Reconstruction of the hip. A mathematical approach to determine optimum geometric relationships.

The normal mechanical function of the hip is substantially altered by a variety of disorders. The surgical treatment of such conditions, particularly total hip replacement, offers the opportunity not only to replace the articular surfaces of the joint, but also to improve long-term mechanical function by reducing the loads on the joint. A mathematical model of the hip was developed to evaluate the effects of such surgically achievable mechanical alterations as acetabular placement, femoral shaft-prosthetic neck angle, neck length of the femoral prosthesis, and transfer of the greater trochanter. The loads on the hip were lowered significantly by placing the center of the acetabulum as far medially, inferiorly, and anteriorly as was anatomically feasible. Minimum joint contact forces occurred when the femoral shaft-prosthetic neck angles were small, while the minimum moments about the prosthesis stem-neck junction were found when the angles were 130 to 140 degrees. A neck length of the femoral prosthesis of thirty-five millimeters resulted in moments that were lower than those for a neck length of forty-five millimeters. Lateral transfer of the greater trochanter reduced hip-joint forces and moments but distal transfer had little mechanical effect.     

Verbesserte Implantationstechnik der Oberflächenendoprothese des Hüftgelenks

OBJECTIVE: Prevention of incorrect positioning of the surface replacement, whereby the center of the femoral head for the implantation of the replacement surface is ascertained by central drilling of the femoral neck under image intensifier control. INDICATIONS: An arthritically damaged, but not too severely deformed femoral head that can be reamed without injuring the femoral neck. CONTRAINDICATIONS: Hip ankylosis. Femoral head necrosis. Severe deformity of the femoral head. State after varus osteotomy. SURGICAL TECHNIQUE: Using a 6-mm drill bit, the femoral neck of the affected hip is drilled from lateral to medial under anteroposterior and lateral imaging deliberately perforating the femoral head. The hip joint is exposed through a minimized invasive anterolateral, lateral, or posterior approach and dislocated. A guide rod corresponding in size to the 6-mm drill channel is inserted into the drill hole; it serves as a guide for all subsequent preparations of the femoral head, depending on the type of prosthesis. After implantation of the corresponding acetabular component, resurfacing of the femoral head is done. Reduction of the joint completes surgery. RESULTS: In the first 14 hips the midpoint of the femoral head was ascertained by using the manufacturer's centering device. In 31 subsequent hips the midpoint of the femoral head was found by central drilling of the femoral neck. Using the centering device, the average deviation of the angle of the prosthesis from the preoperative CCD angle was 7 degrees (+/- 5.7 degrees ); for central drilling of the femoral neck it was only 3 degrees (+/- 3.4 degrees ). The exact alignment of the resurfacing component is crucial for the success of surgery. It is achieved with greater precision with central drilling of the neck than with the manufacturer's centering device.     

髋表面置换股骨侧假体外翻位植入后股骨近端应力变化的有限元分析

目的 探讨髋表面置换股骨侧假体外翻位植入后股骨近端的应力变化,并寻求最佳外翻植入角度.方法 建立正常股骨近端髋表面置换股骨侧假体(Wright假体)三维模型,其中股骨假体按解剖颈干角(本文选用股骨模型的生理解剖颈干角为135°)、外翻5°、10°、15°植入,加载关节合力及相关肌肉的肌力负荷,分析假体植入前后股骨近端的应力分布变化,并对股骨近端假体周围区域骨质应力分布进行分区量化研究.结果 股骨假体轻度外翻植入降低了股骨头颈交界处上方(2、8区)的应力,5°外翻植入股骨头上方假体杯下缘(1、7区)应力遮挡最小,股骨颈下方(4、10区)应力分布更接近正常股骨.结论 外翻5°植入假体股骨近端应力更接近正常股骨,降低了股骨颈骨折和假体松动的危险.     

Long-term results after open reduction of developmental hip dislocation by an anterior approach lateral and medial of the iliopsoas muscle

The technique of and especially the approach to open reduction of developmental dislocation of the hip are still a matter of discussion. The anterior approach, first lateral and then medial to the iliopsoas muscle, was described by Tonnis in 1978. A follow-up investigation to adulthood has now been performed. Eighty-seven children (118 hips) out of 105 children (83%) who underwent open reduction of developmental dislocation of the hip before the age of 4 years were reinvestigated 10-21 years after the operation. An anterior approach first lateral, then medial to the iliopsoas muscle was chosen, because this offers the best access to the joint. Additional operations including transiliac osteotomy for acetabuloplasty, shortening osteotomy, and femoral osteotomies were performed as necessary. In 92 (78%) of the 118 hips studied the CE angle exceeded 25 degrees and in 98 hips (83%) the VCA angle exceeded 25 degrees. Critical CE angles between 20 and 25 degrees were found in 14% of the hips, and critical VCA angles in 4%. Residual dysplasia (<20 degrees) was found in 8 and 13% of the hips, respectively. Avascular necrosis according to Hirohashi was observed after operation in grade 1 in 5.9% and grade 2 in 1.7%. No necrosis was found following shortening osteotomy of the proximal femur. The anterior approach, first lateral, then medial to the iliopsoas muscle, offers an optimal access to the medial parts of the joint with control of reduction, protects the vasculature of the femoral neck, and allows simultaneous postero-lateral capsulorrhaphy and pelvic osteotomies.     

Computer modeling of the pathomechanics of spastic hip dislocation in children.

Spastic muscles about the hip cause subluxation, dislocation, and lead to acetabular dysplasia. Spastic hip disease occurs when the muscles about the hip exert forces that are too high or in the wrong direction or both. To determine the role of the hip forces in the progression of spastic hip disease and the effect of both muscle-lengthening and bony reconstructive surgeries, a computerized mathematical model of a spastic hip joint was created. The magnitude and direction of the forces of spastic hips undergoing surgery were analyzed preoperatively and postoperatively to determine which procedure is best suited for the treatment of spastic hip disease. The muscle-lengthening procedures included (a) the adductor longus, (b) the psoas, iliacus, gracilis, adductor brevis, and adductor longus, and (3) the psoas, iliacus, gracilis, adductor brevis, adductor longus, semimembranosus, and semitendinosus. The bony reconstructive and muscle-lengthening procedures included (a) lengthening the psoas, iliacus, gracilis, adductor brevis, adductor longus, semimembranosus, and semitendinosus combined with changing femoral neck anteversion from 45 to 10 degrees , (b) lengthening of the psoas, iliacus, gracilis, adductor brevis, adductor longus, semimembranosus, and semitendinosus combined with changing neck-shaft angle from 165 to 135 degrees , and (c) lengthening of the psoas, iliacus, gracilis, adductor brevis, adductor longus, semimembranosus, and semitendinosus combined with changing femoral neck anteversion from 45 to 10 degrees and neck-shaft angle from 165 to 135 degrees . Results show that a child with spastic hip disease has a hip-force magnitude 3 times that of the a child with a normal hip in the normal physiologic position. Based on this mathematical model the best to normalize the magnitude of the hip-joint reaction force, the muscles to be lengthened should include the psoas, iliacus, gracilis, adductor brevis, and the adductor longus. To normalize the direction of the hip force, the extremity should be positioned in the normal physiologic position. The impact of decreasing the femoral anteversion or femoral neck-shaft angle or both had little additional effect on the direction or magnitude of hip forces.     

Orientation of the femoral component in surface arthroplasty of the hip. A biomechanical and clinical analysis

BACKGROUND: Although the orientation of the femoral component has been shown to influence the outcome of total hip replacement, its effect on the clinical outcome of surface arthroplasty has not been studied, to our knowledge. The purpose of this study was to examine the relationship between femoral component positioning and the outcome of a surface arthroplasty of the hip. METHODS: We reviewed the results of ninety-four hybrid metal-on-metal surface arthroplasties in patients who were forty years old or younger at the time of the operation and were followed for a minimum of two years or until the prosthesis failed. Measurements of the hip reconstruction were made on the anteroposterior pelvic radiograph. The correlation between the orientation of the femoral component and the outcome of the arthroplasty was evaluated, as were stresses within the resurfaced femoral head as a function of the orientation of the femoral component. RESULTS: The mean duration of follow-up was 4.2 years. Thirteen hips had an adverse outcome, defined as conversion to a total hip replacement, radiolucency of >1 mm in thickness adjacent to the femoral stem, or narrowing of the femoral neck of >10%. The mean femoral stem-shaft angle in the coronal plane was 138 degrees, with the hips that had an adverse outcome having a significantly lower mean angle than the rest of the cohort (133 degrees compared with 139 degrees, p = 0.03). Hips with an angle of 相似文献   

人工髋关节置换治疗高龄股骨颈骨折

目的探讨高龄股骨颈骨折人工髋关节置换的疗效。方法采用髋关节后外侧人路对58例（58髋）高龄股骨颈骨折患者行人工髋关节置换。结果经过3～19（8．5±0．5）个月随访，58例术后2～3周均恢复行走活动，无1例死亡。按髋关节功能Harris评分标准：优21例（21髋），良31例（31髋），可4例（4髋），差2例（2髋），优良率89．7％。结论人工股骨头或全髋关节置换术是治疗高龄股骨颈骨折的有效方法，可早期活动，恢复关节功能，提高生存质量。     

全髋关节表面置换术治疗成人髋关节发育不良中假体的安放技术和临床疗效分析

目的探讨全髋关节表面置换术治疗髋关节发育不良（DDH）术中假体安放位置的控制和临床效果。方法2005年1月至2007年9月，对42例45髋因DDH继发骨关节炎的患者行全髋关节表面置换术。其中女39例，男3例，平均年龄46．3岁，单侧39例39髋，双侧3例6髋。按Crowe分型，Ⅰ型17例18髋，Ⅱ型17例19髋，Ⅲ型6例6髋，Ⅳ型2例2髋。术前通过CT三维重建测量股骨颈干角、股骨颈前倾角。入路采用改良后外侧Gibson入路，根据术前测量结果，对于颈干角小于135°，手术时适当增加至135°，大于135°则维持原有角度；DDH患者股骨前倾角均有增加，术中应适当减少，并减少髋臼前倾角和外展角。采用X线检查和Harris功能评分评估术后疗效。结果术前股骨颈干角平均134．1°，术后平均138.2°，其中术前颈干角小于135°的34髋，平均131．7°，术后平均137°；术前颈干角大于135°的12髋，平均140.9°，术后平均141．5°。股骨前倾角术前平均34．5°。术后X线显示所有髋臼均为真臼重建，髋臼外展角平均42°。双侧肢体长度差别术前平均2.1cm，术后平均0．5cm。平均随访14．6个月。Harris功能评分术前平均43．6分，最后一次随访功能评分为平均88．4分。随访期内无股骨颈骨折和假体松动等并发症发生。结论对年青DDH并骨关节炎患者采用髋关节表面置换术的近期效果满意，术中根据个体情况调整假体安放位置有助于提高临床效果。     

Telemetric force measurements across the hip after total arthroplasty

A telemeterized total hip prosthesis was implanted in one patient and force-data were obtained. Thirty-one days postoperatively, the magnitude of the joint-contact force during double-limb stance was 1.0 times body weight. During ipsilateral single-limb stance the joint-contact force was 2.1 times body weight, and during the stance phase of gait the peak force typically was 2.6 to 2.8 times body weight, with the resultant force located on the anterosuperior portion of the ball. During stair-climbing, the force was 2.6 times body weight. At peak loads, the angle between the resultant force and the axis of the neck was 30 to 35 degrees and that between the resultant force and the plane of the prosthesis was 20 degrees. During stair-climbing or straight-leg raising, the out-of-plane orientation of the resultant force increased substantially. These data provide information concerning the forces that must be sustained by prosthetic hip joints during a number of common activities of daily living within the first month after implantation. The results also provide insight into the progression of early recovery and demonstrate the variety of forces that are generated during this period.     

Anthropometric study of the hip joint in Northeastern region population with computed tomography scan

Background:

Anthropometric study of the hip joint has important clinical implications and is largely unknown for the northeastern region of India. The purpose of this study is to determine the anatomic variation of the normal hip joint among the people of the northeastern region and to statistically compare them with the available data worldwide.

Materials and Methods:

We evaluated 104 individuals with normal hip joints and of different ethnic backgrounds (Caucasoid and Mongoloids) clinically and by plain x- ray. One topogram of the hip joint, one axial section of the femoral head and femoral condyles of the individual was taken on CT scan. Twelve cases had center edge angle (CE) angle less than 20° (unilateral/bilateral), were considered to be dysplastic and were excluded from the study. Thus the present study includes 92 individuals (184 normal hips, Mongoloids = 45; Caucasoid = 47) between 20-70 years of age. We calculated the mean of the CE angle, acetabular angle, neck shaft angle, acetabular version, femoral neck anteversion, acetabular depth and joint space width in both sexes.

Results:

The mean parameters observed were as follows: acetabular angle 39.2°, centre edge angle 32.7°, neck shaft angle 139.5°, acetabular version 18.2°, femoral neck anteversion 20.4°, acetabular depth 2.5 cm and joint space width 4.5 mm.

Conclusion:

The parameter and its values in our series shows differences when compared to the other western literatures. The neck shaft angle and the femoral neck anteversion in our individuals was 5-6° more than the western literature. The remaining parameters were less or equal to the western literature.     

无柄人工髋关节置换术的初步临床应用

目的 评价无柄人工髋关节置换术的早期随访结果,探讨其临床应用的安全性及可行性.方法 2002年2月至2007年3月,对51例56髋施行无柄人工髋关节置换术.男31例34髋,女20例22髋;年龄25～87岁,平均56.2岁.术前髋关节Harris评分平均(72.4±8.4)分.新鲜股骨颈骨折6例6髋,股骨颈骨折继发股骨头坏死4例4髋,股骨头缺血性坏死(FicatⅢ-Ⅳ期)34例37髋,强直性脊柱炎髋关节强直2例3髋,类风湿髋关节炎2例3髋,髋关节结核3例3髋.全髋关节置换50髋,半髋关节置换6髋.以Harris评分评价术后疗效,用Amstutz分区方法对X线片进行分区评价,观察假体位置及并发症情况.结果 全部病例随访2～7年,平均4.8年.髋关节Harris评分平均(92.8+3.2)分,其中优44髋、良7髋、可4髋、差1例,优良率91%.术后第2,3天发生关节脱位2例,经手法复位成功;术后40天发生感染1例,行关节腔病灶清除及持续关节腔冲洗后治愈;术后半年髋区疼痛1例,行有柄全髋关节翻修.随访期间X线片未见关节松动、脱位及螺钉松动、断裂等情况.结论 无柄人工髋关节置换术可保留股骨颈,创伤小、出血少易于于翻修,适合高龄体弱及年轻患者.早期疗效可靠,远期疗效有待进一步观察.     

258髋Corail股骨柄假体中期疗效观察

目的：探讨终末期髋关节疾病患者采用 Corail 羟基磷灰石(Hydroxyapatite,HA)全涂层股骨柄假体行全髋关节置换术(Total hip arthroplasty, THA)的中期疗效。方法：回顾性分析2011年 1 0月～2019 年 10月采用 Corail 假体行 THA 治疗 239例（258髋）髋关节终末期疾病患者的病例资料,其中男137例,女102例,年龄38~79岁,平均50.4岁。左髋117例,右髋141例。适应症包括股骨头缺血性坏死145髋（56.2%）,髋关节发育不良58髋（22.4%）,髋关节骨性关节炎36髋（14.0%）,股骨颈骨折11髋（4.3%）,类风湿关节炎8髋（3.1%）。采用 Harris 评分、疼痛视觉模拟评分（VAS）及临床并发症评估患者髋关节功能,随访X 片观察假体有无松动、螺钉有无断裂等。结果：所有患者均安全度过围手术期。术后1例患者出现肺部感染伴胸腔积液,术后6例患者术侧大腿出现了不同程度的疼痛,术后5例患者出现假体感染,术后6例患者出现脱位,术后7例患者出现小腿肌间静脉血栓,术后15例患者出现了假体下沉,未出现无菌性松动或神经血管损伤等并发症,无翻修患者,股骨柄存活率为100%。术后239例（258髋）均获随访,随访时间0.5~7年,平均5.8年,末次随访Harris评分（84.84±5.65）分、VAS评分（1.11±0.79）,所有的股骨柄都非常稳定,没有透亮线的迹象。结论：Corail HA 全涂层股骨柄假体具有持久的稳定性,术后大腿疼痛发生率较低等优点,中期疗效较好。     

Influence of acetabular coverage on hip survival after free vascularized fibular grafting for femoral head osteonecrosis

BACKGROUND: Osteonecrosis of the femoral head frequently results in collapse of the head and subsequent arthrosis of the joint. Surgical treatment has been based entirely on the evaluation of the femoral side of the hip joint, with little consideration given to the possible influence on outcome of the orientation of the acetabulum. METHODS: We retrospectively reviewed a consecutive series of 200 hips in 160 patients with osteonecrosis of the femoral head who had undergone free vascularized fibular grafting between 1997 and 1998. The mean duration of clinical follow-up was 7.5 years. Ninety-one hips in seventy-one patients were evaluated radiographically for evidence of progression of femoral head collapse at a minimum of two years, and a mean of three years, postoperatively. We defined conversion to a total hip arthroplasty and progression of femoral head collapse as the failure end points, and we analyzed the association of the acetabular center-edge angle of Wiberg, the area and laterality of the lesion, the amount of preoperative collapse of the femoral head, and the etiology of the osteonecrosis with the likelihood of failure. RESULTS: Forty-eight (24%) of the 200 hips had undergone conversion to a total hip arthroplasty at the time of the final clinical follow-up. In addition, 15% (fourteen) of the ninety-one hips with sufficient radiographic follow-up demonstrated progression of femoral head collapse at the time of the final radiographic examination. Of the hips with a center-edge angle of 30 degrees , 10% had progressive collapse (p = 0.002) and 6% were converted to a total hip arthroplasty (p < 0.001). Neither the etiology nor the size of the lesion was significantly correlated with progression of collapse or conversion to a total hip arthroplasty. CONCLUSIONS: Patients with osteonecrosis of the femoral head and a suboptimal center-edge angle of the hip are at substantial risk for progression of femoral head collapse and conversion to a total hip arthroplasty following free vascularized fibular grafting. An estimation of the degree of hip dysplasia should be included in the preoperative assessment of patients with osteonecrosis of the femoral head for prognostic and possibly surgical planning purposes.     

数字技术在人工全髋关节置换术中的应用研究

目的探索把数字技术应用于人工全髋关节置换术,为临床选择更适配的人工全髋关节假体提供新的方法。方法6例成人病变的髋关节和42-56号的髋臼假体和01-04号钛合金股骨柄(矩形,HA微孔)假体连续CT扫描,将CT扫描数据经Mimics软件处理,3D计算建立髋关节和假体的数字模型。将数据输入SPSS 17.0进行统计学分析。根据术前选择的假体施行手术,术后6个月根据Harris评分进行评价,并与同期6例行传统人工全髋关节置换术患者髋关节Harris评分进行统计学比较。结果 6例骨盆三维模型数据测量结果分析:髋臼前倾角、外展角与身高、性别、侧别因素无显著性差异;股骨颈前倾角及颈干角与侧别、性别及身高因素无统计学差异。结论数字技术可以指导选择更匹配的全髋关节假体,提高人工全髋关节置换术的近期效果,为临床术前选择全髋关节假体提供一种新的方法。     

生物型髋关节假体位置参数与患者生命质量相关性研究

目的分析初次生物型全髋关节置换术(THA)后假体位置重建情况,探讨假体位置参数与患者生命质量的相关性,总结假体位相参数的安全范围。 方法对南京市六合区人民医院骨科2013年3月至2015年3月52例因股骨颈骨折行初次生物型全髋关节置换术的患者进行2年的前瞻性研究。术后第3天未负重前首次拍摄患侧髋关节正侧位及骨盆正位X线片,分析髋臼及股骨柄假体的位置参数,包括髋臼外展角、髋臼前倾角、股骨头旋转中心、股骨垂直偏距、股骨偏心距、外展肌力臂、重力力臂、股骨柄内外翻、颈干角。术前和术后24个月对患者进行评估健康相关生命质量的SF-36简明健康状况调查量表(SF-36)评分。采用SPSS 17.0软件对量表进行Cronbach's (系数同质性分析、Pearson相关分析、因子分析及t检验以评价其信效度,并评价假体位置参数与SF-36各项评分提高值之间的相关性。 结果52名患者(52髋)均完成了随访,根据THA术后首次X线片获取假体位置参数。除情感职能外,手术前后的SF-36量表内部一致性显示Cronbach's α系数>0.7;重测信度显示相关系数(CC)ICC>0.8;分半信度显示Pearson相关系数>0.874;反应度显示SF-36量表能较好地反应THA患者手术前后的生命质量变化状况;结构效应单因子分析结果示全部36个条目在各自维度上的因子载荷为0.23～0.87(P<0.05),其中3个条目的载荷小于0.30。多因子分析结果χ²/df＝3.16,拟合优度指数(GFI)＝0.892,近似误差均方根(RMSEA)＝0.089,表明SF-36的各拟舍指数均在可被接受水平;证明SF-36的内部结构与其理论架构有很高的一致性。假体位置参数与SF-36各维度的相关系数都为正数,除GH外SF-36各维度与髋臼假体位相参数间相关系数均大于0.6,SF-36各维度与髋关节旋转中心体位相参数间高度相关,SF-36中活力(VT)、社会功能(SF)、情感职能(RE)及精神健康(MH)与股骨垂直偏距间相关系数大于0.7,SF-36中各维度与两侧股骨偏心距比例参数间相关系数均大于0.7,SF-36中SF、MH与外展肌力臂及重力力臂相参数间相关系数大于0.8,余者均大于0.7,SF-36各维度与股骨柄假体位相参数间相关系数在0.329～0.757之间,SF-36中生理功能(PF)、生理职能(RP)、社会功能(SF)与颈干角位相参数间相关系数在大于0.7。 结论SF-36量表信度、效度均较好,可用以评估THA患者生命质量。股骨颈骨折患者的生命质量在各个领域均明显低于正常人,THA术后均得到改善。SF-36各维度可全面反映患者心理、生理及社会生活状态下的生命质量。通过对假体位相参数与SF-36各维度间的相关系数分析认为：髋臼外展角及前倾角的适当范围分别为(45±5)°、(15±5)°;颈干角应控制在(125±10)°内;髋臼假体应置于髋臼解剖位置上,以健侧为参照重建旋转中心;术后患侧肢体长度较健侧缩短不宜超过10 mm;避免减小股骨偏心距、外展肌及重力力臂;尽量保持股骨柄中立位。     

髋关节表面置换术的近期疗效及其并发症分析

目的 探讨髋关节表面置换术(resurfacing arthroplasty of the hip,RSAH)的近期疗效及并发症.方法 回顾性分析行RSAH的患者26例(32髋),男14例,女12例;年龄30～62岁,平均46.8岁.术前诊断为髋臼发育不良9例(11髋),股骨头坏死7例(9髋),强直性脊柱炎3例(4髋),类风湿关节炎5例(6髋),骨关节炎1例(1髋),色素绒毛结节性滑膜炎1例(1髋).术前全部患者均行CT或MR检查观察髋臼与股骨头结构、囊性变、硬化、坏死位置和范围及骨缺损情况;术前、术后1个月、术后3个月及每半年拍摄髋关节正、侧位X线片,观察假体松动、移位及异位骨化等情况,临床疗效通过Harris评分评价.结果患者全部获得随访,平均随访2.1年(8个月～4.3年);Harris评分从术前平均(44.5±7.1)分提高到术后平均(94.3±5.2)分,其中优28髋(87.5%),良4髋(12.5%).并发症包括术中股神经损伤1例,异位骨化2例(3髋),臀中肌步态2髋,髋关节弹响2髋,下肢深静脉血栓1例,股骨颈缩窄1髋.无股骨颈骨折、感染、脱位及假体松动等其他并发症.结论 RSAH术后可获得满意的近期疗效,提高手术技术和严格掌握适应证可减少早期并发症发生.     

The hip in hereditary multiple exostoses

We defined the characteristics of dysplasia and coxa valga in hereditary multiple exostoses (HME) by radiological analysis of 24 hips in 12 patients. The degree and effect of the 'osteochondroma load' around the hip were quantified. We investigated the pathology of the labrum and the incidence of osteoarthritis and of malignant change in these patients. Coxa valga and dysplasia were common with a median neck-shaft angle of 156 degrees, a median centre-edge angle of 23 degrees and Sharp's acetabular angle of 44 degrees. There was overgrowth of the femoral neck with a significantly greater ratio of the neck/shaft diameter in HME than in the control hips (p < 0.05), as well as correlations between the proximal femoral and pelvic osteochondroma load (p < 0.05) and between the proximal femoral osteochondroma load and coxa valga (p < 0.01). Periacetabular osteochondromas are related to Sharp's angle as an index of dysplasia (p < 0.05), but not coxa valga. No correlation was found between dysplasia and coxa valga. These data suggest that HME may cause anomalies of the hip as a reflection of a generalised inherited defect, but also support the theory that osteochondromas may themselves precipitate some of the characteristic features of HME around the hip.     

The femoral head/neck offset and hip resurfacing

Because the femoral head/neck junction is preserved in hip resurfacing, patients may be at greater risk of impingement, leading to abnormal wear patterns and pain. We assessed femoral head/neck offset in 63 hips undergoing metal-on-metal hip resurfacing and in 56 hips presenting with non-arthritic pain secondary to femoroacetabular impingement. Most hips undergoing resurfacing (57%; 36) had an offset ratio or= 50.5 degrees. Most hips undergoing resurfacing have an abnormal femoral head/neck offset, which is best assessed in the sagittal plane.     

Anteversion of the acetabulum and femoral neck in early walking age patients with developmental dysplasia of the hip

Computed tomography measurements were made to quantify the relationship between the anteversion of the acetabulum and femoral neck in 27 early walking age patients (age range; 18-48 months) with developmental dysplasia of the hip. The centre-edge angle and acetabular index were measured in standard pelvis radiographs, and anteversion of acetabulum and femoral neck were measured by use of two-dimensional computed tomography in 25 complete dislocated, 19 subluxated and 10 unaffected hips (a total of 54 hips). The diagnosis of dysplasia, subluxation and complete dislocation of developmental hip dysplasia were determined radiographically using Ishida's criteria. There were statistically significant differences between the three groups for the centre-edge angle, the acetabular index, and acetabulum anteversion. There was no statistically significant difference between the three groups for femoral neck anteversion. The acetabular anteversion was found to be 13.4+/-2.8 degrees (mean+/-SD) in unaffected hips, 16.7+/-1.9 degrees in subluxated hips and 19.8+/-2.5 degrees in complete dislocated hips. There was statistically significant difference between the three groups, with a wide range of acetabular anteversion values noted in all groups (9-26 degrees ). The acetabular anteversion was increased on the dislocated side in each patient and we found no retroverted acetabulum. On the other hand there was no significant difference between the groups with regards to femoral neck anteversion. We conclude that confirming anteversion of the acetabulum and the femoral neck by two-dimensional computed tomography is needed in treatment planning of early walking age patients with developmental hip dysplasia.     

Biomechanics of the hip joint. I. A new model for the calculation of the forces in the hip joint]

After a short review of the theory of the forces acting in the human hip joint we develope a new model for the calculation of the forces R acting on the head of the supporting femur, of their direction phi and of the maximal pressure of the femoral head. The new concept is the determination of a fixed point A, the attachement of the resultant muscle force M at the pelvis, and the insertion T of this muscle force at the trochanter. After determination of this points in a single standard radiography of the pelvis and hips, the model calculate the resultant force R at the hip joint. The pressure in the articulation is calculated also by the same proceeding. The influence of the choice of the point A is discussed.