The cyclic distribution of various types of carbonates and Mg-clays in early Cretaceous rift-sag phase lacustrine carbonates from the subsurface of the South Atlantic provides an insight into how evolving lake chemistries in highly alkaline settings control facies development. The typically subdecametre scale symmetrical and asymmetrical cyclothems exhibit three main components: mud-grade laminated carbonates, millimetre-diameter spherulites with evidence of having been in a matrix of Mg-silicates, and millimetre–centimetre calcitic shrub-like growths. The laminites contain conspicuous numbers of ostracods and vertebrate remains and were produced by short-lived pluvial events, causing expansion of shallow lakes. Later evaporation triggered Mg-silicate precipitation and calcite nucleation within gels to produce spherulitic textures. When the rate of gel precipitation decreased or ceased, calcite growth, now less inhibited, produced shrub-like calcites resembling those produced abiotically in modern travertines, although still with some evidence of the former presence of some Mg-silicates. Physical reworking of these sediments led to the dispersion of the gels and the concentration of detrital carbonate components. Despite earlier proposals, evidence of microbial processes producing carbonates in these Cretaceous lake deposits is rare and the application of facies models based on modern and ancient microbialite analogues maybe be misplaced.

Trochlear dysplasia is an important anatomical abnormality in symptomatic patellar instability. Our study assessed the mismatch between the bony and cartilaginous morphology in patients with a dysplastic trochlea compared with a control group. MRI scans of 25 knees in 23 patients with trochlear dysplasia and in 11 patients in a randomly selected control group were reviewed retrospectively in order to assess the morphology of the cartilaginous and bony trochlea. Inter- and intra-observer error was assessed. In the dysplastic group there were 15 women and eight men with a mean age of 20.4 years (14 to 30). The mean bony sulcus angle was 167.9 degrees (141 degrees to 203 degrees), whereas the mean cartilaginous sulcus angle was 186.5 degrees (152 degrees to 214 degrees; p < 0.001). In 74 of 75 axial images (98.7%) the cartilaginous contour was different from the osseous contour on subjective assessment, the cartilage exacerbated the abnormality. Our study shows that the morphology of the cartilaginous trochlea differs markedly from that of the underlying bony trochlea in patients with trochlear dysplasia. MRI is necessary in order to demonstrate the pathology and to facilitate surgical planning.

Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine.

We report a prospective analysis of clinical outcome in patients treated with medial patellofemoral ligament (MPFL) reconstruction using an autologous semitendinosus graft. The technique includes superolateral portal arthroscopic assessment before and after graft placement to ensure correct graft tension and patellar tracking before fixation. Between October 2005 and October 2010, a total of 201 consecutive patients underwent 219 procedures. Follow-up is presented for 211 procedures in 193 patients with a mean age of 26 years (16 to 49), and mean follow-up of 16 months (6 to 42). Indications were atraumatic recurrent patellar dislocation in 141 patients, traumatic recurrent dislocation in 50, pain with subluxation in 14 and a single dislocation with persistent instability in six. There have been no recurrent dislocations/subluxations. There was a statistically significant improvement between available pre- and post-operative outcome scores for 193 patients (all p < 0.001). Female patients with a history of atraumatic recurrent dislocation and all patients with history of previous surgery had a significantly worse outcome (all p < 0.05). The indication for surgery, degree of dysplasia, associated patella alta, time from primary dislocation to surgery and evidence of associated cartilage damage at operation did not result in any significant difference in outcome. This series adds considerably to existing evidence that MPFL reconstruction is an effective surgical procedure for selected patients with patellofemoral instability.

A number of measurements of patellar height are in clinical use all of which reference from the tibia. The patellotrochlear index (PTI) has been proposed recently as a more accurate reflection of the functional height of the patella and described in normal knees. We compared patellar height measurements in patients with patellofemoral dysplasia. In a retrospective analysis of the MRI scans of 33 knees in 29 patients with patellofemoral dysplasia we assessed the inter- and intraobserver reliability of four patellar height measurements: the recently described PTI, Insall-Salvati (IS), Blackburne-Peel (BP) and Caton-Deschamps (CD) ratios. We also assessed the correlation between the different measurements in predicting patella alta. Three blinded observers on two separate occasions performed the measurements. There were 21 females and 8 males with a median age of 21 years (range 13-33). Statistical analysis revealed good inter-observer reliability for all measurements (0.78 for PTI, 0.78 for IS, 0.73 for BP and 0.77 for CD). Intra-observer reliability was also good (0.80, 0.83, 0.75 and 0.78, respectively). There was weak correlation between the PTI and the other ratios for patella alta. There was a strong correlation between the CD and BP ratios (0.96) and a moderate correlation between IS and CD and IS and BP ratios (0.594 and 0.539, respectively). We propose the PTI as a more clinically relevant measure than the IS, CD and BP ratios.