Orthopedics - Oleksa A.P. 2006

Congenital and acquired deformities of the lower limb
Congenital knee joint anomalies
Flexed knee (genu flexum)

By a "flexed knee", we understand a lower leg flexed at the knee joint, which prevents its full extension. The degree of lower leg flexion varies—from slight to an angle of 90° or more. The causes of a flexed knee include both congenital and acquired factors. In congenital deformities, Hnevkovsky and Čičak (Hnevkovsky O., 1958) proved that genu flexum is frequently accompanied by a developmental anomaly of the lower leg flexor Muscles, such as the appearance of the m. praesemimembranosus with a typical Displacement of the n. tibialis, etc.

Clinically, a taut band (pterygium) can be observed in the popliteal region when the knee is slightly bent, which prevents the extension of the lower leg. Palpation reveals a thickening of the subcutaneous longitudinal Connective Tissue band; sometimes an abnormal Skin fold (pseudopterigium) is present along the popliteal region over an aberrantly positioned tendon of one of the flexor muscles.

Among the acquired causes of a flexed knee (contracture) are rheumatoid Arthritis, spastic paralysis (Fig. 173), dense and sometimes keloid post-burn (post-traumatic) longitudinal scars in the popliteal region that involve the popliteal Tissues to varying depths. Treatment for such deformities is exclusively surgical.

In congenital flexed knee, the mispositioned Muscle is resected, and the tendons of other lower leg flexor muscles causing the flexion are lengthened. Sometimes a posterior capsulotomy of the joint is required. Following surgery, a plaster cast is applied with the knee straightened to the degree achieved effortlessly during the operation. Full extension at the knee is attained through serial redressement. After the removal of the cast, children must wear an orthopedic brace for some time to prevent the recurrence of flexion. Strengthening the quadriceps femoris muscle during the postoperative period is crucial, for which physical therapy and massage are administered.

It is extremely challenging to treat a flexed knee caused by arthromyodysplasia (Arthrogryposis). As a rule, such cases are managed conservatively with osteotomy to position the lower limb into a functionally favorable, stable alignment, along with muscle massages and physical therapy.