Management and complications of anterior cruciate ligament injuries in skeletally immature patients: survey of the Herodicus Society and The ACL Study Group

Expert opinion regarding experience with the management and complications of pediatric anterior cruciate ligament (ACL) injuries was studied by surveying members of The Herodicus Society and The ACL Study Group. There was large practice variation in initial management and ACL reconstruction technique. There were 15 reported cases of growth disturbance: 8 cases of distal femoral valgus deformity with arrest of the lateral distal femoral physis, 3 cases of tibial recurvatum with arrest of the tibial tubercle apophysis, 2 cases of genu valgum without arrest, and 2 cases of leg length discrepancy. Associated factors included fixation hardware across the lateral distal femoral physis in 3 cases, bone plugs of a patellar tendon graft across the distal femoral physis in 3 cases, large (12 mm) tunnels in 2 cases, fixation hardware across the tibial tubercle apophysis in 3 cases, lateral extra-articular tenodesis in 2 cases, and over-the-top femoral position in 1 case. Based on this experience, we recommend a guarded approach to ACL reconstruction in the skeletally immature patient with careful attention to technique and follow-up.     

Effect of tibial tunnel dilation on pullout strength of semitendinosus-gracilis graft in anterior cruciate ligament reconstruction

This biomechanical cadaver study evaluated the effect of tibial tunnel dilation on the pullout strength of semitendinosus and gracilis tendon grafts in anterior cruciate ligament reconstruction. Fourteen grafts were harvested, and the anterior cruciate ligament was reconstructed in the tibial and femoral tunnels. All femoral tunnels were reamed to the diameter of the graft. In seven knees, the tibial tunnels were reamed to the diameter of the graft. In the remaining seven knees, the tibial tunnels were reamed 2 mm smaller than the diameter of the graft and then serially dilated to the graft size using cannulated smooth dilators. Mechanical testing to graft failure was conducted. All grafts failed by graft pullout from the tibial tunnel. However, mean peak load was significantly higher for the dilated tibial specimens (616 +/- 263 N) than for the reamed specimens (453 +/- 197 N) (P = .0025).     

The effect of placing a tensioned graft across open growth plates. A gross and histologic analysis

BACKGROUND: Midsubstance tears of the anterior cruciate ligament in skeletally immature patients are increasingly common and are a challenging problem. The results of nonoperative treatment are no better in children than they are in adults. Physeal-sparing reconstructive procedures have yielded poor results. Reconstructive procedures that are utilized in adults violate the physis, potentially resulting in growth abnormalities. The objective of this study was to provide a model for reconstruction of the anterior cruciate ligament in skeletally immature patients by evaluating the effects of a tensioned connective-tissue graft placed across the canine physis. METHODS: Twelve ten-week-old beagles underwent reconstruction of the anterior cruciate ligament consisting of placement of fascia lata autograft through drill-holes across the femoral and tibial physes, tensioning of the graft to 80 N, and fixing it with screws and washers. The contralateral limb served as a control. One dog was eliminated from the study secondary to a postoperative infection. Four months postoperatively, the dogs were killed and were inspected grossly, radiographically, and histologically for any evidence of growth disturbance. RESULTS: Significant valgus deformity of the distal part of the femur (p < 0.001) and significant varus deformity of the proximal part of the tibia (p = 0.03) developed in the treated limbs. Neither radiographic nor histologic examination demonstrated any evidence of physeal bar formation. CONCLUSIONS: Significant growth disturbances occur with excessively tensioned transphyseal reconstruction of the anterior cruciate ligament in the canine model. These growth disturbances occur without radiographic or histologic evidence of physeal bar formation.     

Anatomic Double Bundle: A New Concept in Anterior Cruciate Ligament Reconstruction Using the Quadriceps Tendon

Surgical procedures for double-bundle anterior cruciate ligament reconstruction, which currently use hamstring graft, have been described, but some concerns remain regarding graft fixation and the ability to obtain adequate bundle size. We report an original double-bundle anterior cruciate ligament reconstruction technique using a quadriceps tendon graft and a simplified outside-in femoral tunnel–drilling process. The graft consists of a patellar bone block with its attached tendon split into superior and inferior portions, which yields 2 bundles. The anteromedial tunnel is drilled from the outside through a small lateral incision by use of a guide. The posterolateral tunnel is made through the same incision with a specific guide engaged in the anteromedial tunnel. A single tibial tunnel is created. The graft is routed from the tibia to the femur with the bone block in the tibial tunnel and the 2 bundles in their respective femoral tunnels. After fixation of the bone block in the tibia, the 2 bundles are tensioned and secured separately in their femoral tunnels.     

Editorial Commentary: The All-Epiphyseal Anterior Cruciate Ligament Distal Femoral Approach: Sockets or Tunnels?

I believe that the distal femoral approach for anterior cruciate ligament reconstruction in the skeletally immature athlete with 3 to 6 years of remaining growth is best performed with an all-inside, all-epiphyseal technique using sockets rather than an outside-in approach creating tunnels. A shorter socket rather than a longer tunnel exposes a smaller surface area of the lateral distal femoral physis to potential compromise and resultant valgus malalignment. In addition, exiting the lateral femoral aspect of the epiphysis with a full-diameter tunnel as compared with a smaller diameter drill hole used to prepare a socket places the posterior articular cartilage, the lateral collateral ligament and anterolateral ligament footprints, and the popliteus tendon insertion at risk. My preference for sockets is also related to my belief that they provide a superior biologic milieu for graft incorporation compared with a full-length tunnel with the attendant violation of the lateral femoral cortex of the epiphysis.     

Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study

BACKGROUND: High tension in an anterior cruciate ligament graft adversely affects both the graft and the knee; however, it is unknown why high graft tension in flexion occurs in association with a posterior femoral tunnel. The purpose of the present study was to determine the effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on the tension of an anterior cruciate ligament graft during passive flexion. METHODS: Eight cadaveric knees were tested. The angle of the tibial tunnel was varied to 60 degrees, 70 degrees, and 80 degrees in the coronal plane with use of three interchangeable, low-friction bushings. The femoral tunnel, with a 1-mm-thick posterior wall, was drilled through the tibial tunnel bushing with use of the transtibial technique. After the graft had been tested in all three tibial bushings with one femoral tunnel, the femoral tunnel was filled with bone cement and the tunnel combinations were tested. Lastly, the graft was replaced in the 80 degrees femoral and tibial tunnels, and the tests were repeated with excision of the lateral edge of the posterior cruciate ligament in 2-mm increments. Graft tension, the flexion angle, and anteroposterior laxity were recorded in a six-degrees-of-freedom load-application system that passively moved the knee from 0 degrees to 120 degrees of flexion. RESULTS: The graft tension at 120 degrees of flexion was affected by the angle of the femoral tunnel and by incremental excision of the posterior cruciate ligament. The highest graft tension at 120 degrees of flexion was 169 +/- 9 N, which was detected with the graft in the 80 degrees femoral and 80 degrees tibial tunnels. The lowest graft tension at 120 degrees of flexion was 76 +/- 8 N, which was detected with the graft in the 60 degrees femoral and 60 degrees tibial tunnels. The graft tension of 76 N at 120 degrees of flexion with the graft in the 60 degrees femoral and 60 degrees tibial tunnels was closer to the tension in the intact anterior cruciate ligament. Excision of the lateral edge of the posterior cruciate ligament in 2 and 4-mm increments significantly lowered the graft tension at 120 degrees of flexion without changing the anteroposterior position of the tibia. CONCLUSIONS: Placing the femoral tunnel at 60 degrees in the coronal plane lowers graft tension in flexion. Our results suggest that high graft tension in flexion is caused by impingement of the graft against the posterior cruciate ligament, which results from placing the femoral tunnel medially at the apex of the notch in the coronal plane.     

Free physeal transplantation in the rabbit. An experimental approach to focal lesions

We have developed a procedure to transplant free autogenous iliac-crest physeal grafts into defects created in the lateral aspect of the distal femoral physis of rabbits. Excision of a portion of the lateral part of the physis led consistently to formation of a bone bridge, growth arrest, and valgus deformity. There was no evidence of increased activity by the persisting physis to fill the defect or of differentiation of mesenchymal cells into a functioning physeal layer. We carried out preliminary studies to define the optimum conditions for obtaining and transplanting a free autogenous iliac-crest physeal graft into the femoral physeal defect. The iliac apophysis is composed of a fibrocartilaginous layer, cartilage similar to epiphyseal cartilage, and a physis. The graft included the physis and some overlying epiphyseal cartilage but the outermost fibrocartilaginous layer and the surrounding perichondrium were removed, as these two tissues were believed to inhibit diffusion. The graft was separated gently from the metaphysis. Histological studies showed that the separation occurred at the lower hypertrophic-chondrocyte zone. After optimum techniques had been developed for transplantation and the feasibility of the procedure had been established in twenty-one rabbits, the capacity of the physeal transplants to prevent bone-bridge formation, growth arrest, and valgus deformity was evaluated in thirty-nine rabbits, three to four months old, using the standardized transplantation procedure. The results were assessed in terms of the gross and radiographic appearance of the femur, measurements of length, and histological characteristics. The transplanted physis retained its normal morphology, united with the residual part of the original femoral physis, and participated in endochondral bone formation. Bone-bridge formation between the femoral epiphysis and metaphysis, growth arrest, and valgus deformity were prevented or minimized in most animals, and the physeal transplants yielded good or excellent results in 60 per cent of the procedures using stringent criteria. The results of this study show that free physeal transplants into focal defects can remain viable and function satisfactorily if they are fashioned properly and inserted gently. CLINICAL RELEVANCE: This study demonstrated that transplantation of an iliac-crest physis into a defect of the lateral aspect of the distal femoral physis can prevent bone-bridge formation, growth arrest, and the development of valgus deformity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Arthroscopic Posterior Cruciate Ligament Reconstruction in a Skeletally Immature Patient: A New Technique With Case Report

Pediatric intrasubstance posterior cruciate ligament (PCL) injuries are rare but present a significant treatment challenge. Untreated instability may lead to further knee injury, including meniscal or chondral damage. Surgical intervention risks damage to the physis, growth arrest, and angular deformity. We present the case of a skeletally immature 11-year-old boy with a high-grade intrasubstance PCL injury reconstructed using an all-arthroscopic tibial inlay technique modified to minimize risk of physeal injury. The femoral tunnels were placed entirely within the epiphysis, and the tibial physis was minimally crossed with a small drill hole and suture material. At 17 months' follow up, the patient had returned to full activity, including sports. He had a grade 1 posterior drawer and no posterior sag. Radiographs showed no degenerative changes. Both the proximal tibial and distal femoral physes were widely patent with no angular deformity. The patient had a 1-cm leg length discrepancy, with the operative limb being longer. This technical note with a case report describes a novel physeal-sparing reconstruction of the PCL in a pediatric patient with open physes.     

In vitro comparison of elongation of the anterior cruciate ligament and single- and dual-tunnel anterior cruciate ligament reconstructions.

This study evaluated strain in the normal anterior cruciate ligament (ACL) and compared it to four different double-strand hamstring tendon reconstructive techniques. Seventeen fresh-frozen knees from 11 cadavers were tested. The strain in the anteromedial and posterolateral bands of the native ACL and their equivalents in four autograft techniques were measured using differential variable reluctance transducers. The anteromedial band of the intact ACL shortened from 0 degree -30 degrees of flexion, then lengthened to 120 degrees; the posterolateral band of the intact ACL shortened from 0 degree - 120 degrees of flexion. Following ACL excision, these knees underwent reconstruction with double-strand hamstring tendons with either single tibial and femoral tunnels, single tibial and dual femoral tunnels, dual tibial and single femoral tunnels, or dual tibial and dual femoral tunnels. With the exception of the dual-band, dual-tunnel technique, all of the procedures placed greater strain on the reconstructive tissues than was observed on the native ACL, after approximately 30 degrees of flexion. These results indicate that dual-band hamstring tendon reconstructions placed with single tibial and femoral tunnels do not address the complexity of the entire ACL. Rather, these procedures appear to only duplicate the effect of the anteromedial band, while perhaps overconstraining the joint as a result of its inability to reproduce the function of the posterolateral band. During rehabilitation following ACL reconstruction, therefore, only from 0 degree - 30 degrees of the graft tissues are not significantly strained. Dual tibial and femoral tunnel techniques should be evaluated further to more closely recreate knee kinematics following ACL reconstruction.     

Reconstructive interventions of the posterior cruciate ligament--experimental studies of isometric aspects. Part II: Studies of the posterior cruciate ligament replacement model]

Isometric positioning of the posterior cruciate ligament (PCL) graft is important for successful reconstruction of the PCL-deficient knee. This study documents the relationship between graft placement and changes in intra-articular graft length during passive range of motion of the knee. In eight cadaveric knees the PCL was identified and cut. The specimens were mounted in a stabilizing rig. PCL reconstruction was performed using a 9-mm-thick synthetic cord that was passed through tunnels 10 mm in diameter. Three different femoral graft placement sites were evaluated: (1) in four specimens the tunnel was located around the femoral isometric point, (2) in two specimens the tunnel was positioned over the guide wire 5 mm anterior to the femoral isometric point, (3) in two specimens the tunnel was positioned over the guide wire 5 mm posterior to the isometric femoral point. In all knees only one tibial tunnel was created around the isometric tibial point. The location of the isometric points was described in part I of the study. The proximal end of the cord was fixed to the lateral aspect of the femur. Distally the cord was attached to a measuring unit. The knees were flexed from 0 degree to 110 degrees, and the changes in the graft distance between the femoral attachment sites were measured in 10 degrees steps. Over the entire range of motion measured the femoral tunnels positioned around the isometric point produced femorotibial distance changes of within 2 mm. The anteriorly placed tunnels produced considerable increases in femorotibial distance with knee flexion, e.g. about 8 mm at 110 degrees of flexion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anterior cruciate ligament injuries in the skeletally immature patient

Injuries of the anterior cruciate ligament (ACL) in children are more frequent than once thought. Special factors must be taken into consideration when treating ACL injuries in the skeletally immature patient. Risks of surgery must be weighed against potential damage to the knee caused by repeated injury. The authors prefer the use of both tibial and femoral centrally placed drill holes, hamstring tendon autografts, fixation distant from the physis, and avoidance of dissection near the physis. This technique will minimize damage to the physis and should not hinder normal growth.     

Physeal arrest about the knee associated with non-physeal fractures in the lower extremity

The cases of seven patients who had a physeal arrest about the knee in association with nonphyseal fractures in the lower extremity were reviewed. The patients were between ten and twelve and one-half years old at the time of injury, and the physeal arrest involved either the posterolateral part of the distal femoral physis or the anterior part of the proximal tibial physis. There was no evidence of iatrogenic trauma to the physis. Recognition of the physeal injury was delayed for an average of one year and ten months until a gross angular deformity appeared. Adolescents who have fractures of the lower extremities that do not appear to involve a physeal plate should nevertheless be evaluated and followed for possible physeal injury about the knee that can be detected only after additional growth has taken place.     

Radiological landmarks for placement of the tunnels in single-bundle reconstruction of the anterior cruciate ligament

There is little evidence examining the relationship between anatomical landmarks, radiological placement of the tunnels and long-term clinical outcomes following anterior cruciate ligament (ACL) reconstruction. The aim of this study was to investigate the reproducibility of intra-operative landmarks for placement of the tunnels in single-bundle reconstruction of the ACL using four-strand hamstring tendon autografts. Isolated reconstruction of the ACL was performed in 200 patients, who were followed prospectively for seven years with use of the International Knee Documentation Committee forms and radiographs. Taking 0% as the anterior and 100% as the posterior extent, the femoral tunnel was a mean of 86% (sd 5) along Blumensaat's line and the tibial tunnel was 48% (sd 5) along the tibial plateau. Taking 0% as the medial and 100% as the lateral extent, the tibial tunnel was 46% (sd 3) across the tibial plateau and the mean inclination of the graft in the coronal plane was 19 degrees (sd 5.5). The use of intra-operative landmarks resulted in reproducible placement of the tunnels and an excellent clinical outcome seven years after operation. Vertical inclination was associated with increased rotational instability and degenerative radiological changes, while rupture of the graft was associated with posterior placement of the tibial tunnel. If the osseous tunnels are correctly placed, single-bundle reconstruction of the ACL adequately controls both anteroposterior and rotational instability.     

Arthroscopic Posterior Cruciate Ligament Augmentation Using an Autogenous Hamstring Tendon Graft and the Posterior-Posterior Triangulation Technique

We describe a modification of the currently practiced arthroscopic posterior cruciate ligament (PCL) reconstruction techniques. We augmented the injured PCL with quadrupled autogenous hamstring tendon grafts using the arthroscopic posterior-posterior triangulation method and a single-incision transtibial approach. The tibial drill guide was introduced through the anteromedial portal and positioned onto the fossa for the PCL on the tibia under arthroscopic guidance from the posterolateral portal. The femoral tunnel was made 10 mm posterior to the articular cartilage of the medial femoral condyle by use of the anterior cruciate ligament Beath pin (Arthrex, Naples, FL) introduced through the far-inferior anterolateral portal. The tendon graft was positioned in the knee joint by use of the tibial and femoral double-folded silk loops that traversed the bony tunnels. The graft was fixed by use of bioabsorbable Intrafix screw systems (DePuy Mitek, Raynham, MA) at both the ends. The arthroscopic posterior-posterior triangulation method provides adequate exposure of the posterior knee compartment; this allows for convenient instrumentation and safe and accurate placement of the bony tunnels with preservation of the PCL remnants. We believe that retention of the remnant PCL fibers is biologic and contributes to earlier healing and strengthening of the tendon graft.     

Ideal tibial tunnel length for endoscopic anterior cruciate ligament reconstruction

A successful single-incision endoscopic anterior cruciate ligament reconstruction using bone-patellar tendon-bone autograft requires attention to many technical details. The emphasis of placing the femoral bone plug flush with the opening of the femoral tunnel results in distal shift of the graft. Longer tibial tunnels are required to prevent excessive graft extrusion. The purpose of this study is to compare four direct and indirect measurement methods of tibial tunnel preparation to determine which method can be used to create consistently reproducible tibial tunnels that prevent excessive extrusion or recession of the graft within the tunnel. Tunnels placed at the empiric angles of 40 degrees, 50 degrees, and 60 degrees to the tibial plateau resulted in the incidence of acceptable tibial tunnel lengths of 44%, 83%, and 39%, respectively. Tunnels placed at an angle determined by the formula "N + 7" where 7 degrees is added to the patellar tendon length (N) resulted in acceptable tunnels 89% of the time. Direct measurement methods using the formulas "graft - 50 mm" and "N + 2 mm" resulted in acceptable tibial tunnels of 44% and 100%, respectively. We recommend using the "N + 7" in conjunction with the "N + 2 mm" formula to obtain the advantages of both indirect and direct measurement methods.Arthroscopy 1998 Jan-Feb;14(1):9-14     

Tibial deformities and failures of anterior cruciate ligament reconstruction in immature rabbits

We evaluated the effects of anterior cruciate ligament (ACL) reconstruction on growth and development of the knee in immature New Zealand white rabbits (8 weeks old). In 25 rabbits, the ACL was reconstructed with an autogenous iliotibial band (ITB), and in 31 rabbits an autogenous patellar tendon bone (PTB) graft was used. Reconstructed ACLs failed in 20 of the 25 animals in the ITB group and in 26 of 31 in the PTB group. Gross and histological examinations in the animals with successfully reconstructed ACLs (5 in the ITB group and 5 in the PTB group) showed significant tibial deformity and tibial shortening, with progressive thinning of the epiphyseal plate and disorders of the cartilage column on the medial side of the tibia. These abnormalities were not observed in rabbits whose ACLs were torn. This experiment showed that successful ACL reconstruction in young animals with an open physis may result in deformities and/or shortening of the leg. Accordingly, we believe that special care should be taken when surgically reconstructing an ACL in a young patient whose physes are still open. Received for publication on Oct. 29, 1997; accepted on Jan. 13, 1998     

Effect of interposition material on mechanical behavior in partial physeal resection: a canine model

A canine model was used to investigate the mechanical properties of the partially resected physis and the role of load-sharing interposition material. Ten puppy knees were loaded axially, with strain gauges placed across the proximal tibial physis. After partial physeal resections, the knees were retested with and without polymethylmethacrylate (PMMA) in the resection gap. PMMA interposition moderated the change in physeal displacement noted with increasing areas of resection. The Heuter-Volkman law predicts decreased growth in response to increased physeal stress. We therefore recommend use of a load-sharing interposition material in resection of large physeal arrests in weightbearing areas.     

Bone tunnel enlargement after anterior cruciate ligament reconstruction with semitendinosus tendon using Endobutton fixation on the femoral side

We evaluated 29 knees with a minimum follow-up of 2 years after anterior cruciate ligament (ACL) reconstruction using doubled autogenous semitendinosus tendons. On the femoral side, a 5-mm Mersilene tape (Ethicon, Norderstedt, Germany) with an Endobutton (Acufex Microsurgical, Mansfield, MA) was used. The tendon was fixed on the tibial side with two staples. Regarding the IKDC score, 66% of the patients were graded as normal or nearly normal. The anterior laxity side-to-side difference (KT 1000, man-max-drawer) was under 3 mm in 55% and under 5 mm in 90%. Radiographs taken in the lateral and anteroposterior projections of the knee showed sclerotic bone tunnel margins. The diameter of the bone tunnels were measured, corrected for magnification, then compared with the original reamed diameter to determine any change in size. Enlargement of at least 2 mm was identified in 72% of the femoral tunnels and 38% of the tibial tunnels. No correlation was found concerning the enlargement of the tunnel and the IKDC score or the residual joint laxity. We conclude that using an Endobutton-Mersilene construct in ACL reconstruction leads to femoral and tibial bone tunnel enlargement at follow-up of 2 years. (Arthroscopy 1998 Nov-Dec;14(8):810-5.)     

Editorial Commentary: Anterior Cruciate Ligament Graft Tunnel Mismatch: The Long and Short of It

Anterior cruciate ligament graft size is an important consideration when planning the length of the tibial tunnel. In general, longer grafts require longer tunnels to accommodate the graft. Ideally, the tibial bone plug should be flush with the tibial cortex after graft passage and femoral fixation. Alternatively, allograft bone-patellar tendon-bone grafts can be selected based on their lengths to assure an ideal fit in the tibial tunnel. However, there are increased risks of allograft failure in young patients that anterior cruciate ligament surgeons should recognize.