Osteochondral Fragment Repair Using Knotless All-Suture Anchor Technique Within Patellofemoral Joint

Video Transcript

Background

Hello, today we will be presenting a case of a knotless all-suture anchor technique for the repair of an osteochondral fragment in the patellofemoral joint. We will give a brief overview of patellar dislocation and osteochondral injuries, as well as typical findings on physical examination. We will discuss various treatment options. Then, we will present a case and surgical technique, highlighting positioning, approach, and our repair technique. We outline a postoperative rehabilitation protocol as well as discuss reported outcomes in the literature.

Patellar dislocation accounts for 2% to 3% of knee injuries, affecting roughly 14 per 100,000 people. ⁵ After a single lateral patellar dislocation, 43% of patients will experience a chondral injury, with 25% having a pure chondral lesion and 18% suffering an osteochondral injury. ⁵ The most common site is the medial facet of the patella, followed by the central facet, and finally the lateral femoral condyle. ²

On physical examination, you will typically encounter a large knee effusion for an acute presentation. ⁴ Other common examination findings include tenderness to palpation over the medial retinaculum, a positive patellar apprehension test where passive distal and lateral translation of the patella at 20° of knee flexion results in guarding and a subjective sense of apprehension, and finally increased lateral patellar translation compared with the contralateral side. ⁶

Generally, fragments amenable to fixation should be fixed. ³ Multiple techniques have been described, from screws of different materials to suture-based techniques.^1,8 Those lesions not amenable to fixation can be treated with other described cartilage restoration procedures, depending on the size and depth of the lesion. ⁷

Indications

Our patient is a 14-year-old male who presented with an acute left knee injury. He was playing basketball 2 days prior and twisted his leg upon landing from a jump. He had no relevant past medical or surgical history. He weighed 46 kg and was 1.62 m tall. On examination, he walked with an antalgic gait and stood with neutral alignment. He had moderate left knee swelling with 5° to 120° of knee flexion, limited by pain. He was tender to palpation along the medial patella. He had full strength in flexion and extension and was able to perform a straight-leg raise. He demonstrated a stable cruciate and collateral ligamentous examination. He had a positive patellar apprehension test and a positive J sign. His patella translated 2 of 4 quadrants with lateral pressure, with a soft end point, and a quadriceps angle of 14°. He was grossly neurovascularly intact and was currently a high school student.

In the clinic, radiographs revealed a moderate effusion and irregularity along the medial patellar facet, suggestive of injury, with a normal Insall-Salvati ratio of 1.17 and neutral standing alignment. A magnetic resonance imaging (MRI) was obtained, which showed bony contusions at the lateral femoral condyle and the inferomedial aspect of the patella in a pattern suggesting sequelae of a patellar dislocation-relocation injury, as well as a normal tibial tuberosity-trochlear groove distance measuring 9.1 mm.

Our patient was diagnosed with a first-time patellar dislocation and treated conservatively with a patellar stabilizing brace and a course of physical therapy. At his 2-month visit, his pain was much improved, and he began weaning out of his brace. At 3 months, the patient returned to sports (RTS) after clearing physical therapy's RTS protocol via Biodex testing. Unfortunately, the patient returned at 4 months after landing awkwardly while playing volleyball and reinjuring his left knee.

Another MRI was obtained, demonstrating a large osteochondral fragment and associated defect at the lateral femoral condyle, as well as a bone marrow edema pattern consistent with a repeat patellar dislocation. Here are the T2 axial cuts of the knee demonstrating the large osteochondral fragment floating free within the patellofemoral joint space. Here are the sagittal and coronal T1 and T2 sequences again, demonstrating the large osteochondral fragment as well as the lateral femoral chondral defect.

Technique Description

This patient was indicated for diagnostic knee arthroscopy and loose-body removal; open reduction and internal fixation of his large osteochondral fragments; and medial patellofemoral ligament reconstruction to stabilize his patella and prevent further dislocations and cartilage injury. The procedure was performed in the supine position with a valgus stress post. We had standard arthroscopic equipment available as well as retractors, curettes, Kirschner wires, cystic forceps, 18-gauge hypodermic needles, and closing sutures. Our implants included all-suture knotless suture anchors with a No. 2 nonabsorbable suture and a semitendinosus allograft. Also, 3-mm bioabsorbable headless compression screws were available if there was sufficient underlying bone to attempt screw fixation.

To begin, we performed diagnostic arthroscopy of the knee, followed by loose-body removal through standard anterolateral and anteromedial portals. Intraoperative arthroscopic pictures were taken demonstrating the large osteochondral fragment and associated lateral femoral condyle cartilage defect, which measured 25 × 28 mm. There was minimal underlying bone on the fragment, making it unsuitable for screw fixation. For osteochondral fixation, we utilized a lateral parapatellar approach as the lesion was laterally based. Had the lesion been medially based, a medial parapatellar approach would be best to perform the repair. A 5-cm incision was made overlying the defect for the lateral parapatellar approach.

We next prepared our osteochondral fragment and the lateral femoral condyle defect for repair. Fibrous tissue was first removed using a curette. We then roughened the repair site using a curette or rasp down to the level of healthy bleeding subchondral bone to encourage healing. Substantial time was spent trimming both the defect and the fragment to a stable rim with a matching shape, as the fragment will swell after being loose in the synovial fluid. Finally, a sample of cartilage was sent for tissue banking in case a matrix autologous chondrocyte implantation procedure would be needed in the future.

Next, the fragment was positioned within the donor site, and its fit was confirmed. The fragment was removed, and four 1.8-mm knotless all-suture anchors were placed around the periphery of the defect. When placing our anchors, we attempt to minimize horizontally placed sutures relative to the joint surface, as we believe this increases wear on the cartilage. The fragment was placed back into the defect, and the fixation sutures were passed over the chondral fragment, 2 from inferior to superior and 1 from inferolateral to superomedial. They were then sequentially tightened. The knee was ranged from flexion to extension, and the repaired lesion remained stable. Sutures were cut. The edges of the fragment were reduced, stabilized, and sealed with a thin layer of fibrin glue. Returning to our intraoperative case, these are our patient's arthroscopic photos demonstrating a stable repair. Finally, a medial patellofemoral complex reconstruction was performed to stabilize the patella from further dislocations and to protect the chondral repair.

Results

Below is the postoperative protocol used for this patient. Notably, the patient remains nonweightbearing for at least 6 weeks, and range of motion is advanced as the patient progresses with physical therapy. By 10 weeks, the hinged knee brace is removed while they continue to focus on strengthening, muscular control, and sport-specific activities.

There is sparse literature on outcomes of osteochondral fixation, especially with newer techniques such as bioabsorbable materials and suture anchors. A retrospective case series led by Wilson et al ¹⁰ used suture bridge fixation on 40 knees with osteochondral lesions secondary to trauma and osteochondritis dissecans. Their mean patient age was 15 years. They used absorbable suture for all their traumatic osteochondral lesions and nonabsorbable suture for some of their osteochondritis dissecans lesions. An example construct is shown here. Follow-up imaging showed full healing in the majority of patients. There were 2 reoperations for repeat marginal chondroplasty on an otherwise stable lesion and reoperation for initially untreated patellar instability, with no reoperations for failure or revision of the suture-bridge construct.

Additionally, Scanlon et al ⁹ conducted a retrospective case series of 19 patients with 16-month follow-up that showed high patient satisfaction after treatment of osteochondral lesions with a bioabsorbable screw. Their patients were made partial weightbearing for 6 weeks. Four of these patients returned to the operating room for the complications of superficial surgical site infection, knee stiffness, recurrent instability, and symptomatic hardware.

Discussion/Conclusion

Osteochondral fragment fractures are a common sequela of patellar dislocation, occurring in 43% of cases. ⁵ Numerous methods exist to fix osteochondral fragments, with newer methods utilizing bioabsorbable screws, anchors, and sutures gaining popularity. Early results show promising outcomes and union rates with suture-bridging techniques.