Research Award Details

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The Effect of Knee Height Asymmetry on Gait Biomechanics

Grant Recipient: Haluk Altiok, MD

Co-Investigators:
Institution:
Shriners Hospital for Children, Chicago
Presentations & Publications:
Presentations:
Simon JC, Kruger KM, Krzak J, Altiok H, Harris GF. Joint Contact Force Model for Patients with Knee Height Asymmetry. Proceedings of the Gait and Clinical Movement Analysis Society. June 1-5, 2020, West Chester, PA. Podium presentation. [Conference canceled due to COVID-19]

       - Selected for presentation as part of the Gait and Clinical Movement Analysis Society (GCMAS)           Educational Webinar series.

Simon JC, Kruger KM, Krzak JJ, Altiok H, Harris GF. Joint Contact Force Model For Patients With Knee Height Asymmetry. Transactions of the 66th Annual Meeting of the Orthopaedic Research Society. February 13-16, 2021. Virtual poster presentation.

Simon JC, Kruger KM, Krzak JJ, Flanagan A, Kawaiah A, Burnham R, Sienko S, Buckon C, Bauer J, Harris GF, Altiok H. Mechanical Work at the Knee Joint for Cases with Knee Height Asymmetry. Proceedings of the American Society of Biomechanics Annual Conference. August 10-13, 2021. Virtual poster presentation.

Altiok H, Simon JA, Flanagan A, Kawaiah A, Burnham R, Sienko S, Buckon C, Bauer J, Kruger KM, Krzak JJ. The Effect of Knee Height Asymmetry on Gait Biomechanics. Submitted to Orthopaedic Research Society Annual Meeting
Further Funding:
Further grant obtained as result of POSNA funding:
Grant Submitted as a Shriners Clinical Research Grant - Multi-Center Study: The Effect of Knee Height Asymmetry on Gait. 3 year grant, Proposed Budget: $449,679
Additional Information:
Study Aims:
1. Establish what the average knee joint line height asymmetry is among patients who underwent limb equalizing procedures (e.g. epiphysiodesis, distraction osteogenesis, etc.) through radiographic indexing, and calculate tibia to femur ratio for each extremity.
2. Using gait analysis, calculate tri-axial knee kinematics, joint reaction forces, moments, power and total mechanical work done by each extremity.
3. Identify common gait abnormalities among post-operative patients by performing an instrumented gait analysis.
4. Investigate associations between KHA and gait biomechanics using measures of mechanical work, the biomechanical efficiency quotient (BEQ), and muscle/joint reaction forces.

Research Findings:
A population of children who had successfully underwent limb equalizing procedures to correct LLD to within 1.5 cm (KHA group) and an age-matched control group were recruited into the study. The KHA group consisted of 16 participants (8F, average age=17.5y±2.0) and the Control group consisted of 10 participants (5F, average age=16.3±1.9).

Aim 1:
The knee joint line height asymmetry was defined with the difference in tibia to femur ratio (T/F ratio) between limbs (T/F ratio symmetry index). There was a significant difference between the Control and KHA groups in T/F ratio (p=0.04) and the T/F ratio symmetry index (p<0.001).



Aims 2 and 3:
Gait kinematics and kinetics were compared between the KHA and Control Groups. The KHA patients showed a lower peak hip flexion moment during stance (both limbs), decreased foot progression angle ROM (on the side with the short tibia), decreased peak knee flexion angle (long tibia), increased pelvic tilt range of motion overall, decreased ankle flexion angle ROM (short tibia), and decreased peak knee flexion moment during swing phase (short tibia) compared to controls. A summary of results is included below.

Table 1: Summary of gait differences between groups. Red p-values indicate significant differences

Aim 4:
Pearson’s correlation coefficient (r) was used to analyze relationships between T/F ratio and work, T/F ratio symmetry and work, and T/F ratio symmetry and work symmetry index. The correlation analysis showed a weak correlation between T/F ratio and work generated (r=0.10) and total work (r=0.12). A higher but still weak correlation was found between limb symmetry (difference between left and right T/F ratios) and work generated (r=0.25) and total work (r=0.10). Moderate correlation was found between limb symmetry and the difference in work generated (r=0.55) and total work (r=0.46).


Figure 1: a) Relationship between work and T/F ratio, b) Relationship between work and limb symmetry (difference between left and right T/F ratios), and c) Relationship between difference in work and limb symmetry

Clinical takeaway message: Previous investigation had indicated that an increased tibial-femoral length ratio was a significant predictor of ipsilateral hip and knee arthritis [8]. The current results demonstrate that symmetry of T/F ratios between sides is more predictive of total work and work generated than the T/F ratio alone. These findings may have implications for management of LLD given that alterations in joint loading during gait are associated with an increased incidence of osteoarthritis [10]. As a result, surgeons may want to consider prioritizing achieving knee height symmetry as a postoperative goal when correcting limb length discrepancy.

KHA results in asymmetrical loading of lower extremity joints during gait which may contribute to future osteoarthritic changes. Surgeons should consider limb symmetry when correcting LLD in children.