膝内侧半月板“湾征”对内侧副韧带断裂的诊断意义

目的内侧副韧带损伤后,关节镜下可见内侧半月板上滑膜缘完全显示,类似海湾形状,称为"海湾全景征"(简称"湾征"),判断其作为诊断膝内侧副韧带断裂标志体征的可靠性及意义。方法 2007年3月-2011年3月,纳入59例MRI检查提示内侧副韧带断裂患者作为观察组,其中男38例,女21例;年龄16～39岁,平均23.2岁;单纯内侧副韧带断裂12例,合并外侧半月板损伤16例,前交叉韧带损伤27例,前、后交叉韧带损伤3例,髌骨脱位1例。68例MRI检查提示无内侧副韧带断裂患者作为对照组,其中男45例,女23例;年龄25～49岁,平均31.8岁;前交叉韧带损伤38例,前、后交叉韧带损伤4例,前交叉韧带合并外侧半月板损伤26例。两组治疗前后行关节镜探查比较"湾征"出现情况。结果观察组膝内侧副韧带修复重建前关节镜探查均见"湾征",明确内侧副韧带断裂;修复重建后"湾征"消失。对照组交叉韧带重建前后均未见"湾征"。结论 "湾征"可作为关节镜下膝内侧副韧带断裂的诊断指征,以及术中韧带修复重建成功与否的判断依据。     

Healing and repair of ligament injuries in the knee

Although methods of treating ligamentous injuries have continually improved, many questions remain about enhancing the rate, quality, and completeness of ligament healing. It is known that the ability of a torn ligament to heal depends on a variety of factors, including anatomic location, presence of associated injuries, and selected treatment modality. A grade III injury of the medial collateral ligament (MCL) of the knee usually heals spontaneously. Surgical repair followed by immobilization of an isolated MCL tear does not enhance the healing process. In contrast, tears of the anterior cruciate ligament (ACL) and the posterior cruciate ligament often require surgical reconstruction. The MCL component of a combined ACL-MCL injury has a worse prognosis than an isolated MCL injury. The results of animal studies suggest that nonoperative treatment of an MCL injury is effective if combined with operative reconstruction of the ACL. Experimentation using animal models has helped to define the effects of ligament location, associated injuries, intrinsic factors, surgical repair, reconstruction, and exercise on ligament healing. New techniques utilizing growth factors and cell and gene therapies may offer the potential to enhance the rate and quality of healing of ligaments of the knee, as well as other ligaments in the body.     

前交叉韧带损伤对膝关节侧副韧带影响的运动还原在体稳定性研究

目的 对前交叉韧带(ACL)损伤膝关节侧副韧带长度变化进行运动还原在体稳定性研究.方法 2008年1月至6月收治8例单侧膝关节ACL断裂而对侧膝关节止常的患者,男6例,女2例;平均年龄25.3岁;在生理负重膝关节屈曲0°、15°、30°、60°和90°时采集相互垂直的二维(2D)图像,与三维CT(3D)图像在虚拟X线投射系统进行2D/3D图像配准,还原膝关节不同角度时股骨和胫骨的相对三维位置关系,并通过韧带止点还原的方法对内侧副韧带(MCL)、外侧副韧带(LCL)进行韧带长度分析,对比两侧膝关节侧副韧带的长度差异.结果 ACL损伤后在0°、15°和30°患膝MCL长度分别为(40.16±1.63)、(39.11±1.77)、(37.86±1.84)mm,健膝分别为(38.17±1.40)、(37.63±1.37)、(36.60±1.86)mm,健、患膝比较差异均有统计学意义(P<0.05);ACL损伤后在0°、15°和30°患膝LCL长度分别为(50.23±1.18)、(50.30±1.68)、(49.26±1.67)mm,健膝分别为(52.56±1.64)、(52.30±1.48)、(51.83±1.77)mm,健、患膝比较差异均有统计学意义(P<0.05).ACL损伤后60°和90°健、患膝MCL、LCL长度差异均无统计学意义(P>0.05).结论 通过2D/3D图像配准技术可以实现膝火节的运动还原并获得ACL损伤后生理屈曲过程中MCL和LCL的长度变化规律.在0°、15°和30°,ACL损伤后患膝MCL长度较健膝增加,而LCL长度较健膝缩短.     

膝关节多韧带损伤的临床研究

目的探讨膝关节多韧带损伤的诊断与治疗方法并评价其治疗效果。方法治疗51例单侧膝关节多韧带损伤,其损伤类型：21例前交叉韧带（ACL）＋内侧副韧带（MCL）,1例ACL＋后外侧复合体（PLC）,4例后交叉韧带（PCL）＋MCL,6例PCL＋PLC,6例ACL＋PCL＋MCL,3例ACL＋PCL＋PLC,8例ACL＋PCL,2例PCL＋髌腱。14例急性Ⅲ度MCL和3例急性Ⅲ度PLC损伤行切开手术,原位缝合,外固定制动3周,再行关节镜下其他韧带手术。2例Ⅲ度慢性MCL和3例Ⅲ度慢性PLC损伤行切开韧带重建术,并同期行关节镜下ACL或PCL重建术。在总共39条ACL损伤中,20条行关节镜下自体Hamstring腱ACL重建术,17条行关节镜下自体骨-髌腱-骨（BPB）重建ACL术,2条行同种异体肌腱重建ACL;在总共29条PCL损伤中,19条行关节镜下自体Hamstring腱PCL重建术,2条行同种异体肌腱重建PCL,另8条急性损伤经固定后由Ⅲ度变为〈Ⅱ度损伤,故未特别治疗。其中,17例ACL＋PCL损伤处理方法为：4例先行PCL重建,二期再行ACL的重建,7例同期自体Hamstring腱重建PCL、自体BPB重建ACL,2例为同种异体肌腱同期重建ACL和PCL,4例仅做ACL重建术。1例髌腱完全性断裂原位修复,另1例部分性髌腱损伤者未治疗。4例合并腓总神经损伤均未做特别治疗。结果平均随访2.4年（9个月～5年）。术后Lysholm评分平均为86.3（51～100）,Tegner活 动评分为5.2（2～8）,均较术前显著增加（P〈0.001）。1例外翻试验为2＋,2例Lachman试验或轴移试验≥2＋,6例应力后沉征或后抽屉试验2＋,4例内翻试验或反轴移试验2＋。其余的对应各种体格检查均为≤1＋。4例合并腓总神经损伤者,术后3例自行恢复,1例未恢复。结论在多韧带损伤中,≤Ⅱ度的MCL或者PLC损伤应采用保守治疗,Ⅲ度损伤者应尽早手术原位修复内侧副韧带及其关节囊或PLC,以利于后期进行其他重要韧带的治疗。交叉韧带或关节内重要组织可二期在?     

Medial collateral ligament avulsion from both tibial and femoral attachments: a case report

The medial collateral ligament (MCL) is the most commonly injured ligament of the knee joint. Proximal MCL tears occur more frequently than do distal ones. We report a 28-year-old man with a valgus injury of his left knee joint after a fall from a motorcycle. Magnetic resonance imaging of the affected knee joint revealed complete avulsion of the superficial MCL from both its femoral and tibial insertions. The meniscofemoral portion of the deep part of the MCL was also torn and the medial meniscus was subluxated. Such a pattern, an MCL tear with subluxation of the medial meniscus, is rare.     

膝前、后交叉韧带与内侧副韧带损伤的一期修复重建

目的探讨膝关节镜下重建前、后交叉韧带联合有限切开修复内侧副韧带恢复膝关节稳定和功能的疗效。方法 2003年4月-2010年10月,收治14例(14膝)前、后交叉韧带伴内侧副韧带损伤患者。男10例,女4例;年龄21～71岁,平均41岁。致伤原因:交通事故伤11例,高处坠落伤3例。患者受伤至入院时间为1～4 d,平均2 d。Lysholm评分为(17.00±8.29)分,国际膝关节文献委员会(IKDC)评分为(20.93±8.28)分。伴膝关节脱位9例,半月板损伤5例。关节镜下采用同种异体肌腱(2例)或自体腘绳肌腱(12例)重建前、后交叉韧带,有限切开修复内侧副韧带。结果术后切口均Ⅰ期愈合;3例出现下肢麻木,自行缓解。患者均获随访,随访时间为12～18个月,平均14个月。患者膝关节均于3个月内达屈曲120°,伸直0°。术后1年膝关节IKDC评分为(89.93±6.26)分,Lysholm评分为(88.93±4.82)分,与术前比较差异有统计学意义(P<0.01)。结论对于膝关节韧带多发伤,关节镜配合有限切开修复重建韧带,避免了开放关节腔,同时由于创伤小,术后关节粘连轻,关节功能恢复快。     

An anterior cruciate ligament and medial collateral ligament tear in a skeletally immature patient: a new technique to augment primary repair of the medial collateral ligament and an allograft reconstruction of the anterior cruciate ligament

The goal of this case report is to fill a dual purpose. We describe a case involving a tear of the anterior cruciate ligament (ACL) and medial collateral ligament (MCL) in a skeletally immature athlete. At the same time, we describe a new technique with which we repaired the ACL with an allograft posterior tibialis tendon through intra-articular tunnels. A trial of conservative therapy for the MCL was performed. During surgery, its instability was assessed. No improvement was seen in stability, so a primary repair of the MCL was performed and augmented with an autograft gracilis tendon. The patient did well postoperatively, subsequently achieving equal stability and range of motion when compared with the opposite limb. He was back to competitive sports at 6 months.     

Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament

This study tested the hypothesis that application of a valgus force necessary to create a complete medial collateral ligament (MCL) injury causes damage to the anterior cruciate ligament (ACL). Twelve cadaveric knees were used to measure concomitant loading and damage to the ACL in valgus knee loading sufficient to cause a grade III MCL injury. Displacement sensors were placed on the anteromedial bundle of the ACL and posterior oblique ligament to monitor tensile strain during creation of the MCL injury. A valgus moment was applied to knees flexed at 30 degrees, displacing the joint into valgus rotation beyond MCL rupture. Following valgus loading and MCL injury, femur-ACL-tibia specimens were tested to failure to compare ACL mechanical integrity to noninjured control specimens. Average ACL strength in MCL ruptured knees (1250 +/- 90 N) was statistically lower (P < or = .05) than that for control knees (2110 +/- 50 N). Strain measurements exhibited concomitant posterior oblique ligament strain during valgus loading, whereas ACL strain increased substantially only after MCL rupture. These data indicate that the ACL can be compromised in isolated grade III MCL injuries.     

Clinical outcome of primary medial collateral ligament-posteromedial corner repair with or without staged anterior cruciate ligament reconstruction

IntroductionMedial collateral ligament (MCL) is a prime valgus stabilizer of the knee, and MCL tears are currently managed conservatively. However, posteromedial corner (PMC) injury along with MCL tear is not same as isolated MCL tear and the former is more serious injury and requires operative attention. However, literature is scarce about the management and outcome of PMC-MCL tear alongside anterior cruciate ligament (ACL) tear. The purpose of this study is to report the clinical outcome of primary repair of MCL and PMC with or without staged ACL reconstruction.MethodsA retrospective evaluation was performed on patients with MCL-PMC complex injury with ACL tear who underwent primary repair of MCL-PMC tear followed by rehabilitation. Further, several of them chose to undergo ACL reconstruction whereas rest opted conservative treatment for the ACL tear. A total of 35 patients of two groups [Group 1 (n = 15): MCL-PMC repaired and ACL conserved; Group 2 (n = 20): MCL-PMC repaired and ACL reconstructed] met the inclusion criteria with a minimum follow-up of two years. Clinical outcome measures included grade of valgus medial opening (0° extension and 30° flexion), Lysholm and International knee documentation committee (IKDC) scores, KT-1000 measurement, subjective feeling of instability, range of motion (ROM) assessment and complications.ResultsWhile comparing group 2 versus group 1, mean Lysholm (94.6 vs. 91.06; p = 0.017) and IKDC scores (86.3 vs. 77.6; p = 0.011) of group 2 were significantly higher than group 1. 60% patients of group 1 complained of instability against none in the group 2 (p < 0.0001). All the knees of both the groups were valgus stable with none requiring late reconstruction. The mean loss of flexion ROM in group 1 and 2 was 12° and 9° respectively which was not statistically different (p = 0.41). However while considering the loss of motion, two groups did not show any significant difference in clinical scores.ConclusionsPrimary MCL-PMC repair renders the knee stable in coronal plane in both the groups and further ACL reconstruction adds on to the stability of the knee providing a superior clinical outcome. Minor knee stiffness remains a concern after primary MCL-PMC repair but without any unfavorable clinical effect.     

The healing medial collateral ligament following a combined anterior cruciate and medial collateral ligament injury--a biomechanical study in a goat model.

The ideal treatment of a combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injury to the knee is still debated. In particular, the question of whether reconstruction of the ACL can provide the knee with sufficient multidirectional stability to allow for effective MCL healing needs to be better elucidated. Therefore, the first objective of this study was to quantify the changes in the function of goat knees between time-zero and 6 weeks following a combined ACL/MCL injury treated with ACL reconstruction. Using a robotic/universal force-moment sensor testing system, the kinematics of the knee and in situ forces in the ACL/ACL graft as well as in the sham-operated and healing MCL were evaluated in response to (1) a 67 N anterior-posterior (A-P) tibial load and (2) a 5 Nm varus-valgus (V-V) moment. The second objective was to evaluate the structural properties of the healing femur-MCL-tibia complex (FMTC) and the mechanical properties of the healing MCL at 6 weeks under uniaxial tension.In response to the 67 N A-P tibial load, the A-P translations for the experimental knee increased by as much as 4.5 times from time-zero to 6 weeks (p<0.05). Correspondingly, the in situ forces in the ACL graft decreased by as much as 45% (p<0.05). There was no measurable changes of the in situ force in the healing MCL. In response to a 5 Nm V-V moment, V-V rotations were twice as much as controls, but similar for both time periods. From time-zero to 6 weeks, the in situ forces in the ACL graft dropped by over 71% (p<0.05), while the in situ force in the healing MCL was as much as 35+/-19 N.In terms of the structural properties of the healing FMTC, the stiffness and ultimate load values at 6 weeks reached 53% and 29% of sham-operated contralateral controls, respectively (p<0.05). For the mechanical properties of the healing MCL substance, the values for tangent modulus and tensile strength were only 13% and 10% of sham-operated controls, respectively (p<0.05). These results suggest that the ACL graft stabilized the knee initially, but became loose over time. As a result, the healing MCL may have been required to take on excessive loads and was unable to heal sufficiently as compared to an isolated MCL injury.     

In-vitro ligament tension pattern in the flexed knee in passive loading

Tensions generated in selected bands of the four major ligaments of the flexed knee (40-90 degrees) have been measured in vitro when the tibia is subjected to passive anterior translation and axial rotation with and without a compressive preload. The measurements were made in 30 fresh-frozen specimens using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibres of the posterior cruciate ligament [PCL (pf)], the superficial fibres of the medial collateral ligament [MCL (sf)], and in the total lateral collateral ligament (LCL). Particular attention was placed on the evaluation of the performance of the transducer specific to such measurements in order to minimize the errors associated with the use of this transducer. The results indicate that, among the measured ligaments, substantial tension (greater than 20 N) is generated only in the ACL (am) in tibial anterior translation up to 5 mm. The tension pattern generated in response to tibial axial rotation, however, is complex and exhibits considerable variation between specimens. In general, both the MCL (sf) and LCL are tensed at all tested flexion angles, with the tension in external rotation being significantly greater than in internal rotation. At 40 degrees of flexion, the ACL (am) bears tension mainly in internal rotation, while at 90 degrees of flexion the PCL (pf) is tensed in both senses of rotation. The response of the LCL shows marked variation among specimens; very small tension (less than 15 N) is generated in internal rotation in 48% of the specimens, and in either sense of rotation in 20% of the specimens. The tension in the ACL (am) in internal rotation is invariably greater in those specimens in which LCL tension is negligible. This correlation between increased ACL (am) function and inadequate LCL restraint appears significant in terms of ACL injury and repair.     

Simultaneous reconstruction of anterior cruciate ligament and posterior cruciate ligament by using allogeneic patellar tendon under arthroscopy

With fast development of arthroscopic surgery inChina, simple reconstruction of ACL (anteriorcrucial ligament) or PCL has been reported in number. However , the methods concerningsimultaneous reconstruction of ACL and PCL are rarelyreported. Simultaneous …     

Anterolateral ligament injuries on magnetic resonance imaging and pivot-shift testing for rotational laxity

Maintaining anterolateral rotational stability of the knee requires a complex set of structures, most notably the anterior cruciate ligament. However, lateral knee structures such as the anterolateral ligament (ALL) also play an important role. There has been controversy over the role the ALL plays in an ACL deficient knee to maintain rotational stability. In this study, we examined ACL deficient knees with and without intact ALLs, for rotatory laxity using a pivot shift examination. This was graded using International Knee Document Committee (IKDC) criteria. MRI was used to view the ALL and its status. We found no statistically significant difference in rotational stability of ACL deficient knees, with or without intact ALLs. We did however find a statistically significant association between injury to the ALL and other concomitant lateral structures such as the lateral collateral ligament, biceps femoris tendon, and iliotibial band. This supports that the ALL works in concert with the other lateral structures in the knee and the ACL, to provide rotational stability. This suggests that as an isolated structure, the ALL’s contribution to clinical rotational stability is not significant, even in the presence of an ACL tear.     

Correlation of healing capacity with vascular response in the anterior cruciate and medial collateral ligaments of the rabbit.

In clinical terms, functional recovery after anterior cruciate ligament (ACL) injury is generally poorer than after medial collateral ligament (MCL) injury. In experimental studies of injury, the early phases of ligament healing require an augmented blood supply. We hypothesized that the differences in healing properties of the ACL and MCL would be reflected in the magnitude of their vascular responses to partial injury. This study is the first to quantify and define the time course of changes in blood flow and vascular volume following hemisection of the rabbit ACL and MCL.Adult female rabbits were assigned to control, sham operation, ACL hemisection or MCL hemisection groups. Standardized ACL or MCL injuries were surgically induced. About 2, 6 or 16 weeks later, blood flow and vascular volume of the ACL and MCL were measured.The MCL of the rabbit responded to hemisection with a large significant increase in blood flow and a substantial angiogenic response associated with inflammation and scar formation. During subsequent matrix remodelling, blood flow and vascular volume returned towards control values. In contrast, the ACL showed only a 2-fold increase in vascular volume, no increase in blood flow and atrophied after hemisection. The superior capacity of the MCL to increase its blood supply through angiogenesis and increased flow is essential for ligament healing to occur, and may be the major difference in healing potential between the ACL and MCL.     

Periarticular ligament changes following ACL/MCL transection in an ovine stifle joint model of osteoarthritis.

Anterior cruciate ligament (ACL) injuries often lead to significant functional impairment, and are associated with increased risk for induction of degenerative joint disease. However, few studies have described the effect of ligament transection on the remaining intact knee ligaments. This study sought to determine specifically what impact combined ACL/medial collateral ligament (MCL) transection had on the remaining intact knee ligaments, particularly from the histological, biochemical, and molecular perspectives. Twenty weeks post-ACL/MCL transection, the cut ends of sheep MCLs were bridged by scar, while the posterior cruciate ligaments (PCLs) and lateral collateral ligaments (LCLs) seemed gross morphologically normal. Water content and cell density increased significantly in the MCL scars and the intact PCLs but were unchanged in the LCLs. Collagen fibril diameter distribution was significantly altered in both MCL scar tissue and uninjured PCLs from transected joints. MMP-13 mRNA levels in MCL scars and PCLs from ligament transected joints were increased, while TIMP-1 mRNA levels were significantly decreased in the PCLs only. This study has shown that some intact ligaments in injured joints are impacted by the injury. The joint appears to behave like an integrated organ system, with injury to one component affecting the other components as the "organ" attempts to adapt to the loss of integrity.     

What is the terrible triad?

In 1936 Campbell asserted that "impairment of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage." O'Donoghue in 1950 called attention to "that unhappy triad (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus, and (3) rupture of the anterior cruciate ligament" and recommended early surgical intervention. In 1955 he reported 33 cases with both medial collateral (MCL) and anterior cruciate ligament (ACL) tears, but there were only three lateral meniscus tears reported. Based on a recent report by Shelbourne and Nitz that questions the validity of this unhappy triad, a review of all arthroscopically confirmed acute injuries of second degree or worse to the ACL and MCL was undertaken. Of a total of 52 knees reviewed, 50 knees had third-degree ACL tears and two had second-degree ACL tears. One of the second-degree tears was associated with a second-degree MCL and one with a third-degree ACL tear. Neither had an associated meniscus tear. Forty-five third-degree ACL tears were associated with third-degree MCL tears (group 1) and five with second-degree MCL tears (group 2). Eighty percent (36 knees) of group 1 had lateral meniscus tears. Only 29% of group 1 (13 knees) had associated medial meniscus tears. None of these medial meniscus tears was isolated. Eighty percent (four knees) of group 2 had lateral meniscus tears with only one associated medial meniscus tear. Again, there were no medial meniscus tears in the absence of a lateral meniscus tear. We did not find the combination of injury originally described as the unhappy triad.     

Factors for the presence of anteromedial rotatory instability of the knee

Anteromedial rotatory instability (AMRI) of the knee joint was investigated with an instrument newly designed to simulate the manual AMRI test and to quantify its magnitude. Thirty healthy subjects, 20 patients with anterior cruciate ligament (ACL) injury, and 10 with both ACL and medial collateral ligament (MCL) injuries were examined. Using the instrument, 100N of anterior force was applied to the proximal part of the tibia with the foot in neutral rotation, 30° of internal rotation, and 30° of external rotation, and the magnitude of anterior displacement was recorded. The measurement was carried out at 20° and 90° of flexion. A significant increase in anterior laxity was observed in all three rotation positions in the injured patients. However, the magnitude of laxity in external rotation was less than that in neutral rotation in the ACL injured patients, whereas it was the greatest in external rotation in ACL + MCL injured patients. Thus, we conclude that an injury involving both the ACL and MCL causes AMRI.     

急诊关节镜下清创复位联合二期韧带重建治疗急性膝关节后外侧旋转脱位

目的总结急诊关节镜下复位清创联合二期韧带重建手术在急性膝关节后外侧旋转脱位治疗中的效果。方法回顾性分析2007年9月至2008年8月第三军医大学西南医院收治的3例急性膝关节后外侧旋转脱位患者的临床资料,3例患者均急诊行关节镜手术清创＋复位治疗,其中1例内侧副韧带（MCL）Ⅲ度损伤患者行MCL修补缝合术;2例MCLⅡ度损伤患者佩戴铰链支具保守治疗。术后3个月,3例患者接受LARS人工韧带前交叉韧带（ACL）重建术。观察患者膝关节活动度和Lysholm评分结果。结果平均随访15个月。3例患者均未出现膝关节前向不稳,前抽屉试验、轴移试验阴性;均未发生关节内异位骨化等病变。术后3个月,3例患者的膝关节活动度分别为0°～130°、0°～120°、0°～130°;重建术后12个月,3例患者的Lysholm评分分别为91、88、94分。结论急诊关节镜下复位、关节腔清理术结合标准化的ACL重建术对于膝关节后外侧旋转脱位的治疗效果较好。     

Vascular structure and function in the medial collateral ligament of anterior cruciate ligament transected rabbit knees

To determine if decreased vascular responsiveness in the medial collateral ligament (MCL) of anterior cruciate ligament transected (ACL‐t) rabbit knees is due to pericyte deficiency associated with angiogenesis. Vascular responses to potassium chloride (KCl), phenylephrine, acetylcholine, and sodium nitroprusside (SNP) were evaluated in ACL‐t rabbit knees (n = 6) and control knees (n = 5) using laser speckle perfusion imaging. Ligament degeneration was determined by ultrasound imaging. Vascular and pericyte volume were measured using quantitative immunohistochemical volumetric analysis using CD31 and α‐smooth muscle actin antibodies with co‐localization analysis. Perfusion was increased in the ACL‐t rabbits 2.5‐fold. Responsiveness to phenylephrine, SNP, and acetylcholine was significantly decreased in the ACL knee while no change in KCl responses was seen. MCL ultrasound imaging revealed decreased collagen organization, increased ligament thickness, and increased water content in the ACL‐t MCL. Vascular Volume was increased fourfold in ACL deficient knees, while pericyte volume to endothelial volume was not changed. No difference in CD31 and α‐SMA co‐localization was found. Blood vessels in the MCL of ACL‐t knees do not lack smooth muscle. The MCL vasculature can undergo constrictive response to KCl, but have impaired receptor mediated responses and impaired nitric oxide signaling. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1104–1110, 2014.     

Vascular physiology and long-term healing of partial ligament tears.

Functional outcomes of anterior cruciate ligament (ACL) injury are generally poorer than those of medial collateral ligament (MCL) tears. Following ligament damage, all phases of ligament healing require an adequate blood supply. We hypothesized that the differences in healing properties of the ACL and MCL would reflect their vascular responses to joint injury. This paper examines the long-term changes in blood flow and vascular volume of rabbit knee ligaments after direct injury, and under conditions of chronic joint instability induced by section of the posterior cruciate ligament (PCL). Standardized injuries were surgically induced in adult rabbit knee ligaments: partial MCL transection, partial ACL transection, or complete PCL transection (joint instability). Sixteen weeks later the blood flow and vascular volume of the ACL and MCL were measured and compared to control and sham-operated animals. Direct ligament injury induced significant increases in standardized blood flow and vascular volume of both ACL and MCL after 16 weeks; however, the vascular volume of the ACL was not higher than the control levels in the MCL. We conclude that direct injury to both the anterior cruciate and MCLs induces long-term physiological responses. Joint laxity is a common sequel to PCL injury. Chronic joint laxity failed to induce adaptive vascular responses in the ACL, while the MCL shows significant amplification of blood supply. Although both MCL and ACL showed increased weight after PCL transection, the lack of a long-term vascular response in the ACL may be a major factor in its the diminished healing potential.