Rotational And Angular Deformities Of The Lower Extremities And Their Effect On Prosthetic Fitting And Gait

J. Leonard Goldner, M.D.


Rotational and angular deformities are seen more frequently in the child with congenital amputation than in the child with traumatic amputation. Variations of rotation in both groups, however, must be given careful consideration before prosthetic fitting is done and while gait difficulties are being analyzed.

In the normal child, the lower extremities show wide variation in rotation at the hip and the knee, compatible with good function but not always acceptable cosmetically. The normal hip may have 80 or 90 degree internal rotation and only 10 or 15 degree external rotation, with a resulting toe-in gait without functional difficulty. This degree of motion may be due to ante-version located in the upper end of the femur as well as capsular and soft tissue contracture aggravated by sleep or sitting posture in the young child. Fundamentally, the deformity appears to be in the skeleton in those children who do not show spontaneous improvement with development.

A comparable, but opposite, variation is seen with excessive external rotation of the hip joints. Children with this situation sit with the extremities externally rotated and walk with the toes pointing outward. Passively, the femur may be externally rotated through 60 or 70 degrees and internally rotated only 10 degrees. There is usually no functional disability. The cause of the "deformity" in either excessive internal rotation or excessive external rotation at the hip joint appears to be a combination of skeletal as well as soft tissue change. But another group of children having a tendency to excessive internal rotation or external rotation usually show relaxed joints and hyperelastic skin and their gait is dependent on the position that allows them the most stability. Many congenital amputees may be placed in this category.

Specific Treatment

Treatment of the rotary condition in the "normal child" depends upon the age, the severity, the general tissue make-up, and observed progression or improvement with growth and development. Specific treatment for excessive internal rotation of the hips in the "normal child" may begin with the modified Denis-Browne splint attached to shoes in order to control sleep posture, manual stretching which is of questionable value and, finally, time. If noticeable improvement does not occur during the first several months of treatment, elastic twisters with a waist band may be used. These will hold the extremities in the position desired but, when the twisters are removed, even after several months of use, the extremity may either swing back to the original internal rotation position or to the external position.

It is not possible to determine whether twisters are of actual value, or whether this improvement would have taken place with growth and development. More recently, external rotators, flexible upright braces attached to the heel of the shoe through a channel and around the waist to a pelvic band, have been used in the child over four or five years of age. Some children have shown considerable improvement in their gait, although there has been little noticeable change in the amount of passive rotation of the hip joints. A satisfactory controlled study utilizing all of this apparatus is not yet available.

Excessive Rotations

A small percentage of children with rotary deformity reach adolescence or adulthood with persistent excessive internal or external rotations of the hip joints The complaint is usually on a cosmetic basis, since the condition is not associated with pain or limitation of function. There is no proof that the rotary deformity is associated with early development of degenerative arthritis of the hip joints, although this possibility does exist.

Rotational osteotomy at the upper or lower end of the femur is an acceptable method of treatment and has been done occasionally when the toe-in gait is almost 90 degrees and associated with gait difficulty. Satisfactory improvement has been noted following osteotomy, but this treatment in an otherwise normal extremity is not selected with eagerness and has usually been discouraged.

The amount of internal or external rotation of the tibia on the femur varies considerably in the normal child. The loose-jointed child may show 70 or 80 degrees internal rotation with only a few degrees of external rotation, or external rotation may be possible through 30 or 40 degrees with the same amount of internal rotation. The range of motion at the knee joint is easily determined with the knee joint flexed, and the amount of internal or external skeletal tibial torsion may be determined with the knee in extension. The rotary deformity, whether it be joint or skeletal in origin, does affect the gait. Treatment may follow the same pattern as for excessive rotation at the hip joint. Rotational osteotomy may be the final solution for true osseous torsion or uncontrolled joint motion.

These basic considerations of hip and knee rotation are applicable to the lower extremities of the juvenile amputee. The longer the amputation stump the more noticeable is the rotational deformity. Excessive internal rotation at the knee joint in a child with a Symes amputation or partial absence of the foot is readily seen when a prosthesis is applied. The added weight of the prosthesis swings the tibia inward and the child usually walks with a toe-in gait.

The degree of rotation noted with the knee flexed should be carefully considered by the prosthetist at the time of the initial measurement. The tibia should be allowed to roll inward or outward, whichever the case may be, before the final position of the foot is determined. If excessive internal rotation at the knee joint is present and the foot is lined up with the tibia in external rotation, the child will assume an internal rotation gait as soon as the prosthesis is applied. Accordingly, the tibia should be internally rotated and the alignment of the foot determined while the tibia is being stabilized inwardly. If true tibial torsion exists or if the relaxation of the knee joint is such that positional alignment of the prosthesis will not control the knee joint, then a rotary osteotomy may be necessary.

First Case Report

Fig. 1a shows a 16-month-old child with congenital amputation at the knee level on the right and generalized relaxation of all joints. The initial prosthesis was made without a knee joint and was aligned with the femoral condyles in a plane parallel with the examining table. With the limb in place, the child walked satisfactorily, but the prosthesis turned inward almost 90 degrees. Various adjustments were made with pelvic straps but these were not sufficient to maintain the foot in the desired alignment. With the prosthesis off, it was evident that the child had excessive internal rotation of the hip joint, which was not taken into consideration when the original socket was measured.

The next socket will be made with the femur and thigh internally rotated and the SACH foot will be aligned accordingly. Note the left lower extremity with the external elastic twisters and the patella pointed outward about 15 degrees (Fig. 1a ). This represents maximum external rotation at the knee joint. When the child walks, the tibia turns inward about 60 degrees, with only partial correction by the twister (Fig. 1b ). This left lower extremity will probably require osteotomy at a later date if our past experience applies to this child also. Several children in our group with below-knee amputations have had a rotational problem which can b etraced to the knee joint. This has usually been managed satisfactorily by careful alignment of the foot in the external rotation position when the tibia is turned inward.

Second Case Report

Fig. 2a depicts an 18-month-old child with congenital amputation and a knee flexion contracture of 45 degrees, and valgus of the tibia at the knee joint of 20 degrees, associated with tibial epiphyseal dysplasia. This child showed excessive internal rotation at the hip and no unusual rotation at the knee joint. The initial prosthesis (Fig. 2b ) was satisfactory for two years, although internal rotation at the hip gave increasing difficulty in walking. The child could voluntarily externally rotate the extremity as noted in this picture, but could not control internal rotation while walking. Fig. 2c depicts the degree of knee flexion which initially was tolerated quite well.

The child was observed recently and had developed a gait with full 90 degree internal rotation at the hip and even more valgus at the knee. The combination of internal rotation at the hip and valgus and flexion at the knee made the apparent valgus almost 45 degrees, since the 45 degree flexion deformity of the knee was acting as valgus on weight hearing Her gait was awkward, she was toeing-in almost 90 degrees and the cause of the difficulty was a combination of hip and knee trouble.

Fig. 3 a shows the flexion and valgus deformity and the epiphyseal displasia. Fig. 3 b shows the extremity in plaster posoperatively, following osteotomy in the lower area of the femur done for correction of flexion, valgus and rotation (paient of Dr. Frank Clippinger). The entire femur was internally rotated and held inward by the Kirschner wire through the femoral shaft. Following osteotomy, the lower segment was turned outward almost 90 degrees, and the distal segment was angulated anteriorly about 40 degrees and medially about 20 degrees.

A new prosthesis has not yet been fabricated, but I will provide follow-up information in a future issue of the Inter-Clinic Information Bulletin.

Summary

The range of hip and knee joint motion must be determined and recorded prior to prosthetic fitting and gait training. Angular and rotational deviations can be corrected by triplane osteotomy in certain situations.

Dr. Goldner is Professor of Orthopaedic Surgery Duke University School of Medicine Durham, North Carolina