Trauma About the Knee, Tibia, and Foot



Trauma About the Knee, Tibia, and Foot


Mininder S. Kocher, MD, MPH

Kevin G. Shea, MD1


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Knee


PATELLA SLEEVE FRACTURES

In this injury unique to children, the extreme distal or proximal pole of the patella, together with a significant sleeve of articular cartilage, periosteum, and retinaculum is pulled off the remaining main body of the patella (Fig. 10-1). The easiest pitfall in this fracture is to miss it at initial presentation (Fig. 10-2), as there may only be a hint of ossified bone on initial radiographs. The clinical picture at presentation usually includes a palpable defect at the affected patella pole and an inability to fully extend the knee or perform a straight leg raise.


Any significant displacement should be operatively fixed, as there may be significant articular cartilage avulsion not appreciated on plain radiographs. If displacement is questionable, flexion/extension lateral films should be made in superior and inferior sleeve avulsion fractures to assess intrinsic soft tissue stability. Widening of the fracture gap with lateral radiographs in flexion usually indicates a need for surgical stabilization.1 MRI can be useful as a small bony fragment of the inferior pole on X-ray may include a large patellar articular cartilage component appreciate on MRI.


During surgery, retinacular repair is performed. If necessary, sutures securing the patella tendon or quadriceps tendon may be passed through drill holes through the patella for fixation. A nonoperative, or inadequate operative repair may progress to further displacement during healing or rehabilitation (Fig. 10-3). A patella sleeve fracture should not be confused with Sinding-Johansson-Larsen disease, which is a chronic overuse injury that may be thought of as an Osgood-Schlatter (OGS) disease of the other side of the patella tendon.






Figure 10-1 Sleeve fracture of the patella. A: A small segment of the distal pole of the patella is avulsed with a relatively large portion of the articular surface. B: On lateral view, the small osseous portion of the displaced fragment is visible, but the cartilaginous portion is not seen. C: Healed sleeve fracture after open reduction and internal fixation. (Reprinted with permission from Sponseller PD, Stanitski CL. Fractures and dislocations about the knee. In: Beaty JH, Kasser JR, eds. Rockwood & Wilkins’ Fractures in Children. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2001:981.)







Figure 10-2 A: Patella sleeve fracture of the superior pole. This was missed in the emergency department. B: Two weeks later, ossification makes fracture more visible on radiographs. Surgical reconstruction at this stage is more involved.






Figure 10-3 A: Six-week postoperative radiograph, lateral view, demonstrating migration of fracture fragment. B: Three-month postoperative radiograph of the same patient. C: One year postoperative radiograph of the same patient.





DISTAL FEMORAL PHYSEAL FRACTURES

The first pitfall in these fractures is missing the diagnosis. In the mature skeleton, ligaments usually fail before bone when a bending stress is applied across the knee joint, so following a severe valgus stress across the knee a medial collateral ligament (MCL) injury may occur (Fig. 10-4). As the collateral ligaments originate on the epiphysis, in an immature skeleton, the physis will fail in tension and the knee will fall into valgus though a Salter I or II fracture (Fig. 10-5). A Salter I fracture may be non-displaced and not radiographically obvious. If suspicious of a type I distal femoral undisplaced fracture, the width of the physis is often greater than the contralateral physis on X-ray. Clinically, there should be tenderness about the physis, which is near the superior pole of the patella on either side of the knee, and the knee may be unstable to valgus or varus stress. A stress view radiograph or MRI can confirm the diagnosis; however, the need for either test has been questioned as the initial treatment for both an MCL injury and a nondisplaced distal femoral Salter I fracture is immobilization. Repeat radiographic and clinical examination at 10 to 14 days should help clarify the diagnosis.2 It is important to make a diagnosis at some point, because Salter fractures about the knee require follow-up for evaluation of possible growth plate injury.

The most common sequelae to distal femoral physeal injuries is growth disturbance, either total arrest which leads to shortening, or partial arrest leading to angular deformity. Angular deformity following distal femoral physeal injury is reported in 18% to 51% of recent series.3,4,5,6 Growth injuries usually occur at the time of injury, and not a result of mismanagement. Stay out of trouble, and depositions, by informing parents before a growth disturbance occurs that the chances are nearly 50% this problem will occur in their child, and that surgery,
including stopping the growth of the “normal” side may be needed in the future. While these injuries cannot be prevented, one thing we can do is to follow children with physeal injuries about the knee for at least 1 year closely. A growth disturbance which is identified early may be treated with either a contralateral epiphysiodesis (near the end of growth) or a Langensköld procedure. An angular deformity recognized late may require an osteotomy. An MRI with sequences chosen to highlight cartilage can aid in the early diagnosis of a physeal bar formation. One mechanism of injury that lies in wait to trap an unsuspecting orthopaedic surgeon is an unrecognized physeal injury in association with nonphyseal fractures in the femur or tibia. Hresko et al reported on seven children who had a physeal arrest about the knee in association with nonphyseal fractures in the lower extremity.7






Figure 10-4 Injury pattern with closed growth plates. In the mature skeleton, ligaments usually fail before bone when a bending stress is applied across the knee joint, so following a severe valgus stress across the knee a medial collateral ligament (MCL) injury may occur. Black arrow is direction of force.






Figure 10-5 Injury pattern with open growth plates. As the collateral ligaments originate on the epiphysis, in an immature skeleton, the physis will fail in tension and the knee will fall into valgus, though a Salter I or II fracture. Black arrow is direction of force.

In terms of treatment, one should strive for anatomic reduction of these fractures. Series have reported rates of 43% to 70% of distal femoral fractures treated without internal fixation have displaced.8,9 Unless a fracture is truly nondisplaced and stable, stay out of trouble by providing internal fixation. To avoid further injury to the physis, reduction should be 90% traction and 10% manipulation, preferably in the operating room with maximal relaxation. Salter I fractures may be stabilized by smooth Kirschner wires (K-wires). Wires should not cross at the fracture, but one should attempt to have the K-wires maximally separated at the fracture line. Clinical experience and animal studies have demonstrated that crossing the physis with smooth K-wires of the size commonly used should not cause a growth disturbance.10 Anteriorly displaced Salter I fractures deserve special mention. Previous texts have recommended closed reduction and casting with the knee in a flexed position; however, this treatment may lead to knee stiffness and makes evaluation of frontal plane alignment quite difficult. Stay out of trouble by pinning these fractures and providing immobilization in near full extension. Of course the knee should not be immobilized in extension until the fracture has been reduced, or vascular occlusion or peroneal nerve injury may result.

A potential pitfall using intra-articular K-wires is the possibility of a superficial pin tract infection progressing to a septic knee joint. Early fracture healing usually allows these pins to be pulled at 3 or 4 weeks, which helps prevent this complication. Continued protected immobilization is still indicated until clinical healing. In thin children, pins may be brought out of the skin proximal to the fracture site, and thus not be intra-articular. Salter II fractures may often be closed reduced and fixed with cannulated screws in compression across the metaphyseal fragment.


Regardless of the local stability of fracture fixation about the distal femur or proximal tibia, immobilize the entire leg to prevent the long lever arms of the tibia and femur from displacing the fracture. Series report 20% loss of reduction of these fractures. In children with short and/or wide thighs, consider extending immobilization proximally to include the waist.

Associated ligament injuries may occur at time of injury and should be evaluated following fracture fixation and again following fracture healing. Knee stiffness can be expected in about 25% of patients, so the surgeon should warn parents ahead of time, as well as consider early physical therapy. Fortunately, while peroneal nerve and popliteal artery injuries may occur with distal femoral physeal fractures, they are not common. Dr. Chad Price reminds us of the “satisfaction of search” pitfall.11 This describes a situation in which the detection of one radiographic abnormality interferes with that of others—once one fracture is found, you are satisfied and stop looking (Fig. 10-6).








Figure 10-6 AP radiograph of a 5-year-old boy in a stroller who was struck by a car. The Salter I fracture of the distal femoral physis was not recognized, and the child was initially treated with a short leg cast. This is an example of falling into the trap of “satisfaction of search.” When the first fracture is noted, human nature is to feel satisfied and not view the remainder of the radiograph with necessary diligence.


DISTAL FEMORAL METAPHYSEAL FRACTURE

This injury is mentioned only to avoid the pitfall of trying to treat a displaced fracture with casting without fixation. The gastrocnemius muscle attaches to the distal femur, thus pulling the distal femur into flexion. This tempts the surgeon to cast reduce and cast this fracture in knee flexion. However, if the knee is casted in flexion, exact alignment of varus/valgus positioning is nearly impossible to verify. Unfortunately, once the knee is extended after fracture healing, the full extent of varus or valgus malalignment becomes apparent. Avoid this complication by providing fixation, often with K-wires, cannulated screws, flexible IM nails, or an external fixator for displaced distal femoral metaphyseal fractures.


Tibia

See Chapter 14, The Pediatric Athlete, for tibial spine fractures.


TIBIAL TUBERCLE FRACTURES

Tibial tubercle fractures occur almost exclusively in boys, and usually during jumping sports such as basketball. This fracture occurs along the apophysis deep to the tibial tubercle, and should not be confused with Osgood-Schlatter disease (Table 10-1), although preexisting OGS symptoms may be present.

This fracture tends to occur in adolescents near the end of growth, so growth disturbance is usually not a problem. The fracture may extend into the joint (type III), in which case anatomic reduction is needed and associated intra-articular injuries such as meniscus or ligamentous injuries should be searched for. Beware that some active knee extension may still be present through retinacular fibers, so active knee extension does not rule out a tibial tubercle fracture. Type IV fractures that occur up the apophysis, across the physis, and then down the posterior metaphysis are particularly unstable and usually require surgical screw stabilization12 (Fig. 10-7).

Tibial tubercle fractures may involve extensive soft tissue avulsion requiring repair as well Sleeve avulsion fractures of the tibial tuberosity extending over the anterior metaphyseal area of the tibia has been recently described.13 These injuries are similar to patellar sleeve fractures, in that initial radiographs may show no more than small subchondral fragments of bone. Davidson and Letts report fixation of the type V sleeve avulsion fracture is challenging because of a lack of a large bony fragment.13 They recommend fixation with small-diameter screws and heavy nonabsorbable sutures between the intact periosteum or bone and the large avulsed segment of periosteum.


The most common complication following fracture healing is prominent hardware requiring removal. The use of multiple smaller screws (4.5 mm instead of 7.3 mm) may help minimize this complication. The most serious complication of this fracture is compartment syndrome.14,15 Because this fracture is associated with relatively low-energy trauma, compartment syndrome may not be on the radar screen of the unknowing surgeon. Compartment syndrome occurs presumably
because of tearing of anterior tibial recurrent vessels, which fan out at the tubercle but retract into the anterior compartment when torn (Fig. 10-8). Close monitoring is necessary for patients treated nonoperatively, and careful inspection, possibly with prophylactic anterior fasciotomy, is recommended for patients treated operatively.






TABLE 10-1 Do Not Confuse a Tibial Tubercle Fracture With Osgood-Schlatter Disease

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Jan 30, 2021 | Posted by in ORTHOPEDIC | Comments Off on Trauma About the Knee, Tibia, and Foot
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