Comparison of a sliding hip screw with a trochanteric lateral support plate to an intramedullary hip screw for fixation of unstable intertrochanteric hip fractures: a cadaver study

BACKGROUND: The lateral trochanteric support plate (LSP) was developed to prevent excessive sliding of unstable intertrochanteric femur fractures fixed with a sliding hip screw (SHS). This study compared the fracture stability and screw sliding characteristics of unstable intertrochanteric femur fractures fixed with either an SHS and LSP or an Intramedullary Hip Screw (IMHS). METHODS: Six matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric femur fractures were stabilized with either an IMHS or a 135-degree SHS with an attached LSP. Inferior and lateral head displacements and lag screw sliding distances were measured for applied static loads of 750 N, before and after cycling. RESULTS: Four-part unstable intertrochanteric femur fractures showed comparable screw sliding characteristics and stability whether instrumented with an SHS and LSP or an IMHS. CONCLUSION: A sliding hip screw with an attached lateral support plate provides stability and ability to resist medial displacement of the femoral shaft similar to that seen with the IMHS.     

Helical blade versus sliding hip screw for treatment of unstable intertrochanteric hip fractures: a biomechanical evaluation

OBJECTIVE: To compare the fixation stability in the femoral head with sliding hip screw versus helical blade designs for unstable, intertrochanteric hip fractures. METHODS: A simulated, unstable intertrochanteric hip fracture was created in six pairs of cadaveric femurs. One of each pair was treated using an intramedullary nail with a sliding hip screw (ITST) for femoral head fixation and the other was treated with a nail with a helical blade (TFN). Each specimen was cyclically loaded with 750N vertical loads applied for 10, 100, 1000 and 10,000 cycles. Measurements for femoral head displacement, fracture fragment opening and sliding were made. Specimens were then loaded to failure. RESULTS: There was significantly more permanent inferior femoral head displacement in the ITST samples compared to the TFN samples after each cyclic loading (all p values<0.05). There was significantly more permanent fracture site opening and inferior displacement in the ITST group compared with the TFN group at 1000 and 10,000 cycles (p<0.05). Final loads to failure were not significantly different (p=0.51) between the two treatment groups. Nine specimens demonstrated fracture extension into the anteromedial cortex and subtrochanteric region and three specimens, which had an ITST implant, demonstrated a splitting fracture of the femoral head. CONCLUSION: This study demonstrated that fixation of the femoral head with a helical blade was biomechanically superior to fixation with a standard sliding hip screw in a cadaveric, unstable intertrochanteric hip fracture model.     

钽棒置入联合自体红骨髓移植治疗早期股骨头坏死的近期临床疗效

目的比较分析多孔钽棒置入和多孔钽棒置入联合自体红骨髓移植术治疗早期股骨头坏死的近期疗效。方法32例（38髋）早期股骨头坏死分为2组,其中钽棒置入（对照组）治疗16例（18髋）,钽棒置入联合自体红骨髓移植（实验组）治疗16例（20髋）。根据髋关节功能Harris评分比较2组临床疗效。结果术后3、6、12个月2组Harris评分均较术前明显提高,且实验组均较对照组高,差异有统计学意义（P〈0.05）。结论钽棒置入联合红骨髓移植治疗早期股骨头坏死较单纯钽棒置入可提高患者的髋关节功能,值得临床推广应用。     

Factors influencing postoperative movement in displaced femoral neck fractures: evaluation by conventional radiography and stereoradiography.

Postoperative movement in 46 displaced femoral neck fractures was studied using roentgen stereophotogrammetric analysis (RSA). Thirty-four fractures became stable, all within 1 year. Measurements on pre- and postreduction radiographs and scintimetry were performed to evaluate factors of importance in healing, redisplacement, and nonunion. Thirty-three fractures were treated with two hook-pins with (7 cases) or without (26 cases) a plate, and 13 were treated with two cancellous screws. Presence of intermediate fracture fragments and fixation with two screws implied increased movement of the femoral head center during the postoperative period. Remaining ad latus displacement on the anteroposterior or lateral view after reduction of more than 1 mm and low scintimetric uptake implied increased risk of redisplacement or pseudarthrosis. Increased displacement of the femoral head center during the first postoperative month was recorded in fractures that did not heal. The magnitude of the femoral head rotations did not differ between the implants, but smaller screw axis rotations were noted in fractures that subsequently healed. In most hips fixated with screws, the instant center of femoral head rotation went through the femoral head or neck, whereas hook-pin fixation more commonly was associated with screw axis position within or close to the trochanteric region, suggesting a more durable fixation in the femoral head of this device.     

Intramedullary versus extramedullar fixation of subtrochanteric fractures: A biomechanical study

We compared two different subtrochanteric fracture fixation techniques, an intramedullary hip screw system (IMHS) and an extramedullary dual sliding screw-plate system (MSP), to determine relative fixation stability. 6 matched pairs of osteosynthe-sized osteopenic cadaver femurs were axially loaded to 1000 N with concurrent, simulated abductor forces of 0%, 50% or 86% of the applied head force. The initial loading sequence was made with uniaxial dynamization-the lag screw of the MSP locked and distal locking of the IMHS nail. Femoral head displacement and medial femoral strain were measured for intact femur controls, after fixation of a 2-part reverse oblique subtrochanteric fracture and finally a 3-part reverse oblique subtrochanteric fracture with a lateral wedge defect. The samples were then loaded at 750 N for 10⁴ cycles with both devices uniaxially locked, followed by 10⁴ cycles with both devices fully biaxially dynamized (unlocked). For the 2-part subtrochanteric fracture pattern, both devices exhibited similar inferior displacements of the femoral head (average 2.0 mm) and medial femoral strain (-70% of intact). Increasing abductor forces decreased medial compressive strain but did not significantly affect head displacement. For the 3-part fracture model, the MSP demonstrated significantly less inferior displacement of the head (1.6 mm vs. 2.1 mm) and both devices demonstrated significantly decreased medial strain. After cycling, head displacement increased approximately 50% in both devices and medial strain increased slightly. After unlocking and cycling, the MSP group showed significant lateral displacement of the proximal fragment.

The IMHS and MSP devices provide similar stability for fixation of 2-part and 3-part reverse oblique subtrochanteric fractures. In a biaxially dynamized, 3-part reverse oblique fracture, displacement of the proximal fragment can occur with the MSP.     

Functional outcome and complications using the intramedullary hip screw for intertrochanteric fractures

We prospectively studied 110 consecutive patients with intertrochanteric hip fractures treated with the 130 degree angle, 10-mm short IMHS intramedullary hip screw (IMHS, Smith & Nephew, Richards, Memphis, TN). Surgery was performed within 36 hours from admission; all patients were mobilized immediately postoperatively. Fracture union, pre- and post-operative mobility status and complications were evaluated. Eighty patients were included in the postoperative evaluation for a mean followup of 14 (range, 9 to 25) months. Mortality was 19%. Union occurred in 79 fractures within 6 months from surgery; there was one case of screw cut-out and one case of deep venous thrombosis. Periprosthetic femoral shaft fractures were not observed. At the latest examination, the mean mobility score decreased from 8.4 +/- 1.6 to 7.1 +/- 2.1 (p = 0.0001); 26 patients (32%) fully achieved the preoperative mobility score and 54 patients (68%) achieved more than 90% of the preoperative mobility score. The IMHS intramedullary hip screw represents a reliable method for the treatment of patients with intertrochanteric hip fractures, and provides for early mobilization and rehabilitation of the patients with acceptable complications.     

A modified hip screw incorporating injected cement for the fixation of osteoporotic trochanteric fractures

OBJECTIVE: To evaluate a modified sliding hip screw for the fixation of trochanteric fractures that provides increased fixation strength in osteoporotic bones and allows for the safe intraoperative application of bone cement. DESIGN: Biomechanical cadaver study. MATERIALS: Unstable trochanteric fractures were simulated by osteotomy in nine pairs of cadaveric femurs and stabilized by a standard sliding hip screw randomly assigned to the left or right femur. The contralateral femur was stabilized with a newly designed hip screw, which was augmented with low-viscosity bone cement. MAIN OUTCOME MEASUREMENTS: Femoral bone mineral density was measured by dual x-ray absorptiometry and quantitative computed tomography. Fixation stability of the hip was assessed after dynamic loading by displacement measurement of the femoral head in a simulated one-leg stance configuration. RESULTS: Modification of the hip screw together with cement augmentation significantly (p < 0.05) increased the initial stability of the fracture fixation technique. The total displacement of the femoral head was reduced by 39 percent on average using cement augmentation in the modified screw compared with the standard sliding hip screw. The largest improvement in initial fixation stability was found for the most osteoporotic bones. CONCLUSIONS: This modified hip screw augmented with bone cement can significantly enhance the initial fixation stability of trochanteric fractures in osteoporotic femurs.     

Intramedullary hip screw versus sliding hip screw for unstable intertrochanteric femoral fractures in the elderly

We report a randomised, prospective study comparing a standard sliding hip screw and the intramedullary hip screw for the treatment of unstable intertrochanteric fractures in the elderly. One hundred and two patients were randomised on admission to two treatment groups. Fifty-two patients were treated with a compression hip screw (CHS), and fifty had intramedullary fixation with an intramedullary hip screw (IMHS). Patients were followed for 1 year and had a clinical and radiological review at 3, 6 and 12 months. The mean duration of operation and fluoroscopy screening time was significantly greater for insertion of the intramedullary hip screw. There was no difference between the groups with regard to transfusion requirements or time to mobilise after surgery. There were two technical complications in the CHS group and three in the IMHS group. There was no significant difference between the two groups in radiological or functional outcome at 12 months. It remains to be shown whether the theoretical advantages of intramedullary fixation of extracapsular hip fractures bring a significant improvement in eventual outcome.     

Using Naive Bayes Classifier to predict osteonecrosis of the femoral head with cannulated screw fixation

Predictive models permitting personalized prognostication for patients with cannulated screw fixation for the femoral neck fracture before operation are lacking. The objective of this study was to train, test, and cross-validate a Naive Bayes Classifier to predict the occurrence of postoperative osteonecrosis of cannulated screw fixation before the patient underwent the operation. The data for the classifier model were obtained from a ambispective cohort of 120 patients who had undergone closed reduction and cannulated screw fixation from January 2011 to June 2013. Three spatial displaced parameters of femoral neck: displacement of centre of femoral head, displacement of deepest of femoral head foveae and rotational displacement were measured from preoperative CT scans using a 3-dimensional software. The Naive Bayes Classifier was modelled with age, gender, side of fractures, mechanism of injury, preoperative traction, Pauwels angle and the three spatial parameters. After modelling, the ten-fold cross-validation method was used in this study to validate its performance. The ten-fold cross-validation method uses the whole dataset to be trained and tested by the given algorithm. Two of the three spatial parameters of femoral neck (displacement of center of femoral head and rotational displacement) were included successfully in the final Naive Bayes Classifier. The Classifier achieved good performance of the accuracy (74.4%), sensitivity (74.2%), specificity (75%), positive predictive value (92%), negative predictive value (42.9%) and AUC (0.746). We showed that the Naive Bayes Classifier have the potential utility to be used to predict the osteonecrosis of femoral head within 5 years after surgery. Although this study population was restricted to patients treated with cannulated screws fixation, Bayesian-derived models may be developed for application to patients with other surgical procedures at risk of osteonecrosis.     

内固定物尖端与股骨头边缘安全距离的几何学探讨

目的 通过几何学模型探讨内固定物尖端与股骨头边缘的安全距离,以避免内固定物穿出股骨头.方法 把股骨头作为一个球体处理,正、侧位投影所得为两个平面圆形影像.平面圆形影像所代表的空间结构为两个互相垂直的圆柱体,两者的公共部分即为正、侧位影像所代表的空间区域.分析股骨头的正、侧位投影所得的二维影像与其三维空间结构的几何关系,通过两者立体结构及体积的比较,计算为确保内固定物位于股骨头内所要求的内固定物尖端与股骨头边缘的安全距离.结果 股骨头的二维正、侧位影像所构成的空间结构为一个外切于股骨头球体的牟合方盖,其与股骨头球体的体积比为4:π.正、侧位X线影像中内固定物尖端均位于股骨头内的情况下,其实际上穿出股骨头的危险性约为21.5%.为了降低内固定物穿出股骨头的危险性,必须使牟合方盖的体积变小,即内固定物的尖端距股骨头边缘有一定的距离.当牟合方盖小到恰好内切于球体时,内固定物穿出股骨头的危险性降为零.此时通过几何学计算可知X线影像上内固定物尖端与股骨头中心的距离约为股骨头半径的0.71倍.即当X线影像上股骨头直径为5 cm时,内固定物尖端与股骨头边缘的距离约为0.7 cm.结论 为确保内固定物位于股骨头内,X线影像上内固定物尖端与股骨头中心的距离应小于股骨头半径的0.71倍.即当正、侧位X线影像上股骨头直径为5 cm时,内固定物尖端与股骨头边缘的安全距离应>0.7 cm.     

Surgical treatment of intertrochanteric hip fractures with associated femoral neck fractures using a sliding hip screw

OBJECTIVE: The purpose of this study was to report the results of surgical treatment of a subset of intertrochanteric fractures with posteromedial comminution and extension of the fracture line into the femoral neck using a sliding hip screw. DESIGN: Retrospective review. SETTING: Level I county trauma center. PATIENTS: Twenty-nine fractures (8%) with this pattern were identified from 381 intertrochanteric hip fractures treated at a single institution over a 10-year period. Nine patients were excluded (2 died, 7 had incomplete radiographic follow-up), leaving 20 patients for assessment. INTERVENTION: All fractures were treated with a sliding hip screw. MAIN OUTCOME MEASUREMENTS: Radiographs at a mean follow-up of 17 months were recorded as demonstrating: 1) fixation failure; 2) fracture union; or 3) fracture nonunion. The tip-apex distance, amount of lag screw collapse, screw position in the femoral head, and adequacy of reduction were determined. RESULTS: Treatment failed according to these radiographic measures in 5 of 20 (25%) fractures. Failures included fracture nonunion (1 case), lag screw cutout (2 cases), and combined nonunion/lag screw cutout (2 cases). All 5 failures had complete collapse of the lag screw, whereas 4 of the 15 successfully treated fractures had complete collapse. The amount of collapse was significantly greater for the treatment failures (mean, 38 mm) than in the successfully treated hips (mean, 20 mm). There was no significant association between treatment success or failure and tip-apex distance, lag screw position, and adequacy of reduction. CONCLUSION: We conclude that intertrochanteric hip fractures with associated femoral neck fractures should not be managed with a standard sliding hip screw.     

"Y"型软骨未闭合儿童股骨颈骨折术后股骨近端骺板早闭的风险因素分析

目的探讨"Y"型软骨未闭合儿童股骨颈骨折术后股骨近端骺板早闭(premature proximal femur physeal closure,PPC)的风险因素。方法回顾性分析2010年3月至2017年5月采用手术治疗的106例"Y"型软骨未闭合股骨颈骨折患儿资料,记录患儿的年龄、性别、侧别、受伤机制、骨折分型、移位程度、手术时机、固定方式、有无过骺板固定、复位方式、复位质量和末次随访时有无股骨头坏死等可疑风险因素。术后6~12个月通过X线片评估有无PPC的发生。结果106例患儿均得到随访,随访时间(20.4±13.3)个月(范围6~86个月)。其中39例患儿股骨颈骨折术后发生PPC,发生率为36.8%(39/106)。发生PPC的患儿39例,男25例,女14例;年龄(9.7±3.6)岁(范围3~15岁);左侧23例,右侧16例;交通伤5例,高处坠落伤21例,运动伤12例,其他类型损伤1例;DelbetⅠ型2例,Ⅱ型26例,Ⅲ型11例;移位程度Ⅱ度26例,Ⅲ度13例;受伤至手术时间(3.3±2.8)d(范围1~14 d);克氏针固定2例,螺钉固定35例,钢板固定2例;过骺板固定2例,未过骺板固定37例;闭合复位15例,开放复位24例;解剖复位14例,可接受复位24例,不可接受复位1例;末次随访时24例出现股骨头坏死,余15例无股骨头坏死。统计学分析显示,有PPC的患儿年龄(t=3.875,P<0.001)、移位程度(Z=-2.118,P=0.034)和股骨头坏死的发生率(χ^2=42.280,P<0.001)均大于无PPC的患儿,差异均有统计学意义;其余各因素两者比较差异均无统计学意义。Logistic回归分析结果显示,年龄(OR=1.288,P=0.011)和股骨头坏死(OR=40.336,P<0.001)是儿童股骨颈骨折术后发生PPC的独立风险因素。ROC曲线分析提示年龄>10岁会增加PPC的风险。年龄≥10岁的患儿PPC发生率(63.6%,21/33)高于年龄<10岁的患儿(24.7%,18/73)(χ^2=14.848,P<0.001)。结论年龄≥10岁和股骨头坏死是"Y"型软骨未闭合儿童股骨颈骨折术后股骨近端骺板早闭的风险因素。     

股骨颈骨折内固定术后股骨头坏死的相关因素分析及生活质量评价

目的:探讨年轻患者股骨颈骨折内固定术后发生股骨头坏死的危险因素,描述股骨头存活患者的生活质量,量化其预测因素。方法:选取2013年1月至2016年12月采用闭合复位空心钉内固定手术治疗的股骨颈骨折患者172例(174髋)进行回顾性分析,总结患者的一般资料包括年龄、性别、体重指数、创伤机制、创伤-手术间隔时间、创伤发生季节和内固定物是否取出,影像学资料包括骨折Garden分型、Pauwel分型、股骨头后倾角度、术后骨折复位、螺钉分布情况。进行单因素分析及多因素Logistic回归分析,探讨股骨头坏死及内固定失败的危险因素。对上述内固定术后股骨头存活的患者进行随访,通过SF-36健康调查简表评估患者的生活质量,髋关节功能Harris评分评估患髋关节功能,并通过多重线性回归分析探讨股骨颈骨折术后患者生活质量的预测因素。结果:172例(174髋)患者纳入研究,共29例(16.67%)患者发生股骨头坏死。股骨头坏死多因素Logistic回归分析中有显著差异的变量是复位质量(OR=0.126,P=0.027)和后倾角(OR=4.380,P=0.010)。股骨头存活136例患者(137髋)纳入生活质量调查,Harris评分90.14±7.92,其中优96髋(70.07%),良28髋(20.44%),中13髋(9.49%),差0髋。SF-36评分中生理健康得分为46.12±9.12,心理健康得分为50.21±3.97,两者不呈线性相关(P0.05),多重线性回归分析中,与生理健康得分相关有显著差异的变量是复位质量与后倾角度,与心理健康得分相关有显著差异的变量是骨折是否移位与创伤机制。结论:复位质量位不佳和后倾角15°是并发股骨头坏死的危险因素。股骨颈骨折术后患者髋关节功能及心理健康得分恢复良好,但生理健康得分不能恢复到正常人群平均水平,复位质量与后倾角度可作为生理健康得分预测因素,骨折是否移位与创伤机制可作为心理健康得分的预测因素。     

国产可吸收钉治疗股骨头骨折的实验研究及临床评价

目的: 观察国产可吸收钉关节内植入后对周围组织的影响, 评价其在治疗股骨头骨折中的临床疗效。方法: 新西兰兔 6只于两侧膝关节内分别植入可吸收钉及金属钉; 4、8、12周后取标本, 行大体及组织学观察。临床 45例股骨头骨折患者采用国产可吸收钉固定。结果: 可吸收钉植入组, 仅表现组织对异物的正常反应; 金属钉组见关节软骨有明显的机械性损伤。45例患者, 随访 12~28个月, 优良率为 93%, 未发现不良反应。结论: 国产可吸收钉是治疗股骨头骨折理想的内固定物。     

亚洲型髋关节髓内钉系统治疗股骨转子间骨折

目的分析亚洲型髋关节髓内钉系统（Asian intramedullary hip system,ASIAN IMHS）治疗股骨转子间骨折的临床疗效。方法2006年1月至2008年1月,应用ASIAN IMHS治疗34例股骨转子间骨折,骨折按AO／ASIF分型,31—A1型10例,31-A2型13例,31-A3型11例。结果32例患者获得6～18个月随访。骨折全部愈合,愈合时间为11～23周,平均14．5周,尖顶距平均值24mm,无术中并发症,无感染、深静脉血栓、髓内钉断裂、股骨干骨折、拉力螺钉松动断裂及切出股骨头、髋内翻畸形等并发症发生。结论ASIAN IMHS基于亚洲人解剖特点设计,治疗股骨转子间骨折具有操作步骤简单、创伤小、骨折同定确实、并发症少及患者町早期功能锻炼等优点,值得推荐。术中C臂正侧位测量克氏针尾端至关节面的距离之和对预防拉力螺钉切出股骨头有重要意义。     

Femoral neck fracture: sliding screw plate versus sliding nail plate--a randomized trial

In a randomized trial 49 patients with fracture of the neck of the femur and an age of less than 70 years or a high level of physical activity were allocated to treatment with a sliding screw plate or a sliding nail plate fixation. The patients were followed for 2-5 years. At follow-up the union rate was found to be 86.2 per cent of the fractures in the screw plate group and 73.7 per cent in the nail plate group (P less than 0.3). Necrosis of the femoral head was encountered in respectively 10 and 21 per cent. Hip replacement was necessary in respectively 23.3 and 31.6 per cent. The nail slid out of the femoral head, resulting in recurrence of the fracture's displacement in three fractures with a sliding nail plate, and in none with a sliding screw plate (P = 0.053). Secondary loss of the femoral neck's angle was more frequently seen in the sliding nail plate group (P less than 0.01). In conclusion, the sliding screw plate gives better fixation of fractures of the neck of the femur and was followed by a lower frequency of reoperation than after an unthreaded device.     

Biomechanical stability of single-screw versus two-screw fixation of an unstable slipped capital femoral epiphysis model: effect of screw position in the femoral neck

PURPOSE: To biomechanically evaluate single screw and varying 2 screw fixations for an unstable slipped capital femoral epiphysis (SCFE) model using physiologically relevant loading. STUDY DESIGN: In vitro biomechanical study. METHODS: Twenty-four immature porcine proximal femurs were prepared to simulate a mild-to-moderate unstable SCFE. The femurs were randomized into 4 fixation groups: single screw, 2 screws horizontally placed, 2 screws vertically placed, and 2 oblique screws. Biomechanical testing determined maximum load to failure (N), load (N) at 2, 4, 6, and 8 mm of femoral head displacement, and stiffness (newtons per millimeter) for each group. RESULTS: No significant differences were found among the 3 different 2 screw configurations. The 2 screw constructs were 66% stiffer and 66% stronger than the single screw construct. In addition, whereas there was no difference at 2 mm of femoral head displacement, each subsequent displacement (4, 6, and 8 mm) demonstrated significantly higher failure loads when 2 screws were used for stabilization. CONCLUSIONS: Slipped capital femoral epiphysis stabilization with 2 screws leads to increased stability over single screw fixation; however, none of the 3 configurations/placement patterns of the 2 screw constructs seemed to be superior in fixation stability. CLINICAL RELEVANCE: These data support the use of a 2 screw construct in acute/unstable SCFE fixation. The biomechanical benefit of 2 screws needs to be considered in the face of greater potential for inadvertent penetration into the joint with an increased number of screws.     

Die Sicherung der Hüftkopfepiphyse mit der Gleitschraube bei Epiphyseolysis capitis femoris juvenilis

OBJECTIVE: In situ fixation of the proximal femoral epiphysis to prevent further dislocation while maintaining the potential for longitudinal growth by insertion of a central gliding screw. Prevention of secondary coxarthrosis. INDICATIONS: Incipient and imminent slipped capital femoral epiphysis in children with a displacement angle of < 30 degrees in the axial view (ET' < 30 degrees ) and prophylactic treatment of the contralateral side. CONTRAINDICATIONS: Allergies to implant materials. SURGICAL TECHNIQUE: A Kirschner wire is inserted through a lateral proximal approach in the femur into the center of the displaced epiphysis at a right angle to its base. Overdrilling of the wire, thread tapping in the cancellous bone, insertion of the cannulated gliding screw with washer. The screw threads lie only in the epiphysis. The unthreaded part of the screw bridges the growth plate. The screw is allowed to protrude by about 2.5 cm to prevent an epiphyseodesis effect. POSTOPERATIVE MANAGEMENT: Partial weight bearing of the affected extremity up to 10 kg body weight for 6 weeks. Thrombosis prophylaxis during convalescence only for adolescents with signs of puberty (menarche/pubarche). Restriction on sports activities for 3 months. Follow-ups: clinical and radiologic examinations at 3 months postoperatively, then clinical examination every 6 months and radiologic assessment annually (possibly earlier, if there is a growth spurt). The gliding screw is removed when growth is completed. RESULTS: 63 hips (34 prophylactically and 29 therapeutically) were stabilized with the gliding screw. Clinically, the prophylactically stabilized hips showed excellent outcomes; of the therapeutically stabilized hips, the results were 19 excellent, seven good, two satisfactory, and one poor. Differences in leg length were seen in five cases, whereby the average value was 0.3 cm (0-1 cm). Chondrolysis or femoral head necrosis was not observed. Screw revision was necessary in 22 cases because contact between the screw head and the cortex would have prevented continued longitudinal growth (unintentional epiphyseodesis).     

Ectopic bone formation around the poly-<Emphasis Type="SmallCaps">l</Emphasis>-lactide screw head in rotational acetabular osteotomy for hip dysplasia

Ectopic bone formation around the poly-l-lactide (PLLA) screw head in eccentric rotational acetabular osteotomy for hip dysplasia was investigated. A total of 174 hips in 165 patients with hip dysplasia were consecutively treated with eccentric rotational acetabular osteotomy. Average age at the time of operation was 37 years. Acetabular fragments of 123 patients (132 hips) were fixed by Kirschner wires (K-wire group), and 42 hips in 42 patients were fixed with PLLA screws (PLLA group). There was no statistically significant difference between the backgrounds of the two groups. All patients were evaluated clinically and radiologically. In the K-wire group, ectopic bone formation of class 2 was observed in only 1 hip. In the PLLA group, ectopic bone formation of class 3 in 1 hip and class 2 in 3 hips was observed around the screw head 3 months postoperatively, and all hips but 1 showed class 2 at final follow-up. One hip with class 3 at 1 year developed marked reduction of range of motion, and this patient complained of moderate hip pain and stiffness. PLLA screws significantly enhanced ectopic bone formation around the screw head in eccentric rotational acetabular osteotomy.     

Effect of femoral head diameter and operative approach on risk of dislocation after primary total hip arthroplasty

BACKGROUND: It has been postulated that use of a larger femoral head could reduce the risk of dislocation after total hip arthroplasty, but only limited clinical data have been presented as proof of this hypothesis. METHODS: From 1969 to 1999, 21,047 primary total hip arthroplasties with varying femoral head sizes were performed at one institution. Patients routinely were followed at defined intervals and were specifically queried about dislocation. The operative approach was anterolateral in 9155 arthroplasties, posterolateral in 3646, and transtrochanteric in 8246. The femoral head diameter was 22 mm in 8691 of the procedures, 28 mm in 8797, and 32 mm in 3559. RESULTS: One or more dislocations occurred in 868 of the 21,047 hips. The cumulative risk of first-time dislocation was 2.2% at one year, 3.0% at five years, 3.8% at ten years, and 6.0% at twenty years. The cumulative ten-year rate of dislocation was 3.1% following anterolateral approaches, 3.4% following transtrochanteric approaches, and 6.9% following posterolateral approaches. The cumulative ten-year rate of dislocation was 3.8% for 22-mm-diameter femoral heads, 3.0% for 28-mm heads, and 2.4% for 32-mm heads in hips treated with an anterolateral approach; 3.5% for 22-mm heads, 3.5% for 28-mm heads, and 2.8% for 32-mm heads in hips treated with a transtrochanteric approach; and 12.1% for 22-mm heads, 6.9% for 28-mm heads, and 3.8% for 32-mm heads in hips treated with a posterolateral approach. Multivariate analysis showed the relative risk of dislocation to be 1.7 for 22-mm compared with 32-mm heads and 1.3 for 28-mm compared with 32-mm heads. CONCLUSIONS: In total hip arthroplasty, a larger femoral head diameter was associated with a lower long-term cumulative risk of dislocation. The femoral head diameter had an effect in association with all operative approaches, but the effect was greatest in association with the posterolateral approach.