Incidence and management of secondary deformities after megaendoprosthetic proximal femur replacement in skeletally immature bone sarcoma patients.

INTRODUCTION: Megaendoprosthetic reconstruction of bone defects in skeletally immature patients has led to the development of unique complications and secondary deformities not observed in adult patient cohorts. With an increasing number of megaendoprosthetic replacements performed, orthopedic oncologists still gain experience in the incidence and type of secondary deformities caused. In this study, we report the incidence, probable cause and management outcome of two secondary deformities after megaendoprosthetic reconstruction of the proximal femur: hip dysplasia and genu valgum. MATERIALS AND METHODS: Retrospective analysis of 14 patients who underwent primary and/or repeat reconstruction/surgery with a megaendoprosthetic proximal femur replacement between 2018 and 2022. RESULTS: Mean patient age was 9.1 years (range 4-17 years). Stress shielding was observed in 71.4%. Hip dislocation was the most frequent complication (50%). While four dislocations occurred without an underlying deformity, secondary hip dysplasia was identified in 58.3% (n = 7/12) of intraarticular resections and reconstructions, leading to dislocation in 71.4% (n = 5/7). A genu valgum deformity was observed in 41.6% (n = 5/12). The incidence of secondary hip dysplasia and concomitant genu valgum was 42.9% (n = 3/7). Triple pelvic osteotomy led to rebound hip dysplasia in two cases (patients aged < 10 years), whereas acetabular socket replacement led to stable hip joints over the course of follow-up. Temporary hemiepiphyseodesis was applied to address secondary genu valgum. CONCLUSIONS: Patients aged < 10 years were prone to develop secondary hip dysplasia and genu valgum following proximal femur replacement in this study. Management of secondary deformities should depend on remaining skeletal growth. Stress shielding was observed in almost all skeletally immature patients.

Registration based assessment of femoral torsion for rotational osteotomies based on the contralateral anatomy.

BACKGROUND: Computer-assisted techniques for surgical treatment of femoral deformities have become increasingly important. In state-of-the-art 3D deformity assessments, the contralateral side is used as template for correction as it commonly represents normal anatomy. Contributing to this, an iterative closest point (ICP) algorithm is used for registration. However, the anatomical sections of the femur with idiosyncratic features, which allow for a consistent deformity assessment with ICP algorithms being unknown. Furthermore, if there is a side-to-side difference, this is not considered in error quantification. The aim of this study was to analyze the influence and value of the different sections of the femur in 3D assessment of femoral deformities based on the contralateral anatomy. MATERIAL AND METHODS: 3D triangular surface models were created from CT of 100 paired femurs (50 cadavers) without pathological anatomy. The femurs were divided into sections of eponymous anatomy of a predefined percentage of the whole femoral length. A surface registration algorithm was applied to superimpose the ipsilateral on the contralateral side. We evaluated 3D femoral contralateral registration (FCR) errors, defined as difference in 3D rotation of the respective femoral section before and after registration to the contralateral side. To compare this method, we quantified the landmark-based femoral torsion (LB FT). This was defined as the intra-individual difference in overall femoral torsion using with a landmark-based method. RESULTS: Contralateral rotational deviation ranged from 0° to 9.3° of the assessed femoral sections, depending on the section. Among the sections, the FCR error using the proximal diaphyseal area for registration was larger than any other sectional error. A combination of the lesser trochanter and the proximal diaphyseal area showed the smallest error. The LB FT error was significantly larger than any sectional error (p < 0.001). CONCLUSION: We demonstrated that if the contralateral femur is used as reconstruction template, the built-in errors with the registration-based approach are smaller than the intraindividual difference of the femoral torsion between both sides. The errors are depending on the section and their idiosyncratic features used for registration. For rotational osteotomies a combination of the lesser trochanter and the proximal diaphyseal area sections seems to allow for a reconstruction with a minimal error.

A novel morphological classification for the femoral notch based on MRI: a simple and effective assessment method for the femoral notch.

OBJECTIVE: To propose a novel morphological classification method for notches, which may provide new evidence for notchplasty based on the three-dimensional (3D) features of notches and the risk of anterior cruciate ligament (ACL) injury. MATERIALS AND METHODS: Three hundred individuals in total were included in our study, including 150 patients with ACL ruptures (75 males and 75 females) and 150 age- and gender-matched individuals without ACL ruptures. The notches were divided into four types according to the notch widths at the notch inlet, outlet, and ACL attachment based on the preoperative MRI, the notch volume was calculated, and the risk of ACL injury was compared. The surgical records were reviewed and whether these cases performed notchplasty were collected. RESULTS: The inlet-and-outlet stenosis notch type was associated with smaller notch volume (P = 0.007) and a higher risk of ACL injury (P < 0.001). There were no significant differences in morphological distribution between males and females. The rate of notchplasty in inlet-and-outlet stenosis type was higher than the others. CONCLUSIONS: The new morphological classification method efficiently reflected the association of the notch shape with the 3D notch volume and the risk of ACL injury. The knees with the inlet-and-outlet stenosis notch type and smaller notch volume tended to have a higher risk of ACL injury. Level of evidence Level III, case-control study.

Ultrasonographic Assessment of Femoral Torsion Angle Based on Tilting Angles of Femoral Neck and Condylar Axis.

Femoral anteversion has been assessed with ultrasound using femoral neck tilting angle (FN-TA); however, femoral torsion angle (FTA), which is defined using FN-TA and condylar axis tilting angle, has not been assessed with ultrasound. This study aimed to establish the ultrasonographic assessment of FTA (US-FTA) by comparing data obtained through US-FTA and computed tomography (CT). Twenty-one patients (age range, 38-82 y) with 21 intact hips were included. In the US-FTA, the femoral head and anterior tubercle of the greater trochanter were used as bony landmarks. The intra-rater and inter-rater reliabilities and standard error of measurement (SEM) of US-FTA were 0.994 (SEM 0.93) and 0.994 (SEM 0.94), respectively. A strong agreement was found between FTA variables obtained with ultrasound and CT (R = 0.939, p < 0.001). Ultrasound is useful and can be a valid alternative to CT for the evaluation of the femoral torsion angle without radiation exposure.

Outcomes and subjective assessment of rotation-plasty in patients with proximal femoral focal deficiency.

This study presents outcomes of rotation-plasty for unilateral proximal femoral focal deficiency in the adolescent population. The function, timing of knee fusion, and complications were presented as well as patients' assessment of their function and appearance. Eight patients, aged 8.37 years (range: 3-16 years) during surgery, were evaluated. The mean follow-up duration was 9.25 years (range: 6-12 years). At follow-up, all the patients were pain free and able to ambulate outdoors. Complications included derotation of the foot in five patients, necessitating a re-rotation osteotomy in two. All patients accepted their appearance, considering the rotation-plasty beneficial for their functional status.

A Simple Method for Measurement of Femoral Anteversion-Validation and Assessment of Reproducibility.

OBJECTIVES: To propose a simple method for measurement of femoral anteversion (AV) with a conventional fluoroscope, to evaluate the interobserver and intraobserver reliability of this method on the basis of human cadaver femurs, and to validate such method on the basis of computed tomography (CT). METHODS: Fourteen human cadavers with 28 intact femurs were included in the study. Three blinded observers measured femoral AV of the specimen with a fluoroscope. The session was repeated 8 weeks later and CT of the femurs were performed. Mean AV values and the difference between single and mean AV values were calculated. Interobserver/intraobserver reliability of the proposed method was assessed. Correlation between AV values measured with fluoroscope and CT was calculated. RESULTS: Mean AV was 18.1° when measured with fluoroscope and 19.2° when measured with CT. Mean differences between single AV values were 2.2° with fluoroscope and 2.5° with CT. The mean maximum observer variation per specimen was 8.8°. Interobserver reliability was excellent (intraclass correlation coefficient: 0.853) and intraobserver reliability was good (intraclass correlation coefficient: 0.682). A high correlation was found between AV values measured with fluoroscope and CT (rho = 0.739, P < 0.01). CONCLUSION: The presented technique allows reliable and simple measurement of femoral AV with a conventional fluoroscope. The mean interobserver variation is comparable to what has been reported for CT. Maximum interobserver variation was <15° in all specimens. A clinical study will be necessary to prove the value of this technique for intraoperative adjustment of femoral AV according to the intact contralateral side.

Protocol for CT in the position of discomfort: preoperative assessment of femoroacetabular impingement - how we do it and what the surgeon wants to know.

INTRODUCTION: The use of computed tomography of the hip in a position of discomfort (CT-POD) in combination with 2D and 3D surface rendering is a technique increasingly used to aid in the assessment and confirmation of femoral and acetabular bony abnormalities related to femoroacetabular impingement. The purpose of this article is to describe this dynamic method of assessment. METHODS: Patients referred by orthopaedic surgeons for assessment of femoroacetabular impingement as part of preoperative planning and patients who required postoperative assessment of residual bony abnormalities were selected. RESULTS: This article describes the CT-POD technique and the information required by the referring surgeon. CONCLUSION: CT-POD is a new technique that provides valuable preoperative and postoperative information to the surgeon.

Reliability of the assessment of lower limb torsion using computed tomography: analysis of five different techniques.

OBJECTIVE: Various methods have been described to define the femoral neck and distal tibial axes based on a single CT image. The most popular are the Hernandez and Weiner methods for defining the femoral neck axis and the Jend, Ulm, and bimalleolar methods for defining the distal tibial axis. The purpose of this study was to calculate the intra- and interobserver reliability of the above methods and to determine intermethod differences. METHODS: Three physicians separately measured the rotational profile of 44 patients using CT examinations on two different occasions. The average age of patients was 36.3 ± 14.4 years, and there were 25 male and 19 female patients. After completing the first two sessions of measurements, one observer chose certain cuts at the levels of the femoral neck, femoral condylar area, tibial plateau, and distal tibia. The three physicians then repeated all measurements using these CT cuts. RESULTS: The greatest interclass correlation coefficients were achieved with the Hernandez (0.99 intra- and 0.93 interobserver correlations) and bimalleolar methods (0.99 intra- and 0.92 interobserver correlations) for measuring the femoral neck and distal tibia axes, respectively. A statistically significant decrease in the interobserver median absolute differences could be achieved through the use of predefined CT scans only for measurements of the femoral condylar axis and the distal tibial axis using the Ulm method. The bimalleolar axis method underestimated the tibial torsion angle by an average of 4.8° and 13° compared to the Ulm and Jend techniques, respectively. CONCLUSIONS: The methods with the greatest inter- and intraobserver reliabilities were the Hernandez and bimalleolar methods for measuring femoral anteversion and tibial torsion, respectively. The high intermethod differences make it difficult to compare measurements made with different methods.

Cruciate ligaments in proximal femoral focal deficiency: arthroscopic assessment.

BACKGROUND: Because there is limited information concerning the cruciate ligaments in proximal femoral focal deficiency, knee arthroscopy was used to identify the changes of cruciate ligaments and their relation to the different types of this deficiency. METHODS: Knee arthroscopy was performed in 21 consecutive patients with deficiency types III, IV, VII-IX using the Pappas classification. A new classification of the knee was created. It contains types I, II, III according to the findings of the anterior cruciate ligament (ACL) (type I: normal, type II: hypoplasia, type III: aplasia) and 3 subtypes A, B, C according to the findings of the posterior cruciate ligament (PCL) (type A: normal, type B: hypoplasia, type C: aplasia), respectively. Instrumented and radiologic drawer testing was provided additionally in 2010. RESULTS: The changes of the cruciate ligaments were found in all but 1 patient. Type I was found in only 2 patients. In 1, both cruciate ligaments were intact (type IA). In the other patient, the ACL was intact, but the PCL was absent (type IC). Hypoplastic ACLs (type II) were found in 4 patients, namely in 3 patients with normal PCLs (type IIA), whereas in 1 patient the PCL was absent (type IIC). In the majority of patients, the ACLs completely failed (type III, 15 patients). Absence of both cruciate ligaments was found in 8 patients (type IIIC). PCLs were intact in 4 patients (IIIA) or were hypoplastic in 3 patients (IIIB), respectively. Instrumental drawer testing was not reliable in patients of our group. Radiologic testing showed a posterior shift of the tibia in the majority of patients on the affected side. Anterior and posterior drawer tests were increased in a majority of patients, but did not directly correlate to the presence/absence of cruciate ligaments. CONCLUSIONS: Variable changes of the cruciate ligaments were found in all but 1 patient with proximal femoral focal deficiency. These changes were not related to the type of Pappas classification. Despite the lower clinical relevance of the changes in majority of patients, imaging of cruciate ligaments is recommend before lengthening of the extremity to avoid dislocation of the knee. LEVEL OF EVIDENCE: I - Testing of previously developed diagnostic criteria in series of consecutive patients.

Bone stiffness in children: part I. In vivo assessment of the stiffness of femur and tibia in children.

Although there are many publications concerning the mechanical behavior of adult bone, there are few data about mechanical properties of children's bone. In vivo bone stiffness measurement with Orthometer device has been validated and extensively used in adults to assess bone healing after fracture or lengthening. We hypothesized that in vivo stiffness measurement with Orthometer was applicable in children and was correlated with age, height, body weight, and corpulence index. The purpose was to establish baseline stiffness values for femur and tibia in growing children.Sixteen bone measurements (7 femurs and 9 tibias) were obtained during application of an external fixator for leg lengthening in 11 children aged between 5.5 and 16.7 years. A 3-point bending test with an Orthometer was carried out on the intact bone (before osteotomy) under general anesthesia. The anteroposterior stiffness measurement was successful in all children of the series, aged from 5.5 to 16.7 years. A wide variation of femoral and tibial bone stiffness values were observed. The use of a unique value as in adults as the end point of bending stiffness during bone healing process is not possible for children. The anteroposterior bone stiffness was found to have linear correlation with children's height and body weight, but not with age and corpulence indexes. The original data obtained by this study will give a stiffness reference for height and weight and could be useful as reference values for monitoring of healing process after fracture or limb lengthening.

Dysplasia of the cruciate ligaments: radiographic assessment and classification.

BACKGROUND: A common pathologic finding in the knee associated with congenital longitudinal deformity is aplasia of one or both cruciate ligaments. We performed a radiographic analysis to assess the changes in the femoral intercondylar notch and the tibial eminence in relation to the status of the cruciate ligaments. METHODS: Thirty-four knees in thirty-one patients with longitudinal congenital deficiency of the lower limb were evaluated. The cruciate ligaments and the associated abnormalities of the distal aspect of the femur and the proximal aspect of the tibia were evaluated with use of magnetic resonance imaging and a tunnel view radiograph. RESULTS: We differentiated three main types of dysplasia of the cruciate ligaments with typical associated changes. In type I, partial closure of the femoral intercondylar notch and hypoplasia of the tibial eminence are observed and the anterior cruciate ligament is hypoplastic or aplastic. In type II, these findings are accentuated and there is additional hypoplasia of the posterior cruciate ligament. In type III, the femoral intercondylar notch and the tibial eminence are completely absent and there is aplasia of both cruciate ligaments. CONCLUSIONS: We delineated three types of congenital deficiency of the cruciate ligaments and found corresponding morphologic changes of the femoral notch and the tibial eminence, which can be observed on tunnel view radiographs. Thus, the diagnosis and differentiation between aplasia of one or both cruciate ligaments and between congenital and trauma-induced absence of the cruciate ligaments may be made by interpreting plain radiographs.

Value of magnetic resonance imaging in early assessment of proximal femoral focal deficiency (PFFD).

Proximal femoral focal deficiency (PFFD) is a developmental defect of the proximal femur and acetabulum. PFFD includes a spectrum of findings ranging from mild femoral shortening with varus deformity to complete absence of both the acetabulum and the proximal femur. Most attempts to classify the severity of the abnormality are based on the radiographic findings. The most commonly used system is that of Aitken. This classification scheme is based upon the presence and location of the femoral head and neck on conventional radiography and provides an assessment of future limb function and plan treatment. Since this scheme however relies on conventional radiography for classification, it is difficult to classify a child until skeletal maturity which is often delayed in children with PFFD. Nevertheless, the earlier patients can be treated, the earlier normal growth can start. This case report illustrates the value of Magnetic Resonance Imaging (MRI) in addition to the standard radiographs, for early and more accurate assessment of the articular cartilaginous anatomy and soft tissue prior to ossification of the femoral capital epiphysis. As a consequence, the patient could be treated earlier to benefit treatment outcome.

Interpretation of radiographs in a pediatric limb deformity practice: do radiologists contribute?

Orthopaedic surgeons make treatment decisions based on their interpretation of patient radiographs. Radiologists' reports of these radiographs are routine but may add little to the patient's management. The authors prospectively compared data initially recorded by a pediatric orthopaedist in the assessment of teleoroentgenograms obtained over a 3-month period in a limb deformity clinic with the subsequent reports of these studies by pediatric radiologists. Two hundred and sixty-four (100%) anatomic axes of femora and tibiae were measured and reported by the surgeon compared to 1.9% by the radiologist. Limb lengths were recorded 100% of the time by the orthopaedist and by the radiologist in 80% of cases. Abnormal bone quality was present in 43 of 264 (16.2%) limb segments and reported in all involved cases by the orthopaedist. Only 26 (9.8%) of the abnormalities were noted by the radiologist. Only eight of 20 (35%) physeal abnormalities such as rickets were noted by the radiologist in contrast to 20 of 20 (100%) noted by the surgeon. There were no findings described by the radiologist not previously reported by the orthopaedic surgeon. In no case did the radiology interpretation influence clinical management decisions.

Evaluation of CT scans and 3-D reformatted images for quantitative assessment of the hip.

Hip measurements using three-dimensional (3-D) images and computed tomography (CT) scans were evaluated. The 3-D measurements proved more accurate than CT measurements of femoral and acetabular anteversion. Additionally, accurate 3-D measurements (> 99%) of the femoral neck-shaft angle were provided. Acetabular anteversion determinations by CT scans were systematically decreased as pelvic flexion increased, whereas accuracy was > 96% with 3-D images. The 3-D software allows image rotation in all three reference planes, which minimizes positional errors. A case study is provided to exemplify the shortcomings of conventional imaging techniques and the utility of the quantitative 3-D protocol.

Anormalidades congénitas del fémur / Congenital absence of the radius

Los pacientes con anormalilades congénitas del fémur presentan múltiples problemas que difícilmente son vistos por un cirujano ortopedista en forma individual. En este estudio se analizan el tratamiento de 62 anomalías congénitas del fémur en 60 pacientes, tratados en el Hospital Shriner para Niños Lisiados, de la Ciudad de México, en el periodo comprendido entre enero de 1982 y diciembre de 1991. Para todos los pacientes se utilizó la clasificación de Pappas. Los pacientes de la clase I a la VI se identifican al nacimiento, y todos requieren de tratamiento protésico. Los pacientes de las clases VII a la IX se deben evaluar en forma individual y decidir cuáles son candidatos para igualar la longitud de las extremidades. Independientemente de la clasificación se debe individualizar el tratamiento; esto depende de las malformaciones asociadas en la extremidad pélvica (hemimelia paraxial longitudinal, hipoplasia tibial y/o peronea, etc.)

The care of the limb deficient child in Venezuela.

An overview of the situation in Venezuela is made by sampling the cases of congenital limb deficiency treated at the Hospital San Juan de Dios in Caracas from 1961-1989. The major longitudinal deficiencies are analysed. The socioeconomic situation of the patients is of most importance being the cause of final decisions in relation to surgery, the ordering of prosthesis and orthosis, supplied mainly by the Venezuelan Institute of Social Security (IVSS), the maintenance of these items and the possibility of travelling to the hospital for diagnosis, treatment and follow-up. All these transform the situation from a medical problem into a socio-economic problem typical of a third world country.