Achieving Limb-Length Equality in Femoral Shaft Fractures.

VIDEO AVAILABLE AT: https://ota.org/education/ota-online-resources/video-library-procedures-techniques/achievinglimb-length-equality.

Simultaneous correction of leg length discrepancy and angular deformity of the distal femur with retrograde Precice nails: a retrospective analysis of 45 patients.

BACKGROUND AND PURPOSE: Magnetically controlled motorized intramedullary lengthening nails (ILNs) can be employed for simultaneous correction of angular deformities of the distal femur and leg length discrepancy. This spares typical complications of external fixators but requires precise preoperative planning and exact intraoperative execution. To date, its results are insufficiently reported. We aimed to elucidate the following questions: (i) Is acute angular deformity correction and gradual femoral lengthening via a retrograde ILN a reliable and precise treatment option? (ii) What are the most common complications of treatment? METHODS: Acute angular deformity correction and subsequent gradual lengthening of the distal femur with retrograde ILN was retrospectively analyzed in 45 patients (median patient age: 15 years, interquartile range [IQR] 13-19 and median follow-up: 40 months, IQR 31-50). Outcome parameters were accuracy, precision, reliability, bone healing, and complications of treatment. RESULTS: The median distraction was 46 mm (IQR 29-49), median distraction and consolidation index 0.9 mm/day (IQR 0.7-1.0) and 29 days/cm (IQR 24-43), respectively. The median preoperative mechanical axis deviation (MAD) was 30 mm (IQR 23-39) in the varus cohort and -25 mm (IQR -29 to -15) in the valgus cohort and reduced to a mean of 8 mm (standard deviation [SD] 8) and -3 (SD 10), respectively. Accuracy, precision, and reliability of lengthening were 94%, 95% and 96%, respectively. Accuracy and precision of deformity correction were 92% and 89%, respectively. In total, 40/45 of patients achieved distraction with a difference of less than 1 cm from the initial plan and a postoperative MAD ranging from -10 mm to +15 mm. In 13/45 patients unplanned additional surgeries were conducted to achieve treatment goal with nonunion being the most frequent (4/45) and knee subluxation (3/45) the most severe complication. CONCLUSION: Acute deformity correction and subsequent lengthening of the distal femur with retrograde ILN is a reliable and accurate treatment achieving treatment goal in 89% but unplanned additional surgeries in 29% of patients should be anticipated.

Staples, tension-band plates, and percutaneous epiphysiodesis screws used for leg-length discrepancy treatment: a systematic review and proportional meta-analysis.

BACKGROUND AND PURPOSE: The primary aim of this systematic review and meta-analysis was to evaluate the success rate of 3 different epiphysiodesis techniques with implant usage for the treatment of leg-length discrepancy (LLD) in the pediatric population. The secondary aim was to address effectiveness (final LLD) and the reported complications of staples, tension-band plates (TBP), and percutaneous epiphysiodesis screws (PETS). METHODS: In this systematic review we searched MEDLINE (PubMed), Embase, Cochrane Library, Web of Science and Scopus for studies on skeletally immature patients with LLD treated with epiphysiodesis with an implant. The extracted outcome categories were effectiveness of epiphysiodesis (LLD measurements pre-/postoperatively, successful/unsuccessful) and complications that were graded on severity. RESULTS: 44 studies (2,184 patients) were included. 455 underwent epiphysiodesis with PETS, 578 patients with TBP, and 1,048 with staples. Successful epiphysiodesis was reported in 76% (95% confidence interval [CI] 61-89) with PETS (9 studies), 67% (CI 54-79) with TBP (10 studies), and 51% (CI 28-65) with Blount staples (8 studies). From pooled analysis, the severe complications rate was 7% for PETS, 17% for TBP, and 16% for Blount staples. Angular deformity was reported in 4% after PETS, 10% after TBP, and 17% after Blount staples. CONCLUSION: Our results showed that epiphysiodesis with PETS implants was the most successful technique. PETS had a higher success rate, fewer severe complications, and a lower proportion with angular deformity.

Clinical evaluation of new bone formation during limb lengthening in children using ultrasound combined with superb microvascular imaging.

Aims: Given the possible radiation damage and inaccuracy of radiological investigations, particularly in children, ultrasound and superb microvascular imaging (SMI) may offer alternative methods of evaluating new bone formation when limb lengthening is undertaken in paediatric patients. The aim of this study was to assess the use of ultrasound combined with SMI in monitoring new bone formation during limb lengthening in children. Methods: In this retrospective cohort study, ultrasound and radiograph examinations were performed every two weeks in 30 paediatric patients undergoing limb lengthening. Ultrasound was used to monitor new bone formation. The number of vertical vessels and the blood flow resistance index were compared with those from plain radiographs. Results: We categorized the new bone formation into three stages: stage I (early lengthening), in which there was no obvious callus formation on radiographs and ultrasound; stage II (lengthening), in which radiographs showed low-density callus formation with uneven distribution and three sub-stages could be identified on ultrasound: in Ia punctate callus was visible; in IIb there was linear callus formation which was not yet connected and in IIc there was continuous linear callus. In stage III (healing), the bone ends had united, the periosteum was intact, and the callus had disappeared, as confirmed on radiographs, indicating healed bone. A progressive increase in the number of vertical vessels was noted in the early stages, peaking during stages IIb and IIc, followed by a gradual decline (p < 0.001). Delayed healing involved patients with a prolonged stage IIa or those who regressed to stage IIa from stages IIb or IIc during lengthening. Conclusion: We found that the formation of new bone in paediatric patients undergoing limb lengthening could be reliably evaluated using ultrasound when combined with the radiological findings. This combination enabled an improved assessment of the prognosis, and adjustments to the lengthening protocol. While SMI offered additional insights into angiogenesis within the new bone, its role primarily contributed to the understanding of the microvascular environment rather than directly informing adjustments of treatment.

Radiographic evaluation of robot-assisted versus manual total hip arthroplasty: a multicenter randomized controlled trial.

BACKGROUND: The effectiveness of robot-assisted surgery remains contentious due to the lack of high-quality randomized controlled trials (RCTs) to elevate the level of evidence. We aimed to evaluate the postoperative radiographic outcomes of robot-assisted (RAS-THA) versus manual (M-THA) total hip arthroplasty. METHODS: This multicenter RCT was performed from March 1, 2021 to December 1, 2021. Patients were randomly assigned to routine M-THA or to RAS-THA that used the TRex-RS orthopedic joint surgical navigation system. The primary outcome was to compare the acetabular component orientation, femoral stem alignment, femoral canal fill ratio, and leg length discrepancy between RAS-THA and M-THA using postoperative radiography. Subgroup analyses of the two groups stratified by surgical approach, gender, and BMI were also conducted. RESULTS: Seventy-three participants were randomly allocated to the RAS-THA group, while seventy-two participants were assigned to the M-THA group. Compared to the M-THA group, the RAS-THA group exhibited less variability in the preoperative planning of the vertical center of rotation (VCOR; P < 0.001), demonstrated a significant advantage in femoral stem alignment (P = 0.004), and showed pronounced decreases in inequality and in the variability in leg length discrepancy (P < 0.001). There was no significant difference in the Lewinnek safe-zone ratio (P = 0.081) and the femoral canal fill ratio (P > 0.05) between the two groups. Further subgroup analysis also showed that the RAS-THA group had fewer horizontal center of rotation (HCOR) and leg length differences when stratified by surgical approach, gender, and overweight status. CONCLUSION: This RCT found that, regardless of the surgical approach, gender, or body mass index, RAS-THA can effectively improve the postoperative VCOR and significantly reduce the variability of leg length difference. RAS-THA should be considered an effective method to enhance surgical precision by achieving less variability in challenging patients with leg length discrepancies. TRIAL REGISTRATION: ChiCTR2100044124.

Management of a Proximal Femoral Central Physeal Bar in a 3-Year-Old Child Using a Novel Surgical Technique: A Case Report.

CASE: We present a proximal femoral central physeal bar secondary to femoral neck fracture management, in a 3-year-old boy. He presented with progressive femoral neck deformity and limb length discrepancy. He was managed with a novel technique of bar resection by drilling and polymethylmethacrylate interposition. After 5 years of follow-up, the hip score by Ratliff criteria was good. CONCLUSION: Screw penetration across physis during management of femoral neck fracture can cause growth arrest in a young child. Our technique is useful when physeal bar is central and linear. It can allow sufficient growth and remodeling to restore a near-normal hip both radiologically and clinically.

Effects of lower limb length discrepancy on spinopelvic compensation following total hip arthroplasty in patients with developmental dysplasia of the hip.

BACKGROUND: Limited research has examined the impact of lower limb length discrepancy (LLLD) alteration on spinopelvic compensation in individuals with developmental dysplasia of the hip (DDH). This study aimed to investigate the effects of LLLD on spinopelvic compensation following total hip arthroplasty (THA) and elucidate the complex biomechanical adaptations in the spinopelvic structures. METHODS: A retrospective review of DDH patients undergoing THA from January 2014 to December 2021 categorized individuals with Crowe type I and II into the low dislocation group (LDG, n = 94) and those with Crowe type III and IV into the high dislocation group (HDG, n = 43). Demographic data, as well as preoperative, postoperative, and last follow-up imaging data, including lower limb length (LLL), sacral obliquity (SO), iliac obliquity (IO), hip obliquity (HO), Cobb angle, apical vertebral translation (AVT), and coronal decompensation (CD), were collected for analysis. RESULTS: Patients in the LDG had a significantly higher surgical age and shorter disease duration (P<0.05). In LDG, patients exhibited substantial postoperative reductions in LLLD, SO, IO, and HO (P<0.05), while Cobb Angle, AVT, and CD showed no statistically significant changes (P>0.05). The variation in LLLD correlated significantly with the variations in SO, IO, and HO (P<0.05). Postoperative outcomes in the HDG demonstrated marked decreases in LLLD, SO, IO, HO, and CD (P<0.05), with no significant change in Cobb angle and AVT (P>0.05). The variation in LLLD correlated significantly with the variations in SO, IO, HO, and CD (P<0.05). CONCLUSIONS: THA effectively reduces LLLD in patients with DDH, and the variation in LLLD correlates meaningfully with the recovery of spinopelvic compensatory mechanisms.

The Effect of Knee Height Asymmetry on Gait Biomechanics.

BACKGROUND: Though the primary goal for limb length discrepancy (LLD) management is to equalize the leg lengths, symmetry between corresponding long bones is usually not achieved, leading to knee height asymmetry (KHA). To date, there is minimal information on what effect KHA has on gait biomechanics and joint loading. Thus, the purpose of this study is to determine the impact of KHA on gait biomechanics. METHODS: Seventeen subjects with KHA after limb equalizing surgery and 10 healthy controls were enrolled. Subjects participated in 3D gait analysis collected using self-selected speed. Lower extremity kinematics, kinetics, work generated/absorbed, and total work were calculated. Standing lower limb x-rays and scanograms were used to measure LLD and calculate the tibia-to-femur (TF) ratio for each limb. Two sample t tests were used to compare differences in standing LLD, TF ratio, and work between groups. Bivariate correlation using Pearson correlation coefficients was conducted between TF ratio and total mechanical work, as well as between knee height asymmetry indices and total work asymmetry (α=0.05). RESULTS: Among participants, there were no differences between LLD; however, there were differences between TF ratio and knee height asymmetry. We found a nonsignificant relationship between TF ratio and total mechanical work for individual lower extremities. Therefore, the length of individual bones (TF ratio) relative to each other within the individual lower extremity was not associated with the amount of work produced. However, when a difference exists between sides (asymmetry, ie, TF ratio asymmetry), there were associated differences in work (work asymmetry) produced between sides (r=0.54, P =0.003). In other words, greater knee height asymmetry between limbs resulted in more asymmetrical mechanical work during walking. CONCLUSIONS: These findings may have implications for the management of LLD. Asymmetrical total mechanical work could lead to atypical joint loading during gait. Surgeons may want to consider prioritizing achieving knee height symmetry as a postoperative goal when correcting limb length discrepancy. LEVEL OF EVIDENCE: Level III, Case Control Study.

Leg length discrepancies (LLD): An etiology to be considered in its proper measure. A critical and historical review.

INTRODUCTION: Studies of leg-length discrepancies (LLD) have been the subject of debate for almost 200 years. A large number of studies have emerged, most frequently using assessment criteria based on painful symptoms or joint damage. DEVELOPMENT: While many authors argue for a threshold of 10-20 mm to establish a link between pain and LLD, most publications based on radiography show lesion stigmata on lumbar, hip and knee joints as early as 6 mm. This would be linked to comorbidities. DISCUSSION: Some studies argue forcefully that leg-length correction below 20 mm is of no benefit. The authors of the present article, on the other hand, evoke the notion of lesion risks in the absence of correction, even for small deviations in the presence of certain associated factors and according to their importance. CONCLUSION: The authors argue for the need to define in the future a lesion significance score that would not be correlated to painful symptomatology, but rather to the presence of co-morbidities such as age, anatomical variability, sports practice and/or patients' professional activities. Other parameters, such as mobility, should also be taken into consideration, while gender, height and weight do not appear to be significantly related.

Accuracy of two-dimensional digital planning in uncemented primary hip arthroplasty: monocentric analysis of eight hundred implants.

PURPOSE: In the last decades, there has been a refinement in total hip arthroplasty, which allowed surgeons to achieve the highest performance and better patient outcomes. Preoperative planning in primary hip arthroplasty is an essential step that guides the surgeon in restoring the anatomy and biomechanics of the joint. This study aims to evaluate the accuracy of the 2D digital planning, considering cup sizing, stem sizing, and limb length discrepancy. Additionally, we conducted a multivariable analysis of demographic data and comorbidities to find factors influencing preoperative planning. METHODS: This retrospective study analyzed the planning accuracy in 800 consecutive uncemented primary total hip arthroplasty. We compared the preoperatively planned total hip arthroplasty with postoperative results regarding the planned component size, the implanted size, and the lower limb length restoration. Therefore, we investigated factors influencing planning accuracy: overweight and obesity, sex, age, past medical history, comorbidities, and implant design. All the surgeries were performed in the posterolateral approach by one expert surgeon who did the preoperative planning. The preoperative planning was determined to be (a) exact if the planned and the implanted components were the same size and (b) accurate if exact ± one size. The restoration of postoperative limb length discrepancy was classified into three groups: ± 3 mm, ± 5 mm, and ± 10 mm. This assessment was performed through a digital method 2D based on a standard hip X-ray. RESULTS: This court of 800 implants showed that planning was exact in 60% of the cups and 44% of the stems and was accurate in 94% of the cups and 80% of the stems. The postoperative limb length discrepancy was ± 3 mm in 91% and ± 5 mm in 97%. CONCLUSIONS: This study showed preoperative 2D digital planning great precision and reliability, and we demonstrated that it was accurate in 94% of the cups and 80% of the stems. Therefore, the preoperative limb length discrepancy analysis was essential to guarantee the recovery of the operated limb's correct length.

[Correlation between femoral offset, rotation center and leg length discrepancy after total hip arthroplasty based on digital analysis].

OBJECTIVE: CT scans combined with Mimics software were used to measure femoral offset (FO), rotation center height (RCH) and lower leg length discrepancy (LLD) following total hip arthroplasty (THA), and the relationship between FO, RCH and LLD after THA is discussed. METHODS: Retrospective analysis was performed on 40 patients with unilateral THA who met standard cases from October 2020 to June 2022. There were 21 males and 19 females, 18 patients on the left side and 22 patients on the right side, aged range from 30 to 81 years old, with an average age of (58.90 ±14.13) years old, BMI ranged from 17.3 to 31.5 kg·m-2 with an average of (25.3±3.4) kg·m-2. There were 30 cases of femoral head necrosis (Ficat type Ⅳ), 2 cases of hip osteoarthritis (Tönnis type Ⅲ), 2 cases of developmental hip dislocation combined with end-stage osteoarthritis (Crowe type Ⅲ), and 6 cases of femoral neck fracture (Garden type Ⅳ). Three-dimensional CT reconstruction of pelvis was taken preoperative and postoperative, and three-dimensional reconstruction model was established after processing by Mimics software. FO, RCH and LLD were measured on the model. The criteria for FO reconstruction were as follows:postoperative bilateral FO difference less than 5 mm;the standard for equal length of both lower limbs was as follows:postoperative LLD difference less than 5 mm. RESULTS: Bilateral FO difference was positively correlated with LLD (r=0.744, P<0.001). Chi-square test was performed between the FO reconstructed group and the non-reconstructed eccentricity group:The results showed that the isometric ratio of lower limbs in the FO reconstructed group was significantly higher than that in the FO reconstructed group (χ2=6.320, P=0.012). The bilateral RCH difference was significantly negatively correlated with LLD(r=-0.877, P<0.001). There is a linear relationship between bilateral FO difference and bilateral RCH difference and postoperative LLD, and the linear regression equation is satisfied:postoperative LLD=0.038x-0.099y+0.257(x:postoperative bilateral FO difference, y:postoperative bilateral RCH difference; Unit:cm), F=77.993, R2=0.808, P=0.009. CONCLUSION: After THA, LLD increased with the increase of FO and decreased with the increase of RCH. The effect of lower limb isometric length can be obtained more easily by reconstruction of FO. There is a linear relationship between the bilateral FO difference and the bilateral RCH difference after THA and LLD, and the regression equation can provide a theoretical reference for judging LLD.

Lengthening in congenital posteromedial bowing of tibia: a follow-up series at skeletal maturity.

PURPOSE: Congenital posteromedial bowing (CPMB) of tibia is a rare, usually self-resolving condition that is present at birth. The data on the long-term outcome of lengthening, choice of fixator, outcome in early and late age groups, and complications is sparse, hence the need for this study. METHODS: This retrospective study included 93 patients with 94 affected legs from 1991 to 2023. The patients were categorized into early (under 10 years) and late (10 years or above) intervention groups. Eighteen patients with nineteen lengthening episodes who attained skeletal maturity made the basis of this study and will be discussed in detail. RESULTS: The outcome for the lengthening group at maturity was satisfactory, with 5.53 cm of average length gained per lengthening episode, a mean LLD of 0.31 cm at final follow-up, a mean age of 23.63 years (range 14-38 years), and an average follow-up of 12.51 years (range 3-28 years) post-lengthening, but the procedure was associated with difficulties like ankle stiffness, tibial valgus, pin tract infections, and fractures through regenerate. CONCLUSION: This study represents a large single-centre series on CPMB. We recommend that surgery for lengthening should be done at an older age, close to skeletal maturity, wherever possible to reduce the risk of repeat lengthening procedures. Based on our experience, we recommend the use of a circular fixator. Uniplanar distractors should have an adequate number and spread of Schanz screws in each segment to reduce the risk of valgus malalignment of distracting segments of bone.

Limb salvage reconstruction of the lower limb with complex ankle arthrodesis and magnetic internal lengthening nail.

PURPOSE: With advances in orthopedic implants, the use of intramedullary lengthening devices has gained increasing popularity as an alternative technique compared to lengthening with external fixators, with alleged comparable or better outcomes. The aim of this study is to report our single-center technique and outcomes of combined ankle arthrodesis and proximal tibial lengthening using external fixator with a motorized intramedullary nail, respectively. METHOD: Fourteen patients with post-traumatic advanced ankle arthritis underwent staged ankle arthrodesis with external fixator and proximal tibial lengthening using the PRECICE® ILN. Amount of shortening, length achieved, bone healing index, infection rate, ankle fusion rate, and ASAMI score were evaluated. RESULTS: The average age was 44 years old (range, 30-62). The mean follow up is 70 months (range, 43-121.4). The average amount of limb shortening for patients after ankle fusion was 36.7 mm (18-50) while lengthening was 35.9 mm (range, 18-50). Patients had the nail implanted for an average of 479 days (range, 248-730). Ankle fusions were healed in an average of 178.3 days. There were no surgical infections. All osteotomy-lengthening sites healed after an average 202 days (106-365). The mean bone healing index (BHI) was 56.0 days/cm (21.2-123.6) among the whole cohort. There were no cases of nonunion. ASAMI bone scores were excellent or good among all patients. CONCLUSION: Ankle arthrodesis with external fixation along with proximal tibial lengthening using motorized IMN yielded high rates of fusion and successful lengthening. This technique could be offered as a reasonable alternative to using external fixation for both purposes. LEVEL OF EVIDENCE: Level IV, Retrospective cohort study.

Intramedullary nailing of femoral shaft fractures: an analysis of rotational malunions using 3D EOS.

PURPOSE: Rotational malalignment and leg length discrepancy after intramedullary nailing of femoral shaft are frequent. This study has three objectives: evaluate the rate of femoral rotational malalignment and leg length discrepancy using EOS imaging after antegrade intramedullary nailing of femoral shaft fracture, find a relevant clinical examination to detect malrotation and identified risk factors. METHODS: We performed a retrospective single-centre study between January 2014 and January 2022. Fifty-eight patients were clinically and radiographically assessed at a minimum of three months. RESULTS: The femoral rotation of the operated side was significantly greater by a mean of 15.4° in internal rotation compared to the healthy side. There was no statically significant difference for the femoral length (p = 0.08). CONCLUSION: When using EOS stereography following antegrade intramedullary nailing of post-traumatic diaphyseal femur fractures, a statistically significant difference of more than 15.4° in internal rotation was found for femoral rotation on the operated side compared to the healthy side.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [B. Poirot] Last name [Seynaeve]. Also, kindly confirm the details in the metadata are correct.The last name of the first author was corrected : Given name = B. and last name = Poirot Seynaeve The details in matadata are correct LEVEL OF EVIDENCE: III.

Limb Length Discrepancy After Intraosseous Line Malpositioning: A Case Report.

CASE: We will present the case of a 6-year-old girl who presented with a 3-cm limb length discrepancy after intraosseous line placement at age 14 months without other known history of trauma or infection to account for the growth arrest. Imaging revealed a left proximal tibial physeal bar amenable to surgical resection with autologous lipotransfer. At 10 months postoperatively, physical examination and imaging demonstrated a stable 3-cm leg length discrepancy with an interval increase in the length of the left tibia in proportion to the growth of the right side with an increase in valgus alignment that will continue to be monitored and addressed as indicated. CONCLUSION: Pediatric intraosseous line placement presents unique challenges and can ultimately lead to physeal injury and growth arrest in the case of malpositioning.

A novel measurement approach to dynamic change of limb length discrepancy using deep learning and wearable sensors.

The accurate identification of dynamic change of limb length discrepancy (LLD) in non-clinical settings is of great significance for monitoring gait function change in people's everyday lives. How to search for advanced techniques to measure LLD changes in non-clinical settings has always been a challenging endeavor in recent related research. In this study, we have proposed a novel approach to accurately measure the dynamic change of LLD outdoors by using deep learning and wearable sensors. The basic idea is that the measurement of dynamic change of LLD was considered as a multiple gait classification task based on LLD change that is clearly associated with its gait pattern. A hybrid deep learning model of convolutional neural network and long short-term memory (CNN-LSTM) was developed to precisely classify LLD gait patterns by discovering the most representative spatial-temporal LLD dynamic change features. Twenty-three healthy subjects were recruited to simulate four levels of LLD by wearing a shoe lift with different heights. The Delsys TrignoTM system was implemented to simultaneously acquire gait data from six sensors positioned on the hip, knee and ankle joint of two lower limbs respectively. The experimental results showed that the developed CNN-LSTM model could reach a higher accuracy of 93.24% and F1-score of 93.48% to classify four different LLD gait patterns when compared with CNN, LSTM, and CNN-gated recurrent unit(CNN-GRU), and gain better recall and precision (more than 92%) to detect each LLD gait pattern accurately. Our model could achieve excellent learning ability to discover the most representative LLD dynamic change features for classifying LLD gait patterns accurately. Our technical solution would help not only to accurately measure LLD dynamic change in non-clinical settings, but also to potentially find out lower limb joints with more abnormal compensatory change caused by LLD.

Direct anterior approach with conventional instruments versus robotic posterolateral approach in elective total hip replacement for primary osteoarthritis: a case-control study.

BACKGROUND: The purpose of this study is to compare peri-operative and short-term outcomes in patients who underwent elective total hip replacement (THA) for primary osteoarthritis (OA) with direct anterior approach (DAA) versus a pair-matched cohort of patients who underwent robotic-assisted THA with posterolateral approach. MATERIALS AND METHODS: Data from consecutive patients who underwent elective hip replacement from 2021 to 2023 for primary OA were retrospectively retrieved and divided into two groups: the DAA group, who underwent THA with the DAA approach using conventional instruments, and the robotic posterolateral (R-PL group), who underwent robot arm-assisted THA with the posterolateral approach. Comparative assessed outcomes were: operative time, radiographical implant positioning, intake of rescue analgesics, blood loss, transfusion rate, leg length discrepancy and functional outcomes (Harris hip score and forgotten joint score). RESULTS: A total of 100 pair-matched patients were retrieved with a mean age of 66.7 ± 10.7 (range: 32-85) years and a mean follow-up of 12.8 ± 3.6 (range: 7-24) months. No differences in patients' characteristics were detected. Patients in the R-PL group required less rescue tramadol (p > 0.001), ketorolac (p = 0.028) and acetaminophen (p < 0.001). There was no significant difference in the operative time between (MD = 5.0 min; p = 0.071). Patients in the DAA group had significantly lower Hb levels at day 1 (p = 0.002) without significant differences in transfusion rate (p = 0.283). Patients in the R-PL group had shorter length of stay (LOS) with a mean difference of 1.8 days [p < 0.001; 95% confidence interval (CI) 1.4-2.3]. No difference in clinical outcomes was found [leg length discrepancy (LLD), p = 0.572; HHS, p = 0.558; forgotten joint score (FJS), p = 0.629]. No radiographical differences were measured in cup inclination (MD = 2.0°, p = 0.069), malpositioning [odd ratio (OR) = 0.2; p = 0.141], stem alignment (OR = 0.3; p = 0.485) and stem sizing (OR = 1.5; p = 1.000). There was no difference in complication rate except for lateral femoral cutaneous nerve damage, which was higher in DAA group (p < 0.001). CONCLUSIONS: R-PL and DAA THA had comparable short-term clinical and radiological outcomes along with similar complication rates. The R-PL group showed significantly lower Hb drop, rescue analgesic consumption and shorter LOS. This is a preliminary study and no strong recommendation can be provided. Further prospective randomized trials are requested to further investigate the cost-effectiveness of robotic surgery in THA. LEVEL OF EVIDENCE: Level IV, case-control study.

Clinical compatibility of magnetic resonance imaging with magnetic intramedullary nails: a feasibility study.

INTRODUCTION: The use of magnetic resonance imaging (MRI) with a magnetic intramedullary lengthening nail in place is contraindicated per the manufacturer due to the concern of implant activation and migration. A prior in vitro study did not confirm these complications only noting that a 3.0 T MRI weakened the internal magnet. Therefore, a retrospective analysis of patients who underwent an MRI with a magnetic nail in place was performed to determine if any adverse effects occurred in the clinical setting. MATERIALS AND METHODS: A retrospective review of all patients who underwent an MRI with a magnetic lengthening nail in place was performed. The time spent being imaged in the MRI, number of times the patient entered the MRI suite, and the images obtained were recorded. Radiographs were performed before and after the MRI to determine if any hardware complications occurred. The patients were monitored for any adverse symptoms while they were in the suite. RESULTS: A total of 12 patients with 13 nails were identified. Two patients underwent imaging with a 3.0 T MRI while the remaining 10 underwent imaging with a 1.5 T MRI. Each patient entered the MRI suite 2.1 times and spent an average of 84.7 min being imaged in the MRI (range 21-494). No patients noted any adverse symptoms related to the nail while in the suite and no hardware complications were identified. CONCLUSION: MRI appears to be safe with a magnetic nail in place and did not result in any complications. Given the manufacturer's recommendations, informed consent should be obtained prior to an MRI being performed and a 3.0 T MRI should be avoided when possible if further activation of the nail is required.

Anatomical leg length discrepancy in children: Can it be accurately determined using 3-D motion capturing?

BACKGROUND: Leg length discrepancy (LLD) is common in youth and is cause by several conditions. Long leg X-rays is the gold standard technique of measuring LLD. It is highly accurate and reliable compared to clinical method, but expose the subject to radiation. Instrumented Gait Analysis (IGA) serves not only as a means to measure joint kinematics during gait but also as a valuable tool for assessing Leg Length Discrepancy (LLD) while standing. RESEARCH QUESTION: The purpose of this study was to compare different methods of determining the LLD in paediatric population. We hypothesize that IGA using joint centres is more accurate and precise than the tape measurement. METHODS: Thirty-one patients with mean age 12.3 (SD=2.4) years were retrospectively included in the study. Their LLD varied between 0 and 36 mm. Three methods for determining LLD were compared to radiography using Bland-Altman analysis: 1. Tape measurement, 2. IGA, summarizing the distance from the spina iliaca anterior superior to the medial malleolus marker via the medial knee condyle marker. 3. IGA, summarizing distances between ankle, knee, and hip joints centres where the latter is calculated with different equations. RESULTS: The IGA joints method performed better than the tape measurement or IGA markers method. The equations of Davis calculating the hip joint centre had the highest accuracy with mean difference to radiography of 0.7 mm (SD=6.3). The simple Harrington method resulted in a slightly reduced accuracy but higher precision 0.9 mm (SD=6.2). The Harrington method with leg length as input was less accurate 1.0 mm (SD=6.7), but was still considerably better than the tape measurement 1.8 mm (SD=7.0) or IGA markers method 1.1 mm (SD=11.5). SIGNIFICANCE: Determining LLD with IGA using the distances between ankle, knee and hip joints centres is a feasible method that can be applied in clinical practice to calculate LLD.

Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years.

BACKGROUND AND PURPOSE: Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications. PATIENTS AND METHODS: In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12-15) were available for analysis. The median follow-up was 29 months (IQR 27-37) after nail implantation. RESULTS: The median distraction length per segment was 49 mm (IQR 47-51) with a median distraction index of 1.0 mm/day (IQR 0.9-1.0), and a median consolidation index of 20 days/cm (IQR 17-23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation. CONCLUSION: The method is reliable and accurate with few complications.