Defining modes of failure after joint-preserving surgery of the hip.

AIMS: Joint-preserving surgery of the hip (JPSH) has evolved considerably and now includes a number of procedures, including arthroscopy, surgical dislocation, and redirectional osteotomies of the femur and acetabulum. There are a number of different factors which lead to failure of JPSH. Consequently, it is of interest to assess the various modes of failure in order to continue to identify best practice and the indications for these procedures. PATIENTS AND METHODS: Using a retrospective observational study design, we reviewed 1013 patients who had undergone JPSH by a single surgeon between 2005 and 2015. There were 509 men and 504 women with a mean age of 39 years (16 to 78). Of the 1013 operations, 783 were arthroscopies, 122 surgical dislocations, and 108 peri-acetabular osteotomies (PAO). We analysed the overall failure rates and modes of failure. Re-operations were categorised into four groups: Mode 1 was arthritis progression or organ failure leading to total hip arthroplasty (THA); Mode 2 was an Incorrect diagnosis/procedure; Mode 3 resulted from malcorrection of femur (type A), acetabulum (type B), or labrum (type C) and Mode 4 resulted from an unintended consequence of the initial surgical intervention. RESULTS: At a mean follow-up of 2.5 years, there had been 104 re-operations (10.2%) with a mean patient age of 35.5 years (17 to 64). There were 64 Mode 1 failures (6.3%) at a mean of 3.2 years following JPSH with a mean patient age of 46.8 years (18 to 64). There were 17 Mode 2 failures (1.7%) at a mean of 2.2 years post-JPSH with a mean patient age of 28.9 years (17 to 42) (2% scopes; 1% surgical dislocations). There were 19 Mode 3 failures (1.9%) at a mean of 2.0 years post-JPSH, with a mean patient age of 29.9 years (18 to 51) (2% scopes; 2% surgical dislocations; 5% PAO). There were 4 Mode 4 failures (0.4%) at a mean of 1.8 years post-JPSH with a mean patient age of 31.5 years (15 to 43). Using the modified Dindo-Clavien classification system, the overall complication rate among JPSHs was 4.2%. CONCLUSION: While defining the overall re-operation and complication rates, it is important to define the safety and effectiveness of JPSH. Standardisation of the modes of failure may help identify the best practice. Application of these modes to large clinical series, such as registries, will assist in further establishing how to improve the efficacy of JPSH. Cite this article: Bone Joint J 2017;99-B:303-9.

A novel method for determining calibration and behavior of PVDF ultrasonic hydrophone probes in the frequency range up to 100 MHz.

A new calibration technique for PVDF ultrasonic hydrophone probes is described. Current implementation of the technique allows determination of hydrophone frequency response between 2 and 100 MHz and is based on the comparison of theoretically predicted and experimentally determined pressure-time waveforms produced by a focused, circular source. The simulation model was derived from the time domain algorithm that solves the non linear KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation describing acoustic wave propagation. The calibration technique data were experimentally verified using independent calibration procedures in the frequency range from 2 to 40 MHz using a combined time delay spectrometry and reciprocity approach or calibration data provided by the National Physical Laboratory (NPL), UK. The results of verification indicated good agreement between the results obtained using KZK and the above-mentioned independent calibration techniques from 2 to 40 MHz, with the maximum discrepancy of 18% at 30 MHz. The frequency responses obtained using different hydrophone designs, including several membrane and needle probes, are presented, and it is shown that the technique developed provides a desirable tool for independent verification of primary calibration techniques such as those based on optical interferometry. Fundamental limitations of the presented calibration method are also examined.

On the application of ultrasonic contrast agents for blood flowmetry and assessment of cardiac perfusion.

The stability, size, and ultrasonic properties of several ultrasonic microbubble contrast agents such as Albunex, SHU-454, 1% hydrogen peroxide, and sonicated solutions such as 70% and 50% dextrose, 70% sorbitol, 5% albumin, Renografin-76, and others were evaluated. Albunex was the only tested agent that was sufficiently stable over an extended period of time for in vitro ultrasonic characterization. The attenuation and backscatter coefficients of Albunex at 5 and 7.5 MHz were found to be linearly proportional to microsphere concentration at low concentrations (less than 0.01% for attenuation and less than 0.002% for backscatter). Also, Albunex was found to be more echogenic than soft tissues at 5 MHz even after being diluted to 0.0003% of the original concentration. Next, the feasibility of using this acoustic information for contrast blood flowmetry was investigated. In vitro flow estimates in a mock flow loop were made using only the ultrasonic properties of the contrast agent. Bolus injections of Albunex and indicator-dilution curves inferred from ultrasonic measurements were used to estimate calibrated flow rate ranging from 400 to 5000 mL/min. The flow estimates from attenuation measurements showed a good correlation with those from an independent method (r = 0.97), but the results from backscatter studies did not correlate well. These results demonstrate that attenuation measurement may be a feasible alternative for in vivo blood flow measurement in conjunction with the indicator dilution principle or estimation of tissue perfusion such as myocardial perfusion using a time-activity approach.

[Differential diagnostic assessment of IV glucose tolerance in affective disorders (author's transl)]. / Zur differentialdiagnostischen Bewertung der i.v.-Glucose-Toleranz in affektiven Erkrankungen.

Glucose intolerance should be regarded as an unspecific, though obligatory phenomenon in endogenous-involutional phases and as an unspecific adaptive finding in somatically based depression. Therefore, it is without differential diagnostic meaning in classifying depressive disorders. On the other hand, normal values of glucose tolerance found in depressive syndromes clinically diagnosed as endogenous-involutional represent a likelihood of underlying organicity.

[Pathological lability of venous fasting blood sugar regulation in psychotic disease]. / Pathologische Labilität venöser Nüchternblutzucker-Regulation in psychotischen Erkrankungen.

The lability of peripheral venous postabsorptive blood sugar regulation was investigated in 98 patients suffering from floridly psychotic diseases (45 somatically based psychoses, 27 endogenous/involutional depressions, and 26 schizophrenic psychoses). In total, 259 times, in 30-sec intervals, 10 fasting blood sugar values each were determined (so-called 'Anderson curves'). The maximal normal range of 36 mg% of spontaneous blood sugar oscillations in normal probands was exceeded in 17% of depressive, in 15% of schizophrenic, and in 12% of somatically based psychoses. The frequency and probability of appearance of pathological Anderson curves proved independently of any clinical-psychiatric diagnosis, and only significantly correlated with the criterion 'psychotically ill'. Discussed are primary central deviations from nominal gluco-sensitive regulatory 'tone' as postulated cause of pathological lability of venous blood sugar homeostasis resulting. Besides additional, pre-known glucose-metabolic derangements accompanying certain neuropsychiatric syndromes, pathological Anderson curves in psychotic illness are looked at as unspecific functional deviations involving bipolar-adrenergic dysbalances.

Gilles de la Tourette's syndrome with direct evidence of organicity.

A severe manifestation of Gilles de la Tourette's syndrome (GTS) which developed about six months subsequent to angiographic complications is reported. Acute, post-angiographically derived neuropsychiatric symptoms which continually bridged the interval between central damage suffered, and the final onset of GTS strongly favored the case for underlying organicity. This case probably represents the first direct report of preceding brain lesion triggering off GTS and negates previous trends to attribute psychogenic causes to GTS. As to pathophysiologic mechanisms possibly governing hyperkinesias common in GTS, the neuronal functional rules of denervation and denervation supersensitivity are applied to striatal dopamine-facilitated nerve cell populations.