Avulsion fractures of the intercondylar spine or anterior cruciate ligament of the tibia are not uncommon in clinical practice and are mostly caused by low-velocity violence during knee hyperextension and external rotation of the femur under axial loading.
Meyers and McKeever invented a very clinically significant imaging staging system, which is divided into 3 types: type I for nondisplaced fractures, type II for displaced fractures at the site, still connected to the intercondylar spine posteriorly, and type III for completely displaced fractures. And Zaricznyj added to them type IV as a comminuted avulsion fracture block.
Both type I and type II fractures can be healed by conservative treatment, but type II fractures can undergo re-displacement and malunion after conservative treatment. Types III and IV must be treated surgically because conservative treatment is prone to complications such as nonunion or malunion, resulting in limited knee extension and flexion and impaired ambulation.
Pandey et al. described a transarthroscopic surgical approach for the treatment of tibial intercondylar spine type II-IV fractures with an intravenous cannula needle and a high-strength nonabsorbable wire, published in Techniques in Orthopaedics, 2013.
Surgical technique
After inflating the tourniquet, a diagnostic arthroscopic procedure is performed via a standard anterolateral approach. The joint and fracture surface are cleared of hematoma, and constant irrigation is performed to remove microscopic fragments of the fracture mass in order to fully expose the joint and fracture site.
Next, cartilage and meniscal injuries are thoroughly evaluated and the injury is promptly addressed. Arthroscopic assessment of the intercondylar spine avulsion fracture is performed, along with staging of the fracture.
The transverse intermeniscal ligament (TIL) is often embedded between the fracture fragment and the intercondylar spine defect and can interfere with the repositioning of the fracture fragment, which needs to be separated by arthroscopic lens or suture traction, and then an attempt is made to reposition the fracture site by applying pressure to the fracture fragment with an anterior cruciate ligament (AML) fixture.
A 1-inch long incision is then made parallel to the tibial tuberosity and is separated down to the subcutaneous fascia. The tip of the AML jig is then placed on the medial edge of the fracture tear defect, and a tibial channel is made with a 1.5-mm kerf pin immediately adjacent to the tip of the jig and left in place. Similarly, a tibial channel was also punched into the lateral edge of the defect with a Kirschner needle (Figure 1A).
A 14G venous cannula needle is snapped with a 1-0 PDS suture to create a loop (Figure 1B)). The trocar needle with the coil is inserted into each of the tibial channels while the Kirschner needle is removed (Figure 1C). When the trocar tip appears at the microscopic articular surface bone defect, the folded coil is advanced, allowing the trocar pin to be held in place. This allows the fracture block to be reset and the repositioned position to be maintained with clamps.
Figure 1: A, two kerf pins inside and outside the avulsion fracture defect; B, intravenous cannula pin with folded suture, the protrusion is due to the elastic effect of the suture itself; C, intravenous cannula pin replacing the kerf pin position. The small picture on the right shows an in vitro view of the knee joint.
An 18G intravenous cannula needle with a 1-0 suture then enters the joint cavity via the most medial aspect of the superior aspect of the medial meniscus, with the cannula needle tip passing through the medial coil (Figure 2A). It is then inserted posteriorly at the point where the ACL joins the fracture block where the tear occurred and is threaded out laterally.
Once the trocar needle is seen, the suture is pushed forward at the tip of the trocar needle. The suture is grasped with the arthroscopic grasp after exiting the needle and then passed through the lateral suture loop before exiting at the anterolateral incision (Figure 2B). The above steps are repeated, but this time through the anterior aspect of the anterior cruciate ligament (Figure 2C). Figure 3 shows a diagram of the intravenous cannula needle passing through the anterior cruciate ligament.
Figure 2: A, the 18G intravenous cannula needle enters percutaneously by the medial meniscus and passes through the medial coil; B, the cannula needle passes through the medial coil, then through the anterior cruciate ligament, then through the lateral coil and out of the knee; C, the two PDS sutures pass anteriorly and posteriorly through the anterior cruciate ligament and come out through the anterolateral 5.5 mm entrance of the knee.
Figure 3: Schematic diagram of an intravenous cannula needle passing through the anterior cruciate ligament.
Two more non-absorbable Ultrabraid sutures are used to replace each of the initial two PDS sutures by a repeated threading technique (Figure 4A). At this point, the trocar needle has exited the tibial channel and the PDS coils are subsequently threaded out of the body (Figure 4B). This allows tension to be created by pulling on the UB sutures to reposition the ACL, thus helping to reset the fracture fragment into the defect (Figure 4C).
Figure 4: A, the PDS suture is replaced by the UB suture; B, as the PDS suture is removed from the tibial tunnel, the UB suture is pulled out of the body; C, the fracture fragment is satisfactorily repositioned and the UB suture tied to the suture button is visible in the upper right inset.
After the fracture is repositioned, the UB sutures are tied in knots to the tibial bridge or suture button between the tibial channels, respectively, which can be accomplished by bending the knee at 30° and pushing back on the tibia if the bridge is too narrow.
Finally, after arthroscopic exploration to confirm that the fracture has been repositioned and that the anterior cross is in proper tension, the knee is extended to observe for intercondylar fossa impingement signs.
Preoperative lateral radiographs of the knee suggested a type III intercondylar spine avulsion fracture (Figure 5A), and postoperative plain radiographs showed that the fracture site had been satisfactorily repositioned (Figure 5B).
Figure 5: A, Preoperative lateral radiograph of the knee suggesting a type III intercondylar spine avulsion fracture (arrow); B, postoperative lateral plain radiograph showing that the fracture site was satisfactorily repositioned.
Postoperatively, the knee was immobilized in an extension brace for 2 weeks. On the first postoperative day, non-weight-bearing walking with crutches was possible, and static contraction of the quadriceps muscle was also possible. Moderate knee motion was allowed at week 3, partial weight-bearing at week 4, and full weight-bearing by week 8.
Eight patients with avulsion fractures of the intercondylar spine of the tibia were included in the study, including seven Meyer type III fractures and one Meyer type IV fracture. The mean follow-up time was 17.25 months (12-22), and all patients achieved fracture healing at 12 months of follow-up. The mean Lysholm score at follow-up was 98.12, with seven patients having an IKDC grade of A and the remaining one having a grade of B. None of the patients had any impairment in knee extension and were able to perform normal pre-injury activities.
In addition, the authors concluded that this technique is also suitable for treating intercondylar spine avulsion fractures in adolescents with immature epiphyses because the diameter of the tibial channel is only 1.5 mm and does not damage the growth plate of the bone.