Growth and development in replanted forelimbs

Radiographic analysis of growth in pediatric microsurgical toe-to-hand transfers

Microsurgical toe-to-hand transfers may provide improved hand function in children with absent digits. To date, documentation of the growth potential of these transferred digits has not been performed. This study reviewed the authors' series of pediatric toe-to-hand transfers, with specific attention paid to measuring growth by radiographic analysis. From 1995 to 2000, 23 toe-to-hand transfers were performed in 18 children. Age at time of transfer ranged from 2.8 to 13 years. Indications included constriction band syndrome, transverse deficiency, longitudinal deficiency, traumatic amputation, and vascular malformation. The transfers were successful in 22 of 23 procedures (96 percent success rate). Radiographic analysis of growth was performed using three criteria: (1) appearance of open epiphyseal plates, (2) comparison with preoperative radiographs, and (3) comparison with radiographs of the contralateral control toe. Epiphyseal plates remained open on postoperative radiographs in 27 of 28 phalanges (96 percent) at a mean of 12 months' follow-up (range, 1 to 36 months). The preoperative foot radiographs were compared with serial radiographs of the transferred toe over time. In 10 toe transfers with follow-up greater than 6 months (mean, 21 months), nine patients had increased bony length in the transferred digit. In four patients, radiographs of the toe transfer were compared with radiographs of the corresponding toe on the opposite foot. With a mean follow-up of 29 months, all patients had equal length measurements of the toe transfer with the contralateral toe control. These data provide objective evidence that digital growth potential is preserved in toe-to-hand transfers. Furthermore, this bone growth is comparable with that of the corresponding toe on the contralateral foot. Therefore, microsurgical toe-to-hand transfers may provide children with extra digits that maintain growth and improve hand function.

Bernard O'Brien: the microsurgical transfer of immature bone

Bernard O'Brien was one of the pioneers of vascularized epiphyseal plate transfer. His clear understanding of the wide array of potential applications for reconstructive microsurgery stimulated his interest in the transfer of growing long bones. Investigations have been carried out in his laboratory since the earliest days of skeletal free tissue transfers. This paper describes the work done with epiphyseal plate transfers in O'Brien's laboratory. Research from other centers is then reviewed. Finally, the experience with clinical application is described.

Hemiepiphyseal reconstruction using tissue donated from fetal limbs in a murine model

Epiphyseal reconstruction in the immature skeleton could have great clinical significance. Hemiepiphyseal reconstruction was performed in a murine model by transplanting fetal tissue to surgically created defects in postnatal mice. Reconstruction is facilitated by the existence of inbred strains. While the reconstruction as performed here did not completely restore the growth characteristics of the epiphysis, the model represents a potentially fruitful interface between basic and clinical biology.

Toe transfer for congenital hand defects

Toe-to-hand transfer is a well-established reconstructive option for certain congenital hand anomalies. It is the only technique which can add growth potential to the immature skeleton. Toe transfer is best suited for constriction ring amputations, which have relatively normal proximal anatomy. Transfers should be performed early in life to avoid lack of cortical integration of the new part. Anatomic variations of both hand and foot are often encountered, which influence both operative approach and functional prognosis. Indications, techniques, and complications are reviewed.

Quantifying the effect of ischemia on epiphyseal growth in an extremity replant model

Warm ischemia (21 degrees C) of 0, 2, 4, 6, or 8 hours was produced in a modified hindlimb preparation of 35 10-week-old Lewis rats by amputation. Subsequent microvascular anastomoses of each hindlimb to a syngeneic animal was done after which fluorochrome bone labels were administered 5 minutes after operation and on day 14 after operation. Epiphyseal plate growth (that between bone labels) was analyzed histomorphometrically and statistically. Epiphyseal plate growth was found to have a linear inverse relationship to ischemia time with a correlation coefficient (r) of -0.653 and high statistical significance (p less than 0.001). Overgrowth occurred at all ischemic periods except 8 hours, and vascular pedicle patency decreased as ischemia time progressed.

Longitudinal epiphyseal growth after replantation and transplantation in children

Previous investigators have shown that epiphyses are unlikely to grow after free grafting although there have been rare reports of good and even normal growth. However, growth has usually continued whenever the epiphyseal vascular supply has been maintained by microanastomosis. Of 25 growing epiphyses in our series that were transferred, 17 by replantation and eight by free tissue transfer supported by microvascular anastomosis, over an interval varying from 27 to 81 months, average length attained was 89% of normal in elective transfer, 93% of normal in replanted digits, and 92% overall. Maximum growth attained in any digit in our series was 102% of the length of the normal contralateral digit; the minimum attained was 70%.

Warm ischemic damage to the epiphyseal growth plate: a rabbit model

Warm ischemic growth plate damage was produced in the hindlimbs of 33 New Zealand white rabbits, who were 7 weeks old, by isolating the knee joint on a popliteal vascular pedicle. Zero, 3, 7, and 12 hours of warm ischemia were produced by pedicle occlusion. The 0- and 3-hour ischemic groups showed mild growth disturbances related to the surgical model and were not statistically different at 90 days postoperatively. The 7- and 12-hour ischemia groups showed severe growth disturbances and were statistically different from the 0- and 3-hour groups at all periods measured (p less than 0.05). Large central growth plate lesions were apparent by histologic examination. Twelve hours of ischemia produced a histologic picture identical to growth plate infarction. Increased warm ischemic time correlated with more severe growth retardation and evidence of increased damage to the central area of the growth plate histologically.

Experimental free vascularized epiphyseal transplants

Growth plates have been transferred both clinically and in experimental models since the end of the 19th century. Results have been unpredictable and frequently unsatisfactory due to postoperative ischemia. Modern microvascular techniques have minimized this problem and preservation of growth plate structure and function has been reported after replantation and free tissue transfers in children and immature animals. Experimental revascularized growth plate transplants were first reported in 1979. Viable orthotopic transfers are associated with rapid bony union, maintenance of radiological structure, and continued growth in length at near normal rates. Detailed studies have demonstrated a continuation of cell division, metabolic activities, and normal histology. Technetium bone scans have been a useful postoperative indicator of viability, and ischemic times of more than three hours can be tolerated. The behavior of heterotopic transplants has not yet been fully studied. Early attempts suggest that biomechanical problems may be troublesome.

Long-term utility of replanted arms

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