Cartilage thickness in the medial compartment of the knee joint evaluated by MRI three-dimensional analysis correlates with weight-bearing line ratio and joint line convergence angle.

PURPOSE: The correlation between cartilage thickness evaluated by 3D MRI and knee alignment has not been elucidated. The study's purpose was to retrospectively verify whether average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with knee alignment. METHODS: A total of 53 patients underwent medial meniscus repair or high tibial osteotomy for medial knee osteoarthritis. Cartilage thickness was automatically calculated using 3D MRI software. Knee alignment, weight-bearing line ratio (WBLR), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were calculated on a weight-bearing long-leg radiograph using digital planning software. The association between knee alignment and the average cartilage thickness at 18 subregions in the medial femoral condyle (MFC) and medial tibial plateau (MTP) was evaluated using Spearman's rank correlation coefficient. RESULTS: Cartilage thickness of the MFC had moderately positive correlations with WBLR at four subregions and weak correlations at two subregions. Cartilage thickness of the MTP had moderately positive correlations with WBLR at four subregions. Cartilage thickness of the MFC had moderately negative correlations with JLCA at six subregions. Cartilage thickness of the MTP had moderately negative correlations with JLCA at four subregions and a weak correlation at one subregion. Conversely, cartilage thickness had weak correlations with MPTA or LDFA. CONCLUSIONS: In knees with pathological conditions in the medial compartment, cartilage thicknesses by 3D MRI had positive correlations with WBLR and JLCA at almost all subregions of the MFC and at the anterior-middle and central-external of the MTP. Treatment strategies should be considered in light of these regions. LEVEL OF EVIDENCE: Cross-sectional study (diagnosis); Level of evidence, 2.

Augmentation of a Nonanatomical Repair of a Medial Meniscus Posterior Root Tear With Centralization Using Three Knotless Anchors May Be Associated With Less Meniscal Extrusion and Better Compressive Load Distribution in Mid-Flexion Compared With Non-Anatomical Root Repair Alone in a Porcine Knee Model.

PURPOSE: To investigate the biomechanics of the centralization augmentation using knotless soft anchors to a nonanatomical transtibial pull-out root repair in a porcine medial meniscus posterior root tear (MMPRT) model. METHODS: Porcine knee joints (N = 10) were used to perform one of the following procedures: (1) intact; (2) MMPRT; (3) nonanatomical root repair; (4) nonanatomical root repair with centralization using 2 anchors: anchors were inserted at the posterior medial collateral ligament (MCL) border and 10 mm anterior to the posterior MCL border; and (5) nonanatomical root repair with centralization using 3 anchors: another anchor was placed 10 mm posterior to the posterior MCL border. Contact area on the medial meniscus (MM), contact pressure in the MM and tibial cartilage, and MM extrusion were evaluated at 30°, 45°, 60°, and 90° knee flexions under 200 N compressive force. RESULTS: MM extrusion at the posterior MCL border was significantly reduced after root repair with centralization using 3 anchors than after root repair alone at 30° (-0.063 mm vs 1.5 mm, P = .017), 45° (0.21 mm vs 1.7 mm, P = .018), and 60° (0.78 mm vs 2.3 mm, P = .019). There were no significant differences in MM extrusion between the root repair alone and root repair with centralization using 2 anchors at all flexion angles. The contact area in the middle and posterior MM was significantly greater after centralization with 3 anchors than after root repair alone at all flexion angles (except the posterior MM at 90°). The mean contact pressure in the tibial cartilage was significantly lower after centralization with 3 anchors than after root repair at all angles. CONCLUSIONS: Augmentation of a nonanatomical repair of a medial meniscus posterior root tear with centralization using three knotless anchors may be associated with less meniscal extrusion and better compressive load distribution between 30° and 60° flexion compared with nonanatomical root repair alone in a porcine model. CLINICAL RELEVANCE: This biomechanical study at time zero suggests that the addition of centralization using 3 knotless anchors may reduce MM extrusion and restore the load-distributing function of the MM.

Lateral-medial asymmetry of posterior tibial slope and small lateral tibial plateau articular surface depth are morphological factors of lateral meniscus posterior root tears in ACL-injured patients.

PURPOSE: To investigate whether knee morphological features, patient characteristics, and intraoperative findings are associated with a lateral meniscus (LM) posterior root tear (LMPRT) in anterior cruciate ligament (ACL) injuries with the integrated data from two academic centres. METHODS: This retrospective study used registry data acquired prospectively at two academic centres. Patients with ACL reconstruction (ACLR) with LMPRT and no other LM injury were selected (LMPRT group) from each database. The control group included patients who underwent ACLR without LM tears. Patients were matched to the LMPRT group according to age and gender (1:1). Morphological factors evaluated on preoperative magnetic resonance image scans included lateral femoral condyle (LFC) anterior-posterior diameter, height, and depth; lateral tibial plateau (LTP) articular surface (AS) depth and sagittal plane depth; and lateral and medial posterior tibial slopes (PTSs). LFC height and depth ratios, LTP AS depth and sagittal plane depth ratios, and lateral-to-medial slope asymmetry were computed from previous measurements. Patient characteristics and intraoperative findings were extracted and compared between both groups. RESULTS: The study included 252 patients (126 in each group). The lateral-medial asymmetry of PTS was greater in the LMPRT group (1.2° vs 0.3°, p < 0.05), and the LTP AS depth was smaller in the LMPRT group (31.4 mm vs 33.2 mm, p < 0.01). There were no differences in LFC morphology between the control and LMPRT groups. Pivot shift grade (p < 0.05), percentage of complete ACL tears (p < 0.05), and medial meniscus ramp lesions (p < 0.05) were significantly higher in the LMPRT group. CONCLUSION: LMPRT was associated with significantly increased lateral-medial asymmetry of PTS and significantly smaller LTP AS depth. LMPRT was also associated with an increase in the preoperative pivot shift grade and the presence of a medial meniscus ramp lesion. These morphological characteristics are rather simple to measure and would serve as helpful indicators to preoperatively detect LMPRT, which is frequently challenging to diagnose preoperatively. LEVEL OF EVIDENCE: Level III.

Low central sensitisation inventory score is associated with better post-operative outcomes of osteotomy around the knee.

PURPOSE: The purpose of this study was to investigate the potential association between central sensitisation inventory (CSI) scores and post-operative patient-reported outcomes (PROs) in patients underwent osteotomy around the knee (OAK), with a CSI cut-off score specific for knee osteoarthritis. METHODS: CSI scores were collected from 173 patients who underwent OAK, along with their knee injury and osteoarthritis outcome score (KOOS) and pain numeric rating scale (NRS) scores. Patients were divided into high-CSI score group and low-CSI score group with a cut-off score of 17. Multivariate linear regression was performed to test the association between CSI scores and post-operative outcomes. Pre-surgery KOOS and NRS scores and the rate of attainment of minimal clinically important difference (MCID) of KOOS scores was analysed as secondary outcomes. RESULTS: Low-CSI score group had significantly higher post-operative KOOS scores and lower pain NRS scores compared to the high-CSI score group (< p = 0.01) after adjusting for confounding factors. For pre-operative scores, only the KOOS-Symptom score was significantly different between the groups (64.7 ± 20.1 when CSI < 17 vs.55.1 ± 19.7 when CSI ≥ 17; p = 0.008). The low-CSI score group had significantly higher MCID achievement rates of KOOS-Pain, Symptom, and ADL than the high-CSI score group (86% vs. 68%; 74% vs. 55%; 86% vs. 67%, respectively; P < 0.05). CONCLUSIONS: This study established an association between post-operative CSI scores ≥ 17 and poorer outcomes following OAK, highlighting the potential value of the CSI in identifying patients in need of more comprehensive peri-operative pain management. LEVEL OF EVIDENCE: Level III. Retrospective comparative study.

Mid-term clinical outcomes of a posterior stabilized total knee prosthesis for Japanese patients: A minimum follow-up of 5 years.

BACKGROUND: A high-flexion posterior-stabilized total knee prosthesis has been developed for the Asian population. The component design was based on computed tomography images of Japanese osteoarthritic knees. The femoral component is composed of zirconia ceramics, which exhibit low friction and high durability. The present study aimed to evaluate the mid-term clinical outcomes of this implant. METHODS: This study included 334 knees of 210 patients who underwent primary total knee arthroplasty with this implant at our hospital between October 2010 and December 2014. The patients comprised 28 men and 172 women with an average age of 73 years. The average follow-up period was 5.9 years, and the follow-up rate was 71.1%. Clinical outcomes were assessed using the Knee Society scoring system, 2011 Knee Society questionnaire, and Knee Injury and Osteoarthritis Outcome Score. Kaplan-Meier survivorship analysis was performed to determine the cumulative prosthesis survival rate. RESULTS: In terms of clinical outcomes at the final follow-up, the average ranges of motion were -2.0 in extension and 126.7 in flexion. The Knee Society knee and function scores were 94.2% and 72.6%, respectively. With revision surgery or radiographic failure for any reason as the endpoint, the survival rates at 5 and 9 years were 98.2% and 95.5%, respectively. The most common reason for revision surgery or radiological failure was aseptic loosening. CONCLUSIONS: Despite several revision cases mainly due to aseptic loosening, the present study found that this new high-flexion posterior-stabilized total knee arthroplasty prosthesis design showed comparable results for Asian populations with other PS prosthesis. LEVELS OF EVIDENCE: Level Ⅱ (Prospective cohort study).

Suture tape augmentation improves laxity of MCL repair in the ACL reconstructed knee.

PURPOSE: Medial collateral ligament (MCL) injury is very common and surgical repair is sometimes necessary. Especially in the setting of simultaneous anterior cruciate ligament reconstruction (ACLR) as the ACL is the secondary restraint against valgus stress. The goal of this study was to evaluate knee biomechanics after suture repair of the MCL augmented with suture tape, as compared to MCL repair alone, in the setting of concomitant ACL reconstruction (ACLR). METHODS: Fifteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under four loadings: (a) an 89.0 N anterior tibial load, (b) a 5.0 Nm internal and external rotation torque, (c) a 10.0 Nm valgus load, (d) a 7.0 Nm valgus load combined with 5.0 Nm internal rotation torque as a static simulated pivot-shift. The tested conditions were ACLR with the following states: (1) MCL intact, (2) MCL deficient, (3) MCL Repair, and (4) MCL repair augmented with suture tape (MCL Repair + ST). Under the different knee loadings, the tibial displacement, and the force in either the intact MCL, suture repaired MCL or repaired MCL-suture tape complex was measured. RESULTS: While neither the MCL Repair nor the MCL Repair + ST restored valgus rotation to the MCL intact state, displacement was significantly smaller after MCL Repair + ST (p < 0.05). The knee rotation under external rotation torque in MCL Repair + ST did not differ MCL intact (n.s.), while with MCL Repair the rotation was significantly greater (p < 0.05). MCL Repair + ST did not cause an over-constraint of the knee in any of the tested loading conditions. CONCLUSION: In a combined ACL-reconstruction-MCL-repair model, MCL Repair augmented with suture tape improved valgus and external rotation laxity when compared to MCL suture repair alone. Suture tape augmentation may provide this additional means of stabilization and can be added at the time of surgical repair of the MCL. Clinically this may result in lower failure rates and less residual laxity after MCL repair, as well as shorter immobilization times and faster return to play.

Anatomic femoral tunnel placement is difficult by the transtibial technique: comparison of three different femoral tunnel drilling techniques in double-bundle anterior cruciate ligament reconstructions.

PURPOSE: To compare the position and direction of femoral and tibial tunnels for both the anteromedial bundle (AMB) and posterolateral bundle (PLB) among three different femoral tunnel drilling techniques, transtibial (TT), transportal (TP), and outside-in (OI) techniques, in anatomic double-bundle ACL reconstruction to clarify advantages and disadvantages of each technique. METHODS: One-hundred and thirty-nine patients underwent primary ACL reconstruction with an autologous semitendinosus tendon in our institution between 2014 and 2016. Thirteen patients were excluded according to the exclusion criteria. Of the 126 patients, 98 patients agreed to be included in this study. Patients were then randomized into three groups according to the femoral tunnel drilling technique; the TT, TP, and OI groups. Femoral and tibial tunnel angles and positions were measured using three-dimensional computed tomography. RESULTS: Of patients who agreed to be included in this study, eight patients (seven in TT and one in OI) were excluded since the femoral tunnel could not be created at the intended position. Eighty-six patients (29 in TT, 29 in TP, and 28 in OI) were included for the analyses. Tunnel angles, as well as tunnel lengths, had significant differences among different techniques depending on each technique's characteristics. In terms of tunnel position, femoral tunnel positions of both the AMB and PLB in the TT group were significantly higher than those in the TP group (AMB: p = 0.003, PLB: p = 0.001), and the PLB tunnel position in the TP group had significantly smaller vaciance than that in the TT group (p = 0.004) and OI group (0.002). CONCLUSIONS: The femoral tunnel positions created by the TT technique were significantly higher, with larger variance, than the TP technique in double-bundle ACL reconstruction, although the positions seemed to be within anatomical footprint. In addition, there were several cases in which femoral tunnels could not be created at the intended position by the TT technique. LEVEL OF EVIDENCE: I.

Preoperative sonographic measurement can accurately predict quadrupled hamstring tendon graft diameter for ACL reconstruction.

PURPOSE: Previous studies reported sonography was inferior to MRI to predict hamstring tendon graft diameter for ACL reconstruction. This study aimed to investigate the correlation between intraoperative hamstring tendon graft diameter and its preoperative measurement using different sonographic scanning protocol from previous studies. METHODS: Two cadaveric knees were utilized for validation. Sonographically guided gracilis tendon (G) and semitendinosus tendon (ST) injections were performed at myotendinous junction of sartorius using colored latex and then dissection was performed. In the clinical studies, 28 patients underwent primary ACL reconstruction were enrolled. Cross-sectional area (CSA) of G and ST were measured at myotendinous junction of Sartorius. The diameter of doubled G (2G), doubled ST (2ST) and quadrupled ST + G (4STG) were intraoperatively measured using graft sizing devices with 0.5-mm increments. RESULTS: Cadaveric dissection showed the presence of latex on the surface of G and ST at myotendinous junction of Sartorius in all specimens. In the clinical studies, CSA of G, ST, and ST + G significantly correlated with diameter of 2G (r = 0.464, p = 0.039), 2ST (r = 0.712, p < 0.001), and 4STG (r = 0.792, p < 0.001), respectively. As a result of the simple linear regression analysis, 4STG diameter could be predicted by the following formula: 4.345 + 0.210 × CSA. The differences between calculated diameter by this formula and intraoperative 4STG diameter were within ± 0.5 mm in 89.3% (25/28) of subjects. CONCLUSIONS: The diameter of 2ST and 4STG can be reliably predicted based on sonographic CSA measurement preoperatively. Sonography is a cost-effective alternate to repeat MRI to predict hamstring graft diameter preoperatively. LEVEL OF EVIDENCE: Diagnostic study; Level II.

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect.

PURPOSE: The aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL-reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL-reconstructed knee. METHODS: Twelve fresh-frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.0 N anterior tibial load; (b) 4.0 N m internal and external rotational torques. Anatomic single-bundle ACL reconstruction with a 7 mm-diameter bovine extensor tendon graft was performed. A massive, middle segment, lateral meniscus defect was created via arthroscopy, and arthroscopic centralization was performed with a 1.4 mm anchor with a #2 suture. The LM states with ACL reconstruction evaluated were: intact, massive middle segment defect and with the lateral meniscus centralization procedure. RESULTS: The rotation of the ACL reconstructed knee with the lateral meniscus defect was significantly higher than with the centralized lateral meniscus under an external rotational torque at 30° of knee flexion, and under an internal rotational torque at 30° and 45° of knee flexion. There were no systematic and consistent effects of LM centralization under anterior tibial translation. CONCLUSIONS: In this porcine model, the capsular support of middle segment of the lateral meniscus using arthroscopic centralization improved the residual rotational laxity of the ACL-reconstructed knee accompanied with lateral meniscus dysfunction due to massive meniscus defect. This study quantifies the benefit to knee kinematics of arthroscopic centralization by restoring the lateral meniscal function.

Comparison of three approaches for femoral tunnel during double-bundle anterior cruciate ligament reconstruction: A case controlled study.

BACKGROUND: It is still controversial whether which femoral tunnel creation technique is best during anterior cruciate ligament reconstruction (ACLR). We aimed to clarify the features of three different techniques based on the femoral tunnel position created with the same tunnel-creating concept and the measurement data. METHODS: The femoral tunnel of double-bundle (DB) ACLR was created using the behind-remnant approach in a remnant preserved manner following the policy of our institute. The trans-tibial approach (TT) was applied for all primary ACL injured cases until December 2012. The trans-portal approach (TP) was applied from January to September 2013, and the outside-in approach (OI) was indicated from October 2013 to March 2014. We compared the femoral tunnel aperture positions with the postoperative three-dimensional computed tomography (3D-CT). Additionally, the femoral tunnel length and the septum distance of each anteromedial (AM) and posterolateral (PL) tunnel were analyzed. RESULTS: The AM tunnel aperture position of TT was significantly higher and shallower than that of TP in knee flexion position. The femoral tunnel length of TP was significantly shorter than that of TT and OI. The septum between each tunnel of OI trended wider than that of TT and TP. CONCLUSIONS: The AM tunnel aperture position of TT runs the risk of a high and shallow position. TP runs the risk of insufficiently short tunnel length. It is important to apply each method flexibly to each case because no single best approach was found.

Prediction of Venous Thromboembolism after Total Knee Arthroplasty Using Dielectric Blood Coagulometry.

BACKGROUND: Venous thromboembolism (VTE) including deep vein thrombosis (DVT) and pulmonary embolism (PE) frequently occurs in patients undergoing total knee arthroplasty (TKA). This study aimed to evaluate the efficacy of dielectric blood coagulometry (DBCM) as a new technique for predicting postoperative VTE. METHODS: Thirty patients undergoing TKA were enrolled. DVT was diagnosed by ultrasonography preoperatively and on the fourth or fifth postoperative day. Enhanced computed tomography was performed to detect PE on the fourth postoperative day. The day after surgery, a blood sample was measured by DBCM. All patients received fondaparinux or low-molecular-weight heparin for postoperative thromboprophylaxis. RESULTS: Eighteen of the 30 patients had DVT postoperatively, and 10 had asymptomatic PE. Seven patients had both DVT and PE. The patterns of permittivity as a function of time and frequency from the DBCM measurement were different between patients with and without VTE. The sensitivity and specificity of the parameter constructed from a set of permittivities at the frequencies of 2.5 kHz, 1 MHz, and 10 MHz were 90% and 78%, respectively. CONCLUSIONS: DBCM was effective and efficient for predicting VTE after TKA.

Attachment area of fibres from the horns of lateral meniscus: anatomic study with special reference to the positional relationship of anterior cruciate ligament.

PURPOSE: Although studies support the clinical importance of the fibres from the horns of lateral meniscus (LM), few studies have investigated the detailed anatomy. This anatomic study was conducted to analyse the structural details of LM with special reference to (1) the attachment area of the fibres from the anterior and posterior horns and (2) the positional relationship between these fibres and the anterior cruciate ligament (ACL). METHODS: A total of 24 cadaveric knees were used in the macroscopic investigation, and six knees were used in the histological investigation. Micro-computed tomography analysis was also performed to assess the anatomy of the posteriormost fibre from the posterior horn of LM. RESULTS: Based on the macroscopic investigations, the outer fibres from the anterior horn of LM extended to ACL and seemed to intermingle with ACL fibres. However, the histological investigations showed a distinct border between the fibres and ACL. The inner fibres from the anterior horn of LM attached to the lateral intercondylar tubercle serving as a lateral margin of ACL attachment. Fibres from the posterior horn of LM were separated into anterolateral and posteromedial crura which attached to the posterior aspect of the lateral and medial intercondylar tubercles, respectively. These two crura formed the posterior margin of the ACL attachment, except for the central part of ACL. CONCLUSION: The outer fibres from the anterior horn of LM adjoined ACL. The inner fibres from the anterior horn of LM and two crura from the posterior horn of LM formed the border of the attachment area of ACL. The distinctive fibre anatomy from LM could provide a surgical landmark during arthroscopic surgery.

Evaluation of pivot shift phenomenon while awake and under anaesthesia by different manoeuvres using triaxial accelerometer.

PURPOSE: Evaluating pivot shift phenomenon is difficult due to its subjectivity, wide variation of testing manoeuvres, and difficulty in evaluating patients while awake. The purpose of this study was to evaluate the pivot shift phenomenon using a triaxial accelerometer by two different manoeuvres, the pivot shift test as representative of flexion manoeuvre and N test as a representative of extension manoeuvre, and in two different conditions, awake and under anaesthesia. METHODS: Twenty-nine patients with unilateral anterior cruciate ligament (ACL)-injured knee were included. Pivot shift test and N test were performed for both injured and uninjured legs while awake and under anaesthesia, with the acceleration measurements using a triaxial accelerometer (KiRA). The tests were also subjectively graded on a scale of 0-6 based on the modification of IKDC criteria. RESULTS: Under anaesthesia, acceleration of ACL-injured knees was greater than that of uninjured knees in both pivot shift test (P < 0.001) and N test (P < 0.001) , whereas the acceleration value was greater in the N test. Furthermore, there were significant positive correlations between the acceleration and subjective grading in both tests, whereas the N test was more significant than the pivot shift test. On the other hand, there was no statistical significance in acceleration between ACL-injured and uninjured knees in either test while the patient was awake. CONCLUSION: The triaxial accelerometer was useful to objectively detect and quantitatively evaluate the pivot shift phenomenon by both the pivot shift test and N test under anaesthesia. The acceleration of ACL-injured knees was greater than that of uninjured knees, and the acceleration was correlated with the subjective manual grading, especially in the N test. On the other hand, its use while the patient was awake was likely limited. LEVELS OF EVIDENCE: Diagnostic study of non-consecutive patients without a universally applied gold standard, Level III.

The Effect of Teeth Clenching on Dynamic Balance at Jump-Landing: A Pilot Study.

The aim of this study was to analyze the effect of teeth clenching on dynamic balance at jump landing. Twenty-five healthy subjects performed jump-landing tasks with or without teeth clenching. The first 3 trials were performed with no instruction; subsequently, subjects were ordered to clench at the time of landing in the following 3 trials. We collected the data of masseter muscle activity by electromyogram, the maximum vertical ground reaction force (vGRFmax) and center of pressure (CoP) parameters by force plate during jump-landing. According to the clenching status of control jump-landing, all participants were categorized into a spontaneous clenching group and no clenching group, and the CoP data were compared. The masseter muscle activity was correlated with vGRFmax during anterior jump-landing, while it was not correlated with CoP. In comparisons between the spontaneous clenching and the no clenching group during anterior jump-landing, the spontaneous clenching group showed harder landing and the CoP area became larger than the no clenching group. There were no significant differences between pre- and postintervention in both spontaneous clenching and no clenching groups. The effect of teeth clenching on dynamic balance during jump-landing was limited.

Two-Year Outcomes After Arthroscopic Lateral Meniscus Centralization.

PURPOSE: To evaluate clinical and radiographic outcomes of arthroscopic centralization for lateral meniscal extrusion. METHODS: Twenty-one patients who underwent arthroscopic centralization of the lateral meniscus were included. In cases with an extruded lateral meniscus (9 patients) or discoid meniscus (12 patients), the capsule at the margin between the midbody of the lateral meniscus and the capsule was sutured to the lateral edge of the lateral tibial plateau and centralized using suture anchors to reduce or prevent meniscal extrusion. Clinical outcomes included clinical examination findings, Lysholm score, Knee Injury and Osteoarthritis Outcome Score, and subjective rating scales regarding patient satisfaction and sports performance level. Radiographic outcomes included meniscal extrusion width (MEW) on magnetic resonance imaging and lateral joint space width on a standing 45° flexion posteroanterior view. All clinical and radiographic outcomes were reported pre-operatively and at 2 years post-operatively, whereas MEW was reported at 1 year; outcomes were compared with baseline. RESULTS: Clinical outcomes were significantly improved at 2 years postoperatively compared with baseline: Lysholm score (97 v 69, P < .0001) and all subscores of the Knee Injury and Osteoarthritis Outcome Score except activities of daily living (pain, 89 v 72, P = .0010; symptoms, 91 v 74, P = .0002; activities of daily living, 94 v 89, P = .091; sport and recreational function, 79 v 42, P = .0028; and quality of life, 78 v 46, P = .0029). Patient satisfaction (84 v 22, P < .0001) and sports performance level (82 v 15, P < .0001) were also improved. At 1 year, MEW was significantly reduced compared with baseline for both the extrusion group (1.0 mm v 5.0 mm, P < .0001) and the discoid group (0.3 mm v 1.6 mm, P = .047). Lateral joint space width increased at 2 years in the extrusion group (5.6 mm v 4.8 mm, P = .041) and was maintained in the discoid group (5.5 mm v 5.4 mm). CONCLUSIONS: Arthroscopic centralization of the lateral meniscus improved clinical and radiographic outcomes for meniscal extrusion as well as for discoid menisci at 2-year follow-up. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Dynamic Evaluation of Pivot-Shift Phenomenon in Double-Bundle Anterior Cruciate Ligament Reconstruction Using Triaxial Accelerometer.

PURPOSE: To evaluate the effect of initial graft tension on rotational stability and to determine the minimum required tension (MRT) based on the pivot-shift phenomenon in isolated anteromedial bundle (AMB), isolated posteromedial bundle (PLB), and double-bundle anterior cruciate ligament (ACL) reconstructions using a triaxial accelerometer during surgery. METHODS: Primary double-bundle ACL reconstructions were included. The pivot-shift test and N-test were performed before and during surgery with the acceleration measurements using a triaxial accelerometer. The pivot-shift test was also manually graded. The AMB and PLB were fixed to a graft tensioning system during surgery with the following settings: (1) AMB only (AMB), (2) PLB only (PLB), and (3) AMB and PLB (A+P). The total graft tension was first set at 20 N and then was increased in increments of 10 N until the pivot-shift test became negative, which was defined as the MRT in each setting. RESULTS: Twenty-five patients were evaluated. The MRT in the AMB setting averaged 26 N (range, 20 to 40 N); in the PLB setting, 28 N (range, 20 to 40 N); and in the A+P setting, 24 N (range, 20 to 40 N). The MRT in the A+P setting was significantly smaller than that in the PLB setting (P = .008). The acceleration in the A+P setting was significantly smaller than that in the AMB and PLB settings both in the pivot-shift test (vs AMB: P = .007, vs PLB: P = .011) and in the N-test (vs AMB: P < .001, vs PLB: P < .001). CONCLUSIONS: Double-bundle ACL reconstruction better controlled rotational stability with smaller MRT than isolated PLB reconstruction at the time of surgery. In double-bundle reconstruction, the MRT based on the pivot-shift phenomenon could be larger than previously reported MRT based on anteroposterior laxity. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Behind-remnant arthroscopic observation and scoring of femoral attachment of injured anterior cruciate ligament.

PURPOSE: To describe the femoral anterior cruciate ligament (ACL) attachment based on the behind-remnant observation with a new scoring system and to investigate the characteristics of an ACL injured knee. METHODS: One hundred and twenty-six ACL injured knees with four standardized arthroscopic photos and full evaluation under anaesthesia were included in the study. Sixty non-ACL injured knees were also evaluated as control. A scoring system for the femoral ACL attachment was set as follows based on behind-remnant findings; the direct insertion was divided into three portions as proximal, middle and distal. The fibrous extension from the articular surface (indirect insertion) and the severity of synovitis were also graded into 2, 1 and 0 points. The total score was 10 as full marks. The correlation between each score and total score, as well as age at surgery, gender, anterior laxity, pivot-shift test and meniscus injuries, was statistically evaluated with a significance of 0.05. RESULTS: The femoral attachment score of the ACL injured knees was statistically different from that of the non-ACL injured knees. Anterior laxity was dependent only on the integrity of the proximal portion. Knee instability was significantly correlated with the status of the direct insertion. Medial and lateral meniscus injuries were correlated with the middle part and the distal part of the direct insertion, respectively. The direct insertion was less preserved in distal and articular sides. CONCLUSION: Arthroscopic observation behind the remnant of the injured ACL showed clearer findings of the femoral attachment than that from the front. Behind-remnant observation greatly assists in the creation of a correct anatomical tunnel with the preserving remnant. The scoring system indicated several significant correlations between the score and preoperative patient status.

In-vivo kinematics of high-flex posterior-stabilized total knee prosthesis designed for Asian populations.

PURPOSE: The purpose of this study was to determine in-vivo kinematics of our developed posterior-stabilized (PS) total knee prosthesis for Asian populations in comparison with a popular high-flexion PS prosthesis. METHODS: We analyzed 62 osteoarthritic knees: 31 knees with the new PS prosthesis (group A) and 31 knees with a popular high-flexion PS prosthesis (group B). Radiographic knee images were taken during standing, lunge, and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-based shape matching techniques. RESULTS: Group A showed slightly greater implant flexion angles compared with knees with conventional prosthesis at maximum lunge (average: 119 vs. 110°, p = 0.001), and at maximum kneeling (121 vs. 114°, p = 0.004), although the range of motion was not significantly different. The femoral centre positions were more posterior in group A at standing, at 90° lunge, at maximum lunge (-9 and -7 mm, p = 0.004), at 90° kneeling, and at maximum kneeling (-9 vs. -7 mm, p = 0.016), and posterior translations of the femoral center were greater at 90° knee flexion postures. The femoral centre positions had a strong negative correlation with implant flexion angles at maximum lunge in group B (r = -0.893, p < 0.001), but not in group A (p = 0.242). CONCLUSIONS: The new PS prosthesis designed for Asian knee morphology achieved flexion angles and range of motion at least comparable to that of conventional high-flexion PS prosthesis. The femoral roll-back pattern, however, is different from a conventional knee, reflecting the post/cam design.

Effect of short-term fatigue, induced by high-intensity exercise, on the profile of the ground reaction force during single-leg anterior drop-jumps.

[Purpose] Fatigue may be an important contributing factor to non-contact anterior cruciate ligament injuries in sports. The purpose of this study was to evaluate the effects of controlled lower limb fatigue, induced by a short-term, high-intensity exercise protocol, on the profile of the ground reaction force during landings from single-leg anterior drop-jumps. [Subjects and Methods] Twelve healthy males, 18 to 24 years old, performed single-leg anterior drop-jumps, from a 20 cm height, under two conditions, 'fatigue' and 'non-fatigue'. Short-term fatigue was induced by high-intensity interval cycling on an ergometer. Effects of fatigue on peak vertical ground reaction force, time-to-peak of the vertical ground reaction force, and loading rate were evaluated by paired t-test. [Results] Fatigue shortened the time-to-peak duration of the vertical ground reaction force by 10% (non-fatigue, 44.0 ± 16.8 ms; fatigue, 39.6 ± 15.8 ms). Fatigue also yielded a 3.6% lowering in peak vertical ground reaction force and 9.4% increase in loading rate, although these effects were not significant. [Conclusion] The effects of fatigue in reducing time-to-peak of the vertical ground reaction force during single-leg anterior drop-jumps may increase the risk for non-contact anterior cruciate ligament injury in males.

Mid- to long-term results of single-bundle versus double-bundle anterior cruciate ligament reconstruction: randomized controlled trial.

PURPOSE: To evaluate the mid-to long-term results of a randomized controlled trial of single-bundle (SB) versus double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using a semitendinosus tendon. METHODS: Seventy-eight patients who underwent primary ACL reconstruction with an autologous semitendinosus tendon were prospectively randomized into 2 groups: SB reconstruction (n = 39) and DB reconstruction (n = 39). In both groups, grafts were fixed at 30° of flexion with a total tension of 80 N. The following evaluation methods were used: clinical examination, KT-1000 arthrometer (MEDmetric, San Diego, CA) measurement, muscle strength, Tegner activity score, Lysholm score, subjective rating scale regarding patient satisfaction and sports performance level, graft retear, contralateral ACL tear, and additional meniscus surgery. RESULTS: Fifty-three patients (25 in SB group and 28 in DB group) who were followed up for a minimum of 3 years (mean, 69 months; range, 36 to 140 months) were evaluated. Preoperatively, there were no differences between the groups. Postoperatively, the Lachman and pivot-shift test results were better in the DB group (P = .024 and P < .0001, respectively). KT measurements were better in the DB group (mean, 1.4 mm v 2.7 mm; P = .0023). The Tegner score was also better in the DB group (P = .033). There were no significant differences in range of motion, muscle strength, Lysholm score, subjective rating scale, graft retear, and secondary meniscal tear. CONCLUSIONS: In ACL reconstruction using the transtibial approach, DB reconstruction was significantly better than SB reconstruction regarding anterior and rotational stability during the 3- to 12-year follow-up. The results of KT measurements and the Lachman and pivot-shift tests were significantly better in the DB group, whereas there was no difference in the anterior drawer test results. The Tegner score was also better in the DB group; however, there were no differences in the other subjective findings. LEVEL OF EVIDENCE: Level II, lesser-quality prospective randomized trial.