Risk of Patellar Tendon Tear Following Bone-Patellar Tendon-Bone ACL Reconstruction
The risk of patellar tendon tear following bone-patellar tendon-bone (BPTB) ACL reconstruction is low, with an incidence of approximately 0.24% based on clinical evidence. 1
Incidence and Risk Factors
- Patellar tendon ruptures are rare complications after ACL reconstruction using BPTB autografts, occurring in less than 0.5% of cases 1
- Most tears occur within the first few months after surgery, with a mean occurrence time of approximately 57 days post-surgery 2
- Tears can result from both direct trauma to the knee and indirect forces during rehabilitation exercises 2
Common Tear Patterns
- The most common tear pattern (approximately 54% of cases) is a Z-shaped pattern with rupture from the patellar origin medially and the tibial attachment laterally 1
- Other patterns include completely distal tears (31%) and completely proximal tears (15%) 1
- These patterns differ from the typical proximal-only tear pattern commonly observed in unharvested patellar tendons 1
Risk During Rehabilitation
- Patellar fractures, which can lead to tendon damage, have been reported during rehabilitation exercises, particularly during:
- The risk period extends throughout early rehabilitation, with documented cases occurring as late as 10 weeks post-surgery 3
Management Considerations
- When patellar tendon tears do occur, they can be managed both operatively and non-operatively depending on the severity 4, 1
- Partial tears without extensor mechanism incompetence or significant patella alta may be treated non-operatively with good outcomes 4
- Complete tears typically require surgical repair, often using suture anchors and cable augmentation 1
Long-term Outcomes
- Despite the initial complication, patients with repaired patellar tendon tears can achieve good functional outcomes 1, 2
- Studies show that 75% of patients with postoperative patellar fractures achieved excellent or good Lysholm scores 2
- Most patients regain full flexion compared to the contralateral knee, though some may have minor limitations in hyperextension 2
- Quadriceps strength can return to 100% of the contralateral side with appropriate rehabilitation 1
Prevention Strategies
- The American Academy of Orthopaedic Surgeons (AAOS) guidelines recognize that BPTB autografts have advantages in reducing graft failure risk but may increase anterior or kneeling pain compared to hamstring grafts 5
- Careful attention to surgical technique during graft harvest is essential to minimize complications 6
- During rehabilitation, clinicians must balance competing goals of improving quadriceps strength while protecting the donor site 3
- Early mobilization should be implemented with caution, monitoring for signs of donor site pain or weakness 5
Clinical Decision Making
- For patients at higher risk of complications (older, less active), non-surgical management of ACL tears may be appropriate 5
- For younger, active patients requiring reconstruction, the choice between BPTB and hamstring autografts should consider the relative risks and benefits 5
- When BPTB grafts are used, rehabilitation protocols should include specific protection strategies for the donor site 5