Background The initial graft tension applied at the time of anterior cruciate ligament (ACL) reconstruction alters joint contact and may influence cartilage health. The objective was to compare outcomes between two commonly used “laxity-based” initial graft tension protocols. Hypothesis We hypothesized that; 1) the high-tension group would have less knee laxity, improved clinical and patient-oriented outcomes, and less cartilage damage than the low-tension group after 36-months of healing, and 2) the outcomes of the high-tension group would be equivalent to those of a matched control group. Study Design Randomized controlled clinical trial. Methods Ninety patients with isolated unilateral ACL injuries were randomized to undergo ACL reconstruction using one of two initial graft tension protocols; 1) autografts tensioned to restore normal anteroposterior (AP) laxity at the time of surgery (i.e., “low-tension”; n=46) and 2) autografts tensioned to over-constrain AP laxity by 2 mm (i.e., “high-tension”; n=44). Sixty matched healthy subjects formed the control group. Outcomes were assessed pre-operatively, intra-operatively, and at 6-, 12- and 36-months after surgery. Results No significant differences were found between the two initial graft tension protocols for any of the outcome measures at 36-months. However, there were differences when comparing the two treatment groups to the control group. On average, AP laxity was 2 mm greater in the ACL reconstructed groups than in the control group (p<.007). IKDC knee evaluation scores (p<0.001), peak isokinetic knee extension torques (p<.027), and 4 out of 5 of the Knee Osteoarthritis Outcome Scores (KOOS; p<.05) were significantly worse than the control group. SF-36 scores and re-injury rates were similar between groups at 36-months. Although there were significant radiographic and MRI changes present in the ACL reconstructed knees of both treatment groups, the magnitude was relatively small and likely clinically insignificant at 36-months. Conclusions Both laxity-based initial graft tension protocols produced similar outcomes without fully restoring joint function and KOOS scores when compared to the control group. There was minimal evidence of cartilage damage 36-months after surgery.

Background Clinical, functional and patient-oriented outcomes are commonly used to evaluate the efficacy of treatments following ACL injury; however, these evaluation techniques do not directly measure the biomechanical changes that occur with healing. Purpose To determine if the magnetic resonance (MR) image-derived parameters of graft volume and signal intensity (SI), which have been used to predict the biomechanical (i.e., structural properties) of the graft in animal models, correlate with commonly used clinical (anteroposterior (AP) knee laxity), functional (1-leg hop) and patient-oriented outcome measures (KOOS) in patients 3- and 5-years after ACL reconstruction. Study Design Descriptive Laboratory Study Methods Using a subset of participants enrolled in an ongoing ACL reconstruction clinical trial, AP knee laxity, 1-legged hop test, and KOOS were assessed at 3- and 5-year follow-up. 3-D T1-weighted MR images were collected at each visit. Both the volume and median SI of the healing graft were determined and used as predictors in a multiple regression linear model to predict the traditional outcome measures. Results Graft volume combined with median SI in a multiple linear regression model predicted 1-legged hop test at both the 3-year and 5-year follow-up visits (R2=.40, p=.008 and R2=.62, p=.003, respectively). Similar results were found with 5-year follow up for the KOOS quality of life (R2=.49, p=.012), sport_function (R2=.37, p=.048), pain (R2=.46, p=.017) and symptoms (R2=.45, p=.021) sub-scores, though these variables were not significant at 3 years. The multiple linear regression model for AP knee laxity at 5-year follow-up approached significance (R2=.36, p=.088). Conclusion The MR parameters (volume and median SI) used to predict ex vivo biomechanical properties of the graft in an animal model have the ability to predict clinical or in vivo outcome measures in patients at 3- and 5-year follow-up.

PURPOSE OF REVIEW: The recent literature on the factors that initiate and accelerate the progression of osteoarthritis following ligament injuries and their treatment is reviewed. RECENT FINDINGS: The ligament-injured joint is at high risk for osteoarthritis. Current conservative (e.g. rehabilitation) and surgical (e.g. reconstruction) treatment options appear not to reduce osteoarthritis following ligament injury. The extent of osteoarthritis does not appear dependent on which joint is affected, or the presence of damage to other tissues within the joint. Mechanical instability is the likely initiator of osteoarthritis in the ligament-injured patient. SUMMARY: The mechanism osteoarthritis begins with the injury rendering the joint unstable. The instability increases the sliding between the joint surfaces and reduces the efficiency of the muscles, factors that alter joint contact mechanics. The load distribution in the cartilage and underlying bone is disrupted, causing wear and increasing shear, which eventually leads to the osteochondral degeneration. The catalyst to the mechanical process is the inflammation response induced by the injury and sustained during healing. In contrast, the inflammation could be responsible for onset, while the mechanical factors accelerate progression. The mechanisms leading to osteoarthritis following ligament injury have not been fully established. A better understanding of these mechanisms should lead to alternative surgical, drug, and tissue-engineering treatment options, which could eliminate osteoarthritis in these patients. Progress is being made on all fronts. Considering that osteoarthritis is likely to occur despite current treatment options, the best solution may be prevention.