Anterior Cruciate Ligament Insertion Research Articles

Bone Density Distribution Pattern in the Lateral Wall of the Femoral Intercondylar Notch: Implications for the Direct Insertion of the Femoral ACL Attachment

Background: The ideal position of the femoral bone tunnel in the anterior cruciate ligament (ACL) is controversial. The functional importance of the ACL fiber varies depending on where it is attached to the femur. Functionally important fibers can cause high mechanical stress on the bone, and the Wolff law predicts that bone mineral density will increase at high mechanical stress sites. Purpose/Hypothesis: The purpose of this study was to use computed tomography imaging to determine the distribution pattern of bone density in the lateral intercondylar wall. It was hypothesized that the high-density area (HDA) of the lateral intercondylar wall would reflect the functional insertion of the ACL as reported in previous anatomic studies. Study Design: Descriptive epidemiology study. Methods: Data from 39 knees without ACL injuries were retrospectively collected. The HDA of the lateral intercondylar wall was defined as the region containing the top 10% of the radiodensity values. The shape of the HDA was approximated as an ellipse, and the quadrant method was used to determine the center of the ellipse. The association between the ratio of the minor axis to the major axis of the ellipse and background characteristics was investigated. Results: According to the quadrant method, the center of the HDA ellipse was 33.6% in the deep-shallow direction and 23.4% in the high-low direction. The center of the ellipse was comparable to the anatomic center of the ACL footprint, as previously reported. The ratio of the minor axis to the major axis of the ellipse was 0.58 (95% CI, 0.54-0.62). There was a significant negative correlation between the ratio of the minor axis to the major axis of the HDA ellipse and the posterior tibial slope ( r = −0.38, P = .02). Conclusion: The center of the HDA ellipse was found to be similar to the anatomic center of the ACL footprint. Considering the mechanical stress responses in bone, the HDA of the lateral intercondylar wall has the potential to represent the ACL insertion, especially functional insertion.

Anterior Cruciate Ligament Reconstruction: 3-Incision Technique With Allograft Quad Tendon ACL Reconstruction

Background: Anterior cruciate ligament (ACL) ruptures are becoming more common in younger and older athletes. Approximately 250,000 ACL injuries occur each year, requiring the need for an effective and reproducible surgical technique. Indications: The 3-incision outside-in technique utilizes the donor quadriceps tendon, an extraordinarily strong graft, without damage from autogenous harvesting of patellar tendon or hamstrings. While some data suggest higher re-rupture risk with donor tissue, this is counterbalanced by avoiding secondary surgical site damage. Technique Description: The ruptured ACL is removed and the intercondylar notch is cleaned to visualize the anatomical ACL insertion site. Using the 3-tunnel technique a gaff is passed through the intercondylar notch, through a puncture hole (incision 1) and a rear entry guide hooked to its tip. The guide point is pulled into the knee and placed in posterior aspect of the anatomic footprint of the native ACL. Through incision 2, a guide pin is drilled to this point and overdrilled with a 10-mm drill. The edges of the hole in the intercodylar notch are smoothed with a currette. The tibial footprint is cleared, a tibial aiming guide placed. Through incision 3, a guide pin is placed and over drilled with a 10-mm drill followed by a Gore-Tex reamer to ensure no impingement would inhibit graft passage. The proximal bone of a quadriceps tendon graft is sized through a 10-mm sizer and compacted. Two holes are drilled to hold sutures for the proximal aspect of the femoral graft. The quadriceps tendon graft is sized to fit through a 9-mm tunnel and the free end whipped with a stitch before being passed from outside-in through the smoothed tunnels. The femoral bone block is tapped to have a press fit initially and then is fixed with a Milagro screw. The knee is cycled ten times to remove slack and the interference fit guide pin is placed on the anterior aspect of the graft, and fixed with the knee at 15° to 30° of flexion. Stability is tested with confirmation of no impingement, and then an extra-articular reconstruction with a semitendinosus allograft is performed. The extra articular reconstruction is placed at the point between Gerdy's tubercle and the fibular head, passed under the skin and the iliotibial band, and then inserted just anterior and superior to the ACL femoral drill hole. Results: Patient outcomes in our initial experience are comparable to our autogenous bone-tendon-bone (BTB) procedures without anterior knee pain. Return to sport is similar with autogenous procedures, with a delay of 6 to 12 months. In addition, there is a possibility for acceleration of healing with the addition of platelet-rich plasma and hyaluronic acid between 1 and 3 months postsurgery. We have insufficient data so far to determine if the re-rupture rate will decline compared with reported outcomes. Conclusion: The 3-incision technique with allograft quadriceps tendon for ACL reconstruction is a reproducible surgical technique that avoids harvest from the patient's own body. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Histological differences in cartilage layer growth at various tendon and ligament insertions in rabbits.

Objectives: Histological differences in cartilage layer growth in Achilles tendon (AT), quadriceps tendon (QT), patellar tendon (PT), and anterior cruciate ligament (ACL) insertion are unclear. Therefore, this study aimed to investigate the differences in cartilage layer growth in AT, QT, PT, and ACL insertions. Materials and Methods: Forty-eight male Japanese white rabbits were used. Six animals were euthanized at different stages (day 1 and 1, 2, 4, 6, 8, 12, and 24 weeks). Safranin O-stained glycosaminoglycan (GAG) production area, chondrocyte count, and insertion width were investigated. Results: A two-way analysis of variance (ANOVA) revealed a significant difference in the main effects of time and insertion for all parameters. In addition, the time × insertion interaction was significant. Multiple comparisons showed a significant difference between the ACL insertion and all other variables; however, the GAG production area was not significantly different for the QT, PT, and AT insertions. AT insertions were significantly different from all other groups; however, the number of chondrocytes and insertion width were not significantly different for ACL, QT, and PT insertions. Conclusion: Cartilage layer growth differed between the AT, QT, PT, and ACL insertions. The differences between the insertions may also be due to the differences in their structures, locations, and mechanical environments.

Comparative morphology of the cruciate ligaments: A radiological study.

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are important structures to maintain knee stability. The present study aimed to further enrich understandings of the morphology of the cruciate ligaments and explore the relationship between the diameter of ACL and PCL. This study collected valid MRI samples of 50 male and 50 female normal right knee joints and measured the diameter of each point of the ACL and PCL through the 3D Slicer. The diameter of the ACL in the sagittal MRI of the normal right knee joint was significantly different from the diameter of each point of the PCL. The average diameter of each point of the ACL was larger than the diameter of the corresponding point of the PCL. Males and females had statistical differences in their PCL origin point, PCL midpoint, ACL origin point, ACL midpoint, and ACL insertion point diameters under sagittal MRI examination. The average diameter of males was greater than the average diameter of females at the above corresponding sites. In sagittal MRI scans of the normal right knee joint, we observed that only the origin point of the PCL exhibited a moderate correlation with the midpoint and insertion point of the ACL in terms of their respective diameters. The correlation between diameters of normal ACL and PCL in knee joint MRI was moderate and may help clinicians determine appropriate graft for cruciate ligament reconstruction surgery quickly for severe cruciate ligament injuries.

The footprint of the anterior horn of medial meniscus: A novel and reliable landmark for the tibial vertical cut in Oxford mobile-bearing medial unicompartmental knee arthroplasty

BackgroundTibial vertical cut is crucial for rotational position and bony coverage in Oxford mobile-bearing medial unicompartmental knee arthroplasty (UKA). This study aimed to determine whether the footprint of the anterior horn of medial meniscus (FAM) is a reliable landmark for tibial vertical cut. MethodsThe FAM and the line through FAM and the edge of anterior cruciate ligament insertion (FAMA line) were identified by dissection five knee joint specimens. The angle between FAMA line and standard Akagi’s line was measured. From 2022 to 2023, 64 patients (74 knees) diagnosed as anteromedial osteoarthritis were included to undergo primary Oxford medial UKA by two surgeons (Group 1 and 2), using FAMA line as a landmark for tibial vertical cut. The anteroposterior (AP) length, mediolateral (ML) length of tibial cut and tibial prothesis were measured by vernier caliper. ML/AP ratio was also calculated, and data were compared intragroup and intergroup. Mediolateral position and external rotation of tibial components were assessed postoperatively. ResultsFAMA line was parallel to standard Akagi’s line. No significant differences were found in AP and ML lengths between tibial cut and tibial component (AP different value = 0.007 ± 0.154 cm, P = 0.674, ML different value = 0.020 ± 0.195 cm, P = 0.155). The ML/AP ratio was similar between the two groups (P = 0.141, 0.646, 0.255, 0.607, 0.384, size AA ∼ D). No significant difference was found in mediolateral position (0.87 ± 0.03 vs. 0.86 ± 0.03, P = 0.156) and external rotation (6.88 ± 2.08 vs. 6.68 ± 2.22, P = 0.746) of the tibial component between the two groups. ConclusionThe FAM is a reliable landmark for tibial vertical cut in Oxford UKA.

Influence de la protéine périostine sur le développement des couches de fibrocartilage de l’insertion du ligament croisé antérieur

BackgroundPeriostin (Postn) is thought to play a role in the formation of anterior cruciate ligament (ACL) insertion. However, the influence of Postn on the development of ACL insertion requires further understanding. This study aimed to clarify the influence of Postn on the development of fibrocartilage layers of ACL insertion. HypothesisWe hypothesized that Postn would influence the development of fibrocartilage layers of ACL insertion. Materials and methodsC57BL/6N wild-type (Postn+/+; n=54) and Postn knockout (Postn−/−; n=54) mice were used in this study. Six animals were euthanized at 1 d and 1, 2, 3, 4, 6, 8, 10, and 12 weeks of age in each group. The chondrocyte number, proliferation, apoptosis, safranin O-stained glycosaminoglycan (GAG) area, type II collagen staining area, tidemark length, and insertion width were evaluated. ResultsChondrocyte proliferation was high up to 2 weeks in Postn+/+, while low at age 1 d; it was, especially lower in Postn−/− than in Postn+/+ at age 1 d and 1 week. Chondrocyte apoptosis was high up to age 8 weeks in Postn+/+ and at 6 weeks in Postn−/−; it was especially higher in Postn−/− than in Postn+/+ at age 1 week. The GAG stained area was thickest for age 1 d to 4 weeks in Postn+/+ and for age 2 to 6 weeks in Postn−/−. The type II collagen staining area in Postn+/+ was thicker than that in Postn−/− at age 6 and 8 weeks. The tidemark length in Postn+/+ was longer than that in Postn−/− from age 8 to 12 weeks. The insertion width in Postn+/+ was longer than that in Postn−/− from age 1 to 3 weeks. DiscussionPostn decreased cell proliferation in the early postnatal phase and influenced the development of the fibrocartilage layer extracellular matrix of ACL insertion in mice. Postn may contribute to the development of methods for regeneration of the ACL insertion. Level of evidenceV; controlled laboratory study.

Acute Bone Loss and Infrapatellar Fat Pad Fibrosis in the Knee After an In Vivo ACL Injury in Adolescent Mice

Background: Young patients are 6 times more likely than adults to have a primary anterior cruciate ligament (ACL) graft failure. Biological factors (ie, tunnel osteolysis) may account for up to a third of these failures. Previous evaluations of patient ACL explants indicated significant bone loss within the entheseal regions. However, it remains unknown if the degree of bone loss within the ACL insertion regions, wherein ACL grafts are fixated, exceeds that of the femoral and tibial condylar bone. Hypothesis: Bone loss in the mineralized matrices of the femoral and tibial ACL entheses is distinct from that clinically reported across the whole knee after injury. Study Design: Controlled laboratory study. Methods: We developed a clinically relevant in vivo mouse ACL injury model to cross-sectionally track the morphological and physiological postinjury changes within the ACL, femoral and tibial entheses, synovial joint space, and load-bearing epiphyseal cortical and trabecular bone components of the knee joint. Right ACLs of 10-week-old C57BL/6J female mice (N = 75) were injured in vivo with the contralateral ACLs serving as controls. Mice were euthanized at 1, 3, 7, 14, or 28 days after injury (n = 12/cohort). Downstream analyses included volumetric cortical and trabecular bone analyses and histopathologic assessments of the knee joint after injury. Gait analyses across all time points were also performed (n = 15 mice). Results: The majority of the ACL injuries in mice were partial tears. The femoral and tibial cortical bone volumes were 39% and 32% lower, respectively, at 28 days after injury than those of the uninjured contralateral knees (P < .01). Trabecular bone measures demonstrated little difference between injured and control knees after injury. Across all bone measures, bone loss was similar between the injured knee condyles and ACL entheses. There was also significant inflammatory activity within the knee after injury. By 7 days after injury, synovitis and fibrosis were sigificantly elevated in the injured knee compared with the controls (P < .01), which corresponded with significantly higher osteoclast activity in bone at this time point compared with the controls. This inflammatory response signficantly persisted throughout the duration of the study (P < .01). The hindlimb gait after injury deviated from normal, but mice habitually loaded their injured knee throughout the study. Conclusion: Bone loss was acute and persisted for 4 weeks after injury in mice. However, the authors’ hypothesis was not confirmed, as bone quality was not significantly lower in the entheses compared with the condylar bone regions after injury. With relatively normal hindlimb loading but a significant physiological response after injury, bone loss in this model may be driven by inflammation. Clinical Relevance: There is persistent bone resorption and fibrotic tissue development after injury that is not resolved. Inflammatory and catabolic activity may have a significant role in the postinjury decline of bone quality in the knee.

Knee laxity after anterior tibial eminence fracture in children: A 35-case series

IntroductionAnterior tibial eminence (ATE) fractures are characterized by avulsion of the anterior cruciate ligament insertion. The aim of our study was to evaluate the long-term incidence of laxity and instability in the aftermath of these fractures. The secondary objective was to identify factors for instability. HypothesisATE fracture in children is responsible for laxity and instability in the medium and long term. Material and methodsThis retrospective, single-center study included 35 isolated fractures of the tibial intercondylar eminence during skeletal growth between January 2006 and January 2020. Analysis comprised demographics, laxity measured by GNRB™, range of motion and IKDC and Lysholm scores. Clinical reassessment was performed in 24 patients, the other 11 being interviewed by telephone. ResultsMean laxity on GNRB™ was 1.46mm, and 3 patients had>3mm differential with respect to the healthy knee. Mean IKDC score was 92.2 and mean Lysholm score 93.1. Four patients showed instability, 2 of whom required surgical management. There was no significant difference in occurrence of laxity according to fracture type or reduction quality. Mean follow-up was 5.9years (range, 1.1–14.8). DiscussionOur clinical and functional results were in accordance with the literature. The long-term clinical results were satisfactory. ATE fractures require long-term follow-up to screen for instability and laxity on GNRB™. Level of evidenceIV, retrospective study.

Therapeutic effect of two methods on avulsion fracture of tibial insertion of anterior cruciate ligament.

BACKGROUNDThe tibial stop of anterior cruciate ligament (ACL) is fan-shaped and attached to the medial groove in front of the intercondylar spine, which is located between the anterior horn of the medial and lateral meniscus. The incidence of this fracture is low previously reported, which is common in children and adolescents. With the increase of sports injury and traffic injury and the deepening of under-standing, it is found that the incidence of the disease is high at present.AIMTo explore the difference between open reduction and internal fixation with small incision and high-intensity non-absorbable suture under arthroscopy in the treatment of tibial avulsion fracture of ACL.METHODSSeventy-six patients with tibial avulsion fracture of anterior cruciate ligament diagnosed and treated in Guanyun County People's Hospital from April 2018 to June 2020 were retrospectively analyzed. According to the surgical methods, they were divided into group A (40 cases) and group B (36 cases). Patients in group A were treated with arthroscopic high-strength non-absorbable suture, and patients in group B were treated with small incision open reduction and internal fixation. The operation time, fracture healing time, knee joint activity and functional score before and after operation, and surgical complications of the two groups were compared.RESULTSThe operation time of group A was higher than that of group B, and the difference was statistically significant (P < 0.05); the fracture healing time of group A was compared with that of group B, and the difference was not statistically significant (P > 0.05); The knee joint function activity was compared between two groups before operation, 3 mo and 6 mo after operation, and the difference was not statistically significant (P > 0.05); the knee joint function activity of group A and group B at 3 mo and 6 mo after operation was significantly higher than that before operation (P < 0.05); the limp, support, lock, instability, swelling, upstairs, squatting, pain and Lysholm score were compared between the two groups before and 6 mo after operation, and the difference was not statistically significant (P > 0.05); the scores of limp, support, lock, instability, swelling, upstairs, squatting, pain and Lysholm in group A and group B at 6 mo after operation were significantly higher than those before operation (P > 0.05); the surgical complication rate of group A was 2.63%, which was lower than 18.42% of group B, and the difference was statistically significant (P > 0.05).CONCLUSIONBoth small incision open reduction and internal fixation and arthroscopic high-strength non-absorbable sutures can achieve good results in the treatment of anterior cruciate ligament tibial avulsion fractures. The operation time of arthroscopic high-strength non-absorbable sutures is slightly longer, but the complication rate is lower.

Revision Anterior Cruciate Ligament Reconstruction Using Bone Dowels

Background: Revision anterior cruciate ligament (ACL) reconstruction is technically challenging and may require the use of bone dowels in either 1 or 2 stages. Indications: The indications for bone dowels include tibial or femoral tunnel malposition or widening of the tunnels. In the patient case, the tibial tunnel aperture was positioned far medial to the native ACL insertion with a horizontal tunnel trajectory and the femoral tunnel was vertical. In addition, there was tunnel widening to 12 mm of both tibial and femoral tunnels. Technique Description: A bone-patellar tendon-bone autograft was harvested and diagnostic arthroscopy was performed. The previous tibial tunnel was sequentially reamed from 8 to 12 mm to adequately overdrill the previous widened tunnel. Next, the femoral tunnel was reamed to 12 mm in similar fashion. Using a tamp and guide pin, a 12 × 30-mm allograft bone dowel was then malleted into the femoral tunnel until it was flush with the medial aspect of the lateral femoral condyle. Another 12 × 30-mm bone dowel was then advanced into the tibial tunnel until it was just below the native articular margin. With the bone dowels securely in place, the ACL reconstruction using the harvested bone-patellar tendon-bone autograft was performed. Results: Werner et al reported a study of 12 patients who had excellent incorporation of femoral tunnel allograft bone dowels and comparable objective and subjective scoring to 2-stage techniques. Dragoo et al reported a study of 18 patients with tibial tunnel allograft bone dowels that demonstrated significant increases in patient-reported outcome measures and a significant decrease in tunnel widening. Discussion/Conclusion: Revision ACL reconstruction may require bone dowels if there are malpositioned tunnels or if there is tunnel widening. Overall, the literature demonstrates that 1-stage revision outcomes have been comparable to reported 2-stage revision outcomes, both of which are satisfactory.

ACL Graft Matching: Cadaveric Comparison of Microscopic Anatomy of Quadriceps and Patellar Tendon Grafts and the Femoral ACL Insertion Site

Background: The optimal graft choice between the bone–patellar tendon–bone (BPTB) and the quadriceps tendon remains controversial. Studies evaluating the microscopic anatomy of the quadriceps tendon–patellar bone (QTB) and BPTB grafts for anterior cruciate ligament (ACL) reconstruction are currently lacking. Hypothesis: The relationship between post–ACL reconstruction graft bending angle (GBA) and the angle corresponding to the GBA (cGBA) would indicate that the BPTB can bend more than the QTB at the femoral tunnel aperture. Study Design: Controlled laboratory study. Methods: Twenty paired human cadaveric knees fixed at <10° of knee joint flexion (mean age, 82.5 years) underwent histological sectioning and staining with Masson trichrome and toluidine blue. The femoral ACL insertion, QTB graft, and BPTB graft were microscopically analyzed. The width of the direct insertion, thickness of the uncalcified fibrocartilage and calcified fibrocartilage, ligament attachment angle, and cGBA for each group were measured. Eighteen patients who underwent ACL reconstruction with QTB or BPTB autograft were included for the evaluation of GBA using computed tomography images at 1 week postoperatively. Results: The mean insertion widths of the femoral ACL, QTB, and BPTB were 7.81, 9.07, and 6.54 mm, respectively. The QTB was 16% wider than the ACL, while the BPTB was 16% narrower than the ACL. The mean insertion thicknesses of the femoral ACL, QTB, and BPTB were 0.53, 0.94, and 0.38 mm, respectively. The QTB was 77% thicker than the ACL (P < .001), while the BPTB was 28% thinner than the ACL (P = .017). The mean ligament attachment angles of the femoral ACL, QTB, and BPTB were 20.3°, 30.2°, and 33.3°, respectively, and the QTB and the BPTB were 49% and 64% larger, respectively, than the ACL. The mean cGBAs of the femoral ACL, QTB, and BPTB were 33.9°, 35.1°, and 12.3°, respectively. The BPTB was 64% smaller than the ACL, while there was no significant difference between the QTB and the ACL. The mean GBA was 57.7°. Conclusion: The insertion width and thickness were significantly greater and smaller in the QTB and BPTB grafts, respectively, than in the ACL. The relationship between GBA after ACL reconstruction and cGBA in knee extension indicates that at the femoral tunnel aperture, the BPTB can bend more than the QTB. Clinical Relevance: QTB graft may allow more anatomic ACL reconstruction to be performed.

Is Nonoperative Treatment Appropriate for All Patients With Type 1 Tibial Spine Fractures? A Multicenter Study of the Tibial Spine Research Interest Group.

Background:Type 1 tibial spine fractures are nondisplaced or ≤2 mm–displaced fractures of the tibial eminence and anterior cruciate ligament (ACL) insertion that are traditionally managed nonoperatively with immobilization.Hypothesis:Type 1 fractures do not carry a significant risk of associated injuries and therefore do not require advanced imaging or additional interventions aside from immobilization.Study Design:Case series; Level of evidence, 4.Methods:We reviewed 52 patients who were classified by their treating institution with type 1 tibial spine fractures. Patients aged ≤18 years with pretreatment plain radiographs and ≤ 1 year of follow-up were included. Pretreatment imaging was reviewed by 4 authors to assess classification agreement among the treating institutions. Patients were categorized into 2 groups to ensure that outcomes represented classic type 1 fracture patterns. Any patient with universal agreement among the 4 authors that the fracture did not appear consistent with a type 1 classification were assigned to the type 1+ (T1+) group; all other patients were assigned to the true type 1 (TT1) group. We evaluated the rates of pretreatment imaging, concomitant injuries, and need for operative interventions as well as treatment outcomes overall and for each group independently.Results:A total of 48 patients met inclusion criteria; 40 were in the TT1 group, while 8 were in the T1+ group, indicating less than universal agreement in the classification of these fractures. Overall, 12 (25%) underwent surgical treatment, and 12 (25%) had concomitant injuries. Also, 8 patients required additional surgical management including ACL reconstruction (n = 4), lateral meniscal repair (n = 2), lateral meniscectomy (n = 1), freeing an incarcerated medial meniscus (n = 1), and medial meniscectomy (n = 1).Conclusion:The classification of type 1 fractures can be challenging. Contrary to prior thought, a substantial number of patients with these fractures (>20%) were found to have concomitant injuries. Overall, surgical management was performed in 25% of patients in our cohort.

Prospective study of functional outcome of arthroscopic suture pull out fixation of displaced tibial spine avulsion fracture

Background: Tibial eminence avulsion fractures commonly occur in children and adolescents aged between 8 and 14 years. A valgus-directed force associated with an external torsion when the knee is in hyperextension is the most frequently referred mechanism, which closely resembles the one for anterior cruciate ligament (ACL) tears. This happens because the epiphyseal ossification process reaches the tibial eminence only in late childhood or adolescence, leaving this area more vulnerable to tensile forces than the ACL itself. In adults, this lesion is rare and associated either with high- energy trauma, boot-induced injuries in skiers or forced internal rotation with a flexed knee. Avulsion fractures may either involve the intercondylar depression where the ACL insertion lies only or, less frequently, the entire tibial spine with medial and lateral plateau.Materials and Methods: From November 2019 to December 2020, an intervention clinical study was carried out at Sanjay Gandhi institute of trauma and orthopaedics, A number of 30 patients having avulsion tibial spine fracture classified Meyers & McKeever Type II, TYPE III and IV were involved in our study.Results: Fractures were united within 3 months after surgery in all 30 cases. The Lysholm score was improved to 98(98.17 ± 1.599). In 2 patients, post operative knee stiffness was noted and arthrolysis was done for the same. All patients returned to their pre-injury physical activities at the last follow-up. Conclusion: Arthroscopic suture pull-out fixation for type III and IV tibial spine avulsion results in excellent clinical and radiological outcomes in patients with open and closed physis without any significant complications.

Influence of periostin on the development of fibrocartilage layers of anterior cruciate ligament insertion

BackgroundPeriostin (Postn) is thought to play a role in the formation of anterior cruciate ligament (ACL) insertion. However, the influence of Postn on the development of ACL insertion requires further understanding. This study aimed to clarify the influence of Postn on the development of fibrocartilage layers of ACL insertion. HypothesisWe hypothesized that Postn would influence the development of fibrocartilage layers of ACL insertion. Materials and methodsC57BL/6N wild-type (Postn+/+; n=54) and Postn knockout (Postn−/−; n=54) mice were used in this study. Six animals were euthanized at 1 d and 1, 2, 3, 4, 6, 8, 10, and 12 weeks of age in each group. The chondrocyte number, proliferation, apoptosis, safranin O-stained glycosaminoglycan (GAG) area, type II collagen staining area, tidemark length, and insertion width were evaluated. ResultsChondrocyte proliferation was high up to 2 weeks in Postn+/+, while low at age 1 d; it was, especially lower in Postn−/− than in Postn+/+ at age 1 d and 1 week. Chondrocyte apoptosis was high up to age 8 weeks in Postn+/+ and at 6 weeks in Postn−/−; it was especially higher in Postn−/− than in Postn+/+ at age 1 week. The GAG stained area was thickest for age 1 d to 4 weeks in Postn+/+ and for age 2 to 6 weeks in Postn−/−. The type II collagen staining area in Postn+/+ was thicker than that in Postn−/− at age 6 and 8 weeks. The tidemark length in Postn+/+ was longer than that in Postn−/− from age 8 to 12 weeks. The insertion width in Postn+/+ was longer than that in Postn−/− from age 1 to 3 weeks. DiscussionPostn decreased cell proliferation in the early postnatal phase and influenced the development of the fibrocartilage layer extracellular matrix of ACL insertion in mice. Postn may contribute to the development of methods for regeneration of the ACL insertion. Level of evidenceV; controlled laboratory study.

Arthroscopic anatomy and pathoanatomy of anterior cruciate ligament ruptures: clinical study with 94 patients

Purpose: To arthroscopically evaluate the size variability of the Anterior cruciate ligament (ACL) insertion sites and to determine whether there are variations in rupture patterns of the two ACL bundles.&#x0D; Material and Methods: Ninetyfour patients undergoing ACL reconstruction between June 2008 and June 2009 were included inour study. The average age of the patients was 26.7 ± 8.3 years (range, 16–48 years). Only patients with an ACL rupture less than 120 days old were included as unpublished data revealed difficulty in distinguishing between AM and PL bundles in older ACL ruptures.&#x0D; Results: The femoral ACL insertion site length ranged from 11 to 20 mm (15.9 ± 2.2). On the tibial side, the length of the tibial ACL insertion site ranged from 9 to 20 mm (16.0 ± 2.1). On the femoral side, the width of the ACL insertion site ranged from 6 to 11 mm (8.3 ± 1.2). On the tibial side, the width of the entire ACL insertion site ranged from 6 to 12 mm (8.7 ± 1.1). The most frequent injury pattern was found to be the proximal rupture of both bundles; seen in 74 patients (78.7%).&#x0D; Conclusion: Both hypotheses were confirmed, and this may be clinically relevant in anatomic ACL reconstruction.

Influence of femoral tunnel exit on the 3D graft bending angle in anterior cruciate ligament reconstruction

PurposeTo quantify the influence of the femoral tunnel exit (FTE) on the graft bending angle (GBA) and GBA-excursion throughout a full range of motion (ROM) in single-bundle anterior cruciate ligament (ACL) reconstruction.MethodsThree-dimensional (3D) surface models of five healthy knees were generated from a weight-bearing CT obtained throughout a full ROM (0, 30, 60, 90, 120°) and femoral and tibial ACL insertions were computed. The FTE was simulated for 16 predefined positions, referenced to the Blumensaat's line, for each patient throughout a full ROM (0, 30, 60, 90, 120°) resulting in a total of 400 simulations. 3D GBA was calculated between the 3D directional vector of the ACL and the femoral tunnel, while the intra-articular ACL insertions remained unchanged. For each simulation the 3D GBA, GBA-excursion, tunnel length and posterior tunnel blow-out were analysed.ResultsOverall, mean GBA decreased with increasing knee flexion for each FTE (p < 0.001). A more distal location of the FTE along the Blumensaat's line resulted in an increase of GBA and GBA-excursion of 8.5 ± 0.6° and 17.6 ± 1.1° /cm respectively (p < 0.001), while a more anterior location resulted in a change of GBA and GBA-excursion of -2.3 ± 0.6° /cm (+ 0.6 ± 0.4°/ cm from 0–60° flexion) and 9.8 ± 1.1 /cm respectively (p < 0.001).Mean tunnel length was 38.5 ± 5.2 mm (range 29.6–50.5). Posterior tunnel blow-out did not occur for any FTE.ConclusionAiming for a more proximal and posterior FTE, with respect to Blumensaat’s line, reliably reduces GBA and GBA-excursion, while preserving adequate tunnel length. This might aid to reduce excessive graft stress at the femoral tunnel aperture, decrease femoral tunnel widening and promote graft-healing.Level of EvidenceIV

Using the Remnant Anterior Cruciate Ligament to Improve Knee Stability: Biomechanical Analysis Using a Cadaveric Model.

Background:Injured anterior cruciate ligament (ACL) tissue retains proprioceptive nerve fibers, vascularity, and biomechanical properties. For these reasons, remnant ACL tissue is often preserved during the treatment of ACL injuries.Purpose:To assess through a cadaveric model whether reorienting and retensioning the residual ACL via an osteotomy improves knee stability after partial ACL tear, with substantial remnant tissue and intact femoral and tibial attachments.Study Design:Controlled laboratory study.Methods:In 8 adult cadaveric knees, we measured anterior tibial translation and rotational laxity at 30° and 90° of flexion with the ACL in its native state and in 3 conditions: partial tear, retensioned, and ACL-deficient. The partial-tear state consisted of a sectioned anteromedial ACL bundle.Results:In the native state, the translation was 10 ± 2.7 mm (mean ± SD) at 30° of flexion and 8.4 ± 3.6 mm at 90° of flexion. Anterior translation of the knees in the partial-tear state (14 ± 2.7 mm at 30° and 12 ± 2.7 mm at 90°) was significantly greater than baseline (P < .001 for both). Translation in the ACL-retensioned state (9.2 ± 1.7 mm at 30° and 7.2 ± 2.1 mm at 90°) was significantly less than in the ACL-deficient state (P < .001 for both), and translation was not significantly different from that of the intact state. For ACL-deficient knees, translation (20 ± 4.3 mm at 30° and 16 ± 4.4 mm at 90°) was significantly greater than all other states (P < .001 for all). Although rotational testing demonstrated the least laxity at 30° and 90° of flexion in the retensioned and intact states and the most laxity in the ACL-deficient state, rotation was not significantly different among any of the experimental states.Conclusion:In a cadaveric model of an incomplete ACL tear, a reorienting and retensioning core osteotomy at the tibial insertion of the remnant ACL improved anteroposterior translation of the knee without compromising its rotational laxity.Clinical Relevance:The findings of this study support the concept of ACL tissue reorienting and retensioning in the treatment of ACL laxity as an area for future investigation.

Effect of Percentage of Femoral Anterior Cruciate Ligament Insertion Site Reconstructed With Hamstring Tendon on Knee Kinematics and Graft Force

Background: Previous studies have stated that closely matching the size of the anterior cruciate ligament (ACL) insertion site footprint is important for biomechanical function and clinical stability after ACL reconstruction. However, the ACL varies widely regarding the area of femoral insertion, tibial insertion, and midsubstance of ACL, and reconstructing the insertion site area with a uniform diameter graft can result in a cross-sectional area that is greater than that of the midsubstance of the native ACL. Therefore, understanding the effect of relative graft size in ACL reconstruction on knee biomechanics is important for surgical planning. Purpose: To assess how the percentage of femoral insertion site affects knee biomechanics in single- and double-bundle ACL reconstruction. Study Design: Controlled laboratory study. Methods: A total of 14 human cadaveric knees were scanned with magnetic resonance imaging and tested using a robotic system under an anterior tibial load and a combined rotational load. In total, 7 knee states were evaluated: intact ACL; deficient ACL; single-bundle ACL reconstruction with approximate graft sizes 25% (small), 50% (medium), and 75% (large) of the femoral insertion site; and double-bundle reconstruction of approximately 50% (medium) and 75% (large) of the femoral insertion site, based on the ratio of the cross-sectional area of the graft to the area of the femoral ACL insertion site determined by magnetic resonance imaging. Results: Anterior tibial translation was not significantly larger than the intact state in single-bundle and double-bundle medium graft reconstructions (P > .05) and was significantly greater in the single-bundle small graft reconstruction (P < .05). Anterior knee translation in single-bundle medium graft and large graft reconstructions was not statistically different (P > .05). In contrast, the anterior tibial translation for double-bundle large graft reconstruction was significantly smaller than for double-bundle medium graft reconstruction at low flexion angles (P < .05). The single-bundle small graft force was significantly different from the intact ACL in situ force (P < .05). The graft force with double-bundle large reconstruction was significantly greater than that with the double-bundle medium reconstruction (P < .05) but was not significantly different from that of the intact ACL (P > .05). Conclusion: Knee biomechanics with a single-bundle small graft tended to be significantly different from those of the intact knee. In the kinematic and kinetic data for the single- and double-bundle medium graft reconstruction, only the anterior translation at full extension for the single-bundle reconstruction was significantly different (lower) from that of intact knee. This was a time zero study. Clinical Relevance: This study can provide surgeons with guidance in selecting the graft size for ACL reconstruction.

Gender Differences of the ACL Insertion Sites

Background. The modern principles of reconstruction of the anterior cruciate ligament (ACL) and well-known surgical techniques do not take into account the peculiarities of the anatomical structure of the female knee. This happens due to insufficient substantiation that these peculiarities could influence the results of the treatment. The purpose of this study was to obtain new data on the structure of the areas of the ACL attachment, taking into consideration patient’s gender and the surgical anatomy. Material and Methods. 40 unpaired “fresh” anatomical preparations of the human female and male knees were studied. After preparation of the knee joints, the morphometry of the distal femoral epiphysis and the proximal tibial epiphysis was carried out by a digital sliding caliper according to 16 parameters. The shape, size, area, and the distance of the ACL attachment center from individual bone structures were assessed. The obtained data were correlated with the gender type of the knee structure. Results. The distal femoral epiphysis of the “female” type knee joint compared with the “male” type revealed the significant differences (p0.05) in the following parameters: the width of the condyles at the level of the transepicondylar line, the width of the intercondylar fossa, the length and height of the lateral condyle, and the ratio of the condyles width at the level of the transepicondylar line to the height of the lateral condyle. The tibial proximal epiphysis showed the gender differences in the articular surface frontal and sagittal dimensions, the width of the intercondylar eminence and the posterior slope of the tibial epiphysis articular surface. These features determined the different proportions of the female knee structure. The area of the anterior cruciate ligament femoral attachment and its center in the “female” type of structure were located 3 mm distal and 1.5 mm posteriorly (anteriorly and downwardly in arthroscopic imaging). The area of the tibial attachment of the same ligament and its center were localized 2 mm anteriorly in comparison with the “male” type structure. Conclusion. The discovered anatomical differences made it possible to distinguish the “female” and “male” types of the knee structure. The topography of the anterior cruciate ligament attachment areas is gender specific. This should be taken into account in the anatomical reconstruction of the ligament.

The natural orientation of the Anterior Cruciate Ligament compared to the tibial plateau on magnetic resonance imaging scans

PurposeRemnant preserving Anterior Cruciate Ligament (ACL) reconstruction requires the graft to be passed through the remnant ACL stump. This requires knowledge of the native alignment of the ACL. We investigated the alignment and orientation compared directly to the tibial plateau on Magnetic Resonance Imaging. We assessed if current equipment is adequate for anatomical reconstruction. Methods50 MRI scans with intact ACL and PCL were reviewed. Measurements were taken of; a) angle of ACL and tibial plateau in the sagittal plane, b) angle of ACL and tibial plateau in the coronal plane, c) position of ACL insertion into tibia as percentage of anterior-posterior width, d) position of ACL insertion into tibia as percentage of medio-lateral width. Statistical analysis included intra and interobserver agreement. Commonly used tibial guides were assessed for range of angles possible in use. ResultsThe mean results for each measurement (+/− standard deviation) were; a) 45°(4.4°), b) 69°(5.5°), c) 37.2%(5.5%) d) 47.4%(1.5%). Intra-observer and inter-observer reliability were measured with satisfactory values. Not all tibial guides were able to produce an angle <45°. ConclusionOur study is the first comparing the angle of inclination of the ACL directly with the tibial plateau. We demonstrate the angle in the sagittal plane is lower than reported previously. This data can be used in planning the tibial tunnel using remnant preserving techniques, to orientate in the natural alignment of the ACL. Not all reconstruction systems include options to align at the lower than previously thought natural angle of the ACL. Evidence levelIII.