Biomedical subjects

K Patrick Do

Publications and source records attributed to K Patrick Do.

4 recordsLinked to original sources

PubMed2005

Cross-correlation as a method for comparing dynamic electromyography signals during gait.

Current clinical interpretation of dynamic electromyography (EMG) data is usually based on qualitative assessments of muscle timing. Cross-correlation may provide a method for objectively comparing the timing and shape of EMG signals. This study used cross-correlation to compare EMG signals from different walking trials, different test sessions, and different individuals in able-bodied adults. Cross-correlation results (R-values) for different walking trials within a single test session were high, averaging > or = 0.90 for all muscles tested (R = 1.0 indicates exact agreement). Cross-correlation values were also high among trials from different test sessions conducted by the same and different examiners (average R > or = 0.78 for all muscles). R-values were much more variable when comparing different subjects (average 0.40-0.81, range 0.00-0.91). R-values were lower for the medial hamstrings and rectus femoris compared with the other muscles tested. These results suggest that cross-correlation may be useful for evaluating changes in an individual patient's muscle activation patterns, such as before and after surgery, but not for comparing EMG patterns among different individuals, such as between patients and normative data. This is especially true for biarticular muscles such as the hamstrings and rectus femoris, which may have variable activation patterns and/or increased sensitivity to electrode placement. Cross-correlation may also be useful for identifying appropriate muscles for transfer, identifying "outlier" trials within a test session, and selecting representative EMG curves for a given patient. The advantages of cross-correlation are that it considers shape of the EMG signal in addition to timing and that the assessments it provides are objective, rather than subjective.

Adult↗

PubMed2004

Gastrocnemius and soleus lengths in cerebral palsy equinus gait--differences between children with and without static contracture and effects of gastrocnemius recession.

Equinus gait is one of the most common abnormalities in children with cerebral palsy. Although it is generally assumed that the calf muscles are abnormally short in equinus gait, no studies have been done to confirm that the muscles are short and that this shortness contributes to the equinus. This study used musculoskeletal modeling combined with computerized gait analysis to examine medial gastrocnemius (MGAS), lateral gastrocnemius (LGAS), and soleus (SOL) musculotendinous lengths during equinus gait in children with cerebral palsy. All three muscles were abnormally short during equinus gait whether or not the children had equinus contractures (P < or = 0.005). Children with static contractures had shorter maximum static MGAS and LGAS lengths than children with dynamic equinus (P < or = 0.002). The children with static contractures had ratios of peak dynamic length to maximum static length close to 1.0 for MGAS and LGAS (1.005 +/- 0.015) but lower ratios for SOL (0.984 +/- 0.024). For the children with static contracture, these ratios did not change significantly after gastrocnemius recession (P > or = 0.14) because both static and dynamic lengths increased postoperatively (P < or = 0.04). These results support the current clinical understanding of the role of calf "tightness" in equinus gait, including the appropriateness and effectiveness of gastrocnemius recession for children with equinus contracture.

Ankle Joint↗

PubMedDate not supplied

Changes in pelvic rotation after soft tissue and bony surgery in ambulatory children with cerebral palsy.

The authors performed a retrospective review of pelvic rotation in 59 children with cerebral palsy who underwent lower extremity surgery and pre- and postoperative gait analysis. Two groups were studied: a femoral derotation osteotomy (FDRO) group and a soft tissue surgery only (no FDRO) group. Both groups exhibited abnormal pelvic rotation preoperatively and normalization of this abnormal pelvic rotation postoperatively. Though the mean change in pelvic rotation was small (3.3 degrees +/- 6.0 degrees), some patients demonstrated postoperative changes as large as 21 degrees. Variability in pelvic rotation was greater in the no FDRO group than in the FDRO group. Improvement in pelvic rotation occurred both in children with unilateral (hemiplegic) involvement and in those with bilateral (diplegic or quadriplegic) involvement. Surgeons planning lower extremity surgery in children with cerebral palsy should expect improvement in abnormal pelvic rotation in both hemiplegic and diplegic patients, whether or not bony surgery is planned in addition to soft tissue surgery.

Cerebral Palsy↗

PubMedDate not supplied

Reliability and validity of visual assessments of gait using a modified physician rating scale for crouch and foot contact.

This study evaluates the visual assessment of gait using portions of the Physicians' Rating Scale (PRS). Thirty children with pathologic gait were evaluated "live" and using full- and slow-speed video. Interobserver reliability (weighted kappa) was 0.57 to 0.74 for foot contact, 0.69 to 0.71 for crouch, 0.30 to 0.40 for hip flexion, 0.57 to 0.65 for knee flexion, and 0.42 to 0.52 for dorsiflexion in stance. Intraobserver reliability (comparing the three conditions) was 0.50 to 0.78 for foot contact, 0.71 to 0.80 for crouch, 0.26 to 0.44 for hip flexion, 0.60 to 0.86 for knee flexion, and 0.39 to 0.61 for dorsiflexion. Observers were correct only 12% to 32% of the time when reporting less than 0 degrees of dorsiflexion and 0% to 29% of the time when reporting more than 20 degrees of hip flexion due to overestimation of hip flexion and underestimation of ankle dorsiflexion. These errors could lead some clinicians to presume the presence of contractures that do not actually exist. Visual assessment using the PRS does not appear to accurately measure what it is most commonly used to assess: ankle position in stance.

Adolescent↗