Faculty Collaboration Database

How does patellar tendon advancement alter the knee extensor mechanism in children treated for crouch gait? Gait Posture 2018 Jul;64:248-254

Date

06/30/2018

Pubmed ID

29958159

Pubmed Central ID

PMC6181142

DOI

10.1016/j.gaitpost.2018.06.005

Scopus ID

2-s2.0-85049035195 (requires institutional sign-in at Scopus site)   16 Citations

Abstract

BACKGROUND: The patellar tendon advancement (PTA) procedure, often coupled with a distal femoral extension osteotomy (DFEO), is increasingly used to treat persistent crouch gait. In this study, we investigated relationships between patella position, knee flexion, and the patellar tendon moment arm in children treated with the DFEO and PTA procedures.

METHODS: We retrospectively analyzed pre- and post-operative radiographs and gait metrics from 63 knees that underwent DFEO and PTA procedures at Gillette Children's Specialty Healthcare. A computational musculoskeletal model of the knee was used to simulate the PTA procedure and predict the effects on the patellar tendon moment arm.

RESULTS: Approximately 80% of the knees exhibited patella alta prior to surgery. Post-operatively, 86% of the knees exhibited patella baja. The surgically altered patella position produced a 13% increase in the patellar tendon moment arm in extended knee postures, which agreed well with model predictions. However, the computational model also suggests that baja may compromise patellar tendon moment arms in flexed knee postures. Crouch gait was significantly reduced postoperatively, with a 27 ± 18° reduction in average knee flexion in stance. There was considerable inter-subject variability in outcomes with nine knees not exhibiting a meaningful enhancement of knee extension (<15° change). The subjects who improved were significantly younger and exhibited greater enhancement of the patellar tendon moment arm after surgery.

CONCLUSIONS: This study shows that the PTA procedure enhances the lever arm of the knee extensor mechanism, and this factor may be important in resolving crouch gait.

Author List

Bittmann MF, Lenhart RL, Schwartz MH, Novacheck TF, Hetzel S, Thelen DG

Author

Rachel L. Lenhart MD Assistant Professor in the Orthopaedic Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cerebral Palsy
Child
Databases, Factual
Female
Gait
Gait Disorders, Neurologic
Humans
Knee Joint
Male
Osteotomy
Patella
Patellar Ligament
Postoperative Period
Range of Motion, Articular
Retrospective Studies
Tendon Transfer
Young Adult