Supra-condylar humerus fractures (SCHF) are amongst the most common fractures requiring surgical stabilisation in the pediatric age group (1). Closed reduction and percutaneous fixation with Kirschner wires (KW) is currently the standard of care (2). The number of KW used and their configuration has been the subject of much research (3, 4). The failure modes leading to loss of fracture reduction are not clear and have not been quantified. The aim of this study is to compare the mechanical stability of the opt-used configurations for various loading modes and contact interactions at the KW/bone interface.

A Gartland type-III SCHF was introduced to a fourth generation composite saw bone (Sawbones®, Vashon, Washington, USA). The model was CT scanned with a slice spacing of 0.5mm and pixel size 0.3×0.3mm. The CT data set was imported into AmiraDev (AmiraDev 5.2 Visage Imaging, Inc). A uniaxial mechanical test was conducted in order to measure the KW pullout forces from the distal humerus.

A model of the fractured humerus was constructed with the following steps: 1) manual segmentation; 2) surface generation of each fragment, and; 3) automatic volumetric grid generation for each fragment. The fracture was then virtually reduced and KWs were placed at the desired configurations (Fig 1a-b). For each configuration, a separate model was generated. Material properties were assigned to the bone-model elements according to the manufacturer's data sheet; Young's modulus E = 16GPa and E = 150MPa for the cortical and cancellous bone respectively. The KW were assigned a Young's modulus of 200GPa. Each of the models created in Amira was imported to a finite element application (Abaqus 6.9, DS-Simula) for structural analysis. For each of KW configuration four different torque forces load types were simulated (Fig 1c left): 1) a clockwise and counterclockwise torque with a magnitude of 1.5 NM (Newton/Meters); 2) a translational force with a magnitude of 30 N (Newtons) in the direction of the humerus shaft, and; 3) a shear force with a magnitude of 30 N in the direction parallel to the fracture plane. The results were normalised such that the maximum displacement for the crossed pin configuration with a coefficient of friction equal to zero (μ = 0) was used as unity for each load configuration. Similarly, for each of KW configuration four different translational forces load types were simulated (Fig 1c right): 1) a clockwise and counter clock-wise torque with a magnitude of 1.5 NM (Newton/Meters); 2) a translational force with a magnitude of 30N in the direction of the humerus shaft, and; 3) a shear force with a magnitude of 30N in the direction parallel to the fracture plane. The results were normalised as described above.

The common practice for insertion of distal locking screws of intramedullary (IM) nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure to patient and surgical personnel. A new technique is introduced which guides the surgeon by landmarks on the X-ray projection.

18 fresh frozen human below-knee specimens (incl. soft tissue) were used. Each specimen was instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland) and was mounted on an OR-table. Two distal interlocking techniques were performed in random order using a Siemens ARCADIS C-arm system (Siemens AG, Munich, Germany). The newly developed guided technique, guides the surgeon by visible landmarks projected onto the fluoroscopy image. A computer program plans the drilling trajectory by 2D-3D conversion and provides said guiding landmarks for drilling in real-time. No additional tracking or navigation equipment is needed.

All four distal screws (2 mediolateral, 2 anteroposterior) were placed in each procedure. Operating time, number of taken X-rays and radiation time were recorded per procedure and for each single screw.

8 procedures were performed with the freehand technique and 10 with the guided technique. A 58% reduction in number of fluoroscopy shots per screw was found for the guided technique (7.4±3.4 vs. 17.6±10.3; p < 0.001). Total radiation time was 55% lower for the guided technique (17.1 ± 3.7s vs. 37.9 ± 9.1s) (p = 0.001). Operating time was shorter by 22% in the guided technique (3.2±1.2 min vs. 4.1±2.1 min p = 0.018).

In an experimental setting, the newly developed guided freehand technique has proven to markedly reduce radiation exposure when compared to the conventional freehand technique. The method enhances established clinical workflows and does not require cost intensive add-on devices or extensive training.

A newly developed simple navigated technique has proven to markedly reduce radiation exposure and time for distal locking of intramedullary nails.

Many orthopedic departments provide their patients with implant-specific identification cards. These cards should assist patients in various security checks and while undergoing revision surgery, especially if performed far from the primary hospital. This retrospective study was performed to evaluate patients’ use of these cards.

In our department, each arthroplasty patient receives an implant-specific identification card. A phone survey was conducted among two groups of consecutive patients who underwent a lower limb arthroplasty – first group consisted of 108 patients operated a year earlier and second – 120 patients operated 3 years earlier. In the first group, 97 patients (90%) replied and in the second group – 83 patients (69%). The patients were asked the following: whether they received the card, where they keep it, what do they know about its purposes, and have they used the card for security or medical reasons.

17 patients (18%) in one-year group and 18 patients (22%) in three-years group didn’t remember the card. The rest of the patients knew the location of the card, but most of them (80% in one-year group and 72%in three-years group) knew only about the security usage of the card and not about the medical one. Many patients complained that they were not given adequate explanations about the card.

Implant-specific identification cards have significant value for arthroplasty patients. However, patients use them mostly for security checks. The medical usage of this card should be explained when they receive it, so the patients can assist their surgeons while performing a revision surgery.

Introduction: The postoperative rehabilitation after a primary knee arthroplasty may be infiuenced by a variety of factors. Nevertheless, only a few studies evaluated the effect of various factors on patients’ short-term outcome. This prospective study was conducted to evaluate the effect of different factors on patients’ function six weeks after the surgery.

Patients and methods. We prospectively recruited 107 patients with osteoarthritis who underwent an uncomplicated total knee arthroplasty, using the same prosthesis and operative technique. Following variables were collected before and after the surgery: age, BMI, visual analogue pain score at rest and during activity, preoperative range of knee motion, involvement of other joints, comorbidities (Katz index), self assessed health status, admission and discharge hemoglobin levels, amount of blood transfusions and intensity of postoperative physiotherapy.

In order to quantify patients’ level of functioning, we used a timed up and go test (TUG) and the Oxford knee score that were collected before and after the surgery. To eliminate the infiuence of postoperative weakness on rehabilitation, hand grip measurements were performed as well. A multivariate regression analysis was performed to examine the infiuence of different peri-operative variables on the outcome measures. Adjusted R2 was measured to estimate the explanatory power of infiuence of these variables.

Results: There was no significant difference between preoperative and postoperative hand grip force measurements, indicating that the general strength of the patients did not deteriorate. A postoperative TUG was worse with higher preoperative TUG and higher rest pain score (adjusted R2=0.53). The amount of improvement in TUG was better only with lower rest pain score (adjusted R2=0.06). A postoperative Oxford hip score was better only with lower rest pain score (adjusted R2=0.30). The amount of improvement in the Oxford score was not infiuenced by any of the variables (adjusted R2=0.01). Only significant infiuences (p< 0.05) are mentioned.

Discussion: Most of preoperative and postoperative measured variables, including age, BMI, comorbidities, hemoglobin concentration and amount of physiotherapy had no significant effect on patient’s functional status after uncomplicated knee arthroplasty. Only the pain at rest had infiuence on the functional result. These results suggest that patient personality has a most significant effect on knee arthroplasty results, either through pain perception or otherwise.

Introduction: Distal radius fracture in postmenopausal women is often the first clinical symptom of osteoporosis. Both patients and family physicians are generally unaware of this. It is estimated that only 15–25% of postmenopausal women with a distal radius fracture are further referred to perform a bone density examination. The purpose of the current study was to examine whether a simple intervention by the hospital staff would increase the percentage of patients that undergo diagnostic workup after suffering a fracture in the distal radius.

Patients and Methods: This prospective study included 99 women aged 48–70 seen in the emergency room for a distal radius fracture. All patients were contacted 6–8 weeks after the ER visit and asked as to whether they had received an explanation from the hospital or from the family physician about the significance of the fracture for osteoporosis, and whether they had been referred to a bone density examination. 49 patients served as a control group. The intervention group (50 patients) were then given a detailed explanation regarding the implications of the fracture for osteoporosis, and in addition, received a letter with an explanatory leaflet and an appeal to the family physician with recommendations and an article on osteoporosis.

An additional telephone survey was conducted 6–8 weeks after the first conversation to assess the influence of the intervention.

Results: 15 patients in the intervention group and 14 patients in the control group were lost to follow up or were already treated for osteoporosis before the fracture. At the second phone call 24 patients (72.7%) from the intervention group had contacted their family physician after the intervention, compared to 8 patients (22.9%) in the control group (p=0.0003). 14 patients (42.4%) from this group underwent a bone density examination, compared to 5 patients (14.3%) in the control group (p=0.0003).

Conclusion: It is of great importance that patients understand the connection between the current problem for which they are receiving treatment in the emergency setting and the possibility that there is an underlying cause. In addition the connection between the hospital and the community is very important in increasing the number of patients diagnosed and treated.

Purpose: Fracture reduction (FR) during intra-medullary nailing of long bone fractures requires an extensive use of fluoroscopic radiation. Fluoroscopy based navigation system using custom FR software is introduced of which the main advantage is its ability to track simultaneously the two fracture segments during fracture reduction. The aim of this study was to test the feasibility of this system.

Methods: 26 Patients 17 males and 7 females suffering from 10 tibial shaft and 14 femoral shaft fracture were operated using the FR software. Two trackers were attached to each of the main fracture segments. Image registration was done by acquiring fluoroscopic images including the fracture site and the two metaphysial areas of the long bone on both perpendicular planes. The system uses two cylinder models representing the fracture segments, each defined between two points chosen by the surgeon on the acquired images, these are tracked by the system. Fracture reduction was qualitatively evaluated as well as other features of the system. Overall radiation was registered.

Results: A small number (< 10) of flouroscopic images was acquired; this decreased as we gained more experience. FR software was helpful in all the cases and accomplished good and quick reduction; it reduced the need for added radiation to 2–4 verification images.

The system was utilized as well in all cases for choosing the nail point of entry, in 7 (25%) for blocking screws planning and in 4 (16%) for nail locking successfully.

Conclusion: The FR software enabled and improved significantly the performance of this surgical task with a dramatic decrease in radiation and FR time. The software still lacks the fine tuning needed for best performance.

Introduction: In 2003 the Ministry of Health in Israel added hip fractures to the DRG listing. The rational behind this move was aiming at the shortening of hip fractures waiting time to surgery and shortening of hospitalization period. Some hospitals in Israel have assigned an additional OR shift for this purpose. Hip fracture patients consist of two main sub-groups: patients who undergo hemi-arthroplasty (HA Group) and those who undergo internal fracture fixation (IFF Group). The new policy determines that DRG of internal fixation patients ends at the fifth day of their initial hospitalization after surgery. The aim of this study was to evaluate the practical effect of this policy on hip fracture management.

Patients and Methods: We retrospectively compared two major groups of patients (total 808) with hip fractures: the first group of patients was treated in 2001 (377 patients) (before the new policy came into effect) and the second in 2005 (431 patients). Each of these groups included the HA group and the IFF group. In each of the groups we compared the time to surgery, length of hospitalization, mortality rates after six months and the diurnal distribution of the operations.

Results: The length of hospitalization in 2005 was found to be shorter in the IFF group by 2.82 days (2001 – mean stay of 12.52, 2005 - 9.7 days) as opposed to the HA group where hospitalization was shorter in 2005 by a mean of only 0.42 day. Mortality rates at six months following surgery, when comparing the two major groups, were 11.3% in 2001 and 7.9% in 2005. 90% of the operations in 2005 were performed between 15:00–19:30 compared to 2001 when 90% of surgeries were evenly distributed between 15:00 and 24:00. We did not find statistically significant differences between the groups in relation to the time to surgery before and after the new policy. There was a trend towards a longer waiting time to surgery in the HA group in 2001 as well as in 2005.

Discussion: The presence of a dedicated shift, according to the new policy, made more room available for other emergency list surgeries. Hospitalization stay became shorter due to the fact that the insurer is committed to discharge patients from the IFF group after 4 days of hospitalization and to finance each additional day. In spite of the fact that waiting time to surgery was not shortened following the new policy, the majority of surgeries were performed during the afternoon sessions. It should be noted that in 2001 waiting time to surgery was already very short. Mortality data are interesting and necessitate further investigation.

Introduction: Reversed oblique subtrochanteric fractures are unstable and pose a surgical challenge. Fixation with Dynamic Hip Screw is prone to collapse with medial displacement and high rate of non or mal union. The use of Proximal Femoral Nails may result in non anatomical reduction which delays union and impedes rehabilitation. PCCP is a percutaneous plate originally designed for fixation of intertrochanteric fractures. However, the plate supports the greater trochanter and can prevent collapse of subtrochanteric fractures and rigidly secure the femoral neck. This study summarized our experience in fixating reversed oblique subtrochanteric fracture with the PCCP technique.

Patients and Methods: Between January 2005 and March 2006 26 patients who sustained reversed oblique subtrochanteric fractures (AO-31A3) were consecutively treated with PCCP. Two patients died and were excluded from this study. Patients’ age ranged between 58 and 93 (average 86, median 80). Follow-up was between 6 to 20 months (average 12). All patients were operated on a standard fracture table with the use of posterior reduction device. An attempt to reduce the fracture was done in each case prior to the surgical incision. In the majority of cases the shaft was displaced medially to the greater trochanter. The PCCP plate was introduced percutaneously and the medially displaced shaft was pulled to the plate using the reduction clamp. The rest of the procedure was done according to the regular technique of the PCCP. All patients were instructed to refrain from weight bearing for six weeks after the surgery and then resume full weigh bearing. Follow-up was in the out patient clinic 6 weeks, 3 months and one year after the surgery.

Results: Time of surgery varied between 35 to 75 minutes. There were no patients who were planned to undergo this procedure and were diverted to a different modality of fixation. All the procedures were done percutaneously. Anatomic or near anatomic reduction was achieved in all cases. All patients resumed full weigh bearing six weeks after the surgery. All but one fracture united. The patient whose fracture did not unite was blind and fell a few times during rehabilitation and eventually suffered from pull-out of the plate from the femur with breakage of the shaft screws. She underwent revision surgery with bone graft and the fracture united. Follow-up radiograms showed that the reduction was maintained in all but three patients. Medial displacement of 8–15 mm occurred in 3 patients. There were no infections.

Conclusions: While there is an ongoing debate among “nailers” vs. “platers” for the fixation of femoral neck fractures, PCCP combines the theoretical advantages of both percutaneous technique and absolute stability. In this study this biological system was found to be a reliable solution for the challenging fixation of reversed oblique (AO-31A3) subtrochanteric fractures, with high union rate, fast recovery and low complication rate.

Purpose: The purpose of this study was to assess the safety and efficacy of computed tomography (CT) guided percutaneous radiofrequency (RF) ablation of osteoid osteoma by using the water-cooled probe.

Patients & Methods: During the period from July 2002 to February 2006, fifty-one patients with osteoid osteomas localized in femur (30), tibia (9), calcaneus (2), talus (2), metatarsus (2), humerus (1), sacrum (1), scapula (1), olecranon (1), patella (1) and thoracic vertebra (1) were treated with CT-guided RF ablation using the Cooltip™ Tyco Healthcare probe. Mean age was 20 (range, 3.5 to 57) and male to female ratio was 35/16. Mean follow-up period was reported 22 months (range, 8 to 50 months). The procedures were carried out under general anesthesia and the patients were discharged from the hospital within 24 hours.

Results: Technically, all the procedures were performed successfully. Pain disappeared postoperatively in all the patients within 2–3 days and no patients needed analgesic treatment after a week. All patients were allowed fully weight bear and function without limitation after the procedure. Recurrence of the pain was observed in one patient who was treated successfully with a second ablation. Our primary and secondary clinical success rates were 98% and 100% respectively. In one case, wound infection was observed after the procedure as the only post-operative complication in our series.

Conclusion: CT-guided percutaneous RF ablation of osteoid osteomas using the water-cooled probe is a safe, effective and minimally invasive procedure with high success rate and lack of relapses.

Osteoporosis is a very common disease in the elderly, generally undertreated. Hip fracture is often the first clinical painful symptom of osteoporosis. It would seem that hip fracture should be a good opportunity to convince the patient of the importance of osteoporosis treatment. We conducted this study to check whether a simple intervention improved the compliance of osteoporosis treatment.

100 consecutive elderly patients with osteoporotic hip fracture received, during postoperative hospital stay, a 5–10 minutes long explanation about osteoporosis, its sequelae, treatment options and their effectiveness in further fracture prevention. Patients received an explanatory brochure and a letter to family physician that included a recent article on fracture rate reduction with osteoporosis treatment. Compliance was examined by telephone survey 3 and 6 months postoperatively.

100 consecutive patients with similar demographic characteristics who were treated for hip fracture prior to intervention served as a historical control. All patients received a recommendation for osteoporosis treatment in the discharge letter.

At follow up, 40% of patients in the study group were receiving biphosphonates, as opposed to 20% in the control group (p< 0.01). 77% of control patients received no treatment for osteoporosis compared to 37% of patients after intervention (p< 0.01).

Giving the patient a short explanation about osteoporosis combined with a letter to family physician, resulted in a significant improvement in their compliance The orthopaedic surgeon, who treats the patient at the first painful symptom of osteoporosis, has an excellent opportunity to improve patient’s understanding of the disease and her or his compliance to treatment.

Introduction: The common belief is that navigation-assisted TKR improves the surgical accuracy and reduces outliers, albeit increasing the operating time. We conducted a detailed study of the published studies with four main criteria:

Reduction of outliers in the placement of implants.

Methods: We performed a computerized search of the PubMed repository and a manual search of the proceedings of the International Society for Computer Assisted Orthopaedic Surgery (CAOS, 2001–05) to include all studies that presented clinical data of the results of this procedure. A total of 139 clinical studies were found, a total of 7,158 patients who underwent navigation-assisted TKR.

Results: Of the 139 studies, 39 studies presented data showing a reduction of outliers of the post-operative mechanical axis in the 180±3° range. 2,130 out of 2,401 (89%) patients operated with navigation were within this range. 27 out of the 39 studies compared the postoperative alignment of the navigated technique to that of the non-navigated technique. In the non-navigated technique, only 1,325 out of 1,880 (71%) patients were in that range, close to the published 74–75% for conventional TKR studies.

Regarding the operating time with navigation, 32 studies report an average increase of 21 min. (range 6– 48 min.), or about 20% than conventional TKR.

One of the perceived benefits of using extramedullary jigs in navigation-assisted TKR is thought to be reduction of blood loss. However, of the 15 studies that address this issue, 10 (67%) found no significant difference compared to the conventional technique. Regarding post-operative functional and/or pain scoring, 12 (80%) out of 15 studies found no statistically significant differences between navigated and non-navigated techniques.

Conclusions: The published clinical data so far shows that navigated-assisted TKR provides good alignment of the implants and a reduction of outliers from one in four to at most one in ten at the expense of 15–20 min. (about 20%) increase in operating time. No significant advantage was found for blood loss or functional/pain scoring. From a public health viewpoint, the increased cost of the navigated procedure may very well be compensated by the reduction of future revisions.

Introduction: Currently patients who had undergone lower limb arthroplasty are discharged a few days after surgery, at which stage they still need anticoagulation treatment. The transition from hospital to the community is a sensitive period and is susceptible to mistakes and misunderstandings. Patients may underestimate the importance of the continuing treatment and their inconvenience to self-administrate subcutaneous treatment might decrease their compliance. The purpose of this prospective cohort study was to investigate the continuity of the treatment with subcutaneous low molecular weight heparin at the transition period from the hospital to the community.

Materials and Methods: 209 consecutive consenting patients who had undergone lower limb arthroplasty were recruited. Ten were excluded from the study since they were subscribed oral anticoagulation; 4 patients developed pulmonary embolism and were not included, and 8 patients were lost to follow up. 187 patients were followed weekly by phone and were asked about their adherence to the daily treatment, about clinical signs suggesting a thromboembolic event and whether they sought medical assistance. Three months later there was another clinical follow up.

Results: Of the 187 patients, 174 (93%; 95% CI 88.9% < p < 96.4%) were compliant. The percentage of doctor visits by TKR patients was statistically significantly higher, (p=0.007) than by THR patients. There was no significant difference in the compliance of patients who live with their families and patients who live alone. Patients with 0–6 years of education tend to search medical advice statistically significantly more (p=0.004) than patients with more than 7 years of education.

Discussion: The rate of compliance to anticoagulation treatment with subcutaneous low molecular weight heparin was encouraging. It demonstrates that the patients understand the necessity and importance of the treatment.

Introduction: Cigarette smoking is associated with musculoskeletal degenerative disorders and increased risk of fracture delayed- and non-union. A lower-than-average concentration of mesenchymal stem cells may be the reason for the reduced regenerative potential. The aim of this study was to compare the concentration of bone marrow MSC of smokers and non-smokers.

Methods: As part of a larger IRB approved clinical trial, 20ml bone marrow samples were processed and MSC were isolated. FACS analysis was used both to assess the purity of the separation process and to evaluate the number of MSC recovered from each sample. Differences in continuous outcomes between smoking and non-smoking groups were assessed by two tailed t test and difference between categorical outcomes was measured by chi square test.

Results: Twenty six subjects participated in the study. Thirteen were smokers and thirteen were non-smokers. Groups were not significantly different with regard to age and gender. The average concentration of MSC was 352.04x10³/ml for non smokers and 131.23x10³/ml for smokers (SD’s were 245.72 x10³/ml and 161.54 x10³/ ml respectively. The difference between the smokers and nonsmokers was significant (t=3.2 p=0.004).

Discussion: The present study indicates that cigarette smokers have lower-than-average concentration of MSC in their bone marrow. Since MSC are a key element in every regenerative process of the musculoskeletal system, our findings may contribute to understanding and prevention of delayed and non-union. Further investigation is undertaken to address the issue of bone marrow recovery after smoking cessation.

Background: The purpose of this study was to analyze the applicability and advantages of the intraoperative use of a mobile isocentric C-arm with 3-dimensional imaging (SIREMOBIL ISO-C-3D) in fixation of intraarticular fractures.

Methods: Intraoperative CT-quality visualization was performed on a series of 72 closed-intraarticular fractures in 70 patients following fixation. Fracture distribution was; calcaneus (25), tibial plateau (17), tibial plafond (12), acetabulum (11), distal radius (3), ankle (3), femoral head (l). The mean patient age was 41. Intraoperative revision was performed based on the additional information Iso-C-3D provided beyond routine fluoroscopy used for fracture reduction and fixation. The primary outcome measure was revision rate after final Iso-C-3D data acquisition and prior to wound closure. Secondary objectives were to measure the additional time required for Iso-C-3D use and to determine the rate of further re-do surgeries.

Results: Eight out of 70 (11%) fracture fixations were judged by the surgeon to require intraoperative revision following Iso-C-3D imaging. In 7 cases this was due to hardware misplacement and in 1 this was for intraarticular loose fragment. Prior to leaving the operating room, the surgeon was satisfied with fracture alignment in all the procedures. The mean additional operative time using Iso-C-3D was 7.5 minutes. No patient required re-do surgery.

Conclusion: Intraoperative 3-dimensional visualization of intraarticular fractures enables the surgeon to identify inadvertent malreductions or implant malpositions which may be overlooked by routine C-arm fluoroscopy and hence eliminates the need for re-do procedures. Iso- C-3D adds little operative time and may preclude the need for preoperative and postoperative CT-scans in selected cases.

Limited access surgery is thought to reduce post-operative morbidity and provide faster recovery of function. The percutaneous compression plate (PCCP) is a recently introduced device for the fixation of intertrochanteric fractures with minimal exposure. It has several potential mechanical advantages over the conventional compression hip screw (CHS). Our aim in this prospective, randomised, controlled study was to compare the outcome of patients operated on using these two devices.

We randomised 104 patients with intertrochanteric fractures (AO/OTA 31.A1–A2) to surgical treatment with either the PCCP or CHS and followed them for one year postoperatively.

The mean operating blood loss was 161.0 ml (8 to 450) in the PCCP group and 374.0 ml (11 to 980) in the CHS group (Student’s t-test, p < 0.0001). The pain score and ability to bear weight were significantly better in the PCCP group at six weeks post-operatively. Analysis of the radiographs in a proportion of the patients revealed a reduced amount of medial displacement in the PCCP group (two patients, 4%) compared with the CHS group (10 patients, 18.9%); Fisher’s exact test, p < 0.02.

The PCCP device was associated with reduced intra-operative blood loss, less postoperative pain and a reduced incidence of collapse of the fracture.

Introduction: Cell-based strategies for regeneration and reconstitution of musculoskeletal tissues are gaining interest. The difficulty in obtaining the required amount of mesenchymal stem cells (MSC) stems from their scarcity and the time needed to grow them in culture. We developed a rapid and efficient method to isolate MSC from bone marrow aspirate based on their surface markers, as a platform for future cell based therapy.

Methods: Bone marrow was aspirated from the iliac crest of fifteen adult subjects undergoing surgeries involving this bone. 15 ml samples were obtained, fractionated for mononuclear cells and then subjected to immunomagnetic isolation using microbeads of directly conjugated mouse anti–human CD105 antibodies. Recovered cell fraction was analyzed for phenotype and functional parameters.

Results: The samples yielded an average of 14.6±2.5x10⁶ mononuclear cells per ml. Of these, fraction of CD105 positive cells consisted of 2.3±0.45%, which accounts for 0.25±0.06x10⁶ cells per ml. Post isolation analysis shows that 79±3.2% were positively stained for CD105 and 36±5.8% stained positive for CD45. These cells generated 6.3±1.4 Colony Forming Units (CFU) per 10⁵ cells. MSC concentration is higher in males and lower in smokers. Processing time is approximately 3 hours.

Discussion and Conclusion: Regeneration of mesenchymal tissues using progenitor cells with appropriate matrix and signals was shown feasible, however large numbers of these rare cells are needed. An effective and safe method for purification of autologous MSC enables us to avoid the risks and the time span associated with culture expansion. We conclude that this method is both effective and rapid.

Introduction: Fluoroscopy-based navigation systems enables surgeons to place implants with a simultaneous multi-planar monitoring. Percutaneous fixation of femoral neck fractures is an example of the growing usage of these systems in orthopedic trauma surgery. Growing evidence suggests that the accuracy of screw placement might affect the fracture outcome.

Methods: Between 2/2001 and 8/2005, 80 patients underwent internal fixation of femoral neck fractures using computerized navigation system. Three cannulated screws were implanted in an inverted triangle formation. The average patient’s age was 62±20 years (range 11–88), and 12 patients were under the age of 40 years. 53 patients were female, 27 male. 68 patients sustained the fracture due to a simple fall, 4 fell from high ground, 3-bicycle injuries, 2 due to motor vehicle accidents, and 3 patients suffered from insufficiency fractures with no trauma. The data includes results for both undisplaced fractures and fully displaced fractures which underwent closed reduction.

Results: The average length of hospital stay was 6.3±4 days (range 1–19). The average operating room time was 82±22 minutes (range 30–135), this including the preparation of the patient and instrumentation. Complications included one case of infection which necessitated long term antibiotic treatment, four patients requiring hip arthroplasty due to avascular necrosis of the femoral head, and one patient who underwent hip arthroplasty due to osteoarthritis. The total failure rate is 6%.

Conclusions: Computerized navigation for the internal fixation of subcapital femoral neck fractures allows improved screw positioning, which may reduce fracture complications, and provides reduced radiation to both the surgeon and the patient.

Introduction: Spinal fusion has become a popular surgical technique. Problems of fusion failure or pseudo-arthrosis as well as bone graft donor site complications are common. Ex vivo gene therapy using mesenchymal stem cells (MSCs) and bone morphogenetic protein (BMP) genes can provide a local supply of precursor cells and a supra-physiological dose of osteoinductive molecules that may promote bone formation and lead to spinal fusion.

Methods: Thirty 6–7 weeks old C3H/HeN immune-competent female mice received an injection of 2x10⁶ genetically engineered MSCs to the para-vertebral muscle of the lumbar spine (L2-L6) under manual palpation. Ten animals served as negative control group and 20 animals constituted the experimental group.

Bone formation in the para spinal region of the injected animals was evaluated by histology staining. Quantitative analysis of the fusion mass was monitored by micro computerized tomography (μCT).

Results: At 1, 2, 4 and 8 weeks post injection. Bone formation was extensive, as soon as the 1^st week post injection, in the area adjacent to and adhering to the posterior elements of the spine in all the study animals. None of the control animals, in which hBMP-2 was inhibited, showed any new bone formation.

Discussion: Exogenously regulated expression of the hBMP-2 enabled us to regulate bone formation in vivo, using genetically engineered MSC system. The effect of hBMP-2 in inducing bone formation was monitored in real time, non-invasive and quantitative system that enabled us to better understand the biological process during bone regeneration and repair. Our data demonstrate a regulated and monitored system for inducing bone for spinal fusion. We conclude that controlled gene therapy for spinal fusion can be achieved using Tet-regulated hBMP-2 gene and MCSs.

Introduction: To enable navigated-assisted orthopedic surgery, a reference frame must be rigidly fixed to a stable bony structure. This may create technical obstacles and wound complications. Instead, we propose to attach the reference frame to the fracture table.

Methods: The study population consisted of 10 patients who underwent fixation of subcapital femoral neck fracture with three cannulated screws, using fluoroscopy-based navigation. Step 1 – the patient was positioned on a fracture table and the reference frame was attached to the iliac crest. Three guide wires were inserted under fluoroscopy-based navigation. 2 – New fluoroscopic images were acquired. 3 – Navigated drill guide placed over each guide wire to record final navigated drill guide position – these images include actual guide wire positions and the trajectories of the navigated drill guide. Navigation accuracy was validated, measuring translational and angular deviations of the virtual trajectory from the implant on the same fluoroscopic image in anteroposterior and lateral views. 4 – The reference frame was removed from the iliac crest and attached to the fracture table. Step 3 was then repeated.

Results: The translational deviation of the virtual trajectory from the inserted guide wire when the reference frame was attached to the iliac crest was not statistically significant from the deviation when it was attached to the fracture table. Angular differences were also not statistically significant.

Conclusions: In our experience, attaching the reference frame to the fracture table instead of to the iliac crest allows for similar accuracy of the navigation process with the possible benefit of reducing patient morbidity.

Introduction Musculoskeletal injuries, especially fractures, cause reduced limb mobilization. The diminished limb activity promotes muscular atrophy, leading to a slower return to function. Attempts to prevent this atrophy using electrical stimulation have been described after knee reconstruction.

The Myospare percutaneous electrical stimulator has been developed to prevent immobilization related atrophy. We undertook this pilot study to assess feasibility, safety, and efficacy of applying electrical stimulation under a cast after ankle fractures.

Patients and Methods Between May and December 2004, patients who sustained closed ankle fractures requiring surgery, were recruited to participate in this study. 24 patients took part in the study, sixteen male and eight female. Age range was 18 to 62 years (average 40). All patients underwent open reduction and internal fixation using standard AO technique. A short walking cast was applied after surgery. Patients were randomized into a treatment and a control group. The experimental device was applied in the treatment group for 6 weeks. Patients were examined at 2, 6 and 12 weeks.

Evaluation included measurement of calf and ankle circumference, dorsiflexion and plantiflexion, and calculation of the ratio between the injured and uninjured side. At each visit pain intensity was assessed using a visual analog score, and patients filled out a function assessment questionnaire. Analysis was performed using chi square, t-test and repeated measures analysis.

Results All patients tolerated the stimulator well. No adverse effects were encountered. There is a trend toward improvement in calf diameter, dorsiflexion and plantarflexion. However, with the small number of patients in this study, no significant difference was apparent. Functional recovery and VAS scores were borderline higher in the treatment group at 12 weeks (p=0.043 and p=.049) when compared to baseline.

Discussion The use of the Myospare device under a cast in patients after surgical fixation of ankle fractures has been demonstrated as feasible and safe. In this pilot study a trend toward enhanced recovery was apparent in the treatment group.