The iliotibial band in acute knee trauma: patterns of injury on MR imaging

Demystifying the "Dark Side of the Knee": An Update on Imaging of the Posterolateral Corner

The posterolateral corner (PLC) of the knee is a complex anatomical-functional unit that includes ligamentous and tendinous structures that are crucial for joint stability. This review discusses the intricate anatomy, biomechanics, and imaging modalities, as well as the current challenges in diagnosing PLC injuries, with an emphasis on magnetic resonance imaging (MRI). Recognizing the normal MRI anatomy is critical in identifying abnormalities and guiding effective treatment strategies. Identification of the smaller structures of the PLC, traditionally difficult to depict on imaging, may not be necessary to diagnose a clinically significant PLC injury. Injuries to the PLC, often associated with cruciate ligament tears, should be promptly identified because failure to recognize them may result in persistent instability, secondary osteoarthritis, and cruciate graft failure.

The locked knee

The acute locked knee is an orthopaedic emergency requiring prompt diagnosis and treatment. It can be classified as acute or chronic. The term 'locked knee' refers to a knee that demonstrates fixed flexion or which has a 'block' to complete extension. Some degree of active or passive extension may be achievable, but not full extension. The most frequent causes of a locked knee are a meniscal tear, rupture of the anterior cruciate ligament or loose bodies. Magnetic resonance imaging is the gold standard in diagnostic imaging. Knee arthroscopy is considered the gold standard in management. This article gives an overview of the presentation, assessment and management of the locked knee for core surgical, acute care common stem and emergency medicine trainees.

The Anterolateral Ligament of the Knee in Pediatric Patients: What Do We Know? A Scoping Review

The knowledge on the anatomy, function and biomechanics and the role of surgical procedures on the anterolateral ligament (ALL) of the knee is still controversial. Only a few papers have examined the ALL in children. The aim of this review is to analyze all the available literature about ALL in the pediatric population. Following the PRISMA criteria, the literature was systematically reviewed, examining all the articles about ALL in pediatric patients. Eight articles were involved in this study. Five cadaveric studies, two diagnostic studies, and one cross-sectional study were found. The identification of the ALL is not always possible in diagnostic studies using magnetic resonance (MRI) or in dissecting specimens. A high variability in the presence of the ligament and in its origin and insertion were found among the studies. It is more difficult to identify the ligament in younger patients than in older children, suggesting that its presence may develop at some point during the growth. Further studies are needed for a detailed knowledge of the ALL.

Anterolateral complex of the knee: State of the art

Rotatory instability of the knee represents the main reason for failure and poor clinical outcomes regarding anterior cruciate ligament (ACL) reconstruction techniques. It is now clear that the anterolateral complex (ALC) of the knee possesses a fundamental role, in association with the ACL, in controlling internal rotation. Over the past decade, ever since the anterolateral ligament has been identified and described as a distinct structure, there has been a renewed interest in the scientific community about the whole ALC: Lateral extra-articular tenodesis have made a comeback in association with ACL reconstructions to improve functional outcomes, reducing the risks of graft failure and associated injuries. Modern ACL reconstruction surgery must therefore investigate residual instability and proceed, when necessary, to extra-articular techniques, whether functional tenodesis or anatomical reconstruction.This review aims to investigate the latest anatomical and histological descriptions, and the role in rotational control and knee biomechanics of the ALC and its components. The diagnostic tools for its identification, different reconstruction techniques, and possible surgical indications are described.. In addition, clinical and functional results available in the literature are reported.

Intraobserver Assessment of Shear Wave Elastography in Tensor Fasciae Latae and Gluteus Maximus Muscle: The Importance of the Hip Abductor Muscles in Runners Knee Compared to Healthy Controls

Background: Iliotibial band syndrome (ITBS) represents one of the most common running related injuries. The pathophysiology is postulated to be caused by excessive ITB tension, impingement and irritation of soft tissues at the lateral femoral epicondyle. However, direct evidence has yet to be found and the multifactorial etiology is under discussion. The purpose was to evaluate stiffness of ITB, gluteus maximus (GM) and tensor fasciae latae (TFL) muscles using shear wave elastography (SWE). Methods: In 14 patients with clinically verified ITBS and 14 healthy controls, three SWE measurements each of ITB, GM and TFL in both legs was performed to determine measurement reliability and between-group and -leg differences. Results: The mean value of ITB was 12.8 m/s with ICC of 0.76, whereas the values measured in the GM were 3.02 m/s with an ICC of 0.87. No statistically significant difference in controls compared to patients were found (p = 0.62). The mean value of TFL was 5.42 m/s in healthy participants, compared to 3.89 m/s patients with an ICC of 0.98 (p = 0.002). Conclusion: Although SWE showed no difference in ITB stiffness, significant differences for TFL muscle stiffness in runner’s knee was found, suggesting that the hip abductor muscles might play a bigger role in the pathophysiology of ITBS. We aimed to implement baseline values for stiffness assessments and prove reliability for further prospective studies of SWE in runner’s knee.

Isolated lateral extra-articular tenodesis enhance better rotatory knee joint stability post-primary ACL repair: Four cases report and literature review

INTRODUCTION AND IMPORTANCE

Residual rotatory instability has been reported to occur after primary anterior cruciate ligament reconstruction. The anterolateral ligament complex of the knee has gained attention for its role in rotational instability of the knee, especially in association with anterior cruciate ligament injuries. The role of an isolated lateral extra-articular tenodesis procedure among those patients presenting with residual rotatory instability after primary anterior cruciate ligament reconstruction has not been reported on.

CASE PRESENTATION

Four patients (Tegner level 4) presenting with residual rotatory instability after primary anterior cruciate ligament reconstruction without signs of graft failure, underwent an isolated lateral extra-articular tenodesis with modified Lemaire procedure. Pre- and postoperative outcome scores were assessed. At one-year follow-up, all patients reported functional knee stability. Pivot shift tests were negative and postoperative Lysholm scores were increased with a mean of 19.75 points. Tegner scores equaled the preinjury level.

CLINICAL DISCUSSION

This case report showed that our four patients where successfully treated with an isolated secondary modified Lemaire procedure for residual anterolateral rotatory instability after primary anterior cruciate ligament reconstruction.

CONCLUSION

An isolated secondary lateral extra-articular tenodesis procedure can be a valuable treatment option for moderate active patients with residual rotatory instability after a primary anterior cruciate ligament reconstruction without signs of graft failure.

The anterolateral ligament in acute knee trauma: patterns of injury on MR imaging

OBJECTIVE

To delineate the spectrum of traumatic knee injuries associated with injury of the anterolateral ligament of the knee (ALL).

MATERIALS AND METHODS

A retrospective review of 200 MRI scans undertaken for acute knee trauma was performed. In each scan, the ALL was scored as normal, sprained or torn. The menisci, ligaments and tendons of each knee were also assessed.

RESULTS

The mean age was 27.4 years (range, 9-69 years), and 71.5% (n = 143) of the patients were male. The anterolateral ligament (ALL) was graded as ruptured in 17 cases (8.5%), sprained in 58 cases (29%), normal in 116 cases (58%) and not visible in 9 cases (4.5%). Of cases with injury of the ALL (n = 75), there was associated injury of the anterior cruciate ligament (ACL) in 61 cases, medial collateral ligament (MCL) in 51 cases, popliteofibular ligament (PFL) in 29 cases, medial meniscus in 29 cases, lateral meniscus in 24 cases, lateral collateral ligament in 9 cases, posterior cruciate ligament in 8 cases, biceps femoris in 5 cases, popliteus tendon in 4 cases and fluid or oedema was seen adjacent to the iliotibial band in 59 cases. No cases of isolated ALL injury were seen.

CONCLUSIONS

ALL injury is not uncommon in acute knee trauma and is typically associated with significant internal derangement of the knee, especially anterior cruciate ligament rupture, ITB sprain, medial collateral ligament injury, meniscal tears and injury to the popliteofibular ligament.

The Incidence of Kaplan Fiber Injury Associated With Acute Anterior Cruciate Ligament Tear Based on Magnetic Resonance Imaging

BACKGROUND

Kaplan fibers are distinct deep layers of the distal iliotibial band (ITB) that anchor the ITB to the distal femur and have a role in rotational stability of the knee. However, the incidence of Kaplan fiber injury in the setting of acute anterior cruciate ligament (ACL) tear is unknown.

PURPOSE

To determine the reliability of identifying and evaluating Kaplan fibers on magnetic resonance imaging (MRI) examinations based on previously reported characteristics and to report on the incidence of combined ACL and Kaplan fiber injuries based on MRI examinations.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Patients with an acute primary ACL tear who obtained a postinjury MRI scan at our institution and were treated with ACL reconstruction between January 1, 2007, and May 31, 2012, were identified from an institutional registry. Each patient's postinjury MRI scan was reviewed by 2 musculoskeletal radiologists, who identified Kaplan fibers and graded them as intact, injured, or not visualized. Intrarater reliability was measured using the intraclass correlation coefficient (ICC), and interrater reliability was measured using the kappa statistic.

RESULTS

A total of 72 patients were identified. For the proximal Kaplan fibers, 50% versus 58% were identified as injured, 32% versus 29% were identified as intact, and 18% versus 13% were not visualized by radiologist 1 and 2, respectively. For the distal Kaplan fibers, 46% versus 60% were identified as injured, 43% versus 28% were identified as intact, and 11% versus 12% were not visualized by radiologist 1 and 2, respectively. The ICC intrarater reliability measurements were 0.89 (95% CI, 0.83-0.93) for proximal Kaplan fibers and 0.66 (95% CI, 0.51-0.78) for distal Kaplan fibers. The interrater reliability measurements for both radiologists showed substantial agreement (kappa = 0.7) for proximal Kaplan fibers and moderate agreement (kappa = 0.51) for distal Kaplan fibers.

CONCLUSION

Kaplan fibers were visualized on MRI studies in the majority of cases, with substantial reliability for the proximal fibers and moderate reliability for the distal fibers. There was an associated injury to either the proximal or distal or both Kaplan fibers in the majority of acute primary ACL tears.

Magnetic resonance imaging of the knee

Knee pain is frequently seen in patients of all ages, with a wide range of possible aetiologies. Magnetic resonance imaging (MRI) of the knee is a common diagnostic examination performed for detecting and characterising acute and chronic internal derangement injuries of the knee and helps guide patient management. This article reviews the current clinical practice of MRI evaluation and interpretation of meniscal, ligamentous, cartilaginous, and synovial disorders within the knee that are commonly encountered.

Magnetic resonance imaging of impingement and friction syndromes around the knee

The knee is a complex joint with its function dependent on a combination of osseous and soft tissue structures. Alteration in the relationship of these tissues, due to either acute or chronic repetitive injury with possible underlying congenital predisposing factors, can result in impingement between the structures resulting in pain, particularly on activity. The purpose of this article is to provide a comprehensive review of the MRI features of various impingement syndromes around the knee.

Incidence and Prognostic Significance of the Segond Fracture in Patients Undergoing Anterior Cruciate Ligament Reconstruction

BACKGROUND

The Segond fracture is an avulsion of the anterolateral tibia that can be found in patients with an anterior cruciate ligament (ACL) tear. It is currently unclear if the Segond fracture needs treatment or if it heals spontaneously and if it is associated with an increased risk of failure after ACL reconstruction.

PURPOSE

To identify the incidence and spontaneous healing rate of Segond fractures in a consecutive cohort of patients undergoing ACL reconstruction and to examine the predictive value of the Segond fracture on the risk of undergoing revision surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review of a cohort undergoing isolated ACL reconstruction between 2002 and 2016 was performed. Radiographs from the time of injury and preoperative radiographs were evaluated for Segond fractures and healed Segond fractures. Descriptive data were extracted from an internal quality database. Statistical analyses were performed to investigate risk of revision surgery and to compare across subgroups of patients.

RESULTS

A total of 1364 patients were included in the study. The incidence of Segond fractures was 7.4%. In addition, 10.4% of patients displayed signs of healed Segond fractures. In total, 15.2% of patients had either 1 or both findings. The overall healing response of the fracture was 35.6%. Those with Segond fractures were older (P = .014) and had a shorter interval from injury to surgery (P = .003) as compared with the rest of the cohort. The incidence of Segond fractures was significantly higher in those injured during downhill skiing as compared with other injury mechanisms (P = .04). The Segond fracture did not represent an increased risk of undergoing revision when compared with the control group (not significant).

CONCLUSION

The incidence of conventional Segond fractures in patients with ACL injury was found to be in accordance with former studies. Accounting for the high incidence of healed Segond fractures, a much higher incidence (15%) was seen. Although the spontaneous healing rate from initial radiographs to preoperative imaging was only 36%, the presence of Segond fractures did not represent a higher risk of undergoing revision surgery.

ACL reconstruction combined with lateral monoloop tenodesis can restore intact knee laxity

PURPOSE

An anterior cruciate ligament (ACL) injury is often combined with injury to the lateral extra-articular structures, which may cause a combined anterior and rotational laxity. It was hypothesised that addition of a 'monoloop' lateral extra-articular tenodesis (mLET) to an ACL reconstruction would restore anteroposterior, internal rotation and pivot-shift laxities better than isolated ACL reconstruction in combined injuries.

METHOD

Twelve cadaveric knees were tested, using an optical tracking system to record the kinematics through 0°-100° of knee flexion with no load, anterior and posterior translational forces (90 N), internal and external rotational torques (5 Nm), and a combination of an anterior translational (90 N) plus internal rotational load (5 Nm). They were tested intact, after sectioning the ACL, sectioning anterolateral ligament (ALL), iliotibial band (ITB) graft harvest, releasing deep ITB fibres, hamstrings tendon ACL reconstruction, mLET combined with ACL reconstruction, and isolated mLET. Two-way repeated-measures ANOVA compared laxity data across knee states and flexion angles. When differences were found, paired t tests with Bonferroni correction were performed.

RESULTS

In the ACL-deficient knee, cutting the ALL significantly increased anterior laxity only at 20°-30°, and only significantly increased internal rotation at 50°. Additional deep ITB release significantly increased anterior laxity at 40°-90° and caused a large increase of internal rotation at 20°-100°. Isolated ACL reconstruction restored anterior drawer, but significant differences remained in internal rotation at 30°-100°. After adding an mLET there were no remaining differences with anterior translation or internal rotation compared to the intact knee. With the combined injury, isolated mLET allowed abnormal anterior translation and rotation to persist.

CONCLUSIONS

Cutting the deep fibres of the ITB caused large increases in tibial internal rotation laxity across the range of knee flexion, while cutting the ALL alone did not. With ACL deficiency combined with anterolateral deficiency, ACL reconstruction alone was insufficient to restore native knee rotational laxity. However, combining a 'monoloop' lateral extra-articular tenodesis with ACL reconstruction did restore native knee laxity.

Biomechanical Assessment of a Distally Fixed Lateral Extra-articular Augmentation Procedure in the Treatment of Anterolateral Rotational Laxity of the Knee

BACKGROUND

Most lateral extra-articular tenodesis (LET) procedures rely on passing a strip of the iliotibial band (ITB) under the fibular (lateral) collateral ligament and fixing it proximally to the femur. The Ellison procedure is a distally fixed lateral extra-articular augmentation procedure with no proximal fixation of the ITB. It has the potential advantages of maintaining a dynamic element of control of knee rotation and avoiding the possibility of overconstraint.

HYPOTHESIS

The modified Ellison procedure would restore native knee kinematics after sectioning of the anterolateral capsule, and closure of the ITB defect would decrease rotational laxity of the knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve fresh-frozen cadaveric knees were tested in a 6 degrees of freedom robotic system through 0° to 90° of knee flexion to assess anteroposterior, internal rotation (IR), and external rotation laxities. A simulated pivot shift (SPS) was performed at 0°, 15°, 30°, and 45° of flexion. Kinematic testing was performed in the intact knee and anterolateral capsule-injured knee and after the modified Ellison procedure, with and without closure of the ITB defect. A novel pulley system was used to load the ITB at 30 N for all testing states. Statistical analysis used repeated measures analyses of variance and paired t tests with Bonferroni adjustments.

RESULTS

Sectioning of the anterolateral capsule increased anterior drawer and IR during isolated displacement and with the SPS (mean increase, 2° of IR; P < .05). The modified Ellison procedure reduced both isolated and coupled IR as compared with the sectioned state (P < .05). During isolated testing, IR was reduced close to that of the intact state with the modified Ellison procedure, except at 30° of knee flexion, when it was slightly overconstrained. During the SPS, IR with the closed modified Ellison was less than that in the intact state at 15° and 30° of flexion. No significant differences in knee kinematics were seen between the ITB defect open and closed.

CONCLUSION

A distally fixed lateral augmentation procedure can closely restore knee laxities to native values in an anterolateral capsule-sectioned knee. Although the modified Ellison did result in overconstraint to isolated IR and coupled IR during SPS, this occurred only in the early range of knee flexion. Closure of the ITB defect had no effect on knee kinematics.

CLINICAL RELEVANCE

A distally fixed lateral extra-articular augmentation procedure provides an alternative to a proximally fixed LET and can reduce anterolateral laxity in the anterolateral capsule-injured knee and restore kinematics close to the intact state.

High Prevalence of Anterolateral Ligament Abnormalities on MRI in Knees With Acute Anterior Cruciate Ligament Injuries: A Case-Control Series From the SANTI Study Group

Background:

Broad variation in the reported rate of magnetic resonance imaging (MRI)–detected abnormalities of the anterolateral structures of the anterior cruciate ligament (ACL)–injured knee suggests a lack of reliability that has limited the use of MRI in clinical decision making.

Purpose/Hypothesis:

The aim of this study was to use MRI to determine the prevalence and spectrum of abnormalities of the anterolateral structures in acute ACL-injured knees, using the contralateral uninjured knee as a reference. We hypothesized that MRI evaluation of the acutely injured knee (using the uninjured knee as a reference) would allow reliable identification of abnormalities of the anterolateral structures.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

Patients with acute ACL injury underwent MRI scan of both knees. Images were evaluated by 3 observers. Inter- and intraobserver reliabilities were determined for MRI parameters of anterolateral ligament (ALL) injury by use of the kappa (κ) test. Univariate and multivariate analyses were conducted to test associations between ALL abnormality and associated injuries.

Results:

A total of 34 patients were evaluated. Of these, 30 patients (88.2%) had at least 1 ALL abnormality in the ACL-injured knee (increased signal: n = 27[79.4%]; increased thickness: n = 15[44.1%]; tapering: n = 7[20.6%]; irregularities in the path of the ALL fibers: n = 21[61.7%]). Asymmetries of the genicular vessels were observed in 21 patients (61.7%). ALL abnormality was significantly associated with lateral joint capsular tears (P < .001). No correlation was found between ALL lesions and iliotibial band lesions (P = .49). Inter- and intraobserver reliabilities were very good concerning ALL signal changes and femoral and tibial bone bruises (κ coefficient, 0.81-1).

Conclusion:

MRI evaluation of the ALL was associated with good and very good inter- and intraobserver reliabilities, and it demonstrated abnormalities of the ALL in the majority of acutely ACL-injured knees. The index of suspicion for ALL injury should be elevated by the presence of lesions of the lateral capsule. This suggests that the ALL is part of a wider area of the lateral capsule that is often injured simultaneously in an acute ACL tear.

Correlation Between Magnetic Resonance Imaging and Surgical Exploration of the Anterolateral Structures of the Acute Anterior Cruciate Ligament-Injured Knee

BACKGROUND

Combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction is associated with improved clinical outcomes as compared with isolated intra-articular reconstruction, but the indications are not precisely defined. It may be the case that patients with proven anterolateral injury on preoperative imaging are most likely to benefit, but the accuracy of magnetic resonance imaging (MRI) is not known.

PURPOSE/HYPOTHESIS

To evaluate the correlation between MRI and surgical exploration in acute ACL-injured knees. The hypothesis was that a positive correlation would be identified between imaging and surgical findings for ALL/capsule and iliotibial band (ITB) injuries and that MRI would be highly sensitive, specific, and accurate.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Between January and May 2016, patients presenting with acute ACL injuries were considered for study eligibility. Included patients underwent 1.5-T MRI, which was evaluated by 3 investigators who attributed a Ferretti grade of injury to the anterolateral structures. At the time of ACL reconstruction, a lateral exploration was undertaken, and macroscopic injuries were identified. An evaluation of correlation between MRI and surgical exploration findings was performed.

RESULTS

Twenty-six patients participated in the study, and 96% had an ALL/capsule injury. The sensitivity, specificity, and accuracy of MRI and the correlation ( K) with surgical exploration findings were as follows, respectively: any ALL/capsule abnormality-88%, 100%, 88.5%, and 0.47; differentiating partial or complete ALL/capsule tears-78.6%, 41.7%, 61.5%, and 0.23; ITB injuries-62.5%, 40%, 50%, and 0.27. The percentage agreement between MRI and surgical findings was 88% for ALL/capsule injury, 65% for ITB injury, and 53% for Ferretti grading.

CONCLUSION

Surgical exploration demonstrates that injuries occur to the anterolateral structures in almost all acute ACL-injured knees. MRI is highly sensitive, specific, and accurate for detection of abnormalities of the ALL/capsule and shows a high percentage of agreement with surgical findings. MRI has low sensitivity, specificity, and accuracy for the diagnosis of ITB injury. The Ferretti grade could not be reliably established from MRI, and there was only fair agreement between MRI and surgical findings with respect to ITB abnormalities and determination of whether ALL/capsular tears were partial or complete.

Assessment of Anterolateral Complex Injuries by Magnetic Resonance Imaging in Patients With Acute Rupture of the Anterior Cruciate Ligament

PURPOSE

To assess anterolateral complex (ALC) injuries in patients with acute anterior cruciate ligament (ACL) rupture on magnetic resonance imaging (MRI).

METHODS

Patients with acute ACL rupture who underwent ACL surgery between 2015 and 2017 and underwent MRI within 6 weeks of the initial trauma were included. Two radiologists assessed magnetic resonance images retrospectively for the status of the ALC, including the iliotibial band (ITB), Kaplan fibers, and anterolateral ligament (ALL), as follows: grade 0, normal; grade 1, periligamentous edema; grade 2, partial tear; and grade 3, complete tear. The findings were analyzed using the Friedman test and weighted κ values.

RESULTS

Sixty-nine MRI scans were reviewed. Of the 69 patients, 51% had associated injuries to the ITB (grade 1, n = 31; grade 2, n = 4), 33% had associated injuries to the Kaplan fibers (grade 1, n = 21; grade 2, n = 2), and 57% had associated injuries to the ALL (grade 1, n = 12; grade 2, n = 22; grade 3, n = 5). We found a significant difference in the frequency and grading between ITB, Kaplan fiber, and ALL injuries (P ≤ .032). Inter-reader agreement for assessing the ALC on MRI was almost perfect (κ ≥ 0.922).

CONCLUSIONS

On the basis of MRI analysis, ALL injuries were found with varying degrees of severity and intensity with noted injuries to associated surrounding fibers in patients with acute ACL rupture.

LEVEL OF EVIDENCE

Level IV, case series.

An Overview of Anatomy and Imaging of the Anterolateral Structures of the Knee

Despite several previous articles in the literature, never before have so many studies with regard to anterolateral knee structures been performed. The anterolateral knee complex consists briefly of the iliotibial band, with its proximal and distal attachments, the joint capsule, and the anterolateral ligament (ALL). The recently introduced ALL has several different descriptions, making it difficult to build a consensus with regard to its anatomy. An extensive description of these structures, particularly the iliotibial band and the ALL, with regard to anatomy and imaging, will be provided in this article.

How weakness of the tensor fascia lata and gluteus maximus may contribute to ACL injury: A new theory

Anterior cruciate ligament (ACL) injuries are common in sports including a significant failure rate following reconstruction. The iliotibial band (ITB) is an important stabilizer of the lateral portion of the knee and also an important lateral rotator of the tibia. Both the tensor fascia lata (TFL) and gluteus maximus (Gmax) muscles insert into the ITB proximally. This paper describes a theory that implicates weakened TFL and Gmax muscles as possible contributors to anterolateral rotatory instability. If the TFL and Gmax are important contributors to anterolateral rotatory instability, physical therapists can emphasize assessing for their weakness and developing a rehabilitation program to restore their strength.

Anterolateral Knee Extra-articular Stabilizers: A Robotic Sectioning Study of the Anterolateral Ligament and Distal Iliotibial Band Kaplan Fibers

BACKGROUND

The individual kinematic roles of the anterolateral ligament (ALL) and the distal iliotibial band Kaplan fibers in the setting of anterior cruciate ligament (ACL) deficiency require further clarification. This will improve understanding of their potential contribution to residual anterolateral rotational laxity after ACL reconstruction and may influence selection of an anterolateral extra-articular reconstruction technique, which is currently a matter of debate. Hypothesis/Purpose: To compare the role of the ALL and the Kaplan fibers in stabilizing the knee against tibial internal rotation, anterior tibial translation, and the pivot shift in ACL-deficient knees. We hypothesized that the Kaplan fibers would provide greater tibial internal rotation restraint than the ALL in ACL-deficient knees and that both structures would provide restraint against internal rotation during a simulated pivot-shift test.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten paired fresh-frozen cadaveric knees (n = 20) were used to investigate the effect of sectioning the ALL and the Kaplan fibers in ACL-deficient knees with a 6 degrees of freedom robotic testing system. After ACL sectioning, sectioning was randomly performed for the ALL and the Kaplan fibers. An established robotic testing protocol was utilized to assess knee kinematics when the specimens were subjected to a 5-N·m internal rotation torque (0°-90° at 15° increments), a simulated pivot shift with 10-N·m valgus and 5-N·m internal rotation torque (15° and 30°), and an 88-N anterior tibial load (30° and 90°).

RESULTS

Sectioning of the ACL led to significantly increased tibial internal rotation (from 0° to 90°) and anterior tibial translation (30° and 90°) as compared with the intact state. Significantly increased internal rotation occurred with further sectioning of the ALL (15°-90°) and Kaplan fibers (15°, 60°-90°). At higher flexion angles (60°-90°), sectioning the Kaplan fibers led to significantly greater internal rotation when compared with ALL sectioning. On simulated pivot-shift testing, ALL sectioning led to significantly increased internal rotation and anterior translation at 15° and 30°; sectioning of the Kaplan fibers led to significantly increased tibial internal rotation at 15° and 30° and anterior translation at 15°. No significant difference was found when anterior tibial translation was compared between the ACL/ALL- and ACL/Kaplan fiber-deficient states on simulated pivot-shift testing or isolated anterior tibial load.

CONCLUSION

The ALL and Kaplan fibers restrain internal rotation in the ACL-deficient knee. Sectioning the Kaplan fibers led to greater tibial internal rotation at higher flexion angles (60°-90°) as compared with ALL sectioning. Additionally, the ALL and Kaplan fibers contribute to restraint of the pivot shift and anterior tibial translation in the ACL-deficient knee.

CLINICAL RELEVANCE

This study reports that the ALL and distal iliotibial band Kaplan fibers restrain anterior tibial translation, internal rotation, and pivot shift in the ACL-deficient knee. Furthermore, sectioning the Kaplan fibers led to significantly greater tibial internal rotation when compared with ALL sectioning at high flexion angles. These results demonstrate increased rotational knee laxity with combined ACL and anterolateral extra-articular knee injuries and may allow surgeons to optimize the care of patients with this injury pattern.

An anatomic study of trifurcate iliotibial bands for correcting valgus knee deformity

BACKGROUND

The iliotibial band (ITB) trifurcates into the anterior, central and posterior branches at the knee level, and sometimes the branches must be selectively released to correct the valgus knee deformity during total knee arthroplasty. However, the anatomical morphology of the trifurcate ITBs has not been investigated.

METHODS

Fifty-two knees from 26 embalmed cadavers were dissected to observe and record the relationship of the three branches given off from the ITB trifurcation. Fourteen parameters with regard to the length, width, thickness, and trifurcate angle of each branch were measured. These parameters were compared between sex and sides (left or right). Meanwhile, the correlations between parameters and subject age, weight and height were assessed.

RESULTS

The longest, widest and thickest branches of the ITB were the posterior band (59.82±5.14mm), anterior band (39.56±4.17mm) and central band (2.61±0.36mm), respectively. The length and thickness of ITB were significantly larger in males than in females (P<0.05). No significant differences were found between sides (P>0.05). The ITB thickness showed a negative correlation with subject age, while the length and width of the ITB were positively correlated with subject height and weight, respectively.

CONCLUSIONS

This study provided an anatomical reference of trifurcate ITBs to help the release of ITB in valgus knees. The anatomical variations regarding the subject's sex, age, height and weight should be considered in the selective release of ITB.

Anterolateral Tenodesis or Anterolateral Ligament Complex Reconstruction: Effect of Flexion Angle at Graft Fixation When Combined With ACL Reconstruction

BACKGROUND

Despite numerous technical descriptions of anterolateral procedures, knowledge is limited regarding the effect of knee flexion angle during graft fixation.

PURPOSE

To determine the effect of knee flexion angle during graft fixation on tibiofemoral joint kinematics for a modified Lemaire tenodesis or an anterolateral ligament (ALL) complex reconstruction combined with anterior cruciate ligament (ACL) reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve cadaveric knees were mounted in a test rig with kinematics recorded from 0° to 90° flexion. Loads applied to the tibia were 90-N anterior translation, 5-N·m internal tibial rotation, and combined 90-N anterior force and 5-N·m internal rotation. Intact, ACL-deficient, and combined ACL plus anterolateral-deficient states were tested, and then ACL reconstruction was performed and testing was repeated. Thereafter, modified Lemaire tenodeses and ALL procedures with graft fixation at 0°, 30°, and 60° of knee flexion and 20-N graft tension were performed combined with the ACL reconstruction, and repeat testing was performed throughout. Repeated-measures analysis of variance and Bonferroni-adjusted t tests were used for statistical analysis.

RESULTS

In combined ACL and anterolateral deficiency, isolated ACL reconstruction left residual laxity for both anterior translation and internal rotation. Anterior translation was restored for all combinations of ACL and anterolateral procedures. The combined ACL reconstruction and ALL procedure restored intact knee kinematics when the graft was fixed in full extension, but when the graft was fixed in 30° and 60°, the combined procedure left residual laxity in internal rotation ( P = .043). The combined ACL reconstruction and modified Lemaire procedure restored internal rotation regardless of knee flexion angle at graft fixation. When the combined ACL reconstruction and lateral procedure states were compared with the ACL-only reconstructed state, a significant reduction in internal rotation laxity was seen with the modified Lemaire tenodesis but not with the ALL procedure.

CONCLUSION

In a knee with combined ACL and anterolateral ligament injuries, the modified Lemaire tenodesis combined with ACL reconstruction restored normal laxities at all angles of flexion for graft fixation (0°, 30°, or 60°), with 20 N of tension. The combined ACL and ALL procedure restored intact knee kinematics when tensioned in full extension.

CLINICAL RELEVANCE

In combined anterolateral procedure plus intra-articular ACL reconstruction, the knee flexion angle is important when fixing the graft. A modified Lemaire procedure restored intact knee laxities when fixation was performed at 0°, 30°, or 60° of flexion. The ALL procedure restored normal laxities only when fixation occurred in full extension.

The Effects of Anterolateral Tenodesis on Tibiofemoral Contact Pressures and Kinematics

BACKGROUND

Anterolateral tenodeses are increasingly popular in combination with intra-articular anterior cruciate ligament reconstructions. Despite the perception of risk of overconstraint and lateral osteoarthritis, evidence is lacking regarding the effect of graft tensioning on knee kinematics and intra-articular compartmental joint pressures.

PURPOSE

To investigate tibiofemoral joint contact pressures and kinematics related to an anterolateral lesion and the effectiveness of a MacIntosh tenodesis in restoring these when varying (1) graft tension and (2) tibial rotation during graft fixation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric knees were tested in a customized rig with femur fixed and tibia free to move from 0° to 90° of flexion. The quadriceps and iliotibial band were loaded by means of a weighted pulley system. At 30° intervals of knee flexion, tibiofemoral contact pressures were measured with a Tekscan sensor and tibiofemoral kinematics were recorded by use of an optical tracking system. The knee was tested intact and then with an anterolateral soft tissue transection. MacIntosh tenodeses were then tested in a randomized order with 20 N or 80 N of graft tension, each with the tibia held in neutral intact alignment or free to rotate.

RESULTS

Tibial anterior translation and internal rotation were significantly increased and lateral contact pressures significantly reduced compared with the intact knee following anterolateral soft tissue cutting ( P < .05). Contact pressures were restored with fixed neutral tibial rotation combined with 20 N or 80 N of graft tension or by a free-hanging tibia with 20 N of graft tension (all P values > .5). Grafts tensioned with 80 N caused significant overconstraint both when the tibia was fixed and free hanging (all P values < .05). Increases in the lateral tibiofemoral contact pressures were also seen when the tibia was free hanging and 80 N was used for graft tension ( P < .05).

CONCLUSION

Anterolateral soft tissue injury caused reduced lateral tibiofemoral contact pressures and altered tibiofemoral kinematics; these were restored with a MacIntosh procedure performed with 20 N of graft tension. If 80 N of graft tension was used, increased lateral contact pressures and overconstraint in internal rotation were seen. With the tibia free hanging, intact contact biomechanics were restored when 20 N of graft tension was applied, but 80 N of graft tension significantly increased lateral tibiofemoral pressures and overconstrained internal rotation. The kinematic and contact pressure effects were significantly correlated: Changes in tibial rotation caused by increased graft tension correlated with elevated lateral articular contact pressure.

CLINICAL RELEVANCE

Controlling tibial position appears important when tensioning anterolateral tenodeses. However, the identified changes were subtle and may not be clinically significant in a fully loaded knee.

A Comprehensive Reanalysis of the Distal Iliotibial Band: Quantitative Anatomy, Radiographic Markers, and Biomechanical Properties

BACKGROUND

The qualitative anatomy of the distal iliotibial band (ITB) has previously been described. However, a comprehensive characterization of the quantitative anatomic, radiographic, and biomechanical properties of the Kaplan fibers of the deep distal ITB has not yet been established. It is paramount to delineate these characteristics to fully understand the distal ITB's contribution to rotational knee stability. Purpose/Hypothesis: There were 2 distinct purposes for this study: (1) to perform a quantitative anatomic and radiographic evaluation of the distal ITB's attachment sites and their relationships to pertinent osseous and soft tissue landmarks, and (2) to quantify the biomechanical properties of the deep (Kaplan) fibers of the distal ITB. It was hypothesized that the distal ITB has definable parameters concerning its anatomic attachments and consistent relationships to surgically pertinent landmarks with correlating plain radiographic findings. In addition, it was hypothesized that the biomechanical properties of the Kaplan fibers would support their role as important restraints against internal rotation.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired, fresh-frozen human cadaveric knees (mean age, 61.1 years; range, 54-65 years) were dissected for anatomic and radiographic purposes. A coordinate measuring device quantified the attachment areas of the distal ITB to the distal femur, patella, and proximal tibia and their relationships to pertinent bony landmarks. A radiographic analysis was performed by inserting pins into the attachment sites of relevant anatomic structures to assess their location relative to pertinent bony landmarks with fluoroscopic guidance. A further biomechanical assessment of 10 cadaveric knees quantified the load to failure and stiffness of the Kaplan fibers' insertion on the distal femur after a preconditioning protocol.

RESULTS

Two separate deep (Kaplan) fiber bundles were identified with attachments to 2 newly identified femoral bony prominences (ridges). The proximal and distal bundles inserted on the distal femur 53.6 mm (95% CI, 50.7-56.6 mm) and 31.4 mm (95% CI, 27.3-35.5 mm) proximal to the lateral epicondyle, respectively. The centers of the bundle insertions were 22.5 mm (95% CI, 19.1-25.9 mm) apart. The total insertion area of the distal ITB on the proximal tibia was 429.1 mm² (95% CI, 349.2-509.1 mm²). A distinct capsulo-osseous layer of the distal ITB was also identified that was intimately related to the lateral knee capsule. Its origin was in close proximity to the lateral gastrocnemius tubercle, and it inserted on the proximal tibia at the lateral tibial tubercle between the fibular head and the Gerdy tubercle. Radiographic analysis supported the quantitative anatomic findings. The mean maximum load during pull-to-failure testing was 71.3 N (95% CI, 41.2-101.4 N) and 170.2 N (95% CI, 123.6-216.8 N) for the proximal and distal Kaplan bundles, respectively.

CONCLUSION

The most important finding of this study was that 2 distinct deep bundles (Kaplan fibers) of the distal ITB were identified. Each bundle of the deep layer of the ITB was associated with a newly identified distinct bony ridge. Radiographic analysis confirmed the measurements previously recorded and established reproducible landmarks for the newly described structures. Biomechanical testing revealed that the Kaplan fibers had a strong attachment to the distal femur, thereby supporting a role in rotational knee stability.

CLINICAL RELEVANCE

The identification of 2 distinct deep fiber (Kaplan) attachments clarifies the function of the ITB more definitively. The results also support the role of the ITB in rotatory knee stability because of the fibers' vectors and their identified maximum loads. These findings provide the anatomic and biomechanical foundation needed for the development of reconstruction or repair techniques to anatomically address these deficiencies in knee ligament injuries.

The iliotibial tract: imaging, anatomy, injuries, and other pathology

The iliotibial tract, also known as Maissiat's band or the iliotibial band, and its associated muscles function to extend, abduct, and laterally rotate the hip, as well as aid in the stabilization of the knee. A select group of associated injuries and pathologies of the iliotibial tract are seen as sequela of repetitive stress and direct trauma. This article intends to educate the radiologist, orthopedist, and other clinicians about iliotibial tract anatomy and function and the clinical presentation, pathophysiology, and imaging findings of associated pathologies. Specifically, this article will review proximal iliotibial band syndrome, Morel-Lavallée lesions, external snapping hip syndrome, iliotibial band syndrome and bursitis, traumatic tears, iliotibial insertional tendinosis and peritendonitis, avulsion fractures at Gerdy's tubercle, and Segond fractures. The clinical management of these pathologies will also be discussed in brief.

Anterolateral ligament abnormalities are associated with peripheral ligament and osseous injuries in acute ruptures of the anterior cruciate ligament

PURPOSE

Few studies have used MRI to identify the ALL. As it was shown that it is not possible to precisely characterize this ligament in all examination, it is important to identify concomitant lesions that can help in diagnosing ALL abnormalities. It is important to characterise this injury due to its association with anterolateral knee instability. Thus, the present study was performed to determine the frequency of ALL injuries in patients with acute ACL rupture and to analyse its associated knee lesions.

METHODS

Patients with acute ACL injuries were evaluated by MRI. Among this population, the ALL was classified as non-visualised, injured or normal. The possible abnormalities of the meniscus, collateral ligaments, popliteus tendon, posterior cruciate ligament, Iliotibial band (ITB), anterolateral capsule and osseus injuries were evaluated. The association of an ALL injury with these other knee structures as well as sex and age was calculated.

RESULTS

Among the 228 knees evaluated, the ALL could not be entirely identified in 61 (26.7%). Of the remaining 167, 66 (39.5%) presented an ALL abnormality and only four (6.1%) were Segond fractures. ALL abnormalities were associated with lesions of the lateral collateral ligament, medial collateral ligament, popliteus tendon, ITB, anterolateral capsule and osseous contusions of the femoral condyle and tibial plateau. No correlation was found with medial meniscus, lateral meniscus and posterior cruciate ligament injuries. There was no association between ALL injuries and gender, and older patients were more likely to present an ALL injury.

CONCLUSION

ALL injuries are present in approximately 40% of ACL injuries, and a minority of these are Segond fractures. These injuries are associated with peripheral ligament injuries, anterolateral structures lesions and bone contusions, but there is no association with meniscal injuries. Surgeons must be aware of these associations to consider an ALL lesion even if it is not completely clear in imaging evaluation, especially if a high degree of anterolateral instability is present on physical examination.

LEVEL OF EVIDENCE

III.

Biomechanical Comparison of Anterolateral Procedures Combined With Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterolateral soft tissue structures of the knee have a role in controlling anterolateral rotational laxity, and they may be damaged at the time of anterior cruciate ligament (ACL) ruptures.

PURPOSE

To compare the kinematic effects of anterolateral operative procedures in combination with intra-articular ACL reconstruction for combined ACL plus anterolateral-injured knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve cadaveric knees were tested in a 6 degrees of freedom rig using an optical tracking system to record the kinematics through 0° to 90° of knee flexion with no load, anterior drawer, internal rotation, and combined loading. Testing was first performed in ACL-intact, ACL-deficient, and combined ACL plus anterolateral-injured (distal deep insertions of the iliotibial band and the anterolateral ligament [ALL] and capsule cut) states. Thereafter, ACL reconstruction was performed alone and in combination with the following: modified MacIntosh tenodesis, modified Lemaire tenodesis passed both superficial and deep to the lateral collateral ligament, and ALL reconstruction. Anterolateral grafts were fixed at 30° of knee flexion with both 20 and 40 N of tension. Statistical analysis used repeated-measures analyses of variance and paired t tests with Bonferroni adjustments.

RESULTS

ACL reconstruction alone failed to restore native knee kinematics in combined ACL plus anterolateral-injured knees ( P < .05 for all). All combined reconstructions with 20 N of tension, except for ALL reconstruction ( P = .002-.01), restored anterior translation. With 40 N of tension, the superficial Lemaire and MacIntosh procedures overconstrained the anterior laxity in deep flexion. Only the deep Lemaire and MacIntosh procedures-with 20 N of tension-restored rotational kinematics to the intact state ( P > .05 for all), while the ALL underconstrained and the superficial Lemaire overconstrained internal rotation. The same procedures with 40 N of tension led to similar findings.

CONCLUSION

In a combined ACL plus anterolateral-injured knee, ACL reconstruction alone failed to restore intact knee kinematics. The addition of either the deep Lemaire or MacIntosh tenodesis tensioned with 20 N, however, restored native knee kinematics.

CLINICAL RELEVANCE

The current study indicates that unaddressed anterolateral injuries, in the presence of an ACL deficiency, result in abnormal knee kinematics that is not restored if only treated with intra-articular ACL reconstruction. Both the modified MacIntosh and modified deep Lemaire tenodeses (with 20 N of tension) restored native knee kinematics at time zero.

MRI of lower extremity impingement and friction syndromes in children

Although generally more common in adults, lower extremity impingement and friction syndromes are also observed in the pediatric age group. Encompassing femoroacetabular impingement, iliopsoas impingement, subspine impingement, and ischiofemoral impingement around the hip; patellar tendon-lateral femoral condyle friction syndrome; iliotibial band friction syndrome; and medial synovial plica syndrome in the knee as well as talocalcaneal impingement on the hindfoot, these syndromes frequently cause pain and may mimic other, and occasionally more ominous, conditions in children. Magnetic resonance imaging (MRI) plays a key role in the diagnosis of musculoskeletal impingement and friction syndromes. Iliopsoas, subspine, and ischiofemoral impingements have been recently described, while some features of femoroacetabular and talocalcaneal impingements have recently gained increased relevance in the pediatric population. Fellowship-trained pediatric radiologists and radiologists with imaging workloads of exclusively or overwhelmingly pediatric patients (particularly those without a structured musculoskeletal imaging program as part of their imaging training) specifically need to be aware of these rare syndromes that mostly have quite characteristic imaging findings. This review highlights MRI features of lower extremity impingement and friction syndromes in children and provides updated pertinent pathophysiologic and clinical data.

The popliteal fibular ligament in acute knee trauma: patterns of injury on MR imaging

OBJECTIVE

To describe the patterns of injury associated with injury to the popliteofibular ligament injury.

MATERIALS AND METHODS

A retrospective review was performed of 180 MRI scans undertaken for acute knee trauma. Scans were excluded if the time of injury was over 4 weeks from the time of the scan, or if there was a history of septic arthritis, inflammatory arthropathy, previous knee surgery, or significant artefact. An agreed criterion for assessing the structures of the posterolateral ligamentous complex was defined and in each scan, the popliteofibular ligament (PFL) was scored as normal or injured. The menisci, ligaments, and tendons of each knee were also assessed.

RESULTS

The mean age was 25.7 years (range, 9-65 years) and 72.2% (n = 130) patients were male. The PFL was injured in 36 cases (20%). There is a significant association between PFL injury and ACL rupture (p = 0.0001), ITB injury (p = 0.0001), PCL injury (p = 0.0373), in addition to associations with injury to other posterolateral corner structures including the lateral collateral ligament (p = 0.0001), biceps femoris tendon (p = 0.0014), and popliteus tendon (p = 0.0014). Of our series of PFL injuries, nine cases (25%) were associated with further injuries of posterolateral corner structures and in 27 cases (75%) the PFL was the only posterolateral corner structure torn.

CONCLUSIONS

PFL injury is not uncommon in acute knee trauma and is associated with significant internal derangement of the knee, especially anterior cruciate ligament rupture, ITB sprain, and injury to other structures within the posterolateral corner.