The role of the cruciate and posterolateral ligaments in stability of the knee. A biomechanical study

Application of machine learning-based multi-sequence MRI radiomics in diagnosing anterior cruciate ligament tears

OBJECTIVE

To compare the diagnostic power among various machine learning algorithms utilizing multi-sequence magnetic resonance imaging (MRI) radiomics in detecting anterior cruciate ligament (ACL) tears. Additionally, this research aimed to create and validate the optimal diagnostic model.

METHODS

In this retrospective analysis, 526 patients were included, comprising 178 individuals with ACL tears and 348 with a normal ACL. Radiomics features were derived from multi-sequence MRI scans, encompassing T1-weighted imaging and proton density (PD)-weighted imaging. The process of selecting the most reliable radiomics features involved using interclass correlation coefficient (ICC) testing, t tests, and the least absolute shrinkage and selection operator (LASSO) technique. After the feature selection process, five machine learning classifiers were created. These classifiers comprised logistic regression (LR), support vector machine (SVM), K-nearest neighbors (KNN), light gradient boosting machine (LightGBM), and multilayer perceptron (MLP). A thorough performance evaluation was carried out, utilizing diverse metrics like the area under the receiver operating characteristic curve (ROC), specificity, accuracy, sensitivity positive predictive value, and negative predictive value. The classifier exhibiting the best performance was chosen. Subsequently, three models were developed: the PD model, the T1 model, and the combined model, all based on the optimal classifier. The diagnostic performance of these models was assessed by employing AUC values, calibration curves, and decision curve analysis.

RESULTS

Out of 2032 features, 48 features were selected. The SVM-based multi-sequence radiomics outperformed all others, achieving AUC values of 0.973 and 0.927, sensitivities of 0.933 and 0.857, and specificities of 0.930 and 0.829, in the training and validation cohorts, respectively.

CONCLUSION

The multi-sequence MRI radiomics model, which is based on machine learning, exhibits exceptional performance in diagnosing ACL tears. It provides valuable insights crucial for the diagnosis and treatment of knee joint injuries, serving as an accurate and objective supplementary diagnostic tool for clinical practitioners.

Higher rates of fully preserved posterior cruciate ligament in total knee arthroplasty using a double tibial cut: a prospective randomized controlled trial

PURPOSE

In cruciate retaining total knee arthroplasty, posterior cruciate ligament damage may occur during tibial cutting. A prospective randomized study was conducted to investigate whether a novel tibial cutting technique was more effective than the currently used techniques.

MATERIALS AND METHODS

Patients undergoing cruciate retaining total knee arthroplasty were recruited in a prospective, randomized, controlled trial. In 25 patients (group 1) the tibial cut was performed using a double tibial cut technique; in 25 (group 2) and 25 (group 3) patients, the bone island and en bloc resection techniques were performed, respectively. Posterior cruciate ligament integrity and femoral rollback were assessed at the end of surgery. The Oxford Knee Score, WOMAC score and range of motion were assessed postoperatively.

RESULTS

Posterior cruciate ligament was completely preserved in 92% of patients in group 1 and in 64% in group 2 and 3, respectively (p = 0.03). The Oxford Knee Score and WOMAC scores did not differ between groups (p = 0.4). The mean knee flexion was 126.4°, 121.5° and 123.9° in groups 1, 2 and 3, respectively (p = 0.04). The femoral rollback at 120° flexion was 80.7%, 72.2% and 75.4% in groups 1, 2 and 3, respectively (p = 0.01).

CONCLUSIONS

The double cut technique preserves the posterior cruciate ligament at significantly higher rates than the bone island or en bloc resection techniques. Better posterior cruciate ligament preservation may improve the femoral rollback and knee flexion.

LEVEL OF EVIDENCE

Prospective randomized controlled trial, Level I.

Novel ideas for the comprehensive evaluation of varus knee osteoarthritis: radiological measurements of the morphology of the lateral knee joint

BACKGROUND

The lateral anatomical and morphological characteristics of knees with varus knee osteoarthritis (OA) have not received sufficient attention. This study used several radiological parameters to describe the morphological characteristics of the lateral knee with OA to determine whether there are relationships between varus knee OA and parameters such as lateral plateau widening (LPW), proximal fibula curvature (PFC), and fibula height (FH).

METHODS

The study retrospectively analyzed 1072 subjects who underwent standard radiography for diagnosing or evaluating symptomatic knee joint disease. The 163 Kellgren and Lawrence (K-L) grades 0 and I knees were categorized into the no-knee-OA group, and the 909 K-L grades II-IV knees were classified into the knee-OA group. Medial proximal tibial angle, joint line convergence angle, hip-knee-ankle angle, LPW, PFC, and FH were measured. T tests and chi-square tests were used to compare each index between the two groups. Binary logistic regression was performed to examine the correlation between indexes and knee OA occurrence. Ordinal logistic analysis, principal component analysis, and multivariable linear regression analysis were performed to examine the correlations between the three lateral parameters and K-L grades and the degree of varus deformity.

RESULTS

LPW and PFC were significantly greater and FH was significantly smaller in the knee-OA group than in the no-knee-OA group. LPW, PFC, and FH were correlated with knee OA occurrence. One principal component, named the comprehensive principal component score of varus deformity, was extracted from the three indexes, and the total variance of the principal component interpretation was 76.60%. Ordinal logistics and multivariable linear regression analysis showed that, after adjusting for age and BMI, LPW and PFC were positively correlated with K-L grading and varus deformity. FH was significantly and negatively correlated with K-L grading and varus deformity (all P < 0.05).

CONCLUSIONS

Regular morphological changes take place in the lateral knee with varus OA, including lateral dislocation of the tibial plateau, proximal fibula bending, and upward movement of the fibular head. Changes in LPW, PFC, and FH could enable a more comprehensive assessment of varus knee OA occurrence, severity, and deformity. Level of evidence Retrospective Study Level III.

End-to-end deep learning model for segmentation and severity staging of anterior cruciate ligament injuries from MRI

PURPOSE

The purpose of this study was to develop a semi-supervised segmentation and classification deep learning model for the diagnosis of anterior cruciate ligament (ACL) tears on MRI based on a semi-supervised framework, double-linear layers U-Net (DCLU-Net).

MATERIALS AND METHODS

A total of 297 participants who underwent of total of 303 MRI examination of the knee with fat-saturated proton density (PD) fast spin-echo (FSE) sequence in the sagittal plane were included. There were 214 men and 83 women, with a mean age of 37.46 ± 1.40 (standard deviation) years (range: 29-44 years). Of these, 107 participants had intact ACL (36%), 98 had partially torn ACL (33%), and 92 had fully ruptured ACL (31%). The DCLU-Net was combined with radiomic features for enhancing performances in the diagnosis of ACL tear. The different evaluation metrics for both classification (accuracy, sensitivity, accuracy) and segmentation (mean Dice similarity coefficient and root mean square error) were compared individually for each image class across the three phases of the model, with each value being compared to its respective value from the previous phase. Findings at arthroscopic knee surgery were used as the standard of reference.

RESULTS

With the addition of radiomic features, the final model yielded accuracies of 90% (95% CI: 83-92), 82% (95% CI: 73-86), and 92% (95% CI: 87-94) for classifying ACL as intact, partially torn and fully ruptured, respectively. The DCLU-Net achieved mean Dice similarity coefficient and root mean square error of 0.78 (95% CI: 0.71-0.80) and 0.05 (95% CI: 0.06-0.07), respectively, when segmenting the three ACL conditions with pseudo data (P < 0.001).

CONCLUSION

A dual-modules deep learning model with segmentation and classification capabilities was successfully developed. In addition, the use of semi-supervised techniques significantly reduced the amount of manual segmentation data without compromising performance.

Comparison of three surgical techniques of posterolateral knee reconstruction: A cadaver study

BACKGROUND

Injuries to the posterolateral corner (PLC) of the knee are often overlooked but, require reconstruction in order to restore stability in varus and external rotation. Among the many anatomic and non-anatomic PLC reconstruction techniques available, the modified Larson (mLR), LaPrade (LPR) and Versailles reconstruction (VR) procedures are widely used.

HYPOTHESIS

The hypothesis was that anatomic PLC reconstruction (VR and LPR procedures) provides better restoration and control of external rotation.

PATIENTS AND METHODS

Fifteen fresh-frozen cadaveric knees were tested to compare the 3 procedures. Varus laxity on stress radiographs in full knee extension and external rotatory laxity on dial test at 30° flexion were quantified at 3 phases: intact knee, PLC sectioned and PLC reconstructed.

RESULTS

Mean varus laxity did not differ significantly between techniques in intact knees (p=.14), after PLC sectioning (p=.14) or after PLC reconstruction (p=.17). After PLC reconstruction, varus laxity was restored, with no statistical difference between mLR, VR and LPR compared to intact test values (respectively, -1.0, -1.3 and -1.5; p=.98). In all 3 groups, mean external rotation laxity on dial test at 30° flexion did not significantly differ between intact knees (p=.32) and after PLC sectioning (p=.15). After PLC reconstruction, the mLR technique was significantly less effective in restoring rotational stability than the VR and LPR techniques (p=.025).

DISCUSSION

The VR technique provided similar outcomes to LPR for restoring stability in varus and external rotation. The 2 "anatomic" reconstruction procedures (VR and LPR) were significantly more effective than the modified Larson technique for external rotation control, confirming the study hypothesis. Consequently, it remains preferable to use anatomic techniques in multiligament injuries involving the PLC.

LEVEL OF EVIDENCE

IV, cadaver study.

Relationship between the height of fibular head and the incidence and severity of knee osteoarthritis

The purpose of this study was to investigate the correlation between fibular head height and the incidence and severity of osteoarthritis associated with varus knee deformity. The fibular head height, joint line convergence angle (JLCA) and medial proximal tibial angle (MPTA) were measured in a three-dimensional model. Ordinal multivariate logistic regression was used to analyze the correlation between fibular head height and Kellgren–Lawrence (K–L) grade. Pearson correlation was used to analyze the correlation between fibular head height and K–L grade. A total of 232 patients (232 knees) were finally included in the study. There were significant differences in JLCA and hip–knee–ankle angle (P < 0.05), and both JLCA and hip–knee–ankle angle increased with severe aggravation of K–L grade. Both fibular head height and MPTA decreased as the K–L grade was severely aggravated. There was a significant negative correlation between K–L grade and fibular head height (r = −0.812, P < 0.001). Furthermore, there was a significant negative correlation between fibular head height and hip–knee–ankle angle (r = −0.7905, P < 0.001). In addition to body mass index, fibular head height is a risk factor for the pathogenesis of osteoarthritis associated with varus knee deformity; the smaller the fibular head height, the more severe the degree of varus deformity.

Effect of Sectioning of the Anterior Cruciate Ligament and Posterolateral Structures on Lateral Compartment Gapping: A Randomized Biomechanical Study

Background:

The contribution of anterior cruciate ligament (ACL) injury to lateral instability under varus stress, particularly compared with posterolateral structures, is not well known.

Purpose:

To investigate the effect of sectioning the ACL and posterolateral knee structures on lateral compartment gapping under varus stress.

Study Design:

Controlled laboratory study.

Methods:

Fourteen nonpaired cadaveric knees were randomized to 1 of 2 groups: sequential sectioning of the ACL, fibular collateral ligament (FCL), popliteus tendon (PLT), and popliteofibular ligament (PFL) (ACL-first group) or sequential sectioning of the FCL, PLT, PFL, and ACL (FCL-first group). Knees were loaded onto a custom jig at a 20° flexion angle. A standardized 12-N·m varus moment was applied to each specimen in the intact state and after each randomized sequential-sectioning state. Lateral compartment opening was measured on radiographs to assess the contribution to the increase in the lateral gap caused by resecting the respective structure. The distance was measured by 3 observers on 15 images (5 testing states each imaged 3 times) per specimen, for a total of 210 radiographs. The articular cartilage surfaces were not included in the measurements.

Results:

The mean increase in lateral opening after sectioning all structures (ACL and posterolateral corner) was 4.6 ± 1.8 mm (range, 1.9-7.7 mm). The ACL and FCL sectioning contributed the most to lateral knee opening (1.3 ± 0.6 and 2.2 ± 1.3 mm, respectively). In both groups, lateral gapping >3 mm was achieved only after both the ACL and FCL were sectioned. All comparisons of increased mean gapping distances demonstrated a significant difference with subsequent sequential sectioning of structures, except comparisons between the FCL and PLT and the PLT and PFL. When considering the effect of the ACL on lateral opening, no significant difference was found between sectioning the ACL first or FCL first (P = .387).

Conclusion:

ACL deficiency significantly increased lateral opening under varus stress, regardless of the sequence of injury. The effect of injury to the ACL in addition to the lateral structures should be considered when using varus stress radiographs to evaluate knee injuries.

Clinical Relevance:

With the current findings, understanding the effect of ACL and posterolateral corner injuries on lateral gapping under varus stress can aid in correctly diagnosing knee injuries and determining appropriate treatment plans.

Functional stability: an experimental knee joint cadaveric study on collateral ligaments tension

INTRODUCTION

Applying proper tension to collateral ligaments during total knee arthroplasty surgery is fundamental to achieve optimal implant performance: low tension could lead to joint instability, over-tensioning leads to pain and stiffness. A "functional stability" must be defined and achieved during surgery to guarantee optimal results. In this study, an experimental cadaveric activity was performed to measure the minimum tension required to achieve knee functional stability.

MATERIALS AND METHODS

Ten knee specimens were investigated; femur and tibia were fixed in specifically designed fixtures and clamped to a loading frame; constant displacement rate was applied and resulting tension force was measured. Joint stability was determined as the slope change in the force/displacement curve, representing the activation of both collateral ligaments elastic region; the tension required to reach joint functional stability is then the span between ligaments toe region and this point. Intact, ACL (anterior cruciate ligament)-resected and ACL & PCL (posterior cruciate ligament)-resected knees were tested. The test was performed at different flexion angles; each configuration was analyzed three times.

RESULTS

Results demonstrated an overall tension of 40-50 N to be enough to reach stability in intact knees. Similar values are sufficient in ACL-resected knees, while significantly higher tension is required (up to 60 N) after cruciate ligaments resection. The tension required was slightly higher at 60° of flexion.

CONCLUSION

Results agree with other experimental studies, showing that the tensions required to stabilize a knee joint are lower than the ones applied nowadays via surgical tensioners. To reach functional stability, surgeons should consider such results intraoperatively and avoid ligament laxity or over-tension.

Meniscal Tears, Posterolateral and Posteromedial Corner Injuries, Increased Coronal Plane, and Increased Sagittal Plane Tibial Slope All Influence Anterior Cruciate Ligament-Related Knee Kinematics and Increase Forces on the Native and Reconstructed Anterior Cruciate Ligament: A Systematic Review of Cadaveric Studies

PURPOSE

To obtain a comprehensive list of pathologies that cause increased anterior cruciate ligament (ACL) forces and pathologic knee kinematics to evaluate for in both primary and revision ACL reconstruction to decrease the risk of subsequent graft overload.

METHODS

An electronic search was performed in the Embase and MEDLINE databases for the period between January 1, 1990, and December 10, 2020. All articles investigating medial and lateral meniscal injury, (postero)lateral corner injury, (postero)medial corner/medial collateral ligament injury, valgus alignment, varus alignment, and tibial slope in relation to ACL (graft) force and knee kinematics were included.

RESULTS

Data of 43 studies were included. The studies reported that high-volume medial and lateral meniscectomies, peripheral meniscus tears, medial meniscus ramp tears, lateral meniscus root tears, posterolateral corner injuries, medial collateral ligament tears, increased tibial slope, and valgus and varus alignment were reported to have a significant impact on ACL (graft) force and related knee kinematics.

CONCLUSIONS

This systematic review on biomechanical cadaver studies provides a rationale to systematically identify and treat pathologies in ACL-injured knees, because when undiagnosed or left untreated, these specific concomitant pathologies could lead to ACL graft overload in both primary and revision ACL-reconstructed knees.

CLINICAL RELEVANCE

it is necessary that orthopaedic surgeons who treat ACL-injured knees understand the surgically relevant biomechanical consequences of additional pathologies and use this knowledge to optimize treatment in ACL-injured patients.

Dual Postero-Medial Portal Technique for Posterior Cruciate Ligament Tibial Avulsion Fracture Fixations

The posterior cruciate ligament surgery invariably demands adequate posterior compartment visualisation and instrumentation. The addition of posteromedial (PM) portal during posterior cruciate ligament (PCL) surgeries remains essential. The further addition of one more proximal posteromedial (PM) portal further enhances the instrumentation including suture passage in the substance of PCL or screws insertion and more so obviates the need for trans-septal and posterolateral (PL) portals. This additional PM portal is created in the safe zone under direct visualisation utilising outside-in technique and is spaced to prevent crowding of instrument with arthroscope. The proximal higher PM portal serves as instrument portal and provides optimal trajectory for even arthroscopic screw fixation of PCL avulsion fractures.

Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics

The posterior cruciate ligament (PCL) represents an intra-articular structure composed of two distinct bundles. Considering the anterior and posterior meniscofemoral ligaments, a total of four ligamentous fibre bundles of the posterior knee complex act synergistically to restrain posterior and rotatory tibial loads. Injury mechanisms associated with high-energy trauma and accompanying injury patterns may complicate the diagnostic evaluation and accuracy. Therefore, a thorough and systematic diagnostic workup is necessary to assess the severity of the PCL injury and to initiate an appropriate treatment approach. Since structural damage to the PCL occurs in more than one third of trauma patients experiencing acute knee injury with hemarthrosis, background knowledge for management of PCL injuries is important. In Part 1 of the evidence-based update on management of primary and recurrent PCL injuries, the anatomical, biomechanical, and diagnostic principles are presented. This paper aims to convey the anatomical and biomechanical knowledge needed for accurate diagnosis to facilitate subsequent decision-making in the treatment of PCL injuries.Level of evidence V.

The Pathoanatomy of Posterolateral Corner Ligamentous Disruption in Multiligament Knee Injuries Is Predictive of Peroneal Nerve Injury

BACKGROUND

A description of the precise locations of ligamentous and myotendinous injury patterns of acute posterolateral corner (PLC) injuries and their associated osseous and neurovascular injuries is lacking in the literature.

PURPOSE

To characterize the ligamentous and myotendinous injury patterns and zones of injury that occur in acute PLC injuries and determine associated rates of peroneal nerve palsies and vascular injuries, as well as fracture and dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We retrospectively identified all patients treated for an acute multiligament knee injury (MLKI) at our level 1 trauma center from 2001 to 2018. From this cohort, all patients with PLC injuries were identified. Demographics, involved ligaments and tendons, neurovascular injury, and presence of fracture and dislocation were compared with the larger multiligament knee cohort. Incidence and location of injury of PLC structures-from proximal to midsubstance and distal injury-were recorded.

RESULTS

A total of 100 knees in 100 patients were identified as having MLKIs. A total of 74 patients (74%) had lateral-sided ligament injuries. Of these, 23 (31%) had a peroneal nerve palsy associated with their injury; 10 (14%), a vascular injury; and 23 (31%), a fracture. Patients with PLC injuries had higher rates of peroneal nerve injury as compared with those having acute MLKIs without a PLC injury (31% vs 4%; P = .005). Patients with a complete peroneal nerve palsy (n = 17) were less likely to regain function than those with a partial peroneal nerve palsy (n = 6; 12% vs 100%; P < .0001). Complete injury to the lateral collateral ligament (LCL) occurred in 71 of 74 (96%) PLC injuries, with 3 distinct patterns of injury demonstrated. Fibular avulsion of the LCL was the most common zone of injury (65%), followed by femoral avulsion (20%) and midsubstance tear (15%). Location of injury to the LCL was associated with the rate of peroneal nerve injury, with midsubstance tears and fibular avulsions associated with higher rates of peroneal nerve injury.

CONCLUSION

MLKIs with involvement of the PLC are more likely to suffer peroneal nerve injury. The LCL is nearly always involved, and its location of injury is predictive of peroneal nerve injury. Patients with a complete peroneal nerve palsy at presentation are much less likely to regain function.

Effect of mechanical injury and IL-1β on the expression of LOXs and MMP-1, 2, 3 in PCL fibroblasts after co-culture with synoviocytes

BACKGROUND

Crosstalk between posterior cruciate ligament fibroblasts (PCLfs) and synoviocytes (SCs) significantly modifies the homeostatic balance of the extracellular matrix (ECM) and appears to post a prominent affection for wound healing of PCL. Interleukin-1β (IL-1β) is regarded as a critical factor in acute inflammatory events during ligament injury.

METHODS

In order to confirm the capability of SCs the response of lysyl oxidases (LOXs) and matrix metalloproteinases (MMPs) to IL-1β, the complex cues of the joint cavity following PCL injury were simulated and the effect of IL-1β on the expression of LOXs and MMPs in PCLfs were investigated. PCLfs in both the mono- and co-culture conditions were treated with IL-1β. Cell lysates were collected from the PCLfs and LOXs and MMP-1, 2, 3 expression quantified using quantitative real-time PCR and western bolting.

RESULTS

The results indicated that injury alone elevated the expression of LOXs and MMP-1, 2 and 3. But IL-1β significantly decreased the LOX, LOXL1, and LOXL3 expression, and simultaneously increased MMP-1, 2 and 3 expressions in injured PCLfs. Furthermore, co-culture further suppressed LOXs, but stimulated MMP-1, 2 and 3 expressions when subjected to both mechanical injury and IL-1β treatment. This possibly suggests that a number of soluble factors are secreted that act as mediators that amplify the response of SCs.

CONCLUSION

The results indicated that the SCs could affect the IL-1β-induction of LOXs inhibition and MMPs accumulation, which may be the underlying mechanism of the the poor healing response following PCL injury.

Biomechanics Following Isolated Posterolateral Corner Reconstruction Comparing a Fibular-Based Docking Technique With a Tibia and Fibular-Based Anatomic Technique Show Either Technique is Acceptable

PURPOSE

To analyze the biomechanical integrity of 2 posterolateral corner (PLC) reconstruction techniques using a sophisticated robotic biomechanical system that enables analysis of joint kinematics under dynamic external loads.

METHODS

Eight cadaveric human knee specimens were tested. Five N·m external torque followed by 5 N·m varus torque was dynamically applied to each specimen. The 6 degrees of freedom kinematics of the joint were measured in 4 states (intact, PLC-deficient, fibular-based docking, and anatomic PLC reconstructed) at 30°, 60°, and 90° of flexion. Tibial external rotation (ER) and varus rotation (VR) were compared.

RESULTS

Under external torque, ER significantly increased from the intact state to the PLC-deficient state across all flexion angles. At 30° of flexion, ER was not significantly different between the intact state (19.9°) and fibular-based (18.7°, P = .336) and anatomic reconstructions (14.9°, P = .0977). At 60°, ER was not significantly different between the intact state and fibular-based reconstruction (22.4°, compared with 19.8° in intact; P = .152) but showed overconstraint after anatomic reconstruction (15.7°; P = .0315). At 90°, ER was not significantly different between the intact state and anatomic reconstruction (15.4°, compared with 19.7° in intact; P = .386) but was with the fibular-based technique (23.5°; P = .0125).

CONCLUSION

Both a fibular-based docking technique and an anatomic technique for isolated PLC reconstruction provided appropriate constraint through most tested knee range of motion, yet the fibular-based docking technique underconstrained the knee at 90°, and the anatomic reconstruction overconstrained the knee at 60°. Biomechanically, either technique may be considered for surgical treatment of high-grade isolated PLC injuries.

CLINICAL RELEVANCE

This biomechanical study utilizing clinically-relevant dynamic forces on the knee shows that either a simplified fibular-based docking technique or a more complex anatomic technique may be considered for surgical treatment of high-grade isolated PLC injuries.

Biomechanical evaluation of the influence of posterolateral corner structures on cruciate ligaments forces during simulated gait and squatting

Posterolateral corner (PLC) structures of the knee joint comprise complex anatomical soft tissues that support static and dynamic functional movements of the knee. Most previous studies analyzed posterolateral stability in vitro under static loading conditions. This study aimed to evaluate the contributions of the lateral (fibular) collateral ligament (LCL), popliteofibular ligament (PFL), and popliteus tendon (PT) to cruciate ligament forces under simulated dynamic loading conditions by using selective individual resection. We combined medical imaging and motion capture of healthy subjects (four males and one female) to develop subject-specific knee models that simulated the 12 degrees of freedom of tibiofemoral and patellofemoral joint behaviors. These computational models were validated by comparing electromyographic (EMG) data with muscle activation data and were based on previous experimental studies. A rigid multi-body dynamics simulation using a lower extremity musculoskeletal model was performed to incorporate intact and selective resection of ligaments, based on a novel force-dependent kinematics method, during gait (walking) and squatting. Deficiency of the PLC structures resulted in increased loading on the posterior cruciate ligament and anterior cruciate ligament. Among PLC structures, the PT is the most influential on cruciate ligament forces under dynamic loading conditions.

Knee Ligament Instability Patterns: What Is Clinically Important

The knee dislocation is a severe, complex injury that can be difficult to treat and is fraught with complications. The first step in a successful reconstruction of a multiple ligamentous knee injury is gaining an accurate and thorough understanding of the pattern of instability imparted by the injury. Evaluation begins with a detailed review of radiographic and advanced imaging studies followed by a thorough physical examination, often done under anesthesia, in conjunction with dynamic fluoroscopy. Failure to identify and reconstruct a damaged ligament may place undue stress on adjacent structures, resulting in complications and potential failure of the surgical procedure.

The role of isolated posterior cruciate ligament reconstruction in knees with combined posterior cruciate ligament and posterolateral complex injury

PURPOSE

This is a meta-analysis comparing biomechanical outcomes to determine whether an isolated posterior cruciate ligament (PCL) reconstruction can restore normal knee kinematics in a combined PCL/posterolateral complex (PLC) injury and whether double-bundle (DB) PCL reconstruction is superior in controlling posterior and rotational laxity compared with single-bundle (SB) PCL reconstruction in a PCL/PLC-deficient knee.

METHODS

A number of electronic databases were searched for relevant articles published through August 2016 that compared biomechanical outcomes of PCL reconstruction in patients who underwent reconstruction for combined PCL/PLC deficiencies. Data were searched, extracted, analysed, and assessed for quality according to Cochrane Collaboration guidelines, and biomechanical outcomes were evaluated using various outcome values. The results are presented as relative ratios for binary outcomes and standard mean differences for continuous outcomes with 95% confidence intervals.

RESULTS

Five biomechanical studies were included in this meta-analysis. There were significant differences in laxities such as posterior tibial translation (PTT), external rotation, varus rotation, and PTT coupled with external rotation in the isolated PCL reconstruction group compared with the native PCL group. Furthermore, there were no significant differences in laxities such as PTT, external rotation, or varus rotation between the SB and DB PCL reconstruction groups.

CONCLUSION

Isolated PCL reconstruction, whether SB or DB, could not restore normal knee kinematics in the PCL/PLC-deficient knee. In such cases, residual laxity after isolated PCL reconstruction can be controlled successfully with PLC reconstruction. Therefore, simultaneous PCL and PLC reconstruction is recommended for patients with combined PCL/PLC injury.

Rater agreement reliability of the dial test in the ACL-deficient knee

Background

Posterolateral rotatory instability (PLRI) of the knee can easily be missed, because attention is paid to injury of the cruciate ligaments. If left untreated this clinical instability may persist after reconstruction of the cruciate ligaments and may put the graft at risk of failure. Even though the dial test is widely used to diagnose PLRI, no validity and reliability studies of the manual dial test are yet performed in patients. This study focuses on the reliability of the manual dial test by determining the rater agreement.

Methods

Two independent examiners performed the dial test in knees of 52 patients after knee distorsion with a suspicion on ACL rupture. The dial test was performed in prone position in 30°, 60° and 90° of flexion of the knees. ≥10° side-to-side difference was considered a positive dial test. For quantification of the amount of rotation in degrees, a measuring device was used with a standardized 6 Nm force, using a digital torque adapter on a booth. The intra-rater, inter-rater and rater-device agreement were determined by calculating kappa (κ) for the dial test.

Results

A positive dial test was found in 21.2% and 18.0% of the patients as assessed by a blinded examiner and orthopaedic surgeon respectively. Fair inter-rater agreement was found in 30° of flexion, κ_F = 0.29 (95% CI: 0.01 to 0.56), p = 0.044 and 90° of flexion, κ_F = 0.38 (95% CI: 0.10 to 0.66), p = 0.007. Almost perfect rater-device agreement was found in 30° of flexion, κ_C = 0.84 (95% CI: 0.52 to 1.15), p < 0.001. Moderate rater-device agreement was found in 30° and 90° combined, κ_C = 0.50 (95% CI: 0.13 to 0.86), p = 0.008. No significant intra-rater agreement was found.

Conclusions

Rater agreement reliability of the manual dial test is questionable. It has a fair inter-rater agreement in 30° and 90° of flexion.

Posterolateral corner injuries: Epidemiology, anatomy, biomechanics and diagnosis

Increased internal and external rotational laxity of the knee may result from a wide range of pathologies in or around the knee. However, the principal cause of increased external rotational laxity is damage to the posterolateral corner (PLC). The aim of the review is to discuss the epidemiology, anatomy, biomechanics and diagnosis of PLC injuries.

Fibular Collateral Ligament: Varus Stress Radiographic Analysis Using 3 Different Clinical Techniques

Background:

Fibular collateral ligament (FCL) tears are challenging to diagnose. Left untreated, FCL tears lead to residual ligament instability and increased joint loading on the medial compartment of the knee. Additionally, when a concomitant anterior cruciate ligament (ACL) reconstruction is performed, increased forces on reconstruction grafts occur, which may lead to premature graft failure. Stress radiographs constitute a reliable and validated technique for the objective assessment of a complete grade III FCL tear.

Purpose:

To evaluate side-to-side difference (SSD) values of lateral compartment gapping on varus stress radiographs in patients with a grade III injury to the FCL. Additionally, to evaluate the reliability and reproducibility of 3 different measurement techniques that used various radiographic reference points.

Study Design:

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

Methods:

Inclusion criteria were patients who sustained an FCL with or without a concomitant ACL injury and underwent a combined FCL + ACL reconstruction between 2010 and 2016. Patients were excluded if they had a complete posterolateral corner injury, open physes, intra-articular fracture, meniscal root tear, other ligament injury, or prior surgery on either knee. All FCL tears were diagnosed with a clinical varus stress examination at 0° and 20° of knee flexion and varus stress radiographs at 20° of knee flexion measured in 3 different locations. The SSD for lateral compartment gapping was obtained from the varus stress radiographs and then statistically compared for interrater and intrarater reliability.

Results:

A total of 98 consecutive patients (50 males, 48 females; 13 isolated FCL injuries, 85 combined ACL + FCL injuries) with mean age 33.6 years (range, 18-69 years) were included. Measurement techniques 1, 2, and 3 had mean ± SD lateral compartment SSDs of 2.4 ± 0.20 mm, 2.2 ± 0.20 mm, and 2.0 ± 0.03 mm, respectively (no significant differences). Interrater reliabilities for the 3 measuring techniques were 0.83, 0.86, and 0.91, respectively, while intrarater reliabilities were 0.99, 0.77, and 0.99, respectively.

Conclusion:

This study demonstrated a lower SSD value of 2.2 mm to be consistent with a grade III FCL tear on clinician-applied varus stress radiographs in the clinical setting. Although all SSD measurement locations had excellent reliability, the method using the midpoint of the lateral tibial plateau was found to be the most reproducible.

Current Concepts of Posterolateral Corner Injuries of the Knee

The number of posterolateral corner (PLC) injury patients has risen owing to the increased motor vehicle accidents and sports activities. Careful examination is required because this injury is easy to overlook and may lead to chronic instability. The purpose of this article is to review the anatomy, biomechanics, diagnosis, classification and, treatment of PLC injuries and summarize the recent literatures regarding the treatment outcomes.

Fast-tracked Rehabilitation and Return to Sport of an Elite Rugby Player with a Complicated Posterolateral Corner Injury and Associated Peroneal Paralysis

Acute posterolateral corner injuries of the knee with associated hamstring avulsions and peroneal paralysis are rare in rugby. Regain of motor function following a complete paralysis is documented to be 38%. To our knowledge, only one case describes return to preinjury level of competitive sport taking up to 27 months. A 24-year-old international level rugby player, a medical student, sustained an acute posterolateral knee injury with associated anterior cruciate ligament tear, bicep femoris and semimembranosus avulsions as well as a complete peroneal paralysis. The patient returned to full-time medical rotation work weeks at 5 months. At 10 months, the patient was considered to have returned to preinjury level of activity having managed a 5 km run, participated regularly in non-contact rugby and performed exercises at 140% of his preinjury maximum. This case report describes the successful outcome of a high-frequency high-intensity rehabilitation.

Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability

Little information is available to surgeons regarding how the lateral structures prevent instability in the replaced knee. The aim of this study was to quantify the lateral soft-tissue contributions to stability following cruciate-retaining total knee arthroplasty (CR TKA). Nine cadaveric knees were tested in a robotic system at full extension, 30°, 60°, and 90° flexion angles. In both native and CR implanted states, ±90 N anterior-posterior force, ±8 Nm varus-valgus, and ±5 Nm internal-external torque were applied. The anterolateral structures (ALS, including the iliotibial band), the lateral collateral ligament (LCL), the popliteus tendon complex (Pop T), and the posterior cruciate ligament (PCL) were transected and their relative contributions to stabilizing the applied loads were quantified. The LCL was found to be the primary restraint to varus laxity (an average 56% across all flexion angles), and was significant in internal-external rotational stability (28% and 26%, respectively) and anterior drawer (16%). The ALS restrained 25% of internal rotation, while the PCL was significant in posterior drawer only at 60° and 90° flexion. The Pop T was not found to be significant in any tests. Therefore, the LCL was confirmed as the major lateral structure in CR TKA stability throughout the arc of flexion and deficiency could present a complex rotational laxity that cannot be overcome by the other passive lateral structures or the PCL. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1902-1909, 2017.

Double-bundle posterior cruciate ligament reconstruction: a biomechanical analysis of simulated early motion and partial and full weightbearing on common reconstruction grafts

PURPOSE

The purpose of this study was to determine the biomechanical effects of simulated immediate motion and weightbearing during rehabilitation on different double-bundle posterior cruciate ligament reconstruction (DB-PCLR) graft options.

METHODS

Nine each of commercially prepared (allograft) Achilles tendon allografts, fresh-frozen (autograft) bone-patellar tendon-bone grafts, and fresh-frozen quadriceps tendon grafts were paired with commercially prepared anterior tibialis allografts, fresh-frozen semitendinosus grafts, and fresh-frozen semitendinosus grafts, respectively. Graft pairs were loaded to simulate early range of motion on a stationary bicycle, partial weightbearing (30 %), and full weightbearing.

RESULTS

Acquired laxity (displacement, mm) between graft pairs was not significantly different during simulated early range of motion. However, during simulated partial weightbearing, the median acquired laxity of the patellar tendon/semitendinosus pair (1.06 mm) was significantly less than that of the quadriceps tendon/semitendinosus (1.50 mm, p = 0.01) and Achilles/anterior tibialis (1.44 mm, p = 0.003) graft pairs. During simulated full weightbearing, significantly less acquired laxity was observed for the patellar tendon/semitendinosus graft pair (2.38 mm) compared to the Achilles/anterior tibialis pair (4.85 mm, p = 0.04), but a significant difference was not observed compared to the QT/semitendinosus graft pair (3.91 mm, n.s.). There were no significant differences in the ultimate loads between any of the graft pairs.

CONCLUSIONS

Simulated early range of motion and early partial weightbearing did not result in clinically significant acquired graft laxity in common graft options utilized for DB-PCLR. However, simulated full weightbearing did result in clinically significant acquired graft laxity, and therefore, early rehabilitation protocols should avoid implementing full weightbearing that could contribute to graft failure.

Physical Examination of Knee Ligament Injuries

The knee is one of the most commonly injured joints in the body. A thorough history and physical examination of the knee facilitates accurate diagnosis of ligament injury. Several examination techniques for the knee ligaments that were developed before advanced imaging remain as accurate or more accurate than these newer imaging modalities. Proper use of these examination techniques requires an understanding of the anatomy and pathophysiology of knee ligament injuries. Advanced imaging can be used to augment a history and examination when necessary, but should not replace a thorough history and physical examination.

Anatomical Characteristics and Biomechanical Properties of the Oblique Popliteal Ligament

This anatomical study sought to investigate the morphological characteristics and biomechanical properties of the oblique popliteal ligament (OPL). Embalmed cadaveric knees were used for the study. The OPL and its surrounding structures were dissected; its morphology was carefully observed, analyzed and measured; its biomechanical properties were investigated. The origins and insertions of the OPL were relatively similar, but its overall shape was variable. The OPL had two origins: one originated from the posterior surface of the posteromedial tibia condyle, merged with fibers from the semimembranosus tendon, the other originated from the posteromedial part of the capsule. The two origins converged and coursed superolaterally, then attached to the fabella or to the tendon of the lateral head of the gastrocnemius and blended with the posterolateral joint capsule. The OPL was classified into Band-shaped, Y-shaped, Z-shaped, Trident-shaped, and Complex-shaped configurations. The mean length, width, and thickness of the OPL were 39.54, 22.59, and 1.44 mm, respectively. When an external rotation torque (18 N·m) was applied both before and after the OPL was sectioned, external rotation increased by 8.4° (P = 0.0043) on average. The OPL was found to have a significant role in preventing excessive external rotation and hyperextension of the knee.

The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model

Objectives

The aim of the current study was to analyse the effects of posterior cruciate ligament (PCL) deficiency on forces of the posterolateral corner structure and on tibiofemoral (TF) and patellofemoral (PF) contact force under dynamic-loading conditions.

Methods

A subject-specific knee model was validated using a passive flexion experiment, electromyography data, muscle activation, and previous experimental studies. The simulation was performed on the musculoskeletal models with and without PCL deficiency using a novel force-dependent kinematics method under gait- and squat-loading conditions, followed by probabilistic analysis for material uncertain to be considered.

Results

Comparison of predicted passive flexion, posterior drawer kinematics and muscle activation with experimental measurements showed good agreement. Forces of the posterolateral corner structure, and TF and PF contact forces increased with PCL deficiency under gait- and squat-loading conditions. The rate of increase in PF contact force was the greatest during the squat-loading condition. The TF contact forces increased on both medial and lateral compartments during gait-loading conditions. However, during the squat-loading condition, the medial TF contact force tended to increase, while the lateral TF contact forces decreased. The posterolateral corner structure, which showed the greatest increase in force with deficiency of PCL under both gait- and squat-loading conditions, was the popliteus tendon (PT).

Conclusion

PCL deficiency is a factor affecting the variability of force on the PT in dynamic-loading conditions, and it could lead to degeneration of the PF joint.

Cite this article: K-T. Kang, Y-G. Koh, M. Jung, J-H. Nam, J. Son, Y.H. Lee, S-J. Kim, S-H. Kim. The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model. Bone Joint Res 2017;6:31–42. DOI: 10.1302/2046-3758.61.BJR-2016-0184.R1.

Comparison of Anatomic Posterolateral Knee Reconstruction Using 2 Different Popliteofibular Ligament Techniques

BACKGROUND

Anatomic posterolateral knee reconstruction is a surgical procedure that reconstructs the lateral collateral ligament (LCL), the popliteus tendon, and the popliteofibular ligament (PFL). Until recently, diverse techniques have been reported for this reconstruction; however, the gold standard is still a matter of debate.

HYPOTHESIS

Clinical outcomes and stability with tibiofibular-based PFL reconstruction would be better than those with femorofibular-based PFL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The records of 10 patients who underwent anatomic posterolateral knee reconstruction between January 2011 and December 2012 (LCL, popliteus tendon, tibiofibular-based PFL reconstruction [group A]) with a minimum follow-up of 24 months were retrospectively reviewed. Ten patients who underwent anatomic posterolateral knee reconstruction (LCL, popliteus tendon, femorofibular-based PFL reconstruction [group B]) using a split Achilles tendon allograft were recruited into a matched control group. All patients in both groups had an associate posterior cruciate ligament (PCL) injury, and 8 in each group underwent concomitant PCL reconstruction. Clinical outcomes were evaluated with International Knee Documentation Committee (IKDC) subjective, Lysholm, and Tegner activity scale scores. Knee stability was assessed with the dial test for the evaluation of external rotation as well as varus and posterior instability by stress radiography.

RESULTS

The mean (±SD) follow-up period was 29.5 ± 3.8 months in group A and 60.4 ± 33.8 months in group B. There were no clinically significant between-group differences in IKDC subjective scores (group A: 83.8 ± 5.4, group B: 82.7 ± 6.5; P = .853), Lysholm scores (group A: 83.4 ± 5.1, group B: 84.1 ± 7.3; P = .853), or Tegner activity scale scores (group A: 4.8 ± 1.4, group B: 4.2 ± 0.9; P = .436) at the final follow-up. In addition, there was no difference in side-to-side measurements on varus stress radiography (group A: 0.9 ± 0.7 mm, group B: 1.3 ± 1.2 mm; P = .481) or posterior stress radiography (group A: 5.3 ± 1.9 mm, group B: 5.4 ± 2.2 mm; P = .971) at the final follow-up. Although the external rotation grade of the tibia was not significantly different between groups preoperatively (P = .709), it was smaller in group A at the final follow-up (P = .044).

CONCLUSION

There were no significant differences in clinical outcomes or varus stability between the 2 techniques of PFL reconstruction in patients with posterolateral corner injuries who underwent anatomic posterolateral knee reconstruction. However, the external rotation grade of the tibia was smaller in the group that underwent tibiofibular-based PFL reconstruction.

Surgical management of isolated popliteus tendon injuries in paediatric patients

Isolated popliteus avulsion injuries are a rare occurrence, especially in the skeletally immature population. Two cases of isolated popliteus tendon avulsion injuries in paediatric patients were identified and successfully managed with suture anchor reattachment of the avulsed fragment in the anatomic position. The objective of this case report is to raise awareness of orthopaedic surgeons to the rarely encountered isolated popliteus tendon injury that can occur in paediatric patients. Level of evidence Expert opinion, Level V.

Results of multiple ligament injured knees operated by three different strategies

BACKGROUND

Multiple ligament injured knee is generally described for a scenario when at least 2 of the 4 major ligaments are ruptured. The most effective treatment for these injuries remains controversial. This study presents the clinical outcome of 3 surgical strategies based on personalized treatment.

MATERIALS AND METHODS

Thirty two patients with multiple ligament injured knee were treated by 3 surgical strategies in the acute phase. (1) One-stage: Twelve patients treated by repair and reconstruction of all ruptured ligaments in a single operation. (2) Staged: Eleven patients treated by repair or reconstruction of the extraarticular (EA) ligaments and then intraarticular ligaments in 2(nd) stage. (3) EA ligament repair: Nine patients underwent only EA ligaments repair.

RESULTS

The patients were followed up for an average of 34.7 ± 12.1 months. Significant improvements in knee stabilities (P < 0.01), Lysholm score (P < 0.01) and International Knee Documentation Committee grade (P < 0.01) were noticed in all groups. Of the 32 patients, none had gross mal alignment or gait abnormalities at the latest followup. Comparing the 3 groups, a significant difference in Lysholm score was shown between the one stage group and the EA repair group (P = 0.040); additionally, significant differences were found in 2 subscales of knee injury and osteoarthritis outcome score (P < 0.05).

CONCLUSION

Satisfactory clinical and functional outcomes could be achieved adopting the 3 surgical strategies based on personalized treatment. However, a combination of EA repair and intraarticular repair or reconstruction might be more reasonable options for the young and active patients.

Emerging Updates on the Posterior Cruciate Ligament: A Review of the Current Literature

The posterior cruciate ligament (PCL) is recognized as an essential stabilizer of the knee. However, the complexity of the ligament has generated controversy about its definitive role and the recommended treatment after injury. A proper understanding of the functional role of the PCL is necessary to minimize residual instability, osteoarthritic progression, and failure of additional concomitant ligament graft reconstructions or meniscal repairs after treatment. Recent anatomic and biomechanical studies have elucidated the surgically relevant quantitative anatomy and confirmed the codominant role of the anterolateral and posteromedial bundles of the PCL. Although nonoperative treatment has historically been the initial treatment of choice for isolated PCL injury, possibly biased by the historically poorer objective outcomes postoperatively compared with anterior cruciate ligament reconstructions, surgical intervention has been increasingly used for isolated and combined PCL injuries. Recent studies have more clearly elucidated the biomechanical and clinical effects after PCL tears and resultant treatments. This article presents a thorough review of updates on the clinically relevant anatomy, epidemiology, biomechanical function, diagnosis, and current treatments for the PCL, with an emphasis on the emerging clinical and biomechanical evidence regarding each of the treatment choices for PCL reconstruction surgery. It is recommended that future outcomes studies use PCL stress radiographs to determine objective outcomes and that evidence level 1 and 2 studies be performed to assess outcomes between transtibial and tibial inlay reconstructions and also between single- and double-bundle PCL reconstructions.

Femoral fixation strength following soft-tissue posterolateral corner reconstruction using fibular-based technique: Biomechanical analysis of four techniques in normal and low-density synthetic bone

BACKGROUND

Optimal femoral fixation of soft-tissue grafts has been described for anterior cruciate ligament reconstruction. Posterolateral corner reconstruction differs from ACL reconstruction in two ways: (a) soft-tissue fixation into the femur requires two tails and (b) the line of force is different. Our purpose was to determine the optimal femoral fixation of soft-tissue grafts during posterolateral corner reconstructions. We hypothesized that interference screw fixation is the strongest technique in normal-density lateral femoral condyle, whereas, cortically-based fixation techniques are stronger methods in low-density lateral femoral condyle.

METHODS

We evaluated elongation during cyclic loading, yield load, peak load-to-failure, and stiffness of four soft-tissue graft femoral fixation methods during posterolateral corner reconstruction. Our model included bovine flexor tendons and contoured synthetic bones. Grafts were secured to the lateral epicondyle in normal- or low-density bone models using spiked washer, button, interference screw, or button and interference screw. Five specimens for each were tested in each bone density. Analysis of variance using Tukey-Kramer adjustment for multiple hypothesis testing was used. Six cadaver bones whose density was analyzed using computerized tomography scan quantitation were tested using interference screw fixation.

RESULTS

No method produced significantly stronger yield load or peak load-to-failure in normal-density bone. In low-density bone, cortically-based methods produced significantly higher yield load or peak load-to-failure. Yield load or peak load-to-failure was significantly higher in normal-density bone when using spiked washer or interference screw fixation.

CONCLUSION

No femoral fixation method tested produced superior yield load or peak load-to-failure. Spiked washer and interference screw fixation are inferior fixation methods in low-density bone.

CLINICAL RELEVANCE

For fibular-based posterolateral corner reconstructions, all fixation methods tested are acceptable in high-density bone, while cortical fixation methods should be considered in low-density bone.

Traumatic Knee Dislocations: Evaluation, Management, and Surgical Treatment

Knee dislocations are catastrophic injuries that demand emergent evaluation and often require a multidisciplinary approach. Long-term outcome studies are relatively scarce secondary to the variability in any given study population and the wide variety of injury patterns between knee dislocations. Multiple controversies exist with regard to outcomes using various treatment methods (early vs late intervention, graft selection, repair vs reconstruction of medial and lateral structures, rehabilitation regimens). Careful clinical evaluation is essential when knee dislocation is suspected.

Biomechanical effect of posterolateral corner sectioning after ACL injury and reconstruction

PURPOSE

Posterolateral corner structures functionally interact with the ACL. The aim of this study was to investigate the capability of an isolated ACL reconstruction control laxity parameters in a knee with combined ACL and PLC and the increase in terms of laxity produced by the resection of the PC in an ACL-deficient knee.

METHOD

An in vitro cadaveric study was performed on seven knees. The joints were analysed in the following conditions: intact, after ACL resection, after popliteus complex resection, after ACL reconstruction and after LCL. Testing laxity parameters were recorded with an intra-operative navigation system and defined as: AP displacement at 30° and 90° of flexion (AP30 and AP90) applying a 130 N load and IE at 30° and 90° of knee flexion with a 5 N load.

RESULTS

Sectioning the ACL significantly increased the AP30 at 30° and 90° of knee flexion (p < 0.05). At 90° of knee flexion, the resection of the LCL determined a significant increase in terms of AP laxity (p < 0.05). At 90° has been found a significant difference for the IE laxity (p < 0.05) after PC resection. Sectioning the LCL produced a significant increase in IE laxity at 30° and 90° of knee flexion (p < 0.05).

CONCLUSION

Isolated ACL reconstruction is able to control the AP laxity with a combined complete lesion of the PLC at 30° of knee flexion, but not at higher angle of knee flexion. Considering the IE rotations, the reconstruction was not sufficient not even to control a partial lesion of the PLC. These findings suggest that additional surgical procedures should be considerate even when facing combined PLC lesion.

Physical examination and imaging of the lateral collateral ligament and posterolateral corner of the knee

The initial assessment of injury to the lateral collateral ligament and posterolateral corner is often challenging, particularly in the context of a multiligamentous injury. Although advanced imaging techniques have enhanced the evaluation of knee injuries, the significant, and often unique, contribution of clinical examination should not be overlooked. Clinical examination starts with a thorough history, which is instrumental in elucidating not only the patient's symptomatology but also the mechanism of injury. Differentiating between acute and chronic injury and teasing out the patient's functional limitations are instructive in defining the appropriate treatment plan. The treating physician needs patience, vigilance, and a variety of diagnostic tools to reach a precise diagnosis. Each injury should be approached in a methodical and systematic manner to ensure an accurate initial assessment. This review provides a step-wise approach to the clinical assessment of the lateral collateral ligament and posterolateral corner injured knee. Adjunctive imaging modalities and investigations are also discussed.

Posterolateral knee reconstruction

Injury to the cruciate ligaments of the knee commonly occurs in association with posterolateral instability, which can cause severe functional disability including varus, posterior translation, and external rotational instability. Failure to diagnose and treat an injury of the posterolateral corner in a patient who has a tear of the cruciate ligament can also result in the failure of the reconstructed cruciate ligament. There seems to be a consensus of opinion that injury to the posterolateral corner, whether isolated or combined, is best treated by reconstructing the posterolateral corner along with the coexisting cruciate ligament injury, if combined. Commonly proposed methods of reconstructing the posterolateral corner have focused on the reconstruction of the popliteus, the popliteofibular ligament, and the lateral collateral ligament. The aim of this conference is to describe the posterolateral corner reconstruction technique and to provide an algorithm of treatment.

Management of combined anterior or posterior cruciate ligament and posterolateral corner injuries: a systematic review

BACKGROUND

Combined injuries to the posterolateral corner and cruciate ligaments are uncommon. The heterogeneity of injury patterns in many studies complicates the assessment of outcomes.

OBJECTIVE

To assess the prognosis and functional outcomes after surgery for combined injuries to the posterolateral corner and to the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL).

MATERIAL AND METHODS

We systematically reviewed the literature for articles reporting outcomes 1 year or more after surgery for combined injuries to the posterolateral corner and ACL (n=4) or PCL (n=9). Patients with bicruciate injuries were not studied.

RESULTS

Overall, 65% of patients were IKDC A or B after surgery. The mean Lysholm score improved from 67 to 90. Mean time to surgery was 4.43 months in the group with ACL tears and 18.4 months in the group with PCL tears, and mean follow-up was 34.4 and 40.7 months in these two groups, respectively. In the groups with ACL and PCL tears, the proportions of patients classified as IKDC A or B at last follow-up were 81.6% and 81.0%, respectively, whereas 88% and 99% of patients, respectively, were IKDC grade C or D before surgery. The mean Lysholm score improved from 77 to 92 in the group with ACL tears and from 65 to 89 in the group with PCL tears. Improvements in laxity ranged from 28% to 79% in the group with PCL tears.

DISCUSSION

Most of the articles selected for our review provided level III or IV evidence. Functional outcomes were satisfactory but less good than those reported after surgical reconstruction of isolated cruciate ligament tears. Full reconstruction seems the best strategy in patients with combined ACL/posterolateral corner injuries. Outcomes were also good but more variable in the group with PCL/posterolateral corner injuries. The time to surgery, which reflected the time to diagnosis, was shorter in patients with ACL than with PCL tears in addition to the posterolateral corner injury.

LEVEL OF EVIDENCE

Level III (systematic literature review).

Successful nonoperative treatment of isolated popliteus tendon avulsion fractures in two adolescents

Isolated popliteal tendon avulsion fractures are relatively uncommon in the pediatric population as other posterolateral lateral structures are often involved. This report describes two skeletally immature male patients who presented with knee injuries without ligamentous instability and were subsequently diagnosed with isolated popliteus tendon avulsion fractures. Both of these patients were managed nonoperatively and had subjectively full recoveries. As the treatment for isolated popliteal tendon avulsion fractures is still unclear, the report here may contribute to strategies regarding conservative treatment of these injuries.

Rotational profile alterations after anatomic posterolateral corner reconstructions in multiligament injured knees

PURPOSE

Injuries of the posterolateral corner (PLC) are rare and severe knee injuries, resulting in posterolateral rotatory instability and an increase in external rotation. Surgical reconstruction techniques reproducing the normal anatomy showed promising results. In vivo evaluations of static rotational knee laxity at 30° of knee flexion have not been reported so far. The purpose of this study was to evaluate static rotational knee laxity after anatomic PLC reconstructions.

METHODS

This is a retrospective clinical cohort study. Twenty patients with PLC reconstructions with an average follow-up time of 39 ± 22 months and no history of knee trauma or surgery of the contralateral knee were included in the study. They underwent a routine clinical examination and static rotational laxity measurements at 30° of knee flexion in the prone position. Side-to-side differences were recorded and compared to a group of matched controls.

RESULTS

The postoperative IKDC score was graded A for 8 patients, B for 16, C for 6 and D for one patient. The primary goal of the surgical procedure which consists in reducing excessive external tibiofemoral rotation could be reached in 18 of the 20 patients (90%). Anatomic PLC reconstructions yielded a comparable rotational profile in operated and healthy knees in 7 patients (35%). Thirteen patients (65%) presented a significantly altered rotational profile in comparison with a healthy control group. Unexpected increases in internal rotation were found in 8 patients (40%).

CONCLUSION

Anatomic PLC reconstructions reduced excessive external tibiofemoral rotation in a vast majority of patients. Static rotational laxity measurements allowed for a determination of the patients' individual rotational profile after PLC reconstructions. This profile was normalised in only one-third of the patients. The understanding of this finding needs further investigation as well as the clinical impact of rotational profile alterations on knee function.

LEVEL OF EVIDENCE

Diagnostic studies, Level III.