Posterior Radius: Expert Tips for Brevis and the Extensor Side

As academic orthopedic surgeons and educators, our commitment extends beyond technical mastery to the nuanced understanding of surgical principles, anatomical intricacies, and evidence-based practice. The posterior approach to the radius, while fundamental, requires meticulous attention to detail, particularly concerning the posterior interosseous nerve (PIN). This comprehensive review aims to distill expert tips and current insights for residents, fellows, and practicing surgeons, focusing on precision, safety, and optimal patient outcomes for procedures involving the extensor side of the radial shaft.

Introduction and Epidemiology

The posterior approach to the radius offers unparalleled access to the dorsal and dorsolateral aspects of the radial diaphysis and proximal metaphysis. Its primary utility lies in addressing pathologies on the "tensile side" of the bone, a critical biomechanical consideration for robust internal fixation. Historically, approaches to the forearm have evolved to prioritize internervous planes, minimize muscle damage, and safeguard vital neurovascular structures. The posterior approach, specifically designed to navigate the extensor compartment, exemplifies this evolution.

Radial shaft fractures constitute a significant portion of forearm trauma, often occurring in bimodal age distributions, with high-energy mechanisms in younger individuals and low-energy falls in the osteoporotic elderly. While the preferred approach for many diaphyseal fractures is volar due to the broader anatomical window and reduced risk to major nerves, the posterior approach remains indispensable for specific indications. These include fractures with extensive dorsal comminution, nonunions where previous volar plating has failed, or in the presence of existing nerve pathology requiring decompression. Furthermore, its role extends beyond trauma to include reconstructive procedures like osteotomies, tumor excisions, and debridement of chronic osteomyelitis. The inherent risk of posterior interosseous nerve injury necessitates a profound anatomical understanding and a disciplined surgical technique, transforming what could be a straightforward exposure into a challenging exercise in nerve protection.

Surgical Anatomy and Biomechanics

A thorough understanding of the regional anatomy is paramount for safe and effective utilization of the posterior approach to the radius. Precision in identifying and navigating relevant structures safeguards against iatrogenic injury and ensures adequate exposure for complex procedures.

Osteology of the Radius and Ulna

The radius is the larger of the two forearm bones proximally and distally, articulating with the humerus at the elbow and the carpus at the wrist. Its shaft is triangular in cross-section proximally, becoming more oval distally. The posterior surface, particularly in the proximal and mid-diaphysis, is relatively flat, making it conducive for plate application. The interosseous border provides attachment for the interosseous membrane, which transmits loads between the radius and ulna, stabilizing the forearm unit. The radial head articulates with the capitellum of the humerus and the radial notch of the ulna, facilitating pronation and supination.

Musculature of the Posterior Forearm

The muscles of the posterior forearm are organized into superficial and deep compartments, all primarily responsible for wrist and finger extension, as well as forearm supination. The key to the posterior approach involves understanding the internervous planes within these compartments.

• Superficial Extensor Muscles:

  • Brachioradialis: Originates from the lateral supracondylar ridge of the humerus, inserts onto the radial styloid. Innervated by the radial nerve (proximal to the deep branch). It forms the lateral boundary of the approach.
  • Extensor Carpi Radialis Longus (ECRL) and Brevis (ECRB): Originate from the lateral supracondylar ridge and lateral epicondyle, respectively, inserting into the bases of the second and third metacarpals. Innervated by the radial nerve (proximal). These muscles lie deep to the brachioradialis and lateral to the extensor digitorum communis.
  • Extensor Digitorum Communis (EDC): Originates from the lateral epicondyle, divides into four tendons for the medial four digits. Innervated by the PIN.
  • Extensor Digiti Minimi (EDM): Originates from the lateral epicondyle, inserts into the fifth digit extensor expansion. Innervated by the PIN.
  • Extensor Carpi Ulnaris (ECU): Originates from the lateral epicondyle and posterior ulna, inserts into the base of the fifth metacarpal. Innervated by the PIN.
  • These muscles are retracted medially and laterally to expose the deeper structures and the radial shaft.

• Deep Extensor Muscles:

  • Supinator: A broad, two-headed muscle that winds around the proximal radius. Its superficial head originates from the lateral epicondyle and radial collateral ligament, while its deep head originates from the supinator crest of the ulna. Both insert onto the anterior, lateral, and posterior surfaces of the proximal radius. It is critically important as the posterior interosseous nerve passes through its two heads. Innervated by the PIN.
  • Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB), Extensor Pollicis Longus (EPL), Extensor Indicis Proprius (EIP): These "outcropping" muscles of the thumb and index finger lie distal to the supinator and are all innervated by the PIN. They are typically retracted or separated as needed for distal exposures.
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Neurovascular Structures

• Radial Nerve:
  • The radial nerve descends through the posterior compartment of the arm. At the level of the lateral epicondyle, it divides into its superficial and deep branches.
  • Superficial Radial Nerve: Primarily sensory, it runs deep to the brachioradialis and then subcutaneously in the distal forearm. It provides sensation to the dorsum of the hand. It is generally not in the field of the posterior approach to the radial shaft but can be at risk with more distal extensions or lateral incisions.
  • Deep Branch of the Radial Nerve (Posterior Interosseous Nerve - PIN): This is the motor branch of the radial nerve to the extensor compartment. It pierces the supinator muscle, passing through the Arcade of Frohse, a fibrous arch at the proximal extent of the superficial head of the supinator. The PIN supplies the supinator, EDC, EDM, ECU, APL, EPB, EPL, and EIP. Its vulnerability within the supinator muscle is the cardinal risk of the posterior radial approach.
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• Vascular Structures: The posterior interosseous artery (a branch of the common interosseous artery) and its accompanying veins run distally in the intermuscular septum between the superficial and deep extensor layers. While generally not a major concern, awareness of these vessels helps minimize bleeding and maintain a clear field.

Internervous Plane

The classic internervous plane for the posterior approach to the radial shaft is between the brachioradialis (innervated by the radial nerve proximal to its deep branch) and the extensor carpi radialis brevis/longus (also innervated by the radial nerve proximal to its deep branch). Alternatively, a plane can be developed between the ECRB and the EDC/EDM/ECU complex, all of which are innervated by the PIN. The critical structure to expose and protect is the PIN as it enters the supinator muscle. The ideal approach identifies the deep branch of the radial nerve entering the supinator, then carefully incises the supinator longitudinally along the line of its fibers, parallel to the nerve, to expose the bone while keeping the PIN under direct visualization. This ensures the muscle is split, not denervated, and the PIN is protected.

Biomechanics of Dorsal Plating

For diaphyseal fractures, especially those in the mid and proximal radius, biomechanical studies highlight the advantages of dorsal plate placement. The dorsal aspect of the radial shaft is considered the "tensile side" during typical forearm loading (e.g., pronation with axial compression). Placing a plate on the tensile side allows it to act as a tension band, neutralizing tensile forces and converting compressive forces, thereby providing optimal stability for fracture healing. While volar plating is common, a dorsal plate can offer superior mechanical advantages in specific fracture patterns, particularly those with significant comminution of the dorsal cortex where a volar plate might encounter issues with pullout strength or require extensive bone grafting.

Indications and Contraindications

The decision to employ the posterior approach to the radius is based on a careful assessment of the pathology, fracture characteristics, patient factors, and the biomechanical requirements for stable fixation.

Operative Indications

The posterior approach provides versatile access for a variety of conditions:

• Open Reduction and Internal Fixation (ORIF) of Radial Fractures:
  • Proximal and Mid-Shaft Fractures: Especially those with significant dorsal comminution or instability that would benefit from a dorsal tension band plate.
  • Monteggia Equivalent Fractures: Where radial head dislocation is associated with a radial shaft fracture, and dorsal plating of the radius aids in reduction and stability of the proximal radio-ulnar joint.
  • Specific Fracture Morphology: Highly comminuted fractures or segmental defects of the dorsal cortex where a volar approach might struggle to achieve stable fixation without bone grafting.
• Treatment of Delayed Union or Nonunion of Radial Fractures:
  • Revision surgery following failed initial fixation, particularly if the initial plate was volar and dorsal comminution was not adequately addressed.
  • When the nonunion gap requires direct visualization, debridement, and bone grafting, and the posterior aspect provides better access.
• Posterior Interosseous Nerve (PIN) Pathology:
  • Decompression of the PIN: For nerve paralysis secondary to compression (e.g., within the Arcade of Frohse or other fibrous bands) or resistant cases of lateral epicondylitis (tennis elbow) where PIN entrapment is suspected as a contributing factor.
  • Nerve Exploration and Repair: In cases of documented PIN injury or transection.
• Radial Osteotomy:
  • Corrective osteotomies for malunion (e.g., rotational, angular deformity) of the radial shaft, allowing precise bone cuts and stable fixation.
  • Shortening osteotomies for conditions like ulnar impaction syndrome (though often done distally via other approaches).
• Treatment of Chronic Osteomyelitis of the Radius:
  • Debridement of infected bone, removal of sequestra, and management of bone defects. The posterior approach allows direct access to the bone, facilitating thorough débridement and antibiotic bead placement.
• Biopsy and Treatment of Bone Tumors:
  • Excisional biopsy or resection of benign or malignant bone tumors involving the radial shaft, allowing for wide margins and reconstruction.

Contraindications

• Absolute Contraindications:
  • Active Infection in the Surgical Field (Uncontrolled): While the approach can be used for chronic osteomyelitis, an uncontrolled active soft tissue infection in the immediate surgical field would contraindicate hardware placement without prior infection control.
  • Severe Soft Tissue Compromise: Extensive scarring, burns, or open wounds on the dorsal forearm may preclude a safe posterior approach.
• Relative Contraindications:
  • Fractures of the Distal Radius: These are typically managed via a volar or dorsal approach specific to the wrist, as the posterior approach to the shaft is often too proximal for optimal access.
  • Isolated Volar Comminution: If the primary instability is on the volar side of the radius, a volar approach might offer better direct reduction and compression.
  • Patient Comorbidities: Severe medical comorbidities that preclude general anesthesia or prolonged surgery.
  • Prior Surgery with Significant Scarring: Can obliterate planes and increase the risk of nerve injury.

Operative versus Non-Operative Indications

The choice between operative and non-operative management for radial pathologies is critical. The posterior approach is strictly an operative strategy, indicated when non-operative treatment is unsuitable or has failed.

Pre Operative Planning and Patient Positioning

Meticulous preoperative planning is essential for optimizing surgical efficiency, minimizing complications, and achieving superior clinical outcomes.

Clinical Assessment

A comprehensive clinical evaluation includes:
* Neurological Examination: Document baseline motor function of all extensor compartment muscles (PIN-innervated) and sensory integrity of the superficial radial nerve. This provides a crucial baseline for post-operative comparison.
* Vascular Assessment: Palpation of radial and ulnar pulses, capillary refill.
* Soft Tissue Envelope: Assess for open wounds, abrasions, blistering, or significant swelling, which may delay surgery or alter the approach.

Imaging Modalities

• Standard Radiographs: Anteroposterior and lateral views of the forearm, including the elbow and wrist, are essential for characterizing fracture patterns, displacement, and comminution. Traction views can provide additional information.
• Computed Tomography (CT) Scan: Indicated for complex fracture patterns, malunions requiring osteotomy, or tumor evaluation. 3D reconstructions are invaluable for understanding fracture morphology and planning corrective osteotomies.
• Magnetic Resonance Imaging (MRI): Useful for evaluating soft tissue lesions (tumors), assessing nerve compression (PIN entrapment), or delineating infection extent in osteomyelitis.
• Electromyography (EMG) and Nerve Conduction Studies (NCS): Crucial for confirming PIN neuropathy and localizing the compression site in nerve decompression cases.

Surgical Environment and Equipment

• Tourniquet: Essential for a bloodless field, which significantly aids in nerve identification and protection.
• Fluoroscopy: Intraoperative image intensification is invaluable for confirming reduction, plate position, and screw length.
• Instrumentation: Standard orthopedic trauma sets, small fragment sets, nerve hooks, fine dissection instruments, specialized retractors (e.g., self-retaining army-navy or Senn retractors).
• Implants: Plates (e.g., 3.5 mm locking compression plates, LC-DCPs) and screws appropriate for the radial shaft, bone graft materials (autograft/allograft) if required.

Anesthesia

Regional anesthesia (e.g., axillary block) alone or in combination with general anesthesia is often preferred. Regional blocks provide excellent pain control both intraoperatively and postoperatively, facilitating early mobilization and rehabilitation.

Patient Positioning

The patient can be positioned in one of two ways, both designed to expose the extensor compartment effectively:

1. Supine with Arm on an Arm Board:
   • The patient is placed supine on the operating table.
   • The operative arm is positioned on a radiolucent arm board, allowing full access around the limb.
   • The forearm is maximally pronated to bring the dorsal aspect of the radius into the operative field. This position is particularly useful for isolated radial shaft pathology.
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2. Supine with Arm Across the Chest:
   • The patient is placed supine.
   • The operative arm is adducted and placed across the patient's chest. This position pronates the forearm and exposes the dorsal aspect.
   • This position offers the advantage of easier access to the ulna through a separate incision if a combined approach to both forearm bones is necessary (e.g., in a complex forearm fracture involving both bones).
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Exsanguination and Tourniquet Application

• Prior to tourniquet inflation, the limb is exsanguinated by either elevating the arm for 3 to 5 minutes or by applying a soft rubber bandage (Esmarch exsanguinator) from distal to proximal.
• A pneumatic tourniquet is then inflated to a pressure typically 100-150 mmHg above systolic blood pressure, or to a safe, predetermined level. A bloodless field is critical for precise identification and protection of the PIN.

Draping and Sterile Field

The entire arm, including the shoulder, elbow, and hand, should be draped to allow for full range of motion of the elbow and wrist, which may be required for reduction maneuvers or assessing nerve function. Prophylactic intravenous antibiotics should be administered pre-incision according to institutional protocols.

Detailed Surgical Approach and Technique

The posterior approach to the radius demands a methodical, layer-by-layer dissection with constant vigilance for the posterior interosseous nerve.

Landmarks and Incision

• Landmarks: Palpate the lateral epicondyle of the humerus, the radial head, and the dorsal aspect of the radial shaft. The posterior border of the brachioradialis muscle can be palpated, delineating the lateral extent of the extensor compartment.
• Incision: A straight longitudinal incision is made on the dorsal aspect of the forearm, centered over the palpable radial shaft. The incision typically extends from the lateral epicondyle proximally to the desired distal extent, allowing adequate exposure. For proximal radial shaft fractures or PIN decompression, the incision will start near the lateral epicondyle. For mid-shaft fractures, it will be centered over the fracture site.
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Superficial Dissection

1. Skin and Subcutaneous Tissue: Incise the skin and subcutaneous fat. The superficial radial nerve, a purely sensory nerve, runs subcutaneously in the distal forearm. While generally not in the primary field for a proximal or mid-shaft approach, it is important to be aware of its course and protect it during distal extensions of the incision.
2. Deep Fascia: The deep forearm fascia is incised longitudinally. This exposes the extensor compartment muscles.
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Identifying the Internervous Plane and Nerve Isolation

1. Identify Brachioradialis: The brachioradialis muscle is a reliable landmark, forming the lateral boundary of the superficial extensor muscles. It is typically retracted radially (laterally).
2. Identify ECRL/ECRB and EDC: Medial to the brachioradialis, identify the extensor carpi radialis longus and brevis muscles. Medial to these is the extensor digitorum communis.

3. The Critical Internervous Plane: The posterior approach can utilize two main internervous planes, both leading to the PIN's location:

   • Between Brachioradialis and ECRL/ECRB: Retracting the brachioradialis laterally and the ECRL/ECRB medially can expose deeper structures. However, this may not be the most direct route to the PIN.
   • Between ECRB and EDC: A more commonly utilized and direct approach involves identifying the interval between the Extensor Carpi Radialis Brevis (retracted laterally) and the Extensor Digitorum Communis (retracted medially). This plane provides direct access to the supinator muscle, which overlies the proximal radius.

4. Locate the Deep Branch of the Radial Nerve (PIN): This is the most crucial step. The deep branch of the radial nerve can be found approximately 3-4 cm distal to the lateral epicondyle, where it enters the substance of the supinator muscle.

   • Carefully dissect through the muscle fibers of the supinator, identifying the distinct fibrous arch of the Arcade of Frohse (the proximal border of the superficial head of the supinator). The nerve typically passes under this arcade.
   • The nerve should be identified, carefully mobilized, and protected. Use a nerve hook or fine instrument to gently elevate it from the supinator.
   • Expert Tip: Maintain constant direct visualization of the PIN throughout the procedure. Use moistened vessel loops or thin retractors for gentle retraction, ensuring no undue tension or compression on the nerve.
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5. Splitting the Supinator: Once the PIN is identified and protected, the supinator muscle can be incised longitudinally, parallel to its fibers and the course of the nerve. This allows exposure of the radial shaft beneath, while preserving the muscle's integrity and innervation. This subperiosteal dissection of the radial shaft then proceeds, minimizing muscle stripping to preserve vascularity.

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Exposure of the Radius and Fracture Reduction

1. Subperiosteal Exposure: With the PIN safely retracted, subperiosteal dissection of the radial shaft can proceed. Extend the dissection proximally and distally as needed to fully expose the fracture site or area of pathology. Minimize periosteal stripping where possible to preserve the biological environment for healing.
2. Fracture Reduction:
   • Direct visualization of the fracture fragments allows for accurate anatomical reduction.
   • Use reduction clamps, pointed reduction forceps, bone hooks, or K-wires for temporary fixation.
   • Restore length, alignment (angular and rotational), and articular congruity if applicable (proximal or distal extensions). For diaphyseal fractures, rotational alignment is critical and can be assessed by correlating with the distal ulna or by comparing to the contralateral limb's relative thumb/index finger position.
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Internal Fixation

1. Plate Selection: For dorsal plating of the radius, 3.5 mm locking compression plates (LCPs) or dynamic compression plates (DCPs) are commonly used. Plates should be sufficiently long to provide adequate working length and hold in the bone proximal and distal to the fracture.
2. Plate Contouring: The plate should be carefully contoured to match the natural dorsal curvature of the radial shaft. Proper contouring helps in achieving anatomical reduction and prevents plate prominence, which can cause soft tissue irritation.
3. Screw Insertion:
   • Apply the plate to the dorsal aspect of the radius.
   • For LCPs, locking screws provide fixed-angle stability, useful in comminuted or osteoporotic bone.
   • For DCPs, cortical screws provide compression across simple fracture patterns. Lag screws can be used through the plate or separately to achieve interfragmentary compression.
   • Ensure adequate screw purchase (at least 6 cortices proximal and distal to the fracture in simple patterns, more for comminuted fractures) and bicortical screw placement for optimal stability, while avoiding distraction.
   • Confirm final reduction and implant position with fluoroscopy.
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Posterior Interosseous Nerve Decompression (If Indicated)

If the primary indication is PIN decompression, following isolation of the nerve, formal release of the Arcade of Frohse and any other constricting fibrous bands (e.g., leash of Henry, distal border of supinator) is performed. The nerve should be able to move freely without impingement.

Closure

1. Irrigation: Thoroughly irrigate the wound with sterile saline.
2. Hemostasis: Achieve meticulous hemostasis.
3. Muscle and Fascia Repair: The incised supinator muscle is loosely reapproximated with absorbable sutures to cover the plate. The extensor muscle bellies (EDC, ECRB) are allowed to fall back into their anatomical positions. The deep fascia is then closed with absorbable sutures.
4. Subcutaneous and Skin Closure: Close the subcutaneous layer and skin in a standard fashion using preferred suture material.
5. Dressing and Splint: Apply a sterile dressing. A well-padded sugar tong splint or posterior splint is applied, immobilizing the elbow at 90 degrees of flexion and the wrist in a neutral position, for initial protection and comfort.
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Complications and Management

Despite meticulous surgical technique, complications can arise following the posterior approach to the radius. Surgeons must be aware of potential issues and have strategies for their management.

Nerve Injury

• Posterior Interosseous Nerve (PIN) Palsy: This is the most significant and feared complication, occurring in approximately 0.5% to 5% of cases.
  • Mechanism: Direct trauma during dissection, excessive traction during retraction, compression by hematoma or scar tissue, or devascularization.
  • Clinical Presentation: Weakness or inability to extend the fingers at the MCP joints, weakness of wrist extension (especially ulnar deviation due to intact ECRL/B), and inability to extend the thumb. Sensory loss is typically absent as PIN is a purely motor nerve.
  • Management:
    • Immediate Post-Op: Rule out mechanical compression from dressing/splint. Monitor clinical function closely.
    • Observation: Most iatrogenic PIN palsies are neurapraxias and resolve spontaneously within 3-6 months. Splinting to prevent contractures is essential.
    • Electrodiagnostic Studies (EMG/NCS): If no improvement after 6-8 weeks, these studies help confirm the diagnosis and provide prognostic information.
    • Nerve Exploration: Indicated if there is no evidence of recovery after 3-6 months, or if EMG/NCS suggests a more severe injury (axonotmesis or neurotmesis). Exploration aims to decompress, neurolyse, or repair the nerve.
• Superficial Radial Nerve Irritation: Less common, but can result from direct trauma, entrapment in scar tissue, or suture involvement. Presents as pain, numbness, or paresthesias on the dorsum of the hand.
  • Management: Observation, local injections, or in refractory cases, surgical neurolysis or neurectomy.

Nonunion or Delayed Union

• Incidence: Varies depending on fracture complexity and patient factors, typically 2-10%.
• Mechanism: Inadequate reduction, unstable fixation, extensive periosteal stripping, infection, poor bone quality, patient non-compliance.
• Management:
  • Delayed Union: Optimize rehabilitation, monitor.
  • Nonunion: Requires revision surgery, often with robust internal fixation, bone grafting (autograft from iliac crest or distal radius, allograft, or bone graft substitutes), and potentially biologic augmentation (e.g., PRP, BMPs).

Malunion

• Incidence: 5-15%, often subtle but can cause functional deficits (e.g., restricted forearm rotation).
• Mechanism: Inaccurate reduction, loss of reduction post-fixation. Rotational malunion is particularly problematic for the forearm.
• Management:
  • Asymptomatic Malunion: Observation.
  • Symptomatic Malunion: Corrective osteotomy and internal fixation to restore anatomical alignment and rotational profile.

Surgical Site Infection (SSI)

• Incidence: 1-3% for clean elective orthopedic procedures.
• Mechanism: Contamination during surgery, immunocompromised patient.
• Management:
  • Superficial Infection: Oral antibiotics, local wound care.
  • Deep Infection: Emergent surgical debridement, intravenous antibiotics based on culture results, retaining hardware if stable and infection can be controlled, or hardware removal if unstable or resistant.

Hardware-Related Issues

• Plate Prominence/Soft Tissue Irritation: Common, especially in thinner individuals.
• Screw Loosening/Breakage: Indicative of nonunion or excessive stress on the implant.
• Management: Hardware removal, usually after fracture union and resolution of symptoms.

Compartment Syndrome

• Incidence: Rare after isolated radial shaft ORIF (<1%), but an emergent consideration.
• Mechanism: Postoperative bleeding and swelling within the tight fascial compartments of the forearm.
• Management: Immediate clinical recognition and emergent fasciotomy.

Adhesions and Stiffness

• Mechanism: Scar tissue formation can restrict muscle glide and joint motion.
• Management: Aggressive physiotherapy and occupational therapy, sometimes requiring surgical adhesiolysis.

Common Complications and Salvage Strategies

Post Operative Rehabilitation Protocols

A structured and progressive rehabilitation protocol is integral to achieving optimal functional outcomes and minimizing long-term complications following the posterior radial approach. The protocol must be tailored to the specific pathology treated (fracture, osteotomy, nerve decompression), the stability of fixation, and individual patient factors.

Immediate Postoperative Phase (Days 0-2 weeks)

• Immobilization: The forearm is typically immobilized in a well-padded sugar tong splint or posterior splint, maintaining the elbow at 90 degrees of flexion and the wrist in a neutral to slight extension. This protects the surgical site, minimizes swelling, and provides initial stability.
• Pain and Edema Control:
  • Elevation of the limb above heart level.
  • Cryotherapy (ice packs).
  • Pharmacological pain management.
• Early Motion:
  • Finger ROM: Active range of motion (ROM) of the metacarpophalangeal (MCP) and interphalangeal (IP) joints of the hand and thumb is initiated immediately to prevent stiffness.
  • Shoulder ROM: Active-assisted and active ROM for the shoulder is encouraged to prevent shoulder stiffness.
  • Elbow ROM (Careful): Gentle active and active-assisted elbow flexion and extension can begin within the splint or with splint removal, if the fracture pattern and fixation are stable. Avoid pronation/supination to protect healing.
• Wound Care: Maintain a clean, dry wound. Monitor for signs of infection.

Early Mobilization and Strengthening Phase (Weeks 2-6)

• Splint Removal and Progressive ROM:
  • At approximately 2-3 weeks, the static splint is typically discontinued, and a removable brace or dynamic splint may be used for protection during activities.
  • Gradual initiation of active and passive ROM for the wrist and elbow.
  • Pronation/Supination: Controlled active and passive forearm pronation and supination are introduced cautiously, based on fracture stability and surgeon preference. The posterior approach does not disturb the interosseous membrane or forearm rotation directly, but internal fixation needs time for initial healing.
• Gentle Strengthening:
  • Begin isometric exercises for wrist extensors and flexors.
  • Light grip strengthening (e.g., squeezing a soft ball).
  • Initiate gentle resistive exercises for elbow flexion/extension.
• Scar Management: Gentle massage and silicone sheeting to minimize scar adhesion and hypertrophy.

Intermediate Rehabilitation Phase (Weeks 6-12)

• Radiographic Confirmation of Healing: Clinical and radiographic signs of early fracture healing (callus formation) are typically evident by 6-8 weeks.
• Progressive Strengthening:
  • Increased resistance exercises for wrist, elbow, and forearm musculature (e.g., using light weights, TheraBand).
  • Focus on full, pain-free ROM in all planes for the elbow, wrist, and forearm.
• Functional Activities: Incorporate functional exercises relevant to daily activities and work-related tasks.
• PIN Palsy Management: If PIN palsy occurred, continue nerve gliding exercises and consider dynamic splinting for finger extension to prevent contractures and aid function while awaiting nerve recovery.

Advanced Strengthening and Return to Activity (Weeks 12 onwards)

• Full Strength and Endurance: Focus on regaining full strength, endurance, and power.
• Sport-Specific/Work-Specific Training: For athletes or individuals with demanding occupations, incorporate sport- or work-specific training drills.
• Impact Loading: Gradually introduce impact loading activities.
• Hardware Removal Consideration: In younger, active individuals or if hardware prominence is symptomatic, hardware removal may be considered after 12-18 months, once bone healing is complete and mature. This is an elective procedure and not always necessary.
• Long-Term Monitoring: Continue to monitor for residual stiffness, pain, or nerve symptoms.

The rehabilitation process is dynamic and individualized. Close communication between the surgeon, physical therapist, and occupational therapist is critical to ensure appropriate progression and address any emerging issues.

Summary of Key Literature and Guidelines

The posterior approach to the radius is a well-established technique supported by decades of orthopedic literature, although often discussed in conjunction with general forearm fracture management rather than as a standalone topic. Its foundational principles align with general AO (Arbeitsgemeinschaft für Osteosynthesefragen) principles of fracture care, emphasizing anatomical reduction, stable internal fixation, and early, safe mobilization.

Biomechanical Rationale

Key biomechanical studies have elucidated the importance of plate position in forearm fractures. While volar plating is often favored for its ease of access and minimal nerve risk, dorsal plating is acknowledged for its biomechanical superiority in specific scenarios. Pioneering work by authors like Sarmiento and others on the "tensile side" of bone provided the rationale for dorsal plating on the extensor surface of the radius. This understanding reinforces that for unstable, comminuted radial shaft fractures, particularly in the mid to proximal third, a dorsal plate can effectively neutralize tensile forces, acting as a tension band to promote healing.

PIN Safety and Decompression Outcomes

Protecting the posterior interosseous nerve remains the paramount concern. Anatomic studies detailing the course of the PIN through the supinator and the variable morphology of the Arcade of Frohse (e.g., by Spinner and others) have underscored the need for meticulous, direct visualization. Literature on PIN decompression for conditions like resistant tennis elbow or nerve entrapment syndromes often cite the posterior approach as the preferred method, demonstrating good to excellent outcomes in relieving symptoms and restoring motor function. However, success rates vary depending on the etiology and chronicity of nerve compression.

Management of Radial Shaft Fractures

Consensus guidelines, such as those from the American Academy of Orthopaedic Surgeons (AAOS) and the Orthopaedic Trauma Association (OTA), recognize the posterior approach as a viable option for specific radial shaft fractures. While the volar approach (Henry approach) is generally the workhorse for most diaphyseal forearm fractures, the posterior approach is specifically indicated for:
* Fractures with significant dorsal comminution.
* Nonunions previously treated with a volar plate.
* Monteggia-equivalent fractures requiring stable proximal radial fixation.
* In situations where there is a contraindication to a volar approach.

Advanced Techniques and Future Directions

Recent advancements include the development of anatomically pre-contoured locking plates for the dorsal radius, which simplify surgical technique and improve fixation stability. Research continues into minimally invasive approaches, though these present increased challenges for PIN identification and protection. The use of patient-reported outcome measures (PROMs) is becoming standard in evaluating long-term functional results and patient satisfaction following these complex procedures. Ongoing investigations into biological adjuncts for fracture healing (e.g., growth factors, mesenchymal stem cells) may also further enhance outcomes for challenging nonunions treated via the posterior approach.

In conclusion, the posterior approach to the radius is a powerful tool in the armamentarium of the orthopedic surgeon. Its successful application hinges on a profound knowledge of surgical anatomy, meticulous dissection, unwavering attention to PIN protection, and sound biomechanical principles. Mastery of this approach ensures effective management of a range of complex radial pathologies, ultimately contributing to improved patient function and quality of life.

Clinical & Radiographic Imaging