Yuichiro Nishizawa

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.

Differences in Knee Kinematics Between Awake and Anesthetized Patients During the Lachman and Pivot-Shift Tests for Anterior Cruciate Ligament Deficiency

Background: The Lachman and pivot-shift tests have been widely used for detecting anterior cruciate ligament (ACL) deficiency. However, it still remains unclear whether these manual tests can be quantified accurately while patients are awake. Purpose: To assess the differences in knee kinematics of awake and anesthetized patients. Study Design: Case series; Level of evidence, 4. Methods: A total of 50 patients with unilateral ACL rupture were examined. Anteroposterior tibial translation was assessed using a KT-1000 arthrometer at maximal manual power. Anterior tibial translations during the manual Lachman test and the acceleration of tibial posterior translation (APT) during the pivot-shift test were also measured using an electromagnetic measurement system (EMS). All 3 measurements were performed on the day previous to surgery while the patients were awake and on the operative day before the surgery while the patients were under general anesthesia. Results: The mean side-to-side difference in anteroposterior tibial translation was 5.6 ± 2.6 mm in the awake state and 5.9 ± 3.5 mm under anesthesia, indicating a nonsignificant difference. According to the EMS, the mean side-to-side difference in anteroposterior tibial translation during the Lachman test was 4.6 ± 3.6 mm in the awake state and 6.9 ± 4.3 mm under anesthesia, indicating a significant difference (P < .01). The mean APT during the pivot-shift test was −0.8 ± 0.3 m/s2 in intact knees and −1.1 ± 0.4 m/s2 in ACL-deficient knees when the patients were awake and was −0.7 ± 0.2 m/s2 and −1.7 ± 1.0 m/s2, respectively, when the patients were under anesthesia. In ACL-deficient knees, the APT pivot-shift test result was significantly higher when the patients were under anesthesia than when they were awake (P < .01). Conclusion: In ACL-deficient knees, the knee kinematics during the Lachman and pivot-shift tests is significantly affected by patient consciousness, and caution is needed in quantifying anterior knee laxity during these tests when the patients are awake.

Matching Articular Surfaces of Selected Donor and Recipient Sites for Cylindrical Osteochondral Grafts of the Femur

Background: Autogenous osteochondral grafting has been widely performed as a treatment for focal osteochondral defects. In this procedure, it is important to match the shape of the articular surface between the donor site and recipient site to reproduce the original articular surface of the femur. Purpose: To investigate the ideal matching patterns of articular surface profiles of donor and recipient sites for autogenous osteochondral grafting of the femur using a 3-dimensional laser scanning method. Study Design: Descriptive laboratory study. Methods: The donor and recipient sites in 11 cadaveric knees were examined, and each of the sites was divided into 12 areas. In the donor sites, the contours of the articular surface of the medial and lateral femoral trochleae were determined. In the recipient sites, the contours of the articular surface of the medial and lateral femoral condyles were assessed. Vertical intervals (VIs) were then calculated as the parameter for the height of the articular surface. The VI was the height difference from the highest and lowest points in the contours of the articular surface within the area of the donor and recipient sites. Finally, assessments were made on whether the articular surface of the donor and recipient sites matched properly for cylindrical osteochondral grafts with diameters of 6, 8, and 10 mm. Results: For the donor site, the VIs of the middle area of the femoral trochlea were significantly smaller than those of the peripheral area. For the recipient site, the VIs of the anterior area of the femoral condyle were significantly smaller than those of the posterior area. Conclusion: These results indicated in aging specimens that the articular surface profile of the middle area of the donor site matched that of the anterior area of the recipient site. On the other hand, the shape of the articular surface of the peripheral area of the donor site was congruent with that of the posterior area of the recipient site. Clinical Relevance: This study will be useful for improving donor site selection during preoperative planning. The authors recommend selection of the middle area of the femoral trochlea for cartilage defects in the anterior area of the femoral condyle and of the peripheral area of the femoral trochlea for cartilage defects in the posterior area of the femoral condyle.

The influence of patella height on soft tissue balance in cruciate-retaining and posterior-stabilised total knee arthroplasty

PurposeAlthough the patella reduced or everted position has recently been recognised as an important factor influencing soft tissue balance during assessment in total knee arthroplasty (TKA), the influence of patella height on soft tissue balance has not been well addressed. Therefore, the relationship between soft tissue balance and patella height was investigated and differences between cruciate-retaining (CR) and posterior-stabilised (PS) TKA were compared.MethodsForty consecutive patients blinded to the type of implant received, were randomised prospectively. Using lateral radiographs, pre-operative patella height was measured. Using an offset-type tensor designed to measure the soft tissue balance with a reduced patellofemoral (PF) joint and femoral component in place, soft tissue balance was intra-operatively assessed in CR TKA (n = 20) and PS TKA (n = 20) in osteoarthritic patients. The joint component gap and varus ligament balance at zero, ten, 45, 90 and 135° of knee flexion with the patella reduced were measured.ResultsIn PS TKA, the joint component gap positively correlated with patella height at 90 and 135° of knee flexion. However, there was no correlation between joint component gap and patella height at other flexion angles in PS TKA and any flexion angle in CR TKA. Varus ligament balance showed no significant correlation with patella height in either CR or PS TKA.ConclusionAnalysis of soft tissue balance and patella height only showed a positive correlation in joint component gap at a high flexion angle (90 and 135°) in PS TKA but not in other parameters examined. Pre-operative measurement of patella height may be an important factor for predicting an intra-operative flexion gap in PS TKA.

Matching of Articular Surface Shape of Selected Donor and Recipient Sites for Cylindrical Osteochondral Grafts of the Femur -Quantitative Evaluation using a Three Dimensional Laser Scanner

Objectives: Autogenous osteochondral grafting has been widely performed as the treatment of the focal osteochondral defects. In this procedure, it is ideal and important to match the articular surface shape between the donor and recipient site to reproduce the original articular surface of the femur. The purpose of this study was therefore to investigate the ideal matching pattern of the articular surface profile between the donor and recipient site of the femur using a three dimensional (3D) laser scanning method. Methods: Eleven cadaveric knees were employed for this study. The 3D laser scanner was used to obtain 3D profile of the femur. Firstly, we indicate a point of the joint surface from the obtained mesh data and calculate the normal vector of the indicated point. Moreover, we determine an analysis area of a constant diameter from the normal vector, and calculate the vertical interval (VI) from the highest and lowest points along within the analysis area. For the data analysis, we divided the donor and recipient sites into the 12 areas. In the donor site, the peripheral and middle one-third areas of the femoral articular surface in medial and lateral patellofemoral (PF) joint were extracted and additionally, these areas were divided into 3 areas(proximal / interlevel / distal). In the recipient site, the peripheral, middle and central one-third areas of the articular surface in medial and lateral femoral condyle were extracted and moreover these areas were divided into the contact surface to the tibia in knee extension (anterior) and flexion (posterior). VIs were calculated in each area and we investigated the matching of the articular surface between the donor and recipient site for cylindrical osteochondral grafts of 6, 8 and 10 mm diameter. Results: In the donor site, the VIs of the middle area were significantly smaller than those of the peripheral area. In the recipient site, the VIs of the anterior area were significantly smaller than those of the posterior area. (table1). These results showed that the VIs of the middle area in the donor site showed no significant differences with those of the anterior area in the recipient site. Moreover, the VIs of the peripheral area in the donor site showed no significant differences with those of the posterior area in the recipient site. Therefore, the articular surface profile of these areas matched each other (Fig.1). These VIs and matching patterns of the articular surface profile had a similar tendency in all sizes of osteochondral grafts. Conclusion: We demonstrated the matching of the articular surface shape between the donor and recipient site in autogenous osteochondral grafting. This study indicated that the VI of the middle one-third area in the donor site and the contact surface to the tibia in knee extension in the recipient site was small and the articular surface profile of these areas seemed to be congruent. Moreover, the VI of the peripheral one-third area in the donor site and the contact surface to the tibia in knee flexion in the recipient site was large and the articular surface shape of these areas seemed to be fitting. Considering these matching patterns, surgeons should select the donor site fitting the articular surface profile in the recipient site in order to perform ideal cylindrical osteochondral grafts. As a clinical relevance, this study will be useful for improving the donor site selection as a preoperative planning in this technique by using data derived from CT and MRI scans of the knee.

The diagnostic reliability of the quantitative pivot-shift evaluation using an electromagnetic measurement system for anterior cruciate ligament deficiency was superior to those of the accelerometer and iPad image analysis

PurposeSeveral non-invasive devices have been developed to obtain quantitative assessment of the pivot-shift test in clinical setting using similar but diverse measurement parameters. However, the clinical usability of those measurements has yet to be closely investigated and compared. The purpose of this study was to compare the diagnostic accuracy of three non-invasive measurement devices for the pivot-shift test.MethodsThirty patients with unilateral anterior cruciate ligament (ACL) injury were enrolled. The pivot-shift test was performed under general anaesthesia. Three devices, an accelerometer system (KiRA), an image analysis iPad application (iPad), and electromagnetic measurement system (EMS), were used simultaneously to provide two parameters, namely tibial acceleration monitored using KiRA and EMS, and tibial translation recorded using iPad and EMS. Side-to-side differences in each parameter and correlation between the measurements were tested, and a receiver-operating characteristic (ROC) curve analysis was conducted to compare their measurement accuracy.ResultsSignificant side-to-side differences were successfully detected using any of the measurements (all p < 0.01). KiRA demonstrated moderate correlation with the EMS for tibial acceleration (r = 0.54; p < 0.01), while poor correlation was observed between iPad and the EMS for the translation (r = 0.28; p < 0.01). The ROC curve analysis demonstrated better accuracy for the detection of ACL insufficiency in the EMS than KiRA and iPad for tibial acceleration and translation, respectively.ConclusionsAlthough all three measurements were similarly capable of detecting ACL deficiency, the EMS has the advantage of comprehensive evaluation of the pivot-shift test by evaluating both tibial acceleration and translation with higher accuracy than those of KiRA and iPad. It could be suggested that any of those measurement tools might improve the clinical diagnosis of ACL insufficiency.Level of evidenceDiagnostic study of consecutive patients with a universally applied gold standard, Level Ib.

Post-cam clunk syndrome after posterior stabilized total knee arthroplasty as a sign of early femoral component loosening

Soft tissue impingements are well-known complications of total knee arthroplasty. The impingements usually occur between the medial or lateral femoral component and tibial insert, and between the patella and femoral components. We report a rare case of impingement of the soft tissue between the femoral intercondylar fossa and post of the polyethylene insert, which caused pain and walking disability. After the surgery for the arthroscopic removal of the soft tissue, the symptoms disappeared. However, prosthetic loosening of the femur occurred several months after the arthroscopic surgery, requiring revision surgery. We would propose to call this symptom as post-cam clunk syndrome.

Anterolateral Capsule Injury Did Not Aggravate Rotational Laxity of the Anterior Cruciate Ligament Injured Knees Measured by Quantitative Pivot-shift Evaluation

Objectives: The anterolateral capsule (ALC) injury concomitant with the anterior cruciate ligament (ACL) injured knees has been recently focused with potential effect on the knee rotational laxity. Although some basic in-vitro studies explored the effect of the additional ALC injury, most of such studies utilized their original rotational stress test rather than the clinically-used pivot-shift test. The knee rotational instability should be examined by the clinical pivot-shift test. Some quantitative measurement devices for the pivot-shift test have been clinically available lately. The purpose of this study were to evaluate the pivot-shift test using a quantitative measurement in clinical cases and to compare them between ACL injured knees with and without the ALC injury determined by magnetic resonance imaging (MRI). Methods: Eighty-five unilateral ACL injury patients (40 male and 45 female, age 25.3±11.7 y.o.) who were scheduled to have primary ACL reconstruction were included. Just prior to the ACL reconstruction, the pivot-shift test was performed under anesthesia while making the quantitative evaluation using electromagnetic measurement system (Fig.1). The tibial acceleration (m/sec2) during the pivot-shift was calculated, and the four levels of clinical grading was also determined according to the IKDC (none, glide, clunk, and gross). The concomitant ALC injury in the ACL injured knees was diagnosed on the MRI and divided into two groups ALC injured group (ALC+) and ALC intact group (ALC-). The differences of clinical grading and quantitative measurements were tested between ALC+ and ALC- groups. P-value of <0.05 was considered as statistically significant. Results: Forty-two patients had concomitant ALC injury. 21 knees of ALC+ group were graded as glide in clinical grading, 18 knees as clunk, and 3 knees as gross in ALC+ group, meanwhile 22 knees were assessed as glide, 17 knees as clunk, and 3 knees as gross in ALC- group. There was no difference in clinical grading between ALC+ and ALC- groups (p=0.97). The tibial acceleration measurement during the pivot-shift test demonstrated no significant difference between ALC+ group (1.4±1.2 m/sec2) and ALC- group (1.6±1.3 m/sec2) (p=0.21). Conclusion: This study demonstrated that the ALC injury accompanied with the ACL injury did not have significant effect on the rotational laxity based on either clinical grading or quantitative evaluation. There was a limitation of this study that statistical power was not so strong around 0.6, but, interestingly, the rotational laxity measurements was slightly larger in the ALC intact group. The ALC injury has been advocated as a major factor to aggravate the knee rotational laxity. In this study, however, the impact of the ALC injury on the rotational laxity was not confirmed. Therefore, we should pay more attention to other common and identifiable injures such as meniscus and cartilage tear.

Concomitant Lateral Meniscus Injury Aggravates Rotational Laxity of the Anterior Cruciate Ligament Injured Knees

Objectives: Residual rotational laxity in the anterior cruciate ligament (ACL) reconstructed knees is a remaining problem after the ACL reconstruction. Improper detection and treatment of the secondary restraint for the knee rotational laxity after the ACL were considered as the major reason for the problem. Although anterolateral ligamentous structure of the knee has increasingly been focused on, meniscus injury is frequently accompanied with the ACL injury and assumed to have significant impact on the rotational laxity based on previous studies. The purpose of this study was to determine the effect of the meniscus tear on the rotational laxity in the ACL-deficient knees. Methods: Fifty-seven unilateral ACL-injured patients (26 males and 31 females, 24 ± 10 y.o.) were tested. The protocol of this study was approved by the IRB in Kobe University, and the informed consent was obtained from all the patients. The pivot-shift test was performed under general anesthesia during their ACL reconstruction. (Fig.1) Clinical grading according to the IKDC (none, glide, clunk, and gross) was determined, whereas the quantitative assessment of the pivot-shift was conducted using electromagnetic measurement system to provide the tibial acceleration (m/sec2). Meniscus injuries were finally confirmed under arthroscopy during the ACL reconstruction. The difference of clinical grading and tibial acceleration between the ACL-injured knees with and without additional meniscus tear was assessed, followed by subgroup analysis for each medial and lateral meniscus tear separately. Statistical significance was set at p-value of 0.05. Results: Concomitant meniscus tear was confirmed in 32 knees. Clinical grading was different between the ACL-injured knees with and without meniscus tear (p<0.05), while the quantitative evaluation did not find a statistical significance (meniscus-injured knees 1.6 ± 1.1 m/sec2 vs meniscus-intact knees 1.3 ± 0.8 m/sec2, p=0.09). Subgroup analysis demonstrated increased tibial acceleration in the ACL-deficient knees with lateral meniscus tear (1.8 ± 1.1 m/sec2, n=19) compared to the meniscus-intact knees (p<0.05), whereas the rotational laxity did not rise in the medial meniscus torn knees (1.4 ± 1.0 m/sec2, n=20, p=0.33). Conclusion: Although the meniscus injury is the most common in addition to the ACL injury, the impact of the meniscus injury on the knee rotational laxity has not been fully examined. This study demonstrated the significant impact of the meniscus injury, especially lateral meniscus injury, on the rotational laxity in the ACL-deficient knees, which was successfully detected by using the quantitative measurement device. A careful inspection of the lateral meniscus tear should be required in the ACL-deficient knees with a substantial pivot-shift and, if there is any, it should be repaired as much as possible to avoid additional rotational laxity.