Purpose: The difficulty children with cerebral palsy have walking often worsens during adolescence due to permanent flexion of the hip, knee and ankle joints associated with limited active extension of the knee due to ascension of the patella and stretched patellar tendon. Surgical descent of the patella associated with release of hip flexion and sometimes lengthening of the hamstrings avoids the squatting position when walking facilitating function. The short- and mid-term efficacy of this intervention has been demonstrated. The purpose of this work was to evaluate the long-term functional outcome and its environmental dimension, that is its effect on ambulation in adult life.

Material and methods: Twenty-two subjects with cerebral palsy aged 19 to 35 years had undergone surgery at average age of 12 years. Mean postoperative follow-up was 11 years. All of the subjects were evaluated with a questionnaire used to class walking function in six levels. The current walking level (M3) was compared with the preoperative level (M1) and the level at the end of postoperative rehabilitation (M2). Functional gait categories were also assessed.

Results: Fifteen subjects progressed at least one functional category between M1 and M3. Five subjects remained at the same level from M1 to M2 and M3 but were nevertheless satisfied with the result (less knee pain, better balance in the upright position). Two subjects regressed one category between M2 and M3 after having progressed one category from M1 to M2. Twelve of the 22 subjects had functional walking capacity in their home. All of these subjects had to use a wheel chair in their home before the operation. For certain subjects, use of anti-flexion knee casts preoperatively avoided the need for hamstring lengthening.

Discussion: There have been few publications concerning this surgical procedure and its very long-term functional impact. For the majority of the subjects studied here, the functional result achieved at the end of postoperative rehabilitation was maintained in the long-term. The functional gait categories provide an easy way to assess functional outcome, even by telephone, in the subject’s personal environment.

Purpose: We searched to define a fracture index useful for predicting the risk of bone fracture in children with essential bone cysts.

Material and method: We reviewed 96 children with an essential bone cyst. The following clinical data were recorded: age, cyst localisation, circumstances of diagnosis.

The radiological analysis was based on 193 AP and lateral x-rays. We measured: 1) the distance separating the superior pole of the cyst from the suprajacent growth cartilage, 2) the largest cyst diameter, 3) the greatest cyst height, 4) the thinnest cortical width facing the cyst, 5) the cyst surface area calculated exactly using surface area software and expressed as a a ratio of shaft diameter (S/d2, Kaelin index). These different parameters were compared for cysts associated with fracture or not.

Results: Mean age at diagnosis was 10.4 years (range 2 – 12.8 years). Most of the cysts were located in the upper portion of the humerus (72%). Fracture was the inaugural sign in 68% of the cases.

Comparing the two cohorts of patients demonstrated that the following differences were significant (Student’s t test): 1) cyst width (p=0.0038): below 16 mm none of the cysts fractured. For wider cysts, there was no difference between the fracture and non-fracture cysts. 2) cortical thickness (p=0.0002); cortical thickness greater than 5 mm protected against fracture. If the cortical measured less than 3 mm, the risk of fracture was greater than 50%. 3) Kaelin index: (p< 0.0001) was directly correlated with fracture risk but no cutoff could be identified.

For an 80 – 100% risk of fracture, the cyst must have the following characteristics: width > 30 mm, height > 75 mm, cortical thickness < 2.4 mm, Kaelin index > 5.

For a 50% risk of fracture, the cyst must have the following characteristics: width > 24 mm, height > 55 mm, cortical thickness < 3 mm, Kaelin index > 3.

Conclusion: The Kaelin index is reliable but difficult to calculate in the consultation setting. Cortical thickness is a good indicator. Its predictive value can be improved by correlating the height of the cyst with its width. These measure can be obtained easily during consultation.