
Isolated ACL reconstructions were performed in 138 patients between 1994 and 1998. Patellar bone-patellar tendon-bone, and hamstring tendon autografts were used in 88 patients, and allografts were used in 50 patients. Eighty-eight knees of 88 patients with autograft reconstructions (17 female, 71 male) were included in this study and evaluation of the patients with allograft reconstruction reported separately. The mean age at the time of the operation was 32 years. All ACL reconstructions were performed arthroscopically. Twenty-seven bone-patellar tendon-bone, and 61 hamstring tendon autografts were used. The mean follow-up was 29 months. In the postoperative course the Lachman test was negative in 62 patients, 1+ in 22 patients, and 2+ in 4 patients. In 17 patients, anterior drawer sign were 1+ in comparison to the contralateral side. Pivot shift test was moderately positive only in 5 cases in the bone-patellar tendon-bone and hamstring tendon autograft groups postoperatively. There were 3 patients with subjective "giving way" symptoms. Second look arthroscopy revealed rupture of the neo-ligament. Arthroscopic washout and debridement were performed, and no revision ligamentoplasties were performed. Two of these patients improved with accelerated proprioceptive physical therapy, and one had to decrease his previous level of activity. There were no cases of arthrofibrosis, infection, or extension lag. Clinical results of patellar bone-tendon-bone and hamstring groups did not show any significant clinical difference. Avoiding the disturbance of the extensor mechanism of the knee is probably the most significant advantage of the hamstring autograft.
Adult↗
[Complete rupture of the tendon of the biceps muscle of the thigh].
Complete rupture of the tendon of the M. biceps femoris proximal to its insertion is a rare occurrence. Relatively few patients have been recorded. We describe a patient with a complete rupture sustained as a result of a water skiing accident, viz. a fall over the stern wave. The case history was in accordance with a theory about the cause of this lesion--sudden overstretching of the hamstrings. The diagnosis was made by physical examination in the acute phase. With the patient in supine, 90 degrees flexed knees position and with isometric contraction of his hamstrings it is easy to mark and palpate a defect of the tendon just proximal to the caput fibulae. After operative reconstruction, a plaster cylinder was used for five weeks' postoperative immobilization. Five weeks after surgery, physical therapy was started, first to regain knee motion, and later to regain strength. Twelve weeks after surgery, the patient resumed working and recreational sports.
Athletic Injuries↗
Complete avulsion of the hamstring tendons from the ischial tuberosity. A report of two cases sustained in judo.
Rupture of the hamstring tendon is a rare injury. Two cases of complete rupture of the hamstring tendons sustained while playing judo are reported. The diagnosis of a rupture of the hamstring tendons was difficult from physical examination because of severe pain on knee or hip joint movement. Magnetic resonance imaging was non-invasive and showed the lesion clearly. In one of these two cases the less satisfactory results of non-operative treatment were clearly shown in both isokinetic muscle force evaluation and sports activities.
Adult↗
The distribution of injuries in men's Canada West university football. A 5-year analysis.
We conducted a prospective cohort study from 1993 to 1997 to determine the frequency and severity of injury in men's Canada West university football. The Canadian Intercollegiate Sport Injury Registry was used to document baseline preseason data, daily athlete participation, and subsequent injury from five varsity football teams. An injury was defined as "any injury resulting in one or more complete or partial sessions of time loss" or "any concussion or transient neck neurologic injury." The annual proportion of injured athletes ranged from 53.5% to 60.4%, with a 5-year total of 1,811 injuries. Regression analysis indicated that the rate of nonconcussion, nonneck neurologic injuries increased. Concussion (N = 110), hamstring strain (N = 88), and brachial plexus (N = 84) injuries were the most common, specific injury diagnoses. Knee injuries resulted in the highest rate of severe (greater than or equal to 7 sessions of time loss) injury and resulted in the most time loss (3,350.5 sessions). Ligament sprains and muscle strains and spasms accounted for approximately half of all injury diagnoses. A total of 1,173 injuries (65%) were related to contact between players or between players and other obstacles. Future studies should be conducted to identify risk factors for the ultimate purpose of implementing injury prevention strategies.
Adolescent↗
Quadriceps protects the anterior cruciate ligament.
The aim of this study is to show that the quadriceps is the primary muscular restraint to anterior tibial translation during closed kinetic chain activities such as running, jumping, walking, and standing. It is my hypothesis that the quadriceps vector is directed superiorly during open kinetic chain knee extension and inferiorly during closed kinetic chain knee extension. My methods involve vector analysis based on a lateral radiograph of the normal human knee and muscle ultrasound. My results show that the quadriceps vector is directed superiorly for open kinetic chain knee extension and inferiorly for closed kinetic chain knee extension. The inferiorly directed quadriceps vector has an anterior femoral-tibial or posterior tibial-femoral component, which protects the anterior cruciate ligament (ACL) from anterior tibial-femoral shear. Therefore during closed kinetic chain activities, the quadriceps protects the ACL regardless of the activity of the hamstrings. Given that the quadriceps is much stronger than the hamstrings, has better leverage at low knee flexion angles, and a favorable vector with regard to the ACL during closed kinetic chain activities, and since most activities of daily living, sports, and non-contact ACL injuries occur with the foot on the ground, then it can be concluded that the quadriceps is the primary ACL protagonist. My findings have the following implications: (1) weak quadriceps are a risk factor for non-contact ACL injuries, (2) strong quadriceps are important for ACL injury prevention and rehabilitation, and (3) preservation of quadriceps strength is an important surgical goal.
Adult↗
Prolonged C-fibre mediated facilitation of the flexion reflex in the rat is not due to changes in afferent terminal or motoneurone excitability.
A standard suprathreshold mechanical stimulus applied to the hindpaw of decerebrate-spinal rats produces a discharge in hamstring flexor alpha-motoneurones which is stable for hours, provided no tissue injury is produced. Tissue injury results, however, in a decrease of threshold and an increase in the responsiveness of the reflex. This reflex hypersensitivity can be mimicked by brief (20 s) low frequency (1 Hz) conditioning stimuli to muscle or cutaneous nerves, if C-fibres are recruited. The prolonged post-conditioning facilitation of the flexion reflex by C-afferent volleys is now shown to be independent of changes in the excitability of the test afferent terminals in the dorsal horn and of the motoneurones. The hypersensitivity is therefore due to changes in the interneurones that link cutaneous nociceptive afferents with flexor motoneurones.
Animals↗
A pilot randomised controlled trial of eccentric exercise to prevent hamstring injuries in community-level Australian Football.
Hamstring injuries are the most common injury sustained by Australian Football players. Eccentric training has been proposed as a potential preventative strategy. This pilot randomised controlled trial (RCT) evaluated the effectiveness of a pre-season eccentric training program for preventing hamstring injuries at the community level of Australian Football. Seven amateur clubs (n=220 players) were recruited. Players were randomised within clubs to the intervention (eccentric exercise) or control (stretching) groups and randomisation was stratified according to previous history of hamstring injury. Five exercise sessions were completed over a 12-week period, three during the pre-season and two during the first 6 weeks of the season. Compliance was recorded and players were monitored for the season to collect injury and participation data. There was no difference between the control (n=106) or intervention (n=114) groups with respect to baseline characteristics. Only 46.8% of all players completed at least two program sessions. Compliance was poorest for the intervention group. Intention-to-treat analysis suggested that players in the intervention group were not at reduced risk of hamstring injury (RR 1.2, 95% CI: 0.5, 2.8). When only control and intervention group players who participated in at least the first two sessions were analysed, 4.0% of intervention and 13.2% of control group players sustained a hamstring injury (RR 0.3, 95% CI: 0.1, 1.4; p=0.098). The findings suggest that a simple program of eccentric exercise could reduce the incidence of hamstring injuries in Australian Football but widespread implementation of this program is not likely because of poor compliance.
Adolescent↗
A Three-Dimensional Musculoskeletal Model of the Human Knee Joint. Part 2: Analysis of Ligament Function.
A three-dimensional model of the knee is used to study ligament function during anterior-posterior (a-p) draw, axial rotation, and isometric contractions of the extensor and flexor muscles. The geometry of the model bones is based on cadaver data. The contacting surfaces of the femur and tibia are modeled as deformable; those of the femur and patella are assumed to be rigid. Twelve elastic elements are used to describe the geometry and mechanical properties of the cruciate ligaments, the collateral ligaments, and the posterior capsule. The model is actuated by thirteen musculotendinous units, each unit represented as a three-element muscle in series with tendon. The calculations show that the forces applied during a-p draw are substantially different from those applied by the muscles during activity. Principles of knee-ligament function based on the results of in vitro experiments may therefore be overstated. Knee-ligament forces during straight a-p draw are determined solely by the changing geometry of the ligaments relative to the bones: ACL force decreases with increasing flexion during anterior draw because the angle between the ACL and the tibial plateau decreases as knee flexion increases; PCL force increases with increasing flexion during posterior draw because the angle between the PCL and the tibial plateau increases. The pattern of ligament loading during activity is governed by the geometry of the muscles spanning the knee: the resultant force in the ACL during isometric knee extension is determined mainly by the changing orientation of the patellar tendon relative to the tibia in the sagittal plane; the resultant force in the PCL during isometric knee flexion is dominated by the angle at which the hamstrings meet the tibia in the sagittal plane.
Journal Article↗
The physiology of mechanoreceptors in the anterior cruciate ligament. An experimental study in decerebrate-spinalised animals.
The physiological role of mechanoreceptors in the anterior cruciate ligament (ACL) was studied in unanaesthetised decerebrate-spinalised cats and dogs. Tonic activity in the quadriceps and the hamstring increased in response to physiological loading of the ACL. Evoked potentials in the posterior articular nerve (PAN) were elicited by electrical stimulation of the surface of the ligament. ACL loading also induced significant discharges from the PAN. The results suggest that ACL loading has an excitatory effect on the thigh muscles through a multimotor neurone output, and that the PAN is one of the afferent routes from the mechanoreceptors of the ACL. The ACL-muscle reflex may therefore play a physiological role in maintaining knee kinematics.
Animals↗
Rationale for training programs to reduce anterior cruciate ligament injuries in Australian football.
This commentary presents the rationale for training programs to reduce the incidence of knee injuries. Our studies have revealed that the external knee loading patterns during sidestep cutting are what put the anterior cruciate ligament at greatest risk for injury. Compared to running, sidestep cutting involves similar levels of knee flexion loading but increased loading in varus-valgus and internal rotation of the knee, and these external loads need to be stabilized or supported by the internal structures of the knee. People use a generalized hamstrings and quadriceps co-contraction to stabilize these external loads, thereby reducing ligament loading. It is proposed that perturbation of the joint receptors reinforces the use of selective hamstrings and quadriceps co-contraction patterns superimposed on a generalized co-contraction pattern. This is not by immediate ligamento-muscular protective reflex, which is too slow to provide any adequate support, but by enhanced proprioceptive information that may be used in learning. In contrast, the immediate effect of muscle stretch reflexes would be to reduce co-contraction, a possibly negative outcome for joint stabilization. The effects of different types of training on the control of joint stability are examined. It is proposed that resistance training may not be appropriate because it enhances muscle stretch reflexes, which may reduce co-contraction, and produces no reductions in voluntary activation times and time to peak torque. However, stability and balance training is thought to suppress muscle stretch reflexes and, in turn, enhance co-contraction. Also, stability and balance training that stimulates the knee joint ligament and capsular receptors may reinforce co-contraction patterns to facilitate greater improvements in joint stabilization. Stability and balance training and plyometric training produce reductions in voluntary activation times and times to peak torque, which may decrease muscle response times so players are more able to perform rapid and unexpected sports maneuvers. Training programs that emphasize these neuromuscular mechanisms may enhance protection of the anterior cruciate ligament and reduce the incidence of injury.
Anterior Cruciate Ligament↗