Hybrid curvature-geometrical detection of landmarks for the automatic analysis of the reduction of supracondylar fractures of the femur.

BACKGROUND AND OBJECTIVE: The analysis of the features of certain tissues is required by many procedures of modern medicine, allowing the development of more efficient treatments. The recognition of landmarks allows the planning of orthopedic and trauma surgical procedures, such as the design of prostheses or the treatment of fractures. Formerly, their detection has been carried out by hand, making the workflow inaccurate and tedious. In this paper we propose an automatic algorithm for the detection of landmarks of human femurs and an analysis of the quality of the reduction of supracondylar fractures. METHODS: The detection of anatomical landmarks follows a knowledge-based approach, consisting of a hybrid strategy: curvature and spatial decomposition. Prior training is unrequired. The analysis of the reduction quality is performed by a side-to-side comparison between healthy and fractured sides. The pre-clinical validation of the technique consists of a two-stage study: Initially, we tested our algorithm with 14 healthy femurs, comparing the output with ground truth values. Then, a total of 140 virtual fractures was processed to assess the validity of our analysis of the quality of reduction. A two-sample t test and correlation coefficients between metrics and the degree of reduction have been employed to determine the reliability of the algorithm. RESULTS: The average detection error of landmarks was maintained below 1.7 mm and 2∘ (p< 0.01) for points and axes, respectively. Regarding the contralateral analysis, the resulting P-values reveal the possibility to determine whether a supracondylar fracture is properly reduced or not with a 95% of confidence. Furthermore, the correlation is high between the metrics and the quality of the reduction. CONCLUSIONS: This research concludes that our technique allows to classify supracondylar fracture reductions of the femur by only analyzing the detected anatomical landmarks. A initial training set is not required as input of our algorithm.

A Change in the Classical Order of Setting of Porous Metal Augments with Locked Cups in Hip Revision Surgery: Technical Note and Case Report.

Introduction: Reconstruction of acetabular bone defects by the combination of trabecular metal augments and porous cups can be complex when extensive bone loss and poor-quality bone exists. The onset of porous cups with an interlocking mechanism may simplify surgical technique due to its superior initial mechanical stability. We endorse the possibility for a change in the classical order of setting of the augments and the cup. Methods: We present a technical modification and a series of cases of three patients with Paprosky IIB and IIIA acetabular defects operated with a combination of porous metal augments and a porous cup. In all the three patients, the setting of the cup was done first and secured with locked screws, and then the augments were set in place as a wedge and fixed with screws in a standard fashion. Results: The postoperative X-ray showed good position of implants with restoration of the center of rotation, and the patients had good recovery. Radiological evaluation in the midterm follow-up did not show mobilization of implants. Discussion. The use of metal porous augments is widely used for severe acetabular defects, being a versatile system to adapt to the different size defects. Nevertheless, its use may be technically demanding and time consuming. It is not infrequent that the setting of the augments conditions the final position of the cup with a possible interference with initial stability and eventually bone ingrowth of the cup. The interlocking mechanism offers an additional biomechanical stability and thus may allow us to place the cup first in the desired position with a less demanding technique. Conclusion: With the use of locked-screw porous metal cups, the order of setting of implants may be changed in order to obtain a better restoration of the center of rotation and increased host-bone implant contact with a simplified surgical technique.

Automatic detection of landmarks for the analysis of a reduction of supracondylar fractures of the humerus.

An accurate identification of bone features is required by modern orthopedics to improve patient recovery. The analysis of landmarks enables the planning of a fracture reduction surgery, designing prostheses or fixation devices, and showing deformities accurately. The recognition of these features was previously performed manually. However, this long and tedious process provided insufficient accuracy. In this paper, we propose a geometrically-based algorithm that automatically detects the most significant landmarks of a humerus. By employing contralateral images of the upper limb, a side-to-side study of the landmarks is also conducted to analyze the goodness of supracondylar fracture reductions. We conclude that a reduction can be classified by only considering the detected landmarks. In addition, our technique does not require a prior training, thus becoming a reliable alternative to treat this kind of fractures.

New, Minimally Invasive, Anteromedial-Distal Approach for Plate Osteosynthesis of Distal-Third Humeral Shaft Fractures: An Anatomical Study.

BACKGROUND: Fractures of the distal third of the humeral shaft remain a challenge today. Plate osteosynthesis is the most commonly used method of treatment. Current minimally invasive plate osteosynthesis (MIPO) techniques applied to the distal part of the humerus have shown a high risk of radial nerve injury, and they are unable to adequately fix distal-most fractures. Our hypothesis was that using a new MIPO approach, distal humeral shaft fractures can be safely fixed. The aim of this study was to develop this new anteromedial-distal MIPO approach. METHODS: We conducted a laboratory descriptive study using 16 arms from adult human specimens. A new anteromedial-distal MIPO approach, starting distally through a small window in the pronator teres muscle, was developed. A premolded plate was introduced in the anterior side of the medial epicondylar area, through the anterior face of the humerus, up to the proximal part of the humeral shaft. Several anatomical parameters were measured on dissection to define the distances of the plate and screws to the neurovascular structures that could be at risk. RESULTS: The radial nerve was not at risk because of its pathway through the posterior and lateral aspects of the arm. The mean distance from the most distal border of the medial epicondyle to the proximal border of the coronoid fossa was 3.36 cm (95% confidence interval [CI], 3.23 to 3.50 cm). At least 3 screws could be inserted in all specimens in this area and up to 5 when the fixation area was extended 2 cm proximally. The mean width of the medial epicondylar area was 2.19 cm (95% CI, 2.03 to 2.33 cm), space enough for the distal fixation of the plate. The ulnar nerve was at risk only from the tip of the most distal screw (mean distance of 2.50 mm; 95% CI, 1.60 to 3.40 mm) in specimens with a very narrow medial epicondylar area. CONCLUSIONS: This approach provides adequate fixation for distal humeral shaft fractures, but proper clinical studies must be undertaken. CLINICAL RELEVANCE: This new approach avoids the risk of radial nerve injury.