Vibration-assisted bone-graft compaction in impaction bone grafting of the femur

The complications of impaction bone grafting in revision hip replacement includes fracture of the femur and subsidence of the prosthesis. In this in vitro study we aimed to investigate whether the use of vibration, combined with a perforated tamp during the compaction of morsellised allograft would reduce peak loads and hoop strains in the femur as a surrogate marker of the risk of fracture and whether it would also improve graft compaction and prosthetic stability. We found that the peak loads and hoop strains transmitted to the femoral cortex during graft compaction and subsidence of the stem in subsequent mechanical testing were reduced. This innovative technique has the potential to reduce the risk of intra-operative fracture and to improve graft compaction and therefore prosthetic stability.     

旋股外多条血管束移植治疗青壮年移位型股骨颈骨折

青壮年移位型股骨颈骨折往往并发发骨不连及股骨头坏死。采用旋股外多条血管束移植，加压螺钉内固定，配合中药活血化瘀，治疗ＧａｒｄｅｎⅣ型股骨颈骨折，与带肌蒂骨瓣，带血管蒂骨瓣移植加螺钉内固定及单纯加压螺钉内固定比较，疗效优越。     

Superelastic cage implantation: a new technique for treating osteonecrosis of the femoral head with mid-term follow-ups

We developed a device for the treatment of Ficat and Arlet stage II and III osteonecrosis of the femoral head. This device, which we named the “super-elastic cage,” was designed to provide mechanical support for the necrotic weight-bearing area of the femoral head to prevent its collapse. The cage was used in combination with surgical removal of necrotic bone, insertion of vascularized pedical bone graft, or impacted autologous cancellous bone graft. A total of 93 hips in 62 patients at Ficat stage II to III were included in a 8-year study. Implantations were performed by 2 different approaches: Smith-Peterson approach and minimal invasive approach by the lateral side of great trochanter. The follow-up period was between 72 and 107 months. Of the femoral heads in this study, 82.7% survived. The superelastic cage implantation technique may offer an alternative treatment to the early and middle stages of osteonecrosis of the femoral head.     

Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty. A human cadaveric mechanical study

Background and purpose

The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies.

Methods

Using a standardized impaction grafting technique with modifications, an initial group of 17 femurs underwent complete destructive impaction testing, allowing sequentially increased, controlled impaction forces to be applied until femoral fracture occurred. A second group of 8 femurs underwent impaction bone grafting at constant force, at an impaction frequency of 1 Hz or 10 Hz. An Exeter stem was cemented into the neomedullary canals. These constructs underwent subsidence testing simulating the first 2 months of postoperative weight bearing.

Results

No femurs fractured below an impaction force of 0.5 kN. 15/17 of the femurs fractured at or above 1.6 kN of applied force. In the second group of 8 femurs, all of which underwent femoral impaction grafting at 1.6 kN, there was no correlation between implant subsidence and frequency of impaction. Average subsidence was 3.2 (1–9) mm.

Interpretation

It is possible to calculate a force below which no fracture occurs in the embalmed human femur undergoing impaction grafting. Higher impaction frequency at constant force did not reduce rates of implant subsidence in this experiment.With the increasing success of acetabular impaction bone grafting in dealing with loss of acetabular bone stock, attempts were made to use the technique to fill femoral bone defects in revision hip arthroplasty. The results of femoral impaction grafting have been satisfactory. In a recent review of over 1,000 femoral impaction graftings, Ornstein et al. (2009) reported 15-year implant survival rates of 94%, with minimal difference in implant survivorship between low- and high-volume units, suggesting that the technique of femoral impaction grafting appears to be, “reliable, can be learned rapidly, and produces a predictably low incidence of aseptic loosening.”Despite these results, however, there is still concern regarding the high rate of complications of femoral impaction grafting, the main complications being operative or perioperative femoral fracture and implant subsidence. Fracture rates of up to 16% have been reported (Masterson et al. 1997, Leopold et al. 1999, Pekkarinen et al. 2000). High rates of implant subsidence have also been described (Eldridge et al. 1997, Masterson et al. 1997), which may be due to inadequate impaction of the morselized bone graft. Thus, increasing the impaction force will ensure improved graft stability but will increase the risk of femoral fracture.In a preliminary study on sow femurs, Flannery et al. (2010) achieved a stable construct without fracture. A stable construct was defined as a femur that underwent impaction bone grafting at sub-threshold force, with a cemented Exeter stem that did not undergo massive early subsidence (10 mm) on initial subsidence testing simulating the first 2 postoperative months of weight bearing. The authors were unable to find any correlation between threshold force, bone mineral density, cortex-to-canal ratio, or cortical thickness in impaction bone grafting in the adult sow femur.In this study, we applied the experimental protocol of Flannery et al. (2010) to a sample of adult human femurs and investigated the above associations—but with the addition of measurement of cortex-to-canal ratios on standardized pretesting plain radiographs.The compaction of the bone graft may also be dependent on the frequency of impaction. In a laboratory study on impacted pig bone, Marck Van Liefland (2006) reported that “high-frequency impaction achieved high compaction at low load.” in a pot of morselized pig bone graft. While high compaction was achieved, the author did not state how far the graft had compressed. “Compared to traditional impaction, the same amount of compaction was achieved at 10–20% of the load. Inversely, compaction almost doubled at the same load.” Thus, prevention of massive early subsidence of the femoral component may also be dependent on the frequency of impaction to obtain adequate compaction, possibly permitting lower forces to be applied at higher frequencies and possibly reducing fracture risk.A final subset of femurs then underwent impaction bone grafting at set impaction force. This was followed by subsidence testing with a cemented Exeter stem, half at an impaction frequency of 1 Hz and the other half at an impaction frequency of 10 Hz.     

卵巢切除大鼠皮质骨氨基多糖和非胶原蛋白变化与矿盐丢失

本实验目的是观察卵巢切除（ＯＶＸ）大鼠皮质骨矿盐变化特点，研究其变化机理。选用ＳＤ．两月龄大鼠，摘除双侧卵巢，实验期６０天。观察了ＯＶＸ大鼠股骨干近、中和远１／３段矿盐含量的变化及股骨干近１／３段骨质中氨基多糖（ＧＡＧ）、白蛋白和骨钙素（ＢＧＰ）含量的变化。研究结果显示：ＯＶＸ６０天大鼠股骨干仅近１／３段矿盐含量显著降低，中和远１／３段矿盐含量无明显改变。股骨干近１／３段骨质中ＧＡＧ和ＢＧＰ含量显著增加，白蛋白含显显著降低。结果表明ＯＶＸ６０天大鼠股骨干近１／３段矿盐丢失与局部骨质内ＧＡＧ含量增加，白蛋白含量和ＢＧＰ质量降低有关。     

Prefabrication of periosteal graft alone or with oxidised cellulose: an experimental study

The purpose of this study was to evaluate the feasibility of prefabrication of periosteal grafts, alone or with oxidised cellulose (surgicel), which was an osteoinductive material using femoral vasculature. Fifteen white New Zealand rabbits were used in both femoral regions (30 grafts), and randomly divided into three groups including five rabbits (10 grafts): the control group, the periosteal graft group, and the periosteal graft+surgicel group. A periosteal graft, 30 x 40 mm in size, was obtained from the calvarium of each rabbit. The periosteal graft taken was divided into two equal parts, 20 x 30 mm. All these periosteal grafts were sutured in the shape of tube. In all rabbits, femoral vasculature and periosteal tube was Included in a silicone tube. Additionally, in the control group, femoral vasculature was cut above and below the silicone tube, whereas in the periosteal graft+surgicel group, surgicel was added to the periosteal graft. The results were evaluated macroscopically and histopathologically in the second (two rabbits for each group - 4 grafts) and fourth week (3 rabbits for each group - 6 grafts). In the second week, In all three groups, while no osteoid tissue that indicated osteogenesis developed, it was seen that inflammation and increased vascularity occurred. Surgicel was observed to be absorbed in the periosteal graft+surgicel group. In the fourth week, fibrotic tissue was developed whereas inflammatory tissue disappeared; any osteoid tissue or lamellar bone was not accompanied in all three groups. In conclusion, we do not believe that periosteum was able to survive as a graft, and we found that neovascularization occurred too slowly to preserve the bone forming qualities of the periosteum. We suggested that it could not be prefabricated, being taken away from its donor site although surgicel was used as a stimulating material.     

Comparative study of iliac crest and subchondral femoral bone in osteoarthritic patients.

This is a study of trabecular bone changes in selected regions of the femoral head. Iliac crest bone from osteoarthritic (OA) and control groups is compared to the bone from regions in the femoral head. The regions are the subchondral principal compressive and tensile areas. These areas of highest and lowest stress undergo dramatic change with OA. The compressive region has total cartilage loss and eburnation. Bone histomorphometry was done on undecalcified tissue sections stained by the von Kossa silver method and counter-stained with haematoxylin and eosin. Iliac crest histomorphometry is similar for the OA and control groups. The femoral trabecular structure in the stress regions changes in opposing directions with OA. In the compressive region the structural variables (BV/TV and BS/TV) increase [corrected], and in the tensile region decrease. Femoral bone turnover indices (OV/TV, OS/BS, and ES/BS) are no different, but femoral bone structure is different from that of the iliac crest. In OA patients there is no significant increase in iliac crest trabecular bone volume. The iliac crest is not useful to assess the bony changes in femoral OA.     

The use of OP-1 in femoral impaction grafting in a sheep model.

The aim of this pilot study was to examine bone graft incorporation in femurs impacted with allograft bone alone (control group) or with allograft containing the bone morphogenetic protein OP-1 (BMP-7) (OP-1 group) in a sheep model of cemented hemiarthroplasty. Two sheep in each group were sacrificed at 6, 18 and 26 weeks. Successful bone graft incorporation was evident in both groups by six weeks but in the OP-1 group, there had been more extensive resorption of the graft. There was one case of excessive stem subsidence in the OP-1 group at six weeks. By 18 weeks, there was remodelling and trabeculation of the new bone in the OP-1 group, but this appeared less advanced in the control group. By 26 weeks, there was remodelling of bone in the graft bed. The results of this small study suggest that OP-1 promotes initial graft resorption, thus hastening bone graft incorporation and remodelling in femoral impaction grafting. The one case of stem subsidence may be associated with the early resorption seen in the OP-1 group and reinforces the need for further studies, examining dose response and using precise measures of stem movement, before this BMP is used in femoral impaction grafting at revision hip arthroplasty.     

Effect of vibration on the shear strength of impacted bone graft in revision hip surgery

We developed a method of applying vibration to the impaction bone grafting process and assessed its effect on the mechanical properties of the impacted graft. Washed morsellised bovine femoral heads were impacted into shear test rings. A range of frequencies of vibration was tested, as measured using an accelerometer housed in a vibration chamber. Each shear test was repeated at four different normal loads to generate stress-strain curves. The Mohr-Coulomb failure envelope from which shear strength and interlocking values are derived was plotted for each test. The experiments were repeated with the addition of blood in order to replicate a saturated environment. Graft impacted with the addition of vibration at all frequencies showed improved shear strength when compared with impaction without vibration, with 60 Hz giving the largest effect. Under saturated conditions the addition of vibration was detrimental to the shear strength of the aggregate. The civil-engineering principles of particulate settlement and interlocking also apply to impaction bone grafting. Although previous studies have shown that vibration may be beneficial in impaction bone grafting on the femoral side, our study suggests that the same is not true in acetabular revision.     

A preclinical study of stem subsidence and graft incorporation after femoral impaction grafting using porous hydroxyapatite as a bone graft extender

This preclinical in vivo screening study compared bone graft incorporation and stem subsidence in cemented hemiarthroplasty after femoral impaction bone grafting with either morselized allograft bone (n = 5, control group) or a 1:1 mix of allograft and porous hydroxyapatite ceramics (HA) granules (n = 5, HA group). At 14 weeks, there was excellent bone graft incorporation by bone, and the stems were well fixed in both groups. The median subsidence at the cement-bone interface, measured using radiostereometric analysis, was 0.14 and 0.93 mm in the control and HA groups, respectively. The comparable histologic results between groups and good stem fixation in this study support the conduct of a larger scale investigation of the use of porous HA in femoral impaction bone grafting at revision hip arthroplasty.     

Age-Related Cancellous Bone Loss in the Proximal Femur of Caucasian Females

The purpose of this investigation was to directly define the age-related intrafemoral variations in cancellous bone density, bone mineralization and rate of bone loss in a cadaveric population of Caucasian female femoral necks and trochanters. Forty-three Caucasian female femora were obtained and divided into premenopausal, postmenopausal and elderly age groups. The neck and trochanter were removed, and cores of cancellous bone were taken from the superior, middle and inferior regions; volume fraction and ash fraction were determined for each core. The cancellous bone volume fraction of the neck was significantly greater than that of the trochanter, as was that of the inferior region of the neck compared with the superior and middle regions at all age groups (p<0.05). The mean neck/trochanter and neck inferior/superior volume fraction ratios did not change with age; however, the variance increased with age (p<0.001). This increasing variability with age suggests that there may be a subpopulation of individuals within the elderly Caucasian population with a significantly different intrafemoral bone density distribution than was present prior to menopause. This study identified no mineralization changes with age in the cancellous bone of the proximal femur (p>0.05). The influence of increased neck/trochanter and neck inferior/superior ratios on femoral neck integrity and fracture prediction is of interest and requires further investigation. Received: 8 April 1999 / Accepted: 18 October 1999     

Contributions of femoral fixation methods to the stiffness of anterior cruciate ligament replacements at implantation.

One purpose of this study was to determine the stiffness of three femoral fixation methods used commonly in anterior cruciate ligament (ACL) reconstruction to secure a double-looped semitendinosus and gracilis (DLSTG) graft and then assess how the stiffness of these methods affects the stiffness of the young human femur-fixation method-graft complex at the time of reconstruction. A second purpose was to define principles for adjusting the stiffness of the ACL replacement (defined as the femoral fixation method plus DLSTG graft plus tibial fixation method) to match that of the native ACL. The stiffness of a DLSTG graft and the stiffness of the femur-fixation method-DLSTG graft complex for three endoscopic fixation methods were measured. Fixations of the DLSTG graft to a button, anchor, and post, both with and without compaction of bone, were tested in young, human femur. The stiffness of each fixation was calculated by modeling the DLSTG graft and fixation method as a series of springs. The stiffness of the DLSTG graft averaged 954+/-292 N/mm. The stiffness of the DLSTG graft-fixation complex was lowered fourfold to 40-fold by adding fixation. The method of fixation determined the reduction in stiffness. The stiffness of the femur-button-DLSTG graft complex averaged 23+/-2 N/mm, the femur-anchor-DLSTG graft complex averaged 25+/-3 N/mm, and the femur-post with bone graft-DLSTG graft complex averaged 225+/-23 N/mm (P = .0001). The knot in the suture loop was the least stiff component and determined the stiffness when the DLSTG graft was fixed with both the button and anchor. Compaction of bone significantly increased stiffness by an average of 41+/-14 N/mm (P = .027). Because the stiffness of femoral fixation methods are 4 to 40 times less than the stiffness of the graft, increasing the stiffness of an ACL replacement would be best achieved by selecting fixation methods with higher stiffness and not by either shortening the graft or increasing the cross-sectional area of the graft.     

Different patterns of cartilage wear in medial and lateral gonarthrosis

We studied the morphologic changes of cartilage wear on the resected parts of the joint in 42 knees operated on with a total knee prosthesis. The medial and lateral compartments were divided into 6 equal regions on both the tibial and femoral sides. The amount of cartilage/bone destruction was classified into 4 grades in each region. In medial and lateral arthrosis, maximal wear was found in the middle of the joint, but it was more marked in the lateral group. In the medial group, wear was greater in the anterior regions. In the lateral group, we found more wear in the posterior regions. We ascribed these findings to different anterior/posterior translations of the medial and lateral condyles during flexion/extension of the knee joint.     

旋股外动脉升支血管蒂髂骨瓣移植治疗成人股骨头坏死的临床分析

目的观察旋股外动脉升支血管蒂髂骨瓣移植治疗Ⅱ、Ⅲ期股骨头坏死效果。方法本组收集65例（71髋）Ⅱ、Ⅲ期股骨头坏死的患者,采用带旋股外动脉升支血管蒂髂骨瓣移植的手术治疗,观察其疗效。结果本组于术后48～72个月随访,优良率为87.69%。股骨头坏死Ⅱ期患者的优良率（97.22）明显高于Ⅲ期患者（75.86%）。结论带旋股外动脉升支血管蒂髂骨瓣移植为治疗Ⅱ、Ⅲ期股骨头坏死的有效方法,尤其对Ⅱ期股骨头坏死的疗效更加明显,临床应推广应用。     

青年与老年股骨距的显微结构特征及其临床意义

目的 观察青年、老年股骨距的显微结构。方法 取１８～３０岁青年男性及６０岁以上老年（性别不详）冷藏尸体股骨上段各６根,ＣＴ扫描后,由股骨距起点开始向远端做连续三层股骨截片,每层厚５ｍｍ,对股骨截片先做Ｘ线摄片,然后分别对其中的股骨距进行光镜和扫描电镜观察。结果 在横截面上股骨距分为三个区域：股骨距近端为皮质骨,附着于股骨内侧皮质,主要功能是加强股骨颈根部;中部为疏松皮质骨;而到远端则为松质骨。中远     

Mechanical considerations in impaction bone grafting

In impaction grafting of contained bone defects after revision joint arthroplasty the graft behaves as a friable aggregate and its resistance to complex forces depends on grading, normal load and compaction. Bone mills in current use produce a distribution of particle sizes more uniform than is desirable for maximising resistance to shear stresses. We have performed experiments in vitro using morsellised allograft bone from the femoral head which have shown that its mechanical properties improve with increasing normal load and with increasing shear strains (strain hardening). The mechanical strength also increases with increasing compaction energy, and with the addition of bioglass particles to make good the deficiency in small and very small fragments. Donor femoral heads may be milled while frozen without affecting the profile of the particle size. Osteoporotic femoral heads provide a similar grading of sizes, although fewer particles are obtained from each specimen. Our findings have implications for current practice and for the future development of materials and techniques.     

In vitro stability of cemented and cementless femoral stems with compaction.

Rigidity of initial fixation is a key factor contributing to the longevity of cemented and cementless femoral components in total hip arthroplasty. The objective of this study was to measure the initial stability of primary cemented and cementless femoral components under load when 15 pairs of cadaveric femurs were prepared by outward compaction of femoral cancellous bone in situ or by conventional extraction broaching. Three-dimensional micromotion was measured at proximal and distal locations on the femoral components using a device with spherical targets and linear variable differential transformers. External loads simulating the stance phases of level walking and stair ascent were applied to the femoral components by a materials test machine. Bone preparation method significantly affected each of the translation and rotation components of micromotion with cemented and cementless fixation. Micromotion with broaching was consistently greater than with compaction. Compared with compaction, the magnitude of the micromotion translation vector for broaching was an average of 3.9 (standard deviation, 3.1) times greater with cemented fixation, and an average of 2.3 (standard deviation, 1.4) times greater with cementless fixation. The results of this study showed the effectiveness of compaction of femoral cancellous bone in improving the initial stability of cemented and cementless femoral components in primary total hip arthroplasty.     

不同频率全身振动训练对绝经期妇女血压和下肢骨密度影响

目的探讨振动训练对绝经后女性血压和骨密度影响。方法招募77名受试者,并进行筛选确定和分组;进行单次振动训练,训练结束后对所有受试者进行24 h动态血压监测;血压监测结束后进行前测(血压、骨密度、GH、IGF-1),前测结束后进行为期24周振动训练干预;24周训练结束后进行后测。利用单因素方法分析,比较组间差异,利用独立样本t检验实验前后差异。结果单次振动训练后进行24 h血压监测,高频振动组在5:00-10:00时间段收缩压有显著上升趋势,显著高于中频振动组、低频振动组、对照组(P0.05);中频振动组收缩压显著低于高频振动组、低频振动组和对照组;经过24周训练后高频振动组、中频振动组、低频振动组后测收缩压均显著低于运动干预前且显著低于对照组(P0.05);高频振动组、中频振动组后测股骨颈密度、大转子密度、Ward三角区骨密度、GH、IGF-1水平显著高于前测和对照组(P0.05结论单次高频振动训练能够引起绝经后女性高血压晨峰现象,在没有适应的情况下对绝经后女性进行高频振动训练存在一定风险。单次中频振动训练后绝经后女性出现收缩压舒张压下降情况。长期接受中频和高频振动训练,可以显著降低绝经期妇女血压,增加其下肢骨密度。     

Lengthening of double-looped tendon graft constructs in three regions after cyclic loading: a study using Roentgen stereophotogrammetric analysis.

Lengthening of a double-looped tendon graft construct used to reconstruct the anterior cruciate ligament (ACL) can result in an increase in anterior knee laxity and affect the stability of the reconstructed knee. Three possible regions where lengthening of the construct can occur are (1) the region of the tibial fixation, (2) the region of the femoral fixation, and (3) the region of the graft between the fixations. One objective of this study was to demonstrate the feasibility of using Roentgen stereophotogrammetric analysis (RSA) to determine the lengthening in each region of a double-looped graft construct subjected to cyclic loading. A second objective was to determine which region(s) contributes most to an increase in length of this graft construct. Radio-opaque markers were attached to ten grafts to measure the lengthening in each of the three regions. Each graft was passed through a tibial tunnel in a bovine tibia, looped around a rigid cross-pin, and fixed to the tibia with a Washerloc fixation device. The grafts were cyclically loaded for 225,000 cycles from 20 to 170 N. Prior to and at intervals during the cyclic loading, simultaneous radiographs were taken of the tibia and graft. RSA was used to determine the 3-dimensional coordinates of the markers from which the lengthening in each region was computed at each interval. The regions of the tibial and femoral fixations were the largest contributors to the increase in length of the graft, with maximum average values of 0.91 and 0.76 mm respectively after 225,000 cycles. The region between the fixations contributed least to lengthening of the graft, with a maximum average value of 0.23 mm. More than 90% of the lengthening in each region occurred before 100,000 cycles of loading. RSA proved to be a useful method for measuring lengthening in all three regions of the graft construct. Lengthening of the graft construct in both regions of fixation is sufficiently large that the combined contributions may cause a recurrence of instability in some knees.     

Allogenic bone and HA-coatings.

Summary Bone reconstruction by allogeneic bone is often used in conjunction with the implantation of an HA-coated device in order to obtain the osteointegration of this latter. We studied the histological behavior of 9 allogeneic implantations in contact either with the HA-coating of acetabular component or around the femoral stem. Normal cancellous bone could be evidenced in the implantation zone around the femoral stem, whereas abnormal tissue consisting either of dead cancellous bone or a connective tissue patchwork was found in the retroacetabular region. Immune cells and macrophages with phagocytosed metal or polymer particles occurred in these latter sections. This study suggests that integration of the HA-coating within the allogeneic bone graft is directly linked to the integration ability of the allogeneic material.