Posterolateral reconstruction using split achilles tendon allograft

Injury to the cruciate ligaments of the knee commonly occurs in association with posterolateral instability, which can cause severe functional disability including varus, posterior translation, and external rotational instability. Failure to diagnose and treat an injury of the posterolateral corner in a patient who has a tear of the cruciate ligament can also result in the failure of the reconstructed cruciate ligament. Unlike isolated posterior cruciate ligament injury, there seems to be a consensus of opinion that injury to the posterolateral corner, whether isolated or combined, is best treated by reconstructing the posterolateral corner along with the coexisting cruciate ligament injury, if combined. Commonly proposed methods of reconstructing the posterolateral corner have focused on the reconstruction of the popliteus, the popliteofibular ligament, and the lateral collateral ligament. We introduce a new technique for reconstructing the posterolateral corner using a split Achilles tendon allograft. Our method reasonably addresses the several pitfalls in the reconstruction of the posterolateral corner, including (1) concurrent reconstruction of important posterolateral structures, (2) regaining the isometry of the lateral collateral ligament, (3) repositioning the reconstructed popliteus into its original position, and (4) providing a secure fixation method.     

In situ forces in the posterolateral structures of the knee under posterior tibial loading in the intact and posterior cruciate ligament-deficient knee

The posterolateral structures of the knee consist of a complex anatomical architecture that includes several components with both static and dynamic functions. Injuries of the posterolateral structures occur frequently in conjunction with ruptures of the posterior cruciate ligament. To investigate the role of the posterolateral structures in maintaining posterior knee stability, we measured the in situ forces in the posterolateral structures and the distribution of force within the structures major components, i.e., the popliteus complex and the lateral collateral ligament, in response to a posterior tibial load. Eight cadaveric knees were tested. With use of a robotic/universal force-moment sensor testing system, a posterior tibial load of 110 N was applied to the knee, and the resulting five-degree-of-freedom kinematics were measured at flexion angles of 0, 30, 60, 75, and 90°. The knees were tested first in the intact state and then after the posterior cruciate ligament had been resected. These tests were also performed with an additional load of 44 N applied at the aponeurosis to simulate contraction of the popliteus muscle. In the intact knee, the in situ forces in the posterolateral structures were found to decrease with increasing knee flexion. After the posterior cruciate ligament was sectioned, these forces increased significantly at all angles of flexion. With no load applied to the popliteus muscle, the in situ forces in the popliteus complex were similar to those in the lateral collateral ligament. However, with a load of 44 N applied to the popliteus muscle, in situ forces in the popliteus complex were three to five, times higher than those in the lateral collateral ligament. These results reveal that in response to posterior tibial loads, the posterolateral structures play an important role at full extension in intact knees and at all angles of flexion in posterior cruciate ligament-deficient knees. The popliteus muscle appears to be a major stabilizer under this loading condition; thus, the inability to restore its function may be a cause of unsatisfactory results in reconstructive procedures of the posterolateral structures of the knee.     

Injuries of the posterolateral corner of the knee

The complex anatomy of the posterolateral corner of the knee is due largely to the evolutionary changes in the anatomic relationships of the fibular head, the popliteus tendon, and the biceps femoris muscle. Recent research has improved our understanding of the popliteus complex, particularly the role of the popliteofibular ligament. Biomechanical studies provide a scientific basis for clinical examination of the knee with suspected injury of the posterolateral corner. All grade-I and most moderate grade-II injuries of the posterolateral structures can be treated nonoperatively, but residual laxity may remain, especially in knees with grade-II injury. Acute grade-III isolated or combined injury of the posterolateral corner is best treated early, by direct repair, if possible, or else by augmentation or reconstruction of all injured ligaments. Chronic injury of the posterolateral corner, whether isolated or combined, is probably best treated by reconstruction of the posterolateral corner along with reconstruction of any coexisting cruciate ligament injury. Failure to diagnose and treat an injury of the posterolateral corner in a patient who has a known tear of the anterior or posterior cruciate ligament can result in failure of the reconstructed cruciate ligament.     

Anatomy and biomechanics of the posterolateral aspect of the canine knee.

The purpose of this study was to describe the anatomy and characterize the biomechanics of the posterolateral aspect of the canine knee. Ten adult canine knees were each used for anatomy and biomechanical testing. Distances and motion limits were measured using a 6 degree-of-freedom electromagnetic tracking system. Canine knee dissection reproducibly identified structures present in the human posterolateral knee. The course and attachment sites of the fibular collateral ligament, popliteofibular ligament, and popliteus tendon were similar to human anatomy. Sequential sectioning of the fibular collateral ligament, popliteofibular ligament, and popliteus tendon all significantly increased varus translation at full extension, 60 degrees , and 90 degrees of knee flexion. Sectioning of the fibular collateral ligament significantly increased external rotation at flexion angles near full extension, while popliteus tendon sectioning also significantly increased external rotation at 90 degrees of knee flexion. Based on the fact that the anatomy of the fibular collateral ligament, popliteus tendon, popliteofibular ligament, and the biomechanical properties of the canine posterolateral knee are similar to the human knee, we believe the canine knee is a suitable model to study the natural history of posterolateral knee injuries. The canine model will also prove valuable in the validation of reconstruction techniques and studying the potential development of medial compartment osteoarthritis following posterolateral knee injuries.     

The effect of isolated popliteus tendon complex injury on graft force in anterior cruciate ligament reconstructed knees

Failure to diagnose injury to the posterolateral structures has been found to increase the forces experienced by the anterior cruciate ligament (ACL) and ACL grafts which may cause their subsequent failure. An isolated injury to the popliteus complex (PC) consisting of the popliteus tendon and popliteofibular ligament is not uncommon. Therefore, the purpose of this study was to discover if an isolated injury to the PC can significantly affect the forces experienced by the ACL graft under external loading conditions. We hypothesised that, under external tibial torque, the ACL graft will experience a significant increase in force, in knees with PC injury compared to the intact PC condition. Under varus tibial torque (10 N m), we observed minimal changes in the varus tibial rotation due to isolated sectioning of the PC in an ACL reconstructed knee (P > 0.05). Consequently, no significant increase in the ACL graft force was observed under varus tibial torque. In contrast, sectioning the PC resulted in a significant increase in the external tibial rotation compared to the intact PC knee condition under the external rotational tibial torque (5 N m) at all flexion angles (P < 0.05). These changes in kinematics under external tibial torque were manifested as elevated ACL graft forces at all selected flexion angles (P < 0.05). Prompt diagnosis of isolated PC injury and its treatment are warranted to prevent potential failure of ACL reconstruction.     

Anterolateral rotational knee instability: role of posterolateral structures

Introduction The aim of this study was to determine the anterolateral rotational instability (ALRI) of the human knee after rupture of the anterior cruciate ligament (ACL) and after additional injury of the different components of the posterolateral structures (PLS). It was hypothesized that a transsection of the ACL will significantly increase the ALRI of the knee and furthermore that sectioning the PLS [lateral collateral ligament (LCL), popliteus complex (PC)] will additionally significantly increase the ALRI. Materials and methods Five human cadaveric knees were used for dissection to study the appearance and behaviour of the structures of the posterolateral corner under anterior tibial load. Ten fresh-frozen human cadaver knees were subjected to anterior tibial load of 134 N and combined rotatory load of 10 Nm valgus and 4 Nm internal tibial torque using a robotic/universal force moment sensor (UFS) testing system and the resulting knee kinematics were determined for intact, ACL-, LCL- and PC-deficient (popliteus tendon and popliteofibular ligament) knee. Statistical analyses were performed using a two-way ANOVA test with the level of significance set at P < 0.05. Results Sectioning the ACL significantly increased the anterior tibial translation (ATT) and internal tibial rotation under a combined rotatory load at 0 and 30° flexion (P < 0.05). Sectioning the LCL further increased the ALRI significantly at 0°, 30° and 60° of flexion (P < 0.05). Subsequent cutting of the PC increased the ATT under anterior tibial load (P < 0.05), but did not increase the ALRI (P > 0.05). Conclusion The results of the current study confirm the concept that the rupture of the ACL is associated with ALRI. Current reconstruction techniques should focus on restoring the anterolateral rotational knee instability to the intact knee. Additional injury to the LCL further increases the anterior rotational instability significantly, while the PC is less important. Cautions should be taken when examining a patient with ACL rupture to diagnose injuries to the primary restraints of tibial rotation such as the LCL. If an additional extraarticular stabilisation technique is needed for severe ALRI, the technique should be able to restore the function of the LCL and not the PC. This study is a winner of the AGA DonJoy Award 2006.     

Arthroscopic identification of the popliteofibular ligament

Purpose: The popliteofibular ligament has recently received recognition as a distinct structure with a significant contribution to posterolateral stability of the knee. The popliteofibular ligament plays a key role in stabilizing the posterolateral corner of the knee by limiting posterior translation, varus angulation, and external rotation (coupled and primary). During arthroscopic procedures, the senior author (R.D.P.) has observed vertically oriented fibers descending from the inferior surface of the intra-articular portion of the popliteus tendon at the popliteal hiatus. This study was performed to determine if these fibers were actually the popliteofibular ligament. Type of Study: This is an anatomic study using a cadaveric knee model to identify the popliteofibular ligament both arthroscopically and through gross anatomic dissection. Methods: Eight fresh human cadaveric knees were examined arthroscopically and the vertically oriented fibers from the inferior surface of the popliteus tendon at the popliteal hiatus were identified and marked with a suture using an arthroscopic suture passer. A dissection of the lateral side of the knee was then performed to identify the marked structure. Results: In all specimens, the dissection revealed that the fibers identified and marked arthroscopically had firm attachments to the popliteus tendon superiorly and inserted distally into the posterior aspect of the fibular head. The labeled structure was, therefore, the popliteofibular ligament. The popliteofibular ligament bifurcated distally with 2 insertion sites onto the fibular head. Conclusions: From this study, we concluded that the vertically oriented fibers descending from the inferior surface of the intra-articular portion of the popliteus tendon at the popliteal hiatus identified during arthroscopy are indeed those of the popliteofibular ligament. It is hoped that this knowledge will lead to improved outcomes in the treatment of injuries to the posterolateral corner of the knee.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 9 (November-December), 2001: pp 932–939     

Arthroscopic Reconstruction of the Posterior Cruciate Ligament Using Tibial-Inlay and Double-Bundle Technique

Biomechanical research has suggested that the double-bundle and tibial inlay technique is superior to the single-bundle and the transtibial tunnel method for posterior cruciate ligament (PCL) reconstruction. A combination the posterior tibial inlay and femoral double-bundle technique is thought to be an ideal method for PCL reconstruction. Recently, we successfully performed arthroscopic PCL reconstruction using the tibial-inlay and double-bundle technique. Achilles tendon–bone allograft is used and the bone plug for the arthroscopic tibial inlay fixation is designed in a cylindrical shape and perpendicular to the fiber texture of the Achilles tendon. Achilles tendon is manually split into deep and superficial layers to reconstruct anterolateral and posteromedial bundles as the natural insertion of PCL. The intra-articular lengths of each bundle between tibial tunnel and 2 femoral tunnels are measured to achieve fixation of the graft to the original PCL attachment. After tibial bone plug fixation with an absorbable interference screw and additional suture anchoring, the anterolateral bundle is fixed in a reduction position with the knee in 90° of flexion and the posteromedial bundle is fixed nearly in extension. This procedure makes it possible not only to reproduce the original concept of PCL tibial inlay graft arthroscopically without posterior arthrotomy, but also to achieve a more anatomic PCL reconstruction of the 2 bundles.     

The role of the popliteofibular ligament and the tendon of popliteus in providing stability in the human knee

Techniques for the selective cutting of ligaments in cadaver knees defined the static contributions of the posterolateral structures to external rotation, varus rotation and posterior tibial translation from 0 degrees to 120 degrees of flexion under defined loading conditions. Sectioning of the popliteofibular ligament (PFL) (group 1) produced no significant changes in the limits of the knee movement studied. Sectioning of the PFL and the popliteus tendon (femoral attachment, group 2) produced an increase of only 5 degrees to 6 degrees in external rotation from flexion of 30 degrees to 120 degrees (p < 0.001). Even when other ligaments were sectioned first (group 3), the maximum effect of the PFL was negligible. Our findings show that the popliteus muscle-tendon-ligament complex, lateral collateral ligament, and posterolateral capsular structures function as a unit. No individual structure alone is the primary restraint for the movements studied. Operative reconstruction should address all of the posterolateral structures, since restoration of only a portion may result in residual instability.     

Reconstructive treatment of posterolateral rotatory instability of the knee: a biomechanical study

Twelve cadaveric knees were tested to determine effective reconstructive treatment for severe chronic posterolateral rotatory knee instability accompanied by excessive varus and posterior laxity. Posterolateral, varus, and posterior laxity were measured, first with the ligaments intact, then after complete sectioning of the posterior cruciate ligament (PCL) and posterolateral structures, and finally after reconstruction of these structures in different orders. The increases in those laxities were produced following the sectioning of all of the structures and disappeared throughout the flexion range after combined reconstruction of the PCL, lateral collateral ligament (LCL), and popliteus tendon. However, some residual increase in the laxity was always observed if any of the three structures were excluded from reconstruction. Therefore, combined reconstruction of the PCL, LCL, and popliteus tendon is essential and adequate for treating severe chronic posterolateral rotatory instability.     

Posterolateral Corner Reconstruction of the Knee: Surgical Technique Utilizing a Bifid Achilles Tendon Allograft and a Double Femoral Tunnel

Reconstruction of the posterolateral corner of the knee has received increased attention in the recent literature. Basic science studies have helped us determine the 3 critical structures of the posterolateral corner: the lateral collateral ligament (LCL), the popliteus tendon, and the popliteofibular ligament. We have developed an anatomic posterolateral corner reconstruction that most closely resembles these 3 key structures and is based on the work of previous authors. Our technique is performed using a single Achilles allograft. The bone plug is secured in a femoral tunnel at the anatomic attachment of the popliteus tendon with an interference screw. The Achilles tendon is then split approximately 1 to 2 cm distal to the bone plug into 2 segments: (1) the popliteofibular ligament portion that is passed through a fibular tunnel starting at the anatomic attachment of popliteofibular ligament and fixed with a biointerference screw and (2) the static portion of the popliteus tendon securing this through a tibial tunnel passed from posterior to anterior right at the musculotendinous junction of the popliteus. The anterior limb of the Achilles tendon exiting the fibula is then brought back around, secured to the fibular attachment of the LCL with a suture anchor, and is then passed through a separate femoral tunnel placed at the anatomic attachment of the LCL.     

Posterior cruciate ligament and coupled posterolateral instability of the knee

We wanted to investigate the role of the posterior cruciate ligament (PCL) in the knee's posterolateral stability and the magnitude of the coupled posterolateral instability with the knee examined at 90 degrees of flexion. The coupled posterolateral instability of the knee was studied by selective ligament cutting in cadaver knees set at 90 degrees. The coupled posterolateral displacement after cutting the PCL was 173% of the intact knee. With an intact PCL, the coupled posterolateral displacement after cutting the popliteus tendon and lateral collateral ligament with the knee at 90 degrees of flexion was 299% of the intact knee. When the PCL was cut together with the popliteus tendon and lateral collateral ligament, the coupled posterolateral displacement was 367%. The PCL plays an important role in the posterolateral stability of the knee, and its injury may cause mild (< 5 mm) to moderate (5-10 mm) posterolateral instability. Thus, in a knee with posterolateral instability, injury of the PCL must be considered. With an intact PCL, the posterolateral instability was very recognizable with the knee at 90 degrees of flexion, and injury to the PCL further increased the posterolateral instability and caused posterior translation of the knee. Therefore, examination for posterolateral instability of the knee should also be performed with the knee at 90 degrees of flexion, which is much easier to perform in a clinical setting. A positive posterior translation rather than posterolateral instability at different knee positions differentiates knees with combined PCL and posterolateral instability from knees with isolated posterolateral instability.     

Ranawat Award paper. Effect of selective lateral ligament release on stability in knee arthroplasty

The current authors evaluated a fundamental approach to balancing the lateral ligaments of the knee that begins with aligning the implants correctly in flexion and extension, proceeds to assessing stability in flexion and extension, and concludes with releasing tight structures based on their function throughout the arc of flexion. Seventeen knees from cadavers were used to evaluate stability at various degrees of flexion after total knee arthroplasty, and then stability was reevaluated after release of selected ligaments. The iliotibial band and posterior capsule were effective lateral stabilizers only in full extension. The lateral collateral ligament had a major stabilizing effect throughout the arc from 0 degrees to 90 degrees flexion. The iliotibial band and popliteus tendon and posterolateral corner capsule had little effect when the other ligaments were intact. When tested in the absence of the other lateral ligaments, the popliteus tendon and posterolateral corner capsule had significant stabilizing effects throughout the flexion arc. The popliteus tendon exerted its effect mostly from 60 degrees to 90 degrees flexion. The posterolateral corner capsule was effective mostly at 0 degrees to 30 degrees flexion. The iliotibial band had a significant stabilizing effect from 0 degrees to 30 degrees flexion.     

Anatomy of the posterolateral aspect of the goat knee.

The purpose of this study was to determine the anatomy of the posterolateral aspect of the goat knee for future in vivo studies using a goat model to examine the natural history of posterolateral knee injuries. Twelve non-paired, fresh-frozen, adult goat knees were dissected to determine the anatomy of the posterolateral corner. The main posterolateral structures identified in the goat knee were the lateral collateral ligament, the popliteus muscle and tendon, popliteomeniscal fascicles, and the lateral gastrocnemius muscle. The lateral collateral ligament was extra-articular and coursed from its proximal attachment, located posterior and proximal to the lateral epicondyle, to its distal attachment on the lateral aspect of the fused proximal tibiofibula. The popliteus muscle attached to the medial edge of the posterodistal tibia, traveled anterolaterally, became intra-articular at its musculotendinous junction, and attached to the lateral femur just distal to the lateral epicondyle. Distinct popliteomeniscal fascicles attached the lateral meniscus to the popliteus muscle and tendon, and a fascial attachment from the musculotendinous junction of the popliteus muscle coursed to the lateral tibial plateau. This study provided information on the structures present in the posterolateral aspect of the goat knee and enhanced our understanding of their relationships to analogous structures in the human knee. This information is important to enable future development of potential models of the natural history of posterolateral knee injuries and also to test surgical techniques and the in vivo effects of these injuries on cruciate ligament reconstructions.     

Anatomic Posterolateral Corner Knee Reconstruction

Injuries to the lateral collateral ligament and posterolateral corner of the knee, particularly when combined with anterior cruciate or posterior cruciate ligament injuries, can result in profound symptomatic knee instability. Although many surgical improvements have been made in reconstruction of anterior and posterior cruciate ligament injuries, reconstruction of the posterolateral corner has had less predictable results, with residual pathologic laxity especially in the chronic situation. This has stimulated many surgeons to recommend acute repair of posterolateral knee injuries. This article describes a more anatomic reconstruction of the posterolateral corner for chronic instability, recreating the lateral collateral ligament and popliteofibular ligament using either autogenous or allograft soft tissue and an interference screw technique. In a small clinical series, this has proven to restore varus rotation and external rotation patholaxities with a high degree of predictability.     

Anatomic double-bundle posterior cruciate ligament reconstruction using hamstring tendons

Recent biomechanical studies have shown that an anatomic double-bundle posterior cruciate ligament (PCL) reconstruction is superior in restoring normal knee laxity compared with the conventional single-bundle isometric reconstruction. We describe a modification of an endoscopic PCL reconstruction technique using a double-bundle Y-shaped hamstring tendon graft. A double- or triple-bundle semitendinosus-gracilis tendon graft is used and directly fixed with soft threaded biodegradable interference screws. In the medial femoral condyle, 2 femoral tunnels are created inside-out through a low anterolateral arthroscopic portal. First, in 80° of flexion, the double-stranded gracilis graft is fixed with an interference screw inside the lower femoral socket, representing the insertion site of the posteromedial bundle. In full extension the combined semitendinosus-gracilis graft is pretensioned and fixed inside the posterior aspect of the single tibial tunnel. The double- or triple-stranded semitendinosus tendon is inserted in the higher femoral tunnel, presenting the insertion site of the anterolateral bundle. Finally, pretension is applied to the semitendinosus bundle in 70° of flexion and a third screw is inserted. Using this technique, the stronger semitendinosus part of the double-bundle graft, which mimics the anterolateral bundle of the PCL, is fixed in flexion, whereas the smaller gracilis tendon part (posteromedial bundle) is fixed in full extension. Thus, a fully arthroscopic anatomic PCL reconstruction technique is available that may better restore normal knee kinematics as compared to the single-stranded isometric reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 1 (January), 2001: pp 88–97     

股骨单隧道内分叉双束纤维重建后交叉韧带的实验研究

目的在人膝关节标本上行股骨单隧道分叉双束纤维重建后交叉韧带(posterior cruciate ligament,PCL),探讨其术式的优缺点。方法应用力学试验机对14侧捐赠新鲜冷冻人膝关节标本进行生物力学测试,男12侧,女2侧;年龄20～31岁。标本股骨段长20cm,胫骨段长20cm。首先测量PCL完整时胫骨后移距离和交叉韧带的应变(完整组,n=14);然后切断PCL(切断组,n=14),测量胫骨受力时的后移距离后,再将标本随机分为两组:单束重建组(n=7)和分叉双束重建组(n=7),分别测量屈膝0、30、60、90和120°5个角度时胫骨后移距离和移植韧带的应变。结果胫骨受到100N后向力量,完整组在不同屈膝角度下,胫骨向后移位1.97±0.29～2.60±0.23mm,前外束和后内束纤维交替紧张松弛。切断组膝关节明显松弛,胫骨向后移位达11.27±1.06～14.94±0.67mm,与完整组比较差异有统计学意义(P<0.05);单束纤维重建组,在不同屈膝角度下胫骨向后移位1.99±0.19～2.72±0.38mm,移植韧带持续紧张。双束纤维重建组在不同屈膝角度下胫骨向后移位2.27±0.32～3.05±0.44mm,移植的双束纤维交替紧张,协同作用。组内比较:双束重建组在不同屈膝角度时胫骨向后位移差异无统计学意义(P>0.05),而单束重建组在屈膝90°时与屈膝30、60和120°时相比,胫骨后移增大,差异有统计学意义(P<0.05)。结论股骨单隧道内分叉双束纤维重建PCL术在各屈膝角度均能有效防止胫骨后移,股骨单隧道单束重建术屈膝90°时后移较其他角度时增大。分叉双束重建PCL的两束纤维束交替紧张,生物力学特征更接近于正常PCL。     

Double-bundle posterior cruciate ligament reconstruction with quadriceps and semitendinosus tendon grafts

This study presents a novel arthroscopic technique for double-bundle reconstruction of the posterior cruciate ligament. A quadriceps tendon-patellar bone autograft is used to reconstruct the major anterolateral bundle. An additional double-stranded semitendinosus tendon is used to reconstruct the posteromedial bundle. In 70° of flexion and full extension with anterior drawer force, the quadriceps tendon graft and semitendinosus tendon graft are fixed inside the anterior aspect of the single tibial tunnel, respectively. An anatomic reconstruction can be achieved by using these 2 autografts.