The effects of femoral derotation osteotomy in cerebral palsy: a kinematic and kinetic study. Veronica Cimolin1, Luigi Piccinini2, Nicola Portinaro3,4, Anna Carla ...
DOI: 10.5301/HIP.2011.8758
Hip Int 2011 ; 21 ( 06 ): 657 - 664
Original Article
The effects of femoral derotation osteotomy in cerebral palsy: a kinematic and kinetic study Veronica Cimolin 1, Luigi Piccinini 2, Nicola Portinaro 3,4, Anna Carla Turconi 2, Sonia Albonico 2, Marcello Crivellini 1, Manuela Galli 1, 5 Bioengineering Department, Politecnico di Milano, Milan - Italy Scientific Institute (IRCCS) Eugenio Medea, Bosisio Parini, Lecco - Italy 3 Department of Orthopaedics, University of Milan, Milan - Italy 4 Scientific Institute (IRCCS) Humanitas, Rozzano, Milan - Italy 5 Scientific Institute (IRCCS) “San Raffaele Pisana” - San Raffaele SpA, Rome - Italy 1 2
Abstract: We attempted to quantify the effects of isolated femoral derotation osteotomies using clinical evaluation and gait analysis (kinematics and kinetics) in patients with cerebral palsy (CP). Twelve children with CP were evaluated before and 10 months after isolated femoral derotation osteotomy, and 15 healthy children were evaluated as controls. There were significant improvements on clinical examination. A better position of the hip and ankle in the transverse plane was evident and significant changes occurred in terms of hip and ankle kinetics after surgery. Improvements in kinematics and hip and ankle power are very important biomechanically. The correction of lever arm dysfunction and more physiological hip and ankle power generation result in an improvement in terms of energy consumption, leading to a more functional and economic gait pattern. Key words: Cerebral palsy, Gait analysis, Femoral derotation osteotomy, Kinematics, Kinetics Accepted: September 14, 2011
INTRODUCTION An internally rotated gait is common in children with Cerebral Palsy (CP) and is associated with severe functional and cosmetic gait disturbances. Rotational deformity of the hip in CP is often due to increased femoral neck anteversion. After birth anteversion rapidly decreases until the age of 4, then decreases at a slower rate and comes to a final physiologic value of approximately 15° at skeletal maturity. Femoral neck anteversion in newborns with CP is similar to anteversion in healthy children. However, anteversion in CP decreases less and remains high before and after skeletal maturity, mainly due to neuromuscular
imbalance, resulting in persistence of foetal alignment, described as femoral torsion, or medial rotation deformity of the hip (1, 2). Conservative approaches to correct this medial rotation deformity is not effective and surgical intervention remains the best choice (2, 3). Excessive femoral neck anteversion is generally corrected with femoral derotation osteotomy. Several methods have been used, in both the proximal and distal femur (2). Gait Analysis represents an important tool because it allows assessment of rotational abnormalities, and provides information in relation to abnormalities in the transverse plane (which are difficult to observe clinically) and gait
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Kinematic and kinetic effects of femoral derotation osteotomy in cerebral palsy
kinetics. Gait changes after femoral derotation osteotomy have been mainly evaluated using gait analysis (1, 3-6). However, this type of operation has been generally performed at multiple levels, and it has been difficult to evaluate the effects of a single technique. Following single level surgery, attention has focused mainly on kinematics (5) and kinetics has been neglected. We used gait analysis to quantify the effects of proximal femoral derotation osteotomy in a group of CP patients. Their gait was assessed considering distal and proximal joints, in terms of kinematics and kinetics. The patients were examined before treatment and 10 months after surgery.
MATERIALS AND METHODS Patients Twelve CP diplegic independent children (mean range: 11.7+3.4 years; 24 limbs; 6 males and 6 females) were evaluated. Selection criteria were a diagnosis of spastic diplegia, independent gait without walking devices, femoral anteversion greater than 45°, no prior orthopaedic surgery in the lower extremities, no previous injections of botulinum toxin, and age older than 8 years. Femoral anteversion was assessed according to the method described by Ruwe et al (7). Unilateral or bilateral hip dislocation or nonambulatory status were contraindications for osteotomy and such patients were excluded from the study. All patients were able to walk independently without the use of crutches, walkers or braces. A control group of 14 healthy subjects (Control Group: CG; range: 10.4+4.9 years; 7 males and 7 females) was also assessed. These individuals had no prior history of cardiovascular, neurological or musculoskeletal disorders. They exhibited normal range of motion and muscle strength, and had no apparent gait abnormalities. Parents gave their written consent to their child’s participation in this research, in accordance with the local ethical committee requirements.
Procedure All patients underwent clinical examination, video-recording and gait analysis in two sessions, the first before surgery and the second 10 months later. 658
All operations were carried out by the same team of orthopaedic surgeons and all patients had bilateral surgery. Proximal femoral derotation was conducted with the patient lying supine, using the lateral approach. A “narrow” or “small fragment” dynamic compression plate (7 or 8 hole) was used for internal fixation. Two proximal screw holes were prepared; the line of the plate was marked on the long axis of the lateral side of the femur and another line, parallel to this line, was marked along the long axis on the anterior face of the femur (90° to the plate lateral line). The osteotomy was performed perpendicular to the long axis of the femur. Proximal screws were reinserted and the distal fragment rotated externally according to the anterior marked line. Two distal screws were inserted while checking the range of rotation according to the position of the patella. If the desired correction was achieved, the remaining screws were inserted and the wound closed. A standard regime was used for rehabilitation, preventing stiffness during the period of immobilization, positioning and passive range of motion exercises. Standing and ambulation were allowed with an appropriate assistive device for a short distance from the third week after radiographs had been performed. Further range of motion exercises, strengthening and other activities were allowed according to pain and progress. At the third to fourth month, intensive therapy (2 or 3 times per week) was recommended, consisting of resistance training, cycling and swimming.
Measurements recorded During clinical examination, the gross motor function measure (GMFM) and measurement of muscle length (iliopsoas, hamstrings and rectus femoris) were recorded. The GMFM measures overall functional ability and it consists of 88 items, divided into the following sections: 1. lying and rolling; 2. sitting; 3. crawling and kneeling; 4. standing; 5. walking, running and jumping. Each section contributes to the total GMFM score (range: 0-100) (8), and the overall score has demonstrated excellent psychometric properties in children with CP. The measurement of muscle length was assessed for iliopsoas, hamstrings, adductors and rectus femoris, according to Kendall’s method (9). The iliopsoas length is the amount of hip flexion while the subject has the controlateral knee towards the chest; and normal joint excursion exhibits about 0° of hip flexion. Negative values are therefore indicative of hip flexion contracture. In the same position the rectus
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Cimolin et al
femoris length is examined. The posterior aspect of the ipsilateral thigh should touch the bed with the knee in 80° flexion position. Tightness of the rectus femoris will result in less knee flexion. Hamstrings length is measured in terms of measurement of popliteal angle while the subject is lying supine with the thigh in 90° flexion; the normal joint excursion associated with the hamstrings is about 0° of knee flexion. Adductor length is measured with the patient supine with flexed a knee. All the measures were performed using a goniometer and by two physical therapists with more than 10 years of experience in order to assure reproducibility. Gait analysis was conducted using an optoelectronic system with passive markers (ELITE2002, BTS, Milan, Italy) working at a sampling rate of 100 Hz, with passive markers positioned according to Davis (10), for kinematic of movement evaluation, two force platforms (Kistler, CH), for movement kinetic evaluation, and a synchronic video system (BTS S.p.A., Milan, Italy). After collecting of some anthropometric measures required by the specific protocol (height, weight, tibial length, distance between femoral condyles or diameter of the knee, distance between malleoli or diameter of the ankle, distance between anterior iliac spines and thickness of the pelvis), passive markers were placed at special points of reference, directly on the subject’s skin, as described by Davis (10). After a preparatory phase, the patients were asked to walk barefoot at a self-selected and convenient speed along a 10-metre walkway. At least seven trials were recorded during each session in order to ensure consistency in the assessment. Starting from the 3D coordinates of the 3 markers placed on each segment (pelvis, thigh, leg and foot) a rigid frame was computed; the Euler angles between two frames are the flex-extension, abduction-adduction and internal-external rotation of principal joints) (10). All data acquisition was performed by the same experienced operator, to assure reproducibility of the acquisition technique and to avoid the introduction of errors due to different operators. Some indices obtained from kinematic and kinetic data were analysed: spatio-temporal parameters, joint angles values at specific instant of the gait cycle and moment and power graphs; the details are reported in Table I.
Statistics The defined parameters were computed for each subject and then the mean values and standard deviation relating
to all indices were calculated for the pathological group in the two sessions and for the healthy group. Data of the first (preoperative) and the second (postoperative) session were compared with Wilcoxon’s tests, in order to detect significant changes after surgery in the pathological group. Statistical significance was set at p
