Purpose of the study: Spasticity of the rectus femoris (RF) in cerebral palsy patients is considered to be the main cause of stiff knee gait. The kinematics of this muscle, variations in length and speed of lengthening, are altered. Research is however lacking on changes in this parameter after surgery. Our objective was to study its effect on the quality of gait and on the kinematics of the RF in order to identify kinetic behaviour with diagnostic value.

Material and methods: Twenty-six transfers were performed during multiple level interventions. A uniform technique was applied: wide separation of the RF from the vastus muscles and supra-patellar tenotomy, suture of the RF tendon to the gracilis tendon tunnelled through the medial intermuscular partition. Intramuscular lengthening of the hamstrings (n=20) was associated with patella lowering procedures (n=4). The Gait-Deviation-Index (GDI) and the Goldberg score were determined pre- and postoperatively to quantify gait quality and search for stiff knee. A musculoskeletal model (virtual RF) was developed to simulate the trajectory of the RF during gait.

Results: The quality of gait improved (+18±12 GDI) with a negative interaction between the preoperative GDI and its improvement. For the Goldberg score, surgery yielded 88% improvement. Surgery had a significant effect on normalising the timing of RF lengthening and the maximal lengthening speed. Improvement in stiff knee was correlated with a normalisation of the timing of maximal length.

Discussion: Improvement in gait quality was greater when the preoperative quality is low; there is a risk of no improvement if the GDI is > 75. Normalisation of the timing of the maximal length of the RF is correlated with improvement in knee oscillation. Early timing signals a postoperative improvement in stiff knee. Early peak in the speed of lengthening of the RF can be explained by early triggering of spasticity during weight bearing which would limit the lengthening of the RF.

Conclusion: Global improvement of gait quality and stiff knee has been demonstrated. Certain muscular kinematic parameters are normalised, demonstrating the effect of transfer during oscillation but also during weight-bearing. Early peak in RF lengthening is a prognostic factor of successful surgery.

Purpose of the study: Variations in patellar height in relation to the trochlea and the joint line can be a cause of pain and instability and limit the range of knee flexion. The Caton and Deschamps index (CDI) was described and validated in a cohort of adult subjects. The purpose of this work was to validate this index and set the reference values in a paediatric population.

Material and methods: Lateral view of the knee were obtained in 300 patients who consulted for minor trauma without ligament or bone injury. Thirty patients, aged 6 to 15 years, were included in each age group (1-year groups). All radiographs were qualified as normal by the radiologist. Two series of measures were made in random order and at an interval of 8 days by two independent observers. The patellar height and the length of the patellar tendon were measured with computer assistance. The interob-server and intraobserver variabilities were determined.

Results: The mean patellar height was 33.39±7.40 mm. The mean length of the patellar tendon was 34.57±67.36 mm. The mean CDI was 1.06±0.21. There was not significant correlation between patient age, height of the patella and length of the patellar tendon. Thus the height of the patella and the length of the patellar tendon increased with age while the CDI was statistically lower in older patients. The height of the patella was identical in the two genders while the patellar tendon was statistically longer in boys. The CDI was statistically higher in boys. Interobserver and intraobserver agreement was excellent.

Discussion: CDI is a simple and reproducible measurement in adults and in children and adolescents. During growth, it is an alternative to the Insall index which has limited reproducibility and the Koshino index which is difficult to use in routine clinical situations. We found a correlation between CDI and children’s age, related to progressive ossification of the patella.

Conclusion: The CDI is a tool which can be used in routine practice to study patellofemoral problems in the paediatric population as long as the physiological values are weighted by age.

Introduction: The aim of the study is to assess the complication rate in lengthening of the femur and to analyze the main factors inducing complications.

Materials & method: A retrospective study of 151 cases of lengthening with different methods (External Fixator of Judet 9, Callotasy with Orthofix :89, Ilizarov 9, External Fixator of Wagner 9, Lengthening Albizzia Nail 29) was investigated. The mean age was 13, 21 years (ET : 4,82, max : 38, min : 4). The aetiologies of femoral length discrepancy were congenital in 85 cases, post traumatic in 30, Post infectious in 22 and neurologic in 13 cases. One girl had Still’s Disease. The mean elongation was 55,17mm (ET : 17,3, Max ; 130, min : 20) except with the Ilizarov method with a mean lengthening of 91,8 mm. The mean percentage of elongation was 21 %

Classification of the Complications was in three grades :

- I : Benign complication without any unexpected surgery or anaesthesia

The complications were recorded in four periods: surgery, elongation, consolidation and late complications

Results: There were 151 complications (78 Grade I, 59 grade III, 14 grade III). There were only three complications during first surgical procedure, 95 during elongation 49 during consolidation and 4 late complications. Analysis of the different pathologies shows that the rate of complications is the same for each etiology (around 100%) but the rate of complications of grade 2 and 3 shows a significant difference with a higher rate for neurological and congenital aetiologies. Benign complications are found in the post infection group. Analysis of the different methods used shows the same rate of complications in benign conditions except for the Albizzia Nail with a significant lower rate. Complications of grade 2 are seen in the ancient Judet method and in the Albizzia Nail due to the multiple general anaesthesia . Complications of grade 3 are seen in the Wagner method due to a high rate of congenital pathology and to a mean lengthening of 35 % of femoral initial length.

Articular complications do not show any significant difference between the different methods. The main complications are seen in neurological and post infectious diseases. The mean percentage of lengthening in these complications is not different of the mean percentage of the series.

Conclusion: Lengthening of the femur is still a difficult problem with a mean rate of complications of 100 % The type of method used is not the main determinant in the appearance of these complications. We want to emphazise the difficulties in performing lengthenings in neurological and congenital pathologies.

We have used the Ilizarov technique for severe flexion deformity of the knee in 11 patients (13 knees) between 1986 and 1994 and have followed them up for an average of 4.1 years. The age of the patients at operation ranged from 1.7 to 18.8 years.

The femoral and tibial components were connected by two anterior hinges, medial and lateral, and two posterior distraction rods. The deformity was corrected to a femorotibial lateral shaft angle of less than 20°. A permanent orthosis was applied after removal of the fixator. Fractures occurred in four patients and paralysis of the common peroneal nerve in another. There was a recurrence of the deformity in four patients.

At the last review all patients were able to walk on their operated leg with or without an orthosis.

We have found the Ilizarov method to be helpful in correcting severe fixed flexion deformity of the knee, with relatively few complications, but the basic principles of the method must be carefully followed.