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Midstance hamstring length is a better indicator for hamstring lengthening procedures than initial contact length.
Sam Augsburger1, Hank White1, Henry Iwinski1
1Shriners Hospitals for Children Medical Center, 110 Conn Terrace, Lexington, KY 40508, United States.
Gait & Posture
|June 3, 2020
Summary
Hamstring length at midstance is a better predictor of crouch gait surgery outcomes than at initial contact. Using midstance criteria reduces postoperative knee hyperextension, improving surgical success for children with static encephalopathy.
Area of Science:
- Orthopedics
- Pediatric Gait Analysis
- Biomechanical Engineering
Background:
- Children with static encephalopathy often exhibit crouch gait, characterized by excessive knee and hip flexion.
- Hamstring-lengthening surgery is a common intervention, but outcomes can vary, with some patients experiencing persistent crouch or developing debilitating knee hyperextension.
Purpose of the Study:
- To evaluate the efficacy of hamstring muscle-tendon length at midstance as a surgical criterion for hamstring lengthening procedures.
- To determine if using midstance measurements improves postoperative outcomes and reduces the incidence of knee hyperextension compared to initial contact measurements.
Main Methods:
- A simplified hamstring length model was retrospectively applied to 152 subjects' pre- and postoperative 3D gait analysis data.
- Kinematic data from initial contact and midstance phases were analyzed to assess surgical indications and outcomes.
Main Results:
- Short hamstrings at midstance significantly reduced the risk of postoperative knee hyperextension (6%) compared to short hamstrings at initial contact alone (15%).
- Applying criteria for short hamstrings at both initial contact and midstance eliminated hyperextension cases (0%).
Conclusions:
- Hamstring length at midstance is a more reliable predictor of postoperative knee hyperextension risk than length at initial contact.
- A more conservative surgical approach using midstance criteria may improve outcomes but could exclude some candidates who might benefit from surgery.
