Posteromedial Bundle Research Articles

The lesion of anterior interosseous nerve syndrome is not in the forearm

The etiology of anterior interosseous nerve syndrome (AINS) is controversial, and ranges from compressive neuropathy in the forearm to spontaneous neuritis. Since the early 1990's, several series that report hourglass constriction (HGC) of the nerves in the upper extremity, including the anterior interosseous nerve (AIN) have been reported. The link between HGC and AINS has not been definitively resolved. We hypothesize that AINS is not a compressive or inflammatory lesion of the forearm, but rather a proximal intraneural disease of the postero-medial fascicle of the median nerve. This is a retrospective radiologic review of a consecutive series of 42 limbs in 40 patients with AINS in 2 academic centers in the United States and Hungary. The diagnosis of AIN palsy was strictly defined by complete clinical and electromyographic palsy of one or more muscles of the AIN. Each patient was evaluated with MRI, ultrasound or both by an expert neurodiagnostic imaging specialist. Five patients with recalcitrant disease were treated with interfascicular epi- and peri-neurolysis for failure to recover clinically or electrically after 12.4 months (range, 10 to 16 months). Twenty-nine patients had a characteristic pain prodrome of neuralgia amyotrophy (NA) that immediately preceded the onset of motor palsy. In 15 cases, the AIN was associated with palsy of additional median-innervated muscles, including the flexor carpi radialis, pronator, and/or palmaris longus. In 26 cases an ultrasound was performed and in 20 cases a MRI was performed. At least one hourglass constriction was identified in 25 patients, with a total of 42 constrictions reported. A fascicular swelling assessed with ultrasound or hyperintensity of the posteromedial fascicular bundle of the median nerve on MRI imaging was reported in eleven patients. In 71% of cases, the constriction was proximal to the medial epicondyle (mean 1.6 cm, from 0 to 18 cm) and in 29% the constriction was distal to the medial epicondyle (mean 1.3cm, from 0 to 3.5 cm). No extrinsic compression was identified in the forearm. Surgical exploration in 5 patients precisely corroborated imaging findings. Preoperative evaluation of AINS requires electromyographic confirmation, but advanced imaging has been discouraged [1] . Recent international studies have confirmed the value of MRI and ultrasonography to identify abnormalities of nerves affected by NA [2] , [3] . These data of 42 cases of AINS confirms that the disease is an intra-neural affectation of the median nerve (neuralgia amyotrophy) and not a compressive or inflammatory lesion of the AIN in the forearm. Intraneural disease of the posteromedial fascicular group of the median nerve is the primary pathology of AINS. We recommend that patients with AINS should undergo advanced imaging of the median nerve above and below the elbow by a specialist trained in imaging of the peripheral nerve.

What Kinds of Posterior Cruciate Ligament Bundles Are Preserved in Cruciate-Retaining Total Knee Arthroplasty? A Three-Dimensional Morphology Study.

In this study, the effects of tibial bone cutting on the attachment area of the posterior cruciate ligament (PCL), including both the anterolateral bundle (ALB) and posteromedial bundle (PMB), in cruciate-retaining total knee arthroplasty (CR-TKA) were simulated using a three-dimensional (3D) model of the tibial reconstruction. A total of 40 knees with medial osteoarthritis in patients scheduled for TKA were evaluated. Following surface registration of 3D computed tomography (CT) and 3D magnetic resonance imaging (MRI) models of the tibia with the PCL, the area of PCL attachment was calculated. Tibial bone cutting in the 3D CT model was simulated at 8 and 10 mm distal to the center of the lateral articular surfaces of the tibia and with posterior tibial slope angles of 0, 7, and 10 degrees. The percentages of the ALB and PMB tibial attachment areas that remained after cutting at 8 mm were, respectively, 21.8 ± 19.7% and 86.3 ± 17.7% with 0 degrees, 9.5 ± 10.4% and 64.1 ± 23.6% with 7 degrees, and 8.1 ± 6.7% and 51 ± 25.3% with 10 degrees. These results suggest that only half of the PCL attachment area was left after the bone cut simulation. Complete preservation of the ALB and PMB attachment areas requires appropriate selection of surgical procedures and devices.

Anatomic is better than isometric posterior cruciate ligament tunnel placement based upon in vivo simulation.

To elucidate the effects of various tibial and femoral attachment locations on the theoretical length changes and isometry of PCL grafts in healthy knees during in vivo weightbearing motion. The intact knees of 14 patients were imaged using a combined magnetic resonance and dual fluoroscopic imaging technique while the patient performed a quasi-static lunge (0°-120° of flexion). The theoretical end-to-end distances of the 3-dimensional wrapping paths between 165 femoral attachments, including the anatomic anterolateral bundle (ALB), central attachment and posteromedial bundle (PMB) of the PCL, connected to an anterolateral, central, and posteromedial tibial attachment were simulated and measured. A descriptive heatmap was created to demonstrate the length changes on the medial condyle and formal comparisons were made between the length changes of the anatomic PCL and most isometric grafts. The most isometric graft, with approximately 3% length change between 0° and 120° of flexion, was located proximal to the anatomic femoral PCL attachments. Grafts with femoral attachments proximal to the isometric zone decreased in length with increasing flexion angles, whereas grafts with more distal attachments increased in length with increasing flexion angles. The ALB and central single-bundle graft demonstrated a significant elongation from 0° to 120° of flexion (p < 0.001). The PMB decreased in length between 0° and 60° of flexion after which the bundle increased in length to its maximum length at 120° (p < 0.001). No significant differences in length changes were found between either the ALB or PMB and the central graft, and between the ALB and PMB at flexion angles ≥ 60° (n.s.). The most isometric attachment was proximal to the anatomic PCL footprint and resulted in non-physiological length changes. Moving the femoral attachment locations of the PCL significantly affected length change patterns, whereas moving the tibia locations did not. The importance of anatomically positioned (i.e., distal to the isometric area) femoral PCL reconstruction locations to replicate physiological length changes is highlighted. These data can be used to optimize tunnel positioning in either single- or double-bundle and primary or revision PCL reconstruction cases. IV.

Bicruciate lesion biomechanics, Part1-Diagnosis: translations over 15mm at 90° of knee flexion are indicative of a complete tear.

Understanding the pathomechanics of a bicruciate injury (BI) is critical for its correct diagnosis and treatment. The purpose of this biomechanical study aims to quantify the effects of sequential sectioning of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)bundles on knee laxity. Twelve cadaveric knees (six matched pairs) were used. Knee laxity measurements consisted of neutral tibial position, anterior-posterior translation, internal-external rotation, and varus-valgus angulation in different conditions: intact, ACL cut, incomplete BI (divided into two groups: anterolateral (AL) bundle intact or posteromedial (PM) bundle intact) and complete bicruciate tear. Data were collected using a Microscribe system at 0°, 30°, 60°, and 90° of knee flexion. In comparison to the intact knees, incomplete BI and complete BI showed a significant increase of total antero-posterior tibial translation. The largest significant increase was observed at 90° of flexion after a complete bicruciate resection (p < 0.001). A threshold difference greater than 15mm from the intact could be used to identify a complete BI from an incomplete BI evaluating the total antero-posterior translation at 90°. All sectioned states had significant increases compared with the intact condition in internal-external rotation and varus-valgus stability at all tested flexion angles. Both incomplete and complete BI led to an important AP translation instability at all angles; however, full extension was the most stable position at all injured models. Total antero-posterior translation at 90° of knee flexion over 15mm, in comparison to the intact condition, was indicative of a complete BI. Since the appropriate assessment of a combined ACL and PCL lesion remains a challenge, this study intends to assist its diagnosis. As BI's main antero-posterior instability occurred at 90°, a total antero-posterior drawer test is proposed to evaluate BI in the clinical setting. Total antero-posterior translation at 90° > 15mm, in comparison to the intact condition or the contra-lateral non-injured knee, can be used to identify a complete from an incomplete BI.

Posterior Cruciate Ligament: Anatomy and Biomechanics.

The purpose of this review is to present an in-depth look at the most recent literature regarding pertinent posterior cruciate ligament (PCL) anatomy and biomechanics. The PCL is an important restraint of posterior tibial translation relative to the femur. In addition, the PCL acts as a secondary restraint to resist varus, valgus, and external rotation moments about the knee. While less common than ACL injuries, injuries to the PCL can occur from a posterior force directed on the tibia, most common with the knee in a flexed position. The PCL is composed of two functional bundles and has important implications for knee stability. The anterolateral and posteromedial bundles have different patterns of tensioning throughout knee range of motion. The two bundles therefore contribute to resisting posterior tibial translation and rotation at different angles of knee flexion.

Thick graft vs. double-bundle technique on posterior cruciate ligament reconstruction: experimental biomechanical study with cadavers

ObjectiveTo evaluate the biomechanical effect of graft thickness compared to the double-bundle technique on posterior cruciate ligament (PCL) reconstruction in human cadaveric knees. MethodsNine human cadaveric knees were tested in five conditions: intact knee (INT), single-bundle reconstruction with a 10mm-quadriceps tendon (SB); double-bundle reconstruction with a 10mm-quadriceps tendon for the anterolateral bundle and a 7-mm doubled semitendinous tendon for the posteromedial bundle (DB); single-bundle reconstruction with a 10-mm quadriceps tendon plus a 7-mm doubled semitendinous tendon (SBT); and PCL-deficient (NoPCL). Posterior tibial translation (PTT) was measured in response to a 134N posterior tibial load at 0°, 30°, 60°, and 90° of knee flexion. ResultsThe PTT of the DB and SBT techniques was always significantly lower (better stability) than the PTT of the SB technique. The PTT of SBT technique was significantly lower than the PTT of the DB technique at 60° (p=0.005) and 90° (p=0.001). ConclusionsGraft enlargement improves knee stability in isolated PCL reconstructions, whereas the graft division in the two-bundle technique worsens this stability at 60° and 90° of knee flexion. The findings of this study suggest that knee stability in PCL reconstructions may be improved with the use of thicker grafts in a single-bundle technique rather than performing a double-bundle reconstruction.

Posterior Cruciate Ligament: Current Concepts Review.

The posterior cruciate ligament (PCL) is the largest and strongest ligament in the human knee, and the primary posterior stabilizer. Recent anatomy and biomechanical studies have provided an improved understanding of PCL function. PCL injuries are typically combined with other ligamentous, meniscal and chondral injuries. Stress radiography has become an important and validated objective measure in surgical decision making and post-operative assessment. Isolated grade I or II PCL injuries can usually be treated non-operatively. However, when acute grade III PCL ruptures occur together with other ligamentous injury and/or repairable meniscal body/root tears, surgery is indicated. Anatomic single-bundle PCL reconstruction (SB-PCLR) typically restores the larger anterolateral bundle (ALB) and represents the most commonly performed procedure. Unfortunately, residual posterior and rotational tibial instability after SB-PCLR has led to the development of an anatomic double-bundle (DB) PCLR to restore the native PCL footprint and co-dominant behavior of the anterolateral and posteromedial bundles and re-establish normal knee kinematics. The purpose of this article is to review the pertinent details regarding PCL anatomy, biomechanics, injury diagnosis and treatment options, with a focus on arthroscopically assisted DB-PCLR. Level of evidence: IV.

Anatomy of posterior cruciate ligament retained in a posterior cruciate ligament retaining total knee replacement: a cadaveric study.

Background: Recent evidence has highlighted a risk that the majority of posterior cruciate ligament (PCL) is removed while making bone cuts in tibia and femur during total knee replacement surgery. Aim of this cadaveric study is to calculate how much PCL footprint is retained in a PCL retaining prosthesis after routine tibial and femoral cuts are made. Methods: Twelve paired formalin-fixed Indian cadaveric knees were studied. Knees were disarticulated and all soft tissues were circumferentially removed from the tibia and femur. Footprints of antero-lateral and postero-medial bundles were marked on tibia and femur. Proximal tibial and distal femoral cuts were made using standard cutting jigs (Zimmer NexGen LPS). Digital photographs were taken with a magnification marker attached on the bone before and after making the cuts. Area of PCL insertion before and after the bone cuts was measured using software ImageJ (National Institute of Health).Results: Footprint on tibial side was reduced by 9.1%, and on femoral side by 21.8%. Footprint of AL bundle was reduced by 24.3% on the tibial side and by 15.3% on the femoral side. Footprint of PM bundle on tibia was not affected by the bone cut but was reduced by 18.5% on the femoral side.Conclusion: Tibial and femoral insertions of PCL are relatively well preserved after bone cuts are made in a posterior cruciate retaining TKR. There is differential sectioning of antero-lateral and postero-medial bundles of PCL on tibial and femoral sides.

It is feasible to perform an all-epiphyseal double-bundle posterior cruciate ligament reconstruction in skeletally immature patients? A computer-aided modelling study

ObjectiveThe purpose of this study was to determine whether damage to the physis, articular cartilage, medial collateral ligament (MCL) and medial patellofemoral ligament (MPFL) can be avoided during femoral tunnel drilling in an anatomic, all-epiphyseal double-bundle (DB) reconstruction of the posterior cruciate ligament (PCL) in the skeletally immature knee using three-dimensional (3D) reconstruction modelling.MethodsCT scans of eight male skeletally immature cadaveric knee specimens between the ages 5 and 11 years were used to create eight 3D models of paediatric femurs. Using these 3D models, 5 mm, 6 mm and 7 mm tunnels were placed in the anatomic footprints of the anterolateral (AL) and posteromedial (PM) bundles, simulating an outside-in technique. Both full-length and a predetermined socket length were simulated in various trajectories to achieve the following goals: (1) avoid the femoral physis and periphyseal ring; (2) create adequate spacing (≥2 mm) between the tunnels to avoid significant tunnel convergence in the PCL footprint; (3) avoid articular cartilage of trochlea and medial condyle; and (4) avoid the femoral origin of the MCL and MPFL.ResultsIn all eight models, both tunnels could be placed in the PCL origin without damaging the physis, articular cartilage, MCL or MPFL. There was an adequate bone bridge (≥2 mm) between the two tunnels in ages 7–11 with a 6–7 mm AL tunnel and a 5–6 mm PM tunnel, as well as the 5-year-old model, using a 6 mm and 5 mm AL and PM tunnel, respectively.ConclusionThis computer-aided design model demonstrated that 5 mm, 6 mm and 7 mm all-epiphyseal tunnels can be placed within the footprint of the PCL while avoiding direct injury to the femoral physis, articular cartilage, MCL and MPFL. By understanding the location and trajectory of tunnel and socket placement, DB PCL reconstruction may be performed in skeletally immature knees without causing damage to the distal femoral physis and surface ligament footprints.Level of evidenceIV.

Three-Dimensional Evaluation of Similarity of Right and Left Knee Joints.

PurposeThe purpose of this study was to evaluate the anatomical similarity of three-dimensional (3D) morphometric parameters between right and left knees.Materials and MethodsTen fresh-frozen paired cadaveric knees were tested. Following dissection, footprint areas of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were measured. Surface scanning was performed using a 3D scanner. Scanned data were reproduced and morphometric parameters were measured on specialized software. After making mirror models, we compared footprint center positions of the ACL and PCL of both sides and calculated the average deviation of 3D alignment between the right- and left-side models.ResultsNo significant side-to-side differences were found in any morphometric parameters. Bony shapes displayed a side-to-side difference of <1 mm. Distal femoral and proximal tibial volumes did not present side-to-side differences, either; the average 3D deviations of alignment between the right and left sides were 0.8±0.4/1.1±0.6 mm (distal femur/proximal tibia). Center-to-center distances between the right and left ACL footprints were 2.6/2.7 mm (femur/tibia) for the anteromedial bundle and 2.4/2.8 mm for the posterolateral bundle. They were 1.9/1.5 mm for the anterolateral bundle and 2.2/1.8 mm for the posteromedial bundle of the PCL.ConclusionsThere was a remarkable 3D morphometric similarity between right and left knees. Our results might support the concept of obtaining morphologic reference data from the uninvolved contralateral knee.

Transmedial All-inside TriLink Posterior Cruciate Ligament Reconstruction

Posterior cruciate ligament (PCL) injuries usually constitute part of a multiligament injury. Isolated PCL injuries account for only approximately 3% of all ligament injuries. No consensus on optimal surgical reconstruction exists. The PCL is a double-bundle structure that functions in an anisometric manner. Biomechanical studies have shown that re-creating the PCL femoral double-bundle configuration provides greater stability. We present a 3-socket approach for an anatomic “all-inside” double-bundle PCL reconstruction using our preferred option of a FiberTape (Arthrex, Naples, FL)–reinforced peroneus longus allograft fashioned to create a trifurcate graft: the TriLink technique. Cortical suspensory fixation devices are used, allowing differential tensioning of the anterolateral and posteromedial bundles. This enables more accurate replication of the native PCL and its biomechanical properties.

Double-bundle PCL Reconstruction: A Prospective Study of Two-year Patient Reported Outcomes with Stress Radiographs

Objectives:Reconstruction of grade-III posterior cruciate ligament (PCL) ruptures has historically been compromised by graft elongation and residual laxity. The purpose of this study was to report prospectively collected two-year outcomes and failure rates of double-bundle PCL reconstruction in a consecutive patient series with patient reported outcomes and quantitative stress radiographs. It was hypothesized that double bundle PCL reconstruction would result in improved subjective clinical outcomes, restoration of knee stability, and result in high patient satisfaction.Methods:A single surgeon consecutive series of patients that underwent double-bundle PCL reconstruction between June, 2010, and April, 2014, were followed prospectively. The technique is anatomically and biomechanically validated and utilizes two allografts (Achilles tendon for anterolateral bundle, tibialis anterior tendon for posteromedial bundle) in divergent femoral tunnels and a single tibial tunnel, each secured at the tibia at different knee angles to recreate the function of the two PCL bundles. Patient reported outcomes were collected preoperatively, and at a minimum two-year follow-up, including SF12, WOMAC, Tegner, Lysholm, and patient satisfaction. Posterior kneeling stress radiographs were obtained preoperatively and at the 6-month follow-up period. Failures were defined objectively as a difference of more than 3 mm in stress radiographs.Results:Sixty patients had greater than 2 year follow-up (mean 2.9 yrs). All subjective outcome measures improved except SF-12 mental component which was unchanged. The mean Lysholm score improved from 48 to 79. The mean WOMAC score improved from 39 to 11. The median SF-12 physical component score improved from 32 to 55. The median Tegner activity score improved from 2 to 5. The median patient satisfaction score was 8. Stress radiographs were available for 36 patients and improved from a preoperative side-to-side difference of 9.6 mm to 1.0 mm at 6 months follow-up. One failure occurred in a patient who had an 8 mm side-to-side difference at final follow-up and 18 mm pre-operatively.Conclusion:Double bundle PCL reconstruction results in improved patient reported outcomes and restoration of posterior knee stability. High patient satisfaction and low failure rates were found in this cohort of patients.

All-Inside Bicruciate Ligament Reconstruction Technique: A Focus on Graft Tensioning Sequence

Bicruciate ligament (BCL) reconstructions are challenging procedures. One of the main operative goals is to stabilize the knee in the correct anterior-posterior position. We present an all-inside arthroscopic BCL reconstruction technique using hamstring tendon grafts. Ipsilateral semitendinosus (ST) and gracilis tendons are used for TriLink (Arthrex, Naples, FL) double-bundle posterior cruciate ligament (PCL) reconstruction and contralateral ST tendon is used for GraftLink (Arthrex) single-bundle anterior cruciate ligament (ACL) reconstruction. The use of instruments for retrograde reaming and devices for adjustable cortical suspensory fixation allows for a safe, reproducible all-inside BCL reconstruction by simplifying these difficult steps. To minimize the risk of anterior-posterior malposition, the ACL graft is first tensioned with the knee in full extension, ensuring a neutral anteroposterior positioning of the tibia under the femur. The PCL anterolateral bundle can then be independently tensioned with the knee at 90° of flexion, and the posteromedial bundle at 30° of flexion, while applying an anterior translation to the tibia to reduce the posterior drawer without any risk of overcorrection. The purpose of this Technical Note was to describe an all-inside BCL reconstruction with a specific focus on the graft tensioning sequence.

Anatomic Double-Bundle Posterior Cruciate Ligament Reconstruction.

The posterior cruciate ligament (PCL) is the main posterior stabilizer of the knee. It is composed of 2 bundles, the larger anterolateral bundle (ALB) and the smaller posteromedial bundle (PMB). The 2 bundles were historically believed to function independently, with the ALB predominantly being an important stabilizer in flexion and the PMB being a stabilizer mainly in extension. However, a recent biomechanical study1 noted a codominant relationship between these 2 bundles. The anatomic single-bundle PCL reconstruction, focusing on reconstruction of the larger ALB, is the most commonly performed procedure. Because of the residual posterior and rotational tibial instability after a single-bundle reconstruction and the inability to restore the normal knee kinematics, an anatomic double-bundle PCL reconstruction has been proposed in an effort to recreate both bundles using the native footprint, thereby restoring the normal knee kinematics. The anatomic double-bundle PCL reconstruction has demonstrated improved subjective and objective patient outcomes with a low complication rate. Indications for PCL reconstruction are isolated symptomatic acute grade-III PCL tears, combined multiligament lesions, or acute grade-III PCL tears combined with repairable meniscal body or root tears. For chronic PCL tears, indications include functional limitations due to the PCL tear (e.g., difficulty with deceleration, incline descent, or stairs) and comparative PCL stress radiographic laxity of >8 mm in a symptomatic patient. The steps of this procedure include (1) correct patient positioning to allow for good accessibility of both sides of the joint; (2) graft preparation (Achilles tendon [ALB] and tibialis anterior [PMB] allografts are used); (3) creation of femoral tunnels (11 mm for the ALB adjacent to the cartilage and 7 mm for the PMB with a 2-mm bone bridge); (4) tibial tunnel creation (12-mm diameter, 7 mm anterior to the so-called champagne-glass drop-off); (5) graft fixation and tibial graft passage (a metal screw for the ALB and a bioabsorbable screw for the PMB, with the screws away from the bone bridge to avoid bone bridge breakage); and (6) tibial fixation (the grafts are independently fixed with the knee at 90° of flexion (ALB) and extension (PMB) with screws and washers on the medial side of the tibia. Three prospective randomized studies18,19,23 suggested that, while clinical outcomes are similar between both isolated transtibial reconstruction techniques, the objective measures of postoperative side-to-side posterior translation and objective International Knee Documentation Committee scores were significantly improved with double-bundle compared with single-bundle PCL reconstructions.

ANATOMICAL STUDY OF THE MORPHOMETRY OF THE TIBIAL AND FEMORAL ATTACHMENT SITES OF THE POSTERIOR CRUCIATE LIGAMENT; Estudio anatómico de la morfometría de los sitios de inserción tibial y femoral del ligamento cruzado posterior.

, Although later isolated injuries cruciate of the ligament (PCL) are managed through non-operative rehabilitation, reconstruction is becoming ITS anatomic increasingly important. This study Provides Information Regarding the position and variability of Its tibial attachment sites, dimensions of the femoral insertions, Between These Comparing males and females, and Between right and left knees. Thirty one cadaveric knees (15 right, 16 left) from nine female and seven male cadavers ( mean age 77 years) Were Examined. The PCL footprint Which was Identified from the mean length and width of the tibial anterolateral (AL) and posteromedial (PM) 8.7 and 10.9 mm Were bundles, and 7.3 and 13.44mm respectively. The mean length and width of the tibial footprint in males and females 10.2 and 10.3 mm Were, and 7.7 and 11.4 mm for the AL bundle and 8.2 and 14.2 mm and 12.9 mm and 6.7 for the PM bundle respectively. The mean anatomical position of the AL and 51.0% Were PM bundles and 50.0% of the mediolateral diameter of the tibial plateau. The mean lengths and widths of the PCL femoral attachment Were 9.4 mm and 12.8 for the AL bundle and 7.5 and 11.4 mm for the PM bundle, with the AL bundle attachment being Significantly larger (P = 0.034) in evils. No Difference between right and left knees Were Observed . The data presented here will aid in making decisions to Achieve Appropriate anatomic PCL reconstruction., Although isolated lesions of the posterior cruciate ligament (PCL) are Treated by non-operative rehabilitation, anatomical reconstruction've Become increasingly important. This study Provides information on the position and variability of the binding sites of the tibia, the dimensions of the femoral insertions, Comparing them Between the sexes, and Between the right and left knee. They Were Examined thirty-one (15 right and 16 left knees) of 9 women and 7 dead bodies of males (mean age 77 years). Brand LCP was Identified from the length and width anterolateral and posteromedial (PM) of the tibia (AL) Were the results 8.7 and 10.9 mm, and 7.3 and 13.44mm respectively. The average length and width of the mark of the tibia in the male and female Were 10.2 and 10.3 mm and 7.7 mm and 11.4 for fiber AL, 8.2 and 14.2 mm and 6.7 mm and 12.9 for PM, respectively fiber. The average anatomical position of the tendons AL and PM Were 51.0% and 50.0% of the mediolateral diameter of the tibial plateau. Half lengths and widths of the PCL femoral insertion Were 9.4 and 12.8 mm for the tendon AL and 7.5 and 11.4 mm for the PM tendon, tendon insertion site AL was Significantly higher (P = 0.034) in men. no Difference Between the right and left Knees Were Observed. The data presented here will help in the decision-PCL suitable for anatomical reconstruction decisions.

Loading Patterns of the Posterior Cruciate Ligament in the Healthy Knee: A Systematic Review.

BackgroundThe posterior cruciate ligament (PCL) is the strongest ligament of the knee, serving as one of the major passive stabilizers of the tibio-femoral joint. However, despite a number of experimental and modelling approaches to understand the kinematics and kinetics of the ligament, the normal loading conditions of the PCL and its functional bundles are still controversially discussed.ObjectivesThis study aimed to generate science-based evidence for understanding the functional loading of the PCL, including the anterolateral and posteromedial bundles, in the healthy knee joint through systematic review and statistical analysis of the literature.Data sourcesMEDLINE, EMBASE and CENTRALEligibility criteria for selecting studiesDatabases were searched for articles containing any numerical strain or force data on the healthy PCL and its functional bundles. Studied activities were as follows: passive flexion, flexion under 100N and 134N posterior tibial load, walking, stair ascent and descent, body-weight squatting and forward lunge.MethodStatistical analysis was performed on the reported load data, which was weighted according to the number of knees tested to extract average strain and force trends of the PCL and identify deviations from the norms.ResultsFrom the 3577 articles retrieved by the initial electronic search, only 66 met all inclusion criteria. The results obtained by aggregating data reported in the eligible studies indicate that the loading patterns of the PCL vary with activity type, knee flexion angle, but importantly also the technique used for assessment. Moreover, different fibres of the PCL exhibit different strain patterns during knee flexion, with higher strain magnitudes reported in the anterolateral bundle. While during passive flexion the posteromedial bundle is either lax or very slightly elongated, it experiences higher strain levels during forward lunge and has a synergetic relationship with the anterolateral bundle. The strain patterns obtained for virtual fibres that connect the origin and insertion of the bundles in a straight line show similar trends to those of the real bundles but with different magnitudes.ConclusionThis review represents what is now the best available understanding of the biomechanics of the PCL, and may help to improve programs for injury prevention, diagnosis methods as well as reconstruction and rehabilitation techniques.

Microstructural and Mechanical Properties of the Posterior Cruciate Ligament: A Comparison of the Anterolateral and Posteromedial Bundles.

The microstructural organization (collagen fiber alignment) of the posterior cruciate ligament (PCL), which likely corresponds with its functional properties, has only been described qualitatively in the literature, to our knowledge. The goal of this study was to quantify the tensile mechanical and microstructural properties of the PCL and compare these qualities between the anterolateral and posteromedial bundles. Twenty-two knee specimens from 13 donors (8 male and 5 female; mean age [and standard deviation] at the time of death, 43.0 ± 4.1 years; mean body mass index, 30.0 ± 6.7 kg/m2) were dissected to isolate the PCL, and each bundle was split into 3 regions. Mechanical testing of each regional sample consisted of preconditioning followed by a ramp-and-hold stress-relaxation test and a quasi-static ramp-to-failure test. Microstructural analysis was performed with use of a high-resolution, division-of-focal-plane polarization camera to evaluate the average direction of collagen orientation and the degree to which the collagen fibers were aligned in that direction. Results were compared between the anterolateral and posteromedial bundles and across the regions of each bundle. The anterolateral and posteromedial bundles demonstrated largely equivalent mechanical and microstructural properties. Elastic moduli in the toe and linear regions were not different; however, the posteromedial bundle did show significantly more stress relaxation (p = 0.004). There were also few differences in microstructural properties between bundles, which again were seen only in stress relaxation. Comparing regions within each bundle, several mechanical and microstructural parameters showed significant relationships across the posteromedial bundle, following a gradient of decreasing strength and alignment from anterior to posterior. The PCL has relatively homogenous microstructural and mechanical properties, with few differences between the anterolateral and posteromedial bundles. This finding suggests that distinct functions of the PCL bundles result primarily from size and anatomical location rather than from differences in these properties. These properties of the PCL can be used to assess the utility of graft choices and operative techniques for PCL reconstruction and may partly explain limited differences in the outcomes of single-bundle compared with double-bundle reconstruction techniques for the PCL.

Dynamic Evaluation of Pivot-Shift Phenomenon in Double-Bundle Anterior Cruciate Ligament Reconstruction Using Triaxial Accelerometer

To evaluate the effect of initial graft tension on rotational stability and to determine the minimum required tension (MRT) based on the pivot-shift phenomenon in isolated anteromedial bundle (AMB), isolated posteromedial bundle (PLB), and double-bundle anterior cruciate ligament (ACL) reconstructions using a triaxial accelerometer during surgery. Primary double-bundle ACL reconstructions were included. The pivot-shift test and N-test were performed before and during surgery with the acceleration measurements using a triaxial accelerometer. The pivot-shift test was also manually graded. The AMB and PLB were fixed to a graft tensioning system during surgery with the following settings: (1) AMB only (AMB), (2) PLB only (PLB), and (3) AMB and PLB (A+P). The total graft tension was first set at 20N and then was increased in increments of 10N until the pivot-shift test became negative, which was defined as the MRT in each setting. Twenty-five patients were evaluated. The MRT in the AMB setting averaged 26N (range, 20 to 40N); in the PLB setting, 28N (range, 20 to 40N); and in the A+P setting, 24N (range, 20 to 40N). The MRT in the A+P setting was significantly smaller than that in the PLB setting (P= .008). The acceleration in the A+P setting was significantly smaller than that in the AMB and PLB settings both in the pivot-shift test (vs AMB: P= .007, vs PLB: P=.011) and in the N-test (vs AMB: P < .001, vs PLB: P < .001). Double-bundle ACL reconstruction better controlled rotational stability with smaller MRT than isolated PLB reconstruction at the time of surgery. In double-bundle reconstruction, the MRT based on the pivot-shift phenomenon could be larger than previously reported MRT based on anteroposterior laxity. Level IV, therapeutic case series.

In vivo posterior cruciate ligament elongation in running activity after anatomic and non-anatomic anterior cruciate ligament reconstruction.

The goals of this study were to (1) investigate the in vivo elongation behaviour of the posterior cruciate ligament (PCL) during running in the uninjured knee and (2) evaluate changes in PCL elongation during running after anatomic or non-anatomic anterior cruciate ligament (ACL) reconstruction. Seventeen unilateral ACL-injured subjects were recruited after undergoing anatomic (n=9) or non-anatomic (n=8) ACL reconstruction. Bilateral high-resolution CT scans were obtained to produce 3D models. Anterolateral (AL) and posteromedial (PM) bundles insertion sites of the PCL were identified on the 3D CT scan reconstructions. Dynamic knee function was assessed during running using a dynamic stereo X-ray (DSX) system. The lengths of the AL and PM bundles were estimated from late swing through mid-stance. The contralateral knees served as normal controls. Control knees demonstrated a slight decrease in AL bundle and a significant decrease in PM bundle length following foot strike. Length and elongation patterns of the both bundles of the PCL in the anatomic ACL reconstruction group were similar to the controls. However, the change in dynamic PCL length was significantly greater in the non-anatomic group than in the anatomic reconstruction group after foot strike (p<0.05). The AL bundle length decreased slightly, and the PM bundle length significantly decreased after foot strike during running in uninjured knees. Anatomic ACL reconstruction maintained normal PCL elongation patterns more effectively than non-anatomic ACL reconstruction during high-demand, functional loading. These results support the use of anatomic ACL reconstruction to achieve normal knee function in high-demand activities. Case-control study, Level III.

Differences of Intra-Articular Graft Length between Sandwich-Style Reconstruction and Zhao-Style Non-Remnant-Preserving Double-Bundle Reconstruction of Posterior Cruciate Ligament.

Appropriate graft length within the joint and inside the osseous tunnel is essential for achieving posterior stability and adequate anchorage strength. Because of the curving path and thickness of the graft in double-bundle posterior cruciate ligament (PCL) reconstruction, especially in double-bundle PCL augmentation (with remnant preservation), the actual intra-articular length of PCL grafts, which remains unknown, may be longer than previously published values. The main purpose of the current study is to measure the actual intra-articular graft length required in sandwich-style PCL reconstruction (remnant-preserving double-bundle PCL augmentation) and Zhao-style non-remnant-preserving double-bundle PCL reconstruction (semi-anatomic double-bundle PCL reconstruction using double-double tunnel with tibial medial and lateral arrangement). Nine matched pairs of intact cadaveric knees were randomized between two groups and respectively received sandwich-style PCL reconstruction (remnant-preserving group) and Zhao-style non-remnant-preserving double-bundle PCL reconstruction (non-remnant-preserving group). The tunnel positions were exactly the same in two groups. The anterolateral (AL) bundle was reconstructed with four-stranded semitendinosus tendon, and the posteromedial (PM) bundle was reconstructed with four-stranded gracilis tendon. For each bundle, the length of the graft portion within the joint was measured. The current study indicated that in remnant-preserving group, the average intra-articular exposed portion was 42.0 mm (SD, 1.3 mm; range, 40.0 mm to 43.4 mm) for the AL bundle and 32.5 mm (SD, 2.9 mm; range, 27.8 mm to 35.8 mm) for the PM bundle. In non-remnant-preserving group, the intra-articular exposed portion was 34.5 mm (SD, 1.0 mm; range, 32.7 mm to 36.0 mm) for the AL bundle and 29.1 mm (SD, 2.1 mm; range, 25.2 mm to 31.9 mm) for the PM bundle. For both the AL and PM bundles, significant differences were found in average intra-articular graft length between the two groups. The current study, whose methodology is more rigorous and accurate by measuring the actual intra-articular graft length, has direct applications to clinical practice. When considering the total graft lengths during reconstruction, it is necessary to recognize that remnant PCL has a space occupation effect on graft and that remnant preservation requires longer intra-articular graft lengths than non-remnant preservation.