When reconstructing the anterior cruciate ligament (ACL) alongside the anterolateral ligament (ALL), getting the ALL femoral positioning right directly determines how well the knee resists rotational instability after surgery. Surgeons have traditionally relied on finger palpation to locate the lateral femoral epicondyle (the bony landmark used as a reference point), but a rigorously designed cohort study challenges whether that approach is consistently reliable.
Published in a peer-reviewed journal, the study Femoral Positioning of the Anterolateral Ligament Graft With and Without Ultrasound Location of the Lateral Epicondyle, conducted with the involvement of Professor Cavaignac, provides compelling data on the benefits of ultrasound guidance for ALL graft positioning. This article offers a summary of its key findings.
Why does ALL graft positioning matters in ACL reconstruction?
Combined ACL and ALL reconstruction has become an increasingly adopted technique for patients with high rotational instability, particularly those returning to pivoting sports. The ALL is a ligamentous structure on the outer side of the knee that resists internal tibial rotation. During ACL surgery, the ALL graft is anchored at two points: on the tibia and on the femur. The femoral attachment is typically placed just posterior (behind) and proximal (above) to the lateral epicondyle, a small bony prominence on the outer part of the lower femur.
Getting this position right matters because a graft placed too far forward or too low can become tight in flexion, potentially limiting knee movement or accelerating graft failure. Reproducibility (achieving the same correct position reliably across patients and surgeons) is therefore a core quality indicator for this procedure. The study referenced here set out to measure exactly that.
Palpation vs ultrasound, how the study was designed
120 patients underwent primary combined ACL and ALL reconstruction and were split into two equal groups:
- Palpation group (n = 60): the lateral epicondyle was located by touch alone.
- Ultrasound group (n = 60): preoperative ultrasound guidance was used.
Groups were matched for age, sex, BMI, and operated side. Postoperative lateral X-rays were then used to assess whether the femoral ALL graft had landed within the target zone: a 10 mm quadrant posterior and proximal to the lateral epicondyle.
Key results: a clear difference in accuracy
| Group | Grafts correctly positioned | Accuracy rate |
| Ultrasound guidance | 60/60 | 100% |
| Palpation alone | 52/60 | 87% |
The difference between the two groups was statistically significant (P = .006). Every single graft in the ultrasound group landed within the target quadrant, compared to 87% in the palpation group — meaning 8 patients in the palpation group had a femoral graft positioned outside the intended zone.
Importantly, positioning errors with palpation were not limited to overweight patients. Errors occurred in patients with a BMI above 25 as well as those below, and the difference between these BMI subgroups was not statistically significant (P = .3). This finding suggests that body composition does not explain the inaccuracy — the limitation appears to be inherent to tactile localisation itself.
For a detailed breakdown of graft deviation distances and subgroup data, the full study provides the complete dataset.
What this means clinically
The findings have a straightforward implication: using ultrasound to locate the lateral epicondyle before performing anterolateral ligament reconstruction improves the reproducibility of femoral graft placement, regardless of the patient’s body type. A 13% error rate with palpation may seem modest, but in the context of a ligament reconstruction where millimetres affect biomechanical outcomes, it is clinically meaningful.
Adding a preoperative ultrasound step is a relatively simple adjustment to surgical planning. For surgeons performing a high volume of combined ACL/ALL procedures, the data suggest this step is worth adopting systematically.
This study represents one part of an ongoing body of work on anterolateral ligament reconstruction. To explore the broader research from Professor Cavaignac’s team, including related studies on ALL anatomy, tibial positioning, and surgical outcomes, the other scientific publications available on this site are worth reading.
Conclusion & Findings
This study provides clear evidence that ultrasound-guided localisation of the lateral epicondyle improves the reproducibility of ALL femoral graft positioning compared to palpation alone, with a 100% accuracy rate versus 87%. The benefit holds regardless of BMI, which strengthens the case for adopting this technique as standard practice in combined ACL/ALL reconstruction.
Professor Cavaignac is a knee surgeon with a particular focus on ligamentous reconstruction and research. If you are considering consultation or simply looking for evidence-based information on knee surgery, feel free to contact him directly.