Femoral Avulsion of the Anterior Cruciate Ligament in a Multiligament Setting: A Unique Case

Abstract

Anterior cruciate ligament (ACL) femoral avulsions are a rare entity mainly seen in children. We describe a unique case of a bony ACL avulsion with a medial collateral ligament (MCL) and lateral meniscus (LM) tear in a 37-year-old patient who sustained a two-wheeler accident. The ACL femoral avulsion was fixed arthroscopically using a Knee Scorpion and a FiberTape fixed over a suture disc on the lateral cortex. The MCL was repaired with an internal brace using a FiberTape and two SwiveLocks and the torn LM was repaired using all-inside sutures. At 2 years of follow-up, the fragment was united, knee range of motion was 0° to 130°, and Knee Society Score was 98. This is the first case report of a femoral avulsion of the ACL combined with an MCL injury and a meniscus tear where all three were repaired with a unique technique and good results were obtained.

Avulsion injuries of the anterior cruciate ligament (ACL) are uncommonly encountered in clinical practice and can occur due to sporting or high-velocity trauma. In adults, ACL tears commonly occur in the mid-substance and less commonly avulses from its tibial attachment. Femoral avulsions of the ACL occur less frequently1). Most of the cases reported in the clinical literature occurred in the skeletally immature patients because of relatively elastic connective tissue and correspondingly weaker bony structures1). When osseous avulsions present early, it is possible to fix the fragment arthroscopically and facilitate bone to bone healing. Here, we report a unique case of an ACL avulsion at the femoral attachment combined with a medial collateral ligament (MCL) tear and a lateral meniscus (LM) tear in an adult. The ACL avulsion was fixed arthroscopically using sutures and a suture disc, the MCL underwent internal bracing and the LM was repaired.

Case Report

A 36-year-old man had a road traffic accident while riding a motorcycle. He had a collision with a pedestrian, which made him fall off his bike. He could not stand up after the accident because of pain and swelling of the right knee. He visited our clinic three days after injury with right knee pain, swelling and instability. Knee examination revealed grade 3 Lachman and anterior drawer tests with a soft endpoint and valgus stress test grade 3. The osseous avulsion was not apparent on a standard anteroposterior and lateral radiographs. On magnetic resonance imaging (MRI) and computed tomography (CT), the fragment could be seen distinctly on the axial section of the CT scan (Fig. 1A). The ACL was in continuity on an MRI but appeared lax (Fig. 1B). The MCL had a mid-substance tear (Fig. 1C). There was no evidence of a LM tear on MRI.

Fig. 1.

Magnetic resonance imaging (MRI) and computed tomography (CT) findings. (A) Axial CT showing bony avulsion of the anterior cruciate ligament (ACL). (B) Sagittal MRI showing the lax ACL. (C) Coronal MRI showing the torn medial collateral ligament.

1. Surgical Technique

1) Operative setup and patient positioning

The patient was positioned supine on the operative table under spinal anesthesia with the leg flexed to 90°. A tourniquet was used in surgery as there were no contraindications.

2) Portals

A high anterolateral viewing portal, a medial working portal for passport cannula (Arthrex, Naples, FL, USA) and a far medial drilling portal for the ACL footprint were created (Fig. 2).

Fig. 2.

Portals used for the technique include high anterolateral viewing portal, medial working portal, and far medial working portal.

3) Diagnostic arthroscopy

Diagnostic arthroscopy was carried out: a femoral avulsion of the ACL was observed (Fig. 3A); an undersurface LM tear was seen in the posterior horn in the red white zone (Fig. 3B); and there was a >10 mm opening of the medial compartment, suggesting an MCL tear (Fig. 3C).

Fig. 3.

Diagnostic arthroscopy findings. (A) Bony avulsion of the anterior cruciate ligament. (B) Lateral meniscus tear. (C) Medial compartment opening >10 mm.

4) Lateral meniscus repair

The tear was rasped with a meniscal rasp and repaired using a Knee Scorpion (Arthrex) loaded with 2-0 FiberWire (Arthrex) and taking a bite from the superior and inferior surfaces of the meniscus to approximate the tear. The two ends were then tied with a SMC knot. The three sutures were passed at 0.5-cm intervals (Fig. 4).

Fig. 4.

All-inside lateral meniscus repair.

5) ACL stump refixation

(1) Preparation of femoral footprint

The ACL footprint on the femur was identified and the center was drilled over a guidewire using a 4.5-mm drill bit with the knee in hyperflexion and an Ethibond (Ethicon, Somerville, NJ, USA) loop was passed through the tunnel (Fig. 5A–C). The ACL was then isolated from the posterior cruciate ligament by shaving the intervening fat pad (Fig. 5D). Through the medial portal, a Knee Scorpion loaded with 2-0 FiberWire was inserted to take a bite from the proximal 1/3 of the ACL (Fig. 5E). The 2-0 FiberWire acted as a suture shuttle to place the FiberTape (Arthrex) through the proximal part of the ACL stump (Fig. 5F); two equal arms of the FiberTape passed through the stump were delivered through the passport cannula. The FiberWire was again loaded to shuttle one end of the FiberTape through the bony fragment. Then, the FiberWire was passed through the other end of the bony fragment to shuttle the other end of the FiberTape such that a figure of eight configuration (crisscrossing) of the FiberTape on the ACL stump was established (Fig. 5G). The two ends of the FiberTape as well as the Ethibond loop were delivered through the passport cannula (Fig. 5H). The two ends of the FiberTape were then shuttled to the lateral cortex using the Ethibond loop.

Fig. 5.

Anterior cruciate ligament (ACL) refixation. The femoral footprint (A) was drilled with 4.5 mm drill bit (B). (C) The Ethibond (Ethicon) loop was delivered. (D) A shaver was used to create a space between the ACL and the posterior cruciate ligament. (E) Bite taken with a Knee Scorpion (Arthrex). (F) FiberTape (Arthrex) was passed through the stump. (G) Bites taken from the bony fragment. (H) Ethibond loop and FiberTape delivered through the passport cannula.

(2) MCL internal bracing

Internal Bracing of the MCL was done by loading a FiberTape on two SwiveLocks (Arthrex) that are inserted into the medial epicondyle and 2 cm below the joint line on the tibia, through 1-cm incisions under C-arm guidance at 30° of knee flexion after fixing the ACL over a suture disc.

6) Final fixation

An incision was made on the lateral aspect of the femur and the two ends of the FiberTape were tied over the suture disc (Fig. 6C). In arthroscopy, the ACL was in position and taut (Fig. 6A) and the medial compartment was opened <5 mm (Fig. 6B). In radiography, the suture disc was sitting on the bone (Fig. 6D).

Fig. 6.

Final fixation and arthroscopic findings. (A) Anterior cruciate ligament (ACL) after fixation. (B) Medial compartment opening <5 mm. (C) Lateral cortex femur fixation of the ACL. (D) Anteroposterior radiograph showing the suture disc.

2. Postoperative Rehabilitation

The patient was kept partial weight bearing from 6 weeks postoperatively, with knee bending allowed till 90° of flexion in a hinge knee brace. The brace was kept locked in extension while walking. Closed chain quadriceps strengthening exercises were begun from day 1 postoperatively. At 6 weeks after surgery, the brace was removed and the patient was allowed to walk full weight bearing with full knee flexion. Return to sports was advised at 6 months postoperatively.

CT scan and MRI were done at 3 months postoperatively, which revealed the ACL was in continuity and the bony fragment healed to the lateral aspect of the notch (Fig. 7). The LM had healed completely and the MCL had healed too on MRI. At 3 months and one year postoperatively, the knee was stable with a negative anterior drawer test and a negative valgus stress test. At one-year follow-up, the patient had a visual analogue scale of 0 and had returned to recreational sports.

Fig. 7.

Computed tomography (CT) and magnetic resonance imaging (MRI) findings at 1 year after surgery. (A) CT showing the healed bony fragment. (B) MRI of the anterior cruciate ligament in continuity.

Discussion

In children, epiphyseal chondral and osteochondral ACL avulsions are not uncommon because of relatively elastic connective tissue and correspondingly weaker bony structures1). Osseous avulsion of the ACL in the pediatric population occurs most commonly at the distal tibial attachment site1). However, in adults, the ACL tends to tear before osseous avulsion can occur1). Adult cadaveric models have demonstrated that under typical stressors, osseous avulsion of the ACL is less common than ligament disruption, and when osseous avulsion does occur, it occurs at the level of the tibial eminence1).

Most previously reported orthopedic articles were in the skeletally immature patient. However, there have been four case reports using different fixation techniques in the skeletally mature. Mechanism of injury varied from road traffic accidents to sporting injuries. Fixation of these avulsions varied from open to arthroscopic techniques using suspensory devices, K-wires and screws1–10). None of them, however, reported ACL avulsions associated with a meniscus tear and an MCL injury.

In most reported cases, femoral avulsion of the ACL was due to high-velocity trauma where the knee was subjected to flexion, internal rotation and varus stresses, resulting in an avulsion of the femoral attachment of the ACL with a posterior horn tear of the LM.

In our case, the patient had a high-velocity injury in the form of a road traffic accident while riding a two-wheeler. The patient reported the knee was in a flexed and externally rotated position immediately after the injury. We observed bruising on the medial aspect of the anteriorly extending knee at the initial visit of the patient at the clinic. The possible mechanism, considering the injuries the patient sustained, was a flexion external rotation injury to the knee, extending from the medial aspect to the lateral aspect of the knee, also affecting the MCL, ACL and LM subsequently. The avulsed fracture fragment was not apparent on the standard anteroposterior and lateral radiographs.

Axial CT sections demonstrated the bony avulsion and exhibited continuity of the fragment with the ACL. The MRI demonstrated the intact ACL with bone-marrow edema at the lateral femoral condylar donor site of avulsion. This indicates that despite exceedingly rare, osseous femoral avulsion injury of the ACL can occur in the adult.

Most of the previously reported cases used an open or mini open technique that could potentially lead to arthrofibrosis. Only two previous studies used arthroscopic fixation techniques: one using K-wires and the other using a TightRope (Arthrex). Using a K-wire intra-articularly necessitates an additional procedure for removal. The TightRope is a relatively expensive but effective surgical treatment device. This technique was unique in that it was performed on a case of multiligament injury of the knee with a repairable meniscus tear, where all three were repaired and healed in an adult. Table 1 summarizes previous case reports in terms of patient profile, injury patterns and fixation techniques for comparison with our case.

Table 1.

Review of Previously Reported Cases of ACL Femoral Avulsion and Comparison with the Present Case

Study	Age (yr)/sex	Injury mode	Fixation method	Operative findings
Shah et al.1)	47/F	Road traffic accident	4 mm cancellous screw fixation	Bony avulsion of ACL from femur
Bengtson and Giangarra2)	10/M	Sports induced	Mini open fixation with sutures (#2 MaxBraid)	Comminuted fragment
Wardle and Haddad3)	11/F	History of fall	Arthroscopic fixation with tight rope	Small size bony fragment
Langenhan et al.4)	14/F	Sports induced	Arthroscopically assisted K-wire fixation	Bony avulsion of ACL from femur
Eady et al.5)	7/F	Sports induced	Mini open fixation with sutures woven Bunnell fashion	Granulation tissue at bony fragment, debrided
Zabierek et al.6)	50/M	Scuba diving	Arthroscopically with screws	Bony avulsion
Tharakulphan et al.7)	32/M	Sports (soccer) injury	Arthroscopic suture loop fixation	No bony avulsion
Tohyama et al.8)	14/M	Sports induced	Fixed with Ethicon suture with button at lateral femur (mini open)	6–10 mm oval osteochondral fragment of bone
Kawate et al.9)	11/F	Sports induced	Arthroscopic fixation with Ethibond sutures	Osteochondral avulsion
Edwards et al.10)	11/F	Sports induced	Lateral parapatellar approach-modified Bunnell suture repair	Displaced avulsion fracture
Our study	36/M	Road traffic accident	Arthroscopic suture pull out technique	Osteochondral avulsion with lateral meniscus tear

ACL: anterior cruciate ligament.

The suture pull-out technique is a good option for arthroscopic fixation of a femoral-sided avulsion fracture of the ACL in skeletally mature patients when performed early after injury. This technique saves the natural ACL stump. The bone-to-bone healing yields a stronger construct than tendon-to-bone healing. Potential negatives include the point of fixation being away from the ACL insertion on the femur that may produce a bungee effect. Also, it is technically demanding to achieve anatomical reduction of the fragment, which may result in a loss of isometricity of the ligament.