Long - term survivorship and clinical results of the navigated withdrawn ASR ™.

INTRODUCTION: Primary goals of the study were to present the mid - to long - term survivorship and clinical, radiological and metal serological results of the first stem - navigated ASR™ resurfacing at our clinic. Secondary goals were to determine the influence of stem - navigation on the outcome and risk factors for revision in our cohort. METHODS: From Mai 2006 to Mai 2009 46 ASR™ resurfacing hip systems have been implanted in 43 patients with a median age of 55 years. At final follow - up (33 patients with a mean follow -up of 89,6 months) guidelines were followed and HHS and HOOS were completed. Inclination, NSA and SSA were measured on radiographs and signs of loosening were graded. Risk factors for revision were compared in the non - revision and revision group. RESULTS: Mean cumulative survival of the prosthesis after 99,9 Months was 81,8%. At final follow - up 8 revisions were performed. Median HHS was 97, HOOS was 87,2. Four prostheses showed signs of loosening and nine heterotopic ossifications. All shaft components, except one, were placed in minimal valgus position to avoid risk for fracture. Age and diameter of the femoral component were significantly different between the non - revision and revision group. DISCUSSION: Survivorship is comparable to numbers found in other studies. Patients with complete final follow - up in general had good objective and subjective scores and few signs of loosening in the radiological follow - up. Navigation might have a positive effect on reduction of risk for fracture. Age and diameter of the femoral component seem to influence the outcome.

Zonal T2* and T1Gd assessment of knee joint cartilage in various histological grades of cartilage degeneration: an observational in vitro study.

OBJECTIVES: Accurate assessment of cartilage status is increasingly becoming important to clinicians for offering joint preservation surgeries versus joint replacements. The goal of this study was to evaluate the validity of three-dimensional (3D), gradient-echo (GRE)-based T2* and T1Gd mapping for the assessment of various histological severities of degeneration in knee joint cartilage with potential implications for clinical management. METHODS: MRI and histological assessment were conducted in 36 ex vivo lateral femoral condyle specimens. The MRI protocol included a 3D GRE multiecho data image combination sequence in order to assess the T2* decay, a 3D double-echo steady-state sequence for assessment of cartilage morphology, and a dual flip angle 3D GRE sequence with volumetric interpolated breathhold examination for the T1Gd assessment. The histological sample analysis was performed according to the Mankin system. The data were then analysed statistically and correlated. RESULTS: We observed a significant decrease in the T2* and T1Gd values with increasing grades of cartilage degeneration (p<0.001) and a moderate correlation between T2* (r=0.514)/T1Gd (r=0.556) and the histological grading of cartilage degeneration (p<0.001). In addition, we noted a zonal variation in the T2* and T1Gd values reflecting characteristic zonal differences in the biochemical composition of hyaline cartilage. CONCLUSIONS: This study outlines the potential of GRE-based T2* and T1Gd mapping to identify various grades of cartilage damage. Early changes in specific zones may assist clinicians in identifying methods of early intervention involving the targeted joint preservation approach versus moving forward with unicompartmental, bicompartmental or tricompartmental joint replacement procedures. TRIAL REGISTRATION NUMBER: DRKS00000729.

Is the effect of a posterior cruciate ligament resection in total knee arthroplasty predictable?

PURPOSE: It is broadly supposed that in total knee arthroplasty, the flexion/extension gap ratio is increased after resection of the posterior cruciate ligament (PCL). However, studies are rare and results are inconsistent. Therefore, this study was conducted to determine whether PCL release regularly increases the flexion gap. METHODS: Data from 50 consecutive posterior stabilised knee prostheses were analysed retrospectively. Using imageless computer navigation, the joint-gap width was measured over the entire range of motion before and after PCL release. RESULTS: PCL release had no effect on the extension gap, but it increased the flexion gap significantly. An increase of >3 mm occurred in 36% of patients and of >5 mm in 12%. No clinically relevant effect (<2 mm) was found in 44% of patients. CONCLUSION: PCL release increased the flexion/extension gap ratio on average, but the individual effect could not be predicted. Therefore, we recommend PCL release before the femoral resections are performed, as this step mainly determines the ratio between extension and flexion gap.