Posterolateral Corner Structures Research Articles

Posterolateral Corner Reconstruction: Modification of the LaPrade Technique Using Autologous Hamstring Tendon Grafts: “The Popliteofibular Loop”

Posterolateral corner (PLC) injury is a significant cause of knee instability. In recent years, a better understanding of the anatomy and biomechanics of the PLC structures has led to significant advancements in the surgical treatment of this injury. Anatomical reconstruction techniques, particularly the LaPrade technique, have shown promising results. However, in some settings, the reliance on allografts limits the feasibility of this technique, prompting surgeons to seek reproducible alternatives that use autologous grafts, eliminating the need for tissue banks. The purpose of this Technical Note is to describe a modification of the LaPrade technique for PLC reconstruction using autologous hamstring tendon grafts. The surgical technique is described to ensure reproducibility, with particular emphasis on the proposed modifications: the use of autologous grafts (gracilis and semitendinosus tendons); the configuration in which they are used to increase the thickness of the reconstructed structures; and the exclusive fixation with widely available interference screws.

Reconstruction of the Anterior Cruciate Ligament and the Posterolateral Corner With a Single Combined Femoral Tunnel

Background: Posterolateral knee injuries can occur in 16% of patients with acute ligament injuries, and up to 70% have a combined anterior cruciate ligament (ACL) tear. Studies have shown that, in different populations, the distance between the insertion of the popliteus tendon and the lateral collateral ligament (LCL) may be smaller than the 18.5 mm previously reported in the literature. When we have an associated injury of the ACL and the posterolateral corner (PLC), the confluence of tunnels in the lateral femoral condyle can be a potential problem during reconstruction surgery. Indications: The indication of this technique is the combined injury of the ACL and the PLC. Technique Description: The reconstruction is performed with 2 semitendinosus tendons and 1 gracilis tendon. The technique consists of making a tunnel in the lateral wall of the femur, from the outside-in, at the isometric point between the origin of the LCL and insertion of the popliteus tendon, and emerging in the inner wall of the lateral femoral condyle at the anatomic point of the ACL. The graft is passed from the tibia to the femur with the doubled gracilis tendon and the 2 simple semitendinosus tendons for the ACL graft. The remaining portions of the semitendinosus tendons are left for reconstruction of the PLC structures, with one of them going straight to the posterolateral tibial tunnel (reconstructing the popliteus tendon), and the other passing through the fibular head tunnel (reconstructing the LCL) and continuing from the fibular head to the posterolateral tibial tunnel (reconstructing the popliteofibular ligament). Results: Patients undergoing this technique achieved good functional outcomes and a failure rate similar to that reported in the literature for combined ACL and PLC reconstruction. Discussion/Conclusion: This technique is an excellent option for patients with the combined injury of the ACL and the PLC, avoiding the confluence of tunnels in the lateral femoral condyle. It presents good results and acceptable complication rates, compatible with the severity of this lesion. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Patient demographic and magnetic resonance imaging evaluation of isolated posterolateral corner knee injuries.

Posterolateral stability of the knee is maintained by capsular, ligamentous and tendinous structures, which collectively are known as the posterolateral corner (PLC). Injuries to the PLC of the knee rarely occur without associated anterior (ACL) or posterior cruciate (PCL) ligament tears. The main objectives of our study were to report patient demographics and magnetic resonance imaging (MRI) findings of patients with isolated PLC injuries. This study consists of a retrospective analysis of knee MRI from January 2011 to June 2016, in two hospitals in São Paulo, Brazil, where PLC injuries without associated ACL and PCL injuries were identified in MRI by two radiologists specialized in musculoskeletal injuries. Relative and absolute frequencies were used to describe the injuries of each of the PLC structures in the study cases. A total of 23 cases of PLC injuries without associated cruciate ligament injuries were identified. The mean age of patients was 32.0±8.1 years and 91% patients were male. The main sport associated with isolated PLC injury was Brazilian Jiu-Jitsu (48%), followed by soccer (35%). MRI evaluations of the knees showed lateral collateral ligament (LCL) injuries in 70% of cases, popliteus tendon injuries in 26% of cases and distal biceps tendon injuries in 30% of cases. The popliteofibular ligament (PFL) was damaged in 83% of cases. An associated ALL injury was observed in 43% of cases. Isolated PLC injuries occurred mainly in young men when practicing Brazilian Jiu-Jitsu and soccer. The LCL was the most frequently injured larger structure in association, and the capsuloligamentous structures (PFL) were the most frequently injured structures overall. ALL injuries occurred in approximately half of the cases, most often concomitantly with LCL injuries.

Accuracy of Magnetic Resonance Imaging in the Diagnosis of Multiple Ligament Knee Injuries: A Multicenter Study of 178 Patients

Background: Magnetic resonance imaging (MRI) has shown limited diagnostic accuracy for multiple ligament knee injuries (MLKIs), especially posterolateral corner (PLC) injuries. Hypothesis: The diagnostic accuracy of MRI for MLKIs will only be moderate for some knee structures. Patient-related factors and injury patterns could modify the diagnostic accuracy of MRI. Study Design: Cohort study; Level of evidence, 3. Methods: All patients with MLKIs surgically treated between January 2014 and December 2020 in the centers participating in the study were reviewed. We recorded sex, age, mechanism of injury, time from injury to MRI, and vascular and neurological associated lesions. Lesions to the anterior cruciate ligament (ACL), posterior cruciate ligament, medial collateral ligament, lateral collateral ligament (LCL), popliteus tendon, popliteofibular ligament, iliotibial band, biceps tendon, medial and lateral meniscus, and articular cartilage from MRI reports and surgical records were also collected. The sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, diagnostic odds ratio, positive and negative likelihood ratio, and intraclass correlation coefficient of MRI were calculated for each knee structure. With logistic regression, associations between patient and injury characteristics and MRI accuracy were assessed. Results: A total of 178 patients (127 male; mean age, 33.1 years) were included. High-energy trauma was the most common mechanism of injury (50.6%), followed by sports trauma (38.8%) and low-energy trauma (8.4%). The ACL was the structure with the best diagnostic accuracy, diagnostic odds ratio, and positive predictive value (94.4%, 113.2, and 96.8%, respectively). PLC structures displayed the worst diagnostic accuracy among knee ligaments (popliteus tendon: 76.2%; LCL: 80.3%) and diagnostic odds ratio (popliteus tendon: 9.9; LCL: 17.0; popliteofibular ligament: 17.5). MRI was more reliable in detecting the absence of meniscal and chondral lesions than in identifying them. Logistic regression found that the diagnostic accuracy was affected by the Schenck classification, with higher Schenck grades having worse diagnostic accuracy for peripheral structures (iliotibial band, popliteus tendon, and biceps tendon) and improved diagnostic accuracy for the ACL and posterior cruciate ligament. Conclusion: The diagnostic accuracy of MRI for MLKIs largely varied among knee structures, with many of them at risk of a misdiagnosis, especially PLC, meniscal, and chondral lesions. The severity of MLKIs lowered the diagnostic accuracy of MRI for peripheral structures.

The diagnostic accuracy of MRI for evaluating the posterolateral corner in acute knee dislocation.

To investigate the diagnostic performance of preoperative MRI in evaluating posterolateral corner (PLC) structures after acute knee dislocation (KD) and determine the correlation of MRI with operative findings for grading structure integrity. Acute knee (femorotibial) dislocations between 2005 and 2020 with preoperative MRI and surgical posterolateral corner repair were identified from a single academic institution. From MRI, integrity was evaluated for PLC structures: lateral collateral ligament (LCL), popliteus tendon (PT), biceps femoris tendon (BFT), and ligamento-capsular complex (LCC). Frequency of injury to each structure and number of PLC structures torn in each case were tabulated. Diagnostic performance of MRI was determined using surgery as the reference standard. Correlation between MRI and surgery for each PLC structure was determined using kappa. Thirty-nine KD cases (19 right) in 39 patients (28 male) were included, with mean age of 33 years. Mechanism of injury was as follows: high energy 52%, low energy 38%, ultra-low energy 10%. LCL was most frequently torn, in 95% (37/39) of cases. Most commonly, three of four PLC structures were torn in 54% (21/39) of cases. Diagnostic accuracy of MRI was high for LCL 95%, BFT 87%, PT 82%, and LCC 92%. Correlation between MRI and surgical findings was variable: substantial for BFT, moderate for LCL and PT, and fair for LCC. MRI has high accuracy for detecting tears of posterolateral corner stabilizers in the setting of acute KD. However, for grading structure integrity, the correlation of MRI with surgical findings is variable, ranging from fair to substantial. • In acute knee dislocation, MRI has high diagnostic accuracy for detecting tears of posterolateral corner (PLC) structures. • Preoperative MRI should be considered by orthopedic surgeons when there is clinical concern for posterolateral corner instability following acute knee dislocation. • Although MRI is valuable in the preoperative investigation of knee dislocation, clinical assessment and intraoperative exploration may still be required for definitive diagnosis.

Outcomes of Repair and Reconstruction of the Acute Posterolateral Corner Injuries of the Knee Combined with Cruciate Ligaments Injuries.

This study aimed to report objective and subjective knee stability scores for patients who underwent acute repair of avulsed posterolateral corner (PLC) structures or acute reconstruction of midsubstance tears combined with delayed reconstruction of cruciate ligaments. A total of 48 sport and vehicle accident traumatic patients were enrolled in a three-year follow-up study. The patients were investigated by clinical exams, subjective and objective International Knee Documentation Committee (IKDC) score, Tegner score, Lysholm score, and stress imaging. All scores were compared between the reconstruction and repair groups. Subjective IKDC scores were obtained at 83.3±9.6 and 88.3±4.39 for the reconstruction and repair groups, respectively. Only two patients in the reconstruction group had abnormal objective IKDC scores. Based on the Tegner score, 15 out of 18 patients in the repair group and 20 out of 24 patients in the reconstruction group regained their pre-injury functional level. Mean Lysholm scores for the reconstruction and repair groups were estimated at 83.4±8.2 and 88.2±4.1, respectively. Mean lateral joint opening differences between two knees in the reconstruction and repair groups were -0.2±0.1mm and 0.5±0.1mm, respectively. There were no statistically significant differences between groups outcomes. We had no failure of treatment at the final follow-up. Acute intervention within 3 weeks after PLC injuries combined with delayed cruciate ligaments reconstructions showed favorable outcomes. Both repair and reconstruction are effective when deciding based on the type of injury (i.e., avulsion and midsubstance tear).

Incidence of Intraoperative and Postoperative Complications After Posterolateral Corner Reconstruction or Repair: A Systematic Review of the Current Literature

Background: Posterolateral corner (PLC) injuries of the knee are being increasingly recognized and treated in current orthopaedic practice. While there are numerous systematic reviews evaluating the management and outcomes after PLC injuries, there are limited data investigating complications after PLC reconstruction or repair. Purpose: To systematically review the literature to determine the incidence of postoperative complications after the surgical treatment of PLC injury. Study Design: Systematic review; Level of evidence, 4. Methods: The Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (2008-2019), Embase (2008-2019), and MEDLINE (2008-2019) were queried for literature reporting on PLC reconstruction or repair, with or without concomitant ligamentous or meniscal surgery. Data including type of surgery performed, concomitant procedures, and follow-up time were extracted. Complications recorded included intra- and postoperative complications. Results: After the intra- and postoperative complication data of 60 studies (1747 cases) were combined, surgical management of PLC injuries was associated with an intraoperative complication rate of 0.34% (range, 0%-2.8%) and a postoperative complication rate of 20% (range, 0%-51.2%). The most common postoperative complication was arthrofibrosis (range, 0%-20%). The overall infection rate was 1.3% (range, 0%-10%). Four cases of postoperative common peroneal nerve palsy were reported. Failure of reconstruction or repair was reported in 164 (9.4%) of all cases examined (range, 0%-37.1%). Conclusion: Although the intraoperative rate of complications during PLC reconstructions is low, postoperative complications rates of 20% can be expected, including arthrofibrosis, infection, and neurovascular injury. PLC structures repaired or reconstructed failed in 9.4% of the cases.

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.

Comminuted Fibular Head Fractures With Posterolateral Knee Instability: A Novel Repair Technique Using a Tension-Slide Device.

Comminuted proximal fibula fractures or arcuate fractures (OTA/AO 4F1B fractures) can defunction the posterolateral corner (PLC) and result in posterolateral knee instability. Ongoing posterolateral knee instability can limit function, cause significant pain, and lead to early knee arthrosis. The anatomy of the PLC and proximal fibula limits the options for repair of this injury. The ideal method for osteosynthesis of these injuries has not been established. The goals of treatment include reconstitution of posterolateral stability, restoration of the anatomic relationship of PLC structures, and restoration of bone stock that would permit future reconstruction. This article characterizes the injury pattern, outlines the technique, and provides the clinical and radiographic outcomes of osteosynthesis of comminuted fibular head fractures using a novel application of the tension-slide technique.

Collateral Ligament Knee Injuries in Pediatric and Adolescent Athletes.

The majority of research on medial (MCL) and lateral (LCL) collateral ligament injuries has focused on adults and combined collateral/cruciate injuries. The purpose of this study was to determine characteristics associated with isolated collateral ligament injuries in adolescents, and assess timing for return to sports. Electronic medical records were queried to identify patients aged below 17 years who sustained a magnetic resonance imaging-confirmed isolated MCL or LCL injury over an 8-year period. Retrospective review then documented patient and injury characteristics and clinical course. General linear modeling was used to analyze risk factors for prolonged return to sports, continued pain or reinjury. Fifty-one knees (33 in males, 65%), mean age 13.8 years (range, 5 to 17), were identified, of which 40 (78%) had MCL injuries. Over half (29, 57%) of knees had an open distal femoral physis including all 5 bony avulsion injuries. Eleven (22%) had LCL injuries of which 3 (6%) had concurrent posterolateral corner injuries. Forty-two (82%) knees had injuries that occurred during sports. Eleven knees (28%) with MCL tears had a simultaneous patellar instability episode. Knee injuries that occurred during sports had 37% shorter recovery time (P=0.02). Eight knees (16%) experienced a reinjury and 12 (24%) were followed over an extended period of time for various knee issues. Football injuries were more likely to be grade 3 (P=0.03), and football and soccer accounted for all grade III injuries. The mean return to sports was 2.2 months, with grade III cases returning at 2.4 months, and 95% of cases within 4 months. Isolated collateral ligament injuries are rare in adolescent athletes. MCL injuries, one-quarter of which occurred in conjunction with patellar instability events, were 4 times more common than LCL injuries, one quarter of which have other posterolateral corner structures involved. Grade III injuries represent 20% to 25% of collateral ligament injuries and occurred most commonly in football and soccer. Level IV-retrospective case series.

A Comprehensive Review of the Anatomy of Popliteus and Its Clinico-Surgical Relevance

An extensive anatomical knowledge of the muscle popliteus and its tendon is indispensable to understand the posterolateral structures of the knee which is prone to injury compared to the medial knee structures. This study describes all the relevant anatomical details of the muscle and its clinical significance. Anatomical and clinical terms regarding the popliteus muscle are searched using databases and search engines for the collection of literature review. Abstracts and articles describing the posterolateral corner (PLC) structures apart from the muscle studied were excluded. Seventy-six articles were adopted using the inclusion and exclusion criteria, among which 62 articles had fulfilled the need. Original articles dealing with morphology and morphometric analysis of popliteus muscle are scarce. Hence, the finer details of the anatomy of the muscle in various populations are unavailable, which is considered as a deficiency of the study. This article deals with the morphology of the popliteus and its clinical and surgical implications pertaining to the PLC of the knee.

Remnant Preserving or Augmentation SB PCL Reconstruction: Tips and Tricks

Injury to the Posterior Cruciate Ligament (PCL) is thought to account for 3% to 20% of all knee ligament injuries. Accurate diagnosis of the PCL injury is the first step in determining appropriate management. Approximately 60% of PCL injuries are associated with tearing of the Posterolateral Corner (PLC) structures.When the surgery, arthroscopy PCL reconstruction, is decided then we have to think how and what the best technique will be used to reconstruct. Various techniques of PCL Reconstruction Arthroscopy are known that based on research. According the position of PCL, the procedure of reconstruction is more difficult than ACL one. If combined with PLC rupture, all the structures will be reconstructed in one step.Will be proposed the tips and tricks how to do arthroscopy remnant preserving or augmentation single bundle PCL reconstruction, such as: how to preserve the remnant, how to find the position of tibial attachment and what the landmark, how to deliver the graft into the tunnels so preventing “killer turn” on the posterior part of joint, and how to do the proper rehabilitation.By using the Posterior Medial Portal, working with Remnant Preserved of PCL Reconstruction will be made easier. Joint line of medial tibial plateau as a landmark to find the tibial tunnel. About 1.5 cm below the joint line, the point of tibial tunnel is made or directly finding the edge of the ‘shelf’ where the tunnel is made on there. The remnant will be split and the graft will be laid in between.A strong suture material is used to pull the graft with all in side technique. The tibial part of the graft goes in first through the anterolateral portal following the suture material, go into between the remnant and go into the tibial tunnel from posterior to anterior (inside out). The femoral part of the graft will go into the joint together with the wire that carrying the distal end of the graft go into the femoral tunnel. After that we make the finalization of procedure.Finally, a special rehab program is needed to get the good result of PCL reconstruction as a whole.

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.

The results of treatment of combined injuries of the posterior cruciate ligament and structures of the posterior lateral corner of the knee joint

Insufficient attention to the structures of posterolateral knee corner in case of PCL injury can lead to unsatisfactory results. Objective: to improve the results of treatment patients with posterior cruciate ligament injury by determining the indications for restoration of posterolateral knee corner structures. Methods: there were 68 patients without clear signs of rotation instability by Dial and Varus stress tests. But in all cases we observed asymmetry of these tests compare to contralateral leg. Patients were divided into two groups, homogeneous by gender and age: the main group (36 patients, 52.94 %) — restoration of the PCL and the posterolateral structures, comparison group (32 patients, 47.06 %) — only PCL restoration. The results of treatment were evaluated with VAS and IKDS scales. Results: а subjective assessment of patient’s satisfaction was obtained from 36 (100.00 %) patients in the main group and 30 from the comparison group (93.75 %). It was found out that 25 (37.88 %) patients were very satisfied with the early outcome of treatment (6 weeks), 34 (51.52 %) — satisfied, 5 (7.58 %) — partially satisfied, 2 (3.03 %) — not satisfied. Long-term followup results were assessed in 31 (86.11 %) patients of the main group, 24 (75 %) — of comparison group. 30 (96.78 %) patients of the main group and 21 (91.3 %) of comparison group would agree to repeat surgery again. According to the subjective IKDC scale excellent and good results of treatment were found in 87.5 % of the main group, and only 47.37 % in the comparison group; unsatisfactory — at 4.15 and 15.79 % respectively. Conclusions: in all patients with PCL injury who had minor signs of rotational instability, restoration of the PCL and posterolateral structures allowed to get higher rate of excellent and good results after treatment. In patients with PCL injury and asymmetry of external rotation test, it is necessary to reconstruct the PCL and structures of osterolateral corner.

Posterolateral corner repair and reconstruction: overview of current techniques

This manuscript intends to review and discuss the current concepts of posterolateral corner (PLC) repair and reconstruction techniques. There are many different types of repair and reconstruction of the PLC. However, the repairs shall be limited to specific situations and the concept of anatomic reconstructions must be scrutinized, as the indications of these technically demanding procedures. Therefore, this updating study aims to address these topics providing a conceptual approach of PLC techniques, dividing it into three main types: non-anatomic fibular based PLC reconstructions, tibial based two tailed PLC reconstructions non-anatomically reproducing the main PLC structures, and anatomic PLC reconstructions (tibial based two tailed PLC reconstructions anatomically reproducing the main PLC structures). In addition, the authors’ preferred anatomic PLC reconstructions are described, either using allografts or autografts.

MRI Predictors of Posterolateral Corner Instability: A Decision Tree Analysis of Patients with Acute Anterior Cruciate Ligament Tear.

Purpose To determine the diagnostic performance of MRI for helping to predict posterolateral knee instability in patients with acute anterior cruciate ligament (ACL) tear. Materials and Methods This retrospective cohort study was performed in a consecutive series of 162 patients (mean age, 32.8 years ± 10.0 [standard deviation]; 95 men [mean age, 31.0 years ± 9.6] and 67 women [mean age, 35.4 years ± 10.0]) who underwent ACL reconstruction with (n = 19) or without (n = 143) concomitant posterolateral corner (PLC) reconstruction between June 2014 and February 2017. MR images were evaluated by two radiologists. Diagnostic performance of imaging findings was calculated. Clinical evidence of posterolateral instability requiring PLC reconstruction served as reference standard. The most significant predictors of posterolateral instability were determined with decision tree analysis. Results In patients with and without PLC reconstruction, respectively, the lateral collateral ligament was completely torn in 10 of 19 (52.6%) and seven of 143 (4.9%) patients; the posterior cruciate ligament in two of 19 (10.5%) and five of 143 (3.5%) patients; the popliteus tendon in three of 19 (15.8%) and none of 143 (0%) patients; and the biceps femoris tendon in four of 19 (21.1%) and none of 143 (0%) patients (data for reader 1). The smaller structures of the PLC were not constantly viewable. Complete tear or avulsion of the lateral collateral ligament was more frequent in patients who needed PLC reconstruction (P < .001), and decision tree analysis revealed that this finding was the most statistically significant predictor of posterolateral instability. Instability was correctly predicted in 147 of 162 patients (90.7%) by reader 1 and 151 of 162 patients (93.2%) by reader 2. Conclusion Complete tear or avulsion of the lateral collateral ligament was the most significant predictor at MRI of posterolateral instability. Assessment of the smaller posterolateral corner structures did not improve diagnostic performance. © RSNA, 2018 Online supplemental material is available for this article.

Biomechanical influence of deficient posterolateral corner structures on knee joint kinematics: A computational study.

The posterolateral corner (PLC) structures including the popliteofibular ligament (PFL), popliteus tendon (PT) and lateral collateral ligament (LCL) are important soft tissues for posterior translational, external rotational, and varus angulation knee joint instabilities. The purpose of this study was to determine the effects of deficient PLC structures on the kinematics of the knee joint under gait and squat loading conditions. We developed subject-specific computational models with full 12-degree-of-freedom tibiofemoral and patellofemoral joints for four male subjects and one female subject. The subject-specific knee joint models were validated with computationally predicted muscle activation, electromyography data, and experimental data from previous study. According to our results, deficiency of the PFL did not significantly influence knee joint kinematics compared to an intact model under gait loading conditions. Compared with an intact model under gait and squat loading conditions, deficiency of the PT led to significant increases in external rotation and posterior translation, while LCL deficiency increased varus angulation. Deficiency of all PLC structures led to the greatest increases in external rotation, varus angulation, and posterior translation. These results suggest that the PT is an important structure for external rotation and posterior translation, while the LCL is important for varus angulation under dynamic loading conditions. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-8, 2018.

Kinematics of Different Components of the Posterolateral Corner of the Knee in the Lateral Collateral Ligament-intact State: A Human Cadaveric Study

To determine the static stabilizing effects of different anatomical structures of the posterolateral corner (PLC) of the knee in the lateral collateral ligament (LCL)-intact state. Thirteen fresh-frozen human cadaveric knees were dissected and tested using an industrial robot with an optical tracking system. Kinematics were determined for 134N anterior/posterior loads, 10Nm valgus/varus loads, and 5Nm internal/external rotatory loads in 0°, 20°, 30°, 60°, and 90° of knee flexion. The PLC structures were dissected and consecutively released: (I) intact knee joint, (II) with released posterior cruciate ligament (PCL), (III) popliteomeniscal fibers, (IV) popliteofibular ligament, (V) arcuat and popliteotibial fibers, (VI) popliteus tendon (PLT), and (VII) LCL. Repeated-measures analysis of variance was performed with significance set at P < .05. After releasing the PCL, posterior tibial translation increased by 5.2mm at 20° to 9.4mm at 90° of joint flexion (P < .0001). A mild 1.8° varus instability was measured in 0° of flexion (P= .0017). After releasing the PLC structures, posterior tibial translation further increased by 2.9mm at 20° to 5.9mm at 90° of flexion (P < .05) and external rotation angle increased by 2.6° at 0° to 7.9° at 90° of flexion (P < .05, vs II). Varus stability did not decrease. Mild differences between states V and VI were found in 60° and 90° external rotation tests (2.1° and 3.1°; P < .05). The connecting ligaments/fibers to the PLT act as a primary static stabilizer against external rotatory loads and a secondary stabilizer against posterior tibial loads (when PCL is injured). After releasing these structures, most static stabilizing function of the intact PLT is lost. The PLC has no varus-stabilizing function in the LCL-intact knee. Anatomy and function of these structures for primary and secondary joint stability should be considered for clinical diagnostics and when performing surgery inthePLC.

Kinematics of the posterolateral corner of the knee: A human cadaveric cutting study.

Aims and Objectives:The posterolateral corner of the knee consists of different structures, which contribute to instability when damaged after injury or within surgery. Knowing the kinematic influences may help to improve clinical diagnostics and surgical techniques. The purpose was to determine static stabilizing effects of the posterolateral corner by dissecting stepwise all fibers and ligaments (the arcuat complex, AC) connected with the popliteus tendon (PLT) and the influence on lateral stability in the lateral collateral ligament (LCL) intact-state.Materials ans Methods:Kinematics were examined in 13 fresh-frozen human cadaveric knees using a robotic/UFS testing system with an optical tracking system. The knee kinematics were determined for 134 N anterior/posterior loads, 10 Nm valgus/varus loads and 5 Nm internal/external rotational loads in 0°, 20°, 30°, 60° and 90° of knee flexion. The posterolateral corner structures were consecutively dissected: The I.) intact knee joint, II.) with dissected posterior cruciate ligament, III.) meniscofibular/-tibial fibers, IV.) popliteofibular ligament, V.) popliteotibial fascicle (last structure of static AC), VI.) PLT and VII.) LCL.Results:The external rotation angle increased significantly by 2.6° to 7.9° (P<.05) in 0° to 90° of knee flexion and posterior tibial translation increased by 2.9 mm to 5.9 mm in 20° to 90° of knee flexion (P<.05) after cutting the AC/PLT structures (with intact LCL) in contrast to the PCL deficient knee. Differences between dissected static AC and dissected PLT were only found in 60° and 90° external rotation tests (by 2.1° and 3.1°; P<.05). In the other 28 kinematic tests, no significant differences between PLT and AC were found. Cutting the AC/PLT complex did not further decrease varus, valgus or anterior tibial stability in any flexion angle in comparison to the PCL dissected state.Conclusion:The arcuat complex is an important static stabilizer for external rotatory and posterior tibial loads of the knee, even in the lateral collateral ligament intact-state. After dissecting the major parts of the arcuat complex, the static stabilizing function of the popliteus tendon is lost. The arcuat complex has no varus-stabilizing function in the LCL-intact knee. The anatomy and function of these structures for external-rotational and posterior-translational stabilization should be considered for clinical diagnostics and when performing surgery in the posterolateral corner.

Novel Spiked-Washer Repair Is Biomechanically Superior to Suture and Bone Tunnels for Arcuate Fracture Repair.

Injuries to the posterolateral corner of the knee can lead to chronic degenerative changes, external rotation instability, and varus instability if not repaired adequately. A proximal fibula avulsion fracture, referred to as an arcuate fracture, has been described in the literature, but a definitive repair technique has yet to be described. The objective of this study was to present a novel arcuate fracture repair technique, using a spiked-washer with an intramedullary screw, and to compare its biomechanical integrity to a previously described suture and bone tunnel method. Ten fresh-frozen cadaveric knees underwent a proximal fibula osteotomy to simulate a proximal fibula avulsion fracture. The lateral knee capsule and posterior cruciate ligament were also sectioned to create maximal varus instability. Five fibulas were repaired using a novel spiked-washer technique and the other 5 were repaired using the suture and bone tunnel method. The repaired knees were subjected to a monotonic varus load using a mechanical testing system instrument until failure of the repair or associated posterolateral corner structures. Compared with the suture repair group, the spiked-washer repair group demonstrated a 100% increase in stiffness, 100% increase in yield, 110% increase in failure force, and 108% increase in energy to failure. The spiked-washer technique offers superior quasi-static biomechanical performance compared with suture repair with bone tunnels for arcuate fractures of the proximal fibula. Further clinical investigation of this technique is warranted and the results of this testing may lead to improved outcomes and patient satisfaction for proximal fibula avulsion fractures.