INTRODUCTION TO PROXIMAL HUMERAL MALUNIONS
The treatment of proximal humeral malunions represents one of the most technically demanding challenges in reconstructive shoulder surgery. Distorted osseous anatomy, profound soft tissue contractures, altered glenohumeral biomechanics, and compromised vascularity combine to make surgical intervention highly complex. The primary goals of treatment are the alleviation of severe pain, the restoration of functional range of motion, and the re-establishment of glenohumeral stability.
Decision-making must be highly individualized, taking into account the patient's physiological age, functional demands, the specific pathoanatomy of the malunion (e.g., varus collapse, tuberosity migration), the status of the rotator cuff, and the integrity of the articular cartilage.
NONOPERATIVE MANAGEMENT
Nonoperative management is generally reserved for a highly specific subset of patients. It may be indicated for individuals with low functional demands and minimal pain who are able to maintain independence with limited use of the affected upper extremity. Furthermore, conservative care is the mandatory pathway for patients with severe medical comorbidities that preclude safe administration of anesthesia or those who lack the cognitive or physical capacity to comply with rigorous postoperative rehabilitation protocols.
When nonoperative management is selected, the regimen typically consists of:
* Physical Therapy: Focused on maximizing compensatory periscapular motion and maintaining whatever glenohumeral mobility remains.
* Pharmacologic Intervention: Judicious use of nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesics.
* Corticosteroid Injections: Subacromial or intra-articular injections to manage localized inflammatory pain and impingement symptoms.
Clinical Pearl: Nonoperative management is not synonymous with "no treatment." A structured, supervised physical therapy program focusing on scapulothoracic kinematics can significantly improve the functional envelope of a patient with a stiff, malunited glenohumeral joint.
INDICATIONS AND TIMING FOR SURGICAL INTERVENTION
The primary indications for surgical correction of proximal humeral malunions are severe, intractable pain and/or profound loss of function that have proven refractory to a comprehensive trial of nonoperative management. The patient must be deemed an appropriate operative candidate based on overall health, bone quality, and functional expectations.
The Critical Role of Surgical Timing
The chronicity of the malunion plays a pivotal role in determining the ultimate functional outcome. Beredjiklian et al. demonstrated that a delay in operative treatment has a profound negative effect on surgical success. In their landmark analysis, 84% (16 of 19) of patients treated less than one year after the initial injury achieved satisfactory outcomes. Conversely, only 55% (11 of 20) of patients treated more than one year post-injury achieved similar results.
This discrepancy is largely attributed to the progressive, irreversible nature of soft tissue contractures, capsular scarring, and secondary degenerative changes within the glenohumeral joint over time. Therefore, early recognition of an impending or established malunion and prompt surgical intervention are paramount.
BIOMECHANICS AND PATHOANATOMY
Understanding the altered biomechanics of a proximal humeral malunion is essential for preoperative planning.
Varus Malunions of the Surgical Neck
Varus malunions (typically sequelae of two-part surgical neck fractures) present a unique biomechanical challenge. The normal humeral neck-shaft angle ranges from 130 to 140 degrees. In a varus deformity, this angle frequently collapses to less than 110 degrees (often ranging from 98 to 107 degrees).
This architectural distortion results in several critical biomechanical failures:
1. Decreased Subacromial Space: As the humeral head collapses into varus, the greater tuberosity is elevated relative to the articular surface, bringing it into closer proximity to the coracoacromial arch. This guarantees severe subacromial impingement during forward flexion and abduction.
2. Altered Supraspinatus Lever Arm: The medialization of the greater tuberosity decreases the effective lever arm of the supraspinatus tendon, drastically reducing abduction strength and efficiency.
3. Articular Incongruity: The sliding surface of the humeral head against the glenoid is altered, leading to abnormal wear patterns and early-onset secondary osteoarthritis.
Tuberosity Malunions
Superior or posterior displacement of the greater tuberosity alters the tension of the rotator cuff. Superior migration directly blocks abduction by impinging against the acromion, while posterior displacement alters external rotation mechanics and can lead to fixed internal rotation contractures.
SURGICAL OPTIONS AND TECHNIQUES
Operative procedures for proximal humeral malunions fall into three broad categories: joint-preserving osteotomies and soft tissue reconstructions, arthroplasty, and salvage arthrodesis.
1. Joint-Preserving Procedures
Joint preservation is indicated when the blood supply to the humeral head is maintained, the articular cartilage is preserved, and the patient is physiologically young or highly active.
Acromioplasty and Tuberoplasty
If pain and impingement are the primary complaints and loss of motion is minimal, excision of bony prominences and lysis of adhesions may suffice. Siegel and Dines recommended this approach for mild deformities.
For greater tuberosity fractures with minimal displacement (1.0 to 1.5 cm), Beredjiklian et al. stated that acromioplasty alone may be indicated. Martinez et al. expanded on this, reporting successful outcomes using an all-arthroscopic approach consisting of:
* Arthroscopic acromioplasty.
* Detachment of the rotator cuff.
* Tuberoplasty (burring down the prominent greater tuberosity).
* Arthroscopic repair of the rotator cuff.
Arthroscopy is also invaluable for assessing intra-articular abnormalities, treating capsular contractures, and managing subcoracoid impingement (e.g., arthroscopic debridement of a malunited lesser tuberosity causing a bony block to internal rotation).
Tuberosity Osteotomy and Reduction
If the greater tuberosity is displaced more than 1.5 cm, simple tuberoplasty is insufficient; the tuberosity must be osteotomized and repositioned to restore the rotator cuff lever arm.
Surgical Technique:
1. Positioning: The patient is placed in a modified "beach chair" position.
2. Approach: An anterosuperior or deltopectoral approach is utilized.
3. Osteotomy: The malunited tuberosity is carefully osteotomized.
4. Fixation: It is critical to maintain a tuberosity fragment large enough to accommodate reattachment. Fixation is achieved using heavy, nonabsorbable sutures passed through transosseous tunnels.
Surgical Warning: Devascularization of the greater tuberosity during osteotomy is a catastrophic complication leading to nonunion, migration, and resorption. Meticulous soft tissue handling, preserving the periosteal attachments of the rotator cuff to the bone fragment, is mandatory.
Corrective Valgus Osteotomy for Varus Malunions
For severe varus malunions of the surgical neck without significant arthritis, a closing wedge valgus osteotomy is the procedure of choice, as described by Benegas et al.
Contraindications: Massive rotator cuff tears, significant arthritic changes, avascular necrosis (AVN), multiple angular deformities, active infection, and concurrent nerve injury.
Surgical Technique (Step-by-Step):
1. Approach: A standard deltopectoral approach is utilized.
2. Exposure: The subscapularis is either tenotomized or a lesser tuberosity osteotomy is performed to expose the surgical neck.
3. Osteotomy: A laterally based closing wedge osteotomy is planned based on preoperative templating. The wedge is excised from the surgical neck to correct the neck-shaft angle back to approximately 130-140 degrees.
4. Fixation: The osteotomy is reduced and stabilized using a robust construct, typically a proximal humeral locking plate or a T-shaped plate with 4.5-mm screws.
5. Soft Tissue Balancing: Concomitant soft tissue contractures must be released, including capsular release from the humeral neck or glenoid rim.
2. Shoulder Arthroplasty
Arthroplasty is the treatment of choice for three-part and four-part malunions, head-splitting malunions, and cases complicated by severe articular damage, avascular necrosis, or secondary osteoarthritis.
The choice between hemiarthroplasty, anatomic total shoulder arthroplasty (aTSA), and reverse total shoulder arthroplasty (rTSA) depends heavily on the integrity of the rotator cuff, the condition of the glenoid, and the patient's age.
Outcomes and Challenges of Arthroplasty
Prosthetic replacement for malunions yields less predictable results than arthroplasty performed for acute fractures or primary glenohumeral osteoarthritis. The distorted bony anatomy and profound soft tissue stiffness make the procedure exceptionally demanding.
Antuna et al. evaluated long-term results of shoulder arthroplasties for humeral malunions. While significant pain relief was achieved in the majority of patients (75% to 85%), functional outcomes were frequently limited by long-standing stiffness. Overall, only 50% achieved excellent or satisfactory results by Neer’s criteria.
Pitfall: Tuberosity osteotomy during arthroplasty for malunion carries an exceptionally high complication rate. In studies by Mansat, Boileau, and Antuna, patients requiring greater tuberosity osteotomies during arthroplasty experienced nonunion, malunion, or resorption rates as high as 41%. None of the patients with tuberosity osteotomies in Boileau's series achieved greater than 90 degrees of active elevation.
Because of this high failure rate, Neer and subsequent authors have suggested that accepting slight malposition (varus or valgus) of the humeral component is often preferable to performing a high-risk tuberosity osteotomy, provided that stability and impingement-free motion can be achieved.
The Role of Reverse Total Shoulder Arthroplasty (rTSA)
While historically the role of rTSA in malunions was considered unclear, modern orthopedic consensus increasingly favors rTSA for older patients with proximal humeral malunions, particularly when there is concurrent rotator cuff dysfunction, severe tuberosity malposition, or when a tuberosity osteotomy is deemed necessary but carries a high risk of nonunion. By medializing the center of rotation and distalizing the humerus, rTSA relies on the deltoid rather than the compromised rotator cuff, often providing superior functional elevation compared to anatomic arthroplasty in this challenging cohort.
3. Arthrodesis
Glenohumeral arthrodesis is strictly a salvage procedure. It is indicated rarely, primarily reserved for patients with a severe, irreversible neurological deficit (e.g., complete brachial plexus palsy) or a history of recalcitrant deep periarticular infection where arthroplasty is absolutely contraindicated.
POSTOPERATIVE REHABILITATION PROTOCOLS
Rehabilitation following surgical correction of a proximal humeral malunion is arduous and requires strict adherence to a phased protocol. The exact timeline depends on the stability of the fixation and the quality of the soft tissues.
Phase I: Protection and Passive Motion (Weeks 0-6)
* The shoulder is immobilized in a sling or abduction orthosis.
* Immediate initiation of elbow, wrist, and hand range of motion.
* Passive range of motion (PROM) of the shoulder is initiated early (within the first week) to prevent adhesive capsulitis, but strictly within safe zones determined intraoperatively to protect osteotomy or tuberosity repairs.
* No active elevation or rotation.
Phase II: Active-Assisted and Active Motion (Weeks 6-12)
* Radiographic confirmation of early osseous healing is required before progressing.
* Transition from PROM to active-assisted range of motion (AAROM), utilizing pulleys and wand exercises.
* Gradual introduction of active range of motion (AROM) in all planes.
* Gentle isometric strengthening of the deltoid and rotator cuff.
Phase III: Strengthening and Functional Return (Months 3-6+)
* Progressive resistive exercises (PREs) using elastic bands and light weights.
* Focus on periscapular stabilization and advanced rotator cuff strengthening.
* Return to heavy labor or high-impact activities is generally restricted until 6 to 9 months postoperatively, contingent upon complete radiographic union and functional recovery.
COMPLICATIONS
Surgeons must counsel patients extensively regarding the high complication profile associated with malunion reconstruction:
1. Tuberosity Nonunion/Resorption: As noted, devascularization of the tuberosities during osteotomy leads to catastrophic failure of the rotator cuff mechanism.
2. Persistent Stiffness: Due to chronic capsular contracture, many patients will not regain full normal range of motion, even with a technically perfect surgery.
3. Neurological Injury: The altered anatomy places the axillary and musculocutaneous nerves at high risk during surgical exposure and soft tissue release. Antuna et al. reported partial brachial plexus palsies in their series.
4. Hardware Failure and Impingement: In joint-preserving osteotomies, prominent hardware may cause secondary impingement, necessitating a second operation for hardware removal once union is achieved.
