Anatomy and Biomechanics of the Lateral Side of the Knee

Magnetic resonance imaging evaluation of common peroneal nerve injury in acute and subacute posterolateral corner lesion: a retrospective study

Objective

To evaluate qualitative and quantitative magnetic resonance imaging (MRI) criteria for injury of the common peroneal nerve (CPN) in patients with acute or subacute injuries in the posterolateral corner (PLC) of the knee, as well as to evaluate the reproducibility of MRI evaluation of CPN alterations.

Materials and Methods

This was a retrospective study of 38 consecutive patients submitted to MRI and diagnosed with acute or subacute injury to the PLC of the knee (patient group) and 38 patients with normal MRI results (control group). Two musculoskeletal radiologists (designated radiologist A and radiologist B, respectively) evaluated the images. Nerve injury was classified as neurapraxia, axonotmesis, or neurotmesis. Signal strength was measured at the CPN, the tibial nerve (TN), and a superficial vein (SV). The CPN/TN and CPN/SV signal ratios were calculated. The status of each PLC structure, including the popliteal tendon, arcuate ligament, lateral collateral ligament, and biceps tendon, was classified as normal, partially torn, or completely torn, as was that of the cruciate ligaments. For the semiquantitative analysis of interobserver agreement, the kappa statistic was calculated, whereas a receiver operating characteristic (ROC) curve was used for the quantitative analysis.

Results

In the patient group, radiologist A found CPN abnormalities in 15 cases (39.4%)-neurapraxia in eight and axonotmesis in seven-whereas radiologist B found CPN abnormalities in 14 (36.8%)-neurapraxia in nine and axonotmesis in five. The kappa statistic showed excellent interobserver agreement. In the control group, the CPN/TN signal ratio ranged from 0.63 to 1.1 and the CPN/SV signal ratio ranged from 0.16 to 0.41, compared with 1.30-4.02 and 0.27-1.08, respectively, in the patient group. The ROC curve analysis demonstrated that the CPN/TN signal ratio at a cutoff value of 1.39 had high (93.3%) specificity for the identification of nerve damage, compared with 81.3% for the CPN/SV signal ratio at a cutoff value of 0.41.

Conclusion

CPN alterations are common in patients with PLC injury detected on MRI, and the level of interobserver agreement for such alterations was excellent. Calculating the CPN/TN and CPN/SV signal ratios may increase diagnostic confidence. We recommend systematic analysis of the CPN in cases of PLC injury.

Mechanisms of Hamstring Strain Injury: Interactions between Fatigue, Muscle Activation and Function

Isolated injury to the long head of biceps femoris is the most common type of acute hamstring strain injury (HSI). However, the precise hamstring injury mechanism (i.e., sprint-type) is still not well understood, and research is inconclusive as to which phase in the running cycle HSI risk is the greatest. Since detailed information relating to hamstring muscle function during sprint running cannot be obtained in vivo in humans, the findings of studies investigating HSI mechanisms are based on modeling that requires assumptions to be made based on extrapolations from anatomical and biomechanical investigations. As it is extremely difficult to account for all aspects of muscle-tendon tissues that influence function during high-intensity running actions, much of this complexity is not included in these models. Furthermore, the majority of analyses do not consider the influence of prior activity or muscular fatigue on kinematics, kinetics and muscle activation during sprinting. Yet, it has been shown that fatigue can lead to alterations in neuromuscular coordination patterns that could potentially increase injury risk. The present critical review will evaluate the current evidence on hamstring injury mechanism(s) during high-intensity running and discuss the interactions between fatigue and hamstring muscle activation and function.

The Role of the Posterolateral Tibial Slope in the Rotational Instability of the Knee in Patients Affected by a Complete Isolated Anterior Cruciate Ligament Injury: Its Value in the Decision-Making Process during the Anterolateral Ligament Reconstruction

Purpose  The aim of this retrospective, multicenter study was to investigate the correlation between a high degree of rotatory instability, posterolateral tibial slope (PLTS), and anterolateral ligament (ALL) injury. Methods  The study population consisted of 76 adults with isolated, complete noncontact anterior cruciate ligament (ACL) tear. The sample was divided into two groups according to the preoperative degree of rotator instability (group A: pivot-shift test grades 2 and 3; group B: pivot-shift test grade 1). Preoperative magnetic resonance imaging (MRI) assessment included angle of PLTS, posterior shift of the lateral femoral condyle (16 mm) on the tibial plateau, and the presence/absence of ALL injury. The two groups were compared for differences. Results  There was a statistically significant association between pivot-shift test grades 2 and 3 (group A), PLTS slope angle > 9 degrees, and ALL injury ( p  < 0.05). Group A also demonstrated a greater posterior shift of lateral femoral condyle (>11 mm), which was, however, not statistically significant when evaluated as an isolated variable. Conclusion  Our study indicates that an increased PLTS is associated with an increased incidence of ALL injury and an increased grade of pivot shift in patients with ACL tear. Assessment of posterolateral tibial slope on MRI can therefore play a key adjunct role in the surgical planning of ALL reconstruction, especially in cases when ALL damage is radiologically difficult to detect or doubtful. Level of Evidence  This is a retrospective comparative level III study.

Comparison of three fixation techniques for arcuate fractures

PURPOSE

Proximal fibula avulsion fractures, or "arcuate fractures", are an often discussed but poorly defined injury pattern which represent a destabilizing injury to the posterolateral corner of the knee. Historical and recent literature discussing reconstruction and repair techniques exist, but there has been little biomechanical evaluation of repair techniques. The purpose of this study was to evaluate the strength of three type of fixation techniques for arcuate fractures: bone tunnels, a screw and washer, and a novel suture anchor technique.

METHODS

A laboratory model of the arcuate fracture pattern was developed. This was used to create an arcuate fracture in 24 cadaveric specimens. Knees were randomized into fixation with either suture tunnel (ST), screw and washer (SW), or suture anchor (SA) repair. A previously published model for inducing varus stress was applied and a MTS testing system was used to assess fixation ultimate and yield strength.

RESULTS

Fibular fracture occurred during the fixation of one specimen from the ST group and one from the SA group. Analysis of the remaining 22 specimens revealed a mean ultimate strength of 2422.48 N for the ST group, 2271.78 for SW, and 3041.66 for SA (p = 0.390). Yield strengths were 2065.28 for ST, 1882.43 for SW, and 2871.92 for SA (p = 0.224). Analyses of stiffness and total energy applied were not statistically different (p = 0.111 and 0.601, respectively).

CONCLUSION

Biomechanical analysis of three types of arcuate fragment fixation revealed robust fixation among all methods, supporting surgeon preference for fixation. Fixation may depend on the size of bony fragment and whether or not the injury is a bony or soft tissue injury.

Histological analysis of the anterolateral ligament of the knee

Anterolateral ligament (ALL) was recently described as an important structure to control the pivot-shift phenomenon in the knee. Doubts remain regarding its origin and histological properties. The purpose of this study was to identify the ALL histological structure comparing its characteristics with those of the anterior cruciate ligament (ACL) and joint capsule. ALL was harvested in 25 knees during a total knee arthroplasty (TKA) and histologically evaluated investigating for orientation of fibers, adipose tissue, presence of proprioceptors and synovial like coating. Analysis showed significant differences in several aspects between capsule and ALL; analogies were found comparing the ALL with ACL.

A Biomechanical Comparison of the Arciero and LaPrade Reconstruction for Posterolateral Corner Knee Injuries

Background:

Injury to the posterolateral corner (PLC) of the knee requires reconstruction to restore coronal and rotary stability. Two commonly used procedures are the Arciero reconstruction technique (ART) and the LaPrade reconstruction technique (LRT). To the authors’ knowledge, these techniques have not been biomechanically compared against one another.

Purpose:

To identify if one of these reconstruction techniques better restores stability to a PLC-deficient knee and if concomitant injury to the proximal tibiofibular joint or anterior cruciate ligament affects these results.

Study Design:

Controlled laboratory study.

Methods:

Eight matched-paired cadaveric specimens from the midfemur to toes were used. Each specimen was tested in 4 phases: intact PLC (phase 1), PLC sectioned (phase 2), PLC reconstructed (ART or LRT) (phase 3), and tibiofibular (phase 4A) or anterior cruciate ligament (phase 4B) sectioning with PLC reconstructed. Varus angulation and external rotation at 0º, 20º, 30º, 60º, and 90º of knee flexion were quantified at each phase.

Results:

In phase 3, both reconstructions were effective at restoring laxity back to the intact state. However, in phase 4A, both reconstructions were ineffective at stabilizing the joint owing to tibiofibular instability. In phase 4B, both reconstructions had the potential to restrict varus angulation motion. There were no statistically significant differences found between reconstruction techniques for varus angulation or external rotation at any degree of flexion in phase 3 or 4.

Conclusion:

The LRT and ART are equally effective at restoring stability to knees with PLC injuries. Neither reconstruction technique fully restores stability to knees with combined PLC and proximal tibiofibular joint injuries.

Clinical Relevance:

Given these findings, surgeons may select their reconstruction technique based on their experience and training and the specific needs of their patients.

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 Biomechanics of Multiligament Knee Injuries: From Trauma to Treatment

The multiple ligament injured knee is a complex biomechanical environment. When primary stabilizers fail, secondary stabilizers have an increased role. In addition, loss of primary restraints puts undue stress on the remaining intact structures of the knee. Treatment of these injuries requires accurate diagnosis of all injured structures, and careful consideration of repairs and reconstructions that restore the synergistic stability of all ligaments in the knee.

Surgical Repair of Dynamic Snapping Biceps Femoris Tendon

A snapping biceps tendon is an infrequently seen and commonly misdiagnosed pathology, leaving patients with persistent symptoms that can be debilitating. Patients will present with a visible, audible, and/or painful snap over the lateral aspect of their knee when performing squats, sitting in low seats, or participating in activities with deep knee flexion. A thorough knowledge of the anatomy is essential for surgical treatment of this pathology, which is caused by a detachment of the direct arms of the long and short heads of the biceps femoris off the fibular styloid. This Technical Note provides a diagnostic approach, postoperative management, and details of a surgical technique to treat a snapping biceps tendon with an anatomic repair of the long and short head attachments of the biceps femoris to the posterolateral fibular styloid.

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

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

The arcuate fracture: A descriptive radiographic study

PURPOSE

To assess plain radiographic morphology of arcuate fractures in order to identify patterns and help shape treatment algorithm for proximal fibula fracture.

METHODS

A search of radiographic reports at a level 1 trauma center from 2014 to 2016 using MONTAGE search software for the phrases "arcuate fracture", "fibular head avulsion", or "fibular head fracture" was conducted. Descriptive measurements were obtained including dimensions of the fragment, the displacement of the fragment from its anatomic position, and the orientation of the primary fracture line relative to the axis of the fibular diaphysis in both the sagittal and coronal plane. After review of the measurements and radiographs, fracture patterns were assessed based off previous knowledge previous knowledge of posterior lateral corner (PLC) anatomy.

RESULTS

Radiographic reports of 48 knees (48 patients) met inclusion criteria. The distance of fractures from the proximal aspect of the fibula averaged 9.25 ± 5.53 mm on AP radiographs, and 9.42 ± 4.89 mm on lateral radiographs. The medial-to-lateral width of the proximal fragment averaged 20.09 ± 7.94 mm on AP radiographs, while the anterior-to-posterior width measured on lateral radiographs averaged 17.53 ± 8.48 mm. Orientation of the primary fracture line was calculated at an average of 23.04 ± 14.95° from the perpendicular on the AP view, and 21.55 ± 17.44° from the perpendicular on the lateral. Maximal displacement at the primary fracture line on the AP view was 4.95 ± 8.49 mm). Maximal displacement on the lateral measured 3.98 ± 7.01 mm. Recurring fracture patterns were identified and described. Assessment revealed 11 (22.9%) pattern 1 fractures, six (12.5%) pattern 2 fractures, 31 (64.58%) pattern 3 fractures, possibly correlating with anatomical features and fracture mechanism.

CONCLUSIONS

These measurements and recurring patterns in our study shows the heterogeneity of the size and displacement of these fracture fragments and demonstrates the need for further studies in order to create an anatomic descriptive classification for arcuate fractures, which could be used for clinically for treatment.

Increased Accuracy of Varus Stress Radiographs Versus Magnetic Resonance Imaging in Diagnosing Fibular Collateral Ligament Grade III Tears

PURPOSE

To evaluate the diagnostic accuracy of magnetic resonance imaging and varus stress radiographs for fibular collateral ligament (FCL) tears, and compare these modalities to intraoperative findings.

METHODS

All patients who underwent an isolated FCL or combined anterior cruciate ligament (ACL)/FCL reconstruction by a single surgeon between 2010 and 2017 with preoperative varus stress radiographs and magnetic resonance imaging (MRI) were included in this study. A control group was composed of patients with an MRI and intact ACL and FCL. Sensitivity and specificity of diagnosing FCL injuries on MRI were determined based on review by a fellowship-trained musculoskeletal radiologist, blinded to the pathology associated with each patient (FCL injury vs control), and compared with the gold standard of examination under anesthesia, followed by surgical confirmation of an FCL tear at the time of FCL reconstruction. The sensitivity of diagnosing an FCL injury based on varus stress radiographs was also determined. Furthermore, the ability of both imaging modalities to identify an FCL injury was stratified based on acute versus chronic etiology.

RESULTS

A total of 232 patients were included: 98 patients in the FCL tear group (mean age: 33.6 ± 12.2 years) and 134 patients in the control group (mean age: 44.0 ± 17.2 years). Varus stress radiographs were determined to be more sensitive in diagnosing FCL injuries compared with MRI, with an overall sensitivity of 70% compared with 66%, respectively. Based on MRI, overall specificity was 68%. Based on chronicity of the injuries, MRI was more accurate for detecting acute FCL injuries than chronic injuries (P = .002), and varus stress radiographs were more accurate for detecting chronic FCL injuries than acute injuries (P = .041).

CONCLUSIONS

The results support the use of both varus stress radiographs and MRI in diagnosing FCL injuries, because MRI is more sensitive in diagnosing an acute FCL tear, and varus stress radiographs are more sensitive in diagnosing a chronic FCL tear. Both imaging modalities are recommended to diagnose both acute and chronic FCL injuries.

LEVEL OF EVIDENCE

Level II, case-control study.

Editorial Commentary: The Anterolateral Ligament: The Emperor's New Clothes?

In the following editorial commentary, the lateral soft tissues responsible for resisting the pivot shift phenomenon with the anterior cruciate ligament (ACL) are considered. The recent history of the anterolateral ligament (ALL) has led to rapid adoption of surgical techniques that have often not been investigated with scientific due process. A step-by-step approach starts with biomechanical testing to establish the anatomy and biomechanical characteristics of soft tissue structures and questions the importance of the ALL and proposes a more important role for the iliotibial band (ITB) passing between attachments to the distal lateral femur and tibia. Subsequent laboratory testing of various operative options shows superiority of lateral extra-articular tenodeses (LETs) as compared with ALL reconstruction.

Femoral Component External Rotation Affects Knee Biomechanics: A Computational Model of Posterior-stabilized TKA

BACKGROUND

The correct amount of external rotation of the femoral component during TKA is controversial because the resulting changes in biomechanical knee function associated with varying degrees of femoral component rotation are not well understood. We addressed this question using a computational model, which allowed us to isolate the biomechanical impact of geometric factors including bony shapes, location of ligament insertions, and implant size across three different knees after posterior-stabilized (PS) TKA.

QUESTIONS/PURPOSES

Using a computational model of the tibiofemoral joint, we asked: (1) Does external rotation unload the medial collateral ligament (MCL) and what is the effect on lateral collateral ligament tension? (2) How does external rotation alter tibiofemoral contact loads and kinematics? (3) Does 3° external rotation relative to the posterior condylar axis align the component to the surgical transepicondylar axis (sTEA) and what anatomic factors of the femoral condyle explain variations in maximum MCL tension among knees?

METHODS

We incorporated a PS TKA into a previously developed computational knee model applied to three neutrally aligned, nonarthritic, male cadaveric knees. The computational knee model was previously shown to corroborate coupled motions and ligament loading patterns of the native knee through a range of flexion. Implant geometries were virtually installed using hip-to-ankle CT scans through measured resection and anterior referencing surgical techniques. Collateral ligament properties were standardized across each knee model by defining stiffness and slack lengths based on the healthy population. The femoral component was externally rotated from 0° to 9° relative to the posterior condylar axis in 3° increments. At each increment, the knee was flexed under 500 N compression from 0° to 90° simulating an intraoperative examination. The computational model predicted collateral ligament forces, compartmental contact forces, and tibiofemoral internal/external and varus-valgus rotation through the flexion range.

RESULTS

The computational model predicted that femoral component external rotation relative to the posterior condylar axis unloads the MCL and the medial compartment; however, these effects were inconsistent from knee to knee. When the femoral component was externally rotated by 9° rather than 0° in knees one, two, and three, the maximum force carried by the MCL decreased a respective 55, 88, and 297 N; the medial contact forces decreased at most a respective 90, 190, and 570 N; external tibial rotation in early flexion increased by a respective 4.6°, 1.1°, and 3.3°; and varus angulation of the tibia relative to the femur in late flexion increased by 8.4°, 8.0°, and 7.9°, respectively. With 3° of femoral component external rotation relative to the posterior condylar axis, the femoral component was still externally rotated by up to 2.7° relative to the sTEA in these three neutrally aligned knees. Variations in MCL force from knee to knee with 3° of femoral component external rotation were related to the ratio of the distances from the femoral insertion of the MCL to the posterior and distal cuts of the implant; the closer this ratio was to 1, the more uniform were the MCL tensions from 0° to 90° flexion.

CONCLUSIONS

A larger ratio of distances from the femoral insertion of the MCL to the posterior and distal cuts may cause clinically relevant increases in both MCL tension and compartmental contact forces.

CLINICAL RELEVANCE

To obtain more consistent ligament tensions through flexion, it may be important to locate the posterior and distal aspects of the femoral component with respect to the proximal insertion of the MCL such that a ratio of 1 is achieved.

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.

Anatomical knee postero-lateral corner reconstruction: The "Versailles" technique

Postero-lateral knee instability raises surgical challenges. Of the many available reconstruction techniques, few ensure anatomical reconstruction of the postero-lateral corner (PLC). The "Versailles" technique ensures the anatomical reconstruction of the three main PLC stabilisers (lateral collateral ligament, popliteus tendon, and popliteo-fibular ligament) by using either a hamstring autograft or a tendon allograft.

Biomechanics of the Anterolateral Structures of the Knee

This article describes the complex anatomic structures that pass across the lateral aspect of the knee, particularly the iliotibial tract and the underlying anterolateral ligament and capsule. It provides data on their strength and roles in controlling tibiofemoral joint laxity and stability. These findings are discussed in relation to surgery to repair or reconstruct the anatomic structures, or to create tenodeses with similar effect.

Comparison of reaction forces on the anterior cruciate and anterolateral ligaments during internal rotation and anterior drawer forces at different flexion angles of the knee joint

BACKGROUND

Having a complicated anatomy, the knee joint has been further detailed and a new formation defined, the anterolateral ligament (ALL), in recent studies. While the importance of this ligament, which previously was associated with Segond fractures, was explained via clinical, radiologic and biomechanical studies, and basically, is thought to be a fixator structures for the tibia against internal rotation stress. Although in recent studies efficient surgical treatment was applied to patients who underwent anterior cruciate ligament (ACL) operation, some patients having a positive pivot test highlights the clinical importance of the ALL. The aim of this study is to evaluate reaction forces of different flexion angles on the tibia during internal rotation and anterior drawer tests on both the ALL and ACL, and to examine theimportance of this ligament in knee biomechanics by a finite element analysis method.

METHOD

In this study, normal anatomy knee joint was modelled using Computed Tomography images from lower extremity length in DICOM format. 0°, 15°,30°,45°,60°,75° and 90° angles of flexion were applied, respectively, to these models and reaction force vectors formed on both ligaments were examined separately and as total vector and size by applying internal rotation and anterior drawer forces on each model. Non-linear analysis was conducted using ANSYS (version 17) with the same limit conditions applied to all models.

RESULTS

After all models were examined, in general when comparing reaction forces, those on the ACL were found to be higher. However, when vectoral directions were examined, forces on ALL increased with increased flexion ratio and internal rotation momentum. Beyond 30° flexion, the tensile force on the ALL is increased and compressive overload on the ACL occurs.

CONCLUSION

The ALL plays an important role in stability, especially against internal rotation forces, and an increased knee joint flexion ratio increases the stability contribution ratio. In particular, at 30° and higher angles, ACL reflects an antagonist effect and contributes to knee joint stability for rotational and mediolateral transposition.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Morphology of Anterolateral Ligament of the Knee: A Cadaveric Observation with Clinical Insight

Background. The morphology and function of anterolateral ligament (ALL) of the knee are not clearly understood even today with all the sophisticated techniques available. There have been differing descriptions of the ALL of the knee in literature, and not all of them have been named or described clearly. Aim. The present study was undertaken to provide a clear structure/relationship description on ALL. Materials and Methods. We used 24 formalin-fixed cadaveric limbs. Knee regions of the all the limbs were neatly dissected and the ALL was exposed. Its proximal and distal attachments were traced carefully. Middle portion of ALL was removed and processed for histological analysis. Results. ALL was found in one right knee (4.16%). It extended distally from the lateral femoral condyle to the lateral tibial plateau margin. Its attachment on the tibial plateau was located between head of the fibula and Gerdy's tubercle. A strong connection was identified between the ALL and the periphery of the middle third of the lateral meniscus. Histological analysis of ALL confirmed the presence of true ligamentous structure in it with dense connective tissue and plenty of fibroblasts. Conclusion. The prevalence of ALL in different populations along with its clinical significance has been discussed in detail in this paper.

Tunnel collision during simultaneous anterior cruciate ligament and posterolateral corner reconstruction

PURPOSE

To verify the safest angle to drill femoral tunnels in simultaneous anterior cruciate ligament (ACL) and posterolateral corner (PLC) reconstructions to minimize the risk of tunnel collision and to examine the relationship between lateral femoral condyle (LFC) width and tunnel collision occurrence.

METHODS

Ten fresh-frozen cadaveric knees were used. In each knee, anatomical single-bundle ACL femoral tunnels were arthroscopically drilled at 120 and 140 degrees of flexion, and tunnels for popliteus tendon (PLT) and fibular collateral ligament (FCL) were drilled at 20° axial/20° coronal angulations and 10° axial/30° coronal angulations. Three-dimensional computed tomography exams of the knees were performed. The presence of tunnel collision was evaluated, and the minimal distance between tunnels and the LFC width was measured.

RESULTS

Risk of tunnel collision was significantly increased if FCL and PLT tunnels were drilled at 10° axial/30° coronal angulation (P < 0.05). Tunnel collision was noted in only one knee when FCL and PLT tunnels were drilled at 20° axial/20° coronal angulations. Knees with smaller LFC width had significantly higher risk for tunnel collision (P < 0.05).

CONCLUSION

Drilling PLT and FCL femoral tunnels at 20° axial/20° coronal angulation is a safe positioning for simultaneous ACL and PLC reconstructions. However, in smaller knees, the risk for tunnel collision could be greater. Surgeons should consider the possibility of tunnel collision when performing simultaneous ACL and PLC anatomical reconstruction, especially in knees with a small LFC width where the risk for tunnel collision could be greater.

Biomechanical risk factors associated with iliotibial band syndrome in runners: a systematic review

Background

Iliotibial band syndrome is the second most common running injury. A gradual increase in its occurrence has been noted over the past decade. This may be related to the increasing number of runners worldwide. Since the last systematic review, six additional papers have been published, providing an opportunity for this review to explore the previously identified proximal risk factors in more detail. The aim of this systematic review is thus to provide an up to date quantitative synthesis of the trunk, pelvis and lower limb biomechanical risk factors associated with Iliotibial band syndrome in runners and to provide an algorithm for future research and clinical guidance.

Methods

An electronic search was conducted of literature published up until April 2015. The critical appraisal tool for quantitative studies was used to evaluate methodological quality of eligible studies. Forest plots displayed biomechanical findings, mean differences and confidence intervals. Level of evidence and clinical impact were evaluated for each risk factor. A meta-analysis was conducted where possible.

Result

Thirteen studies were included (prospective (n = 1), cross-sectional (n = 12)). Overall the methodological score of the studies was moderate. Female shod runners who went onto developing Iliotibial band syndrome presented with increased peak hip adduction and increased peak knee internal rotation during stance. Female shod runners with Iliotibial band syndrome presented with increased: peak knee internal rotation and peak trunk ipsilateral during stance.

Conclusion

Findings indicate new quantitative evidence about the biomechanical risk factors associated with Iliotibial band syndrome in runners. Despite these findings, there are a number of limitations to this review including: the limited number of studies, small effect sizes and methodological shortcomings. This review has considered these shortcomings and has summarised the best available evidence to guide clinical decisions and plan future research on Iliotibial band syndrome aetiology and risk.

Characterization of the anatomy of the anterolateral ligament of the knee using magnetic resonance imaging

OBJECTIVE

The anterolateral ligament (ALL) may limit tibial internal rotation and pivot-shift following anterior cruciate ligament reconstruction. Previous studies, using magnetic resonance imaging (MRI) to identify this structure, have been inconsistent. We aimed to further characterize the anatomy of this ligament with reference to previous work.

MATERIALS AND METHODS

Institutional Review Board approval was gained and a retrospective study of 154 consecutive 1.5-T MRI studies was performed by a consultant musculoskeletal radiologist. Cases with a lateral compartment or cruciate injury and patients under 16 years were excluded. A total of 100 MRIs (98 patients; 63 males: 35 females; mean age, 45.3 years, range, 16-85 years) were included in the study.

RESULTS

The ALL was visualized partially in 94 (94.0%) of the cases and fully with distinct femoral and tibial fibers in 57 (57.0%) of the cases. Although the femoral origin was discreet in only 57 (57.0%) of cases, the tibial insertion (7.64 ± 1.26 mm below the joint-line) and meniscal attachment were demonstrated in all cases where the ligament was seen. Where the femoral origin was not seen, a broad expansion of the ligament was noted. We identified four types of meniscal attachment (complete, central, bipolar, and inferior-only). The thickness of the ALL, at the level of the joint-line, was 1.75 ± 0.57 mm.

CONCLUSIONS

The ALL is a consistent structure with meniscal and tibial portions identifiable in the majority of MRI studies of the uninjured knee. There is an attachment to the lateral meniscus with anatomical variation described by our subclassification.

Combined anterolateral ligament and anatomic anterior cruciate ligament reconstruction of the knee

Although anatomic anterior cruciate ligament (ACL) reconstruction is established for the surgical treatment of anterolateral knee instability, there remains a significant cohort of patients who continue to experience post-operative instability. Recent advances in our understanding of the anatomic, biomechanical and radiological characteristics of the native anterolateral ligament (ALL) of the knee have led to a resurgent interest in reconstruction of this structure as part of the management of knee instability. This technical note describes our readily reproducible combined minimally invasive technique to reconstruct both the ACL and ALL anatomically using autologous semitendinosus and gracilis grafts. This method of ALL reconstruction can be easily integrated with all-inside ACL reconstruction, requiring minimal additional operative time, equipment and expertise. Level of evidence V.

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament

PURPOSE

The purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics.

METHODS

Three different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation.

RESULTS

The ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role.

CONCLUSION

From this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics.

Clinically relevant biomechanics of the knee capsule and ligaments

The paper describes the concepts of primary and secondary restraints to knee joint stability and explains systematically how the tibia is stabilised against translational forces and rotational torques in different directions and axes, and how those vary across the arc of flexion-extension. It also shows how the menisci act to stabilise the knee, in addition to load carrying across the joint. It compares the properties of the natural stabilising structures with the strength and stiffness of autogenous tissue grafts and relates those strengths to the strength of graft fixation devices. A good understanding of the biomechanical behaviour of these various structures in the knee will help the surgeon in the assessment and treatment of single and multi-ligament injuries.

Injuries to posterolateral corner of the knee: a comprehensive review from anatomy to surgical treatment

Although injuries to the posterolateral corner of the knee were previously considered to be a rare condition, they have been shown to be present in almost 16% of all knee injuries and are responsible for sustained instability and failure of concomitant reconstructions if not properly recognized. Although also once considered to be the "dark side of the knee", increased knowledge of the posterolateral corner anatomy and biomechanics has led to improved diagnostic ability with better understanding of physical and imaging examinations. The management of posterolateral corner injuries has also evolved and good outcomes have been reported after operative treatment following anatomical reconstruction principles.

Mapping of contributions from collateral ligaments to overall knee joint constraint: an experimental cadaveric study

Understanding the contribution of the soft-tissues to total joint constraint (TJC) is important for predicting joint kinematics, developing surgical procedures, and increasing accuracy of computational models. Previous studies on the collateral ligaments have focused on quantifying strain and tension properties under discrete loads or kinematic paths; however, there has been little work to quantify collateral ligament contribution over a broad range of applied loads and range of motion (ROM) in passive constraint. To accomplish this, passive envelopes were collected from nine cadaveric knees instrumented with implantable pressure transducers (IPT) in the collateral ligaments. The contributions from medial and lateral collateral ligaments (LCL) were quantified by the relative contribution of each structure at various flexion angles (0-120 deg) and compound external loads (±10 N m valgus, ±8 N m external, and ±40 N anterior). Average medial collateral ligament (MCL) contributions were highest under external and valgus torques from 60 deg to 120 deg flexion. The MCL showed significant contributions to TJC under external torques throughout the flexion range. Average LCL contributions were highest from 0 deg to 60 deg flexion under external and varus torques, as well as internal torques from 60 deg to 110 deg flexion. Similarly, these regions were found to have statistically significant LCL contributions. Anterior and posterior loads generally reduced collateral contribution to TJC; however, posterior loads further reduced MCL contribution, while anterior loads further reduced LCL contribution. These results provide insight to the functional role of the collaterals over a broad range of passive constraint. Developing a map of collateral ligament contribution to TJC may be used to identify the effects of injury or surgical intervention on soft-tissue, and how collateral ligament contributions to constraint correlate with activities of daily living.

The biomechanical function of the anterolateral ligament of the knee

BACKGROUND

Recent anatomic investigations of the lateral structures of the knee have identified a new ligament, called the anterolateral ligament (ALL). To date, the anterolateral ligament has not been biomechanically tested to determine its function.

HYPOTHESIS

The ALL of the knee will resist internal rotation at high angles of flexion but will not resist anterior drawer forces.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven cadaveric knees were subjected to 134 N of anterior drawer at flexion angles between 0° and 90° and separately to 5 N·m of internal rotation at the same flexion angles. The in situ forces of the ALL, anterior cruciate ligament (ACL), and lateral collateral ligament (LCL) were determined by the principle of superposition.

RESULTS

The contribution of the ALL during internal rotation increased significantly with increasing flexion, whereas that of the ACL decreased significantly. At knee flexion angles greater than 30°, the contribution of the ALL exceeded that of the ACL. During anterior drawer, the forces in the ALL were significantly less than the forces in the ACL at all flexion angles (P < .001). The forces in the LCL were significantly less than those in either the ACL or the ALL at all flexion angles for both anterior drawer and internal rotation (P < .001).

CONCLUSION

The ALL is an important stabilizer of internal rotation at flexion angles greater than 35°; however, it is minimally loaded during anterior drawer at all flexion angles. The ACL is the primary resister during anterior drawer at all flexion angles and during internal rotation at flexion angles less than 35°.

CLINICAL RELEVANCE

Damage to the ALL of the knee could result in knee instability at high angles of flexion. It is possible that a positive pivot-shift sign may be observed in some patients with an intact ACL but with damage to the ALL. This work may have implications for extra-articular reconstruction in patients with chronic anterolateral instability.

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).

Technical note: a multi-dimensional description of knee laxity using radial basis functions

The net laxity of the knee is a product of individual ligament structures that provide constraint for multiple degrees of freedom (DOF). Clinical laxity assessments are commonly performed along a single axis of motion, and lack analyses of primary and coupled motions in terms of translations and rotations of the knee. Radial basis functions (RBFs) allow multiple DOF to be incorporated into a single method that accounts for all DOF equally. To evaluate this method, tibiofemoral kinematics were experimentally collected from a single cadaveric specimen during a manual laxity assessment. A radial basis function (RBF) analysis was used to approximate new points over a uniform grid space. The normalized root mean square errors of the approximated points were below 4% for all DOF. This method provides a unique approach to describing joint laxity that incorporates multiple DOF in a single model.

Fibular shaft allograft support of posterior joint depression in tibial plateau fractures

Posterior depression of the lateral articular surface of the tibial plateau can be difficult to elevate and support with morselized bone graft and internal fixation. Progressive collapse after open reduction and internal fixation has been described and can lead to failure in treatment. A standard anterolateral approach to the tibia may not allow direct reduction and stabilization of posterolateral joint depression given the anatomic barriers of the fibular collateral ligament and the proximal tibiofibular articulation. Posterolateral approaches to the tibial plateau have been described and may allow direct reduction of the articular depression. These approaches, however, require dissection close to the common peroneal nerve, and some approaches also require a proximal fibular osteotomy. The use of an intraosseous fibular shaft allograft as an adjunct to open reduction and internal fixation in select cases of depressed posterolateral tibial plateau fractures allows both reduction of the joint and stabilization of the articular segment through a single approach familiar to many orthopaedic surgeons.

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament

PURPOSE

The purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics.

METHODS

Three different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation.

RESULTS

The ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role.

CONCLUSION

From this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics.

The effect of cortical button location on its post-operative migration in anatomical double-bundle anterior cruciate ligament reconstruction

PURPOSE

To investigate the effect of EndoButton (Smith & Nephew Endoscopy, Andover, MA, USA) location on post-operative migration in anterior cruciate ligament (ACL) reconstruction.

METHODS

Seventy-seven patients underwent anatomical double-bundle ACL reconstruction using EndoButtons. Comparing patient radiographs immediately post-operatively with those at 1 year, migration was defined when EndoButtons moved more than 1 mm or rotated over 5°. Initial location of EndoButtons was evaluated on radiographs immediately post-operatively. We measured distances from the EndoButton to the posterior and distal edge of the femur (D1, D2) on lateral radiographs and distances from the EndoButton to the lateral and distal edge of the femur (D3, D4) on anteroposterior radiographs. The relationship between supracondylar line and the ratio of migration was also investigated.

RESULTS

D1 in the migrated group were significantly lower than those in the non-migrated group (11.8 ± 12.7 vs. 16.0 ± 10.2 mm). D2, D3 and D4 were not of significant difference in the two groups. The ratio of migration in the area posterior to the supracondylar line was significantly higher than that in the anterior area (54.3 vs. 15.1%).

CONCLUSION

EndoButtons, which was located distally and posteriorly, especially in the area posterior to the lateral supracondylar line, migrated more frequently, although migration of the button had no effect on the clinical parameters evaluated in this study.

CLINICAL RELEVANCE

It is preferable to settle EndoButton anteriorly to the lateral supracondylar line in order to avoid its migration for the graft tension due to our findings about the relationship between initial location of EndoButton and the rate of migration.

LEVEL OF EVIDENCE

Prognostic case series, Level IV.

Unified quantification of variation in passive knee joint constraint

The interrelationship that exists between multiple degrees of freedom to produce a net constraint across the range of passive motion of the knee is not fully understood. Manual joint laxity assessments were performed on 28 cadaveric specimens and used to develop a unified description of the passive laxity envelope that incorporated multiple degrees of freedom into a single analysis using radial basis functions. The unified envelopes were then included in a principal component analysis to identify the primary modes of variation. The first three modes of variation constituted 82% of the variation. The first principal component (36.5% explained variation) correlated with changes to the relationship between varus-valgus and internal-external rotation and had the largest impact on internal-external laxity. The second principal component (27.2% explained variation) correlated with a shift in the internal-external envelope. The third principal component (18.3% explained variation) correlated with a shift in the varus-valgus envelope and a change in varus-valgus laxity. This research presents a novel methodology for quantifying complex changes to passive knee constraint, which may be used as a means for objectively scoring joint laxity and evaluating complex relationships between degrees of freedom in a single analysis.

Femoral tunnel drilling angles for the posterolateral corner in multiligamentary knee reconstructions: computed tomography evaluation in a cadaveric model

PURPOSE

The goal of this study was to determine the best angle at which to drill the femoral tunnels of the popliteus tendon (PT) and fibular collateral ligament (FCL) in combined reconstructive procedures so as to avoid either short tunnels or tunnel collisions with the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) femoral tunnels.

METHODS

Eight cadaveric knees were studied. ACL/PCL femoral tunnels were arthroscopically drilled. PT and FCL tunnels were drilled at 0° and 30° axial and coronal angulations. They were scanned by computed tomography to document relations of the PT and FCL tunnels to the intercondylar notch and ACL/PCL tunnels. A minimum tunnel length of 25 mm was required.

RESULTS

Drilling the PT tunnel at 0° axial angulation was associated with an increased risk of tunnel collision with the ACL (P < .001). Interference with the PCL tunnel can be avoided only if the K-wire guiding the PT tunnel is drilled with 30° coronal angulations (P < .001). The minimum tunnel length of the PT could be obtained only with both axial and coronal angulations of 30° (P = .003). Sufficient tunnel lengths of the FCL were obtained at all angulations evaluated (P = .036). However, only the tunnels drilled at 30° axial and 0° coronal angulations did not collapse with the ACL tunnels (P < .001). No intersections between FCL and PT tunnels were observed.

CONCLUSIONS

When posterolateral reconstructions are performed in combination with concomitant anterior and posterior cruciate procedures, PT tunnels should be drilled at 30° axial and 30° coronal angulations. FCL tunnels should be drilled at 30° axial and 0° coronal angulations. These angulations should minimize such potential complications as short tunnels or collisions with the ACL/PCL tunnels.

CLINICAL RELEVANCE

Specific drilling angles are necessary to avoid short tunnels or collisions between the drilled tunnels when FCL and PT femoral tunnels are performed in multiligament knee reconstructions.

COMPARISON OF COMMERCIAL PATELLOFEMORAL ARTHROPLASTY SYSTEMS ON THE BASIS OF PATELLA KINEMATICS, PERI-PATELLAR SOFT TISSUE TENSION AND PROSTHESIS DESIGN

Patellofemoral arthroplasties are desirable when treating isolated patellofemoral osteoarthritis, due to preservation of the tibiofemoral joint. Since few studies report on new commercial patellofemoral prosthesis biomechanics, a musculoskeletal model enabling analysis of subject-specific knee biomechanics was used to compare four patellofemoral replacement systems (A, B, C, and D) to one another. The prostheses were implanted according to manufacturer guidelines, after which the knee flexed and extended under active muscle loading. An increased patellotrochlear index enabled early patella-trochlear groove engagement. The resurfaced patellae were stable in mediolateral shift and anteroposterior displacement, but only Prosthesis A and D provided a smooth transition between the distal prosthesis border and femoral cartilage. A reduction in the anteroposterior condylar distance displaced the patella posteriorly, resulting in reduced peri-patellar soft tissue tension but an increased patella tendon–quadriceps tendon ratio. The tibial tubercle–trochlear groove distance became pathologic in all replacements. The patella will be stable irrespective of the prosthesis used, but Prosthesis A and D seem to provide a better fit to the trochlear groove anatomy. The increased tibial tubercle–trochlear groove distance emphasizes the importance of extensor alignment in combination with the placement of the prosthesis: an increased Q-angle might lead to excessive lateral wear on the patella button. The extensor mechanism load will increase post-surgery based on the rise in the patella tendon–quadriceps tendon ratio which points to a reduced moment arm. This work provides insight into the dynamic biomechanical function and the design of current commercial patellofemoral replacement systems.

Meniscofibular ligament: morphology and functional significance of a relatively unknown anatomical structure

Purpose. A relatively unknown ligamentous structure of the posterolateral corner of the knee joint, the so-called meniscofibular ligament (MFL), was investigated as regards its macroscopic morphology, its histological features, and its reaction to knee movements. Material and Methods. MFL was exposed on 21 fresh-frozen unpaired knee joints. Its microscopic morphology was examined utilizing for comparison the fibular collateral and the popliteofibular ligament. Results. MFL was encountered in 100% of the specimens as a thin striplike fibrous band extending between the lower border of the lateral meniscus and the head of the fibula. MFL was tense during knee extension and external rotation of the tibia, whereas its histological features were similar to those of fibular collateral and popliteofibular ligament. Discussion. Its precise histological nature is studied as well as its tension alterations during knee movements. The potential functional significance of the MFL with respect to its role in avoidance of lateral meniscus and lateral coronary ligament tears is discussed. Conclusions. MFL presumably provides an additional protection to the lateral meniscus during the last stages of knee extension, as well as to the lateral coronary ligament reducing the possibility of a potential rupture.

PATELLA TRACKING WITH PERIPATELLAR SOFT TISSUE STABILIZERS AS A FUNCTION OF DYNAMIC SUBJECT-SPECIFIC KNEE FLEXION

Musculoskeletal modeling has found wide application in joint biomechanics investigations. This technique has been improved by incorporating subject-specific skeletal elements and passive patellofemoral stabilizers in a dynamic analysis. After trochlear engagement, the volunteers' patellae displaced laterally, whereas tilt was subject specific. Comparison of the tilt and mediolateral position values to in vivo MRI values at 30° knee flexion showed a mean accuracy of 84.4% and 96.9%, respectively. Medial patellofemoral ligament tension decreased with knee flexion, while the patellar tendon–quadriceps tendon ratio ranged from 0.4 to 1.2. The patellofemoral contact load–quadriceps tendon load ratio ranged from 0.7 to 1.3, whereas the mediolateral load component–resultant load ratio ranged from 0 to 0.4. Three validated subject-specific musculoskeletal models facilitated the analysis of patellofemoral biomechanics: Subject-specific patella tracking and passive stabilizer response was analyzed as a function of dynamic knee flexion.

Extra-articular techniques in anterior cruciate ligament reconstruction: a literature review

This annotation considers the place of extra-articular reconstruction in the treatment of anterior cruciate ligament (ACL) deficiency. Extra-articular reconstruction has been employed over the last century to address ACL deficiency. However, the technique has not gained favour, primarily due to residual instability and the subsequent development of degenerative changes in the lateral compartment of the knee. Thus intra-articular reconstruction has become the technique of choice. However, intra-articular reconstruction does not restore normal knee kinematics. Some authors have recommended extra-articular reconstruction in conjunction with an intra-articular technique. The anatomy and biomechanics of the anterolateral structures of the knee remain largely undetermined. Further studies to establish the structure and function of the anterolateral structures may lead to more anatomical extra-articular reconstruction techniques that supplement intra-articular reconstruction. This might reduce residual pivot shift after an intra-articular reconstruction and thus improve the post-operative kinematics of the knee.

A three-dimensional anatomy of the posterolateral compartment of the knee: the use of a new technology in the study of musculoskeletal anatomy

BACKGROUND

Recently, an interest has developed in understanding the anatomy of the posterior and posterolateral knee. The posterolateral compartment of the knee corresponds to a complex arrangement of ligaments and myotendinous structures. Undiagnosed lesions in this compartment are the main reason for failure of the anterior and posterior cruciate ligament reconstructions. Understanding the anatomy of these structures is essential to assist in the diagnosis and treatment of these lesions. The aim of this study was to better understand the relationship between these structures of the knee using three-dimensional technology.

METHODS

Ten knees were included from cadaver lower limbs of adult patients. The skin and subcutaneous tissue were removed leaving only the muscle groups and ligaments. The neurovascular bundles and their ramifications were preserved. Images were acquired from the dissections using a Nikon D40 camera with AF-S Nikkor 18-55 mm (1:3.5 5.6 GII ED) and Micro Nikkor 105 mm (1:2.8) lenses. The pair of images were processed using Callipyan 3D and AnaBuilder software, which transforms the two images into one anaglyphic image.

RESULTS

During the dissection of the knees, twelve pictures were acquired and transformed into anaglyphic images.

CONCLUSION

The use of three-dimensional images in this study demonstrates that this technique is useful to improve the knowledge in anatomy of the knee as well as for knee reconstruction surgery.