When Mike Brennan’s knee gave out under the weight of two falling training partners during a Krav Maga session, he heard the dreaded pop and instantly knew something was very wrong. In a split second, Mike went from an active lifestyle logging 30+ mile trail runs to wondering if his athletic life was over for good.

At 40 years old, with a completely torn ACL, a near-complete MCL tear, and meniscus damage, the path forward wasn’t obvious. Traditional surgical options came with tradeoffs he wasn’t sure he could accept. Mike sought out Dr. Kai Mithoefer, an orthopedic surgeon at Boston Bone & Joint Institute in Boston, Massachusetts, and was introduced to the BEAR Implant. We spoke with Mike and Dr. Mithoefer about why Mike chose the BEAR^® Implant, the comparison between the physical vs. mental aspects of rehab and his return to running ultramarathons.

Q: How did you tear your ACL?

Mike: I was working with my partner on a drill in Krav Maga class. Two other guys working next to us got tangled up and crashed into my right knee. I heard a big pop, felt instant pain and crashed to the mat. I got an MRI the next morning, which confirmed I completely tore my ACL as well as a near complete MCL tear and meniscus tear.

Q: How did you learn about the BEAR Implant and decide it was the right option for you?

Mike: Initially, my primary care physician didn’t recommend surgery given I was already 40 years old. I wasn’t done running or doing Krav Maga, so not having surgery wasn’t an option for my active lifestyle. I met with two orthopedic surgeons – one who recommended traditional ACL reconstruction (ACLR) and Dr. Mithoefer, who introduced me to the BEAR Implant. My wife works in healthcare and sent me a lot of research on the procedure. After reading through it all, we decided it was the best option for me. I was really drawn to the fact that it would heal my original ACL, and I wouldn’t have to get a cadaver ligament or take a quad or patellar tendon from my own body. I’ve had friends who had ACLR with quad grafts and they never really felt the same even after they recovered.

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

Dr. Mithoefer: The BEAR Implant allows for restoration of the native ACL which offers multiple significant anatomic and biomechanical benefits compared to ACLR. Most importantly, recent data shows that ACL restoration with the BEAR Implant significantly reduces the incidence of post-traumatic knee arthritis compared to ACLR.

Q: Why was Mike a good candidate for the BEAR Implant and why do you recommend it for patients like him?

Dr. Mithoefer: Mike had a so called “proximal ACL tear,” where the ligament is pulled off its femoral attachment. This tear configuration largely preserves the ligament’s structure, creating the ideal setting for anatomic ligament restoration and normal postoperative joint function.

In my opinion, the BEAR Implant currently provides the most anatomic and biomechanical restoration of the knee joint after ACL injury. For active individuals like Mike, this surgical technique, combined with appropriate postoperative rehabilitation, offers one of the best options for returning to their sports activities.

Q: How did you get into ultramarathons?

Mike: I ran a lot for fun when I was younger, and in 2019, I read a book by Scott Jurek, a famous ultramarathon runner. I was very interested in this niche and decided to train for a 50K (31 mile) race the following year. I fell in love with ultramarathons because they have helped me understand how the brain and body work together to protect you when running such long distances.

Q: Did you ever think you might not return to sport?

Mike: Absolutely. I was 40 when I tore my ACL and I thought it might have been the end of my sporting career. I had never been seriously injured and the idea of going through rehab was daunting.

Q: Tell us about the rehab experience.

Mike: Rehab went well. What I discovered through the physical therapy (PT) process, is that my body is a little bit slower to get started – especially during the prehab before surgery and in terms of getting range of motion back. It took me a little bit longer than I expected to hit certain benchmarks. Once I started to pick up steam, I caught up with the rehab schedule. The mental aspect of rehab was difficult because I could no longer run – and running was something that I had come to rely on, both as a sport I love and also as a coping mechanism for life stress.

I actually sought out a sports psychologist to help me through those initial phases of understanding I was still who I was. I had to work through feelings of being attached to my sport as my identity and knowing that wasn’t really true. Going to therapy after a physical injury is one of those things that probably doesn’t get talked about enough. Athletes with injuries and people in general should know that it’s okay to grieve that loss and know that if you feel the need to talk to someone professionally about it, you should.

Dr. Mithoefer: Mike participated regularly in PT and had a very active recovery, rapidly progressing athletic activities by returning to running at 4 months and martial arts at 5 months. He has excellent knee stability and function and continues to participate in his athletic activities without limitations.

Q: What unique considerations are there for athletes like Mike?

Dr. Mithoefer: Mike participates in competitive, high-impact sports like ultramarathons which place ultra-high mechanical loads on the knee joint surface. In the setting of Mike’s continued ultramarathons, the significantly reduced post-traumatic arthritis rate after BEAR Implant compared to ACLR is critically important so Mike can safely continue his beloved sport without risking rapid joint degeneration. Mike’s story is not unusual. I have observed similar outcomes in the many of my patients treated with the BEAR technique.

Q: Can you tell us about your return to sport?

Mike: I was cleared to return to sport at 11 months post-surgery. My first run back was a 13-mile training run to train for my first planned ultramarathon with the BEAR Implant. It was a beautiful day and everything seemed to go right. Instead of taking my headphones with me like I normally do, I felt free and immersed in the woods near my home. I was very confident in my knee, so I went and hit some of the harder trails without issue.

Q: How was running your first ultramarathon post-surgery?

Mike: My first ultramarathon with the BEAR Implant was a charity event I planned as the race director. We set up a 1K loop, and I ended up running 50 loops that day. After completing the race with no issues, I knew I could run more. The next race was an ultramarathon in the fall. Ultramarathons typically require a lot of preparation to know what you want to do at specific points in this race. However, since I had such a good experience at the charity run, I didn’t want to plot the course too heavily and decided to just see how the day unfolded.

My loose plan was to complete it in 5 hours and everything just clicked. I kept waiting for little signals of the wheels starting to fall off, but they never really came. My knee felt great and I was able to finish the race faster than I had previously – completing 30 miles in 4 hours and 45 minutes. I was really proud of all the work I put in to be able to come back and compete at that level.

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

Dr. Mithoefer: Based on the excellent outcomes I have observed in the more than 100 patients I have treated with the BEAR Implant to date, I have started to recommend BEAR as a primary treatment option for ACL tears in all my eligible patients.

Q: Have you observed anything new about the BEAR Implant in your most recent cases?

Dr. Mithoefer: I typically use an internal brace augmentation during the BEAR procedure. This enhanced surgical technique allows for much more proactive postoperative rehabilitation, eliminating the need for crutches and enabling a faster return to activities.

Q: Would you recommend the BEAR Implant and do you have any advice for others who have torn their ACL?

Mike: I would absolutely recommend the BEAR Implant for people like me who are motivated to get back to their previous activity level. My advice to others is to do all of the boring work. There will be times during your rehab and your prehab where progress is slow and you may wonder why you’re doing these exercises. Continue to do what’s asked of you at the pace you’re given because it will make all the difference in the end.

Q: How does your BEAR Implant knee feel today?

Mike: My BEAR Implant knee feels great, and I don’t notice any big distinctions between it and my non-injured knee. I have 100% confidence in my knee and everything it needs to do. I’m right back to where I was pre-injury in terms of workouts and day-to-day life.

Q: What are your long-term goals with ultramarathons? 

Mike: I have a couple of adventures planned this year, including a 30-mile loop in New Hampshire with a high elevation gain. I’ve run 15 ultramarathons since 2020, and I plan to continue to run two races a year. Aside from running, I also started coaching endurance runners and tailor training long distances for them. I have a greater respect for what people coming back from injury are facing. I hope to continue sharing my experience to help others.

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.

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