Medial collateral ligament insertion site and contact forces in the ACL-deficient knee.

The objectives of this research were to determine the effects of anterior cruciate ligament (ACL) deficiency on medial collateral ligament (MCL) insertion site and contact forces during anterior tibial loading and valgus loading using a combined experimental-finite element (FE) approach. Our hypothesis was that ACL deficiency would increase MCL insertion site forces at the attachments to the tibia and femur and increase contact forces between the MCL and these bones. Six male knees were subjected to varus-valgus and anterior-posterior loading at flexion angles of 0 degrees and 30 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to establish a stress-free reference configuration. An FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus rotation and anterior translation at 0 degrees and 30 degrees, using subject-specific bone and ligament geometry and joint kinematics. A transversely isotropic hyperelastic material model with average material coefficients taken from a previous study was used to represent the MCL. Subject-specific MCL in situ strain distributions were used in each model. Insertion site and contact forces were determined from the FE analyses. FE predictions were validated by comparing MCL fiber strains to experimental measurements. The subject-specific FE predictions of MCL fiber stretch correlated well with the experimentally measured values (R2 = 0.95). ACL deficiency caused a significant increase in MCL insertion site and contact forces in response to anterior tibial loading. In contrast, ACL deficiency did not significantly increase MCL insertion site and contact forces in response to valgus loading, demonstrating that the ACL is not a restraint to valgus rotation in knees that have an intact MCL. When evaluating valgus laxity in the ACL-deficient knee, increased valgus laxity indicates a compromised MCL.     

Combined anterior cruciate ligament and medial collateral ligament injuries in adolescents

Although literature supports bracing of most medial collateral ligament (MCL) injuries followed by arthroscopic repair of anterior cruciate ligament (ACL) tears in adults with combined ACL-MCL injuries, little is published regarding the treatment of these injuries in the pediatric population. The purpose of this study was to present our outcomes after treatment of combined ACL-MCL injuries in a series of adolescents. All 180 patients who underwent ACL reconstruction at our children's hospital from January 1997 to January 2003 were reviewed to identify those patients with concomitant grade II or III MCL injuries. Clinical data were obtained from chart review. All patients were treated with a hinged brace for their MCL injury followed by delayed arthroscopic reconstruction of their ACL using a transphyseal technique with Achilles tendon soft tissue allograft. Patients were contacted by phone to complete Lysholm knee questionnaires and assess return to athletic competition. Data were compared with a control cohort of patients who underwent isolated ACL reconstruction using the same technique. Twelve (6.7%) of 180 patients had combined ACL-MCL injuries. There were 6 boys and 6 girls; the mean age was 15.6 years (range, 14-17 years). Follow-up averaged 5.3 years (range, 2.6-8.2 years), and no patients were lost to follow-up. At last examination, all patients had a stable knee on both Lachman and valgus stress tests; the mean Lysholm knee score was 96 (range, 94-100). All patients were able to return to their preinjury level of athletics. One patient required manipulation for arthrofibrosis. When compared with the control group of 19 isolated ACL reconstructions, there was no significant difference with regards to Lysholm scores or return to athletics.Bracing of grade 2 or 3 MCL injuries followed by ACL reconstruction was an effective means of treating combined ACL-MCL injuries in this small series of adolescent patients.     

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。     

Subject-specific finite element analysis of the human medial collateral ligament during valgus knee loading.

The objectives of this study were (1) to develop subject-specific experimental and finite element (FE) techniques to study the three-dimensional stress-strain behavior of ligaments, with application to the human medial collateral ligament (MCL), and (2) to determine the importance of subject-specific material properties and initial (in situ) strain distribution for prediction of the strain distribution in the MCL under valgus loading. Eight male knees were subjected to varus-valgus loading at flexion angles of 0 degrees, 30 degrees, and 60 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to allow measurement of the in situ strain distribution and to perform material testing. A FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus loading at each flexion angle, using subject-specific bone and ligament geometry, material properties, and joint kinematics. A transversely isotropic hyperelastic material model was used to represent the MCL. The MCL in situ strain distribution at full extension was used to apply in situ strain to each MCL FE model. FE predicted MCL strains during valgus loading were compared to experimental measurements using regression analysis. The subject-specific FE predictions of strain correlated reasonably well with experimentally measured MCL strains (R(2)=0.83, 0.72, and 0.66 at 0 degrees, 30 degrees, and 60 degrees, respectively). Despite large inter-subject variation in MCL material properties, MCL strain distributions predicted by individual FE models that used average MCL material properties were strongly correlated with subject-specific FE strain predictions (R(2)=0.99 at all flexion angles). However, predictions by FE models that used average in situ strain distributions yielded relatively poor correlations with subject-specific FE predictions (R(2)=0.44, 0.35, and 0.33 at flexion angles of 0 degrees, 30 degrees, and 60 degrees, respectively). The strain distribution within the MCL was nonuniform and changed with flexion angle. The highest MCL strains occurred at full extension in the posterior region of the MCL proximal to the joint line during valgus loading, suggesting this region may be most vulnerable to injury under these loading conditions. This work demonstrates that subject-specific FE models can predict the complex, nonuniform strain fields that occur in ligaments due to external loading of the joint.     

Roles of the anterior cruciate ligament and the medial collateral ligament in preventing valgus instability

Both the medial collateral ligament (MCL) and the anterior cruciate ligament (ACL) are reported to prevent valgus instability of the knee. In this study, the anatomical mechanisms by which these ligaments prevent valgus instability were experimentally investigated. The valgus rotation angle and the magnitude of the medial joint space opening were measured in six cadaveric knees, using biplanar photography before and after the MCL and/or the ACL were severed. A significant increase in the valgus rotation angle and a large medial joint space opening were observed when the MCL was severed. An increase in the valgus rotation angle was also observed when the ACL was severed, but only a small medial joint space opening was present. The increase in the valgus rotation angle after ACL severance was nearly parallel to the increase in the internal rotation of the tibia. Thus, we concluded that both ligaments function to prevent valgus instability, but that the anatomical reasons for their function are different. The MCL prevents valgus instability by stopping an opening in the medial joint space. The ACL, on the other hand, prevents the internal rotation of the tibia. When the ACL is severed, the internal rotation increases, and causes the valgus rotation angle to also increase, despite the presence of only a small medial joint space opening. Received: May 16, 2000 / Accepted: August 3, 2000     

Interaction between the ACL graft and MCL in a combined ACL+MCL knee injury using a goat model

The optimal treatment for the MCL in the combined ACL and MCL-injured knee is still controversial. Therefore, we designed this study to examine the mechanical interaction between the ACL graft and the MCL in a goat model using a robotic/universal force-moment sensor testing system. The kinematics of intact, ACL-deficient, ACL-reconstructed, and ACL-reconstructed/ MCL-deficient knees, as well as the in situ forces in the ACL, ACL graft, and MCL were determined in response to two external loading conditions: 1) anterior tibial load of 67 N and 2) valgus moment of 5 N-m. With an anterior tibial load, anterior tibial translation in the ACL-deficient knee significantly increased from 2.0 and 2.2 mm to 15.7 and 18.1 mm at 30 degrees and 60 degrees of knee flexion, respectively. The in situ forces in the MCL also increased from 8 to 27 N at 60 degrees of knee flexion. ACL reconstruction reduced the anterior tibial translation to within 2 mm of the intact knee and significantly reduced the in situ force in the MCL to 17 N. However, in response to a valgus moment, the in situ forces in the ACL graft increased significantly by 34 N after transecting the MCL. These findings show that ACL deficiency can increase the in situ forces in the MCL while ACL reconstruction can reduce the in situ forces in the MCL in response to an anterior tibial load. On the other hand, the ACL graft is subjected to significantly higher in situ forces with MCL deficiency during an applied valgus moment. Therefore, the ACL-reconstructed knee with a combined ACL and MCL injury should be protected from high valgus moments during early healing to avoid excessive loading on the graft.     

Arthroscopically assisted combined anterior and posterior cruciate ligament reconstruction in the multiple ligament injured knee: 2- to 10-year follow-up

Purpose: This study presents the 2- to 10-year results of 35 arthroscopically assisted combined anterior cruciate ligament and posterior cruciate ligament (ACL/PCL) reconstructions evaluated preoperative and postoperatively using Lysholm, Tegner, and Hospital for Special Surgery knee ligament rating scales, KT-1000 arthrometer testing, stress radiography, and physical examination. Type of Study: Case series. Methods: This study population included 26 men and 9 women with 19 acute and 16 chronic knee injuries. Ligament injuries included 19 ACL/PCL/posterolateral instabilities, 9 ACL/PCL/medial cruciate ligament (MCL) instabilities, 6 ACL/PCL/posterolateral/MCL instabilities, and 1 ACL/PCL instability. All knees had grade III preoperative ACL/PCL laxity and were assessed preoperatively and postoperatively with arthrometer testing, 3 different knee ligament rating scales, stress radiography, and physical examination. Arthroscopically assisted combined ACL/PCL reconstructions were performed using the single-incision endoscopic ACL technique and the single femoral tunnel–single bundle transtibial tunnel PCL technique. PCLs were reconstructed with allograft Achilles tendon (in 26 cases), autograft bone–patellar tendon–bone (BPTB) (in 7 cases), and autograft semitendinosus/gracilis (in 2 cases). ACLs were reconstructed with autograft BPTB (16 cases), allograft BPTB (12 cases), Achilles tendon allograft (6 cases), and autograft semitendinosus/gracilis (1 case). MCL injuries were treated with bracing or open reconstruction. Posterolateral instability was treated with biceps femoris tendon transfer, with or without primary repair, and posterolateral capsular shift procedures as indicated. Results: Postoperative physical examination revealed normal posterior drawer/tibial step-off in 16 of 35 (46%) knees. Normal Lackman and pivot-shift test results were found in 33 of 35 (94%) knees. Posterolateral stability was restored to normal in 6 of 25 (24%) knees, and tighter than normal knee results were found in 19 of 25 (76%) knees evaluated with the external rotation thigh foot angle test. In this group, 30° varus stress testing was normal in 22 of 25 (88%) knees, and grade 1 laxity was found in 3 of 25 (12%) knees. 30° valgus stress testing was normal in 7 of 7 (100%) surgically treated MCL tears, and in 7 of 8 (87.5%) brace-treated knees. Postoperative KT-1000 arthrometer testing mean side-to-side difference measurements were 2.7 mm (PCL screen), 2.6 mm (corrected posterior), and 1.0 mm (corrected anterior) measurements, a statistically significant improvement from preoperative status (P = .001). Postoperative stress radiographic side-to-side difference measurements measured at 90° of knee flexion and 32 lb posteriorly directed proximal force were 0 to 3 mm in 11 of 21 (52.3%) knees, 4 to 5 mm in 5 of 21 (23.8%), and 6 to 10 mm in 4 of 21 (19%) knees. Postoperative Lysholm, Tegner, and HSS knee ligament rating scale mean values were 91.2, 5.3, and 86.8, respectively, showing a statistically significant improvement from preoperative status (P = .001). Conclusions: Combined ACL/PCL instabilities can be successfully treated with arthroscopic reconstruction and the appropriate collateral ligament surgery. Statistically significant improvement is noted from the preoperative condition at 2- to 10-year follow-up using objective parameters of knee ligament rating scales, arthrometer testing, stress radiography, and physical examination. Postoperatively, these knees are not normal, but they are functionally stable. Continuing technical improvements will probably improve future results.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 7 (September), 2002: pp 703–714     

Healing of the medial collateral ligament following a triad injury: a biomechanical and histological study of the knee in rabbits.

The effect of a partial medial meniscectomy and anterior cruciate ligament (ACL) transection on medial collateral ligament (MCL) healing was studied in skeletally mature rabbits. Two groups of animals, group I (isolated MCL rupture) and group II (MCL rupture with ACL transection and partial medial meniscectomy), were examined. At 6 and 12 weeks postoperatively, histological examination of the healing MCL and biomechanical evaluation of the varus-valgus (V-V) knee rotation and tensile properties of the femur-MCL-tibia complex (FMTC) were performed. Group II animals experienced substantial joint degeneration by 6 weeks. Progressive osteophyte formation was observed adjacent to the MCL insertions along with proximal migration of the MCL tibial insertion between 6 and 12 weeks. Histologic examination of the healing MCL substance from both groups showed disorganized collagen, inflammation, and fibroblast proliferation that decreased over time. For group II knees, the V-V knee rotation was found to be significantly elevated (4.7 to 5.2 times the contralateral control), and did not decrease with time. In contrast, the V-V knee rotations of the group I specimens were 1.8 times greater than control immediately following injury, and approached control values by 12 weeks. Tensile testing of the FMTCs revealed that the ultimate load increased with time for both groups, but group I had significantly higher values than group II. The linear stiffness in group I was not different than that group II and did not increase with time. For the mechanical (material) properties of the healed MCL substance, the modulus of the healing tissue for group II was only 40% that of group I. The structural properties of the FMTC and the mechanical properties of the MCL substance from both groups at 6 and 12 weeks were significantly different from the contralateral controls. We further demonstrated that immediately after ACL reconstruction, the V-V rotation of group II knees could be restored to group I levels. Recent clinical studies of MCL healing following isolated complete ligament tears have suggested that nonoperative management without immobilization leads to excellent treatment outcome. However, in more severe injuries involving additional tissues, poor quality of the healed ligament tissue and articular degeneration are observed. Our results demonstrate the deleterious effects of an untreated triad injury on the healing of the MCL substance and its insertions. Examination of the MCL substance suggests that a much larger healing mass is formed following a triad injury, which partially compensates for inferior ligament mechanical properties.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Instability of knees with ligament lesions. Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact. Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70-80 degrees, a sudden reduction was observed.     

Instability of knees with ligament lesions: Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact.

Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70–80 degrees, a sudden reduction was observed     

Instability of knees with ligament lesions: Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact.

Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70-80 degrees, a sudden reduction was observed     

The efficacy of magnetic resonance imaging in acute multi-ligament injuries

This study compares MRI with examination under anaesthesia to surgical findings in evaluating soft tissue injuries in acute multi-ligament knee trauma. Pre-operative MRI was done for 44 patients who underwent surgery for grade III ACL and grade III medial collateral ligament (MCL) injury. In 21 cases both ACL and MCL were treated surgically, but in 23 only ACL. Intra-operative and MRI findings were compared. Accuracy of MRI for medial meniscal tears was 88.6%, sensitivity 80%, and specificity 91.2%; accuracy for lateral meniscal tears was 72.7%, sensitivity 55% and specificity 87.5%. Accuracy and sensitivity for severity of ACL tear was 93.2% and of MCL tear 86.4%. In 88.6% of the knees, bone bruises were visible, with anterolateral femoral and posterolateral tibial bone bruise being the most common. MRI revealed no chondral lesion, but arthroscopy revealed 11. In combined ACL–MCL ruptures, the incidence of concomitant injuries is high and the injuries are best detected with MRI.     

Interaction between the ACL graft and MCL in a combined ACL+MCL knee injury using a goat model

The optimal treatment for the MCL in the combined ACL and MCL-injured knee is still controversial. Therefore, we designed this study to examine the mechanical interaction between the ACL graft and the MCL in a goat model using a robotic/universal force-moment sensor testing system. The kinematics of intact, ACL-deficient, ACL-reconstructed, and ACL-reconstructed/MCL-deficient knees, as well as the in situ forces in the ACL, ACL graft, and MCL were determined in response to two external loading conditions: 1) anterior tibial load of 67 N and 2) valgus moment of 5 N-m. With an anterior tibial load, anterior tibial translation in the ACL-deficient knee significantly increased from 2.0 and 2.2 mm to 15.7 and 18.1 mm at 30° and 60° of knee flexion, respectively. The in situ forces in the MCL also increased from 8 to 27 N at 60° of knee flexion. ACL reconstruction reduced the anterior tibial translation to within 2 mm of the intact knee and significantly reduced the in situ force in the MCL to 17 N. However, in response to a valgus moment, the in situ forces in the ACL graft increased significantly by 34 N after transecting the MCL. These findings show that ACL deficiency can increase the in situ forces in the MCL while ACL reconstruction can reduce the in situ forces in the MCL in response to an anterior tibial load. On the other hand, the ACL graft is subjected to significantly higher in situ forces with MCL deficiency during an applied valgus moment. Therefore, the ACL-reconstructed knee with a combined ACL and MCL injury should be protected from high valgus moments during early healing to avoid excessive loading on the graft.     

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.     

Interaction between the ACL graft and MCL in a combined ACL+MCL knee injury using a goat model

The optimal treatment for the MCL in the combined ACL and MCL-injured knee is still controversial. Therefore, we designed this study to examine the mechanical interaction between the ACL graft and the MCL in a goat model using a robotic/universal force-moment sensor testing system. The kinematics of intact, ACL-deficient, ACL-reconstructed, and ACL-reconstructed/MCL-deficient knees, as well as the in situ forces in the ACL, ACL graft, and MCL were determined in response to two external loading conditions: 1) anterior tibial load of 67 N and 2) valgus moment of 5 N-m. With an anterior tibial load, anterior tibial translation in the ACL-deficient knee significantly increased from 2.0 and 2.2 mm to 15.7 and 18.1 mm at 30° and 60° of knee flexion, respectively. The in situ forces in the MCL also increased from 8 to 27 N at 60° of knee flexion. ACL reconstruction reduced the anterior tibial translation to within 2 mm of the intact knee and significantly reduced the in situ force in the MCL to 17 N. However, in response to a valgus moment, the in situ forces in the ACL graft increased significantly by 34 N after transecting the MCL. These findings show that ACL deficiency can increase the in situ forces in the MCL while ACL reconstruction can reduce the in situ forces in the MCL in response to an anterior tibial load. On the other hand, the ACL graft is subjected to significantly higher in situ forces with MCL deficiency during an applied valgus moment. Therefore, the ACL-reconstructed knee with a combined ACL and MCL injury should be protected from high valgus moments during early healing to avoid excessive loading on the graft.     

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.     

Posttraumatic incarceration of medial collateral ligament into knee joint with anterior cruciate ligament injury

Medial collateral ligament of the knee is an important coronal stabiliser and often injured in isolation or as combination of injuries. The article reports a case of incarcerated medial collateral ligament (MCL) injury in combination with anterior cruciate ligament (ACL) injury in 20 year old male who presented to us 4 weeks after injury. Clinical examination and MRI was correlated to complete ACL tear with torn distal MCL and incarceration into the joint. Patient was taken up for ACL hamstring graft reconstruction with mini-arthrotomy and repair of the torn MCL. Patient was followed up with dedicated rehabilitation protocol with good functional results. At one year follow-up, patient exhibited full range of motion with negative Lachman, Pivot shift and valgus stress tests. This article highlights the rare pattern of MCL tear and also reviews the literature on this pattern of 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.     

The effect of medial collateral ligament insufficiency on the reconstructed anterior cruciate ligament: A study in the rabbit

The treatment for severe combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) ruptures is disputed. Using a rabbit model, we examined the effect of insufficiency of medial structures on the reconstructed ACL in combined ACL and MCL injury. 40 rabbits were divided into 2 groups. In both groups, ACL was subjected to in situ freezethaw treatment. In group F, only freeze-thaw treatment of ACL was given. In group FM, partial resection of MCL was also done. We killed 5 rabbits on each of 4 occasions: immediately after the operation (time 0), at 6, 12 and 24 weeks postoperatively. At each time, we measured valgus instability and mechanical properties of the ACL. Valgus instability in group FM persisted from time 0 to 24 weeks, and was significantly greater than that in group F. The tensile strength and tangent modulus of the ACL in group FM were lower than those in group F. We found that continuous valgus instability reduces the mechanical properties of the in situ frozen ACL.