Can magnetic resonance imaging findings predict the degree of knee joint laxity in patients undergoing anterior cruciate ligament reconstruction?

BACKGROUND: The present study was performed to determine whether MRI findings can predict the degree of knee joint laxity in patients undergoing ACL reconstruction and whether the accuracy of the prediction is affected by the MRI acquisition time. METHODS: We assessed prospectively collected data of 154 knees with ACL tears. The presence or absence of four primary findings of ACL tears, i.e., nonvisualization, discontinuity, abnormal signal intensity, and abnormal shape of the ACL, and five secondary findings, i.e., anterior translation of the tibia relative to the femur (≥7 mm), posterior cruciate ligament angle (<105°), bone contusion, Segond fracture, and the deep sulcus sign, were determined. Knee joint laxity was assessed using the Lachman and pivot shift tests. The associations between MRI findings and clinically assessed knee joint laxity were analyzed and compared between subgroups (≤3 months from injury to MRI, 89 knees; >3 months, 65 knees). RESULTS: Nonvisualization was related to the results of the Lachman test [Odds ratio (OR), 2.6; 95% confidence interval (CI), 1.2-5.5]. Anterior translation of the tibia relative to the femur was related to the results of the pivot shift test (OR, 3.8; 95% CI, 1.6-9.4). In subgroup comparisons of the early and late MRI groups, anterior translation of the tibia relative to the femur was related to the results of the pivot shift test in the early MRI group (OR, 4.5; 95% CI, 1.4-14.4). In contrast, no MRI findings had statistically significant relationships with physical findings in the late MRI group. CONCLUSIONS: Our study indicates that MRI findings may have some usefulness for predicting the grade of knee laxity in patients with symptomatic ACL injury, but its value is limited, especially in patients with a longer time interval between injury and the performance of MRI.

Coronal limb alignment and indications for high tibial osteotomy in patients undergoing revision ACL reconstruction.

BACKGROUND: Failed ACL reconstruction frequently is accompanied by irreparable medial meniscal tear and/or visible osteoarthritis (OA) in the medial tibiofemoral joint. Thus, assessment for the presence of varus malalignment is important in caring for patients in whom revision ACL reconstruction is considered. QUESTIONS/PURPOSES: We determined whether patients undergoing revision ACL reconstruction (1) have more frequent varus malalignment coupled with more severe degrees of medial meniscal injury and/or medial tibiofemoral OA, and (2) would meet potential indications for high tibial osteotomy more frequently than patients undergoing primary ACL reconstruction. METHODS: We compared 58 patients undergoing revision ACL reconstruction and 116 patients undergoing primary ACL reconstruction. The mechanical tibiofemoral angle and the weight loading line (%) of the knee were measured. Additionally, radiographic degrees of OA in the tibiofemoral joints, and meniscal conditions were assessed. Then, proportions of potential candidates for high tibial osteotomy between the two groups were compared based on the following indications: (1) weight loading line less than 5%, (2) weight loading line less than 25% and medial tibiofemoral OA Kellgren-Lawrence Grade 3 or greater, or (3) weight loading line less than 25% and Kellgren-Lawrence Grade 2 medial tibiofemoral OA plus subtotal or total medial meniscectomy status. RESULTS: The revision ACL reconstruction group had more frequent varus malalignment in terms of proportion of knees with more varus mechanical tibiofemoral angle than varus 5° (19% versus 8%, p = 0.029) and knees with weight loading line less than 25% (22% versus 9%, p = 0.011). This group also had more frequent high-grade injury of the medial meniscus (34% versus 16%, p = 0.007) and tended to have more frequent higher-grade radiographic OA at the medial tibiofemoral joint (19% versus 9%, p = 0.076). The percentage of patients meeting potential indications for high tibial osteotomy was greater in this group (14% versus 2%, p = 0.003). CONCLUSIONS: We found that many patients undergoing revision ACL surgery may be reasonable candidates for concurrent high tibial osteotomy to address concomitant alignment and OA issues in the medial compartment. However, whether that additional intervention is offset by added risk and morbidity should be the focus of a future study, as it cannot be answered by a study of this design.

Anteromedial portal versus outside-in technique for creating femoral tunnels in anatomic anterior cruciate ligament reconstructions.

PURPOSE: To determine whether the anteromedial (AM) portal and outside-in techniques in anterior cruciate ligament reconstruction differ (1) in the coronal femoral tunnel position, (2) in the femoral tunnel length, and (3) in the incidence of femoral tunnel-related complications, such as femoral socket blowout. METHODS: We examined 63 knees undergone primary anterior cruciate ligament reconstructions using the AM portal technique (AM portal group) and 54 knees using the outside-in technique (outside-in group). Coronal femoral tunnel positions between the 2 groups were assessed on postoperative tunnel-view radiographs and compared. Comparisons of femoral tunnel lengths, proportions of knees with a femoral tunnel length of less than 30 mm, and incidences of femoral tunnel-related complications were performed between the 2 groups. RESULTS: There were no significant differences in coronal femoral tunnel positions between the AM portal and outside-in groups (56.6° v 56.4°, P > .99). Differences in femoral tunnel lengths between the AM portal and outside-in groups did not reach statistical significance (37.6 mm and 39.0 mm, respectively; P = .097), but the tunnel length of the outside-in group showed smaller variation than that of the AM portal group in terms of standard deviation (2.7 v 6.0). In addition, the AM portal group had a significantly greater proportion of knees with a femoral tunnel length of less than 30 mm than the outside-in group (14% v 0%, P = .004). There were 2 tunnel-related complications (3%) (highly suspicious cortical blowouts) in the AM portal group and none in the outside-in group (P = .499). CONCLUSIONS: This study shows that compared with the AM portal technique, the outside-in technique can achieve a similar femoral tunnel position in the coronal plane with a reduced chance of a femoral tunnel length of less than 30 mm. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Use of simple algorithms to predict screw length facilitates navigation-controlled medial opening-wedge osteotomy using the TomoFix HTO system.

This study was performed to establish simple algorithms to predict proper screw lengths for the 4 proximal holes of TomoFix plates (Synthes GmbH; Solothurn, Switzerland) based on radiographic mediolateral (ML) and anteroposterior (AP) dimensions of the proximal tibia and to determine how well these algorithms function for navigation-controlled medial opening-wedge high tibial osteotomy (HTO) using TomoFix. Experimental HTO surgery was performed in proximal tibial models manufactured for 30 patients undergoing HTO to determine the longest screw lengths for the 4 proximal holes of TomoFix plates. Eight algorithms were created for the 4 proximal screws by investigating the relationships between measured screw lengths and radiographic dimensions and were used for 30 navigation-controlled medial opening-wedge HTOs. The algorithms used to predict screw length were: screw A=ML width-20 mm and AP length+5 mm; screw B=ML width-25 mm and AP length; screw C=ML width-35 mm and AP length-10 mm; and screw D=ML width-40 mm and AP length-15 mm. All 30 surgeries were performed with no perioperative adverse events. Mean operative time was 47.1 minutes, and no far cortex perforation of more than 3 mm was observed for any of the 4 proximal screws. Mean mechanical tibiofemoral angle and weight load line coordinate at the knee joint were valgus 3.7° and 62.9%, respectively. Targeted alignment was achieved in 28 (93%) knees for a mechanical tibiofemoral angle between valgus 2° and 6°, and in 25 (83%) knees for a weight load line coordinate between 55% and 70%. The authors propose the use of the developed algorithms to select proper screw lengths for medial opening wedge HTO using the TomoFix HTO system.