Angular Malunion. Supracondylar fractures of the humerus are quite unstable, and reduction is difficult to maintain. Even an acceptable reduction may be lost, and the bone typically heals with a resulting varus deformity. The normal carrying angle of the elbow (5 to 20 degrees) is decreased or reversed. Despite the abnormal appearance of the elbow, function may not be compromised, even with a severe deformity. Closed reduction and percutaneous pinning, or even open reduction and pinning, of these unstable fractures is used to prevent or decrease the chances of deformity. Angular malunions that result in a significant loss of function or cosmetic deformity are best treated with a corrective osteotomy at the site of the original fracture. The alignment of the corrective osteotomy is maintained with a plate and screws or an intramedullary nail. The osteotomy is often supplemented with cancellous bone grafts to ensure healing.
Rotational Malunion. This complication can occur with fracture of any long bone and is very difficult to recognize on standard radiographs. After every fracture reduction, a clinical examination is essential to ascertain that there is no residual rotational malalignment. This is most easily accomplished by comparing the rotational alignment in the injured limb to that of the uninjured limb. Rotational malunions are common in spiral fractures of the second, third, or fourth metacarpal. Residual malalignment is frequently missed because the deformity can be detected only when the fingers are flexed. On flexion of the metacarpophalangeal joints, all four digits should point toward the scaphoid on the radial aspect of the wrist.
Change in Limb Length. Shortening of the limb is a particularly common complication of fractures of long bones, especially if the fracture is significantly displaced or comminuted. Loss of structural support of the skeleton allows the muscles to contract, causing the bone to overlap and the limb to shorten. Whereas shortening of long bones after a fracture was a more common occurrence in years past, the popularization of interlocking intramedullary nails has significantly decreased the rate of this complication. Moderate shortening of the upper limb does not significantly limit function, and mild shortening in the lower limb is usually well tolerated. A leg-length discrepancy greater than ½ inch, however, often results in a limp. Simple shoe lifts compensate for leg-length discrepancies between ½ inch and 1 inch, but discrepancies greater than 1 inch usually necessitate surgical treatment. Because the majority of fractures at risk for limb shortening are likely to undergo surgical fixation in the first place, the best way to avoid a limb-length inequality is simply achieving an anatomic reduction and comparing the injured limb length to the unaffected limb at the time of initial surgery.
If limb shortening occurs in a growing child, growth of the longer limb should be arrested with fusion of the growth plate (epiphysiodesis) at the appropriate time, as determined with standardized growth charts. In a young child, a leg-length discrepancy of up to 1 inch can be corrected with epiphyseal arrest. In adults, the longer femur is usually shortened with osteotomy. Although lengthening the shortened femur is also a possibility, this procedure carries a high risk of neurovascular complications owing to stretching of soft tissues, nerves, and vessels at the time of acute bone lengthening. If the decision is made to shorten the longer femur, an appropriately sized segment of the femoral shaft is removed by way of an open osteotomy and the two major fragments of the femoral shaft are reduced and held in anatomic alignment over an interlocking intramedullary nail.
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