Muscle forces acting on the greater trochanter lead to a dorsal warping of the apophyseal growth plate.

The apophyseal growth plate of the greater trochanter, unlike most other growth plates of the human body, exhibits a curved morphology that results in a divergent pattern resembling an open crocodile mouth on plain antero-posterior radiographs. To quantify the angular alignment of the growth plate and to draw conclusions about the function of the muscles surrounding it, we analyzed 57 MRI images of 51 children and adolescents aged 3-17 years and of six adults aged 18-52 years. We measured the angulation of the plate relative to the horizontal plane (AY angle) and the trajectories of the muscles attaching to the greater trochanter of the proximal femur. From anterior to posterior, the AY angle shows a decrease of 33.44°. In the anterior third, the cartilage is angled at a mean of 51.64°, and in the posterior third, the mean angulation is 18.6°. This indicates that the cartilage in the anterior region of the greater trochanteric apophysis is subject to more vertically oriented force vectors compared to the posterior region, as the growth plates align perpendicular to the force vectors acting on them. Combining the measured muscle trajectories with the physiological cross-sectional areas (PCSA) available from the literature revealed that, in addition to the known internal and external lateral traction ligament systems, a third, dorsally located traction ligament system exists that may be responsible for the dorsal deformation of the AY angle.

Functional adaptation after femoral intertrochanteric valgus osteotomy in Legg-Calvé-Perthes disease.

Legg-Calvé-Perthes disease (LCPD) requires individualized treatment in order to regain a functional hip joint. In severe cases, in which a congruent joint cannot be achieved, other options are necessary in order to improve functionality and prevent early osteoarthritis. Therefore, we analysed the clinical and radiologic outcome of 28 patients after valgus osteotomy of the proximal femur (VOF). We examined the range of hip motion, functionality and health-related quality of life (HRQoL) via modified Harris Hip Score (mHHS) and Kidscreen-10. Radiographic analysis contained quantitative and qualitative measurements of hip morphology. In particular, we correlated the results with the change of the pelvic-femoral angle (PFA). PFA was defined as the angle between the anatomical diaphyseal line of the femur and a vertical line through the pelvis. The mean follow-up was 5.5 years. Patients showed high mHHS and good HRQoL postoperatively. An increase in ROM with an improvement of 30.5° abduction and 10.3° internal rotation was evident. PFA correlated with adduction contracture and improved significantly after surgery. In consideration of careful patient selection, VOF showed a positive effect on ROM, pain, HRQoL, radiographic congruence and outcome. We identified the age at surgery and an increasing adduction contracture-objectified by a decreased PFA-as a prognostic factor.

[Clinical aspects of imaging the hip in infants, children and adolescents]. / Klinische Aspekte zur Bildgebung der kindlichen und adoleszenten Hüfte.

When a child with a hip problem is clinically evaluated, it is usually possible to make a presumptive diagnosis which is subsequently confirmed. The most important tool for confirmation in pediatric hip disorders is radiological imaging. Vice versa changes on sonogram, native X­ray or magnetic resonance images (MRI) can often only be interpreted when the history and current clinical findings are known. In this constellation, it is desirable that all colleagues who are confronted with a child's hip problem know the most common and important pediatric hip disorders and use the same terminology. The aim of this article is to present a short outline of the pathogenesis and clinical aspects of congenital and neurogenic hip dysplasia, coxitis fugax, septic coxitis, Perthes' disease, infantile and adolescent femoroacetabular impingement, apophysiolyses, and slipped capital femoral epiphysis.

[Lumbo-pelvino-acetabular alignment-basics and clinical consequences]. / Lumbo-pelvino-azetabuläres Alignment ­ Grundlagen und klinische Konsequenzen.

The spinal shape and the pelvic ante-/retroversion of an individual are determined by its innate, genetically fixed lumbosacral angulation. This can be measured with little effort in the lateral standing radiograph of the patient. In spinal surgery, there are a lot of original papers on the topic. In hip surgery, however, the individual pelvic version and its consequences for the acetabular orientation have not received the same attention so far.This review focuses on previous data on the relationship between lumbosacral angulation and pelvic ante-/retroversion. Four anatomically definable pelvic types can be distinguished; three of those have to be considered as facultatively pathogenetic. Clinical consequences arise for the clinical pictures of spondylolisthesis, non-specific lower back pain, acetabular retroversion and developmental dysplasia of the hip, as well as for acetabular cup positioning in total hip arthroplasty.

Clinical examination and patients' history are not suitable for neonatal hip screening.

Purpose: To assess the percentage of missed developmental dysplasia of the hip, which escape the German criteria for newborn hip high-risk screening, we analyzed our data gained from the general neonatal sonographic hip screening performed at our department. The aim of the study was to determine the number of potentially belatedly treated developmental dysplasia of the hip. Methods: The data from 1145 standardized newborn hip ultrasound examinations according to the Graf technique were analyzed retrospectively comparing findings for general neonatal sonographic hip screening and high-risk screening subgroups. Results: We diagnosed developmental dysplasia of the hip in 18 of the 1145 newborns via ultrasound. A total of 10 out of 18 developmental dysplasia of the hip would have been missed by high-risk screening, which corresponds to a proportion of 55.6% false-negative results. The sensitivity of high-risk screening was only 44.4% and specificity, 78.3%. The positive predictive value was 3.2%. Family history as a screening criterion yielded false-negative results in 77.8% and false-positive results in 16.8%. In all, 83.3% of the children who were born with developmental dysplasia of the hip but not from breech position as a risk factor were false negative. The clinical examination was false negative in 88.9% and false positive in 0.6%. Conclusion: High-risk screening detected less than every second developmental dysplasia of the hip, rendering the first month as the most effective treatment window unavailable for inapparent dysplastic hips, potentially resulting in the need for more invasive treatment. Due to the high sensitivity of ultrasound in the detection of developmental dysplasia of the hip, we recommend to replace the current German high-risk screening guidelines with a general newborn screening for all neonates using Graf ultrasound in the first week of life. Level of evidence: Level II.

Physiologic and Pathologic Development of the Infantile and Adolescent Hip Joint: Descriptive and Functional Aspects.

The basic law of mechanobiology states that the external form and internal architecture of the skeleton and joints follow the functional stimuli that act upon them. Radiographs and magnetic resonance imaging reflect the loading history of the growing child, enabling an experienced radiologist to analyze the clinical functioning of patients by interpreting imaging studies. Concerning the hip joint, the physes of the coxal femoral end, the coxal femoral epiphysis with its epiphyseal growth plate, as well as the apophysis of the greater trochanter with its trochanteric growth plate, are the essential organ structures subject to internal forces. They determine the definitive geometric shape of the proximal femur. Indirectly they influence the appearance of the acetabulum and the centration of the hip joint.

Can Salter osteotomy correct late diagnosed hip dysplasia: A retrospective evaluation of 49 hips after 6.7 years?

BACKGROUND: Surgical treatment of late diagnosed development dysplasia of the hip (DDH) remains challenging with several methods being described. We therefore retrospectively evaluated the outcome of Salter innominate osteotomy (SIO) in patients with fully-grown bone, to evaluate whether this surgical procedure allows sufficient acetabular correction. MATERIAL AND METHODS: Between 2004-2012 SIO had been performed in 45 patients (49 hips) with late diagnosed DDH. The evaluation included pre- and postoperative radiographs (n=49), the complication rate (n=49) and the clinical outcome (WOMAC, HHS, UCLA) (n=34). RESULTS: Mean age at surgery was 27.6 (16-51) with a follow-up of 6.7±2.7 (0.9-11.0) years. Radiologically, a good acetabular correction with a significant improvement of the Center Edge angle (15.4° to 34.9°), sharps angle (45.7° to 32.0°) and migration percentage (33.2% to 14.4%) (p<0.001) was found. Clinical results revealed a WOMAC of 13.9±13.3, UCLA of 7.8±2.1 and HHS of 85.0±11.8. Complications were noted for 10 patients (20%) with 7 (14%) requiring revision. CONCLUSION: The results demonstrated that SIO achieved a satisfying acetabular correction and good clinical results in late diagnosed DDH. It therefore might be an option in some cases, although periacetabular osteotomy techniques are currently preferable used as they allow a wider range of acetabular correction. LEVEL OF EVIDENCE: IV, retrospective observational study.

Normal radiological unossified hip joint space and femoral head size development during growth in 675 children and adolescents.

Evaluation of hip joint space width during child growth is important to aid in the early diagnosis of hip pathology in children. We established reference values for hip joint space and femoral head size for each age. Hip joint space development during growth was retrospectively investigated medial and cranial in 1350 hip joints of children using standard anteroposterior supine plain pelvic radiographs. Maximum capital femoral epiphysis diameter and femoral radii were further more investigated. Hip joint space values show a slow decline during growth. Joint space was statistically significantly (p < 0.006) larger in boys than girls. Our hip joint space measurements on supine subjects seem slightly larger than those reported by Hughes on standing subjects. Evaluation of the femoral head diameter and the radii showed a size curve quite parallel to the known body growth charts. Radii medial and perpendicular to the physis are not statistically significantly different. We recommend to compare measurements of hip joint space at two locations to age dependent charts using the same imaging technique. During growth, a divergence in femoral head size from the expected values or loss of the spherical shape should raise the question of hip disorder. Clin. Anat. 30:267-275, 2017. © 2016 Wiley Periodicals, Inc.

Discrepancy between sonographic and radiographic values after ultrasound-monitored treatment of developmental dysplasia of the hip.

INTRODUCTION: The purpose of the study was to examine the accordance between the actually used sonographic and radiographic standard values after ultrasound-monitored treatment of developmental dysplasia of the hip (DDH). MATERIAL AND METHODS: One hundred and fifty-three (119 children) ultrasound-monitored treated hips (initial staging according to Graf: type IIc-IV) which attained normal ultrasound findings (type I according to Graf) during treatment and underwent an anteroposterior radiograph of the pelvis at the time of starting walking (mean age 18.6 months) were evaluated retrospectively. RESULTS: While all hips showed normal sonographic values (Graf type I), 26 (17%) showed mild and 17 (11.1%) severe dysplasia (by measuring the acetabular index) according to the radiographic Toennis classification system, and 29 (19%) showed mild and 48 (31.4%) severe dysplasia according to the Wiberg centre-edge angle. CONCLUSIONS: This data show that the actually used sonographic and radiographic standard values concerning DDH do not correlate appropriately. It must be put up for discussion whether the radiographic standard values might be too strict. Further criteria must be developed to better assess the prognosis of residual dysplasia.

The underused hip in ipsilaterally orthotics-dependent children.

BACKGROUND: The aim of this investigation is the development of primarily healthy hips in children who have required orthoses/protheses over the long term due to ipsilateral distally located deformities of the leg. These children show ipsilateral in-toeing gait and Duchenne's limping followed by a coxa valga antetorta and facultative hip decentration. A practical question is whether these hips are in danger of decompensation. An additional theoretical question is how the external shape and internal architecture changes if a primarily healthy hip is underused. METHODS: Ten children with healthy hips who are unilaterally long-term orthotics/prosthetics-dependent agreed to undergo an instrumental gait analysis. The results were analyzed and correlated with clinical findings, a common activity score and planimetric radiographic data. RESULTS: The intra-individual comparison revealed a number of significant changes in the hip of the deformed leg (p < 0.05). Clinically, the internal rotation was increased (15° ± 4.2°), while the external rotation was diminished (13° ± 1.3°). Radiologically, the projected caput-collum-diaphyseal angle, the lesser trochanter to articular surface distance and the head-shaft angle were increased by 11.1° ± 15.4°, 5.8 ± 4.2 mm and 11.9° ± 0.6°, respectively. Both the Sharp and acetabular angles were increased, the former by 3.6° ± 0.6° and the latter by 3.2° ± 0.6°. Kinetic gait analysis showed increased stride length (6.8 ± 3.7 cm), shortened stance phase (6.6 ± 1.6 %) and reduced forces transmitted to the ground (92.2 ± 34.3 N). The kinematic analysis showed increased hip abduction (14.0° ± 8.2°), while the pelvic obliquity was not significantly changed (0.01° ± 0.01°). CONCLUSIONS: Duchenne's limp and lack of weight-bearing stress are the decisive pathogenic factors of the underused coxa valga and acetabular dysplasia. These changes follow the mechanobiological concept of "function modifies design", which means function influences external shape and internal architecture of bones and joints. As a practical consequence we recommend that one pelvic radiograph be performed as a precaution at the end of puberty of children with these conditions. LEVEL OF EVIDENCE: Level II retrospective study.

Midterm results after subtrochanteric end-to-side valgization osteotomy in severe infantile coxa vara.

BACKGROUND: For the treatment of the severe infantile coxa vara it is mandatory for the orthopaedic surgeon to observe the mechanobiology of the growing hip before and after the surgical intervention. We hereby would like to present our experiences with the subtrochanteric end-to-side valgization osteotomy and to compare the procedure with the alternatively used Y-shaped osteotomy as described by Pauwels. METHODS: Thirteen patients (20 hips) who had undergone subtrochanteric end-to-side valgization were followed for a mean 6.2 years (range, 0.8 to 12.8 y). At the time of surgery the mean age was 7.1 years (range, 2.0 to 13.3 y), last follow-up examination was performed at a mean of 13.4 years of age (range, 5.1 to 18.3 y). The deformities were etiologically based on 5 entities: congenital coxa vara (n=1), osteochondrodysplasias (n=12), postosteomyelitic coxa vara (n=5), and avascular femoral head necrosis in the course of congenital dysplasia of the hip (n=2). The follow-up rate was 100%.In addition, we analyzed a total of 93 pelvic radiographies with a total of 139 hip joints. Thirty angles and distances were assessed according to parameters described in the literature. RESULTS: Although preoperatively 12 patients presented with a positive Trendelenburg's sign, it was only present postoperatively in 2 patients. Duchenne's limp reduced from 10 to 1. All of the 15 preoperatively apparent nonunions could be healed by means of surgery. Two hips redeveloped pathologically lowered collodiaphyseal angles postoperatively, one of which had to undergo revision surgery. Preoperatively 15 out of 20 patients (75%) showed nonunions all of which healed after surgery. No recurrence could be seen at the time of the last follow-up.The following angles were assessed on plain radiographies of the pelvis preoperatively and directly postoperatively as well as on the last follow-up at a mean of 85 months: CCD-angle 98 degrees/156 degrees/144 degrees, EY-angle 55 degrees/5 degrees/15.7 degrees, AY-angle 32 degrees/75 degrees/66 degrees, CE-angle 20 degrees/25 degrees/18 degrees, AC-angle 20 degrees/18 degrees/20 degrees. The articulotrochanteric distance was 5 mm/26 mm/14 mm. CONCLUSIONS: The subtrochanteric end-to-side valgization osteotomy showed to be highly effective in the management of the infantile coxa vara, improving the clinical impairment of the patients postoperatively. All of the preoperatively present nonunions showed osseous consolidation at follow-up examination. Only minor revarization tendencies could be found. The procedure is technically less demanding, safer and more efficient regarding the lengthening of the affected limb in comparison to the Y-shaped intertrochanteric osteotomy as described by Pauwels. LEVEL OF EVIDENCE: Case-control study (EBM-level III).

Subject-specific finite element simulation of the human femur considering inhomogeneous material properties: a straightforward method and convergence study.

In numerical finite element (FE) simulations of human bones subject-specific models are necessary to reproduce the physiological conditions, which include the determination of inhomogeneous material properties from computed tomography (CT) scans and their implementation in the numerical model. In the present approach common software packages are directly used for the entire simulation process from segmentation of CT scans, surface reconstruction, mesh generation, calculation of mean element densities to FE simulation. The influence of the mesh discretisation level on the maximum displacement, the total system energy and the principal surface stress distribution of eight human femurs was analysed. Both the maximum displacement and the total system energy showed typical convergence behaviour towards an asymptotic value with decreasing element size. The principal surface stress distribution followed similar qualitative trends at all mesh discretisation levels studied for the same femur. However, the stress distributions did not converge with decreasing element size and still differed significantly between the two smallest element sizes studied of approximately 2mm and 1mm. The magnitude of convergence differed among the individual femurs. Thus, individual convergence studies in terms of local stress or strain distributions are necessary for accurately predicting local stress and strain values in subject-specific FE bone models.

Soft tissue release of the spastic hip by psoas-rectus transfer and adductor tenotomy for long-term functional improvement and prevention of hip dislocation.

The purpose of this study was to assess the long-term development of children with cerebral palsy treated with soft tissue releases of the hip and, if necessary, also of the hamstrings and the Achilles tendon. The follow-up had to consider the functional status and the hip centration. Seventy-one patients (46 with tetrapareses, 24 with dipareses, and one with triparesis) who underwent soft tissue releases of the hip by the so-called psoas-rectus transfer at an average age of 7 years were assessed preoperatively, after 1 year and at an average age of 19 years. Functional status and the radiological lapse were assigned. The functional status of the patients significantly improved (P<0.001) after surgery. The number of patients who were able to walk increased from 49.3 to 80.3%. The migration percentage decreased from 26.6 to 17.3%. For medium-to-severe functional deficits, a clear gain of function and a safe prevention of spastic hip luxation were achieved.

Long-term result after femoral head substitution in postinfectious aplasia of the femoral head.

PURPOSE: This case report presents a new and unique surgical greater trochanter split procedure for reconstructing a hip joint after an infantile hip sepsis with consequent aplasia of the femoral head. METHODS: One patient underwent the new trochanter split osteotomy for postinfectious aplasia of the femoral head at the age of 4 years. A follow-up of 17 years is presented. SURGICAL TECHNIQUE: The remaining proximal femur is sagittally split and the medial part is shifted into the acetabulum, preserving the lateral part of the greater trochanter. The osteotomy is fixed by an osseous wedge and K-wires. In contrast to the techniques known so far, it does not harm the vastogluteal muscle sling, thus, significantly reducing abductor lurch. Furthermore, through placing juvenile growth cartilage from the greater trochanter area into the acetabulum, there is, by far, more potential for the regeneration of a femoral head than by the procedures known so far. CONCLUSION: The presented surgical technique is able to improve the biomechanics of a hip joint with postinfectious aplasia of the femoral head. The growth of a new femoral head and the development of a well-shaped acetabulum is enabled. A clinical outcome with a stable joint and very good clinical function can be achieved.

Normal development of the hip: a geometrical analysis based on planimetric radiography.

The existing studies on the development of the hip joint predominantly focus on either the acetabulum or the proximal femur. This paper investigates the parallel geometrical development of both, the proximal femur and the acetabulum during growth. Six hundred and seventy-five hips with an age from 9 months to 16 years were studied by means of planimetric radiography; angles and lever arms were determined. Although the apophyseal angles remain virtually unchanged throughout growth, the epiphyseal angles and the neck-shaft angle undergo typical changes until the age of 10 years. Subsequently, there are no major changes in the angular conformation of the proximal femur, whereas acetabular coverage and its centric alignment continue to develop further until the end of skeletal growth. The load and muscle lever arms increase until the end of growth with their ratio remaining constant after the age of 10 years. We present correlated data on the geometrical development of the acetabulum and the proximal femur. The interpretation of our findings is to some extent limited by the two-dimensionality of planimetric radiography. Our results do, however, support the timing of corrective osteotomies of the proximal femur relatively soon after the age of 10 years.

Function-orientated structural analysis of the proximal human femur.

In his model of the biomechanics of the proximal human femur, Friedrich Pauwels assumes a resultant force acting on the femoral head that is created by the partial body weight and the force of the abductor muscles inserting at the greater trochanter. This model suggests a tensile force in the region of the greater trochanter. An exact examination of the muscle insertions at the greater trochanter resulted in a contrasting hypothesis assuming a local compression stress in the region of the greater trochanter. The aim of this study was to examine which hypothesis is favored by the internal architecture of the proximal femur. Based on the architectural software Allplan(R), we performed an extended analysis of the trabecular structure within the proximal femur using CT scans of 10 human cadaver femora altogether. According to our results, both the medial and the trochanteric trabecular systems are orientated approximately perpendicular to the arcuate trabecular system [angles between systems ranging from 84.6 to 93.0 degrees (mean angle 90.7 degrees ) and from 80.9 to 86.5 degrees , (mean angle 84.9 degrees ), respectively]; furthermore, the medial trabecular system is orientated perpendicular to the epiphysis of the femoral head (mean of angles: 94.7 degrees ). The biomechanical interpretation of these results strongly supports the idea of compressive stress in the region of the greater trochanter and makes a predominant tensile force of the abductor muscles highly unlikely.