Cell-free cartilage repair in large defects of the knee: increased failure rate 5 years after implantation of a collagen type I scaffold.

INTRODUCTION: Cartilage defects of the knee remain a challenging problem in orthopedic surgery despite the ongoing improvements in regenerative procedures such as the autologous chondrocyte transplantation. Due to the lack of donor-site morbidity and the single-stage procedure cell-free scaffolds are an interesting alternative to cell-based procedures. But as currently mid- and long-term data are lacking, the aim of the present study was to present mid-term clinical, radiological and histological results of a cell-free collagen type I scaffolds for cartilage repair. MATERIALS AND METHODS: Twenty-eight patients were followed prospectively. Clinical evaluation using patient-reported outcome measures (KOOS, IKDC; VAS for pain, Tegner score for activity) as well as radiologic evaluation of the repair tissue (MOCART) was performed at 1 year, 2 years and 5 years. Histologic evaluation of the repair tissue was done in case of revision surgery using the ICRS II score for human cartilage repair. RESULTS: In these large cartilage defects with a mean defect size of 3.7 ± 1.9 cm2, clinical failure necessitating revision surgery was seen in 5 of 28 patients (18%). While the remaining patients showed good-to-excellent clinical results (KOOS, IKDC, VAS, Tegner), the radiologic appearance of the repair tissue showed a reduction of the MOCART score between the 2- and 5-year follow-up. Histologic evaluation of the repair tissue showed a cartilage-like appearance with no signs of inflammation or cell death but an overall medium tissue quality according to the ICRS II Score. CONCLUSION: The use of this cell-free collagen type I scaffold for large defects showed increased wear of the repair tissue and clinical failure in 18% of cases at 5-year follow-up.

Femoral tunnel widening is associated with tunnel malposition but not with clinical failure after medial patellofemoral ligament reconstruction with a free gracilis tendon graft.

INTRODUCTION: MPFL reconstruction is widely and successfully used for treating patella instability, either as a standalone procedure or in combination. Although different techniques allow for MPFL reconstruction, the use of a free tendon graft is one of the most commonly used. The phenomenon of tunnel widening or tunnel enlargement is well described in ACL reconstruction, but so far only little effort has been put into evaluating this phenomenon after MPFL reconstruction. MATERIALS AND METHODS: Patients who received an MPFL reconstruction with a free gracilis tendon graft were identified by review of patient files. Additional clinical examination and magnetic resonance imaging were performed to assess tunnel enlargement and clinical outcome. RESULTS: Fifty-one knees of 49 patients (34 female, 17 male) with a mean follow-up of 3.0 ± 1.4 years were included in this study. Mean age at the time of surgery was 22.6 ± 8.5 years. Mean Tegner score decreased from preoperative 5.3 ± 2.0 to 4.0 ± 1.4 postoperative. Postoperative IKDC and Kujala scores were 74 ± 16 and 80 ± 15, respectively. Twenty-three patients showed a tunnel enlargement at follow-up examination. Of these 23 patients, 20 showed a tunnel that was positioned too proximal, whereas only 13 of the 28 patients showing no enlargement had a tunnel that was positioned too proximal (p = 0.0033). Interestingly, patients showing a tunnel enlargement at follow-up examination also showed significantly better Kujala (84 ± 12 vs. 75 ± 16; p = 0.03) and IKDC scores (80 ± 7 vs. 70 ± 19; p = 0.02) when compared to the non-enlarged group. CONCLUSION: Tunnel enlargement after MPFL reconstruction with a free gracilis tendon graft seems to be connected to mechanical overload due to a proximal malposition of the femoral tunnel. Interestingly, this did not influence clinical outcome as patients with tunnel enlargement showed better Kujala and IKDC scores.

Diffusion weighted MRI of osteoid osteomas: Higher ADC values after radiofrequency ablation.

PURPOSE: Feasibility of diffusion weighted MRI (DWI) pre- and post-radiofrequency ablation (RFA) in patients with osteoid osteoma (OO). MATERIAL AND METHODS: Ten patients (1 female, 24±9years) received RFA of OO (mean size 8.7±3.2mm). Two OO recurred, in one of these a second RFA was performed. A 1.5T DWI (b=50, 400, and 800s/mm(2)) and a fat saturated DCE MRI were obtained the day before and after RFA. In DWI, the mean apparent diffusion coefficient (ADC) was recorded. With DCE MRI, signal-to-noise ratio, contrast-to-noise ratio, absolute signal intensity (SI), relative SI, and SI ratio were documented. All parameters were compared pre- and post-RFA using paired Wilcoxon rank test. RESULTS: ADC values were significantly higher post-ablation, 1.6±0.5µm(2)/ms versus 1.3±0.6µm(2)/ms (p<0.05). Perfusion was significantly reduced after ablation [SNR, CNR, SI, %SI, and SI OO/SI muscle]; post-RFA: 55±13, 27±20, 757±534, 102±16, and 1.6±0.2; pre-RFA: 88±37, 65±22, 1038±755, 226±51, and 2.0±0.5 (p<0.05). DISCUSSION: DWI is feasible in OO. ADC values increased and contrast enhancement decreased after RFA of OO. This may be explained by RFA-induced necrosis and devascularization.

Refinement of screening for familial pancreatic cancer.

OBJECTIVE: Surveillance programmes are recommended for individuals at risk (IAR) of familial pancreatic cancer (FPC) to detect early pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC). However, the age to begin screening and the optimal screening protocol remain to be determined. METHODS: IAR from non-CDKN2A FPC families underwent annual screening by MRI with endoscopic ultrasonography (EUS) in board-approved prospective screening programmes at three tertiary referral centres. The diagnostic yield according to age and different screening protocols was analysed. RESULTS: 253 IAR with a median age of 48 (25-81) years underwent screening with a median of 3 (1-11) screening visits during a median follow-up of 28 (1-152) months. 134 (53%) IAR revealed pancreatic lesions on imaging, mostly cystic (94%), on baseline or follow-up screening. Lesions were significantly more often identified in IAR above the age of 45 years (p<0.0001). In 21 IAR who underwent surgery, no significant lesions (PDAC, pancreatic intraepithelial neoplasia (PanIN) 3 lesions, high-grade intraductal papillary mucinous neoplasia (IPMN)) were detected before the age of 50 years. Potentially relevant lesions (multifocal PanIN2 lesions, low/moderate-grade branch-duct IPMNs) occurred also significantly more often after the age of 50 years (13 vs 2, p<0.0004). The diagnostic yield of potentially relevant lesions was not different between screening protocols using annual MRI with EUS (n=98) or annual MRI with EUS every 3rd year (n=198) and between IAR screened at intervals of 12 months (n=180) or IAR that decided to be screened at ≥24 months intervals (n=30). CONCLUSIONS: It appears safe to start screening for PDAC in IAR of non-CDKN2a FPC families at the age of 50 years. MRI-based screening supplemented by EUS at baseline and every 3rd year or when changes in MRI occur appears to be efficient.

[Atlas fracture due to aneurysmal bone cyst after minor trauma]. / Fraktur des Atlas durch eine aneurysmatische Knochenzyste nach Bagatelltrauma.

Aneurysmal bone cysts predominantly occur in young adults and the long bones, the lumbar spine and the pelvis are mainly affected. This article presents the case of a 22-year-old woman with the very rare localization of an aneurysmal bone cyst of the atlas and an atlas fracture after a minor trauma. The initial radiological diagnosis was a suspicted aneurysmal bone cyst which was confirmed histologically. Due to the unstable fracture it was decided to carry out surgical treatment with occipitocervical stabilization in combination with a transoral bone graft. After a period of 11 months the fracture had completely healed and the implants were removed without any complications.

Prevention of type II endoleak using the AMPLATZER vascular plug before endovascular aneurysm repair.

OBJECTIVE: We evaluated the feasibility of visceral artery and lumbar artery (LA) embolization using AMPLATZER vascular plug (AVP) types 4 and 2 (AVP4, AVP2) prior to endovascular aneurysm repair (EVAR) to prevent the development of a type II endoleak. METHODS: Between January 2008 and April 2010, 45 arteries in 33 male patients were embolized with 44 AVP4 and one AVP2. Artery name and diameter; device number and size; and intervention, fluoroscopy, and deployment times for each procedure and each device were recorded. Computed tomography (CT) angiography was performed 2 days and 3, 6, 12, 18, 24, and 36 months after EVAR to confirm successful EVAR and embolotherapy, exclude endoleaks, and evaluate aneurysm shrinkage. RESULTS: AVP4 devices were implanted into the inferior mesenteric arteries in 33 cases, lumbar arteries in seven cases, and pelvic and renal arteries in two cases each. An AVP2 device was inserted into the gluteal artery in one case. The success rate was 100%, with total occlusion of all target vessels. No endoleaks were found in follow-up CT angiography. CONCLUSION: The use of AVP prior to EVAR is an efficient embolization technique that prevents the development of type II endoleaks.

Primary stability of tibial components in TKA: in vitro comparison of two cementing techniques.

In spite of improvements in cementing technique, migration of tibial component remains a problem in total knee arthroplasty. This study compares the primary stability of tibial components using two different cementing techniques with roentgen stereophotogrammetric analysis (RSA) in vitro. A total of 20 tibia specimens were matched into two groups, 10 specimens per group. Cementing technique was randomized to each group. In the first group only the base and in the second group the base and stem were cemented. The implants and the tibial metaphysis were marked with markers for the RSA analysis. All specimens were tested with an axial load of 2,000 N for 1,000 and 10,000 cycles and RSA analysis was performed. Endpoints for radiosterometric analysis were maximum total point motion, maximum subsidence, lift off, rotation and translation along the x-, y-, and z-axes. After 1,000 and 10,000 cycles, no significant differences could be found, but two tibial components of the surface cementing group showed a migration of more than 2 mm defined as failure compared to six failed tibial components in the full cementing group (P = 0.068). This higher number of failed arthroplasties in the fully cemented prosthesis group demonstrates a disadvantageous load distribution in the tibia apophysis which can cause an early component loosening.

B-type natriuretic peptide and wall stress in dilated human heart.

Background Although B-type natriuretic peptide (BNP) is used as complimentary diagnostic tool in patients with unknown thoracic disorders, many other factors appear to trigger its release. In particular, it remains unresolved to what extent cellular stretch or wall stress of the whole heart contributes to enhanced serum BNP concentration. Wall stress cannot be determined directly, but has to be calculated from wall volume, cavity volume and intraventricular pressure of the heart. The hypothesis was, therefore, addressed that wall stress as determined by cardiac magnetic resonance imaging (CMR) is the major determinant of serum BNP in patients with a varying degree of left ventricular dilatation or dysfunction (LVD). Methods A thick-walled sphere model based on volumetric analysis of the LV using CMR was compared with an echocardiography-based approach to calculate LV wall stress in 39 patients with LVD and 21 controls. Serum BNP was used as in vivo marker of a putatively raised wall stress. Nomograms of isostress lines were established to assess the extent of load reduction that is necessary to restore normal wall stress and related biochemical events. Results Both enddiastolic and endsystolic LV wall stress were correlated with the enddiastolic LV volume (r = 0.54, P < 0.001; r = 0.81, P < 0.001). LV enddiastolic wall stress was related to pulmonary pressure (capillary: r = 0.69, P < 0.001; artery: r = 0.67, P < 0.001). Although LV growth was correlated with the enddiastolic and endsystolic volume (r = 0.73, P < 0.001; r = 0.70, P < 0.001), patients with LVD exhibited increased LV wall stress indicating an inadequately enhanced LV growth. Both enddiastolic (P < 0.05) and endsystolic (P < 0.01) wall stress were increased in patients with increased BNP. In turn, BNP concentration was elevated in individuals with increased enddiastolic wall stress (>8 kPa: 587 +/- 648 pg/ml, P < 0.05; >12 kPa: 715 +/- 661 pg/ml, P < 0.001; normal < or =4 kPa: 124 +/- 203 pg/ml). Analysis of variance revealed LV enddiastolic wall stress as the only independent hemodynamic parameter influencing BNP (P < 0.01). Using nomograms with "isostress" curves, the extent of load reduction required for restoring normal LV wall stress was assessed. Compared with the CMR-based volumetric analysis for wall stress calculation, the echocardiography based approach underestimated LV wall stress particularly of dilated hearts. Conclusions In patients with LVD, serum BNP was increased over the whole range of stress values which were the only hemodynamic predictors. Cellular stretch appears to be a major trigger for BNP release. Biochemical mechanisms need to be explored which appear to operate over this wide range of wall stress values. It is concluded that the diagnostic use of BNP should primarily be directed to assess ventricular wall stress rather than the extent of functional ventricular impairment in LVD.