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Operative Management of Patellar Fractures: A Comprehensive Surgical Guide

13 Apr 2026 13 min read 0 Views

Key Takeaway

Surgical management of patellar fractures requires meticulous attention to soft tissue handling, anatomical articular reduction, and stable internal fixation. This comprehensive guide details the standard longitudinal and transverse surgical approaches, joint debridement, and retinacular repair techniques. By restoring the extensor mechanism and achieving absolute stability, surgeons can facilitate early postoperative mobilization, thereby minimizing stiffness and optimizing functional outcomes in complex patellofemoral trauma.

INTRODUCTION AND SURGICAL RATIONALE

Patellar fractures account for approximately 1% of all skeletal injuries and present a unique challenge to the orthopedic surgeon due to the bone’s critical role in the extensor mechanism of the knee. As the largest sesamoid bone in the human body, the patella serves to increase the mechanical advantage of the quadriceps muscle by displacing the tendon anteriorly, thereby increasing the moment arm.

The primary goals of operative intervention in patellar fractures are the anatomical restoration of the articular surface to prevent post-traumatic patellofemoral osteoarthritis, the rigid internal fixation of the fracture fragments to allow for early range of motion (ROM), and the meticulous repair of the extensor retinaculum. Failure to achieve these objectives can result in profound functional deficits, including extensor lag, profound knee stiffness, anterior knee pain, and early-onset degenerative joint disease.

SURGICAL ANATOMY AND BIOMECHANICS

A profound understanding of patellofemoral biomechanics and vascular anatomy is mandatory for successful surgical outcomes.

The patella increases the moment arm of the quadriceps mechanism by up to 30%. During knee flexion, patellofemoral joint reaction forces increase exponentially, reaching up to seven times body weight during deep squatting. Consequently, any internal fixation construct must be robust enough to withstand these immense tensile forces across the anterior cortex while converting them into compressive forces at the articular surface (the tension band principle).

The vascular supply to the patella is primarily derived from an extraosseous anastomotic ring formed by the superior and inferior genicular arteries. The dominant intraosseous blood supply enters the distal pole. Surgical approaches and dissection must respect this vascular network to mitigate the risk of avascular necrosis (AVN) or delayed union, particularly in highly comminuted fracture patterns.

💡 Clinical Pearl: The Extensor Retinaculum

The medial and lateral retinacula are vital secondary extensors of the knee. In displaced patellar fractures, the retinaculum is almost universally torn. Even if the bony patella is perfectly reduced, failure to meticulously repair the retinacular tears will result in a persistent extensor lag and compromised patellar tracking.

PREOPERATIVE PLANNING AND INDICATIONS

Indications for Operative Intervention

Nonoperative management is strictly reserved for non-displaced fractures with an intact extensor mechanism. Operative intervention is indicated for:
* Fracture displacement greater than 3 mm.
* Articular step-off greater than 2 mm.
* Disruption of the extensor mechanism (inability to perform a straight leg raise).
* Open fractures requiring urgent irrigation and debridement.
* Osteochondral fractures with intra-articular loose bodies.

Preoperative Imaging

Standard radiographic evaluation includes anteroposterior (AP), lateral, and skyline (Merchant) views. The lateral view is critical for assessing the degree of displacement and comminution. In cases of high-energy trauma or severe comminution (e.g., stellate fractures), a preoperative computed tomography (CT) scan with 3D reconstruction is highly recommended to map articular impaction and plan plate contouring or screw trajectory.

PATIENT POSITIONING AND PREPARATION

  1. Positioning: The patient is placed in the supine position on a radiolucent operating table.
  2. Tourniquet: A high-thigh pneumatic tourniquet is applied. Exsanguination and tourniquet inflation are typically performed, though some surgeons prefer to inflate the tourniquet only if visualization becomes compromised, thereby minimizing ischemic time to the quadriceps.
  3. Draping: The limb is prepped and draped free to allow for full, unrestricted flexion and extension of the knee during the procedure. This is critical for assessing the stability of the fixation and the tracking of the patella.
  4. Fluoroscopy: The C-arm should be positioned on the contralateral side of the table, ensuring orthogonal views (AP and lateral) can be obtained effortlessly throughout the procedure.

SURGICAL APPROACH AND EXPOSURE

The choice of surgical incision is dictated by the fracture pattern, the condition of the soft tissues, and the patient's future orthopedic needs.

Incision Selection

  • Longitudinal Midline Incision (Preferred): Make a longitudinal midline or lateral parapatellar incision. This is the gold standard approach, especially if the fracture is comminuted or if future joint replacement (Total Knee Arthroplasty) is anticipated. A longitudinal incision is extensile, respects the vascular supply of the anterior knee skin flaps, and avoids the creation of intersecting scars should subsequent surgeries be required.
  • Transverse Curved Incision (Alternative): Alternatively, a transverse curved incision can be made approximately 12.5 cm long with the apex of the curve resting on the distal fragment. This approach follows Langer’s lines, offering superior cosmesis, and provides excellent exposure for the reduction of the fracture and the repair of the ruptured extensor expansion and synovium. However, it carries a higher risk of injuring the infrapatellar branch of the saphenous nerve, leading to lateral cutaneous numbness.

⚠️ Surgical Warning: Soft Tissue Handling

If an area of skin is severely contused or abraded from the initial trauma, attempt to avoid it during your incision planning. If avoidance is impossible, elect to excise a small area of the non-viable skin; skin closure over the anterior knee is generally robust and produces no significant difficulty, whereas leaving necrotic skin invites deep surgical site infections.

Soft Tissue Dissection and Flap Creation

Once the incision is made, reflect the skin and subcutaneous tissue proximally and distally as full-thickness flaps. It is imperative to stay in the pre-bursal plane to preserve the subdermal vascular plexus.

Expose the entire anterior surface of the patella, the distal quadriceps tendon, and the proximal patellar tendon. If the fracture fragments are significantly separated, tears in the extensor expansion (retinaculum) are presumed to be present. These must be carefully explored medially and laterally. The hematoma within these tears often guides the surgeon directly to the extent of the retinacular disruption.

JOINT INSPECTION AND DEBRIDEMENT

Before any attempt at reduction is made, the joint must be thoroughly prepared.

  1. Hematoma Evacuation: Thoroughly irrigate the interior of the joint with sterile saline to remove all fracture hematoma, blood clots, and small particles of bone. A bulb syringe or low-pressure pulse lavage is highly effective.
  2. Fragment Excision: Remove all small, detached, and avascular fragments of bone that cannot be incorporated into the fixation construct. Retaining devitalized fragments increases the risk of third-body wear and post-traumatic arthritis.
  3. Articular Inspection: Inspect the interior of the joint, paying special attention to the patellofemoral groove (trochlea) and the weight-bearing surfaces of the femoral condyles for associated osteochondral fractures or impaction injuries.

FRACTURE REDUCTION TECHNIQUES

Achieving an absolute anatomical reduction of the articular surface is the most critical step of the procedure.

  1. Joint Exposure: Flex the knee to 90 degrees to expose the articular surface of the patella and the trochlea.
  2. Mobilization: Extend the knee fully to relax the quadriceps mechanism, which facilitates the approximation of the major fracture fragments.
  3. Clamping: Anatomically reduce the fracture fragments using large towel clips or appropriate bone-holding forceps (e.g., Weber pointed reduction clamps). Place the tines of the clamp on the superior and inferior poles of the patella.
  4. Articular Assessment: Inspect the articular surface after provisional fixation to ensure that the reduction is anatomical. This can be done by passing a gloved finger through the medial or lateral retinacular tear to directly palpate the articular cartilage. There should be absolutely no step-off.
  5. Fluoroscopic Confirmation: Obtain a lateral fluoroscopic view to confirm the restoration of the anterior cortex and the articular surface.

💡 Clinical Pearl: The "Open Book" Technique

For complex, multi-fragmentary fractures, consider everting the major fragments (the "open book" technique) to directly visualize the articular surface. Small articular fragments can be reduced and provisionally fixed with 1.0 mm Kirschner wires (K-wires) from the articular side before closing the "book" and applying the definitive reduction clamp.

INTERNAL FIXATION STRATEGIES

Once anatomical reduction is achieved, fix the fragments internally by the method preferred by the surgeon, dictated by the specific fracture morphology.

Modified Tension Band Wiring (AO Technique)

This remains the classic and most widely utilized technique for simple transverse fractures.
* Two parallel 1.6 mm or 2.0 mm K-wires are driven from the proximal pole to the distal pole, staying in the anterior half of the patella to maximize the tension band effect.
* An 18-gauge stainless steel wire is passed behind the K-wires proximally and distally in a figure-of-eight fashion over the anterior surface of the patella.
* The wire is tensioned symmetrically using two tensioning loops to ensure even compression across the fracture site.
* The K-wires are bent, cut short, and impacted into the superior pole to prevent symptomatic hardware prominence.

Cannulated Screws with Tension Band

For transverse fractures, replacing K-wires with cannulated lag screws (typically 4.0 mm or 4.5 mm) offers superior biomechanical stability.
* The screws provide interfragmentary compression.
* An 18-gauge wire is then passed through the cannulae of the screws and crossed in a figure-of-eight over the anterior cortex.
* This construct significantly reduces the risk of hardware migration and provides a more rigid fixation, allowing for aggressive early rehabilitation.

Anterior Locked Plating

Modern osteosynthesis has seen a shift toward low-profile, anatomically contoured locking plates, particularly for comminuted (stellate) fractures or osteoporotic bone.
* Mesh plates or star-shaped locking plates provide multi-planar stability.
* Fixed-angle locking screws prevent the collapse of comminuted fragments and offer superior pull-out strength compared to traditional wiring techniques.
* Plating is increasingly becoming the standard of care for multi-fragmentary fractures where a tension band wire would fail to control rotational forces or comminution.

Partial Patellectomy

In cases where the distal or proximal pole is severely comminuted and cannot be reconstructed, a partial patellectomy may be necessary.
* The comminuted fragments are excised.
* The patellar or quadriceps tendon is advanced and reattached to the remaining healthy patellar bone using heavy non-absorbable transosseous sutures or suture anchors.
* Care must be taken to preserve the length of the extensor mechanism to prevent patella baja or alta.

RETINACULAR REPAIR AND CLOSURE

The bony fixation is only half of the operation; the soft tissue reconstruction is equally vital.

  1. Dynamic Testing: Before closure, the knee must be taken through a full range of motion under direct visualization. The fracture fixation must remain absolutely stable, and the articular surface must not gap during deep flexion.
  2. Retinacular Repair: Carefully repair the synovium, ruptured capsule, and extensor mechanism using heavy, interrupted, non-absorbable sutures (e.g., #2 FiberWire or Ethibond).
  3. Suturing Technique: Begin the repair from the outer (peripheral) ends of the retinacular tears and work toward the midline of the joint. This ensures proper tensioning and prevents bunching of the tissue.
  4. Wound Closure: Thoroughly irrigate the subcutaneous tissues. Close the pre-bursal subcutaneous layer with absorbable sutures to eliminate dead space. Close the skin with staples or a subcuticular suture based on surgeon preference and skin viability.
  5. Dressings: Apply a sterile, non-adherent dressing followed by a compressive Jones bandage. Place the limb in a hinged knee brace locked in full extension.

POSTOPERATIVE REHABILITATION PROTOCOL

The rehabilitation protocol is dictated by the security of the internal fixation and the quality of the patient's bone.

  • Phase I (0-2 Weeks): The knee is immobilized in full extension for weight-bearing activities to protect the retinacular repair. Isometric quadriceps exercises (quad sets) and straight leg raises are initiated immediately to prevent muscle atrophy. Passive range of motion (PROM) from 0 to 30 degrees may be initiated if the fixation is deemed absolutely rigid.
  • Phase II (2-6 Weeks): The hinged knee brace is gradually unlocked to allow progressive active-assisted range of motion (AAROM). Flexion is typically advanced by 15 to 30 degrees per week. Weight-bearing is progressed as tolerated with the brace locked in extension.
  • Phase III (6-12 Weeks): Once radiographic evidence of early union is observed, the brace is discontinued. Progressive resistance exercises are initiated. Full weight-bearing without restrictions is permitted.
  • Phase IV (3-6 Months): Focus shifts to functional rehabilitation, proprioception, and return to pre-injury activities. Maximum medical improvement is typically reached between 6 and 12 months postoperatively.

COMPLICATIONS AND PITFALLS

Despite meticulous surgical technique, complications can occur:

  • Symptomatic Hardware: The most common complication, occurring in up to 30-50% of patients treated with traditional tension band wiring. The prominent K-wires or wire knots irritate the overlying skin, necessitating hardware removal after fracture consolidation (typically after 6-12 months).
  • Loss of Fixation / Nonunion: Often due to technical errors (e.g., asymmetric tensioning of the wire, failure to recognize comminution) or patient non-compliance. Requires revision open reduction and internal fixation (ORIF), often utilizing locking plates or bone grafting.
  • Knee Stiffness: Arthrofibrosis is a significant risk if prolonged immobilization is utilized. Early, controlled mobilization is the best preventative measure.
  • Infection: Deep surgical site infections require urgent irrigation and debridement. Suppressive antibiotics may be necessary until the fracture heals, at which point the hardware must be removed.
  • Post-Traumatic Osteoarthritis: Directly correlated with the quality of the articular reduction. Even with perfect anatomical reduction, the initial chondral injury can lead to long-term degenerative changes.
Authoritative Medical Review

This academic synthesis is based on established protocols from Hutaifortho's Operative Orthopaedics and has been medically reviewed by Prof. Dr. Mohammed Hutaif, Consultant Orthopedic & Spine Surgeon. It is designed to assist orthopedic residents, fellows, and practicing surgeons in surgical preparation and board reviews (AAOS, FRCS, Arab Board).

Clinical Disclaimer: The surgical techniques, indications, and medical guidance detailed herein are for advanced educational purposes only. They do not supersede institutional guidelines or independent surgical judgment.

📚 Medical References

Dr. Mohammed Hutaif
Medically Verified Content
Prof. Dr. Mohammed Hutaif
Consultant Orthopedic & Spine Surgeon
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