Coxa breva and coxa vara deformities with good femoral head to acetabulum alignment are best corrected with lengthening of the neck. Valgus osteotomy to correct the varus rotates the head in the acetabulum and further shortens the abductor lever arm.
Morscher neck lengthening
Morscher’s technique involves osteotomy and distal transfer of the greater trochanter (GT) that adds length to the superior aspect of the neck and intertrochanteric osteotomy at the bottom of the neck and lateral translation of the shaft adding length to the bottom of the neck. The three resultant fragments are fixed with plate and screws. This technique is simpler and adds length to the lower extremity. Disadvantages are 1. Length at the bottom of the neck is not necessary. 2. intertrochanteric osteotomy requires a plate to fix it. 3. GT osteotomy can injury the blood supply to the head though reported incidence of AVN is low 4.The superior aspect of the neck can continue to impinge. I do not have an indication for this osteotomy.
Relative Neck lengthening
Relative neck lengthening corrects the extra articular deformity by adding functional length to the neck, creating a thinner neck to relieve impingement, and transfer the greater trochanter to improve abductor lever arm and resting length. All this is accomplished without an osteotomy between the shaft and neck, hence no need for plate fixation. 2 screws to fix the transferred GT are the only implants. Disadvantages are 1. Need experience with development of the extended retinacular flap 2. Does not lengthen a short limb. 3. Widens the pelvis
Technique
After performing surgical dislocation approach and trochanteric flip osteotomy, bone from the greater trochanter lying above the proposed superior neck level can be removed carefully while preserving the posterior and lateral retinacular flap. All bone proximal to greater trochanter growth plate can be removed while peeling off all the soft tissues from it. Maintain the soft tissues as one flap as it contains the lateral epiphyseal vessels. For RNL, both anterior and posterior flaps are elevated only to the extent necessary to remove the GT and top of the neck. Need not go to the lesser trochanter. The greater trochanter is fixed to the lateral aspect of the newly developed neck with appropriate tension of the gluteus medius.
Wagner neck lengthening and angulation osteotomy
Coxa Vara and Breva with Caput Valgum and foveal impingement need true or relative neck lengthening to allow the additional varus peritrochanteric osteotomy to rotate the head medially in the acetabulum
Identical bilateral Caput valgum, coxa vara, coxa breva corrected on the right side with relative neck lengthening and Varus osteotomy.
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All neck lengthening techniques destroy GT growth plate and stop further growth.