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Purpose of Review: Traumatic and nontraumatic patellofemoral instability (PFI) in children and adolescents is a complex problem. It is determined by a large number of mechanical and pathomorphologic conditions, mainly seen in nontraumatic dislocations., Recent Findings: Although conservative treatment with a short immobilization, followed by early passive motion and isometric quadriceps strengthening, can be considered in real traumatic dislocations without any cartilaginous injury, a surgical intervention should be considered in atraumatic cases. As 90% of PFI are nontraumatic and correlated with skeletal deformities, the redislocation rate is reported to be up to 80% after initial conservative treatment. To optimize the results, the causing disorder for PFI has to be considered imperatively. In addition to bony disorder, further risk factors have to be taken into consideration for determining the optimal time for surgery. As biomechanical and clinical studies have shown the importance of the medial patellofemoral complex, especially the medial patellofemoral ligament (MPFL), against patellar lateralization, the reconstruction or minimally invasive double-bundle reconstruction of the MPFL is the main surgical technique to treat PFI in children, as it can be used even in open epiphysial cartilage. Further surgical interventions correcting bone deformities, such as trochleoplasty or tibial tubercle osteotomies addressing lower limb deformities, should be performed after closure of the epiphysial cartilage., Summary: It is the goal of this overview to explain the pathoanatomy of PFI, the demanding clinical and radiological examinations and treatment options.

Traditional techniques for restoration of a separated acromioclavicular joint are afflicted with various complications and often lead to recurrent dislocation. Lately, anatomic as well as minimally-invasive repair techniques with major focus on restoration of the coracoclavicular ligaments have been described for acromioclavicular joint reconstruction. We present a technique for an arthroscopically-assisted anatomical acromioclavicular joint reconstruction by replacing the conoid and trapezoid separately with nonabsorbable sutures and titanium buttons.

CT scan is the gold standard for the measurement of the tibial tuberosity-trochlear groove distance (TTTG). The aim of this study was to evaluate the reliability of the TTTG on MRI compared to CT scan. Twelve knees in 11 patients underwent CT and MRI examination for patellofemoral instability or anterior knee pain. Both the bony and the cartilaginous landmarks of the trochlear groove were used for the measurement of the TTTG. The measurements were performed by two experienced musculoskeletal radiologists. The interrater, intermethod and interperiod reliability was calculated using a restricted maximum likelihood estimation and a Bland-Altman analysis. The mean TTTG referenced on bony landmarks was 14.4+/-5.4 mm on CT scans, and 13.9+/-4.5 mm on MR images. The mean TTTG referenced on cartilaginous landmarks was 15.3+/-4.1 mm on CT scans, and 13.5+/-4.6 mm on MR images. An excellent interrater (82%), intermethods (86%), and interperiod (91%) quantitative reliability was found. TTTG can be determined reliably on MRI using either cartilage or bony landmarks. Additional CT scans are not necessary.

Complex two-level rotational malalignment of the lower extremity can cause maltracking of the patella with anterior knee pain. Double derotation osteotomy would correct the underlying pathology. However, it carries a high risk of complications such as nerve and vessel damage. We report a case of rotational malalignment in the femur and the tibia associated with trochlear dysplasia, which causes painful patellar instability. The patient was successfully treated with reconstruction of the medial patellofemoral ligament and lateral release. Although the malrotation was not addressed, the position of the patella was corrected, and no dislocation occurred during a follow-up of 10 months.

Goal: The failure load of the SD meniscal staple was compared with the 2-0 Etibond meniscus suture in a dynamic test without isolating the meniscus., Methods: In eight knee joint pairs, a standardized lesion of the posterior part of the medial meniscus was repaired by either three staples (7 mm) or three 2-0 Etibond sutures. After resection of the cruciate ligaments and 15 degrees external rotation, 45 degrees flexion, and 70 kg of axial loading, a tibial translation was exerted on the knee joint. The test was documented on a way force diagram, demonstrating the failure of the device at a sudden load of force., Results: The average load before failure of the meniscus staple was 591.2 N (540-690 N), that of the sutures 850 N (600-1350 N). We did not find any statistical correlation to age,weight, or height of the specimens. The suture migrated, but never ruptured. In two cases the suture caused a radial meniscus lesion. Failure of the staple was detachment of the inferior part in all cases, but no migration., Conclusion: This test is based on the dynamic forces of the knee joint on the meniscus. Our measurements show lower failure loads of the staple compared to those of the sutures, but compared to other tests a stable method of meniscus repair.

Therapy of cartilage damage is a frequent problem, especially in the young and active patient. For the treatment of a cartilage damage we have to consider the size of the defect, age and weight of the patient, meniscal tears, ligament instabilities and varus-/valgus-malalignment. Lavage, shaving and debridement are only sufficient for a short time and have no long term effect. Abrasio and drilling could be useful in eldery people. Microfracturing seems to be an effective alternative for small defects. The restoration of the cartilage surface with the use of autologous chondrocyte transplantation, osteochondral autograft transplantation and posterior condyle transfer seems to be an adequate treatment for younger patients.