山口 智志

PURPOSE: Several MRI-based evaluation systems for osteoarthritis (OA) of the knee have been developed. Among them the whole-organ magnetic resonance imaging score (WORMS), which evaluates the status of the entire knee joint, appears to be representative. We developed an irregularity index system to measure irregularities of the contours of the femoral condyle on MRI. Only the contour of the condyle was assessed by the irregularity index, whereas several items comprising the knee joint were taken into account by WORMS. This study compared the irregularity index and WORMS in terms of their correlations with clinical scores. METHODS: Thirty-one medial-type OA knees were studied. Kellgren-Lawrence grading was used for X-ray grading: 8 were grade II, 11 were grade III, and 12 were grade IV. Japanese Orthopaedic Association scores and Japanese knee osteoarthritis measure scores were used for clinical assessments. We determined the correlations between MRI-based assessment scores and clinical scores. RESULTS: Both the irregularity index and WORMS exhibited positive correlations with these clinical scores. The irregularity index was associated with bone cysts of the medial compartment and menisci in the articular features of WORMS. CONCLUSIONS: These MRI-based methods are useful for evaluating OA severity. However, the irregularity index may have advantages over WORMS because of its semi-automatic features.

36歳女。2年前より右膝痛が出現し、2ヵ月前より右膝窩〜足底にしびれを認めるようになった。近医でのMRIで右膝窩筋腱部にT1強調画像で低信号、T2強調画像で高信号の多房性嚢胞性病変を認め、ガングリオン疑いで当院紹介となった。当院での再MRIでも同様の所見とT2強調画像で嚢胞内の一部に点状の低信号域を認め、ガドリニウム造影MRIでは病変部に不均一な造影効果を認めた。生検切除術を予定し、まず関節鏡を行い膝上嚢、膝窩筋腱鞘に軽度の滑膜炎所見、外側コンパートメントで脛骨軟骨表面のfibrillationを認めた。次いで、膝関節後方アプローチで進入し、腓腹筋外側頭内側で脛骨後面に嚢胞様の病変部を認め、腱性部を取り囲むように存在したため、これを含めて一塊に切除した。病理所見からは、cystic synovial hyperplasiaの可能性が高いとの結果が得られた。術後2ヵ月で疼痛は完全消失したが、以後も時々軽度の右膝痛があり、術後6ヵ月に対側膝窩部痛が出現し、抗CCP抗体49U/mLが判明したため関節リウマチと診断した。現在も経過観察中である。

BACKGROUND: Alterations in scapular motion frequently are seen in association with various shoulder disorders. It is common clinically to compare the pathological shoulder with the contralateral shoulder, in spite of arm dominance, to characterize the disorder. However, there have been few articles that test the underlying assumption that dominant and nondominant shoulders exhibit comparable dynamic kinematics. The purpose of this study was to compare the 3-dimensional (3-D) scapular kinematics of dominant and nondominant shoulders during dynamic scapular plane elevation using 3-D-2-D (2-dimensional) registration techniques. MATERIALS AND METHODS: Twelve healthy males with a mean age of 32 years (range, 27-36) were enrolled in this study. Bilateral fluoroscopic images during scapular plane elevation and lowering were taken, and CT-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D-2-D registration techniques. Angular values of the scapula and scapulohumeral rhythm were compared between dominant and nondominant shoulders with statistical analysis. RESULTS: There was a significant difference in upward rotation angles between paired shoulders (P < .001), while significant differences were not found in the other angular values and scapulohumeral rhythm. The dominant scapulae were 10° more downwardly rotated at rest and 4° more upwardly rotated during elevation compared to the nondominant scapulae. DISCUSSION/CONCLUSION: Scapular motion was not the same between dominant and nondominant arms in healthy subjects. The dominant scapula was rotated further downward at rest and reached greater upward rotation with abduction. These differences should be considered in clinical assessment of shoulder pathology.

Relatively high rates of loosening and implant failure have been reported after total ankle arthroplasty, especially in first and second generation implants. Abnormal kinematics and incongruency of the articular surface may cause increased loads applied to the implant with concomitant polyethylene wear, resulting in loosening and implant failure. The purpose of this study was to measure three-dimensional kinematics of two-component total ankle arthroplasty during non-weightbearing and weightbearing activities, and to investigate incongruency of the articular surfaces during these activities. Forty-seven patients with a mean age of 71 years were enrolled. Radiographs were taken at non-weightbearing maximal dorsiflexion and plantarflexion, and weightbearing maximal dorsiflexion, plantarflexion, and neutral position. 3D-2D model-image registration was performed using the radiographs and the three-dimensional implant models, and three-dimensional joint angles were determined. The implanted ankles showed 18.1±8.6° (mean±standard deviation) of plantarflexion, 0.1±0.7° of inversion, 1.2±2.0° of internal rotation, and 0.8±0.6mm of posterior translation of the talar component in the non-weightbearing activity, and 17.8±7.5° of plantarflexion, 0.4±0.5° of inversion, 1.8±2.0° of internal rotation, and 0.7±0.5mm of posterior translation in the weightbearing activity. There were no significant differences between the non-weightbearing and weightbearing kinematics except for the plantarflexion angle. Incongruency of the articular surface occurred in more than 75% of the ankles. Our observations will provide useful data against which kinematics of other implant designs, such as three-component total ankle arthroplasty, can be compared.

An irregular contour of the medial femoral condyle (MFC) on magnetic resonance imaging (MRI) appears to indicate the severity of medial-type knee osteoarthritis (OA). The purpose of this study was to establish a system to enable objective assessments of OA knee severity using newly developed software that semi-automatically measures irregularity of the MFC. (1) We evaluated 48 patients aged 50-83 years with 55 knees of medial-type OA. The following scores were recorded: Lysholm score, visual analogue scale (VAS) and the Japanese Knee Osteoarthritis Measure (JKOM). MFC irregularity was automatically calculated by newly programmed computer software. Four parameters for condyle irregularity were calculated: (a) the average thickness of the contour (ATC), (b) the ratio of the upper surface length to the lower surface length of the contour (RUL), (c) average squared thickness of the contour (ASTC) and (d) standard deviation of the contour thickness (SDC). (2) Nine knees that underwent total knee arthroplasty were further analysed histopathologically and compared with irregularity score. Statistically, the RUL and SDC were significantly correlated with the Lysholm score, VAS and JKOM, with good reliability. Histological examinations showed that an irregular contour reflected the density of cystic lesions formed in subchondral bone. An irregularity of MFC on MRI is correlated with OA disease severity clinically and histopathologically. The new computer software is useful to objectively assess OA disease severity.

Knee pain is predominant among osteoarthritis (OA) patients, but the mechanism is poorly understood. We investigated subchondral bone as a source of OA knee pain using immunohistochemistry. Fifteen medial-type OA knees with minimum involvement of the lateral compartment determined by X-ray as well as magnetic resonance imaging that received total knee arthroplasty (TKA) were involved. Each pair of the medial femoral condyle (MFC) and lateral femoral condyle (LFC) was compared obtained at the time of TKA. Osteocartilaginous MFC and LFC specimens were histologically examined and stained with antibodies against cyclooxygenase 1 (Cox-1), cyclooxygenase 2 (Cox-2), substance P, tumor necrosis factor-alpha (TNF-alpha), and neuron-specific class III beta-tubulin (TUJ1), a pan-neuronal marker. Formation of cystic lesions was more frequently seen in the MFC. The lesions were composed of vascular endothelial cells, osteoclasts, and mononuclear cells and were present in similar proportions between the MFC and the LFC. Four out of 15 MFC specimens were positive for Cox-1, 15 for Cox-2, and 13 for TNF-alpha. No LFC specimens were positive for any antibodies. Substance P-positive and TUJ1-positive fibers were found in the subchondral area of the MFC, but not in the LFC. Pathological changes in the subchondral bone can be a source of knee pain, which was detectable by the positive immunoreactivity of substance P, Cox-2, TNF-alpha, and TUJ1, in the subchondral bone of affected compartments. The relatively immediate reduction in pain obtained by TKA might account for the involvement of the subchondral bone in knee pain because most of the affected subchondral plate is excised in TKA (debridement effect of TKA).

BACKGROUND: Understanding the effect of weightbearing on subtalar and ankle joint kinematics is critical for the diagnosis and treatment of foot disorders. However, dynamic in vivo kinematics of these joints are not well studied. The purpose of this study was to compare in vivo kinematics during nonweightbearing and weightbearing activities in healthy subjects. METHODS: Seven healthy subjects with a mean age of 32 (range, 23 to 42) years were enrolled. Oblique lateral fluoroscopic images of nonweightbearing and weightbearing dorsiflexion-plantarflexion activities were recorded. Three dimensional subtalar, ankle, and ankle-subtalar joint complex kinematics were determined using 3D-2D model registration techniques with 3D bone models and single-plane fluoroscopy. RESULTS: During the weightbearing activity from 20 degrees dorsiflexion to 15 degrees plantarflexion, the subtalar joint was significantly more everted, dorsiflexed, and abducted, and the calcaneus showed a significantly more posterior position, than during the nonweightbearing activity. The ankle joint was significantly more plantarflexed and adducted during the weightbearing activity than the nonweightbearing activity. The ankle-subtalar joint complex was significantly more everted, and the calcaneus showed significantly greater posterior position than the nonweightbearing activity. CONCLUSION: These observations provide basic quantitative descriptions of weightbearing and nonweightbearing kinematics for healthy joints. CLINICAL RELEVANCE: These data can serve as the basis for comparison with pathologic feet for both diagnostic and therapeutic purposes.

BACKGROUND: Knee kinematics during pivoting activities are not well studied, but might provide insight critical to understanding the pathology of the anterior cruciate ligament deficient knee. The purpose of this study was to compare in vivo kinematics during weight bearing pivot and squat activities in patients with unilateral anterior cruciate ligament deficient knees, and to contrast those kinematics with the uninjured contralateral knees. METHODS: Eight unilateral anterior cruciate ligament deficient patients with a mean age of 41 (SD 7) years were enrolled. Anterior cruciate injury was confirmed by positive Lachman test and MRI. Lateral fluoroscopic images of pivot and squat activities were recorded for both anterior cruciate ligament deficient and contralateral knees. Three-dimensional tibiofemoral kinematics and centers of rotation for each knee were determined using 3D-2D model registration techniques. FINDINGS: During pivoting, the tibia of the anterior cruciate ligament deficient knee was significantly more anterior than the contralateral knee during tibial neutral to internal rotation. The pivot activity showed lateral centers of rotation in both anterior cruciate ligament deficient and contralateral knees while squatting showed medial centers of rotation. INTERPRETATION: This dynamic method might be useful to objectively characterize restoration of dynamic function in knees with various types of anterior cruciate ligament reconstructions. These results also indicate kinematics during squatting type activities cannot be extrapolated to predict knee kinematics during pivoting types of activities.

Many studies have reported successful outcomes less than 10 years after anterior cruciate ligament (ACL) reconstruction. However, longer-term outcomes have not been analyzed. We assessd outcomes 24 years after anterior cruciate ligament reconstruction with iliotibial tract and compared them with shorter-term results in the same patients. Between 1979 and 1981, 45 patients underwent combined intra- and extra-articular ACL reconstruction with iliotibial tract. Follow-up evaluations of these patients were performed at 6, 13, and 24 years after surgery, which included manual and instrumental laxity testing, functional assessments, and radiography. Twenty-six (60%) patients of the original ACL reconstruction cohort participated in all three follow-up assessments. Three patients had undergone meniscectomy prior to ACL reconstruction and 18 underwent meniscectomy together with ACL reconstruction. Eleven patients underwent subsequent meniscectomy. The mean Lysholm score was 96.2, 93.8, and 87.8 at 6-, 13-, and 24-year follow-up, respectively. A significant decrease in mean Lysholm score was found between 13- and 24-year follow-up. The mean KT-1000 side-to-side difference was 3.5 mm at 24-year follow-up. Overall knee laxity did not change significantly during the follow-up period. At 24-year follow-up, 17 (71%) patients had moderate or severe degenerative changes on radiographs although about 50% of the patients participated in regular sports activities and no patient required regular clinical intervention.