Distal Femoral Growth Plate Research Articles

Local Changes to the Distal Femoral Growth Plate Following Injury in Mice.

Injury to the growth plate is associated with growth disturbances, most notably premature cessation of growth. The goal of this study was to identify spatial changes in the structure and composition of the growth plate in response to injury to provide a foundation for developing therapies that minimize the consequences for skeletal development. We used contrast-enhanced microcomputed tomography (CECT) and histological analyses of a murine model of growth plate injury to quantify changes in the cartilaginous and osseous tissue of the growth plate. To distinguish between local and global changes, the growth plate was divided into regions of interest near to and far from the injury site. We noted increased thickness and CECT attenuation (a measure correlated with glycosaminoglycan (GAG) content) near the injury, and increased tissue mineral density (TMD) of bone bridges within the injury site, compared to outside the injury site and contralateral growth plates. Furthermore, we noted disruption of the normal zonal organization of the physis. The height of the hypertrophic zone was increased at the injury site, and the relative height of the proliferative zone was decreased across the entire injured growth plate. These results indicate that growth plate injury leads to localized disruption of cellular activity and of endochondral ossification. These local changes in tissue structure and composition may contribute to the observed retardation in femur growth. In particular, the changes in proliferative and hypertrophic zone heights seen following injury may impact growth and could be targeted when developing therapies for growth plate injury.

Predictors of soft-tissue complications and deep infection in allograft reconstruction of the proximal tibia.

Reconstruction of the proximal tibia after wide resection of malignant tumors in the pediatric population is very challenging. Advocates of allograft reconstruction argue as advantages bone preservation, biological reconstruction that facilitates reattachment of the extensor mechanism and other soft-tissue structures, delay of metallic prosthesis use and preservation of the distal femoral growth plate. However, complications are significant, infection being very common. Under IRB-approved protocol, 32 patients (17 males, 15 females), 13 years old in average (2-20), who underwent 33 allograft reconstructions of the proximal tibia, were evaluated for the occurrence of soft-tissue complications and/or deep infection (infection affecting the allograft). Potential predictors of soft-tissue complications and deep infection, categorized as pre- and perioperative variables, were analyzed in relation to the risk for developing a soft-tissue complication or a deep infection. The prevalence of soft-tissue complications was 48% (16/33). However, we were not able to identify any significant predictors. The prevalence of deep (allograft) infection was 15% (5/33). Multivariate logistic regression determined higher BMI at the index surgical procedure and lower pre-operative WBC to be independent predictors of deep infection. For each unit of increase in BMI, the odds of deep infection increased by 40% (OR = 1.40; CI = 1.07-3.06; P < 0.05). For each one unit (1,000) of increase in the pre-operative white cell-count, the odds of deep infection decreased by 70% (OR = 0.30; 95%CI = 0.01-0.89; P < 0.05). Four of the five deep infections were in patients with soft-tissue complications, mainly wound dehiscence. However, wound dehiscence or soft-tissue complications were not predictive of deep infection. Soft-tissue complications are prevalent in allograft reconstruction of the proximal tibia. Prevention is important as these may progress to deep infection. Careful attention to nutritional (BMI) and immunological status may help in patient selection for allograft reconstruction. If allograft reconstruction is opted for, efforts should focus on optimization of these factors as they proved to be independent predictors of subsequent deep infection. J. Surg. Oncol. 2016;113:811-817. © 2016 Wiley Periodicals, Inc.

Genetically engineered flavonol enriched tomato fruit modulates chondrogenesis to increase bone length in growing animals.

Externally visible body and longitudinal bone growth is a result of proliferation of chondrocytes. In growth disorder, there is delay in the age associated increase in height. The present study evaluates the effect of extract from transgenic tomato fruit expressing AtMYB12 transcription factor on bone health including longitudinal growth. Constitutive expression of AtMYB12 in tomato led to a significantly enhanced biosynthesis of flavonoids in general and the flavonol biosynthesis in particular. Pre-pubertal ovary intact BALB/c mice received daily oral administration of vehicle and ethanolic extract of wild type (WT-TOM) and transgenic AtMYB12-tomato (MYB12-TOM) fruits for six weeks. Animal fed with MYB12-TOM showed no inflammation in hepatic tissues and normal sinusoidal Kupffer cell morphology. MYB12-TOM extract significantly increased tibial and femoral growth and subsequently improved the bone length as compared to vehicle and WT-TOM. Histomorphometry exhibited significantly wider distal femoral and proximal tibial growth plate, increased number and size of hypertrophic chondrocytes in MYB12-TOM which corroborated with micro-CT and expression of BMP-2 and COL-10, marker genes for hypertrophic cells. We conclude that metabolic reprogramming of tomato by AtMYB12 has the potential to improve longitudinal bone growth thus helping in achievement of greater peak bone mass during adolescence.

Low Risk of Physeal Damage from a Medial Patellofemoral Ligament (MPFL) Reconstruction Technique that Uses an Epiphyseal Socket in Children

Objectives:The purpose of this study was to assess short-term distal femoral growth plate safety associated with femoral sockets for hamstring autograft fixation in pediatric MPFL reconstruction.Methods:We retrospectively reviewed a consecutive series of 31 patients (22 females, 9 males) that underwent MPFL reconstruction by one surgeon at a tertiary care academic medical center between 2008 and 2014. Study inclusion criteria consisted of patients who were skeletally immature at the time of surgery, who had greater than 1 year radiographic follow-up and who had a femoral socket introduced during their procedure. Femoral socket location was verified by intraoperative fluoroscopy. All patients received a post-operative x-ray and a clinical follow-up. For the 12 patients that obtained post-operative MRI, growth plate safety was assessed by examining the location of the femoral socket relative to the physis to rule out growth plate injury (Figure 1). Development of lower limb angular deformities or limb length discrepancies was evaluated by examining post-operative standing hip-to-ankle anteroposterior radiographs, patient records, and clinical assessments.Results:The average age at surgery of 13.0 years. The average length of radiographic follow-up was 1.5 years and the average length of clinical follow-up was 1.78 years. At most recent clinical follow-up, 90% (28/31) of patients reported no subsequent patellar dislocations in the treated knee. No patients showed evidence of an angular deformity or limb length discrepancy. Of the 12 patients with postoperative MRI, all showed femoral sockets positioned distal to the physis without growth plate disturbance.Conclusion:The use of an epiphyseal femoral socket for graft fixation presents minimal risk of physeal violation and ensures patellar stability in the majority of pediatric patients. We have demonstrated that using fluoroscopic assistance to place the femoral socket distal to the distal femoral physis is a reliable and safe method for avoiding physeal injury in children with patellar instability.

Interventions for treating growth plate fractures of the distal femur: a systematic review protocol

REVIEW QUESTION/OBJECTIVE 1.What are safe and effective interventions for the management of distal femoral growth plate fractures in children in terms of rates of growth deformity and rates of growth arrest? More specifically, the objectives are to compare: 1. different methods of surgical treatments in the acute management of distal femoral growth plate fractures in children and adolescents; 2. different methods of non-surgical treatments in the acute management of distal femoral growth plate fractures in children and adolescents; 3. surgical versus non-surgical treatments in the acute management of distal femoral growth plate fractures in children and adolescents; and 4. different outpatient follow-up strategies, in particular, frequency of visits, frequency of radiographic evaluation and longevity of patient follow-up, following treatment of distal femoral growth plate fractures in children. Surgery will be defined as treatment either by incision or physical manipulation by a surgical doctor. INCLUSION CRITERIA Types of participants This review will consider studies which include male and female children, younger than or equal to 18 years of age, with a distal femoral physeal fracture treated either operatively or conservatively, within 72 hours of presentation to hospital. Children may have a single or multiple injuries. The distal femoral physeal fractures considered may be open or closed injuries. Studies which follow-up these patients in the outpatient setting will also be reviewed to evaluate the incidence or detection rates of the later-appearing complications. This review will not consider children with osteochondritis dissecans, Blount’s disease, or children with other comorbidities TRUNCATED AT 250 WORDS

The origin points of the knee collateral ligaments: an MRI study on paediatric patients during growth.

Different femoral origins for both the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) have been reported in the growing skeleton (epiphyseal and metaphyseal). Knowledge about the exact attachment sites is mandatory for anatomically correct reconstruction. This study assesses the femoral origins of the knee collateral ligaments in skeletally immature individuals using magnetic resonance imaging (MRI). MRIs of 336 knee joints (median age 15 years (range 2-18 years), m = 209 and f = 127) were retrospectively analysed to assess the distances between the femoral origins of the MCL and LCL to the distal femoral growth plate. In 175 patients, the body sizes were additionally retrieved from medical records. Both MCL and LCL ligament origins were invariably located on the epiphysis. Mean MCL origin-growth plate distance was 9.6 mm (SD 2.1 mm; range 2.2-13.6 mm) in boys and 8.6 mm (SD 1.5 mm; range 3.4-12.0 mm) in girls. Mean LCL origin-growth plate distance was 9.3 mm (SD 1.8 mm; range 4.3-13.0 mm) in boys and 8.2 mm (SD 1.5 mm; range 3.4-11.8 mm) in girls. The distance between the growth plate and both collateral ligaments as well as the length of the LCL correlated positively with patients' age and body size (MCL R(2) = 0.673 and 0.556, LCL R (2) = 0.734 and 0.645, LCL length R(2) = 0.589 and 0.741; all p < 0.001). During growth, the femoral origins of the MCL and the LCL are constantly located on the distal femoral epiphysis. There is a linear increase in the distances from the ligaments' origins to the growth plate according to age and body size. This new information may be of clinical importance for reconstructive surgery of the knee's collateral ligaments.

Ipsilateral distal femoral and proximal tibial epiphyseal growth plate injury: a case report

IntroductionBoth the isolated distal femoral epiphysiolysis and the isolated proximal tibial epiphysiolysis are the least common epiphyseal injuries. Even though they are uncommon, they have a high incidence rate of complications.Case presentationWe present a case with Gustilo-Anderson grade 3b open and Salter-Harris type 1 epiphysiolysis of the distal femur and proximal tibia caused by a farm machinery accident. The patient was a 10-year-old boy, treated by open reduction and internal fixation.ConclusionAlthough distal femoral and proximal tibial growth plate injuries are rarely seen benign fractures, their management requires meticulous care. Anatomic reduction is important, especially to minimize the risk of growth arrest and the development of degenerative arthritis. However, there is a high incidence of growth arrest and neurovascular injury with these type of fractures.

Anatomic Reconstruction of the Medial Patellofemoral Ligament in Children and Adolescents With Open Growth Plates

Background: Recurrent lateral patellar dislocation is a common knee injury in the skeletally immature adolescent. Because of the open physis, operative therapy in children is challenging. This study presents the outcomes of a minimally invasive technique for anatomic reconstruction of the medial patellofemoral ligament (MPFL) in children that respects the distal femoral physis. Hypothesis: Anatomic reconstruction of the MPFL in children that maintains the distal femoral physis will prevent redislocation, preserve the distal femoral physis, and improve knee function. Study Design: Case series; Level of evidence, 4. Methods: Twenty-one consecutive patients with patellofemoral instability and open growth plates underwent anatomic reconstruction of the MPFL that maintained the distal femoral growth plate. Preoperative radiographic examination included AP and lateral views to assess patella alta and limb alignment. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and tibial tubercle–trochlear groove (TT-TG) distance. Evaluation included preoperative and postoperative physical examination, Kujala score, and Tegner activity score. Results: The average age at the time of operation was 12.2 years (range, 10.3-13.9). The average follow-up after operation was 2.8 years after surgery (range, 2.0-3.6). No recurrent dislocation occurred, but 2 patients with high-grade trochlear dysplasia still had a positive apprehension sign. The Kujala score significantly improved from 72.9 (range, 37-87) preoperatively to 92.8 (range, 74-100) postoperatively (P < .01). The Tegner activity score decreased, but not significantly, from 6.0 (range, 3-9) preoperatively to 5.8 (range, 3-9) postoperatively (P = .48). Conclusion: Anatomic reconstruction of the MPFL that respects the distal femoral physis in skeletally immature patients is a safe and effective technique for the treatment of patellofemoral instability and allows patients to return to sports without redislocation of the patella.

Low-level laser on femoral growth plate in rats

To determine the influence of low-level laser therapy on femoral growth plate in rats. Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm(2). The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. The low-level laser therapy negatively influenced the distal femoral growth plate.

Leptin Antagonizes Peroxisome Proliferator-Activated Receptor-γSignaling in Growth Plate Chondrocytes

Leptin is an obesity-associated cytokine-like hormone encoded by the ob gene. Recent studies reveal that leptin promotes proliferation and differentiation of chondrocytes, suggesting a peripheral role of leptin in regulating growth plate function. Peroxisome proliferator-activated receptor-γ (PPARγ) is a transcriptional regulator of adipogenesis. Locally, PPARγ negatively regulates chondrogenic differentiation and terminal differentiation in the growth plate. The aim of this study was to test the hypothesis that leptin may suppress the inhibitory effects of PPARγ on growth plate chondrocytes. Chondrocytes were collected from distal femoral growth plates of newborn rats and were cultured in monolayer or cell pellets in the presence or absence of leptin and the PPARγ agonist ciglitazone. The results show that leptin attenuates the suppressive effects of PPARγ on chondrogenic differentiation and T3-mediated chondrocyte hypertrophy. Leptin treatment also leads to a mild downregulation of PPAR mRNA expression and a significant MAPK/ERK-dependent PPARγ phosphorylation at serine 112/82. Blocking MAPK/ERK function with PD98059 confirmed that leptin antagonizes PPARγ function in growth plate chondrocytes through the MAPK/ERK signaling pathway. Furthermore, leptin signaling in growth plate cells is also negatively modulated by activation of PPARγ, implying that these two signaling pathways are mutually regulated in growth plate chondrocytes.

Total Condylar Unipolar Expandable Prosthesis for Proximal Tibia Malignant Bone Tumors in Early Childhood

Wide resection and reconstruction of tumors of the proximal tibia in the pediatric population are challenging procedures. The use of hinged, expandable prostheses may cause early closure of the distal femoral growth plate, which may increase the risk of limb discrepancy already present in this population. Between 1991 and 2001, 2 girls and 1 boy, aged 6, 6, and 4 years, respectively, were diagnosed with osteosarcoma of the proximal tibia and treated with wide resection and reconstruction with a condylar unipolar expandable tibial prosthesis. A press-fitted technique was used for component insertion. All patients received neoadjuvant and adjuvant chemotherapy. Radiographic and functional follow-up took place at least once a year for a minimum of 4 years. Adequate pain control, limb-length equality, and acceptable function were obtained in all patients. One patient presented with significant range of motion reduction (0°- 30°) in the affected knee. Limb lengthening was performed as needed to maintain balanced limb length. All patients had a good Musculoskeletal Tumor Society category score. No complications occurred in terms of component loosening or infection. One patient died shortly after 4-year follow-up because of doxorubicin-induced leukemia. Currently used hinged, expandable prostheses can jeopardize the unaffected distal femoral growth plate. This article describes a technique of reconstruction that spares the distal femoral growth plate. Adequate limb length can be expected with acceptable functional outcome. However, it is imperative to keep in perspective the expectations of the physician, the physician's team, the patient, and the patient's family.

Coordinated tether formation in anatomically distinct mice growth centers is dependent on a functional vitamin D receptor and is tightly linked to three-dimensional tissue morphology

Bone bridges linking the epiphysis and metaphysis termed "tethers" have been found in the femoral growth plates of C57Bl/6 mice and are disrupted when the vitamin D receptor (VDR) is ablated. It is unknown if tethers are found in other growth centers, if they are regulated in a comparable manner, or if they have a functional role in skeletal development or stability. To address this, distal femoral growth plates (GPs) and spheno-occipital synchondroses (SOSs) of wild-type C57Bl/6 mice from 2 to 15 weeks of age were analyzed using μCT scans. The GPs and SOSs of VDR+/+ and VDR-/- mice fed regular or rescue diets to restore mineral homeostasis until 10 weeks of age were also scanned. Tethers in GPs and SOSs both thickened and accumulated in number as these growth centers decreased in size. Ablating the VDR made GPs and SOSs rachitic and nearly eliminated tether formation. Rescue diets restored the volume of both growth centers but only partially restored growth center thickness and tether formation, suggesting that lα,25-dihydroxy vitamin D(3) partially regulates tether formation in these growth centers via its receptor. In VDR+/+ mice 2-15 weeks in age, growth center thickness was inversely correlated to animal weight whereas tether phenotype (tether volume/growth center volume, tether number/mm, tether width, tether spacing) was significantly related to animal weight. In both 2-15 week old VDR+/+ and 10 week old VDR+/+ and VDR-/- mice on normal and rescue diets, tether phenotype (tether number/mm, tether spacing) had strikingly similar relationships to growth center thickness. These results show that tethers are present in growth centers in different anatomic and undergo developmental changes in a comparable manner; in both sites, VDR-regulated tether formation is strongly linked to growth center morphology; and tether formation is associated with body weight, suggesting a role in maintaining growth plate stability during growth.

Zone of Injury of the Medial Patellofemoral Ligament After Acute Patellar Dislocation in Children and Adolescents

Background: Patellar dislocation is a common traumatic injury in the pediatric and adolescent population. The primary constraint to lateral subluxation and dislocation of the patella is the medial patellofemoral ligament (MPFL), which serves to resist lateral translation of the patella. Injury to the MPFL may predispose to recurrent dislocation but the anatomic site of injury is poorly characterized in children and adolescents. Purpose: The authors addressed 2 questions: (1) What is the zone of injury to the MPFL in a pediatric/adolescent population after primary patellar dislocation? (2) What is the location of the femoral attachment of the MPFL with respect to the growth plate? Study Design: Cohort study (prevalence); Level of evidence, 2. Methods: Patients were eligible if they were ≤18 years of age and suffered a recent patellar dislocation characterized by magnetic resonance imaging (MRI) findings of high T2-signal intensity in the lateral femoral condyle. Patients were excluded if they had a history of prior dislocations, prior knee surgery, or congenital dislocation. Two musculoskeletal radiologists and an orthopaedic resident reviewed MRI scans of 43 children. The MPFL was divided into 3 zones: patellar insertion, femoral insertion, and midsubstance. The zone of injury was confirmed by the presence of associated soft tissue edema on short tau inversion recovery sequences and the distance from the MPFL insertion to the medial distal femoral growth plate was measured. Associated injuries were noted and the Insall-Salvati ratio was measured. Results: The MPFL injury was isolated to the patellar attachment in 61% of patients and to the femoral attachment in 12%. Twelve percent of patients had injury at both the patellar and femoral attachments. Six percent had no identifiable MPFL injury and 9% had combinations of midsubstance and either patellar or femoral attachment injuries. The kappa value for injury determinations was 0.71, indicating substantial concordance. The MPFL insertion site averaged 5 mm distal to the medial physis. Eighty-six percent of patients had an MPFL insertion distal to the growth plate, 7% had an insertion at the physis, while only 7% had a proximal insertion. The incidence of associated chondral injuries, the value of the Insall-Salvati ratio, and the location of MPFL insertion did not vary significantly with location of MPFL injury. Sixteen patients (36%) had MPFL insertions that were within 5 mm (either proximal or distal) of the growth plate. Conclusion: The zone of MPFL injury in a pediatric population after primary patellar dislocation was predominantly isolated to the patellar attachment (61%), in contrast to previous literature. Twelve percent of patients had injury only at the femoral attachment, while 12% of patients had injury to both the patellar and femoral attachments. The remaining 15% had injury at multiple locations or no identifiable injury. The MRI finding that the anatomic insertion of the MPFL is distal to the physis in 93% of patients and that the MPFL is more likely to be injured at the patellar attachment has important implications in the surgical reconstruction of the MPFL in pediatric or adolescent patients.

Growth Disturbance After Distal Femoral Growth Plate Fractures in Children: A Meta-Analysis

Growth disturbance of the distal femur is the most common complication after distal femoral growth plate fracture. The purpose of our study was to pool data from the literature to determine the incidence of growth disturbance in relation to the Salter-Harris (SH) classification. Additionally, we evaluated the potential influence of fracture displacement and treatment method. A structured PubMed search was performed to identify all reports on distal femoral growth plate fractures published in the English language literature, from 1950 to 2007. Reference lists from identified articles and bibliographies from standard pediatric fracture texts were also scrutinized. For a study to be included in this review, it needed to have at least 10 patients with a minimum of 1 year follow-up and be published in the English language. A total of 16 articles met the criteria for inclusion, which accounted for 564 fractures. Of the 564 fractures, 291 (52%) had a growth disturbance. Growth disturbance occurred in 36% of SH 1 fractures, 58% in SH 2, 49% in SH 3, and 64% in SH 4 fractures. In studies with patient-level data, there was growth disturbance in 65% of fractures with displacement and 31% of the fractures with no displacement had growth disturbance. The odds of a displaced fracture having growth arrest was 4 times greater than that of a nondisplaced fracture having a growth arrest. (P = 0.0015) In the studies with patient-level data, 58% (70/121) of fractures treated without fixation developed a growth disturbance, with 37% (45/121) being a clinically significant disturbance. Of the patients treated with fixation, including those who were initially treated without but lost reduction, 63% (19/30) developed a growth disturbance, with 27% (8/30) being clinically significant. Significant growth disturbance was defined as a leg length discrepancy equal to or greater than 1.5 cm and/or 5 degrees of varus or valgus deformity. SH 4 fractures had the greatest incidence of developing a leg length discrepancy greater than 1.5 cm (9/37). Twenty-two percent (112/506) of all distal femoral growth plate fractures developed a leg length discrepancy of greater than 1.5 cm. Fifty-two percent of distal femoral growth plate fractures had some form of growth disturbance. Twenty-two percent (112/506) of all distal femoral growth plate fractures developed a leg length discrepancy of greater than 1.5 cm. SH 1 fractures had the lowest incidence of growth disturbance (36%), whereas SH 4 fractures had the highest rate of growth disturbance at 64%. Although there is a greater incidence of growth disturbance in patients who were treated with fixation (58% versus 63%), there was a decreased incidence of significant growth disturbance (37% versus 27%).

Formation of Tethers Linking the Epiphysis and Metaphysis Is Regulated by Vitamin D Receptor-Mediated Signaling

Rat tibial growth plates have X-ray opaque tethers that link the epiphysis and metaphysis and increase with age as the growth plate (GP) becomes thinner. To determine if tether formation is a regulated process of GP maturation, we tested the hypotheses that tether properties and distribution can be quantified by micro-computed tomography (microCT), that rachitic GPs typical of vitamin D receptor knockout (VDR(-/-)) mice have fewer tethers and altered tether distribution, and that tether formation is regulated by signaling via the VDR. Distal femoral GPs from VDR(+/+) and VDR(-/-) 8-week-old mice were analyzed with microCT and then processed for decalcified and undecalcified histomorphometry. A wide range of parameters that assessed GP and tether geometry and morphology, along with tether distribution, were measured using both microCT and histology. Growth plates of 10-week-old VDR(+/+) and VDR(-/-) mice on a high-calcium, phosphorus, lactose, and vitamin D(3) rescue diet were also analyzed. Both microCT and histology showed tethers present throughout normal mice GPs, while reduction in tether number and volume percentage occurred in VDR(-/-) GPs with localization to the central region. Decreased shrinkage in the axial direction during decalcified histological processing correlated with tether formation, suggesting mechanical stability due to tethers. Tether formation increased greatly between 8 and 10 weeks. Rescue diets restored VDR(-/-) GP size but not tether volume percentage. Overall, these results demonstrate microCT imaging's utility for analyzing tether formation and suggest that signaling via the VDR plays a pivotal role in tether formation.

Amputation in the growth period

Amputations during childhood and juvenile age differ from those in adults: Osseous over-growth can be expected especially in trans-humeral and trans-tibial stumps,--to be prevented by stump-capping. After loss of a growth-plate transosseous stumps will reduce growth; therefore it is crucial to preserve the distal femoral growth-plate and a weight-bearing knee-disarticulation stump with respect to future prosthetic function and appearance. Besides predominantly traumatic origin of acquired amputations in the growth-period longitudinal deficiencies present at birth have to attract utmost attention when decision-making for surgical conversion--e.g. of a missing tibia to a knee-disarticulation stump or severe fibular deficiency to a weightbearing Symeor modified Pirogoff-/Boyd-stump. The multiple limb-deficient child and adolescent depends on a holistic approach towards therapy provided by specialised centers.

Electrical stimulation of the growth plate: A potential approach to an epiphysiodesis

Epiphysiodesis is an operative procedure that induces bony bridges to form across a growth plate of a bone to stop longitudinal growth. This is a very common orthopedic procedure to correct disproportional long-bone growth discrepancies; however, present techniques require an operation and anesthesia. Our study was designed to develop a minimally invasive method of epiphysiodesis by using electrical stimulation with DC current. In a rabbit model, a thin titanium electrode was inserted into a single location of the distal femoral growth plate in three groups: one without current (control), one group with a constant 10 microA (low current, LC), and one group with a 50 microA (high current, HC). The current was delivered for 2 weeks. The nontreated femur served as a control for each animal. Femur lengths were measured and comparisons were made between operated (left) and nonoperated (right) femurs. Digitized histomorphometric and volumetric analyses were performed on each growth plate, and detailed assessments were made of any morphological changes. Using length measurements, the difference in femur length was significantly larger in the HC group and not in the LC or control groups, showing bone growth inhibition at the higher current. In the HC group, bony bridges and disorganized growth plates were observed. This study shows that delivery of an electrical current of 50 microA for as little as 2 weeks can markedly affect bone growth as evidenced by changes in epiphyseal plate volume and architectural organization, and the study supports the use of this minimally invasive approach as a potential method of achieving an epiphysiodesis.

Morphological alterations in the growth plate cartilage of ovariectomized mice

The effects of ovariectomy on growth and estrogen receptor (ER) expression level in the epiphyseal growth plate in mice have been estimated by histomorphometry and immunohistochemistry. Twelve female ddY mice, 8-9 weeks of age, were subjected to bilateral ovariectomy and 12 others were sham operated. They were then killed 8 weeks later. Ovariectomy significantly increased the total thickness of the distal femoral and proximal tibial growth plate cartilage. Ovariectomy caused a 1.4-fold increase in the thickness of the proliferative layer in the distal growth plate of the femur and a 1.3-fold increase in the thickness of the proliferative layer in the proximal growth plate of the tibia. ERalpha and ERbeta immunoreactivity was detected in chondrocytes of the growth plate and the expression level of ERs in epiphyseal plates was increased in ovariectomized mice compared with controls. These data suggest that ERalpha and ERbeta are coexpressed in the growth plates of the mice and that the cartilage growth and the level of expression of ERs in these tissues are hormonally regulated.

CASE REPORTS: Epiphysiodesis in a Patient with Osteopetrosis

We describe a 14-year-old girl with intermediate-type osteopetrosis who presented with a 4.8-cm leg-length discrepancy secondary to premature distal femoral growth plate closure. She had a projected leg-length discrepancy of 7 cm at maturity, which was predicted using Moseley charts. The patient was treated successfully with an epiphysiodesis. Her remaining growth was predicted by Moseley charts. A percutaneous epiphysiodesis can treat leg-length discrepancies in patients with osteopetrosis.

Cyclical Intravenous Pamidronate Treatment Affects Metaphyseal Modeling in Growing Patients With Osteogenesis Imperfecta

This analysis of 50 growing patients with osteogenesis imperfecta revealed that 2-4 years of pamidronate treatment lead to abnormalities in the shape of the distal femoral metaphyses. Cyclical intravenous pamidronate therapy is of clinical benefit in children and adolescents with moderate to severe osteogenesis imperfecta (OI) but might interfere with the shaping of long bone metaphyses during growth. We evaluated the distal femur in 50 growing children with moderate to severe OI (mean age, 6.7 +/- 3.4 years; 26 girls) who had received 2-4 years of pamidronate therapy (annual dose, 9 mg/kg body weight). The mediolateral width of the distal femoral growth plate and of the metaphysis, as well as the ratio between these two measures (called metaphyseal index), were determined on lower limb radiographs. Compared with untreated OI patients who were matched for OI type and age, pamidronate-treated patients had similar growth plate width but wider metaphyses, resulting in a 26% higher metaphyseal index (p < 0.001). Apart from the effect on bone shape, each pamidronate cycle induces a transverse line in metaphyses that are adjacent to active growth plates. Analyses of these transverse lines revealed that they persist for an average time of approximately 4 years, with a range from 2 to 8 years. Pamidronate interferes with the process of periosteal resorption that is normally responsible for shaping the distal femoral metaphysis. Pamidronate-induced transverse lines disappear with time, supporting the view that these lines represent horizontal trabeculae that undergo remodeling. There is no evidence at present that these treatment induced morphological changes have any clinical implications.