Low Rates of Radiographic Knee Osteoarthritis 5 Years After ACL Reconstruction or Rehabilitation Alone: The Delaware-Oslo ACL Cohort Study

Ingelsrud L, Roos EM, Silbernagel KG, Snyder-Mackler L, Risberg MA. Patient Acceptable Symptom State Thresholds for IKDC-SKF and KOOS at the 10-Year Follow-up After Anterior Cruciate Ligament Injury: A Study From the Delaware-Oslo ACL Cohort

Background

Clinicians need thresholds for the Patient Acceptable Symptom State (PASS) and Treatment Failure to interpret group-based patient-reported outcome measures after anterior cruciate ligament (ACL) injury. Validated thresholds that are crucial for accurately discerning patient symptom state and facilitating effective interpretation have not been determined for long-term follow-up after ACL injury.

Purpose

To calculate and validate thresholds for PASS and Treatment Failure for the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF) and the Knee injury and Osteoarthritis Outcome Score (KOOS) subscales at the 10-year follow-up after ACL injury.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 163 participants with unilateral ACL injury (treated with reconstruction or rehabilitation alone) from the Delaware-Oslo ACL Cohort were included. Thresholds for PASS were calculated for IKDC-SKF and KOOS subscales using anchor-based predictive modeling and receiver operating characteristic (ROC) analysis. Too few participants had self-reported Treatment Failure to calculate thresholds for that outcome. Nonparametric bootstrapping was used to derive 95% CIs. The criterion validity of the predictive modeling and ROC-derived thresholds were assessed by comparing actual patient-reported PASS outcome with the calculated PASS outcome for each method of calculation and calculating their positive and negative predictive values with respect to the anchor questions.

Results

A total of 127 (78%) participants reported satisfactory symptom state. Predictive modeling PASS thresholds (95% CIs) were 76.2 points (72.1-79.4 points) for IKDC-SKF, 85.4 points (80.9-89.2 points) for KOOS Pain, 76.5 points (67.8-84.7 points) for KOOS Symptoms, 93.8 points (90.1-96.9 points) for KOOS activities of daily living, 71.6 points (63.4-77.7 points) for KOOS Sports, and 59.0 points (53.7-63.9 points) for KOOS quality of life (QoL). Predictive modeling thresholds classified 81% to 93% of the participants as having satisfactory symptom state, whereas ROC-derived thresholds classified >50% as unsatisfied. The thresholds for IKDC-SKF, KOOS Sports, and KOOS QoL resulted in the most accurate percentages of PASS among all identified thresholds and therefore demonstrate the highest validity.

Conclusion

Predictive modeling provided valid PASS thresholds for IKDC-SKF and KOOS at the 10-year follow-up after ACL injury. The thresholds for IKDC-SKF, KOOS Sports, and KOOS QoL should be used when determining satisfactory outcomes. ROC-derived thresholds result in substantial misclassification rates of the participants who reported satisfactory symptom state.

Clinically Relevant Subgroups Among Athletes Who Have Ruptured Their Anterior Cruciate Ligaments: A Delaware-Oslo Cohort Study

OBJECTIVE

To identify subgroups of individuals with anterior cruciate ligament (ACL) injuries based on patient characteristics, self-reported outcomes, and functional performance at baseline, and to associate subgroups with long-term outcomes after ACL rupture.

METHODS

A total of 293 participants (45.7% male, mean ± SD age 26.2 ± 9.4 years, days from injury 58 ± 35) were enrolled after effusion, pain, and range of motion impairments were resolved and quadriceps strength was at least 70% of the uninvolved limb. Mixture modeling was used to uncover latent subgroups without a prior group classification using probabilistic assignment. Variables include demographics, functional testing, and self-reported outcome measures. Radiographic evidence of osteoarthritis (OA; i.e., Kellgren/Lawrence grade of ≥1) in the involved knee at 5 years after injury was the primary outcome of interest. Chi-square tests assessed differences in the presence of radiographic OA in the involved knee between subgroups at 5 years after ACL rupture. Secondary outcomes of interest included radiographic OA in the uninvolved knee, return to preinjury sport by 2 years, operative status, and clinical OA (classified using Luyten et al criteria) at 5 years.

RESULTS

Four distinct subgroups exist after ACL rupture (younger good self-report, younger poor self-report, older poor self-report, older good self-report) with 30%, 31%, 47%, and 53%, respectively, having involved knee OA. The percentage of radiographic OA was not significantly different between the groups (P = 0.059).

CONCLUSION

The prevalence of OA in all subgroups is highly concerning. These results suggest there are unique subgroupings of individuals that may guide treatment after ACL rupture and reconstruction by providing support for developing a patient-centered approach.

Four Distinct 5-Year Trajectories of Knee Function Emerge in Patients Who Followed the Delaware-Oslo ACL Cohort Treatment Algorithm

BACKGROUND

Impairments and dysfunction vary considerably after anterior cruciate ligament (ACL) injury, and distinct subgroups may exist.

PURPOSE

(1) To identify subgroups of patients with ACL injury who share common trajectories of patient-reported knee function from initial presentation to 5 years after a treatment algorithm where they chose either ACL reconstruction (ACLR) plus rehabilitation or rehabilitation alone. (2) To assess associations with trajectory affiliation.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We included 276 patients with a acute first-time complete unilateral ACL injury. All patients underwent a 5-week neuromuscular and strength training program before a shared decision-making process about treatment. Within their latest attended follow-up, 62% of patients had undergone early ACLR (<6 months after the 5-week program), 11% delayed ACLR (>6 months after the 5-week program), and 27% progressive rehabilitation alone. Patients completed the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF) at inclusion, after the 5-week program, and at 6 months, 1 year, 2 years, and 5 years after ACLR or completion of the 5-week program (patients treated with rehabilitation alone). We used group-based trajectory modeling to identify trajectories of IKDC-SKF and multinomial logistic regression to assess associations with trajectory affiliation.

RESULTS

Four distinct trajectories of IKDC-SKF were identified: Low (n = 22; 8.0% of the cohort), Moderate (n = 142; 51.4%), High (n = 105; 38.0%), and High Before Declining (n = 7; 2.5%). The High trajectory had higher scores at inclusion than the Moderate trajectory, but both improved considerably within 1 year and had thereafter stable high scores. The High Before Declining trajectory also started relatively high and improved considerably within 1 year but experienced a large deterioration between 2 and 5 years. The Low trajectory started low and had minimal improvement. New knee injuries were important characteristics of the High Before Declining trajectory, concomitant meniscal injuries were significantly associated with following the Low (vs Moderate) trajectory, and early/preoperative quadriceps strength and hop symmetry (measured at inclusion) were significantly associated with following the High (vs Moderate) trajectory.

CONCLUSION

We identified 4 distinct 5-year trajectories of patient-reported knee function, indicating 4 subgroups of patients with ACL injury. Importantly, 88% of the patients who followed our treatment algorithm followed the Moderate and High trajectories characterized by good improvement and high scores. Due to eligibility criteria and procedures in our cohort, we can only generalize our model to athletes without major concomitant injuries who follow a similar treatment algorithm. Concomitant meniscal injuries and new knee injuries were important factors in the unfavorable Low and High Before Declining trajectories. These associations were exploratory but support the trajectories' validity. Our findings can contribute to patient education about prognosis and underpin the importance of continued secondary injury prevention.