Background

ACL rupture is a common knee injury with significant morbidity affecting over 100,000 individuals annually. Reconstruction is performed to restore joint stability, reduce the development of post-injury osteoarthrosis, and allow the safe return to sport and activity. Post-operative rehabilitation is a balance between speedy recovery and complication risk. However, little is known about which patients may experience greatest difficulty in an abbreviated rehabilitation period.

Methods

After institutional review board approval, manual record extraction was performed on all ACL reconstructed patients by a single surgeon at a single center between February 1, 2010 to June 30, 2015. Most pertinent data collected included patient demographics, injury information, BMI, ASA status, surgical information, pre-operative pain level and date of patient attainment of maximum medical improvement (defined by patient’s ability to achieve full range of knee motion, symmetric patellar mobility, symmetric knee strength on manual muscle testing, and negative Lachman’s). The primary outcome of interest in this study was the restoration to full functional recovery after surgery and BMI associated with the status of return as quantified by achieving symmetry to the contralateral extremity which equated to a release to full activity. Pearson test or Spearman test were used, respectively, for bivariate correlation between pain scores and BMI as well as Age, ASA score, primary vs. revision status, associated meniscal procedures and associated chondroplasty procedures and MMI status. Binary logistic regression was used to determine correlation between BMI and MMI.

Results

A total of 159 patients (47% male; mean age, 39 years +/- 11 years; range 7-66 years) were included. Patient BMI average was 28.3 kg/m2 +/- 6.4 kg/m2. 68.3% of patients reached all goals to meet MMI requirements by 3 months; median time to MMI for all patients was 113 days. Binary logistic regression analysis found a significant relationship between patient BMI and probability of reaching MMI, lower BMI lead to higher probability of MMI (Wald test, p = 0.039). There was also a correlation between pre-operative pain score and BMI. Higher BMI was associated with more pre-operative pain. (Pearson test, p=0.047), and bivariate analysis demonstrated that there was correlation between pre-operative pain score and time to MMI. Less pain led to earlier MMI (Spearman test, p=0.033). Additionally, it was found that a greater proportion of the successfully abbreviated cohort suffered non-contact injuries vs. contact injuries (Pearson’s test, p=0.027). No correlation was found between patient age (Spearman’s test, p=0.395), ASA score (Spearman’s test, p=0.465), primary vs revision status (Pearson’s test, p=0.792), associated meniscal (Pearson’s test, p=0.439) or chondroplasty (Pearson’s test, p=0.377) procedures and MMI status at 3 months.

Conclusions

While abbreviated rehabilitation after ACL reconstruction is an appealing post-operative plan, it should be noted that both a greater BMI and higher pre-operative pain scores may result in the need for greater time to achieve similar results as compared to those with lower BMI and less pre-operative pain complaints. Care should also be taken to identify individuals who have suffered more traumatic, contacted ACL ruptures and to allow for more time in the rehabilitation period.