佐粧 孝久

腓骨筋内に生じた血腫により亜急性に腓骨神経麻痺を呈した高校サッカー選手の1例を経験したので報告する。症例は16歳男性。サッカー練習中に左下腿の違和感が出現した。5日後に筋力低下を自覚し、その後も増悪するため6日後に当院を受診した。初診時、下腿外側から足背にしびれと痛覚鈍麻を認め、腓骨頭の遠位にTinel様徴候を認めた。筋力は前脛骨筋がMMT4、長母趾伸筋が1と著明に低下していた。MRIで長腓骨筋内にT1強調像で低信号、STIRで高信号と低信号が混在する病変を認め、近位では鏡面形成像を認めた。血腫による腓骨神経麻痺を疑い、神経麻痺が進行していたため手術を行った。手術所見は腓骨筋の断裂とそれによる血腫であり、デブリードマンと血腫の除去を行った。術後は運動、感覚ともに徐々に改善し、3ヵ月で正常に回復し、術後6ヵ月にはサッカーに完全復帰した。(著者抄録)

Anterior dislocation after total knee arthroplasty (TKA) is rare; 9 cases have been reported in the English literature. Five patients sustained subluxation, with recurvatum as the clinical manifestation, and 4 patients sustained complete dislocation, usually accompanying other serious complications. This article describes a case of complete dislocation that developed atraumatically 16 years after TKA and was characterized by dislocation in extension and spontaneous reduction in flexion. Revision TKA was planned, with several alternative procedures under consideration, ranging in degree of invasiveness from simple polyethylene exchange to conversion to a hinge-typed prosthesis. Intraoperatively, extensive areas of blackened synovium and posterior-dominant polyethylene wear existed medially and laterally. Considering the patient's age of 82 years, low activity level in activities of daily living, edematous skin, and number of stable components, we performed simple polyethylene exchange to a cruciate-retaining component that left the partial metal defect in the tibial plate untouched. Successful outcome was achieved for >2 years. The dislocation mechanism was polyethylene thinning, leading to relative valgus and anteroposterior instability that aggravated the anterior cruciate ligament dysfunction, which is speculated as the inherent key causative factor in every TKA. Complete dislocation, usually accompanying other complications, requires prompt treatment because the possibility of serious consequences exists. Due to the absence of a gold standard, the treatment of choice needs to be made on a case-by-case basis.

Thirty-eight patients diagnosed with osteoarthritis underwent 41 cruciate-retaining total knee arthroplasties. In varus and valgus tests at flexion, subjects were seated on a table at 80° of knee flexion; 50 N was applied perpendicular to the lower leg. The factors affecting the postoperative flexion angle were investigated in a multiregression analysis. The mean joint angles of the flexion-valgus and flexion-varus tests were 3.4° ± 1.4° and 6.2° ± 2.5°, respectively. The flexion-varus angle was correlated with the postoperative flexion angle (P < .01). The mean postoperative flexion angles were 110.8° ± 9.6° and 118.1° ± 8.0° in the groups with the flexion-varus angle of 6° or less and more than 6°, respectively (P = .02). Slack lateral laxity in flexion had a significant effect during knee flexion in cruciate-retaining total knee arthroplasty.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To measure superior/inferior translation and external rotation of the humerus relative to the scapula during scapular plane abduction using 3-D/2-D model image registration techniques. BACKGROUND: Kinematic changes in the glenohumeral joint, including excessive superior translation of the humeral head and inadequate external rotation of the humerus, are believed to be a possible cause of shoulder impingement. Although many researchers have analyzed glenohumeral kinematics with various methods, few articles have assessed dynamic in vivo glenohumeral motion. METHODS: Twelve healthy males with a mean age of 32 years (range, 27-36 years) were enrolled in this study. Fluoroscopic images of the dominant shoulder during scapular plane elevation were taken, and computed tomography-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D/2-D model image registration techniques. The kinematics of the humerus relative to the scapula were determined using Euler angles. RESULTS: On average, there was 2.1 mm of initial humeral translation in the superior direction from the starting position to 105° of humeral elevation. Subsequently, an average of 0.9 mm of translation in the inferior direction occurred between 105° and maximum arm elevation. The average amount of external rotation of the humerus was 14° from the starting position to 60° of humeral elevation. The humerus then rotated internally an average 9° by the time the shoulder reached maximum elevation. These changes in superior/inferior translation and external/internal rotation were statistically significant (P&lt .001 and P = .001, respectively), based on 1-way repeated-measures analysis of variance. CONCLUSION: The observed glenohumeral translations and rotations characterize healthy shoulder function and serve as a preliminary foundation for quantifying pathomechanics in the presence of glenohumeral joint disorders. J Orthop Sports Phys Ther 2012 42(2):96-104, Epub 25 October 2011. doi:10.2519/jospt.2012.3584.

Hi-tech knee II CRタイプを用いた後十字靱帯温存型人工型膝関節置換術38例41膝(平均年齢72.8歳)を対象に、TKA後の最大屈曲角度と寄与因子について検討した。全例、内側型OAで、術前の平均FTAは186.4±4.9度、最大屈曲角度は117.3°であった。経過観察期間19.2ヵ月の結果、術後、Knee scoreは91.8点、Function scoreは81.3点へと改善され、屈曲角度は117.3度から114.5度と若干減少していた。また、posterior condylar offset、Joint lineの変化量は1.4、1.3mmとわずかであった。一方、Joint laxityと屈曲角度では屈曲位Lateral laxityが屈曲角度と強い相関が認められた。更に術前屈曲角度を除いた全因子から四つの因子を選択し、全ての組み合わせで重回帰分析を行ったところ、Lateral laxityにて術後の屈曲角度と強い相関が認められた。

Synovial haemangioma of the knee joint is a relatively rare benign condition with around 200 reported cases. We have recently encountered two cases of synovial haemangioma of the knee joint which preoperative MRI had assessed as highly suspect and which arthroscopic resection and subsequent histological examinations confirmed as synovial hemangiomas. Published studies have identified the following as characteristic MRI features of synovial haemangioma: homogenous low intensity to iso-intensity on T1 sequence; and heterogeneous high intensity with low-intensity septa or spots within the lesion on T2 sequence. However, several other intra-knee disorders mimic these characteristics. In our two cases, we found that gadolinium (Gd)-enhanced images, which have been relatively rarely discussed in the literature, were useful for making the diagnosis and for determining the extent of this condition. These images also were very helpful during arthroscopic excision of the lesion. Nonetheless, even after Gd enhancement, differentiating between malignant conditions such as synovial sarcoma and haemangioma solely from MRI findings is still difficult. (C) 2010 Elsevier B.V. All rights reserved.

Partial-thickness articular cartilage defects (PTCDs) do not heal spontaneously and are thought to be a predisposing factor for the development of osteoarthritis. Younger and smaller animals have a better healing capacity for many types of injuries including those to articular cartilage. Our aim was to examine the longitudinal histological changes of immature murine articular cartilage after the creation of small PTCDs and to compare them to PTCDs in mature cartilage. Single linear PTCDs were created in 3-week-old and 16-week-old rats in the direction of joint motion. At 6 and 12 weeks after PTCD creation, histological changes were examined in the defect sites and surrounding cartilage. Immature cartilage showed a higher repair capability than mature cartilage. Although repaired immature cartilage had fibrocartilage, it exhibited better quality than any PTCD model, except for a fetus model and comparable quality to full-thickness cartilage defects (FTCD) after bone marrow stimulation. Elucidation of the underlining mechanisms that immature cartilage possesses for repairing PTCDs is necessary in order to aid the prevention or develop treatment for osteoarthritis.

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. 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. 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. 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 &lt .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. © 2011 Journal of Shoulder and Elbow Surgery Board of Trustees.

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±0.6. mm 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±0.5. mm 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. © 2011 Elsevier Ltd.

BACKGROUND: Platelet-rich plasma is a fraction of plasma in which platelets are concentrated. It is reported to represent a source of multiple growth factors that promote tissue repair. In anticipation of the eventual testing of platelet-rich plasma in anterior cruciate ligament (ACL)-deficient patients, we examined the effect of autologous platelet-rich plasma on human ACL cell function in vitro. METHODS: Fresh blood and ACL remnants were obtained from four patients who underwent ACL reconstruction surgery. Platelet-poor plasma and platelet-rich plasma were prepared from the blood samples. The concentrations of various growth factors in each preparation were tested with use of enzyme-linked immunosorbent assays. Isolated ACL cells were cultured in the presence of 5% fetal bovine serum, 5% platelet-poor clot releasate, 5% platelet-rich clot releasate, or 10% platelet-rich clot releasate. Platelet-rich plasma and platelet-poor plasma releasates were applied to the ACL cells from the same patient autologously. Cell viability and collagen synthesis in each group were analyzed, and semiquantitative gene-expression assays for type-I and III collagen were also performed. RESULTS: The concentrations of the main growth factors (transforming growth factor-beta, platelet-derived growth factor, epidermal growth factor, and vascular endothelial growth factor) were much higher in platelet-rich clot releasate than in platelet-poor clot releasate. In vitro treatment of ACL cells with platelet-rich clot releasate resulted in a significant increase in cell number compared with platelet-poor clot releasate. Total collagen production by the platelet-rich clot releasate-treated cells was significantly higher than that of the platelet-poor clot releasate-treated cells only because of enhanced cell proliferation. There was no significant effect of platelet-rich clot releasate treatment on gene expression for type-I collagen, but expression of type-III collagen was significantly enhanced by the treatment with platelet-rich clot releasate. CONCLUSIONS: These results suggest that autologous platelet-rich plasma can enhance ACL cell viability and function in vitro.

Background: Forearm rotation is an indispensable activity of daily living and comprises complex motions with rotational and translational components. It is thought that changes in these motions with injury or disease may affect diagnostic indices. Several studies have assessed in vivo forearm kinematics with static conditions, but dynamic forearm kinematics have not yet been reported. The purpose of this study was to analyze forearm kinematics during dynamic rotation using radiographic 3D-2D registration methods. Methods: Ten forearms of five healthy males with the mean age of 37 years old were enrolled. Lateral fluoroscopic images were taken during forearm rotation from maximum supination to maximum pronation with their elbows flexed to approximately 45°. Geometric bone models were created from CT scans of the humerus, the radius and the ulna. Three-dimensional kinematics were determined using 3D-2D model registration techniques with the images and models, and the arc of axial rotation of the radius, volar/dorsal translation of the ulna at the distal radioulnar joint and rotation axis of forearm were computed. Findings: The radial rotation arc was 157°. The ulna translated 3.9 mm (SD 1.5 mm) dorsally during activity. The rotation axis of the forearm passed through the center of the radial head and the ulnar head at the 1.9 mm (SD 0.7 mm) posterior from its geometric centroid. Interpretation: The posteriorly deviated rotation axis at the ulnar head may result in the ulnar head translating dorsally during pronation. These data provide a basis for objective assessment of pathological forearm function. © 2010 Elsevier Ltd.

Hi-tech knee II CR typeを用いてTKAを行った変形性膝関節症44例を対象に、「術中の伸展gapと屈曲gapの差(伸展屈曲gap差)」「術後のストレステストによる屈曲位バランス」「屈曲角度」の3点について計測・評価を行い、相互の関連について統計学的に検討した。その結果、術中の伸展屈曲gap差と術後の外反ストレスによる内側開大角度との間に有意な相関が認められ、また内反ストレスによる外側開大角度と屈曲角度との間に有意な相関が認められた。

The purpose of this study was to test if radial shock waves could enhance the introduction of nuclear factor-kappa B (NF-kappaB) decoy oligodeoxynucleotides, which is reported to markedly inhibit NF-kappaB activation and suppress pro-inflammatory cytokine gene expression, using rat Achilles tendon cells. In the presence of NF-kappaB decoy labeled with or without fluorescein isothiocyanate (FITC) in culture media, radial shock waves were applied to the tendon cells in variable conditions and cultivated for 24 h. The transfection rate was assessed by counting FITC-positive cells, and IL-1-induced NF-kappaB activation in the cells was assessed. Radial shock waves significantly enhanced introduction of NF-kappaB decoy-FITC into the tendon cells. IL-1-induced NF-kappaB activation was significantly inhibited by pretreatment of the cells with NF-kappaB decoy combined with radial shock wave exposure. The present study demonstrated the effectiveness of radial shock waves on introduction of NF-kappaB decoy into tendon cells. Radial shock wave treatment combined with local NF-kappaB decoy administration could be a novel therapeutic strategy for chronic tendinopathy.

7歳女児。誘因なく右膝痛と38℃台の発熱が出現した。来院時、右膝関節に腫脹・熱感を認め、歩行困難であり、血液検査では白血球17300/μl、CRP 8.0mg/dlであった。MRIでは関節水症は著明であったが骨髄に輝度変化はなく、骨髄炎は否定された。関節穿刺で混濁著明な黄白色関節液を認め、CTM(230mg/kg/day)の点滴投与を開始した。関節鏡を施行し、関節内全体に軽度充血した滑膜を認めたが、滑膜の増生は膝上嚢のみにみられ、これを培養と病理検査用に採取した後、灌流液で洗浄してペンローズドレーンを留置した。培養でα溶連菌が検出されたため、抗生剤をABPC(400mg/kg/day)に変更した。早期より持続的他動運動を開始し、局所の症状、炎症反応は次第に軽快し、第12病日には点滴を中止してAMPC内服を2週間行った。第15病日にドレーンを抜去し、翌日にCRPは陰性化し、第25病日に退院となった。

15歳男。バレーボール部に所属し、13歳時より左膝の違和感を自覚しており、疼痛が増悪したため受診した。左膝関節内側皮下に可動性のある腫瘤を触知し、左膝可動域(ROM)は伸展-10°、屈曲120°であった。単純X線では大腿骨外側顆膝蓋関節面の骨透亮像と遊離骨片を、CTでは同部位に2×2cm大で深さ3mmの骨欠損像を認めた。MRIのT1強調像で病変部は低輝度領域として描出された。手術を施行し、膝蓋関節面の病変部には不安定な骨軟骨片が存在しており、これを除去したところ欠損部は3×2cm大となった。遊離体は骨成分を有し、軟骨面の変性は軽度であったため骨接合に用いた。脛骨近位より皮質骨を採取して2×20mmの骨釘を3本作成し、骨軟骨片2個の骨層および母床を新鮮化した後、生体吸収性ピン5本と骨釘を用いてこれらを固定した。術後4ヵ月で疼痛、腫脹、ROM制限はなく、X線上の骨透亮像も消失していたため、骨癒合良好と判断してスポーツ復帰を許可した。術後1年で左膝ROMは伸展0°、屈曲145°であり、MRI上の低輝度領域もほぼ消失している。

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-α), 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-α. 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-α, 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). © 2009 Clinical Rheumatology.

症例は37歳女性で、右膝痛と腫脹を主訴とした。小学生時に関節血症が出現し、中学生時に再発した。2ヵ月間に5回の関節穿刺を受け血性関節液であった。疼痛は増強し跛行を呈し、原因検索で施行したMRIで腫瘍性病変を指摘された。膝蓋跳動が陽性で関節穿刺で血性関節液35mlが採取された。膝関節は0°から45°と著明な可動域制限を認め、膝前面に限局した強い圧痛があり、触診できないほどであった。単純X線で異常所見は認めずMRIで膝蓋下脂肪体にT1で高輝度である腫瘍性病変が存在し、ガドリニウム造影MRIで腫瘍病変にほぼ均一な造影効果を認めた。関節鏡では膝蓋下脂肪体から外側谷にかけ、ブドウ房様に微小血管の集簇した腫瘍性病変が存在した。腫瘍性病変を一塊に摘出し、病理検査結果は海綿状血管腫であった。膝前面の疼痛は劇的に改善し圧痛は消失したが、術前より存在した可動域制限は改善せず、術後4週時に0°から60°あったため関節受動術を施行し、術後6ヵ月に関節可動域は0°から110°に改善し、関節血症再発も認めていない。

症例は79歳女性で、歩行困難と左膝の自動伸展不能で受診した。6年前より両膝関節痛および関節可動域制限が出現した。両側変形性関節症の診断で保存加療されたが症状の増悪を認めた。78歳時に人工膝関節置換術(TKA)を施行された。左内側関節裂隙に圧痛を認めたが関節水腫や腫脹は認めなかった。関節可動域は伸展-20°、屈曲110°であった。単純X線でKellgren&Lawrence分類グレード3の関節症変化を認めた。立体FTAは179°であった。左膝蓋骨骨折の既往があったが画像上膝蓋骨の骨折後の変形を認めなかった。術前の計画に従いTKAを施行した。術後5日目にベッドに端座位で座っている状態から転倒し、患側膝を過屈曲した後から、歩行困難、膝痛と伸展障害が出現した。左膝関節の腫脹および膝蓋骨への中枢への変化を認め、膝蓋腱は触知できなかった。受傷後の画像所見で単純X線で膝蓋骨高位を認め、Insall-Salvati indexは2.2であった。脛骨結節の剥離骨折と考えられる2mm程度の小骨片像も認め、TKA術後の膝蓋腱断裂と診断された。

3D-2D registration法を用いて生体における荷重位および非荷重位での足関節底屈運動における距腿関節、距踵関節の3次元動態を定量的に測定・比較した。対象は足関節に外傷・障害の既往がない健常者7名で、平均年齢は32歳であった。方法として脛骨/腓骨複合体、距骨、踵骨の3次元骨モデルを作成してX線画像に投影し、骨モデル輪郭をX線画像の輪郭に合わせることにより、各骨モデルの3次元空間上の位置を決定して距腿関節と距踵関節の3次元動態を測定した。その結果、距腿関節の主な運動は底、背屈であり、荷重位では非荷重位と比べて、より底屈、内転位にあった。距踵関節の主な運動は回内、外であり、荷重位では距腿関節とは逆に、より背屈、外転、回内位にあった。荷重位と非荷重位における関節動態の差は、荷重位では距腿関節、距踵関節が共同して働き、距踵関節の適合性が高まって安定することが示唆された。

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. © 2008 Elsevier Ltd. All rights reserved.