In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans.

Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.

Objectives. The monitoring of fracture healing is a complex process. Typically, successive radiographs are performed and an emerging calcification of the fracture area is evaluated. The aim of this study was to investigate whether different bone healing patterns can be distinguished using a telemetric instrumented femoral internal plate fixator. Materials and Methods. An electronic telemetric system was developed to assess bone healing mechanically. The system consists of a telemetry module which is applied to an internal locking plate fixator, an external reader device, a sensor for measuring externally applied load and a laptop computer with processing software. By correlation between externally applied load and load measured in the implant, the elasticity of the osteosynthesis is calculated. The elasticity decreases with ongoing consolidation of a fracture or nonunion and is an appropriate parameter for the course of bone healing. At our centre, clinical application has been performed in 56 patients suffering nonunion or fracture of the femur. Results. A total of 39 cases of clinical application were reviewed for this study. In total, four different types of healing curves were observed: fast healing; slow healing; plateau followed by healing; and non-healing. Conclusion. The electronically instrumented internal fixator proved to be valuable for the assessment of bone healing in difficult healing situations. Cost-effective manufacturing is possible because the used electronic components are derived from large-scale production. The incorporation of microelectronics into orthopaedic implants will be an important innovation in future clinical care. Cite this article: B. Kienast, B. Kowald, K. Seide, M. Aljudaibi, M. Faschingbauer, C. Juergens, J. Gille. An electronically instrumented internal fixator for the assessment of bone healing. Bone Joint Res 2016;5:191–197. DOI: 10.1302/2046-3758.55.2000611

Traditionally, unstable anterior pelvic ring injuries have been stabilised with an external fixator or by internal fixation. Recently, a new percutaneous technique of placement of bilateral supraacetabular polyaxial screws and subcutaneous connecting bar to assemble an “internal fixator” has been described. We present the surgical technique and early clinical results of using this technique in twenty-five consecutive patients with a rotationally unstable pelvic ring injury and no diastasis of the symphysis pubis treated between April 2010 and December 2013. Additional posterior pelvic stabilisation with percutaneous iliosacral screws was used in 23 of these patients. The anterior device was routinely removed after three months. Radiological evidence of union of the anterior pelvic ring was seen in 24 of 25 patients at a minimum 6 month follow-up. Thirteen patients developed sensory deficits in the lateral femoral cutaneous nerve (five bilateral) and only one fully recovered. The anterior pelvic internal fixator is a reliable, safe and easy percutaneous technique for the treatment of anterior pelvic ring injuries, facilitating the reduction and stabilisation of rotational displacement. However, lateral femoral cutaneous nerve dysfunction is common. The technique is recommended in cases with bilateral or unilateral pubic rami fractures and no diastasis of the symphysis pubis

Introduction: Increasing number of osteoporotic fractures of the femur, especially upper part of the femur creates everyday problem of health services. Treatment of these fractures has been improving markedly during the past 25 years. DHS, gamma nail and some other implants are very useful in everyday surgery. However some of complications still can not be resolved like cut out. Osteoporotic fractures in subtrochanteric area represent even bigger challenging. Diaphyseal fractures are also difficult to be treated. The main problem is quality of osteoporotic bone. Plate with parallel screws doesn’t provide reliable fixation. Intramedulary nails, because of wide channel in distal femur area also don’t provide desirable fixation stability. Material and Method: We analysed results of using of one new device: selfdynamisable internal fixator (SIF) in the series of 389 patients treated because of upper femur fractures. That device has possibilities of spontaneous dynamisation in two axes: along the femoral neck axis and along the diaphyseal axis. Spontaneous dynamisation in the diaphyseal axis is very important if diaphyseal or subrtochanteric fracture or comminuted fracture of the upper femur with subtrochanteric extension treated. For activation of axial dynamisation it not necessary to do any action from outside the body. This feature is activated spontaneously if there is no progress in fracture union within 6–8 weeks. This device provides three-dimensional fixation using clams and rod onto the lateral surface of the femur. The age of patients was from 59 to 87 years. This internal fixator is applied using minimally invasive method – by one or two small incisions. Results: During the treatment it has been confirmed working of self-dynamisation concept. Spontaneous dynamisation in the long axis of the femur has been proven in 21% of patients with subtrochanteric and diaphyseal fractures and it has been proven radiologically that sliding happened between 1–4 mm (average 2.5 mm). Such dynamisation together with 3D configuration of screws resulted in relatively quick fracture healing. Follow up was 19 months (6–60). Altogether 97.6% fractures healed within normal healing time. There were 1 infection, 2 cut out, 1 mechanical complication, 4 delay unions and one non-union. Conclusion: According to results obtained, it can bee concluded that new biological internal fixator is suitable for minimally invasive technique, without opening of fracture site

Despite its clinical significance, metaphyseal fracture healing has received little attention in research and experimental models have been limited. In particular it is not known to what extent the mechanical environment plays a role in metaphyseal fracture healing. Recently, a new murine internal fixation plate has been developed to stabilise fractures in the distal femur under highly standardised conditions. Goal of the current study was to modify this design, in order to be able to evaluate the influence of the fixator bending stiffness on metaphyseal fracture healing in mice.

Adapting the existing single body design, resulting in low flexibility fixation, two new plates were developed with a decreased bending stiffness of approximately 65% and 45% of the original implant (100%). Pilot experiments were performed on 54 animals, whereas the mice were sacrificed and fracture healing assessed radiologically and biomechanically after 14 and 28 days.

MicroCT evaluation confirmed that the osteotomy was created in the trabecular, metaphyseal bone of the distal mouse femora. All bones showed progressive fracture healing over time, with decreased implant stiffness leading to increased periosteal callus formation.

These implants represent an important new research tool to study molecular and genetic aspects of metaphyseal fracture healing in mice under standardized mechanical conditions, in order to improve clinical treatment in challenging situations, such as in osteoporotic bone.

Purposes of study: To design and introduce into clinical practice a more effective fixation method for condylar and supracondylar fractures of the distal femur, which provides secure fixation and permits the use of a minimally invasive surgical technique.

Methods and results: We have designed a novel implant for secure internal fixation of condylar and supracondylar fractures of the distal femur.

This involves a retrograde intramedullary nail with a unique “cruciate” configuration of distal locking bolts which stabilise the fractured condyles in relation to the shaft.

The optimal geometrical configuration of the distal locking bolts has been developed using cadaver studies. Following finalisation of the design, mechanical bench testing of the implant and clinical trials have been completed according to a protocol agreed with the UK Medical Devices Agency.

So far 36 patients have been treated using the implant which has proved to be effective and easy to use. Much less soft tissue dissection is required than when using conventional blade plates or DHS, or even newer “percutaneous” plating methods.

Conclusions: Mechanical testing on simulated specimens of both segmental defects and intercondylar “T” fractures has shown that the retrograde “cruciate” nail compares favourably with fixation with a DHS screw/plate implant.

Following completion of clinical trials, the Medical Devices Agency has granted approval for general use of the implant. It is anticipated that this will greatly facilitate the management of distal femoral fractures particularly those involving intercondylar fracture patterns.

Aim: Prospective study to evaluate the results and the technique of 63 proximal femoral osteotomies in 39 cerebral palsy patients performed with the new Fixclipª biological internal þxator system. Methods: Thirty nine cerebral palsy patients with dislocated or painful subluxing hips, who underwent upper femoral osteotomy from 2 different centres in the last 7 years were included in the study. Results: The average age of patients at operation was 12.7 years (range 3 Ð 60 years). All the patients were followed up until union. Some had removal of the implant. Postoperative splintage was normally used when soft tissue procedures were performed along with femoral osteotomy. Three patients needed revision surgery for readjustment of the device and 2 patients had superþcial infections. All osteotomies healed by 12–16 weeks apart from one. There was no malunions, or avascular necrosis. One patient had a non-union that united after revision surgery. Conclusion: The Fixclips system is modular and easily adjustable. The system lies off the bone with minimal disturbance to the periosteal blood supply. Compared to other implants, Fixclips are biologically and mechanically very effective with low complications and well suited in cerebral palsy patients where rigid þxation can cause extensive loss of bone mass. This is the þrst study reporting the use of ÔFixclipsñ system for upper femoral osteotomy.

Aims. The anterior pelvic internal fixator is increasingly used for the treatment of unstable, or displaced, injuries of the anterior pelvic ring. The evidence for its use, however, is limited. The aim of this paper is to describe the indications for its use, how it is applied and its complications. Patients and Methods. We reviewed the case notes and radiographs of 50 patients treated with an anterior pelvic internal fixator between April 2010 and December 2015 at a major trauma centre in the United Kingdom. The median follow-up time was 38 months (interquartile range 24 to 51). Results. Three patients were excluded from the analysis leaving 47 patients with complete follow-up data. Of the 47 patients, 46 achieved radiological union and one progressed to an asymptomatic nonunion. Of the remaining patients, 45 required supplementary posterior fixation with percutaneous iliosacral screws, 2 of which required sacral plating. The incidence of injury to the lateral femoral cutaneous nerve (LFCN) was 34%. The rate of infection was 2%. There were no other significant complications. Without this treatment, 44 patients (94%) would have needed unilateral or bilateral open reduction and plate fixation extending laterally to the hip joint. Conclusion. The anterior pelvic internal fixator reduces the need for extensive open surgery and is a useful addition to the armamentarium for the treatment of anterior pelvic injuries. It is associated with injury to the LFCN in a third of patients. Cite this article: Bone Joint J 2017;99-B.1232–6

Abstract. Introduction. Intra-articular distal humerus OTA type C fractures are challenging to treat. When osteosynthesis is not feasible one can choose to do a primary arthroplasty of elbow or manage non-operatively. The indications for treatment of this fracture pattern are evolving. Objectives. We present our outcomes and complications when this cohort of patients was managed with either open reduction internal fixator (ORIF), elbow arthroplasty or non-operatively. Methods. Retrospective study to include OTA type C2 and C3 fracture distal humerus of 36 patients over the age of 50 years managed with all the three modalities. Patient's clinical notes and radiographs were reviewed. Results. Between 2016 and 2022, 21 patients underwent ORIF – group 1, 10 patients were treated with arthroplasty – group 2 and 5 were managed conservatively- group 3. The mean age of patients was 62 years in group 1, 70 years in group 2 and 76 years in group 3. The mean range of movement (ROM) arc achieved in the group 1 & 2 was 103 while group 3 was 68. At least follow up was 6 months. 5 patients in group 1 underwent metalwork removal and 2 patients in group 3 under arthroplasty. Conclusion. The outcomes of arthroplasty and ORIF are comparable, but reoperation rates and stiffness were higher in ORIF and conservative group. Surgeon choice and patient factors play important role in decision towards choosing treatment modality. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Locking plates have led to important changes in bone fracture management, allowing flexible biological fracture fixation based on the principle of an internal fixator. The technique of locking plate fixation differs fundamentally from conventional plating and has its indications and limitations. Most of the typical locking plate failure patterns are related to basic technical errors, such as under-sizing of the implant, too short working length, and imperfect application of locking screws. After analysis of the fracture morphology and intrinsic stability following fracture reduction, a meticulous preoperative planning is mandatory under consideration of the principles of the internal fixator technique to avoid technical errors and inaccuracies leading to early implant failure

Since the early nineties clinical experience were gained with locking plates to stabilize long bone fractures. Firstly with a Point Contact Fixator, a device making the step from a conventional plate to an internal fixator, than with pure precontured internal fixators for the periaticular regions or nowadays with plates giving the option for the placement of locking or conventional cortical screws and are so called Locked Compression Plate (LCP). Almost every new development for extraarticular fracture stabilization reflects this development. Despite today’s broad, worldwide acceptance of the fixation technique, someone should be very clear about the benefits and the underlying concept to avoid failures, complications and unnecessary costs. Clear clinical benefits have been proven in complex fractures of the metaphysis and joints, furthermore the fixation of highly osteoporotic and/or periprosthetic fractures became more reliable. Also the technique of minimally invasive plating – the so-called biological plating –, where the fracture zone is only bridged and therefore the fracture often is not exposed any more, was facilitated with the new internal fixators. However, the process should not be overused, particularly in cases of insufficient surgical experience, because the technical demanding minimally invasive procedures can have detrimental effects on the fracture alignment and therefore on the later outcome. Not to forget the extended use of intraoperative x-ray exposure to control the reduction and implant fixation. Applying locking plates, the surgeon should never forget that bone healing requires still prerequisites in respect to stability and, of course, of other biological stimuli. This reflects the ongoing discussion, how a simple long bone fracture, should be optimal stabilized with an internal fixator, the amount of bone/implant fixations contacts and the timing for necessary further operations in present of delayed healing. The opportunity to combine both stabilization options – conventional screw and locking screw placement – within one implant needs a clear understanding of the underlying fixation issues and requires a clear teaching concept to avoid unfavorable combination of the different screws. In this lecture a broad, critical overview about the worldwide impact of locking plates in long bone fracture treatment will be given including proven advantages as well as discussing detected disadvantages using literature evidence and clinical examples

The paper present our results in application of new method for nonunion treatment of the femoral diaphysis. The internal fixator has been applied with 36 patients. Bone graft substitution is used with 11 (30,5%) patients. The method of placement and results of the work according to the modified system of the Karlstrom-Olerud method have been presented. Excellent condition was found with 25 (69,4%) patients, satisfactory with 8 (22,2%) and poor with 3 (8,3%) patients. Average healing time is 57 weeks. The method in which the internal fixator is applied provides complete stability of the nonunion and makes possible spontaneous-biological dinamization of the nonunion. It doesn’t damage the periosteal and medullary bone vascularization which favors healing process

Purpose of the study:. To determine the outcomes of cases converted from an external fixator to an internal fixation device in the management of limb reconstructions and deformity corrections. Method:. A retrospective review of 18 patients, that underwent a conversion procedure to internal fixation following long term external fixation use, was done. This comprised 24 limbs. Inclusion criteria: All cases of long term external fixator use converted to internal fixation over a 5 year period. Average external fixation time, pin site care, conversion timing, surgical device used as well as outcome were documented. Results:. The mean treatment time in an external fixator was 185 days (61–370). The reasons for conversion included patient dissatisfaction, pin tract sepsis and a refracture. The conversion procedures included 8 intramedullary nail fixations and 16 plate and screw fixations. An acute conversion was identified as an internal fixation that was done in the same sitting as external fixator removal. A delayed conversion was any internal stabilisation that was done thereafter. In total, the complication rate associated with conversion to internal fixation following long term external fixation was 25%, mainly due to persistent non-union or sepsis. In the 8 conversions to intramedullary nails, 7 were acute: 4 had good outcomes with sepsis free union being achieved. 3 had poorer outcomes with a non-union and 2 amputations being documented. The single delayed nailing achieved union. In the 16 conversions to plate fixation, 13 achieved union. 10 were acute conversions and 3 were delayed. The remaining 3 that developed complications included 2 acute conversions with septic non-unions and a single delayed conversion which resulted in sepsis. Conclusion:. Conversion of an external fixator to an internal fixator in a non-acute reconstructive setting has a 75% success rate. In the acute conversion group (19 cases), plate and screw fixation had a superior outcome. In the delayed conversion group (5 cases), intramedullary fixation was favoured

In recent years, plate osteosynthesis in metaphyseal and diaphyseal long bone fractures has been increasingly applied in a minimally invasive fashion. Several clinical studies describe a beneficial effect of the smaller additional soft tissue damage, resulting in satisfying fracture and soft tissue healing. However, is the surgical soft tissue damage really evidently smaller and the recovery faster?. A trauma model with severe, circumferential soft tissue damage to the distal right thigh and a distal multifragmentary (AO type C) femur fracture was carried out on 24 male sheep. After five days temporary external fixation, an internal fixator was placed either by a conventional open lateral approach or by minimally invasive technique. To assess the soft tissue damage and its recovery within the first 14 days, local compartment pressure monitoring as well as daily measurements of systemic markers (Creatin Kinase, CK and Lactate Dehydrogenase, LDH) in blood were performed. The local monitoring with a special probe (Neurovent PTO, Raumedic AG, Germany) within the quadriceps muscle allowed the measurement of compartment pressure (CP), as well as temperature. The CK and LDH levels responded to the severe trauma with high peaks within the first 48 hours post trauma. After the internal fixator operations CK levels illustrate a significantly lower increase (p< 0.05) in the minimally invasive group compared to the open approach group in the first two days postoperatively. LDH levels show lower values for the minimally invasive group (p=0.06). The values of CP present an initial increase after the trauma and then higher values (p=0.08) after the open plating operation. For the intracompartmental temperature no statistical differences were found, too (p=0.17). These results, with reduced additional soft tissue damage and faster recovery in the minimally invasive approach group, reflect the clinical experience and expectations. However, while minimally invasive plate osteo-synthesis is certainly a desired option for fracture fixation, good surgical skills are required to insure that the reduced surgical trauma is in line with optimal fracture healing. The influence of the two different approaches on the bone healing per se, as well as the influence on soft tissue functionality, has yet to be demonstrated

Introduction: Proximal tibial fractures continue to be problematic for orthopaedic surgeons. Continued problems in their managment include infection, soft tissue problems, failure of fixation and joint stiffness. Combining the concept of “biological plating” and locked internal fixators, the LISS (Less Invasive Stabilization System) has been developed. Material and methods: The Lis-system is an extramedullary internal fixator that proposes the advantage of indirect reduction and percutaneous, submuscular implant placement. The Lis-system is indicated for fractures of the proximal tibia that involve both the medial and lateral columns. They include AO/OTA Type A2, A3, C1, C2, C3 and type B in selected cases. For the reduction, we put the lower limb in the calcaneal-traction. For intra-articular fractures the prime objective is to achieve anatomic reconstruction of the joint. This study is a prospective evluation of the Lis-System for the treatment of high-energy tibial plateau and proximal tibial fractures treated between October 2002 and Febrary 2004. Twenty-five patient (18 male and 7 female) were treated. The fracture were classified according to the AO classification. The follow-up period between 3 months and 16 months (mean 8.9 months). Results: The fractures treated were 10 intrarticular (AO 41C or 41B) and 15 metaphyseal (AO 41 A); two of these fractures presented with open soft tissue damage. The average age of the patients was 43 years. There were five cases of polytraumatized and four patinetsa with multiple fractures. The mean range of motion was 2 degree (R= 0–13) to 110 degree (R= 80–150). The mean time to full weight-bearing was 16.2 weeks (R= 10–19). There where no non-union. In one case, there was a valgus malunion of about 5 degree, in 2 case a valgus malunion of less of 5 degree and anyone of more of 5 degree. The tecnique of osteosyntesis with the LISS allows a minimally invasive approach, minimizing additional trauma to the soft tissue. There were no cases of varus malunion, of failure or of loss of reduction. One patient developed superficial infection that we treat with antibiotics terapy. No syndrome compartiment were see. Conclusion: In conclusion with the new methods of percutaneus plate osteosyntesis we see decreased soft tissue complication and the time of healing. The Less Invasive Stabilizzation System in our opinion is the goal standard for multisegmentary or comminnuted fractures of the proximal tibia with distal long extensions in patients with politrauma. The early clinical result optain in our experiance indicate that the Less invasive Stabilizzation System combine efficent bone stabilization with the advantage of minimally invasive operative technique

Total hip arthroplasty following pelvic or femoral trauma presents the joint surgeon with challenges not dissimilar to that of revision surgery. Careful preoperative evaluation and planning, and realistic assessment of risks and expectations is necessary. Complex acetabular fractures present the surgeon with a variety of challenges in conversion to total hip replacement (THR). Bone stock is the critical factor in achieving a stable acetabular reconstruction, particularly with regard to the posterior column. In patients who have undergone prior open reduction and internal fixation, routine radiographic examination will often be inconclusive as to the status of healing of fractures due to the presence of metal, and CAT scans will be similarly obfuscated by metal artefact. Therefore, the surgeon must be prepared for the possibility of bone stock deficiency at the time of reconstruction. Subclinical infection following ORIF is possible; all patients should be screened for this possibility with preoperative determination of the ESR and C-reactive protein. If these studies are elevated, aspiration of the hip under x-ray or ultrasound guidance should be considered. At the time of surgery, it is suggested that cultures be obtained prior to the administration of systemic antibiotics, and consideration given to intraoperative frozen section examination of tissue if infection is suspected. Removal of internal fixation devices, debridement, and second stage reconstruction after appropriate antibiotic therapy will be necessary in these cases. Exposure of the hip will be complicated by scar tissue. Particular care is required to avoid sciatic nerve injury during the exposure and hardware removal. Extension of the hip and knee during posterior exposure of the acetabulum and internal fixation devices will aid in retraction and avoidance of neuropraxic sciatic injury. Stainless steel screws and plates should not contact titanium alloy implants in order to avoid the possibility of fretting wear and corrosion of dissimilar metals. Intraarticular exposure of screws or plates mandates removal of the device. In the absence of such exposure, hardware may be left in place. Post-traumatic hip arthritis is frequently associated with avascular necrosis of the femoral head. It is not unusual to see advanced bone loss and collapse of the femoral head, with associated limb shortening. If internal fixation has been performed in the proximal femur, consideration of the appropriate femoral component length is necessary to bypass any stress risers. Calcar replacement implants will be necessary in the face of proximal femoral deficiency. The risk of dislocation following THR in the setting of post-traumatic arthrosis is increased in the presence of soft tissue defects, abductor dysfunction, or neuromuscular deficit. Postoperative bracing may be necessary to assure stability of the reconstruction. The use of a THR orthosis set at 10–15° abduction, 30–60° flexion for 12 weeks following surgery has been successful in preventing dislocation in the setting of abnormal soft tissues

Aim. Radiologic signs such as radiolucent lines around the implant, hardware fracture or displacement and periosteal reaction have been considered suggestive of implant-associated infection. The goal of this study is to assess the correlation of these signs with confirmed internal fixation-associated infection evaluated in a prospective cohort. Method. We evaluated the radiologic appearance of preoperative standard x-ray images in 421 surgeries performed in 380 patients with internal fixation device in place (56.8% male, mean age 53 ± 17 years). This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. Infection was suspected preoperatively in only 23.8% of the surgeries. The most common indications for surgeries in which infection was not suspected were nonunion (84 cases) and symptomatic hardware (57 cases). All removed implants were sent to sonication for biofilm removal and detection. In addition, several peri-implant tissue samples were collected. Radiographs were analyzed in a blinded fashion for signs of radiolucent lines around the implant before removal, hardware fracture or displacement, and soft periosteal reactions suggestive of infection. Diagnosis was established according to the IDSA criteria for PJI. Contingency tables were constructed to determine sensitivity and specificity, and to perform Chi-square tests to compare the presence of infection with radiological signs of infection. Results. Radiologic signs suggestive for infection were uncommon, including radiolucent lines in 48 cases (11.4%); hardware breakage in 542cases (12.4%); hardware displacement in 45 cases (10.7%); periosteal reaction in 30 cases (7.1%). Infection was confirmed in 27.6% of the surgeries, and radiological signs of infection were only marginally more common in this group. Only the presence of radiolucent lines (p = 0.47; OR = 1.86 [95% CI 1.00 – 3.38]) and periosteal reaction (p = 0.15; OR = 2.48 [1.17 – 5.26]) were significantly associated with confirmed infection. Sensitivity of radiolucent lines and periosteal reaction were low (16,4% and 12,1%, respectively), while specificity remained acceptable (90.5%and 94.8%, respectively). Conclusions. Radiologic signs of infection are uncommon, even in the context of a confirmed infection. Radiolucency surrounding the implant and the presence of a soft periosteal reaction were significantly associated with the presence of infection, though sensitivity of the signs remained very low

Aim. Unexpected positive infections are distinct entity in prosthetic revision surgery. The prevalence and characteristics of unexpected positive cultures in internal fixation are however less established. The aim of this study was to describe the prevalence and characteristics of unexpected diagnosis of infection in a prospective cohort of revision surgeries following internal fixation. Method. We reviewed the microbiological results following 356 surgeries that included partial or complete removal of internal fixation, performed in 328 patients (54% male, mean age 53 ± 17 years), in which infection was not initially suspected. This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. The implants most commonly removed were plate and/or screws (281 cases, 78,9%), followed by intramedullary nails (64 cases, 18,0%). The main indications for surgery were nonunion (89 cases, 25%) and symptomatic hardware (70 cases, 19,7%). All removed implants were sonicated, and tissue cultures were obtained depending on the surgeon's criteria. Diagnosis of infection was established by the presence of 2 or more positive tissue cultures (1 with a highly virulent microorganism), or ≥ 50 colony-forming units found in the sonication fluid. Results. Infection was confirmed in 47 cases (13,2%); diagnosis was obtained with tissue cultures in 5 cases (1,4%), sonication in 14 cases (3,9%) and a combination of both sonication and tissue samples in 28 cases (7,9%). In another 24 cases (6,7%), ≥ 50 CFU of low-virulence microorganisms were isolated in the sonication fluid, but no tissue samples were available to confirm the diagnosis. Low-virulent microorganisms such as Propionibacterium acnes (22 cases / 46,8%) or coagulase-negative Staphycoccci (13 cases, 27,7%) were most commonly isolated. Sonication was key for the diagnosis of 61,7% of unexpected-positive surgeries. Nearly half of the patients received a new implant (internal fixation in 40,4%; arthroplasty in 6,4%), but only 34% of the patients were treated with antibiotics on discharge. Conclusions. Unexpected diagnosis of infection occurs in approximately 13,2% of revision surgeries following internal fixation, most commonly due to low-virulent microorganisms. Sonication was key for the diagnosis of the majority of these infections. The clinical relevance of these infections remains unclear, though the insertion of new implants raises concern. We recommend sonication of all internal fixation devices removed, especially if new implants are inserted in the revision surgery

Introduction. Fracture around the knee can lead to posttraumatic osteoarthritis (PTOA) of the knee. Malunion, malalignment, intra-articular osseous defects, retained internal fixation devices, and compromised soft tissues may affect the outcome of total knee replacement (TKR). On average, the posttraumatic patient subsets were 10.4 years younger than those for primary knee OA. Recently, there were several studies reporting the outcome of THA for posttraumatic OA hip. However, no current literature defines the comparative functional outcome between PTOA and primary OA knee. The purpose of our study was to compare the midterm outcomes of patients undergoing TKR following periarticular knee fractures/ligamentous injuries versus primary osteoarthritis (PO) of the knee. Materials and methods. Retrospective chart reviews of patients underwent TKR between 2008 and 2013 were identified. 136 patients underwent open reduction and internal fixation with plate and screws or ligament reconstruction while 716 patients were primary OA. Mean follow up time was comparable in both groups. Demographic data, medical comorbidities, WOMAC, visual analogue scale, and complications were recorded. Results. There were significantly different in age (56.5 vs 63.8 years, p<0.0001), gender (48.5% vs 63.1% of female, p=0.0014), and obese (62.3% vs 76.0%, p=0.025) between PTOA and PO groups, respectively. The PO group had higher comorbidities than PTOA group including anticoagulant usage (51% vs 30.9%, p=0.0002), number of disease ≥ 4 (69.6% vs 45.3%, p<0.0001), ASA class ≥3 (38.8% vs 21.6%, p<0.0001), and Charlson Comorbidity Index (3.6 vs 2.8, p<0.0001). The PTOA group had longer operative time (110.9 vs 100.1 minutes, p<0.0001) than PO group. Preoperatively anatomical axis of the knee was approximately valgus in PTOA but varus alignment in PO group (p<0.0001). However, postoperatively anatomical and mechanical axis was comparable in both groups. Postoperative VAS (1.8 vs 1.2, p=0.002) at 1 year follow up and pain component of WOMAC (77.8 vs 85.7, p=0.013) in PTOA group was worse than PO group, respectively. On the contrary, there was no difference in postoperative complication and readmission rate between groups. Conclusion. Total knee replacement for Post-traumatic OA was associated with poorer functional outcome compared to those for primary osteoarthritis in midterm follow up