Trunk,pelvis and lower limb coordination between anticipated and unanticipated sidestep cutting in females

BackgroundEmerging research has suggested a plausible relationship may exist between lower limb coordination and musculoskeletal injury. A small number of studies have investigated the link between coordination and anterior cruciate ligament (ACL) injury during sidestep cutting. While prior work has shown unanticipated sidestep cutting to exhibit a more ‘at risk’ kinematic profile compared to anticipated tasks, a detailed understanding of the coordination between multiple joints and how they differ during unanticipated actions is lacking, particularly in females.Research questionThe purpose of this study was to observe the difference in trunk, pelvis and lower limb coordination and coordination variability during a dynamic, sidestep cutting task under anticipated and unanticipated conditions in a healthy female cohort.MethodsThree-dimensional motion analysis data were recorded during anticipated and unanticipated sidestep cutting for nineteen healthy female participants (age, 24 ± 3yrs; height, 164 ± 5 cm; and weight, 58 ± 6 kg). Vector coding methodology was used to calculate coordination and coordination variability values and statistical parametric and non-parametric mapping was used to comprehensively determine differences between anticipated and unanticipated conditions.ResultsDifferences were observed between anticipated and unanticipated conditions in the hip flexion – knee abduction angle (89 % of stance), hip rotation – knee abduction angle (55 % of stance), knee flexion – knee abduction angle (81–83 %, 86 % and 88–89 %) and knee flexion – ankle flexion angle (14–18 %) coupling angles. Differences in coupling angle variability were also observed with only one cluster of significance seen in hip abduction – knee abduction variability (27–30 % of stance).SignificanceHealthy females exhibit significant differences in lower limb coupling angles and coupling angle variability between anticipated and unanticipated sidestep cutting. Interventions aimed at reducing ACL injury risk may need to consider that anticipated and unanticipated sidestep cutting tasks present unique demands, and therefore should both be trained specifically.     

Assessing lower extremity coordination and coordination variability in individuals with anterior cruciate ligament reconstruction during walking

BackgroundDespite our knowledge of several biomechanical risk factors related to anterior cruciate ligament (ACL) injury, such as decreased knee flexion, increased knee abduction, and increased hip flexion, adduction and internal rotation during walking, jogging, and landing from a jump, the incidence of ACL tears remains high. Quantifying variability in the lower extremity provides a continuous measure of joint coordination and function that may elicit an additional aspect of ACL injury mechanisms. Research question: The aim of this study was to assess joint coordination patterns and variability in individuals following ACL reconstruction (ACLR).MethodsTwenty participants with unilateral ACLR and twenty uninjured participants matched by sex and body mass index (BMI) walked over-ground at self-selected speed. Two force plates embedded in the walking platform recorded ground reaction forces (GRF), and a motion capture system collected kinematic data. Vector coding was used to describe coordination patterns and measure coordination variability in hip-knee and knee-ankle coupled motion. Results: Individuals with ACLR had greater variability in hip-knee coordination compared to their healthy counterparts for both the reconstructed and contralateral limbs. The individuals with ACLR also exhibited altered coordination patterns, one of which was characterized by constrained hip motion.SignificanceThese results are evidence that differences in joint coordination exist between individuals with and without ACLR, even after the former are cleared to return to sport. This new insight into coordinative function after ACLR may be useful for improving rehabilitation strategies as well as identifying those at risk of injury during return to sport testing.     

Lower limb muscle activity and kinematics of an unanticipated cutting manoeuvre: a gender comparison

This investigation compared the amplitude and the timing of the muscle activity of the lower limb, as well as the three-dimensional kinematics of the hip, knee and ankle joints, of male and female elite soccer players performing an unanticipated cutting manoeuvre. These data were recorded for 15 female and 15 male participants for five successful cutting manoeuvres. For this manoeuvre to be performed in an unanticipated manner, the participants were instructed to execute one of three tasks, which were signalled to them with a target board composed of three different coloured lights. Female participants performed the cutting manoeuvre with greater lateral gastrocnemius activity in comparison with the male participants. It was also observed that they contracted their vastus lateralis to a greater extent than their vastus medialis, whereas the men adopted the opposite strategy. These neuromuscular control strategies adopted by the female athletes may elucidate the reasons for which women struck the ground with a more abducted knee during the cutting task. Given that this knee position places greater strain on the anterior cruciate ligament, a restoration of the medial/lateral activation balance of the lower limb muscles may reduce one’s risk of injury.     

关节镜下运用4股腘绳肌腱同期重建前后交叉韧带损伤

目的 关节镜下运用Intrafix和可吸收界面螺钉固定自体4股腘绳肌腱，同期重建前交叉韧带（anterior cruciate ligament，ACL）、后交叉韧带（posterior cruciate ligament，PCL），评估其疗效。方法 ACL、PCL同时损伤的患者16例，关节镜下以自体4股胭绳肌腱作为重建移植物，应用可吸收界面螺钉固定移植物股骨端，Intrafix钉鞘和可吸收锥形钉固定胫骨端，同期行ACL和PCL损伤重建术。7例行内侧副韧带修补，4例行外侧副韧带复合结构修复，2例行内外侧同时修复。所有患者按照国际膝关节评分委员会（International Knee Documentation Committee，IKDC）评分标准进行术前评估，均为D级。术前Lysholm评分为（36．5±3．7）分。结果 随访时间为12～18个月，平均14．6个月。终末随访时，IKDC总体评价：A级6例（38％），B级9例（56％），C级1例（6％），无D级患者。Lachman试验0～2mm8例；3～5mm6例；6～10mm2例（P〈0．05）。屈70°前后总位移0～2mm10例；3～5mm5例；6～10mm1例（P〈0．05）。屈70°后位移0～2mm12例；3～5mm4例（P〈0．05）。术后2个月Lysholm功能评分为（90．4±2．9）分，终末随访时为（93．4±3．5）分，与术前相比差异均有统计学意义（P〈0．05）。结论 关节镜下以自体4股胭绳肌腱作为移植物，应用可吸收界面螺钉、Intrafix钉鞘和可吸收锥形钉固定股骨胫骨端同期重建ACL和PCL损伤，有利于早期积极的功能康复，膝关节功能恢复满意。     

A meta-analysis of stability of autografts compared to allografts after anterior cruciate ligament reconstruction

Allografts have recently become increasingly popular for anterior cruciate ligament reconstruction (ACLR) in the United States even though many studies have shown high allograft failure rates (Gorschewsky et al. in Am J Sports Med 33:1202, 2005; Pritchard et al. in Am J Sports Med 23:593, 2005; Roberts et al. in Am J Sports Med 19:35, 2006) and no meta-analysis or systematic review of allograft clinical stability rates in comparison to autog rafts has previously been performed. We hypothesized that allografts would demonstrate overall lower objective stability rates compared to autografts. To test this hypothesis we performed a meta-analysis of autograft and allograft stability data. A pubmed literature search of all allograft series in humans published in English was performed. Articles were then bibliographically cross-referenced to identify additional studies. Series inclusion criteria were arthrometric follow-up data using at least 30 lb or maximum manual force, stratified presentation of stability data and minimum two-year follow-up. Twenty allograft series were thus selected and compared to a previously published data set of all BPTB and Hamstring (HS) autograft ACLR series using the same study inclusion criteria and analytic and statistical methodology. IKDC standards of 0–2 mm (normal) and >5 mm (abnormal) side-to-side differences were adopted to compare studies. Normal stability for all autografts was 72 versus 59% for all allografts (P < 0.01). Abnormal stability was 5% for all autografts versus 14% for all allografts (P < 0.01). Bone-patellar-tendon-bone (BPTB) autograft normal stability was 66% versus 57% for BPTB allografts (P < 0.01). Abnormal BPTB autograft stability was 6 versus 16% for BPTB allograft. Hamstring autograft normal or abnormal stability rates were 77% and 4% and were compared to soft tissue allografts as a group which were 64% and 12% (P < 0.01). This is the first meta-analysis comparing autograft to allograft stability in ACLR. Allografts had significantly lower normal stability rates than autografts. The allograft abnormal stability rate, which usually represents graft failure, was significantly higher than that of autografts: nearly three times greater. It would therefore appear that autografts are the graft of choice for routine ACLR with allografts better reserved for multiple ligament-injured knees where extra tissue may be required.     

韧带增强重建系统人工韧带重建前交叉韧带中期疗效分析

目的 评估韧带增强重建系统(ligament advancement reinforcement system,LARS)人工韧带重建前交叉韧带(anterior cruciate ligament,ACL)术后3-7年膝关节功能,了解LARS人工韧带在人体组织内的形态变化. 方法 选择符合标准的LARS人工韧带重建ACL患者57例(58膝),根据伤后至手术时间分为急、慢性损伤两组,对其进行多指标回顾性分析.其中对再手术患者(3例4膝)LARS人工韧带取材行组织学观察. 结果 LARS人工韧带重建ACL术后关节功能、膝关节运动水平明显高于术前(P＜0.01);两组间膝关节功能的主观评分及客观评估差异无统计学意义(P＞0.05);X线片及MRI显示平均1.5年骨隧道呈不同程度进行性扩大,关节稳定性与骨隧道扩大程度无明显相关性(P＞0.05),胫骨和股骨骨隧道扩大发生率差异无统计学意义(P＞0.05).组织学观察可见术后2年有规则排列纤维组织长入LARS人工韧带内,单束及成捆聚酯纤维间见广泛纤维连接. 结论 (1)LARS人工韧带重建ACL能够较好地恢复膝关节稳定性及功能.(2)骨隧道扩大现象存在,1.5年后趋于稳定,关节稳定性与术后骨隧道扩大程度无相关性.(3)急性损伤与慢性损伤术后的各项评估资料对比一致.(4)人体正常纤维组织结构能够规律地长入LARS人工材料.     

Effect of knee flexion on the in situ force distribution in the human anterior cruciate ligament

This study was conducted to evaluate the effect of applied load on the magnitude, direction, and point of tibial intersection of the in situ forces of the anteromedial (AM) and posterolateral (PL) bands of the human anterior cruciate ligament (ACL) at 30° and 90° of knee flexion. An Instron was used to apply a 100 N anterior shear force to 11 human cadaver knees, 6 at 30° of knee flexion and 5 at 90° of knee flexion. A Universal Force Sensor (UFS) recorded the resultant 6 degree-of freedom (DOF) forces/moments. Each specimen then underwent serial removal of the AM and PL bands. With the knee limited to 1 DOF (anteroposterior), tests were performed before and after each structure was removed. Because the path was identical in each test, the principle of superposition was applied. Thus, the difference between the resultant forces could be attributed to the force carried by the structure just removed. The magnitudes of force in the ACL at 30° and 90° of knee flexion were 114.1±7.4 N and 90.8±8.3 N, respectively (P<0.05). At 30°, the AM and PL bundles carried 95% and 4% of the total ACL force, respectively. At 90°, the AM and PL bands carried 85% and 13%, respectively (P<0.05). The direction of the in situ force in the whole ACL as well as its two bands correlated with the anatomic orientation of the ligament. The resultant total ACL force intersected the tibial plateau at the posterolateral aspect of the AM band's insertion at 30° of knee flexion, while at 90°, the force intersection moved posteriorly to the AM/PL border. This research provides new insight into the fundamental force relationships of the ACL and its bundles. In response to an anterior tibial shear force, the AM band of the ACL was the predominant load carrier at both 30° and 90° of knee flexion. However, contrary to carlier reports, the in situ force carried in the PL band increased as knee flexion increased. Further, the tibial intersection of the resultant ACL force moved laterally with knee flexion. These findings confirm the dynamic structure of the ACL that in itself has no isometricity and may also indicate that there is no ideal location in which to position a replacement graft. The use of this methodology with more physiologically unconstrained motion should lead to more definitive clinical conclusions.     

模拟重力下前交叉韧带的解剖运动学研究

目的研究模拟重力下前交叉韧带(ACL)的解剖运动学变化。方法本组21个尸体膝关节,比较在膝关节受模拟重力下,ACL前内侧束与后外侧束位移变化的差异;比较膝关节高度屈曲时韧带的位移变化。结果前内侧束最大位移为1.58mm,后外侧束为1.40mm。两束韧带的位移变化差异有统计学意义(P<0.05)。高度屈曲每增加10°,两束韧带的拉长都具有统计学意义(P<0.05)。结论膝关节受模拟重力时,ACL两束韧带起着不同的作用,高度屈曲受重力时韧带的变形显著增大。     

Bilateral changes in knee joint laxity during the first year after non-surgically treated anterior cruciate ligament injury

ObjectivesAnalyse changes in knee laxity between 3, 6, 12 and 24 months after non-surgically treated ACL injury and to analyse associations between knee laxity and knee function, self-reported knee stability, ACL-Return to Sport after Injury (ACL-RSI), fear and confidence at different timepoints during recovery.DesignProspective cohort study.Participants125 patients (67 males, mean age 25.0 ± 7.0 years) with acute ACL injury.Main outcomeLaxity was measured using KT-1000 arthrometer. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). Confidence and fear were assessed with questions from the ACL-RSI scale. Subjectively knee stability was assessed using SANE.ResultsKnee laxity increased bilaterally from 3 to 12 months, and in the non-involved knee from 3 to 24 months (p˂0.05), although mean change was below 1 mm. Side-to-side difference in knee laxity was correlated with IKDC-SKF (r = −0.283) and knee stability in rehabilitation/sport activities (r = −0.315) at 6 months, but not with confidence/fear.ConclusionKnee laxity increased bilaterally during the first year after non-surgically treated ACL injury, though, the mean change in knee laxity was below 1 mm and the clinical significance is unknown. Knee laxity was weakly associated with knee function and perceived knee stability.Level of evidenceLevel IITrial registrationNCT02931084     

前交叉韧带起止点X线下定位的研究

目的研究X线下前交叉韧带(anterior cruciate ligament,ACL)起止点印迹在股骨髁及胫骨平台上的定位,为术中重建ACL制备骨隧道时提供参考依据。方法采集12例正常国人膝关节标本,制作标本后分别在股骨髁及胫骨平台将ACL起止点边缘用金属丝标记,标记后摄标准的正侧位膝关节标本x线片,使用X-Caliper测量仪在CR片上精确测量ACL股骨髁和胫骨平台止点的几何中心与CR片骨性标记之间的距离。结果ACL股骨侧止点中心在股骨干力学轴与其平行线之间(65．3±1．1)%处,在Blumensaat线及其平行线之间(78．1±1．0)%处。胫骨侧止点中心在正位片上位于胫骨平台(47．1±2．6)%处,在侧位片位于(43．9±1．7)%处。结论股骨干力学轴和Blumensaat线及与其平行的股骨髁切线结合更方便定位ACL股骨侧标记；X线下胫骨平台定位更为准确。     

Review on tension in the natural and reconstructed anterior cruciate ligament

This article reviews the methodology and results of published studies concerned with tension in the natural and reconstructed anterior cruciate ligament (ACL). This also includes studies of fiber length changes with knee motion and the relationships between graft tunnel placements and isometricity. Little work has been done in vivo: in humans, length changes of the anterior ACL fibers have been measured at operation, while animal longitudinal studies have been few and have given conflicting results. Work in vitro has used many methods to study ACL tension directly or indirectly, via length changes in fibers, but many authors have reported variable results, caused partly by inter-specimen differences and lack of control of forces or kinematics. It seems likely that different grafts require different peroperative tensions to restore normal stability when measured immediately after application at one knee position. But graft placement and the angle at which tensioning is performed also matter. Overtensioning constrains knees under load cycling. Similarly, it is difficult to measure and therefore also to decide how tension should be distributed between an ACL graft and and augmentation to the graft. It was concluded that the published studies provide many guidelines for the effects of different graft placements or tensioning protocols but, overall, there is little firm evidence on which to recommend any particular ACL reconstruction protocol.     

Study on three-dimensional kinematics and electromyography of ACL deficient knee participants wearing a functional knee brace during running

This investigation examined the muscular activity and 3D knee joint kinematic changes of anterior cruciate ligament-deficient (ACLD) participants in the involved leg under bracing condition during running. Different adaptation strategies have been found between patients who can cope with the injury and patients who cannot. One of the expected changes can be the muscle activation characteristic of the injured knee during strenuous activity with and without a functional knee brace. Three-dimensional kinematic and electromyographical (EMG) data were collected from 11 participants for 10 consecutive gait cycles during running on a treadmill under both braced and unbraced conditions. Participants were administered the “Knee Outcome Survey Activities of Daily Living Scale” to distinguish functional and non-functional candidates. No significant differences on 3D kinematics and EMG data were noted between functional and non-functional participants, thus data analysis focused on comparisons of bracing conditions for one combined group. Bracing significantly reduced total range of motion in the frontal and transverse planes (P<0.05). Muscle activity at heel-strike showed a consistent trend to increase for the hamstrings and decrease for the quadriceps under the braced condition when compared to the unbraced condition. Our findings indicate that bracing the ACLD knee alters the kinematics of the injured leg while running. Tendencies toward reductions in quadriceps and increases in hamstrings activity at heel-strike indicate that bracing might have resulted in added stability of the injured knee. The adaptations to bracing found in this preliminary study further support the potential mechanical and proprioceptive contributions of the functional knee brace to protect the ACLD knee.     

Does peri-operative pregnancy alter the outcome of anterior cruciate ligament reconstruction? A report of four cases

Transient laxity in association with pregnancy of the native anterior cruciate ligament has been previously documented. This phenomenon has only been previously reported in one case of ACL reconstruction, but it has been recommended that patients that become pregnant soon after surgery should be closely observed. We report three cases of pregnancy in relation to primary ACL reconstruction with no obvious adverse outcomes observed on objective assessments. We also report one case of revision ACL reconstruction during pregnancy with a good clinical outcome. We suggest that any hormonal effects on ACL reconstruction during pregnancy, if they do occur, are likely to be very transient and of doubtful clinical impact. In addition, we feel that pregnancy should not be regarded as an orthopaedic contraindication to ACL reconstruction surgery.     

Alterations in medial-lateral postural control after anterior cruciate ligament reconstruction during stair use

BackgroundDynamic postural control during everyday tasks is poorly understood in people following anterior cruciate ligament reconstruction (ACLR). Understanding dynamic postural control can provide insight into potentially modifiable impairments in people following ACLR who are at increased risk for second ACL injury and/or knee osteoarthritis.Research questionDetermine whether measures indicative of dynamic postural control differ between individuals with and without ACLR during stair ascent and descent. Methods: Seventeen individuals with ACLR (>1 yr post-surgery) and 16 age and sex-matched healthy controls participated. Centre of pressure (COP) measures included: i) COP excursion, ii) COP velocity, and iii) dynamic time-toboundary (TTB). Mixed linear models were used to compare COP measures for the ACLR leg, non-ACLR leg, and healthy controls during stair ascent and stair descent.ResultsThere were no statistically significant differences observed during stair ascent (all p > 0.05). Several statistical differences were found during stair descent for individual with ACLR, but not between those with ACLR and healthy controls. The ACLR leg had higher medial-lateral COP excursion (mean difference 1.06 cm, [95 %CI 0.08–2.06 cm], p = 0.036; effect size = 0.38) compared to the non-ACLR leg during stair descent. In addition, the ACLR leg had a lower medial-lateral TTB (mean difference −13 ms [95 %CI −38 to 2 ms], p = 0.005; effect size = 0.49) and medial-lateral TTB normalized to stance time (mean difference −5.8 % [95 %CI −10.3 to 1.3 %], p = 0.012; effect size = 0.80) compared to the non-ACLR leg during stair descent. No statistical differences were observed for anterior-posterior measures during stair descent (all p > 0.05). Significance: Taken together, findings indicate that there are small to large differences in medial-lateral postural control in the ACLR leg compared to the non-ACLR leg during stair descent. Further work is required to understand clinical implication of these novel observations.     

Arthroscopic-assisted anterior cruciate ligament reconstruction with the central third patellar tendon A 5–8-year follow-up

We reviewed 89 arthroscopically assisted patellar tendon anterior cruciate ligament (ACL) reconstructions for chronic isolated injuries with an average follow-up of 7 years (range 5.4 to 8.6 years). Pain was present in 7 knees (8%). Giving-way symptoms were reported by 7 patients (8%). A KT-2000 side-to-side difference over 5 mm at 30 lbs was recorded in 12 cases (16%). The pivot shift was glide in 17 cases (19%) and clunk in 10 (11%). A 3°– 5° extension loss compared with the normal side was present in 20 knees (22%) and 6°–10° in 4 knees (4%). The intra-articular exit of the femoral tunnel was misplaced in the anterior 50% of the condyles along the roof of the notch in 10% of the knees. This positioning significantly (P = 0.003) increased the frequency of graft failure (62.5%) compared with the cases with a more posterior placement (graft failure 12%). An anterior position of the intra-articular exit of the tibial tunnel (in the anterior 15% of the sagittal width of the tibia) significantly (P = 0.01) increased the frequency of extension loss > 5°. Medial meniscectomy was associated with a 35% incidence of narrowing of the medial joint space, which was significantly higher compared with knees with normal menisci (9%; P = 0.04) or with medial meniscal repair (7%; P = 0.05). In conclusion this study showed satisfactory anterior stability (KT-2000 side-to-side difference up to 5 mm and pivot absent or glide) in 83% of the knees. This percentage increases to 88% in the knees with a correct posterior and proximal femoral tunnel placement. Accuracy in tunnel positioning is essential for the success of ACL surgery. Meniscal repair was effective in decreasing joint space narrowing and should be attempted when possible. Received: 15 November 1996 Accepted: 17 March 1997     

Dynamic joint loading following hamstring and patellar tendon anterior cruciate ligament reconstruction

This study compared lower limb dynamic joint loading after hamstring (HS) and patellar tendon (PT) anterior cruciate ligament (ACL) reconstruction. A three-dimensional motion analysis and force plate system were used to determine sagittal plane kinematics and kinetics in 20 subjects who had undergone ACL reconstruction (10 HS, 10 PT) whilst they performed both horizontal and vertical hopping tasks. Results for both activities showed significantly smaller knee flexion angles and external flexion moments in the operated than the non-operated limbs in PT subjects but no difference between limbs in HS subjects. There was no difference in the summated moment (hip plus knee plus ankle) between limbs for either graft type. The peak vertical ground reaction force was greater in the operated than the non-operated limb in PT subjects during the horizontal hop. These data show functional knee kinematic and kinetic differences between the two graft types that point to an earlier or better functional recovery in patients undergoing ACL reconstruction with HS graft than PT graft.     

A comparison of kinematic demands placed on the knee and hip during two ACL return-to-sport screening maneuvers and an agility test

ObjectivesThis study's purpose was to compare the kinematic demands placed on the knee and the hip during various biomechanical tests.DesignRetrospective cross-sectional design.SettingA university research laboratory.ParticipantsThe study sample consisted of 70 NCAA Division I female athletes.Main outcome measuresDuring the performance of three test maneuvers, a drop vertical jump (DVJ), single leg cross over hop (COH) and modified T-test (AT), the hip and knee joint angles at maximum knee valgus were obtained from marker displacement data collected using a 20-camera motion analysis system. A linear mixed model was used to compare the effect of test on joint angle.ResultsA significant difference (p < 0.001) in the frontal and sagittal plane position of the knee and hip was noted between the DVJ, COH, and AT tests at maximum knee valgus.ConclusionsThe DVJ, COH, and AT maneuvers do not appear to place the same kinematic stress on the knee, supporting the need for the development of return to sport tests that mimic on field demands.     

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.     

磁共振斜冠状位扫描对正常膝关节前交叉韧带的显示作用

目的 探讨磁共振斜冠状位扫描对膝关节前交叉韧带的显示价值.方法 对60例正常膝关节行常规扫描,包括斜矢状位、冠状位、横断位.所有病例均行在斜矢状位图像基础上平行于前交叉韧带FSE序列斜冠状位薄层无间隔质子密度加权扫描,分析斜冠状、斜矢状、冠状及横断位对前交叉韧带的显示情况.结果 斜冠状可清楚全程显示前交叉韧带于一幅图片上,显示率为100％(60/60),斜矢状位显示率为86.7％(52/60),而横断及冠状位则分段显示前交叉韧带,即不能在一幅图中完整显示前交叉韧带.结论 斜冠状位扫描符合前交叉韧带解剖走向,可明显提高前交叉韧带的完整显示率,有利于其损伤后评价.