Kouki Nagamune

Double-bundle ACL reconstruction can improve rotational stability.

Double-bundle anterior cruciate ligament (ACL) reconstruction reproduces anteromedial and posterolateral bundles, and thus has theoretical advantages over conventional single-bundle reconstruction in controlling rotational torque in vitro. However, its superiority in clinical practice has not been proven. We analyzed rotational stability with three reconstruction techniques in 60 consecutive patients who were randomly divided into three groups (double-bundle, anteromedial single-bundle, posterolateral single-bundle). In the reconstructive procedure, the hamstring tendon was harvested and used as a free tendon graft. Followup examinations were performed 1 year after surgery. Anteroposterior laxity of the knee was examined with a KT-1000 arthrometer, whereas rotatory instability, as elicited by the pivot shift test, was assessed using a new measurement system incorporating three-dimensional electromagnetic sensors. Routine clinical evaluations, including KT examination, demonstrated no differences among the three groups. However, using the new measurement system, patients with double-bundle ACL reconstruction showed better pivot shift control of complex instability than patients with anteromedial and posterolateral single-bundle reconstruction.Level of Evidence: Level II, therapeutic study. See the Guideline for Authors for a complete description of levels of evidence.

In Vivo Measurement of the Pivot-Shift Test in the Anterior Cruciate Ligament–Deficient Knee Using an Electromagnetic Device

Background The pivot-shift test is commonly used for assessing dynamic instability in anterior cruciate ligament—insufficient knees, which is related to subjective knee function, unlike static load-displacement measurement. Conventional measurements of 3-dimensional position displacement cannot assess such dynamic instability in vivo and produce comparable parameters. Not only 3-dimensional position displacement but also its 3-dimensional acceleration should be measured for quantitative evaluation of the pivot-shift test. Hypothesis Knees with a positive pivot-shift test result have increased tibial anterior translation and acceleration of its subsequent posterior translation, and they are correlated with clinical grading. Study Design Controlled laboratory study. Materials and Methods Thirty patients with isolated anterior cruciate ligament injury were included. Pivot-shift tests were evaluated under anesthesia manually and experimentally using an electromagnetic knee 6 degrees of freedom measurement system. From 60 Hz of 6 degrees of freedom data, coupled tibial anterior translation was calculated, and acceleration of posterior translation was computed by secondary derivative. Results All anterior cruciate ligament—deficient knees demonstrated a positive pivot-shift test result. The coupled tibial anterior translation was 7.7 and 15.6 mm in anterior cruciate ligament—intact and —deficient knees, respectively. The acceleration of posterior translation was —797 and —2001 mm/s 2, respectively. These differences were significant (P < .01). The coupled tibial anterior translation and acceleration of posterior translation in the anterior cruciate ligament—deficient knee were larger in correlation with clinical grading (P = .03 and P < .01, respectively). Conclusion The increase of tibial anterior translation and acceleration of subsequent posterior translation could be detected in knees with a positive pivot-shift result, and this increase was correlated to clinical grading. Clinical Relevance These measurements can be used for quantified evaluation of dynamic instability demonstrated by the pivot-shift test.

The effect of platelet-rich plasma on the regenerative therapy of muscle derived stem cells for articular cartilage repair

OBJECTIVE Platelet-rich plasma (PRP) is reported to promote collagen synthesis and cell proliferation as well as enhance cartilage repair. Our previous study revealed that the intracapsular injection of muscle derived stem cells (MDSCs) expressing bone morphogenetic protein 4 (BMP-4) combined with soluble Flt-1 (sFlt1) was effective for repairing articular cartilage (AC) after osteoarthritis (OA) induction. The current study was undertaken to investigate whether PRP could further enhance the therapeutic effect of MDSC therapy for the OA treatment. METHODS MDSCs expressing BMP-4 and sFlt1 were mixed with PRP and injected into the knees of immunodeficient rats with chemically induced OA. Histological assessments were performed 4 and 12 weeks after cell transplantation. Moreover, to elucidate the repair mechanisms, we performed in vitro assays to assess cell proliferation, adhesion, migration and mixed pellet co-culture of MDSCs and OA chondrocytes. RESULTS The addition of PRP to MDSCs expressing BMP-4 and sFlt1 significantly improved AC repair histologically at week 4 compared to MDSCs expressing BMP-4 and sFlt1 alone. Higher numbers of cells producing type II collagen and lower levels of chondrocyte apoptosis were observed by MDSCs expressing BMP-4 and sFlt1 and mixed with PRP. In the in vitro experiments, the addition of PRP promoted proliferation, adhesion and migration of the MDSCs. During chondrogenic pellet culture, PRP tended to increase the number of type II collagen producing cells and in contrast to the in vivo data, it increased cell apoptosis. CONCLUSIONS Our findings indicate that PRP can promote the therapeutic potential of MDSCs expressing BMP-4 and sFlt1 for AC repair (4 weeks post-treatment) by promoting collagen synthesis, suppressing chondrocyte apoptosis and finally by enhancing the integration of the transplanted cells in the repair process.

Similarities and Differences of Diagnostic Manual Tests for Anterior Cruciate Ligament Insufficiency: A Global Survey and Kinematics Assessment

Background: The Lachman and pivot-shift tests are 2 standard manual tests to diagnose anterior cruciate ligament (ACL) insufficiency. However, the global variation of these testing procedures is not known. Purpose: To survey currently used testing techniques and to measure the knee movement during manual tests among various expert surgeons from across the globe. Study Design: Controlled laboratory study. Methods: Part 1: descriptive survey. A questionnaire asking about testing procedures of Lachman and pivot-shift tests was conducted among 33 ACL surgeons. Part 2: knee kinematics comparison. Lachman and pivot-shift tests were performed on a unilateral ACL-injured patient by 5 surgeons, while knee kinematics was recorded by an electromagnetic system. Tibial translation was measured during the Lachman test, while tibial translation, rotation, and pivot-shift acceleration were calculated during the pivot-shift test. Results: Part 1: Tibial anterior drawer by a medially placed hand was widely advocated for the Lachman test. Flexion type of the pivot-shift test maneuver was supported by two thirds, while extension type was supported by one third. However, the “feeling” of subluxation or reduction during the pivot shift was the primary evaluation method used by the vast majority of surgeons. Part 2: Increased tibial translation during the Lachman test was observed in the ACL-injured knee with significant variation between examiners (P < .01). Tibial translation and pivot-shift acceleration during the pivot-shift test increased in the ACL-injured side (P < .01), but tibial rotation was too diverse to find any trend (P = .31). Tibial translation and acceleration of the pivot shift in the ACL-injured knee showed no significant difference between examiners (P > .05). Conclusion: The Lachman test can display a wide variation of actual movement despite maneuver similarity, while the pivot-shift test could possibly be measurable by tibial translation and/or acceleration beyond their procedural variation. Clinical Relevance: We should recognize the limitations of these manual tests and the possibilities of their objective measurement.

Quantitative measurement of the pivot shift, reliability, and clinical applications

Static load–displacement measurement is unrelated to the dynamic knee function of anterior cruciate ligament (ACL) insufficiency. Performing an accurate, dynamic functional evaluation is necessary not only for the primary ACL injury, but also as an outcome measurement in ACL reconstruction. The pivot shift test is commonly used for assessing dynamic rotatory knee laxity in ACL-insufficient knees and is related to subjective knee function. Residual pivot shift after ACL reconstruction is a crucial factor related to poor clinical outcome. However, the pivot shift test is subjectively determined by the examiners’ hands. Not only 3-dimensional (3D) position displacement but also its 3D acceleration should be measured for quantitative evaluation of the pivot shift test and is currently feasible by using recent advanced technology, i.e., electromagnetic devices. We summarize the basic knowledge and current concepts of quantitative exploration of the dynamic knee movement during the pivot shift test.

Three-Dimensional Analysis of Bone Tunnel Changes After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using Multidetector-Row Computed Tomography

Background: The femoral and tibial bone tunnel enlargement after anatomic double-bundle anterior cruciate ligament reconstruction (ACL-R) has not been fully documented. Purpose: To evaluate the region-specific bone tunnel volume changes and those transpositions using 3-dimensional multidetector-row computed tomography (MDCT) after anatomic double-bundle ACL-R. Study design: Case series; Level of evidence, 4. Methods: Eleven patients who underwent unilateral double-bundle ACL-R with hamstring tendon autografts were included in this study. MDCT scanning of their knees was performed at 3 weeks and 1 year after surgery. The bone tunnel regions were extracted from the MDCT images, and the longitudinal axis of each bone tunnel was divided into 3 equal sections. The centroids of the outside and the articular thirds were then extracted from the bone tunnel position. Changes in the bone tunnel volume and the transposition of the articular third were calculated and compared. Results: At 1 year postoperatively, as compared with the 3-week postoperative value (set at 100%), the femoral bone tunnel volume of the anteromedial bundle (AMB) and posterolateral bundle (PLB) changed to 77.4% ± 15.3% and 102.3% ± 19.2% in the outside third and 122.3% ± 31.8% and 112.5% ± 34.4% in the articular third, respectively. The tibial bone tunnel volume of the AMB and the PLB changed to 108.6% ± 28.7% and 105.4% ± 22.6% in the tibial articular third and 54.9% ± 25.8% and 52.5% ± 26.9% in the outside third, respectively. The femoral outside third of the AMB and the tibial outside third of both the AMB and PLB were significantly reduced in bone tunnel volume. The centroid of the femoral articular third of the AMB moved 13°, 1.1 ± 0.6 mm posterodistally, and that of the PLB moved 35°, 0.8 ± 0.4 mm anterodistally. Furthermore, the centroid of the tibial articular third of the AMB moved 14°, 2.0 ± 1.6 mm posterolaterally, and that of the PLB moved 72°, 1.0 ± 1.3 mm posterolaterally. Conclusion: Compared with 3 weeks postoperatively, the articular side outlets of the femoral and tibial bone tunnels at 1 year postoperatively had enlarged slightly but statistically maintained their volume, and they had moved a little in the direction that the grafts were pulled.

Biomechanical analysis of the knee with partial anterior cruciate ligament disruption: quantitative evaluation using an electromagnetic measurement system.

PURPOSE To investigate the biomechanical function of anterior cruciate ligament (ACL) remnants in ACL-deficient knees with both partial and complete tears. METHODS Twenty partial ACL-deficient (group P), 20 complete ACL-deficient (group C), and 40 contralateral ACL-intact knees were examined. The end point during the Lachman test, side-to-side differences of KT-1000 measurements, and the pivot shift test were evaluated. Additionally, the side-to-side difference of anterior tibial translation during the Lachman test and the acceleration during the pivot shift test were calculated using an electromagnetic measurement system (EMS). RESULTS The end point was found in 9 patients in group P, whereas it was not detected in group C. In KT-1000 measurements, the mean side-to-side differences were 3.8 ± 2.4 mm in group P and 5.4 ± 2.3 mm in group C. There was a significant difference between these 2 groups (P < .05). In the pivot shift test evaluation in group P, one patient was evaluated as grade 0, 17 patients as grade 1+, and 2 patients as grade 2+. In group C, 10 patients were evaluated as grade 1+, 9 patients as grade 2+, and one patient as grade 3+. Using the EMS, mean side-to-side differences during the Lachman test were 3.1 ± 2.1 mm in group P and 7.2 ± 3.2 mm in group C. The anterior-posterior displacement in group P was significantly less than that in group C (P < .05). In the quantitative pivot shift test, the mean acceleration in the contralateral ACL-intact knees was -632.7 ± 254.5 mm/s(2), whereas it was -1107.5 ± 398.9 mm/s(2) in group P and -1652.2 ± 754.9 mm/s(2) in group C. Significant differences were detected between the 3 knee conditions (P < .05). CONCLUSIONS The quantitative assessments of knees with partial ACL ruptures during the Lachman test and the pivot shift test using the EMS showed less laxity than did knees with complete ACL tears, whereas their laxity was greater than the contralateral knees with intact ACLs. LEVEL OF EVIDENCE Level III, diagnostic study of nonconsecutive patients.

The Use of an Electromagnetic Measurement System for Anterior Tibial Displacement During the Lachman Test

PURPOSE The purpose of this study was to assess quantitative anterior/posterior values during the Lachman test by an electromagnetic measurement system and to compare data with KT-1000 arthrometric measurements (MEDmetric, San Diego, CA), as well as the measurement of radiologic laxity by dynamic radiographs. METHODS We used an electromagnetic device to quantitatively evaluate anterior knee displacements. We tested 82 knees in 41 patients (30 isolated anterior cruciate ligament [ACL]-deficient, 11 ACL-reconstructed, and 41 contralateral ACL-intact knees). Anterior displacements during the Lachman test were calculated by the electromagnetic measurement system and fluoroscopic measurement, and anterior displacements were also measured by the KT-1000 arthrometer. Anterior/posterior displacements measured by these methods were compared, and correlations were assessed. RESULTS In ACL-deficient knees, mean anterior/posterior displacement (±SE) was 22.4 ± 0.8 mm in electromagnetic measurements, 22.0 ± 0.7 mm in fluoroscopic measurements, and 15.0 ± 0.6 mm in KT-1000 measurements. In contralateral ACL-intact knees, it was 15.7 ± 0.6 mm, 15.6 ± 0.5 mm, and 9.9 ± 0.4 mm, respectively. In ACL-reconstructed knees, it was 15.7 ± 0.7 mm, 16.2 ± 0.8 mm, and 11.2 ± 0.6 mm, respectively. In all knee conditions, significant differences between fluoroscopic measurements and KT-1000 measurements were detected (P < .01). Significant differences were also detected between electromagnetic measurements and KT-1000 measurements (P < .01). No significant differences were detected between fluoroscopic measurements and electromagnetic measurements. A strong correlation was obtained between KT-1000 measurements and fluoroscopic measurements (r = 0.62, P < .01) and between electromagnetic measurements and KT-1000 measurements (r = 0.64, P < .01). However, the strongest correlation was observed between electromagnetic measurements and fluoroscopic measurements (r = 0.96, P < .01). CONCLUSIONS An electromagnetic measurement system to test anterior/posterior tibial translation determined that quantification of the Lachman test could be performed as accurately as fluoroscopic measurements. LEVEL OF EVIDENCE Level II, development of diagnostic criteria on basis of consecutive patients with universally applied reference gold standard.

Validation of Quantitative Measures of Rotatory Knee Laxity.

Background: Prior attempts to quantify the pivot-shift examination have been too invasive or impractical for clinical use. A noninvasive method for quantifying rotatory knee laxity is needed. Hypothesis: Greater quantitative measurements of rotatory knee laxity (both of the involved knee as well as compared with the contralateral healthy knee) are associated with an increasing clinical pivot-shift grade. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 103 patients undergoing anatomic single-bundle anterior cruciate ligament (ACL) reconstruction at 4 international centers underwent a standardized pivot-shift test preoperatively on both knees while anesthetized. Clinical grading of the pivot shift was performed according to the International Knee Documentation Committee (IKDC) knee ligament rating system. Two different quantitative technologies were used to measure rotatory knee laxity: an inertial sensor and an image analysis were independently used to measure tibial acceleration and lateral compartment translation, respectively, during the pivot-shift test. Patients were dichotomized to “high-grade” (abnormal and severely abnormal) or “low-grade” (normal and nearly normal) rotatory knee laxity groups based on the clinical pivot-shift test result of the involved side. Tibial acceleration and lateral compartment translation of the involved knee and the side-to-side difference between the involved and contralateral knees were separately compared between the high- and low-grade rotatory knee laxity groups utilizing t tests; significance was set at P < .05. Results: Forty-three patients were in the low-grade rotatory knee laxity group, and 60 patients were in the high-grade rotatory knee laxity group. Patients in the high-grade knee laxity group had significantly higher lateral compartment translation as measured with the image analysis (involved knee: 3.8 ± 2.3 mm; side-to-side difference: 2.5 ± 2.4 mm) compared with patients in the low-grade group (involved knee: 2.0 ± 1.4 mm; side-to-side difference: 1.4 ± 1.5 mm) (both P < .01). As measured with the inertial sensor, tibial acceleration for patients in the high-grade group was significantly higher (involved knee: 7.2 ± 5.3 m/s2; side-to-side difference: 4.2 ± 5.4 m/s2) compared with patients in the low-grade group (involved knee: 4.2 ± 1.6 m/s2; side-to-side difference: 1.2 ± 1.2 m/s2) (both P < .01). Conclusion: The inertial sensor and image analysis techniques were able to detect differences between low- and high-grade pivot-shift test results. A quantitative assessment of the pivot-shift test could augment the diagnosis of an ACL injury and improve the ability to detect changes in rotatory knee laxity over time.

Unconstrained evaluation system for heart rate using ultrasonic vibrograph

Unconstrained health monitoring systems have received much considerable attention in medical applications, because such system can examine a subject without constraint. In this study, we propose a detection method based on a fuzzy logic for evaluating heart rate using our ultrasonic vibrograph. In the experiment for confirming heart rate, our method has been successfully used to detect the heart rates of four subjects, compared with a method using an electrocardiograph.