Patella Fractures: Approach to Treatment

Damayea I. Hargett, MD; Brent R. Sanderson, DO; Milton T.M. Little, MD

Disclosures

J Am Acad Orthop Surg. 2021;29(6):244-253. 

In This Article

Tension Band Construct Fixation

Tension-band construct is the most common surgical technique for patellar fractures. The technique converts the anterior tension forces produced by the extensor mechanism and knee flexion into compression forces at the articular surface. Two 2.0 mm K-wires are placed perpendicular to the fracture line along the subchondral surface after fracture reduction. A metal low-gauge wire tension band is applied in a figure eight-shaped manner to compress the fracture. The ends of the K-wires are bent and buried in the proximal and distal aspects of the patella. The tension band wires are then twisted and buried in the patella. Prominent hardware in tension band wiring has led to hardware removal rates reported as high as 31.6%.[16] This has led to a progressive evolution in the fixation technique.

Improved longitudinal stabilization of the patellar fracture with the use of screw fixation rather than K-wires was the first advancement of the tension band. Screws provide greater rigidity and improved resistance against tensile loading when compared with K-wires. The modified tension band construct with cannulated screws has been shown to be superior in preventing fracture displacement and improving bending strength.[17–19]

The tension-band technique has continued to evolve with the introduction of braided and nonabsorbable sutures. Replacement of low gauge wire with high strength sutures has demonstrated comparable strength and improved stress distribution while limiting soft-tissue irritation.[20–22] Nonabsorbable braided suture or tape has also been used to replace wire for this construct and has been shown to display less creep, greater stiffness, and less extensibility than other sutures.[23] Utilization of braided/nonabsorbable sutures has decreased the overall risk of revision surgery and wound compromise.[21,24,25] In a recent retrospective report on fixation using headed cannulated screws with high strength nonabsorbable suture, Busel and colleagues showed high union rates at 96% and a low rate of symptomatic hardware at 8%. Three of the four cases of symptomatic hardware were due to screw prominence.[26]

The ultimate goal of the tension band technique is a biomechanically superior construct with little hardware irritation that will allow for early rehabilitation and range of motion. Screw fixation has also evolved along with the high strength suture incorporation. Screw head prominence has been shown to reduce the constructs ability to resist gap formation during cyclic loading testing.[27] Dual-pitched buried compression screws with suture tension band demonstrated superior biomechanical behaviors over standard headed screw fixation including increased construct rigidity, smaller interfragmentary motion, increased resistance to failure, and greater fixation strength. Martin et al[28] showed that the mean clinical failure strength for the headless screws construct was almost double that of the headed screws construct. Alayan et al[29] demonstrated comparable fixation; however, greater fracture gapping was found with buried compression screws and suture fixation compared with wire/cannulated screw constructs. Further clinical comparison of these techniques is still indicated.

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