The risk of graft impingement still exists in modern ACL surgery and correlates with degenerative MRI signal changes.

PURPOSE: Anatomic tunnel placement in ACL reconstruction is crucial to restore knee function. The aims of this study were to (i) evaluate the accuracy of tunnel placement for primary state-of-the-art ACL reconstruction, and (ii) examine the correlation between incorrect tunnel placement, graft appearance, and notch impingement. METHODS: In this retrospective study, all patients underwent primary single-bundle ACL reconstruction with independent drilling of the femoral and tibial tunnels according to anatomical landmarks. The accuracy of tunnel placement and the rate of notch impingement were analysed with MRI. The study cohort was subdivided according to the morphology of the graft: intact, degeneration, and re-rupture. The objective outcome was evaluated with the IKDC objective score, and the subjective outcomes were evaluated with the IKDC subjective score, the Lysholm knee score, the KOOS, and the Tegner activity scale score. RESULTS: Eighty-seven consecutive patients with a mean follow-up of 3.8 ± 1.4 years were evaluated. There was no significant difference among the groups concerning the baseline characteristics. The re-rupture rate was 9.2%. The position of the femoral tunnel was correct in 92% of the patients, and the position of the tibial tunnel was correct in 93% of the patients. In the intact group, impingement was not found in any of the cases, whereas the rate of impingement in the degeneration (65%) and re-rupture (80%) groups was significantly higher than that in the intact group (p < 0.001). The risk of impingement was more likely with femoral (71% vs. 13%, p < 0.001) or tibial (100% vs. 11%, p < 0.001) malpositioning. The objective IKDC score was A in 52 patients (60%), B in 26 patients (30%), and C in 9 patients (10%). The average subjective IKDC score, Lysholm score, and KOOS were comparable in the intact and degeneration groups but significantly lower in the patient group with newly diagnosed re-ruptures (p = 0.05). The Tegner activity scale score was comparable in all three groups. CONCLUSION: Even though the accuracy of femoral tunnel placement in modern single-bundle ACL reconstruction is greater, the risk of malpositioning and graft impingement remains. In our patient cohort, there was a clear correlation between ACL graft impingement, degenerative changes in MRI, and incorrect tunnel positioning. The surgeon must focus on accurate tunnel placement specific to individual patient anatomy. LEVEL OF EVIDENCE: Level III.

[Patellofemoral instability in children and adolescents]. / Patellofemorale Instabilität bei Kindern und Jugendlichen.

Dislocation of the patella is one of the most common knee injuries in childhood and adolescence. After detailed clinical and radiological clarification, conservative functional treatment with special orthotic devices is most commonly applied in patients with a primary dislocation without concomitant injuries; however, the redislocation rate after conservative treatment has been reported in the literature to be between 35% and 70%, depending on the risk factors present. Therefore, numerous surgical treatment options exist which are sometimes again associated with high redislocation rates and others can lead to early arthrosis of the patellofemoral joint when used indiscriminately. Many scientific contributions on the topic notably in the last two decades have increased the understanding of patellofemoral instability. The comprehensive knowledge of the causes for a persisting instability of the patella has made the treatment more efficient and precise but also more complex.

Non-union site debridement increased the efficacy of rhBMP-2 in a rodent model.

In our study we investigated the influence of debridement on bone healing in a rodent critical size defect model with and without rhBMP-2 in fibrin matrix. A total of 58 male Sprague-Dawley rats underwent a first surgical procedure where a femoral osteotomy was performed. In the single step group the defect remained empty and the specimens were collected 4 weeks later. A silicone spacer was implanted to inhibit bone healing within the defect in all the other groups. At 4 weeks the spacer was removed in a second operation with and without debridement of the bone ends and fibrin matrix alone or combined with 10 µg rhBMP-2 were applied. 4 weeks after the primary operation those specimens were collected. All the specimens were evaluated by µCT scans and histological analysis. Debridement of the defect significantly increased bone volume in the animals treated with rhBMP-2. In the control groups without growth factor application the effect of debridement was not significant concerning the union rate and the bone volume. In our experimental setting surgical debridement of the non-union site particularly promoted bone healing in combination with BMP-2 administration in fibrin matrix.