桡骨远端骨折成角改变对桡腕关节影响的生物力学研究

目的:研究桡骨远端骨折后掌倾角及尺偏角改变对桡腕关节的影响.方法:12只成人上肢标本于距关节面3cm处截骨去除1cm骨块,制作桡骨远端骨折成角畸形模型.利用压敏片测试桡腕关节面的应力分布和受力面积改变情况.结果:随着桡腕关节面背倾加大,舟骨和月骨接触面向关节面背侧移位,随着背倾角度和桡偏角度的加大,舟骨的接触面积、接触应力显著减少(P＜0.01),月骨的接触面积、接触应力显著增大(P＜0.01).结论:桡腕关节面背倾10°以上时,桡偏10°以上时,舟骨和月骨的接触面积及接触应力有显著变化,影响腕关节功能.     

可吸收螺钉内固定结合创必复治疗陈旧性舟骨骨折

目的 探讨应用可吸收螺钉(grand fix)内固定结合bFGF生物蛋白海绵(创必复)治疗陈旧性舟骨骨折及骨不连的临床疗效及安全性.方法 对9例陈旧性舟骨骨折按Herbert分型:Ⅲ型6例,Ⅳa型2例,Ⅳb型1例.取桡背侧切口,应用可吸收螺钉内固定,骨折端填塞、覆盖bFGF生物蛋白海绵.结果 9例术后随访时间平均为7.3个月.其中8例舟骨骨折全部愈合,腕关节活动范围:掌屈45.～55.,背伸40°～50°,桡偏20°～25°,尺偏25°～35°;腕部握力平均恢复至健侧的88％.1例舟骨不愈合,骨折端硬化,持重物后疼痛、无力,腕关节活动范围:掌屈20°,背伸25°,桡偏10°,尺偏15°.术后全部患腕均无过敏反应及感染发生.结论 可吸收螺钌内固定结合bFGF生物蛋白海绵治疗陈旧性舟骨骨折,具有生物相容性好、固定可靠、安全性高等优点,可促进舟骨骨折愈合.     

腕投掷运动时腕关节韧带长度变化的活体研究

目的 探讨腕关节在投掷运动过程中腕关节韧带长度的变化.方法 对6例志愿者腕关节进行CT扫描,获取腕关节在投掷运动过程中的5个位置,即桡偏20°背伸60°,桡偏10°背伸30°,中立位,尺偏20°掌屈30°,尺偏40°掌屈60°时各腕骨、尺桡骨远段的三维重建图像,在重建图像基础上利用Mimics软件测得在腕关节投掷运动过程中掌、背侧腕关节韧带的长度.结果 腕关节由中立位至桡偏20°背伸60°时桡舟头韧带、长桡月韧带、尺头韧带、尺三角韧带长度显著伸长,分别延长(3.4±0.5)、(2.0±0.2)、(2.6±0.5)、(2.1±0.4)mm,差异均有统计学意义(P<0.05);腕关节由中立位至尺偏400掌屈60°时背侧桡腕韧带、背侧骨间韧带止于小多角骨部分长度显著伸长,分别延长(1.7 ±0.2)、(3.8 ±0.4)mm,差异有统计学意义(P<0.05).尺月韧带、背侧骨问韧带止于舟骨部分在投掷运动过程中其长度均较中立位时旱增长趋势.结论 腕关节在桡背伸至尺掌屈运动过程中,桡舟头韧带、长桡月韧带、尺头韧带、尺三角韧带缩短,提示张力减低,背侧桡腕韧带、背侧骨间韧带止于小多角骨部分伸长,张力增大,尺月韧带、背侧骨间韧带止于舟骨部分于中立位时张力最小,其变化规律有助于指导临床腕关节韧带损伤的修复.     

腕舟骨骨不连的手术及功能康复

腕舟骨骨折是腕骨中最常见的骨折之一 ,其延迟愈合和骨不连的发生率较高。如何促进骨愈合 ,改善腕关节功能 ,提高手的握力 ,一直是骨科医师所关注的问题[1] 。自 1997年以来采用桡动脉升支的桡骨远端骨膜瓣植入术及加强术后康复指导治疗腕舟骨骨不连 13例 ,效果满意 ,现报道如下。1　临床资料　　本组共 13例 ,男 11例 ,女 2例 ;年龄 2 0～ 35岁 ,平均 2 6岁。伤因 :均为腕极度背伸所致腕舟骨腰部骨折。主诉 :腕部酸痛 ,手握力明显减退 ,腕关节桡偏及背伸活动受限。Ｘ线片示 :腕舟骨腰部陈旧性骨折 ,骨断端硬化 ,近断端有明显囊性变或空洞 ,…     

正常腕关节桡腕关节面应力分布的实验研究

目的　明确正常腕关节桡腕关节面的应力分布特点及其与腕关节位置的关系。方法　 5侧标本通过克氏针固定前臂于中立位 ,调整加载支架 ,使腕关节分别处于中立、掌屈 30°、背伸 30°、尺偏 30°及桡偏 1 0°,通过桡侧、尺侧屈腕肌腱、桡侧、尺侧伸腕肌腱 ,垂直加载 1 2kg固定负荷 ,富士压敏薄膜通过腕关节背侧切口置入 ,应用颜色密度测量仪FPD— 30 5E及密度压力转换器FPD— 30 6E分别测量舟骨窝、月骨窝的应力。结果　舟骨窝及月骨窝内应力分布不同 ,且随腕关节位置的改变而变化。结论　正常腕关节桡腕关节面存在两个相对独立的应力分布区 ;桡舟关节并非紧密嵌合 ,舟骨窝内应力分布不均匀 ;桡月关节在腕关节中立、掌屈、尺偏位时嵌合不紧密 ,月骨窝内应力分布不均 ;而在腕关节背伸、桡偏时嵌合紧密 ,应力均匀分布 ;腕关节背伸位时 ,舟骨窝及月骨窝的应力最大     

股骨内髁游离骨瓣治疗腕舟骨近侧骨折块坏死

目的 探讨以膝降动脉关节支为血管蒂的股骨内髁游离骨瓣治疗腕舟骨近侧骨折块坏死的临床疗效。方法 回顾性分析2018年9月-2022年8月收治的5例股骨内髁游离骨瓣移植治疗腕舟骨近侧骨折块坏死的病例资料。随访数据记录平均28个月(5～52个月)。记录患者年龄、性别、骨坏死持续时间、既往手术次数、骨愈合时间、术后活动范围、疼痛缓解等情况;手术彻底清除了坏死的腕舟骨近端,并重建一个类似于解剖学上带关节面软骨的舟骨凸段。恢复桡舟关节及舟月关节的解剖关系。结果治疗腕舟骨近侧骨折块坏死5例,早期随访愈合时间短,具有100%的骨瓣成活及愈合率,经X线及计算机断层扫描证实平均9周内骨性愈合,所有患者腕部疼痛按VAS评分标准均有明显缓解,其中3例完全缓解,2例不完全缓解。腕部活动范围背伸平均47°(20°～70°)和35°屈曲(15°～60°),桡偏平均22°(15°～30°),尺偏平均28°(20°～35°),与术前测量结果相似(术前平均49°伸展和37°屈曲,平均25°桡偏及31°尺偏);骨瓣供区术后随访功能完全正常。按中华医学会手外科学会腕关节功能评定试用标准：优3例,良2例。结论 带血管蒂及骨软骨...     

桡动脉返支为蒂桡骨茎突骨瓣植入治疗舟骨骨折不愈合

目的分析以桡动脉返支为蒂的桡骨茎突骨瓣移位治疗舟骨骨折不愈合的临床效果。方法对18例舟骨骨折不愈合的患者,我们以桡动脉返支为蒂在桡骨茎突掀起1.5 cm×3.5 cm×0.5 cm的骨瓣,植入沿舟骨纵轴跨越骨折线所凿同等大小的骨槽内进行治疗。舟骨腰部骨折11例,近侧骨折7例,其中5例舟骨近端骨折块伴缺血坏死。腕关节活动疼痛,尤以背伸及桡偏时明显,鼻烟窝处有压痛,腕关节活动受限,X线片示10例患者有骨折端硬化及囊性变,骨折线明显加宽。结果术后18例舟骨骨折均愈合,其中5例合并缺血坏死的舟骨骨折块重新成活,骨折平均愈合时间为4个月。术后获随访12年,患者腕关节活动良好,腕背伸时无疼痛,日常生活和工作无影响。结论采用桡动脉返支为蒂的桡骨茎突骨瓣移位治疗舟骨骨折不愈合及近端骨折块缺血坏死,操作简便,治疗有效,具有一定临床应用价值。     

可吸收螺钉治疗陈旧性腕舟状骨骨折的临床应用

目的 通过自体桡骨远端植骨、可吸收螺钉固定治疗陈旧性腕舟状骨骨折的临床应用,探讨腕舟状骨骨折治疗新方法.方法 2002年1月-2007年5月,应用自体桡骨远端松质骨植骨,聚-DL-乳酸可吸收螺钉治疗陈旧性腕舟状骨骨折18例.其中男13例,女5例;年龄17～41岁.均有手掌撑地外伤史.鼻烟窝及腕舟状骨结节区压痛,握力下降.腕关节背伸(36±2)°,掌屈(30±3)°,桡偏(8±3)°,尺偏(13±2)°结果 18例术后随访3～50个月,平均15.7个月.18例骨折全部愈合,愈合时间为术后3～8个月,平均4.5个月.16例腕关节背伸(68±2)°掌屈(65±3)°,桡偏(15±3)°,尺偏(28±5)°,腕关节活动无疼痛及不适感,无力症状消失.另2例腕关节背伸(40±8)°,掌屈(35±6)°,桡偏(8±5)°,尺偏(12±5)°,与术前相比无明显改善,日常生活中偶有疼痛,腕背伸力量减弱.未发生术后感染及内固定物断裂.结论 可吸收螺钉作为一种新的生物内固定材料治疗陈旧性腕舟状骨骨折,具有生物相容性好、促进骨折愈合、无需二次手术取出等优点.     

不同内固定在舟大小多角骨融合术中稳定性的比较研究

目的 比较舟骨和大、小多角骨(scaphoid-trapezium-trapezoid,STT)融合器与克氏针在STT融合术中内固定强度的差异.方法 12侧新鲜冷冻尸体前臂标本,随机分为融合器组(使用STT融合器)和克氏针组(使用克氏针)2组,模拟进行STT融合术,术后以夹具固定于腕动力测试仪上模拟腕关节主要活动.活动前后均拍摄腕关节标准正侧位X线片,测量桡舟角、桡舟间距、舟骨长度及STT融合体稳定角.结果 融合器组:当腕关节运动范围增加到屈曲45°、背伸40°、尺偏30°、桡偏15°时,客观指标与初始状态相比较变化差异均无统计学意义(P＞0.05).克氏针组:当腕关节运动范围增加到屈曲35°、背伸30°、桡偏10°时,客观指标与初始状态相比较变化差异均有统计学意义(P＜0.05).尺偏30°运动后融合体稳定角与初始状态相比较差异有统计学意义(P＜0.05).结论 STT融合器在舟骨和大、小多角骨融合术中内固定强度大于传统内固定物中的克氏针.     

桡骨茎突部分切除、克氏针张力带固定治疗腕舟状骨骨折

腕舟状骨骨折是腕骨中最常见的骨折，占腕骨骨折的70％～80％。根据Mayo分类．可分为结节部、远端关节面、远端1／3、腰部（中1／3）、近极部5种类型。其中腰部骨折最常见约占全部舟骨骨折的70％，近极骨折占20％，其它类型少见。损伤机理为跌倒手臂前伸着地，桡偏背伸位．手接触地的反作用力通过舟骨向近心端传导，舟骨的桡背侧被桡骨茎突及背侧关节缘阻挡，掌侧有紧张的桡腕韧带压迫，易造成骨折。舟状骨骨折若固定不良，最容易引起骨不连接。本院从2005年7月至2008年7月。采用桡骨茎突小部分切除、克氏针张力带加压固定的方法治疗腕舟状骨骨折18例，取得良好的疗效。     

Biomechanical changes of the wrist flexor and extensor tendons following loss of scaphoid integrity

Loss of integrity of the scaphoid may change the motion center of the entire carpus, and deformities from scaphoid fractures may alter the location of motor tendons of the wrist, thus altering their biomechanics. The goal of this study was to clarify biomechanical changes in these tendons following loss of scaphoid integrity. Excursions and moment arms of the principal flexor and extensor tendons of the wrist were investigated in seven cadaveric upper extremities in intact wrists after simulation of scaphoid waist fracture and after removal of the proximal scaphoid. Excursions of the flexor carpi radialis and ulnaris extensor carpi radialis longus and brevis, and extensor carpi ulnaris tendons were measured with rotary potentiometers during wrist flexion-extension and radioulnar deviation. Simultaneously, wrist joint angulation was recorded. Moment arms of the tendons were derived from tendon excursions and joint motion. After scaphoid fracture, the moment arms of the flexor carpi radialis and extensor carpi ulnaris tendons increased significantly during wrist flexion-extension, whereas the moment arms of the extensor carpi radialis longus and brevis tendons decreased significantly. After proximal scaphoid excision, the moment arms of the extensor carpi radialis longus and brevis tendons again decreased significantly during wrist flexion-extension. The moment arms of the flexor carpi radialis and extensor carpi radialis brevis tendons increased significantly during radioulnar deviation, whereas those of the wrist motors on the ulnar side decreased. These findings indicate the importance of the integrity of the scaphoid in maintaining normal biomechanics of motor tendons of the wrist. An increase in the moment arm of the radial wrist flexor along with a decrease in moment arms of the radial extensors constitutes an etiology for persistent angulation of the scaphoid and the hump-back deformity. In addition, disturbing the biomechanics of the wrist motor tendons predisposes the carpal joints to abnormal loading, potentially contributing to the development of carpal joint degeneration.     

Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis

PURPOSE: To clarify quantitatively the 3-dimensional deformity of the carpus in scaphoid nonunion on the basis of fracture location. METHODS: Three-dimensional computed tomography was used to examine 20 patients with scaphoid nonunion. Displacements of the distal and proximal fragments of the scaphoid, lunate, triquetrum, and capitate were visualized and quantified using a 3-dimensional image-matching technology. Cases were categorized as distal fracture (16 cases) or proximal fracture (4 cases) based on the location of the fracture line relative to the dorsal apex of the scaphoid ridge where the dorsal scapholunate interosseous ligament is attached. RESULTS: The displayed distal scaphoid fractures showed that the proximal fragment of the scaphoid, lunate, and triquetrum rotated into extension and supination. The distal fragment of the scaphoid and capitate translated dorsally without notable rotation. The deformity in proximal fractures was less remarkable than that in distal fractures. Most distal scaphoid nonunions had dorsal intercalated segment instability deformity patterns, whereas a dorsal intercalated segment instability occurred in only 1 case of a proximal fracture. CONCLUSIONS: Whether the fracture line passes distal or proximal to the dorsal apex of the scaphoid determines the subsequent carpal deformity. Dorsal translation of the distal fragment might be one of the factors in the development of degenerative change at the radial styloid.     

桡动脉茎突返支为蒂桡骨茎突骨瓣植入术治疗舟骨骨折不愈合

目的总结以桡动脉茎突返支为蒂的桡骨茎突骨瓣移位治疗舟骨骨折不愈合的临床效果。方法2000年3月~2005年6月,对18例舟骨骨折不愈合的患者,以桡动脉茎突返支为蒂在桡骨茎突掀起1.5cm×3.5cm×0.5cm的骨瓣,植入沿舟骨纵轴跨越骨折线所凿同等大小的骨槽内进行治疗。其中男15例,女3例。年龄18~39岁。舟骨腰部骨折11例,近侧1/3骨折7例,其中5例舟骨近端骨折块伴缺血坏死。腕关节活动疼痛,尤以背伸及桡偏时明显,鼻烟窝处有压痛,腕关节活动受限,X线片示10例患者有骨折端硬化及囊性变,骨折线明显加宽。结果术后18例舟骨骨折均愈合,其中5例合并缺血坏死的舟骨骨折块重新成活,骨折平均愈合时间为4个月。术后获随访1~5年,患者腕关节活动良好,腕背伸时无疼痛,日常生活和工作无影响。结论采用桡动脉茎突返支为蒂的桡骨茎突骨瓣移位治疗舟骨骨折不愈合及近端骨折块缺血坏死,操作简便,治疗有效,具有一定临床应用价值。     

舟月骨间韧带在腕尺桡偏时舟月骨三维运动中的作用

目的 观察在腕关节尺桡偏运动时,舟月骨间韧带(scapholunate interosseous ligament,SLIL)及其各亚区分级切断后对舟骨与月骨三维运动的影响,从亚区水平对SLIL在舟月骨三维运动中的作用进行研究.方法 取12例新鲜冰冻成人上肢标本(左、右侧各6例),共分为正常对照组、断SLIL近侧组、断SLIL近+背侧组、断SLIL近+掌侧组、SLIL全断组(每组6例).采用三维激光扫描及图像重建技术,测定在腕关节尺桡偏时舟骨与月骨的三维运动数据,并进行统计学处理.结果 在正常腕关节做尺桡偏运动时,舟、月骨同时也做尺桡偏运动,但还伴有明显的屈伸方向上的运动;与此同时,舟、月骨还做一定的旋前、旋后活动.在切断近+掌和近+背侧亚区组,舟月骨的活动受到影响.全切断SLIL会导致舟骨掌屈度增加,月骨掌屈活动减弱.结论 采用三维激光扫描及图像重建技术可准确测定腕舟月骨的三维活动度,从SLIL亚区水平上进行的研究表明,部分或全部切断SLIL后会对舟月骨的掌屈程度产生明显影响,但SLIL近侧亚区在控制舟、月骨的活动上不起主要作用.     

桡骨远端骨折术后临床随访及功能恢复不良的分析

目的 回顾性研究金属接骨板固定不稳定桡骨远端骨折的临床效果和功能恢复不良的影响因素分析.方法 对80例(81侧)桡骨远端骨折内固定术后的患者进行随访,平均年龄为59.9岁,平均随访时间为27.2个月.骨折按AO分型:A3 21侧,B1 1侧,B2 1侧,B3 4侧,C1 19侧,C2 24侧,C3 11侧.随访内容包括腕关节疼痛VAS评分,腕关节的主动活动范围,Gartland and Werley评分以及放射学评价.结果 术后腕关节完全无痛64例,轻度疼痛13例,中度疼痛3例,没有发现对疼痛产生影响的因素.腕关节平均掌屈47.5°,背伸61.4°,桡偏21.7°,尺偏34.0°,旋前81.3°,旋后63.0°.共有20侧腕关节的主动活动范围不能达到功能要求.C型骨折显著影响关节的活动范围.按Gartland and Werley评分,优良率为98.8%.放射学检查:腕关节平均掌倾角7.8°,尺偏角24.5°,桡骨高度+2.8 mm;按影像学评分,优良率为91.3%.结论 切开复位金属接骨板内固定治疗不稳定桡骨远端骨折可以获得较好的临床效果.完善术后康复治疗方案可以更好地提高治疗效果.     

Effect of radial shortening on muscle length and moment arms of the wrist flexors and extensors

The purpose of this study was to determine the effect of distal radial shortening on muscle length and moment arm of the wrist flexors and extensors. In eight cadaveric upper extremities, distal radius fractures were simulated by an ostectomy. The distal radius was progressively shortened by 2.5, 5.0, 7.5, and 10 mm. Changes in the resting length of the flexor carpi radialis and ulnaris, extensor carpi radialis longus and brevis, and extensor carpi ulnaris muscles were measured with rotary potentiometers at neutral position, flexion, extension, and radial and ulnar deviation of the wrists. The wrists were passively moved through flexion-extension and radioulnar deviation, and tendon excursions and wrist joint angulation were recorded simultaneously. Tendon moment arms were derived from tendon excursions and joint motion. The results showed that either muscle, length or moment arm of the principal wrist flexors and extensors was significantly affected by the radial shortening. Muscle length decreased significantly after radial shortening in all the wrist flexors and extensors except for the extensor carpi ulnaris. The moment arm of the extensor carpi ulnaris tendon decreased significantly during either wrist flexion-extension or radioulnar deviation. The extensor carpi radialis brevis and flexor carpi ulnaris tendons also showed a significant decrease in their moment arms during radioulnar deviation of the wrist. Radial shortening of only 2.5 mm caused statistically significant changes in muscle length and moment arm of the wrist flexors and extensors. Increasing the extent of radial shortening exaggerated the biomechanical changes in the wrist motors. These results validate the importance of normal radial length for wrist kinetics and, from a biomechanical perspective, support complete correction of radial shortening after distal radius fractures.     

Scaphoid kinematics in vivo

The purpose of this study was to quantify 3-dimensional (3-D) in vivo scaphoid kinematics during flexion-extension motion (FEM) and radial-ulnar deviation (RUD) of the hand. The right wrists of 11 healthy volunteers were imaged by spiral computed tomography during RUD and 5 of those wrists also during FEM. With a matching technique, relative translations and rotations of the scaphoids were traced. Our results showed a broad spectrum of kinematic patterns of the scaphoid during RUD, with small intercarpal motions within the proximal carpal row. Some scaphoids rotated basically around the flexion-extension axis only whereas others rotated almost entirely around the deviation axis during RUD. During FEM we found highly uniform scaphoid motion patterns with large intercarpal motions within the proximal carpal row. These findings suggest that current theories cannot sufficiently explain wrist kinematics and stress the need for more in vivo studies on 3-D carpal kinematics.     

Changes in scaphoid bone density after acute fracture

The radiographic density of the proximal fragments of 16 scaphoid fractures was assessed on scaphoid series radiographs taken at 6 to 12 weeks. In addition, dual energy X-ray absorptiometry measurements of bone mineral density in the distal radius and proximal and distal fracture fragments were performed at 1 to 2 weeks and 6 to 12 weeks. Median reductions of 9% and 10% were observed in bone mineral density in the proximal fracture fragment and the distal radius respectively, but these did not correlate with the radiographic density of the proximal fragment. A greater median reduction in bone mineral density (27%) was observed in the distal fracture fragment and more bone loss occurred at this site when there was an apparent increase in the radiographic density of the proximal fragment (median fall of 0.23 g/cm2 versus 0.14 g/cm2). Thus, apparent increased radiographic density of the proximal fragment may be due to increased bone loss from the distal fragment.     

桡骨远端楔形截骨术治疗腕舟状骨不愈合及月骨坏死

目的评价桡骨远端楔形截骨术治疗腕舟状骨不愈合和月骨坏死的效果。方法应用桡骨远端楔形截骨术治疗腕舟状骨不愈合123例和月骨坏死32例。术中第一截骨线在桡骨茎突近端1.5 cm处,截骨方向与桡骨远端关节面平行;第二截骨线位于第一截骨线近端0.5~1.0 cm处,截骨方向与桡骨纵轴垂直;两截骨线在下尺桡关节中心会合。取出楔形骨块,桡偏使楔形截骨处对合,用1或2枚克氏针固定。结果术后平均随访25(6~60)个月。腕舟状骨折均愈合,平均愈合时间10(8~14)周。32例月骨坏死者中,13例硬化骨重新成活,余无明显改善。术后腕关节疼痛VAS评分、腕关节活动度及握力均较术前明显改善(P0.05);术后患侧腕关节活动度与握力与健侧比较无统计学差异(P0.05)。99例手功能正常,56例有轻微功能障碍。腕关节功能按Krimmer评分:优99例,良56例。结论桡骨远端楔形截骨术治疗腕舟状骨不愈合及月骨坏死的效果确切,操作简单,是值得推荐的一种有效方法 。     

The effects of wrist distraction on carpal kinematics

Changes in carpal kinematics under wrist distraction were studied in fresh cadaveric specimens. A magnetic tracking device measured kinematic motions of the scaphoid, lunate, and third metacarpal relative to the fixed radius in 3 planes of passive motion (coronal, sagittal, and "dart throwers") under progressive distraction loads. The change in percent contribution of the radiocarpal and midcarpal joints was calculated. Radiocarpal motion during extension was decreased as increasing traction was applied, but it increased with flexion. Motion of the scaphoid relative to the lunate was smaller in the oblique plane, resulting in less radiocarpal motion than in the sagittal plane. In the coronal plane, traction had little effect on radial deviation, but ulnar angulation of the scaphoid was greater with ulnar deviation of the wrist. These results suggest that different degrees of tension exist in the palmar and dorsal ligaments with the wrist under traction and during different planes of wrist motion. If wrist motion is desired during fixed traction, such as used clinically with external fixation, the dart-throwers motion (wrist extension with radial deviation and wrist flexion with ulnar deviation) appears to have the least impact on radiocarpal motion. If greater radiocarpal motion is desired, however, such as during postoperative mobilization, flexion-extension and radioulnar deviation will create more radiocarpal motion than the dart-thrower's motion.