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Effect of sodium bentonite or hydrated sodium calcium aluminosilicate on growth performance and tibia mineral concentrations in broiler chicks fed nutrient-deficient diets.

An experiment was conducted to determine whether sodium bentonite (NaB) or hydrated sodium calcium aluminosilicate (HSCA) would affect growth performance and tibia mineral concentrations in chicks fed nutrient-deficient diets. Two identical trials were conducted; each using 240 5- to 19-d-old broiler chicks (4 replicates of 5 chicks each) in a completely random design. A factorial arrangement of treatments consisted of four types of nutrient deficiencies [nutritionally complete basal (C), macromineral-deficient (-MM), trace mineral- and vitamin-deficient (-TMV), and crude protein-deficient (-CP)], and three types of additive (none, .5% NaB, and .5% HSCA). The -MM and -TMV diets reduced (P < .01), gain, feed intake, and gain:feed. The -CP diet decreased (P < .01) gain and gain:feed but did not affect (P > .10) feed intake. Sodium bentonite increased feed intake (P < .01) of all diets; resulting in an increase in gain (P < .09). Sodium bentonite increased gain:feed in chicks fed the -MM diet but did not affect gain:feed in chicks fed the C, -TMV, or -CP diets (NaBx-MM interaction, P < .02). The -MM and -TMV diets decreased (P < .01) tibia ash, but the -CP diet increased (P < .01) tibia ash. The -MM diet decreased (P < .01) tibia Ca but increased (P < .01) tibia P. Neither NaB nor HSCA affected percentage of tibia ash, Ca, or P. Tibia Zn and Mn concentrations were increased (P < .01) by the -MM diet and decreased (P < .01) by the -TMV diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Silicates↗

[Tibia vara in adolescents. Apropos of 19 cases].

PURPOSE OF THE STUDY: Clinical, and radiological aspects and treatment of adolescent tibia have been studied in a review of 19 children native of the Caribbean. MATERIAL: 23 cases of adolescent tibia vara in 19 children have been collected (14 males and 5 females, aged from 9 to 14). METHODS: Clinical aspects (weight, lower limb axis), radiological signs (aspect of the physis, mechanical axis, epiphyseal slope) were studied pre and post-operatively. RESULTS: All the boys presented an important overweight. Pain was the first symptom, characterized by a progressive varus deformity on a leg which was previously straight. Radiological findings consisted in metaphyseal varus and widening of the medial part of the physis. Mechanical femoro-tibial axis varied from 10 degrees to 55 degrees varus, medial epiphyseal slope from 12 degrees to 30 degrees. Average mechanical femoral angle was 92 degrees and accounted for a mean femoral varus deformity of 4 degrees. 23 knees were operated, 4 after fusion of the whole physis. 10 lateral hemi-epiphysiodesis were performed with a mean correction of 4 degrees every year until fusion. In 3 cases a tibial osteotomy was made in a second time, at the end of growth. In 6 cases of late treated patients, an isolated tibial osteotomy of valgisation was performed. In 7 cases of important deformity before closure of the physis, tibial osteotomy was associated with lateral epiphysiodesis. In one case, a lateral closing wedge osteotomy was performed, associated to an elevation of the medial tibial plateau and a lateral hemi-epiphysiodesis. DISCUSSION: Histopathological examination of the physis showed similarities between adolescent tibia vara, infantile tibia vara and Slipped capital femoral epiphysis: the entire physeal plate was involved. Concerning pathogenesis of adolescent tibia vara, mechanical factors are predominant, with abnormal pressures across the medial part of the physis. CONCLUSION: Adolescent tibia vara occur in obese black children and can be considered as an epiphysiolysis of the upper end of the tibia.

Adolescent↗

[Testing of anisotropic modulus and fluid characteristic of Chinese femur and tibia].

The tension moduls and compression modulus of Chinese tibia and femur of male in three different directions, namely axial, circumferential and radial directions, were tested in our experiments. The measured compression moduli are 5.8 +/- 0.34, 3.4 +/- 0.17, 2.1 +/- 0.18 GPa respectively for femur, and 6.1 +/- 0.36, 3.5 +/- 0.17, 2.1 +/- 0.18 GPa respectively for tibia; the measured tension moduli are 15.6 +/- 1.21, 9.8 +/- 0.73, 5.4 +/- 0.52 GPa respectively for femur, and 16.7 +/- 1.09, 10.3 +/- 0.70, 5.6 +/- 0.49 GPa respectively for tibia. The tension and compression ultimate strengths of femur and tibia were tested, too. The measured compression ultimate strengths are 150 +/- 9.3, 111 +/- 6.5, 110 +/- 7.1 MPa respectively for femur, and 191 +/- 12.3, 140 +/- 6.3, 123 +/- 8.3 MPa respectively for tibia; the measured tension ultimate strengths are 115 +/- 9.6, 82 +/- 6.8, 78 +/- 7.3 MPa respectively for femur, and 143 +/- 8.7, 110 +/- 8.3, 97 +/- 6.4 MPa respectively for tibia. Furthermore, the stress-relaxation experiments were conducted. The relation between loading and time during the experiments were obtained by the method of curve fitting. They meet the logarithm function: F = A * B(log t); A is the initial load, and B is the fitting material parameter. For femur, B is equal to 0.985; for tibia, B is equal to 0.987.

Anisotropy↗

Relative growth between femur and tibia in the German cockroach, Blattella germanica.

Femur and tibia length of fore, mid, and hindleg, and head width were measured throughout larval stages up to the adult in both sexes. All the leg segments showed positive allometric growth against head width. Postero-anterior and disto-proximal growth gradients along the body and leg axes were detected. Total length of femur and tibia of foreleg in a particular instar was nearly equal to that of midleg in the preceding instar, and to that of hindleg in the instar before the preceding instar. Ratio of tibia length to femur length was high in hindleg, intermediate in midleg, and low in foreleg. The ratio increased as the stage advanced in mid and hindleg. Correlation coefficients between any two of the 12 leg segments, femur and tibia of both sides of the body, were calculated in every instar up to the adult stage. In all the three kinds of legs, the values between femur and femur, and tibia and tibia, of opposite side of the body were higher than those between femur and tibia of the same leg. It was also revealed that foreleg correlated more closely to midleg than to hindleg, and midleg, more closely to hindleg than to foreleg.

Animals↗

[Preliminary evaluation on bone mass of tibia by ultrasonic measurement].

The speed of ultrasound (SOS) in right middle tibia and bone mineral density (BMD) of left radius at the distal one-third were measured by ultrasonic measurement and single photoabsorptionmetry in 260 healthy individuals simultaneously. SOS of tibia was positively correlated with BMD of radius (r = 0.64). The peak bone mass of both measurements was at 33 to 36 years of age. Height was positively correlated with the SOS of tibia, while weight was positively correlated with SOS of female tibia, period of menopause negatively correlated with female's SOS of tibia. The concordance of SOS of tibia and BMD of radius in diagnosis of osteoporosis was 36.8%. The results suggest that ultrasonic measurement of tibia is an effective method of bone mass measurement.

Adolescent↗

Fracture threshold in the femur and tibia of people with spinal cord injury as determined by peripheral quantitative computed tomography.

OBJECTIVE: To determine bone traits of the femur and tibia with peripheral quantitative computed tomography (pQCT) that best distinguish between spinal cord injury (SCI) subjects with and without fractures. DESIGN: Cross-sectional study. SETTING: In- and outpatient paraplegic center in Switzerland. PARTICIPANTS: Ninety-nine motor complete SCI subjects (duration of paralysis, 2 mo-49 y), 21 of whom had sustained fractures of the femur or tibia. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects with SCI were questioned about the occurrence, location, and approximate date of fractures to their lower extremities. Trabecular and cortical bone mineral density (BMD), as well as bone geometric properties of distal epiphyses and midshafts of the femur and tibia, were measured by pQCT. RESULTS: Trabecular BMD of the femur and tibia distal epiphyses was found to distinguish best subjects with fractures from those without. Fractures occurred in subjects with trabecular BMD of less than 114 mg/cm 3 and less than 72 mg/cm 3 for the femoral and tibial distal epiphysis, respectively (corresponding to 46% and 29% of mean values of an able-bodied reference group). Approximately 50% of the subjects with chronic SCI (defined as time postinjury >5 y for femur data and >7 y for tibia data) had trabecular BMD values above the fracture threshold in the femur and about one third above the fracture threshold in the tibia. CONCLUSIONS: By using pQCT, it may be possible to identify subjects with SCI who are at risk of sustaining fractures of the femur and tibia through minor trauma.

Adult↗

Compartment pressures after submuscular fixation of proximal tibia fractures.

INTRODUCTION: Tibial fractures are known to be associated with elevated compartment pressures, which may potentially result in a compartment syndrome. The Tibial Less Invasive Stabilization System (LISS PLT) is an internal fixator device that is designed for fixation of proximal tibia fractures. The technique includes submuscular placement of the implant along the lateral border of the tibia. Such placement of the Tibia LISS into the anterior leg compartment could increase compartment pressures, and therefore increase the risk of compartment syndrome. The objective of this prospective study is to determine whether submuscular placement of a tibia LISS fixator increases compartment pressures and what is the incidence of compartment syndrome. MATERIALS AND METHODS: Twenty-eight consecutive proximal tibia fractures were fixed using the Tibia LISS (LISS PLT). Compartment pressures in all four leg compartments were measured pre- and postoperatively. Diastolic pressures were recorded and perfusion pressures calculated. RESULTS: There were no statistically significant differences between pre- and postoperative compartment pressures. One patient out of twenty-eight developed an impending compartment syndrome after placement of the LISS implant. CONCLUSIONS: Submuscular fixation of the tibia with the Less Invasive Stabilization System does not cause a significant rise in leg compartment pressures, nor is it associated with an increased incidence of compartment syndrome.

Bone Plates↗

Tibia fractures produced from the impact of a baseball bat.

Forty-seven patients presented during a 1-year period with fractures of the extremities produced by the impact of a baseball bat. This represented an increase of fourfold in fractures associated with baseball bat trauma as compared with the previous year. Those patients with tibia fractures were retrospectively reviewed in terms of associated soft-tissue injuries, fracture pattern, and fracture healing. Potential force generated and kinetic energy transferred when a baseball bat strikes the tibia were calculated mathematically to provide correlation with clinical observations. Tibia fractures produced by baseball bats represented 10% of all tibia fractures presenting from July 1990-July 1991. Of these 11 tibia fractures, 3 developed compartment syndrome, necessitating fasciotomy and subsequent skin grafting, and 1 developed osteomyelitis, which eventually resulted in amputation. One patient had superficial skin blistering that required a delay in definitive fracture care of 11 days and subsequent skin grafting. There was one nonunion and three delayed unions requiring additional operative intervention. This incidence of compartment syndrome (27%) is nine times higher than the overall incidence, at this institution, of compartment syndrome (3%) in tibia fractures produced by other mechanisms. The maximum potential kinetic energy produced during the impact of a baseball bat is 515 kg/m2/s2: 25% higher than that produced by a 9-mm bullet fired at a distance of 6 ft (407 kg/m2/s2). The potential force transmitted from a bat to the tibia at the time of collision is 8,000 lb, three times that of the bullet (626 lb).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

MR diagnosis of complete tears of the anterior cruciate ligament of the knee: importance of anterior subluxation of the tibia.

OBJECTIVE: The primary role of the anterior cruciate ligament is to resist anterior subluxation of the tibia. When the ligament is torn, the tibia is free to sublux anteriorly when the leg is pulled forward. In addition to visualizing the anterior cruciate ligament directly, MR imaging can show joint alignment. The purpose of this study was to test the efficacy of MR images of anterior subluxation of the tibia for diagnosing complete tears of the anterior cruciate ligament. MATERIALS AND METHODS: We evaluated the records of 120 consecutive patients who underwent MR imaging of the knee and subsequently had arthroscopy. Arthroscopy showed a complete tear of the anterior cruciate ligament in 21 patients, a partial tear in eight patients, and an intact anterior cruciate ligament in 91 patients. Two radiologists together reviewed the MR images, and interpretation of anterior cruciate ligament integrity was reached by consensus. The anterior cruciate ligament was categorized as intact, completely torn, or partially torn on the basis of conventional MR imaging criteria. The degree of anterior subluxation of the tibia was measured on a separate occasion in random order by a radiologist who used a sagittal section through the middle of the lateral femoral condyle. On the selected image, two vertical lines parallel to the left and right margins of the image frame were drawn tangent to the posterior cortical margins of the lateral femoral and tibial condyles. Anterior subluxation of the tibia was determined by the distance in millimeters between these two lines and measured with calipers by using the 5-cm scale on the images. Measurements were considered reliable only to one half of the smallest increment of this scale (i.e., 5 mm). Accordingly, tibial subluxation (x) was measured in 5-mm increments, with x < or = 0 mm designated grade 0, 0 mm < x < or = 5 mm designated grade 1, 5 mm < x < or = 10 mm designated grade 2, and so forth. RESULTS: Conventional MR imaging criteria had 90% sensitivity and 94% specificity for diagnosing complete tears of the anterior cruciate ligament. According to the receiver-operating-characteristic (ROC) curve, anterior subluxation of the tibia greater than 5 mm (grade 2 or greater) was considered to be the optimal threshold (sensitivity, 86%; specificity, 99%) for diagnosing complete tears of the anterior cruciate ligament. Notably, none of the six false-positive diagnoses of complete tears by conventional criteria (three partial tears and three intact ligaments at arthroscopy) were misdiagnosed when tibial subluxation was used as the diagnostic criterion. Subluxation greater than 5 mm can be falsely negative with chronic tears of the anterior cruciate ligament (n = 2) or when a displaced bucket-handle tear of the lateral meniscus blocks anterior subluxation of the tibia (n = 1). CONCLUSION: An anterior tibial subluxation greater than 5 mm (grade 2 or greater) is a simple objective measurement that serves as a helpful adjunctive sign in the diagnosis of complete tears of the anterior cruciate ligament. This sign also offers improved discrimination of complete from partial tears of the anterior cruciate ligament.

Adult↗

[Change in the procedure from external fixator to intramedullary nailing osteosynthesis of the femur and tibia].

Shaft fractures of femur and tibia can be treated successfully by intramedullary nailing. In recent years the use of interlocking nails widened the indication for nailing fractures of the proximal and distal bone and more difficult fractures. There are still limits in polytrauma patients, chain fractures with or without participation of joints and in fractures with severe soft tissue injury (open or closed). In these cases primary treatment with external fixation has proved worthwhile. The main problems and risks of primary nailing osteosynthesis occur in the early phase of treatment, whereas complications in external fixation are more likely to occur in later phases of treatment. In changing from external fixation to intramedullary nailing one can see the advantages of both methods. In the literature only small studies have been made mostly with patient groups below 50 in number. The change of method was rarely standardised and the time period between procedures was either late (more than 3 weeks) or arbitrary. The advantages and disadvantages as well as the risk in changing methods are controversial. In a 2-year prospective study from August 1989 to July 1991, patients with II and III degree open and closed femur and tibia fractures as well as trauma patients with fractures were initially treated by external fixation. A change of method from external fixation to intramedullary nailing was performed at the earliest possible time under exact criteria. 61 femur and 106 tibia fractures were accordingly treated and followed. In comparison to early studies there were no differences in bone healing or in functional results. The infection rate in tibia fractures was 1.9% (2 of 106); no infection was seen in femur fractures. The contamination rate at the time of method change was substantially higher at 14%. The difference between contamination and infection rate can be explained by experience in the technique of nailing, considering biological aspects (no or little reaming), the standardized change of method and the prophylactic use of antibiotics. In a follow-up of additional 37 femur and 58 tibia fractures that were treated accordingly, a total infection rate of 1.9% was achieved (2% in femur fractures [n = 98], 1.8% in tibia fractures [n = 164], 1.9% total [n = 262]). In femur and tibia fractures with open or closed soft tissue damage and in multiple trauma patients the treatment with initial stabilisation by external fixation and secondary change to intramedullary nailing can be recommended under certain conditions.

Adolescent↗

A pilot evaluation of tibia lead concentrations in Taiwan.

BACKGROUND: The aims of this study were to examine some of the factors that influence tibia lead concentrations, tibia lead x-ray fluorescence measurement uncertainty and blood lead concentrations, and to compare tibia lead concentrations in Taiwanese lead workers to those observed in lead workers from other countries. METHODS: A pilot evaluation of 43 adult lead workers who underwent measurements of tibia lead and blood lead concentrations. RESULTS: Mean and maximum tibia lead concentrations were 54 microg of Pb per g of bone mineral(microg/g) and 193 microg/g, respectively. Mean and maximum blood lead concentrations were 44 microg/dl and 92 microg/dl, respectively. CONCLUSION: Past occupational control of lead exposure in Taiwan, ROC, did not prevent these workers from accumulating tibia lead concentrations greater than those in similar workers elsewhere in the world.

Adolescent↗

Donor site morbidity after harvesting of proximal tibia bone.

BACKGROUND: Bone-grafting procedures are common in head and neck surgery. Donor site morbidity is an important factor in deciding the site for harvest of cancellous bone. The tibia has been recommended as a harvest site. Use of the proximal tibia as a donor site is associated with few complications. Our present study used proximal tibia bone grafts to reconstruct maxillofacial defects and augment bone volume for implantation. METHODS: A retrospective study was undertaken to analyze 40 proximal tibia bone grafts in maxillofacial reconstruction. Minimal follow-up was 6 months. RESULTS: There were no major complications during the follow-up period. Early minor complications (15%) included temporary sensory loss and ecchymosis. Late minor complication (2.5%) was gait disturbance for 2 months. Long-term minor complication (2.5%) was an unsightly scar. CONCLUSION: The procedure for proximal tibia bone graft is easy, has less operative risk, and results in a lower postoperative morbidity rate. Based on our findings, we believe the proximal tibia offers a reliable site for harvest of sufficient quantities of good-quality cancellous bone.

Adult↗

Volumetric model determination of the tibia based on 2D radiographs using a 2D/3D database.

We present a new concept with mathematical background for the construction of a three-dimensional (3D) volumetric model of the human tibia based on two conventional orthogonal two-dimensional (2D) radiographic images. This approach is supported by a computer database containing a collection of 80 2D/3D image data sets of individual cadaveric tibiae. For each of these tibiae, the database contains digitized 2D orthogonal radiographic images in both anterior and lateral views, and the corresponding 3D CT data obtained by computerized tomography. To obtain a 3D model of a tibia for a given patient, shape matching is performed. The computer finds the most similar tibia to the patient's tibia among the 2D radiographic images in the database by applying a matching process. To improve accuracy, a 2D image warping procedure can be applied on the slices of the selected bone prior to 3D reconstruction. The warping process is controlled by the contour data of the two orthogonal views. We found that the 3D model thus achieved was useful for virtual preoperative planning and for simulation of the internal fixation of long bones.

Cadaver↗

Muscle contraction increases the in vivo structural strength to the same degree in osteopenic and normal rat tibiae.

The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%). The control rats were sham operated and fed a diet containing 1.1% calcium. After 7 weeks the right lower leg of all animals were fractured in three-point ventral cantilever bending during muscle contraction induced by electrical stimulation of the ischiatic nerve. The left tibiae were resected and fractured as each animal's control. During muscle contraction in vivo, the ultimate bending moment, energy absorption, bending stiffness, and deflection were significantly lower in the osteopenic than in the sham-operated animals. However, the increase in mechanical parameters due to muscle contraction comparing the in vivo and resected tibiae in each animal were equally high in the osteopenic and sham-operated animals. Ultimate bending moment in the resected tibiae was 10% higher in the sham-operated animals compared with the ovariectomized, proving mechanically weaker tibiae in the osteopenic rats. In accordance with this, the medullary area of the osteopenic rats was 46% larger in the distal tibial diaphysis, and the ultimate stress the tibiae could withstand was 15% lower in the osteopenic compared with the sham-operated rats. The trabecular bone volume in the distal tibial metaphysis of the osteopenic rats was reduced by 70% compared with the sham operated. This study shows that muscle protection against fracture can be substantial in osteopenic tibia and that it is of the same magnitude as in rats with normal bone mass.

Animals↗

Limb lengthening by low rate epiphyseal distraction. An experimental study in the caprine tibia.

Low-rate epiphyseal distraction of the left proximal tibia using a modified bilateral Hoffmann external fixation device, was accomplished in 14 goats (age 6-7 months). Daily distraction at a rate of 0.5 mm was continued for 5.5 weeks. Epiphysiolysis occurred after 5-9 days. After distraction had been discontinued, the external device was left in situ for fixation for 4 weeks. The animals in group 1 (n = 6), group 2 (n = 3), and group 3 (n = 5) were killed at 4, 16, and 32 weeks, respectively, from the end of the distraction period. The proximal growth plate of the elongated tibia appeared radiolucent at the conclusion of the study but was less distinct and reduced in height as compared with the control leg. The gained length at the end of the distraction period was on the average 2.2 cm (11.9%). This gain in length was reduced with further growth. In group 3, the final gain in length was reduced to half. A reduced cortical thickness of the bone within the area subjected to distractional force was observed. This finding is attributable to stress protection. An interesting observation comparing control and operated tibia was an increase of the cross-sectional diameter of the elongated bone. Both tibiae of all animals were tested mechanically. The torsional strength of the elongated tibiae as compared with controls was on the average 29% in group 1, 79% in group 2, and 95% in group 3. We conclude that leg lengthening by low-rate epiphyseal distraction in the proximal tibia is a justifiable alternative to other lengthening procedures in individuals approaching adolescence. In juveniles, lengthening by epiphyseal distraction may result in reduction in the longitudinal growth.

Animals↗

Blood flow changes in the tibia during external loading.

The influence of external load on the blood flow of the rabbit tibia was assessed by laser Doppler flowmetry (LDF). Blood flow readings were obtained from three adolescent and three adult female New Zealand White rabbits whose tibiae previously had been pinned with modified orthopaedic pins. Readings were obtained from the exposed mid-shaft of the tibia of each hind leg before, during, and after loading. The loading was either static or sinusoidal intermittent. The LDF resulted in a reading from the tibia which was consistent with the recordings of blood flow; the traces were similar to the pulsatile nature of pulse pressure recordings. After loading of the tibia, in both the adolescent and adult rabbits the effects were an increase in blood flow, as measured with LDF, on the tensile aspect, and a decrease in flow on the compressive side. These changes were statistically significant (p < 0.01) as measured by a Student t test. This change in flow reached a plateau with change in strain. Furthermore, the changes in flow produced by loading continued as long as the load was applied. A response similar to reactive hyperaemia occurred on the compressive aspect of the tibia; there was an increase of blood flow above the resting level after removal of the static load. The effect of a sinusoidal intermittent load was less than that of a static load, and the differences in flow between tensile and compressive aspects was not significant. The changes induced offer further insight into factors controlling bone remodelling.

Animals↗

Anterior tibial artery and its actual projection on the lateral aspect of the tibia: a cadaveric study.

The anterior tibial artery (ATA) is at risk of injury during high tibial osteotomy, Ilizarov wire placement, pin placement in external fixation, or proximal locking screw insertion, as the artery is not visualized intraoperatively. The ATA is anchored to the oval foramen of the interosseous membrane on the proximal tibia by the deep fascia and recurrent genicular vascular branches. Segment 1 (from the bifurcation of the popliteal artery to the level of the interosseous foramen) and the proximal part of segment 2 (from the interosseous foramen to the level where the artery crosses the anterior border of the tibia) may be damaged when pin, wire or screw placement is directed posterolaterally at that level. Distally, a straight mediolateral pin or Ilizarov wires may lacerate the artery. Segment 2 of the ATA descends against the interosseous membrane in its proximal part, which is projected on the posterior third of the tibia relative to the sagittal plane; in its middle part, it runs close to the lateral cortex of the tibia, it is projected on the middle third of the tibia; in its distal part it runs gradually towards the anterior third of the tibia and contacts with the anterior third of the tibial cortical surface. This information may help reduce risk of injury to the ATA during high tibial osteotomy, external fixation and pin placement or insertion of locking screws.

Bone Nails↗

Differentiation of hamstring short latency versus medium latency responses after tibia translation.

After injuries to the anterior cruciate ligament (ACL) a functional instability is frequently observed which has been attributed to a disturbed sensorimotor function. In light of the clinical importance of ACL injuries and the resulting functional instability, it is of enormous clinical interest to elucidate the role of sensorimotor pathways that involve the ACL. In animals and humans a direct reflex pathway between the ACL and the hamstrings has been shown. The onset latencies of responses reported after ventral tibia translation were around 40-50 ms (range 17.9-65) and were regarded as medium latency responses (MLR). However, ventral tibia translation should also induce a stretch of the hamstring muscles and evoke a short latency response (SLR). Before any muscle response after ventral tibia translation can be ascribed to anatomical structures, it is crucial to analyze the obtained muscle responses carefully. The aim of the present study was the development of an algorithm to differentiate SLR and MLR responses after ventral tibia translation. In ten healthy subjects reflex responses of the hamstrings after anterior tibia translation and after tendon taps on the biceps femoris tendon were evaluated. To investigate the influence of skin afferents, control experiments were performed after lidocain injection of the dorsal calf. The mean onset latency of the tendon jerk reflex was 21.9 +/- 3.1 ms (range 17.3 - 28.7 ms). Both SLR responses (mean onset latency: 20.3 +/- 3.5 ms; range 15.4 - 25.8) and MLR responses (mean onset latency: 38.9 +/- 4.2 ms; range 32.9 - 46.7) were obtained in all subjects. Skin afferents from the calf do not play a major role. The development of an evaluation algorithm is presented that allows a safe differentiation between these partly superimposed SLR and MLR components. It is demonstrated that by measuring the first part of the SLR from the onset to the first peak the end of the SLR can be predicted and that the onset latency of the MLR component can be assessed reliably. Possible reasons are discussed why previous studies only reported responses at MLR latencies. The fact that both SLR and MLR components can be observed after anterior tibia translation underlines the necessity to differentiate the responses before they can be ascribed to any anatomical structures. As a basis for future work the algorithm presented may become a useful tool to differentiate which afferent pathways play a role in initiating hamstring activity.

Adult↗