Steven Claes

Anatomy of the anterolateral ligament of the knee

In 1879, the French surgeon Segond described the existence of a ‘pearly, resistant, fibrous band’ at the anterolateral aspect of the human knee, attached to the eponymous Segond fracture. To date, the enigma surrounding this anatomical structure is reflected in confusing names such as ‘(mid‐third) lateral capsular ligament’, ‘capsulo‐osseous layer of the iliotibial band’ or ‘anterolateral ligament’, and no clear anatomical description has yet been provided. In this study, the presence and characteristics of Segonds ‘pearly band’, hereafter termed anterolateral ligament (ALL), was investigated in 41 unpaired, human cadaveric knees. The femoral and tibial attachment of the ALL, its course and its relationship with nearby anatomical structures were studied both qualitatively and quantitatively. In all but one of 41 cadaveric knees (97%), the ALL was found as a well‐defined ligamentous structure, clearly distinguishable from the anterolateral joint capsule. The origin of the ALL was situated at the prominence of the lateral femoral epicondyle, slightly anterior to the origin of the lateral collateral ligament, although connecting fibers between the two structures were observed. The ALL showed an oblique course to the anterolateral aspect of the proximal tibia, with firm attachments to the lateral meniscus, thus enveloping the inferior lateral geniculate artery and vein. Its insertion on the anterolateral tibia was grossly located midway between Gerdys tubercle and the tip of the fibular head, definitely separate from the iliotibial band (ITB). The ALL was found to be a distinct ligamentous structure at the anterolateral aspect of the human knee with consistent origin and insertion site features. By providing a detailed anatomical characterization of the ALL, this study clarifies the long‐standing enigma surrounding the existence of a ligamentous structure connecting the femur with the anterolateral tibia. Given its structure and anatomic location, the ALL is hypothesized to control internal tibial rotation and thus to affect the pivot shift phenomenon, although further studies are needed to investigate its biomechanical function.

Outcome of a Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction Technique With a Minimum 2-Year Follow-up

Background: The anterolateral ligament has recently been identified as an important structure involved in rotational laxity after anterior cruciate ligament (ACL) rupture. Results of a combined ACL and anterolateral ligament (ALL) reconstruction technique have never been reported. Purpose: To report subjective and objective outcomes after combined ACL and minimally invasive ALL reconstruction with a minimum 2-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: A total of 92 patients underwent a combined ACL and ALL reconstruction. Indications for a combined procedure were associated Segond fracture, chronic ACL lesion, grade 3 pivot shift, high level of sporting activity, pivoting sports, and radiographic lateral femoral notch sign. Patients were assessed pre- and postoperatively with objective and subjective International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity scale. Instrumented knee testing was performed with the Rolimeter arthrometer. The Knee injury and Osteoarthritis Outcome Score (KOOS) was obtained at the last follow-up. Complications including graft failure or contralateral ACL rupture were also recorded. Results: The mean follow-up time was 32.4 ± 3.9 months. One patient (1.1%) was lost to follow-up, 1 patient (1.1%) suffered an ACL graft rupture, and 7 patients (7.6%) had a contralateral ACL rupture, leaving 83 patients for final evaluation. At the last follow-up, all patients had full range of motion. The Lysholm, subjective IKDC, and objective IKDC scores were significantly improved (all P < .0001). The Tegner activity scale at the last follow-up (7.1 ± 1.8) was slightly lower than before surgery (7.3 ± 1.7) (P < .01). The mean differential anterior laxity was 8 ± 1.9 mm before surgery and significantly decreased to 0.7 ± 0.8 mm at the last follow-up (P < .0001). Preoperatively, 41 patients had a grade 1 pivot shift, 23 had a grade 2, and 19 had a grade 3 according to the IKDC criteria. Postoperatively, 76 patients had a negative pivot shift (grade 0), and 7 patients were grade 1 (P < .0001). Conclusion: This study demonstrates that a combined reconstruction can be an effective procedure without specific complications at a minimum follow-up of 2 years. Longer term and comparative follow-up studies are necessary to determine whether these combined reconstructions improve the results of ACL treatment.

The Anterolateral Ligament An Anatomic, Radiographic, and Biomechanical Analysis

Background: Recent publications have described significant variability in the femoral attachment and overall anatomy of the anterolateral ligament (ALL). Additionally, there is a paucity of data describing its structural properties. Purpose: Quantitative data characterizing the anatomic and radiographic locations and the structural properties of the ALL may be used to guide graft selection and placement and to facilitate the future development of an evidence-based approach to ALL reconstructions. Study Design: Descriptive laboratory study. Methods: Identification of the ALL was performed by a combined outside-in and inside-out anatomic dissection of 15 nonpaired fresh-frozen cadaveric knees. Quantitative anatomic relationships were calculated using a 3-dimensional coordinate measuring device. Measurements on anteroposterior (AP) and lateral radiographs were obtained by use of a picture archiving and communications system program. Structural properties were characterized during a single pull-to-failure test using a tensile testing machine. All anatomic, radiographic, and biomechanical measurements were reported as mean values and 95% CIs. Results: The ALL was identified as a thickening of the lateral capsule coming under tension with an applied internal rotation at 30° of flexion. Its femoral attachment was located 4.7 mm (95% CI, 3.5-5.9 mm) posterior and proximal to the fibular collateral ligament attachment and coursed anterodistally to its anterolateral tibial attachment approximately midway between the center of the Gerdy tubercle and the anterior margin of the fibular head; the tibial attachment was located 24.7 mm (95% CI, 23.3-26.2 mm) and 26.1 mm (95% CI, 23.9-28.3 mm) from each structure, respectively. On the AP radiographic view, the ALL originated on the femur 22.3 mm (95% CI, 20.7-23.9 mm) proximal to the joint line and inserted on the tibia 13.1 mm (95% CI, 12.3-13.9 mm) distal to the lateral tibial plateau. On the lateral view, the femoral attachment was 8.4 mm (95% CI, 6.8-10.0 mm) posterior and proximal to the lateral epicondyle. The tibial attachment was 19.0 mm (95% CI, 17.1-20.9 mm) posterior and superior to the center of the Gerdy tubercle. The mean maximum load was 175 N (95% CI, 139-211 N) and the stiffness was 20 N/mm (95% CI, 16-25 N/mm). Failure occurred by 4 distinct mechanisms: ligamentous tear at the femoral (n = 4) or tibial (n = 1) attachment, midsubstance tear (n = 4), and bony avulsion of the tibial attachment (Segond fracture; n = 6). Conclusion: Defined ALL attachment locations can be reproducibly identified with intraoperative landmarks or radiographs. The biomechanical analysis suggests that most traditional soft tissue grafts are sufficient for ALL reconstruction. Clinical Relevance: The ALL was consistently found in all knees. Segond fractures appear to occur primarily from the avulsion of the ALL.

The “Ligamentization” Process in Anterior Cruciate Ligament Reconstruction: What Happens to the Human Graft? A Systematic Review of the Literature

Background: Surgical anterior cruciate ligament reconstruction using tendon grafts has become the standard to treat the functionally unstable anterior cruciate ligament–deficient knee. Although tendons clearly differ biologically from ligaments, multiple animal studies have shown that the implanted tendons indeed seem to remodel into a ligamentous “anterior cruciate ligament–like” structure. Purpose: The goal of this study was to systematically review the current literature on the “ligamentization” process in human anterior cruciate ligament reconstruction. Study Design: Systematic review. Methods: A computerized search using relevant search terms was performed in the PubMed, MEDLINE, EMBASE, and Cochrane Library databases, as well as a manual search of reference lists. Searches were limited to studies examining the healing of the intra-articular portion of the tendon graft based on biopsies of this graft obtained from a living human. Results: Four studies were determined to be appropriate for systematic review, none of them reaching a level of evidence higher than 3. All reports considered autografts. Biopsy specimens were evaluated by light or electron microscopy and analyzed for vascularization, cellular aspects, and appearance of extracellular matrix. All authors universally agreed that the tendon grafts survive in the intra-articular environment. Based on changes observed in the healing grafts with regard to vascularization, cellular aspects, and properties of the extracellular matrix, different chronologic stages in the ligamentization process were discerned. Conclusion: The key finding of this systematic review is that a free tendon graft replacing a ruptured human anterior cruciate ligament undergoes a series of biologic processes termed “ligamentization.” The graft seems to remain viable at any time during this course. Histologically, the mature grafts may resemble the normal human anterior cruciate ligament, but ultrastructural differences regarding collagen fibril distribution do persist. Different stages of the ligamentization process are described, but no agreement exists on their time frame. Problematic direct transmission of animal data to the human situation, the limited number of reports considering the ligamentization process in humans, and the potential biopsy sampling error attributable to superficial graft biopsies necessitate further human studies on anterior cruciate ligament graft ligamentization.

The Segond fracture: a bony injury of the anterolateral ligament of the knee.

PURPOSE The purpose of this study was to investigate the relation of the Segond fracture with the anterolateral ligament (ALL) of the knee. METHODS To identify the soft-tissue structure causative for the Segond fracture, a study was set up to compare anatomic details of the tibial insertion of the recently characterized ALL in cadaveric knees (n = 30) with radiologic data obtained from patients (n = 29) with a possible Segond fracture based on an imaging protocol search. The spatial relation of the ALL footprint with well-identifiable anatomic landmarks at the lateral aspect of the knee was determined, and this was repeated for the Segond fracture bed. RESULTS In all of the included cadaveric knees, a well-defined ALL was found as a distinct ligamentous structure connecting the lateral femoral epicondyle with the anterolateral proximal tibia. The mean distance of the center of the tibial ALL footprint to the center of the Gerdy tubercle (GT-ALL distance) measured 22.0 ± 4.0 mm. The imaging database search identified 26 patients diagnosed with a Segond fracture. The mean GT-Segond distance measured 22.4 ± 2.6 mm. The observed difference of 0.4 mm (95% confidence interval, -1.5 to 2.2 mm) between the GT-ALL distance and GT-Segond distance was neither statistically significant (P = .70) nor clinically relevant. CONCLUSIONS The results of this study confirmed the hypothesis that the ALL inserts in the region on the proximal tibia from where Segond fractures consistently avulse, thus suggesting that the Segond fracture is actually a bony avulsion of the ALL. CLINICAL RELEVANCE Although the Segond fracture remains a useful radiographic clue for indirect detection of anterior cruciate ligament injuries, the Segond fracture should be considered a frank ligamentous avulsion itself.

The Effectiveness of Preventive Programs in Decreasing the Risk of Soccer Injuries in Belgium National Trends Over a Decade

Background: Although characterized by a relatively high injury rate, soccer is the world’s most popular sport. In Belgium, the national Royal Belgian Football Association involves about 420,000 licensed players, whose injury reports are collected in a nationwide registry. Over a period of 10 years, the association has introduced the Fédération Internationale de Football Association preventive programs and has initiated a stringent postponement policy of competition in case of nonoptimal weather conditions. Hypothesis: The authors questioned whether these preventive programs effectively decreased the incidence of soccer-related injuries. Study Design: Descriptive epidemiology study. Methods: The authors compared the incidence, location, timing, and severity of all registered soccer injuries in Belgium during 2 complete seasons separated by a decade (1999-2000 vs 2009-2010). Results: A total of 56,364 injuries were reported, with an average of 6.8 injuries per 100 players per season. There was a 21.1% reduction in injury rate in the second season (rate ratio = 0.789; 95% confidence interval, 0.776-0.802), predominantly caused by a significant reduction in injuries during the winter period. In both seasons, an injury peak was noted during the first 3 months of the season. Recreational players had a higher risk for injury than national-level players (7.2 vs 4.4 injuries per 100 players per season; rate ratio = 1.64; 95% confidence interval, 1.59-1.69). The relative proportion of severe injuries was higher for female players and male youth players in general. Conclusion: The introduction of injury preventive programs has led to a significant reduction of soccer-related injuries, especially during the winter period. However, there is still room for improvement, and preventive programs can become more effective when specific parameters are targeted, such as adequate conditioning of players in the preseason.

Contributions of the anterolateral complex and the anterolateral ligament to rotatory knee stability in the setting of ACL Injury: a roundtable discussion

AbstractPersistent rotatory knee laxity is increasingly recognized as a common finding after anterior cruciate ligament (ACL) reconstruction. While the reasons behind rotator knee laxity are multifactorial, the impact of the anterolateral knee structures is significant. As such, substantial focus has been directed toward better understanding these structures, including their anatomy, biomechanics, in vivo function, injury patterns, and the ideal procedures with which to address any rotatory knee laxity that results from damage to these structures. However, the complexity of lateral knee anatomy, varying dissection techniques, differing specimen preparation methods, inconsistent sectioning techniques in biomechanical studies, and confusing terminology have led to discrepancies in published studies on the topic. Furthermore, anatomical and functional descriptions have varied widely. As such, we have assembled a panel of expert surgeons and scientists to discuss the roles of the anterolateral structures in rotatory knee laxity, the healing potential of these structures, the most appropriate procedures to address rotatory knee laxity, and the indications for these procedures. In this round table discussion, KSSTA Editor-in-Chief Professor Jón Karlsson poses a variety of relevant and timely questions, and experts from around the world provide answers based on their personal experiences, scientific study, and interpretations of the literature. Level of evidence V.

Postural stability deficits during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects.

The goal of this study was to evaluate postural stability during the transition from double-leg stance (DLS) to single-leg stance (SLS) in anterior cruciate ligament reconstructed (ACLR) (n=20) and non-injured control subjects (n=20). All ACLR subjects had fully returned to their pre-injury sport participation. Both groups were similar for age, gender, height, weight, body mass index and activity level. Spatiotemporal center of pressure outcomes of both legs of each subject were measured during the transition from DLS to SLS in eyes open and eyes closed conditions. Movement speed was standardized. The center of pressure displacement after a new stability point was reached during the SLS phase was significantly increased in the ACLR group compared to the control group in the eyes closed condition (P=.001). No significant different postural stability outcomes were found between the operated and non-operated legs. In conclusion, the ACLR group showed postural stability deficits, indicating that these persons may have a decreased ability to stabilize their body after the internal postural perturbation created by the transition from DLS to SLS. The non-operated leg may not be the best reference when evaluating postural stability of the operated leg after ACLR, as no differences were found between legs.

A three-dimensional classification for mathematical pore shape description in complex carbonate reservoir rocks

Porous carbonates display some of the most complex porosity networks in reservoir rocks. This requires a quantitative geometric description of the complex (micro)structure of the rocks. Modern computer tomography techniques permit acquiring detailed information concerning the porosity network in three dimensions. These datasets allow a more objective pore classification based on mathematical parameters. In this study, ratios of the longest, intermediate, shortest dimensions and compactness of the pore shapes, based on an approximating ellipsoid, are analysed to obtain a thorough and objective description of pore shapes. Using intrinsic properties of the latter, the classification can be used at every resolution scale. Five shape classes are defined: rod, blade, plate, cuboid and cube. An additional advantage of this classification is that the data provide information about the orientation of the pores. This allows assessing the anisotropy of the porosity parameter. Apart from having an objective pore-type classification, analysing the shape and orientation of the pores permits to study the relationship with other important petrophysical rock characteristics such as permeability, acoustic properties and rock mechanical behaviour.

The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee: Letter to the Editor

Dear Editor: We read with significant interest the article by Kittl et al on the role of the anterolateral structures in controlling laxity of the intact and anterior cruciate ligament (ACL)–deficient knee. We congratulate the authors on this interesting study, which contributes further to our understanding of the role of these anatomic structures. However, we would like to bring up some important questions and remarks related to this paper. First, has the dissection technique utilized in this study been previously validated? How did the authors confirm that they were isolating the deep iliotibial band (ITB) from the superficial ITB? Similarly, the isolation of the anterolateral ligament (ALL) performed in this study has never, to our knowledge, been performed in this way. How did the authors ensure that the deep capsule-osseous layer and the ALL were completely separated in their entirety? Was histologic analysis subsequently performed to ensure that each structure tested was as described? The ALL described in the article and illustrated in Figure 3 is visually quite different from the structure described in previous publications. The ALL depicted in Figure 3 of this article appears significantly smaller, with an attachment that appears to be adjacent to the joint line of the tibia, above the tibial landmarks previously described. Furthermore, the anatomic depiction lacks the fanlike insertion on the tibia that has been widely published. In addition, Figure 2B of the Kittl et al article demonstrates the knee after resection of the capsule-osseous layer of the ITB, prior to isolation of the ALL, yet there does not appear to be any distinguishable structure remaining, certainly not the presence of a robust ALL. We know that the dissection technique utilized contributes significantly to the interpretation of the characteristics of these anterolateral structures, specifically the ALL, and that this interpretation also alters the biomechanical characteristics of these structures. A review of articles by Kaplan and Terry et al reveals the historical challenge in defining these structures. It is interesting, however, that Terry et al describe the capsule-osseous layer of the deep ITB as a structure ‘‘whose proximal origin is continuous with fascia covering the plantaris and lateral gastrocnemius and whose tibial insertion is just posterior to the Gerdy tubercle.’’ Furthermore, Terry et al describe this structure as acting as if it is ‘‘an anterolateral ligament of the knee’’ (Figure 1). We postulate that perhaps the ‘‘deep capsulo-osseous layer of the ITB’’ referenced by Terry et al and the ALL of the knee are generally the same structure, just dissected with different techniques. Current literature clearly demonstrates that directly underneath the ‘‘superficial’’ ITB lies the ALL, as demonstrated not only by the dissection technique from Daggett et al but also by magnetic resonance imaging studies showing that the ALL runs inferior to the ITB with no other distinguishable structure between them. Additionally, we know that this structure is histologically an extracapsular ligament and is involved in rotational control of the knee. The correlation between the ALL and the ‘‘capsulo-osseous layer of the ITB’’ as described by Terry et al is further supported by biomechanical findings. When the findings of this study by Kittl et al are compared with those of other studies examining the role of the ALL in internal rotation control of the tibia, the results are quite similar if one considers the structures to be the same. Regardless of name, we are now all in agreement that an anatomic structure, deep to the superficial ITB that inserts posterior to the Gerdy tubercle, plays a significant role in controlling internal rotation of the knee. Furthermore, while the authors found a significant contribution of the ‘‘superficial’’ ITB to stability of the knee, we believe that these laboratory findings do not translate clinically. In the setting of acute ACL tear, one rarely encounters an injury to the ITB. Additionally, although the authors found the different structures contributing to rotation at varying degrees of flexion, physiologic motion of the knee in its entirety is what is important, and this motion is limited internal rotation toward knee extension (ie, 15 ) with significantly more physiologic rotation in deeper degrees of knee flexion (ie, 90 ). Figure 1. The capsulo-osseous layer of the iliotibial band as described by Terry et al demonstrates significant similarity to the anterolateral ligament as described by Claes et al. (Reprinted with permission from Terry et al. 1986, American Orthopaedic Society for Sports Medicine.)