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The anterior cruciate ligament (ACL) is frequently injured during both recreational and competitive activity. It is common to see patients who have ruptured both ACLs at different times. Intercondylar notch width, notch morphology, gender, and family history have all been implicated as factors that may predispose an individual to contralateral ACL rupture following unilateral injury. Simultaneous bilateral ACL rupture is a rare occurrence. Only 1 other case has previously been reported. We report the case of a 17-year-old high school cheerleader who sustained simultaneous bilateral ACL ruptures. Some of the commonly implicated risk factors for ACL rupture are examined and a review of the literature is also presented.

A matrix of demineralized cortical bone was used to reconstruct the anterior cruciate ligament in the goat model. This graft underwent considerable site-specific remodeling and transformation from a Haversian system at time zero into a ligament-like structure at 1 year. This transformation included new bone formation filling the osseous tunnels and replacing the demineralized matrix, development of a ligament-like transition zone within the graft, and ligamentous collagen orientation with crimp in the intraarticular portion of the graft. One year after surgery, the mean anterior-posterior translation in the reconstructed stifle joints at 30 N of tibial loading was 2.1 +/- 0.4 (+/- SEM). The mean ultimate force to failure for the reconstructed ligament at 1 year was 474 +/- 146 N compared with the time-zero (initial) strength of the matrix of 73 +/- 9 N. The cellular repopulation of the graft had no associated inflammatory cells. The potential clinical significance of these findings includes 1) replacement of a collagen matrix with bone within the osseous tunnels, 2) establishment of a more physiologic fibrocartilage transition at the graft insertion site, 3) the time-zero structural properties of a collagen matrix increasing to more desired values with biologic remodeling, and 4) a sterile biologic allograft with essentially no long-term inflammatory response.

MR imaging of the anterior cruciate ligament (ACL) can provide highly accurate information and is the most diagnostic current imaging procedure for suspected injuries to the ligament. It is safe, absent of ionizing radiation, non-invasive, and tolerated well by patients. There have been significant advances in technique and the ability to interpret images. One can expect sensitivities of 92% to 96% and specificities of 92% to 98%. This imaging test of the ACL can provide useful information in establishing the normal anatomy, diagnosing tears, and studying the reconstructed graft.

The replacement tissue used for anterior cruciate ligament reconstruction undergoes extensive biologic remodeling and incorporation after implantation. Successful biologic incorporation of the graft is dependent on a number of factors including graft placement, tensioning, and the nature of the tissue (allograft versus autograft). Failure of an anterior cruciate ligament reconstruction may occur on the basis of either technical, mechanical, or biological factors. Biologic factors include cellular repopulation, matrix remodeling, the ultimate small diameter collagen fibril orientation, the final cross sectional area of the graft, a favorable vascularization, and not overloading the graft during the remodeling process. The fully incorporated graft never duplicates the native anterior cruciate ligament but works as a check reign that makes the knee more functional.

Soft tissue allografts allow the orthopaedic surgeon to reconstruct ligaments without having to harvest additional tissue from the patient, which can eliminate donor tissue site morbidity and reduce surgical time. There is still much to be learned about the biologic aspects of the remodeling and incorporation of allografts in comparison with autografts. The interaction of cells, matrix, and biomolecules, such as growth factors, plays an important role that can potentially modulate, enhance, or impede the healing response in allografts. The authors have shown that, in the short term, allografts used in anterior cruciate ligament reconstruction are not as rapidly remodeled and incorporated into host tissue as are autografts. The long-term implications of this slower allograft incorporation in anterior cruciate ligament reconstruction are still unknown. The cells that repopulate allografts and autografts favor production of smaller diameter collagen fibrils, which in sufficient numbers can provide significant strength. Use of allografts raises other issues and potential disadvantages, including scarcity, immunogenicity, the potential for disease transmission, and cost-effectiveness in anterior cruciate ligament reconstruction.

Similar-sized patellar tendon autografts and fresh-frozen allografts were used to reconstruct the anterior cruciate ligament of one knee in 40 female goats. Evaluations of the reconstructions and contralateral controls at the 6-week and 6-month postoperative periods included anterior-posterior translation, mechanical properties determined during tensile failure tests, measurement of cross-sectional area, histology, collagen fibril size and area distribution, and associated articular cartilage degenerative changes. Six months after anterior cruciate ligament reconstruction, the autografts demonstrated a smaller increase in anterior-posterior displacement, values of maximum force to failure two times greater, a significant increase in cross-sectional area, a more rapid loss of large-diameter collagen fibrils, and an increased density and number of small-diameter collagen fibrils compared to the allografts. Clinical significance. More surgeons are allowing their patients to return to running and sports 6 months after anterior cruciate ligament reconstruction. While the structural and material properties of autografts and allografts at time zero are similar, in the goat model during the first 6 months they differ. The allografts demonstrate a greater decrease in their implantation structural properties, a slower rate of biologic incorporation, and the prolonged presence of an inflammatory response. At 6 months the autograft demonstrates a more robust biologic response, improved stability, and increased strength to failure values.

Seventy-five patients undergoing arthroscopically-assisted anterior cruciate ligament reconstruction by the same surgeon were divided into three random subgroups. All of the anterior cruciate ligament reconstructions used the middle third of the ipsilateral patellar tendon autograft. Patients undergoing meniscal repair, extraarticular procedures, or repair of other ligaments were excluded. The 75 patients were divided into subgroups to assess the benefits or disadvantages of early active motion (25 patients), continuous passive motion (25 patients), and a combination of both (25 patients) during the first 30 days after surgery. All patients were evaluated at specific intervals for 6 months after surgery. Data recorded included drain output, medication usage, tourniquet time, leg involved, hospital stay length, KT-1000 testing (before surgery in the anesthetized patient, after the procedure was completed, and 2 and 6 months after surgery), and range of motion. Radiographs and the International Knee Evaluation Form were also used to evaluate the results. No statistically significant differences were found between the three groups. Side-to-side anterior-posterior differences, stability, and restoration of full range of motion were similar in each subgroup at each evaluated interval. In this prospective study of motion, started immediately after anterior cruciate ligament reconstruction, passive and active methods were shown to have identical results. A supervised active and passive motion program during the 1st month had the same results as either one used individually.

Magnetic resonance images (MRI) were performed within three weeks of anterior cruciate ligament (ACL) rupture on 75 skeletally mature patients. Occult bony lesions were documented in 64 (85%) of the patients. Of the 64 patients with bone injuries, 83% had lesions of the lateral compartment. The lateral femoral condyle was involved in 50%, and the lateral tibial plateau was injured in 50% of the patients with changes. Nineteen of the 64 patients had more than one area of bony injury. Although the majority of bony lesions resolve, permanent alterations remained in some cases. This study has implications that may affect rehabilitation and the long-term prognosis in those patients with extensive bony and associated articular cartilage injuries.