Aims. Fracture-Related Infection (FRI) is a severe complication caused by microbial infection of bone. It is imperative to gain more insight into the potentials and limitations of Debridement, Antibiotics and Implant Retention (DAIR) to improve future FRI treatment. The aims of this study were to: 1) determine how time to surgery affects the success rate of DAIR procedures of the lower leg performed within 12 weeks after the initial fracture fixation operation and 2) evaluate whether appropriate systemic antimicrobial therapy affects the success rate of a DAIR procedure. Methods. This multinational retrospective cohort study included patients of at least 18-years of age who developed an FRI of the lower leg within 12 weeks after the initial fracture fixation operation, between January 1st 2015 to July 1st 2020. DAIR success was defined by the absence of recurrence of infection, preservation of the affected limb and retention of implants during the initial treatment. The antimicrobial regimen was considered appropriate if the pathogen(s) was susceptible to the given treatment at the correct dose as per guideline. Logistic regression modelling was used to assess factors that could contribute to the DAIR success rate. Results. A total of 120 patients were included, of whom 70 DAIR patients and 50 non-DAIR patients. Within a median follow-up of 35.5 months, 21.4% of DAIR patients developed a recurrent FRI compared to 12.0% of non-DAIR patients. The DAIR procedure was successful in 45 patients (64.3%). According to the Willenegger and Roth classification, DAIR success was achieved in 66.7% (n=16/24) of patients with an early infection (<2 weeks), 64.4% (n=29/45) of patients with a delayed infection (2–10 weeks) and 0.0% (0/1) of patients with a late infection (>10 weeks). Univariate analysis showed that the duration of infection was not associated with DAIR success in this cohort (p=0.136; OR: 0.977; 95%CI: [0.947–1.007]). However, an appropriate antimicrobial regimen was associated with success of DAIR (p=0.029; OR: 3.231; 95%CI: [1.138–9.506]). Conclusions. Although the results should be interpreted with caution, an increased duration of infection was not associated with a decreased success rate of a DAIR procedure in patients with FRI of the lower leg. The results of this study highlight the multifactorial contribution to the success of a DAIR procedure and emphasize the importance of adequate antimicrobial treatment. Therefore, time to surgery should not be the only key-factor when considering a DAIR procedure to treat FRI

Aim. Soft tissue defects of the lower leg can be closed - following the reconstructive ladder - with a pediculated fasciocutaneous suralis flap, but a free flap is gold standard in most of the cases. Aim of the study was to evaluate complications, risk factors for failure and the reasonableness of this procedure. Method. 91 patients (92 flaps, 70 males, 21 females) with a mean Age of 55 years (16 to 87) were included in the study. The patients had mean four surgical procedures before the flap, the follow-up was mean 407 days. 70 patients were classified ASA I or ASA II. Results. There were many complications, mostly wound healing Problems or hematoma. Only 40% of the patients received no Revision surgery, 71% of the flaps reached healing with Maximum two revisions (22% with one, 9% with two revisions, respectively). Necrectomy and new meshgraft were main reasons for Revision. Long term complications were swelling or disturbance of sensitivity. We lost seven flaps, eight free flaps were necessary. Three amputations were performed, but only one because of the lost flap. Conclusions. All patients with lost flaps showed relevant comorbidities. 71% of the flaps healed with Maximum two revisions and the overall flap loss rate was 6%. The Advantages of this flap are short surgery time without the need of a microvascular anastomosis and a relatively simple surgical technique. The flap loss rate of 6% seems to be acceptable and, however, the flap is a good Option and an important step of the reconstructive ladder for soft tissue defect closure of the lower leg

Aim. Since surgical site infections (SSIs) remain among the most common complications of orthopedic (trauma) surgery, there has been unwavering attention for potential predictors of a SSI. Specifically in surgical fields with a high complication rate, such as foot/ankle surgery, risk factor identification is of great importance. Recently, some studies have suggested environmental factors such as season to be of influence on the number of SSI. Specifically patients operated on in the summer are reported to have a higher incidence of SSIs, compared to other seasons. The aim of this study is to identify if “seasonality” is a significant predictor for SSI in a cohort of (trauma) surgical foot and ankle procedures. Method. This retrospective cohort study included all patients undergoing trauma related surgery (fracture fixation, arthrodesis, implant removal and tendon repair) of the lower leg, ankle and foot. Procedures were performed at a single Level 1 Trauma Center in the Netherlands between September 2015 until February 2019. Potential risk factors/ confounders for SSI were identified using univariate analysis (Chi-Square/Mann-Whitney U). Procedures were divided in two groups: 1) performed in summer (June, July or August), 2) not performed in summer (September-May). The number of SSIs was compared between the 2 groups, correcting for confounders, using multivariate regression. Results. A total of 605 procedures were included, largely fracture fixation (371, 61.2%). Patients were on average 46 y/o and the majority was male (369, 60.9%). The total number of SSIs was 34 (5.6%). Age, American Society of Anesthesiologists (ASA) classification (1–2 or 3–4) and open fractures were identified as possible predicting factors of SSI. No difference in SSIs was found between summer and other seasons, neither in univariate analysis (4 (3.2%) vs 30 (6.3%), p=0.271), nor when corrected for confounders. Moreover, in multivariate analysis only an ASA of >2 and an open fracture remained as independent predictors of SSI. Conclusions. No seasonality could be identified in the rate of SSI after trauma surgery of the lower leg, ankle and foot in this cohort. A possible explanation for this lack of effect could be the temperate oceanic climate of the Netherlands. Larger temperature and precipitation differences may also influence the incidence of SSIs. However, previous studies suggesting seasonality in SSIs might also be purely based on coincidence, especially when uncorrected for confounders

Introduction. Fully implantable distraction nails are frequently used for lengthening of the lower leg. What are the indications for humerus lengthening and which results can be expected?. Materials and Methods. The humerus as the best healing bone in the human body is suitable for lengthening with a nail as well but the indications are rare in comparison with the lower legs. Especially when driving a car or when working on a tablet length discrepancy of the arms of more than 4–5cm may cause severe hardening of the cervical muscles and induce chronical pain in the upper spine. Results. A distraction nail (FITBONE) was used in 5 cases for humerus lengthening. The nail was inserted in all cases from proximal. The mean age of the patients was 34 years. The mean lengthening amount was 58mm (55–100). In one case the system was exchanged to reach the desired length. There was no infection, no radial nerve irritation and no chronical shoulder pain. The system was removed in 4 cases in an average of 15 months the other nail will be removed soon as well. Conclusions. The preliminary results of our 5 cases demonstrate, that the FITBONE device is advantageous for lengthening the humerus, if the initial length is sufficient for implantation. In comparison with the use of external fixators the functional outcome, the comfort of treatment and the cosmetic result is amazing

Aim. Fracture-related infection (FRI) is a severe post-traumatic complication which can be accompanied with a soft-tissue defect or an avital soft-tissue envelope. In these cases, a thoroughly planned orthoplastic approach is imperative since a vital soft-tissue envelope is mandatory to achieve fracture union and infection eradication. The aim of our study was to analyse plastic surgical aspects in the management of FRIs, including the type and outcome of soft-tissue reconstruction (STR), and to investigate the long-term outcome of FRI after STR. Method. Patients with a lower leg FRI requiring STR that were treated from 2010 to 2018 at our center were included in this retrospective analysis. STR involved the use of local, pedicled and free flaps. The primary outcome was the success rate of STR, and the secondary outcome was long-term fracture consolidation and cure of infection. Results. Overall, 145 patients with lower leg FRI were identified, of whom 58 (40%) received STR. Muscle flaps were applied in 38, fascio-cutaneous flaps in 19 and a composite osteo-cutaneous flap in one case. All patients underwent successful STR (primary STR in 51/58 patients, 7/58 patients needed secondary STR). A high Charlson Comorbidity Index Score was a significant risk factor for flap failure (p=0.011). Patients with free-flap STR developed significantly more severe complications and needed more surgical interventions (Clavien-Dindo ≥IIIa; p=0.001). Out of the 43 patients that completed long-term follow-up (mean 24 months), fracture consolidation was achieved in 32 and infection eradication in 31. Polymicrobial infection was a significant risk factor for fracture non-union (p=0.002). American Society of Anesthesiologists (ASA) classification of 3 or higher (p=0.040) was a risk factor for persistence or recurrence of infection. Conclusions. In our population, 58/145 patients with FRI required STR. STR was successful in all patients eventually, in 7/58 patients secondary STR was necessary. Therefore, STR should be sought even if primary STR fails. Despite successful STR, the long-term composite outcome showed a high rate of failed fracture consolidation and failed eradication of infection, which was independent of primary STR failure

INTRODUCTION. There is a growing interest in surgical variables that are controlled by the orthopaedic surgeon, including lower leg alignment and soft tissue balancing. Since more tight control over these factors is associated with improved outcomes of total knee arthroplasty (TKA), several computer navigation systems have been developed. Many meta-analyses showed that mechanical axis accuracy and component positioning are improved using computer navigation and one may therefore expect better outcomes with computer navigation but studies showing this are lacking. Therefore, a systematic review with meta-analysis was performed on studies comparing functional outcomes of computer-navigated and conventional TKA. Goals of this study were to (I) assess outcomes of computer-navigated versus conventional TKA and (II) to stratify these results by the surgical variables the systems aim to control. METHODS. A systematic search in PubMed, Embase and Cochrane Library was performed for comparative studies reporting functional outcomes of computer-navigated versus conventional TKA. Knee Society Scores (KSS) Total were most often reported and studies reporting this outcome score were included. Outcomes of computer-navigated and conventional TKA were compared (I) in all studies and (II) stratified by navigation systems that only controlled for lower leg alignment or systems that controlled for lower leg alignment and soft tissue balancing. Level of evidence was determined using the adjusted Oxford Centre for Evidence-Based Medicine tool and methodological quality was assessed using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) tool. Outcomes were reported in mean difference (MD) with 95% confidence intervals [Lower Bound 95%, Upper Bound 95%]. RESULTS. Twenty-eight studies reported KSS Total outcomes in 3,504 patients undergoing computer-navigated or conventional TKA. Fifteen studies were evidence level I, five studies level II and eight studies level III. Study quality varied between low and high with most studies having high methodological quality. Patients reported better outcomes following computer navigated TKA than conventional TKA (MD 2.86 [0.96, 4.76], p=0.003), which was both seen at short-term follow-up of six months and one year (MD 5.20 [3.41, 7.00] and MD 8.46 [0.65, 16.28], respectively) and at mid-term follow-up (≥4 years) (MD 2.65 [0.96, 4.76]) (Figure 1). In studies that used computer navigation for controlling lower leg alignment, no difference in functional outcomes was seen between computer-navigated and conventional TKA (MD 0.66 [−2.06, 3.38], p=0.63, Figure 2). However, in studies that used computer navigation for controlling lower leg alignment and soft tissue balancing, patients reported superior functional outcomes following computer-navigate over conventional TKA (MD 4.84 [1.61, 8.07], p=0.003, Figure 3). CONCLUSION. This is the first meta-analysis showing superior functional outcomes following computer-navigated over conventional TKA. Stratifying results by variables the systems control, superiority in functional outcomes following computer-navigated over conventional TKA were only seen in systems that controlled soft tissue balancing. This suggests that soft tissue balancing plays an important role in short-term outcomes of TKA. Manually controlling all these surgical variables can be difficult for the orthopaedic surgeon and findings in this study suggest that computer navigation may help managing these multiple variables and improve outcomes. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Aim. The incidence of deep infections after internal fixation of ankle and lower leg fractures is estimated 1 to 2%. Hindfoot arthrodesis by retrograde intramedullary nailing (IMN) is a potential alternative to external fixation for post-infectious ankle destruction. The aim of this study was to evaluate the clinical results, complications and effects of soft tissue management with this treatment modality. Method. This is a single-center retrospective review of routine hospital data from 21 patients (15 men, 6 women, median age 65 [range, 21 to 87] years) undergoing IMN arthrodesis of the hindfoot for post-traumatic infections between January 1st, 2012 and March 15, 2018. We observed four bimalleolar, eight trimalleolar, three pilon fractures, and six distal lower leg fractures. Six and three patients had sustained second- and third degree open fractures, respectively. Early- and late-onset surgical infections were observed in 8 and 13 cases. Four participants had diabetes mellitus, two arterial occlusive disease, and four had both. Six patients were smokers. Results. Intraoperative cultures before implanting the nail revealed staphylococcus aureus in 12, staphylococcus epidermidis in five, and enterococcus faecalis in eight cases. After a median follow-up of 21 months, infection was considered cured in 19 / 21 subjects (90%, 95% confidence interval 70 – 99%). Soft tissue comminution required coverage with a suralis flap in five patients, and with a latissimus dorsi flap in another three. Mesh graft was necessary in 8 / 21 reconstructions. Conclusions. Tibiotalocalcaneal fusion by IMN is an effective salvage procedure for post-traumatic ankle infections. Arthrodesis and definitive wound closure or plastic flap coverage can be performed as single-stage surgery. By resecting the prominent distal fibula, lateral soft tissue defects can be managed more easily. The small sample size prohibited a more detailed analysis of exposure variables, but 8 / 13 patients in this cohort had at least one known risk factor for infection and prolonged healing

CASN is generally good at bone morphing and sizing, assisting with component orientation, gap balancing and providing reasonably accurate alignments of limb and components alike. However, such routine navigation technique fails to use the full potential of the registered information. Current technique provides reasonable static stability information in the coronal plane, but with axial and sagittal planes less well considered. A more dynamic approach seems to be necessary to define ‘potential envelopes of motion’, seeming to be the best possible way in which CASN will finally show fundamental improvements over ‘conventional’ technique. Enhanced dynamic assessment using an upgraded CASN system (Brainlab) is now capable of improved ROM analysis and contact point observations. This consists of storing dynamic information including a) epicondylar axis motion, b) valgus and varus alignments, c) antero-posterior shifts, as well as d) flexion and extension gaps. Tracking values for both tibiofemoral and patellofemoral motion can also be obtained after performing registration of the prosthetic trochlea. Observations can be made using a set of standardised dynamic tests. Firstly, the lower leg can be placed in neutral alignment and the knee put through a flexion-extension cycle. Secondly the test can be repeated but with the lower leg being placed into varus and internal rotation. The third test can be performed with the lower leg in valgus and external rotation. Also a new passive technique of ‘Drop and Push Testing’ into a) flexion and b) extension is giving new information which may prove useful a) in terms of over-stuffing of the extensor mechanism and tightness of flexion gap and b) provision of hyperextension to assist gait. Upgraded software prompts can improve workflows to facilitate optimisation of joint dynamics. Twenty total knee arthroplasties have been studied using these techniques with particular reference to the patterns of instability found. Marked intra-operative variation in the stability characteristics of the trial implanted joints has been quantified before corrections have been made and final assessments performed. These corrections have also been analysed in terms of change in antero-posterior translations, rotations and contact points. Edge loading and excessive paradoxical motions have been identified and corrective measures carried out, thereby improving PCL tensioning. Component rotations, tibial slope angles, insert thicknesses and femoral sizing have had to be adjusted to optimise range of motion and stability characteristics. Certain cases have been identified where use of more congruent or even stabilised components was considered necessary. Patellar tracking has also been observed during such dynamic tests and appropriate adjustments made to components and soft tissue balancing. In summary, this study has enabled intra-operative observation, classification and quantification of patterns of instability in 6 degrees of freedom using simple stress tests followed by appropriate adjustments

Introduction. In orthopaedics one of the most common complications is infection. The occurrence of a postoperative infection significantly increases the failure rate; both in the case of prosthetic and trauma surgery. Some patients despite a meticulous antiseptic procedures, a close monitoring of controls peri- and post-operative undergo the development of infection of the fixation devices with the risk of developing osteomyelitis. This risk is highly increased in the distal leg because of the known problems with blood supply and poor muscle coverage. The functionality of the affected segment is impaired, quoad fuctionem, with increased risk of amputation and sometimes with poor prognosis, quoad vitam. The therapeutic strategy proposed by our group is to treat an osteomyelitic site as a pseudo-tumor with a megaimplant following a ladder strategy driven by the NUSS classification. This work shows our experience with a developing system by Waldemar-LINK highlighting critical issues and preliminary results. Objectives. The purpose of this study is to evaluate retrospectively the early outcome after the implantation of this megaprosthesis of the lower leg in infected post-traumatic bone defects and septic peri-device bone loss. We registered all the complications and infection recurrence. Methods. Between January 2013 today we have developed this system following the chamber induction technique (C.I.T.). We perform a 2 steps procedure: 1° step: resection, debridement, devices removal and bi-antibiotic spacer implantation; 2° step: spacer removal and megaprosthesis implantation. Results. Our first 10 patients with lower leg septic critical size bone defect were post-traumatic, 3 have ended the C.I.T. procedure with good clinical result and return to function. Conclusions. The background experience in orthopaedic oncology, has allowed to develop megaimplants to break the vicious cycle of osteomyelitis and restore an optimal performance of the affected segment. We can perform a one step procedure only when all the infected segment is entirely removed, in other partial resections is better to follow a two steps procedure. In the development of this project will be possible to connect to a Megasystem C; this system will then be able to replace from the hip to the foot in the most complex cases. We also concluded that this type of complex surgery must be performed in specialized centers where knowledge and technologies are present

Purpose. Implant positioning is one of the critical factors influencing the postoperative outcome in total hip arthroplasty (THA). Conventional (manual) intraoperative stem adjustment may result in variability and inaccuracy of stem antetorsion (AT). Since March 2013, we have measured stem antetorsion with CT free Navigation system (OrthoPilot Navigation System THA Pro Ver4.2, B/Braun Aesculap Germany: Navi). We have developed a simple instrument, the Gravity-guide (G-guide), for intraoperative assessment and adjustment of stem AT. We evaluated the accuracy and effectiveness of G-guide and navigation software as referenced to postoperative CT evaluation with 3D template system (Zed hip, LEXI, Japan). Method. Between March 2013 and December 2014, 50 patients underwent primary THA were evaluated. Surgeries were performed with routine techniques with a modified Hardinge approach with the patient at a lateral decubitus position in all cases. The G-guide consists of two parts: one attached to the lower leg and the other attached to the handle of the rasp. During surgery, AT value was determined with navigation at the time of final rasping of the femur. Additionally, the G-guide was utilised at the time of final rasp insertion. In intraoperative AT assessment using this instrument, a correction was required considering the discrepancy between the perpendicular to the posterior condylar axis and the longitudinal axis of the lower leg. The angle of discrepancy between posterior condylar line and femoral trans-epicondyler axis needs to be taken into consideration. Therefore, correction by the angle between the trans-epicondylar and posterior condylar lines (correction angle) was required for each patient when the intraoperative AT as measured by the G-guide. Therefore, the correction angle should be added to the AT value obtained from the G-guide for comparison with postoperative value measured with Zed Hip. Result. The discrepancy between the intraoperative G-guide with correction angle and postoperative Zed Hip measurements was 4.7° ± 3.9°. The discrepancy between Navi AT and postoperative Zed HIP measurements was 5.9° ± 4.1°. A discrepancy was 10° or more were 7 cases in Navi and 4 cases in G-guide. Conclusion. Navi and G-guide measured intraoperative stem antetorsion was comparable utility

INTRODUCTION. Medial and lateral unicompartmental knee arthroplasty (UKA) are both reliable treatment options for isolated osteoarthritis. Postoperative lower leg alignment is known to play an important role on short-term functional outcomes, which is an important argument for the use of robotic-assisted surgery. Since several anatomical and kinematic differences exist between both compartments, it seems inaccurate to aim for similar postoperative lower leg alignment in medial and lateral UKA. Purpose of this study was (I) to compare outcomes between both procedures and (II) to assess the role of preoperative and postoperative alignment on short-term outcomes in both procedures. METHODS. Patients who underwent robotic-assisted medial or lateral UKA were included if they completed functional outcomes questionnaires preoperatively and postoperatively (Western Ontario and McMaster Universities Arthritis score) and completed an artificial joint awareness questionnaire (Forgotten Joint Score) postoperatively (not used preoperatively). A total of 143 medial UKA and 36 lateral UKA patients were included and mean follow-up was 2.4-years (range: 2.0 – 5.0 year). Postoperative alignment was measured using hip-knee-ankle radiographs with a standardized method. Alignment was categorized in medial and lateral UKA as undercorrection (3° to 7° varus or valgus, respectively), neutral (−1° to 3° varus or valgus, respectively), or overcorrection (3° to 7° valgus or varus, respectively). Outcomes were compared using independent t-tests and Pearson correlation analysis was performed to assess a correlation between alignment and outcomes. RESULTS. No preoperative differences in functional outcomes were seen between medial UKA (54.9 ±14.9) and lateral UKA (50.3 ±13.4, p=0.304). Postoperatively, equivalent outcomes were noted between medial and lateral UKA in overall function (89.8 ±11.7 vs. 90.2 ±12.4, respectively, p=0.855) and joint awareness (71.2 ±24.5 vs. 70.9 ±28.2, respectively, p=0.956). Correlation analysis did not show a correlation between preoperative alignment and both functional outcomes and joint awareness for both procedures (all p > 0.4, Figure 1). More undercorrection was correlated with better functional outcomes (−0.355, p = 0.039) and less joint awareness (−0.540, p=0.005) in lateral UKA (Figure 2). In medial UKA, no correlation was noted between postoperative alignment and both functional outcomes (p=0.104) and joint awareness (p=0.069, Figure 2). With neutral postoperative alignment, less joint awareness was noted following medial UKA than lateral UKA (72.6 ±22.6 vs. 55.3 ±28.5, p=0.024). With undercorrection, however, significantly less joint awareness (85.3 ±19.5 vs. 68.2 ±26.8, p=0.024) and better functional outcomes (96.0 ±5.4 vs. 88.5 ±11.6,p=0.001) were noted following lateral UKA than medial UKA (Figure 3). CONCLUSION. At short-term follow-up, equivalent outcomes were noted between medial and lateral UKA but the optimal postoperative alignment differed between both procedures. Undercorrection (3° to 7° valgus) resulted in most optimal outcomes in lateral UKA, while this was with neutral alignment (−1° to 3° varus) in medial UKA. This study showed that postoperative alignment plays a role on short-term outcomes of UKA and suggests that precise control of postoperative alignment should be pursued, which is possible with computer navigation or robotic-assisted surgery in UKA. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Anatomical referencing, component positioning, limb alignments and correction of mechanical axes are essential first steps in successful computer assisted navigation. However, apart from basic gap balancing and quantification of ranges of motion, routine navigation technique usually fails to use the full potential of the registered information. Enhanced dynamic assessment using an upgraded navigation system (Brainlab V. 2.2) is now capable of producing enhanced ‘range of motion’ analysis, ‘tracking curves’ and ‘contact point observations’. ‘Range of motion analysis’ was performed simultaneously for both tibio-femoral and patella-femoral joints. Other dynamic information including epicondylar axis motion, valgus and varus alignments, antero-posterior tibio-femoral shifts, as well as flexion and extension gaps were simultaneously stored as a series of ‘tracking curves’ throughout a full range of motion. Simultaneous tracking values for both tibiofemoral and patellofemoral motion was also obtained after performing registration of the prosthetic trochlea. However, there seems to be little point in carrying out such observations without fully assessing joint stability by applying controlled force to the prosthetic joint. Therefore, in order to fully assess ‘potential envelopes of motion’, observations have been made using a set of standardised simple dynamic tests during insertion and after final positioning of trial components. Also, such tests have been carried out before and after any necessary ligament balancing. Firstly, the lower leg was placed in neutral alignment and the knee put through a flexion-extension cycle. Secondly the test was repeated but with the lower leg being placed into varus and internal rotation. The third test was performed with the lower leg in valgus and external rotation. Force applied was up to the point where resistance occurred without any gross elastic deformation of capsule or ligament in a manner typical of any surgeon assessing the stability of the construct. Also a passive technique of using gravity to ‘Drop-Test’ the limb into flexion and extension gave useful information regarding potential problems such as blocks to extension, over-stuffing of the extensor mechanism and tightness of the flexion gap. All the definitive tests were performed after temporary medial capsular closure. Ten total knee arthroplasties have been studied using this technique with particular reference to the patterns of instability found before, during and after adjustments to component positioning and ligament balancing. Marked intra-operative variation in the stability characteristics of the trial implanted joints has been quantified before correction. These corrections have been analysed in terms of change in translations, rotations and contact points induced by any such adjustments to components and ligament. Certain major typical patterns of instability have begun to be identified including excessive rotational and translational movements. Instability to valgus and external rotational stress was found in two cases and to varus and internal rotational stress in one case before correction. In particular, surprising amounts of edge loading in mid-flexion under stress testing has been identified and corrective measures carried out. Reductions in paradoxical tibio-femoral antero-posterior motion were also observed. Global instability and conversely tightness were also observed in early stages of surgery. Adjustments to component sizes, rotations, tibial slope angles and insert thickness were found to be necessary to optimise range of motion and stability characterisitics on an almost case-by-case basis. Two cases were identified where use of more congruent or stabilised components was necessary. Observation of quite marked loss of contact between tibia and femur was seen on the lateral side of the knee in deep flexion in several cases. Patellar tracking was also being observed during such dynamic tests and in two cases staged partial lateral retinacular releases were carried out to centre patellar tracking on the prosthetic trochlea. Although numbers in this case series are small, it has been possible to begin to observe, classify and quantify patterns of instability intra-operatively using simple stress tests. Such enhanced intra-operative information may in future make it possible to create algorithms for logical and precise adjustments to ligaments and components in order to optimise range of motion, contact areas and stability in TKR

Summary. The mathematical model has proven to be highly accurate in measuring leg length before and after surgery to determine how leg length effects hip joint mechanics. Introduction. Leg length discrepancy (LLD) has been proven to be one of the most concerning problems associated with total hip arthroplasty (THA). Long-term follow-up studies have documented the presence of LLD having direct correlation with patient dissatisfaction, dislocation, back pain, and early complications. Several researchers sought to minimize limb length discrepancy based on pre-operative radiological templating or intra-operative measurements. While often being a common occurrence in clinical practice to compensate for LLD intra-operatively, the center of rotation of the hip joint has often changes unintentionally due to excessive reaming. Therefore, the clinical importance of LLD is still difficult to solve and remains a concern for clinicians. Objective. The objective of this study is two-fold: (1) use a validated forward-solution hip model to theoretically analyze the effects of LLD, gaining better understanding of mechanisms leading to early complication of THA and poor patient satisfaction and (2) to investigate the effect of the altered center of rotation of the hip joint regardless LLD compensation. Methods. The theoretical mathematical model used in this study has been previously validated using fluoroscopic results from existing implant designs and telemetric devices. The model can be used to theoretically investigate various surgical alignments, approaches, and procedures. In this study, we analyzed LLD and the effects of the altered center of rotation regardless of LLD compensation surgeons made. The simulations were conducted in both swing and stance phase of gait. Results. During swing phase, leg shortening lead to loosening of the hip capsular ligaments and subsequently, variable kinematic patterns. The momentum of the lower leg increased to levels where the ligaments could not properly constrain the hip leading to the femoral head sliding from within the acetabular cup (Figure 1). This piston motion led to decreased contact area and increased contact stress within the cup. Leg lengthening did not yield femoral head sliding but increased joint tension and contact stress. A tight hip may be an influential factor leading to back pain and poor patient satisfaction. During stance phase, leg shortening caused femoral head sliding leading to decreased contact area and an increase in contact stress. Leg lengthening caused an increase in capsular ligaments tension leading to higher stress in the hip joint (Figure 2). Interestingly, when the acetabular cup was superiorized and the surgeon compensated for LLD, thus matching the pre-operative leg length by increasing the neck length of the femoral implant, the contact forces and stresses were marginally increased at heel strike (Figure 3). Conclusion and Discussion. Altering the leg length during surgery can lead to higher contact forces and contact stresses due to tightening the hip joint or increasing likelihood of hip joint separation. Leg shortening often lead to higher stress within the joint. Further assessment must be conducted to develop tools that surgeons can use to ensure post-operative leg length is similar to the pre-operative condition. For any figures or tables, please contact authors directly

During the preoperative examination, surgeons determine whether a patient, with a degenerative hip, is a candidate for total hip arthroplasty (THA). Although research studies have been conducted to investigate in vivo kinematics of degenerative hips using fluoroscopy, surgeons do not have assessment tools they can use in their practice to further understand patient assessment. Ideally, if a surgeon could have a theoretical tool that efficiently allows for predictive post-operative assessment after virtual surgery and implantation, they would have a better understanding of joint conditions before surgery. The objectives of this study were (1) to use a validated forward solution hip model to theoretically predict the in vivo kinematics of degenerative hip joints, gaining a better understanding joint conditions leading to THA and (2) compare the predicted kinematic patterns with those derived using fluoroscopy for each subject. A theoretical model, previously evaluated using THA kinematics and telemetry, was used for this study, incorporating numerous muscles and ligaments, including the quadriceps, hamstring, gluteus, iliopsoas, tensor fasciae latae, an adductor muscle groups, and hip capsular ligaments. Ten subjects having a pre-operative degenerative hip were asked to perform gait while under surveillance using a mobile fluoroscopy unit. The hip joint kinematics for ten subjects were initially assessed using in vivo fluoroscopy, and then compared to the predicted kinematics determined using the model. Further evaluations were then conducted varying implanted component position to assess variability. The fluoroscopic evaluation revealed that 33% of the degenerative hips experienced abnormal hip kinematics known as “hip separation” where the femoral head slides within the acetabulum, resulting in a decrease in contact area. Interestingly, the mathematical model produced similar kinematic profiles, where the femoral head was sliding within the acetabulum (Figure 1). During swing phase, it was determined that this femoral head sliding (FHS) is caused by hip capsular laxity resulting in reducing joint tension. At the point of maximum velocity of the foot, the momentum of the lower leg becomes too great for capsule to properly constrain the hip, leading to the femoral component pistoning outwards. During stance phase, kinematics of degenerative hips were similar to kinematics of a THA subject with mal-positioning of the acetabular cup. Further evaluation revealed that if the cup was placed at a position other than its native, anatomical center, abnormal forces and torques acting within the joint lead to the femoral component sliding within the acetabular cup. It was hypothesized that in degenerative hips, similar to THA, the altered center of rotation is a leading influence of FHS (Figure 2). The theoretical model has now been validated for subjects having a THA and degenerative subjects. The model has successfully derived kinematic patterns similar to subjects evaluated using fluoroscopy. The results in this study revealed that altering the native joint center is the most influential factor leading to FHS, or more commonly known as hip separation. A new module for the mathematical model is being implemented to simulate virtual surgery so that the surgery can pre- operatively plan and then simulate post-operative results

Aims

As an alternative to external fixators, intramedullary lengthening nails (ILNs) can be employed for distraction osteogenesis. While previous studies have demonstrated that typical complications of external devices, such as soft-tissue tethering, and pin site infection can be avoided with ILNs, there is a lack of studies that exclusively investigated tibial distraction osteogenesis with motorized ILNs inserted via an antegrade approach.

Aims

Chronic osteomyelitis (COM) of the lower limb in adults can be surgically managed by either limb reconstruction or amputation. This scoping review aims to map the outcomes used in studies surgically managing COM in order to aid future development of a core outcome set.

Background. In vivo fluoroscopic studies have proven that femoral head sliding and separation from within the acetabular cup during gait frequently occur for subjects implanted with a total hip arthroplasty. It is hypothesized that these atypical kinematic patterns are due to component malalignments that yield uncharacteristically higher forces on the hip joint that are not present in the native hip. This in vivo joint instability can lead to edge loading, increased stresses, and premature wear on the acetabular component. Objective. The objective of this study was to use forward solution mathematical modeling to theoretically analyze the causes and effects of hip joint instability and edge loading during both swing and stance phase of gait. Methods. The model used for this study simulates the quadriceps muscles, hamstring muscles, gluteus muscles, iliopsoas group, tensor fasciae latae, and an adductor muscle group. Other soft tissues include the patellar ligament and the ischiofemoral, iliofemoral, and pubofemoral hip capsular ligaments. The model was previously validated using telemetric implants and fluoroscopic results from existing implant designs. The model was used to simulate theoretical surgeries where various surgical alignments were implemented and to determine the hip joint stability. Parameters of interest in this study are joint instability and femoral head sliding within the acetabular cup, along with contact area, contact forces, contact stresses, and ligament tension. Results. During swing phase, it was determined that femoral head pistoning is caused by hip capsule laxity resulting from improperly positioned components and reduced joint tension. At the point of maximum velocity of the foot (approximately halfway through), the momentum of the lower leg becomes too great for a lax capsule to properly constrain the hip, leading to the femoral component pistoning outwards. This pistoning motion, leading to separation, is coupled with a decrease in contact area and an impulse-like spike in contact stress (Figure 1). During stance phase, it was determined that femoral head sliding within the acetabular cup is caused by the proprioceptive notion that the human hip wants to rotate about its native, anatomical center. Thus, component shifting yields abnormal forces and torques on the joint, leading to the femoral component sliding within the cup. This phenomenon of sliding yields acetabular edge-loading on the supero-lateral aspect of the cup (Figure 2). It is also clear that joint sliding yields a decreased contact area, in this case over half of the stable contact area, corresponding to a predicted increase in contact stress, in this case over double (Figure 2). Discussion. From our current analysis, the causes and effects of hip joint instability are clearly demonstrated. The increased stress that accompanies the pistoning/impulse loading scenarios during swing phase and the supero-lateral edge-loading scenarios during stance phase provide clear explanations for premature component wear on the cup, and thus the importance of proper alignment of the THA components is essential for a maximum THA lifetime. For any figures or tables, please contact authors directly

Introduction. In revision TKA, the management of bone loss depends on location, type, and extent of bony deficiency. Treatment strategies involve cement filling, bone grafting and augments. On the market several solutions are currently available, differing for their shape, thickness and material. While the choice of the shape and the thickness is mainly dictated by the bone defect, no explicit guideline is currently available to describe the best choice of material to be selected for a specific clinical situation. However, the use of different materials could induce different response in term of bone stress and thus changes in implant stability that could worsen long-term implant performance. For these reasons, an investigation about the changes in bone stress in the femur and in the tibia when augments, with different materials and thicknesses was performed. Methods. Different configurations have been separately considered including proximal tibial, distal or/and posterior femoral augments with a thickness of 5, 10 and 15 mm. Apart the control, in which no augments were used, but only the TKA is considered, the augment in all the other configurations were considered made by three different materials: bone cement, to simulate cement filling, tantalum trabecular metal and conventional metal (titanium for the tibia and CoCr for the femoral augments). Each configuration was inserted on a lower leg model including a cruciate-retaining total knee arthroplasty and analyzed by means of finite element analysis applying the max force achieved during walking. The bone stress was investigated in the medial and lateral region of interest close to the augment (with a bone thickness of 10 mm) and in an additional bone region of interest of 50 mm thickness. The bone stress have been compared among the different models and also with respect to the control model. Results. In general, the use of an augment induces a change in bone stress, especially in the region close to the bone cuts. The stiffness of the augment must be as close as possible to the one of the bone. Cement has the best results in terms of bone stress, however, it is only suitable for extremely small defects. Tantalum trabecular metal has results very close to cement and it could be consider a good alternative to cement for any size of defect. Metal (both titanium and CoCr) has the least satisfying results inducing the highest change in bone stress with respect the control. Conclusions. Tibial and femoral bone augments are adopted in case of bone defects that could be present during a revision knee replacement. Several solutions are available on the market in different shapes and materials. However, very few studies are reported to provide possible guidelines. The results of this study demonstrate that material stiffness of the augment must be as close as possible to the one of the bone to achieve the best results

The incidence of rupture of an Achilles tendon constitutes 0,01–0,02%. The infection of the Achilles tendon after operativ repair is a very rare but severe complication. In this study we examined the functional outcome after radical debridement of the Achilles tendon. From 2009 to 2014 we treated 26 patients (22 male, 4 female) with an infection oft he Achilles tendon. In 24 cases the infection was caused after suture of the tendon, in 2 cases the infection was caused by an open injury. The average age was 46,8 (21 to 75). The number of operations the patient had to undergo before admitted to our hospital was 23, in average (with an range from 0 to 9 operations). We performed a radical debridement and the insertion of a local antibiotic carrier. In all cases an at least subtotal resection of the Achilles tendon was necessary. In 10 cases we found Staphylococcus aureus, in 4 cases atleast 2 different types of bacteria. In 2 cases we detected E.coli, in 1 case Enterococcus faecalis and 1 case Bacteroides fragiles. In 6 cases we didn´t succeed in identifying a bacteria despite of a hisological report describing a severe infection. In all cases we achieved a long-lasting stop of the infection. We succeed in 22 cases with just one operation. In 2 cases we had to perform several surgeries(3 Operations and 7 operations) due to extended soft tissue damage of the lower leg and the necessity of a free flap. 22 patients are mobilized in normal shoes, 2 in orthopedic shoes. Because of the building of scartissue we didn´t find a serious impairment of the function despite a subtotal resection of the tendon. The plantar flexion was possible against resistance with reduced strength. Further operative measure such as replacement with other tendons were not required. In order o obtain a durable stop of the infection it is decisive to operate radical. All infected tissue has to be removed. Even a subtotal resection of the Achilles tendon leads to0 a satisfactory functional outcome

(Case) 79-year-old woman. Past history, in 1989, right femur valgus osteotomy. in 1991, THA at left side. Follow-up thereafter. Hyaluronic acid injection for both knee osteoarthritis. (Clinical course)Her right hip pain getting worse and crawling indoors from the beginning of July 2013. We did right hybrid THA at August 2013(posterior approach, TridentHA cup, Exeter stem, Biolox Forte femoral head 28mm). But immediately, she dislocated twice than the third day after surgery because she became a delirium. It has been left by nurse for about 6 hours because of the midnight after the second dislocation. Next morning, check the dislocation limb position, closed reduction wasdone under intravenous anesthesia. As a result of waking up from the anesthesia, and complained of paralysis and violent pain in the right leg backward. A right lower extremity nerve findings, there is pain in the lower leg after surface about the calf, there was no apparent perception analgesia. Toe movement is weak, but the G-toe planter anddorsiflexion possible about M2, and neurological symptoms to relieved by flexion(above 70 degrees) of the right hip joint. Therefore, we thought that she suffered anterior dislocation of the sciatic nerve by the stem neck (retraction), judged to closed reduction was impossible, open reduction surgery was performed after waitingat hip flex position. But paralysis is gradually worsened during waiting surgery, toes movement had become impossible to operating room admission. Sciatic nerve is caught in front of the stem neck as expected, operative findings were able to finally reduction after removing the femoral head after dislocation. Anteversion of the cup was changed to 25 degrees from 15 degrees, and changed to 32mm diameter metal head and polyethylene liner. And we needed Intensive Care Unit(ICU) management after surgery for prevent recurrence of dislocation. Fitted with a hip brace for her, has not been re-dislocation. The sciatic nerve palsy improved in three months after the operation, the patient became able to walk without a cane. (Summary) We experienced a rare case suffered anterior dislocation of the sciatic nerve by the stem neck, and she had a good result after open reduction surgery