Kazuma Futai

Measurement of the Glenoid Track In Vivo as Investigated by 3-Dimensional Motion Analysis Using Open MRI

Background: A Hill-Sachs lesion is a common injury associated with anterior glenohumeral instability, and a Hill-Sachs lesion that engages with the anterior glenoid rim is 1 factor related to recurrent instability. In a cadaveric study in 2007, a new concept, the “glenoid track,” was proposed to evaluate the risk of engagement of Hill-Sachs lesions with the glenoid. Purpose: To investigate the glenoid track in vivo using a custom-developed noninvasive motion analysis system. Study Design: Descriptive laboratory study. Methods: Using a wide-gantry magnetic resonance imaging (MRI) scanner, the right shoulders of 30 healthy volunteers were examined. The MRI scans were taken of the right arm in 7 static supine positions from 0° to maximum abduction, keeping maximum external rotation and horizontal extension. Using the custom motion analysis system, 3-dimensional models of the scapula and humerus were created from the MRI data. Then, the movement of the humerus and scapula was calculated using voxel-based registration of each model, and the motion of the glenoid on the humeral head was analyzed. Results: The models demonstrated that glenoid contact shifted from the inferomedial to the superolateral portion of the humeral head. The mean widths of the glenoid track with the arm at 60°, 90°, 120°, and 150° of abduction were 20.7 ± 4.5 mm, 19.4 ± 3.9 mm, 18.9 ± 2.7 mm, and 18.7 ± 2.5 mm (89%, 83%, 82%, and 81% of the glenoid width), respectively. The width of the glenoid track at 60° of abduction was significantly greater than those at 90°, 120°, and 150° of abduction (P = .0472, .0148, and .0083, respectively). There were no significant differences among widths measured at 90°, 120°, and 150° of abduction. Conclusion: The existence and widths of the glenoid track were confirmed in vivo.

In vivo kinematics of high-flex mobile-bearing total knee arthroplasty, with a new post-cam design, in deep knee bending motion.

PurposeThe objective of this study was to evaluate the in vivo knee kinematics to assess the available functional motion of the characteristic mobile-bearing prosthesis design and to examine whether the artificial joint would work in vivo according to its design concept.MethodsWe studied 14 knees (11 patients) implanted with the Vanguard RP Hi-Flex prosthesis. This prosthesis has a highly original form of post-cam called a PS saddle design with high compatibility, and with a rotating plate mobile-bearing mechanism. The cylinder-type post-cam is designed to enable contact in early flexion ranges, and to prevent paradoxical anterior femoral component movement. Each patient performed weight-bearing deep knee bending under fluoroscopic surveillance. Motion between each component including the polyethylene insert was analyzed using the 2D/3D registration technique.ResultsThe mean range of motion was 122.0°. The mean femoral component rotation for the tibial tray was 5.0°. No paradoxical anterior movement of the nearest point was confirmed between the femoral component and the tibial tray in the early flexion ranges. Initial contact of the post-cam was confirmed at a knee flexion angle of 33.8°. Subsequently, the wide contact of the post-cam was maintained until flexion reached 120° in all knees, but disengagement of the post-cam was observed in two knees when flexion was ≥130°.ConclusionsThe results of this study demonstrated that the prosthesis design generally works in vivo as intended by its design concept. The present kinematic data may provide useful information for improvement of high-flex type prostheses.

In vivo three-dimensional motion analysis of the shoulder joint during internal and external rotation

PurposeThe purpose of this study was to assess accurately the three-dimensional movements of the scapula and humerus relative to the thorax during internal/external rotation motion with abduction of the shoulder joint.MethodsTen right shoulders of ten healthy volunteers were examined using a wide-gantry open magnetic resonance imaging (MRI) system. MRI was performed every 30° from 90° external rotation to 90° internal rotation of the shoulder joint.ResultsThe contribution ratio of the scapulothoracic joint was 12.5% about the long axis of the humerus during internal/external rotation motion. With arm position changes from 90° external rotation to 60° internal rotation, most movement was performed by the glenohumeral joint. Conversely, at internal rotation of ≥60°, the scapula began to markedly tilt in the anterior direction. At 90° internal rotation, the scapula was significantly tilted anteriorly (p < 0.05) when compared with the other positions.ConclusionsWe clarified the existence of a specific scapulohumeral motion pattern, whereby the glenohumeral joint moves with internal rotation and the scapulothoracic joint moves with anterior tilt together with internal rotation motion of the shoulder joint.

In vivo three-dimensional kinematics of total elbow arthroplasty using fluoroscopic imaging

Higher complication rates and lower survivorship are still seen for total elbow arthroplasties compared to total knee and hip arthroplasties. This is partly due to polyethylene wear of the articular surface induced by excessive articular contact stress during elbow motion. The aim of this study was to dynamically evaluate in vivo three-dimensional elbow motion after total elbow arthroplasty. Twelve patients (15 elbows) who underwent operation with the Osaka University Model Total Elbow System were analysed using X-ray fluoroscopic imaging and a two-dimensional/three-dimensional registration technique, which could accurately estimate the three-dimensional spatial position of components. Valgus/varus angle and rotation between humeral and ulnar components showed wide variations among patients. Elbows with valgus angle and internal rotation >10° could induce edge-loading of the articular surface. Component alignment, articular configuration, and soft-tissue balance can affect the kinematics of total elbow arthroplasty.

Effect of Bankart repair on the loss of range of motion and the instability of the shoulder joint for recurrent anterior shoulder dislocation.

BACKGROUND Bankart repair postoperative complications include loss of shoulder motion and shoulder instability. The primary reason that postoperative complications develop may be excessive imbrication of the anterior band of the inferior glenohumeral ligament (AIGHL) or inadequate repair position. The purpose of this study was to quantitatively evaluate the influence of inadequate repair by computer simulation for a normal shoulder joint. METHODS Magnetic resonance images of 10 normal shoulder joints were acquired for 7 positions every 30° from the maximum internal rotation to the maximum external rotation with the arm abducted at 90°. The shortest 3-dimensional path of the AIGHL in each rotational orientation was calculated. We used computer simulations to anticipate the loss of motion and instability by changing the AIGHL length and insertion sites on the glenoid. RESULTS The AIGHL length measured 50 ± 5 mm at the maximum external shoulder rotation. AIGHL shortening by 3, 6, and 9 mm made the angle of maximum external rotation 80°, 68°, and 54°, respectively. A superior deviation of 3, 6, and 9 mm on the glenoid insertion resulted in a maximum external rotation angle of 85°, 79°, and 77°. An inferior deviation of 3, 6, and 9 mm produced humeral head translation of 1.7, 2.9, and 3.6 mm. CONCLUSION Simulation of both excessive imbrication and deviation of the insertion position led to quantitative prediction of the resulting loss of motion and instability. These findings will be useful for anticipating complications after Bankart repair. LEVEL OF EVIDENCE Basic science study, computer modeling, imaging.

Comparison of a self-administered foot evaluation questionnaire (SAFE-Q) between joint-preserving arthroplasty and resection-replacement arthroplasty in forefoot surgery for patients with rheumatoid arthritis

Abstract Objectives: To clarify the difference of patient-based outcome between joint-preserving arthroplasty and resection-replacement arthroplasty in forefoot surgery for patients with rheumatoid arthritis (RA). Methods: A total of 63 feet of 49 RA patients who underwent forefoot surgery were asked to answer pre-operative and post-operative self-administered foot evaluation questionnaire (SAFE-Q). Patients were treated with either (1) metatarsal head resection-replacement arthroplasty (28 feet, post-operative mean age 63.8 years, follow-up 4.2 years, DAS28-CRP 2.2) or (2) metatarsophalangeal joint-preserving arthroplasty (35 feet, post-operative mean age 63.1 years, follow-up 3.6 years, DAS28-CRP 2.1) at each surgeon’s discretion. Results: Mean pre-operative and post-operative subscale scores of SAFE-Q of group (1) and (2) were as follows. Pain and pain-related [(1) pre-op 36.8 to post-op 75.0 vs. (2) pre-op 42.2 to post-op 82.6], physical functioning and daily-living [(1) 43.2–68.8 vs. (2) 52.778.1], social functioning [(1) 44.3–72.0 vs. (2) 52.5–81.9], general health and well-being [(1) 48.4–68.4 vs. (2) 45.5–84.4], and shoe-related [(1) 30.1–50.3 vs. (2) 30.6–64.4]. Both general health and well-being subscale scores (p < 0.05) and shoe-related subscale scores (p < 0.05) were significantly more improved in group (2) compared with group (1). Conclusions: Joint-preserving arthroplasty resulted in better patient-based outcomes than resection-replacement arthroplasty.

CT-Based Navigation for Total Knee Arthroplasty

Image-free computer-assisted surgery systems have been used worldwide for total knee arthroplasty (TKA). We present a computed tomography (CT)-based system that provides preoperative images. Although there is additional cost for preoperative CT-based navigation, it provides useful kinematic data to surgeons for preoperative planning and in the operating room without imageless navigation. In addition to rotation, varus/valgus instability, and anteroposterior translation data, a recent CT-based navigation system provides information about changes in the lengths of the cruciate ligaments during all ranges of movement. Our preliminary results suggest that intraoperative knee kinematics can predict postoperative in vivo kinematics. Reconstructed knee kinematics is one of the key issues for improving patients’ satisfaction after TKA. The CT-based navigation system also supports the surgical procedure by optimizing soft tissue balance, with good clinical results.

In vivo three-dimensional kinematics of normal knees during different high-flexion activities

Aims In Asia and the Middle‐East, people often flex their knees deeply in order to perform activities of daily living. The purpose of this study was to investigate the 3D kinematics of normal knees during high‐flexion activities. Our hypothesis was that the femorotibial rotation, varus‐valgus angle, translations, and kinematic pathway of normal knees during high‐flexion activities, varied according to activity. Materials and Methods We investigated the in vivo kinematics of eight normal knees in four male volunteers (mean age 41.8 years; 37 to 53) using 2D and 3D registration technique, and modelled the knees with a computer aided design program. Each subject squatted, kneeled, and sat crosslegged. We evaluated the femoral rotation and varus‐valgus angle relative to the tibia and anteroposterior translation of the medial and lateral side, using the transepicodylar axis as our femoral reference relative to the perpendicular projection on to the tibial plateau. This method evaluates the femur medially from what has elsewhere been described as the extension facet centre, and differs from the method classically applied. Results During squatting and kneeling, the knees displayed femoral external rotation. When sitting cross‐legged, femurs displayed internal rotation from 10° to 100°. From 100°, femoral external rotation was observed. No significant difference in varus‐valgus angle was seen between squatting and kneeling, whereas a varus position was observed from 140° when sitting cross‐legged. The measure kinematic pathway using our methodology found during squatting a medial pivoting pattern from 0° to 40° and bicondylar rollback from 40° to 150°. During kneeling, a medial pivot pattern was evident. When sitting cross‐legged, a lateral pivot pattern was seen from 0° to 100°, and a medial pivot pattern beyond 100°. Conclusion The kinematics of normal knees during high flexion are variable according to activity. Nevertheless, our study was limited to a small number of male patients using a different technique to report the kinematics than previous publications. Accordingly, caution should be observed in generalizing our findings.

AB0353 In vivo kinematics of three-component mobile-bearing total ankle replacement for rheumatoid arthritis during non-weightbearing plantarflexion/dorsiflexion.

Background Total ankle replacement (TAR) that can relieve pain while retaining ankle movement is a useful surgical option for patients with rheumatoid arthritis (RA). However, high complication rates and low survivorship are still problematic in TAR, as compared to total knee and hip replacements. A better understanding of ankle kinematics including three-dimentional (3D) dynamic motion after TAR should be important to explain the failures in TAR, especially those attributed to loosening and subsidence. We have developed a 3D kinematic analysis system using X-ray fluoroscopic imaging with quantitative assessment of 3D dynamic motion of artificial implants under clinical conditions. Objectives The objective of this study was to determine in vivo kinematics of TAR in rheumatoid ankle and, in particular, to elucidate the dynamic motion of ankle after TAR by 3D evaluation of fluoroscopic imaging. Methods We examined the evaluation of the accuracy of 2D/3D registration technique for TAR systems by computer simulation. We investigated 12ankles in 9 patients with RA implanted with a three-component mobile-bearing TAR (FINE Total Ankle System, Nakashima Medical, Okayama, Japan), which allows not only internal/external rotation but also anteroposterior (AP) translation. Fluoroscopic images were obtained while each patient was asked to perform non-weightbearing maximal plantarflexion and dorsiflexion on the implanted ankle. Thereafter tibio-talar motion was analyzed by 2D/3D registration technique; a reproduction method of the spatial position of each component in TAR, from single-view fluoroscopic images by use of computer-assisted design models. We evaluated the angles of plantar-/dorsiflexion, internal/external rotation, and inversion/eversion as well as AP translation, between the components. Results The accuracy of 2D/3D registration technique was within 0.6° for all rotations, and 0.2 mm for in-plane translations. The average range of tibio-talar motion during the non-weightbearing activity was 19.1±4.7° (mean ±standard deviation) of plantar-/dorsiflexion. Also, as the ankles moved from maximal plantarflexion to maximal dorsiflexion, they demonstrated external rotation, eversion and anterior translation with the average range of 2.9±1.5°, 1.9±1.1°, and 2.1±0.9 mm, respectively. Conclusions In this study, accurate evaluation of 3D dynamic motion of ankle joint after TAR was feasible. Although mobility of plantar-/dorsiflexion was unexpectedly small, and rotation and inversion/eversion was much more insignificant, kinematic patterns were similar to those of normal ankle. From these results, we think that the analysis of in vivo kinematics of TAR using 2D/3D registration technique will provide useful data for comparison not only between the implants but also between the patients. References Nishikawa M. Int Orthop 2004;28:123-126. Shi K. J Foot Ankle Surg 2006;45:316-321. Zuffi S. IEEE Trans Med Imaging 1999;18:981-91. Yamazaki T. IEEE Trans Med Imaging 2004;23:602-612. Komistek RD. Foot Ankle Int 2000;21:343-350. Satoshi Y. J Biomech 2011;44:995-1000. Disclosure of Interest None Declared

AB0354 In vivo kinematics of three-component mobile-bearing total ankle replacement for rheumatoid arthritis during gait.

Background The standard treatment for end-stage arthritis of ankle joint due to rheumatoid arthritis (RA) has been arthrodesis. It is often that patients with RA who require ankle surgery already have destruction of peritalar joints. Since fusion of both the ankle and peritalar joints inevitably results in serious functional problems, total ankle replacement (TAR) that can relieve pain while retaining ankle movement should be useful for patients with RA, especially for those who require peritalar fusion. However, previous studies of conventional TAR have been reported high complication rates and low survivorship, as compared to total knee and hip replacements. This could have primarily been due to excessive contact stress at the relatively small area of ankle joint, and also to the constrained design of the implant. It is expected that recently developed TAR with mobile insert could demonstrate better kinematics than conventional ones, leading to durability of implant as well as maintenance of function. Objectives The objective of this study was to determine in vivo kinematics of a three-component mobile-bearing TAR in rheumatoid ankle during gait. Methods We investigated 12ankles in 9 patients with RA implanted with a three-component mobile-bearing TAR (FINE Total Ankle System, Nakashima Medical, Okayama, Japan), which allows not only internal/external rotation but also anteroposterior (AP) translation. Fluoroscopic images were obtained while each patient was asked to perform gait with full weight-bearing on the implanted ankle. Thereafter tibio-talar motion was analyzed by 2D/3D registration technique; a reproduction method of the spatial position of each component in TAR, from single-view fluoroscopic images by use of computer-assisted design models. We evaluated the plantar-/dorsiflexion angle, internal/external rotation angle and AP translation between the components. Results The average range of tibio-talar motion during the stance phase of gait was 11.0±2.6° (mean ±standard deviation). The average range of internal/external rotation was 3.9±1.3°. However, large intersubject variability resulted in the lack of a uniform pattern of rotational movement. The average amount of AP translation was 1.6±0.7 mm. Conclusions Mobility of plantar-/dorsiflexion was unexpectedly small during the stance phase of gait, whereas rotation and AP translation was much more insignificant. Also, there was wide inter-subject variability in the original rotational and AP translational position of the components, some of which were regarded as malposition. These results suggest that mobile-bearing TAR could have potential advantage in durability with expectation that it could compensate a certain malposition of the components. References Nishikawa M, Tomita T, et al. Int Orthop 2004;28:123-126. Shi K, et al. J Foot Ankle Surg 2006;45:316-321. Zuffi S, et al. IEEE Trans Med Imaging 1999;18:981-91. Yamazaki T, et al. IEEE Trans Med Imaging 2004;23:602-612. Komistek RD. Foot Ankle Int 2000;21:343-350. Conti S. Foot Ankle Int 2006;27:980-984. Leszko F. Foot Ankle Int 2008;29:1117-1125. Satoshi Y, et al. J Biomech 2011;44:995-1000. Disclosure of Interest None Declared