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Background: Several methods are available to estimate leg lengths at maturity to facilitate the determination of timing of epiphysiodesis. We compared the Paley multiplier, Sanders multiplier, and White-Menelaus methods in an epiphysiodesis-aged cohort. We assessed intra- and interrater reliability for Sanders skeletal stages and Greulich and Pyle atlas skeletal age., Methods: Actual growth was recorded in healthy, unoperated femoral and tibial segments from an epiphysiodesis database. The predicted and actual lengths were compared with use of the Paley multiplier and White-Menelaus methods, Greulich and Pyle skeletal age, and the Sanders multiplier using Sanders stages. Intra- and interrater reliability were assessed in a separate group of 76 skeletal age films., Results: The cohort included 148 femora and 195 tibiae in 197 patients. Femoral length at maturity was slightly underestimated by the Sanders multiplier and staging, was overestimated by the Paley multiplier and skeletal age, and was most accurately predicted with use of the White-Menelaus formula and skeletal age. All methods overestimated tibial length at maturity. The whole-leg prediction accuracy of the Sanders multiplier and White-Menelaus formula were comparable and were more accurate than that of the Paley multiplier. For Sanders skeletal staging, the interrater reliability varied from 0.86 to 0.88 and the intrarater reliability varied from 0.87 to 0.96. For Greulich and Pyle skeletal age, the interrater reliability varied from 0.87 to 0.89 and the intrarater reliability varied from 0.91 to 0.95., Conclusions: Use of the Sanders multiplier and skeletal stages was more accurate than the Paley multiplier and skeletal age in this cohort. Use of the White-Menelaus formula and skeletal age was slightly more accurate in predicting femoral length and slightly less accurate in predicting tibial length compared with the Sanders multiplier. Intra- and interrater reliability were similar between Sanders skeletal stages and Greulich and Pyle atlas skeletal age. The White-Menelaus formula and skeletal age was the recommended method for predicting lower-extremity segment lengths at maturity and epiphysiodesis effect. Although easier to recall without referencing an atlas and not sex-specific, Sanders skeletal staging does not correspond directly to years of growth remaining, and thus cannot be used with the White-Menelaus formula., Clinical Relevance: The Greulich and Pyle atlas to determine skeletal age and the White-Menelaus formula to determine growth remaining are reliable predictors of epiphysiodesis effect in the lower extremities., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/G586)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: The ability to estimate skeletal maturity using a knee radiograph would be useful in anterior cruciate ligament (ACL) injuries and limb-length discrepancy in immature patients. Currently, a quick, accurate, and reproducible method is lacking., Methods: Serial knee radiographs made 3 years before to 2 years following the chronologic age associated with 90% of final height (an enhanced skeletal maturity gold standard compared with peak height velocity) were analyzed in 78 children. The Pyle and Hoerr (PH) knee method was simplified by developing discrete stages for the distal part of the femur, the proximal part of the tibia, the proximal part of the fibula, and the patella. The Roche-Wainer-Thissen (RWT) knee method was simplified from the 36 original parameters to 14 parameters by removing parameters that were poorly defined, were not relevant to the peripubertal age range, were poorly correlated with 90% final height, or were poorly reliable on a 20-radiograph pilot analysis. We also compared the recently described central peak value (CPV) of the distal part of the femur. The Greulich and Pyle (GP) left-hand bone age was included for comparison., Results: In this study, 326 left knee radiographs from 41 girls (age range, 7 to 15 years) and 37 boys (age range, 9 to 17 years) were included. Stepwise linear regression showed higher correlation in predicting years from 90% final height using the modified RWT and demographic characteristics (R2 = 0.921) compared with demographic characteristics alone (R2 = 0.840), CPV and demographic characteristics (R2 = 0.866), GP and demographic characteristics (R2 = 0.899), and PH and demographic characteristics (R2 = 0.902). Seven parameters were excluded from the RWT and demographic characteristics model using stepwise linear regression and generalized estimating equations analysis, leaving 7 parameters (2 femoral, 4 tibial, and 1 fibular) in the final model. Compared with RWT and demographic characteristics (R2 = 0.921), there were minimal incremental increases by adding CPV (R2 = 0.921), GP (R2 = 0.925), or PH (R2 = 0.931)., Conclusions: This large analysis of knee skeletal maturity systems isolated 7 discrete radiographic knee parameters that theoretically outperform the GP bone age in estimating skeletal maturity., Clinical Relevance: We present a modified knee skeletal maturity system that can potentially preclude the need for additional imaging of the hand and wrist in reliably estimating skeletal maturity., Competing Interests: Disclosure: The authors indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work (http://links.lww.com/JBJS/G328)., (Copyright © 2021 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Guided growth is most commonly utilized about the knee and ankle for the correction of coronal-plane deformities by the use of plates positioned perpendicular to the physis. Sagittal-plane deformity correction has been described as well. The purpose of our study was to examine the ability to affect axial-rotational growth. Our hypothesis was that placement of plates in an oblique orientation relative to the physis can induce rotational growth deformity., Methods: Our hypothesis was tested with use of a mathematical model and a bone model and subsequently in a rabbit model. Thirteen six-week-old rabbits underwent a rotational guided growth procedure involving the distal aspect of the right femur, with a sham procedure performed on the left side. Two plates were positioned in an oblique orientation relative to the physis, medially and laterally, to guide either internal or external rotational growth. After the rabbits were killed six weeks after the surgery, the femoral rotational profile was assessed by computed tomography scans of the dissected femora and the growth plates were examined histologically., Results: A significant effect on the rotational profile was found in the treated femora. When the plates were positioned to guide external rotation, the rotational profile was significantly greater in the treated femora (29.0° compared with 11.3° in the sham femora; p = 0.008). There was a positive linear correlation between the right-left difference in rotational profile and the change in inter-plate angle (R2 = 0.72, p = 0.001). Every 1° of inter-plate angle change induced 0.367° of rotational profile difference (p = 0.001). Histologically, a swirling effect of the physeal cell columns was seen in the treated femora., Conclusions: Guided growth using plates was demonstrated to alter axial-rotational growth in a predictable fashion in a rabbit model., Clinical Relevance: Guided growth using plates may be effective for correction of rotational and multiplanar deformities.

Background: An investigation of matrix metalloproteinase-9 (MMP-9) and its influence on vascular invasion in the secondary ossification center at the chondroepiphysis of developing long bones was undertaken. The effect of MMP-9 was compared with that of basic fibroblast growth factor (b-FGF), a potent angiogenic factor, and we assessed the chorioallantoic membrane (CAM) culture as a model for angiogenesis in osteochondral tissue., Methods: Seventy-two femoral and seventy-two humeral heads of thirty-six four-day postnatal rabbits were dissected immediately after each animal was killed. Solutions of MMP-9, b-FGF, and phosphate-buffered saline solution were applied, and the femoral and humeral chondroepiphyseal explants were incubated for ten days in CAM culture. This was used as an in vivo model to investigate the growth of blood vessels into the femoral and humeral heads of the neonatal rabbit. The explants were harvested from the CAM culture and analyzed histologically. A three-day incubation was also performed to look for early signs of vascular ingrowth into the cartilage matrix., Results: One hundred and twenty epiphyses from thirty rabbits were placed onto CAM culture successfully; of these, two were harvested at three days to assess early changes and 118 were harvested at ten days. Forty of the 118 cultures were still viable when harvested after ten days, giving a 33% yield. Both MMP-9 and b-FGF caused an increased vascular invasion into the chondroepiphysis. New blood vessels derived from the chorioallantoic membrane within cartilage canals were more numerous in MMP-9 treated epiphyses, and larger canals were more commonly seen when compared with a control group., Conclusions: These findings confirmed that b-FGF is angiogenic at the chondroepiphysis. Matrix metalloproteinase-9 appears to be implicated in vascular invasion and induces the formation of new cartilage canals at the chondroepiphysis. The CAM culture model was a useful model for investigating angiogenesis in osteochondral tissue., Clinical Relevance: This study adds to the understanding of the complex biochemical interaction that occurs in cartilage when the advancing vasculature begins growing into the chondroepiphysis. A better knowledge of this angiogenic process will enable a better understanding of the pathological failure or disturbance of vasculogenesis, which results in dysplastic growth disorders and osteonecrosis.

Background: The availability of radioprotectant drugs that selectively protect normal cells but not tumor cells has rekindled interest in the effects of irradiation on the growth plate. The purpose of the present study was to quantitatively examine the sequential histomorphometric effects of irradiation and pretreatment with a free radical scavenger radioprotectant, amifostine, on the growth plate over time., Methods: Sixty four-week-old male Sprague-Dawley rats were randomized into five groups of twelve animals that were to be killed at 0.5, one, two, three, or four weeks after irradiation. One-half of the animals also received amifostine (100 mg/kg) prior to irradiation. In all animals, the right knee was treated with a single 17.5-Gy dose of radiation. End points were assessed with quantitative histomorphometric analysis of the growth plate, BrdU labeling for evidence of proliferation, evaluation of chondroclast cellularity, and determination of growth rates by means of oxytetracycline labeling., Results: The mean lengths of the femur, tibia, and hind limb continued to increase at each time-interval following treatment, but by one week the mean limb length was 4% less on the irradiated side than on the control side, and this difference remained significant for four weeks (p < 0.05). The proximal tibial growth rate decreased during the first week to 18% of the control level. Nevertheless, growth continued even at the earliest time-periods, began to return toward normal at two weeks, and ultimately returned to at least 80% of normal by four weeks after irradiation. The area fraction of matrix in the hypertrophic zone increased initially and returned to control levels at three and four weeks. The administration of the radioprotectant resulted in significant increases in growth, growth rate, growth plate height, hypertrophic zonal height, and chondroclast profiles compared with the values for limbs in which irradiation had not been preceded by treatment with amifostine., Conclusions: We found an initially profound but transient direct inhibitory effect of irradiation on growth plate chondrocytes. Recovery of growth plate function after irradiation corresponded temporally with the appearance of newly formed islands of proliferating chondrocytes. Accumulation of matrix led to a transient increase in overall growth plate height, which was most pronounced in the hypertrophic zone. This was due, in part, to the sensitivity of chondroclasts to irradiation. The radioprotectant amifostine reduced these effects on growth rate, growth plate height, matrix accumulation, and limb length.

Background: Lateral growth disturbance of the capital femoral epiphysis is the most common type of physeal arrest complicating the treatment of developmental hip dysplasia. Although this type of physeal damage has been assumed to result in poor acetabular development, the natural history of dysplastic hips affected by this pattern of growth disturbance is still unclear. To investigate this issue, we evaluated acetabular development in a retrospective study of fifty-eight hips in forty-eight patients who had lateral physeal arrest after management of developmental hip dysplasia., Methods: Of the fifty-eight hips, thirty-six were reduced closed and twenty-two were reduced open. The average age of the patients was twenty-two months (range, three to ninety-seven months) at the time of the reduction and twenty-one years (range, ten to fifty-five years) at the time of the latest follow-up evaluation. Hips rated as Severin class I (an excellent result) or II (a good result) were defined as having a satisfactory result, and those rated as Severin class III (a fair result) or IV (a poor result) were considered to have an unsatisfactory result. Specific femoral head changes were sought in the complete radiographic files on all hips. Various radiographic parameters of hip integrity, including the degree of lateral tilt of the capital femoral epiphysis, were measured over time, and comparisons were made between hips classified as satisfactory and those classified as unsatisfactory at four time-points: before the reduction, at two years after the reduction, at six to eight years of age, and at the time of the final follow-up., Results: Lateral growth disturbance of the capital femoral epiphysis was first evident by an average of ten years of age (range, four to fourteen years of age). There was no consistent early pattern of changes in the epiphysis, physis, or metaphysis related to later development of valgus tilt of the epiphysis. Thirty-four hips (59 percent) were rated as satisfactory and twenty-four were rated as unsatisfactory at the latest follow-up evaluation. Hips classified as unsatisfactory exhibited poor acetabular development by an average age of seven years. The inclination of the epiphyseal plate became progressively more horizontal or even reversed over time; however, serial measurements of inclination were not significant predictors of Severin classification., Conclusions: Lateral growth disturbance of the capital femoral epiphysis is not necessarily associated with poor acetabular development, as when dysplasia does occur it is generally evident prior to the identification of the physeal arrest. It is important to monitor acetabular development after reduction rather than search for radiographic changes of physeal arrest, which are difficult to detect in young children.

Background: In patients with a congenital or developmental limb-length discrepancy, the short limb grows at a rate proportional to that of the normal, long limb. This is the basis of predicting limb-length discrepancy with existing methods, which are complicated and require multiple data points. The purpose of our study was to derive a simple arithmetic formula that can easily and accurately predict limb-length discrepancy at skeletal maturity., Methods: Using available databases, we divided the femoral and tibial lengths at skeletal maturity by the femoral and tibial lengths at each age for each percentile group. The resultant number was called the multiplier. Using the multiplier, we derived formulae to predict the limb-length discrepancy and the amount of growth remaining. We verified the accuracy of these formulae by evaluating two groups of patients with congenital shortening who were managed with epiphysiodesis or limb-lengthening. We also calculated and compared the multipliers for other databases according to radiographic, clinical, and anthropological lower-limb measurements., Results: The multipliers for the femur and tibia were equivalent in all percentile groups, varying only by age and gender. Because congenital limb-length discrepancy increases at a rate proportional to growth, the discrepancy at maturity can be calculated as the current discrepancy times the multiplier for the current age and the gender. This calculation can be performed with use of a single measurement of limb-length discrepancy. For progressive developmental (noncongenital) discrepancies, the discrepancy at skeletal maturity can be calculated as the current discrepancy plus the growth inhibition times the amount of growth remaining. The timing of the epiphysiodesis can also be calculated with the multiplier. The predictions made with use of the multiplier method correlated well with those made with use of the Moseley method as well as with the actual limb-length discrepancy in both the limb-lengthening and epiphysiodesis groups. The multipliers derived from the radiographic, clinical, and anthropological measurements of femora and tibiae were all similar to each other despite differences in race, ethnicity, and generation., Conclusions: The multiplier method allows for a quick calculation of the predicted limb-length discrepancy at skeletal maturity, without the need to plot graphs, and is based on as few as one or two measurements. This method is independent of percentile groups and is the same for the prediction of femoral, tibial, and total-limb lengths. The multiplier values are also independent of generation, height, socioeconomic class, ethnicity, and race. We verified the accuracy of this method clinically by evaluating patients who had been managed with limb-lengthening or epiphysiodesis. The method was also comparable with or more accurate than the Moseley method of limb-length prediction.

We reviewed the long-term outcomes of treatment of fibrous dysplasia of the proximal part of the femur in twenty-two patients (twenty-seven femora). There were fifteen male patients and seven female patients. Patients who had monostotic disease had no involvement of the calcar femorale, fewer microfractures, less deformity, and stronger bone that could support internal fixation. Patients who had polyostotic disease had frequent involvement of the calcar femorale; more microfractures; severe deformity, including shepherd's crook deformity; and, in many instances, bone that could not support internal fixation. Twenty-two of the twenty-seven femora had a microfracture at the time of the initial presentation. At least one osteotomy was performed in four femora that had monostotic disease and in nine femora that had polyostotic disease. Curettage and cancellous or cortical bone-grafting did not appear to have any advantage compared with osteotomy alone in the treatment of symptomatic lesions, as all grafts resorbed with persistence of the lesion. At the time of the latest follow-up evaluation, no lesion had been eradicated or had decreased in size. A satisfactory clinical result was achieved in twenty patients (twenty-four femora): nine who had monostotic disease and eleven who had polyostotic disease. Two patients who had polyostotic disease and an endocrinopathy (one of whom had bilateral involvement) had an unsatisfactory result. All three femora in these two patients had a neck-shaft angle of less than 90 degrees at the time of the most recent follow-up evaluation. Varus deformity of the proximal part of the femur is best treated with valgus osteotomy and internal fixation early in the course of the disease. If the calcar of the femoral neck is involved or if the quality of the bone is such that internal fixation is not possible, a medial displacement valgus osteotomy can provide a more mechanically favorable position for healing of the microfracture.

The radiographs of ninety patients in whom treatment of unilateral congenital dislocation of the hip was complicated by disturbance of growth of the proximal part of the femur were studied retrospectively. All patients were followed until closure of the affected proximal femoral physis. We divided the patients into three groups, according to the degree of vascular insufficiency: patients who had mild vascular insufficiency of the hip, which had little effect on growth; those who had moderate vascular insufficiency, which produces partial arrest of growth; and those who had severe vascular insufficiency, which causes complete arrest of growth. Good correlation was found between the initial degree of vascular insufficiency and the radiographic results at the most recent follow-up. The radiographic signs that were used to predict the extent of physeal involvement were a crescent-shaped epiphysis, medial bowing of the femoral neck (a shorter and more concave curve between the lesser trochanter and the proximal femoral metaphysis [the lateral portion of the Shenton line]), lateral tilting of the capital epiphysis, and premature physeal closure. Signs that were diagnostic of existing physeal involvement were elevation of the greater trochanter and shortening of the affected extremity. The presence and severity of these signs correlated well with the degree of vascular insufficiency. Medial bowing was the most reliable prognostic factor for the determination of the fate of the hip joint at maturity.

A review of lower-extremity length-discrepancy data in 803 patients demonstrated that not all discrepancies continue to increase at a constant rate with time. A classification of the developmental discrepancy patterns identified is presented: type I, upward slope; type II, upward slope-deceleration; type III, upward slope-plateau (type IIIA, downward slope-plateau; type IIIB, plateau); type IV, upward slope-plateau-upward slope; and type V, upward slope-plateau-downward slope. The patterns are dependent on the nature of the conditions causing the discrepancies and on the place and time of their occurrence. The distribution of the types of patterns in the various etiological groups is presented. The classification of developmental patterns illustrates the varying directional changes that can occur in these discrepancies and their dependence on underlying biological phenomena. Determination of the distribution of pattern types in the various conditions aids in planning the frequency of length-discrepancy studies. The patterns alone do not provide projections of final discrepancies, but when used in conjunction with the femoral-tibial length and growth-remaining charts of Green and Anderson they permit accurate projections of discrepancy to be made.

Handedness was a more important factor in the amount of overgrowth following fractures of the femoral shaft in children in the present study than factors previously investigated. The lower limbs were measured and handedness was recorded in 112 children who had sustained their fractures fourteen to 101 months (mean, fifty-six months) before the study was undertaken. Fifty-two of these patients also had scanograms. The average overgrowth for all injured limbs was ten millimeters. The difference in the amount of overgrowth which was observed was this: when the fracture was on the same side as the dominant hand, the limb overgrew an average of eight millimeters, compared with fourteen millimeters when the fracture was on the side opposite the patient's dominant hand. This difference for the scanogram group was statistically significant (p less than 0.05). Overgrowth was significantly inhibited by overriding of fracture fragments and was enhanced by distraction. The age of the patient and the type and location of the fracture did not significantly affect overgrowth.

Growth of the femur and tibia after lengthening of their diaphyses, which had been performed several years before skeletal maturity, was assessed in eighteen patients by serial orthoroentgenograms. The rate of growth of the lengthened femora, which had been congenitally short, increased after each of seven lengthening procedures, from an average preoperative rate of 82 per cent of the normal side to 90 per cent of the normal side. The amount of surgical lengthening was similar for the femora and the tibiae, averaging 18 per cent of the preoperative length of the bone in the femora and 20 per cent of the preoperative length of the bone in the tibiae. However, the rate of growth of the lengthened tibiae decreased after each of eleven lengthening procedures (six performed for a congenital short tibia; three, for patients who had Ollier's disease; one, for a patient who had poliomyelitis; and one, for a patient who had hemangiomas), from an average preoperative rate of 88 per cent of normal to an average of 64 per cent of normal.

Although the formation of a secondary center of ossification is often compared with that of the primary center, there are striking differences between these processes. In the formation of the primary center, vascular invasion is always associated with the maturation of chondrocytes, whereas vascularization of the epiphysis can proceed in two different ways. In some species, the epiphysis is vascularized by cartilage canals before the appearance of the secondary center. However, in the mouse, the distal femoral epiphysis is vascularized by peripheral vascular invasion without pre-existing cartilage canals. Histological study of serial sections and studies of vascularization by injection with India ink demonstrated the relationship between hypertrophic chondrocyte formation, vascular invasion, and the formation of the secondary center of ossification in the murine distal femoral epiphysis.

Unlabelled: Three parameters have been identified that provide useful indices of longitudinal growth rate in rabbit epiphyseal plates. Specifically, we have examined the relationship between longitudinal growth rate and (1) growth-plate thickness; (2) the rate of cell division by proliferating chondrocytes; and (3) 35SO4 incorporation associated with matrix synthesis. There were statistically significant correlations between growth rate and each of the three experimentally determined parameters. Growth rate increased in direct proportion to growth-plate thickness, rate of chondrocyte proliferation, or 35SO4 incorporation associated with matrix synthesis. Of the three parameters, the rate of cell division of proliferative chondrocytes, as determined by counts of 3H thymidine-labeled cells following autoradiography, appeared to provide the most sensitive index of growth rate. However, used in combination, determination of the three parameters should make it possible to assess the relative contributions of changes in the numbers of cells, in the rate of chondrocyte proliferation, and in extracellular matrix synthesis to over-all growth rate., Clinical Relevance: Methods are described and data are presented that should make it possible to design studies of the factors that regulate and control the longitudinal growth rate of epiphyseal cartilage growth plates. The experimental design of this work is applicable to the study of hormonal regulation of over-all growth rates and to determination of whether the effects of certain hormones are due to their effect on cell proliferation or matrix synthesis. Such studies should contribute to a better understanding of the control of growth in normal individuals and in patients with disease.

Avascular necrosis of the hip was evaluated in two groups of patients. On group had sustained the insult to the epiphysis in infancy and had a mean growth loss in the proximal end of the femur of 21.5 millimeters at a mean age of 11.7 years. The other group had sustained the insult in mid-childhood (due to Legg-Perthes disease) and had a mean growth loss of seven millimeters at 12.4 years. Based on this evaluation, we concluded that trochanteric epiphyseodesis was nary in the latter group.

A retrospective review of fifty-three congenitally dislocated hips (in forty-four patients) in which ischemic necrosis developed was undertaken to assess patterns of growth disturbance and to establish treatment protocols. We utilized the Bucholz and Ogden classification of the four roentgenographic patterns of ischemic necrosis complicating the treatment of congenital hip disease. Patients with Type-I disease had transient ischemia with early recovery. Significant growth disturbances requiring surgical treatment were not observed. Limb-length discrepancy, increased height of the greater trochanter relative to the femoral neck and head, and problems with femoral head coverage were more likely to develop in hips with Type-II or Type-III ischemic necrosis. Equalization of limb lengths, trochanteric epiphyseodesis, and surgical means of improving femoral head coverage were also more commonly indicated in these patients. In patients with Type-IV disease, mild deformities of the femoral head and occasional limb-length discrepancies developed; other sequelae were uncommon and surgical intervention was rarely required.

Unlabelled: We have developed a procedure to transplant free autogenous iliac-crest physeal grafts into defects created in the lateral aspect of the distal femoral physis of rabbits. Excision of a portion of the lateral part of the physis led consistently to formation of a bone bridge, growth arrest, and valgus deformity. There was no evidence of increased activity by the persisting physis to fill the defect or of differentiation of mesenchymal cells into a functioning physeal layer. We carried out preliminary studies to define the optimum conditions for obtaining and transplanting a free autogenous iliac-crest physeal graft into the femoral physeal defect. The iliac apophysis is composed of a fibrocartilaginous layer, cartilage similar to epiphyseal cartilage, and a physis. The graft included the physis and some overlying epiphyseal cartilage but the outermost fibrocartilaginous layer and the surrounding perichondrium were removed, as these two tissues were believed to inhibit diffusion. The graft was separated gently from the metaphysis. Histological studies showed that the separation occurred at the lower hypertrophic-chondrocyte zone. After optimum techniques had been developed for transplantation and the feasibility of the procedure had been established in twenty-one rabbits, the capacity of the physeal transplants to prevent bone-bridge formation, growth arrest, and valgus deformity was evaluated in thirty-nine rabbits, three to four months old, using the standardized transplantation procedure. The results were assessed in terms of the gross and radiographic appearance of the femur, measurements of length, and histological characteristics. The transplanted physis retained its normal morphology, united with the residual part of the original femoral physis, and participated in endochondral bone formation. Bone-bridge formation between the femoral epiphysis and metaphysis, growth arrest, and valgus deformity were prevented or minimized in most animals, and the physeal transplants yielded good or excellent results in 60 per cent of the procedures using stringent criteria. The results of this study show that free physeal transplants into focal defects can remain viable and function satisfactorily if they are fashioned properly and inserted gently., Clinical Relevance: This study demonstrated that transplantation of an iliac-crest physis into a defect of the lateral aspect of the distal femoral physis can prevent bone-bridge formation, growth arrest, and the development of valgus deformity.(ABSTRACT TRUNCATED AT 400 WORDS)

The posteromedial aspect of the distal end of the femur in the area of insertion of the adductor magnus is the site of occurrence of a developmental defect that may have the roentgenographic characteristics of a malignant bone tumor. As it is asymptomatic, this common defect is almost always an incidental finding, but it has been confused with osteosarcoma. The lesion is thought to be due to trauma or the avulsion of small bits of bone at the site of insertion of the adductor magnus muscle. Histologically the lesion has been mistaken for osteosarcoma because of the immature reactive bone and fibrous tissue presnet. It is usually possible to identify these defects roentgenographically and avoid biopsy.

Core biopsy specimens of the proximal femoral growth plate from three patients with slipped capital femoral epiphysis were studied by light and electron microscopy. In the resting zone, the cartilage matrix was composed of large, densely packed collagen fibrils. The cartilage matrix in the zones of chondrocyte hypertrophy where the slippage occurred contained only scattered fine collagen fibrils in a homogeneous ground substance. The change in composition of cartilage matrix in the distal region of the epiphyseal plate may predispose that region to slippage.

Fifty six patients with angular deformities of eighty-two knees were treated with epiphyseal stapling between 1954 and 1973 and followed until maturity. There were sixty-four knock-knees and eighteen bowlegs. In twelve patients with concurrent leg-length discrepancies, long legs were stapled asymmetrically. The deformities were allowed to overcorrect before the staples were removed, but the rebound phenomenon occurred in twenty-two patients with thirty-five deformities. In older children the staples were taken out when the legs looked straight. Exaggerated physiological deformities may correct spontaneously. They should not be stapled before the skeletal age of eleven in girls and twelve in boys. Secondary deformities are corrected earlier. There were no significant complications. Ten revisions of staples were necessary because of extrusion or shifting. The results were satisfactory or improved in 87 per cent of the deformities. When it is indicated epiphyseal stapling is a safe and effective method of correcting angular deformity at the knee in growing children.

We studied the behavior of the distal femoral and proximal tibial physes after whole knee-joint replantation in skeletally immature New Zealand White Rabbits. We developed an operative model in which a rabbit's knee was isolated on a vascular pedicle and was then replanted using microvascular technique. In a short-term study (three weeks or less) of ten rabbits, the patency of the vascular repairs and the resumption of metabolic activity of the cells in the growth plates were assessed. A long-term study (ninety days) of eight rabbits was designed to monitor growth after replantation. The results indicated that in rabbits, the femoral and tibial growth plates could be removed and returned to place during whole-joint replantation. If the blood supply was successfully re-established, metabolic function of the cells in the physes remained normal during the early postoperative period, and at ninety days (near the time of skeletal maturity) bone growth in the limb that was operated on was about equal to that of the opposite limb which was not operated on.