Calcaneal apophysitis: a quantitative radiographic evaluation of the secondary ossification center

BACKGROUND: Calcaneal apophysitis in children is a self-limited condition that may interfere with walking and physical performance in sports, thus causing concern to the patient and parents. There is still controversy about the significance of the radiographic changes in children with heel pain, since the report of Sever in 1912. One of the reasons is that normal children may display a considerable variation in the radiographic aspects of the secondary ossification center of the calcaneus at different ages. METHODS: In this investigation, the developmental aspects of primary and secondary ossification centers of the calcaneus were studied in radiographs obtained from healthy boys and from boys with calcaneal apophysitis. The normal population comprised 392 children and adolescents ranging in age from 6 to 15 years. There were 69 individuals with calcaneal apophysitis ranging in age from 8 to 14 years. Lateral standard radiographs were obtained of both heels, and a copper step wedge was used as a calibration to determine bone density. The following parameters were analyzed on the plain films: time of appearance, fusion and number of fragments of the secondary nucleus, area and bone densitometry of the primary and secondary ossification centers of the calcaneus. RESULTS: In the normal population, the ossification of the secondary nucleus began at 7 years of age, and at 15 years of age, the nucleus was fused in all individuals. In the apophysitis group, the secondary ossification center was present and not fused in all individuals. Both secondary nuclei increased in size with age with no difference between the two groups. Regarding bone density, both the primary and secondary nuclei were less dense in the apophysitis group than their counterparts in the normal population. The most significant difference between the two populations referred to the degree of fragmentation, which was greater in the apophysitis group. CONCLUSION: Our data showed that the sclerotic aspect of the secondary nucleus of the calcaneus is a normal feature and, therefore, should not be used to establish the diagnosis of Sever's disease. The most consistent difference between the normal and apophysitis group was related to the more fragmented aspect of the secondary nucleus in the latter individuals, which may suggest a mechanical etiology for that condition.     

Calcaneal apophyseal avulsion fracture

Isolated fracture of the calcaneal apophysis is a rare injury in children and adolescents. In this study, we report on a case of a displaced calcaneal apophyseal avulsion fracture in a child treated with open reduction and internal fixation, as well as a review of the literature. A 9-year-old female child presented to the senior surgeon complaining of acute heel pain after a gymnastic injury. She was diagnosed with a displaced, isolated fracture of the proximal calcaneal apophysis for which she underwent open reduction and internal fixation. On the magnetic resonance imaging (MRI) examination, we could diagnose that her injury was not chronic but acute because there was no change of intensity in the metaphyseal area. A combination of bioabsorbable suture tacks and pins was used to anatomically fix the fragment using the tension band wiring technique. At 2 years and 6 months follow-up, she had full range of motion, complete return of strength. We report here on the successful surgical treatment and the first case evaluated by MRI of an avulsion fracture of the calcaneal apophysis in a child.     

Partial Apophysectomy in Sever's Disease

Sever's disease is an apophysitis or osteochondrosis of the calcaneal apophysis. Clinically, it includes painful heels and limitation of movement; and radiologically, fissuring and fragmentation of the calcaneal apophysis. Treatment is usually conservative, but when migration of the apophysis occurs, either posterior or plantar, surgical treatment is sometimes indicated. J Orthop Sports Phys Ther 1989;10(9):370-373.     

Conditions of the calcaneus in skeletally immature patients

Most conditions of the calcaneus in children, including calcaneal apophysitis, calcaneal fractures, and even intra-articular displaced fractures can be treated successfully with nonoperative methods. Calcaneal bone cysts require surgery only if symptomatic or at risk for pathologic fracture. Calcaneal osteomyelitis must be recognized and treated promptly to prevent severe complications.     

Autogenous transplantation of apophyseal cartilage to osteochondral defects of joints.

35S was administered to 20 puppies which had been exposed to transplantation of osteochondral apophyseal transplants from the iliac crest to defects of the femoral condyles. Some transplants were implanted into defects within the joint surfaces whereas others were implanted outside the joint surfaces. An autoradiographic study was performed to assess the functional vitality of the transplanted cartilage at varying intervals up to 14 months. This study further necessitated an investigation of the normal pattern of incorporation of 35S in the iliac crest. The studies revealed that the incorporation of 35S within the apophysis of the iliac crest was similar to that seen within pressure epiphyses, being heaviest in the proliferating and hypertrophying cells in the growth plate and around the secondary centre of ossification. The increased turnover of sulphur around the secondary centre of ossification declined, however, when the initial stage of the ossification was passed and when hypertrophy of cartilage cells was no longer seen. Ossification then took place without intensified production of organic sulphur-containing compounds in this region. The study further showed that apophyseal cartilage was still able to incorporate 35S following transplantation to the mentioned defects, except in some basal central areas adjacent to the metaphyseal bone. These findings suggested that the cartilage not only survived, but also preserved its capacity for synthetizing sulphur-containing compounds, probably chondroitin sulphate.     

Lower trabecular volumetric BMD at metaphyseal regions of weight‐bearing bones is associated with prior fracture in young girls

Understanding the etiology of skeletal fragility during growth is critical for the development of treatments and prevention strategies aimed at reducing the burden of childhood fractures. Thus we evaluated the relationship between prior fracture and bone parameters in young girls. Data from 465 girls aged 8 to 13 years from the Jump‐In: Building Better Bones study were analyzed. Bone parameters were assessed at metaphyseal and diaphyseal sites of the nondominant femur and tibia using peripheral quantitative computed tomography (pQCT). Dual‐energy X‐ray absorptiometry (DXA) was used to assess femur, tibia, lumbar spine, and total body less head bone mineral content. Binary logistic regression was used to evaluate the relationship between prior fracture and bone parameters, controlling for maturity, body mass, leg length, ethnicity, and physical activity. Associations between prior fracture and all DXA and pQCT bone parameters at diaphyseal sites were nonsignificant. In contrast, lower trabecular volumetric BMD (vBMD) at distal metaphyseal sites of the femur and tibia was significantly associated with prior fracture. After adjustment for covariates, every SD decrease in trabecular vBMD at metaphyseal sites of the distal femur and tibia was associated with 1.4 (1.1–1.9) and 1.3 (1.0–1.7) times higher fracture prevalence, respectively. Prior fracture was not associated with metaphyseal bone size (ie, periosteal circumference). In conclusion, fractures in girls are associated with lower trabecular vBMD, but not bone size, at metaphyseal sites of the femur and tibia. Lower trabecular vBMD at metaphyseal sites of long bones may be an early marker of skeletal fragility in girls. © 2011 American Society for Bone and Mineral Research.     

Metaphyseal fracture healing follows similar biomechanical rules as diaphyseal healing

It is generally supposed that the pattern of fracture healing in trabecular metaphyseal bone differs from that of diaphyseal fractures. However, few experimental studies to date have been performed, even though clinically many fractures occur in metaphyseal bone. Particularly, the influence of biomechanical factors has not yet been investigated under standardized conditions. Our aim was to correlate the interfragmentary strain (IFS) with the bone‐healing outcome in a controlled metaphyseal fracture model in sheep. Twelve sheep received a partial osteotomy in the distal femoral condyle close to the trochlea. The determination of the IFS by in vivo X‐ray analyses and a finite element model revealed that the deflection of the osteotomy gap by the patello‐femoral force during walking provoked increasing strains of up to 40%. Bone healing was evaluated after 8 weeks by the assessment of the bone mineral density and by histomorphometry in regions of interest that displayed differing magnitudes of IFS. In areas with strains below 5% significantly less bone formation occurred compared to areas with higher strains (6–20%). For strains larger than 20% fibrocartilage layers were observed. Low IFS (<5%) led to intramembranous bone formation, whereas higher strains additionally provoked endochondral ossification or fibrocartilage formation. It is therefore proposed that metaphyseal bone healing follows similar biomechanical principles as diaphyseal healing. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:425–432, 2011     

Anatomy of the os trigonum

Three anatomic specimens of os trigonum from skeletally immature patients demonstrated anatomic continuity of the cartilage containing the ossicle with the body of the talus, with a synchondrosis being present between the two ossifying regions. The os trigonum may be considered a developmental analogue of a secondary ossification center similar to the posterior calcaneal apophysis (although there are obvious histologic differences). The chondro-osseous border of the synchondrosis may be injured either as a chronic stress fracture or, less frequently, as an acute fracture, comparable to the injury patterns involving the accessory navicular.     

Calcaneal apophyseal fractures in young athletes: two case reports

Calcaneal apophyseal fracture is especially rare in young children. Furthermore, this type of fracture is sometimes overlooked in children because of subtle radiographic findings. The studies reported on this fracture are rare. We report two calcaneal apophyseal fractures that were present in the proximal half of calcaneal apophysis and were treated with fixation of the avulsed bony fragment using nonabsorbable suture.     

Histological and radiographic evaluation of three common tendon transfer techniques in an un-ossified bone porcine model: implications for early anterior tibialis tendon transfers in children with clubfeet

PurposeTo compare the histological healing and radiographic effects of tendons transferred to ossified or unossified bone using different tendon fixation techniquesMethodsNine new-born piglets underwent bilateral tendon transfers to either the ossified boney calcaneal body or unossified apophysis. The tendons were fixed using metallic suture anchors, sutures alone or a bone tunnel. At six weeks of age, calcanei were harvested, radiologically imaged and then prepared for histology. A semi-quantitative aggregated scoring system with values ranging from 0 (poor) to 15 (excellent), was used to grade healing at the surgical enthesis and the apophyseal ossification was graded by five independent reviewers in triplicate using a modified (1 to 4) validated scoring system.ResultsHistologically, the cartilaginous transfers utilizing the tunnel and suture techniques also demonstrated the best average aggregated scores of entheses healing rivalling that measured in transfers using the classic bone tunnel technique (clinical benchmark), whereas suture anchor fixation demonstrated the worst healing in both the ossified and unossified samples. All three transfer techniques caused at least minor alterations in apophyseal ossification, with the most significant changes observed in the metallic suture anchor cohort. The tunnel and suture techniques demonstrated similar and more mild abnormalities in ossification.ConclusionTendon transfers to unossified bone heal histologically as well as transfers classically performed through tunnels in bone. Suture fixation or tunnel techniques appear radiographically and histologically superior to suture anchors in our newborn porcine model.Level of evidence      

Internal architecture of the calcaneus: implications for calcaneus fractures

STUDY DESIGN: Fourteen cadaveri specimens were sectioned to analyze the internal architecture of the human calcaneus. We described the arrangement and orientation of trabecular patterns within the calcaneus and made multiple measurements of its cortical thickness. OBJECTIVE: To characterize the internal architecture of the calcaneus and correlate these findings with well-described patterns of calcaneus fracture in order to better understand the fracture mechanics of this common fracture. METHODS: Fourteen dry, frozen, human calcanei were sectioned using a saw. In each the coronal, sagittal and axial planes, we sectioned separate specimens into slices of 0.5 mm thickness. High-resolution radiographic images were taken of the sectioned specimens. The internal trabecular arrays were described and measurements of cortical thickness were recorded. The correlation between these findings and the known pattern of calcaneal fractures was analyzed. RESULTS: A dominant trabecular pattern running antero-posteriorly along the long axis of the calcaneus was observed. In the posterior tuberosity the trabeculae were arranged parallel to the posterior border. There was an area of sparse or absent mineralization in the anterior part of the calcaneus corresponding to the "neutral triangle" described by Wood and Harty 10, 23. The thickest sites of the calcaneal cortex were the lower pole of the posterior tuberosity, the upper surface at the angle of Gissane, and the lateral surface below the anterior portion of the posterior facet. CONCLUSION: The trabecular architecture of the calcaneus is created by applied stress in concordance with Wolff's law. The weakest plane of resistance to stress is parallel to these organized trabeculae or through areas lacking trabeculae. This study demonstrates that the primary and secondary fracture lines commonly encountered in calcaneus fractures correlates with the internal architectural map of the calcaneal trabecular patterns.     

A review of the recent advances in magnetic resonance imaging in the assessment of osteoporosis

Osteoporosis is a common metabolic disorder with considerable associated morbidity and mortality. The loss of bone mineral integrity and the resultant occurrence of atraumatic fractures are typically symptomatic of the disease. Currently skeletal status is commonly assessed using non-invasive conventional radiography and scintigraphy as well as densitometric techniques such as quantitative computed tomography and dual-energy X-ray absorptiometry. But, apart from gross bone mineral density, the fine structure of trabecular bone also plays an important role in defining the biomechanical competence of the skeleton. Recently attention has been focused on deriving measures that provide information about not only trabecular bone density but also microstructure. Magnetic resonance imaging (MRI) is one such new technique which potentially may provide information pertaining to bone density and structure as well as to occult fracture detection. Cortical bone produces a signal void in MR images, due to the fact that it contains very few mobile protons that give rise to a signal in MRI; also the MR relaxation time T2 of these protons is very short which produces a very fast decay of the MR signal during image acquisition. However, the trabecular bone network affects the MR properties of bone marrow. The difference in the magnetic properties of trabecular bone and bone marrow generates local imperfections in the magnetic field. The MR signal from bone marrow is modified due to these imperfections and the MR relaxation time T2* of marrow is shortened. The extent of relaxation time shortening and hence loss of signal intensity is proportional to the density of trabecular bone and marrow interfaces and their spatial architecture. Recent investigation in this area include studies aimed at quantifying marrow relaxation times and establishing their relationship to trabecular bone density and structure. In addition, with advances in imaging software and hardware, MR images at in-plane resolutions of 78–200 µm may be obtained. The trabecular bone structure is clearly revealed in such images and studies aimed at the development of high-resolution MRI techniques combined with quantitative image analysis techniques are currently under way. These potentially useful techniques for assessing osteoporosis and predicting fracture risk are reviewed in this paper.     

Quantitative magnetic resonance imaging in the calcaneus and femur of women with varying degrees of osteopenia and vertebral deformity status.

Quantitative magnetic resonance imaging (QMRI) allows measurement of two parameters that are related to the integrity of the trabecular bone: R2*, the rate constant of the free induction signal, and trabecular bone volume fraction (BVF), the counterpart of apparent density. In this work, R2* and BVF were measured in 68 women (mean age, 58.2 +/- 9.5 years) of varying spinal bone mineral density (BMD) T scores (mean, -1.37 +/- 1.54) and vertebral fracture status on a commercial 1.5 T whole-body imager using customized image acquisition and processing techniques. Twenty-five of the patients had vertebral fractures, characterized by the total cumulative deformity burden exceeding 200%. R2* was measured in the calcaneus and proximal femur and BVF could be measured in the calcaneus only. On a pixel-by-pixel basis, calcaneal R2* and BVF within each subject were highly positively correlated (r2 = 0.61 +/- 0.11) but the correlation of region-of-interest (ROI) means for different calcaneal sites among patients was weaker (r2 = 0.34; p < 0.0001). The strongest discriminator of vertebral deformity was R2* of the calcaneus, which was lower in the fracture group, consistent with lower trabecular density. Among the calcaneal sites examined, the subtalar region, a location characterized by dense nearly horizontal trabeculae that transmit the stresses imparted by body weight from the tibia to the heel, best discriminated the two groups (p = 0.0001), with 77% diagnostic accuracy as determined from the area under the receiver operating characteristic (ROC) curve (compared with 66% for vertebral BMD). The cavum calcanei, an anterior site of low trabecular density, and the tuber calcanei (the location ordinarily used for ultrasound measurements) also had significantly reduced R2* in the fracture group (p < 0.005 and p = 0.01, respectively). The R2av*, computed as the average of all pixels in the calcaneus, was a strong discriminator as well (p < 0.005). On the other hand, calcaneal BVF was only marginally discriminating (p = 0.05). Among the BMD sites examined, the lumbar spine (average L1-L4) was significant (p = 0.005, 66% diagnostic accuracy), as was the femoral neck (p = 0.01). The data suggest the calcaneus to be suited as a surrogate site to assess vertebral osteoporosis and that R2* is sensitive to alterations in bone quality not captured by density.     

A novel mouse model to study fracture healing of the proximal femur

The majority of fractures, especially in elderly and osteoporotic patients, occurs in metaphyseal bone. However, only a few experimental models exist to study metaphyseal bone healing in mice. Currently used mouse models of metaphyseal fracture healing are either based on drill hole defects, lacking adequate biomechanical stimulation at the site of fracture and therefore endochondral ossification in the fracture callus, or are introduced into the distal part of the mouse femur stabilized by a locking plate, which is challenging due to the small specimen size. Therefore, the aim of the current study was to develop a new mouse model to study metaphyseal fracture healing of the proximal femur. We chose a combination between an open osteotomy and a closed intramedullary stabilization. A 24 G needle was inserted into the femur in a closed manner, then an osteotomy was made with a 0.4-mm Gigli wire saw between the third and the lesser trochanter of the femur using an open approach. Fractured femurs were analyzed using microcomputed tomography and histology at days 14 and 21 after surgery. No animals were lost due to surgery or anesthesia. All animals displayed normal limb loading and a physiological gait pattern within the first three days after fracture. We found robust endochondral ossification during the fracture healing process with high expression of late chondrocyte and early osteogenic markers at day 14 (d14). By day 21 (d21), all fractures had a bony bridging score of 3 or more, indicating successful healing. Callus volume significantly decreased from d14 to d21, whereas high numbers of osteoclasts appeared at the fracture callus until d21, indicating that callus remodeling had already started at d21. In conclusion, we successfully developed a novel mouse model to study endochondral fracture healing of the proximal femur. This model might be useful for future studies using transgenic animals to unravel molecular mechanisms of osteoporotic metaphyseal fracture healing.     

Differential diagnosis of osteomyelitis of the calcaneus

The authers avalyse 6 cases of calcaneal osteomyelitis with rather chronic development. They present radiological and clinical differential diagnostic problems. Osteomyelitis was to seperate from Sever's disease, benign and malignant bone tumours. In 3 cases only histology or bacteriology allowed the proper diagnosis.     

Gelenknahe Fraktur

Juxta-articular fractures by definition involve the metaphyseal bone. Depending on the age of the child and the direction of displacement, there is a good potential for spontaneous correction due to the proximity to the growth plate; therefore, many of these fractures do not need an implant and can be conservatively treated. On the other hand, there may be damage to the growth plate with subsequent growth arrest. These aspects have to be considered when choosing the optimal fixation method. On the one hand stable fracture fixation is required but on the other hand the growth plate should not be significantly damaged. The most commonly used method is Kirschner wire osteosynthesis. Compression screw fixation can be an alternative in Salter and Harris type II fractures with an adequately large metaphyseal fragment. Screw fixation is also used in displaced metaphyseal avulsions or apophyseal fractures. With respect to the method of stabilization, the transition between the diaphyseal and metaphyseal regions poses a special challenge. Usually pin fixation does not lead to sufficient stability. Also elastic stable intramedullary nailing is not considered to be well suited for fractures in this region. Alternatives can be external fixator or plate osteosynthesis.     

Calcaneal Apophyseal Fracture Followed by Subtalar Joint Instability in a Young Female: A Case Report

Calcaneal apophyseal fractures are usually considered sport-related injuries. Previous repetitive microtrauma has been proposed as a predisposing factor for such injuries. However, unlike previously reported cases, in our patient, the fracture resulted from acute trauma after stepping on uneven ground. Although the first treatment option for such cases is closed reduction, most cases will require surgical treatment. Furthermore, lesions accompanying this injury have not been sufficiently considered. We report the case of a 9-year-old female with a calcaneal apophyseal fracture treated by fixation of the avulsed proximal part of the apophysis using Kirschner wires and a cerclage wire. However, subsequently, instability developed in the subtalar joint. Fifteen months after the first osteosynthesis, surgery was performed to fixate the subtalar joint and secure the insertion region of the tendo calcaneus. After the first surgery, subtalar joint instability might have developed because of simultaneous disruption of the subtalar ligaments at the initial injury. Subsequently, the instability could have caused failure of the first fixation. Debridement and fixation of the subtalar joint in the second surgery provided a stable subtalar joint. A calcaneal apophyseal fracture might be associated with additional injuries at the hindfoot. Before treating these cases, other injuries that might be obscured by the more apparent injuries should be considered. Accompanying soft tissue injuries, such as subtalar joint ligament lesions, can be revealed with magnetic resonance imaging evaluation. To the best of our knowledge, this is the first report of an apophyseal fracture of the calcaneus followed by subtalar joint instability.     

Three-Dimensional Analysis of a Ballet Dancer with Ischial Tuberosity Apophysitis. A Case Study

The purpose of this case study was to describe the three-dimensional biomechanics of common ballet exercises in a ballet dancer with ischial tuberosity apophysitis. This was achieved by comparing kinematics between the symptomatic (i.e. ischial apophyseal symptoms) and contralateral lower limbs, as well as via reported pain. Results suggest consistent differences in movement patterns in this dancer. These differences included: 1) decreased external rotation of contralateral hip, hence a decreased hip contribution to ‘turn out’; 2) increased contralateral knee adduction and internal rotation; 3) an apparent synchronicity in the contralateral lower limb of the decreased hip external rotation and increased knee adduction; and 4) minimal use of ankle plantar/dorsiflexion movement for symptomatic side. Pain related to the left ischial apophysitis was associated with reduced amplitudes especially in fast ballet movements that required large range of motion in flexion and adduction in the left hip joint. These findings suggest that ischial apophysitis may limit dancer’s ballet technique and performance.

Key Points

• The pain related to the left ischial apophysitis was associated with reduced amplitudes especially in fast ballet movements that require large range of motion. This may affect to the lower limbs kinematics, and limit dancer’s technique and performance.
• Compensatory strategies in the kinetic chain, differences in the joint angles between the lower limbs, traction forces, velocity and amplitude demands should be taken in consideration while training and rehabilitation of the ischial apophyseal injury within classical ballet.

Key words: Sports injuries, dance, case study, biomechanics     

Genetic variations that regulate bone morphology in the male mouse skeleton do not define its susceptibility to mechanical unloading

Genetics can substantially influence bone morphology and may define the skeleton's response to mechanical unloading. Recent data indicated that disuse produces different site-specific responses in the skeleton of genetically distinct adult female C3H/HeJ (C3H) and BALB/cByJ (BALB) mice; while disuse BALB mice had significantly less bone than age-matched controls in the distal and diaphyseal femur, the removal of weight bearing had a much smaller influence in C3H. Using adult male mice from these two inbred strains, the hypothesis was tested that interactions between genetic variations and anatomic location define bone morphology and its susceptibility to unloading. Four-month-old male BALB and C3H mice were either subjected to 21 days of hindlimb unloading or served as controls. Multiple cortical and trabecular regions within the distal and diaphyseal femur were analyzed by micro-computed tomography. C3H controls had significantly greater diaphyseal and metaphyseal cortical bone area (45% and 32%) and greater metaphyseal trabecular bone volume fraction (67%) than BALB controls, but epiphyseal trabecular bone volume fraction was similar between the two strains. Despite these substantial, site-specific differences in bone morphology, disuse induced similar changes in bone morphology in these two strains. Compared to controls, disuse BALB and C3H had significantly less metaphyseal (17% and 19%) and epiphyseal (10% and 13%) trabecular bone, while diaphyseal and metaphyseal cortical bone geometry was unaffected. These data indicate that the genetic variations that caused spatially nonuniform differences in trabecular and cortical bone morphology between the two strains had little influence on the susceptibility of a specific site to unloading. Cross-gender comparisons with previous data from female BALB and C3H mice further suggest strong interactions by which gender, genotype, and anatomical location define the response of the skeleton to the removal of weight bearing.