muscles and tendons
Muscles and tendons are often shorter in those with cerebral palsy than in normally developed individuals. Perhaps because of this shortness, the muscles and tendons of the cerebral palsied tend to be fairly tight. In addition, their muscles tend to lack strength and behave spastically. These physical abnormalities seem to be particularly true of joint extensors, which are those muscles and tendons located around joints that help with joint extension (for example, the hamstring), and strongly influence walking ability. Some people with cerebral palsy exhibit the co-activation of unnecessary muscles (i.e. other than the primary muscles needed to carry out a movement) during physical actions. In some cases, problems with muscles and tendons may be corrected via surgery, such as tendon lengthening and tendon transfer.
NOTE: FORMAT:
#. Title of article
Article Abstract
[citation information]
[link to abstract]
1. Distal femoral extension osteotomy and patellar tendon advancement to treat persistent crouch gait in cerebral palsy
BACKGROUND: Hallmarks of a persistent crouched walking pattern exhibited by individuals with cerebral palsy usually include loss of an adequate plantar flexion/knee extension couple, hamstring and/or psoas tightness, or contracture in conjunction with quadriceps insufficiency. Traditional treatment addresses the muscle-tightness component, but not the contracture or the muscle insufficiency. This study was performed to evaluate the effectiveness of distal femoral extension osteotomy and/or patellar tendon advancement in the treatment of crouch gait in patients with cerebral palsy. METHODS: A retrospective, nonrandomized, repeated-measures design was used. Individuals with a diagnosis of cerebral palsy were included if they had had (1) a distal femoral extension osteotomy in combination with a distal patellar tendon advancement (thirty-three patients), (2) a distal femoral extension osteotomy without patellar tendon advancement (sixteen), or (3) a distal patellar tendon advancement only (twenty-four). All subjects were evaluated with preoperative and postoperative gait analysis. Gait, radiographic, strength, and functional measures were included in the analysis to assess changes in knee function. RESULTS: Seventy-three individuals met the criteria for inclusion. A single side was chosen for the analysis of each subject. Ninety percent of the subjects had additional, concurrent surgery. Improvements were noted in the index assessing the level of gait pathology and in functional variables across all groups, and pain was consistently decreased. All preoperative stress fractures healed. Strength levels were maintained across all groups. The Koshino index of patellar height improved from 1.4 to -2.3 in the group treated with patellar tendon advancement only and from 1.5 to -2.9 in the group treated with both osteotomy and tendon advancement. The range of knee flexion improved an average of 15 degrees to 20 degrees, and stance-phase knee flexion was restored to the typical range (9 degrees to 10 degrees) in the groups that had advancement of the patellar tendon as part of the procedure. Individuals who underwent a distal femoral osteotomy only were still in a crouch (a mean of 31 degrees of knee flexion in midstance) at the final assessment. CONCLUSIONS: Inclusion of patellar tendon advancement is necessary to achieve optimal results in the surgical management of a persistent crouch gait exhibited by adolescents and young adults with cerebral palsy. When this procedure is done alone or in combination with a distal femoral extension osteotomy (for the treatment of a knee flexion contracture), knee function in gait can be restored to values within typical limits, with gains in community function.
[Stout, J. L., Gage, J. R., Schwartz, M. H. & Novacheck, T. F. (2008). Distal femoral extension osteotomy and patellar tendon advancement to treat persistent crouch gait in cerebral palsy. The Journal of Bone and Joint Surgery. American Volume, 90(11), 2470-84.]
[ Abstract ]
2. The role of estimating muscle-tendon lengths and velocities of the hamstrings in the evaluation and treatment of crouch gait
Persons with cerebral palsy frequently walk with excessive knee flexion during terminal swing and stance. This gait abnormality is often attributed to "short" or "spastic" hamstrings that restrict knee extension, and is often treated by hamstrings lengthening surgery. At present, the outcomes of these procedures are inconsistent. This study examined whether analyses of the muscle-tendon lengths and lengthening velocities of patients' hamstrings during walking may be helpful when deciding whether a candidate is likely to benefit from hamstrings surgery. One hundred and fifty-two subjects were cross-classified in a series of multi-way contingency tables based on their pre- and postoperative gait kinematics, muscle-tendon lengths, muscle-tendon velocities, and hamstrings surgeries. The lengths and velocities of the subjects' semimembranosus muscles were estimated by combining kinematic data from gait analysis with a three-dimensional computer model of the lower extremity. Log-linear analysis revealed that the subjects who walked with abnormally "short" or "slow" hamstrings preoperatively, and whose hamstrings did not operate at longer lengths or faster velocities postoperatively, were unlikely to walk with improved knee extension after treatment (p < 0.05). Subjects who did not walk with abnormally short or slow hamstrings preoperatively, and whose hamstrings did operate at longer lengths or faster velocities postoperatively, tended to exhibit unimproved or worsened anterior pelvic tilt after treatment (p < 0.05). Examination of the muscle-tendon lengths and velocities allows individuals who walk with abnormally short or slow hamstrings to be distinguished from those who do not, and thus may help to identify patients who are at risk for unsatisfactory postsurgical changes in knee extension or anterior pelvic tilt.
[Arnold, A. S., Liu, M. Q., Schwartz, M. H., Ounpuu, S. & Delp, S. L. (2006). The role of estimating muscle-tendon lengths and velocities of the hamstrings in the evaluation and treatment of crouch gait. Gait & Posture, 23(3), 273-81]
[ Abstract ]
3. Relevance of the popliteal angle to hamstring length in cerebral palsy crouch gait
The popliteal angle is a widely used clinical means of assessing hamstring length in cerebral palsy patients. The relevance of the popliteal angle as a measure of hamstring length was assessed in this prospective study. Sixteen patients with cerebral palsy with crouch gait had their conventional and modified popliteal angles measured by nine observers on two separate occasions. With use of the conventional and modified forms of the test, 74 and 70%, respectively, of the observed variability was inter-and intraobserver related. The range of SDs for each observer using the conventional test was 7.1-13.6 degrees (average 10.9 degrees ), and with use of the modified form of the test, the range was 6.3-4.2 degrees (average 10.5 degrees ). The maximum hamstring length of each subject during gait was determined by three-dimensional modelling of their lower limbs. The modified popliteal angle measurements of the most repeatable observer demonstrated an inverse relationship between modified popliteal angle and maximum hamstring length (p < 0.01) and muscle excursion (p < 0.01). Only 10 of 32 limbs had short medial hamstrings.
[Thompson, N. S., Baker, R. J., Cosgrove, A. P., Saunders, J. L. & Taylor, T. C. (2001). Relevance of the popliteal angle to hamstring length in cerebral palsy crouch gait. Journal of Pediatric Orthopedics, 21(3), 383-7.]
[ Abstract ]
4. Hamstrings in cerebral palsy crouch gait
After observing patients with increased anterior pelvic tilt following medial hamstring lengthening in cerebral palsy crouch gait, we became concerned that the hamstrings may be functionally important hip extensors. To evaluate this, we studied the three-dimensional motion of the hip and knee, calculated hamstring muscle length, and evaluated dynamic electromyography (EMG) of the medial hamstrings in 16 patients with diplegic cerebral palsy and crouch gait to determine if the hamstrings were extending the hip. Twelve of 16 patients exhibited marked prolongation of electrical activity in the medial hamstrings, and in eight of these 12, the hamstrings were contracting concentrically, thus aiding in hip extension during gait. Hamstrings may be important hip extensors in some cerebral palsy patients with crouch gait; however, other deformities contributing to crouch (such as hip flexion contracture) need to be considered before isolated hamstring lengthening is performed in these patients.
[Hoffinger, S. A., Rab, G. T. & Abou-Ghaida, H. (1993). Hamstrings in cerebral palsy crouch gait. Journal of Pediatric Orthopedics, 13(6), 722-6.]
[ Abstract ]
5. Crouched postures reduce the capacity of muscles to extend the hip and knee during the single-limb stance phase of gait
Many children with cerebral palsy walk in a crouch gait that progressively worsens over time, decreasing walking efficiency and leading to joint degeneration. This study examined the effect of crouched postures on the capacity of muscles to extend the hip and knee joints and the joint flexions induced by gravity during the single-limb stance phase of gait. We first characterized representative mild, moderate, and severe crouch gait kinematics based on a large group of subjects with cerebral palsy (N=316). We then used a three-dimensional model of the musculoskeletal system and its associated equations of motion to determine the effect of these crouched gait postures on (1) the capacity of individual muscles to extend the hip and knee joints, which we defined as the angular accelerations of the joints, towards extension, that resulted from applying a 1N muscle force to the model, and (2) the angular acceleration of the joints induced by gravity. Our analysis showed that the capacities of almost all the major hip and knee extensors were markedly reduced in a crouched gait posture, with the exception of the hamstrings muscle group, whose extension capacity was maintained in a crouched posture. Crouch gait also increased the flexion accelerations induced by gravity at the hip and knee throughout single-limb stance. These findings help explain the increased energy requirements and progressive nature of crouch gait in patients with cerebral palsy.
[Hicks, J. L., Schwartz, M. H., Arnold, A. S. & Delp, S. L. (2008). Crouched postures reduce the capacity of muscles to extend the hip and knee during the single-limb stance phase of gait. Journal of Biomechanics, 41(5), 960-7.]
[ Abstract ]
6. Quantitative and qualitative functional evaluation of upper extremity tendon transfers in spastic hemiplegia caused by cerebral palsy
BACKGROUND: The purpose of this study was to determine if upper extremity function and joint positioning improved after tendon transfer surgery in patients with spastic hemiplegia caused by cerebral palsy. METHODS: Thirteen patients with spastic hemiplegia underwent tendon transfer surgery at a mean age of 10.8 years (range, 7-24 years). Before surgery, all patients were evaluated with a standardized motion laboratory analysis protocol. At a mean follow-up of 3.6 years (range, 1-10 years), 13 patients returned for a repeat motion laboratory analysis using the same protocol. The motion laboratory studies were then compared quantitatively, comparing times for completion of the Jebsen-Taylor hand test, and qualitatively for elbow, forearm, wrist, finger, and thumb positions using the validated Shriner's Hospital Upper Extremity Evaluation protocol. RESULTS: In timed testing on the Jebsen-Taylor hand function test, 5 patients improved, 5 patients remained the same, and 3 patients worsened. No statistically significant change in timed testing was noted for any of the 6 subtests. A qualitative assessment of limb position during completion of tasks showed a significant improvement in position for the elbow (P < 0.01), forearm (P < 0.02), wrist (P < 0.02), and fingers (P < 0.02). There was no significant change in thumb position (P < 0.85). CONCLUSIONS: Tendon transfers, especially for wrist extension, can be beneficial in improving upper extremity joint positioning in children with spastic hemiplegia. However, significant impairment in hand function persists.
[Van Heest, A. E., Ramachandran, V., Stout, J., Wervey, R. & Garcia, L. (2008). Quantitative and qualitative functional evaluation of upper extremity tendon transfers in spastic hemiplegia caused by cerebral palsy. Journal of Pediatric Orthopedics, 28(6), 679-83.]
[ Abstract ]
7. Subcutaneous Achilles tendon lengthening in the treatment of spastic equinus contracture
Background. Despite the significant progress in medicine in recent years, the number of children with cerebral palsy world-wide is growing systematically, often causing treatment problems. The goal of the present study was to evaluate lengthening of the Achilles tendon in the subcutaneous treatment of equines contractures. Material and methods. We analyzed 104 patients treated in Adult and Pediatric Orthopedics Clinic at the Lodz medical University from 1984 to 2001, in the course of multi-level release in the soft tissues. 53 patients reported for follow-up examinations, and 42 of these were selected for lengthening of the Achilles tendon using the White or Hoke methods. In 20 cases the operation was bilateral, giving a total of 62 feet. The average age at surgery was 6.19 years (range 2-13 years). All these patients presented with spastic palsy. Results. All patients or caregivers, and if possible the child as well, reported significant improvement of the overall clinical status and better gait efficiency. There were no complications in the healing of the surgical wounds. In a clear majority of cases no scars were visible on the skin. The appearance of the Achilles tendon did not show signs of surgical intervention and resembled normal structures. No heel deformities occurred. Conclusions. There was no essential difference in long-term outcome, and traditional methods. In view of the simplicity of operation, the cosmetic outcome, and earlier resumption of rehabilitation, subcutaneous lengthening should be considered the method of choice.
[Borowski, A., Synder, M. & Sibinski, M. (2004). Subcutaneous Achilles tendon lengthening in the treatment of spastic equinus contracture. Ortopedia, Traumatologia, Rehabilitacja, 6(6), 784-8.]
[ Abstract ]
8. Hyperactive stretch reflexes, co-contraction, and muscle weakness in children with cerebral palsy
The aim of this study was to examine the repeatability of and relationships among spasticity, co-contraction of agonist-antagonist, and muscle strength in children with cerebral palsy (CP). Eight children with spastic diplegic CP (five males, three females; Gross Motor Function Classification System [GMFCS] Levels I-III; mean age 10y 2mo [SD 2y 9mo], range 6-13y) and nine children in a comparison group (six males, three females; mean age 8y 10mo [SD 2y 4mo], range 6y to 12y 6mo) were assessed twice to examine repeatability of Composite Spasticity Scale, soleus stretch reflexes, electromyography (EMG) co-contraction ratio, and torque recorded during maximal isometric voluntary contraction of ankle dorsiflexors and plantarflexors. Sixty-one children with spastic CP, (54 diplegic, seven hemiplegic; 32 males, 29 females; GMFCS levels I-III; mean age 10y 8mo [SD 2y 9mo], range 6-15y) were then assessed to delineate possible correlations among these measures. Intraclass correlation coefficients (0.78-0.97) showed high data repeatability in both groups. Children with spastic CP demonstrated significantly larger soleus stretch reflex/M-response areas smaller torques, but larger EMG co-contraction ratios during both voluntary dorsiflexion and plantarflexion (all p<0.05). Children with spastic CP who had larger soleus stretch reflex/M-response areas demonstrated larger plantarflexion co-contraction ratio (r = 0.28), and produced smaller plantarflexion and dorsiflexion torques (r = -0.48 and -0.27 respectively). However, no correlation was noted between soleus stretch reflex and clinical spasticity. Our findings demonstrated that hyperactive soleus stretch reflex affected torque production of ankle muscles. Moreover, the severity of spasticity may not be fully described by either stretch reflex or tone measure alone.
[Poon, D. M. & Hui-Chan, C. W. (2008). Hyperactive stretch reflexes, co-contraction, and muscle weakness in children with cerebral palsy. Developmental Medicine and Child Neurology [epublication ahead of print].]
[ Abstract ]
9. Co-activity during maximum voluntary contraction: A study of four lower-extremity muscles in children with and without cerebral palsy
This study was designed to determine whether children with cerebral palsy (CP) showed more co-activity than comparison children in non-prime mover muscles with regard to the prime mover during maximum voluntary isometric contraction (MVIC) of four lower-extremity muscles. Fourteen children with spastic diplegic CP (10 males, four females; age range 4-10y), seven children with spastic hemiplegic CP (five males, two females; age range 5-10y), and 14 comparison children (eight males, six females; age range 4-11y) participated in the study. Gross Motor Function Classification System levels of the children with CP were as follows: eight children at Level I, seven children at Level II, five children at Level III, and one child at Level I V. Surface electromyographic recordings were made simultaneously from the vastus lateralis (VL), medial hamstrings (MH), tibialis anterior, and lateral gastrocnemius (LG) muscles during maximal voluntary contraction. Children with CP showed higher co-activity than the comparison children in both antagonist and adjacent muscles. This was particularly true when VL, MH, or LG muscles were engaged in MVIC. These findings may contribute to the weakness and abnormal movement patterns seen in CP, and they have implications for treatment.
[Tedroff, K., Knutson, L. M. & Soderberg, G. L. (2008). Co-activity during maximum voluntary contraction: A study of four lower-extremity muscles in children with and without cerebral palsy. Developmental Medicine and Child Neurology, 50(5), 377-81.]
[ Abstract ]
10. Synergistic muscle activation during maximum voluntary contractions in children with and without spastic cerebral palsy
We examined muscle recruitment patterns in children with cerebral palsy (CP) and comparison children without CP under conditions of maximum voluntary contractions. Three groups of children participated in the study: (1) 12 children with diplegic CP (eight males, four females; age range 4-10 y, mean age 7 y [SD 2 y 4 mo]); (2) six children with hemiplegic CP (four males, two females; age range 5-10 y, mean age 7 y 4 mo [SD 2 y]); and (3) 13 comparison children with normal motor function (seven males, six females; age range 4-11 y, mean age 7 y 2 mo, [SD 2 y]). The children with CP were classified according to the Gross Motor Function Classification System: eight were Level I, five were Level II, four were Level III, and one was Level IV. Surface electromyography was recorded from four proximal and distal lower extremity (LE) muscles. Children with CP more frequently activated a muscle other than the intended prime mover first, compared with the comparison children, especially when the prime mover was a distal muscle. For example, during ankle plantar flexion, when the lateral gastrocnemius muscle was the prime mover, children with hemiplegia showed preactivation of the tibialis anterior muscle and children with diplegia showed medial hamstring coactivation. In conclusion, children with CP showed considerable differences to the comparison children in how LE muscles were voluntarily activated. Greater understanding of muscle recruitment patterns under a variety of tasks may provide new directions for motor control retraining or other forms of intervention.
[Tedroff, K., Knutson, L. M. & Soderberg, G. L. (2006). Synergistic muscle activation during maximum voluntary contractions in children with and without spastic cerebral palsy. Developmental Medicine and Child Neurology, 48(10), 789-96.]
[ Abstract ]
11. Walking ability is related to muscles strength in children with cerebral palsy
The purpose of this study was to assess the relation between muscle strength and walking ability in children with bilateral spastic cerebral palsy at GMFCS levels I-III. 55 children (mean age 10.7, range 5-15) were tested for muscle strength in eight lower limb muscle groups with a handheld myometer. They were also tested with the Gross Motor Function Measure domains for standing and walking, running and jumping. Muscle strength in the legs was below normative predicted value in most of the children, with muscle weakness most pronounced around the ankle, followed by the hip muscles. There was a significant difference in muscle strength between GMFCS levels. There was also a moderate to high correlation between muscle strength and the GMFM, indicating that muscle weakness affects walking ability. Independently walking children had more than 50% of predicted muscle strength values.
[Eek, M. N. & Beckung, E. (2008). Walking ability is related to muscles strength in children with cerebral palsy. Gait & Posture, 28(3), 366-71.]
[ Abstract ]