Reliability of lateral single-leg drop landing test on patients after anterior cruciate ligament reconstruction: A three-dimensional motion analysis

Abstract

Background: The landing biomechanics are often assessed in individuals with anterior cruciate ligament reconstruction (ACLR) to evaluate rehabilitation outcomes, prevent recurrent injury and enhance sports performance. The highest peak knee valgus angle was reported in lateral landing which was closely associated with non-contact ACL injuries. A single-leg drop landing test (SLDLT) is commonly used as a screening test for the dynamic stability of knee, However, the reliability and validity of the test in patients received ACLR is uncertain.

Purpose: This study aimed to investigate the reliability and validity of lateral SLDLT in both intra-and inter-sessions on the kinematics of lower limbs after received ACLR.

Methods: Twelve subjects (4 females and 8 males) who received ACLR with a mean age of 29.4 (SD±1.66) were recruited. Five trials of lateral SLDLT were performed from 30cm-height platform in a biomechanics laboratory. Then the five trials were repeated on both legs for comparison. The first 100ms was analyzed since this period was the most vulnerable to injury. The mean values of normalized vertical ground reaction force (NVGRF) and local maxima of the hip, knee and ankle angles in all three planes were analyzed. The same operator repeated the above procedure one week later for the inter-sessions reliability.

Results: For kinematics, the overall intra-session reliability [ICC (3, 1)] was 0.948-0.988, and inter-session reliability [ICC (3, K)] was 0.618-0.982, respectively. Good to excellent reliability for the lateral SLDLT was observed in both intra-and inter-sessions. The reliability of NVGRF represented the stability of the physiological condition of the subjects and system because NVGRF was the least influenced by systematic errors. The intra-session reliability of NVGRF [ICC (3, 1)] was 0.899-0.936, and its inter-sessions reliability [ICC (3, K)] was 0.947-0.923. The ICC value of NVGRF on ACLR leg was lower than good leg that may associate with lower neuromuscular control in patients after received ACLR.

Conclusion: A lateral SLDLT is valid and reliable to evaluate the NVGRF and kinematics for lower limb after received ACLR. It can be used to assess the knee stability in lateral landing. It sheds the light on prevent recurrent injury and provide valid information for decision making of return-to-sport.