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Quantification Of Trochlea Dysplasia Via Computed Tomography: Assessment Of Morphology Difference Between Control And Chronic Patellofemoral Instability Patients
Objectives: Trochlear dysplasia is an important risk factor for the development of recurrent patella instability. Owing to its complex 3-Dimensional morphology, the need for a true lateral radiograph, and poor inter-observer reliability, the Dejour classification system of dysplasia may not be the most optimal measure for quantification. The purpose of this study is to report a novel technique to define and quantify the trochlea volume and length using an axial computed tomography. This technique was applied to a series of patients surgically treated for recurrent patellofemoral instability and the measurements compared to a control group. Methods: From 2007 to 2013, 99 control patients (136 knees) were identified from trauma CT scans obtained during admission at our Level I trauma hospital. Patients older than 35y/o or with fractures in the distal femur were excluded. Axial cuts at 1.25 mm were used to measure trochlea volume; defined to be from the physeal scar to the final axial image in which the sulcus could be visualized (Figure 1). Trochlear groove distance was measured from a midline sagittal reformatted image perpendicular to the posterior margin of the femoral condyles. The inter-observer reliability was assessed with independent measurements from attending orthopedist, MSK radiologist and two senior residents. Dysplasia patient cohort was a series of 35 patients (70knees) who were surgically treated for recurrent instability, by AAS or CME, from 2007-2013 and a diagnosis of dysplasia based on lateral knee radiograph. CT tracking studies are obtained from bilateral knees as a normal part of our pre-operative assessment. Institutional IRB approval was obtained for data retrieval. Results: Control cohort average age 25 +/- 4 years, 68 M:31F, without documented history of patella instability on chart review. Dysplastic cohort average age 24 +/- 5 years, 2 M:33F, all 35 patients had bilateral knees scanned. Statistically significant differences were noted in comparing the trochlea volume (3.75 +/- 0.97 cm3 vs. 2.0+/- 0.56 cm3) and the trochlea length (34.8 +/- 4.9 mm vs. 31.7 +/- 4.2 mm) between control and dysplastic cohorts respectively. Comparing female only patients demonstrated difference in trochlea volume (2.89 +/- 0.57 cm3 vs. 2.0+/- 0.36 cm3), but not trochlea length (31.7 +/- 2.5 mm vs. 31.7 +/- 2.7 mm). No difference in trochlea volume or length b/w symptomatic knee to asymptomatic contralateral knees in patients with recurrent instability (2.31 cm3 vs. 2.24 cm3) and (30.0 mm vs. 30.5 mm). Inter-observer reliability was assess measuring trochlea volume: ICC for Right Trochlea: 0.98, ICC Left Trochlea: 0.97. Conclusion: This novel technique clearly defines and quantifies the trochlea morphology into volume and length values with high ICC values. Applying this technique demonstrates a significant difference in both trochlea volume and length between a control group and patients treated for recurrent patellofemoral instability
Prospective Comparison of Auto and Allograft Hamstring Tendon Constructs for ACL Reconstruction
Although allograft use for primary anterior cruciate ligament reconstruction has continued to increase during the last 10 years, concerns remain regarding the long-term function of allografts (primarily that they may stretch with time) and clinical efficacy compared with autograft tendons. We attempted to address these issues by prospectively comparing identical quadrupled hamstring autografts with allograft constructs for primary anterior cruciate ligament reconstruction in patients with a minimum followup of 3 years. Eighty-four patients (37 with autografts and 47 with allografts) were enrolled; the mean followup was 52 ± 11 months for the autograft group and 48 ± 8 months for the allograft group. Outcome measurements included objective and subjective International Knee Documentation Committee scores, Lysholm scores, Tegner activity scales, and KT-1000 arthrometer measurements. The two cohorts were similar in average age, acute or chronic nature of the anterior cruciate ligament rupture, and incidence of concomitant meniscal surgeries. At final followup, we found no difference in terms of Tegner, Lysholm, KT-1000, or International Knee Documentation Committee scores. Five anterior cruciate ligament reconstructions failed: three in the autograft group and two in the allograft group. Our data suggest laxity is not increased in allograft tendons compared with autografts and clinical outcome scores 3 to 6 years after surgery are similar