In 2023, Notus Labs partnered with the orthopedic surgery department at Case Western Reserve University to answer a question that functional testing alone couldn't close: what does biomechanical recovery actually look like between clinical visits?
The partnership produced the first longitudinal biomechanical monitoring study on post-ACL reconstruction patients. Sixty patients. Twenty-four weeks of continuous sensing. One shared hypothesis.
The findings reshaped how we think about the clearance window — and how Case Western thinks about return-to-play decisions.
The partnership
Case Western Reserve brought what academic orthopedic programs do best: rigorous study design, IRB oversight, and a surgeon-led clinical cohort that reflected real-world post-ACL patients rather than an idealized subset.
Notus Labs brought continuous biomechanical sensing — the Notus Labs armband worn 18+ hours daily, streaming gait, load, and motion data through every week of the recovery window.
The study
Sixty patients enrolled between surgery and week two of rehab. All post-ACL reconstruction. Mixed primary and revision cases. Mixed graft types.
Continuous biomechanical sensing for 24 weeks through the Notus Labs armband. Standard clinical milestones at weeks 8, 12, 16, 20, and 24. No changes to the rehab protocol itself — the study was observational.
The question was simple: what would continuous data reveal that standard clinical exam couldn't?
What we found
At week 8, nearly 40% of patients showed persistent inter-limb loading asymmetry in the motion data — 12 to 18% higher load on the contralateral limb — despite appearing on-schedule in clinical exam.
By week 16, most patients were passing traditional functional tests. But motion data showed that compensation patterns re-emerged under increased training load, and that valgus collapse persisted in cutting movements for many patients well past week 24.
Patients cleared by both continuous data and clinical exam returned to play, on average, 76% faster than the pre-study Case Western cohort — and with no reinjuries in the following 18 months of follow-up.
Standard exam captured 20 minutes of controlled movement every two weeks. The sensor captured 18 hours a day. Those are different datasets — and the second one changed our clearance thinking.
What the Case Western partnership changed for both teams:
- Continuous monitoring became a clearance prerequisite, not a supplementary signal
- The biomechanical recovery window expanded from 9 months to 12–18 months in practice
- Week-8 compensation patterns became an intervention trigger rather than an observation
- Valgus-under-fatigue testing entered the standard clearance panel
- De-identified cohort data began flowing back into the academic literature
The partnership continues. A second cohort is now at month 18 of follow-up, and the protocol changes that came out of the first study are in use across every research program on the Notus Labs platform.
Case Western remains our closest research partner — the institution that turned continuous biomechanical monitoring from a research hypothesis into a clinical practice.
