Volume 60: Issue 2

Context

Gait biomechanics and daily steps are important aspects of knee-joint loading that change after anterior cruciate ligament reconstruction (ACLR). Understanding their relationship during the first 6 months post-ACLR could help clinicians develop comprehensive rehabilitation interventions that promote optimal joint loading after injury, thereby improving long-term knee-joint health.

Objectives

To compare biomechanical gait waveforms throughout stance at early time points post-ACLR in individuals with different daily step behaviors at 6 months post-ACLR and to examine how these gait waveforms compare with those of uninjured controls.

Design

Case-control study.

Setting

Laboratory.

Patients or Other Participants

A total of 32 individuals with primary ACLR assigned to the low-step group (LSG; n = 13) or the high-step group (HSG; n = 19) based on their average daily steps at 6 months post-ACLR and 32 uninjured matched controls.

Main Outcome Measure(s)

Gait biomechanics were collected at 2, 4, and 6 months post-ACLR for the ACLR groups and at a single session for the control group. Knee-adduction moment, knee-extension moment (KEM), and knee-flexion angle (KFA) waveforms were calculated during gait stance and then compared via functional waveform analyses. Mean differences and corresponding 95% CIs between groups were reported.

Results

Primary results demonstrated less KFA (1%–45% versus 79%–92% of stance) and greater KEM (65%–93% of stance) at 2 months and greater knee-adduction moment (14%–20% versus 68%–92% of stance) at 4 months post-ACLR for the HSG compared with the LSG. Knee-adduction moment, KEM, and KFA waveforms differed across various proportions of stance at all time points between the step and control groups.

Conclusions

Differences in gait biomechanics were present at 2 and 4 months post-ACLR between step groups, with the LSG demonstrating an overall more flexed knee and more profound stepwise underloading throughout stance than the HSG. The results indicate a relation between early gait biomechanics and later daily step behaviors post-ACLR.

Context

Slower habitual walking speed and aberrant gait biomechanics are linked to clinically significant knee-related symptoms and articular cartilage composition changes linked to posttraumatic osteoarthritis after anterior cruciate ligament reconstruction (ACLR).

Objectives

To (1) determine whether specific gait biomechanical variables can accurately identify individuals with clinically significant knee-related symptoms post-ACLR and (2) determine the corresponding threshold values, sensitivity, specificity, and odds ratios for each biomechanical variable.

Design

Cross-sectional study.

Setting

Laboratory.

Patients or Other Participants

A total of 71 individuals (38 female, 33 male; age = 21 ± 4 years, height = 1.76 ± 0.11 m, mass = 75.38 ± 13.79 kg, time after primary unilateral ACLR = 6.2 ± 0.4 months).

Main Outcome Measure(s)

Three-dimensional motion capture of 5 overground walking trials was used to calculate discrete gait biomechanical variables of interest during stance phase (first and second peak vertical ground reaction force [vGRF], midstance minimum vGRF, peak internal knee-abduction and -extension moments, and peak knee-flexion angle), along with habitual walking speed. Previously established Knee Injury and Osteoarthritis Outcome Score cutoff scores were used to define patients with (ie, symptomatic; n = 51) and those without (ie, asymptomatic; n = 20) clinically significant knee-related symptoms. Separate receiver operating characteristic curves and respective areas under the curve (AUCs) were used to evaluate the capability of each biomechanical variable of interest to identify individuals with clinically significant knee-related symptoms.

Results

Habitual walking speed (AUC = 0.66), vGRF at midstance (AUC = 0.69), and second peak vGRF (AUC = 0.76) demonstrated low to moderate accuracy for identifying individuals with clinically significant knee-related symptoms. Individuals who exhibited habitual walking speeds ≤ 1.27 m/s, midstance minimum vGRF ≥ 0.82 body weights, and second peak vGRF ≤ 1.11 body weights demonstrated 3.13, 6.36, and 9.57 times higher odds of experiencing clinically significant knee-related symptoms, respectively.

Conclusions

Critical thresholds for gait variables may be used to identify individuals with increased odds of clinically significant knee-related symptoms and potential targets for future interventions.

Context

Quadriceps strength is a key outcome for guiding rehabilitation and return to sport-specific activities after anterior cruciate ligament reconstruction (ACLR) surgery.

Objective

(1) Describe the quadriceps-strength–testing practices and barriers college athletic trainers (ATs) are using and experiencing when returning patients to sport-specific activities after ACLR. (2) Compare testing methods between college ATs working in the National Collegiate Athletic Association (NCAA) Division I setting and other college settings.

Design

Cross-sectional study.

Setting

Online survey.

Patients or Other Participants

Two hundred forty-three full-time collegiate ATs who had primarily overseen/directed an ACLR rehabilitation in the past 5 years (age = 34.8 ± 10.7 years, length of AT practice = 11.7 ± 9.3 years, NCAA Division I setting = 56%).

Main Outcome Measure(s)

Our survey included 4 sections: demographics, general ACLR rehabilitation practices, quadriceps-strength–testing methods and criteria, and quadriceps-strength–testing barriers.

Results

Knee-muscle strength was the most common (98%) outcome collegiate ATs used when determining whether an ACLR patient is ready to progress to sport-specific activities. Manual muscle testing was the most used testing method (57%), followed by isokinetic dynamometry (IKD) (48%), repetition maximum testing (35%) and handheld dynamometry (22%). Most ATs (63%–64%) used greater than 90% side-to-side symmetry as their return to sport-specific activities criterion. Lack of equipment needed (83%), lack of financial means (28%), and lack of training/education (20%) were the barriers that most limited ATs use of IKD testing, the gold standard testing method. Compared with ATs in other settings, a greater proportion of ATs working in the NCAA Division I setting used IKD testing (65% vs 28%) and a smaller proportion used manual muscle testing (47% vs 70%).

Conclusions

Although almost all college ATs considered knee-muscle strength an important outcome to assess when returning patients to sport-specific activities after ACLR, quadriceps-strength–testing practices were highly variable among ATs and may be affected by access to necessary resources.

We thank our 2024 manuscript reviewers for their hard work and dedication.

Alexandra Abbott, MD

Thomas E. Abdenour, DHSc, ATC

Shellie Acocello, PhD, ATC

Julie Agel, MA, ATC

Kazuma Akehi, PhD, LAT, ATC

Gordon Alderink, PT, PhD

Jeremy A. Alland, MD

Jon Almquist, ATC

Denise Alosa, MS, ATC

Saleh A. Alsaleh, PhD

B. J. Anderson, MD

J. C. Andersen, PhD, AT, PT

Morgan Anderson, PhD

Kristy B. Arbogast, PhD

Kirk J. Armstrong, EdD, ATC

Tara Armstrong, BS, ATC

Amanda J. Arnold, PhD, DPT, OCS, SCS

Breton M. Asken, PhD, ATC

Candace L. Ayars, PhD

Jennifer J. Bagwell, PhD, PT

Charlotte

Reliability and Validity of the Functional Assessment of Neurocognition in Sport (FANS): A Paradigm Shift in Post-Concussion Return-to-Sport Decision-Making

Landon B. LempkePhD, ATC,

Benjamin L. BrettPhD, and

Douglas P. TerryPhD,ABPP