Humerus

The Humerus is the longest Bone in the upper body with a structure that facilitates articulations at both The Elbow and The Shoulder Girdle . Consequently it forms the Glenohumeral Joint , Humeroradial Joint , Humeroulnar Joint and although not a true articulation theAcromiohumeral Interval.

Structure

Structure of the Humerus is often described in three segments; the shaft (diaphysis) and its two polar ends (epiphysis). The total length of the Humerus is reported to range between ~250-300mm (SOURCE-2).

Proximal Humerus

The Proximal Humerus consists Humeral Head, an anatomical neck, two Tuberosities (a Greater and a Lesser) and a Bicipital Groove which courses between them:

  • Humeral Head- the half-spheroid shaped Humeral Head forms the larger convex “ball” which articulates with the smaller concave Glenoid Fossa “socket”. At any point, the Fossa accounts for 25-30% of the surface area of the Humeral Head during articulation (SOURCE-6). Similarly, the depth of the Fossa is approximately 40% of the radius of the Humeral Head (SOURCE-6). The vertical length of the Humeral Head ranges between ~14mm to 17.5mm which accounts for less than 5% of the bones total length (SOURCE-2). The Humeral Head is lined with a thin articular Cartilage that ranges between 0.28-2.09mm and is thickest in a superior to inferior direction (SOURCE-3). In anatomical position the head is orientated medially and slightly superoposterior (SOURCE-7)

  • Anatomical Neck- the anatomical neck is the narrow continuity between the Humeral Head and Tuberosities and its the attachment site of the Glenohumeral Joint Capsule , medially/ distally the capsule extends roughly 1cm down the shaft (SOURCE-7)

  • Greater Tuberosity- is a bony protuberance that forms the lateral-most point of the proximal Humerus. The medial border is met by the Bicipital Groove . Serves as the attachment site for multiple muscles (listed below). A portion of the Tuberosity is often lined with Subacromial Bursa , distinguishing it from the overlying Deltoid (SOURCE-7)

  • Lesser Tuberosity- is a bony protuberance that forms the most anterior point of the Proximal Humerus. Its lateral border forms the medial side of the Bicipital Groove and superiorly serves as the attachment site for the Transverse Humeral Ligament . Surgical neck extends immediately distal of the Lesser Tuberosity (SOURCE-7)

  • Bicipital Groove - see page

Humeral Shaft

The middle ~60% (longitudinally) of the Humerus is considered the shaft, sporting no articulating surfaces. A cross-section of the shafts superior half resembles a circle whereas the distal half is more triangular in shape, forming the shafts three surfaces and three borders:

  • Posterior Surface - between the origin of the Lateral Head of Triceps and Medial Head of Triceps courses theRadial (or Spiral) Groovethat escorts the Radial Nerve as it descends obliquely towards the lateral border (SOURCE-7+20)

  • Anterolateral Surface - The proximal portion of this surface is featureless and covered by the Deltoid . Distal of the muscles attachment on theDeltoid Tuberosityat roughly the longitudinal midpoint, the Radial Nerve pierces the Lateral Intermuscular Septum to innervate the anterior compartment of the arm (SOURCE-7)

  • Anteromedial Surface - with exception to the Bicipital Groove , the superior half of this surface is smooth. In the middle-third of the bone, theBrachial Neuromuscular Sheathruns in close proximity to this surface. Roughly 5cm proximal of the Epicondyle, this surface also sports theSupracondylar Processwhich resembles a surfboard-fin and helps form a foramen that escorts the Median Nerve and Brachial Artery . The distal end is marked by the progressive extension of theMedial Supracondylar Ridgewhich serves as an attachment site for the Medial Intermuscular Septum (arm) (SOURCE-7)

Distal Humerus

Due to theMedial and Lateral Epicondylesthat extend from either side, the distal Humerus is wider on a medial-to-lateral axis than it is anterior-to-posterior. Each Epicondyle is accompanied by a ridge that is formed from the progressive expansion that extends from the shaft. The Medial Epicondyle has a slight posterior bias while the Lateral Epicondyle has a slight anterior bias. The distal end also features two articular surfaces and multiple fossae (SOURCE-7):

  • Lateral Capituluma convex projection that defines the anteroinferior surface of the lateral portion of the distal Humerus. The Capitulum articulates with the Head of Radius to form the Humeroradial Joint . The Capitulum does not extend posteriorly so the Radial Head is in contact anteriorly during Elbow - Flexion and inferiorly during Elbow - Extension

  • Medial Trochlea- defines the medal portion of the distal Humerus with an obliquely lateral bias as it extends posteriorly and articulates with the Trochlear Notch of Ulna to form the Humeroulnar Joint . While the Trochlea extends anteriorly-to-inferiorly-to-posteriorly the Ulna is only ever in contact with two of these surfaces, anteroinferiorly when in Elbow - Flexion and inferoposteriorly when in Elbow - Extension . The medial wall of the Trochlea is a bony projection that bears significant influence over the carrying angle of The Elbow . Laterally, the Trochlea is distinguished from the Capitulum by a faint groove

  • Olecranon Fossa- located just superior of the posterior Trochlea, reciprocates the Olecranon Process of Ulna at full Elbow - Extension

  • Coronoid Fossa- the smaller and anterior equivalent of the Olecranon Process that houses the anterior Coronoid Process of Ulna during full Elbow - Flexion

  • Radial Fossa- a slight bony depression above the Capitulum which houses the Radial Head in full Elbow - Flexion

Variation

Variations in Humeral morphology may be associated with genetic or developmental abnormalities or an adaptive response to overuse injury or disease:

Function

The Humerus plays an integral role in the structural stability of the Upper Limb , serving as the only bony link between The Shoulder Girdle and The Elbow . The extent to which the Humerus affords stability is contingent on its demands. As an example of adaptive response to greater stress, Tennis players had a 20% greater Humeral cross-sectional area on their dominant side (SOURCE-1). Conversely, an assumed decline in physical demand as we age may provide a possible explanation for the ~ 29% decline in areal bone mineral density between the ages of 30 and 80 (SOURCE-45).

Movement

As the longest bone the in upperbody, the Humerus acts as a lever to amplify forces produced at The Shoulder Girdle which acts as the fulcrum. As previously mentioned, the Humerus provides multiple articular surfaces for Glenohumeral Joint and The Elbow to facilitate the following movements:

Muscular Attachments

The Humerus is the attachment site for the following tissues in rough descending order:

Pathomechanics

The Humerus is subject to morphologies, injuries and diseases which may impact the health of the Bone , articulation at The Elbow and The Shoulder Girdle and neighbouring soft-tissues such as the Rotator Cuff .

Humeral Retroversion - Humeral Retroversion is the angular difference between the orientation of the Proximal Head of Humerus and the axis of The Elbow (SOURCE-9). As detailed on its page, the extent of Retroversion influences the range available to The Shoulder Girdle and the incidence of Glenohumeral Instability . While this variation may be the result of genetics or developmental abnormalities, it may also be an adaptive response to injury, overuse or degeneration. In either instance, this angular difference bares implications for the Rotator Cuff and Glenohumeral Joint Capsule . Similarly, variations such as a shallower Bicipital Groove or shorter Lesser Tuberosity may potentiate pathology of the Subscapularis and Long Head of Biceps (SOURCE-8).

Fractures

Fractures can occur at multiple sites along the Humerus:

Proximal Humeral Fractures

Fractures of the Proximal Humerus are the third most common fracture in those after 65, following distal Radius and The Hip (SOURCE-4+11). They account for 5-6% of all adult fractures, (SOURCE-16+23) with an average reported incidence of 82 per 100,000 person-years (114 female, 47 men), 2-3 fold more common in females (SOURCE-13+16+23+26). Fractures in this region can occur at one or several of the following sites (SOURCE-12):

  • Anatomical Neck

  • Surgical Neck - a constricted area distal of the Tuberosities that is the most frequently fractured site on the Proximal Humerus (SOURCE-16), accounting for roughly a quarter of its fractures (SOURCE-24).

  • Greater Tuberosity - account for ~ 10% of all Proximal Humeral Fractures, with half being associated with an Anterior Glenohumeral Dislocation (SOURCE-24)

  • Lesser Tuberosity

Multiple attempts have been made to classify fractures that occur at these sites, most notablyNeerand theAssociation of Osteosynthesis (AO)(SOURCE-12+17). The more recent and detailed AO classification divides Proximal Humeral fractures into three groups where the “part” refers to the amount of aforementioned sites that are damaged (SOURCE-18):

  • Group A (Extra-articular, Unifocal, 2-part) - a single displacement fracture of either the Tuberosity, Surgical Neck or a Vertical fracture that leaves the articular surface intact (SOURCE-26). These fractures account for roughly 66% of all Proximal Humeral Fractures (SOURCE-24)

  • Group B (Extra-articular, Bifocal, 3-part) - the displacement of two segments, usually associated with blood supply disruption (SOURCE-26)

  • Group C (Intra-articular or 4-part) - fracture of the Anatomical Neck that may or may not be associated withMetaphysealfracture. Usually associated with blood supply disruption (SOURCE-26)

In addition to the clustering of affected sites, Proximal Humeral Fractures can be distinguished for the deviation of the Humeral Head relative to the Shaft, which reflects the extent of damage to the Periosteum . These deviations can occur in the sagittal plane (anteriorly or posteriorly) or frontal plane as Valgus or Varus malposition, with frontal plane deviations being considerably more common (SOURCE-25). Valgus (posterolateral) deviations have a high association with another Proximal Humeral Fracture mechanism known as anImpaction Fracturewhere a traumatic axial load through the Upper Limb while in GH Joint - Abduction causes impaction of the Humeral Head within the Glenoid Cavity (SOURCE-14+25). Impaction fractures have been determined in studies to be Group A, B or C (SOURCE-14+29). As alluded to earlier, these fractures trend towards more favourable prognosis in terms of surgical reduction and Avascular Necrosis due to the relative preservation of the posteromedial Periosteum (SOURCE-14). Valgus Impaction Fractures are reported to account for 20% of all Proximal Humeral Fractures (SOURCE-24).

The majority of Humeral Fractures are associated with either a high-velocity traumatic episode in young men or a low-velocity traumatic episode in the elderly whose Bones may be vulnerable. For the Proximal Humerus specifically, a fracture is usually the result of a fall (most often obliquely forward) that results in direct impact on the fracture site (SOURCE-11). Given the traumatic onset, these fractures are often associated with Glenohumeral Dislocation ; however, their prevalence varies between studies from 4% of all Proximal Humeral Fractures to 19% (14% anteriorly, 5% posteriorly) (SOURCE-10+24+25+28).

Humeral Shaft Fractures

Fractures of the Humeral Shaft account for ~ 1-5% of all Fractures with a reported annual incidence of 13-20 per 100,000 persons (SOURCE-19+22). Akin to the Proximal Humerus, fractures to the Shaft have a bimodal age distribution where high incidence associated with high-impact trauma is seen in males between 21-30 followed by another peak incidence associated with low-impact trauma is seen in women over the age of 60 (SOURCE-19). The AO classification system assigns Humeral Shaft fractures to one of three groups (SOURCE-18):

  • Group A -Simplefractures that include, spiral, oblique (≥30º) and transverse (<30º) breaks. Oblique fractures in the proximal third of the shaft bear a greater risk of nonunion (SOURCE-19)

  • Group B -Wedgefractures that include intact or fragmentary wedges

  • Group C -Multifragmentary

Humeral Shaft fractures have a high union rate (>90%) that usually takes ~ 10 weeks; however, non-union increased significantly with age and in Group A fractures (SOURCE-19).

Distal Humeral Fractures

Despite occurring for roughly one-third of The Elbows Fracture s, Distal Humerus Fractures are considerably less common with an estimated prevalence of 5.7-13 per 100,000 person-years (SOURCE-21+33+38). Like other Humeral Fractures, Distal fractures share a bimodal age distribution with an initial peak in males aged 12-19 resulting from high-velocity trauma and another peak in elderly females from low-velocity falls (SOURCE-21+33). The AO classification system assigns Distal Humeral Fractures to one of three groups:

  • Group A -Extra-articularfractures that include an Avulsion Fracture , Simple, Wedge or Multifragmentary that leave the articular surface intact. Account for ~ 38.7% of all Distal Humeral Fractures (SOURCE-21)

  • Group B -Partial Articular- fractures that divide the surface with a Lateral or Medial sagittal plane or the Frontal/ Coronal plane in a manner that partially affects the articular surface. Account for ~ 24.15% of all Distal Humeral Fractures (SOURCE-21)

  • Group C -Complete Articular- articular surface is completely disassociated from the Humeral Shaft (SOURCE-18+21). Accounts for ~ 37.2% of all Distal Humeral Fractures (SOURCE-21)

Fracture Sequelae

Traumatic events often lead to anatomical changes in the Humerus which may predispose further injury, such as Glenohumeral Dislocation (SOURCE-10). Acutely these changes may represent edema of the Bone ; however, in chronic and/ or severe cases plastic deformation may ensue. If bone vascularity is compromised (as with Avascular Necrosis ) bleeding exudes into the surrounding space which may impede local soft-tissues. Further, over-lying soft-tissues are likely to be affected by the same traumatic event that lead to a fracture. This may serve as a possible explanation for the association between Humeral Fractures and Subacromial Bursitis or partial Rotator Cuff Tears (SOURCE-19). In the context of a fracture, local musculature may perpetuate displacement by translating the bony segments they attach to in the direction of their muscle vector (SOURCE-29).

Nonunion- another potential consequence of Fractures is a failure to adequately heal following either conservative or surgical management. While this may be attributed to infection, a lack of compliance with immobility or rehabilitation, malnutrition or other comorbidities, poor quality fixation remains the leading cause of nonunion following surgery (SOURCE-42).

  • Proximal Humeral Fractures- union rates vary between nonsurgical management and various surgical modalities and is heavily dictated by the type of fracture, patient demographic and surgeon experience (SOURCE-29+35)

  • Humeral Shaft Fractures- union rates following operative and nonoperative management reported to be up to 30% and 10%, respectively (SOURCE-20). Fractures occurring in the proximal-third of the Shaft, Oblique pattern or those with a considerable gap size at fracture site have a higher incidence of nonunion (SOURCE-22).

  • Distal Humeral Fractures- nonunion rates reported between 8-25% and are almost always treated with revision ORIF with bone graft (SOURCE-41+42). Symptoms include various types of Pain and poor Elbow function

Risk Factors

There are several factors that predispose the Humerus to injury:

  • Age- after the age of 40 the risk of a Humeral fracture increases exponentially with more than 70% of proximal fractures occurring in those over the age of 60 (SOURCE-11). Supporting this notion is a reported incidence of 200 per 100,000 person-years for those 60 and over, more than double that of the general population (SOURCE-26+13+16). Unsurprisingly, increased age also increases the likelihood of nonunion following a fracture (SOURCE-19). Osteoporosis is also highly associated with age, which predisposes the risk of fractures (SOURCE-43).

  • Sex- for the majority of Humeral Fractures a bimodal distribution is seen where males are more likely to experience fractures as adolescents/ in early adulthood, while females are more likely in their later years (50-60+) (SOURCE-11+13+16+21+23+26+33+19). This has at least in part been attributed to the incidence of Osteoporosis (SOURCE-42). While many risk factors for Osteoporosis are shared between sexes, low bodyweight and previous history of fracture appear to best define the sexual-dimorphism (SOURCE-42).

Pathology

The following pathologies may be related to the Humerus:

Rotator Cuff Tear and SLAP Lesion - through thickening of the Posterior Glenohumeral Joint Capsule , a more Retroverted Humerus may predispose a higher risk of injury, particularly in overhead throwers (SOURCE-44)

Osteoporosis - predisposes fractures of the Humerus (SOURCE-11+21). AFragility Fractureis considered when a Proximal Humeral Fracture is associated with Osteoporosis and a low-energy fall (SOURCE-16). These are considered tell-tale osteoporotic signs in lieu of imaging results.

Osteoarthritis - as the condition is primarily related to the degradation and inflammation of joints, the Humerus may be affected at its polar articular ends where it forms the Glenohumeral Joint and The Elbow .

Avascular Necrosis (AVN) - both the fracture causing traumatic event and surgery have the capacity to damage local vascular structures, disrupt blood supply and eventually lead to Bone degradation. Fractures at greatest risk of developing Humeral Head Ischemia are (SOURCE-26):

  • Metaphyseal Head Extension length - Calcar (Inferomedial Cortical between the Humeral Head and Surgical Neck) segment <8mm (SOURCE-27)

  • Medial Hinge Integrity - the medial/ inferior border of the Humerus remains intact

  • Fracture Patterns - Four part fractures at substantial risk (SOURCE-27)

Early surgical intervention within the first 48hrs significantly reduced the risk of AVN (SOURCE-26).

Glenohumeral Instability - recurrence of events, possibly leading to repeated Glenohumeral Dislocation . Instability has the capacity to predispose Proximal Humeral Fracture and vice versa.

Axillary Nerve Palsy - most commonly injured nerve following Fracture of the Proximal Humerus (SOURCE-16), in particular those associated with Anterior Glenohumeral Dislocation as it tractions the nerve on its posteroanterior course under the Glenoid Neck (SOURCE-26).

Radial Nerve Palsy - Humeral Shaft fractures may compromise neurovascular structures that course along it. The intimate course of the Radial Nerve within theSpiral Grooveof Humerus leaves it particularly susceptible to traction injury (SOURCE-20). Recovery is expected in the majority of cases without intervention (SOURCE-20).

Ulnar Nerve Palsy - a common complication of a Distal Humeral Fracture is injury to the Ulnar Nerve from the original traumatic event or surgical intervention (SOURCE-21). Preoperative Ulnar nerve symptoms are associated with ~ 25% of Group C fractures (SOURCE-21).

Adhesive Capsulitis - secondary Adhesive Capsulitis may arise in response to a fracture of the proximal humerus. Excessive immobility during the recovery/ bracing phase may predispose Frozen Shoulder (SOURCE-20)

Subacromial Impingement - Malunion of a Tuberosity on the Proximal Humerus following displacement may increase risk of impingement (SOURCE-29)

Triceps Brachii Tear - Open fractures of the Distal Humerus are often associated with large tears of the Triceps, which may indicate a Triceps-Splitting approach to surgery as the tissue is already compromised (SOURCE-21). Almost 10% of Distal Humeral Fractures are open (SOURCE-33)

Rotator Cuff Tears - have been associated with Humeral Fractures (SOURCE-19)

Subacromial Bursitis - has been associated with Humeral Fractures (SOURCE-19)

Assessment

Observation

  • Valgus or Varus deformity - may be visible following fracture to the Humeral Shaft. Typically Varus if the Fracture occurs distal of the Deltoid Tuberosity but may be Valgus if it occurs proximally (SOURCE-19)

  • Swelling/ Inflammation - may be present following a Fracture(SOURCE-12+19)

  • Greater External Rotation of the Humerus may be assumed following pathology of the Supraspinatus or Deltoid as the Long Head of Biceps attempts to compensate during GH Joint - Abduction

Range of Motion

For Proximal Humeral Fractures, motion of The Shoulder Girdle is most likely affected while for Distal Humeral Fractures The Elbow is. Motion may also occur at the site of nonunion (SOURCE-42):

Neurovascular

Assessment of the local neurovascular vessels may be relevant as they can be damaged following a Fracture of the Humerus , particularly from high-velocity trauma (SOURCE-19):

Imaging

The following details imaging techniques as they pertain to the Humerus:

Radiography (X-Ray)- are often the first line of imaging for all suspected Humeral Fractures as they are accessible and usually sufficient for the diagnosis (SOURCE-19+39). For all segments anAnteroposterior (AP) viewis relevant and aLateral viewfor Shaft and Distal Humeral fractures (SOURCE-19+21). Fractures of the Proximal Humerus may also benefit from aScapular Y viewand anAxillary viewfor suspected Tuberosity, Head-Split or Dislocation fractures (SOURCE-39). The fall-short of X-Rays is that overlying Bone may obstruct view, particularly with the Proximal Humerus. Additionally, this technique cannot provide information about the surrounding tissue which is often also implicated. The following region specific recommendations are also made:

  • Proximal Humerus

  • Humeral Shaft

  • Distal Humerus- AP View should be done with the patient in 40º Elbow - Flexion . If a Coronal Shear fracture is suspected a Lateral view is integral, with two distinct arcs, known as thedouble-arc signrepresenting a displaced Capitellum and Trochlea (SOURCE-41)

Magnetic Resonance Imaging (MRI)- with the capacity for Bone and Soft-Tissue to be implicated in Humeral Head pathology, MRIs may be preferable due to their ability to produce clear images of both. High sensitivity for the detection of edema also allows MRIs to recognise pathologies in their early phase (SOURCE-10). For suspected Shaft fractures, an MRI is suggested when concomitant damage to other tissues is suspected, such as when following high-velocity trauma (SOURCE-19)

  • Proton Density Weighted Images (PD)- localise bone and soft-tissue pathology at the same time. The high water content in inflamed tissue causes this tissue to appear white. Damage is somewhat proportional signs of edema and may serve as a predictor for concomitant conditions (SOURCE-10)

Computed Tomography (CT-Scan)- considered unnecessary and not recommend for acute fractures but may aid to confirm nonunion and its pattern, evaluate Bone stock/ quality or if pulses are affected (SOURCE-19+42). CT-Scans also have value for fracture classification and preoperative planning, particularly when a shear component is present (SOURCE-21+41). The advent of Three-Dimensional CT-Scan (3DCT) reconstructions have been shown to significantly improve sensitivity but not specificity for various fracture patterns and improved interobserver agreement of diagnosis of distal humeral fracture patterns (SOURCE-40)

Dual X-Ray Absorptiometry (DEXA)- is considered the gold-standard for the evaluation of Bone Mineral Density which serves a marker for Osteoporosis (SOURCE-47+48)

Three-dimensional Printing Technology (3DPT)- the creation of tangible 3D models from digital renderings may allow practitioners to have a more patient specific approach to diagnosis, treatment selection and application (SOURCE-39).

Palpation

  • The Lesser Tubercle can be distinguished from the Coracoid Process by palpating the anterior Head of the Humerus and simultaneously rotating the arm. The tubercle can be felt moving under the practitioners palpation (SOURCE-7)

Treatment

For Fractures, recommendations surrounding conservative treatment are contingent on the location and extent of damage:

  • Proximal Humeral Fracture~ 50% of these fractures can be treated nonoperatively as they are considered stable with have little to no displacement (SOURCE-15+25). These interventions have a reported success rate of 80-85% (SOURCE-23). Nonoperative treatment may be optimal for Surgical Neck Fractures such as Valgus-Impaction Fractures and 1 to 4-part minimally displaced fractures, although surgery becomes increasingly indicated with complexity (SOURCE-29). Minimal displacement has been defined as the following:

    • <1cm or <45º (SOURCE-23)

    • Less than 1/3rd the shafts diameter in any direction (SOURCE-25)

    • Greater than 5mm of a Tuberosity (SOURCE-25)

  • Humeral Shaft Fracture- Similarly, for Shaft fractures adequate Upper Limb function can be maintained with a 20º deviation in the sagittal (anterior) plane, 30º in the frontal plane (either direction), 15º of rotation or 3cm of shortening (SOURCE-19). This suggests a reasonable degree of flexibility in terms of displacement that can still be managed nonoperatively

  • Distal Humeral Fracture- Conversely, Distal Humeral Fractures often require surgery with nonoperative management indicated only when the fracture is completely undisplaced or where surgery is contraindicated (SOURCE-21). Only 30% of these fractures are handled nonoperatively (SOURCE-33)

Immobility of the Upper Limb with the support of a cast or splint is recommended for the initial 1-2 weeks until Inflammation subsides (SOURCE-19+20+29). After this period they may be progressed to a more mobile brace or sling which is sustained for roughly 8-12 weeks when fracture healing is confirmed by imaging or other means (SOURCE-20+33). Pain -free motion of The Shoulder Girdle , The Elbow and The Wrist should be re-introduced in a progressive manner from limited passive Range of Motion to active range of motion and eventually against resistance (SOURCE-49). Early range of motion interventions may lead to improved outcomes of function but should avoid aggravating the tissue healing process (SOURCE-21+49). Treatment/ Exercise progression is limited by the progress of the patients symptoms. While a degree of malunion/ restriction is not uncommon, this does not necessarily impede function and the restoration of Shoulder and Elbow Mobility is expected in the majority of Humeral fractures (SOURCE-19+21+37).

Myofascial Release

Given muscles have the capacity to become deforming forces in the context of a fracture, the patient may benefit from Myofascial Release techniques of relevant tissues (SOURCE-29). An understanding of actions and attachments of muscles local to the fracture site is required to effectively determine how a particular deforming force may be created.

Strengthening

Progressive resistance training is encouraged for those at risk of Fracture as it improves Bone Mineral Density, health-related quality of life, functionality and symptoms of Pain (SOURCE-50). Furthermore, routine exercise interventions such as resistance, Core or Balance training significantly reduce the risk of fall, a leading cause of Humeral Fracture (SOURCE-51)Initial Phase - main focus is the restoration of movement without provoking injury repair

Mid-Phase - the progression of load and volume has significant Osteogenic effect in both the young and old (SOURCE-52). Once Bone healing is well underway, training should progressively introduce greater loads (over 60% of one repetition maximum) and emphasise the eccentric component to promote Bone mass/ mineral density which will require a decrease in repetitions (SOURCE-52). A variety of exercises should also be employed.

Late Phase - the continued pursuit of Strength and Range of Motion can be complimented by exercises that are increasingly intense or reflective of the patients functional demands:

  • Plyometrics - induces significant bone formation which increases bone mass through the use of explosive movements (SOURCE-52). These movements bestow significant (often axial) loads through the Humerus which may reach the equivalent of multiple bodyweights (SOURCE-52). Relevant plyometric exercises for the Humerus include the following:

  • Later Phase Push Exercises:

Mobilisations

While any Mobilisation of The Shoulder Girdle or The Elbow has the capacity to infleunce the Humerus, the following lists those techniques that can be applied directly to either the proximal or distal Humerus: Joint Play - techniques applied with the patient at rest

Mobilisation with Movement - techniques applied through an affected motion

When a Radiculopathy is suspected, mobilisations may also be applied to the Cervical Spine with relevant techniques listed on its respective page.

Surgery

The jury remains out as to whether surgical interventions provide any additional benefit when compared to nonsurgical management for Fracture s. A recent high-quality review compared several surgical techniques with conservative alternatives for function, physical/ mental parameters and Pain anywhere from 3-24 months post injury to conclude no significant difference (SOURCE-37). Surprisingly, this conclusion remained the same when controlling for age or tuberosity involvement (fracture type) (SOURCE-37). With potentially negligible differences between the two perspectives surgical-hesitancy may be reinforced by the potential for surgical-complications such as infection, loss of fixation and Nerve Palsy (SOURCE-20+37). Additionally, high-revision rates are often due to Avascular Necrosis (SOURCE-15).

Despite conservative treatment being considered the gold-standard, in severe or complicated (multi-part) cases it may not be sufficient. For example, vascular damage requiring repair or bypass is an absolute indication for surgery (SOURCE-19). The following describes common surgical procedures for Humeral Fracture s:

Open Reduction and Internal Fixation (ORIF)- an incision is made through the overlying skin and soft-tissue to reveal the fracture site. The bone fragments are then repositioned (reduced) and then fixed with metal plates, screws or nails. Fixed-angle locking plates have considerable ability to secure comminuted and/ or osteoporotic Bone ; however, with increased complexity/ parts is a reduction in confidence of outcome (SOURCE-29). This procedure is often the method of choice for Proximal, Shaft and Distal Humeral fractures due to high union rates and relatively low complications (SOURCE-20-22-26):

  • Proximal Humeral Fractures- Locking Plates account for ~ 80% of all surgical interventions treating fractures in this region (SOURCE-37). Complications following ORIF increased significantly with age and fracture type, with Ischemic Head Necrosis associated with 3-35% of these interventions (SOURCE-26). Further, ORIF boasted significantly higher complication and revision rates when compared to an Arthroplasty in the elderly (SOURCE-15+29) and are not recommended in the elderly or immobile (SOURCE-26). On the other hand ORIF is indicated for the more active or young, particularly those that present with the following (SOURCE-16+19+26):

    • 2, 3 or 4-part Fractures

    • Head-Splitting Fractures

    • Vascular Damage that requires repair

    • Intra-Articular Extension- fracture that protrudes into the joint space

  • Humeral Shaft Fractures- ORIF is the preferred method of surgical treatment for fractures in these region, particularly for the young, accounting over half of all surgeries (SOURCE-33). The union rate is high (87-96%), taking an average of 12 weeks, while the complication rate is reported between 5 and 25% (SOURCE-19). Nerve palsy is the most common complication at 7% of patients, followed by infection at 3% (SOURCE-33)

  • Distal Humeral Fractures- remains the preferred method for intra-articular fractures and may be a valid treatment for comminuted or Osteoporotic Bone (SOURCE-32+21+42) with Dual Plate Fixation boasting a reported 89-100% union rate (SOURCE-21). When compared to fixation through wires and screws, Plate Fixation reported three-fold fewer poor outcomes (SOURCE-21). Parallel plating required less fixation revision but slightly greater complications such as wound dehiscence, neuropathy or implant prominence (SOURCE-32). There was a reported overall complication rate of 53% and reoperation rate of 21% following ORIF of the Distal Humerus (SOURCE-32)

Arthroplasty- Shoulder reconstruction may be relevant to Proximal Humeral Fractures while Elbow reconstruction may be relevant to Distal Humeral Fractures:

  • Shoulder Reconstruction - a prosthetic replaces either the Humeral Head alone (Hemiarthroplasty) or additionally the Glenoid Fossa (Reverse Total Shoulder Arthroplasty) which may be more favourable in older patients due to less revision rates (SOURCE-15). These interventions tend to be recommended for more severe fractures with greater displacement, comminution and/ or Rotator Cuff compromise or in those with poor bone quality such as the elderly (SOURCE-16+37). Following a displaced Proximal Humeral Fracture, aHemiarthroplastyis the second most common surgical treatment, accounting for ~ 10% (SOURCE-37)

  • Elbow Reconstruction - may be preferable for elderly patients with a displaced, comminuted or intra-articular fractures (SOURCE-21). Additionally, forCoronal Shear Fractures(Group B3) Elbow Arthroplasty may boast better functional outcomes in the long term for those over 65 years of age (SOURCE-21).

Intramedullary Nailing (IMN)- A permanent rod or “Nail” is inserted into the centre of the Bone . This implant is load-sharing while minimising disruption to local biology/ blood supply (SOURCE-20+22). Additionally, Nailing requires smaller incisions when compared to plating techniques which would suggest an extent of damage mitigation (SOURCE-20). This procedure may be more difficult to perform and is more suited for young, non-osteoporotic Bone (SOURCE-29).

  • Proximal Humeral Fracture- indicated for Surgical Neck fractures, 2, 3 and 4-part fractures (younger patients), combined Proximal Humerus plus Shaft fractures, and pathological fractures of the Shaft (metastase) (SOURCE-16+19+29). Despite boasting similar outcome measures to Locking Plate Fixation, IMN is not the primary choice for acute non-pathologic Proximal Humeral Fractures (SOURCE-29+35)

  • Humeral Shaft Fracture- reported union rates of 86-100% and complications such as Radial Nerve Palsy and Infection ranging from 6-100% (SOURCE-19), similar to that of Plate Fixation (SOURCE-22). Due to damage to overlying tissues such as the Rotator Cuff and/ or Long Head of Biceps from nail insertion, IMN does however present significantly greater risk of shoulder complications and reoperation (SOURCE-22). Local scar tissue that forms in response to the phenomenon may even predispose further injury such as Subacromial Impingement (SOURCE-20)

Closed Reduction and Percutaneous Pinning (CRPP)- the Humeral fragments are fixed using pins which are then removed 4-6 weeks later. This procedure is indicated for 2 and 3-part Surgical Neck fractures, such as Impaction fractures, for patients who have good Bone quality, an intactMedial Calcarand minimalMetaphysealdamage (SOURCE-16+29). The general consensus is that CRPP is less invasive than other techniques but also less precise.

  • Proximal Humeral Fracture- biomechanical studies have found CRPP to be inferior to ORIF; however, the use of larger or additional pins may increase stability (SOURCE-29). CRPP has displayed substantially higher complication rates (28.4%) including malunion, pin migration, infection, nerve palsy, soft tissue damage than other common surgical interventions (SOURCE-29)

  • Distal Humeral Fracture- for the young CRPP may reduce the time to restored motion at The Elbow and fewer complications when compared to open treatment; however, CRPP may not be sufficient for intra-articular (Group B or C) fractures (SOURCE-30)

Other

The following details novel surgical techniques or variations that have displaced early promise:

  • Minimally Invasive Plate Osteosynthesis (MIPO)- minimises soft-tissue damage with the aims of preserving the local biological environment with preliminary studies suggesting lower risk of non-union than ORIF (SOURCE-34). Radial Nerve palsy is a common complication (SOURCE-34)

  • 3D Printing Assisted Surgery- a preliminary review and meta-analysis concluded this technique reduces operation time, blood loss, time to union and complication rates while improving the reduction rate in Proximal Humeral Fractures (SOURCE-36+38)

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