Comparing Bipolar Knee Chondral Defect Treatments

A team of researchers from Rush University Medical Center in Chicago, Illinois, has found that regardless of tibial treatment, patients with bipolar chondral defects of the knee who are treated with femoral osteochondral allograft transplantation (OCA) will have clinically meaningful improvements in functional outcomes, as well as excellent graft survivorship.

Their work, “Does Treatment of the Tibia Matter in Bipolar Chondral Defects of the Knee? Clinical Outcomes with Greater Than 2 Years Follow-up,” appears in the April 2018 edition of Arthroscopy.

Charles P. Hannon, M.D. with the department of orthopedic surgery at Rush University Medical Center in Chicago, Illinois, and co-author on the study told OTW, “OCA is a successful treatment for large femoral defects with underlying subchondral bone loss or edema.”

“However, bipolar defects, where there are reciprocal lesions of both the tibia and femur are uniquely challenging.”

“The purpose of our study was twofold:

1. to determine how bipolar defects treated with femoral OCA, regardless of tibial treatment, compare to isolated femoral defects treated with OCA and
2. to investigate the treatment of bipolar tibiofemoral defects by comparing femoral OCA with debridement of the tibia to bipolar defects treated with femoral OCA and tibial microfracture.”

The authors wrote, “A series of patients with 2-year follow-up from March 2014 to September 2015 after femoral OCA for bipolar chondral defects was identified. Group 1 contained patients with tibial defects treated with debridement and group 2 contained patients with microfractured tibial defects. A third group (group 3) with isolated femoral defects treated with OCA was identified and matched by gender, body mass index (BMI), laterality, and OCA size to groups 1 and 2. Patient-specific, defect-specific, intraoperative, and postoperative data including patient-reported outcomes were collected on all patients. The study groups were compared using analyses of variance, paired sample t tests, and χ-square analyses.”

Dr. Hannon told OTW, “Patients with bipolar femoral and tibial osteochondral lesions treated with femoral OCA (regardless of tibial treatment) had greater magnitude of change than the isolated femoral patients treated with OCA, although the magnitude of change differences did not reach statistical significance.”

“The re-operation rate for bipolar defects, as a whole (25%), was lower than for the matched, isolated femoral defect group (40%). Furthermore, the survivorship of the bipolar defects, as a whole (93%), was comparable to the isolated femoral OCA grafts (95%) at an equivalent mean follow-up (3.5 years vs 3.8 years, respectively).”

“Based on our results, clinicians can educate their patients with bipolar defects treated with femoral OCA that regardless of tibial treatment, they will have clinically meaningful improvements functional outcomes and excellent graft survivorship comparable to isolated femoral osteochondral allograft transplantation at over two years.”