Interrater and Intrarater Reliability and Discriminant Validity of a Pediatric Lower Extremity Physical Therapy Clearance Test

Abstract

Background: Few studies have validated when an athlete can safely return to sports, and even fewer have identified when he or she no longer requires physical therapy after surgery. Discontinuing physical therapy is often dictated by insurance restrictions, but most studies have suggested that the decision should be multifactorial, stemming from patient-derived subjective outcome questionnaires, clinical examination, and isokinetic and functional testing.

Purpose/hypothesis: The purpose of this study was to establish discriminant validity and reliability of an objective physical therapy clearance (PTC) test in a clinical setting. The hypotheses were that the PTC test (1) will demonstrate different scores between normal and postoperative cohorts and (2) will have acceptable inter- and intraobserver reliability.

Study design: Cohort study (diagnosis); Level of evidence, 3.

Methods: Four cohorts (27 total participants; age range, 12-18 years) underwent the PTC test: 9 adolescents 6 months after anterior cruciate ligament reconstruction, 4 adolescents 6 weeks after partial meniscectomy, 5 adolescents with nonstructural knee pain, and 9 control/healthy participants without any lower extremity complaint. The PTC test included a dynamic warm-up, objective measures (knee range of motion, thigh girth, and muscle motor tone), functional strength tests (heel raises, single-leg dips, hop tests, tuck jumps), and agility tests (shuffle and sprint T-test). Each testing session was videotaped and scored live by the physical therapist administering the test, and then scored via the video recording by an independent physical therapist and 2 orthopaedic surgeons.

Results: The PTC test was found to have discriminant validity between the control cohort and both cohorts with previous surgery. The single-leg dip, single-leg hop, and vertical tuck jump were the most discriminatory components. The PTC test had moderate to almost perfect intrarater reliability (κ = 0.57-1), but only fair to moderate interrater reliability among video graders (κ = 0.29-0.58) and slight to substantial reliability between video graders and the live PT rater (κ = 0.19-0.63).

Conclusion: The PTC test was found to have moderate inter- and intraobserver agreement, with the ability to discriminate between postoperative and control patients.

Keywords: adolescent; functional test; pediatric; physical therapy; return to sport.

Figure 1.

Forest plot demonstrating effect size (±95% CI) for total raw scores based on post hoc comparison of patient groups. ACL, anterior cruciate ligament.

Figure 2.

Forest plot demonstrating effect size (±95% CI) for total normalized scores based on post hoc comparison of patient groups. An effect size of ≥0.8 was considered a large magnitude of difference. ACL, anterior cruciate ligament.

Figure 3.

Comparative photographs demonstrating 2 different outcomes for the vertical tuck jump: the child on the left failing the test and the one on the right demonstrating a passing test. Images courtesy of SD PedsOrtho.