For 32-year-old Kathryn Xakellis, ACL injuries weren’t just a one-time setback. They set her on a decade long journey that gave her a unique perspective on recovery. She first tore her anterior cruciate ligament (ACL) in her left knee during an intermural soccer game in 2014 and underwent a traditional ACL reconstruction (ACLR) with a cadaver graft. Fast forward 10 years, and she tore the ACL in her right knee – which is called a contralateral tear – and decided to talk to her godfather and orthopedic surgeon Dr. Mark Perezous at Lancaster Orthopedic Group in Lancaster, Pennsylvania, to see what other medical advancements were now available. Although she recovered well following ACLR, she knew firsthand how challenging and painful the process could be and decided to choose the BEAR Implant to treat the ACL tear on her right knee.

We spoke with Kathryn and Dr. Perezous about why the BEAR Implant was a good fit, her rehab journey following both ACLR and BEAR Implant surgery, how the BEAR Implant helped her discover a love for HYROX, an indoor fitness race combining 8 km of running with eight functional workout stations, and how she’s doing today 3 years post-surgery.

Q: Tell us about your two ACL injuries. How did they happen?

Kathryn: The first time I tore my ACL on my left knee was back in 2014 while playing a game of intermural soccer in college. While I was chasing after a ball, I planted too hard and my knee gave out. I cried and screamed from the pain; it was that bad. My knee got really swollen, and I had to get it drained before I could even get an MRI to confirm an ACL tear. Dr. Perezous was unable to do my surgery at the time, so he referred me to another doctor who suggested ACL reconstruction using my own ligaments or using a cadaver. Since I wanted the least amount and least invasive surgery possible and knew I wasn’t going to return to playing full on soccer again, I went with the cadaver.

Eight years later, I decided to play soccer for fun on a co-ed team. I figured there’s no way I would tear my ACL again. While playing the last game of the season, I heard a crunch in my right knee during a move, my knee immediately started to swell up and I couldn’t walk by the next day. It gave me flashbacks to my previous ACL injury. Once I got the MRI to confirm I tore my ACL in the opposite knee, I was so bummed.

Q: How did you learn about the BEAR^® Implant and why did you select it to treat your second ACL tear?

Kathryn: When I went to see Dr. Perezous after my ACL tear in the opposite knee was confirmed, he mentioned that there was a newer procedure called the BEAR Implant where I wouldn’t have to get a cadaver again or even use one of my own ligaments. He told me I would be able to heal my original ACL, and I was sold. In addition to being a great surgeon, Dr. Perezous also happens to be my godfather. This added another level of trust for me, because he was familiar with the level of activity I wanted to return to and also wouldn’t steer me in a direction that wouldn’t be a good fit. He also told me that this procedure would likely be less painful than ACLR. It sounded a lot more palatable to me given how much pain I was in after my original surgery – I did not want to go through that again.

To be able to put the BEAR Implant in my knee and use my own tissue and blood to heal my ACL was extremely cool. I was excited to try it because it was a medical advancement that was not available to me a decade ago, so I was like “sign me up!”

Q: What, in your opinion, is most notable about the BEAR Implant? 

Dr. Perezous: The BEAR Implant is the most exciting Sports Medicine innovation that I have seen in my 31-year career. I have performed approximately 50 BEAR Implant surgeries to date. Being able to preserve native tissue and stimulate the ACL to heal while maintaining proprioception, your body’s ability to sense its own position and movements, is remarkable. In addition, no bridges are burned if further surgery is needed in the future. Now we have evidence of decreased risk of post traumatic arthritis, which is a game changer. Certainly, utilizing autografts is not without postoperative risks, including persistent knee pain and weakness

Q: Why was Kathryn a good candidate for the BEAR Implant?

Dr. Perezous: Kathryn had a traditional reconstruction on her contralateral knee. She was intrigued by the BEAR Implant and had pretty much shifted her sports emphasis to training as compared to her prior collegiate soccer career.

Q: Can you compare how you felt after your first ACL reconstruction to your BEAR Implant procedure?

Kathryn: After my initial ACL reconstruction back in 2014, I was in so much pain. I almost passed out from the pain after taking off my knee brace for the first time. After a few weeks, the pain slowly started to dissipate, but the first couple months of rehab were still very challenging. I was surprised by how hard it was. It felt weird even trying to move my knee because it felt like a brand-new ligament with the cadaver, and it needed to be stretched and adjusted to fit my body.

I was shocked at how little pain I was in 24 hours after getting the BEAR Implant. I didn’t even need to take pain medication! While moving my knee for the first time at my initial physical therapy appointment post-BEAR, I had very minimal pain. I told my mom afterward how crazy it felt to not be in pain and actually able to move my leg so quickly after surgery. It was pretty amazing how good I felt after the BEAR Implant compared to my previous experience.

Q: Tell us about how BEAR Implant rehab went.

Kathryn: What was most challenging for me was the mental side of rehab versus the physical side. Compared to ACLR rehab, you aren’t progressing as quickly as you do in the beginning, so I needed to get used to that. After a couple weeks, the physical therapy exercises started to become second nature, and it was easy to learn how to maneuver around.

Since my second ACL tear was on my driving leg, it was really tough for me. I appreciated my physical therapist encouraging me to follow the strict rehab protocol those first couple months. She explained that it wasn’t like I was stretching out a new ligament like ACLR with a cadaver the first time, but I was actually healing my ACL. Once I came to terms with that, I locked in on accepting that whatever I was able to do, I would really focus on it. During my rehab this time, I worked on keeping other parts of my body like my arms and abs healthy. I appreciated how thoughtful the BEAR Implant rehab protocol booklet was – it helped to know what milestones were coming up. I started to feel a lot better and stronger at the 4-month mark with the BEAR Implant compared to ACLR with the cadaver. I was fully cleared to return to sport at the 9-month mark, the same timeline I was cleared to return to sport following ACLR surgery.

Dr. Perezous: She had excellent recoveries for both knees, but her BEAR Implant was exceptionally smooth.

Q: How has the BEAR Implant technology impacted how you treat ACL tears?

Dr. Perezous: The BEAR Implant is generally my first option. I will pivot to a reconstruction if there is inadequate tissue for the BEAR Implant. My patients are very excited about it also.

Q: Can you tell us about why you decided not to return to soccer and how you became interested in HYROX?

Kathryn: I played soccer competitively for 15 years without any serious injuries. I decided to quit once I was a junior in college, and then I tore my ACL 2 months later while playing soccer for fun. When I tore my ACL again in the opposite knee while playing soccer for fun again, I decided that my ACL was telling me enough was enough. I retired from playing soccer fully after recovering from the BEAR Implant and started to do CrossFit. Although I was gaining a lot of muscle, I missed the cross-training feeling and intensity I used to have with soccer. That’s when I discovered HYROX, which combines running, cross-training and competitions. It really gave me accountability to train for HYROX competitions with a partner, and I completed my first in 2025 and my second in 2026. I would equate HYROX to training for marathons; each race consists of an 8 km (~5 mile) run and 8 stations including lighting and rowing.

Q: Can you tell us about competing in HYROX after you were cleared to return to sport?

Kathryn: Mentally at the 9-month mark, I felt confident in my knee. I wasn’t thinking about my BEAR Implant knee, but I was more worried about my ACLR knee due to an increase in running for HYROX training. I would have to tape up my ACLR knee for more support. At my first post-rehab competition, I had no knee pain, and I completed the race in 1 hour and 26 minutes, placing in the middle amongst 700 people.

Q: How does your BEAR Implant knee feel today compared to your ACLR knee?

Kathryn: Both of my knees feel fine, but now that I’ve started to train harder and run more for my HYROX races, I do notice that my ACLR knee is bothering me a lot more than my BEAR Implant knee. It’s definitely still giving me some more pain than I thought it would at this point in my life 10 years post-surgery. The pain doesn’t stop me from doing physical activities, but I notice a lot more soreness in my ACLR knee after anything high impact.

In comparison, my BEAR Implant knee feels completely normal regardless of what physical activity I do. I literally don’t even feel like I had an ACL repair or any surgery at all. Even my scars on my BEAR Implant knee are minimal compared to the ACLR knee, which is nice. I don’t think about my BEAR Implant knee at all anymore, and it hasn’t let me down yet in the past three years, so I’m pretty happy.

Q: What unique considerations are there for athletes like Kathryn when it comes to the BEAR Implant vs. ACLR?

Dr. Perezous: The BEAR Implant is still a relatively new technology, and until we have further studies, which are ongoing, ACLR will still be considered the gold standard. Certainly, some of the studies suggest that we could have a new standard of care.

Q: What advice would you give to other patients who’ve torn their ACL?

Kathryn: Don’t play soccer! Just kidding, but honestly, I would suggest the BEAR Implant if you’re a candidate for it. It’s a very niche conversation, but for people who’ve torn their ACLs more than once – it may not be known how painful ACLR surgery can be. If there’s any way to cut down on post-surgical pain, why not? Being able to heal my own ACL with the BEAR Implant in a more natural way without having to mess with other parts of my body or inserting a foreign ligament has been amazing.

Q: What are some of your future goals?

Kathyrn: I want to get my one-mile time down to 8 minutes and 30 seconds for HYROX. From a race standpoint, my goal is still to place in the middle of the pack. I’m planning to run a 5K, followed by a 5-mile race – culminating in competing in the HYROX competition in D.C. in 2027.

Learn more about the BEAR Implant and find a surgeon

The BEAR Implant is available across the U.S. Learn more about the BEAR Implant or find a surgeon in your area. If you’re a parent considering the BEAR Implant for your child, click here for more information. If you’re a BEAR Implant patient and would like to share your story, click here.

The BEAR Implant from Miach Orthopaedics was approved by the U.S. Food and Drug Administration in December 2020. It is indicated for adults, adolescents and children with a complete or partial rupture of the ACL, as confirmed by MRI. Patients must have an ACL stump attached to the tibia to construct the repair. Children with open physes must have sufficient bone in the femoral and tibial epiphyses on either side of the intended tunnel locations to avoid disruption of the growth plates. In patients 14 years and older who have an ACL injury with concomitant knee injuries, ACL restoration with the BEAR Implant reduces the risk of developing post-traumatic knee osteoarthritis (Kellgren-Lawrence grade 2 or higher), at 6-years post-surgery, compared to ACL reconstruction (ACLR) surgery using hamstring tendon autograft.

It is important to follow the BEAR Implant physical therapy program. Your surgeon can explain the program details.

Be sure to discuss your individual symptoms, diagnosis and treatment with your surgeon. The BEAR Implant has the same potential medical/surgical complications as other orthopedic surgical procedures, including ACL reconstruction. These include the risk of re-tear, infection, knee pain, meniscus injury and limited range of motion.

Visit miachortho.com for complete product information, including Instructions for Use.

ML-1404 Rev A 07/2026