Half Pins Research Articles

Safety and Complication Rate of Ring External Fixation in the Foot and Ankle

External fixation is a powerful tool for foot and ankle surgeons. Currently, there is no consensus on true complication rate. The purpose of this study was to report our institution's complication rate of ring external fixation performed by a single surgeon. We retrospectively evaluated electronic medical record of 224 patients with 238 circular frames between 2009 to 2021 at a single institution. We defined minor complications as a frame managed without early frame removal or return to operating room. Major complications were defined as early return to operative room or early removal defined by our institution as less than two months. We recorded over 1,642 Ilizarov wires and 278 half pins; 10% (n=163) of wires and 7% (n=19) of half pins had a complication. We recorded 44% (n=104) minor complications and 9% (n=22) major complications. Minor complications average (mean) onset was four weeks, 89% (n=93) involved wires, and 73% resolved without additional care. Major complications average (mean) onset was 3.7 weeks. Of these, 32% (n=7) went on to successful revision. This revealed a significant correlation between minor complications and history of osteomyelitis (p<0.05). While minor complications do appear high, we find this was due to wire irritation and local erythema which resolved without additional intervention. To better assess complications with external fixation we believe that wire irritation and pin site erythema should be recognized as an expected outcome. A better understanding of ring external fixation in foot and ankle surgery is vital to appropriate perioperative management and patient care. Clinical level of Evidence: IV, retrospective chart review.

Minimal invasive mini-rail external fixation for surgical treatment of calcaneal fractures

The purpose of this study is to evaluate and promote the application of percutaneous minimal invasive uniplanar mini-rail external fixation for definitive fixation for displaced calcaneal fractures. This technique has been promoted to avoid soft tissue complications commonly seen with calcaneal open reduction internal fixation, and allows to apply skeletal traction and fracture reduction through ligamentotaxis with percutaneous fixation of the posterior facet fragments without the need to delay surgery secondary to edema. ​In this retrospective study, application of four 3.0mm stainless steel partially threaded half pins were applied across an intra-articular calcaneal fracture, 2 proximal and two distal, allowing for longitudinal traction and stabilization following reduction. Clinical outcomes were determined with a minimal 12-month follow up and a American Orthopedic Foot and Ankle Score (AOFAS) hindfoot score questionnaire. We evaluated and surgically managed 21 patients who presented to the emergency department with closed calcaneal fractures in a 6-year period, beginning from the year 2014 to 2020 with mini-rail fixation. Of the 21 patients, 12 (57%) participated in this study and were also evaluated by physical examination. Regarding patient satisfaction with minimal invasive percutaneous mini-rail fixation, patients reported an average AOFAS score of 82.1, 91% (11/12 patients) and were able to return to work, and only 1 patient required an additional surgery. The clinical results are comparable with traditional open reduction internal fixation with no soft tissue disruption, avoidance of internal fixation plates/screws, and allows for early mobilization.

Avoiding iatrogenic vascular injury in tibial external fixation with half pins. An in-vivo study based on CT angiography

BackgroundExternal fixation is an important tool in the management of variety of tibial fractures. Appropriate half pin insertion is important, to provide stable fixation without compromising the surgical field for definitive surgical procedures, and avoiding further damage to the important structures of the traumatized limb. There is paucity of literature about the optimal trajectories and safe corridors for half pins insertion based on in vivo studies. The available studies are based on anatomic atlases, cadaveric studies or half pin related complications.The aim of the current study is to present the findings of CT angiograms, in patients with external fixation of tibia, to enhance our understanding of optimal trajectories in safe corridors for half pins insertion. Material and methodsWe performed a retrospective study of patients with external fixators on the tibia, who had undergone CT angiogram as part of pre-operative planning for orthoplastic reconstructive procedures. The relationship between the tips of the fixator half pins and named vessels of the leg were analyzed, pins within 5 mm of a named vessel were considered to be a risk of causing iatrogenic injury. ResultsA total 51 patients, with in situ temporizing external fixators, with 134 half pins in different segments of the tibia were analyzed. More than 5 mm of penetration beyond the far cortex was noted in 47%, while in another 16% of pins penetration was more than 10 mm beyond the cortex. A tip to vessel distance (TVD) of 5 mm or less was noted in 28/134 (21%) of the pins, which highlights potential risk to the neurovascular bundles of the leg. ConclusionRisk of iatrogenic injury to neurovascular structures from half pin insertion can be reduced by meticulous use of fluoroscopy, by avoiding penetration beyond the far cortex, and avoiding exiting with half pins on the lateral surface in the distal 1/3rd of segment II of tibia. Moreover observing optimal trajectories and safe corridors for pin insertion, and selection of appropriate type of half pin can mitigate the risk to these structures.

Safety of Tibial Half Pins With Circular External Fixation for Foot and Ankle Reconstruction in Patients With Peripheral Neuropathy

The primary aim of the study was to evaluate the rate of tibial fracture with half pin placement in conjunction with tensioned wires in Ilizarov static external fixator in patients with peripheral neuropathy. Concentric visualization through a rancho cube and careful identification of anterior, posterior, medial, and lateral borders of the tibia, the “perfect circle” technique was used to ensure avoidance of cortical breach. Bivariate analysis was performed comparing the rates of tibia fractures in those who did and did not employ the “perfect circle” technique for placement of tibial half pins; evaluating for demographics, rationale for external fixation use, and postoperative amputation and complication rates. Tibial stress fractures, and early removal of pin/wires from external fixator secondary to breakage both occurred at statistically significant higher rates in patients in which the “perfect circle” technique was not employed (p < .001 and p = .03 respectively). The overall rate of tibia stress fractures was 2.08% (2/96), 0% (0/85) when “perfect circle” technique was used, compared to 18.18% (2/11) when it was not used. This study demonstrates a substantially low rate of tibia stress fractures with half pin use, in contrast to prior literature and should provide foot and ankle surgeons confidence, particularly when appropriate placement is observed in this high-risk population.

Role of the Ilizarov fixator in high tibial osteotomy

Role of the Ilizarov fixator in high tibial osteotomy

The reuse of circular external fixator components: an assessment of safety and potential savings.

Cost-saving strategies are important, especially in a resource-constrained environment. One such strategy well supported in the literature is the reuse of temporary monolateral external fixator components, a strategy we utilize at our institution. The aim of the study was to determine the safety and cost saving associated with the reuse of definitive circular external fixator components in a resource-constrained environment. We performed a retrospective review of all adult patients who were treated with either new or reused circular external fixators from a single manufacturer between January and December 2017. Reused circular external fixator components, excluding half pins and wires, were subjected to an in-house reprocessing protocol. Cost savings were calculated as the difference between the price of a completely new frame and the amount invoiced for new components only in a reused frame. Thirty-three patients were included in the study with an average age of 31.9years. The mean duration of treatment with a circular external fixator was 5.8months. No mechanical failure events were recorded during the study period. Our institution saved approximately 52% (R717 503.89) and 63% (R136 568.19) of expected total cost for hexapod and Ilizarov frames, respectively. The strategy of reusing circular external fixator components is unconventional, and this study was conducted to evaluate the safety and potential savings in a resource-constrained environment. We demonstrated this practice to be reasonably safe and to result in significant cost savings which might be relevant in low-and-middle-income countries.

The skin biopsy punch: a novel technique for half pin site incisions in circular frame application.

The skin biopsy punch: a novel technique for half pin site incisions in circular frame application.

Optimal time-dependent levels of weight-bearing for bone fracture healing under Ilizarov circular fixators

It is known that weight-bearing exercises under Ilizarov circular fixators (ICF) could enhance bone fracture healing by mechano-regulation. However, interfragmentary movements at the fracture site induced by weight-bearing may inhibit angiogenesis and ultimately delay the healing process. To tackle this challenge, a computational model is presented in this study which considers the spatial and temporal changes in mechanical properties of fracture callus to predict optimal levels of weight-bearing during fracture healing under ICF. The study takes sheep fractures as example and shows that the developed model has the capability of predicting patient specific, time-dependent optimal levels of weight-bearing which enhances mechano-regulation mediated healing without hindering the angiogenesis process. The results demonstrate that allowable level of weight-bearing and timings depend on fracture gap size. For normal body weights (BW) and moderate fracture gap sizes (e.g. 3 mm), weight-bearing with 30% BW could start by week 4 post-operation and gradually increase to 100% BW by week 11. In contrast, for relatively large fracture gap sizes (i.e. 6 mm), weight-bearing is recommended to commence in later stages of healing (e.g. week 11 post-operation). Furthermore, increasing ICF stiffness (e.g. using half pins instead of pretension wires) can increase the level of weight-bearing significantly in the early stages up to a certain time point (e.g. week 8 post-operation) beyond which no noticeable benefits could be achieved. The findings of this study have potential applications in designing post-operative weight bearing exercises.

Management of Infected Charcot Neuroarthropathy due to Diabetes Mellitus with Half Pins External Fixator and Pinning: A Case Series

BACKGROUND: Charcot neuroarthropathy (CN) of the foot and ankle, which is complicated with infection, is debilitating disease and presents challenges until now. External fixation with half-pins is useful as provisional treatment.&#x0D; AIM: The purpose of this retrospective case series is to summarize the patient characteristic, type of surgical intervention, outcome, and complication of infected CN treated in our hospital.&#x0D; MATERIALS AND METHODS: This case series studied retrospectively patients with CN of the foot and ankle due to diabetes mellitus type II, complicated by infection, who required surgical treatment in a single institution, from 2018 to 2019. Diagnosis was based on chronic deformity (fracture or dislocation) as proven on X-ray and recently developed infection as shown through clinical, laboratory, and radiological evaluation.&#x0D; RESULTS: We studied seven patients with CN classified as Eichenholtz Stage 3 (100%) and Brodsky type 3A alone (n = 3) (Figure 1), and type 3A with other types (n = 4). The mean age is 44.6 years old (range, 35–60) and mean body mass index was 24.08 kg/m2 (range, 21.45–25.39). Signs of infection include leukocytosis (n = 6), soft-tissue swelling (n = 4), ulcer (n = 4), and osteomyelitis (n = 1) at presentation. Operative treatment consisted of debridement, followed by external fixation only (n = 4), combined external fixation and pinning (n = 2), and intramedullary pinning only (n = 1). The mean hospital length of stay was 4.5 days (range, 3–7). We performed short-term follow-up after a mean of 4.12 months (range, 1.3–5.3) and long-term after a mean of 15.02 months (range, 11.27–16.8), the limb salvage rate was 100% in both. One patient had revision of external fixation. As for functional outcome, at the time of long-term follow-up mean visual analogue scale was 0.75 (range, 0–2) and American Orthopaedic Foot and Ankle Score was 66.25 (range, 57–77).&#x0D; CONCLUSION: In this study, mostly external fixation with half-pins and methyl metacrylate was used based on the bone condition and patient’s compliance. Despite of its limitation, this method is effective when it is combined with strict blood glucose level and infection control.

Correction outcomes of the postoperative malalignment salvaged by the temporary application of the hexapod external fixator in tibial diaphyseal fractures treated by monolateral external fixation

BackgroundPostoperative malalignment in fractures treated by monolateral external fixation is not uncommon in clinical practice. Accurate reduction without excessive tissue disruption caused by surgical intervention and sequentially manage the fractures using monolateral external fixation for definitive treatment is still a challenge for surgeons. The purpose of our study was to evaluate the feasibility and effectiveness of the temporary application of the hexapod external fixator (HEF) for the postoperative malalignment correction in tibial diaphyseal fractures treated by monolateral external fixation. MethodsWe carried out a retrospective analysis of 23 trauma patients with tibial diaphyseal fracture treated by the monolateral external fixation at our institution from January 2016 to May 2019. There were 21 males and 2 females with a mean age of 38 years (range 18-60 years). The hexapod external fixator was temporarily applied due to postoperative malalignment within two weeks and who unwilling to undergo a secondary surgical intervention. For patients with postoperative malalignment requiring correction, the HEF components were installed on the original existing half pins of the monolateral external fixator after removing the connecting rod. The standard anteroposterior and lateral X-rays of the injured limb combined with the temporary HEF were conducted to measure the hexapod external fixator parameters. Any residual deformities were corrected by gradual struts adjustment with the aid of computer-based software. When satisfactory alignment was achieved, the HEF was removed, and the monolateral external fixator was sequentially used as the definitive structure. ResultsAll patients acquired functional reduction, which was evaluated by radiographs. The mean correction time was 4 days (range 2 to 8 days). The mean coronal plane translation (1.3±1.0 mm), coronal plane angulation (0.9±0.7°), sagittal plane translation (1.4±1.1 mm), and sagittal plane angulation (0.7±0.7°) after correction were all less than those (7.0±4.9 mm, 4.7±2.3°, 5.6±3.6 mm, 3.2±2.5°) before correction. ConclusionsThe temporary application of the hexapod external fixator is an alternative and feasible method for the postoperative malalignment correction in tibial diaphyseal fractures treated by monolateral external fixation.

Effect of axial dynamization in circular external fixation on bone segment vertical and lateral displacements

Context: The field of deformity correction with external fixation has continued to advance since with the addition of half-pins, even though they can act to stiffen the construct and undermine healing. Dynamization increases axial motion at the fracture site and improves fracture and osteotomy healing in the experimental and clinical studies. No study compares the lateral and vertical displacements of bone segment in dynamized versus nondynamized frames. Aims: The purpose of this study was to compare the segmentary motion in the axial, coronal, and sagittal planes using nondynamized and dynamized circular external fixation frames. Subjects and Methods: Seven frame models were tested including classic Ilizarov three-wire construct and two frame configurations representing the most common modern half-pin and wire combinations. These models were either nondynamized or dynamized with two types of dynamization modules. Each model underwent axial loading up to 50 kg for 11 cycles. Statistical Analysis Used: One-way analysis of variance testing followed by post hoc Tukey's test. Results: The addition of each half pin sequentially decreased axial motion while increased sagittal motion. Dynamization had a limited effect on the sagittal motion but significantly improved axial motion. The sagittal to axial motion ratio increased with half pins in nondynamized frames but decreased equal to or beyond the Ilizarov three-wire fixation frame with dynamization. At the limit of the dynamizers' motion, there was change in the rate of displacement, suggesting that subsequent motion was strictly from the wires and half-pins. Overall, there was minimal coronal motion. Conclusions: While half pins decrease axial micromotion and increase detrimental sagittal motion, dynamization restores.

Expert opinion: Using of antiplatelet agents in surgery with external fixators

Expert opinion: Using of antiplatelet agents in surgery with external fixators

Development of modified Ilizarov hip reconstruction surgery for hip dysfunction treatment in adolescent and young adults

Background/objectiveHip dysfunction in young population caused by developmental dysplasia of the hip, congenital hip deformity or femur head necrosis severely affect the quality of life of young patients, and total hip replacement is the current widely accepted standard therapy for hip function reconstruction in adults, but not for young patients. Alternative safe and effective surgical method for hip function preservation/reconstruction for young patients is lacking. Ilizarov hip reconstruction osteotomy was an alternative method for preserving hip function but the surgical procedures were rather complicated using discomforting ring fixation at the hip region that prevents its wider acceptance and application. Here we reported a modified Ilizarov hip reconstruction surgery for hip dysfunction/deformity correction in adolescent and young adults using femoral shaft osteotomy and simplified unilateral external fixation configuration at the hip region with satisfactory clinical outcomes.MethodsThis is a retrospective study with five male and twelve female patients aged from 10 to 34 years old (mean 20.6 years) including 11 developmental dislocations of the hip and 6 femoral head necrosis. Modified Ilizarov hip reconstruction y surgery was performed using single-arm triangular configuration, threaded half pins on the femur and multiple drill hole guide for osteotomy. The mechanical axis and limb length were corrected spontaneously during the subsequent limb lengthening process in all patients. Preoperative and postoperative gross appearance, radiography of the hip and hip function assessment scores were recorded and compared during the follow-up period.ResultsThe mean follow-up period was 64.3 months (12–87 months). Satisfactory hip appearance, hip and knee functions were achieved in all patients, none resulted in hip replacement surgery at the follow-up period. The mean preoperative and postoperative Harris hip scores were 45.92 ​± ​19.41 and 87.16 ​± ​5.31, respectively (p ​< ​0.01). Pin-track infections occurred in four patients, treated successfully with wound dressing care and oral antibiotics. Restricted range of motion of the knee was observed in eight patients, all gradually overcome by active functional exercises. Osteotomy site fracture of the middle femurs after removing external devices occurred in two patients due to unexpected fall, and complete healing was achieved after plaster fixation. Complications such as fixation device failure, knee dislocation, vessel or nerve impairments did not occur.ConclusionsModified Ilizarov hip reconstruction surgery significantly reduced the surgery time and discomforts to patients, avoided the disturbance of blood supply at the osteotomy sites. This modified method is a useful alternative for correction of hip deformities and reconstruction hip function in adolescent and young adults who are not suitable for conventional pelvis support surgery or hip replacement surgery.Translational potential statementThe modified Ilizarov hip reconstruction surgery provides an alternative for hip replacement surgery with satisfactory clinical outcomes. This procedure is minimally invasive, safe and simple, with few complications compared to conventional pelvis support surgery, and it may be the first choice of surgery for the management of hip dysfunction in adolescent and young adults.

Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction.

AimWe have encountered four cases with Taylor spatial frames (TSF) (Smith & Nephew, Memphis, TN, USA) with breakage at the half-ring junction of the distal ring. This study examines the strain produced on different locations of the distal ring during loading and the effects on the strain of altering the frame construct.Materials and methodsWe mounted two ring TSF constructs on tibia saw bone models. The proximal ring was the same in all constructs and consisted of a 2/3 180 mm ring attached with three wires. Construct 1 is reproducing the configuration of cases where failure was seen. The distal 155 mm ring is attached with three half pins. The half-ring junction is located in the midline. Construct 2 has a different half pin placement and an additional wire on the distal ring. Constructs 3 and 4 have the same half pin configuration to construct 1 but the distal ring is rotated 60° internally and externally, respectively. Strain gauges were attached to different locations and measurements recorded during loading. Statistical analysis was performed.ResultsHighest strain values were recorded at the half-ring junction of constructs 1 and 2 (>600 microstrains (με) in tension). Rotating the ring 60° internally significantly reduces the strain at the half-ring junction (<300 με) whilst external rotation by 60° further reduces the strain (<180 με). Ring strain is higher in areas close to half pin attachments.ConclusionThe highest strain is in the half-ring junction as the half rings are subjected to different loading modes. The thickness of the half-ring is halved and the second moment of area reduced further increasing breakage risk. Placing this junction close to the half pin–frame interface, as dictated by the anatomical safe zone further increases the strain. Rotating the distal ring 60° significantly reduces the strain at the half-ring junction.Clinical significanceRing breakage is a rare but significant complication. This is the first study to address this potential mode of TSF failure. Insights and technical tips from this study can help reduce this.How to cite this articleIliadis AD, Bebja R, Wang K, et al. Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction. Strategies Trauma Limb Reconstr 2020;15(3):146–150.

To evaluate the outcome of Ilizarov ring fixator using hybrid technique in Tibial trauma

Introduction: The management of infected nonunion of the tibia is challenging, particularly with segmental bone loss, multiple draining sinuses, poor soft tissue cover, osteopenia, adjacent joint stiffness, limb deformity, or multidrug-resistant polymicrobial infection. The Ilizarov method permits early rehabilitation and addresses all the problems such as non-union, infection, shortening, soft tissue loss and deformity simultaneously at single stage. The conventional all wire Ilizarov frame has certain disadvantages when done in diaphysis such as Muscle and tendon transfixation which leads to pain and contracture of adjacent joints, neurovascular injury and patient discomfort. Half pins used in hybrid Ilizarov causes minimal transfixation of the surrounding soft tissues and neurovascular injury thus causing less morbidity and increased range of motion. Methods: The present study was a prospective randomized open study in which aim was to evaluate outcome of Ilizarov ring fixator using Hybrid technique in tibial trauma. The study was conducted in 30 skeletally mature patients in Department of Orthopaedics, SGRD University of health sciences, Amritsar from July 2017 to May 2019. The patients were assessed clinically based on history and physical examination. Radiological evaluation using plain antero-posterior and true lateral radiographs of the involved leg was done and evaluated by ASAMI score and complications. Results: Mean age was 37.7 years. Out of 30 cases 24(80%) were male and 6(20%) were female. Right tibia was involved in 24 cases out of 30 cases. 29 cases had history of road side accident and 1 had history of fall from height. The bone results were excellent in 21 cases (70%), good in 6 cases (20%), fair in 2 cases(6.67%) and poor in 1 case(3.33%). Functional results were excellent in 17 cases (56.67%), good in 9 cases (30%) and fair in 4 cases (13.33%). No poor functional result was noted. In present study following complications were noted, limp in 12 cases(40%), ankle stiffness in 7 cases(23.33%), pin site infection in 9 cases(30%), limb oedema in 7 cases(23.33%), knee stiffness in 3 cases(10%), loosening of pins in 2 cases(6.67%), deformity in 2 cases(6.67%) and refracture in 1 case(3.33%). There was no complication of neurovascular injury, malunion, breakage of wires, axial deviation or limb length discrepancy. Conclusion: It is thus concluded in present study that with the use of hybrid Ilizarov fixator, bone results are same, functional results are better, post-operative pain is less, less neurovascular injury, decreased joint stiffness, increased range of movements as compared to conventional all wire Ilizarov fixator. Although studies state that pins increase the stiffness of the frame thus decreasing union rate, we found that union rate in hybrid Ilizarov fixator was same as compared to conventional all wire Ilizarov fixator. Thus we conclude that hybrid Ilizarov fixator is better than conventional Ilizarov fixator in all aspects. Keywords: hybrid ilizarov,half pins,ASAMI Score

Influence of Different Connecting Rod Configurations on the Stability of the Ilizarov/TSF Frame: A Biomechanical Study.

AimThe Ilizarov external fixator (IEF) is frequently used in trauma and elective orthopaedics. Many of its biomechanical variables (ring size, wire diameter, wire number, half pins vs wires, etc.) and their influence on stability and stiffness have been investigated. There is, however, a paucity in the literature regarding the influence of the connecting rod numbers and configurations between the rings on IEF stability. The primary aim of this biomechanical study was to compare the stability between four- and three-rod IEF configurations. Secondarily to assess the difference in stability between symmetrical and asymmetrical spacing of the IEF rods.Materials and methodsA custom jig was designed to facilitate mounting of a basic two-ring IEF in a hydraulic press. Controlled centre and off-centre (thus simulated bending) axial loading was then applied across the frame. The configurations were loaded up to 4,000 N. The frame deformation was plotted and the data were then analysed and interpreted.ResultsNegligible differences were observed between different four- and three-rod configurations as long as the applied force at the loading point (LP) was within the area of support (AOS) created by the rods. The different four-rod constructs were always more stable than the three-rod constructs during bending.ConclusionThere is comparable stiffness between a four-rod and a three-rod IEF construct as long as the LP is within the AOS created by the rods. A four-rod IEF is stiffer than a three-rod IEF in bending.Clinical significanceThis study will possibly change some paradigms regarding the planning and application of IEFs by Orthopaedics Traumatologists and Reconstruction Surgeons.How to cite this articleThiart G, Herbert C, Sivarasu S, et al. Influence of Different Connecting Rod Configurations on the Stability of the Ilizarov/TSF Frame: A Biomechanical Study. Strategies Trauma Limb Reconstr 2020;15(1):23–27.

The effect of different types of half pins on stress transfer parameter during osseointegration

Abstract Failure of an external fixation can occur due to the loosening of the pins that caused by stress shielding of the pins inserted. The stress shielding decreases the density of the bone where the normal density is 1.85 gcm - 3 drops to 0.01 g . c m - 3 . Different types of pins inserted to unite the fractured bone gives different values of stress transfer parameter (STP). By using finite element analysis (FEA), two types of half pins were modelled where both of them are inserted by using pre-drilled insertion technique and a load of 80 N was applied during the simulation to simulate tightening. Therefore, this study aims to determine the effect of different types of half pins on STP during osseointegration, where in this process two types of material will be present which are soft callus and hard callus as the result of the drilling when the pins were inserted. Based on the results, tapered conical half-pin showed a lower value of STP compared to the trocar-tip tapered half pin. This shows that the trocar-tip tapered half-pin is more favourable because a high STP value indicates that the pin has a better load sharing property between the surrounding bone tissue and the pin fixation.

The treatment of nonunion of femoral shaft fractures after intramedullarynaildynamizationwith temporary compression using external fixator followed by relocking of the internal intramedullary nail

Objective To introduce the technique we invented to treat hypertrophic and oligotrophic nonunion of femoral shaft fracture after dynamization of intramedullary nail (IMN) and to report its preliminary results. Methods The data of 2 cases with hypertrophic nonunions of femoral shaft fracture and 1 case with oligotrophic nonunion following IMN dynamization who had been treated by the technique from March 2006 to July 2017 in Beijing Jishuitan hospital were retrospectively studied. There were 2 females and 1 male, aged 50, 66 and 24 years old. 2 parallel half pins were inserted from anterior to posterior at the trochanteric and condylar zones of the femur for antegrade intramedullary nailing patients, and from lateral to medial sides for retrograde intramedullary nailing patient respectively, then the pins were connected with monolateral limb reconstruction fixator. The fracture nonunion site was compressed by the fixator up to 10-15 mm. The holes at the end of intramedullary nail where their screws were removed for dynamization were locked again with 2 locking screws, and then the frame was removed. The patients are allowed to start their rehabilitation and fully bear their body weight 1 day after the operation. Results The three patients were followed up for 25, 22, and 7 months after the surgery, respectively. The X-ray films showed the fracture healed at 7 months in two case, and at 12 months in one. One patient got her nail removed 25 months after the operation, feeling good 37 months after the removal. Conclusion This technique is an option to manage the hypertrophic and oligotrophic fracture nonunion of the femur after dynamization of IMN. It is mini-invasive to the nonunion site, easy to practice and allows early rehabilitation. Key words: Femoral fractures; Fractures, ununited; Fracture fixation, intramedullary; External fixators

Unreamed Intra-Medullary Nail Versus Half Pin External Fixator in Grade III [A & B] Open tibia fractures

BackgroundTibia fracture is the most common long bone fracture. The fractures of tibia are commonly open fractures due to subcutaneous position of the tibia. The choice of technique for stabilization of open tibia fractures includes - External fixation, unreamed intra-medullary nails [URTN], Reamed intra-medullary nails, ORIF with Plating. ObjectivesTo evaluate & compare the results of Unreamed Intra-Medullary Nail Versus Half Pin External Fixator in Grade III [A & B] Open tibia fractures. MethodsThis prospective clinical study [Randomized chit box] was done on 50 patients presenting to our institute within 24 h of injury. Only those who were skeletally mature with open tibia fracture Grade IIIA & IIIB [Gustilo-Anderson] were included in this study. After initial management, radiological assessment was done. Following this adequate wound debridement, skeletal stabilization with either primary URTN or external fixator was done. Inspection and debridement were repeated at 48-h intervals until the wound was considered clean. Results50 cases [25 each group] were compared in terms of - Final Alignment of the Fracture, Presence of Infection/Non-union/Mal-union, Hardware failure, Time to Bone Union, Number of Operative Procedures after index admission. Mean time to full weight bearing was 20.96 weeks in URTN group versus 24.8 weeks in Ex-fix group. 5 in URTN group required further surgery for non-union versus 11 patients in Ex-fix group. There were 6 significant pin track infection. Removal of nail was required in 1 case of deep infection. ConclusionThis study supports the use of the URTN over External fixator in the treatment of severe open tibia fractures.

Half pins stress shielding interaction behavior at implant-bone interface

External fixator (EF) is assembled by pin, ring, rods and locking devices. Pin implantation is used to provide stability for bone healing and osseointegration. Clinical failure of screw implant is reported to occur at the end of screw thread due to screw loosening and screw tightening. It is hypothesized that the same failure mechanism is occurred for pins. This paper presents the finite element (FE) analysis of EF implantation of different half pins on diaphysis of femur bone. Tapered conical half-pin and trocar-tip tapered half- pin were analysed using four types of materials (titanium alloy, stainless steel, magnesium alloy and carbon fiber) to determine the von-Mises stress and stress shielding. It is found that the pins were yielded at the thread of pin near to hard-soft tissue interface, which is agreed with the clinical screw implant fracture. However, magnesium alloy has the lower von- Mises and greater stress shielding (STP) transfer. Thus, trocar-tip tapered magnesium alloy half pin is predicted to be the best material for better stability of bone fixation.