自体半腱和股薄肌腱移植双束重建膝关节后外侧角

目的:观察采用自体半腱和股薄肌腱移植双束重建膝关节后外侧角韧带结构的近期临床效果。方法:对21例膝关节后外侧角韧带结构损伤患者(23个膝关节),采用自体半腱和股薄肌腱移植,双束重建膝关节后外侧角韧带结构。自体半腱肌腱移植物经胫骨骨道和腓骨骨道返折分别重建腘肌腱和腘腓韧带,于腘肌腱股骨外侧髁解剖止点处钻孔固定重建的腘肌腱和腘腓韧带;股薄肌腱移植物经腓骨骨道返折重建腓侧副韧带,于腓侧副韧带股骨外侧解剖止点处钻孔固定重建的腓侧副韧带。对于合并交叉韧带损伤者,同期行关节镜下韧带重建术。术后对患者膝关节内翻稳定性和外旋活动度进行至少1年(12~31个月,平均26.7个月)随访,通过Lysholm膝关节评分法评价膝关节术前、术后功能。结果:术后1年以上的回顾性随访中,膝关节完全伸直位无膝内翻不稳定者;屈膝30°位,无膝内翻不稳定者19例,膝内翻Ⅰ度不稳定伴硬性终止点者2例;俯卧位膝关节屈膝30°,所有患者小腿外旋活动均与对侧相同;Lysholm膝关节评分术前平均54.3分,术后平均89.2分。结论:自体半腱和股薄肌腱移植双束重建膝关节后外侧角韧带结构具有移植腱割取创伤小、移植材料理想、解剖等长重建及固定强度高的特点,近期疗效理想。     

膝关节镜下半腱肌及股薄肌肌腱重建前交叉韧带的临床观察

目的探讨膝关节镜下前交叉韧带重建的方法和效果。方法回顾分析26例膝关节镜下应用自体半腱肌及股薄肌腱以界面挤压螺钉及Endobutton固定重建前交叉韧带的临床资料,对患膝关节功能进行评估。结果术后随访12-18个月,根据Lysholm膝关节评分标准,由术前（54．7±9．13）分提高到术后（86．6±6．97）分。结论膝关节镜下采用自半腱肌及股薄肌肌腱重建前交叉韧带的方法可行,疗效满意,可作为重建前交叉韧带的方法广泛应用。     

自体半腱肌腱股薄肌腱重建前交叉韧带术后肌腱再生的临床研究

目的 :应用超声仪观察切取半腱肌腱股薄肌腱重建前交叉韧带后肌腱的再生情况。方法 :39例用自体半腱肌腱股薄肌腱重建前交叉韧带患者 ,术后平均 13个月行双侧半腱肌腱股薄肌腱超声检查 ,了解肌腱再生情况并对比其长度和截面积的变化。结果 :超声检查显示 39例患者中有肌腱再生 2 6例 ,再生率为 72 %。再生肌腱长度和截面积与对侧肌腱相比无明显差异。 2 6例患者半腱肌腱股薄肌肌腹有萎缩。结论 :切取半腱肌腱股薄肌腱重建前交叉韧带后肌腱能够再生。     

关节镜下半腱肌腱股薄肌腱单端固定法重建交叉韧带24例分析

目的总结膝关节镜下同侧半腱肌腱、股薄肌腱单端固定法重建后交叉韧带的方法及疗效,分析其优缺点。方法应用同侧半腱肌腱、股薄肌腱单端固定,重建后交叉韧带损伤24例。结果术后随访6～36个月,平均18个月。按lysholm膝关节评分标准,由术前43分提高到术后93分。结论同侧半腱肌腱、股薄肌腱单端固定法重建后交义韧带创伤小、操作简便,是重建后交叉韧带的理想方法之一。     

关节镜下自体半腱及股薄肌腱重建膝前交叉韧带

 目的 探讨关节镜下以自体半腱肌、股薄肌腱重建膝前交叉韧带(ACL)的手术方法及疗效.方法 自2006年3月～2007年12月,关节镜下绳肌腱修复膝前交叉韧带损伤39例.膝前小切口取半腱肌腱、股薄肌腱修整、对折后成四股,分别建立胫骨隧道及股骨隧道,用Endobutton和生物可吸收挤压螺钉固定肌腱,重建ACL的解剖结构和生理功能.术后即行功能锻练.结果 术后患者伤口均Ⅰ期愈合,8～10周膝关节屈伸功能恢复正常.随访时间3～15个月,平均8个月.抽屉试验和Lachman试验阳性者2例,可疑阳性者6例;余患者均为阴性.根据敖英芳临床判断标准,本组优23例,良11例,中3例,差2例.Lysholm评分术后(87.6±4.6),与术前(45.3±4.2)比较,差异显著(P<0.01).结论 绳肌腱具有良好的抗拉强度和刚度,在关节镜下用四股绳肌腱重建膝前交叉韧带是一种疗效可靠的治疗方式.     

军队人员关节镜下重建前交叉韧带

目的 探讨军人前交叉韧带损伤患者采用自体四股半腱肌腱 股薄肌腱重建前交叉韧带的手术方法及远期疗效.方法 关节镜下以自体四股半腱肌腱 股薄肌腱为前交叉韧带重建替代物,保留少许前交叉韧带残端作为定位标志物,对35例前交叉韧带损伤军人行重建术.结果 术后35例膝关节活动度均恢复至正常范围,无韧带撞击现象,前抽屉试验全部阴性,Lachman试验全部小于Ⅰ度.Lysholm评分由术前的平均52.3分提高到术后的平均88.5分,差异有显著性意义(P＜0.01).大多数患者获得满意治疗效果,可继续从事日常工作.结论 关节镜下自体四股半腱肌腱 股薄肌腱重建前交叉韧带是恢复膝关节稳定性较好的方法.关节镜下重建前交叉韧带是前交叉韧带损伤军人较为理想的手术方式,其创伤较小、卧床时间短、远期疗效较好.     

股薄肌肌腱重建内侧副韧带的力学原理

膝关节内侧副韧带断裂的急性期或慢性期均应采用韧带重建术。作者采用股薄肌肌健重建内侧副韧带15例,临床观察取得了良好结果。为论证该手术方法的优点,我们进行了内侧副韧带和股薄肌腱的力学实验,结果证明内侧副韧带破坏力为2080N,股薄肌肌腱为3060 N,说明股薄肌肌腱重建内侧副韧带是合理的。     

军事训练致膝关节侧副韧带Ⅲ度损伤的手术治疗

目的 探讨手术治疗军事训练所致膝关节侧副韧带Ⅲ度损伤的方法及疗效.方法 军事训练中发生的膝关节侧副韧带Ⅲ度损伤患者16例,采用带线锚钉对侧副韧带止点损伤进行止点修复,对内侧副韧带实质部新鲜性损伤进行直接缝合修复,而陈旧性损伤采用损伤部位直接缝合+股薄肌半腱肌肌腱转位重建加强,对外侧副韧带实质部新鲜及陈旧性损伤均采用半腱...     

神经肌肉电刺激对前交叉韧带重建术后腘绳肌功能的影响

目的:观察神经肌肉电刺激(NMES)对前交叉韧带(ACL)重建术后腘绳肌功能的影响,为预防自体腘绳肌腱重建ACL术后患侧腘绳肌肌力的下降、及早促进膝关节功能恢复提供依据。方法:选取自体腘绳肌重建ACL男性患者30名为对象,随机分为常规康复组、等长收缩组、神经肌肉电刺激(NMES)组,采用BIODEX等速肌力测试仪测试双侧腘绳肌等长肌力,采用Tensiomyography肌肉状态测试分析仪测试电机械延迟(EMD)和收缩持续时间;行IKDC膝关节主观功能评分。结果:术后3个月患侧腘绳肌等长肌力常规组较术前有所下降,而等长收缩组和NMES组则较术前有所增加,且与常规组均有显著性差异(P<0.05)。半腱肌EMD:术后NMES组较常规康复组和等长收缩组增加较少,均有显著差异性(P<0.05,P<0.01)。股二头肌EMD:术后三组受试对象EMD患侧均较健侧增加,等长收缩组较常规康复组有显著差异性(P<0.05)。半腱肌和股二头肌收缩持续时间:三组患者术前和术后无论是健侧还是患侧股二头肌收缩持续时间均无显著差异性。IKDC评分:三组患者术后3个月与术前差值,常规康复组较等长收缩组差异显著(P<0.05)。结论:术后早期应用NMES可以有效地预防自体腘绳肌腱重建ACL术后腘绳肌肌力的下降以及电机械延迟的延长。     

关节镜下4股半腱肌腱单束重建前交叉韧带部分损伤

目的 介绍关节镜下单束蕈建增强治疗前交叉韧带(anterior cruciate ligament,ACL)后外侧束部分损伤方法 ,探讨其临床效果. 方法 对26例单纯ACL后外侧柬部分损伤患者,在关节镜下采用自体半腱肌腱进行单束解剖重建.按照国际膝关节评分委员会(internationalknee documentation committee,IKDC)和Lysholm膝关节功能评分表对患膝功能进行评估,通过KT-1000检查比较膝关节的前向松弛度. 结果 术后无活动受限,屈膝活动度130°～150°,平均142°.术后随访12～18个月,最后随访时IKDC评分为A级25例(96%),B级1例(4%);IKDC评分从术前的(71.4±3.7)分提高到随访结束时的(95.8±3.4)分(t=9.836,P<0.01).屈膝25°位KT-1000检查,双侧膝关节胫骨结节前移差异从术前的(5.1±1.2)mm减少到终末随访的(2.1±1.3)mm(t=10.48,P<0.01).患者术前Lysholm膝关节功能评分为(76.7±3.2)分,终末随访时为(95.7±2.4)分(t=7.356,P<0.01). 结论 在关节镜下采用自体半腱肌腱单束解剖重建增强治疗ACL后外侧束部分损伤,能取得良好效果.     

Anatomical reconstruction of knee posterolateral complex with the tendon of the long head of biceps femoris

BACKGROUND: There is no consensus about the best way to reconstruct the knee posterolateral complex. HYPOTHESIS: Anatomical reconstruction of the knee posterolateral complex with the tendon of the long head of biceps femoris can restore knee posterolateral stability. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Anatomical reconstruction of the fibular collateral ligament, popliteofibular ligament, and popliteus tendon was performed consecutively in 28 patients with chronic posterolateral knee injuries. Two distally pedicled tendon slips more than 16 cm long were created from the tendon of the long head of the biceps femoris. The posterior tendon slip was used to reconstruct the popliteofibular ligament and popliteus tendon, and the anterior slip were doubled to reconstruct the lateral collateral ligament. The patients were followed up for 2 to 4 years. RESULTS: At the latest follow-up, examinations showed that 96.4% (27/28) of the patients had a normal or nearly normal reconstructed fibular collateral ligament as judged by manual examination. All patients had a normal or nearly normal reconstructed popliteofibular ligament and popliteus tendon as judged by manual examination. CONCLUSION: Anatomical reconstruction of the knee posterolateral complex with the tendon of the long head of biceps femoris is effective in restoring knee posterolateral stability.     

MR imaging,MR arthrography,and specimen correlation of the posterolateral corner of the knee: an anatomic study

OBJECTIVE: We sought to evaluate the anatomy of the posterolateral aspect of the knee with anatomic dissection, MR imaging, MR arthrography, and sectional anatomy. MATERIALS AND METHODS: We assessed the posterolateral corner of the knee during dissection of one gross anatomic specimen. MR imaging and MR arthrography were performed in seven additional knee specimens. T1-weighted spin-echo MR images were obtained in the standard imaging planes as well as in the coronal oblique plane. The specimens underwent T1-weighted spin-echo MR imaging after administration of intraarticular contrast material and were sectioned into planes corresponding to those of the MR images. RESULTS: At anatomic dissection, the following posterolateral structures were identified: the arcuate ligament (medial and lateral limbs), fabellofibular ligament, popliteofibular ligament, popliteus tendon and its two posterior attachments to the lateral meniscus, fibular collateral ligament, direct and anterior arms of the tendon of the long head of the biceps femoris muscle, and direct and anterior arms of the tendon of the short head of the biceps femoris muscle. Correlation of MR imaging and anatomic findings showed that the popliteofibular ligament and oblique popliteal ligament were found in 57% and 100% of specimens, respectively. At least one of the two limbs of the arcuate ligament was identified in 71% of specimens. The fabellofibular ligament was not identified on MR images in any of the specimens. The anteroinferior and posterosuperior popliteomeniscal fascicles were identified in all specimens. CONCLUSION: The posterolateral corner of the knee comprises complex and variable anatomic structures. Recognition of these variations is important in the assessment of MR images of the knee.     

MRI of the popliteofibular ligament: isotropic 3D WE-DESS versus coronal oblique fat-suppressed T2W MRI

Objective The objective was to compare isotropic 3D water excitation double-echo steady state (WE-DESS) MRI with coronal oblique fat-suppressed T2-weighted (FS T2W) images in the identification of the popliteofibular ligament (PFL). Materials and methods A prospective analysis of 122 consecutive knee MRIs was performed in patients referred for knee pain from the orthopaedic clinic. In addition to the standard knee sequences, isotropic WE-DESS volume acquisition through the whole knee and coronal oblique FS T2W fast spin echo sequences through the posterolateral corner were obtained. The presence of the popliteus and biceps femoris tendons, lateral collateral and PFL was documented. Anterior cruciate ligament injury was present in 33 cases and these were excluded from the study because of the risk of associated PFL injury, leaving a total of 89 cases. Of the 42 patients in whom arthroscopic evaluation was subsequently obtained, none were found to have an injury to the PFL. Results The lateral collateral ligament, biceps femoris and popliteus tendon were identified in all cases on all sequences. The PFL was seen in 81 (91.0%; 95% CI 85.1–97.0%) patients using the WE-DESS sequence and 63 (70.8%; 95% CI 61.3–80.2%) patients using the coronal oblique FS T2W sequence, a statistically significant difference (p < 0.00005). Conclusion Isotropic 3D WE-DESS MRI significantly enhances our ability to identify the popliteofibular ligament compared with coronal oblique fat-suppressed T2-weighted images.     

Treatment of acute and chronic injuries to the posterolateral and lateral knee

Acute and chronic posterolateral injury is often associated with cruciate injury. Surgical reconstructions for acuteposterolateral instability achieve better results than reconstructions for chronic posterolateral instability, and whenever possible, we perform acute reconstruction of posterolateral injury. First, any associated cruciate injury is reconstructed. Then the posterolateral corner is exposed through an open lateral incision. We attempt to anatomically repair or reconstruct the major supporting structures of the posterolateral corner. They are the lateral collateral ligament, the popliteus, and the popliteofibular ligament. In acute injury we first attempt direct repair, advancement and recession, or augmentation. Occasionally, reconstruction with patellar tendon autografts or allografts or with achilles allografts is required. In the patient with chronic posterolateral instability and varus alignment, a proximal valgus tibial osteotomy is performed. If required, additional posterolateral reconstruction is performed on a staged basis. In the patient with chronic posterolateral instability and valgus alignment, reconstruction with patellar tendon or Achilles allograft is performed. This article reviews the techniques for reconstruction of acute and chronic injuries to the popliteofibular ligament, and popliteal attachment to the tibia and the lateral collateral ligament.     

Anterior rim tibial plateau fractures and posterolateral corner knee injury

The aim of this study was to review MRI findings of clinically suspected posterolateral corner knee injuries and their associated internal derangements. Sixteen knees in 15 patients who had evidence of a posterolateral corner knee injury on the physical exam underwent MRI to evaluate the posterolateral corner of the knee and to look for associated injuries. Two musculoskeletal radiologists reviewed the scans. Surgery was performed on 10 of the knees. Tibial plateau fractures were present in 6 knees; 5 of the fractures were anteromedial rim tibial plateau fractures. The popliteus muscle was injured in 13 knees and the biceps femoris in 6 knees. The lateral collateral ligament was ruptured in 12 knees. The posterior cruciate ligament was completely ruptured in 7 knees and avulsed from its tibial attachment in 1 knee. Eleven knees had a complete anterior cruciate ligament rupture. The anterior cruciate ligament was edematous without complete disruption of all fibers in 3 knees. There was excellent correlation between the MRI results and operative results in regard to the presence of a posterolateral corner injury of the knee (9 of the 10 knees had a posterolateral corner injury). In our study MRI readily detected posterolateral corner injuries. Posterolateral corner injuries of the knee are frequently associated with a variety of significant injuries, including cruciate ligament tears, meniscus tears, and fractures. Fractures of the peripheral anteromedial tibial plateau are not common; however, given their relatively common occurrence in this study, they may be an indicator of a posterolateral corner injury to the knee.     

Posterolateral instability of theknee: treatment using the clancy biceps femoris tenodesis

Posterolateral instability of the knee is perhaps the most challenging injury facing the sports medicine physiciantoday. Diagnosis requires a thorough understanding of the complex anatomy, function, and biomechanics of the posterolateral structures. In isolated cases of posterolateral instability, the physical findings may be subtle and easily overlooked. Similarly, in complex injuries involving the posterolateral structures, the physical findings may be confusing and misdiagnosed as an isolated cruciate ligament injury. Failure to appropriately diagnose and treat a posterolateral injury can lead to significant functional disability and failure of associated ligamentous reconstruction. Optimal results may be achieved if the injury is diagnosed acutely and surgical treatment is carried out promptly with stabilization of the posterolateral structures and any associated ligamentous insufficiencies. The clinical and biomechanical results of the Clancy biceps tenodesis have proven the procedure successful for controlling varus and external rotational laxity. Rerouting of the biceps femoris tendon with tenodesis to the lateral femoral epicondyle creates a new fibular collateral ligament and tightens the posterolateral capsule and arcuate complex. In addition, tenodesis eliminates the dynamic external rotation of the tibia by the biceps femoris muscle, which actively exacerbates posterolateral subluxation. When performed properly, the biceps tenodesis can eliminate posterolateral instability and restore functional stability to the knee.     

An analysis of an anatomical posterolateral knee reconstruction: an in vitro biomechanical study and development of a surgical technique

BACKGROUND: To date, no surgical technique to treat posterolateral knee instability anatomically reconstructs the 3 major static stabilizing structures of the posterolateral knee: the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament. HYPOTHESIS: Static varus and external rotatory stability would be restored to the reconstructed knee with a posterolateral knee injury. METHODS: The anatomical locations of the original fibular collateral ligament, popliteus tendon, and popliteofibular ligament were reconstructed using a 2-graft technique. Ten cadaveric specimens were tested in 3 states: intact knee, knee with the 3 structures cut to simulate a grade III injury, and the reconstructed knee. RESULTS: For the varus loading tests, joint stability was significantly improved by the posterolateral reconstruction compared to the cut state at 0 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion. There were no significant differences between the intact and reconstructed knees at 0 degrees, 60 degrees, and 90 degrees for varus translation. For the external rotation torque tests, external rotation was significantly higher for the cut state than for the intact or reconstructed posterolateral knee. There was no significant difference in external rotation between the intact and reconstructed posterolateral knees at any flexion angle. CONCLUSIONS: This 2-graft technique to reconstruct the primary static stabilizers of the posterolateral knee restored static stability, as measured by joint translation in response to varus loading and external rotation torque, to knees with grade III posterolateral injuries.     

Knee dislocations: a magnetic resonance imaging study correlated with clinical and operative findings

OBJECTIVES: Our objectives were to determine retrospectively the prevalence, patients' demographics, mechanism of injury, combination of torn ligaments, associated intra-articular and extra-articular injuries, fractures, bone bruises, femoral-tibial alignment and neurovascular complications of knee dislocations as evaluated by magnetic resonance (MR) imaging. MATERIALS AND METHODS: From 17,698 consecutive knee examinations by magnetic resonance imaging (MRI) over a 6-year period, 20 patients with knee dislocations were identified. The medical records of these patients were subsequently reviewed for relevant clinical history, management and operative findings. RESULTS: The prevalence of knee dislocations was 0.11% [95% confidence interval (95% CI) 0.06-0.16)]. There were 16 male patients and four female patients, with ages ranging from 15 years to 76 years (mean 31 years). Fifteen patients had low-velocity injuries (75%), of which 11 were amateur sports related and four were from falls. Four patients (20%) had suffered high-velocity trauma (motor vehicle accidents). One patient had no history available. Anatomic alignment was present at imaging in 16 patients (80%). Eighteen patients had three-ligament tears, two had four-ligament tears. The four-ligament tears occurred with low-velocity injuries. The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were torn in every patient; the lateral collateral ligament (LCL) was torn in 50%, and the medial collateral ligament (MCL) in 60%. Intra-articular injuries included meniscal tears (five in four patients), fractures (eight in seven patients), bone bruises (15 patients), and patellar retinaculum tears (eight partial, two complete). The most common extra-articular injury was a complete biceps femoris tendon tear (five, 25%). There were two popliteal tendon tears and one iliotibial band tear. One patient had received a vascular injury following a motor vehicle accident (MVA) and had been treated prior to undergoing MRI. Bone bruises (unrelated to fractures), four-ligament tears, biceps femoris tears, and popliteus tendon tears were encountered only in the low-velocity knee dislocations. Twelve were treated surgically, five conservatively, and three had been lost to follow-up. The biceps femoris tendon was repaired in every patient who was treated surgically. CONCLUSIONS: Knee dislocations occurred more commonly in low-velocity injuries than in high-velocity injuries, predominantly affecting amateur athletes. Biceps femoris tendon tears were the most common extra-articular injury requiring surgery. Neurovascular injury (5%) was uncommon. At imaging, femoral-tibial alignment was anatomic in the majority of patients.     

How well do anatomical reconstructions of the posterolateral corner restore varus stability to the posterior cruciate ligament-reconstructed knee?

BACKGROUND: With grade 3 posterolateral injuries of the knee, reconstructions of the lateral collateral ligament, popliteus tendon, and popliteofibular ligament are commonly performed in conjunction with a posterior cruciate ligament reconstruction to restore knee stability. HYPOTHESIS: A lateral collateral ligament reconstruction, alone or with a popliteus tendon or popliteofibular ligament reconstruction, will produce normal varus rotation patterns and restore posterior cruciate ligament graft forces to normal levels in response to an applied varus moment. STUDY DESIGN: Controlled laboratory study. METHODS: Forces in the native posterior cruciate ligament were recorded for 15 intact knees during passive extension from 120 degrees to 0 degrees with an applied 5 N .m varus moment. The posterior cruciate ligament was removed and reconstructed with a single bundle inlay graft tensioned to restore intact knee laxity at 90 degrees . Posterior cruciate ligament graft force, varus rotation, and tibial rotation were recorded before and after a grade 3 posterolateral corner injury. Testing was repeated with lateral collateral ligament, lateral collateral ligament plus popliteus tendon, and lateral collateral ligament plus popliteofibular ligament graft reconstructions; all grafts were tensioned to 30 N at 30 degrees with the tibia locked in neutral rotation. RESULTS: All 3 posterolateral graft combinations rotated the tibia into slight valgus as the knee was taken through a passive range of motion. During the varus test, popliteus tendon and popliteofibular ligament reconstructions internally rotated the tibia from 1.5 degrees (0 degrees flexion) to approximately 12 degrees (45 degrees flexion). With an applied varus moment, mean varus rotations with a lateral collateral ligament graft were significantly less than those with the intact lateral collateral ligament beyond 0 degrees flexion; mean decreases ranged from 0.8 degrees (at 5 degrees flexion) to 5.6 degrees (at 120 degrees flexion). Addition of a popliteus tendon or popliteofibular ligament graft further reduced varus rotation (compared with a lateral collateral ligament graft) beyond 25 degrees of flexion; both grafts had equal effects. A lateral collateral ligament reconstruction alone restored posterior cruciate ligament graft forces to normal levels between 0 degrees and 100 degrees of flexion; lateral collateral ligament plus popliteus tendon and lateral collateral ligament plus popliteofibular ligament reconstructions reduced posterior cruciate ligament graft forces to below-normal levels-beyond 95 degrees and 85 degrees of flexion, respectively. CONCLUSIONS: With a grade 3 posterolateral corner injury, popliteus tendon or popliteofibular ligament reconstructions are commonly performed to limit external tibial rotation; we found that they also limited varus rotation. With the graft tensioning protocols used in this study, all posterolateral graft combinations tested overconstrained varus rotation. Further studies with posterolateral reconstructions are required to better restore normal kinematics and provide more optimum load sharing between the PCL graft and posterolateral grafts. CLINICAL RELEVANCE: A lower level of posterolateral graft tension, perhaps applied at a different flexion angle, may be indicated to better restore normal varus stability. The clinical implications of overconstraining varus rotation are unknown.     

Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles

A decrease of deep knee flexion torque after anterior cruciate ligament (ACL) reconstruction, using a semitendinosus (and gracilis) tendon, has been reported. However, the cause of this weakness remains controversial. Architectural and functional differences in the knee flexor muscles influence this weakness. the fiber length of the semitendinosus, gracilis, semimembranosus, and biceps femoris were directly measured in six human cadavers. The flexion torque and EMG of the hamstrings were measured in both limbs of 16 patients (23±5 years) after ACL reconstruction (12–43 months post-operation), using ipsilateral semitendinosus tendon. Magnetic resonance imagings were taken, over both the thighs of those patients, to measure muscle volume and to confirm a state of semitendinosus tendon regeneration. The position of the musculotendinous junction of the semitendinosus was also analyzed. The fiber length of the semitendinosus and gracilis were three to four times longer than that of the semimembranosus and biceps femoris. The difference of flexion torque between the normal and ACL reconstructed limbs significantly increased as the knee flexion angle increased. The EMG value for the semimembranosus and biceps femoris of both limbs as well as the semitendinosus of the ACL reconstructed limbs, significantly reduced as the knee flexion angle was increased. The volume of the semitendinosus in the reconstructed limb was significantly smaller than in normal limbs. The regeneration of the semitendinosus tendon was confirmed in all subjects, and the musculotendinous junction position of the reconstructed limb in almost all subjects was found in further image from the knee joint space than that for the normal limb. The decrease of deep knee flexion torque, after ACL reconstruction, could be due to the atrophy and shortening of the semitendinosus after its tendon has been harvested, as well as the lack of compensation from the semimembranosus and biceps femoris, due to the architectural differences between the semitendinosus and the semimembranosus and biceps femoris.