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Biomedical subjects

J E Herzenberg

Publications and source records attributed to J E Herzenberg.

At least 19 recordsLinked to original sources
PubMed2000

The adaptation of perimuscular connective tissue during distraction osteogenesis.

It is not known whether the decreased range of motion observed during distraction osteogenesis results from the lack of adaptation of muscle or from fibrosis in the perimysium. The adaptation of the perimysium in the tibialis anterior muscle in skeletally immature rabbits using two distraction regimens (0.7 and 1.4 mm/day with 15% lengthening) was characterized. The resulting data indicate that during distraction osteogenesis, the muscle adapts by reorganization of its connective tissue. At a lengthening rate of 1.4 mm/day, there is perimysial fibrosis without major cellular pathologic abnormalities in the muscle fibers. The increase in perimysial thickness is characterized by an increase of collagen Type I. In addition, collagen Type I is deposited around the endomysium. The increase in total collagen and its cross-linking are dependent on the lengthening rate. The faster lengthening rate also leads to a significant decreased passive plantar flexion. Supplemental growth of the tibia was not observed, and a lack of adaptation in the muscle (based on resting length) was not seen. Together, the data suggest that decreased range of motion during distraction osteogenesis may be a function of the adaptation of the perimysium rather than of the muscle fibers.

Adaptation, Physiological↗
PubMed2000

Multiplier method for predicting limb-length discrepancy.

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.

Adolescent↗
PubMed1999

Muscle regeneration and fiber-type transformation during distraction osteogenesis.

The successful outcome of distraction osteogenesis depends in part on the adequate adaptation of the surrounding soft tissue. We characterized the adaptation of the tibialis anterior during distraction osteogenesis at different rates (0.7 and 1.4 mm/day) and amounts (15 and 30%) of lengthening. We documented the increased expression of neonatal and slow myosin heavy chain in the tibialis anterior of skeletally immature rabbits. There was neither expression of neonatal myosin heavy chain in the experimental soleus or in the slow muscle fibers of the tibialis anterior nor increased expression of slow myosin heavy chain in the soleus or gastrocnemius. The increased amount of neonatal myosin heavy chain was concentrated in the distal half of the muscle, whereas the increase in the number of fibers that were labeled with antibodies to slow myosin occurred to the same extent throughout the tibialis anterior. Electrophysiological methods showed that the tibialis anterior was functionally intact during and after distraction osteogenesis. We concluded that in the tibialis anterior of young, skeletally immature animals, distraction osteogenesis seems to induce a recapitulation of the developmental process without leading to functional changes. In addition, during distraction osteogenesis, a fiber-type transformation occurs similar to that observed in models of muscle overloading.

Animals↗
PubMed1999

Improvement in gait parameters after lengthening for the treatment of limb-length discrepancy.

BACKGROUND: Patients who have limb-length discrepancy demonstrate an altered gait pattern or a limp. The purpose of this prospective study was to compare the objective gait parameters for the shorter lower limb with those for the longer lower limb before and after lengthening and to compare these data with those for a group of twenty subjects who had no limb-length discrepancy. METHODS: Eighteen patients had equalization of limb length to within one centimeter. We analyzed the stance time, the second peak of the vertical ground-reaction-force vector, and the rate of loading with use of two force-plates arranged in a series. RESULTS: The difference in the mean stance times between the shorter and longer limbs before lengthening was 12 percent, whereas that after lengthening was 2.4 percent; the difference between the values before and after lengthening was significant (p<0.001). The difference in the stance times between the limbs of the patients who did not have limb-length discrepancy was 2 percent. Preoperatively, the mean second peak was 104 percent of body weight for the shorter limb compared with 116 percent for the longer limb; this difference was significant (p<0.001). After lengthening, the mean second peak for the shorter limb increased to 113 percent of body weight. The difference in the means for the second peak before and after lengthening was significant (p<0.001). With the numbers available, no significant difference was detected in the means for the second peak between the shorter and longer limbs after lengthening (p = 0.12). CONCLUSIONS: This study shows that lengthening of the shorter limb of patients who have limb-length discrepancy can normalize symmetry of quantifiable stance parameters and eliminate a limp.

Adolescent↗
PubMed1998

Leg lengthening in children.

Leg lengthening techniques, imported from Russia and Europe, have developed during the past 10 years in North America and have matured to become an accepted method of treating leg length discrepancy. The use of these techniques for stature lengthening in dwarfism is somewhat less widespread. A review of published reports indicates a maturation in the field of leg lengthening, with more focused studies on larger cohorts of patients having the same pathology. Long-term follow-up studies are forthcoming, and there is still extensive room for basic research. Precise indications and limits for lengthening in femoral hypoplasia and fibular hemimelia are unclear, and await additional reporting. Future research needs to include outcome studies, hardware improvements, implantable lengthening devices, and a better understanding of the basic science behind lengthening of both bone and soft tissues.

Animals↗
PubMed1998

The load applied to the foot in a patellar ligament-bearing cast.

The purpose of this study was to determine whether a patellar ligament-bearing cast reduces the load applied to a foot in a cast. In a study of ten people who had no history of gait abnormalities, disease involving the motor system, or deformities of the lower extremities, we compared the load applied to the plantar aspect of a foot in a cast (as detected with F-Scan computer-monitored pedobarographic sensors) with the total load that an extremity in a cast receives relative to the ground (as detected with force-plates). Six trials were completed three times by each person. The trials consisted of walking (1) while wearing regular shoes; (2) with a patellar ligament-bearing cast on one leg; (3) with a patellar ligament-bearing cast and an overlying soft knee brace, locked in full extension, on the leg; (4) with only a below-the-knee cast on the leg; (5) with a below-the-knee cast and an overlying knee brace, locked in full extension, on the leg; and (6) with only a knee brace, locked in full extension, on the leg. The loads at peak heel-strike for all three trials were averaged and normalized to body weight. The load on the plantar aspect of the foot, as compared with the total load, was reduced a mean of 11 percent when the patellar ligament-bearing cast was worn alone, and it was reduced a mean of 26 percent when the patellar ligament-bearing cast was used with an overlying knee brace locked in full extension. This difference was significant (p = 0.007). With the numbers available, we could not detect a significant difference between the reduction in load when a patellar ligament-bearing cast was worn alone compared with that when a below-the-knee cast was worn alone or between the reduction when a below-the-knee cast was worn alone compared with that when a below-the-knee cast was used with a knee brace (p = 0.3). In conclusion, we could not demonstrate a significant reduction in the load on the foot when a patellar ligament-bearing cast was used in a traditional fashion; however, a significant (p = 0.007) reduction in load was found when a knee brace locked in full extension was worn in addition to the patellar ligament-bearing cast.

Adult↗
PubMed1997

Femoral lengthening over an intramedullary nail. A matched-case comparison with Ilizarov femoral lengthening.

Twenty-nine patients (thirty-two femora) had femoral lengthening over an intramedullary nail, with the nail and the external fixator applied concomitantly at the time of the femoral osteotomy. After gradual distraction at a rate of one millimeter per day, the nail was locked and the fixator was removed. The mean age was twenty-six years (range, ten to fifty-three years), and the mean amount of lengthening was 5.8 centimeters (range, two to thirteen centimeters). For comparison, thirty-one patients (thirty-two limbs) who had had standard Ilizarov femoral lengthening were matched with the group that had had lengthening over an intramedullary nail; the matching was performed on the basis of the amount of lengthening, the age of the patient, the etiology of the indication for lengthening, and the level of difficulty of the procedure. Lengthening over an intramedullary nail reduced the average duration of external fixation by almost one-half. The radiographic consolidation index (the number of months needed for radiographic consolidation for each centimeter of lengthening) for the limbs that had had lengthening over an intramedullary nail was reduced significantly (p < 0.001) compared with that for the matched-case group. The range of motion of the knee returned to normal a mean of 2.2 times faster in the group that had had lengthening over an intramedullary nail. There were six refractures of the distraction bone in the matched-case group. In the group that had had lengthening over an intramedullary nail, one nail and one proximal locking screw failed. The over-all rate of complications was 1.4 per cent in the group that had had lengthening over an intramedullary nail compared with 1.9 per cent in the matched-case group. With the numbers of patients available for study, we could not detect a significant difference between the groups with respect to the operative time (p = 0.124); however, the cost of treatment and the estimated blood loss were higher in the group that had had lengthening over an intramedullary nail. On the basis of clinical and radiographic criteria, there were twenty-three excellent, seven good, and two fair results in the group that had had lengthening over an intramedullary nail compared with twenty-six excellent, four good, and two fair results in the matched-case group (p = 0.37). The advantages of lengthening over an intramedullary nail include a decrease in the duration of external fixation, protection against refracture, and earlier rehabilitation.

Adult↗
PubMed1997

Mechanical evaluation of a soft cast material.

In this study, the structural and material properties of a new semi-rigid material, Scotchcast SoftCast (SCS), were compared to the properties of two rigid materials, plaster of paris (POP) and Scotchcast Plus (SCP). Cylinders and flat beams made from 4, 6, 8, and 10 layers of each casting material were tested in three-point bending and diametrical compression. Initial stiffness and yield force values of SCS casts were significantly lower than for casts of SCP and POP made of the same number of layers. Casts made from SCS may be indicated for non-rigid applications, but not where rigid immobilization is required.

Calcium Sulfate↗
PubMed1995

A review for pediatricians on limb lengthening and the Ilizarov method.

As recently as 1986, limb lengthening in children was considered by most North American orthopedic surgeons to be both dangerous and impractical. Previous attempts were plagued by unacceptably high rates of serious complications such as nerve palsy, deep infection, malunion, broken hardware, and stiff joints. With the recent introduction of the Russian Ilizarov method and apparatus for limb lengthening, a tremendous groundswell of interest has risen. Despite a steep learning curve, many Western centers have now reproduced Ilizarov's clinical results. The important advances over prior methods are partly biologic and partly hardware related. Ilizarov's principles require a minimally invasive, low-energy osteotomy, stable external fixation, a latency period before commencing distraction, and gradual lengthening of 1 mm/d in divided doses (0.25 mm four times per day). The article reviews the background of this new technique and provides an update on results reported over the past year. There is disagreement regarding precise indications for limb salvage (lengthening) of congenital limb deficiencies versus amputation. The role of extended lengthening in dwarfism also remains controversial.

Bone Lengthening↗
PubMed1995

Compartment syndrome of the foot in children.

Compartment syndrome of the foot following trauma is well known in adults but has not been discussed frequently in texts on pediatric trauma. In the current study, seven children and teenagers were identified as having had compartment syndrome of the foot during a five-year period. The average age at the time of the diagnosis was ten years (range, four to sixteen years). The cause of the compartment syndrome was a crush injury in six patients and a motor-vehicle accident in one. All patients had swelling and pain with passive motion, but none had neurovascular deficits. Only the two oldest children had an osseous injury that necessitated open reduction and internal fixation, but all had elevated compartment pressures ranging from thirty-eight to fifty-five millimeters of mercury (5.07 to 7.33 kilopascals). All seven patients had fasciotomies of the nine compartments of the foot, and the skin was closed primarily within five days after the operation. No patient had complications or needed a skin graft. All patients had a good or excellent result after an average duration of follow-up of forty-one months (range, twenty-three to fifty-three months). Orthopaedists managing children who have a traumatic injury of the foot, especially a crush injury, should have a high index of suspicion for compartment syndrome, even in the absence of severe fracture.

Adolescent↗
PubMed1995

Safety and image artifact of external fixators and magnetic resonance imaging.

External fixators commonly used in orthopaedic trauma and reconstruction may pose a potential safety hazard to patients exposed to magnetic resonance imaging. This interaction with the scanner depends on fixator composition, magnetism, and geometry. Image artifact produced by devices during scanning may diminish the diagnostic quality of the image. A mail survey of 91 radiologists' and 167 radiological technologists' current practices identified an absence of consensus regarding protocols for scanning patients who had external fixators in place. Eighteen external fixators were tested. Force was measured during exposure to the magnetic field at 30 cm from the magnetic resonance imaging portal, at the portal, and 30 cm inside the portal. The recordings ranged from 0 to 2.2 kg. Three fixators did not generate measurable forces and therefore are considered safe for the magnetic resonance imaging based on previously published safety standards. Ten devices did not produce measurable forces until placed at the portal, indicating that these fixators may be considered safe, providing the scanned area is distant to the fixator. To investigate image artifact, the fixators were placed on a phantom model and scanned. There was substantial variation among the fixators and image quality produced, depending on fixator composition and geometry.

Artifacts↗
PubMed1994

Deformity planning for frontal and sagittal plane corrective osteotomies.

The authors have developed a universal system of geometric deformity planning based on the mechanical or anatomic axes. The place where the axes intersect is the center of rotation angulation (CORA) of a deformity. Osteotomy level and type should be considered relative to the CORA to avoid creating secondary deformities. This type of planning is applicable to both frontal and sagittal plane deformities.

Bone Malalignment↗
PubMed1994

New concepts in high tibial osteotomy for medial compartment osteoarthritis.

Medial compartment osteoarthritis remains a clinical challenge for the orthopedic surgeon. Accurate preoperative planning is an integral part of management. MCOA with genu varum is not a single condition but a family of related deformities. One single technique may not be appropriate for all the permutations. An individualized approach is necessary to address the many facets of this complex disorder. Treatment must begin with recognition of all of these facets through careful history and physical examination and radiographic evaluation and through preoperative planning of the location of the deformity (femur, tibia, or knee joint), level of angulation, magnitude of the deformity, and plane of the angulation. One can then formulate a treatment plan to address the problems identified. Surgeons should not become rigid in their choice of method or device, but also consider its appropriateness to address the problems to be corrected. Because the patient seeks to prolong the life of the knee before joint replacement, a comprehensive approach achieving as accurate a correction as possible should be associated with the best possible outcome. In total knee replacement, the important emphasis has been on achieving correct bony alignment and soft-tissue balance. With osteotomy, the emphasis has been on bony alignment. However, soft-tissue balance should also be considered an important element in preserving the knee in osteotomy surgery.

Bone Malalignment↗
PubMed1994

New procedures for tightening knee collateral ligaments in conjunction with knee realignment osteotomy.

Collateral ligament laxity has recently been recognized as an important component of frontal plane malalignment. The authors have developed new surgical techniques to re-tension lax collateral ligaments. Twenty-three collateral ligament re-tensioning with bony alignment were carried out in 17 patients, with 19 knees being graded excellent, 2 fair, and 2 poor. Recurrence of significant laxity was noted in one patient.

Adolescent↗