Do Ceramic Femoral Heads Reduce Taper Fretting Corrosion in Hip Arthroplasty? A Retrieval Study

Background

Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads.

Questions/purposes

We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads.

Methods

One hundred femoral head-stem pairs were analyzed for evidence of fretting and corrosion using a visual scoring technique based on the severity and extent of fretting and corrosion damage observed at the taper. A matched cohort design was used in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design, and flexural rigidity.

Results

Fretting and corrosion scores were lower for the stems in the ceramic head cohort (p = 0.03). Stem alloy (p = 0.004) and lower stem flexural rigidity (Spearman’s rho = −0.32, p = 0.02) predicted stem fretting and corrosion damage in the ceramic head cohort but not in the metal head cohort. The mechanism of mechanically assisted crevice corrosion was similar in both cohorts although in the case of ceramic femoral heads, only one of the two surfaces (the male metal taper) engaged in the oxide abrasion and repassivation process.

Conclusions

The results suggest that by using a ceramic femoral head, CoCr fretting and corrosion from the modular head-neck taper may be mitigated but not eliminated.

Clinical Relevance

The findings of this study support further study of the role of ceramic heads in potentially reducing femoral taper corrosion.     

Ideal Femoral Head Size in Total Hip Arthroplasty Balances Stability and Volumetric Wear

Background

Over the last several years, a trend towards increasing femoral head size in total hip arthroplasty to improve stability and impingement free range of motion has been observed.

Purpose

The specific questions we sought to answer in our review were: (1) What are the potential advantages and disadvantages of metal-on-metal, ceramic-on-ceramic, and metal-on-polyethylene bearings? (2) What is effect that femoral head size has on joint kinematics? (3) What is the effect that large femoral heads have on bearing surface wear?

Methods

A PubMed search and a review of 2012 Orthopaedic Research Society abstracts was performed and articles were chosen that directly answered components of the specific aims and that reported outcomes with contemporary implant designs or materials.

Results

A review of the literature suggests that increasing femoral head size decreases the risk of postoperative dislocation and improves impingement free range of motion; however, volumetric wear increases with large femoral heads on polyethylene and increases corrosion of the stem in large metal-on-metal modular total hip arthroplasty (THA); however, the risk of potentially developing osteolysis or adverse reactions to metal debris respectively is still unknown. Further, the effect of large femoral heads with ceramic-on-ceramic THA is unclear, due to limited availability and published data.

Conclusions

Surgeons must balance the benefits of larger head size with the increased risk of volumetric wear when determining the appropriate head size for a given patient.     

Closed reduction, internal fixation with quadratus femoris muscle pedicle bone grafting in displaced femoral neck fracture

Background:

Management of femoral neck fracture is still considered as an unsolved problem. It is more evident in displaced fractures where this fracture is considered as some sort of vascular insult to the head of the femur. We have used closed reduction, internal fixation and quadratus femoris muscle pedicle bone grafting in fresh displaced femoral neck fractures.

Materials and Methods:

From April 1996 to December 2004 we operated 73 consecutive patients of displaced femoral neck fracture in the age group of 24 to 81 years, mean age being 54.6 years. The patients were operated within one week of injury, the mean delay being 3.6 days. Closed reduction internal fixation along with quadratus femoris muscle pedicle bone grafting was done in all cases. They were followed up for an average period of 5.6 years (range 2-11 years).

Results:

Results were assessed according to modified Harris Hip Scoring system and found to be excellent in 53, good in 12, fair in six and poor in two patients. Bony union occurred in 68 cases, no patient developed avascular necrosis (AVN) till date.

Conclusion:

For fresh displaced femoral neck fracture in physiologically active patients closed reduction, internal fixation and quadratus femoris muscle pedicle bone grafting is a suitable option to secure union and prevent development of AVN.     

Cell therapy of hip osteonecrosis with autologous bone marrow grafting

Background:

One of the reasons for bone remodeling leading to an insufficient creeping substitution after osteonecrosis in the femoral head may be the small number of progenitor cells in the proximal femur and the trochanteric region. Because of this lack of progenitor cells, treatment modalities should stimulate and guide bone remodeling to sufficient creeping substitution to preserve the integrity of the femoral head. Core decompression with bone graft is used frequently in the treatment of osteonecrosis of the femoral head. In the current series, grafting was done with autologous bone marrow obtained from the iliac crest of patients operated on for early stages of osteonecrosis of the hip before collapse with the hypothesis that before stage of subchondral collapse, increasing the number of progenitor cells in the proximal femur will stimulate bone remodeling and creeping substitution and thereby improve functional outcome.

Materials and Methods:

Between 1990 and 2000, 342 patients (534 hips) with avascular osteonecrosis at early stages (Stages I and II) were treated with core decompression and autologous bone marrow grafting obtained from the iliac crest of patients operated on for osteonecrosis of the hip. The percentage of hips affected by osteonecrosis in this series of 534 hips was 19% in patients taking corticosteroids, 28% in patients with excessive alcohol intake, and 31% in patients with sickle cell disease. The mean age of the patients at the time of decompression and autologous bone marrow grafting was 39 years (range: 16–61 years). The aspirated marrow was reduced in volume by concentration and injected into the femoral head after core decompression with a small trocar. To measure the number of progenitor cells transplanted, the fibroblast colony forming unit was used as an indicator of the stroma cell activity.

Results:

Patients were followed up from 8 to 18 years. The outcome was determined by the changes in the Harris hip score, progression in radiographic stages, change in volume determined by digitizing area of the necrosis on the different cuts obtained on MRI, and by the need for hip replacement. Total hip replacement was necessary in 94 hips (evolution to collapse) among the 534 hips operated before collapse (Stages I and II). Sixty-nine hips with stage I osteonecrosis of the femoral head at the time of surgery demonstrated total resolution of osteonecrosis based on preoperative and postoperative MRI studies; these hips did not show any changes on plain radiographs. Before treatment, these 69 osteonecrosis had only a marginal band like pattern as abnormal signal and a volume less than 20 cubic centimeters. The intralesional area had kept a normal signal as regards the signal of the femoral head outside the osteonecrosis area. For the 371 other hips without collapse at the most recent follow up (average 12 years), the mean preoperative volume of the osteonecrosis was 26 cm³ (minimum 12, maximum 30 cm³). The mean volume of the abnormal signal measured on MRI at the most recent follow up (mean 12 years) was 12 cm³. The abnormal signal persisting as a sequelae was seen on T1 images as an intralesional area of low intensity signal with a disappearance of the marginal band like pattern.

Conclusion:

According to our experience, best indication for the procedure is symptomatic hips with osteonecrosis without collapse. In some patients who had Steinberg stage III osteonecrosis (subchondral lucency, no collapse) successful outcomes (no further surgery) has been obtained between 5 to 10 years. Therefore in selected patients, even more advanced disease can be considered for core decompression. Patients who had the greater number of progenitor cells transplanted in their hips had better outcomes.     

Evidence for Using Bisphosphonate to Treat Legg-Calvé-Perthes Disease

Background

The rationale for using bisphosphonate (BP) therapy for Legg-Calvé-Perthes disease (LCPD) is the potential to prevent substantial femoral head deformity during the fragmentation phase by inhibiting osteoclastic bone resorption. However, it is unclear whether BP therapy decreases femoral head deformity.

Questions/purposes

In this systematic review, we answered the following questions: (1) Does bisphosphonate (BP) therapy decrease femoral head deformity and improve pain and function in LCPD or other juvenile osteonecrotic conditions? And (2) does BP therapy decrease femoral head deformity in experimental studies of juvenile femoral head osteonecrosis?

Methods

We searched the literature from 1966 to 2011 for clinical and experimental studies on BP therapy for juvenile femoral head osteonecrosis. Studies specifically addressing clinical and/or radiographic/histologic outcomes pertaining to pain and function and femoral head morphology were analyzed.

Results

Three Level IV clinical studies met our inclusion criteria. Only one study initiated BP therapy during the precollapsed stage of osteonecrosis and reported prevention of femoral head deformity in nine of 17 patients. All studies noted subjective improvements of pain and gait in patients treated with intravenous BPs. Of the eight experimental studies reviewed, seven reported reduced femoral head deformity and six found better preservation of trabecular framework in animals treated with BPs.

Conclusions

Clinical evidence lacks consistent patient groups and drug protocols to draw definitive conclusions that BP therapy can decrease femoral head deformity in juvenile osteonecrotic conditions. Experimental studies suggest BP therapy protects the infarcted femoral head from deformity, but it lacks bone anabolic effect. Further basic and clinical research are required to determine the potential role of BPs as a medical treatment for LCPD.     

Augmented osteosynthesis with tensor fascia latae muscle pedicle bone grafting in neglected femoral neck fracture

Background:

Neglected intracapsular femoral neck fracture in young patients may fail to unite because of the excessive shearing strain at the fracture site and it is a surgical challenge to any orthopedic surgeon. The problem is compounded by resorption of the femoral neck and avascular necrosis (AVN) of femoral head. There is no satisfactory solution available in the management of femoral neck fracture as far as the union of the fracture and AVN of femoral head are concerned. Muscle pedicle bone grafting has been advocated to provide additional blood supply to the femoral head. We report a retrospective analysis of 48 cases of neglected femoral neck fracture treated by internal fixation and tensor fascia latae based muscle pedicle bone grafting.

Materials and Methods:

48 patients with femoral neck fractures with age varied from 20 to 53 years (average age 32.9 years) with male to female ratio of 2:1 were enrolled. All fractures were more than 3 weeks old with mean delay being 86 days (22–150 days). Open reduction and internal fixation along with tensor fascia latae muscle pedicle bone grafting was done in all cases. It was supplemented by multiple drilling and cortico-cancellous bone grafting. Fracture fixation was done with three parallel 6.5-mm AO cannulated cancellous lag screws and the graft fixed with a 4-mm cancellous screw to provide a secure fixation. During the followup period of 2-6.8 years (average 4.4 years) the results were assessed clinically by modified Harris hip scoring system and radiologically by the evidence of signs of fracture union.

Results:

Union was achieved in 41/48 (85.41%) cases which were followed for an average period of 4.4 years (2–6.8 years) with good functional results and ability to squat and sit cross-legged. Results were assessed according to modified Harris Hip Scoring system and found to be excellent in 19, good in 22, fair in 5, and poor in 2 patients. Complications were nonunion, (n=3) avascular necrosis (n=2), and coxa vara deformity (n=2).

Conclusion:

Internal fixation with muscle pedicle bone grafting is a suitable option to secure union in neglected femoral neck fractures in physiologically active patients with late presentation.     

Use of irradiated autologous bone in joint sparing endoprosthetic femoral replacement tumor surgery

Background:

Joint preservation is usually attempted in cases of bone tumors, though insufficient bone following tumour resection may prevent fixation of conventional joint sparing prosthesis. To preserve the hip joint in skeletally immature patients, we have combined autologous proximal femoral irradiation and intercalary re-implantation with custom made distal femoral replacements.

Materials and Methods:

A retrospective cohort study of four patients (aged 4-12 years); in whom irradiated autologous bone was combined with an extendable distal femoral endoprostheses was performed. There were three cases of osteosarcoma and one case of Ewing’s sarcoma.

Results:

At a mean follow-up of 70.5 months (range 26-185 months), all four patients were alive without evidence of local recurrence. There was no evidence of metastatic disease in three patients while one patient showed chest metastatic disease at presentation. In all cases, the irradiated segment of bone united with the proximal femur and demonstrated bone ongrowth at the prosthetic collar. There were no cases of loosening or peri-prosthetic fracture. One implant was revised after 14 years following fracture of the extending component of the endoprosthesis.

Conclusions:

We report encouraging results utilizing irradiated autologous proximal femoral bone combined with distal femoral replacement in skeletally immature patients.     

Osteonecrosis of femoral head: Treatment by core decompression and vascular pedicle grafting

Background:

Femoral head-preserving core decompression and bone grafting have shown excellent result in preventing collapse. The use of vascularized grafts have shown better clinical results. The vascular pedicle bone graft is an easy to perform operation and does not require special equipment. We analyzed and report a series of patients of osteonecrosis of femoral head treated by core decompression and vascular pedicle grafting of part of iliac crest based on deep circumflex iliac vessels.

Materials and Methods:

The article comprises of the retrospective study of 31 patients of osteonecrosis of femoral head in stage II and III treated with core decompression and vascular pedicle grafting by using part of iliac crest with deep circumflex iliac vessels from January 1990 to December 2005. The young patients with a mean age 32 years (18–52 years) with a minimum follow-up of five years were included for analysis. Sixteen patients had osteonecrosis following alcohol abuse, 12 patients following corticosteroid consumption, 3 patients had idiopathic osteonecrosis. Nine patients were stage IIB, and 22 patients were stage IIIC according to ARCO''s system. The core decompression and vascular pedicle grafting was performed by anterior approach by using part of iliac crest with deep circumflex iliac vessels.

Results:

Digital subtraction arteriography performed in 9 patients at the end of 12 weeks showed the patency of deep circumflex artery in all cases, and bone scan performed in 6 other patients showed high uptake in the grafted area of the femoral head proving the efficacy of the operative procedure. Out of 31 patients, only one patient progressed to collapse and total joint replacement was advised. At the final follow up period of 5–8 years, Harris Hip Score improved mean ± SD of 28.2 ± 6.4 (p < 0.05). Forty-eight percent of patients had an improvement in Harris Hip Score of more that 28 points.

Conclusion:

The core decompression and vascular pedicle grafting reduces the intraosseous tension to achieve early revascularization of ischemic femoral head. The high percentage of marrow and osteogenic cells survive within a vascularized pedicle graft, which helps in early vascularization and we have been able to achieve good outcome.     

Effect of a bisphosphonate and selective estrogen receptor modulator on bone remodeling in streptozotocin-induced diabetes and ovariectomized rat model

Background Context

Diabetes and menopause can cause severe osteoporosis. In general, menopause and diabetes can lead to an imbalance in bone turnover, which results in secondary osteoporosis. However, the efficacy of antiresorptive drugs against this form of osteoporosis has not been extensively evaluated.

The Effect of Bisphosphonates on Bone Mineral Density in Metastatic Prostate Cancer Patients Who Are Treated with Anti-Androgen Drugs and Radiotherapy

Objective

To evaluate the potential effect of bisphosphonates on bone mineral density (BMD) in patients who are treated with anti-androgen drugs and radiotherapy for metastatic prostate cancer.

Materials and Methods

The data of 31 patients with metastatic prostate cancer who were treated with anti-androgen drugs and radiotherapy during a 1-year period were retrospectively reviewed. Patients were divided in 2 groups, in which 17 patients in group 1 were treated with zoledronic acid (4 mg/month, intravenous) and 14 patients in group 2 who did not receive zoledronic acid. BMD was measured before the treatment and at the end of the 1st year by dual energy X-ray absorptiometry. Statistical analyses were performed with the T test.

Results

Mean age of the patients was 71.42 ± 6.7(range 59-85) years. A significant increase was noted for pelvic bone, femoral neck, and lumbar vertebrae t scores when pretreatment and 1st year measurements were compared in group 1 (p < 0.05). In group 2 a significant decrease was noted for pelvic bone and femoral neck t scores at the end of the 1st year (p < 0.05). A significant increase was noted for pelvic bone and femoral neck follow-up in BMD values at the end of the 1st year compared to initial measurements in group 1. A significant decrease was noted for lumbar vertebrae follow-up in BMD values at the end of the 1st year when compared to initial values in group 2.

Conclusion

Zoledronic acid significantly increases BMD and delays unfavorable outcomes for bones in men who are treated with anti-androgen drugs and radiotherapy for metastatic prostate cancer.Key Words: Metastatic prostate cancer, Osteoporosis, Radiotherapy, Bisphosphonate therapy     

Calcar femorale grafting in the hemiarthroplasty of the hip for unstable inter trochanteric fractures

Background:

The sliding screw-plate devices and cephalo-medullary nail devices have performed well in stable inter-trochanteric fractures in patients with reasonably good quality of bone. However, their suboptimal performance in comminuted fractures in the presence of osteoporotic bone has prompted many surgeons to consider bipolar hemiarthroplasty as the primary modality of management of comminuted inter-trochanteric fractures in elderly patients. However, long term stability of the hemiarthroplasty implant also may be compromised due to the presence of postero-medial bone loss at the area of the calcar.

Materials and Methods:

We have presented a simple and effective technique of calcar grafting by harvesting cortical bone strut from the neck of the fractured femur. A total of 34 patients with inter-trochanteric fractures of the femur were treated with calcar grafting. The mean age was 79.2 years. The graft was harvested from the calcar region of the head and neck fragment of the femur and wedged between the medial femoral cortex and medial edge of the prosthesis. The mean followup period was 54.5 months.

Results:

In 32 of 34 (94%) patients in our series, the calcar graft healed well without dislodgement. There was graft resorption in two patients associated with subsidence of the implant and loosening.

Conclusion:

Calcar grafting using this technique provides stability to the implant in the presence of comminution and incorporates well in the majority of patients. Donor site morbidity of graft harvesting is also avoided.     

Cementless hemiarthroplasty for femoral neck fractures in elderly patients

Objectives:

The use of cement is associated with increased morbidity and mortality rate in elderly patients, hence cementless hemiarthroplasty is suggested. We evaluated the results of cementless hemiarthroplasty for femoral neck fractures in elderly patients with high-risk clinical problems.

Materials and Methods:

Forty-eight patients (29 females, 19 males) with a mean age of 88 years (range: 78 to 102 years). having femoral neck fractures were treated with the use of cementless hemiarthroplasty. Porous-coated femoral stems were used in 30 patients (62%) and modular type femoral revision stems in 18 patients (38%). Bipolar femoral heads were used in all patients. Radiological follow-up after operation was done at the one, three, six months and annually.

Results:

The mean follow-up period was 4.2 years (range: 18 months to eight years). None of the patients died during hospitalization. Medical complications occurred in six patients (12%) within the follow-up period and four patients (8%) died within this period. Only two hips were converted to total hip arthroplasty due to acetabular erosion. Femoral revision was planned for one patient with a subsidence of > 3 mm. None of the patients had acetabular protrusion or heterotopic ossification. The mean Harris-hip score was 84 (range: 52 to 92). Dislocation occured in one patient (2%).

Conclusion:

Cementless hemiarthroplasty is a suitable method of treatment for femoral neck fractures in elderly patients with high-risk clinical problems especially of a cardiopulmonary nature. This method decreases the risk of hypotension and fat embolism associated with cemented hemiarthroplasty.     

Metabolic development of necrotic bone in the femoral head following resurfacing arthroplasty. A clinical [18F]fluoride-PET study in 11 asymptomatic hips

Background and purpose

One concern regarding resurfacing arthroplasty is the viability of the diminished femoral head and the postoperative risk of collapse, or a femoral neck fracture. ¹⁸F-fluoride positron emission tomography (F-PET) enables us to assess bone viability despite there being a covering metal component. By F-PET studies, we recently showed the absence of metabolism in the remaining part of femoral heads, 1–4 years after surgery in 11 of 46 consecutive cases. We now present the further development of bone metabolism in these 11 cases.

Patients and methods

10 patients (11 chips) with previously shown loss of femoral head metabolism were evaluated by radiography and repeated F-PET scans, 3–6.5 years after surgery. The size of the area with low ¹⁸F-fluoride PET uptake in the femoral head was compared to that in earlier PET images.

Results

No patients had any clinical symptoms; nor was any necrotic bone area visible in plain radiographs. On F-PET scans, 2 patients showed a diminished area with low uptake, 4 were unchanged, and 5 had enlarged areas.

Interpretation

Bone metabolism surrounding a volume of bone with no metabolic activity changes dynamically even 5 years after surgery. The presence of bone with minor uptake of F-tracer, indicating low or no bone metabolism, with further progression in 5 of 11 cases leads us to conclude that resurfacing THA should be used restrictively.One concern with resurfacing arthroplasty of the hip is the viability of the diminished femoral head. During the surgical procedure, the blood supply to the remaining part of the head might be damaged (Howie et al. 1993, Nötzli et al. 2002, Steffen et al. 2005, Khan et al. 2007). ¹⁸F-fluoride positron emission tomography (F-PET) is a sensitive and non-invasive diagnostic method for analysis of bone metabolism (Grant et al. 2008) associated with new bone formation (Sörensen et al. 2003), and bone viability (Ullmark et al. 2007). Validation studies to correlate F-PET with bone histomorphometry have been performed (Messa et al. 1993, Piert et al. 2001).In a previous prospective study of 14 patients (Ullmark et al. 2009) who received an ASR resurfacing arthroplasty (DePuy Johnsson and Johnsson, Warsaw, IN), F-PET/CT scans were performed 1 week, 4 months, and 12 months after surgery. 4 of these 14 patients were found to have lost bone metabolism (measured by F-PET/CT) in the remaining part of their femoral heads, assessed as osteonecrosis, without any symptoms and without signs on plain radiographs. All 14 patients had had normal metabolism at the F-PET scan 1 week after surgery. Between the 4-month and the 12-month postoperative PET scans, 4 of the 14 patients had developed an area with no metabolism. In another F-PET/CT study of 32 patients (Ullmark et al. 2011) with an ASR or DUROM resurfacing arthroplasty (Zimmer, Warsaw, IN), we performed the scans retrospectively 18–48 months after surgery. 7 cases in that study were found to have pathological non-metabolic areas in their femoral heads without there being symptoms or signs on radiographs.For the 11 cases that had been found to have lost bone metabolism in these 2 previous studies (Ullmark et al. 2009, 2011), we investigated how their bone metabolism had developed 3–6.5 years after surgery.     

Incidence of Radiographic Cam-Type Impingement in Young Patients (<50) After Femoral Neck Fracture Treated with Reduction and Internal Fixation

Background:

Cam-type femoral impingement is caused by structural abnormalities of the hip and is recognized as a cause of degenerative hip arthritis. Identifiable etiologies of this structural abnormality include congenital malformation, pediatric hip disease, and malunion of femoral neck fractures after internal fixation.

Purpose:

The purpose of this study was to determine the prevalence of radiographic impingement in healed Orthopaedic Trauma Association (OTA) type 31B fractures treated with reduction and internal fixation.

Methods:

Seventy OTA 31B hip fractures treated with internal fixation were identified from our institutional trauma database and radiographs were retrospectively reviewed for signs of impingement. Mean follow-up was 53 months after fracture. Alpha angle, Mose templates, and femoral head retroversion were the measurements used to determine impingement.

Results:

The overall prevalence of any sign of radiographic impingement was 75%. Alpha angle was elevated in 32 hips (46%), asphericity was present in 46 femoral heads (65%), and femoral head retroversion was present in 26 hips (37%). The rates were highest in displaced subcapital fractures (OTA 31B-3) with a 63% (13/19) prevalence of elevated alpha angle, 68% (14/19) prevalence of asphericity, and 47% (10/19) prevalence of retroversion.

Conclusions:

Prevalence of radiographic signs of impingement in this population is higher than expected based on population-based controls. Surgeons must be vigilant about reduction and fixation of femoral neck fractures. Malunion should be recognized as early intervention may be beneficial in improving long-term outcomes.     

Transfracture abduction osteotomy: A solution for nonunion of femoral neck fractures

Background:

Nonunion and avascular necrosis (AVN) of the femoral head remains one of the major complications following femoral neck fractures. Despite various surgical techniques and internal fixation devices, the incidence of nonunion and AVN has remained unsolved. Neglected nonunion of femoral neck fracture is common in the developing world. Treatment options include rigid internal fixation with or without bone grafting, muscle pedicle bone graft, valgus osteotomy of the proximal femur with or without bone graft, valgus osteotomy or hip arthroplasty. We conducted a retrospective analysis of cases of nonunion of femoral neck fracture treated by transfracture abduction osteotomy (TFAO).

Materials and Methods:

Over a period of 35 years (1974-2008), 30 patients with nonunion of femoral neck fractures were treated with TFAO over a period of 35 years (1974-2008), All patients were less than 50 years of age. Absence of clinical and radiological signs of union after four months was considered as nonunion. Patients more than 50 years of age were excluded from the study. Union was assessed at 6 months radiologically. Limb length was measured at six months. The mean duration of femoral neck fracture was 19 months (range 4 months 10 years). Results were analyzed in terms of radiological union at six months. Average followup was five years and six months.

Results:

Consistent union was noted at the followup after six months in 29 cases. One case was lost to followup after five and one-half months postoperatively. However, the fracture had united in this case at the last followup. Average shortening of the limb at six months was 1.9 cm. Average neck shaft angle was 127° (range 120-145°). Five cases went into AVN but were asymptomatic. Two cases required reoperation due to back out of Moore''s pins. These were reopened and cancellous screws were inserted in the same tracks.

Conclusions:

Consistent union of nonunion femoral neck fracture was noted at the followup after six months in 29 cases. The major drawback of the procedure is immobilization of the patient in the hip spica for eight weeks.     

Local delivery of recombinant human bone morphogenetic proteins and bisphosphonate via sucrose acetate isobutyrate can prevent femoral head collapse in Legg-Calve-Perthes disease: a pilot study in pigs

Purpose

Legg-Calve-Perthes disease is a paediatric condition encompassing idiopathic osteonecrosis of the femoral head (ONFH). Preventing collapse and the need for subsequent joint replacement remains the major goal of clinical management. This exploratory study utilises a porcine model of surgically induced ONFH.

Methods

rhBMP-2 with and without zoledronic acid (ZA) was delivered by intra-osseous injection in the phase-transitioning sucrose acetate isobutyrate (SAIB) in an attempt to prevent femoral head collapse. Epiphyseal quotient (EQ) at eight weeks post-surgery was the primary outcome measure. Heterotopic ossification in the joint capsule and bisphosphonate retention in the femoral head were key secondary outcomes.

Results

Femoral heads with ONFH and no treatment all collapsed (3/3, EQ < 0.4, P < 0.05 compared to no ONFH). Local delivery of rhBMP-2/SAIB into the femoral head prevented collapse by EQ measurement one of four samples; however, this specimen still showed evidence of significant collapse. In contrast, the combination of local rhBMP-2 and local ZA prevented collapse in two of four samples. Confocal fluorescence microscopy showed locally dosed bisphosphonate entered and was retained in the femoral head. This group also showed strong Calcein signal, indicating new bone formation. Treatment with rhBMP-2 was associated with a limited amount of heterotrophic ossification in the joint capsules in some specimens.

Conclusions

Operators reported SAIB to be an efficient way to deliver rhBMP-2 to the femoral head. These data suggest that rhBMP-2 is ineffective for preventing femoral head collapse without the addition of bisphosphonate. Further research will be required to validate the clinical efficacy of a combined local rhBMP-2/bisphosphonate approach.     

Large diameter metal on metal total hip replacement for femoral neck fractures with neurological conditions: A retrospective assessment

Background:

Patients with Parkinson''s disease and poliomyelitis can have a femoral neck fracture; yet, the optimal methods of treatment for these hips remains controversial. Many constrained or semi-constrained prostheses, using constrained liners (CLs) with a locking mechanism to capture the femoral head, were used to treat femoral neck fractures in patients with neurological disorders. We retrospectively studied a group of patients with Parkinson''s disease and poliomyelitis who sustained femoral neck fractures and were treated by total hip arthroplasty using an L-MoM prosthesis.

Materials and Methods:

We retrospectively reviewed 12 hips in 12 patients who underwent large-diameter metal-on-metal (L-MoM) total hip replacement between May 2007 and October 2009. Eight of the 12 patients (8 hips; 66.7%) had Parkinson''s disease and 4 patients (4 hips; 33.3%) were affected with poliomyelitis.

Results:

The followup time was 5.2 years (range 3.6-6.0 years). At the latest followup, all the patients showed satisfactory clinical and radiographic results, with pain relief. No complications, such as dislocation or aseptic loosening occurred.

Conclusion:

We believe the use of L-MoM can diminish the rate of instability or dislocation, after operation. The L-MoM is an option for patients with Parkinson''s disease and poliomyelitis with femoral neck fracture.