Degenerative changes in cartilage likely occur in the medial compartment after anterior cruciate ligament reconstruction.

PURPOSE: Magnetic resonance imaging with T1ρ mapping is used to quantify the amount of glycosaminoglycan in articular cartilage, which reflects early degenerative changes. The purposes of this study were to evaluate early degenerative changes in knees after anterior cruciate ligament (ACL) reconstruction by comparing T1ρ values before and 2 years after surgery and investigate whether surgical factors and clinical outcomes are related to differences in T1ρ values. METHODS: Fifty patients who underwent unilateral primary ACL reconstruction were evaluated using T1ρ mapping before and 2 years after surgery. Three regions of interest (ROIs) were defined in the cartilage associated with the medial (M) and lateral (L) weight-bearing areas of the femoral condyle (FC) (anterior: MFC1 and LFC1, middle: MFC2 and LFC2, and posterior: MFC3 and LFC3). Two ROIs associated with the tibial plateau (T) were defined (anterior: MT1 and LT1, and posterior: MT2 and LT2). T1ρ values within the ROIs were measured before and 2 years after surgery and compared using the paired t test. Correlations between the difference in T1ρ values at these two time points and patient characteristics, presence of a cartilaginous lesion, graft type, and postoperative anteroposterior laxity were also evaluated using Pearson's and Spearman's correlation coefficients. RESULTS: There was a significant increase in T1ρ before versus 2 years after surgery in the MT1, MT2, LFC1, and LT1 areas, and a significant decrease in the LFC3 and LT2 areas. There was a significant correlation between postoperative anterior-posterior laxity and a postoperative increase in T1ρ values in the MFC3 (r = 0.37, P = 0.013) and MT2 (r = 0.35, P = 0.021) areas. Increases in T1ρ values in the MFC2 area were negatively correlated with KOOS symptoms (ρ = - 0.349, P = 0.027) and quality of life (ρ = - 0.374, P = 0.017) subscale scores. CONCLUSION: Early degenerative changes in medial articular cartilage were observed with T1ρ mapping at 2 years after ACL reconstruction. Postoperative anterior-posterior laxity is correlated with an increase in T1ρ values in the posteromedial femur and tibia. An increase in T1ρ values in the central medial femoral condyle was associated with knee symptoms. LEVEL OF EVIDENCE: III.

Comparison of graft bending angle during knee motion after outside-in, trans-portal and trans-tibial anterior cruciate ligament reconstruction.

PURPOSE: To determine graft bending angle (GBA) during knee motion after anatomic anterior cruciate ligament (ACL) reconstruction and to clarify whether surgical techniques affect GBA. Our hypotheses were that the graft bending angle would be highest at knee extension and the difference of surgical techniques would affect the bending steepness. METHODS: Eight healthy volunteers with a mean age of 29.3 ± 3.0 years were recruited and 3D MRI knee models were created at three flexion angles (0°, 90° and 130°). Surgical simulation of the tunnel drilling was performed with anatomic tunnel position using each outside-in (OI), trans-portal (TP) and trans-tibial (TT) techniques on the identical cases. The models were matched to other knee positions and the GBA in 3D was measured using computational software. Double-bundle ACL reconstruction was analysed first, and single-bundle reconstruction was also analysed to evaluate its effect to reduce GBA. A repeated-measures ANOVA was used to compare GBA difference at three flexion angles, by three techniques or of three bundles. RESULTS: GBA changed substantially with knee motion, and it was highest at full extension (p < 0.001) in each surgical technique. OI technique exhibited highest GBA for anteromedial bundle (94.3° ± 5.2°) at extension, followed by TP (83.1° ± 6.5°) and TT (70.0° ± 5.2°) techniques (p < 0.01). GBA for posterolateral bundle at extension were also high in OI (84.6° ± 7.4°), TP (83.0° ± 6.3°) and TT (77.2° ± 7.0°) techniques (n.s.). Single-bundle grafts did not decrease GBA compared with double-bundle grafts. In OI technique, a more proximal location of the femoral exit reduced GBA of each bundle at extension and 90° flexion. CONCLUSION: A significant GBA change with knee motion and considerably steep bending at full extension, especially with OI and TP techniques, were simulated. Although single-bundle technique did not reduce GBA as seen in double-bundle technique, proximal location of femoral exits by OI technique, with tunnels kept in anatomic position, was effective in decreasing GBA at knee extension and flexion. For clinical relevance, high stress on graft and bone interface has been suggested by steep GBA at full extension after anatomic ACL reconstruction. LEVEL OF EVIDENCE: Therapeutic study (prospective comparative study), Level II.

Optimal entry position on the lateral femoral surface for outside-in drilling technique to restore the anatomical footprint of anterior cruciate ligament.

PURPOSE: To investigate the optimal starting points for drilling on the lateral femoral condyle for better coverage of the anatomical footprint of the anterior cruciate ligament (ACL) using the outside-in (OI) technique in a single-bundle ACL reconstruction. METHODS: Femoral tunnel drilling was simulated on three-dimensional bone models from 40 subjects by connecting the centre of the ACL footprint with various points on the lateral femoral surface. The percentage of the femoral footprint covered by apertures of the virtual tunnel sockets with 9 mm diameter was calculated for each tunnel. RESULTS: The mean percentages of the femoral footprint covered by the apertures of the virtual tunnel sockets were significantly higher when drilled at 2 and 3 cm from the lateral epicondyle on a 45° line and a 60° line anterior from the proximal-distal axis than the other points. However, articular cartilage damage was occurred in nine subjects at 3 cm on a 60° line and eight subjects at 3 cm on a 45° line. Posterior wall blowout occurred in five subjects at 3 cm on a 45° line. Thus, OI drilling at 3 cm from the epicondyle has a risk of these complications. CONCLUSION: During the OI drilling of the femoral tunnel, connecting the centre of the anatomical footprint of the ACL and the entry drilling point at 2 cm from the lateral epicondyle on between the 45° line and the 60° line anterior from the proximal-distal axis provides an oval-shaped socket aperture that covers and restores the native ACL footprint as nearly as possible. LEVEL OF EVIDENCE: III.

Overestimation of femoral tunnel length during anterior cruciate ligament reconstruction using the retrograde outside-in drilling technique.

PURPOSE: When the femoral tunnel socket is reamed in an oblique direction from the wall of inter-condylar notch in anterior cruciate ligament (ACL) reconstruction, the tunnel length can be shorter at the periphery than at the centre. Because surgeons can manipulate the direction of tunnel in the outside-in femoral tunnel drilling technique, this length mismatch would vary depending on the direction of the tunnel. The purpose of this study was to investigate this length mismatch when reamed in various directions. METHODS: In total of thirteen points were defined as femoral drilling entry points on concentric lines with 0, 1, 2, and 3 cm radius from the lateral epicondyle of a three-dimensional bone model from 40 subjects. Femoral tunnel drilling was simulated on the models by connecting the centre of the ACL footprint with each defined point on the lateral femoral surface. The mismatch length was measured between the centre and the shortest peripheral side of the tunnel socket. RESULTS: When the distance between the drilling entry point on the lateral femoral surface and the lateral epicondyle was increased to anterior proximal direction, there was a significant increase in the mismatch length. The mismatch length became more than 2 mm when the entry point was located more than 2 cm away from the lateral epicondyle. CONCLUSIONS: When the drilling entry point is set far away from the lateral epicondyle, a significant increase was observed in tunnel length mismatch between the centre of the tunnel and its shortest peripheral side. Because the tunnel length is measured with a guide pin introduced at the centre of the tunnel before reaming in retrograde outside-in technique, this length mismatch could cause an overestimation of the tunnel length. Surgeons should recognise this mismatch when preparing the length of graft and socket to optimise the graft insertion length into the socket.

Detection of early cartilage deterioration associated with meniscal tear using T1ρ mapping magnetic resonance imaging.

BACKGROUND: In patients with degenerative meniscal tears, subclinical cartilage degeneration may be present even if gross morphological changes are not evident. The aim of this study was to detect occult cartilage degeneration using T1ρ MRI mapping in patients with meniscal tears without obvious radiographic osteoarthritis (OA). METHODS: A total of 22 subjects with degenerative meniscal tears in the early stages of osteoarthritis [Kellgren-Lawrence (KL) grade of 0-2] and 19 healthy subjects as the control group were examined. The femoral condyle was divided into four 30° wedges (-30°-0° anteriorly, 0°-30°, 30°-60° and 60°-90° posteriorly), and each area of cartilage was further divided into superficial and deep layers of equal thickness. The tibial side was divided into anterior and posterior areas with superficial and deep layers in each. The mean T1ρ values (ms) in each area were calculated. RESULTS: On the femoral side, T1ρ values of the superficial and deep regions (-30°-0°, 0°-30° and 30°-60°) in the meniscal tear group were significantly higher than those in the control group [superficial (-30°-0°): 49.0 ± 4.0 (meniscal tear group) vs 45.1 ± 2.1 (control group), deep (-30°-0°): 45.2 ± 3.3 vs 39.5 ± 5.0, superficial (0°-30°): 54.5 ± 5.3 vs 47.4 ± 5.7, deep (0°-30°): 46.8 ± 4.0 vs 40.7 ± 6.3, superficial (30°-60°): 50.5 ± 3.1 vs 47.1 ± 5.7]. On the tibial side, the meniscal tear group had significantly higher T1ρ values superficially in both anterior and posterior regions compared with the control group [superficial (anterior): 52.0 ± 4.3 vs 46.7 ± 5.4, superficial (posterior): 53.1 ± 5.1 vs 46.0 ± 4.9]. Moreover, these significant differences were observed when comparing patients in the meniscal tear group with KL grades of 0 or 1 and the control group. CONCLUSIONS: Our study suggested that early biochemical changes in cartilage associated with degenerative meniscal tears occur first in the superficial zones in areas of contact during slight flexion. Characterising the early relationship between cartilage degeneration and degenerative meniscal tears using T1ρ MRI mapping may be of clinical benefit and provide further evidence linking meniscal injury to OA.

Asymmetry in Femoral Tunnel Socket Length During Anterior Cruciate Ligament Reconstruction With Transportal, Outside-In, and Modified Transtibial Techniques.

PURPOSE: To investigate the mismatch between the length at the center and the length on the shortest and longest peripheral sides of the femoral tunnel socket, reamed with the transportal (TP), outside-in (OI), and modified transtibial (TT) techniques, in anterior cruciate ligament (ACL) reconstruction. METHODS: Femoral tunnel drilling was simulated on 3-dimensional bone models from 40 subjects. The tunnel directions used with the TP, OI, and modified TT techniques were previously described. By use of the resulting angle, a femoral tunnel socket of 9 mm in diameter was drilled from the center of the femoral ACL insertion. The virtual femoral tunnel was extracted, and the length mismatch was measured between the center and the shortest and longest peripheral sides of the tunnel socket. RESULTS: The mean socket length mismatch between the center and the shortest peripheral part of the femoral tunnel socket was 4.2 ± 0.9 mm with the TP technique, 5.2 ± 1.3 mm with the OI technique, and 3.2 ± 0.8 mm with the modified TT technique. The mean socket length mismatch between the center and the longest peripheral part of the femoral tunnel socket was 3.5 ± 0.9 mm with the TP technique, 4.8 ± 1.5 mm with the OI technique, and 3.3 ± 1.2 mm with the modified TT technique. The length mismatch was significantly higher when the tunnel socket was created by the OI technique (P < .01). CONCLUSIONS: A length mismatch with the tunnel socket exists after reaming with either the TP, OI, or modified TT technique. In particular, there was a significant increase in length mismatch when the tunnel socket was created by the OI technique, and the length mismatch would easily become greater than 5 mm. The surgeon should recognize this mismatch when it is created and measure the femoral tunnel socket. CLINICAL RELEVANCE: In anatomic ACL reconstruction, a mismatch between the length at the center and the length at periphery of the femoral tunnel socket occurs, and this is increased particularly when using the OI technique. The discrepancy in tunnel length between its center and its periphery could cause an overestimation of the tunnel length that could result in an error in length during graft preparation.

Influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament reconstruction with anteromedial portal technique.

PURPOSE: To evaluate the influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament (ACL) reconstruction with the anteromedial (AM) portal technique. METHODS: We recruited 6 volunteers with 12 normal knees. Each knee was flexed 120° or 135° and scanned with an open MRI. A 3D knee model was created. Virtual femoral tunnels were created on the footprint of the AM bundle and the posterolateral (PL) bundle of the ACL from three arthroscopic portals: the standard AM portal, the far medial and low portal, and the far medial and high (FMH) portal. The location of the femoral tunnel outlet was evaluated by comparing to the dissected cadaveric knee. RESULTS: Both increased flexion angle and lowering the drilling portal have a similar influence on the femoral tunnel outlet by moving them anterior and distally. Medialization of the portal moves them posteriorly and distally. PL tunnels created on the 120° knee model are more likely to be located under the lateral head of the gastrocnemius especially when they are drilled through the AM or FMH portals. CONCLUSION: If the femoral tunnel outlet is located under the soft tissue such as gastrocnemius attachment, suspension fixation devices may lapse into fixation failure by sitting on the soft tissue rather than the cortex bone surface. It is more desirable to drill in 135° knee flexion rather than 120°, and through a lower portal, to avoid creating the femoral tunnel outlet under soft tissues.

Subclinical cartilage degeneration in young athletes with posterior cruciate ligament injuries detected with T1ρ magnetic resonance imaging mapping.

PURPOSE: Prediction of the risk of osteoarthritis in asymptomatic active patients with an isolated injury of the posterior cruciate ligament (PCL) is difficult. T1ρ magnetic resonance imaging (MRI) enables the quantification of the proteoglycan content in the articular cartilage. The purpose of this study was to evaluate subclinical cartilage degeneration in asymptomatic young athletes with chronic PCL deficiency using T1ρ MRI. METHODS: Six athletes with chronic PCL deficiency (median age 17, range 14-36 years) and six subjects without any history of knee injury (median age 31.5, range 24-33 years) were recruited. Regions of interest were placed on the articular cartilage of the tibia and the distal and posterior areas of the femoral condyle, and T1ρ values were calculated. RESULTS: On stress radiographs, the mean side-to-side difference in posterior laxity was 9.8 mm. The T1ρ values at the posterior area of the lateral femoral condyle and the superficial layer of the distal area of the medial and lateral femoral condyle of the patients were significantly increased compared with those of the normal controls (p < 0.05). At the tibial plateau, the T1ρ values in both the medial and lateral compartments were significantly higher in patients compared with those in the normal controls (p < 0.05). CONCLUSION: T1ρ MRI detected unexpected cartilage degeneration in the well-functioning PCL-deficient knees of young athletes. One should be alert to the possibility of subclinical cartilage degeneration even in asymptomatic patients who show no degenerative changes on plain radiographs or conventional MRI. LEVEL OF EVIDENCE: IV.

Femoral tunnel apertures on the lateral cortex in anterior cruciate ligament reconstruction: an analysis of cortical button fixation.

PURPOSE: If the aperture of the oval-shaped femoral tunnel on the lateral cortex becomes bigger than half the size of the cortical button, the risk of fixation failure increases. This study investigated the effect of the location of the entry point and diameter of the femoral tunnel on the length of the major axis of the tunnel aperture in anterior cruciate ligament (ACL) reconstruction using an outside-in technique. METHODS: Simulation of femoral tunnel drilling was performed on computed tomography (CT)-based 3-dimensional (3D) bone models obtained from 40 participants. The tunnel connected the center of the ACL footprint and various points on the lateral femoral surface. The diameter of the tunnel was set at 4.2 mm, 5.2 mm, or 6 mm, depending on the commercially available outside-in surgical systems (Arthrex, Naples, FL and Smith & Nephew, Andover, MA). The length of the major axis of the oval-shaped aperture on the lateral femoral surface was measured. RESULTS: When the tunnel was introduced at 2 cm from the lateral epicondyle in a 45° anteroproximal direction, the major axis was lengthened to 130.7% ± 9.0% (P < .001) of the tunnel diameter, and it was more than 6.5 mm in 65% of participants in whom a 5.2-mm-diameter tunnel was drilled. When the entry point was 3 cm from the lateral epicondyle, 60% of participants had an oval-shaped aperture with a major axis of more than 6.5 mm, even though the diameter of the tunnel was only 4.2 mm. CONCLUSIONS: The risk of fixation failure of a cortical button increases if the entry point for drilling is 2 cm or further from the lateral epicondyle and the tunnel diameter is more than 5 mm. CLINICAL RELEVANCE: This study indicates the potential risk of cortical button fixation failure caused by an oval tunnel aperture on the lateral femoral surface in ACL reconstruction using the outside-in technique.

Use of venovenous extracorporeal membrane oxygenation for perioperative management of acute respiratory distress syndrome caused by fat embolism syndrome: A case report and literature review.

INTRODUCTION: Fat embolism syndrome (FES) is a known complication of long bone fracture and can affect multiple organs. The organ most commonly affected with FES is the lung. Severe cases of FES from long bone fracture can cause acute respiratory distress syndrome (ARDS). Although the treatment of ARDS remains challenging, it is reported that a lung protection strategy and prone positioning are effective. In addition, early fixation is reported to be beneficial in respiratory failure due to FES, though it may exacerbate respiratory failure during the perioperative period. We report the use of venovenous extracorporeal membrane oxygenation (VV-ECMO) for the successful perioperative management of a patient diagnosed with ARDS due to FES. PATIENT CONCERNS: A 24-year-old man injured in a traffic accident was brought to our emergency department due to shock and consciousness disorder. DIAGNOSIS: After examining the patient, we noted bilateral pneumothorax, liver and spleen injuries, and multiple long bone fractures. Four days after admission, he was diagnosed with FES due to a prolonged consciousness disorder, progressive hypoxia with diffuse lung damage, and cutaneous and mucosal petechiae. INTERVENTION: As respiratory failure progressed, VV-ECMO was initiated on the 6th day. To improve the respiratory failure caused by ARDS, prone position therapy was necessary. Thus, we performed osteosynthesis on the 9th day under ECMO. Prone position therapy was started after surgery. OUTCOMES: Subsequently, his respiratory condition and chest radiographs improved steadily. VV-ECMO was discontinued on the 17th day and the ventilator was removed on the 28th day. His consciousness levels improved without residual central nervous system complications. CONCLUSION: Our study reveals the successful improvement of FES-induced ARDS by osteosynthesis and prone positioning under VV-ECMO. This strategy prioritizes supportive treatment over pharmacologic interventions.

Anterolateral rotatory instability in vivo correlates tunnel position after anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft.

AIM: To quantitatively assess rotatory and anterior-posterior instability in vivo after anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BTB) autografts, and to clarify the influence of tunnel positions on the knee stability. METHODS: Single-bundle ACL reconstruction with BTB autograft was performed on 50 patients with a mean age of 28 years using the trans-tibial (TT) (n = 20) and trans-portal (TP) (n = 30) techniques. Femoral and tibial tunnel positions were identified from the high-resolution 3D-CT bone models two weeks after surgery. Anterolateral rotatory translation was examined using a Slocum anterolateral rotatory instability test in open magnetic resonance imaging (MRI) 1.0-1.5 years after surgery, by measuring anterior tibial translation at the medial and lateral compartments on its sagittal images. Anterior-posterior stability was evaluated with a Kneelax3 arthrometer. RESULTS: A total of 40 patients (80%) were finally followed up. Femoral tunnel positions were shallower (P < 0.01) and higher (P < 0.001), and tibial tunnel positions were more posterior (P < 0.05) in the TT group compared with the TP group. Anterolateral rotatory translations in reconstructed knees were significantly correlated with the shallow femoral tunnel positions (R = 0.42, P < 0.01), and the rotatory translations were greater in the TT group (3.2 ± 1.6 mm) than in the TP group (2.0 ± 1.8 mm) (P < 0.05). Side-to-side differences of Kneelax3 arthrometer were 1.5 ± 1.3 mm in the TT, and 1.7 ± 1.6 mm in the TP group (N.S.). Lysholm scores, KOOS subscales and re-injury rate showed no difference between the two groups. CONCLUSION: Anterolateral rotatory instability significantly correlated shallow femoral tunnel positions after ACL reconstruction using BTB autografts. Clinical outcomes, rotatory and anterior-posterior stability were overall satisfactory in both techniques, but the TT technique located femoral tunnels in shallower and higher positions, and tibial tunnels in more posterior positions than the TP technique, thus increased the anterolateral rotation. Anatomic ACL reconstruction with BTB autografts may restore knee function and stability.

Characterization of Biochemical Cartilage Change After Anterior Cruciate Ligament Injury Using T1ρ Mapping Magnetic Resonance Imaging.

BACKGROUND: Patients with anterior cruciate ligament (ACL)-injured knees are at an increased risk of posttraumatic osteoarthritis (OA). OA changes secondary to ACL injuries have many variations, and when and where early cartilage degenerative change begins has not yet been established. PURPOSE: To characterize the location of cartilage degeneration after ACL injury associated with time since injury using T1rho (T1ρ) mapping. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: In this study, 49 knees with ACL injuries and 14 normal knees from uninjured volunteers were imaged with a 3.0-T magnetic resonance scanner. Three regions of interest (ROIs) were defined in the cartilage at the weightbearing area of the femoral condyles (anterior, middle, and posterior zones). Two ROIs were defined in the tibial plateau (anterior and posterior zones). The T1ρ values within the ROIs were measured. Patients were allocated into 3 groups based on time since injury: <12 weeks (group A; 28 patients), 12 weeks to 2 years (group B; 14 patients), and >2 years to 5 years (group C; 7 patients). RESULTS: Mean T1ρ values were significantly greater in the anterior and middle ROIs of the medial femoral condyle in group C compared with those in other groups (P < .05). Patients with medial meniscus injury, for whom the time since injury was ≥12 weeks, exhibited significantly greater T1ρ values in the middle areas of the medial femoral condyle versus normal knees and ACL-injured knees without medial meniscus injury. CONCLUSION: The risk of cartilage degeneration in the area of the femoral condyle that contacts the tibia during small degrees of flexion increased when the time since injury was longer than 2 years. In addition, medial meniscus injury was associated with cartilage degeneration at the medial femoral condyle in the chronic phase. CLINICAL RELEVANCE: Cartilage degeneration occurs more than 2 years after ACL injury and increases with medial meniscus injury. Early intervention may be desirable for meniscus injury.

Comparison of transtibial and transportal techniques in drilling femoral tunnels during anterior cruciate ligament reconstruction using 3D-CAD models.

PURPOSE: The purpose of this study was to assess the differences in bone tunnel apertures between the trans-accessory medial portal (trans-AMP) technique and the transtibial (TT) technique in double-bundle anterior cruciate ligament reconstruction. The extent of ovalization and the frequency of overlap of the two tunnel apertures were compared. METHODS: The simulation of femoral tunnel drilling with the TT and the trans-AMP techniques was performed using three-dimensional computer aided design models from two volunteers. The incidence angle of drilling against the intercondylar wall, the femoral tunnel position, the ovalization, and the overlap were analyzed. The aperture and location of the tunnels were also examined in real anterior cruciate ligament reconstruction cases (n=36). RESULTS: The surgical simulation showed that a lower drill incident angle induced by the TT technique made the apertures of two tunnels more ovalized, located anteromedial tunnels in a shallower position to prevent posterior wall blow out, and led to a higher frequency of tunnel overlap. The trans-AMP group had tunnel places within the footprint and had less ovalization and overlap. The results of analysis for tunnels in the clinical cases were consistent with results from the surgical simulation. CONCLUSION: In the TT technique, the shallow anteromedial tunnel location and more ovalized tunnel aperture can lead to a higher frequency of tunnel overlap. Compared with the TT technique, the trans-AMP technique was more useful in preparing femoral tunnels anatomically and avoiding tunnel ovalization and overlapping in double-bundle anterior cruciate ligament reconstruction.