Surgical Management of Proximal Humeral Malunions: A Comprehensive Academic Guide

Comprehensive Introduction and Patho-Epidemiology

The surgical management of proximal humeral malunions represents one of the most formidable and technically demanding challenges within the entire spectrum of reconstructive shoulder surgery. These complex deformities arise when displaced fractures of the proximal humerus heal in non-anatomic positions, a scenario that frequently follows the nonoperative management of complex two-, three-, or four-part fractures, or as a sequela of failed primary osteosynthesis where loss of reduction has occurred. The resulting pathoanatomy is characterized by a devastating combination of distorted osseous architecture, profound and unyielding soft tissue contractures, severely altered glenohumeral and scapulothoracic biomechanics, and inherently compromised regional vascularity. Consequently, surgical intervention is highly complex, requiring meticulous preoperative planning and master-level execution to navigate the distorted anatomy safely.

Epidemiologically, the incidence of proximal humeral malunions is closely tied to the rising prevalence of osteoporotic proximal humerus fractures in the aging population. While the majority of minimally displaced fractures heal with acceptable alignment and function following conservative care, the threshold for acceptable displacement is frequently exceeded in frail patients deemed poor surgical candidates at the time of acute injury. Over time, the unopposed pull of the rotator cuff musculature exacerbates the initial displacement, leading to progressive deformity before osseous union is achieved. The primary goals of delayed reconstructive treatment are the alleviation of severe, intractable pain, the restoration of a functional range of motion, and the re-establishment of glenohumeral stability, though patients must be counseled that a return to pre-injury, perfectly normal kinematics is rarely attainable.

Decision-making in this arena must be highly individualized, taking into account a multitude of patient-specific and pathoanatomic variables. The surgeon must carefully weigh the patient's physiological age, functional demands, and medical comorbidities against the specific architectural distortion of the malunion (e.g., severe varus collapse of the surgical neck, superior or posterior migration of the greater tuberosity, or a combination thereof). Furthermore, the status of the rotator cuff musculature—often retracted, fatty-infiltrated, or structurally compromised—and the integrity of the articular cartilage are critical determinants in selecting the appropriate reconstructive pathway, which ranges from joint-preserving corrective osteotomies to complex anatomic or reverse total shoulder arthroplasty.

The chronicity of the malunion plays a pivotal, arguably paramount, role in determining the ultimate functional outcome, underscoring the necessity of early recognition and intervention. Landmark literature, notably the work of Beredjiklian et al., has demonstrated that a delay in operative treatment exerts a profound negative effect on surgical success. In their definitive analysis, 84% of patients treated less than one year after the initial injury achieved satisfactory functional outcomes. Conversely, only 55% of patients treated more than one year post-injury achieved similar results. This stark discrepancy is largely attributed to the progressive, irreversible nature of soft tissue contractures, capsular scarring, and the rapid onset of secondary degenerative changes within the glenohumeral joint over time, making early surgical intervention critical for joint preservation.

Detailed Surgical Anatomy and Biomechanics

Understanding the profoundly altered surgical anatomy and biomechanics of a proximal humeral malunion is the absolute prerequisite for successful preoperative planning and intraoperative execution. The normal proximal humerus is characterized by a neck-shaft angle ranging from 130 to 140 degrees and a retroversion angle of approximately 20 to 30 degrees relative to the epicondylar axis of the distal humerus. The harmonious interaction between the articular surface, the tuberosities, and the glenoid relies on this precise spatial orientation to maintain the critical force couples of the rotator cuff in both the coronal and transverse planes.

Osseous Architecture and Varus Collapse

Varus malunions, typically the sequelae of two-part surgical neck fractures, present a unique and devastating biomechanical challenge. In a varus deformity, the normal neck-shaft angle frequently collapses to less than 110 degrees, often settling between 98 and 107 degrees. This architectural distortion results in several critical biomechanical failures. First, it severely decreases the subacromial space; as the humeral head collapses into varus, the greater tuberosity is relatively elevated, bringing it into direct proximity with the coracoacromial arch and guaranteeing severe subacromial impingement during forward flexion and abduction. Second, the medialization of the greater tuberosity decreases the effective lever arm of the supraspinatus tendon, drastically reducing abduction strength and mechanical efficiency. Finally, the articular congruity is compromised, leading to eccentric loading of the glenoid and early-onset secondary osteoarthritis.

Tuberosity Migration and Rotator Cuff Kinematics

Malunions involving the greater or lesser tuberosities fundamentally alter the resting tension and dynamic function of the rotator cuff. Superior displacement of the greater tuberosity directly blocks abduction by creating a rigid bony impingement against the acromion, while posterior displacement alters external rotation mechanics and frequently leads to fixed internal rotation contractures. Conversely, a malunited lesser tuberosity can create a massive bony block anteriorly, impinging against the coracoid process (subcoracoid impingement) and severely restricting internal rotation. These osseous distortions are universally accompanied by profound soft tissue adaptations; the capsule becomes severely contracted, the coracohumeral ligament thickens, and the subscapularis often undergoes adaptive shortening, necessitating extensive, meticulous surgical releases to restore mobility.

Vascular Considerations in the Malunited State

The vascular anatomy of the proximal humerus is notoriously precarious, and its preservation is a central tenet of malunion surgery. The primary blood supply to the humeral head is derived from the anterior circumflex humeral artery via its anterolateral ascending branch (the arcuate artery of Laing), with significant collateral contributions from the posterior circumflex humeral artery supplying the posterior and inferior aspects of the head and greater tuberosity. In the setting of a malunion, this delicate vascular network is often distorted by scar tissue and aberrant bone formation. Surgical exposures, particularly those requiring tuberosity osteotomies, carry an exceptionally high risk of devascularizing the osseous fragments. Devascularization of the greater tuberosity during corrective osteotomy is a catastrophic complication that leads to nonunion, fragment migration, and massive failure of the rotator cuff mechanism, dictating that all soft tissue handling must strictly preserve the periosteal attachments.

Exhaustive Indications and Contraindications

The decision to proceed with operative intervention for a proximal humeral malunion must be predicated on a rigorous assessment of the patient's symptomatology, functional deficit, and physiological capacity to withstand a major reconstructive procedure and the ensuing months of arduous rehabilitation. The primary indications for surgical correction are severe, intractable pain and/or a profound loss of function that have proven entirely refractory to a comprehensive, well-documented trial of nonoperative management, which typically includes structured physical therapy, pharmacologic intervention, and judicious corticosteroid injections.

Nonoperative management is not synonymous with "no treatment" and remains the mandatory pathway for patients with severe medical comorbidities that preclude the safe administration of general anesthesia. It is also indicated for individuals with low functional demands and minimal pain who are able to maintain their activities of daily living with compensatory periscapular motion. Furthermore, patients who lack the cognitive or physical capacity to comply with the strict, phased postoperative rehabilitation protocols are absolute contraindications for complex joint-preserving osteotomies or arthroplasty, as noncompliance inevitably leads to construct failure, stiffness, or catastrophic instability.

The selection of the specific surgical procedure—ranging from isolated tuberoplasty to complex reverse total shoulder arthroplasty—is dictated by the specific pathoanatomy, the patient's age, the status of the articular cartilage, and the integrity of the rotator cuff. The following table provides an exhaustive breakdown of the indications and contraindications for the primary surgical modalities utilized in proximal humeral malunion reconstruction.

Pre-Operative Planning, Templating, and Patient Positioning

The complexity of proximal humeral malunion surgery demands an exhaustive preoperative planning phase. Standard radiography, while foundational, is entirely insufficient for complete spatial understanding of the deformity. A standard trauma series must be obtained, including a true anteroposterior (Grashey) view, a scapular Y view, and an axillary lateral view. The axillary view is particularly critical for assessing glenoid version, posterior subluxation, and the anterior-posterior relationship of the tuberosities. However, the distorted anatomy often obscures standard radiographic landmarks, making advanced imaging mandatory.

Advanced Imaging and Three-Dimensional Templating

A high-resolution computed tomography (CT) scan with three-dimensional (3D) surface-rendered reconstructions is the gold standard for preoperative evaluation. 3D CT allows the surgeon to precisely quantify the degree of varus/valgus collapse, the exact magnitude and direction of tuberosity migration, and the extent of secondary glenoid wear. Furthermore, modern digital templating software utilizing 3D CT data allows for virtual surgery. For corrective osteotomies, the surgeon can calculate the exact angle of the closing or opening wedge required to restore the 130-140 degree neck-shaft angle. For arthroplasty, 3D templating is invaluable for determining optimal glenoid component positioning, baseplate screw trajectories, and predicting the need for tuberosity osteotomy versus accepting slight malposition. Magnetic Resonance Imaging (MRI) is also highly recommended to evaluate the structural integrity, degree of retraction, and fatty infiltration (Goutallier classification) of the rotator cuff musculature, which directly dictates the choice between anatomic and reverse arthroplasty.

Patient Positioning and Operating Room Setup

Proper patient positioning is critical for surgical access and intraoperative imaging. The patient is typically placed in a modified "beach chair" position, with the head of the bed elevated to approximately 45 to 60 degrees. The patient must be positioned laterally enough on the operating table to allow full, unencumbered extension of the operative arm, which is essential for accessing the humeral shaft and delivering the humeral head during arthroplasty. A specialized shoulder positioner or a pneumatic arm holder is highly recommended to maintain the extremity in various degrees of rotation and elevation throughout the procedure.

The operating room must be configured to allow seamless access for the C-arm fluoroscopy unit. The C-arm should ideally be brought in from the contralateral side or from the head of the bed, ensuring that true AP and axillary views can be obtained dynamically without compromising the sterile field. Meticulous padding of all bony prominences, particularly the contralateral ulnar nerve and the bilateral common peroneal nerves, is mandatory given the anticipated prolonged operative time. Hypotensive anesthesia, if medically tolerated by the patient, can significantly improve visualization by reducing microvascular bleeding in the highly vascularized deltopectoral interval.

Step-by-Step Surgical Approach and Fixation Technique

Operative procedures for proximal humeral malunions fall into three broad categories: joint-preserving soft tissue reconstructions and osteotomies, arthroplasty, and salvage arthrodesis. The surgical approach and execution require meticulous soft tissue handling and rigid osseous fixation.

The Deltopectoral Approach and Soft Tissue Mobilization

Regardless of the definitive procedure, the vast majority of malunion reconstructions utilize an extended deltopectoral approach. The incision is made from the tip of the coracoid process extending distally toward the deltoid insertion. The deltopectoral interval is identified by the cephalic vein, which is typically retracted laterally with the deltoid to preserve its venous drainage, though medial retraction is acceptable if the vein is intimately tethered to the pectoralis major.

Upon entering the subdeltoid space, the surgeon immediately encounters profound bursal scarring and capsular contractures. A thorough subdeltoid, subacromial, and subcoracoid bursectomy is performed. The axillary nerve must be identified and protected; its course is often distorted by inferior capsular scarring or a malunited surgical neck. The nerve is palpated at the inferior border of the subscapularis (the "tug test") and protected throughout the procedure. For joint access, the subscapularis may be managed via a formal tenotomy, a peel from the lesser tuberosity, or a lesser tuberosity osteotomy. In the setting of a malunion, a lesser tuberosity osteotomy is often preferred as it allows for bone-to-bone healing and provides excellent exposure of the surgical neck and articular surface.

Joint-Preserving Corrective Osteotomy Techniques

For severe varus malunions of the surgical neck without significant articular degeneration, a closing wedge valgus osteotomy is the procedure of choice. Once the surgical neck is exposed, a laterally based closing wedge osteotomy is executed based on the preoperative 3D templating. Guide pins are placed to mark the superior and inferior cuts of the wedge. The osteotomy is performed using an oscillating saw, taking extreme care to protect the medial calcar hinge, the axillary nerve, and the posterior circumflex humeral vessels.

Once the bone wedge is excised, the arm is gently abducted to close the osteotomy site, correcting the neck-shaft angle back to approximately 130-140 degrees. Fixation must be exceptionally rigid due to the high biomechanical forces across the proximal humerus. A pre-contoured proximal humeral locking plate (e.g., PHILOS) is typically utilized. The plate is positioned lateral to the bicipital groove and distal to the greater tuberosity to avoid subacromial impingement. Multiple multi-planar locking screws are placed into the humeral head, with particular attention to placing robust calcar screws in the inferomedial quadrant of the head to resist varus collapse. Cortical screws are used in the humeral shaft.

If a greater tuberosity osteotomy is required for severe superior/posterior migration, it must be performed with surgical precision. The tuberosity is osteotomized using a sharp osteotome, preserving a sufficient shell of bone to accommodate heavy nonabsorbable sutures (#2 or #5 tape). Surgical Warning: The periosteal sleeve attaching the rotator cuff to the tuberosity fragment must not be violated, as this provides the sole remaining blood supply to the fragment. Once the humeral head or prosthesis is prepped, the tuberosity is reduced below the articular margin and secured using heavy transosseous sutures in a cerclage and figure-of-eight configuration.

Arthroplasty for Complex Multi-Part Malunions

When joint preservation is impossible due to advanced osteoarthritis, avascular necrosis, or a head-splitting malunion, arthroplasty is indicated. The execution of arthroplasty in this setting is fraught with challenges. The surgeon must decide whether to attempt a high-risk tuberosity osteotomy to reposition the rotator cuff or to accept a degree of malposition and adapt the prosthesis accordingly.

Historically, anatomic Total Shoulder Arthroplasty (aTSA) was utilized, but outcomes were frequently marred by tuberosity nonunion and persistent stiffness. Consequently, modern orthopedic consensus has heavily shifted toward Reverse Total Shoulder Arthroplasty (rTSA) for complex malunions, particularly in patients over 65 or those with compromised rotator cuffs. By medializing the center of rotation and distalizing the humerus, rTSA relies on the deltoid rather than the compromised rotator cuff. This allows the surgeon to frequently bypass the need for a formal tuberosity osteotomy; the greater tuberosity can often be simply contoured (tuberoplasty) with a high-speed burr to eliminate impingement, while the rTSA provides the necessary biomechanical advantage for functional elevation.

Complications, Incidence Rates, and Salvage Management

Surgeons must counsel patients extensively regarding the exceptionally high complication profile associated with proximal humeral malunion reconstruction. Even in the hands of master surgeons, the complication rate is significantly higher than that of primary arthroplasty or acute fracture fixation. The distorted anatomy, compromised vascularity, and requirement for extensive soft tissue releases create a perfect storm for postoperative morbidity.

The most devastating complication in joint-preserving surgery or anatomic arthroplasty is tuberosity nonunion or resorption. When a tuberosity is osteotomized, its endosteal blood supply is severed, leaving it entirely reliant on the precarious periosteal supply from the attached rotator cuff. If this fails, the tuberosity resorbs, leading to complete failure of the rotator cuff mechanism, severe superior migration of the humeral head, and pseudoparalysis. Furthermore, neurological injury is a constant threat; the altered anatomy places the axillary and musculocutaneous nerves at high risk during surgical exposure, aggressive retractor placement, and inferior capsular release.

The following table outlines the major complications, their estimated incidence rates based on landmark literature, and the appropriate salvage management strategies.

Phased Post-Operative Rehabilitation Protocols

Rehabilitation following the surgical correction of a proximal humeral malunion is an arduous, multi-month process that requires strict adherence to a phased protocol. The exact timeline is highly variable and depends entirely on the intraoperative stability of the osseous fixation, the quality of the soft tissues, and the specific procedure performed (osteotomy vs. rTSA). The surgeon must communicate specific "safe zones" of motion to the physical therapist based on intraoperative testing.

Phase I: Maximum Protection and Controlled Passive Motion (Weeks 0-6)

The primary goal of Phase I is to protect the osteotomy or tuberosity repair while preventing the rapid onset of adhesive capsulitis. The shoulder is strictly immobilized in a sling or a specialized abduction orthosis (particularly if a rotator cuff repair or tuberosity osteotomy was performed). Immediate initiation of elbow, wrist, and hand active range of motion is mandatory to prevent distal edema and stiffness.

Passive range of motion (PROM) of the glenohumeral joint is initiated early, typically within the first 3 to 7 days postoperatively, but strictly within the safe zones determined intraoperatively. For example, external rotation is often strictly limited to 0 or 30 degrees to protect a subscapularis repair or lesser tuberosity osteotomy. Forward elevation in the scapular plane is performed passively by the therapist. Absolutely no active elevation or active rotation is permitted during this phase, as the dynamic pull of the musculature can easily displace a healing osteotomy.

Phase II: Active-Assisted and Active Kinematic Restoration (Weeks 6-12)

Progression to Phase II is strictly contingent upon radiographic confirmation of early osseous healing (callus formation or obscuration of osteotomy lines). Once cleared, the patient transitions from PROM to active-assisted range of motion (AAROM). This involves the use of overhead pulleys, wand exercises, and wall-walks to begin engaging the musculature while still providing mechanical support to the weight of the arm.

Around week 8 to 10, gradual introduction of active range of motion (AROM) in all planes is initiated. The focus is on re-establishing proper scapulothoracic kinematics, as patients with chronic malunions develop profound compensatory shoulder hiking. Gentle, sub-maximal isometric strengthening of the deltoid and rotator cuff is introduced. Hydrotherapy can be highly beneficial during this phase to allow active motion in a buoyant, gravity-reduced environment.

Phase III: Progressive Resistance and Functional Return (Months 3-6+)

Phase III focuses on progressive resistive exercises (PREs) to rebuild the severely atrophied musculature. Elastic resistance bands and light isotonic weights are utilized to strengthen the rotator cuff, deltoid, and critical periscapular stabilizers (serratus anterior, rhomboids, trapezius). Advanced proprioceptive training is incorporated.

Patients must be counseled that maximal medical improvement is rarely achieved before 12 to 18 months postoperatively. Return to heavy manual labor, overhead sports, or high-impact activities is generally restricted until at least 6 to 9 months postoperatively, and is entirely contingent upon complete radiographic union, absence of pain, and restoration of near-symmetric functional strength. In many cases of complex reconstruction, permanent lifting restrictions may be recommended to ensure the longevity of the hardware or prosthesis.

Summary of Landmark Literature and Clinical Guidelines

The evolution of surgical strategies for proximal humeral malunions is deeply rooted in several landmark clinical studies that have shaped modern orthopedic guidelines. A comprehensive understanding of this literature is essential for evidence-based decision-making.

The critical importance of surgical timing was definitively established by Beredjiklian et al. in their seminal analysis of malunion reconstructions. Their data unequivocally demonstrated that intervention within the first 12 months of injury yields a satisfactory outcome in 84% of cases, whereas intervention delayed beyond one year plummets the satisfactory outcome rate to 55%. This established the modern clinical guideline that watchful waiting in the face of a symptomatic, developing malunion is detrimental, and early reconstructive intervention is paramount to preserving joint kinematics and preventing irreversible soft tissue contracture.

Regarding joint-preserving techniques, Benegas et al. provided the foundational framework for the closing wedge valgus osteotomy in the treatment of severe surgical neck varus malunions. Their work highlighted that restoring the 130-140 degree neck-shaft angle not only relieves subacromial impingement but dramatically improves the mechanical advantage of the supraspinatus, provided the articular cartilage remains viable. For milder deformities, the work of Siegel and Dines, later expanded upon by Martinez et al. using all-arthroscopic techniques, validated that acromioplasty combined with aggressive tuberoplasty (burring of the prominent greater tuberosity without osteotomy) is a highly effective, lower-risk alternative for patients with intact articular surfaces and minimal (<1.5 cm) tuberosity displacement.

The role of arthroplasty in malunion management has undergone a massive paradigm shift, largely driven by the sobering long-term data regarding anatomic Total Shoulder Arthroplasty (aTSA). Antuna et al. evaluated the long-term results of aTSA for humeral malunions, reporting that while 75% to 85% of patients achieved significant pain relief, functional outcomes were severely limited by stiffness, with only 50% achieving satisfactory Neer functional scores. Furthermore, studies by Boileau and Mansat highlighted the catastrophic failure rates of tuberosity osteotomies performed during aTSA, with nonunion/resorption rates reaching 41%.

These high failure rates led to the modern clinical guideline, initially suggested by Neer himself, that accepting slight malposition of the tuberosities is often preferable to performing a high-risk osteotomy. Today, this data has driven the widespread adoption of Reverse Total Shoulder Arthroplasty (rTSA) for complex malunions in older patients. By medializing the center of rotation, rTSA negates the need for a functioning rotator cuff, allowing the surgeon to bypass the high-risk tuberosity osteotomy entirely, relying instead on the deltoid to restore functional elevation and providing a much more predictable outcome in this highly challenging patient population.