Osteochondral Fracture Associated With Patellar Dislocation: Surgical Treatment

Abstract

Background:

Patellar dislocation can be associated with osteochondral fracture with fragments from the patella, femur, or both. These fragments may be excised or fixed.

Indication:

An associated osteochondral fracture is the main indication to operate in cases of first-time patellar dislocation.

Technique Description:

Using an arthrotomy, the osteochondral fragment can be retrieved and fixed using headless screws. To stabilize the patella, the medial patellofemoral ligament (MPFL) can be either reconstructed with an autograft (gracilis tendon) or repaired (when avulsed from the patella).

Results:

Fixing an osteochondral fragment promptly can restore the articular surface, avoiding patellofemoral or femorotibial incongruence, which could lead to pain, swelling, poor function, and progression to osteoarthritis. There were good functional results at follow-up, and patients returned to sport.

Discussion/Conclusion:

We recommend that patients with osteochondral fractures that alter the joint congruity be treated surgically after the first episode of patellar dislocation. MPFL repair or reconstruction should be added during the same time as the surgery, with the latter being preferable.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This video demonstrates 2 cases of osteochondral fractures associated with first-time patellar dislocation. Both fragments, one from the medial facet of the patella and one from the lateral condyle, were large, locked the joint, and could have a negative impact on the future if not fixed in the acute context. This is the primary indication for surgery after a first episode of patellar dislocation.

Background

This investigation was conducted at Fundación Valle del Lili Hospital in Cali, Colombia. The authors report no conflicts of interest. The video content includes the rationale for surgically treating these patients, case presentations, a demonstration of the technique to fix the osteochondral fracture and manage the medial patellofemoral ligament, the rehabilitation protocol, tips and tricks, and conclusions.

Indications

After having a first episode of patellofemoral dislocation, most patients may be treated nonoperatively. ¹⁰ There are a few indications for primary surgery, and having an osteochondral fracture or loose body that requires internal fixation or removal is the principal indication. ⁵ Usually, patients are treated surgically after recurrent dislocations. Some fragments are small and could be treated without surgery or with surgical resection. It is less frequent to have a fracture that involves the whole medial facet of the patella or a weightbearing area of the femur. When the osteochondral fragment is >1 cm, it is suggested to fix it to improve clinical outcomes. ¹

The first case is a 13-year-old female patient who fell in school, resulting in a first-time patellar dislocation. She required closed reduction at the emergency room, but after this, she continued to have pain associated with severe effusion, a locked knee, and severe patellar apprehension.

The initial radiographs showed patellar dislocation with an osteochondral fragment from the patella, which was confirmed with the radiograph after reduction of the dislocation. The magnetic resonance imaging (MRI) revealed that almost all the medial facets of the patella were fractured and loose in the knee joint.

Technique Description

Surgery was performed in the supine position. The knee was aspirated, obtaining lipohemarthrosis that should make the physician suspect an associated fracture. The anatomical landmarks were marked, establishing the position of the patella, the adductor tubercle, and the tibial tuberosity. The first incision was performed at the pes anserinus to extract the gracilis autograft that would be used to reconstruct the medial patellofemoral ligament (MPFL). It was mixed with 500 g of Vancomycin and 100 mL of normal saline. This was followed by a second incision, medial to the patella, that would expose it for the osteochondral fixation and the MPFL reconstruction (MPFLR). The medial facet fragment was found, extracted, and evaluated. Its size was about 30 mm in length and 20 mm in width. A 2.0 Steinmann wire was placed in the patella and used to invert it and visualize it better. The fragment was reduced, a Kirschner wire was used to keep the fragment in place, and a headless Accutrak 2.5-mm screw was placed to definitely fix the osteochondral fracture, as shown.

The adductor magnus tendon is identified, as it will be used as a sling for the reconstruction of the MPFL. The gracilis tendon is fixed into a tunnel socket 4.5 mm in diameter and 10 mm deep in the proximal third of the medial patella. The graft is sutured to the periosteum at the entrance of the tunnel with Vicryl 1. Then, the graft is passed through layer 2 of the medial retinaculum toward the adductor magnus tendon, where the graft goes around the adductor tendon as a sling and is pulled back to the patella through layer 2. The first bundle of the autograft is fixed to the adductor magnus tendon with Vicryl 1 suture at 40° of knee flexion. Patellar stability may be tested before fixing the second bundle. The second bundle of the gracilis autograft is fixed at 30° of knee flexion, with sutures into the anterior periosteum of the patella in a soft tissue tunnel. ⁸ The medial retinaculum and arthrotomy are now closed. Note that the adductor tendon sling is not the exact anatomic insertion site for the MPFL in the femur. Still, it is a good alternative, especially in patients with open physis, to avoid tunnels near the physis. Final stability is evaluated, and a soft bandage is applied.

One month later, the patient could walk without crutches, and the radiograph showed appropriate fixation of the osteochondral fracture. Range of motion did not progress from 100° of knee flexion 3 months after surgery; therefore, the patient was taken to the operating room to mobilize the knee under anesthesia. She continued to be well, with full range of motion, satisfactory radiographs, return to sport, and no pain 2 years after surgery.

The second case is a 12-year-old male patient, presenting with a first-time patellar dislocation in his left knee that occurred while playing soccer and required closed reduction at the hospital. The patient continued with pain, severe effusion, positive apprehension test, and a locked knee. Radiographs did not seem to show any fractures, but a computerized tomography scan and an MRI showed an osteochondral fracture. Initially, it seemed to be from the patella, but it was in fact from a weightbearing area of the lateral femoral condyle. An anterolateral approach to the knee was done to retrieve the osteochondral fragment and expose the lateral femoral condyle. This fragment was fixed with 2 headless Accutrak 2.5-mm screws, restoring the articular surface of the condyle. The medial patellofemoral ligament was avulsed from the patella, and it was repaired, reinserting it with a 2.8-mm titanium FASTak anchor to the medial side of the proximal third of the patella. The postoperative radiographs showed the appropriate position of implants. This patient was in partial weightbearing for 2 months, when he gained the full range of movement. At 3 months, he gradually returned to doing functional exercises.

Results

The postoperative rehabilitation includes immediate partial weightbearing with crutches and complete weightbearing after 4 to 8 weeks, depending on the place of the fracture; if it is a weightbearing zone, it would take 8 weeks. Patients use a knee brace in extension for 10 days and then begin to gain range of movement, trying to achieve 0° to 90° by week 4 and complete range of movement by week 8. Isometric strengthening is promoted from the first day. Return to noncontact sports is usually at 6 months, and contact sports after 12 months.

Potential complications and pitfalls include leaving the headless metallic screws superficial in the articular cartilage, which can lead to cartilage wear. Arthrofibrosis, which could be related to the length of time patients are immobilized, is why you should promote the regain of range of movement as soon as possible. Finally, if these metal screws are in a weightbearing area, they should be removed in a subsequent surgery, which would be an advantage for using biocomposite screws.

Discussion/Conclusion

Surgical treatment should be performed as soon as possible to avoid any additional damage to the osteochondral fragment that could affect its viability. Fixation of osteochondral fractures has shown better results than debridement.^3,4 We recommend routine MRI in patients with patellar dislocation to rule out osteochondral or chondral fractures. Arthroscopy can be useful in the diagnosis and decision-making process. Try to fix large fragments to restore the joint congruity. We recommend using 2 screws, but it will depend on the fragment size.

We recommend managing the MPFL at the same time if you are fixing an osteochondral fracture associated with a first-time patellar dislocation. In a recent consensus, 97% of surgeons would repair (30%) or reconstruct the MPFL at the same time, when operating on a first-time patellar dislocation with an osteochondral fracture associated. ⁹ A systematic review has shown that MPFL repair has less redislocation and knee pain than conservative treatment. ⁶ However, MPFLR has demonstrated less redislocation and better functional scores than repair, which is why it is the gold standard of treatment.^2,7