Introduction to Patellar Fractures
Mechanisms of Injury
Signs and Symptoms
Imaging and Other Diagnostic Studies
Pathoanatomy and Applied Anatomy
Arterial Blood Supply
Soft Tissue Anatomy
Author’s Preferred Method of Treatment
Patients with an Intact Extensor Mechanism, Vertical Fractures, and Minimal Articular Displacement or Patients Unfit for Anesthesia
Introduction to Extensor Mechanism Injuries
Author’s Preferred Techniques
Quadriceps tendon rupture
Acute Patellar Tendon Rupture
Tibial Tubercle Avulsions
Acute Patellar Dislocations
Author’s Preferred Technique
Management of Expected Adverse Outcomes and Unexpected Complications
Loss of Knee Motion
Extensor Mechanism Weakness
Symptomatic Retained Hardware
Infection and Wound Complications
Loss of Fixation/Refracture/Rerupture
Delayed Union and Nonunion
Summary, Controversies, and Future Directions
In these situations, we employ nonoperative care (Fig. 54-8). The exception is the patient with normal extensor mechanism function, but with significant articular incongruity or fracture gap. In patients with a large traumatic hemarthrosis, we will consider aspiration of the joint and injection of a local anesthetic to facilitate physical examination.
With compliant and reliable patients, we use a hinged knee brace locked in full extension. The brace is lightweight, allows for patient hygiene and monitoring of any abrasions or associated soft tissue injuries. Furthermore, controlled range of motion may be initiated once fracture callus is radiographically confirmed. In patients with questionable compliance or elderly patients who are at significant risk for falls, we prefer to utilize a fiberglass cylinder cast applied from the groin to just above the ankle, molded with the knee in full extension. Care must be taken, particularly in elderly or diabetic patients, to pad carefully to avoid iatrogenic soft tissue injury from a poorly molded cast. In patients with lower-extremity venous stasis ulcers or compromised circulation, an Unna boot can be applied prior to cast molding to protect the soft tissues.
Isometric quadriceps exercises with straight-leg raises are initiated 1 week after immobilization to minimize quadriceps atrophy. Partial weight bearing with crutch assistance is allowed immediately with advancement to full weight bearing in extension as tolerated. Follow-up radiographs are obtained at regular intervals to confirm that reduction has been maintained. If fracture displacement occurs early, surgical stabilization should be considered. After fracture consolidation is radiographically confirmed, controlled range of motion of the knee is initiated.
Marginal or small nonarticular fractures of the patella are often stable due to the preserved integrity of the soft tissues. In these cases, cast or brace immobilization is often unnecessary, and early, controlled range of motion with activity modification is initiated as tolerated.
Preoperative planning is often difficult with patellar fractures as the fracture lines and comminution are not always clearly visualized using standard imaging. It is imperative to have all of the necessary equipment available in the operating room to perform either internal fixation or a partial patellectomy. At minimum, small and mini-fragment implant sets with 3.5- and 2.7-mm cortical screws for interfragmentary fixation, 1.6- and 2-mm Kirschner wires, 18-gauge wire, and 14- or 16-gauge angiocatheters for wire passage are needed. A 4-mm cannulated screw set can be made available as well to fix transverse fracture patterns. Small and medium pointed reduction forceps are helpful for maintaining a provisional reduction. A power drill with wire driver attachment and wire twisters should be available. If significant distal pole comminution is encountered, a partial patellectomy may be necessary. A Hewson suture passer may be helpful for passing suture through bone tunnels if a partial patellectomy is performed.
In the case of open injuries, immediate irrigation and debridement of the fracture is performed followed by rigid internal fixation for Type I and II open injuries without gross contamination. Appropriate antibiotic coverage is selected, and serial debridement and/or soft tissue coverage are performed based on the contamination of the wound and the status of the soft tissues. If there is a question of an open fracture or traumatic arthrotomy, a saline load test should be performed in the emergency department. For closed fractures, the status of the skin and soft tissues helps guide the timing of operative intervention. Typically, we will wait 1 to 2 weeks in the setting of significant soft tissue swelling or superficial abrasions to minimize the risk of postoperative wound complications.
We perform the procedure with the patient supine on a radiolucent table. Intraoperative fluoroscopy is used to obtain true AP and lateral images. A high nonsterile thigh tourniquet is placed, but rarely inflated. The fracture is approached through a longitudinal midline incision with full-thickness skin flaps and minimal superficial dissection. This extensile approach provides excellent exposure of the fracture as well as the medial and lateral retinacular tears.
The fracture lines are carefully defined by debridement of clot and devitalized debris. In the setting of transverse fracture patterns (OTA C1.1), we prefer a cannulated screw tension band construct (Fig. 54-7). With more complex fractures in which the larger fragments have additional fracture lines (OTA C2.1), we attempt to simplify the fracture into a transverse pattern by securing the smaller fragments together with interfragmentary screws or K-wires. Screws of various sizes may be necessary based on fragment size and bone quality. Purely longitudinal fractures (OTA B1.1, B1.2, B2.1, B2.2) can often be secured with interfragmentary screws alone.
Provisional reduction of the fracture is obtained with the assistance of a pointed reduction forceps and manual manipulation. The reduction is assessed by both direct palpation of the articular surface through the retinacular tear and multiplanar fluoroscopy. If the retinacular tissues are intact, we create a small arthrotomy in the medial retinaculum to allow direct palpation of the articular surface. Guidewires for cannulated screws are placed in a retrograde fashion via the fracture line into the proximal pole. We prefer this technique to assure a depth 5 mm posterior to the anterior cortical surface. After drilling, the parallel screws are placed over the guidewires, conferring compression and rotational stability to the construct. The screw lengths are confirmed under fluoroscopy to avoid leaving the screw tips proud. The 18-gauge wire is then passed in a figure-of-eight fashion through the cannulated screws and the free limbs are twisted to achieve appropriate tension. The ends are then cut and bent backward into the patellar bone to minimize subcutaneous irritation from the wire.
In the setting of a displaced, stellate fracture pattern in which anterior tension banding is not feasible (OTA C3.1, C3.2), we will utilize indirect reduction with cerclage wiring followed by the longitudinal anterior banding technique of Lotke and Ecker102 With severe inferior pole comminution that is not salvageable (OTA C1.3, C2.3), we perform a partial patellectomy while attempting to preserve as much of the remaining patella as possible. Interfragmentary screws may be utilized to stabilize large salvageable independent fragments. Two locking Krackow sutures are then run in the patellar tendon, resulting in four core strands which are passed through three tunnels in the residual patella. The drill holes are placed at the articular margin to avoid iatrogenic patellar tilt. A burr or rongeur is used to make a small trough at the inferior margin of the patella to allow tendon apposition against bleeding, cancellous bone. We typically protect the partial patellectomy with an 18-gauge cerclage wire passed superior to the patella across the quadriceps tendon and through the proximal tibia.
For fractures with stable internal fixation, we recommend early physiotherapy and weight bearing as tolerated while limiting flexion to 30 degrees for 4 weeks at which time range of motion is progressed. When fixation is tenuous, when partial patellectomy is performed, or when the patient is noncompliant, full weight bearing in a cylinder cast in extension for 6 weeks is instituted prior to progression to a hinged knee brace. Isometric quadriceps exercises and straight-leg raises are encouraged as soon as pain subsides. Range of motion may be delayed in any situation in which the soft tissue envelope, wound closure, or fracture fixation is tenuous.
The most common method of repair we use employs two grasping stitches passed through three longitudinal drill holes in the patella and tied over bone bridges. To begin, the edges of the quadriceps tendon are sharply debrided of grossly degenerated tissue providing a fresh surface to approximate to the patella. Absorbable sutures are placed into the medial and lateral retinacular tissues, but left untied until after the tendon repair has been completed. Two heavy nonabsorbable sutures (No. 5 Ticron or Fiberwire) are placed using a running Kessler or Krackow configuration leaving four strands of suture at the distal quadriceps stump. A trough is then created in the superior patella using a small burr or rongeur.
Three 2-mm drill holes are made parallel to each other along the longitudinal axis of the patella from superior to inferior. A Hewson suture passer is passed from the proximal patella through the drill hole. A No. 2 nylon suture is looped and placed into the suture passer which is then pulled out proximally. The nylon suture is used as a shuttle or relay to pass the tendon sutures through the bone tunnels. The two central sutures are passed through the middle drill hole and retrieved at the inferior margin of the patella. The two remaining sutures are passed in a similar fashion through each of the peripheral drill holes and retrieved distally. Each of the central strands is passed under the patellar tendon and retrieved with its match so that the knots when tied will lie against the patella and not on top of the tendon. The sutures are tied with the knee in full extension. A drain is placed in the joint at this time as it can still be accessed through the retinacular defect. The retinacular sutures are then tied. If used, the tourniquet is deflated, and hemostasis is obtained. The hip is flexed and the knee is allowed to bend passively into flexion. A passive range of motion from 0 to 90 degrees is ideal. Patellar tracking and tension on the repair are also assessed. Finally, the repair is reinforced with 0 nonabsorbable sutures. The wound is closed with absorbable suture and the skin with nylon suture.
A straight midline incision is made from the midpatella to the tibial tubercle. Full-thickness skin flaps are created to expose the ruptured tendon and retinacular tissue. The edges of the patellar tendon are sharply debrided of grossly degenerated tissue providing a fresh surface to approximate to the patella. If there are small loose bone fragments they can be excised. The extent of the medial and lateral retinacular tears must be defined. These tissues are sutured but not tied with No. 1 nonabsorbable suture (Ethibond). Two No. 5 nonabsorbable sutures (Ticron, Fiberwire) are woven in a running Bunnell stitch resulting in one medial and one lateral suture strand and two central strands. A trough is created in the inferior patella with a small burr or rongeur to obtain a fresh cancellous bed to allow tendon–to–bone healing.
Three 2-mm drill holes are made parallel to each other along the longitudinal axis of the patella from inferior to superior. A Hewson suture passer is passed from the distal patella through the drill hole. A No. 2 nylon suture is looped and placed into the suture passer, which is then pulled out distally. This technique shuttles the nylon suture through the hole so that the core tendon sutures can be passed easily and retrieved proximal to the patella. The two central sutures are passed through the middle drill hole and retrieved at the superior margin of the patella. The two peripheral sutures are each passed through a drill hole in a similar manner. Each of the central strands is then passed under the quadriceps tendon so that the knots when tied will lie close to the patella and not on top of the quadriceps tendon. Tension is applied to the sutures which are clamped but not tied. A lateral radiograph is obtained to assess the patellar height in relation to Blumensaat’s line and in comparison to the contralateral knee. Suture tension can be increased or decreased to control the patellar tendon length. The sutures are then tied. A deep drain is placed and the retinacular tissue sutures are tied. Reinforcement is often necessary with a patellar tendon repair to counteract the force of the quadriceps muscle contraction. A transverse 2.5-mm drill hole is made 1 cm posterior to the tibial tubercle. An 18-gauge wire is passed through the hole, brought proximally, and passed under the quadriceps tendon close to the superior border of the patella and twisted until it is tight. The reinforcement wire is tightened with the knee in some flexion in order to avoid shortening the tendon. The knee is flexed to 90 degrees to test the integrity of the repair. The patellar tendon suture line is then reinforced with absorbable sutures. The wound is closed in layers and a well-padded dressing is applied. A hinged knee brace is applied with the knee in full extension. Active flexion and passive extension are begun by 2 weeks postoperatively starting at 0 to 45 degrees and advancing 20 to 30 degrees every 2 weeks. Active knee extension is permitted at 6 weeks. Weight bearing is allowed immediately and crutches are used for at least 6 weeks. The hinged knee brace and crutches are discontinued when the patient is able to ambulate with good quadriceps control.
Tibial tubercle avulsions represent an uncommon variant of extensor mechanism injuries. Treatment concepts are similar to those employed in the treatment of distal pole patellar avulsions. If the bone fragment is large enough, internal fixation with 3.5-mm or 4.5-mm screws should be performed with the addition of a stress-relieving cerclage wire to protect the repair. If the tubercle fragment is too small for screw fixation, the tendon should be reapproximated to the proximal tibia through bone tunnels similar to the treatment used in other tendon avulsion injuries.
Patients sustaining a first-time patellar dislocation are treated with closed reduction and immobilization of the knee in extension for 1 to 2 weeks. Radiographs are obtained after reduction. Patients are permitted to fully weight bear in the immobilizer. If a large hemarthrosis is present or plain-film evidence of osteochondral fracture exists, an MRI scan is obtained. At 1 to 2 weeks, the patient is transitioned to a patellar stabilizing brace and begins therapy focusing on range of motion and quadriceps, especially VMO strengthening. Patients may return to athletics when range of motion and strength approach the uninjured side.