Christina Allen, MD, FAAOS, FAOA

1. AOSSM Multi-center ACL revision (MARS) study- co-investigator (2006-present)

Also member of Mars Scientific Advisory Board since 2009

This study has two general goals: 1) to evaluate the functioning of patients who undergo revision Anterior Cruciate Ligament reconstruction several years after surgery using a large-scale prospective study design and 2) to identify factors that predict patient-reported outcomes two years after ACL revision surgery.

Aim 1. To determine outcomes of patients who undergo revision ACL reconstruction.

Aim 2. To determine predictors of patient-reported symptoms and functioning two years after revision ACL reconstruction.

Aim 3. To determine risk factors/predictors of osteoarthritis for patients undergoing revision ACL reconstruction.

Aim 4. To determine predictors of level of activity at two-year follow-up for patients undergoing revision ACL reconstruction.

Aim 5. To determine risk factors/predictors of subsequent injury to the index ACL graft or the ACL in the contralateral knee.

Collaborations: Study funded by American Orthopaedic Society for Sports Medicine, Musculoskeletal Transplant Foundation and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Surgical data that are collected electronically in the physician's office during this study will be stored on a server at Vanderbilt University which is serving at the data management center for this multi-center study.

Status: 25 patients recruited from UCSF to date.

This Project has been very prolific in terms of publications and awards. • Winner American Orthopaedic Society for Sports Medicine O’Donoghue Award , July 2014, Seattle Washington, “Revision Anterior Cruciate Ligament Reconstruction Graft Choice Impact on Outcome in the MARS Cohort” Wright RW and the MARS Group (includes CR Allen)

•awarded NIH R01 competitive renewal grant in early 2017 to evaluate the 10 year onsite follow up.

• Winner of the 2019 Kappa Delta Ann Doner Vaughn Award for Outstanding Orthopaedic Research. Wright RW, Allen CR and the Multicenter ACL Revision Study (MARS) Group. As Member of MARS Scientific Advisory Board was named as specific recipient of award

2. Surgical Repair of Proximal Hamstring Avulsion Injuries: Functional Outcomes and Ultrasound Correlation with Confirmation of Healing This study is designed to look at the clinical outcomes of the Surgical Repair of Acute and Chronic Proximal Hamstring Ruptures. A retrospective chart review was performed to identify all patients treated surgically for complete proximal hamstring avulsion injuries by a single surgeon at a single institution from 2012-2016. All patients treated surgically and already cleared to return to full activities were asked to present to clinic to undergo functional and strength testing. Ultrasonography was also performed to assess for muscular fatty infiltration.

3. Quantitative MR Imaging Evaluation of Articular Cartilage and Kinematic changes in the knee after meniscectomy-

Principal Investigator (2011-Present)

The purpose of this study is to use high resolution cartilage sensitive MRI to evaluate the changes seen in the knee following acute meniscus tears in order to determine the effects of meniscal injury and arthroscopic debridement on the knee kinematics and cartilage biochemical properties. We specifically will evaluate alterations in the contact area and meniscal kinematics before and after surgery, and evaluate changes in the cartilage at one year after surgery to evaluate for early articular cartilage changes

Specific Aim I:

Evaluate the effects of a meniscus tear on in vivo contact area and meniscus kinematics.

This will be determined by obtaining pre-operative MRI and evaluating the initial contact area patterns at two knee flexion angles (30 degrees and 0 degrees) and knee kinematics compared to the contralateral knee. We hypothesize that a meniscal tear will lead to altered tibiofemoral contact patterns (total area and contact centroid) and altered meniscus kinematics.

Specific Aim II:

Determine the effects of arthroscopic partial meniscectomy on in vivo contact area and meniscus kinematics.

We will evaluate the effects of partial meniscectomy on contact area patterns and meniscus kinematics by obtaining a post-operative MRI to compare changes in contact area patterns and kinematics to the pre-operative condition. We hypothesize that surgical resection of the meniscus tear will not change contact area patterns or kinematics.

Specific Aim III:

Evaluate the results of arthroscopic partial meniscectomy on cartilage biochemical properties using T1rho, T2, and SPGR high resolution MRI.

We will evaluate the effects of partial meniscectomy on cartilage biochemical properties with high resolution cartilage-specific sequences at 6 months following surgery and comparing them to pre-operative values. We hypothesize that there will be changes consistent with early cartilage breakdown in the compartment that had a meniscal tear.

Souza RB, Wu SJ, Morse LJ, Subburaj K, Allen CR, Feeley BT. Cartilage MRI relaxation times after arthroscopic partial medial meniscectomy reveal localized degeneration. Knee Surg Sports Traumatol Arthrosc. 2015 Jan;23(1):188-97. doi: 10.1007/s00167-014-2997-2. Epub 2014 May 4. PubMed PMID: 24792070.