Relationships between Quadriceps:Hamstring Strength Ratio and Lower Extremity Injuries in Netball Players

Background: Netball is a popular sport. Due to high impact and quick movement, there is an enormous load on the lower extremities which increases the risk for injury. Aim: The aim of this study was to investigate the relationship between the quadricep and hamstring strength and the prevalence of lower extremity injuries in netball players. Setting: Twenty-five female netball players (age: 20.8 ± 1.4 years) voluntarily participated. Methods: The Cybex Isokinetic dynamometer was used to determine concentric knee torques. Quadriceps:hamstring strength ratio was determined. Occurrence of lower extremity injuries was documented bi-weekly. Results: Medium effect sizes were noted for flexion torque:work for the left leg and for the quadriceps:hamstring ratio (≥60%) for the right leg. All the other measured variables have a small effect size. 18.75% of lower extremity injuries and ConQ:ConH of Conclusion: Injuries to the ankle and knee are especially common among netball players. Hamstring and quadriceps muscle asymmetry (>10%) were found to be a potential indicator of lower extremity injury. Contribution: This study highlights awareness on lower extremity injuries and the strength ratio between the quadriceps and hamstrings. This can aid coaches and netball players to lower the risk for injuries and thus improve individual- and team performance.

Correlation of Hamstring Tendon Size in Pre-Operative MRI Measurement with Intra-Operative Graft Size in Primary Anterior Cruciate Ligament (ACL) Reconstruction

Background: The size of Hamstring autograft of less than 8.0 mm in ACL re-construction is one of the key factors that may contribute to the failure of the graft. In this study, we are going to assess the correlation of pre-operative MRI measurement of Hamstring tendons with the intra-operative ACL graft. Thus, it may help surgeons to anticipate the needs for graft augmentation should the final graft size be smaller than expected. Methods: We retrospectively re-viewed 41 cases of ACL reconstructions in which MRI were done pre-operatively, in Hospital Pakar Sultanah Fatimah (HPSF), Muar between January 2019 until December 2022. MRI measurements of Hamstring tendon (semitendinosus: ST, and gracilis) were done by a radiologist, and the in-tra-operative notes were reviewed for the final graft size. Pearson’s correlation coefficients were calculated to determine the relationship between graft size and tendon cross-sectional area. The intraclass correlation (ICC) by using two-way mixed model with type consistency, the reliability based on average measure was 0.41 (95% CI: ?0.10, 0.69). A p-value < 0.05 was considered sig-nificant. Results: Of 105 patients with primary ACL reconstruction done be-tween January 2019 to December 2022, only 41 patients were included in this study. There was fair correlation (p = 0.048) between pre-operative MRI measurement and the graft diameter intra-operatively. The mean of 17.0 mm of combined diameter of ST and gracilis tendon in MRI may results in graft diameter of 8.3 mm. There was also positive correlation between patients’ height and the intra-operative graft size. Conclusion: These results showed good correlation between pre-operative MRI measurement of Hamstring ten-don size with the intra-operative graft size, hence it is a reliable tool to predict the Hamstring autograft size in ACL reconstruction.

Comparative study of the clinical efficacy of all-inside and traditional techniques in anterior cruciate ligament reconstruction

BACKGROUND Many studies have focused on the femoral tunnel technique and fixation method,but few studies have involved the tibial tunnel technique and fixation method.The all-inside technique is one of the new techniques that has been described in recent years.All-inside anterior cruciate ligament(ACL)reconstruction is based on a tibial socket instead of a full tunnel.This method has many potential advantages.AIM To compare clinical outcomes of knee ACL autograft reconstruction using allinside quadrupled semitendinosus(AIST)and traditional hamstring tendon(TBT)techniques.METHODS From January 2017 to October 2019,the clinical data of 80 patients with ACL reconstruction were retrospectively analyzed,including 67 males and 13 females.The patients had an average age of 24.3±3.1 years(age range:18-33 years).The AIST technique was used in 42 patients and the TBT technique was used in 38 patients.The time between operation and injury,operative duration,postoperative visual analogue scale(VAS)score and knee functional recovery were recorded and compared between the two groups.The International Knee Documentation Committee(IKDC)and Lysholm scoring system were used to comprehensively evaluate clinical efficacy.RESULTS Eighty patients were followed for 24-36 mo,with an average follow-up duration of 27.5±1.8 mo.There were no significant differences in the time between surgery and injury,operative duration,IKDC and Lysholm scores of the affected knee at the last follow-up evaluation between the two groups.There were significant differences in VAS scores 1 d,3 d,7 d,2 wk and 1 mo after surgery(P<0.05).There was no significant difference in VAS score at 3 mo,6 mo and 1 year after operation.CONCLUSION The efficacy of the AIST ACL reconstruction technique was comparable to the TBT technique,but the postoperative pain was less with the AIST technique.Thus,the AIST technique is an ideal treatment choice for ACL reconstruction.

自体Hamstring腱重建前交叉韧带术后关节镜下再视观察

目的关节镜再视观察游离Hamstring腱重建前交叉韧带后在体内重塑与转归过程.方法关节镜下再视手术,观察关节镜下自体同侧游离Hamstring腱重建前交叉韧带33例.重建术至再视手术时间为2～36个月,平均11.9月.依据重建术至再视术的时间,替代腱按时段分组:1月～,4月～,7月～,10月～,13月～,18月～和25月～组.再视术重点观察评估了移植的Hamstring腱形状、色泽、张力、覆盖的滑漠组织和血管状况.结果再视关节镜下重建前交叉韧带的Hamstring腱随植入时间延长,其形态逐步向正常前交叉韧带重塑与转归;7月～组和此后各组的替代腱在关节镜视下表现为.一种几乎无滑膜和血管的灰白色粗壮的圆柱体,类似于正常的前交叉韧带组织,达到了在体内成熟的程度.结论自体游离多股Hamstring腱重建前交叉韧带术后具有良好早期存活,快速再血管化和重塑过程,其术后的重塑与成熟过程与自体髌腱的过程相似,但其在体内重塑与转归进程相对较快.

关节镜下自体Ha mstring腱重建前交叉韧带的应用

目的 探讨关节镜下自体Hamstring腱重建前交叉韧带 (AnteriorCruciateLigament,ACL)的临床方法和疗效。 方法 2 2例ACL损伤 ,年龄 17岁～ 5 0岁 ,平均 30 7岁 ,进行关节镜下自体Ham string腱ACL重建术。 结果 本组 2 2例术后膝关节均获正常活动范围。术后Lachmen试验 :19例≤ 1+,2例 2 +,1例 3+。轴移试验 :2 0例阴性或可疑 ,2例阳性。术后Lysholm评分为 (87 7± 9 6 )分 ,较术前 (5 4 4± 12 1)分显著提高 (t =2 33,p <0 0 5 )。术后Tegner活动评分为 (5 1± 1 3)分 ,较术前 (2 8±0 8)分显著提高 (t=4 36 ,p <0 0 1)。 19例X线内固定物的位置良好 ,3例内固定物的位置欠佳。 3例胫部伤口早期感染 ,经伤口处理愈合。 2 2例随访 7月～ 2 5月 ,平均 15 7月。 结论 关节镜下自体Ham string腱重建ACL是一种治疗急慢性ACL损伤的有前景的术式。

Effectiveness of exercise for osteoarthritis of the knee:A review of the literature

Osteoarthritis(OA)of the knee is the most common type of arthritis and the major cause of chronic musculoskeletal pain and mobility disability in the elderly.The objective of this paper is to discuss the effectiveness of exercise for OA of the knee based on a review of the literature.We reviewed the relevant literature,i.e.systematic reviews and meta-analyses searched using PubMed.Muscle strengthening and aerobic exercises are effective in reducing pain and improving physical function in patients with mild to moderate OA of the knee.

Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training

Background:Eccentric exercise increases muscle fascicle lengths;however,the mechanisms behind this adaptation are still unknown.This study aimed to determine whether biceps femoris long head(BFlh)fascicle length increases in response to 3 weeks of eccentric exercise training are the result of an in-series addition of sarcomeres within the muscle fibers.Methods:Ten recreationally active participants(age=27±3 years;mass=70±14 kg;height=174±9 cm;mean±SD)completed 3 weeks of Nordic hamstring exercise(NHE)training on a custom exercise device that was instrumented with load cells.We collected in vivo sarcomere and muscle fascicle images of the BFlh in 2 regions(central and distal)by using microendoscopy and 3 dimension ultrasonography.We then estimated sarcomere length,sarcomere number,and fascicle length before and after the training intervention.Results:Eccentric knee flexion strength increased after the training(15%;p<0.001;η_(p)^(2)=0.75).Further,we found a significant increase in fascicle length(21%;p<0.001;η_(p)^(2)=0.81)and sarcomere length(17%;p<0.001;ηp2=0.90)in the distal but not in the central portion of the muscle.The estimated number of sarcomeres in series did not change in either region.Conclusion:Fascicle length adaptations appear to be heterogeneous in the BFlh in response to 3 weeks of NHE training.An increase in sarcomere length,rather than the addition of sarcomeres in series,appears to underlie increases in fascicle length in the distal region of the BFlh.The mechanism driving regional increases in fascicle and sarcomere length remains unknown,but we speculate that it may be driven by regional changes in the pas sive tension of muscle or connective tis sue adaptations.

Graft choices for anterolateral ligament knee reconstruction surgery: Current concepts

The anterolateral ligament(ALL)is a primary structure of the anterolateral complex of the knee that contributes to internal rotational stability of the joint.Injury of the ALL is commonly associated with rupture of the anterior cruciate ligament.If left untreated,ALL lesions may lead to residual anterolateral rotational instability of the knee after anterior cruciate ligament reconstruction,which is a common cause of anterior cruciate ligament graft failure.The function of the ALL can be restored by lateral extraarticular tenodesis or anterolateral ligament reconstruction(ALLR).In the lateral extraarticular tenodesis procedure,a strip of the iliotibial band is placed in a non-anatomical position to restrain the internal rotation of the tibia,while in ALLR,a free graft is fixed at the insertion points of the native ALL.Gracilis and semitendinosus grafts have mainly been utilized for ALLR,but other autografts have also been suggested.Furthermore,allografts and synthetic grafts have been applied to minimize donor-site morbidity and maximize the size and strength of the graft.Nevertheless,there has been no strong evidence to fully support one method over another thus far.The present review presents a detailed description of the graft choices for ALLR and the current literature available in regard to the effectiveness and outcomes of published surgical techniques.

Stretching in the prevention of hamstring strains: Attitudes, beliefs and current practices among football coaches in Mauritius

Context and Objective: Hamstring strain is a common injury in football and it causes a significant amount of time lost from competition and training. Since poor flexibility is thought to predispose to muscle strain, stretching is routinely recommended during warm-up routines by coaches to prevent injuries. However, available evidence suggests that pre-exercise stretching (PES), especially static stretching, has no benefit on injury rates and may even reduce performance in explosive type activities. We designed this study to assess the attitudes, beliefs and practices of football coaches regarding stretching in the prevention of hamstring strains. Design: A cross-sectional survey. Setting: Mauritius Football Association (MFA). Participants: 26 football coaches registered with the MFA. Intervention: Questionnaires were distributed to football coaches of the MFA via sports officers. Questionnaires were then collected two weeks after distribution. Main Outcome Measures: Attitudes, beliefs and practices of football coaches regarding stretching in the prevention of ham-string strains. Results: MFA coaches held generally positive attitudes and beliefs towards stretching. 88% of coaches felt that PES is beneficial and 93% believed that PES prevents hamstring strains. The majority of coaches recommended stretching after warming up (81%) and after the training session (93%). 76% of coaches also advised stretching outside the training sessions. 96% of coaches used static stretching to stretch the hamstrings. The hamstrings were stretched on average for 4 times at each training session and the mean duration of a static stretch was 12 seconds. Conclusions: Nearly all coaches believed that PES prevents hamstring strains although evidence is limited. Some of the coaches’ beliefs and practices were not in line with current recommendations. Coaches reported that their stretching practices would be most likely influenced by scientific research. Thus there is an urgent need to devise awareness and training programmes in this area.

Autologous Tendon Grafts Used in Upper Limb Surgery

Tendon autografts play an important role in upper limb reconstruction and a working knowledge of tendon autograft options is essential for the surgeon. Although palmaris longus is often the first choice, other options like plantaris, extensor Hallucis longus, flexor carpi radialis are readily available. Advantages of autografts include easy availability, satisfactory biomechanical properties and the human body tends to accept its own tendons than from a donor. This review highlights the various options available and their anatomical and surgical considerations in procuring grafts for upper limb reconstructive work.

MRI Observations of Patellar Tendon Length Change after ACL Reconstruction with Hamstring Autografts

The post-operative patellar tendon length was studied to evaluate the possible tendon length change after anterior cruciate ligament（ACL） reconstruction with hamstring autografts. The Insall-Salvati index, modified Insall-Salvati index, curved modified Insall-Salvati index and Caton-Deschamps index were observed by MRI during a follow-up period of 12 weeks on 20 ACL reconstructed knees. The results showed no patellar baja or alta pre-existed on those ACL injured patients. After a follow-up period of 12 weeks, no patellar tendon length change was observed. It is suggested that the change of patella was not the primary reason that may contribute to the premature patellofemoral joint osteoarthritis after ACL reconstruction.

Nordic Hamstring跪姿前倾离心训练的生理效应及其对腘绳肌拉伤的预防效果

腘绳肌拉伤是足球运动中高发生率和高复发率的非接触损伤之一。近些年来,Nordic Hamstring跪姿前倾离心训练(下称NH训练)以其形式简单且无器械设备要求的特点,成为备受关注的预防腘绳肌拉伤的干预手段。研究表明,NH训练能选择性募集并强化半腱肌和股二头肌短头,提高腘绳肌屈膝离心肌力并增加股二头肌长头肌束长度,但对股二头肌长头募集不足,难以强化最易产生拉伤的股二头肌长头。在一定依从性前提下,NH训练对低龄(低于27岁)且无拉伤史的低风险球员腘绳肌拉伤具有预防效果,对高龄或有拉伤史的高风险球员则无预防效果,原因在于NH训练的生理效应仅能改善低风险球员的主要危险因素。建议开展对我国足球运动员的NH干预研究,优化针对低风险球员的NH训练方案,并设计针对高风险球员的预防干预;同时,进一步探索NH训练的生理效应、腘绳肌的募集模式以及离心训练的适应机制。

Injury rate,mechanism,and risk factors of hamstring strain injuries in sports:A review of the literature

Hamstring strains are one of most common sports injuries.The purpose of this literature review is to summarize studies on hamstring strain injury rate,mechanism,and risk factors in the last several decades with a focus on the prevention and rehabilitation of this injury.Hamstring injury commonly occurs in sporting events in which high speed sprinting and kicking are frequently performed,such as Australian football. English rugby,American football,and soccer.Basic science studies have demonstrated that a muscle strain injury occurs due to excessive strain in eccentric contraction instead of force,and that elongation speed and duration of activation before eccentric contraction affect the severity of the injury.Hamstring strain injury is likely to occur during the late swing phase and late stance phase of sprint running.Shortened optimum muscle length,lack of muscle flexibility,strength imbalance,insufficient warm-up,fatigue,lower back injury,poor lumbar posture,and increased muscle neural tension have been identified as modifiable risk factors while muscle compositions,age,race,and previous injuries are non-modifiable risk factors.The theoretical basis of some of these risk factors,however,is lacking,and the results of clinical studies on these risk factors are inconsistent.Future studies are needed to establish the cause-and-effect relationships between those proposed risk factors and the injury.

Anterior cruciate ligament reconstruction best practice: A review of graft choice

There is much literature about differing grafts used in anterior cruciate ligament(ACL) reconstruction. Much of this is of poor quality and of a low evidence base. We review and summarise the literature looking at the four main classes of grafts used in ACL reconstruction; bone-patella tendon-bone, hamstrings, allograft and synthetic grafts. Each graft has the evidence for its use reviewed and then compared, where possible, to the others. We conclude that although there is no clear "best" graft, there are clear differences between the differing graft choices. Surgeon's need to be aware of the evidence behind these differences, in order to have appropriate discussions with their patients, so as to come to an informed choice of graft type to best suit each individual patient and their requirements.

Effects of flexibility and strength training on peak hamstring musculotendinous strains during sprinting

Background:Hamstring injury is one of the most common injuries in sports involving sprinting.Hamstring flexibility and strength are often considered to be modifiable risk factors in hamstring injury.Understanding the effects of hamstring flexibility or strength training on the biomechanics of the hamstring muscles during sprinting could assist in improving prevention strategies and rehabilitation related to these injuries.The purpose of this study was to determine the effects of altering hamstring flexibility or strength on peak hamstring musculotendinous strain during sprinting.Methods:A total of 20 male college students(aged 18-24 years)participated and were randomly assigned to either a flexibility intervention group or a strength intervention group.Each participant executed exercise training 3 times a week for 8 weeks.Flexibility,sprinting,and isokinetic strength testing were performed before and after the 2 interventions.Paired t tests were performed to determine hamstring flexibility or strength intervention effects on optimal hamstring musculotendinous lengths and peak hamstring musculotendinous strains during sprinting.Results:Participants in the flexibility intervention group significantly increased the optimal musculotendinous lengths of the semimembranosus and biceps long head(p<0.026)and decreased peak musculotendinous strains in all 3 bi-articulate hamstring muscles(p<0.004).Participants in the strength-intervention group significantly increased the optimal musculotendinous lengths of all 3 hamstring muscles(p<0.041)and significantly decreased their peak musculotendinous strain during sprinting(p<0.017).Conclusion:Increasing hamstring flexibility or strength through exercise training may assist in reducing the risk of hamstring injury during sprinting for recreational male athletes.

A Single Bundle Anterior Cruciate Ligament Reconstruction (ACL-R) Using Hamstring Tendon Autograft and Tibialis Anterior Tendon Allograft:A Comparative Study

The main purpose of this study patients undergoing a single bundle anterior was to compare the clinical outcomes of cruciate ligament reconstruction (ACL-R) of using quadrupled hamstring (4HT)autografts and two-strand tibialis anterior (2TA) aUografts,and to find out the rate of graft failure and possible causes.We hypothesized that there would be no difference in the clinical outcome,and graft failure would be associated with the use of small sized allograft in young active males with high demand of sports activities.We retrospectively evaluated 222 patients (male,n=167,female,n=55) undergoing ACL-R between January 2010 and July 2014.Of 222 patients,115 were included in the 4HT autograft group and 107 patients in the 2TA allograft group.Inclusion criteria were primary unilateral ACL-R with a minor MCL (<grade Ⅱ)injury with or without meniscus tear and had at least 2.5 years of follow-up.Subjective evaluation was performed using Tegner-Lysholm score,modified Cincinnati knee score,and IKDC knee form.Anteroposterior laxity was assessed using ADT and Lachman test whereas rotational laxity was assessed using pivot shift test.Similarly,functional assessment was performed using range of motion (ROM),Daniel's one-leg hop test,and overall IKDC score.Clinical outcomes were satisfactory and comparable in both groups with no statistically significant difference in all the respective parameters.No statistically significant difference was observed in graft re-rupture rate.However,most graft failures occurred in young active males with high demand of sports activities,graft size smaller than 8 mm,and use of allograft.An autograft with at least 8 mm diameter should be considered in a young active male with high demand of sports activities to avoid graft failure.

Arthroscopic Reconstruction of the Posterior Cruciate Ligament with a Ligament-advanced Reinforcement System and Hamstring Tendon Autograft:A Retrospective Study

Objective:Both ligament-advanced reinforcement system(LARS)and hamstring tendon autograft can serve as grafts for posterior cruciate ligament(PCL)reconstruction.However,few studies have compared the effectiveness of these two approaches.This study therefore aimed to compare the clinical efficacy of arthroscopic reconstruction of the PCL using either the LARS or hamstring tendon autograft.Methods:A total of 36 patients who underwent PCL reconstruction were retrospectively analyzed.Within this cohort,15 patients received a reconstruction using the LARS(LARS group)and 21 using the hamstring tendon autograft(HT group).Results:The pre-and post-operative subjective scores and knee stability were evaluated and the patients were followed up for a period of 2 to 10.5 years(4.11±2.0 years on average).The last follow-up showed that functional scores and knee stability were significantly improved in both groups(P<0.05).Six months after operation,Lysholm scores and IKDC subjective scores were higher in the LARS group than in the HT group(P<0.05).Nonetheless,the last follow-up showed no significant differences in the functional scores or the posterior drawer test between the two groups(P>0.05).In the LARS and HT groups,12 and 9 patients,respectively exhibited KT1000 values<3 mm,with the difference being statistically significant(P<0.05).In the HT group,the diameter of the four-strand hamstring tendon was positively correlated with height(P<0.05),which was 7.37±0.52 mm in males and 6.50±0.77 mm in females(P<0.05).Conclusion:Both LARS and hamstring tendon approaches achieved good efficacy for PCL reconstruction,but patients in the LARS group exhibited faster functional recovery and better knee stability in the long term.LARS is especially suitable for those who hope to resume activities as early as possible.

Hamstring autograft utilization in reconstructing anterior cruciate ligament:Review of harvesting techniques,graft preparation,and different fixation methods

Rupture of the anterior cruciate ligament(ACL)is a common orthopedic injury.Various graft options are available for the reconstruction of ruptured ACL.Using the hamstring muscle as an autograft was first described in 1934,and it remains a commonly harvested graft for ACL reconstruction.Hamstring autografts can be harvested using the traditional anteromedial approach or the newer posteromedial technique.An isolated semitendinosus tendon can be used or combined with the gracilis tendon.There are numerous methods for graft fixation,such as intra-tunnel or extra-tunnel fixation.This comprehensive review discusses the different hamstring muscle harvesting techniques and graft preparation options and fixation methods.It provides a comprehensive overview for choosing the optimal surgical technique when treating patients.

The Effect of Active Knee Extension in Sitting on Lumbopelvic Curvature in Individuals with Clinically Tight Hamstring Muscles: A Cross-Sectional Reliability Study

Relative flexibility between the hamstring and lumbar extensor muscles, which can be evaluated using lumbopelvic curvature during active knee extension in sitting, can sometimes be assessed in physical therapy. However, reliability for its quantitative measure has not been established yet and its establishment was the aim of the current study. Twenty-seven individuals with clinically tight hamstring muscles were recruited. On two separate sessions, the lumbopelvic curvature was evaluated in sitting when the right knee was moved from 90&deg flexion to 10&deg flexion on 15 occasions using a flexible ruler by two examiners on Day 1 and one on Day 2. Lines drawn tangential to the lumbopelvic curvature were traced at T12 and S2 vertebral levels and the angle between the two vertical lines was calculated. Using Day 1 data, the minimum number of repetitions and inter-examiner reliability were assessed. Inter-session reliability was also examined. As a result, there was no statistical difference (P?> 0.05) in the mean absolute difference between the mean value of N-1 and N repetitions (6 ≤ N ≤ 15) in the lumbopelvic curvature angle, indicating that five was considered the minimum number of repetitions. Intraclass correlation coefficient (ICC)(1, 5)?for the inter-session reliability and ICC(2, 5)?for the inter-examiner reliability was 0.97 and 0.93, respectively, indicating excellent reliability. The measure for the lumbopelvic curvature during active knee extension in sitting, which was established in the current study, will be a foundation for further research regarding the relative flexibility of the lumbar and adjunct regions.

Measurement Reliability for Evaluating Lumbopelvic Curvature during Active Knee Extension in Sitting Using a Flexible Ruler in Individuals with Clinically Tight Hamstring Muscles: A Secondary Analysis

In a previous study, we established reliability of a method for determining the angle of lumbopelvic sagittal alignment during active knee extension in sitting (AKEiS) using a flexible ruler and image analysis software (2-point-Method). In addition to this method, a flexible ruler can also be used to measure lumbopelvic sagittal alignment without image analysis software. This study primarily aimed to investigate the minimum number of repetitions, inter-session reliability and inter-examiner reliability of two alternative methods of measurement in a secondary analysis of our previous study. A flexible ruler was used to measure lumbopelvic curvature during AKEiS when the knee reached 10° flexion from 27 individuals with clinically tight hamstring muscles and subsequently analyzed. Lumbopelvic sagittal alignment was evaluated for the region between T12 and S2 using the maximum depth to the curvature (Max-Method) or depth to the curvature at the middle point between T12 and S2 vertebral levels (Mid-Method). It was determined that four repetitions for the Max-Method and 11 repetitions for the Mid-Method were required for the minimum number of repetitions, respectively. Inter-session reliability and inter-examiner reliability were assessed using Intraclass Correlation Coefficients and were 0.91 and 0.91 for the Max-Method and 0.90 and 0.91 for the Mid-Method, respectively. The current study suggests that the Mid-Method would not be recommended for use in the clinical setting as 11 repetitions of data sampling is required. The 2-point-Method or Max-Method may be promising but the ideal measurement method will be identified when the validity of these methods has been established.