Risk of Patellar Tendon Rupture After 5 Years Post-BPTB ACL Reconstruction
Patellar tendon rupture after BPTB ACL reconstruction is an extremely rare complication, with the vast majority of cases occurring in the early postoperative period (6-10 weeks), and the risk becomes negligible after 5 years when the donor site has fully healed and remodeled. 1, 2
Timing and Incidence of Rupture
The critical window for patellar tendon rupture is during the first 2-3 months postoperatively, not at 5 years:
- Early rupture risk (6-10 weeks): Case reports document patellar fractures and tendon ruptures occurring during rehabilitation between weeks 6-10 post-surgery, when patients are performing eccentric knee extensions or maximal voluntary isometric contractions 2
- Late rupture risk (5+ years): There is no documented evidence in the literature of patellar tendon ruptures occurring 5 years after BPTB ACL reconstruction when the donor site has fully healed 3
Long-Term Outcomes at 5 Years
At the 5-year follow-up mark, the primary concerns are not rupture but rather functional outcomes:
- No structural complications: A prospective study following 68 patients (34 BPTB, 34 hamstring) found no patellar tendon ruptures at 5-year follow-up, with equivalent anterior knee laxity, rotational stability, and hop performance between groups 3
- Anterior knee pain: The AAOS guidelines recognize that BPTB grafts may increase anterior or kneeling pain compared to hamstring grafts, but this is a chronic symptom rather than a rupture risk 1
- Re-rupture concerns: The actual concern at 5 years is ACL graft re-rupture (10.2% in one study) or contralateral ACL injury (5.9%), not patellar tendon rupture 3
Why the Risk is Negligible at 5 Years
The biological healing timeline explains the absence of late ruptures:
- Donor site remodeling: By 5 years post-surgery, the patellar tendon donor site has undergone complete healing and remodeling, restoring structural integrity 1
- Strength recovery: Quadriceps strength deficits normalize over time, and patients at 5 years have regained functional muscle performance 3
- Activity level stabilization: While patients may not return to pre-injury sport levels (a common finding at 5 years), those who do are not experiencing patellar tendon ruptures 3
Clinical Pearls for Risk Mitigation
If you are evaluating a patient 5 years post-BPTB reconstruction with concerns about donor site integrity:
- Focus on current symptoms: Assess for chronic anterior knee pain or patellofemoral dysfunction rather than rupture risk 1
- Evaluate for graft failure: If the patient has new instability, consider ACL graft re-rupture (which has a documented 10% risk) rather than patellar tendon issues 3
- No special precautions needed: Patients at 5 years do not require activity restrictions related to patellar tendon rupture risk, as the donor site is fully healed 1, 3
Common Pitfall to Avoid
Do not confuse the early postoperative rupture risk (weeks 6-10) with long-term risk. The documented cases of patellar fracture and tendon rupture all occurred during the vulnerable early rehabilitation phase when aggressive quadriceps strengthening was initiated before adequate donor site healing 2. This risk does not persist to 5 years.