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In elbow stiffness, pre-operative assessments should identify the articular and peri-articular tissues involved and, more specifically, they should determine how preserved the articular surfaces and osteo-articular congruity are.

Background: Correct sizing is challenging in radial head replacement and no consensus exists on the implant’s optimal height and width to avoid elbow stiffness and instability. Studies exists, suggesting how to appropriately choose the implant size, but the manner by which the fracture pattern influences the surgeons’ operative choices was not investigated. Methods: The radial heads of four fresh-frozen cadaveric specimens were excised, measured, and fractured to simulate four patterns: three fragments (A); four fragments (B); comminuted (C); comminuted with bone loss (D). Nine examiners were asked to indicate first the maximum diameter of the radial heads with the help of dedicated sizing dishes and then the appropriate implant size with trial implants. Accuracy and precision were determined. A coefficient of variation was calculated and agreement was evaluated with the Bland–Altman method. Results: Accuracy and precision of radial head diameter estimation with dedicated sizing dish were 96.73% and 93.64%, (best pattern, D; worst, C). Accuracy and precision of radial head diameter estimation with trial implants were 99.71% and 90.66% (best pattern, A; worst, D). Frequent modifications occurred between the initial radial head size proposal based on the sizing dish and the radial head size chosen after use of the trial implants (47.2%). Conclusions: Diameter estimation of radial heads with dedicated sizing dishes may be underestimated in comminuted fractures; when bone loss is present, this may lead to an overestimation, especially when using trial implants. Care is essential to determine the optimal size of the implant and to avoid overlenghtening and oversizing, which can be responsible for implant failure. Level of Evidence: Basic Science Study. Clinical Relevance: Knowledge of the manner by which the fracture pattern influences radial head replacement size estimation can help preventing overlenghtening and oversizing during this procedure.

Massive rotator cuff tears are defined as irreparable when tendon-to-bone or tendon-to-tendon continuity with the adducted arm cannot be restored and severe muscle fatty infiltration is present. Tendon transfer is a palliative procedure that improves shoulder function and relieves pain.

The incidence of complex articular fractures of the distal humeral in adults has increased and will be growing in the future due to the greater incidence of high energy trauma and to the higher percentage of elderly population. Successful treatment is challenging for the needed balance between a stability of often comminuted fracture and early motion.

The post-traumatic stiff elbow is a challenge for the surgeon, requiring expertise for the treatment choice and accurate planning. Stiffness can result from traumatic injury involving the periarticular soft tissues and the joint articular surfaces. In this article we want to assess the impact of three-dimensional printed models in selecting the appropriate surgical strategy for this pathology.

Radial nerve entrapment is an uncommon diagnosis. The entrapment can occur at any location within the course of the nerve distribution, but the most frequent location of entrapment occurs around the elbow and involves the posterior interosseous nerve.

The management of residual elbow instability is challenging in both acute and chronic injuries. Among the available devices, the hinged external fixator provides an additional joint stabilization while allowing an early motion but it clumsy and associated to high rate of pin track complications. To address these issues, an internal joint stabilizer (IJS) has been recently developed. An easier recreation of the axis of rotation coupled to the reduced lever arm of the hinge are the roots of the consistent and satisfactory results thus far observed. In addition, the device is more comfortable for the patients being an internal stabilizer. Nonetheless, a second surgery for the device removal is necessary of which the timing is still not standardized. This current concepts paper describes literature regarding outcomes of the IJS focusing on the rate of maintained radiographic joint reduction, the resultant range of motion and the associated complication profile.

In the forearm, posttraumatic heterotopic ossification usually forms as a proximal radioulnar synostosis. It can occur after soft tissue injury involving the interosseous membrane or after surgery involving the radio and ulna, such as distal biceps tendon repair. It can also be induced by radial head dislocation or fracture. Screening radiography can be used to select the appropriate time for excision. The synostosis can be resected when the ectopic bone margin and trabeculation appear mature on radiographs. An interval of 6–12 months from the injury is generally recommended based on ectopic bone maturity. Selection of the surgical approach depends on site, extension (elbow joint or proximal radioulnar joint), severity of the initial articular surface, and periarticular tissue injury. The posterolateral approach is indicated for synostoses: at or distal to the bicipital tuberosity, at the level of the radial head, and proximal radioulnar joint. The posterior global approach is recommended when the forearm synostosis is associated with complete bony ankylosis of the elbow involving the distal aspect of the humerus. After surgical resection of a proximal radioulnar synostosis, the exposed bone surfaces can be covered with interposition material to minimize recurrence.

The incidence of complex articular fractures of the distal humeral in adults has increased and will be growing in the future due to the greater incidence of high energy trauma and to the higher percentage of elderly population. Successful treatment is challenging for the needed balance between a stability of often comminuted fracture and early motion.

The elbow is a joint extremely susceptible to stiffness, even after a trivial trauma. As for other joints, several factors can generate stiffness such as immobilization, joint incongruity, heterotopic ossification, adhesions or pain. Prolonged joint immobilization, pursued to assure bony and ligamentous healing, represents the most acknowledged risk factor for joint stiffness.

In imperfect-information games, a common assumption is that players can perfectly model the strategic interaction and always maintain control over their decision points. We relax this assumption by introducing the notion of limited-control repeated games. In this setting, two players repeatedly play a zero-sum extensive-form game and, at each iteration, a player may lose controlover portions of her game tree. Intuitively, this can be seen as the chance player hijacking the interaction and taking control of certain decision points. What subsequently happens is no longer controllable–or even known–by the original players. We introduce prunedfictitious play, a variation of fictitious play that can be employed by the players to reach an equilibrium in limited-control repeated games. We motivate this technique with the notion of limited best response, which is the key step of the learning rule we employ. We provide a general result on the probabilistic guarantees of a limited best response with respect to the original game model. Then, we experimentally evaluate our technique and show that pruned fictitious play has good convergence properties.

A team game is a non–cooperative normal–form game in which some teams of players play against others. Team members share a common goal but, due to some constraints, they cannot act jointly. A real–world example is the protection of environments or complex infrastructures by different security agencies: they all protect the area with valuable targets but they have to act individually since they cannot share their defending strategies (of course, they are aware of the presence of the other agents). Here, we focus on zero–sum team games with nplayers, where a team of n - 1 players plays against one single adversary. In these games, the most appropriate solution concept is the Team–maxmin equilibrium, i.e., the Nash equilibrium that ensures the team the highest payoff. We investigate the Team–maxmin equilibrium, characterizing the utility of the team and showing that it can be irrational. The problem of computing such equilibrium is NP–hardand cannot be approximated within a factor of 1nε. The exact solution can only be found by global optimization. We propose two approximation algorithms: the former is a modified version of an already existing algorithm, the latter is a novel anytime algorithm. We computationally investigate such algorithms, providing bounds on the utility for the team. We experimentally evaluate the algorithms analyzing their performance w.r.t. a global optimization approach and evaluate the loss due to the impossibility of correlating.

Over the past 2 decades, the indications for total elbow arthroplasty have increased for acute and chronic pathologies. One complication following total elbow arthroplasty that is well recognized but is poorly described in the literature is the insufficiency of the extensor mechanism. During the last 3 years we have been using a modified triceps approach for total elbow arthroplasty using the anconeus-triceps lateral flap approach. This new approach preserves the proper triceps tendon medial insertion, and the lateral triceps, maintaining the continuity with the anconeus muscle as a flap single unit, is released and reflected proximally. This links the advantage of the triceps-preserving exposure (preserving the proper medial triceps tendon insertion) with the advantages of the triceps-splitting or triceps-reflecting exposures (better surgical exposure of the olecranon surface). It can be performed with the linked and unlinked total elbow prosthesis or with distal humeral hemiarthroplasty commercially available. Patients are able to perform light functional activity immediately postoperatively because the medial proper triceps insertion is preserved. The aims of this study are to describe the anatomic aspects of the triceps tendon insertion and to describe the surgical steps of the anconeus-triceps lateral flap approach used in total elbow arthroplasty.

Open reduction and internal fixation is the gold standard for the operative treatment of intra-articular distal humeral fractures. However, in elderly patients the approach involves a high rate of complications.