+967-774203774 [email protected]
العربية

Tension Band Wiring Fixation for Patella Fractures

13 Apr 2026 21 min read 0 Views

Key Takeaway

Tension band wiring is the gold standard for displaced patella fractures. By converting anterior tensile forces into articular compressive forces during knee flexion, this AO technique ensures stable fixation and permits early range of motion. This guide details the biomechanical principles, step-by-step surgical execution using Kirschner wires or cannulated screws, and evidence-based postoperative rehabilitation protocols essential for optimal patient outcomes.

INTRODUCTION TO PATELLAR FRACTURE FIXATION

The patella is the largest sesamoid bone in the human body, serving a critical biomechanical role in the extensor mechanism of the knee. It increases the moment arm of the quadriceps tendon, thereby enhancing the mechanical advantage of knee extension by up to 30%. Fractures of the patella disrupt this vital mechanism, leading to profound functional impairment if not meticulously addressed.

The Arbeitsgemeinschaft für Osteosynthesefragen (AO) group has long advocated for the tension band wiring principle as the gold standard for the fixation of displaced transverse patellar fractures. When executed correctly, this technique neutralizes the distracting forces of the extensor mechanism and converts them into dynamic compressive forces across the articular surface during knee flexion. This biomechanical conversion is paramount, as it facilitates earlier union, allows for immediate postoperative motion, and mitigates the stiffness traditionally associated with prolonged immobilization.

Clinical Pearl: The success of tension band wiring relies entirely on the integrity of the opposite cortex (the articular surface). If the articular surface is severely comminuted and cannot provide a stable buttress, the tension band principle will fail, leading to fracture displacement and hardware failure.

BIOMECHANICAL PRINCIPLES OF THE TENSION BAND

To master the tension band wiring technique, the surgeon must first understand the forces acting upon the patella. The patella is subjected to massive tensile forces anteriorly, generated by the pull of the quadriceps muscle against the resistance of the patellar tendon.

When a transverse fracture occurs, these forces distract the anterior cortex. By placing a stout wire loop (the tension band) on the anterior surface of the patella, the surgeon creates a mechanical restraint. As the knee flexes, the tension band resists anterior gapping. Because the anterior cortex cannot distract, the force is redirected through the fulcrum of the bone, resulting in compression at the articular surface.

For the tension band principle to function optimally:
* The tension band must be applied to the tension surface (anteriorly).
* The bone must be able to withstand compression on the opposite surface (articular cartilage).
* The fixation must be secure enough to withstand the physiological loads of early active mobilization.

INDICATIONS AND PREOPERATIVE PLANNING

Indications for Operative Intervention

Not all patellar fractures require surgery. However, operative fixation via tension band wiring is strictly indicated in the presence of:
* Displacement of the fracture fragments greater than 3 mm.
* Articular step-off or incongruity greater than 2 mm.
* Disruption of the extensor mechanism (inability to perform a straight leg raise).
* Open fractures requiring immediate debridement and stabilization.

Preoperative Assessment

Standard anteroposterior (AP), lateral, and axial (skyline) radiographs are mandatory. The lateral view is particularly critical for assessing the degree of displacement and comminution. In cases of high-energy trauma or suspected osteochondral shearing, a CT scan may be warranted to fully delineate the fracture pattern and plan for supplemental screw fixation.

SURGICAL ANATOMY AND POSITIONING

Patient Positioning

The patient is placed in the supine position on a radiolucent operating table. A tourniquet is applied to the proximal thigh to ensure a bloodless surgical field, which is critical for identifying small articular fragments and assessing retinacular tears. A small bump may be placed under the ipsilateral hip to correct natural external rotation, ensuring the patella faces directly anteriorly. The limb is prepped and draped free to allow full, unrestricted flexion and extension of the knee during the procedure.

Surgical Approach

A midline longitudinal incision is universally preferred over transverse incisions. The longitudinal approach is extensile, respects the vascular supply to the skin flaps, and can be easily incorporated into a standard midline arthrotomy should the patient require total knee arthroplasty in the future.

The incision extends from the superior pole of the patella to the tibial tubercle. Full-thickness fasciocutaneous flaps are elevated medially and laterally to expose the entire anterior surface of the patella and the medial and lateral extensor retinacula.

SURGICAL TECHNIQUE 54-21: STANDARD TENSION BAND WIRING

The following represents the definitive, step-by-step execution of the AO tension band wiring technique using Kirschner wires (K-wires).

1. Joint Preparation and Debridement

Approach the patellar fracture in the usual fashion. Carefully clean the fracture surfaces of all organized blood clots, fibrin, and interposed soft tissue. Small, devitalized, non-articular fragments that impede reduction should be excised. Explore the full extent of the medial and lateral retinacular tears. Inspect the trochlear groove of the femur for any concomitant osteochondral damage. Thoroughly lavage the joint with sterile saline to remove intra-articular hematoma and debris.

2. Fracture Reduction

If the major proximal and distal fragments are large, reduce them accurately. Special attention must be directed toward restoring a perfectly smooth articular surface. Reduction is typically achieved using large, pointed reduction forceps (Weber clamps) applied to the superior and inferior poles.

Surgical Warning: Do not rely solely on the anterior cortical reduction. The anterior surface of the patella is naturally irregular. Anatomical reduction must be confirmed by palpating the articular surface through the retinacular tears.

3. Kirschner Wire Insertion

With the fracture anatomically reduced and held firmly with clamps, drill two 2.0-mm K-wires from inferior to superior through each fragment.
* Place these wires approximately 5 mm deep to the anterior surface of the patella.
* Position them along lines dividing the patella into medial, central, and lateral thirds.
* It is imperative to insert the wires as parallel as possible to facilitate uniform compression and prevent binding.

Alternative Retrograde Technique: In cases of difficult reduction, it is often easier to insert the K-wires through the fracture site into the proximal fragment in a retrograde manner before reduction. This is made easier by tilting the proximal fracture fragment anteriorly about 90 degrees. Once the wires pierce the superior pole, they are withdrawn until flush with the fracture site. The fracture is then reduced, clamped, and the wires are driven antegrade into the distal fragment.

Leave the ends of the K-wires long, protruding beyond the patella and the quadriceps/patellar tendon attachments.

4. Application of the Tension Band Wire

Pass a strand of 18-gauge stainless steel wire transversely through the quadriceps tendon attachment, as close to the superior bone pole as possible, passing deep to the protruding K-wires.

Route the wire over the anterior surface of the reduced patella. Pass it transversely through the patellar tendon attachment on the inferior fragment, again keeping it deep to the protruding K-wires and as close to the bone as possible. Bring the wire back over the anterior patellar surface to meet the upper end.

While a simple loop can be used, placing the wire in a figure-of-eight fashion is biomechanically superior, as it provides better rotational stability and more uniform compression across the fracture site.

TENSION BAND WIRING FIXATION Surgical Diagram

5. Tensioning and Verification

Tighten the 18-gauge wire symmetrically. The wire should be tightened until the fracture is slightly overcorrected (opened microscopically on the anterior surface), ensuring maximum compression at the articular surface.

Check the reduction by palpating the undersurface of the patella with the knee fully extended. If the retinacular tears are insufficient to allow a finger into the joint, make a small, deliberate longitudinal incision in the retinaculum to permit digital palpation of the articular step-off.

6. Securing the Hardware

Once compression is confirmed, the K-wires must be secured to prevent postoperative migration—a common complication.
* Bend the upper ends of the two K-wires acutely anteriorly (approximately 180 degrees).
* Cut the bent ends short.
* Using a heavy impactor and mallet, embed the bent ends deep into the superior margin of the patella, ensuring they sit posterior to the wire loops. This locks the tension band in place.
* Cut the protruding ends of the K-wires short inferiorly, leaving just enough length to prevent the wire loop from slipping off, but short enough to avoid irritating the patellar tendon.

7. Retinacular Repair

The operation is not complete until the extensor mechanism is fully restored. Repair the medial and lateral retinacular tears meticulously using multiple interrupted heavy non-absorbable or slowly absorbable sutures (e.g., #1 or #2 Vicryl).

ADVANCED MODIFICATIONS FOR COMPLEX FRACTURES

The Schauwecker Technique for Comminuted Fractures

Standard tension band wiring is designed for simple transverse fractures. When comminution is present, the tension band alone may cause the fracture to collapse or telescope, leading to articular incongruity.

Schauwecker described a highly effective method of compression wiring using supplemental lag screws for comminuted fractures. The principle is to convert a multi-fragmentary fracture into a stable, bifragmental fracture before applying the tension band.

FIGURE 54-63 A-C, Schauwecker method of com­ pression wiring of patella using supplemental screws for comminuted fracture (C) . Comminuted fragments (A) are transformed with screws into bifragmental fracture (B) . SEE TECHNIQUE 54-21.

  1. Fragment Assembly: The comminuted fragments (usually at the inferior or superior pole) are anatomically reduced.
  2. Lag Screw Fixation: Mini-fragment lag screws (2.0 mm or 2.7 mm) are placed horizontally or obliquely to compress the comminuted fragments together. This effectively transforms the comminuted fracture into a simple transverse pattern.

TENSION BAND WIRING FIXATION Surgical Diagram

  1. Tension Band Application: Once the fracture is bifragmental, a standard figure-of-eight tension band wire is applied over the anterior surface of the patella to neutralize the extensor forces.

TENSION BAND WIRING FIXATION Surgical Diagram

If the anterior cortex is split from the articular surface in the coronal plane, the fragment usually can be secured with the anterior tension band wire. If this is unsuccessful and the fragment is small and non-articular, it can be excised.

Cannulated Screw Tension Band Construct

A modern, highly favored alternative to K-wires involves the use of 4.0-mm partially threaded cannulated screws. This technique offers superior biomechanical strength and significantly reduces the incidence of symptomatic hardware prominence.

Instead of driving K-wires, two 4.0-mm cannulated screws are placed longitudinally from inferior to superior across the reduced fracture. These screws provide independent interfragmentary compression. The 18-gauge tension band wire is then passed directly through the hollow cannulae of the screws, rather than around protruding K-wire ends.

TENSION BAND WIRING FIXATION Surgical Diagram

TENSION BAND WIRING FIXATION Surgical Diagram

This construct creates a highly stable, low-profile fixation. The screws compress the articular surface, while the wire through the screws acts as the anterior tension band, neutralizing the distracting forces of the quadriceps.

POSTOPERATIVE CARE AND REHABILITATION

The success of patellar fracture fixation is heavily dependent on a structured, phased postoperative rehabilitation protocol. The tension band principle relies on early active flexion to produce compressive forces; however, the surgeon must balance this against the risk of fixation failure.

Phase I: Immediate Postoperative Period (Days 1-14)

  • Immobilization: The limb is placed in full extension in a posterior plaster splint or a hinged, removable knee brace locked in extension.
  • Weight-Bearing: The patient is allowed to ambulate while bearing weight as tolerated (WBAT) on the first postoperative day, provided the knee is locked in extension.
  • Exercises: Isometric quadriceps sets and straight-leg raises (stiff-leg exercises) are encouraged immediately, beginning on postoperative day one. This prevents quadriceps atrophy and prevents adhesions in the suprapatellar pouch.
  • Motion: The extent of active motion permitted in the immediate postoperative period is determined intraoperatively based on the stability of the fracture repair. If fixation is rock-solid, passive motion from 0 to 30 degrees may be initiated.

Phase II: Early Motion (Weeks 2-6)

  • Active and active-assisted range-of-motion (ROM) exercises can be formally initiated when the surgical wound has healed, typically at 2 to 3 weeks.
  • A controlled motion knee brace is highly recommended. The brace allows full extension and limits flexion to the degree permitted by the fixation (often starting at 0-45 degrees and advancing 15 degrees weekly).
  • Caveat: In patients with less stable fixation, severe comminution, or extensive retinacular tears, active motion should be delayed until early fracture healing is evident radiographically. Initiating ROM exercises by the sixth postoperative week is desirable to prevent arthrofibrosis, but it is not always possible if stability is questionable.

Phase III: Strengthening and Return to Function (Weeks 6-24)

  • Weeks 6-8: If clinical and radiographic healing is evident, the hinged knee brace can be discontinued. Progressive resistance exercises (closed kinetic chain) are initiated.
  • Weeks 18-24: Unrestricted activity, including sports and heavy manual labor, can be resumed only when full, symmetric quadriceps strength has returned and the fracture is fully consolidated.

COMPLICATIONS AND REVISION SURGERY

Despite meticulous technique, complications can arise following tension band wiring of the patella.

Hardware Prominence and Irritation

The most common complication is symptomatic hardware, occurring in up to 40% of patients treated with traditional K-wires. The proximal K-wire ends or the wire knot can irritate the overlying skin and quadriceps tendon. Hardware can be safely removed after complete radiographic healing of the fracture (typically after 6 to 12 months) if it causes persistent symptoms. The use of cannulated screws significantly reduces this complication.

Loss of Fixation

Loss of reduction is a severe complication that demands immediate reassessment. If the fixation is lost and the fragments separate by 3 to 4 mm, or if 2 to 3 mm of articular incongruity develops, revision surgery is frequently required.

Clinical Pearl: If postoperative displacement occurs, examine the patient with the knee in full extension. If the reduction improves and the articular step-off resolves in extension, the patient can be treated conservatively by 6 weeks of rigid splinting or casting in full extension.

If the reduction does not improve in extension, revision open reduction and internal fixation (ORIF) is mandatory. In cases of catastrophic failure where the bone is too osteoporotic or comminuted to hold new hardware, a partial or total patellectomy must be considered as a salvage procedure, though this will result in a permanent extensor lag and decreased quadriceps power.

Infection and Nonunion

Superficial infections are managed with oral antibiotics, while deep infections require prompt surgical irrigation and debridement. Nonunion is rare (less than 2%) due to the excellent vascular supply of the patella, but when it occurs, it is usually the result of inadequate fixation or premature aggressive rehabilitation. Treatment requires revision ORIF with bone grafting.

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
Article Contents