Failure of Formation of Parts: Transverse Arrest (Continued)


In determining treatment for the cleft hand, existing function must be considered. The two opposing digital units are often stable, mobile, and quite functional, although not cosmetically attractive. If function (including prehension with sensation) is adequate, the appearance of the hand is of secondary importance and surgical reconstruction to improve function and appearance is not always indicated. Closure of the cleft includes reconstruction of the deep transverse metacarpal ligament. Rotational osteotomies help correct rotatory deformity of adjacent fingers. The function of a monodigital hand can be improved with rotational osteotomy, opponensplasty, use of a simple opposition post, or a combination of all three.


Intersegmental Deficiency (Phocomelia). The most profound longitudinal arrest is phocomelia (see Plate 4-49), a failure of proximodistal development. Phocomelia may be total (the hand or foot is attached directly to the trunk) or partial (the hand or foot is attached to a deficient, severely shortened limb).


The patient with bilateral upper limb phocomelia is unable to position the hands for feeding and toilet activities. Frequently, the problem is further compounded by associated deformities of the lower limbs that prevent good foot prehension.


The joints in phocomelia are usually unstable and hyperextensible because of ligament laxity, and muscle power is decreased. Digits may be missing or have motor deficits. As a rule, patients require a nonstandard prosthesis with external power. Many patients can use the affected limb to control the terminal device or elbow lock in a nonstandard prosthesis, which must be kept as simple as possible to be accepted by the patient.


Patients with total upper limb phocomelia are trained to use the lower limbs for many functions and are fitted with a shoulder disarticulation prosthesis or a myoelectric arm. In partial phocomelia, treatment may not be necessary, or one of the following alternatives may be indicated: clavicular transfer to replace the missing humerus, use of a nonstandard shoulder disarticulation prosthesis, hand reconstruction to improve grip or pinch, or therapy to improve function with the existing structures.


In total lower limb phocomelia, the foot articulates with the pelvis. Treatment in the young child is a nonstandard hip disarticulation prosthesis with a fenestration for the foot, a Canadian hip joint held in place with shoulder straps, and a SACH foot without a knee hinge. The hinge is added when the child is older.


In proximal lower limb phocomelia, the ligaments are extremely lax and the tibia slides up and down in the pelvis. Motor power in the upper limb is often deficient.


In distal lower limb phocomelia, the foot articulates with the distal femur and is often monodigital. The pelvic joint is unstable.


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Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Failure of Formation of Parts: Transverse Arrest (Continued)
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