膝关节板股韧带的解剖学与临床研究

目的 调查板股韧带(meniseofemoral ligaments,MFLs)发生率,研究MFLs紧张-松弛模式,确定其股骨止点大小、形态及其与后十字韧带(posterior cruciate ligament,PCL)股骨止点位置关系,探讨MFLs功能及其在PCL双束重建股骨骨道定位中的作用.方法 解剖研究:30例成人膝关节标本,调查MFLs发生率,研究MFLs在屈伸膝过程中的紧张一松弛模式及其作用,测量其股骨止点面积,确定其股骨止点与PCL前外侧束(anterotateral bundle,ALB)及后内侧束(posteromedial bundle,PMB)股骨止点间位置关系.临床研究:89例单独PCL断裂膝关节与23例PCL断裂合并其他韧带损伤膝关节,关节镜下观察MFLs发生情况,确定MFLs股骨止点与ALB及PMB股骨止点间位置关系.结果 解剖研究:Humphry韧带紧张一松弛模式与ALB基本相同,出现率为3％(1／30),其股骨止点近似椭圆形,面积为(18.14±3.05)mm2,位于AIB与PMB交界线的远侧;Wrisberg韧带紧张一松弛模式与PMB相似,出现率为90％(27／30),其股骨止点也近似椭圆形,平均面积为(25.63±7.92)mm2,位于PMB股骨止点的近侧.临床研究:Humphry韧带出现率为1.7％(2／112),Wrisberg韧带出现率为59.8％(67／112),二者均低于解剖学研究结果(P<0.05),PCL合并多发韧带损伤时前、后MFLs出现率分别为O％与13.0％(3／23),二者均低于单独PCL断裂中结果(P<0.05),MFLs股骨止点与ALB及PMB股骨位置关系与解剖学研究结果相同.结论 MFLs发生率与创伤有关,MFLs对膝关节稳定具有一定作用,Wrisberg韧带在深屈膝时具有防止PCL前外束与髁问窝发生撞击的作用,MFLs股骨止点可分别作为ALB与PMB股骨骨道定位标志.PCL重建术及半月板切除术中应尽可能保留MFLs.     

后交叉韧带单、双束重建术式的研究进展

正解剖学目前认为膝关节后交叉韧带(posterior cruciate ligament,PCL)由前外束(anterolateral bundle,ALB)和后内束(posteromedial bundle,PMB)组成。膝关节PCL是膝关节强度最大的韧带,其主要作用是防止正常膝关节胫骨后移[1],一旦断裂损伤,就会引起膝关节后向及旋转不稳定,严     

具有双屈伸运动人工半膝关节假体运动 参数分析及实验性临床研究

 目的 针对儿童股骨下段恶性骨肿瘤的诸多治疗方法中存在的问题, 本课题组首次提出 具有双屈伸运动人工半膝关节(双动半膝关节)的概念, 进行其运动轨迹规律及实验性临床研究。 方法 以Mimics/Geomagic/Pro-E软件的设计路线为技术路线。基于成人膝关节标本的CT数据, 利用数控铣床 机加工制作双动半膝关节假体, 进行体外实验研究其运动参数特点, 最后进行实验性临床研究。 结果 离体实验结果:股骨内侧髁屈曲面球心位移在正常膝关节组为(2.59±0.43)mm, 双动半膝关节组为 (2.22±0.52)mm, 全膝关节组为(1.18±0.43)mm;股骨外侧髁屈曲面球心位移在正常膝关节组为(11.95± 6.62)mm, 双动半膝关节组为(11.25±6.19)mm, 全膝关节组为(1.26±0.42)mm;相对胫骨最大旋转角度 在正常膝关节组为13.17°±7.58°, 双动半膝关节组为11.69°±6.49°, 全膝关节组为5.40°±1.29°。完成探索 性临床试验, 术后患者恢复良好, 效果满意。 结论 运动参数分析证明双动半膝关节接近正常膝关节运 动模式, 双动半膝关节为治疗儿童股骨下段恶性肿瘤提供了全新的理念和思路, 新型附丽概念和新型 韧带附丽装置为膝关节韧带功能重建提出新的解决方案。     

数字化导航模板辅助全膝关节置换的模拟研究

 目的 探讨数字化导航模板辅助全膝关节置换的准确性和可行性。方法 取成年尸体下肢标本 20具,随机分为导航模板组和传统方法组,每组 10具 20个膝关节。导航模板组术前行下肢全长 CT扫描,利用逆向工程软件对 CT数据进行处理,设计与股骨远端和胫骨近端匹配的可定位截骨平面和外旋轴的导航模板,通过快速成型机制作模板实物用于尸体标本的全膝关节置换手术操作。传统方法组按常规全膝关节置换手术操作。术后通过 CT扫描比较两种方法定位的截骨准确性。结果 导航模板与股骨髁和胫骨平台贴合紧密,无明显移动。导航模板组 18个膝关节的股骨远端和胫骨近端截骨面与下肢机械轴垂直,2个膝关节内翻; 17个膝关节后髁截骨面与通髁轴完全平行,3个膝关节有成角。传统方法组 20个膝关节均出现下肢机械轴内外翻,其中 5个膝关节大于 5°; 20个膝关节均出现后髁截骨面与通髁轴成角,其中 10个膝关节大于 3°。结论 导航模板法的股骨远端、胫骨近端和股骨外旋截骨准确性均高于传统手术方法。     

Ilizarov技术治疗创伤性膝关节屈曲挛缩畸形

 目的 探讨采用Ilizarov 技术治疗创伤性膝关节屈曲挛缩畸形的疗效。 方法回顾性分 析 2006 年1 月至2010 年12 月采用Ilizarov 技术治疗6 例创伤后膝关节屈曲挛缩畸形男性患者的资料, 年龄9~43 岁, 平均24.5 岁;术前膝关节屈曲畸形35°~85°, 平均47.6°;膝关节活动度0°~70°, 平均 15.8°。其中5 例为膝关节陈旧性骨折伴马蹄足畸形, 畸形角度为25°~37°, 平均31.8°;1 例为股骨髁上骨 折。采用环型外固定架逐渐矫正屈膝和马蹄足畸形, 其中4 例因膝关节骨性结构严重破坏且软组织条 件差, 在膝关节恢复伸直位后行膝关节融合术;另2 例膝关节恢复伸直位后, 白天松开螺母活动膝关 节, 睡觉时将膝关节固定在伸直位, 1 个月后去除外固定架改长腿支具保护3 个月。 结果 术后随访 12~22个月, 平均18 个月。6 例患者膝关节屈曲角度由术前47.67°±18.63°恢复到屈曲9.33°±3.50°。5 例 伴马蹄足畸形患者踝关节跖屈角度由术前31.80°±4.65°恢复到术后3.00°±4.47°。4 例患者术后膝关节成 功融合, 2 例膝关节活动度分别为30°和75°。术后6 例患者均可拄手杖行走。术后2~4 个月, 4 例患者出 现针道感染, 经口服抗生素及使用双氧水清洁针道后约2 周感染控制。 结论 采用Ilizarov 技术可有效 治疗创伤后膝关节屈曲畸形。对膝关节骨性结构损伤且软组织条件较差的患者可行膝关节融合术。     

后交叉韧带胫骨止点与双束重建胫骨骨道定位的临床解剖学研究

目的 解剖研究后交叉韧带(PCL)胫骨止点情况,确定PCL前外侧束(ALB)与后内侧束(PMB)胫骨止点的位置、形状与面积,探讨PCL双束四骨道重建中胫骨骨道定位标志与定位方法.方法 30例成人膝关节标本,根据屈伸膝关节过程中纤维束紧张与松弛情况,将PCL分为ALB与PMB,并确定各束中的功能束,用多种指标测量ALB、PMB与功能束的胫骨止点,解剖寻找双束四骨道重建PCL中胫骨骨道定位标志与定位方法.结果 PCL胫骨止点位于后髁间窝内,其纵轴由近内斜向远外,与胫骨干夹角平均为(16.5±1.4)°.ALB与PMB胫骨止点基本呈远近排列,ALB胫骨止点接近于菱形,平均面积为(90±20)mm2,PMB胫骨止点近似长方形,平均面积(96±32)mm2,二者无显著差异(P>0.05).ALB与PMB中均存在功能束,分别止于ALB胫骨止点的远外侧部及PMB胫骨止点的远内侧部,均接近椭圆形,面积分别为(35±12)mm2与(36±6)mm2,二者无显著差异(P>0.05).ALB功能束胫骨止点中心与PMB功能束胫骨止点中心距离为(12.7 ±1.9)mm.胫骨内、外侧髁间棘及胫骨上端后方骨嵴为重要的解剖标志.结论 PCL胫骨止点可以容纳两个胫骨骨道,PCL的ALB与PMB中均存在功能束,提示临床双束四骨道重建PCL时,胫骨骨道应分别定位于ALB与PMB功能束胫骨止点处.     

一期全膝关节置换术治疗膝关节骨关节炎合并关节外畸形

 目的 探讨膝关节骨关节炎合并关节外畸形患者一期行全膝关节置换术(total knee arthroplasty,TKA)的可行性及其疗效。方法 2006年6月至2010年4月对9例骨关节炎合并关节外畸形患者行一期TKA.男 2例, 女7例;年龄 34~69岁,平均 51岁。股骨侧畸形5例.胫骨侧畸形4例;除 1例畸形由发育不良引起外.其余 8例均由骨折畸形愈合造成。结果 术后随访时间 7~54个月,平均 29个月。 HSS评分从术前平均 18.7分(6~39分).提高到术后平均 89.8分(81~96分)。膝关节活动度由术前平均 46.7°(0°~100°).提高到术后平均 100.6°(85°~115°)。下肢力线由术前平均偏移 11.8°(2°~21°)减少到术后平均偏移 1°(0°~4°);未发现假体松动征象。除 1例患者随访发现截骨处延迟愈合外.其余患者均无感染、下肢深静脉血栓、膝关节不稳及髌骨问题等并发症。结论虽然伴有关节外畸形的膝关节骨关节炎患者一期行 TKA手术难度较大.但通过制定合理的手术方案可以取得与普通 TKA相似的手术效果。如果可行.推荐采用关节内代偿性截骨加软组织平衡术矫正畸形。     

正向、反向束间构型在前十字韧带双束重建中的临床效果比较

 目的比较关节镜下前十字韧带(anterior cruciate ligament. ACL)双束重建中正向、反向束间构型的初期临床效果。方法 2008年 4月至 2009年 8月.采用 8股自体腘绳肌肌腱双束重建 ACL治疗单纯 ACL损伤患者 97例.根据患者入: 时住: 号的奇偶数随机分成正向组(采用正向束间构型. 47例)和反向组(采用反向束间构型.50例).移植物均采用微型钢板纽扣进行悬吊式固定。术后患者随访期均超过 1年.根据 IKDC、Lysholm和 Tegner评分标准进行膝关节功能评估。结果术后随访 12~17个月.平均(13.71±1.32)个月。末次随访时.正向组 2例(4.2%)患者伸膝活动受限 10°.5例(10.6%)膝关节轻度屈曲受限(均<15°);反向组所有患者伸膝活动正常.4例(8.0%)屈曲受限约 5°。根据 Lachman试验.正向组 1例(2.1%)I度阳性和 1例(2.1%) II 度阳性.反向组 1例(2.0%) II 度阳性。 KT-1000(屈膝 30°.30N)双膝松弛度差异值正向组为(1.04±1.11) mm.反向组为(0.86±1.12) mm。按照 IKDC客观评级标准.正向组 46例(97.9%)正常或接近正常.反向组 48例(96.0%)正常或接近正常。根据 IKDC、 Lysholm和 Tegner评分标准.两组的差异均无统计学意义。结论采用 8股自体腘绳肌肌腱正向、反向束间构型双束重建 ACL均能有效地恢复膝关节稳定性.两组短期临床效果的差异无统计学意义。但反向束间构型能有效地防止移植物和髁间凹的撞击。     

股骨单隧道内分叉双束纤维重建后交叉韧带的实验研究

目的在人膝关节标本上行股骨单隧道分叉双束纤维重建后交叉韧带(posterior cruciate ligament,PCL),探讨其术式的优缺点。方法应用力学试验机对14侧捐赠新鲜冷冻人膝关节标本进行生物力学测试,男12侧,女2侧;年龄20～31岁。标本股骨段长20cm,胫骨段长20cm。首先测量PCL完整时胫骨后移距离和交叉韧带的应变(完整组,n=14);然后切断PCL(切断组,n=14),测量胫骨受力时的后移距离后,再将标本随机分为两组:单束重建组(n=7)和分叉双束重建组(n=7),分别测量屈膝0、30、60、90和120°5个角度时胫骨后移距离和移植韧带的应变。结果胫骨受到100N后向力量,完整组在不同屈膝角度下,胫骨向后移位1.97±0.29～2.60±0.23mm,前外束和后内束纤维交替紧张松弛。切断组膝关节明显松弛,胫骨向后移位达11.27±1.06～14.94±0.67mm,与完整组比较差异有统计学意义(P<0.05);单束纤维重建组,在不同屈膝角度下胫骨向后移位1.99±0.19～2.72±0.38mm,移植韧带持续紧张。双束纤维重建组在不同屈膝角度下胫骨向后移位2.27±0.32～3.05±0.44mm,移植的双束纤维交替紧张,协同作用。组内比较:双束重建组在不同屈膝角度时胫骨向后位移差异无统计学意义(P>0.05),而单束重建组在屈膝90°时与屈膝30、60和120°时相比,胫骨后移增大,差异有统计学意义(P<0.05)。结论股骨单隧道内分叉双束纤维重建PCL术在各屈膝角度均能有效防止胫骨后移,股骨单隧道单束重建术屈膝90°时后移较其他角度时增大。分叉双束重建PCL的两束纤维束交替紧张,生物力学特征更接近于正常PCL。     

腰椎间盘突出症椎体间在体运动的观察

 目的 研究腰椎间盘突出症患者生理载荷下椎体节段间三维运动学特点。 方法L4-5间 盘退变突出患者15 例, 年龄为(40.2±4.1)岁, 为实验组;健康志愿者10 名, 年龄为(54.4±3.5)岁, 为对照 组。受试者腰椎进行薄层CT扫描, 导入三维建模软件中建立椎体模型, 将椎体模型与双荧光透视影像 系统(dual fluoroscopic imaging system, DFIS)捕获的不同运动状态下(站立、屈伸、旋转及侧弯)的腰椎透 视图像进行匹配, 以重现生理载荷下腰椎椎体间三维运动状态。通过测量椎体上的三维坐标系, 获得病 变节段(L4-5)和相邻节段(L3-4)椎体间在体运动学数据。 结果 实验组病变节段(L4-5)在前屈、后伸时, 沿 冠状轴、矢状轴和垂直轴的位移与对照组无明显差别, 沿冠状轴的旋转角度(3.7°±2.1°)较对照组(1.9°± 1.1°)明显增加(P 0.05)。 结论 腰椎间盘突出症患者腰椎三维运动模式与正常人不同, 表现在 病变节段屈伸活动及左右位移增加、沿垂直轴旋转有减少趋势, 而头侧相邻节段位移运动范围增加。     

Effect of posterior cruciate ligament rupture on biomechanical features of the medial femoral condyle

Objective: To investigate the biomechanical impact of rupture of the posterior cruciate ligament (PCL) and its various bundles on the medial femoral condyle. Methods: Twelve fresh human cadaveric knee specimens were divided into four groups: PCL intact, anterolateral band (ALB) rupture, posteromedial band (PMB) rupture and PCL complete rupture groups according to the purpose and order of testing. Strain in the middle of the medial femoral condyle was measured under different loads (200–800 N) at 0°, 30°, 60°, and 90° of knee flexion. Results: At 0° of knee flexion, compared with the PCL intact and ALB rupture groups, strain on the medial femoral condyle increased in the PMB rupture and PCL complete rupture groups under all loading conditions. There was no statistical difference between the PMB rupture and PCL complete rupture groups. At 30°, 60° and 90° of knee flexion, compared with the PCL intact group, increase in strain on the medial femoral condyle was noted in the ALB rupture group under higher loading conditions (600 N and 800 N) and PCL complete rupture group under all loading conditions. The PCL complete rupture group had higher strain on the medial femoral condyle than did the ALB rupture group under most loading conditions. Conclusion: At 0° of knee flexion, PMB rupture or PCL complete rupture can cause increase in strain on the medial femoral condyle. However, at 30°, 60° and 90° of knee flexion, ALB rupture or PCL complete rupture can cause increase in strain on the medial femoral condyle.     

Sagittal flexion of the femoral component affects flexion gap and sizing in total knee arthroplasty

The purpose of this study was to determine how much sagittal rotation of the femoral component affects the flexion gap and femoral component sizing using a computer-simulation technique. The study comprised 25 knees scheduled for total knee arthroplasty (TKA). The femoral component was positioned at -2°, 0°, 2°, 4°, or 6° of flexion to the anterior femoral cortex, and the resected portion of the posterior medial femoral condyle was measured for 3 total knee systems. The amount of the resected bone of the posterior medial condyle decreased approximately 1 mm for every 2° of additional flexion in all TKA systems. Intentional sagittal flexion of the femoral component by several degrees during TKA can be a useful downsizing technique for the femoral component without excessively increasing the flexion gap.     

Posterior Cruciate Ligament

Improved understanding of the anatomy and biomechanics of the posterior cruciate ligament (PCL) has led to the evolution and improvement of anatomic-based reconstructions. The PCL is composed of the larger anterolateral bundle (ALB) and the smaller posteromedial bundle (PMB). On the femoral side, the ALB spans from the trochlear point to the medial arch point on the roof of the notch, while the PMB occupies the medial wall from the medial arch point to the most posterior aspect of the articular cartilage. Because of these broad and distinct attachments, the bundles have a load-sharing, synergistic and codominant relationship. Both restrict posterior translation; however, the ALB has a proportionally larger role in restricting translation throughout flexion, whereas the PMB has a role comparable to that of the ALB in full extension. In addition, the PMB resists internal rotational at greater flexion angles (> 90°). Consequently, it is difficult to restore native kinematics with a single graft. Biomechanical analysis of single- versus double-bundle PCL reconstructions (SB PCLR vs DB PCLR) demonstrates improved restoration of native kinematics with a DB PCLR, including resistance to posterior translation throughout flexion (15°-120°) and internal rotation in deeper flexion (90°-120°). Similarly, clinical research demonstrates excellent outcomes following DB PCLR, including functional outcomes comparable to those of anterior cruciate ligament reconstructions, with no significant differences between isolated and multiligament PCL injuries. Compared to SB PCLR, systematic review has demonstrated the superiority of DB PCLR based on objective postoperative stress radiography and International Knee Documentation Committee scores in randomized trials. In addition to reconstruction techniques, recent research has identified other factors that impact kinematics and PCL forces, including decreased tibial slope, which leads to increased graft stresses, and incidence of native PCL injuries. As the understanding of these other contributing factors evolves, so will surgical and treatment algorithms that will further improve patients’ outcomes.     

膝后交叉韧带双束重建术中股骨隧道定位的计算机辅助设计研究

目的 :采用现实虚拟互动技术及有限元分析法,探讨膝关节后交叉韧带双束重建术中股骨隧道合理定位及重建术后移植物固定膝关节力学响应。方法:取新鲜冰冻膝关节标本5具,用实验与计算机仿真相结合的方法,重建膝关节三维计算机模型,以实验获得的外部结构运动指标操纵此模型,真实再现人体膝关节屈伸运动。分析模型内部股骨与胫骨关节面在此运动过程中的空间位置变化情况,分别在后交叉韧带前外侧束(ALB)和后内侧束(PMB)股骨端附丽区选取前、后、中、近、远10个测试点,选取胫骨端止点中点,利用软件Geomagic计算连接两关节面各两点间的长度变化。将模型导入软件Ansys,采用四面体单元建立起股骨-胫骨复合体的有限元模型,模拟人体行走中单腿着地情况对模型施加自身体重冲击载荷,分析关节面的受力情况。结果:计算机还原出各运动角度下膝关节骨性结构的空间形态,软件Geomagic的几何计算功能能准确测量股骨各点与胫骨止点间在关节内的长度变化,ALB和PMB相同测试点在不同角度所得关节面两点间长度变化平均值间有显著性差异(P<0.05);且同一角度不同测试点所得数据间亦有显著性差异(P<0.05)。ALB各点中以A2变化最小(1.35±0.19)mm,A1变化最大(5.41±1.22)mm,A2和A3点比较,差异无统计学意义(P=0.913>0.05);PMB各点中以B3点变化最小(1.95±0.04)mm,B1变化最大(5.23±2.21)mm,只有A2、A3和B3点变化范围在2 mm以内。结论 :通过计算机技术能够建立可供分析测量的膝关节模型,能准确的对交叉韧带的长度进行测量。在后交叉韧带双束重建中,前外侧束应以其股骨附丽区上缘的中点(即近测试点)为中心钻孔;后内侧束应以其股骨附丽区上缘(即近测试点)为中心钻孔建立股骨骨隧道。模型为进一步评价重建等长点偏差对术后移植物固定力学环境影响的研究提供基础。     

Effect of partial and complete posterior cruciate ligament transection on medial meniscus: A biomechanical evaluation in a cadaveric model

Background:

The relationship between medial meniscus tear and posterior cruciate ligament (PCL) injury has not been exactly explained. We studied to investigate the biomechanical effect of partial and complete PCL transection on different parts of medial meniscus at different flexion angles under static loading conditions.

Materials and Methods:

Twelve fresh human cadaveric knee specimens were divided into four groups: PCL intact (PCL-I), anterolateral bundle transection (ALB-T), posteromedial bundle transection (PMB-T) and PCL complete transection (PCL-T) group. Strain on the anterior horn, body part and posterior horn of medial meniscus were measured under different axial compressive tibial loads (200-800 N) at 0°, 30°, 60° and 90° knee flexion in each groups respectively.

Results:

Compared with the PCL-I group, the PCL-T group had a higher strain on whole medial meniscus at 30°, 60° and 90° flexion in all loading conditions and at 0° flexion with 400, 600 and 800 N loads. In ALB-T group, strain on whole meniscus increased at 30°, 60° and 90° flexion under all loading conditions and at 0° flexion with 800 N only. PMB-T exihibited higher strain at 0° flexion with 400 N, 600 N and 800 N, while at 30° and 60° flexion with 800 N and at 90° flexion under all loading conditions.

Conclusions:

Partial PCL transection triggers strain concentration on medial meniscus and the effect is more pronounced with higher loading conditions at higher flexion angles.     

Anatomic double-bundle posterior cruciate ligament reconstruction using hamstring tendons

Recent biomechanical studies have shown that an anatomic double-bundle posterior cruciate ligament (PCL) reconstruction is superior in restoring normal knee laxity compared with the conventional single-bundle isometric reconstruction. We describe a modification of an endoscopic PCL reconstruction technique using a double-bundle Y-shaped hamstring tendon graft. A double- or triple-bundle semitendinosus-gracilis tendon graft is used and directly fixed with soft threaded biodegradable interference screws. In the medial femoral condyle, 2 femoral tunnels are created inside-out through a low anterolateral arthroscopic portal. First, in 80° of flexion, the double-stranded gracilis graft is fixed with an interference screw inside the lower femoral socket, representing the insertion site of the posteromedial bundle. In full extension the combined semitendinosus-gracilis graft is pretensioned and fixed inside the posterior aspect of the single tibial tunnel. The double- or triple-stranded semitendinosus tendon is inserted in the higher femoral tunnel, presenting the insertion site of the anterolateral bundle. Finally, pretension is applied to the semitendinosus bundle in 70° of flexion and a third screw is inserted. Using this technique, the stronger semitendinosus part of the double-bundle graft, which mimics the anterolateral bundle of the PCL, is fixed in flexion, whereas the smaller gracilis tendon part (posteromedial bundle) is fixed in full extension. Thus, a fully arthroscopic anatomic PCL reconstruction technique is available that may better restore normal knee kinematics as compared to the single-stranded isometric reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 1 (January), 2001: pp 88–97     

Editorial Commentary: The Posterior Cruciate Ligament Posteromedial Bundle Is Small but Vital to Posterior Cruciate Ligament Biomechanics: Don’t Ignore the Underdog

Posterior cruciate ligament (PCL) reconstruction leads to outcomes less favorable than those of anterior cruciate ligament reconstruction. In recent years, we have seen a surge of publications regarding PCL anatomy, isometry, and reconstruction techniques. PCL reconstruction has been revolutionized with lessons learned from analysis of PCL behavior, such as the distinct role of the posteromedial bundle (PMB) in the biomechanics of the knee at different flexion angles, as well as its co-dominant role with its counterpart, the anterolateral bundle. With the knee in extension, the PMB serves to restrict posterior translation, whereas in knee flexion, the PMB restricts internal rotation. It is rather too early to know whether the biomechanical advantage of double-bundle reconstruction will result in better clinical outcomes in the long term; however, the increased interest and the refinement of both single- and double-bundle reconstruction techniques will certainly advance our knowledge, ultimately translating into better patient outcomes.     

Potential risk of cartilage damage in double bundle ACL reconstruction: impact of knee flexion angle and portal location on the femoral PL bundle tunnel

The aim of this study was to compare the impact of knee flexion angle and the level of the medial drilling portal on a potential damage to the subchondral bone in double bundle ACL reconstruction, drilling the femoral PL tunnel through an accessory medial portal. We hypothesized that a knee flexion angle of 70° and 90° or a high accessory medial portal will result in a potential damage to the subchondral bone of the lateral femoral condyle. In a sawbone knee model, the medial portal location was standardized as 0 mm above the meniscus (low portal) and 10 mm above the meniscus (high portal). Femoral PL bundle tunnels were drilled at three different knee flexion angels: 70°, 90°, and 110° of knee flexion. For each portal, ten specimens were used for every flexion angle. Drilling the PL tunnel through the high medial portal at a knee flexion angle of 70° resulted in damage of the subchondral bone plate in all specimens. At 110° of flexion the distance of the tunnel exit to the subchondral bone plate was significantly higher than at 70° of flexion for both the groups, drilling through the high and low medial portal (P < 0.05). Drilling through the low portal did not result in bone plate damage at 90 and 110° of knee flexion angle. Drilling of the femoral PL bundle tunnel through a high medial portal at low knee flexion angles may damage the subchondral bone of the lateral compartment. In ACL reconstruction restoring the AM and PL bundle separately, high medial portal drilling should be avoided. We recommend drilling of the femoral PL bundle tunnel through a low medial portal in high knee flexion.