Femoral bone blood flow after reaming and intramedullary canal preparation: a canine study using laser Doppler flowmetry

This study was conducted to determine the effect of intramedullary reaming and canal preparation on bone blood flow in the proximal femur. Thirty-five adult dogs were randomly assigned to have their intramedullary canals prepared after reaming in the following manner: group 1, ream only; group 2, lavage; group 3, methylmethacrylate cement introduction; group 4, cement pressurization after placing a cement restrictor; group 5, lavage then cement introduction; and group 6, lavage then cement pressurization. Bone blood flow was measured at both metaphyseal and diaphyseal sites by using laser Doppler flowmetry before reaming, after reaming, after lavage, after cementing, and at 6 weeks after the procedure just before euthanasia. Reaming significantly decreased bone blood flow in the diaphysis (P = .046) but not in the metaphysis. Cement introduction and cement pressurization both significantly decreased bone blood flow in the metaphysis (P = .035, P = .004) and diaphysis (P = .007, P = .029). Pressurization of cement had a significantly greater relative effect than cement introduction alone in the diaphysis (P = .006) but not in the metaphysis. Lavage had no effect on bone perfusion. Bone blood flow was significantly increased at 6 weeks after the initial procedure in both the metaphysis (P = .049) and the diaphysis (P = .004). The results suggest that reaming decreases diaphyseal cortical but not metaphyseal bone blood flow significantly, whereas lavage has no effect. Cement introduction with or without pressurization has a significant detrimental effect on metaphyseal and diaphyseal blood flow. These findings have implications for intramedullary nailing and for canal preparation when performing arthroplasty.     

Torsional fixation of the femoral component in total hip arthroplasty. The effect of surgical press-fit technique.

Rotational loading of the femoral component has recently emerged as a prime factor for causing loosening and failure of total hip replacements. In this study the effect of surgical press-fit technique on torsional fixation of the femoral component was evaluated. The commonly used line-to-line reaming technique was compared to an underreaming technique using both four-fifths and one-third porous-coated anatomic medullary locking (AML) implants. Rotational micromotion, permanent rotational displacement, and slop displacement between bone and implant were measured with linearly variable differential transducers under torsional loading. The line-to-line reamed group showed significantly greater motion than both underreamed groups for all micromotion parameters. This was especially true for the slop displacement test, which revealed large amounts of displacement after a single moderate torsional load, whereas in the underreamed groups significantly less loosening was found. The line-to-line reaming technique did not achieve good rotational fixation of the femoral component. Superior rotational stability was accomplished only when the diaphysis was underreamed and tight diaphyseal fixation was achieved. The extent of the porous coating on the stem did not have a significant effect.     

Early complications after one hundred and forty-four consecutive hip revisions with impacted morselized allograft bone and cement

BACKGROUND: The use of impacted morselized allograft bone and cement in hip revision arthroplasty has been popular, but studies that specifically address intraoperative and postoperative complications have been scarce. METHODS: All complications that occurred during, and within the first year after, 144 consecutive hip revision arthroplasties (108 stems and 130 sockets) performed with impacted morselized allograft bone and cement were recorded. Clinical and radiographic follow-up evaluation was performed at three months and at one year after surgery for all patients except eight (seven who had died of causes unrelated to the hip surgery and one who had sustained a stroke). Of these eight patients, seven had a six-week and/or three-month follow-up evaluation. RESULTS: Thirty-nine femoral fractures occurred in thirty-seven hips; twenty-nine of the fractures occurred during surgery and ten, within five months after surgery. Of the intraoperative femoral fractures, twelve were proximal, nine were diaphyseal, and eight involved the greater trochanter. Of the postoperative femoral fractures, one was proximal and nine were diaphyseal. Other intraoperative complications were the creation of a femoral cortical window in seven hips and incidental perforation of the femoral cortex in fourteen. Multivariate analysis showed the risk factors for femoral fracture during or after revision to be concomitant disease, greater deficiency of the femoral bone stock, and an intraoperative femoral window or perforation. Other complications included dislocation of the femoral head in nine hips, deep infection in one hip, persistence of preoperative deep infection in one hip, and superficial wound infection requiring wound débridement in two hips. CONCLUSIONS: We found the complication rate to be high after hip revision arthroplasty performed with impacted morselized allograft bone and cement. The most serious complication was postoperative diaphyseal femoral fracture.     

Ipsilateral fractures of the femoral neck and shaft

Ipsilateral femoral shaft and neck fractures are difficult to treat. From 1989 to 1998, we treated 18 patients with these complex fractures. There were 14 male and 4 female with an average age of 40 years. Most resulted from high-energy trauma. The average follow-up period is 41 months. All but one of the fractures united well. The mean time to union is 5.2+/-2.3 months in the diaphysis and 4.16+/-2 months in the neck. No cases of the femoral neck fracture or osteonecrosis of the femoral head were observed during the follow-up period. Fourteen cases were treated with a standard protocol of plates for diaphyseal fractures and lag screws or dynamic hip screws (DHS) fixations for the femoral neck fractures. There were 13 good and 1 fair functional results. Two neglected neck fractures were treated with interlocking nailing for diaphyseal fracture with fair results. We conclude that a plate on the shaft and sliding hip screws or separate screws in the hip is a reliable method for ipsilateral femoral neck and shaft fractures.     

Concomitant sickle cell disease and skeletal fluorosis

Skeletal fluorosis typically manifests as a diffuse increase in bone density, whereas avascular necrosis of the epiphyses and diaphyseal marrow are the main skeletal manifestations of sickle cell disease. The diagnostic and therapeutic challenges raised when both disorders are present are illustrated by two cases in Senegalese patients from an area characterized by high fluoride contents in the water and soil. Both had SS sickle cell disease. Skeletal fluorosis was diagnosed during evaluation for avascular necrosis in one patient and in the wake of septic arthritis in the other. Femoral head necrosis is difficult to identify in a patient with skeletal fluorosis. The bone lesions due to sickle cell disease and those due to fluorosis can mimic other bone diseases, most notably metastases. The combination of sickle cell disease and fluorosis results in significant medullary canal narrowing due to cortical thickening and to accumulation of necrotic bone. When performing hip replacement surgery, careful reaming of the medullary canal may reduce the risk of iatrogenic femoral fracture and inappropriate stem placement.     

Revision Total Hip Arthroplasty for a Vancouver Type B3 Periprosthetic Fracture Using an Allograft-Cemented Stem Composite by the Telescoping Technique

We describe a case of successful revision total hip arthroplasty for a Vancouver type B3 periprosthetic femoral fracture with extensive bone stock deficiency and osteoporotic diaphyseal bone. The femur was reconstructed with an allograft-cemented stem composite using a telescoping technique and a drainage hole for surplus cement. This procedure facilitated stable stem fixation to the host femur without cement interference and bony fusion between the allograft and host bone, as revealed by bone scintigraphy. This technique provides a surgical option for a severe periprosthetic femoral fracture in which the femoral diaphyseal bone is too osteoporotic to support the fixation of an allograft-cementless stem composite.     

Changes in Femoral Cortical Porosity After Reaming and Intramedullary Canal Preparation in a Canine Model

This study examined changes in femoral cortical porosity resulting from femoral canal preparation during cemented total hip arthroplasty (THA). Twenty-four canines were randomly assigned to 3 groups: (1) reaming only, (2) cementing without pressurization, and (3) cementing with pressurization. Femoral cortical porosity was measured from histologic samples of the femurs at 7 positions. Reaming during canal preparation significantly increased cortical porosity. Cementing further increased cortical porosity, whereas pressurization of cement helped to counteract the increase in cortical porosity caused by cementing alone. Cortical porosity was considered to be a marker for bone mineral density (BMD) during the early phase of peri-implant healing around cemented stems. To maximize bone mineral density after cemented total hip arthroplasty, we suggest using implants that do not require reaming and pressurizing cement appropriately.     

Subcapital fractures associated with extensive osteonecrosis of the femoral head

The authors reviewed 10 patients with subcapital fractures associated with extensive osteonecrosis of the femoral head and distinguished these fractures from traumatic femoral neck fractures The mean age of the patients was 52 years (range, 36-68 years). Nine patients were younger than 60 years. Eight patients had risk factors for osteonecrosis. Necrosis was extensive and involved nearly the whole femoral head. Fracture occurred at the junction between a necrotic bone and reparative bone and extended downward through the reparative interface to the healthy inferior cortex of the femoral neck. Patients experienced hip pain that was aggravated gradually during a period of 1 to 24 weeks before diagnosis of the fracture. In all patients, the opposite femoral head was involved with osteonecrosis. In two femoral heads, slight collapse or subchondral fracture (crescent sign) also was observed. No patient had a history of precipitating trauma. In patients younger than 60 years with a subcapital fracture, fracture associated with extensive osteonecrosis of the femoral head should be suspected when a history of trauma is not obvious, when the opposite hip shows findings of osteonecrosis, and when the patient has a risk factor of osteonecrosis. In these fractures, osteosynthesis rarely should be considered because of the high failure rate caused by additional progression of extensive osteonecrosis and the probability of nonunion.     

Drépanocytose associée à une fluorose osseuse

Skeletal fluorosis typically manifests as a diffuse increase in bone density, whereas avascular necrosis of the epiphyses and diaphyseal marrow are the main skeletal manifestations of sickle cell disease. The diagnostic and therapeutic challenges raised when both disorders are present are illustrated by two cases in Senegalese patients from an area characterized by high fluoride contents in the water and soil. Both had SS sickle cell disease. Skeletal fluorosis was diagnosed during evaluation for avascular necrosis in one patient and in the wake of septic arthritis in the other. Femoral head necrosis is difficult to identify in a patient with skeletal fluorosis. The bone lesions due to sickle cell disease and those due to fluorosis  can mimic other bone diseases, most notably metastases. The combination of sickle cell disease and fluorosis results in significant medullary canal narrowing due to cortical thickening and to accumulation of necrotic bone. When performing hip replacement surgery, careful reaming of the medullary canal may reduce the risk of iatrogenic femoral fracture and inappropriate stem placement.     

The effect of polymethylmethacrylate on bone: an experimental study

In order to assess the response of bone to low-viscosity polymethylmethacrylate, CMW or Simplex acrylic cement was digitally packed while in a doughy state into drill holes in the proximal diaphysis in each of four long bones (humeri and tibiae) of mongrel dogs. Histological assessment was performed in areas of minimal load at the interface between the viscoelastic bone and the acrylic cement. Decalcified and undecalcified sections were evaluated and a remodeling or activity index calculated. Fluorescent labeling studies were performed in order to assess bone growth. Animals were killed at 2, 4 or 5 months. Histological analysis showed a thin connective-tissue membrane containing scattered giant cells and histiocytes at the bone-cement interface. Inflammation was not an important facet of this response. The marrow and trabecular bone were viable, except for scattered localized areas of marrow necrosis and fibrosis immediately adjacent to the cement. The bone adjacent to the cement showed a lower remodeling or activity index, fewer fluorescent bands, and smaller distances between successive bands, suggesting decreased bone formation and turnover. The etiology of these findings may include a vascular disturbance secondary to disruption of the cortical and marrow circulation, temperature effects during cement polymerization, and/or chemical effects from the acrylic monomer.     

Pathology of femoral head collapse following transtrochanteric rotational osteotomy for osteonecrosis

We investigated the pathology of femoral head collapse following transtrochanteric anterior rotational osteotomy. Six femoral heads were obtained during total hip arthroplasty some 2–12 years after osteotomy. In all cases, the preoperatively necrotic lesions exhibited mostly osteonecrosis with accumulation of bone marrow cell debris and trabecular bone with empty lacunae, although repair tissue such as granulation tissue and appositional bone formation were observed in limited areas in some cases. In the transposed intact articular surface of the femoral head, osteoarthritic changes such as fissure penetration to the subchondral bone and osteophyte formation were commonly observed. In newly created subchondral areas at weight-bearing sites, trabecular thickness and the number of trabecular bones had decreased, with few osteoblasts, osteoclasts, and osteocytes being present, resulting in a coarse lamellar structure of the trabecular bone. These findings suggest that transposed areas in cases of failure consist mostly of low-turnover osteoporotic lesions which could cause collapse of the femoral head. Received: 5 October 1999     

Maximum temperatures of 89°C recorded during the mechanical preparation of 35 femoral heads for resurfacing

Background and purpose We noticed that our instruments were often too hot to touch after preparing the femoral head for resurfacing, and questioned whether the heat generated could exceed temperatures known to cause osteonecrosis.

Patients and methods Using an infra-red thermal imaging camera, we measured real-time femoral head temperatures during femoral head reaming in 35 patients undergoing resurfacing hip arthroplasty. 7 patients received an ASR, 8 received a Cormet, and 20 received a Birmingham resurfacing arthroplasty.

Results The maximum temperature recorded was 89°C. The temperature exceeded 47°C in 28 patients and 70°C in 11. The mean duration of most stages of head preparation was less than 1 min. The mean time exceeded 1 min only on peripheral head reaming of the ASR system. At temperatures lower than 47°C, only 2 femoral heads were exposed long enough to cause osteonecrosis. The highest mean maximum temperatures recorded were 54°C when the proximal femoral head was resected with an oscillating saw and 47°C during peripheral reaming with the crown drill. The modified new Birmingham resurfacing proximal femoral head reamer substantially reduced the maximum temperatures generated. Lavage reduced temperatures to a mean of 18°C.

Interpretation 11 patients were subjected to temperatures sufficient to cause osteonecrosis secondary to thermal insult, regardless of the duration of reaming. In 2 cases only, the length of reaming was long enough to induce damage at lower temperatures. Lavage and sharp instruments should reduce the risk of thermal insult during hip resurfacing.     

局部无水酒精注射诱导家犬股骨头坏死的实验研究

[目的]观察局部无水酒精注射法建立家犬早期股骨头坏死模型的有效性.[方法]选取健康成年家犬18只,体重15 ～ 18 kg,两侧股骨头分别设立实验组和空白对照组,实验组行股骨头脱位和无水酒精注射处理,注射剂量为6 ml,术后分别于2、3、4周行X线片和CT扫描检查,并取材进行组织学观察,比较两组的空骨陷窝率,并进行统计学分析.[结果]术后2～4周,实验组股骨头均表现出不同程度的坏死,X线片显示关节面软骨下出现带状低密度影与伴行的带状高密度影,髋关节轴位CT平扫显示实验侧股骨头关节面下出现低密度区域,周围有斑块状硬化灶.无水酒精注射部位组织学显示部分骨小梁断裂、骨陷窝变空虚、髓腔内造血细胞减少、脂肪细胞变性坏死,LSD -t检验显示各时间点实验组空骨陷窝发生率明显高于空白对照组(P＜0.05),除2只家犬外(1只术后第3d死亡,1只术后因股骨头脱位予以剔除),16只家犬(89％)均出现明显的股骨头早期坏死.[结论]局部无水酒精注射法可以成功诱导家犬股骨头坏死,该方法可作为建立大动物早期股骨头坏死模型的有效方法.     

Quantitative CT-assisted osteodensitometry of femoral adaptive bone remodelling after uncemented total hip arthroplasty

The aim of this prospective study was to measure bone density changes and to assess adaptive bone remodelling after uncemented total hip arthroplasty with a taper-design femoral component using quantitative computer-tomography-assisted osteodensitometry. This method is able to differentiate cortical and cancellous bone structures. Twenty-seven consecutive patients (29 hips) with degenerative joint disease were enrolled in the study. Serial clinical, radiological and CT-osteodensitometry assessments were performed after the index operation. At the 2-year follow-up, the clinical outcome was rated satisfactory in all hips. The radiological assessment showed signs of osteointegration and stable fixation of all cups and stems. We observed a -17% decrease of cortical bone density and -22% decrease of cancellous bone density in the greater trochanter and femoral neck region. Cortical and cancellous bone density decrease at the level of the lesser trochanter was -9% and respectively -4%. We observed small changes of cortical bone density in the diaphyseal regions; in contrast, cancellous bone density increased (range 6% to 27%) in the diaphyseal regions. Overall, a trend of bone density recovery was observed throughout the follow-up period. Periprosthetic bone density changes at the 2-year follow-up are suggestive of stable osteointegration with proximal femoral diaphysis load transfer and moderate metaphyseal stress-shielding.     

Distal ingrowth components

The literature documents that distal ingrowth fixation provides a reproducible, durable option that can be used in many femoral revision situations. In this review, we describe our use of cylindrical, extensively porous-coated stems to achieve distal fixation. The procedure involves choosing 5 cm to 7 cm of diaphyseal bone and reaming it cylindrically for a porous-coated femoral stem. Surgical implantation is uncomplicated because the femoral diaphysis aligns the component and imparts a reproducible press-fit sensation during impaction. The complications are well documented and can be avoided with adequate exposure, intraoperative radiographs, and surgical experience. Survivorship data based on femoral revisions done at our institution with extensively porous-coated stems show overall excellent results although a relatively poorer outcome is associated with patients whose prerevision cortical damage involves bone more than 10 cm below the lesser trochanter.     

Variation of cortical hypertrophy depending on the medullary filling material: An experimental study of canine tibial diaphysis

In order to evaluate the mineralization of bone after polymethyl methacrylate cementation, measurements of the periosteal apposition were made histologically and measurements of the bone—mineral content were made by dual-photon absorptiometry of the tibial diaphysis in 15 adult mongrel dogs in paired studies. Six dogs were investigated 4 weeks after intramedullary reaming of both sides and obturation of the medullary cavity with bone—wax on one side. Nine dogs were reamed on both sides. The medullary cavities were filled with polymethyl methacrylate bone—cement and bone—wax, respectively. The authors found (1) an increased bone—mineral content and an increased periosteal apposition after filling with bone—wax in comparison with the reamed side and (2) a decreased bone—mineral content and a decreased periosteal apposition on the cemented side in comparison with bone—wax. These findings are interpreted as consequential upon repair processes with a high remodeling and mineralization rate after reaming or filling with bone—wax, whereas remodeling is inhibited after filling with acrylic bone—cement.     

股骨头坏死修复反应区的骨髓水肿及其病理改变

目的探讨股骨头坏死修复反应区骨髓水肿的病理基础和临床意义。方法随机取20个因股骨头坏死行全髋关节置换的股骨头标本，取修复反应区制作成病理切片。根据MRI脂抑像表现分为骨髓水肿组和非水肿组。将两组病理切片的显微镜下结构随机取5个视野，对于所见坏死和崩解骨组织、脂肪组织、造血组织、肉芽组织、纤维组织，进行比较。结果本研究显示骨髓水肿组肉芽组织明显较常见（x^2=13．107，P〈0．05），而无水肿组脂肪组织（x^2=17．755，P〈0．05）和造血组织（x^2=2．838，P〈0．05）较多，两组差异有统计学意义。而坏死骨小梁（x^2=0．457，P〉0．05）、崩解组织（x^2=0．037，P〉0．05）、纤维组织（x^2=0．428，P〉0.05）在两组分布相似，差异无统计学意义。结论股骨头坏死修复反应区的骨髓水肿是一种炎性反应表现，其产生机制可能与股骨头内微骨折有关，对于临床治疗的相关性尚需进一步研究。     

Thermal effects of cement mantle thickness for hip resurfacing

Hybrid hip resurfacing arthroplasty with uncemented acetabular and cemented femoral fixation is increasingly becoming popular as an alternative to total hip arthroplasty. There is concern about femoral neck fractures, and long-term survival has not yet been demonstrated. Thermal necrosis may be an important factor for neck fracture and will affect the viability of the femoral bone. This cadaveric study investigated the thermal effect of thick (1.5 mm, n = 3) and thin (0.5 mm, n = 3) cement mantles; 5 thermocouples were used to record temperature at the femoral bone/cement interface during hip resurfacing arthroplasty. The highest recorded temperatures were significantly higher when a thick cement mantle is used (45.4 degrees C), compared to a thin cement mantle (32.7 degrees C). To reduce the potential for thermal necrosis, the thin cement mantle technique is recommended.     

The effect of diaphyseal biologic fixation on clinical results and fixation of the APR-II stem

This study evaluated the effect of a grit-blasted diaphyseal surface on noncemented fixation of the Anatomic Porous Replacement II stem (APR-II, Sulzer Medica Orthopaedics, Austin, TX) for improvement of clinical results and fixation. A total of 107 consecutive total hip arthroplasties with the APR-II stem, which has proximal porous coating and a diaphyseal grit-blasted surface, were performed without cement, and 99 were studied at average 4 years. Of these hips, 37 had hydroxyapatite sprayed onto the proximal porous coating, but because there were no statistical differences for performance in any category, all stems were considered as 1 group. Clinical results were measured by the Harris hip score. Radiographic measurements of fixation, osteolysis, and bone remodeling were studied by reference to Gruen zones. Of hips, 99% had a good or excellent result by Harris hip score, with an average pain score of 42.3. Of hips, 98% had >40 points, with no patient reporting thigh pain after 3 years. There were no radiolucent lines in 94% of stems, and 100% had proximal bone ingrowth fixation. Distal cortical hypertrophy associated with tip fixation occurred in 49%, whereas proximal stress shielding was present in 43% of hips. Comparison of these clinical and radiographic results with our previous experience of bone ingrowth implants (smooth stem) suggests that bone ingrowth proximally with ongrowth in the diaphysis of the femoral stem provides better clinical and radiographic results.