New tip-apex distance and calcar-referenced tip-apex distance cut-offs may be the best predictors for cut-out risk after intramedullary fixation of proximal femur fractures

Cut-out is one of the most common mechanical failures in the internal fixation of trochanteric hip fractures. The tip-apex distance (TAD), and the calcar-referenced tip apex distance (CalTAD) are the radiographic parameters that most predict the risk of cut-out. The optimal CalTAD value has not yet been defined, but the optimal TAD value is reported as 25 mm or less. However, this cut-off is highly specific but poorly sensitive. The aim of this study was to determine highly specific and sensitive TAD and CalTAD values and shed light on the role of other clinical variables. A total of 604 patients were included in this retrospective cross-sectional study. For each patient the following data were recorded: number of cut-out, AO/OTA classification, quality of the reduction, type of nail, cervicodiaphyseal angle, type of distal locking, post-operative weight-bearing, TAD and CalTAD values, and the position of the screw head in the femoral head according to the Cleveland system. The incidence of cut-out across the sample was 3.1%. The median TAD in the cut-out group was 38.72, while in the no cut-out group it was 22.16. The median CalTAD in the cut-out group was 39.34, while in the no cut-out group it was 22.19. The cut-off values for TAD and CalTAD with highest value of sensitivity and specificity for the risk of cut-out were 34.8 and 35.2, respectively. The incidence of cut-out can be reduced by performing careful minimal reduction and ensuring stable fixation by avoiding TAD > 34.8 mm and CalTAD > 35.2 mm.

Bilateral dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation in an alpaca

CASE DESCRIPTION A 14-month-old female alpaca presented with a 3-week history of acute left hind limb lameness and swelling of the left tarsal region. CLINICAL FINDINGS Radiography revealed intermittent dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation. TREATMENT AND OUTCOME In an attempt to stabilize the talus, screws were placed in the distomedial aspect of the talus and the plantaromedial aspect of the central tarsal bone, and a stainless-steel wire was placed around the screws in a figure-eight pattern. The screw head of the proximal screw broke within 4 weeks after surgery, but subluxation did not recur, and the lameness resolved. Seven months later, the same condition was diagnosed in the opposite hind limb and was treated similarly. Implants remained intact on this side, but the animal started to show signs of pain and inability to flex the tarsal joint, prompting removal of the distal screw. Subsequently, the animal became sound and produced 2 healthy crias, but was euthanatized 4 years after the second surgery because of coccidiosis. CLINICAL RELEVANCE Dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation is a sporadic condition in New World camelids. This report provides the first account of successful treatment by surgical stabilization of the medial aspect of the proximal intertarsal joint.

The contribution of statistical processes in the control of technological processes

In this paper, a manufacturing process is analyzed, having as quality characteristic the “height of the screw head”, using analyzes and representative diagrams. Based on this case study, the way to solve these types of problems using the Quality Control Chart module of the WinQSB program, as well as the XLSTAT program is presented.

Selected aspects of proximal femoral epiphysis fixation in children with early stages of slipped capital femoral epiphysis

BACKGROUND: Epiphyseodesis of the femoral head in the early stages of slipped capital femoral epiphysis using auto-, allografts, and synthetic implant may result in deformities of the femur leading cam-type femoroacetabular impingement and dysfunction of the gluteal muscles. Most surgeons refused this intervention and favor in situ fixation of the epiphysis with modern metal instrumentation and, in particular, cannulated screws with proximal threading. However, the number of screws that provide stable fixation and how to reduce their negative effect on the enchondral growth of the femur remain controversial. AIM: To improve the results of surgical treatment in children with early stages of slipped capital femoral epiphysis. MATERIALS AND METHODS: The radiological results of surgical treatment of 40 patients (80 affected joints) aged from 11 to 14 years with slipped capital femoral epiphysis of stage 1 in one joint and stage 2 in the other joint were analyzed. 20 children were divided into two groups. In each group, the epiphysis was fixed with a 7.0 mm cannulated screw. In the first group, the screw head was held on the cortical layer. In the second group, the screw head was held 510 millimeters away from the cortical layer. Long-term results were evaluated at the age of 1718 years when no signs of enchondral and ecchondral growth of the proximal femur were noted. The obtained data were subjected to statistical analysis. RESULTS: The fixation of the epiphysis was stable in all 80 joints. The shape of epimetaphysis in the joints of stage 2 did not change in most patients by the end of femoral growth. However, the correction recorded in 32.5% of cases was more often observed in children of the second group. The shape of epimetaphysis in all 40 joints with stage 1 of the disease remained normal. The mean length of the epimetaphysis was greater in the second group than in the first group by the end of growth regardless of the stage of the pathologic process during surgery. CONCLUSIONS: The considered method of proximal femoral epiphysis fixation, which excludes the compressive effect of a cannulated screw with proximal threading on the epiphyseal growth cartilage, provides reliable epiphysis retention in the early stages of slipped capital femoral epiphysis. It has a less negative effect on the enchondral growth of the femoral component of the joint.

Accuracy of Guided Surgery and Real-Time Navigation in Temporomandibular Joint Replacement Surgery

Background: Sophisticated guided surgery has not been implemented into total joint replacement-surgery (TJR) of the temporomandibular joint (TMJ) so far. Design and in-house manufacturing of a new advanced drilling guide with vector and length control for a typical TJR fossa component are described in this in vitro study, and its accuracy/utilization was evaluated and compared with those of intraoperative real-time navigation and already available standard drilling guides. Methods: Skull base segmentations of five CT-datasets from different patients were used to design drilling guides with vector and length control according to virtual surgical planning (VSP) for the TJR of the TMJ. Stereolithographic models of the skull bases were printed three times for each case. Three groups were formed to compare our newly designed advanced drilling guide with a standard drilling guide and drill-tracking by real-time navigation. The deviation of screw head position, screw length and vector in the lateral skull base have been evaluated (n = 72). Results: There was no difference in the screw head position between all three groups. The deviation of vector and length was significantly lower with the use of the advanced drilling guide compared with standard guide and navigation. However, no benefit in terms of accuracy on the lateral skull base by the use of real-time navigation could be observed. Conclusion: Since guided surgery is standard in implant dentistry and other CMF reconstructions, this new approach can be introduced into clinical practice soon, in order to increase accuracy and patient safety.

Anatomic and Radiographic Safe Zone for Posterior Malleolar Screw Placement

Background: The most appropriate treatment and management of posterior malleolar fractures (PMFs) lacks consensus. Indirect reduction and fixation with posterior to anterior (PA) screw shows promise by avoiding the risks associated with direct reduction or indirect anterior to posterior approaches. Some authors have raised concerns about potential risk to nearby structures with the PA technique, including hardware prominence into the syndesmosis. This study highlights use of the posteromedial vertical syndesmotic line (PVSL) as a fluoroscopic landmark, helping surgeons avoid intrasyndesmotic placement. Study aims are to evaluate PVSL correspondence with posterior border of the incisura tibialis and to define a safe zone between this line and flexor hallucis longus tendon. Methods: Indirect PA screw placement was completed on 10 cadaveric specimens, followed by fluoroscopy in mortise and lateral views. Dissection was performed to assess screw placement relative to the posteromedial border of the syndesmosis. The posterior border of the syndesmosis was marked with a radiopaque wire. Repeat imaging was completed to validate the fluoroscopic PVSL is representative of the posteromedial border of the tibial incisura. Results: On dissection, 9 out of 10 cadavers had accurate screw placement with no penetration into the syndesmosis. Corresponding imaging showed the screw head to be medial to the marker on mortise view. For the specimen with penetration into the syndesmosis, imaging confirmed that the screw head was lateral to the marker on mortise views. The radiopaque marker correlated with the PVSL for all specimens when comparing anatomic to radiographic findings. A radiographic safe zone is defined for the PA screw 12 mm medial to the PVSL to ensure no iatrogenic injury to the flexor hallucis longus tendon. Conclusion: This study demonstrated that a posterior incisura tibialis fluoroscopic landmark is unambiguous in localizing the posterior syndesmotic border and that screws medial to this line are safely out of the syndesmosis, while screws placed lateral are either in or at risk of intrasyndesmotic placement. A safe zone is defined for screw placement. Clinical Relevance: This article describes a radiographic and clinical safe zone for fixation and hardware placement during open reduction internal fixation (ORIF) of PMFs. This information will assist surgeons in avoiding intrasyndesmotic hardware placement as well as injury to deep soft tissue structures.

NUMERICAL COMPARISON OF TRANSGINGIVAL AND SUBGINGIVAL DENTAL IMPLANTS IN REGARD TO THEIR STRESS DISTRIBUTIONS

Most modern dental implants differentiate in regard to the fixation of the abutment into two main categories - the external or internal hexagon or octagon. We performed mechanical tests according to the ČSN EN ISO 14801 standard on a dental implant variant using the external hex. We found that failure of all implant specimens occured below the screw head. To improve the current geometry, we performed numerical analysis of an alternative variant (internal hex) and compared it with analysis of the current geometry (external hex). It was found that the stress distribution of the variant with internal hex is preferable to the old variant. Although extreme values of shear stress in the corresponding plane of loading are higher, they do not concentrate below the screw head, where the screw itself is thinner and more prone to breaking. Therefore, it seems that the new variant of the dental implant is stronger, which is still to be proven by mechanical tests.

Which TAD and CALTAD Cut-Offs Best Predict Cut-Out Risk for Intramedullary Fixation of Proximal Femur Fractures?

Purpose: Cut-out is one of the most common mechanical failures in the internal fixation of trochanteric hip fractures. The tip-apex distance (TAD), and the calcar-referenced tip apex distance (CalTAD) are the radiographic parameters that most predict the risk of cut-out. The optimal CalTAD value has not yet been defined, but the optimal TAD value is reported as 25 mm or less. However, this cut-off is highly specific but poorly sensitive. The aim of this study was to determine highly specific and sensitive TAD and CalTAD values and shed light on the role of other clinical variables.Methods: A total of 604 patients were included in this retrospective cross-sectional study. For each patient the following data were recorded: number of cut-out, AO/OTA classification, quality of the reduction, type of nail, cervicodiaphyseal angle, type of distal locking, post-operative weight-bearing, TAD and CalTAD values, and the position of the screw head in the femoral head according to the Cleveland system.Results: The incidence of cut-out across the sample was 3.1%. The median TAD in the cut-out group was 38.72, while in the no cut-out group it was 22.16. The median CalTAD in the cut-out group was 39.34, while in the no cut-out group it was 22.19. The cut-off values for TAD and CalTAD with highest value of sensitivity and specificity for the risk of cut-out were 34.8 and 35.2, respectively. Conclusions: The incidence of cut-out can be reduced by performing careful minimal reduction and ensuring stable fixation by avoiding TAD>34.8mm and CalTAD>35.2 mm.