Bioabsorbable nails effective at repairing full-thickness osteoarticular knee defects

At latest follow-up, all patients had equal range of motion in both knees, and none had evidence of tenderness or effusion.

Biabsorbable poly-L-lactic acid nails may be an effective option for arthroscopically repairing full-thickness osteoarticular defects that feature intact, partially detached pieces of cartilage, according to a small study by researchers in New York.

Joshua S. Dines, MD, and colleagues evaluated the functional and radiographic outcomes for nine patients treated for osteochondral lesions involving the femoral condyle. These patients averaged 18 years of age, ranging from 12 years to 39 years. Eight patients had osteochondritis dissecans and one had an osteochondral fracture, according to the study, published in Arthroscopy.

"In our series, surgery was indicated for patients with a documented unstable lesion or those who had documented worsening of the lesion or symptoms despite nonoperative treatment," the authors wrote.

Using the Dipaola MRI staging classification, five cases were classified as stage II lesions and four as stage III lesions preoperatively. At surgery, lesions averaged 2 cm² and surface area averaged 3.9 cm².

In all cases, the surgeon used a poly-L-lactic acid bioabsorbable nail (SmartNail, ConMed Linvatech) for fixation and implanted an average of 4.1 nails, ranging from two nails to 10 nails.

In five patients with a partially detached lesion, the surgeon used either an arthroscopic shaver or drill to create a bleeding bony bed before fixing the fragment. The remaining four patients had lesions that were classified as having minimal separation with intact articular cartilage, according to the study.

"In these patients, there was no preparation of the underlying subchondral bone, and the lesions were pinned in situ," the authors wrote.

The bioabsorbable nails were inserted through holes drilled into the fragments and solid bone, completely penetrating the cartilage surface.

All patients remained non-weight-bearing for at least 6 weeks after surgery. Also, during the first 2 weeks postop, range of motion was protected from 0° to 30°, and then advanced over the following 4 weeks to 90°, according to the study.

Follow-up averaged 32.7 months.

"At the most recent clinical follow-up, all patients were satisfied with the procedure and would undergo the surgery again," the authors noted. "Range of motion was equal in both knees in all patients. No patient had evidence of tenderness or effusion on examination, and no patient complained of mechanical symptoms."

Lysholm knee scores averaged 94 points and were judged as excellent in seven patients, good in one and fair in one.

"All patients returned to their previous activities at a mean of 5 months after surgery," the authors noted.

Radiographic evaluations at 3 months follow-up showed fragment incorporation in all cases. MRIs performed at 5.3 months mean follow-up showed that the fragments had healed in seven patients. In the other two patients, MRIs showed "that the osteochondral lesion and overlying cartilage were of questionable integrity," they reported.

No patients showed evidence of a foreign body reaction, including synovitis or effusion within the joint.

For more information:
Dines JS, Fealy S, Potter HG, Warren RF. Outcomes of osteochondral lesions of the knee repaired with a bioabsorbable device. Arthroscopy. 2008;24:62-68.