Tibial tubercle osteotomy in patello-femoral instability and in patellar height abnormality

The aim of this study was to present the different surgical procedures of tibial tubercle osteotomies for patellar instability or patellar mispositioning such as patella alta or patella infera. This study analysed the Caton–Deschamps index used for assessment of vertical patella height in order to make a precise plan for tibial tuberosity osteotomies. This study included 61 knees (50 patients) treated for patellar instability with patella alta and 24 patients treated for patella infera of mechanical origin. The results of medial transfer of the tibial tuberosity, with or without distal transfer in cases of patellar instability with patella alta, gives excellent results for stability in 76.8% of the cases. The results of the proximal transfer of the tibial tuberosity in cases of patella infera were excellent or good in 80% of the cases in our series of 24 patients. A precise preoperative plan is needed with determination of the vertical patellar height using the Caton–Deschamps index and the situation of the tibial tuberosity and the Tibial Tubercle to Trochlear Groove distance (TT-TG) of the knee on CT scan in order to obtain satisfactory results

Equivalent wear performance of dual mobility bearing compared with standard bearing in total hip arthroplasty: in vitro study

PURPOSE: Osteolysis in total hip arthroplasty (THA) depends on polyethylene wear and dictates the survival of the prosthesis. Dual mobility in THAs, which is claimed to reduce dislocation risk, has very good long-term clinical results. However, little is known about how the liner wears in this design, compared to the standard single mobility model. METHODS: A comparative study looking at wear of a conventional ultra-high-molecular-weight polyethylene liner, using gravimetric measurement, between dual mobility implants and standard implants, was performed on a simulator in accordance with a normed protocol based on the same dimensions, environmental conditions and stresses. A linear regression test was employed. RESULTS: Under the same conditions (loading, cycles, sterilization, material and surface roughness), the gravimetric wear (for conventional polyethylene) is comparable between a standard and a dual mobility cup. This correlates to ten year follow-up results of dual mobility cup. DISCUSSION - CONCLUSION: This in vitro equivalent wear serves to confirm the very good long-term clinical results observed with dual mobility bearing, whose use should not be restricted by concerns about increased polyethylene wear

Risk of vascular injury when screw drilling for tibial tuberosity transfer

Purpose: During tibial tubercle transfer, popliteal vessels are at risk from drills and screws. The risk is around 0.11%, as described in the literature. We reviewed knee injected CT scan for analysis of the location of arteries, identified landmarks allowing minimizing risks, and defined a safe zone. Material and method: Distances between the posterior cortex and arteries were measured on CT scans from 30 adults (60 knees) at three levels (proximal part of the tibial tuberosity, 20 mm and 40 mm distally). Data were used to create a “risk map” with different angular sectors where the frequency of the presence of arteries was analyzed in each area. We also analyzed the position of 68 screws of 47 patients who underwent a medial tibial tuberosity transfer. Results: The nearest distance between artery and the posterior tibial cortex was found at the level corresponding to the top of the tuberosity with less than 1 mm, while the largest distance was found at the distal level. We were able to define a safe zone for drilling through the posterior tibial cortex which allows a safe fixation for the screws. This zone corresponds to the medial third of the posterior cortex. When the safe zone is not respected, screws that overtake the posterior cortex may be close to arteries as observed for 37 of the 68 screws analyzed. Conclusion: We described new landmarks and recommendations to avoid this complication during tibial tuberosity transfer.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Connexins: key mediators of endocrine function.

The appearance of multicellular organisms imposed the development of several mechanisms for cell-to-cell communication, whereby different types of cells coordinate their function. Some of these mechanisms depend on the intercellular diffusion of signal molecules in the extracellular spaces, whereas others require cell-to-cell contact. Among the latter mechanisms, those provided by the proteins of the connexin family are widespread in most tissues. Connexin signaling is achieved via direct exchanges of cytosolic molecules between adjacent cells at gap junctions, for cell-to-cell coupling, and possibly also involves the formation of membrane "hemi-channels," for the extracellular release of cytosolic signals, direct interactions between connexins and other cell proteins, and coordinated influence on the expression of multiple genes. Connexin signaling appears to be an obligatory attribute of all multicellular exocrine and endocrine glands. Specifically, the experimental evidence we review here points to a direct participation of the Cx36 isoform in the function of the insulin-producing β-cells of the endocrine pancreas, and of the Cx40 isoform in the function of the renin-producing juxtaglomerular epithelioid cells of the kidney cortex