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© 1999 The Journal of Bone and Joint Surgery, Inc. Valgus Deformity After Reconstruction of the Anterior Cruciate Ligament in a Skeletally Immature Patient. A Case Report*  , ERIE, PENNSYLVANIAInvestigation performed at Shriners Hospital for Children, Erie
Whether acute or chronic, rupture of the anterior cruciate ligament is uncommon in children, most likely because the strength of the ligament is greater than that of bone or physes in children3,5. However, intrasubstance ruptures of the anterior cruciate ligament can occur in young patients1,2,4,6-8,11-17,19. A heightened awareness of injuries to the ligament and the fear of irreparable damage to the cartilage and menisci have created a trend toward operative treatment1,2,4,6-8,11-17,19. Intra-articular reconstruction of the anterior cruciate ligament has been successful in adults; however, drilling across an open growth plate is a cause of concern because it may lead to the formation of an osseous bridge, resulting in premature physeal closure, limb-length discrepancy, and angulation of the involved extremity10. We report on a fourteen-year-old boy who was managed with a transphyseal intra-articular reconstruction of the anterior cruciate ligament of the right knee. He subsequently had premature closure of the distal femoral physis that resulted in a valgus deformity of the lower extremity.
A boy, fourteen years and four months old, sustained an injury of the right knee while playing football. The knee gave way and immediately swelled. The patient was evaluated in an emergency room, and he was referred to an orthopaedic surgeon. Physical examination revealed a large effusion in the right knee, positive Lachman and drawer signs, and a positive pivot-shift test. Knee flexion was limited to 90 degrees. Radiographic examination of the knee revealed no fractures. A rupture of the anterior cruciate ligament was diagnosed at that time. The patient began a rehabilitation program in an attempt to regain a full range of motion of the knee. After one month of rehabilitation, the patient regained a full range of motion but the right knee remained unstable. The physician recommended reconstruction of the anterior cruciate ligament. The hospital chart contained no information regarding the amount of growth remaining, the stage according to the classification system of Tanner20, the heights of family members, the bone age, or the occurrence of an adolescent growth spurt. An arthroscopically assisted reconstruction of the anterior cruciate ligament with a double-stranded semitendinosus graft was performed. The original anterior cruciate ligament was completely ruptured. There was no evidence of a tear of the medial or lateral meniscus or of areas of cartilage degeneration in the three compartments of the knee. The stump of the ligament was debrided, and a notchplasty was performed. A 45-degree tibial tunnel of unknown diameter and a nine-millimeter endoscopic femoral tunnel were drilled. An Arthrex guide (Naples, Florida) was used to insert the looped double-stranded tendon graft across the tibial and femoral tunnels. The tendon was transfixed with a cannulated screw across the lateral femoral condyle. Cancellous bone plugs were inserted within the tibial and femoral tunnels. The distal part of the tendon was transfixed with two six-millimeter staples at the distal end of the tibial tunnel (Fig. 1). After the reconstruction was completed, intraoperative examination of the knee revealed negative Lachman and pivot-shift tests with a firm end point.
Two years later, when the patient was sixteen years and three months old, he was first seen at our institution because of a progressive valgus deformity of the involved lower extremity. There was no history of trauma, pain, or instability after the procedure. Physical examination revealed a full range of motion of the knee and a negative pivot-shift test. Lachman and drawer tests demonstrated grade-I laxity with a stable end point. The knee was stable to varus and valgus stress. The Q-angle measured 20 and 5 degrees for the right and left knees, respectively. Radiographs showed the anatomical axis to be 67 degrees for the right knee and 81 degrees for the left knee. The mechanical axis was 74 degrees for the right knee and 88 degrees for the left knee. The cannulated transfixing screw crossed the lateral aspect of the distal femoral physis. The tibial staples remained outside the proximal tibial physis. Bone age was determined with the technique described in the atlas by Greulich and Pyle9 and was consistent with that of a boy who was fifteen years and two months old. The distal femoral growth plate appeared to be completely fused on radiographs (Fig. 2). An opening-wedge osteotomy with interposition of a tricortical bone allograft was performed on the distal part of the right femur. A distal femoral epiphyseodesis was done concurrently in the left limb to prevent any remaining growth that otherwise might have caused a limb-length discrepancy. A blade-plate was used for fixation after correction of the valgus angulation of the femur by 14 degrees (Fig. 3). A distal femoral epiphyseodesis was not performed in the right limb because the growth plate appeared to be fused on radiographs and it was thought that any growth remaining would be prevented by the blade-plate device.
Postoperative radiographic examination revealed equal tibiofemoral angles of 9 degrees. At the most recent follow-up visit, when the patient was seventeen years and three months old, he had a full range of motion of the knee and equal Q-angles on clinical examination. Radiographs revealed complete healing of the site of the distal femoral osteotomy and fully fused growth plates in the knee, and the tibiofemoral angles remained unchanged at 9 degrees.
Disruption of the anterior cruciate ligament in skeletally immature patients is being diagnosed with increasing frequency. A better understanding of this injury in children and adolescents and a higher level of clinical suspicion account for much of this increase in frequency14,19. However, the true prevalence and natural history of ruptures of the anterior cruciate ligament in skeletally immature patients remain unknown. Much of the available information about the natural history has been extrapolated from studies performed on adults who had an injury of the ligament. Recent data indicate that children and adolescents who have a ruptured anterior cruciate ligament are predisposed to the same sequelae—that is, instability, reinjury, and possible degenerative changes—as adults2. Because of the presumed poor prognosis after a rupture of the anterior cruciate ligament, several treatment options, including bracing and rehabilitative therapy, have been examined. McCarroll et al. reported on sixteen patients who had been managed with bracing followed by a program of rehabilitation; nine of the patients discontinued participation in their sport because of recurrent instability15. Graf et al. studied twelve patients, eight of whom had been managed nonoperatively; seven of the eight had additional injuries of the knee and eventually needed reconstructive procedures8. Kannus and Järvinen evaluated thirty-two patients eight years after nonoperative management; the seven patients who had had a severe (grade-III) ligamentous injury had a poor result11. On the whole, short-term and intermediate-term studies have demonstrated a poor return to the preinjury level of activity and repeated episodes of instability16. Operative intervention in skeletally immature knees has been controversial because of the possibility of partial physeal disruption with resulting limb-length discrepancy and angular deformity due to crossing of the physis with a graft. As obvious as this danger seems and as hazardous as disrupting an open growth plate is, many investigators have reported either partial or total transphyseal intra-articular reconstructions of the anterior cruciate ligament without a severe growth disturbance1,12,13,15. Guzzanti et al.10 and Stadelmaier et al.18 studied animal models with transphyseal intra-articular reconstructions of the anterior cruciate ligament in rabbits and dogs, respectively. In investigations of small numbers of animals, they saw no formation of a physeal bar in the tunnels crossed by the reconstructed tendon. Guzzanti et al., however, reported two cases of tibia valga without an epiphyseodesis. The exact amount of physeal disruption in humans before a growth disturbance occurs remains unknown. Few growth disturbances have been reported in children who were managed with transphyseal intra-articular reconstruction. Some studies were flawed by a limited number of patients, a short duration of follow-up, and a limited assessment of future growth1,12,13,15. Lipscomb and Anderson reviewed the results for twenty-four patients who had been managed with reconstruction with the insertion of semitendinosus and gracilis tendon grafts into drill-holes in the tibial and femoral epiphyses12. Five patients had a limb-length discrepancy of six to ten millimeters; one, a thirteen-millimeter discrepancy; and one, a twenty-millimeter discrepancy. The twenty-millimeter discrepancy was attributed to stapling across the tibial and femoral physes. Neither current nor future growth of the patients was assessed preoperatively. The growth disturbances were rationalized as being acceptable discrepancies among the normal population. Andrews et al. used a seven-millimeter allograft, centrally placed across the tibial physis and in an over-the-top femoral position, in eight patients1. Assessment of growth and maturation preoperatively and postoperatively consisted of staging according to the system of Tanner20, evaluation of secondary sex characteristics, examination of a radiograph of the hand and wrist to determine bone age, determination of family growth characteristics, and growth prediction based on bone age. Two patients had a growth disturbance: the involved limb of one patient was ten millimeters longer than the uninvolved limb, and the involved limb of the other patient was twelve millimeters shorter than the uninvolved limb. Both disturbances occurred on the femoral side, which the authors could not explain, given the technique that had been used. McCarroll et al. reported on their algorithm for the management of sixty junior-high-school children who had a midsubstance rupture of the anterior cruciate ligament15. The stage according to the system of Tanner20, family history of growth, bone-age determinants, and occurrence of an adolescent growth spurt were evaluated preoperatively. The patients who were in stage I or II according to the system of Tanner, had physes that were wide open without evidence of an adolescent growth spurt, or had a noticeable height discrepancy when compared with grown siblings and parents were managed nonoperatively. The patients who were more mature were managed with a transphyseal reconstruction involving insertion of a ten-millimeter-wide bone-patellar ligament-bone autogenous bone graft inserted into the tibial and femoral tunnels. No postoperative growth disturbances or angular deformities were noted. The mean duration of follow-up was only two years, after which time fifty-five of the sixty children were able to return to their original sport. Lo et al. reported on five patients who had been managed with reconstruction of the anterior cruciate ligament when they were very young13,14. A tunnel was drilled across an open tibial physis, and the graft was placed in an over-the-top position on the femur. The tibial tunnels were six millimeters or less in diameter. At a mean of 7.4 years, there was no noticeable limb-length discrepancy or angular deformity and all of the knees were clinically stable. Four of the five patients returned to their preinjury level of activity. A careful assessment of a skeletally immature patient who has a ruptured anterior cruciate ligament is critical before any operative procedure is considered. The patient who is the subject of the present study had an insufficient preoperative assessment of skeletal growth. The treating surgeon believed that the patient "was nearing the termination of longitudinal growth clinically and radiographically"; thus, the surgeon "felt comfortable with intra-articular reconstruction." Yet it is evident on postoperative radiographs that both the femoral and the tibial growth plate remained open. There was no mention of bone age, staging according to the system of Tanner20, height compared with that of grown siblings and parents, or evidence of an adolescent growth spurt. All of these clinical factors must be evaluated to determine whether a patient is a candidate for an operative repair and what the safest operative technique would be to avoid growth disturbances14,19. Nonoperative management of a skeletally immature patient who has a ruptured anterior cruciate ligament may be reasonable if the patient is nearing skeletal maturity. Procedures for stabilizing the extra-articular reconstruction of the anterior cruciate ligament clearly do not have the same reliable results as nearly isometric reconstructions of the ligament15,16. For this reason, McCarroll et al. preferred to wait until the patient was skeletally mature before performing a definitive isometric reconstruction of the anterior cruciate ligament15. The patient in the present study had one month of rehabilitation after the injury and regained a full range of motion of the knee. Bracing and alteration of sports activities until skeletal maturity were not mentioned as alternative forms of treatment. To the best of our knowledge, the technique that was used by the treating surgeon has never been studied in skeletally immature patients. It has some potential complications when used in knees that have open growth plates, and these complications are well illustrated in the present case report. Placement of the transverse femoral fixation screw within the femoral growth plate and the use of bone plugs in the femoral and tibial tunnels are likely to create an epiphyseodesis. Regardless of the technique used, it seems reasonable to avoid placing any screw or bone across an open growth plate. Hardware should be placed in metaphyseal or epiphyseal bone away from the growth plate. The question as to why there was no growth arrest on the tibial side remains unanswered. Perhaps the central location of the tibial tunnel decreased the chance of growth arrest. In immature patients who have a concomitant menisical tear, reconstruction of the anterior cruciate ligament is generally considered in order to avoid additional meniscal damage and progressive articular damage. Physeal-sparing techniques that address the isometry of the anterior cruciate ligament have been described. Parker et al. placed grooves in the tibial epiphysis and the lateral aspect of the distal femoral metaphysis17. The results were encouraging, but the study included a small number of patients and had a relatively short period of follow-up. This technique may provide a reasonable, if not ideal, alternative. Careful evaluation of a skeletally immature patient who has a ruptured anterior cruciate ligament is mandatory because an incomplete preoperative skeletal assessment and an inappropriate operative technique may have catastrophic consequences. Transphyseal intra-articular reconstruction of the anterior cruciate ligament appears to be safe in patients who are approaching skeletal maturity. The risk of physeal injury is reduced, and results paralleling those of reconstructions in adults have been reported15. In younger patients, crossing the growth plates with bone plugs or hardware is contraindicated. The drilling of open growth plates and the interposition of soft tissue seems to cause limited disturbance of the growth plates, but the potential for this complication remains a concern10,13,18. We believe that, if at all possible, reconstruction of a ruptured anterior cruciate ligament should be delayed until the patient reaches skeletal maturity15.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
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