Jan-Hendrik Naendrup

The anterolateral complex of the knee: a pictorial essay

AbstractInjuries to the anterolateral complex of the knee can result in increased rotatory knee instability. However, to diagnose and treat patients with persistent instability properly, surgeons need to understand the multifactorial genesis as well as the complex anatomy of the anterolateral aspect of the knee in its entirety. While recent research focused primarily on one structure (anterolateral ligament—ALL), the purpose of this pictorial essay is to provide a detailed layer-by-layer description of the anterolateral complex of the knee, consisting of the iliotibial band with its superficial, middle, deep, and capsulo-osseous layer as well as the anterolateral joint capsule. This may help surgeons to not only understand the anatomy of this particular part of the knee, but may also provide guidance when performing extra-articular procedures in patients with rotatory knee instability. Level of evidence V.

The Segond Fracture Is an Avulsion of the Anterolateral Complex.

Background: The Segond fracture was classically described as an avulsion fracture of the anterolateral capsule of the knee. Recently, some authors have attributed its pathogenesis to the “anterolateral ligament” (ALL). Biomechanical studies that have attempted to reproduce this fracture in vitro have reported conflicting findings. Purpose: To determine the anatomic characteristics of the Segond fracture on plain radiographs and magnetic resonance imaging (MRI), to compare this location with the location of the ALL described in prior radiographic and anatomic publications, and to determine the fracture’s attachments to the soft tissue anterolateral structures of the knee. Study Design: Case series; Level of evidence, 4. Methods: A total of 36 anterior cruciate ligament–injured patients with Segond fractures (33 male, 3 female; mean age, 23.2 ± 8.4 years) were enrolled. MRI scans were reviewed to determine the anatomic characteristics of the Segond fracture, including the following: proximal-distal (PD) length, anterior-posterior (AP) width, medial-lateral (ML) width, PD distance to the lateral tibial plateau, AP distance to the Gerdy tubercle (GT), and AP distance from the GT to the posterior aspect of the fibular head. The attachment of the anterolateral structures to the Segond fragment was then categorized as the iliotibial band (ITB) or anterolateral capsule. Interrater reliability of the measurements was determined by calculating the Spearman rank correlation coefficient. MEDLINE, Web of Science, and the Cochrane Library were searched from inception to May 2016 for the following keywords: (1) “Segond fracture,” (2) “anterolateral ligament,” (3) “knee avulsion,” (4) “lateral tibia avulsion,” and (5) “tibial plateau avulsion.” All studies describing the anatomic location of the Segond fracture and the ALL were included in the systematic review. Results: On plain radiographs, the mean distance of the midpoint of the fracture to the lateral tibial plateau was 4.6 ± 2.2 mm. The avulsed fracture had a mean PD length of 9.2 ± 2.5 mm and a mean ML width of 2.4 ± 1.4 mm. On MRI, the mean distance of the proximal fracture to the tibial plateau was 3.4 ± 1.6 mm. The mean PD length was 8.7 ± 2.2 mm, while the mean AP width was 11.1 ± 2.2 mm. The mean distance between the GT and the center of the fracture was 26.9 ± 3.3 mm, while the mean distance between the GT and the posterior fibular head was 53.9 ± 4.4 mm. The mean distance of the midpoint of the fracture to the tibial plateau was 7.8 ± 2.7 mm, while the center of the fracture was 49.9% of the distance between the GT and the posterior aspect of the fibular head. Analysis of soft tissue structures attached to the fragment revealed that the ITB attached in 34 of 36 patients and the capsule attached in 34 of 36 patients. One patient had only the capsule attached, another had only the ITB attached, and the last showed neither clearly attached. A literature review of 20 included studies revealed no difference between the previously described Segond fracture location and the tibial insertion of the ALL. Conclusion: The results of this study confirmed that while the Segond fracture occurs at the location of the tibial insertion of the ALL, as reported in the literature, MRI was unable to identify any distinct ligamentous attachment. MRI analysis revealed that soft tissue attachments to the Segond fracture were the posterior fibers of the ITB and the lateral capsule in 94% of patients.

Basic biomechanic principles of knee instability

Motion at the knee joint is a complex mechanical phenomenon. Stability is provided by a combination of static and dynamic structures that work in concert to prevent excessive movement or instability that is inherent in various knee injuries. The anterior cruciate ligament (ACL) is a main stabilizer of the knee, providing both translational and rotatory constraint. Despite the high volume of research directed at native ACL function, pathogenesis and surgical reconstruction of this structure, a gold standard for objective quantification of injury and subsequent repair, has not been demonstrated. Furthermore, recent studies have suggested that novel anatomic structures may play a significant role in knee stability. The use of biomechanical principles and testing techniques provides essential objective/quantitative information on the function of bone, ligaments, joint capsule, and other contributing soft tissues in response to various loading conditions. This review discusses the principles of biomechanics in relation to knee stability, with a focus on the objective quantification of knee stability, the individual contributions of specific knee structures to stability, and the most recent technological advances in the biomechanical evaluation of the knee joint.

Knee instability scores for ACL reconstruction

Despite abundant biological, biomechanical, and clinical research, return to sport after anterior cruciate ligament (ACL) injury remains a significant challenge. Residual rotatory knee laxity has been identified as one of the factors responsible for poor functional outcome. To improve and standardize the assessment of knee instability, a variety of instability scoring systems is available. Recently, devices to objectively quantify static and dynamic clinical exams have been developed to complement traditional subjective grading systems. These devices enable an improved evaluation of knee instability and possible associated injuries. This additional information may promote the development of new treatment algorithms and allow for individualized treatment. In this review, the different subjective laxity scores as well as complementary objective measuring systems are discussed, along with an introduction of injury to an individualized treatment algorithm.

Femoral neck fractures as a complication of hip arthroscopy: a systematic review

Abstract The purpose of this study was to identify the causes and risk factors for hip fractures, a rare but devastating complication, following hip arthroscopy. The electronic databases MEDLINE, EMBASE and PubMed were searched and screened in duplicate for relevant clinical and basic sciences studies and pertinent data was abstracted and analysed in Microsoft Excel. Nineteen studies (12 clinical studies and seven biomechanical studies) with a total of 31 392 patients experiencing 43 hip fractures (0.1% of patients) met the inclusion criteria for this systematic review. Femoral osteochondroplasty was performed in 100% of patients who sustained a hip fracture. Six of the 12 (50%) studies identified early weight bearing (prior to 6 weeks post-operatively) as the cause for the hip fracture. Other causes of this complication included over resection during femoral osteochondroplasty, minor trauma and intensive exercise. The results suggest that early weight bearing is the largest modifiable risk factor for hip fracture after femoral osteochondroplasty. For this reason, an extended period of non-weight bearing or restricted weight bearing should be considered in select patients. Studies report a correlation between risk for post-operative hip fracture and increased age. Increased resection during osteochondroplasty has been correlated with increased risk of fracture in various basic science studies. Resection depth has significantly higher impact on risk of fracture than resection length or width. The reported amounts of resection that depth that can be performed before there is a significantly increased risk of fracture of the femoral neck varies from 10 to 30%.

Kinematic outcomes following ACL reconstruction

Anterior cruciate ligament (ACL) reconstruction aims to restore the translational and rotational motion to the knee joint that is lost after injury. However, despite technical advancements, clinical outcomes are less than ideal, particularly in return to previous activity level. A major issue is the inability to standardize treatment protocols due to variations in materials and approaches used to accomplish ACL reconstruction. These include surgical techniques such as the transtibial and anteromedial portal methods that are currently under use and the wide availability of graft types that will be used to reconstruct the ACL. In addition, concomitant soft tissue injuries to the menisci and capsule are frequently present after ACL injury and, if left unaddressed, can lead to persistent instability even after the ACL has been reconstructed. Advances in the field of biomechanics that help to objectively measure motion of the knee joint may provide more precise data than current subjective clinical measurements. These technologies include extra-articular motion capture systems that measure the movement of the tibia in relation to the femur. With data gathered from these devices, a threshold for satisfactory knee stability may be established in order to correctly identify a successful reconstruction following ACL injury.

Passive teaching is not as effective as active teaching for learning the standard technique of pivot shift test

Objective Two major teaching methods available for learning the pivot shift test are active teaching with real-time feedback from an instructor and passive teaching through the use of instructional textbooks or videos. The purpose of this study was to determine the effect of active and passive teaching methods on the execution of the proper technique of the pivot shift test. Methods Six orthopaedic surgery residents each performed 110 pivot shift tests on a fresh-frozen, cadaveric pelvis-to-toe specimen with anterior cruciate ligament insufficiency and lateral meniscectomy. Participants performed 10 repetitions before teaching and a total of 100 repetitions after either active or passive teaching. Six degree-of-freedom kinematics of the knee defined by the Grood/Suntay coordinate system were recorded after every fifth repetition using an electromagnetic tracking system. Anterior/posterior translation of the lateral knee compartment during the reduction event was also quantified. Depending on the normality of the data, a two-tailed t-test or Wilcoxon rank-sum test was used for comparisons of kinematics between the active and passive teaching groups and between successful and unsuccessful trials within each teaching group. Statistical significance was set at p<0.05. Results The success rate after active teaching was 31.7% compared with 30.0% after passive teaching. However, the starting position of the reduction event in the active teaching group was rotated by more than twice the amount of valgus rotation compared with the passive group (7.4°±3.3° vs 3.0°±2.7°; p<0.001). During the reduction event, the active teaching group underwent 4.4°±5.6° of external rotation, which is 10.6° in the opposite direction of the passive group (6.2°±4.8° of internal rotation; p<0.001). Conclusion Successful pivot shift tests can be performed after passive teaching, but the standard technique is not as effectively learnt through passive teaching since traditional external rotation during the reduction event was not used as in the active teaching group. Level of evidence V.

Increased medial and lateral tibial posterior slopes are independent risk factors for graft failure following ACL reconstruction

PurposeTo analyze the contribution of increased lateral (LTPS) and medial tibial slopes (MTPS) as independent risk factors of graft failure following anterior cruciate ligament (ACL) reconstruction.Materials and methodsFifty-seven patients with graft failure after ACL reconstruction who underwent revision surgery between 2009 and 2014 were enrolled and matched to a control group of 69 patients with primary anatomic successful ACL reconstruction. Patients were matched based on age, sex, date of primary surgery and graft type. LTPS and MTPS were measured on MRI in a blinded fashion. Tibial and femoral tunnel positions were determined on CT scans. Independent t test was used to compare the MTPS and LTPS between subgroups. Risks of graft failure associated with an increasing MTPS and LTPS were analyzed using binary logistic analysis.ResultsThe means of LTPS (7.3°) and MTPS (6.7°) in the graft failure group were found to be significantly greater than in the control group (4.6° and 4.1°, respectively; p = < 0.001). Non-anatomic and anatomic tunnel positions were found in 42 cases (73.7%) and 15 cases (26.3%), respectively. There were no significant differences in MTPS or LTPS between patients with anatomic and non-anatomic tunnel positions within the graft failure group. An increase of the MTPS of 1° was associated with an 1.24 times increased likelihood of exhibiting graft failure [95% CI 1.07–1.43] (p = 0.003) and an increase of the LTPS of 1° was associated with an 1.17 times increased likelihood of exhibiting graft failure [95% CI 1.04–1.31] (p = 0.009). The increased risk was most evident in patients with a lateral tibial posterior slope of ≥ 10°.ConclusionsIncreased LTPS and MTPS are independent risk factors for graft failure following ACL reconstruction regardless whether tunnel position is anatomic or non-anatomic. This information may be helpful to clinicians when considering slope correction in selected revision ACL reconstruction procedures.

Differences between traumatic and non-traumatic causes of ACL revision surgery

PurposeThe purpose of this study was to evaluate and classify causes for anterior cruciate ligament (ACL) reconstruction failure. It was hypothesized that specific technical and biological reconstruction aspects would differ when comparing traumatic and non-traumatic ACL reconstruction failures.Materials and methodsOne hundred and forty-seven consecutive patients who experienced ACL reconstruction failure and underwent revision between 2009 and 2014 were analyzed. Based on a systematic failure analysis, including evaluation of technical information on primary ACL reconstruction and radiological assessment of tunnel positions, causes were classified into traumatic and non-traumatic mechanisms of failure; non-traumatic mechanisms were further sub-divided into technical and biologic causes. Spearman’s rank correlation coefficient and chi-squared tests were performed to determine differences between groups based on various factors including graft choice, fixation technique, technique of femoral tunnel positioning, tunnel malpositioning, and time to revision.ResultsNon-traumatic, i.e., technical, and traumatic mechanisms of ACL reconstruction failure were found in 64.5 and 29.1% of patients, respectively. Biological failure was found only in 6.4% of patients. Non-anatomical femoral tunnel positioning was found the most common cause (83.1%) for technical reconstruction failure followed by non-anatomical tibial tunnel positioning (45.1%). There were strong correlations between non-traumatic technical failure and femoral tunnel malpositioning, transtibial femoral tunnel drilling techniques, femoral transfixation techniques as well as earlier graft failure (p < 0.05).ConclusionsTechnical causes, particularly tunnel malpositioning, were significantly correlated with increased incidence of non-traumatic ACL reconstruction failure. Transtibial femoral tunnel positioning techniques and femoral transfixation techniques, showed an increased incidence of non-traumatic, earlier graft failure.