Congenital abnormalities of the lower extremity. PFFD - proximal focal femoral deficiency. CTP - congenital tibial pseudarthrosis
The book lists a number of lower limb congenital deformities not in the question, but let's do them anyway.
Hammer toe (mallet toe)
This is a flexion deformity of the proximal interphalangeal joint of the second toe, with extension of the distal interphalangeal joint. It is genetic and can lead to problems at the tip of the toe due to increased pressure.
Treatment is generally nonoperative with shoes that have high toe boxes or foam or silicone gel sleeves.
Claw toe
Characterised by metatarsophalangeal hyperextension, with proximal and distal interphalangeal joint flexion. MTP hyperextension is the primary pathology, it chases unopposed flexion of the DIP and PIP by the flexor digitorum longus. This is commonly caused by synovitis, trauma or missed compartment syndrome. It is also of cause associated with certain congenital abnormalities such as neuromuscular diseases which affect intrinsic and extrinsic muscle balance. Treatment is taping and shoe modification.
Mallet toe
This is hyperextension of the distal interphalangeal joint, caused by a contraction of the flexor digitorum longer, often due to pressure of toe against the ned of the shoe (in acquired cases) or in congenital cases due to flexion and lateral deviation of the distal interphalangeal joint. Treatment is shoes with high toe boxes and silicone toe sleeves (as with hammer toe).
Proximal femoral focal deficiency
This is a congenital defect of the proximal femur in which part of the bone is missing, it is can manifest in different ways including:
- Absent hip
- Femoral neck pseudoarthrosis
- Absent femur
- Shortened femur
This disease is the result of failure in primary ossification, it is rare and sporadic in etiology, and is associated with sonic hedge-hog gene. The most common manifestation is that of partial skeleton defect in the proximal part with a variably unstable hip joint and shortening.
The diseases are classified into A, B, C and D, based on the presence or absence of the femoral head and the extent of acetabular dysplasia (see table). The physical presentation is the severe shortening of one or both legs, with a short bulky thigh that is flex, abducted and externally rotated. The feet are generally spared.
The goals of treatment are dependent on the extent of leg length discrepancy, the presence of foot deformities, the adequacy of musculature and proximal joint stability.
Treatment options include:
- Non operative
- Observation (indicated in bilateral cases)
- Extension prosthesis
- Operative
- Ambulation without prosthesis (limb lengthening)