ABOS Part I & AAOS OITE Orthopaedic Surgery Review: AC Joint, Greater Tuberosity & Humeral Shaft Fractures | Part 21542

Correct Answer: C

The case describes a Rockwood Type III injury. According to the Rockwood classification system, a Type III injury involves complete tears of both the acromioclavicular and coracoclavicular ligaments. The clavicle is significantly displaced superiorly, typically demonstrating a 25 to 100 percent increased coracoclavicular distance. In this patient, the coracoclavicular distance increased from 10 mm to 20 mm, representing a 100% increase, which falls within the Type III criteria. Furthermore, the deltotrapezial fascia remaining intact is a key distinguishing feature of Type III compared to Type V, where it is extensively stripped. Type II involves a complete tear of the acromioclavicular ligaments with intact coracoclavicular ligaments and less than 25% increase in coracoclavicular distance. Type IV involves posterior displacement of the clavicle into the trapezius, requiring an axillary lateral radiograph for diagnosis, which is not indicated here. Type V involves severe superior displacement exceeding 100% of the normal coracoclavicular distance and extensive stripping of the deltoid and trapezius fascia, which is not described as stripped in this case.

Correct Answer: C

The case explicitly states under the 'Static Stabilizers' section: 'Biomechanically, the acromioclavicular ligaments provide the primary restraint to anterior-posterior horizontal translation of the clavicle on the acromion. Sectioning the superior acromioclavicular ligament results in profound horizontal instability.' The conoid and trapezoid ligaments (coracoclavicular ligaments) are crucial for vertical stability. The coracoacromial ligament is not a primary stabilizer of the AC joint itself, and the articular disc's role in stability is minimal, especially given its degeneration with age.

Correct Answer: B

The case highlights the ISAKOS Upper Extremity Committee's subclassification of Type III injuries into Type IIIA (vertically unstable but horizontally stable) and Type IIIB (vertically and horizontally unstable). The consensus suggests that Type IIIA injuries are best managed non-operatively, while Type IIIB injuries, characterized by dynamic overriding of the clavicle on the acromion during cross-body adduction, often experience poor functional outcomes with conservative care and may benefit from early surgical stabilization. This patient is a manual laborer (overhead athlete/manual laborer are indications for surgery in Type III) and presents with dynamic overriding during cross-body adduction, which is characteristic of a Type IIIB injury. Since the injury is acute (implied by 'after a fall' and not stated as chronic), acute suspensory cortical button fixation is the appropriate surgical technique. Chronic biologic reconstruction is for injuries presenting after six weeks. Distal clavicle excision is typically for chronic osteolysis or arthrosis, not acute instability. Non-operative management is generally for Type IIIA or less demanding patients with Type III.

Correct Answer: B

The case states that a 'Standard trauma series of the shoulder should be obtained, including a true anteroposterior view, a scapular Y view, and an axillary lateral view.' It further emphasizes that 'The axillary lateral is absolutely critical for identifying the posterior clavicular displacement characteristic of a Rockwood Type IV injury.' For optimal visualization of the AC joint itself, the 'most sensitive imaging modality for evaluating the acromioclavicular joint is the Zanca view. This is obtained by tilting the X-ray beam 10 to 15 degrees cephalad and reducing the penetrance by 50 percent compared to a standard shoulder anteroposterior radiograph.'

Correct Answer: C

Under the 'Acute Injury Management' section, the case states: 'Coracoid Preparation: The base of the coracoid is exposed. Using fluoroscopic guidance or arthroscopic visualization, a guide pin is placed centrally at the base of the coracoid. It is critical to place this pin centrally to avoid eccentric drilling, which drastically increases the risk of iatrogenic coracoid fracture.' Eccentric drilling, multiple drill holes, or drill holes exceeding 4mm in diameter are all identified as etiologies for coracoid fracture in the 'Complications' table. Avoiding fluoroscopy would increase the risk of malposition, and drilling before exposure would be unsafe.

Correct Answer: C

The case clearly differentiates between acute and chronic injury management. For chronic injuries, it states: 'Chronic injuries, presenting after six weeks, lack this healing potential and require biologic augmentation, typically in the form of autograft or allograft tendon reconstruction.' It further specifies: 'Because biologic grafts require months to incorporate, they must be protected with concurrent mechanical fixation.' The Weaver-Dunn procedure is described as providing only 20-30% of native load to failure, making it inferior to anatomic reconstructions. Meticulous deltotrapezial fascial closure is highlighted as 'arguably the most critical step of the procedure' regardless of technique. Distal clavicle excision is typically for osteolysis or arthrosis, not the primary goal of chronic instability reconstruction.

Correct Answer: C

The patient's symptoms of persistent pain localized to the distal clavicle with lucency and erosion on radiographs six months postoperatively are classic signs of distal clavicle osteolysis. The 'Complications and Management' table in the case describes 'Distal Clavicle Osteolysis' with an etiology of 'Micro-motion, rigid fixation (hook plates), or unrecognized intra-articular damage.' The recommended salvage strategy is 'Arthroscopic or open distal clavicle excision (Mumford procedure) once the coracoclavicular ligaments have fully healed.' The other options describe different complications with distinct presentations and management strategies.

Correct Answer: C

The 'Post Operative Rehabilitation Protocols' section outlines Phase One (Immobilization) from postoperative day zero to four weeks. During this phase, 'The patient is placed in a shoulder sling with an abduction pillow. The sling must support the weight of the arm to prevent inferior traction on the scapula... Active range of motion of the elbow, wrist, and hand is encouraged immediately... Pendulum exercises may be initiated at two weeks, but active shoulder elevation and reaching across the body are strictly prohibited.' Therefore, initiating active shoulder elevation at 3 weeks would be a violation of the protocol.

Correct Answer: C

Under the 'Neurovascular Anatomy' section, the case states: 'When performing coracoid dissection, surgeons must remain acutely aware of the musculocutaneous nerve, which enters the conjoint tendon approximately 3 to 5 centimeters distal to the coracoid tip, and the underlying brachial plexus, which sits posteromedial to the coracoid base.' Dissection extending too far distally and medially from the coracoid tip would directly endanger the musculocutaneous nerve as it enters the conjoint tendon. The axillary and suprascapular nerves are typically at risk more posteriorly or superiorly, respectively. The lateral pectoral nerve innervates the pectoralis major and is generally more superior and medial. The thoracoacromial artery is a vascular structure, not a nerve, and while important for hemostasis, the question specifically asks for a neurovascular structure at risk in this specific location, with the musculocutaneous nerve being the most prominent neural structure in that immediate vicinity.

Correct Answer: C

The 'Summary of Key Literature and Guidelines' section discusses the ISAKOS consensus guidelines for Type III injuries: 'The committee subclassified Type III injuries into Type IIIA (vertically unstable but horizontally stable) and Type IIIB (vertically and horizontally unstable). The current consensus suggests that Type IIIA injuries are best managed non-operatively, while Type IIIB injuries, characterized by dynamic overriding of the clavicle on the acromion during cross-body adduction, often experience poor functional outcomes with conservative care and may benefit from early surgical stabilization.' Option C describes a manual laborer (high-demand patient) with a Type IIIB injury (dynamic overriding), which is the specific indication for early surgical stabilization according to ISAKOS. Options A, B, D, and E either describe Type IIIA injuries, patients with contraindications to surgery, or patients with less demanding lifestyles where non-operative management is preferred.

Correct Answer: C

The case explicitly states that greater tuberosity fractures are frequently associated with other shoulder injuries, most notably anterior glenohumeral dislocations, occurring in 20-30% of cases. This makes anterior glenohumeral dislocation the most commonly observed associated injury among the options provided. While rotator cuff tears can be concomitant or cause the avulsion, and brachial plexus injuries can occur, they are not as frequently noted as anterior dislocations in the context of GT fractures. Humeral shaft fractures and posterior glenohumeral dislocations are less common associations.

Correct Answer: D

The case details the surgical anatomy of the greater tuberosity, stating that the supraspinatus inserts on the superior facet. Its primary action is abduction of the humerus, and its unopposed pull is the main driver of superior displacement in greater tuberosity fractures. The infraspinatus inserts on the middle facet and the teres minor on the inferior facet, both contributing to external rotation. The subscapularis inserts on the lesser tuberosity, and the deltoid is not a rotator cuff muscle, inserting more distally on the humerus.

Correct Answer: C

The case explains that a superiorly displaced greater tuberosity fragment can lead to mechanical impingement against the acromion during abduction, causing pain and limiting range of motion. This is a direct biomechanical consequence of the superior migration. While avascular necrosis (AVN) is a concern with humeral head fractures, it is rare for isolated greater tuberosity fractures. Chronic anterior glenohumeral instability is more associated with anterior displacement or recurrent dislocations. Isolated external rotation weakness would be more likely with significant posterior displacement. Accelerated glenohumeral osteoarthritis can be a long-term sequela of chronic impingement and altered kinematics, but mechanical impingement and reduced abduction are the more immediate and direct functional consequences of a superiorly malunited fragment.

Correct Answer: C

The case states that operative management is indicated for displaced fractures, specifically mentioning superior displacement greater than 3-5 mm. With 4mm of superior displacement, this fracture falls within the surgical indication range. Furthermore, the patient is described as an 'active tennis player' with 'high functional demands,' for whom optimal restoration of shoulder mechanics is paramount. Non-operative management is typically reserved for minimally displaced fractures (<3-5mm). Arthroscopic debridement and capsular release are treatments for adhesive capsulitis, not acute fractures. Hemiarthroplasty is an extreme measure for severe, complex fractures or arthrosis, not an isolated GT fracture. Delayed ORIF is generally not recommended as early anatomical reduction is crucial for optimal outcomes.

Correct Answer: C

The case explicitly states that a Computed Tomography (CT) scan with 3D reconstructions is 'essential' for displaced greater tuberosity fractures. It provides detailed information regarding fragment size, shape, number, precise degree and direction of displacement, articular involvement, and comminution, which is critical for surgical planning. While MRI is indicated if there is suspicion of concomitant rotator cuff pathology or labral tears, it is not considered the primary essential imaging for characterizing the bony fracture itself. Ultrasound, arthrography, and dynamic fluoroscopy have more limited roles in initial detailed fracture assessment.

Correct Answer: C

The case specifically highlights the importance of limiting the deltoid split to approximately 5 cm distal to the acromial border when using the anterolateral approach. This is because the axillary nerve typically courses horizontally around the humerus at this level, and extending the split beyond this limit significantly increases the risk of iatrogenic nerve injury, which could lead to deltoid weakness or paralysis.

Correct Answer: B

The image depicts screws crossing the fracture line, which is characteristic of lag screw fixation. The case describes lag screw fixation as a technique where screws are placed across the fracture site in a lag fashion to achieve interfragmentary compression. This provides rigid fixation and excellent compression, which is advantageous for larger, single, well-corticated fragments. Tension band wiring typically involves wires, not screws. Neutralization plating uses a plate to protect screws from bending forces, which is not the primary principle shown. Suture anchor repair uses anchors and sutures, not screws, to reattach the rotator cuff footprint. Intramedullary nailing involves a rod placed within the medullary canal, which is not shown.

Correct Answer: C

The patient's symptoms of progressive, diffuse shoulder pain and a global loss of both active and passive range of motion, despite adherence to rehabilitation and with satisfactory fracture healing, are classic for adhesive capsulitis (frozen shoulder). The case identifies this as a common complication after shoulder trauma and surgery, with aggressive physical therapy being the cornerstone of its management. Non-union would typically present with persistent pain and possibly instability, but not necessarily global loss of passive range of motion if the fracture is healing. A rotator cuff re-tear would cause weakness and pain, but not necessarily global loss of passive motion. Axillary nerve injury would primarily cause deltoid weakness and sensory deficits. Avascular necrosis is rare for isolated GT fractures and presents with progressive pain and stiffness, but the global loss of passive motion points more strongly to adhesive capsulitis.

Correct Answer: D

The case outlines the 'Protection Phase (0-6 Weeks Post-Op)' of rehabilitation, explicitly stating the restriction: 'NO active shoulder range of motion (AROM).' The goal during this phase is to protect the healing fracture. Pendulum exercises, passive range of motion for adjacent joints (elbow, wrist, hand), gentle isometric scapular retractions, and limited gravity-assisted PROM are generally permitted to prevent stiffness and maintain mobility without stressing the repair. Active shoulder motion would place undue stress on the healing fracture and rotator cuff repair.

Correct Answer: D

The 'Summary of Key Literature / Guidelines' section explicitly states, 'There is no single universally accepted 'best' fixation method.' It further elaborates that the decision often comes down to surgeon preference, fragment characteristics, and bone quality. Suture fixation is often preferred for smaller avulsion fragments or osteoporotic bone, but also for broad reattachment of the rotator cuff footprint. Screw fixation is suitable for larger, sturdy fragments. Plate fixation is less common for isolated GT fractures. Therefore, options A, B, and C represent oversimplifications or incorrect statements regarding the indications or contraindications of specific methods. Option E is also incorrect, as the role of arthroscopy is still an evolving concept, and it has not been definitively proven superior in all cases, nor is it suitable for all fracture types.

Correct Answer: C

The radiograph depicts a spiral or oblique fracture of the distal one-third of the humerus, consistent with a Holstein–Lewis fracture. The clinical presentation of numbness in the dorsal first web space and inability to extend the wrist and fingers is characteristic of a radial nerve palsy. The case description explicitly states that the Holstein–Lewis fracture is a specific spiral or oblique fracture of the distal one-third of the humerus, characterized by its high association with radial nerve injury (10-20% incidence). The sharp, displaced proximal fracture fragment uniquely predisposes the radial nerve to entrapment or direct laceration.

Option A is incorrect because Holstein–Lewis fractures are typically spiral or oblique, not transverse, and have a significantly high risk of radial nerve injury. Option B is incorrect as Holstein–Lewis fractures are associated with radial nerve injury, not typically median nerve injury, and are not primarily supracondylar in the classic sense of pediatric supracondylar fractures. Option D is incorrect as Holstein–Lewis fractures typically spare the articular surface. Option E is incorrect as the fracture is in the distal humerus, not the proximal humerus, and is not managed with shoulder arthroplasty.

Correct Answer: C

The case study emphasizes that in Holstein–Lewis fractures, the radial nerve is particularly vulnerable at the point where it pierces the lateral intermuscular septum and more distally, where it runs intimately with the periosteum of the distal humerus. This transition point, typically 10-14 cm proximal to the lateral epicondyle, is where the nerve moves from the posterior compartment to the anterior compartment of the arm, making it susceptible to entrapment or injury by the sharp, often medially displaced, proximal fracture fragment.

Option A describes a more proximal location, not specific to Holstein–Lewis vulnerability. Option B describes the vulnerability in mid-shaft fractures, not the unique vulnerability in Holstein–Lewis fractures which are more distal. Option D describes the nerve's course after it has already passed the critical zone of injury for Holstein–Lewis fractures. Option E describes the ulnar nerve's general vicinity, not the radial nerve.

Correct Answer: C

The case study explicitly states under 'Indications for Operative Management' that if a radial nerve palsy 'worsens or develops following closed reduction attempts,' immediate surgical exploration is mandatory. This scenario suggests iatrogenic injury or worsening entrapment of the nerve by fracture fragments. While many neuropraxias recover spontaneously, a worsening palsy after manipulation is a critical indication for immediate surgical intervention to decompress or repair the nerve and stabilize the fracture.

Option A is incorrect because worsening palsy post-reduction is an absolute indication for exploration, not observation. Option B (NCS/EMG) is not an emergent study and would delay critical intervention. Option D (functional brace and early ROM) is part of post-operative care, not the immediate management for a worsening nerve palsy. Option E (gabapentinoids for CRPS) is for a different complication and not the immediate concern.

Correct Answer: B

The case study states that the 'Posterior Approach (Triceps-Sparing or Triceps-Splitting)' is often the preferred approach for Holstein–Lewis fractures, particularly when radial nerve exploration is anticipated or required, as it provides excellent direct visualization of the fracture site and the radial nerve as it exits the spiral groove. The most crucial step is 'Radial Nerve Identification,' which involves identifying the nerve proximally in the spiral groove and tracking it distally to the fracture site, carefully inspecting it for injury or entrapment.

Option A (Anterolateral approach) can be used but is less preferred when direct radial nerve exploration is the primary indication. The musculocutaneous nerve is not the primary concern in Holstein–Lewis fractures. Option C (Medial approach) is not the standard for Holstein–Lewis fractures, and while ulnar nerve protection is important, it's not the primary nerve at risk in this specific fracture. Option D (Deltopectoral approach) is for proximal humerus fractures. Option E (Lateral approach) is not the primary approach, and the posterior interosseous nerve is a distal branch of the radial nerve, not the main site of vulnerability in this fracture pattern.

Correct Answer: C

The 'Summary of Key Literature / Guidelines' section explicitly states that 'Contemporary literature strongly supports the use of dual plating (e.g., orthogonal or parallel plate constructs) for displaced distal humeral shaft fractures, including Holstein–Lewis patterns. This provides superior biomechanical stability compared to single plating, especially against torsional and bending forces, which are critical for the oblique/spiral nature of these fractures.' It also recommends 'The use of lag screws across the oblique or spiral fracture line, prior to plate application, is highly recommended to achieve interfragmentary compression and increase construct stiffness.'

Option A (Single plate fixation) is less stable than dual plating for these fractures. Option B (Intramedullary nailing) is generally not preferred for distal humeral shaft fractures due to concerns about elbow impingement and less stable fixation in the metaphyseal region compared to plating. Option D (External fixation) is typically reserved for severe open fractures or temporary stabilization in polytrauma, not definitive fixation of closed Holstein–Lewis fractures. Option E (Tension band wiring) is more commonly used for avulsion fractures or olecranon fractures, not for diaphyseal/metaphyseal humerus fractures.

Correct Answer: C

The 'Post-Operative Rehabilitation Protocols' section for Phase 1 (0-2 Weeks) outlines the following: 'Gentle active-assisted ROM (AAROM) and passive ROM (PROM) of the elbow, typically 30-90 degrees of flexion/extension, initiated as soon as pain allows and dictated by surgical stability.' It also specifies 'Active and passive range of motion (ROM) exercises for the wrist, hand, and fingers' and 'Pendulum exercises, active-assisted shoulder flexion, extension, abduction, and rotation (within pain limits) to prevent shoulder stiffness.' It explicitly states 'No active biceps/triceps contractions against resistance' and 'Non-weight-bearing (NWB) for the operative extremity.'

Option A and E are incorrect as active resistance and advanced strengthening are contraindicated in the immediate post-operative phase to protect the fixation. Option B (complete immobilization for 6 weeks) is incorrect as early, protected motion is crucial to prevent elbow stiffness. Option D (unrestricted weight-bearing) is incorrect as the limb must be non-weight-bearing in this phase.

Correct Answer: C

The 'Complications & Management' section, under 'Non-Union,' states that management involves 'Revision ORIF with robust fixation (dual plating), debridement of fibrous tissue, interposition bone grafting (autograft or allograft), potentially electrical stimulation.' Given the persistent pain, instability, and radiographic non-union at 9 months, a surgical revision is indicated. The initial single plate fixation may have been inadequate, making dual plating a more robust option for revision.

Option A (observation and NSAIDs) is inappropriate for an established non-union. Option B (systemic antibiotics) is incorrect without evidence of infection (e.g., elevated inflammatory markers, wound drainage, positive cultures). Option D (external fixation) is generally not the definitive treatment for a non-union of the humerus unless there are severe soft tissue issues or active infection. Option E (tendon transfers) is a salvage procedure for chronic nerve palsy, not for fracture non-union.

Correct Answer: B

The 'Introduction & Epidemiology' section states that the 'typical mechanism of injury involves direct trauma or a low-energy torsional force to the arm.' The 'Surgical Anatomy & Biomechanics' section further clarifies that 'The biomechanics of Holstein–Lewis fractures often involve a combination of bending and torsional forces. The oblique or spiral nature of the fracture makes it inherently unstable to rotational loads, and the smooth, often comminuted, fracture surfaces can make stable reduction challenging.'

Option A describes a different mechanism and fracture pattern. Option C describes an olecranon fracture, not a Holstein–Lewis. Option D describes a supracondylar fracture, which is distinct from a Holstein–Lewis. Option E describes a proximal humeral fracture, not a distal one-third diaphyseal fracture.

Correct Answer: B

The 'Summary of Key Literature / Guidelines' section, under 'Immediate vs. Delayed Exploration,' clearly states: 'If a radial nerve palsy develops or worsens after attempts at closed reduction, or post-operatively, immediate surgical exploration is mandatory. This suggests iatrogenic injury or worsening entrapment.' This is a critical distinction from primary palsy (palsy at presentation), where immediate exploration is often recommended but sometimes observation is considered for incomplete palsies, though less common for classic Holstein-Lewis patterns due to high entrapment risk.

Option A is incorrect; secondary palsies are a red flag for iatrogenic injury and require immediate exploration. Option C reverses the urgency; secondary palsies are often more concerning due to their iatrogenic nature. Option D (immediate tendon transfers) is a salvage procedure for chronic, non-recovering palsy, not acute management. Option E is incorrect as the timing of palsy onset significantly impacts the management strategy.

Correct Answer: C

The 'Complications & Management' section, under 'Radial Nerve Palsy (Persistent/New),' states: 'If palsy persists >3-6 months post-injury: Consider secondary surgical exploration (neurolysis, repair, or grafting). Chronic palsy (>1 year): Tendon transfers (e.g., pronator teres to ECRB, FCR to EDC, palmaris longus to EPL) for functional restoration.' After 18 months with no recovery following nerve grafting, the likelihood of spontaneous or further surgical nerve recovery is very low, making tendon transfers the definitive functional salvage procedure.

Option A (repeat nerve grafting) is generally not indicated after 18 months of no recovery following a previous graft, as the window for nerve regeneration is typically considered closed or severely limited. Option B (chronic pain management) addresses symptoms but not the functional deficit. Option D (permanent immobilization) would result in a non-functional limb. Option E (electrical stimulation) is an adjunctive therapy, not a primary salvage strategy for a complete, chronic palsy.

Acceptable alignment criteria for functional bracing of humeral shaft fractures include <20 degrees of anterior bowing, <30 degrees of varus/valgus angulation, <15 degrees of malrotation, and <3 cm of shortening.

The superior acromioclavicular ligament is the thickest and most robust portion of the AC capsule, serving as the primary restraint to anteroposterior translation of the distal clavicle.

Multiple studies demonstrate that while union rates and functional outcomes are similar, intramedullary nailing of the humerus is associated with a significantly higher incidence of postoperative shoulder pain compared to plating.

The conoid ligament inserts approximately 4.5 cm medial to the distal end of the clavicle and acts as the primary restraint against superior translation of the clavicle.

In overhead athletes and high-demand laborers, the threshold for surgical fixation of a greater tuberosity fracture is >3 mm of superior displacement to mitigate the high risk of subacromial impingement and loss of elevation.

In a Holstein-Lewis fracture, the radial nerve is highly susceptible to entrapment or injury as it is relatively fixed where it pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment.

A Rockwood Type IV acromioclavicular injury involves posterior displacement of the distal clavicle into or completely through the deltotrapezial fascia, typically requiring surgical intervention.

In pediatric patients, AC joint "dislocations" are usually physeal separations (pseudodislocations). The distal clavicle tears through the superior periosteum, while the robust coracoclavicular ligaments remain attached to the intact inferior periosteal sleeve.

Transverse fracture patterns and proximal third locations have the highest rates of nonunion when treated non-operatively with a functional brace, largely due to distraction forces and poor soft tissue compression.

The axillary nerve runs transversely across the deep surface of the deltoid approximately 5 to 7 cm distal to the lateral edge of the acromion. The deltoid split must stay proximal to this to prevent nerve injury.

Primary radial nerve palsy in the setting of a closed humeral shaft fracture is managed non-operatively, as >70% spontaneously recover. Surgical exploration is indicated for open fractures, penetrating injuries, or secondary palsies that develop after closed reduction.

In active patients, superior displacement of the greater tuberosity of 5 mm or more is an indication for surgical fixation. Displacement greater than this predictably leads to subacromial impingement and altered rotator cuff biomechanics.

The coracoclavicular (CC) ligaments, comprising the conoid and trapezoid, are the primary restraints to superior and inferior translation of the clavicle. The AC capsular ligaments primarily resist anterior-posterior (horizontal) translation.

Acceptable alignment for humeral shaft fractures managed non-operatively includes up to 30 degrees of varus/valgus angulation, 20 degrees of anterior/posterior bowing, and 3 cm of shortening. Deformities within these parameters are generally well compensated by shoulder and elbow motion.

In the setting of anterior shoulder dislocation, an associated greater tuberosity fracture is inversely related to the presence of a rotator cuff tear. The failure occurs through the bone (avulsion) rather than the tendinous insertion of the rotator cuff.

The radial nerve passes through the lateral intermuscular septum from the posterior to the anterior compartment approximately 10 cm (range 9-12 cm) proximal to the radiocapitellar joint. It crosses the posterior humerus approximately 20 cm proximal to the medial epicondyle.

Intramedullary nailing of humeral shaft fractures is associated with a significantly higher rate of shoulder pain, impingement, and subsequent hardware removal compared to plate fixation. Plating carries a slightly higher risk of iatrogenic radial nerve palsy.

Posterior displacement of the distal clavicle into the trapezius defines a Rockwood Type IV injury. This is a high-energy injury that requires surgical reduction and stabilization due to extreme discomfort and the inability to reduce the clavicle closed.

In comminuted or osteoporotic greater tuberosity fractures, suture fixation incorporating the rotator cuff tendon (tension band principle) provides superior biomechanical stability. Isolated screws often fail via toggling and pullout in poor-quality cancellous bone.

Transverse fracture patterns and proximal third locations have the highest risk of nonunion when treated with functional bracing. Functional bracing relies on soft tissue envelope compression, which is less effective for transverse patterns and proximal lesions.

Biomechanical studies have shown that the CA ligament has only roughly 20-25% of the tensile strength of the native coracoclavicular (CC) ligaments. Therefore, modern variations usually augment the transfer with rigid fixation, sutures, or allograft reconstructions.

For fractures between the pectoralis major and deltoid insertions, the proximal fragment is adducted (by the pec major, latissimus, and teres major). The distal fragment is abducted and translated proximally by the deltoid.

Resection of greater than 1 cm of the distal clavicle can compromise the superior and posterior AC capsular ligaments, leading to anterior-posterior (horizontal) instability. Care must be taken to preserve these capsular structures during excision.

This patient has a 'floating elbow' (ipsilateral humerus and forearm fractures), which is an absolute indication for surgical stabilization (ORIF) of both the humerus and forearm. This allows for early mobilization and prevents severe joint stiffness.

The conoid ligament inserts posteromedially on the conoid tubercle of the clavicle and is the primary restraint to superior clavicular displacement. The trapezoid inserts anterolaterally and is the primary restraint to axial compression.

Posterior shoulder dislocations are classically associated with lesser tuberosity fractures (or reverse Hill-Sachs lesions) due to the avulsion pull of the subscapularis or direct impaction. Anterior dislocations are associated with greater tuberosity fractures.

In the setting of a humerus fracture with an ischemic limb, the standard sequence is to place a temporary intravascular shunt to restore perfusion, perform rigid skeletal fixation, and then perform definitive vascular repair.

A Rockwood Type VI AC joint injury involves inferior displacement of the distal clavicle into a subcoracoid or subacromial position. This is a severe, high-energy injury that invariably requires surgical reduction.

The supraspinatus tendon attaches to the superior facet of the greater tuberosity and provides a strong superior and medial deforming force. The infraspinatus and teres minor pull the fragment posteriorly.

Hypertrophic nonunions possess adequate biology but lack rigid mechanical stability. Therefore, they are best treated by providing stable mechanical fixation, typically with compression plating, without the strict need for bone grafting.

The trapezoid ligament inserts anterolaterally on the clavicle approximately 3 cm from the distal articular surface. The conoid ligament inserts posteromedially approximately 4.5 cm from the distal clavicle and acts as the primary restraint to superior translation.

In overhead athletes, greater tuberosity displacement of greater than 3 mm is often treated operatively to prevent symptomatic subacromial impingement and altered rotator cuff kinematics. For the general non-athlete population, the threshold for surgery is typically 5 to 10 mm.

Absolute indications for early radial nerve exploration in humeral shaft fractures include an open fracture with a nerve palsy, penetrating trauma, and a concomitant vascular injury requiring surgical repair. Primary palsies in closed fractures are typically observed initially.

A secondary (post-reduction) radial nerve palsy in the setting of a humeral shaft fracture is an absolute indication for surgical exploration. This presentation suggests the nerve may be entrapped within the fracture site following the reduction attempt.

The accepted deformity limits for successful non-operative management of a humeral shaft fracture using functional bracing are up to 30 degrees of varus/valgus angulation, 20 degrees of anterior/posterior bowing, and 3 cm of shortening.

Superior displacement of a greater tuberosity fracture greater than 5 mm is a widely accepted indication for surgical fixation. Failure to reduce the fragment can lead to severe subacromial impingement and altered rotator cuff biomechanics.

The conoid ligament inserts approximately 4.5 cm medial to the distal articular end of the clavicle and slightly posterior to the midline. The trapezoid ligament inserts approximately 3.0 cm medial to the distal clavicle and anteriorly.

Compared to compression plating, intramedullary nailing of humeral shaft fractures is associated with a significantly higher incidence of postoperative shoulder pain and impingement, as well as an increased overall reoperation rate. Plating carries a higher risk of iatrogenic radial nerve palsy.

Adhesive capsulitis (shoulder stiffness) is the most common complication following non-operative management of isolated, non-displaced greater tuberosity fractures. Early implementation of passive and active-assisted range of motion is crucial to prevent this.

A Rockwood Type IV injury is characterized by posterior displacement of the distal clavicle into or through the deltotrapezial fascia. This is an absolute indication for operative reduction and fixation, as closed reduction is generally unsuccessful.

The radial nerve pierces the lateral intermuscular septum approximately 10 cm proximal to the lateral epicondyle (radiocapitellar joint) as it courses from the posterior compartment into the anterior compartment of the distal arm.

If a primary radial nerve palsy fails to demonstrate clinical or EMG evidence of recovery by 3 to 4 months post-injury, surgical exploration of the nerve is indicated to assess for neurotmesis or severe entrapment requiring repair or grafting.

The clinical scenario describes an atrophic nonunion of the humeral shaft. The gold standard treatment involves open reduction, rigid internal fixation (typically with a compression plate), and the addition of autologous bone graft to provide the necessary biological osteogenic stimulus.