Hop Testing Lacks Strong Association With Key Outcome Variables After Primary Anterior Cruciate Ligament Reconstruction: A Systematic Review

Abstract

Background: Single-legged hop tests are commonly used assessments in return to sport (RTS) testing after anterior cruciate ligament reconstruction (ACLR). Although these tests are commonly used, their predictive validity has not yet been established. Purpose: To determine the strength of association between hop testing and RTS, knee reinjury, subjective report of knee function, and posttraumatic knee osteoarthritis (PTOA) after primary ACLR. Secondarily, to determine whether hop testing is able to predict a favorable result on the same outcome variables. Study Design: Systematic review. Methods: A systematic, computer-assisted literature search was performed in PubMed/MEDLINE, CINAHL, EMBASE, SPORTDiscus, Cochrane Library, and ClinicalTrials.gov. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed when conducting and reporting this review. Primary outcome variables for this review were self-report of knee function, return to preinjury level of activity, presence of reinjury, and presence of PTOA. The Oxford Centre for Evidence-Based Medicine Levels of Evidence tool was used to assess the level of evidence for each included study. Quality assessment of each included study was performed through use of a modified Downs and Black scale. Available metrics were tabulated based on outcome variables. Results: Overall, 21 studies (4476 patients) met inclusion for this review. The majority of evidence (95.2%) was of moderate to high methodologic quality. The most commonly associated outcome measure was the International Knee Documentation Committee (IKDC) score, with Pearson correlation coefficients ranging from 0.20 to 0.60. The strength of association between the Knee injury and Osteoarthritis Outcome Score (KOOS) and hop testing ranged from −0.10 to 0.62 in 4 studies. In all, 10 studies examined the relationship between hop testing and RTS, with variable association statistics reported. No meaningful association was found between hop testing and knee reinjury in 2 studies. Worse preoperative hop testing was associated with PTOA in 1 study. Conclusion: Hop testing appears to possess fair association to subjective report of knee function measured by the KOOS and IKDC and a patient’s ability to RTS after ACLR. Insufficient evidence is available to determine the relationship between hop testing and PTOA and knee reinjury. Predictive validity cannot be established based on available literature.

Quadriceps Neuromuscular and Physical Function After Anterior Cruciate Ligament Reconstruction

“…24 Improved performance is believed to indicate a reduced risk of reinjury, although few authors have investigated this relationship. 36 Like muscle-strength tests, hop tests are often used to determine readiness to return to activity. Ideally, hop tests should be conducted on both limbs to evaluate symmetry; readiness to return to activity is evident with a limb-symmetry index !90%.…”

Poor functional performance 1 year after ACL reconstruction increases the risk of early osteoarthritis progression

“…Greater between limb asymmetry on the one-leg rise test 6–15 months post-ACL injury was associated with worse KOOS scores at 5 years 51. Due to the multifactorial fluctuating nature of life for a young active adult, it is likely many other subjective factors influence change in KOOS and IKDC scores, hence predicting PROs post-ACLR is challenging 16 52. Further research should consider potential psychosocial and contextual influences on PROs such as fear avoidance, confidence, coping and healthcare utilisation 53–57…”

“…Following ACLR, the link between functional performance and worsening symptomatic and early structural OA outcomes is unclear. While a single hop-for-distance test at 1 year post-ACLR was associated with the presence of tibiofemoral radiographic OA at 10 years,15 other studies have reported minimal association between postoperative functional performance and future radiographic OA 5–15 years post-ACLR 4 16 17. Prior studies focus on radiographic tibiofemoral OA, and do not evaluate early structural change (ie, worsening) in individual joint features.…”

“…Functional performance may possess differing relationships with change in individual early OA features and PROs. Functional performance deficits at the time of return to sport (RTS) are often associated with worse PROs 2–3 years after ACL injury,16 24–28 with few studies evaluating the change in PROs beyond 3 years, due to cross-sectional design. It is this change in PROs and structural outcomes that equates to the problematic accelerated trajectory of symptomatic OA in young adults post-ACLR.…”

Can We Capitalize on Central Nervous System Plasticity in Young Athletes to Inoculate Against Injury?

“…[65,109]. Further, some commonly used metrics, such as bilateral symmetry, may not be as important as once thought, as hop testing symmetry does not mirror quad strength symmetry and restoring bilateral hop symmetry is not always effective for reducing ACL-reinjury [67,75,82,100,157]. Conversely, quadriceps strength deficits are well documented post ACLR and may provide a related indicator of residual deficits following surgery [120].…”