Aims

Distraction osteogenesis (DO) is a useful orthopaedic procedure employed to lengthen and reshape bones by stimulating bone formation through controlled slow stretching force. Despite its promising applications, difficulties are still encountered. Our previous study demonstrated that pulsed electromagnetic field (PEMF) treatment significantly enhances bone mineralization and neovascularization, suggesting its potential application. The current study compared a new, high slew rate (HSR) PEMF signal, with different treatment durations, with the standard Food and Drug Administration (FDA)-approved signal, to determine if HSR PEMF is a better alternative for bone formation augmentation.

Segmental bone transport (SBT) with an external fixator has become a standard method for treatment of large bone defect. However, a long time-application of devices can be very troublesome and complications such as nonunion is sometimes seen at docking site. Although there have been several studies on SBT with large animal models, they were unsuitable for conducting drug application to improve SBT. The purpose of this study was to establish a bone transport model in mice. Six-month-old C57BL/6J mice were divided randomly into bone transport group (group BT) and an immobile control group (group EF). In each group, a 2-mm bone defect was created in the right femur. Group BT was reconstructed by SBT with external fixator (MouseExFix segment transport, RISystem, Switzerland) and group EF was fixed simply with unilateral external fixator (MouseExFix simple). In group BT, a bone segment was transported by 0.2 mm per day. Radiological and histological studies were conducted at 3 and 8 weeks after the surgery. In group BT, radiological data showed regenerative new bone consolidation at 8 weeks after the surgery, whereas high rate of nonunion was observed at the docking site. Histological data showed intramembranous and endochondral ossification. Group EF showed no bone union. In this study, experimental group showed good regenerative new bone formation and was similar ossification pattern to previous large animal models. Thus, the utilization of this bone defect mice model allows to design future studies with standardized mechanical conditions for analyzing mechanisms of bone regeneration induced by SBT

Aims

Loosening is a well-known complication in the fixation of fractures using devices such as locking plates or unilateral fixators. It is believed that high strains in the bone at the bone-screw interface can initiate loosening, which can result in infection, and further loosening. Here, we present a new theory of loosening of implants. The time-dependent response of bone subjected to loads results in interfacial deformations in the bone which accumulate with cyclical loading and thus accentuates loosening.

Objectives. External fixators are the traditional fixation method of choice for contaminated open fractures. However, patient acceptance is low due to the high profile and therefore physical burden of the constructs. An externalised locking compression plate is a low profile alternative. However, the biomechanical differences have not been assessed. The objective of this study was to evaluate the axial and torsional stiffness of the externalised titanium locking compression plate (ET-LCP), the externalised stainless steel locking compression plate (ESS-LCP) and the unilateral external fixator (UEF). Methods. A fracture gap model was created to simulate comminuted mid-shaft tibia fractures using synthetic composite bones. Fifteen constructs were stabilised with ET-LCP, ESS-LCP or UEF (five constructs each). The constructs were loaded under both axial and torsional directions to determine construct stiffness. Results. The mean axial stiffness was very similar for UEF (528 N/mm) and ESS-LCP (525 N/mm), while it was slightly lower for ET-LCP (469 N/mm). One-way analysis of variance (ANOVA) testing in all three groups demonstrated no significant difference (F(2,12) = 2.057, p = 0.171). There was a significant difference in mean torsional stiffness between the UEF (0.512 Nm/degree), the ESS-LCP (0.686 Nm/degree) and the ET-LCP (0.639 Nm/degree), as determined by one-way ANOVA (F(2,12) = 6.204, p = 0.014). A Tukey post hoc test revealed that the torsional stiffness of the ESS-LCP was statistically higher than that of the UEF by 0.174 Nm/degree (p = 0.013). No catastrophic failures were observed. Conclusion. Using the LCP as an external fixator may provide a viable and attractive alternative to the traditional UEF as its lower profile makes it more acceptable to patients, while not compromising on axial and torsional stiffness. Cite this article: B. F. H. Ang, J. Y. Chen, A. K. S. Yew, S. K. Chua, S. M. Chou, S. L. Chia, J. S. B. Koh, T. S. Howe. Externalised locking compression plate as an alternative to the unilateral external fixator: a biomechanical comparative study of axial and torsional stiffness. Bone Joint Res 2017;6:216–223. DOI: 10.1302/2046-3758.64.2000470

A retrospective study was performed in 18 patients with achondroplasia, who underwent bilateral humeral lengthening between 2001 and 2013, using monorail external fixators. The mean age was ten years (six to 15) and the mean follow-up was 40 months (12 to 104).

The mean disabilities of the arm, shoulder and hand (DASH) score fell from 32.3 (20 to 40) pre-operatively to 9.4 (6 to 14) post-operatively (p = 0.037). A mean lengthening of 60% (40% to 95%) was required to reach the goal of independent perineal hygiene. One patient developed early consolidation, and fractures occurred in the regenerate bone of four humeri in three patients. There were three transient radial nerve palsies.

Humeral lengthening increases the independence of people with achondroplasia and is not just a cosmetic procedure.

Cite this article: Bone Joint J 2015;97-B:1577–81.

Although gradual bone transport may permit the restoration of large-diameter bones, complications are common owing to the long duration of external fixation. In order to reduce such complications, a new technique of bone transport involving the use of an external fixator and a locking plate was devised for segmental tibial bone defects.

A total of ten patients (nine men, one woman) with a mean age at operation of 40.4 years (16 to 64) underwent distraction osteogenesis with a locking plate to treat previously infected post-traumatic segmental tibial defects. The locking plate was fixed percutaneously to bridge proximal and distal segments, and was followed by external fixation. After docking, percutaneous screws were fixed at the transported segment through plate holes. At the same time, bone grafting was performed at the docking site with the external fixator removed.

The mean defect size was 5.9 cm (3.8 to 9.3) and mean external fixation index was 13.4 days/cm (11.8 to 19.5). In all cases, primary union of the docking site and distraction callus was achieved, with an excellent bony result. There was no recurrence of deep infection or osteomyelitis, and with the exception of one patient with a pre-existing peroneal nerve injury, all achieved an excellent or good functional result.

With short external fixation times and low complication rates, bone transport with a locking plate could be recommended for patients with segmental tibial defects.

Cite this article: Bone Joint J 2013;95-B:1667–72.

The October 2012 Trauma Roundup³⁶⁰ looks at: which patients die from pelvic ring fractures; monolateral distraction osteogenesis; surgical management of pelvic and peroneal blast injuries; weekend warriors at risk of going AWOL; early experience with the locking attachment plate; and fibula nailing - an alternate, and viable technique.

We report the outcome of 32 patients (37 knees) who underwent hemicallostasis with a dynamic external fixator for osteoarthritis of the medial compartment of the knee. There were 16 men (19 knees) and 16 women (18 knees) with a mean age at operation of 54.6 years (27 to 72). The aim was to achieve a valgus overcorrection of 2° to 8° or mechanical axis at 62.5% (± 12.5%). At a mean follow-up of 62.8 months (51 to 81) there was no change in the mean range of movement, and no statistically significant difference in the Insall-Salvati index or tibial slope (p = 0.11 and p = 0.15, respectively). The mean hip-knee-ankle angle changed from 190.6 (183° to 197°) to 176.0° (171° to 181°), with a mean final position of the mechanical axis of 58.5% (35.1% to 71.2%).

The desired alignment was attained in 31 of 37 (84%) knees. There were 21 excellent, 13 good, two fair and one poor result according to the Oxford knee score with no correlation between age and final score. This score was at its best at one year with a statistically significant deterioration at two years (p = 0.001) followed by a small but not statistically significant deterioration until the final follow-up (p = 0.17). All the knees with Ahlback grade 1 osteoarthritis had excellent or good results. Complications included pin tract infections involving 16.4% of all pins used, delayed union in two, knee stiffness in four, fracture of the lateral cortex in one and ring sequestrum in one.

In conclusion, hemicallostasis provides precision in attaining the desired alignment without interfering with tibial slope or patellar height, and is relatively free of serious complications.

The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) for the treatment of congenital pseudarthrosis of the tibia has been investigated in only one previous study, with promising results. The aim of this study was to determine whether rhBMP-2 might improve the outcome of this disorder. We reviewed the medical records of five patients with a mean age of 7.4 years (2.3 to 21) with congenital pseudarthrosis of the tibia who had been treated with rhBMP-2 and intramedullary rodding. Ilizarov external fixation was also used in four of these patients. Radiological union of the pseudarthrosis was evident in all of them at a mean of 3.5 months (3.2 to 4) post-operatively. The Ilizarov device was removed after a mean of 4.2 months (3.0 to 5.3). These results indicate that treatment of congenital pseudarthrosis of the tibia using rhBMP-2 in combination with intramedullary stabilisation and Ilizarov external fixation may improve the initial rate of union and reduce the time to union.

Further studies with more patients and longer follow-up are necessary to determine whether this surgial procedure may significantly enhance the outcome of congenital pseudarthrosis of the tibia, considering the refracture rate (two of five patients) in this small case series.

The results of the treatment of 31 open femoral fractures (29 patients) with significant bone loss in a single trauma unit were reviewed. A protocol of early soft-tissue and bony debridement was followed by skeletal stabilisation using a locked intramedullary nail or a dynamic condylar plate for diaphyseal and metaphyseal fractures respectively. Soft-tissue closure was obtained within 48 hours then followed, if required, by elective bone grafting with or without exchange nailing.

The mean time to union was 51 weeks (20 to 156). The time to union and functional outcome were largely dependent upon the location and extent of the bone loss. It was achieved more rapidly in fractures with wedge defects than in those with segmental bone loss. Fractures with metaphyseal defects healed more rapidly than those of comparable size in the diaphysis. Complications were more common in fractures with greater bone loss, and included stiffness of the knee, malunion and limb-length discrepancy.

Based on our findings, we have produced an algorithm for the treatment of these injuries. We conclude that satisfactory results can be achieved in most femoral fractures with bone loss using initial debridement and skeletal stabilisation to maintain length, with further procedures as required.

We present the results of 13 patients who suffered severe injuries to the lower leg. Five sustained a traumatic amputation and eight a Gustilo-Anderson type IIIC open fracture. All were treated with debridement, acute shortening and stabilisation of the fracture and vascular reconstruction. Further treatment involved restoration of tibial length by callus distraction through the distal or proximal metaphysis, which was commenced soon after the soft tissues had healed (n = 8) or delayed until union of the fracture (n = 5).

All patients were male with a mean age of 28.4 years (17 to 44), and had sustained injury to the leg only. Chen grade II functional status was achieved in all patients. Although the number of patients treated with each strategy was limited, there was no obvious disadvantage in the early lengthening programme, which was completed more quickly.

What was the question? The treatment of multi-injured patients requires initial stabilization of general conditions and vital parameters. The first stage in orthopedic management of the fractures in trauma involves stabilization of the bone segments to reduce blood loss and allow nursing. External fixators are fast, versatile and essential in the emergency situation in cases of multiple fractures, especially with soft tissue loss. According to damage control orthopedics (DCO) concepts, it is possible to replace an external fixator (EF) with internal synthesis (ORIF) after a period of time to reduce the risks of ORIF. However, surgery can be difficult to perform and pin sites can be the source of bone infection, in which the EF as a definitive treatment option may be considered. How did you answer the question? In trauma surgery, instability of the hardware, fractures near the joint, frame extending across the knee and the ankle, initial fixation was converted to definitive treatment with circular frames according to the Ilizarov method. Fourteen patients (2 female and 12 males; age 24 to 80 yrs, average age 43,4 y/o) were treated with various circular framses as definitive treatment: Ilizarov (2), Sheffield (7), Taylor Spatial Frame (TSF) (4) and TrueLok (1) between November 2002 and December 2007 in multiply injured patients with ISS > 20. Seven cases were femoral and seven tibial. The femoral group had four knee spanning fixator configurations and three unilateral external fixators. The tibial group had 4 unilateral frames, 1 hybrid EF, 1 across the knee EF and 1 across the ankle EF. Five patients had temporary femoral and tibial hardwares in the same side. Three patients had unilateral tibial and femoral fractures. What are the results? All patients achieved consolidation. The mean duration of femoral EF was 7.6 months (5–9 months). One bone loss in a distal femoral shaft treated with Sheffield EF had lengthening (5 cm) after acute short-hening. Two patients had a gradual distal femoral fracture reduction and a mechanical axis correction by TSF. Three patients with tibial bone loss had 2 trifocal bone transport (17,5 and 9 cm) and 1 bifocal bone transport 5 cm. The TSF had no additional pre-operative planning and major post-operative frame adjustments. The intra-operative devices was easier for the TSF. What are your conclusions? Circular frame osteosynthesis following initial EF, is a reliable and effective strategy for treatment in severe open femur and tibia fractures and post traumatic reconstruction

Background: The occurrence of congenitally short metatarsals is associated with an abnormal gait and an aesthetically displeasing appearance. Similarly, short metacarpals result in severe cosmetic disfigurement, particularly in young female patients. Methods: We examined and performed bone lengthening surgery in 13 female and 2 male patients. Of these, procedures were conducted on 12 metatarsals of 8 patients, 4 metacarpals and 1 metatarsal of a single patient, 1 metacarpal and 1 metatarsal of a single patient and 7 metacarpals of 5 patients. The mean age of the patients who underwent metacarpal procedures was 14.5 (10–21) years while the mean age of those who underwent metatarsal procedures was 17.5 (10–25) years. The callotasis method was employed for these procedures and we used either a unilateral external fixator and/or a circular external fixator. Results: The mean healing index and increase in metacarpal length was 1.6 (1.1–2.3) months/cm and 17.6 (13–26) mm, respectively. The mean follow-up period for patients who underwent metacarpal lengthening was 57.5 (12–96) months. The mean healing index and increase in metatarsal length was 1.6 (1.0–2.0) months/cm and 24.3 (20–30) mm respectively. The mean follow-up period for patients who underwent metatarsal lengthening was 48.3 (12–72) months. The preoperative AOFAS (American Orthopaedic Foot and Ankle Society) scores were good in 5 and excellent in 9 cases. The functional scores of metatarso-phalangial (MTP) joint of lengthened metatarsals for the lesser toe were excellent in 12 and good in 2 cases based on the AOFAS scoring system. All patients who underwent metacarpal lengthening reported that they were satisfied and could conduct their daily activities with good functional and aesthetic results. Complications included 4 angulations, 1 subluxation and 1 non-union and were seen in 6 of the metatarsal lengthening cases that exceeded 40% (or > 20 mm) of the total length of the original bone. Interpretation: There are recommendations in the literature that allow for the avoidance of severe complications and for the shortening of the consolidation period. We conclude that the periosteum must be protected with percutaneus osteotomy and lengthening should be performed at a rate of 0.25 mm twice a day, should not exceeding 40% of the original bone length (or > 20 mm). If the anticipated lengthening exceeds these predefined values then we suggest that the procedure should be performed using a circular external fixator with temporary fixation of the MCP or the MTP joint and the inclusion of the proximal phalanx in the frame

Purpose: We reviewed all isolated tibial shaft fractures treated by operative means, with focus on prolonged healing and infection. Design; Retrospective Case Control Study; level of evidence; Prognostic level III. Methods: Patients: 821 isolated tibial shaft fractures, with a drop-out of 5.6% Open fractures: 400 (grade I & II 280, grade IIIa,b,c 120) Type A,B fractures: 597 Type C fractures: 224 Skeletal Fixation Modes: Ex;Fix (unilateral-one plane): 192, UTN(Synthes): 337, Plate(LCDCP): 129, RTN(Synthes): 163. Outcome measurements: Union time, requirement for secondary treatment, and development of deep infection. Results: Infections: 94 (11,4%), Closed # which became infected: 21 (5%) Open # which became infected: 73 (18%) Ex.Fix: 56 (29%) Plate: 15 (12%) UTN: 16 (5%) RTN: 7 (5%) In a multiple logistic regression analysis, only Soft tissue damage had a statistical significant interference with the outcome infection (point estimate 0.117, 95% CI 0.053–0.262) Prolonged healing: 285 (34%)? Delayed union 191 ? Non-union 94 Closed fractures which develop a delayed healing: 56 (13%) Open fractures which develop a delayed healing: 135 (34%) Closed fractures which develop a non-union: 20 (5%) Open fractures which develop a non-union: 74 (19%) In a multiple logistic regression analysis, infection & fracture type had a statistical significant interference with the outcome prolonged healing. Conclusions: The use of an unilateral external fixator as a definitive treatment for tibial fractures is obsolete. For a contaminated tibial fracture the use of the UTN diminish the risk of infection. Looking for the healing time, UTN & Ex.Fix. are associated with a significant prolonged bone healing time

To report the results of the intramedullary skeletal kinetic distractor (iskd) in patients with established leg length discrepancy following lower limb trauma. 12 patients with significant leg length discrepancy (> 20mm) following lower limb trauma were operated on using the iskd nail between september 2004 and december 2007. patients were followed up clinically and radiologically at minimum 18 months (mean: 27months range: 18–24 months). 8 femurs and 4 tibias were operated using the iskd nail. all patient in the series had successful completed treatements. the average leg length discrepancy was 38mm (91mm–21mm) and the average gained length was 37mm (76m–22mm). radiological union and bone consolidation were slow to occur. early weight bearing was permitted allowing earlier functional capacity. 6 patients required additional operations; 3 manipulation under anaesthesia for failed lengthening and 3 bone grafting for poor regenerate, 1 patient required more than one additional operation. The iskd nail is an effective and reliable alternative technique for correcting leg length discrepancy in patients who have suffred lower limb trauma. it appears to mimic the results achieved with the use of a fine wire external fixator or a unilateral external fixator. the convenience of a fully implanted device is substantial. the complications are frequent but manageable with standard techniques

Introduction: Pin loosening is a common complication associated with external fixation. Various attempts such as coating the pins with calcium phosphates, have been made to modify the pin surface in order to reduce pin loosening and provide good fixation. Animal and clinical studies showed that fixation using tapered external fixation pins coated with hydroxyapatite is superior to standard pins. However, there is no data on cylindrical pins either fully or partially coated with HA. A partial coating could be a solution to optimize pin fixation with the advantage of easier removal compared to fully coated pins. Our purpose was to compare standard and partially coated cylindrical Apex pins implanted in a sheep model at 2 and 6 weeks. As controls we included fully coated tapered pins. Materials/Methods: Five groups of pins were studied. Group A included standard cylindrical Apex pins implanted in sheep which were euthanized 2 weeks after surgery; Group B included partially coated Apex pins implanted in sheep which were euthanized 2 weeks after surgery; Group C included tapered pins fully coated with HA implanted in sheep which were euthanized 2 weeks after surgery; Group D included Standard Apex pins implanted in sheep which were euthanized 6 weeks after surgery; Group E included partially coated Apex pins implanted in sheep which were euthanized 6 weeks after surgery. With the tapered pins, full contact between the coated surface and both cortices was obtained. After pin implantation, a unilateral external fixator was mounted onto the pins (Stryker carbon blue monotube Ø 20/250mm). A 5mm long removal osteotomy was performed in the mid-part of the tibial diaphysis, so that 3 pins were situated above the gap and 3 below to ensure load transfer through the bone-pin interface. Extraction torque and tibial torque resistance and histological analyses were obtained after pin removal. Results: At 2 weeks, mean insertion torque was significantly higher for group C compared to group A (p = 0.03). Mean extraction torque was statistically higher for group B compared to group A (p = 0.001). A statistically significant difference was found in the Pettine index (p = 0.03) between groups A and B. At 6 weeks, no differences in extraction torque were seen. Discussion: We believe that the partial application of the coating reduced the potential for osteointegration and the ultimate fixation of the coated Apex pins

We report the results of using a combination of fixator-assisted nailing with lengthening over an intramedullary nail in patients with tibial deformity and shortening. Between 1997 and 2007, 13 tibiae in nine patients with a mean age of 25.4 years (17 to 34) were treated with a unilateral external fixator for acute correction of deformity, followed by lengthening over an intramedullary nail with a circular external fixator applied at the same operating session. At the end of the distraction period locking screws were inserted through the intramedullary nail and the external fixator was removed. The mean amount of lengthening was 5.9 cm (2 to 8). The mean time of external fixation was 90 days (38 to 265). The mean external fixation index was 15.8 days/cm (8.9 to 33.1) and the mean bone healing index was 38 days/cm (30 to 60). One patient developed an equinus deformity which responded to stretching and bracing. Another developed a drop foot due to a compartment syndrome, which was treated by fasciotomy. It recovered in three months. Two patients required bone grafting for poor callus formation. We conclude that the combination of fixator-assisted nailing with lengthening over an intramedullary nail can reduce the overall external fixation time and prevent fractures and deformity of the regenerated bone

Ring frames have the advantage of allowing progressive correction. However, the available frames for complex deformities are heavy and bulky leading to poor compliance by patients. Also, the mounting procedure requires considerable expertise and skill. On the other hand, a unilateral external fixator has the advantages of less bulk and a lighter weight. Thus, it causes less disability and can achieve better patient compliance even with bilateral application. However, previous unilateral fixators have had various limitations with respect to deformity correction, such as restricted placement of hinges, restricted correction planes, and a limited range of correction angles. In addition, it was impossible to achieve progressive correction while fixation was maintained. To overcome these disadvantages of existing unilateral fixators, we developed a new fixator for gradual correction of multi-plane deformities including translational and rotation deformities. This unilateral external fixator is equipped with a universal bar link system. The link is constructed from three dials and two splines that are connecting the dials. The pin clamps are able to vary the direction of a pin cluster in the three dimensional planes. The system allows us to correct angulation, translation, rotation, and the combination of the above. In addition, open or closed hinge technique is available because the correction hinge can be placed right on the center of rotational angulation (CORA), or at any desired location, by adjusting the length of the link spline. By increasing the spline length, the virtual hinge can also be set far from the fixator. Gradual correction can be performed by rotating the three dials using a worm gear goniometer that is temporarily attached. A 3D reconstructed image of the bone is generated preoperatively. Preoperative planning can be done using this image. Mounting parameters are determined by postoperative AP and lateral computed radiography images. These postoperative images are matched with the pre-operative 3D CT image by 2D and 3D image registration. Then, the fixator can be virtually fixed to the bone. By performing virtual correction, it is possible to plan the correction procedure. The fixator is manipulated by rotating each of the three dials to the predetermined angles calculated by the software. Static load testing disclosed that the fixator could bear a load of 1700 N. No breakage or deformation of the fixator itself was recognized. Mechanical testing demonstrated that this new fixator has sufficient strength for full weight bearing, as well as sufficient fatigue resistance for repeated or prolonged use. The results of clinical application in patients with multi-plane femoral deformities were excellent, and correction with very small residual deformity was achieved in each plane

PURPOSE: There is an argument in the literature regarding the use of intramedullary nail or the external fixation followed by intramedullary nail in tibial fractures with severe damage of soft tissues, threatened compartment syndrome, open type IIIA fractures and in polytrauma patients. The purpose of this retrospective study was to evaluate the results of non-jointed external fixators as a definite treatment for these type of tibial shaft fractures. MATERIAL AND METHOD: 86 patients (91 tibial shaft fractures) were treated at the authors’ institute with a non-jointed external fixator. The mean patient age was 35 years (range, 15–80). There were 70 male and 16 female patients. The average time of surgery from the accident was 10 hours. The indications for application an external fixator was: severe damage of the soft tissues in 11 fractures, an incipient compartment syndrome in 12 fractures, open type III Gustilo fractures in 57, and 11 tibia fractures in polytrauma patients. According to AO classification 46 fractures were type A, 32 type B and 13 type C. RESULTS: The average follow up was 2.9 years (ranged, 1–5 years). The average operative time was 50 min. Complications included: 3 non-unions, 5 delayed unions, 1 malunions, 1 tibia shortening, 3 superficial infections of soft tissues in open fractures, 26 pin infections and 1 osteomyelitis in open fractures. In 2 patients fat embolism was diagnosed while pulmonary embolism was a complication in 2 patients. Deep venous thrombosis (DVT) developed in 5 patients. A re-operation was performed in 11 out of 91 fractures. Change of the method was necessary in 2 out of 91 fractures. The primary callus in 10 out of 91 fractures was due to the stiffness of the unilateral non-jointed external fixators and did not influence the final results. Mean time of fracture union for the open fractures that did not require change of the method nor bone graft was 25 weeks, while for the closed fractures was 18 weeks. The dynamization of the system and partial weight bearing was started at 6 weeks and all the patients had full weight bearing by the 12th week. CONCLUSION: The unilateral external fixators were the definite treatment in 88 out of 91 fractures. The unilateral external fixators can be used as a definite treatment for tibial shaft fractures in the majority of the cases. Re-operation or change of the method is unusual and must be performed only when there is a delay in callus formation

Background & Objectives: Osteoporosis is one of the most prevalent bone diseases worldwide with fractures its major clinical consequence. Studies on the effect of osteoporosis on fracture repair are contradictory and although it might be expected for fracture repair to be delayed in osteoporotic individuals, a definitive answer still eludes us. Subsequently, the aim of this study was to attempt to clarify any such effect. Methods: Osteoporosis was induced in 53 female Sprague-Dawley rats by ovariectomy (OVX) at 3 months. A femoral fracture was produced in these animals 12 weeks later {OVX+Fracture group (OVX+F)}. A control group received the fracture only group (F) at 6 months. The fracture consisted of an open osteotomy held with a unilateral external fixator. Outcome measures include histology, motion detector analysis, pQCT, biomechanical strength testing (BST) and digital radiography. Digital radiographs were taken at time of OVX, fracture (confirming satisfactory reduction) and sacrifice from which relative bone density (BMD) measurements were calculated. Results: OVX+F animals were significantly heavier than F animals at fracture and sacrifice (p< 0.001 for both) and moved significantly less in days 1-4 (p=0.032) and 5-9 (p=0.020) post-fracture. Relative BMD measured in distal femur at fracture and sacrifice was significantly greater in F group (p< 0.001 for both). Furthermore, there was a significant decrease in relative BMD from fracture to sacrifice in OVX+F group (p< 0.001). pQCT showed a significantly greater total BMD {contralateral (p=0.021) and fractured femora (p< 0.001)} and trabecular BMD (p< 0.001 both limbs) in the distal femur of the F group. Histologically, no statistical differences were found, however, the F group generally displayed the most advanced repair. In the contralateral limb, the F group had significantly greater load to failure at 6 (p=0.026) and 8 (p=0.042) weeks and was significantly stiffer at 8 weeks (p=0.050). In the fractured leg, stiffness was significantly greater in the F group at 8 weeks (p=0.001). Conclusion: OVX was linked to increased body weight, decreased motion, decreased BMD (with particular loss in trabecular BMD), and reduced mechanical properties. OVX did not have a significant effect on fracture healing and although there was no reduction in BMD at the fracture site, histology and reduced stiffness suggest it was delayed