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Epiphyseal plate injury in children is very common, which can be caused by fracture, infection, malignant tumors, iatrogenic injury or other causes.Growth arrest and angulation or rotation deformity after epiphyseal plate injury would seriously affect the physical and mental health of children.At present, the success rate of bone bridge resection combined with corresponding material filling is super low.The construction of bioactive epiphyseal cartilage using cartilage tissue engineering technology has become a new research direction for the treatment of epiphyseal plate injury in children.Therefore, this review focuses on the current research on the regeneration of epiphyseal cartilage from the perspective of 3 elements of tissue engineering: seed cells, growth factors, and tissue engineering scaffolds.
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Objective:To establish a model of epiphyseal plate injury in juvenile rabbits and explore the effect of periosteum flap with saphenous artery on preventing the formation of bone bridge after epiphyseal plate injury.Methods:From July 2017 to January 2018, 30 young New Zealand immature rabbit were randomly grouped into 3 groups (group A, B and C, with 10 rabbits per group). The blood vessels of knee joint were dissected and a periosteum flap with saphenous artery were designed. A model of distal femoral epiphyseal plate injury was established in immature rabbits with a 3.0 mm Kirschner wire on one side of the distal femoral epiphyseal plate as experimental side, and the other side of the distal femoral epiphyseal plate was assigned as control side. The injured epiphysis were prepared and described as follow: in experimental side of group A, a piece of periosteum with the same size as that in group C was resected and discarded. In experimental side of group B, a periosteal flap without vascular pedicle was filled in the injured area. And in experimental side of group C, a periosteum flap with saphenous artery was filled in the injured area. The length and varus angle of femur specimens of length and varus angle of femur specimens wihthin groups were measured at 24 weeks after surgery to evaluate the effect on bone growth in epiphyseal plate injury. The effect of the periosteum flap with saphenous artery on preventing a formation of bone bridge was assessed by section view of decalcified specimens, HE staining and toluidine blue staining. The measured data were expressed as Mean and standard deviation (Mean±SD), and data were compared within and between the groups using one-way analysis of variance (ANOVA). P<0.05 was considered as statistically significant. Results:The femur of experimental side of group A and B showed obvious short with valgus deformity compared with that of control side, and the difference of length and varus angle of femur specimens wihthin groups was statistically significant ( P<0.05). There were no significant differences in the length and valgus angle of the femur between experimental side and its control side in group C ( P>0.05). In experimental side of group A, there were bone bridges in the epiphyseal lesion area, with a clear boundary to the surrounding epiphyseal plate. In experimental side of group B, the periosteum flap in the injured area was absorbed, accompanied by the formation of a few pale white bone tissue, and with a clear boundary to the surrounding epiphyseal plate. In experimental side of group C, the lesion area was filled with milky white cartilage tissue with the same colour as the epiphyseal plate, and with an unclear boundary with the epiphyseal plate. HE stain and toluidine blue staining showed that the injured area of group A was filled with a large number of bone tissue, but no obvious cartilage tissue was observed. In group B, the area of lesion was filled mainly with fibrous tissue, with a small amount of bone tissue. In group C, a large number of hyaline cartilage tissues were formed along the tunnel of the injury area, and closely connected with the normal epiphyseal plate. Conclusion:Filling a periosteum flap with saphenous artery after epiphyseal plate injury can prevent the formation of bone bridge and prevent the affected limb form shortening and angulation.
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Objective: To explore the application value of quantitative T1ρ imaging in distal radial epiphyseal plate injury of teenager divers. Methods: Totally 38 young diving athletes and 25 age-, sex-matched healthy volunteers (control group) underwent bilateral wrist conventional and quantitative T1ρsequence MR scanning. According to conventional MRI, the athletes were divided into epiphyseal plate injury subgroup and no epiphyseal plate injury subgroup. T1ρ values of distal radial epiphyseal plate different of opposite the boat phrenology area, opposite the month phrenology area and the lateral area were separately measured on T1ρ pseudo-color pictures. T1ρ values of distal radial epiphyseal plate were analyzed among groups and different ROI in same groups. Results: T1ρvalue of distal radial epiphyseal plate in epiphyseal plate injury subgroup and no epiphyseal plate injury subgroup were lower than that in control group (both P0.05). Conclusion: Quantitative T1ρimaging helps to discover changes of internal ultrastructure and cell molecular level in distal radial epiphyseal plate injury of the diver.
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Objective To investigate the feasibility of 3-D printing technology in the application of proxi-mal tibial epiphyseal injury fracture surgery for teenagers. Methods Clinical materials of the 8 patients with proxi-mal tibial epiphyseal injury fracture who were admitted to our hospital from January 2014 to March 2016 were retro-spectively analyzed. CT data of all patients was collected before the surgery and was used for fracture 3-D recon-struction with Minics software to print out the 1:1 physical model. Meanwhile,surgical simulation was carried out on the 3-D model to design the internal fixation scheme,and all intraoperative operations were implemented in line with the preoperative planning. Postoperative brace immobilization and the early-stage function exercise were taken and growth situation of the affected limbs and fracture healing were observed and recorded. In line with the modified Hohl and Luck knee score standards,knee functional score was taken 12 months after the surgery. Results All pa-tients received postoperative follow-up service for 12 to 18 months,with the average of 15.3 months. All patients were bony union,with the excellent knee score rate of 100%. The full-length axis of two limbs was compared be-tween the postoperative reexamination and no premature skeleton closure. Pronation and supination of the knee,un-stable joints and other complications were investigated. No obvious differences were found among the activity of the affected limbs and 12-month growth length after the surgery and that of the uninjured side. Conclusions 3-D printing technology is a strong clinical guidance to the treatment of proximal tibial epiphyseal injury fracture surgery for teenagers.
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Objective To analyze the clinical characteristics and treatment strategy of ankle supination fracture in children.Methods From January 2012 through July 2014,89 children were treated at our department for ankle fracture caused by supination sprain according to their medical history,physical examination,X-ray films and CT three-dimensional reconstruction of the ankle.Appropriate protocols were applied on the basis of Lauge-Hansen classification,type and displacement of their fractures.Of them,52 belonged to the supination-adduction type (the extramalleolus fracture was of Odgen type Ⅶ in 51 children whose epiphyseal plate of distal fibula had not been closed),35 to the supination-extorsion type (32 cases had tri-plane fracture and 3 Tillaux fracture),and the remaining 2 did not fit the Lauge-Hansen classification.Surgical treatment was applied in 32 cases and conservative treatment in 57 ones.Results All the children received outpatient follow-up from 12 to 24 months(mean,18 months).No bone nonunion,osteoarthritis,or fracture malunion was found.The American Orthopaedic Foot & Ankle Society scores averaged 92 points (range,from 88 to 100 points) at the last follow-ups.Conclusions In children whose epiphyseal plate is nearly closed,supination-adduction sprain likely causes an extramalleolus fracture of Salter-Harris type Ⅰ or type Ⅱ,but in children whose epiphyseal plate is unclosed,an epiphyseal fracture of Odgen type Ⅶ is inclined to happen.A Tillaux fracture or tri-plane fracture at the level of distal tibiofibular syndesmosis results often from supination-extorsion sprain in children.For fractures involving epiphysis or epiphyseal plate,anatomical reduction and proper fixation are critical to functional recovery and reducing complications.
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Background: Ciprofloxacin is one of the most effective antibiotics used in the treatment of many infectious diseases in adults, but it has undesirable toxic effects on the growing cartilage. The present study was designed to detect the toxic effect of ciprofloxacin on growing cartilage in the immature albino rats and the possible protective role of magnesium in prevention of such toxicity. Methods: Seventy rats were used in the current study. They were divided into five groups Group I: control group, group II: ciprofloxacin treated group, group III: magnesium given before ciprofloxacin, group IV: ciprofloxacin with magnesium and group V: magnesium given after ciprofloxacin). The region of the knee joint was prepared and stained with hematoxylin and eosin stain for light microscopic examination. Morphometric studies were also done using the image analyzer. Results: ciprofloxacin treated group revealed different changes in the tibial epiphyseal growth plate of juvenile rats in the form of decreased thickness, loss of chondrocytes, karryorrhexis, pyknotic nuclei, interlacunar hemorrhage, irregularity in the columns and myxomatous degeneration. Partial improvement was observed in the group treated with magnesium before ciprofloxacin and in the group treated with magnesium concurrently with ciprofloxacin, meanwhile no improvement was detected in the group treated with magnesium given after ciprofloxacin. Conclusion: The present study concluded that the use of ciprofloxacin in juvenile rats caused epiphyseal plate growth retardation; accordingly the use of this drug in pediatrics should be restricted to carefully selected indications. Owing to its protective role in reducing such chondrotoxic effects, the use of magnesium before (in chronic cases like cystic fibrosis of the lung) and concomitantly with ciprofloxacin is highly recommended.
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Objective To explore the clinical efficacy of minimally invasive implantation figure-ofeight steel plate in treatment of children with lower limb angular deformity caused by a variety of reasons.Methods The clinical data of 35 lower limb angular deformity children who treated with minimally invasive implantation figure-of-eight steel plate half epiphyseal plate block method were retrospectively analyzed.During pre-operation and post-operation,the X-ray of both lower limb was shoot,the mechanical axis of lower limb and femoral tibial angle (FTA) were measured,and the clinical efficacy combining clinical results was assessed.Results All the children were completed the follow-up,the average follow-up was 15 (13-20)months.The 35 children with lower limb angular deformity achieved satisfactory correction and restored normal the mechanical axis of lower limb.All children were normal,and no complications of epiphyseal plate injury were found,except 1 child appeared incision fat liquefied and healed after secondary wound debridement and suture.Conclusions Minimally invasive implantation figure-of-eight steel plate half epiphyseal plate block method in treatment of the children with lower limb angular deformity is simple,cheap,effective,needless osteotomy,well tolerated and with less complications.It is an easily learned technique for osteology surgeons and to be worth generalization at clinical especially those hospitals without establishing special department of children' s osteology.
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The aim of this study was to conduct a literature review of impacts of protein malnutrition and/or early food deprivation on the formation of the growth plate in young animals. A search was performed using the databases PubMed/MEDLINE, LILACS, SciELO and the Cochrane Library, without language restrictions or any limit as to year. Initially, 150 articles were identified, however, after application of the inclusion and exclusion criteria only five remained. In three studies the nutritional stress was due to protein malnutrition, another due to fasting and the fifth was due to food restriction. All the studies had some methodological omissions. The studies included in this review-demonstrated corroboration in the results obtained, regardless of whether the animals had been subjected to protein malnutrition, fasting or food restriction. The findings uncovered were reduction in height of the epiphyseal plate, in the number of proliferative and hypertrophic chondrocytes, in the bone growth rate and in the longitudinal length of the bone in animals subjected to nutritional stress. In this systematic review, it was possible to observe the susceptibility of the epiphyseal plate in the first place, and secondarily, of the long bones to the effects of nutritional stress by means of protein malnutrition or food deprivation applied in young animals.
El objetivo fue realizar una revisión de la literatura sobre el impacto de la desnutrición proteica y/o privación de alimentos en la temprana formación de la placa de crecimiento en animales jóvenes. La búsqueda fue realizada en las bases de datos PubMed/MEDLINE, LILACS, SciELO y Biblioteca Cochrane sin restricción de lengua o límite de año. Fueron identificados inicialmente ciento cincuenta artículos que, posterior a la aplicación de los criterios de inclusión y exclusión, solo quedaron cinco. En tres estudios el estrés nutricional fue causado por la desnutrición proteica, otro al ayuno y el tercero fue por restricción alimentaria. Todos los estudios presentaban algunas omisiones metodológicas. Las investigaciones incluidas en esta revisión demostraron concordancia en sus resultados obtenidos, independientemente que los animales hayan sido sometidos a desnutrición proteica, ayuno o restricción alimentaria. Los datos obtenidos mostraron que los animales sometidos al estrés nutricional presentaron una reducción en la altura de la placa epifisaria, en el número de condrocitos proliferativos e hipertróficos, en la tasa de crecimiento óseo y en la longitud ósea. En esta revisión sistemática fue posible observar que los efectos del estrés nutricional, a través, de desnutrición proteica o de la privación alimentaria aplicada en animales jóvenes presentan, en primer lugar, una susceptibilidad de la placa epifisaria y de los huesos largos de manera secundaria.
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Animals , Bone Development , Food Deprivation , Growth PlateABSTRACT
Objective: To assess the influence of absorbable poly-D, L-lactide acid (PDLLA) rods on the development of epiphyseal plate after implanted into the distal femoral epiphysis in skeletally immature New Zealand white rabbits. Methods: Seventy-five New Zealand white rabbits were evenly randomized into 3 groups according to the diameter of rods: 1.5 mm PDLLA rod group, 2.2 mm PDLLA rod group, and 3.2 mm PDLLA rod group. The absorbable PDLLA rods were placed into a drill hole of equal size in the intercondylar portion of the right femur, crossing the central portion of epiphyseal plate; empty drill holes of same size were made across the left femoral physis, which served as a control. The area of injured epiphyseal plates was calculated before operation. The animals were sacrificed at 3, 6, 9, 12 and 24 weeks after operation. Measurement of femur bone length, radiographic measurement of both knee joint valgus angles, histology sections and transmission electron microscopic examination of the physis and adjacent bones were performed to evaluate the influence of implanted rods on epiphyseal plate. Results: The proportions of injured area caused by the drill holes in 1.5 mm group, 2. 2 mm group, and 3.2 mm group were (1.86±0.10)%, (4.03±0.52)% and (7.52±1.02)%, respectively. At 24 weeks after operation, femur bone lengths (mm) of experimental and control sides were 90.60±0.55 and 90.27±0.84 in 1.5 mm group,87.53±0.67 and 87.06±0.78 in 2.2 mm group, and 85.30±1.39 and 84.91±1.40 in 3.2 mm groups, respectively; their knee joint valgus angles (°) were 7.863±1.26 and 8.110±1.18 in 1.5 mm group, 8.858±1.30 and 9.453±1.95 in 2.2 mm group, and 11.90±2.80 and 14.448±5.17 in 3.2 mm group, respectively. There was no significant difference in femur lengths and valgus angles between 2 sides in each group (P>0.05). Both femur bone lengths in 3.2mm group were shorter than those in the 1.5 mm and 2.2 mm groups. No abnormalities of cartilage cells were observed, without obvious histological evidence of inflammation; only nonspecific foreign body reaction and macrophage infiltration were noticed. Conclusion: PDLLA rod itself does not cause any disturbance to the development of the epiphyseal plate. The growth disturbance of epiphyseal plate depends on the area of injured epiphyseal plate; a injured area over 7% of epiphyseal plate may cause the growth disturbance of epiphyseal plate.
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Nowadays,more and more basic and clinical researches on absorbable internal fixators are car- fled out in China.This paper reviews the recent researches on biodegradation,absorption,and mechanical prop- erties of absorbable internal fixators,their effects on bone mineral density and structure and injury of epiphyseal plate,and their clinical applications.Some problems that have not been solved and future research key points are highlighted and discussed.
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0.05).Both femur bone lengths in 3.2mm group were shorter than those in the 1.5 mm and 2.2 mm groups.No abnormalities of cartilage cells were observed,without obvious histological evidence of inflammation;only nonspecific foreign body reaction and macrophage infiltration were noticed.Conclusion: PDLLA rod itself does not cause any disturbance to the development of the epiphyseal plate.The growth disturbance of epiphyseal plate depends on the area of injured epiphyseal plate;a injured area over 7% of epiphyseal plate may cause the growth disturbance of epiphyseal plate.
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Objective To discuss the relationship between BMP-2 protein and possible mechanism and to compare the postive rate of two different imaging examinations in evaluating the epiphyseal plate involved by osteosarcoma.Methods Radiographic and MRI features of epiphyseal plate extension by osteosarcoma confirmed by pathology in 36 cases were analysed retrospectively.The expression of BMP-2 was detected with immunohistochemical SABC method in different part of specimen.Results The diagnostic accurate rate in evaluating the epiphyaeal plate extension from osteosarcoma by X-ray and MRI was 44.44% and 100% respectively.The positive reactive rate of BMP-2 in tumor body,epiphyseal plate soak district,normal epiphyseal plate and normal tissue nearby the tumor was 88.89%(32/36),99.44%(34/36),10.00%(1/10) and 20.00%(2/10) respectively.Conclusion MRI is more sensitive to radiography in evaluating the epiphyseal plate involved by osteosarcoma,the higher positive reactive rate of BMP-2 protein is correlated to the epiphyseal plate extension of osteosarcoma.
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To understand the expression of hoth TGF-beta l and II ligands and the receptors, artificial fracture was made on rat femur. Fracture callus and epiphyseul plate were stained immunohistochemically on 3rd. 7th, 14th, 21st, 42nd and 56th day after trauma. Polyclonal antibody was used to stain TGF-beta I and II ligands and receptors. At epiphyseal plate, both ligand and receptor were expressed from each cell in proliferating and maturing zone. But there was no difference between type I and II except expression time. TGF-beta II ligand and receptor were expressed earlier: they were expressed mostly by the cells at the zone of proliferating cartilage but TGF-beta1 ligand and receptor were expressed mostly hy the cells at zone of maturing cartilage. At fracture site, TGF-beta expression was observed from 3rd day after trauma and it reached its maximum intensity at 2 weeks. It decreased thereafter and disappeared at 6 weeks after trauma. In enchondral ossification area, TGF-beta expressing cells were scattered throughout the enchondral mass. In intramembranous ossification area, the ligands and receptors were expressed from the osteohlasts just heneath the periosteum. ln summary, TGF-beta ligands and receptors were expressed at epiphyseal plate and fracture callus. There was no difference between TGF-beta 1 and 2 expres.ion except the appearance time at epiphyseal plate. We could not draw any conclusion about ligand and rcceptor mechanism with this immunohistochemical staining.
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Animals , Rats , Bony Callus , Cartilage , Femur , Growth Plate , Ligands , Periosteum , Receptors, Artificial , Transforming Growth Factor beta , Transforming Growth Factor beta1ABSTRACT
This study was designed to investigate the effects of burn injury of the leg on the growth plate of proximal tibia in the immature rat. The procedure for burn injury of left leg was performed at the thigh, knee and lower leg under the general anesthesia with inhalation of ether. After the burn injury, follow up observations were made at second day, 1st, 4th, and 6th weeks with histological examination. The results were as follows. During postburn 4 weeks, height of the proximal tibial epiphyseal plates of the experimental group showed significant increment, comparing with control group. At postburn 6th weeks, it revealed no significant difference, comparing with control group (Wilcoxon rank sum test, p<0.05). During postburn 4 weeks, cell numbers in column of the proximal tibial epiphyseal plates of the experimental group showed significant increment, c omparing with control group. At postburn 6th weeks, it revealed no significant difference comparing with control group (Wilcoxon rank sum test, p<0.05).
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Animals , Rats , Anesthesia, General , Burns , Cell Count , Ether , Follow-Up Studies , Growth Plate , Inhalation , Knee , Leg , Thigh , TibiaABSTRACT
During the period from 1979 to 1987, bone bridge connecting epiphysis to metaphysis was removed and replaced with a free fat transplant for partial epiphyseal plate closure in 7 patients. Bone bridge resection and free fat interposition was repeated in one patient. Average age of the patients was 9.2 years and sites of epiphyseal plate closure were distal femur in 6 patients and proximal tibia in one patient. The causes of closure were physeal fracture(4), infection(2) and a complication of intramedullary nailing(1). The mean follow-up period was 3 years 9months. Tomograms specifically determine the location and the extent of bone bridge. Successful results which mean spontaneous correction of angular deformity or decreased limb length discrepancy, were obtained in 3 patients. Although deformity recurred or limb length discrepancy was increased somehow, some benefits were obtained in another 2 patients. Benefits from the procedure was negligible or questionable in 2 patients. The poor results were seemingly related to physeal closure following infection and larga size of bone bridge. Bone bridge resection and free fat interposition was considered to be effective method for the treatment of the partial epiphyseal plate closure in the selected cases.
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Humans , Congenital Abnormalities , Epiphyses , Extremities , Femur , Follow-Up Studies , Growth Plate , Methods , TibiaABSTRACT
It is essential to define the accurate location and extent of bony bridge in relation to the epiphyseal plate for operation of partial epiphyseal plate closure by bony bridge resection. Since magnetic resonance imaging(MRI) provides excellent tissue contrast and multiplaner image, it could be applied to the diagnosis and mapping of bony bridge of epiphyseal plate. A thirteen year old female with post-traumatic epiphyseal injury of ankle was diagnosed by MRI. We could assess the bony bridge accurately by direct sagittal and coronal images and excellent tissue contrast of MRI.
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Female , Humans , Ankle , Diagnosis , Growth Plate , Magnetic Resonance ImagingABSTRACT
It was reported that many adverse effects occurred to the growth areas of the adolescent player due to repititous strain. The injuries mainly involved in the shoulder and elbow, and named as little leaguers Shoulder and Little Leaguers: Elbow in boy baseball player. But the stress fracture of olecranon epiphyseal plate was rare and reported in a few cases. We reported a case observed in an adolescent Judo Player.
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Adolescent , Humans , Male , Baseball , Elbow , Fractures, Stress , Growth Plate , Martial Arts , Olecranon Process , ShoulderABSTRACT
In paediatric orthopaedic, it has been discovered that the fracture of the epiphyseal plate may cause not only growth disturbances but also progressive deformity upon appendicular skeleton of a growing child. Between 1972 May and 1983 April, 102 inward patients(106 cases) who were 18 years old or younger were treated in the department of orthopaedic surgery of Hanyang University Hospital because of epiphyseal plate fractures. The results were summerized as followings: 1. The peak age was from 5 years to 14 years(average, 10.2 years old). 2. The sex ratio was 4.3 for male to 1 for female. 3. The left side was involved more frequently than the right extremity. 4. The most common cause of fractures was injury on fall down(in 41.4% of all cases). 5. The incidence of epiphyseal fracture was 8.1% of fracture in children. 6. The most common fracture was developed at humeral epiphysis. 7. The most common type of epiphyseal fracture was Salter and Harris type IV. 8. The 50.5% of all cases was treated by closed reduction and cast immobilization, 48.1% by open reduction and internal fixation, and 1.9% by closed reduction and traction. 9. The average period of immobilization was 5.2 weeks. 10. The incidence of complication of all cases was 13.2%, but only 2 cases of them(1.9%) were needed for operation because of their complication.
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Child , Female , Humans , Male , Clinical Study , Congenital Abnormalities , Epiphyses , Extremities , Growth Plate , Immobilization , Incidence , Sex Ratio , Skeleton , TractionABSTRACT
Fractures of the femoral neck in children are rare and usually occur as a result of severe trauma. They are one of the most challenging injuries to treat. Their complication rate is high and their anatomic and physiologic characteristics make treatment difficult. The commonly encountered complications are avascular necrosis, nonunion, coxa vara and premature fusion of epiphyseal plate. Treatment of these fractures remains an unsolved problem but accurate reduction held with adequate internal fixation would appear to offer the best chance for succesful results. We report our observations in the treatment of eighteen cases of fracture of the femoral neck in children. Included is a review of references. The results obtained are as follows: 1. Among 18 patients, 11 were boys and 7 were girls. the highest incidence was between the ages of 5 and 7 years. 2. The main causes of fractures were traffic accidents in 10 cases (55.5%), falling from a height, and slipping down. 3. The commonest type of fracture was the cervicotrochanteric type (47.4%). Twelve cases were displaced fractures (66.7 %). 4. The range of Pauwels angle varied from 20° to 70°. 5. The commonly associated injuries were pelvic bone fractures, extremity fractures, skull fractures and soft tissue injuries. 6. Nine cases were treated by skin traction and plaster cast. Five cases ere treated by closed reduction and internal fixation with K-wires or knowles pins. 7. In 13 of the 18 cases, follow-up studies were done for an average period of 18 months. 8. The results were analyzed according to the Ratliffs assessment. Among the 13 cases, 10 cases showed good results, two fair and one poor. 9. All cases treated by closed reduction and internal fixation showed good results without complications. 10. Complications developed in five cases (38.5%), three cases of avascular necrosis and two cases of coxa vara. Among these five cases, one case of avascular necrosis developed as a result of neglect of the fracture and the others as a result of too conservative a treatment. 11. Secondary treatment of trochanteric arthroplasty was required in only one neglected case. This was further by avascular necrosis and the results were poor. 12. As a result, we recommond closed reduction and internal fixation as the most favorable method of treatment for the fracture of the femoral neck in children.
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Child , Female , Humans , Accidental Falls , Accidents, Traffic , Arthroplasty , Casts, Surgical , Clinical Study , Coxa Vara , Extremities , Femur , Femur Neck , Follow-Up Studies , Growth Plate , Incidence , Methods , Necrosis , Pelvic Bones , Skin , Skull Fractures , Soft Tissue Injuries , TractionABSTRACT
Five young rabbits were divided into 5 groups (2, 4, 6, 8 and 12 week), one rabbit in each group.A special collision unit was used in the experiment by which the distal ends of the right fore legs of rabbits were struck repeatedly. Altrastructure changes of chondrocyte at the epiphyseal plate in the distal endof radius were observed in H-500 electron microscope. In two and four week groups, organaelles swelling was found such as rough endoplasmic reticulum andmitochondria, especially mitochondria swelling which showed different shapes like sausagge and racket.Space around nucleus increased, nucleus shape changed, myeline structure in the mitochondria and chroma- tin margination in the nucleus were found in the six and eight week groups. Altrastructure changes weremore serious in the eight and twelve week groups than other groups. Necrosis of chondrocyte was appearedsuch as part organaelles dissolved or disappeared, nucleus brokeu aud nucleus memberane disappeared. The results showed in altrastructure pathology that chronic collision injury can cause not only degeneration of chondrocyte in the pressure epiphyseal plate but necrosis of chondrocyte as well. It concluses that chondrocyte necrosis is related to local ischemia resulted from chronic collision injury.